bluuebunny/crossref_metadata_2025 huggingface dataset:
FEM analysis of stress and deformation in the vicinities of arterial graft anastomosis
Authors: Matsumoto Takeo , Itagaki Hiroyuki , Hayashi Kozaburo
Published: May 2005

Effects of compliance mismatch at end‐to‐end artery/graft anastomoses on the distributions of wall stresses and compliance were studied using the finite element method. The canine common carotid artery (CCA), and expanded polytetrafluoro‐ethylene (EPTFE) thin‐walled graft, and a newly developed polyurethane graft (HS‐2) were used as the models for the host artery, stiff graft, and compliant graft, respectively. Mechanical properties of CCA and HS‐2 were determined from a pressure–diameter test, those of EPTFE graft were obtained by tensile test. Nonlinear elasticity of CCA and HS‐2 was incorporated by iterating a linear FEM analysis: elastic moduli of the vessel walls were changed every 5 mmHg. The results showed that, in the case of the artery/EPTFE anastomosis in which the diameters of the artery and the graft were matched at 0 mmHg, regions of high tensile and shear stresses appeared in the graft near the anastomosis at the intraluminal pressure of 100 mmHg. The stress concentrations were remarkable, even if the diameters were matched at 100 mmHg and the pressure was varied within a physiological range (60–140 mmHg). Moreover, a hypercompliant zone appeared in the arterial wall near the anastomosis in this case. On the other hand, neither high stress concentrations nor hypercompliant zone appeared near the artery/HS‐2 anastomosis. Because the mechanical complications at the compliance‐mismatched anastomosis might finally result in graft failure and occlusion, it is important to match the compliance of graft to that of natural arteries, particularly to improve the patency of small‐calibered arterial grafts. © 1994 John Wiley & Sons, Inc.
Surface modification of polymeric biomaterials by albumin grafting using γ‐irradiation
Authors: Kamath Kalpana R. , Park Kinam
Published: May 2005

Polymeric biomaterial surfaces were modified by albumin grafting to improve their blood compatibility. Albumin molecules were functionalized by introducing double bonds using glycidyl acrylate. The functionalized albumin was covalently attached to various biomaterial surfaces such as polypropylene, polycarbonate, and poly(vinyl chloride) by γ‐irradiation. Surface‐induced platelet adhesion and thrombus formation on the albumin‐grafted surfaces was examined using computer‐enhanced video microscopy and scanning electron microscopy. The amount of the grafted albumin was dependent on the γ‐irradiation dose and the concentration of albumin used for adsorption. The grafted albumin molecules remained on the surface even after exposure to blood for prolonged time periods. This approach was used to graft albumin to polymeric materials of an oxygenator. The albumin grafting resulted in a substantial improvement in blood compatibility as compared to control oxygenators. The covalent grafting of functionalized albumin by γ‐irradiation obviates the need for premodification of chemically inert polymer surfaces. It is useful for albumin grafting to various biomaterial surfaces. © 1994 John Wiley & Sons, Inc.
Biomaterials lubricated for minimum frictional resistance
Authors: Tomita Naohide , Tamai Susumu , Okajima Eigorou , Hirao Yoshihiko , Ikeuchi Ken , Ikada Yoshito
Published: May 2005

To improve the frictional characteristics of a biomaterial, the mechanical performance of a lubricated surface was studied. In vitro friction tests showed that the coefficient of dynamic friction of the lubricated surface was about 0.01 against rabbit bladder and the coefficient of static friction increased with the preload period. The efficacy of a lubricated cystoscope was evaluated by an in vivo test simulating cystoscope operation. The maximal and the total resistance force on the cystoscope model were found to decrease with the surface lubrication. Histological study revealed that urethral damage caused by rubbing with the cystoscope model was reduced by this lubrication technique. Presumably, prolonged retention of water on the lubricated surface region prevented tissue adhesion to the foreign material. © 1994 John Wiley & Sons, Inc.
Physical properties of model viscoelastic materials
Authors: Silver Frederick H. , LiBrizzi Joseph J. , Benedetto Dominick
Published: May 2005

Previous observations on polysaccharides used as viscoelastic agents in ophthalmic surgery suggest that the pseudoplasticity of solutions of hyaluronan (HA) and the low surface tension of hydroxypropylmethylcellulose (HPMC) solutions are physical properties that make these solutions useful clinically. Our laboratories are interested in correlating the physical properties of macromolecular solutions with the ability of these molecules to protect ocular structures during eye surgery. The purpose of this study is to compare the physical properties of model viscoelastics with the properties of HA and HPMC. The results of these studies suggest that polysaccharides that form extended structures in solution at low shear rates and that are characterized by large decreases in the axial ratio at high shear rates, exhibit pseudoplastic behavior. In this study pseudoplasticity is exhibited by polysaccharides with molecular weights in excess of 450 000, and is insensitive to the backbone chemistry for linear macromolecules. In addition, low surface tension is associated with charged macromolecules that have a high positive second virial coefficient. © 1994 John Wiley & Sons, Inc.
Effects of hydroxyapatite and alumina sheaths on postoperative peritendinous adhesions in chickens
Authors: Siddiqi Najam A. , Hamada Yoshiki , Ide Takatoshi , Akamatsu Noriya
Published: May 2005

Two experimental methods for restoring flexor tendon sheath integrity and preventing adhesions around traumatized flexor tendons utilizing artificial tendon sheaths made of either hydroxyapatite (HAp) or alumina were studied in a flexor tendon‐trauma model and compared to a standard tendon sheath repair and a control. Eighty toes were divided equally into a control group, a sheath repair group, an HAp group, and an alumina group. Profundus tendons in zone II were divided and repaired after sublimis excision in all groups. In the sheath repair group, the flexor sheath was also repaired after suturing the tendon. In artificial sheath groups, sheaths made of HAp and alumina were placed over the repair sites to protect them from the surrounding tissues. In the control group, after repairing the tendon, the flexor sheath was excised and no artificial sheaths were used. Each toe was immobilized in a plaster cast for 3 weeks. After three weeks, the plaster cast was removed followed by the removal of the sheaths in the artificial sheath groups through a small incision in the skin in zone II. Active mobilization was encouraged in each group. Postoperative adhesions were examined at 3, 6, 9, and 12 week intervals by using light microscopic techniques. To further explore the effects of artificial sheaths on tendon healing, transmission electron microscopy was done for the HAp and alumina groups at 3, 6, and 12 week intervals. Results demonstrated decreased severity of postoperative adhesions in the HAp as well as in the alumina groups in comparison with the sheath repair and controls. A space resembling the fibro‐osseous canal was formed around the tendon after removing the sheaths. This space remained patent until 12 weeks, 9 weeks after removing the sheaths, and a newly formed tendon sheath‐like structure lined by synovial cells and with a peritenon‐like structure over the tendon surface was observed. In the sheath repair and control groups, the severity of adhesions was decreased with the passage of time, to some extent due to unrestricted mobility. However, a newly formed tendon sheath or peritenon‐like structure was not observed. Electron microscopic studies confirmed good healing at the suture in the HAp and alumina groups with no evidence of necrosis. These results are qualitative in nature as no statistical tests were performed. From these results we conclude that if the tendon is separated from the surrounding granulation tissue by a barrier with good biocompatibility, the tendon can heal with fewer adhesions. Artificial sheaths may be used to reduce adhesions in severe injuries of the hand where postoperative immobilization is necessary due to fractures, vascular, or nerve injuries. © 1995 John Wiley & Sons, Inc.
Influence of fluoride on titanium in an acidic environment measured by polarization resistance technique
Authors: Boere Gert
Published: May 2005

The effect of sodium fluoride on the polarization resistance of titanium was investigated. Titanium plates were exposed to sodium chloride solutions with increasing fluoride concentrations. This was done at pH 7 and 4 at 37°C. The polarization resistance technique was chosen because it is the only electrochemical corrosion test procedure that allows sequential measurements of the same specimen and provides a quantitative basis to estimate corrosion currents unlike measurements of the potential. The results showed a large decrease in polarization resistance with increasing fluoride concentration at pH 4. The polarization resistance at pH 7 remained constant after a slight decrease at a very high value, even with a high fluoride concentration. The results clearly confirm that titanium is attacked by fluoride in an acidic environment. The clinical implications are that fluoride rinses or fluoride gels must have a neutral pH if there is a titanium containing device in the oral environment despite the less prophylactic effectiveness. © 1995 John Wiley & Sons, Inc.
Controlling osteopontin orientation on surfaces to modulate endothelial cell adhesion
Authors: Liu Lingyun , Chen Shengfu , Giachelli Cecilia M. , Ratner Buddy D. , Jiang Shaoyi
Published: May 2005

Osteopontin (OPN) is an important extracellular matrix protein that has been shown to impact wound healing, inflammation, and the foreign body reaction, and has been identified as a potential surface component for engineered biomaterials. OPN contains the arginine‐glycine‐aspartic acid (RGD) moiety that has been shown to mediate cell adhesion through interactions with integrins. In its preferred orientation and conformation on a surface, the functional domains of OPN will be presented to cells to the greatest extent. However, control of protein orientation and conformation is still challenging. In this work, we investigated OPN adsorption and cell adhesion to the OPN layer on self‐assembled monolayers (SAMs) of alkanethiols terminated with various functional groups and on a gold surface. The four SAM terminal groups studied were CH3, OH, NH2, and COOH, representing hydrophobic, hydrophilic but neutral, positively charged, and negatively charged surfaces, respectively. Surface plasmon resonance biosensor and atomic force microscopy were used to characterize the adsorption of OPN on these surfaces. An in vitro cell adhesion assay of bovine aortic endothelial cells was performed to test the functionality of OPN on various SAMs. Surface plasmon resonance results showed that the amount of protein adsorbed on the NH2 surface is close to a monolayer and similar to that on the COOH surface, consistent with the atomic force microscopy results. However, based on cell adhesion experiments, both cell count and average cell spreading area on the NH2 surface are much higher than those on the COOH surface. From these results, it is suggested that the orientation and conformation of OPN on a positively charged NH2 surface is more favorable for cell adhesion and spreading than on a negatively charged COOH surface. The surface coverage of bovine aortic endothelial cells on the surfaces studied decreased in the following order: NH2 > Au > CH3 > COOH > OH whereas the mean cell spreading area decreased in the following order: NH2 > Au > CH3 > COOH. Our studies show that surface properties will alter OPN behavior on surfaces, thus influencing cell interactions. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Evaluation of polymer scaffolds to be used in a composite injectable system for intervertebral disc tissue engineering
Authors: Brown R. Quinn , Mount Andrew , Burg Karen J. L.
Published: May 2005

Adult porcine nucleus pulposus cells were seeded onto gelatin, demineralized bone matrix (DBM), and polylactide scaffolds and cultured in vitro. Cellular behavior in response to the scaffolds was analyzed using biochemical assays, histology, and real‐time quantitative reverse transcriptase‐polymerase chain reaction. Scanning electron microscopy showed pronounced differences in surface texture of the scaffolds. Nucleus pulposus cells attached and assumed an elongated fibroblast‐like morphology on the gelatin and DBM scaffolds. The cells cultured on the gelatin and DBM were metabolically active and expressed types I and II collagen and aggrecan. Detached cellular aggregates with a rounded morphology were noted in the culture tubes containing the polylactide scaffolds. Both surface chemistry and texture likely had a role in causing differences in cellular behavior in response to scaffold material. Promising results were observed using the gelatin and demineralized bone scaffolds, but the behavior of cells cultured on these scaffolds will need to be characterized further. This initial research will be used to direct future work involved in developing this composite injectable tissue engineering system. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Fidelity of micropatterned cell cultures
Authors: Endler Elizabeth E. , Nealey Paul F. , Yin John
Published: May 2005

Methods that enable the culture of micropatterned cells may help advance our fundamental understanding of cell–cell and cell–surface interactions, while facilitating the development and implementation of cell‐based biological assays. However, the long‐term stability of the cell patterns can limit the time scales over which such methods can be informative. Here we used self‐assembling monolayers (SAMs) to localize the adsorption of baby hamster kidney (BHK‐21) cells as well as cells from a murine astrocytoma‐derived cell line (delayed brain tumor) in linear arrays. We tested the effects of surface chemistries, fibronectin pre‐treatments, array dimensions, and cell types on pattern fidelity. Changes in patterns were monitored by phase‐contrast microscopy up to 96 h post‐plating, followed by digital imaging, and these changes were quantified by measuring an “intrusion distance” or the average distance cells extend beyond the initial adhesive/non‐adhesive boundary. Loss of pattern boundaries involved different mechanisms for different cells. Treatment of patterned surfaces with fibronectin prior to plating of cells tended to promote earlier loss of pattern fidelity, and the extent of pattern loss was further augmented for SAMs formed using hydrophobic monolayers. Finally, reduction of gap spacing between adjacent cell arrays promoted pattern loss. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
In vivo identification of the interaction site of ErbB2 extracellular domain with its autoinhibitor
Authors: Hu Pinliang , Feng Jiannan , Zhou Tao , Wang Jianing , Jing Baofeng , Yu Ming , Hu Meiru , Zhang Xuemin , Shen Beifen , Guo Ning
Published: May 2005

Direct interference with the transforming potential of ErbB2 has become a subject of great interest. Disruption of critical ErbB2 ectodomain interactions may lead to novel therapeutic approaches for the treatment of various tumors. The ErbB receptor signaling can be inhibited by rationally designed peptide mimetics based on the subdomains of ErbB ectodomain. The mimetics can bind to the ErbB receptor specifically and block inter‐receptor interactions, resulting in the growth inhibition of ErbB2‐overexpressing cells in vitro. In this study, three‐dimensional structure of herstatin, an autoinhibitor of ErbB2 and ErbB2 ectodomain complex was constructed by computer‐aided molecular modeling. The binding site on ErbB2 ectodomain for herstatin was determined at S1 domain. The mutants of ErbB2 ectodomain were constructed. The interactions of ErbB2 ectodomain and its mutants with herstatin were analyzed for the first time in living cells that coexpressed herstatin and ErbB2 ectodomain or the mutants. The S1 domain in ErbB2 ectodomain was verified as the interaction site with herstatin by immunoprecipitation, confocal microscopy, and fluorescence resonance energy transfer (FRET). The binding region of herstatin on ErbB2 ectodomain might be a potential target region for the drug design. © 2005 Wiley‐Liss, Inc.
Bcl‐2 overexpression in melanoma cells increases tumor progression‐associated properties and in vivo tumor growth
Authors: Trisciuoglio Daniela , Desideri Marianna , Ciuffreda Ludovica , Mottolese Marcella , Ribatti Domenico , Vacca Angelo , Del Rosso Mario , Marcocci Lucia , Zupi Gabriella , Del Bufalo Donatella
Published: May 2005

In this study, we demonstrated that bcl‐2 overexpression in human melanoma cells consistently enhanced the activity of multiple metastasis‐related proteinases, in vitro cell invasion, and in vivo tumor growth. In particular, by using the M14 parental cell line, the MN8 control clone, and two bcl‐2 overexpressing derivatives, we found that bcl‐2 overexpressing cells exposed to hypoxia, when compared to parental cells, expressed higher level of several metalloproteases (MMPs) such as MMP‐2, MMP‐7, MT1‐MMP, and tissue inhibitors of metalloproteases‐1 and ‐2. Moreover, bcl‐2 overexpression in melanoma cells enhanced in vitro invasion on matrigel and, in vivo tumor growth. The more aggressive behavior of bcl‐2 transfectants tumors is significantly associated to an increase in MMP‐2 expression as well as in a more elevated microvessel density as compared to the parental line. Taken together, our data suggest that bcl‐2 plays a pivotal role in the regulation of molecules associated with the migratory and invasive phenotype, contributing, in cooperation to hypoxia, to tumor progression. © 2005 Wiley‐Liss, Inc.
Role of EGF receptor transactivation in phosphoinositide 3‐kinase‐dependent activation of MAP kinase by GPCRs
Authors: Shah Bukhtiar H. , Neithardt Adrienne , Chu David B. , Shah Farzana B. , Catt Kevin J.
Published: May 2005

Many G protein coupled receptors (GPCRs) cause phosphorylation of MAP kinases through transactivation of the epidermal growth factor receptor (EGF‐R), leading to increased cell survival and growth, motility, and migration. Phosphoinositide 3‐kinase (PI3K) is one of the important cell survival signaling molecules activated by EGF‐R stimulation. However, the extent to which EGF‐R transactivation is essential for GPCR agonist‐stimulated PI3K activation is not known. Here we examined the mechanism of PI3K activation that elicits GPCR‐mediated ERK1/2 activation by pathways dependent and/or independent of EGF‐R transactivation in specific cell types. Immortalized hypothalamic neurons (GT1‐7 cells) express endogenous gonadotropin‐releasing hormone receptors (GnRH‐R) and their stimulation causes marked phosphorylation of ERK1/2 and Akt (Ser 473) through transactivation of the EGF‐R and recruitment of PI3K. In C9 hepatocytes, agonist activation of AT1 angiotensin II (AT1‐R), lysophosphatidic acid (LPA), and EGF receptors caused phosphorylation of Akt through activation of the EGF‐R in a PI3K‐dependent manner. However, ERK1/2 activation by these agonists in these cells was independent of PI3K activation. In contrast, agonist stimulation of HEK 293 cells stably expressing AT1‐R caused ERK1/2 phosphorylation that was independent of EGF‐R transactivation but required PI3K activation. LPA signaling in these cells showed partial and complete dependence on EGF‐R and PI3K, respectively. These data indicate that GPCR‐induced ERK1/2 phosphorylation is dependent or independent of PI3K in specific cell types, and that the involvement of PI3K during ERK1/2 activation is not dependent solely on agonist‐induced transactivation of the EGF‐R. Published 2005 Wiley‐Liss, Inc.
Involvement of axonal guidance proteins and their signaling partners in the developing mouse mammary gland
Authors: Morris Joanna S. , Stein Torsten , Pringle Marie‐Anne , Davies Claire R. , Weber‐Hall Stephen , Ferrier Roderick K. , Bell Alexandra K. , Heath Victoria J. , Gusterson Barry A.
Published: May 2005

Mammary morphogenesis in the mouse is driven by specialized structures at the ends of the developing ducts, the terminal end buds (TEB). The mechanisms controlling the precise branching and spacing of the ducts are, as yet, unknown. To identify genes that are associated with migration of TEB and differentiation of the subtending ducts, we developed a novel method of isolating TEB and ducts free of stroma, and compared the gene expression profiles of these two isolates using oligonucleotide microarrays. Ninety one genes were upregulated in TEB compared to ducts. Three of these genes,Sprr1A,Sema3B, andBASP1, are associated with axonal growth and guidance. Two additional members of the Sprr family, Sprr2A and 2B, not previously associated with axonal growth, were also highly expressed in TEB. Expression of these genes was confirmed by RT‐PCR and Western blotting, and the cellular distribution of Sprr1A and BASP1 was demonstrated by immunohistochemistry. Other semaphorins, including Sema3C, 4A, 4F and the cancer invasion associated Sema 4D were also expressed in the mouse mammary gland along with the semaphorin receptors, Plexins A2, A3, B2, and D1, and Neuropilins 1 and 2. These results are discussed in the context of other proteins expressed in the developing gland that are known to be downstream effectors of these signaling molecules. We suggest that these genes may influence ductal growth and morphogenesis in the developing mammary gland. © 2005 Wiley‐Liss, Inc.
Changes in secreted and cell associated proteoglycan synthesis during conversion of myoblasts to osteoblasts in response to bone morphogenetic protein‐2: Role of decorin in cell response to BMP‐2
Authors: Gutierrez Jaime , Osses Nelson , Brandan Enrique
Published: May 2005

Proteoglycans have been identified within the extracellular matrices (ECM) of bone and are known to play a role in ECM assembly, mineralization, and bone formation. Bone morphogenetic protein‐2 (BMP‐2) specifically converts the differentiation pathway of C2C12 myoblasts into that of osteoblast lineage cells. Microarray analyses of the mouse myoblast cell line C2C12 and its differentiation into osteoblastic cells in response to BMP‐2 have suggested the up‐regulation of several proteoglycan species, although there is a lack of biochemical evidence for this response. In this study we have biochemically analyzed and characterized the proteoglycan populations that are induced in C2C12 cells upon osteoblastic differentiation produced by BMP‐2. An important and specific increase in the synthesis of secreted decorin was observed in BMP‐2‐treated cells, as compared to untreated myoblasts and myoblasts induced to differentiate into myotubes. Decorin was seen to contain larger glycosaminoglycan (GAG) chains in induced than in non‐induced cells. BMP‐2 also produced an augment in the synthesis of different heparan sulfate proteoglycans such syndecan‐2, ‐ 3, glypican, and perlecan in detergent‐soluble and non‐soluble cellular fractions. We also examined whether the evident changes induced by BMP‐2 in secreted decorin could have a functional role. BMP‐2 signaling dependent as well as induction of alkaline phosphatase (ALP) activity was diminished in decorin null myoblasts compared to wild type myoblats although cell surface level of BPM‐2 receptors was unchanged. These results are the first biochemical evidence and analysis for the effect of BMP‐2 on the synthesis of proteoglycan during osteogenic conversion of myoblasts and suggest a role for decorin in cell response to BMP‐2. © 2005 Wiley‐Liss, Inc.
Loss of shear stress induces leukocyte‐mediated cytokine release and blood–brain barrier failure in dynamic in vitro blood–brain barrier model
Authors: Krizanac‐Bengez Ljiljana , Mayberg Marc R. , Cunningham Edwin , Hossain Mohammed , Ponnampalam Stephen , Parkinson Fiona E. , Janigro Damir
Published: May 2005

Brain ischemia is associated with an acute release of pro‐inflammatory cytokines, notably TNF‐α and IL‐6 and failure of the blood–brain barrier. Shear stress, hypoxia‐hypoglycemia, and blood leukocytes play a significant role in blood–brain barrier failure during transient or permanent ischemia. However, these mechanisms have not been studied as independent variables for in vitro ischemia. The present study, using a dynamic in vitro blood–brain barrier model, showed that flow cessation/reperfusion under normoxia–normoglycemia or hypoxia–hypoglycemia without blood leukocytes in the luminal perfusate had a modest, transient effect on cytokine release and blood–brain barrier permeability. By contrast, exposure to normoxic–normoglycemic flow cessation/reperfusion with blood leukocytes in the luminal perfusate led to a significant increase in TNF‐α and IL‐6, accompanied by biphasic blood–brain barrier opening. Enhanced permeability was partially prevented with an anti‐TNF‐α antibody. In leukocyte‐free cartridges, the same levels of IL‐6 had no effect, while TNF‐α caused a moderate increase in blood–brain barrier permeability, suggesting that blood leukocytes are the prerequisite for cytokine release and blood–brain barrier failure during reduction or cessation of flow. These cells induce release of TNF‐α early after ischemia/reperfusion; TNF‐α triggers release of IL‐6, since blockade of TNF‐α prevents IL‐6 release, whereas blockade of IL‐6 induces TNF‐α release. Pre‐treatment of blood leukocytes with the cyclooxygenase (COX) inhibitor, ibuprofen, inhibited cytokine release and completely preserved blood–brain barrier permeability during the reperfusion period. In conclusion, loss of flow (flow cessation/reperfusion) independent of hypoxia–hypoglycemia plays a significant role in blood–brain barrier failure by stimulating leukocyte‐mediated inflammatory mechanisms. © 2005 Wiley‐Liss, Inc.
EEDA: A protein associated with an early stage of stratified epithelial differentiation
Authors: Sun Lijie , Ryan David G. , Zhou Mingyuan , Sun Tung‐Tien , Lavker Robert M.
Published: May 2005

Using suppressive subtractive hybridization, we have identified a novel gene, which we named early epithelial differentiation associated (EEDA), which is uniquely associated with an early stage of stratified epithelial differentiation. In epidermis, esophageal epithelium, and tongue epithelium, EEDA mRNA, and antigen was abundant in suprabasal cells, but was barely detectable in more differentiated cells. Consistent with the limbal location of corneal epithelial stem cells, EEDA was expressed in basal corneal epithelial cells that are out of the stem cell compartment, as well as the suprabasal corneal epithelial cells. The strongest EEDA expression occurred in suprabasal precortical cells of mouse, bovine, and human anagen follicles. Developmental studies showed that the appearance of EEDA in embryonic mouse epidermis (E 15.5) coincided with morphological keratinization. Interestingly, EEDA expression is turned off when epithelia were perturbed by wounding and by cultivation under both low and high Ca2+ conditions. Our results indicate that EEDA is involved in the early stages of normal epithelial differentiation, and that EEDA is important for the “normal” differentiation pathway in a wide range of stratified epithelia. © 2005 Wiley‐Liss, Inc.
Undesired components in the transformation of biomass pyrolysis oil into hydrocarbons on an HZSM‐5 zeolite catalyst
Authors: Gayubo Ana G , Aguayo Andrés T , Atutxa Alaitz , Valle Beatriz , Bilbao Javier
Published: May 2005

The results of the catalytic transformation on HZSM‐5 zeolite of mixtures of components of biomass pyrolysis oil in the 673–723 K temperature range are evidence of the need for previously separating certain components (aldehydes, oxyphenols and furfural) that undergo severe thermal degradation by forming carbonaceous deposits at the reactor inlet ducts and on the catalyst itself. The deactivation of the catalyst is a consequence of the deposition of two different types of coke: one of catalytic origin (similar to that generated in the transformation of methanol and bioethanol) and the other of thermal origin, which is produced by the aforementioned degradation. The remaining oxygenate components react to each other with synergistic effect, which means that their reactivity is higher than that of the pure components. The results show that the aqueous fraction of biomass pyrolysis oil may be transformed into hydrocarbons on acid catalysts similarly to the more familiar transformation of methanol and bioethanol. Copyright © 2005 Society of Chemical Industry
Optimization of volatile fatty acid compositions for hydrogen production by Rhodopseudomonas capsulata
Authors: Shi Xian‐Yang , Yu Han‐Qing
Published: May 2005

The effects of volatile fatty acid (VFA) compositions on the cell growth, H2 production rate and H2 yield have been investigated using mathematical models. The results show that a modified logistic model indicates that the maximum cell growth of 0.03 h−1 was obtained at acetate fraction of 0.571, propionate 0.143 and butyrate 0.286 in the total amount of VFA. The response surface methodology appears to be a useful approach to select appropriate substrate compositions for H2 production. Under the conditions in this work, the fractions of 0.551–0.566 for acetate, 0.204–0.211 for propionate, and 0.230–0.238 for butyrate were optimal for H2 production by Rhodopseudomonas capsulata. Copyright © 2005 Society of Chemical Industry
An attempt to compare the performance of bioscrubbers and biotrickling filters for degradation of ethyl acetate in gas streams
Authors: Koutinas Michalis , Peeva Ludmila G , Livingston Andrew G
Published: May 2005

This study presents a comparison of the efficiency of a bioscrubber and a biotrickling filter (BTF) for the removal of ethyl acetate (EA) vapour from a waste gas stream, under the same operating conditions. The maximum EA elimination capacity achieved in the bioscrubber was 550 g m−3 h−1 with removal efficiency higher than 96%. For higher EA loadings the bioscrubber was oxygen limited, which caused incomplete EA biodegradation. When pure oxygen was fed to the bioscrubber at a rate of 0.02 L min−1, the bioscrubber recovered and could treat higher EA loadings without any oxygen limitation. The BTF achieved EA elimination capacity of 600 g m−3 h−1 with removal efficiency higher than 97% and the dissolved oxygen concentration remained substantially higher than in the bioscrubber. However, severe channelling and blockage of the spray nozzle occurred due to the excessive biomass growth. Overall, the bioscrubber system was easier to operate and control than the BTF, while an enhancement of the oxygen mass transfer in the bioscrubber could potentially increase its performance by up to three times. Copyright © 2005 Society of Chemical Industry
Model‐based specific growth rate control for Pichia pastoris to improve recombinant protein production
Authors: Ren Haitao , Yuan Jingqi
Published: May 2005

Constant specific growth rate control in the methanol growth phase was investigated for the fed‐batch cultivation of Pichia pastoris expressing recombinant human serum albumin (rHSA). The methanol feeding strategy was determined based on an earlier proposed macrokinetic model to maintain the specific growth rate at preset levels. The experimental results demonstrate that the control strategy of constant specific growth rate is more effective than that of constant feeding rate to maximize production. Furthermore, the most productive setpoint of the specific growth rate is found between 0.005 and 0.006 h−1, which yields protein concentrations higher than 5 g l−1 at 160 h. In addition, a setpoint of 0.008 h−1 is suggested as the upper limit for specific growth rate control for the given expression system. Copyright © 2005 Society of Chemical Industry
Expansion characteristics of an anaerobic fluidized bed reactor with internal biogas production
Authors: Wu Chun‐Sheng , Huang Ju‐Sheng , Gou Hong‐You
Published: May 2005

More realistic dynamic bed‐expansion experiments using a three‐phase anaerobic fluidized bed reactor (AFBR) with and without internal biogas production were conducted for the establishment of correlation equations for the mean volume ratio of wakes to bubbles (k). A predictive model was also developed for the expansion characteristics of the three‐phase AFBR with internal biogas production. The predicted bed‐expansion heights (HGLS) deviated by only ±10% from the experimental measurements for the three‐phase AFBR. According to the modeling results, if a three‐phase AFBR is loaded into a carrier with low specific gravity (dry density of carrier, ρmd = 1.37 g cm−3; wet density of carrier, ρmw = 1.57 g cm−3) and operated at a high superficial liquid velocity (ul = 4.0 cm s−1), the ratio of HGLS to HLS at a high superficial gas velocity (ug = 1.5 cm s−1) can reach as high as 271%. A higher fluidized‐bed height has a greater effect on the bed‐expansion behavior because of the decrease in liquid pressure (surrounding gas bubbles) along the fluidized‐bed height. From parametric sensitivity analyses, HGLS is most sensitive to the parameter reactor width (X), especially within a small ΔX/X0 range of ±10%; sensitive to ρmw, diameter of the carrier, ρmd and total mass of carrier and least sensitive to ul, biofilm thickness and ug. Copyright © 2005 Society of Chemical Industry
A review of catalytic approaches to waste minimization: case study—liquid‐phase catalytic treatment of chlorophenols
Authors: Keane Mark A
Published: May 2005

Effective waste management must address waste reduction, reuse, recovery/recycle and, as the least progressive option, waste treatment. Catalysis can serve as an integral green processing tool, ensuring lower operating pressures/temperatures with a reduction in energy requirements while providing alternative cleaner synthesis routes and facilitating waste conversion to reusable material. The case study chosen to illustrate the role that catalysis has to play in waste minimization deals with the conversion of toxic chlorophenols in wastewater. The presence of chloro‐organic emissions is of increasing concern with mounting evidence of adverse ecological and public health impacts. A critical overview of the existing treatment technologies is provided with an analysis of the available literature on catalytic dechlorination. The efficacy of Pd/Al2O3 to promote the hydrogen‐mediated dechlorination of mono‐ and dichlorophenols is demonstrated, taking account of both the physical and chemical contributions in this three‐phase (solid catalyst and liquid/gaseous reactants) system. Hydrodechlorination activity and selectivity trends are discussed in terms of chloro‐isomer structure, the influence of temperature is discussed, the role of base (NaOH) addition is examined and the feasibility of catalyst reuse is addressed. Copyright © 2005 Society of Chemical Industry
Acid hydrolysis of commercial chitosans
Authors: Knill CJ , Kennedy JF , Mistry J , Miraftab M , Smart G , Groocock MR , Williams HJ
Published: May 2005

Commercial chitosans were subjected to controlled acid hydrolysis and their degrees of deacetylation (DD), molecular size and rheological flow profiles determined (pre‐ and post‐hydrolysis) by 1H‐NMR spectroscopy, high‐performance size‐exclusion chromatography and rheometry, respectively. Hydrolysis resulted in DD increases between 4 and 11%. Unhydrolysed chitosans had Mw and Mn values in the ranges 700–1200 and 130–210 kDa, respectively. Chitosan with the smallest initial molecular size averages had the smallest averages after hydrolysis; however, a chitosan with an intermediate initial molecular size proved to be most resistant to hydrolysis. Molecular size trends were paralleled by zero shear viscosity (η0) measurements determined by application of the Williamson model to rheological flow profile data. Viscosity is obviously related to molecular size, but does not necessarily reflect relative ease of hydrolysis, since specific hydrolysis conditions affect structurally similar polysaccharides in different ways (in terms of rate of depolymerisation and de‐N‐acetylation, etc), which are not simply due to differences in molecular size profiles pre‐hydrolysis. Copyright © 2005 Society of Chemical Industry
The interaction between Cu, Pb, Zn and Ni in their biosorption onto polyurethane‐immobilised Sphagnum moss
Authors: Zhang Yue , Banks Charles
Published: May 2005

The uptake of Cu(II), Pb(II), Zn(II) and Ni(II) was investigated both individually and from mixed metal ion solutions using Sphagnum moss biomass immobilised in a polyurethane support. The data were evaluated using the Langmuir isotherm equation, and sorption capacities were calculated for different concentration ranges. It was concluded that care must be taken in presentation and interpretation of results when this modelling approach is applied at low concentrations. Repeated metal loading cycles also gave lower values for sorption capacity compared with the maximum potential value, due to equilibrium effects. The uptake capacity for the different metals on a weight basis was in the order lead > copper > zinc > nickel, but on a molar basis this changed to copper > lead > nickel > zinc. Sorption from a multi‐component metal system showed that lead and copper competed equally for binding sites and much more effectively than zinc and nickel. Equations were derived to predict the percentage effect on a given metal ion of other metals in a multi‐metal system based their behaviour in the relevant single and binary systems. Copyright © 2005 Society of Chemical Industry
Storage of biodegradable polymers by an enriched microbial community in a sequencing batch reactor operated at high organic load rate
Authors: Dionisi Davide , Beccari Mario , Di Gregorio Simona , Majone Mauro , Papini Marco Petrangeli , Vallini Giovanni
Published: May 2005

The production of polyhydroxyalkanoates (PHAs) from organic acids by mixed bacterial cultures using a process based on aerobic enrichment of activated sludge, that selects for mixed microbial cultures able to store PHAs at high rates and yields, is described. Enrichment resulted from the selective pressure established by periodic feeding the carbon source in a sequencing batch reactor (SBR); a mixture of acetic, lactic and propionic acids was fed at high frequency (2 hourly), high dilution rate (1 d−1), and at high organic load rate (12.75 g chemical oxygen demand (COD) L−1 d−1). The performance of the SBR was assessed by microbial biomass and PHA production as well as the composition and polymer content of the biomass. A final batch stage was used to increase the polymer concentration of the excess sludge produced in the SBR and in which the behaviour of the biomass was investigated by determining PHA production rates and yields. The microbial biomass selected in the SBR produced PHAs at high rate [278 mg PHAs (as COD) g biomass (as COD)−1 h−1, with a yield of 0.39 mg PHAs (as COD) mg removed substrates (as COD)−1], reaching a polymer content higher than 50% (on a COD basis). The stored polymer was the copolymer poly(3‐hydroxybutyrate/3‐hydroxyvalerate) [P(HB/HV)], with an HV fraction of 18% mol mol−1. The microbial community selected in the SBR was analysed by DGGE (denaturing gradient gel electrophoresis). The operating conditions of the SBR were shown to select for a restricted microbial population which appeared quite different in terms of composition with respect to the initial microbial cenosis in the activated sludge used as inoculum. On the basis of the sequencing of the major bands in the DGGE profiles, four main genera were identified: a Methylobacteriaceae bacterium, Flavobacterium sp, Candidatus Meganema perideroedes, and Thauera sp. The effects of nitrogen depletion (ie absence of growth) and pH variation were also investigated in the batch stage and compared with the SBR operative mode. Absence of growth did not stimulate higher PHA production, so indicating that the periodic feed regime fully exploited the storage potential of the enriched culture. Polymer production rates remained high between pH 6.5 and 9.5, whereas the HV content in the stored polymer strongly increased as the pH value increased. This study shows that polymer composition in the final batch stage can readily be controlled independently from the feed composition in the SBR. Copyright © 2005 Society of Chemical Industry
Use of ionic liquids as ‘green’ solvents for extractions
Authors: Zhao Hua , Xia Shuqian , Ma Peisheng
Published: May 2005

This review summarizes recent applications of ionic liquids (ILs) as ‘green’ solvents in extractions of a variety of substances, including metal ions, organic and bio‐molecules, organosulfur from fuels, and gases. ILs could also be used along with another ‘green’ technology, supercritical fluid extraction (SFE), for a more effective separation of products from ILs. In addition to their environmentally‐benign feature, ILs have other favorable properties over organic solvents used for extraction, such as adjustable hydrophobicity, polarity and selectivity. Copyright © 2005 Society of Chemical Industry
Evaluation of graphitized glass capillary columns
Authors: Goretti G. , Liberti A. , Pili G.
Published: May 2005

The performance of graphitized glass capillary columns obtained by precoating the inner glass walls with graphitized carbon black has been evaluated. It has been shown that according to the amount of stationary phase coated such columns can operate in gas–liquid‐solid chromatography and in gas–liquid chromatography so that tailor‐made columns for specific separations can be prepared. The versatility of these columns is shown in the separation of various mixtures (terpenes, pesticides, isomeric species and others) of analytical importance.
Quantitative yields of underivatized peptides by HPLC
Authors: Hollaway W. L. , Bhown A. S. , Mole J. E. , Bennett J. C.
Published: May 2005

New methods for peptide separation are being developed. Resolution of peptide mixtures on HPLC with good reproducibility indicates the progress that has already been made in development of supports with useful separation capabilities. At present adsorptive characteristics of the stationary phases may place limitations on the applicability of the technique to underivatized peptides. Hopefully, the application of ionpairing techniques and the development of new support materials will expand the range of application for protein and peptide purification.
On‐line hydrogenation of fatty acid methyl esters in capillary gas chromatography
Authors: Kuzmenko T. E. , Samusenko A. L. , Uralets V. P. , Golovnya R. V.
Published: May 2005

An injection splitter in front of a glass capillary column was used for the hydrogenation of fatty acid methyl esters (FAME) mixtures. Hydrogenation followed by gas chromatographic analysis on capillary columns permitted detection and identification in complicated natural mixtures of branched fatty acids, showing minor structural differences, in quantities down to 10−8g.

The technique described, apart from its suitability for FAME analysis, shows promise for structure determination studies of other classes of compounds.
Thin‐layer gel chromatography of 8‐hydroxyquinoline metal complexes
Authors: Shibukawa M. , Oguma K. , Kuroda R.
Published: May 2005

Gel chromatographic behavior of 8‐hydroxyquinoline (oxine, abbreviated HOx) complexes of zinc, copper, aluminum, gallium and indium has been investigated on thin layers of Styragel 60A and Merckogel OR‐PVA 2000 mostly in chloroform and p‐dioxan media. Except for the stable Cu(Ox)2, the other oxinates exhibit either hydration or decomposition in gel‐solvent‐solute systems, which leads to strong retention or tailing on gel layers. An excess of 8‐hydroxyquinoline present in solvents allows the oxinates to be stabilized, so that well‐defined compact spots come out and migrate. For the Zn(Ox)2 the formation of a self‐adduct is strongly suggested on the basis of gel chromatographic behavior. Elution with the solvent containing pyridine also yields evidence of the adduct formation of zinc oxinate‐nitrogen base.
Thin‐layer adsorption chromatography with mixed mobile phases. 1. Characterization of chromatographic systems showing energetic heterogeneity of adsorbent surfaces with regard to admolecules of solvents and solutes
Authors: Różyło J. K. , Jaroniec J. A. , Kołodziejczyk H. , Jaroniec M.
Published: May 2005

Thin‐layer adsorption chromatography with a multicomponent mobile phase is discussed. A new equation for predicting RM‐values in TLC with mixed mobile phases using the RM‐ValUeS obtained for pure solvents is proposed. This equation takes into account effects of energetic heterogeneity of the adsorbent surface with regard to adsorbed molecules of solvents and solutes. Experimental verification of this equation is presented for RM‐data obtained by TLC using a binary mobile phase.
Preconcentration of samples in sandwich tanks for continuous thin‐layer chromatography
Authors: Soczewiński E. , Matysik G.
Published: May 2005

It is demonstrated that horizontai sandwich tank with two cover plates can be used to preconcentrate sample solutions. Narrow sharply‐defined starting zones are obtained just outside the smaller cover plate when the series of spots of the sample solution are applied on the thin layer and predeveloped with a volatile solvent. After evaporation of the solvent, the whole area of the TLC‐plate is covered with two plates and developed with a suitable solvent.
Optimum gas chromatographic conditions in wall‐coated capillary columns. Extended and simplified forms of the Golay‐equation
Authors: Cramers C. A. , Wijnheymer F. A. , Rijks J. A.
Published: May 2005

Band broadening in capillary columns is satisfactorily described by the Golay‐equation extended to situations of appreciable pressure drop by Giddings. In practice, however, several simplifications are often made. The effect of these simplifications on the calculated values of the minimum plate height and optimum carrier gas velocity are treated systematically.
Advances in two‐dimensional GC with glass capillary columns
Authors: Anderson E. L. , Thomason M. M. , Mayfield H. T. , Bertsch W.
Published: May 2005

A versatile two‐dimensional gas chromatograph is described, consisting of 2 separate ovens, one intermediate trap, an auxiliary inlet, and the necessary hardware to effect off‐line switching according to the principle of Deans. The unit has been designed for use with high resolution glass capillary columns. The performance of individual instrumental components was critically evaluated. Results showed that low dead volume glass to metal connections were required in the manifold and detector lines to minimize extra‐column effects. The mass of the intermediate trap must be low to allow rapid heating. Operational parameters are discussed and examples of some applications are shown.
A problem in etching Pyrex glass capillary columns
Authors: Clarke J. F. Gates
Published: May 2005

Recent attempts to reproduce a literature method for etching of Pyrex glass capillary columns with „etching ether”︁ resulted in reduction of the columns to dust through a violent explosion. Although modifications of the method produced etched columns, we found that less than satisfactory results were achieved. Introduction of etching ether by simply coating the column with a thin film of the ether produced an evenly etched column with well defined whiskers. Several observations made during the etching process will also be discussed.