bluuebunny/crossref_metadata_2025 huggingface dataset:
A model forL‐methionine production describing oxygen–productivity relationship
Authors: Ranjan Amalendu P. , Nayak Rajib , Gomes James
Published: December 2008

BACKGROUND:The state‐time profile of cell mass, substrate and methionine concentrations of a methionine synthesis process shows strongly nonlinear features. A mathematical representation of this process was developed that conformed to systems analysis required for monitoring and controlling methionine production. The specific growth rate was defined by an exponential term to describe the lag phase in growth, extended before the onset of methionine production and substrate inhibition observed for this process. A switching function was used to describe the relation between methionine synthesis and dissolved oxygen concentration. In addition, the product formation kinetics of this model described the reutilization of methionine feedback regulation whenever the residual substrate concentration dropped below a critical value.

RESULTS:The parameters for the model were determined from experimental data using a nonlinear regression technique. A complete nonlinear systems analysis of the model proved that using this model, the system was controllable and observable. The model prediction of methionine production in controlled and uncontrolled environments was satisfactory. Six statistical measures were employed to validate model prediction and its adequacy was shown through simulations.

CONCLUSIONS:The proposed model for methionine production possesses the correct system architecture for application in process control. It predicts satisfactorily the relationship between methionine synthesis and dissolved oxygen, and time profiles of state variables. Copyright © 2008 Society of Chemical Industry
Technical and economic comparison of conventional and electrochemical coagulation processes
Authors: Cañizares Pablo , Martínez Fabiola , Jiménez Carlos , Sáez Cristina , Rodrigo Manuel A.
Published: December 2008

BACKGROUND: Electrocoagulation is an alternative to the conventional coagulation method, to treat different types of waters and wastewaters. Although there have been many reports on the technical suitability of electrocoagulation, no study has made a direct comparison of the economics of the two processes.

RESULTS: Concerning the technical feasibility, no significant differences were found in the results achieved by the two technologies in the treatment of synthetic suspensions, emulsions and solutions of dyes, when the same values of pH and aluminium concentration were adopted in the reaction systems. Regarding the economic comparison, the electrocoagulation process presents lower operating costs for low and intermediate aluminium doses, but results depend on the particular coagulant reagent selected at high doses. The highest operational costs were obtained with conventional coagulation with aluminium sulphate (in the range 3–60 mg dm−3 aluminium). Comparing electrocoagulation and conventional coagulation with aluminium polychloride, the electrocoagulation process presents lower operational costs for low and intermediate doses. However, this situation changes for high aluminium doses.

CONCLUSION: Coagulation and electrocoagulation techniques give very similar yields in the removal of different types of pollutants; therefore an economic comparison is of major importance in order to recommend the use of one of the technologies. Nevertheless, it has to be noted that operational costs are of the same order of magnitude for the two processes. Thus, the cost of the electrocoagulation process compares favourably with that of conventional coagulation for small coagulant demands, but the results at high doses depend on the particular coagulant reagent selected. Copyright © 2008 Society of Chemical Industry
Design‐based life cycle assessment of hazardous air pollutant control options at pulp and paper mills: a comparison of thermal oxidation to photocatalytic oxidation and biofiltration
Authors: Babbitt Callie W. , Stokke Jennifer M. , Mazyck David W. , Lindner Angela S.
Published: December 2008

BACKGROUND: The forest products industry produces valuable industrial chemicals, wood products, and consumer goods, but is also responsible for the emission of significant quantities of hazardous air pollutants. Although many air pollution control options are available, little is known about the overall environmental impacts of implementing each option. Therefore, a life cycle assessment (LCA) was conducted to compare energy and raw material inputs, air emissions, and environmental impacts associated with construction and operation of two air pollution control systems: regenerative thermal oxidation (RTO) with wet scrubbing and photocatalytic oxidation (PCO) with biofiltration.

RESULTS: LCA results indicated that environmental impacts to resource depletion, photochemical oxidant formation, and acidification were 20% higher for the use of a RTO‐scrubber than for the PCO‐biofilter. In addition, at least 25% of the RTO impacts were due to infrastructure requirements. However, the PCO‐biofilter system was responsible for more environmental impact in categories of global warming and human toxicity, because of the packing materials required and the electricity use for the PCO reactor.

CONCLUSIONS: The PCO‐biofilter system could be a promising, environmentally‐friendly alternative to traditional RTO devices, provided that this system is modified to decrease resource and energy demands. Copyright © 2008 Society of Chemical Industry
Influence of calcitonin administration on ultimobranchial and parathyroid glands of pigeon, Columba livia
Authors: Yadav Seema , Srivastav Ajai Kumar
Published: December 2008

Pigeons were divided into two numerically equal groups (A and B) containing 30 specimens each. Birds from group A were intraperitoneally injected daily with 0.1 mL/100 g body wt of vehicle (0.1 M acetate buffer, pH 4.3 containing 0.1% gelatin). Specimens from group B were intraperitoneally injected daily with 1 μg/100 g body wt of salmon calcitonin. Six birds were sacrificed from each group 2 h after the last injection on 1st, 3rd, 5th, 10th, and 15th day of the experiment. After collection of blood samples, ultimobranchial and parathyroid glands were fixed for histological studies. In calcitonin‐treated C. livia, the plasma calcium levels exhibit a progressive decline from day 1 till day 5. On day 15, the levels become more or less similar to the control value. No change has been noticed on day 1 in the plasma phosphate levels of calcitonin‐treated C. livia. The levels decrease progressively from day 3 to day 5; thereafter, it exhibits an elevation so that on day 15, normal plasma phosphate levels is achieved. The ultimobranchial gland of C. livia exhibits no change up to day 5 following calcitonin treatment. The nuclear volume of ultimobranchial cells exhibits a decrease on day 10. This response progresses up to day 15. Few degenerating cells are also discerned following 15 days calcitonin treatment. The parathyroid gland of calcitonin‐treated C. livia exhibits no histological alteration up to day 3. The nuclear volume of parathyroidal cells exhibits a progressive increase from day 3 till the close of the experiment (day 15). Moreover, the gland exhibits more compactness on day 10 and day 15. Few degenerating cells are encountered after day 15 following calcitonin treatment. Microsc. Res. Tech. 2009. © 2008 Wiley‐Liss, Inc.
Recognition, presence, and survival of locust central nervous glia in situ and in vitro
Authors: Gocht Daniela , Wagner Simone , Heinrich Ralf
Published: December 2008

Insect glial cells serve functions for the formation, maintenance, and performance of the central nervous system in ways similar to their vertebrate counterparts. Characterization of physiological mechanisms that underlie the roles of glia in invertebrates is largely incomplete, partly due to the lack of markers that universally label all types of glia throughout all developmental stages in various species. Studies on primary cell cultures from brains of Locusta migratoria demonstrated that the absence of anti‐HRP immunoreactivity, which has previously been used to identify glial cells in undissociated brains, can also serve as a reliable glial marker in vitro, but only in combination with a viability test. As cytoplasmic membranes of cultured cells are prone to degradation when they lose viability, only cells that are both anti‐HRP immunonegative and viable should be regarded as glial cells, whereas the lack of anti‐HRP immunoreactivity alone is not sufficient. Cell viability can be assessed by the pattern of nuclear staining with DAPI (4′,6‐diamidino‐2‐phenylindole), a convenient, sensitive labeling method that can be used in combination with other immunocytochemical cellular markers. We determined the glia‐to‐neuron ratio in central brains of fourth nymphal stage of Locusta migratoria to be 1:2 both in situ and in dissociated primary cell cultures. Analysis of primary cell cultures revealed a progressive reduction of glial cells and indicated that dead cells detach from the substrate and vanish from the analysis. Such changes in the composition of cell cultures should be considered in future physiological studies on cell cultures from insect nervous systems. Microsc. Res. Tech. 2009. © 2008 Wiley‐Liss, Inc.
Purinergic receptor activation evokes neurotrophic factor neuropeptide Y release from neonatal mouse olfactory epithelial slices
Authors: Kanekar Shami , Jia Cuihong , Hegg Colleen Cosgrove
Published: December 2008

One premise regarding the mechanism of injury‐evoked neuroregeneration is that injured cells induce the release of neurotrophic factors to trigger neurogenesis. Extracellular purine nucleotides exert multiple neurotrophic actions in the central nervous system mediated via activation of purinergic receptors. However, whether purinergics have a neurotrophic role in the olfactory neuroepithelium has not been investigated. Thus, we monitored the ATP‐induced release of neuropeptide Y (NPY), a neuropeptide that increases neuroproliferation in the olfactory epithelium. To visualize NPY release, slices of olfactory epithelium from neonatal mice were cultured on nitrocellulose paper. Immunoassays of the nitrocellulose demonstrated NPY immunoreactivity in regions corresponding to the olfactory epithelium of the nasal cavity. One hour of exposure to exogenous ATP (100, 500 μM) significantly increased the number of olfactory epithelium slices that released NPY from 25% ± 6% to 60% ± 7% or 71% ± 10% (P= 0.001). The purinergic receptor antagonists pyridoxalphosphate‐6‐azophenyl‐2′,4′‐disulfonic acid (PPADS; 25 μM) and suramin (100 μM) significantly reduced the number of olfactory epithelium slices exhibiting ATP‐evoked NPY release to 18% ± 11% (P= 0.004), indicating that NPY release is mediated by activation of purinergic receptors. Released NPY was quantified by enzyme and radioimmunoassays. Exogenous ATP or UTP significantly increased the amount of NPY released. Overall, this study demonstrates that purinergic receptor activation mediates the release of neurotrophic factor NPY in the olfactory epithelium and provides pharmacological targets to promote regeneration of damaged olfactory epithelium. © 2008 Wiley‐Liss, Inc.
The neuronal apoptotic death in global cerebral ischemia in gerbil: Important role for sodium channel modulator
Authors: Brahma Manoja Kumar , Dohare Preeti , Varma Saurabh , Rath Srikanta Kumar , Garg Puja , Biswal Prasanta Kumar , Chowdhury Piyali Dhar , Ray Madhur
Published: December 2008

Global ischemia was induced in gerbil by bilateral occlusion of the common carotid arteries for 5 min. Sodium ionophore monensin or sodium channel blocker tetrodotoxin (TTX) was administered at doses of 10 μg/kg, i.p., 30 min before ischemia induction; the dose was repeated after 22 hr. Subsequently, brain infarct occurred, determined at 24 hr after occlusion. Large, well‐demarcated infarcts were observed in both hemispheres, an important observation because it critically influences the interpretation of the data. Because nitric oxide (NO) production is thought to be related to ischemic neuronal damage, we examined increases in Ca2+ influx, which lead to the activation of nitric oxide synthase (NOS). Then we evaluated the contributions of neuronal NOS, endothelial NOS, and inducible NOS to NO production in brain cryosections. The cytosolic release of apoptogenic molecules like cytochrome c and p53 were confirmed after 24 hr of reflow. TUNEL (terminal deoxynucleotidyl transferase dUTP nick‐end labeling) labeling detected the apoptotic cells, which were confirmed in neuron‐rich cell populations. After 24 hr, all the ischemic changes were amplified by monensin and significantly attenuated by TTX treatment. Additionally, the nesting behavior and histological outcomes were examined after 7 day of reflow. The neuronal damage in the hippocampal area and significant decrease in nesting scores were observed with monensin treatment and reduced by TTX pretreatment after day 7 of reflow. To our knowledge, this report is the first to highlight the involvement of the voltage‐sensitive Na+ channel in possibly regulating in part NO system and apoptosis in a cytochrome c–dependent manner in global ischemia in the gerbil, and thus warrants further investigation. © 2008 Wiley‐Liss, Inc.
Fyn kinase is involved in oligodendroglial cell differentiation induced by apotransferrin
Authors: Perez M.J. , Ortiz E.H. , Roffé M. , Soto E.F. , Pasquini J.M.
Published: December 2008

Mechanisms that regulate oligodendroglial cell (OLGc) differentiation are the focus of intensive research in the field of cellular and molecular neurobiology. We have previously shown that the addition of apotransferrin (aTf) to primary OLGc cultures accelerates their differentiation and induces an increase in the expression of different components of the myelin cytoskeleton (CSK) such as actin, tubulin, and some of the microtubule‐associated proteins, particularly the stable tubulin only peptide (STOP). Fyn protein‐tyrosine kinase (Fyn kinase), a member of the Src family, participates in signalling pathways that regulate OLGs/myelin cytoskeletal reorganization. It is essential for myelin development in the central nervous system (CNS), and its absence results in hypomyelination. In the present study, we used both primary cell and N19 cell line cultures to investigate further the mechanisms of action involved in the accelerated differentiation of OLGcs induced by aTf. In particular, we were interested in studying the participation of Fyn kinase in the different pathways involved in the reorganization of the OLGc/myelin cytoskeleton. In agreement with results already published, we found that in OLGcs, Fyn kinase is associated with Tau and tubulin. Using a dominant‐negative of Tau in which the Fyn‐Tau‐microtubules (MTs) interaction is blocked, we found that aTf was unable to induce OLGc morphological differentiation. It was also observed that aTf decreases the activated RhoA content in coincidence with a redistribution of actin immunoreactivity. These results give support to our hypothesis that Fyn kinase plays a key role in the differentiation process of OLGcs promoted by aTf. © 2008 Wiley‐Liss, Inc.
In vivo infusion of UTP and uridine to the deafened guinea pig inner ear: Effects on response thresholds and neural survival
Authors: Fransson Anette , Järlebark Leif E. , Ulfendahl Mats
Published: December 2008

Nucleotides and nucleosides are known to function as neurotransmitters and neuromodulators but have recently been shown to have a trophic effect on neurons. It has previously been shown, in an animal model for cochlear implants, that local infusion of neurotrophic factors intervenes with the degenerative processes occurring after deafening and protects the auditory spiral ganglion neurons so that electrical responsiveness is maintained. Here we test the hypothesis that nucleosides and nucleotides have a similar effect on the acutely damaged inner ear. Pigmented guinea pigs received a cochlear implant electrode for measuring electrically evoked auditory brainstem responses and a miniosmotic pump for delivering drugs directly to the cochlea. The animals were deafened by a 48‐hr infusion with 10% neomycin, followed by 23 days of treatment with primarily UTP, uridine nucleotides, or as control artificial perilymph. Electrically evoked responses were measured weekly, and at the end of the experiment the cochleae were collected and processed for morphological analysis and spiral ganglion neuron counting. Both UTP‐ and uridine‐treated groups showed significantly better response after 23 days of treatment compared with the control group. The densities of spiral ganglion neuron were significantly higher for both treated groups compared with the control group treated with artificial perilymph. The results demonstrate that UTP and uridine rescue auditory neurons and suggest that drugs acting on purinoceptors could be of clinical importance. © 2008 Wiley‐Liss, Inc.
Vessel microport technique for applications in cerebrovascular research
Authors: Chen Lei , Swartz Karin R. , Toborek Michal
Published: December 2008

Cerebrovascular research suffers from a lack of reliable methods with which to deliver exogenous substances effectively into the central nervous system (CNS) of small experimental animals. Here we describe a novel vessel microport surgical technique for a variety of cerebrovascular applications that is reproducible and well tolerated in mice. The procedure is based on the insertion of a vessel microport into the external carotid artery for substance delivery into the CNS via the internal carotid artery. The method results in selective substance delivery into the ipsilateral hemisphere. Other novel aspects of this surgical technique include the ability to perform multiple injections, study of conscious mice well removed from surgery, and lack of occlusion of the common or internal carotid artery that allows carotid flow to be maintained. The feasibility of this technique has been validated by infusion of HIV Tat protein to induce permeability of the blood–brain barrier and by implantation of tumor cells to establish a brain metastasis model. Thus, the described vessel microport technique can be employed in a variety of cerebrovascular research applications. © 2008 Wiley‐Liss, Inc.
MRG15, a component of HAT and HDAC complexes, is essential for proliferation and differentiation of neural precursor cells
Authors: Chen Meizhen , Takano‐Maruyama Masumi , Pereira‐Smith Olivia M. , Gaufo Gary O. , Tominaga Kaoru
Published: December 2008

Neurogenesis during development depends on the coordinated regulation of self‐renewal and differentiation of neural precursor cells (NPCs). Chromatin regulation is a key step in self‐renewal activity and fate decision of NPCs. However, the molecular mechanism or mechanisms of this regulation is not fully understood. Here, we demonstrate for the first time that MRG15, a chromatin regulator, is important for proliferation and neural fate decision of NPCs. Neuroepithelia from Mrg15‐deficient embryonic brain are much thinner than those from control, and apoptotic cells increase in this region. We isolated NPCs from Mrg15‐deficient and wild‐type embryonic whole brains and produced neurospheres to measure the self‐renewal and differentiation abilities of these cells in vitro. Neurospheres culture from Mrg15‐deficient embryo grew less efficiently than those from wild type. Measurement of proliferation by means of BrdU (bromodeoxyuridine) incorporation revealed that Mrg15‐deficient NPCs have reduced proliferation ability and apoptotic cells do not increase during in vitro culture. The reduced proliferation of Mrg15‐deficient NPCs most likely accounts for the thinner neuroepithelia in Mrg15‐deficient embryonic brain. Moreover, we also demonstrate Mrg15‐deficient NPCs are defective in differentiation into neurons in vitro. Our results demonstrate that MRG15 has more than one function in neurogenesis and defines a novel role for this chromatin regulator that integrates proliferation and cell‐fate determination in neurogenesis during development. © 2008 Wiley‐Liss, Inc.
Effect of estradiol on striatal dopamine activity of female hemiparkinsonian monkeys
Authors: Morissette Marc , Di Paolo Thérèse
Published: December 2008

A higher prevalence and incidence of Parkinson's disease is observed in men, and beneficial motor effects of estrogens are observed in parkinsonian women. In rodents, an effect of estradiol on dopamine systems is documented, whereas much less is known in monkeys. Enkephalin was shown to exert a compensatory modulatory effect on the denervated dopamine nigrostriatal pathway in monkeys and in humans. Moreover in rodents, striatal preproenkephalin mRNA is increased by estrogen treatment. Hence, we investigated the responsiveness of striatal dopamine to estradiol in long‐term ovariectomized monkeys bearing a unilateral lesion with 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) to mimic parkinsonian postmenopausal women. Seven ovariectomized female monkeys received a unilateral MPTP lesion; 4 years after ovariectomy, three received 1‐month treatment with 17β‐estradiol and the others received vehicle. The lesioned striata showed extensive denervation in all monkeys as measured with dopamine and metabolite concentrations assayed by high‐performance liquid chromatography and by autoradiography of the dopamine transporter. The lesioned and intact striata of estradiol‐treated monkeys had increased 3‐methoxytyramine, and lesioned putamen increased dopamine concentrations compared with vehicle‐treated monkeys. Estradiol treatment increased the dopamine transporter in subregions of the intact caudate and putamen compared with the intact striata of vehicle‐treated monkeys, but not in the lesioned striata. Preproenkephalin mRNA levels measured by in situ hybridization were increased in the lesioned striata of vehicle treated monkeys and were not further enhanced in estradiol‐treated monkeys. These results show that long after ovariectomy, modeling postmenopausal hormonal conditions, brain dopamine metabolism, and transporter are still responsive to estradiol. © 2008 Wiley‐Liss, Inc.
Contribution of the striatum to the effects of 5‐HT1A receptor stimulation in L‐DOPA‐treated hemiparkinsonian rats
Authors: Bishop Christopher , Krolewski David M. , Eskow Karen L. , Barnum Christopher J. , Dupre Kristin B. , Deak Terrence , Walker Paul D.
Published: December 2008

Clinical and experimental studies implicate the use of serotonin (5‐HT)1A receptor agonists for the reduction ofL‐3,4‐dihydroxyphenylalanine (L‐DOPA)‐induced dyskinesia (LID). Although raphe nuclei likely play a role in these antidyskinetic effects, an unexplored population of striatal 5‐HT1A receptors (5‐HT1AR) may also contribute. To better characterize this mechanism, L‐DOPA‐primed hemiparkinsonian rats received the 5‐HT1AR agonist ±8‐OH‐DPAT (0, 0.1, 1.0 mg/kg, i.p.) with or without cotreatment with the 5‐HT1AR antagonist WAY100635 (0.5 mg/kg, i.p.) 5 min after L‐DOPA, after which abnormal involuntary movements (AIMs), rotations, and forelimb akinesia were quantified. To establish the effects of 5‐HT1AR stimulation on L‐DOPA‐induced c‐fos and preprodynorphin (PPD) mRNA within the dopamine‐depleted striatum, immunohistochemistry and real‐time reverse transcription polymerase chain reaction, respectively, were used. Finally, to determine the contribution of striatal 5‐HT1AR to these effects, L‐DOPA‐primed hemiparkinsonian rats received bilateral intrastriatal microinfusions of ±8‐OH‐DPAT (0, 5, or 10 μg/side), WAY100635 (5 μg/side), or both (10 μg + 5 μg/side) 5 min after L‐DOPA, after which AIMs and rotations were examined. Systemic ±8‐OH‐DPAT dose‐ and receptor‐dependently attenuated L‐DOPA‐mediated AIMs and improved forelimb akinesia. Striatal c‐fos immunoreactivity and PPD mRNA ipsilateral to the lesion were strongly induced by L‐DOPA, while ±8‐OH‐DPAT suppressed these effects. Finally, intrastriatal infusions of ±8‐OH‐DPAT reduced AIMs while coinfusion of WAY100635 reversed its antidyskinetic effect. Collectively, these results support the hypothesis that the cellular and behavioral properties of 5‐HT1AR agonists are conveyed in part via a population of functional 5‐HT1AR within the striatum. © 2008 Wiley‐Liss, Inc.
Rural tourism development in China
Authors: Gao Shunli , Huang Songshan , Huang Yucheng
Published: December 2008

This paper provides an overview and brief evaluation of China's rural tourism. Beginning with the form of poverty alleviation through tourism, China's rural tourism has undergone over 20 years of development and exhibited some unique features in its development pattern, scale and business operational models in accordance with China's political, social and economic systems. Government plays a decisive role in developing rural tourism in China. However, rural tourism has been valued mainly as an economic means for rural development during the country's modernisation process. Overlooking rurality as an essential issue in rural tourism may lead development to a wrong direction, which could jeopardise the sustainability of the industry. Copyright © 2008 John Wiley & Sons, Ltd.
Expanding the destination image: wine tourism in the Canary Islands
Authors: Scherrer Pascal , Alonso Abel , Sheridan Lynnaire
Published: December 2008

Tourism to the Canary Islands is centred around competitively priced holidays focused on the sun and beach mass tourism experience. A restructure of the islands' wine industry offers opportunities for developing new tourism alternatives based on gourmet products and traditional landscapes. This paper examines the potential of wine tourism from winery operators' perspectives. Challenges to overcome in the development of a successful sustainable local wine tourism industry include the need for expansion of the destination image to reflect the region's wine‐making history and scenic qualities; a shift towards independent high‐yield travellers; and reintroducing local produce in the mass tourism product. Copyright © 2008 John Wiley & Sons, Ltd.
Changes in plant diversity, biomass and soil C, in alpine meadows at different degradation stages in the headwater region of three rivers, China
Authors: Wang C. T. , Long R. J. , Wang Q. L. , Jing Z. C. , Shi J. J.
Published: December 2008

Field surveys and experiment analyses were applied to detect the relationships between plant diversity, community biomass and soil resources at different degradation successional stages in the headwater region of three rivers in an alpine meadow. The chronosequence approach (space‐for‐time substitution) is a viable tool for obtaining integrated information within successional studies. The experimental plots were located in the Guoluo area, which is part of the source region for the Yangtze and Yellow Rivers. The results showed not only that the quantities of roots and soil that are ‘carriers’ for cultivating soil roots were altered not only by disturbance (including overgrazing) and environmental factors but also that the proportion of the rhizome to soil at the 0–10 cm soil layer was enhanced by disturbance in heavy degradation. The plant community composition changed, and the number of plant species and the proportions of fine forage decreased. Moreover, soil fertility levels decreased remarkably, and the soil was degenerated. Plant community biomass levels at different degradation successional stages affected the soil microbial biomass carbon, soil organic carbon and also affected soil fertility conditions. Soil organic carbon and soil total nitrogen declined with grassland degeneration, and the distribution of soil organic carbon was influenced greatly. The alpine speciesKobresia pygmaeawas at different degradation successional stages, and the plant community biomass was significantly related to soil nutrients. In the positive successional series, the composition of plant functional groups became complex gradually, plant species richness was gradually enhanced, and the change in the composition of each plant functional group also reflected the restoration degree plant community structure. Copyright © 2008 John Wiley & Sons, Ltd.
Simple devices for measuring complex ultrashort pulses
Authors: Trebino R. , Bowlan P. , Gabolde P. , Gu X. , Akturk S. , Kimmel M.
Published: December 2008

We describe experimentally simple, accurate, and reliable methods for measuring from very simple to potentially very complex ultrashort laser pulses. With only a few easily aligned components, these methods allow the measurement of a wide range of pulses, including those with time‐bandwidth products greater than 1000 and those with energies of only a few hundred photons. In addition, two new, very simple methods allow the measurement of the complete spatio‐temporal intensity and phase of even complex pulses on a single shot or at a tight focus.
Photonic crystal LEDs – designing light extraction
Authors: Wiesmann C. , Bergenek K. , Linder N. , Schwarz U.T.
Published: December 2008

Photonic crystals (PhCs) have attracted much attention during the last decade as a solution to overcome the low extraction efficiency of as‐grown light‐emitting diodes (LEDs). In this review we describe the underlying physics and summarize recent results obtained with PhC LEDs. Here, the main focus is on diffracting PhC. In order to quantify the benefit from the incorporation of PhCs for diffracting light a comparison by simulations between a PhC LED and a standard state‐of‐the‐art LED is carried out. Finally, the impact of the PhC on the LEDs emission characteristics will be discussed with respect to étendue‐limited applications.
PAMAM Dendrimers as Potential Agents against Fibrillation ofα‐Synuclein, a Parkinson's Disease‐Related Protein
Authors: Rekas Agata , Lo Victor , Gadd Gerry E. , Cappai Roberto , Yun Seok I.
Published: December 2008

The effect of PAMAM dendrimers (generations G3, G4 and G5) on the fibrillation ofα‐synuclein was examined by fluorescence and CD spectroscopy, TEM and SANS. PAMAM dendrimers inhibited fibrillation ofα‐synuclein and this effect increased both with generation number and PAMAM concentration. SANS showed structural changes in the formed aggregates ofα‐synuclein – from cylindrical to dense three‐dimensional ones – as the PAMAM concentration increased, on account of the inhibitory effect. PAMAM also effectively promoted the breaking down of pre‐existing fibrils ofα‐synuclein. In both processes – that is, inhibition and disassociation of fibrils – PAMAM redirectedα‐synuclein to an amorphous aggregation pathway.

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Influence of Layered Silicate on the Self‐Crosslinking of Polychloroprene and Carboxylated Nitrile Rubber
Authors: Das Amit , Stöckelhuber Klaus Werner , Heinrich Gert
Published: December 2008

The effect of organically modified clay on the properties of self‐crosslinkable carboxylated acrylonitrile‐butadiene rubber (XNBR) and polychloroprene rubber (CR) blend is studied. Results of blends produced without crosslinking agents are compared with conventional sulphur cured compounds. Sulphur cured blends exhibit improved physical properties after the incorporation of organophilic‐modified clay. In contrast, the self‐crosslinked blends do not show any reinforcement after the incorporation of the organoclay. XRD spectra show an intercalation of polymer chain into the gallery gap of the clay in both cases. ATR‐IR, DMA and SEM studies of these composites confirm that organoclay particles constrain the self‐crosslinking mechanism. The influence of the organoclay on the crystallisation of CR is also shown.

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Concentration Effect on Temperature Dependence of Gelation Rate in Aqueous Solutions of Methylcellulose
Authors: Chen Kai , Baker Ashley N. , Vyazovkin Sergey
Published: December 2008

The gelation kinetics in methylcellulose solutions of different concentrations is studied by DSC under rising temperature conditions. Isoconversional analysis reveals that the rate is a complex function of temperature represented by a concave downward dependence of the effective activation energy on temperature (E vs. T). Although the initial decreasing portion of the dependence is consistent with the Fisher–Turnbull nucleation model, a description of the final increasing part requires introducing activation energy of diffusion that varies with conversion according to a power law. Parameters of the modified model evaluated from the E versus T dependencies suggest that the diffusion contribution increases with increase in the concentration, whereas the free energy barrier to nucleation remains almost unaffected.

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Macromol. Chem. Phys. 1/2009
Authors: Arun Araichimani , Dullaert Konraad , Gaymans Reinoud J.
Published: December 2008

Cover: In the cover picture nanosized crystalline ribbons of a diblock copolymer with aramide hard segments can be seen, as were observed by AFM phase angle analysis (5 mm × 3.9 mm). The polymer chains run perpendicular to the ribbon length. Further details can be found in the article by A. Arun, K. Dullaert, and R. J. Gaymans on page 48.
Proteomics of brain extracellular fluid (ECF) and cerebrospinal fluid (CSF)
Authors: Maurer Martin H.
Published: December 2008

Mass spectrometry has become the gold standard for the identification of proteins in proteomics. In this review, I will discuss the available literature on proteomic experiments that analyze human cerebrospinal fluid (CSF) and brain extracellular fluid (ECF), mostly obtained by cerebral microdialysis. Both materials are of high diagnostic value in clinical neurology, for example, in cerebrovascular disorders like stroke, neurodegenerative diseases like Alzheimer's Disease, Parkinson's Disease, amyotrophic lateral sclerosis (ALS), traumatic brain injury and cerebral infectious and inflammatory disease, such as multiple sclerosis. Moreover, there are standard procedures for sampling. In a number of studies in recent years, biomarkers have been proposed in CSF and ECF for improved diagnosis or to control therapy, based on proteomics and mass spectrometry. I will also discuss the needs for a transition of research‐based experimental screening with mass spectrometry to fast and reliable diagnostic instrumentation for clinical use. © 2008 Wiley Periodicals, Inc., Mass Spec Rev 29:17–28, 2010
Statistical Distribution Analysis of Polypentenamer cis–trans Structural Units
Authors: Ismail Fadhel , Bendebane Farida , Bouziane Lamia , Boukhari Abbés
Published: December 2008

Summary: The polypentenamer studied in this work, was a product obtained from bulk polymerization of gaseous cyclopentene into condensed polymer in presence of tungsten hexachloride alone as catalyst without any other reagent. This linear polymer doesn't present cross‐links or detectable secondary ramifications. However, its structural unit presents a double bond which can be in different configurations corresponding to cis and trans geometric isomers. The objective of this study was to determine the distribution type of these different structural units constituting the polymer chains. Fractions of cis and trans structural units in polymer chains were calculated from 13CNMR spectra. Statistical distribution of these structural units was observed on high resolution 13CNMR spectra, with the apparition of a quadruplet and a triplet corresponding respectively to the carbon on α and β position. The sextuplet corresponding to the carbon of the double bond was observed clearly in this work (may be because the product polymer is very pure), and confirms the statistical distribution. All peaks corresponding to the different positions of the α‐carbon, the β‐carbon and the olefinic carbon in polymer chains were attributed from statistical analysis of the polypentenamer microstructure.
Formulation of an Environmentally Friendly Adhesive for Wood
Authors: Ibrahim M. N. Mohamad , Ghani A. Md. , Zakaria N. , Shuib S. , Sipaut C. S.
Published: December 2008

Summary: Malaysia has over 4 million hectares of oil palm plantations that yield large amounts of empty fruit bunches (EFB) generated from palm oil milling operations. These forms of lignocellulosic residue pose an environmental hazard if their disposal is not managed in a systematic manner. One of the useful elements extracted from these EFBs is lignin. The general purpose of this study is to explore the potential uses of lignin extracted from soda black liquor (paper and pulping waste) derived from oil palm empty fruit bunches (EFB) in the formulation of a more environmentally friendly wood adhesive. In this work, the potential for replacing phenol with lignin in phenol formaldehyde resin formulation is examined. The quantity of phenol was reduced by synthesizing the resin at a lignin to phenol ratio of 1:1. The physical and chemical properties of lignin phenol formaldehyde resin (LPF) and commercial phenol formaldehyde resin (CPF) were then compared. The infrared spectrum revealed similarities in the functional groups of both LPF and CPF resins. Tensile strength comparisons between both resins revealed that the LPF resin had a higher bonding strength (11.60 MPa more in term of allowable maximum load). In addition, the kinematics viscosity test showed that the LPF resin had lower kinematic viscosity than the CPF resin after 21 days of storage. Finally, the scanning electron microscope images for both resins showed similarities in terms of penetration into wood vessels.
Comparison of Syndiotactic Polystyrene Morphology Obtained Via Heterogeneous and Homogeneous Polymerization with Metallocene Catalyst
Authors: Rahmani Sohrab , Mohammadi Reza , Entezami Ali Akbar
Published: December 2008

Summary: Supported catalyst system for the slurry phase polymerization of styrene in toluene was prepared by the immobilization of 2‐methylindenyltrichlorotitanium(2‐MeIndTiCl3) on silica and activation of this catalyst was performed by methylaluminoxane(MAO) in polymerization media. Homogeneous polymerization of styrene with 2‐methylindenyltrichlorotitanium activated by MAO was performed in toluene. The morphology of obtained syndiotactic polystyrene (sPS) via heterogeneous and homhgeneous catalyst system was compared. Polymerization of styrene by homogeneous catalyst lead to formation of gel and resultant polymers presented a compact and dense texture while the global gelation do not occur with silica supported catalyst at different Ti/SiO2 mol ratios and sPS was obtained as separated particles. Unlike to the homogeneous catalyst, obtained polymers showed a porous texture. Highly porous texture of sPS was obtained with Ti/SiO2 = 0.5% mol ratio.
Synthesis and Characterization of Bagasse Poly(methyl methacrylate) Graft Copolymer
Authors: Sarvi I. , Pourjavadi A. , Aghaei M. A. Noei
Published: December 2008

Summary: Graft copolymerization of methyl methacrylate (MMA) was carried out on bagasse fibers in an aqueous medium using ceric ammonium nitrate (CAN) as initiator under a neutral atmosphere. In order to obtain the optimum condition for graft copolymerization, the effects of initiator concentration, temperature, time of reaction, and monomer concentration were studied. The maximum grafting percent was found to be 122%. The bagasse grafted poly(methyl methacrylate) was characterized by FTIR and its thermal behavior was characterized by TGA.
Preparation of Polyethylene/Layered Silicate Nanocomposites Using In Situ Polymerization Approach
Authors: Ramazani S. A. Ahmad , Tavakolzadeh Fahimeh
Published: December 2008

Summary: In this paper, preparation of polyethylene/clay nanocomposites (PECNC) by in situ Ziegler‐Natta catalyst polymerization was investigated. A Ziegler‐Natta catalyst was first supported on montmorillonite (MMT) type clay and subsequently used for polymerizing ethylene. Clay and clay supported catalyst were characterized by Fourier transmission infrared and ICP method. X‐ray diffraction (XRD) and transmission electron microscopy results show that silicate layers of the mineral clay in prepared nanocomposites were intercalated and exfoliated in the polymeric matrix. Differential scanning calorimetry results show that the prepared nanocomposites have higher crystallization temperature than pure polyethylene.
New Nanoindentation and Nanoscratching Parameters of Thermoplastics
Authors: Naimi‐Jamal M. R. , Kaupp G.
Published: December 2008

Summary: The determination of hardness and modulus values from unloading curves in nanoindentations is particularly troublesome with thermoplastic polymers and the values can strongly depend on the maximal normal force. Quantitative analysis of the loading curves provides reliable nanoindentation coefficients k (µN nm−3/2) as the slopes of linear plots that reliably characterize the pristine polymers and are potent interpolation tools. Kinks in the linear plots (here not observed with isotactic polypropylene (PP‐it)) indicate plastic‐viscoelastic transformations and separate the characterization of the degraded polymer with the smaller nanoindentation coefficients from the pristine polymer. The quantitative analysis of the correct relation between lateral and normal force in nanoscratching reveals the coefficient K (µN−1/2) as a basic extrapolation tool with direct and quantitative access to scratch resistance as a measure for wear that replaces the unfounded and never constant so‐called “friction coefficient FL/FN”. The linear plots of the correct relation between lateral and normal force reveal the occurrence of plastic‐viscoelastic transformations most distinctly by a kink and two linear ranges.
Microwave Assisted Benign Method of Chelating Resin Synthesis Having Different Thermal and Ion Exchange Properties
Authors: Shah B. A. , Shah A. V. , Patel Nayan B.
Published: December 2008

Summary: Microwave irradiation method was used for synthesis of chelating ion exchange resin derived fom Salicylicacid‐Formaldehyde‐Resorcinol (SFR‐M). The resin was characterized by Elemental analysis, FTIR, TGA and SEM. The Broido and Horowitz‐Metzger method were used to calculate the energy of activation (Ea) from TGA. The microwave assisted chelating resin has different thermal behaviour as compared to conventional resin (SFR‐C). The sorption capacities of microwave SFR resin for transition metal ions are higher than conventional SFR resin. The separation of binary mixtures [Cu (II) and Zn (II)] in brass and [Ni (II) and Cd (II)] were successfully carried out using Kd value.
Effect of pH on the Behavior of Hyaluronic Acid in Dilute and Semidilute Aqueous Solutions
Authors: Maleki Atoosa , Kjøniksen Anna‐Lena , Nyström Bo
Published: December 2008

Summary: Viscosity, asymmetric flow field‐flow fractionation (AFFFF) methods, and dynamic light scattering (DLS) experiments were used to characterize the effect of pH on the behavior of dilute and semidilute aqueous buffered solutions of hyaluronic acid (HA). It is shown that degradation of HA occurs at pH < 4 and pH > 11, and in the domain 4 < pH < 11 virtually no disruption of the HA chains occurs. The pH‐induced scission of HA is attributed to the cleavage of glycosidic bonds. In dilute solutions, intramolecular rupture of HA chains occurs and in the semidilute concentration regime network‐fragmentation is observed at low and high pH values. The degree of degradation of HA is most marked at high pH. From the molecular weight and radius of gyration obtained from AFFFF at different pH values, it is clear that the degradation of HA starts at early times after preparation of the solution, and continues for a couple of days. The kinetics of degradation of HA is fastest at high pH.
Processing and Properties of Nanocomposite Filament Yarns with Various Filler Concentrations from Two Different Modification Methods
Authors: Dastjerdi Roya , Mojtahedi M. R. M. , Shoshtari A. M.
Published: December 2008

In this research, the possibility of producing and processing nanocomposite polypropylene filament yarns with permanent antimicrobial efficiency has been assessed by comparing two different methods. Therefore two approaches were used to mix various blending contents of antimicrobial agents based on silver/TiO2nano particles with PP: 1) mixing of PP powder and inorganic nanocomposite powder as an antibacterial agent with the appropriate concentration in a twin screw extruder, preparing modified granules and feeding them to the melt spinning machine, 2) producing masterbatch by a twin screw extruder and blending it with PP in the melt spinning process. In both methods, pure PP and all other combined samples had an acceptable spinnability at the spinning temperature of 240 °C and take‐up speed of 2000 m/min. After producing as‐spun filament yarns by a pilot plant melt spinning machine, samples were drawn, textured and finally weft knitted. Physical and structural properties of as‐spun and drawn yarns with constant and variable draw ratios were investigated and compared. Moreover, the DSC, SEM and FTIR techniques have been used for samples characterization. Finally antibacterial efficiency of knitted samples was evaluated. The experimental results indicated that the maximum crystallinity reduction of modified as‐spun yarns reached 5%. But by applying method 2 (masterbatch), crystallinity of modified as‐spun yarns remained unchanged compared to pure yarn. However, drawing procedure has compensated this difference. By applying the second method, the drawing generally improved the increase of tenacity and modulus of modified fibers, whereas in method 1 the opposite effect was noticed in the case of constant draw ratio. Although the biostatic efficiency of nanocomposite fibers was excellent in both methods, modified fabrics obtained from method 1 showed higher bioactivity.
Study on In‐Situ Compatibilization of the PP/PA6 Blends in Twin Screw Extruders
Authors: Barangi Leila , Taromi Faramarz Afshar , Nazockdast Hossein
Published: December 2008

The in‐situ compatibilization of PP/PA6 blend was studied in a twin screw extruder. The maleic anhydride (MA) content, peroxide concentration, shear rate and feeding order were among the variables investigated. Degree of grafting of samples collected prior to feeding of PA6 into the extruder was measured using titration combined with FTIR technique. From the SEM results it was found that the increasing of initial MA concentration led to larger PA particle size which could be related to secondary reactions between excess MA and PA. The melt linear viscoelastic measurements performed on the blend samples and the obtained relaxation time spectra showed shorter form relaxation time and interfacial relaxation time for one‐step compatibilized sample compared to the sample prepared by the two‐step method with the same degree of grafting. This was attributed to the stronger interfacial interaction of the one‐step compatibilized blend samples which could be resulted from greater efficiency of grafting and/or compatibilization. These results were supported by SEM results which showed smaller particle size for the one‐step compatibilized samples. It was demonstrated that melt linear viscoelastic measurement could provide a great insight into understanding the compatibilization process in twin screw extruder.
Thermodynamic Modeling of Polymer Solution Interface
Authors: Ghiass Majid , Rey Alejandro D.
Published: December 2008

A new method is presented to characterize the interfacial concentration field and interfacial tension between equilibrium polymer solution phases, using readily accessible equilibrium concentration data. The new method is tested and validated using experimental data from different polystyrene solutions and it consists of i) calculation of a universal expression for the concentration gradient coefficient based on the Cahn‐Hilliard model and the Wolf interfacial tension master equation, and ii) development of a highly accurate algebraic function (Kappa distribution) that, for a given equilibrium polymer concentration set, yields the essentially exact interfacial profile predicted by the classical gradient theory for polymer solutions.

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