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Sample records for external ophthalmoplegia peo

  1. Mutations of ANT1, Twinkle, and POLG1 in sporadic progressive external ophthalmoplegia (PEO).

    Science.gov (United States)

    Agostino, A; Valletta, L; Chinnery, P F; Ferrari, G; Carrara, F; Taylor, R W; Schaefer, A M; Turnbull, D M; Tiranti, V; Zeviani, M

    2003-04-22

    To verify the impact of mutations in ANT1, Twinkle, and POLG1 genes in sporadic progressive external ophthalmoplegia associated with multiple mitochondrial DNA (mtDNA) deletions, DNA samples from 15 Italian and 12 British patients were screened. Mutations in ANT1 were found in one patient, in Twinkle in two patients, and in POLG1 in seven patients. Irrespective of the inheritance mode, screening of these genes should be performed in all patients with progressive external ophthalmoplegia with multiple mtDNA deletions.

  2. Screening of PEO1 and mitochondrial genes in sporadic cases of ophthalmoplegia

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    Ashok Singh

    2013-01-01

    Full Text Available Aim: To screen the gene PEO1 and mitochondrial genes in sporadic cases of rare progressive external ophthalmoplegia (PEO patients from North India. Materials and Methods: The nuclear and mitochondrial DNA was isolated from the sporadic PEO patients, and bi-directional sequencing was done in gene PEO1 and mitochondrial genes to capture the mutations relevant to the PEO disease. Results: In the present study, none of the mutations were reported in the coding region of PEO1 gene, while four mutations were observed in mtDNA genes, namely NADH dehydrogenase subunit 2 (ND2, tRNA-Trp, non-coding nucleotides (MT-NC3, and NADH dehydrogenase subunit 5 (MT-ND5. Our study revealed two novel mutations, one in tRNA-Trp and the other in ND2 gene, which may have role in sporadic cases of PEO patients. The absence of novel conserved mutation in tRNA-Trp gene was also confirmed in 110 ethnically matched controls. Conclusion: The sporadic case of PEO disease is not associated with mutations in nuclear gene PEO1. The novel mutation in tRNA-Trp gene and ND2 mutations may have role in the disease.

  3. Sleep disturbances in chronic progressive external ophthalmoplegia.

    NARCIS (Netherlands)

    Smits, B.W.; Westeneng, H.J.; Hal, M.A. van; Engelen, B.G.M. van; Overeem, S.

    2012-01-01

    BACKGROUND: Chronic progressive external ophthalmoplegia (CPEO) is a relatively common mitochondrial disorder. In addition to extraocular muscle weakness, various other organs can typically be affected, including laryngeal and limb muscles, cerebrum, cerebellum, and peripheral nerves. Given this mul

  4. [Progressive external ophthalmoplegia and distal myopathy].

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    Damian, C

    1993-01-01

    A patient, 58 years old, presents progressive blepharoptosis, in both eyes and external ophthalmoplegia. The general somatic examination, shows, at the level of the higher limbs, distal myopathy with muscular hypotony and articular deformities fibrosis and tendinous retraction. On examining the eye bottom we found colloid degeneration in the muscle region. Within the same family a ten-year-old nephew presents congenital ptosis. The muscular biopsy from the levator palpebrae shows muscular degenerative lesions with the reduction of nuclei and the proliferation of conjunctive tissue. It is shown that progressive external ophthalmoplegia must be interpreted as an ocular myopathy. The association with the distal myopathy at the level of the higher limbs, in the presented observation, upholds this pathogeny.

  5. Unilateral external ophthalmoplegia in Miller Fisher syndrome: case report

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    Severn Philip

    2007-04-01

    Full Text Available Abstract Background A description of the diagnostic features of Miller Fisher syndrome. Case presentation The clinical presentation, investigation, and subsequent progress of our patient with clinical unilateral external ophthalmoplegia. Conclusion Our case demonstrates the presentation of clinical unilateral external ophthalmoplegia as part of the full triad of Miller Fisher syndrome.

  6. Mutations of mitochondrial DNA polymerase gammaA are a frequent cause of autosomal dominant or recessive progressive external ophthalmoplegia.

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    Lamantea, Eleonora; Tiranti, Valeria; Bordoni, Andreina; Toscano, Antonio; Bono, Francesco; Servidei, Serena; Papadimitriou, Alex; Spelbrink, Hans; Silvestri, Laura; Casari, Giorgio; Comi, Giacomo P; Zeviani, Massimo

    2002-08-01

    One form of familial progressive external ophthalmoplegia with multiple mitochondrial DNA deletions recently has been associated with mutations in POLG1, the gene encoding pol gammaA, the catalytic subunit of mitochondrial DNA polymerase. We screened the POLG1 gene in several PEO families and identified five different heterozygous missense mutations of POLG1 in 10 autosomal dominant families. Recessive mutations were found in three families. Our data show that mutations of POLG1 are the most frequent cause of familial progressive external ophthalmoplegia associated with accumulation of multiple mitochondrial DNA deletions, accounting for approximately 45% of our family cohort.

  7. Extraocular muscle atrophy and central nervous system involvement in chronic progressive external ophthalmoplegia.

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    Cynthia Yu-Wai-Man

    Full Text Available Chronic progressive external ophthalmoplegia (CPEO is a classical mitochondrial ocular disorder characterised by bilateral progressive ptosis and ophthalmoplegia. These ocular features can develop either in isolation or in association with other prominent neurological deficits (CPEO+. Molecularly, CPEO can be classified into two distinct genetic subgroups depending on whether patients harbour single, large-scale mitochondrial DNA (mtDNA deletions or multiple mtDNA deletions secondary to a nuclear mutation disrupting mtDNA replication or repair. The aim of this magnetic resonance imaging (MRI study was to investigate whether the ophthalmoplegia in CPEO is primarily myopathic in origin or whether there is evidence of contributory supranuclear pathway dysfunction.Ten age-matched normal controls and twenty patients with CPEO were recruited nine patients with single, large-scale mtDNA deletions and eleven patients with multiple mtDNA deletions secondary to mutations in POLG, PEO1, OPA1, and RRM2B. All subjects underwent a standardised brain and orbital MRI protocol, together with proton magnetic resonance spectroscopy in two voxels located within the parietal white matter and the brainstem.There was evidence of significant extraocular muscle atrophy in patients with single or multiple mtDNA deletions compared with controls. There was no significant difference in metabolite concentrations between the patient and control groups in both the parietal white matter and brainstem voxels. Volumetric brain measurements revealed marked cortical and cerebellar atrophy among patients with CPEO+ phenotypes.The results of this study support a primary myopathic aetiology for the progressive limitation of eye movements that develops in CPEO.

  8. Nature and frequency of respiratory involvement in chronic progressive external ophthalmoplegia

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    Smits, B.W.; Heijdra, Y.F.; Cuppen, F.; Engelen, B.G. van

    2011-01-01

    Chronic progressive external ophthalmoplegia (CPEO) is a relatively common mitochondrial disorder. Weakness of the extra-ocular, limb girdle and laryngeal muscles are established clinical features. Respiratory muscle involvement however has never been studied systematically, even though respiratory

  9. Progressive External Ophthalmoplegia and Vision and Hearing Loss in a Patient With Mutations in POLG2 and OPA1

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    Ferraris, Silvio; Clark, Susanna; Garelli, Emanuela; Davidzon, Guido; Moore, Steven A.; Kardon, Randy H.; Bienstock, Rachelle J.; Longley, Matthew J.; Mancuso, Michelangelo; Ríos, Purificación Gutiérrez; Hirano, Michio; Copeland, William C.; DiMauro, Salvatore

    2008-01-01

    Objective To describe the clinical features, muscle pathological characteristics, and molecular studies of a patient with a mutation in the gene encoding the accessory subunit (p55) of polymerase γ (POLG2) and a mutation in the OPA1 gene. Design Clinical examination and morphological, biochemical, and molecular analyses. Setting Tertiary care university hospitals and molecular genetics and scientific computing laboratory. Patient A 42-year-old man experienced hearing loss, progressive external ophthalmoplegia (PEO), loss of central vision, macrocytic anemia, and hypogonadism. His family history was negative for neurological disease, and his serum lactate level was normal. Results A muscle biopsy specimen showed scattered intensely succinate dehydrogenase–positive and cytochrome-c oxidase–negative fibers. Southern blot of muscle mitochondrial DNA showed multiple deletions. The results of screening for mutations in the nuclear genes associated with PEO and multiple mitochondrial DNA deletions, including those in POLG (polymerase γ gene), ANT1 (gene encoding adenine nucleotide translocator 1), and PEO1, were negative, but sequencing of POLG2 revealed a G1247C mutation in exon 7, resulting in the substitution of a highly conserved glycine with an alanine at codon 416 (G416A). Because biochemical analysis of the mutant protein showed no alteration in chromatographic properties and normal ability to protect the catalytic subunit from N-ethylmaleimide, we also sequenced the OPA1 gene and identified a novel heterozygous mutation (Y582C). Conclusion Although we initially focused on the mutation in POLG2, the mutation in OPA1 is more likely to explain the late-onset PEO and multisystem disorder in this patient. PMID:18195150

  10. Mutations in the SPG7 gene cause chronic progressive external ophthalmoplegia through disordered mitochondrial DNA maintenance.

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    Pfeffer, Gerald; Gorman, Gráinne S; Griffin, Helen; Kurzawa-Akanbi, Marzena; Blakely, Emma L; Wilson, Ian; Sitarz, Kamil; Moore, David; Murphy, Julie L; Alston, Charlotte L; Pyle, Angela; Coxhead, Jon; Payne, Brendan; Gorrie, George H; Longman, Cheryl; Hadjivassiliou, Marios; McConville, John; Dick, David; Imam, Ibrahim; Hilton, David; Norwood, Fiona; Baker, Mark R; Jaiser, Stephan R; Yu-Wai-Man, Patrick; Farrell, Michael; McCarthy, Allan; Lynch, Timothy; McFarland, Robert; Schaefer, Andrew M; Turnbull, Douglass M; Horvath, Rita; Taylor, Robert W; Chinnery, Patrick F

    2014-05-01

    Despite being a canonical presenting feature of mitochondrial disease, the genetic basis of progressive external ophthalmoplegia remains unknown in a large proportion of patients. Here we show that mutations in SPG7 are a novel cause of progressive external ophthalmoplegia associated with multiple mitochondrial DNA deletions. After excluding known causes, whole exome sequencing, targeted Sanger sequencing and multiplex ligation-dependent probe amplification analysis were used to study 68 adult patients with progressive external ophthalmoplegia either with or without multiple mitochondrial DNA deletions in skeletal muscle. Nine patients (eight probands) were found to carry compound heterozygous SPG7 mutations, including three novel mutations: two missense mutations c.2221G>A; p.(Glu741Lys), c.2224G>A; p.(Asp742Asn), a truncating mutation c.861dupT; p.Asn288*, and seven previously reported mutations. We identified a further six patients with single heterozygous mutations in SPG7, including two further novel mutations: c.184-3C>T (predicted to remove a splice site before exon 2) and c.1067C>T; p.(Thr356Met). The clinical phenotype typically developed in mid-adult life with either progressive external ophthalmoplegia/ptosis and spastic ataxia, or a progressive ataxic disorder. Dysphagia and proximal myopathy were common, but urinary symptoms were rare, despite the spasticity. Functional studies included transcript analysis, proteomics, mitochondrial network analysis, single fibre mitochondrial DNA analysis and deep re-sequencing of mitochondrial DNA. SPG7 mutations caused increased mitochondrial biogenesis in patient muscle, and mitochondrial fusion in patient fibroblasts associated with the clonal expansion of mitochondrial DNA mutations. In conclusion, the SPG7 gene should be screened in patients in whom a disorder of mitochondrial DNA maintenance is suspected when spastic ataxia is prominent. The complex neurological phenotype is likely a result of the clonal

  11. Effectiveness of Pyridoxine and Pyridostigmine in the Treatment of Vincristine-Induced Bilateral Ptosis and External Ophthalmoplegia: A Case Report

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    Osman Okan Olcaysu

    2014-08-01

    Full Text Available In this manuscript, we present the case of a patient with acute lymphoblastic leukemia who developed vincristine-induced bilateral ptosis and external ophthalmoplegia and who was treated successfully with pyridoxine and pyridostigmine. Pyridostigmine and pyridoxine are promising treatment option in cases of vincristine-induced neuropathy. (Turk J Ophthalmol 2014; 44: 330-1

  12. Effectiveness of Pyridoxine and Pyridostigmine in the Treatment of Vincristine-Induced Bilateral Ptosis and External Ophthalmoplegia: A Case Report

    OpenAIRE

    2014-01-01

    In this manuscript, we present the case of a patient with acute lymphoblastic leukemia who developed vincristine-induced bilateral ptosis and external ophthalmoplegia and who was treated successfully with pyridoxine and pyridostigmine. Pyridostigmine and pyridoxine are promising treatment option in cases of vincristine-induced neuropathy. (Turk J Ophthalmol 2014; 44: 330-1)

  13. Chronic progressive external ophthalmoplegia: II. A qualitative and quantitative electronmicroscopy study of skeletal muscles

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    Elza Dias-Tosta

    1988-06-01

    Full Text Available This study quantifies the maior electron microscopic changes in limb muscle biopsies from 31 out of 34 patients with the syndrome of chronic progressive external ophthalmoplegia. Patients were divided into three clinical groups - A 10 sporadic cases with muscle weakness only; B 9 familial cases with muscle weakness only; C 15 cases with muscle weakness and one or more of the following features: pigmentary retinopathy, cerebellar ataxia, pyramidal signs and peripheral neuropathy. Electron microscopic mitochondrial abnormalities were found in all groups (8 patients from group A, 3 from group B, 14 from group C. Quantitative measurements of certain muscle fibre constituents, using a point-counting technique, revealed decreased myofibril volume-fractions and increased volume-fractions of mitochondria, glycogen and lipid in some biopsies from each group. Mitochondrial volume-fractions correlated positively with lipid content, the proportion of type 1 fibres, and the percentage of fibres with increased oxidative enzyme activity. The three groups defined clinically showed no significant differences in terms of the relative proportions of these measured constituents.

  14. Internuclear Ophthalmoplegia

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    ... Commentary Recent News Scientists Working on Solar-Powered Prosthetic Limbs Exercise a Great Prescription to Help Older Hearts Bavencio Approved for Rare Skin Cancer Older Mothers May Raise Better-Behaved Kids, Study Suggests ... damage to certain connections between nerve centers in the brain stem (the lower part of the brain). In internuclear ophthalmoplegia, the ...

  15. A novel missense adenine nucleotide translocator-1 gene mutation in a Greek adPEO family.

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    Napoli, L; Bordoni, A; Zeviani, M; Hadjigeorgiou, G M; Sciacco, M; Tiranti, V; Terentiou, A; Moggio, M; Papadimitriou, A; Scarlato, G; Comi, G P

    2001-12-26

    Autosomal dominant progressive external ophthalmoplegia (adPEO) is caused by mutations in at least three different genes: ANT1 (chromosome 4q34-35), TWINKLE, and POLG. The ANT1 gene encodes the adenine nucleotide translocator-1 (ANT1). We identified a heterozygous T293C mutation of the ANT1 gene in a Greek family with adPEO. The resulting leucine to proline substitution likely modifies the secondary structure of the ANT1 protein. ANT1 gene mutations may account for adPEO in families with different ethnic backgrounds.

  16. [Chronic progressive external ophthalmoplegia with mitochondrial anomalies. Clinical, histological, biochemical and genetic analysis (9 cases)].

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    Drouet, A

    1996-01-01

    We report the clinical signs and histological findings in nine patients with mitochondrial ocular myopathies. There were four males and five females. Of age ranging from 47 to 82 years. A more often asymetrical ptosis was in all cases of chronic progressive external ophtalmoplegia (CPEO), but muscle weakness in limbs was not usual. The prognosis in this group was good, but ubidecarenone (150 mg/d) used for two cases, did not improve ophtalmoplegia. The serum creatine kinase was normal in eight of nine cases and electromyography showed myopathic changes in three cases. Histoenzymatic analysis of the muscle biopsy and biochemical studies of mitochondria isolated from the muscle sample demonstrated mitochondrial myopathy associated with partial deficiency of complexes I and/or IV of the electron transfer chain. One of seven patients studied had single deletion by Southern blot analysis, in a heteroplasmic state and another an A-->G transition at position 3243 within the mitochondrial tRNA leu (UUR) gene. Chronic progressive external ophtalmoplegia, without large deletion, may have abnormality in other coding regions of mt DNA such as tRNA, rRNA or protein genes.

  17. Selected case from the Arkadi M. Rywlin International Pathology Slide Series: Mitochondrial myopathy presenting with chronic progressive external ophthalmoplegia (CPEO): a case report.

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    Bisceglia, Michele; Crociani, Paola; Fogli, Danilo; Centola, Antonio; Galliani, Carlos A; Pasquinelli, Gianandrea

    2014-11-01

    A 43-year-old female patient diagnosed with chronic progressive external ophthalmoplegia (CPEO) because of mitochondrial myopathy documented by muscle biopsy is presented. The chief complaints were represented by blepharoptosis and ophthalmoplegia. The muscle biopsy was evaluated by histology, using the appropriate histochemical and histoenzimological stains. Ragged red fibers with Gomori trichrome stain were seen, which showed cytochrome c oxydase deficiency and abnormal succinate dehydrogenase staining in around 20% of muscle fibres. Electron microscopy was also performed which demonstrated abnormal, hyperplastic, pleomorphic, and hypertrophic mitochondria, characterized by paracrystalline inclusions arranged in parallel rows ("parking-lot" inclusions), consisting of rectangular arrays of mitochondrial membranes in a linear or grid-like pattern. In conclusion, mitochondrial myopathy was definitely diagnosed. Although molecular analysis, which was subsequently carried out, failed to reveal mutations in the mitochondrial DNA or in selected nuclear genes, the pathologic diagnosis was not changed. The differential diagnosis of CPEO with other forms of ocular myopathies as well as the possible association of CPEO with systemic syndromes is discussed. Ophtalmologists and medical internists should always suspect CPEO when dealing with patients affected by ocular myopathy, either in its pure form or in association with other myopathic or systemic signs.

  18. 眼外肌麻痹患者257例的临床特征及病因分析%Analysis the clinical characteristic and etiology of external ophthalmoplegia 257 cases

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    雷涛; 李正仪; 刘轩; 王润生; 洪舟

    2013-01-01

    Objective To discussion the clinical characteristics and etiology of external ophthalmoplegia. Methods Collected and retrospectively analyzed the etiology and clinical characteristic of 257 external ophthalmoplegia patients. Records of the patient history, clinical manifestations and corresponding neurological department of internal medicine, Ophthalmology, Endocrinology and Radiographic examination. Results Simple ptosis in 80 cases, 131 cases of simple binocular diplopia, ptosis and diplopia in 39 cases, 7 cases of eyeball fixation. 223 cases of unilateral paralysis of extraocular muscle, 32 cases of bilateral extraocular muscle paralysis. The levator paralysis in 119 cases, unilateral put on 98 cases of eyelid muscle paralysis, bilateral put on 21 cases of eyelid muscle paralysis. 84 cases of lateral rectus muscle palsy, 56 cases of unilateral lateral rectus muscle palsy, 6 cases of bilateral lateral rectus paralysis.178 cases of extraocular ophthalmoplegia of oculomotor control, 40 cases with complete paralysis, 117 cases with incomplete paralysis, combined with other extraocular ophthalmoplegia in 21 cases. Superior oblique palsy in 24 cases, alone of superior oblique palsy in 17 cases, combined with other extraocular ophthalmoplegia in 7 cases. 82 cases with orbital local pain, 12 cases with mydriasis. In 163 cases of ocular motor neuropathy patients, single oculomotor nerve palsy in 148 cases, accounting for 90.8%, 15 cases of multiple oculomotor nerve paralysis, 9.2%. Eye movement nerve injury in 110 cases, accounting for 67.5%, 16 cases, nuclear damage was 9.8%, between nuclear damage in 13 cases, accounting for 8%, nuclear damage 24 cases accounted for 14.7%.There are 14 kinds of external ophthalmoplegia etiology in this group. including myasthenia gravis, diabetic oculomotor nerve injury, atherosclerosis and ischemic ocular motor nerve injury, local nonspecific inflammatory, traumatic, local space-occupying lesions, thyroid disease, Increased

  19. Sporadic PEO caused by a novel POLG variation and a Twinkle mutation: digenic inheritance?

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    Da Pozzo, Paola; Rubegni, Anna; Rufa, Alessandra; Cardaioli, Elena; Taglia, Ilaria; Gallus, Gian Nicola; Malandrini, Alessandro; Federico, Antonio

    2015-09-01

    Progressive external ophthalmoplegia (PEO) with multiple deletions of mitochondrial DNA (mtDNA) is associated with several mutations in nuclear genes. They include POLG, POLG2, ANT1, C10orf2/Twinkle, and OPA1. However, digenic inheritance in mitochondrial disorders has been documented in a few cases over the years. Here we describe an 80-year-old man with sporadic PEO associated with mtDNA deletions. Sequencing of the POLG revealed a novel heterozygous mutation (c.2831A>G; p.Glu944Gly), predicted in silico as damaging, in the patient who also carried a heterozygous mutation in C10orf2/Twinkle (c.1142T>C; p.Leu381Pro). This case provides a second report of a PEO with different mutations in the POLG and C10orf2/Twinkle genes, supporting the hypothesis that the PEO phenotype can be determined by the co-existence of two abnormalities in separate genes, both involved in the maintenance and stability of mtDNA. Finally, this study expands the spectrum of POLG mutations and highlights the need to sequence the whole set of nuclear genes associated with PEO and multiple mtDNA deletions.

  20. Mitochondrial DNA mutations in patients with chronic progressive external ophthalmoplegia and Kearns-Sayre syndrome%慢性进行性眼外肌瘫痪和Kearns-Sayre综合征的线粒体DNA突变分析

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    王朝霞; 袁云; 高枫; 戚豫; 沈定国; 陈清棠

    2003-01-01

    目的探讨慢性进行性眼外肌瘫痪(chronic progressive external ophthalmoplegia, CPEO)和Kearns-Sayre综合征(Kearns-Sayre syndrome, KSS)的线粒体DNA(mitochondrial DNA, mtDNA)突变特点.方法用Southern印迹方法检测7例CPEO和4例KSS患者的肌肉组织mtDNA,并进一步用聚合酶链反应产物直接测序来明确缺失的具体范围;用聚合酶链反应-限制性内切酶分析法检测有无mtDNA A3243G点突变.结果发现5例患者(2例CPEO和3例KSS)存在mtDNA的大片段缺失;1例KSS患者存在A3243G点突变.5例大片段缺失的大小及缺失范围各不相同,从3.0~8.0 kb不等,缺失型mtDNA占总mtDNA的比例为37.6%~87.0%.聚合酶链反应产物测序表明这5例缺失类型均未见文献报道.结论与CPEO和KSS患者相关的最常见的mtDNA突变为大片段缺失,A3243G点突变也可在少数患者中检测到.

  1. Congenital neuromuscular disease with type I fibre hypotrophy, ophthalmoplegia and myofibril degeneration.

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    Sugie, H.; Hanson, R.; Rasmussen, G.; Verity, M A

    1982-01-01

    We report a 7-year-old boy with progressive, early onset somatic and cranial muscle weakness associated with external ophthalmoplegia, facial weakness, type I fibre hypotrophy and myofibril degeneration. We separate this condition from congenital fibre type disproportion because of the facial weakness, ophthalmoplegia, central nucleation, and lysis in type I fibres. The case, which is similar to that described by Bender and Bender (1977), nosologically should be classified between the centron...

  2. Esthesioneuroblastoma presenting with complete external ophthalmoplegia.

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    García-Santana, Sheila M; Rodríguez, Julio A; Serrano, Luis; Hedges, Thomas R

    2009-01-01

    An 85-year-old male presented with unilateral third, fourth, and sixth cranial nerve palsies. Neuroimaging revealed a mass involving the medial wall of the left cavernous sinus, without orbital involvement. Biopsy of the mass provided a pathologic diagnosis of esthesioneuroblastoma.

  3. Genetics Home Reference: progressive external ophthalmoplegia

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    ... most DNA is packaged in chromosomes within the nucleus (nuclear DNA), mitochondria also have a small amount ... large segments of mtDNA in muscle cells. The size of the deleted region can range from 2, ...

  4. Congenital neuromuscular disease with type I fibre hypotrophy, ophthalmoplegia and myofibril degeneration.

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    Sugie, H; Hanson, R; Rasmussen, G; Verity, M A

    1982-06-01

    We report a 7-year-old boy with progressive, early onset somatic and cranial muscle weakness associated with external ophthalmoplegia, facial weakness, type I fibre hypotrophy and myofibril degeneration. We separate this condition from congenital fibre type disproportion because of the facial weakness, ophthalmoplegia, central nucleation, and lysis in type I fibres. The case, which is similar to that described by Bender and Bender (1977), nosologically should be classified between the centronuclear myopathies and congenital fibre type disproportion, and most likely represents a congenital or neonatal disturbance of trophic interaction between nerve and muscle.

  5. Complications of vision loss and ophthalmoplegia during endoscopic sinus surgery

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    Maharshak I

    2013-03-01

    Full Text Available Idit Maharshak,1,2 Jenny K Hoang,3 M Tariq Bhatti2,4 1Department of Ophthalmology, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel; 2Department of Ophthalmology, 3Department of Radiology (Division of Neuroradiology, 4Department of Medicine (Division of Neurology, Duke Eye Center and Duke University Medical Center, Durham, NC, USA Objective: To describe two rare cases of concurrent vision loss and external ophthalmoplegia following powered endoscopic sinus surgery (ESS. Design: Observational case report. Results: The records of two patients who underwent powered ESS and developed multiple concurrent ophthalmic complications were retrospectively reviewed for clinical history, neuro-ophthalmologic examination, and imaging findings. Patient 1 developed a retinal vascular occlusion and complete loss of adduction. Patient 2 developed an orbital hemorrhage, optic neuropathy, and a restrictive global ophthalmoplegia. Similar published case reports were also reviewed. Conclusion: Despite advances in powered ESS technique and instrumentation, serious ophthalmic complications can still occur. Inadvertent entry into the medial orbital wall can result in a combination of blindness and ocular motility dysfunction. The variety of mechanisms responsible for these complications underscores the importance of thorough pre- and postoperative clinical examination and review of imaging studies. Keywords: sinus surgery, orbit, extra ocular muscle injury, blindness

  6. Mutations in AAC2, equivalent to human adPEO-associated ANT1 mutations, lead to defective oxidative phosphorylation in Saccharomyces cerevisiae and affect mitochondrial DNA stability.

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    Fontanesi, Flavia; Palmieri, Luigi; Scarcia, Pasquale; Lodi, Tiziana; Donnini, Claudia; Limongelli, Anna; Tiranti, Valeria; Zeviani, Massimo; Ferrero, Iliana; Viola, Anna Maria

    2004-05-01

    Autosomal dominant and recessive forms of progressive external ophthalmoplegia (adPEO and arPEO) are mitochondrial disorders characterized by the presence of multiple deletions of mitochondrial DNA in affected tissues. Four adPEO-associated missense mutations have been identified in the ANT1 gene. In order to investigate their functional consequences on cellular physiology, we introduced three of them at equivalent positions in AAC2, the yeast orthologue of human ANT1. We demonstrate here that expression of the equivalent mutations in aac2-defective haploid strains of Saccharomyces cerevisiae results in (a) a marked growth defect on non-fermentable carbon sources, and (b) a concurrent reduction of the amount of mitochondrial cytochromes, cytochrome c oxidase activity and cellular respiration. The efficiency of ATP and ADP transport was variably affected by the different AAC2 mutations. However, irrespective of the absolute level of activity, the AAC2 pathogenic mutants showed a significant defect in ADP versus ATP transport compared with wild-type AAC2. In order to study whether a dominant phenotype, as in humans, could be observed, the aac2 mutant alleles were also inserted in combination with the endogenous wild-type AAC2 gene. The heteroallelic strains behaved as recessive for oxidative growth and petite-negative phenotype. In contrast, reduction in cytochrome content and increased mtDNA instability appeared to behave as dominant traits in heteroallelic strains. Our results indicate that S. cerevisiae is a suitable in vivo model to study the pathogenicity of the human ANT1 mutations and the pathophysiology leading to impairment of oxidative phosphorylation and damage of mtDNA integrity, as found in adPEO.

  7. An unusual case of total ophthalmoplegia

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    Chowdhury Ravindra

    2009-01-01

    Full Text Available An eight-year-old male child presented with drooping of the left eyelid with a history of penetrating injury of hard palate by an iron spoon seven days ago, which had already been removed by the neurosurgeon as the computed tomography scan revealed a spoon in the left posterior ethmoid and sphenoid bone penetrating into the middle cranial fossa. On examination, visual acuity was 20/20 in each eye and left eye showed total ophthalmoplegia. Oral cavity revealed a hole in the left lateral part of the hard palate. We managed the case with tapering dose of systemic prednisolone. The total ophthalmoplegia was markedly improved in one month. Cases of foreign bodies in the orbit with intracranial extension are not unusual, but the path this foreign body traveled through the hard palate without affecting the optic nerve, internal carotid artery or cavernous sinus makes an interesting variation.

  8. Internuclear Ophthalmoplegia Secondary to Cocaine Abuse

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    Richard L. Rabin

    2017-01-01

    Full Text Available Purpose. To report a case of internuclear ophthalmoplegia (INO caused by cocaine. Method. We report a case of a 54-year-old female who presented with a left INO three days after snorting cocaine, and we review the literature. Results. MRI of the brain demonstrated several small abnormal foci in the pons on FLAIR and diffusion weighted imaging consistent with ischemic infarction. The patient’s symptoms remained stable throughout her hospitalization. She was sent to a rehabilitation facility and was lost to follow-up. Conclusion. In cases of extraocular movement abnormalities, it is important to inquire about recreational drug use.

  9. 慢性进行性眼外肌麻痹及Kearns-Sayre综合征患者线粒体DNA突变的研究%Mutation of mitochondrial DNA in patients with chronic progressive external ophthalmoplegia and Kearns-Sayre syndrome

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    田旭; 孙明; 张爽

    2006-01-01

    目的:检测慢性进行性眼外肌麻痹(chronic progressive external ophthalmoplegia, CPEO)及Kearns-Sayre综合征(KSS)患者骨骼肌细胞线粒体DNA的缺失情况.方法:从11例CPEO和KSS患者的骨骼肌活检标本中,提取总体DNA.限制性内切酶PvuⅡ消化1 h,将消化后的DNA片段进行琼脂糖凝胶电泳,使DNA片段按大小分离.用毛细转移法将凝胶上的DNA转移至正电荷尼龙膜上.从正常人全血中提取全长线粒体DNA作为探针,进行地高辛-dUTP标记,并与正电荷尼龙膜进行预杂交、杂交、杂交后冲洗及显色反应.结果:11例中,7例除有一条正常大小杂交带外,还有一条异常的缺失型线粒体DNA杂交带.剂量分析表明,缺失型线粒体DNA占总线粒体DNA的50%~75%.缺失片断在4.5~5.5 kb之间.结论:CPEO及KSS患者骨骼肌线粒体DNA缺失率较高,线粒体DNA基因缺失与线粒体疾病密切相关.

  10. Peripheral neuropathy predicts nuclear gene defect in patients with mitochondrial ophthalmoplegia.

    Science.gov (United States)

    Horga, Alejandro; Pitceathly, Robert D S; Blake, Julian C; Woodward, Catherine E; Zapater, Pedro; Fratter, Carl; Mudanohwo, Ese E; Plant, Gordon T; Houlden, Henry; Sweeney, Mary G; Hanna, Michael G; Reilly, Mary M

    2014-12-01

    Progressive external ophthalmoplegia is a common clinical feature in mitochondrial disease caused by nuclear DNA defects and single, large-scale mitochondrial DNA deletions and is less frequently associated with point mutations of mitochondrial DNA. Peripheral neuropathy is also a frequent manifestation of mitochondrial disease, although its prevalence and characteristics varies considerably among the different syndromes and genetic aetiologies. Based on clinical observations, we systematically investigated whether the presence of peripheral neuropathy could predict the underlying genetic defect in patients with progressive external ophthalmoplegia. We analysed detailed demographic, clinical and neurophysiological data from 116 patients with genetically-defined mitochondrial disease and progressive external ophthalmoplegia. Seventy-eight patients (67%) had a single mitochondrial DNA deletion, 12 (10%) had a point mutation of mitochondrial DNA and 26 (22%) had mutations in either POLG, C10orf2 or RRM2B, or had multiple mitochondrial DNA deletions in muscle without an identified nuclear gene defect. Seventy-seven patients had neurophysiological studies; of these, 16 patients (21%) had a large-fibre peripheral neuropathy. The prevalence of peripheral neuropathy was significantly lower in patients with a single mitochondrial DNA deletion (2%) as compared to those with a point mutation of mitochondrial DNA or with a nuclear DNA defect (44% and 52%, respectively; Pneuropathy as the only independent predictor associated with a nuclear DNA defect (P=0.002; odds ratio 8.43, 95% confidence interval 2.24-31.76). Multinomial logistic regression analysis identified peripheral neuropathy, family history and hearing loss as significant predictors of the genotype, and the same three variables showed the highest performance in genotype classification in a decision tree analysis. Of these variables, peripheral neuropathy had the highest specificity (91%), negative predictive value

  11. BSA adsorption on bimodal PEO brushes

    NARCIS (Netherlands)

    Bosker, W.T.E.; Iakovlev, P.A.; Norde, W.; Cohen Stuart, M.A.

    2005-01-01

    BSA adsorption onto bimodal PEO brushes at a solid surface was measured using optical reflectometry. Bimodal brushes consist of long (N=770) and short (N=48) PEO chains and were prepared on PS surfaces, applying mixtures of PS 29-PEO48 and PS37-PEO770 block copolymers and using the Langmuir-Blodgett

  12. BSA adsorption on bimodal PEO brushes

    NARCIS (Netherlands)

    Bosker, WTE; Iakovlev, PA; Norde, W; Stuart, Martien A. Cohen

    2005-01-01

    BSA adsorption onto bimodal PEO brushes at a solid surface was measured using optical reflectometry. Bimodal brushes consist of long (N = 770) and short (N = 48) PEO chains and were prepared on PS surfaces, applying mixtures of PS29-PEO48 and PS37-PEO770 block copolymers and using the Langmuir-Blodg

  13. Surface grafting thermoresponsive PEO-PPO-PEO chains.

    Science.gov (United States)

    Malal, Ram; Malal, Maya; Cohn, Daniel

    2011-05-01

    The objective of this study was to engineer surfaces comprising covalently bound polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO-PPO-PEO) chains, able to coil and uncoil in aqueous media, as a function of temperature. Thermoresponsive surfaces can be used in diverse areas, such as tissue engineering and 'on-command' drug delivery. The grafting scheme was exemplified using a poly(ethylene terephthalate) (PET) film and started with the exposure of the substrate to plasma of ammonia, whereby amine groups were formed on the film. In the next stage, the amine moieties reacted with the hydroxyterminated thermoresponsive PEO-PPO-PEO triblocks via the hexamethylene diisocyanate (HDI) coupling agent. XPS analysis of the PET film after being exposed to plasma of ammonia revealed substantial amounts of nitrogen, as revealed by the sizeable N1s peak observed at 400.2 eV. A large increase in the C1s ether peak at 286.5 eV was apparent after binding the PEO-PPO-PEO triblocks to the substrate. These findings were confirmed by FTIR spectroscopy and supported by water contact angle measurements. PEO-PPO-PEO triblocks were chain extended by reacting them with HDI, whereby longer polyether urethane chains were formed. The long thermoresponsive chains produced (P-F127) were then tethered to the PET surface, following the procedure used to graft the shorter F127 triblocks. The thermoresponsiveness of the surface was demonstrated by measuring the water contact angle of the P-F127-containing surfaces as a function of temperature.

  14. Recurrent ophthalmoplegia in childhood: diagnostic and etiologic considerations

    Energy Technology Data Exchange (ETDEWEB)

    Oestergaard, J.R.; Moeller, H.U.; Christensen, T.

    1996-06-01

    The authors present two patients with recurrent painful ophthalmoplegia starting in early childhood. Clinically, both patients fulfilled the criteria for ophthalmologic migraine. In one case, magnetic resonance investigations were performed following the second attack, between the third and fourth and during the fourth attack. The left third cranial nerve was significantly thickened in its course from the brainstem through the prepontine cistern to the cavernous sinus during the attacks and moderately thickened between the attacks. In the second case, magnetic resonance imaging was performed during the 14th attack, when the oculomotor nerve dysfunction was almost permanent, and the imaging demonstrated a swollen oculomotor nerve. Whether these finding are pathognomonic of ophthalmoplegic migraine awaits further reports using magnetic resonance imaging in infants showing recurrent painful ophthalmoplegia of eraly onset. 17 refs.

  15. Sensory ataxic neuropathy with dysarthria/dysphagia and ophthalmoplegia (SANDO). Two case reports.

    Science.gov (United States)

    Gáti, István; Danielsson, Olof; Jonasson, Jon; Landtblom, Anne-Marie

    2011-12-01

    Case histories of two unrelated patients suffering from sensory ataxic neuropathy, dysarthria/dysphagia and external ophthalmoplegia (SANDO) are reported. Both patients showed compound heterozygosity for POLG1 gene mutations, and presented with symptom of the clinical characteristics of SANDO. A patient with a p.A467T and p.W748S, well-known mutations showed a progressive course with early onset and multisystem involvement, including symptoms characteristics for mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). The second patient showed a less well-known p.T251I and p.G848S mutations with late onset and dysphagia/dysarthria dominated, moderate symptoms. This later is the second published case history, when these POLG1 gene mutations are the possible background of late onset SANDO, dominantly presenting with bulbar symptoms.

  16. 慢性进行性眼外肌麻痹和 Kearns-Sayre 综合征患者视网膜神经纤维层厚度测量及影响因素分析%Measurement and analysis of retinal nerve fiber layer thickness in chronic progressive external ophthalmoplegia and kearns-sayre syndrome

    Institute of Scientific and Technical Information of China (English)

    吴元; 吴海龙; 王朝霞; 潘英姿; 晏晓明

    2015-01-01

    Objective To determine the retinal nerve fiber layer thickness (RNFLT)of chronic progressive external ophthalmoplegia (CPEO)and kearns-sayre syndrome (KSS)patients using spectral-domain optical coherence tomography (SD-OCT)and to analyze the potential influence factors for RNFLT of these patients.Methods 18 CPEO and 4 KSS (CPEO with retinitis pigmentosa and cardiac block)patients, all were muscle biopsy confirmed,were included in this study.There were 7 males and 1 5 females,the average age was (29.09 ± 13.40)years,the average onset age was (1 6.4 ± 10.7 )years and the average disease duration was (1 1.30 ± 7.30)years.All the patients underwent SD-OCT examination for the left eye,the peripapillary RNFL thickness was measured using the Spectralis 3.45 mm circle scan protocol.8 quadrants were scanned including superior temporal (ST),temporal upper (TU),temporal lower (TL), inferior temporal (IT),inferior nasal (IN),nasal lower (NL),nasal upper (NU)and superior nasal (SN). The relationship between RNFLT and onset time,disease duration was analyzed by Pearson correlation analysis.Results The average RNFLT of ST,TU,TL,IT,IN,NL,NU,SN in the 22 patients were (136.3±24.1),(85.4±25.7),(68.2±1 1.7),(128.2±28.7),(127.3±29.5),(66.7±1 6.8),(70.1± 1 7.6)μm,respectively.The circumferential average RNFLT was (101.5 ± 14.4 )μm.There was no significant difference between the KSS group and CPEO group (P > 0.05 ). The decrease of the circumferential RNFLT had no relationship with the onset age (r = - 0.306,P = 0.1 1 ),but a negative relationship with the disease course (r=-0.5 18,P =0.03).There were negative relationships between the disease course and RNFLT of 4 nasal quadrants (IN:r=-0.555,P =0.01,NL:r=-0.630,P =0.00 NU:r =-0.559,P =0.01,SN:r =-0.557,P =0.01).Conclusion There is no difference in RNFLT of patients with CPEO and KSS.There is a negative relation between RNFLT (especially RNFLT of 4 nasal quadrants)and disease course.%目的:观察慢性

  17. Effect of PEO molecular weight on the miscibility and dynamics in epoxy/PEO blends.

    Science.gov (United States)

    Lu, Shoudong; Zhang, Rongchun; Wang, Xiaoliang; Sun, Pingchuan; Lv, Weifeng; Liu, Qingjie; Jia, Ninghong

    2015-11-01

    In this work, the effect of poly(ethylene oxide) (PEO) molecular weight in blends of epoxy (ER) and PEO on the miscibility, inter-chain weak interactions and local dynamics were systematically investigated by multi-frequency temperature modulation DSC and solid-state NMR techniques. We found that the molecular weight (M(w)) of PEO was a crucial factor in controlling the miscibility, chain dynamics and hydrogen bonding interactions between PEO and ER. A critical PEO molecular weight (M(crit)) around 4.5k was found. PEO was well miscible with ER when the molecular weight was below M(crit), where the chain motion of PEO was restricted due to strong inter-chain hydrogen bonding interactions. However, for the blends with high molecular weight PEO (M(w) > M(crit)), the miscibility between PEO and ER was poor, and most of PEO chains were considerably mobile. Finally, polarization inversion spin exchange at magic angle (PISEMA) solid-state NMR experiment further revealed the different mobility of the PEO in ER/PEO blends with different molecular weight of PEO at molecular level. Based on the DSC and NMR results, a tentative model was proposed to illustrate the miscibility in ER/PEO blends.

  18. Spheniodal mucocele causing bilateral optic neuropathy and ophthalmoplegia

    Directory of Open Access Journals (Sweden)

    Ambika Selvakumar

    2014-01-01

    Full Text Available Sphenoid sinus mucocele comprises only 2% of all paranasal sinus mucoceles. In literature, there is a case report on sphenoidal mucocele causing bilateral optic neuropathy, with unilateral partial recovery and cranial nerve palsy, but we did not come across any literature with bilateral optic neuropathy and ophthalmoplegia together caused by spheno-ethmoidal mucocele. We present such a rare case of spheno-ethmoidal mucocele causing bilateral optic neuropathy and unilateral sixth nerve palsy who had postsurgery, unilateral good vision recovery, and complete resolution of sixth nerve palsy.

  19. Bilateral ophthalmoplegia and exophthalmos complicating central hemodialysis catheter placement.

    Science.gov (United States)

    Varelas, P N; Bertorini, T E; Halford, H

    1999-05-01

    We describe a 58-year-old woman who presented with bilateral ophthalmoplegia, exophthalmos, and headache and was found to have retrograde internal jugular vein flow secondary to a high-grade obstruction of the ipsilateral brachiocephalic vein from a previous hemodialysis catheter placement. The patient had also a high-flow dialysis graft in the ipsilateral arm. The cranial and extracranial venous system congestion resolved, and the signs disappeared soon after a balloon angioplasty and stent placement at the level of the obstruction.

  20. Spheniodal mucocele causing bilateral optic neuropathy and ophthalmoplegia.

    Science.gov (United States)

    Selvakumar, Ambika; Mahalaxmi, Balasubramanyam; Ananth, V; Gautam, Cugati

    2014-04-01

    Sphenoid sinus mucocele comprises only 2% of all paranasal sinus mucoceles. In literature, there is a case report on sphenoidal mucocele causing bilateral optic neuropathy, with unilateral partial recovery and cranial nerve palsy, but we did not come across any literature with bilateral optic neuropathy and ophthalmoplegia together caused by spheno-ethmoidal mucocele. We present such a rare case of spheno-ethmoidal mucocele causing bilateral optic neuropathy and unilateral sixth nerve palsy who had postsurgery, unilateral good vision recovery, and complete resolution of sixth nerve palsy.

  1. Effects of PEO-PPO diblock impurities on the cubic structure of aqueous PEO-PPO-PEO pluronics micelles: fcc and bcc ordered structures in F127

    DEFF Research Database (Denmark)

    Mortensen, Kell; Pedersen, Walther Batsberg; Hvidt, S.

    2008-01-01

    We report on structural properties of PEO-PPO-PEO type of triblock block copolymers (Pluronics F127) with special emphasis on the effect of diblock PEO-PPO impurities on the ordered gel phase. Commercial F127 polymers contain as received roughly 20% PEO-PPO diblock and 80% PEO-PPO-PEO triblock...... copolymers. Aqueous solutions of F127 copolymers used as received form fee ordered micellar structure. Copolymers depleted with respect to the diblock impurity, resulting in a pure PEO-PPO-PEO triblock copolymer system, form bcc ordered micelles within the major parts of the gel phase. However, close...

  2. Bilateral internuclear ophthalmoplegia as first manifestation of extra pontine myelinolysis

    Directory of Open Access Journals (Sweden)

    Tushar Kanti Bandyopadhyay, Rudrajit Paul, Amit K Das, Rathindranath Sarkar

    2014-07-01

    Full Text Available Extrapontine myelinolysis (EPM is a rare clinical entity affecting anterior basal ganglia. This is one of the osmotic demyelination syndromes. It occurs due to rapid correction of hyponatremia and also rarely occurs in alcoholics. It generally presents with extrapyramidal symptoms. We here report a case of EPM in a 13 year old boy presenting with bilateral internuclear ophthalmoplegia and ptosis. The patient also had generalised weakness, but no psychiatric symptoms. The patient slowly recovered over six months. EPM can affect any age group, although the elderly are more likely to be affected due to frequent electrolyte abnormalities. Ocular movement disorders or brainstem signs are rarely reported in EPM. When present, it can create diagnostic confusion with multiple sclerosis. We believe this is the first report of this entity from India. The relevant literature regarding brainstem manifestations in myelinolysis syndromes is also discussed, along with the radiological findings.

  3. [Preparation and characterization of irinotecan hydrochloride loaded PEO-PPO-PEO micelles and its mechanism of decreasing drug intestinal toxicity].

    Science.gov (United States)

    Zhang, Xin-Xin; Guo, Shi-Yan; Li, Fei-Fei; Gan, Yong

    2012-11-01

    In this work, we developed PEO-PPO-PEO micelles loaded with irinotecan hydrochloride (CPT-11) using breast cancer resistance protein (BCRP) inhibitory material PEO20-PPO70-PEO20, and studied its mechanism of decreasing CPT-11 induced delayed diarrhea and intestinal toxicity. BCRP-overexpressing MDCKII (MDCKII/BCRP) cells were used to evaluate the effect of PEO20-PPO70-PEO20 and PEO-PPO-PEO micelles on transmembrane transport of CPT-11 in vitro. The biliary excretion, delayed diarrhea and intestinal damage of CPT-11 loaded PEO-PPO-PEO micelles of rats were investigated. The results showed that the obtained micelles could decrease the biliary excretion of CPT-11, ameliorate delayed diarrhea and intestinal toxicity of rats through inhibiting BCRP-mediated CPT-11 efflux. PEO-PPO-PEO micelles were promising carriers to reduce intestinal toxicity of CPTs.

  4. Cogan’s anterior internuclear ophthalmoplegia in young Ethiopian

    African Journals Online (AJOL)

    Yeshigeta Gelaw

    2014-06-16

    Jun 16, 2014 ... a rare clinical spectrum of internuclear ophthalmoplegia called Cogan's anterior internuclear ... systemic lupus erythematosus.1–5. To the best of the author's ... neurological symptoms and no family history of known neuro-.

  5. Muscle fiber hypotrophy with intact neuromuscular junctions. A study of a patient with congenital neuromuscular disease and ophthalmoplegia.

    Science.gov (United States)

    Bender, A N; Bender, M B

    1977-03-01

    An infant born with severe but nonprogressive somatic and cranial muscle weakness including bilateral external ophthalmoplegia was studied with a motor-point muscle biopsy. There was a strinking generalized decrease in the size of muscle fibers (hypotrophy), most marked in the type I fibers. Many of the small fibers were immature, resembling myotubes. Neuromuscular junctions on severely hypotrophic fibers were normal with esterase staining and by ultrastructural criteria. Although these are unusual clinical and biopsy characteristics, this infant's condition bears a resemblance to two other congenital nonprogressive neuromuscular diseases:myotubular myopathy and congenital fiber type disproportion. In these conditions and in our patient, there is no primary degenerative process affecting nerve or muscle but, rather, an apparent lack of maturation of fetal muscle fibers, indicating a defective normal trophic interaction between nerve and muscle.

  6. Interaction between PEO-PPO-PEO copolymers and a hexapeptide in aqueous solutions.

    Science.gov (United States)

    Jia, Lianwei; Guo, Chen; Xiang, Junfeng; Wang, Ning; Yang, Liangrong; Tang, Yalin; Liu, Huizhou

    2012-01-24

    Interaction between PEO-PPO-PEO copolymers and a hexapeptide, growth hormone releasing peptide-6 (GHRP-6), was investigated by NMR to study the potential use of the copolymers in peptide drug delivery. (1)H NMR and nuclear Overhauser effect spectroscopy (NOESY) measurements determined that PO methyl protons interacted with methyl protons of the Ala moiety, aromatic protons of the Trp moiety, and some of the Phe aromatic protons. The Lys moiety and part of the Phe moiety entered the hydrophilic EO environment via hydrogen bonding. PEO-PPO-PEO copolymers and the peptide formed a complex in 1:1 stoichiometry. Binding constants between copolymers and GHRP-6 were determined, and it was indicated that the copolymers containing more EO and PO units will lead to greater affinity with the peptide. Isothermal titration calorimetry (ITC) measurements confirmed the results of NMR experiments. This study indicates that PEO-PPO-PEO copolymers have great potential in delivering peptide drugs.

  7. Ocular vestibular evoked myogenic potentials are abnormal in internuclear ophthalmoplegia.

    Science.gov (United States)

    Rosengren, S M; Colebatch, J G

    2011-06-01

    The cervical vestibular evoked myogenic potential (cVEMP) is sensitive to lower brainstem lesions affecting the vestibulo-collic pathway. We wished to determine whether the ocular VEMP (oVEMP), a recently-described otolith-ocular reflex, is also abnormal in patients with brainstem lesions. We tested patients with internuclear ophthalmoplegia (INO), caused by a brainstem lesion in the medial longitudinal fasciculus (MLF), to investigate whether the oVEMP is abnormal in patients with a lesion of the otolith-ocular pathway. We describe a patient who developed a right INO during his first episode of demyelination, and report results from 12 additional patients, most of whom had multiple sclerosis. All subjects were stimulated with air-conducted tone bursts. cVEMPs and oVEMPs were measured using surface electrodes placed over the neck and beneath the eyes. Overall, oVEMPs showed significantly more abnormalities (69%) than cVEMPs (8%). Ocular VEMPs were absent with stimulation of 13/26 ears, significantly delayed in 5/26 cases and normal in only 8/26 cases. Ocular VEMPs are often abnormal in patients with multiple sclerosis who have an INO, while cVEMPs are usually normal. Ocular VEMPs provide a new, non-invasive method for examining central vestibular pathways in humans and are sensitive to lesions of the MLF. Copyright © 2010 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  8. Neurofibromatosis Type 2 Presenting with Oculomotor Ophthalmoplegia and Distal Myopathy

    Directory of Open Access Journals (Sweden)

    Jessica Mani Penny Tevaraj

    2016-01-01

    Full Text Available Neurofibromatosis type 2 usually presents with bilateral acoustic schwannomas. We highlight the rare presentation of neurofibromatosis initially involving third nerve. A 23-year-old Malay female presented with left eye drooping of the upper lid and limitation of upward movement for 8 years. It was associated with right-sided body weakness, change in voice, and hearing disturbance in the right ear for the past 2 years. On examination, there was mild ptosis and limitation of movement superiorly in the left eye. Both eyes had posterior subcapsular cataract. Fundoscopy showed generalised optic disc swelling in both eyes. She also had palsy of the right vocal cord, as well as the third and eighth nerve. There was wasting of the distal muscles of her right hand, with right-sided decreased muscle power. Pedunculated cutaneous lesions were noted over her body and scalp. MRI revealed bilateral acoustic and trigeminal schwannomas with multiple extra-axial lesions and intradural extramedullary nodules. Patient was diagnosed with neurofibromatosis type 2 and planned for craniotomy and tumour debulking, but she declined treatment. Neurofibromatosis type 2 may uncommonly present with isolated ophthalmoplegia, so a thorough physical examination and a high index of suspicion are required to avoid missing this condition.

  9. Aggregation behaviors of PEO-PPO-ph-PPO-PEO and PPO-PEO-ph-PEO-PPO at an air/water interface: experimental study and molecular dynamics simulation.

    Science.gov (United States)

    Gong, Houjian; Xu, Guiying; Liu, Teng; Xu, Long; Zhai, Xueru; Zhang, Jian; Lv, Xin

    2012-09-25

    The block polyethers PEO-PPO-ph-PPO-PEO (BPE) and PPO-PEO-ph-PEO-PPO (BEP) are synthesized by anionic polymerization using bisphenol A as initiator. Compared with Pluronic P123, the aggregation behaviors of BPE and BEP at an air/water interface are investigated by the surface tension and dilational viscoelasticity. The molecular construction can influence the efficiency and effectiveness of block polyethers in decreasing surface tension. BPE has the most efficient ability to decrease surface tension of water among the three block polyethers. The maximum surface excess concentration (Γ(max)) of BPE is larger than that of BEP or P123. Moreover, the dilational modulus of BPE is almost the same as that of P123, but much larger than that of BEP. The molecular dynamics simulation provides the conformational variations of block polyethers at the air/water interface.

  10. A case of polymyositis with ophthalmoplegia Laboratory examinations

    Institute of Scientific and Technical Information of China (English)

    Shunchang Han; Chuanqiang Pu; Xusheng Huang; Senyang Lang; Weiping Wu

    2008-01-01

    OBJECTIVE: Polymyositis (PM) mainly involves proximal limb and trunk muscles. Ocular muscles are not affected, except in rare cases with both PM and myasthenia gravis (MG). Thus, the results of laboratory examinations in such a patient deserve to be reported.METHODS: To analyze the clinical, imaging and pathology datas on a 65-year-old woman patient with PM with complex symptoms, who presented mainly ophthalmoplegia. The patient consented to all examinations and the hospital Ethics Committee approved the study. The laboratory examinations included creatine kinase (CK), ENA, tumor marker, function of thyroid, cranial MRI, and electromyogram (EMG). Biopsy of the left quadriceps femoris was performed, frozen specimens were stained with hematoxylin and eosin, ATPase, NADH tetrazolium reductase, periodic acid Schiff, oil red O, modified Gomory trichrome and MHC-I, to investigate the pathology of muscle fibersRESULTS: Laboratory results showed: CK, 108.32μkat/L; antinuclear antibody: (+); ENA, (-); tumor marker, (-); normal thyroid function, MRI showed no abnormal signals in brain and extraocular muscles. Electromyography of the bilateral deltoid, biceps brachii, musculus quadriceps fexoris, anterior tibialis showed fibrillation potentials, positive potentials and short-duration, small-amplitude polyphasic potentials on voluntary movements with a full interference pattern on mild exertion. Repetitive stimulation did not result in any increment or decrement in these potentials. A muscle biopsy of the left quadriceps femoris showed many small round muscle fibers without peripheral bundle distribution and apparent myofiber degeneration, necrosis and phagocytosis. There were several focal lymphocyte infiltrations. MHC-I immunohistochemical staining was positive in most fibers revealing inflammatory infiltration of normal fibers with MHC-I expression. CONCLUSION: This patient showed increased CK, typical triad of myopathy in EMG, and apparent degeneration and necrosis in

  11. Electrorheological Properties of Suspensions of PAn-PEO-PAn Triblock Copolymer Particles

    Institute of Scientific and Technical Information of China (English)

    MA Huiru; GUAN Jianguo; YUAN Runzhang

    2005-01-01

    The PAn-PEO-PAn triblock copolymer with the PEG chain length of 400 was synthesized by chemical oxidation copolymerization of aniline and α, ω- bis ( p- aminophenyl ) poly ( ethylene glycol ) and characterized by FT-IR and TEM. The experimental results show that the copolymer particles are of a typical core-shell structure after the self-assembly process in water. Its conductivity is much lower than that of the pure PAn. The suspension containing 20 vol% PAn-PEO-PAn triblock copolymer in silicone oil exhibits a typical electrorheological ( ER ) effect in DC electric field, while it shows a lower leakage current density than that of the pure PAn- based ER fluids. Therefore, the PEO shell hinders the electric hop among PANI chains and decreases the current density of ER fluids in an external electric field, at the same time the interface polarity improves the ER effects.

  12. Analysis of single-nucleotide polymorphisms of PEO1 gene in 55 ethnic groups of India

    Directory of Open Access Journals (Sweden)

    Ashok Singh

    2012-01-01

    Full Text Available Background: Progressive External Opthalmoplegia (PEO1 or Chromosome 10 open reading frame 2 gene (OMIM ID 606075 encodes Twinkle protein, a phage T7 gene 4-like hexameric helicase, and is associated with mitochondrial DNA (mtDNA deletions and neuromuscular disease called autosomal dominant PEO (adPEO. Twinkle has also been known to play an important role in the stability and maintenance of the mtDNA. Aims: In this study as an effort of Indian Genome Variation Consortium, we screened the SNPs of PEO1 gene such as rs7184, rs1535349, rs2863095, rs3740484, rs3740488, rs3740489, rs4919511, rs17113613, rs3824783, rs3740485, rs3740486, and rs3740487 in discovery panel (a population set of 40 DNA samples, and four synonymous SNPs, namely rs3824783 (ancestral allele=A, rs3740485 (ancestral allele=T, rs3740486 (ancestral allele=C, and rs3740487 (ancestral allele=A in a large validation panel composed of 55 Indian subpopulations. Materials and Methods: In present study, a total of 55 Indian subpopulations were identified and collected for validation panel to check the frequencies of SNPs in PEO1 gene. Results and Conclusion: The allelic and genotype frequencies are found to be variable among different ethnic groups of India.

  13. 痛性眼肌麻痹伴急性鼻窦炎1例%One patient with painful ophthalmoplegia and acute rhinosinusitis

    Institute of Scientific and Technical Information of China (English)

    李戍军; 薛明学; 孙波

    2012-01-01

    Summary By analyzing the diagnosis and treatment of a patient who suffered from painful ophthalmoplegia and acute rhinosinusitis, authors further identified the clinical features of painful ophthalmoplegia, and the differential diagnosis of those diseases which might cause migraine and ophthalmoplegia to avoid clinical misdiagnosis and mistreatment.

  14. Polymer-polymer miscibility in PEO/cationic starch and PEO/hydrophobic starch blends

    Directory of Open Access Journals (Sweden)

    2010-08-01

    Full Text Available The main purposes were evaluating the influence of different starches on the miscibility with Poly(ethylene oxide (PEO and their effects on the spherulite growth rate. Polymer-polymer miscibility in PEO/cationic starch and PEO/hydrophobic starch blends consisting of different w/w ratios (100/0, 95/05, 90/10, 80/20, 70/30, 65/35 and 60/40 was investigated. This analysis was based on the depression in the equilibrium melting temperature (Tm0. By treating the data of thermal analysis (Differential Scanning Calorimetry – DSC with Nishi-Wang equation, a positive value (0.68 was found for the interaction parameter of PEO/cationic starch. For PEO/hydrophobic starch blends, a negative value (–0.63 was obtained for the interaction parameter. The results suggested that PEO/cationic starch system should be immiscible. However, the system PEO/hydrophobic starch was considered to be miscible in the whole range of studied compositions. Through optical microscopy analysis, it was concluded that the spherulite growth rate is significantly affected by changing the amount and the type of starch as well.

  15. Electron microscopic study on aerosol-assisted synthesis of aluminum organophosphonates using flexible colloidal PS-b-PEO templates.

    Science.gov (United States)

    Kimura, Tatsuo; Yamauchi, Yusuke

    2012-09-04

    A wide variety of synthetic approaches from homogeneous precursor solutions have so far been developed for precise structural design of materials in multiscale. In organic templating approaches for porous materials design, we have recently developed a new approach to fabricate colloidal polystyrene-block-poly(oxyethylene) (PS-b-PEO) templated large pores that can be controlled in thick films of aluminum organophosphonate (AOP). In this study, we extended this approach using colloidal PS-b-PEO aggregates to aerosol-assisted synthesis for the fabrication of spherical particles. Structural variations (morphology and porous structure) depended on the synthetic conditions, which were mainly investigated by using electron microscopies (SEM and TEM). In addition to the insight on the colloidal PS-b-PEO templating of spherical pores in AOP spheres, it was found that colloidal PS-b-PEO aggregates were flexible for further design of pore shape that was strongly affected by external morphology. In this context, we proposed this method as flexible colloidal PS-b-PEO templating to fabricate unusual macroporous structures during morphological control from precursor solutions containing colloidal PS-b-PEO aggregates. The insights will be promising for precise construction of unique devices using porous materials templated by colloidal organic aggregates. In addition, we found a useful water adsorption-desorption behavior over the macroporous AOP bulky powders when the macropores were connected through large pores, which is also significant for future development of AOP-based porous materials.

  16. Effects of PEO-PPO-PEO triblock copolymers on phospholipid membrane integrity under osmotic stress.

    Science.gov (United States)

    Wang, Jia-Yu; Chin, Jaemin; Marks, Jeremy D; Lee, Ka Yee C

    2010-08-03

    The effects of PEO-PPO-PEO triblock copolymers, mainly Poloxamer 188, on phospholipid membrane integrity under osmotic gradients were explored using giant unilamellar vesicles (GUVs). Fluorescence leakage assays showed two opposing effects of P188 on the structural integrity of GUVs depending on the duration of their incubation time. A two-state transition mechanism of interaction between the triblock copolymers and the phospholipid membrane is proposed: an adsorption (I) and an insertion (II) state. While the triblock copolymer in state I acts to moderately retard the leakage, their insertion in state II perturbs the lipid packing, thus increasing the membrane permeability. Our results suggest that the biomedical application of PEO-PPO-PEO triblock copolymers, either as cell membrane resealing agents or as accelerators for drug delivery, is directed by the delicate balance between these two states.

  17. Synthesis and characterization of fluorinated PEO-b-PDMS-b-fluorinated PEO by free radical addition

    Institute of Scientific and Technical Information of China (English)

    Wei Hu Li; Xing Yuan Zhang; Jia Bing Dai

    2009-01-01

    Fluorinated poly(ethylene oxide)propyl-b-polydimethylsiloxane-b-propyl fluorinated poly(ethylene oxide)(FPEO-b-PDMS-b-FPEO)was synthesized by a free radical addition of carbon-hydrogen of polyether segments of poly(ethylene oxide)propyl-b-polydimethylsiloxane-b-propyl poly(ethylene oxide)(PEO-b-PDMS-b-PEO)to hexafluoropropylene(HFP)using rert-butyl peroxypivalate as an initiator.In order to reduce the possibility of side reaction,the protection and deprotection via silylation were used for the end-hydroxyls in PEO-b-PDMS-b-PEO chain.The structure of Intermediates and FPEO-b-PDMS-b-FPEO was confirmed by means of Fourier transform infrared and 1H NMR spectroscopy.The effects of amount of initiator,reaction temperature and time on free radical addition were investigated in detail.

  18. Enhancing the protein resistance of silicone via surface-restructuring PEO-silane amphiphiles with variable PEO length.

    Science.gov (United States)

    Rufin, M A; Gruetzner, J A; Hurley, M J; Hawkins, M L; Raymond, E S; Raymond, J E; Grunlan, M A

    2015-04-14

    Silicones with superior protein resistance were produced by bulk-modification with poly(ethylene oxide) (PEO)-silane amphiphiles that demonstrated a higher capacity to restructure to the surface-water interface versus conventional non-amphiphilic PEO-silanes. The PEO-silane amphiphiles were prepared with a single siloxane tether length but variable PEO segment lengths: α-(EtO)3Si(CH2)2-oligodimethylsiloxane13-block-poly(ethylene oxide) n -OCH3 (n = 3, 8, and 16). Conventional PEO-silane analogues (n = 3, 8 and 16) as well as a siloxane tether-silane (i.e. no PEO segment) were prepared as controls. When surface-grafted onto silicon wafer, PEO-silane amphiphiles produced surfaces that were more hydrophobic and thus more adherent towards fibrinogen versus the corresponding PEO-silane. However, when blended into a silicone, PEO-silane amphiphiles exhibited rapid restructuring to the surface-water interface and excellent protein resistance whereas the PEO-silanes did not. Silicones modified with PEO-silane amphiphiles of PEO segment lengths n = 8 and 16 achieved the highest protein resistance.

  19. Synthesis and characterization of a novel hydroxypolyether blocked polydimethylsiloxane PEO-b-PDMS-b-PEO

    Institute of Scientific and Technical Information of China (English)

    Wei Hu Li; Xing Yuan Zhang; Jia Bing Dai

    2008-01-01

    A novel hydroxypolyether blocked polydimethylsiloxane,poly(ethylene oxide)propyl-b-polydimethylsiloxane-b-propyl poly(ethylene oxide)(PEO-b=PDMS-b-PEO)was synthesized by simple hydrosilation reaction of poly(ethylene glycol)monoallyl ether with α,ω-dihydrogen terminated PDMS(HPDMS).Fourier transform infrared spectroscopy(FTIR)and 1H NMR were used to identify the structure of PEO-b-PDMS-b-PEO and intermediate product HPDMS.Based on the effect investigations of temperature.reactant molar ratio,catalyst and time on the hydrosilation,it Was found that the conversion of Si-H bond to Si-C bond increased with the increase of catalyst and time,and the reaction completed when the content of catalyst Was 22 μg/g and the time Was 5 h,respectively.Urethane reaction of OH and NCO group confirms that PEO-b-PDMS-b-PEO is more reactive toward to diisocyanate than α,ω-dihydroxylbutyl terminated PDMS.

  20. Comprehensive characterization of chitosan/PEO/levan ternary blend films.

    Science.gov (United States)

    Bostan, Muge Sennaroglu; Mutlu, Esra Cansever; Kazak, Hande; Sinan Keskin, S; Oner, Ebru Toksoy; Eroglu, Mehmet S

    2014-02-15

    Ternary blend films of chitosan, PEO (300,000) and levan were prepared by solution casting method and their phase behavior, miscibility, thermal and mechanical properties as well as their surface energy and morphology were characterized by different techniques. FT-IR analyses of blend films indicated intermolecular hydrogen bonding between blend components. Thermal and XRD analysis showed that chitosan and levan suppressed the crystallinity of PEO up to nearly 25% of PEO content in the blend, which resulted in more amorphous film structures at higher PEO/(chitosan+levan) ratios. At more than 30% of PEO concentration, contact angle (CA) measurements showed a surface enrichment of PEO whereas at lower PEO concentrations, chitosan and levan were enriched on the surfaces leading to more amorphous and homogenous surfaces. This result was further confirmed by atomic force microscopy (AFM) images. Cell proliferation and viability assay established the high biocompatibility of the blend films.

  1. Enhancing the protein resistance of silicone via surface-restructuring PEO-silane amphiphiles with variable PEO length

    OpenAIRE

    Rufin, M. A.; Gruetzner, J. A.; Hurley, M. J.; Hawkins, M. L.; Raymond, E. S.; Raymond, J. E.; Grunlan, M. A.

    2015-01-01

    Silicones with superior protein resistance were produced by bulk-modification with poly(ethylene oxide) (PEO)-silane amphiphiles that demonstrated a higher capacity to restructure to the surface-water interface versus conventional non-amphiphilic PEO-silanes. The PEO-silane amphiphiles were prepared with a single siloxane tether length but variable PEO segment lengths: α-(EtO)3Si(CH2)2-oligodimethylsiloxane13-block-poly(ethylene oxide)n-OCH3 (n = 3, 8, and 16). Conventional PEO-silane analogu...

  2. Mid-term evaluation of the Climate Change Action Fund : Public education and outreach (PEO) Block

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-11-01

    In February 1998, the Government of Canada established the Climate Change Action Fund (CCAF) to assist Canada in meeting its commitments under the Kyoto Protocol for the reduction of greenhouse gas emissions. The CCAF managed a budget of 150 million dollars over three years, and the Public Education and Outreach (PEO) Block was allocated 30 million dollars of that total for its operations. Its mandate was to increase public awareness and understanding on the topic of climate change, as well as providing the required information to effect reductions in the emissions of greenhouse gases and adapt to climate change. An evaluation into this program was conducted, and it covered the period September 2000 to January 20, 2001. To date, 152 projects have been approved, which represents an investment of approximately 17.5 million dollars. Approximately 6 million dollars have been spent on the awareness component, while government communication activities used approximately 3.1 million dollars. Staff and project management fees in support of the program account for the remaining funds. This report addressed the performance to date in meeting the objectives, and also included recommendations for improved effectiveness. PEO files and records, a report entitled Interim review of the Climate Change Action Fund PEO Program, interviews with Departmental representatives, and interviews with external stakeholder groups formed the basis for the findings and recommendations. It was determined that future direction represents the most critical issue facing the PEO block. 1 tab.

  3. Thermochromism and fluorescence in dyed PEO films

    Energy Technology Data Exchange (ETDEWEB)

    Kamath, Archana; S, Raghu; V, Mini; C, Sharanappa; H, Devendrappa, E-mail: dehu2010@gmail.com [Dept. of Physics, Mangalore University, Managalagangothri, Mangalore--574199 (India)

    2015-06-24

    The optical absorbance spectra of solution casted pure & methyl blue (MB) dyed polyethylene oxide (PEO) films were recorded in a wavelength range from 190-1100nm at different temperatures. The absorbance was found to increases with increasing temperature. Fluorescence micrographs confirmed the interaction between polymer and dye and also revealed decreased crystallinity of the sample. Fluorescence quantum yield has been calculated with the help of fluorescence spectra.

  4. Homopolyrotaxanes and Homopolyrotaxane Networks of PEO

    Science.gov (United States)

    Pugh, Coleen; Mattice, Wayne

    2005-01-01

    In order to identify the optimum size of macrocrown ether for threading, we first investigated the size and shape of simple crown ethers in the melt at 373 K, and their extent of threading with PEO in the melt using coarse-grained Monte Carlo simulations on the 2nnd (second nearest neighbor diamond) lattice, which is a high coordination lattice whose coarse-grained chains can be reverse mapped into fully atomistic models in continuous space.

  5. Wetting of Hydrophilic Electrospun Mats Produced by Blending SEBS with PEO-PPO-PEO Copolymers of Different Molecular Weight.

    Science.gov (United States)

    Kurusu, Rafael S; Demarquette, Nicole R

    2016-02-23

    The interaction of electrospun mats with water is critical for many possible applications, and the water contact angle on the surface is the parameter usually measured to characterize wetting. Although useful for hydrophobic surfaces, this approach is limited for hydrophilic mats, where wicking also has to be considered. In this case, it is still unclear how the fiber surface chemical composition and morphology will affect the wetting behavior of electrospun mats. In this work, wetting was studied with different hydrophilic membranes produced by blending thermoplastic elastomer poly(styrene)-b-poly(ethylene-butylene)-b-poly(styrene) (SEBS) with amphiphilic poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (PEO-PPO-PEO) molecules. Three different types of PEO-PPO-PEO, with different molar masses, PEO content, and physical form were used. The effect of these differences on the wetting behavior of the electrospun mats was evaluated by contact angle goniometry, wicking measurements, and different imaging techniques. X-ray photoelectron spectroscopy was used to characterize the surface chemical composition. The smaller molecules quickly saturated the surface at low concentrations, making the mats hydrophilic. The sheath of PEO-PPO-PEO also resulted in fast absorption of water, when comparing the saturated and nonsaturated surfaces. Longer PEO chain-ends seemed to hinder complete segregation and also led to a higher activation time when in contact with water. Liquid PEO-PPO-PEO was easily leached by water.

  6. Dissipative particle dynamics simulation on paclitaxel loaded PEO-PPO-PEO block copolymer micelles.

    Science.gov (United States)

    Wang, Zhigao; Jiang, Jie

    2014-03-01

    Self-assembly behavior of the polymer drug loading micelle PEO-PPO-PEO was studied using dissipative particle dynamics (DPD) simulation method with various simulation steps. The distributions of drugs in polymer carriers were also investigated with different drug feed ratios. Polymer carriers distributed on the surface of the spherical micelle, and drugs were almost encapsulated in the inner of the micelle. Our simulation work demonstrates that the DPD simulation is effective to study the drug loaded systems and can give useful guidance on the design and preparation of new drug carriers with tailored properties.

  7. Solution behavior of PEO : the ultimate biocompatible polymer.

    Energy Technology Data Exchange (ETDEWEB)

    Curro, John G.; Frischknecht, Amalie Lucile

    2004-11-01

    Poly(ethylene oxide) (PEO) is the quintessential biocompatible polymer. Due to its ability to form hydrogen bonds, it is soluble in water, and yet is uncharged and relatively inert. It is being investigated for use in a wide range of biomedical and biotechnical applications, including the prevention of protein adhesion (biofouling), controlled drug delivery, and tissue scaffolds. PEO has also been proposed for use in novel polymer hydrogel nanocomposites with superior mechanical properties. However, the phase behavior of PEO in water is highly anomalous and is not addressed by current theories of polymer solutions. The effective interactions between PEO and water are very concentration dependent, unlike other polymer/solvent systems, due to water-water and water-PEO hydrogen bonds. An understanding of this anomalous behavior requires a careful examination of PEO liquids and solutions on the molecular level. We performed massively parallel molecular dynamics simulations and self-consistent Polymer Reference Interaction Site Model (PRISM) calculations on PEO liquids. We also initiated MD studies on PEO/water solutions with and without an applied electric field. This work is summarized in three parts devoted to: (1) A comparison of MD simulations, theory and experiment on PEO liquids; (2) The implementation of water potentials into the LAMMPS MD code; and (3) A theoretical analysis of the effect of an applied electric field on the phase diagram of polymer solutions.

  8. Effects of PEO Content on the Morphological Behavior of PS-PI-PEO Triblock Copolymers

    Science.gov (United States)

    Bailey, Travis S.; Bates, Frank S.

    2000-03-01

    Many studies involving ABC triblock copolymers have focused on the unique morphologies that particular molecules or blends express. However, investigations of thermally induced morphological changes in these molecules have been limited. A series of poly(styrene-isoprene-ethyleneoxide) ABC-triblock copolymers were sythesized with increasing PEO content. Consistency among all triblocks was achieved through ethylene oxide addition to the same hydroxy-functionalized poly(styrene-isoprene) diblock (MW = 18000g/mol, vol. frac. PS =0.5). Final triblock PEO volume fractions ranged from 0.029 to 0.207. All triblocks in the series showed order-to-disorder transitions (ODTs), ranging from 84C to 215C. Interestingly, initial addition of PEO resulted in a marked depression of the ODT relative to the parent diblock (116C). Characterization of these triblocks, using a combination of techniques including reology, SAXS, and TEM, shows multiple changes in morphology over the range of compositions studied, as well as possible order-to-order transitions (OOTs) associated with triblocks of specific compositions. Progression of these morphological changes with increasing PEO content will be discussed.

  9. Alginate/PEO-PPO-PEO composite hydrogels with thermally-active plasticity.

    Science.gov (United States)

    White, Joseph C; Saffer, Erika M; Bhatia, Surita R

    2013-12-09

    Stimuli-responsive hydrogels with high strength and toughness have received significant interest in recent years. Here, we report thermally active composite hydrogels comprising alginate and one of two poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymers. Temperature-sensitive structural and mechanical changes are probed using calorimetry, neutron scattering, shear rheology, unconfined compression, and fracture. Below the lower gelation temperature, LGT, the mechanical properties are dominated by alginate. As the LGT is reached, the contribution of PEO-PPO-PEO to the mechanical properties is activated, resulting in order-of-magnitude increases in elastic modulus. Under compression, we show the evolution of plasticity for the composite hydrogels as the LGT is approached and surpassed, resulting in dramatic increases in fracture stress compared to neat alginate hydrogels. Plasticity was observed above the LGT and may be attributed to restructuring from the sliding of packed micelles and strain-hardening due to stress concentration on alginate cross-links and junction zones, ultimately leading to fracture.

  10. Phase Diagrams for the PEO-LiX Electrolyte System.

    Science.gov (United States)

    1987-01-01

    rather flat, in sharp contrast to previous results. 3.2c PEO- LiBF4 System Pure PEO forms complexes with LiBF , and the subsequent phase diagram for...study; 0 ----NMR(15); 0 -DSC or DTA(7, 10,12); A ---a.c.conductivity(6,10,12); 4- optical microscopy(6). is 350 - (PEO) n- LiBF4 300 (PEO) n-LiCF 3SO 3...the PEO- LiBF4 system IS" , " ATOM RATIO O/Li 50 25 8 4 2 1 250 200 150 1 00 -50I 0 0 0.1 0.2 0.3 0.4 0.5 XLiPF6 -’+’ Figure 6. Phase diagram of the

  11. Vincristine-Induced Neuropathy Presenting as Ptosis and Ophthalmoplegia in a 2-Year-Old Boy.

    Science.gov (United States)

    Palkar, Amit H; Nair, Akshay Gopinathan; Desai, Roshani J; Potdar, Nayana A; Shinde, Chhaya A

    2015-07-07

    Vincristine is used in the treatment of leukemias, solid tumors, and lymphomas. A case of a 2-year-old boy undergoing treatment for leukemia who developed sudden onset bilateral ptosis and ophthalmoplegia along with generalized neuropathy due to vincristine's neurotoxic effects is presented. He was successfully treated with pyridoxine and pyridostigmine. The possible mechanisms of action and the treatment for vincristine-induced neuropathy are discussed. Prompt treatment and close follow-up is needed, especially in children because prolonged ptosis and motility restriction may have a profound effect on a child's visual function.

  12. Supramolecular hydrogels based on self-assembly between PEO-PPO-PEO triblock copolymers and alpha-cyclodextrin.

    Science.gov (United States)

    Ni, Xiping; Cheng, Alan; Li, Jun

    2009-03-15

    This article reports a detailed study on the hydrogel formation of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymers with alpha-cyclodextrin (alpha-CD) in aqueous solutions. The gelation kinetics and the gel rheological properties were studied using viscometry. The sol-gel phase transitions were studied using phase diagrams, while the gelation mechanism was studied using differential scanning calorimetric analysis. It was concluded that the gelation was induced by the complex formation between the PEO segments of the PEO-PPO-PEO triblock copolymer and alpha-CD, and the further self-assembly of the partially formed inclusion complexes. The addition of alpha-CD largely reduced the concentration of the copolymer needed for gel formation. The gels were thixotropic and reversible, and potentially suitable for use as an injectable drug-delivery system.

  13. adPEO mutations in ANT1 impair ADP-ATP translocation in muscle mitochondria.

    Science.gov (United States)

    Kawamata, Hibiki; Tiranti, Valeria; Magrané, Jordi; Chinopoulos, Christos; Manfredi, Giovanni

    2011-08-01

    Mutations in the heart and muscle isoform of adenine nucleotide translocator 1 (ANT1) are associated with autosomal-dominant progressive external opthalmoplegia (adPEO) clinically characterized by exercise intolerance, ptosis and muscle weakness. The pathogenic mechanisms underlying the mitochondrial myopathy caused by ANT1 mutations remain largely unknown. In yeast, expression of ANT1 carrying mutations corresponding to the human adPEO ones causes a wide range of mitochondrial abnormalities. However, functional studies of ANT1 mutations in mammalian cells are lacking, because they have been hindered by the fact that ANT1 expression leads to apoptotic cell death in commonly utilized replicating cell lines. Here, we successfully express functional ANT1 in differentiated mouse myotubes, which naturally contain high levels of ANT1, without causing cell death. We demonstrate, for the first time in these disease-relevant mammalian cells, that mutant human ANT1 causes dominant mitochondrial defects characterized by decreased ADP-ATP exchange function and abnormal translocator reversal potential. These abnormalities are not due to ANT1 loss of function, because knocking down Ant1 in myotubes causes functional changes different from ANT1 mutants. Under certain physiological conditions, mitochondria consume ATP to maintain membrane potential by reversing the ADP-ATP transport. The modified properties of mutant ANT1 can be responsible for disease pathogenesis in adPEO, because exchange reversal occurring at higher than normal membrane potential can cause excessive energy depletion and nucleotide imbalance in ANT1 mutant muscle cells.

  14. adPEO mutations in ANT1 impair ADP–ATP translocation in muscle mitochondria

    Science.gov (United States)

    Kawamata, Hibiki; Tiranti, Valeria; Magrané, Jordi; Chinopoulos, Christos; Manfredi, Giovanni

    2011-01-01

    Mutations in the heart and muscle isoform of adenine nucleotide translocator 1 (ANT1) are associated with autosomal-dominant progressive external opthalmoplegia (adPEO) clinically characterized by exercise intolerance, ptosis and muscle weakness. The pathogenic mechanisms underlying the mitochondrial myopathy caused by ANT1 mutations remain largely unknown. In yeast, expression of ANT1 carrying mutations corresponding to the human adPEO ones causes a wide range of mitochondrial abnormalities. However, functional studies of ANT1 mutations in mammalian cells are lacking, because they have been hindered by the fact that ANT1 expression leads to apoptotic cell death in commonly utilized replicating cell lines. Here, we successfully express functional ANT1 in differentiated mouse myotubes, which naturally contain high levels of ANT1, without causing cell death. We demonstrate, for the first time in these disease-relevant mammalian cells, that mutant human ANT1 causes dominant mitochondrial defects characterized by decreased ADP–ATP exchange function and abnormal translocator reversal potential. These abnormalities are not due to ANT1 loss of function, because knocking down Ant1 in myotubes causes functional changes different from ANT1 mutants. Under certain physiological conditions, mitochondria consume ATP to maintain membrane potential by reversing the ADP–ATP transport. The modified properties of mutant ANT1 can be responsible for disease pathogenesis in adPEO, because exchange reversal occurring at higher than normal membrane potential can cause excessive energy depletion and nucleotide imbalance in ANT1 mutant muscle cells. PMID:21586654

  15. Acute visual loss with ophthalmoplegia after spinal surgery: report of a case and review of the literature.

    Science.gov (United States)

    Mukherjee, Bipasha; Alam, Mohammad Shahid

    2014-09-01

    We report a case of a 15-year-old boy who presented with profound visual loss and complete ophthalmoplegia after an uneventful spinal surgery for removal of cervical osteoblastoma. Postoperative visual loss following nonocular surgery is, fortunately rare, yet a devastating complication. The most common cause is ischemic optic neuropathy, but it can also be due to central retinal occlusion or cortical blindness. Visual loss in conjunction with ophthalmoplegia is rarely seen, and there are very few reports in the literature. We also review the related literature and highlight the mechanism and preventive measures.

  16. Acute visual loss with ophthalmoplegia after spinal surgery: Report of a case and review of the literature

    Directory of Open Access Journals (Sweden)

    Bipasha Mukherjee

    2014-01-01

    Full Text Available We report a case of a 15-year-old boy who presented with profound visual loss and complete ophthalmoplegia after an uneventful spinal surgery for removal of cervical osteoblastoma. Postoperative visual loss following nonocular surgery is, fortunately rare, yet a devastating complication. The most common cause is ischemic optic neuropathy, but it can also be due to central retinal occlusion or cortical blindness. Visual loss in conjunction with ophthalmoplegia is rarely seen, and there are very few reports in the literature. We also review the related literature and highlight the mechanism and preventive measures.

  17. Boundary Lubrication of PEO-PPO-PEO Triblock Copolymer Physisorbed on Polypropylene, Polyethylene, and Cellulose Surfaces

    KAUST Repository

    Li, Yangyang

    2012-02-22

    In situ lateral force microscopy (LFM) and X-ray photoelectron spectroscopy (XPS) were used to probe the lubrication behavior of an aqueous solution of poly(oxyethylene)-poly(oxypropylene)-poly(oxyethylene) (PEO-PPO-PEO) symmetric triblock copolymer on thin films of polypropylene (PP), polyethylene (PE), and cellulose. LFM experiments were carried out while the substrates were immersed in water and in solutions of the copolymer. The friction coefficient on PP and PE was reduced after adsorption from the PEO-PPO-PEO aqueous solution while the opposite effect was observed for cellulose surfaces. A critical normal loading force, at which the friction coefficient of the lubricated and unlubricated surfaces is equal, was identified and related to the affinity of the polymer with the substrate. Further experiments were performed to mimic practical operations involving lubricant addition during manufacturing and postprocessing removal. XPS was used to verify the presence of the lubricant on the polymeric substrates and to evaluate its removal by water washing. The lubricant layer was easily removed by water from the PP and cellulose surfaces while a durable layer was found on PE. The XPS results were in agreement with the highest critical normal loading force measured for PE (52 nN for PE in contrast to a minimum of 10 nN for cellulose). While several reports exist on lubrication on hard surfaces, friction behavior on soft surfaces is still not well documented as the substrates usually deform under loading pressure. Therefore, we also propose a simple lubrication model for PP, PE, and cellulose and the use of critical normal loading force as a parameter to predict lubricity and durability of adsorbed nonionic block copolymers. © 2012 American Chemical Society.

  18. Interaction of Curcumin with PEO-PPO-PEO block copolymers: a molecular dynamics study.

    Science.gov (United States)

    Samanta, Susruta; Roccatano, Danilo

    2013-03-21

    Curcumin, a naturally occurring drug molecule, has been extensively investigated for its various potential usages in medicine. Its water insolubility and high metabolism rate require the use of drug delivery systems to make it effective in the human body. Among various types of nanocarriers, block copolymer based ones are the most effective. These polymers are broadly used as drug-delivery systems, but the nature of this process is poorly understood. In this paper, we propose a molecular dynamics simulation study of the interaction of Curcumin with block copolymer based on polyethylene oxide (PEO) and polypropylene oxide (PPO). The study has been conducted considering the smallest PEO and PPO oligomers and multiple chains of the block copolymer Pluronic P85. Our study shows that the more hydrophobic 1,2-dimethoxypropane (DMP) molecules and PPO block preferentially coat the Curcumin molecule. In the case of the Pluronic P85, simulation shows formation of a drug-polymer aggregate within 50 ns. This process leaves exposed the PEO part of the polymers, resulting in better solvation and stability of the drug in water.

  19. Acid-Labile Amphiphilic PEO-b-PPO-b-PEO Copolymers: Degradable Poloxamer Analogs.

    Science.gov (United States)

    Worm, Matthias; Kang, Biao; Dingels, Carsten; Wurm, Frederik R; Frey, Holger

    2016-05-01

    Poly ((ethylene oxide)-b-(propylene oxide)-b-(ethylene oxide)) triblock copolymers commonly known as poloxamers or Pluronics constitute an important class of nonionic, biocompatible surfactants. Here, a method is reported to incorporate two acid-labile acetal moieties in the backbone of poloxamers to generate acid-cleavable nonionic surfactants. Poly(propylene oxide) is functionalized by means of an acetate-protected vinyl ether to introduce acetal units. Three cleavable PEO-PPO-PEO triblock copolymers (Mn,total = 6600, 8000, 9150 g·mol(-1) ; Mn,PEO = 2200, 3600, 4750 g·mol(-1) ) have been synthesized using anionic ring-opening polymerization. The amphiphilic copolymers exhibit narrow molecular weight distributions (Ð = 1.06-1.08). Surface tension measurements reveal surface-active behavior in aqueous solution comparable to established noncleavable poloxamers. Complete hydrolysis of the labile junctions after acidic treatment is verified by size exclusion chromatography. The block copolymers have been employed as surfactants in a miniemulsion polymerization to generate polystyrene (PS) nanoparticles with mean diameters of ≈200 nm and narrow size distribution, as determined by dynamic light scattering and scanning electron microscopy. Acid-triggered precipitation facilitates removal of surfactant fragments from the nanoparticles, which simplifies purification and enables nanoparticle precipitation "on demand."

  20. Nanostructure of PEO-polyurethane-PEO triblock copolymer micelles in water.

    Science.gov (United States)

    Caba, Beth L; Zhang, Qian; Carroll, Matthew R J; Woodward, Robert C; St Pierre, Timothy G; Gilbert, Elliot P; Riffle, Judy S; Davis, Richey M

    2010-04-01

    Novel hydrophilic triblock copolymers which form micelles in aqueous solution were studied by static and dynamic light scattering (SLS and DLS), small angle neutron scattering (SANS) and densitometry. The polymers were symmetric A-B-A block copolymers having two poly(ethylene oxide) (PEO) tail blocks and a polyurethane (PU) center segment that contained pendant carboxylic acids. The aggregation number of the micelles decreased with increasing PEO mass content. When attempting to fit the SANS data it was found that no single model was suitable over the entire range of block lengths and PEO mass concentrations investigated here. For the polymer with the highest aggregation number, the data were fitted with a triblock model consisting of a homogeneous core with a corona of non-interacting Gaussian chains for which only two free parameters were required: the radius of the core and the radius of gyration of the corona. In this case, the core was found to be effectively dry. At lower aggregation numbers, a star polymer model generated significantly better fits, suggesting the absence of any identifiable central core structure. Good agreement was found between the sizes measured by DLS, SANS and theoretical predictions of micelle size from a density distribution theory. These results show that when significant changes in aggregation number occur, the nanostructure of the micelle can change substantially even for polymers that are remarkably similar. Copyright 2009 Elsevier Inc. All rights reserved.

  1. Patient with pontine warning syndrome and bilateral posterior internuclear ophthalmoplegia: case report

    Directory of Open Access Journals (Sweden)

    Su Li

    2010-06-01

    Full Text Available Abstract Background Capsular warning syndrome was first described in 1993, featured with repetitive episodes of motor and/or sensory dysfunction without cortical signs. Recently, it has been demonstrated that clinically typical capsular warning syndrome can be associated with pontine infarct and the term “pontine warning syndrome� was coined. Case Presentation A 54-year-old woman with a history of hypertension was seen with profound left-sided hemiplegia. She had had 3 episodes of left-sided weakness before complete hemiplegia. Her speech was slurred. Left central facial palsy and hemiglossoplegia were presented. Her left plantar response was extensor and bilateral posterior internuclear ophthalmoplegia was seen on neurologic examination. Biochemical tests revealed hyperglycemia and dyslipidemia on the next day. MRI demonstrated an acute right paramedian pontine infarct. The patient was commenced on oral clopidogrel, atorvastatin and acarbose. After 23 days of hospitalization, she was discharged with severe left hemiplegia. Conclusions 1 Pontine warning syndrome may be underestimated and understudied. 2 Posterior internuclear ophthalmoplegia is a rare clinical sign in cerebrovascular diseases, while it can help to locate a brainstem lesion rather than an internal capsular one. 3 Blood pressure lowing administration may be improper for patients with pontine warning syndrome.

  2. Control of the PEO chain conformation on nanoparticles by adsorption of PEO-block-poly(L-lysine) copolymers and its significance on colloidal stability and protein repellency.

    Science.gov (United States)

    Louguet, Stéphanie; Kumar, Anitha C; Guidolin, Nicolas; Sigaud, Gilles; Duguet, Etienne; Lecommandoux, Sébastien; Schatz, Christophe

    2011-11-01

    The physical adsorption of PEO(n)-b-PLL(m) copolymers onto silica nanoparticles and the related properties of poly(ethylene oxide) (PEO)-coated particles were studied as a function of the block copolymer composition. Copolymers adopt an anchor-buoy conformation at the particle surface owing to a preferential affinity of poly(L-lysine) (PLL) blocks with the silica surface over PEO blocks when a large excess of copolymer is used. The interdistance between PEO chains at particle surface is highly dependent on the size of PLL segments; a dense brush of PEO is obtained for short PLL blocks (DP = 10), whereas PEO chains adopt a so-called interacting "mushroom" conformation for large PLL blocks (DP = 270). The size of the PEO blocks does not really influence the copolymer surface density, but it has a strong effect on the PEO layer thickness as expected. Salt and protein stability studies led to similar conclusions about the effectiveness of a PEO layer with a dense brush conformation to prevent colloidal aggregation and protein adsorption. Besides, a minimal PEO length is required to get full stabilization properties; as a matter of fact, both PEO(45)-b-PLL(10) and PEO(113)-b-PLL(10) give rise to a PEO brush conformation but only the latter copolymer efficiently stabilizes the particles in the presence of salt or proteins.

  3. Solid State Electrolytes Prepared from PEO (360) Silanated Silica

    Science.gov (United States)

    Maitra, P.; Ding, J.; Liu, B.; Wunder, S. L.; Lin, H.-P.; Chua, D.; Salomon, M.

    2002-01-01

    All solid state composite electrolytes were prepared using fumed silica (SiO2) silanated with an oligomeric polyethylene oxide (PEO) silane containing 6-9 ethylene oxide repeat units, a PEO matrix and LiClO4 (8/1 O/Li). The PEO-silane covalently attached to the silica was amorphous, with a T(sub g) that increased from -90 C to -53 C after attachment. The conductivity of films prepared using the PEO-silanated silica increased to approx. 6 x 10(exp -5) S/cm at RT compared with approx. 1 x 10(-5) S/cm for films prepared with unsilanated SiO2.

  4. Sequential and competitive adsorption of peptides at pendant PEO layers.

    Science.gov (United States)

    Wu, Xiangming; Ryder, Matthew P; McGuire, Joseph; Snider, Joshua L; Schilke, Karl F

    2015-06-01

    Earlier work provided direction for development of responsive drug delivery systems based on modulation of the structure, amphiphilicity, and surface density of bioactive peptides entrapped within pendant polyethylene oxide (PEO) brush layers. In this work, we describe the sequential and competitive adsorption behavior of such peptides at pendant PEO layers. Three cationic peptides were used for this purpose: the arginine-rich, amphiphilic peptide WLBU2, a peptide chemically identical to WLBU2 but of scrambled sequence (S-WLBU2), and the non-amphiphilic peptide poly-L-arginine (PLR). Optical waveguide lightmode spectroscopy (OWLS) was used to quantify the rate and extent of peptide adsorption and elution at surfaces coated with PEO. UV spectroscopy and time-of-flight secondary ion mass spectrometry (TOF-SIMS) were used to quantify the extent of peptide exchange during the course of sequential and competitive adsorption. Circular dichroism (CD) was used to evaluate conformational changes after adsorption of peptide mixtures at PEO-coated silica nanoparticles. Results indicated that amphiphilic peptides are able to displace adsorbed, non-amphiphilic peptides in PEO layers, while non-amphiphilic peptides were not able to displace more amphiphilic peptides. In addition, peptides of greater amphiphilicity dominated the adsorption at the PEO layer from mixtures with less amphiphilic or non-amphiphilic peptides.

  5. Definition of formulation design space, in vitro bioactivity and in vivo biodistribution for hydrophilic drug loaded PLGA/PEO-PPO-PEO nanoparticles using OFAT experiments.

    Science.gov (United States)

    Simonoska Crcarevska, M; Geskovski, N; Calis, S; Dimchevska, S; Kuzmanovska, S; Petruševski, G; Kajdžanoska, M; Ugarkovic, S; Goracinova, K

    2013-04-11

    Modified nanoprecipitation method was used for improved incorporation of hydrophilic drug (irinotecan hydrochloride) into the PLGA/PEO-PPO-PEO blended and blended/adsorbed nanoparticles. One factor at a time (OFAT) variation experiments were conducted in order to determine key formulation factors (concentration and volume of drug solution, evaporation rate and PLGA/PEO-PPO-PEO ratio) influencing nanoparticle properties (particle size and size distribution, encapsulation efficiency, drug content, zeta potential, drug dissolution rate, as well as protein binding capacity). The insight into in vivo behavior of prepared nanoparticles and their potential for effective anticancer treatment was gained by performing biodistribution and cell culture studies as part of OFAT experiments. The mean particle size, mainly dependent upon PLGA/PEO-PPO-PEO ratio, was in the range of 112-125 nm, with narrow unimodal distribution (PDI∼0.1). Encapsulation efficiency (32-63%) was impacted by evaporation rate and PLGA/PEO-PPO-PEO ratio. Drug content (0.2-1.51%) and controlled release properties were related to the influence of all tested formulation factors. Structural information for the studied nanoparticles was obtained using DSC and FT-IR spectroscopy. Zeta potential values indicated that presence of PEO-PPO-PEO in the formulations shielded the high surface negative charge of PLGA. PEO-PPO-PEO surface coverage of PLGA/PEO-PPO-PEO blended as well as blended/adsorbed nanoparticles depended upon amount of used PEO-PPO-PEO during preparation procedure and was related to the protein resistant characteristics of nanoparticles. Results from in vivo studies evidenced prolonged blood circulation time of the prepared nanoparticles, while cell culture studies indicated higher in vitro bioefficacy compared to free drug. Performed experiments defined possible design space and justified further optimization of formulation using experimental design studies.

  6. Langmuir monolayers of non-ionic polymers: Equilibrium of metastability? Case study of PEO and its PPO-PEO diblock copolymers

    NARCIS (Netherlands)

    Deschenes, L.; Saint-Germain, F.; Lyklema, J.

    2015-01-01

    Stability and reorganization in Langmuir films of PEO in PEO homopolymers and PPO–PEO block copolymers were investigated using film balance measurements. The apparent fractional losses of EO segments transferred into the subphase resulting from successive compression–expansion cycles have been estim

  7. Wall-eyed bilateral internuclear ophthalmoplegia (webino syndrome and myelopathy in pyoderma gangrenosum

    Directory of Open Access Journals (Sweden)

    Marco Aurélio Lana

    1990-12-01

    Full Text Available A 35-year-old female with pyoderma gangrenosum developed paraparesis with a sensory level at L1. Three months later she complained of diplopia and was found to have bilateral internuclear ophthalmoplegia with exotropia and no ocular convergence. The term Webino syndrome has been coined to design this set of neuro-opthalmologic findings. Although it was initially attributed to lesions affecting the medial longitudinal fasciculus and the medial rectus subnuclei of the oculomotor complex in the midbrain the exact location of the lesion is still disputed. In the present case both myelopathy and Webino syndrome were probably due to vascular occlusive disease resulting from central nervous system vasculitis occurring in concomitance to pyoderma gangrenosum.

  8. Ataxia, ophthalmoplegia, and impairment of consciousness in a 19-month-old American boy.

    Science.gov (United States)

    Gliebus, Gediminas; Faerber, Eric N; Valencia, Ignacio; Khurana, Divya S; Singh, Sabina B; Legido, Agustín

    2014-06-01

    A 19-month-old, white, Pennsylvanian boy, with an unremarkable medical history, presented to our hospital with a 3-week history of nonbloody, nonbilious emesis up to 5 times a day and nonbloody diarrhea. Ten days before admission, his gait became progressively unsteady, until he finally refused to walk. A day before admission, he found it difficult to move his eyes. The patient was hypoactive. History, physical and neurologic examination, blood and cerebrospinal (CSF) fluid studies, and neuroimaging studies ruled out the most frequent causes of acute ataxia. The etiology of bilateral, complete ophthalmoplegia was also taken into consideration. Magnetic resonance imaging (MRI) findings of bilateral thalami and mammillary bodies provided diagnostic clues. Additional history and specific tests established the final diagnosis and treatment plan. The patient improved to a normal neurologic state. This case provides important practical information about an unusual malnutrition cause of acute ataxia, particularly in young children of developing countries.

  9. How PEO-PPO-PEO triblock polymer micelles control the synthesis of gold nanoparticles: temperature and hydrophobic effects.

    Science.gov (United States)

    Khullar, Poonam; Mahal, Aabroo; Singh, Vijender; Banipal, Tarlok Singh; Kaur, Gurinder; Bakshi, Mandeep Singh

    2010-07-06

    Aqueous micellar solutions of F68 (PEO(78)-PPO(30)-PEO(78)) and P103 (PEO(17)-PPO(60)-PEO(17)) triblock polymers were used to synthesize gold (Au) nanoparticles (NPs) at different temperatures. All reactions were monitored with respect to reaction time and temperature by using UV-visible studies to understand the growth kinetics of NPs and the influence of different micellar states on the synthesis of NPs. The shape, size, and locations of NPs in the micellar assemblies were determined with the help of TEM, SEM, and EDS analyses. The results explained that all reactions were carried out with the PEO-PPO-PEO micellar surface cavities present at the micelle-solution interface and were precisely controlled by the micellar assemblies. Marked differences were detected when predominantly hydrophilic F68 and hydrophobic P103 micelles were employed to conduct the reactions. The UV-visible results demonstrated that the reduction of gold ions into nucleating centers was channeled through the ligand-metal charge-transfer complex (LMCT) and carried out by the surface cavities. Excessive hydration of the surface cavities in the case of F68 micelles produced a few small NPs, but their yield and size increased as the micelles were dehydrated under the effect of increasing temperature. The results concluded that the presence of well-defined predominantly hydrophobic micelles with a compact micelle-solution interfacial arrangement of surface cavities ultimately controlled the reaction.

  10. Effect of interfaces on the melting of PEO confined in triblock PS-b-PEO-b-PS copolymers.

    Science.gov (United States)

    Beaudoin, E; Phan, T N T; Robinet, M; Denoyel, R; Davidson, P; Bertin, D; Bouchet, R

    2013-08-27

    Block copolymers form nanostructures that have interesting physical properties because they combine, for a single compound, the complementary features brought by each block. However, in order to fully exploit these properties, the physical state of each kind of domain must be precisely controlled. In this work, triblock PS-b-PEO-b-PS copolymers consisting of a central poly(ethylene oxide) (PEO) block covalently bonded to polystyrene (PS) blocks were synthesized by Atom Transfer Radical Polymerization. Their morphology was investigated by X-ray scattering and TEM experiments whereas their thermodynamic behavior was characterized by DSC. A strong decrease of both the melting temperature and the degree of crystallinity of PEO, due to its confinement between the PS domains, was observed and analyzed with a modified Gibbs-Thomson equation, following the approaches used for fluids confined in porous media. The existence of an amorphous bound layer, a few nanometers thick, at the PEO/PS interface, that does not undergo any phase transition in the temperature range investigated, accounts for both the melting temperature depression and the decrease of crystallinity upon confinement. This interfacial layer may significantly affect the mechanical and transport properties of these block copolymers that find applications as solid polymer electrolytes in batteries for example. Moreover, the value obtained for the solid PEO/liquid PEO surface tension is lower than those previously published but is thermodynamically consistent with the surface tensions of polymers at the solid/vapor and liquid/vapor interfaces.

  11. PEO-LiClO4-ZSM5 composite polymer electrolyte (IV): Polarized optical microscopy study

    Institute of Scientific and Technical Information of China (English)

    XI Jingyu; QIU Xinping; ZHU Wentao; CHEN Liquan

    2005-01-01

    Polarized optical microscopy (POM) results show that ZSM5 has great influence on both the nucleation stage and the growth stage of PEO spherulites. Part of ZSM5 particles can act as the nucleus of PEO spherulites and thus increase the amount of PEO spherulites. On the other hand, ZSM5 can restrain the recrystallization tendency of PEO chains through Lewis acid-base interaction and hence decrease the growth speed of PEO spherulites. The increasing amount of PEO spherulites, decreasing size of PEO spherulites, and the incomplete crystallization are all beneficial for creating more continuous amorphous phases of PEO, which is very important for the transporting of Li+ ions. An adequate amount of ZSM5 can enhance the room temperature ionic conductivity of PEO-LiClO4 based polymer electrolyte for more than two magnitudes.

  12. Magnetic nanoparticles (MNPs) covalently coated by PEO-PPO-PEO block copolymer for drug delivery.

    Science.gov (United States)

    Wang, Ning; Guan, Yueping; Yang, Liangrong; Jia, Lianwei; Wei, Xuetuan; Liu, Huizhou; Guo, Chen

    2013-04-01

    A stable drug carrier has been prepared by covalently coating magnetic nanoparticles (MNPs) with PEO-PPO-PEO block copolymer Pluronic P85. The particles were characterized by TEM, XRD, DLS, VSM, FTIR, and TGA. A typical product has a 15 nm magnetite core and a 100 nm hydrodynamic diameter with a narrow size distribution and is superparamagnetic with large saturation magnetization (57.102 emu/g) at room temperature. The covalently-coated Pluronic-MNPs (MagPluronics) were proven to be stable in different conditions, such as aqueous solution, 0.2 M PBS solution, and pH 13.5 solution, which would be significant for biological applications. Furthermore, MagPluronics also possess temperature-responsive property acquired from the Pluronic copolymer layer on their surface, which can cause conformational change of Pluronics and improve load and delivery efficiency of the particles. The temperature-controlled loading and releasing of hydrophobic model drug curcumin were tested with these particles. A loading efficiency of 81.3% and a sustained release of more than 4 days were achieved in simulated human body condition. It indicates that the covalently-coated MagPluronics are stable carriers with good drug-loading capacity and controlled-release property.

  13. Quantifying nisin adsorption behavior at pendant PEO layers.

    Science.gov (United States)

    Dill, Justen K; Auxier, Julie A; Schilke, Karl F; McGuire, Joseph

    2013-04-01

    The antimicrobial peptide nisin shows potent activity against Gram-positive bacteria including the most prevalent implant-associated pathogens. Its mechanism of action minimizes the opportunity for the rise of resistant bacteria and it does not appear to be toxic to humans, suggesting good potential for its use in antibacterial coatings for selected medical devices. A more quantitative understanding of nisin loading and release from polyethylene oxide (PEO) brush layers will inform new strategies for drug storage and delivery, and in this work optical waveguide lightmode spectroscopy was used to record changes in adsorbed mass during cyclic adsorption-elution experiments with nisin, at uncoated and PEO-coated surfaces. PEO layers were prepared by radiolytic grafting of Pluronic® surfactant F108 or F68 to silanized silica surfaces, producing long- or short-chain PEO layers, respectively. Kinetic patterns were interpreted with reference to a model accounting for history-dependent adsorption, in order to evaluate rate constants for nisin adsorption and desorption, as well as the effect of pendant PEO on the lateral clustering behavior of nisin. Nisin adsorption was observed at the uncoated and F108-coated surfaces, but not at the F68-coated surfaces. Nisin showed greater resistance to elution by peptide-free buffer at the uncoated surface, and lateral rearrangement and clustering of adsorbed nisin was apparent only at the uncoated surface. We conclude peptide entrapment at the F108-coated surface is governed by a hydrophobic inner region of the PEO brush layer that is not sufficient for nisin entrapment in the case of the shorter PEO chains of the F68-coated surface.

  14. Hydrogel formation by the 'topological conversion' of cyclic PLA-PEO block copolymers

    OpenAIRE

    Yamamoto, Takuya; Inoue, Kotaro; Tezuka, Yasuyuki

    2016-01-01

    An amphiphilic cyclic block copolymer consisting of poly(L- or D-lactide) and poly(ethylene oxide), that is, PLLA-PEO or PDLA-PEO, was synthesized from its corresponding linear triblock precursor, PLLA-PEO-PLLA or PDLA-PEO-PDLA, respectively, with alkenyl end groups. A mixture of the micellar dispersions of linear PLLA-PEO-PLLA and linear PDLA-PEO-PDLA formed a gel upon heating, whereas a mixture of the cyclic counterparts did not undergo this phase transition. These results suggest that the ...

  15. Plasma process control for improved PEO coatings on magnesium alloys

    Science.gov (United States)

    Hussein, Riyad Omran

    Plasma Electrolytic Oxidation (PEO) is a high voltage plasma-assisted oxidation process uses an environmentally-friendly aqueous electrolyte to oxidize the metal surfaces to form ceramic oxide coatings which impart a high corrosion and wear resistance. One of the main advantages of PEO process is that it can be applied to treat samples with complex shapes, and surfaces with different composition and microstructure. The PEO process of Mg alloys is strongly influenced by such parameters as electrolyte composition and concentration, current or voltage applied and substrate alloy. Generally, these parameters have a direct influence on the discharging behavior. The discharges play an essential role in the formation and resulting composition of the 3-layer oxide structure. A detailed knowledge of the coating mechanisms is extremely important in order to produce a desired coating quality to reach the best performance of the PEO coatings in terms of corrosion resistance and tribological properties (wear rate, COF). During PEO processing of magnesium, some of the metal cations are transferred outwards from the substrate and react with anions to form ceramic coatings. Also, due to the high electric field in the discharge channels, oxygen anions transfer towards the magnesium substrate and react with Mg2+ cations to form a ceramic coating. Although, in general, PEO coating of Mg alloys produces the three-layered structure, the relative proportions of the three-layers are strongly influenced by the PEO processing parameters. In PEO process, the ceramic coating grows inwards to the alloy substrate and outwards to the coating surface simultaneously. For the coating growth, there are three simultaneous processes taking place, namely the electrochemical, the plasma chemical reactions and thermal diffusion. Optical emission spectroscopy (OES) was employed for the discharge characterization by following the substrate and electrolyte element present in the plasma discharge during the

  16. Adsorption and association of a symmetric PEO-PPO-PEO triblock copolymer on polypropylene, polyethylene, and cellulose surfaces.

    Science.gov (United States)

    Li, Yan; Liu, Hongyi; Song, Junlong; Rojas, Orlando J; Hinestroza, Juan P

    2011-07-01

    The association of a symmetric polyoxyethylene-polyoxypropylene-polyoxyethylene (PEO(19)-PPO(29)-PEO(19)) triblock copolymer adsorbed from aqueous solutions onto polypropylene (PP), polyethylene (PE), and cellulose surfaces was probed using Atomic Force Microscopy (AFM). Significant morphological differences between the polyolefin substrates (PP and PE) and the cellulose surfaces were observed after immersion of the films in the PEO(19)-PPO(29)-PEO(19) solutions. When the samples were scanned, while immersed in solutions of the triblock copolymer, it was revealed that the structures adsorbed on the polyolefin surfaces were smoothed by the adsorbed PEO(19)-PPO(29)-PEO(19). In contrast, those structures on the hydrophilic cellulose surfaces were sharpened. These observations were related to the roughness of the substrate and the energy of interaction between the surfaces and the PEO and PPO polymer segments. The interaction energy between each of the blocks and the surface was calculated using molecular dynamics simulations. It is speculated that the associative structures amply reported in aqueous solution at concentrations above the critical micelle concentration, CMC, are not necessarily preserved upon adsorption; instead, it appears that molecular arrangements of the anchor-buoy type and hemimicelles prevail. The reported data suggests that the roughness of the surface, as well as its degree of hydrophobicity, have a large influence on the nature of the resulting adsorbed layer. The reported observations are valuable in explaining the behavior of finishing additives and lubricants commonly used in textile and fiber processing, as well as the effect of the morphology of the boundary layers on friction and wear, especially in the case of symmetric triblock copolymers, which are commonly used as antifriction, antiwear additives.

  17. Concentration effects on peptide elution from pendant PEO layers.

    Science.gov (United States)

    Wu, Xiangming; Ryder, Matthew P; McGuire, Joseph; Schilke, Karl F

    2014-06-01

    In earlier work, we have provided direction for development of responsive drug delivery systems based on modulation of structure and amphiphilicity of bioactive peptides entrapped within pendant polyethylene oxide (PEO) brush layers. Amphiphilicity promotes retention of the peptides within the hydrophobic inner region of the PEO brush layer. In this work, we describe the effects of peptide surface density on the conformational changes caused by peptide-peptide interactions, and show that this phenomenon substantially affects the rate and extent of peptide elution from PEO brush layers. Three cationic peptides were used in this study: the arginine-rich amphiphilic peptide WLBU2, the chemically identical but scrambled peptide S-WLBU2, and the non-amphiphilic homopolymer poly-l-arginine (PLR). Circular dichroism (CD) was used to evaluate surface density effects on the structure of these peptides at uncoated (hydrophobic) and PEO-coated silica nanoparticles. UV spectroscopy and a quartz crystal microbalance with dissipation monitoring (QCM-D) were used to quantify changes in the extent of peptide elution caused by those conformational changes. For amphiphilic peptides at sufficiently high surface density, peptide-peptide interactions result in conformational changes which compromise their resistance to elution. In contrast, elution of a non-amphiphilic peptide is substantially independent of its surface density, presumably due to the absence of peptide-peptide interactions. The results presented here provide a strategy to control the rate and extent of release of bioactive peptides from PEO layers, based on modulation of their amphiphilicity and surface density.

  18. Correlating crystallization and ionic conductivity of PEO/graphene oxide nanocomposite

    Science.gov (United States)

    Cheng, Shan; Smith, Derrick; Hsuan, Grace; Li, Christopher

    2012-02-01

    Polyethylene oxide (PEO) is one of the best candidates for solid state electrolyte due to its chemical stability and strong ability to form complex with lithium salts. Crystallization behavior of PEO directly affects the lithium ion transport, and in turn the ionic conductivity of the electrolyte. By adding two dimensional graphene oxide nanosheets into PEO matrix, mechanical property of the latter is significantly strengthened, while the crystallization behavior of PEO is also altered by the graphene oxide sheets. The crystallization of PEO/graphene oxide nanocomposites was studied by differential scanning calorimetry (DSC) and the orientations of graphene oxide and PEO crystal were studied by small angle X-ray scattering and wide angle X-ray diffraction. PEO/graphene oxide nanocomposite doped with lithium salt was further fabricated and characterized by electrochemical impedance spectroscopy. Anisotropic ionic conductivity was observed for the nanocomposite electrolyte due to the orientation of graphene oxide and directional growth of PEO crystals.

  19. Thermodynamic properties of aqueous PEO-PPO-PEO micelles with added methylparaben determined by differential scanning calorimetry.

    Science.gov (United States)

    Thompson, Andre Lamont; Love, Brian James

    2013-05-15

    DSC experiments were performed on aqueous solutions of PEO-PPO-PEO (P105) amphiphiles in the low concentration regime (0-1%) to resolve the critical micelle concentration (cmc) both neat and co-formulated with methylparaben (MP). Further work was done at 10% amphiphilic copolymer concentrations and co-formulated with MP to resolve the variations in enthalpy. The compensation temperature, T(compensation), was determined from the analyses for neat P105 as 293.9 K; adding MP raises this to 328.43 K.

  20. Tolosa-Hunt syndrome: MR imaging features in 15 patients with 20 episodes of painful ophthalmoplegia

    Energy Technology Data Exchange (ETDEWEB)

    Schuknecht, B. [MRI Medical Radiological Institute Zurich (Switzerland)], E-mail: image-solution@ggaweb.ch; Sturm, V. [Department of Ophthalmology, University Hospital Zurich (Switzerland); Huisman, T.A.G.M. [MRI Medical Radiological Institute Zurich (Switzerland); Department of Radiology and Radiological Sciences, Johns Hopkins Hospital, Baltimore (United States); Landau, K. [Department of Ophthalmology, University Hospital Zurich (Switzerland)

    2009-03-15

    Purpose: (a) To assess MR features in patients with Tolosa-Hunt syndrome (THS) and to (b) correlate MR findings with criteria derived from previously reported pathologic observations. Methods: Fifteen patients with twenty episodes of painful ophthalmoplegia prospectively selected according to International Headache Society (IHS) standards underwent MR examinations focused on the cavernous sinus. Initial examinations in 20 and follow-up MR images in 17 episodes were retrospectively reviewed by 3 independent observers. Results: The primary criteria: an enhancing soft tissue lesion within the cavernous sinus, increase in size and lateral bulging of the anterior cavernous sinus contour were consistently present in 15 initial episodes and in 5 recurrences (20/20). Agreement among observers was 100%. The secondary criteria: internal carotid artery narrowing in 7 patients, extension towards the superior orbital fissure in 13 and orbital apex involvement in 8 patients were unanimously agreed upon in 87.5%, 86.6% and 80%. Complete resolution of findings was observed on follow-up studies. Conclusion: In patients with THS the MR features conform to previously reported pathologic findings. MR features are evocative of THS when an increase in size and bulging of the dural contour of the anterior CS supplemented by carotid artery involvement and extension towards the orbit are present. Resolution of findings within 6 months is required to support the diagnosis.

  1. Bilateral Internuclear Ophthalmoplegia in a Patient with Devic’s Neuromyelitis Optica

    Directory of Open Access Journals (Sweden)

    E. Garcia-Martin

    2010-11-01

    Full Text Available An unusual presentation of Devic’s neuromyelitis optica (NMO disease associated with bilateral internuclear ophthalmoplegia (INO is described. A 32-year-old pregnant patient was diagnosed with NMO. First symptoms were headache and sudden visual loss in her right eye (RE. Eighteen months ago, she reported other neurologic symptoms such as paresthesia. Based on her visual field, fundoscopy and Ishihara test, she was diagnosed with retrobulbar neuritis of the RE. After delivery, new neurologic symptoms resembling transverse myelitis appeared. She was treated with methylprednisolone and plasmapheresis, which improved her visual acuity; however, a sudden bilateral INO appeared, with adduction defect and nystagmus with abduction in both eyes. No improvement was obtained after treatment with azathioprine and rituximab. Paresis of the legs and the right arm persisted, but double vision and OIN gradually disappeared. At the end, the patient had a residual exophoria in the RE and nystagmus with abduction in the left eye. Prevalence of NMO is lower than one case per one million inhabitants, and it is not likely to affect the encephalic trunk; furthermore, bilateral INO in NMO is rare. Two major criteria and at least two of the three minor ones are required to confirm a NMO diagnosis, and our patient fulfilled these diagnosis criteria.

  2. Electrochemical Properties of Poly(ethylene oxide)(PEO) Doped TiO2-PEO Films Prepared by Sol-gel Dip Coating Technique

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    PEO modified TiO2-PEO organic-inorganic hybrid thin films were prepared via sol-gel dipping process on glass substrate pre-coated with ITO. The preparation parameters were studied. Electrochemical and optical properties of the films were characterized by cyclic voltammetric response and visible transmittance. X-ray diffraction (XRD) was used to determined the crystalline structure of the gel. The results show the sols added with PEO have acceptable stable periods for practical use. The PEO modified optical transitivity of the hybrid films has heavy effects on the crystallization of TiO2 during structural evolution because of the interaction between PEO and TiO2. PEO- TiO2 films have better electrochemical activity than the TiO2 equivalent behaved as higher Li+ insertion/extraction current density and cyclic reversibility.

  3. Formative Assessment Probes: Using the P-E-O Technique

    Science.gov (United States)

    Keeley, Page

    2013-01-01

    This article describes how observing whether objects sink or float in water using the P-E-O (Predict, Explain, and Observe) technique is an elementary precursor to developing explanations in later grades that involve an understanding of density and buoyancy. Beginning as early as preschool, elementary students engage in activities that encourage…

  4. PEO nanocomposite polymer electrolyte for solid state symmetric capacitors

    Indian Academy of Sciences (India)

    Nirbhay K Singh; Mohan L Verma; Manickam Minakshi

    2015-10-01

    Physical and electrochemical properties of polyethylene oxide (PEO)-based nanocomposite solid polymer electrolytes (NPEs) were investigated for symmetric capacitor applications. Nanosize fillers, i.e., Al2O3 and SiO2 incorporated polymer electrolyte exhibited higher ionic conductivity than those with filler-free composites. The composites have been synthesized by the completely dry (solution-free) hot-press method. The addition of filler in fractional amount to the solid polymer matrix at room temperature further enhances the ionic conductivity. Nature of the NPEs were studied using X-ray diffraction and energy-dispersive spectra analyses. Thermal stability of the resulting electrolyte was analysed by thermogravimetric analysis and differential scanning calorimetric studies. Morphology changes occurred during the addition of fillers was evidenced by scanning electronic microscope images. Solid polymer electrolytes exhibiting these parameters was found to be suitable for solid state capacitors. The results obtained from the electrolytes with an optimum compositions (PEO70AgI30)93 (Al2O3)7 and (PEO70AgI30)95 (SiO2)5 used in the (PEO70AgI30)70 (AC)30 electrodes for symmetric capacitor applications and their performances were analysed by impedance spectroscopic, Bode plot, cyclic voltammetry, discharge characteristics and leakage current profile.

  5. A novel mitochondrial tRNAAla gene variant causes chronic progressive external ophthalmoplegia in a patient with Huntington disease

    Directory of Open Access Journals (Sweden)

    Massimiliano Filosto

    2016-03-01

    Mitochondrial involvement is an emerging key determinant in the pathogenesis of Huntington disease and it is well known that mutant huntingtin influences the mitochondrial respiratory complexes II and III. A synergist effect of the HTT and MTTA mutations on respiratory chain function may be hypothesized in our patient and should be regarded as a spur for further studies on the mtDNA/HTT reciprocal interactions.

  6. Biodegradable polymer for sealing porous PEO layer on pure magnesium: An in vitro degradation study

    Science.gov (United States)

    Alabbasi, Alyaa; Mehjabeen, Afrin; Kannan, M. Bobby; Ye, Qingsong; Blawert, Carsten

    2014-05-01

    An attempt was made to seal the porous silicate-based plasma electrolytic oxidation (PEO) layer on pure magnesium (Mg) with a biodegradable polymer, poly(L-lactide) (PLLA), to delay the localized degradation of magnesium-based implants in body fluid for better in-service mechanical integrity. Firstly, a silicate-based PEO coating on pure magnesium was performed using a pulsed constant current method. In order to seal the pores in the PEO layer, PLLA was coated using a two-step spin coating method. The performance of the PEO-PLLA Mg was evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The EIS results showed that the polarization resistance (Rp) of the PEO-PLLA Mg was close to two orders of magnitude higher than that of the PEO Mg. While the corrosion current density (icorr) of the pure Mg was reduced by 65% with the PEO coating, the PEO-PLLA coating reduced the icorr by almost 100%. As expected, the Rp of the PEO-PLLA Mg decreased with increase in exposure time. However, it was noted that the Rp of the PEO-PLLA Mg even after 100 h was six times higher than that of the PEO Mg after 48 h exposure, and did not show any visible localized attack.

  7. End Group Effects on the Hydrogel Formation of PEO-PPO-PEO Triblock Copolymers

    Science.gov (United States)

    Cohen, Aaron; Ryu, Chang Y.; Jung, Gyoo Y.; Hwang, Hee Sung

    2012-02-01

    Pluronic F108, a triblock copolymer consisting of outer polyethylene oxide (PEO) chains and an inner polypropylene oxide (PPO) chains, has been shown to be an effective hydrogel matrix for DNA separation by capillary electrophoresis using single-stranded conformation polymorphism. This presentation will discuss a new pathway to potentially enhance the separation abilities of F108 by altering the chain end groups of the block copolymers. F108 is believed to form a micelle in aqueous solutions with the hydrophobic group in the interior, thus we expect considerable interaction between the DNA sample and the end groups found at the hydrophilic brush layers of the micelle. The rheological properties of end group derivatives of F108, in combination of small angle x-ray scattering, can reveal structural differences in the micelles. In particular, gelation temperature of the end group derivatives can be linked to differences in the micelle structure. Dynamic light scattering can also be used to determine the effects of chain end groups on the hydrodynamic size of the block copolymer micelles in dilute solution.

  8. Temperature-dependent raman spectroscopy of lithium triflate-PEO complexes: phase equilibrium and component interactions.

    Science.gov (United States)

    Alloin, Fannie; Hirankumar, Gurusamy; Pagnier, Thierry

    2009-12-31

    Poly(ethylene oxide) and complexes of lithium trifluorosulfonate-poly(ethylene oxide) (LiTf-PEO) with 4 PEO)(3)LiTf defined compound has been deduced from the experimental data. Subtraction of the Raman spectrum due to (PEO)(3)LiTf in each sample allowed us to determine for the first time the composition and the Li(+)-Tf(-) and Li(+)-PEO interactions in the part of the polymer not crystallized as (PEO)(3)LiTf. It is shown that the local interactions between cation and anion or between cation and PEO chain persist even in the melted state, up to near the liquidus temperature. In particular, the Li(+)-PEO interactions decrease significantly just below the liquidus temperature with a simultaneous strong increase in the ion pair concentration.

  9. Structural Properties of Bulk and Aqueous Systems of PEO-PIB-PEO Triblock Copolymers as Studied by Small-Angle Neutron Scattering and Cryo-Transmission Electron Microscopy

    DEFF Research Database (Denmark)

    Mortensen, Kell; Talmon, Yeshayahu; Gao, Bo

    1997-01-01

    The phase behavior of a low molecular weight (M-w = 6000) symmetric triblock copolymer of poly(ethylene oxide) and poly(isobutylene), PEO-PIB-PEO, in the bulk as well in aqueous, D2O, solutions has been studied using small-angle neutron scattering and cryo-transmission electron microscopy...

  10. Interaction between reduced glutathione and PEO-PPO-PEO copolymers in aqueous solutions: studied by 1H NMR and spin-lattice relaxation.

    Science.gov (United States)

    Jia, Lianwei; Guo, Chen; Yang, Liangrong; Xiang, Junfeng; Tang, Yalin; Liu, Huizhou

    2011-03-17

    In order to investigate the effect of PEO-PPO-PEO copolymers on the glutathione (GSH)/glutathione-S-transferase (GST) detoxification system, interaction between the copolymers and GSH is studied by NMR measurements. Selective rotating-frame nuclear Overhauser effect (ROE) experiment confirms that glutamyl (Glu) α-H of GSH has spatial contact with EO methylene protons. Spin-lattice relaxation times of GSH Glu α-H show a decrease when PEO-PPO-PEO copolymers are added, and the decrease is greater with copolymers possessing more EO units. Other protons of GSH show little change in the presence of the copolymers. The addition of GSH promotes the dehydration of PEO-PPO-PEO copolymers. This results from the breaking of hydrogen bonds between water and the polymers and the forming of hydrogen bonds between Glu α-carboxylate protons and oxygen atoms of EO units. The dissociation constant between GSH and P85 copolymer is determined by spin-lattice relaxation measurements, which shows the binding is of low affinity and the two molecules are in fast dissociation kinetics. This study suggests that GSH transporting or utilizing systems may be affected by treatment of PEO-PPO-PEO copolymers.

  11. Langmuir monolayers of non-ionic polymers: equilibrium or metastability? Case study of PEO and its PPO-PEO diblock copolymers.

    Science.gov (United States)

    Deschênes, Louise; Saint-Germain, François; Lyklema, Johannes

    2015-07-01

    Stability and reorganization in Langmuir films of PEO in PEO homopolymers and PPO-PEO block copolymers were investigated using film balance measurements. The apparent fractional losses of EO segments transferred into the subphase resulting from successive compression-expansion cycles have been estimated. The apparent loss is mainly Γ(max), M(n) and time-dependent. At surface concentrations Γ⩽0.32 mg/m(2), PEO films are in equilibrium. For 0.32⩽Γ⩽0.7 mg/m(2), the losses remain modest. Further compression leads to densification of the monolayer, requiring the interplay of thermodynamics and kinetic factors In the plateau regime, the loss is higher and constant for 1⩽Γ(max)⩽2 mg/m(2) upon maintaining the achieved surface area for 15 min. Similar losses were obtained for PEO homopolymers of high Mn and PPO353-PEO2295. It suggests that the PEO remains anchored in a metastable state at the air-water interface at surface concentration well above the onset of the plateau. Additional losses are incurred for PEO homopolymers for monolayers kept compressed in the plateau for 2 h. For the interpretation of these phenomena a combination of elements from self-consistent field theory and scaling is desirable with as a trend an increasing contribution of the latter with increasing surface concentration.

  12. Interaction of bovine serum albumin and human blood plasma with PEO-tethered surfaces : influence of PEO chain length, grafting density and temperature

    NARCIS (Netherlands)

    Norde, W.; Gage, R.A.

    2004-01-01

    Solid surfaces are modified by grafting poly(ethylene oxide), PEO, to influence their interaction with indwelling particles, in particular molecules of bovine serum albumin and human plasma proteins. As a rule, the grafted PEO layers suppress protein adsorption. The suppression is most effective whe

  13. Polyurethane modified with an antithrombin-heparin complex via polyethylene oxide linker/spacers: influence of PEO molecular weight and PEO-ATH bond on catalytic and direct anticoagulant functions.

    Science.gov (United States)

    Sask, Kyla N; Berry, Leslie R; Chan, Anthony K C; Brash, John L

    2012-10-01

    A segmented polyurethane (PU) was modified with polyethylene oxides (PEO) of varying molecular weight and end group. The PEO served as linker/spacers to immobilize an antithrombin-heparin (ATH) anticoagulant complex on the PU. Isocyanate groups were introduced into the PU to enable attachment of either "conventional" homo-bifunctional dihydroxy-PEO (PEO-OH surface) or a hetero-bifunctional amino-carboxy-PEO (PEO-COOH surface). The PEO surfaces were functionalized with N-hydroxysuccinimide (NHS) groups using appropriate chemistries, and ATH was attached to the distal NHS end of the PEO (PEO-OH-ATH and PEO-COOH-ATH surfaces). Water contact angle and fibrinogen adsorption measurements showed increased hydrophilicity and reduced fibrinogen adsorption from buffer on all PEO surfaces compared to unmodified PU. ATH uptake on NHS-functionalized PEO was quantified by radiolabeling. Despite the different PEO molecular weights and end groups, and NHS-functionalization chemistries, the surface densities of ATH were similar. The adsorption of fibrinogen and antithrombin (AT) from plasma was measured in a single experiment using dual radiolabeling. On PEO-ATH surfaces fibrinogen adsorption was minimal while AT adsorption was high showing the selectivity of the heparin moiety of ATH for AT. The PEO-COOH-ATH surfaces showed slightly greater AT adsorption than the PEO-OH-ATH surfaces. Thrombin adsorption on all of the PEO-ATH surfaces was greater than on the corresponding PEO surfaces without ATH, and was highest on the PEO-OH-ATH, suggesting potential anticoagulant properties for this surface via direct thrombin inhibition by the AT portion of ATH.

  14. Investigation of Drug Release from PEO Tablet Matrices in the Presence of Vitamin E as Antioxidant.

    Science.gov (United States)

    Shojaee, Saeed; Nokhodchi, Ali; Cumming, Iain; Alhalaweh, Amjad; Kaialy, Waseem

    2015-01-01

    The objective of this study was to investigate the influence of drug type on the release of drug from PEO matrix tablets accompanied with the impact of vitamin E succinate as antioxidant. The result showed that the presence of vitamin E promoted a stable release rate of soluble drug propranolol HCl from aged PEO matrix tablets, which was similar to fresh sample, regardless of molecular weight (MW) of PEO. However, the influence of the presence of vitamin E on the release rate of partially soluble drug, theophylline, was dependent on the MW of PEO; i.e., fast and unstable drug release was obtained in the case of low MW PEO 750 whereas stable drug release was obtained in the case of high MW PEO 303. The release of low water-soluble drug zonisamide was stable regardless of both the presence of vitamin E and the MW of PEO. The presence of vitamin E slightly slowed the release of zonisamide from aged PEO 303 matrices but not PEO 750 matrices. Therefore, in order to achieve a suitable controlled release profile from PEO matrices, not only the presence of vitamin E but also the solubility of the drug and the MW of polyox should be considered.

  15. Microporous polymer electrolyte based on PVDF-PEO

    Institute of Scientific and Technical Information of China (English)

    LI Jian; XI Jingyu; SONG Qing; TANG Xiaozhen

    2005-01-01

    @@ Since Wright et al.[1] found that the complex of PEO/alkali metals salt had the ability of ionic conductivity in 1973, in-depth studies have been carried out about various polymer electrolytes, which were applied to replacing the liquid electrolytes in lithium ion battery[2,3]. At present, polymer electrolytes mainly include three kinds: dry polymer electrolytes, gel polymer electrolytes and microporous polymer electrolytes.

  16. Ionic transport in P(VdF–HFP)–PEO based novel microporous polymer electrolytes

    Indian Academy of Sciences (India)

    M Deka; A Kumar

    2009-12-01

    A novel microporous polymer electrolyte (MPE) comprising blends of poly(vinylidene fluoride-cohexafluoropropylene) [P(VdF–HFP)] and polyethylene oxide (PEO) was prepared by phase inversion technique. It was observed that addition of PEO improved the pore configuration, such as pore size, pore connectivity and porosity of P(VdF–HFP) based membranes. The room temperature ionic conductivity was significantly enhanced. The highest porosity of about 65% and ionic conductivity of about 7 × 10-4 S cm-1 was obtained when the weight ratio of PEO was 40%. The liquid electrolyte uptake was found to increase with increase in porosity and pore size. However, at higher weight ratio of PEO (> 40%) porosity, pore size and ionic conductivity was decreased. This descending trend with further increase of PEO weight ratio was attributed to conglomeration effect of PEO at the pores.

  17. Phase transitions in polymer monolayers: Application of the Clapeyron equation to PEO in PPO-PEO Langmuir films.

    Science.gov (United States)

    Deschênes, Louise; Lyklema, Johannes; Danis, Claude; Saint-Germain, François

    2015-08-01

    In this paper we investigate the application of the two-dimensional Clapeyron law to polymer monolayers. This is a largely unexplored area of research. The main problems are (1) establishing if equilibrium is reached and (2) if so, identifying and defining phases as functions of the temperature. Once this is validated, the Clapeyron law allows us to obtain the entropy and enthalpy differences between two coexisting phases. In turn, this information can be used to obtain insight into the conformational properties of the films and changes therein. This approach has a wide potential for obtaining additional information on polymer adsorption at interfaces and the structure of their monolayer films. The 2D Clapeyron law was applied emphasizing polyethylene oxide (PEO) in polypropylene oxide (PPO)-PEO block copolymers, based on new well-defined data for their Langmuir films. Values for enthalpy per monomer of 0.12 and 0.23 kT were obtained for the phase transition of two different PEO chains (Neo of 2295 and 409, respectively). This enthalpy was estimated to correspond to 1.2±0.4 kT per EO monomer present in train conformation at the air/water interface.

  18. New synthesis of amphiphilic copolymers PE-g-PEO via esterfication

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A new series of high molecular weight amphiphilic graft copolymers PE-g-PEO has been prepared. The esterifications between PE-p-MS-g-MA and PEO with OH group at the chain end are carried out under different conditions. The compositions of these graft copolymers are studied by NMR and FTIR. It is found to be a convenient and efficient way to prepare high molecular weight PE-g-PEO graft copolymers.

  19. SYNTHESIS AND CHARACTERIZATION OF REACTIVE GRAFT COPOLYMER PDMS-g- (PEO-OH)

    Institute of Scientific and Technical Information of China (English)

    QIU Yongxing; YU Xiaojie; FENG Lingxian

    1995-01-01

    A new reactive graft copolymer, poly (dimethyl siloxane)-graft-ω-hydroxyl-poly (ethylene oxide) (PDMS-g-(PEO-OH)), was synthesized by the hydrosilylation reaction of α, ω-bifunctional PEO macromonomer (CH2=CH-CH2-PEO-OH) with poly (hydromethylsiloxane) (PHMS). The obtained copolymer, exhibited the expected comblike structure as indicated by the result of detailed characterization and the needed reactivity as demonstrated by the result of esterification between PDMS-g-(PEO-OH)and aminoacetic acid. This reactive graft copolymer is expected to be very useful in the preparation of new bioactive polymer materials.

  20. Formation and Properties of Vesicles from Cyclic Amphiphilic PS-PEO Block Copolymers.

    Science.gov (United States)

    Baba, Eisuke; Yatsunami, Toshiaki; Tezuka, Yasuyuki; Yamamoto, Takuya

    2016-10-11

    Linear polystyrene-poly(ethylene oxide)-polystyrene (PS-PEO-PS) block copolymers and corresponding cyclized PS-PEO counterparts with three different PS molecular weights were synthesized and self-assembled to investigate the effects arising from the topology. Linear PS5-PEO45-PS5 (L1) and cyclic PS10-PEO45 (C1) formed micelles. As previously reported for poly(n-butyl acrylate) and PEO block copolymers, the micelles from C1 showed more than 30 °C higher phase transition temperature (cloud point, Tc) than those from L1. Linear PS10-PEO45-PS10 (L2) and cyclic PS20-PEO45 (C2) resulted in the formation of a structure called large compound micelles. Self-assembly of linear PS40-PEO48-PS40 (L3) and cyclic PS86-PEO48 (C3) lead to the formation of vesicles. The vesicles were characterized by TEM, DLS, and SLS. Remarkably, the vesicles from L3 (Tc = 69, 59, and 48 °C in the presence of 1, 5, and 10 wt % of NaCl, respectively) were found to be somewhat more thermally stable than those from C3 (Tc = 62, 52, and 43 °C in the presence of 1, 5, and 10 wt % of NaCl, respectively). This trend of the thermal stability was counterintuitively opposed to the case of the micelles. Moreover, Tc of the vesicles was controlled by the ratio of L3 and C3.

  1. Improving Acquisition From Within: Suggestions From Our PEOs

    Science.gov (United States)

    2016-08-01

    Non­Developmental Items (NDI). This has tre­ mendous impacts across my portfolio , which is heavily reliant on COTS/NDI and could mitigate additional funding...clock” when the Defense budget is actually passed and not on Oct. 1, as they do now. Hiring Authority: The agility of a PEO to support its portfolio ...improved. I’ve re­ ceived very positive feedback on the learning value of these sessions and encouraged my subordinates to replicate the process at lower

  2. PEO Soldier Simulation Road Map VI - Command and Control Modeling

    Science.gov (United States)

    2009-11-01

    capa- bilities for the federation. In November of 2003, Brigadier General James Moran, PEO Soldier, commissioned the ORCEN to develop a model, or...Niki, Teague, Edward, Hen- derson, Dale, & Cook, James . 2008. Federated Simula- tions for Systems of Systems Integration. In: Proceed- ings of the...rocess for S oldier S ensors 8 m ons M on 6/16/08 Fri 1/23/09 93 M odel S oldier P ow er C onsum ption 8 m ons M on 6/16/08 Fri 1/23/09 94 B uild

  3. Preparation and evaluation of PEO-coated materials for a microchannel hemodialyzer.

    Science.gov (United States)

    Heintz, Keely; Schilke, Karl F; Snider, Joshua; Lee, Woo-Kul; Truong, Mitchell; Coblyn, Matthew; Jovanovic, Goran; McGuire, Joseph

    2014-07-01

    The marked increase in surface-to-volume ratio associated with microscale devices for hemodialysis leads to problems with hemocompatibility and blood flow distribution that are more challenging to manage than those encountered at the conventional scale. In this work stable surface modifications with pendant polyethylene oxide (PEO) chains were produced on polydimethylsiloxane (PDMS), polycarbonate microchannel, and polyacrylonitrile membrane materials used in construction of microchannel hemodialyzer test articles. PEO layers were prepared by radiolytic grafting of PEO-polybutadiene-PEO (PEO-PB-PEO) triblock polymers to the material surfaces. Protein repulsion was evaluated by measurement of surface-bound enzyme activity following contact of uncoated and PEO-coated surfaces with β-galactosidase. Protein adsorption was decreased on PEO-coated polycarbonate and PDMS materials to about 20% of the level recorded on the uncoated materials. Neither the triblocks nor the irradiation process was observed to have any effect on protein interaction with the polyacrylonitrile membrane, or its permeability to urea. This approach holds promise as a means for in situ application of safe, efficacious coatings to microfluidic devices for blood processing that will ensure good hemocompatibility and blood flow distribution, with no adverse effects on mass transfer.

  4. Molecular Dynamics Simulation Study of PEO-Based Nanocomposite Polymer Electrolytes el

    Science.gov (United States)

    Borodin, Oleg; Bandyopadhyaya, Rajdip; Smith, Grant D.

    2002-03-01

    Solid polymer electrolytes exhibit good chemical, electrochemical and photochemical stability in combination with good mechanical properties, ease of processing and adequate conductivity at elevated temperatures. Addition of solid nanoparticle fillers such as TiO2 and SiO2 to lithium solid polymer electrolytes is known to improve mechanical properties, interfacial stability, conductivity and transfer numbers, particularly for poly(ethylene oxide) (PEO) based polymer electrolytes. We have performed molecular dynamics simulations of PEO/LiBF4 and PEO/LiBF4/TiO2 systems in order to study changes of the structure and mechanism of ion conduction in PEO/LiBF4 near TiO2 surfaces compared to the bulk PEO/LiBF4.

  5. Adsorption of a PEO-PPO-PEO triblock copolymer on metal oxide surfaces with a view to reducing protein adsorption and further biofouling.

    Science.gov (United States)

    Yang, Y; Poleunis, C; Románszki, L; Telegdi, J; Dupont-Gillain, C C

    2013-01-01

    Abstract Biomolecule adsorption is the first stage of biofouling. The aim of this work was to reduce the adsorption of proteins on stainless steel (SS) and titanium surfaces by modifying them with a poly(ethylene oxide) (PEO)-poly(propylene oxide) (PPO)-PEO triblock copolymer. Anchoring of the central PPO block of the copolymer is known to be favoured by hydrophobic interaction with the substratum. Therefore, the surfaces of metal oxides were first modified by self-assembly of octadecylphosphonic acid. PEO-PPO-PEO preadsorbed on the hydrophobized surfaces of titanium or SS was shown to prevent the adsorption of bovine serum albumin (BSA), fibrinogen and cytochrome C, as monitored by quartz crystal microbalance (QCM). Moreover, X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry were used to characterize the surfaces of the SS and titanium after competitive adsorption of PEO-PPO-PEO and BSA. The results show that the adsorption of BSA is well prevented on hydrophobized surfaces, in contrast to the surfaces of native metal oxides.

  6. Hydrogen Bonding-Mediated Microphase Separation during the Formation of Mesoporous Novolac-Type Phenolic Resin Templated by the Triblock Copolymer, PEO-b-PPO-b-PEO

    Directory of Open Access Journals (Sweden)

    Wei-Cheng Chu

    2013-11-01

    Full Text Available After blending the triblock copolymer, poly(ethylene oxide-b-propylene oxide-b-ethylene oxide (PEO-b-PPO-b-PEO with novolac-type phenolic resin, Fourier transform infrared spectroscopy revealed that the ether groups of the PEO block were stronger hydrogen bond acceptors for the OH groups of phenolic resin than were the ether groups of the PPO block. Thermal curing with hexamethylenetetramine as the curing agent resulted in the triblock copolymer being incorporated into the phenolic resin, forming a nanostructure through a mechanism involving reaction-induced microphase separation. Mild pyrolysis conditions led to the removal of the PEO-b-PPO-b-PEO triblock copolymer and formation of mesoporous phenolic resin. This approach provided a variety of composition-dependent nanostructures, including disordered wormlike, body-centered-cubic spherical and disorder micelles. The regular mesoporous novolac-type phenolic resin was formed only at a phenolic content of 40–60 wt %, the result of an intriguing balance of hydrogen bonding interactions among the phenolic resin and the PEO and PPO segments of the triblock copolymer.

  7. The Structure of Water in PEO-Based Segmented Block Copolymers and its Effect on Transition Temperatures

    NARCIS (Netherlands)

    Husken, Debby; Gaymans, Reinoud J.

    2008-01-01

    The effect of water on block copolymers that contain hydrophilic PEO flexible segments is studied. The polyether phase consisted of either PEO or mixtures of PEO and hydrophobic PTMO, monodisperse crystallisable T6T6T was used as hard segments. Water absorption as a function of relative humidity and

  8. Thermoresponsive gelling behavior of concentrated alumina suspensions containing poly(acrylic acid) and PEO-PPO-PEO copolymer.

    Science.gov (United States)

    Kondo, Akira; Xu, Hui; Abe, Hiroya; Naito, Makio

    2012-05-01

    Thermoresponsive gelling behavior of concentrated alumina suspensions with poly(acrylic acid) (PAA) and triblock copolymer (PEO(101)-PPO(56)-PEO(101), Pluronic F127) was investigated as a function of PAA concentration (0.4-1.2 mass%) for ceramic solid free forming. The copolymer species assemble into micelles at temperatures above 15°C, yielding aqueous physical gel. In this study, the concentrated alumina aqueous suspensions (φ=35 vol%) were first prepared using the anionic dispersant of PAA, and then the copolymer species (10 mass%) were dissolved at a cooled temperature at 10°C. The addition of the copolymer species had a negligible influence on the adsorption state of PAA onto the alumina surfaces. The PAA concentration needed for the saturation adsorption on the alumina surfaces was ~0.6 mass%. When the PAA concentration was this value or slightly less, the suspension became gel state at 30°C from low viscous state at 10°C. The thermally induced alumina gel had excellent viscoelastic properties, and thereby the three dimensional periodic ceramic structures were successfully fabricated by a direct colloidal printing method that using the gels as "solid" inks at the room temperature. On the other hand, when it exceeded the saturation adsorption limit, the gelling behavior was not observed, indicating that the non-adsorbing PAA species may partly suppress the micellization of the copolymer on the heating.

  9. Nano- and macroscale structural and mechanical properties of in situ synthesized bacterial cellulose/PEO-b-PPO-b-PEO biocomposites.

    Science.gov (United States)

    Tercjak, Agnieszka; Gutierrez, Junkal; Barud, Hernane S; Domeneguetti, Rafael R; Ribeiro, Sidney J L

    2015-02-25

    Highly transparent biocomposite based on bacterial cellulose (BC) mat modified with poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) block copolymer (EPE) were fabricated in situ during biosynthesis of bacterial cellulose in a static culture from Gluconacetobacter xylinum. The effect of the addition to the culture medium of water-soluble EPE block copolymer on structure, morphology, crystallinity, and final properties of the novel biocomposites was investigated at nano- and macroscale. High compatibility between components was confirmed by ATR-FTIR indicating hydrogen bond formation between the OH group of BC and the PEO block of EPE block copolymer. Structural properties of EPE/BC biocomposites showed a strong effect of EPE block copolymer on the morphology of the BC mats. Thus, the increase of the EPE block copolymer content lead to the generation of spherulites of PEO block, clearly visualized using AFM and MO technique, changing crystallinity of the final EPE/BC biocomposites investigated by XRD. Generally, EPE/BC biocomposites maintain thermal stability and mechanical properties of the BC mat being 1 wt % EPE/BC biocomposite material with the best properties. Biosynthesis of EPE/BC composites open new strategy to the utilization of water-soluble block copolymers in the preparation of BC mat based biocomposites with tunable properties.

  10. Structure Formation of Ultrathin PEO Films at Solid Interfaces—Complex Pattern Formation by Dewetting and Crystallization.

    Science.gov (United States)

    Braun, Hans-Georg; Meyer, Evelyn

    2013-02-05

    The direct contact of ultrathin polymer films with a solid substrate may result in thin film rupture caused by dewetting. With crystallisable polymers such as polyethyleneoxide (PEO), molecular self-assembly into partial ordered lamella structures is studied as an additional source of pattern formation. Morphological features in ultrathin PEO films (thickness PEO molecules, n-alkylterminated (hydrophobic) PEO oligomers are investigated with respect to self-organization in ultrathin films. Morphological features characteristic for pure PEO are not changed by the presence of the n-alkylgroups.

  11. PEO-PPO-PEO Carriers for rAAV-Mediated Transduction of Human Articular Chondrocytes in Vitro and in a Human Osteochondral Defect Model.

    Science.gov (United States)

    Rey-Rico, Ana; Frisch, Janina; Venkatesan, Jagadesh Kumar; Schmitt, Gertrud; Rial-Hermida, Isabel; Taboada, Pablo; Concheiro, Angel; Madry, Henning; Alvarez-Lorenzo, Carmen; Cucchiarini, Magali

    2016-08-17

    Gene therapy is an attractive strategy for the durable treatment of human osteoarthritis (OA), a gradual, irreversible joint disease. Gene carriers based on the small human adeno-associated virus (AAV) exhibit major efficacy in modifying damaged human articular cartilage in situ over extended periods of time. Yet, clinical application of recombinant AAV (rAAV) vectors remains complicated by the presence of neutralizing antibodies against viral capsid elements in a majority of patients. The goal of this study was to evaluate the feasibility of delivering rAAV vectors to human OA chondrocytes in vitro and in an experimental model of osteochondral defect via polymeric micelles to protect gene transfer from experimental neutralization. Interaction of rAAV with micelles of linear (poloxamer PF68) or X-shaped (poloxamine T908) poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) copolymers (PEO-PPO-PEO micelles) was characterized by means of isothermal titration calorimetry. Micelle encapsulation allowed an increase in both the stability and bioactivity of rAAV vectors and promoted higher levels of safe transgene (lacZ) expression both in vitro and in experimental osteochondral defects compared with that of free vector treatment without detrimental effects on the biological activity of the cells or their phenotype. Remarkably, protection against antibody neutralization was also afforded when delivering rAAV via PEO-PPO-PEO micelles in all systems evaluated, especially when using T908. Altogether, these findings show the potential of PEO-PPO-PEO micelles as effective tools to improve current gene-based treatments for human OA.

  12. Modeling the Phase Behavior of PEO-PPO-PEO Surfactants in Carbon Dioxide Using the PC-SAFT Equation of State: Application to Dry Decontamination of Solid Substrates

    Energy Technology Data Exchange (ETDEWEB)

    Kleiner, M.; Sadowski, G. [Tech Univ Dortmund, Dept Biochem and Chem Engn, Lab Thermodynam, D-44227 Dortmund (Germany); Stoychev, I.; Galy, J. [CEA Marcoule, DEN, DTCD, SPDE, LFSM, 30 (France); Fournel, B. [CEA Marcoule, DEN, DTCD, DIR, 30 (France); Lacroix-Desmazes, P. [ENSCM, UM2, UM1, CNRS, Inst Charles Gerhardt, UMR IAM 5253, F-34296 Montpellier 5 (France)

    2009-05-15

    The phase behavior of several commercially available poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) block copolymers (PEO-PPO-PEO or Pluronics L) in compressed carbon dioxide has been investigated within the framework of dry nuclear decontamination. For this purpose, cloud points have been measured in the pressure and temperature range from P = (10 to 40) MPa and from T = (293 to 338) K, respectively. To find a reliable method for surfactant selection, the perturbed-chain statistical association fluid theory (PC-SAFT) equation of state (EoS) has been applied to model the experimental data. The pure-component and the respective homopolymer + CO{sub 2} binary interaction parameters have been fitted to liquid densities and to homopolymer + CO{sub 2} binary equilibrium data. The phase behavior of Pluronics L copolymers as a function of concentration, molar mass, and copolymer composition has been predicted very accurately using a constant PEO-PPO binary interaction parameter k(PEO-PPO) = 0.007. The P and SAFT model was also successfully applied to Pluronics R copolymers (PPO-PEO-PPO), although a different k(PEO-PPO) = -0.018 was required to match the experimental data. The model predictions have shown that Pluronics L copolymers with molar mass M {<=} 2750 g.mol{sup -1} and a PEO mass fraction in the copolymer of less than 30 % have sufficiently low cloud-point pressures and are therefore the most suitable for the decontamination process. (authors)

  13. Novel nanorods based on PANI / PEO polymers using electrospinning method

    Energy Technology Data Exchange (ETDEWEB)

    Al-Hazeem, Nabeel Z., E-mail: nabeelnano333@gmail.com [Nano-Optoelectronics Research and Technology Laboratory, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Ministry of Education, the General Directorate for Educational Anbar (Iraq); Ahmed, Naser M.; Matjafri, M. Z. [Nano-Optoelectronics Research and Technology Laboratory, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Sabah, Fayroz A. [Nano-Optoelectronics Research and Technology Laboratory, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Department of Electrical Engineering, College of Engineering, Al-Mustansiriya University, Baghdad (Iraq); Rasheed, Hiba S. [Nano-Optoelectronics Research and Technology Laboratory, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Department of Physics, College of Education, Al-Mustansiriya University, Baghdad (Iraq)

    2016-07-06

    In this work, we fabricated nanorods by applying an electric potential on poly (ethylene oxide) (PEO) and polyaniline (PANI) as a polymeric solution by electrospinning method. Testing was conducted on the samples by field emission scanning Electron microscope (FE-SEM), X-ray diffraction (XRD) and Photoluminescence. And the results showed the emergence of nanorods in the sample within glass substrate. Diameters of nanorods have ranged between (52.78-122.40)nm And a length of between (1.15 – 1.32)μm. The emergence of so the results are for the first time, never before was the fabrication of nanorods for polymers using the same method used in this research.

  14. Novel nanorods based on PANI / PEO polymers using electrospinning method

    Science.gov (United States)

    Al-Hazeem, Nabeel Z.; Ahmed, Naser M.; Matjafri, M. Z.; Sabah, Fayroz A.; Rasheed, Hiba S.

    2016-07-01

    In this work, we fabricated nanorods by applying an electric potential on poly (ethylene oxide) (PEO) and polyaniline (PANI) as a polymeric solution by electrospinning method. Testing was conducted on the samples by field emission scanning Electron microscope (FE-SEM), X-ray diffraction (XRD) and Photoluminescence. And the results showed the emergence of nanorods in the sample within glass substrate. Diameters of nanorods have ranged between (52.78-122.40)nm And a length of between (1.15 - 1.32)μm. The emergence of so the results are for the first time, never before was the fabrication of nanorods for polymers using the same method used in this research.

  15. Enhancement of ionic conductivity of PEO based polymer electrolyte by the addition of nanosize ceramic powders.

    Science.gov (United States)

    Wang, G X; Yang, L; Wang, J Z; Liu, H K; Dou, S X

    2005-07-01

    The ionic conductivity of polyethylene oxide (PEO) based solid polymer electrolytes (SPEs) has been improved by the addition of nanosize ceramic powders (TiO2 and AL2O3). The PEO based solid polymer electrolytes were prepared by the solution-casting method. Electrochemical measurement shows that the 10 wt% TiO2 PEO-LiClO4 polymer electrolyte has the best ionic conductivity (about 10(-4) S cm(-1) at 40-60 degrees C). The lithium transference number of the 10 wt% TiO2 PEO-LiClO4 polymer electrolyte was measured to be 0.47, which is much higher than that of bare PEO polymer electrolyte. Ac impedance testing shows that the interface resistance of ceramic-added PEO polymer electrolyte is stable. Linear sweep voltammetry measurement shows that the PEO polymer electrolytes are electrochemically stable in the voltage range of 2.0-5.0 V versus a Li/Li+ reference electrode.

  16. The Analysis of Pendolino (peo) Mutants Reveals Differences in the Fusigenic Potential among Drosophila Telomeres.

    Science.gov (United States)

    Cenci, Giovanni; Ciapponi, Laura; Marzullo, Marta; Raffa, Grazia D; Morciano, Patrizia; Raimondo, Domenico; Burla, Romina; Saggio, Isabella; Gatti, Maurizio

    2015-06-01

    Drosophila telomeres are sequence-independent structures that are maintained by transposition to chromosome ends of three specialized retroelements (HeT-A, TART and TAHRE; collectively designated as HTT) rather than telomerase activity. Fly telomeres are protected by the terminin complex (HOAP-HipHop-Moi-Ver) that localizes and functions exclusively at telomeres and by non-terminin proteins that do not serve telomere-specific functions. Although all Drosophila telomeres terminate with HTT arrays and are capped by terminin, they differ in the type of subtelomeric chromatin; the Y, XR, and 4L HTT are juxtaposed to constitutive heterochromatin, while the XL, 2L, 2R, 3L and 3R HTT are linked to the TAS repetitive sequences; the 4R HTT is associated with a chromatin that has features common to both euchromatin and heterochromatin. Here we show that mutations in pendolino (peo) cause telomeric fusions (TFs). The analysis of several peo mutant combinations showed that these TFs preferentially involve the Y, XR and 4th chromosome telomeres, a TF pattern never observed in the other 10 telomere-capping mutants so far characterized. peo encodes a non-terminin protein homologous to the E2 variant ubiquitin-conjugating enzymes. The Peo protein directly interacts with the terminin components, but peo mutations do not affect telomeric localization of HOAP, Moi, Ver and HP1a, suggesting that the peo-dependent telomere fusion phenotype is not due to loss of terminin from chromosome ends. peo mutants are also defective in DNA replication and PCNA recruitment. However, our results suggest that general defects in DNA replication are unable to induce TFs in Drosophila cells. We thus hypothesize that DNA replication in Peo-depleted cells results in specific fusigenic lesions concentrated in heterochromatin-associated telomeres. Alternatively, it is possible that Peo plays a dual function being independently required for DNA replication and telomere capping.

  17. The Analysis of Pendolino (peo Mutants Reveals Differences in the Fusigenic Potential among Drosophila Telomeres.

    Directory of Open Access Journals (Sweden)

    Giovanni Cenci

    2015-06-01

    Full Text Available Drosophila telomeres are sequence-independent structures that are maintained by transposition to chromosome ends of three specialized retroelements (HeT-A, TART and TAHRE; collectively designated as HTT rather than telomerase activity. Fly telomeres are protected by the terminin complex (HOAP-HipHop-Moi-Ver that localizes and functions exclusively at telomeres and by non-terminin proteins that do not serve telomere-specific functions. Although all Drosophila telomeres terminate with HTT arrays and are capped by terminin, they differ in the type of subtelomeric chromatin; the Y, XR, and 4L HTT are juxtaposed to constitutive heterochromatin, while the XL, 2L, 2R, 3L and 3R HTT are linked to the TAS repetitive sequences; the 4R HTT is associated with a chromatin that has features common to both euchromatin and heterochromatin. Here we show that mutations in pendolino (peo cause telomeric fusions (TFs. The analysis of several peo mutant combinations showed that these TFs preferentially involve the Y, XR and 4th chromosome telomeres, a TF pattern never observed in the other 10 telomere-capping mutants so far characterized. peo encodes a non-terminin protein homologous to the E2 variant ubiquitin-conjugating enzymes. The Peo protein directly interacts with the terminin components, but peo mutations do not affect telomeric localization of HOAP, Moi, Ver and HP1a, suggesting that the peo-dependent telomere fusion phenotype is not due to loss of terminin from chromosome ends. peo mutants are also defective in DNA replication and PCNA recruitment. However, our results suggest that general defects in DNA replication are unable to induce TFs in Drosophila cells. We thus hypothesize that DNA replication in Peo-depleted cells results in specific fusigenic lesions concentrated in heterochromatin-associated telomeres. Alternatively, it is possible that Peo plays a dual function being independently required for DNA replication and telomere capping.

  18. Effect of PEO coating on bubble behavior within a polycarbonate microchannel array: A model for hemodialysis.

    Science.gov (United States)

    Coblyn, Matthew; Truszkowska, Agnieszka; Mohammadi, Mahshid; Heintz, Keely; McGuire, Joseph; Sharp, Kendra; Jovanovic, Goran

    2016-07-01

    Obstruction of fluid flow by stationary bubbles in a microchannel hemodialyzer decreases filtration performance and increases damage to blood cells through flow maldistribution. A polyethylene oxide (PEO)-polybutadiene (PB)-polyethylene oxide surface modification, previously shown to reduce protein fouling and water/air contact angle in polycarbonate microchannel hemodialyzers, can improve microchannel wettability and may reduce bubble stagnation by lessening the resistive forces that compete with fluid flow. In this study, the effect of the PEO-PB-PEO coating on bubble retention in a microchannel array was investigated. Polycarbonate microchannel surfaces were coated with PEO-PB-PEO triblock polymer via radiolytic grafting. Channel obstruction was measured for coated and uncoated microchannels after injecting a short stream of air bubbles into the device under average nominal water velocities of 0.9 to 7.2 cm/s in the channels. The presence of the PEO coating reduced obstruction of microchannels by stationary bubbles within the range of 1.8 to 3.6 cm/s, average nominal velocity. Numerical simulations based on the lattice Boltzmann method indicate that beneficial effects may be due to the maintenance of a lubricating, thin liquid film around the bubble. The determined effective range of the PEO coating for bubble management serves as an important design constraint. These findings serve to validate the multiutility of the PEO-PB-PEO coating (bubble lubrication, biocompatibility, and therapeutic loading). © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 941-948, 2016.

  19. Preparation of Poly (ethylene oxide) (PEO) Modified Tungsten Oxide Hybrid Films via Sol-Gel Processing

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Poly (ethylene axide) (PEO) modified WO3 thin films were prepared on glass substrates with special temperature.The sol-gel transition proess was investigated by using DTA-TG,SEM and XRD.The electrochemical characteristic of the films was studied by cyclic voltmmetry measurement.The results show that PEO has heavy effects on the crystallization of WO3 during structure evolution because of the interaction between PEO and WO3.It increases the crystallization temperature of the gels and thus improves the electrochemical properties and cyclic life of WO3 film as electrochromic materials.

  20. Corrosion protection performance of single and dual Plasma Electrolytic Oxidation (PEO) coating for aerospace applications

    Energy Technology Data Exchange (ETDEWEB)

    Madhan Kumar, A., E-mail: princemadhank@gmail.com; Kwon, Sun Hwan; Jung, Hwa Chul; Shin, Kwang Seon

    2015-01-15

    Plasma Electrolytic Oxidation (PEO) coatings are known to be one of the most appropriate method for corrosion protection of magnesium (Mg) alloy. The improvement of PEO coatings and the optimization of their surface aspects are of major importance. In this current work, the influence of dual PEO coating on strip-cast AZ31 Mg alloy substrate has been evaluated with the aim of improving the surface and corrosion protection aspects. For this purpose, AZ31 Mg substrates are subjected to single and dual PEO processing in silicate and phosphate electrolyte under similar condition. Scanning electron microscopy (SEM) analysis confirmed that the number of pores in PEO coating processed in silicate electrolyte is higher than others. X-ray diffraction analysis of PEO coatings showed that the surface coating is mainly comprised of Mg{sub 2}SiO{sub 4}, Mg{sub 3}(PO{sub 4}){sub 2} and MgO with different quantity based on PEO processing. Compared with the AZ31 Mg, the corrosion potential (E{sub corr}) of both type PEO coatings was positively shifted about 250–400 mV and the corrosion current density (i{sub corr}) was lowered by 3-4 orders of magnitude as result of adequate corrosion protection to the Mg alloy in 3.5% NaCl solution. All of the observation obviously showed that the dual PEO coating provides better corrosion protection performance than their respective single due to its synergistic beneficial effect. - Highlights: • Influence of dual PEO coating on AZ31 Mg alloy substrate was evaluated. • XRD confirmed formation of thin MgO inner, Mg{sub 3}(PO{sub 4}){sub 2} and Mg{sub 2}SiO{sub 4} outer layer. • SEM results showed uniform coating with no cracks and relatively less micro pores. • Micro hardness of dual PEO coatings is higher than single PEO coatings. • Dual coating provides superior corrosion performance due to its synergistic effect.

  1. What can we learn from ionic conductivity measurements in polymer electrolytes? A case study on poly(ethylene oxide) (PEO)-NaI and PEO-LiTFSI.

    Science.gov (United States)

    Stolwijk, Nicolaas A; Wiencierz, Manfred; Heddier, Christian; Kösters, Johannes

    2012-03-15

    We explore in detail what information on ionic diffusivity and ion pairing can be exclusively gained from combining accurate direct-current conductivity data in polymer electrolytes with a novel evaluation model. The study was performed on two prototype systems based on poly(ethylene oxide) (PEO) with known disparate ion-association properties, which are due to the dissimilar salt components being either sodium iodide (NaI) or lithium bis(trifluoromethane-sulfonyl)imide (LiN(CF(3)SO(2))(2) or LiTFSI). The temperature dependence of the conductivity can be described by an extended Vogel-Tammann-Fulcher (VTF) equation, which involves a Boltzmann factor containing the pair-formation enthalpy ΔH(p). We find a distinct increase of the positive ΔH(p) values with decreasing salt concentration and similarly clear trends for the pertinent VTF parameters. The analysis further reveals that PEO-NaI combines a high pair fraction with a high diffusivity of the I(-) ion. By contrast, PEO-LiTFSI appears to be characterized by a low ion-pairing tendency and a relatively low mobility of the bulky TFSI(-) ion. The observed marked differences between PEO-NaI and PEO-LiTFSI complexes of homologous composition are most pronounced at high temperatures and low salt concentrations.

  2. Coarse-graining poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers using the MARTINI force field.

    Science.gov (United States)

    Nawaz, Selina; Carbone, Paola

    2014-02-13

    The MARTINI coarse-grain (CG) force field is extended for a class of triblock block copolymers known as Pluronics. Existing MARTINI bead types are used to model the non-bonded part of the potential while single chain properties for both homopolymers, poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO), are used to develop the bonded interactions. The new set of force field parameters reproduces structural and dynamical properties of high molecular weight homo- and copolymers. The CG model is moderately transferable in solvents of different polarity and concentration; however, the PEO homopolymer model presents a reduced thermodynamic transferability especially in water probably due to the lack of hydrogen bonds with the solvent. Our simulations of a monolayer of Pluronic L44 show polymer-brush-like characteristics for the PEO segments which protrude into the aqueous phase. Other membrane properties not easily accessible using experimental techniques such as its membrane thickness are also calculated.

  3. Plasma Electrolytic Oxidation (PEO) Coatings on an A356 Alloy for Improved Corrosion and Wear Resistance

    Science.gov (United States)

    Peng, Zhijing

    Plasma electrolytic oxidizing (PEO) is an advanced technique that has been used to deposit thick and hard ceramic coatings on aluminium (Al) alloys. This work was however to use the PEO process to produce thin ceramic oxide coatings on an A356 Al alloy for improving corrosion and wear resistance of the alloy. Effects of current density and treatment time on surface morphologies and thickness of the PEO coatings were investigated. The improvement of galvanic corrosion properties of the coated A356 alloy vs. steel and carbon fibre were evaluated in E85 fuel or NaCl environments. Tribological properties of the coatings were studied with comparison to the uncoated A356 substrate and other commercially-used engine bore materials. The research results indicated that the PEO coatings could have excellent tribological and corrosion properties for aluminium engine applications.

  4. Electrochemistry study on PEO-LiClO4-ZSM5 composite polymer electrolyte

    Institute of Scientific and Technical Information of China (English)

    XI Jingyu; MA Xiaomei; CUI Mengzhong; HUANG Xiaobin; ZHENG Zhen; TANG Xiaozhen

    2004-01-01

    A novel all solid-state composite polymer electrolyte, PEO-LiClO4-LiZSM5, by using "shape-selective" molecular sieves ZSM-5 as filler was obtained by the solvent casting method. The experimental results showed that the addition of LiZSM5 could enhance the ionic conductivity of the pristine PEO-LiClO4 electrolyte, the ionic conductivity of PEO10-LiClO4-10%LiZSM5 achieved 1.4×10-5 S cm-1 at 25℃. Lithium ion transference number was tested by AC impedance combined with the steady-state current method, the results showed that LiZSM5 could improve the Li+ transference number of the CPE effectively. The broad electrochemical stability window ensured the use of PEO-Li- ClO4-LiZSM5 as electrolyte materials for all solid-state rechargeable lithium ion batteries.

  5. CONDUCTIVITY STUDIES OF (PEO +KHCO3 SOLID ELECTROLYTE SYSTEM AND ITS APPLICATION AS AN ELECTROCHEMICAL CELL

    Directory of Open Access Journals (Sweden)

    K. VIJAY KUMAR

    2010-06-01

    Full Text Available Solid polymer electrolyte system, polyethylene oxide (PEO complexed with potassium bicarbonate (KHCO3 salt was prepared by solution-cast technique. Several experimental techniques such as infrared radiation (IR, differential scanning calorimeter (DSC, and composition dependence conductivity, temperature dependence conductivity in the temperature range of 308–368 K and transport number measurements were employed to characterize this polymer electrolyte system. The conductivity of the (PEO+KHCO3 electrolyte was found to be about 3 times larger than that of pure PEO at room temperature. The transference data indicated that the charge transport in these polymer electrolyte systems is predominantly due to K+ ions. Using this polymer electrolyte an electrochemical cell with configuration K+/(PEO+KHCO3/(I2+C+electrolyte was fabricated and its discharge characteristics are studied. A number of other cell parameters associated with the cell were evaluated and are reported in this paper.

  6. Adsorption, structural alteration and elution of peptides at pendant PEO layers.

    Science.gov (United States)

    Wu, Xiangming; Ryder, Matthew P; McGuire, Joseph; Schilke, Karl F

    2013-12-01

    An experimentally based, quantitative understanding of the entrapment and function of small peptides within PEO brush layers does not currently exist. Earlier work provided a rationale for expecting that an ordered, compact peptide will enter the PEO phase more readily than a peptide of similar size that adopts a less ordered, less compact form, and that amphiphilicity will promote peptide retention within the hydrophobic region of the PEO brush. Here we more deliberately describe criteria for peptide integration and structural change within the PEO brush, and discuss the reversibility of peptide entrapment with changing solvent conditions. For this purpose, circular dichroism (CD) was used to record the adsorption and conformational changes of (amphiphilic) WLBU2 and (non-amphiphilic) polyarginine peptides at uncoated (hydrophobic) and PEO-coated silica nanoparticles. Peptide conformation was controlled between disordered and α-helical forms by varying the concentration of perchlorate ion. We show an initially more ordered (α-helical) structure promotes peptide adsorption into the PEO layer. Further, a partially helical peptide undergoes an increase in helicity after entry, likely due to concomitant loss of capacity for peptide-solvent hydrogen bonding. Peptide interaction with the PEO chains resulted in entrapment and conformational change that was irreversible to elution with changing solution conditions in the case of the amphiphilic peptide. In contrast, the adsorption and conformational change of the non-amphiphilic peptide was reversible. These results indicate that responsive drug delivery systems based on peptide-loaded PEO layers can be controlled by modulation of solution conditions and peptide amphiphilicity.

  7. Immobilization of lipases in PSS/PEO blends and applications in esters synthesis; Imobilizacao de lipases em blendas de PSS/PEO e aplicacoes na sintese de esteres

    Energy Technology Data Exchange (ETDEWEB)

    Vecchia, Roberto D. [Universidade do Vale do Itajai (UNIVALI), Florianopolis, SC (Brazil). Nucleo de Investigacoes Quimico-Farmaceuticas (NIQFAR)]. E-mail: rdv@ccs.univali.br; Nascimento, Maria G.; Soldi, Valdir [Santa Catarina Univ., Florianopolis, SC (Brazil). Dept. de Quimica]. E-mail: graca@qmc.ufsc.br; vsoldi@qmc.ufsc.br

    2001-07-01

    Various lipases were immobilized in PSS/PEO blends and used as bio catalysts in the esterification reaction of lauric acid with n-pentanol, in hexane as a solvent for 24 h at 35 deg C. The best results in the ester conversion, were obtained by using lipase from Rhryzopus oryzae immobilized in PSS/PEO 80:20 blend. The data are in agreement with DSC and TGA values, which showed that these systems (blend/lipase) were very stable with low mass loss. No product was obtained by using lipase FAP-15 immobilized in PSS film , showing the strong influence of the polymer on enzyme activity. (author)

  8. PVP-b-PEO block copolymers for stable aqueous and ethanolic graphene dispersions.

    Science.gov (United States)

    Perumal, Suguna; Park, Kyung Tae; Lee, Hyang Moo; Cheong, In Woo

    2016-02-15

    The ability to disperse pristine (unfunctionalized) graphene is important for various applications, coating, nanocomposites, and energy related systems. Herein we report that amphiphilic copolymers of poly(4-vinyl pyridine)-block-poly(ethylene oxide) (PVP-b-PEO) are able to disperse graphene with high concentrations about 2.6mg/mL via sonication and centrifugation. Ethanolic and aqueous highly-ordered pyrolytic graphite (HOPG) dispersions with block copolymers were prepared and they were compared with the dispersions stabilized by P-123 Pluronic® (P123) and poly(styrene)-block-poly(ethylene oxide) (PS-b-PEO) synthesized. Transmission electron microscopy, scanning electron microscopy, atomic force microscopy, X-ray diffraction, Raman and UV-visible spectroscopic studies confirmed that PVP-b-PEO block copolymers are better stabilizers for HOPG graphene than P123 and PS-b-PEO. X-ray photoelectron spectroscopy and force-distance (F-d) curve analyses revealed that the nitrogen of vinyl pyridine plays a vital role in better attractive interaction with surface of graphene sheet. Thermogravimetric analysis showed that larger amount of PVP-b-PEO was adsorbed onto graphene with longer poly(4-vinyl pyridine) (PVP) block length and in aqueous medium, respectively, and which was consistent with electrical conductivity decreases. This study presents the dispersion efficiency of graphene using PVP-b-PEO varies substantially depending on the lengths of their hydrophobic (PVP) domains.

  9. Local thermomechanical analysis of a microphase-separated thin lamellar PS-b-PEO film.

    Science.gov (United States)

    Rice, Reginald H; Mokarian-Tabari, Parvaneh; King, William P; Szoszkiewicz, Robert

    2012-09-18

    We use atomic force microscopy (AFM) and hot tip AFM (HT-AFM) to thermophysically characterize a 30 nm thick film of poly(styrene-block-ethylene oxide), PS-b-PEO, and to modify its lamellar patterns having spacing of 39 ± 3 nm. AFM tip scans of the polymer film induce either abrasive surface patterns or nanoscale ripples, which depend upon the tip force, temperature, and number of scans. The evolution of the lamellar patterns is explained by the polymer film molecular structure and mode I crack propagation in the polymer combined with the stick-and-slip behavior of the AFM tip. The HT-AFM measurements at various tip-sample temperatures and scanning speeds yield several thermophysical quantities: the PEO melting temperature of 54 ± 12 °C, the PS glass transition temperature of 54 ± 12 °C, the PS-b-PEO specific heat of 3.6 ± 2.7 J g(-1) K(-1), the PEO melting enthalpy of 111 ± 88 J g(-1), and the free energy of Helmholtz for PEO unfolding (and melting) of 10(-20) J nm(-2). These quantities are obtained for PS-b-PEO volumes of 30,000 nm(3), which correspond to 30 ag of the polymer.

  10. Polyethylene oxide (PEO)-hyaluronic acid (HA) nanofibers with kanamycin inhibits the growth of Listeria monocytogenes.

    Science.gov (United States)

    Ahire, J J; Robertson, D D; van Reenen, A J; Dicks, L M T

    2017-02-01

    Listeria monocytogenes is well known to cause prosthetic joint infections in immunocompromised patients. In this study, polyethylene oxide (PEO) nanofibers, containing kanamycin and hyaluronic acid (HA), were prepared by electrospinning at a constant electric field of 10kV. PEO nanofibers spun with 0.2% (w/v) HA and 1% (w/v) kanamycin had a smooth, bead-free structure at 30-35% relative humidity. The average diameter of the nanofibers was 83±20nm. Attenuated total reflectance (ATR)-Fourier transform infrared (FTIR) spectroscopy indicated that kanamycin was successfully incorporated into PEO/HA matrix. The presence of kanamycin affects the thermal properties of PEO/HA nanofibers, as shown by differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA). The kanamycin-PEO-HA nanofibers (1mg; 47±3μg kanamycin) inhibited the growth of L. monocytogenes EDGe by 62%, as compared with PEO-HA nanofibers, suggesting that it may be used to coat prosthetic implants to prevent secondary infections.

  11. Surface characterisation of Ti–15Mo alloy modified by a PEO process in various suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Kazek-Kęsik, Alicja [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego Street 6, 44-100 Gliwice (Poland); Dercz, Grzegorz [Institute of Materials Science, University of Silesia, 75 Pułku Piechoty Street 1 A, 41-500 Chorzow (Poland); Kalemba, Izabela [Faculty of Metals Engineering and Industrial Computer Science, AGH University of Science and Technology, Mickiewicza Street 30, 30-059 Krakow (Poland); Suchanek, Katarzyna [The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego Street 152, 31-342 Krakow (Poland); Kukharenko, Andrey I.; Korotin, Danila M. [Institute of Metal Physics, Russian Academy of Sciences-Ural Division, S. Kovalevskoi Street 18, 620990 Yekaterinburg (Russian Federation); Ural Federal University, Mira Street 19, 620002 Yekaterinburg (Russian Federation); Michalska, Joanna [Faculty of Materials Science and Metallurgy, Silesian University of Technology, Krasińskiego Street 8, 40-019 Katowice (Poland); Krząkała, Agnieszka; Piotrowski, Jerzy [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego Street 6, 44-100 Gliwice (Poland); Kurmaev, Ernst Z. [Institute of Metal Physics, Russian Academy of Sciences-Ural Division, S. Kovalevskoi Street 18, 620990 Yekaterinburg (Russian Federation); Cholakh, Seif O. [Ural Federal University, Mira Street 19, 620002 Yekaterinburg (Russian Federation); Simka, Wojciech, E-mail: wojciech.simka@polsl.pl [Faculty of Chemistry, Silesian University of Technology, B. Krzywoustego Street 6, 44-100 Gliwice (Poland)

    2014-06-01

    This paper reports on the surface modification of a Ti–15Mo alloy by plasma electrolytic oxidation (PEO). This process was carried out in solutions of 0.1 M Ca(H{sub 2}PO{sub 2}){sub 2} with various concentrations of tricalcium phosphate (Ca{sub 3}(PO{sub 4}){sub 2}), wollastonite (CaSiO{sub 3}), or silica (SiO{sub 2}) using voltages of up to 350 V. The surface microstructure (SEM, cross-section of coating), roughness and chemical composition (energy-dispersive X-ray spectroscopy, thin layer X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy) of the porous oxide layers were investigated. The concentration of powder added to the solution changed the chemical composition and morphology of PEO coatings on the Ti–15Mo alloy surface. Calcium and phosphorous compounds were detected in the coatings formed on the substrate by the PEO process at 300 V. - Highlights: • Porous coatings were formed on β-type Ti–15Mo alloy by PEO process. • Bioactive compounds were incorporated into PEO coatings on the substrate. • Influence of PEO parameters on oxide layer properties was presented.

  12. Biodegradable amphiphilic block copolymers containing functionalized PEO blocks:Controlled synthesis and biomedical potentials

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A series of controllable amphiphilic block copolymers composed of poly(ethylene oxide)(PEO) as the hydrophilic block and poly(ε-caprolactone)(PCL) as the hydrophobic block with the amino terminal group at the end of the PEO chain(PCL-b-PEO-NH2) were synthesized.Based on the further reaction of reactive amino groups,diblock copolymers with functional carboxyl groups(PCL-b-PEO-COOH) and functional compounds RGD(PCL-b-PEO-RGD) as well as the triblock copolymers with thermosensitive PNIPAAm blocks(PCL-b-PEO-b-PNIPAAM) were synthesized.The well-controlled structures of these copolymers with functional groups and blocks were characterized by gel permeation chromatography(GPC) and 1H NMR spectroscopy.These copolymers with functionalized hydrophilic blocks were fabricated into microspheres for the examination of biofunctions via cell culture experiments and in vitro drug release.The results indicated the significance of introducing functional groups(e.g.,NH2,COOH and RGD) into the end of the hydrophilic block of amphiphilic block copolymers for biomedical potentials in tissue engineering and controlled drug release.

  13. Core-shell structured PEO-chitosan nanofibers by coaxial electrospinning.

    Science.gov (United States)

    Pakravan, Mehdi; Heuzey, Marie-Claude; Ajji, Abdellah

    2012-02-13

    Core-shell structured PEO-chitosan nanofibers have been produced using a coaxial electrospinning setup. PEO and chitosan solutions, both in an aqueous acetic acid solvent, were used as the inner (core) and outer (shell) layer, respectively. Uniform-sized defect-free nanofibers of 150-190 nm diameter were produced. In addition, hollow nanofibers could be obtained subsequent to PEO washing of the membranes. The core-shell nanostructure and existence of chitosan on the shell layer were confirmed by TEM images obtained before and after washing the PEO content with water. The presence of chitosan on the surface of the composite nanofibers was further supported by XPS studies. The chitosan and PEO compositions in the nanofibrous mats were determined by TGA analysis, which were similar to their ratio in the feed solutions. The local compositional homogeneity of the membranes and the efficiency of the washing step to remove PEO were also verified by FTIR. In addition, DSC and XRD were used to characterize the crystalline structure and morphology of the co-electrospun nonwoven mats. The prepared coaxial nanofibers (hollow and solid) have several potential applications due to the presence of chitosan on their outer surfaces.

  14. Structures of PEP–PEO Block Copolymer Micelles: Effects of Changing Solvent and PEO Length and Comparison to a Thermodynamic Model

    DEFF Research Database (Denmark)

    Jensen, Grethe Vestergaard; Shi, Qing; Deen, G. Roshan

    2012-01-01

    Structures of poly(ethylene propylene)–poly(ethylene oxide) (PEP–PEO) block copolymer micelles were determined from small-angle X-ray scattering and static light scattering and compared to predictions from a thermodynamic model. Both the corona block length and the solvent water–ethanol ratio were...

  15. New triblock copolymer templates, PEO-PB-PEO, for the synthesis of titania films with controlled mesopore size, wall thickness, and bimodal porosity.

    Science.gov (United States)

    Ortel, Erik; Fischer, Anna; Chuenchom, Laemthong; Polte, Jörg; Emmerling, Franziska; Smarsly, Bernd; Kraehnert, Ralph

    2012-01-23

    The synthesis and properties of a series of new structure-directing triblock copolymers with PEO-PB-PEO structure (PEO = poly(ethylene oxide) and PB = polybutadiene) and their application as superior pore-templates for the preparation of mesoporous titania coatings are reported. Starting from either TiCl4 or from preformed TiO2 nanocrystalline building blocks, mesoporous crystalline titanium oxide films with a significant degree of mesoscopic ordered pores are derived, and the pore size can be controlled by the molecular mass of the template polymer. Moreover, the triblock copolymers form stable micelles already at very low concentration, i.e., prior to solvent evaporation during the evaporation-induced self-assembly process (EISA). Consequently, the thickness of pore walls can be controlled independently of pore size by changing the polymer-to-precursor ratio. Thus, unprecedented control of wall thickness in the structure of mesoporous oxide coatings is achieved. In addition, the micelle formation of the new template polymers is sufficiently distinct from that of typical commercial PPO-PEO-PPO polymers (Pluronics; PPO = poly(propylene oxide)), so that a combination of both polymers facilitates bimodal porosity via dual micelle templating.

  16. Quartz crystal microbalance study of ionic strength and pH-dependent polymer conformation and protein adsorption/desorption on PAA, PEO, and mixed PEO/PAA brushes.

    Science.gov (United States)

    Delcroix, M F; Demoustier-Champagne, S; Dupont-Gillain, C C

    2014-01-14

    The conformation of polymer chains grafted on a substrate influences protein adsorption. In a previous study, adsorption/desorption of albumin was demonstrated on mixed poly(ethylene oxide) (PEO)/poly(acrylic acid) (PAA) brushes, triggered by solutions of adequate pH and ionic strength (I). In the present work, homolayers of PEO or PAA are submitted to saline solutions with pH from 3 to 9 and I from 10(-5) to 10(-1) M, and their conformation is evaluated in real time using quartz crystal microbalance with dissipation monitoring (QCM-D). Shrinkage/swelling of PAA chains and hydration and salt condensation in the brush are evidenced. The adsorption of human serum albumin (HSA) onto such brushes is also monitored in these different saline solutions, leading to a deep understanding of the influence of polymer chain conformation, modulated by pH and I, on protein adsorption. A detailed model of the conformation of PEO/PAA mixed brushes depending on pH and I is then proposed, providing a rationale for the identification of conditions for the successive adsorption and desorption of proteins on such mixed brushes. The adsorption/desorption of albumin on PEO/PAA is demonstrated using QCM-D.

  17. Immobilizing PEO-PPO-PEO triblock copolymers on hydrophobic surfaces and its effect on protein and platelet: a combined study using QCM-D and DPI.

    Science.gov (United States)

    Jin, Jing; Huang, Fujian; Hu, Yu; Jiang, Wei; Ji, Xiangling; Liang, Haojun; Yin, Jinghua

    2014-11-01

    Dual polarization interferometry was used to monitor the immobilization dynamics of four Pluronics on hydrophobic surfaces and to elucidate the effect of Pluronic conformation on protein adsorption. The proportion of hydrophobic chain segments and not the length of the hydrophobic chain can influence the chain densities of the Pluronics. The immobilized densities of the Pluronics resulted from competition between the hydration of polyethylene oxide (PEO) in the aqueous solution and the hydrophobic interaction of polypropylene oxide on the substrate. P-123 obtained the largest graft mass (2.89±0.25 ng/mm2) because of the dominant effect of hydrophobic interactions. Hydrophobic segments of P-123 were anchored slowly and step-wise on the C18 substrate. P-123 exhibited the largest hydrophobic chain segment proportion (propylene oxide/ethylene oxide=3.63) and formed a brush chain conformation, indicating excellent protein and platelet resistance. The result of quartz crystal microbalance with dissipation further confirmed that the PEO conformation in P-123 on the substrate exhibited a relatively extended brush chain, and that L-35 showed relatively loose and pancake-like structures. The PEO in P-123 regulated the conformation to maintain the native conformation and resist the adsorption of bovine serum albumin (BSA). Thus, the hemocompatibilities of the immobilized Pluronics were influenced by the proportion of hydrophobic chain segments and their PEO conformations.

  18. Mesoscopic Simulations of Adsorption and Association of PEO-PPO-PEO Triblock Copolymers on a Hydrophobic Surface: From Mushroom Hemisphere to Rectangle Brush.

    Science.gov (United States)

    Song, Xianyu; Zhao, Shuangliang; Fang, Shenwen; Ma, Yongzhang; Duan, Ming

    2016-11-08

    The dissipative particle dynamics (DPD) method is used to investigate the adsorption behavior of PEO-PPO-PEO triblock copolymers at the liquid/solid interface. The effect of molecular architecture on the self-assembled monolayer adsorption of PEO-PPO-PEO triblock copolymers on hydrophobic surfaces is elucidated by the adsorption process, film properties, and adsorption morphologies. The adsorption thicknesses on hydrophobic surfaces and the diffusion coefficient as well as the aggregation number of Pluronic copolymers in aqueous solution observed in our simulations agree well with previous experimental and numerical observations. The radial distribution function revealed that the ability of self-assembly on hydrophobic surfaces is P123 > P84 > L64 > P105 > F127, which increased with the EO ratio of the Pluronic copolymers. Moreover, the shape parameter and the degree of anisotropy increase with increasing molecular weight and mole ratio of PO of the Pluronic copolymers. Depending on the conformation of different Pluronic copolymers, the morphology transition of three regimes on hydrophobic surfaces is present: mushroom or hemisphere, progressively semiellipsoid, and rectangle brush regimes induced by decreasing molecular weight and mole ratio of EO of Pluronic copolymers.

  19. Bonding properties of PEO-LiClO4 and Al%PEO-LiClO4与 Al 的键合性能

    Institute of Scientific and Technical Information of China (English)

    吴常雄; 刘翠荣; 吴志生; 阴旭

    2015-01-01

    To improve the packaging quality of the micro-electro-mechanical systems (MEMS),the solid polymer electrolyte (PEO-LiClO4 )was designed as a new material to bond with anode Al.The application of polymer solid electrolyte in anodic bond-ing package was mainly due to its ionic conductivity.FTIR,XRD,super depth of field optical microscopy and SEM were used to investigate the conductive mechanism of PEO-LiClO4 ,the effects of adding different lithium salts on its electrical conductivity, and the combination of bonding interface.The results show that compared with the LiPF6 and LiBF4 ,reactions between LiClO4 and PEO are more likely to weaken the complex structure and make it much looser;with the action of a strong electrostatic field, the diffusion and migration of lithium ions can be promoted.The conductive mechanism of PEO-LiClO4 lies in that the Li+is first-ly dissociated with ClO-4 and then forms complexation with C—O;the transition layers formed by a chemical reaction at the bond-ing interface is the key for the bonding of PEO-LiClO4 and aluminum.%为了提高微机电系统(MEMS)的封装质量,设计了应用高分子固体电解质(PEO-LiClO4)作为新材料并与 Al 进行阳极键合。高分子固体电解质能用于阳极键合封装主要是因为它具有离子导电性。采用红外光谱(FTIR)、X 射线衍射(XRD)、超景深光学显微镜观察、扫描电子显微镜(SEM)等方法研究了 PEO-LiClO4的导电机理,加入不同锂盐对其导电性的影响及其键合界面的结合情况。结果表明:相对于 LiPF6和 LiBF4,LiClO4与 PEO 发生的反应更容易削弱络合结构,使络合结构松散,在强静电场的作用下,促进了锂离子的扩散和迁移;PEO-LiClO4的导电机理是 Li+先与 ClO-4离解,然后与 C—O 产生络合;键合界面发生化学反应形成的过渡层是 PEO-LiClO4与 Al 能够键合的关键。

  20. Biodegradable polymer for sealing porous PEO layer on pure magnesium: An in vitro degradation study

    Energy Technology Data Exchange (ETDEWEB)

    Alabbasi, Alyaa; Mehjabeen, Afrin [Biomaterials and Engineering Materials (BEM) Laboratory, James Cook University, Townsville 4811, Queensland (Australia); Kannan, M. Bobby, E-mail: bobby.mathan@jcu.edu.au [Biomaterials and Engineering Materials (BEM) Laboratory, James Cook University, Townsville 4811, Queensland (Australia); Ye, Qingsong [Discipline of Dentistry, James Cook University, Townsville 4811, Queensland (Australia); Blawert, Carsten [Magnesium Innovation Centre, Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Geesthacht 21502 (Germany)

    2014-05-01

    Graphical abstract: - Highlights: • Poly(L-lactide) was used to seal the porous PEO layer on Mg. • The dual-layer coating improved the in vitro degradation resistance of Mg. • Localized degradation was inhibited in the dual-layer coated Mg. - Abstract: An attempt was made to seal the porous silicate-based plasma electrolytic oxidation (PEO) layer on pure magnesium (Mg) with a biodegradable polymer, poly(L-lactide) (PLLA), to delay the localized degradation of magnesium-based implants in body fluid for better in-service mechanical integrity. Firstly, a silicate-based PEO coating on pure magnesium was performed using a pulsed constant current method. In order to seal the pores in the PEO layer, PLLA was coated using a two-step spin coating method. The performance of the PEO–PLLA Mg was evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The EIS results showed that the polarization resistance (R{sub p}) of the PEO–PLLA Mg was close to two orders of magnitude higher than that of the PEO Mg. While the corrosion current density (i{sub corr}) of the pure Mg was reduced by 65% with the PEO coating, the PEO–PLLA coating reduced the i{sub corr} by almost 100%. As expected, the R{sub p} of the PEO–PLLA Mg decreased with increase in exposure time. However, it was noted that the R{sub p} of the PEO–PLLA Mg even after 100 h was six times higher than that of the PEO Mg after 48 h exposure, and did not show any visible localized attack.

  1. Synthesis of PEO-PPO-PEO coated multi-functional CoFeAu nanoparticles by polyol process%Polyol法制备 PEO-PPO-PEO包裹的多功能CoFeAu纳米粒子

    Institute of Scientific and Technical Information of China (English)

    邵红琴; 张晓燕; 侯澎; 吴君华; 刘红玲

    2013-01-01

      采用Polyol合成法,以三嵌段共聚物PEO-PPO-PEO为表面活性剂,以1,2-十六烷二醇为还原剂,乙酰丙酮钴(Ⅱ)、乙酰丙酮铁(Ⅱ)和醋酸金为前驱体,成功合成了CoFeAu纳米粒子.傅立叶变换红外光谱(FT-IR)分析证实了共聚物PEO-PPO-PEO包裹在CoFeAu纳米颗粒表面,X射线衍射仪(XRD)测试得出该纳米粒子是面心立方晶体结构、晶格参数为0.406 nm、结晶性能好.紫外可见近红外分光光度计吸收光谱仪和振动样品磁强计(VSM )测试证明了该纳米粒子兼具良好的光学和磁学特性.该多功能CoFeAu纳米粒子有望在催化材料、磁材料、光电和生物医药等方面发挥有益作用.%CoFeAu nanoparticles were successfully synthesized by polyol process with the use of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) as the sur-factant ,C14 H29CH(OH)CH2OH as the reducing agent ,cobalt acetylacetonate ,iron acetylacet-onate and gold acetate as precursors .The FT-IR study confirmed the PEO-PPO-PEO molecules on the surface of the CoFeAu nanoparticles .The X-ray diffraction identified the crystallograph-ic parameter 0 .406 nm of the face-centered cubic structure and showed the nanoparticles have good crystallinity .Whereas a UV-Vis near IR spectrophotometer and a vibrating sample mag-netometer were respectively applied to prove the good optical and magnetic properties of the CoFeAu nanoparticles .Such multi-functional CoFeAu nanoparticles show promising applica-tions in the catalytic ,magnetic ,photoelectric and biomedical fields .

  2. Suppression of Lithium Dendrite Formation by Using LAGP-PEO (LiTFSI) Composite Solid Electrolyte and Lithium Metal Anode Modified by PEO (LiTFSI) in All-Solid-State Lithium Batteries.

    Science.gov (United States)

    Wang, Chunhua; Yang, Yifu; Liu, Xingjiang; Zhong, Hai; Xu, Han; Xu, Zhibin; Shao, Huixia; Ding, Fei

    2017-04-19

    The formation of lithium dendrites is suppressed using a Li1.5Al0.5Ge1.5(PO4)3-poly(ethylene oxide) (LAGP-PEO) composite solid electrolyte and a PEO (lithium bis(trifluoromethane)sulfonimide) [PEO (LiTFSI)]-modified lithium metal anode in all-solid-state lithium batteries. The effects on the anode performance based on the PEO content in the composite solid electrolyte and the molecular weight of PEO used to modify the Li anode are studied. The structure, surface morphology, and stability of the composite solid electrolyte are examined by X-ray diffraction spectroscopy, scanning electron microscopy, and electrochemical tests. Results show that the presence of a PEO-500000(LiTFSI) film on a Li anode results in good mechanical properties and satisfactory interface contact features. The film can also prevent Li from reacting with LAGP. Furthermore, the formation of lithium dendrites can be effectively inhibited as the composite solid electrolyte is combined with the PEO film on the Li anode. The ratio of PEO in the composite solid electrolyte can be reduced to a low level of 1 wt %. PEO remains stable even at a high potential of 5.12 V (vs Li/Li(+)). The assembled Li-PEO (LiTFSI)/LAGP-PEO/LiMn0.8Fe0.2PO4 all-solid-state cell can deliver an initial discharge capacity of 160.8 mAh g(-1) and exhibit good cycling stability and rate performance at 50 °C.

  3. PAA/PEO comb polymer effects on the rheological property evolution in concentrated cement suspensions

    Science.gov (United States)

    Kirby, Glen Harold

    We have studied the behavior of polyelectrolyte-based comb polymers in dilute solution and on the rheological property evolution of concentrated Portland cement suspensions. These species consisted of charge-neutral, poly(ethylene oxide) (PEO) "teeth" grafted onto a poly(acrylic acid) (PAA) "backbone" that contains one ionizable carboxylic acid group (COOH) per monomer unit. As a benchmark, our observations were compared to those obtained for pure cement pastes and systems containing pure polyelectrolyte species, i.e., sulfonated naphthalene formaldehyde (SNF) and poly(acrylic acid) (PAA). The behavior of PAA/PEO comb polymers, SNF, and PAA in dilute solution was studied as a function of pH in the absence and presence of mono-, di-, and trivalent counterions. Light scattering and turbidity measurements were carried out to assess their hydrodynamic radius and stability in aqueous solution, respectively. PAA experienced large conformational changes as a function of solution pH and ionic strength. Moreover, dilute solutions of ionized SNF and PAA species became unstable in the presence of multivalent counterions due to ion-bridging interactions. PAA/PEO solutions exhibited enhanced stability relative to pure polyelectrolytes under analogous conditions. The charge neutral PEO teeth shielded the underlying PAA backbone from ion-bridging interactions. In addition, such species hindered conformational changes in solution due to steric interactions between adjacent teeth. A new oscillatory shear technique was developed to probe the rheological property evolution of concentrated cement systems. The rheological property evolution of ordinary and white Portland cement systems were studied in the absence and presence of pure polyelectrolytes and PAA/PEO comb polymers with a wide range of PAA backbone molecular weight, PEO teeth molecular weight, and acid:imide ratio. Cement-PAA suspensions experienced rapid irreversible stiffening and set at 6 min due to ion

  4. High ionic conductivity P(VDF-TrFE)/PEO blended polymer electrolytes for solid electrochromic devices.

    Science.gov (United States)

    Nguyen, Chien A; Xiong, Shanxin; Ma, Jan; Lu, Xuehong; Lee, Pooi See

    2011-08-07

    Solid polymer electrolytes with excellent ionic conductivity (above 10(-4) S cm(-1)), which result in high optical modulation for solid electrochromic (EC) devices are presented. The combination of a polar host matrix poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) and a solid plasticized of a low molecular weight poly(ethylene oxide) (PEO) (M(w)≤ 20,000) blended polymer electrolyte serves to enhance both the dissolution of lithium salt and the ionic transport. Calorimetric measurement shows a reduced crystallization due to a better intermixing of the polymers with small molecular weight PEO. Vibrational spectroscopy identifies the presence of free ions and ion pairs in the electrolytes with PEO of M(w)≤ 8000. The ionic dissolution is improved using PEO as a plasticizer when compared to liquid propylene carbonate, evidently shown in the transference number analysis. Ionic transport follows the Arrhenius equation with a low activation energy (0.16-0.2 eV), leading to high ionic conductivities. Solid electrochromic devices fabricated with the blended P(VDF-TrFE)/PEO electrolytes and polyaniline show good spectroelectrochemical performance in the visible (300-800 nm) and near-infrared (0.9-2.4 μm) regions with a modulation up to 60% and fast switching speed of below 20 seconds. The successful introduction of the solid polymer electrolytes with its best harnessed qualities helps to expedite the application of various electrochemical devices. This journal is © the Owner Societies 2011

  5. Thermal and morphological behavior of chitosan/PEO blends containing gold nanoparticles. Experimental and theoretical studies.

    Science.gov (United States)

    Bonardd, Sebastián; Schmidt, Mathias; Saavedra-Torres, Mario; Leiva, Angel; Radic, Deodato; Saldías, César

    2016-06-25

    Using solution-casting method, binary blends of chitosan (CS) and poly (ethylene oxide) (PEO 100,000) containing Au nanoparticles (AuNPs) were prepared. Shifts in the melting temperature (Tm) and crystallization temperature (Tc) values for CS/PEO and CS/PEO/AuNPs blends were observed by calorimetric analysis. In general, CS/PEO/AuNPs blends tended to decompose at higher temperatures than neat polymers. From the FT-IR spectra, shifts in the main signals, such as -NH2, -OH and COC, were detected in the blends and were attributed to the polymer interactions and the incorporation of gold nanoparticles. In addition, the analysis of the blend topographies by atomic force microscopy (AFM) showed that at a higher CS content, more homogenous surfaces were observed. This behavior was attributed to the interactions present in the CS/PEO/AuNPs blends. Finally, theoretical analyses helped to confirm that the gold nanoparticles would be preferentially adsorbed onto the chitosan microdomains due to the interactions between acetyl and hydroxyl groups and Au atoms.

  6. Electrospun PHBV/PEO co-solution blends: microstructure, thermal and mechanical properties.

    Science.gov (United States)

    Bianco, Alessandra; Calderone, Manuela; Cacciotti, Ilaria

    2013-04-01

    Blending allows to tailor and modulate the properties of selected polymers. Blends of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and polyethylene oxide (PEO) were fabricated by electrospinning in different weight ratios i.e. 100:0, 80:20, 70:30, 50:50, 0:100. In order to evaluate the influence of PEO addition on the final properties of PHBV, a complete microstructural, thermal and mechanical characterization of PHBV/PEO blends has been performed. The two neat polymeric membranes were also considered for the sake of comparison. The following characterization techniques were employed: scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), Fourier transform infrared attenuated total reflectance (FTIR-ATR) spectroscopy, simultaneous thermogravimetric and differential analyses (TG-DTA), differential scanning calorimetry (DSC), and uniaxial tensile tests. All electrospun mats consisted of randomly oriented and uniform fibers. It has been observed that the microstructure of PHBV/PEO was remarkably affected by blend composition. The average fiber size ranged between 0.5 μm and 2.6 μm. It resulted that the electrospun polymeric blends consisted of separate crystalline domains associated to an amorphous interdisperse phase. PHBV/PEO blends presented intermediate mechanical properties, in terms of tensile modulus and ultimate tensile stress, with respect to the two neat components.

  7. Hydrophilic block azidation of PCL-b-PEO block copolymers from epichlorohydrin.

    Science.gov (United States)

    Liu, Junjie; Gan, Zhihua

    2014-05-01

    Amphiphilic diblock copolymers poly(ϵ-caprolactone)-b-poly(ethylene oxide) (PCL-b-PEO) with well-controlled pendant azido groups along the hydrophilic PEO block, that is, poly(ϵ-caprolactone)-b-poly(ethylene oxide-co-glycidyl azide) (PCL-b-P(EO-co-GA)), are synthesized from poly(ϵ-caprolactone)-b-poly(ethylene oxide-co-epichlorohydrin) (PCL-b-P(EO-co-ECH)). The further conversion of those azido groups along the hydrophilic block of copolymers into amino or carboxyl groups via click chemistry is studied. The micelles self-assembled from PCL-b-P(EO-co-GA) with azido groups on the shell are crosslinked by the dialkynyl-PEO. The micelles with crosslinked shell show better stability, higher drug loading capacities, subsequent faster drug release rate, and higher cytotoxicity to cancer cells. The introduction of azido groups into PCL-b-PEO amphiphilic diblock copolymers from epichlorohydrin in PEO hydrophilic block in this work provides a new method for biofunctionalization of micelles via mild click chemistry.

  8. The production of PEO polymer brushes via Langmuir-Blodgett and Langmuir-Schaeffer methods: incomplete transfer and its consequences.

    Science.gov (United States)

    de Vos, Wiebe M; de Keizer, Arie; Kleijn, J Mieke; Cohen Stuart, Martien A

    2009-04-21

    Using fixed-angle ellipsometry, we investigate the degree of mass transfer upon vertically dipping a polystyrene surface through a layer of a polystyrene-poly(ethylene oxide) (PS-PEO) block copolymer at the air water interface (Langmuir-Blodgett or LB transfer). The transferred mass is proportional to the PS-PEO grafting density at the air-water interface, but the transferred mass is not equal to the mass at the air-water interface. We find that depending on the chain length of the PEO block only a certain fraction of the polymers at the air-water interface is transferred to the solid surface. For the shortest PEO chain length (PS36-PEO148), the mass transfer amounts to 94%, while for longer chain lengths (PS36-PEO370 and PS38-PEO770), a transfer of, respectively 57% and 19%, is obtained. We attribute this reduced mass transfer to a competition for the PS surface between the PEO block and the PS block. Atomic force microscopy shows that after transfer the material is evenly spread over the surface. However, upon a short heating of these transferred layers (95 degrees C, 5 min) a dewetting of the PS-PEO layer takes place. These results have a significant impact on the interpretation of the results in a number of papers in which the above-described transfer method was used to produce PEO polymer brushes, in a few cases in combination with heating. We briefly review these papers and discuss their main results in light of this new information. Furthermore, we show that, by using Langmuir-Schaeffer (LS, horizontal) dipping, much higher mass transfers can be reached than with the LB method. When the LB or LS methods are carefully applied, it is a very powerful technique to produce PEO brushes, as it gives full control over both the grafting density and the chain length.

  9. Non-woven nanofiber chitosan/peo membranes obtained by electrospinning

    Directory of Open Access Journals (Sweden)

    M. T. M. Bizarria

    2014-03-01

    Full Text Available The present work focused on the preparation and morphological characterization of chitosan-based nanofiber membranes, aiming at applications in medical and pharmacological areas. Membranes with nanofiber diameters ranging from 50 - 300 nm were prepared from polymer solutions through the electrospinning process. To stabilize the process, it was necessary to use poly(ethylene oxide (PEO, which is a biocompatible synthetic polymer. Pure chitosan solutions, as well as chitosan and PEO solution blends, were characterized by their rheological behavior, conductivity, and surface tension measurements. The electrospun fiber thermal characteristics and crystalline structures were investigated through thermogravimetric analysis (TG and differential scanning calorimetry (DSC. Scanning electron microscopy images (SEM were used for the morphological evaluations of the membranes. The addition of PEO to the chitosan solutions improved their electrical conductivity, surface tension and viscosity, greatly favoring the electrospinning process. Thus, membranes with 80% chitosan could be electrospun.

  10. Factors Influencing Plasma Electrolytic Oxidation(PEO) Coatings on Magnesium Alloys: A Review

    Energy Technology Data Exchange (ETDEWEB)

    Shim, Gunchoo [KISTI ReSEAT Program, Daejon (Korea, Republic of)

    2017-05-15

    Magnesium alloys, which possess excellent specific strength and castability, are highly susceptible to corrosion. Although anodizing is widely used to resolve this problem, it requires toxic electrolytes and produces relatively thin and weak surface coatings. Recently, plasma electrolytic oxidation (PEO) has emerged as an alternative to anodizing. Although it is derived from conventional anodizing, it uses eco-friendly electrolytes and forms thicker, denser, and harder coatings on the surface of magnesium alloys. However, PEO is a complex process involving physical, chemical, and electrochemical reactions, and it is influenced by various factors such as the alloy substrate composition, electrolyte/additive composition, and the electrical variables including the mode of power supply, applied voltage/current density, frequency, and duty cycle. In this article, the detailed effects of these parameters on the microstructure and properties of the PEO coatings are reviewed, and methods of improving the coatings are proposed.

  11. The effect of PEO block lengths on the size and stability of complex coacervate core micelles.

    Science.gov (United States)

    Adams, Dave J; Rogers, Sue H; Schuetz, Peter

    2008-06-15

    We report on a series of polyion complexes from mixtures of poly(ethylene oxide)-block-poly(N,N-diethylaminoethylmethacrylate) (PEO-PDEAMA) and poly(ethylene oxide)-block-poly(aspartic acid) (PEO-PAsp). As expected, the micelle size, polydispersity and stability are dependant on the relative and absolute lengths of the polyelectrolyte chains. However, we also demonstrate that whilst the length of the charged polyelectrolyte blocks is important, the length of the PEO chains is an equally relevant variable in determining both the size and stability of the final micelles as well as the degree of charge neutralisation at which micellisation occurs. We also show that the kinetics of formation can result in very different stability of the final micelles.

  12. Integrated antimicrobial and antifouling ultrafiltration membrane by surface grafting PEO and N-chloramine functional groups.

    Science.gov (United States)

    Hou, Shuhua; Xing, Jialin; Dong, Xue; Zheng, Jifu; Li, Shenghai

    2017-08-15

    Ultrafiltration membranes with integrated antimicrobial and antifouling properties were fabricated using an engineering thermoplastic (carboxylated cardopoly(aryl ether ketone, PEK-COOH). Different molecular weights of PEO (Mw: 120, 350, 550) were grafted to the PEK-COOH membrane surface via EDC/NHS methodology. N-chloramine modified membranes then were prepared by simple exposure to dilute sodium hypochlorite solution. The surface grafting processes were all performed in water (i.e. without organic solvent). With this surface modification, the hydrophilicity of membranes improved significantly and the pure water flux increased compared to the unmodified PEK-COOH membrane. Furthermore, the PEO and N-chloramine modified membranes were resistant not only to both protein adsorption and bacterial adhesion, but also to microbial proliferation. The results of this work suggest that PEO and N-chloramine modified membranes are promising as fouling-resistant membranes. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Role of PEO coatings in long-term biodegradation of a Mg alloy

    Science.gov (United States)

    Matykina, E.; Garcia, I.; Arrabal, R.; Mohedano, M.; Mingo, B.; Sancho, J.; Merino, M. C.; Pardo, A.

    2016-12-01

    Long-term effect of plasma electrolytic oxidation (PEO) coatings on in vitro corrosion of 3D Mg implant specimens has been investigated in simulated body fluid (SBF). Hydrogen evolution rate in PEO-coated specimens was 35 times lower compared to the non-coated alloy during first 2 weeks of immersion (0.04-0.07 mL cm-2 d-1) and reached a steady-state rate of 0.3 mL cm-2 d-1 by week 6 of immersion. Studies of the tribocorrosion behaviour of the PEO-coated alloy disclosed that the coatings rapidly lose their tribocorrosion resistance due to hydration of the coating material and associated drastic decrease of microhardness but exhibit a better tirbocorrosion performance than the non-coated material.

  14. Interaction of platelets, fibrinogen and endothelial cells with plasma deposited PEO-like films

    Science.gov (United States)

    Yang, Zhilu; Wang, Jin; Li, Xin; Tu, Qiufen; Sun, Hong; Huang, Nan

    2012-02-01

    For blood-contacting biomedical implants like retrievable vena cava filters, surface-based diagnostic devices or in vivo sensors, limiting thrombosis and cell adhesion is paramount, due to a decrease even failure in performance. Plasma deposited PEO-like films were investigated as surface modifications. In this work, mixed gas composed of tetraethylene glycol dimethyl ether (tetraglyme) vapor and oxygen was used as precursor. It was revealed that plasma polymerization under high ratio of oxygen/tetraglyme led to deposition of the films that had high content of ether groups. This kind of PEO-like films had good stability in phosphate buffer solution. In vitro hemocompatibility and endothelial cell (EC) adhesion revealed low platelet adhesion, platelet activation, fibrinogen adhesion, EC adhesion and proliferation on such plasma deposited PEO-like films. This made it a potential candidate for the applications in anti-fouling surfaces of blood-contacting biomedical devices.

  15. Transferring lithium ions in nanochannels: a PEO/Li⁺ solid polymer electrolyte design.

    Science.gov (United States)

    Yang, Ling-Yun; Wei, Da-Xiu; Xu, Min; Yao, Ye-Feng; Chen, Qun

    2014-04-01

    A new category of crystalline polymer electrolyte prepared by the supramolecular self-assembly of polyethylene oxide (PEO), α-cyclodextrin (α-CD), and LiAsF6 is reported. The polymer electrolyte consists of the nanochannels formed by α-CDs in which the PEO/Li(+) complexes are confined. The nanochannels formed by α-CD provide the pathway for the directional motion of Li(+) ions and at the same time prevent the access of the anions by size exclusion, resulting in good separation of the Li(+) ions and the anions. The conductivity of the reported material is 30 times higher than that of the comparable PEO/Li(+) complex crystal at room temperature. By using state-of-art solid-state NMR spectroscopy, the structure and dynamics of the material were investigated in detail. The dynamics of the Li(+) ions was studied and correlated to the ionic conductivity of the material.

  16. A patient with two mitochondrial DNA mutations causing PEO and LHON.

    Science.gov (United States)

    Melberg, Atle; Moslemi, Ali-Reza; Palm, Oscar; Raininko, Raili; Stålberg, Erik; Oldfors, Anders

    2009-01-01

    We report a 22-year-old man with PEO and optic atrophy. PEO developed before the onset of optic atrophy. The patient showed mitochondrial myopathy with cytochrome c oxidase deficient fibers. In skeletal muscle the patient was homoplasmic for the mtDNA G11778A Leber hereditary optic neuropathy (LHON) mutation and heteroplasmic for the mtDNA 5 kb "common" deletion mutation. In blood only the homoplasmic LHON mutation was identified. The occurrence of two pathogenic mtDNA mutations is exceedingly rare. The clinical findings in this patient indicate that the combination of the two mtDNA mutations resulted in the expected combined phenotype since the mtDNA deletion mutation accounted for the PEO and the mtDNA G11778A point mutation for the optic atrophy.

  17. Electrochemical Performance of Solid Polymer Electrolyte PEO20-LiTf-Urea1.s

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ding; YAN Hui; ZHANG Huan; QI Lu

    2011-01-01

    A new solid polymer electrolyte PEO20-LiTf-Urea1.5 was prepared by solution casting technique. The energy of frontier orbitals for the components of the electrolyte was predicted by quantum chemistry calculations, and TG stability and electrochemical features were measured. Urea exhibited a lower HOMO energy than PEO, implying its enhanced stability against electrochemical oxidation. Experimentally addition of urea increases the ionic conductivity, which guarantees conductivity requirement for lithium ion batteries. It also results in significant improved electrochemical stability with good thermal stability. Favorable lithium stripping/plating performance is yielded, and it confirms the good stability of the solid electrolyte interphase for the PEO20-LiTf-Urea1.5 system.

  18. Synthesis of hyperbranched polypeptide and PEO block copolymer by consecutive thiol-yne chemistry.

    Science.gov (United States)

    Chang, Xiao; Dong, Chang-Ming

    2013-09-09

    Hyperbranched poly(ε-benzyloxycarbonyl-L-lysine) (HPlys) with multiple alkyne peripheries was synthesized through the click polycondensation of an AB2 type Plys macromonomer with α-thiol and ω-alkyne terminal groups (thiol is the A unit, and each π bond in alkyne is the B unit), and the resulting HPlys was further conjugated with thiol-termined poly(ethylene oxide) (PEO) to generate HPlys-b-PEO block copolymer by consecutive thiol-yne chemistry. Their molecular structures and physical properties were characterized in detail by FT-IR, (1)H NMR, gel permeation chromatography, differential scanning calorimetry, wide-angle X-ray diffraction, and polarized optical microscopy. HPlys and HPlys-b-PEO mainly assumed an α-helix conformation similar to the linear precursors, while the liquid crystalline phase transition of Plys segment disappeared within HPlys and HPlys-b-PEO. HPlys-b-PEO self-assembled into nearly spherical micelles in aqueous solution, while it gave a 5-fold lower critical aggregation concentration (8.9 × 10(-3) mg/mL) than a linear counterpart (4.5 × 10(-2) mg/mL), demonstrating a dendritic topology effect. Compared with a linear counterpart, HPlys-b-PEO gave a higher drug-loading capacity and efficiency for the anticancer drug doxorubicin (DOX) and a slower drug-release rate with an improved burst-release profile, enabling them useful for drug delivery systems. Importantly, this work provides a versatile strategy for the synthesis of hyperbranched polypeptides and related block copolymers by utilizing thiol-yne chemistry.

  19. Micellization of symmetric PEP-PEO block copolymers in water molecular weight dependence

    CERN Document Server

    Kaya, H; Allgaier, J; Stellbrink, J; Richter, D

    2002-01-01

    The micellar behaviour of the amphiphilic block copolymer poly-(ethylene-propylene)-poly-(ethylene oxide) (PEP-PEO) in aqueous solution has been studied with small-angle neutron scattering. The polymer was studied over a wide range of molecular weights, always keeping the volume of the blocks equal. The scattering behaviour of the solutions showed that a morphological transition takes place upon lowering the molecular weight. The high molecular weight block copolymers all build spherical, monodisperse micelles with large aggregation numbers. At low molecular weights, however, cylindrical micelles are formed. An interesting intermediate case is represented by the PEP2-PEO2 system, in which a morphological transition occurs upon dilution. (orig.)

  20. A novel mutation (8342G-->A) in the mitochondrial tRNA(Lys) gene associated with progressive external ophthalmoplegia and myoclonus.

    Science.gov (United States)

    Tiranti, V; Carrara, F; Confalonieri, P; Mora, M; Maffei, R M; Lamantea, E; Zeviani, M

    1999-03-01

    We describe a patient who suffered from impaired ocular motility from age 10 years and at 16 years developed ptosis, proximal weakness and progressive fatigability. At 35 years she developed massive myoclonic jerks, and head and distal tremor. A muscle biopsy showed a high percentage of cytochrome c oxidase negative fibers but no ragged-red fibers. A novel heteroplasmic mutation (8342G-->A) was found in the mitochondrial transfer RNA(Lys) gene by single-strand conformation polymorphism screening, followed by sequence and restriction fragment length polymorphism analysis. Approximately 80% of muscle mitochondrial DNA (mtDNA) harbored the mutation, while the mutation was absent in lymphocyte DNA of the proband, as well as of her mother, daughter and a maternal aunt. However, the pathogenicity of the mutation was confirmed by restriction fragment length polymorphism analysis of single muscle fibers, which revealed a significantly greater level of mutant mtDNA in cytochrome c oxidase negative over cytochrome c oxidase positive fibers.

  1. Amphiphilic PEO-b-PBLG diblock and PBLG-b-PEO-b-PBLG triblock copolymer based nanoparticles: doxorubicin loading and in vitro evaluation.

    Science.gov (United States)

    Kakkar, Dipti; Mazzaferro, Silvia; Thevenot, Julie; Schatz, Christophe; Bhatt, Anant; Dwarakanath, Bilikere S; Singh, Harpal; Mishra, Anil K; Lecommandoux, Sebastien

    2015-01-01

    Huisgen's 1,3-dipolar cycloaddition ("Click Chemestry") has been used to prepare amphiphilic PEO-b-PBLG diblock and PBLG-b-PEO-b-PBLG triblock copolymers as potential carriers of anticancer drugs. Spherical and flower shaped micelles (D ≈ 100 nm) were obtained from diblock and triblock copolymers respectively. DOX was effectively encapsulated up to 18 wt.% and 50-60% of it was steadily released from the micelles over a period of 7 d. Flow cytometry and fluorescence microscopy confirmed the effective intracellular uptake as well as the sustained release of DOX from micelles. These results suggest that the diblock as well as triblock copolymers are promising carriers for intra-cellular drug delivery.

  2. Effect of chain length of PEO on the gelation and micellization of the pluronic F127 copolymer aqueous system.

    Science.gov (United States)

    Pragatheeswaran, Abhinav Maheswaran; Chen, Shing Bor

    2013-08-06

    The effect of adding homopolymer poly(ethylene oxide) (PEO) on the sol/gel behavior of amphiphilic triblock copolymer Pluronic F127 ((EO)98(PO)67(EO)98) in aqueous media is explored. Emphasis is placed on the influence of the PEO molecular weight and concentration on micellization and gelation and the exploration of their correlation. PEO is always found to lower the critical micellization temperature modestly. However, short PEO chains promote the gelation of F127, and long chains delay or even curb gel formation. Micelle size measurements and cryo-TEM micrographs provide evidence for micellar aggregation via the bridging of long PEO chains or depletion flocculation, thereby impeding the ordering of micelles for gel formation.

  3. Structure Formation of Ultrathin PEO Films at Solid Interfaces—Complex Pattern Formation by Dewetting and Crystallization

    Directory of Open Access Journals (Sweden)

    Hans-Georg Braun

    2013-02-01

    Full Text Available The direct contact of ultrathin polymer films with a solid substrate may result in thin film rupture caused by dewetting. With crystallisable polymers such as polyethyleneoxide (PEO, molecular self-assembly into partial ordered lamella structures is studied as an additional source of pattern formation. Morphological features in ultrathin PEO films (thickness < 10 nm result from an interplay between dewetting patterns and diffusion limited growth pattern of ordered lamella growing within the dewetting areas. Besides structure formation of hydrophilic PEO molecules, n-alkylterminated (hydrophobic PEO oligomers are investigated with respect to self-organization in ultrathin films. Morphological features characteristic for pure PEO are not changed by the presence of the n-alkylgroups.

  4. Effects of Bile Salt Sodium Glycodeoxycholate on the Self-Assembly of PEO-PPO-PEO Triblock Copolymer P123 in Aqueous Solution.

    Science.gov (United States)

    Bayati, Solmaz; Galantini, Luciano; Knudsen, Kenneth D; Schillén, Karin

    2015-12-22

    A comprehensive experimental study on the interaction between the PEO-PPO-PEO block copolymer P123 (EO20PO68EO20) and the anionic bile salt sodium glycodeoxycholate (NaGDC) in water has been performed. The work was aimed at investigating the suitability of using P123 as bile salt sequestrant beside the fundamental aspects of PEO-PPO-PEO block copolymer-bile salt interactions. Various experimental techniques including dynamic and static light scattering, small-angle X-ray scattering, and differential scanning calorimetry (DSC) were employed in combination with electrophoretic mobility measurements. The system was investigated at a constant P123 concentration of 1.74 mM and with varying bile salt concentrations up to approximately 250 mM NaGDC (or a molar ratio n(NaGDC)/n(P123) = 144). In the mixed P123-NaGDC solutions, the endothermic process related to the self-assembly of P123 was observed to gradually decrease in enthalpy and shift to higher temperatures upon progressive addition of NaGDC. To explain this effect, the formation of NaGDC micelles carrying partly dehydrated P123 unimers was proposed and translated into a stoichiometric model, which was able to fit the experimental DSC data. In the mixtures at low molar ratios, NaGDC monomers associated with the P123 micelle forming a charged "P123 micelle-NaGDC" complex with a dehydrated PPO core. These complexes disintegrated upon increasing NaGDC concentration to form small "NaGDC-P123" complexes visualized as bile salt micelles including one or a few P123 copolymer chains.

  5. Nature of interactions between PEO-PPO-PEO triblock copolymers and lipid membranes: (I) effect of polymer hydrophobicity on its ability to protect liposomes from peroxidation.

    Science.gov (United States)

    Wang, Jia-Yu; Marks, Jeremy; Lee, Ka Yee C

    2012-09-10

    PEO-PPO-PEO triblock copolymers have opposing effects on lipid membrane integrity: they can behave either as membrane sealants or as membrane permeabilizers. To gain insights into their biomembrane activities, the fundamental interactions between a series of PEO-based polymers and phospholipid vesicles were investigated. Specifically, the effect of copolymer hydrophobicity on its ability to prevent liposomes from peroxidation was evaluated, and partitioning free energy and coefficient involved in the interactions were derived. Our results show that the high degree of hydrophilicity is a key feature of the copolymers that can effectively protect liposomes from peroxidation and the protective effect of the copolymers stems from their adsorption at the membrane surface without penetrating into the bilayer core. The origin of this protective effect induced by polymer absorption is attributed to the retardation of membrane hydration dynamics, which is further illustrated in the accompanying study on dynamic nuclear polarization (DNP)-derived hydration dynamics (Cheng, C.-Y.; Wang, J.-Y.; Kausik, R.; Lee, K. Y. C.; Han S. Biomacromolecules, 2012, DOI: 10.1021/bm300848c).

  6. In vitro degradation, hemolysis, and cytocompatibility of PEO/PLLA composite coating on biodegradable AZ31 alloy.

    Science.gov (United States)

    Wei, Zhongling; Tian, Peng; Liu, Xuanyong; Zhou, Bangxin

    2015-02-01

    Magnesium and its alloys have large potential as degradable and absorbable biomaterials because of their mechanical properties and biocompatibility. However, their corrosion resistance is usually inadequate especially in physiological environment, which limits their broad applications in biomedical areas. In this work, plasma electrolytic oxidized/poly(l-lactide) (PEO/PLLA) composite coating was successfully fabricated on biodegradable AZ31 alloy by combing PEO process and sealing with PLLA. The microstructure, elemental composition, and phase composition of the PEO/PLLA composite coating were investigated. The in vitro degradation of the PEO/PLLA composite coating in simulated body fluid (SBF) was also systematically evaluated. The results revealed that the PEO/PLLA composite coating improved the corrosion resistance of AZ31 alloy significantly. The corrosion potential shifted from -1.663V to more positive position -1.317 V and the corrosion current density was reduced with six-order of magnitude. The Mg(2+) ions, hydrogen release, and pH value change of solution caused by degradation were all decreased significantly. Moreover, the PEO process played a critical role in sustaining the integrity of the implant in long-term service. The result of hemolysis test showed that the PEO/PLLA composite coating vested AZ31 alloy a low hemolysis ratio (0.806 ± 0.771)%, which is much lower than the safe value of 5% according to ISO 10993-4. For the cytocompatibility test, compared with bare AZ31 alloy and PEO coating, MC3T3-E1 cells showed much better adhesion and proliferation on the PEO/PLLA composite coating with nearly 4-fold increase of cells after 7-day cultivation, indicating that the PEO/PLLA composite coating has good biocompatibility for biomedical applications.

  7. Preparation and Characterization of PEO-LATP/LAGP Ceramic Composite Electrolyte Membrane for Lithium Batteries%锂离子电池PEO-LATP/LAGP陶瓷复合电解质膜的制备与性能表征

    Institute of Scientific and Technical Information of China (English)

    黄乐之; 温兆银; 靳俊; 刘宇

    2012-01-01

    设计并制备了PEO-LATP/LAGP陶瓷复合电解质.使用NASICON结构的Li1.4Al0.4Ti1.6(PO4)3 (LATP)或Li1.5Al0.5Ge1.5(PO4)3 (LAGP)作为陶瓷基体,以PEO为粘结剂,得到了均匀、厚度仅为20 μm的复合电解质膜.通过电化学性能表征发现当w(LATP/LAGP)∶w(PEO)=7∶3时,复合电解质膜具有最高的室温电导率,达到0.186 mS/cm(PEO-LATP)与0.111 mS/cm (PEO-LAGP).通过充放电循环实验表明,Li/复合电解质/LiCo1/3Ni1/3Mn1/3O2电池的首次放电容量达170 mAh/g.使用PEO-LATP复合电解质的电池在循环时有较大的容量衰减,而使用PEO-LAGP复合电解质则循环性能有明显的改善,在10次循环后仍保持在150 mAh/g.%A PEO-LATP/LAGP composite electrolyte for lithium batteries was designed and prepared. Uniformly composite electrolyte membrane with thickness of 20 μm was obtained by assembling Li1.4Al0.4Ti1.6(PO4)3 (LATP) or Li1.5Al0.5Ge1.5(PO4)3 (LAGP) as ceramic substrate and PEO as binder. Highest room-temperature conductivities were achieved for the sample prepared with w(ceramics):w(PEO)=7:3. Electrochemical analysis showed that the conductivity reached 0.186 mS/cm for PEO-LATP and 0.111 mS/cm for PEO-LAGP. Cycling performances of 170 mAh/g was obtained for the first discharge capacity of the Li/composite electrolyte/LiCo1/3Ni1/3Mn1/3O2 cell. Sharp decrease of cycling capacity was observed for the cell using PEO-LATP membrane. The cycling performance of the PEO-LAGP based cell was greatly improved with 150 mAh/g remained after 10 cycles.

  8. Investigation of electrode distance impact on PEO coating formation assisted by simulation

    Science.gov (United States)

    Ma, Xun; Blawert, Carsten; Höche, Daniel; Zheludkevich, Mikhail L.; Kainer, Karl U.

    2016-12-01

    The influence of electrode distance between anode and cathode during plasma electrolytic oxidation (PEO) process on the coating formation was investigated by combining experiments and simulation. Firstly a model was built to simulate the effect of electrode distance on the anodic current distribution using finite element analyses. Complementary, PEO coatings were fabricated on AM50 magnesium alloy in an alkaline electrolyte with different electrode distances applying constant voltage. Phase composition, coating morphology and thickness were studied for both the front and back sides of the PEO coating depending on the electrode distance. For paralleled plate-like electrodes, based on coating uniformity, an optimum electrode distance of 60-80 mm was identified under the chosen experimental conditions. Via correlation of simulation and experimental results, the influence of electrode distance on coating formation is explored. It is demonstrated that under constant voltage mode, PEO coating formation is affected by electrode distance on both front and back sides of magnesium substrates. This effect is ascribed to the influence of electrode distance on the current distribution in the bath and to the related average current density on the surfaces.

  9. Nuclear magnetic resonance study of PEO-chitosan based polymer electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Donoso, J.P.; Lopes, L.V.S. [IFSC, Universidade de Sao Paulo, PO Box 369, 13560-970 Sao Carlos-SP (Brazil); Pawlicka, A. [IQSC, Universidade de Sao Paulo, PO Box 780, 13560-970 Sao Carlos-SP (Brazil); Fuentes, S. [Department of Physics, Faculty of Sciences, Universidad Catolica del Norte, Angamos 0610, Antofagasta (Chile); Retuert, P.J. [Department of Material Sciences, Faculty of Mathematical and Physical Sciences, Universidad de Chile, Tupper 2069, Santiago (Chile); Gonzalez, G. [Department of Chemistry, Faculty of Sciences, Universidad de Chile, Casilla 653, Santiago (Chile)

    2007-12-31

    This work investigates lithium dynamics in a series of polymer electrolytes formed by poly(ethylene oxide) PEO, chitosan (QO), amino propil siloxane (pAPS) and lithium perchlorate by means of nuclear magnetic resonance techniques. Lithium ({sup 7}Li) lineshapes and spin-lattice relaxation times were measured as a function of temperature. The results suggest that the chemical functionality of QO, particularly the amine group, participate in coordinating lithium ion in the composites. The competition between QO and PEO for lithium ions is evident in the binary system. In the ternary electrolyte containing PEO, QO and pAPS, it is observed that the lithium ions can competitively interact with the two polymers. The heterogeneity, at a local microscopic scale, is revealed by a temperature-dependent equilibrium of lithium ion concentration between at least two different microphases; on 37dominated by the interactions with chitosan and the other one with polyether. The data of the ternary electrolyte was analysed by assuming two lithium dynamics, the first one associated to the motion of the lithium ion dissolved in PEO and the second one associated to those complexed by the chitosan. (author)

  10. PEO of pre-anodized Al–Si alloys: Corrosion properties and influence of sealings

    Energy Technology Data Exchange (ETDEWEB)

    Mohedano, M., E-mail: marta.mohedano@hzg.de [Helmholtz Zentrum Geesthacht, Magnesium Innovation Centre, Institute of Materials Research, Max-Planck-Str. 1, D-21502 Geesthacht (Germany); Matykina, E.; Arrabal, R.; Mingo, B.; Pardo, A. [Departamento de Ciencia de Materiales, Facultad de Ciencias Químicas, Universidad Complutense, 28040 Madrid (Spain)

    2015-08-15

    Highlights: • A356 gravity-cast and rheocast pre-anodized aluminium alloys were coated by PEO. • Different sealing techniques were applied after the coating process. • Iron-rich constituents of the substrate occlude the continuity of the porous anodic film. • PEO coatings consisted of a mixture of α-Al{sub 2}O{sub 3}, γ-Al{sub 2}O{sub 3} and mullite. • Post-treatments improved both hydrophobic and corrosion properties. - Abstract: Voltage-controlled PEO coatings were developed on A356 aluminum alloys (gravity-cast and rheocast) with a pre-anodized layer. The influence of the alloy manufacturing process and the effect of Si-rich phase on the structure and composition of the oxide layers were evaluated using SEM, EDS and XRD. The pre-anodized oxide layer preserves the microstructure of the substrate due to the presence of secondary phases that have a different behavior relative to the matrix during anodizing. PEO coatings consisted of a mixture of α-Al{sub 2}O{sub 3}, γ-Al{sub 2}O{sub 3} and mullite. The corrosion behavior and the effectiveness of different sealing techniques based on salts of nickel, cobalt, cerium and phosphonic acid were also studied. Post-treatments improved the hydrophobic properties of the coatings and showed a beneficial effect, significantly increasing the coating impedance and thereby reducing the susceptibility to corrosion.

  11. Structure and dynamics of water in mixed solutions including laponite and PEO

    Science.gov (United States)

    Morikubo, Satoshi; Sekine, Yurina; Ikeda-Fukazawa, Tomoko

    2011-01-01

    To investigate the structure and dynamics of water in mixed solutions including laponite clay particles and poly(ethylene oxide) (PEO), we measured the Raman spectra of the mixed solutions in the temperature range 283-313 K. The results show that the vibrational energies of the O-H stretching modes in the mixed solutions depend on the water content and temperature. The energy shifts of the O-H stretching modes are attributed to changes in the water structure. By applying a structural model of bulk water to the spectra in the O-H stretching region, the local structures of water in the solutions were analyzed. The result shows that the formation probability of hydrogen bonds in the solutions decreases as the water content decreases. Laponite and PEO have effects to disrupt the network structure of hydrogen bonds between water molecules. Further, it was found that laponite and PEO cause increase in the strength of hydrogen bonds of surrounding water,although the strength of the hydrogen bonds increases with the order water-laponite laponite-PEO mixed solutions has a less-networked structure with strong hydrogen bonds compared with bulk water.

  12. Gas plasma etching of PEO/PBT segmented block copolymer films

    NARCIS (Netherlands)

    Olde riekerink, M.B.; Claase, M.B.; Engbers, G.H.M.; Grijpma, Dirk W.; Feijen, Jan

    2003-01-01

    A series of poly(ethylene oxide)/poly(butylene terephthalate) (PEO/PBT) segmented block copolymer films was treated with a radio-frequency carbon dioxide (CO2) or with argon (Ar) plasma. The effects of (preferential) etching on surface structure, topography, chemistry, and wettability were studied

  13. Gas plasma etching of PEO/PBT segmented block copolymer films.

    Science.gov (United States)

    Olde Riekerink, M B; Claase, M B; Engbers, G H M; Grijpma, D W; Feijen, J

    2003-06-15

    A series of poly(ethylene oxide)/poly(butylene terephthalate) (PEO/PBT) segmented block copolymer films was treated with a radio-frequency carbon dioxide (CO(2)) or with argon (Ar) plasma. The effects of (preferential) etching on surface structure, topography, chemistry, and wettability were studied by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and contact angle measurements. In all cases, a granular-type nanostructure was formed after prolonged CO(2) plasma etching. Ar plasma etching generally did not lead to significant changes in surface structure. Regarding surface chemistry, CO(2) plasma treatment caused surface oxidation and oxidative degradation of the films while Ar plasma etching resulted mainly in the preferential removal of PEO blocks. The wettability of all films significantly increased after plasma treatment because of the creation of polar functional groups at the surface. Preliminary goat bone-marrow cell compatibility experiments have shown that all plasma-treated PEO/PBT films induced a greatly enhanced cell adhesion and/or growth compared to untreated biomaterials. This improvement was attributed to changes in surface chemistry during plasma etching rather than to changes in surface structure. These results show that plasma-treated PEO/PBT copolymers have a high potential as scaffolds for bone tissue regeneration. Copyright 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 417-428, 2003

  14. Controlled release of doxorubicin from electrospun PEO/chitosan/graphene oxide nanocomposite nanofibrous scaffolds.

    Science.gov (United States)

    Ardeshirzadeh, Behnaz; Anaraki, Nadia Aboutalebi; Irani, Mohammad; Rad, Leila Roshanfekr; Shamshiri, Soodeh

    2015-03-01

    Polyethylene oxide (PEO)/chitosan (CS)/graphene oxide (GO) electrospun nanofibrous scaffolds were successfully developed via electrospinning process for controlled release of doxorubicin (DOX). The SEM analysis of nanofibrous scaffolds with different contents of GO (0.1, 0.2, 0.5 and 0.7wt.%) indicated that the minimum diameter of nanofibers was found to be 85nm for PEO/CS/GO 0.5% nanofibers. The π-π stacking interaction between DOX and GO with fine pores of nanofibrous scaffolds exhibited higher drug loading (98%) and controlled release of the DOX loaded PEO/CS/GO nanofibers. The results of DOX release from nanofibrous scaffolds at pH5.3 and 7.4 indicated strong pH dependence. The hydrogen bonding interaction between GO and DOX could be unstable under acidic conditions which resulted in faster drug release rate in pH5.3. The cell viability results indicated that DOX loaded PEO/CS/GO/DOX nanofibrous scaffold could be used as an alternative source of DOX compared with free DOX to avoid the side effects of free DOX. Thus, the prepared nanofibrous scaffold offers as a novel formulation for treatment of lung cancer.

  15. Laminin-modified and aligned PHBV/PEO nanofibrous nerve conduits promote peripheral nerve regeneration.

    Science.gov (United States)

    Zhang, Xiao-Feng; Liu, Hai-Xia; Ortiz, Lazarus Santiago; Xiao, Zhong-Dang; Huang, Ning-Ping

    2016-11-12

    Poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) has received much attention for its biodegradability and biocompatibility, characteristics which are required in tissue engineering. In this study, polyethylene oxide (PEO)-incorporated PHBV nanofibers with random or aligned orientation were obtained by electrospinning. For further use in vivo, the nanofiber films were made into nerve conduits after treated with NH3 plasma, which could improve the hydrophilicity of inner surfaces of nerve conduits and then facilitate laminin adsorption via electrostatic interaction for promoting cell adhesion and proliferation. Morphology of the surfaces of modified PHBV/PEO nanofibrous scaffolds were examined by scanning electron microscopy. Schwann cell viability assay was conducted and the results confirmed that the functionalized nanofibers were favorable for cell growth. Morphology of Schwann cells cultured on scaffolds showed that aligned nanofibrous scaffolds provided topographical guidance for cell orientation and elongation. Furthermore, 3D PHBV/PEO nerve conduits made from aligned and random-oriented nanofibers were implanted into 12-mm transected sciatic nerve rat model and subsequent analysis were conducted at 1 and 2 months post-surgery. The above functionalized PHBV/PEO scaffolds provide a novel and promising platform for peripheral nerve regeneration.

  16. Emulsions stabilized with PEO–PPO–PEO block copolymers and silica

    NARCIS (Netherlands)

    Gosa, Kristiana-Lisette; Uricanu, Violeta

    2002-01-01

    The specific behavior of poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (PEO–PPO–PEO) tri-block copolymers in aqueous solutions was studied in the presence of vinyl acetate (VAc) and colloidal silica. Several factors controlling specific interactions were investigated, the block cop

  17. Protein adsorption can be reversibly switched on and off on mixed PEO/PAA brushes.

    Science.gov (United States)

    Delcroix, M F; Laurent, S; Huet, G L; Dupont-Gillain, C C

    2015-01-01

    Adsorption of proteins on surfaces placed in biological fluids is a ubiquitous and mostly irreversible phenomenon, desirable or not, but often uncontrolled. Adsorption of most proteins on poly(ethylene oxide) (PEO) brushes is very limited, while the amount of proteins adsorbed on poly(acrylic acid) (PAA) brushes varies with the pH and ionic strength (I) of the protein solution. Mixed brushes of PEO and PAA are designed here to reversibly adsorb and desorb albumin, lysozyme, collagen and immunoglobulin G, four very different proteins in terms of size, solubility and isoelectric point. Protein adsorption and desorption are monitored using X-ray photoelectron spectroscopy, as well as with quartz crystal microbalance for in situ and real-time measurements. Large amounts of protein are adsorbed and then nearly completely desorbed on mixed PEO/PAA brushes by a simple pH and I trigger. The mixed brushes thus nicely combine the properties of pure PAA and pure PEO brushes. These adsorption/desorption cycles are shown to be repeated with high efficiency. The high-performance smart substrates created here could find applications in domains as diverse as biosensors, drug delivery and nanotransport.

  18. The evaluation of physical properties of injection molded systems based on poly(ethylene oxide) (PEO).

    Science.gov (United States)

    Pajander, Jari; Rensonnet, Alexia; Hietala, Sami; Rantanen, Jukka; Baldursdottir, Stefania

    2017-02-25

    The effect of product design parameters on the formation and properties of an injection molded solid dosage form consisting of poly(ethylene oxide)s (PEO) and two different active pharmaceutical ingredients (APIs) was studied. The product design parameters explored were melting temperature and the duration of melting, API loading degree and the molecular weight (Mw) of PEO. The solid form composition of the model APIs, theophylline and carbamazepine, was of specific interest, and its possible impact on the in vitro drug release behavior. Mw of PEO had the greatest impact on the release rate of both APIs. High Mw resulted in slower API release rate. Process temperature had two-fold effect with PEO 300,000g/mol. Firstly, higher process temperature transformed the crystalline part of the polymer into metastable folded form (more folded crystalline regions) and less into the more stable extended form (more extended crystalline regions), which lead to enhanced theophylline release rate. Secondly, the higher process temperature seemed to induce carbamazepine polymorphic transformation from p-monoclinic form III (carbamazepine (M)) into trigonal form II (carbamazepine (T)). The results indicated that the actual content of carbamazepine (T) affected drug release behavior more than the magnitude of transformation.

  19. Hybrid titanium dioxide/PS-b-PEO block copolymer nanocomposites based on sol-gel synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez, J; Tercjak, A; Garcia, I; Peponi, L; Mondragon, I [' Materials-Technologies' Group, Departamento Ingenieria Quimica y Medio Ambiente, Escuela Politecnica, Universidad PaIs Vasco/Euskal Herriko Unibertsitatea, Plaza Europa 1, E-20018 Donostia-San Sebastian (Spain)], E-mail: inaki.mondragon@ehu.es

    2008-04-16

    The poly(styrene)-b-poly(ethylene oxide) (SEO) amphiphilic block copolymer, with two different molecular weights, has been used as a structure directing agent for generating nanocomposites of TiO{sub 2}/SEO via the sol-gel process. SEO amphiphilic block copolymers are designed with a hydrophilic PEO-block which can interact with inorganic molecules, as well as a hydrophobic PS-block which builds the matrix. The addition of different amounts of sol-gel provokes strong variations in the self-assembled morphology of TiO{sub 2}/SEO nanocomposites with respect to the neat block copolymer. As confirmed by atomic force microscopy (AFM), TiO{sub 2}/PEO-block micelles get closer, forming well-ordered spherical domains, in which TiO{sub 2} nanoparticles constitute the core surrounded by a corona of PEO-blocks. Moreover, for 20 vol% sol-gel the generated morphology changes to a hexagonally ordered structure for both block copolymers. The cylindrical structure of these nanocomposites has been confirmed by the two-dimensional Fourier transform power spectrum of the corresponding AFM height images. Affinity between titanium dioxide precursor and PEO-block of SEO allows us to generate hybrid inorganic/organic nanocomposites, which retain the optical properties of TiO{sub 2}, as evaluated by UV-vis spectroscopy.

  20. Ionic Conductance, Thermal and Morphological Behavior of PEO-Graphene Oxide-Salts Composites

    Directory of Open Access Journals (Sweden)

    Mohammad Saleem Khan

    2015-01-01

    Full Text Available Thin films composites of poly(ethylene oxide-graphene oxide were fabricated with and without lithium salts by solvent cast method. The ionic conductivity of these composites was studied at various concentrations of salt polymer-GO complexes and at different temperatures. The effects of temperature and graphene oxide concentration were measured from Arrhenius conductance plots. It is shown that the addition of salts in pure PEO increases conductance many times. The graphene oxide addition has enhanced the conductance approximately 1000 times as compared to that of pure PEO. The activation energies were determined for all the systems which gave higher values for pure PEO and the value decreased with the addition of LiClO4 and LiCl salts and further decreases with the addition of graphene oxide. The composite has also lowered the activation energy values which mean that incorporation of GO in PEO has decreased crystallinity and the amorphous region has increased the local mobility of polymer chains resulting in lower activation energies. SEM analysis shows uniform distribution of GO in polymer matrix. The thermal stability studies reveal that incorporation of GO has somewhat enhanced the thermal stability of the films.

  1. Cell adhesion to plasma electrolytic oxidation (PEO) titania coatings, assessed using a centrifuging technique.

    Science.gov (United States)

    Robinson, H J; Markaki, A E; Collier, C A; Clyne, T W

    2011-11-01

    The adhesion of bovine chondrocytes and human osteoblasts to three titania-based coatings, formed by plasma electrolytic oxidation (PEO), was compared to that on uncoated Ti-6Al-4V substrates, and some comparisons were also made with plasma sprayed hydroxyapatite (HA) coatings. This was done using a centrifuge, with accelerations of up to 160,000 g, so as to induce buoyancy forces that created normal or shear stresses at the interface. It is shown that, on all surfaces, it was easier to remove cells under normal loading than under shear loading. Cell adhesion to the PEO coatings was stronger than that on Ti-6Al-4V and similar to that on HA. Cell proliferation rates were relatively high on one of the PEO coatings, which was virtually free of aluminium, but low on the other two, which contained significant levels of aluminium. It is concluded that the Al-free PEO coating offers promise for application to prosthetic implants.

  2. Phase diagram of polymer electrolyte: (x(PEO - ( 1-xCF3COOLi

    Directory of Open Access Journals (Sweden)

    Miguel Iban Delgado

    2012-01-01

    Full Text Available A partir de poli(oxido de etileno y trifluoro acetato litio (CF3COOLi, se prepararon electrolitos sólidos poliméricos por el método de solución, para diferentes concentraciones de sal. Las membranas resultantes de la evaporación lenta, se analizaron por calorimetría diferencial de barrido (DSC y se realizó un diagrama de fases a partir de los segundos calentamientos. Las curvas de DSC para un primer barrido muestran tres anomalías a 303, 308 y 393 K, las que cambian lentamente con el contenido de sal. Para altas concentraciones, la intensidad del pico endotérmico asociado con el punto de fusión del PEO (338K decrece, mientras que para la tercera anomalía (asociada a la fusión del complejo PEO:sal la intensidad aumenta. La segunda anomalía desaparece por completo, cuando la concentración de sal alcanza un valor de X = 0,405 (dada en fracción de masa: sal/(sal + PEO. Estos resultados junto alta conductividad del sistema, muestran la formación de un nuevo complejo entre el PEO y la sal.

  3. Ultraporous interweaving electrospun microfibers from PCL-PEO binary blends and their inflammatory responses

    Science.gov (United States)

    Li, Yan-Fang; Rubert, Marina; Aslan, Hüsnü; Yu, Ying; Howard, Kenneth A.; Dong, Mingdong; Besenbacher, Flemming; Chen, Menglin

    2014-02-01

    Production of one dimensional nanomaterials with secondary morphology exhibiting unique functions is challenging. Here we report for the first time that a nanoscale immiscible polymer blend solution electrojet can assemble into ultraporous interweaving microfibers. This intriguingly novel morphology originated from a blend of polycaprolactone (PCL) and polyethylene oxide (PEO) in a DCM-DMF mixed solution when the ratio between each component reached a threshold and when the electrospinning parameters were delicately controlled. The morphology, crystallinity, surface chemistry and wettabilities were characterized to understand the mechanism of formation. The interplay of the two semi-crystalline polymers and the pair of solvents/non-solvents with the electrospinning processing parameters was found to be critical for the formation of the unique structure. Furthermore, the interesting combination of biocompatible, biodegradable PCL with protein-resistant PEO motivated us to assess its inflammation responses on the RAW 264.7 macrophage cell line. All fibers were found to be biocompatible with low inflammation potential upon incubation, while compared with pure PCL nanofibers; the unique interweaving microfibers induced a slightly higher inflammatory reaction.Production of one dimensional nanomaterials with secondary morphology exhibiting unique functions is challenging. Here we report for the first time that a nanoscale immiscible polymer blend solution electrojet can assemble into ultraporous interweaving microfibers. This intriguingly novel morphology originated from a blend of polycaprolactone (PCL) and polyethylene oxide (PEO) in a DCM-DMF mixed solution when the ratio between each component reached a threshold and when the electrospinning parameters were delicately controlled. The morphology, crystallinity, surface chemistry and wettabilities were characterized to understand the mechanism of formation. The interplay of the two semi-crystalline polymers and the

  4. Sequential crystallization and morphology of triple crystalline biodegradable PEO-b-PCL-b-PLLA triblock terpolymers

    KAUST Repository

    Palacios, Jordana

    2016-01-05

    The sequential crystallization of poly(ethylene oxide)-b-poly(e-caprolactone)-b-poly(L-lactide) (PEO-b-PCL-b-PLLA) triblock terpolymers, in which the three blocks are able to crystallize separately and sequentially from the melt, is presented. Two terpolymers with identical PEO and PCL block lengths and two different PLLA block lengths were prepared, thus the effect of increasing PLLA content on the crystallization behavior and morphology was evaluated. Wide angle X-Ray scattering (WAXS) experiments performed on cooling from the melt confirmed the triple crystalline nature of these terpolymers and revealed that they crystallize in sequence: the PLLA block crystallizes first, then the PCL block, and finally the PEO block. Differential scanning calorimetry (DSC) analysis further demonstrated that the three blocks can crystallize from the melt when a low cooling rate is employed. The crystallization process takes place from a homogenous melt as indicated by small angle X-Ray scattering (SAXS) experiments. The crystallization and melting enthalpies and temperatures of both PEO and PCL blocks decrease as PLLA content in the terpolymer increases. Polarized light optical microscopy (PLOM) demonstrated that the PLLA block templates the morphology of the terpolymer, as it forms spherulites upon cooling from the melt. The subsequent crystallization of PCL and PEO blocks occurs inside the interlamellar regions of the previously formed PLLA block spherulites. In this way, unique triple crystalline mixed spherulitic superstructures have been observed for the first time. As the PLLA content in the terpolymer is reduced the superstructural morphology changes from spherulites to a more axialitic-like structure.

  5. Immunotoxicity and genotoxicity testing of PLGA-PEO nanoparticles in human blood cell model.

    Science.gov (United States)

    Tulinska, Jana; Kazimirova, Alena; Kuricova, Miroslava; Barancokova, Magdalena; Liskova, Aurelia; Neubauerova, Eva; Drlickova, Martina; Ciampor, Fedor; Vavra, Ivo; Bilanicova, Dagmar; Pojana, Giulio; Staruchova, Marta; Horvathova, Mira; Jahnova, Eva; Volkovova, Katarina; Bartusova, Maria; Cagalinec, Michal; Dusinska, Maria

    2015-05-01

    A human blood cell model for immunotoxicity and genotoxicity testing was used to measure the response to polylactic-co-glycolic acid (PLGA-PEO) nanoparticle (NP) (0.12, 3, 15 and 75 μg/cm(2) exposure in fresh peripheral whole blood cultures/isolated peripheral blood mononuclear cell cultures from human volunteers (n = 9-13). PLGA-PEO NPs were not toxic up to dose 3 μg/cm(2); dose of 75 μg/cm(2) displays significant decrease in [(3)H]-thymidine incorporation into DNA of proliferating cells after 4 h (70% of control) and 48 h (84%) exposure to NPs. In non-cytotoxic concentrations, in vitro assessment of the immunotoxic effects displayed moderate but significant suppression of proliferative activity of T-lymphocytes and T-dependent B-cell response in cultures stimulated with PWM > CON A, and no changes in PHA cultures. Decrease in proliferative function was the most significant in T-cells stimulated with CD3 antigen (up to 84%). Cytotoxicity of natural killer cells was suppressed moderately (92%) but significantly in middle-dosed cultures (4 h exposure). On the other hand, in low PLGA-PEO NPs dosed cultures, significant stimulation of phagocytic activity of granulocytes (119%) > monocytes (117%) and respiratory burst of phagocytes (122%) was recorded. Genotoxicity assessment revealed no increase in the number of micronucleated binucleated cells and no induction of SBs or oxidised DNA bases in PLGA-PEO-treated cells. To conclude on immuno- and genotoxicity of PLGA-PEO NPs, more experiments with various particle size, charge and composition need to be done.

  6. Morphology and conductivity of in-situ PEO-LiClO4-TiO2 composite polymer electrolyte

    Institute of Scientific and Technical Information of China (English)

    PAN Chun-yue; FENG Qing; WANG Li-jun; ZHANG Qian; CHAO Meng

    2007-01-01

    PEO-LiClO4-TiO2 composite polymer electrolyte films were prepared. TiO2 was formed directly in matrix by hydrolysis and condensation reaction of tetrabutyl titanate. The crystallinity, morphology and ionic conductivity of composite polymer electrolyte films were examined by differential scanning calorimetry, scanning electron microscopy, atom force microscopy and alternating current impedance spectroscopy, respectively. The glass transition temperature and the crystallinity of composite polymer electrolytes are decreased compared with those of PEO-LiClO4 polymer electrolyte film. The results show that TiO2 particles are uniformly dispersed in PEO-LiClO4-5%TiO2 composite polymer electrolyte film. The maximal conductivity of 5.5×10-5 S/cm at 20 ℃ of PEO-LiClO4-TiO2 film is obtained at 5% mass fraction of TiO2.

  7. SYNTHESIS, CHARACTERIZATION AND ION TRANSPORT PROPERTIES OF HOT-PRESSED SOLID POLYMER ELECTROLYTES (1-x) PEO:x KI

    Institute of Scientific and Technical Information of China (English)

    Angesh Chandra; Archana Chandra; K.Thakur

    2013-01-01

    Synthesis and ion transport properties of hot-pressed solid polymer electrolytes (SPEs),(1-x) PEO:x KI,where x is the content of KI in wt%,are reported.A hot-press technique has been used for the formation of the polymeric membranes in place of the usual solution cast method.The composition (80 PEO:20 KI) was identified as the highest conducting polymer electrolyte on the basis of compositional dependent conductivity studies of PEO:KI films.A conductivity enhancement of more than two orders of magnitude from that of the pure PEO was achieved.Materials characterization and ion transport mechanism were explained by using various experimental techniques.

  8. An Epichlorohydrin-Crosslinked Semi-Interpenetrating GG-PEO Network as a Xerogel Matrix for Sustained Release of Sulpiride

    National Research Council Canada - National Science Library

    Hoosain, Famida G; Choonara, Yahya E; Kumar, Pradeep; Tomar, Lomas K; Tyagi, Charu; du Toit, Lisa C; Pillay, Viness

    2014-01-01

    The current study involved the development of a novel sustained release crosslinked semi-IPN xerogel matrix tablet prepared by chemical crosslinking of poly(ethylene) oxide (PEO) and gellan gum (GG...

  9. Inter and Intra Molecular Phase Separation Environment Effects on PI-PEO Block Copolymers for Batteries and Fuel Cells

    Science.gov (United States)

    Xue, Chen-Chen; Meador, Mary Ann B.; Eby, R. K.; Cheng, Stephen Z. D.; Ge, Jason J.; Cubon, Valerie A.

    2002-01-01

    Rod-coil molecules have been introduced as a novel type of block copolymers with unique microstructure due to their ability to self-assemble to various ordered morphologies on a nanometer length scale. These molecules, comprised two homo polymers joined together at one end, microphase separate into ordered, periodic arrays of spheres, cylinders in the bulk state and or solution. To get ordered structure in a reasonable scale, additional force field are applied, such as mechanical shearing, electric field and magnetic field. Recently, progress has made it a possible to develop a new class of polyimides (PI)-Polyethylene oxide (PEO) that are soluble in polar organic solvents. The solvent-soluble PI-PEO has a wide variety of applications in microelectronics, since these PI-PEO films exhibit a high degree of thermal and chemical stability. In this paper, we report the self-assembled ordered structure of PI-PEO molecules formed from concentrate solution.

  10. Synthesis, Characterization and Thermal Properties of Poly(ethylene oxide), PEO, Polymacromonomers via Anionic and Ring Opening Metathesis Polymerization

    National Research Council Canada - National Science Library

    George V Theodosopoulos; Christos Zisis; Georgios Charalambidis; Vasilis Nikolaou; Athanassios G Coutsolelos; Marinos Pitsikalis

    2017-01-01

    Branched polymers are a valuable class of polymeric materials. In the present study, anionic polymerization techniques were employed for the synthesis of low molecular weight poly(ethylene oxide) (PEO...

  11. Blends of POSS-PEO(n=4)(8) and high molecular weight poly(ethylene oxide) as solid polymer electrolytes for lithium batteries.

    Science.gov (United States)

    Zhang, Hanjun; Kulkarni, Sunil; Wunder, Stephanie L

    2007-04-12

    Solid polymer electrolyte blends were prepared with POSS-PEO(n=4)8 (3K), poly(ethylene oxide) (PEO(600K)), and LiClO4 at different salt concentrations (O/Li = 8/1, 12/1, and 16/1). POSS-PEO(n=4)8/LiClO4 is amorphous at all O/Li investigated, whereas PEO(600K) is amorphous only for O/Li = 8/1 and semicrystalline for O/Li = 12/1 and 16/1. The tendency of PEO(600K) to crystallize limited the amount of POSS-PEO(n=4)(8) that could be incorporated into the blends, so that the greatest incorporation of POSS-PEO(n=4)(8) occurred for O/Li = 8/1. Blends of POSS-PEO(n=4)(8)/PEO(600K)/LiClO4 (O/Li = 8/1 and 12/1) microphase separated into two amorphous phases, a low T(g) phase of composition 85% POSS-PEO(n=4)(8)/15% PEO(600K) and a high T(g) phase of composition 29% POSS-PEO(n=4)(8)/71% PEO(600K). For O/Li = 16/1, the blends contained crystalline (pure PEO(600K)), and two amorphous phases, one rich in POSS-PEO(n=4)(8) and one rich in PEO(600K). Microphase, rather than macrophase separation was believed to occur as a result of Li(+)/ether oxygen cross-link sites. The conductivity of the blends depended on their composition. As expected, crystallinity decreased the conductivity of the blends. For the amorphous blends, when the low T(g) (80/20) phase was the continuous phase, the conductivity was intermediate between that of pure PEO(600K) and POSS-PEO(n=4)(8). When the high T(g) (70/30, 50/50, 30/70, and 20/80) phase was the continuous phase, the conductivity of the blend and PEO(600K) were identical, and lower than that for the POSS-PEO(n=4)(8) over the whole temperature range (10-90 degrees C). This suggests that the motions of the POSS-PEO(n=4)(8) were slowed down by the dynamics of the long chain PEO(600K) and that the minor, low Tg phase was not interconnected and thus did not contribute to enhanced conductivity. At temperatures above T(m) of PEO(600K), addition of the POSS-PEO(n=4)(8) did not result in conductivity improvement. The highest RT conductivity, 8 x 10(-6) S

  12. In vitro degradation behavior and cytocompatibility of biodegradable AZ31 alloy with PEO/HT composite coating.

    Science.gov (United States)

    Tian, Peng; Liu, Xuanyong; Ding, Chuanxian

    2015-04-01

    Biodegradable magnesium-based implants have attracted much attention recently in orthopedic applications because of their good mechanical properties and biocompatibility. However, their rapid degradation in vivo will not only reduce their mechanical strength, but also induce some side effects, such as local alkalization and gas cavity, which may lead to a failure of the implant. In this work, a hydroxyapatite (HA) layer was prepared on plasma electrolytic oxidization (PEO) coating by hydrothermal treatment (HT) to fabricate a PEO/HT composite coating on biodegradable AZ31 alloy. The in vitro degradation behaviors of all samples were evaluated in simulated body fluid (SBF) and their surface cytocompatibility was also investigated by evaluating the adhesion and proliferation of osteoblast cells (MC3T3-E1). The results showed that the HA layer consisted of a dense inner layer and a needle-like outer layer, which successfully sealed the PEO coating. The in vitro degradation tests showed that the PEO/HT composite coating improved the corrosion resistance of AZ31 alloy in SBF, presenting nearly no severe local alkalization and hydrogen evolution. The lasting corrosion resistance of the PEO/HT composite coating may attribute to the new hydroxyapatite formation during the degradation process. Moreover, compared with AZ31 alloy and PEO coating, PEO/HT composite coating was more suitable for cells adhesion and proliferation, indicating improved surface cytocompatibility. The results show that the PEO/HT composite coating is promising as protective coating on biodegradable magnesium-based implants to enhance their corrosion resistance as well as improve their surface cytocompatibility for orthopedic applications.

  13. A comparative study on CdS: PEO and CdS: PMMA nanocomposite solid films

    Energy Technology Data Exchange (ETDEWEB)

    Padmaja, S. [Thin film centre, PSG College of Technology, Coimbatore (India); Jayakumar, S., E-mail: s_jayakumar_99@yahoo.com [Department of Physics, PSG Institute of Technology and Applied Research, Coimbatore (India); Balaji, R.; Vaideki, K. [Thin film centre, PSG College of Technology, Coimbatore (India)

    2016-08-15

    Cadmium Sulphide (CdS) nanoparticles were reinforced in Poly(ethylene Oxide) (PEO) and Poly(methyl methacrylate) (PMMA) matrices by in situ technique. The presence of CdS in PEO and PMMA matrix was confirmed using X-ray photoelectron spectroscopy (XPS). Fourier Transform Infrared spectroscopy (FTIR) analysis disclosed the co-ordination of CdS in the matrices. Thermal analysis of the nanocomposites was carried out using Differential Scanning calorimetric studies (DSC). The optical studies using UV–vis spectroscopy were carried out to find the band gap of the materials and the absorption onset. The CdS particle size in the matrices was found by Effective Mass Approximation (EMA) model using the band gap values and was confirmed by TEM studies. The surface trapped emissions of the nanocomposites were observed from the photoluminescence (PL) spectra. The distribution of CdS particles in the polymer matrices were presented by Atomic force microscopic studies (AFM).

  14. Ionic conductivity in the polymer electrolytes PEO/CF{sub 3}COONa

    Energy Technology Data Exchange (ETDEWEB)

    Delgado, I.; Chacon, M.; Vargas, R.A. [Valle Univ., Cali (Colombia). Dept. de Fisica; Castillo, J. [Ingenieria Electronica, Univ. del Quindio, Armenia (Colombia)

    2000-07-01

    In the present work, the electrical and thermal characterization of polymer electrolytes based on PEO/CF{sub 3}COONa are reported, which turn out to be good ionic conductors near room temperature (of the order 10{sup -4} {omega}{sup -1} cm{sup -1} for high salt concentrations). The variation of conductivity with temperature (plotted as ln {sigma} versus 1/T) and salt concentration suggests a complex formation. This is confirmed by differential scanning calorimetry (DSC), which also indicates that the blends are thermally stable up to approximately 480 K. The high conductivity and the single-phase behavior of the blends are explained in terms of the plastification effect of the organic salt on the PEO. (orig.)

  15. Composite polymer electrolyte based on PEO/Pvdf-HFP with MWCNT for lithium battery applications

    Science.gov (United States)

    Pradeepa, P.; Edwinraj, S.; Sowmya, G.; Kalaiselvimary, J.; Selvakumar, K.; Prabhu, M. Ramesh

    2016-05-01

    In the present study PEO and PVdF-HFP blend based composite polymer electrolytes (CPEs) has been prepared by using Multi Walled Carbon Nanotube (MWCNT), in order to examine the filler addition effect on the electrochemical properties. The complexed nanocomposite polymer electrolytes were obtained in the form of dimensionally stable and free standing films by using solution casting technique. The electrochemical properties of CPEs were measured by the AC impedance method. From the ionic conductivity results, the CPE containing MWCNT 2wt% showed the highest ionic conductivity with an excellent thermal stability at room temperature. The dielectric loss curve s for the sample 6.25wt% PEO: 18.75 wt% PVdF-HFP: 2wt% MWCNT reveal the low frequency β relaxation peak pronounced at high temperature, and it may caused by side group dipoles.

  16. Characterization of PEO-LiClO4-PC Solid Polymer Electrolytes

    Institute of Scientific and Technical Information of China (English)

    王标兵; 顾利霞; 靳茂全

    2001-01-01

    Plasticized poly (ethylene oxide )based electrolyte membranes of various compositions poly(ethylene oxide)/ Hthium perchlorate / propylene carbonate were prepared by solution casting. The thermogram, electrical conductivity and vibrational spectra were studied. DSC revealed that the plasticizer propylene carbonate content has influenced on the melting and transition temperature. The infrared spectroscopic study on the effect of PC on the poly (ethylene oxide) / lithium perchlorate E/ propylene carbonate systems shows that a suitable propylene carbonate content can impede association between lithium ions. Room temperature conductivity changed over 2 order of magnitude,increasing from 6.8 × 10-8Scm-1 of poly(ethylene oxide)/ lithium perchlorate (10/3, w/w) to 8.9 × 10-6Scm-1 of poly(ethylene oxide) / lithium perchlorate / propylenecarbonate (10/3/10, w/w/w). It seems that lithium ions only interact with PEO crystalline phase at the presence of PEO.

  17. PEO of pre-anodized Al-Si alloys: Corrosion properties and influence of sealings

    Science.gov (United States)

    Mohedano, M.; Matykina, E.; Arrabal, R.; Mingo, B.; Pardo, A.

    2015-08-01

    Voltage-controlled PEO coatings were developed on A356 aluminum alloys (gravity-cast and rheocast) with a pre-anodized layer. The influence of the alloy manufacturing process and the effect of Si-rich phase on the structure and composition of the oxide layers were evaluated using SEM, EDS and XRD. The pre-anodized oxide layer preserves the microstructure of the substrate due to the presence of secondary phases that have a different behavior relative to the matrix during anodizing. PEO coatings consisted of a mixture of α-Al2O3, γ-Al2O3 and mullite. The corrosion behavior and the effectiveness of different sealing techniques based on salts of nickel, cobalt, cerium and phosphonic acid were also studied. Post-treatments improved the hydrophobic properties of the coatings and showed a beneficial effect, significantly increasing the coating impedance and thereby reducing the susceptibility to corrosion.

  18. Effect of complexing salt on conductivity of PVC/PEO polymer blend electrolytes

    Indian Academy of Sciences (India)

    S Rajendran; Ravi Shanker Babu; M Usha Rani

    2011-12-01

    Solid polymer electrolyte membrane comprising poly(vinyl chloride) (PVC), poly(ehylene oxide) (PEO) and different lithium salts (LiClO4, LiBF4 and LiCF3SO3) were prepared by the solution casting technique. The effect of complexing salt on the ionic conductivity of the PVC/PEO host polymer is discussed. Solid polymer electrolyte films were characterized by X-ray diffraction, FTIR spectroscopy, TG/DTA and ac impedance spectroscopic studies. The conductivity studies of these solid polymer electrolyte (SPE) films are carried out as a function of frequency at various temperatures ranging from 302 K to 353 K. The maximum room temperature ionic conductivity is found to be 0.079 × 10-4 S cm-1 for the film containing LiBF4 as the complexing salt. The temperature dependence of the conductivity of polymer electrolyte films seems to obey the Vogel–Tamman–Fulcher (VTF) relation.

  19. Hydration of cations: a key to understanding of specific cation effects on aggregation behaviors of PEO-PPO-PEO triblock copolymers.

    Science.gov (United States)

    Lutter, Jacob C; Wu, Tsung-yu; Zhang, Yanjie

    2013-09-05

    This work reports results from the interactions of a series of monovalent and divalent cations with a triblock copolymer, poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (PEO-PPO-PEO). Phase transition temperatures of the polymer in the presence of chloride salts with six monovalent and eight divalent cations were measured using an automated melting point apparatus. The polymer undergoes a two-step phase transition, consisting of micellization of the polymer followed by aggregation of the micelles, in the presence of all the salts studied herein. The results suggest that hydration of cations plays a key role in determining the interactions between the cations and the polymer. The modulation of the phase transition temperature of the polymer by cations can be explained as a balance between three interactions: direct binding of cations to the oxygen in the polymer chains, cations sharing one water molecule with the polymer in their hydration layer, and cations interacting with the polymer via two water molecules. Monovalent cations Na(+), K(+), Rb(+), and Cs(+) do not bind to the polymer, while Li(+) and NH4(+) and all the divalent cations investigated including Mg(2+), Ca(2+), Sr(2+), Ba(2+), Co(2+), Ni(2+), Cu(2+), and Cd(2+) bind to the polymer. The effects of the cations correlate well with their hydration thermodynamic properties. Mechanisms for cation-polymer interactions are discussed.

  20. PEO-PPO-PEO/Poly(DL-lactide-co-caprolactone) Nanoparticles as Carriers for SN-38: Design, Optimization and Nano-Bio Interface Interactions.

    Science.gov (United States)

    Koliqi, Rozafa; Dimchevska, Simona; Geskovski, Nikola; Petruševski, Gjorgji; Chacorovska, Marina; Pejova, Biljana; Hristov, Delyan R; Ugarkovic, Sonja; Goracinova, Katerina

    2016-01-01

    Encapsulation of extremely hydrophobic substances such as SN-38 into nanoparticles, is a promising approach to solve the solubility issue and enable drug administration. Moreover, nanocarriers' tumor homing behavior, targeted and controlled release at the site of action will optimize therapeutic potency and decrease toxicity of the incorporated drug substance. However, the enormous drug hydrophobicity might limit the capacity for encapsulation as the premature drug precipitation will contribute to fast free drug crystal growth, low drug incorporation and huge waste of the active material. In this article we defined the optimal region for manufacturing of SN-38 loaded PEO-PPO-PEO/P(DL)LCL nanoparticles (NPs) with high efficacy of encapsulation, suitable particle size and different surface properties, using D-optimal design and nanoprecipitation as production method. Further we made an approach to investigate the interactions with macromolecules at the nano-bio interface which are predetermined by the physico-chemical and surface properties of the NPs, and are important determinants for the biological identity of the nanoparticles, the potential for evasion of the physiological barriers and the efficacy of localization at the site of action. Here we present in depth analysis of the behavior of two types of nanoparticles with different surface properties through structured protein interaction and bioreactivity experiments in order to presuppose NP performance and toxicological profile in biological environment.

  1. Ultraporous interweaving electrospun microfibers from PCL-PEO binary blends and their cellular response

    DEFF Research Database (Denmark)

    Chen, Menglin; Li, Yanfang; Besenbacher, Flemming

    2015-01-01

    Production of one dimensional nanomaterials with secondary morphology exhibiting unique functions is challenging. Here we report that a nanoscale immiscible polymer blend solution the electrojet can assemble into ultraporous interweaving microfibers. This intriguingly novel morphology originated...... from a blend of polycaprolactone (PCL) and polyethylene oxide (PEO) in a DCM-DMF mixed solution when the ratio between each component reached a threshold and when the electrospinning parameters were delicately controlled. We further investigated their influence on cell infiltration and colonization...

  2. Multiscale Simulations of Lamellar PS–PEO Block Copolymers Doped with LiPF6 Ions

    KAUST Repository

    Sethuraman, Vaidyanathan

    2017-06-02

    We report the results of atomistic simulations of the structural equilibrium properties of PS–PEO block copolymer (BCP) melt in the ordered lamellar phase doped with LiPF6 salt. A hybrid simulation strategy, consisting of steps of coarse-graining and inverse coarse-graining, was employed to equilibrate the melt at an atomistic resolution in the ordered phase. We characterize the structural distributions between different atoms/ions and compare the features arising in BCPs against the corresponding behavior in PEO homopolymers for different salt concentrations. In addition, the local structural distributions are characterized in the lamellar phase as a function of distance from the interface. The cation–anion radial distribution functions (RDF) display stronger coordination in the block copolymer melts at high salt concentrations, whereas the trends are reversed for low salt concentrations. Radial distribution functions isolated in the PEO and PS domains demonstrate that the stronger coordination seen in BCPs arises from the influence of both the higher fraction of ions segregated in the PS phase and the influence of interactions in the PS domain. Such a behavior also manifests in the cation–anion clusters, which show a larger fraction of free ions in the BCP. While the average number of free anions (cations) decreases with increasing salt concentration, higher order aggregates of LiPF6 increase with increasing salt concentration. Further, the cation–anion RDFs display spatial heterogeneity, with a stronger cation–anion binding in the interfacial region compared to bulk of the PEO domain.

  3. Dielectric dispersion and relaxations in (PVA-PEO)-ZnO polymer nanocomposites

    Science.gov (United States)

    Choudhary, Shobhna

    2017-10-01

    The organic-inorganic nanocomposite materials consisted of poly(vinyl alcohol) (PVA) and poly(ethylene oxide) (PEO) blend matrix (50/50 wt%) dispersed with zinc oxide (ZnO) nanoparticles have been prepared by the aqueous solution-cast method. The dielectric dispersion and relaxation processes in these polymer nanocomposite (PNC) films (i.e., (PVA-PEO)-x wt% ZnO; x = 0, 1, 3 or 5) have been investigated over the frequency range from 20 Hz to 1 MHz by employing the dielectric relaxation spectroscopy (DRS). Influence of ZnO contents on the complex dielectric permittivity, electrical conductivity, electric modulus and impedance properties of these PNC materials has been explored. The dielectric permittivity and the relaxation time values corresponding to polymers cooperative chain segmental motion significantly change with the variation of ZnO contents in the PVA-PEO blend matrix at ambient temperature. The temperature dependent relaxation times and dc conductivity values of (PVA-PEO)-3 wt% ZnO film have been investigated which obey the Arrhenius behaviour. The dielectric permittivity of the film as a function of temperature exhibits linear behaviour at radio frequencies and non-linear variation at lower audio frequencies. X-ray diffraction measurements confirm a huge decrease in crystalline phase of the polymer blend matrix on the addition of 1 wt% ZnO nanoparticles. These PNC materials have low values of dielectric permittivity and electrical conductivity which confirm their suitability as novel flexible-type polymer nanodielectric for the insulation in microelectronic devices, whereas the fast chain segmental dynamics and high amorphous phase reveal these materials as a potential candidate for the preparation of nanocomposite solid polymer electrolytes.

  4. Production of Prednisolone by Pseudomonas oleovorans Cells Incorporated Into PVP/PEO Radiation Crosslinked Hydrogels

    Directory of Open Access Journals (Sweden)

    Abeer Abd El-Hady

    2004-01-01

    Full Text Available In order to rise the yield of prednisolone from hydrocortisone, the Pseudomonas oleovorans cells were entrapped into radiation crosslinked poly (vinyl pyrrolidone/poly(ethylene oxide (PVP/PEO hydrogel of different gel contents. The factors affecting the gel content and swelling behavior of the polymeric gel, such as polymer composition, polymer blend concentration, and irradiation doses, were investigated. The formation of gels having a good strength with the ability to retain a desirable amount of water in their three-dimensional network can be achieved by using PVP/PEO copolymer of composition (90:10 and concentration of 15% prepared at 20 kGy irradiation dose. At these conditions the prepared hydrogel is considered the most favorable one that gave the highest hydrocortisone bioconversion and prednisolone yield, 81% and 62.8%, respectively. The improvement of prednisolone yield was also achieved by increasing substrate concentration. Maximum hydrocortisone bioconversion (86.44 was obtained at 18 hours by using substrate concentration of 30 mg. Reusability of immobilized Pseudomonas oleovorans entrapped into PVP/PEO copolymer hydrogel was studied. The results indicated that the transformation capacity of hydrocortisone to prednisolone highly increased by the repeated use of copolymer for 4 times. This was accompanied by an increase in prednisolone yield to 89% and the bioconversion of hydrocortisone was 98.8%.

  5. Sealing of PEO Coated AZ91 Magnesium Alloy Using La-Based Solutions

    Directory of Open Access Journals (Sweden)

    Luca Pezzato

    2017-01-01

    Full Text Available In this work, solutions containing lanthanum salts were used for a post-treatment of sealing to increase the corrosion resistance of PEO coated AZ91 alloy. PEO coatings were produced on samples of AZ91 magnesium alloy using an alkaline solution containing sodium hydroxide, sodium phosphates, and sodium silicates. The sealing treatment was performed in a solution containing 12 g/L of La(NO33 at pH 4 at different temperatures and for different treatment times. Potentiodynamic polarization test, an EIS test, showed that the sealing treatment with solution containing lanthanum nitrate caused a remarkable increase in the corrosion resistance. The corrosion behavior was correlated with the surface morphology and elemental composition evaluated with scanning electron microscope (SEM, X-ray diffraction (XRD, and X-ray photoelectron spectroscopy (XPS. In particular, the sealing treatment at 50°C for 30 min resulted in being the most promising to increase the corrosion properties of PEO treated samples because of the formation of a homogeneous sealing layer, mainly composed of La(OH3.

  6. Temperature responsive complex coacervate core micelles with a PEO and PNIPAAm corona.

    Science.gov (United States)

    Voets, Ilja K; Moll, Puck M; Aqil, Abdelhafid; Jérôme, Christine; Detrembleur, Christophe; Waard, Pieter de; Keizer, Arie de; Stuart, Martien A Cohen

    2008-09-01

    In aqueous solutions at room temperature, poly( N-methyl-2-vinyl pyridinium iodide)- block-poly(ethylene oxide), P2MVP 38- b-PEO 211 and poly(acrylic acid)- block-poly(isopropyl acrylamide), PAA 55- b-PNIPAAm 88 spontaneously coassemble into micelles, consisting of a mixed P2MVP/PAA polyelectrolyte core and a PEO/PNIPAAm corona. These so-called complex coacervate core micelles (C3Ms), also known as polyion complex (PIC) micelles, block ionomer complexes (BIC), and interpolyelectrolyte complexes (IPEC), respond to changes in solution pH and ionic strength as their micellization is electrostatically driven. Furthermore, the PNIPAAm segments ensure temperature responsiveness as they exhibit lower critical solution temperature (LCST) behavior. Light scattering, two-dimensional 1H NMR nuclear Overhauser effect spectrometry, and cryogenic transmission electron microscopy experiments were carried out to investigate micellar structure and solution behavior at 1 mM NaNO 3, T = 25, and 60 degrees C, that is, below and above the LCST of approximately 32 degrees C. At T = 25 degrees C, C3Ms were observed for 7 coacervate shell, and a PEO corona.

  7. Supramolecular gels of poly-α-cyclodextrin and PEO-based copolymers for controlled drug release.

    Science.gov (United States)

    Simões, Susana M N; Veiga, Francisco; Ribeiro, Ana C F; Figueiras, Ana R; Taboada, Pablo; Concheiro, Angel; Alvarez-Lorenzo, Carmen

    2014-08-01

    The aim of this work was to prepare syringeable supramolecular gels of α-cyclodextrin-polymer (poly-αCD) with various poly(ethylene oxide) (PEO)-based copolymers, which can be suitable to form depots for controlled drug release. A series of water-soluble poly-αCDs was synthesized from αCD by crosslinking with epichlorohydrin in alkaline medium. The chemical composition of the polymers was characterized by NMR (αCD content>53%) and the molecular weight was evaluated using static light scattering (SLS). Supramolecular assemblies occurred by mixing poly-αCD (20-40% w/v) with a PEO-based polymer (i.e., PEG, Pluronic® F127 or Tetronic® 908) (10-15% w/v). Phase separation was observed and the αCD content in each phase was determined by means of the phenol-sulfuric acid colorimetric method. Formation of poly-αCD/PEO-based polymer 3D-supramolecular complexes was confirmed by diffusion-ordered NMR spectroscopy (DOSY) and X-ray diffractometry. The supramolecular assemblies showed good cytocompatibility against SAOS-2 cells and in the HET-CAM test. The supramolecular gels were able to sustain the release of vancomycin for at least 5 days at 37 °C, more efficiently than dispersions of each polymer component in separate. These results open new possibilities in the design of novel controlled delivery systems for the treatment of bone infections.

  8. Effect of Eutectic Concentration on Conductivity in PEO:LiX Based Solid Polymer Electrolytes

    Science.gov (United States)

    Zhan, Pengfei; Ganapatibhotla, Lalitha; Maranas, Janna

    Polyethylene oxide (PEO) and lithium salt based solid polymer electrolytes (SPEs) have been widely proposed as a substitution for the liquid electrolyte in Li-ion batteries. As salt concentration varies, these systems demonstrate rich phase behavior. Conductivity as a function of salt concentration has been measured for decades and various concentration dependences have been observed. A PEO:LiX mixture can have one or two conductivity maximums, while some mixtures with salt of high ionic strength will have higher conductivity as the salt concentration decrease. The factors that affect the conductivity are specific for each sample. The universal factor that affects conductivity is still not clear. In this work, we measured the conductivity of a series of PEO:LiX mixtures and statistical analysis shows conductivity is affected by the concentration difference from the eutectic concentration (Δc). The correlation with Δc is stronger than the correlation with glass transition temperature. We believe that at the eutectic concentration, during the solidification process, unique structures can form which aid conduction. Currently at Dow Chemical.

  9. Preparation of antibacterial PVA and PEO nanofibers containing Lawsonia Inermis (henna) leaf extracts.

    Science.gov (United States)

    Avci, H; Monticello, R; Kotek, R

    2013-01-01

    Concerns about health issues and environmental pollution stimulate research to find new health and hygiene related products with healing properties and minimum negative effect on the environment. Development of new, natural antibacterial agents has become one of the most important research areas to combat some pathogens such as Gram- positive and Gram-negative bacteria, fungi, algae, yeast, and some microorganisms which cause serious human infections. Lawsonia Inermis (henna) leaf extracts for preparation of antibacterial poly(ethylene oxide) (PEO) and poly(vinyl alcohol) (PVA) nanofibers via electrospinning technique were investigated. PEO and PVA based electrospun fibers containing henna extract were verified by the appearance of FTIR peaks corresponding to the pure extract. Our study demonstrates that 2.793 wt.% Li in PVA and PEO based solutions showed bactericidal effects against Staphylococcus aureus and bacteriostatic action to Escherichia coli. Concentrations of henna leaf extract strongly impacted antibacterial activities against both bacteria. Henna leaves have a great potential to be used as a source of a potent eco-friendly antimicrobial agent.

  10. Ion pair formation and its effect in PEO:Mg solid polymer electrolyte system

    Science.gov (United States)

    Jaipal Reddy, M.; Chu, Peter P.

    In poly(ethylene oxide) (PEO) based solid polymer electrolytes, the interaction between cations and the ether oxygen plays a major role in ion conductivity. Measurements with differential scanning calorimetry (DSC) illustrated clearly the modification of the PEO crystalline structure with increasing content of magnesium salt. FTIR spectral studies suggest interaction of Mg 2+ cations with the ether oxygen of PEO, where a 1100 cm -1 broad band corresponds to COC stretching and severe deformation occurs. A spectral band at ˜623 cm -1 corresponds to the ClO 4- anion and shows the growth of a shoulder at a higher wave number with increasing salt content. The apparent new envelope at ˜634.5 cm -1 clearly indicates ClO 4--Mg 2+ ion pairing. Ionic conductivity increases with salt content, and is optimized at 15 wt.% Mg salt (O:Mg ratio 28:1). The decrease in ion conductivity at higher salt contents is due to ion-ion association, which leads to ion pair formation (i.e. aggregation of ionic salt) and retards the motion of ions.

  11. Surface characterisation of Ti-15Mo alloy modified by a PEO process in various suspensions.

    Science.gov (United States)

    Kazek-Kęsik, Alicja; Dercz, Grzegorz; Kalemba, Izabela; Suchanek, Katarzyna; Kukharenko, Andrey I; Korotin, Danila M; Michalska, Joanna; Krząkała, Agnieszka; Piotrowski, Jerzy; Kurmaev, Ernst Z; Cholakh, Seif O; Simka, Wojciech

    2014-06-01

    This paper reports on the surface modification of a Ti-15Mo alloy by plasma electrolytic oxidation (PEO). This process was carried out in solutions of 0.1M Ca(H2PO2)2 with various concentrations of tricalcium phosphate (Ca3(PO4)2), wollastonite (CaSiO3), or silica (SiO2) using voltages of up to 350V. The surface microstructure (SEM, cross-section of coating), roughness and chemical composition (energy-dispersive X-ray spectroscopy, thin layer X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy) of the porous oxide layers were investigated. The concentration of powder added to the solution changed the chemical composition and morphology of PEO coatings on the Ti-15Mo alloy surface. Calcium and phosphorous compounds were detected in the coatings formed on the substrate by the PEO process at 300V. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Gamma-irradiation synthesis of iron oxide nanoparticles in the presence of PEO, PVP or CTAB

    Science.gov (United States)

    Jurkin, Tanja; Gotić, Marijan; Štefanić, Goran; Pucić, Irina

    2016-07-01

    Black hydrogels were synthesized using γ-irradiation of poly(ethylene oxide) (PEO)/iron(III) chloride precursor solutions. The magnetic properties of such hydrogels were improved by adding 2-propanol as a hydroxyl scavenger and/or NaBH4 as a strong chemical reducing agent; however, the rigidity and compactness of thus synthesized PEO hydrogels deteriorated. The magnetic suspension containing pure magnetite nanoparticles was obtained using γ-irradiation of an Fe(III)/PEO deoxygenated aqueous solution in the presence of 2-propanol and NaBH4. The γ-irradiation of an iron(III) chloride aqueous precursor solution in the presence of PVP produced a magnetic suspension due to the formation of a small amount of δ-FeOOH (feroxyhyte). The γ-irradiation of Fe(III)/CTAB (cetyltrimethylammonium bromide) aqueous solutions favored the formation of goethite. γ-irradiation in the presence of 2-propanol increased the yield of rod-like goethite nanoparticles. A small amount of δ-FeOOH found in the Fe(III)/PVP and Fe(III)/CTAB suspensions suggests the formation of Fe(OH)2upon γ-irradiation, which then under atmospheric conditions rapidly oxidized into δ-FeOOH.

  13. Stearic acid and high molecular weight PEO as matrix for the highly water soluble metoprolol tartrate in continuous twin-screw melt granulation

    OpenAIRE

    Monteyne, Tinne; Adriaensens, Peter; Brouckaert, Davinia; Remon, Jean-Paul; Vervaet, Chris; De Beer, Thomas

    2016-01-01

    Granules with release-sustaining properties were developed by twin screw hot melt granulation (HMG) using a combination of stearic acid (SA) and high molecular weight polyethylene oxide (PEO) as matrix for a highly water soluble model drug, metoprolol tartrate (MPT). Earlier studies demonstrated that mixing molten SA and PEO resulted in hydrogen bond formation between hydroxyl groups of fatty acid molecules and ether groups in PEO chains. These molecular interactions might be beneficial in or...

  14. Effect of current mode on PEO treatment of magnesium in Ca- and P-containing electrolyte and resulting coatings

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Yonghao [Department of Materials Science and Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom); Yerokhin, Aleksey, E-mail: a.yerokhin@sheffield.ac.uk [Department of Materials Science and Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom); National University of Science and Technology “MISIS”, Leninsky Prospect, 4, Moscow 119049 (Russian Federation); Matthews, Allan [Department of Materials Science and Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom)

    2014-10-15

    Highlights: • MgO-Na{sub 4}Ca(PO{sub 3}){sub 6} coatings produced on cp-Mg in both PUP- and PBP-PEO modes. • Negative biasing affects PEO processing of cp-Mg in Ca(OH){sub 2}-Na{sub 3}PO{sub 4} electrolyte. • Thicker and macro defect-free PUP-PEO coatings provide better corrosion protection. • Corrosion mechanisms of PEO-treated cp-Mg in SBF discussed. - Abstract: Plasma electrolytic oxidation (PEO) coatings were produced on commercially pure magnesium in a biologically friendly electrolyte composed of 2 g L{sup −1} Ca(OH){sub 2} and 12 g L{sup −1} Na{sub 3}PO{sub 4}·12H{sub 2}O using pulsed unipolar and bipolar current regimes with negative biasing varying from 0 to 20 mA cm{sup −2}. Analysis of voltage transients was performed to characterise the PEO processes. The coating morphology and phase composition were studied by scanning electron microscopy and X-ray diffraction technique, respectively. In vitro corrosion performance of the coatings was evaluated in a simulated body fluid at 37 ± 1 °C, using electrochemical techniques including open circuit potential monitoring, electrochemical impedance spectroscopy and potentiodynamic polarisation scans. The influence of the negative biasing on the PEO process and resulting coating characteristics is discussed. Unlike generally recognised beneficial effects of the negative biasing in PEO treatments of some other metal-electrolyte systems, it was found that detrimental effects are induced to the coatings on cp-Mg produced in the studied electrolyte when the negative current amplitude increases, which may be attributed to hydrogen liberation at the coating/substrate interface during the negative biasing cycles. As a result, a deterioration of vitro corrosion performance was observed for the pulsed bipolar PEO coatings compared to those produced using the pulsed unipolar regime which provides better quality coatings.

  15. Preparation and characterization of novel thermoset polyimide and polyimide-peo doped with LiCF3SO3

    Directory of Open Access Journals (Sweden)

    M. H. Ugur

    2014-02-01

    Full Text Available This paper deals with the synthesis and characterization of a new type of anhydrous ionic conducting lithium doped membranes consist of polyimide (PI, poly (ethylene oxide (PEO and lithium trifluoromethanesulfonate (LiCF3SO3 for solid polymer electrolyte (SPE. For this purpose, different molar ratios of lithium salt (Li-salt solution are added into poly (amic acid (PAA intermediate prepared from the reaction of 3,3',4,4'-benzophenon tetracarboxylic dianhydride (BTDA and 4,4'-oxydianiline (ODA. PEO is incorporated into PAA since it forms more stable complexes and possess high ionic conductivities. Then, Li-salt containing PAA solutions are imidized by thermal process. The effect of interaction between host polymer and Li-salt is characterized by FT-IR (Fourier Transform Infrared spectroscopy and SEM (scanning electron micrsocopy. The conductivities of Li-salt and PEO containing PI composite membranes are in the range of 10–7–10–5 S•cm–1. The conductivity increases with incorporation of PEO. Thermogravimetric analysis results reveal that the PI/PEO/LiCF3SO3 composite polymer electrolyte membranes are thermally stable up to 500°C.

  16. Corrosion properties of plasma electrolytic oxidation coatings on an aluminium alloy – The effect of the PEO process stage

    Energy Technology Data Exchange (ETDEWEB)

    Dehnavi, Vahid, E-mail: vdehnavi@uwo.ca [Department of Chemical and Biochemical Engineering, University of Western Ontario, London, N6A 5B9 ON (Canada); Shoesmith, David W., E-mail: dwshoesm@uwo.ca [Surface Science Western, Department of Chemistry, University of Western Ontario, London, N6A 5B7 ON (Canada); Luan, Ben Li, E-mail: Ben.Luan@nrc-cnrc.gc.ca [National Research Council Canada, 800 Collip Circle, London, N6G4X8 ON (Canada); Department of Chemistry, University of Western Ontario, London, N6A 5B7 ON (Canada); Yari, Mehdi, E-mail: myari@uwo.ca [Department of Chemistry, University of Western Ontario, London, N6A 5B7 ON (Canada); Liu, Xing Yang, E-mail: XingYang.Liu@nrc-cnrc.gc.ca [National Research Council Canada, 800 Collip Circle, London, N6G4X8 ON (Canada); Rohani, Sohrab, E-mail: srohani@uwo.ca [Department of Chemical and Biochemical Engineering, University of Western Ontario, London, N6A 5B9 ON (Canada)

    2015-07-01

    Plasma electrolytic oxidation (PEO) coatings were grown on an aluminium alloy substrate using different processing parameters which enabled samples to be coated to different stages of the PEO process. Electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR) techniques were employed to investigate the impedance properties of the resulting oxide coatings which will determine the corrosion performance of the coated alloy. Scanning electron microscopy was used to relate the morphology of the coatings with their corrosion performance. A direct relationship was found between the stage of the PEO process, which affects the microstructure of the coatings, and the corrosion performance. Coating thickness and phase composition did not have any measurable influence on coating corrosion performance. To some degree corrosion performance could be tailored by the processing parameters. - Highlights: • Corrosion performance of PEO coatings was found to be dependent on coating stage. • The PEO stage determined by the process parameters controlled coatings morphology. • Samples coated at the end of stage 3 demonstrated better corrosion properties. • Coating thickness and phase composition showed no influence on corrosion resistance.

  17. Electrochemical Performance of PEO10LiX-Li2TiO3 Composite Polymer Electrolytes

    Institute of Scientific and Technical Information of China (English)

    LU,Mi(路密); SHI,Peng-Fei(史鹏飞)

    2004-01-01

    The conductivities of polyethylene oxide (PEO)-based polymer electrolytes (PE) can be improved by the addition of inorganic inert powder. The composite polymer electrolytes (CPE) PEO10LiX (X= or )-Li2TiO3 were prepared by solution casting with inorganic solid electrolyte Li2TiO3 powder as a filler. Results showed that the conductivities of PEO10LiClO4-3wt% Li2TiO3 and PEO10LiN(CF3SO2)2-10wt% Li2TiO3 at 30 ℃ were 8.6×10-6 and 5.6×10-5 S·cm-1, respectively. The conductivities of CPE increased with the decrease of filler's particle size. The ionic conduction mechanism analysis showed that there may be three conduction routes in the CPE, i.e., PEO bulk, polymer-filler interface and Li2TiO3 crystal.

  18. Effect of current mode on PEO treatment of magnesium in Ca- and P-containing electrolyte and resulting coatings

    Science.gov (United States)

    Gao, Yonghao; Yerokhin, Aleksey; Matthews, Allan

    2014-10-01

    Plasma electrolytic oxidation (PEO) coatings were produced on commercially pure magnesium in a biologically friendly electrolyte composed of 2 g L-1 Ca(OH)2 and 12 g L-1 Na3PO4·12H2O using pulsed unipolar and bipolar current regimes with negative biasing varying from 0 to 20 mA cm-2. Analysis of voltage transients was performed to characterise the PEO processes. The coating morphology and phase composition were studied by scanning electron microscopy and X-ray diffraction technique, respectively. In vitro corrosion performance of the coatings was evaluated in a simulated body fluid at 37 ± 1 °C, using electrochemical techniques including open circuit potential monitoring, electrochemical impedance spectroscopy and potentiodynamic polarisation scans. The influence of the negative biasing on the PEO process and resulting coating characteristics is discussed. Unlike generally recognised beneficial effects of the negative biasing in PEO treatments of some other metal-electrolyte systems, it was found that detrimental effects are induced to the coatings on cp-Mg produced in the studied electrolyte when the negative current amplitude increases, which may be attributed to hydrogen liberation at the coating/substrate interface during the negative biasing cycles. As a result, a deterioration of vitro corrosion performance was observed for the pulsed bipolar PEO coatings compared to those produced using the pulsed unipolar regime which provides better quality coatings.

  19. Improved electrical properties of Fe nanofiller impregnated PEO + PVP:Li+ blended polymer electrolytes for lithium battery applications

    Science.gov (United States)

    Naveen Kumar, K.; Saijyothi, K.; Kang, Misook; Ratnakaram, Y. C.; Hari Krishna, K.; Jin, Dahee; Lee, Yong Min

    2016-07-01

    Solid polymer-blended electrolyte films of polyethylene oxide (PEO) + polyvinyl pyrrolidone (PVP)/lithium perchlorate embedded with iron (Fe) nanofiller in different concentrations have been synthesized by a solution casting method. The semicrystalline nature of these polymer electrolyte films has been confirmed from their XRD profiles. Polymer complex formation and ion-polymer interactions are systematically studied by FTIR and laser Raman spectral analysis. Surface morphological studies are carried out from SEM analysis. Dispersed Fe nanofiller size evaluation study has been carried out using transmission electron microscopy (TEM). In order to evaluate the thermal stability, decomposition temperature, and thermogravimetric dynamics, we carried out the TG/DTA measurement. Upon addition of Fe nanofiller to the PEO + PVP/Li+ electrolyte system, it was found to result in the enhancement of ionic conductivity. The maximum ionic conductivity has been set up to be 1.14 × 10-4 Scm-1 at the optimized concentration of 4 wt% Fe nanofiller-embedded PEO + PVP/Li+ polymer electrolyte nanocomposite at an ambient temperature. PEO + PVP/Li+ + Fe nanofiller (4 wt%) cell exhibited better performance in terms of cell parameters. Based on the cell parameters, the 4 wt% Fe nanofiller-dispersed PEO + PVP/Li+ polymer electrolyte system could be suggested as a perspective candidate for solid-state battery applications.

  20. Surface modification of chitosan/PEO nanofibers by air dielectric barrier discharge plasma for acetylcholinesterase immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Dorraki, Naghme, E-mail: n.dorraki@web.sbu.ac.ir [Laser and Plasma Research Institute, Shahid Beheshti University, Evin 1983963113, Tehran (Iran, Islamic Republic of); Safa, Nasrin Navab [Laser and Plasma Research Institute, Shahid Beheshti University, Evin 1983963113, Tehran (Iran, Islamic Republic of); Jahanfar, Mehdi [Protein Research Center, Shahid Beheshti University, Evin 1983963113, Tehran (Iran, Islamic Republic of); Ghomi, Hamid [Laser and Plasma Research Institute, Shahid Beheshti University, Evin 1983963113, Tehran (Iran, Islamic Republic of); Ranaei-Siadat, Seyed-Omid [Protein Research Center, Shahid Beheshti University, Evin 1983963113, Tehran (Iran, Islamic Republic of)

    2015-09-15

    Highlights: • We used an economical and effective method for surface modification. • Chitosan/PEO nanofibrous membranes were modified by air-DBD plasma. • The most NH{sub 3}{sup +} group was generated on the 6 min plasma modified membrane. • We immobilized acetylcholinesterase on the plasma modified and unmodified membranes. • More enzyme activity was detected on the modified membrane by plasma. - Abstract: There are different methods to modify polymer surfaces for biological applications. In this work we have introduced air-dielectric barrier discharge (DBD) plasma at atmospheric pressure as an economical and safe method for modifying the surface of electrospun chitosan/PEO (90/10) nanofibers for acetylcholinesterase (AChE) immobilization. According to the contact angle measurement results, the nanofibers become highly hydrophilic when they are exposed to the DBD plasma for 6 min in compared to unmodified membrane. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) results reveal hydroxyl, C=O and NH{sub 3}{sup +} polar groups increment after 6 min plasma treatment. Contact angle measurements and ATR-FTIR results are confirmed by X-ray photoelectron spectroscopy (XPS). AChE at pH 7.4 carries a negative charge and after immobilization on the surface of plasma-treated nanofibrous membrane attracts the NH{sub 3}{sup +} group and more enzyme activity is detected on the plasma-modified nanofibers for 6 min in compared to unmodified nanofibers. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) are used for the surface topography and morphology characterization. The results have proved that air-DBD plasma is a suitable method for chitosan/PEO nanofibrous membrane modification as a biodegradable and functionalized substrate for enzyme immobilization.

  1. How molecular internal-geometric parameters affect PB-PEO polymersome size in aqueous solution

    DEFF Research Database (Denmark)

    Habel, Joachim Erich Otto; Ogbonna, Anayo; Larsen, Nanna

    2016-01-01

    is the ratio between the hydrophilic block volume and the entire diblock volume. However the polymersome size distribution also depends on molecular weight (Mn) and in order to gain insight on how f and Mn together determine polymersome size, we prepared PB-PEO diblock copolymers with different block lengths...... and analyzed vesicle morphology via Dynamic light scattering (DLS) and Freeze-fracture transmission electron microscopy (FF-TEM). We found three main regimes: high f / low Mn with polymersomes of mixed diameter, high f / high Mn with mainly large polymersomes and low f, with mainly small polymersomes...

  2. Studies on the Dielectric and Transport Properties of PEO/Chitosan Proton Conducting Polymer Electrolyte

    Institute of Scientific and Technical Information of China (English)

    M.F.Z.Abdul; Kadir; A.K.Arof

    2007-01-01

    1 Results The effect of ammonium nitrate (NH4NO3) content in 40 wt.% PEO and 60 wt.% chitosan blend has been analyzed in this study.The sample containing 40 wt.% NH4NO3 exhibited the highest room temperature conductivity.In order to ascertain that water does not influence the conductivity,the samples were dried in a dessicator and the conductivity determined daily until it shows a constant value.Results are as shown in Fig.1.Samples containing other salt concentrations were also kept in the dessicator f...

  3. Enhanced electrical transport in ionic liquid dispersed TMAI-PEO solid polymer electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Neha [Physics Department, Birla Institute of Technology and Science, Pilani-333031, Rajasthan, India and Department of Physics, JECRC University, Jaipur-303905, Rajasthan (India); Rathore, Munesh, E-mail: adalvi@pilani.bits-pilani.ac.in; Dalvi, Anshuman, E-mail: adalvi@pilani.bits-pilani.ac.in [Physics Department, Birla Institute of Technology and Science, Pilani-333031, Rajasthan (India); Kumar, Anil [Chemistry Department, Birla Institute of Technology and Science, Pilani-333031, Rajasthan (India)

    2014-04-24

    A polymer composite is prepared by dispersing ionic liquid [Bmim][BF{sub 4}] in Polyethylene oxide-tetra methyl ammonium iodide composite and subsequent microwave treatment. X-ray diffraction patterns confirm the composite nature. To explore possibility of proton conductivity in these films, electrical transport is studied by impedance spectroscopy and DC polarization. It is revealed that addition of ionic liquid in host TMAI-PEO solid polymer electrolyte enhances the conductivity by ∼ 2 orders of magnitude. Polarization measurements suggest that composites are essentially ion conducting in nature. The maximum ionic conductivity is found to be ∼2 × 10{sup −5} for 10 wt % ionic liquid.

  4. Isoporous PS-b-PEO ultrafiltration membranes via self-assembly and water-induced phase separation

    KAUST Repository

    Karunakaran, Madhavan

    2014-03-01

    A simple and efficient approach towards the fabrication of a skinned membrane with highly ordered pores in the nanometer range is presented here. We successfully combined the self-assembly of PS-b-PEO block copolymer and water induced phase separation for the preparation of isoporous PS-b-PEO block copolymer membranes. We produced for the first time asymmetric isoporous PS-b-PEO membranes with a 100nm thin isoporous separating layer using water at room temperature as coagulant. This was possible by careful selection of the block lengths and the solvent system. FESEM, AFM and TEM measurements were employed to characterize the nanopores of membranes. The pure water fluxes were measured and the flux of membrane was exceptionally high (around 800Lm-2h-1bar-1). Protein rejection measurements were carried out for this membrane and the membrane had a retention of about 67% of BSA and 99% of γ-globulin. © 2013 Elsevier B.V.

  5. Synthesis and chromatography-free purification of PNA-PEO conjugates for the functionalisation of gold sensors.

    Science.gov (United States)

    Dettin, Monica; Silvestri, Davide; Danesin, Roberta; Cretaio, Erica; Picariello, Gianluca; Casarin, Elisabetta; Sonato, Agnese; Romanato, Filippo; Morpurgo, Margherita

    2012-09-13

    Peptide Nucleic Acids (PNAs) linked to high molecular weight (MW) poly(ethylene oxide) (PEO) derivatives could be useful conjugates for the direct functionalisation of gold surfaces dedicated to Surface Plasmon Resonance (SPR)-based DNA sensing. However their use is hampered by the difficulty to obtain them through a convenient and economical route. In this work we compared three synthetic strategies to obtain PNA-high MW PEO conjugates composed of (a) a 15-mer PNA sequence as the probe complementary to genomic DNA of ]Mycobacterium tuberculosis, (b) a PEO moiety (2 or 5 KDa MW) and (c) a terminal trityl-protected thiol necessary (after acidic deprotection) for grafting to gold surfaces. The 15-mer PNA was obtained by solid-phase synthesis. Its amino terminal group was later condensed to bi-functional PEO derivatives (2 and 5 KDa MW) carrying a Trt-cysteine at one end and a carboxyl group at the other end. The reaction was carried out either in solution, using HATU or PyOxim as coupling agents, or through the solid-phase approach, with 49.6%, 100% and 5.2% yield, respectively. A differential solvent extraction strategy for product purification without the need for chromatography is described. The ability of the 5 KDa PEO conjugate to function as a probe for complementary DNA detection was demonstrated using a Grating-Coupling Surface Plasmon Resonance (GC-SPR) system. The optimized PEO conjugation and purification protocols are economical and simple enough to be reproduced also within laboratories that are not highly equipped for chemical synthesis.

  6. Synthesis and Chromatography-Free Purification of PNA-PEO Conjugates for the Functionalisation of Gold Sensors

    Directory of Open Access Journals (Sweden)

    Filippo Romanato

    2012-09-01

    Full Text Available Peptide Nucleic Acids (PNAs linked to high molecular weight (MW poly(ethylene oxide (PEO derivatives could be useful conjugates for the direct functionalisation of gold surfaces dedicated to Surface Plasmon Resonance (SPR-based DNA sensing. However their use is hampered by the difficulty to obtain them through a convenient and economical route. In this work we compared three synthetic strategies to obtain PNA-high MW PEO conjugates composed of (a a 15-mer PNA sequence as the probe complementary to genomic DNA of Mycobacterium tuberculosis, (b a PEO moiety (2 or 5 KDa MW and (c a terminal trityl-protected thiol necessary (after acidic deprotection for grafting to gold surfaces. The 15-mer PNA was obtained by solid-phase synthesis. Its amino terminal group was later condensed to bi-functional PEO derivatives (2 and 5 KDa MW carrying a Trt-cysteine at one end and a carboxyl group at the other end. The reaction was carried out either in solution, using HATU or PyOxim as coupling agents, or through the solid-phase approach, with 49.6%, 100% and 5.2% yield, respectively. A differential solvent extraction strategy for product purification without the need for chromatography is described. The ability of the 5 KDa PEO conjugate to function as a probe for complementary DNA detection was demonstrated using a Grating-Coupling Surface Plasmon Resonance (GC-SPR system. The optimized PEO conjugation and purification protocols are economical and simple enough to be reproduced also within laboratories that are not highly equipped for chemical synthesis.

  7. Ordered nanostructure of PS-b-PEO copolymer by solvent annealing with mixture of benzene/water vapor and its micropattern fabrication.

    Science.gov (United States)

    Kim, Tae Hee; Hwang, Jiyoung; Acharya, Himadri; Park, Cheolmin

    2010-10-01

    We investigate the effect of water/benzene co-solvent vapor on the ordering of poly(styrene-b-ethylene oxide) (PS-b-PEO) copolymer thin film on silicon substrate upon solvent annealing. In-plane cylindrical PEO microdomains were observed after exposure of benzene vapor. The addition of water vapor dominantly produced the cylindrical PEO domains aligned perpendicular to the substrate. The best ordering of the cylinders was obtained at the water fraction of approximately 0.05. The degree of ordering decreases while the periodicity of haxagonally packed PEO cylinders increases with the amount of water in the vapor mixture. The average center-to-center distance of hexagonally packed cylindrical PEO microdomains increases with the water fraction from approximately 25 nm to 40 nm. As one way of utilizing the dewetting of thin films inevitable during solvent annealing, PS-b-PEO micropatterns prepared by microcontact printing were treated with co-solvent vapor, which allows us to fabricate the controlled dewet structures guided by the micropatterns. Cylinder-to-sphere phase transition of PEO microdomains also occurred upon solvent annealing in the micropatterned PS-b-PEO films.

  8. Hexagonal-to-cubic phase transformation in composite thin films induced by FePt nanoparticles located at PS/PEO interfaces.

    Science.gov (United States)

    Aissou, Karim; Fleury, Guillaume; Pecastaings, Gilles; Alnasser, Thomas; Mornet, Stéphane; Goglio, Graziella; Hadziioannou, Georges

    2011-12-06

    The organization process of asymmetric poly(styrene-block-ethylene oxide) (PS-b-PEO) copolymer thin films blended with FePt nanoparticles is studied. In a first step, it is shown that FePt nanoparticles stabilized by oleic acid ligands are distributed within the PS matrix phase, whereas the same particles partially covered with short dopamine-terminated-methoxy poly(ethylene oxide) (mPEO-Dopa) are located at PS/PEO interfaces. The swelling of PS domains, induced by FePt_oleic acid nanoparticles during the solvent annealing process, results in formation of a disordered microstructure in comparison to the well-organized hexagonally close-packed (HCP) cylinder phase formed in the neat PS-b-PEO copolymer. The evolution of the microstructure of PS-b-PEO/FePt_mPEO-Dopa composite has been investigated for different solvent annealing treatments. Under high-humidity conditions during the vapor annealing process, the addition of FePt nanoparticles results in formation of spheres in the film split into terraces. The upper and lower terraces are occupied by spheres organized in an unusual square and HCP phases, respectively. Under low-humidity conditions, undulated PEO cylinders oriented parallel to substrate are formed in the presence of FePt nanoparticles. In this case, we observe that most of the nanoparticles accumulate within the core of topological defects, which induces a low nanoparticle concentration at the PS/PEO interfaces and so stabilizes an intermediate undulated cylinder phase.

  9. Stearic acid and high molecular weight PEO as matrix for the highly water soluble metoprolol tartrate in continuous twin-screw melt granulation.

    Science.gov (United States)

    Monteyne, Tinne; Adriaensens, Peter; Brouckaert, Davinia; Remon, Jean-Paul; Vervaet, Chris; De Beer, Thomas

    2016-10-15

    Granules with release-sustaining properties were developed by twin screw hot melt granulation (HMG) using a combination of stearic acid (SA) and high molecular weight polyethylene oxide (PEO) as matrix for a highly water soluble model drug, metoprolol tartrate (MPT). Earlier studies demonstrated that mixing molten SA and PEO resulted in hydrogen bond formation between hydroxyl groups of fatty acid molecules and ether groups in PEO chains. These molecular interactions might be beneficial in order to elevate the sustained release effect of drugs from a SA/PEO matrix. This study aims to investigate the continuous twin screw melt granulation technique to study the impact of a SA/PEO matrix on the dissolution rate of a highly water soluble drug (MPT). Decreasing the SA/PEO ratio improved the release-sustaining properties of the matrix. The solid state of the granules was characterized using differential scanning calorimetry (DSC), nuclear magnetic resonance (NMR), X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR) and near infrared chemical imaging (NIR-CI) in order to understand the dissolution behavior. The results revealed a preferential interaction of the MPT molecules with stearic acid impeding the PEO to form hydrogen bonds with the stearic acid chains. However, this allowed the PEO chains to recrystallize inside the stearic acid matrix after granulation, hence, elevating the release-sustaining characteristics of the formulation.

  10. Effect of PEO-modes on the electrochemical and mechanical properties of coatings on MA8 magnesium alloy

    Science.gov (United States)

    Sidorova, M. V.; Sinebrukhov, S. L.; Khrisanfova, O. A.; Gnedenkov, S. V.

    Protective surface layers with a high corrosion stability and significant microhardness as compared to the substrate material were obtained on MA8 magnesium alloy by Plasma Electrolytic Oxidation (PEO) in a silicate-fluoride electrolyte. The phase and elemental composition of the coatings were investigated. It was found that the application of the bipolar PEO-modes enables one to synthesize on the alloy's surface a high-temperature phase of magnesium silicate, forsterite (Mg2SiO4) having a good anticorrosion and mechanical properties.

  11. Preparation of PEO/Clay Nanocomposites Using Organoclay Produced via Micellar Adsorption of CTAB

    Directory of Open Access Journals (Sweden)

    Ahmet Gürses

    2012-01-01

    Full Text Available The aim of this study was the preparation of polyethylene oxide (PEO/clay nanocomposites using organoclay produced via micellar adsorption of cethyltrimethyl ammonium bromide (CTAB and their characterisation by X-ray diffraction (XRD, and Fourier transform infrared (FT-IR spectra, and the investigation of certain mechanical properties of the composites. The results show that the basal distance between the layers increased with the increasing CTAB/clay ratio as parallel with the zeta potential values of particles. By considering the aggregation number of CTAB micelles and interlayer distances of organo-clay, it could be suggested that the predominant micelle geometry at lower CTAB/clay ratios is an ellipsoidal oblate, whereas, at higher CTAB/clay ratios, sphere-ellipsoid transition occurs. The increasing tendency of the exfoliation degree with an increase in clay content may be attributed to easier diffusion of PEO chains to interlayer regions. FT-IR spectra show that the intensity of Si-O stretching vibrations of the organoclays (1050 cm−1 increased, especially in the ratios of 1.0 g/g clay and 1.5 g/g clay with the increasing CTAB content. It was observed that the mechanical properties of the composites are dependent on both the CTAB/clay ratios and clay content of the composites.

  12. Local in vitro delivery of rapamycin from electrospun PEO/PDLLA nanofibers for glioblastoma treatment.

    Science.gov (United States)

    Wang, Benlin; Li, Haoyuan; Yao, Qingyu; Zhang, Yulin; Zhu, Xiaodong; Xia, Tongliang; Wang, Jian; Li, Gang; Li, Xingang; Ni, Shilei

    2016-10-01

    Rapamycin, a mammalian target of rapamycin inhibitor and anti-proliferative agent, is used to treat glioma and other malignancies, but its effectiveness is limited by the fact that it cannot be delivered in a targeted manner to the site of the tumor. To address this issue, we fabricated a mesh via electrospinning using two biodegradable materials, poly(lactic acid) (PLA) and polyethylene oxide (PEO) as a carrier for rapamycin delivery to the tumor. Nanofiber diameter decreased with increasing PLA concentration in the mixed solution. Scanning electron microscopy analysis revealed the smooth and uniform surface morphology of hybrid fibers. Fourier transform infrared spectroscopy analysis demonstrated that rapamycin was encapsulated in the polymer solution; encapsulation efficiency was high and stable over the range of drug concentrations from 0.5-2wt%. A correlation was observed between sustained release of the drug in vitro and cytotoxicity in cultured glioma cells. These results indicate that the PEO/poly(d,l-lactic acid) nanofiber mesh can be used as a targeted delivery system for rapamycin that can limit side effects and prevent locoregional recurrence following surgical resection of glioma.

  13. Effect of nanocrystalline surface of substrate on microstructure and wetting of PEO coatings

    Indian Academy of Sciences (India)

    H R Masiha; H R Bagheri; M Gheytani; M Aliofkhazraei; A Sabour Rouhaghdam; T Shahrabi

    2015-08-01

    In this research, effect of surface mechanical attrition treatment (SMAT) was studied on characteristics of the coatings formed using plasma electrolyte oxidation (PEO) on AA1230 aluminium. To do so, first, the samples were coated with and without SMAT pre-process. Coating by PEO method was carried out in two phosphate-based and silicate-based suspensions of silicon nitride nanoparticles for 10 min. Next, to study the distribution of the nanoparticles and elements inside the coating, surface morphology of the samples was examined using scanning electron microscopy and energy dispersive spectroscopy. In addition, wettability test was performed on all samples using the deionized water. Also, droplet expansion manner on the porous oxide coating surface and its relation with fine structure of the coating was investigated. The results indicated that samples coated in silicate-based electrolyte have a relatively rougher microstructure as compared to samples coated in phosphate-based electrolyte. The average surface pores area percentage of the samples coated in silicate-based electrolytes was 13.9% greater than that of samples coated in phosphate-based electrolyte. Moreover, the average height to diameter (h/d) value obtained from wettability test for samples coated in silicate-based electrolyte was 13.3% greater than that of phosphate-based electrolyte.

  14. Thermal Spectroscopy and Kinetic Studies of PEO/PVDF Loaded by Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Laila Hussein Gaabour

    2015-01-01

    Full Text Available Nanocomposites of polyethylene oxide (PEO and polyvinylidene fluoride (PVDF without and with low content of single and multiwalled carbon nanotubes (SWCNTs-MWCNTs were prepared and studied by thermogravimetric analysis (TGA using different heating rate. TGA results indicate that the thermal stability of neat PEO/PVDF blend was improved with both heating rate and incorporation of carbon nanotubes (CNTs. The degradation temperature for neat blend was lower than those of the nanocomposites after adding both SWCNTs and MWCNTs. As increase of heating rate, the onset of decomposition is irregularly moved to higher temperatures. This indicates that the thermal stability of the polymeric matrices has been improved after addition of CNTs. The residual weight of the samples left increased steadily with adding of both SWCNTs and MWCNTs. Kinetic thermodynamic parameters such as activation energy, enthalpy, entropy, and Gibbs free energy are evaluated from TGA data using Coats-Redfern model. The values of all parameters irregularly decrease with increasing of heating rate due to increasing of heating rate temperature, the random scission of macromolecule chain in the polymeric matrices predominates and the activation energy has a lower value.

  15. Preparation and study of conductivity in lithium salt complexes of mixed MEEP : PEO polymer electrolytes

    Indian Academy of Sciences (India)

    G Saibaba; D Srikanth; A Ramachandra Reddy

    2004-02-01

    Poly(ethylene oxide)–LiX complexes and poly[bis(methoxy ethoxy ethoxide) phosphazene]–LiX complexes of polymer thin films were prepared. Conductivity measurements were carried out and the values were found to lie between 10-8 and 1.7 × 10-5 (S/cm). MEEP : LiX salts showed higher conductivity than PEO–LiX salts despite lower dimensional stability. For enhancing stability and conductivity, MEEP–PEO : (LiX) systems were prepared and conductivity measurements carried out. Further the MEEP/PEO : (LiX) was doped with Al2O3 and TiO2 nanocomposite ceramic fillers and the conductivity was studied. The conductivity vs temperature plots showed the enhancement of conductivity with TiO2 added nanocomposite ceramic fillers. The enhanced conductivity is explained on the basis of the effect of local structural modification-promoting localized amorphous region-for enhancement of the Li+ ion transport.

  16. Systematic study of the structure of alternate pyromellitimide-PEO copolymers: Influence of the chain flexibility

    Energy Technology Data Exchange (ETDEWEB)

    Djurado, David [Laboratoire d' Electronique Moleculaire Organique and Hybride, DRFMC/SPrAM/CEA Grenoble, UMR CEA-CNRS-UJF 5819, 17 Avenue des Martyrs, 38054 Grenoble Cedex 9 (France); Curtet, Jean Pierre; Bee, Marc [Laboratoire de Spectrometrie Physique (UMR CNRS-UJF-5588) Universite J. Fourier, Grenoble I, Domaine Universitaire, B.P. 87 38402 St Martin d' Heres Cedex (France); Michot, Christophe [Department of Chemistry, University of Montreal, C.P. 6128, Succursale Centre-Ville, Montreal, Quebec H3C JJ7 (Canada); Armand, Michel [Department of Chemistry, University of Montreal, C.P. 6128, Succursale Centre-Ville, Montreal, Quebec H3C JJ7 (Canada); Laboratoire de Reactivite et de Chimie des Solides, Universite de Picardie Jules Verne, UMR 6007 CNRS, 33 rue Saint-Leu, 80039 Amiens (France)

    2007-12-31

    The structure of a family of copolyimides in which are alternating stiff/redox pyromellitimide units and flexible/solvating polyethyleneoxide (PEO) strands were studied by using wide angle and small angle X-ray scattering techniques and is fully discussed. It is shown that the rich variety of structures exhibited by these compounds can be understood by considering the dramatic change of flexibility of the chain induced by the variation of the length of the PEO strand compared to that of the pyromellimide segment. In this respect, concerning the compounds which exhibit fully amorphous structures a better understanding of their structural behavior can be obtained in the framework of Flory's theory of semi-rigid polymers. In this approach, the degree of flexibility of the chain is mainly resulting from the relative amount of flexible units constituting the repetition unit of the polymer chain. The final structural mode adopted by each compound in the solid state is then directly a consequence of this intrinsic property of the chain. The introduction of a lithium salt in contact with the copolymer chains induces some structure changes which can also be explained by the modification of the degree of flexibility of the chain. It is found that the best performances in terms of electroactivity and mixed conduction are precisely obtained with the only compound which keeps full amorphicity in absence and in presence of the lithium salt. (author)

  17. PEE-PEO block copolymer exchange rate between micelles is detergent and temperature activated

    Science.gov (United States)

    Schantz, Allen; Saboe, Patrick; Lee, Hee-Young; Sines, Ian; Butler, Paul; Bishop, Kyle; Maranas, Janna; Kumar, Manish

    We examine the kinetics of polymer chain exchange between polymer/detergent micelles, a system relevant to the synthesis of protein-containing biomimetic membranes. Although chain exchange between polymer aggregates in water is too slow to observe, adding detergent allows us to determine chain exchange rates using time-resolved small-angle neutron scattering (TR-SANS). We examine a membrane-protein-relevant, vesicle-forming ultra-short polymer, Poly(ethyl ethylene)20-Poly(ethylene oxide)18 (PEE20-PEO18). PEE20-PEO18 is solubilized in mixed micelles with the membrane-protein-compatible non-ionic detergent octyl- β -D-glucoside (OG). We show that OG activates block copolymer exchange, and obtain rate constants at two detergent concentrations above the CMC (critical micellar concentration) of OG. We find that chain exchange increases two orders of magnitude when temperature increases from 308 to 338 K, and that even a 1 mg/mL increase in OG concentration leads to a noticeable increase in exchange rate. We also calculate the activation energy for chain exchange and find that it is much higher than for lipid exchange. These findings explain the need for high detergent concentration and/or temperature to synthesize densely packed polymer/protein membranes.

  18. Coating of poly(p-xylylene) by PLA-PEO-PLA triblock copolymers with excellent polymer-polymer adhesion for stent applications.

    Science.gov (United States)

    Hanefeld, Phillip; Westedt, Ullrich; Wombacher, Ralf; Kissel, Thomas; Schaper, Andreas; Wendorff, Joachim H; Greiner, Andreas

    2006-07-01

    Poly(p-xylylene) (PPX) was deposited by chemical vapor deposition (CVD) on stainless steel substrates. These PPX films were coated by solution casting of poly(lactide)-poly(ethylene oxide)-poly(lactide) triblock copolymers (PLA-PEO-PLA) loaded with 14C-labeled paclitaxel. Adhesion of PLA-PEO-PLA on PPX substrate coatings was measured using the blister test method. Excellent adhesion of the block copolymers on PPX substrates was found. Stress behavior and film integrity of PLA-PEO-PLA was compared to pure PLA on unexpanded and expanded stent bodies and was found to be superior for the block copolymers. The release of paclitaxel from the biodegradable coatings was studied under physiological conditions using the scintillation counter method. Burst release of paclitaxel was observed from PLA-PEO-PLA layers regardless of composition, but an increase in paclitaxel loading was observed with increasing content of PEO.

  19. External Otitis (Swimmer's Ear)

    Science.gov (United States)

    ... to Pneumococcal Vaccine Additional Content Medical News External Otitis (Swimmer's Ear) By Bradley W. Kesser, MD, Associate ... the Outer Ear Ear Blockages Ear Tumors External Otitis (Swimmer's Ear) Malignant External Otitis Perichondritis External otitis ...

  20. Preparation and Properties of PVA/PEO/MWCNTs Ultra-fine Fiber by Electrospinning%静电纺PVA/PEO/多壁碳纳米管超细纤维的制备与性能

    Institute of Scientific and Technical Information of China (English)

    张凯莉; 戴晋明; 侯文生; 范海宾; 相增辉; 罗秋兰

    2011-01-01

    In this paper, the polyvinyl alcohol/multi-walled carbon nanotubes (PVA/MWCNTs) complex solution was prepared by ultrasonic solution mixing methods, then this solution was mixed with polyethylene oxide (PEO), and the PVA/PEO/MWCNTs/ultra-fine composite fiber was obtained through electrospinning technique. The microstructure and heat properties of samples with different contents of MWCNTs were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimeter (DSC). The results indicated that the diameter of fiber got markedly thinner with increase of MWCNTs, the crystallinity of fiber reduced because of addition of MWCNTs. Furthermore, the thermal stability of composite fiber had improved some.%采用超声波辅助溶液共混的方式制备聚乙烯醇/多壁碳纳米管(PVA/MWCNT)复合溶液,并将该溶液与聚氧化乙烯(PEO)溶液共混,利用静电纺丝技术制备PVA/PEO/MWCNTs复合超细纤维.运用扫描电子显微镜(SEM)、X-射线衍射仪(XRD)、示差扫描量热仪(DSC)方法对不同MWCNTs含量的PVA/PEO/MWCNTs复合纤维的微观形貌、结构和热性能进行了观察分析.结果表明:随着MWCNTs含量的增加,纤维直径显著变细,MWCNTs的加入降低了纤维的结晶性,纤维的热稳定性有所提高.

  1. A Facile Method to Form a Densely Grafted PEO-b-P4VP Brush on Gold Surface

    Institute of Scientific and Technical Information of China (English)

    杨倩; 周常明; 陈旺; 方佳节; 陈道勇

    2012-01-01

    Here we report a facile method for the preparation of a PEO113-b-P4VP93 brush on gold surface with a grafting density as high as 1.32 chains/nm2; the P4VP blocks were physically adsorbed on gold surface forming an inner layer while the PEO blocks stretched towards the solution forming PEO brush. PEOl13-b-P4VPq3 micelles with P4VP core and PEO shell formed in methanol/water mixed solvents were used as the precursor. By adsorbing PEOII3-b-P4VP93 micelles from pure water, in which the density of the micelles is the largest, maximum amount of the micelles was adsorbed onto gold surface, and the adsorbed micelles existed as individual domains on the surface To prepare the polymer brush with a density as high as possible, we annealed the adsorbed micelles by metha- nol/water mixed solvent at the volume fraction of methanol (VF) of 20%, which was the proper proportion at which the core-forming P4VP chains began to be flexible but the integrity of the micelles was remained. At this volume fraction, almost all the adsorbed micelles originally existing as individual domains were transformed into a dense polymer brush.

  2. Dexamethasone loaded core-shell SF/PEO nanofibers via green electrospinning reduced endothelial cells inflammatory damage.

    Science.gov (United States)

    Chen, Weiming; Li, Dawei; Ei-Shanshory, Ahmed; El-Newehy, Mohamed; Ei-Hamshary, Hany A; Al-Deyab, Salem S; He, Chuanglong; Mo, Xiumei

    2015-02-01

    Silk fibroin (SF)/PEO nanofibers prepared by green electrospinning is safe, non-toxic and environment friendly, it is a potential drug delivery carrier for tissue engineering. In this study, a core-shell nanofibers named as Dex@SF/PEO were obtained by green electrospinning with SF/PEO as the shell and dexamethasone (Dex) in the core. The nanofiber morphology and core-shell structure were studied by Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). The Dex release behavior from the nanofibers was tested by High Performance liquid (HPLC) method. The protective effect of drug loaded nanofibers mats on Porcine hip artery endothelial cells (PIECs) against LPS-induced inflammatory damage were determined by MTT assay. TEM result showed the distinct core-shell structure of nanofibers. In vitro drug release studies demonstrated that dexamethasone can sustain release over 192 h and core-shell nanofibers showed more slow release of Dex compared with the blending electrospinning nanofibers. Anti-inflammatory activity in vitro showed that released Dex can reduce the PIECs inflammatory damage and apoptosis which induced by lipopolysaccharide (LPS). Dex@SF/PEO nanofibers are safe and non-toxic because of no harmful organic solvents used in the preparation, it is a promising environment friendly drug carrier for tissue engineering.

  3. Interactions of Pluronic nanocarriers with 2D and 3D cell cultures: Effects of PEO block length and aggregation state.

    Science.gov (United States)

    Arranja, Alexandra; Denkova, Antonia G; Morawska, Karolina; Waton, Gilles; van Vlierberghe, Sandra; Dubruel, Peter; Schosseler, François; Mendes, Eduardo

    2016-02-28

    This work reveals how the physicochemical properties of Pluronic block copolymers influence significantly their interactions with cancer cells, whether in monolayer or spheroid cultures, and how different clinical applications can be foreseen. Two-dimensional (2D) and three-dimensional (3D) cell culture models were used to investigate the interactions of Pluronic carriers with different PEO block length and aggregation state (unimers versus cross-linked micelles) in HeLa and U87 cancer cells. Stabilized micelles of Pluronic P94 or F127 were obtained by polymerization of a crosslinking agent in the micelles hydrophobic core. Nanocarriers were functionalized with a fluorescent probe for visualization, and with a chelator for radiolabeling with Indium-111 and gamma-quantification. The 2D cell models revealed that the internalization pathways and ultimate cellular localization of the Pluronic nanocarriers depended largely on both the PEO block size and aggregation state of the copolymers. The smaller P94 unimers with an average radius of 2.1nm and the shortest PEO block mass (1100gmol(-1)) displayed the highest cellular uptake and retention. 3D tumor spheroids were used to assess the penetration capacity and toxicity potential of the nanocarriers. Results showed that cross-linked F127 micelles were more efficiently delivered across the tumor spheroids, and the penetration depth depends mostly on the transcellular transport of the carriers. The Pluronic P94-based carriers with the shortest PEO block length induced spheroid toxicity, which was significantly influenced by the spheroid cellular type.

  4. Interactions of Apolipoproteins AI, AII, B and HDL, LDL, VLDL with Polyurethane and Polyurethane-PEO Surfaces.

    Science.gov (United States)

    Cornelius, R M; Macri, J; Cornelius, K M; Brash, J L

    2015-11-10

    The lipoproteins (HDL, LDL, VLDL) are important components of blood present in high concentration. Surprisingly, their role in blood-biomaterial interactions has been largely ignored. In previous work apolipoprotein AI (the main protein component of HDL) was identified as a major constituent of protein layers adsorbed from plasma to biomaterials having a wide range of surface properties, and quantitative data on the adsorption of apo AI to a biomedical grade polyurethane were reported. In the present communication quantitative data on the adsorption of apo AI, apo AII and apoB (the latter being a constituent of LDL and VLDL), as well as the lipoprotein particles themselves (HDL, LDL, VLDL), to a biomedical segmented polyurethane (PU) with and without an additive containing poly(ethylene oxide) (material referred to as PEO) are reported. Using radiolabeled apo AI, apo AII, and apoB, adsorption levels on PU from buffer at a protein concentration of 50 μg/mL were found to be 0.34, 0.40, and 0.14 μg/cm(2) (12, 23, and 0.25 nmol/cm(2)) respectively. Adsorption to the PEO surface was PEO as well as to the PU surface. X-ray photoelectron spectra, following exposure of the surfaces to the lipoproteins, showed a strong phosphorus signal, confirming that adsorption had occurred. It therefore appears that a PEO-containing surface that is resistant to apolipoproteins may be less resistant to the corresponding lipoproteins.

  5. Optimization of hybrid polymer electrolytes with the effect of lithium salt concentration in PEO/PVdF-HFP blends

    Energy Technology Data Exchange (ETDEWEB)

    Pradeepa, P.; Edwin raj, S.; Sowmya, G.; Kalaiselvimary, J.; Ramesh Prabhu, M., E-mail: mkram83@gmail.com

    2016-03-15

    Highlights: • Polymer blends based on PVdF-HFP/PEO were prepared for Li-ion battery applications. • Structural and electrochemical studies were carried out on prepared electrolytes. • The electrolytes can be used as electrolyte in the possible device fabrications. - Abstract: Poly(ethylene oxide) (PEO) 6.25 wt%/poly(vinylidene fluoride-co-hexafluoropropylene) [P(VdF-HFP)] 18.75 wt% blend based electrolyte films containing different concentrations (2–10) wt% of lithium salt were prepared. The miscibility studies have been performed by using X-ray diffraction and Fourier transform infrared spectroscopy. The role of interaction between polymer hosts on conductivity is discussed using the results of a.c. impedance studies. A room temperature conductivity of 2.3912 × 10{sup −4} S cm{sup −1} has been obtained for PEO (6.25)–PVdF-HFP (18.75)–LiClO{sub 4} (8)–PC (67) polymer complex. The temperature dependence of the conductivity of polymer electrolyte seems to obey VTF relation. Electrochemical stability (3.3 V) was observed in the prepared polymer electrolyte. Reduction process and oxidation process of the prepared electrolyte system have also been evaluated by means of cyclic voltammetry. Thermogravimetric analysis results indicate thermal stability of PEO/PVdF-HFP lithium salt complexes. Roughness parameter of the sample having maximum ionic conductivity was studied by AFM. The morphology of the polymer complex is investigated by using SEM.

  6. Thermal, Mechanical and Electrical Properties of the PEO-based Solid Polymer Electrolytes Filled by Yttrium Oxide Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    LIANG Guijie; XU Jie; XU Weilin; SHEN Xiaolin; BAI Zhikui; YAO Mu

    2012-01-01

    The novel composite lithium solid polymer electrolytes (SPEs) composed of polyethylene oxide (PEO) matrix and yttrium oxide (Y2O3) nanofillers were prepared by a solution casting method.The crystal morphology of the SPEs was characterized by polarized optical microscope (POM) and wide-angle X-ray diffraction (WAXD).The induced nucleation and steric hindrance effects of Y203 nanofillers result in the increased amount as well as decreased size of PEO sphemlites which are closely related to the crystallinity of the SPEs.As the Y2O3 contents increase from 0 wt% to 15 wt,the crystallinity of the SPEs decreases proportionally.The thermal,mechanical and electrical properties of the SPEs were investigated by thermal gravimetric analysis (TGA),dynamic mechanical analysis (DMA) and AC impedance method,respectively.The physical properties including thermal,mechanical and electrical performances,depending remarkably on the polymer-filler interactions between PEO and Y2O3 nanoparticles,are improved by different degrees with the increase of Y2O3 contents.The (PEO)21Lii/10 wt%Y2O3 composite SPE exhibits the optimal room-temperature ionic conductivity of 5.95×10-5 S*cm-1,which satisfies the requirements of the conventional electrochromic devices..

  7. Structure and ionic conductivity of ionic liquid embedded PEO- LiCF3SO3 polymer electrolyte

    Directory of Open Access Journals (Sweden)

    A. Karmakar

    2014-08-01

    Full Text Available In this paper we have reported electrical and other physical properties of polyethylene oxide (PEO - LiCF3SO3 polymer electrolytes embedded with 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ionic liquid. The addition of the ionic liquid to PEO- LiCF3SO3 electrolyte increases the amorphous phase content considerably and decreases the glass transition temperature. The relative amounts of different ionic species present in these electrolytes have been determined. It is observed that the fraction of free anions increase with the increase of ionic liquid concentration, whereas the fraction for ion pairs and aggregates show a decreasing trend under the same condition. The ionic conductivity of the PEO- LiCF3SO3 polymer electrolyte embedded with ionic liquid is higher than that of the PEO- LiCF3SO3 electrolyte. The ionic conductivity shows a transition around 323 K. The ionic conductivity above 323 K exhibits Arrhenius behavior with an activation energy, which decreases with the increase of ionic liquid concentration. However, below 323 K the conductivity shows Vogel–Tamman–Fulcher (VTF type behavior.

  8. The Production of PEO Polymer Brushes via Langmuir-Blodgett and Langmuir-Schaeffer Methods: Incomplete Transfer and Its Consequences

    NARCIS (Netherlands)

    Vos, de W.M.; Keizer, de A.; Kleijn, J.M.; Cohen Stuart, M.A.

    2009-01-01

    Using fixed-angle ellipsometry, we investigate the degree of mass transfer upon vertically dipping a polystyrene surface through a layer of a polystyrene-poly(ethylene oxide) (PS-PEO) block copolymer at the air water interface (Langmuir-Blodgett or LB transfer). The transferred mass is proportional

  9. Mussel-inspired functionalization of PEO/PCL composite coating on a biodegradable AZ31 magnesium alloy.

    Science.gov (United States)

    Tian, Peng; Xu, Demin; Liu, Xuanyong

    2016-05-01

    The rapid degradation of magnesium-based implants in physiological environments in vivo not only will quickly deteriorate their mechanical strengths but will also lead to a severe change of the micro-environment around the implants, which may cause the final failure of magnesium-based implants. In this work, a polycaprolactone (PCL) layer was prepared to seal the plasma electrolytic oxidization coating (PEO) to form a PEO/PCL composite coating on a biodegradable AZ31 magnesium alloy, followed by further surface functionalization with polydopamine. The in vitro degradation behaviors of the bare AZ31 alloy and coated samples were evaluated in a simulated body fluid (SBF) using the potentiodynamic polarization curve test and the static immersion test. The bioactivity of the samples was investigated using the SBF soaking test. The cytocompatibility of all samples was evaluated using the cytotoxicity test and analysis of the adhesion and proliferation of osteoblast cells (MC3T3-E1) directly cultivated on the sample surface. The results showed that the PCL layer successfully sealed the pores of the PEO coating, and then the polydopamine layer formed on its surface. The in vitro degradation tests showed that the PEO/PCL composite coating improved the corrosion resistance of the AZ31 alloy in SBF with a more positive corrosion potential and a lower corrosion current density. Due to the protection of the PEO/PCL composite coating, the surrounding environment showed nearly no influence on the degradation of the coated sample, which led to no obvious local alkalization and hydrogen evolution. Moreover, compared with the AZ31 alloy and PEO coating, the PEO/PCL composite coating was more suitable for cell adhesion and proliferation. After further surface functionalization by polydopamine, the corrosion resistance of the composite coating was maintained, while its bioactivity was significantly enhanced with a large amount of hydroxyapatite (HA) formed on its surface after

  10. Investigations on Poly (ethylene oxide) (PEO) - blend based solid polymer electrolytes for sodium ion batteries

    Science.gov (United States)

    Koduru, H. K.; Iliev, M. T.; Kondamareddy, K. K.; Karashanova, D.; Vlakhov, T.; Zhao, X.-Z.; Scaramuzza, N.

    2016-10-01

    Polymer blend electrolytes based on Polyethylene oxide (PEO) and polyvinyl pyrrolidone (PVP), complexed with NaIO4 salt and Graphene oxide (GO) are investigated in the present report. The electrolytes are prepared by a facile solution cast technique. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) are employed to study the influence of ion-polymer interactions on the micro structural properties of blend electrolytes. Measurements of electrical conductivity of the blend polymer complexes have been performed by using complex impedance spectroscopy in the frequency range 1 Hz - 1 MHz and within the temperature range 303 K - 343 K.A study on electrical conductivity properties of GO doped ‘salt complexed electrolyte’ systems is presented.

  11. Photocured PEO-based solid polymer electrolyte and its application to lithium-polymer batteries

    Science.gov (United States)

    Kang, Yongku; Kim, Hee Jung; Kim, Eunkyoung; Oh, Bookeun; Cho, Jae Hyun

    A solid polymer electrolyte (SPE) based on polyethylene oxide (PEO) is prepared by photocuring of polyethylene glycol acrylates. The conductivity is greatly enhanced by adding low molecular weight poly(ethylene glycol) dimethylether (PEGDME). The maximum conducticity is 5.1×10 -4 S cm -1 at 30°C. These electrolytes display oxidation stability up to 4.5 V against a lithium reference electrode. Reversible electrochemical plating/stripping of lithium is observed on a stainless steel electrode. Li/SPE/LiMn 2O 4 as well as C(Li)/SPE/LiCoO 2 cells have been fabricated and tested to demonstrate the applicability of the resulting polymer electrolytes in lithium-polymer batteries.

  12. Effects of tensile strain on the peculiarities of PEO penetration into the nanoporous structure of PET deformed via the crazing mechanism.

    Science.gov (United States)

    Rukhlya, E G; Yarysheva, L M; Volynskii, A L; Bakeev, N F

    2016-04-14

    Solvent crazing involves the development of a highly dispersed fibrillar-porous structure with dimensions of pores and craze fibrils of about 2-20 nm, and crazing by itself can be treated as a universal method for the development of nanoscale porosity. The penetration and release of poly(ethylene oxide) macromolecules into and from the crazes during the development of the nanoporous structure of poly(ethylene terephthalate) have been studied. In particular, PET has been deformed in dilute or semidilute (unentangled as well as entangled) solutions of PEO (a Mw of 4 and 40 kDa) via the mechanism of solvent crazing. Hydrodynamic coil radii Rh, blob sizes ξ, and concentration ranges (crossover and entanglement concentrations) have been determined for the PEO solutions. The evolution of the craze structure (change in porosity W and pore diameters d) has been described as a function of the tensile strain of PET during its drawing in an adsorption-active medium and in the PEO solutions. PEO has been shown to penetrate into the nanoporous structure of the crazes under the conditions corresponding to Rh≤d and ξ PEO adsorption at the highly developed surface of PET, and the mechanism of PEO transport in the nanopores are equally important factors affecting the direction of the macromolecule mass transfer in the nanopores (penetration or release) and PEO content variation as a function of PET tensile strain.

  13. Preparation and characterization of V-shaped PS-b-PEO brushes anchored on planar gold substrate through the trithiocarbonate junction group.

    Science.gov (United States)

    Wang, Zhao-Li; Xu, Jun-Ting; Du, Bin-Yang; Fan, Zhi-Qiang

    2012-10-15

    Trithiocarbonate group was introduced into the polystyrene-b-poly(ethylene oxide) (PS-b-PEO) block copolymers as the junction of the blocks through RAFT polymerization. Mixed PS and PEO brushes with a V-shape were prepared by anchoring the trithiocarbonate group on the planar gold substrate. The morphology of the V-shaped brushes was characterized by atomic force microscopy (AFM) and the surface composition responsive to solvent treatment was detected by X-ray photoelectron spectroscopy (XPS). Different morphologies were observed for the V-shaped PS-b-PEO brushes, depending on the chain structure and solvent treatment. The highly selective solvent for PEO, ethanol, can intensify or induce microphase separation of the V-shaped brushes, leading to vertical microphase separation. When the V-shaped brushes are treated with the co-solvent, THF, miscible morphology, lateral microphase separation, and vertical microphase separation are observed as the PS block length increases. After treatment with the non-selective poor solvent, cyclohexane, the V-shaped PS(106)-b-PEO(113) brush, exhibits a laterally microphase-separated morphology, but the V-shaped PS(52)-b-PEO(113) and PS(253)-b-PEO(113) brushes are vertically microphase-separated.

  14. The Study of Morphological Structure, Phase Structure and Molecular Structure of Collagen-PEO 600K Blends for Tissue Engineering Application

    Directory of Open Access Journals (Sweden)

    N. F. Mohd Nasir

    2006-01-01

    Full Text Available A new material which is collagen/ poly (ethylene oxide (PEO blend was developed to determine its possibility as a promising material for tissue scaffold. PEO with average molecular weight of 600,000 and collagen originated from calf skin were dispersed in 0.1 M acetic acid to prepare a concentration of 1 wt% for PEO and 0.15 wt% for collagen. The collagen-PEO600K blend film was then obtained by solution casting method. SEM results shown that by having certain ratio of collagen and PEO, the membrane began to developed porous structures which are possible to assist tissue attachment on the scaffold. The X-ray diffractograms demonstrate PEO 600K influences on the blend thus enhancing crystallinity of collagen. The Infra red spectrum shows intermolecular interactions of collagen and PEO which alter the collagen structure thus explained the membrane morphological changes. Therefore, we concluded that the phase structure and also the molecular structure of the blend are crucial to produce desirable morphological structure of the membrane which is required for a reliable tissue scaffold.

  15. PLGA implants: How Poloxamer/PEO addition slows down or accelerates polymer degradation and drug release.

    Science.gov (United States)

    Hamoudi-Ben Yelles, M C; Tran Tan, V; Danede, F; Willart, J F; Siepmann, J

    2017-03-08

    The aim of this study was to evaluate the impact of the addition of small amounts of hydrophilic polymers (Poloxamer 188 and PEO 200kDa) to PLGA-based implants loaded with prilocaine. Special emphasis was placed on the importance of the type of preparation technique: direct compression of milled drug-polymer powder blends versus compression of drug loaded microparticles (prepared by spray-drying). The implants were thoroughly characterized before and upon exposure to phosphate buffer pH7.4, e.g. using optical and scanning electron microscopy, X-ray diffraction, DSC and GPC. Interestingly, the addition of Poloxamer/PEO to the PLGA implants had opposite effects on the resulting drug release kinetics, depending on the type of preparation method: in the case of implants prepared by compression of milled drug-polymer powder blends, drug release was accelerated, whereas it was slowed down when the implants were prepared by compression of drug loaded PLGA microparticles. These phenomena could be explained by the swelling/disintegration behavior of the implants upon exposure to the release medium. Systems consisting of compressed microparticles remained intact and autocatalytic effects were of major importance. The presence of a hydrophilic polymer facilitated water penetration into these devices, slowing down PLGA degradation and drug release. In contrast, implants consisting of compressed drug-polymer powder blends rapidly (at least partially) disintegrated and autocatalysis was much less important. In these cases, the addition of a hydrophilic polymer facilitated ester bond cleavage, leading to accelerated PLGA degradation and drug release.

  16. Theoretical Predictions of Temperature-Induced Gelation in Aqueous Dispersions Containing PEO-Grafted Particles.

    Science.gov (United States)

    Xie, Fei; Woodward, Clifford E; Forsman, Jan

    2016-04-28

    In this work, we utilize classical polymer density functional theory (DFT) to study gelation in systems containing colloidal particles onto which polymers are grafted. The solution conditions are such that the corresponding bulk system displays a lower critical solution temperature (LCST). We specifically compare our predictions with experimental results by Shay et al. (J. Rheol. 2001, 45, 913-927), who investigated temperature response in aqueous dispersions containing polystyrene particles (PS), with grafted 45-mer poly(ethylene oxide) (PEO) chains. Our DFT treatment is based on a model for aqueous PEO solutions that was originally developed by Karlström for bulk solutions. In this model, monomers are assumed to be in either of two classes of states, labeled A and B, where B is more solvophobic than A. On the other hand, the degeneracy of B exceeds that of A, causing the population of solvophobic monomers to increase with temperature. In agreement with experimental findings by Shay et al., we locate gelation at temperatures considerably below TΘ, and far below the LCST for such chain lengths. This gelation occurs also without any dispersion interactions between the PS particles. Interestingly, the polymer-induced interaction free energy displays a nonmonotonic dependence on the grafting density. At high grafting densities, bridging attractions between grafted layers take place (considerably below TΘ). At low grafting densities, on the other hand, the polymers are able to bridge across to the other particle surface. Shay et al. conducted their experiments at very low ionic strength, using deionized water as a solvent. We demonstrate that even minute amounts of adsorbed charge on the surface of the particles, can lead to dramatic changes of the gelation temperature, especially at high grafting densities. Another interesting prediction is the existence of elongated (chainlike) equilibrium structures, at low particle concentrations. We emphasize that our model

  17. Co-spinning of Silver Nanoparticles with Nisin Increases the Antimicrobial Spectrum of PDLLA: PEO Nanofibers.

    Science.gov (United States)

    Ahire, Jayesh J; Neveling, Deon P; Dicks, Leon M T

    2015-07-01

    Silver nanoparticles (AgNPs), synthesized using N,N-dimethylformamide (DMF), were electrospun with nisin in a 50:50 blend of 24 % (w/v) poly(D,L-lactide) (PDLLA) and poly(ethylene oxide) (PEO). Addition of AgNPs decreased the average diameter of the nanofibers [silver nanofibers (SF)] from 588 ± 191 to 281 ± 64 nm, or to 288 ± 63 nm when nisin was co-spun with AgNPs. Nanofibers containing AgNO3 (SF) had a beads-on-string structure, whereas nanofibers with AgNPs and nisin [silver plus nisin nanofibers (SNF)], nanofibers with only nisin [nisin nanofibers (NF)], and nanofibers without AgNPs and nisin [control nanofibers] had a uniform structure. The irregular topography was confirmed by atomic force microscopy. No interactions occurred between silver, nisin, PDLLA, and PEO, as confirmed with Fourier transform infrared spectroscopy. Most of the AgNPs (18 ± 2.8 ppm) and nisin (78.1 ± 1.2 µg/ml) were released within the first 2 h. SF and SNF inhibited the growth of gram-positive and gram-negative bacteria, whereas NF failed to inhibit gram-negative bacteria. A wound dressing with broad-spectrum antimicrobial activity may be developed by the incorporation of nanofibers containing a combination of AgNPs and nisin.

  18. Structure of PEP-PEO block copolymer micelles: Exploiting the complementarity of small-angle X-ray scattering and static light scattering

    DEFF Research Database (Denmark)

    Jensen, Grethe Vestergaard; Shi, Qing; Hernansanz, María J.

    2011-01-01

    . The present work shows that the same information can be obtained by combining static light scattering (SLS) and small-angle X-ray scattering (SAXS), which provide information on, respectively, large and short length scales. Micelles of a series of block copolymers of poly(ethylene propylene)-b-poly(ethylene...... oxide) (PEP-PEO) in a 70% ethanol solution are investigated. The polymers have identical PEP blocks of 5.0 kDa and varying PEO blocks of 2.8-49 kDa. The SLS contrasts of PEP and PEO are similar, providing a homogeneous contrast, making SLS ideal for determining the overall micelle morphology. The SAXS...

  19. ANTI-ELECTROLYTIC PROPERTIES OF PAA-PEO-α-Al2O3-H2O SUSPENSIONS%PAA-PEO-α-Al2O3-H2O悬浮液的抗电解质性能

    Institute of Scientific and Technical Information of China (English)

    张浩; 王晓莉; 郭露村

    2007-01-01

    The electrolytic effect on the rheological properties of a poly (acrylic acid) (PAA)-α-Al2O3-H2O suspension and the anti-electrolytic capability of a PAA-poly (ethylene oxide) (PEO)-α-Al2O3-H2O suspension were studied. The results show that the addition of an electrolyte (like NaCl or CaCl2) dramatically decreases the stability of PAA-α-Al2O3-H2O suspensions, and the influence of divalent ions (Ca2+) was more pronounced than that of univalent ions (Na+). The PAA-PEO-α-Al2O3-H2O systems can maintain inherent rheological properties in the presence of the electrolyte at same electrolytic concentrations. This behavior is attributed to the effective anti-electrolytic capability of PAA-PEO-α-Al2O3-H2O suspensions.%研究了电解质对聚丙烯酸[poly(acrylic acid),PAA]-α-Al2O3-H2O悬浮液流变性能的影响以及PAA-聚氧化乙烯[poly(ethylene oxide),PEO]-α-Al2O3-H2O悬浮液的抗电解质的性能.结果表明:PAA-α-Al2O3-H2O悬浮液的流变性能受NaCl和CaCl2等电解质的影响较大,并且二价盐CaCl2比一价盐NaCl对PAA-α-Al2O3悬浮液分散和稳定性的影响更明显,电解质造成Al2O3颗粒的絮凝,使浆料的稳定性能变差.在电解质浓度相同的条件下,PAA-PEO-α-Al2O3-H2O悬浮液基本不受电解质的影响,浆料始终保持稳定,PAA-PEO-α-Al2O3-H2O悬浮液具有很强的抗电解质能力.

  20. Study of the interface solid/solutions containing PEO-PPO block copolymers and asphaltenes by FTIR/ATR; Estudo de solucoes de copolimeros em bloco de PEO-PPO contendo asfaltenos por FTIR/DTA

    Energy Technology Data Exchange (ETDEWEB)

    Aguiar, Janaina I.S.; Neto, Jessica S.G.; Mansur, Claudia R.E. [Universidade Federal do Rio de Janeiro, Instituto de Macromoleculas, Laboratorio de Macromoleculas e Coloides na Industria de Petroleo, Rio de Janeiro, RJ (Brazil)], E-mails: janaina_333@hotmail.com, kinha_dac_dm@hotmail.com; celias@ima.ufrj.br

    2011-07-01

    The formation of water/oil emulsions can cause problems in various stages of production, processing and refining of petroleum. In this study, the technique of Fourier transform infrared spectroscopy (FTIR) using the method of attenuated total reflectance (ATR) was applied to study the solid-solutions of block copolymers based on poly(ethylene oxide)-poly(propylene oxide) (PEO-PPO) interface and its interaction in this interface with asphaltenic fractions of petroleum. The solid is the crystal of the ATR. Initially, we determined the critical micelle concentration values of the copolymers, which were consistent those obtained by a tensiometer. Bottle Test was also performed to correlate the efficiency of PEO-PPO copolymers in the breaking of water/oil emulsions with its adsorption at the interfaces solutions. (author)

  1. A mechanistic study explaining the synergistic viscosity increase obtained from polyethylene oxide (PEO) and {beta}-naphthalene sulfonate (BNS) in shotcrete

    Energy Technology Data Exchange (ETDEWEB)

    Pickelmann, J.; Plank, J., E-mail: sekretariat@bauchemie.ch.tum.de

    2012-11-15

    In shotcrete, a combination of polyethylene oxide (PEO) and {beta}-naphthalene sulfonate (BNS) is commonly applied to reduce rebound. Here, the mechanism for the synergistic viscosity increase resulting from this admixture combination was investigated via x-ray diffraction (XRD), infrared and nuclear magnetic resonance (NMR) spectroscopy. It was found that the electron-rich aromatic rings present in BNS donate electrons to the alkyl protons of PEO and thus increase the electron density there. This rare interaction is known as CH-{pi} interaction and leads to the formation of a supramolecular structure whereby PEO chains bind weakly to BNS molecules. Through this mechanism a polymer network exhibiting exceptionally high molecular weight and thus viscosity is formed. Among polycondensates, sulfanilic acid-phenol-formaldehyde (SPF) provides even higher synergy with PEO than BNS while melamine (PMS), acetone (AFS) or polycarboxylate (PCE) based superplasticizers do not work at all. Effectiveness of lignosulfonates is dependent on their degree of sulfonation.

  2. Synthesis and Properties of High Strength Thin Film Composites of Poly(ethylene Oxide and PEO-PMMA Blend with Cetylpyridinium Chloride Modified Clay

    Directory of Open Access Journals (Sweden)

    Mohammad Saleem Khan

    2015-01-01

    Full Text Available Ion-conducting thin film composites of polymer electrolytes were prepared by mixing high MW poly(ethylene oxide (PEO, poly(methyl methacrylate (PMMA as a polymer matrix, cetylpyridinium chloride (CPC modified MMT as filler, and different content of LiClO4 by using solution cast method. The crystallinity, ionic conductivity (σ, and mechanical properties of the composite electrolytes and blend composites were evaluated by using XRD, AC impedance, and UTM studies, respectively. The modification of clay by CPC showed enhancement in the d-spacing. The loading of clay has effect on crystallinity of PEO systems. Blend composites showed better mechanical properties. Young’s modulus and elongation at break values showed increase with salt and clay incorporation in pure PEO. The optimum composition composite of PEO with 3.5 wt% of salt and 3.3 wt% of CPMMT exhibited better performance.

  3. Application of CPAM/PEO/PFR Retention and Drainage System in Offset Paper%CPAM/PEO/PFR三元助留助滤体系在双胶纸中的应用

    Institute of Scientific and Technical Information of China (English)

    刘全校; 朱万亮; 田居龙; 张凤山; 张长彪; 詹怀宇

    2002-01-01

    初步研究了CPAM/PEO/PFR 三元助留助滤体系在双胶纸中的应用.结果表明,该三元助留助滤体系对双胶纸浆料具有良好的助留助滤作用,适宜的CPAM/PFR的比例为25/75

  4. Genotoxicity testing of PLGA-PEO nanoparticles in TK6 cells by the comet assay and the cytokinesis-block micronucleus assay.

    Science.gov (United States)

    Kazimirova, Alena; Magdolenova, Zuzana; Barancokova, Magdalena; Staruchova, Marta; Volkovova, Katarina; Dusinska, Maria

    2012-10-09

    The in vitro genotoxicity of PLGA-PEO (poly-lactic-co-glycolic acid-polyethylene oxide copolymer) nanoparticles was assessed in TK6 cells using the comet assay as well as cytokinesis-block micronucleus (CBMN) assay. The cells were exposed to 0.12-75μg/cm² of PLGA-PEO nanoparticles during 2 and 24h for analysis in the comet assay, and to 3-75μg/cm² of these nanoparticles during 4, 24, 48 and 72h, respectively, for analysis in the CBMN assay. Two different protocols for treatment with cytochalasin B were used. We found that PLGA-PEO was neither cytotoxic (measured by relative cell growth activity and cytokinesis-block proliferation index (CBPI)), nor did it induce DNA strand-breaks (detected by the comet assay) or oxidative DNA lesions (measured by the comet assay modified with lesion-specific enzyme formamidopyrimidine-DNA-glycosylase). There were no statistically significant differences in the frequencies of micronucleated binucleated cells (MNBNCs) between untreated and treated cells in either of the conditions used. This suggests that PLGA-PEO did not have potential genotoxicity. However, using two experimental protocols of the micronucleus assay, PLGA-PEO nanoparticles showed a weak but significant increase in the level of MN in mononucleated cells, in cells treated for 48h with PLGA-PEO nanoparticles when cytochalasin B was added for the last 24h (1st protocol), and in cells treated for 24h with PLGA-PEO nanoparticles followed by washing of NPs and addition of cytochalasin B for another 24h (2nd protocol). It remains unclear whether the increase of MNMNC after treatment with PLGA-PEO nanoparticles is the effect of a possible, weak aneugenic potential or early effect of these particles, or due to another reason. These results suggest that aneugenicity in addition to clastogenicity may be considered as an important biomarker when assessing the genotoxic potential of polymeric nanoparticles.

  5. Effect of Aging Treatment on Microstructural and Mechanical Characteristics of PEO Coatings on Mg-Al Alloy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Cast Mg-6 wt pct Al alloy solution-treated at 683 K for 16 h and aged at 498 K was coated by plasma electrolytic oxidation (PEO) method. The Mg-6 wt pct Al alloy aged for 16 h exhibited the highest microhardness and wear resistance. After PEO coating, however, the microhardness and wear resistance of coatings on Mg-6 wt pct Al alloy showed a tendency to decrease with increasing aging time, which was in aggrement with the change of thickness with aging time. In addition, the coatings on solution-treated Mg-6 wt pct Al alloy had better microhardness and wear resistance than those on aged Mg-6 wt pct Al alloys. Consequently, it can be understood that the aging treatment has a deleterious influence on the mechanical properties of coatings on Mg-6 wt pct Al alloy.

  6. The changes of spectroscopic, thermal and electrical properties of PVDF/PEO containing lithium nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Elashmawi, I.S. [Department of Spectroscopy, Physics Division, National Research Center, Giza (Egypt); Department of Physics, Faculty of Science, Al-Ula, Taibah University (Saudi Arabia); Elsayed, Nadia H., E-mail: nhussein@ut.edu.sa [Department of Chemistry, Faculty of Science, University of Tabuk, Tabuk 71421 (Saudi Arabia); Department of Polymers and Pigments, National Research Center (NRC), Dokki, Cairo 12311 (Egypt); Altalhi, Fatma A. [Department of Physics, Faculty of Science, Tabuk University (Saudi Arabia)

    2014-12-25

    Highlights: • Nanocomposites of PEO/PVDF with LiTi{sub 2}O{sub 4} nanoparticles were prepared. • XRD, FTIR, SEM and thermal indicated that the addition of LiTi{sub 2}O{sub 4} can reduce the degree of crystallinity. • The conductivity–temperature plots were found to follow an Arrhenius nature. • The increase of conductivity at high frequency due to mobility of charge carriers. - Abstract: Nanocomposites films of PEO/PVDF loaded with low concentration of LiTi{sub 2}O{sub 4} nanoparticles were prepared and investigated. The X-ray diffraction (XRD) revealing the main peaks of the blend were observed. The peaks of LiTi{sub 2}O{sub 4} which were disappeared in all films indicates that the complete dissolution of LiTi{sub 2}O{sub 4} in amorphous regions. The results of XRD, FTIR, SEM and thermal studies indicated that the addition of LiTi{sub 2}O{sub 4} can reduce the degree of crystallinity of attributed to suppression of recognition of polymeric chains by LiTi{sub 2}O{sub 4} nanopowders. SEM images showed that the addition of LiTi{sub 2}O{sub 4} may improve the surface morphology. The conductivity temperature plots over frequency range 42 Hz–5 MHz under temperature range 303–433 k were found to follow an Arrhenius nature. The rise of conductivity is significant with increased LiTi{sub 2}O{sub 4} contents reveals an increase in amorphosity. The increase of conductivity at low frequency attributed to bulk conductivity and at high frequency due to mobility of charge carriers. The maximum conductivity was found at 1.548 × 10{sup −7} S cm{sup −1} for 0.5 wt.% of LiTi{sub 2}O{sub 4}. The transport number results which indicate that the charge transport in this system is predominantly due to ions. According to the above results, the samples may be exhibit superior potential for rechargeable lithium batteries.

  7. FORMATION OF FLOWER-LIKE AGGREGATES FROM SELF-ASSEMBLING OF MICELLES WITH PEO SHELLS AND CROSS-LINKED POLYACRYLAMIDE CORES

    Institute of Scientific and Technical Information of China (English)

    Chuan-qun Huang; Chun-yan Hong; Cai-yuan Pan

    2008-01-01

    Amphiphilic block copolymers, poly(ethylene oxide)-b-poly(N-acryloxysuccinimide) (PEO-b-PNAS) with various molecular weights have been successfully synthesized by atom transfer radical polymerization (ATRP) of NAS using functionalized PEO (PEO-Br) as ATRP macroinitiator. The self-assembling of the block copolymers in water, which is a good solvent for PEO and a non-solvent for PNAS, yielded spherical core-shell micelles with PNAS as core and PEO as shell. The cross-linked reaction of oxysuccinimide in PNAS chains with ethylenediamine occurred in the core of micelles,and the core cross-linked micelles were formed. The flower-like and dendritic aggregates were formed by self-assembling of the core cross-linked micelles on the glass slides or silicon wafers. Longer PNAS block in the block copolymers and higher evaporation temperature formed bigger spherical particles. The optical microscope was used to follow the formation and growth of the flower-like aggregates from the colloidal solution and the main driving forces for the self-assembling are solution fluid and interactions between PEO chains.

  8. The External Degree.

    Science.gov (United States)

    Houle, Cyril O.

    This book examines the external degree in relation to the extremes of attitudes, myths, and data. Emphasis is placed on the emergence of the American external degree, foreign external-degree programs, the purpose of the external degree, the current scene, institutional issues, and problems of general policy. (MJM)

  9. Investigation of Photocatalytic Properties of NiO/TiO2 Layers Grown via PEO/EPD Method

    OpenAIRE

    S. Bassaki; F. Golestani Fard; R. Naghizadeh; Rashidzadeh, M.

    2015-01-01

    Titanium dioxide-nickel oxide porous coatings were synthesized by Plasma Electrolytic Oxidation (PEO)/ ElectroPhoretic Deposition (EPD) in one step and within a short time. The main purpose of this research was to increase photocatalytic activity of titanium oxide by increasing surface area and coupling of titanium oxide with nickel oxide. Applied voltage effects on phase structure, surface morphology and photocatalytic efficiency of coatings were studied. Phase structure and surface morpholo...

  10. Molecular dynamics and a spectroscopic study of sulfur dioxide absorption by an ionic liquid and its mixtures with PEO.

    Science.gov (United States)

    Hoher, Karina; Cardoso, Piercarlo F; Lepre, Luiz F; Ando, Rômulo A; Siqueira, Leonardo J A

    2016-10-19

    An investigation comprising experimental techniques (absorption capacity of SO2 and vibrational spectroscopy) and molecular simulations (thermodynamics, structure, and dynamics) has been performed for the polymer poly(ethylene oxide) (PEO), the ionic liquid butyltrimethylammonium bis(trifluoromethylsulfonyl)imide ([N4111][Tf2N]) and their mixtures as sulfur dioxide (SO2) absorbing materials. The polymer PEO has higher capacity to absorb SO2 than the neat ionic liquid, whereas the mixtures presented intermediary absorption capacities. The band assigned to the symmetric stretching band of SO2 at ca. 1140 cm(-1), which is considered a spectroscopic probe for the strength of SO2 interactions with its neighborhood, shifts to lower wavenumbers as more negative total interaction energy values of SO2 were evaluated from the simulations. The solvation free energy of SO2, ΔGsol, correlates linearly with the absorption capacity of SO2. The negative values of ΔGsol are due to negative and positive values of enthalpy and entropy, respectively. In the ionic liquid, SO2 weakens the cation-anion interactions, whereas in the mixture with a high content of PEO these interactions are slightly increased. Such effects were correlated with the relative population of cisoid and transoid conformers of Tf2N anions as revealed by Raman spectroscopy. Moreover, the presence of SO2 in the systems provokes the increase of diffusion coefficients of the absorbing species in comparison with the systems without the gas. Proper to the slow dynamics of the polymer, the diffusion coefficient of ions and SO2 diminishes with the increase of the PEO content.

  11. Synthesis and Characterization of (PEO)x - (V0.85 Mo0.15)2O5 Nanocomposite Films

    Institute of Scientific and Technical Information of China (English)

    JIANG Cong-sheng; GUO Li-ling

    2003-01-01

    ( PEO )x- ( V0.85 Mo0.15 )2O5 ( x = 0, 0. 5,1.0) nanocomposite films were prepared by a modified sol-gel method. The structure of the films was analyzed by XRD , and the DC electrical conductivity. Cyclic voltammogram and optical spectral transmittance were investigated. The results show that the ( V0.85 Mo0.15 )2O5 xerogel has a layered structure and its interlayer space increased from 1.3181 mn at x = 0 to 1. 7897 nm at x =1.0. The introduction of MoO3 improved the DC electrical conductivities of the films due to the generntion of V4 +to maintain the electrical neutrality of the oxides. PEO intercalated in the interlayer of ( V0.85 Mo0.15 )2 O5 oxides has interaction with the oxidles, enhancing the amount of Li + iotas inserted into the interlayer of the oxides. Moreover , the intercalation of PEO into the interlayer of ( V0.85 Mo0.15 )2 O5 oxides improved the cathodic electrochromic property in near ultraviolet region and anodic electrochromic property in visible rauge.

  12. Investigation of absorptance and emissivity of thermal control coatings on Mg–Li alloys and OES analysis during PEO process

    Science.gov (United States)

    Yao, Zhongping; Xia, Qixing; Ju, Pengfei; Wang, Jiankang; Su, Peibo; Li, Dongqi; Jiang, Zhaohua

    2016-07-01

    Thermal control ceramic coatings on Mg–Li alloys have been successfully prepared in silicate electrolyte system by plasma electrolytic oxidation (PEO) method. The PEO coatings are mainly composed of crystallized Mg2SiO4 and MgO, which have typical porous structure with some bulges on the surface; OES analysis shows that the plasma temperature, which is influenced by the technique parameters, determines the formation of the coatings with different crystalline phases and morphologies, combined with “quick cooling effect” by the electrolyte; and the electron concentration is constant, which is related to the electric spark breakdown, determined by the nature of the coating and the interface of coating/electrolyte. Technique parameters influence the coating thickness, roughness and surface morphology, but do not change the coating composition in the specific PEO regime, and therefore the absorptance (αS) and emissivity (ε) of the coatings can be adjusted by the technique parameters through changing thickness and roughness in a certain degree. The coating prepared at 10 A/dm2, 50 Hz, 30 min and 14 g/L Na2SiO3 has the minimum value of αS (0.35) and the maximum value of ε (0.82), with the balance temperature of 320 K.

  13. The Influence of Various Additives on the Properties of Peo Coatings Formed on AZ31 mg Alloy

    Science.gov (United States)

    Rehman, Zeeshan Ur; Ahn, Byung-Hyun; Jeong, Yeong Seung; Song, Jung-Il; Koo, Bon-Heun

    2016-03-01

    In this work, plasma electrolytic oxidation (PEO) ceramic coatings were prepared on magnesium AZ31B alloy. Various electrolyte solutions including phosphate, aluminate and silicate as additives and NaOH + Na2SiF6 as constant agent were used to prepare the coatings. Influence of the additives on chemical composition and structure of the PEO coatings were examined by means of scanning electron microscope (SEM) and XRD. From structural analysis it was found that coatings prepared in the aluminate-based electrolyte have the best structural features. Microhardness and tribological characteristics of the PEO coatings were investigated using Vickers hardness test and pin-on-disc test. Microhardness for aluminate-based coating was found to be 1169.63HV while those for silicate-and phosphate-based coatings were 1093.42HV and 285.91HV, respectively. Wear rate of the aluminate-based coating was found to be lowest than all other coatings having a value of 2.78×10-3mg/Nm.

  14. Investigation of absorptance and emissivity of thermal control coatings on Mg-Li alloys and OES analysis during PEO process.

    Science.gov (United States)

    Yao, Zhongping; Xia, Qixing; Ju, Pengfei; Wang, Jiankang; Su, Peibo; Li, Dongqi; Jiang, Zhaohua

    2016-07-07

    Thermal control ceramic coatings on Mg-Li alloys have been successfully prepared in silicate electrolyte system by plasma electrolytic oxidation (PEO) method. The PEO coatings are mainly composed of crystallized Mg2SiO4 and MgO, which have typical porous structure with some bulges on the surface; OES analysis shows that the plasma temperature, which is influenced by the technique parameters, determines the formation of the coatings with different crystalline phases and morphologies, combined with "quick cooling effect" by the electrolyte; and the electron concentration is constant, which is related to the electric spark breakdown, determined by the nature of the coating and the interface of coating/electrolyte. Technique parameters influence the coating thickness, roughness and surface morphology, but do not change the coating composition in the specific PEO regime, and therefore the absorptance (αS) and emissivity (ε) of the coatings can be adjusted by the technique parameters through changing thickness and roughness in a certain degree. The coating prepared at 10 A/dm(2), 50 Hz, 30 min and 14 g/L Na2SiO3 has the minimum value of αS (0.35) and the maximum value of ε (0.82), with the balance temperature of 320 K.

  15. Surface properties of AZ91 magnesium alloy after PEO treatment using molybdate salts and low current densities

    Science.gov (United States)

    Pezzato, Luca; Brunelli, Katya; Napolitani, Enrico; Magrini, Maurizio; Dabalà, Manuele

    2015-12-01

    Plasma electrolytic oxidation (PEO) process is a recently developed electrochemical method used to produce on the surface of various metals oxide ceramic coatings that improve corrosion and wear properties of the substrate. In this work, PEO process was applied on AZ91 magnesium alloy using low current densities (0.05 A/cm2) and an alkaline solution of silicates with different concentrations of sodium molybdate (0.3-3 g/l). The effect of the low current densities of process and of molybdate salts on the corrosion resistance of the coatings was studied with potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS) in chloride and sulfate environment. The morphology, the phases and the chemical composition of the coatings were examined using a scanning electron microscope equipped with EDS, X-ray diffraction, secondary ion mass spectrometry and X-ray photoelectron spectroscopy. The corrosion properties of the PEO coated samples were remarkably improved if compared with the uncoated samples. The addition of sodium molybdate, in determinate conditions, had a positive effect on the characteristics of the coatings in terms of corrosion resistance.

  16. Investigation of absorptance and emissivity of thermal control coatings on Mg–Li alloys and OES analysis during PEO process

    Science.gov (United States)

    Yao, Zhongping; Xia, Qixing; Ju, Pengfei; Wang, Jiankang; Su, Peibo; Li, Dongqi; Jiang, Zhaohua

    2016-01-01

    Thermal control ceramic coatings on Mg–Li alloys have been successfully prepared in silicate electrolyte system by plasma electrolytic oxidation (PEO) method. The PEO coatings are mainly composed of crystallized Mg2SiO4 and MgO, which have typical porous structure with some bulges on the surface; OES analysis shows that the plasma temperature, which is influenced by the technique parameters, determines the formation of the coatings with different crystalline phases and morphologies, combined with “quick cooling effect” by the electrolyte; and the electron concentration is constant, which is related to the electric spark breakdown, determined by the nature of the coating and the interface of coating/electrolyte. Technique parameters influence the coating thickness, roughness and surface morphology, but do not change the coating composition in the specific PEO regime, and therefore the absorptance (αS) and emissivity (ε) of the coatings can be adjusted by the technique parameters through changing thickness and roughness in a certain degree. The coating prepared at 10 A/dm2, 50 Hz, 30 min and 14 g/L Na2SiO3 has the minimum value of αS (0.35) and the maximum value of ε (0.82), with the balance temperature of 320 K. PMID:27383569

  17. Multi-physics study of plasma in liquids: The case of Plasma Electrolytic Oxidation (PEO)

    Science.gov (United States)

    Nomine, Alexandre; Troughton, Sam; Nomine, Anna; Henrion, Gerard; Clyne, Bill

    2015-09-01

    PEO is a promising technique in order to grow rapidly oxide coatings with high corrosion and wear resistance. Oxidation is driven by millions of simultaneous micro-discharges (MD) that occur at the interface between the substrate and the liquid electrolyte. However, the mechanisms of breakdown and the subsequent oxidation are not well understood yet. Current profiles and Ultra-Fast Imaging of single discharges allows to correlate the size and life-time of the discharge with different electric parameters (Q, Imax). MD are found to appear in cascade, switching on and off with a frequency in the order of 1-10 kHz. Formation of a bubble is observed directly after the ignition of the discharge. The growth rate that varies between 1 and 10 m/s, is used to estimate the gas pressure in the bubble. The influence of the pulse frequency on the bubble shape and on the coatings will be presented. MD size and life time are known to increase with coating thickness presumably due to higher charge accumulation. This study shows that ms scale, the evolution of MD size and life time evaluates similarly, suggesting that the coating thickness is not the only parameter governing the MD size and life-time. second affiliation: The Open University.

  18. Change spectroscopic studies and optimization electrical properties of PVP/PEO doped copper phthalocyanines

    Energy Technology Data Exchange (ETDEWEB)

    Ragab, H.M., E-mail: yara20092009@yahoo.com [Department of Physics, Faculty of Science, Al-Azhar University, Girls Branch, Cairo 11754 (Egypt); Basic Science Department, Faculty of Preparatory Year, Hail University (Saudi Arabia); Ahmad, F.; Radwan, Sh.N. [Department of Physics, Faculty of Science, Al-Azhar University, Girls Branch, Cairo 11754 (Egypt)

    2016-12-01

    Composite films of polyvinyl pyrrolidone and Polyethylene oxide (PVP/PEO) blend doped with 1, 4 and 12 wt% of copper Phthalocyanines (CuPc) were prepared by casting method. The samples were studied using different techniques. The X-ray (XRD) revealed average crystallite size and X-ray intensity decrease at 1 CuPc %; this implies to an increase on the degree of amorphousity, then increase at CuPc >1%. The change in both the intensity and position of some absorption peaks of the blend with CuPc content were observed in Fourier transform infrared (FTIR) spectroscopy suggest the complexation of polymer blend. The UV–Vis spectroscopy revealed that the optical band gap decreases as well as band tail width increases with increasing CuPc concentration. It may be reflect the role of CuPc in modifying the electronic structure of the polymeric matrix. The charge carrier concentration is responsible for conductivity improvement in electrolytes rather than the mobility.

  19. Change spectroscopic studies and optimization electrical properties of PVP/PEO doped copper phthalocyanines

    Science.gov (United States)

    Ragab, H. M.; Ahmad, F.; Radwan, Sh. N.

    2016-12-01

    Composite films of polyvinyl pyrrolidone and Polyethylene oxide (PVP/PEO) blend doped with 1, 4 and 12 wt% of copper Phthalocyanines (CuPc) were prepared by casting method. The samples were studied using different techniques. The X-ray (XRD) revealed average crystallite size and X-ray intensity decrease at 1 CuPc %; this implies to an increase on the degree of amorphousity, then increase at CuPc >1%. The change in both the intensity and position of some absorption peaks of the blend with CuPc content were observed in Fourier transform infrared (FTIR) spectroscopy suggest the complexation of polymer blend. The UV-Vis spectroscopy revealed that the optical band gap decreases as well as band tail width increases with increasing CuPc concentration. It may be reflect the role of CuPc in modifying the electronic structure of the polymeric matrix. The charge carrier concentration is responsible for conductivity improvement in electrolytes rather than the mobility.

  20. Loop-Closure and Gaussian Models of Collective Structural Characteristics of Capped PEO Oligomers in Water

    CERN Document Server

    Chaudhari, M I; Paulaitis, M E

    2014-01-01

    Parallel-tempering MD results for a CH$_3$(CH$_2$-O-CH$_2$)$_m$CH$_3$ chain in water are exploited as a data-base for analysis of collective structural characteristics of the PEO globule with a goal of defining models permitting statistical thermodynamic analysis of dispersants of Corexit type. The chain structure factor, relevant to neutron scattering from a deuterated chain in neutral water, is considered specifically. The traditional continuum-Gaussian structure factor is inconsistent with the simple $k \\rightarrow \\infty$ behavior, but we consider a discrete-Gaussian model that does achieve that consistency. Shifting-and-scaling the discrete-Gaussian model helps to identify the low-$k$ to high-$k$ transition near $k \\approx 2\\pi/0.6 \\mathrm{nm}$ when an empirically matched number of Gaussian links is about one-third of the total number of effective-atom sites. This short distance-scale boundary of 0.6 nm is directly verified with the $r$-space distributions, and this distance is thus identified with a nat...

  1. Regulating multiple externalities

    DEFF Research Database (Denmark)

    Waldo, Staffan; Jensen, Frank; Nielsen, Max

    2016-01-01

    Open access is a well-known externality problem in fisheries causing excess capacity and overfishing. Due to global warming, externality problems from CO2 emissions have gained increased interest. With two externality problems, a first-best optimum can be achieved by using two regulatory instrume......Open access is a well-known externality problem in fisheries causing excess capacity and overfishing. Due to global warming, externality problems from CO2 emissions have gained increased interest. With two externality problems, a first-best optimum can be achieved by using two regulatory...

  2. ExternE National Implementation Finland

    Energy Technology Data Exchange (ETDEWEB)

    Pingoud, K.; Maelkki, H.; Wihersaari, M.; Pirilae, P. [VTT Energy, Espoo (Finland); Hongisto, M. [Imatran Voima Oy, Vantaa (Finland); Siitonen, S. [Ekono Energy Ltd, Espoo (Finland); Johansson, M. [Finnish Environment Institute, Helsinki (Finland)

    1999-07-01

    ExternE National Implementation is a continuation of the ExternE Project, funded in part by the European Commission's Joule III Programme. This study is the result of the ExternE National Implementation Project for Finland. Three fuel cycles were selected for the Finnish study: coal, peat and wood-derived biomass, which together are responsible for about 40% of total electricity generation in Finland and about 75% of the non-nuclear fuel based generation. The estimated external costs or damages were dominated by the global warming (GW) impacts in the coal and peat fuel cycles, but knowledge of the true GW impacts is still uncertain. From among other impacts that were valued in monetary terms the human health damages due to airborne emissions dominated in all the three fuel cycles. Monetary valuation for ecosystem impacts is not possible using the ExternE methodology at present. The Meri-Pori power station representing the coal fuel cycle is one of the world's cleanest and most efficient coal-fired power plants with a condensing turbine. The coal is imported mainly from Poland. The estimated health damages were about 4 mECU/kWh, crop damages an order of magnitude lower and damages caused to building materials two orders of magnitude lower. The power stations of the peat and biomass fuel cycles are of CHP type, generating electricity and heat for the district heating systems of two cities. Their fuels are of domestic origin. The estimated health damages allocated to electricity generation were about 5 and 6 mECU/kWh, respectively. The estimates were case-specific and thus an generalisation of the results to the whole electricity generation in Finland is unrealistic. Despite the uncertainties and limitations of the methodology, it is a promising tool in the comparison of similar kinds of fuel cycles, new power plants and pollution abatement technologies and different plant locations with each other. (orig.)

  3. Performance characteristics of guanine incorporated PVDF-HFP/PEO polymer blend electrolytes with binary iodide salts for dye-sensitized solar cells

    Science.gov (United States)

    Senthil, R. A.; Theerthagiri, J.; Madhavan, J.; Arof, A. K.

    2016-08-01

    In this work, we have investigated the influence of guanine as an organic dopant in dye-sensitized solar cell (DSSC) based on poly(vinylidinefluoride-co-hexafluoropropylene) (PVDF-HFP)/polyethylene oxide (PEO) polymer blend electrolyte along with binary iodide salts (potassium iodide (KI) and tetrabutylammonium iodide (TBAI)) and iodine (I2). The PVDF-HFP/KI + TBAI/I2, PVDF-HFP/PEO/KI + TBAI/I2 and guanine incorporated PVDF-HFP/PEO/KI + TBAI/I2 electrolytes were prepared by solution casting technique using DMF as solvent. The PVDF-HFP/KI + TBAI/I2 electrolyte showed an ionic conductivity value of 9.99 × 10-5 Scm-1, whereas, it was found to be increased to 4.53 × 10-5 Scm-1 when PEO was blended with PVDF-HFP/KI + TBAI/I2 electrolyte. However, a maximum ionic conductivity value of 3.67 × 10-4 Scm-1 was obtained for guanine incorporated PVDF-HFP/PEO/KI + TBAI/I2 blend electrolyte. The photovoltaic properties of all these polymer electrolytes in DSSCs were characterized. As a consequence, the power conversion efficiency of the guanine incorporated PVDF-HFP/PEO/KI + TBAI/I2 electrolyte based DSSC was significantly improved to 4.98% compared with PVDF-HFP/PEO/KI + TBAI/I2 electrolyte based DSSC (2.46%). These results revealed that the guanine can be an effective organic dopant to enhance the performance of DSSCs.

  4. Hybrid Randomly Electrospun Poly(lactic-co-glycolic acid):Poly(ethylene oxide) (PLGA:PEO) Fibrous Scaffolds Enhancing Myoblast Differentiation and Alignment.

    Science.gov (United States)

    Evrova, Olivera; Hosseini, Vahid; Milleret, Vincent; Palazzolo, Gemma; Zenobi-Wong, Marcy; Sulser, Tullio; Buschmann, Johanna; Eberli, Daniel

    2016-11-23

    Cellular responses are regulated by their microenvironments, and engineered synthetic scaffolds can offer control over different microenvironment properties. This important relationship can be used as a tool to manipulate cell fate and cell responses for different biomedical applications. We show for the first time in this study how blending of poly(ethylene oxide) (PEO) to poly(lactic-co-glycolic acid) (PLGA) fibers to yield hybrid scaffolds changes the physical and mechanical properties of PLGA fibrous scaffolds and in turn affects cellular response. For this purpose we employed electrospinning to create fibrous scaffolds mimicking the basic structural properties of the native extracellular matrix. We introduced PEO to PLGA electrospun fibers by spinning a blend of PLGA:PEO polymer solutions in different ratios. PEO served as a sacrificial component within the fibers upon hydration, leading to pore formation in the fibers, fiber twisting, increased scaffold disintegration, and hydrophilicity, decreased Young's modulus, and significantly improved strain at break of initially electrospun scaffolds. We observed that the blended PLGA:PEO fibrous scaffolds supported myoblast adhesion and proliferation and resulted in increased myotube formation and self-alignment, when compared to PLGA-only scaffolds, even though the scaffolds were randomly oriented. The 50:50 PLGA:PEO blended scaffold showed the most promising results in terms of mechanical properties, myotube formation, and alignment, suggesting an optimal microenvironment for myoblast differentiation from the PLGA:PEO blends tested. The explored approach for tuning fiber properties can easily extend to other polymeric scaffolds and provides a valuable tool to engineer fibrillar microenvironments for several biomedical applications.

  5. ASH External Web Portal (External Portal) -

    Data.gov (United States)

    Department of Transportation — The ASH External Web Portal is a web-based portal that provides single sign-on functionality, making the web portal a single location from which to be authenticated...

  6. Improvement of ionic conductivity and performance of quasi-solid-state dye sensitized solar cell using PEO/PMMA gel electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Aram, E. [Iran Polymer and Petrochemical Institute, 14965/115 Tehran (Iran, Islamic Republic of); Ehsani, M., E-mail: m.ehsani@ippi.ac.ir [Iran Polymer and Petrochemical Institute, 14965/115 Tehran (Iran, Islamic Republic of); Khonakdar, H.A. [Iran Polymer and Petrochemical Institute, 14965/115 Tehran (Iran, Islamic Republic of); Leibniz Institute of Polymer Research, D-01067 Dresden (Germany)

    2015-09-10

    Graphical abstract: Reduced interfacial resistance of a quasi-solid-state dye sensitized solar cell with PEO/PMMA blend gel electrolytes. - Highlights: • A new polymer gel electrolyte containing PEO/PMMA was developed for DSSCs. • Optimization of polymer gel electrolyte was done for dye sensitized solar cell. • The best ionic conductivity was found in PEO/PMMA blend with 10/90 w/w composition. • The DSSC with the PEO/PMMA based electrolyte showed good photovoltaic performance. • Significant stability improvement for quasi-solid state DSSC was obtained. - Abstract: Polymer blend gel electrolytes based on polyethylene oxide (PEO) and poly(methyl methacrylate) (PMMA) as host polymers with various weight ratios, LiI/I{sub 2} as redox couple in electrolyte and 4-tert-butyl pyridine as additive were prepared by solution method. The introduction of PMMA in the PEO gel electrolyte reduced the degree of crystallinity of PEO, which was confirmed by differential scanning calorimetry (DSC). Complexation and ionic conductivity as a function of temperature were investigated with Fourier transform infrared and ionic conductometry, respectively. A good correlation was found between the degree of crystallinity and ionic conductivity. The reduction in crystallinity, governed by blending ratio, led to improvement of ionic conductivity. The best ionic conductivity was attained in PEO/PMMA blend with 10/90 w/w composition. The performance of a quasi-solid-state dye sensitized solar cell using the optimized polymer gel electrolyte was investigated. The optimized system of high ionic conductivity of 7 mS cm{sup −1}, with fill factor of 0.59, short-circuit density of 11.11 mA cm{sup −2}, open-circuit voltage of 0.75 V and the conversion efficiency of 4.9% under air mass 1.5 irradiation (100 mW cm{sup −2}) was obtained. The long-term stability of the dye-sensitized solar cell (DSSC) during 600 h was improved by using PEO/PMMA gel electrolyte relative to a liquid type

  7. Salt effects on the air/solution interfacial properties of PEO-containing copolymers: equilibrium, adsorption kinetics and surface rheological behavior.

    Science.gov (United States)

    Llamas, Sara; Mendoza, Alma J; Guzmán, Eduardo; Ortega, Francisco; Rubio, Ramón G

    2013-06-15

    Lithium cations are known to form complexes with the oxygen atoms of poly(oxyethylene) chains. The effect of Li(+) on the surface properties of three block-copolymers containing poly(oxyethylene) (PEO) have been studied. Two types of copolymers have been studied, a water soluble one of the pluronic family, PEO-b-PPO-b-PEO, PPO being poly(propyleneoxyde), and two water insoluble ones: PEO-b-PS and PEO-b-PS-b-PEO, PS being polystyrene. In the case of the pluronic the adsorption kinetics, the equilibrium surface tension isotherm and the aqueous/air surface rheology have been measured, while for the two insoluble copolymers only the surface pressure and the surface rheology have been studied. In all the cases two different Li(+) concentrations have been used. As in the absence of lithium ions, the adsorption kinetics of pluronic solutions shows two processes, and becomes faster as [Li(+)] increases. The kinetics is not diffusion controlled. For a given pluronic concentration the equilibrium surface pressure increases with [Li(+)], and the isotherms show two surface phase transitions, though less marked than for [Li(+)]=0. A similar behavior was found for the equilibrium isotherms of PEO-b-PS and PEO-b-PS-b-PEO. The surface elasticity of these two copolymers was found to increase with [Li(+)] over the whole surface concentration and frequency ranges studied. A smaller effect was found in the case of the pluronic solutions. The results of the pluronic solutions were modeled using a recent theory that takes into account that the molecules can be adsorbed at the surface in two different states. The theory gives a good fit for the adsorption kinetics and a reasonably good prediction of the equilibrium isotherms for low and intermediate concentrations of pluronic. However, the theory is not able to reproduce the isotherm for [Li(+)]=0. Only a semi-quantitative prediction of the surface elasticity is obtained for [pluronic]≤1×10(-3) mM.

  8. Energy transfer based photoluminescence properties of co-doped (Er3+ + Pr3+): PEO + PVP blended polymer composites for photonic applications

    Science.gov (United States)

    Naveen Kumar, K.; Kang, Misook; Bhaskar Kumar, G.; Ratnakaram, Y. C.

    2016-04-01

    Er3+, Pr3+ singly doped and co-doped PEO + PVP polymer composites have been synthesized by conventional solution casting method. The structural analysis has been carried out for all these polymer composites from XRD analysis. Raman spectral studies confirm the ion-polymer interactions and polymer complex formation. Thermal properties of pure polymer film has also been clearly elucidated by TG/DTA profiles. Well defined optical absorption bands pertaining to Er3+ and Pr3+ are observed in the absorption spectral profile and these bands are assigned with corresponding electronic transitions. The polymer films containing singly doped Er3+ and Pr3+ ions have displayed green and red emissions at 510 nm (2H11/2 → 4I15/2) and 688 nm (3P0 → 3F3) respectively under UV excitation source. Comparing the emission spectra of singly Er3+ and co-doped Er3+ + Pr3+: PEO + PVP polymer films, a significant red emission pertaining to Pr3+ions is remarkably enhanced in co-doped polymer system. This could be ascribed to possible energy transfer from Er3+ to Pr3+ in co-doped polymer system. The energy transfer mechanism is clearly demonstrated using their emission performances, overlapped spectral profiles and also life time decay dynamics. Thus, it could be suggested that Er3+: PEO + PVP, Pr3+: PEO + PVP and (Er3+ + Pr3+): PEO + PVP blended polymer films are potential materials for several photonic applications.

  9. Behaviors of keratinocytes and fibroblasts on films of PLA50-PEO-PLA50 triblock copolymers with various PLA segment lengths.

    Science.gov (United States)

    Garric, Xavier; Garreau, Henri; Vert, Michel; Molès, Jean-Pierre

    2008-04-01

    The growth of human primary keratinocytes and fibroblasts on PLA-PEO-PLA copolymer films was investigated as an intermediate stage of a strategy aimed at making implantable dermo-epidermal substitutes. Four PLA-PEO-PLA triblock copolymers with the same PEO block and different DL-lactic acid/ethylene oxide molar ratios (LA/EO) (0.8, 1.4, 1.8 and 2), were synthesized and characterized by 1H-nuclear magnetic resonance and infrared spectroscopy. The films made of these copolymers were more hydrophilic than PLA50 and than tissue culture polystyrene controls according to contact angles with water. Proliferation and adhesion of human skin cells were evaluated by MTT assay and by scanning electron microscopy. The presence of PEO in the triblock copolymers influenced cell adhesion and proliferation of fibroblasts, whereas keratinocyte adhesion and proliferation were not affected. These features emphasize the interest of PLA-PEO-PLA triblock copolymers to serve as better compounds than the racemic PLA previously investigated to make supports for human skin primary cells and scaffolds for skin engineering.

  10. Preparation and properties of PEO/LiClO4/KH560-SiO2 composite polymer electrolyte by sol-gel composite-in-situ method

    Institute of Scientific and Technical Information of China (English)

    PAN Chun-yue; GAO Jin-huan; ZHANG Qian; FENG Qing; CHAO meng

    2008-01-01

    Composite polymer electrolytes based on polyethylene oxide (PEO) were prepared by using LiClO4 as doping salt and silane-modified SiO2 as filler. SiO2 was formed in-situ in (PEO)8LiClO4 matrix by the hydrolysis and condensation reaction of Si(OC4H9)4. The crystallinity, morphology and ionic conductivity of composite polymer electrolyte films were examined by differential scanning calorimetry, scanning electron microscopy, atom force microscopy and alternating current impedance spectroscopy, respectively. Compared with the crystallinity of the unmodified SiO2 as inert filler, that of composite polymer electrolytes is decreased. The results show that silane-modified SiO2 particles are uniformly dispersed in (PEO)8LiClO4 composite polymer electrolyte film and the addition of silane-modified SiO2 increases the ionic conductivity of the (PEO)8LiClO4 more noticeably. When the mass fraction of SiO2 is about 10%, the conductivity of (PEO)8LiClO4-modified SiO2 attains a maximum value of 4.8×10-5S·cm-1.

  11. 慢性进行性眼外肌瘫痪型线粒体肌病(附3个家系报告)%Chronic progressive external ophthalmoplegia type of mitochondrial myopathy(report of 3 families)

    Institute of Scientific and Technical Information of China (English)

    王勤周; 焉传祝; 吴金玲; 刘淑萍; 张永庆; 高素琴; 刘新云; 李大年

    2005-01-01

    目的探讨家族性慢性进行性眼外肌瘫痪(CPEO)型线粒体肌病的临床、遗传和病理特点.方法回顾性分析CPEO 型线粒体肌病3个家系21例患者的临床表现、家系调查及5例肌活检病理学资料.结果患者临床均表现为眼睑下垂和眼球运动障碍,伴或不伴有肌无力.1家系符合常染色体显性遗传规律,另2个家系符合母系遗传规律.病理改变:光镜下为破碎红纤维(RRFs)和细胞色素C氧化酶(COX)缺失纤维;电镜为肌膜下、肌原纤维间线粒体数量增多,嵴内可见电子致密颗粒或晶格样包涵体.结论 3个家系及其亲子代间临床与病理表现相似,提示不同遗传方式所致CPEO型线粒体肌病临床表现是相同的.

  12. An epichlorohydrin-crosslinked semi-interpenetrating GG-PEO network as a xerogel matrix for sustained release of sulpiride.

    Science.gov (United States)

    Hoosain, Famida G; Choonara, Yahya E; Kumar, Pradeep; Tomar, Lomas K; Tyagi, Charu; du Toit, Lisa C; Pillay, Viness

    2014-10-01

    The current study involved the development of a novel sustained release crosslinked semi-IPN xerogel matrix tablet prepared by chemical crosslinking of poly(ethylene) oxide (PEO) and gellan gum (GG) employing epichlorohydrin (EPI) as crosslinker. A Box-Behnken design was employed for the statistical optimization of the matrix system to ascertain the ideal combination of native polymeric and crosslinking agents. Characterization studies were performed by employing standard polymer characterization techniques such as Fourier transform infrared spectrometry, differential scanning calorimetry, and scanning electron microscopy. Formulated matrix tablets displayed zero-order release kinetics, extending over 24 h. The mechanism of drug release was primarily by swelling and surface erosion. Crosslinked semi-IPN xerogel matrix tablets were compared to non-crosslinked polymer blends; results from the study conducted showed that the physiochemical properties of the PEO and GG were sufficiently modified to allow for sustained release of sulpiride with a 100% drug release at 24 h in a controlled manner as compared to non-crosslinked formulations which displayed further release beyond the test period. Crosslinked formulations displayed water uptake between 450 and 500% indicating a controlled rate of swelling and erosion allowing for sustained release. Surface morphology of the crosslinked system depicted a porous structure formed by interpenetrating networks of polymers, allowing for a greater degree of controlled penetration into the system affording it the ability to sustain drug release. Therefore, conclusively, based on the study performed, crosslinked PEO-GG allows for the sustained release of sulpiride from a hydrophilic semi-IPN xerogel matrix system.

  13. Hemocompatibility and selective cell fate of polydopamine-assisted heparinized PEO/PLLA composite coating on biodegradable AZ31 alloy.

    Science.gov (United States)

    Wei, Zhongling; Tian, Peng; Liu, Xuanyong; Zhou, Bangxin

    2014-09-01

    Biodegradable magnesium and its alloys have attracted much attention, as they have been used as cardiovascular stents recently because of their biodegradation after implantation. However, their corrosion resistance, hemocompatibility and surface biocompatibility are needed for practical applications. In this work, heparinization of the plasma electrolytic oxidation/poly(l-lactic acid) (PEO/PLLA) composite coating on biodegradable AZ31 alloy was achieved by the strong adhesion of mussel-inspired polydopamine (PDAM). The corrosion resistance of the coated substrates was evaluated in simulated body fluid. In particular, the hemolysis ratio and platelet adhesion tests were conducted to evaluate the hemocompatibility of the composite coatings. The in vitro cytotoxicity of the composite coatings was evaluated with human umbilical vein endothelial cells (HUVECs). The adhesion and proliferation of HUVECs and human umbilical artery smooth muscle cells (HUASMCs) directly incubated on the composite coatings were also investigated. The results showed that although PDAM modification and further heparinization reduced the corrosion resistance of the PEO/PLLA composite coating, the protection of the coating for the substrate was mainly maintained. Moreover, PDAM modification and further heparinization significantly suppressed the adhesion of platelets and had little influence on sustaining a low hemolysis ratio thus resulting in good surface hemocompatibility of the composite coating. The in vitro cell test demonstrated that none of the composite coatings presented obvious cytotoxicity. Significantly, after surface heparinization, the composite coating became more suitable for HUVEC growth and simultaneously inhibited HUASMC growth. The results show that further modification of the PEO/PLLA composite coating on biodegradable magnesium alloy is a promising method to obtain good surface hemocompatibility for anticoagulation and to regulate the cell fate for fast re

  14. Ion conduction and relaxation in PEO-LiTFSI-Al{sub 2}O{sub 3} polymer nanocomposite electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Das, S.; Ghosh, A., E-mail: sspag@iacs.res.in [Department of Solid State Physics, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India)

    2015-05-07

    Ion conduction and relaxation in PEO-LiTFSI-Al{sub 2}O{sub 3} polymer nanocomposite electrolytes have been studied for different concentrations of Al{sub 2}O{sub 3} nanoparticles. X-ray diffraction and differential scanning calorimetric studies show that the maximum amorphous phase of PEO is observed for PEO-LiTFSI embedded with 5 wt. % Al{sub 2}O{sub 3}. The maximum ionic conductivity ∼3.3 × 10{sup −4} S cm{sup −1} has been obtained for this composition. The transmission electron microscopic image shows a distribution of Al{sub 2}O{sub 3} nanoparticles in all compositions with size of <50 nm. The temperature dependence of the ionic conductivity follows Vogel-Tamman-Fulcher nature, indicating a strong coupling between ionic and polymer chain segmental motions. The scaling of the ac conductivity implies that relaxation dynamics follows a common mechanism for different temperatures and Al{sub 2}O{sub 3} concentrations. The imaginary modulus spectra are asymmetric and skewed toward the high frequency sides of the maxima and analyzed using Havriliak-Negami formalism. The temperature dependence of the relaxation time obtained from modulus spectra also exhibits Vogel-Tamman-Fulcher nature. The values of the stretched exponent obtained from Kohlrausch-Williams-Watts fit to the modulus data are fairly low, suggesting highly non-exponential relaxation for all concentrations of Al{sub 2}O{sub 3} in these electrolytes.

  15. Effect of organic acids and nano-sized ceramic doping on PEO-based solid polymer electrolytes

    Science.gov (United States)

    Park, Jae Won; Jeong, Euh Duck; Won, Mi-Sook; Shim, Yoon-Bo

    Composite solid polymer electrolytes (CSPEs) consisting of polyethyleneoxide (PEO), LiClO 4, organic acids (malonic, maleic, and carboxylic acids), and/or Al 2O 3 were prepared in acetonitrile. CSPEs were characterized by Brewster Angle Microscopy (BAM), thermal analysis, ac impedance, cyclic voltammetry, and tested for charge-discharge capacity with the Li or LiNi 0.5Co 0.5O 2 electrodes coated on stainless steel (SS). The morphologies of the CSPE films were homogeneous and porous. The differential scanning calorimetric (DSC) results suggested that performance of the CSPE film was highly enhanced by the acid and inorganic additives. The composite membrane doped with organic acids and ceramic showed good conductivity and thermal stability. The ac impedance data, processed by non-linear least square (NLLS) fitting, showed good conducting properties of the composite films. The ionic conductivity of the film consisting of (PEO) 8LiClO 4:citric acid (99.95:0.05, w/w%) was 3.25 × 10 -4 S cm -1 and 1.81 × 10 -4 S cm -1 at 30 °C. The conductivity has further improved to 3.81 × 10 -4 S cm -1 at 20 °C by adding 20 w/w% Al 2O 3 filler to the (PEO) 8LiClO 4 + 0.05% carboxylic acid composite. The experimental data for the full cell showed an upper limit voltage window of 4.7 V versus Li/Li + for CSPE at room temperature.

  16. Aqueous self-assembly of poly(ethylene oxide)-block-poly(ε-caprolactone) (PEO-b-PCL) copolymers: disparate diblock copolymer compositions give rise to nano- and meso-scale bilayered vesicles.

    Science.gov (United States)

    Qi, Wei; Ghoroghchian, P Peter; Li, Guizhi; Hammer, Daniel A; Therien, Michael J

    2013-11-21

    Nanoparticles formed from diblock copolymers of FDA approved PEO and PCL have generated considerable interest as in vivo drug delivery vehicles. Herein, we report the synthesis of the most extensive family PEO-b-PCL copolymers that vary over the largest range of number-average molecular weights (Mn: 3.6-57k), PEO weight fractions (fPEO: 0.08-0.33), and PEO chain lengths (0.75-5.8k) reported to date. These polymers were synthesized in order to establish the full range of aqueous phase behaviours of these diblock copolymers and to specifically identify formulations that were able to generate bilayered vesicles (polymersomes). Cryogenic transmission electron microscopy (cryo-TEM) was utilized in order to visualize the morphology of these structures upon aqueous self-assembly of dry polymer films. Nanoscale polymersomes were formed from PEO-b-PCL copolymers over a wide range of PEO weight fractions (fPEO: 0.14-0.27) and PEO molecular weights (0.75-3.8k) after extrusion of aqueous suspensions. Comparative morphology diagrams, which describe the nature of self-assembled structures as a function of diblock copolymer molecular weight and PEO weight fraction, show that in contrast to micron-scale polymersomes, which form only from a limited range of PEO-b-PCL diblock copolymer compositions, a multiplicity of PEO-b-PCL diblock copolymer compositions are able to give rise to nanoscale vesicles. These data underscore that PEO-b-PCL compositions that spontaneously form micron-sized polymersomes, as well as those that have previously been reported to form polymersomes via a cosolvent fabrication system, provide only limited insights into the distribution of PEO-b-PCL diblocks that give rise to nanoscale vesicles. The broad range of polymersome-forming PEO-b-PCL compositions described herein suggest the ability to construct extensive families of nanoscale vesicles of varied bilayer thickness, providing the ability to tune the timescales of vesicle degradation and encapsulant

  17. Design and Synthesis of an 18F-Labeled Version of Phenylethyl Orvinol ([18F]FE-PEO for PET-Imaging of Opioid Receptors

    Directory of Open Access Journals (Sweden)

    Gjermund Henriksen

    2012-09-01

    Full Text Available The semisynthetic oripavine derivative phenethyl orvinol (PEO, a full agonist at opioid receptors (OR, is an attractive structural motif for developing 18F-labeled PET tracers with a high degree of sensitivity for competition between endogenous and exogenous OR-ligands. The target cold reference compound 6-O-(2-fluoroethyl-6-O-desmethylphenylethyl orvinol (FE-PEO was obtained via two separate reaction routes. A three-step synthesis was developed for the preparation of a tosyloxyethyl precursor (TE-TDPEO, the key precursor for a direct, nucleophilic radiofluorination to yield [18F]FE-PEO. The developed radiosynthesis provides the target compound in relevantly high yield and purity, and is adaptable to routine production.

  18. Polystyrene-block-poly(ethylene oxide) copolymers as templates for stacked, spherical large-mesopore silica coatings: dependence of silica pore size on the PS/PEO ratio.

    Science.gov (United States)

    Nisticò, Roberto; Magnacca, Giuliana; Jadhav, Sushilkumar A; Scalarone, Dominique

    2016-01-01

    Large-mesopore silica films with a narrow pore size distribution and high porosity have been obtained by a sol-gel reaction of a silicon oxide precursor (TEOS) and using polystyrene-block-poly(ethylene oxide) (PS-b-PEO) copolymers as templates in an acidic environment. PS-b-PEO copolymers with different molecular weight and composition have been studied in order to assess the effects of the block length on the pore size of the templated silica films. The changes in the morphology of the porous systems have been investigated by transmission electron microscopy and a systematic analysis has been carried out, evidencing the dependence between the hydrophilic/hydrophobic ratio of the two polymer blocks and the size of the final silica pores. The obtained results prove that by tuning the PS/PEO ratio, the pore size of the templated silica films can be easily and finely predicted.

  19. Flocculated Laponite-PEG/PEO dispersions with monovalent salt, a SAXS and simulation study.

    Science.gov (United States)

    Thuresson, A; Segad, M; Turesson, M; Skepö, M

    2016-03-15

    It is well-known that clay can form lamellar structures i.e. tactoids, and recently it has been shown that the tactoid formation is dependent on the platelet diameter. To the authors knowledge, no tactoid formation has been observed for montmorillonite platelets with a diameter less than 60 nm. In this study, small angle X-ray scattering in combination with coarse-grained modeling and molecular dynamics simulations have been utilized to study the sediment of Laponite-polyethylene glycol/polyethylene oxide (PEG/PEO) at elevated salt concentrations (150 mM-1 M). Laponite consists of platelets with a diameter of 25 nm and it is known to have a relatively monodisperse size-distribution. At pH 10, the face of the platelets has a strong negative charge, whereas the rim is slightly positive. Here we show that it is possible to induce tactoids for Laponite if two constraints are fulfilled: (1) addition of high amount of salt such as NaCl, and (2) addition of a neutral polymer such as PEG. The role of the salt is to screen the repulsive interactions between the platelets and the role of the polymer is to bridge the platelets together: hence the loss in configurational entropy of the polymer is counteracted by the gain in attractive polymer-platelet interaction. As the concentration of NaCl and/or PEG increases, the Bragg peak becomes sharper, which is an indication of that larger tactoids are formed. Comparison between Laponite and montmorillonite shows that the interlayer distance between the platelets increases linearly with an increased Debye screening length for both type of clays, whereas the structure peaks of Laponite are broader compared to the montmorillonite. We argue that the main reason to the latter is due to the size of the platelets: (i) smaller platelets are less rotationally restricted and (ii) the effect of positive edge charges is larger when the platelets are smaller, which results in more irregular aggregates. In absence of the polymer, montmorillonite

  20. Synthesis and analysis of Fe3+, Co2+ and Ni2+ : PEO + PVP blended polymer composite films for multifunctional polymer applications

    Indian Academy of Sciences (India)

    K Naveen Kumar; M Vasudeva Reddy; L Vijayalakshmi; Y C Ratnakaram

    2015-08-01

    Blended polymer films of polyethylene oxide + polyvinyl pyrrolidone (PEO + PVP) containing transition metal (TM) ions like Fe3+, Co2+ and Ni2+ have been synthesized by a solution casting method. For these films, structural, thermal, magnetic and optical properties have been studied. X-ray diffraction results reveal the semi-crystalline nature of the polymer films. Thermal stability of the host (undoped) polymer film has been investigated from its thermogravimetric–differential thermal analysis profiles. Raman spectral profiles indicate a complex formation trend owing to the addition of TM ions into the host matrix. Co2+, Fe3+ and Ni2+ ions doped polymer films have revealed ferromagnetism based on their vibrating sample magnetometre profiles. However, the host polymer film has exhibited a paramagnetic nature. Further, ionic conductivities have been calculated using an impedance analyser at different temperatures for all the samples. Among these films, a maximum ionic conductivity ( = 7.5 × 10−6 S cm−1) has been noticed from PEO + PVP : Ni2+ polymer film at 373 K. Emission analysis of Co2+ : PEO + PVP polymer film has exhibited a strong red emission under an UV source and from both PEO + PVP : Fe3+; PEO + PVP: Ni2+, green emissions have commonly been noticed under an UV source. Thus, based on these results, it could be suggested that these TM ions doped PEO + PVP polymer films are found to be potential multifunctional materials for magneto-electric, magneto-optic fields with encouraging electrical, dielectric and optical properties as well as displaying with ferromagnetic nature from the doped films.

  1. PPO/PEO modified hollow fiber membranes improved sensitivity of 3D cultured hepatocytes to drug toxicity via suppressing drug adsorption on membranes.

    Science.gov (United States)

    Shen, Chong; Meng, Qin; He, Wenjuan; Wang, Qichen; Zhang, Guoliang

    2014-11-01

    The three dimensional (3D) cell culture in polymer-based micro system has become a useful tool for in vitro drug discovery. Among those polymers, polysulfone hollow fiber membrane (PSf HFM) is commonly used to create a microenvironment for cells. However, the target drug may adsorb on the polymeric surface, and this elicits negative impacts on cell exposure due to the reduced effective drug concentration in culture medium. In order to reduce the drug adsorption, PSf membrane were modified with hydrophilic Pluronic (PEO-b-PPO-b-PEO) copolymers, L121, P123 and F127 (PEO contents increase from 10%, 30% to 70%), by physical adsorption. As a result, the hydrophilicity of HFMs increased at an order of PSfF127>P123>L121 HFMs. The three modified membrane all showed significant resistance to adsorption of acid/neutral drugs. More importantly, the adsorption of base drugs were largely reduced to an average value of 11% on the L121 HFM. The improved resistance to drug adsorption could be attributed to the synergy of hydrophobic/neutrally charged PPO and hydrophilic PEO. The L121 HFM was further assessed by evaluating the drug hepatotoxicity in 3D culture of hepatocytes. The base drugs, clozapine and doxorubicin, showed more sensitive hepatotoxicity on hepatocytes in L121 HFM than in PSf HFM, while the acid drug, salicylic acid, showed the similar hepatotoxicity to hepatocytes in both HFMs. Our finding suggests that PSf HFM modified by PEO-b-PPO-b-PEO copolymers can efficiently resist the drug adsorption onto polymer membrane, and consequently improve the accuracy and sensitivity of in vitro hepatotoxic drug screening.

  2. External radiation surveillance

    Energy Technology Data Exchange (ETDEWEB)

    Antonio, E.J.

    1995-06-01

    This section of the 1994 Hanford Site Environmental Report describes how external radiation was measured, how surveys were performed, and the results of these measurements and surveys. External radiation exposure rates were measured at locations on and off the Hanford Site using thermoluminescent dosimeters (TLD). External radiation and contamination surveys were also performed with portable radiation survey instruments at locations on and around the Hanford Site.

  3. Polystyrene-block-poly(ethylene oxide) copolymers as templates for stacked, spherical large-mesopore silica coatings: dependence of silica pore size on the PS/PEO ratio

    OpenAIRE

    2016-01-01

    Large-mesopore silica films with a narrow pore size distribution and high porosity have been obtained by a sol–gel reaction of a silicon oxide precursor (TEOS) and using polystyrene-block-poly(ethylene oxide) (PS-b-PEO) copolymers as templates in an acidic environment. PS-b-PEO copolymers with different molecular weight and composition have been studied in order to assess the effects of the block length on the pore size of the templated silica films. The changes in the morphology of the porou...

  4. PEO-b-P4VP/Yttrium Hydroxide Hybrid Nanotubes as Supporter for Catalyst Gold Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Qian Yang; Dao-yong Chen

    2012-01-01

    The adsorption of poly (ethylene oxide)-b-poly(4-vinylpyridine)(PEO-b-P4VP) micelles onto the surface of yttrium hydroxide nanotubes (YNTs) resulted in the hybrid nanotubes with a dense P4VP inner layer and a stretched PEO outer layer surrounding YNTs. The dense P4VP layer was further stabilized by the crosslinking using 1,4-dibromobutane as the crosslinker.Then,the crosslinked hybrid nanotubes (CHNTs) were used as a novel nano supporter for loading the catalyst gold nanoparticles (GNPs) within the crosslinkcd P4VP layer.The resultant GNPs/CHNTs (GNTs loaded on CHNTs) were applied to catalyze the reduction reaction of p-nitrophenol.The results indicate that this novel nano supporter has advantages such as good dispersity in the suspension,high capacity in loading GNPs (0.87 mmol/g),high catalytic activity of the loaded GNPs (12.9 μmol-1min-1),and good reusability of GNTs/CHNTs.

  5. Effect of methyl red dye on dielectric and conductivity properties of PEO/CdCl{sub 2} electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Kamath, Archana; Devendrappa, H., E-mail: dehu2010@gmail.com [Department of Physics, Mangalore University, Mangalagangothri-574199 (India)

    2016-05-06

    In this report the conductivity and dielectric properties of polyethylene oxide-cadmium chloride (PEO/CdCl{sub 2}) polymer electrolyte films doped with an azo dye methyl red (MR) are discussed. The films were prepared by solution casting technique at different concentrations of the dye in PEO/CdCl{sub 2} electrolyte. The thermal behavior, chemical interaction of the dye with the electrolyte and surface morphology were studied by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) respectively. The conductivity and dielectric properties were measured as a function of composition and temperature using complex impedance spectroscopy. The temperature dependent electrical conductivity of the films exhibited Arrhenius type behavior. Conductivity and dielectric results also signify the enhancement in the amorphous phase of the polymer electrolyte dye systems. The value of highest conductivity observed is 1.21x10{sup −4} at 343K and the conductivity of the film was enhanced by a three orders of magnitude.

  6. Effect of methyl red dye on dielectric and conductivity properties of PEO/CdCl2 electrolytes

    Science.gov (United States)

    Kamath, Archana; Devendrappa, H.

    2016-05-01

    In this report the conductivity and dielectric properties of polyethylene oxide-cadmium chloride (PEO/CdCl2) polymer electrolyte films doped with an azo dye methyl red (MR) are discussed. The films were prepared by solution casting technique at different concentrations of the dye in PEO/CdCl2 electrolyte. The thermal behavior, chemical interaction of the dye with the electrolyte and surface morphology were studied by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) respectively. The conductivity and dielectric properties were measured as a function of composition and temperature using complex impedance spectroscopy. The temperature dependent electrical conductivity of the films exhibited Arrhenius type behavior. Conductivity and dielectric results also signify the enhancement in the amorphous phase of the polymer electrolyte dye systems. The value of highest conductivity observed is 1.21x10-4 at 343K and the conductivity of the film was enhanced by a three orders of magnitude.

  7. Optimized performance of quasi-solid-state DSSC with PEO-bismaleimide polymer blend electrolytes filled with a novel procedure.

    Science.gov (United States)

    Lee, Dong Ha; Sun, Kyung Chul; Qadir, Muhammad Bilal; Jeong, Sung Hoon

    2014-12-01

    Dye-sensitized solar cell (DSSC) is an attractive renewable energy technology currently under intense investigation. Electrolyte plays an important role in the photovoltaic performance of the DSSCs and many efforts have been contributed to study different kinds of electrolytes with various characteristics such as liquid electrolytes, polymer electrolytes and so on. In this study, DSSC is developed by using quasi-solid electrolyte and a novel procedure is adopted for filling this electrolyte. The quasi-solid-state electrolyte was prepared by mixing Poly ethylene oxide (PEO) and bismaleimide together and constitution was taken as PEO (15 wt%) at various bismaleimide concentrations (1, 3, 5 wt%). The novel procedure of filling electrolyte consists of three major steps (first step: filling liquid electrolyte, second step: vaporization of liquid electrolyte, third step: refilling quasi-solid-state electrolyte). The electrochemical and photovoltaic performances of DSSCs with these electrolytes were also investigated. The electrochemical impedance spectroscopy (EIS) indicated that TiO2/Dye/electrolyte impedance is reduced and electron lifetime is increased, and consequently efficiency of cell has been improved after using this novel procedure. The photovoltaic power conversion efficiency of 6.39% has been achieved under AM 1.5 simulated sunlight (100 W/cm2) through this novel procedure and by using specified blend of polymers.

  8. Conductividad iónica en nuevos compositos (PEO10(CF3COONa-X % Al2O3

    Directory of Open Access Journals (Sweden)

    Nori Jurado Meneses

    2013-07-01

    Full Text Available To increase the ionic conductivity of solid polymer electrolyte, (PEO10CF3COONa, we formed new composites by adding alumina particles as a filler. We prepared these composites by dissolving them ina liquid solvent, and characterized them through impedance spectroscopy (IS, using a Pt/electrolyte/Pt electrode configuration. The combination of polyethylene oxide (PEO with sodium trifluoroacetate (CF3COONa produced a reduction in resistance of up to two orders of magnitude in Nyquist plots, and up to three orders of magnitude when we added Al2O3 particles at room temperature. DC conductivity concentration graphs show an increase in the ionic conductivity with low alumina concentrations. The new synthesized ionic conductor composite presented conductivity values of 2.00x10-5 Scm-1 at room temperature and of 7.70x10-4 Scm-1 at a temperature of 383 K. Two sections of the conductivity diagrams also evidenced a temperature induced Arrhenius behavior, indicating a thermally activated process. Higher concentrations of Al2O3 induced a Vogel-Tamman-Fulcher (VTF behavior. Conductivity variations produced by Al2O3 concentration are linked to the number of sites involved in ion transport between Al2O3 ionic electrolyte species through Lewis acid-base interactions.

  9. Roles of nonpolar and polar intermolecular interactions in the improvement of the drug loading capacity of PEO-b-PCL with increasing PCL content for two hydrophobic Cucurbitacin drugs.

    Science.gov (United States)

    Patel, Sarthak K; Lavasanifar, Afsaneh; Choi, Phillip

    2009-09-14

    Molecular dynamics (MD) simulation was used to study the roles of nonpolar and polar intermolecular interactions in the improvement of the drug loading capacity of poly(ethylene oxide)-b-poly(epsilon-caprolactone) (PEO-b-PCL) with increasing PCL content for two water insoluble anticancer drugs: Cucurbitacin B (CuB) and Cucurbitacin I (CuI). In particular, random binary mixture models containing 10-12 wt % drug and remaining PEO-b-PCL with three different PCL/PEO (w/w) ratios (0.5, 1, and 2) were used to calculate their Flory-Huggins interaction parameters (chi). The MD simulation results show that, for both CuB and CuI, the computed chi decreases (i.e., affinity increases) with increasing PCL/PEO ratio. Such results are consistent with our experimental observation that increasing the PCL/PEO (w/w) ratio from 1 to 4.8 significantly increases the drug loading capacity of micelles formed by PEO-b-PCL for both drugs. Analysis of the energy data shows that increasing affinity (loading) at higher PCL/PEO ratio is attributed to the increase in favorable polar interactions and to the formation of additional hydrogen bonds (H-bonds) between the drugs and the PCL block rather than to the increase in the hydrophobic characteristics of the diblock copolymer as one would normally expect. In fact, the nonpolar intermolecular interactions became more unfavorable at higher PCL/PEO ratio. Analysis of the radial distribution functions of the model mixtures indicates that at high PCL/PEO ratio, multiple H-bond sites on the PCL block interacted with single H-bond sites on the drug molecules. However, at low PCL/PEO ratio, only single H-bonds formed between various H-bond sites on the drug molecules and those of the PCL and PEO blocks. It seems that formation of H-bonds between multiple H-bond sites on the PCL block and single H-bond sites on the drug molecules is responsible for inducing drug/PEO-b-PCL affinity. The finding also explains the experimental observation that release rates

  10. A combined acidification/PEO flocculation process to improve the lignin removal from the pre-hydrolysis liquor of kraft-based dissolving pulp production process.

    Science.gov (United States)

    Shi, Haiqiang; Fatehi, Pedram; Xiao, Huining; Ni, Yonghao

    2011-04-01

    The presence of lignin impairs the utilization of the hemicelluloses dissolved in the pre-hydrolysis liquor (PHL) of the kraft-based dissolving pulp production process. In this paper, a novel process was developed by combining the acidification and poly ethylene oxide (PEO) flocculation concepts to improve the lignin removal. The results showed that the lignin removal was improved by the addition of PEO to the acidified PHL, particularly at a low pH of 1.5. The main mechanisms involved are the lignin/PEO complex formation and the bridging of the formed complexes. This hypothesis was supported by the turbidity, FTIR and particle size measurements. Interestingly, the hemicelluloses removal from the acidification/PEO flocculation was marginal, which would be beneficial for the down-stream ethanol production from the PHL. Additionally, a process flow diagram was proposed that incorporates this new concept into the existing configuration of kraft-based dissolving pulp production process. Copyright © 2011 Elsevier Ltd. All rights reserved.

  11. Reduction and control of domain spacing by additive inclusion: morphology and orientation effects of glycols on microphase separated PS-b-PEO.

    Science.gov (United States)

    Ghoshal, Tandra; Shaw, Matthew T; Holmes, Justin D; Morris, Michael A

    2015-07-15

    Cylindrical phase polystyrene-b-polyethylene oxide (PS-b-PEO) block copolymer (BCP) was combined with lower molecular weight poly/ethylene glycols at different concentrations and their effect on the microphase separation of BCP thin films were studied. Well-ordered microphase separated, periodic nanostructures were realized using a solvent annealing approach for solution cast thin films. By optimizing solvent exposure time, the nature and concentration of the additives etc. the morphology and orientation of the films can be controlled. The addition of the glycols to PS-b-PEO enables a simple method by which the microdomain spacing of the phase separated BCP can be controlled at dimensions below 50 nm. Most interestingly, the additives results in an expected increase in domain spacing (i.e. pitch size) but in some conditions an unexpected reduction in domain spacing. The pitch size achieved by modification is in the range of 16-31 nm compared to an unmodified BCP system which exhibits a pitch size of 25 nm. The pitch size modification achieved can be explained in terms of chemical structure, solubility parameters, crystallinity and glass transition temperature of the PEO because the additives act as PEO 'stress cracking agents' whereas the PS matrix remains chemically unaffected.

  12. Influence of shear on microbial adhesion to PEO-brushes and glass by convective-diffusion and sedimentation in a parallel plate flow chamber

    NARCIS (Netherlands)

    Roosjen, A; Boks, NP; van der Mei, HC; Busscher, HJ; Norde, W

    2005-01-01

    Microbial adhesion to surfaces often occurs despite high wall shear rates acting on the adhering microorganisms. In this paper, we compare the wall shear rates needed to prevent microbial adhesion to bare glass and poly(ethylene oxide) (PEO)-brush coated glass in a parallel plate flow chamber. Initi

  13. Studies on structural, thermal and AC conductivity scaling of PEO-LiPF6 polymer electrolyte with added ionic liquid [BMIMPF6

    Directory of Open Access Journals (Sweden)

    S. K. Chaurasia

    2015-07-01

    Full Text Available Preparation and characterization of polymer electrolyte films of PEO+10wt.% LiPF6 + xwt.% BMIMPF6 (1-butyl-3-methylimidazolium hexafluorophosphate containing dopant salt lithium hexafluorophosphate (LiPF6 and ionic liquid (BMIMPF6 having common anion PF 6 - are reported. The ionic conductivity of the polymer electrolyte films has been found to increase with increasing concentration of BMIMPF6 in PEO+10 wt.% LiPF6 due to the plasticization effect of ionic liquid. DSC and XRD results show that the crystallinity of polymer electrolyte decreases with BMIMPF6 concentration which, in turn, is responsible for the increase in ionic conductivity. FTIR spectroscopic study shows the complexation of salt and/or ionic liquid cations with the polymer backbone. Ion dynamics behavior of PEO+LiPF6 as well as PEO+LiPF6 + BMIMPF6 polymer electrolytes was studied by frequency dependent conductivity, σ(f measurements. The values σ(f at various temperatures have been analyzed in terms of Jonscher power law (JPL and scaled with respect to frequency which shows universal power law characteristics at all temperatures.

  14. Effects of concentration and temperature on the dynamic behavior of PAA-g-PEO aqueous solutions with different counterion species: a dielectric spectroscopy study.

    Science.gov (United States)

    Liu, Chunyan; Zhao, Kongshuang

    2012-01-19

    Dielectric properties of PAA-g-PEO-7% solutions with different counterions were measured as a function of concentration and temperature over a frequency range of 40 Hz to 110 MHz. After the contribution of electrode polarization effects was subtracted, the dielectric spectra of PAA-g-PEO-7% solutions showed three relaxation processes in the experimental frequency range, named low-, mid-, and high-frequency relaxation. The observed three relaxations were strictly analyzed by using the Cole-Cole relaxation function, and the dielectric parameters (dielectric increment Δε and the relaxation time τ) were obtained. The scaling relation of dielectric increment and relaxation time of high frequency with concentration C(p) were obtained and compared with the predictions of scaling theories. The information on the dynamics and microstructure of PAA-g-PEO-7% was obtained. Using different counterion species, the mid- and high-frequency relaxation mechanisms were attributed to the fluctuation of condensed counterions and free counterions, respectively, and the low-frequency relaxation was considered to be caused by the interface polarization of a complex formed by the hydrogen bonding between carboxylic group of PAA and ether oxygen on the side-chain PEO. In addition, by means of Eyring equation, the thermodynamic parameters, enthalpy change ΔH and entropy change ΔS, of the three relaxations were calculated from the relaxation time and discussed from the microscopic thermodynamical view.

  15. Externally Verifiable Oblivious RAM

    Directory of Open Access Journals (Sweden)

    Gancher Joshua

    2017-04-01

    Full Text Available We present the idea of externally verifiable oblivious RAM (ORAM. Our goal is to allow a client and server carrying out an ORAM protocol to have disputes adjudicated by a third party, allowing for the enforcement of penalties against an unreliable or malicious server. We give a security definition that guarantees protection not only against a malicious server but also against a client making false accusations. We then give modifications of the Path ORAM [15] and Ring ORAM [9] protocols that meet this security definition. These protocols both have the same asymptotic runtimes as the semi-honest original versions and require the external verifier to be involved only when the client or server deviates from the protocol. Finally, we implement externally verified ORAM, along with an automated cryptocurrency contract to use as the external verifier.

  16. External Beam Therapy (EBT)

    Science.gov (United States)

    ... Esophageal Cancer Treatment Head and Neck Cancer Treatment Lung Cancer Treatment Prostate Cancer Treatment Brain Tumor Treatment Why is ... Radiation Oncology) Breast Cancer Treatment Esophageal Cancer Treatment Lung Cancer Treatment Images related to External Beam Therapy (EBT) Sponsored ...

  17. MALIGNANT EXTERNAL OTITIS

    OpenAIRE

    Massoud Moghaddam

    1993-01-01

    Two case reports of malignant external otitis in the elderly diabetics and their complications and management with regard to our experience at Amir Alam Hospital, Department of ENT will be discussed here.

  18. Checklists for external validity

    DEFF Research Database (Denmark)

    Dyrvig, Anne-Kirstine; Kidholm, Kristian; Gerke, Oke;

    2014-01-01

    RATIONALE, AIMS AND OBJECTIVES: The quality of the current literature on external validity varies considerably. An improved checklist with validated items on external validity would aid decision-makers in judging similarities among circumstances when transferring evidence from a study setting...... to an implementation setting. In this paper, currently available checklists on external validity are identified, assessed and used as a basis for proposing a new improved instrument. METHOD: A systematic literature review was carried out in Pubmed, Embase and Cinahl on English-language papers without time restrictions....... The retrieved checklist items were assessed for (i) the methodology used in primary literature, justifying inclusion of each item; and (ii) the number of times each item appeared in checklists. RESULTS: Fifteen papers were identified, presenting a total of 21 checklists for external validity, yielding a total...

  19. Migration with fiscal externalities.

    Science.gov (United States)

    Hercowitz, Z; Pines, D

    1991-11-01

    "This paper analyses the distribution of a country's population among regions when migration involves fiscal externalities. The main question addressed is whether a decentralized decision making [by] regional governments can produce an optimal population distribution...or a centralized intervention is indispensable, as argued before in the literature.... It turns out that, while with costless mobility the fiscal externality is fully internalized by voluntary interregional transfers, with costly mobility, centrally coordinated transfers still remain indispensable for achieving the socially optimal allocation."

  20. Sen cycles and externalities

    OpenAIRE

    Piggins, Ashley; Salerno, Gillian

    2016-01-01

    It has long been understood that externalities of some kind are responsible for Sen’s (1970) theorem on the impossibility of a Paretian liberal. However, Saari and Petron (2006) show that for any social preference cycle generated by combining the weak Pareto principle and individual decisiveness, every decisive individual must suffer at least one strong negative externality. We show that this fundamental result only holds when individual preferences are strict. Building on their contribution,...

  1. Energy transfer based photoluminescence spectra of (Tb{sup 3+}+ Sm{sup 3+}):PEO+PVP polymer nano-composites with Ag nano-particles

    Energy Technology Data Exchange (ETDEWEB)

    Naveen Kumar, K., E-mail: knaveenphy@gmail.com; Chandra Babu, B.; Buddhudu, S.

    2015-05-15

    Sm{sup 3+}:PEO+PVP, Sm{sup 3+}+Tb{sup 3+}:PEO+PVP and Sm{sup 3+}+Tb{sup 3+}+Ag NPs:PEO+PVP polymer films have successfully been synthesized by a solution casting method. For these polymer films, their XRD, FTIR and RAMAN spectral profiles have been analyzed. Both absorption and photoluminescence spectra have been measured in evaluating their optical properties. The Sm{sup 3+}:PEO+PVP polymer film has displayed a reddish-orange emission at 600 nm under an UV lamp and its absorption and emission spectra have also been measured to evaluate its optical characteristics. A reddish-orange emission at 600 nm ({sup 4}G{sub 5/2}→ {sup 6}H{sub 7/2}) of Sm{sup 3+} has been measured for which lifetime has also been evaluated suitably. The Photoluminescence efficiency of Sm{sup 3+} ion has been enhanced due to the addition of Tb{sup 3+} by means of an energy transfer process. The energy transfer mechanism, from Tb{sup 3+} to Sm{sup 3+} has been explained. In Ag nano-filler embedded in Tb{sup 3+}+Sm{sup 3+}:PEO+PVP polymer system, a different energy transfer process which exists between Ag nano-particles and Sm{sup 3+} ions also taking place in the polymer matrix has been identified. From these results, these films could be suggested as potential reddish-orange luminescent optical materials.

  2. A pH-and temperature-sensitive macrocyclic graft copolymer composed of PEO ring and multi-poly(2-(dimethylamino) ethyl methacrylate) lateral chains

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A novel method for the synthesis of macrocyclic graft copolymers was developed through combination of anionic ring-opening polymerization (AROP) and atom transfer radical polymerization (ATRP).A linear α,ω-dihydroxyl poly(ethylene oxide) with pendant acetal protected hydroxyl groups (l-poly(EO-co-EEGE)) was prepared first by the anionic copolymerization of ethylene oxide (EO) and ethoxyethyl glycidyl ether (EEGE).Then l-poly(EO-co-EEGE) was cyclized.The crude cyclized product containing the linear byproduct was hydrolyzed and purified by being treated with α-CD.The pure cyclic copolymer [c-poly(EO-co-Gly)] was esterified by reaction with 2-bromoisobutyryl bromide,and then used as ATRP macroinitiators to initiate polymerization of 2-(dimethylamino) ethyl methacrylate (DMAEMA),and a series of pH-and temperature-sensitive macrocyclic graft copolymers composed of a hydrophilic PEO as the ring and PDMAEMA as side chains (c-PEO-g-PDMAEMA) were obtained.The behavior of pH-and temperature-sensitive macrocyclic copolymers was studied in aqueous solution by fluorescence and dynamic light scattering (DLS).The critical micellization pH values of macrocyclic graft copolymers and their corresponding linear graft copolymers (l-PEO-g-PDMAEMA) were measured.Under the same conditions,the cyclic graft copolymer with the shorter side chains gave the higher critical micellization pH value.The c-PEO-g-PDMAEMA showed the lower critical micellization pH value than the corresponding l-PEO-g-PDMAEMA.The average hydrodynamic diameters (Dh) of the micelles were measured by DLS with the variation of the aqueous solution pH value and temperature.

  3. Stability of silicon and titanium carbide suspensions in electrolyte, poly(ethylene oxide), and PEO-surfactant solutions.

    Science.gov (United States)

    Barany, Sandor; Eremenko, Boris V; Malysheva, Mariya L

    2004-07-01

    It has been shown that the coagulation values of counterions for SiC and TiC suspensions with particle radius from 0.5 to 5 microm obey a z(2.5-3.5) law and there is an insufficient change in the critical concentration of 1-1 electrolytes (CCE) when the surface potential of particles increases more than two times. Also, the CCE values hardly depend on the position of counterions in the lyotropic sequence. This is explained by aggregation of SiC and TiC particles at a secondary minimum, which is proved by calculations of the potential curves of interparticle interactions using the DLVO theory. The adsorption of poly(ethylene oxide) on the surfaces studied does not cause--in contradiction to dispersions with smaller particles--an unlimited growth in the stability of suspensions. This is due to the aggregation of large particles with adsorbed PEO, as in polymer-free dispersions, under barrierless conditions in which the coordinates of the secondary minimum are determined by superposition of molecular attractive forces and steric repulsive forces of adsorbed polymeric chains, without a contribution from the electric repulsion term. PEO-anionic surfactant complexes possess higher stabilizing capacity compared to the individual components of the mixture. Our results show that the adsorbed polymer layers may hinder the aggregation both in the primary and in the secondary minimum for not very large particles only, the critical size of which depends on the dispersed phase nature and the molecular mass of the polymer.

  4. Environmental external effects from wind power based on the EU ExternE methodology

    DEFF Research Database (Denmark)

    Ibsen, Liselotte Schleisner; Nielsen, Per Sieverts

    1998-01-01

    The European Commission has launched a major study project, ExternE, to develop a methodology to quantify externalities. A “National Implementation Phase”, was started under the Joule II programme with the purpose of implementing the ExternE methodology in all member states. The main objective...

  5. Conductivity enhancement in K{sup +}-ion conducting dry Solid Polymer Electrolyte (SPE): [PEO: KNO{sub 3}]: A consequence of KI dispersal and nano-ionic effect

    Energy Technology Data Exchange (ETDEWEB)

    Kesharwani, Priyanka; Sahu, Dinesh K.; Mahipal, Y.K.; Agrawal, R.C., E-mail: rakesh_c_agrawal@yahoo.co.in

    2017-06-01

    Flexible films of dry Solid Polymer Electrolytes (SPEs): [PEO: KNO{sub 3}] in varying salt concentrations have been hot-press cast. Salt concentration dependent conductivity study revealed two SPE films: [95PEO: 5KNO{sub 3}] and [70PEO: 30KNO{sub 3}] exhibiting relatively higher room temperature conductivity (σ{sub rt}) ∼ 2.76 × 10{sup -7} S/cm and ∼4.31 × 10{sup -7} S/cm respectively. In order to increase σ{sub rt} further, two strategies have been adopted. Firstly, fractional amount of KI has been dispersed as IInd-phase active filler into above two SPE film compositions which acted as Ist-phase host and Composite Polymer Electrolyte (CPE) films were hot-press cast. Filler particle concentration dependent conductivity study identified CPE films: [(95PEO: 5KNO{sub 3}) + 7KI] and [(70PEO: 30KNO{sub 3}) + 10 KI] as optimum conducting films with σ{sub rt} ∼ 6.15 × 10{sup -6} S/cm and ∼3.98 × 10{sup -6} S/cm respectively. σ{sub rt}-enhancement of approximately an order of magnitude was achieved by this approach. In second approach, dry powder mixture of (KNO{sub 3} + KI), in ratio that of above two CPE films, were subjected to high energy ball-milling separately for different durations prior to casting the films again. The conductivity measurements as a function of milling time identified CPE films: [(95PEO: 5KNO{sub 3}) + 7KI] and [(70PEO: 30KNO{sub 3}) + 10 KI] in which two respective (KNO{sub 3} + KI) ratios milled for 4- and 6-h, exhibited almost similar value of σ{sub rt} ∼ 2.09 × 10{sup -5} S/cm. This approach increased σ{sub rt} further by ∼3–6 fold. The reason attributed for this has been Nano–ionic effect introduced at the interphase boundaries between KNO{sub 3} and KI, as a consequence of milling. These films have been referred to as milled CPE films. Subsequently, all the optimum conducting SPE and CPE (unmilled/milled) films were subjected to various characterization studies in order to evaluate their utility in potential All

  6. Externality or sustainability economics?

    Energy Technology Data Exchange (ETDEWEB)

    Bergh, Jeroen C.J.M. van den [ICREA, Barcelona (Spain); Department of Economics and Economic History and Institute for Environmental Science and Technology, Universitat Autonoma de Barcelona (Spain)

    2010-09-15

    In an effort to develop 'sustainability economics' Baumgaertner and Quaas (2010) neglect the central concept of environmental economics-'environmental externality'. This note proposes a possible connection between the concepts of environmental externality and sustainability. In addition, attention is asked for other aspects of 'sustainability economics', namely the distinction weak/strong sustainability, spatial sustainability and sustainable trade, distinctive sustainability policy, and the ideas of early 'sustainability economists'. I argue that both sustainability and externalities reflect a systems perspective and propose that effective sustainability solutions require that more attention is given to system feedbacks, notably other-regarding preferences and social interactions, and energy and environmental rebound. The case of climate change and policy is used to illustrate particular statements. As a conclusion, a list of 20 insights and suggestions for research is offered. (author)

  7. Metasurface external cavity laser

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Luyao, E-mail: luyaoxu.ee@ucla.edu; Curwen, Christopher A.; Williams, Benjamin S. [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); California NanoSystems Institute, University of California, Los Angeles, California 90095 (United States); Hon, Philip W. C.; Itoh, Tatsuo [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); Chen, Qi-Sheng [Northrop Grumman Aerospace Systems, Redondo Beach, California 90278 (United States)

    2015-11-30

    A vertical-external-cavity surface-emitting-laser is demonstrated in the terahertz range, which is based upon an amplifying metasurface reflector composed of a sub-wavelength array of antenna-coupled quantum-cascade sub-cavities. Lasing is possible when the metasurface reflector is placed into a low-loss external cavity such that the external cavity—not the sub-cavities—determines the beam properties. A near-Gaussian beam of 4.3° × 5.1° divergence is observed and an output power level >5 mW is achieved. The polarized response of the metasurface allows the use of a wire-grid polarizer as an output coupler that is continuously tunable.

  8. PEO-surfactant Assisted Alcothermal or Hydrothermal Synthesis of Hierarchically Mesoporous Titania Materials%PEO-表面活性剂辅助醇热或水热合成分级介孔氧化钛材料

    Institute of Scientific and Technical Information of China (English)

    任铁真; 袁忠勇; 苏宝连

    2007-01-01

    在烷基聚乙烯氧化物(PEO)表面活性剂存在下采用水热或醇热方法合成出了介孔氧化钛,并与无模板体系室温溶胶-凝胶制备的介孔氧化钛进行了比较.这些不同方法制备的氧化钛的结构和特性及形成机理都有明显的不同.在酸性水溶液介质中可合成出双结晶(锐钛矿和板钛矿)结构的、热稳定的、介孔氧化钛,而在醇介质中合成出具有内部大孔结构的介孔氧化钛,其中的介孔是无序分布的呈蠕虫状、由锐钛矿相的氧化钛纳米颗粒聚集形成.无模板溶胶-凝胶制备的介孔氧化钛在焙烧后可得到孔分布11.2 nm的不规则介孔洞.对表面活性剂在介孔结构氧化钛合成中的作用进行了讨论.%Mesoporous titanias have been synthesized by either hydrothermal or alcothermal method in the presence of alkyl poly(ethylene oxide) (PEO) surfactants, and compared with those prepared by template-free room-temperature sol-gel route. The structures and properties of these titania materials are quite different, as well as their formation mechanisms. Thermostable mesoporous titanias with bicrystlline (anatase and brookite)structure were synthesized in acidic aqueous media. Mesoporous titanias with an interior macroporous structure were prepared in ethanol media, in which the mesopores were disordered, wormhole-like, formed by the agglomeration of titania nanoparticles with anatase phase. Narrow pore size distribution at 11.2 nm of irregular mesovoids was obtained in the template-free sol-gel prepared titania after calcination. The role of surfactant templates in the synthesis of mesostructured titanias is discussed.

  9. Stochastic Control - External Models

    DEFF Research Database (Denmark)

    Poulsen, Niels Kjølstad

    2005-01-01

    This note is devoted to control of stochastic systems described in discrete time. We are concerned with external descriptions or transfer function model, where we have a dynamic model for the input output relation only (i.e.. no direct internal information). The methods are based on LTI systems...

  10. Productivity Change and Externalities

    DEFF Research Database (Denmark)

    Kravtsova, Victoria

    2014-01-01

    firms and the economy as a whole. The approach used in the current research accounts for different internal as well as external factors that individual firms face and evaluates the effect on changes in productivity, technology as well as the efficiency of domestic firms. The empirical analysis focuses...... change in different types of firms and sectors of the economy...

  11. Multiple external root resorption.

    Science.gov (United States)

    Yusof, W Z; Ghazali, M N

    1989-04-01

    Presented is an unusual case of multiple external root resorption. Although the cause of this resorption was not determined, several possibilities are presented. Trauma from occlusion, periodontal and pulpal inflammation, and resorption of idiopathic origin are all discussed as possible causes.

  12. Human mitochondrial DNA deletions associated with mutations in the gene encoding Twinkle, a phage T7 gene 4-like protein localized in mitochondria.

    Science.gov (United States)

    Spelbrink, J N; Li, F Y; Tiranti, V; Nikali, K; Yuan, Q P; Tariq, M; Wanrooij, S; Garrido, N; Comi, G; Morandi, L; Santoro, L; Toscano, A; Fabrizi, G M; Somer, H; Croxen, R; Beeson, D; Poulton, J; Suomalainen, A; Jacobs, H T; Zeviani, M; Larsson, C

    2001-07-01

    The gene products involved in mammalian mitochondrial DNA (mtDNA) maintenance and organization remain largely unknown. We report here a novel mitochondrial protein, Twinkle, with structural similarity to phage T7 gene 4 primase/helicase and other hexameric ring helicases. Twinkle colocalizes with mtDNA in mitochondrial nucleoids. Screening of the gene encoding Twinkle in individuals with autosomal dominant progressive external ophthalmoplegia (adPEO), associated with multiple mtDNA deletions, identified 11 different coding-region mutations co-segregating with the disorder in 12 adPEO pedigrees of various ethnic origins. The mutations cluster in a region of the protein proposed to be involved in subunit interactions. The function of Twinkle is inferred to be critical for lifetime maintenance of human mtDNA integrity.

  13. Investigation of Morphological and Mechanical Properties of PVA/ Aloe barbadensis and PEO/Chitosan Blended Nanofibrous Structures Fabricated by Dual Electrospinning System

    OpenAIRE

    2014-01-01

    Chitosan (CS)/Polyethylene oxide (PEO) and Polyvinyl alcohol (PVA)/ Aloe vera (AVG) based electrospun nanofibers were gathered together by dual electrospinning system. Properties of blended solutions for electrospinning were investigated by measuring viscosity, conductivity and pH values. Morphological characteristics of the nanofibers were analyzed by Scanning Electron Microscopy (SEM). Beadless and uniform nanofibers were obtained through the electrospinning process and the diameters of the...

  14. The Research on the Stability of TiO2,MoO3,PEO Doped Four-member Tungstic Acid Sols

    Institute of Scientific and Technical Information of China (English)

    Kai RAO; Xiang Kai FU; Xiao Ping RAO

    2004-01-01

    The TiO2, MoO3, PEO doped four-member tungstic acid sols were prepared for the first time.The stability of different doped content sols were investigated and optimized with rotational viscometer.The four-member doped tungstic acid sol was very stable which could be stored more than two months at room temperature.The WO3 electrochromic film prepared from this doped four- member tungstic acid sol had excellent performance and longevity of service.

  15. Small angle neutron scattering study on the aggregation behaviour of PEO–PPO–PEO copolymers in the presence of a hydrophobic diol

    Indian Academy of Sciences (India)

    B Bharatiya; V K Aswal; P Bahadur

    2008-11-01

    Small angle neutron scattering (SANS) measurements on aqueous solutions of four polyethylene oxide–polypropylene oxide–polyethylene oxide block copolymers (commercially known as Pluronic®)F88, P85, F127 and P123 in the presence of hydrophobic C14Diol (also known as Surfynol® 104) reveal information on micellization, micellar size and micellar transitions. While most hydrophilic F88 (with least PPO/PEO ratio) remained unimers in water at 30◦ C, other copolymers formed micellar solutions. Surfynol® 104 is sparingly soluble in water to only about ∼ 0.1 wt%, but on addition to pluronic solution, it gets incorporated in the micellar region of block copolymer which leads to increase in aggregation number and transformation of spherical to ellipsoidal micelles. The added diol-induced micellization in F88, though hydrophilic copolymers F88 and F127 did not show any appreciable micellar growth or shape changes as observed for P85 and P123 (which are comparatively more hydrophobic). The SANS results on copolymer pairs with same molecular weight PPO but different % PEO (viz. F88 and P85, F127 and P123) and with same molecular weight PEO but different PPO (F88 and F127) reveal that the copolymer with large PPO/PEO ratio facilitate micellar transition in the presence of diol. An increase in temperature and presence of added electrolyte (sodium chloride) in the solution further enhances these effects. The micellar parameters for these systems were found out using available software and are reported.

  16. The Influence of PEO113-b-PS780 Vesicles on the Corrosion Performance of Carbon Steel in Simulated Pore Solution

    OpenAIRE

    Hu, J; Koleva, D. A.; Breugel, K. van

    2012-01-01

    This study presents the results from a preliminary investigation on the corrosion behavior of carbon steel in cement extract (CE) in the presence of very low concentration (0.0024 wt. %) polymeric nano-aggregates (PEO113-b-PS780 vesicles). Two types of vesicles were studied: vesicles with a CaO-containing core and vesicles with an “empty” core. The results from the electrochemical measurements (Electrochemical Impedance Spectroscopy (EIS) and Potentio-dynamic Polarization (PDP)) indicate that...

  17. Synthesis and Properties of High Strength Thin Film Composites of Poly(ethylene Oxide) and PEO-PMMA Blend with Cetylpyridinium Chloride Modified Clay

    OpenAIRE

    Mohammad Saleem Khan; Sabiha Sultana

    2015-01-01

    Ion-conducting thin film composites of polymer electrolytes were prepared by mixing high MW poly(ethylene oxide) (PEO), poly(methyl methacrylate) (PMMA) as a polymer matrix, cetylpyridinium chloride (CPC) modified MMT as filler, and different content of LiClO4 by using solution cast method. The crystallinity, ionic conductivity (σ), and mechanical properties of the composite electrolytes and blend composites were evaluated by using XRD, AC impedance, and UTM studies, respectively. The modific...

  18. Mechanisms of ionic conduction related to the structure of the gel electrolytes composed of cross-linked PEO matrix; Kakyo PEO wo matrix kokkaku to suru gel denkaishitsu no kozo to ion ido kiko

    Energy Technology Data Exchange (ETDEWEB)

    Aihara, Y.; Arai, S. [Yuasa Corp., Osaka (Japan); Hayamizu, K. [National Institute of Materials and Chemical Research, Tsukuba (Japan); Price, W.

    1998-04-27

    The ionic conduction mechanism of a non-aqueous polymer gel electrolyte based on the matrix of a chemically cross-linked polyethylene oxide is reported. Subjected to experiment in this report is a polyethylene oxide (PEO)/{gamma}-butyrolactone (GBL) base electrolyte . In this electrolyte, GBL is the solvent and LiBF4 is the solute, and cross-linked polyethylene glycol diacrylate serves as the matrix polymer. Concerning this gel electrolyte, ionic conductivity is determined by the AC impedance method, and diffusion coefficients are determined respectively for the polymer, GBL, Li{sup +}, and BF4{sup -} by measuring nuclear magnetic resonance using the field gradient method. In addition , the outcome of measurement by DSC (differential scanning calorimeter) is mentioned. One of the conclusions arrived at after evaluating the above-said results is described below. It is opined that the diffusion of BF4{sup -} and GBL proceeds at a relatively high rate while Li{sup +} moves on interacting with the matrix polymer and subjected to solvent exchange in the adjacent region. 19 refs., 6 figs., 4 tabs.

  19. ExternE transport methodology for external cost evaluation of air pollution

    DEFF Research Database (Denmark)

    Jensen, S. S.; Berkowicz, R.; Brandt, J.

    The report describes how the human exposure estimates based on NERI's human exposure modelling system (AirGIS) can improve the Danish data used for exposure factors in the ExternE Transport methodology. Initially, a brief description of the ExternE Tranport methodology is given and it is summaris...

  20. Polymer-ionic liquid ternary systems for Li-battery electrolytes: Molecular dynamics studies of LiTFSI in a EMIm-TFSI and PEO blend

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Luciano T., E-mail: ltcosta@id.uff.br [Instituto de Química-Departamento de Físico-Química, Universidade Federal Fluminense, Outeiro de São João Batista s/n CEP, 24020-150 Niterói, Rio de Janeiro (Brazil); Sun, Bing; Jeschull, Fabian; Brandell, Daniel [Department of Chemistry—Ångström Laboratory, Uppsala University, P.O. Box 538, SE-751 21 Uppsala (Sweden)

    2015-07-14

    This paper presents atomistic molecular dynamics simulation studies of lithium bis(trifluoromethane)sulfonylimide (LiTFSI) in a blend of 1-ethyl-3-methylimidazolium (EMIm)-TFSI and poly(ethylene oxide) (PEO), which is a promising electrolyte material for Li- and Li-ion batteries. Simulations of 100 ns were performed for temperatures between 303 K and 423 K, for a Li:ether oxygen ratio of 1:16, and for PEO chains with 26 EO repeating units. Li{sup +} coordination and transportation were studied in the ternary electrolyte system, i.e., PEO{sub 16}LiTFSI⋅1.0 EMImTFSI, by applying three different force field models and are here compared to relevant simulation and experimental data. The force fields generated significantly different results, where a scaled charge model displayed the most reasonable comparisons with previous work and overall consistency. It is generally seen that the Li cations are primarily coordinated to polymer chains and less coupled to TFSI anion. The addition of EMImTFSI in the electrolyte system enhances Li diffusion, associated to the enhanced TFSI dynamics observed when increasing the overall TFSI anion concentration in the polymer matrix.

  1. One-step electrochemical growth of a three-dimensional Sn-Ni@PEO nanotube array as a high performance lithium-ion battery anode.

    Science.gov (United States)

    Fan, Xin; Dou, Peng; Jiang, Anni; Ma, Daqian; Xu, Xinhua

    2014-12-24

    Various well-designed nanostructures have been proposed to optimize the electrode systems of lithium-ion batteries for problems like Li(+) diffusion, electron transport, and large volume changes so as to fulfill effective capacity utilization and increase electrode stability. Here, a novel three-dimensional (3D) hybrid Sn-Ni@PEO nanotube array is synthesized as a high performance anode for a lithium-ion battery through a simple one-step electrodeposition for the first time. Superior to the traditional stepwise synthesis processes of heterostructured nanomaterials, this one-step method is more suitable for practical applications. The electrode morphology is well preserved after repeated Li(+) insertion and extraction, indicating that the positive synergistic effect of the alloy nanotube array and 3D ultrathin PEO coating could authentically optimize the current volume-expansion electrode system. The electrochemistry results further confirm that the superiority of the Sn-Ni@PEO nanotube array electrode could largely boost durable high reversible capacities and superior rate performances compared to a Sn-Ni nanowire array. This proposed ternary hybrid structure is proven to be an ideal candidate for the development of high performance anodes for lithium-ion batteries.

  2. Polymer-ionic liquid ternary systems for Li-battery electrolytes: Molecular dynamics studies of LiTFSI in a EMIm-TFSI and PEO blend.

    Science.gov (United States)

    Costa, Luciano T; Sun, Bing; Jeschull, Fabian; Brandell, Daniel

    2015-07-14

    This paper presents atomistic molecular dynamics simulation studies of lithium bis(trifluoromethane)sulfonylimide (LiTFSI) in a blend of 1-ethyl-3-methylimidazolium (EMIm)-TFSI and poly(ethylene oxide) (PEO), which is a promising electrolyte material for Li- and Li-ion batteries. Simulations of 100 ns were performed for temperatures between 303 K and 423 K, for a Li:ether oxygen ratio of 1:16, and for PEO chains with 26 EO repeating units. Li(+) coordination and transportation were studied in the ternary electrolyte system, i.e., PEO16LiTFSI⋅1.0 EMImTFSI, by applying three different force field models and are here compared to relevant simulation and experimental data. The force fields generated significantly different results, where a scaled charge model displayed the most reasonable comparisons with previous work and overall consistency. It is generally seen that the Li cations are primarily coordinated to polymer chains and less coupled to TFSI anion. The addition of EMImTFSI in the electrolyte system enhances Li diffusion, associated to the enhanced TFSI dynamics observed when increasing the overall TFSI anion concentration in the polymer matrix.

  3. SPHERULITIC STRUCTURE AND MORPHOLOGY OF POLY(ETHYLENE SUCCINATE)/POLY(ETHYLENE OXIDE) (PES/PEO) BLENDS WITH ONE-STEP CRYSTALLIZATION

    Institute of Scientific and Technical Information of China (English)

    Jie-ping Liu; Shuan-gai He; Xiao-ping Qiao

    2008-01-01

    The spherlitic structure and morphology development of poly(ethylene succinate)/poly(ethylene oxide) (PES/PEO) blends with one-step crystallization behavior were observed by means of polarizing optical microscope.It was found that the pure PES spherulite in which the adequate quantity of PEO melt existed in the interlamellar regions,and the blending spherulite formed by both PES and PEO lamellae could form simultaneously.When the two types of spherulites contacted with each other the front of the blending spherulite could penetrate into the pure PES spherulite to grow continually.This penetration growth behavior was also observed when the mini-crystal particles of the PES component were formed at lower crystallization temperatures.The kinetics analysis showed that the penetration growth rate was faster than that in the original melt.It was evidenced that the increasing of growth rate and the formation of new growth site should be the typical characteristics of interpenetrated growth in binary crystalline polymer blends.

  4. The External Mind

    DEFF Research Database (Denmark)

    The External Mind: an Introduction by Riccardo Fusaroli, Claudio Paolucci pp. 3-31 The sign of the Hand: Symbolic Practices and the Extended Mind by Massimiliano Cappuccio, Michael Wheeler pp. 33-55 The Overextended Mind by Shaun Gallagher pp. 57-68 The "External Mind": Semiotics, Pragmatism......, Extended Mind and Distributed Cognition by Claudio Paolucci pp. 69-96 The Social Horizon of Embodied Language and Material Symbols by Riccardo Fusaroli pp. 97-123 Semiotics and Theories of Situated/Distributed Action and Cognition: a Dialogue and Many Intersections by Tommaso Granelli pp. 125-167 Building...... Action in Public Environments with Diverse Semiotic Resources by Charles Goodwin pp. 169-182 How Marking in Dance Constitutes Thinking with the Body by David Kirsh pp. 183-214 Ambiguous Coordination: Collaboration in Informal Science Education Research by Ivan Rosero, Robert Lecusay, Michael Cole pp. 215-240...

  5. External-Memory Multimaps

    CERN Document Server

    Angelino, Elaine; Mitzenmacher, Michael; Thaler, Justin

    2011-01-01

    Many data structures support dictionaries, also known as maps or associative arrays, which store and manage a set of key-value pairs. A \\emph{multimap} is generalization that allows multiple values to be associated with the same key. For example, the inverted file data structure that is used prevalently in the infrastructure supporting search engines is a type of multimap, where words are used as keys and document pointers are used as values. We study the multimap abstract data type and how it can be implemented efficiently online in external memory frameworks, with constant expected I/O performance. The key technique used to achieve our results is a combination of cuckoo hashing using buckets that hold multiple items with a multiqueue implementation to cope with varying numbers of values per key. Our external-memory results are for the standard two-level memory model.

  6. The Influence of Viscosity on the Static and Dynamic Properties of PS-PEO Covered Emulsion Drops

    Directory of Open Access Journals (Sweden)

    Damith P. Rozairo

    2016-11-01

    Full Text Available Polymer stabilized emulsions are commonplace in industries ranging from cosmetics and foods to pharmaceuticals. Understanding the physical properties of emulsions is of critical importance to the rapid advancement of industrial applications. In this work, we use a sessile drop geometry to examine the effects of viscosity changes of the surrounding glycerine/water solution on polystyrene-b-polyethylene oxide (PS-PEO covered toluene droplets. In the experiment, emulsion drops are driven by the buoyant force into a smooth mica surface. The drops buckle as they approach the mica, trapping some of the outer fluid which slowly drains out over time. The characteristic time of the drainage process as well as the surface tension was measured as a function of glycerine/water concentration. The surface tension is found to have a minimum at a glycerine concentration of approximately 50% (by weight to water and the drainage rate is shown to be well described by a recent model. The simple experiment not only shows how critical features of emulsion stability can be easily and reliably measured, but also identifies important new features of the drainage process.

  7. Sodium Alginate with PEG/PEO Blends as a Floating Drug Delivery Carrier – In vitro Evaluation

    Directory of Open Access Journals (Sweden)

    Christe Sonia Mary

    2016-09-01

    Full Text Available Purpose: Floating drug delivery system reduces the quantity of drug intake and the risk of overloading the organs with excess drug. Methods: In the present study, we prepared the blends of sodium alginate with polyethylene glycol (PEG and polyethylene oxide (PEO as a matrix, sodium hydrogen carbonate as a pore forming agent, methyl cellulose as a binder and barium chloride containing 10% acetic acid as a hardening agent. Different ratios of pore forming agent to the polymer blend was used to prepare the floating beads with different porosity and morphology. Ciprofloxacin hydrochloride was used as a model drug for the release kinetics studies. Results: The beads were characterized by optical and FESEM microscopy to study the morphology and pore dimensions. The results obtained shows decrease in beads size with increase in the concentration of the pore forming agent. The swelling properties of the beads were found to be in the range of 80% to 125%. The release kinetics of the ciprofloxacin from the beads was measured by UV-Visible spectroscopy at λmax of 278nm and the results shows for highly porous beads. Conclusion: By varying the amount of alginate and pore forming agent the release kinetics is found to get altered. As a result, ciprofloxacin hydrochloride release is found to be sustained from the blended beads.

  8. Investigation of Photocatalytic Properties of NiO/TiO2 Layers Grown via PEO/EPD Method

    Directory of Open Access Journals (Sweden)

    S. Bassaki

    2015-12-01

    Full Text Available Titanium dioxide-nickel oxide porous coatings were synthesized by Plasma Electrolytic Oxidation (PEO/ ElectroPhoretic Deposition (EPD in one step and within a short time. The main purpose of this research was to increase photocatalytic activity of titanium oxide by increasing surface area and coupling of titanium oxide with nickel oxide. Applied voltage effects on phase structure, surface morphology and photocatalytic efficiency of coatings were studied. Phase structure and surface morphology of the synthesized catalysts were investigated by XRD and SEM, respectively. Photocatalytic efficiency of the samples was studied through measuring the decomposition rate of 4-chlorophenol. The results showed that the coatings mainly consisted of anatase and nickel oxide phases whose amounts in coatings increased with the voltage. There was an enhancement of the photocatalytic efficiency in TiO2/NiO composite coatings compared with TiO2 coatings. Besides, there was an optimum amount of NiO to reach maximum photocatalytic efficiently.

  9. Ionic conductivity and dielectric permittivity of PEO-LiClO{sub 4} solid polymer electrolyte plasticized with propylene carbonate

    Energy Technology Data Exchange (ETDEWEB)

    Das, S.; Ghosh, A., E-mail: sspag@iacs.res.in [Department of Solid State Physics, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India)

    2015-02-15

    We have studied ionic conductivity and dielectric permittivity of PEO-LiClO{sub 4} solid polymer electrolyte plasticized with propylene carbonate. Differential scanning calorimetry and X-ray diffraction studies confirm minimum volume fraction of crystalline phase for the polymer electrolyte with 40 wt. % propylene carbonate. The ionic conductivity exhibits a maximum for the same composition. The temperature dependence of the ionic conductivity has been well interpreted using Vogel-Tamman-Fulcher equation. Ion-ion interactions in the polymer electrolytes have been studied using Raman spectra and the concentrations of free ions, ion-pairs and ion-aggregates have been determined. The ionic conductivity increases due to the increase of free ions with the increase of propylene carbonate content. But for higher content of propylene carbonate, the ionic conductivity decreases due to the increase of concentrations of ion-pairs and ion-aggregates. To get further insights into the ion dynamics, the experimental data for the complex dielectric permittivity have been studied using Havriliak–Negami function. The variation of relaxation time with temperature obtained from this formalism follows Vogel-Tamman-Fulcher equation similar to the ionic conductivity.

  10. Ionic relaxation in PEO/PVDF-HFP-LiClO4 blend polymer electrolytes: dependence on salt concentration

    Science.gov (United States)

    Das, S.; Ghosh, A.

    2016-06-01

    In this paper, we have studied the effect of LiClO4 salt concentration on the ionic conduction and relaxation in poly ethylene oxide (PEO) and poly (vinylidene fluoride hexafluoropropylene) (PVDF-HFP) blend polymer electrolytes, in which the molar ratio of ethylene oxide segments to lithium ions (R  =  EO: Li) has been varied between 3 and 35. We have observed two phases in the samples containing low salt concentrations (R  >  9) and single phase in the samples containing high salt concentrations (R  ⩽  9). The scanning electron microscopic images indicate that there exists no phase separation in the blend polymer electrolytes. The temperature dependence of the ionic conductivity shows two slopes corresponding to high and low temperatures and follows Arrhenius relation for the samples containing low salt concentrations (R  >  9). The conductivity relaxation as well as the structural relaxation has been clearly observed at around 104 Hz and 106 Hz for these concentrations of the blended electrolytes. However, a single conductivity relaxation peak has been observed for the compositions with R  ⩽  9. The scaling of the conductivity spectra shows that the relaxation mechanism is independent of temperature, but depends on salt concentration.

  11. Ionic conductivity and dielectric permittivity of PEO-LiClO4 solid polymer electrolyte plasticized with propylene carbonate

    Directory of Open Access Journals (Sweden)

    S. Das

    2015-02-01

    Full Text Available We have studied ionic conductivity and dielectric permittivity of PEO-LiClO4 solid polymer electrolyte plasticized with propylene carbonate. Differential scanning calorimetry and X-ray diffraction studies confirm minimum volume fraction of crystalline phase for the polymer electrolyte with 40 wt. % propylene carbonate. The ionic conductivity exhibits a maximum for the same composition. The temperature dependence of the ionic conductivity has been well interpreted using Vogel-Tamman-Fulcher equation. Ion-ion interactions in the polymer electrolytes have been studied using Raman spectra and the concentrations of free ions, ion-pairs and ion-aggregates have been determined. The ionic conductivity increases due to the increase of free ions with the increase of propylene carbonate content. But for higher content of propylene carbonate, the ionic conductivity decreases due to the increase of concentrations of ion-pairs and ion-aggregates. To get further insights into the ion dynamics, the experimental data for the complex dielectric permittivity have been studied using Havriliak–Negami function. The variation of relaxation time with temperature obtained from this formalism follows Vogel-Tamman-Fulcher equation similar to the ionic conductivity.

  12. Regularization by External Variables

    DEFF Research Database (Denmark)

    Bossolini, Elena; Edwards, R.; Glendinning, P. A.

    2016-01-01

    Regularization was a big topic at the 2016 CRM Intensive Research Program on Advances in Nonsmooth Dynamics. There are many open questions concerning well known kinds of regularization (e.g., by smoothing or hysteresis). Here, we propose a framework for an alternative and important kind of regula...... of regularization, by external variables that shadow either the state or the switch of the original system. The shadow systems are derived from and inspired by various applications in electronic control, predator-prey preference, time delay, and genetic regulation....

  13. Microstructure and Corrosion Resistance of PEO-EPD Composite Film on Mg-9Gd-3Y Magnesium Alloy%Mg-9Gd-3Y镁合金PEO-EPD复合膜层组织结构与耐蚀性研究

    Institute of Scientific and Technical Information of China (English)

    李建平; 王刚; 王萍; 郭永春; 杨忠

    2014-01-01

    The samples of Mg-9Gd-3Y(GW93) Mg alloy were coated with plasma electrolytic oxidation (PEO) ,electrophoretic deposition (EPD) and PEO-EPD processes respectively .Varius coating surface and cross-section morphologies ,organic functional structure and the corresponded corrosion resistance were studied using scanning electron microscopy (SEM ) ,Fourier transform infrared spectrometer , electrochemical and salt spray tests .The effect of voltage and solids fraction in electrodeposition solution on the thickness ,forming rate and corrosion resistance of PEO-EPD composite coating was discussed and compared with those of PEO and EPD only .The results showed that thickness and film forming rate of PEO-EPD composite coating increased with the increase of voltage and solids ,the corrosion rate increased first ,then decreased with the increase of voltage ;however ,the corrosion rate is decreased with the increase of solids .The PEO-EPD composite film consists of ceramic zone ,which formed during PEO process ,and the organic compound zone ,which formed by EPD process .The organic compound zone is bonded closely with the PEO zone in the optimum EPD condition of voltage 70 V ,solids fraction 19% . Compared with PEO coating only ,the corrosion current density of composite coating significantly decreased by two orders of magnitude ,the corrosion potential moved positively more than 200 mV ,and the corrosion resistance improved up to 13 times .%为了提高镁合金的耐蚀性,本文利用扫描电镜分析了Mg-9Gd-3Y(GW93)镁稀土合金表面等离子电解氧化陶瓷层、等离子电解氧化-电泳复合膜层和电泳膜层的表面与纵截面形貌组织,利用傅立叶红外光谱仪(FT-IR)分析了电泳膜层有机官能团类型,用电化学测试手段和盐雾试验方法测试了该合金不同处理膜层的耐蚀性,讨论了电泳电压和固体粉料分数对等离子电解氧化-电泳复合膜层厚度、成膜速率和耐蚀性的影响。

  14. Clinical study of combined treatment with Methycobal and Sodium Tanshinone HA Sulfonate in ophthalmoplegia due to trauma%弥可保联合丹参酮ⅡA磺酸钠治疗由外伤等原因所致眼外肌麻痹的临床观察

    Institute of Scientific and Technical Information of China (English)

    荣华; 崔红平; 周晓东

    2011-01-01

    目的 探讨应用弥可保联合丹参酮ⅡA磺酸钠治疗由外伤等原因所致眼外肌麻痹的临床疗效.方法 观察57例(57眼)眼外肌麻痹(排除炎症,肿瘤,重症肌无力,Graves眼眶病,伴有肌肉及组织嵌顿的眶壁骨折),应用弥可保联合丹参酮ⅡA磺酸钠治疗,对比分析以往采用弥可保治疗53例(53眼)眼外肌麻痹者.结果 弥可保联合丹参酮ⅡA磺酸钠治疗组有效49例(49眼),总有效率85.96% (49/57).对由颅脑外伤或眼眶外伤引起眼外肌麻痹总有效率86.96% (20/23);对由糖尿病、高血压、高血脂、腔隙性脑梗塞等血管性疾病引起眼外肌麻痹总有效率达93.33%(28/30).弥可保对照组有效28例(28眼),总有效率52.83%(28/53).两组疗效差异有统计学意义(P<0.05).结论弥可保联合丹参酮ⅡA磺酸钠治疗眼外肌麻痹能明显提高治愈率.%Objective To investigate the effect of the combined treatment with Methycobal and Sodium Tanshinone ⅡA Sulfonate in ophthalmoplegia due to trauma.Methods 57 cases (57 eyes)of acquired ophthalmoplegia( exclusion inflammation,tumor,myasthenia gravis,Graves ophthalmopathy and orbital blowout fractures with muscle and tissue incarceration)were treated with Methycobal and Sodium Tanshinone ⅡA Sulfonate,compared with 53 patients ( 53 eyes) treated with Methycobal former years.Results In Methycobal and Sodium Tanshinone ⅡA Sulfonate group,efficacy 49 cases,total effective rate was 85.96%,the total effective rate of treatment of ophthalmoplegia caused by craniocerebral trauma or orbital trauma,and ophthalmoplegia related with diabetes,hypertension,hyperlipemia and lacunar infarction were 86.96 % and 93.33 % respectively.In Control group,efficacy 28 cases,total effective rate was 52.83%.The results differed significantly between the two groups.Conclusion Treatment with Methycobal and Sodium Tanshinone ⅡA Sulfonate can increase the cure rate of ophthalmoplegia.

  15. External Measures of Cognition

    Directory of Open Access Journals (Sweden)

    Osvaldo eCairo

    2011-10-01

    Full Text Available The human brain is undoubtedly the most impressive, complex and intricate organ that has evolved over time. It is also probably the least understood, and for that reason, the one that is currently attracting the most attention. In fact, the number of comparative analyses that focus on the evolution of brain size in Homo sapiens and other species has increased dramatically in recent years. In neuroscience, no other issue has generated so much interest and been the topic of so many heated debates as the difference in brain size between socially defined population groups, both its connotations and implications. For over a century, external measures of cognition have been related to intelligence. However, it is still unclear whether these measures actually correspond to cognitive abilities. In summary, this paper must be reviewed with this premise in mind.

  16. A study on microstructure and corrosion resistance of ZrO2-containing PEO coatings formed on AZ31 Mg alloy in phosphate-based electrolyte

    Science.gov (United States)

    Zhuang, J. J.; Guo, Y. Q.; Xiang, N.; Xiong, Y.; Hu, Q.; Song, R. G.

    2015-12-01

    ZrO2-containing ceramic coatings formed on the AZ31 Mg alloy were fabricated in an alkaline electrolyte containing sodium phosphate and potassium fluorozirconate (K2ZrF6) by plasma electrolytic oxidation (PEO). X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) techniques were used to study the phase structure and composition of the coatings. It is indicated that the coatings formed in the K2ZrF6-containing electrolyte were composed of MgO, MgF2 and t-ZrO2. Morphological investigation carried out by scanning electron microscopy (SEM) and stereoscopic microscopy, revealed that the uniformity of coatings increased and roughness of coatings decreased after the addition of K2ZrF6. Electrochemical investigation was achieved by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) test. The results showed that the PEO coating formed in K2ZrF6-containing electrolyte exhibited an improved corrosion resistance than that of the coating formed in K2ZrF6-free electrolyte. In addition, the polarization and EIS tests results both showed that the suitable concentration (2.5 g/l) of K2ZrF6 is of significant ability to improve the corrosion resistance of coatings. However, 5 g/l and 10 g/l K2ZrF6 has a negative effect on improving the corrosion resistance of PEO coatings compared with the coating formed in 2.5 g/l K2ZrF6-containing electrolyte.

  17. Ophthalmoplegia, Dysphonia and Tetraparesis Due to Guillain ...

    African Journals Online (AJOL)

    Guillain-Barre's syndrome (GBS) or inflammatory/post-infectious acute ... It usually begins in the legs and sometimes goes up to the respiratory muscles and cranial ... The gestation is a relative immunological rest period in which autoimmune ...

  18. Release of Bacteriocins from Nanofibers Prepared with Combinations of Poly(D,L-lactide (PDLLA and Poly(Ethylene Oxide (PEO

    Directory of Open Access Journals (Sweden)

    Leon Dicks

    2011-03-01

    Full Text Available Plantaricin 423, produced by Lactobacillus plantarum, and bacteriocin ST4SA produced by Enterococcus mundtii, were electrospun into nanofibers prepared from different combinations of poly(D,L-lactide (PDLLA and poly(ethylene oxide (PEO dissolved in N,N-dimethylformamide (DMF. Both peptides were released from the nanofibers with a high initial burst and retained 88% of their original antimicrobial activity at 37 °C. Nanofibers have the potential to serve as carrier matrix for bacteriocins and open a new field in developing controlled antimicrobial delivery systems for various applications.

  19. PS-b-PEO/Silica Films with Regular and Reverse Mesostructures of Large Characteristic Length Scales Prepared by Solvent Evaporation-Induced Self-Assembly

    Energy Technology Data Exchange (ETDEWEB)

    YU,KUI; BRINKER,C. JEFFREY; HURD,ALAN J.; EISENBERG,ADI

    2000-11-22

    Since the discovery of surfactant-templated silica by Mobil scientists in 1992, mesostructured silica has been synthesized in various forms including thin films, powders, particles, and fibers. In general, mesostructured silica has potential applications, such as in separation, catalysis, sensors, and fluidic microsystems. In respect to these potential applications, mesostructured silica in the form of thin films is perhaps one of the most promising candidates. The preparation of mesostructured silica films through preferential solvent evaporation-induced self-assembly (EISA) has recently received much attention in the laboratories. However, no amphiphile/silica films with reverse mesophases have ever been made through this EISA procedure. Furthermore, templates employed to date have been either surfactants or poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) triblock copolymers, such as pluronic P-123, both of which are water-soluble and alcohol-soluble. Due to their relatively low molecular weight, the templated silica films with mesoscopic order have been limited to relatively small characteristic length scales. In the present communication, the authors report a novel synthetic method to prepare mesostructured amphiphilic/silica films with regular and reverse mesophases of large characteristic length scales. This method involves evaporation-induced self-assembly (EISA) of amphiphilic polystyrene-block-poly(ethylene oxide) (PS-b-PEO) diblock copolymers. In the present study, the PS-b-PEO diblocks are denoted as, for example, PS(215)-b-PEO(100), showing that this particular sample contains 215 S repeat units and 100 EO repeat units. This PS(215)-b-PEO(100) diblock possesses high molecular weight and does not directly mix with water or alcohol. To the authors knowledge, no studies have reported the use of water-insoluble and alcohol-insoluble amphiphilic diblocks as structure-directing agents in the synthesis of mesostructured silica films through

  20. Release of bacteriocins from nanofibers prepared with combinations of poly(d,l-lactide) (PDLLA) and poly(ethylene oxide) (PEO).

    Science.gov (United States)

    Heunis, Tiaan; Bshena, Osama; Klumperman, Bert; Dicks, Leon

    2011-01-01

    Plantaricin 423, produced by Lactobacillus plantarum, and bacteriocin ST4SA produced by Enterococcus mundtii, were electrospun into nanofibers prepared from different combinations of poly(d,l-lactide) (PDLLA) and poly(ethylene oxide) (PEO) dissolved in N,N-dimethylformamide (DMF). Both peptides were released from the nanofibers with a high initial burst and retained 88% of their original antimicrobial activity at 37 °C. Nanofibers have the potential to serve as carrier matrix for bacteriocins and open a new field in developing controlled antimicrobial delivery systems for various applications.

  1. External fixators in haemophilia.

    Science.gov (United States)

    Lee, V; Srivastava, A; PalaniKumar, C; Daniel, A J; Mathews, V; Babu, N; Chandy, M; Sundararaj, G D

    2004-01-01

    External fixators (EF) are not commonly used for patients with haemophilia. We describe the use of EF (Ilizarov, AO- uni- and bi-planar fixators and Charnley clamp) in nine patients (mean age: 19.2 years; range: 9-37) with haemophilia for the following indications - arthrodesis of infected joints, treatment of open fractures and osteoclasis. EF required an average of nine skin punctures [range: 4-17 were maintained for a period of 15 weeks (range: 8-29.5), without regular factor replacement, till bone healing was adequate and were removed with a single dose of factor infusion]. The mean preoperative factor level achieved was 85% (range: 64-102%). Much lower levels were subsequently maintained till wound healing. The average total factor consumption was 430 IU kg(-1) (range: 240-870), administered over a period of 17 days (range: 9-44). There were no major complications related to EF except in a patient who developed inhibitors. In conclusion, EF can be used safely in haemophilic patients who do not have inhibitors and does not require prolonged factor replacement.

  2. Observation of curative effect of compound anisodine combined with dexamethasone by iontophoresis in the treatment of patients with ophthalmoplegia%复方樟柳碱联合地塞米松离子导入治疗眼外肌麻痹的疗效观察

    Institute of Scientific and Technical Information of China (English)

    刘学琴

    2015-01-01

    Objective:To explore the curative effect of compound anisodine combined with dexamethasone by iontophoresis in the treatment of patients with ophthalmoplegia.Methods:72 patients with ophthalmoplegia were selected,and they were divided into the control group and the observation group randomly.The patients in the control group were given promoting blood circulation therapy,and those in the observation group were given the treatment that injected compound anisodine beside superficial temporal artery combined with dexamethasone by iontophoresis.The curative effect of the two groups were compared then.Results:The effective rate of the observation group was 94.4% significantly higher than the control group of 77.7%(P<0.05).Conclusion:There would be well curative effect of compound anisodine combined with dexamethasone by iontophoresis in the treatment of patients with ophthalmoplegia,and also there were no side effects and complications.%目的:探讨复方樟柳碱联合地塞米松离子导入治疗眼外肌麻痹的疗效。方法:收治眼外肌麻痹患者72例(眼),将其随机分为对照组和观察组。对照组进行活血化瘀治疗,观察组进行复方樟柳碱行颞浅动脉旁注射联合地塞米松离子导入治疗。对两组患者的治疗效果进行比较。结果:观察组有效率94.4%明显高于对照组的77.7%(P<0.05)。结论:在眼外肌麻痹的治疗中应用复方樟柳碱联合地塞米松离子导入治疗能够取得良好的治疗效果,且无不良反应和并发症。

  3. Skepticism, contextualism, externalism and modality

    National Research Council Canada - National Science Library

    Ron Wilburn

    2006-01-01

    .... However, because efforts to contextualize externalism via subjunctive conditional analysis court circularity, it is only on an internalistic interpretation that contextualist strategies can even be motivated...

  4. 眼科首诊糖尿病性眼肌麻痹18例临床分析%Newly diagnosdd diabetes in ophthalmology ophthalmoplegia analysis of 18 cases.

    Institute of Scientific and Technical Information of China (English)

    高立

    2011-01-01

    Objective To explore the diplopia as a first diagnosis of diabetes diagnosis, differential diagnosis and pathogenesis.Methods 18 patients underwent routine ophthalmic examinations,including visual acuity,slit lamp microscopy,fundus examination, refraction, as hyperopia close eye position, eye movement, red lens on complex video analysis, eye-B ultrasonic examination, systemic examination,including blood routine, blood glucose, blood lipids, blood biochemistry, thyroid function test, routine head CT.Resuits 18 patients were excluded by clinical examination related to intracranial lesions,cerebrovascular disease, Graves disease, myasthenia gravis, and nasopharyngeal cancer,diagnosed with diabetes.All the monocular disease, which oculomotor nerve palsy in 14 cases,accounting for 77.7% ,no pupil change,abducens nerve palsy in 3 cases,16.7% ,trochlear nerve palsy in 1 case,5.6%.Conclusion With the aging of the population, dietary changes, increasing incidence of diabetes, diabetic ophthalmoplegia caused by an ophthalmologist should focus in order to avoid misdiagnosis and missed diagnosis.%目的 探讨以复视为首诊的糖尿病患者的诊断、鉴别诊断及发病机制.方法 对18例患者行眼科常规检查,包括视力、裂隙灯显微镜检查、眼底检查、屈光检查、视远视近眼位、眼球运动、红镜片法复视像分析、眼B超检查,全身检查包括血常规、血糖、血脂、血生化、甲状腺功能测定,常规行头颅CT.结果 18例患者经临床相关检查排除颅内占位性病变、脑血管病变、Graves病、重症肌无力、鼻咽癌等,确诊为糖尿病.全部为单眼发病,其中动眼神经麻痹者14例(77.7%),均无瞳孔改变,外展神经麻痹者3例(16.7%),滑车神经麻痹者1例(5.6%).结论 随着人口的老龄化,饮食结构改变,糖尿病的发病率越来越高,糖尿病性眼肌麻痹应该引起眼科医生的重视,以免误诊和漏诊.

  5. Effect of drying on the mesoporous structure of sol-gel derived silica with PPO-PEO-PPO template block copolymer.

    Science.gov (United States)

    Pei, Lihua; Kurumada, Ken-Ichi; Tanigaki, Masataka; Hiro, Masahiko; Susa, Kenzo

    2005-04-01

    The effects of drying method on the pore structure of mesoporous silica were studied from the viewpoint of enhancing closed porosity in mesoporous silica. The mesoporous silica was prepared via a sol-gel process using polyethyleneoxide-polypropyleneoxide-polyethyleneoxide (PEO-PPO-PEO) triblock copolymer (Pluronic P123) as the structure-directing template. The closed porosity was evaluated from the apparent mass density of the sample measured by a helium pycnometer. These mesoporous silicas were also characterized by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and nitrogen adsorption. The drying method was shown to be responsible for the finally templated mesoporous structure of the silica. More rapid drying is more preferable for enhancing the closed porosity of the mesoporous silica. The closed pores were formed by immediate immobilization of copolymer molecular assemblies in the silica matrix due to the instant removal of the solvent and solidification at higher temperatures. The drying method, mainly affecting the drying rate, is highly influential on the finally replicated mesoporous structure in silica.

  6. Self-assemblies of γ-CDs with pentablock copolymers PMA-PPO-PEO-PPO-PMA and endcapping via atom transfer radical polymerization of 2-methacryloyloxyethyl phosphorylcholine

    Directory of Open Access Journals (Sweden)

    Jing Lin

    2015-11-01

    Full Text Available Pentablock copolymers PMA-PPO-PEO-PPO-PMA synthesized via atom transfer radical polymerization (ATRP were self-assembled with varying amounts of γ-CDs to prepare poly(pseudorotaxanes (PPRs. When the concentration of γ-CDs was lower, the central PEO segment served as a shell of the micelles and was preferentially bent to pass through the γ-CD cavity to construct double-chain-stranded tight-fit PPRs characterized by a channel-like crystal structure. With an increase in the amount of γ-CDs added, they began to accommodate the poly(methyl acrylate (PMA segments dissociated from the core of the micelles. When more γ-CDs were threaded and slipped over the segments, the γ-CDs were randomly distributed along the pentablock copolymer chain to generate single-chain-stranded loose-fit PPRs and showed no characteristic channel-like crystal structure. All the self-assembly processes of the pentablock copolymers resulted in the formation of hydrogels. After endcapping via in situ ATRP of 2-methacryloyloxyethyl phosphorylcholine (MPC, these single-chain-stranded loose-fit PPRs were transformed into conformational identical polyrotaxanes (PRs. The structures of the PPRs and PRs were characterized by means of 1H NMR, GPC, 13C CP/MAS NMR, 2D 1H NOESY NMR, FTIR, WXRD, TGA and DSC analyses.

  7. Combined Effect of Long Processing Time and Na2SiF6 on the Properties of PEO Coatings Formed on AZ91D

    Science.gov (United States)

    Rehman, Zeeshan Ur; Koo, Bon Heun

    2016-08-01

    In this study, protective ceramic coatings were prepared on AZ91D magnesium alloy by plasma electrolytic oxidation (PEO) to improve the corrosion and mechanical properties of AZ91D magnesium alloy. The process was conducted in silicate-fluoride-based electrolyte solution. It was found that the average micro-hardness of the coating was significantly increased with an increase in the PEO processing time. The highest value of the average micro-hardness ~1271.2 HV was recorded for 60-min processing time. The phase analysis of the coatings indicated that they were mainly composed of Mg2SiO4, MgO, and MgF2 phases. The surface and cross-sectional study demonstrated that porosity was largely reduced with processing time, together with the change in pore geometry from irregular to spherical shape. The results of the polarization test in 3.5 wt.% NaCl solution revealed that aggressive corrosion took place for 5-min sample; however, the corrosion current was noticeably decreased to 0.43 × 10-7 A/cm2 for the 60-min-coated sample. The superior nobility and hardness for long processing time are suggested to be due to the dense and highly thick coating, coupled with the presence of MgF2 phase.

  8. Synergetic effect of TiO2 nano filler additives on conductivity and dielectric properties of PEO/PVP nanocomposite electrolytes for electrochemical cell applications

    Science.gov (United States)

    Koduru, H. K.; Kondamareddy, K. K.; Iliev, M. T.; Marinov, Y. G.; Hadjichristov, G. B.; Karashanova, D.; Scaramuzza, N.

    2017-01-01

    Sodium-ion conducting PEO/PVP blend based solid polymer electrolyte films complexed with NaIO4 salt and nano-sized TiO2 fillers are fabricated by employing a solution casting technique for Na-ion battery applications. Measurements of X-ray diffraction (XRD) and thermogravimetric analysis (TGA) are carried out to investigate the crystallinity and thermal stability of the solid polymer electrolytes. Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) studies are performed to understand the modifications in surface morphological features and to evaluate the size and distribution of dispersed nano-sized TiO2 fillers. The room temperature ionic conductivities of polymer electrolyte films are investigated by impedance analysis in the frequency range 1 MHz - 1 Hz. The nano-sized TiO2 (3 wt%) filled composite electrolyte of ‘PEO/PVP/NaIO4 (10 wt%)’ demonstrates a maximum room temperature conductivity of 9.82 X 10-6 S/cm. The influence of TiO2 filler on conductivity and dielectric properties are presented in this report.

  9. ExternE transport methodology for external cost evaluation of air pollution

    DEFF Research Database (Denmark)

    Jensen, S. S.; Berkowicz, R.; Brandt, J.

    The report describes how the human exposure estimates based on NERI's human exposure modelling system (AirGIS) can improve the Danish data used for exposure factors in the ExternE Transport methodology. Initially, a brief description of the ExternE Tranport methodology is given and it is summaris...... how the methodology has been applied so far in a previous Danish study. Finally, results of a case study are reported. Exposure factors have been calculated for various urban categories in the Greater Copenhagen Area...

  10. ExternE transport methodology for external cost evaluation of air pollution (DK)

    Energy Technology Data Exchange (ETDEWEB)

    Solvang Jensen, S.; Berkowicz, R.; Brandt, J. [National Environmental Research Inst., Dept. of Atmospheric Environment (Denmark); Willumsen, E.; Kristensen, N.B. [COWI (Denmark)

    2004-07-01

    The report describes how the human exposure estimates based on NERI's human exposure modelling system (AiGIS) can improve the Danish data used for exposure factors in the ExternE Transport methodology. Inititally, a brief description of the ExternE Transport methodology is given and it is summarised how the methodology has been applied so far in a previous Danish study. Finally, results of a case study are reported. Exposure factors have been calculated for various urban categories in the Greater Copenhagen Area. (au)

  11. External coating of colonic anastomoses

    DEFF Research Database (Denmark)

    Pommergaard, Hans-Christian; Achiam, Michael Patrick; Rosenberg, Jacob

    2012-01-01

    Colon anastomotic leakage remains both a frequent and serious complication in gastrointestinal surgery. External coating of colonic anastomoses has been proposed as a means to lower the rate of this complication. The aim of this review was to evaluate existing studies on external coating of colonic...

  12. Retrofitting Systems for External Walls

    DEFF Research Database (Denmark)

    Rose, Jørgen

    1997-01-01

    In this report, 9 different external and internal retrofitting systems are analyzed using numerical calculations. The analysis focuses on the thermal bridge effects in the different systems, and on this basis it is discussed whether internal or external retrofitting has the most advantages...

  13. Naised teevad meestele peo

    Index Scriptorium Estoniae

    2005-01-01

    26. aug. kogunesid Rakveres I Eesti meeste tantsupeo üldjuhid, kus kinnitati tantsurühmade registreerimise tähtaeg 15. okt. ja seminaride kalender (24. sept. rühmajuhtide seminar Rakveres, 25. sept. Tallinnas, 1. okt. Pärnus ja 2. okt. Tartus)

  14. PEO Integration Acronym Book

    Science.gov (United States)

    2011-02-01

    Medium ABC Activity-Based Costing ABC Army Battle Command ABCA America-Britain-Canada-Australia Agreement (1964) ABCCC Airborne Battlefield Command...And Control Center ABCDF Aberdeen Chemical Agent Disposal Facility ABCL As-Built Configuration List ABCS Army Battle Command System ABEM Agent Based...Information System ABL Airborne Laser ABL Authorized Basic Load ABM Agent-Based Modeling ABM Anti-Ballistic Missile ABMA Army Ballistic Missile Agency Abn

  15. Performance Targets and External Benchmarking

    DEFF Research Database (Denmark)

    Friis, Ivar; Hansen, Allan; Vámosi, Tamás S.

    Research on relative performance measures, transfer pricing, beyond budgeting initiatives, target costing, piece rates systems and value based management has for decades underlined the importance of external benchmarking in performance management. Research conceptualises external benchmarking...... the conditions upon which the market mechanism is performing within organizations. This paper aims to contribute to research by providing more insight to the conditions for the use of external benchmarking as an element in performance management in organizations. Our study explores a particular type of external...... towards the conditions for the use of the external benchmarks we provide more insights to some of the issues and challenges that are related to using this mechanism for performance management and advance competitiveness in organizations....

  16. External costs related to power production technologies. ExternE national implementation for Denmark

    Energy Technology Data Exchange (ETDEWEB)

    Schleisner, L.; Sieverts Nielsen, P.

    1997-12-01

    The objective of the ExternE National Implementation project has been to establish a comprehensive and comparable set of data on externalities of power generation for all EU member states and Norway. The tasks include the application of the ExternE methodology to the most important fuel cycles for each country as well as to update the already existing results; to aggregate these site- and technology-specific results to more general figures. The current report covers the results of the national implementation for Denmark. Three different fuel cycles have been chosen as case studies. These are fuel cycles for an offshore wind farm and a wind farm on land, a decentralised CHP plant based on natural gas and a decentralised CHP plant based on biogas. The report covers all the details of the application of the methodology to these fuel cycles aggregation to a national level. (au) EU-JOULE 3. 59 tabs., 25 ills., 61 refs.

  17. External fuel thermionic reactor system.

    Science.gov (United States)

    Mondt, J. F.; Peelgren, M. L.

    1971-01-01

    Thermionic reactors are prime candidates for nuclear electric propulsion. The national thermionic reactor effort is concentrated on the flashlight concept with the external-fuel concept as the backup. The external-fuel concept is very adaptable to a completely modular power subsystem which is attractive for highly reliable long-life applications. The 20- to 25-cm long, externally-fueled converters have been designed, fabricated, and successfully tested with many thermal cycles by electrical heating. However, difficulties have been encountered during encapsulation for nuclear heated tests and none have been started to date. These nuclear tests are required to demonstrate the concept feasibility.

  18. Combination of external loads

    Energy Technology Data Exchange (ETDEWEB)

    Frandsen, S.; Tarp Johansen, N.J.; Joergensen, H. [Forskningscenter Risoe, Roskilde (Denmark); Gravesen, H.; Soerensen, S.L. [Carl Bro, Glostrup (Denmark); Pedersen, J. [Elsam Engineering, Fredericia (Denmark); Zorn, R.; Hvidberg Knudsen, M. [DHI Water and Environment, Hoersholm (Denmark); Voelund, P. [Energi E2, Koebenhavn (Denmark)

    2003-09-01

    The project onbectives have been: To improve and consequently opimise the basis for design of offshore wind turbines. This is done through 1) mapping the wind, wave ice and current as well as correlations of these, and 2) by clarifyring how these external conditions transform into loads. A comprehensive effort has been made to get a thorough understanding of the uncertainties that govern the reliability of wind turbines with respect to wind and wave loading. One of the conclusions is that the reliability of wind turbines is generally lower, than the average reliability of building structures that are subject not only to environmental loads, which are very uncertain, but also imposed loads and self weight, which are less uncertain than the environmental loads. The implication is that, at the moment lower load partial safety factors for onshore wind turbines cannot be recommended. For the combination of wind and wave design loads the problem is twofold: 1). A very conservative design will be generated by simply adding the individual wind and wave design loads disregarding the independence of the short-term fluctuations of wind and wave loads. 2). Characteristic values and partial safety factors for wind and wave loads are not defined similarly. This implies that the reliability levels of turbine support structures subject to purely aerodynamic loads and subject to purely hydrodynamic loads are not identical. For the problem of combining aerodynamic design loads and hydrodynamic design loads two results have been obtained in the project: 1). By simple means a site specific wave load safety factor rendering the same safety level for hydrodynamic loads as for aerodynamic loads is derived, and next, by direct square summation of extreme fluctuations, the wind and wave load safety factors are weighted. 2). Under the assumptions that a deep water site is considered and that the wave loading is a fifty-fifty mix of drag and inertia the same wind and wave load safety factor

  19. Influence of PEO and CPAM on the Formation of the Base Paper for Paper Based Friction Material%PEO和CPAM对纸基摩擦材料原纸性能的影响

    Institute of Scientific and Technical Information of China (English)

    陆赵情; 陈杰; 张大坤

    2013-01-01

    The experiment used carbon fiber, chopped Kevlar fiber and aramid pulp, bamboo fiber and sepiolite flocking as raw material to prepare paper based friction material by wet-forming process. Polyethylene oxide ( PEO) and cationic polyacrylamides ( CPAM) were used as chemical additives and the influence of the dosages of PEO and CPAM on furnish dispersion and the paper formation was studied. The results show that the furnish dispersion and the paper formation were the best when the dosages of PEO and CPAM were 0.2% and 0.16% respectively%采用碳纤维、短切芳纶纤维、芳纶浆粕、竹纤维以及海泡石绒为原料,并用抄纸的方法抄造纸基摩擦材料原纸;通过在抄造浆料中添加聚氧化乙烯(PEO)和阳离子聚丙烯酰胺(CPAM),探究了PEO和CPAM对浆料分散性能和纸张匀度和抗张强度的影响.结果表明,PEO对浆料有良好的分散作用,CPAM对纸张有很好的增强效果,当PEO用量为0.2%、CPAM用量为0.16%时,浆料分散效果最好,成纸的匀度最高.

  20. External costs related to power production technologies. ExternE national implementation for Denmark

    Energy Technology Data Exchange (ETDEWEB)

    Schleisner, L.; Sieverts Nielsen, P. [eds.

    1997-12-01

    The objective of the ExternE National Implementation project has been to establish a comprehensive and comparable set of data on externalities of power generation for all EU member states and Norway. The tasks include the application of the ExternE methodology to the most important fuel cycles for each country as well as to update the already existing results, to aggregate these site- and technology-specific results to more general figures. The current report covers the detailed information concerning the ExternE methodology. Importance is attached to the computer system used in the project and the assessment of air pollution effects on health, materials and ecological effects. Also the assessment of global warming damages are described. Finally the report covers the detailed information concerning the national implementation for Denmark for an offshore wind farm and a wind farm on land, a decentralised CHP plant based on natural gas and a decentralised CHP plant base on biogas. (au) EU-JOULE 3. 79 tabs., 11 ills., 201 refs.

  1. Externality and burnout among dentists.

    Science.gov (United States)

    St-Yves, A; Freeston, M H; Godbout, F; Poulin, L; St-Amand, C; Verret, M

    1989-12-01

    This study investigates the relationship between burnout as measured by the Maslach Burnout Inventory and locus of control as measured by the Adult Nowicki-Strickland Internal-External Locus of Control (ANS-IE) for 82 dentists. Significant Pearson correlations between two Maslach subscales and locus of control show Personal Accomplishment to be negatively associated -.31 and Emotional Exhaustion to be positively correlated .21 to externality.

  2. Relatie interne en externe audit

    OpenAIRE

    Ghys, Emelie

    2011-01-01

    In het eerste hoofdstuk wordt de probleemstelling van deze eindverhandeling besproken. Interne en externe audit worden de laatste jaren internationaal en nationaal meer en meer erkend in het bedrijfsleven. Aanleiding voor de toenemende belangstelling van de interne en externe auditfunctie zijn de verschillende boekhoudschandalen rond corporate governance of deugdelijk bestuur. Deze financiële mislukkingen leidden wereldwijd tot diverse wetten, nieuwe regels en verbeterde standaarden om zo een...

  3. Performance Targets and External Benchmarking

    DEFF Research Database (Denmark)

    Friis, Ivar; Hansen, Allan; Vámosi, Tamás S.

    as a market mechanism that can be brought inside the firm to provide incentives for continuous improvement and the development of competitive advances. However, whereas extant research primarily has focused on the importance and effects of using external benchmarks, less attention has been directed towards...... towards the conditions for the use of the external benchmarks we provide more insights to some of the issues and challenges that are related to using this mechanism for performance management and advance competitiveness in organizations....

  4. Parallel External Memory Graph Algorithms

    DEFF Research Database (Denmark)

    Arge, Lars Allan; Goodrich, Michael T.; Sitchinava, Nodari

    2010-01-01

    In this paper, we study parallel I/O efficient graph algorithms in the Parallel External Memory (PEM) model, one o f the private-cache chip multiprocessor (CMP) models. We study the fundamental problem of list ranking which leads to efficient solutions to problems on trees, such as computing lowest...... an optimal speedup of ¿(P) in parallel I/O complexity and parallel computation time, compared to the single-processor external memory counterparts....

  5. External Costs Related to Power Production Technologies

    DEFF Research Database (Denmark)

    Ibsen, Liselotte Schleisner; Nielsen, Per Sieverts

    1997-01-01

    The European Commission has launched a major study project, ExternE, to develop a methodology to quantify externalities. A “National Implementation Phase”, was started under the Joule II programme with the purpose of implementing the ExternE methodology in all member states. The main objective...

  6. External Costs Related to Power Production Technologies

    DEFF Research Database (Denmark)

    Ibsen, Liselotte Schleisner; Nielsen, Per Sieverts

    1997-01-01

    The European Commission has launched a major study project, ExternE, to develop a methodology to quantify externalities. A “National Implementation Phase”, was started under the Joule II programme with the purpose of implementing the ExternE methodology in all member states. The main objective of...

  7. Measuring geographical accessibility to palliative and end of life (PEoLC) related facilities: a comparative study in an area with well-developed specialist palliative care (SPC) provision.

    Science.gov (United States)

    Pearson, Clare; Verne, Julia; Wells, Claudia; Polato, Giovanna M; Higginson, Irene J; Gao, Wei

    2017-01-26

    Geographical accessibility is important in accessing healthcare services. Measuring it has evolved alongside technological and data analysis advances. High correlations between different methods have been detected, but no comparisons exist in the context of palliative and end of life care (PEoLC) studies. To assess how geographical accessibility can affect PEoLC, selection of an appropriate method to capture it is crucial. We therefore aimed to compare methods of measuring geographical accessibility of decedents to PEoLC-related facilities in South London, an area with well-developed SPC provision. Individual-level death registration data in 2012 (n = 18,165), from the Office for National Statistics (ONS) were linked to area-level PEoLC-related facilities from various sources. Simple and more complex measures of geographical accessibility were calculated using the residential postcodes of the decedents and postcodes of the nearest hospital, care home and hospice. Distance measures (straight-line, travel network) and travel times along the road network were compared using geographic information system (GIS) mapping and correlation analysis (Spearman rho). Borough-level maps demonstrate similarities in geographical accessibility measures. Strong positive correlation exist between straight-line and travel distances to the nearest hospital (rho = 0.97), care home (rho = 0.94) and hospice (rho = 0.99). Travel times were also highly correlated with distance measures to the nearest hospital (rho range = 0.84-0.88), care home (rho = 0.88-0.95) and hospice (rho = 0.93-0.95). All correlations were significant at p < 0.001 level. Distance-based and travel-time measures of geographical accessibility to PEoLC-related facilities in South London are similar, suggesting the choice of measure can be based on the ease of calculation.

  8. The role of cathodic current in PEO of aluminum: Influence of cationic electrolyte composition on the transient current-voltage curves and the discharges optical emission spectra

    Science.gov (United States)

    Rogov, A. B.; Shayapov, V. R.

    2017-02-01

    In this paper, the influence of cationic electrolytes composition on electrical and optical responses of plasma electrolytic oxidation process of A1050 aluminum alloy under alternating polarization is considered. The electrolytes consist of 0.1 M boric acid with addition of one of the following hydroxides: LiOH, NaOH, KOH, tetraethylammonium hydroxide, Ca(OH)2 up to pH value 9.2. Coatings microstructure, elemental and phase compositions were studied by SEM, EDS and XRD. It was shown that the hysteresis of anodic current-voltage curve (specific feature of "Soft sparking" PEO) was clear observed in the presence of sodium and potassium cations. It was found that composition of microdischarges plasma is also affected by the nature of the cations. It was shown that there are a number of reciprocal processes, which take place under anodic and cathodic polarization.

  9. Synthesis and Solution Properties of Double Hydrophilic Poly(ethylene oxide-block-poly(2-ethyl-2-oxazoline (PEO-b-PEtOx Star Block Copolymers

    Directory of Open Access Journals (Sweden)

    Felix H. Schacher

    2013-09-01

    Full Text Available We demonstrate the synthesis of star-shaped poly(ethylene oxide-block-poly(2-ethyl-2-oxazoline [PEOm-b-PEtOxn]x block copolymers with eight arms using two different approaches, either the “arm-first” or the “core-first” strategy. Different lengths of the outer PEtOx blocks ranging from 16 to 75 repeating units were used, and the obtained materials [PEO28-b-PEtOxx]8 were characterized via size exclusion chromatography (SEC, nuclear magnetic resonance spectroscopy (NMR, and Fourier-transform infrared spectroscopy (FT-IR measurements. First investigations regarding the solution behavior in water as a non-selective solvent revealed significant differences. Whereas materials synthesized via the “core-first” method seemed to be well soluble (unimers, aggregation occurred in the case of materials synthesized by the “arm-first” method using copper-catalyzed azide-alkyne click chemistry.

  10. Experimental and theoretical study of bifunctionalized PEO–PPO–PEO triblock copolymers with applications as dehydrating agents for heavy crude oil

    Directory of Open Access Journals (Sweden)

    César A. Flores-Sandoval

    2017-03-01

    Full Text Available A series of α,ω-diamines of polyoxyethylene–polyoxypropylene–polyoxyethylene (POE–POP–POE triblock copolymer was synthesized and experimentally evaluated as dewatering agents for heavy crude oil. A quantitative structure–activity relationship (QSAR study of the effect of the secondary amine structure over the yield of nucleophilic substitution reactions with α,ω-ditosylate ester of PEO–PPO–PEO triblock copolymer was performed exclusively at the DFT level. Multiple linear regression (MLR analysis including softness or hardness parameters gave R2 = 0.9062, producing an equation with an acceptable rm(test2 value. Furthermore, in order to understand the physicochemical interaction between the functionalizing copolymers and water, QSAR models based on AM1 semiempirical and DFT (B3LYP functional descriptors were carried out for comparative purposes. For the MLR analysis at the AM1 level, R2 = 0.9058, whereas at the DFT level, R2 = 0.9879. 2-(Methylaminoethanol was employed to evaluate the equations obtained. The residual of the logERcalc SN2 reaction was −0.0043, showing a good correlation with experimental efficiency. Regarding water removal efficiency, the residuals of logWRcalc at the AM1 and DFT levels were of 0.0220 and 0.0041, respectively. Even though, DFT produced a better correlation, a QSAR study at the AM1 level could be employed to study the behavior of α,ω-diamines of PEO–PPO–PEO triblock copolymer and to destabilize water/oil emulsions, with a computational cost relatively low compared to DFT calculations.

  11. Missing osteoconductive effect of a resorbable PEO/PBT copolymer in human bone defects: a clinically relevant pilot study with contrary results to previous animal studies.

    Science.gov (United States)

    Roessler, M; Wilke, A; Griss, P; Kienapfel, H

    2000-01-01

    PEO/PBT 70/30 (POLYACTIVE(R) 70/30), a degradable porous copolymer with elastic properties, was found to be osteoconductive in many animal studies. The aim of this study was to determine the osteoconductive effect in a human paired control iliac defect model. In seven patients undergoing anterior spinal interbody fusion surgery, two bicortical iliac defects for autograft harvesting were created. The defect size was identical for both defects measuring about 40 x 15 mm (group I). One defect was filled with the degradable implants, whereas the remaining one was left untreated as a control. The defect site for treatment was chosen randomly. In three further patients, only one defect measuring about 40 x 35 mm was created (group II). All patients were examined clinically and radiologically by spiral-CT after 1, 6, 12, 24, and 52 weeks. Three-dimensional reconstructions as well as CT-volumetric measurements using 1 mm sections were used as evaluation methods. In group I, a two-tailed paired t-test showed that the treated defects had significantly less formation of new bone than the untreated ones (p < 0.05 after 12 weeks, p < 0.01 after 52 weeks). Also, in group II, not much bone ingrowth could be observed. The histological evaluation of one patient in group I revealed no bone within the pores, and a fibrous layer between bone and implant was always present. Therefore, PEO/PBT 70/30 cannot be recommended as a bone substitute for clinical use. Differences in bone regeneration between humans and certain animal species as well as inapplicable defect models in previous animal studies are discussed as possible reasons for the failure.

  12. Thermodynamic cost of external control

    Science.gov (United States)

    Barato, Andre C.; Seifert, Udo

    2017-07-01

    Artificial molecular machines are often driven by the periodic variation of an external parameter. This external control exerts work on the system of which a part can be extracted as output if the system runs against an applied load. Usually, the thermodynamic cost of the process that generates the external control is ignored. Here, we derive a refined second law for such small machines that include this cost, which is, for example, generated by free energy consumption of a chemical reaction that modifies the energy landscape for such a machine. In the limit of irreversible control, this refined second law becomes the standard one. Beyond this ideal limiting case, our analysis shows that due to a new entropic term unexpected regimes can occur: the control work can be smaller than the extracted work and the work required to generate the control can be smaller than this control work. Our general inequalities are illustrated by a paradigmatic three-state system.

  13. Leveraging External Sources of Innovation

    DEFF Research Database (Denmark)

    West, Joel; Bogers, Marcel

    2014-01-01

    This paper reviews research on open innovation that considers how and why firms commercialize external sources of innovations. It examines both the “outside-in” and “coupled” modes of open innovation. From an analysis of prior research on how firms leverage external sources of innovation...... cited work beyond those journals. A review of 291 open innovation-related publications from these sources shows that the majority of these articles indeed address elements of this inbound open innovation process model. Specifically, it finds that researchers have front-loaded their examination...... external innovations create value rather than how firms capture value from those innovations. Finally, the interaction phase considers both feedback for the linear process and reciprocal innovation processes such as cocreation, network collaboration, and community innovation. This review and synthesis...

  14. SiO2纳米颗粒与聚氧乙烯对Pickering乳液的协同稳定作用%Stability Mechanisms of Pickering Emulsion Co-stabilized by Silica Nanoparticles and PEO

    Institute of Scientific and Technical Information of China (English)

    谭伟强; 臧渡洋; 李云飞; 张永建; 陆晨君; 栗志广

    2014-01-01

    The Pickering emulsions with 65% water and 35% xylene system stabilized by silica nanoparticles or by both the particles and polyethylene oxide(PEO) additives were prepared. The emulsification was per-formed using a rotor-stator homogenizer under varied rotation speeds from 5000 r/min to 24000 r/min. The emulsion droplets were observed using an optical microscope, consequently, the droplet diameters vs. rotation speed and aging time were obtained. For most cases, W/O type emulsion was obtained. It is found that the mean diameter of water droplets decreases with increasing shear rate or shear duration. With the presence of PEO, the diameters of the droplets are significantly reduced and the phase inversion from W/O to W/O/W is prevented, which occurs in the system without PEO when prolong the shear duration. In addition, the coales-cence of droplets is completely inhibited. To elucidate the ultrastability of the Pickering emulsion resulted from co-stabilization by silica nanoparticles and PEO, we study the rheological properties of the particle layers at the gas-liquid interface using the Langmuir trough equipped with a Wilhelmy plate. The silica nanoparticles were spreaded on the surface of either water or PEO water solution, consequently and the effect of PEO additives on particle layer properties was investigated. The results confirm that PEO additives can favor the trapping of par-ticles at the water/xylene interface, due to the formation of larger size aggregates with the presence of PEO. Therefore, the particle layer has a higher compression modulus. The stronger mechanical property of the parti-cle layer protects the water/xylene interface from rupture when exerted turbulent shearing, hence preventing the occurrence of phase inversion from W/O emulsion to the W/O/W one. Owing to the satisfaction of the Gibbs stability criterion, the coalescence of droplets is almost completely inhibited. The results demonstrate that the rheological properties of the liquid

  15. Solvent vapor induced morphology transition of square slice obtained from PS-b-PEO solution%溶剂诱导嵌段共聚物PS-b-PEO方形片层的形貌转变

    Institute of Scientific and Technical Information of China (English)

    毛虎; 李宏飞; 蒋世春

    2012-01-01

    嵌段共聚物聚苯乙烯-b-聚氧化乙烯(PS-b-PEO)甲苯溶液在室温下陈化2个月可形成中间是PEO单晶上下表面为PS具有“三明治”结构的方形片层,并且既能形成单层方形片层,也能形成多层方形片层.采用透射电子显微镜手段观察了这种结构在不同水含量的水/甲苯混合溶剂蒸汽诱导后形成的结构形貌.结果证明在甲苯和水蒸汽中,方形片层结构均能稳定存在,不能进行结构重构;而随着混合蒸汽中水含量的增加,单晶溶解、消失,在甲苯和水的共同作用下,可通过结构重构形成新的垂直或平行于表面的柱状相结构.%In this paper,the structures of polystyrene-b-poly(ethylene oxide) (PS-b-PEO) square slice formed in toluene solution and transformed in vapor of water/toluene mixtures were investigated via TEM. The square slice can be obtained from PS-b-PEO/toluene solution after ageing for 2 months at room temperature, which is possessed of "sandwich structure" constructed from a PEO single crystal and covered with two tethered PS block layers on the up and down crystal basal surfaces. Not only the single layer square slices, but also the multilayer square slices were both obtained. The PEO single crystal could not be swelled or solvated in toluene vapor and in water vapor,for the poor solubility of toluene for PEO and the barrier of PS layer toward water. Therefore, there were no morphology transitions of the square slice in the two kinds of vapor. With increasing of the water fraction in water/toluene mixtures,the square slices transformed to cylindrical microdomains. The structure rearrangement is due to the dissolution of PEO single crystal and the microphase separation of the block copolymer. The content of water in the mixed solvent is the key factor to the formation of the vapor induced structures. The PEO single crystal could not be solvated in the vapor of mixed solvent with 10% water. So there would no further phase

  16. Optimal Auctions with Financial Externalities

    NARCIS (Netherlands)

    Maasland, E.; Onderstal, A.M.

    2002-01-01

    We construct optimal auctions when bidders face financial externalities.In a Coasean World, in which the seller cannot prevent a perfect resale market, nor withhold the object, the lowest-price all-pay auction is optimal.In a Myersonean World, in which the seller can both prevent resale after the au

  17. Organizing for External Knowledge Sourcing

    DEFF Research Database (Denmark)

    Rabbiosi, Larissa; Reichstein, Toke

    2011-01-01

    The aim of this article is to provide an introduction to the special issue. We briefly consider the external knowledge sourcing and organizing for innovation literatures, which offer a background for the special issue, and we highlight their mutual dialogue. We then illustrate the main findings...

  18. Measuring Externalities in Program Evaluation

    NARCIS (Netherlands)

    Janssens, Wendy

    2005-01-01

    Impact evaluations of development programmes usually focus on a comparison of participants with a control group. However, if the programme generates externalities for non-participants such an approach will capture only part of the programme's impact. Based on a unique large-scale quantitative survey

  19. Lupus vulgaris of external nose.

    Science.gov (United States)

    Bhandary, Satheesh Kumar; Ranganna, B Usha

    2008-12-01

    Lupus vulgaris is the commonest form of cutaneous tuberculosis which commonly involve trunk and buttocks. Lupus vulgaris affecting nose and face, are rarely reported in India. This study reports an unusual case of lupus vulgaris involving the external nose that showed dramatic outcome after six months of anti- tubercular treatment.

  20. [Treatment by external insulin pump].

    Science.gov (United States)

    Clavel, Sylvaine

    2010-12-01

    Since the recent recommendations by the French speaking association for research on diabetes and metabolic illnesses (Alfediam), treatment by insulin pump has found itself in competition with basal-bolus, a procedure using similar injections of insulin which has become a benchmark treatment. The latest Alfediam guidelines focus on defining ways of treating diabetics with an external insulin pump.

  1. Matchings with Externalities and Attitudes

    DEFF Research Database (Denmark)

    Branzei, Simina; Michalak, Tomasz; Rahwan, Talal;

    2013-01-01

    Two-sided matchings are an important theoretical tool used to model markets and social interactions. In many real-life problems the utility of an agent is influenced not only by their own choices, but also by the choices that other agents make. Such an influence is called an externality. Whereas ...

  2. Post-external dacryocystorhinostomy lagophthalmos.

    Science.gov (United States)

    Odat, Thabit A; Odat, Haitham A; Khraisat, Heba; Odat, Mohannad A; Alzoubi, Firas Q

    2015-06-01

    To describe lagophthalmos and eyelid closure abnormality after external dacryocystorhinostomy (DCR). A retrospective review of medical records and postoperative photographs of 79 patients who underwent external DCR for nasolacrimal duct obstruction and developed eyelid closure abnormality and lagophthalmos with or without exposure keratopathy was conducted. Collected data included age, sex, indication for surgery, laterality, length and type of incision, length of follow-up duration, presence of punctate epithelial keratopathy, and time for resolution of eyelid closure abnormalities. Twenty-seven patients with 28 external dacryocystorhinostomy had postoperative eyelid closure abnormalities. Male to female ratio was 1:6. The mean age was 40.1 years (range 9-80 years). All surgeries were performed through diagonal skin incision. Lagophthalmos involving the medial third of the palpebral fissure was noticed in 28.6 % of cases. All patients had hypometric blink mainly of the upper eyelid. One patient had punctate epithelial keratopathy. Resolution of lagophthalmos was noticed over a period of 1-5 weeks with an average of 3 weeks. None of the patients continued to have residual hypometric blink or punctate keratopathy at the last follow-up time. The mean follow-up period was 4.2 months (range 3-6 months). Eyelid closure abnormality and lagophthalmos after external DCR are underestimated problems. Spontaneous resolution is seen in all cases weeks to months after surgery.

  3. Femoral Reconstruction Using External Fixation

    Directory of Open Access Journals (Sweden)

    Yevgeniy Palatnik

    2011-01-01

    Full Text Available Background. The use of an external fixator for the purpose of distraction osteogenesis has been applied to a wide range of orthopedic problems caused by such diverse etiologies as congenital disease, metabolic conditions, infections, traumatic injuries, and congenital short stature. The purpose of this study was to analyze our experience of utilizing this method in patients undergoing a variety of orthopedic procedures of the femur. Methods. We retrospectively reviewed our experience of using external fixation for femoral reconstruction. Three subgroups were defined based on the primary reconstruction goal lengthening, deformity correction, and repair of nonunion/bone defect. Factors such as leg length discrepancy (LLD, limb alignment, and external fixation time and complications were evaluated for the entire group and the 3 subgroups. Results. There was substantial improvement in the overall LLD, femoral length discrepancy, and limb alignment as measured by mechanical axis deviation (MAD and lateral distal femoral angle (LDFA for the entire group as well as the subgroups. Conclusions. The Ilizarov external fixator allows for decreased surgical exposure and preservation of blood supply to bone, avoidance of bone grafting and internal fixation, and simultaneous lengthening and deformity correction, making it a very useful technique for femoral reconstruction.

  4. Defensive externality and blame projection following failure.

    Science.gov (United States)

    Hochreich, D J

    1975-09-01

    This study focuses upon the relationship between internal-external control and defensive blame projection. Trust was used as a moderator variable for making differential predictions concerning the behavior of two subgroups of externals: defensive externals, whose externality is presumed to reflect primarily a verbal technique of defense, and congruent externals, whose externality reflects a more genuine belief that most outcomes are determined by forces beyond their personal control. As predicted, defensive externals showed a stronger tendency than did congruent externals and internals to resort to blame projection following failure at an achievement task. There were no group differences in attribution following task success. Defensive externals were found to be more responsive to negative feedback than were congruent externals.

  5. Electrochemical performance of a solvent-free hybrid ceramic-polymer electrolyte based on Li7La3Zr2O12 in P(EO)15LiTFSI

    Science.gov (United States)

    Keller, Marlou; Appetecchi, Giovanni Battista; Kim, Guk-Tae; Sharova, Varvara; Schneider, Meike; Schuhmacher, Jörg; Roters, Andreas; Passerini, Stefano

    2017-06-01

    The preparation of hybrid ceramic-polymer electrolytes, consisting of 70 wt% of Li+ cation conducting Li7La3Zr2O12 (LLZO) and 30 wt% of P(EO)15LiTFSI polymer electrolyte, through a solvent-free procedure is reported. The LLZO-P(EO)15LiTFSI hybrid electrolytes exhibit remarkable improvement in terms of flexibility and processability with respect to pure LLZO ceramic electrolytes. The physicochemical and electrochemical investigation shows the effect of LLZO annealing, resulting in ion conduction gain. However, slow charge transfer at the ceramic-polymer interface is also observed especially at higher temperatures. Nevertheless, improved compatibility with lithium metal anodes and good Li stripping/plating behavior are exhibited by the LLZO-P(EO)15LiTFSI hybrid electrolytes with respect to P(EO)15LiTFSI.

  6. Dipolar fluids under external perturbations

    Energy Technology Data Exchange (ETDEWEB)

    Klapp, Sabine H L [Stranski-Laboratorium fuer Physikalische und Theoretische Chemie Sekretariat TC7, Technische Universitaet Berlin, Strasse des 17. Juni 124, D-10623 Berlin (Germany)

    2005-04-20

    We discuss recent developments and present new findings on the structural and phase properties of dipolar model fluids influenced by various external perturbations. We concentrate on systems of spherical particles with permanent (point) dipole moments. Starting from what is known about the three-dimensional systems, particular emphasis is given to dipolar fluids in different confining situations involving both simple and complex (disordered) pore geometries. Further topics concern the effect of quenched positional disorder, the influence of external (electric or magnetic) fields, and the fluid-fluid phase behaviour of various dipolar mixtures. It is demonstrated that due to the translational-orientational coupling and due to the long range of dipolar interactions even simple perturbations such as hard walls can have a profound impact on the systems. (topical review)

  7. External observer reflections on QBism

    CERN Document Server

    Khrennikov, Andrei

    2015-01-01

    In this short review I present my personal reflections on QBism. I have no intrinsic sympathy neither to QBism nor to subjective interpretation of probability in general. However, I have been following development of QBism from its very beginning, observing its evolution and success, sometimes with big surprise. Therefore my reflections on QBism can be treated as "external observer" reflections. I hope that my representation of this interpretation of quantum mechanics (QM) has some degree of objectivity. It may be useful for researchers who are interested in quantum foundations, but do not belong to the QBism-community, because I tried to analyze essentials of QBism critically (i.e., not just emphasizing its advantages, as in a typical publication of QBists). QBists may be interested as well - in comments of an external observer who monitored development of this approach to QM during last 16 years. The second part of the paper is devoted to interpretations of probability, objective versus subjective, and view...

  8. Firm Search for External Knowledge

    DEFF Research Database (Denmark)

    Sofka, Wolfgang; Grimpe, Christoph

    2012-01-01

    The innovation performance of modern firms is increasingly determined by their ability to search and absorb external knowledge. However, after a certain threshold firms "oversearch" their environment and innovation performance declines. In this paper, we argue that prior literature has largely...... ignored the institutional context that provides or denies access to external knowledge at the country level. Combining institutional and knowledge search theory, we suggest that the market orientation of the institutional environment and the magnitude of institutional change influence when firms begin...... to experience the negative performance effects of oversearch. Based on a comprehensive sample of almost 8,000 firms from ten European countries, we find that institutions matter considerably for firms' search activity. Higher market orientation of institutions increases the effectiveness of firms' search...

  9. MGR External Events Hazards Analysis

    Energy Technology Data Exchange (ETDEWEB)

    L. Booth

    1999-11-06

    The purpose and objective of this analysis is to apply an external events Hazards Analysis (HA) to the License Application Design Selection Enhanced Design Alternative 11 [(LADS EDA II design (Reference 8.32))]. The output of the HA is called a Hazards List (HL). This analysis supersedes the external hazards portion of Rev. 00 of the PHA (Reference 8.1). The PHA for internal events will also be updated to the LADS EDA II design but under a separate analysis. Like the PHA methodology, the HA methodology provides a systematic method to identify potential hazards during the 100-year Monitored Geologic Repository (MGR) operating period updated to reflect the EDA II design. The resulting events on the HL are candidates that may have potential radiological consequences as determined during Design Basis Events (DBEs) analyses. Therefore, the HL that results from this analysis will undergo further screening and analysis based on the criteria that apply during the performance of DBE analyses.

  10. Network externalities across financial institutions

    OpenAIRE

    Castro Iragorri, Carlos Alberto; Preciado Pua, Sergio Andrés; Ordóñez Herrera, Juan Sebastián

    2016-01-01

    We propose and estimate a financial distress model that explicitly accounts for the interactions or spill-over effects between financial institutions, through the use of a spatial continuity matrix that is build from financial network data of inter bank transactions. Such setup of the financial distress model allows for the empirical validation of the importance of network externalities in determining financial distress, in addition to institution specific and macroeconomic covariates. The re...

  11. Externe Kosten in der Energiewirtschaft

    OpenAIRE

    Voß, Alfred; Friedrich, Rainer

    1994-01-01

    Als externe Effekte werden unbeteiligte Dritte betreffende Zusatzkosten oder Zusatznutzen verstanden, die sich in den jeweiligen Güterpreisen nicht wiederfinden und denen die Betroffenen nicht indifferent gegenüberstehen. Die gegenwärtige Energiebereitstellung und -nutzung ist in vielen Bereichen eine wesentliche Quelle der Belastung von Umwelt und Natur. Begriffe und Schlagworte wie Waldsterben, Tankerunglücke, Tschernobyl und Treibhauseffekt seien in diesem Zusammenhang erwähnt.

  12. Matching Games with Additive Externalities

    DEFF Research Database (Denmark)

    Branzei, Simina; Michalak, Tomasz; Rahwan, Talal

    2012-01-01

    Two-sided matchings are an important theoretical tool used to model markets and social interactions. In many real life problems the utility of an agent is influenced not only by their own choices, but also by the choices that other agents make. Such an influence is called an externality. Whereas......, optimistic, and pessimistic behaviour, and provide both computational hardness results and polynomial-time algorithms for computing stable outcomes....

  13. ENDOSCOPIC DCR VERSUS EXTERNAL DCR

    Directory of Open Access Journals (Sweden)

    Rukma

    2015-04-01

    Full Text Available PURPOSE: To compare success rates of endoscopic dacryocystorhinostomy (DCR and external DCR for acquired nasolacrimal duct obstruction (NLDO. MATERIALS AND METHODS: A prospective comparative non randomized study of 64 patients who presented with acquired NLD obstruction to a tertiary hospital. They were fully evaluated to ascertain the site of obstruction and patients with distal obstruction were included in the study. 34 patients underwent endoscopic DCR and 30 patients underwent external DCR RESULTS: 64 patients were included in the study and 72 procedures carried out. Success was achieved in 65 cases and failure in 7. Of the 7 failed cases, anatomical obstruction at the fistula site was found in 3, whereas functional failure was found in 4. In our patients, endoscopic DCR had a significantly higher success rate than external DCR, 95.23% versus 83.33% (P = 0.03. CONCLUSIONS: The success rate of Endoscopic DCR for acquired NLDO in our group of patients was 95.23%, with endoscopic surgery showing better results.

  14. Conceptual challenges for internalising externalities

    DEFF Research Database (Denmark)

    Miguel, Brandão; Weidema, Bo Pedersen

    2013-01-01

    We analyse a number of different externalities to identify conceptual challenges for the practical implementation of their internalisation. Three issues were identified: i) The balance between compensation and technology change and the respective effects on the nominal and real GDP; ii) The relev......We analyse a number of different externalities to identify conceptual challenges for the practical implementation of their internalisation. Three issues were identified: i) The balance between compensation and technology change and the respective effects on the nominal and real GDP; ii......) The relevance and efficiency of different instruments for internalisation and compensation; and iii) Implementing internalisation over large geographical and temporal distances. We find taxation to be a more relevant and efficient tool for internalisation than insurance and litigation. With increasing...... geographical and especially temporal distance between the benefitting actor and the victim of the external cost, the involvement of a non-governmental intermediate actor becomes increasingly necessary to provide the short-term capital required to ensure a successful implementation....

  15. Individuals' insight into intrapersonal externalities

    Directory of Open Access Journals (Sweden)

    David J. Stillwell

    2012-07-01

    Full Text Available An intrapersonal externality exists when an individual's decisions affect the outcomes of her future decisions. It can result in decreasing or increasing average returns to the rate of consumption, as occurs in addiction or exercise. Experimentation using the Harvard Game, which models intrapersonal externalities, has found differences in decision making between drug users and control subjects, leading to the argument that these externalities influence the course of illicit drug use. Nevertheless, it is unclear how participants who behave optimally conceptualise the problem. We report two experiments using a simplified Harvard Game, which tested the differences in contingency knowledge between participants who chose optimally and participants who did not. Those who demonstrated optimal performance exhibited both a pattern of correct responses and systematic errors to questions about the payoff schedules. The pattern suggested that they learned explicit knowledge of the change in reinforcement on a trail-by-trial basis. They did not have, or need, a full knowledge of the historical interaction leading to each payoff. We also found no evidence of choice differences between participants who were given a guaranteed payment and participants who were paid contingent on their performance, but those given a guaranteed payment were able to report more contingency knowledge as the experiment progressed, suggesting that they explored more rather than settling into a routine. Experiment 2 showed that using a fixed inter-trial interval did not change the results.

  16. Preparation and characterization of PEO based Li1.5Al0.5Ge1.5(PO4)3 solid composite electrolyte%PEO基Li1.5Al0.5Ge1.5(PO4)3固体复合电解质的制备

    Institute of Scientific and Technical Information of China (English)

    余涛; 谢凯; 韩喻; 王珲

    2015-01-01

    以聚环氧乙烷(PEO)为黏结剂,离子导电性的 Li1.5Al0.5Ge1.5(PO4)3(LAGP)为主相,乙腈为溶剂,按照EO/Li,摩尔比为13,变化LiN(CF3SO2)2(LiTFSI)中Li+与LAGP中Li+的比例,通过溶液浇注法制备得到LAGP-PEO(LiTFSI)固体复合电解质。用X射线衍射、扫描电镜(SEM)和电化学阻抗(EIS)等方法对固体复合电解质的形貌、结构和电导率进行表征。结果表明,LAGP 可与 PEO(LiTFSI)部分络合并均匀分散于PEO(LITFSI)内,整个体系内存有三个主体相,即PEO(LiTFSI)的复合相、LAGP晶相以及PEO与两种锂盐的过渡相。通过阻抗谱图发现,当质量比w(LAGP)∶w(PEO)=6∶4时,LAGP-PEO(LiTFSI)固体复合电解质具有最高的室温电导率,为2.68×10−5S/cm,在333 K时,达到1.86×10−4S/cm,接近LAGP的电导率水平。这说明固体复合电解质中加入LAGP即降低了PEO的结晶度,LAGP自身的电导率也有一定贡献。%PEO-based solid composite electrolyte with the fast ion conductor LAGP(Li1.5Al0.5Ge1.5(PO4)3) as a main ionic conductive component and PEO as the binder were prepared by the solution casting method with fixedn(EO)/n(Li)=13, but varying ratio of LiTFSI to LAGP. The structure and morphology of the solid composite electrolyte were characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM). The conductivity of LAGP-PEO(LiTFSI) electrolyte was analyzed by electrical impedance spectroscopy (EIS). The results show that LAGP is partially complexed with PEO(LiTFSI) and homogeneously distributed in PEO(LiTFSI). Three phases are present, a pure crystalline LAGP phase, amorphous PEO(LiTFSI) phase and a transition phase of the LAGP particles and amorphous PEO(LiTFSI). Withw(LAGP)∶w(PEO)=6∶4, the optimal ionic conductivity for LAGP-PEO(LiTFSI) solid composite electrolyte is 2.68×10−5S/cm at room temperature and 1.86×10−4S/cm at 373 K which is close to the LAGP. It means that the LAGP

  17. Sodium-ion-conducting polymer nanocomposite electrolyte of TiO2/PEO/PAN complexed with NaPF6

    Science.gov (United States)

    Bhatt, Chandni; Swaroop, Ram; Sharma, Parul Kumar; Sharma, A. L.

    2016-05-01

    A free standing transparent film of solid state polymer electrolyte based on PEO/PAN+NaPF6 with different compositions of nano sized TiO2 in weight percent (x = 0, 1, 2, 5, 10, 15, 20) is synthesized by using standard solution cast technique. The homogeneous surface of above polymer composition is examined by FESEM. The microscopic interaction among polymer, salt and nanoceramic filler has been analyzed by Fourier Transformed Infra-Red (FTIR) spectroscopy. The reduction of ion pair formation in polymeric separator is clearly observed on addition of nanofiller in the polymer salt complex film. Electrical conductivity has been recorded of the prepared polymeric separator which is of the order of ˜10-4 Scm-1 after addition of nanofiller (15% wt/wt) which support the FTIR results. Electrochemical potential window has been observed of the order of ˜6V by the cyclic voltammetry results. The observed data of the prepared separator are at par with the desirable value for device applications

  18. Improved photovoltage and performance by aminosilane-modified PEO/P(VDF-HFP) composite polymer electrolyte dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jing; Yang, Ying; Wu, Sujuan; Xu, Sheng; Zhou, Conghua; Hu, Hao; Chen, Bolei; Han, Hongwei; Zhao, Xingzhong [Key Laboratory of Acoustic and Photonic Materials and Devices of Ministry of Education, Department of physics, Wuhan University, Wuhan 430072 (China)

    2008-06-30

    A PEO/P(VDF-HFP) composite polymer electrolyte was modified by different amounts of NH{sub 2}-end functional silane (3-amonopropyltriethoxysilane, APTS). Fourier transform infrared (FT-IR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were carried out to examine the configuration changes of the polymer electrolyte. The newly formed Si-O-Si network and interactions influenced the ionic conductivity of the APTS-modified polymer electrolyte and also enhanced the connection of the polymer electrolyte with the electrodes of the dye sensitized solar cells (DSSCs). The cyclic voltammograms and electrochemical impedance measurements indicated that the APTS deprotonated the TiO{sub 2} photoanode surface and negatively changed the Fermi energy level and the conduction band edge to the vacuum level. This effectively reduced the interface recombination in the DSSC and improved the open circuit voltage. With moderate APTS content (0.1 M) modification, the DSSC exhibited a 58 mV improvement of photovoltage and an improved performance of 5.08% compared with 3.74% of the original DSSC. (author)

  19. Improved photovoltage and performance by aminosilane-modified PEO/P(VDF-HFP) composite polymer electrolyte dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Jing; Yang Ying; Wu Sujuan; Xu Sheng; Zhou Conghua; Hu Hao; Chen Bolei; Han Hongwei [Key Laboratory of Acoustic and Photonic Materials and Devices of Ministry of Education, Department of physics, Wuhan University, Wuhan 430072 (China); Zhao Xingzhong [Key Laboratory of Acoustic and Photonic Materials and Devices of Ministry of Education, Department of physics, Wuhan University, Wuhan 430072 (China)], E-mail: xzzhao@whu.edu.cn

    2008-06-30

    A PEO/P(VDF-HFP) composite polymer electrolyte was modified by different amounts of NH{sub 2}-end functional silane (3-amonopropyltriethoxysilane, APTS). Fourier transform infrared (FT-IR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were carried out to examine the configuration changes of the polymer electrolyte. The newly formed Si-O-Si network and interactions influenced the ionic conductivity of the APTS-modified polymer electrolyte and also enhanced the connection of the polymer electrolyte with the electrodes of the dye sensitized solar cells (DSSCs). The cyclic voltammograms and electrochemical impedance measurements indicated that the APTS deprotonated the TiO{sub 2} photoanode surface and negatively changed the Fermi energy level and the conduction band edge to the vacuum level. This effectively reduced the interface recombination in the DSSC and improved the open circuit voltage. With moderate APTS content (0.1 M) modification, the DSSC exhibited a 58 mV improvement of photovoltage and an improved performance of 5.08% compared with 3.74% of the original DSSC.

  20. Some preliminary evaluations of black coating on aluminium AA2219 alloy produced by plasma electrolytic oxidation (PEO) process for space applications

    Science.gov (United States)

    Shrestha, S.; Merstallinger, A.; Sickert, D.; Dunn, B. D.

    2003-09-01

    This paper describes the results of a study of a black coating produced on aluminium AA2219 alloy using a process that involves creation of a hard ceramic oxide layer on the surface of the alloy by plasma electrolytic oxidation (PEO) known as the 'KERONITE®' process. Coating microstructure has been examined and the coating characteristics such as porosity, hardness, adhesion and phase composition were measured. The thermo-optical properties such as solar absorptance 'as' and normal infrared emittance 'en-IR' of the coating were measured in the 'as-prepared' condition and after environmental exposures to humidity, thermal cycling and UV-radiation in vacuum and to thermal shock. Comparison was made with alternative coatings produced using standard black anodising processes. The study also looked at the cold welding and friction behaviours of the coated alloy in vacuum and in an ambient laboratory environment. Standard spacecraft materials tests were conducted on the coated disc against an AISI 52100 steel ball and also against a coated pin using a pin-on-disc apparatus. Parameters such as friction coefficient and wear depth were measured and the cold welding behaviours were investigated. Test results were compared with the data generated for NiCr plated and anodised coatings. Corrosion performance was assessed using a salt spray exposure test and using an accelerated electrochemical test method. In addition, the study looked at the effect of post coating sealing with a sol-gel solution.

  1. Antibacterial Properties of Tough and Strong Electrospun PMMA/PEO Fiber Mats Filled with Lanasol—A Naturally Occurring Brominated Substance

    Directory of Open Access Journals (Sweden)

    Richard L. Andersson

    2014-09-01

    Full Text Available A new type of antimicrobial, biocompatible and toughness enhanced ultra-thin fiber mats for biomedical applications is presented. The tough and porous fiber mats were obtained by electrospinning solution-blended poly (methyl methacrylate (PMMA and polyethylene oxide (PEO, filled with up to 25 wt % of Lanasol—a naturally occurring brominated cyclic compound that can be extracted from red sea algae. Antibacterial effectiveness was tested following the industrial Standard JIS L 1902 and under agitated medium (ASTM E2149. Even at the lowest concentrations of Lanasol, 4 wt %, a significant bactericidal effect was seen with a 4-log (99.99% reduction in bacterial viability against S. aureus, which is one of the leading causes of hospital-acquired (nosocomial infections in the world. The mechanical fiber toughness was insignificantly altered up to the maximum Lanasol concentration tested, and was for all fiber mats orders of magnitudes higher than electrospun fibers based on solely PMMA. This antimicrobial fiber system, relying on a dissolved antimicrobial agent (demonstrated by X-ray diffraction and Infrared (IR-spectroscopy rather than a dispersed and “mixed-in” solid antibacterial particle phase, presents a new concept which opens the door to tougher, stronger and more ductile antimicrobial fibers.

  2. Preparation of MWNTs/PVA/PEO composite fiber by electrospinning process%静电纺丝制备MWNTs/PVA/PEO复合超细纤维

    Institute of Scientific and Technical Information of China (English)

    马彦龙; 王帅; 卫英慧; 郭有军; 张凯丽

    2010-01-01

    采用硝酸对多壁碳纳米管(MwNTs)进行纯化处理,利用表面活性剂十二烷基磺酸钠(SDS)或聚乙烯醇(PVA)对纯化后的MWNTs进行了表面修饰,将修饰后的MWNTs添加到PVA和聚氧化乙烯(PEO)共混水溶液中,通过静电纺丝制备了 MWNTs/PVA/PEO复合超细纤维.结果表明:PVA修饰的MWNTs比SDS修饰的MWNTs在PVA/PEO纺丝液中有更好的分散稳定性.随MWNTs添加量的增加,纤维的平均直径减小;当添加PVA修饰的MWNTs质量分数为0.53%时,纤维平均直径达368 nm,且纤维表面光滑、分布均匀.

  3. LLTO纳米粒子改性的PVDF-PEO基复合微孔聚合物膜%Composite PVDF-PEO based microporous polymer membrane reinforced by LLTO nanoparticle

    Institute of Scientific and Technical Information of China (English)

    雷英; 郭勇; 林琳; 欧俊科; 张永志; 肖丹

    2011-01-01

    Composite microporous polymer membrane based on poly ( vinylidene fluoride ) ( PVDF ) , poly ( ethylene oxide ) ( PEO ) , and La0.5 Li0.5 TiO3 ( LLTO) nanoparticle ( denoted as PVDF - PEO/LLTO) was prepared by a simple phase inversion technique. LLTO nanoparticle can improve the electrochemical properties with forming new channels on its surface. When the content of LLTO is 8% ,the porosity of the composite microporous membranes is up to 62. 38% ,liquid electrolyte( 1 mol L-1 LiPF6/EC/DMC solution)weight uptake is 240. 28% ,ionic conductivity is up to 2. 15 x 10~3 S/cm,and the electrochemical window is 4. 5V. The high room temperature ionic conductivity combined with good electrochemical stability implies that PVDF - PEO/LLTO based composite microporous polymer membrane can be used as candidate separator material for practical applications in lithium ion batteries.%采用简单的相转化法制备了掺杂La0.5Li0.5TiO3(LLTO)的以聚偏氟乙烯(PVDF)和聚氧乙烯(PEO)为基体的PVDF-PEO/LLTO复合微孔聚合物膜.添加入LLTO快离子导体后,由于在LLTO的表面形成了新的锂离子传输通道,使得复合微孔聚合物膜的电化学性能提高.当LLTO的掺杂量为8%时,该复合微孔膜的孔隙率和吸液性能分别可达到62.38%和240.28%,吸液后室温锂离子电导率可达2.15×10-3Scm-1,电化学稳定窗口可达4.5V.可见,这种具有较高的锂离子电导率和电化学稳定性较好的复合微孔膜可为锂离子电池的隔膜材料提供新的选择.

  4. Skepticism, Contextualism, Externalism and Modality

    Directory of Open Access Journals (Sweden)

    Ron Wilburn

    2006-12-01

    Full Text Available In this paper, I argue for the following claims. Contextualist strategies to tame or localize epistemic skepticism are hopeless if contextualist factors are construed internalistically. However, because efforts to contextualize externalism via subjunctive conditional analysis court circularity, it is only on an internalistic interpretation that contextualist strategies can even be motivated. While these claims do not give us an argument for skepticism, they do give us an argument that contextualism, as such, is not likely to provide us with an argument against skepticism.

  5. Leveraging External Sources of Innovation

    DEFF Research Database (Denmark)

    West, Joel; Bogers, Marcel

    2014-01-01

    own specific set of mechanisms and conditions. Integrating innovations has been mostly studied from an absorptive capacity perspective, with less attention given to the impact of competencies and culture (including “not invented here”). Commercializing innovations puts the most emphasis on how......” in a way inconsistent with earlier definitions in innovation management. The paper concludes with recommendations for future research that include examining the end-to-end innovation commercialization process, and studying the moderators and limits of leveraging external sources of innovation....

  6. 静电纺PVA/PEO共混纳米纤维膜的制备与性能表征%Preparation and characterization of PVA/PEO blended nanofiber films prepared by electrospinning

    Institute of Scientific and Technical Information of China (English)

    王春红; 刘胜凯; 贺文婷; 王莹

    2015-01-01

    The poly vinyl alcohol (PVA)-poly ethylene oxide (PEO) blend nanofiber films was produced with electrospin-ning technology. The mechanical properties of blend films were tested, fiber microstructure was investigated by SEM, and thermal properties of films were investigated with TGA and DSC. The effects of mass ratio of PVA to PEO on the properties of blend films were analyzed. The results indicate that too much or too little PEO have no obvious improvement on the ability of forming wires of blend films, and when the mass ratio of PVA to PEO is 5∶5, the blend film has good ability of forming wires, the fiber is fine and uniform. Compared with pure films, the mechanical properties of blend films are improved in different degrees, when the mass ratio of PVA to PEO is 7∶3, the elongation and strength of blend films increase by 1 545.71%!and 66%, respectively. The thermal stability of PVA/PEO blend films are better than those of pure films, but the amount of PEO has little effect on the thermal properties of blend films.%采用静电纺丝技术制备聚乙烯醇(PVA)/聚氧化乙烯(PEO)共混纳米纤维膜,测试共混纤维膜的拉伸力学性能,采用SEM观察其微观形貌和结构,利用TGA和DSC分析共混纤维膜的热学性能,考察PEO与PVA共混比例对纤维膜性能的影响.结果表明:PEO加入过多或过少对共混纤维膜结构均无明显改善,当PVA∶PEO质量比为5∶5时,所得纤维膜成丝性和成膜性最佳,膜中纤维线密度最小且粗细均匀;与纯纺纤维膜相比,不同共混比例PVA/PEO纤维膜的力学性能均有不同程度提升,当PVA与PEO质量比为7∶3时其断裂强度和断裂伸长率较纯PVA分别提高了66%和1545.71%;PVA/PEO共混纤维膜的热稳定性优于纯PVA纤维膜,但PEO加入量的变化对共混纤维膜热学性能的影响较小.

  7. Empirical Evaluation On External Debt Of Malaysia

    OpenAIRE

    Nor’Aznin Abu Bakar; Sallahuddin Hassan

    2011-01-01

    This study analyzes the effects of external debts on economic growth in Malaysia. The analysis is conducted both at aggregate and disaggregate levels. The empirical results are based on VAR estimates using GDP, external debts, capital accumulation, labor force and human capital. Estimation results at the aggregate level indicate that total external debts affect economic growth positively. In particular, one percentage point increase in total external debts generates 1.29 percentage point of e...

  8. 含烷氧磺酸锂盐及对称星形醚的聚环氧乙烷基聚合物电解质的制备及电化学性能%Preparation and Electrochemical Performance of PEO Based Polymer Electrolyte Containing Pentaerythritol Tetrakis(2-methoxyethyl ether)and Lithium Methoxy Oligo(oxyethylene)sulfate

    Institute of Scientific and Technical Information of China (English)

    古宁宇; 余佃宝; 谢媛媛; 杨震宇; 张荣斌; 刘峰

    2011-01-01

    lithium methoxy oligo ( oxyethylene ) sulfate ( LiSA ( EO) n) and pentaerythritol tetrakis ( 2-methoxyethyl ether) (STEO) were synthesized and used for the preparation of polyethylene oxide (PEO) based polymer electrolytes. All solid-state polymer electrolytes PEO-LiSA (EO)n and PEO-LiClO4 were obtained by the solvent casting method and the ionic conductivities and lithium ion transference numbers were measured by using ac impedance and steady state current methods respectively. The influences of lithium salt structure on lithium ion transference numbers and ionic conductivities of polymer electrolytes were studied. Results showed that, comparing with LiClO4 , LiSA ( EO) n could enhance the ionic conductivity of polymer electrolytes and ionic conductivity decreased with increasing size of anion of lithium salt. Lithium ion transference numbers increased with increasing size of anion of lithium salt, and achieved a relatively high value of 0. 35 when (PEO16 + LiSA(EO)2) was used. Composed polymer electrolytes ( CPEs) PEO16-LiSAEO-STEO were prepared and the effects of addition of STEO on ionic conductivities were discussed. The experimental results showed that the addition of STEO could improve the ionic conductivity of the composited polymer electrolytes effectively, the ionic conductivity of PEO 16-LiSAEO-20%STEO achieved 0. 5 x 10-4 S/cm under 25℃. The thermal properties of CPEs were investigated by DSC experiments. Results indicated that the addition of STEO could decrease the melting temperature and crystallinity of CPE, resulting in the improvement of ionic conductivity. The electrochemical stability window of PEO16-liSAEO-20% STEO exceeded 4.4 V, which ensured the use of PEO16-LiSAEO-STEO as electrolyte materials for all solid-state rechargeable lithium ion batteries.%合成了低聚度烷氧磺酸锂盐(LiSA(EO)n)和对称星形醚(STEO)增塑剂,并制备了聚环氧乙烷(PEO)基聚合物电解质.研究了 PEO16+LiSA(EO)n体系的锂离子迁移数

  9. Clinical Manifestations, Pathological Changes and Diagnosis of Chronic Progressive External Ophthalmoplegia(Six Cases Attached)%慢性进行性眼外肌麻痹的临床、病理及诊断(附6例报道)

    Institute of Scientific and Technical Information of China (English)

    卢家红; 林洁; 黄俊; 赵重波; 汪寅

    2006-01-01

    目的:探讨慢性进行性眼外肌麻痹(CPEO)的临床、病理及诊断.方法:对6例CPEO患者的临床表现、病理特点进行分析并与另5组CPEO比较.结果:6例患者中男3例,女3例,平均起病年龄13岁.2例为同胞兄弟.6例均有进行性加重的双睑下垂和眼球活动障碍,其中1例起病不对称.除眼外肌麻痹外,3例闭目肌力减退、1例轻度吞咽困难、1例轻度肢体无力.3例伴内分泌功能异常.肌活检破碎红纤维(RRF)阳性肌纤维数和细胞色素氧化酶(cytochrome oxidase,COX)阴性肌纤维数均明显>2%.结论:CPEO的主要临床表现为进行性发展的眼外肌麻痹,可伴肢体肌无力、视网膜色素变性、听力障碍、心脏传导异常、内分泌异常等.诊断主要依赖临床和肌肉活检中发现>2%的RRF+肌纤维、COX-肌纤维.

  10. Quantum Electrodynamics on background external fields

    CERN Document Server

    Marecki, P

    2003-01-01

    The quantum electrodynamics in presence of background external fields is developed. Modern methods of local quantum physics allow to formulate the theory on arbitrarily strong possibly time-dependent external fields. Non-linear observables which depend only locally on the external field are constructed. The tools necessary for this formulation, the parametrices of the Dirac operator, are investigated.

  11. 46 CFR 154.452 - External pressure.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false External pressure. 154.452 Section 154.452 Shipping... Independent Tank Type C and Process Pressure Vessels § 154.452 External pressure. The design external pressure...) for tanks without a vacuum relief valve. P2=0, or the pressure relief valve setting for an enclosed...

  12. 46 CFR 64.19 - External pressure.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false External pressure. 64.19 Section 64.19 Shipping COAST... HANDLING SYSTEMS Standards for an MPT § 64.19 External pressure. (a) A tank without a vacuum breaker must be designed to withstand an external pressure of 71/2 psig or more. (b) A tank with a vacuum breaker...

  13. 49 CFR 195.108 - External pressure.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false External pressure. 195.108 Section 195.108 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... PIPELINE Design Requirements § 195.108 External pressure. Any external pressure that will be exerted on the...

  14. Quantum electrodynamics on background external fields

    OpenAIRE

    2003-01-01

    The quantum electrodynamics in presence of background external fields is developed. Modern methods of local quantum physics allow to formulate the theory on arbitrarily strong possibly time-dependent external fields. Non-linear observables which depend only locally on the external field are constructed. The tools necessary for this formulation, the parametrices of the Dirac operator, are investigated.

  15. Externally Wetted Ionic Liquid Thruster

    Science.gov (United States)

    Lozano, P.; Martinez-Sanchez, M.; Lopez-Urdiales, J. M.

    2004-10-01

    This paper presents initial developments of an electric propulsion system based on ionic liquid ion sources (ILIS). Propellants are ionic liquids, which are organic salts with two important characteristics; they remain in the liquid state at room temperature and have negligible vapor pressure, thus allowing their use in vacuum. The working principles of ILIS are similar to those of liquid metal ion sources (LMIS), in which a Taylor cone is electrostatically formed at the tip of an externally wetted needle while ions are emitted directly from its apex. ILIS have the advantage of being able to produce negative ions that have similar masses than their positive counterparts with similar current levels. This opens up the possibility of achieving plume electrical neutrality without electron emitters. The possible multiplexing of these emitters is discussed in terms of achievable thrust density for applications other than micro-propulsion.

  16. External symmetry in general relativity

    CERN Document Server

    Cotaescu, I I

    2000-01-01

    We propose a generalization of the isometry transformations to the geometric context of the field theories with spin where the local frames are explicitly involved. We define the external symmetry transformations as isometries combined with suitable tetrad gauge transformations and we show that these form a group which is locally isomorphic with the isometry one. We point out that the symmetry transformations that leave invariant the equations of the fields with spin have generators with specific spin terms which represent new physical observables. The examples we present are the generators of the central symmetry and those of the maximal symmetries of the de Sitter and anti-de Sitter spacetimes derived in different tetrad gauge fixings. Pacs: 04.20.Cv, 04.62.+v, 11.30.-j

  17. ANALYSIS OF EXTERNAL FACTORS AFFECTING THE PRICING

    Directory of Open Access Journals (Sweden)

    Irina A. Kiseleva

    2013-01-01

    Full Text Available The external factors influencing the process of formation of tariffs of commercial services are considered in the article. External environment is known to be very diverse and changeable. Currently, pricing has become one of the key processes of strategic development of a company. Pricing in the service sector, in turn, is highly susceptible to changes in the external environment. Its components directly or indirectly affect the market of services, changing it adopted economic processes. As a rule, firms providing services can’t influence the changes in external factors. However, the service market is very flexible, which enables businesses to reshape pricing strategy, to adapt it to the new environment.

  18. Control of External Kink Instability

    Science.gov (United States)

    Navratil, Gerald

    2004-11-01

    A fundamental pressure and current limiting phenomenon in magnetically confined plasmas for fusion energy is the long wavelength ideal-MHD kink mode. These modes have been extensively studied in tokamak and reversed field pinch (RFP) devices. They are characterized by significant amplitude on the boundary of the confined plasma and can therefore be controlled by manipulation of the external boundary conditions. In the past ten years, the theoretically predicted stabilizing effect of a nearby conducting wall has been documented in experiments, which opens the possibility of a significant increase in maximum stable plasma pressure. While these modes are predicted to remain unstable when the stabilizing wall is resistive, their growth rates are greatly reduced from the hydrodynamic time scale to the time scale of magnetic diffusion through the resistive wall. These resistive wall slowed kink modes have been identified as limiting phenomena in tokamak (DIII-D, PBX-M, HBT-EP, JT-60U, JET, NSTX) and RFP (HBTX, Extrap, T2R) devices. The theoretical prediction of stabilization to nearly the ideal wall pressure limit by toroidal plasma rotation and/or active feedback control using coils has recently been realized experimentally. Sustained, stable operation at double the no-wall pressure limit has been achieved. Discovery of the phenomenon of resonant field amplification by marginally stable kink modes and its role in the momentum balance of rotationally stabilized plasmas has emerged as a key feature. A theoretical framework, based on an extension of the very successful treatment of the n=0 axisymmetric mode developed in the early 1990's, to understand the stabilization mechanisms and model the performance of active feedback control systems is now established. This allows design of kink control systems for burning plasma experiments like ITER.

  19. Dynamic Evolution in PVPh/PEO Blend Studied by Solid-State NMR%PVPh/PEO共混物动力学演化过程的NMR研究

    Institute of Scientific and Technical Information of China (English)

    彭永进; 孙平川; 李宝会

    2016-01-01

    聚合物共混物中链段的慢取向运动与其玻璃化转变行为和宏观力学性质密切关联,而基于化学位移各向异性重聚的13C CODEX(centerband-only detection of exchange)固体核磁共振(SSNMR)技术能够有效表征共混物中链段的慢取向运动。该文利用13C CODEX NMR技术详细研究了相容性聚合物共混物聚乙烯基苯酚/聚氧乙烯(PVPh/PEO)中的刚性组分 PVPh 在较宽温度范围内的慢取向运动特性与玻璃化转变过程的关联。研究表明,在玻璃化转变起始温度以下,PVPh主链的分子运动被冻结,而侧基存在b-松弛的慢取向运动;在玻璃化转变起始温度附近,PVPh主链具有明显的慢取向运动,而且主链和侧基是一种协同的分子运动。该文利用 NMR 技术揭示了共混物中的玻璃化转变起止温度分别对应于高分子主链慢取向运动CODEX信号的开始和极大值处的温度。%The13C centerband-only-detection-of-exchange (CODEX) variable-temperature solid-state NMR (SSNMR) technique was used to investigate the evolution of segmental dynamics in poly (vinyl phenol) (PVPh)/ poly (ethylene oxide) (PEO) polymer blend within a wide range of temperatures. It was found that the glass transition began with the emergence of remarkable slow motions of the PVPh backbone segments, and ended when the CODEX signal intensity of segmental slow motion reached maximum. The SSNMR results revealed, at molecular level, that the onset and endpoint of conventional calorimetric glass transition are closely associated with the evolution of slow motions in this polymer blend.

  20. Externalities and Compensation : Primeval Games and Solutions

    NARCIS (Netherlands)

    Ju, Y.; Borm, P.E.M.

    2005-01-01

    The classical literature (Pigou (1920), Coase (1960), Arrow (1970)) and the relatively recent studies (cf.Varian (1994)) associate the externality problem with efficiency.This paper focuses explicitly on the compensation problem in the context of externalities.To capture the features of inter-indivi

  1. Concurrent sourcing and external supplier opportunism

    DEFF Research Database (Denmark)

    Mols, Niels Peter

    When a firm simultaneously makes and buys the same components then the firm uses concurrent sourcing. This paper presents an agency model for explaining how and when concurrent sourcing reduces the likelihood of external supplier opportunism. In the proposed model, the external supplier’s expected...

  2. Crossing boundaries : Involving external parties in innovation

    NARCIS (Netherlands)

    Slot, J.H.

    2013-01-01

    To improve the return on investments in innovation, firms increasingly open up their new product development (NPD) processes by inviting external parties to participate. This dissertation focuses on the involvement of three different types of external parties in the NPD process: suppliers, customers

  3. Computing betweenness centrality in external memory

    DEFF Research Database (Denmark)

    Arge, Lars; Goodrich, Michael T.; Walderveen, Freek van

    2013-01-01

    Betweenness centrality is one of the most well-known measures of the importance of nodes in a social-network graph. In this paper we describe the first known external-memory and cache-oblivious algorithms for computing betweenness centrality. We present four different external-memory algorithms...

  4. Lattice Planar QED in external magnetic field

    CERN Document Server

    Cea, Paolo; Giudice, Pietro; Papa, Alessandro

    2011-01-01

    We investigate planar Quantum ElectroDynamics (QED) with two degenerate staggered fermions in an external magnetic field on the lattice. Our preliminary results indicate that in external magnetic fields there is dynamical generation of mass for two-dimensional massless Dirac fermions in the weak coupling region. We comment on possible implications to the quantum Hall effect in graphene.

  5. Internal and External Forces in Language Change.

    Science.gov (United States)

    Yang, Charles D.

    2000-01-01

    Develops a model of language change characterizing the dynamic interaction between internal universal grammar and external linguistic evidence, as mediated by language acquisition. Borrows insights from the study of biological evolution, where internal and external forces interact in similar fashion. Applies the model to explore the loss of the…

  6. Forms of Spanking and Children's Externalizing Behaviors

    Science.gov (United States)

    Lansford, Jennifer E.; Wager, Laura B.; Bates, John E.; Pettit, Gregory S.; Dodge, Kenneth A.

    2012-01-01

    Research suggests that corporal punishment is related to higher levels of child externalizing behavior, but there has been controversy regarding whether infrequent, mild spanking predicts child externalizing or whether more severe and frequent forms of corporal punishment account for the link. Mothers rated the frequency with which they spanked…

  7. Environmental externalities related to power production on biogas and natural gas based on the EU ExternE methodology

    DEFF Research Database (Denmark)

    Nielsen, Per Sieverts; Ibsen, Liselotte Schleisner

    1998-01-01

    This paper assesses the environmental impacts and external costs from selected electricity generation systems in Denmark. The assessment is carried out as part of the ExternE National Implementation, which is the second phase of the ExternE project and involves case studies from all Western Europ...... show that estimated damages due to the greenhouse effect are predominant, however, the uncertainty is high. The predominant damage at the local and regional level is related to emission of NOx, which results in effects on public health....... European countries. The project use a “bottom-up” methodology to evaluate the external costs associated with a wide range of different fuel cycles. The project has identified priority impacts, where most are impacts from air emissions. Externalities due to atmospheric emissions are calculated through...... the use of a software package, EcoSence, having an environmental database at both a local and regional level including population, crops, building materials and forest. The system also incorporates two air transport models, allowing local and regional scale modelling. The results of the Danish case study...

  8. Use of Automated External Defibrillators

    Energy Technology Data Exchange (ETDEWEB)

    Gregory K Christensen

    2009-02-01

    In an effort to improve survival from cardiac arrest, the American Heart Association (AHA) has promoted the Chain of Survival concept, describing a sequence of prehospital steps that result in improved survival after sudden cardiac arrest. These interventions include immediate deployment of emergency medical services, prompt cardiopulmonary resuscitation, early defibrillation when indicated, and early initiation of advanced medical care. Early defibrillation has emerged as the most important intervention with survival decreasing by 10% with each minute of delay in defibrillation. Ventricular Fibrillation (VF) is a condition in which there is uncoordinated contraction of the heart cardiac muscle of the ventricles in the heart, making them tremble rather than contract properly. VF is a medical emergency and if the arrhythmia continues for more than a few seconds, blood circulation will cease, and death can occur in a matter of minutes. During VF, contractions of the heart are not synchronized, blood flow ceases, organs begin to fail from oxygen deprivation and within 10 minutes, death will occur. When VF occurs, the victim must be defibrillated in order to establish the heart’s normal rhythm. On average, the wait for an ambulance in populated areas of the United States is about 11 minutes. In view of these facts, the EFCOG Electrical Safety Task Group initiated this review to evaluate the potential value of deployment and use of automated external defibrillators (AEDs) for treatment of SCA victims. This evaluation indicates the long term survival benefit to victims of SCA is high if treated with CPR plus defibrillation within the first 3-5 minutes after collapse. According to the American Heart Association (AHA), survival rates as high as 74% are possible if treatment and defibrillation is performed in the first 3 minutes. In contrast survival rates are only 5% where no AED programs have been established to provide prompt CPR and defibrillation. ["CPR statistics

  9. Phenotype and clinical course in a family with a new de novo Twinkle gene mutation

    DEFF Research Database (Denmark)

    Jeppesen, Tina Dysgaard; Schwartz, M.; Colding-Jorgensen, E.;

    2008-01-01

    The Twinkle gene product is important for mtDNA replication. Only a few reports have investigated the clinically effect of mutations in this gene. We describe a new de novo mutation (1110C > A) in the PEO1 gene in a mother and her two sons. The mother had progressive ophthalmoplegia, limb weakness...

  10. Concurrent sourcing and external supplier opportunism

    DEFF Research Database (Denmark)

    Mols, Niels Peter

    When a firm simultaneously makes and buys the same components then the firm uses concurrent sourcing. This paper presents an agency model for explaining how and when concurrent sourcing reduces the likelihood of external supplier opportunism. In the proposed model, the external supplier’s expected...... costs of opportunism are determined as a product of four factors. The four factors are: likelihood of discovering supplier opportunism, buyer’s internalized quantity as reaction to supplier opportunism, asset specificity of external supplier’s investments, and multiplicator effects. Each...

  11. Environment and externalization; Environnement et externalisation

    Energy Technology Data Exchange (ETDEWEB)

    Kremlis, G.; Renaud, R. [Association francaise des ingenieurs et techniciens de l' environnement, AFITE, 75 - Paris (France); Touron, M. [Veritas, 75 - Paris (France)] [and others

    2001-07-01

    This document presents the discussions of the 16 may 2000, concerning the externalization and the environment and proposes to answer the following questions: is the externalization a new strategy to better perceive, hopeful engineering department, the technological risks problems, the environment or the land pollution? Does the externalization allow a better organization of the enterprise? To analyse the situation, the document presents the white book of the environmental liability, the administration point of view, some enterprises examples and the importance of the environmental management. (A.L.B.)

  12. Leiomyosarcoma of the external iliac vein.

    Science.gov (United States)

    Fukuda, Wakako; Taniguchi, Satoshi; Fukuda, Ikuo

    2012-06-01

    Leiomyosarcoma of the iliac vein is an uncommon tumor. We report a case of a 63-year-old Japanese woman with leiomyosarcoma of the right external iliac vein. The patient complained of right inguinal pain and swelling. Computed tomography demonstrated a mass surrounding the right external iliac artery and vein. Metastases in the lungs and liver were found. Complete resection of the tumor along with the involved vessels was performed. Polytetrafluoroethylene grafts were used to reconstruct the vessels. Pathological examination revealed leiomyosarcoma of the external iliac vein. Although the prognosis of leiomyosarcoma is poor, en bloc tumor resection is the treatment of choice.

  13. The sustainability of Serbia's external position: The impact of fiscal adjustment and external shocks

    Directory of Open Access Journals (Sweden)

    Zildžović Emir

    2015-01-01

    Full Text Available This paper studies the impact of fiscal policy and external shocks on the sustainability of Serbia’s external position. The key determinants of Serbia's current account balance are identified using model averaging techniques and are compared with estimates obtained for other small open economies (Poland, Georgia, Morocco, Ukraine, and Estonia. The paper uses estimated influences of macrovariables on the current account balance to generate a rich set of possible outcomes for the external position of the country. The results suggest the importance of fiscal policy for the reduction of external imbalances in all countries in our sample. In particular, credible and sustained fiscal adjustment can reduce current account deficit and stabilize Serbia’s external position close to its current level over the medium term. The analysis also warns that lack of success in fiscal consolidation coupled with external shocks may easily push the external position onto an unsustainable path.

  14. Externality, environment, and obesity in children.

    Science.gov (United States)

    Stager, S F

    1981-07-01

    On the assumption that external responsiveness and environmental characteristics jointly determine whether a child will achieve an excessive weight gain, perpetuating and maintaining obesity, probability hierarchy was hypothesized and tested. Ss of the study were 24 obese and 24 average-weight, white boys, mean age 9 years, 5 months. An auditory distraction task and Kagan's Matching Familiar Figures Test were used to measure auditory and visual responsivity to external cues, respectively. Socioeconomic status was used as an indicator of the childhood environment. As predicted, the greatest percentages of obese children were observed in the lower-socioeconomic, external group, followed by the lower-socioeconomic, internal group and middle-socioeconomic, external group. The smallest percentage of obese children was observed in the middle-socioeconomic, internal group.

  15. Proceedings: National conference on environmental externalities

    Energy Technology Data Exchange (ETDEWEB)

    1990-12-31

    This report is the proceedings of the National Conference on Environmental Externalities. A environmental externality is the environmental impact of a process or a plant that society must endure. It is a social cost and is paid, but not by the company who produced it or the company`s customers who endure it. The main purpose of this report is to gather the many designs and ideas of how and why to internalize the externalities into the pricing systems of the public utility commissions, especially that of the electric utilities. Economic and sociological aspects of the internalization of these externalities are given in these proceedings. Individual papers are processed separately for databases. (MB)

  16. Owl Mountain Partnership : An external assessment

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — External review of the Owl Mountain Partnership (OMP) to identify benefits and successes associatedwith collaborative work through the perceptions of participating...

  17. Infrared limit in external field scattering

    CERN Document Server

    Herdegen, Andrzej

    2012-01-01

    Scattering of electrons/positrons by external classical electromagnetic wave packet is considered in infrared limit. In this limit the scattering operator exists and produces physical effects, although the scattering cross-section is trivial.

  18. reoperation rates following intramedullary nailing versus external ...

    African Journals Online (AJOL)

    Reasons for reoperation among EF patients were infection. (2 patients) ... fixation. Keywords: Orthopaedic surgery, Tanzania, Intramedullary nail, External fixation, Open tibia fracture. INTRODUCTION ..... of surgical site infection. Infect Control ...

  19. Consumption Externalities, Rental Markets and Purchase Clubs.

    OpenAIRE

    Suzanne Scotchmer

    2002-01-01

    A premise of general equilibrium theory is that private goods are rival. Nevertheless, many private goods are shared, e.g., through barter, through co-ownership, or simply because one person’s consumption affects another person’s wellbeing. We analyze consumption externalities from the perspective of club theory, and argue that, provided consumption externalities are limited in scope, they can be internalized through membership fees to groups. Our main applications are to rental markets and “...

  20. Operating protocols of external root cervical resorption

    OpenAIRE

    Luca Venuti

    2015-01-01

    Aim: Theme of this report is the external cervical root resorption and the sequence of clinical procedures to be implemented during the phases of treatment. The external cervical root resorption (ICR) presents particular pathological conditions such as to classify between resorption of inflammatory origin.1–3 It is generally presented as a complex clinical situation both in the diagnosis in a predictable prognosis.3–6 It's often associated with loss of calcified tissue: dentin, cementum, a...

  1. Inferential knowledge, externalism and self-knowledge.

    OpenAIRE

    R G Ford

    2004-01-01

    Privileged self-knowledge says, roughly, that we have non-empirical knowledge of our own thoughts. Externalism about mental content says, roughly, that our mental states are determined at least in part by our environment. It has been alleged that jointly assuming externalism about mental content and privileged self-knowledge are true has the consequence that any subject can have non-empirical knowledge of her own environment and this is intuitively absurd. The thesis investigates in various w...

  2. Operating protocols of external root cervical resorption

    OpenAIRE

    Venuti, Luca

    2015-01-01

    Aim: Theme of this report is the external cervical root resorption and the sequence of clinical procedures to be implemented during the phases of treatment. The external cervical root resorption (ICR) presents particular pathological conditions such as to classify between resorption of inflammatory origin.1–3 It is generally presented as a complex clinical situation both in the diagnosis in a predictable prognosis.3–6 It's often associated with loss of calcified tissue: dentin, cementum, a...

  3. Integrating Building Functions into Massive External Walls

    Directory of Open Access Journals (Sweden)

    Ahmed Hisham Hafez

    2016-05-01

    Full Text Available Well into the twentieth century, brick and stone were the materials used. Bricklaying and stonemasonry were the construction technologies employed for the exterior walls of virtually all major structures. However, with the rise in quality of life, the massive walls alone became incapable of fulfilling all the developed needs. Adjacent systems and layers had then to be attached to the massive layer. Nowadays, the external wall is usually composed of a layered construction. Each external wall function is usually represented by a separate layer or system. The massive layer of the wall is usually responsible for the load-bearing function.Traditional massive external walls vary in terms of their external appearance, their composition and attached layers. However, their design and construction process is usually a repeated process. It is a linear process where each discipline is concerned with a separate layer or system. These disciplines usually take their tasks away and bring them back to be re-integrated in a layered manner. New massive technologies with additional function have recently become available.Such technologies can provide the external wall with other functions in addition to its load-bearing function. The purpose of this research is to map the changes required to the traditional design and construction process when massive technologies with additional function are applied in external walls. Moreover, the research aims at assessing the performance of massive solutions with additional function when compared to traditional solutions in two different contexts, the Netherlands and Egypt.Through the analysis of different additional function technologies in external walls, a guidance scheme for different stakeholders is generated. It shows the expected process changes as related to the product level and customization level. Moreover, the research concludes that the performance of additional insulating technologies, and specifically Autoclaved

  4. External Prestressing Bridge Reinforcement Technology Review

    Directory of Open Access Journals (Sweden)

    Zhu Hanbing

    2015-01-01

    Full Text Available Externally prestressed bridge can not only limit and reduce the cracks and deformation of the structure, improve the rigidity and bearing capacity of structure, improve the stress state of structure, but also have less interference for bridge operation when it is operating and have the good economic efficiency. This paper introduces the advantages and disadvantages of external prestressed strengthening technique, its calculation theory and construction technology described in detail, and finally the paper discusses the deficiency of existing research.

  5. Nuclear waste storage and environmental intergenerational externalities

    OpenAIRE

    Fodha, Mouez

    2015-01-01

    International audience; This article analyzes the long-term consequences of nuclear waste storage within a general equilibrium framework. The objective is to determine the conditions for which the storage of waste, and thus the transfer of externalities towards the future, can be optimal. These conditions could explain the implementation of intergenerational externalities, justifying an intertemporal Not In My Back Yard behaviour. We first show that the choice of the policy instruments determ...

  6. External cost assessment for nuclear fuel cycle

    Energy Technology Data Exchange (ETDEWEB)

    Park, Byung Heung [Korea National University of Transportation, Chungju (Korea, Republic of); Ko, Won Il [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-12-15

    Nuclear power is currently the second largest power supply method in Korea and the number of nuclear power plants are planned to be increased as well. However, clear management policy for spent fuels generated from nuclear power plants has not yet been established. The back-end fuel cycle, associated with nuclear material flow after nuclear reactors is a collection of technologies designed for the spent fuel management and the spent fuel management policy is closely related with the selection of a nuclear fuel cycle. Cost is an important consideration in selection of a nuclear fuel cycle and should be determined by adding external cost to private cost. Unlike the private cost, which is a direct cost, studies on the external cost are focused on nuclear reactors and not at the nuclear fuel cycle. In this research, external cost indicators applicable to nuclear fuel cycle were derived and quantified. OT (once through), DUPIC (Direct Use of PWR SF in CANDU), PWR-MOX (PWR PUREX reprocessing), and Pyro-SFR (SFR recycling with pyroprocessing) were selected as nuclear fuel cycles which could be considered for estimating external cost in Korea. Energy supply security cost, accident risk cost, and acceptance cost were defined as external cost according to precedent and estimated after analyzing approaches which have been adopted for estimating external costs on nuclear power generation.

  7. The ventilatory effect of external oscillation.

    Science.gov (United States)

    Isabey, D; Piquet, J

    1989-01-01

    High frequency ventilation (HFV) may be achieved by external oscillation (external HFV) applied around the chest wall (HFCWO) in large animals and humans, or over the entire body (HFBSO) in small animals, instead of being applied via the trachea (internal HFV). We present a synthesis of the results obtained with external HFV in both normal and bronchoconstricted subjects. Whereas external and internal HFV were found to be equivalent in terms of gas exchange in normal rats, external HFV was found to have a beneficial effect in bronchoconstricted rabbits, but internal HFV did not. From the frequency-oscillatory tidal volume relationship determined in normocapnic rabbits, HFBSO at 5 Hz was found to be the optimal frequency at which to ventilate with tidal volumes close to the dead space volume, and which was also shown to be the optimal volume to obtain normocapnia. Moreover, 5 Hz oscillations (HFCWO) at 20 ml and 40 ml superimposed on tidal breathing accelerated nitrogen washout, i.e., gas exchange in normal humans. Unfortunately, only oscillations with much smaller volumes (5-10 ml) were obtainable in COPD patients. Nevertheless, they produced a clear change in breathing pattern associated with a slight improvement in gas exchange and a potentially positive effect on inspiratory muscle fatigue. These results support the concept that non-invasive external HFV technique may be of use in assisting ventilation in bronchoconstricted subjects and may possibly replace conventional controlled ventilation, at least in subjects with high lung compliance, such as babies, neonates and normal adults.

  8. Negative ion source with external RF antenna

    Science.gov (United States)

    Leung, Ka-Ngo; Hahto, Sami K.; Hahto, Sari T.

    2007-02-13

    A radio frequency (RF) driven plasma ion source has an external RF antenna, i.e. the RF antenna is positioned outside the plasma generating chamber rather than inside. The RF antenna is typically formed of a small diameter metal tube coated with an insulator. An external RF antenna assembly is used to mount the external RF antenna to the ion source. The RF antenna tubing is wound around the external RF antenna assembly to form a coil. The external RF antenna assembly is formed of a material, e.g. quartz, which is essentially transparent to the RF waves. The external RF antenna assembly is attached to and forms a part of the plasma source chamber so that the RF waves emitted by the RF antenna enter into the inside of the plasma chamber and ionize a gas contained therein. The plasma ion source is typically a multi-cusp ion source. A converter can be included in the ion source to produce negative ions.

  9. Enhanced performance of dye-sensitized solar cells based on organic dopant incorporated PVDF-HFP/PEO polymer blend electrolyte with g-C3N4/TiO2 photoanode

    Science.gov (United States)

    Senthil, R. A.; Theerthagiri, J.; Madhavan, J.; Murugan, K.; Arunachalam, Prabhakarn; Arof, A. K.

    2016-10-01

    This work describes the effect of 2-aminopyrimidine (2-APY) on poly(vinylidinefluoride-co-hexafluoropropylene) (PVDF-HFP)/polyethylene oxide (PEO) blend polymer electrolyte along with binary iodide salts (tetrabutylammonium iodide (TBAI) and potassium iodide (KI)) and iodine (I2) were studied for enhancing the efficiency of the dye-sensitized solar cells (DSSCs) consisting of g-C3N4/TiO2 composite as photoanode. The g-C3N4 was synthesized from low cost urea by thermal condensation method. It was used as a precursor to synthesize the various weight percentage ratios (5%, 10% and 15%) of g-C3N4/TiO2 composites by wet-impregnation method. The pure and 2-APY incorporated PVDF-HFP/PEO polymer blend electrolytes were arranged by wet chemical process (casting method) using DMF as a solvent. The synthesized g-C3N4/TiO2 composites and polymer blend electrolytes were studied and analyzed by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The ionic conductivity values of the pure and 2-APY incorporated PVDF-HFP/PEO blend electrolytes were estimated to be 4.53×10-5 and 1.87×10-4 Scm-1 respectively. The UV-vis absorption spectroscopy was carried out for the pure and different wt% of g-C3N4/TiO2 composites coated FTO films after N3 dye-sensitization. The 10 wt% g-C3N4/TiO2 composite film showed a maximum absorption compared to the others. The DSSC assembled with 10 wt% g-C3N4/TiO2 as photoanode using the pure polymer blend electrolyte exhibited a power conversion efficiency (PCE) of 3.17% , which was superior than that of DSSC based pure TiO2 (2.46%). However, the PCE was increased to 4.73% for the DSSC assembled using 10 wt% g-C3N4/TiO2 as photoanode with 2-APY incorporated polymer blend electrolyte. Hence, the present study is a successful attempt to provide a new pathway to enhance the performance of DSSCs.

  10. Ion Transport and All-Solid Battery Characterization Studies on Mg2+-ION Conducting Nano-Composite Polymer Electrolyte (NCPEs):. (75PEO: 25MgSO4) + x MgO

    Science.gov (United States)

    Agrawal, R. C.; Mahipal, Y. K.; Sahu, Dinesh; Keshrawani, Priyanka

    2013-07-01

    Characterization of ion transport property on Mg2+-ion conducting Nano Composite Polymer Electrolytes (NCPEs): (75PEO: 25MgSO4) + x MgO, where x = 0, 1, 2, 3, 4, 5, 6, 8, 10, 12 wt. (%) has been reported. Solid Polymer Electrolyte (SPE) composition: [75PEO: 25MgSO4)], identified as the highest conducting film in an earlier study with room temperature conductivity σ ˜ 3.38 × 10-7 S /cm, has been used as Ist-phase host matrix and active filler MgO particles (micro / nano-dimension) as IInd - phase dispersoid. NCPE films have been prepared by a novel hot-press technique in place of the traditional solution cast method. Hot-press technique is recently receiving wider acceptability to cast polymeric electrolyte films due to the fact that it is a completely dry/solvent free/rapid/inexpensive procedure as compared to solution cast method. The Optimum Conducting Composition (OCC) of NCPE film has been identified from the filler-dependent conductivity measurements. As a consequence of dispersal of nano-size particles, the room temperature conductivity (σ) in NCPE OCC film increased by an order of magnitude i.e. σ ˜ 2.29 × 10-6 Scm-1. The quality of the film also improved substantially. The total ionic transference number (tion) and the cationic (Mg2+) transport number (t+) have been determined using dc polarization and a combined ac/dc technique respectively. A considerable increase in t+ could be achieved with the dispersal of nanoparticles. The confirmation of the salt-complexation in PEO polymer was done by FTIR spectroscopic studies. The temperature dependent conductivity measurements were carried out in NCPE OCC film and the activation energy (Ea) has been computed from `log σ - 1/T' Arrhenius plot. All-solid-state battery has been fabricated in the cell configuration: Mg (anode) // NCPE OCC film// MnO2 + C + Electrolyte (cathode), in which both the cathode and anode were in the form of thin pellet. The Open Circuit Voltage (OCV) ˜ 1.82 V was obtained. The

  11. Modified Atkins diet induces subacute selective ragged-red-fiber lysis in mitochondrial myopathy patients.

    Science.gov (United States)

    Ahola, Sofia; Auranen, Mari; Isohanni, Pirjo; Niemisalo, Satu; Urho, Niina; Buzkova, Jana; Velagapudi, Vidya; Lundbom, Nina; Hakkarainen, Antti; Muurinen, Tiina; Piirilä, Päivi; Pietiläinen, Kirsi H; Suomalainen, Anu

    2016-11-01

    Mitochondrial myopathy (MM) with progressive external ophthalmoplegia (PEO) is a common manifestation of mitochondrial disease in adulthood, for which there is no curative therapy. In mice with MM, ketogenic diet significantly delayed progression of the disease. We asked in this pilot study what effects high-fat, low-carbohydrate "modified Atkins" diet (mAD) had for PEO/MM patients and control subjects and followed up the effects by clinical, morphological, transcriptomic, and metabolomic analyses. All of our five patients, irrespective of genotype, showed a subacute response after 1.5-2 weeks of diet, with progressive muscle pain and leakage of muscle enzymes, leading to premature discontinuation of the diet. Analysis of muscle ultrastructure revealed selective fiber damage, especially in the ragged-red-fibers (RRFs), a MM hallmark. Two years of follow-up showed improvement of muscle strength, suggesting activation of muscle regeneration. Our results indicate that (i) nutrition can modify mitochondrial disease progression, (ii) dietary counseling should be part of MM care, (iii) short mAD is a tool to induce targeted RRF lysis, and (iv) mAD, a common weight-loss method, may induce muscle damage in a population subgroup.

  12. Application of PEO-AuNPs Based Polymer Composites for Visual Detection of Acrylamide%一种基于聚乙二醇单甲醚和纳米金的高分子复合材料在可视化检测丙烯酰胺中的应用

    Institute of Scientific and Technical Information of China (English)

    杨桂英; 赵鹏翔; 徐钦英; 周元林; 赖新春; 黄德顺

    2015-01-01

    建立了一种用聚乙二醇单甲醚稳定的纳米金(PEO-纳米金)可视化检测丙烯酰胺(AM)的新方法,并用透射电子显微镜镜、紫外可见光光度计、激光粒度分析仪对PEO-蚋米金进行测试分析.结果表明,该PEO-纳米金金核为19 nm的规则球体且分散均匀,颗粒整体(纳米金金核和表面稳定剂)粒径集中分布在40 nm.浓度为0.004 mg/mL的丙烯酰胺可使该PEO-纳米金发生团聚,胶体由红色变成紫色,浓度在0.004~0.032 mg/mL之间时,团聚程度随浓度的增加而增加,同时颗粒整体粒径依次增大到170 nm,250 nm,600 nm.而N,N-二甲基丙烯酰胺(DMAA)在相同条件下不能使PEO-纳米金发生团聚.因此,可用该方法简单、快速地实现丙烯酰胺选择性检测.

  13. Externalities - an analysis using the EU ExternE-results; Externaliteter - en analys utifraan EU:s ExternE-resultat

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-10-01

    The EU project ExternE quantified the externalities for the different energy technologies. In this work, the ExternE results are used in a MARKAL-analysis for the Nordic countries. The analysis does not go into detail, but gives some interesting indications: The external costs are not fully covered in the Nordic energy systems, the present taxes and charges are not high enough. The emissions from the energy systems would be strongly reduced, if taxes/environmental charges were set at the level ExternE calculate. The emissions from power production would be reduced most. Renewable energy sources and natural gas dominate the energy systems in the ExternE case.

  14. A rare case of complete bilateral ophthalmoplegia and ptosis.

    Science.gov (United States)

    Hall, Daniel John; Bazaraa, Talal

    2014-01-01

    We describe the case of an 85-year-old gentleman admitted with bilateral ptosis and complete bilateral ocular paralysis. Initial differential diagnoses included myasthenia gravis, diabetic cranial neuropathy, an ischaemic event and possible occult neoplasm. Investigations did not support any of the differentials and Miller Fisher syndrome (MFS) was considered. Anti-GQ1b IgG antibody was positive, supporting the possibility of anti-ganglioside syndrome. This gentleman was treated with intravenous immunoglobulin (IVIG) and made a full recovery.

  15. EFFECT OF PAA-PEO TO RHEOLOGICAL PROPERTIES OF AQUEOUS ZrO2 SUSPENSIONS%PAA-PEO对ZrO2-H2O悬浮液流变性能的影响

    Institute of Scientific and Technical Information of China (English)

    张浩; 李强; 郭露村

    2008-01-01

    利用一种新型的分散剂-梳型共聚物poly(acrylic acid)-poly(ethylene oxide)(PAA-PEO),研究了pH、分散剂的添加量及固含量对ZrO2-H2O悬浮液的流变性能的影响.结果表明:在pH为3、PAA-PEO的添加量为0.3wt%,zrO2-H2O悬浮液的粘度最低;固含量在31vol%以下时,浆料都保持稳定状态,随着固含量的增加,浆料的粘度也增加,当固含量达到33vol%时,浆料呈现出明显的剪切变稀行为.

  16. Internalizing Externalities through Payments for Environmental Services

    Directory of Open Access Journals (Sweden)

    Sudarsono Soedomo

    2012-08-01

    Full Text Available Forest ecosystems, including plantation forests, provide goods and services that are marketable and non-marketable. Positive externalities produced by forest ecosystems are rarely considered in pricing of marketable products that result in economic inefficiencies. Internalizing externalities is required to improve the economic efficiency. The traditional way to internalize an externality is by providing subsidies or imposing taxes. Recently, payments for environmental services  are receiving more attention as an instrument for internalizing externalities provided by forest ecosystems. This promising alternative to improve our environment needs to be studied more extensively. In this paper, it can be indicated theoretically that the Pigovian tax, as a traditional way of addressing environmental problems, is able to mimic the result derived from the employment of environmental services payment. The difference is that environmental services payment improves the welfare of environmental service producers, whereas the Pigovian tax reduces it. A positive Pigovian tax increases the optimal rotation, which is positively associated with environmental improvement, but certainly reduces forest owner's welfare. This difference should be taken into account in the public policymaking so that perverse incentive may be avoided. Payment for environmental services  as an additional income to forest growers, not as alternative source of income, is a potential tool to address simultaneously issues of environment and poverty that are frequently contested.Keywords: externalities, payments for environmental services, tax, perverse incentive, social welfare

  17. External-field-free magnetic biosensor

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yuanpeng; Wang, Yi; Klein, Todd; Wang, Jian-Ping, E-mail: jpwang@umn.edu [Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

    2014-03-24

    In this paper, we report a magnetic nanoparticle (MNP) detection scheme without the presence of any external magnetic field. The proposed magnetic sensor uses a patterned groove structure within the sensor so that no external magnetic field is needed to magnetize the MNPs. An example is given based on a giant magnetoresistance (GMR) sensing device with a spin valve structure. For this structure, the detection of MNPs located inside the groove and near the free layer is demonstrated under no external magnetic field. Micromagnetic simulations are performed to calculate the signal to noise level of this detection scheme. A maximum signal to noise ratio (SNR) of 18.6 dB from one iron oxide magnetic nanoparticle with 8 nm radius is achieved. As proof of concept, this external-field-free GMR sensor with groove structure of 200 nm × 200 nm is fabricated using a photo and an electron beam integrated lithography process. Using this sensor, the feasibility demonstration of the detection SNR of 9.3 dB is achieved for 30 μl magnetic nanoparticles suspension (30 nm iron oxide particles, 1 mg/ml). This proposed external-field-free sensor structure is not limited to GMR devices and could be applicable to other magnetic biosensing devices.

  18. External GSM phone calls now made simpler

    CERN Multimedia

    2007-01-01

    On 2 July, the IT/CS Telecom Service introduced a new service making external calls from CERN GSM phones easier. A specific prefix is no longer needed for calls outside CERN. External calls from CERN GSM phones are to be simplified. It is no longer necessary to use a special prefix to call an external number from the CERN GSM network.The Telecom Section of the IT/CS Group is introducing a new system that will make life easier for GSM users. It is no longer necessary to use a special prefix (333) to call an external number from the CERN GSM network. Simply dial the number directly like any other Swiss GSM customer. CERN currently has its own private GSM network with the Swiss mobile operator, Sunrise, covering the whole of Switzerland. This network was initially intended exclusively for calls between CERN numbers (replacing the old beeper system). A special system was later introduced for external calls, allowing them to pass thr...

  19. Atomic excitation and recombination in external fields

    Energy Technology Data Exchange (ETDEWEB)

    Nayfeh, M.H.; Clark, C.W.

    1985-01-01

    This volume offers a timely look at Rydberg states of atoms in external fields and dielectronic recombination. Each topic provides authoritative coverage, presents a fresh account of a flourishing field of current atomic physics and introduces new opportunities for discovery and development. Topics considered include electron-atom scattering in external fields; observations of regular and irregular motion as exemplified by the quadratic zeeman effect and other systems; Rydberg atoms in external fields and the Coulomb geometry; crossed-field effects in the absorption spectrum of lithium in a magnetic field; precise studies of static electric field ionization; widths and shapes of stark resonances in sodium above the saddle point; studies of electric field effects and barium autoionizing resonances; autoionization and dielectronic recombination in plasma electric microfields; dielectronic recombination measurements on multicharged ions; merged beam studies of dielectronic recombination; Rydberg atoms and dielectronic recombination in astrophysics; and observations on dielectronic recombination.

  20. External Tonehole Interactions in Woodwind Instruments

    CERN Document Server

    Lefebvre, Antoine; Kergomard, Jean

    2012-01-01

    The transfer matrix method is often used to calculate the input impedance of woodwind instruments but it ignores the possible influence of the radiated sound from toneholes on other open holes. In this paper, a method is proposed to account for external tonehole interactions. It is found that the external tonehole interactions increase the amount of radiated energy, reduce slightly the lower resonance frequencies, and modify significantly the response near and above the tonehole lattice cutoff frequency. The results of simulations with the Finite Element Method, as well as experimental measurements, are presented and compared to the calculation with the method presented in this paper, confirming that the external tonehole interactions play a significant role in woodwind instrument.