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Sample records for surface functionalization hrp

  1. The pathogenicity factor HrpF interacts with HrpA and HrpG to modulate type III secretion system (T3SS) function and t3ss expression in Pseudomonas syringae pv. averrhoi.

    Science.gov (United States)

    Huang, Yi-Chiao; Lin, Yuan-Chuen; Wei, Chia-Fong; Deng, Wen-Ling; Huang, Hsiou-Chen

    2016-09-01

    To ensure the optimal infectivity on contact with host cells, pathogenic Pseudomonas syringae has evolved a complex mechanism to control the expression and construction of the functional type III secretion system (T3SS) that serves as a dominant pathogenicity factor. In this study, we showed that the hrpF gene of P. syringae pv. averrhoi, which is located upstream of hrpG, encodes a T3SS-dependent secreted/translocated protein. Mutation of hrpF leads to the loss of bacterial ability on elicitation of disease symptoms in the host and a hypersensitive response in non-host plants, and the secretion or translocation of the tested T3SS substrates into the bacterial milieu or plant cells. Moreover, overexpression of hrpF in the wild-type results in delayed HR and reduced t3ss expression. The results of protein-protein interactions demonstrate that HrpF interacts directly with HrpG and HrpA in vitro and in vivo, and protein stability assays reveal that HrpF assists HrpA stability in the bacterial cytoplasm, which is reduced by a single amino acid substitution at the 67th lysine residue of HrpF with alanine. Taken together, the data presented here suggest that HrpF has two roles in the assembly of a functional T3SS: one by acting as a negative regulator, possibly involved in the HrpSVG regulation circuit via binding to HrpG, and the other by stabilizing HrpA in the bacterial cytoplasm via HrpF-HrpA interaction prior to the secretion and formation of Hrp pilus on the bacterial surface. © 2015 BSPP and John Wiley & Sons Ltd.

  2. Structure-function analysis of the HrpB2-HrcU interaction in the Xanthomonas citri type III secretion system.

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    Paola A Cappelletti

    Full Text Available Bacterial type III secretion systems deliver protein virulence factors to host cells. Here we characterize the interaction between HrpB2, a small protein secreted by the Xanthomonas citri subsp. citri type III secretion system, and the cytosolic domain of the inner membrane protein HrcU, a paralog of the flagellar protein FlhB. We show that a recombinant fragment corresponding to the C-terminal cytosolic domain of HrcU produced in E. coli suffers cleavage within a conserved Asn264-Pro265-Thr266-His267 (NPTH sequence. A recombinant HrcU cytosolic domain with N264A, P265A, T266A mutations at the cleavage site (HrcU(AAAH was not cleaved and interacted with HrpB2. Furthermore, a polypeptide corresponding to the sequence following the NPTH cleavage site also interacted with HrpB2 indicating that the site for interaction is located after the NPTH site. Non-polar deletion mutants of the hrcU and hrpB2 genes resulted in a total loss of pathogenicity in susceptible citrus plants and disease symptoms could be recovered by expression of HrpB2 and HrcU from extrachromossomal plasmids. Complementation of the ΔhrcU mutant with HrcU(AAAH produced canker lesions similar to those observed when complemented with wild-type HrcU. HrpB2 secretion however, was significantly reduced in the ΔhrcU mutant complemented with HrcU(AAAH, suggesting that an intact and cleavable NPTH site in HrcU is necessary for total functionally of T3SS in X. citri subsp. citri. Complementation of the ΔhrpB2 X. citri subsp. citri strain with a series of hrpB2 gene mutants revealed that the highly conserved HrpB2 C-terminus is essential for T3SS-dependent development of citrus canker symptoms in planta.

  3. Review of HRP Positions

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    Center for Reliability Studies

    2007-01-01

    The Department of Energy (DOE) Human Reliability Program (HRP), published as 10 CFR Part 712, is currently being reviewed and revised to address concerns identified during its implementation. Although these ''page changes'' primarily incorporate clarification of terms and language, the following discussion relates to broadening the definition of positions that require HRP certification that is found in {section}712.10.

  4. From bacterial avirulence genes to effector functions via the hrp delivery system: an overview of 25 years of progress in our understanding of plant innate immunity.

    Science.gov (United States)

    Mansfield, John W

    2009-11-01

    Cloning the first avirulence (avr) gene has led not only to a deeper understanding of gene-for-gene interactions in plant disease, but also to fundamental insights into the suppression of basal defences against microbial attack. This article (focusing on Pseudomonas syringae) charts the development of ideas and research progress over the 25 years following the breakthrough achieved by Staskawicz and coworkers. Advances in gene cloning technology underpinned the identification of both avr and hrp genes, the latter being required for the activation of the defensive hypersensitive reaction (HR) and pathogenicity. The delivery of Avr proteins through the type III secretion machinery encoded by hrp gene clusters was demonstrated, and the activity of the proteins inside plant cells as elicitors of the HR was confirmed. Key roles for avr genes in pathogenic fitness have now been established. The rebranding of Avr proteins as effectors, proteins that suppress the HR and cell wall-based defences, has led to the ongoing search for their targets, and is generating new insights into the co-ordination of plant resistance against diverse microbes. Bioinformatics-led analysis of effector gene distribution in genomes has provided a remarkable view of the interchange of effectors and also their functional domains, as the arms race of attack and defence drives the evolution of microbial pathogenicity. The application of our accrued knowledge for the development of disease control strategies is considered.

  5. Global analysis of the HrpL regulon in the plant pathogen Pseudomonas syringae pv. tomato DC3000 reveals new regulon members with diverse functions

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    The type III secretion system (T3SS) is required for virulence in the gram-negative plant pathogen Pseudomonas syringae pv. tomato DC3000. The alternative sigma factor HrpL directly regulates expression of T3SS genes via a consensus promoter sequence, often designated as the “hrp promoter.” Although...

  6. Alternative Sigma Factor HrpL of Pectobacterium carotovorum 35 is Important for the Development of Soft-rot Symptoms

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    Hyo-Song Nam

    2011-08-01

    Full Text Available A bacterial artificial chromosome library of Pectobacterium carotovorum 35 was constructed to characterize the genome and to sequence its hrp region. The hrp cluster of P. carotovorum 35 consisted of 26 open reading frames in five operons. A promoter-based green fluorescent protein technology was used to identify the genes regulated by the alternative sigma factor, HrpL, in P. carotovorum 35. The majority of the selected clones contained the hrpJ operon promoter sequence, which harbors a hrp box, but no putative hrp boxes were detected within the promoter sequences of two other hrpL-regulated genes encoding for pectate lyase and large repetitive protein. Although the promoters of five other hrp operons also contained hrp boxes, their expression was not HrpL-dependent in the promoter-based selection in E. coli. However, transcriptional analysis showed that expression from all operons harboring hrp boxes, except for the hrpN operon, was reduced significantly in the hrpL mutant. The severity of soft-rot symptoms when the hrpL mutant was applied to the surface of tobacco leaves, mimicking natural infection, was greatly attenuated. These results indicate that the hrpL gene of P. carotovorum 35 may be involved in the development of soft-rot symptoms.

  7. Negative Autogenous Control of the Master Type III Secretion System Regulator HrpL in Pseudomonas syringae

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    Christopher Waite

    2017-01-01

    Full Text Available The type III secretion system (T3SS is a principal virulence determinant of the model bacterial plant pathogen Pseudomonas syringae. T3SS effector proteins inhibit plant defense signaling pathways in susceptible hosts and elicit evolved immunity in resistant plants. The extracytoplasmic function sigma factor HrpL coordinates the expression of most T3SS genes. Transcription of hrpL is dependent on sigma-54 and the codependent enhancer binding proteins HrpR and HrpS for hrpL promoter activation. hrpL is oriented adjacently to and divergently from the HrpL-dependent gene hrpJ, sharing an intergenic upstream regulatory region. We show that association of the RNA polymerase (RNAP-HrpL complex with the hrpJ promoter element imposes negative autogenous control on hrpL transcription in P. syringae pv. tomato DC3000. The hrpL promoter was upregulated in a ΔhrpL mutant and was repressed by plasmid-borne hrpL. In a minimal Escherichia coli background, the activity of HrpL was sufficient to achieve repression of reconstituted hrpL transcription. This repression was relieved if both the HrpL DNA-binding function and the hrp-box sequence of the hrpJ promoter were compromised, implying dependence upon the hrpJ promoter. DNA-bound RNAP-HrpL entirely occluded the HrpRS and partially occluded the integration host factor (IHF recognition elements of the hrpL promoter in vitro, implicating inhibition of DNA binding by these factors as a cause of negative autogenous control. A modest increase in the HrpL concentration caused hypersecretion of the HrpA1 pilus protein but intracellular accumulation of later T3SS substrates. We argue that negative feedback on HrpL activity fine-tunes expression of the T3SS regulon to minimize the elicitation of plant defenses.

  8. Characterisation of Functional Surfaces

    DEFF Research Database (Denmark)

    Lonardo, P.M.; De Chiffre, Leonardo; Bruzzone, A.A.

    2004-01-01

    Characterisation of surfaces is of fundamental importance to control the manufacturing process and the functional performance of the part. Many applications concern contact and tribology problems, which include friction, wear and lubrication. This paper presents the techniques and instruments for...

  9. Genome-wide identification of HrpL-regulated genes in the necrotrophic phytopathogen Dickeya dadantii 3937.

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    Shihui Yang

    Full Text Available BACKGROUND: Dickeya dadantii is a necrotrophic pathogen causing disease in many plants. Previous studies have demonstrated that the type III secretion system (T3SS of D. dadantii is required for full virulence. HrpL is an alternative sigma factor that binds to the hrp box promoter sequence of T3SS genes to up-regulate their expression. METHODOLOGY/PRINCIPAL FINDINGS: To explore the inventory of HrpL-regulated genes of D. dadantii 3937 (3937, transcriptome profiles of wild-type 3937 and a hrpL mutant grown in a T3SS-inducing medium were examined. Using a cut-off value of 1.5, significant differential expression was observed in sixty-three genes, which are involved in various cellular functions such as type III secretion, chemotaxis, metabolism, regulation, and stress response. A hidden Markov model (HMM was used to predict candidate hrp box binding sites in the intergenic regions of 3937, including the promoter regions of HrpL-regulated genes identified in the microarray assay. In contrast to biotrophic phytopathgens such as Pseudomonas syringae, among the HrpL up-regulated genes in 3937 only those within the T3SS were found to contain a hrp box sequence. Moreover, direct binding of purified HrpL protein to the hrp box was demonstrated for hrp box-containing DNA fragments of hrpA and hrpN using the electrophoretic mobility shift assay (EMSA. In this study, a putative T3SS effector DspA/E was also identified as a HrpL-upregulated gene, and shown to be translocated into plant cells in a T3SS-dependent manner. CONCLUSION/SIGNIFICANCES: We provide the genome-wide study of HrpL-regulated genes in a necrotrophic phytopathogen (D. dadantii 3937 through a combination of transcriptomics and bioinformatics, which led to identification of several effectors. Our study indicates the extent of differences for T3SS effector protein inventory requirements between necrotrophic and biotrophic pathogens, and may allow the development of different strategies for

  10. AtHIPM, an ortholog of the apple HrpN-interacting protein, is a negative regulator of plant growth and mediates the growth-enhancing effect of HrpN in Arabidopsis.

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    Oh, Chang-Sik; Beer, Steven V

    2007-10-01

    HrpN (harpin) protein is critical to the virulence of the fire blight pathogen Erwinia amylovora in host plants like apple (Malus x domestica). Moreover, exogenous treatment of Arabidopsis (Arabidopsis thaliana), a nonhost plant, with partially purified HrpN enhances growth. To address the bases of the effects of HrpN in disease, we sought a HrpN-interacting protein(s) in apple, using a yeast two-hybrid assay. A single positive clone, designated HIPM (HrpN-interacting protein from Malus), was found. HIPM, a 6.5-kD protein, interacted with HrpN in yeast and in vitro. Deletion analysis showed that the N-terminal 198 of 403 amino acids of HrpN are required for interaction with HIPM. HIPM orthologs were found in Arabidopsis (AtHIPM) and rice (Oryza sativa; OsHIPM). HrpN also interacted with AtHIPM in yeast and in vitro. In silico analyses revealed that the three plant proteins contain putative signal peptides and putative transmembrane domains. We showed that both HIPM and AtHIPM have functional signal peptides, and green fluorescent protein-tagged HIPM and AtHIPM associated, in clusters, with plasma membranes. Both HIPM and AtHIPM are expressed constitutively; however, they are expressed more strongly in apple and Arabidopsis flowers than in leaves and stems. The size of AtHIPM knockout mutant plants of Arabidopsis was slightly larger than the wild-type plants. Interestingly, the knockout mutant did not exhibit enhanced plant growth in response to treatment with HrpN. Overexpression of AtHIPM conversely resulted in smaller plants. These results indicate that AtHIPM functions as a negative regulator of plant growth and mediates enhanced growth that results from treatment with HrpN.

  11. AtHIPM, an Ortholog of the Apple HrpN-Interacting Protein, Is a Negative Regulator of Plant Growth and Mediates the Growth-Enhancing Effect of HrpN in Arabidopsis1[C][OA

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    Oh, Chang-Sik; Beer, Steven V.

    2007-01-01

    HrpN (harpin) protein is critical to the virulence of the fire blight pathogen Erwinia amylovora in host plants like apple (Malus x domestica). Moreover, exogenous treatment of Arabidopsis (Arabidopsis thaliana), a nonhost plant, with partially purified HrpN enhances growth. To address the bases of the effects of HrpN in disease, we sought a HrpN-interacting protein(s) in apple, using a yeast two-hybrid assay. A single positive clone, designated HIPM (HrpN-interacting protein from Malus), was found. HIPM, a 6.5-kD protein, interacted with HrpN in yeast and in vitro. Deletion analysis showed that the N-terminal 198 of 403 amino acids of HrpN are required for interaction with HIPM. HIPM orthologs were found in Arabidopsis (AtHIPM) and rice (Oryza sativa; OsHIPM). HrpN also interacted with AtHIPM in yeast and in vitro. In silico analyses revealed that the three plant proteins contain putative signal peptides and putative transmembrane domains. We showed that both HIPM and AtHIPM have functional signal peptides, and green fluorescent protein-tagged HIPM and AtHIPM associated, in clusters, with plasma membranes. Both HIPM and AtHIPM are expressed constitutively; however, they are expressed more strongly in apple and Arabidopsis flowers than in leaves and stems. The size of AtHIPM knockout mutant plants of Arabidopsis was slightly larger than the wild-type plants. Interestingly, the knockout mutant did not exhibit enhanced plant growth in response to treatment with HrpN. Overexpression of AtHIPM conversely resulted in smaller plants. These results indicate that AtHIPM functions as a negative regulator of plant growth and mediates enhanced growth that results from treatment with HrpN. PMID:17704235

  12. Global regulatory networks control the hrp regulon of the gall-forming bacterium Pantoea agglomerans pv. gypsophilae.

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    Panijel, Mary; Chalupowicz, Laura; Sessa, Guido; Manulis-Sasson, Shulamit; Barash, Isaac

    2013-09-01

    Gall formation by Pantoea agglomerans pv. gypsophilae is dependent on the hypersensitive response and pathogenicity (hrp) system. Previous studies demonstrated that PagR and PagI, regulators of the quorum-sensing system, induce expression of the hrp regulatory cascade (i.e., hrpXY, hrpS, and hrpL) that activates the HrpL regulon. Here, we isolated the genes of the Gac/Rsm global regulatory pathway (i.e., gacS, gacA, rsmB, and csrD) and of the post-transcriptional regulator rsmA. Our results demonstrate that PagR and PagI also upregulate expression of the Gac/Rsm pathway. PagR acts as a transcriptional activator of each of the hrp regulatory genes and gacA in a N-butanoyl-L-homoserine lactone-dependent manner as shown by gel shift experiments. Mutants of the Gac/Rsm genes or overexpression of rsmA significantly reduced Pantoea agglomerans virulence and colonization of gypsophila. Overexpression of rsmB sRNA abolished gall formation, colonization, and hypersensitive reaction on nonhost plants and prevented transcription of the hrp regulatory cascade, indicating a lack of functional type III secretion system. Expression of rsmB sRNA in the background of the csrD null mutant suggests that CsrD may act as a safeguard for preventing excessive production of rsmB sRNA. Results presented indicate that the hrp regulatory cascade is controlled directly by PagR and indirectly by RsmA, whereas deficiency in RsmA activity is epistatic to PagR induction.

  13. Identification of 17 HrpX-regulated proteins including two novel type III effectors, XOC_3956 and XOC_1550, in Xanthomonas oryzae pv. oryzicola.

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    Xue, Xiao-bo; Zou, Li-fang; Ma, Wen-xiu; Liu, Zhi-yang; Chen, Gong-you

    2014-01-01

    The function of some hypothetical proteins, possibly regulated by key hrp regulators, in the pathogenicity of phytopathogenic bacteria remains largely unknown. In the present study, in silicon microarray data demonstrated that the expression of 17 HrpX-regulated protein (Xrp) genes of X. oryzae pv. oryzicola (Xoc), which causes bacterial leaf streak in rice, were either positively or negatively regulated by HrpX or/and HrpG. Bioinformatics analysis demonstrated that five Xrps possess a putative type III secretion (T3S) signal in the first 50 N-terminal amino acids, six xrp genes contain a PIP-box-like sequence (TTCGB-NX-TTCGB, 9 ≤ X ≤ 25) in the promoter regions, and two Xrps have both motifs. Twelve Xrps are widely conserved in Xanthomonas spp., whereas four are specific for X. oryzae (Xrp6) or Xoc (Xrp8, Xrp14 and Xrp17). In addition to the regulation by HrpG/HrpX, some of the 17 genes were also modulated by another hrp regulator HrpD6. Mutagenesis of these 17 genes indicated that five Xrps (Xrp1, Xrp2, Xrp5, Xrp8 and Xrp14) were required for full virulence and bacterial growth in planta. Immunoblotting assays and fusion with N-terminally truncated AvrXa10 indicated that Xrp3 and Xrp5 were secreted and translocated into rice cells through the type-III secretion system (T3S), suggesting they are novel T3S effectors. Our results suggest that Xoc exploits an orchestra of proteins that are regulated by HrpG, HrpX and HrpD6, and these proteins facilitate both infection and metabolism.

  14. Poly(ADP-ribose) Glycohydrolase and Poly(ADP-ribose)-interacting Protein Hrp38 Regulate Pattern Formation during Drosophila Eye Development

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    Ji, Yingbiao; Jarnik, Michael; Tulin, Alexei V.

    2013-01-01

    Drosophila Hrp38, a homolog of human hnRNP A1, has been shown to regulate splicing, but its function can be modified by poly(ADP-ribosyl)ation. Notwithstanding such findings, our understanding of the roles of poly(ADP-ribosyl)ated Hrp38 on development is limited. Here, we have demonstrated that Hrp38 is essential for fly eye development based on a rough-eye phenotype with disorganized ommatidia observed in adult escapers of the hrp38 mutant. We also observed that Poly(ADP-ribose) Glycohydrolase (Parg) loss-of-function, which caused increased Hrp38 poly(ADP-ribosyl)ation, also resulted in the rough-eye phenotype with disrupted ommatidial lattice and reduced number of photoreceptor cells. In addition, ectopic expression of DE-cadherin, which is required for retinal morphogenesis, fully rescued the rough-eye phenotype of the hrp38 mutant. Similarly, Parg mutant eye clones had decreased expression level of DE-cadherin with orientation defects, which is reminiscent of DE-cadherin mutant eye phenotype. Therefore, our results suggest that Hrp38 poly(ADP-ribosyl)ation controls eye pattern formation via regulation of DE-cadherin expression, a finding which has implications for understanding the pathogenic mechanisms of Hrp38-related Fragile X syndrome and PARP1-related retinal degeneration diseases. PMID:23711619

  15. Degradation-by-design: Surface modification with functional substrates that enhance the enzymatic degradation of carbon nanotubes.

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    Sureshbabu, Adukamparai Rajukrishnan; Kurapati, Rajendra; Russier, Julie; Ménard-Moyon, Cécilia; Bartolini, Isacco; Meneghetti, Moreno; Kostarelos, Kostas; Bianco, Alberto

    2015-12-01

    Biodegradation of carbon-based nanomaterials has been pursued intensively in the last few years, as one of the most crucial issues for the design of safe, clinically relevant conjugates for biomedical applications. In this paper it is demonstrated that specific functional molecules can enhance the catalytic activity of horseradish peroxidase (HRP) and xanthine oxidase (XO) for the degradation of carbon nanotubes. Two different azido coumarins and one cathecol derivative are linked to multi-walled carbon nanotubes (MWCNTs). These molecules are good reducing substrates and strong redox mediators to enhance the catalytic activity of HRP. XO, known to metabolize various molecules mainly in the mammalian liver, including human, was instead used to test the biodegradability of MWCNTs modified with an azido purine. The products of the biodegradation process are characterized by transmission electron microscopy and Raman spectroscopy. The results indicate that coumarin and catechol moieties have enhanced the biodegradation of MWCNTs compared to oxidized nanotubes, likely due to the capacity of these substrates to better interact with and activate HRP. Although azido purine-MWCNTs are degraded less effectively by XO than oxidized nanotubes, the data uncover the importance of XO in the biodegradation of carbon-nanomaterials leading to their better surface engineering for biomedical applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. NASA HRP Immunology Discipline - Use of Terrestrial Analogs

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    Crucian, Brian

    2014-01-01

    Due to the cost and operational constraints, as well as technical implementation limitations, it is desirous to perform relevant space physiology investigations first in terrestrial 'space analogs'. This is particularly true for initial investigations, which may then provide appropriate focus for subsequent flight investigations, or for mechanistic investigations that simply cannot be performed during spaceflight. Appropriate analog choice is extremely important. There are a wide variety of terrestrial space analogs, each relevant to a particular physiological discipline (or disciplines) and each with a particular fidelity (or lack thereof) to spaceflight, and each with unique operational constraints. The HRP Immunology Discipline is tasked with managing the HRP Risk concerning clinical risk for Astronaut crews related to spaceflight-associated immune dysregulation. Such dysregulation has been documented to occur during spaceflight, and found to persist for the duration of a 6-month ISS mission. Studies continue to characterize the onorbit phenomenon, but it generally consists of diminished immunocyte function, dysregulated cytokine profiles, and persistent herpesvirus reactivation. Causes are thought to synergistically include microgravity, psychological or physiological stress, radiation, and/or circadian misalignment. An appropriate terrestrial analog for immune dysregulation would replicate as many of these influences as possible. Such analogs may include clinostat or bioreactor cell culture (microgravity), hindlimb suspension (stress, fluid shifts, hypokinesis), or human deployment to remote or extreme environments (isolation, stress, circadian). Also, the laboratory setting may be used as an analog, or to augment analogs, such as sleep deprivation/misalignment or human centrifugation to replicate gravitational stress. As an appropriate example of a NASA Disciplines use of Terrestrial space analogs, this talk will discuss spaceflight associated immune

  17. Horseradish peroxidase immobilized on copper surfaces and applications in selective electrocatalysis of p-dihydroxybenzene

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chuntao, E-mail: tsyj1992@126.com [Department of Chemistry, Taiyuan Normal University, Taiyuan 030031 (China); Institute of Energy and Environmental Electrochemistry, Taiyuan Normal University, Taiyuan 030031 (China); Luo, Xiaoxiao [Department of Natural Science, Michigan State University, MI 48823,USA (United States); Jia, Zehui [Department of Chemistry, Taiyuan Normal University, Taiyuan 030031 (China); Institute of Energy and Environmental Electrochemistry, Taiyuan Normal University, Taiyuan 030031 (China); Shi, Qinghua; Zhu, Ritao [Department of Chemistry, Taiyuan Normal University, Taiyuan 030031 (China)

    2017-06-01

    Abstract: Horseradish Peroxidase (HRP) was immobilized on copper surfaces with the linker of L-Cysteine (L-Cys) self-assembled films to form Cu/L-Cys/HRP electrodes. The activity of HRP can be preserved by the Cu/L-Cys self-assembled films. The Cu/L-Cys/HRP electrodes can be used for the selective electrocatalytic oxidase of p-dihydroxybenzen in absent of H{sub 2}O{sub 2}. The optimum pH for electrocatalyzing p-dihydroxybenzen was 5.5 or 7.0, which corresponds to the isoelectric points of L-Cys and HRP, respectively. X-ray photoelectron spectroscopy (XPS) provided the evidence that L-Cys linked with Cu surface by the Cu− S bond. Fourier transform infrared spectroscopy (FTIR) analyses indicated that aromatic plane of p-dihydroxybenzen was connected parallel to porphyrin ring of heme in HRP. Quantum chemical calculation of density functional theory (DFT) revealed that symmetry of molecular structure and minimum space steric hindrance for p-dihydroxybenzen were benefit to combination with HRP. Moreover, the lowest energy of LUMO and most negative charges of oxygen atom on hydroxyl group of p-dihydroxybenzen were advantage to lose the hydrogen atom of hydroxyl group to be oxided.

  18. Vicinal surfaces for functional nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Tegenkamp, Christoph [Institut fuer Festkoerperphysik, Gottfried Wilhelm Leibniz Universitaet Hannover, Appelstrasse 2, D-30167 Hannover (Germany)], E-mail: tegenkamp@fkp.uni-hannover.de

    2009-01-07

    Vicinal surfaces are currently the focus of research. The regular arrangements of atomic steps on a mesoscopic scale reveal the possibility to functionalize these surfaces for technical applications, e.g. nanowires, catalysts, etc. The steps of the vicinal surface are well-defined defect structures of atomic size for nucleation of low-dimensional nanostructures. The concentration and therefore the coupling between the nanostructures can be tuned over a wide range by simply changing the inclination angle of the substrate. However, the coupling of these nano-objects to the substrate is just as important in controlling their electronic or chemical properties and making a functionality useable. On the basis of stepped insulating films, these aspects are fulfilled and will be considered in the first part of this review. Recent results for the epitaxial growth of wide bandgap insulating films (CaF{sub 2}, MgO, NaCl, BaSrO) on metallic and semiconducting vicinal substrates (Si(100), Ge(100), Ag(100)) will be presented. The change of the electronic structure, the adsorption behavior as well as the kinetics and energetics of color centers in the presence of steps is discussed. The successful bridging of the gap between the atomic and mesoscopic world, i.e. the functionalization of vicinal surfaces by nanostructures, is demonstrated in the second part by metal adsorption on semiconducting surfaces. For (sub)monolayer coverage these systems have in common that the surface states do not hybridize with the support, i.e. the semiconducting surfaces are insulating. Here I will focus on the latest results of macroscopic transport measurements on Pb quantum wires grown on vicinal Si(111) showing indeed a one-dimensional transport behavior. (topical review)

  19. Involvement of hrpX and hrpG in the Virulence of Acidovorax citrulli Strain Aac5, Causal Agent of Bacterial Fruit Blotch in Cucurbits

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    Xiaoxiao Zhang

    2018-03-01

    Full Text Available Acidovorax citrulli causes bacterial fruit blotch, a disease that poses a global threat to watermelon and melon production. Despite its economic importance, relatively little is known about the molecular mechanisms of pathogenicity and virulence of A. citrulli. Like other plant-pathogenic bacteria, A. citrulli relies on a type III secretion system (T3SS for pathogenicity. On the basis of sequence and operon arrangement analyses, A. citrulli was found to have a class II hrp gene cluster similar to those of Xanthomonas and Ralstonia spp. In the class II hrp cluster, hrpG and hrpX play key roles in the regulation of T3SS effectors. However, little is known about the regulation of the T3SS in A. citrulli. This study aimed to investigate the roles of hrpG and hrpX in A. citrulli pathogenicity. We found that hrpG or hrpX deletion mutants of the A. citrulli group II strain Aac5 had reduced pathogenicity on watermelon seedlings, failed to induce a hypersensitive response in tobacco, and elicited higher levels of reactive oxygen species in Nicotiana benthamiana than the wild-type strain. Additionally, we demonstrated that HrpG activates HrpX in A. citrulli. Moreover, transcription and translation of the type 3-secreted effector (T3E gene Aac5_2166 were suppressed in hrpG and hrpX mutants. Notably, hrpG and hrpX appeared to modulate biofilm formation. These results suggest that hrpG and hrpX are essential for pathogenicity, regulation of T3Es, and biofilm formation in A. citrulli.

  20. Covalent chemical functionalization enhances the biodegradation of graphene oxide

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    Kurapati, Rajendra; Bonachera, Fanny; Russier, Julie; Rajukrishnan Sureshbabu, Adukamparai; Ménard-Moyon, Cécilia; Kostarelos, Kostas; Bianco, Alberto

    2018-01-01

    Biodegradation of the graphene-based materials is an emerging issue due to their estimated widespread usage in different industries. Indeed, a few concerns have been raised about their biopersistence. Here, we propose the design of surface-functionalized graphene oxide (GO) with the capacity to degrade more effectively compared to unmodified GO using horseradish peroxidase (HRP). For this purpose, we have functionalized the surface of GO with two well-known substrates of HRP namely coumarin and catechol. The biodegradation of all conjugates has been followed by Raman, dynamic light scattering and electron microscopy. Molecular docking and gel electrophoresis have been carried out to gain more insights into the interaction between GO conjugates and HRP. Our studies have revealed better binding when GO is functionalized with coumarin or catechol compared to control GOs. All results prove that GO functionalized with coumarin and catechol moieties display a faster and more efficient biodegradation over GO.

  1. H2O2 sensing using HRP modified catalyst-free ZnO nanorods synthesized by RF sputtering

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    Srivastava, Amit; Kumar, Naresh; Singh, Priti; Singh, Sunil Kumar

    2017-06-01

    Catalyst-free ( 00 l) oriented ZnO nanorods (NRs) -based biosensor for the H2O2 sensing has been reported. The (002) oriented ZnO NRs as confirmed by X-ray diffraction were successfully grown on indium tin oxide (ITO) coated glass substrate by radio frequency (RF) sputtering technique without using any catalyst. Horseradish peroxidase (HRP) enzyme was immobilized on ZnO NRs by physical adsorption technique to prepare the biosensor. In this HRP/ZnO NR/ITO bioelectrode, nafion solution was added to form a tight membrane on surface. The prepared bioelectrode has been used for biosensing measurements by electrochemical analyzer. The electrochemical studies reveal that the prepared HRP/ZnO NR/ITO biosensor is highly sensitive to the detection of H2O2 over a linear range of 0.250-10 μM. The ZnO NR-based biosensor showed lower value of detection limit (0.125 μM) and higher sensitivity (13.40 µA/µM cm2) towards H2O2. The observed value of higher sensitivity attributed to larger surface area of ZnO nanostructure for effective loading of HRP besides its high electron communication capability. In addition, the biosensor also shows lower value of enzyme's kinetic parameter (Michaelis-Menten constant, K m) of 0.262 μM which indicates enhanced enzyme affinity of HRP to H2O2. The reported biosensor may be useful for various applications in biosensing, clinical, food, and beverage industry.

  2. Functionals of finite Riemann surfaces

    CERN Document Server

    Schiffer, Menahem

    1954-01-01

    This advanced monograph on finite Riemann surfaces, based on the authors' 1949-50 lectures at Princeton University, remains a fundamental book for graduate students. The Bulletin of the American Mathematical Society hailed the self-contained treatment as the source of ""a plethora of ideas, each interesting in its own right,"" noting that ""the patient reader will be richly rewarded."" Suitable for graduate-level courses, the text begins with three chapters that offer a development of the classical theory along historical lines, examining geometrical and physical considerations, existence theo

  3. Chelating ligands for nanocrystals' surface functionalization

    NARCIS (Netherlands)

    Querner, Claudia; Reiss, Peter; Bleuse, Joël; Pron, Adam

    2004-01-01

    A new family of ligands for the surface functionalization of CdSe nanocrystals is proposed, namely alkyl or aryl derivatives of carbodithioic acids (R-C(S)SH). The main advantages of these new ligands are as follows: they nearly quantitatively exchange the initial surface ligands (TOPO) in very mild

  4. Measuring the Plasmodium falciparum HRP2 protein in blood from artesunate-treated malaria patients predicts post-artesunate delayed hemolysis.

    Science.gov (United States)

    Ndour, Papa Alioune; Larréché, Sébastien; Mouri, Oussama; Argy, Nicolas; Gay, Frédérick; Roussel, Camille; Jauréguiberry, Stéphane; Perillaud, Claire; Langui, Dominique; Biligui, Sylvestre; Chartrel, Nathalie; Mérens, Audrey; Kendjo, Eric; Ghose, Aniruddha; Hassan, Md Mahtab Uddin; Hossain, Md Amir; Kingston, Hugh W F; Plewes, Katherine; Dondorp, Arjen M; Danis, Martin; Houzé, Sandrine; Bonnefoy, Serge; Thellier, Marc; Woodrow, Charles J; Buffet, Pierre A

    2017-07-05

    Artesunate, the recommended drug for severe malaria, rapidly clears the malaria parasite from infected patients but frequently induces anemia-called post-artesunate delayed hemolysis (PADH)-for which a simple predictive test is urgently needed. The underlying event in PADH is the expulsion of artesunate-exposed parasites from their host erythrocytes by pitting. We show that the histidine-rich protein 2 (HRP2) of the malaria parasite Plasmodium falciparum persists in the circulation of artesunate-treated malaria patients in Bangladesh and in French travelers who became infected with malaria in Africa. HRP2 persisted in whole blood (not plasma) of artesunate-treated patients with malaria at higher levels compared to quinine-treated patients. Using an optimized membrane permeabilization method, HRP2 was observed by immunofluorescence, Western blotting, and electron microscopy to persist in once-infected red blood cells from artesunate-treated malaria patients. HRP2 was deposited at the membrane of once-infected red blood cells in a pattern similar to that for ring erythrocyte surface antigen (RESA), a parasite invasion marker. On the basis of these observations, we developed a semiquantitative titration method using a widely available HRP2-based rapid diagnostic dipstick test. Positivity on this test using a 1:500 dilution of whole blood from artesunate-treated patients with malaria collected shortly after parasite clearance predicted subsequent PADH with 89% sensitivity and 73% specificity. These results suggest that adapting an existing HRP2-based rapid diagnostic dipstick test may enable prediction of PADH several days before it occurs in artesunate-treated patients with malaria. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  5. Ultrasensitive colorimetric immunoassay for hCG detection based on dual catalysis of Au@Pt core-shell nanoparticle functionalized by horseradish peroxidase

    Science.gov (United States)

    Wang, Weiguo; Zou, Yake; Yan, Jinwu; Liu, Jing; Chen, Huixiong; Li, Shan; Zhang, Lei

    2018-03-01

    In this paper, an ultrasensitive colorimetric biosensor for human chorionic gonadotrophin (hCG) detection was designed from bottom-up method based on the dual catalysis of the horseradish peroxidase (HRP) and Au@Pt nanoparticles (NPs) relative to H2O2-TEM system. HRP and monoclonal mouse anti-hCG antibody (β-submit, mAb1) were co-immobilized onto the Au@Pt NP surface to improve catalytic efficiency and specificity, which formed a dual functionalized Au@Pt-HRP probe with the mean size of 42.8 nm (D50). The colorimetric immunoassay was developed for the hCG detection, and the Au@Pt-HRP probe featured a higher sensitivity in the concentration range of 0.4-12.8 IU L- 1 with a low limit of detection (LOD) of 0.1 IU L- 1 compared with the LODs of 0.8 IU L- 1 for BA-ELISA and of 2.0 IU L- 1 for Au@Pt, which indicated that the Au@Pt-HRP probe possessed higher catalytic efficiency with 2.8-fold increase over Au@Pt and 33.8-fold increase over HRP. Also, the Au@Pt-HRP probe exhibited good precision and reproducibility, high specificity and acceptable accuracy with CV being less than 15%. The dual functionalized Au@Pt-HRP probe as a type of signal amplified method was firstly applied in the colorimetric immunoassay for the hCG detection.

  6. Selective functionalization of patterned glass surfaces

    NARCIS (Netherlands)

    Ploetz, E.; Visser, B.; Slingenbergh, W.; Evers, K.; Martinez-Martinez, D.; Pei, Y. T.; Feringa, B. L.; De Hosson, J. Th. M.; Cordes, T.; van Dorp, W. F.

    2014-01-01

    Tailored writing and specific positioning of molecules on nanostructures is a key step for creating functional materials and nano-optical devices, or interfaces for synthetic machines in various applications. We present a novel approach for the selective functionalization of patterned glass surfaces

  7. Adsorption of Wine Constituents on Functionalized Surfaces.

    Science.gov (United States)

    Mierczynska-Vasilev, Agnieszka; Smith, Paul A

    2016-10-18

    The adsorption of macromolecules on solid surfaces is of great importance in the field of nanotechnology, biomaterials, biotechnological, and food processes. In the field of oenology adsorption of wine macromolecules such as polyphenols, polysaccharides, and proteins is much less desirable on membrane materials because of fouling and reduced filtering performance. On the other hand, adsorption of these molecules on processing aids is very beneficial for achieving wine clarity and stability. In this article, the effect of surface chemical functionalities on the adsorption of white, rosé, and red wine constituents was evaluated. Allylamine, acrylic acid, and ethanol were selected as precursors for plasma polymerization in order to generate coatings rich in amine, carboxyl, and hydroxyl chemical groups, respectively. The surface chemical functionalities were characterized by X-ray photoelectron spectroscopy (XPS) and the ability of different surface chemical functionalities to adsorb wine constituents were characterized by quartz crystal microbalance with dissipation (QCM-D) and atomic force microscopy (AFM). The results demonstrated that the amine and carboxyl modified surfaces encourage adsorption of constituents from white wine. The hydroxyl modified surfaces have the ability to preferentially adsorb rosé wine constituents, whereas red wine adsorbed to the highest extent on acrylic acid surface.

  8. Adsorption of Wine Constituents on Functionalized Surfaces

    Directory of Open Access Journals (Sweden)

    Agnieszka Mierczynska-Vasilev

    2016-10-01

    Full Text Available The adsorption of macromolecules on solid surfaces is of great importance in the field of nanotechnology, biomaterials, biotechnological, and food processes. In the field of oenology adsorption of wine macromolecules such as polyphenols, polysaccharides, and proteins is much less desirable on membrane materials because of fouling and reduced filtering performance. On the other hand, adsorption of these molecules on processing aids is very beneficial for achieving wine clarity and stability. In this article, the effect of surface chemical functionalities on the adsorption of white, rosé, and red wine constituents was evaluated. Allylamine, acrylic acid, and ethanol were selected as precursors for plasma polymerization in order to generate coatings rich in amine, carboxyl, and hydroxyl chemical groups, respectively. The surface chemical functionalities were characterized by X-ray photoelectron spectroscopy (XPS and the ability of different surface chemical functionalities to adsorb wine constituents were characterized by quartz crystal microbalance with dissipation (QCM-D and atomic force microscopy (AFM. The results demonstrated that the amine and carboxyl modified surfaces encourage adsorption of constituents from white wine. The hydroxyl modified surfaces have the ability to preferentially adsorb rosé wine constituents, whereas red wine adsorbed to the highest extent on acrylic acid surface.

  9. Characterization of an hrp-aox-polyaniline-graphite composite biosensor

    Directory of Open Access Journals (Sweden)

    Ana Carolina O. Santana

    2014-12-01

    Full Text Available Nowadays there is an increasing demand to develop new and robust biosensors in order to detect low concentrations of different chemicals, in practical and small devices, giving fast and confident responses. The electrode material was a polyaniline-graphite-epoxy composite (PANI/GEC. Alcohol oxidase (AOX and horseradish peroxidase (HRP enzymes were immobilized and the responses were tested by cyclic voltammetry. The conductivities for the composites of graphite/polyaniline were determined. The cyclic voltammograms allowed detecting ethanol in pure diluted samples in a range from 0.036 to 2.62 M. Differential scanning calorimetry (DSC and thermal gravimetry analysis (TGA were used to verify the thermal characteristics of the composites (0, 10, 20, 30 and 100 % of graphite. The Imax value was determined for the dual enzyme biosensor (0.0724 mA, and the Kapp m  as 1.41 M (with R2 =0.9912.

  10. Response Surface Modeling Using Multivariate Orthogonal Functions

    Science.gov (United States)

    Morelli, Eugene A.; DeLoach, Richard

    2001-01-01

    A nonlinear modeling technique was used to characterize response surfaces for non-dimensional longitudinal aerodynamic force and moment coefficients, based on wind tunnel data from a commercial jet transport model. Data were collected using two experimental procedures - one based on modem design of experiments (MDOE), and one using a classical one factor at a time (OFAT) approach. The nonlinear modeling technique used multivariate orthogonal functions generated from the independent variable data as modeling functions in a least squares context to characterize the response surfaces. Model terms were selected automatically using a prediction error metric. Prediction error bounds computed from the modeling data alone were found to be- a good measure of actual prediction error for prediction points within the inference space. Root-mean-square model fit error and prediction error were less than 4 percent of the mean response value in all cases. Efficacy and prediction performance of the response surface models identified from both MDOE and OFAT experiments were investigated.

  11. Functions of proteoglycans at the cell surface

    DEFF Research Database (Denmark)

    Höök, M; Woods, A; Johansson, S

    1986-01-01

    sulphate helps to connect the intracellular cytoskeleton to the extracellular matrix in focal adhesions. This evidence includes: the co-localization of actin and heparan sulphate proteoglycan during the process of cell spreading, and in isolated focal adhesions; biochemical analyses of a hydrophobic......Proteoglycans (primarily heparan sulphate proteoglycans) are found at the surface of most adherent eukaryotic cells. Earlier studies suggest that these molecules can be associated with the cell surface principally by two different mechanisms. Proteoglycans may occur as membrane......-intercalated glycoproteins, where the core protein of the proteoglycan is anchored in the lipid interior of the plasma membrane, or they may be bound via the polysaccharide components of the molecule to specific anchoring proteins present at the cell surface. A number of functions have been proposed for cell surface...

  12. Functions of proteoglycans at the cell surface

    DEFF Research Database (Denmark)

    Höök, M; Woods, A; Johansson, S

    1986-01-01

    Proteoglycans (primarily heparan sulphate proteoglycans) are found at the surface of most adherent eukaryotic cells. Earlier studies suggest that these molecules can be associated with the cell surface principally by two different mechanisms. Proteoglycans may occur as membrane......-intercalated glycoproteins, where the core protein of the proteoglycan is anchored in the lipid interior of the plasma membrane, or they may be bound via the polysaccharide components of the molecule to specific anchoring proteins present at the cell surface. A number of functions have been proposed for cell surface......-associated proteoglycans, including: regulation of cell-substrate adhesion; regulation of cell proliferation; participation in the binding and uptake of extracellular components; and participation in the regulation of extracellular matrix formation. Evidence is discussed suggesting that the cell-associated heparan...

  13. SURFACE TEXTURE ANALYSIS FOR FUNCTIONALITY CONTROL

    DEFF Research Database (Denmark)

    De Chiffre, Leonardo; Andreasen, Jan Lasson; Tosello, Guido

    This document is used in connection with three exercises of 3 hours duration as a part of the course VISION ONLINE – One week course on Precision & Nanometrology. The exercises concern surface texture analysis for functionality control, in connection with three different case stories. This docume...... contains a short description of each case story, 3-D roughness parameters analysis and relation with the product’s functionality.......This document is used in connection with three exercises of 3 hours duration as a part of the course VISION ONLINE – One week course on Precision & Nanometrology. The exercises concern surface texture analysis for functionality control, in connection with three different case stories. This document...

  14. Permanent isolation surface barrier: Functional performance

    Energy Technology Data Exchange (ETDEWEB)

    Wing, N.R.

    1993-10-01

    This document presents the functional performance parameters for permanent isolation surface barriers. Permanent isolation surface barriers have been proposed for use at the Hanford Site (and elsewhere) to isolate and dispose of certain types of waste in place. Much of the waste that would be disposed of using in-place isolation techniques is located in subsurface structures, such as solid waste burial grounds, tanks, vaults, and cribs. Unless protected in some way, the wastes could be transported to the accessible environment via transport pathways, such as water infiltration, biointrusion, wind and water erosion, human interference, and/or gaseous release.

  15. Surface functionalization of dopamine coated iron oxide nanoparticles for various surface functionalities

    Energy Technology Data Exchange (ETDEWEB)

    Sherwood, Jennifer; Xu, Yaolin; Lovas, Kira [Chemical and Biological Engineering, The University of Alabama, Tuscaloosa , AL 35487 (United States); Qin, Ying [Alabama Innovation and Mentoring of Entrepreneurs, The University of Alabama, Tuscaloosa, AL 35487 (United States); Bao, Yuping, E-mail: ybao@eng.ua.edu [Chemical and Biological Engineering, The University of Alabama, Tuscaloosa , AL 35487 (United States)

    2017-04-01

    We present effective conjugation of four small molecules (glutathione, cysteine, lysine, and Tris(hydroxymethyl)aminomethane) onto dopamine-coated iron oxide nanoparticles. Conjugation of these molecules could improve the surface functionality of nanoparticles for more neutral surface charge at physiological pH and potentially reduce non-specific adsorption of proteins to nanoparticles surfaces. The success of conjugation was evaluated with dynamic light scattering by measuring the surface charge changes and Fourier transform infrared spectroscopy for surface chemistry analysis. The stability of dopamine-coated nanoparticles and the ability of conjugated nanoparticles to reduce the formation of protein corona were evaluated by measuring the size and charge of the nanoparticles in biological medium. This facile conjugation method opens up possibilities for attaching various surface functionalities onto iron oxide nanoparticle surfaces for biomedical applications.

  16. Surface functionalization of dopamine coated iron oxide nanoparticles for various surface functionalities

    International Nuclear Information System (INIS)

    Sherwood, Jennifer; Xu, Yaolin; Lovas, Kira; Qin, Ying; Bao, Yuping

    2017-01-01

    We present effective conjugation of four small molecules (glutathione, cysteine, lysine, and Tris(hydroxymethyl)aminomethane) onto dopamine-coated iron oxide nanoparticles. Conjugation of these molecules could improve the surface functionality of nanoparticles for more neutral surface charge at physiological pH and potentially reduce non-specific adsorption of proteins to nanoparticles surfaces. The success of conjugation was evaluated with dynamic light scattering by measuring the surface charge changes and Fourier transform infrared spectroscopy for surface chemistry analysis. The stability of dopamine-coated nanoparticles and the ability of conjugated nanoparticles to reduce the formation of protein corona were evaluated by measuring the size and charge of the nanoparticles in biological medium. This facile conjugation method opens up possibilities for attaching various surface functionalities onto iron oxide nanoparticle surfaces for biomedical applications.

  17. Fluorescence enhancement of CdTe quantum dots by HBcAb-HRP for sensitive detection of H2O2in human serum.

    Science.gov (United States)

    Gong, Tingting; Liu, Junfeng; Wu, Yiwei; Xiao, Yao; Wang, Xuehan; Yuan, Siqi

    2017-06-15

    A simple, high selective, ultra-sensitive and stable biosensor based on hepatitis B core antibody labeled with horseradish peroxidase (HBcAb-HRP) induced fluorescent enhancement of CdTe QDs for recognition of H 2 O 2 have been constructed. In this assay, sulfurs in HBcAb-HRP, which possess a strong affinity towards Cd 2+ , can improve greatly the recombination fluorescence of CdTe QDs by creating more radiative centers at CdTe/Cd-SR complex. Then, H 2 O 2 oxidizes Cd-S bonds in CdTe QDs to organic disulfide product (RS-SR), causing thioglycolic acid (TGA) and HBcAb-HRP detach from surface of CdTe QDs and thus leading to fluorescence quenching. Just with the addition of HBcAb-HRP, sensitivity of the new biosensor has been improved by near one order of magnitude as compared with CdTe QDs probe. Detection limit of HBcAb-HRP-CdTe QDs biosensor for determination of H 2 O 2 was 6.9×10 -8 mol L -1 (3σ/slope), and the excellent linear range was 1.0×10 -7 ~1.5×10 -4 molL -1 . By using sodium diethyldithiocarbamate (DDTC) and NH 4 OH as masking agents of Ag + , Hg 2+ and Cu 2+ , H 2 O 2 can be selectively detected in coexistence with Ag + , Hg 2+ and Cu 2+ , and the biosensor has been used to detect H 2 O 2 in human serum with satisfactory results. The superior properties of this biosensor showed great potential usage in more chemical and biological researches. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Functionalization and Polymerization on the CNT Surfaces

    KAUST Repository

    Albuerne, Julio

    2013-07-01

    In this review we focus on the current status of using carbon nanotube (CNT) as a filler for polymer nanocomposites. Starting with the historical background of CNT, its distinct properties and the surface functionalization of the nanotube, the three different surface polymerization techniques, namely grafting "from", "to" and "through/in between" were discussed. Wider focus has been given on "grafting from" surface initiated polymerizations, including atom transfer radical polymerization (ATRP), reversible addition fragmentation chain-transfer (RAFT) Polymerization, nitroxide mediated polymerization (NMP), ring opening polymerization (ROP) and other miscellaneous polymerization methods. The grafting "to" and "through / in between" also discussed and compared with grafting from polymerization. The merits and shortcomings of all three grafting methods were discussed and the bottleneck issue in grafting from method has been highlighted. Furthermore the current and potential future industrial applications were deliberated. Finally the toxicity issue of CNTs in the final product has been reviewed with the limited available literature knowledge. © 2013 Bentham Science Publishers.

  19. Chelating ligands for nanocrystals' surface functionalization.

    Science.gov (United States)

    Querner, Claudia; Reiss, Peter; Bleuse, Joël; Pron, Adam

    2004-09-22

    A new family of ligands for the surface functionalization of CdSe nanocrystals is proposed, namely alkyl or aryl derivatives of carbodithioic acids (R-C(S)SH). The main advantages of these new ligands are as follows: they nearly quantitatively exchange the initial surface ligands (TOPO) in very mild conditions; they significantly improve the resistance of nanocrystals against photooxidation because of their ability of strong chelate-type binding to metal atoms; their relatively simple preparation via Grignard intermediates facilitates the development of new bifunctional ligands containing, in addition to the anchoring carbodithioate group, a second function, which enables the grafting of molecules or macromolecules of interest on the nanocrystal surface. To give an example of this approach, we report, for the first time, the grafting of an electroactive oligomer from the polyaniline family-aniline tetramer-on CdSe nanocrystals after their functionalization with 4-formyldithiobenzoic acid. The grafting proceeds via a condensation reaction between the aldehyde group of the ligand and the terminal primary amine group of the tetramer. The resulting organic/inorganic hybrid exhibits complete extinction of the fluorescence of its constituents, indicating efficient charge or energy transfer between the organic and the inorganic semiconductors.

  20. SlyA regulates type III secretion system (T3SS) genes in parallel with the T3SS master regulator HrpL in Dickeya dadantii 3937.

    Science.gov (United States)

    Zou, Lifang; Zeng, Quan; Lin, Haiping; Gyaneshwar, Prasad; Chen, Gongyou; Yang, Ching-Hong

    2012-04-01

    The hypersensitive response and pathogenicity (hrp) genes of Dickeya dadantii 3937 encode a type III secretion system (T3SS) which is essential for its full virulence. Previous studies of the T3SS regulation in D. dadantii 3937 revealed that the expression of the hrp genes is regulated by a master regulator, HrpL, through the HrpX-HrpY-HrpS-HrpL and GacS-GacA-rsmB-RsmA pathways. In this work, we identified a novel regulator of the SlyA/MarR family, SlyA, which regulates hrp genes of the HrpL regulon in parallel with HrpL in D. dadantii. SlyA regulates the T3SS in a two-tier manner. It negatively regulates the expression of hrpL by downregulating hrpS and upregulating rsmA. Interestingly, concomitant with its downregulation of the hrpL, SlyA positively regulates the expression of hrpA and hrpN, two hrp genes located in the HrpL regulon. In contrast to Pectobacterium carotovorum, the expression of slyA is not controlled by ExpR and ExpI in D. dadantii 3937. We further show that SlyA is involved in controlling swimming motility and pellicle formation in D. dadantii 3937.

  1. Nanobody Based Immunoassay for Human Soluble Epoxide Hydrolase Detection Using Polymeric Horseradish Peroxidase (PolyHRP) for Signal Enhancement: The Rediscovery of PolyHRP?

    Science.gov (United States)

    Li, Dongyang; Cui, Yongliang; Morisseau, Christophe; Gee, Shirley J; Bever, Candace S; Liu, Xiangjiang; Wu, Jian; Hammock, Bruce D; Ying, Yibin

    2017-06-06

    Soluble epoxide hydrolase (sEH) is a potential pharmacological target for treating hypertension, vascular inflammation, cancer, pain, and multiple cardiovascular related diseases. A variable domain of the heavy chain antibody (termed single domain antibody (sdAb), nanobody, or VHH) possesses the advantages of small size, high stability, ease of genetic manipulation, and ability for continuous manufacture, making such nanobody a superior choice as an immunoreagent. In this work, we developed an ultrasensitive nanobody based immunoassay for human sEH detection using polymeric horseradish peroxidase (PolyHRP) for signal enhancement. Llama nanobodies against human sEH were used as the detection antibody in sandwich enzyme linked immunosorbent assays (ELISA) with polyclonal anti-sEH as the capture antibody. A conventional sandwich ELISA using a horseradish peroxidase (HRP) labeled anti-hemeagglutinin (HA) tag as the tracer showed a marginal sensitivity (0.0015 optical density (OD)·mL/ng) and limit of detection (LOD) of 3.02 ng/mL. However, the introduction of the PolyHRP as the tracer demonstrated a 141-fold increase in the sensitivity (0.21 OD·mL/ng) and 57-fold decrease in LOD (0.05 ng/mL). Systematic comparison of three different tracers in four ELISA formats demonstrated the overwhelming advantage of PolyHRP as a label for nanobody based immunoassay. This enhanced sEH immunoassay was further evaluated in terms of selectivity against other epoxide hydrolases and detection of the target protein in human tissue homogenate samples. Comparison with an enzyme activity based assay and a Western blot for sEH detection reveals good correlation with the immunoassay. This work demonstrates increased competiveness of nanobodies for practical sEH protein detection utilizing PolyHRP. It is worthwhile to rediscover the promising potential of PolyHRP in nanobody and other affinity based methods after its low-profile existence for decades.

  2. HRP Chief Scientist's Office: Conducting Research to Enable Deep Space Exploration

    Science.gov (United States)

    Charles, J. B.; Fogarty, J.; Vega, L.; Cromwell, R. L.; Haven, C. P.; McFather, J. C.; Savelev, I.

    2017-01-01

    The HRP Chief Scientist's Office sets the scientific agenda for the Human Research Program. As NASA plans for deep space exploration, HRP is conducting research to ensure the health of astronauts, and optimize human performance during extended duration missions. To accomplish this research, HRP solicits for proposals within the U.S., collaborates with agencies both domestically and abroad, and makes optimal use of ISS resources in support of human research. This session will expand on these topics and provide an opportunity for questions and discussion with the HRP Chief Scientist. Presentations in this session will include: NRA solicitations - process improvements and focus for future solicitations, Multilateral Human Research Panel for Exploration - future directions (MHRPE 2.0), Extramural liaisons - National Science Foundation (NSF) and Department of Defense (DOD), Standardized Measures for spaceflight, Ground-based Analogs - international collaborations, and International data sharing.

  3. Electron work function of stepped tungsten surfaces

    International Nuclear Information System (INIS)

    Krahl-Urban, B.

    1976-03-01

    The electron work function of tungsten (110) vicinal faces was measured with the aid of thermionic emission, and its dependence on the crystallographic orientation and the surface structure was investigated. The thermionic measurements were evaluated with the aid of the Richardson plot. The real temperature of the emitting tungsten faces was determined with an accuracy of +- 0.5% in the range between 2,200 and 2,800 K. The vicinal faces under investigation have been prepared with an orientation exactness of +- 15'. In the tungsten (110) vicinal faces under investigation, a strong dependence of the temperature coefficient d PHI/dT of the work function on the crystallographic orientation was found. A strong influence of the edge structure as well as of the step density on the temperature coefficient was observed. (orig./HPOE) [de

  4. Surface modification using peptide functionalized bilayers

    Science.gov (United States)

    Stroumpoulis, Dimitrios

    Engineering materials that are capable of supporting cell and tissue growth is a challenging task that involves identifying and incorporating biological signals into the material surfaces or scaffolds. One approach towards bioactivity in materials is to mimic the function of the extracellular matrix (ECM) by displaying adhesion promoting oligopeptides. Supported planar bilayers (SPB) are a good platform to study molecular interactions at interfaces, since transmembrane proteins and peptides can be incorporated in a biologically relevant environment with precise control over their concentration and presentation. SPBs can be formed on flat surfaces using the Langmuir-Blodgett (LB) technique or alternatively from vesicle solutions. The fusion of vesicles with solid substrates offers simplicity and enhanced bilayer deposition rates over the LB method, whereas it can also be used with convex and enclosed surfaces. Ellipsometry and a mass transport model were used to investigate the kinetics of SPB formation on silicon dioxide surfaces from 100 nm diameter 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) vesicles. For the range of concentrations studied, 0.025 to 0.380 mg/ml, a monotonic increase in the ellipsometric signal with time was observed until saturation and the adsorption rate constant was calculated. Further, a Monte Carlo model was used to simulate the SPB formation process and the computational results were successfully fit to the experimental data. Lipid vesicles displaying RGD peptide amphiphiles were fused onto glass coverslips to control the ability of these surfaces to support cell adhesion and growth. Cell adhesion was prevented on phosphatidylcholine bilayers in the absence of RGD, whereas cells adhered and spread in the presence of accessible RGD amphiphiles. This specific interaction between cells and RGD peptides was further explored in a concentration dependent fashion by creating a surface composition array using a microfluidic device. For the

  5. Plasmodium falciparum HRP2 ELISA for analysis of dried blood spot samples in rural Zambia.

    Science.gov (United States)

    Gibson, Lauren E; Markwalter, Christine F; Kimmel, Danielle W; Mudenda, Lwiindi; Mbambara, Saidon; Thuma, Philip E; Wright, David W

    2017-08-23

    Dried blood spots are commonly used for sample collection in clinical and non-clinical settings. This method is simple, and biomolecules in the samples remain stable for months at room temperature. In the field, blood samples for the study and diagnosis of malaria are often collected on dried blood spot cards, so development of a biomarker extraction and analysis method is needed. A simple extraction procedure for the malarial biomarker Plasmodium falciparum histidine-rich protein 2 (HRP2) from dried blood spots was optimized to achieve maximum extraction efficiency. This method was used to assess the stability of HRP2 in dried blood spots. Furthermore, 328 patient samples made available from rural Zambia were analysed for HRP2 using the developed method. These samples were collected at the initial administration of artemisinin-based combination therapy and at several points following treatment. An average extraction efficiency of 70% HRP2 with a low picomolar detection limit was achieved. In specific storage conditions HRP2 was found to be stable in dried blood spots for at least 6 months. Analysis of patient samples showed the method to have a sensitivity of 94% and a specificity of 89% when compared with microscopy, and trends in HRP2 clearance after treatment were observed. The dried blood spot ELISA for HRP2 was found to be sensitive, specific and accurate. The method was effectively used to assess biomarker clearance characteristics in patient samples, which prove it to be ideal for gaining further insight into the disease and epidemiological applications.

  6. A Novel Conductive Poly(3,4-ethylenedioxythiophene-BSA Film for the Construction of a Durable HRP Biosensor Modified with NanoAu Particles

    Directory of Open Access Journals (Sweden)

    Fangcheng Xu

    2016-03-01

    Full Text Available In this study, we have investigated the contribution of bovine serum albumin (BSA to the durability of the electrochemically synthesized poly(3,4-ethylenedioxythiophene (PEDOT film on a platinum (Pt electrode. The electrode was capable to effectively adsorb the nano Au particles (AuNPs to form a uniform layout, which was then able to immobilize the horseradish peroxidase (HRP to construct a functional HRP/AuNPs/PEDOT(BSA/Pt biosensor. Cyclic voltammetry was employed to evaluate the performance of the biosensor through the measurement of hydrogen peroxide. Our results revealed a satisfied linear correlation between the cathodic current and the concentration of H2O2. Furthermore, the addition of oxidized form of nicotinamide adenine dinucleotide, or NAD+, as the electron transfer mediator in the detection solution could dramatically enhance the sensitivity of detection by about 35.5%. The main advantages of the current biosensor are its durability, sensitivity, reliability, and biocompatibility.

  7. Erwinia amylovora expresses fast and simultaneously hrp/dsp virulence genes during flower infection on apple trees.

    Science.gov (United States)

    Pester, Doris; Milčevičová, Renáta; Schaffer, Johann; Wilhelm, Eva; Blümel, Sylvia

    2012-01-01

    Pathogen entry through host blossoms is the predominant infection pathway of the gram-negative bacterium Erwinia amylovora leading to manifestation of the disease fire blight. Like in other economically important plant pathogens, E. amylovora pathogenicity depends on a type III secretion system encoded by hrp genes. However, timing and transcriptional order of hrp gene expression during flower infections are unknown. Using quantitative real-time PCR analyses, we addressed the questions of how fast, strong and uniform key hrp virulence genes and the effector dspA/E are expressed when bacteria enter flowers provided with the full defense mechanism of the apple plant. In non-invasive bacterial inoculations of apple flowers still attached to the tree, E. amylovora activated expression of key type III secretion genes in a narrow time window, mounting in a single expression peak of all investigated hrp/dspA/E genes around 24-48 h post inoculation (hpi). This single expression peak coincided with a single depression in the plant PR-1 expression at 24 hpi indicating transient manipulation of the salicylic acid pathway as one target of E. amylovora type III effectors. Expression of hrp/dspA/E genes was highly correlated to expression of the regulator hrpL and relative transcript abundances followed the ratio: hrpA>hrpN>hrpL>dspA/E. Acidic conditions (pH 4) in flower infections led to reduced virulence/effector gene expression without the typical expression peak observed under natural conditions (pH 7). The simultaneous expression of hrpL, hrpA, hrpN, and the effector dspA/E during early floral infection indicates that speed and immediate effector transmission is important for successful plant invasion. When this delicate balance is disturbed, e.g., by acidic pH during infection, virulence gene expression is reduced, thus partly explaining the efficacy of acidification in fire blight control on a molecular level.

  8. Nanoparticle Surface Functionality Dictates Cellular and Systemic Toxicity

    DEFF Research Database (Denmark)

    Saei, Amir Ata; Yazdani, Mahdieh; Lohse, Samuel E.

    2017-01-01

    can greatly enhance subsequent therapeutic effects of NPs while diminishing their adverse side effects. In this review, we will focus on the effect of surface functionality on the cellular uptake and the transport of NPs by various subcellular processes.......Engineered nanoparticles (NPs) have opened new frontiers in therapeutics and diagnostics in recent years. The surface functionality of these nanoparticles often predominates their interactions with various biological components of human body, and proper selection or control of surface functionality...

  9. Stainless steel and polyethylene surfaces functionalized with silver nanoparticles.

    Science.gov (United States)

    Fialho, José Fq; Naves, Emiliane Aa; Bernardes, Patrícia C; Ferreira, Deusmaque C; Dos Anjos, Letícia D; Gelamo, Rogério V; de Sá, João Pn; de Andrade, Nélio J

    2018-01-01

    The antimicrobial effects of a stainless steel surface and a polyethylene surface functionalized with silver nanoparticles on the adhesion of different bacteria and the changes in physical and chemical characteristics of these surfaces that influence biofilm formation were evaluated. The functionalized surfaces of polyethylene and stainless steel were more hydrophobic than the control ones. The bacterial surfaces were hydrophilic. The adhesion of all bacteria was thermodynamically favorable (ΔG adhesion functionalized and control. The numbers of adhered cells of Staphylococcus aureus, Escherichia coli, and Pseudomonas fluorescens were not significantly different (p > 0.05) between the control and functionalized surfaces, reaching values compatible with biofilm formation. Analysis of atomic absorption spectrometry using water and reconstituted skim milk as simulants showed no release of Ag from the functionalized surfaces. In conclusion, the surfaces that were functionalized with silver nanoparticles were modified in hydrophobicity, roughness, and did not avoid bacterial adhesion. Additional studies of surfaces functionalized with silver nanoparticles should be conducted addressing the adsorption technique of silver nanoparticles on the stainless steel surface as well as in the preparation of the polyethylene surface to allow the contact of microorganism with the antimicrobial agent.

  10. Ellipsometry of functional organic surfaces and films

    CERN Document Server

    Hinrichs, Karsten

    2013-01-01

    Ellipsometry is the method of choice to determin the properties of surfaces and thin films. It provides comprehensive and sensitive characterization in a contactless and non-invasive measurements. This book gives a state-of-the-art survey of ellipsometric investigations of organic films and surfaces, from laboratory to synchrotron applications, with a special focus on in-situ use in processing environments and at solid-liquid interfaces.

  11. HrpNEa-induced deterrent effect on phloem feeding of the green ...

    Indian Academy of Sciences (India)

    State Ministry of Agriculture Key Laboratory for Monitoring and Management of Crop Pathogens and Insect Pests, Nanjing ... In response to HrpNEa, AtGSL5 expression and callose deposition were induced in the wild-type plant but not in atgsl5. .... as AtGSL1 through AtGSL12 in Arabidopsis (for review, see. Chen and Kim ...

  12. The hnRNP A1 homolog Hrp36 is essential for normal development ...

    Indian Academy of Sciences (India)

    2012-08-11

    Aug 11, 2012 ... [Singh AK and Lakhotia SC 2012 The hnRNP A1 homolog Hrp36 is essential for normal development, female fecundity, omega speckle formation and stress tolerance in ..... (b), freshly emerged flies (c) or within 3 days after emergence (d) when reared from egg hatching onwards at 30°C±1°C. Figure 1.

  13. NASA Human Research Program (HRP). International Space Station Medical Project (ISSMP)

    Science.gov (United States)

    Sams, Clarence F.

    2009-01-01

    This viewgraph presentation describes the various flight investigations performed on the International Space Station as part of the NASA Human Research Program (HRP). The evaluations include: 1) Stability; 2) Periodic Fitness Evaluation with Oxygen Uptake Measurement; 3) Nutrition; 4) CCISS; 5) Sleep; 6) Braslet; 7) Integrated Immune; 8) Epstein Barr; 9) Biophosphonates; 10) Integrated cardiovascular; and 11) VO2 max.

  14. Versatile Density Functionals for Computational Surface Science

    DEFF Research Database (Denmark)

    Wellendorff, Jess

    resampling techniques, thereby systematically avoiding problems with overfitting. The first ever density functional presenting both reliable accuracy and convincing error estimation is generated. The methodology is general enough to be applied to more complex functional forms with higher-dimensional fitting...... and resampling. This is illustrated by searching for meta-GGA type functionals that outperform current meta-GGAs while allowing for error estimation....

  15. Anterograde axonal transport and intercellular transfer of WGA-HRP in trigeminal-innervated sensory receptors of rat incisive papilla.

    Science.gov (United States)

    Chan, K Y; Byers, M R

    1985-04-08

    The ultrastructure and identification of WGA-HRP-labeled sensory receptors in the rat incisive papilla (the most anterior part of hard palate) were studied using semiserial thin sections. Various sensory receptors were organized according to three locations: dome region (ventral), chemosensory corpuscle region (medial to orifice of incisive canal), and lateral labium (apposing the incisive canal). In the dome region, the sensory receptors were localized in three sensory zones that were associated with surface ridges (one medial and two lateral). In each of these zones, intraepithelial receptor axons and Merkel receptors occurred in the epithelium, while simple unencapsulated corpuscles, glomerular-Meissner corpuscles, and incisive (encapsulated) corpuscles occurred in the lamina propria. In the chemosensory corpuscle region, chemosensory corpuscles and intraepithelial receptor axons were located in the epithelium, and incisive corpuscles were present in the lamina propria. In the lateral labium, only intraepithelial receptor axons were prominent. In all these sensory receptors, the preterminal axons and axon terminals were labeled with the tracer protein. In addition, some nonneuronal cells closely associated with the axon terminals were selectively labeled, e.g., terminal Schwann cells, lamellar Schwann cells, Merkel cells, corpuscular basal cells and chemosensory cells. Other adjacent cells were not labeled, e.g., unspecialized epithelial cells, capsular cells, corpuscular sustentacular cells, and fibroblasts. In both labeled axons and cells, WGA-HRP was incorporated into vesicles, tubules, and vacuolar organelles. The specific intercellular transfer of tracer protein may indicate trophic interactions between axon terminals and support cells in sensory receptors. The specific organization of multiple sensory receptors in the rat incisive papilla may provide a useful alternative system for studying somatosensory physiology.

  16. Green's functions potential fields on surfaces

    CERN Document Server

    Melnikov, Yuri A

    2017-01-01

    This book is comprehensive in its classical mathematical physics presentation, providing the reader with detailed instructions for obtaining Green's functions from scratch. Green's functions is an instrument easily accessible to practitioners who are engaged in design and exploitation of machines and structures in modern engineering practice. To date, there are no books available on the market that are devoted to the Green's function formalism for equations covered in this volume. The reader, with an undergraduate background in applied mathematics, can become an active user of the Green's function approach. For the first time, Green's functions are discussed for a specific class of problems dealing with potential fields induced in thin-wall structures and therefore, the reader will have first-hand access to a novel issue. This Work is accessible to researchers in applied mathematics, mechanics, and relevant disciplines such as engineering, as well as to upper level undergraduates and graduate students.

  17. HRP facility for fabrication of ITER vertical target divertor full scale plasma facing units

    International Nuclear Information System (INIS)

    Visca, Eliseo; Roccella, S.; Candura, D.; Palermo, M.; Rossi, P.; Pizzuto, A.; Sanguinetti, G.P.; Mancini, A.; Verdini, L.; Cacciotti, E.; Cerri, V.; Mugnaini, G.; Reale, A.; Giacomi, G.

    2015-01-01

    Highlights: • R&D activities for the manufacturing of ITER divertor high heat flux plasma-facing components (HHFC). • ENEA and Ansaldo have jointly manufactured several actively cooled monoblock mock-ups and prototypical components. • ENEA and ANSALDO NUCLEARE jointly participate to the European program for the qualification of the manufacturing technology for the ITER divertor IVT. • Successful manufacturing by HRP (Hot Radial Pressing) of first full-scale full-W armored IVT qualification prototype. - Abstract: ENEA and Ansaldo Nucleare S.p.A. (ANN) have being deeply involved in the European development activities for the manufacturing of the ITER Divertor Inner Vertical Target (IVT) plasma-facing components. During normal operation the heat flux deposited on the bottom segment of divertor is 5–10 MW/m 2 but the capability to remove up to 20 MW/m 2 during transient events of 10 s must also be demonstrated. In order to fulfill ITER requirements, ENEA has set up and widely tested a manufacturing process, named Hot Radial Pressing (HRP). The last challenge is now to fabricate full-scale prototypes of the IVT, aimed to be qualified for the next step, i.e. the series production. On the basis of the experience of manufacturing hundreds of small mock-ups, ENEA designed and installed a new suitable HRP facility. The objective of getting a final shaped plasma facing unit (PFU) that satisfies these requirements is an ambitious target because tolerances set by ITER/F4E are very tight. The setting-up of the equipment started with the fabrication of full scale and representative ‘dummies’ in which stainless steel instead of CFC or W was used for monoblocks. The results confirmed that dimensions were compliant with the required tolerances. The paper reports a brief description of the innovative HRP equipment and the dimensional check results after HRP of the first full-scale full-W PFU.

  18. HRP facility for fabrication of ITER vertical target divertor full scale plasma facing units

    Energy Technology Data Exchange (ETDEWEB)

    Visca, Eliseo, E-mail: eliseo.visca@enea.it [Unità Tecnica Fusione, ENEA C. R. Frascati, via E. Fermi 45, IT-00044 Frascati (Roma) (Italy); Roccella, S. [Unità Tecnica Fusione, ENEA C. R. Frascati, via E. Fermi 45, IT-00044 Frascati (Roma) (Italy); Candura, D.; Palermo, M. [Ansaldo Nucleare S.p.A., Corso Perrone 25, IT-16152 Genova (Italy); Rossi, P.; Pizzuto, A. [Unità Tecnica Fusione, ENEA C. R. Frascati, via E. Fermi 45, IT-00044 Frascati (Roma) (Italy); Sanguinetti, G.P. [Ansaldo Nucleare S.p.A., Corso Perrone 25, IT-16152 Genova (Italy); Mancini, A.; Verdini, L.; Cacciotti, E.; Cerri, V.; Mugnaini, G.; Reale, A.; Giacomi, G. [Unità Tecnica Fusione, ENEA C. R. Frascati, via E. Fermi 45, IT-00044 Frascati (Roma) (Italy)

    2015-10-15

    Highlights: • R&D activities for the manufacturing of ITER divertor high heat flux plasma-facing components (HHFC). • ENEA and Ansaldo have jointly manufactured several actively cooled monoblock mock-ups and prototypical components. • ENEA and ANSALDO NUCLEARE jointly participate to the European program for the qualification of the manufacturing technology for the ITER divertor IVT. • Successful manufacturing by HRP (Hot Radial Pressing) of first full-scale full-W armored IVT qualification prototype. - Abstract: ENEA and Ansaldo Nucleare S.p.A. (ANN) have being deeply involved in the European development activities for the manufacturing of the ITER Divertor Inner Vertical Target (IVT) plasma-facing components. During normal operation the heat flux deposited on the bottom segment of divertor is 5–10 MW/m{sup 2} but the capability to remove up to 20 MW/m{sup 2} during transient events of 10 s must also be demonstrated. In order to fulfill ITER requirements, ENEA has set up and widely tested a manufacturing process, named Hot Radial Pressing (HRP). The last challenge is now to fabricate full-scale prototypes of the IVT, aimed to be qualified for the next step, i.e. the series production. On the basis of the experience of manufacturing hundreds of small mock-ups, ENEA designed and installed a new suitable HRP facility. The objective of getting a final shaped plasma facing unit (PFU) that satisfies these requirements is an ambitious target because tolerances set by ITER/F4E are very tight. The setting-up of the equipment started with the fabrication of full scale and representative ‘dummies’ in which stainless steel instead of CFC or W was used for monoblocks. The results confirmed that dimensions were compliant with the required tolerances. The paper reports a brief description of the innovative HRP equipment and the dimensional check results after HRP of the first full-scale full-W PFU.

  19. Functional superhydrophobic surfaces made of Janus micropillars.

    Science.gov (United States)

    Mammen, Lena; Bley, Karina; Papadopoulos, Periklis; Schellenberger, Frank; Encinas, Noemí; Butt, Hans-Jürgen; Weiss, Clemens K; Vollmer, Doris

    2015-01-21

    We demonstrate the fabrication of superhydrophobic surfaces consisting of micropillars with hydrophobic sidewalls and hydrophilic tops, referred to as Janus micropillars. Therefore we first coat a micropillar array with a mono- or bilayer of polymeric particles, and merge the particles together to shield the top faces while hydrophobizing the walls. After removing the polymer film, the top faces of the micropillar arrays can be selectively chemically functionalised with hydrophilic groups. The Janus arrays remain superhydrophobic even after functionalisation as verified by laser scanning confocal microscopy. The robustness of the superhydrophobic behaviour proves that the stability of the entrapped air cushion is determined by the forces acting at the rim of the micropillars. This insight should stimulate a new way of designing super liquid-repellent surfaces with tunable liquid adhesion. In particular, combining superhydrophobicity with the functionalisation of the top faces of the protrusions with hydrophilic groups may have exciting new applications, including high-density microarrays for high-throughput screening of bioactive molecules, cells, or enzymes or efficient water condensation. However, so far chemical attachment of hydrophilic molecules has been accompanied with complete wetting of the surface underneath. The fabrication of superhydrophobic surfaces where the top faces of the protrusions can be selectively chemically post-functionalised with hydrophilic molecules, while retaining their superhydrophobic properties, is both promising and challenging.

  20. The use of hydrophobins to functionalize surfaces

    NARCIS (Netherlands)

    Scholtmeijer, K; Janssen, M.I.; van Leeuwen, M.B.M.; van Kooten, T.G.; Hektor, H.; Wosten, H.A B

    2004-01-01

    The physiochemical nature of surfaces can be changed by small proteins which are secreted by filamentous fungi. These proteins, called hydrophobins, are characterized by the presence of eight conserved cysteine residues and a typical hydropathy pattern. Upon contact with a hydrophilic–hydrophobic

  1. Surface-functionalized mesoporous carbon materials

    Science.gov (United States)

    Dai, Sheng; Gorka, Joanna; Mayes, Richard T.

    2016-02-02

    A functionalized mesoporous carbon composition comprising a mesoporous carbon scaffold having mesopores in which polyvinyl polymer grafts are covalently attached, wherein said mesopores have a size of at least 2 nm and up to 50 nm. Also described is a method for producing the functionalized mesoporous composition, wherein a reaction medium comprising a precursor mesoporous carbon, vinyl monomer, initiator, and solvent is subjected to sonication of sufficient power to result in grafting and polymerization of the vinyl monomer into mesopores of the precursor mesoporous carbon. Also described are methods for using the functionalized mesoporous carbon, particularly in extracting metal ions from metal-containing solutions.

  2. Surface functionalized hollow silica particles and composites

    KAUST Repository

    Rodionov, Valentin

    2017-05-26

    Composition comprising hollow spherical silica particles having outside particle walls and inside particle walls, wherein the particles have an average particle size of about 10 nm to about 500 nm and an average wall thickness of about 10 nm to about 50 nm; and wherein the particles are functionalized with at least one organic functional group on the outside particle wall, on the inside particle wall, or on both the outside and inside particle walls, wherein the organic functional group is in a reacted or unreacted form. The organic functional group can be epoxy. The particles can be mixed with polymer precursor or a polymer material such as epoxy to form a prepreg or a nanocomposite. Lightweight but strong materials can be formed. Low loadings of hollow particles can be used.

  3. Diamond surface functionalization with biomimicry – Amine surface tether and thiol moiety for electrochemical sensors

    Energy Technology Data Exchange (ETDEWEB)

    Sund, James B., E-mail: jim@jamessund.com [Department of Electrical and Computer Engineering, Duke University, Durham, NC (United States); Causey, Corey P. [Departments of Chemistry and Biochemistry, Duke University, Durham, NC (United States); Wolter, Scott D. [Department of Physics, Elon University, Elon, NC 27244 (United States); Parker, Charles B., E-mail: charles.parker@duke.edu [Department of Electrical and Computer Engineering, Duke University, Durham, NC (United States); Stoner, Brian R. [Department of Electrical and Computer Engineering, Duke University, Durham, NC (United States); Research Triangle Institute (RTI) International, Research Triangle Park, NC (United States); Toone, Eric J. [Departments of Chemistry and Biochemistry, Duke University, Durham, NC (United States); Glass, Jeffrey T. [Department of Electrical and Computer Engineering, Duke University, Durham, NC (United States)

    2014-05-01

    Highlights: • Diamond surfaces were functionalized with organic molecules using a novel approach. • Used biomimicry to select a molecule to bind NO, similar to the human body. • Molecular orbital theory predicted the molecule-analyte oxidation behavior. • A thiol moiety was attached to an amine surface tether on the diamond surface. • XPS analysis verified each surface functionalization step. - Abstract: The surface of conducting diamond was functionalized with a terminal thiol group that is capable of binding and detecting nitrogen–oxygen species. The functionalization process employed multiple steps starting with doped diamond films grown by plasma enhanced chemical vapor deposition followed by hydrogen termination and photochemical attachment of a chemically protected amine alkene. The surface tether was deprotected to reveal the amine functionality, which enabled the tether to be extended with surface chemistry to add a terminal thiol moiety for electrochemical sensing applications. Each step of the process was validated using X-ray photoelectron spectroscopy analysis.

  4. Superparamagnetic bead interactions with functionalized surfaces characterized by an immunomicroarray

    DEFF Research Database (Denmark)

    Skottrup, Peter Durand; Hansen, Mikkel Fougt; Moresco, Jacob Lange

    2010-01-01

    an immunomicroarray for systematic studies of the binding properties of 10 different micro-/nano-sized streptavidin-functionalized beads to a biotin substrate immobilized on SiO2 with or without surface modification SiO2 surface cleaning, immobilized substrate concentration and surface blocking conditions were...

  5. Surface energy and work function of elemental metals

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt; Rosengaard, N. M.

    1992-01-01

    We have performed an ab initio study of the surface energy and the work function for six close-packed surfaces of 40 elemental metals by means of a Green’s-function technique, based on the linear-muffin-tin-orbitals method within the tight-binding and atomic-sphere approximations. The results...... are in excellent agreement with a recent full-potential, all-electron, slab-supercell calculation of surface energies and work functions for the 4d metals. The present calculations explain the trend exhibited by the surface energies of the alkali, alkaline earth, divalent rare-earth, 3d, 4d, and 5d transition...

  6. The spectral function for Mott insulating surfaces

    CERN Document Server

    Manuel, L O; Feiguin, A E; Trumper, A E

    2003-01-01

    We show theoretically the fingerprints of short-range spiral magnetic correlations in the photoemission spectra of the Mott insulating ground states realized in the sq root 3 x sq root 3 triangular silicon surfaces K/Si(111)-B and SiC(0001). The calculated spectra present low-energy features of magnetic origin with a reduced dispersion approx 10-40 meV compared with the centre-of-mass spectra bandwidth approx 0.2-0.3 eV. Remarkably, we find that the quasiparticle (QP) signal survives only around the magnetic Goldstone modes. Our findings position these silicon surfaces as new candidates for investigation in the search for non-conventional QP excitations.

  7. The spectral function for Mott insulating surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Manuel, L O [Instituto de Fisica Rosario (CONICET) and Universidad Nacional de Rosario, Boulevard 27 de Febrero 210 bis (2000) Rosario (Argentina); Gazza, C J [Instituto de Fisica Rosario (CONICET) and Universidad Nacional de Rosario, Boulevard 27 de Febrero 210 bis (2000) Rosario (Argentina); Feiguin, A E [Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA (United States); Trumper, A E [Instituto de Fisica Rosario (CONICET) and Universidad Nacional de Rosario, Boulevard 27 de Febrero 210 bis (2000) Rosario (Argentina)

    2003-05-07

    We show theoretically the fingerprints of short-range spiral magnetic correlations in the photoemission spectra of the Mott insulating ground states realized in the {radical}3 x{radical} 3 triangular silicon surfaces K/Si(111)-B and SiC(0001). The calculated spectra present low-energy features of magnetic origin with a reduced dispersion {approx}10-40 meV compared with the centre-of-mass spectra bandwidth {approx}0.2-0.3 eV. Remarkably, we find that the quasiparticle (QP) signal survives only around the magnetic Goldstone modes. Our findings position these silicon surfaces as new candidates for investigation in the search for non-conventional QP excitations.

  8. The spectral function for Mott insulating surfaces

    International Nuclear Information System (INIS)

    Manuel, L O; Gazza, C J; Feiguin, A E; Trumper, A E

    2003-01-01

    We show theoretically the fingerprints of short-range spiral magnetic correlations in the photoemission spectra of the Mott insulating ground states realized in the √3 x√ 3 triangular silicon surfaces K/Si(111)-B and SiC(0001). The calculated spectra present low-energy features of magnetic origin with a reduced dispersion ∼10-40 meV compared with the centre-of-mass spectra bandwidth ∼0.2-0.3 eV. Remarkably, we find that the quasiparticle (QP) signal survives only around the magnetic Goldstone modes. Our findings position these silicon surfaces as new candidates for investigation in the search for non-conventional QP excitations

  9. Calculus on Surfaces with General Closest Point Functions

    KAUST Repository

    März, Thomas

    2012-01-01

    The closest point method for solving partial differential equations (PDEs) posed on surfaces was recently introduced by Ruuth and Merriman [J. Comput. Phys., 227 (2008), pp. 1943- 1961] and successfully applied to a variety of surface PDEs. In this paper we study the theoretical foundations of this method. The main idea is that surface differentials of a surface function can be replaced with Cartesian differentials of its closest point extension, i.e., its composition with a closest point function. We introduce a general class of these closest point functions (a subset of differentiable retractions), show that these are exactly the functions necessary to satisfy the above idea, and give a geometric characterization of this class. Finally, we construct some closest point functions and demonstrate their effectiveness numerically on surface PDEs. © 2012 Society for Industrial and Applied Mathematics.

  10. Container Surface Evaluation by Function Estimation

    Energy Technology Data Exchange (ETDEWEB)

    Wendelberger, James G. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-08-03

    Container images are analyzed for specific surface features, such as, pits, cracks, and corrosion. The detection of these features is confounded with complicating features. These complication features include: shape/curvature, welds, edges, scratches, foreign objects among others. A method is provided to discriminate between the various features. The method consists of estimating the image background, determining a residual image and post processing to determine the features present. The methodology is not finalized but demonstrates the feasibility of a method to determine the kind and size of the features present.

  11. Nanogold-polyaniline-nanogold microspheres-functionalized molecular tags for sensitive electrochemical immunoassay of thyroid-stimulating hormone

    Energy Technology Data Exchange (ETDEWEB)

    Cui Yuling; Chen Huafeng; Hou Li; Zhang Bing; Liu Bingqian; Chen Guonan [Ministry of Education Key Laboratory of Analysis and Detection for Food Safety, Fujian Province Key Laboratory of Analysis and Detection for Food Safety, Department of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350108 (China); Tang Dianping, E-mail: dianping.tang@fzu.edu.cn [Ministry of Education Key Laboratory of Analysis and Detection for Food Safety, Fujian Province Key Laboratory of Analysis and Detection for Food Safety, Department of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350108 (China)

    2012-08-13

    Highlights: Black-Right-Pointing-Pointer A novel immunosensing strategy was designed for detection of thyroid-stimulating hormone. Black-Right-Pointing-Pointer Using nanogold-polyaniline-nanogold microspheres as molecular tags. Black-Right-Pointing-Pointer Improvement of electrochemical activity of nanolabels. Black-Right-Pointing-Pointer Combination enzyme labels with nanolabels for signal amplification. - Abstract: Methods based on nanomaterial labels have been developed for electrochemical immunosensors and immunoassays, but most involved low sensitivity. Herein a novel class of molecular tags, nanogold-polyaniline-nanogold microspheres (GPGs), was first synthesized and functionalized with horseradish peroxidase-conjugated thyroid-stimulating hormone antibody (HRP-Ab{sub 2}) for sensitive electrochemical immunoassay of thyroid-stimulating hormone (TSH). X-ray diffraction, confocal Raman spectroscopy, scanning electron microscope and transmission electron microscope were employed to characterize the prepared GPGs. Based on a sandwich-type immunoassay format, the assay was performed in pH 5.0 acetate buffer containing 6.0 mmol L{sup -1} H{sub 2}O{sub 2} by using GPG-labeled HRP-Ab{sub 2} as molecular tags. Compared with pure polyaniline nanospheres and gold nanoparticles alone, the GPG hybrid nanostructures increased the surface area of the nanomaterials, and enhanced the immobilized amount of HRP-Ab{sub 2}. Several labeling protocols comprising HRP-Ab{sub 2}, nanogold particle-labeled HRP-Ab{sub 2}, and polyaniline nanospheres-labeled HRP-Ab{sub 2}, were also investigated for determination of TSH and improved analytical features were obtained by using the GPG-labeled HRP-Ab{sub 2}. With the GPG labeling method, the effects of incubation time and pH of acetate buffer on the current responses of the immunosensors were also studied. The strong attachment of HRP-Ab{sub 2} to the GPGs resulted in a good repeatability and intermediate precision down to 7%. The dynamic

  12. Macromolecular surface design: photopatterning of functional stable nitrile oxides.

    Science.gov (United States)

    Altintas, Ozcan; Glassner, Mathias; Rodriguez-Emmenegger, Cesar; Welle, Alexander; Trouillet, Vanessa; Barner-Kowollik, Christopher

    2015-05-04

    The efficient trapping of photogenerated thioaldehydes with functional shelf-stable nitrile oxides in a 1,3-dipolar cycloaddition is a novel and versatile photochemical strategy for polymer end-group functionalization and surface modification under mild and equimolar conditions. The modular ligation in solution was followed in detail by electrospray ionization mass spectrometry (ESI-MS). X-ray photoelectron spectroscopy (XPS) was employed to analyze the functionalized surfaces, whereas time-of-flight secondary-ion mass spectrometry (ToF-SIMS) confirmed the spatial control of the surface functionalization using a micropatterned shadow mask. Polymer brushes were grown from the surface in a spatially confined regime by surface-initiated atom transfer radical polymerization (SI-ATRP) as confirmed by TOF-SIMS, XPS as well as ellipsometry. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Erwinia amylovora expresses fast and simultaneously hrp/dsp virulence genes during flower infection on apple trees.

    Directory of Open Access Journals (Sweden)

    Doris Pester

    Full Text Available BACKGROUND: Pathogen entry through host blossoms is the predominant infection pathway of the gram-negative bacterium Erwinia amylovora leading to manifestation of the disease fire blight. Like in other economically important plant pathogens, E. amylovora pathogenicity depends on a type III secretion system encoded by hrp genes. However, timing and transcriptional order of hrp gene expression during flower infections are unknown. METHODOLOGY/PRINCIPAL FINDINGS: Using quantitative real-time PCR analyses, we addressed the questions of how fast, strong and uniform key hrp virulence genes and the effector dspA/E are expressed when bacteria enter flowers provided with the full defense mechanism of the apple plant. In non-invasive bacterial inoculations of apple flowers still attached to the tree, E. amylovora activated expression of key type III secretion genes in a narrow time window, mounting in a single expression peak of all investigated hrp/dspA/E genes around 24-48 h post inoculation (hpi. This single expression peak coincided with a single depression in the plant PR-1 expression at 24 hpi indicating transient manipulation of the salicylic acid pathway as one target of E. amylovora type III effectors. Expression of hrp/dspA/E genes was highly correlated to expression of the regulator hrpL and relative transcript abundances followed the ratio: hrpA>hrpN>hrpL>dspA/E. Acidic conditions (pH 4 in flower infections led to reduced virulence/effector gene expression without the typical expression peak observed under natural conditions (pH 7. CONCLUSION/SIGNIFICANCE: The simultaneous expression of hrpL, hrpA, hrpN, and the effector dspA/E during early floral infection indicates that speed and immediate effector transmission is important for successful plant invasion. When this delicate balance is disturbed, e.g., by acidic pH during infection, virulence gene expression is reduced, thus partly explaining the efficacy of acidification in fire blight

  14. Surface functionalization of silicone rubber for permanent adhesion improvement.

    Science.gov (United States)

    Roth, Jan; Albrecht, Victoria; Nitschke, Mirko; Bellmann, Cornelia; Simon, Frank; Zschoche, Stefan; Michel, Stefan; Luhmann, Claudia; Grundke, Karina; Voit, Brigitte

    2008-11-04

    The surface properties of poly(dimethyl siloxane) (PDMS) layers screen printed onto silicon wafers were studied after oxygen and ammonia plasma treatments and subsequent grafting of poly(ethylene -alt-maleic anhydride) (PEMA) using X-ray photoelectron spectroscopy (XPS), roughness analysis, and contact angle and electrokinetic measurements. In the case of oxygen-plasma-treated PDMS, a hydrophilic, brittle, silica-like surface layer containing reactive silanol groups was obtained. These surfaces indicate a strong tendency for "hydrophobic recovery" due to the surface segregation of low-molecular-weight PDMS species. The ammonia plasma treatment of PDMS resulted in the generation of amino-functional surface groups and the formation of a weak boundary layer that could be washed off by polar liquids. To avoid the loss of the plasma modification effect and to achieve stabilization of the mechanically instable, functionalized PDMS top layer, PEMA was subsequently grafted directly or after using gamma-APS as a coupling agent on the plasma-activated PDMS surfaces. In this way, long-time stable surface functionalization of PDMS was obtained. The reactivity of the PEMA-coated PDMS surface caused by the availability of anhydride groups could be controlled by the number of amino functional surface groups of the PDMS surface necessary for the covalent binding of PEMA. The higher the number of amino functional surface groups available for the grafting-to procedure, the lower the hydrophilicity and hence the lower the reactivity of the PEMA-coated PDMS surface. Additionally, pull-off tests were applied to estimate the effect of surface modification on the adhesion between the silicone rubber and an epoxy resin.

  15. Surface energy and work function of the light actinides

    DEFF Research Database (Denmark)

    Kollár, J.; Vitos, Levente; Skriver, Hans Lomholt

    1994-01-01

    We have calculated the surface energy and work function of the light actinides Fr, Ra, Ac, Th, Pa, U, Np, and Pu by means of a Green's-function technique based on the linear-muffin-tin-orbitals method within the tight-binding representation. In these calculations we apply an energy functional which...

  16. A Kind of Nanofluid Consisting of Surface-Functionalized Nanoparticles

    Directory of Open Access Journals (Sweden)

    Yang Xuefei

    2010-01-01

    Full Text Available Abstract A method of surface functionalization of silica nanoparticles was used to prepare a kind of stable nanofluid. The functionalization was achieved by grafting silanes directly to the surface of silica nanoparticles in silica solutions (both a commercial solution and a self-made silica solution were used. The functionalized nanoparticles were used to make nanofluids, in which well-dispersed nanoparticles can keep good stability. One of the unique characteristics of the nanofluids is that no deposition layer forms on the heated surface after a pool boiling process. The nanofluids have applicable prospect in thermal engineering fields with the phase-change heat transfer.

  17. The post-transcriptional regulator rsmA/csrA activates T3SS by stabilizing the 5' UTR of hrpG, the master regulator of hrp/hrc genes, in Xanthomonas.

    Science.gov (United States)

    Andrade, Maxuel O; Farah, Chuck S; Wang, Nian

    2014-02-01

    The RsmA/CsrA family of the post-transcriptional regulators of bacteria is involved in the regulation of many cellular processes, including pathogenesis. In this study, we demonstrated that rsmA not only is required for the full virulence of the phytopathogenic bacterium Xanthomonas citri subsp. citri (XCC) but also contributes to triggering the hypersensitive response (HR) in non-host plants. Deletion of rsmA resulted in significantly reduced virulence in the host plant sweet orange and a delayed and weakened HR in the non-host plant Nicotiana benthamiana. Microarray, quantitative reverse-transcription PCR, western-blotting, and GUS assays indicated that RsmA regulates the expression of the type 3 secretion system (T3SS) at both transcriptional and post-transcriptional levels. The regulation of T3SS by RsmA is a universal phenomenon in T3SS-containing bacteria, but the specific mechanism seems to depend on the interaction between a particular bacterium and its hosts. For Xanthomonads, the mechanism by which RsmA activates T3SS remains unknown. Here, we show that RsmA activates the expression of T3SS-encoding hrp/hrc genes by directly binding to the 5' untranslated region (UTR) of hrpG, the master regulator of the hrp/hrc genes in XCC. RsmA stabilizes hrpG mRNA, leading to increased accumulation of HrpG proteins and subsequently, the activation of hrp/hrc genes. The activation of the hrp/hrc genes by RsmA via HrpG was further supported by the observation that ectopic overexpression of hrpG in an rsmA mutant restored its ability to cause disease in host plants and trigger HR in non-host plants. RsmA also stabilizes the transcripts of another T3SS-associated hrpD operon by directly binding to the 5' UTR region. Taken together, these data revealed that RsmA primarily activates T3SS by acting as a positive regulator of hrpG and that this regulation is critical to the pathogenicity of XCC.

  18. The Post-transcriptional Regulator rsmA/csrA Activates T3SS by Stabilizing the 5′ UTR of hrpG, the Master Regulator of hrp/hrc Genes, in Xanthomonas

    Science.gov (United States)

    Andrade, Maxuel O.; Farah, Chuck S.; Wang, Nian

    2014-01-01

    The RsmA/CsrA family of the post-transcriptional regulators of bacteria is involved in the regulation of many cellular processes, including pathogenesis. In this study, we demonstrated that rsmA not only is required for the full virulence of the phytopathogenic bacterium Xanthomonas citri subsp. citri (XCC) but also contributes to triggering the hypersensitive response (HR) in non-host plants. Deletion of rsmA resulted in significantly reduced virulence in the host plant sweet orange and a delayed and weakened HR in the non-host plant Nicotiana benthamiana. Microarray, quantitative reverse-transcription PCR, western-blotting, and GUS assays indicated that RsmA regulates the expression of the type 3 secretion system (T3SS) at both transcriptional and post-transcriptional levels. The regulation of T3SS by RsmA is a universal phenomenon in T3SS-containing bacteria, but the specific mechanism seems to depend on the interaction between a particular bacterium and its hosts. For Xanthomonads, the mechanism by which RsmA activates T3SS remains unknown. Here, we show that RsmA activates the expression of T3SS-encoding hrp/hrc genes by directly binding to the 5′ untranslated region (UTR) of hrpG, the master regulator of the hrp/hrc genes in XCC. RsmA stabilizes hrpG mRNA, leading to increased accumulation of HrpG proteins and subsequently, the activation of hrp/hrc genes. The activation of the hrp/hrc genes by RsmA via HrpG was further supported by the observation that ectopic overexpression of hrpG in an rsmA mutant restored its ability to cause disease in host plants and trigger HR in non-host plants. RsmA also stabilizes the transcripts of another T3SS-associated hrpD operon by directly binding to the 5′ UTR region. Taken together, these data revealed that RsmA primarily activates T3SS by acting as a positive regulator of hrpG and that this regulation is critical to the pathogenicity of XCC. PMID:24586158

  19. The post-transcriptional regulator rsmA/csrA activates T3SS by stabilizing the 5' UTR of hrpG, the master regulator of hrp/hrc genes, in Xanthomonas.

    Directory of Open Access Journals (Sweden)

    Maxuel O Andrade

    2014-02-01

    Full Text Available The RsmA/CsrA family of the post-transcriptional regulators of bacteria is involved in the regulation of many cellular processes, including pathogenesis. In this study, we demonstrated that rsmA not only is required for the full virulence of the phytopathogenic bacterium Xanthomonas citri subsp. citri (XCC but also contributes to triggering the hypersensitive response (HR in non-host plants. Deletion of rsmA resulted in significantly reduced virulence in the host plant sweet orange and a delayed and weakened HR in the non-host plant Nicotiana benthamiana. Microarray, quantitative reverse-transcription PCR, western-blotting, and GUS assays indicated that RsmA regulates the expression of the type 3 secretion system (T3SS at both transcriptional and post-transcriptional levels. The regulation of T3SS by RsmA is a universal phenomenon in T3SS-containing bacteria, but the specific mechanism seems to depend on the interaction between a particular bacterium and its hosts. For Xanthomonads, the mechanism by which RsmA activates T3SS remains unknown. Here, we show that RsmA activates the expression of T3SS-encoding hrp/hrc genes by directly binding to the 5' untranslated region (UTR of hrpG, the master regulator of the hrp/hrc genes in XCC. RsmA stabilizes hrpG mRNA, leading to increased accumulation of HrpG proteins and subsequently, the activation of hrp/hrc genes. The activation of the hrp/hrc genes by RsmA via HrpG was further supported by the observation that ectopic overexpression of hrpG in an rsmA mutant restored its ability to cause disease in host plants and trigger HR in non-host plants. RsmA also stabilizes the transcripts of another T3SS-associated hrpD operon by directly binding to the 5' UTR region. Taken together, these data revealed that RsmA primarily activates T3SS by acting as a positive regulator of hrpG and that this regulation is critical to the pathogenicity of XCC.

  20. Identification of a putative cognate sensor kinase for the two-component response regulator HrpG, a key regulator controlling the expression of the hrp genes in Xanthomonas campestris pv. campestris.

    Science.gov (United States)

    Li, Rui-Fang; Lu, Guang-Tao; Li, Lei; Su, Hui-Zhao; Feng, Guo-fang; Chen, Ya; He, Yong-Qiang; Jiang, Bo-Le; Tang, Dong-Jie; Tang, Ji-Liang

    2014-07-01

    The bacterial phytopathogen Xanthomonas campestris pv. campestris (Xcc) relies on the hrp (hypersensitive response and pathogenicity) genes to cause disease and induce hypersensitive response (HR). The hrp genes of bacterial phytopathogens are divided into two groups. Xcc hrp genes belong to group II. It has long been known that the group II hrp genes are activated by an AraC-type transcriptional regulator whose expression is controlled by a two-component system (TCS) response regulator (named HrpG in Xcc). However, no cognate sensor kinase has yet been identified. Here, we present evidence showing that the Xcc open-reading frame XC_3670 encodes a TCS sensor kinase (named HpaS). Mutation of hpaS almost completely abolished the HR induction and virulence. Bacterial two-hybrid and protein pull-down assays revealed that HpaS physically interacted with HrpG. Phos-tag™ SDS-PAGE analysis showed that mutation in hpaS reduced markedly the phosphorylation of HrpG in vivo. These data suggest that HpaS and HrpG are most likely to form a TCS. We also showed that XC_3669 (named hpaR2), which is adjacent to hpaS and encodes a putative TCS response regulator, is required for full virulence but not HR induction. HpaR2 also physically interacted with HpaS, suggesting that HpaS may also form another TCS with HpaR2. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

  1. Surface plasma functionalization influences macrophage behavior on carbon nanowalls

    Energy Technology Data Exchange (ETDEWEB)

    Ion, Raluca [University of Bucharest, Department of Biochemistry and Molecular Biology, 91-95 Spl. Independentei, 050095 Bucharest (Romania); Vizireanu, Sorin [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor, PO Box MG-36, 077125, Magurele, Bucharest (Romania); Stancu, Claudia Elena [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor, PO Box MG-36, 077125, Magurele, Bucharest (Romania); Leibniz Institute for Plasma Science and Technology (INP Greifswald), Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany); Luculescu, Catalin [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor, PO Box MG-36, 077125, Magurele, Bucharest (Romania); Cimpean, Anisoara, E-mail: anisoara.cimpean@bio.unibuc.ro [University of Bucharest, Department of Biochemistry and Molecular Biology, 91-95 Spl. Independentei, 050095 Bucharest (Romania); Dinescu, Gheorghe [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor, PO Box MG-36, 077125, Magurele, Bucharest (Romania)

    2015-03-01

    The surfaces of carbon nanowall samples as scaffolds for tissue engineering applications were treated with oxygen or nitrogen plasma to improve their wettability and to functionalize their surfaces with different functional groups. X-ray photoelectron spectroscopy and water contact angle results illustrated the effective conversion of the carbon nanowall surfaces from hydrophobic to hydrophilic and the incorporation of various amounts of carbon, oxygen and nitrogen functional groups during the treatments. The early inflammatory responses elicited by un-treated and modified carbon nanowall surfaces were investigated by quantifying tumor necrosis factor-alpha and macrophage inflammatory protein-1 alpha released by attached RAW 264.7 macrophage cells. Scanning electron microscopy and fluorescence studies were employed to investigate the changes in macrophage morphology and adhesive properties, while MTT assay was used to quantify cell proliferation. All samples sustained macrophage adhesion and growth. In addition, nitrogen plasma treatment was more beneficial for cell adhesion in comparison with un-modified carbon nanowall surfaces. Instead, oxygen plasma functionalization led to increased macrophage adhesion and spreading suggesting a more activated phenotype, confirmed by elevated cytokine release. Thus, our findings showed that the chemical surface alterations which occur as a result of plasma treatment, independent of surface wettability, affect macrophage response in vitro. - Highlights: • N{sub 2} and O{sub 2} plasma treatments alter the CNW surface chemistry and wettability. • Cells seeded on CNW scaffolds are viable and metabolically active. • Surface functional groups, independent of surface wettability, affect cell response. • O{sub 2} plasma treatment of CNW leads to a more activated macrophage phenotype.

  2. Functionalized surfaces and nanostructures for nanotechnological applications

    Science.gov (United States)

    2003-01-01

    CMOS roadmap in sight at around 10 nm, combined with the uncertainly principal's limit of Von Neuman electronics at 2 nm, that merely making things smaller will not help us. Replacing CMOS transistors on a one for one basis with some type of nano device would have the effect of drastically increasing fabrication costs, while offering only a marginal improvement over current technologies. However, nanotechnology offers us a way out of this technological and financial cul-de-sac by building devices from the bottom up. Techniques such as self assembly, perhaps assisted by templates created by nano imprint lithography, a notable European success, combined with our understanding of the workings of polymers and molecules such as Rotoxane at the nanoscale open up a whole new host of possibilities. Whether it is avoiding Moore's second law by switching to plastic electronics, or using molecular electronics, our understanding of the behaviour of materials on the scale of small molecules allows a variety of alternative approaches, to produce smarter, cheaper devices. The new understandings will also allow us to design new architectures, with the end result that functionality will become a more valid measure of performance than transistor density or operations per second. 8. Nanotechnology is new It often comes as a surprise to learn that the Romans and Chinese were using nanoparticles thousands of years ago. Similarly, every time you light a match, fullerenes are produced. Degusssa have been producing carbon black, the substance that makes car tyres black and improves the wear resistance of the rubber, since the 1920s. Of course they were not aware that they were using nanotechnology, and as they had no control over particle size, or even any knowledge of the nanoscale they were not using nanotechnology as currently defined. What is new about nanotechnology is our ability to not only see, and manipulate matter on the nanoscale, but our understanding of atomic scale interactions

  3. Diamond surface functionalization with biomimicry - Amine surface tether and thiol moiety for electrochemical sensors

    Science.gov (United States)

    Sund, James B.; Causey, Corey P.; Wolter, Scott D.; Parker, Charles B.; Stoner, Brian R.; Toone, Eric J.; Glass, Jeffrey T.

    2014-05-01

    The surface of conducting diamond was functionalized with a terminal thiol group that is capable of binding and detecting nitrogen-oxygen species. The functionalization process employed multiple steps starting with doped diamond films grown by plasma enhanced chemical vapor deposition followed by hydrogen termination and photochemical attachment of a chemically protected amine alkene. The surface tether was deprotected to reveal the amine functionality, which enabled the tether to be extended with surface chemistry to add a terminal thiol moiety for electrochemical sensing applications. Each step of the process was validated using X-ray photoelectron spectroscopy analysis.

  4. Low work function of the Ca2N surface

    NARCIS (Netherlands)

    Uijttewaal, M.A.; de Wijs, G. A.; Groot, R.A. de

    2004-01-01

    Polymer diodes require cathodes that do not corrode the polymer but do have low work function to minimize the electron injection barrier. First-principles calculations demonstrate that the work function of the (1000) surface of the compound Ca2N is half an eV lower than that of the elemental metal

  5. Piezotransistive GaN microcantilevers based surface work function measurements

    Science.gov (United States)

    Bayram, Ferhat; Khan, Digangana; Li, Hongmei; Maksudul Hossain, Md.; Koley, Goutam

    2018-04-01

    Surface work function (SWF) measurements using a piezotransistive III–nitride cantilever has been demonstrated on multiple surfaces. The minimum detectable surface potential change of 10 mV was achieved with a signal to noise ratio of 3. This method was applied to determine the surface potential changes due to exposure of 5 ppm NO2 in graphene and In2O3 thin film, simultaneously with conductivity changes. The potentiometric measurements yielded 100 and 80 mV potential changes in SWFs of graphene and In2O3 respectively, which matches very well with experimental data published earlier indicating the efficacy of this readily miniaturizable measurement technique.

  6. Superhydrophobic surfaces: from natural to biomimetic to functional.

    Science.gov (United States)

    Guo, Zhiguang; Liu, Weimin; Su, Bao-Lian

    2011-01-15

    Nature is the creation of aesthetic functional systems, in which many natural materials have vagarious structures. Inspired from nature, such as lotus leaf, butterfly' wings, showing excellent superhydrophobicity, scientists have recently fabricated a lot of biomimetic superhydrophobic surfaces by virtue of various smart and easy routes. Whilst, many examples, such as lotus effect, clearly tell us that biomimicry is dissimilar to a simple copying or duplicating of biological structures. In this feature article, we review the recent studies in both natural superhydrophobic surfaces and biomimetic superhydrophobic surfaces, and highlight some of the recent advances in the last four years, including the various smart routes to construct rough surfaces, and a lot of chemical modifications which lead to superhydrophobicity. We also review their functions and applications to date. Finally, the promising routes from biomimetic superhydrophobic surfaces in the next are proposed. Copyright © 2010 Elsevier Inc. All rights reserved.

  7. Surface Functionalization of Thin-Film Composite Membranes with Copper Nanoparticles for Antimicrobial Surface Properties

    KAUST Repository

    Ben-Sasson, Moshe

    2014-01-07

    Biofouling is a major operational challenge in reverse osmosis (RO) desalination, motivating a search for improved biofouling control strategies. Copper, long known for its antibacterial activity and relatively low cost, is an attractive potential biocidal agent. In this paper, we present a method for loading copper nanoparticles (Cu-NPs) on the surface of a thin-film composite (TFC) polyamide RO membrane. Cu-NPs were synthesized using polyethyleneimine (PEI) as a capping agent, resulting in particles with an average radius of 34 nm and a copper content between 39 and 49 wt.%. The positive charge of the Cu-NPs imparted by the PEI allowed a simple electrostatic functionalization of the negatively charged RO membrane. We confirmed functionalization and irreversible binding of the Cu-NPs to the membrane surface with SEM and XPS after exposing the membrane to bath sonication. We also demonstrated that Cu-NP functionalization can be repeated after the Cu-NPs dissolve from the membrane surface. The Cu-NP functionalization had minimal impact on the intrinsic membrane transport parameters. Surface hydrophilicity and surface roughness were also maintained, and the membrane surface charge became positive after functionalization. The functionalized membrane exhibited significant antibacterial activity, leading to an 80-95% reduction in the number of attached live bacteria for three different model bacterial strains. Challenges associated with this functionalization method and its implementation in RO desalination are discussed. © 2013 American Chemical Society.

  8. Electrochemical characterization of organosilane-functionalized nanostructured ITO surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Pruna, R., E-mail: rpruna@el.ub.edu; Palacio, F.; López, M. [SIC, Departament d' Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain); Pérez, J. [Nanobioengineering Group, Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac 15-21, E-08028 Barcelona (Spain); Mir, M. [Nanobioengineering Group, Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac 15-21, E-08028 Barcelona (Spain); Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Monforte de Lemos 3-5 Pabellón 11, E-28029 Madrid (Spain); Blázquez, O.; Hernández, S.; Garrido, B. [MIND-IN" 2UB, Departament d' Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain)

    2016-08-08

    The electroactivity of nanostructured indium tin oxide (ITO) has been investigated for its further use in applications such as sensing biological compounds by the analysis of redox active molecules. ITO films were fabricated by using electron beam evaporation at different substrate temperatures and subsequently annealed for promoting their crystallization. The morphology of the deposited material was monitored by scanning electron microscopy, confirming the deposition of either thin films or nanowires, depending on the substrate temperature. Electrochemical surface characterization revealed a 45 % increase in the electroactive surface area of nanostructured ITO with respect to thin films, one third lower than the geometrical surface area variation determined by atomic force microscopy. ITO surfaces were functionalized with a model organic molecule known as 6-(ferrocenyl)hexanethiol. The chemical attachment was done by means of a glycidoxy compound containing a reactive epoxy group, the so-called 3-glycidoxypropyltrimethoxy-silane. ITO functionalization was useful for determining the benefits of nanostructuration on the surface coverage of active molecules. Compared to ITO thin films, an increase in the total peak height of 140 % was observed for as-deposited nanostructured electrodes, whereas the same measurement for annealed electrodes resulted in an increase of more than 400 %. These preliminary results demonstrate the ability of nanostructured ITO to increase the surface-to-volume ratio, conductivity and surface area functionalization, features that highly benefit the performance of biosensors.

  9. Electrochemical characterization of organosilane-functionalized nanostructured ITO surfaces

    International Nuclear Information System (INIS)

    Pruna, R.; Palacio, F.; López, M.; Pérez, J.; Mir, M.; 2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain))" data-affiliation=" (MIND-IN2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain))" >Blázquez, O.; 2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain))" data-affiliation=" (MIND-IN2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain))" >Hernández, S.; 2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain))" data-affiliation=" (MIND-IN2UB, Departament d'Enginyeries: Electrònica, Universitat de Barcelona, C/ Martí i Franquès 1, E-08028 Barcelona (Spain))" >Garrido, B.

    2016-01-01

    The electroactivity of nanostructured indium tin oxide (ITO) has been investigated for its further use in applications such as sensing biological compounds by the analysis of redox active molecules. ITO films were fabricated by using electron beam evaporation at different substrate temperatures and subsequently annealed for promoting their crystallization. The morphology of the deposited material was monitored by scanning electron microscopy, confirming the deposition of either thin films or nanowires, depending on the substrate temperature. Electrochemical surface characterization revealed a 45 % increase in the electroactive surface area of nanostructured ITO with respect to thin films, one third lower than the geometrical surface area variation determined by atomic force microscopy. ITO surfaces were functionalized with a model organic molecule known as 6-(ferrocenyl)hexanethiol. The chemical attachment was done by means of a glycidoxy compound containing a reactive epoxy group, the so-called 3-glycidoxypropyltrimethoxy-silane. ITO functionalization was useful for determining the benefits of nanostructuration on the surface coverage of active molecules. Compared to ITO thin films, an increase in the total peak height of 140 % was observed for as-deposited nanostructured electrodes, whereas the same measurement for annealed electrodes resulted in an increase of more than 400 %. These preliminary results demonstrate the ability of nanostructured ITO to increase the surface-to-volume ratio, conductivity and surface area functionalization, features that highly benefit the performance of biosensors.

  10. Functionalized polymer film surfaces via surface-initiated atom transfer radical polymerization

    International Nuclear Information System (INIS)

    Hu, Y.; Li, J.S.; Yang, W.T.; Xu, F.J.

    2013-01-01

    The ability to manipulate and control the surface properties of polymer films, without altering the substrate properties, is crucial to their wide-spread applications. In this work, a simple one-step method for the direct immobilization of benzyl chloride groups (as the effective atom transfer radical polymerization (ATRP) initiators) on the polymer films was developed via benzophenone-induced coupling of 4-vinylbenzyl chloride (VBC). Polyethylene (PE) and nylon films were selected as examples of polymer films to illustrate the functionalization of film surfaces via surface-initiated ATRP. Functional polymer brushes of (2-dimethylamino)ethyl methacrylate, sodium 4-styrenesulfonate, 2-hydroxyethyl methacrylate and glycidyl methacrylate, as well as their block copolymer brushes, have been prepared via surface-initiated ATRP from the VBC-coupled PE or nylon film surfaces. With the development of a simple approach to the covalent immobilization of ATRP initiators on polymer film surfaces and the inherent versatility of surface-initiated ATRP, the surface functionality of polymer films can be precisely tailored. - Highlights: ► Atom transfer radical polymerization initiators were simply immobilized. ► Different functional polymer brushes were readily prepared. ► Their block copolymer brushes were also readily prepared

  11. Gelatin Functionalization of Biomaterial Surfaces: Strategies for Immobilization and Visualization

    Directory of Open Access Journals (Sweden)

    Peter Dubruel

    2011-01-01

    Full Text Available In the present work, the immobilization of gelatin as biopolymer on two types of implantable biomaterials, polyimide and titanium, was compared. Both materials are known for their biocompatibility while lacking cell-interactive behavior. For both materials, a pre-functionalization step was required to enable gelatin immobilization. For the polyimide foils, a reactive succinimidyl ester was introduced first on the surface, followed by covalent grafting of gelatin. For the titanium material, methacrylate groups were first introduced on the Ti surface through a silanization reaction. The applied functionalities enabled the subsequent immobilization of methacrylamide modified gelatin. Both surface modified materials were characterized in depth using atomic force microscopy, static contact angle measurements, confocal fluorescence microscopy, attenuated total reflection infrared spectroscopy and X-ray photo-electron spectroscopy. The results indicated that the strategies elaborated for both material classes are suitable to apply stable gelatin coatings. Interestingly, depending on the material class studied, not all surface analysis techniques are applicable.

  12. Recommended values of clean metal surface work functions

    International Nuclear Information System (INIS)

    Derry, Gregory N.; Kern, Megan E.; Worth, Eli H.

    2015-01-01

    A critical review of the experimental literature for measurements of the work functions of clean metal surfaces of single-crystals is presented. The tables presented include all results found for low-index crystal faces except cases that were known to be contaminated surfaces. These results are used to construct a recommended value of the work function for each surface examined, along with an uncertainty estimate for that value. The uncertainties are based in part on the error distribution for all measured work functions in the literature, which is included here. The metals included in this review are silver (Ag), aluminum (Al), gold (Au), copper (Cu), iron (Fe), iridium (Ir), molybdenum (Mo), niobium (Nb), nickel (Ni), palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru), tantalum (Ta), and tungsten (W)

  13. Surface functionalization of polyamide fiber via dopamine polymerization

    Science.gov (United States)

    Kuang, Xiao-Hui; Guan, Jin-Ping; Tang, Ren-Cheng; Chen, Guo-Qiang

    2017-09-01

    The oxidative polymerization of dopamine for the functional surface modification of textile fibers has drawn great attention. In this work, the functionalization of polyamide fiber via dopamine polymerization was studied with the aim of the fabrication of hydrophilic and antistatic surface. The conditions of dopamine application were first discussed in the absence of specific oxidants in terms of the apparent color depth of polyamide fiber. Dopamine concentration, pH and time were found to exert great impact on color depth. The highest color depth was achieved at pH 8.5. In the process of modification, polydopamine was deposited onto the surface of polyamide fiber. The modified polyamide fiber displayed a yellowish brown color with excellent wash and light color fastness, and exhibited good hydrophilic, UV protection and antistatic effects. A disadvantage of the present approach was the slow rate of dopamine polymerization and functionalization.

  14. Meromorphic functions and cohomology on a Riemann surface

    International Nuclear Information System (INIS)

    Gomez-Mont, X.

    1989-01-01

    The objective of this set of notes is to introduce a series of concepts of Complex Analytic Geometry on a Riemann Surface. We motivate the introduction of cohomology groups through the analysis of meromorphic functions. We finish by showing that the set of infinitesimal deformations of a Riemann surface (the tangent space to Teichmueller space) may be computed as a Cohomology group. (author). 6 refs

  15. HRP's Healthcare Spin-Offs Through Computational Modeling and Simulation Practice Methodologies

    Science.gov (United States)

    Mulugeta, Lealem; Walton, Marlei; Nelson, Emily; Peng, Grace; Morrison, Tina; Erdemir, Ahmet; Myers, Jerry

    2014-01-01

    Spaceflight missions expose astronauts to novel operational and environmental conditions that pose health risks that are currently not well understood, and perhaps unanticipated. Furthermore, given the limited number of humans that have flown in long duration missions and beyond low Earth-orbit, the amount of research and clinical data necessary to predict and mitigate these health and performance risks are limited. Consequently, NASA's Human Research Program (HRP) conducts research and develops advanced methods and tools to predict, assess, and mitigate potential hazards to the health of astronauts. In this light, NASA has explored the possibility of leveraging computational modeling since the 1970s as a means to elucidate the physiologic risks of spaceflight and develop countermeasures. Since that time, substantial progress has been realized in this arena through a number of HRP funded activates such as the Digital Astronaut Project (DAP) and the Integrated Medical Model (IMM). Much of this success can be attributed to HRP's endeavor to establish rigorous verification, validation, and credibility (VV&C) processes that ensure computational models and simulations (M&S) are sufficiently credible to address issues within their intended scope. This presentation summarizes HRP's activities in credibility of modeling and simulation, in particular through its outreach to the community of modeling and simulation practitioners. METHODS: The HRP requires all M&S that can have moderate to high impact on crew health or mission success must be vetted in accordance to NASA Standard for Models and Simulations, NASA-STD-7009 (7009) [5]. As this standard mostly focuses on engineering systems, the IMM and DAP have invested substantial efforts to adapt the processes established in this standard for their application to biological M&S, which is more prevalent in human health and performance (HHP) and space biomedical research and operations [6,7]. These methods have also generated

  16. Erosion resistance of bionic functional surfaces inspired from desert scorpions.

    Science.gov (United States)

    Zhiwu, Han; Junqiu, Zhang; Chao, Ge; Li, Wen; Ren, Luquan

    2012-02-07

    In this paper, a bionic method is presented to improve the erosion resistance of machine components. Desert scorpion (Androctonus australis) is a typical animal living in sandy deserts, and may face erosive action of blowing sand at a high speed. Based on the idea of bionics and biologic experimental techniques, the mechanisms of the sand erosion resistance of desert scorpion were investigated. Results showed that the desert scorpions used special microtextures such as bumps and grooves to construct the functional surfaces to achieve the erosion resistance. In order to understand the erosion resistance mechanisms of such functional surfaces, the combination of computational and experimental research were carried out in this paper. The Computational Fluid Dynamics (CFD) method was applied to predict the erosion performance of the bionic functional surfaces. The result demonstrated that the microtextured surfaces exhibited better erosion resistance than the smooth surfaces. The further erosion tests indicated that the groove surfaces exhibited better erosion performance at 30° injection angle. In order to determine the effect of the groove dimensions on the erosion resistance, regression analysis of orthogonal multinomials was also performed under a certain erosion condition, and the regression equation between the erosion rate and groove distance, width, and height was established.

  17. Surface functionalization of aluminosilicate nanotubes with organic molecules

    Directory of Open Access Journals (Sweden)

    Wei Ma

    2012-02-01

    Full Text Available The surface functionalization of inorganic nanostructures is an effective approach for enriching the potential applications of existing nanomaterials. Inorganic nanotubes attract great research interest due to their one-dimensional structure and reactive surfaces. In this review paper, recent developments in surface functionalization of an aluminosilicate nanotube, “imogolite”, are introduced. The functionalization processes are based on the robust affinity between phosphate groups of organic molecules and the aluminol (AlOH surface of imogolite nanotubes. An aqueous modification process employing a water soluble ammonium salt of alkyl phosphate led to chemisorption of molecules on imogolite at the nanotube level. Polymer-chain-grafted imogolite nanotubes were prepared through surface-initiated polymerization. In addition, the assembly of conjugated molecules, 2-(5’’-hexyl-2,2’:5’,2’’-terthiophen-5-ylethylphosphonic acid (HT3P and 2-(5’’-hexyl-2,2’:5’,2’’-terthiophen-5-ylethylphosphonic acid 1,1-dioxide (HT3OP, on the imogolite nanotube surface was achieved by introducing a phosphonic acid group to the corresponding molecules. The optical and photophysical properties of these conjugated-molecule-decorated imogolite nanotubes were characterized. Moreover, poly(3-hexylthiophene (P3HT chains were further hybridized with HT3P modified imogolite to form a nanofiber hybrid.

  18. Work function modifications of graphite surface via oxygen plasma treatment

    Science.gov (United States)

    Duch, J.; Kubisiak, P.; Adolfsson, K. H.; Hakkarainen, M.; Golda-Cepa, M.; Kotarba, A.

    2017-10-01

    The surface modification of graphite by oxygen plasma was investigated experimentally (X-ray diffraction, nanoparticle tracking analysis, laser desorption ionization mass spectrometry, thermogravimetry, water contact angle) and by molecular modelling (Density Functional Theory). Generation of surface functional groups (mainly sbnd OHsurf) leads to substantial changes in electrodonor properties and wettability gauged by work function and water contact angle, respectively. The invoked modifications were analyzed in terms of Helmholtz model taking into account the theoretically determined surface dipole moment of graphite-OHsurf system (μ = 2.71 D) and experimentally measured work function increase (from 0.75 to 1.02 eV) to determine the sbnd OH surface coverage (from 0.70 to 1.03 × 1014 groups cm-2). Since the plasma treatment was confined to the surface, the high thermal stability of the graphite material was preserved as revealed by the thermogravimetric analysis. The obtained results provide a suitable quantitative background for tuning the key operating parameters of carbon electrodes: electronic properties, interaction with water and thermal stability.

  19. Density functional theory in surface science and heterogeneous catalysis

    DEFF Research Database (Denmark)

    Nørskov, Jens Kehlet; Scheffler, M.; Toulhoat, H.

    2006-01-01

    Solid surfaces are used extensively as catalysts throughout the chemical industry, in the energy sector, and in environmental protection. Recently, density functional theory has started providing new insight into the atomic-scale mechanisms of heterogeneous catalysis, helping to interpret the large...... amount of experimental data gathered during the last decades. This article shows how density functional theory can be used to describe the state of the surface during reactions and the rate of catalytic reactions. It will also show how we are beginning to understand the variation in catalytic activity...

  20. Overview on the Surface Functionalization Mechanism and Determination of Surface Functional Groups of Plasma Treated Carbon Nanotubes.

    Science.gov (United States)

    Saka, Cafer

    2018-01-02

    The use of carbon materials for many applications is due to the unique diversity of structures and properties ranging from chemical bonds between the carbon atoms of the materials to nanostructures, crystallite alignment, and microstructures. Carbon nanotubes and other nanoscale carbonaceous materials draw much attention due to their physical and chemical properties, such as high strength, high resistance to corrosion, electrical and thermal conductivity, stability and a qualified adsorbent. Carbon-based nanomaterials, which have a relatively large specific area and layered structure, can be used as an adsorbent for efficient removal of organic and inorganic contaminants. However, one of the biggest obstacles to the development of carbon-based nanomaterials adsorbents is insolubility and the lack of functional groups on the surface. There are several approaches to introduce functional groups on carbon nanotubes. One of these approaches, plasma applications, now has an important place in the creation of surface functional groups as a flexible, fast, and environmentally friendly method. This review focuses on recent information concerning the surface functionalization and modification of plasma treated carbon nanotube. This review considers the surface properties, advantages, and disadvantages of plasma-applied carbon nanotubes. It also examines the reaction mechanisms involved in the functional groups on the surface.

  1. Direct quantification of negatively charged functional groups on membrane surfaces

    KAUST Repository

    Tiraferri, Alberto

    2012-02-01

    Surface charge plays an important role in membrane-based separations of particulates, macromolecules, and dissolved ionic species. In this study, we present two experimental methods to determine the concentration of negatively charged functional groups at the surface of dense polymeric membranes. Both techniques consist of associating the membrane surface moieties with chemical probes, followed by quantification of the bound probes. Uranyl acetate and toluidine blue O dye, which interact with the membrane functional groups via complexation and electrostatic interaction, respectively, were used as probes. The amount of associated probes was quantified using liquid scintillation counting for uranium atoms and visible light spectroscopy for the toluidine blue dye. The techniques were validated using self-assembled monolayers of alkanethiols with known amounts of charged moieties. The surface density of negatively charged functional groups of hand-cast thin-film composite polyamide membranes, as well as commercial cellulose triacetate and polyamide membranes, was quantified under various conditions. Using both techniques, we measured a negatively charged functional group density of 20-30nm -2 for the hand-cast thin-film composite membranes. The ionization behavior of the membrane functional groups, determined from measurements with toluidine blue at varying pH, was consistent with published data for thin-film composite polyamide membranes. Similarly, the measured charge densities on commercial membranes were in general agreement with previous investigations. The relative simplicity of the two methods makes them a useful tool for quantifying the surface charge concentration of a variety of surfaces, including separation membranes. © 2011 Elsevier B.V.

  2. Binding affinity of surface functionalized gold nanoparticles to hydroxyapatite.

    Science.gov (United States)

    Ross, Ryan D; Roeder, Ryan K

    2011-10-01

    Gold nanoparticles (Au NPs) have been investigated for a number of biomedical applications, including drug and gene delivery vehicles, thermal ablation therapy, diagnostic sensors, and imaging contrast agents. Surface functionalization with molecular groups exhibiting calcium affinity can enable targeted delivery of Au NPs to calcified tissue, including damaged bone tissue. Therefore, the objective of this study was to investigate the binding affinity of functionalized Au NPs for targeted delivery to bone mineral, using hydroxyapatite (HA) crystals as a synthetic analog in vitro. Au NPs were synthesized to a mean particle size of 10-15 nm and surface functionalized with either L-glutamic acid, 2-aminoethylphosphonic acid, or alendronate, which exhibit a primary amine for binding gold opposite carboxylate, phosphonate, or bisphosphonate groups, respectively, for targeting calcium. Bisphosphonate functionalized Au NPs exhibited the most rapid binding kinetics and greatest binding affinity to HA, followed by glutamic acid and phosphonic acid. All functional groups reached complete binding after 24 h. Equilibrium binding constants in de-ionized water, determined by nonlinear regression of Langmuir isotherms, were 3.40, 0.69, and 0.25 mg/L for bisphosphonate, carboxylate, and phosphonate functionalized Au NPs, respectively. Functionalized Au NPs exhibited lower overall binding in fetal bovine serum compared to de-ionized water, but relative differences between functional groups were similar. Copyright © 2011 Wiley Periodicals, Inc.

  3. Membrane mimetic surface functionalization of nanoparticles: Methods and applications

    Science.gov (United States)

    Weingart, Jacob; Vabbilisetty, Pratima; Sun, Xue-Long

    2013-01-01

    Nanoparticles (NPs), due to their size-dependent physical and chemical properties, have shown remarkable potential for a wide range of applications over the past decades. Particularly, the biological compatibilities and functions of NPs have been extensively studied for expanding their potential in areas of biomedical application such as bioimaging, biosensing, and drug delivery. In doing so, surface functionalization of NPs by introducing synthetic ligands and/or natural biomolecules has become a critical component in regards to the overall performance of the NP system for its intended use. Among known examples of surface functionalization, the construction of an artificial cell membrane structure, based on phospholipids, has proven effective in enhancing biocompatibility and has become a viable alternative to more traditional modifications, such as direct polymer conjugation. Furthermore, certain bioactive molecules can be immobilized onto the surface of phospholipid platforms to generate displays more reminiscent of cellular surface components. Thus, NPs with membrane-mimetic displays have found use in a range of bioimaging, biosensing, and drug delivery applications. This review herein describes recent advances in the preparations and characterization of integrated functional NPs covered by artificial cell membrane structures and their use in various biomedical applications. PMID:23688632

  4. Curves and surfaces represented by polynomial support functions

    DEFF Research Database (Denmark)

    Sir, Z.; Gravesen, Jens; Juttler, B.

    2008-01-01

    This paper studies shapes (curves and surfaces) which can be described by (piecewise) polynomial support functions. The class of these shapes is closed under convolutions, offsetting, rotations and translations. We give a geometric discussion of these shapes and present methods for the approximat...

  5. Surface functionalization of HF-treated silicon nanowires

    Indian Academy of Sciences (India)

    Administrator

    well as applications. One of the special interests of SiNWs is that their surfaces can be easily modified to act as both elec- ... functionalized the SiNWs via nanoscale Joule heat- ing. 23. Shir et al investigated the oxidation of silicon nanowires. 24 .... cording to Vegard's law. 29. Figure 5b presents a TEM image of one single.

  6. Bio-inspired functional surfaces for advanced applications

    DEFF Research Database (Denmark)

    Malshe, Ajay; Rajurkar, Kamlakar; Samant, Anoop

    2013-01-01

    , are being evolved to a higher state of intelligent functionality. These surfaces became more efficient by using combinations of available materials, along with unique physical and chemical strategies. Noteworthy physical strategies include features such as texturing and structure, and chemical strategies...

  7. Scattering function for a model of interacting surfaces

    International Nuclear Information System (INIS)

    Colangelo, P.; Gonnella, G.; Maritan, A.

    1993-01-01

    The two-point correlation function of an ensemble of interacting closed self-avoiding surfaces on a cubic lattice is analyzed in the disordered phase, which corresponds to the paramagnetic region in a related spin formulation. Mean-field theory and Monte Carlo simulations predict the existence of a disorder line which corresponds to a transition from an exponential decay to an oscillatory damped behavior of the two-point correlation function. The relevance of the results for the description of amphiphilic systems in a microemulsion phase is discussed. The scattering function is also calculated for a bicontinuous phase coexisting with the paramagnetic phase

  8. Surface functionalization of detonation nanodiamonds by phosphonic dichloride derivatives.

    Science.gov (United States)

    Presti, Charlene; Alauzun, Johan G; Laurencin, Danielle; Mutin, P Hubert

    2014-08-05

    A new method for the functionalization of detonation nanodiamonds (DNDs) is proposed, on the basis of surface modification with phosphonic dichloride derivatives. DNDs were first modified by phenylphosphonic dichloride, and the grafting modes and hydrolytic stability under neutral conditions were investigated using (1)H, (13)C, and (31)P solid state NMR spectroscopy, Fourier transform infrared spectroscopy, as well as elemental analysis. Then, in order to illustrate the possibilities offered by this method, DNDs functionalized by mesityl imidazolium groups were obtained by postmodification of DNDs modified by 12-bromododecylphosphonic dichloride. The oxidative thermal stability of the functionalized DNDs was investigated using thermogravimetric analysis.

  9. Simultaneous detection of forbidden chemical residues in milk using dual-label time-resolved reverse competitive chemiluminescent immunoassay based on amine group functionalized surface.

    Directory of Open Access Journals (Sweden)

    Dongdong Zhang

    Full Text Available In this study, a sensitive dual-label time-resolved reverse competitive chemiluminescent immunoassay was developed for simultaneous detection of chloramphenicol (CAP and clenbuterol (CLE in milk. The strategy was performed based on the distinction of the kinetic characteristics of horseradish peroxidase (HRP and alkaline phosphatase (ALP in chemiluminesecence (CL systems and different orders of magnitude in HRP CL value for CAP and ALP CL value for CLE in the chemiluminescent immunoassay. Capture antibodies were covalently bound to the amine group functionalized chemiluminescent microtiter plate (MTP for efficient binding of detection antibodies for the enzymes labeled CAP (HRP-CAP and CLE (ALP-CLE. The CL signals were recorded at different time points by the automatic luminometers with significant distinction in the dynamic curves. When we considered the ALP CL value (about 10(5 of CLE as background for HRP CL signal value (about 10(7 of CAP, there was no interaction from ALP CL background of CLE and the differentiation of CAP and CLE can be easily achieved. The 50% inhibition concentration (IC50 values of CAP and CLE in milk samples were 0.00501 µg L(-1 and 0.0128 µg L(-1, with the ranges from 0.0003 µg L(-1 to 0.0912 µg L(-1 and from 0.00385 µg L(-1 to 0.125 µg L(-1, respectively. The developed method is more sensitive and of less duration than the commercial ELISA kits, suitable for simultaneous screening of CAP and CLE.

  10. Human Research Program (HRP) Exploration Medical Capability (ExMC) Standing Review Panel (SRP)

    Science.gov (United States)

    Cintron, Nitza; Dutson, Eric; Friedl, Karl; Hyman, William; Jemison, Mae; Klonoff, David

    2009-01-01

    The SRP believes strongly that regularly performed in-flight crew assessments are needed in order to identify a change in health status before a medical condition becomes clinically apparent. It is this early recognition in change that constitutes the foundation of the "occupational health model" expounded in the HRP Requirements Document as a key component of the HRP risk mitigation strategy that will enable its objective of "prevention and mitigation of human health and performance risks". A regular crew status examination of physiological and clinical performance is needed. This can be accomplished through instrumented monitoring of routine embedded tasks. The SRP recommends addition of a new gap to address this action under Category 3.0 Mitigate the Risk. This new gap is closely associated with Task 4.19 which addresses the lack of adequate biomedical monitoring capabilities for performing periodic clinical status evaluations and contingency medical monitoring. A corollary to these gaps is the critical emphasis on preventive medicine, not only during pre- and post-flight phases of a mission as is the current practice, but continued into the in-flight phases of exploration class missions.

  11. Silver nanoprisms self-assembly on differently functionalized silica surface

    International Nuclear Information System (INIS)

    Pilipavicius, J; Chodosovskaja, A; Beganskiene, A; Kareiva, A

    2015-01-01

    In this work colloidal silica/silver nanoprisms (NPRs) composite coatings were made. Firstly colloidal silica sols were synthesized by sol-gel method and produced coatings on glass by dip-coating technique. Next coatings were silanized by (3-Aminopropyl)triethoxysilane (APTES), N-[3-(Trimethoxysilyl)propyl]ethylenediamine (AEAPTMS), (3- Mercaptopropyl)trimethoxysilane (MPTMS). Silver NPRs where synthesized via seed-mediated method and high yield of 94±15 nm average edge length silver NPRs were obtained with surface plasmon resonance peak at 921 nm. Silica-Silver NPRs composite coatings obtained by selfassembly on silica coated-functionalized surface. In order to find the most appropriate silanization way for Silver NPRs self-assembly, the composite coatings were characterized by scanning electron microscopy (SEM), dynamic light scattering (DLS), water contact angle (CA) and surface free energy (SFE) methods. Results have showed that surface functionalization is necessary to achieve self-assembled Ag NPRs layer. MPTMS silanized coatings resulted sparse distribution of Ag NPRs. Most homogeneous, even distribution composite coatings obtained on APTES functionalized silica coatings, while AEAPTMS induced strong aggregation of Silver NPRs

  12. Silver nanoprisms self-assembly on differently functionalized silica surface

    Science.gov (United States)

    Pilipavicius, J.; Chodosovskaja, A.; Beganskiene, A.; Kareiva, A.

    2015-03-01

    In this work colloidal silica/silver nanoprisms (NPRs) composite coatings were made. Firstly colloidal silica sols were synthesized by sol-gel method and produced coatings on glass by dip-coating technique. Next coatings were silanized by (3-Aminopropyl)triethoxysilane (APTES), N-[3-(Trimethoxysilyl)propyl]ethylenediamine (AEAPTMS), (3- Mercaptopropyl)trimethoxysilane (MPTMS). Silver NPRs where synthesized via seed-mediated method and high yield of 94±15 nm average edge length silver NPRs were obtained with surface plasmon resonance peak at 921 nm. Silica-Silver NPRs composite coatings obtained by selfassembly on silica coated-functionalized surface. In order to find the most appropriate silanization way for Silver NPRs self-assembly, the composite coatings were characterized by scanning electron microscopy (SEM), dynamic light scattering (DLS), water contact angle (CA) and surface free energy (SFE) methods. Results have showed that surface functionalization is necessary to achieve self-assembled Ag NPRs layer. MPTMS silanized coatings resulted sparse distribution of Ag NPRs. Most homogeneous, even distribution composite coatings obtained on APTES functionalized silica coatings, while AEAPTMS induced strong aggregation of Silver NPRs.

  13. Minimal models on Riemann surfaces: The partition functions

    International Nuclear Information System (INIS)

    Foda, O.

    1990-01-01

    The Coulomb gas representation of the A n series of c=1-6/[m(m+1)], m≥3, minimal models is extended to compact Riemann surfaces of genus g>1. An integral representation of the partition functions, for any m and g is obtained as the difference of two gaussian correlation functions of a background charge, (background charge on sphere) x (1-g), and screening charges integrated over the surface. The coupling constant x (compacitification radius) 2 of the gaussian expressions are, as on the torus, m(m+1), and m/(m+1). The partition functions obtained are modular invariant, have the correct conformal anomaly and - restricting the propagation of states to a single handle - one can verify explicitly the decoupling of the null states. On the other hand, they are given in terms of coupled surface integrals, and it remains to show how they degenerate consistently to those on lower-genus surfaces. In this work, this is clear only at the lattice level, where no screening charges appear. (orig.)

  14. Minimal models on Riemann surfaces: The partition functions

    Energy Technology Data Exchange (ETDEWEB)

    Foda, O. (Katholieke Univ. Nijmegen (Netherlands). Inst. voor Theoretische Fysica)

    1990-06-04

    The Coulomb gas representation of the A{sub n} series of c=1-6/(m(m+1)), m{ge}3, minimal models is extended to compact Riemann surfaces of genus g>1. An integral representation of the partition functions, for any m and g is obtained as the difference of two gaussian correlation functions of a background charge, (background charge on sphere) x (1-g), and screening charges integrated over the surface. The coupling constant x (compacitification radius){sup 2} of the gaussian expressions are, as on the torus, m(m+1), and m/(m+1). The partition functions obtained are modular invariant, have the correct conformal anomaly and - restricting the propagation of states to a single handle - one can verify explicitly the decoupling of the null states. On the other hand, they are given in terms of coupled surface integrals, and it remains to show how they degenerate consistently to those on lower-genus surfaces. In this work, this is clear only at the lattice level, where no screening charges appear. (orig.).

  15. Surface functional groups in capacitive deionization with porous carbon electrodes

    Science.gov (United States)

    Hemmatifar, Ali; Oyarzun, Diego I.; Palko, James W.; Hawks, Steven A.; Stadermann, Michael; Santiago, Juan G.; Stanford Microfluidics Lab Team; Lawrence Livermore National Lab Team

    2017-11-01

    Capacitive deionization (CDI) is a promising technology for removal of toxic ions and salt from water. In CDI, an applied potential of about 1 V to pairs of porous electrodes (e.g. activated carbon) induces ion electromigration and electrostatic adsorption at electrode surfaces. Immobile surface functional groups play a critical role in the type and capacity of ion adsorption, and this can dramatically change desalination performance. We here use models and experiments to study weak electrolyte surface groups which protonate and/or depropotante based on their acid/base dissociation constants and local pore pH. Net chemical surface charge and differential capacitance can thus vary during CDI operation. In this work, we present a CDI model based on weak electrolyte acid/base equilibria theory. Our model incorporates preferential cation (anion) adsorption for activated carbon with acidic (basic) surface groups. We validated our model with experiments on custom built CDI cells with a variety of functionalizations. To this end, we varied electrolyte pH and measured adsorption of individual anionic and cationic ions using inductively coupled plasma mass spectrometry (ICP-MS) and ion chromatography (IC) techniques. Our model shows good agreement with experiments and provides a framework useful in the design of CDI control schemes.

  16. Usage of analytical diagnostics when evaluating functional surface material defects

    Directory of Open Access Journals (Sweden)

    R. Frischer

    2015-10-01

    Full Text Available There are occurring defects due to defects mechanisms on parts of production devices surfaces. Outer defects pronouncement is changing throw the time with unequal speed. This variability of defect’s mechanism development cause that is impossible to evaluate technical state of the device in any moment, without the necessary underlying information. Proposed model is based on analytical diagnostics basis. Stochastic model with usage of Weibull probability distribution can assign probability of function surface defect occurrence on the operational information in any moment basis. The knowledge of defect range limiting moment, then enable when and in what range will be necessary to make renewal.

  17. Plant Surfaces: Structures and Functions for Biomimetic Innovations

    Science.gov (United States)

    Barthlott, Wilhelm; Mail, Matthias; Bhushan, Bharat; Koch, Kerstin

    2017-04-01

    An overview of plant surface structures and their evolution is presented. It combines surface chemistry and architecture with their functions and refers to possible biomimetic applications. Within some 3.5 billion years biological species evolved highly complex multifunctional surfaces for interacting with their environments: some 10 million living prototypes (i.e., estimated number of existing plants and animals) for engineers. The complexity of the hierarchical structures and their functionality in biological organisms surpasses all abiotic natural surfaces: even superhydrophobicity is restricted in nature to living organisms and was probably a key evolutionary step with the invasion of terrestrial habitats some 350-450 million years ago in plants and insects. Special attention should be paid to the fact that global environmental change implies a dramatic loss of species and with it the biological role models. Plants, the dominating group of organisms on our planet, are sessile organisms with large multifunctional surfaces and thus exhibit particular intriguing features. Superhydrophilicity and superhydrophobicity are focal points in this work. We estimate that superhydrophobic plant leaves (e.g., grasses) comprise in total an area of around 250 million km2, which is about 50% of the total surface of our planet. A survey of structures and functions based on own examinations of almost 20,000 species is provided, for further references we refer to Barthlott et al. (Philos. Trans. R. Soc. A 374: 20160191, 1). A basic difference exists between aquatic non-vascular and land-living vascular plants; the latter exhibit a particular intriguing surface chemistry and architecture. The diversity of features is described in detail according to their hierarchical structural order. The first underlying and essential feature is the polymer cuticle superimposed by epicuticular wax and the curvature of single cells up to complex multicellular structures. A descriptive terminology

  18. Aryl Diazonium Chemistry for the Surface Functionalization of Glassy Biosensors

    Directory of Open Access Journals (Sweden)

    Wei Zheng

    2016-03-01

    Full Text Available Nanostring resonator and fiber-optics-based biosensors are of interest as they offer high sensitivity, real-time measurements and the ability to integrate with electronics. However, these devices are somewhat impaired by issues related to surface modification. Both nanostring resonators and photonic sensors employ glassy materials, which are incompatible with electrochemistry. A surface chemistry approach providing strong and stable adhesion to glassy surfaces is thus required. In this work, a diazonium salt induced aryl film grafting process is employed to modify a novel SiCN glassy material. Sandwich rabbit IgG binding assays are performed on the diazonium treated SiCN surfaces. Fluorescently labelled anti-rabbit IgG and anti-rabbit IgG conjugated gold nanoparticles were used as markers to demonstrate the absorption of anti-rabbit IgG and therefore verify the successful grafting of the aryl film. The results of the experiments support the effectiveness of diazonium chemistry for the surface functionalization of SiCN surfaces. This method is applicable to other types of glassy materials and potentially can be expanded to various nanomechanical and optical biosensors.

  19. Aryl Diazonium Chemistry for the Surface Functionalization of Glassy Biosensors

    Science.gov (United States)

    Zheng, Wei; van den Hurk, Remko; Cao, Yong; Du, Rongbing; Sun, Xuejun; Wang, Yiyu; McDermott, Mark T.; Evoy, Stephane

    2016-01-01

    Nanostring resonator and fiber-optics-based biosensors are of interest as they offer high sensitivity, real-time measurements and the ability to integrate with electronics. However, these devices are somewhat impaired by issues related to surface modification. Both nanostring resonators and photonic sensors employ glassy materials, which are incompatible with electrochemistry. A surface chemistry approach providing strong and stable adhesion to glassy surfaces is thus required. In this work, a diazonium salt induced aryl film grafting process is employed to modify a novel SiCN glassy material. Sandwich rabbit IgG binding assays are performed on the diazonium treated SiCN surfaces. Fluorescently labelled anti-rabbit IgG and anti-rabbit IgG conjugated gold nanoparticles were used as markers to demonstrate the absorption of anti-rabbit IgG and therefore verify the successful grafting of the aryl film. The results of the experiments support the effectiveness of diazonium chemistry for the surface functionalization of SiCN surfaces. This method is applicable to other types of glassy materials and potentially can be expanded to various nanomechanical and optical biosensors. PMID:26985910

  20. Aryl Diazonium Chemistry for the Surface Functionalization of Glassy Biosensors.

    Science.gov (United States)

    Zheng, Wei; van den Hurk, Remko; Cao, Yong; Du, Rongbing; Sun, Xuejun; Wang, Yiyu; McDermott, Mark T; Evoy, Stephane

    2016-03-14

    Nanostring resonator and fiber-optics-based biosensors are of interest as they offer high sensitivity, real-time measurements and the ability to integrate with electronics. However, these devices are somewhat impaired by issues related to surface modification. Both nanostring resonators and photonic sensors employ glassy materials, which are incompatible with electrochemistry. A surface chemistry approach providing strong and stable adhesion to glassy surfaces is thus required. In this work, a diazonium salt induced aryl film grafting process is employed to modify a novel SiCN glassy material. Sandwich rabbit IgG binding assays are performed on the diazonium treated SiCN surfaces. Fluorescently labelled anti-rabbit IgG and anti-rabbit IgG conjugated gold nanoparticles were used as markers to demonstrate the absorption of anti-rabbit IgG and therefore verify the successful grafting of the aryl film. The results of the experiments support the effectiveness of diazonium chemistry for the surface functionalization of SiCN surfaces. This method is applicable to other types of glassy materials and potentially can be expanded to various nanomechanical and optical biosensors.

  1. Nanodrop on a nanorough solid surface: Density functional theory considerations

    Science.gov (United States)

    Berim, Gersh O.; Ruckenstein, Eli

    2008-07-01

    The density distributions and contact angles of liquid nanodrops on nanorough solid surfaces are determined on the basis of a nonlocal density functional theory. Two kinds of roughness, chemical and physical, are examined. The former considers the substrate as a sequence of two kinds of semi-infinite vertical plates of equal thicknesses but of different natures with different strengths for the liquid-solid interactions. The physical roughness involves an ordered set of pillars on a flat homogeneous surface. Both hydrophobic and hydrophilic surfaces were considered. For the chemical roughness, the contact angle which the drop makes with the flat surface increases when the strength of the liquid-solid interaction for one kind of plates decreases with respect to the fixed value of the other kind of plates. Such a behavior is in agreement with the Cassie-Baxter expression derived from macroscopic considerations. For the physical roughness on a hydrophobic surface, the contact angle which a drop makes with the plane containing the tops of the pillars increases with increasing roughness. Such a behavior is consistent with the Wenzel formula developed for macroscopic drops. For hydrophilic surfaces, as the roughness increases the contact angle first increases, in contradiction with the Wenzel formula, which predicts for hydrophilic surfaces a decrease of the contact angle with increasing roughness. However, a further increase in roughness changes nonmonotonously the contact angle, and at some roughness, the drop disappears and only a liquid film is present on the surface. It was also found that the contact angle has a periodic dependence on the volume of the drop.

  2. Synthesis, characterization, and selective surface functionalization of structured nanoparticles

    OpenAIRE

    Hofmann, Andreas

    2010-01-01

    In this thesis, open questions in the field of nanomaterials are investigated and answered. These topics are focused on the study of doping agents in the crystal lattice of semiconductor nanoparticles, the use of oleic acid coated iron oxide nanoparticles for applications in biological systems, and the regioselective surface functionalization of gold nanoparticles for a controlled linkage of single particles. In order to better understand the spin properties of dopants in the core of sem...

  3. Sortase A-mediated functionalization of nanobodies toward surface coupling

    OpenAIRE

    TA, Duy Tien; STEEN REDEKER, Erik; GUEDENS, Wanda; ADRIAENSENS, Peter

    2013-01-01

    The conserved LPETG motif, at which sortase A-catalyzed transpeptidation occurs, is engineered at the C-terminal region of the variable domain of single-domain heavy chain antibody (or nanobody) against Vascular Cell Adhesion Molecule 1 (VCAM1). The recombinant nanobody can then subsequently be ligated, under sortase A catalysis, to a variety of oligoglycine containing targets, including material surfaces, contrast labeling molecules and molecules functionalized for specific chemical coupling...

  4. Functionalization of the hydroxyapatite nanoparticles surface: source of new applications

    International Nuclear Information System (INIS)

    Rojas Sanchez, Leonardo

    2012-01-01

    The surface of the nano-calcium hydroxyapatite, Ca 10 (PO 4 ) 6 (OH) 2 is reacted with stearic acid, succinic anhydride, succinimide and 2 a minoetil dihydrogenphosphate. Introduction of different functional groups is given onto the surface. An ionic interaction is identified by infrared spectroscopy and Raman between the carboxylate groups of the resulting organic molecules and calcium of the hydroxyapatite. The formation of a P-O-P pyrophosphate type bond has been for 2-aminoethyl dihydrogen phosphate with hydroxyapatite groups. Hydroxyapatite phase was remained in all cases after the reaction as demonstrated by diffraction of x-ray in powder. The amount of spiked molecules is quantified by analysis of thermal degradation which together with the determination of the surface area by BET isotherms of nitrogen adsorption. A degree of surface coverage is estimated by the organic molecules. A maximum percentage of 71% is obtained for the functionalization with succinic anhydride, followed by 57% for the reaction with stearic acid. Dilute suspensions of different materials were prepared for which in phosphate buffer solution have presented two populations around 2 and 5 μm in diameter for the modified particles. The ζ-Potential of various materials was determined occurring a variation in the potential of the unmodified hydroxyapatite. The particles with physicochemical properties different of the starting hydroxyapatite were obtained, this has expanded the range of application of the material. (author) [es

  5. Surface functionalization with strontium-containing nanocomposite coatings via EPD.

    Science.gov (United States)

    Ma, Kena; Huang, Dan; Cai, Jing; Cai, Xinjie; Gong, Lingling; Huang, Pin; Wang, Yining; Jiang, Tao

    2016-10-01

    Metal orthopedic implants still face challenges in some compromised conditions, partly due to bio-inertness. The present study aimed to functionalize metallic implants with organic-inorganic nanocomposite (strontium-containing chitosan/gelatin) coatings through a simple single-step electrophoretic deposition under mild conditions. The surface characterization and in vitro cellular response were studied and compared with chitosan/gelatin (CS/G) coatings. SEM images suggested the inorganic nanoparticles may be encapsulated within or mixed with organic polymers. The XRD patterns showed that strontium carbonate was generated in the coatings. The TEM images revealed strontium-containing nanoparticles were released from the coatings in PBS. The continuous release after the initial burst release ensured the enduring effects of the functionalized surface. The tensile bond strength of the coatings to the substrates increased after the addition of strontium. In vitro cellular study confirmed that strontium-containing coatings supported the proliferation of MC3T3-E1 cells and exhibited excellent ability to enhance the differentiation of such pre-osteoblasts. Therefore, such organic-inorganic nanocomposite coatings are a promising candidate to functionalize orthopedic implant surfaces. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Technological review of the HRP manufacturing process R and D activity

    International Nuclear Information System (INIS)

    Visca, Eliseo; Pizzuto, A.; Gavila, P.; Riccardi, B.; Roccella, S.; Candura, D.; Sanguinetti, G.P.

    2013-01-01

    Highlights: • R and D activities for the manufacturing of ITER divertor high heat flux plasma-facing components (HHFC). • ENEA and Ansaldo have jointly manufactured several actively cooled monoblock mock-ups and prototypical components. • Successful manufacturing by HRP (hot radial pressing) and PBC (pre-brazed casting) of both W and CFC armoured small and medium scale mockups. • ENEA-ANSALDO participate to the European programme for the qualification of the manufacturing technology for the ITER divertor IVT. • A qualification divertor inner vertical target prototype successfully tested at ITER relevant thermal heat fluxes. -- Abstract: ENEA and Ansaldo Nucleare S.p.A. have been deeply involved in the European International Thermonuclear Experimental Reactor (ITER) R and D activities for the manufacturing of high heat flux plasma-facing components (HHFC), and in particular for the inner vertical target (IVT) of the ITER divertor. This component has to be manufactured by using both armour and structural materials whose properties are defined by ITER. Their physical properties prevent the use of standard joining techniques. The reference armour materials are tungsten and carbon/carbon fibre composite (CFC). The cooling pipe is made of copper alloy (CuCrZr-IG). During the last years ENEA and Ansaldo have jointly manufactured several actively cooled monoblock mock-ups and prototypical components of different length, geometry and materials, by using innovative processes: HRP (hot radial pressing) and PBC (pre-brazed casting). The history of the technical issues solved during the R and D phase and the improvements implemented to the assembling tools and equipments are reviewed in the paper together with the testing results. The optimization of the processes started from the successful manufacturing of both W and CFC armoured small scale mockups thermal fatigue tested in the worst ITER operating condition (20 MW/m 2 ) through the achievement of record

  7. Technological review of the HRP manufacturing process R and D activity

    Energy Technology Data Exchange (ETDEWEB)

    Visca, Eliseo, E-mail: eliseo.visca@enea.it [Associazione EURATOM-ENEA sulla Fusione, C.R. Frascati, Via E. Fermi 45, IT-00044 Frascati (Italy); Pizzuto, A. [Associazione EURATOM-ENEA sulla Fusione, C.R. Frascati, Via E. Fermi 45, IT-00044 Frascati (Italy); Gavila, P.; Riccardi, B. [Fusion For Energy, C. Josep Pla 2, ES-08019 Barcelona (Spain); Roccella, S. [Associazione EURATOM-ENEA sulla Fusione, C.R. Frascati, Via E. Fermi 45, IT-00044 Frascati (Italy); Candura, D.; Sanguinetti, G.P. [Ansaldo Nucleare S.p.A., Corso Perrone 25, IT-16121 Genova (Italy)

    2013-10-15

    Highlights: • R and D activities for the manufacturing of ITER divertor high heat flux plasma-facing components (HHFC). • ENEA and Ansaldo have jointly manufactured several actively cooled monoblock mock-ups and prototypical components. • Successful manufacturing by HRP (hot radial pressing) and PBC (pre-brazed casting) of both W and CFC armoured small and medium scale mockups. • ENEA-ANSALDO participate to the European programme for the qualification of the manufacturing technology for the ITER divertor IVT. • A qualification divertor inner vertical target prototype successfully tested at ITER relevant thermal heat fluxes. -- Abstract: ENEA and Ansaldo Nucleare S.p.A. have been deeply involved in the European International Thermonuclear Experimental Reactor (ITER) R and D activities for the manufacturing of high heat flux plasma-facing components (HHFC), and in particular for the inner vertical target (IVT) of the ITER divertor. This component has to be manufactured by using both armour and structural materials whose properties are defined by ITER. Their physical properties prevent the use of standard joining techniques. The reference armour materials are tungsten and carbon/carbon fibre composite (CFC). The cooling pipe is made of copper alloy (CuCrZr-IG). During the last years ENEA and Ansaldo have jointly manufactured several actively cooled monoblock mock-ups and prototypical components of different length, geometry and materials, by using innovative processes: HRP (hot radial pressing) and PBC (pre-brazed casting). The history of the technical issues solved during the R and D phase and the improvements implemented to the assembling tools and equipments are reviewed in the paper together with the testing results. The optimization of the processes started from the successful manufacturing of both W and CFC armoured small scale mockups thermal fatigue tested in the worst ITER operating condition (20 MW/m{sup 2}) through the achievement of record

  8. Diagnosing severe falciparum malaria in parasitaemic African children: a prospective evaluation of plasma PfHRP2 measurement.

    Directory of Open Access Journals (Sweden)

    Ilse C E Hendriksen

    Full Text Available In African children, distinguishing severe falciparum malaria from other severe febrile illnesses with coincidental Plasmodium falciparum parasitaemia is a major challenge. P. falciparum histidine-rich protein 2 (PfHRP2 is released by mature sequestered parasites and can be used to estimate the total parasite burden. We investigated the prognostic significance of plasma PfHRP2 and used it to estimate the malaria-attributable fraction in African children diagnosed with severe malaria.Admission plasma PfHRP2 was measured prospectively in African children (from Mozambique, The Gambia, Kenya, Tanzania, Uganda, Rwanda, and the Democratic Republic of the Congo aged 1 month to 15 years with severe febrile illness and a positive P. falciparum lactate dehydrogenase (pLDH-based rapid test in a clinical trial comparing parenteral artesunate versus quinine (the AQUAMAT trial, ISRCTN 50258054. In 3,826 severely ill children, Plasmadium falciparum PfHRP2 was higher in patients with coma (p = 0.0209, acidosis (p<0.0001, and severe anaemia (p<0.0001. Admission geometric mean (95%CI plasma PfHRP2 was 1,611 (1,350-1,922 ng/mL in fatal cases (n = 381 versus 1,046 (991-1,104 ng/mL in survivors (n = 3,445, p<0.0001, without differences in parasitaemia as assessed by microscopy. There was a U-shaped association between log(10 plasma PfHRP2 and risk of death. Mortality increased 20% per log(10 increase in PfHRP2 above 174 ng/mL (adjusted odds ratio [AOR] 1.21, 95%CI 1.05-1.39, p = 0.009. A mechanistic model assuming a PfHRP2-independent risk of death in non-malaria illness closely fitted the observed data and showed malaria-attributable mortality less than 50% with plasma PfHRP2≤174 ng/mL. The odds ratio (OR for death in artesunate versus quinine-treated patients was 0.61 (95%CI 0.44-0.83, p = 0.0018 in the highest PfHRP2 tertile, whereas there was no difference in the lowest tertile (OR 1.05; 95%CI 0.69-1.61; p = 0.82. A limitation of the study is that some

  9. Filtering Non-Linear Transfer Functions on Surfaces.

    Science.gov (United States)

    Heitz, Eric; Nowrouzezahrai, Derek; Poulin, Pierre; Neyret, Fabrice

    2014-07-01

    Applying non-linear transfer functions and look-up tables to procedural functions (such as noise), surface attributes, or even surface geometry are common strategies used to enhance visual detail. Their simplicity and ability to mimic a wide range of realistic appearances have led to their adoption in many rendering problems. As with any textured or geometric detail, proper filtering is needed to reduce aliasing when viewed across a range of distances, but accurate and efficient transfer function filtering remains an open problem for several reasons: transfer functions are complex and non-linear, especially when mapped through procedural noise and/or geometry-dependent functions, and the effects of perspective and masking further complicate the filtering over a pixel's footprint. We accurately solve this problem by computing and sampling from specialized filtering distributions on the fly, yielding very fast performance. We investigate the case where the transfer function to filter is a color map applied to (macroscale) surface textures (like noise), as well as color maps applied according to (microscale) geometric details. We introduce a novel representation of a (potentially modulated) color map's distribution over pixel footprints using Gaussian statistics and, in the more complex case of high-resolution color mapped microsurface details, our filtering is view- and light-dependent, and capable of correctly handling masking and occlusion effects. Our approach can be generalized to filter other physical-based rendering quantities. We propose an application to shading with irradiance environment maps over large terrains. Our framework is also compatible with the case of transfer functions used to warp surface geometry, as long as the transformations can be represented with Gaussian statistics, leading to proper view- and light-dependent filtering results. Our results match ground truth and our solution is well suited to real-time applications, requires only a few

  10. A Conjectural Generating Function for Numbers of Curves on Surfaces

    Science.gov (United States)

    Göttsche, Lothar

    I give a conjectural generating function for the numbers of δ-nodal curves in a linear system of dimension δ on an algebraic surface. It reproduces the results of Vainsencher [V] for the case δ &\\le 6 and Kleiman-Piene [K-P] for the case δ &\\le 8. The numbers of curves are expressed in terms of five universal power series, three of which I give explicitly as quasimodular forms. This gives in particular the numbers of curves of arbitrary genus on a K3 surface and an abelian surface in terms of quasimodular forms, generalizing the formula of Yau-Zaslow for rational curves on K3 surfaces. The coefficients of the other two power series can be determined by comparing with the recursive formulas of Caporaso-Harris for the Severi degrees in 2. We verify the conjecture for genus 2 curves on an abelian surface. We also discuss a link of this problem with Hilbert schemes of points.

  11. Plasma functionalized surface of commodity polymers for dopamine detection

    Energy Technology Data Exchange (ETDEWEB)

    Fabregat, Georgina [Departament d’Enginyeria Química, E.T.S. d’Enginyeria Industrial de Barcelona, Universitat Politècnica de Catalunya, Diagonal 647, 08028, Barcelona (Spain); Center for Research in Nano-Engineering, Universitat Politècnica de Catalunya, Campus Sud, Edifici C’, C/Pasqual i Vila s/n, Barcelona, E-08028 (Spain); Osorio, Joaquin [Departament d’Enginyeria Química, E.T.S. d’Enginyeria Industrial de Barcelona, Universitat Politècnica de Catalunya, Diagonal 647, 08028, Barcelona (Spain); Castedo, Alejandra [Center for Research in Nano-Engineering, Universitat Politècnica de Catalunya, Campus Sud, Edifici C’, C/Pasqual i Vila s/n, Barcelona, E-08028 (Spain); Institut de Tècniques Energètiques, E.T.S. d’Enginyeria Industrial de Barcelona, Universitat Politècnica de Catalunya, Diagonal 647, 08028, Barcelona (Spain); Armelin, Elaine [Departament d’Enginyeria Química, E.T.S. d’Enginyeria Industrial de Barcelona, Universitat Politècnica de Catalunya, Diagonal 647, 08028, Barcelona (Spain); Center for Research in Nano-Engineering, Universitat Politècnica de Catalunya, Campus Sud, Edifici C’, C/Pasqual i Vila s/n, Barcelona, E-08028 (Spain); and others

    2017-03-31

    Highlights: • Electrochemically inert polymers become electroactive after plasma functionalization. • Selective dopamine detection has been achieved functionalizing polymers with plasma. • Plasma-functionalized polymers are sensitive dopamine detectors. • XPS analyses reflect the transformation of inert polymers into electrosensors. - Abstract: We have fabricated potentially generalizable sensors based on polymeric-modified electrodes for the electrochemical detection of dopamine. Sensitive and selective sensors have been successfully obtained by applying a cold-plasma treatment during 1–2 min not only to conducting polymers but also to electrochemically inert polymers, such as polyethylene, polypropylene, polyvinylpyrrolidone, polycaprolactone and polystyrene. The effects of the plasma in the electrode surface activation, which is an essential requirement for the dopamine detection when inert polymers are used, have been investigated using X-ray photoelectron spectroscopy. Results indicate that exposure of polymer-modified electrodes to cold-plasma produces the formation of a large variety of reactive species adsorbed on the electrode surface, which catalyse the dopamine oxidation. With this technology, which is based on the application of a very simple physical functionalization, we have defined a paradox-based paradigm for the fabrication of electrochemical sensors by using inert and cheap plastics.

  12. Orthogonal chemical functionalization of patterned gold on silica surfaces.

    Science.gov (United States)

    Palazon, Francisco; Léonard, Didier; Le Mogne, Thierry; Zuttion, Francesca; Chevalier, Céline; Phaner-Goutorbe, Magali; Souteyrand, Éliane; Chevolot, Yann; Cloarec, Jean-Pierre

    2015-01-01

    Single-step orthogonal chemical functionalization procedures have been developed with patterned gold on silica surfaces. Different combinations of a silane and a thiol were simultaneously deposited on a gold/silica heterogeneous substrate. The orthogonality of the functionalization (i.e., selective grafting of the thiol on the gold areas and the silane on the silica) was demonstrated by X-ray photoelectron spectroscopy (XPS) as well as time-of-flight secondary ion mass spectrometry (ToF-SIMS) mapping. The orthogonal functionalization was used to immobilize proteins onto gold nanostructures on a silica substrate, as demonstrated by atomic force microscopy (AFM). These results are especially promising in the development of future biosensors where the selective anchoring of target molecules onto nanostructured transducers (e.g., nanoplasmonic biosensors) is a major challenge.

  13. Orthogonal chemical functionalization of patterned gold on silica surfaces

    Directory of Open Access Journals (Sweden)

    Francisco Palazon

    2015-12-01

    Full Text Available Single-step orthogonal chemical functionalization procedures have been developed with patterned gold on silica surfaces. Different combinations of a silane and a thiol were simultaneously deposited on a gold/silica heterogeneous substrate. The orthogonality of the functionalization (i.e., selective grafting of the thiol on the gold areas and the silane on the silica was demonstrated by X-ray photoelectron spectroscopy (XPS as well as time-of-flight secondary ion mass spectrometry (ToF–SIMS mapping. The orthogonal functionalization was used to immobilize proteins onto gold nanostructures on a silica substrate, as demonstrated by atomic force microscopy (AFM. These results are especially promising in the development of future biosensors where the selective anchoring of target molecules onto nanostructured transducers (e.g., nanoplasmonic biosensors is a major challenge.

  14. Analysis III analytic and differential functions, manifolds and Riemann surfaces

    CERN Document Server

    Godement, Roger

    2015-01-01

    Volume III sets out classical Cauchy theory. It is much more geared towards its innumerable applications than towards a more or less complete theory of analytic functions. Cauchy-type curvilinear integrals are then shown to generalize to any number of real variables (differential forms, Stokes-type formulas). The fundamentals of the theory of manifolds are then presented, mainly to provide the reader with a "canonical'' language and with some important theorems (change of variables in integration, differential equations). A final chapter shows how these theorems can be used to construct the compact Riemann surface of an algebraic function, a subject that is rarely addressed in the general literature though it only requires elementary techniques. Besides the Lebesgue integral, Volume IV will set out a piece of specialized mathematics towards which the entire content of the previous volumes will converge: Jacobi, Riemann, Dedekind series and infinite products, elliptic functions, classical theory of modular fun...

  15. Functionalization of silicon nanowire surfaces with metal-organic frameworks

    KAUST Repository

    Liu, Nian

    2011-12-28

    Metal-organic frameworks (MOFs) and silicon nanowires (SiNWs) have been extensively studied due to their unique properties; MOFs have high porosity and specific surface area with well-defined nanoporous structure, while SiNWs have valuable one-dimensional electronic properties. Integration of the two materials into one composite could synergistically combine the advantages of both materials and lead to new applications. We report the first example of a MOF synthesized on surface-modified SiNWs. The synthesis of polycrystalline MOF-199 (also known as HKUST-1) on SiNWs was performed at room temperature using a step-by-step (SBS) approach, and X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy dispersive spectroscopy elemental mapping were used to characterize the material. Matching of the SiNW surface functional groups with the MOF organic linker coordinating groups was found to be critical for the growth. Additionally, the MOF morphology can by tuned by changing the soaking time, synthesis temperature and precursor solution concentration. This SiNW/MOF hybrid structure opens new avenues for rational design of materials with novel functionalities. © 2011 Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

  16. Phosphatidylcholine synthesis is essential for HrpZ harpin secretion in plant pathogenic Pseudomonas syringae and non-pathogenic Pseudomonas sp. 593.

    Science.gov (United States)

    Xiong, Min; Long, Deliang; He, Huoguang; Li, Yang; Li, Yadong; Wang, Xingguo

    2014-01-01

    Pseudomonas syringae pv. syringae van Hall is important phytopathogenic bacterium of stone fruit trees, and able to elicit hypersensitive response (HR) in nonhost plants. The HrpZ, secreted via type III secretion system (T3SS) to the extracellular space of the plant, is a T3SS-dependent protein and a sole T3SS effector able to induce the host defense response outside host cells. We deleted the phosphatidylcholine synthase gene (pcs) of P. syringae pv. syringae van Hall CFCC 1336, and found that the 1336 pcs(-) mutant was unable to synthesize phosphatidylcholine and elicit a typical HR in soybean. Further studies showed that the 1336 pcs(-) mutant was unable to secrete HrpZ harpin but could express HrpZ protein in cytoplasm as effectively as the wild type. To confirm if phosphatidylcholine affects HrpZ harpin secretion, we introduced the hrpZ gene into the soil-dwelling bacterium Pseudomonas sp. 593 and the 593 pcs(-) mutant, which were unable to express HrpZ harpin and elicit HR in tobacco or soybean. Western blotting and HR assay showed that the 593H not only secreted HrpZ harpin but also caused a strong HR in tobacco and soybean. In contrast, the 593 pcs(-)H only expressed HrpZ protein in its cytoplasm at the wild type level, but did not secrete HrpZ harpin or elicit HR reaction. Our results demonstrate that phosphatidylcholine is essential for the secretion of HrpZ harpin in P. syringae pv. syringae van Hall and other Pseudomonas strains. Copyright © 2013 Elsevier GmbH. All rights reserved.

  17. Nanosensors based on functionalized nanoparticles and surface enhanced raman scattering

    Science.gov (United States)

    Talley, Chad E.; Huser, Thomas R.; Hollars, Christopher W.; Lane, Stephen M.; Satcher, Jr., Joe H.; Hart, Bradley R.; Laurence, Ted A.

    2007-11-27

    Surface-Enhanced Raman Spectroscopy (SERS) is a vibrational spectroscopic technique that utilizes metal surfaces to provide enhanced signals of several orders of magnitude. When molecules of interest are attached to designed metal nanoparticles, a SERS signal is attainable with single molecule detection limits. This provides an ultrasensitive means of detecting the presence of molecules. By using selective chemistries, metal nanoparticles can be functionalized to provide a unique signal upon analyte binding. Moreover, by using measurement techniques, such as, ratiometric received SERS spectra, such metal nanoparticles can be used to monitor dynamic processes in addition to static binding events. Accordingly, such nanoparticles can be used as nanosensors for a wide range of chemicals in fluid, gaseous and solid form, environmental sensors for pH, ion concentration, temperature, etc., and biological sensors for proteins, DNA, RNA, etc.

  18. Bionanohybrid based on bioplastic and surface-functionalized carbon nanotubes.

    Science.gov (United States)

    Singh, Ravina; Ray, Suprakas Sinha

    2010-12-01

    A bionanohybrid consisting of biodegradable/biocompatible poly(butylene succinate) (PBS) and surface-oxidized carbon nanotubes (o-CNTs) was prepared via melt-mixing method. The inherent properties of PBS were concurrently improved by the incorporation of a small amount of o-CNTs. For example, at room temperature, elongation at break increased from approximately 21.2% for pure PBS to approximately 55.1% for the nanohybrid and an increase of about approximately 150% in the value of toughness with moderate improvement in tensile modulus and strength. The dynamic mechanical properties of PBS also increased significantly after nanocomposite formation with o-CNTs. Electron microscopy and Raman spectroscopy were used to investigate the mechanical properties and improvement mechanism of surface-functionalized o-CNTs containing PBS nanohybrid.

  19. Toward spatial control of gold nanorod surface functionalization

    Science.gov (United States)

    Eller, Jonathan R.

    Gold nanorods (GNRs) show much promise for applications in biological, optoelectronic and energy applications. The resonant generation of a localized surface plasmon resonance (LSPR) at the GNR surface results in interesting optical properties and unique interactions with molecules. Combined with their biocompatibility, ease of synthesis and facile surface functionalization, these anisotropic metal particles are excellent scaffolds for the study of the interactions between nanoscale surfaces and their chemical/biological environments. Regardless of the application, however, GNR utility will not be fully realized until the chemical nature of the surface is understood and controlled. GNRs can enhance various photophysical properties of molecules. In the case of two-photon absorption (TPA), cross-section enhancements have been shown to increase with strong distance-dependence. Here, a dual approach for the conjugation of a TPA chromophore to GNRs is presented, relying on layer-by- layer (LbL) polymer wrapping and direct thiol coating of the same parent chromophore structure. Together, these approaches allow for estimated chromophore-particle distances from products in the synthesis of site- selective silica-coated GNRs is demonstrated, and the thickness tunability of the resulting core-shell materials is investigated. The redox state of methoxy- terminated poly(ethylene glycol) thiol attached to GNRs is shown to be relevant in guiding the deposition of silica, providing an important insight into the design of anisotropic composite nanomaterials. Surface-initiated Atom transfer radical polymerization (SI-ATRP) is a popular method for grafting polymers from a surface. We demonstrate our ability to grow poly(N-isopropylacrylamide) (PNIPAM) shells on the GNR surface, toward a "smart" thermoresponsive polymer shell. The role of ligand choice, molar ratio of monomer to initiator and polymerization on presence and control of shell thickness are investigated. The introduction

  20. Swarm formation control utilizing elliptical surfaces and limiting functions.

    Science.gov (United States)

    Barnes, Laura E; Fields, Mary Anne; Valavanis, Kimon P

    2009-12-01

    In this paper, we present a strategy for organizing swarms of unmanned vehicles into a formation by utilizing artificial potential fields that were generated from normal and sigmoid functions. These functions construct the surface on which swarm members travel, controlling the overall swarm geometry and the individual member spacing. Nonlinear limiting functions are defined to provide tighter swarm control by modifying and adjusting a set of control variables that force the swarm to behave according to set constraints, formation, and member spacing. The artificial potential functions and limiting functions are combined to control swarm formation, orientation, and swarm movement as a whole. Parameters are chosen based on desired formation and user-defined constraints. This approach is computationally efficient and scales well to different swarm sizes, to heterogeneous systems, and to both centralized and decentralized swarm models. Simulation results are presented for a swarm of 10 and 40 robots that follow circle, ellipse, and wedge formations. Experimental results are included to demonstrate the applicability of the approach on a swarm of four custom-built unmanned ground vehicles (UGVs).

  1. Holographic partition functions and phases for higher genus Riemann surfaces

    International Nuclear Information System (INIS)

    Maxfield, Henry; Ross, Simon F; Way, Benson

    2016-01-01

    We describe a numerical method to compute the action of Euclidean saddle points for the partition function of a two-dimensional holographic CFT on a Riemann surface of arbitrary genus, with constant curvature metric. We explicitly evaluate the action for the saddles for genus two and map out the phase structure of dominant bulk saddles in a two-dimensional subspace of the moduli space. We discuss spontaneous breaking of discrete symmetries, and show that the handlebody bulk saddles always dominate over certain non-handlebody solutions. (paper)

  2. Symposium Supramolecular Assemblies on Surface: Nanopatterning, Functionality and Reactivity

    Science.gov (United States)

    2016-05-19

    modules, steer their organisational and dynamic behaviour , and afford novel functions using well-defined homogenous surfaces, textured and sp2...three electron oxidations of singleIndiana University 11:00 AM 11:30 AM Frida 30 Beton, Peter Supramolecular  organisation  on layered semiconductors and...change in oxidation state of the metal. See J. Am. Chem. Soc. 136, 9862 (2014). 1841 - Supramolecular organisation on layered semiconductors and

  3. Fabrication of Bioactive Surfaces by Functionalization of Electroactive and Surface-Active Block Copolymers

    Directory of Open Access Journals (Sweden)

    Omotunde Olubi

    2014-08-01

    Full Text Available Biofunctional block copolymers are becoming increasingly attractive materials as active components in biosensors and other nanoscale electronic devices. We have described two different classes of block copolymers with biofuctional properties. Biofunctionality for block copolymers is achieved through functionalization with appropriate biospecific ligands. We have synthesized block copolymers of electroactive poly(3-decylthiophene and 2-hydroxyethyl methacrylate by atom transfer radical polymerization. The block copolymers were functionalized with the dinitrophenyl (DNP groups, which are capable of binding to Immunoglobulin E (IgE on cell surfaces. The block copolymers were shown to be redox active. Additionally, the triblock copolymer of α, ω-bi-biotin (poly(ethylene oxide-b-poly (styrene-b-poly(ethylene oxide was also synthesized to study their capacity to bind fluorescently tagged avidin. The surface-active property of the poly(ethylene oxide block improved the availability of the biotin functional groups on the polymer surfaces. Fluorescence microscopy observations confirm the specific binding of biotin with avidin.

  4. Analysis and design of functional micro/nano structured surfaces

    Science.gov (United States)

    Xu, Zhenzhen; Kong, Lingbao; Xu, Min

    2016-03-01

    In recent years, more and more attention has been paid to the bionic structure and functional materials. The theoretical research and fabricating ways of the Super-hydrophobic surface have sound achievements. However, the existing methods largely depend on the precision of the equipment and complex chemical substances, and it is hard to ensure the consistence of the material surface. Therefore, construction of microstructure on the surface of the material by using the method of mechanical processing to make the scale of the Super-hydrophobic surface to promote the popularization and application of Super-hydrophobic surface is of great significance. In order to put forward the innovative microstructure and to provide theoretical basis for the subsequent mechanical processing, based on the analysis of the classical theory of Super-hydrophobic, the super-hydrophobic film was by sol gel method. To explore the effects of different ratio of materials on the hydrophobicity, a micro/nano-structured super-hydrophobic coating was obtained by coating a film improved by hexamethyldisilazane (HMDS) after a film improved by polyethylene glycol (PEG) was coated. The microstructure of bilayer films is analyzed, and the double-layer film structure is simplified to design two kinds of microstructure models. For the design of the two models based on the Wenzel and Cassie equations, a roughness factor is adopted to establish the quantitative relationship between the contact angle and the microstructure parameters, and the microstructure parameters is also analyzed by using MATLAB software, and hence the optimized microstructure parameters is obtained.

  5. Frog tongue surface microstructures: functional and evolutionary patterns

    Science.gov (United States)

    Gorb, Stanislav N

    2016-01-01

    Summary Frogs (Lissamphibia: Anura) use adhesive tongues to capture fast moving, elusive prey. For this, the tongues are moved quickly and adhere instantaneously to various prey surfaces. Recently, the functional morphology of frog tongues was discussed in context of their adhesive performance. It was suggested that the interaction between the tongue surface and the mucus coating is important for generating strong pull-off forces. However, despite the general notions about its importance for a successful contact with the prey, little is known about the surface structure of frog tongues. Previous studies focused almost exclusively on species within the Ranidae and Bufonidae, neglecting the wide diversity of frogs. Here we examined the tongue surface in nine different frog species, comprising eight different taxa, i.e., the Alytidae, Bombinatoridae, Megophryidae, Hylidae, Ceratophryidae, Ranidae, Bufonidae, and Dendrobatidae. In all species examined herein, we found fungiform and filiform papillae on the tongue surface. Further, we observed a high degree of variation among tongues in different frogs. These differences can be seen in the size and shape of the papillae, in the fine-structures on the papillae, as well as in the three-dimensional organization of subsurface tissues. Notably, the fine-structures on the filiform papillae in frogs comprise hair-like protrusions (Megophryidae and Ranidae), microridges (Bufonidae and Dendrobatidae), or can be irregularly shaped or absent as observed in the remaining taxa examined herein. Some of this variation might be related to different degrees of adhesive performance and may point to differences in the spectra of prey items between frog taxa. PMID:27547606

  6. Bovine serum albumin adsorption on functionalized porous silicon surfaces

    Science.gov (United States)

    Tay, Li-Lin; Rowell, Nelson L.; Lockwood, David J.; Boukherroub, Rabah

    2004-10-01

    The large surface area within porous Si (pSi) and its strong room temperature photoluminescence (PL) make it an ideal host for biological sensors. In particular, the development of pSi-based optical sensors for DNA, enzyme and other biochemical molecules have become of great interest. Here, we demonstrate that the in-situ monitoring of the pSi PL behaviour can be used as a positive identification of bovine serum albumin (BSA) protein adsorption inside the porous matrix. Electrochemically prepared pSi films were first functionalized with undecylenic acid to produce an organic monolayer covalently attached to the porous silicon surfaces. The acid terminal group also provided favourable BSA binding sites on the pSi matrix sidewalls. In-situ PL spectra showed a gradual red shift (up to 12 meV) in the PL peak energy due to the protein incorporation into the porous matrix. The PL then exhibited a continuous blue shift after saturation of the protein molecules in the pores. This blue shift of the PL peak frequency and a steady increase in the PL intensity is evidence of surface oxidation. Comparing the specular reflectance obtained by Fourier transform infrared spectroscopy (FTIR) before and after BSA incubation confirmed the adsorption of protein in the pSi matrix.

  7. Postural Stability Margins as a Function of Support Surface Slopes.

    Directory of Open Access Journals (Sweden)

    Aviroop Dutt-Mazumder

    Full Text Available This investigation examined the effects of slope of the surface of support (35°, 30°, 20°, 10° Facing(Toe Down, 0° Flat and 10°, 20°, 25° Facing (Toe Up and postural orientation on the margins of postural stability in quiet standing of young adults. The findings showed that the center of pressure-CoP (displacement, area and length had least motion at the baseline (0° Flat platform condition that progressively increased as a function of platform angle in both facing up and down directions. The virtual time to collision (VTC dynamics revealed that the spatio-temporal margins to the functional stability boundary were progressively smaller and the VTC time series also more regular (SampEn-Sample Entropy as slope angle increased. Surface slope induces a restricted stability region with lower dimension VTC dynamics that is more constrained when postural orientation is facing down the slope. These findings provide further evidence that VTC acts as a control variable in standing posture that is influenced by the emergent dynamics of the individual-environment-task interaction.

  8. Surface Functionalization of Orthopedic Titanium Implants with Bone Sialoprotein.

    Directory of Open Access Journals (Sweden)

    Andreas Baranowski

    Full Text Available Orthopedic implant failure due to aseptic loosening and mechanical instability remains a major problem in total joint replacement. Improving osseointegration at the bone-implant interface may reduce micromotion and loosening. Bone sialoprotein (BSP has been shown to enhance bone formation when coated onto titanium femoral implants and in rat calvarial defect models. However, the most appropriate method of BSP coating, the necessary level of BSP coating, and the effect of BSP coating on cell behavior remain largely unknown. In this study, BSP was covalently coupled to titanium surfaces via an aminosilane linker (APTES, and its properties were compared to BSP applied to titanium via physisorption and untreated titanium. Cell functions were examined using primary human osteoblasts (hOBs and L929 mouse fibroblasts. Gene expression of specific bone turnover markers at the RNA level was detected at different intervals. Cell adhesion to titanium surfaces treated with BSP via physisorption was not significantly different from that of untreated titanium at any time point, whereas BSP application via covalent coupling caused reduced cell adhesion during the first few hours in culture. Cell migration was increased on titanium disks that were treated with higher concentrations of BSP solution, independent of the coating method. During the early phases of hOB proliferation, a suppressive effect of BSP was observed independent of its concentration, particularly when BSP was applied to the titanium surface via physisorption. Although alkaline phosphatase activity was reduced in the BSP-coated titanium groups after 4 days in culture, increased calcium deposition was observed after 21 days. In particular, the gene expression level of RUNX2 was upregulated by BSP. The increase in calcium deposition and the stimulation of cell differentiation induced by BSP highlight its potential as a surface modifier that could enhance the osseointegration of orthopedic implants

  9. Multiply Surface-Functionalized Nanoporous Carbon for Vehicular Hydrogen Storage

    Energy Technology Data Exchange (ETDEWEB)

    Pfeifer, Peter [Univ. of Missouri, Columbia, MO (United States). Dept. of Physics; Gillespie, Andrew [Univ. of Missouri, Columbia, MO (United States). Dept. of Physics; Stalla, David [Univ. of Missouri, Columbia, MO (United States). Dept. of Physics; Dohnke, Elmar [Univ. of Missouri, Columbia, MO (United States). Dept. of Physics

    2017-02-20

    The purpose of the project “Multiply Surface-Functionalized Nanoporous Carbon for Vehicular Hydrogen Storage” is the development of materials that store hydrogen (H2) by adsorption in quantities and at conditions that outperform current compressed-gas H2 storage systems for electric power generation from hydrogen fuel cells (HFCs). Prominent areas of interest for HFCs are light-duty vehicles (“hydrogen cars”) and replacement of batteries with HFC systems in a wide spectrum of applications, ranging from forklifts to unmanned areal vehicles to portable power sources. State-of-the-art compressed H2 tanks operate at pressures between 350 and 700 bar at ambient temperature and store 3-4 percent of H2 by weight (wt%) and less than 25 grams of H2 per liter (g/L) of tank volume. Thus, the purpose of the project is to engineer adsorbents that achieve storage capacities better than compressed H2 at pressures less than 350 bar. Adsorption holds H2 molecules as a high-density film on the surface of a solid at low pressure, by virtue of attractive surface-gas interactions. At a given pressure, the density of the adsorbed film is the higher the stronger the binding of the molecules to the surface is (high binding energies). Thus, critical for high storage capacities are high surface areas, high binding energies, and low void fractions (high void fractions, such as in interstitial space between adsorbent particles, “waste” storage volume by holding hydrogen as non-adsorbed gas). Coexistence of high surface area and low void fraction makes the ideal adsorbent a nanoporous monolith, with pores wide enough to hold high-density hydrogen films, narrow enough to minimize storage as non-adsorbed gas, and thin walls between pores to minimize the volume occupied by solid instead of hydrogen. A monolith can be machined to fit into a rectangular tank (low pressure, conformable tank), cylindrical tank

  10. Improving the Performance of Semiconductor Sensor Devices Using Surface Functionalization

    Science.gov (United States)

    Rohrbaugh, Nathaniel W.

    As production and understanding of III-nitride growth has progressed, this class of material has been used for its semiconducting properties in the fields of computer processing, microelectronics, and LEDs. As understanding of materials properties has advanced, devices were fabricated to be sensitive to environmental surroundings such as pH, gas, or ionic concentration. Simultaneously the world of pharmaceuticals and environmental science has come to the age where the use of wearable devices and active environmental sensing can not only help us learn more about our surroundings, but help save lives. At the crossroads of these two fields work has been done in marrying the high stability and electrical properties of the III-nitrides with the needs of a growing sensor field for various environments and stimuli. Device architecture can only get one so far, and thus the need for well understood surface functionalization techniques has arisen in the field of III-nitride environmental sensing. Many existing schemes for functionalization involve chemistries that may be unfriendly to a biological environment, unstable in solution, or expensive to produce. One possible solution to these issues is the work presented here, which highlights a surface modification scheme utilizing phosphonic acid based chemistry and biomolecular attachment. This dissertation presents a set of studies and experiments quantifying and analyzing the response behaviors of AlGaN/GaN field effect transistor (FET) devices via their interfacial electronic properties. Additional investigation was done on the modification of these surfaces, effects of stressful environmental conditions, and the utility of the phosphonic acid surface treatments. Signals of AlGaN/GaN FETs were measured as IDrain values and in the earliest study an average signal increase of 96.43% was observed when surfaces were incubated in a solution of a known recognition peptide sequence (SVSVGMKPSPRP). This work showed that even without

  11. A photometric function of planetary surfaces for gourmets

    Science.gov (United States)

    Shkuratov, Yuriy; Korokhin, Viktor; Shevchenko, Vasilij; Mikhalchenko, Olga; Belskaya, Irina; Kaydash, Vadym; Videen, Gorden; Zubko, Evgenij; Velikodsky, Yuriy

    2018-03-01

    A new photometric model with small number of parameters is presented. The model is based on an assumption that there exist such surfaces for which spatial brightness variations caused by small topography undulations can be reproduced exactly by corresponding spatial variations of albedo. This indistinguishability results in a differential equation suggesting a new photometric function that generalizes, in particular, the Akimov disk-function. Our model provides excellent fits in a wide phase-angle range for integral observations of asteroids of different albedos. We also carried out fitting to integral observations of the Moon and Mercury, confirming difficulties in describing Mercury's phase function at large phase angles, which were also found for the Hapke model. Comparisons of global latitude and longitude trends with our model calculations have shown good coincidence for the Moon. To retrieve the lunar trends, we use the phase-ratio technique, applying it to our telescope observations. Mapping the model parameters using LROC WAC data were carried out for a region comprising the Reiner Gamma formation. This mapping allows us to calculate phase-ratio images of the region, showing at large phase angles systematically steeper phase curves of young craters and smaller steepness for the very Reiner Gamma formation.

  12. Functionalized Surface Geometries Induce: “Bone: Formation by Autoinduction”

    Directory of Open Access Journals (Sweden)

    Ugo Ripamonti

    2018-02-01

    Full Text Available The induction of tissue formation, and the allied disciplines of tissue engineering and regenerative medicine, have flooded the twenty-first century tissue biology scenario and morphed into high expectations of a fulfilling regenerative dream of molecularly generated tissues and organs in assembling human tissue factories. The grand conceptualization of deploying soluble molecular signals, first defined by Turing as forms generating substances, or morphogens, stemmed from classic last century studies that hypothesized the presence of morphogens in several mineralized and non-mineralized mammalian matrices. The realization of morphogens within mammalian matrices devised dissociative extractions and chromatographic procedures to isolate, purify, and finally reconstitute the cloned morphogens, found to be members of the transforming growth factor-β (TGF-β supergene family, with insoluble signals or substrata to induce de novo tissue induction and morphogenesis. Can we however construct macroporous bioreactors per se capable of inducing bone formation even without the exogenous applications of the osteogenic soluble molecular signals of the TGF-β supergene family? This review describes original research on coral-derived calcium phosphate-based macroporous constructs showing that the formation of bone is independent of the exogenous application of the osteogenic soluble signals of the TGF-β supergene family. Such signals are the molecular bases of the induction of bone formation. The aim of this review is to primarily describe today's hottest topic of biomaterials' science, i.e., to construct and define osteogenetic biomaterials' surfaces that per se, in its own right, do initiate the induction of bone formation. Biomaterials are often used to reconstruct osseous defects particularly in the craniofacial skeleton. Edentulism did spring titanium implants as tooth replacement strategies. No were else that titanium surfaces require functionalized

  13. Zinc surface complexes on birnessite: A density functional theory study

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Kideok D.; Refson, Keith; Sposito, Garrison

    2009-01-05

    Biogeochemical cycling of zinc is strongly influenced by sorption on birnessite minerals (layer-type MnO2), which are found in diverse terrestrial and aquatic environments. Zinc has been observed to form both tetrahedral (Zn{sup IV}) and octahedral (Zn{sup VI}) triple-corner-sharing surface complexes (TCS) at Mn(IV) vacancy sites in hexagonal birnessite. The octahedral complex is expected to be similar to that of Zn in the Mn oxide mineral, chalcophanite (ZnMn{sub 3}O{sub 7} {center_dot} 3H{sub 2}O), but the reason for the occurrence of the four-coordinate Zn surface species remains unclear. We address this issue computationally using spin-polarized Density Functional Theory (DFT) to examine the Zn{sub IV}-TCS and Zn{sup VI}-TCS species. Structural parameters obtained by DFT geometry optimization were in excellent agreement with available experimental data on Zn-birnessites. Total energy, magnetic moments, and electron-overlap populations obtained by DFT for isolated Zn{sup IV}-TCS revealed that this species is stable in birnessite without a need for Mn(III) substitution in the octahedral sheet and that it is more effective in reducing undersaturation of surface O at a Mn vacancy than is Zn{sub VI}-TCS. Comparison between geometry-optimized ZnMn{sub 3}O{sub 7} {center_dot} 3H{sub 2}O (chalcophanite) and the hypothetical monohydrate mineral, ZnMn{sub 3}O{sub 7} {center_dot} H{sub 2}O, which contains only tetrahedral Zn, showed that the hydration state of Zn significantly affects birnessite structural stability. Finally, our study also revealed that, relative to their positions in an ideal vacancy-free MnO{sub 2}, Mn nearest to Zn in a TCS surface complex move toward the vacancy by 0.08-0.11 {angstrom}, while surface O bordering the vacancy move away from it by 0.16-0.21 {angstrom}, in agreement with recent X-ray absorption spectroscopic analyses.

  14. Comparison of the performance of the borax buffer-based HRP-enhanced reagent and the 'Lumi-Phos 530' chemiluminescence systems in the detection of biotinylated DNA.

    Science.gov (United States)

    Cercek, B; Roby, K; Siaw, M

    1995-01-01

    A comparison of two chemiluminescence methods, the borax buffer-based HRP-enhanced reagent and Lumi-Phos 530, applied to the detection of a biotinylated 30-mer DNA slot blotted onto a nylon membrane, is presented. A streptavidin-HRP and streptavidin-ALP mediated detection system was used. The HRP-enhanced system is up to 15-fold greater with respect to the signal/background ratios than the Lumi-Phos 530 system at 0.5 microgram biotinylated DNA with at least a two-fold improvement in detection sensitivity for 0.5 ng biotinylated DNA.

  15. Characterization of Sea Lettuce Surface Functional Groups by Potentiometric Titrations

    Science.gov (United States)

    Ebling, A. M.; Schijf, J.

    2008-12-01

    In pursuit of our ultimate goal to better understand the prodigious capacity of the marine macroalga Ulva lactuca (sea lettuce) for adsorbing a broad range of dissolved trace metals from seawater, we performed an initial characterization of its surface functional groups. Specifically, the number of distinct functional groups as well as their individual bulk concentrations and acid dissociation constants (pKas) were determined by potentiometric titrations in NaCl solutions of various ionic strengths (I = 0.01-5.0 M), under inert nitrogen atmosphere at 25°C. Depending on the ionic strength, Ulva samples were manually titrated down to pH 2 or 3 with 1 N HCl and then up to pH 10 with 1 N NaOH in steps of 0.1-0.2 units, continuously monitoring pH with a glass combination electrode. Titrations of a dehydrated Ulva standard reference material (BCR-279) were compared with fresh Ulva tissue cultured in our laboratory. A titration in filtered natural seawater was also compared with one in an NaCl solution of equal ionic strength. Equilibrium constants for the ionization of water in NaCl solutions as a function of ionic strength were obtained from the literature. Fits to the titration data ([H]T vs. pH) were performed with the FITEQL4.0 computer code using non-electrostatic 3-, 4-, and 5-site models, either by fixing ionic strength at its experimental value or by allowing it to be extrapolated to zero, while considering all functional group pKas and bulk concentrations as adjustable parameters. Since pKas and bulk concentrations were found to be strongly correlated, the latter were also fixed in some cases to further constrain the pKas. Whereas these calculations are currently ongoing, preliminary results point to three, possibly four, functional groups with pKas of about 4.1, 6.3, and 9.5 at I = 0. Bulk concentrations of the three groups are very similar, about 5-6×10-4 mol/g based on dry weight, which suggests that all are homogeneously distributed over the surface and

  16. Interaction between Palladium Nanoparticles and Surface-Modified Carbon Nanotubes: Role of Surface Functionalities

    DEFF Research Database (Denmark)

    Zhang, Bingsen; Shao, Lidong; Zhang, Wei

    2014-01-01

    degrees C. We focus on probing the effects of oxygen and nitrogen-containing functional groups on supported palladium nanoparticles (NPs) in the model catalytic system. The stability of palladium NPs supported on CNTs depends strongly on the surface properties of CNTs. Moreover, the oxygen...... feature, instability, and subtle response of the components upon application of an external field. Herein, we use insitu TEM, electron energy loss spectroscopy, and X-ray photoelectron spectroscopy techniques to record the interaction in palladium on carbon nanotubes (CNTs) from room temperature to 600...

  17. Surface functionalization and biomedical applications based on SiC

    Energy Technology Data Exchange (ETDEWEB)

    Yakimova, R; Petoral, R M Jr; Yazdi, G R; Vahlberg, C; Spetz, A Lloyd; Uvdal, K [Department of Physics, Chemistry and Biology, Linkoeping University, SE-58183 Linkoeping (Sweden)

    2007-10-21

    The search for materials and systems, capable of operating long term under physiological conditions, has been a strategy for many research groups during the past years. Silicon carbide (SiC) is a material, which can meet the demands due to its high biocompatibility, high inertness to biological tissues and to aggressive environment, and the possibility to make all types of electronic devices. This paper reviews progress in biomedical and biosensor related research on SiC. For example, less biofouling and platelet aggregation when exposed to blood is taken advantage of in a variety of medical implantable materials while the robust semiconducting properties can be explored in surface functionalized bioelectronic devices. (review article)

  18. Triboelectric Hydrogen Gas Sensor with Pd Functionalized Surface

    Directory of Open Access Journals (Sweden)

    Sung-Ho Shin

    2016-10-01

    Full Text Available Palladium (Pd-based hydrogen (H2 gas sensors have been widely investigated thanks to its fast reaction and high sensitivity to hydrogen. Various sensing mechanisms have been adopted for H2 gas sensors; however, all the sensors must be powered through an external battery. We report here an H2 gas sensor that can detect H2 by measuring the output voltages generated during contact electrification between two friction surfaces. When the H2 sensor, composed of Pd-coated ITO (indium tin oxide and PET (polyethylene Terephthalate film, is exposed to H2, its output voltage is varied in proportion to H2 concentration because the work function (WF of Pd-coated surface changes, altering triboelectric charging behavior. Specifically, the output voltage of the sensor is gradually increased as exposing H2 concentration increases. Reproducible and sensitive sensor response was observed up 1% H2 exposure. The approach introduced here can easily be adopted to development of triboelectric gas sensors detecting other gas species.

  19. Structures and Functions of Pestivirus Glycoproteins: Not Simply Surface Matters.

    Science.gov (United States)

    Wang, Fun-In; Deng, Ming-Chung; Huang, Yu-Liang; Chang, Chia-Yi

    2015-06-29

    Pestiviruses, which include economically important animal pathogens such as bovine viral diarrhea virus and classical swine fever virus, possess three envelope glycoproteins, namely Erns, E1, and E2. This article discusses the structures and functions of these glycoproteins and their effects on viral pathogenicity in cells in culture and in animal hosts. E2 is the most important structural protein as it interacts with cell surface receptors that determine cell tropism and induces neutralizing antibody and cytotoxic T-lymphocyte responses. All three glycoproteins are involved in virus attachment and entry into target cells. E1-E2 heterodimers are essential for viral entry and infectivity. Erns is unique because it possesses intrinsic ribonuclease (RNase) activity that can inhibit the production of type I interferons and assist in the development of persistent infections. These glycoproteins are localized to the virion surface; however, variations in amino acids and antigenic structures, disulfide bond formation, glycosylation, and RNase activity can ultimately affect the virulence of pestiviruses in animals. Along with mutations that are driven by selection pressure, antigenic differences in glycoproteins influence the efficacy of vaccines and determine the appropriateness of the vaccines that are currently being used in the field.

  20. Structures and Functions of Pestivirus Glycoproteins: Not Simply Surface Matters

    Directory of Open Access Journals (Sweden)

    Fun-In Wang

    2015-06-01

    Full Text Available Pestiviruses, which include economically important animal pathogens such as bovine viral diarrhea virus and classical swine fever virus, possess three envelope glycoproteins, namely Erns, E1, and E2. This article discusses the structures and functions of these glycoproteins and their effects on viral pathogenicity in cells in culture and in animal hosts. E2 is the most important structural protein as it interacts with cell surface receptors that determine cell tropism and induces neutralizing antibody and cytotoxic T-lymphocyte responses. All three glycoproteins are involved in virus attachment and entry into target cells. E1-E2 heterodimers are essential for viral entry and infectivity. Erns is unique because it possesses intrinsic ribonuclease (RNase activity that can inhibit the production of type I interferons and assist in the development of persistent infections. These glycoproteins are localized to the virion surface; however, variations in amino acids and antigenic structures, disulfide bond formation, glycosylation, and RNase activity can ultimately affect the virulence of pestiviruses in animals. Along with mutations that are driven by selection pressure, antigenic differences in glycoproteins influence the efficacy of vaccines and determine the appropriateness of the vaccines that are currently being used in the field.

  1. The Effect of Surface Functionalization on the Immobilization of Gold Nanoparticles on Graphene Sheets

    Directory of Open Access Journals (Sweden)

    Min Song

    2012-01-01

    Full Text Available In our study, graphene oxide is synthesized by Hummers method. And then, carboxylic acid functionalized graphene (graphene-COOH, thiol-functionalized graphene (graphene-SH, and highly dispersive graphene are prepared by chemical modification of respective groups on the graphene surface. Furthermore, we explore a solution-based approach to prepare three differently functionalized graphene-gold composites by one-step chemical reduction of AuCl4 - ions in respective functionalized graphene suspensions, where the gold nanoparticles are deposited on the functionalized graphene surface during their synthesis process. In addition, we compare the influence of surface functionalization on the growth of gold nanoparticles on graphene surface. Transmission electron morphology (TEM and ultraviolet-visible (UV-Vis spectroscopy are employed to study the effect of surface functionalities on AuNPs distribution onto the graphene surface and demonstrate the successful immobilization of AuNPs on graphene surface.

  2. Identification and Evaluation of Integration and Cross Cutting Issues Across HRP Risks

    Science.gov (United States)

    Steinberg, S. L.; Shelhamer, Mark

    2015-01-01

    The HRP Integrated Research Plan contains the research plans for the 32 risks requiring research to characterize and mitigate. These risks to human health and performance in spaceflight are identified by evidence and each one focuses on a single aspect of human physiology or performance. They are further categorized by aspects of the spaceflight environment, such as altered gravity or space radiation, that that play a major role in their likelihood and consequence. From its inception the "integrate" in the Research Plan has denoted the integrated nature of risks to human health and performance, the connectedness of physiological systems within the human body regardless of the spaceflight environment, and the integrated response of the human body to the spaceflight environment. Common characteristics of the spaceflight environment include altered gravity, atmospheres and light/dark cycles, space radiation, isolation, noise, and periods of high or low workload. Long term exposure to this unique environment produces a suite of physiological effects such as stress; vision, neurocognitive and anthropometric changes; circadian misalignment; fluid shifts, deconditioning; immune dysregulation; and altered nutritional requirements. Matrix diagraming was used to systematically identify, analyze and rate the many-to-many relationships between environmental characteristics and the suite of physiological effects. It was also to identify patterns in the relationships of common physiological effects to each other. Analyses of patterns or relationships in these diagrams help to identify issues that cut across multiple risks. Cross cutting issues benefit from a multidisciplinary approach that synthesizes concepts or data from two or more disciplines to identify and characterize risk factors or develop countermeasures relevant to multiple risks. They also help to illuminate possible problem areas that may arise when a countermeasure impacts risks other than those which it was

  3. Multi-functional surfaces with controllable wettability and water adhesion

    Science.gov (United States)

    Anastasiadis, Spiros H.; Frysali, Melani A.; Kenanakis, George; Kaklamani, Georgia; Papoutsakis, Lampros

    The design of multifunctional surfaces based on biomimetic structures has gained the interest of the scientific community. Novel multifunctional surfaces have been developed, able to alter their wetting properties in response to temperature and pH as well as light illumination, by combining proper chemistry and surface micro/nano-structuring using ultrafast (femtosecond) laser irradiation. The combination of the hierarchical surface with a ZnO and/or a responsive polymer coating results in efficient photo-active properties as well as reversible superhydrophobic / superhydrophilic surfaces in response to external stimuli. These surfaces can be optimized to exhibit high or zero water adhesion and/or controllable directionality as well. Moreover, they can be seeded with human fibroblasts to examine the cellular response on both surface roughness and surface chemistry. Acknowledgements: This research has been co-financed by the General Secretariat for Research and Technology (''ARISTEIA II'' Action, SMART-SURF) and the European Union (NFFA Europe -Grant agreement No. 654360).

  4. Investigation of Tooling for Anisotropic Optical Functional Surfaces

    DEFF Research Database (Denmark)

    Li, Dongya; Regi, Francesco; Zhang, Yang

    is assessed by processing the images obtained from a digital microscope Hirox RH-2000 [1]. Figure 1 illustrates the studied surface structure and the microscope. The optical axis of microscope can be tilted within 90 degrees from the horizontal level, which simulates the viewing angle; the analysed surface...

  5. Interactions between acid- and base-functionalized surfaces

    NARCIS (Netherlands)

    Giesbers, M.; Kleijn, J.M.; Cohen Stuart, M.A.

    2002-01-01

    In this paper we present an AFM force study on interactions between chemically modified surfaces. Surfaces with terminal groups of either NH2 or COOH were obtained by chemisorption of a silane-based compound (3-amino-propyltriethoxysilane) on silica or a thiol compound (11-mercapto undecanoic acid)

  6. Testing of newly developed functional surfaces under pure sliding conditions

    DEFF Research Database (Denmark)

    Godi, Alessandro; Mohaghegh, Kamran; Grønbæk, J.

    2013-01-01

    -polished counterpart. A number of experiments were carried out at different normal pressures employing for all specimens the same reciprocating movement and the same lubrication. The measured friction forces were plotted against the incremental normal pressure, and the friction coefficients were calculated....... The results comparison showed clearly how employing multifunctional surfaces can reduce friction forces up to 50 % at high normal loads compared to regularly ground or turned surfaces. Friction coefficients approximately equal to 0.12 were found for classically machined surfaces, whereas the values were 0...... the surfaces in an industrial context. In this paper, a number of experimental tests were performed using a novel test rig, called axial sliding test, simulating the contact of surfaces under pure sliding conditions. The aim of the experiments is to evaluate the frictional behavior of a new typology...

  7. Cytotoxicity of surface-functionalized silicon and germanium nanoparticles: the dominant role of surface charges

    NARCIS (Netherlands)

    Bhattacharjee, S.; Rietjens, I.M.C.M.; Singh, M.P.; Atkins, T.M.; Purkait, T.K.; Xu, Z.; Regli, S.; Shukaliak, A.; Clark, R.J.; Mitchell, B.S.; Alink, G.M.; Marcelis, A.T.M.; Fink, M.J.; Veinot, J.G.C.; Kauzlarich, S.M.; Zuilhof, H.

    2013-01-01

    Although it is frequently hypothesized that surface (like surface charge) and physical characteristics (like particle size) play important roles in cellular interactions of nanoparticles (NPs), a systematic study probing this issue is missing. Hence, a comparative cytotoxicity study, quantifying

  8. A microfluidic surface enhanced Raman spectroscopic biosensor using aptamer functionalized nanopillars

    DEFF Research Database (Denmark)

    Yang, J.; Palla, M.; Bosco, F. G.

    2013-01-01

    This paper presents a microchip incorporating an aptamer-functionalized nanopillar substrate, enabling the specific detection of low-abundance biomolecules using surface enhanced Raman spectroscopy (SERS). In a temperature controlled microchamber, aptamers immobilized on the nanostructure surface...

  9. Covalent organic polymer functionalization of activated carbon surfaces through acyl chloride for environmental clean-up

    DEFF Research Database (Denmark)

    Mines, Paul D.; Thirion, Damien; Uthuppu, Basil

    2017-01-01

    Nanoporous networks of covalent organic polymers (COPs) are successfully grafted on the surfaces of activated carbons, through a series of surface modification techniques, including acyl chloride formation by thionyl chloride. Hybrid composites of activated carbon functionalized with COPs exhibit...

  10. Process chain for fabrication of anisotropic optical functional surfaces on polymer components

    DEFF Research Database (Denmark)

    Li, Dongya; Zhang, Yang; Regi, Francesco

    2017-01-01

    This paper aims to introduce a process chain for fabrication of anisotropic optical functional surfaces on polymer products. Thesurface features under investigation are composed of micro serrated ridges. The scope was to maximize the visible contrast betweenhorizontally orthogonal textured surfaces...

  11. Functional surface chemistry of carbon-based nanostructures

    Science.gov (United States)

    Abdula, Daner

    The recently discovered abilities to synthesize single-walled carbon nanotubes and prepare single layer graphene have spurred interest in these sp2-bonded carbon nanostructures. In particular, studies of their potential use in electronic devices are many as silicon integrated circuits are encountering processing limitations, quantum effects, and thermal management issues due to rapid device scaling. Nanotube and graphene implementation in devices does come with significant hurdles itself. Among these issues are the ability to dope these materials and understanding what influences defects have on expected properties. Because these nanostructures are entirely all-surface, with every atom exposed to ambient, introduction of defects and doping by chemical means is expected to be an effective route for addressing these issues. Raman spectroscopy has been a proven characterization method for understanding vibrational and even electronic structure of graphene, nanotubes, and graphite, especially when combined with electrical measurements, due to a wealth of information contained in each spectrum. In Chapter 1, a discussion of the electronic structure of graphene is presented. This outlines the foundation for all sp2-bonded carbon electronic properties and is easily extended to carbon nanotubes. Motivation for why these materials are of interest is readily gained. Chapter 2 presents various synthesis/preparation methods for both nanotubes and graphene, discusses fabrication techniques for making devices, and describes characterization methods such as electrical measurements as well as static and time-resolved Raman spectroscopy. Chapter 3 outlines changes in the Raman spectra of individual metallic single-walled carbon nantoubes (SWNTs) upon sidewall covalent bond formation. It is observed that the initial degree of disorder has a strong influence on covalent sidewall functionalization which has implications on developing electronically selective covalent chemistries and

  12. Microwave assisted organic modification and surface functionalization of Phyllosilicates

    CSIR Research Space (South Africa)

    Kesavan Pillai, Sreejarani

    2012-11-01

    Full Text Available Organically modified phyllosilicates (montmorillonite and palygorskite) using Arquad 2HT-75 surfactant were effectively synthesized utilizing a microwave irradiation technique. The microwave method was successfully used also for the surface...

  13. A novel biosensor based on boronic acid functionalized metal-organic frameworks for the determination of hydrogen peroxide released from living cells.

    Science.gov (United States)

    Dai, Hongxia; Lü, Wenjuan; Zuo, Xianwei; Zhu, Qian; Pan, Congjie; Niu, Xiaoying; Liu, Juanjuan; Chen, HongLi; Chen, Xingguo

    2017-09-15

    In this work, we report a durable and sensitive H 2 O 2 biosensor based on boronic acid functionalized metal-organic frameworks (denoted as MIL-100(Cr)-B) as an efficient immobilization matrix of horseradish peroxidase (HRP). MIL-100(Cr)-B features a hierarchical porous structure, extremely high surface area, and sufficient recognition sites, which can significantly increase HRP loading and prevent them from leakage and deactivation. The H 2 O 2 biosensor can be easily achieved without any complex processing. Meanwhile, the immobilized HRP exhibited enhanced stability and remarkable catalytic activity towards H 2 O 2 reduction. Under optimal conditions, the biosensor showed a fast response time (less than 4s) to H 2 O 2 in a wide linear range of 0.5-3000μM with a low detection limit of 0.1μM, as well as good anti-interference ability and long-term storage stability. These excellent performances substantially enable the proposed biosensor to be used for the real-time detection of H 2 O 2 released from living cells with satisfactory results, thus showing the potential application in the study of H 2 O 2 -involved dynamic pathological and physiological process. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Adsorption of surface functionalized silica nanoparticles onto mineral surfaces and decane/water interface

    International Nuclear Information System (INIS)

    Metin, Cigdem O.; Baran, Jimmie R.; Nguyen, Quoc P.

    2012-01-01

    The adsorption of silica nanoparticles onto representative mineral surfaces and at the decane/water interface was studied. The effects of particle size (the mean diameters from 5 to 75 nm), concentration and surface type on the adsorption were studied in detail. Silica nanoparticles with four different surfaces [unmodified, surface modified with anionic (sulfonate), cationic (quaternary ammonium (quat)) or nonionic (polyethylene glycol (PEG)) surfactant] were used. The zeta potential of these silica nanoparticles ranges from −79.8 to 15.3 mV. The shape of silica particles examined by a Hitachi-S5500 scanning transmission electron microscope (STEM) is quite spherical. The adsorption of all the nanoparticles (unmodified or surface modified) on quartz and calcite surfaces was found to be insignificant. We used interfacial tension (IFT) measurements to investigate the adsorption of silica nanoparticles at the decane/water interface. Unmodified nanoparticles or surface modified ones with sulfonate or quat do not significantly affect the IFT of the decane/water interface. It also does not appear that the particle size or concentration influences the IFT. However, the presence of PEG as a surface modifying material significantly reduces the IFT. The PEG surface modifier alone in an aqueous solution, without the nanoparticles, yields the same IFT reduction for an equivalent PEG concentration as that used for modifying the surface of nanoparticles. Contact angle measurements of a decane droplet on quartz or calcite plate immersed in water (or aqueous nanoparticle dispersion) showed a slight change in the contact angle in the presence of the studied nanoparticles. The results of contact angle measurements are in good agreement with experiments of adsorption of nanoparticles on mineral surfaces or decane/water interface. This study brings new insights into the understanding and modeling of the adsorption of surface-modified silica nanoparticles onto mineral surfaces and

  15. First-principles Green's-function method for surface calculations: A pseudopotential localized basis set approach

    Science.gov (United States)

    Smidstrup, Søren; Stradi, Daniele; Wellendorff, Jess; Khomyakov, Petr A.; Vej-Hansen, Ulrik G.; Lee, Maeng-Eun; Ghosh, Tushar; Jónsson, Elvar; Jónsson, Hannes; Stokbro, Kurt

    2017-11-01

    We present an efficient implementation of a surface Green's-function method for atomistic modeling of surfaces within the framework of density functional theory using a pseudopotential localized basis set approach. In this method, the system is described as a truly semi-infinite solid with a surface region coupled to an electron reservoir, thereby overcoming several fundamental drawbacks of the traditional slab approach. The versatility of the method is demonstrated with several applications to surface physics and chemistry problems that are inherently difficult to address properly with the slab method, including metal work function calculations, band alignment in thin-film semiconductor heterostructures, surface states in metals and topological insulators, and surfaces in external electrical fields. Results obtained with the surface Green's-function method are compared to experimental measurements and slab calculations to demonstrate the accuracy of the approach.

  16. Atomic Resolution Imaging and Quantification of Chemical Functionality of Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, Udo D. [Yale Univ., New Haven, CT (United States). Dept. of Mechanical Engineering and Materials Science; Altman, Eric I. [Yale Univ., New Haven, CT (United States). Dept. of Chemical and Environmental Engineering

    2014-12-10

    The work carried out from 2006-2014 under DoE support was targeted at developing new approaches to the atomic-scale characterization of surfaces that include species-selective imaging and an ability to quantify chemical surface interactions with site-specific accuracy. The newly established methods were subsequently applied to gain insight into the local chemical interactions that govern the catalytic properties of model catalysts of interest to DoE. The foundation of our work was the development of three-dimensional atomic force microscopy (3DAFM), a new measurement mode that allows the mapping of the complete surface force and energy fields with picometer resolution in space (x, y, and z) and piconewton/millielectron volts in force/energy. From this experimental platform, we further expanded by adding the simultaneous recording of tunneling current (3D-AFM/STM) using chemically well-defined tips. Through comparison with simulations, we were able to achieve precise quantification and assignment of local chemical interactions to exact positions within the lattice. During the course of the project, the novel techniques were applied to surface-oxidized copper, titanium dioxide, and silicon oxide. On these materials, defect-induced changes to the chemical surface reactivity and electronic charge density were characterized with site-specific accuracy.

  17. Improved adhesion of Ag NPs to the polyethylene terephthalate surface via atmospheric plasma treatment and surface functionalization

    Science.gov (United States)

    Shen, Tao; Liu, Yong; Zhu, Yan; Yang, De-Quan; Sacher, Edward

    2017-07-01

    Ag nanoparticles (NPs) have been widely applied, as important antibacterial materials, on textile and polymer surfaces. However, their adhesion to nonreactive polymer surfaces is generally too weak for many applications. Here, we propose a two-step process, atmospheric plasma treatment followed by a surface chemical modification process, which enhances their adhesion to polyethylene terephthalate (PET) surfaces. We found that, compared to either plasma treatments or surface chemical functionalizations, alone, this combination greatly enhanced their adhesion. The plasma treatment resulted in an increase of active sites (sbnd OH, sbnd CHdbnd O and COOH) at the PET surface, permitting increased bonding to 3-aminopropyltriethoxysilane (APTES), whose sbnd NH2 groups were then able to form a bonding complex with the Ag NPs.

  18. How modification of accessible lysines to phenylalanine modulates the structural and functional properties of horseradish peroxidase: a simulation study.

    Directory of Open Access Journals (Sweden)

    Leila Navapour

    Full Text Available Horseradish Peroxidase (HRP is one of the most studied peroxidases and a great number of chemical modifications and genetic manipulations have been carried out on its surface accessible residues to improve its stability and catalytic efficiency necessary for biotechnological applications. Most of the stabilized derivatives of HRP reported to date have involved chemical or genetic modifications of three surface-exposed lysines (K174, K232 and K241. In this computational study, we altered these lysines to phenylalanine residues to model those chemical modifications or genetic manipulations in which these positively charged lysines are converted to aromatic hydrophobic residues. Simulation results implied that upon these substitutions, the protein structure becomes less flexible. Stability gains are likely to be achieved due to the increased number of stable hydrogen bonds, improved heme-protein interactions and more integrated proximal Ca2+ binding pocket. We also found a new persistent hydrogen bond between the protein moiety (F174 and the heme prosthetic group as well as two stitching hydrogen bonds between the connecting loops GH and F'F″ in mutated HRP. However, detailed analysis of functionally related structural properties and dynamical features suggests reduced reactivity of the enzyme toward its substrates. Molecular dynamics simulations showed that substitutions narrow the bottle neck entry of peroxide substrate access channel and reduce the surface accessibility of the distal histidine (H42 and heme prosthetic group to the peroxide and aromatic substrates, respectively. Results also demonstrated that the area and volume of the aromatic-substrate binding pocket are significantly decreased upon modifications. Moreover, the hydrophobic patch functioning as a binding site or trap for reducing aromatic substrates is shrunk in mutated enzyme. Together, the results of this simulation study could provide possible structural clues to explain

  19. On Approximations of Compact Sets of Functions by Algebraic Surfaces

    Science.gov (United States)

    Kudryavtsev, S. N.

    1986-06-01

    This article deals with approximations of certain compact sets of smooth and analytic functions by families of functions depending in a polynomial fashion on parameters. The connection between the accuracy of the approximations of the compact sets by such families and the number of parameters and their degree is studied. Bibliography: 3 titles.

  20. Frequency Selective Surfaces for extended Bandwidth backing reflector functions

    NARCIS (Netherlands)

    Pasian, M.; Neto, A.; Monni, S.; Ettorre, M.; Gerini, G.

    2008-01-01

    This paper deals with the use of Frequency Selective Surfaces (FSS) to increase the Efficiency × Bandwidth product in Ultra-Wide Band (UWB) antenna arrays whose efficiency is limited by the front-to-back ratio. If the backing reflector is realized in one metal plane solution its location will be

  1. Density functional theory in surface chemistry and catalysis

    Science.gov (United States)

    Nørskov, Jens K.; Abild-Pedersen, Frank; Studt, Felix; Bligaard, Thomas

    2011-01-01

    Recent advances in the understanding of reactivity trends for chemistry at transition-metal surfaces have enabled in silico design of heterogeneous catalysts in a few cases. The current status of the field is discussed with an emphasis on the role of coupling theory and experiment and future challenges. PMID:21220337

  2. Density functional theory in surface chemistry and catalysis

    DEFF Research Database (Denmark)

    Nørskov, Jens Kehlet; Abild-Pedersen, Frank; Studt, Felix

    2011-01-01

    Recent advances in the understanding of reactivity trends for chemistry at transition-metal surfaces have enabled in silico design of heterogeneous catalysts in a few cases. The current status of the field is discussed with an emphasis on the role of coupling theory and experiment and future...

  3. Density Functional Theory in Surface Chemistry and Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Norskov, Jens

    2011-05-19

    Recent advances in the understanding of reactivity trends for chemistry at transition metal surfaces have enabled in silico design of heterogeneous catalysts in a few cases. Current status of the field is discussed with an emphasis on the role of coupling between theory and experiment and future challenges.

  4. Surface functionalization of HF-treated silicon nanowires

    Indian Academy of Sciences (India)

    Administrator

    tron-transfer mediator and immobilizing matrices for biological or chemical molecules. 22. The chemical properties of SiNWs surfaces are crucial to their application in mesoscopic electronic devices in terms of stability and transport properties. Currently, many studies have been involved in the modification and reactivity of ...

  5. Functionalized Palladium Nanoparticles for Hydrogen Peroxide Biosensor

    Directory of Open Access Journals (Sweden)

    H. Baccar

    2011-01-01

    Full Text Available We present a comparison between two biosensors for hydrogen peroxide (H2O2 detection. The first biosensor was developed by the immobilization of Horseradish Peroxidase (HRP enzyme on thiol-modified gold electrode. The second biosensor was developed by the immobilization of cysteamine functionalizing palladium nanoparticles on modified gold surface. The amino groups can be activated with glutaraldehyde for horseradish peroxidase immobilization. The detection of hydrogen peroxide was successfully observed in PBS for both biosensors using the cyclic voltammetry and the chronoamperometry techniques. The results show that the limit detection depends on the large surface-to-volume ratio attained with palladium nanoparticles. The second biosensor presents a better detection limit of 7.5 μM in comparison with the first one which is equal to 75 μM.

  6. Vitamin D, surface electromyography and physical function in uraemic patients

    DEFF Research Database (Denmark)

    Heaf, J.G.; Mølsted, Stig; Harrison, Adrian Paul

    2010-01-01

    ) under voluntary contractions. Physical function was determined using a 30-second Chair Stand Test and the Short Form 36 quality of life questionnaire. Clinical characteristics were collected from the patient records. Results: Moderate vitamin 25-OHD deficiency (

  7. Structure Function Studies of Vaccinia Virus Host Range Protein K1 Reveal a Novel Functional Surface for Ankyrin Repeat Proteins

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yongchao; Meng, Xiangzhi; Xiang, Yan; Deng, Junpeng (Texas-HSC); (OKLU)

    2010-06-15

    Poxvirus host tropism at the cellular level is regulated by virus-encoded host range proteins acting downstream of virus entry. The functioning mechanisms of most host range proteins are unclear, but many contain multiple ankyrin (ANK) repeats, a motif that is known for ligand interaction through a concave surface. We report here the crystal structure of one of the ANK repeat-containing host range proteins, the vaccinia virus K1 protein. The structure, at a resolution of 2.3 {angstrom}, showed that K1 consists entirely of ANK repeats, including seven complete ones and two incomplete ones, one each at the N and C terminus. Interestingly, Phe82 and Ser83, which were previously shown to be critical for K1's function, are solvent exposed and located on a convex surface, opposite the consensus ANK interaction surface. The importance of this convex surface was further supported by our additional mutagenesis studies. We found that K1's host range function was negatively affected by substitution of either Asn51 or Cys47 and completely abolished by substitution of both residues. Cys47 and Asn51 are also exposed on the convex surface, spatially adjacent to Phe82 and Ser83. Altogether, our data showed that K1 residues on a continuous convex ANK repeat surface are critical for the host range function, suggesting that K1 functions through ligand interaction and does so with a novel ANK interaction surface.

  8. Measurements of long-range interactions between protein-functionalized surfaces by total internal reflection microscopy.

    Science.gov (United States)

    Wang, Zhaohui; Gong, Xiangjun; Ngai, To

    2015-03-17

    Understanding the interaction between protein-functionalized surfaces is an important subject in a variety of protein-related processes, ranging from coatings for biomedical implants to targeted drug carriers and biosensors. In this work, utilizing a total internal reflection microscope (TIRM), we have directly measured the interactions between micron-sized particles decorated with three types of common proteins concanavalin A (ConA), bovine serum albumin (BSA), lysozyme (LYZ), and glass surface coated with soy proteins (SP). Our results show that the protein adsorption greatly affects the charge property of the surfaces, and the interactions between those protein-functionalized surfaces depend on solution pH values. At pH 7.5-10.0, all these three protein-functionalized particles are highly negatively charged, and they move freely above the negatively charged SP-functionalized surface. The net interaction between protein-functionalized surfaces captured by TIRM was found as a long-range, nonspecific double-layer repulsion. When pH was decreased to 5.0, both protein-functionalized surfaces became neutral and double-layer repulsion was greatly reduced, resulting in adhesion of all three protein-functionalized particles to the SP-functionalized surface due to the hydrophobic attraction. The situation is very different at pH = 4.0: BSA-decorated particles, which are highly charged, can move freely above the SP-functionalized surfaces, while ConA- and LYZ-decorated particles can only move restrictively in a limited range. Our results quantify these nonspecific kT-scale interactions between protein-functionalized surfaces, which will enable the design of surfaces for use in biomedical applications and study of biomolecular interactions.

  9. An expert system to characterize the surface morphological properties according to their functionalities

    International Nuclear Information System (INIS)

    Bigerelle, M; Mathia, T; Iost, A; Correvits, T; Anselme, K

    2011-01-01

    In this paper we propose a new methodology to characterize the morphological properties of a surface in relation with its functionality (tribological properties, surface coating adhesion, brightness, wettability...). We create a software based on experimental design and surface profile recording. Using an appropriate database structure, the roughness parameters are automatically computed at different scales. The surface files are saved in a hard disk directory and roughness parameters are computed at different scales. Finally, a statistical analysis system proposes the roughness parameter (or the pair of roughness parameters) that better describe(s) the functionality of the surface and the spatial scales at which the parameter(s) is (are) the more relevant.

  10. Primary role of electron work function for evaluation of nanostructured titania implant surface against bacterial infection

    Energy Technology Data Exchange (ETDEWEB)

    Golda-Cepa, M., E-mail: golda@chemia.uj.edu.pl [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Syrek, K. [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Brzychczy-Wloch, M. [Department of Bacteriology, Microbial Ecology and Parasitology, Jagiellonian University Medical College, Czysta 18, 31-121 Krakow (Poland); Sulka, G.D. [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Kotarba, A., E-mail: kotarba@chemia.uj.edu.pl [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland)

    2016-09-01

    The electron work function as an essential descriptor for the evaluation of metal implant surfaces against bacterial infection is identified for the first time. Its validity is demonstrated on Staphylococcus aureus adhesion to nanostructured titania surfaces. The established correlation: work function–bacteria adhesion is of general importance since it can be used for direct evaluation of any electrically conductive implant surfaces. - Highlights: • The correlation between work function and bacteria adhesion was discovered. • The discovered correlation is rationalized in terms of electrostatic bacteria–surface repulsion. • The results provide basis for the simple evaluation of implant surfaces against infection.

  11. An expert system to characterize the surface morphological properties according to their functionalities

    Energy Technology Data Exchange (ETDEWEB)

    Bigerelle, M [Laboratoire Roberval, UMR 6253, UTC/CNRS, UTC Centre de Recherches de Royallieu BP 20529, 60205 Compiegne France stol BS1 6BE (United Kingdom); Mathia, T [Laboratoire de Tribologie et Dynamique des Systemes, UMR 5513, Ecole Centrale de Lyon, 36 Av Guy de Collongue, 69134 Ecully Cedex (France); Iost, A [Laboratoire de Mecanique de Lille, UMR CNRS 8107, Arts et Metiers ParisTech - Lille, 8, boulevard Louis XIV 59046 Lille (France); Correvits, T [Laboratoire de Metrologie. Arts et Metiers ParisTech, ENSAM, 8 boulevard Louis XIV, 59046 LILLE Cedex (France); Anselme, K, E-mail: maxence.bigerelle@utc.fr [Institut De Sciences Des Materiaux De Mulhouse, CNRS LRC 7228, 15, rue Jean Starcky, Universite De Haute-Alsace, BP 2488, 68057 Mulhouse (France)

    2011-08-19

    In this paper we propose a new methodology to characterize the morphological properties of a surface in relation with its functionality (tribological properties, surface coating adhesion, brightness, wettability...). We create a software based on experimental design and surface profile recording. Using an appropriate database structure, the roughness parameters are automatically computed at different scales. The surface files are saved in a hard disk directory and roughness parameters are computed at different scales. Finally, a statistical analysis system proposes the roughness parameter (or the pair of roughness parameters) that better describe(s) the functionality of the surface and the spatial scales at which the parameter(s) is (are) the more relevant.

  12. Recent advances in surface functionalization techniques on polymethacrylate materials for optical biosensor applications.

    Science.gov (United States)

    Hosseini, Samira; Ibrahim, Fatimah; Djordjevic, Ivan; Koole, Leo H

    2014-06-21

    Biosensor chips for immune-based assay systems have been investigated for their application in early diagnostics. The development of such systems strongly depends on the effective protein immobilization on polymer substrates. In order to achieve this complex heterogeneous interaction the polymer surface must be functionalized with chemical groups that are reactive towards proteins in a way that surface functional groups (such as carboxyl, -COOH; amine, -NH2; and hydroxyl, -OH) chemically or physically anchor the proteins to the polymer platform. Since the proteins are very sensitive towards their environment and can easily lose their activity when brought in close proximity to the solid surface, effective surface functionalization and high level of control over surface chemistry present the most important steps in the fabrication of biosensors. This paper reviews recent developments in surface functionalization and preparation of polymethacrylates for protein immobilization. Due to their versatility and cost effectiveness, this particular group of plastic polymers is widely used both in research and in industry.

  13. Graphs on Surfaces and the Partition Function of String Theory

    OpenAIRE

    Garcia-Islas, J. Manuel

    2007-01-01

    Graphs on surfaces is an active topic of pure mathematics belonging to graph theory. It has also been applied to physics and relates discrete and continuous mathematics. In this paper we present a formal mathematical description of the relation between graph theory and the mathematical physics of discrete string theory. In this description we present problems of the combinatorial world of real importance for graph theorists. The mathematical details of the paper are as follows: There is a com...

  14. Development of smart functional surfaces for biosensor applications

    Science.gov (United States)

    Sokkalinga Balasubramanian, Shankar Ganesh

    Biosensing platforms and antimicrobial coatings were developed to combat problems associated with infectious diseases. Particularly, a lytic bacteriophage based surface plasmon resonance (SPR) biosensor was developed to detect food borne pathogen Staphylococcus aureus (S.aureus) in real-time with high specificity. Lytic bacteriophages are naturally developed molecular probes that infect bacteria. They are environmentally stable and inexpensive to produce compared to commercially available antibodies. The sensitivity of SPR biosensors were further improved specifically by poly-L-lysine grafted polyethylene glycol (PLL-g-PEG) polymer. This polymer reduces non-specific adsorption of S.aureus on SPR gold surface by ˜97%. When used as a blocking buffer in affinity sensing of model antigen, beta-galactosidase by filamentous bacteriophage, this polymer improved the detection sensitivity by 2 to 3 orders of magnitude. A facile approach was developed for sensor surface regeneration by controlling the immobilization and removal of antibodies from SPR gold surface. This was facilitated by the electro-reductive nature of alkanethiols. By combining SPR with electrochemical methods, the molecular assembly/disassembly processes were monitored in real-time with great control. Finally, single-walled carbon nanotube (SWNT) biocomposites were prepared using DNA and lysozyme (LSZ) to develop mechanically strong antimicrobial coatings. Coulombic interactions between DNA and LSZ were exploited to fabricate multilayer antimicrobial coatings using a technique called layer-by-layer assembly. This produced large scale biomimetic coatings with significant antimicrobial activity, high Young's modulus and controlled morphology which combines the individual attributes of SWNTs and natural materials.

  15. Functionalization of silicon crystal surface by energetic cluster ion bombardment

    Czech Academy of Sciences Publication Activity Database

    Lavrentiev, Vasyl; Vacík, Jiří; Dejneka, Alexandr; Jastrabík, Lubomír; Vorlíček, Vladimír; Chvostová, Dagmar; Potůček, Zdeněk; Narumi, K.; Naramoto, H.

    2012-01-01

    Roč. 12, č. 12 (2012), s. 9136-9141 ISSN 1533-4880 R&D Projects: GA AV ČR(CZ) KAN400480701; GA ČR GA106/09/1264; GA ČR(CZ) GBP108/12/G108 Institutional support: RVO:61389005 ; RVO:68378271 Keywords : cluster impacts * silicon * surface * quantum dots * light emission Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.149, year: 2012

  16. Relationships between surface energy analysis and functional characteristics of dairy powders.

    Science.gov (United States)

    Kondor, Anett; Hogan, Sean A

    2017-12-15

    Surface energetics of demineralised whey (DMW), skimmed milk (SMP), phosphocasein (PCN) and infant milk formula (IMF) powders were determined by inverse gas chromatography (IGC). All four milk powders were amphoteric in nature with the dispersive (apolar) component of surface energy dominating the specific (polar) contribution. PCN and IMF had the highest and lowest extent of surface heterogeneity, respectively. PCN also demonstrated the poorest functional properties of the powders examined. In contrast, IMF had excellent flow and rehydration properties. Thermodynamic work of cohesion was highest in PCN and may have contributed to inadequate rehydration behaviour. Glass transition temperature of IMF powder, determined by IGC, suggested a surface dominated by lactose. Surface heterogeneity provided a better indicator of functional behaviour than total surface energy. IGC is a useful complementary technique for chemical and structural analysis of milk powders and allows improved insight into the contribution of surface and bulk factors to functionality. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Improved adhesion of Ag NPs to the polyethylene terephthalate surface via atmospheric plasma treatment and surface functionalization

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Tao [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, 253 Xuefu Rd, Kunming, Yunnan, 650093 (China); Liu, Yong [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, 253 Xuefu Rd, Kunming, Yunnan, 650093 (China); Solmont Technology Wuxi Co., Ltd. 228 Linghu Blvd. Tianan Tech Park, A1-602, Xinwu District, Wuxi, Jiangsu 214135 (China); Zhu, Yan, E-mail: zhuyan@kmust.edu.cn [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, 253 Xuefu Rd, Kunming, Yunnan, 650093 (China); Yang, De-Quan, E-mail: dequan.yang@gmail.com [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, 253 Xuefu Rd, Kunming, Yunnan, 650093 (China); Solmont Technology Wuxi Co., Ltd. 228 Linghu Blvd. Tianan Tech Park, A1-602, Xinwu District, Wuxi, Jiangsu 214135 (China); Sacher, Edward [Regroupement Québécois de Matériaux de Pointe, Department of Engineering Physics, École Polytechnique de Montréal, Case Postale 6079, succursale Centre-Ville, Montréal, Québec H3C 3A7 (Canada)

    2017-07-31

    Highlights: • A two-step process has been developed to enhance the adhesion of immobilized Ag NPs to the PET surface. • The method is simple, easy to use and low-cost for mass production. • The increased density of active sites (−OH, −CH=O and COOH) at the PET surface, after plasma treatment, permits increased reaction with 3-aminopropyltriethoxysilane (APTES). • The presence of APTES with high surface density permits −NH{sub 2}-Ag complex formation, increasing the adhesion of the Ag NPs. - Abstract: Ag nanoparticles (NPs) have been widely applied, as important antibacterial materials, on textile and polymer surfaces. However, their adhesion to nonreactive polymer surfaces is generally too weak for many applications. Here, we propose a two-step process, atmospheric plasma treatment followed by a surface chemical modification process, which enhances their adhesion to polyethylene terephthalate (PET) surfaces. We found that, compared to either plasma treatments or surface chemical functionalizations, alone, this combination greatly enhanced their adhesion. The plasma treatment resulted in an increase of active sites (−OH, −CH=O and COOH) at the PET surface, permitting increased bonding to 3-aminopropyltriethoxysilane (APTES), whose −NH{sub 2} groups were then able to form a bonding complex with the Ag NPs.

  18. Affinity Induced Surface Functionalization of Liposomes Using Cu-Free Click Chemistry

    DEFF Research Database (Denmark)

    Bak, Martin; Jølck, Rasmus Irming; Eliasen, Rasmus

    2016-01-01

    be used for functionalization of other nanoparticles or solid surfaces. The method exploits a synergistic effect of having both affinity and covalent anchoring tags on the surface of the liposome. This was achieved by synthesizing a peptide linker system that uses Cu-free strain-promoted click chemistry.......2%. The reaction kinetics and overall yield were quantified by HPLC. The results presented here open new possibilities for constructing complex nanostructures and functionalized surfaces....

  19. Superparamagnetic bead interactions with functionalized surfaces characterized by an immunomicroarray

    DEFF Research Database (Denmark)

    Skottrup, Peter Durand; Hansen, Mikkel Fougt; Moresco, Jacob Lange

    2010-01-01

    Magneto-resistive sensors capable of detecting superparamagnetic micro-/nano-sized beads are promising alternatives to standard diagnostic assays based on absorbance or fluorescence and streptavidin-functionalized beads are widely used as an integral part of these sensors. Here we have developed ...

  20. Tunable Oxygen Functional Groups as Electrocatalysts on Graphite Felt Surfaces for All-Vanadium Flow Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Estevez, Luis [Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999 Richland WA 99352 USA; Reed, David [Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999 Richland WA 99352 USA; Nie, Zimin [Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999 Richland WA 99352 USA; Schwarz, Ashleigh M. [Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999 Richland WA 99352 USA; Nandasiri, Manjula I. [Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999 Richland WA 99352 USA; Kizewski, James P. [Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999 Richland WA 99352 USA; Wang, Wei [Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999 Richland WA 99352 USA; Thomsen, Edwin [Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999 Richland WA 99352 USA; Liu, Jun [Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999 Richland WA 99352 USA; Zhang, Ji-Guang [Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999 Richland WA 99352 USA; Sprenkle, Vincent [Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999 Richland WA 99352 USA; Li, Bin [Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999 Richland WA 99352 USA

    2016-05-17

    We decorated the surfaces of graphite felts with some oxygen-containing functional groups, such as C-OH, O=C and HO-C=O. And the mole ratios and amounts of these functional groups were effectively adjusted on the graphite surface by a particular method. The catalytic effects of amounts and mole ratio of different kinds of functional groups on VRB electrode performances were investigated in detail.

  1. Modulation effect of hydrogen and fluorine decoration on the surface work function of BN sheets

    Directory of Open Access Journals (Sweden)

    N Jiao

    2012-06-01

    Full Text Available Using first-principles calculations within the framework of density-functional theory, we studied the modulation effect of hydrogen/fluorine chemical decoration on the surface work function of BN sheets. We found that the difference in the work function (ΔWBN between two surfaces of the chair structure varies with the different decoration. Geometric distortion and chemical effects cause opposite modulation effects, and the chemical effect plays a leading role by inducing charge redistribution in the system.

  2. Surface Tension of Nonideal Binary Liquid Mixtures as a Function of Composition.

    Science.gov (United States)

    Nath

    1999-01-01

    The composition dependence of the surface tension of highly nonideal organic-organic and aqueous-organic nonelectrolyte solutions is described, based on the assumption that the surface layer can be treated as a separate phase located between vapor and bulk liquid phases. The Wilson, NRTL, and UNIFAC methods are used for activity coefficients of surface and bulk phases and three techniques for calculation of molar surface areas, based on Paquette areas, Rasmussen areas, and a Langmuir-type approach are tested. Comparisons of the calculated surface tensions with experimental data yield mean absolute errors, in the best case, of less than 2.5% for the systems studied, all of which exhibit highly nonideal behavior. The surface tension predictions are found to be extremely sensitive to the values of the molar surface areas used in the computation. A Langmuir-type adsorption model is formulated to determine the surface mole fractions from a knowledge of the mixture surface tension as a function of bulk composition. A novel procedure is developed to obtain the partial molar surface area of the larger organic component as a function of composition in binary aqueous-organic systems, assuming that the two components are very dissimilar in size, and that deviations in the partial molar surface area of the smaller component (water) from its pure component molar surface area contribute negligibly to the total molar surface area of the mixture. This removes the approximation of equality of partial and pure component molar surface area for the larger organic component. Use of the Langmuir-type approach with partial molar surface areas improves surface tension predictions of highly nonideal aqueous-organic mixtures by 20% over use of pure component molar surface areas. It is an important first step in the development of a thermodynamically consistent theory of surfaces for liquid mixtures based on an accurate determination of the composition dependence of partial molar surface

  3. Surface regulated arsenenes as Dirac materials: From density functional calculations

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Junhui; Xie, Qingxing; Yu, Niannian, E-mail: niannianyu@whut.edu.cn; Wang, Jiafu, E-mail: jasper@whut.edu.cn

    2017-02-01

    Highlights: • The presence of Dirac cones in chemically decorated buckled arsenene AsX (X = CN, NC, NCO, NCS, and NCSe) has been revealed. • First-principles calculations show that all these chemically decorated arsenenes are kinetically stable in defending thermal fluctuations in room temperature. - Abstract: Using first principle calculations based on density functional theory (DFT), we have systematically investigated the structure stability and electronic properties of chemically decorated arsenenes, AsX (X = CN, NC, NCO, NCS and NCSe). Phonon dispersion and formation energy analysis reveal that all the five chemically decorated buckled arsenenes are energetically favorable and could be synthesized. Our study shows that wide-bandgap arsenene would turn into Dirac materials when functionalized by -X (X = CN, NC, NCO, NCS and NCSe) groups, rendering new promises in next generation high-performance electronic devices.

  4. An investigation of the functional groups on the surface of activated carbons

    Directory of Open Access Journals (Sweden)

    MARYTE DERVINYTE

    2004-05-01

    Full Text Available Activated carbons were produced in the laboratory from wood using a 20-run Plackett–Burman experimental design for 19 factors. The obtained batches of activated carbon were analysed by potentiometric titration and FTIR spectroscopy to determine the surface functional groups. The results obtained by potentiometric titration displayed the distribution of individual acidity constants of those groups in the pK range. Considering this parameter, the surface functional groups were divided into carboxyl, lactone and phenol. The linear regression equations reflecting the influence of each operation used for the synthesis on the amount of these functional groups in the obtained activated carbons were generated. The FTIR spectra were used in parallel for the evaluation of the amount and the type of the surface functional groups. Relationships between the two data sets obtained by potentiometric titration and FTIR spectroscopy were evaluated by correlation analysis. It was established that the amount of surface functional groups determined by potentiometric titration positively correlates with the intensity of the peaks of hydrophilic functional groups in the FTIR spectra. At the same time, the negative correlation between potentiometrically determined amount of surface functional groups and the intensity of peaks of hydrophobic functional groups was observed. Most probably, these non-polar formations can take part in the interaction of carbon surface with H+/OH- ions and diminish the strength of existent functional groups.

  5. Surface structure and properties of functionalized nanodiamonds: a first-principles study

    Energy Technology Data Exchange (ETDEWEB)

    Datta, Aditi; Kirca, Mesut; Fu Yao; To, Albert C, E-mail: albertto@pitt.edu [Department of Mechanical Engineering and Materials Science and Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States)

    2011-02-11

    The goal of this work is to gain fundamental understanding of the surface and internal structure of functionalized detonation nanodiamonds (NDs) using quantum mechanics based density functional theory (DFT) calculations. The unique structure of ND assists in the binding of different functional groups to its surface which in turn facilitates binding with drug molecules. The ability to comprehensively model the surface properties, as well as drug-ND interactions during functionalization, is a challenge and is the problem of our interest. First, the structure of NDs of technologically relevant size ({approx}5 nm) was optimized using classical mechanics based molecular mechanics simulations. Quantum mechanics based density functional theory (DFT) was then employed to analyse the properties of smaller relevant parts of the optimized cluster further to address the effect of functionalization on the stability of the cluster and reactivity at its surface. It is found that functionalization is preferred over reconstruction at the (100) surface and promotes graphitization in the (111) surface for NDs functionalized with the carbonyl oxygen (C = O) group. It is also seen that the edges of ND are the preferred sites for functionalization with the carboxyl group (-COOH) vis-a-vis the corners of ND.

  6. Surface structure and properties of functionalized nanodiamonds: a first-principles study

    International Nuclear Information System (INIS)

    Datta, Aditi; Kirca, Mesut; Fu Yao; To, Albert C

    2011-01-01

    The goal of this work is to gain fundamental understanding of the surface and internal structure of functionalized detonation nanodiamonds (NDs) using quantum mechanics based density functional theory (DFT) calculations. The unique structure of ND assists in the binding of different functional groups to its surface which in turn facilitates binding with drug molecules. The ability to comprehensively model the surface properties, as well as drug-ND interactions during functionalization, is a challenge and is the problem of our interest. First, the structure of NDs of technologically relevant size (∼5 nm) was optimized using classical mechanics based molecular mechanics simulations. Quantum mechanics based density functional theory (DFT) was then employed to analyse the properties of smaller relevant parts of the optimized cluster further to address the effect of functionalization on the stability of the cluster and reactivity at its surface. It is found that functionalization is preferred over reconstruction at the (100) surface and promotes graphitization in the (111) surface for NDs functionalized with the carbonyl oxygen (C = O) group. It is also seen that the edges of ND are the preferred sites for functionalization with the carboxyl group (-COOH) vis-a-vis the corners of ND.

  7. Trends in the chemical properties in early transition metal carbide surfaces: A density functional study

    DEFF Research Database (Denmark)

    Kitchin, J.R.; Nørskov, Jens Kehlet; Barteau, M.A.

    2005-01-01

    In this paper we present density functional theory (DFT) investigations of the physical, chemical and electronic structure properties of several close-packed surfaces of early transition metal carbides, including beta-Mo2C(0 0 0 1), and the (1 1 1) surfaces of TiC, VC, NbC, and TaC. The results...... are in excellent agreement with experimental values of lattice constants and bulk moduli. The adsorption of atomic hydrogen is used as a probe to compare the chemical properties of various carbide surfaces. Hydrogen adsorbs more strongly to the metal-terminated carbide surfaces than to the corresponding closest......-packed pure metal surfaces, due to the tensile strain induced in the carbide surfaces upon incorporation of carbon into the lattice. Hydrogen atoms were found to adsorb more weakly on carbide surfaces than on the corresponding closest-packed pure metal surfaces only when there were surface carbon atoms...

  8. Highly sensitive BTX detection using surface functionalized QCM sensor

    Energy Technology Data Exchange (ETDEWEB)

    Bozkurt, Asuman Aşıkoğlu; Özdemir, Okan; Altındal, Ahmet, E-mail: altindal@yildiz.edu.tr [Department of Physics, Yildiz Technical University, Davutpasa, 34210 Istanbul (Turkey)

    2016-03-25

    A novel organic compound was designed and successfully synthesized for the fabrication of QCM based sensors to detect the low concentrations of BTX gases in indoor air. The effect of the long-range electron orbital delocalization on the BTX vapour sensing properties of azo-bridged Pcs based chemiresistor-type sensors have also been investigated in this work. The sensing behaviour of the film for the online detection of volatile organic solvent vapors was investigated by utilizing an AT-cut quartz crystal resonator. It was observed that the adsorption of the target molecules on the coating surface cause a reversible negative frequency shift of the resonator. Thus, a variety of solvent vapors can be detected by using the phthalocyanine film as sensitive coating, with sensitivity in the ppm range and response times in the order of several seconds depending on the molecular structure of the organic solvent.

  9. Placental Plasmodium falciparum malaria infection: Operational accuracy of HRP2 rapid diagnostic tests in a malaria endemic setting

    Directory of Open Access Journals (Sweden)

    Montague Mark

    2011-10-01

    Full Text Available Abstract Background Malaria has a negative effect on the outcome of pregnancy. Pregnant women are at high risk of severe malaria and severe haemolytic anaemia, which contribute 60-70% of foetal and perinatal losses. Peripheral blood smear microscopy under-estimates sequestered placental infections, therefore malaria rapid diagnostic tests (RDTs detecting histidine rich protein-2 antigen (HRP-2 in peripheral blood are a potential alternative. Methods HRP-2 RDTs accuracy in detecting malaria in pregnancy (MIP >28 weeks gestation and placental Plasmodium falciparum malaria (after childbirth were conducted using Giemsa microscopy and placental histopathology respectively as the reference standard. The study was conducted in Mbale Hospital, using the midwives to perform and interpret the RDT results. Discordant results samples were spot checked using PCR techniques. Results Among 433 febrile women tested, RDTs had a sensitivity of 96.8% (95% CI 92-98.8, specificity of 73.5% (95% CI 67.8-78.6, a positive predictive value (PPV of 68.0% (95% CI 61.4-73.9, and negative predictive value (NPV of 97.5% (95% CI 94.0-99.0 in detecting peripheral P. falciparum malaria during pregnancy. At delivery, in non-symptomatic women, RDTs had a 80.9% sensitivity (95% CI 57.4-93.7 and a 87.5% specificity (95%CI 80.9-92.1, PPV of 47.2% (95% CI 30.7-64.2 and NPV of 97.1% (95% CI 92.2-99.1 in detecting placental P. falciparum infections among 173 samples. At delivery, 41% of peripheral infections were detected by microscopy without concurrent placental infection. The combination of RDTs and microscopy improved the sensitivity to 90.5% and the specificity to 98.4% for detecting placental malaria infection (McNemar's X 2> 3.84. RDTs were not superior to microscopy in detecting placental infection (McNemar's X 2 Conclusion Use of HRP-2 RDTs to detect malaria in pregnancy in symptomatic women was accurate when performed by midwives. A combination of RDTs and microscopy provided

  10. Density-functional calculation of van der Waals forces for free-electron-like surfaces

    DEFF Research Database (Denmark)

    Hult, E.; Hyldgaard, P.; Rossmeisl, Jan

    2001-01-01

    A recently proposed general density functional for asymptotic van der Waals forces is used to calculate van der Waals coefficients and reference-plane positions for realistic low-indexed Al surfaces. Results are given for a number of atoms and molecules outside the surfaces, as well as for the in......A recently proposed general density functional for asymptotic van der Waals forces is used to calculate van der Waals coefficients and reference-plane positions for realistic low-indexed Al surfaces. Results are given for a number of atoms and molecules outside the surfaces, as well...... as for the interaction between the surfaces themselves. The densities and static image-plane positions that are needed as input in the van der Waals functional are calculated self-consistently within density-functional theory using the generalized-gradient approximation, pseudopotentials, and plane waves. This study...

  11. Osteoblast response to the surface of amino acid-functionalized hydroxyapatite.

    Science.gov (United States)

    Lee, Wing-Hin; Loo, Ching-Yee; Chrzanowski, Wojciech; Rohanizadeh, Ramin

    2015-06-01

    Interactions between proteins and the surface of biomaterials are crucial for the biological function and success of materials implanted in the human body. In this study, hydroxyapatite (HA) with negative and positive surface charges were fabricated by functionalizing the HA surface with acidic or basic amino acids. The influence of HA surface charge on protein adsorption and cell activities was studied. The crystallinity, morphology, and surface charge of amino acid-functionalized HA (AA-HA) particles and the stability of amino acids on the HA surface were determined. Both AA-HA and unmodified HA were studied for their capacity to adsorb proteins present in biological medium. The results showed that the presence of glutamic acid; Glu (acidic amino acids) and arginine; Arg (basic amino acids) on the HA surface resulted in higher protein adsorption owing to stronger electrostatic attraction between the HA particles and the proteins in medium. Functionalizing HA with Glu and Arg significantly promoted osteoblast adhesion on the surface of treated HA. No significant differences in cell proliferation between negatively and positively charged HA was observed. Significantly higher alkaline phosphatase (ALP) activity of osteoblasts on both charged surfaces was seen as compared to the unmodified HA. The study demonstrated that immobilization of amino acids (Glu and Arg) on the surface of HA promoted osteoblast proliferation and ALP activity. © 2014 Wiley Periodicals, Inc.

  12. Electric fields control the orientation of peptides irreversibly immobilized on radical-functionalized surfaces.

    Science.gov (United States)

    Martin, Lewis J; Akhavan, Behnam; Bilek, Marcela M M

    2018-01-24

    Surface functionalization of an implantable device with bioactive molecules can overcome adverse biological responses by promoting specific local tissue integration. Bioactive peptides have advantages over larger protein molecules due to their robustness and sterilizability. Their relatively small size presents opportunities to control the peptide orientation on approach to a surface to achieve favourable presentation of bioactive motifs. Here we demonstrate control of the orientation of surface-bound peptides by tuning electric fields at the surface during immobilization. Guided by computational simulations, a peptide with a linear conformation in solution is designed. Electric fields are used to control the peptide approach towards a radical-functionalized surface. Spontaneous, irreversible immobilization is achieved when the peptide makes contact with the surface. Our findings show that control of both peptide orientation and surface concentration is achieved simply by varying the solution pH or by applying an electric field as delivered by a small battery.

  13. Towards modelling the vibrational signatures of functionalized surfaces: carboxylic acids on H-Si(111) surfaces

    Science.gov (United States)

    Giresse Tetsassi Feugmo, Conrard; Champagne, Benoît; Caudano, Yves; Cecchet, Francesca; Chabal, Yves J.; Liégeois, Vincent

    2012-03-01

    In this work, we investigate the adsorption process of two carboxylic acids (stearic and undecylenic) on a H-Si(111) surface via the calculation of structural and energy changes as well as the simulation of their IR and Raman spectra. The two molecules adsorb differently at the surface since the stearic acid simply physisorbs while the undecylenic acid undergoes a chemical reaction with the hydrogen atoms of the surface. This difference is observed in the change of geometry during the adsorption. Indeed, the chemisorption of the undecylenic acid has a bigger impact on the structure than the physisorption of the stearic acid. Consistently, the former is also characterized by a larger value of adsorption energy and a smaller value of the tilting angle with respect to the normal plane. For both the IR and Raman signatures, the spectra of both molecules adsorbed at the surface are in a first approximation the superposition of the spectra of the Si cluster and of the carboxylic acid considered individually. The main deviation from this simple observation is the peak of the stretching Si-H (ν(Si-H)) mode, which is split into two peaks upon adsorption. As expected, the splitting is bigger for the chemisorption than the physisorption. The modes corresponding to atomic displacements close to the adsorption site display a frequency upshift by a dozen wavenumbers. One can also see the disappearance of the peaks associated with the C=C double bond when the undecylenic acid chemisorbs at the surface. The Raman and IR spectra are complementary and one can observe here that the most active Raman modes are generally IR inactive. Two exceptions to this are the two ν(Si-H) modes which are active in both spectroscopies. Finally, we compare our simulated spectra with some experimental measurements and we find an overall good agreement.

  14. Towards modelling the vibrational signatures of functionalized surfaces: carboxylic acids on H-Si(111) surfaces

    International Nuclear Information System (INIS)

    Tetsassi Feugmo, Conrard Giresse; Champagne, Benoît; Liégeois, Vincent; Caudano, Yves; Cecchet, Francesca; Chabal, Yves J

    2012-01-01

    In this work, we investigate the adsorption process of two carboxylic acids (stearic and undecylenic) on a H-Si(111) surface via the calculation of structural and energy changes as well as the simulation of their IR and Raman spectra. The two molecules adsorb differently at the surface since the stearic acid simply physisorbs while the undecylenic acid undergoes a chemical reaction with the hydrogen atoms of the surface. This difference is observed in the change of geometry during the adsorption. Indeed, the chemisorption of the undecylenic acid has a bigger impact on the structure than the physisorption of the stearic acid. Consistently, the former is also characterized by a larger value of adsorption energy and a smaller value of the tilting angle with respect to the normal plane. For both the IR and Raman signatures, the spectra of both molecules adsorbed at the surface are in a first approximation the superposition of the spectra of the Si cluster and of the carboxylic acid considered individually. The main deviation from this simple observation is the peak of the stretching Si-H (ν(Si-H)) mode, which is split into two peaks upon adsorption. As expected, the splitting is bigger for the chemisorption than the physisorption. The modes corresponding to atomic displacements close to the adsorption site display a frequency upshift by a dozen wavenumbers. One can also see the disappearance of the peaks associated with the C=C double bond when the undecylenic acid chemisorbs at the surface. The Raman and IR spectra are complementary and one can observe here that the most active Raman modes are generally IR inactive. Two exceptions to this are the two ν(Si-H) modes which are active in both spectroscopies. Finally, we compare our simulated spectra with some experimental measurements and we find an overall good agreement. (paper)

  15. Using the lambda function to evaluate probe measurements of charged dielectric surfaces

    DEFF Research Database (Denmark)

    Rerup, T. O.; Crichton, George C; McAllister, Iain Wilson

    1996-01-01

    The use of Pedersen's λ function to evaluate electrostatic probe measurements of charged dielectric surfaces is demonstrated. With a knowledge of the probe λ function, the procedure by which this function is employed is developed, and thereafter applied to a set of experimental measurements avail...

  16. Functionality of porous silicon particles: Surface modification for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Gallach, D.; Recio Sanchez, G.; Munoz Noval, A. [Departamento de Fisica Aplicada y Departamento de Biologia Molecular, Facultad de Ciencias, Cantoblanco, 28049 Madrid (Spain); Centro de Investigaciones Biomedicas en Red, Biomateriales, Bioingenieria y Nanomedicina (CIBERbbn) (Spain); Manso Silvan, M., E-mail: miguel.manso@uam.es [Departamento de Fisica Aplicada y Departamento de Biologia Molecular, Facultad de Ciencias, Cantoblanco, 28049 Madrid (Spain); Centro de Investigaciones Biomedicas en Red, Biomateriales, Bioingenieria y Nanomedicina (CIBERbbn) (Spain); Ceccone, G. [Institute for Health and Consumer Protection, European Commission, 21020 Ispra (Italy); Martin Palma, R.J.; Torres Costa, V.; Martinez Duart, J.M. [Departamento de Fisica Aplicada y Departamento de Biologia Molecular, Facultad de Ciencias, Cantoblanco, 28049 Madrid (Spain); Centro de Investigaciones Biomedicas en Red, Biomateriales, Bioingenieria y Nanomedicina (CIBERbbn) (Spain)

    2010-05-25

    Porous silicon-based particles (PSps) with tailored physical and biological properties have recently attracted great attention given their biomedical potential. Within this context, the objective of the present work is to optimize the experimental parameters for the formation of biofunctional mesoporous PSps. Their functionality has been studied on the one hand by analyzing the fluorescence characteristics, such as tunable narrow band emission and fluorescence aging for PSps with different molecular capping. With regard to the biofunctional characteristics, two different molecular end-capping processes have been assayed: antifouling polyethylene glycol (PEG) and polar binding amino silanes (APTS), which were evaluated by X-ray photoelectron spectroscopy (XPS). Both PEG and APTS binding to the particles could be confirmed from the analysis of Si 2p and C 1s XPS core level spectra. The finding that these PSp-molecule conjugates allow the reduction of fluorescence degradation with time in solution is of interest for the development of cellular or tissue markers. From the morphological point of view, PEG termination is of special interest allowing the PSps after an ultrasonic treatment to get spherical shapes in the micron scale. The functionality as solid state dyes is preliminarily evaluated by direct fluorescence imaging.

  17. Functionality of porous silicon particles: Surface modification for biomedical applications

    International Nuclear Information System (INIS)

    Gallach, D.; Recio Sanchez, G.; Munoz Noval, A.; Manso Silvan, M.; Ceccone, G.; Martin Palma, R.J.; Torres Costa, V.; Martinez Duart, J.M.

    2010-01-01

    Porous silicon-based particles (PSps) with tailored physical and biological properties have recently attracted great attention given their biomedical potential. Within this context, the objective of the present work is to optimize the experimental parameters for the formation of biofunctional mesoporous PSps. Their functionality has been studied on the one hand by analyzing the fluorescence characteristics, such as tunable narrow band emission and fluorescence aging for PSps with different molecular capping. With regard to the biofunctional characteristics, two different molecular end-capping processes have been assayed: antifouling polyethylene glycol (PEG) and polar binding amino silanes (APTS), which were evaluated by X-ray photoelectron spectroscopy (XPS). Both PEG and APTS binding to the particles could be confirmed from the analysis of Si 2p and C 1s XPS core level spectra. The finding that these PSp-molecule conjugates allow the reduction of fluorescence degradation with time in solution is of interest for the development of cellular or tissue markers. From the morphological point of view, PEG termination is of special interest allowing the PSps after an ultrasonic treatment to get spherical shapes in the micron scale. The functionality as solid state dyes is preliminarily evaluated by direct fluorescence imaging.

  18. Surface functionalization of titanium substrates with chitosan-lauric acid conjugate to enhance osteoblasts functions and inhibit bacteria adhesion.

    Science.gov (United States)

    Zhao, Lu; Hu, Yan; Xu, Dawei; Cai, Kaiyong

    2014-07-01

    Orthopedic implants failures are generally related to poor osseointegration and/or bacterial infection in clinical application. Surface functionalization of an implant is one promising alternative for enhancing osseointegration and/or reducing bacterial infection, thus ensuring the long term survival of the implant. In this study, titanium (Ti) substrates were surface functionalized with a polydopamine (PDOP) film as an intermediate layer for post-immobilization of chitosan-lauric acid (Chi-LA) conjugate. Chi-LA conjugate was synthesized and characterized by Fourier transform infrared spectroscopy (FTIR) and hydrogen proton nuclear magnetic resonance (NMR) spectrometer, respectively. Lauric acid (LA), a natural saturated fatty acid, was used mainly due to its good antibacterial property. Scanning electron microscopy (SEM) and water contact angle measurements were employed to detect the morphology changes and surface wettability of Ti substrates. The results suggested that Chi-LA conjugate was successfully immobilized onto the surfaces of Ti substrates. In vitro tests confirmed that the cell adhesion, cell viability, intracellular alkaline phosphatase activity and mineralization capacity of osteoblasts were remarkably improved when cultured onto Chi-LA surface functionalized Ti substrates. Antibacterial assay against Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) showed that the Chi-LA modified Ti substrates efficiently inhibited the adhesion and growth of bacteria. Overall, this study developed a promising approach to fabricate functional Ti-based orthopedic implants, which could enhance the biological functions of osteoblasts and concurrently reduce bacteria adhesion. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Effect of titanium surface characteristics on the behavior and function of oral fibroblasts.

    Science.gov (United States)

    Att, Wael; Yamada, Masahiro; Ogawa, Takahiro

    2009-01-01

    The purpose of this study was to evaluate the effect of different titanium surface characteristics on the behavior and function of oral fibroblasts as well as the deposition pattern of collagen within the extracellular matrix. Titanium surfaces created by machining, acid etching with sulfuric acid (AE1), or acid etching with hydrofluoric acid (AE2) were analyzed using scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy. Rat oral fibroblasts were cultured on different surfaces. Cell spread and morphology of extracellular matrix were evaluated using SEM. Attachment and proliferation of cells were examined by comparing the numbers of attached to detached cells and cell count, respectively. Gene expression was analyzed via reverse transcriptase polymerase chain reaction. Collagen production and deposition were examined via a Sirius red-based stain assay and confocal laser scanning microscopy. The machined surface showed a flat profile with isotropic grooves, the AE1 surface showed a uniformly microscale roughened surface, and the AE2 surface had a grooved profile with intermediate surface roughness. The AE2 surface contained fluoride atoms (2.45%+/-0.44% as F/Ti atomic ratio). Cell attachment was significantly weaker on the machined surface than on the AE1 and AE2 surfaces, whereas no differences were observed between the AE1 and AE2 surfaces. The cell counts on the machined and AE2 surfaces were higher, with a parallel orientation, whereas the cell count was lower and randomly distributed on the AE1 surface. The expression level of fibroblastic genes was similar among surfaces for all time points tested. Collagen production was highest on the machined surface, followed by AE2 and AE1 surfaces. Collagen deposition displayed a parallel pattern on the machined surface, while it was multidirectional on the AE1 and AE2 surfaces. The surface characteristics of titanium affect attachment, spread, and proliferative activity of oral fibroblasts as well

  20. Grafting of phosphorylcholine functional groups on polycarbonate urethane surface for resisting platelet adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Bin [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Feng, Yakai, E-mail: yakaifeng@hotmail.com [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Tianjin University-Helmholtz-Zentrum Geesthacht, Joint Laboratory for Biomaterials and Regenerative Medicine, Weijin Road 92, 300072 Tianjin (China); Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Lu, Jian; Zhang, Li; Zhao, Miao; Shi, Changcan; Khan, Musammir [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Guo, Jintang [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Tianjin University-Helmholtz-Zentrum Geesthacht, Joint Laboratory for Biomaterials and Regenerative Medicine, Weijin Road 92, 300072 Tianjin (China)

    2013-07-01

    In order to improve the resistance of platelet adhesion on material surface, 2-methacryloyloxyethyl phosphorylcholine (MPC) was grafted onto polycarbonate urethane (PCU) surface via Michael reaction to create biomimetic structure. After introducing primary amine groups via coupling tris(2-aminoethyl)amine (TAEA) onto the polymer surface, the double bond of MPC reacted with the amino group to obtain MPC modified PCU. The modified surface was characterized by Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The results verified that MPC was grafted onto PCU surface by Michael reaction method. The MPC grafted PCU surface had a low water contact angle and a high water uptake. This means that the hydrophilic PC functional groups improved the surface hydrophilicity significantly. In addition, surface morphology of MPC grafted PCU film was imaged by atomic force microscope (AFM). The results showed that the grafted surface was rougher than the blank PCU surface. In addition, platelet adhesion study was evaluated by scanning electron microscopy (SEM) observation. The PCU films after treated with platelet-rich plasma demonstrated that much fewer platelets adhered to the MPC-grafted PCU surface than to the blank PCU surface. The antithrombogenicity of the MPC-grafted PCU surface was determined by the activated partial thromboplastin time (APTT). The result suggested that the MPC modified PCU may have potential application as biomaterials in blood-contacting and some subcutaneously implanted devices. - Highlights: • MPC was successfully grafted onto polycarbonate urethane surface via Michael reaction. • High concentration of PC functional groups on the surface via TAEA molecule • Biomimetic surface modification • The modified surface showed high hydrophilicity and anti-platelet adhesion.

  1. Surface enhanced infrared absorption spectroscopy for graphene functionalization on copper

    Czech Academy of Sciences Publication Activity Database

    Matulková, I.; Kovaříček, Petr; Šlouf, Miroslav; Němec, I.; Kalbáč, Martin

    2017-01-01

    Roč. 124, NOV 2017 (2017), s. 250-255 ISSN 0008-6223 R&D Projects: GA ČR(CZ) GA15-01953S; GA MŠk LL1301; GA MŠk(CZ) LM2015073 Grant - others:AVČR PPPLZ(CZ) L200401551; GA MŠk(CZ) CZ.02.1.01/0.0/0.0/16_013/0001821 Institutional support: RVO:61388955 ; RVO:61389013 Keywords : chemical-vapor-deposition * diazonium salts * raman-spectroscopy * covalent functionalization * seira spectroscopy * grown graphene Subject RIV: CF - Physical ; Theoretical Chemistry; CD - Macromolecular Chemistry (UMCH-V) OBOR OECD: Physical chemistry; Polymer science (UMCH-V) Impact factor: 6.337, year: 2016

  2. Surface enhanced infrared absorption spectroscopy for graphene functionalization on copper

    Czech Academy of Sciences Publication Activity Database

    Matulková, I.; Kovaříček, Petr; Šlouf, Miroslav; Němec, I.; Kalbáč, Martin

    2017-01-01

    Roč. 124, NOV 2017 (2017), s. 250-255 ISSN 0008-6223 R&D Projects: GA ČR(CZ) GA15-01953S; GA MŠk LL1301; GA MŠk(CZ) LM2015073 Grant - others:AVČR PPPLZ(CZ) L200401551; GA MŠk(CZ) CZ.02.1.01/0.0/0.0/16_013/0001821 Institutional support: RVO:61388955 ; RVO:61389013 Keywords : chemical -vapor-deposition * diazonium salts * raman-spectroscopy * covalent functionalization * seira spectroscopy * grown graphene Subject RIV: CF - Physical ; Theoretical Chemistry; CD - Macromolecular Chemistry (UMCH-V) OBOR OECD: Physical chemistry; Polymer science (UMCH-V) Impact factor: 6.337, year: 2016

  3. Common fur and mystacial vibrissae parallel sensory pathways: 14C 2-deoxyglucose and WGA-HRP studies in the rat

    International Nuclear Information System (INIS)

    Sharp, F.R.; Gonzalez, M.F.; Morgan, C.W.; Morton, M.T.; Sharp, J.W.

    1988-01-01

    Stimulation of mystacial vibrissae in rows A,B, and C increased (14C) 2-deoxyglucose (2DG) uptake in spinal trigeminal nucleus pars caudalis (Sp5c) mostly in ventral portions of laminae III-IV with less activation of II and V. Stimulation of common fur above the whiskers mainly activated lamina II, with less activation in deeper layers. The patterns of activation were compatible with an inverted head, onion skin Sp5c somatotopy. Wheatgerm Agglutinin-Horseradish Peroxidase (WGA-HRP) injections into common fur between mystacial vibrissae rows A-B and B-C led to anterograde transganglionic labeling only of Sp5c, mainly of lamina II with less label in layer V, and very sparse label in III and IV. WGA-HRP skin injections appear to primarily label small fibers, which along with larger fibers, were metabolically activated during common fur stimulation. Mystacial vibrissae stimulation increased 2DG uptake in ventral ipsilateral spinal trigeminal nuclei pars interpolaris (Sp5i) and oralis (Sp5o) and principal trigeminal sensory nucleus (Pr5). Common fur stimulation above the whiskers slightly increased 2DG uptake in ventral Sp5i, Sp5o, and possibly Pr5. The most dorsal aspect of the ventroposteromedial (VPM) nucleus of thalamus was activated contralateral to whisker stimulation. Stimulation of the common fur dorsal to the whiskers activated a region of dorsal VPM caudal to the VPM region activated during whisker stimulation. This is consistent with previous data showing that ventral whiskers and portions of the face are represented rostrally in VPM, and more dorsal whiskers and dorsal portions of the face are represented progressively more caudally in VPM. Mystacial vibrissae stimulation activated the contralateral primary sensory SI barrelfield cortex and a separate region in the second somatosensory SII cortex

  4. Preparation and biocompatibility of grafted functional β-cyclodextrin copolymers from the surface of PET films

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Yan, E-mail: yan_jiang_72@126.com [College of Materials Science and Engineering, Changzhou University, Changzhou 213164, Jiangsu (China); Liang, Yuan; Zhang, Hongwen [College of Materials Science and Engineering, Changzhou University, Changzhou 213164, Jiangsu (China); Zhang, Weiwei [College of Life Science, Agriculture and Forestry, Qiqihar University, Qiqihar 161006, Heilongjiang (China); Tu, Shanshan [College of Materials Science and Engineering, Changzhou University, Changzhou 213164, Jiangsu (China)

    2014-08-01

    The hydrophobic inert surface of poly(ethylene terephthalate) (PET) film has limited its practical bioapplications, in which case, better biocompatibility should be achieved by surface modification. In this work, the copolymer of functional β-cyclodextrin derivatives and styrene grafted surfaces was prepared via surface-initiated atom transfer radical polymerization (SI-ATRP) on initiator-immobilized PET. The structures, composition, properties, and surface morphology of the modified PET films were characterized by fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), contact angle measurement, and scanning electronic microscopy (SEM). The results show that the surface of PET films was covered by a thick targeted copolymer layer, and the hydrophobic surface of PET was changed into an amphiphilic surface. The copolymer-grafted surfaces were also shown good biocompatibility on which SGC-7901 A549 and A549/DDP cells readily attached and proliferated, demonstrating that the functional copolymer-grafted PET films could be a promising alternative to biomaterials especially for tissue engineering. - Highlights: • The PET film was grafted by functional β-CD copolymers, which owns amphiphilicity. • The surface of grafted PET film by copolymers enhanced the cell adhesion and growth. • The biocompatible PET film may be used in tissue engineering and cell cultivation.

  5. A two-genome microarray for the rice pathogens Xanthomonas oryzae pv. oryzae and X. oryzae pv. oryzicola and its use in the discovery of a difference in their regulation of hrp genes

    Directory of Open Access Journals (Sweden)

    Lin Ye

    2008-06-01

    Full Text Available Abstract Background Xanthomonas oryzae pv. oryzae (Xoo and X. oryzae pv. oryzicola (Xoc are bacterial pathogens of the worldwide staple and grass model, rice. Xoo and Xoc are closely related but Xoo invades rice vascular tissue to cause bacterial leaf blight, a serious disease of rice in many parts of the world, and Xoc colonizes the mesophyll parenchyma to cause bacterial leaf streak, a disease of emerging importance. Both pathogens depend on hrp genes for type III secretion to infect their host. We constructed a 50–70 mer oligonucleotide microarray based on available genome data for Xoo and Xoc and compared gene expression in Xoo strains PXO99A and Xoc strain BLS256 grown in the rich medium PSB vs. XOM2, a minimal medium previously reported to induce hrp genes in Xoo strain T7174. Results Three biological replicates of the microarray experiment to compare global gene expression in representative strains of Xoo and Xoc grown in PSB vs. XOM2 were carried out. The non-specific error rate and the correlation coefficients across biological replicates and among duplicate spots revealed that the microarray data were robust. 247 genes of Xoo and 39 genes of Xoc were differentially expressed in the two media with a false discovery rate of 5% and with a minimum fold-change of 1.75. Semi-quantitative-RT-PCR assays confirmed differential expression of each of 16 genes each for Xoo and Xoc selected for validation. The differentially expressed genes represent 17 functional categories. Conclusion We describe here the construction and validation of a two-genome microarray for the two pathovars of X. oryzae. Microarray analysis revealed that using representative strains, a greater number of Xoo genes than Xoc genes are differentially expressed in XOM2 relative to PSB, and that these include hrp genes and other genes important in interactions with rice. An exception was the rax genes, which are required for production of the host resistance elicitor AvrXa21

  6. Genetic variation of pfhrp2 in Plasmodium falciparum isolates from Yemen and the performance of HRP2-based malaria rapid diagnostic test.

    Science.gov (United States)

    Atroosh, Wahib M; Al-Mekhlafi, Hesham M; Al-Jasari, Adel; Sady, Hany; Al-Delaimy, Ahmed K; Nasr, Nabil A; Dawaki, Salwa; Abdulsalam, Awatif M; Ithoi, Init; Lau, Yee Ling; Fong, Mun Yik; Surin, Johari

    2015-07-22

    The genetic variation in the Plasmodium falciparum histidine-rich protein 2 (pfhrp2) gene that may compromise the use of pfhrp2-based rapid diagnostic tests (RDTs) for the diagnosis of malaria was assessed in P. falciparum isolates from Yemen. This study was conducted in Hodeidah and Al-Mahwit governorates, Yemen. A total of 622 individuals with fever were examined for malaria by CareStart malaria HRP2-RDT and Giemsa-stained thin and thick blood films. The Pfhrp2 gene was amplified and sequenced from 180 isolates, and subjected to amino acid repeat types analysis. A total of 188 (30.2%) participants were found positive for P. falciparum by the RDT. Overall, 12 different amino acid repeat types were identified in Yemeni isolates. Six repeat types were detected in all the isolates (100%) namely types 1, 2, 6, 7, 10 and 12 while types 9 and 11 were not detected in any of the isolates. Moreover, the sensitivity and specificity of the used PfHRP2-based RDTs were high (90.5% and 96.1%, respectively). The present study provides data on the genetic variation within the pfhrp2 gene, and its potential impact on the PfHRP2-based RDTs commonly used in Yemen. CareStart Malaria HRP2-based RDT showed high sensitivity and specificity in endemic areas of Yemen.

  7. Exploring health practitioners' acceptability of a prospective semi-quantitative pfHRP2 device to define severe malaria in the Democratic Republic of Congo

    NARCIS (Netherlands)

    De Haan, Freek; Onyamboko, Marie A.; Fanello, Caterina I.; Woodrow, Charles J.; Lubell, Yoel; Boon, Wouter P. C.; Dondorp, Arjen M.

    2015-01-01

    Background: A rapid diagnostic tool is being developed to discern severely ill children with severe malaria from children who are ill with alternative febrile diseases but have coincidental peripheral blood parasitaemia. The device semi-quantitatively measures plasma pfHRP2 and has the potential to

  8. The Effect of Surface Functionalization on the Immobilization of Gold Nanoparticles on Graphene Sheets

    OpenAIRE

    Song, Min; Xu, Juan; Wu, Changzi

    2012-01-01

    In our study, graphene oxide is synthesized by Hummers method. And then, carboxylic acid functionalized graphene (graphene-COOH), thiol-functionalized graphene (graphene-SH), and highly dispersive graphene are prepared by chemical modification of respective groups on the graphene surface. Furthermore, we explore a solution-based approach to prepare three differently functionalized graphene-gold composites by one-step chemical reduction of AuCl4 - ions in respective functionalized graphene sus...

  9. Surface Acoustic Wave (SAW-Enhanced Chemical Functionalization of Gold Films

    Directory of Open Access Journals (Sweden)

    Gina Greco

    2017-10-01

    Full Text Available Surface chemical and biochemical functionalization is a fundamental process that is widely applied in many fields to add new functions, features, or capabilities to a material’s surface. Here, we demonstrate that surface acoustic waves (SAWs can enhance the chemical functionalization of gold films. This is shown by using an integrated biochip composed by a microfluidic channel coupled to a surface plasmon resonance (SPR readout system and by monitoring the adhesion of biotin-thiol on the gold SPR areas in different conditions. In the case of SAW-induced streaming, the functionalization efficiency is improved ≈ 5 times with respect to the case without SAWs. The technology here proposed can be easily applied to a wide variety of biological systems (e.g., proteins, nucleic acids and devices (e.g., sensors, devices for cell cultures.

  10. Neuromuscular functions in sportsmen and fibromyalgia patients : a surface EMG study in static and dynamic conditions

    NARCIS (Netherlands)

    Klaver-Krol, E.G.

    2012-01-01

    This thesis presents two studies, one involving sportsmen (sprinters versus endurance athletes) and one fibromyalgia patients (patients versus healthy controls). The studies have investigated muscular functions using a non-invasive method: surface electromyography (sEMG). In the sportsmen,

  11. Orientations of Liquid Crystals in Contact with Surfaces that Present Continuous Gradients of Chemical Functionality

    International Nuclear Information System (INIS)

    Clare, B.; Efimenko, K.; Fischer, D.; Genzer, J.; Abbott, N.

    2006-01-01

    We report the formation of continuous spatial gradients in the density of grafted semifluorinated chains on silicon oxide surfaces by vapor-phase diffusion of semifluorinated silanes. We quantify the orientations of the nematic liquid crystal (LC) 4-cyano-4'-pentylbiphenyl on these surfaces as a function of local surface composition obtained by using NEXAFS. These measurements demonstrate that it is possible to obtain the full range of tilt angles of a LC on these surfaces. We also use the data provided by these gradient surfaces to test hypotheses regarding the nature of the interaction between the LC and surfaces that give rise to the range of tilted orientations of the LC. We conclude that the orientations of the LC are not determined solely by the density of grafted semifluorinated chains or by the density of residual hydroxyl groups presented at these surfaces following reactions with the silanes. Instead, our results raise the possibility that the tilt angles of the semifluorinated chains on these surfaces (which are a function of the density of the grafted chains) may influence the orientation of the LC. These results, when combined, demonstrate the potential utility of gradient surfaces for screening surface chemistries that achieve desired orientations of LCs as well as for rapidly assembling experimental data sets that can be used to test propositions regarding mechanisms of anchoring LCs at surfaces

  12. Physicochemical properties of functional surfaces in pitchers of the carnivorous plant Nepenthes alata Blanco (Nepenthaceae).

    Science.gov (United States)

    Gorb, E V; Gorb, S N

    2006-11-01

    Pitchers of the carnivorous plant Nepenthes alata are highly specialized organs adapted to attract, capture, and digest animals, mostly insects. They consist of several well distinguishable zones, differing in macro-morphology, surface microstructure, and functions. Since physicochemical properties of these surfaces may influence insect adhesion, we measured contact angles of non-polar (diiodomethane) and polar liquids (water and ethylene glycol) and estimated the free surface energy of 1) the lid, 2) the peristome, 3) the waxy surface of the slippery zone, and 4) the glandular surface of the digestive zone in N. alata pitchers. As a control, the external surface of the pitcher, as well as abaxial and adaxial surfaces of the leaf blade, was measured. Both leaf surfaces, both lid surfaces, and the external pitcher surface showed similar contact angles and had rather high values of surface free energy with relatively high dispersion component. These surfaces are considered to support strong adhesion forces based on the capillary interaction, and by this, to promote successful attachment of insects. The waxy surface is almost unwettable, has extremely low surface energy, and therefore, must essentially decrease insect adhesion. Both the peristome and glandular surfaces are wetted readily with both non-polar and polar liquids and have very high surface energy with a predominating polar component. These properties result in the preclusion of insect adhesion due to the hydrophilic lubricating film covering the surfaces. The obtained results support field observations and laboratory experiments of previous authors that demonstrated the possible role of different pitcher surfaces in insect trapping and retention.

  13. Poly-lactic-glycolic-acid surface nanotopographies selectively decrease breast adenocarcinoma cell functions

    Science.gov (United States)

    Zhang, Lijuan; Webster, Thomas J.

    2012-04-01

    The ability of poly(lactic-co-glycolic acid) (PLGA, 50:50 PLG/PGA, wt%) nanotopographies to decrease lung epithelial carcinoma cell functions (including adhesion, proliferation, apoptosis and vascular endothelial growth factor (VEGF) secretion) has been previously reported. Specifically, results demonstrated decreased lung epithelial carcinoma cell VEGF synthesis on 23 nm surface-featured PLGA compared to traditional nanosmooth PLGA. However, clearly, different cell lines could have different behaviors on similar biomaterials. Thus, to investigate the universality of nanopatterned PLGA substrates to inhibit numerous cancer cell functions, here, breast epithelial adenocarcinoma cell (MCF-7) adhesion, proliferation, apoptosis and VEGF secretion were determined on different PLGA nanometer surface topographies. To isolate surface nanotopographical effects from all other surface properties, PLGA surfaces with various nanotopographies but similar chemistry and hydrophobicity were fabricated here. Atomic force microscopy (AFM) verified the varied nanotopographies on the PLGA surfaces prepared in this study. Importantly, results demonstrated for the first time significantly decreased breast adenocarcinoma cell functions (including decreased proliferation rate, increased apoptosis and decreased VEGF synthesis) on 23 nm featured PLGA surfaces compared to all other PLGA surface topographies fabricated (specifically, nanosmooth, 300 and 400 nm surface-featured PLGA surfaces). In contrast, healthy breast epithelial cells proliferated more (24%) on the 23 nm featured PLGA surfaces compared to all other PLGA samples. In summary, these results provided further insights into understanding the role PLGA surface nanotopographies can have on cancer cell functions and, more importantly, open the possibility of using polymer nanotopographies for a wide range of anticancer regenerative medicine applications (without resorting to the use of chemotherapeutics).

  14. Density-functional calculations of the surface tension of liquid Al and Na

    Science.gov (United States)

    Stroud, D.; Grimson, M. J.

    1984-01-01

    Calculations of the surface tensions of liquid Al and Na are described using the full ionic density functional formalism of Wood and Stroud (1983). Surface tensions are in good agreement with experiment in both cases, with results substantially better for Al than those found previously in the gradient approximation. Preliminary minimization with respect to surface profile leads to an oscillatory profile superimposed on a nearly steplike ionic density disribution; the oscillations have a wavellength of about a hardsphere diameter.

  15. Biomimetic Functionalized Surfaces and the Induction of Bone Formation.

    Science.gov (United States)

    Ripamonti, Ugo

    2017-11-01

    Tissue engineering still needs to assign the molecular basis of pattern formation, tissue induction, and morphogenesis: What next to morphogens and stem cells? Macroporous biomimetic matrices per se, without the addition of the soluble osteogenic molecular signals of the transforming growth factor-β (TGF-β) supergene family, remarkably initiate the induction of bone formation. Carving geometries within different calcium phosphate-based macroporous bioreactors we show that geometric cues imprinted within the macroporous spaces initiate the spontaneous induction of bone. Concavities biomimetize the remodeling cycle of the primate osteonic bone and are endowed with functionalized smart geometric cues that per se initiate osteoblasts' differentiation with the expression and secretion of osteogenic molecular signals that induce bone as a secondary response. To study the role of calcium ions (Ca ++ ) and osteoclastogenesis, coral-derived calcium carbonate (CC)/hydroxyapatite (HA) bioreactors with limited conversion to HA (7% HA/CC) were preloaded with 500 μg of the L-type voltage gated calcium channel blocker verapamil hydrochloride. Bioreactors were also loaded with 240 μg of the bisphosphonate zoledronate, an osteoclast inhibitor, and implanted in heterotopic sites of the rectus abdominis muscle of Papio ursinus. Bisphosphonate-treated specimens were characterized by a delayed profoundly inhibited induction of tissue patterning with limited induction of bone. Macroporous constructs pretreated with verapamil hydrochloride yielded limited bone formation. Similarly, 125 or 150 μg human Noggin previously adsorbed onto the macroporous bioreactors resulted in minimal bone formation by induction, indirectly showing that the initiation of bone formation is through the bone morphogenetic protein (BMP) pathway. Downregulation of BMP-2 and osteogenic protein-1 (OP-1) with upregulation of Noggin correlated with limited bone induction. Angiogenesis, capillary sprouting

  16. Electron work function and composition of gallium-indium alloy surface

    International Nuclear Information System (INIS)

    Egorova, E.M.

    1979-01-01

    The dependences of electron work functions on the composition for gallium-indium alloy obtained under different conditions are compared. An attempt is made to estimate a change in the alloy surface composition caused by a change in temperature and in the boundary phase nature. For the case under consideration it has been shown to be reasonable to compare the dependences of the electron work functions not on the alloy volumetric composition but on the composition of its surface

  17. In vitro characterization of bioactive titanium dioxide/hydroxyapatite surfaces functionalized with BMP-2.

    Science.gov (United States)

    Piskounova, Sonya; Forsgren, Johan; Brohede, Ulrika; Engqvist, Håkan; Strømme, Maria

    2009-11-01

    Poor implant fixation and bone resorption are two of the major challenges in modern orthopedics and are caused by poor bone/implant integration. In this work, bioactive crystalline titanium dioxide (TiO(2))/hydroxyapatite (HA) surfaces, functionalized with bone morphogenetic protein 2 (BMP-2), were evaluated as potential implant coatings for improved osseointegration. The outer layer consisted of HA, which is known to be osteoconductive, and may promote improved initial bone attachment when functionalized with active molecules such as BMP-2 in a soaking process. The inner layer of crystalline TiO(2) is bioactive and ensures long-term fixation of the implant, once the hydroxyapatite has been resorbed. The in vitro response of mesenchymal stem cells on bioactive crystalline TiO(2)/HA surfaces functionalized with BMP-2 was examined and compared with the cell behavior on nonfunctionalized HA layers, crystalline TiO(2) surfaces, and native titanium oxide surfaces. The crystalline TiO(2) and the HA surfaces showed to be more favorable than the native titanium oxide surface in terms of cell viability and cell morphology as well as initial cell differentiation. Furthermore, cell differentiation on BMP-2-functionalized HA surfaces was found to be significantly higher than on the other surfaces indicating that the simple soaking process can be used for incorporating active molecules, promoting fast bone osseointegration to HA layers.

  18. Ab initio and work function and surface energy anisotropy of LaB6

    NARCIS (Netherlands)

    Uijttewaal, M. A.; de Wijs, G. A.; de Groot, R. A.

    2006-01-01

    Lanthanum hexaboride is one of the cathode materials most used in high-power electronics technology, but the many experimental results do not provide a consistent picture of the surface properties. Therefore, we report the first ab initio calculations of the work functions and surface energies of

  19. Interrelation of work function and surface stability : The case of BaAl4

    NARCIS (Netherlands)

    Uijttewaal, MA; de Wijs, GA; de Groot, RA; Coehoorn, R; van Elsbergen, [No Value; Weijtens, CHL

    2005-01-01

    The relationship between the work function (Phi) and the surface stability of compounds is, to our knowledge, unknown but very important for applications such as organic light-emitting diodes. This relation is studied using first-principles calculations on various surfaces of BaAl4. The most stable

  20. Focal Adhesion of Osteoblastic Cells on Titanium Surface with Amine Functionalities Formed by Plasma Polymerization

    Science.gov (United States)

    Song, Heesang; Jung, Sang Chul; Kim, Byung Hoon

    2012-08-01

    To enhance the focal adhesion of osteoblastic cells on a titanium surface, plasma polymerized allyl amine (AAm) thin films were deposited by plasma polymerization. This plasma polymer functionalization of titanium is advantageous for osteoblastic focal adhesion formation. Such Ti surfaces are useful for the fabrication of titanium-based dental implants for enhancement of osseointegration.

  1. Grafting of functionalized polymer on porous silicon surface using Grignard reagent

    Science.gov (United States)

    Tighilt, F.-Z.; Belhousse, S.; Sam, S.; Hamdani, K.; Lasmi, K.; Chazalviel, J. N.; Gabouze, N.

    2017-11-01

    Recently, considerable attention has been paid to the manipulation and the control of the physicochemical properties of porous silicon surfaces because of their crucial importance to the modern microelectronics industry. Hybrid structures consisting of deposited polymer on porous silicon surfaces are important to applications in microelectronics, photovoltaics and sensors (Ensafi et al., 2016; Kashyout et al., 2015; Osorio et al.; 2015; Hejjo et al., 2002) [1-4]. In many cases, the polymer can provide excellent mechanical and chemical protection of the substrate, changes the electrochemical interface characteristics of the substrate, and provides new ways to the functionalization of porous silicon surfaces for molecular recognition and sensing. In this work, porous silicon surface was modified by anodic treatment in ethynylmagnesium bromide electrolyte leading to the formation of a polymeric layer bearing some bromine substituents. Subsequently, the formed polymer is functionalized with amine molecules containing functional groups (carboxylic acid or pyridine) by a substitution reaction between bromine sites and amine groups (Hofmann reaction). The chemical composition of the modified porous silicon surfaces was investigated and the grafting of polymeric chains and functional groups on the porous silicon surface was confirmed by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) which displayed the principal characteristic peaks attributed to the different functional groups. Furthermore, the surface of the material was examined by scanning electron microscopy (SEM).

  2. Surface functionalized magnetic nanoparticles shift cell behavior with on/off magnetic fields.

    Science.gov (United States)

    Jeon, Seongbeom; Subbiah, Ramesh; Bonaedy, Taufik; Van, Seyoung; Park, Kwideok; Yun, Kyusik

    2018-02-01

    Magnetic nanoparticles (MNPs) are used as contrast agents and targeted drug delivery systems (TDDS) due to their favorable size, surface charge, and magnetic properties. Unfortunately, the toxicity associated with MNPs limits their biological applications. Surface functionalization of MNPs with selective polymers alters the surface chemistry to impart better biocompatibility. We report the preparation of surface functionalized MNPs using iron oxide NPs (MNPs), poly (lactic-co-glycolic acid) (PLGA), and sodium alginate via co-precipitation, emulsification, and electro-spraying, respectively. The NPs are in the nanosize range and negatively charged. Morphological and structural analyses affirm the surface functionalized nanostructure of the NPs. The surface functionalized MNPs are biocompatible, and demonstrate enhanced intracellular delivery under an applied magnetic field (H), which evinces the targeting ability of MNPs. After NP treatment, the physico-mechanical properties of fibroblasts are decided by the selective MNP uptake under "on" or "off" magnetic field conditions. We envision potential use of biocompatible surface functionalized MNP for intracellular-, targeted-DDS, imaging, and for investigating cellular mechanics. © 2017 Wiley Periodicals, Inc.

  3. Surface modification influencing adsorption of red wine constituents: The role of functional groups

    Science.gov (United States)

    Mierczynska-Vasilev, Agnieszka; Smith, Paul A.

    2016-11-01

    The adsorption of wine constituents at solid surfaces is important in applications such as filtration and membrane fouling, binding to tanks and fittings and interactions with processing aids such as bentonite. The interaction of wine constituents with surfaces is mediated through adsorbed wine components, where the type of constituents, amount, orientation, and conformation are of consequence for the surface response. This study examines the effect of surface chemical functionalities on the adsorption of red wine constituents. Plasma-polymerized films rich in amine, carboxyl, hydroxyl, formyl and methyl functional groups were generated on solid substrates whereas, glycidyltrimethylammonium chloride was covalently attached to allylamine plasma-polymer modified surface and poly(sodium styrenesulfonate) was electrostatically adsorbed to an amine plasma-polymerized surface. The surface chemical functionalities were characterized by X-ray photoelectron spectroscopy. The ability of different substrates to adsorb red wine constituents was evaluated by quartz crystal microbalance and atomic force microscopy. The results showed that substrates modified with -SO3H and -COOH groups can adsorb more of the wine nitrogen-containing compounds whereas -NH2 and -NR3 groups encourage carbon-containing compounds adsorption. Red wine constituents after filtration were adsorbed in higher extend on -NR3 and -CHO surfaces. The -OH modified surfaces had the lowest ability to absorb wine components.

  4. Functionalization of CoCr surfaces with cell adhesive peptides to promote HUVECs adhesion and proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Castellanos, Maria Isabel, E-mail: maria.isabel.castellanos@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgical Engineering, Technical University of Catalonia (UPC), ETSEIB, 08028 Barcelona (Spain); Centre for Research in Nanoengineering (CRNE), UPC, 08028 Barcelona (Spain); Mas-Moruno, Carlos, E-mail: carles.mas.moruno@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgical Engineering, Technical University of Catalonia (UPC), ETSEIB, 08028 Barcelona (Spain); Centre for Research in Nanoengineering (CRNE), UPC, 08028 Barcelona (Spain); Grau, Anna, E-mail: agraugar@gmail.com [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgical Engineering, Technical University of Catalonia (UPC), ETSEIB, 08028 Barcelona (Spain); Centre for Research in Nanoengineering (CRNE), UPC, 08028 Barcelona (Spain); Serra-Picamal, Xavier, E-mail: xserrapicamal@gmail.com [Institute for Bioengineering of Catalonia (IBEC), 08028 Barcelona (Spain); University of Barcelona and CIBER-BBN, 08036 Barcelona (Spain); Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona (Spain); Trepat, Xavier, E-mail: xtrepat@ub.edu [Institute for Bioengineering of Catalonia (IBEC), 08028 Barcelona (Spain); University of Barcelona and CIBER-BBN, 08036 Barcelona (Spain); Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona (Spain); Albericio, Fernando, E-mail: fernando.albericio@irbbarcelona.org [Department of Chemistry, University of Barcelona, CIBER-BBN, 08028 Barcelona (Spain); Joner, Michael, E-mail: michaeljoner@me.com [Department of Cardiology, Deutsches Herzzentrum München, 80636 Munich (Germany); CVPath Institute, Gaithersburg, MD 20878 (United States); and others

    2017-01-30

    Highlights: • We immobilized peptides on CoCr alloy through physisorption and covalent bonding. • Surface activation is an essential step prior to silanization to enhance peptide attachment. • Biofunctionalized surface characteristics were discussed. • RGDS, YIGSR and combination peptides display an improved HUVECs adhesion and proliferation. - Abstract: Biomimetic surface modification with peptides that have specific cell-binding moieties is a promising approach to improve endothelialization of metal-based stents. In this study, we functionalized CoCr surfaces with RGDS, REDV, YIGSR peptides and their combinations to promote endothelial cells (ECs) adhesion and proliferation. An extensive characterization of the functionalized surfaces was performed by XPS analysis, surface charge and quartz crystal microbalance with dissipation monitoring (QCM-D), which demonstrated the successful immobilization of the peptides to the surface. Cell studies demonstrated that the covalent functionalization of CoCr surfaces with an equimolar combination of RGDS and YIGSR represents the most powerful strategy to enhance the early stages of ECs adhesion and proliferation, indicating a positive synergistic effect between the two peptide motifs. Although these peptide sequences slightly increased smooth muscle cells (SMCs) adhesion, these values were ten times lower than those observed for ECs. The combination of RGDS with the REDV sequence did not show synergistic effects in promoting the adhesion or proliferation of ECs. The strategy presented in this study holds great potential to overcome clinical limitations of current metal stents by enhancing their capacity to support surface endothelialization.

  5. Theoretical studies of the work functions of Pd-based bimetallic surfaces

    Science.gov (United States)

    Ding, Zhao-Bin; Wu, Feng; Wang, Yue-Chao; Jiang, Hong

    2015-06-01

    Work functions of Pd-based bimetallic surfaces, including mainly M/Pd(111), Pd/M, and Pd/M/Pd(111) (M = 4d transition metals, Cu, Au, and Pt), are studied using density functional theory. We find that the work function of these bimetallic surfaces is significantly different from that of parent metals. Careful analysis based on Bader charges and electron density difference indicates that the variation of the work function in bimetallic surfaces can be mainly attributed to two factors: (1) charge transfer between the two different metals as a result of their different intrinsic electronegativity, and (2) the charge redistribution induced by chemical bonding between the top two layers. The first factor can be related to the contact potential, i.e., the work function difference between two metals in direct contact, and the second factor can be well characterized by the change in the charge spilling out into vacuum. We also find that the variation in the work functions of Pd/M/Pd(111) surfaces correlates very well with the variation of the d-band center of the surface Pd atom. The findings in this work can be used to provide general guidelines to design new bimetallic surfaces with desired electronic properties.

  6. On-Surface Synthesis and Reactivity of Functional Organic and Metal-Organic Adsorbates at Metal Surfaces by Vibrational Spectroscopy

    Science.gov (United States)

    Williams, Christopher Glen

    Surface self-assembly is a promising way to introduce functionality to a surface through design at the molecular level. These self-assembled species allow for new on-surface type reactions to be observed and studied. The experiments described in this thesis demonstrate that the molecules used in self-assembly can potentially lead to interesting synthesis pathways and can be used to explore previously under-researched reaction pathways and surface molecular architecture activity or stability. Alkanes are an unreactive species typically used for driving molecular assembly in surface structures. However, with molecular design, alkanes are capable of reacting on surfaces not typically associated with alkane reactivity. Utilizing high-resolution electron energy loss spectroscopy (HREELS) and octaethylporphyrin, we could observe that dehydrogenation is possible on Cu(100) and Ag(111) surfaces at 500 and 610 K respectively. HREELS revealed that after the dehydrogenation, the molecule undergoes an intramolecular C-C bond formation leading to a tetrabenzo-porphyrin structure. Controls with deposited tetrabenzo-porphyrin were performed to verify the structure. This work provides the first example of dehydrocyclization on Cu(100) and Ag(111) to be analyzed by vibrational spectroscopy. Alkyl species in the 1,3,5-tris-(3,5-diethylphenyl)benzene molecule also undergo a dehydrogenation on Cu(100) and Au(111) at 450 and 500 K. The design of this molecule does not let the intramolecular dehydrocyclization reaction take place, but instead the dehydrogenation leads to intermolecular C-C bond formation between molecular species as noted by the formation of extended structure across the surface. Controls with triphenyl-benzene were done to help characterize the peaks in the spectra and observe varying reactivity when the ethyl groups are absent. The fabrication of uniform single-site metal centers at surfaces is important for higher selectivity in next-generation heterogeneous

  7. Microarray of neuroblastoma cells on the selectively functionalized nanocrystalline diamond thin film surface

    Energy Technology Data Exchange (ETDEWEB)

    Park, Young-Sang; Son, Hyeong-Guk; Kim, Dae-Hoon; Oh, Hong-Gi; Lee, Da-Som; Kim, Min-Hye; Lim, Ki-Moo; Song, Kwang-Soup, E-mail: kssong10@kumoh.ac.kr

    2016-01-15

    Graphical abstract: - Highlights: • The nanocrystalline diamond (NCD) surface is functionalized with F or O. • The cell adhesion and growth are evaluated on the functionalized NCD surface. • The cell adhesion and growth depend on the wettability of the surface. • Cell patterning was achieved by using of hydrophilic and hydrophobic surfaces. • Neuroblastoma cells were arrayed on the micro-patterned NCD surface. - Abstract: Nanocrystalline diamond (NCD) film surfaces were modified with fluorine or oxygen by plasma treatment in an O{sub 2} or C{sub 3}F{sub 8} gas environment in order to induce wettability. The oxygenated-NCD (O-NCD) film surface was hydrophilic and the fluorinated-NCD (F-NCD) surface was hydrophobic. The efficiency of early cell adhesion, which is dependent on the wettability of the cell culture plate and necessary for the growth and proliferation of cells, was 89.62 ± 3.92% on the O-NCD film and 7.78 ± 0.77% on the F-NCD film surface after 3 h of cell culture. The wettability of the NCD film surface was artificially modified using a metal mask and plasma treatment to fabricate a micro-pattern. Four types of micro-patterns were fabricated (line, circle, mesh, and word) on the NCD film surface. We precisely arrayed the neuroblastoma cells on the micro-patterned NCD film surfaces by controlling the surface wettability and cell seeding density. The neuroblastoma cells adhered and proliferated along the O-NCD film surface.

  8. Study of electron transport in the functionalized nanotubes and their impact on the electron transfer in the active site of horseradish peroxidase

    Science.gov (United States)

    Feizabadi, Mina; Ajloo, Davood; Soleymanpour, Ahmad; Faridnouri, Hassan

    2018-05-01

    Electrochemical characterization of functionalized carbon nanotubes (f-CNT) including carboxyl (CNT-COOH), amine (CNT-NH2) and hydroxyl (CNT-OH) functional groups were studied using differential pulse voltammetry (DPV). The current-voltage (I-V) curves were obtained from each system and the effect of f-CNT on redox interaction of horseradish peroxidase (HRP) immobilized on the electrode surface was investigated. The non-equilibrium Green's function (NEGF) combined with density functional theory (DFT) were used to study the transport properties of f-CNT. Additionally, the effect of the number of functional groups on transport properties of CNT, I-V characteristics, electronic transmission coefficients and spatial distribution of f-CNTs have been calculated and analyzed. The results showed that the carboxyl derivative has larger transmission coefficients and current value than other f-CNTs. Then, the effect of functional groups on the electron transport in heme group of HRP is discussed. Finally, the effect of a covalent bond between active site amino acids and amine functional group of CNT was investigated and discussed.

  9. Self-consistent Green’s-function technique for surfaces and interfaces

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt; Rosengaard, N. M.

    1991-01-01

    We have implemented an efficient self-consistent Green’s-function technique for calculating ground-state properties of surfaces and interfaces, based on the linear-muffin-tin-orbitals method within the tight-binding representation. In this approach the interlayer interaction is extremely short...... ranged, and only a few layers close to the interface need be treated self-consistently via a Dyson equation. For semi-infinite jellium, the technique gives work functions and surface energies that are in excellent agreement with earlier calculations. For the bcc(110) surface of the alkali metals, we find...

  10. Concatenation of electrochemical grafting with chemical or electrochemical modification for preparing electrodes with specific surface functionality

    International Nuclear Information System (INIS)

    Verma, Pallavi; Maire, Pascal; Novak, Petr

    2011-01-01

    Surface modified electrodes are used in electro-analysis, electro-catalysis, sensors, biomedical applications, etc. and could also be used in batteries. The properties of modified electrodes are determined by the surface functionality. Therefore, the steps involved in the surface modification of the electrodes to obtain specific functionality are of prime importance. We illustrate here bridging of two routes of surface modifications namely electrochemical grafting, and chemical or electrochemical reduction. First, by electrochemical grafting an organic moiety is covalently immobilized on the surface. Then, either by chemical or by electrochemical route the terminal functional group of the grafted moiety is transformed. Using the former route we prepared lithium alkyl carbonate (-O(CH 2 ) 3 OCO 2 Li) modified carbon with potential applications in batteries, and employing the latter we prepared phenyl hydroxyl amine (-C 6 H 4 NHOH) modified carbon which may find application in biosensors. Benzyl alcohol (-C 6 H 4 CH 2 OH) modified carbon was prepared by both chemical as well as electrochemical route. We report combinations of conjugating the two steps of surface modifications and show how the optimal route of terminal functional group modification depends on the chemical nature of the moiety attached to the surface in the electrochemical grafting step.

  11. Probability distribution for the Gaussian curvature of the zero level surface of a random function

    Science.gov (United States)

    Hannay, J. H.

    2018-04-01

    A rather natural construction for a smooth random surface in space is the level surface of value zero, or ‘nodal’ surface f(x,y,z)  =  0, of a (real) random function f; the interface between positive and negative regions of the function. A physically significant local attribute at a point of a curved surface is its Gaussian curvature (the product of its principal curvatures) because, when integrated over the surface it gives the Euler characteristic. Here the probability distribution for the Gaussian curvature at a random point on the nodal surface f  =  0 is calculated for a statistically homogeneous (‘stationary’) and isotropic zero mean Gaussian random function f. Capitalizing on the isotropy, a ‘fixer’ device for axes supplies the probability distribution directly as a multiple integral. Its evaluation yields an explicit algebraic function with a simple average. Indeed, this average Gaussian curvature has long been known. For a non-zero level surface instead of the nodal one, the probability distribution is not fully tractable, but is supplied as an integral expression.

  12. Continuous surface functionalization of flame-made TiO2 nanoparticles.

    Science.gov (United States)

    Teleki, Alexandra; Bjelobrk, Nada; Pratsinis, Sotiris E

    2010-04-20

    Hydrophilic TiO(2) particles made in a flame aerosol reactor were converted in situ to hydrophobic ones by silylation of their surface hydroxyl groups. So the freshly formed titania aerosol was mixed with a fine spray of octyltriethoxysilane (OTES) in water/ethanol solution and functionalized continuously at high temperature. The extent of functionalization and structure of that surface layer were assessed by thermogravimetric analysis (TGA) coupled to mass spectroscopy (MS), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), and Raman spectroscopy. Product particles were characterized also by transmission electron microscopy (TEM), X-ray diffraction, and nitrogen adsorption. The influence of titania specific surface area (SSA) and OTES solution concentration on the functional group surface density was investigated. The titanium dioxide surface was covered with functional groups (up to 2.9 wt %) that were thermally stable up to 300 degrees C in air at an average density of 2 OTES/nm(2). Such surface-functionalized particle suspensions in 2-ethylhexanoic acid and xylene were stable over several weeks. In contrast, as-prepared hydrophilic TiO(2) precipitated within days in these solvents.

  13. Template-controlled mineralization: Determining film granularity and structure by surface functionality patterns

    Directory of Open Access Journals (Sweden)

    Nina J. Blumenstein

    2015-08-01

    Full Text Available We present a promising first example towards controlling the properties of a self-assembling mineral film by means of the functionality and polarity of a substrate template. In the presented case, a zinc oxide film is deposited by chemical bath deposition on a nearly topography-free template structure composed of a pattern of two self-assembled monolayers with different chemical functionality. We demonstrate the template-modulated morphological properties of the growing film, as the surface functionality dictates the granularity of the growing film. This, in turn, is a key property influencing other film properties such as conductivity, piezoelectric activity and the mechanical properties. A very pronounced contrast is observed between areas with an underlying fluorinated, low energy template surface, showing a much more (almost two orders of magnitude coarse-grained film with a typical agglomerate size of around 75 nm. In contrast, amino-functionalized surface areas induce the growth of a very smooth, fine-grained surface with a roughness of around 1 nm. The observed influence of the template on the resulting clear contrast in morphology of the growing film could be explained by a contrast in surface adhesion energies and surface diffusion rates of the nanoparticles, which nucleate in solution and subsequently deposit on the functionalized substrate.

  14. Surface functionalization of graphite and carbon nanotubes by vacuum-ultraviolet photochemical reactions

    Energy Technology Data Exchange (ETDEWEB)

    Girard-Lauriault, Pierre-Luc, E-mail: pierre-luc.girard-lauriault@mcgill.ca [BAM Bundesanstalt fuer Materialforschung und - pruefung, D-12203 Berlin (Germany); Department of Chemical Engineering, McGill University, Montreal, H3A 2B2 (Canada); Illgen, Rene [BAM Bundesanstalt fuer Materialforschung und - pruefung, D-12203 Berlin (Germany); Ruiz, Juan-Carlos; Wertheimer, Michael R. [Groupe de Physique et Technologie des Couches Minces (GCM), Department of Engineering Physics, Ecole Polytechnique, Montreal, QC, H3C3A7 (Canada); Unger, Wolfgang E.S. [BAM Bundesanstalt fuer Materialforschung und - pruefung, D-12203 Berlin (Germany)

    2012-09-01

    Highlights: Black-Right-Pointing-Pointer Graphite and CNT surfaces were functionalized by VUV photochemistry in NH{sub 3} or O{sub 2}. Black-Right-Pointing-Pointer Significant amounts of N and O were incorporated at the materials surface. Black-Right-Pointing-Pointer Primary amine and hydroxyl groups were successfully incorporated at the surface. Black-Right-Pointing-Pointer NEXAFS permitted to assess the conservation of the aromatic structure. - Abstract: Graphite and multiwall carbon nanotube surfaces were functionalized by vacuum-ultraviolet induced photochemistry in NH{sub 3} or O{sub 2}, in order to introduce amino- (NH{sub 2}) or hydroxyl (OH) functionalities, respectively. Modified surfaces were characterized by X-ray photoelectron spectroscopy (XPS), which showed significant incorporation of nitrogen (N) and oxygen (O) at the materials' surface. While high-resolution XP spectra did not yield much specific information about the incorporated functional groups, chemical derivatization with 4-trifluoromethyl benzaldehyde and trifluoroacetic anhydride accompanied by XPS enabled quantification of NH{sub 2} and OH groups, respectively. Using near edge X-ray absorption fine structure spectroscopy, we assessed the conservation of the aromatic structure following functionalization treatments.

  15. Tribological investigations of the applicability of surface functionalization for dry extrusion processes

    Science.gov (United States)

    Teller, Marco; Prünte, Stephan; Ross, Ingo; Temmler, André; Schneider, Jochen M.; Hirt, Gerhard

    2017-10-01

    Cold extrusion processes are characterized by large relative contact stresses combined with a severe surface enlargement of the workpiece. Under these process conditions a high risk for galling of workpiece material to the tool steel occurs especially in processing of aluminum and aluminum alloys. In order to reduce adhesive wear lubricants for separation of workpiece and tool surfaces are used. As a consequence additional process steps (e.g. preparation and cleaning of workpieces) are necessary. Thus, the realization of a dry forming process is aspired from an environmental and economic perspective. In this paper a surface functionalization with self-assembled-monolayers (SAM) of the tool steels AISI D2 (DIN 1.2379) and AISI H11 (DIN 1.2343) is evaluated by a process-oriented tribological test. The tribological experiment is able to resemble and scale the process conditions of cold extrusion related to relative contact stress and surface enlargement for the forming of pure aluminum (Al99.5). The effect of reduced relative contact stress, surface enlargement and relative velocity on adhesive wear and tool lifetime is evaluated. Similar process conditions are achievable by different die designs with decreased extrusion ratios and adjusted die angles. The effect of surface functionalization critically depends on the substrate material. The different microstructure and the resulting differences in surface chemistry of the two tested tool steels appear to affect the performance of the tool surface functionalization with SAM.

  16. Work function anisotropy and surface stability of half-metallic CrO(2)

    NARCIS (Netherlands)

    Attema, J. J.; Uijttewaal, M. A.; de Wijs, G. A.; de Groot, R. A.

    Insight in the interplay between work function and stability is important for many areas of physics. In this paper, we calculate the anisotropy in the work function and the surface stability of CrO(2), a prototype half-metal, and find an anisotropy of 3.8 eV. An earlier model for the relation

  17. On-Site Surface Functionalization for Titanium Dental Implant with Nanotopography: Review and Outlook

    Directory of Open Access Journals (Sweden)

    Byung Gyu Kim

    2016-01-01

    Full Text Available Titanium (Ti has been the first choice of material for dental implant due to bonding ability to natural bone and great biocompatibility. Various types of surface roughness modification in nanoscale have been made as promising strategy for accelerating osseointegration of Ti dental implant. To have synergetic effect with nanotopography oriented favors in cell attachment, on-site surface functionalization with reproducibility of nanotopography is introduced as next strategy to further enhance cellular bioactivity. Extensive research has been conducted to investigate the potential of nanotopography preserved on-site surface functionalization for Ti dental implant. This review will discuss nonthermal atmospheric pressure plasma, ultraviolet, and low level of laser therapy on Ti dental implant with nanotopography as next generation of surface functionalization due to its abilities to induce superhydrophilicity or biofunctionality without change of nanotopography.

  18. Hand grip function assessed by the box and block test is affected by object surfaces.

    Science.gov (United States)

    Seo, Na Jin; Enders, Leah R

    2012-01-01

    N/A. One of the hand function assessment tools is the Box and Block Test (BBT). To examine if the BBT score is affected by grip surfaces. Thirteen adults performed the BBT with wooden, rubber-covered, and paper-covered blocks. The BBT scores and time for seven movements (finger closing, contact to lift-off, transport before barrier, transport after barrier, release, return, and reach) were compared across the three block types. The mean BBT score was 8% higher for the rubber blocks than the paper and wooden blocks (pblock until the block is lifted). Hand function assessments should be controlled for object surfaces. Therapists may vary grip difficulties by changing object surfaces. Redesigning daily objects with high-friction surfaces may increase grip function. N/A. Copyright © 2012 Hanley & Belfus. Published by Elsevier Inc. All rights reserved.

  19. Hot-electron-assisted femtochemistry at surfaces: A time-dependent density functional theory approach

    DEFF Research Database (Denmark)

    Gavnholt, Jeppe; Rubio, Angel; Olsen, Thomas

    2009-01-01

    Using time-evolution time-dependent density functional theory (TDDFT) within the adiabatic local-density approximation, we study the interactions between single electrons and molecular resonances at surfaces. Our system is a nitrogen molecule adsorbed on a ruthenium surface. The surface is modeled...... at two levels of approximation, first as a simple external potential and later as a 20-atom cluster. We perform a number of calculations on an electron hitting the adsorbed molecule from inside the surface and establish a picture, where the resonance is being probed by the hot electron. This enables us...

  20. Repellent materials. Robust self-cleaning surfaces that function when exposed to either air or oil.

    Science.gov (United States)

    Lu, Yao; Sathasivam, Sanjayan; Song, Jinlong; Crick, Colin R; Carmalt, Claire J; Parkin, Ivan P

    2015-03-06

    Superhydrophobic self-cleaning surfaces are based on the surface micro/nanomorphologies; however, such surfaces are mechanically weak and stop functioning when exposed to oil. We have created an ethanolic suspension of perfluorosilane-coated titanium dioxide nanoparticles that forms a paint that can be sprayed, dipped, or extruded onto both hard and soft materials to create a self-cleaning surface that functions even upon emersion in oil. Commercial adhesives were used to bond the paint to various substrates and promote robustness. These surfaces maintained their water repellency after finger-wipe, knife-scratch, and even 40 abrasion cycles with sandpaper. The formulations developed can be used on clothes, paper, glass, and steel for a myriad of self-cleaning applications. Copyright © 2015, American Association for the Advancement of Science.

  1. Robust self-cleaning surfaces that function when exposed to either air or oil

    Science.gov (United States)

    Lu, Yao; Sathasivam, Sanjayan; Song, Jinlong; Crick, Colin R.; Carmalt, Claire J.; Parkin, Ivan P.

    2015-03-01

    Superhydrophobic self-cleaning surfaces are based on the surface micro/nanomorphologies; however, such surfaces are mechanically weak and stop functioning when exposed to oil. We have created an ethanolic suspension of perfluorosilane-coated titanium dioxide nanoparticles that forms a paint that can be sprayed, dipped, or extruded onto both hard and soft materials to create a self-cleaning surface that functions even upon emersion in oil. Commercial adhesives were used to bond the paint to various substrates and promote robustness. These surfaces maintained their water repellency after finger-wipe, knife-scratch, and even 40 abrasion cycles with sandpaper. The formulations developed can be used on clothes, paper, glass, and steel for a myriad of self-cleaning applications.

  2. Photoresponsive switches at surfaces based on supramolecular functionalization with azobenzene-oligoglycerol conjugates.

    Science.gov (United States)

    Nachtigall, Olaf; Kördel, Christian; Urner, Leonhard H; Haag, Rainer

    2014-09-01

    The synthesis, supramolecular complexation, and switching of new bifunctional azobenzene-oligoglycerol conjugates in different environments is reported. Through the formation of host-guest complexes with surface immobilized β-cyclodextrin receptors, the bifunctional switches were coupled to gold surfaces. The isomerization of the amphiphilic azobenzene derivatives was examined in solution, on gold nanoparticles, and on planar gold surfaces. The wettability of functionalized gold surfaces can be reversibly switched under light-illumination with two different wavelengths. Besides the photoisomerization processes and concomitant effects on functionality, the thermal cis to trans isomerization of the conjugates and their complexes was monitored. Thermal half-lives of the cis isomers were calculated for different environments. Surprisingly, the half-lives on gold nanoparticles were significantly smaller compared to planar gold surfaces. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Surface functionalization of zirconium phosphate nanoplatelets for the design of polymer fillers.

    Science.gov (United States)

    Mosby, Brian M; Díaz, Agustín; Bakhmutov, Vladimir; Clearfield, Abraham

    2014-01-08

    Inorganic-organic hybrid materials were synthesized by covalent attachment of epoxides to the surface of zirconium phosphate (ZrP) nanoplatelets. X-ray powder diffraction, FTIR, and TGA were utilized to confirm the presence of the modifiers and exclusive functionalization of the ZrP surface. NMR experiments were conducted to confirm the formation of P-O-C bonds between surface phosphate groups and epoxide rings. The applicability of the organically modified products was demonstrated by their use as fillers in a polymer matrix. Subsequently, a two step intercalation and surface modification procedure was utilized to prepare polymer nanocomposites that were imparted with functionality through the encapsulation of molecules within the interlayer of surface modified ZrP.

  4. Molecular Characteristics and Biological Functions of Surface-Active and Surfactant Proteins.

    Science.gov (United States)

    Sunde, Margaret; Pham, Chi L L; Kwan, Ann H

    2017-06-20

    Many critical biological processes take place at hydrophobic:hydrophilic interfaces, and a wide range of organisms produce surface-active proteins and peptides that reduce surface and interfacial tension and mediate growth and development at these boundaries. Microorganisms produce both small lipid-associated peptides and amphipathic proteins that allow growth across water:air boundaries, attachment to surfaces, predation, and improved bioavailability of hydrophobic substrates. Higher-order organisms produce surface-active proteins with a wide variety of functions, including the provision of protective foam environments for vulnerable reproductive stages, evaporative cooling, and gas exchange across airway membranes. In general, the biological functions supported by these diverse polypeptides require them to have an amphipathic nature, and this is achieved by a diverse range of molecular structures, with some proteins undergoing significant conformational change or intermolecular association to generate the structures that are surface active.

  5. The impact of tool wear on the functionality of replicated polymer surface with micro structures

    DEFF Research Database (Denmark)

    Li, Dongya; Zhang, Yang; Regi, Francesco

    -axis micro milling ma-chine was employed to pattern the surface of a steel insert for subsequent polymer replication. In order to conduct the study, 1200 pixels (0.8 x 0.8 mm2) was machined on the surface of a steel insert using the same mill tool (Ф0.5 mm, ARNO®); each of the pixels contains16 ridges which...... is illustrated in figure 1 (a). The obtained surface structures were replicated using liquid silicon rubber (LSR). The mill tool was inspected by scanning electron microscope (SEM) before and after the machining. Noticeable wear was observed. The weight of the studied tool was measured before and after machining......Wear happened frequently in the tooling process of mold for polymer production. The scope of this paper is to understand how the wear of the milling tool affected the function of the replicated polymer surface. This study is part of the process chain of fabrication of optical functional surfaces...

  6. CO2 adsorption on the copper surfaces: van der Waals density functional and TPD studies

    Science.gov (United States)

    Muttaqien, Fahdzi; Hamamoto, Yuji; Hamada, Ikutaro; Inagaki, Kouji; Shiozawa, Yuichiro; Mukai, Kozo; Koitaya, Takanori; Yoshimoto, Shinya; Yoshinobu, Jun; Morikawa, Yoshitada

    2017-09-01

    We investigated the adsorption of CO2 on the flat, stepped, and kinked copper surfaces from density functional theory calculations as well as the temperature programmed desorption and X-ray photoelectron spectroscopy. Several exchange-correlation functionals have been considered to characterize CO2 adsorption on the copper surfaces. We used the van der Waals density functionals (vdW-DFs), i.e., the original vdW-DF (vdW-DF1), optB86b-vdW, and rev-vdW-DF2, as well as the Perdew-Burke-Ernzerhof (PBE) with dispersion correction (PBE-D2). We have found that vdW-DF1 and rev-vdW-DF2 functionals slightly underestimate the adsorption energy, while PBE-D2 and optB86b-vdW functionals give better agreement with the experimental estimation for CO2 on Cu(111). The calculated CO2 adsorption energies on the flat, stepped, and kinked Cu surfaces are 20-27 kJ/mol, which are compatible with the general notion of physisorbed species on solid surfaces. Our results provide a useful insight into appropriate vdW functionals for further investigation of related CO2 activation on Cu surfaces such as methanol synthesis and higher alcohol production.

  7. Neurodegenerative disease mutations in TREM2 reveal a functional surface and distinct loss-of-function mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Kober, Daniel L.; Alexander-Brett, Jennifer M.; Karch, Celeste M.; Cruchaga, Carlos; Colonna, Marco; Holtzman, Michael J.; Brett, Thomas J. (WU-MED)

    2016-12-20

    Genetic variations in the myeloid immune receptor TREM2 are linked to several neurodegenerative diseases. To determine how TREM2 variants contribute to these diseases, we performed structural and functional studies of wild-type and variant proteins. Our 3.1 Å TREM2 crystal structure revealed that mutations found in Nasu-Hakola disease are buried whereas Alzheimer’s disease risk variants are found on the surface, suggesting that these mutations have distinct effects on TREM2 function. Biophysical and cellular methods indicate that Nasu-Hakola mutations impact protein stability and decrease folded TREM2 surface expression, whereas Alzheimer’s risk variants impact binding to a TREM2 ligand. Additionally, the Alzheimer’s risk variants appear to epitope map a functional surface on TREM2 that is unique within the larger TREM family. These findings provide a guide to structural and functional differences among genetic variants of TREM2, indicating that therapies targeting the TREM2 pathway should be tailored to these genetic and functional differences with patient-specific medicine approaches for neurodegenerative disorders.

  8. Synthesis of nano-hydroxyapatite and its rapid mediated surface functionalization by silane coupling agent.

    Science.gov (United States)

    Rehman, Sarish; Khan, Kishwar; Mujahid, Mohammad; Nosheen, Shaneela

    2016-01-01

    In this work, hydroxyapatite (HA) nanorods were synthesized by simple one step wet precipitation method followed by their rapid surface functionalization via aminopropyltriethoxysilane (APTS) to give modified (HA-APTS) product. Functionalized hydroxyapatite (HA-APTS) holds amino groups on their surface that can be further functionalized with other bioactive molecules. The extent of functionalization of HA was studied under three different processing conditions; at room temperature, at 80 °C and under microwave condition (600 W). Three different temperatures have been use for the purpose of comparison between the functionalized products so that we can judge that whether there is any effect of temperature on the final products. In the last we conclude that temperature has no effect. So microwave condition is best to carried out the functionalization in just 5 min. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Control surfaces of aquatic vertebrates: active and passive design and function.

    Science.gov (United States)

    Fish, Frank E; Lauder, George V

    2017-12-01

    Aquatic vertebrates display a variety of control surfaces that are used for propulsion, stabilization, trim and maneuvering. Control surfaces include paired and median fins in fishes, and flippers and flukes in secondarily aquatic tetrapods. These structures initially evolved from embryonic fin folds in fishes and have been modified into complex control surfaces in derived aquatic tetrapods. Control surfaces function both actively and passively to produce torque about the center of mass by the generation of either lift or drag, or both, and thus produce vector forces to effect rectilinear locomotion, trim control and maneuvers. In addition to fins and flippers, there are other structures that act as control surfaces and enhance functionality. The entire body can act as a control surface and generate lift for stability in destabilizing flow regimes. Furthermore, control surfaces can undergo active shape change to enhance their performance, and a number of features act as secondary control structures: leading edge tubercles, wing-like canards, multiple fins in series, finlets, keels and trailing edge structures. These modifications to control surface design can alter flow to increase lift, reduce drag and enhance thrust in the case of propulsive fin-based systems in fishes and marine mammals, and are particularly interesting subjects for future research and application to engineered systems. Here, we review how modifications to control surfaces can alter flow and increase hydrodynamic performance. © 2017. Published by The Company of Biologists Ltd.

  10. Theoretical analysis of adsorption thermodynamics for hydrophobic peptide residues on SAM surfaces of varying functionality.

    Science.gov (United States)

    Latour, Robert A; Rini, Christopher J

    2002-06-15

    At a fundamental level, protein adsorption to a synthetic surface must be strongly influenced by the interaction between the peptide residues presented by the protein's surface (primary protein structure) and the functional groups presented by the synthetic surface. In this study, semi-empirical molecular modeling was used along with experimental wetting data to theoretically approach protein adsorption at this primary structural level. Changes in enthalpy, entropy, and Gibbs free energy were calculated as a function of residue-surface separation distance for the adsorption of individual hydrophobic peptide residues (valine, leucine, phenylalanine) on alkanethiol self-assembled monolayers on gold [Au-S(CH(2))(15)-X; X = CH(3), OH, NH(3)(+), COO(-)]. The results predict that the adsorption of each type of hydrophobic residue is energetically favorable and entropy dominated on a methyl-terminated hydrophobic surface, energetically unfavorable and enthalpy dominated on a hydroxyl-terminated neutral hydrophilic surface, and very slightly favorable to unfavorable and enthalpy dominated on charged surfaces. These theoretical results provide a basis for understanding some of the fundamental effects governing protein adsorption to synthetic surfaces. This level of understanding is needed for the proactive design of surfaces to control protein adsorption and subsequent cellular response for both implant and tissue engineering applications. Copyright 2002 Wiley Periodicals, Inc. J Biomed Mater Res 60: 564-577, 2002

  11. Surface analysis of gold nanoparticles functionalized with thiol-modified glucose SAMs for biosensor applications.

    Directory of Open Access Journals (Sweden)

    Valentina eSpampinato

    2016-02-01

    Full Text Available In this work, Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS, Principal Component Analysis (PCA and X-ray Photoelectron Spectroscopy (XPS have been used to characterize the surface chemistry of gold substrates before and after functionalization with thiol-modified glucose self-assembled monolayers and subsequent biochemical specific recognition of maltose binding protein (MBP.The results indicate that the surface functionalization is achieved both on flat and nanoparticles gold substrates thus showing the potential of the developed system as biodetection platform. Moreover, the method presented here has been found to be a sound and valid approach to characterize the surface chemistry of nanoparticles functionalized with large molecules.Both techniques were proved to be very useful tools for monitoring all the functionalization steps, including the investigation of the biological behaviour of the glucose-modified particles in presence of the maltose binding protein.

  12. Surface analysis of gold nanoparticles functionalized with thiol-modified glucose SAMs for biosensor applications.

    Science.gov (United States)

    Spampinato, Valentina; Parracino, Mariaantonietta; La Spina, Rita; Rossi, Francois; Ceccone, Giacomo

    2016-02-01

    In this work, Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS), Principal Component Analysis (PCA) and X-ray Photoelectron Spectroscopy (XPS) have been used to characterize the surface chemistry of gold substrates before and after functionalization with thiol-modified glucose self-assembled monolayers and subsequent biochemical specific recognition of maltose binding protein (MBP). The results indicate that the surface functionalization is achieved both on flat and nanoparticles gold substrates thus showing the potential of the developed system as biodetection platform. Moreover, the method presented here has been found to be a sound and valid approach to characterize the surface chemistry of nanoparticles functionalized with large molecules. Both techniques were proved to be very useful tools for monitoring all the functionalization steps, including the investigation of the biological behaviour of the glucose-modified particles in presence of the maltose binding protein.

  13. Adsorption of DNA binding proteins to functionalized carbon nanotube surfaces with and without DNA wrapping.

    Science.gov (United States)

    Ishibashi, Yu; Oura, Shusuke; Umemura, Kazuo

    2017-09-01

    We examined the adsorption of DNA binding proteins on functionalized, single-walled carbon nanotubes (SWNTs). When SWNTs were functionalized with polyethylene glycol (PEG-SWNT), moderate adsorption of protein molecules was observed. In contrast, nanotubes functionalized with CONH 2 groups (CONH 2 -SWNT) exhibited very strong interactions between the CONH 2 -SWNT and DNA binding proteins. Instead, when these SWNT surfaces were wrapped with DNA molecules (thymine 30-mers), protein binding was a little decreased. Our results revealed that DNA wrapped PEG-SWNT was one of the most promising candidates to realize DNA nanodevices involving protein reactions on DNA-SWNT surfaces. In addition, the DNA binding protein RecA was more adhesive than single-stranded DNA binding proteins to the functionalized SWNT surfaces.

  14. Enzyme-mimicking polymer brush-functionalized surface for combating biomaterial-associated infections

    Science.gov (United States)

    Jiang, Rujian; Xin, Zhirong; Xu, Shiai; Shi, Hengchong; Yang, Huawei; Song, Lingjie; Yan, Shunjie; Luan, Shifang; Yin, Jinghua; Khan, Ather Farooq; Li, Yonggang

    2017-11-01

    Biomaterial-associated infections critically compromise the functionality and performance of the medical devices, and pose a serious threat to human healthcare. Recently, natural DNase enzyme has been recognized as a potent material to prevent bacterial adhesion and biofilm formation. However, the vulnerability of DNase dramatically limits its long-term performance in antibacterial applications. In this work, DNase-mimicking polymer brushes were constructed to mimic the DNA-cleavage activity as well as the macromolecular scaffold of the natural DNase. The bacteria repellent efficacy of DNase-mimicking polymer brush-functionalized surface was comparable to that of the DNase-functionalized surface. More importantly, due to their inherent stability, DNase-mimicking polymer brushes presented the much better performance in inhibiting bacterial biofilm development for prolonged periods of time, as compared to the natural DNase. The as-developed DNase-mimicking polymer brush-functionalized surface presents a promising approach to combat biomaterial-associated infections.

  15. Surface modification influencing adsorption of red wine constituents: The role of functional groups

    Energy Technology Data Exchange (ETDEWEB)

    Mierczynska-Vasilev, Agnieszka, E-mail: agnieszka.mierczynska-vasilev@awri.com.au; Smith, Paul A., E-mail: paul.smith@awri.com.au

    2016-11-15

    Highlights: • Chemical surface composition affects behaviour of wine adsorption. • SO{sub 3}H and COOH groups adsorb more of the wine nitrogen-containing compounds. • NH{sub 2} and NR{sub 3} groups encourage carbon-containing compounds adsorption. • Red wine constituents after filtration adsorbed more on NR{sub 3} and CHO surfaces. - Abstract: The adsorption of wine constituents at solid surfaces is important in applications such as filtration and membrane fouling, binding to tanks and fittings and interactions with processing aids such as bentonite. The interaction of wine constituents with surfaces is mediated through adsorbed wine components, where the type of constituents, amount, orientation, and conformation are of consequence for the surface response. This study examines the effect of surface chemical functionalities on the adsorption of red wine constituents. Plasma-polymerized films rich in amine, carboxyl, hydroxyl, formyl and methyl functional groups were generated on solid substrates whereas, glycidyltrimethylammonium chloride was covalently attached to allylamine plasma-polymer modified surface and poly(sodium styrenesulfonate) was electrostatically adsorbed to an amine plasma-polymerized surface. The surface chemical functionalities were characterized by X-ray photoelectron spectroscopy. The ability of different substrates to adsorb red wine constituents was evaluated by quartz crystal microbalance and atomic force microscopy. The results showed that substrates modified with −SO{sub 3}H and –COOH groups can adsorb more of the wine nitrogen-containing compounds whereas −NH{sub 2} and −NR{sub 3} groups encourage carbon-containing compounds adsorption. Red wine constituents after filtration were adsorbed in higher extend on −NR{sub 3} and –CHO surfaces. The –OH modified surfaces had the lowest ability to absorb wine components.

  16. Surface modification influencing adsorption of red wine constituents: The role of functional groups

    International Nuclear Information System (INIS)

    Mierczynska-Vasilev, Agnieszka; Smith, Paul A.

    2016-01-01

    Highlights: • Chemical surface composition affects behaviour of wine adsorption. • SO 3 H and COOH groups adsorb more of the wine nitrogen-containing compounds. • NH 2 and NR 3 groups encourage carbon-containing compounds adsorption. • Red wine constituents after filtration adsorbed more on NR 3 and CHO surfaces. - Abstract: The adsorption of wine constituents at solid surfaces is important in applications such as filtration and membrane fouling, binding to tanks and fittings and interactions with processing aids such as bentonite. The interaction of wine constituents with surfaces is mediated through adsorbed wine components, where the type of constituents, amount, orientation, and conformation are of consequence for the surface response. This study examines the effect of surface chemical functionalities on the adsorption of red wine constituents. Plasma-polymerized films rich in amine, carboxyl, hydroxyl, formyl and methyl functional groups were generated on solid substrates whereas, glycidyltrimethylammonium chloride was covalently attached to allylamine plasma-polymer modified surface and poly(sodium styrenesulfonate) was electrostatically adsorbed to an amine plasma-polymerized surface. The surface chemical functionalities were characterized by X-ray photoelectron spectroscopy. The ability of different substrates to adsorb red wine constituents was evaluated by quartz crystal microbalance and atomic force microscopy. The results showed that substrates modified with −SO 3 H and –COOH groups can adsorb more of the wine nitrogen-containing compounds whereas −NH 2 and −NR 3 groups encourage carbon-containing compounds adsorption. Red wine constituents after filtration were adsorbed in higher extend on −NR 3 and –CHO surfaces. The –OH modified surfaces had the lowest ability to absorb wine components.

  17. Surface chemical functionalities affect the behavior of human adipose-derived stem cells in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xujie [State key laboratory of new ceramics and fine processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Feng, Qingling, E-mail: biomater@mail.tsinghua.edu.cn [State key laboratory of new ceramics and fine processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Bachhuka, Akash [Mawson Institute, University of South Australia, Mawson Lakes 5095 (Australia); Vasilev, Krasimir [Mawson Institute, University of South Australia, Mawson Lakes 5095 (Australia); School of Advanced Manufacturing, University of South Australia, Mawson Lakes 5095 (Australia)

    2013-04-01

    This study examines the effect of surface chemical functionalities on the behavior of human adipose-derived stem cells (hASCs) in vitro. Plasma polymerized films rich in amine (-NH{sub 2}), carboxyl (-COOH) and methyl (-CH{sub 3}), were generated on hydroxyapatite (HAp) substrates. The surface chemical functionalities were characterized by X-ray photoelectron spectroscopy (XPS). The ability of different substrates to absorb proteins was evaluated. The results showed that substrates modified with hydrophilic functional group (-COOH and -NH{sub 2}) can absorb more proteins than these modified with more hydrophobic functional group (-CH{sub 3}). The behavior of human adipose-derived stem cells (hASCs) cultured on different substrates was investigated in vitro: cell counting kit-8 (CCK-8) analysis was used to characterize cell proliferation, scanning electronic microscopy (SEM) analysis was used to characterize cell morphology and alkaline phosphatase (ALP) activity analysis was used to account for differentiation. The results of this study demonstrated that the -NH{sub 2} modified surfaces encourage osteogenic differentiation; the -COOH modified surfaces promote cell adhesion and spreading and the -CH{sub 3} modified surfaces have the lowest ability to induce osteogenic differentiation. These findings confirmed that the surface chemical states of biomaterials can affect the behavior of hASCs in vitro.

  18. Photo-induced functionalization of spherical and planar surfaces via caged thioaldehyde end-functional polymers

    Czech Academy of Sciences Publication Activity Database

    Kaupp, M.; Quick, A. S.; Rodriguez-Emmenegger, Cesar; Welle, A.; Trouillet, V.; Pop-Georgievski, Ognen; Wegener, M.; Barner-Kowollik, C.

    2014-01-01

    Roč. 24, č. 36 (2014), s. 5649-5661 ISSN 1616-301X R&D Projects: GA ČR GAP205/12/1702; GA ČR(CZ) GAP108/11/1857 Institutional support: RVO:61389013 Keywords : surface modification * porous materials * reversible addition fragmentation chain transfer polymerization Subject RIV: CD - Macromolecular Chemistry Impact factor: 11.805, year: 2014

  19. Improving the corrosion resistance of proton exchange membrane fuel cell carbon supports by pentafluorophenyl surface functionalization

    Science.gov (United States)

    Forouzandeh, Farisa; Li, Xiaoan; Banham, Dustin W.; Feng, Fangxia; Joseph Kakanat, Abraham; Ye, Siyu; Birss, Viola

    2018-02-01

    In this study, the effect of surface functionalization on the electrochemical corrosion resistance of a high surface area, mesoporous colloid imprinted carbon powder (CIC), as well as microporous Vulcan carbon (VC, serving as the benchmark), was demonstrated, primarily for PEM fuel cell applications. CIC-22, which is highly hydrophilic and was synthesized with 22 nm silica colloid templates, and as-received, mildly hydrophobic, VC powders, were functionalized with 2,3,4,5,6-pentafluorophenyl (-PhF5) surface groups using a straightforward diazonium reduction reaction. These carbons were then subjected to corrosion testing, involving a potential cycling-step sequence in room temperature 0.5 M H2SO4. Using cyclic voltammetry and charge/time analysis, the double layer and pseudo-capacitive gravimetric charges of the carbons, prior to and after the application of these potential steps, were tracked in order to obtain information about surface area changes and the extent of carbon oxidation, respectively. It is shown that the corrosion resistance was improved by ca. 50-80% by surface functionalization, likely due to a combination of surface passivation (loss of carbon active sites) and increased surface hydrophobicity.

  20. Correlation of H- production and the work function of a surface in a hydrogen plasma

    International Nuclear Information System (INIS)

    Wada, M.

    1983-01-01

    Surface-plasma negative hydrogen ion sources are being developed as possible parts for future netural beam systems. In these ion sources, negative hydrogen ions (H - ) are produced at low work function metal surfaces immersed in hydrogen plasmas. To investigate the correlation between the work function and the H-production at the surface with a condition similar to the one in the actual plasma ion source, these two parameters were simultaneously measured in the hydrogen plasma environment. The photoelectron emission currents from Mo and Cu surfaces in a cesiated hydrogen discharge were measured in the photon energy range from 1.45 to 4.14 eV, to determine the work function based on Fowler's theory. A small magnetic line cusp plasma container was specially designed to minimize the plasma noise and to realize the efficient collection of incident light onto the target. The photelectron current was detected phase sensitively and could be measured with reasonable accuracy up to about 5 x 10 11 cm -3 of the plasma electron density. As Cs density was increased in the hydrogen discharge, the work function decreased until it reached a minimum value. This value of the lowest work function was approximately 1.4 eV for both Mo and Cu surfaces, and the detected total H - current was a maximum at this condition

  1. Explaining electrostatic charging and flow of surface-modified acetaminophen powders as a function of relative humidity through surface energetics.

    Science.gov (United States)

    Jallo, Laila J; Dave, Rajesh N

    2015-07-01

    Powder flow involves particle-particle and particle-vessel contacts and separation resulting in electrostatic charging. This important phenomenon was studied for uncoated and dry-coated micronized acetaminophen (MAPAP) as a function of relative humidity. The main hypothesis is that by modifying powder surface energy via dry coating of MAPAP performed using magnetically assisted impaction coating, its charging tendency, flow can be controlled. The examination of the relationship between electrostatic charging, powder flow, and the surface energies of the powders revealed that an improvement in flow because of dry coating corresponded to a decrease in the charging of the particles. A general trend of reduction in both electrostatic charging and dispersive surface energy with dry coating and relative humidity were also observed, except that a divergent behavior was observed at higher relative humidities (≥55% RH). The uncoated powder was found to have strong electron acceptor characteristic as compared with the dry coated. The adhesion energy between the particles and the tubes used for the electrostatic charging qualitatively predicted the decreasing trend in electrostatic charging from plastic tubes to stainless steel. In summary, the surface energies of the powders and the vessel could explain the electrostatic charging behavior and charge reduction because of dry coating. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

  2. Function of Platelet-Induced Epithelial Attachment at Titanium Surfaces Inhibits Microbial Colonization.

    Science.gov (United States)

    Maeno, M; Lee, C; Kim, D M; Da Silva, J; Nagai, S; Sugawara, S; Nara, Y; Kihara, H; Nagai, M

    2017-06-01

    The aim of this study was to evaluate the barrier function of platelet-induced epithelial sheets on titanium surfaces. The lack of functional peri-implant epithelial sealing with basal lamina (BL) attachment at the interface of the implant and the adjacent epithelium allows for bacterial invasion, which may lead to peri-implantitis. Although various approaches have been reported to combat bacterial infection by surface modifications to titanium, none of these have been successful in a clinical application. In our previous study, surface modification with protease-activated receptor 4-activating peptide (PAR4-AP), which induced platelet activation and aggregation, was successful in demonstrating epithelial attachment via BL and epithelial sheet formation on the titanium surface. We hypothesized that the platelet-induced epithelial sheet on PAR4-AP-modified titanium surfaces would reduce bacterial attachment, penetration, and invasion. Titanium surface was modified with PAR4-AP and incubated with platelet-rich plasma (PRP). The aggregated platelets released collagen IV, a critical BL component, onto the PAR4-AP-modified titanium surface. Then, human gingival epithelial cells were seeded on the modified titanium surface and formed epithelial sheets. Green fluorescent protein (GFP)-expressing Escherichia coli was cultured onto PAR4-AP-modified titanium with and without epithelial sheet formation. While Escherichia coli accumulated densely onto the PAR4-AP titanium lacking epithelial sheet, few Escherichia coli were observed on the epithelial sheet on the PAR4-AP surface. No bacterial invasion into the interface of the epithelial sheet and the titanium surface was observed. These in vitro results indicate the efficacy of a platelet-induced epithelial barrier that functions to prevent bacterial attachment, penetration, and invasion on PAR4-AP-modified titanium.

  3. Accuracy of PfHRP2 versus Pf-pLDH antigen detection by malaria rapid diagnostic tests in hospitalized children in a seasonal hyperendemic malaria transmission area in Burkina Faso

    OpenAIRE

    Maltha, Jessica; Guiraud, Issa; Lompo, Palpouguini; Kaboré, Bérenger; Gillet, Philippe; Van Geet, Chris; Tinto, Halidou; Jacobs, Jan

    2014-01-01

    Background In most sub-Saharan African countries malaria rapid diagnostic tests (RDTs) are now used for the diagnosis of malaria. Most RDTs used detect Plasmodium falciparum histidine-rich protein-2 (PfHRP2), though P. falciparum-specific parasite lactate dehydrogenase (Pf-pLDH)-detecting RDTs may have advantages over PfHRP2-detecting RDTs. Only few data are available on the use of RDTs in severe illness and the present study compared Pf-pLDH to PfHRP2-detection. Methods Hospitalized children...

  4. Dithiocarbamate Self-Assembled Monolayers as Efficient Surface Modifiers for Low Work Function Noble Metals

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Dominik; Schäfer, Tobias; Schulz, Philip; Jung, Sebastian; Rittich, Julia; Mokros, Daniel; Segger, Ingolf; Maercks, Franziska; Effertz, Christian; Mazzarello, Riccardo; Wuttig, Matthias

    2016-09-06

    Tuning the work function of the electrode is one of the crucial steps to improve charge extraction in organic electronic devices. Here, we show that N,N-dialkyl dithiocarbamates (DTC) can be effectively employed to produce low work function noble metal electrodes. Work functions between 3.1 and 3.5 eV are observed for all metals investigated (Cu, Ag, and Au). Ultraviolet photoemission spectroscopy (UPS) reveals a maximum decrease in work function by 2.1 eV as compared to the bare metal surface. Electronic structure calculations elucidate how the complex interplay between intrinsic dipoles and dipoles induced by bond formation generates such large work function shifts. Subsequently, we quantify the improvement in contact resistance of organic thin film transistor devices with DTC coated source and drain electrodes. These findings demonstrate that DTC molecules can be employed as universal surface modifiers to produce stable electrodes for electron injection in high performance hybrid organic optoelectronics.

  5. Aminopropyltriethoxysilane-mediated surface functionalization of hydroxyapatite nanoparticles: synthesis, characterization, and in vitro toxicity assay.

    Science.gov (United States)

    Wang, Shige; Wen, Shihui; Shen, Mingwu; Guo, Rui; Cao, Xueyan; Wang, Jianhua; Shi, Xiangyang

    2011-01-01

    We report on aminopropyltriethoxysilane (APTS)-mediated surface modification of nanohydroxyapatite with different surface functional groups for potential biomedical applications. In this study, nanohydroxyapatite covalently linked with APTS (n-HA-APTS) was reacted with acetic anhydride or succinic anhydride to produce neutralized (n-HA-APTS. Ac) or negatively charged (n-HA-APTS.SAH) nanohydroxyapatite, respectively. Nanohydroxyapatite formed with amine, acetyl, and carboxyl groups was extensively characterized using Fourier transform infrared spectroscopy, transmission electron microscopy, (1)H nuclear magnetic resonance spectroscopy, X-ray diffraction, inductively coupled plasma-atomic emission spectroscopy, and zeta potential measurements. In vitro 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide colorimetric assay revealed that the slight toxicity of the amine-functionalized n-HA-APTS could be eliminated by post-functionalization of APTS amines to form acetyl and carboxyl groups. Blood compatibility assessment demonstrated that the negligible hemolytic activity of the pristine nanohydroxyapatite particles did not appreciably change after APTS-mediated surface functionalization. APTS-mediated functionalization of nanohydroxyapatite with different surface groups may be useful for further functionalization of nanohydroxyapatite with biologically active materials, thereby providing possibilities for a broad range of biomedical applications.

  6. Interaction of insulin with colloidal ZnS quantum dots functionalized by various surface capping agents.

    Science.gov (United States)

    Hosseinzadeh, Ghader; Maghari, Ali; Farniya, Seyed Morteza Famil; Keihan, Amir Homayoun; Moosavi-Movahedi, Ali A

    2017-08-01

    Interaction of quantum dots (QDs) and proteins strongly influenced by the surface characteristics of the QDs at the protein-QD interface. For a precise control of these surface-related interactions, it is necessary to improve our understanding in this field. In this regard, in the present work, the interaction between the insulin and differently functionalized ZnS quantum dots (QDs) were studied. The ZnS QDs were functionalized with various functional groups of hydroxyl (OH), carboxyl (COOH), amine (NH 2 ), and amino acid (COOH and NH 2 ). The effect of surface hydrophobicity was also studied by changing the alkyl-chain lengths of mercaptocarboxylic acid capping agents. The interaction between insulin and the ZnS QDs were investigated by fluorescence quenching, synchronous fluorescence, circular dichroism (CD), and thermal aggregation techniques. The results reveal that among the studied QDs, mercaptosuccinic acid functionalized QDs has the strongest interaction (∆G ° =-51.50kJ/mol at 310K) with insulin, mercaptoethanol functionalized QDs destabilize insulin by increasing the beta-sheet contents, and only cysteine functionalized QDs improves the insulin stability by increasing the alpha-helix contents of the protein, and. Our results also indicate that by increasing the alkyl-chain length of capping agents, due to an increase in hydrophobicity of the QDs surface, the beta-sheet contents of insulin increase which results in the enhancement of insulin instability. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Effects of chemical functional groups on elemental mercury adsorption on carbonaceous surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Liu Jing, E-mail: liujing27@mail.hust.edu.cn [State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074 (China); Cheney, Marcos A. [Department of Natural Sciences, University of Maryland Eastern Shore, Princess Anne, MD 21853 (United States); Wu Fan; Li Meng [State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2011-02-15

    A systematic theoretical study using density functional theory is performed to provide molecular-level understanding of the effects of chemical functional groups on mercury adsorption on carbonaceous surfaces. The zigzag and armchair edges were used in modeling the carbonaceous surfaces to simulate different adsorption sites. The edge atoms on the upper side of the models are unsaturated to simulate active sites. All calculations (optimizations, energies, and frequencies) were made at B3PW91 density functional theory level, using RCEP60VDZ basis set for mercury and 6-31G(d) pople basis set for other atoms. The results indicate that the embedding of halogen atom can increase the activity of its neighboring site which in turn increases the adsorption capacity of the carbonaceous surface for Hg{sup 0}. The adsorption belongs to chemisorptions, which is in good agreement with the experimental results. For the effects of oxygen functional groups, lactone, carbonyl and semiquinone favor Hg{sup 0} adsorption because they increase the neighboring site's activity for mercury adsorption. On the contrary, phenol and carboxyl functional groups show a physisorption of Hg{sup 0}, and reduce Hg capture. This result can explain the seemingly conflicting experimental results reported in the literature concerning the influence of oxygen functional groups on mercury adsorption on carbonaceous surface.

  8. Adhesion, invasion and evasion: the many functions of the surface proteins of Staphylococcus aureus

    Science.gov (United States)

    Foster, Timothy J.; Geoghegan, Joan A.; Ganesh, Vannakambadi K.; Höök, Magnus

    2014-01-01

    Staphylococcus aureus is an important opportunistic pathogen and persistently colonizes about 20% of the human population. Its surface is ‘decorated’ with proteins that are covalently anchored to the cell wall peptidoglycan. Structural and functional analysis has identified four distinct classes of surface proteins, of which microbial surface component recognizing adhesive matrix molecules (MSCRAMMs) are the largest class. These surface proteins have numerous functions, including adhesion to and invasion of host cells and tissues, evasion of immune responses and biofilm formation. Thus, cell wall-anchored proteins are essential virulence factors for the survival of S. aureus in the commensal state and during invasive infections, and targeting them with vaccines could combat S. aureus infections. PMID:24336184

  9. Functionalization of SU-8 Photoresist Surfaces with IgG Proteins

    DEFF Research Database (Denmark)

    Blagoi, Gabriela; Keller, Stephan Urs; Johansson, Alicia

    2008-01-01

    The negative epoxy-based photoresist SU-8 has a variety of applications within microelectromechanical systems (MEMS) and lab-on-a-chip systems. Here, several methods to functionalize SU-8 surfaces with IgG proteins were investigated. Fluorescent labeled proteins and fluorescent sandwich...... immunoassays were employed to characterize the binding efficiency of model proteins to bare SU-8 surface, SU-8 treated with cerium ammonium nitrate (CAN) etchant and CAN treated surfaces modified by aminosilanization. The highest binding capacity of antibodies was observed on bare SU-8. This explains why bare...... SU-8 in a functional fluorescent sandwich immunoassay detecting C-reactive protein (CRP) gave twice as high signal as compared with the other two surfaces. Immunoassays performed on bare SU-8 and CAN treated SU-8 resulted in detection limits of CRP of 30 and 80 ng/ml respectively which is sufficient...

  10. Coverage-driven dissociation of azobenzene on Cu(111): a route towards defined surface functionalization.

    Science.gov (United States)

    Willenbockel, Martin; Maurer, Reinhard J; Bronner, Christopher; Schulze, Michael; Stadtmüller, Benjamin; Soubatch, Serguei; Tegeder, Petra; Reuter, Karsten; Stefan Tautz, F

    2015-10-25

    We investigate the surface-catalyzed dissociation of the archetypal molecular switch azobenzene on the Cu(111) surface. Based on X-ray photoelectron spectroscopy, normal incidence X-ray standing waves and density functional theory calculations a detailed picture of the coverage-induced formation of phenyl nitrene from azobenzene is presented. Furthermore, a comparison to the azobenzene/Ag(111) interface provides insight into the driving force behind the dissociation on Cu(111). The quantitative decay of azobenzene paves the way for the creation of a defect free, covalently bonded monolayer. Our work suggests a route of surface functionalization via suitable azobenzene derivatives and the on surface synthesis concept, allowing for the creation of complex immobilized molecular systems.

  11. Development of measurement standards for verifying functional performance of surface texture measuring instruments

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, A [Life and Industrial Product Development Department Olympus Corporation, 2951 Ishikawa-machi, Hachiouji-shi, Tokyo (Japan); Suzuki, H [Industrial Marketing and Planning Department Olympus Corporation, Shinjyuku Monolith, 3-1 Nishi-Shinjyuku 2-chome, Tokyo (Japan); Yanagi, K, E-mail: a_fujii@ot.olympus.co.jp [Department of Mechanical Engineering, Nagaoka University of Technology, 1603-1 Kamitomioka-machi, Nagaoka-shi, Niigata (Japan)

    2011-08-19

    A new measurement standard is proposed for verifying overall functional performance of surface texture measuring instruments. Its surface is composed of sinusoidal surface waveforms of chirp signals along horizontal cross sections of the material measure. One of the notable features is that the amplitude of each cycle in the chirp signal form is geometrically modulated so that the maximum slope is kept constant. The maximum slope of the chirp-like signal is gradually decreased according to movement in the lateral direction. We fabricated the measurement standard by FIB processing, and it was calibrated by AFM. We tried to evaluate the functional performance of Laser Scanning Microscope by this standard in terms of amplitude response with varying slope angles. As a result, it was concluded that the proposed standard can easily evaluate the performance of surface texture measuring instruments.

  12. Self-consistent density functional calculation of the image potential at a metal surface

    Energy Technology Data Exchange (ETDEWEB)

    Jung, J [Departamento de Fisica Fundamental, Universidad Nacional de Educacion a Distancia, Apartado 60141, 28080 Madrid (Spain); Alvarellos, J E [Departamento de Fisica Fundamental, Universidad Nacional de Educacion a Distancia, Apartado 60141, 28080 Madrid (Spain); Chacon, E [Instituto de Ciencias de Materiales de Madrid, Consejo Superior de Investigaciones CientIficas, E-28049 Madrid (Spain); GarcIa-Gonzalez, P [Departamento de Fisica Fundamental, Universidad Nacional de Educacion a Distancia, Apartado 60141, 28080 Madrid (Spain)

    2007-07-04

    It is well known that the exchange-correlation (XC) potential at a metal surface has an image-like asymptotic behaviour given by -1/4(z-z{sub 0}), where z is the coordinate perpendicular to the surface. Using a suitable fully non-local functional prescription, we evaluate self-consistently the XC potential with the correct image behaviour for simple jellium surfaces in the range of metallic densities. This allows a proper comparison between the corresponding image-plane position, z{sub 0}, and other related quantities such as the centroid of an induced charge by an external perturbation. As a by-product, we assess the routinely used local density approximation when evaluating electron density profiles, work functions, and surface energies by focusing on the XC effects included in the fully non-local description.

  13. Self-consistent density functional calculation of the image potential at a metal surface

    International Nuclear Information System (INIS)

    Jung, J; Alvarellos, J E; Chacon, E; GarcIa-Gonzalez, P

    2007-01-01

    It is well known that the exchange-correlation (XC) potential at a metal surface has an image-like asymptotic behaviour given by -1/4(z-z 0 ), where z is the coordinate perpendicular to the surface. Using a suitable fully non-local functional prescription, we evaluate self-consistently the XC potential with the correct image behaviour for simple jellium surfaces in the range of metallic densities. This allows a proper comparison between the corresponding image-plane position, z 0 , and other related quantities such as the centroid of an induced charge by an external perturbation. As a by-product, we assess the routinely used local density approximation when evaluating electron density profiles, work functions, and surface energies by focusing on the XC effects included in the fully non-local description

  14. Enhancing the efficiency of lithium intercalation in carbon nanotube bundles using surface functional groups.

    Science.gov (United States)

    Xiao, Shiyan; Zhu, Hong; Wang, Lei; Chen, Liping; Liang, Haojun

    2014-08-14

    The effect of surface functionalization on the ability and kinetics of lithium intercalation in carbon nanotube (CNT) bundles has been studied by comparing the dynamical behaviors of lithium (Li) ions in pristine and -NH2 functionalized CNTs via ab initio molecular dynamics simulations. It was observed that lithium intercalation has been achieved quickly for both the pristine and surface functionalized CNT bundle. Our calculations demonstrated for the first time that CNT functionalization improved the efficiency of lithium intercalation significantly at both low and high Li ion density. Moreover, we found that keeping the nanotubes apart with an appropriate distance and charging the battery at a rational rate were beneficial to achieve a high rate of lithium intercalation. Besides, the calculated adsorption energy curves indicated that the potential wells in the system of -NH2 functionalized CNT were deeper than that of the pristine CNT bundle by 0.74 eV, and a third energy minimum with a value of 2.64 eV existed at the midpoint of the central axis of the nanotube. Thus, it would be more difficult to remove Li ions from the nanotube interior after surface functionalization. The barrier for lithium diffusion in the interior of the nanotube is greatly decreased because of the surface functional groups. Based on these results, we would suggest to "damage" the nanotube by introducing defects at its sidewall in order to improve not only the capacity of surface functionalized CNTs but also the efficiency of lithium intercalation and deintercalation processes. Our results presented here are helpful in understanding the mechanism of lithium intercalation into nanotube bundles, which may potentially be applied in the development of CNT based electrodes.

  15. Enhanced surface functionality via plasma modification and plasma deposition techniques to create more biologically relevant materials

    Science.gov (United States)

    Shearer, Jeffrey C.

    Functionalizing nanoparticles and other unusually shaped substrates to create more biologically relevant materials has become central to a wide range of research programs. One of the primary challenges in this field is creating highly functionalized surfaces without modifying the underlying bulk material. Traditional wet chemistry techniques utilize thin film depositions to functionalize nanomaterials with oxygen and nitrogen containing functional groups, such as --OH and --NHx. These functional groups can serve to create surfaces that are amenable to cell adhesion or can act as reactive groups for further attachment of larger structures, such as macromolecules or antiviral agents. Additional layers, such as SiO2, are often added between the nanomaterial and the functionalized coating to act as a barrier films, adhesion layers, and to increase overall hydrophilicity. However, some wet chemistry techniques can damage the bulk material during processing. This dissertation examines the use of plasma processing as an alternative method for producing these highly functionalized surfaces on nanoparticles and polymeric scaffolds through the use of plasma modification and plasma enhanced chemical vapor deposition techniques. Specifically, this dissertation will focus on (1) plasma deposition of SiO2 barrier films on nanoparticle substrates; (2) surface functionalization of amine and alcohol groups through (a) plasma co-polymerization and (b) plasma modification; and (3) the design and construction of plasma hardware to facilitate plasma processing of nanoparticles and polymeric scaffolds. The body of work presented herein first examines the fabrication of composite nanoparticles by plasma processing. SiOxC y and hexylamine films were coated onto TiO2 nanoparticles to demonstrate enhanced water dispersion properties. Continuous wave and pulsed allyl alcohol plasmas were used to produce highly functionalized Fe2 O3 supported nanoparticles. Specifically, film composition was

  16. Straightforward and robust synthesis of monodisperse surface-functionalized gold nanoclusters

    Directory of Open Access Journals (Sweden)

    Silvia Varela-Aramburu

    2016-09-01

    Full Text Available Gold nanoclusters are small (1–3 nm nanoparticles with a high surface area that are useful for biomedical studies and drug delivery. The synthesis of small, surface-functionalized gold nanoclusters is greatly dependent on the reaction conditions. Here, we describe a straightforward, efficient and robust room temperature one-pot synthesis of 2 nm gold nanoclusters using thioglucose as a reducing and stabilizing agent, which was discovered by serendipity. The resultant monodisperse gold nanoclusters are more stable than those generated using some other common methods. The carboxylic acid contained in the stabilizing agent on the cluster surface serves as anchor for nanocluster functionalization. Alternatively, the addition of thiols serves to functionalize the nanoclusters. The resulting non-cytotoxic nanoclusters are taken up by cells and constitute a tuneable platform for biomedical applications including drug delivery.

  17. Azetidinium Functionalized Polytetrahydrofurans: Antimicrobial Properties in Solution and Application to Prepare Non Leaching Antimicrobial Surfaces

    Directory of Open Access Journals (Sweden)

    Subrata Chattopadhyay

    2014-05-01

    Full Text Available In this work, we report the antimicrobial efficacy of azetidinium functionalized polytetrahydrofurans in solution and their application in the preparation of non leaching, antimicrobial surfaces. The excellent antimicrobial efficacy of these water soluble polymers both in solution and on surfaces (>99.99%–100% bacterial growth inhibition makes them excellent candidates for solving the hygiene related problems in the medical and hospital environment.

  18. Drug delivery to the bone-implant interface: Functional hydroxyapatite surfaces and particles

    OpenAIRE

    Schüssele, Andrea

    2007-01-01

    With the goal of controlling the events at the bone-implant interface, it was the main objective of this thesis to provide a basis for the conjugation of cell stimulating molecules or targeting motifs to the surface of hydroxyapatite ceramic discs and particles. To this end, methods for surface functionalization have been investigated for the attachment of biomolecules. The approach focused on combining three approved and effective principles for enhanced osseointegration of implants: hydroxy...

  19. Relationship between specific surface area and spatial correlation functions for anisotropic porous media

    Energy Technology Data Exchange (ETDEWEB)

    Berryman, J.G.

    1987-01-01

    A result of Debye, Anderson, and Brumberger (P. Debye, H. R. Anderson, Jr., and H. Brumberger, J. Appl. Phys. 28, 679 (1957)) for isotropic porous media states that the derivative of the two-point spatial correlation at the origin is equal to minus one-quarter of the specific surface area. This result is generalized for nonisotropic media by noting that the angular average of the anisotropic two-point spatial correlation function has the same relationship to the specific surface area.

  20. Covalent Functionalization of NiTi Surfaces with Bioactive Peptide Amphiphile Nanofibers

    Science.gov (United States)

    Sargeant, Timothy D.; Rao, Mukti S.; Koh, Chung-Yan

    2009-01-01

    Surface modification enables the creation of bioactive implants using traditional material substrates without altering the mechanical properties of the bulk material. For applications such as bone plates and stents, it is desirable to modify the surface of metal alloy substrates to facilitate cellular attachment, proliferation, and possibly differentiation. In this work we present a general strategy for altering the surface chemistry of nickel-titanium shape memory alloy (NiTi) in order to covalently attach self-assembled peptide amphiphile (PA) nanofibers with bioactive functions. Bioactivity in the systems studied here includes biological adhesion and proliferation of osteoblast and endothelial cell types. The optimized surface treatment creates a uniform TiO2 layer with low levels of Ni on the NiTi surface, which is subsequently covered with an aminopropylsilane coating using a novel, lower temperature vapor deposition method. This method produces an aminated surface suitable for covalent attachment of PA molecules containing terminal carboxylic acid groups. The functionalized NiTi surfaces have been characterized by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectroscopy (ToF-SIMS), and atomic force microscopy (AFM). These techniques offer evidence that the treated metal surfaces consist primarily of TiO2 with very little Ni, and also confirm the presence of the aminopropylsilane overlayer. Self-assembled PA nanofibers presenting the biological peptide adhesion sequence Arg-Gly-Asp-Ser are capable of covalently anchoring to the treated substrate, as demonstrated by spectrofluorimetry and AFM. Cell culture and scanning electron microscopy (SEM) demonstrate cellular adhesion, spreading, and proliferation on these functionalized metal surfaces. Furthermore, these experiments demonstrate that covalent attachment is crucial for creating robust PA nanofiber coatings, leading to confluent cell monolayers. PMID:18083225

  1. Simultaneous measurements of work function and H‒ density including caesiation of a converter surface

    Science.gov (United States)

    Cristofaro, S.; Friedl, R.; Fantz, U.

    2017-08-01

    Negative hydrogen ion sources rely on the surface conversion of neutral atomic hydrogen and positive hydrogen ions to H-. The efficiency of this process depends on the actual work function of the converter surface. By introducing caesium into the source the work function decreases, enhancing the negative ion yield. In order to study the impact of the work function on the H- surface production at similar conditions to the ones in ion sources for fusion devices like ITER and DEMO, fundamental investigations are performed in a flexible laboratory experiment. The work function of the converter surface can be absolutely measured by photoelectric effect, while a newly installed cavity ring-down spectroscopy system (CRDS) measures the H- density. The CRDS is firstly tested and characterized by investigations on H- volume production. Caesiation of a stainless steel sample is then performed in vacuum and the plasma effect on the Cs layer is investigated also for long plasma-on times. A minimum work function of (1.9±0.1) eV is reached after some minutes of plasma treatment, resulting in a reduction by a value of 0.8 eV compared to vacuum measurements. The H- density above the surface is (2.1±0.5)×1015 m-3. With further plasma exposure of the caesiated surface, the work function increases up to 3.75 eV, due to the impinging plasma particles which gradually remove the Cs layer. As a result, the H- density decreases by a factor of at least 2.

  2. FUNCTIONAL SURFACE MICROGEOMETRY PROVIDING THE DESIRED PERFORMANCE OF AN AIRCRAFT VIBRATION SENSOR

    Directory of Open Access Journals (Sweden)

    Yuriy S. Andreev

    2016-11-01

    Full Text Available Subject of Research. The paper deals with the methods of efficiency improving for piezoelectric vibration sensors used in aircraft industry to control the level of vibration of gas turbine engines. The study looks into the matter of surface microgeometry effect of the vibro sensor part on its transverse sensitivity ratio. Measures are proposed to improve the sensor performance without cost supplement by optimization of the functional surface microgeometry. Method. A method for determination of the best possible surface microgeometry within the specific production conditions is shown. Also, a method for microgeometry estimation of the functional surfaces using graphical criteria is used. Taguchi method is used for design of experiment for functional surfaces machining. The use of this method reduces significantly the number of experiments without validity loss. Main Results. The relationship between technological factors of manufacturing the vibration sensor parts and its sensitivity has been found out. The optimal surface machining methods and process conditions for parts ensuring the best possible sensitivity have been determined. Practical Relevance. Research results can be used by instrument-making companies to improve the process of piezoelectric vibration sensor design and manufacturing.

  3. Folic acid functionalized surface highlights 5-methylcytosine-genomic content within circulating tumor cells

    KAUST Repository

    Malara, Natalia

    2014-07-01

    Although the detection of methylated cell free DNA represents one of the most promising approaches for relapse risk assessment in cancer patients, the low concentration of cell-free circulating DNA constitutes the biggest obstacle in the development of DNA methylation-based biomarkers from blood. This paper describes a method for the measurement of genomic methylation content directly on circulating tumor cells (CTC), which could be used to deceive the aforementioned problem. Since CTC are disease related blood-based biomarkers, they result essential to monitor tumor\\'s stadiation, therapy, and early relapsing lesions. Within surface\\'s bio-functionalization and cell\\'s isolation procedure standardization, the presented approach reveals a singular ability to detect high 5-methylcytosine CTC-subset content in the whole CTC compound, by choosing folic acid (FA) as transducer molecule. Sensitivity and specificity, calculated for FA functionalized surface (FA-surface), result respectively on about 83% and 60%. FA-surface, allowing the detection and characterization of early metastatic dissemination, provides a unique advance in the comprehension of tumors progression and dissemination confirming the presence of CTC and its association with high risk of relapse. This functionalized surface identifying and quantifying high 5-methylcytosine CTC-subset content into the patient\\'s blood lead significant progress in cancer risk assessment, also providing a novel therapeutic strategy.© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Surface-functionalized cockle shell–based calcium carbonate aragonite polymorph as a drug nanocarrier

    Science.gov (United States)

    Mohd Abd Ghafar, Syairah Liyana; Hussein, Mohd Zobir; Rukayadi, Yaya; Abu Bakar Zakaria, Md Zuki

    2017-01-01

    Calcium carbonate aragonite polymorph nanoparticles derived from cockle shells were prepared using surface functionalization method followed by purification steps. Size, morphology, and surface properties of the nanoparticles were characterized using transmission electron microscopy, field emission scanning electron microscopy, dynamic light scattering, zetasizer, X-ray powder diffraction, and Fourier transform infrared spectrometry techniques. The potential of surface-functionalized calcium carbonate aragonite polymorph nanoparticle as a drug-delivery agent were assessed through in vitro drug-loading test and drug-release test. Transmission electron microscopy, field emission scanning electron microscopy, and particle size distribution analyses revealed that size, morphology, and surface characterization had been improved after surface functionalization process. Zeta potential of the nanoparticles was found to be increased, thereby demonstrating better dispersion among the nanoparticles. Purification techniques showed a further improvement in the overall distribution of nanoparticles toward more refined size ranges nanoparticles derived from cockle shells, a natural biomaterial, with modified surface characteristics are promising and can be applied as efficient carriers for drug delivery. PMID:28572724

  5. Cavitand-functionalized porous silicon as an active surface for organophosphorus vapor detection.

    Science.gov (United States)

    Tudisco, Cristina; Betti, Paolo; Motta, Alessandro; Pinalli, Roberta; Bombaci, Luigi; Dalcanale, Enrico; Condorelli, Guglielmo G

    2012-01-24

    This paper reports on the preparation of a porous silicon-based material covalently functionalized with cavitand receptors suited for the detection of organophosphorus vapors. Two different isomeric cavitands, both containing one acid group at the upper rim, specifically designed for covalent anchoring on silicon, were grafted on H-terminated porous silicon (PSi) by thermal hydrosilylation. The covalently functionalized surfaces and their complexation properties were characterized by combining different analytical techniques, namely X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and mass spectroscopy analysis coupled with thermal desorption experiments. Complexation experiments were performed by exposing both active surfaces and a control surface consisting of PSi functionalized with a structurally similar but inactive methylene-bridged cavitand (MeCav) to dimethyl methylphosphonate (DMMP) vapors. Comparison between active and inactive surfaces demonstrated the recognition properties of the new surfaces. Finally, the nature of the involved interactions, the energetic differences between active and inactive surfaces toward DMMP complexation, and the comparison with a true nerve gas agent (sarin) were studied by DFT modeling. The results revealed the successful grafting reaction, the specific host-guest interactions of the PSi-bonded receptors, and the reversibility of the guest complexation.

  6. Influence of neutral surface position on the nonlinear stability behavior of functionally graded plates

    Science.gov (United States)

    Prakash, T.; Singha, M. K.; Ganapathi, M.

    2009-02-01

    Nonlinear behavior of functionally graded material (FGM) skew plates under in-plane load is investigated here using a shear deformable finite element method. The material is graded in the thickness direction and a simple power law based on the rule of mixture is used to estimate the effective material properties. The neutral surface position for such FGM plates is determined and the first order shear deformation theory based on exact neutral surface position is employed here. The present model is compared with the conventional mid-surface based formulation, which uses extension-bending coupling matrix to include the noncoincidence of neutral surface with the geometric mid-surface for unsymmetric plates. The nonlinear governing equations are solved through Newton Raphson technique. The nonlinear behavior of FGM skew plates under compressive and tensile in-plane load are examined considering different system parameters such as constituent gradient index, boundary condition, thickness-to-span ratio and skew angle.

  7. Integrated Mecical Model (IMM) 4.0 Verification and Validation (VV) Testing (HRP IWS 2016)

    Science.gov (United States)

    Walton, M; Kerstman, E.; Arellano, J.; Boley, L.; Reyes, D.; Young, M.; Garcia, Y.; Saile, L.; Myers, J.

    2016-01-01

    Timeline, partial treatment, and alternate medications were added to the IMM to improve the fidelity of this model to enhance decision support capabilities. Using standard design reference missions, IMM VV testing compared outputs from the current operational IMM (v3) with those from the model with added functionalities (v4). These new capabilities were examined in a comparative, stepwise approach as follows: a) comparison of the current operational IMM v3 with the enhanced functionality of timeline alone (IMM 4.T), b) comparison of IMM 4.T with the timeline and partial treatment (IMM 4.TPT), and c) comparison of IMM 4.TPT with timeline, partial treatment and alternative medication (IMM 4.0).

  8. Hydrophobic surface functionalization of Philippine natural zeolite for a targeted oil remediation application

    Science.gov (United States)

    Osonio, Airah P.; Olegario-Sanchez, Eleanor M.

    2017-12-01

    The objective of this study is to modify and compare the oil sorption capacity on the surface of natural zeolite (NZ) and functionalized natural zeolite (FNZ) and to compare with activated charcoal samples. The NZ samples were surface modified via esterification process and characterized using XRD, SEM, and IR spectroscopy. The NZ, FNZ and activated charcoal were then tested using ASTM method F726-12 to validate the oil sorption capacity and TGA was used for the oil selectivity of the adsorbents. The results indicate that FNZ has an improved oil/water adsorption capacity than NZ when functionalized with ester and has a comparable capacity with activated charcoal.

  9. Modeling butadiene adsorption on oxidized graphene surface using density functional theory

    Science.gov (United States)

    Akimenko, Ju. Y.; Akimenko, S. S.; Gorbunov, V. A.

    2017-08-01

    In this paper, the process of chemisorption of cis-butadiene rubber on the surface of oxidized graphene was studied using the density functional theory. The polymer is interacting to a quinone group, an oxygen bridge, and an OH group which was differently located on the surface of the graphene sheet. Based on the calculated value of ΔG298, the possibility of spontaneous formation of the bond between butadiene rubber and these functional groups was estimated. The features of the temperature dependence of the change in free Gibbs energy for thermodynamically possible coupled systems are considered.

  10. Amino-functionalized green fluorescent carbon dots as surface energy transfer biosensors for hyaluronidase.

    Science.gov (United States)

    Liu, Siyu; Zhao, Ning; Cheng, Zhen; Liu, Hongguang

    2015-04-21

    Amino-functionalized fluorescent carbon dots have been prepared by hydrothermal treatment of glucosamine with excess pyrophosphate. The produced carbon dots showed stabilized green emission fluorescence at various excitation wavelengths and pH environments. Herein, we demonstrate the surface energy transfer between the amino-functionalized carbon dots and negatively charged hyaluronate stabilized gold nanoparticles. Hyaluronidase can degrade hyaluronate and break down the hyaluronate stabilized gold nanoparticles to inhibit the surface energy transfer. The developed fluorescent carbon dot/gold nanoparticle system can be utilized as a biosensor for sensitive and selective detection of hyaluronidase by two modes which include fluorescence measurements and colorimetric analysis.

  11. Aminopropyltriethoxysilane-mediated surface functionalization of hydroxyapatite nanoparticles: synthesis, characterization, and in vitro toxicity assay

    Directory of Open Access Journals (Sweden)

    Wang S

    2011-12-01

    Full Text Available Shige Wang1, Shihui Wen2, Mingwu Shen2, Rui Guo2, Xueyan Cao2, Jianhua Wang3, Xiangyang Shi1,2,41State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, 2College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, 3Department of Biochemistry and Molecular Cell Biology, School of Medicine, Shanghai Jiao Tong University, Shanghai, People's Republic of China; 4Centro de Química da Madeira, Universidade da Madeira, Campus da Penteada, Funchal, PortugalBackground: We report on aminopropyltriethoxysilane (APTS-mediated surface modification of nanohydroxyapatite with different surface functional groups for potential biomedical applications. In this study, nanohydroxyapatite covalently linked with APTS (n-HA-APTS was reacted with acetic anhydride or succinic anhydride to produce neutralized (n-HA-APTS.Ac or negatively charged (n-HA-APTS.SAH nanohydroxyapatite, respectively. Nanohydroxyapatite formed with amine, acetyl, and carboxyl groups was extensively characterized using Fourier transform infrared spectroscopy, transmission electron microscopy, 1H nuclear magnetic resonance spectroscopy, X-ray diffraction, inductively coupled plasma-atomic emission spectroscopy, and zeta potential measurements.Results: In vitro 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide colorimetric assay revealed that the slight toxicity of the amine-functionalized n-HA-APTS could be eliminated by post-functionalization of APTS amines to form acetyl and carboxyl groups. Blood compatibility assessment demonstrated that the negligible hemolytic activity of the pristine nanohydroxyapatite particles did not appreciably change after APTS-mediated surface functionalization.Conclusion: APTS-mediated functionalization of nanohydroxyapatite with different surface groups may be useful for further functionalization of nanohydroxyapatite with biologically active materials, thereby providing possibilities for a broad range of

  12. The thumb carpometacarpal joint: curvature morphology of the articulating surfaces, mathematical description and mechanical functioning.

    Science.gov (United States)

    Dathe, Henning; Dumont, Clemens; Perplies, Rainer; Fanghänel, Jochen; Kubein-Meesenburg, Dietmar; Nägerl, Hans; Wachowski, Martin M

    2016-01-01

    The purpose is to present a mathematical model of the function of the thumb carpometacarpal joint (TCMCJ) based on measurements of human joints. In the TCMCJ both articulating surfaces are saddle-shaped. The aim was to geometrically survey the shapes of the articulating surfaces using precise replicas of 28 TCMCJs. None of these 56 articulating surfaces did mathematically extend the differential geometrical neighbourhood around the main saddle point so that each surface could be characterised by three main parameters: the two extreme radii of curvature in the main saddle point and the angle between the saddles' asymptotics (straight lines). The articulating surfaces, when contacting at the respective main saddle points, are incongruent. Hence, the TCMCJ has functionally five kinematical degrees of freedom (DOF); two DOF belong to flexion/extension, two to ab-/adduction. These four DOF are controlled by the muscular apparatus. The fifth DOF, axial rotation, cannot be adjusted but stabilized by the muscular apparatus so that physiologically under compressive load axial rotation does not exceed an angle of approximately ±3°. The TCMCJ can be stimulated by the muscular apparatus to circumduct. The mechanisms are traced back to the curvature incongruity of the saddle surfaces. Hence we mathematically proved that none of the individual saddle surfaces can be described by a quadratic saddle surface as is often assumed in literature. We derived an algebraic formula with which the articulating surfaces in the TCMCJ can be quantitatively described. This formula can be used to shape the articulating surfaces in physiologically equivalent TCMCJ-prostheses.

  13. Determination of the transfer function for optical surface topography measuring instruments—a review

    Science.gov (United States)

    Foreman, Matthew R.; Giusca, Claudiu L.; Coupland, Jeremy M.; Török, Peter; Leach, Richard K.

    2013-05-01

    A significant number of areal surface topography measuring instruments, largely based on optical techniques, are commercially available. However, implementation of optical instrumentation into production is currently difficult due to the lack of understanding of the complex interaction between the light and the component surface. Studying the optical transfer function of the instrument can help address this issue. Here a review is given of techniques for the measurement of optical transfer functions. Starting from the basis of a spatially coherent, monochromatic confocal scanning imaging system, the theory of optical transfer functions in three-dimensional (3D) imaging is presented. Further generalizations are reviewed allowing the extension of the theory to the description of conventional and interferometric 3D imaging systems. Polychromatic transfer functions and surface topography measurements are also discussed. Following presentation of theoretical results, experimental methods to measure the optical transfer function of each class of system are presented, with a focus on suitable methods for the establishment of calibration standards in 3D imaging and surface topography measurements.

  14. Determination of the transfer function for optical surface topography measuring instruments—a review

    International Nuclear Information System (INIS)

    Foreman, Matthew R; Török, Peter; Giusca, Claudiu L; Leach, Richard K; Coupland, Jeremy M

    2013-01-01

    A significant number of areal surface topography measuring instruments, largely based on optical techniques, are commercially available. However, implementation of optical instrumentation into production is currently difficult due to the lack of understanding of the complex interaction between the light and the component surface. Studying the optical transfer function of the instrument can help address this issue. Here a review is given of techniques for the measurement of optical transfer functions. Starting from the basis of a spatially coherent, monochromatic confocal scanning imaging system, the theory of optical transfer functions in three-dimensional (3D) imaging is presented. Further generalizations are reviewed allowing the extension of the theory to the description of conventional and interferometric 3D imaging systems. Polychromatic transfer functions and surface topography measurements are also discussed. Following presentation of theoretical results, experimental methods to measure the optical transfer function of each class of system are presented, with a focus on suitable methods for the establishment of calibration standards in 3D imaging and surface topography measurements. (topical review)

  15. Effects of surface functionalization on the electronic and structural properties of carbon nanotubes: A computational approach

    Science.gov (United States)

    Ribeiro, M. S.; Pascoini, A. L.; Knupp, W. G.; Camps, I.

    2017-12-01

    Carbon nanotubes (CNTs) have important electronic, mechanical and optical properties. These features may be different when comparing a pristine nanotube with other presenting its surface functionalized. These changes can be explored in areas of research and application, such as construction of nanodevices that act as sensors and filters. Following this idea, in the current work, we present the results from a systematic study of CNT's surface functionalized with hydroxyl and carboxyl groups. Using the entropy as selection criterion, we filtered a library of 10k stochastically generated complexes for each functional concentration (5, 10, 15, 20 and 25%). The structurally related parameters (root-mean-square deviation, entropy, and volume/area) have a monotonic relationship with functionalization concentration. Differently, the electronic parameters (frontier molecular orbital energies, electronic gap, molecular hardness, and electrophilicity index) present and oscillatory behavior. For a set of concentrations, the nanotubes present spin polarized properties that can be used in spintronics.

  16. Modeling of edge effect in subaperture tool influence functions of computer controlled optical surfacing.

    Science.gov (United States)

    Wan, Songlin; Zhang, Xiangchao; He, Xiaoying; Xu, Min

    2016-12-20

    Computer controlled optical surfacing requires an accurate tool influence function (TIF) for reliable path planning and deterministic fabrication. Near the edge of the workpieces, the TIF has a nonlinear removal behavior, which will cause a severe edge-roll phenomenon. In the present paper, a new edge pressure model is developed based on the finite element analysis results. The model is represented as the product of a basic pressure function and a correcting function. The basic pressure distribution is calculated according to the surface shape of the polishing pad, and the correcting function is used to compensate the errors caused by the edge effect. Practical experimental results demonstrate that the new model can accurately predict the edge TIFs with different overhang ratios. The relative error of the new edge model can be reduced to 15%.

  17. Using extremely halophilic bacteria to understand the role of surface charge and surface hydration in protein evolution, folding, and function

    Science.gov (United States)

    Hoff, Wouter; Deole, Ratnakar; Osu Collaboration

    2013-03-01

    Halophilic Archaea accumulate molar concentrations of KCl in their cytoplasm as an osmoprotectant, and have evolved highly acidic proteomes that only function at high salinity. We examine osmoprotection in the photosynthetic Proteobacteria Halorhodospira halophila. We find that H. halophila has an acidic proteome and accumulates molar concentrations of KCl when grown in high salt media. Upon growth of H. halophila in low salt media, its cytoplasmic K + content matches that of Escherichia coli, revealing an acidic proteome that can function in the absence of high cytoplasmic salt concentrations. These findings necessitate a reassessment of two central aspects of theories for understanding extreme halophiles. We conclude that proteome acidity is not driven by stabilizing interactions between K + ions and acidic side chains, but by the need for maintaining sufficient solvation and hydration of the protein surface at high salinity through strongly hydrated carboxylates. We propose that obligate protein halophilicity is a non-adaptive property resulting from genetic drift in which constructive neutral evolution progressively incorporates weakly stabilizing K + binding sites on an increasingly acidic protein surface.

  18. Simple preparation of thiol-ene particles in glycerol and surface functionalization by thiol-ene chemistry (TEC) and surface chain transfer free radical polymerization (SCT-FRP)

    DEFF Research Database (Denmark)

    Hoffmann, Christian; Chiaula, Valeria; Pinelo, Manuel

    2018-01-01

    functionalization of excess thiol groups via photochemical thiol-ene chemistry (TEC) resulting in a functional monolayer. In addition, surface chain transfer free radical polymerization (SCT-FRP) was used for the first time to introduce a thicker polymer layer on the particle surface. The application potential...

  19. Adjustment of surface chemical and physical properties with functionalized polymers to control cell adhesion

    Science.gov (United States)

    Zhou, Zhaoli

    Cell-surface interaction is crucial in many cellular functions such as movement, growth, differentiation, proliferation and survival. In the present work, we have developed several strategies to design and prepare synthetic polymeric materials with selected cues to control cell attachment. To promote neuronal cell adhesion on the surfaces, biocompatible, non-adhesive PEG-based materials were modified with neurotransmitter acetylcholine functionalities to produce hydrogels with a range of porous structures, swollen states, and mechanical strengths. Mice hippocampal cells cultured on the hydrogels showed differences in number, length of processes and exhibited different survival rates, thereby highlighting the importance of chemical composition and structure in biomaterials. Similar strategies were used to prepare polymer brushes to assess how topographical cues influence neuronal cell behaviors. The brushes were prepared using the "grown from" method through surface-initiated atom transfer radical polymerization (SI-ATRP) reactions and further patterned via UV photolithography. Protein absorption tests and hippocampal neuronal cell culture of the brush patterns showed that both protein and neuronal cells can adhere to the patterns and therefore can be guided by the patterns at certain length scales. We also prepared functional polymers to discourage attachment of undesirable cells on the surfaces. For example, we synthesized PEG-perfluorinated alkyl amphiphilic surfactants to modify polystyrene-block-poly(ethylene-ran-butylene)- block-polyisoprene (SEBI or K3) triblock copolymers for marine antifouling/fouling release surface coatings. Initial results showed that the polymer coated surfaces can facilitate removal of Ulva sporelings on the surfaces. In addition, we prepared both bioactive and dual functional biopassive/bioactive antimicrobial coatings based on SEBI polymers. Incubating the polymer coated surfaces with gram-positive bacteria (S. aureus), gram

  20. Study of carboxylic functionalization of polypropylene surface using the underwater plasma technique

    Science.gov (United States)

    Joshi, R. S.; Friedrich, J. F.; Wagner, M. H.

    2009-08-01

    Non-equilibrium solution plasma treatment of polymer surfaces in water offers the possibility of more dense and selective polymer surface functionalization in comparison to the well-known and frequently used low-pressure oxygen plasma. Functional groups are introduced when the polymer surface contacts the plasma moderated solution especially water solutions. The emission of ions, electrons, energy-rich neutrals and complexes, produced by the ion avalanche are limited by quenching, with the aid of the ambient water phase. The UV-radiation produced in plasma formation also helps to moderate the reaction solution further by producing additional excited, ionized/dissociated molecules. Thus, monotype functional groups equipped polymer surfaces, preferably OH groups, originating from the dissociated water molecules, could be produced more selectively. An interesting feature of the technique is its flexibility to use a wide variety of additives in the water phase. Another way to modify polymer surfaces is the deposition of plasma polymers carrying functional groups as carboxylic groups used in this work. Acetic acid, acrylic acid, maleic and itaconic acid were used as additive monomers. Acetic acid is not a chemically polymerizing monomer but it could polymerize by monomer/molecular fragmentation and recombination to a cross linked layer. The other monomers form preferably water-soluble polymers on a chemical way. Only the fragmented fraction of these monomers could form an insoluble coating by cross linking to substrate. The XPS analysis was used to track the alterations in -O-CO- bond percentage on the PP surface. To identify the -COOH groups on substrate surface unambiguously, which have survived the plasma polymerization process, the derivatization with trifluoroethanol was performed.

  1. Assembly, Structure, and Functionality of Metal-Organic Networks and Organic Semiconductor Layers at Surfaces

    Science.gov (United States)

    Tempas, Christopher D.

    Self-assembled nanostructures at surfaces show promise for the development of next generation technologies including organic electronic devices and heterogeneous catalysis. In many cases, the functionality of these nanostructures is not well understood. This thesis presents strategies for the structural design of new on-surface metal-organic networks and probes their chemical reactivity. It is shown that creating uniform metal sites greatly increases selectivity when compared to ligand-free metal islands. When O2 reacts with single-site vanadium centers, in redox-active self-assembled coordination networks on the Au(100) surface, it forms one product. When O2 reacts with vanadium metal islands on the same surface, multiple products are formed. Other metal-organic networks described in this thesis include a mixed valence network containing Pt0 and PtII and a network where two Fe centers reside in close proximity. This structure is stable to temperatures >450 °C. These new on-surface assemblies may offer the ability to perform reactions of increasing complexity as future heterogeneous catalysts. The functionalization of organic semiconductor molecules is also shown. When a few molecular layers are grown on the surface, it is seen that the addition of functional groups changes both the film's structure and charge transport properties. This is due to changes in both first layer packing structure and the pi-electron distribution in the functionalized molecules compared to the original molecule. The systems described in this thesis were studied using high-resolution scanning tunneling microscopy, non-contact atomic force microscopy, and X-ray photoelectron spectroscopy. Overall, this work provides strategies for the creation of new, well-defined on-surface nanostructures and adds additional chemical insight into their properties.

  2. Voltammetry and Electrocatalysis of Achrornobacter Xylosoxidans Copper Nitrite Reductase on Functionalized Au(111)-Electrode Surfaces

    DEFF Research Database (Denmark)

    Welinder, Anna C.; Zhang, Jingdong; Hansen, Allan G.

    2007-01-01

    positively charged and electrostatically neutral, hydrophobic and hydrophilic, aliphatic and aromatic, and variable-length micro-environments, as well as their combinations. Optimal conditions for enzyme function seems to be a combination of hydrophobic and hydrophilic surface linker properties, which can...... lead to close to complete non-catalytic monolayer interfacial electron transfer function and electrocatalysis with activity approaching enzyme activity in homogeneous solution. Thiophenol (combined hydrophobic stacking and interdispersed water molecules), 4-methyl-thiophenol (hydrophobic and water...

  3. Zeta function of self-adjoint operators on surfaces of revolution

    International Nuclear Information System (INIS)

    Lu, Tianshi; Jeffres, Thalia; Kirsten, Klaus

    2015-01-01

    In this article we analyze the zeta function for the Laplace operator on a surface of revolution. A variety of boundary conditions, separated and unseparated, are considered. Formulas for several residues and values of the zeta function as well as for the determinant of the Laplacian are obtained. The analysis is based upon contour integration techniques in combination with a WKB analysis of solutions of related initial value problems. (paper)

  4. Influencia del Estado de Oxidación del Ión Cobalto en la Estabilidad de Electrodos Modificados con Monocapas SAM-TOA-ANTA-Con+-HRP-NHis.

    Directory of Open Access Journals (Sweden)

    Pedro R. Matheus*

    Full Text Available Influence of state oxidation of cobalt ion in the stability electrodes modified with monolayers SAM-TOA-ANTA-Con+-HRP-NHis. Quartz Crystal Microbalance (QCM was used to investigate the adsorption of the HRP-NHis enzyme (horseradish peroxidase, which was modified by the addition of a tail of six histidine on its extreme N-terminal. The QCM operating at flow of 0.025 mL min-1 on a crystal whose gold electrode was modified with monolayers of SAM-TOA-ANTA-Co2+ and SAM-TOA-ANTA -Co3+. The oxidize form was obtained from the electrochemical oxidation of a monolayer of SAM-TOA-ANTA-Co2+. The results suggest that the HRP-NHis is attached to both monolayers in a similar way; on the contrary, the desortion of the attached protein is dramatically different. Thus, whereas the ligand-Co2+ bonds are reversible, which allows that the anchored protein is easily replaced by imidazol molecules. The 3+ oxidation state of the metal does not allow the interchange of protein by the imidazol molecules.

  5. Microstructured Polymer Blend Surfaces Produced by Spraying Functional Copolymers and Their Blends.

    Science.gov (United States)

    Vargas-Alfredo, Nelson; Rodríguez Hernández, Juan

    2016-05-31

    We described the fabrication of functional and microstructured surfaces from polymer blends by spray deposition. This simple technique offers the possibility to simultaneously finely tune the microstructure as well as the surface chemical composition. Whereas at lower polymer concentration, randomly distributed surface micropatterns were observed, an increase of the concentration leads to significant changes on these structures. On the one hand, using pure homopolystyrene fiber-like structures were observed when the polymer concentration exceeded 30 mg/mL. Interestingly, the incorporation of 2,3,4,5,6-pentafluorostyrene changed the morphology, and, instead of fibers, micrometer size particles were identified at the surface. These fluorinated microparticles provide superhydrophobic properties leading to surfaces with contact angles above 165°. Equally, in addition to the microstructures provided by the spray deposition, the use of thermoresponsive polymers to fabricate interfaces with responsive properties is also described. Contact angle measurements revealed variations on the surface wettability upon heating when blends of polystyrene and polystyrene- b -poly(dimethylaminoethyl methacrylate) are employed. Finally, the use of spraying techniques to fabricate gradient surfaces is proposed. Maintaining a constant orientation, the surface topography and thus the contact angle varies gradually from the center to the edge of the film depending on the spray angle.

  6. Doping effects of surface functionalization on graphene with aromatic molecule and organic solvents

    Science.gov (United States)

    Wu, Guangfu; Tang, Xin; Meyyappan, M.; Lai, King Wai Chiu

    2017-12-01

    Aromatic molecule functionalization plays a key role in the development of graphene field-effect transistors (G-FETs) for bio-detection. We have investigated the doping effects of surface functionalization and its influence on the carrier mobility of graphene. The aromatic molecule (1-pyrenebutanoic acid succinimidyl ester, PBASE), which is widely used as a linker to anchor bio-probes, was employed here to functionalize graphene. Dimethyl formamide (DMF) and methanol (CH3OH) were used as two solvents to dissolve PBASE. Raman spectra showed that both PBASE and these two solvents imposed doping effects on graphene. The PBASE was stably immobilized on the graphene surface, which was confirmed by the new peak at around 1623.5 cm-1 and the disordered D peak at 1350 cm-1. Electrical measurements and Fermi level shift analysis further revealed that PBASE imposes a p-doping effect while DMF and CH3OH impose an n-doping effect. More importantly, CH3OH causes a smaller reduction in the carrier mobility of G-FETs (from 1095.6 cm2/V s to 802.4 cm2/V s) than DMF (from 1640.4 cm2/V s to 5.0 cm2/V s). Therefore, CH3OH can be regarded as a better solvent for the PBASE functionalization. This careful study on the influence of organic solvents on graphene during PBASE functionalization process provides an effective approach to monitor the surface functionalization of graphene.

  7. Highly Hydrophilic Thin-Film Composite Forward Osmosis Membranes Functionalized with Surface-Tailored Nanoparticles

    KAUST Repository

    Tiraferri, Alberto

    2012-09-26

    Thin-film composite polyamide membranes are state-of-the-art materials for membrane-based water purification and desalination processes, which require both high rejection of contaminants and high water permeabilities. However, these membranes are prone to fouling when processing natural waters and wastewaters, because of the inherent surface physicochemical properties of polyamides. The present work demonstrates the fabrication of forward osmosis polyamide membranes with optimized surface properties via facile and scalable functionalization with fine-tuned nanoparticles. Silica nanoparticles are coated with superhydrophilic ligands possessing functional groups that impart stability to the nanoparticles and bind irreversibly to the native carboxyl moieties on the membrane selective layer. The tightly tethered layer of nanoparticles tailors the surface chemistry of the novel composite membrane without altering the morphology or water/solute permeabilities of the membrane selective layer. Surface characterization and interfacial energy analysis confirm that highly hydrophilic and wettable membrane surfaces are successfully attained. Lower intermolecular adhesion forces are measured between the new membrane materials and model organic foulants, indicating the presence of a bound hydration layer at the polyamide membrane surface that creates a barrier for foulant adhesion. © 2012 American Chemical Society.

  8. ADSORPTION OF ASSOCIATING FLUIDS AT ACTIVE SURFACES: A DENSITY FUNCTIONAL THEORY

    Directory of Open Access Journals (Sweden)

    S.Tripathi

    2003-01-01

    Full Text Available We present a density functional theory (DFT to describe adsorption in systems where molecules of associating fluids can bond (or associate with discrete, localized functional groups attached to the surfaces, in addition to other fluid molecules. For such systems as water adsorbing on activated carbon, silica, clay minerals etc. this is a realistic model to account for surface heterogeneity rather than using a continuous smeared surface-fluid potential employed in most of the theoretical works on adsorption on heterogeneous surfaces. Association is modelled within the framework of first order thermodynamic perturbation theory (TPT1. The new theory accurately predicts the distribution of bonded and non-bonded species and adsorption behavior under various conditions of bulk pressure, surface-fluid and fluid-fluid association strengths. Competition between the surface-fluid and fluid-fluid association is analyzed for fluids with multiple association sites and its impact on adsorption is discussed. The theory, supported by simulations demonstrates that the extent and the nature of adsorption (e.g. monolayer vary with the number of association sites on the fluid molecules.

  9. Surface functionalization of magnetite nanoparticle: A new approach using condensation of alkoxysilanes

    Science.gov (United States)

    Rodriguez, A. F. R.; Costa, T. P.; Bini, R. A.; Faria, F. S. E. D. V.; Azevedo, R. B.; Jafelicci, M.; Coaquira, J. A. H.; Martínez, M. A. R.; Mantilla, J. C.; Marques, R. F. C.; Morais, P. C.

    2017-09-01

    In this study we report on successful production of two samples (BR15 and BR16) comprising magnetite (Fe3O4) nanoparticles ( 10 nm) surface-functionalized via hydrolysis and condensation of alkoxysilane agents, namely 3-aminopropyl-trimethoxisilane (APTS) and N-propyl-trimethoxisilane (NPTS). The as-produced samples were characterized using transmission electron microscopy (TEM), x-ray diffraction (XRD), magnetization measurements (5 K and 300 K hysteresis cycles and zero field-cooled/field-cooled measurements), and Mössbauer spectroscopy (77 and 297 K). The Mössbauer data supported the model picture of a core-shell magnetite-based system. This material system shows shell properties influenced by the surface-coating design, either APTS-coated (BR15) or APTS+NPTS-coated (sample BR16). Analyses of the Mössbauer spectra indicates that the APTS-coated sample presents Fe(III)-rich core and Fe(II)-rich shell with strong hyperfine field; whereas, the APTS+NPTS-coated sample leads to a mixture of two main nanostructures, one essentially surface-terminated with APTS whereas the other surface-terminated with NPTS, both presenting weak hyperfine fields compared with the single surface-coated sample. Magnetization measurements support the core-shell picture built from the analyses of the Mössbauer data. Our findings emphasize the capability of the Mössbauer spectroscopy in assessing subtle differences in surface-functionalized iron-based core-shell nanostructures.

  10. Towards Dynamic Control of Wettability by Using Functionalized Altitudinal Molecular Motors on Solid Surfaces

    NARCIS (Netherlands)

    London, Gabor; Chen, Kuang-Yen; Carroll, Gregory T.; Feringa, Ben L.

    2013-01-01

    We report the synthesis of altitudinal molecular motors that contain functional groups in their rotor part. In an approach to achieve dynamic control over the properties of solid surfaces, a hydrophobic perfluorobutyl chain and a relatively hydrophilic cyano group were introduced to the rotor part

  11. Tailor-Made Pore Surface Engineering in Covalent Organic Frameworks: Systematic Functionalization for Performance Screening

    NARCIS (Netherlands)

    Huang, N.; Krishna, R.; Jiang, D.

    2015-01-01

    Imine-linked covalent organic frameworks (COFs) were synthesized to bear content-tunable, accessible, and reactive ethynyl groups on the walls of one-dimensional pores. These COFs offer an ideal platform for pore-wall surface engineering aimed at anchoring diverse functional groups ranging from

  12. Microgel-based surface modifying system for stimuli-responsive functional finishing of cotton

    NARCIS (Netherlands)

    Kulkarni, A.N.; Tourrette, A.; Warmoeskerken, Marinus; Jocic, D.

    2010-01-01

    An innovative strategy for functional finishing of textile materials is based on the incorporation of a thin layer of surface modifying systems (SMS) in the form of stimuli-sensitive microgels or hydrogels. Since the copolymerization of poly(N-isopropylacrylamide) with an ionizable polymer, such as

  13. Examination of the wind speed limit function in the Rothermel surface fire spread model

    Science.gov (United States)

    Patricia L. Andrews; Miguel G. Cruz; Richard C. Rothermel

    2013-01-01

    The Rothermel surface fire spread model includes a wind speed limit, above which predicted rate of spread is constant. Complete derivation of the wind limit as a function of reaction intensity is given, along with an alternate result based on a changed assumption. Evidence indicates that both the original and the revised wind limits are too restrictive. Wind limit is...

  14. Highly surface functionalized carbon nano-onions for bright light bioimaging

    International Nuclear Information System (INIS)

    Frasconi, Marco; Maffeis, Viviana; Bartelmess, Juergen; Giordani, Silvia; Echegoyen, Luis

    2015-01-01

    Carbon-based nanomaterials functionalized with fluorescent and water-soluble groups have emerged as platforms for biological imaging because of their low toxicity and ability to be internalized by cells. The development of imaging probes based on carbon nanomaterials for biomedical studies requires the understanding of their biological response as well as the efficient and safety exposition of the nanomaterial to the cell compartment where it is designed to operate. Here, we present a fluorescent probe based on surface functionalized carbon nano-onions (CNOs) for biological imaging. The modification of CNOs by chemical oxidation of the defects on the outer shell of these carbon nanoparticles results in an extensive surface functionalization with carboxyl groups. We have obtained fluorescently labelled CNOs by a reaction involving the amide bond formation between fluoresceinamine and the carboxylic acids groups on the surface of the CNOs. The functionalized CNOs display high emission properties and dispersability in water due to the presence of high surface coverage of carboxylic acid groups that translate in an efficient fluorescent probe for in vitro imaging of HeLa cells, without significant cytotoxicity. The resulting nanomaterial represents a promising platform for biological imaging applications due to the high dispersability in water, its efficient internalization by cancer cells and localization in specific cell compartments. (paper)

  15. Surface Functionalization of Epoxy-Resist- Based Microcantilevers with Iron Oxide Nanocrystals

    DEFF Research Database (Denmark)

    Ingrosso, Chiara; Sardella, E.; Keller, Stephan Sylvest

    2010-01-01

    A functionalization procedure is integrated in the fabrication of micromechanical SU-8 cantilevers in order to chemically bind organic-capped Fe2O3 NCs at the photoresist surface, under visible light, ambient atmosp here and room temperature. The achieved highly interconnected NC multilayer network...

  16. Nano-structured and functionalized surfaces for cytocompatibility improvement and bactericidal action.

    Science.gov (United States)

    Slepicka, Petr; Kasalkova, Nikola Slepickova; Siegel, Jakub; Kolska, Zdenka; Bacakova, Lucie; Svorcik, Vaclav

    2015-11-01

    The field of material surface modification with the aim of biomaterial construction involves several approaches of treatments that allow the preparation of materials, which positively influence adhesion of cells and their proliferation and thus aid and improve tissue formation. Modified materials have a surface composition and morphology intended to interact with biological systems and cellular functions. Not only surface chemistry has an effect on material biological response, surface structures of different morphology can be constructed to guide a desirable biological outcome. Nano-patterned material surfaces have been tested with the aim of how surface geometry and physical properties on a micro- and nano-scale can affect cellular response and influence cell adhesion and proliferation. Biological functionality of solid state substrates was significantly improved by the irradiation of material with plasma discharge or laser treatment. Commonly used "artificial" polymers (e.g. polyethylene (PE), polystyrene (PS), polytetrafluoroethylene (PTFE), polyethylene terephthalate (PET), polyethylene naphthalate (PEN)) and biopolymers (e.g. Poly-l-Lactic acid (PLLA), polymethylpentene (PMP)) were treated with aim of biocompatibility improvement. The treatment of polymer/biopolymer substrates leads to formation of ripple or wrinkle-like structures, supported also with heat treatment or other subsequent surface processing. Several types of chemically different substances (e.g. metal or carbon nano-particles, proteins) were grafted onto material surfaces or built into material structures by different processes. Surface physico-chemical properties (e.g. chemistry, charge, morphology, wettability, electrical conductivity, optical and mechanical properties) of treated surfaces were determined. The enhancement of adhesion and proliferation of cells on modified substrates was investigated in vitro. Bactericidal action of noble metal nano-particles (e.g. Au, Ag) on polymers was

  17. ENCAPSULATION OF HORSERADISH PEROXIDASE-GLUCOSE OXIDASE (HRP-GOx IN SILICA AQUAGEL SYNTHESIZED FROM RICE HULL ASH FOR ENZYMATIC REACTION OF GLUCOSE

    Directory of Open Access Journals (Sweden)

    Nuryono Nuryono

    2010-06-01

    Full Text Available In recent years, the sol-gel technique has attracted increasing interest as a unique approach to immobilize biomolecules for bioanalytical applications as well as biochemical and biophysical studies. In this research, encapsulation of Horseradish peroxidase-Glucose oxidase (HRP-GOx enzymes in silica aquagel from rice hull ash by sol-gel process has been carried out. In addition, the effect of several parameters (weight ratio of HRP to GOx, pH, temperature, sodium ion concentration on enzyme activity was studied, as well. Rice hull ash, which was produced by ashing at 700 °C, was extracted it's silika by NaOH solution 1 M at 100 °C for two hours to produce sodium silikate (Na2SiO3 solution. The Na2SiO3 solution with pH of 13 was added with a strong cation exchanger resin, to produce sol solution with the pH of 4. Encapsulation was emphasized by mixing sol solution and phosphate buffer pH 7 containing HRP-GOx solution at volume ratio of buffer to sol solution 1:5. The mixture was transferred into 96-microwell plate and was aged for 24 hours. Enzymatic reaction was carried out by adding chromogenic solution of phenol and 4-aminoantipyrine (4-AAP and b-D-glucose solution (as substrate into the microwell. Enzymatic activity was examined by measuring absorbance of product solution at 490 nm with ELISA reader. Result of enzymatic activity for encapsulated enzymes (SGE was compared to that for free enzymes (EB. Results showed that at the investigated condition, HRP-GOx enzymes gave high activity at weight ratio of HRP to GOx 10:1 and pH 7 for both SGE and EB. Encapsulation caused the enzymes activity decrease to 53.0±0.2 %. However, SGE was observed to be more stable on pH and temperature changes than EB. Study on the effect of sodium concentration showed that the increase of sodium concentration from 0.10 to 0.37 M decreased the enzymatic activity to 56±0.2%. Reusability test showed that the synthesized SGE was reusable with activity decrease of 60

  18. The insect-trapping rim of Nepenthes pitchers: surface structure and function.

    Science.gov (United States)

    Bauer, Ulrike; Federle, Walter

    2009-11-01

    Carnivorous pitcher plants of the genus Nepenthes capture prey with a pitfall trap that relies on a micro-structured, slippery surface. The upper pitcher rim (peristome) is fully wettable and causes insects to slip by aquaplaning on a thin water film. The high wettability of the peristome is probably achieved by a combination of hydrophilic surface chemistry, surface roughness and the presence of hygroscopic nectar. Insect foot attachment could be prevented by the delayed drainage of the thin water film between the adhesive pad and the surface. Drainage should be faster for insects with a hairy adhesive system; however, they slip equally on the wet peristome. Therefore the stability of the water film against dewetting appears to be the key factor for aquaplaning. New experimental techniques may help to clarify the detailed function of the pitcher plant peristome and to explore its potential for biomimetic applications.

  19. Surface functionalized nanofibrillar cellulose (NFC) film as a platform for immunoassays and diagnostics.

    Science.gov (United States)

    Orelma, Hannes; Filpponen, Ilari; Johansson, Leena-Sisko; Osterberg, Monika; Rojas, Orlando J; Laine, Janne

    2012-12-01

    We introduce a new method to modify films of nanofibrillated cellulose (NFC) to produce non-porous, water-resistant substrates for diagnostics. First, water resistant NFC films were prepared from mechanically disintegrated NFC hydrogel, and then their surfaces were carboxylated via TEMPO-mediated oxidation. Next, the topologically functionalized film was activated via EDS/NHS chemistry, and its reactivity verified with bovine serum albumin and antihuman IgG. The surface carboxylation, EDC/NHS activation and the protein attachment were confirmed using quartz crystal microbalance with dissipation, contact angle measurements, conductometric titrations, X-ray photoelectron spectroscopy and fluorescence microscopy. The surface morphology of the prepared films was investigated using confocal laser scanning microscopy and atomic force microscopy. Finally, we demonstrate that antihuman IgG can be immobilized on the activated NFC surface using commercial piezoelectric inkjet printing.

  20. Grain boundaries at the surface of consolidated MgO nanocrystals and acid-base functionality.

    Science.gov (United States)

    Vingurt, Dima; Fuks, David; Landau, Miron V; Vidruk, Roxana; Herskowitz, Moti

    2013-09-21

    The increase of the surface basicity-acidity of MgO material by factors of 1.8-3.0 due to consolidation of its nanocrystals was demonstrated by the indicator titration. It was shown that the parallel increase of surface acidity and basicity is attributed to the formation of grain boundaries (GB) after MgO aerogel densification. A simple model predicting the increase of surface acidity-basicity of MgO that correlates with the results of direct measurements was proposed. The model is based on the study of the fine atomic structure at GB surface areas in consolidated MgO nanocrystals in the framework of Density Functional Theory. It is found that the displacements of coordinatively unsaturated surface ions near the GB are significant at the distances ~3-4 atomic layers from the geometrical contact plane between nanocrystals. The detailed analysis of atomic positions inside GB demonstrated the coordination deficiency of surface atoms at the GB areas leading to the formation of stretched bonds and to creation of low coordinated surface ions due to splitting of coordination numbers of surface atoms belonging to GB areas. Density of states for electrons shows the existence of additional states in the band gap close to the bottom of the conduction band. The adsorption energy of CO2 molecules atop oxygen atoms exposed at surface GB areas is of the same order of magnitude as that reported for oxygen atoms at crystallographic edges and corners of MgO crystals. It provides additional options for bonding of molecules at the surface of nanocrystalline MgO increasing the adsorption capacity and catalytic activity.

  1. Synthesis of nano-hydroxyapatite and its rapid mediated surface functionalization by silane coupling agent

    Energy Technology Data Exchange (ETDEWEB)

    Rehman, Sarish, E-mail: kknano@hotmail.com; Khan, Kishwar; Mujahid, Mohammad; Nosheen, Shaneela

    2016-01-01

    In this work, hydroxyapatite (HA) nanorods were synthesized by simple one step wet precipitation method followed by their rapid surface functionalization via aminopropyltriethoxysilane (APTS) to give modified (HA-APTS) product. Functionalized hydroxyapatite (HA-APTS) holds amino groups on their surface that can be further functionalized with other bioactive molecules. The extent of functionalization of HA was studied under three different processing conditions; at room temperature, at 80 °C and under microwave condition (600 W). Three different temperatures have been use for the purpose of comparison between the functionalized products so that we can judge that whether there is any effect of temperature on the final products. In the last we conclude that temperature has no effect. So microwave condition is best to carried out the functionalization in just 5 min. - Highlights: • Extent of functionalization of HA was studied. • Characterized using FTIR spectroscopy, SEM, FESEM, HRTEM, XRD & NMR • n-HA particles were covalently linked with APTS under microwave radiation. • Beneficial from biomedical point of view.

  2. Green's function based finite element formulations for isotropic seepage analysis with free surface

    Directory of Open Access Journals (Sweden)

    Hui Wang

    Full Text Available Abstract A solution procedure using the Green's function based finite element method (FEM is presented for two-dimensional nonlinear steady-state seepage analysis with the presence of free surface in isotropic dams. In the present algorithm, an iteration strategy is designed to convert the over-specified free surface problem to a regular partial differential equation problem. Then, at each iteration step, the Green's function for isotropic linear seepage partial differential equation is employed to construct the element interior water head field, while the conventional shape functions are used for the independent element frame water head field. Then these two independent fields are connected by a double-variable hybrid functional to produce the final solving equation system. By means of the physical definition of Green's function, all two-dimensional element domain integrals in the present algorithm can reduce to one-dimensional element boundary integrals, so that versatile multi-node element is constructed to simplify mesh reconstruction during iteration. Finally, numerical results from the present Green's function based FEM with isotropic Green's function kernels are compared with other numerical results to verify and demonstrate the performance of the present method.

  3. Periodic density functional theory calculations of bulk and the (010 surface of goethite

    Directory of Open Access Journals (Sweden)

    Sparks Donald L

    2008-05-01

    Full Text Available Abstract Background Goethite is a common and reactive mineral in the environment. The transport of contaminants and anaerobic respiration of microbes are significantly affected by adsorption and reduction reactions involving goethite. An understanding of the mineral-water interface of goethite is critical for determining the molecular-scale mechanisms of adsorption and reduction reactions. In this study, periodic density functional theory (DFT calculations were performed on the mineral goethite and its (010 surface, using the Vienna Ab Initio Simulation Package (VASP. Results Calculations of the bulk mineral structure accurately reproduced the observed crystal structure and vibrational frequencies, suggesting that this computational methodology was suitable for modeling the goethite-water interface. Energy-minimized structures of bare, hydrated (one H2O layer and solvated (three H2O layers (010 surfaces were calculated for 1 × 1 and 3 × 3 unit cell slabs. A good correlation between the calculated and observed vibrational frequencies was found for the 1 × 1 solvated surface. However, differences between the 1 × 1 and 3 × 3 slab calculations indicated that larger models may be necessary to simulate the relaxation of water at the interface. Comparison of two hydrated surfaces with molecularly and dissociatively adsorbed H2O showed a significantly lower potential energy for the former. Conclusion Surface Fe-O and (FeO-H bond lengths are reported that may be useful in surface complexation models (SCM of the goethite (010 surface. These bond lengths were found to change significantly as a function of solvation (i.e., addition of two extra H2O layers above the surface, indicating that this parameter should be carefully considered in future SCM studies of metal oxide-water interfaces.

  4. Luminescent Properties of Surface Functionalized BaTiO3 Embedded in Poly(methyl methacrylate

    Directory of Open Access Journals (Sweden)

    Sebastian Requena

    2014-01-01

    Full Text Available As-received BaTiO3 nanopowders of average grain sizes 50 nm and 100 nm were functionalized by (3-aminopropyltriethoxysilane (APTES and mixed with poly(methyl methacrylate/toluene solution. The nanocomposite solution was spin coated on Si substrates to form thin films. The photoluminescence spectrum of the pure powder was composed of a bandgap emission at 3.0 eV and multiple bands centered about 2.5 eV. Surface functionalization of the BaTiO3 powder via APTES increases overall luminescence at room temperature while only enhancing bandgap emission at low-temperature. Polymer coating of the functionalized nanoparticles significantly enhances bandgap emissions while decreasing emissions associated with near-surface lattice distortions at 2.5 eV.

  5. Luminescent Properties of Surface Functionalized BaTiO3 Embedded in Poly(methyl methacrylate)

    Science.gov (United States)

    Requena, Sebastian; Lacoul, Srijan; Strzhemechny, Yuri M.

    2014-01-01

    As-received BaTiO3 nanopowders of average grain sizes 50 nm and 100 nm were functionalized by (3-aminopropyl)triethoxysilane (APTES) and mixed with poly(methyl methacrylate)/toluene solution. The nanocomposite solution was spin coated on Si substrates to form thin films. The photoluminescence spectrum of the pure powder was composed of a bandgap emission at 3.0 eV and multiple bands centered about 2.5 eV. Surface functionalization of the BaTiO3 powder via APTES increases overall luminescence at room temperature while only enhancing bandgap emission at low-temperature. Polymer coating of the functionalized nanoparticles significantly enhances bandgap emissions while decreasing emissions associated with near-surface lattice distortions at 2.5 eV. PMID:28788468

  6. Luminescent Properties of Surface Functionalized BaTiO₃ Embedded in Poly(methyl methacrylate).

    Science.gov (United States)

    Requena, Sebastian; Lacoul, Srijan; Strzhemechny, Yuri M

    2014-01-16

    As-received BaTiO₃ nanopowders of average grain sizes 50 nm and 100 nm were functionalized by (3-aminopropyl)triethoxysilane (APTES) and mixed with poly(methyl methacrylate)/toluene solution. The nanocomposite solution was spin coated on Si substrates to form thin films. The photoluminescence spectrum of the pure powder was composed of a bandgap emission at 3.0 eV and multiple bands centered about 2.5 eV. Surface functionalization of the BaTiO₃ powder via APTES increases overall luminescence at room temperature while only enhancing bandgap emission at low-temperature. Polymer coating of the functionalized nanoparticles significantly enhances bandgap emissions while decreasing emissions associated with near-surface lattice distortions at 2.5 eV.

  7. Creation of hydrophobic surfaces using a paint containing functionalized oxide particles

    Science.gov (United States)

    Sino, Paul Albert L.; Herrera, Marvin U.; Balela, Mary Donnabelle L.

    2017-05-01

    Hydrophobic surfaces were created by coating various substrates (aluminum sheet, soda-lime glass, silicon carbide polishing paper, glass with double-sided adhesive) with paint containing functionalized oxide particles. The paint was created by functionalizing oxide particles (ground ZnO, TiO2 nanoparticles, or TiO2 microparticles) with fluorosilane molecules in absolute ethanol. Water contact angle of samples shows that the coated substrate becomes hydrophobic (water contact angle ≥ 90°). Among the oxides that were used, ground ZnO yielded contact angle exemplifying superhydrophobicity (water contact angle ≥ 150°). Scanning electron micrograph of paint-containing TiO2 nanoparticles shows rough functionalized oxides structures which probably increase the hydrophobicity of the surface.

  8. O-(carboxymethyl)-chitosan nanofiltration membrane surface functionalized with graphene oxide nanosheets for enhanced desalting properties.

    Science.gov (United States)

    Wang, Jiali; Gao, Xueli; Wang, Jian; Wei, Yi; Li, Zhaokui; Gao, Congjie

    2015-02-25

    A novel O-(carboxymethyl)-chitosan (OCMC) nanofiltration (NF) membrane is developed via surface functionalization with graphene oxide (GO) nanosheets to enhance desalting properties. Using ring-opening polymerization between epoxy groups of GO nanosheets and amino groups of OCMC active layer, GO nanosheets are irreversibly bound to the membrane. The OCMC NF membranes surface-functionalized with GO nanosheets are characterized by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy, contact angle analyzer, and zeta potential analyzer. The membranes exhibit not only higher permeability but also better salt rejections than the pristine membranes and the commercial NF membranes; besides, the desalting properties are enhanced with the concentration of GO nanosheets increasing. Furthermore, the transport mechanism of GO-OCMC NF membranes reveals that the nanoporous structure of GO-OCMC functional layer and size exclusion and electrostatic repulsion of water nanochannels formed by GO nanosheets lead to the membranes possessing enhanced desalting properties.

  9. Titanium Surface Coating with a Laminin-Derived Functional Peptide Promotes Bone Cell Adhesion

    Directory of Open Access Journals (Sweden)

    Seung-Ki Min

    2013-01-01

    Full Text Available Laminin-derived peptide coatings can enhance epithelial cell adhesion to implants, and the positive effect of these peptides on bone cell adhesion has been anticipated. The purpose of this study was to evaluate the improvement in bone cell attachment to and activity on titanium (Ti scaffolds coated with a laminin-derived functional peptide, Ln2-P3 (the DLTIDDSYWYRI motif. Four Ti disc surfaces were prepared, and a human osteosarcoma (HOS cell attachment test was performed to select two candidate surfaces for peptide coating. These two candidates were then coated with Ln2-P3 peptide, a scrambled peptide, or left uncoated to measure cell attachment to each surface, following which one surface was chosen to assess alkaline phosphatase (ALP activity and osteogenic marker gene expression with quantitative real-time PCR. On the commercially pure Ti surface, the Ln2-P3 coating significantly increased cellular ALP activity and the expression levels of ALP and bone sialoprotein mRNA as compared with the scrambled peptide-coated and uncoated surfaces. In conclusion, although further in vivo studies are needed, the findings of this in vitro study indicate that the Ln2-P3-coated implant surface promotes bone cell adhesion, which has clinical implications for reducing the overall treatment time of dental implant therapy.

  10. Investigation of Titan's surface and atmosphere photometric functions using the Cassini/VIMS instrument

    Science.gov (United States)

    Cornet, Thomas; Altobelli, Nicolas; Rodriguez, Sébastien; Maltagliati, Luca; Le Mouélic, Stéphane; Sotin, Christophe; Brown, Robert; Barnes, Jason; Buratti, Bonnie; Baines, Kevin; Clark, Roger; Nicholson, Phillip

    2015-04-01

    After 106 flybys spread over 10 years, the Cassini Visual and Infrared Mapping Spectrometer (VIMS) instrument acquired 33151 hyperspectral cubes pointing at the surface of Titan on the dayside. Despite this huge amount of data available for surface studies, and due to the strong influence of the atmosphere (methane absorption and haze scattering), Titan's surface is only visible with VIMS in 7 spectral atmospheric windows centred at 0.93, 1.08, 1.27, 1.59, 2.01, 2.7-2.8 and 5 microns. Atmospheric scattering and absorption effects dominate Titan's spectrum at wavelengths shorter than 3 microns, while the 5 micron window, almost insensitive to the haze scattering, only presents a reduced atmospheric absorption contribution to the signal recorded by VIMS. In all cases, the recorded I/F represents an apparent albedo, which depends on the atmospheric contributions and the surface photometry at each wavelength. We therefore aim to determine real albedo values for Titan's surface by finding photometric functions for the surface and the atmosphere that could be used as a basis for empirical corrections or Radiative Transfer calculations. After updating the navigation of the VIMS archive, we decomposed the entire VIMS data set into a MySQL relational database gathering the viewing geometry, location, time (season) and I/F (for pure atmosphere and surface-atmosphere images) for each pixel of the 33151 individual VIMS cubes. We then isolated all the VIMS pixels where Titan's surface has been repeatedly imaged at low phase angles (< 20 degrees) in order to characterize phase curves for the surface at 5 microns and for the atmosphere. Among these, the T88 flyby appears noteworthy, with a "Emergence-Phase Function (EPF)"-type observation: 25 cubes acquired during the same flyby, over the same area (close to Tortola Facula, in relatively dark terrains), at a constant incidence and with varying emergence and phase (from 0 to 60 degrees) angles. The data clearly exhibit an increase

  11. Surface-functionalized cockle shell–based calcium carbonate aragonite polymorph as a drug nanocarrier

    Directory of Open Access Journals (Sweden)

    Mohd Abd Ghafar SL

    2017-05-01

    Full Text Available Syairah Liyana Mohd Abd Ghafar,1 Mohd Zobir Hussein,2 Yaya Rukayadi,1,3 Md Zuki Abu Bakar Zakaria1,4 1Institute of Bioscience, 2Institute of Advance Technology, 3Department of Food Science, Faculty of Food Science and Technology, 4Department of Veterinary Preclinical Sciences, Faculty of Veterinary Medicine, Universiti Putra Malaysia, Serdang, Selangor, Malaysia Abstract: Calcium carbonate aragonite polymorph nanoparticles derived from cockle shells were prepared using surface functionalization method followed by purification steps. Size, morphology, and surface properties of the nanoparticles were characterized using transmission electron microscopy, field emission scanning electron microscopy, dynamic light scattering, zetasizer, X-ray powder diffraction, and Fourier transform infrared spectrometry techniques. The potential of surface-functionalized calcium carbonate aragonite polymorph nanoparticle as a drug-delivery agent were assessed through in vitro drug-loading test and drug-release test. Transmission electron microscopy, field emission scanning electron microscopy, and particle size distribution analyses revealed that size, morphology, and surface characterization had been improved after surface functionalization process. Zeta potential of the nanoparticles was found to be increased, thereby demonstrating better dispersion among the nanoparticles. Purification techniques showed a further improvement in the overall distribution of nanoparticles toward more refined size ranges <100 nm, which specifically favored drug-delivery applications. The purity of the aragonite phase and their chemical analyses were verified by X-ray powder diffraction and Fourier transform infrared spectrometry studies. In vitro biological response of hFOB 1.19 osteoblast cells showed that surface functionalization could improve the cytotoxicity of cockle shell–based calcium carbonate aragonite nanocarrier. The sample was also sensitive to pH changes and

  12. Effect of BMI and body weight on pregnancy rates with LNG as emergency contraception: analysis of four WHO HRP studies.

    Science.gov (United States)

    Festin, Mario Philip R; Peregoudov, Alexandre; Seuc, Armando; Kiarie, James; Temmerman, Marleen

    2017-01-01

    To estimate the effect of increased body weight and body mass index (BMI) on pregnancy rates with levonorgestrel (LNG) 1.5mg used as emergency contraception (EC). The study reviewed data from 6873 women in four WHO-HRP randomized trials on EC conducted between 1993 and 2010. Participants took either 1.5mg of LNG as a single dose or in two doses 12h apart, up to 120h of unprotected intercourse. Contraceptive efficacy (pregnancy rates) at different weight and BMI categories was evaluated. Overall pregnancy rate was low at 1.2%. Pregnancy rates were also low in women weighing over 80kg (0.7%) and who were obese (BMI over 30kg/m 2 ) (2.0%). The pooled analyses for pregnancy demonstrated that BMI over 30kg/m 2 decreased efficacy significantly (odds ratio 8.27, 95% confidence interval = 2.70-25.37) when compared to women in lower BMI categories, mainly influenced by pregnancies in obese women from one study site. Sensitivity analyses excluding that site showed that obesity was no longer a risk factor; however, the other studies included too few obese women in the sample to exclude a substantial decrease in efficacy. Pregnancy rates with use of LNG 1.5mg for EC were low at less than 3% across different weight and BMI categories. Pooled analyses showed an increase in pregnancy rates among obese women (BMI more than 30kg/m 2 ) compared to women with normal BMI levels, influenced by pregnancies all coming from one study site. Access to LNG as EC should still be promoted to women who need them, and not be restricted in any weight or BMI category, with additional attention for counselling and advice for obese women. Copyright © 2016. Published by Elsevier Inc.

  13. Cell surface expression and function of the macromolecular C1 complex on the surface of human monocytes

    Directory of Open Access Journals (Sweden)

    Kinga K Hosszu

    2012-03-01

    Full Text Available The synthesis of the subunits of the C1 complex (C1q, C1s, C1r, and its regulator C1 inhibitor (C1-Inh by human monocytes has been previously established. However, surface expression of these molecules by monocytes has not been shown. Using flow cytometry and antigen-capture ELISA, we show here for the first time that, in addition to C1q, PB monocytes and the monocyte-derived U937 cells express C1s and C1r, as well as Factor B and C1-Inh on their surface. C1s and C1r immunoprecipitated with C1q, suggesting that at least some of the C1q on these cells is part of the C1 complex. Furthermore, the C1 complex on U937 cells was able to trigger complement activation via the classical pathway. The presence of C1-Inh may ensure that an unwarranted autoactivation of the C1 complex does not take place. Since C1-Inh closely monitors the activation of the C1 complex in a sterile or infectious inflammatory environment, further elucidation of the role of C1 complex is crucial to dissect its function in monocyte, DC and T cell activities, and its implications in host defense and tolerance.

  14. Nanodrop on a smooth solid surface with hidden roughness. Density functional theory considerations

    Science.gov (United States)

    Berim, Gersh O.; Ruckenstein, Eli

    2015-04-01

    A nanodrop of a test fluid placed on a smooth surface of a solid material of nonuniform density which covers a rough solid surface (hidden roughness) is examined, on the basis of the density functional theory (DFT), in the presence of an external perturbative force parallel to the surface. The contact angles which the drop profile makes with the surface at the leading edges of the drop are determined as functions of drop size and perturbative external force. A critical sticking force, defined as the largest value of the perturbative force for which the drop remains at equilibrium, is determined and its dependence on the size of the drop is explained on the basis of the shape of the interaction potential generated by the solid in vicinity of the leading edges of the drop. For even larger values of the perturbative force no drop-like solution of the Euler-Lagrange equation of the DFT was found. The upper bound of the inclination angle of a surface containing a macroscopic drop is estimated on the basis of results obtained for nanodrops and some experimental results are interpreted. The main conclusion is that the hidden roughness has a similar effect on the drop features as the traditionally considered physical and chemical roughnesses.

  15. In vitro characterization of two different atmospheric plasma jet chemical functionalizations of titanium surfaces

    Science.gov (United States)

    Mussano, F.; Genova, T.; Verga Falzacappa, E.; Scopece, P.; Munaron, L.; Rivolo, P.; Mandracci, P.; Benedetti, A.; Carossa, S.; Patelli, A.

    2017-07-01

    Plasma surface activation and plasma polymers deposition are promising technologies capable to modulate biologically relevant surface features of biomaterials. The purpose of this study was to evaluate the biological effects of two different surface modifications, i.e. amine (NH2-Ti) and carboxylic/esteric (COOH/R-Ti) functionalities obtained from 3-aminopropyltriethoxysilane (3-APTES) and methylmethacrylate (MMA) precursors, respectively, through an atmospheric plasma jet RF-APPJ portable equipment. The coatings were characterized by Scanning Electron Microscopy, FT-IR spectroscopy, XPS and surface energy calculations. Stability in water and after UV sterilization were also verified. The pre-osteoblastic murine cell line MC3T3-E1 was used to perform the in-vitro tests. The treated samples showed a higher quantity of adsorbed proteins and improved osteoblast cells adhesion on the surfaces compared to the pristine titanium, in particular the COOH/R-Ti led to a nearly two-fold improvement. Cell proliferation on coated samples was initially (at 24 h) lower than on titanium control, while, at 48 h, COOH/R-Ti reached the proliferation rate of pristine titanium. Cells grown on NH2-Ti were more tapered and elongated in shape with lower areas than on COOH/R-Ti enriched surfaces. Finally, NH2-Ti significantly enhanced osteocalcin production, starting from 14 days, while COOH/R-Ti had this effect only from 21 days. Notably, NH2-Ti was more efficient than COOH/R-Ti at 21 days. The amine functionality elicited the most relevant osteogenic effect in terms of osteocalcin expression, thus establishing an interesting correlation between early cell morphology and later differentiation stages. Taken together, these data encourage the use of the functionalization procedures here reported in further studies.

  16. Serum levels of vitamin A, visual function and ocular surface after bariatric surgery

    Directory of Open Access Journals (Sweden)

    Luana Paula Nogueira de Araújo BRANDÃO

    Full Text Available ABSTRACT BACKGROUND Bariatric surgery is the most effective treatment for severe obesity, but the surgery increases the risk of developing nutritional deficiencies, such as vitamin A deficiency. In human metabolism, vitamin A plays a role in vision. OBJECTIVE To evaluate serum vitamin A, visual function and ocular surface of patients undergoing bariatric surgery. METHODS A cross-sectional and analytical study was conduced with 28 patients undergoing bariatric surgery for at least 6 months. Ophthalmologic evaluation was done through color vision test, contrast sensitivity test, ocular surface tests and confocal microscopy, as well as vitamin A serum measurement. RESULTS Vertical sleeve gastrectomy was performed in seven (25.0% patients and Roux -en-Y gastric by-pass in 21 (75.0%. Mean serum vitamin A level was 1.7±0.5 µmoL/L. Most patients (60.7% had symptoms of dry eye. Five (17.9% patients had contrast sensitivity impairment and 18 (64.3% color vision changes. In the group of patients undergoing Roux -en-Y gastric by-pass , mean vitamin A levels were 1.8±0.6 µmoL/L, whereas they were 1.7±0.5 µmoL/L in patients submitted to the restrictive technique vertical sleeve gastrectomy . The analysis of the influence of serum levels of vitamin A in the visual function and ocular surface was performed by Pearson correlation test and there was no significant correlation between any of the variables and vitamin A. CONCLUSION There was no influence of the bariatric surgery technique used on serum vitamin A levels, on the visual function or on the ocular surface. Moreover, there was no correlation between serum levels of vitamin A and the visual function or the ocular surface changes.

  17. Serum levels of vitamin A, visual function and ocular surface after bariatric surgery.

    Science.gov (United States)

    Brandão, Luana Paula Nogueira de Araújo; Vilar, Lucio; Cavalcanti, Bernardo Menelau; Brandão, Pedro Henrique Amorim; Arantes, Tiago Eugênio Faria E; Campos, Josemberg Marins

    2017-01-01

    - Bariatric surgery is the most effective treatment for severe obesity, but the surgery increases the risk of developing nutritional deficiencies, such as vitamin A deficiency. In human metabolism, vitamin A plays a role in vision. - To evaluate serum vitamin A, visual function and ocular surface of patients undergoing bariatric surgery. - A cross-sectional and analytical study was conduced with 28 patients undergoing bariatric surgery for at least 6 months. Ophthalmologic evaluation was done through color vision test, contrast sensitivity test, ocular surface tests and confocal microscopy, as well as vitamin A serum measurement. - Vertical sleeve gastrectomy was performed in seven (25.0%) patients and Roux -en-Y gastric by-pass in 21 (75.0%). Mean serum vitamin A level was 1.7±0.5 µmoL/L. Most patients (60.7%) had symptoms of dry eye. Five (17.9%) patients had contrast sensitivity impairment and 18 (64.3%) color vision changes. In the group of patients undergoing Roux -en-Y gastric by-pass , mean vitamin A levels were 1.8±0.6 µmoL/L, whereas they were 1.7±0.5 µmoL/L in patients submitted to the restrictive technique vertical sleeve gastrectomy . The analysis of the influence of serum levels of vitamin A in the visual function and ocular surface was performed by Pearson correlation test and there was no significant correlation between any of the variables and vitamin A. - There was no influence of the bariatric surgery technique used on serum vitamin A levels, on the visual function or on the ocular surface. Moreover, there was no correlation between serum levels of vitamin A and the visual function or the ocular surface changes.

  18. Modification of Semiconductor Surfaces through Si-N Linkages by Wet-Chemistry Approaches and Modular Functionalization of Zinc Oxide Surfaces for Chemical Protection of Material Morphology

    Science.gov (United States)

    Gao, Fei

    Semiconductor substrates are widely used in many applications. Multiple practical uses involving these materials require the ability to tune their physical and chemical properties to adjust those to a specific application. In recent years, surface and interface reactions have affected dramatically device fabrication and material design. Novel surface functionalization techniques with diverse chemical approaches make the desired physical, thermal, electrical, and mechanical properties attainable. Meanwhile, the modified surface can serve as one of the most important key steps for further assembly process in order to make novel devices and materials. In the following chapters, novel chemical approaches to the functionalization of silicon and zinc oxide substrates will be reviewed and discussed. The specific functionalities including amines, azides, and alkynes on surfaces of different materials will be applied to address subsequent attachment of large molecules and assembly processes. This research is aimed to develop new strategies for manipulating the surface properties of semiconductor materials in a controlled way. The findings of these investigations will be relevant for future applications in molecular and nanoelectronics, sensing, and solar energy conversion. The ultimate goals of the projects are: 1) Preparation of an oxygen-and carbon-free silicon surface based exclusively on Si-N linkages for further modification protocols.. This project involves designing the surface reaction of hydrazine on chlorine-terminated silicon surface, introduction of additional functional group through dehydrohalogenation condensation reaction and direct covalent attachment of C60. 2) Demonstrating alternative method to anchor carbon nanotubes to solid substrates directly through the carbon cage.. This project targets surface modification of silicon and gold substrates with amine-terminated organic monolayers and the covalent attachment of nonfunctionalized and carboxylic acid-functionalized

  19. Bone-like apatite coating on functionalized poly(etheretherketone) surface via tailored silanization layers technique

    International Nuclear Information System (INIS)

    Zheng, Yanyan; Xiong, Chengdong; Zhang, Shenglan; Li, Xiaoyu; Zhang, Lifang

    2015-01-01

    Poly(etheretherketone) (PEEK) is a rigid semi-crystalline polymer with outstanding mechanical properties, bone-like stiffness and suitable biocompatibility that has attracted much interest as a biomaterial for orthopedic and dental implants. However, the bio-inert surface of PEEK limits its biomedical applications when direct osteointegration between the implants and the host tissue is desired. In this work, –PO 4 H 2 , –COOH and –OH groups were introduced on the PEEK surface by further chemical treatments of the vinyl-terminated silanization layers formed on the hydroxylation-pretreated PEEK surface. Both the surface-functionalized and pristine specimens were characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and water contact angle measurements. When placed in 1.5 strength simulated body fluid (SBF) solution, apatite was observed to form uniformly on the functionalized PEEK surface and firmly attach to the substrate. The characterized results demonstrated that the coating was constituted by poorly crystallized bone-like apatite and the effect of surface functional groups on coating formation was also discussed in detail. In addition, in vitro biocompatibility of PEEK, in terms of pre-osteoblast cell (MC3T3-E1) attachment, spreading and proliferation, was remarkably enhanced by the bone-like apatite coating. Thus, this study provides a method to enhance the bioactivity of PEEK and expand its applications in orthopedic and dental implants. - Highlights: • –PO 4 H 2 , –COOH and –OH groups were successfully introduced onto PEEK surface via tailored silanization layer technique. • Bone-like apatite formed uniformly on surface-functionalized PEEK after immersion in SBF, and tightly adhered to the PEEK. • SEM, EDS, FTIR, XPS and XRD results showed that apatite layer is composed of low-crystalline bone-like apatite. • Bone-like apatite coating remarkably enhanced pre

  20. Plastic Trash goes Biohybrid"-Rapid and Selective Functionalization of Inert Plastic Surfaces with Biomolecules

    DEFF Research Database (Denmark)

    Schiller, Stefan M; Kambhampati, Dev; Stengel, Gudrun

    2010-01-01

    The covalent functionalization of "inert" polymers such as polypropylene with biomolecules for biocompatible or biosensor surfaces is challenging. Here we present a powerful approach to covalently modify "inert" macromolecular surfaces with biomacromolecules reusing old plastic material. A special...... emphasis was placed on easily accessible materials and a process which is easy, fast, efficient, cheap, and reliable. "Plastic trash" (lids from Eppendorf® pipet tip containers) was used as a polymer substrate to demonstrate the use/reuse of commercial packing material to covalently modify this material...

  1. Bone-like apatite coating on functionalized poly(etheretherketone) surface via tailored silanization layers technique

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Yanyan [Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Xiong, Chengdong; Zhang, Shenglan [Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041 (China); Li, Xiaoyu [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Zhang, Lifang, E-mail: zhanglfcioc@163.com [Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041 (China)

    2015-10-01

    Poly(etheretherketone) (PEEK) is a rigid semi-crystalline polymer with outstanding mechanical properties, bone-like stiffness and suitable biocompatibility that has attracted much interest as a biomaterial for orthopedic and dental implants. However, the bio-inert surface of PEEK limits its biomedical applications when direct osteointegration between the implants and the host tissue is desired. In this work, –PO{sub 4}H{sub 2}, –COOH and –OH groups were introduced on the PEEK surface by further chemical treatments of the vinyl-terminated silanization layers formed on the hydroxylation-pretreated PEEK surface. Both the surface-functionalized and pristine specimens were characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and water contact angle measurements. When placed in 1.5 strength simulated body fluid (SBF) solution, apatite was observed to form uniformly on the functionalized PEEK surface and firmly attach to the substrate. The characterized results demonstrated that the coating was constituted by poorly crystallized bone-like apatite and the effect of surface functional groups on coating formation was also discussed in detail. In addition, in vitro biocompatibility of PEEK, in terms of pre-osteoblast cell (MC3T3-E1) attachment, spreading and proliferation, was remarkably enhanced by the bone-like apatite coating. Thus, this study provides a method to enhance the bioactivity of PEEK and expand its applications in orthopedic and dental implants. - Highlights: • –PO{sub 4}H{sub 2}, –COOH and –OH groups were successfully introduced onto PEEK surface via tailored silanization layer technique. • Bone-like apatite formed uniformly on surface-functionalized PEEK after immersion in SBF, and tightly adhered to the PEEK. • SEM, EDS, FTIR, XPS and XRD results showed that apatite layer is composed of low-crystalline bone-like apatite. • Bone-like apatite coating

  2. Gold nanoparticle surface functionalization: a necessary requirement in the development of novel nanotherapeutics.

    Science.gov (United States)

    Nicol, James R; Dixon, Dorian; Coulter, Jonathan A

    2015-01-01

    With several gold nanoparticle-based therapies currently undergoing clinical trials, these treatments may soon be in the clinic as novel anticancer agents. Gold nanoparticles are the subject of a wide ranging international research effort with preclinical studies underway for multiple applications including photoablation, diagnostic imaging, radiosensitization and multifunctional drug-delivery vehicles. These applications require an increasingly complex level of surface modification in order to achieve efficacy and limit off-target toxicity. This review will discuss the main obstacles in relation to surface functionalization and the chemical approaches commonly utilized. Finally, we review a range of recent preclinical studies that aim to advance gold nanoparticle treatments toward the clinic.

  3. Adhesion of oxide layer to metal-doped aluminum hydride surface: Density functional calculations

    Science.gov (United States)

    Takezawa, Tomoki; Itoi, Junichi; Kannan, Takashi

    2017-07-01

    The density functional theory (DFT) calculations were carried out to evaluate the adhesion energy of the oxide layer to the metal-doped surface of hydrogen storage material, aluminum hydride (alane, AlH3). The total energy calculations using slab model revealed that the surface doping of some metals to aluminum hydride weakens the adhesion strength of the oxide layer. The influence of titanium, iron, cobalt, and zirconium doping on adhesion strength were evaluated. Except for iron doping, the adhesion strength becomes weak by the doping.

  4. Analysis of the phonon surface specific heat using Green function techniques

    International Nuclear Information System (INIS)

    Silva Carrico, A. da; Albuquerque, E.L. de

    1981-01-01

    Green functions are derived for the displacement associated with acoustic vibrations in isotropic elastic media and used to evaluate the surface specific heat in the harmonic approximation. Only the low-temperature limit case is considered since, provided K sub(B) T/h is very small, the dispersion relation for the three acoustic branches can be replaced by its long-wavelenght form. The contributions of surface elastic waves of the Rayleigh and Love types are pointed out and their features discussed. The nature of the result and their relations to previous work in this field is also presented and discussed. (Author) [pt

  5. Analysis of the phonon surface specific heat using Green function techniques

    International Nuclear Information System (INIS)

    Carrico, A.S.; Albuquerque, E.L.

    1980-01-01

    Green functions are derived for the displacement associated with acoustic vibrations in isotropic elastic media and used to evaluate the surface specific heat in the harmonic approximation. We consider only the low-temperature limit case since, provided K B 1/h is very samll, we can replace the dispersion relation for the three acoustic branches by its long-wavelenghts form. The contributions of surface elastic waves ot the Rayleigh and Love types are pointed out and their features discussed. The nature of the result and their relations to previous work in this field is also presented and discussed. (author) [pt

  6. The visibility of galaxies as a function of central surface brightness

    International Nuclear Information System (INIS)

    Disney, M.; Phillipps, S.

    1983-01-01

    The likelihood of a galaxy with given intrinsic profile appearing in a photograph catalogue with limiting criteria on apparent magnitude and angular size will depend on the maximum distance at which such a galaxy can lie and still obey both criteria. It is demonstrated that the corresponding volume in which the galaxy will be visible is a sensitive function of the galaxy's central surface brightness as well as its absolute magnitude. Before the observed concentrations around preferred values of surface brightness can be regarded as real, it will be necessary to make allowance for this selection effect. (author)

  7. Green's function surface-integral method for nonlocal response of plasmonic nanowires in arbitrary dielectric environments

    DEFF Research Database (Denmark)

    Yan, Wei; Mortensen, N. Asger; Wubs, Martijn

    2013-01-01

    We develop a nonlocal-response generalization to the Green's function surface-integral method (GSIM), also known as the boundary-element method. This numerically efficient method can accurately describe the linear hydrodynamic nonlocal response of arbitrarily shaped plasmonic nanowires in arbitrary...... and the longitudinal wave number become smaller, or when the effective background permittivity or the mode inhomogeneity increase. The inhomogeneity can be expressed in terms of an effective angular momentum of the surface-plasmon mode. We compare local and nonlocal response of freestanding nanowires, and of nanowires...

  8. Surface functionalization of epitaxial graphene on SiC by ion irradiation for gas sensing application

    Science.gov (United States)

    Kaushik, Priya Darshni; Ivanov, Ivan G.; Lin, Pin-Cheng; Kaur, Gurpreet; Eriksson, Jens; Lakshmi, G. B. V. S.; Avasthi, D. K.; Gupta, Vinay; Aziz, Anver; Siddiqui, Azher M.; Syväjärvi, Mikael; Yazdi, G. Reza

    2017-05-01

    In this work, surface functionalization of epitaxial graphene grown on silicon carbide was performed by ion irradiation to investigate their gas sensing capabilities. Swift heavy ion irradiation using 100 MeV silver ions at four varying fluences was implemented on epitaxial graphene to investigate morphological and structural changes and their effects on the gas sensing capabilities of graphene. Sensing devices are expected as one of the first electronic applications using graphene and most of them use functionalized surfaces to tailor a certain function. In our case, we have studied irradiation as a tool to achieve functionalization. Morphological and structural changes on epitaxial graphene layers were investigated by atomic force microscopy, Raman spectroscopy, Raman mapping and reflectance mapping. The surface morphology of irradiated graphene layers showed graphene folding, hillocks, and formation of wrinkles at highest fluence (2 × 1013 ions/cm2). Raman spectra analysis shows that the graphene defect density is increased with increasing fluence, while Raman mapping and reflectance mapping show that there is also a reduction of monolayer graphene coverage. The samples were investigated for ammonia and nitrogen dioxide gas sensing applications. Sensors fabricated on pristine and irradiated samples showed highest gas sensing response at an optimal fluence. Our work provides new pathways for introducing defects in controlled manner in epitaxial graphene, which can be used not only for gas sensing application but also for other applications, such as electrochemical, biosensing, magnetosensing and spintronic applications.

  9. Influence of surface functionalization on the hydrophilic character of mesoporous silica nanoparticles.

    Science.gov (United States)

    Musso, G E; Bottinelli, E; Celi, L; Magnacca, G; Berlier, G

    2015-06-07

    We report the synthesis and surface functionalization of MCM-41-like mesoporous silica nanoparticles (MSNs) with spheroidal shape and particle size of 141 ± 41 nm. The success of surface functionalization with aminopropyl and sodium ethylcarboxylate groups (giving amino-MSN and carboxy-MSN, respectively) was ascertained by infrared spectroscopy and ζ potential measurements. The former showed the decrease of surface silanol groups and the corresponding appearance of signals related to NH2 bending mode (δNH2) at 1595 cm(-1) and COO(-) stretching (νas and νsym) at 1562 and 1418 cm(-1). The latter showed a change in surface charge, in that the isoelectric point (IEP) changed from pH 3-4.5 to 8.5 when the MSN was functionalized with the amino groups, while carboxy-MSN showed a more negative charge in the whole pH range with respect to MSN. The hydrophilic character of the prepared materials was ascertained by quantitative microgravimetric measurements, allowing the calculation of the average isosteric adsorption heat (q[combining macron]st). This was found to be 51 ± 3 kJ mol(-1), 61 ± 4, and 65 ± 3 kJ mol(-1) for MSN, amino-MSN, and carboxy-MSN samples, respectively. The increase in q[combining macron]st after functionalization can be ascribed to the specific interaction of water molecules with the functionalizing agents, in agreement with a higher basicity with respect to silanol groups. Moreover, the possibility of multiple H-bonding interactions of water molecules with the carboxylate anion is put forward to account for the higher water uptake with respect to parent MSN.

  10. Renal function maturation in children: is normalization to surface area valid?

    International Nuclear Information System (INIS)

    Rutland, M.D.; Hassan, I.M.; Que, L.

    1999-01-01

    Full text: Gamma camera DTPA renograms were analysed to measure renal function by the rate at which the kidneys took up tracer from the blood. This was expressed either directly as the fractional uptake rate (FUR), which is not related to body size, or it was converted to a camera-based GFR by the formula GFR blood volume x FUR, and this GFR was normalized to a body surface area of 1.73 m2. Most of the patients studied had one completely normal kidney, and one kidney with reflux but normal function and no large scars. The completely normal kidneys contributed, on average, 50% of the total renal function. The results were considered in age bands, to display the effect of age on renal function. The camera-GFR measurements showed the conventional results of poor renal function in early childhood, with a slow rise to near-adult values by the age of 2 years, and somewhat low values throughout childhood. The uptake values showed a different pattern, with renal function rising to adult equivalent values by the age of 4 months, and with children having better renal function than adults throughout most of their childhood. The standard deviations expressed as coefficients of variation (CV) were smaller for the FUR technique than the GFR (Wilcoxon rank test, P < 0.01). These results resemble recent published measurements of absolute DMSA uptake, which are also unrelated to body size and show early renal maturation. The results also suggest that the reason children have lower serum creatinine levels than adults is that they have better renal function. If this were confirmed, it would raise doubts about the usefulness of normalizing renal function to body surface area in children

  11. Hydrogen atom addition to the surface of graphene nanoflakes: A density functional theory study

    International Nuclear Information System (INIS)

    Tachikawa, Hiroto

    2017-01-01

    Highlights: • The reaction pathway of the hydrogen addition to graphene surface was determined by the DFT method. • Binding energies of atomic hydrogen to graphene surface were determined. • Absorption spectrum of hydrogenated graphene was theoretically predicted. • Hyperfine coupling constant of hydrogenated graphene was theoretically predicted. - Abstract: Polycyclic aromatic hydrocarbons (PAHs) provide a 2-dimensional (2D) reaction surface in 3-dimensional (3D) interstellar space and have been utilized as a model of graphene surfaces. In the present study, the reaction of PAHs with atomic hydrogen was investigated by means of density functional theory (DFT) to systematically elucidate the binding nature of atomic hydrogen to graphene nanoflakes. PAHs with n = 4–37 were chosen, where n indicates the number of benzene rings. Activation energies of hydrogen addition to the graphene surface were calculated to be 5.2–7.0 kcal/mol at the CAM-B3LYP/6-311G(d,p) level, which is almost constant for all PAHs. The binding energies of hydrogen atom were slightly dependent on the size (n): 14.8–28.5 kcal/mol. The absorption spectra showed that a long tail is generated at the low-energy region after hydrogen addition to the graphene surface. The electronic states of hydrogenated graphenes were discussed on the basis of theoretical results.

  12. Hydrogen atom addition to the surface of graphene nanoflakes: A density functional theory study

    Energy Technology Data Exchange (ETDEWEB)

    Tachikawa, Hiroto, E-mail: hiroto@eng.hokudai.ac.jp

    2017-02-28

    Highlights: • The reaction pathway of the hydrogen addition to graphene surface was determined by the DFT method. • Binding energies of atomic hydrogen to graphene surface were determined. • Absorption spectrum of hydrogenated graphene was theoretically predicted. • Hyperfine coupling constant of hydrogenated graphene was theoretically predicted. - Abstract: Polycyclic aromatic hydrocarbons (PAHs) provide a 2-dimensional (2D) reaction surface in 3-dimensional (3D) interstellar space and have been utilized as a model of graphene surfaces. In the present study, the reaction of PAHs with atomic hydrogen was investigated by means of density functional theory (DFT) to systematically elucidate the binding nature of atomic hydrogen to graphene nanoflakes. PAHs with n = 4–37 were chosen, where n indicates the number of benzene rings. Activation energies of hydrogen addition to the graphene surface were calculated to be 5.2–7.0 kcal/mol at the CAM-B3LYP/6-311G(d,p) level, which is almost constant for all PAHs. The binding energies of hydrogen atom were slightly dependent on the size (n): 14.8–28.5 kcal/mol. The absorption spectra showed that a long tail is generated at the low-energy region after hydrogen addition to the graphene surface. The electronic states of hydrogenated graphenes were discussed on the basis of theoretical results.

  13. Investigation on large-area fabrication of vivid shark skin with superior surface functions

    Science.gov (United States)

    Chen, Huawei; Zhang, Xin; Ma, Lingxi; Che, Da; Zhang, Deyuan; Sudarshan, T. S.

    2014-10-01

    Shark skin has attracted worldwide attention because of its superior drag reduction, antifouling performance induced from its unique surface morphology. Although the vivid shark skin has been fabricated by a bio-replicated micro-imprinting approach in previous studies and superior drag reduction effect has been validated in water tunnel, continuous large-area fabrication is still an obstacle to wide apply. In this paper, one novel bio-replication coating technology is proposed for large-area transfer of shark skin based on rapid UV curable paint. Apart from design of coating system, bio-replication accuracy of surface morphology was validated about 97% by comparison between shark skin template and coating surface morphology. Finally, the drag reduction and anti-fouling function of coating surface were tested in water tunnel and open algae pond respectively. Drag reduction rate of coating surface was validated about 12% higher and anti-fouling was proved to about hundred times ameliorate, all of which are more excellent than simple 2D riblet surface.

  14. Functionalization of polymer surfaces by medium frequency non-thermal plasma

    Science.gov (United States)

    Felix, T.; Trigueiro, J. S.; Bundaleski, N.; Teodoro, O. M. N. D.; Sério, S.; Debacher, N. A.

    2018-01-01

    This work addresses the surface modification of different polymers by argon dielectric barrier discharge, using bromoform vapours. Atomic Force Microscopy and Scanning Electron Microscopy showed that plasma etching occurs in stages and may be related to the reach of the species generated and obviously the gap between the electrodes. In addition, the stages of flatten surface or homogeneity may be the result of the transient crosslinking promoted by the intense UV radiation generated by the non- thermal plasma. X-ray Photoelectron Spectroscopy analysis showed that bromine was inserted on the polymer surface as Csbnd Br bonds and as adsorbed HBr. The obtained results demonstrate that the highest degree of bromofunctionalization was achieved on polypropylene surface, which contains about 8,5% of Br. After its derivatization in ammonia, Br disappeared and about 6% of nitrogen in the form of amine group was incorporated at the surface. This result can be considered as a clear fingerprint of the Br substitution by the amine group, thus illustrating the efficiency of the proposed method for functionalization of polymer surfaces.

  15. Near Surface Stoichiometry in UO2: A Density Functional Theory Study

    Directory of Open Access Journals (Sweden)

    Jianguo Yu

    2015-01-01

    Full Text Available The mechanisms of oxygen stoichiometry variation in UO2 at different temperature and oxygen partial pressure are important for understanding the dynamics of microstructure in these crystals. However, very limited experimental studies have been performed to understand the atomic structure of UO2 near surface and defect effects of near surface on stoichiometry in which the system can exchange atoms with the external reservoir. In this study, the near (110 surface relaxation and stoichiometry in UO2 have been studied with density functional theory (DFT calculations. On the basis of the point-defect model (PDM, a general expression for the near surface stoichiometric variation is derived by using DFT total-energy calculations and atomistic thermodynamics, in an attempt to pin down the mechanisms of oxygen exchange between the gas environment and defected UO2. By using the derived expression, it is observed that, under poor oxygen conditions, the stoichiometry of near surface is switched from hyperstoichiometric at 300 K with a depth around 3 nm to near-stoichiometric at 1000 K and hypostoichiometric at 2000 K. Furthermore, at very poor oxygen concentrations and high temperatures, our results also suggest that the bulk of the UO2 prefers to be hypostoichiometric, although the surface is near-stoichiometric.

  16. Density functional theory formulation for fluid adsorption on correlated random surfaces

    Science.gov (United States)

    Aslyamov, Timur; Khlyupin, Aleksey

    2017-10-01

    We provide novel random surface density functional theory (RSDFT) formulation in the case of geometric heterogeneous surfaces of solid media which is essential for the description of thermodynamic properties of confined fluids. The major difference of our theoretical approach from the existing ones is a stochastic model of solid surfaces which takes into account the correlation properties of geometry. The main building blocks are effective fluid-solid potentials developed in the work of Khlyupin and Aslyamov [J. Stat. Phys. 167, 1519 (2017)] and geometry-based modification of the Helmholtz free energy for Lennard-Jones fluids. The efficiency of RSDFT is demonstrated in the calculation of argon and nitrogen low temperature adsorption on real heterogeneous surfaces (BP280 carbon black). These results are in good agreement with experimental data published in the literature. Also several models of corrugated materials are developed in the framework of RSDFT. Numerical analysis demonstrates a strong influence of surface roughness characteristics on adsorption isotherms. Thus the developed formalism provides a connection between a rigorous description of the stochastic surface and confined fluid thermodynamics.

  17. Catalytic water dissociation by greigite Fe3S4 surfaces: density functional theory study

    Science.gov (United States)

    Roldan, A.; de Leeuw, N. H.

    2016-01-01

    The iron sulfide mineral greigite, Fe3S4, has shown promising capability as a hydrogenating catalyst, in particular in the reduction of carbon dioxide to produce small organic molecules under mild conditions. We employed density functional theory calculations to investigate the {001},{011} and {111} surfaces of this iron thiospinel material, as well as the production of hydrogen ad-atoms from the dissociation of water molecules on the surfaces. We systematically analysed the adsorption geometries and the electronic structure of both bare and hydroxylated surfaces. The sulfide surfaces presented a higher flexibility than the isomorphic oxide magnetite, Fe3O4, allowing perpendicular movement of the cations above or below the top atomic sulfur layer. We considered both molecular and dissociative water adsorption processes, and have shown that molecular adsorption is the predominant state on these surfaces from both a thermodynamic and kinetic point of view. We considered a second molecule of water which stabilizes the system mainly by H-bonds, although the dissociation process remains thermodynamically unfavourable. We noted, however, synergistic adsorption effects on the Fe3S4{001} owing to the presence of hydroxyl groups. We concluded that, in contrast to Fe3O4, molecular adsorption of water is clearly preferred on greigite surfaces. PMID:27274698

  18. Surface functional group characterization using chemical derivatization X-ray photoelectron spectroscopy (CD-XPS)

    Energy Technology Data Exchange (ETDEWEB)

    Jagst, Eda

    2011-03-18

    Chemical derivatization - X-ray photolectron spectroscopy (CD-XPS) was applied successfully in order to determine different functional groups on thin film surfaces. Different amino group carrying surfaces, prepared by spin coating, self-assembly and plasma polymerization, were successfully investigated by (XPS) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. Amino groups were derivatized with the widely used primary amino group tags, pentafluorobenzaldehyde (PFB) and 4-(trifluoromethyl)-benzaldehyde (TFBA), prior to analysis. Primary amino group quantification was then carried out according to the spectroscopical data. Self-assembled monolayers (SAMs) of different terminal groups were prepared and investigated with XPS and spectra were compared with reference surfaces. An angle resolved NEXAFS measurement was applied to determine the orientation of SAMs. Plasma polymerized allylamine samples with different duty cycle, power and pressure values were prepared in order to study the effects of external plasma parameters on the primary amino group retention. CD-XPS was used to quantify the amino groups and experiments show, that the milder plasma conditions promote the retention of amino groups originating from the allylamine monomer. An interlaboratory comparison of OH group determination on plasma surfaces of polypropylene treated with oxygen plasma, was studied. The surfaces were investigated with XPS and the [OH] amount on the surfaces was calculated. (orig.)

  19. Origin of synergistic effect over Ni-based bimetallic surfaces: A density functional theory study

    Science.gov (United States)

    Fan, Chen; Zhu, Yi-An; Xu, Yue; Zhou, Yan; Zhou, Xing-Gui; Chen, De

    2012-07-01

    Density functional theory calculations have been conducted to explore the physical origin of the synergistic effect over Ni-based surface alloys using methane dissociation as a probe reaction. Some late transition metal atoms (M = Cu, Ru, Rh, Pd, Ag, Pt, and Au) are substituted for surface Ni atoms to examine the variation in electronic structure and adsorption property of Ni(111). Two types of threefold hollow sites, namely, the Ni2M and Ni3 sites, are taken into account. The calculated results indicate that the variation in the CHx adsorption energy at the Ni2M and Ni3 sites is dominated by the ensemble and ligand effect, respectively, and the other factors such as surface and adsorbate distortion and electrostatic interaction affect the catalytic properties of the bimetallic surfaces to a smaller extent. Both the Brønsted-Evans-Polanyi relationship and the scaling correlation hold true on the Ni-based bimetallic surfaces. With the combination of these two linear energy relations, the corrected binding energy of atomic C is found to be a good descriptor for representing the catalytic activity of the alloyed surfaces. Considering the compromise between the catalytic activity and catalyst stability, we suggest that the Rh/Ni catalyst is a good candidate for methane dissociation.

  20. Bio-functionalization of electro-synthesized polypyrrole surface by heme enzyme using a mixture of Nafion and glutaraldehyde as synergetic immobilization matrix: Conformational characterization and electrocatalytic studies

    Energy Technology Data Exchange (ETDEWEB)

    ElKaoutit, Mohammed, E-mail: elkaoutit@uca.es [Departamento de Quimica Analitica, Facultad de Ciencias, Universidad de Cadiz, 11510 Puerto Real, Cadiz (Spain); Naranjo-Rodriguez, Ignacio [Departamento de Quimica Analitica, Facultad de Ciencias, Universidad de Cadiz, 11510 Puerto Real, Cadiz (Spain); Dominguez, Manuel [Departamento de Fisica de la Materia Condensada, Facultad de Ciencias, Universidad de Cadiz, 11510 Puerto Real, Cadiz (Spain); Hidalgo-Hidalgo-de-Cisneros, Jose Luis [Departamento de Quimica Analitica, Facultad de Ciencias, Universidad de Cadiz, 11510 Puerto Real, Cadiz (Spain)

    2011-10-01

    Use of a mixture of Nafion and glutaraldehyde as new immobilization matrix was described. The percentage of Nafion was optimized to prevent denaturation of horseradish peroxidase enzyme after its crosslinkage with glutaraldehyde on electro-synthesized polypyrrole surface. Topographic study by Atomic Force Microscopy (AFM) shows that the enzyme seems to have been introduced inside the ionic cluster of Nafion. The characterization of the resulting bio-interfaces by UV-vis and FT-IR shows that the intra-crosslinkage phenomena caused by the use of glutaraldehyde can be eliminated by the optimization of the concentration of Nafion additive. The secondary structure contents of native and immobilized enzyme were analyzed by a Gaussian curve fitting of the respective FT-IR spectra in the amide I region. Immobilized enzyme presented notable increasing percentages of globular and short helical structure compared with native enzyme. This indicates that immobilized enzyme was folded which is in accordance with AFM studies and supports the enzyme entrance inside ionic clutter of Nafion. Thanks to synergic effects of the polypyrrole conducting polymer and the perfluorosulfonic acid polymer Nafion, HRP enzyme was immobilized in its 'native' state, the resulting biosensor was able to sense peroxide without any chemical mediator and can be categorized as third generation.

  1. Bio-functionalization of electro-synthesized polypyrrole surface by heme enzyme using a mixture of Nafion and glutaraldehyde as synergetic immobilization matrix: Conformational characterization and electrocatalytic studies

    International Nuclear Information System (INIS)

    ElKaoutit, Mohammed; Naranjo-Rodriguez, Ignacio; Dominguez, Manuel; Hidalgo-Hidalgo-de-Cisneros, Jose Luis

    2011-01-01

    Use of a mixture of Nafion and glutaraldehyde as new immobilization matrix was described. The percentage of Nafion was optimized to prevent denaturation of horseradish peroxidase enzyme after its crosslinkage with glutaraldehyde on electro-synthesized polypyrrole surface. Topographic study by Atomic Force Microscopy (AFM) shows that the enzyme seems to have been introduced inside the ionic cluster of Nafion. The characterization of the resulting bio-interfaces by UV-vis and FT-IR shows that the intra-crosslinkage phenomena caused by the use of glutaraldehyde can be eliminated by the optimization of the concentration of Nafion additive. The secondary structure contents of native and immobilized enzyme were analyzed by a Gaussian curve fitting of the respective FT-IR spectra in the amide I region. Immobilized enzyme presented notable increasing percentages of globular and short helical structure compared with native enzyme. This indicates that immobilized enzyme was folded which is in accordance with AFM studies and supports the enzyme entrance inside ionic clutter of Nafion. Thanks to synergic effects of the polypyrrole conducting polymer and the perfluorosulfonic acid polymer Nafion, HRP enzyme was immobilized in its 'native' state, the resulting biosensor was able to sense peroxide without any chemical mediator and can be categorized as third generation.

  2. Synthesis and electronic properties of chemically functionalized graphene on metal surfaces

    International Nuclear Information System (INIS)

    Grüneis, Alexander

    2013-01-01

    A review on the electronic properties, growth and functionalization of graphene on metals is presented. Starting from the derivation of the electronic properties of an isolated graphene layer using the nearest neighbor tight-binding (TB) approximation for π and σ electrons, the TB model is then extended to third-nearest neighbors and interlayer coupling. The latter is relevant to few-layer graphene and graphite. Next, the conditions under which epitaxial graphene can be obtained by chemical vapor deposition are reviewed with a particular emphasis on the Ni(111) surface. Regarding functionalization, I first discuss the intercalation of monolayer Au into the graphene/Ni(111) interface, which renders graphene quasi-free-standing. The Au intercalated quasi-free-standing graphene is then the basis for chemical functionalization. Functionalization of graphene is classified into covalent, ionic and substitutional functionalization. As archetypical examples for these three possibilities I discuss covalent functionalization by hydrogen, ionic functionalization by alkali metals and substitutional functionalization by nitrogen heteroatoms.

  3. Methyl Butanoate Adsorption on MoS2 Surface: A Density Functional Theory Investigation

    Directory of Open Access Journals (Sweden)

    Prabowo Wahyu Aji Eko

    2018-01-01

    Full Text Available Methyl butanoate is one of the compound which is obtained from triglyceride molecule. It has hydrocarbon components and hence may produce hydrocarbon through hydrodeoxygenation (HDO or decarbonylation (DCO processes. The first step to uncover the underlying mechanism of HDO or DCO is to find the active site of methyl butanoate adsorption over the catalyst. This study attempts to investigate the active site of methyl butanoate adsorption on MoS2 surface. Stable bonding configuration for methyl butanoate adsorption on MoS2 is investigated by using density functional theory (DFT. This investigation consists of geometry optimisation and adsorption energy calculations. The stable configuration of methyl butanoate adsorption on MoS2 surface is found to be on top of Mo atom in Mo-edge surface.

  4. Finite Element Analysis of Surface Residual Stress in Functionally Gradient Cemented Carbide Tool

    Science.gov (United States)

    Su, Chuangnan; Liu, Deshun; Tang, Siwen; Li, Pengnan; Qiu, Xinyi

    2018-03-01

    A component distribution model is proposed for three-component functionally gradient cemented carbide (FGCC) based on electron probe microanalysis results obtained for gradient layer thickness, microstructure, and elemental distribution. The residual surface stress of FGCC-T5 tools occurring during the fabrication process is analyzed using an ANSYS-implemented finite element method (FEM) and X-ray diffraction. A comparison of the experimental and calculated values verifies the feasibility of using FEM to analyze the residual surface stress in FGCC-T5 tools. The effects of the distribution index, geometrical shape, substrate thickness, gradient layer thickness, and position of the cobalt-rich layer on residual surface stress are studied in detail.

  5. Metrological Aspects of Surface Topographies Produced by Different Machining Operations Regarding Their Potential Functionality

    Directory of Open Access Journals (Sweden)

    Żak Krzysztof

    2017-06-01

    Full Text Available This paper presents a comprehensive methodology for measuring and characterizing the surface topographies on machined steel parts produced by precision machining operations. The performed case studies concern a wide spectrum of topographic features of surfaces with different geometrical structures but the same values of the arithmetic mean height Sa. The tested machining operations included hard turning operations performed with CBN tools, grinding operations with Al2O3 ceramic and CBN wheels and superfinish using ceramic stones. As a result, several characteristic surface textures with the Sa roughness parameter value of about 0.2 μm were thoroughly characterized and compared regarding their potential functional capabilities. Apart from the standard 2D and 3D roughness parameters, the fractal, motif and frequency parameters were taken in the consideration.

  6. Surface Functionalization of Piezoelectric Aluminum Nitride with Selected Amino Acid and Peptides

    Science.gov (United States)

    Chan, Edmund Ho Man

    In the present contribution, we elaborate on the covalent attachment of the amino acid cysteine and selected cysteine-bearing peptides, in aqueous buffered media, onto AlN surfaces modified with adlayers of one of our homemade bifunctional alkyltrichlorosilane cross-linking molecules bearing the benzenethiosulfonate head group. Surface characterizations confirmed the successful covalent immobilization of cysteine in buffered media, whereas the attachment of the peptides proved to be difficult as the undesired partial destruction of the adlayer on AlN by hydrolysis in aqueous/buffered solvent systems, which was confirmed in a separate study, appeared to have interfered with the covalent attachment and resulted in one of the peptides failing to immobilize. Future directions from this will focus on optimizing the solvent conditions for the cysteine/peptide immobilizations and the implementation of the surface chemistry to the covalent functionalization of AlN with biologically significant protein fragments, among them the antigen-binding fragment of antibodies.

  7. Preparation of self-cleaning surfaces with a dual functionality of superhydrophobicity and photocatalytic activity

    Science.gov (United States)

    Park, Eun Ji; Yoon, Hye Soo; Kim, Dae Han; Kim, Yong Ho; Kim, Young Dok

    2014-11-01

    Thin film of polydimethylsiloxane (PDMS) was deposited on SiO2 nanoparticles by chemical vapor deposition, and SiO2 became completely hydrophobic after PDMS coating. Mixtures of TiO2 and PDMS-coated SiO2 nanoparticles with various relative ratios were prepared, and distributed on glass surfaces, and water contact angles and photocatalytic activities of these surfaces were studied. Samples consisting of TiO2 and PDMS-coated SiO2 with a ratio of 7:3 showed a highly stable superhydrophobicity under UV irradiation with a water contact angle of 165° and UV-driven photocatalytic activity for decomposition of methylene blue and phenol in aqueous solution. Our process can be exploited for fabricating self-cleaning surfaces with dual functionality of superhydrophobicity and photocatalytic activity at the same time.

  8. Improving surface functional properties of tofu whey-derived peptides by chemical modification with fatty acids.

    Science.gov (United States)

    Matemu, Athanasia Oswald; Katayama, Shigeru; Kayahara, Hisataka; Murasawa, Hisashi; Nakamura, Soichiro

    2012-04-01

    Effect of acylation with saturated fatty acids on surface functional properties of tofu whey-derived peptides was investigated. Tofu whey (TW) and soy proteins (7S, 11S, and acid-precipitated soy protein [APP]) were hydrolyzed by Protease M 'Amano' G, and resulting peptide mixtures were acylated with esterified fatty acids of different chain length (6C to 18C) to form a covalent linkage between the carboxyl group of fatty acid and the free amino groups of peptide. Acylation significantly (P properties of 7S, 11S, and APP peptides independent of fatty acid chain length. Acylation decreased water binding capacity although oil binding capacity of acylated tofu whey ultra filtered fraction (UFTW acids had shown significant higher surface hydrophobicity as in contrast with acylated UFTW acids can further affect functional properties of soy proteins. © 2012 Institute of Food Technologists®

  9. Tailor-Made Pore Surface Engineering in Covalent Organic Frameworks: Systematic Functionalization for Performance Screening.

    Science.gov (United States)

    Huang, Ning; Krishna, Rajamani; Jiang, Donglin

    2015-06-10

    Imine-linked covalent organic frameworks (COFs) were synthesized to bear content-tunable, accessible, and reactive ethynyl groups on the walls of one-dimensional pores. These COFs offer an ideal platform for pore-wall surface engineering aimed at anchoring diverse functional groups ranging from hydrophobic to hydrophilic units and from basic to acidic moieties with controllable loading contents. This approach enables the development of various tailor-made COFs with systematically tuned porosities and functionalities while retaining the crystallinity. We demonstrate that this strategy can be used to efficiently screen for suitable pore structures for use as CO2 adsorbents. The pore-surface-engineered walls exhibit an enhanced affinity for CO2, resulting in COFs that can capture and separate CO2 with high performance.

  10. Syndecans as cell surface receptors: Unique structure equates with functional diversity

    DEFF Research Database (Denmark)

    Choi, Youngsil; Chung, Heesung; Jung, Heyjung

    2011-01-01

    An increasing number of functions for syndecan cell surface heparan sulfate proteoglycans have been proposed over the last decade. Moreover, aberrant syndecan regulation has been found to play a critical role in multiple pathologies, including cancers, as well as wound healing and inflammation....... As receptors, they have much in common with other molecules on the cell surface. Syndecans are type I transmembrane molecules with cytoplasmic domains that link to the actin cytoskeleton and can interact with a number of regulators. However, they are also highly complex by virtue of their external...... glycosaminoglycan chains, especially heparan sulfate. This heterodisperse polysaccharide has the potential to interact with many ligands from diverse protein families. Here, we relate the structural features of syndecans to some of their known functions....

  11. The oriented and patterned growth of fluorescent metal–organic frameworks onto functionalized surfaces

    Directory of Open Access Journals (Sweden)

    Jinliang Zhuang

    2012-08-01

    Full Text Available A metal–organic framework (MOF material, [Zn2(adc2(dabco] (adc = anthracene-9,10-dicarboxylate, dabco = 1,4-diazabicyclo[2.2.2]­octane, the fluorescence of which depends on the loading of its nanopores, was synthesized in two forms: as free-flowing nanocrystals with different shapes and as surface-attached MOFs (SURMOFs. For the latter, we used self-assembled monolayers (SAMs bearing functional groups, such as carboxylate and pyridyl groups, capable of coordinating to the constituents of the MOF. It could be demonstrated that this directed coordination also orients the nanocrystals deposited at the surface. Using two different patterning methods, i.e., microcontact printing and electron-beam lithography, the lateral distribution of the functional groups could be determined in such a way that the highly localized deposition of the SURMOF films became possible.

  12. Surface functionalization dependent subcellular localization of Superparamagnetic nanoparticle in plasma membrane and endosome.

    Science.gov (United States)

    Thimiri Govinda Raj, Deepak B; Khan, Niamat Ali

    2018-01-01

    In this article, we elaborate the application of thermal decomposition based synthesis of Fe 3 O 4 superparamagnetic nanoparticle (SPMNP) in subcellular fractionation context. Here, we performed surface functionalization of SPMNP with phospholipids and dimercaptosuccinic acid. Surprisingly, we observed surface functionalization dependent SPMNP localization in subcellular compartments such as plasma membrane, endosomes and lysosomes. By using SPMNP based subcellular localization with pulse-chase methodology, we could use SPMNP for high pure-high yield organelle (plasma membrane, endosomes and lysosome) fractionation. Further, SPMNP that are distinctly localized in subcellular compartments can be used as technology for subcellular fractionation that can complement existing tools for cell biology research. As a future perspective, isolated magnetic organelles can be extended to protein/protein complex purification for biochemical and structural biology studies.

  13. Functional mapping of cell surface proteins with localized stimulation of single cells

    Science.gov (United States)

    Sun, Bingyun; Chiu, Daniel T.

    2003-11-01

    This paper describes the development of using individual micro and nano meter-sized vesicles as delivery vessels to functionally map the distribution of cell surface proteins at the level of single cells. The formation of different sizes of vesicles from tens of nanometers to a few micrometers in diameter that contain the desired molecules is addressed. An optical trap is used to manipulate the loaded vesicle to specific cell morphology of interest, and a pulsed UV laser is used to photo-release the stimuli onto the cell membrane. Carbachol activated cellular calcium flux, upon binding to muscarinic acetylcholine receptors, is studied by this method, and the potential of using this method for the functional mapping of localized proteins on the cell surface membrane is discussed.

  14. Prediction of the adhesive behavior of bio-inspired functionally graded materials against rough surfaces

    Directory of Open Access Journals (Sweden)

    Chen Peijian

    2014-06-01

    Full Text Available Roughness effect and adhesion properties are important characteristics to be accessed in the development of functionally graded materials for biological and biomimetic applications, particularly for the hierarchical composition in biomimetic gecko robot. A multi-asperities adhesion model to predict the adhesive forces is presented in this work. The effect of surface roughness and graded material properties, which significantly alter the adhesive strength between contact bodies, can be simultaneously considered in the generalized model. It is found that proper interfacial strength can be controlled by adjusting surface roughness σ / R, graded exponent k and material parameter E*R / Δγ. The results should be helpful in the design of new biomimetic materials and useful in application of micro functional instruments.

  15. Poly(vinyl alcohol)-micropatterned surfaces for manipulation of mesenchymal stem cell functions.

    Science.gov (United States)

    Chen, Guoping

    2014-01-01

    Micropatterning is a useful method to study the effects of biological and physical cues on cell functions. Various micropatterning methods have been developed for investigation of cell-cell interaction and cell-material interaction. As one of the potent methods, poly(vinyl alcohol) (PVA)-based micropatterning has been used to array cells in a pre-designed manner for a long-term cell culture. Cell population and single cell arrays can be formed in the micropatterned surfaces. The micropatterned surfaces have used to generate a gradient cell density, different degree of cell spreading, protrusion and cell-cell interaction and different geometry to investigate their effects on the differentiation of bone marrow-derived mesenchymal stem cells. This chapter highlights the latest development of PVA-based micropatterning and its application for manipulation of stem cell functions. Copyright © 2014 Elsevier Inc. All rights reserved.

  16. Comparison of bacterial cells and amine-functionalized abiotic surfaces as support for Pd nanoparticle synthesis

    DEFF Research Database (Denmark)

    De Corte, Simon; Bechstein, Stefanie; Lokanathan, Arcot R.

    2013-01-01

    An increasing demand for catalytic Pd nanoparticles has motivated the search for sustainable production methods. An innovative approach uses bacterial cells as support material for synthesizing Pd nanoparticles by reduction of Pd(II) with e.g. hydrogen or formate. Nevertheless, drawbacks...... nanoparticles, and that abiotic surfaces could support the Pd particle synthesis as efficiently as bacteria. In this study, we explore the possibility of replacing bacteria with amine-functionalized materials, and we compare different functionalization strategies. Pd nanoparticles formed on the support...... on these surfaces was higher than for Pd particles formed on Shewanella oneidensis cells. Smaller Pd nanoparticles generally have better catalytic properties, and previous studies have shown that the particle size can be lowered by increasing the amount of support material used during Pd particle formation. However...

  17. Solubility studies of inorganic–organic hybrid nanoparticle photoresists with different surface functional groups

    KAUST Repository

    Li, Li

    2016-01-01

    © 2016 The Royal Society of Chemistry. The solubility behavior of Hf and Zr based hybrid nanoparticles with different surface ligands in different concentrations of photoacid generator as potential EUV photoresists was investigated in detail. The nanoparticles regardless of core or ligand chemistry have a hydrodynamic diameter of 2-3 nm and a very narrow size distribution in organic solvents. The Hansen solubility parameters for nanoparticles functionalized with IBA and 2MBA have the highest contribution from the dispersion interaction than those with tDMA and MAA, which show more polar character. The nanoparticles functionalized with unsaturated surface ligands showed more apparent solubility changes after exposure to DUV than those with saturated ones. The solubility differences after exposure are more pronounced for films containing a higher amount of photoacid generator. The work reported here provides material selection criteria and processing strategies for the design of high performance EUV photoresists.

  18. Evaluation of optical functional surfaces on the injection moulding insert by micro milling process

    DEFF Research Database (Denmark)

    Li, Dongya; Davoudinejad, Ali; Zhang, Yang

    2017-01-01

    This study presents the optimization of micro milling process for manufacturing injection moulding inserts with an optical functionalsurface. The objective is the optimal surface functionality. Micro ridges were used as the microstructures to realize the function to generate contrast between...... orthogonally textured areas by reflecting light in different directions. In order to maximize the contrast,a sample was machined with the same structures and dimensions, according to a Design of Experiments (DOEs) to optimize the milling parameters by considering the contrast as a response. The contrast...

  19. Surface functionalization of titanium dioxide nanoparticles: Photo-stability and reactive oxygen species (ROS) generation

    Science.gov (United States)

    Louis, Kacie M.

    Metal oxide nanoparticles are becoming increasingly prevalent in society for applications of sunscreens, cosmetics, paints, biomedical imaging, and photovoltaics. Due to the increased surface area to volume ratio of nanoparticles compared to bulk materials, it is important to know the health and safety impacts of these materials. One mechanism of toxicity of nominally "safe" materials such as TiO 2 is through the photocatalytic generation of reactive oxygen species (ROS). ROS production and ligand degradation can affect the bioavailability of these particles in aqueous organisms. We have investigated ROS generation by functionalized TiO2 nanoparticles and its influence on aggregation and bioavailability and toxicity to zebrafish embryos/larvae. For these studies we investigated anatase TiO2 nanoparticles. For application purposes and solution stability, the TiO2 nanoparticles were functionalized with a variety of ligands such as citrate, 3,4-dihydroxybenzaldehyde, and ascorbate. We quantitatively examined the amount of ROS produced in aqueous solution using fluorescent probes and see that more ROS is produced under UV light than in the dark control. Our measurements show that TiO2 toxicity reaches a maximum for nanoparticles with smaller diameters, and is correlated with surface area dependent changes in ROS generation. In an effort to reduce toxicity through control of the surface and surface ligands, we synthesized anatase nanoparticles of different sizes, functionalized them with different ligands, and examined the resulting ROS generation and ligand stability. Using a modular ligand containing a hydrophobic inner region and a hydrophilic outer region, we synthesized water-stable nanoparticles, via two different chemical reactions, having much-reduced ROS generation and thus reduced toxicity. These results suggest new strategies for making safer nanoparticles while still retaining their desired properties. We also examine the degradation of the different ligands

  20. Physico-chemical characterization of ultra thin films of functional supramolecular systems on surfaces

    OpenAIRE

    Spampinato, Valentina

    2012-01-01

    The aim of this PhD thesis is the development of new metodologies for surface anchoring of molecular and supramolecular systems for applications in molecular electronics and photonics, and for preparation of devices for molecular recognition. The systems are made up, as usually, of hybrid systems, divided in two parts, a molecular one and a solid support. The molecular part performs the desired function, while the solid support (metal or semiconductor on which the molecules are bound) all...

  1. Surface functionalization of epitaxial graphene on SiC by ion irradiation for gas sensing application

    International Nuclear Information System (INIS)

    Kaushik, Priya Darshni; Ivanov, Ivan G.; Lin, Pin-Cheng; Kaur, Gurpreet; Eriksson, Jens; Lakshmi, G.B.V.S.; Avasthi, D.K.; Gupta, Vinay; Aziz, Anver; Siddiqui, Azher M.; Syväjärvi, Mikael; Yazdi, G. Reza

    2017-01-01

    Highlights: • For the first time the gas sensing application of SHI irradiated epitaxial graphene on SiC is explored. • Surface morphology of irradiated graphene layers showed graphene folding, hillocks, and formation of wrinkles. • Existence of an optimal fluence which maximize the gas sensing response towards NO 2 and NH 3 gases. - Abstract: In this work, surface functionalization of epitaxial graphene grown on silicon carbide was performed by ion irradiation to investigate their gas sensing capabilities. Swift heavy ion irradiation using 100 MeV silver ions at four varying fluences was implemented on epitaxial graphene to investigate morphological and structural changes and their effects on the gas sensing capabilities of graphene. Sensing devices are expected as one of the first electronic applications using graphene and most of them use functionalized surfaces to tailor a certain function. In our case, we have studied irradiation as a tool to achieve functionalization. Morphological and structural changes on epitaxial graphene layers were investigated by atomic force microscopy, Raman spectroscopy, Raman mapping and reflectance mapping. The surface morphology of irradiated graphene layers showed graphene folding, hillocks, and formation of wrinkles at highest fluence (2 × 10 13 ions/cm 2 ). Raman spectra analysis shows that the graphene defect density is increased with increasing fluence, while Raman mapping and reflectance mapping show that there is also a reduction of monolayer graphene coverage. The samples were investigated for ammonia and nitrogen dioxide gas sensing applications. Sensors fabricated on pristine and irradiated samples showed highest gas sensing response at an optimal fluence. Our work provides new pathways for introducing defects in controlled manner in epitaxial graphene, which can be used not only for gas sensing application but also for other applications, such as electrochemical, biosensing, magnetosensing and spintronic

  2. Investigation of peptide based surface functionalization for copper ions detection using an ultrasensitive mechanical microresonator

    DEFF Research Database (Denmark)

    Cagliani, Alberto; Fischer, Lee MacKenzie; Rasmussen, Jakob Lyager

    2011-01-01

    In the framework of developing a portable label-free sensor for multi arrayed detection of heavy metals in drinking water, we present a mechanical resonator-based copper ions sensor, which uses a recently synthesized peptide Cysteine–Glycine–Glycine–Histidine (CGGH) and the l-Cysteine (Cys) peptide...... devices to detect a concentration of 10μM of copper in water, we regenerate the surface by removing the copper ions from the functionalization layer using EDTA....

  3. Calculating the SnS(010) surface electronic structure using the green function method

    Science.gov (United States)

    Jahangirli, Z. A.

    2011-08-01

    The electronic structure of the (010) surface in a layered SnS semiconductor terminating with Sn and S atomic planes is calculated by the Green function method. The electronic structure of a perfect crystal is calculated according to the linear combination of atomic orbitals (LCAO) using Slater s-, p-, and d-orbitals. Defect-induced changes in the density of states and the origin and orbital composition of electronic states in the band gap are discussed.

  4. Solution of volume-surface integral equations using higher-order hierarchical Legendre basis functions

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Meincke, Peter; Breinbjerg, Olav

    2007-01-01

    The problem of electromagnetic scattering by composite metallic and dielectric objects is solved using the coupled volume-surface integral equation (VSIE). The method of moments (MoM) based on higher-order hierarchical Legendre basis functions and higher-order curvilinear geometrical elements...... with the analytical Mie series solution. Scattering by more complex metal-dielectric objects are also considered to compare the presented technique with other numerical methods....

  5. Surface functionalization of epitaxial graphene on SiC by ion irradiation for gas sensing application

    Energy Technology Data Exchange (ETDEWEB)

    Kaushik, Priya Darshni, E-mail: kaushik.priyadarshni@gmail.com [Department of Physics, Chemistry and Biology, Linköping University, SE-58183 Linköping (Sweden); Department of Physics, Jamia Millia Islamia, New Delhi, 110025 (India); Ivanov, Ivan G.; Lin, Pin-Cheng [Department of Physics, Chemistry and Biology, Linköping University, SE-58183 Linköping (Sweden); Kaur, Gurpreet [Department of Physics and Astrophysics, University of Delhi, Delhi, 110007 (India); Eriksson, Jens [Department of Physics, Chemistry and Biology, Linköping University, SE-58183 Linköping (Sweden); Lakshmi, G.B.V.S. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi, 110067 (India); Avasthi, D.K. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi, 110067 (India); Amity Institute of Nanotechnology, Noida 201313 (India); Gupta, Vinay [Department of Physics and Astrophysics, University of Delhi, Delhi, 110007 (India); Aziz, Anver; Siddiqui, Azher M. [Department of Physics, Jamia Millia Islamia, New Delhi, 110025 (India); Syväjärvi, Mikael [Department of Physics, Chemistry and Biology, Linköping University, SE-58183 Linköping (Sweden); Yazdi, G. Reza, E-mail: yazdi@ifm.liu.se [Department of Physics, Chemistry and Biology, Linköping University, SE-58183 Linköping (Sweden)

    2017-05-01

    Highlights: • For the first time the gas sensing application of SHI irradiated epitaxial graphene on SiC is explored. • Surface morphology of irradiated graphene layers showed graphene folding, hillocks, and formation of wrinkles. • Existence of an optimal fluence which maximize the gas sensing response towards NO{sub 2} and NH{sub 3} gases. - Abstract: In this work, surface functionalization of epitaxial graphene grown on silicon carbide was performed by ion irradiation to investigate their gas sensing capabilities. Swift heavy ion irradiation using 100 MeV silver ions at four varying fluences was implemented on epitaxial graphene to investigate morphological and structural changes and their effects on the gas sensing capabilities of graphene. Sensing devices are expected as one of the first electronic applications using graphene and most of them use functionalized surfaces to tailor a certain function. In our case, we have studied irradiation as a tool to achieve functionalization. Morphological and structural changes on epitaxial graphene layers were investigated by atomic force microscopy, Raman spectroscopy, Raman mapping and reflectance mapping. The surface morphology of irradiated graphene layers showed graphene folding, hillocks, and formation of wrinkles at highest fluence (2 × 10{sup 13} ions/cm{sup 2}). Raman spectra analysis shows that the graphene defect density is increased with increasing fluence, while Raman mapping and reflectance mapping show that there is also a reduction of monolayer graphene coverage. The samples were investigated for ammonia and nitrogen dioxide gas sensing applications. Sensors fabricated on pristine and irradiated samples showed highest gas sensing response at an optimal fluence. Our work provides new pathways for introducing defects in controlled manner in epitaxial graphene, which can be used not only for gas sensing application but also for other applications, such as electrochemical, biosensing, magnetosensing and

  6. Determination of surface functional groups on mechanochemically activated carbon cloth by Boehm method

    Directory of Open Access Journals (Sweden)

    Đukić Anđelka B.

    2014-01-01

    Full Text Available In order to improve sorption properties of activated carbon cloth that can be used for wastewater purification, mechanochemical activation was performed in both inert and air atmosphere. Boehm method was used to follow the changes in the number and types of surface groups induced by mechanical milling. The number of the base groups of 0,2493 mmol/g is significantly smaller than the total amount of acidic functional groups, 2,5093 mmol/g. Among the acidic groups present on the surface, the most represented are phenolic groups (2.3846 mmol/g , ie . > 95 % , the carboxylic groups are present far less (0.1173 mmol /g, ie. 4.5 %, while the presence of the lactone group on the surface of ACC is negligible (0.0074 mmol/g ie. under 0.3 %. Mechanochemical activation lead to an increase in the number of acidic and basic groups on the surface of the ACC. The milling in inert atmosphere has dominant effect with respect to the changes in the total number of basic functional groups (compared to milling in an air atmosphere: the number of basic groups of the ACC was 0.8153 mmol/g milled under argon, 0.7933 mmol/g in the air; the number of acidic groups is 2.9807 mmol/g for a sample milled under argon and 3.5313 mmol/g for one milled in the air.

  7. Functionalization of SU-8 photoresist surfaces with IgG proteins

    International Nuclear Information System (INIS)

    Blagoi, Gabriela; Keller, Stephan; Johansson, Alicia; Boisen, Anja; Dufva, Martin

    2008-01-01

    The negative epoxy-based photoresist SU-8 has a variety of applications within microelectromechanical systems (MEMS) and lab-on-a-chip systems. Here, several methods to functionalize SU-8 surfaces with IgG proteins were investigated. Fluorescent labeled proteins and fluorescent sandwich immunoassays were employed to characterize the binding efficiency of model proteins to bare SU-8 surface, SU-8 treated with cerium ammonium nitrate (CAN) etchant and CAN treated surfaces modified by aminosilanization. The highest binding capacity of antibodies was observed on bare SU-8. This explains why bare SU-8 in a functional fluorescent sandwich immunoassay detecting C-reactive protein (CRP) gave twice as high signal as compared with the other two surfaces. Immunoassays performed on bare SU-8 and CAN treated SU-8 resulted in detection limits of CRP of 30 and 80 ng/ml respectively which is sufficient for detecting CRP in clinical samples, where concentrations of 3-10 μg/ml are normal for healthy individuals. In conclusion, bare SU-8 and etched SU-8 can be modified with antibodies by a simple adsorption procedure which simplifies building lab-on-a-chip systems in SU-8. Additionally, we report the fabrication process and use of microwells created in a SU-8 layer with the same dimensions as a standard microscope glass slide that could fit into fluorescent scanners. The SU-8 microwells minimize the reagent consumption and are straightforward to handle compared to SU-8 coated microscope slides

  8. Roles of acidic functional groups of carbon fiber surfaces in enhancing interfacial adhesion behavior

    International Nuclear Information System (INIS)

    Park, Soo-Jin; Kim, Byung-Joo

    2005-01-01

    The gas phase ozone treatment was used as a method to bind acidic oxygen functional groups on carbon fiber surfaces. The ozone treatment on carbon fibers was varied with the ozone concentration and treatment time. Surface analyses of the carbon fibers before and after treatments were performed by FT-IR, X-ray photoelectron spectrometer (XPS), and dynamic contact angle measurements. Mechanical interfacial properties of the fibers/polymer composites were investigated by using critical stress intensity factor (K IC ) and critical energy release rate (G IC ) measurements. From the results of FT-IR and XPS, it was observed that the oxygen functional groups, such as -OH, O-C=O, C=O, and C-O, were attached on the carbon fiber surfaces after the ozone treatment. The mechanical interfacial properties of the composites also showed higher values than those of untreated composites. Ozone treatment is attributed to the increase of both the acidic functional groups and the degree of adhesion at interfaces between the fibers and polymeric resin in composites

  9. Surface functionalization of 3D-printed plastics via initiated chemical vapor deposition

    Directory of Open Access Journals (Sweden)

    Christine Cheng

    2017-08-01

    Full Text Available 3D printing is a useful fabrication technique because it offers design flexibility and rapid prototyping. The ability to functionalize the surfaces of 3D-printed objects allows the bulk properties, such as material strength or printability, to be chosen separately from surface properties, which is critical to expanding the breadth of 3D printing applications. In this work, we studied the ability of the initiated chemical vapor deposition (iCVD process to coat 3D-printed shapes composed of poly(lactic acid and acrylonitrile butadiene styrene. The thermally insulating properties of 3D-printed plastics pose a challenge to the iCVD process due to large thermal gradients along the structures during processing. In this study, processing parameters such as the substrate temperature and the filament temperature were systematically varied to understand how these parameters affect the uniformity of the coatings along the 3D-printed objects. The 3D-printed objects were coated with both hydrophobic and hydrophilic polymers. Contact angle goniometry and X-ray photoelectron spectroscopy were used to characterize the functionalized surfaces. Our results can enable the use of iCVD to functionalize 3D-printed materials for a range of applications such as tissue scaffolds and microfluidics.

  10. SEPARATION OF CELL POPULATIONS BY SUPER-PARAMAGNETIC PARTICLES WITH CONTROLLED SURFACE FUNCTIONALITY

    Directory of Open Access Journals (Sweden)

    Lootsik M. D.

    2014-02-01

    Full Text Available The recognition and isolation of specific mammalian cells by the biocompatible polymer coated super-paramagnetic particles with determined surface functionality were studied. The method of synthesis of nanoscaled particles on a core of iron III oxide (Fe2O3, magemit coated with a polymer shell containing reactive oligoperoxide groups for attachment of ligands is described. By using the developed superparamagnetic particles functionalized with peanut agglutinin (PNA we have separated the sub-populations of PNA+ and PNA– cells from ascites of murine Nemeth-Kellner lymphoma. In another type of experiment, the particles were opsonized with proteins of the fetal calf serum that improved biocompatibility of the particles and their ingestion by cultivated murine macrophages J774.2. Macrophages loaded with the particles were effeciently separated from the particles free cells by using the magnet. Thus, the developed surface functionalized superparamagnetic particles showed to be a versatile tool for cell separation independent on the mode of particles’ binding with cell surface or their engulfment by the targeted cells.

  11. Surface functionalization of 3D-printed plastics via initiated chemical vapor deposition.

    Science.gov (United States)

    Cheng, Christine; Gupta, Malancha

    2017-01-01

    3D printing is a useful fabrication technique because it offers design flexibility and rapid prototyping. The ability to functionalize the surfaces of 3D-printed objects allows the bulk properties, such as material strength or printability, to be chosen separately from surface properties, which is critical to expanding the breadth of 3D printing applications. In this work, we studied the ability of the initiated chemical vapor deposition (iCVD) process to coat 3D-printed shapes composed of poly(lactic acid) and acrylonitrile butadiene styrene. The thermally insulating properties of 3D-printed plastics pose a challenge to the iCVD process due to large thermal gradients along the structures during processing. In this study, processing parameters such as the substrate temperature and the filament temperature were systematically varied to understand how these parameters affect the uniformity of the coatings along the 3D-printed objects. The 3D-printed objects were coated with both hydrophobic and hydrophilic polymers. Contact angle goniometry and X-ray photoelectron spectroscopy were used to characterize the functionalized surfaces. Our results can enable the use of iCVD to functionalize 3D-printed materials for a range of applications such as tissue scaffolds and microfluidics.

  12. Amino-functionalized surface modification of polyacrylonitrile hollow fiber-supported polydimethylsiloxane membranes

    Science.gov (United States)

    Hu, Leiqing; Cheng, Jun; Li, Yannan; Liu, Jianzhong; Zhou, Junhu; Cen, Kefa

    2017-08-01

    This study aimed to improve surface polarity of polydimethylsiloxane (PDMS) membranes and provide surface active sites which were easy to react with other chemicals. 3-Aminopropyltriethoxysilane (APTES) containing an amino group was introduced into a PDMS membrane by crosslinking to prepare polyacrylonitrile hollow fiber-supported PDMS membranes with an amino-functionalized surface. Fourier transform infrared and X-ray photoelectron spectroscopic analyses proved the existence of APTES and its amino group in the PDMS membrane. The concentration of N atoms on the PDMS membrane surface reached ∼6% when the mass ratio of APTES/PDMS oligomer in the PDMS coating solution was increased to 4/3. The water contact angle decreased from ∼114° to ∼87.5°, indicating the improved surface polarization of the PDMS membrane. The density and swelling degree of the PDMS membrane decreased and increased, respectively, with increasing APTES content in PDMS. This phenomenon increased CO2 permeability and decreased CO2/H2 selectivity, CO2/CH4 selectivity, and CO2/N2 selectivity. When the mass ratio of APTES/PDMS oligomer was increased from 0 to 4/3, the CO2 permeation rate of the hollow fiber-supported PDMS membranes initially decreased from ∼2370 GPU to ∼860 GPU and then increased to ∼2000 GPU due to the change in coating solution viscosity.

  13. Binary Pseudo-Random Gratings and Arrays for Calibration of Modulation Transfer Functions of Surface Profilometers

    Energy Technology Data Exchange (ETDEWEB)

    Barber, Samuel K.; Anderson, Erik D.; Cambie, Rossana; McKinney, Wayne R.; Takacs, Peter Z.; Stover, John C.; Voronov, Dmitriy L.; Yashchuk, Valeriy V.

    2009-09-11

    A technique for precise measurement of the modulation transfer function (MTF), suitable for characterization of a broad class of surface profilometers, is investigated in detail. The technique suggested in [Proc. SPIE 7077-7, (2007), Opt. Eng. 47(7), 073602-1-5 (2008)]is based on use of binary pseudo-random (BPR) gratings and arrays as standard MTF test surfaces. Unlike most conventional test surfaces, BPR gratings and arrays possess white-noise-like inherent power spectral densities (PSD), allowing the direct determination of the one- and two-dimensional MTF, respectively, with a sensitivity uniform over the entire spatial frequency range of a profiler. In the cited work, a one dimensional realization of the suggested method based on use of BPR gratings has been demonstrated. Here, a high-confidence of the MTF calibration technique is demonstrated via cross comparison measurements of a number of two dimensional BPR arrays using two different interferometric microscopes and a scatterometer. We also present the results of application of the experimentally determined MTF correction to the measurement taken with the MicromapTM-570 interferometric microscope of the surface roughness of a super-polished test mirror. In this particular case, without accounting for the instrumental MTF, the surface rms roughness over half of the instrumental spatial frequency bandwidth would be underestimated by a factor of approximately 1.4.

  14. Hydrophobic surface functionalization of lignocellulosic jute fabrics by enzymatic grafting of octadecylamine.

    Science.gov (United States)

    Dong, Aixue; Fan, Xuerong; Wang, Qiang; Yu, Yuanyuan; Cavaco-Paulo, Artur

    2015-08-01

    Enzymatic grafting of synthetic molecules onto lignins provides a mild and eco-friendly alternative for the functionalization of lignocellulosic materials. In this study, laccase-mediated grafting of octadecylamine (OA) onto lignin-rich jute fabrics was investigated for enhancing the surface hydrophobicity. First, the lignins in jute fabrics were isolated and analyzed in the macromolecular level by MALDI-TOF MS, (1)H NMR, (13)C NMR, and HSQC-NMR. Then, the surface of jute fabrics was characterized by FT-IR, XPS, and SEM. Subsequently, the nitrogen content of jute fabrics was determined by the micro-Kjeldahl method, and the grafting percentage (Gp) and grafting efficiency (GE) of the enzymatic reaction were calculated. Finally, the surface hydrophobicity of the jute fabrics was estimated by contact angle and wetting time measurements. The results indicate that the OA monomers were successfully grafted onto the lignin moieties on the jute fiber surface by laccase with Gp and GE values of 0.712% and 10.571%, respectively. Moreover, the modified jute fabrics via OA-grafting showed an increased wetting time of 18.5 min and a contact angle of 116.72°, indicating that the surface hydrophobicity of the jute fabrics increased after the enzymatic grafting modification with hydrophobic OA molecules. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Tip-Sample Interactions as a Function of Distance on Insulating Surfaces

    Science.gov (United States)

    Hoffmann, Regina

    Recent advances in the measurement methods of scanning force microscopy (SFM) in the dynamic mode allow experimental access to site-specific short range forces. Either the tip is moved to a particular site, or the full three-dimensional frequency shift field of the oscillating tip is recorded while scanning a small surface area. Then the frequency shift is converted to force, and the long-range forces are fit by models and subtracted. The remaining short-range forces measured on a well- known surface CaF2 (111) can be used to learn more about the tip structure and chemical composition. On NaCl (001)-type crystal surfaces, where there is a complete symmetry of the local distribution of the positive and negative charge, the measurement of the force as a function of distance allows to unambiguously identify the positively and negatively charged sublattices on the surface. If additionally, the full three-dimensional force field is measured, information about the chemical nature of the tip-terminating cluster and about lateral forces are obtained. SFM measurements of site-specific force-distance curves further allow a deeper insight into mechanisms of energy dissipation at tips and surfaces.

  16. Amino-functionalized surface modification of polyacrylonitrile hollow fiber-supported polydimethylsiloxane membranes

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Leiqing; Cheng, Jun, E-mail: juncheng@zju.edu.cn; Li, Yannan; Liu, Jianzhong; Zhou, Junhu; Cen, Kefa

    2017-08-15

    Highlights: • Amino group was introduced to improve surface polarity of PDMS membrane. • The water contact angle of PDMS membrane decreased after the modification. • The concentration of N atom on surface of PDMS membrane reached up to ∼6%. • The density of PDMS membrane decreased while the swelling degree increased. • CO{sub 2} permeability increased while selectivity decreased after the modification. - Abstract: This study aimed to improve surface polarity of polydimethylsiloxane (PDMS) membranes and provide surface active sites which were easy to react with other chemicals. 3-Aminopropyltriethoxysilane (APTES) containing an amino group was introduced into a PDMS membrane by crosslinking to prepare polyacrylonitrile hollow fiber-supported PDMS membranes with an amino-functionalized surface. Fourier transform infrared and X-ray photoelectron spectroscopic analyses proved the existence of APTES and its amino group in the PDMS membrane. The concentration of N atoms on the PDMS membrane surface reached ∼6% when the mass ratio of APTES/PDMS oligomer in the PDMS coating solution was increased to 4/3. The water contact angle decreased from ∼114° to ∼87.5°, indicating the improved surface polarization of the PDMS membrane. The density and swelling degree of the PDMS membrane decreased and increased, respectively, with increasing APTES content in PDMS. This phenomenon increased CO{sub 2} permeability and decreased CO{sub 2}/H{sub 2} selectivity, CO{sub 2}/CH{sub 4} selectivity, and CO{sub 2}/N{sub 2} selectivity. When the mass ratio of APTES/PDMS oligomer was increased from 0 to 4/3, the CO{sub 2} permeation rate of the hollow fiber-supported PDMS membranes initially decreased from ∼2370 GPU to ∼860 GPU and then increased to ∼2000 GPU due to the change in coating solution viscosity.

  17. Amino-functionalized surface modification of polyacrylonitrile hollow fiber-supported polydimethylsiloxane membranes

    International Nuclear Information System (INIS)

    Hu, Leiqing; Cheng, Jun; Li, Yannan; Liu, Jianzhong; Zhou, Junhu; Cen, Kefa

    2017-01-01

    Highlights: • Amino group was introduced to improve surface polarity of PDMS membrane. • The water contact angle of PDMS membrane decreased after the modification. • The concentration of N atom on surface of PDMS membrane reached up to ∼6%. • The density of PDMS membrane decreased while the swelling degree increased. • CO 2 permeability increased while selectivity decreased after the modification. - Abstract: This study aimed to improve surface polarity of polydimethylsiloxane (PDMS) membranes and provide surface active sites which were easy to react with other chemicals. 3-Aminopropyltriethoxysilane (APTES) containing an amino group was introduced into a PDMS membrane by crosslinking to prepare polyacrylonitrile hollow fiber-supported PDMS membranes with an amino-functionalized surface. Fourier transform infrared and X-ray photoelectron spectroscopic analyses proved the existence of APTES and its amino group in the PDMS membrane. The concentration of N atoms on the PDMS membrane surface reached ∼6% when the mass ratio of APTES/PDMS oligomer in the PDMS coating solution was increased to 4/3. The water contact angle decreased from ∼114° to ∼87.5°, indicating the improved surface polarization of the PDMS membrane. The density and swelling degree of the PDMS membrane decreased and increased, respectively, with increasing APTES content in PDMS. This phenomenon increased CO 2 permeability and decreased CO 2 /H 2 selectivity, CO 2 /CH 4 selectivity, and CO 2 /N 2 selectivity. When the mass ratio of APTES/PDMS oligomer was increased from 0 to 4/3, the CO 2 permeation rate of the hollow fiber-supported PDMS membranes initially decreased from ∼2370 GPU to ∼860 GPU and then increased to ∼2000 GPU due to the change in coating solution viscosity.

  18. Functional surface engineering of C-dots for fluorescent biosensing and in vivo bioimaging.

    Science.gov (United States)

    Ding, Changqin; Zhu, Anwei; Tian, Yang

    2014-01-21

    Nanoparticles are promising scaffolds for applications such as imaging, chemical sensors and biosensors, diagnostics, drug delivery, catalysis, energy, photonics, medicine, and more. Surface functionalization of nanoparticles introduces an additional dimension in controlling nanoparticle interfacial properties and provides an effective bridge to connect nanoparticles to biological systems. With fascinating photoluminescence properties, carbon dots (C-dots), carbon-containing nanoparticles that are attracting considerable attention as a new type of quantum dot, are becoming both an important class of imaging probes and a versatile platform for engineering multifunctional nanosensors. In order to transfer C-dots from proof-of-concept studies toward real world applications such as in vivo bioimaging and biosensing, careful design and engineering of C-dot probes is becoming increasingly important. A comprehensive knowledge of how C-dot surfaces with various properties behave is essential for engineering C-dots with useful imaging properties such as high quantum yield, stability, and low toxicity, and with desirable biosensing properties such as high selectivity, sensitivity, and accuracy. Several reviews in recent years have reported preparation methods and properties of C-dots and described their application in biosensors, catalysis, photovoltatic cells, and more. However, no one has yet systematically summarized the surface engineering of C-dots, nor the use of C-dots as fluorescent nanosensors or probes for in vivo imaging in cells, tissues, and living organisms. In this Account, we discuss the major design principles and criteria for engineering the surface functionality of C-dots for biological applications. These criteria include brightness, long-term stability, and good biocompatibility. We review recent developments in designing C-dot surfaces with various functionalities for use as nanosensors or as fluorescent probes with fascinating analytical performance

  19. In vitro characterization of two different atmospheric plasma jet chemical functionalizations of titanium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Mussano, F., E-mail: federico.mussano@unito.it [CIR Dental School, Department of Surgical Sciences UNITO, via Nizza 230, 10126, Turin (Italy); Genova, T. [CIR Dental School, Department of Surgical Sciences UNITO, via Nizza 230, 10126, Turin (Italy); Department of Life Sciences and Systems Biology, UNITO, via Accademia Albertina 13, 10123, Turin (Italy); Verga Falzacappa, E. [Department of Molecular Science and Nanosystems, UNIVE, Via Torino 155, 30170, Venezia (Italy); Nadir srl, Via Torino 155, 30170 Venezia (Italy); Scopece, P. [Nadir srl, Via Torino 155, 30170 Venezia (Italy); Munaron, L. [Department of Life Sciences and Systems Biology, UNITO, via Accademia Albertina 13, 10123, Turin (Italy); Centre for Nanostructured Interfaces and Surfaces (NIS) (Italy); Rivolo, P.; Mandracci, P. [Politecnico di Torino, Department of Applied Science and Technology, Materials and Microsoystems Laboratory (ChiLab), Corso Duca degli Abruzzi 24, 10129, Torino (Italy); Benedetti, A. [Department of Molecular Science and Nanosystems, UNIVE, Via Torino 155, 30170, Venezia (Italy); Carossa, S. [CIR Dental School, Department of Surgical Sciences UNITO, via Nizza 230, 10126, Turin (Italy); Patelli, A. [Department of Physics and Astronomy, UNIPD, via Marzolo 8, 35122 Padova (Italy)

    2017-07-01

    Highlights: • NH{sub 2}-Ti and COOH/R-Ti obtained via atmospheric plasma jet RF-APPJ portable equipment. • Higher quantity of adsorbed proteins and improved cell adhesion on treated surfaces. • More tapered and elongated cells on NH{sub 2}-Ti compared to COOH/R-Ti. • Higher osteocalcin expression on NH{sub 2}-Ti. - Abstract: Plasma surface activation and plasma polymers deposition are promising technologies capable to modulate biologically relevant surface features of biomaterials. The purpose of this study was to evaluate the biological effects of two different surface modifications, i.e. amine (NH{sub 2}-Ti) and carboxylic/esteric (COOH/R-Ti) functionalities obtained from 3-aminopropyltriethoxysilane (3-APTES) and methylmethacrylate (MMA) precursors, respectively, through an atmospheric plasma jet RF-APPJ portable equipment. The coatings were characterized by Scanning Electron Microscopy, FT-IR spectroscopy, XPS and surface energy calculations. Stability in water and after UV sterilization were also verified. The pre-osteoblastic murine cell line MC3T3-E1 was used to perform the in-vitro tests. The treated samples showed a higher quantity of adsorbed proteins and improved osteoblast cells adhesion on the surfaces compared to the pristine titanium, in particular the COOH/R-Ti led to a nearly two-fold improvement. Cell proliferation on coated samples was initially (at 24 h) lower than on titanium control, while, at 48 h, COOH/R-Ti reached the proliferation rate of pristine titanium. Cells grown on NH{sub 2}-Ti were more tapered and elongated in shape with lower areas than on COOH/R-Ti enriched surfaces. Finally, NH{sub 2}-Ti significantly enhanced osteocalcin production, starting from 14 days, while COOH/R-Ti had this effect only from 21 days. Notably, NH{sub 2}-Ti was more efficient than COOH/R-Ti at 21 days. The amine functionality elicited the most relevant osteogenic effect in terms of osteocalcin expression, thus establishing an interesting correlation

  20. Towards spatially smart abatement of human pharmaceuticals in surface waters: defining impact of sewage treatment plants on susceptible functions

    NARCIS (Netherlands)

    Gils, J.A.G.; Coppens, L.J.C.; Laak, ter T.L.; Raterman, B.W.; Wezel, van A.P.

    2015-01-01

    For human pharmaceuticals, sewage treatment plants (STPs) are a major point of entry to surface waters. The receiving waters provide vital functions. Modeling the impact of STPs on susceptible functions of the surface water system allows for a spatially smart implementation of abatement options at,

  1. Towards spatially smart abatement of human pharmaceuticals in surface waters : Defining impact of sewage treatment plants on susceptible functions

    NARCIS (Netherlands)

    Coppens, Lieke J C; van Gils, Jos A G; Ter Laak, Thomas L; Raterman, Bernard W; van Wezel, Annemarie P

    2015-01-01

    For human pharmaceuticals, sewage treatment plants (STPs) are a major point of entry to surface waters. The receiving waters provide vital functions. Modeling the impact of STPs on susceptible functions of the surface water system allows for a spatially smart implementation of abatement options at,

  2. Cells transplanted onto the surface of the glial scar reveal hidden potential for functional neural regeneration.

    Science.gov (United States)

    Sekiya, Tetsuji; Holley, Matthew C; Hashido, Kento; Ono, Kazuya; Shimomura, Koichiro; Horie, Rie T; Hamaguchi, Kiyomi; Yoshida, Atsuhiro; Sakamoto, Tatsunori; Ito, Juichi

    2015-06-30

    Cell transplantation therapy has long been investigated as a therapeutic intervention for neurodegenerative disorders, including spinal cord injury, Parkinson's disease, and amyotrophic lateral sclerosis. Indeed, patients have high hopes for a cell-based therapy. However, there are numerous practical challenges for clinical translation. One major problem is that only very low numbers of donor cells survive and achieve functional integration into the host. Glial scar tissue in chronic neurodegenerative disorders strongly inhibits regeneration, and this inhibition must be overcome to accomplish successful cell transplantation. Intraneural cell transplantation is considered to be the best way to deliver cells to the host. We questioned this view with experiments in vivo on a rat glial scar model of the auditory system. Our results show that intraneural transplantation to the auditory nerve, preceded by chondroitinase ABC (ChABC)-treatment, is ineffective. There is no functional recovery, and almost all transplanted cells die within a few weeks. However, when donor cells are placed on the surface of a ChABC-treated gliotic auditory nerve, they autonomously migrate into it and recapitulate glia- and neuron-guided cell migration modes to repair the auditory pathway and recover auditory function. Surface transplantation may thus pave the way for improved functional integration of donor cells into host tissue, providing a less invasive approach to rescue clinically important neural tracts.

  3. Surface and Interface Engineering of Conjugated Polymers and Nanomaterials in Applications of Supercapacitors and Surface-functionalization

    KAUST Repository

    Hou, Yuanfang

    2016-05-23

    . (iii) Another aspect about interface chemistry of direct functionalization of nanodiamond with maleimide has also been addressed. Functional nanodiamonds are promising candidates for extensive practical applications in surface science, photonics and nanomedicine. Here, a protocol of direct functionalization is described by which maleimide-derivatized substituents can be appended to the outer shell of thermally annealed nanodiamonds through Diels-Alder reaction. This protocol can be carried out in room temperature, ambient atmosphere, without catalyst, and provide functionalized nanodiamonds with good solubility in organic solution. Also, this method can be applied for other maleimide derivatives,e.g.m aleimide-fluorescene, which can be applied in fluorescence labeling, sensing, and drug delivery. A series of techniques, especially Fourier transform infrared spectroscopy (FTIR), and Solid State Nuclear Magnetic Resonance (SS-NMR) was conducted for the analysis of surface chemistry and the investigation of the two-point binding strategy in details.

  4. Evaluation of fitting functions for the representation of an O(3P)+H2 potential energy surface. I

    International Nuclear Information System (INIS)

    Wagner, A.F.; Schatz, G.C.; Bowman, J.M.

    1981-01-01

    The DIM surface of Whitlock, Muckerman, and Fisher for the O( 3 P)+H 2 system is used as a test case to evaluate the usefulness of a variety of fitting functions for the representation of potential energy surfaces. Fitting functions based on LEPS, BEBO, and rotated Morse oscillator (RMO) forms are examined. Fitting procedures are developed for combining information about a small portion of the surface and the fitting function to predict where on the surface more information must be obtained to improve the accuracy of the fit. Both unbiased procedures and procedures heavily biased toward the saddle point region of the surface are investigated. Collinear quasiclassical trajectory calculations of the reaction rate constant and one and three dimensional transition state theory rate constant calculations are performed and compared for selected fits and the exact DIM test surface. Fitting functions based on BEBO and RMO forms are found to give quite accurate results

  5. Operational accuracy and comparative persistent antigenicity of HRP2 rapid diagnostic tests for Plasmodium falciparum malaria in a hyperendemic region of Uganda

    Directory of Open Access Journals (Sweden)

    Odong George W

    2008-10-01

    Full Text Available Abstract Background Parasite-based diagnosis of malaria by microscopy requires laboratory skills that are generally unavailable at peripheral health facilities. Rapid diagnostic tests (RDTs require less expertise, but accuracy under operational conditions has not been fully evaluated in Uganda. There are also concerns about RDTs that use the antigen histidine-rich protein 2 (HRP2 to detect Plasmodium falciparum, because this antigen can persist after effective treatment, giving false positive test results in the absence of infection. An assessment of the accuracy of Malaria Pf™ immuno-chromatographic test (ICT and description of persistent antigenicity of HRP2 RDTs was undertaken in a hyperendemic area of Uganda. Methods Using a cross-sectional design, a total of 357 febrile patients of all ages were tested using ICT, and compared to microscopy as the gold standard reference. Two independent RDT readings were used to assess accuracy and inter-observer reliability. With a longitudinal design to describe persistent antigenicity of ICT and Paracheck, 224 children aged 6–59 months were followed up at 7-day intervals until the HRP2 antigens where undetectable by the RDTs. Results Of the 357 patients tested during the cross-sectional component, 40% (139 had positive blood smears for asexual forms of P. falciparum. ICT had an overall sensitivity of 98%, a specificity of 72%, a negative predictive value (NPV of 98% and a positive predictive value (PPV of 69%. ICT showed a high inter-observer reliability under operational conditions, with 95% of readings having assigned the same results (kappa statistics 0.921, p In children followed up after successful antimalaria treatment, the mean duration of persistent antigenicity was 32 days, and this duration varied significantly depending on pre-treatment parasitaemia. In patients with parasite density >50,000/μl, the mean duration of persistent antigenicity was 37 days compared to 26 days for parasitaemia

  6. Biomaterial design for specific cellular interactions: Role of surface functionalization and geometric features

    Science.gov (United States)

    Kolhar, Poornima

    The areas of drug delivery and tissue engineering have experienced extraordinary growth in recent years with the application of engineering principles and their potential to support and improve the field of medicine. The tremendous progress in nanotechnology and biotechnology has lead to this explosion of research and development in biomedical applications. Biomaterials can now be engineered at a nanoscale and their specific interactions with the biological tissues can be modulated. Various design parameters are being established and researched for design of drug-delivery carriers and scaffolds to be implanted into humans. Nanoparticles made from versatile biomaterial can deliver both small-molecule drugs and various classes of bio-macromolecules, such as proteins and oligonucleotides. Similarly in the field of tissue engineering, current approaches emphasize nanoscale control of cell behavior by mimicking the natural extracellular matrix (ECM) unlike, traditional scaffolds. Drug delivery and tissue engineering are closely connected fields and both of these applications require materials with exceptional physical, chemical, biological, and biomechanical properties to provide superior therapy. In the current study the surface functionalization and the geometric features of the biomaterials has been explored. In particular, a synthetic surface for culture of human embryonic stem cells has been developed, demonstrating the importance of surface functionalization in maintaining the pluripotency of hESCs. In the second study, the geometric features of the drug delivery carriers are investigated and the polymeric nanoneedles mediated cellular permeabilization and direct cytoplasmic delivery is reported. In the third study, the combined effect of surface functionalization and geometric modification of carriers for vascular targeting is enunciated. These studies illustrate how the biomaterials can be designed to achieve various cellular behaviors and control the

  7. Fresh and composted industrial sludge restore soil functions in surface soil of degraded agricultural land.

    Science.gov (United States)

    Arif, Muhammad Saleem; Riaz, Muhammad; Shahzad, Sher Muhammad; Yasmeen, Tahira; Ashraf, Muhammad; Siddique, Muhammad; Mubarik, Muhammad Salman; Bragazza, Luca; Buttler, Alexandre

    2018-04-01

    A field study was conducted to test the potential of 5-year consecutive application of fresh industrial sludge (FIS) and composted industrial sludge (CIS) to restore soil functions at surface (0-15cm) and subsurface (15-30cm) of the degraded agricultural land. Sludge amendments increased soil fertility parameters including total organic carbon (TOC), soil available nitrogen (SAN), soil available phosphorus (SAP) and soil available potassium (SAK) at 0-15cm depth. Soil enzyme activities i.e. dehydrogenase (DHA), β-glucosidase (BGA) and alkaline phosphatase (ALp) were significantly enhanced by FIS and CIS amendments in surface soil. However, urease activity (UA) and acid phosphatase (ACp) were significantly reduced compared to control soil. The results showed that sludge amendments significantly increased microbial biomass nitrogen (MBN) and microbial biomass phosphorus (MBP) at both soil depth, and soil microbial biomass carbon (MBC) only at 0-15cm depth. Significant changes were also observed in the population of soil culturable microflora (bacteria, fungi and actinomycetes) with CIS amendment in surface soil suggesting persistence of microbial activity owing to the addition of organic matter source. Sludge amendments significantly reduced soil heavy metal concentrations at 0-15cm depth, and the effect was more pronounced with CIS compared to unamended control soil. Sludge amendments generally had no significant impact on soil heavy metal concentrations in subsoil. Agronomic viability test involving maize was performed to evaluate phytotoxicity of soil solution extract at surface and sub-surface soil. Maize seeds grown in solution extract (0-15cm) from sludge treated soil showed a significant increase of relative seed germination (RSG), relative root growth (RRG) and germination index (GI). These results suggested that both sludge amendments significantly improved soil properties, however, the CIS amendment was relatively more effective in restoring soil functions

  8. Surface-enhanced Raman spectroscopy on laser-engineered ruthenium dye-functionalized nanoporous gold

    Energy Technology Data Exchange (ETDEWEB)

    Schade, Lina [Department of Chemistry, Universität Duisburg-Essen, 45117 Essen (Germany); Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 47057 Duisburg (Germany); Franzka, Steffen [Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 47057 Duisburg (Germany); Interdisciplinary Center for Analytics on the Nanoscale (ICAN), University of Duisburg-Essen, 47047 Duisburg (Germany); Biener, Monika; Biener, Jürgen [Nanoscale Synthesis and Characterization Laboratory, Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA 94550 (United States); Hartmann, Nils, E-mail: nils.hartmann@uni-due.de [Department of Chemistry, Universität Duisburg-Essen, 45117 Essen (Germany); Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 47057 Duisburg (Germany); Interdisciplinary Center for Analytics on the Nanoscale (ICAN), University of Duisburg-Essen, 47047 Duisburg (Germany)

    2016-06-30

    Graphical abstract: - Highlights: • Photothermal laser processing is used to modify the surface structure of nanoporous gold. • Laser-fabricated structures exhibit pore sizes in the range from 25 nm to 200 nm and higher. • Ru-dye-functionalized surface structures are used in surface-enhanced Raman spectroscopy (SERS) studies. • Raman peak intensities of N719, a commercial Ru-dye, exhibit a strong dependence on the pore size. • Maximum Raman peak intensities are observed for small pore sizes close to 25 nm. - Abstract: Photothermal processing of nanoporous gold with a microfocused continuous-wave laser at λ = 532 nm provides a facile means in order engineer the pore and ligament size of nanoporous gold. In this report we take advantage of this approach in order to investigate the size-dependence of enhancement effects in surface-enhanced Raman spectroscopy (SERS). Surface structures with laterally varying pore sizes from 25 nm to ≥200 nm are characterized using scanning electron microscopy and then functionalized with N719, a commercial ruthenium complex, which is widely used in dye-sensitized solar cells. Raman spectroscopy reveals the characteristic spectral features of N719. Peak intensities strongly depend on the pore size. Highest intensities are observed on the native support, i.e. on nanoporous gold with pore sizes around 25 nm. These results demonstrate the particular perspectives of laser-fabricated nanoporous gold structures in fundamental SERS studies. In particular, it is emphasized that laser-engineered porous gold substrates represent a very well defined platform in order to study size-dependent effects with high reproducibility and precision and resolve conflicting results in previous studies.

  9. Automatic monitoring of ecosystem structure and functions using integrated low-cost near surface sensors

    Science.gov (United States)

    Kim, J.; Ryu, Y.; Jiang, C.; Hwang, Y.

    2016-12-01

    Near surface sensors are able to acquire more reliable and detailed information with higher temporal resolution than satellite observations. Conventional near surface sensors usually work individually, and thus they require considerable manpower from data collection through information extraction and sharing. Recent advances of Internet of Things (IoT) provides unprecedented opportunities to integrate various low-cost sensors as an intelligent near surface observation system for monitoring ecosystem structure and functions. In this study, we developed a Smart Surface Sensing System (4S), which can automatically collect, transfer, process and analyze data, and then publish time series results on public-available website. The system is composed of micro-computer Raspberry pi, micro-controller Arduino, multi-spectral spectrometers made from Light Emitting Diode (LED), visible and near infrared cameras, and Internet module. All components are connected with each other and Raspberry pi intelligently controls the automatic data production chain. We did intensive tests and calibrations in-lab. Then, we conducted in-situ observations at a rice paddy field and a deciduous broadleaf forest. During the whole growth season, 4S obtained landscape images, spectral reflectance in red, green, blue, and near infrared, normalized difference vegetation index (NDVI), fraction of photosynthetically active radiation (fPAR), and leaf area index (LAI) continuously. Also We compared 4S data with other independent measurements. NDVI obtained from 4S agreed well with Jaz hyperspectrometer at both diurnal and seasonal scales (R2 = 0.92, RMSE = 0.059), and 4S derived fPAR and LAI were comparable to LAI-2200 and destructive measurements in both magnitude and seasonal trajectory. We believe that the integrated low-cost near surface sensor could help research community monitoring ecosystem structure and functions closer and easier through a network system.

  10. Effect of a Dynamic Seating Surface on Postural Control and Function in Children with Cerebral Palsy

    DEFF Research Database (Denmark)

    Meyer, Erna Rosenlund; Trew, Lisa

    Purpose: The purpose was to investigate if a seating system involving a dynamic material covering the seat back and base improves postural control, alignment and function in children with cerebral palsy and to investigate consequences of adapting The Seated Postural Control Measure to a target...... group with multifunctional disabilities. Relevance: Developing sitting systems for disabled persons is of great importance to avoid sitting problems, to increase the level of functioning and postural control which will have an impact on their daily living and activities. This project takes its starting...... Ethical Committee. Outcome measures were Seated Postural Control Measure (SPCM), which was modified to meet the children’s needs, was used to measure alignment and function. Force Sensitive Applications (FSA) on the seat surfaces was used to measure postural movements and interface pressure. All tests...

  11. Simulation of surface dynamics during dissolution as a function of the surface orientation: Implications for non-constant dissolution rates

    Science.gov (United States)

    Godinho, J. R. A.; Piazolo, S.; Evans, L.

    2014-12-01

    An important problem in geochemistry is the understanding of how changes occurring on a surface during dissolution affect the variability of measured dissolution rates. In this study a new approach to study the effect of surface dynamics on dissolution rates is tested by coupling experimental data with a numerical model that simulates the retreat of surface profiles during dissolution. We present specific results from the simulation of dissolution of fluorite surfaces. The equations that determine the retreat of a surface are based on experimentally obtained equations that relate the retreat rate of a surface to a single variable, the crystallographic orientation of the surface. Our results show that depending on the starting orientation, different types of topography are developed, similar to those observed experimentally. During the initial dissolution phase, changes of topography are rapid and associated with fast dissolution rates. The progressively slower dissolution rates are coupled with the development of surface segments with orientations that dissolve at a slower rate. Consequently, the overall retreat rate of a profile decreases during the simulation, and tends to a near-constant value. The results show a close relationship between dissolution rates, surface orientation and surface dynamics, which suggests that the dissolution rate of a specific mineral phase is not constant but varies with dissolution time and surface structure. This variability needs to be considered in the evaluation of experimentally derived dissolution rates, future dissolution experiments, and predictive kinetic models of dissolution.

  12. THE FAINT END OF THE LUMINOSITY FUNCTION AND LOW SURFACE BRIGHTNESS GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Geller, Margaret J.; Kurtz, Michael J.; Fabricant, Daniel G. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Diaferio, Antonaldo [Dipartimento di Fisica Generale ' Amedeo Avogadro' , Universita degli Studi di Torino, via P. Giuria 1, 10125 Torino (Italy); Dell' Antonio, Ian P., E-mail: mgeller@cfa.harvard.edu, E-mail: mkurtz@cfa.harvard.edu, E-mail: dfabricant@cfa.harvard.edu, E-mail: adiaferio@cfa.harvard.edu, E-mail: ian@het.brown.edu [Department of Physics, Brown University, Box 1843, Providence, RI 02912 (United States)

    2012-04-15

    Smithsonian Hectospec Lensing Survey (SHELS) is a dense redshift survey covering a 4 deg{sup 2} region to a limiting R = 20.6. In the construction of the galaxy catalog and in the acquisition of spectroscopic targets, we paid careful attention to the survey completeness for lower surface brightness dwarf galaxies. Thus, although the survey covers a small area, it is a robust basis for computation of the slope of the faint end of the galaxy luminosity function to a limiting M{sub R} = -13.3 + 5log h. We calculate the faint-end slope in the R band for the subset of SHELS galaxies with redshifts in the range 0.02 {<=}z < 0.1, SHELS{sub 0.1}. This sample contains 532 galaxies with R < 20.6 and with a median surface brightness within the half-light radius of SB{sub 50,R} = 21.82 mag arcsec{sup -2}. We used this sample to make one of the few direct measurements of the dependence of the faint end of the galaxy luminosity function on surface brightness. For the sample as a whole the faint-end slope, {alpha} = -1.31 {+-} 0.04, is consistent with both the Blanton et al. analysis of the Sloan Digital Sky Survey and the Liu et al. analysis of the COSMOS field. This consistency is impressive given the very different approaches of these three surveys. A magnitude-limited sample of 135 galaxies with optical spectroscopic redshifts with mean half-light surface brightness, SB{sub 50,R} {>=} 22.5 mag arcsec{sup -2} is unique to SHELS{sub 0.1}. The faint-end slope is {alpha}{sub 22.5} = -1.52 {+-} 0.16. SHELS{sub 0.1} shows that lower surface brightness objects dominate the faint-end slope of the luminosity function in the field, underscoring the importance of surface brightness limits in evaluating measurements of the faint-end slope and its evolution.

  13. Accuracy of PfHRP2 versus Pf-pLDH antigen detection by malaria rapid diagnostic tests in hospitalized children in a seasonal hyperendemic malaria transmission area in Burkina Faso.

    Science.gov (United States)

    Maltha, Jessica; Guiraud, Issa; Lompo, Palpouguini; Kaboré, Bérenger; Gillet, Philippe; Van Geet, Chris; Tinto, Halidou; Jacobs, Jan

    2014-01-13

    In most sub-Saharan African countries malaria rapid diagnostic tests (RDTs) are now used for the diagnosis of malaria. Most RDTs used detect Plasmodium falciparum histidine-rich protein-2 (PfHRP2), though P. falciparum-specific parasite lactate dehydrogenase (Pf-pLDH)-detecting RDTs may have advantages over PfHRP2-detecting RDTs. Only few data are available on the use of RDTs in severe illness and the present study compared Pf-pLDH to PfHRP2-detection. Hospitalized children aged one month to 14 years presenting with fever or severe illness were included over one year. Venous blood samples were drawn for malaria diagnosis (microscopy and RDT), culture and complete blood count. Leftovers were stored at -80 °C and used for additional RDT analysis and PCR. An RDT targeting both PfHRP2 and Pf-pLDH was performed on all samples for direct comparison of diagnostic accuracy with microscopy as reference method. PCR was performed to explore false-positive RDT results. In 376 of 694 (54.2%) included children, malaria was microscopically confirmed. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value were 100.0, 70.9, 69.4 and 100.0%, respectively for PfHRP2-detection and 98.7, 94.0, 91.6 and 99.1%, respectively for Pf-pLDH-detection. Specificity and PPV were significantly lower for PfHRP2-detection (p <0.001). For both detection antigens, specificity was lowest for children one to five years and in the rainy season. PPV for both antigens was highest in the rainy season, because of higher malaria prevalence. False positive PfHRP2 results were associated with prior anti-malarial treatment and positive PCR results (98/114 (86.0%) samples tested). Among children presenting with severe febrile illness in a seasonal hyperendemic malaria transmission area, the present study observed similar sensitivity but lower specificity and PPV of PfHRP2 compared to Pf-pLDH-detection. Further studies should assess the diagnostic accuracy and safety of an

  14. Construction and surface/interface behavior of bio-functional surface layer by microwave-excited Ar/H2O plasma-induced polyethylene glycol polymerization

    Science.gov (United States)

    Shao, Z.; Ogino, A.; Nagatsu, M.

    2017-07-01

    Ar/H2O microwave-excited surface-wave plasma-induced grafting-polymerization and crosslinking technique was presented to construct a bio-functional surface layer. Optical emission spectroscopy was used to diagnose Ar/H2O plasma. The surface/interface behavior especially the aging effect of hydroxyl groups over the grafted PEG spacer layer was investigated by measuring water contact angle and X-ray photoelectron spectroscopy. The results demonstrate that the addition of water vapor into Ar plasma can optimize the concentration of hydroxyl functional groups on surface; grafted PEG spacer layer can provide a long-term hydrophilicity of PU films, and alleviate the aging effect of hydroxyl functional groups.

  15. Methane adsorption on the surface of a model of shale: A density functional theory study

    International Nuclear Information System (INIS)

    Zhu, Yuan-qiang; Su, Hong; Jing, Ya; Guo, Jianchun; Tang, Junlei

    2016-01-01

    Highlights: • The adsorption of methane on kerogen was investigated by DFT method with D3 dispersion correction. • Methane prefers to be adsorbed on the sites directly above the carbon atoms of the kerogen. • The interaction energy with BSSE corrections is around 14 kJ mol −1 . • RDG gradient isosurface depicted the van der Waals interactions between methane and kerogen. • The adsorption of methane on kerogen slightly depends upon the adsorption sites on kerogen as well as the orientations of methane. - Abstract: As a model of shale, one part of polycyclic aromatic ring was used to represent the kerogen surface with the structural heterogeneity. The adsorption mechanisms of methane on the surface of the kerogen were investigated by M06-2× functional with D3 dispersion correction. Nine stable adsorption sites and the orientations of methane (CH 4 ) on the surface of the kerogen were systematically considered. Information from different methods lead to the same conclusion that methane prefers to be adsorbed on the sites directly above the carbon atoms of the kerogen rather than above the center of the six-membered rings. The interactions between methane and the surface of the kerogen are the van der Waals interactions. The interaction energies with the basis set superposition error (BSSE) corrections are around 14 kJ mol −1 at the M06-2×-D3/Jun-cc-pVDZ level. The RDG scatter graphs and the RDG gradient isosurface further illustrate that the interactions between methane and the surface of the kerogen belong to the van der Waals interactions. The weak interactions indicate that the adsorption of methane on the surface of the kerogen is physical adsorption and it slightly depends upon the adsorption sites on kerogen as well as the orientations of methane. These results are helpful for the understanding of the microcosmic mechanism of methane–shale interactions and for the exploitation of shale gas.

  16. Rational Design of Peptide-Functionalized Surface Plasmon Resonance Sensor for Specific Detection of TNT Explosive

    Directory of Open Access Journals (Sweden)

    Jin Wang

    2017-09-01

    Full Text Available In this study, a rationally-designed 2,4,6-trinitrotoluene (TNT binding peptide derived from an amino acid sequence of the complementarity-determining region (CDR of an anti-TNT monoclonal antibody was used for TNT detection based on a maleimide-functionalized surface plasmon resonance (SPR sensor. By antigen-docking simulation and screening, the TNT binding candidate peptides were obtained as TNTHCDR1 derived from the heavy chain of CDR1, TNTHCDR2 derived from CDR2, and TNTHCDR3 from CDR3 of an anti-TNT antibody. The binding events between candidate peptides and TNT were evaluated using the SPR sensor by direct determination based on the 3-aminopropyltriethoxysilane (APTES surface. The TNT binding peptide was directly immobilized on the maleimide-functionalized sensor chip surface from N-γ-maleimidobutyryl-oxysuccinimide ester (GMBS. The results demonstrated that peptide TNTHCDR3 was identified and selected as a TNT binding peptide among the other two candidate peptides. Five kinds of TNT analogues were also investigated to testify the selectivity of TNT binding peptide TNTHCDR3. Furthermore, the results indicated that the APTES-GMBS-based SPR sensor chip procedure featured a great potential application for the direct detection of TNT.

  17. The Properties of Nano Silver (Ag-Geopolymer as Antibacterial Composite for Functional Surface Materials

    Directory of Open Access Journals (Sweden)

    Armayani. M

    2017-01-01

    Full Text Available The purpose of this research was to produce and characterize nano silver (Ag-geopolymer composite for functional surface materials. Geopolymer matrix was synthesized through alkali activation of metakaolin and nano silver was added into geopolymers paste with a mass of 0, 0.5 g, 1 g, 1.5 g and 2 g keeping the mass of metakaolin constant. The mixture was cured at 70°C/1 hour and stored for 7 days before conducting any measurements. The structure of the resulting composite was examined by using Rigaku Mini Flex II x-ray diffraction (XRD. Scanning Electron Microscopy (SEM coupled with Energy Dispersive Spectroscopy (EDS was used to examine the morphology of the composite surface as well as the capability of the composite to isolate the growth of bacteria. The thermal properties of composites in terms of their working temperature and enthalpy were examined by using Perkin Elmer Differential Scanning Calorimetry (DSC. The heat resistance of composite was observed through calcination at 750°C for 18 hours. The results indicate that the resulting composites were able resist up 750°C. SEM examinations showed that nano Ag-geopolymer composites were effectively restraining the growth of bacteria. It is suggested that nano Ag-geopolymer composites are suitable for functional surface applications such as floor and wall, kitchen ware utensils, hospital instruments, art and decoration materials.

  18. Functional levels of floor surface roughness for the prevention of slips and falls: clean-and-dry and soapsuds-covered wet surfaces.

    Science.gov (United States)

    Kim, In-Ju; Hsiao, Hongwei; Simeonov, Peter

    2013-01-01

    Literature has shown a general trend that slip resistance performance improves with floor surface roughness. However, whether slip resistance properties are linearly correlated with surface topographies of the floors or what roughness levels are required for effective slip resistance performance still remain to be answered. This pilot study aimed to investigate slip resistance properties and identify functional levels of floor surface roughness for practical design applications in reducing the risk of slip and fall incidents. A theory model was proposed to characterize functional levels of surface roughness of floor surfaces by introducing a new concept of three distinctive zones. A series of dynamic friction tests were conducted using 3 shoes and 9 floor specimens under clean-and-dry as well as soapsuds-covered slippery wet environments. The results showed that all the tested floor-shoe combinations provided sufficient slip resistances performance under the clean-and-dry condition. A significant effect of floor type (surface roughness) on dynamic friction coefficient (DFC) was found in the soapsuds-covered wet condition. As compared to the surface roughness effects, the shoe-type effects were relatively small. Under the soapsuds-covered wet condition, floors with 50 μm in Ra roughness scale seemed to represent an upper bound in the functional range of floor surface roughness for slip resistance because further increase of surface roughness provided no additional benefit. A lower bound of the functional range for slip resistance under the soapsuds-covered wet condition was estimated from the requirement of DFC > 0.4 at Ra ≅ 17 μm. Findings from this study may have potential safety implications in the floor surface design for reducing slip and fall hazards. Published by Elsevier Ltd.

  19. Surface functionalization of cellulose with poly(3-hexylthiophene) via novel oxidative polymerization.

    Science.gov (United States)

    Hai, Thien An Phung; Sugimoto, Ryuichi

    2018-01-01

    Surface functionalization of cellulose with poly(3-hexylthiophene) (P3HT) was conducted with FeCl 3 as an oxidant in three different solvents: acetonitrile, chloroform, and hexane. Of these three solvents, hexane best promoted the grafting P3HT to cellulose with a high grafting ratio and molecular weight. The maxima of the UV-vis absorption and fluorescent spectra, observed at around 500 and 600nm, respectively, represented the build-up of the conjugated chain length formed by the grafting of P3HT onto the cellulose surface. The HOMO level of cellulose as determined by photoemission yield spectroscopy decreased from 4.83 to 4.67eV after modification with P3HT. Grafting P3HT onto the surface of cellulose provided super-hydrophobic property with a lotus effect. The conductivity of cellulose also improved significantly, from 10 -9 to 10 -6 S/cm when P3HT was present on the surface. The thermal stability and crystallinity of cellulose decreased slightly upon graft polymerization with P3HT. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Adsorption of atomic nitrogen and oxygen on [Formula: see text] surface: a density functional theory study.

    Science.gov (United States)

    Breedon, M; Spencer, M J S; Yarovsky, I

    2009-04-08

    The adsorption of atomic nitrogen and oxygen on the ([Formula: see text]) crystal face of zinc oxide (ZnO) was studied. Binding energies, workfunction changes, vibrational frequencies, charge density differences and electron localization functions were calculated. It was elucidated that atomic oxygen binds more strongly than nitrogen, with the most stable [Formula: see text] structure exhibiting a binding energy of -2.47 eV, indicating chemisorption onto the surface. Surface reconstructions were observed for the most stable minima of both atomic species. Positive workfunction changes were calculated for both adsorbed oxygen and nitrogen if the adsorbate interacted with zinc atoms. Negative workfunction changes were calculated when the adsorbate interacted with both surface oxygen and zinc atoms. Interactions between the adsorbate and the surface zinc atoms resulted in ionic-type bonding, whereas interactions with oxygen atoms were more likely to result in the formation of covalent-type bonding. The positive workfunction changes correlate with an experimentally observed increase in resistance of ZnO conductometric sensor devices.

  1. Secondary Electron Yield on Cryogenic Surfaces as a Function of Physisorbed Gases

    CERN Document Server

    Kuzucan, A; Taborelli, M; Störi, H

    2011-01-01

    Electron cloud is a serious limitation for the operation of particle accelerators with intense positively charged beams. It occurs if the secondary electron yield (SEY) of the beam-pipe surface is sufficiently high to induce an electron multiplication. At low surface temperatures, the SEY is strongly influenced by the nature of the physisorbed gases and by the corresponding surface coverage. These conditions occur in many accelerators operating with superconducting magnets and cold vacuum sections such as the LHC and RHIC. In this work, we investigated the variation of the SEY of copper, aluminium and electro-polished copper as a function of physisorbed N2, CO, CO2, CH4, Kr, C2H6 at cryogenic temperatures. The conditioning by electron bombardment of the surface after the physisorption of H2O on electro polished copper will also be presented. The results of the various gases are compared in order to find a rationale for the behaviour of the secondary electrons for the various adsorbates.

  2. c-Met and Other Cell Surface Molecules: Interaction, Activation and Functional Consequences

    Directory of Open Access Journals (Sweden)

    Giuditta Viticchiè

    2015-01-01

    Full Text Available The c-Met receptor, also known as the HGF receptor, is one of the most studied tyrosine kinase receptors, yet its biological functions and activation mechanisms are still not fully understood. c-Met has been implicated in embryonic development and organogenesis, in tissue remodelling homeostasis and repair and in cancer metastasis. These functions are indicative of the many cellular processes in which the receptor plays a role, including cell motility, scattering, survival and proliferation. In the context of malignancy, sustained activation of c-Met leads to a signalling cascade involving a multitude of kinases that initiate an invasive and metastatic program. Many proteins can affect the activation of c-Met, including a variety of other cell surface and membrane-spanning molecules or receptors. Some cell surface molecules share structural homology with the c-Met extracellular domain and can activate c-Met via clustering through this domain (e.g., plexins, whereas other receptor tyrosine kinases can enhance c-Met activation and signalling through intracellular signalling cascades (e.g., EGFR. In this review, we provide an overview of c-Met interactions and crosstalk with partner molecules and the functional consequences of these interactions on c-Met activation and downstream signalling, c-Met intracellular localization/recycling and c-Met degradation.

  3. Cell treatment and surface functionalization using a miniature atmospheric pressure glow discharge plasma torch

    International Nuclear Information System (INIS)

    Yonson, S; Coulombe, S; Leveille, V; Leask, R L

    2006-01-01

    A miniature atmospheric pressure glow discharge plasma torch was used to detach cells from a polystyrene Petri dish. The detached cells were successfully transplanted to a second dish and a proliferation assay showed the transplanted cells continued to grow. Propidium iodide diffused into the cells, suggesting that the cell membrane had been permeabilized, yet the cells remained viable 24 h after treatment. In separate experiments, hydrophobic, bacteriological grade polystyrene Petri dishes were functionalized. The plasma treatment reduced the contact angle from 93 0 to 35 0 , and promoted cell adhesion. Two different torch nozzles, 500 μm and 150 μm in internal diameter, were used in the surface functionalization experiments. The width of the tracks functionalized by the torch, as visualized by cell adhesion, was approximately twice the inside diameter of the nozzle. These results indicate that the miniature plasma torch could be used in biological micropatterning, as it does not use chemicals like the present photolithographic techniques. Due to its small size and manouvrability, the torch also has the ability to pattern complex 3D surfaces

  4. Facile and green synthesis of core-shell structured magnetic chitosan submicrospheres and their surface functionalization.

    Science.gov (United States)

    Li, Yiya; Yuan, Dongying; Dong, Mingjie; Chai, Zhihua; Fu, Guoqi

    2013-09-17

    Submicrometer-sized magnetite colloid nanocrystal clusters (MCNCs) provide a new avenue for constructing uniformly sized and highly magnetic composite submicrospheres. Herein, a facile and eco-friendly method is described for the synthesis of Fe3O4@poly(acrylic acid) (PAA)/chitosan (CS) core-shell submicrospheres using MCNCs bearing carboxyl groups as the magnetic cores. It is based on the self-assembly of positively charged CS chains on the surface of the oppositely charged MCNCs dispersed in the aqueous solution containing acrylic acid (AA) and a cross-linker N,N'-methylenebis(acrylamide) (MBA), followed by radical induced cross-linking copolymerization of AA and MBA along the CS chains. The resulting polymer shell comprises a medium shell of cross-linked PAA/CS polyelectrolyte complexes and an outer shell of protonated CS chains. It was found that the shell thickness could be tuned by varying either the concentration of radical initiator or the molar ratio of AA to aminoglucoside units of CS. To the surface of thus obtained Fe3O4@PAA/CS particles, Au nanoparticles, a variety of functional groups such as fluorescein, carboxyl, quaternary ammonium, and aliphatic bromide, and even functional polymer chains were successfully introduced. Therefore, such Fe3O4@PAA/CS submicrospheres may be used as versatile magnetic functional scaffolds in biorelated areas like bioseparation and medical assay, considering the unique features of CS like nontoxicity and biocompatibility.

  5. Effect of wave-function localization on the time delay in photoemission from surfaces

    International Nuclear Information System (INIS)

    Zhang, C.-H.; Thumm, U.

    2011-01-01

    We investigate streaking time delays in the photoemission from a solid model surface as a function of the degree of localization of the initial-state wave functions. We consider a one-dimensional slab with lattice constant a latt of attractive Gaussian-shaped core potentials of width σ. The parameter σ/a latt thus controls the overlap between adjacent core potentials and localization of the electronic eigenfunctions on the lattice points. Small values of σ/a latt latt > or approx 0.4. By numerically solving the time-dependent Schroedinger equation, we calculate photoemission spectra from which we deduce a characteristic bimodal shape of the band-averaged photoemission time delay: as the slab eigenfunctions become increasingly delocalized, the time delay quickly decreases near σ/a latt =0.3 from relatively large values below σ/a latt ∼0.2 to much smaller delays above σ/a latt ∼0.4. This change in wave-function localization facilitates the interpretation of a recently measured apparent relative time delay between the photoemission from core and conduction-band levels of a tungsten surface.

  6. Surface functionalization of solid state ultra-high molecular weight polyethylene through chemical grafting

    Science.gov (United States)

    Sherazi, Tauqir A.; Rehman, Tayyiba; Naqvi, Syed Ali Raza; Shaikh, Ahson Jabbar; Shahzad, Sohail Anjum; Abbas, Ghazanfar; Raza, Rizwan; Waseem, Amir

    2015-12-01

    The surface of ultra-high molecular weight polyethylene (UHMWPE) powder was functionalized with styrene using chemical grafting technique. The grafting process was initiated through radical generation on base polymer matrix in the solid state by sodium thiosulfate, while peroxides formed at radical sites during this process were dissociated by ceric ammonium nitrate. Various factors were optimized and reasonably high level of monomer grafting was achieved, i.e., 15.6%. The effect of different acids as additive and divinyl benzene (DVB) as a cross-linking agent was also studied. Post-grafting sulfonation was conducted to introduce the ionic moieties to the grafted polymer. Ion-exchange capacity (IEC) was measured experimentally and is found to be 1.04 meq g-1, which is in close agreement with the theoretical IEC values. The chemical structure of grafted and functionalized polymer was characterized by attenuated total reflection infrared spectroscopy (ATR-FTIR) and thermal properties were investigated by thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC). Thermal analysis depicts that the presence of radicals on the polymer chain accelerates the thermal decomposition process. The results signify that the chemical grafting is an effective tool for substantial surface modification and subsequent functionalization of polyethylene.

  7. Modified polarimetric bidirectional reflectance distribution function with diffuse scattering: surface parameter estimation

    Science.gov (United States)

    Zhan, Hanyu; Voelz, David G.

    2016-12-01

    The polarimetric bidirectional reflectance distribution function (pBRDF) describes the relationships between incident and scattered Stokes parameters, but the familiar surface-only microfacet pBRDF cannot capture diffuse scattering contributions and depolarization phenomena. We propose a modified pBRDF model with a diffuse scattering component developed from the Kubelka-Munk and Le Hors et al. theories, and apply it in the development of a method to jointly estimate refractive index, slope variance, and diffuse scattering parameters from a series of Stokes parameter measurements of a surface. An application of the model and estimation approach to experimental data published by Priest and Meier shows improved correspondence with measurements of normalized Mueller matrix elements. By converting the Stokes/Mueller calculus formulation of the model to a degree of polarization (DOP) description, the estimation results of the parameters from measured DOP values are found to be consistent with a previous DOP model and results.

  8. Functional possibilities of organosilicon coatings on the surface of CsI-based scintillators

    CERN Document Server

    Andryustchenko, L A; Goriletsky, V I; Zaslavsky, B G; Zosim, D I; Charkina, T A; Trefilova, L N; Renker, D; Ritt, S; Mzhavia, D A

    2002-01-01

    It has been shown that a thin film (15+-5 mu m) based on organosilicon coating applied to all surface of CsI and CsI(Tl) scintillators excluding the output window, can combine the following functions: (1) covering from atmospheric effects; (2) scintillation light convertor of luminescence towards the region of higher spectral sensitivity of the photoreceiver and (3) ancillary surface for performance of operations on changing the light collection coefficient without the risk to exceed limited size tolerations. Wavelength-shifting coating effect on radiation hardness of pure CsI is discussed. After irradiation a new absorption bands appear in the range 250-300 nm mainly. So, contrary to the 310 nm emission, the energy losses for converted light remain the same.

  9. Pressure and surface tension of soild-liquid interface using Tarazona density functional theory

    Directory of Open Access Journals (Sweden)

    M. M.

    2000-12-01

    Full Text Available   The weighted density functional theory proposed by Tarazona is applied to study the solid-liquid interface. In the last two decades the weighted density functional became a useful tool to consider the properties of inhomogeneous liquids. In this theory, the role of the size of molecules or the particles of which the matter is composed, was found to be important. In this resarch we study a hard sphere fluid beside a hard wall. For this study the liquid is an inhomogeneous system. We use the definition of the direct correlation function as a second derivative of free energy with respect to the density. We use this definition and the definition of the weighting function, then we minimize the grand potential with respect to the density to get the Euler Lagrange equation and we obtain an integral equation to find the inhomogeneous density profile. The obtained density profile as a function of the distance from the wall, for different bulk density is plotted in three dimensions. We also calculate the pressure and compare it with the Carnahan-starling results, and finally we obtained the surface tension at liquid-solid interface and compared it with the results of Monte Carlo simulation.

  10. Impact of Smoking on the Ocular Surface, Tear Function, and Tear Osmolarity.

    Science.gov (United States)

    Aktaş, Serdar; Tetikoğlu, Mehmet; Koçak, Ahmet; Kocacan, Metin; Aktaş, Hatice; Sağdık, Hacı Murat; Özcura, Fatih

    2017-12-01

    This study evaluated the effects of cigarette smoking on the ocular surface, tear function, and tear osmolarity. A total of 50 smokers with at least 5 years of heavy smoking (defined as 1 pack/day) and 51 nonsmoking, healthy individuals were enrolled. Tear osmolarity was measured with an osmometer (TearLab ™ Osmolarity System). Ocular surface examinations involved corneal fluorescein staining, measurement of the tear film breakup time (TBUT), the Schirmer 1 test, measurement of corneal sensitivity with a Cochet-Bonnet esthesiometer, and conjunctival impression cytology. Dry eye symptoms were scored using the Ocular Surface Disease Index (OSDI) questionnaire. The results were compared with those from an age and sex-matched control group. The Chi-squared and independent sample t-tests were used for statistical analyses. The smokers had significantly higher tear osmolarity values (305.38 ± 9.81 vs. 301.14 ± 7.04 mOsm/L; p = 0.014) and OSDI scores (34.13 ± 16.58 vs. 18.09 ± 9.61; p < 0.001) than the healthy controls. However, the TBUT, corneal sensitivity, and goblet cell density were significantly lower in smokers compared to healthy controls, but the fluorescein staining and Schirmer 1 test results were not statistically different between the smokers and controls. Smoking results in increased osmolarity of the tear film, which can damage the ocular surface and tear function.

  11. Prevention of Synaptic Alterations and Neurotoxic Effects of PAMAM Dendrimers by Surface Functionalization

    Directory of Open Access Journals (Sweden)

    Felipe Vidal

    2017-12-01

    Full Text Available One of the most studied nanocarriers for drug delivery are polyamidoamine (PAMAM dendrimers. However, the alterations produced by PAMAM dendrimers in neuronal function have not been thoroughly investigated, and important aspects such as effects on synaptic transmission remain unexplored. We focused on the neuronal activity disruption induced by dendrimers and the possibility to prevent these effects by surface chemical modifications. Therefore, we studied the effects of fourth generation PAMAM with unmodified positively charged surface (G4 in hippocampal neurons, and compared the results with dendrimers functionalized in 25% of their surface groups with folate (PFO25 and polyethylene glycol (PPEG25. G4 dendrimers significantly reduced cell viability at 1 µM, which was attenuated by both chemical modifications, PPEG25 being the less cytotoxic. Patch clamp recordings demonstrated that G4 induced a 7.5-fold increment in capacitive currents as a measure of membrane permeability. Moreover, treatment with this dendrimer increased intracellular Ca2+ by 8-fold with a complete disruption of transients pattern, having as consequence that G4 treatment increased the synaptic vesicle release and frequency of synaptic events by 2.4- and 3-fold, respectively. PFO25 and PPEG25 treatments did not alter membrane permeability, total Ca2+ intake, synaptic vesicle release or synaptic activity frequency. These results demonstrate that cationic G4 dendrimers have neurotoxic effects and induce alterations in normal synaptic activity, which are generated by the augmentation of membrane permeability and a subsequent intracellular Ca2+ increase. Interestingly, these toxic effects and synaptic alterations are prevented by the modification of 25% of PAMAM surface with either folate or polyethylene glycol.

  12. Atomic and molecular adsorption on transition-metal carbide (111) surfaces from density-functional theory: a trend study of surface electronic factors

    DEFF Research Database (Denmark)

    Vojvodic, Aleksandra; Ruberto, C.; Lundqvist, Bengt

    2010-01-01

    This study explores atomic and molecular adsorption on a number of early transition-metal carbides (TMCs) in NaCl structure by means of density-functional theory calculations. The investigated substrates are the TM-terminated TMC(111) surfaces, of interest because of the presence of different types......, surface relaxations, Bader charges, and surface-localized densities of states (DOSs). Detailed comparisons between surface and bulk DOSs reveal the existence of transition-metal localized SRs (TMSRs) in the pseudogap and of several C-localized SRs (CSRs) in the upper valence band on all considered TMC(111......) surfaces. The spatial extent and the dangling bond nature of these SRs are supported by real-space analyses of the calculated Kohn-Sham wavefunctions. Then, atomic and molecular adsorption energies, geometries, and charge transfers are presented. An analysis of the adsorbate-induced changes in surface DOSs...

  13. Surface reactivity of Ge[111] for organic functionalization by means of a radical-initiated reaction: A DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Rubio-Pereda, Pamela, E-mail: rubio.pereda@gmail.com [Centro de Investigación Científica y de Educación Superior de Ensenada 3918, Código Postal 22860, Ensenada, Baja California (Mexico); Takeuchi, Noboru, E-mail: takeuchi@cnyn.unam.mx [Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Apartado Postal 14, Código Postal 22800, Ensenada, Baja California (Mexico)

    2016-08-30

    Highlights: • The surface reactivity of the Ge [111] surface is studied with DFT for the attachment of organic molecules by means of a radical-initiated reaction. • A hydrogen vacancy in the hydrogen terminated Ge [111] surface exhibits an accumulation of charge and electron pairing. • These characteristics make the hydrogen vacancy less reactive for the attachment of unsaturated organic molecules. • The adsorption of acetylene is probable to occur while the adsorption of ethylene and styrene is substantially less probable to occur. • The hydrogen terminated Ge [111] surface is found to be less reactive than its two-dimensional analogue, the hydrogen-terminated germanene. - Abstract: The study of interfacial chemistry at semiconductor surfaces has become an important area of research. Functionalities such as molecular recognition, biocompatibility of surfaces, and molecular computing, could be achieved by the combinations of organic chemistry with the semiconductor technology. One way to accomplish this goal is by means of organic functionalization of semiconductor surfaces such as the bulk-terminated germanium surfaces, more specifically the Ge[111]. In this work, we theoretically study, by applying density functional theory, the surface reactivity of the bulk-terminated Ge[111] surface for organic functionalization by means of a radical-initiated reaction of unsaturated molecules such as acetylene, ethylene and styrene with a hydrogen vacancy on a previously hydrogen-terminated Ge[111] surface. Results derived from this work are compared with those obtained in our previous calculations on the germanene surface, following the same chemical route. Our calculations show an accumulation of electronic charge at the H-vacancy having as a result electron pairing due to strong lattice-electron coupling and therefore a diminished surface reactivity. Calculation of the transition states for acetylene and ethylene indicates that the surface reactivity of the

  14. Surface reactivity of Ge[111] for organic functionalization by means of a radical-initiated reaction: A DFT study

    International Nuclear Information System (INIS)

    Rubio-Pereda, Pamela; Takeuchi, Noboru

    2016-01-01

    Highlights: • The surface reactivity of the Ge [111] surface is studied with DFT for the attachment of organic molecules by means of a radical-initiated reaction. • A hydrogen vacancy in the hydrogen terminated Ge [111] surface exhibits an accumulation of charge and electron pairing. • These characteristics make the hydrogen vacancy less reactive for the attachment of unsaturated organic molecules. • The adsorption of acetylene is probable to occur while the adsorption of ethylene and styrene is substantially less probable to occur. • The hydrogen terminated Ge [111] surface is found to be less reactive than its two-dimensional analogue, the hydrogen-terminated germanene. - Abstract: The study of interfacial chemistry at semiconductor surfaces has become an important area of research. Functionalities such as molecular recognition, biocompatibility of surfaces, and molecular computing, could be achieved by the combinations of organic chemistry with the semiconductor technology. One way to accomplish this goal is by means of organic functionalization of semiconductor surfaces such as the bulk-terminated germanium surfaces, more specifically the Ge[111]. In this work, we theoretically study, by applying density functional theory, the surface reactivity of the bulk-terminated Ge[111] surface for organic functionalization by means of a radical-initiated reaction of unsaturated molecules such as acetylene, ethylene and styrene with a hydrogen vacancy on a previously hydrogen-terminated Ge[111] surface. Results derived from this work are compared with those obtained in our previous calculations on the germanene surface, following the same chemical route. Our calculations show an accumulation of electronic charge at the H-vacancy having as a result electron pairing due to strong lattice-electron coupling and therefore a diminished surface reactivity. Calculation of the transition states for acetylene and ethylene indicates that the surface reactivity of the

  15. Electron propagator and surface Green's function calculations in transport molecular junctions

    Science.gov (United States)

    Kletsov, Aleksey

    A new theoretical approach to the calculation of electrical current through a molecular wire, based on ab initio electron propagator methodology, is proposed. The analytical expression for electric current is derived for an arbitrary number of terminal transport orbitals, which is given in terms of Dyson poles, Dyson pole strengths, overlap matrix elements, and expansion coefficients of atomic wavefunctions. The proposed approach is applied to calculations of the current-voltage characteristics of the transport molecular junction with a 1,4-benzene dithiol (BDT) molecule as a bridge. The obtained current-voltage characteristics exhibit negative differential resistance, that can be used in practical electronic devices. From the analysis of the output data, the origin of negative differential resistance in BDT molecular wire is explained. The observation of negative differential resistance in transport molecular devices based on a BDT molecule is predicted for certain Fermi energies. To discover the predicted effect, experimentalists should search for the appropriate Fermi energy by varying metal electrodes, coated by a gold monolayer. In addition, a novel computational method for non-recursive calculations of the surface Green's function matrices, using an infinite number of principal layers, is proposed. This method is employed to calculate the spectral function of the gold and aluminum surfaces. It is shown that the surface spectral function of the metal electrode dependence on applied voltage and this dependence can significantly change the electric current through a molecular wire. The new ab initio methods and computational results presented in this work allow for the prediction of novel devices with unusual properties that can be used in nanotechnology applications.

  16. Application of instrument transfer function to a fringe projection system for measuring rough surfaces

    Science.gov (United States)

    Zhang, Bin; Davies, Angela; Ziegert, John; Evans, Christopher

    2017-08-01

    When fringe projection profilometry is used for measuring rough/textured surfaces, the fidelity of the measurement is subject to the spatial frequency response. The instrument transfer function (ITF) is one appealing approach to characterize this property. The foundation of ITF analysis is based on the linear theory; only linear systems are appropriate for ITF analysis. A fringe projection system is intrinsically nonlinear, but it can be approximated as a linear system when certain conditions are met. Here we investigate the linear conditions of a custom fringe projection system designed for an additive manufacturing application. The applicability of ITF is discussed through mathematical analysis and simulations.

  17. Systems and methods for producing metal clusters; functionalized surfaces; and droplets including solvated metal ions

    Science.gov (United States)

    Cooks, Robert Graham; Li, Anyin; Luo, Qingjie

    2017-08-01

    The invention generally relates to systems and methods for producing metal clusters; functionalized surfaces; and droplets including solvated metal ions. In certain aspects, the invention provides methods that involve providing a metal and a solvent. The methods additionally involve applying voltage to the solvated metal to thereby produce solvent droplets including ions of the metal containing compound, and directing the solvent droplets including the metal ions to a target. In certain embodiments, once at the target, the metal ions can react directly or catalyze reactions.

  18. Recognition processes at a functionalized lipid surface observed with molecular resolution

    DEFF Research Database (Denmark)

    Vaknin, D.; Als-Nielsen, J.; Piepenstock, M.

    1991-01-01

    The specific binding of proteins to functionalized lipid monolayers on aqueous subphases was characterized by neutron reflectivity and fluorescence microscopy measurements. Due to the high affinity and high specificity of their noncovalent interaction, streptavidin (SA) and biotin (vitamin H) were...... with each protein molecule. Quantitative binding was found to occur at biotin surface concentrations as low as 1 molecule/1,250 angstrom 2 (compared with approximately 1 molecule/40 angstrom 2 for dense packing). This study demonstrates the application of a promising new tool for the systematic...

  19. Understanding charge transfer of Li+ and Na+ ions scattered from metal surfaces with high work function

    International Nuclear Information System (INIS)

    Chen Lin; Wu Wen-Bin; Liu Pin-Yang; Xiao Yun-Qing; Li Guo-Peng; Liu Yi-Ran; Jiang Hao-Yu; Guo Yan-Ling; Chen Xi-Meng

    2016-01-01

    For Li + and Na + ions scattered from high work function metal surfaces, efficient neutralization is observed, and it cannot be explained by the conventional free electron model. In order to explain these experimental data, we investigate the velocity-dependent neutral fraction with the modified Brako–Newns (BN) model. The calculated results are in agreement with the experimental data. We find that the parallel velocity effect plays an important role in neutralizing the Li + and Na + ions for large angle scattering. The nonmonotonic velocity behavior of neutral fraction is strongly related to the distance-dependent coupling strength between the atomic level and metal states. (paper)

  20. Genetic Diversity of African and Worldwide Strains of Ralstonia solanacearum as Determined by PCR-Restriction Fragment Length Polymorphism Analysis of the hrp Gene Region

    Science.gov (United States)

    Poussier, Stephane; Vandewalle, Peggy; Luisetti, Jacques

    1999-01-01

    The genetic diversity among a worldwide collection of 120 strains of Ralstonia solanacearum was assessed by restriction fragment length polymorphism (RFLP) analysis of amplified fragments from the hrp gene region. Five amplified fragments appeared to be specific to R. solanacearum. Fifteen different profiles were identified among the 120 bacterial strains, and a hierarchical cluster analysis distributed them into eight clusters. Each cluster included strains belonging to a single biovar, except for strains of biovars 3 and 4, which could not be separated. However, the biovar 1 strains showed rather extensive diversity since they were distributed into five clusters whereas the biovar 2 and the biovar 3 and 4 strains were gathered into one and two clusters, respectively. PCR-RFLP analysis of the hrp gene region confirmed the results of previous studies which split the species into an “Americanum” division including biovar 1 and 2 strains and an “Asiaticum” division including biovar 3 and 4 strains. However, the present study showed that most of the biovar 1 strains, originating from African countries (Reunion Island, Madagascar, Zimbabwe, and Angola) and being included in a separate cluster, belong to the “Asiaticum” rather than to the “Americanum” division. These African strains could thus have evolved separately from other biovar 1 strains originating from the Americas. PMID:10224018

  1. Photo-induced refractive index and topographical surface gratings in functionalized nanocarbon solid film

    Energy Technology Data Exchange (ETDEWEB)

    McGee, David J.; Ferrie, John; Plachy, Aljoscha [Department of Physics, The College of New Jersey, Ewing, New Jersey 08628 (United States); Joo, Yongho; Choi, Jonathan; Kanimozhi, Catherine; Gopalan, Padma, E-mail: pgopalan@cae.wisc.edu [Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

    2015-11-02

    We demonstrate that a single-walled carbon nanotube network noncovalently coupled with a pyrene-modified azo-benzene chromophore functions as a host matrix for a broad range of photo-orientation and photomechanical effects. The chromophore could be efficiently reoriented through repeated trans-cis-trans isomerization under linearly polarized 480 nm light, with Δn of 0.012 at 650 nm and fast characteristic rise-times of 0.12 s. Erasable phase diffraction gratings could also be written, with permanent surface relief gratings forming at sufficiently long irradiation times. In addition to demonstrating a mechanism for photo-manipulation of single-walled carbon nanotubes, these results show photo-orientation of chromophores in azo-functionalized single-walled carbon nanotube networks as a path towards the photosensitive tuning of the electrostatic environment of the nanotube.

  2. Photo-induced refractive index and topographical surface gratings in functionalized nanocarbon solid film

    International Nuclear Information System (INIS)

    McGee, David J.; Ferrie, John; Plachy, Aljoscha; Joo, Yongho; Choi, Jonathan; Kanimozhi, Catherine; Gopalan, Padma

    2015-01-01

    We demonstrate that a single-walled carbon nanotube network noncovalently coupled with a pyrene-modified azo-benzene chromophore functions as a host matrix for a broad range of photo-orientation and photomechanical effects. The chromophore could be efficiently reoriented through repeated trans-cis-trans isomerization under linearly polarized 480 nm light, with Δn of 0.012 at 650 nm and fast characteristic rise-times of 0.12 s. Erasable phase diffraction gratings could also be written, with permanent surface relief gratings forming at sufficiently long irradiation times. In addition to demonstrating a mechanism for photo-manipulation of single-walled carbon nanotubes, these results show photo-orientation of chromophores in azo-functionalized single-walled carbon nanotube networks as a path towards the photosensitive tuning of the electrostatic environment of the nanotube

  3. Photo-induced refractive index and topographical surface gratings in functionalized nanocarbon solid film

    Science.gov (United States)

    McGee, David J.; Ferrie, John; Plachy, Aljoscha; Joo, Yongho; Choi, Jonathan; Kanimozhi, Catherine; Gopalan, Padma

    2015-11-01

    We demonstrate that a single-walled carbon nanotube network noncovalently coupled with a pyrene-modified azo-benzene chromophore functions as a host matrix for a broad range of photo-orientation and photomechanical effects. The chromophore could be efficiently reoriented through repeated trans-cis-trans isomerization under linearly polarized 480 nm light, with Δn of 0.012 at 650 nm and fast characteristic rise-times of 0.12 s. Erasable phase diffraction gratings could also be written, with permanent surface relief gratings forming at sufficiently long irradiation times. In addition to demonstrating a mechanism for photo-manipulation of single-walled carbon nanotubes, these results show photo-orientation of chromophores in azo-functionalized single-walled carbon nanotube networks as a path towards the photosensitive tuning of the electrostatic environment of the nanotube.

  4. Silica encapsulation of fluorescent nanodiamonds for colloidal stability and facile surface functionalization.

    Science.gov (United States)

    Bumb, Ambika; Sarkar, Susanta K; Billington, Neil; Brechbiel, Martin W; Neuman, Keir C

    2013-05-29

    Fluorescent nanodiamonds (FNDs) emit in the near-IR and do not photobleach or photoblink. These properties make FNDs better suited for numerous imaging applications compared with commonly used fluorescence agents such as organic dyes and quantum dots. However, nanodiamonds do not form stable suspensions in aqueous buffer, are prone to aggregation, and are difficult to functionalize. Here we present a method for encapsulating nanodiamonds with silica using an innovative liposome-based encapsulation process that renders the particle surface biocompatible, stable, and readily functionalized through routine linking chemistries. Furthermore, the method selects for a desired particle size and produces a monodisperse agent. We attached biotin to the silica-coated FNDs and tracked the three-dimensional motion of a biotinylated FND tethered by a single DNA molecule with high spatial and temporal resolution.

  5. Micropatterning of Functional Conductive Polymers with Multiple Surface Chemistries in Register

    DEFF Research Database (Denmark)

    Lind, Johan Ulrik; Acikgöz, Canet; Daugaard, Anders Egede

    2012-01-01

    A versatile procedure is presented for fast and efficient micropatterning of multiple types of covalently bound surface chemistry in perfect register on and between conductive polymer microcircuits. The micropatterning principle is applied to several types of native and functionalized PEDOT (poly(3......,4-ethylenedioxythiophene)) thin films. The method is based on contacting PEDOT-type thin films with a micropatterned agarose stamp containing an oxidant (aqueous hypochlorite) and applying a nonionic detergent. Where contacted, PEDOT not only loses its conductance but is entirely removed, thereby locally revealing...... of the method is illustrated by micropatterning cell-binding RGD-functionalized PEDOT on low cell-binding PMOXA (poly(2-methyl-2-oxazoline)) to produce cell-capturing microelectrodes on a cell nonadhesive background in a few simple steps. The method should be applicable to a wide range of native and chemically...

  6. Conventional and acoustic surface plasmons on noble metal surfaces: a time-dependent density functional theory study

    DEFF Research Database (Denmark)

    Yan, Jun; Jacobsen, Karsten W.; Thygesen, Kristian S.

    2012-01-01

    First-principles calculations of the conventional and acoustic surface plasmons (CSPs and ASPs) on the (111) surfaces of Cu, Ag, and Au are presented. The effect of s-d interband transitions on both types of plasmons is investigated by comparing results from the local density approximation...

  7. Controls on plant functional surface cover types along a precipitation gradient in the Negev Desert of Israel

    NARCIS (Netherlands)

    Buis, E.; Veldkamp, A.; Boeken, B.; Breemen, van N.

    2009-01-01

    We studied the controls on functional surface cover types in four catchments along a semi-arid to arid precipitation gradient in the northern Negev Desert of Israel. First, we selected four functional types, based on their unique water use and redistribution functionality: shrubs, Asphodelus

  8. Chemical Recycling of Expanded Polystyrene Waste: Synthesis of Novel Functional Polystyrene-Hydrazone Surface for Phenol Removal

    Directory of Open Access Journals (Sweden)

    Ali N. Siyal

    2013-01-01

    Full Text Available Expanded polystyrene (EPS waste was chemically recycled to a novel functional polystyrene-hydrazone (PSH surface by acetylation of polystyrene (PS and then condensation with phenyl hydrazine. The synthesized surface was characterized by the FT-IR and elemental analysis. Synthesized novel functional PSH surface was successfully applied for the treatment of phenol-contaminated industrial wastewater by solid-phase extraction. Multivariant sorption optimization was achieved by factorial design approach. 99.93% of phenol was removed from aqueous solution. FT-IR study showed the involvement of nitrogen of hydrazone moiety of synthesized surface for the uptake of phenol through the hydrogen bonding.

  9. Soil surface protection by Biocrusts: effects of functional groups on textural properties

    Science.gov (United States)

    Concostrina-Zubiri, Laura; Huber-Sannwald, Elisabeth; Martínez, Isabel; Flores Flores, José Luis; Escudero, Adrián

    2015-04-01

    In drylands, where vegetation cover is commonly scarce, soil surface is prone to wind and water soil erosion, with the subsequent loss of topsoil structure and chemical properties. These processes are even more pronounced in ecosystems subjected to extra erosive forces, such as grasslands and rangelands that support livestock production. However, some of the physiological and functional traits of biocrusts (i.e., complex association of cyanobacteria, lichens, mosses, fungi and soil particles) make them ideal to resist in disturbed environments and at the same time to protect soil surface from mechanical perturbations. In particular, the filaments and exudates of soil cyanobacteria and the rhizines of lichen can bind together soil particles, forming soil aggregates at the soil surface and thus enhancing soil stability. Also, they act as "biological covers" that preserve the most vulnerable soil layer from wind and runoff erosion and raindrop impact, maintaining soil structure and composition. In this work, we evaluated soil textural properties and organic matter content under different functional groups of biocrusts (i.e., cyanobacteria crust, 3 lichen species, 1 moss species) and in bare soil. In order to assess the impact of livestock trampling on soil properties and on Biocrust function, we sampled three sites conforming a disturbance gradient (low, medium and high impact sites) and a long-term livestock exclusion as control site. We found that the presence of biocrusts had little effects on soil textural properties and organic matter content in the control site, while noticeable differences were found between bare soil and soil under biocrusts (e.g., up to 16-37% higher clay content, compared to bare soil and up to 10% higher organic matter content). In addition, we found that depending on morphological traits and grazing regime, the effects of biocrusts changed along the gradient. For example, soil under the lichen Diploschistes diacapsis, with thick thallus

  10. Computational studies at the density functional theory (DFT) level about the surface functionalization of hexagonal monolayers by chitosan monomer

    Science.gov (United States)

    Ebrahimi, Javad; Ahangari, Morteza Ghorbanzadeh; Jahanshahi, Mohsen

    2018-05-01

    Theoretical investigations based on density functional theory have been carried out to understand the underlying interactions between the chitosan monomer and several types of hexagonal monolayers consisting of pristine and defected graphene and boron-nitride nanosheets. Based on the obtained results, it was found that the type of the interaction for all the systems is of non-covalent nature and the chitosan monomer physically interacts with the surface of mentioned nanostructures. The interaction strength was evaluated by calculating the adsorption energies for the considered systems and it was found that the adsorption of chitosan monomer accompanies by the release of about -0.67 and -0.66 eV energy for pristine graphene and h-BN monolayer, respectively. The role of structural defect has also been considered by embedding a Stone-Wales defect within the structure of mentioned monolayers and it was found that the introduced defect enhances the interactions between the chitosan monomer and nanostructures. The role of dispersion interactions has also been taken into account and it was found that these long-range interactions play the dominating role in the attachment of chitosan monomer onto the graphene sheet, while having strong contribution together with the electrostatic interactions for the stabilization of chitosan onto the surface of h-BN monolayer. For all the cases, the adsorption of chitosan monomer did not change the inherent electronic properties of the nanostructures based on the results of charge transfer analysis and energy gap calculations. The findings of the present work would be very useful in future investigations to explore the potential applications of these hybrid materials in materials science and bio-related fields.

  11. Surface EMG to assess arm function in boys with DMD: a pilot study.

    Science.gov (United States)

    Janssen, Mariska M H P; Harlaar, Jaap; de Groot, Imelda J M

    2015-04-01

    Preserving functional abilities of the upper extremities is a major concern in boys with Duchenne Muscular Dystrophy (DMD). To assess disease progression and treatments, good knowledge on arm function in boys with DMD is essential. Therefore, feasibility and validity of the use of surface electromyography (sEMG) to assess arm function in boys with DMD was examined. Five boys with DMD and 6 age-matched controls participated in this study. Single joint movements and ADL activities were examined while recording sEMG of main shoulder and elbow muscles. All boys with DMD and controls were able to perform the non standardized movements of the measurement protocol, however one boy with DMD was not able to perform all the standardized movements. Boys with DMD used significantly more of their maximal muscle capacity for all muscles to conduct movements compared to controls. The measurement protocol was feasible to assess arm function in boys with DMD. This tool was able to discriminate between DMD patients and controls. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Surface Functionalization of Iron Oxide Nanoparticles with Gallic Acid as Potential Antioxidant and Antimicrobial Agents

    Directory of Open Access Journals (Sweden)

    Syed Tawab Shah

    2017-10-01

    Full Text Available In this research, we report the size-controlled synthesis and surface-functionalization of magnetite with the natural antioxidant gallic acid (GA as a ligand, using in situ and post-synthesis methods. GA functionalization provided narrow size distribution, with an average particle size of 5 and 8 nm for in situ synthesis of gallic acid functionalized magnetite IONP@GA1 and IONP@GA2, respectively, which are ultra-small particles as compared to unfunctionalized magnetite (IONP and post functionalized magnetite IONP@GA3 with average size of 10 and 11 nm respectively. All the IONPs@GA samples were found hydrophilic with stable aggregation state. Prior to commencement of experimental lab work, PASS software was used to predict the biological activities of GA and it is found that experimental antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH assay and antimicrobial studies using well diffusion method are in good agreement with the simulated results. Furthermore, the half maximal inhibitory concentration (IC50 values of DPPH antioxidant assay revealed a 2–4 fold decrease as compared to unfunctionalized IONP. In addition to antioxidant activity, all the three IONP@GA proved outstanding antimicrobial activity while testing on different bacterial and fungal strains. The results collectively indicate the successful fabrication of novel antioxidant, antimicrobial IONP@GA composite, which are magnetically separable, efficient, and low cost, with potential applications in polymers, cosmetics, and biomedical and food industries.

  13. Surface Functionalization of Iron Oxide Nanoparticles with Gallic Acid as Potential Antioxidant and Antimicrobial Agents

    Science.gov (United States)

    Shah, Syed Tawab; Saad, Omar; Simarani, Khanom; Chowdhury, Zaira Zaman; Alhadi, Abeer A.; Al-Ani, Lina A.

    2017-01-01

    In this research, we report the size-controlled synthesis and surface-functionalization of magnetite with the natural antioxidant gallic acid (GA) as a ligand, using in situ and post-synthesis methods. GA functionalization provided narrow size distribution, with an average particle size of 5 and 8 nm for in situ synthesis of gallic acid functionalized magnetite IONP@GA1 and IONP@GA2, respectively, which are ultra-small particles as compared to unfunctionalized magnetite (IONP) and post functionalized magnetite IONP@GA3 with average size of 10 and 11 nm respectively. All the IONPs@GA samples were found hydrophilic with stable aggregation state. Prior to commencement of experimental lab work, PASS software was used to predict the biological activities of GA and it is found that experimental antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and antimicrobial studies using well diffusion method are in good agreement with the simulated results. Furthermore, the half maximal inhibitory concentration (IC50) values of DPPH antioxidant assay revealed a 2–4 fold decrease as compared to unfunctionalized IONP. In addition to antioxidant activity, all the three IONP@GA proved outstanding antimicrobial activity while testing on different bacterial and fungal strains. The results collectively indicate the successful fabrication of novel antioxidant, antimicrobial IONP@GA composite, which are magnetically separable, efficient, and low cost, with potential applications in polymers, cosmetics, and biomedical and food industries. PMID:28981476

  14. Density functionals for surface science: Exchange-correlation model development with Bayesian error estimation

    DEFF Research Database (Denmark)

    Wellendorff, Jess; Lundgård, Keld Troen; Møgelhøj, Andreas

    2012-01-01

    A methodology for semiempirical density functional optimization, using regularization and cross-validation methods from machine learning, is developed. We demonstrate that such methods enable well-behaved exchange-correlation approximations in very flexible model spaces, thus avoiding the overfit......A methodology for semiempirical density functional optimization, using regularization and cross-validation methods from machine learning, is developed. We demonstrate that such methods enable well-behaved exchange-correlation approximations in very flexible model spaces, thus avoiding...... the energetics of intramolecular and intermolecular, bulk solid, and surface chemical bonding, and the developed optimization method explicitly handles making the compromise based on the directions in model space favored by different materials properties. The approach is applied to designing the Bayesian error...... estimation functional with van der Waals correlation (BEEF-vdW), a semilocal approximation with an additional nonlocal correlation term. Furthermore, an ensemble of functionals around BEEF-vdW comes out naturally, offering an estimate of the computational error. An extensive assessment on a range of data...

  15. Electrochemical surface functionalization of carbon fibers for chemical affinity improvement with epoxy resins

    Science.gov (United States)

    Kainourgios, Panayiotis; Kartsonakis, Ioannis A.; Dragatogiannis, Dimitrios A.; Koumoulos, Elias P.; Goulis, Panagiotis; Charitidis, Costas A.

    2017-09-01

    The purpose of this study is to increase the wetting properties of carbon fibers in order to improve the adhesion force between the fiber and the polymer matrix. Commercial carbon fibers were surface functionalized through cyclic voltammetry together with potentiostatic conditions in aqueous electrolyte solutions of H2SO4, in the presence of acrylic acid, methacrylic acid, acrylonitrile and N-vinylpyrrolidone monomers. The anodic and cathodic peaks were correlated with oxide formation and their partial reduction, respectively. The produced surface modified carbon fibers were wetted with epoxy resin so that to produce dumbbell type composites for tensile strength testing. The nature of oxygen containing groups on the fibers surface was determined by Fourier-transform infrared and Raman spectroscopy. Moreover, the wetting properties of the treated carbon fibers were evaluated via contact angle measurements whereas the morphology of the coated fibers was investigated via scanning electron microscopy. Finally, the mechanical performance of the composites was evaluated by means of tensile testing and strength measurements.

  16. Surface modification by cold-plasma technique for dental implants—Bio-functionalization with binding pharmaceuticals

    Directory of Open Access Journals (Sweden)

    Masao Yoshinari

    2011-08-01

    At the bone tissue/implant interface, a thin calcium phosphate coating and rapid heating with infrared radiation were effective in controlling the dissolution without cracking the coating. These thin calcium phosphate coatings may directly promote osteogenisis, but also enable immobilization and subsequent drug delivery system (DDS of bisphosphonates. Simvastatin is also an effective candidate that is reported to increase the expression of BMP-2. The thin-film of hexamethyldisiloxane (HMDSO was plasma-polymerized onto titanium, and then HMDSO surface was activated by O2-plasma treatment. A quartz crystal microbalance (QCM-D technique demonstrated that simvastatin was immobilized on the plasma-treated surfaces due to introduction of O2-functional groups. At the soft tissue/implant interface, multi-grooved surface topographies and utilizing the adhesive proteins such as fibronectin or laminin-5 may help in providing a biological seal around the implant. At the oral fluid/implant interface, an alumina coating, F+-implantation and immobilization of anti-microbial peptides were responsible for inhibiting the biofilm accumulation.

  17. On-chip surface modified nanostructured ZnO as functional pH sensors

    Science.gov (United States)

    Zhang, Qing; Liu, Wenpeng; Sun, Chongling; Zhang, Hao; Pang, Wei; Zhang, Daihua; Duan, Xuexin

    2015-09-01

    Zinc oxide (ZnO) nanostructures are promising candidates as electronic components for biological and chemical applications. In this study, ZnO ultra-fine nanowire (NW) and nanoflake (NF) hybrid structures have been prepared by Au-assisted chemical vapor deposition (CVD) under ambient pressure. Their surface morphology, lattice structures, and crystal orientation were investigated by scanning electron microscopy (SEM), x-ray diffraction (XRD), and transmission electron microscopy (TEM). Two types of ZnO nanostructures were successfully integrated as gate electrodes in extended-gate field-effect transistors (EGFETs). Due to the amphoteric properties of ZnO, such devices function as pH sensors. We found that the ultra-fine NWs, which were more than 50 μm in length and less than 100 nm in diameter, performed better in the pH sensing process than NW-NF hybrid structures because of their higher surface-to-volume ratio, considering the Nernst equation and the Gouy-Chapman-Stern model. Furthermore, the surface coating of (3-Aminopropyl)triethoxysilane (APTES) protects ZnO nanostructures in both acidic and alkaline environments, thus enhancing the device stability and extending its pH sensing dynamic range.

  18. Influence of surface functional groups on lithium ion intercalation of carbon cloth

    International Nuclear Information System (INIS)

    Ventosa, Edgar; Xia, Wei; Klink, Stefan; La Mantia, Fabio; Muhler, Martin; Schuhmann, Wolfgang

    2012-01-01

    Commercial carbon cloth made of PAN-based carbon fibres was used as free-standing anode for lithium intercalation. The role of surface functional groups on the specific irreversible charge loss and reversible charge during the intercalation and de-intercalation of lithium ions into carbon cloth has been investigated. Oxygen groups have been introduced by nitric acid vapour treatment and subsequently gradually removed by thermal treatment at different temperatures in He or H 2 atmosphere as confirmed by X-ray photoelectron spectroscopy. A clear correlation between the amount of surface-bound oxygen groups and the irreversible specific charge was observed. Three irreversible processes were distinguished during the first cathodic scan: (i) reduction of oxygen groups, (ii) formation of the solid electrolyte interphase (SEI) and (iii) presumably exfoliation. The latter one was only observed for samples with low surface oxygen concentration, and its contribution to the irreversible capacity was small due to the low graphitization degree of the samples. An increased specific reversible charge upon increasing the amount of oxygen-containing groups was observed with the main improvement above 1.5 V.

  19. Dynamic stability of functionally graded nanobeam based on nonlocal Timoshenko theory considering surface effects

    Science.gov (United States)

    Saffari, Shahab; Hashemian, Mohammad; Toghraie, Davood

    2017-09-01

    Based on nonlocal Timoshenko beam theory, dynamic stability of functionally graded (FG) nanobeam under axial and thermal loading was investigated. Surface stress effects were implemented according to Gurtin-Murdoch continuum theory. Using power law distribution for FGM and von Karman geometric nonlinearity, governing equations were derived based on Hamilton's principle. The developed nonlocal models have the capability of interpreting small scale effects. Pasternak elastic medium was employed to represent the interaction of the FG nanobeam and the surrounding elastic medium. A parametric study was conducted to focus influences of the static load factor, temperature change, gradient index, nonlocal parameter, slenderness ratio, surface effect and springs constants of the elastic medium on the dynamic instability region (DIR) of the FG beam with simply-supported boundary conditions. It was found that differences between DIRs predicted by local and nonlocal beam theories are significant for beams with lower aspect ratio. Moreover, it was observed that in contrast to high temperature