Science.gov

Sample records for cellular surface characteristics

  1. Impact of cranberry on Escherichia coli cellular surface characteristics

    SciTech Connect

    Johnson, Brandy J.; Malanoski, Anthony P.; Ligler, Frances S.

    2008-12-19

    The anti-adhesive effects of cranberry have been attributed to both interactions of its components with the surface of bacterial cells and to inhibition of p-fimbriae expression. Previous reports also suggested that the presence of cranberry juice changed the Gram stain characteristics of Escherichia coli. Here, we show that the morphology of E. coli is changed when grown in the presence of juice or extract from Vaccinium macrocarpon (cranberry). Gene expression analysis indicates the down regulation of flagellar basal body rod and motor proteins. Consistent with this finding and previous reports, the SEM images indicate a decrease in the visible p-fimbriae. The iodine used in Gram-staining protocols was found to interact differently with the bacterial membrane when cells were cultured in spiked media. Slight alterations in the Gram stain protocol demonstrated that culturing in the presence of cranberry juice does not change the Gram stain characteristics contradicting other reports.

  2. Cellular responses evoked by different surface characteristics of intraosseous titanium implants.

    PubMed

    Feller, Liviu; Jadwat, Yusuf; Khammissa, Razia A G; Meyerov, Robin; Schechter, Israel; Lemmer, Johan

    2015-01-01

    The properties of biomaterials, including their surface microstructural topography and their surface chemistry or surface energy/wettability, affect cellular responses such as cell adhesion, proliferation, and migration. The nanotopography of moderately rough implant surfaces enhances the production of biological mediators in the peri-implant microenvironment with consequent recruitment of differentiating osteogenic cells to the implant surface and stimulates osteogenic maturation. Implant surfaces with moderately rough topography and with high surface energy promote osteogenesis, increase the ratio of bone-to-implant contact, and increase the bonding strength of the bone to the implant at the interface. Certain features of implant surface chemistry are also important in enhancing peri-implant bone wound healing. It is the purpose of this paper to review some of the more important features of titanium implant surfaces which have an impact on osseointegration.

  3. Ti-O-N/Ti composite coating on Ti-6Al-4V: surface characteristics, corrosion properties and cellular responses.

    PubMed

    Cao, Xiao-Lin; Sun, Tao; Yu, Yonghao

    2015-03-01

    To enhance the corrosion resistance of Ti-6Al-4V and extend its lifetime in medical applications, Ti-O-N/Ti composite coating was synthesized on the surface via plasma immersion ion implantation and deposition (PIIID). Surface morphology and cross sectional morphology of the composite coating were characterized using atomic force microscopy and scanning electron microscopy, respectively. Although X-ray photoelectron spectroscopic analysis revealed that the Ti-O-N/Ti composite coating was composed of non-stoichiometric titanium oxide, titanium nitride and titanium oxynitride, no obvious characteristic peak corresponding to the crystalline phases of them was detected in the X-ray diffraction pattern. In accordance with Owens-Wendt equation, surface free energy of the uncoated and coated samples was calculated and compared. Moreover, the corrosion behavior of uncoated and coated samples was evaluated by means of electrochemical impedance spectroscopy measurement, and an equivalent circuit deriving from Randles model was used to fit Bode plots and describe the electrochemical processes occurring at the sample/electrolyte interface. On the basis of the equivalent circuit model, the resistance of the composite coating was 4.7 times higher than that of the passive layer on uncoated samples, indicating the enhanced corrosion resistance after PIIID treatment. Compared to uncoated Ti-6Al-V, Ti-O-N/Ti-coated samples facilitated ostoblast proliferation within 7 days of cell culture, while there was no statistically significant difference in alkaline phosphate activity between uncoated and coated samples during 21 days of cell culture.

  4. Surface characteristics of thermally treated titanium surfaces

    PubMed Central

    Lee, Yang-Jin; Cui, De-Zhe; Jeon, Ha-Ra; Chung, Hyun-Ju; Park, Yeong-Joon; Kim, Ok-Su

    2012-01-01

    Purpose The characteristics of oxidized titanium (Ti) surfaces varied according to treatment conditions such as duration time and temperature. Thermal oxidation can change Ti surface characteristics, which affect many cellular responses such as cell adhesion, proliferation, and differentiation. Thus, this study was conducted to evaluate the surface characteristics and cell response of thermally treated Ti surfaces. Methods The samples were divided into 4 groups. Control: machined smooth titanium (Ti-S) was untreated. Group I: Ti-S was treated in a furnace at 300℃ for 30 minutes. Group II: Ti-S was treated at 500℃ for 30 minutes. Group III: Ti-S was treated at 750℃ for 30 minutes. A scanning electron microscope, atomic force microscope, and X-ray diffraction were used to assess surface characteristics and chemical composition. The water contact angle and surface energy were measured to assess physical properties. Results The titanium dioxide (TiO2) thickness increased as the treatment temperature increased. Additional peaks belonging to rutile TiO2 were only found in group III. The contact angle in group III was significantly lower than any of the other groups. The surface energy significantly increased as the treatment temperature increased, especially in group III. In the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, after 24 hours of incubation, the assessment of cell viability showed that the optical density of the control had a higher tendency than any other group, but there was no significant difference. However, the alkaline phosphatase activity increased as the temperature increased, especially in group III. Conclusions Consequently, the surface characteristics and biocompatibility increased as the temperature increased. This indicates that surface modification by thermal treatment could be another useful method for medical and dental implants. PMID:22803009

  5. Sound attenuation characteristics of cellular metamaterials

    NASA Astrophysics Data System (ADS)

    Varanasi, Satya Surya Srinivas

    could be mitigated by the addition of appropriate treatments such as a lightweight grid that modified the incident sound field to be normally directed. Although the performance of the metamaterial-based barrier solutions was better compared to the conventional ones, the performance can be poor at the system eigenfrequencies. The possibility of shifting energy from the deficit bands to other regions where the barriers are more efficient was numerically explored for embodiments of segmented cellular materials having non-linear stiffness characteristics. The acoustical behavior of such materials was probed through representative two-dimensional models of a segmented plate with a contact interface. Super-harmonic response peaks were observed for pure harmonic excitations, the strength of which were found to strongly depend on the degree of non-linearity or bilinear stiffness ratio. The closer an excitation frequency was to the characteristic eigenfrequencies of the structure, the stronger was the super-harmonic response, which supported the idea of transferring energy from problematic frequency bands to higher frequencies. Finally, the possibility of a spatial-shift of energy from longitudinal to lateral direction was explored with the idea of eliminating the design constraints associated with conventional absorbing materials, and with the hope of realizing a compact sound absorber. The embodiment was a two-phase chiral composite made using a Topologically Interlocked Material (TIM) with its unit cell being a tetrahedron consisting of two helicoid dissections. A comparative study was conducted with standard microstructures inspired by the Voigt and Reuss models. The twist mode of the chiral composites was found to be excited by an incident sound field normal to the plane of the TIM assembly. Although this behavior is not unique to a chiral microstructure, many other microstructures do not exhibit this behavior. The excitation of the twist mode by the incident sound field

  6. Sialidases as regulators of bioengineered cellular surfaces.

    PubMed

    Zamora, Cristina Y; Ryan, Matthew J; d'Alarcao, Marc; Kumar, Krishna

    2015-07-01

    Human sialidases (NEUs) catalyze the removal of N-acetyl neuraminic acids from the glycome of the cell and regulate a diverse repertoire of nominal cellular functions, such as cell signaling and adhesion. A greater understanding of their substrate permissivity is of interest in order to discern their physiological functions in disease states and in the design of specific and effective small molecule inhibitors. Towards this, we have synthesized soluble fluorogenic reporters of mammalian sialidase activity bearing unnatural sialic acids commonly incorporated into the cellular glycocalyx via metabolic glycoengineering. We found cell-surface sialidases in Jurkat capable of cleaving unnatural sialic acids with differential activities toward a variety of R groups on neuraminic acid. In addition, we observed modulated structure-activity relationships when cell-surface sialidases were presented glycans with unnatural bulky, hydrophobic or fluorinated moieties incorporated directly via glycoengineering. Our results confirm the importance of cell-surface sialidases in glycoengineering incorporation data. We demonstrate the flexibility of human NEUs toward derivatized sugars and highlight the importance of native glycan presentation to sialidase binding and activity. These results stand to inform not only metabolic glycoengineering efforts but also inhibitor design.

  7. Sialidases as regulators of bioengineered cellular surfaces

    PubMed Central

    Zamora, Cristina Y; Ryan, Matthew J; d'Alarcao, Marc; Kumar, Krishna

    2015-01-01

    Human sialidases (NEUs) catalyze the removal of N-acetyl neuraminic acids from the glycome of the cell and regulate a diverse repertoire of nominal cellular functions, such as cell signaling and adhesion. A greater understanding of their substrate permissivity is of interest in order to discern their physiological functions in disease states and in the design of specific and effective small molecule inhibitors. Towards this, we have synthesized soluble fluorogenic reporters of mammalian sialidase activity bearing unnatural sialic acids commonly incorporated into the cellular glycocalyx via metabolic glycoengineering. We found cell-surface sialidases in Jurkat capable of cleaving unnatural sialic acids with differential activities toward a variety of R groups on neuraminic acid. In addition, we observed modulated structure–activity relationships when cell-surface sialidases were presented glycans with unnatural bulky, hydrophobic or fluorinated moieties incorporated directly via glycoengineering. Our results confirm the importance of cell-surface sialidases in glycoengineering incorporation data. We demonstrate the flexibility of human NEUs toward derivatized sugars and highlight the importance of native glycan presentation to sialidase binding and activity. These results stand to inform not only metabolic glycoengineering efforts but also inhibitor design. PMID:25795684

  8. Characteristics of cellular composition of periodontal pockets

    PubMed Central

    Hasiuk, Petro; Hasiuk, Nataliya; Kindiy, Dmytro; Ivanchyshyn, Victoriya; Kalashnikov, Dmytro; Zubchenko, Sergiy

    2016-01-01

    Purpose The development of inflammatory periodontal disease in young people is an urgent problem of today's periodontology, and requires a development of new methods that would give an opportunity not only to diagnose but also for prognosis of periodontitis course in a given patients contingent. Results Cellular structure of periodontal pockets is presented by hematogenous and epithelial cells. Our results are confirmed by previous studies, and show that the penetration of periodontal pathogens leads to formation in periodontal tissue of a highly active complex compounds—cytokines that are able to modify the activity of neutrophils and reduce their specific antibacterial properties. Cytokines not only adversely affect the periodontal tissues, but also cause further activation of cells that synthesized them, and inhibit tissue repair and process of resynthesis of connective tissue by fibroblasts. Conclusion Neutrophilic granulocytes present in each of the types of smear types, but their functional status and quantitative composition is different. The results of our cytological study confirmed the results of immunohistochemical studies, and show that in generalized periodontitis, an inflammatory cellular elements with disorganized epithelial cells and connective tissue of the gums and periodontium, and bacteria form specific types of infiltration in periodontal tissues. PMID:28180007

  9. Cellular Stress Response to Engineered Nanoparticles: Effect of Size, Surface Coating, and Cellular Uptake

    EPA Science Inventory

    CELLULAR STRESS RESPONSE TO ENGINEERED NANOPARTICLES: EFFECT OF SIZE, SURFACE COATING, AND CELLULAR UPTAKE RY Prasad 1, JK McGee2, MG Killius1 D Ackerman2, CF Blackman2 DM DeMarini2 , SO Simmons2 1 Student Services Contractor, US EPA, RTP, NC 2 US EPA, RTP, NC The num...

  10. Parameters and characteristics governing cellular internalization and trans-barrier trafficking of nanostructures

    PubMed Central

    Murugan, Karmani; Choonara, Yahya E; Kumar, Pradeep; Bijukumar, Divya; du Toit, Lisa C; Pillay, Viness

    2015-01-01

    Cellular internalization and trans-barrier transport of nanoparticles can be manipulated on the basis of the physicochemical and mechanical characteristics of nanoparticles. Research has shown that these factors significantly influence the uptake of nanoparticles. Dictating these characteristics allows for the control of the rate and extent of cellular uptake, as well as delivering the drug-loaded nanosystem intra-cellularly, which is imperative for drugs that require a specific cellular level to exert their effects. Additionally, physicochemical characteristics of the nanoparticles should be optimal for the nanosystem to bypass the natural restricting phenomena of the body and act therapeutically at the targeted site. The factors at the focal point of emerging smart nanomedicines include nanoparticle size, surface charge, shape, hydrophobicity, surface chemistry, and even protein and ligand conjugates. Hence, this review discusses the mechanism of internalization of nanoparticles and ideal nanoparticle characteristics that allow them to evade the biological barriers in order to achieve optimal cellular uptake in different organ systems. Identifying these parameters assists with the progression of nanomedicine as an outstanding vector of pharmaceuticals. PMID:25834433

  11. Spectral Characteristics of Titan's Surface

    NASA Astrophysics Data System (ADS)

    Griffith, Caitlin A.; Turner, Jake D.; Penteado, Paulo; Khamsi, Tymon B.; Soderblom, Jason M.

    2014-11-01

    Cassini/Huygens and ground-based measurements of Titan reveal an eroded surface, with lakes, dunes, and sinuous washes. These features, coupled with measurements of clouds and rain, indicate the transfer of methane between Titan’s surface and atmosphere. The presence of methane-damp lowlands suggests further that the atmospheric methane (which is continually depleted through photolysis) may be supplied by sub-surface reservoirs. The byproducts of methane photolysis condense onto the surface, leaving layers of organic sediments that record Titan’s past atmospheres.Thus knowledge of the source and history of Titan's atmosphere requires measurements of the large scale compositional makeup of Titan's surface, which is shrouded by a thick and hazy atmosphere. Towards this goal, we analyzed roughly 100,000 spectra recorded by Cassini’s Visual and Infrared Mapping Spectrometer (VIMS). Our study is confined to the latitude region (20S—20N) surrounding the landing site of the Huygens probe (at 10S, 192W), which supplied only measurement of the vertical profiles of the methane abundance and haze scattering characteristics. VIMS near-IR spectral images indicate subtle latitudinal and temporal variations in the haze characteristics in the tropics. We constrain these small changes with full radiative transfer analyses of each of the thousands of VIMS spectra, which were recorded of different terrains and at different lighting conditions. The resulting models of Titan’s atmosphere as a function of latitude and year indicate the seasonal migration of Titan’s tropical haze and enable the derivation of Titan’s surface albedo at 8 near-IR wavelength regions where Titan’s atmosphere is transparent enough to allow visibility to the surface. The resultant maps of Titan’s surface indicate a number of terrain types with distinct spectral characteristics that are suggestive of atmospheric and surficial processes, including the deposition of organic material, erosion of

  12. Surface-modified gold nanoshells for enhanced cellular uptake.

    PubMed

    Liang, Zhongshi; Liu, Yun; Li, Xiangyang; Wu, Qinge; Yu, Jiahui; Luo, Shufang; Lai, Lihui; Liu, Shunying

    2011-09-15

    Gold nanoshells have shown a great potential for use as agents in a wide variety of biomedical applications, and some of which require the delivery of large numbers of gold nanoshells onto or into the cells. Here, we develop a ready method to enhance the cellular uptake of gold nanoshells by modifying with meso-2,3-dimercaptosuccinic acid (DMSA). The quantifiable technique of inductively coupled plasma atomic emissions spectroscopy (ICP-AES) and transmission electron microscopy (TEM) were used to investigate the cellular uptake of unmodified and DMSA-modified gold nanoshells. Three cell lines (RAW 264.7, A549, and BEL-7402) were involved and the results indicated that the cellular uptake of the DMSA-modified gold nanoshells was obviously enhanced versus the unmodified gold nanoshells. The reason possibly lies in the nonspecific adsorption of serum protein on the DMSA-modified gold nanoshells (DMSA-GNs), which consequently enhanced the cellular uptake. As a continued effort, in vitro experiments with endocytic inhibitors suggested the DMSA-GNs internalized into cells via receptor-mediated endocytosis (RME) pathway. This study has provided a valuable insight into the effects of surface modification on cellular uptake of nanoparticles.

  13. Cell surface-mediated cellular interactions: effects of B104 neuroblastoma surface determinants on C6 glioma cellular properties.

    PubMed

    Ciment, G; de Vellis, J

    1982-01-01

    To study the influence of cell surface-associated molecules on intercellular communication, C6 glioma cells were cultured both on plastic and on substrata of paraformaldehyde-fixed B104 neuroblastoma cells. By then comparing the phenotypic expression of these "cocultured" C6 cells with cells cultured on tissue culture plastic, the influence of the cellular substratum was determined. The beta-adrenergic-responsive cyclic AMP-generating system of C6 cells was compared on these various substrata. We found that fixed beds of dibutyryl cyclic AMP (dbcAMP)-treated B104 cells uncoupled beta-receptors from adenylate cyclase, whereas fixed beds of similarly treated C6 cells did not. However, other cellular properties were not affected by growth atop fixed dbcAMP-treated B104 cell beds including the rate of C6 cellular proliferation and their rate of protein synthesis. The cell surface-associated determinant on B104 cells capable of uncoupling the beta-responsive cyclase system of C6 cells is probably a protein, as judged by its susceptibility to protease treatment. Other properties of C6 cells were also affected by the various substrata including basal and hydrocortisone-induced levels of glycerol phosphate dehydrogenase (GPDH; an oligodendroglial marker) and the rate of RNA synthesis in these cells.

  14. Surface modifications of silicon nitride for cellular biosensor applications.

    PubMed

    Gustavsson, Johan; Altankov, George; Errachid, Abdelhamid; Samitier, Josep; Planell, Josep A; Engel, Elisabeth

    2008-04-01

    Thin films of silicon nitride (Si3N4) can be used in several kinds of micro-sized biosensors as a material to monitor fine environmental changes related to the process of bone formation in vitro. We found however that Si3N4 does not provide optimal conditions for osseointegration as osteoblast-like MG-63 cells tend to detach from the surface when cultured over confluence. Therefore Si3N4 was modified with self-assembled monolayers bearing functional end groups of primary amine (NH2) and carboxyl (COOH) respectively. Both these modifications enhanced the interaction with confluent cell layers and thus improve osseointegration over Si3N4. Furthermore it was observed that the NH2 functionality increased the adsorption of fibronectin (FN), promoted cell proliferation, but delayed the differentiation. We also studied the fate of pre-adsorbed and secreted FN from cells to learn more about the impact of above functionalities for the development of provisional extracellular matrix on materials interface. Taken together our data supports that Si3N4 has low tissue integration but good cellular biocompatibility and thus is appropriate in cellular biosensor applications such as the ion-sensitive field effect transistor (ISFET). COOH and NH2 chemistries generally improve the interfacial tissue interaction with the sensor and they are therefore suitable substrates for monitoring cellular growth or matrix deposition using electrical impedance spectroscopy.

  15. Optofluidic cellular immunofunctional analysis by localized surface plasmon resonance

    NASA Astrophysics Data System (ADS)

    Kurabayashi, Katsuo; Oh, Bo-Ram

    2014-08-01

    Cytokine secretion assays provide the means to quantify intercellular-signaling proteins secreted by blood immune cells. These assays allow researchers and clinicians to obtain valuable information on the immune status of the donor. Previous studies have demonstrated that localized surface plasmon resonance (LSPR) effects enable label-free, real-time biosensing on a nanostructured metallic surface with simple optics and sensing tunability. However, limited sensitivity coupled with a lack of sample handling capability makes it challenging to implement LSPR biosensing in cellular functional immunoanalysis based on cytokine secretion assay. This paper describes our recent progress towards full development of a label-free LSPR biosensing technique to detect cell-secreted tumor necrosis factor (TNF)-α cytokines in clinical blood samples. We integrate LSPR bionanosensors in an optofluidic platform capable of handling target immune cells in a microfluidic chamber while readily permitting optical access for cytokine detection.

  16. The Design and Performance Characteristics of a Cellular Logic 3-D Image Classification Processor.

    DTIC Science & Technology

    1981-04-01

    number) Pattern Recognition Cellular Automata " Cellular Logic Target Classificatio4 1Neighborhood Transformation Image Processing Laser Radar iASSTRACT...AND PERFORMANCE CHARACTERISTICS OF A CELLULAR LOGIC 3-D IMAGE CLASSIFICATION PROCESSOR 1 &/. , DISSERTATION AFIT/DS/EE/81-1 Lawrence A. Ankeney... CELLULAR LOGIC 3-D IMAGE - -- A&I PRCSRDTIC T B CLASSIFICATION PROCESSOR Unannounced 0 Justificatio b yD t i u i n Lawrence A. Ankeney, B.S., M.S

  17. A cellular automata approach for modeling surface water runoff

    NASA Astrophysics Data System (ADS)

    Jozefik, Zoltan; Nanu Frechen, Tobias; Hinz, Christoph; Schmidt, Heiko

    2015-04-01

    This abstract reports the development and application of a two-dimensional cellular automata based model, which couples the dynamics of overland flow, infiltration processes and surface evolution through sediment transport. The natural hill slopes are represented by their topographic elevation and spatially varying soil properties infiltration rates and surface roughness coefficients. This model allows modeling of Hortonian overland flow and infiltration during complex rainfall events. An advantage of the cellular automata approach over the kinematic wave equations is that wet/dry interfaces that often appear with rainfall overland flows can be accurately captured and are not a source of numerical instabilities. An adaptive explicit time stepping scheme allows for rainfall events to be adequately resolved in time, while large time steps are taken during dry periods to provide for simulation run time efficiency. The time step is constrained by the CFL condition and mass conservation considerations. The spatial discretization is shown to be first-order accurate. For validation purposes, hydrographs for non-infiltrating and infiltrating plates are compared to the kinematic wave analytic solutions and data taken from literature [1,2]. Results show that our cellular automata model quantitatively accurately reproduces hydrograph patterns. However, recent works have showed that even through the hydrograph is satisfyingly reproduced, the flow field within the plot might be inaccurate [3]. For a more stringent validation, we compare steady state velocity, water flux, and water depth fields to rainfall simulation experiments conducted in Thies, Senegal [3]. Comparisons show that our model is able to accurately capture these flow properties. Currently, a sediment transport and deposition module is being implemented and tested. [1] M. Rousseau, O. Cerdan, O. Delestre, F. Dupros, F. James, S. Cordier. Overland flow modeling with the Shallow Water Equation using a well balanced

  18. Charged group surface accessibility determines micelleplexes formation and cellular interaction

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Liu, Yang; Sen, Soumyo; Král, Petr; Gemeinhart, Richard A.

    2015-04-01

    Micelleplexes are a class of nucleic acid carriers that have gained acceptance due to their size, stability, and ability to synergistically carry small molecules. MicroRNAs (miRNAs) are small non-coding RNA gene regulator that is consists of 19-22 nucleotides. Altered expression of miRNAs plays an important role in many human diseases. Using a model 22-nucleotide miRNA sequence, we investigated the interaction between charged groups on the micelle surface and miRNA. The model micelle system was formed from methoxy-poly(ethylene glycol)-b-poly(lactide) (mPEG-PLA) mixed with methoxy-poly(ethylene glycol)-b-poly(lactide)-b-oligoarginine (mPEG-PLA-Rx, x = 8 or 15). Surface properties of the micelles were varied by controlling the oligoarginine block length and conjugation density. Micelles were observed to have a core-shell conformation in the aqueous environment where the PLA block constituted the hydrophobic core, mPEG and oligoarginine formed a hydrophilic corona. Significantly different thermodynamic behaviors were observed during the interaction of single stranded miRNA with micelles of different surface properties, and the resulting micelleplexes mediated substantial cellular association. Depending upon the oligoarginine length and density, micelles exhibited miRNA loading capacity directly related to the presentation of charged groups on the surface. The effect of charged group accessibility of cationic micelle on micelleplex properties provides guidance on future miRNA delivery system design.Micelleplexes are a class of nucleic acid carriers that have gained acceptance due to their size, stability, and ability to synergistically carry small molecules. MicroRNAs (miRNAs) are small non-coding RNA gene regulator that is consists of 19-22 nucleotides. Altered expression of miRNAs plays an important role in many human diseases. Using a model 22-nucleotide miRNA sequence, we investigated the interaction between charged groups on the micelle surface and miRNA. The

  19. Cellular interactions of surface modified nanoporous silicon particles

    NASA Astrophysics Data System (ADS)

    Bimbo, Luis M.; Sarparanta, Mirkka; Mäkilä, Ermei; Laaksonen, Timo; Laaksonen, Päivi; Salonen, Jarno; Linder, Markus B.; Hirvonen, Jouni; Airaksinen, Anu J.; Santos, Hélder A.

    2012-05-01

    In this study, the self-assembly of hydrophobin class II (HFBII) on the surface of thermally hydrocarbonized porous silicon (THCPSi) nanoparticles was investigated. The HFBII-coating converted the hydrophobic particles into more hydrophilic ones, improved the particles' cell viability in both HT-29 and Caco-2 cell lines compared to uncoated particles, and enhanced the particles' cellular association. The amount of HFBII adsorbed onto the particles was also successfully quantified by both the BCA assay and a HPLC method. Importantly, the permeation of a poorly water-soluble drug, indomethacin, loaded into THCPSi particles across Caco-2 monolayers was not affected by the protein coating. In addition, 125I-radiolabelled HFBII did not extensively permeate the Caco-2 monolayer and was found to be stably adsorbed onto the THCPSi nanoparticles incubated in pH 7.4, which renders the particles the possibility for further track-imaging applications. The results highlight the potential of HFBII coating for improving wettability, increasing biocompatibility and possible intestinal association of PSi nanoparticulates for drug delivery applications.In this study, the self-assembly of hydrophobin class II (HFBII) on the surface of thermally hydrocarbonized porous silicon (THCPSi) nanoparticles was investigated. The HFBII-coating converted the hydrophobic particles into more hydrophilic ones, improved the particles' cell viability in both HT-29 and Caco-2 cell lines compared to uncoated particles, and enhanced the particles' cellular association. The amount of HFBII adsorbed onto the particles was also successfully quantified by both the BCA assay and a HPLC method. Importantly, the permeation of a poorly water-soluble drug, indomethacin, loaded into THCPSi particles across Caco-2 monolayers was not affected by the protein coating. In addition, 125I-radiolabelled HFBII did not extensively permeate the Caco-2 monolayer and was found to be stably adsorbed onto the THCPSi

  20. The gingival Stillman’s clefts: histopathology and cellular characteristics

    PubMed Central

    Cassini, Maria Antonietta; Cerroni, Loredana; Ferlosio, Amedeo; Orlandi, Augusto; Pilloni, Andrea

    2015-01-01

    Summary Aim of the study Stillman’s cleft is a mucogingival triangular-shaped defect on the buccal surface of a root with unknown etiology and pathogenesis. The aim of this study is to examine the Stillman’s cleft obtained from excision during root coverage surgical procedures at an histopathological level. Materials and method Harvesting of cleft was obtained from two periodontally healthy patients with a scalpel and a bevel incision and then placed in a test tube with buffered solution to be processed for light microscopy. Results Microscopic analysis has shown that Stillman’s cleft presented a lichenoid hand-like inflammatory infiltration, while in the periodontal patient an inflammatory fibrous hyperplasia was identified. Conclusion Stillman’s cleft remains to be investigated as for the possible causes of such lesion of the gingival margin, although an inflammatory response seems to be evident and active from a strictly histopathological standpoint. PMID:26941897

  1. Tailoring hydrogel surface properties to modulate cellular response to shear loading.

    PubMed

    Meinert, Christoph; Schrobback, Karsten; Levett, Peter A; Lutton, Cameron; Sah, Robert L; Klein, Travis J

    2016-10-08

    Biological tissues at articulating surfaces, such as articular cartilage, typically have remarkable low-friction properties that limit tissue shear during movement. However, these frictional properties change with trauma, aging, and disease, resulting in an altered mechanical state within the tissues. Yet, it remains unclear how these surface changes affect the behaviour of embedded cells when the tissue is mechanically loaded. Here, we developed a cytocompatible, bilayered hydrogel system that permits control of surface frictional properties without affecting other bulk physicochemical characteristics such as compressive modulus, mass swelling ratio, and water content. This hydrogel system was applied to investigate the effect of variations in surface friction on the biological response of human articular chondrocytes to shear loading. Shear strain in these hydrogels during dynamic shear loading was significantly higher in high-friction hydrogels than in low-friction hydrogels. Chondrogenesis was promoted following dynamic shear stimulation in chondrocyte-encapsulated low-friction hydrogel constructs, whereas matrix synthesis was impaired in high-friction constructs, which instead exhibited increased catabolism. Our findings demonstrate that the surface friction of tissue-engineered cartilage may act as a potent regulator of cellular homeostasis by governing the magnitude of shear deformation during mechanical loading, suggesting a similar relationship may also exist for native articular cartilage.

  2. Processing Characteristics and Properties of the Cellular Products Made by Using Special Foaming Agents

    NASA Astrophysics Data System (ADS)

    Garbacz, Tomasz; Dulebova, Ludmila

    2012-12-01

    The paper describes the manufacturing process of extruded products by the cellular extrusion method, and presents specifications of the blowing agents used in the extrusion process as well as process conditions. The process of cellular extrusion of thermoplastic materials is aimed at obtaining cellular shapes and coats with reduced density, presenting no hollows on the surface of extruder product and displaying minimal contraction under concurrent maintenance of properties similar to properties of products extruded by means of the conventional method. In order to obtain cellular structure, the properties of extruded product are modified by applying suitable plastic or inserting auxiliary agents.

  3. Identifying Changes in Snowpack Surface Roughness Characteristics

    NASA Astrophysics Data System (ADS)

    Fassnacht, S. R.; Corrao, M. V.; Deems, J. S.; Stednick, J. D.

    2006-12-01

    The flow of air over a surface is influenced by its roughness. The surface of a snowpack is smooth relative to the underlying ground surface. The relative roughness of the snowpack surface changes directionally, spatially, and temporally, due to deposition, erosion, and melt. To examine these changes in snowpack surface roughness at the microtopographic scale for a Northern Colorado site, the surface was photographed using a darker-coloured roughness board that was inserted into the snowpack so that a black (board) versus white (snow) contrast existed along the entire length of the board. The board was 1-m long and was inserted 11 times at 10-cm intervals to create a 1-m by 1-m mesh. The orientation of the boards was rotated 90 degrees to provide finer resolution data in perpendicular directions. For the 1-m boards, the pixel resolution was approximately 0.4 mm. To measure the snow grain scale, a crystal card was photographed and yielded a pixel resolution of approximately 0.1 mm. Incorporating image processing issues such as image contrast and brightness, the digital images were translated into individual lines. These lines were used to compute semi- variograms in log-log space, from which the magnitude of semi-variance, the fractal dimensions, and the scale break were computed. The semi-variogram characteristics were used to illustrate directional, spatial, and temporal changes in snowpack surface roughness.

  4. Near surface characteristics of foehn winds

    NASA Astrophysics Data System (ADS)

    Stiperski, Ivana

    2015-04-01

    Downslope windstorms occur commonly in mountainous regions around the world. Their importance is particularly great for air traffic, as well as wind energy, air pollution but also for ice shelf stability in the Antarctica, or deep water formation of the mountainous coasts. In this work we will focus on the foehn type of downslope windstorms and examine it's near surface turbulence characteristics in the Inn Valley, Austria. The foehn in the Inn Valley has been extensively studied throughout the past century, especially in several intensive campaigns. However, the smaller scale turbulence characteristics have only received limited attention. Here we present results from foehn episodes spanning over a year of data. The turbulence measurements at 5 stations within the Inn Valley, Austria as part of the i-Box project are used for the analysis. The general near surface turbulence characteristics of these events are examined and the characteristic scales of dominant transport are determined. Their dependence to horizontal heterogeneity is investigated both on the mesoscale and sub-mesoscale. Special focus is places on the question of energy balance closure during foehn episodes and the influence of advection.

  5. Controlling cellular activity by manipulating silicone surface roughness.

    PubMed

    Prasad, Babu R; Brook, Michael A; Smith, Terry; Zhao, Shigui; Chen, Yang; Sheardown, Heather; D'souza, Renita; Rochev, Yuri

    2010-07-01

    Silicone elastomers exhibit a broad range of beneficial properties that are exploited in biomaterials. In some cases, however, problems can arise at silicone elastomer interfaces. With breast implants, for example, the fibrous capsule that forms at the silicone interface can undergo contracture, which can lead to the need for revision surgery. The relationship between surface topography and wound healing--which could impact on the degree of contracture--has not been examined in detail. To address this, we prepared silicone elastomer samples with rms surface roughnesses varying from 88 to 650 nm and examined the growth of 3T3 fibroblasts on these surfaces. The PicoGreen assay demonstrated that fibroblast growth decreased with increases in surface roughness. Relatively smooth (approximately 88 nm) PDMS samples had ca. twice as much fibroblast DNA per unit area than the 'bumpy' (approximately 378 nm) and very rough (approximately 604 and approximately 650 nm) PDMS samples. While the PDMS sample with roughness of approximately 650 nm had significantly fewer fibroblasts at 24h than the TCP control, fibroblasts on the smooth silicone surprisingly reached confluence much more rapidly than on TCP, the gold standard for cell culture. Thus, increasing the surface roughness at the sub-micron scale could be a strategy worthy of consideration to help mitigate fibroblast growth and control fibrous capsule formation on silicone elastomer implants.

  6. Effects of surface viscoelasticity on cellular responses of endothelial cells

    PubMed Central

    Hosseini, Motahare-Sadat; Katbab, Ali Asghar

    2014-01-01

    Background: One area of nanoscience deals with nanoscopic interactions between nanostructured materials and biological systems. To elucidate the effects of the substrate surface morphology and viscoelasticity on cell proliferation, fractal analysis was performed on endothelial cells cultured on nanocomposite samples based on silicone rubber (SR) and various concentrations of organomodified nanoclay (OC). Methods: The nanoclay/SR ratio was tailored to enhance cell behavior via changes in sample substrate surface roughness and viscoelasticity. Results: Surface roughness of the cured SR filled with negatively-charged nanosilicate layers had a greater effect than elasticity on cell growth. The surface roughness of SR nanocomposite samples increased with increasing the OC content, leading to enhanced cell growth and extracellular matrix (ECM) remodeling. This was consistent with the decrease in SR segmental motions and damping factor as the primary viscoelastic parameters by the nanosilicate layers with increasing clay concentrations. Conclusions: The inclusion of clay nanolayers affected the growth and behavior of endothelial cells on microtextured SR. PMID:26989733

  7. Transient partial permeabilization with saponin enables cellular barcoding prior to surface marker staining1

    PubMed Central

    Behbehani, Gregory K.; Thom, Colin; Zunder, Eli R.; Finck, Rachel; Gaudilliere, Brice; Fragiadakis, Gabriela K.; Fantl, Wendy J.; Nolan, Garry P.

    2015-01-01

    Fluorescent cellular barcoding and mass-tag cellular barcoding are cytometric methods that enable high sample throughput, minimize inter-sample variation, and reduce reagent consumption. Previously employed barcoding protocols require that barcoding be performed after surface marker staining, complicating combining the technique with measurement of alcohol-sensitive surface epitopes. This report describes a method of barcoding fixed cells after a transient partial permeabilization with 0.02% saponin that results in efficient and consistent barcode staining with fluorescent or mass-tagged reagents while preserving surface marker staining. This approach simplifies barcoding protocols and allows direct comparison of surface marker staining of multiple samples without concern for variations in the antibody cocktail volume, antigen-antibody ratio, or machine sensitivity. Using this protocol, cellular barcoding can be used to reliably detect subtle differences in surface marker expression. PMID:25274027

  8. Tuning cellular responses to BMP-2 with material surfaces

    PubMed Central

    Picart, Catherine; Cavalcanti-Adam, Elisabetta Ada

    2016-01-01

    Bone morphogenetic protein 2 (BMP-2) has been known for decades as a strong osteoinductive factor and for clinical applications is combined solely with collagen as carrier material. The growing concerns regarding side effects and the importance of BMP-2 in several developmental and physiological processes have raised the need to improve the design of materials by controlling BMP-2 presentation. Inspired by the natural cell environment, new material surfaces have been engineered and tailored to provide both physical and chemical cues that regulate BMP-2 activity. Here we describe surfaces designed to present BMP-2 to cells in a spatially and temporally controlled manner. This is achieved by trapping BMP-2 using physicochemical interactions, either covalently grafted or combined with other extracellular matrix components. In the near future, we anticipate that material science and biology will integrate and further develop tools for in vitro studies and potentially bring some of them toward in vivo applications. PMID:26704296

  9. Characteristics of Surface Sterilization using ECR Plasma

    NASA Astrophysics Data System (ADS)

    Yonesu, Akira; Hara, Kazufumi; Nishikawa, Tatsuya; Hayashi, Nobuya

    2015-09-01

    Plasma sterilization techniques have superior characteristics such as a short treatment times, non-toxicity and low thermal damages on the sterilized materials. In plasma sterilization, microorganisms can be sterilized by active radicals, energetic charged particles, and vacuum UV radiation. The influence of each factor depends on the plasma operating parameters. Microwave discharges under the electron cyclotron resonance (ECR) condition produce higher electron temperature and density plasma as compared with other plasma generation techniques. In the present study, characteristics of surface sterilization using ECR plasma have been investigated.The experiment was performed in the vacuum chamber which contains a magnet holder. A pair of rectangular Sm-Co permanent magnets is aligned parallel to each other within the magnet holder. The region of the magnetic field for ECR exists near the magnet holder surface. When the microwave is introduced into the vacuum chamber, a ECR plasma is produced around surface of the magnet holder. High energy electrons and oxygen radicals were observed at ECR zone by electric probe method and optical spectroscopic method. Biological indicators (B.I.) having spore of 106 was sterilized in 2min for oxygen discharge. The temperature of the B.I. installation position was about 55°. The sterilization was achieved by the effect of oxygen radicals and high energy electrons.

  10. Characteristics of near-surface electrokinetic coupling

    NASA Astrophysics Data System (ADS)

    Beamish, David

    1999-04-01

    Naturally occurring electric potentials at the Earth's surface are traditionally studied using self-potential geophysics. Recent theoretical and experimental work has reinvestigated the manner in which the measurement can be made dynamically using a pressure source. The methodology, often referred to as seismoelectric, relies on electrokinetic coupling at interfaces in the streaming potential coefficient. The ultimate aim of the developing methodologies lies in the detection of zones of high fluid mobility (permeability) and fluid geochemical contrasts within the subsurface. As yet there are no standard methods of recording and interpretation: the technique remains experimental. Field measurements are made using a seismic source and by recording electric voltage across arrays of surface dipoles. This study presents observational characteristics of electrokinetic coupling based on experiments carried out in a wide range of environments. Theory concerning the coupled elastic and electromagnetic wave equations in a saturated porous medium is discussed. It is predicted that coupling will produce electromagnetic radiation patterns from vertical electric dipoles generated at interfaces. Surface- and body-wave coupling mechanisms should provide different time-distance patterns. Vertical electric dipole radiation sources are modelled and their spatial characteristics presented. A variety of experimental configurations have been used, and geometries that exploit phase asymmetry to enhance the separation of signal and noise are emphasized. The main experimental results presented are detailed observations in the immediate vicinity of the source. Simultaneous arrivals across arrays of surface dipoles are not common. The majority of such experiments have indicated that shot-symmetric voltages which display low-velocity moveout are the dominant received waveforms.

  11. Dispersion and surface characteristics of nanosilica suspensions.

    PubMed

    Kumar, Ranganathan; Milanova, Denitsa

    2009-04-01

    Nanofluids consisting of nanometer-sized particles dispersed in base liquids are known to be effective in extending the saturated boiling regime and critical heat flux in pool boiling. The heat transfer characteristics of nanosilica suspensions with particle sizes of 10 and 20 nm in pool boiling with a suspended heating Nichrome wire have been analyzed. The pH value of the nanosuspensions is important from the point of view that it determines the stability of the particles and their mutual interactions toward the suspended heated wire. When silica is suspended in water with no additives, the surface potential of the nanoparticles determines their movement toward the electrodes. Particles continuously deposit on the wire and extend the burnout heat flux, influenced by the chemical composition of the nanofluids. This agglomeration allows high heat transfer through interagglomerate pores, resulting in a nearly threefold increase in burnout heat flux. Particle size, zeta potential, and the burnout heat flux values under different volume concentrations are provided. The burnout heat flux of the wire does not increase monotonically with concentration, but depends on the agglomeration characteristics, particle shape, and the hydroxylated surface of the nanoparticles.

  12. Effect of MWCNT surface and chemical modification on in vitro cellular response

    NASA Astrophysics Data System (ADS)

    Fraczek-Szczypta, Aneta; Menaszek, Elzbieta; Syeda, Tahmina Bahar; Misra, Anil; Alavijeh, Mohammad; Adu, Jimi; Blazewicz, Stanislaw

    2012-10-01

    The aim of this study was to evaluate the impact of multi-walled carbon nanotubes (MWCNTs with diameter in the range of 10-30 nm) before and after chemical surface functionalisation on macrophages response. The study has shown that the detailed analysis of the physicochemical properties of this particular form of carbon nanomaterial is a crucial issue to interpret properly its impact on the cellular response. Effects of carbon nanotubes (CNTs) characteristics, including purity, dispersity, chemistry and dimension upon the nature of the cell environment-material interaction were investigated. Various techniques involving electron microscopy (SEM, TEM), infrared spectroscopy (FTIR), inductively coupled plasma optical emission spectrometry, X-ray photoelectron spectroscopy have been employed to evaluate the physicochemical properties of the materials. The results demonstrate that the way of CNT preparation prior to biological tests has a fundamental impact on their behavior, cell viability and the nature of cell-nanotube interaction. Chemical functionalisation of CNTs in an acidic ambient (MWCNT-Fs) facilitates interaction with cells by two possible mechanisms, namely, endocytosis/phagocytosis and by energy-independent passive process. The results indicate that MWCNT-F in macrophages may decrease the cell proliferation process by interfering with the mitotic apparatus without negative consequences on cell viability. On the contrary, the as-prepared MWCNTs, without any surface treatment produce the least reduction in cell proliferation with reference to control, and the viability of cells exposed to this sample was substantially reduced with respect to control. A possible explanation of such a phenomenon is the presence of MWCNT's agglomerates surrounded by numerous cells releasing toxic substances.

  13. Surface topography and chemistry shape cellular behavior on wide band-gap semiconductors.

    PubMed

    Bain, Lauren E; Collazo, Ramon; Hsu, Shu-Han; Latham, Nicole Pfiester; Manfra, Michael J; Ivanisevic, Albena

    2014-06-01

    The chemical stability and electrical properties of gallium nitride make it a promising material for the development of biocompatible electronics, a range of devices including biosensors as well as interfaces for probing and controlling cellular growth and signaling. To improve the interface formed between the probe material and the cell or biosystem, surface topography and chemistry can be applied to modify the ways in which the device interacts with its environment. PC12 cells are cultured on as-grown planar, unidirectionally polished, etched nanoporous and nanowire GaN surfaces with and without a physisorbed peptide sequence that promotes cell adhesion. While cells demonstrate preferential adhesion to roughened surfaces over as-grown flat surfaces, the topography of that roughness also influences the morphology of cellular adhesion and differentiation in neurotypic cells. Addition of the peptide sequence generally contributes further to cellular adhesion and promotes development of stereotypic long, thin neurite outgrowths over alternate morphologies. The dependence of cell behavior on both the topographic morphology and surface chemistry is thus demonstrated, providing further evidence for the importance of surface modification for modulating bio-inorganic interfaces.

  14. Characteristic variations in reflectance of surface soils

    NASA Technical Reports Server (NTRS)

    Stoner, E. R.; Baumgardner, M. F. (Principal Investigator)

    1982-01-01

    Surface soil samples from a wide range of naturally occurring soils were obtained for the purpose of studying the characteristic variations in soil reflectance as these variations relate to other soil properties and soil classification. A total 485 soil samples from the U.S. and Brazil representing 30 suborders of the 10 orders of 'Soil Taxonomy' was examined. The spectral bidirectional reflectance factor was measured on uniformly moist soils over the 0.52 to 2.32 micron wavelength range with a spectroradiometer adapted for indoor use. Five distinct soil spectral reflectance curve forms were identified according to curve shape, the presence or absence of absorption bands, and the predominance of soil organic matter and iron oxide composition. These curve forms were further characterized according to generically homogeneous soil properties in a manner similar to the subdivisions at the suborder level of 'Soil Taxonomy'. Results indicate that spectroradiometric measurements of soil spectral bidirectional reflectance factor can be used to characterize soil reflectance in terms that are meaningful to soil classification, genesis, and survey.

  15. Folding, But Not Surface Area Expansion, Is Associated with Cellular Morphological Maturation in the Fetal Cerebral Cortex.

    PubMed

    Wang, Xiaojie; Studholme, Colin; Grigsby, Peta L; Frias, Antonio E; Cuzon Carlson, Verginia C; Kroenke, Christopher D

    2017-02-22

    Altered macroscopic anatomical characteristics of the cerebral cortex have been identified in individuals affected by various neurodevelopmental disorders. However, the cellular developmental mechanisms that give rise to these abnormalities are not understood. Previously, advances in image reconstruction of diffusion magnetic resonance imaging (MRI) have made possible high-resolution in utero measurements of water diffusion anisotropy in the fetal brain. Here, diffusion anisotropy within the developing fetal cerebral cortex is longitudinally characterized in the rhesus macaque, focusing on gestation day (G85) through G135 of the 165 d term. Additionally, for subsets of animals characterized at G90 and G135, immunohistochemical staining was performed, and 3D structure tensor analyses were used to identify the cellular processes that most closely parallel changes in water diffusion anisotropy with cerebral cortical maturation. Strong correlations were found between maturation of dendritic arbors on the cellular level and the loss of diffusion anisotropy with cortical development. In turn, diffusion anisotropy changes were strongly associated both regionally and temporally with cortical folding. Notably, the regional and temporal dependence of diffusion anisotropy and folding were distinct from the patterns observed for cerebral cortical surface area expansion. These findings strengthen the link proposed in previous studies between cellular-level changes in dendrite morphology and noninvasive diffusion MRI measurements of the developing cerebral cortex and support the possibility that, in gyroencephalic species, structural differentiation within the cortex is coupled to the formation of gyri and sulci.SIGNIFICANCE STATEMENT Abnormal brain morphology has been found in populations with neurodevelopmental disorders. However, the mechanisms linking cellular level and macroscopic maturation are poorly understood, even in normal brains. This study contributes new

  16. Surface modification of a POSS-nanocomposite material to enhance cellular integration of a synthetic bioscaffold

    PubMed Central

    Crowley, Claire; Klanrit, Poramate; Butler, Colin R.; Varanou, Aikaterini; Platé, Manuela; Hynds, Robert E.; Chambers, Rachel C.; Seifalian, Alexander M.; Birchall, Martin A.; Janes, Sam M.

    2016-01-01

    Polyhedral oligomeric silsesquioxane poly(carbonate-urea) urethane (POSS-PCU) is a versatile nanocomposite biomaterial with growing applications as a bioscaffold for tissue engineering. Integration of synthetic implants with host tissue can be problematic but could be improved by topographical modifications. We describe optimization of POSS-PCU by dispersion of porogens (sodium bicarbonate (NaHCO3), sodium chloride (NaCl) and sucrose) onto the material surface, with the principle aim of increasing surface porosity, thus providing additional opportunities for improved cellular and vascular ingrowth. We assess the effect of the porogens on the material's mechanical strength, surface chemistry, wettability and cytocompatibilty. Surface porosity was characterized by scanning electron microscopy (SEM). There was no alteration in surface chemistry and wettability and only modest changes in mechanical properties were detected. The size of porogens correlated well with the porosity of the construct produced and larger porogens improved interconnectivity of spaces within constructs. Using primary human bronchial epithelial cells (HBECs) we demonstrate moderate in vitro cytocompatibility for all surface modifications; however, larger pores resulted in cellular aggregation. These cells were able to differentiate on POSS-PCU scaffolds. Implantation of the scaffold in vivo demonstrated that larger pore sizes favor cellular integration and vascular ingrowth. These experiments demonstrate that surface modification with large porogens can improve POSS-PCU nanocomposite scaffold integration and suggest the need to strike a balance between the non-porous surfaces required for epithelial coverage and the porous structure required for integration and vascularization of synthetic scaffolds in future construct design. PMID:26790147

  17. Cellular and Mitochondrial Dual-Targeted Organic Dots with Aggregation-Induced Emission Characteristics for Image-Guided Photodynamic Therapy.

    PubMed

    Feng, Guangxue; Qin, Wei; Hu, Qinglian; Tang, Ben Zhong; Liu, Bin

    2015-12-09

    Targeted delivery of drugs toward mitochondria of specific cancer cells dramatically improves therapy efficiencies especially for photodynamic therapy (PDT), as reactive oxygen species (ROS) are short in lifetime and small in radius of action. Different from chemical modification, nanotechnology has been serving as a simple and nonchemical approach to deliver drugs to cells of interest or specific organelles, such as mitochondria, but there have been limited examples of dual-targeted delivery for both cells and mitochondria. Here, cellular and mitochondrial dual-targeted organic dots for image-guided PDT are reported based on a fluorogen with aggregation-induced emission (AIEgen) characteristics. The AIEgen possesses enhanced red fluorescence and efficient ROS production in aggregated states. The AIE dot surfaces are functionalized with folate and triphenylphosphine, which can selectively internalize into folate-receptor (FR) positive cancer cells, and subsequently accumulate at mitochondria. The direct ROS generation at mitochondria sites is found to depolarize mitochondrial membrane, affect cell migration, and lead to cell apoptosis and death with enhanced PDT effects as compared to ROS generated randomly in cytoplasm. This report demonstrates a simple and general nanocarrier approach for cellular and mitochondrial dual-targeted PDT, which opens new opportunities for dual-targeted delivery and therapy.

  18. Influence of surface passivation of 2-Methoxyestradiol loaded PLGA nanoparticles on cellular interactions, pharmacokinetics and tumour accumulation.

    PubMed

    Pillai, Gopikrishna J; Paul-Prasanth, Bindhu; Nair, Shantikumar V; Menon, Deepthy

    2017-02-01

    In the present work, 2-Methoxyestradiol [2ME2] loaded PLGA nanoparticles [NPs] were stabilized with Casein or poly(ethylene glycol) [PEG] and evaluated for its cellular interactions, pharmacokinetics and tumour accumulation. Surface stabilized PLGA nanoparticles prepared through a modified emulsion route possessed similar size, surface charge, drug loading and release characteristics. Particle-cell interactions as well as the anti-angiogenesis activity were similar for both nanoformulations in vitro. However, in vivo pharmacokinetics and tumour accumulation of the drug were substantially improved for the PEGylated nanoformulation. Reduced protein binding was observed for PEG stabilized PLGA NPs. Thus, it was demonstrated that nanoencapsulation of 2-ME2 within PEGylated PLGA nanocarrier could improve its half-life and plasma concentration and thereby increase the tumour accumulation.

  19. Adsorption at cell surface and cellular uptake of silica nanoparticles with different surface chemical functionalizations: impact on cytotoxicity

    NASA Astrophysics Data System (ADS)

    Kurtz-Chalot, A.; Klein, J. P.; Pourchez, J.; Boudard, D.; Bin, V.; Alcantara, G. B.; Martini, M.; Cottier, M.; Forest, V.

    2014-11-01

    Silica nanoparticles are particularly interesting for medical applications because of the high inertness and chemical stability of silica material. However, at the nanoscale their innocuousness must be carefully verified before clinical use. The aim of this study was to investigate the in vitro biological toxicity of silica nanoparticles depending on their surface chemical functionalization. To that purpose, three kinds of 50 nm fluorescent silica-based nanoparticles were synthesized: (1) sterically stabilized silica nanoparticles coated with neutral polyethylene glycol molecules, (2) positively charged silica nanoparticles coated with amine groups, and (3) negatively charged silica nanoparticles coated with carboxylic acid groups. RAW 264.7 murine macrophages were incubated for 20 h with each kind of nanoparticles. Their cellular uptake and adsorption at the cell membrane were assessed by a fluorimetric assay, and cellular responses were evaluated in terms of cytotoxicity, pro-inflammatory factor production, and oxidative stress. Results showed that the highly positively charged nanoparticle were the most adsorbed at cell surface and triggered more cytotoxicity than other nanoparticle types. To conclude, this study clearly demonstrated that silica nanoparticles surface functionalization represents a key parameter in their cellular uptake and biological toxicity.

  20. Surface characteristics of PLA and PLGA films

    NASA Astrophysics Data System (ADS)

    Paragkumar N, Thanki; Edith, Dellacherie; Six, Jean-Luc

    2006-12-01

    Surface segregation and restructuring in polylactides (poly( D, L-lactide) and poly( L-lactide)) and poly( D,L-lactide-co-glycolide) (PLGA) films of various thicknesses were investigated using both attenuated total reflection FTIR (ATR-FTIR) and contact angle relaxation measurements. In case of poly( D,L-lactide) (DLPLA), it was observed that the surface segregation and the surface restructuring of methyl side groups are influenced by the polymer film thickness. This result has been confirmed by X-ray photoelectron spectroscopy (XPS). In the same way, PLGA thick films were also characterized by an extensive surface segregation of methyl side groups. Finally, surface restructuring was investigated by dynamic contact angle measurements and it was observed when film surface comes into contact with water. In parallel, we also found that poly( L-lactide) (PLLA) thin and clear films with thickness ˜15 μm undergo conformational changes on the surface upon solvent treatment with certain solvents. The solvent treated surface of PLLA becomes hazy and milky white and its hydrophobicity increases compared to untreated surface. FTIR spectroscopic analysis indicated that polymer chains at the surface undergo certain conformational changes upon solvent treatment. These changes are identified as the restricted motions of C-O-C segments and more intense and specific vibrations of methyl side groups. During solvent treatment, the change in water contact angle and FTIR spectrum of PLLA is well correlated.

  1. Single Cell Force Spectroscopy for Quantification of Cellular Adhesion on Surfaces

    NASA Astrophysics Data System (ADS)

    Christenson, Wayne B.

    Cell adhesion is an important aspect of many biological processes. The atomic force microscope (AFM) has made it possible to quantify the forces involved in cellular adhesion using a technique called single cell force spectroscopy (SCFS). AFM based SCFS offers versatile control over experimental conditions for probing directly the interaction between specific cell types and specific proteins, surfaces, or other cells. Transmembrane integrins are the primary proteins involved in cellular adhesion to the extra cellular matix (ECM). One of the chief integrins involved in the adhesion of leukocyte cells is alpha Mbeta2 (Mac-1). The experiments in this dissertation quantify the adhesion of Mac-1 expressing human embryonic kidney (HEK Mac-1), platelets, and neutrophils cells on substrates with different concentrations of fibrinogen and on fibrin gels and multi-layered fibrinogen coated fibrin gels. It was shown that multi-layered fibrinogen reduces the adhesion force of these cells considerably. A novel method was developed as part of this research combining total internal reflection microscopy (TIRFM) with SCFS allowing for optical microscopy of HEK Mac-1 cells interacting with bovine serum albumin (BSA) coated glass after interacting with multi-layered fibrinogen. HEK Mac-1 cells are able to remove fibrinogen molecules from the multi-layered fibrinogen matrix. An analysis methodology for quantifying the kinetic parameters of integrin-ligand interactions from SCFS experiments is proposed, and the kinetic parameters of the Mac-1 fibrinogen bond are quantified. Additional SCFS experiments quantify the adhesion of macrophages and HEK Mac-1 cells on functionalized glass surfaces and normal glass surfaces. Both cell types show highest adhesion on a novel functionalized glass surface that was prepared to induce macrophage fusion. These experiments demonstrate the versatility of AFM based SCFS, and how it can be applied to address many questions in cellular biology offering

  2. Temporal and mechanistic tracking of cellular uptake dynamics with novel surface fluorophore-bound nanodiamonds.

    PubMed

    Schrand, Amanda M; Lin, Jonathan B; Hens, Suzanne Ciftan; Hussain, Saber M

    2011-02-01

    Nanoparticles (NPs) offer promise for a multitude of biological applications including cellular probes at the bio-interface for targeted delivery of anticancer substances, Raman and fluorescent-based imaging and directed cell growth. Nanodiamonds (NDs), in particular, have several advantages compared to other carbon-based nanomaterials - including a rich surface chemistry useful for chemical conjugation, high biocompatibility with little reactive oxygen species (ROS) generation, physical and chemical stability that affords sterilization, high surface area to volume ratio, transparency and a high index of refraction. The visualization of ND internalization into cells is possible via photoluminescence, which is produced by direct dye conjugation or high energy irradiation that creates nitrogen vacancy centers. Here, we explore the kinetics and mechanisms involved in the intracellular uptake and localization of novel, highly-stable, fluorophore-conjugated NDs. Examination in a neuronal cell line (N2A) shows ND localization to early endosomes and lysosomes with eventual release into the cytoplasm. The addition of endocytosis and exocytosis inhibitors allows for diminished uptake and increased accumulation, respectively, which further corroborates cellular behavior in response to NDs. Ultimately, the ability of the NDs to travel throughout cellular compartments of varying pH without degradation of the surface-conjugated fluorophore or alteration of cell viability over extended periods of time is promising for their use in biomedical applications as stable, biocompatible, fluorescent probes.

  3. Effects of Surface Conditions on Boiling Characteristics,

    DTIC Science & Technology

    contact angle . This model for individual cavities was extended to the entire surface providing an expression for the cumulative site density in terms...water and organics at atmospheric pressure and was incorporated into a unified expression showing explicitly the role of surface geometry and contact angle . (Author)

  4. Characteristics of laser surface melted aluminum alloys.

    PubMed

    Weinman, L S; Kim, C; Tucker, T R; Metzbower, E A

    1978-03-15

    Specimens of Al-Fe 1-4 w/o, 2024 and 6061 Al have been surface melted with a pulsed Nd-glass laser. A TEM and SEM study showed that the dendrite spacings were from 2500 A to 4000 A which corresponds to a cooling rate of over 10(6) degrees C/sec. Melt depths obtained were in the range of 30-100 microm. No significant surface vaporization was observed at energy densities up to 440 J/cm(2). Fracture surfaces of the commerical alloys demonstrated elongated porosity in the melt areas, probably due to internal hydrogen.

  5. Surface charge of trypanosoma cruzi. Binding of cationized ferritin and measurement of cellular electrophoretic mobility.

    PubMed

    De Souza, W; Arguello, C; Martinez-Paloma, A; Trissl, D; Gonzáles-Robles, A; Chiari, E

    1977-08-01

    The surface charge of epimastigote and trypomastigote forms of Trypanosoma cruzi was evaluated by means of binding of cationized ferritin to the cell surface as visualized by electron microscopy, and by direct measurements of the cellular microelectrophoretic mobility (EPM). Epimastigote forms had a mean EPM of -0.52 micrometer-s-1-V-1-cm and were lightly labeled with cationized ferritin. In contrast, bloodstream trypomastigotes had a much higher EPM (-1.14), and the surface was heavily labeled with cationized ferritin. When trypomastigotes from staionary phase cultures were isolated on DEAE cellulose columns, the mean EPM was found to be significantly lower (-0.63), and labeling with cationized ferritin decreased. With a mixed population containing epimastigote, trypomastigote, and intermediate forms, EPM values ranging between -0.70 to -1.14 were found. From these observations we conclude that there is a definite increase in negative surface charge during development from epi- to trypomastigote forms of T. cruzi.

  6. The Development of Surface Roughness and Implications for Cellular Attachment in Biomedical Applications

    NASA Technical Reports Server (NTRS)

    Banks, Bruce; Miller, Sharon; deGroh, Kim; Chan, Amy; Sahota, Mandeep

    2001-01-01

    The application of a microscopic surface texture produced by ion beam sputter texturing to the surfaces of polymer implants has been shown to result in significant increases in cellular attachment compared to smooth surface implants in animal studies. A collaborative program between NASA Glenn Research Center and the Cleveland Clinic Foundation has been established to evaluate the potential for improving osteoblast attachment to surfaces that have been microscopically roughened by atomic oxygen texturing. The range of surface textures that are feasible depends upon both the texturing process and the duration of treatment. To determine whether surface texture saturates or continues to increase with treatment duration, an effort was conducted to examine the development of surface textures produced by various physical and chemical erosion processes. Both experimental tests and computational modeling were performed to explore the growth of surface texture with treatment time. Surface texturing by means of abrasive grit blasting of glass, stainless steel, and polymethylmethacry I ate surfaces was examined to measure the growth in roughness with grit blasting duration by surface profilometry measurements. Laboratory tests and computational modeling was also conducted to examine the development of texture on Aclar(R) (chlorotfifluoroethylene) and Kapton(R) polyimide, respectively. For the atomic oxygen texturing tests of Aclar(R), atomic force microscopy was used to measure the development of texture with atomic oxygen fluence. The results of all the testing and computational modeling support the premise that development of surface roughness obeys Poisson statistics. The results indicate that surface roughness does not saturate but increases as the square root of the treatment time.

  7. Surface decoration by Spirulina polysaccharide enhances the cellular uptake and anticancer efficacy of selenium nanoparticles

    PubMed Central

    Yang, Fang; Tang, Quanming; Zhong, Xueyun; Bai, Yan; Chen, Tianfeng; Zhang, Yibo; Li, Yinghua; Zheng, Wenjie

    2012-01-01

    A simple and solution-phase method for functionalization of selenium nanoparticles (SeNPs) with Spirulina polysaccharides (SPS) has been developed in the present study. The cellular uptake and anticancer activity of SPS-SeNPs were also evaluated. Monodisperse and homogeneous spherical SPS-SeNPs with diameters ranging from 20 nm to 50 nm were achieved under optimized conditions, which were stable in the solution phase for at least 3 months. SPS surface decoration significantly enhanced the cellular uptake and cytotoxicity of SeNPs toward several human cancer cell lines. A375 human melanoma cells were found extremely susceptible to SPS-SeNPs with half maximal (50%) inhibitory concentration value of 7.94 μM. Investigation of the underlying mechanisms revealed that SPS-SeNPs inhibited cancer cell growth through induction of apoptosis, as evidenced by an increase in sub-G1 cell population, deoxyribonucleic acid fragmentation, chromatin condensation, and phosphatidylserine translocation. Results suggest that the strategy to use SPS as a surface decorator could be an effective way to enhance the cellular uptake and anticancer efficacy of nanomaterials. SPS-SeNPs may be a potential candidate for further evaluation as a chemopreventive and chemotherapeutic agent against human cancers. PMID:22359460

  8. Cellular uptake induced biotoxicity of surface-modified CdSe quantum dots

    NASA Astrophysics Data System (ADS)

    Sanwlani, Shilpa; Rawat, Kamla; Pal, Meena; Bohidar, Himadri B.; Verma, Anita Kamra

    2014-05-01

    Cellular uptake of quantum dots (QDs) by cells is of utmost importance for establishing QDs as biostable fluorescent markers that facilitate early diagnosis and detection of cancer. The surface states of QDs are critical to enhance the cellular uptake. Biocompatible CDSe QDs were synthesized using mercaptopropionic acid, amino-ethanethiol HCl, cyltrimethylammonium bromide, dodecyltrimethylammonium bromide, tetrabutylammonium iodide (TBAI), and sodium dodecyl sulfate were functionalized using ligand-exchange method. Cytocompatibility and cellular uptake of QDs were evaluated in human embryonic kidney cells (HEK-29), and breast cancer cells (MCF-7) as reduced cytotoxicity is desirable for biological applications. Approximately, 60 % cytotoxicity was observed in all surface-coated QDs and QD100 in 72 h in both the cell lines, except TBAI that indicated 30 % cytotoxicity in 72 h, and only 10 % in 24 h. Glutathione, the detoxifying molecule, is detrimental for understanding the oxidative stress of the cell. The QDs showed enhanced Glutathione- S-transferase (GST) activity in the MCF-7 cell line. In HEK, CdSe per se was also able to induce a high level of GST. QDs toxicity may either be related to the induction of reactive oxygen species or the direct release of metal ions. Optimization of QDs in terms of quantification and DNA damage is imperative for realistic biological applications.

  9. Cellular Homeostasis and Antioxidant Response in Epithelial HT29 Cells on Titania Nanotube Arrays Surface

    PubMed Central

    Hazan, Roshasnorlyza; Mat, Ishak

    2017-01-01

    Cell growth and proliferative activities on titania nanotube arrays (TNA) have raised alerts on genotoxicity risk. Present toxicogenomic approach focused on epithelial HT29 cells with TNA surface. Fledgling cell-TNA interaction has triggered G0/G1 cell cycle arrests and initiates DNA damage surveillance checkpoint, which possibly indicated the cellular stress stimuli. A profound gene regulation was observed to be involved in cellular growth and survival signals such as p53 and AKT expressions. Interestingly, the activation of redox regulator pathways (antioxidant defense) was observed through the cascade interactions of GADD45, MYC, CHECK1, and ATR genes. These mechanisms furnish to protect DNA during cellular division from an oxidative challenge, set in motion with XRRC5 and RAD50 genes for DNA damage and repair activities. The cell fate decision on TNA-nanoenvironment has been reported to possibly regulate proliferative activities via expression of p27 and BCL2 tumor suppressor proteins, cogent with SKP2 and BCL2 oncogenic proteins suppression. Findings suggested that epithelial HT29 cells on the surface of TNA may have a positive regulation via cell-homeostasis mechanisms: a careful circadian orchestration between cell proliferation, survival, and death. This nanomolecular knowledge could be beneficial for advanced medical applications such as in nanomedicine and nanotherapeutics. PMID:28337249

  10. Mapping cellular hierarchy by single cell analysis of the cell surface repertoire

    PubMed Central

    Guo, Guoji; Luc, Sidinh; Marco, Eugenio; Lin, Ta-Wei; Peng, Cong; Kerenyi, Marc A.; Beyaz, Semir; Kim, Woojin; Xu, Jian; Das, Partha Pratim; Neff, Tobias; Zou, Keyong; Yuan, Guo-Cheng; Orkin, Stuart H.

    2013-01-01

    SUMMARY Stem cell differentiation pathways are most often studied at the population level, whereas critical decisions are executed at the level of single cells. We have established a highly multiplexed, quantitative PCR assay to profile in an unbiased manner a panel of all commonly used cell surface markers (280 genes) from individual cells. With this method we analyzed over 1500 single cells throughout the mouse hematopoietic system, and illustrate its utility for revealing important biological insights. The comprehensive single cell dataset permits mapping of the mouse hematopoietic stem cell (HSC) differentiation hierarchy by computational lineage progression analysis. Further profiling of 180 intracellular regulators enabled construction of a genetic network to assign the earliest differentiation event during hematopoietic lineage specification. Analysis of acute myeloid leukemia elicited by MLL-AF9 uncovered a distinct cellular hierarchy containing two independent self-renewing lineages with different clonal activities. The strategy has broad applicability in other cellular systems. PMID:24035353

  11. Surface Charge Convertible and Biodegradable Synthetic Zwitterionic Nanoparticles for Enhancing Cellular Drug Uptake.

    PubMed

    Wu, Luyan; Ni, Caihua; Zhang, Liping; Shi, Gang; Bai, Xue; Zhou, Yamin; He, Fei

    2016-03-01

    To enhance drug cellular uptake, a biodegradable terpolymer is synthesized using taurine, N,N-Bis (acryloyl) cystamine, and dodecylamine as raw materials by Michael addition terpolymerization. The terpolymer is transformed to zwitterionic nanoparticles (NPs) through self-assembly. The surface charge of the NPs is convertible from negative at pH 7.4 to positive at pH 6.5, which endows the NPs' excellent nonfouling feature in bloodstream and effective uptake in tumor cells. The NPs display varied morphologies from solid micelles to polymersomes and nanorods depending on molar ratios of the structural units involved. The NPs can be biodegraded in l-glutathione (GSH) solution due to the split of disulfide bonds in main chains of the terpolymers. The NPs demonstrate good pH/reducing responsiveness in drug delivery and can be potentially used as anticancer drug vehicles for enhancement of cellular uptake of anticancer drug.

  12. Characteristics of Middle School Students Learning Actions in Outdoor Mathematical Activities with the Cellular Phone

    ERIC Educational Resources Information Center

    Daher, Wajeeh; Baya'a, Nimer

    2012-01-01

    Learning in the cellular phone environment enables utilizing the multiple functions of the cellular phone, such as mobility, availability, interactivity, verbal and voice communication, taking pictures or recording audio and video, measuring time and transferring information. These functions together with mathematics-designated cellular phone…

  13. On the Interaction between Marine Boundary Layer Cellular Cloudiness and Surface Heat Fluxes

    SciTech Connect

    Kazil, J.; Feingold, G.; Wang, Hailong; Yamaguchi, T.

    2014-01-02

    The interaction between marine boundary layer cellular cloudiness and surface uxes of sensible and latent heat is investigated. The investigation focuses on the non-precipitating closed-cell state and the precipitating open-cell state at low geostrophic wind speed. The Advanced Research WRF model is used to conduct cloud-system-resolving simulations with interactive surface fluxes of sensible heat, latent heat, and of sea salt aerosol, and with a detailed representation of the interaction between aerosol particles and clouds. The mechanisms responsible for the temporal evolution and spatial distribution of the surface heat fluxes in the closed- and open-cell state are investigated and explained. It is found that the horizontal spatial structure of the closed-cell state determines, by entrainment of dry free tropospheric air, the spatial distribution of surface air temperature and water vapor, and, to a lesser degree, of the surface sensible and latent heat flux. The synchronized dynamics of the the open-cell state drives oscillations in surface air temperature, water vapor, and in the surface fluxes of sensible and latent heat, and of sea salt aerosol. Open-cell cloud formation, cloud optical depth and liquid water path, and cloud and rain water path are identified as good predictors of the spatial distribution of surface air temperature and sensible heat flux, but not of surface water vapor and latent heat flux. It is shown that by enhancing the surface sensible heat flux, the open-cell state creates conditions by which it is maintained. While the open-cell state under consideration is not depleted in aerosol, and is insensitive to variations in sea-salt fluxes, it also enhances the sea-salt flux relative to the closed-cell state. In aerosol-depleted conditions, this enhancement may replenish the aerosol needed for cloud formation, and hence contribute to the perpetuation of the open-cell state as well. Spatial homogenization of the surface fluxes is found to have

  14. Light-Scattering Characteristics of Optical Surfaces

    DTIC Science & Technology

    1975-01-01

    UNCLASSIFIED Psd) Accession For NTIS GRA&I DTIC TAB Unannounced d ] Justificatio By - Distributon/_ Availability Codes JAvail and/or_ CHAPTER 1...rejection systems, evaluation of machined metal mirrors for high- energy laser applications , laser-radar backscatter signature programs, and a host of...other applications requiring extensive scattering data. If the scattering mechanism were completely understood, surface prepa- ration techniques or

  15. The plasma membrane flattens out to fuel cell surface growth during Drosophila cellularization

    PubMed Central

    Figard, Lauren; Xu, Heng; Garcia, Hernan G.; Golding, Ido; Sokac, Anna Marie

    2014-01-01

    Summary Cell shape change demands cell surface growth, but how growth is fueled and choreographed is still debated. Here, we use cellularization, the first complete cytokinetic event in Drosophila embryos, to show that cleavage furrow ingression is kinetically coupled to the loss of surface microvilli. We modulate furrow kinetics with RNAi against the Rho1-GTPase regulator slam, and show that furrow ingression controls the rate of microvillar depletion. Finally, we directly track microvillar membrane and see it move along the cell surface and into ingressing furrows, independent of endocytosis. Together, our results demonstrate that the kinetics of the ingressing furrow regulate the utilization of a microvillar membrane reservoir. Since the membrane of the furrow and microvilli are contiguous, we suggest that ingression drives unfolding of the microvilli and incorporation of microvillar membrane into the furrow. We conclude that plasma membrane folding/unfolding can contribute to the cell shape changes that promote embryonic morphogenesis. PMID:24316147

  16. Cellular membrane enrichment of self-assembling D-peptides for cell surface engineering.

    PubMed

    Wang, Huaimin; Wang, Youzhi; Han, Aitian; Cai, Yanbin; Xiao, Nannan; Wang, Ling; Ding, Dan; Yang, Zhimou

    2014-06-25

    We occasionally found that several self-assembling peptides containing D-amino acids would be preferentially enriched in cellular membranes at self-assembled stages while distributed evenly in the cytoplasma of cells at unassembled stages. Self-assembling peptides containing only Lamino acids distributed evenly in cytoplasma of cells at both self-assembled and unassembled stages. The self-assembling peptides containing D-amino acids could therefore be applied for engineering cell surface with peptides. More importantly, by integrating a protein binding peptide (a PDZ domain binding hexapeptide of WRESAI) with the self-assembling peptide containing D-amino acids, protein could also be introduced to the cell surface. This study not only provided a novel approach to engineer cell surface, but also highlighted the unusual properties and potential applications of self-assembling peptides containing D-amino acids in regenerative medicine, drug delivery, and tissue engineering.

  17. Upper surface blowing aerodynamic and acoustic characteristics

    NASA Technical Reports Server (NTRS)

    Ryle, D. M., Jr.; Braden, J. A.; Gibson, J. S.

    1977-01-01

    Aerodynamic performance at cruise, and noise effects due to variations in nacelle and wing geometry and mode of operation are studied using small aircraft models that simulate upper surface blowing (USB). At cruise speeds ranging from Mach .50 to Mach .82, the key determinants of drag/thrust penalties are found to be nozzle aspect ratio, boattailing angle, and chordwise position; number of nacelles; and streamlined versus symmetric configuration. Recommendations are made for obtaining favorable cruise configurations. The acoustic studies, which concentrate on the noise created by the jet exhaust flow and its interaction with wing and flap surfaces, isolate several important sources of USB noise, including nozzle shape, exit velocity, and impingement angle; flow pathlength; and flap angle and radius of curvature. Suggestions for lessening noise due to trailing edge flow velocity, flow pathlength, and flow spreading are given, though compromises between some design options may be necessary.

  18. Petrologic Characteristics of the Lunar Surface

    NASA Astrophysics Data System (ADS)

    Wang, Xianmin; Pedrycz, Witold

    2015-11-01

    Petrologic analysis of the lunar surface is critical for determining lunar formation and evolution. Here, we report the first global petrologic map that includes the five most important lunar lithological units: the Ferroan Anorthositic (FAN) Unit, the Magnesian Suite (MS) Unit, the Alkali Suite (AS) Unit, the KREEP Basalt (KB) Unit and the Mare Basalt (MB) Unit. Based on the petrologic map and focusing on four long-debated and important issues related to lunar formation and evolution, we draw the following conclusions from the new insights into the global distribution of the five petrologic units: (1) there may be no petrogenetic relationship between MS rocks and KB; (2) there may be no petrogenetic link between MS and AS rocks; (3) the exposure of the KREEP component on the lunar surface is likely not a result of MB volcanism but is instead mainly associated with the combined action of plutonic intrusion, KREEP volcanism and celestial collision; (4) the impact size of the South Pole-Aitken basin is constrained, i.e., the basin has been excavated through the whole crust to exhume a vast majority of lower-crustal material and a very limited mantle components to the lunar surface.

  19. Petrologic Characteristics of the Lunar Surface

    PubMed Central

    Wang, Xianmin; Pedrycz, Witold

    2015-01-01

    Petrologic analysis of the lunar surface is critical for determining lunar formation and evolution. Here, we report the first global petrologic map that includes the five most important lunar lithological units: the Ferroan Anorthositic (FAN) Unit, the Magnesian Suite (MS) Unit, the Alkali Suite (AS) Unit, the KREEP Basalt (KB) Unit and the Mare Basalt (MB) Unit. Based on the petrologic map and focusing on four long-debated and important issues related to lunar formation and evolution, we draw the following conclusions from the new insights into the global distribution of the five petrologic units: (1) there may be no petrogenetic relationship between MS rocks and KB; (2) there may be no petrogenetic link between MS and AS rocks; (3) the exposure of the KREEP component on the lunar surface is likely not a result of MB volcanism but is instead mainly associated with the combined action of plutonic intrusion, KREEP volcanism and celestial collision; (4) the impact size of the South Pole-Aitken basin is constrained, i.e., the basin has been excavated through the whole crust to exhume a vast majority of lower-crustal material and a very limited mantle components to the lunar surface. PMID:26611148

  20. Petrologic Characteristics of the Lunar Surface.

    PubMed

    Wang, Xianmin; Pedrycz, Witold

    2015-11-27

    Petrologic analysis of the lunar surface is critical for determining lunar formation and evolution. Here, we report the first global petrologic map that includes the five most important lunar lithological units: the Ferroan Anorthositic (FAN) Unit, the Magnesian Suite (MS) Unit, the Alkali Suite (AS) Unit, the KREEP Basalt (KB) Unit and the Mare Basalt (MB) Unit. Based on the petrologic map and focusing on four long-debated and important issues related to lunar formation and evolution, we draw the following conclusions from the new insights into the global distribution of the five petrologic units: (1) there may be no petrogenetic relationship between MS rocks and KB; (2) there may be no petrogenetic link between MS and AS rocks; (3) the exposure of the KREEP component on the lunar surface is likely not a result of MB volcanism but is instead mainly associated with the combined action of plutonic intrusion, KREEP volcanism and celestial collision; (4) the impact size of the South Pole-Aitken basin is constrained, i.e., the basin has been excavated through the whole crust to exhume a vast majority of lower-crustal material and a very limited mantle components to the lunar surface.

  1. Adsorption of glycosaminoglycans to the cell surface is responsible for cellular donnan effects.

    PubMed

    Hagenfeld, Daniel; Kathagen, Nadine; Prehm, Peter

    2014-07-01

    In previous publications, we showed that extracellular glycosaminoglycans reduced the membrane potential, caused cell blebbing and swelling and decreased the intracellular pH independently of cell surface receptors. These phenomena were explained by Donnan effects. The effects were so large that they could not be attributed to glycosaminoglycans in solution. Therefore, we tested the hypothesis that glycosaminoglycans were concentrated on the cell membrane and analysed the mechanism of adsorption by fluorescent hyaluronan, chondroitin sulphate and heparin. The influence of the CD44 receptor was evaluated by comparing CD44 expressing human fibroblasts with CD44 deficient HEK cells. Higher amounts of glycosaminoglycans adsorbed to fibroblasts than to HEK cells. When the membrane potential was annihilated by substituting NaCl by KCl in the medium, adsorption was reduced and intracellular pH decrease was abolished. To eliminate other cellular interfering factors, potential-dependent adsorption was demonstrated for hyaluronan which adsorbed to inert gold foils in physiological salt concentrations at pH 7.2 and surface potentials up to 120 mV. From these results, we conclude that large cellular Donnan effects of glycosaminoglycans results from receptor mediated, hydrophobic and ionic adsorption to cell surfaces.

  2. Cellular interaction influenced by surface modification strategies of gelatin-based nanoparticles.

    PubMed

    Tse, Wai Hei; Gyenis, Laszlo; Litchfield, David W; Zhang, Jin

    2017-02-01

    Theranostic applications of gelatin nanospheres require two major components, a method of detection and good biocompatibility. We characterized the response of UTA-6 human osteosarcoma cells to the introduction of functionalized 90 bloom-based gelatin nanospheres (158 ± 49 nm) modified with three elements in different order: (a) hybridization with cadmium-based quantum dots for optical detection, (b) bioconjugation with anti-human IgG FAB (anti-IgG) for cell targeting, with/without (c) capping with polyethylene glycol on the surface for enhanced biocompatibility. A one-pot process is developed for incorporating quantum dots and antibody with gelatin nanospheres. Path A of modifying gelatin nanospheres with quantum dots first followed by anti-IgG resulted in a significantly greater cellular viability than Path B with anti-IgG first followed by quantum dots. Capping with polyethylene glycol as the final step in modification yielded significantly opposing results with decreases in Path A and increases in Path B. Three-dimensional z-stacking fluorescent images of hybrid gelatin nanospheres with anti-IgG is observed to have an increase in cellular association. The observed results suggest the modification order for building hybrid nanospheres may have an impact on cellular response.

  3. 3D surface reconstruction and visualization of the Drosophila wing imaginal disc at cellular resolution

    NASA Astrophysics Data System (ADS)

    Bai, Linge; Widmann, Thomas; Jülicher, Frank; Dahmann, Christian; Breen, David

    2013-01-01

    Quantifying and visualizing the shape of developing biological tissues provide information about the morphogenetic processes in multicellular organisms. The size and shape of biological tissues depend on the number, size, shape, and arrangement of the constituting cells. To better understand the mechanisms that guide tissues into their final shape, it is important to investigate the cellular arrangement within tissues. Here we present a data processing pipeline to generate 3D volumetric surface models of epithelial tissues, as well as geometric descriptions of the tissues' apical cell cross-sections. The data processing pipeline includes image acquisition, editing, processing and analysis, 2D cell mesh generation, 3D contourbased surface reconstruction, cell mesh projection, followed by geometric calculations and color-based visualization of morphological parameters. In their first utilization we have applied these procedures to construct a 3D volumetric surface model at cellular resolution of the wing imaginal disc of Drosophila melanogaster. The ultimate goal of the reported effort is to produce tools for the creation of detailed 3D geometric models of the individual cells in epithelial tissues. To date, 3D volumetric surface models of the whole wing imaginal disc have been created, and the apicolateral cell boundaries have been identified, allowing for the calculation and visualization of cell parameters, e.g. apical cross-sectional area of cells. The calculation and visualization of morphological parameters show position-dependent patterns of cell shape in the wing imaginal disc. Our procedures should offer a general data processing pipeline for the construction of 3D volumetric surface models of a wide variety of epithelial tissues.

  4. Spatial characteristics of ocean surface waves

    NASA Astrophysics Data System (ADS)

    Gemmrich, Johannes; Thomson, Jim; Rogers, W. Erick; Pleskachevsky, Andrey; Lehner, Susanne

    2016-08-01

    The spatial variability of open ocean wave fields on scales of O (10km) is assessed from four different data sources: TerraSAR-X SAR imagery, four drifting SWIFT buoys, a moored waverider buoy, and WAVEWATCH III Ⓡ model runs. Two examples from the open north-east Pacific, comprising of a pure wind sea and a mixed sea with swell, are given. Wave parameters attained from observations have a natural variability, which decreases with increasing record length or acquisition area. The retrieval of dominant wave scales from point observations and model output are inherently different to dominant scales retrieved from spatial observations. This can lead to significant differences in the dominant steepness associated with a given wave field. These uncertainties have to be taken into account when models are assessed against observations or when new wave retrieval algorithms from spatial or temporal data are tested. However, there is evidence of abrupt changes in wave field characteristics that are larger than the expected methodological uncertainties.

  5. Surface Characteristics of Titanium during ECM Process for Biomedical Applications

    SciTech Connect

    Dhobe, Shirish D.; Doloi, B.; Bhattacharyya, B.

    2011-01-17

    Electrochemical machining is described as the controlled removal of metal by anodic dissolution of the workpiece in electrolyte cell. Titanium is extensively used in aerospace, defence, biomedical applications. The human response to implanted titanium parts strongly related to the implant surface conditions. The aim of this paper is to present experimental investigation on electrochemically machined surface characteristics acquired on titanium, utilizing developed cross flow electrolyte system. It is observed that applied voltage and electrolyte flow rate are the some of the persuading parameter to attain desired surface characteristics on machined surface. Attempt has made to develop surface along with self-generated oxide layer, which facilitates in improving the corrosion and chemical resistance of titanium implant in biomedical application. The surface roughness of oxide layered machined surface obtained within 2.4 {mu}m to 2.93 {mu}m, which is within acceptable value for functional attachment between bone and implant.

  6. Biomaterial design for specific cellular interactions: Role of surface functionalization and geometric features

    NASA Astrophysics Data System (ADS)

    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. Skin characteristics by laser generated surface waves.

    PubMed

    Huang, Zhihong; L'Etang, Adèle

    2009-01-01

    This paper discusses a study into the suitability of using laser generated surface acoustic waves for the characterisation of skin properties without causing any damage to the skin thermally or by mechanical disruption. Using commercial Finite Element Code ANSYS, the effects of laser wavelength, laser beam radius and laser rise time on generation of laser generated ultrasonic waves in a 3-layered elastic isotropic model of human skin were studied. The FE model is an example of a sequential coupled field analysis where the thermal and mechanical analyses are treated separately. The heating of the skin model due to the short laser pulse is simulated by a dynamic thermal analysis with the laser pulse modeled as volumetric heat generation and the results from this analysis subsequently applied as a load in the mechanical analysis where the out-of-plane displacement histories are analyzed. The technique described in this paper also involves measuring the propagation velocity of SAWs, which are directly related to the material properties, and thickness of layers, this is done over a wide frequency range in order to obtain maximum information regarding the material under test.

  8. Wetting characteristics of 3-dimensional nanostructured fractal surfaces

    NASA Astrophysics Data System (ADS)

    Davis, Ethan; Liu, Ying; Jiang, Lijia; Lu, Yongfeng; Ndao, Sidy

    2017-01-01

    This article reports the fabrication and wetting characteristics of 3-dimensional nanostructured fractal surfaces (3DNFS). Three distinct 3DNFS surfaces, namely cubic, Romanesco broccoli, and sphereflake were fabricated using two-photon direct laser writing. Contact angle measurements were performed on the multiscale fractal surfaces to characterize their wetting properties. Average contact angles ranged from 66.8° for the smooth control surface to 0° for one of the fractal surfaces. The change in wetting behavior was attributed to modification of the interfacial surface properties due to the inclusion of 3-dimensional hierarchical fractal nanostructures. However, this behavior does not exactly obey existing surface wetting models in the literature. Potential applications for these types of surfaces in physical and biological sciences are also discussed.

  9. Nano-fabrication of cellular force sensors and surface coatings via dendritic solidification

    NASA Astrophysics Data System (ADS)

    Paneru, Govind

    Directed electrochemical nanowire assembly (DENA) is a method for fabricating nano-structured materials via electrochemical dendritic solidification. This thesis presents two new applications of nano-structured materials that are fabricated via the DENA methodology: cellular force sensors to probe adhesive sites on living cells and single-crystalline metallic dendrites as surface coating materials. Fast migrating cells like D. discoideum, leukocytes, and breast cancer cells migrate by attachment and detachment of discrete adhesive contacts, known as actin foci, to the substrate where the cell transmits traction forces. Despite their importance in migration, the physics by which actin foci bind and release substrates is poorly understood. This gap is largely due to the compositional complexity of actin foci in living cells and to a lack of technique for directly probing these sub-cellular structures. Recent theoretical work predicts these adhesive structures to depend on the density of adhesion receptors in the contact sites, the receptor-substrate potential, and cell-medium surface tension. This thesis describes the fabrication of sub-microscopic force sensors composed of poly(3,4-ethylene dioxythiophene) fibers that can interface directly with sub-cellular targets such as actin foci. The spring constants of these fibers are in the range of 0.07-430 nN mum -1. These fibers were used to characterize the strength and lifetime of adhesion between the single adhesive contacts of D. discoideum cells and the fibers, finding an average force of 3.1 +/- 2.7 nN and lifetime of 23.4 +/- 18.5 s. This capability is significant because direct measurement of these properties will be necessary to measure the cell-medium surface tension and to characterize the receptor-substrate potential in the next (future) stage of this project. The fabrication of smart materials that are capable of the high dynamic range structural reconfiguration would lead to their use to confer hydrophobic

  10. Surface charge and cellular processing of covalently functionalized multiwall carbon nanotubes determine pulmonary toxicity.

    PubMed

    Li, Ruibin; Wang, Xiang; Ji, Zhaoxia; Sun, Bingbing; Zhang, Haiyuan; Chang, Chong Hyun; Lin, Sijie; Meng, Huan; Liao, Yu-Pei; Wang, Meiying; Li, Zongxi; Hwang, Angela A; Song, Tze-Bin; Xu, Run; Yang, Yang; Zink, Jeffrey I; Nel, André E; Xia, Tian

    2013-03-26

    Functionalized carbon nanotubes (f-CNTs) are being produced in increased volume because of the ease of dispersion and maintenance of the pristine material physicochemical properties when used in composite materials as well as for other commercial applications. However, the potential adverse effects of f-CNTs have not been quantitatively or systematically explored. In this study, we used a library of covalently functionalized multiwall carbon nanotubes (f-MWCNTs), established from the same starting material, to assess the impact of surface charge in a predictive toxicological model that relates the tubes' pro-inflammatory and pro-fibrogenic effects at cellular level to the development of pulmonary fibrosis. Carboxylate (COOH), polyethylene glycol (PEG), amine (NH2), sidewall amine (sw-NH2), and polyetherimide (PEI)-modified MWCNTs were successfully established from raw or as-prepared (AP-) MWCNTs and comprehensively characterized by TEM, XPS, FTIR, and DLS to obtain information about morphology, length, degree of functionalization, hydrodynamic size, and surface charge. Cellular screening in BEAS-2B and THP-1 cells showed that, compared to AP-MWCNTs, anionic functionalization (COOH and PEG) decreased the production of pro-fibrogenic cytokines and growth factors (including IL-1β, TGF-β1, and PDGF-AA), while neutral and weak cationic functionalization (NH2 and sw-NH2) showed intermediary effects. In contrast, the strongly cationic PEI-functionalized tubes induced robust biological effects. These differences could be attributed to differences in cellular uptake and NLRP3 inflammasome activation, which depends on the propensity toward lysosomal damage and cathepsin B release in macrophages. Moreover, the in vitro hazard ranking was validated by the pro-fibrogenic potential of the tubes in vivo. Compared to pristine MWCNTs, strong cationic PEI-MWCNTs induced significant lung fibrosis, while carboxylation significantly decreased the extent of pulmonary fibrosis. These

  11. Polyaspartamide derivative nanoparticles with tunable surface charge achieve highly efficient cellular uptake and low cytotoxicity.

    PubMed

    Xu, Min; Zhao, Yuefang; Feng, Min

    2012-08-07

    Cationic nanocarrier mediated intracellular therapeutic agent delivery acts as a double-edged sword: the carriers promote cellular uptake, but interact nonspecifically and strongly with negatively charged endogenic proteins and cell membranes, which results in aggregates and high cytotoxicity. The present study was aimed at exploring zwitterionic polyaspartamide derivative nanoparticles for efficient intracellular delivery with low cytotoxicity. Poly(aspartic acid) partially grafted tetraethylenepentamine (PASP-pg-TEPA) with different isoelectric points (IEPs) was synthesized. The PASP-pg-TEPA formed zwitterionic nanoparticles with an irregular core and a well-defined shell structure in aqueous medium. Their particle size decreased from about 300 to 80 nm with an increase of the IEP from 7.5 to 9.1. The surface charge of the PASP-pg-TEPA nanoparticles could be tuned from positive to negative with a change of the pH of the medium. The nanoparticles with an IEP above 8.5 exhibited good stability under simulated physiological conditions. It was noted that the zwitterionic PASP-pg-TEPA nanoparticles displayed highly efficient cellular uptake in HeLa cells (approximately 99%) in serum-containing medium and did not adversely affect the cell viability at concentrations up to 1 mg/mL. Furthermore, thermodynamic analysis using isothermal titration calorimetry provided direct evidence that these zwitterionic nanoparticles had low binding affinities for serum protein. Therefore, the zwitterionic PASP-pg-TEPA nanoparticles could overcome limitations of cationic nanocarriers and achieve efficient intracellular delivery with low cytotoxicity.

  12. Titanium oral implants: surface characteristics, interface biology and clinical outcome

    PubMed Central

    Palmquist, Anders; Omar, Omar M.; Esposito, Marco; Lausmaa, Jukka; Thomsen, Peter

    2010-01-01

    Bone-anchored titanium implants have revolutionized oral healthcare. Surface properties of oral titanium implants play decisive roles for molecular interactions, cellular response and bone regeneration. Nevertheless, the role of specific surface properties, such as chemical and phase composition and nanoscale features, for the biological in vivo performance remains to be established. Partly, this is due to limited transfer of state-of-the-art preparation techniques to complex three-dimensional geometries, analytical tools and access to minute, intact interfacial layers. As judged by the available results of a few randomized clinical trials, there is no evidence that any particular type of oral implant has superior long-term success. Important insights into the recruitment of mesenchymal stem cells, cell–cell communication at the interface and high-resolution imaging of the interface between the surface oxide and the biological host are prerequisites for the understanding of the mechanisms of osseointegration. Strategies for development of the next generation of material surface modifications for compromised tissue are likely to include time and functionally programmed properties, pharmacological modulation and incorporation of cellular components. PMID:20591849

  13. The surface state of hematite and its wetting characteristics.

    PubMed

    Shrimali, Kaustubh; Jin, Jiaqi; Hassas, Behzad Vaziri; Wang, Xuming; Miller, Jan D

    2016-09-01

    Apart from being a resource for iron/steel production, the iron oxide minerals, goethite and hematite, are used in the paint, cosmetics, and other industries as pigments. Surface characteristics of these minerals have been studied extensively both in resource recovery by flotation and in the preparation of colloidal dispersions. In this current research, the wetting characteristics of goethite (FeOOH) and hematite (Fe2O3) have been analyzed by means of contact angle, bubble attachment time, and Atomic Force Microscopy (AFM) measurements as well as by Molecular Dynamics Simulation (MDS). Goethite is naturally hydroxylated and wetted by water at all pH values. In contrast, the anhydrous hematite surface (001) was found to be slightly hydrophobic at natural pH values with a contact angle of about 50°. At alkaline pH hydroxylation of the hematite surface occurs rapidly and the hematite becomes hydrophilic. The wetting characteristics of the hematite surface then vary between the hydrophobic anhydrous hematite and the completely hydrophilic hydroxylated hematite, similar to goethite. The hydrophobicity can be restored by heating of the hydroxylated hematite surface at 60°C. The hydrophobic character of the anhydrous hematite (001) surface is confirmed by MDS which also reveals that after hydrolysis the hematite (001) surface can be wetted by water, similar to the goethite (001) surface.

  14. Spatiotemporal control over molecular delivery and cellular encapsulation from electropolymerized micro- and nanopatterned surfaces

    PubMed Central

    Stern, Eric; Jay, Steven M.; Demento, Stacey L.; Murelli, Ryan P.; Reed, Mark A.; Malinski, Tadeusz; Spiegel, David A.; Mooney, David J.; Fahmy, Tarek M.

    2010-01-01

    Bioactive, patterned micro- and nanoscale surfaces that can be spatially engineered for three-dimensional ligand presentation and sustained release of signaling molecules represent a critical advance for the development of next-generation diagnostic and therapeutic devices. Lithography is ideally suited to patterning such surfaces due to its precise, easily scalable, high-throughput nature; however, to date polymers patterned by these techniques have not demonstrated the capacity for sustained release of bioactive agents. We demonstrate here a class of lithographically-defined, electropolymerized polymers with monodisperse micro- and nanopatterned features capable of sustained release of bioactive drugs and proteins. We show that precise control can be achieved over the loading capacity and release rates of encapsulated agents and illustrate this aspect using a fabricated surface releasing a model antigen (ovalbumin) and a cytokine (interleukin-2) for induction of a specific immune response. We further demonstrate the ability of this technique to enable three-dimensional control over cellular encapsulation. The efficacy of the described approach is buttressed by its simplicity, versatility, and reproducibility, rendering it ideally suited for biomaterials engineering. PMID:20445826

  15. Enhancing Cellular Uptake and Doxorubicin Delivery of Mesoporous Silica Nanoparticles via Surface Functionalization: Effects of Serum.

    PubMed

    Shahabi, Shakiba; Döscher, Svea; Bollhorst, Tobias; Treccani, Laura; Maas, Michael; Dringen, Ralf; Rezwan, Kurosch

    2015-12-09

    In this study, we demonstrate how functional groups on the surface of mesoporous silica nanoparticles (MSNPs) can influence the encapsulation and release of the anticancer drug doxorubicin, as well as cancer cell response in the absence or presence of serum proteins. To this end, we synthesized four differently functionalized MSNPs with amine, sulfonate, polyethylene glycol, or polyethylene imine functional surface groups, as well as one type of antibody-conjugated MSNP for specific cellular targeting, and we characterized these MSNPs regarding their physicochemical properties, colloidal stability in physiological media, and uptake and release of doxorubicin in vitro. Then, the MSNPs were investigated for their cytotoxic potential on cancer cells. Cationic MSNPs could not be loaded with doxorubicin and did therefore not show any cytotoxic and antiproliferative potential on osteosarcoma cells, although they were efficiently taken up into the cells in the presence or absence of serum. In contrast, substantial amounts of doxorubicin were loaded into negatively charged and unfunctionalized MSNPs. Especially, sulfonate-functionalized doxorubicin-loaded MSNPs were efficiently taken up into the cells in the presence of serum and showed an accelerated toxic and antiproliferative potential compared to unfunctionalized MSNPs, antibody-conjugated MSNPs, and even free doxorubicin. These findings stress the high importance of the surface charge as well as of the protein corona for designing and applying nanoparticles for targeted drug delivery.

  16. The relationship between cellular adhesion and surface roughness for polyurethane modified by microwave plasma radiation.

    PubMed

    Keshel, Saeed Heidari; Azhdadi, S Neda Kh; Asefnejad, Azadeh; Asefnezhad, Azadeh; Sadraeian, Mohammad; Montazeri, Mohamad; Biazar, Esmaeil

    2011-01-01

    Surface modification of medical polymers is carried out to improve biocompatibility. In this study, conventional polyurethane was exposed to microwave plasma treatment with oxygen and argon gases for 30 seconds and 60 seconds. Attenuated total reflection Fourier transform infrared spectra investigations of irradiated samples indicated the presence of functional groups. Atomic force microscope images of samples irradiated with inert and active gases indicated the nanometric topography of the sample surfaces. Samples irradiated by oxygen plasma indicated high roughness compared with those irradiated by inert plasma for the different lengths of time. In addition, surface roughness increased with time, which can be due to a reduction of contact angle of samples irradiated by oxygen plasma. Contact angle analysis indicated a reduction in samples irradiated with both types of plasma. However, samples irradiated with oxygen plasma indicated lower contact angle compared with those irradiated by argon plasma. Cellular investigations with unrestricted somatic stem cells showed better adhesion, cell growth, and proliferation among samples radiated by oxygen plasma for longer than for normal samples.

  17. Effects of surface chemistry on the optical properties and cellular interaction of lanthanide-based nanoparticles

    NASA Astrophysics Data System (ADS)

    Pedraza, Francisco J.; Avalos, Julio C.; Mimun, Lawrence C.; Yust, Brian G.; Tsin, Andrew; Sardar, Dhiraj K.

    2015-03-01

    Fluorescent nanoparticles (NPs) such as KYb2F7:Tm3+ potential in biomedical applications due to their ability to absorb and emit within the biological window, where near infrared light is less attenuated by soft tissue. This results in less tissue damage and deeper tissue penetration making it a viable candidate in biological imaging. Another big factor in determining their ability to perform in a biological setting is the surface chemistry. Biocompatible coatings, including polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), pluronic and folic acid are commonly used because they pose several advantages such as ease of functionalization, better dispersion, and higher cellular uptake. To study the effects of the NP surface chemistry, KYb2F7:Tm3+ a solvothermal method using PEG, PVP, pluronic acid, and folic acid as a capping agent, followed by thorough optical characterizations. Optical changes were thoroughly studied and compared using absorption, emission, and quantum yield data. Cell viability was obtained by treating Rhesus Monkey Retinal Endothelial cells (RhREC) with KYb2F7:Tm3+ and counting viable cells following a 24 hour uptake period. The work presented will compare the optical properties and toxicity dependency on the surface chemistry on KYb2F7:Tm3+. The results will also indicate that KYb2F7:Tm3+ nanoparticles are viable candidates for various biomedical applications.

  18. Electronic characteristics of 'real' CdS surfaces.

    NASA Technical Reports Server (NTRS)

    Lagowski, J.; Balestra, C. L.; Gatos, H. C.

    1972-01-01

    Photovoltage spectroscopy (including photovoltage inversion and photovoltage quenching) was used to determine the electronic characteristics of real (basal and prismatic) surfaces of CdS. In room atmosphere, surface states with the following positions were found in the cadmium surfaces: Ec - Et equal to 0.05, 0.4, and 0.8 eV, and Ev - Et equal to 0.83 eV. The same surface states were present in the sulfur surfaces, with the exception of those at Ec - Et equal to 0.4 eV. In the prismatic and unetched basal surfaces, states at Ec - Et equal to 1.1 eV were found in addition to all of those found on the cadmium surfaces.

  19. Surface properties of lipoplexes modified with mannosylerythritol lipid-a and tween 80 and their cellular association.

    PubMed

    Ding, Wuxiao; Hattori, Yoshiyuki; Qi, Xianrong; Kitamoto, Dai; Maitani, Yoshie

    2009-02-01

    The surface properties of cationic liposomes and lipoplexes largely determine the cellular association and gene transfection efficiency. In this study, we measured the surface properties, such as zeta potentials, surface pH and hydration levels of MHAPC- and OH-Chol-lipoplexes and their cellular association, without and with the modification of biosurfactant mannosylerythritol lipid-A (MEL-A) or Tween 80 (MHAPC=N,N-methyl hydroxyethyl aminopropane carbamoyl cholesterol; OH-Chol=cholesteryl-3beta-carboxyamindoethylene-N-hydroxyethylamine). Compared to OH-Chol-lipoplexes, the higher cellular association of MHAPC-lipoplexes correlated with the significantly higher zeta potentials, lower surface pH levels and "drier" surface, as evaluated by the generalized polarization of laurdan. Both MEL-A and Tween 80 modification of MHAPC-lipoplexes did not significantly change zeta potentials and surface pH levels, while MEL-A modification of OH-Chol-lipoplexes seriously decreased them. MEL-A hydrated the liposomal surface of MHAPC-lipoplexes but dehydrated that of OH-Chol-lipoplexes, while Tween 80 hydrated those of MHAPC- and OH-Chol-lipoplexes. In all, cationic liposomes composed of lipids with secondary and tertiary amine exhibited different surface properties and cellular associations of lipoplexes, and modification with surfactants further enlarged their difference. The strong hydration ability of Tween 80 may relate to the low cellular association of lipoplexes, while the dehydration of MEL-A-modified OH-Chol-lipoplexes seemed to compensate the negative zeta potential for the cellular association of lipoplexes.

  20. Role of Surface Characteristics in Urban Meteorology and Air Quality

    NASA Astrophysics Data System (ADS)

    Sailor, David Jean

    Urbanization results in a landscape with significantly modified surface characteristics. The lower values of reflectivity to solar radiation, surface moisture availability, and vegetative cover, along with the higher values of anthropogenic heat release and surface roughness combine to result in higher air temperatures in urban areas relative to their rural counterparts. Through their role in the surface energy balance and surface exchange processes, these surface characteristics are capable of modifying the local meteorology. The impacts on wind speeds, air temperatures, and mixing heights are of particular importance, as they have significant implications in terms of urban energy use and air quality. This research presents several major improvements to the meteorological modeling methodology for highly heterogeneous terrain. A land-use data base is implemented to provide accurate specification of surface characteristic variability in simulations of the Los Angeles Basin. Several vegetation parameterizations are developed and implemented, and a method for including anthropogenic heat release into the model physics is presented. These modeling advancements are then used in a series of three-dimensional simulations which were developed to investigate the potential meteorological impact of several mitigation strategies. Results indicate that application of moderate tree-planting and urban-lightening programs in Los Angeles may produce summertime air temperature reductions on the order of 4^circ C with a concomitant reduction in air pollution. The analysis also reveals several mechanisms whereby the application of these mitigation strategies may potentially increase pollutant concentrations. The pollution and energy use consequences are discussed in detail.

  1. Role of surface characteristics in urban meteorology and air quality

    SciTech Connect

    Sailor, David Jean

    1993-08-01

    Urbanization results in a landscape with significantly modified surface characteristics. The lower values of reflectivity to solar radiation, surface moisture availability, and vegetative cover, along with the higher values of anthropogenic heat release and surface roughness combine to result higher air temperatures in urban areas relative to their rural counterparts. Through their role in the surface energy balance and surface exchange processes, these surface characteristics are capable of modifying the local meteorology. The impacts on wind speeds, air temperatures, and mixing heights are of particular importance, as they have significant implications in terms of urban energy use and air quality. This research presents several major improvements to the meteorological modeling methodology for highly heterogeneous terrain. A land-use data-base is implemented to provide accurate specification of surface characteristic variability in simulations of the Los Angeles Basin. Several vegetation parameterizations are developed and implemented, and a method for including anthropogenic heat release into the model physics is presented. These modeling advancements are then used in a series of three-dimensional simulations which were developed to investigate the potential meteorological impact of several mitigation strategies. Results indicate that application of moderate tree-planting and urban-lightening programs in Los Angeles may produce summertime air temperature reductions on the order of 4°C with a concomitant reduction in air pollution. The analysis also reveals several mechanisms whereby the application of these mitigation strategies may potentially increase pollutant concentrations. The pollution and energy use consequences are discussed in detail.

  2. Synthesis and surface structural characteristics of new polysiloxane xerogel

    NASA Astrophysics Data System (ADS)

    Zasukhin, A. S.; Neudachina, L. K.; Yatluk, Yu. G.; Adamova, L. V.; Osipova, V. A.; Gorbunova, E. M.; Moskaleva, Yu. S.; Larina, T. Yu.

    2011-03-01

    Pyridylethylaminopropylpolysiloxane xerogel (PEAPPSX) was synthesized by sol-gel technology. The composition of the substance was determined via elemental analysis and 1H NMR spectroscopy. The surface structural characteristics of the xerogel were determined by electron microscopy and low-temperature nitrogen sorption; thermal analysis was also performed. It was established that the content of functional groups in PEAPPSX was 2.43 mmol/g, and that xerogel is a mesoporous substance with a developed surface (121.71 m2/g).

  3. Biocompatilibity-related surface characteristics of oxidized NiTi.

    PubMed

    Danilov, Anatoli; Tuukkanen, Tuomas; Tuukkanen, Juha; Jämsä, Timo

    2007-09-15

    In the present study, we examined the effect of NiTi oxidation on material surface characteristics related to biocompatibility. Correspondence between electron work function (EWF) and adhesive force predicted by electron theory of adsorption as well as the effect of surface mechanical stress on the adhesive force were studied on the nonoxidized and oxidized at 350, 450, and 600 degrees C NiTi alloy for medical application. The adhesive force generated by the material surface towards the drops of alpha-minimal essential medium (alpha-MEM) was used as a characteristic of NiTi adsorption properties. The study showed that variations in EWF and mechanical stress caused by surface treatment were accompanied by variations in adhesive force. NiTi oxidation at all temperatures used gave rise to decrease in adhesive force and surface stress values in comparison to the nonoxidized state. In contrary, the EWF value revealed increase under the same condition. Variations in surface oxide layer thickness and its phase composition were also followed. The important role of oxide crystallite size in EWF values within the range of crystallite dimensions typical for NiTi surface oxide as an instrument for the fine regulation of NiTi adsorption properties was demonstrated. The comparative oxidation of pure titanium and NiTi showed that the effect of Ni on the EWF value of NiTi surface oxide is negligible.

  4. A Cellular Automata Based Model for Simulating Surface Hydrological Processes in Catchments

    NASA Astrophysics Data System (ADS)

    Shao, Qi; Baumgartl, Thomas; Huang, Longbin; Weatherley, Dion

    2014-05-01

    The Runoff Model Based on Cellular Automata (RunCA) has been developed to simulate the surface hydrological processes at the catchment scale by integrating basic cellular automata (CA) rules with fundamental measureable hydraulic properties. In this model, a two-dimensional lattice composed of a series of rectangular cells was employed to cover the study area. Runoff production within each cell was simulated by determining its water depth based on the rainfall, interception, infiltration and the balance between inflows and outflows. Particularly different infiltration equations were incorporated to make the model applicable for both single rainfall event (short term simulation) and multiple rainfall events (long term simulation). The distribution of water flow among cells was determined by applying CA transition rules based on the improved minimization-of-difference algorithm and the calculated spatially and temporally varied flow velocities according to the Manning's equation. RunCA was tested and validated at two catchments (Pine Glen Basin and Snow Shoe Basin, USA) with data taken from literature. The predicted hydrographs agreed well with the measured results. Simulated flow maps also demonstrated the model capability in capturing both the spatial and temporal variations in the runoff process. Model sensitivity analysis results showed that the simulated hydrographs were mostly influenced by the input parameters that represent the final steady infiltration rate, as well as the model settings of time step and cell size. Compared to some conventional distributed hydrologic models that calculate the runoff routing process by solving complex continuity equations, this model integrates a novel method and is expected to be more computationally efficient as it is based on simple CA transition rules when determining the flow distribution.

  5. Characteristics of the ToxCast In Vitro Datasets from Biochemical and Cellular Assays

    EPA Science Inventory

    Measurement of perturbation of critical signaling pathways and cellular processes using in vitro assays provides a means to predict the potential for chemicals to cause injury in the intact animal. To explore the utility of such an approach, a diverse collection of 467 assays acr...

  6. Effect of Nanoparticle Surface Chemistry on Adsorption and Fluid Phase Partitioning in Aqueous/Toluene and Cellular Systems.

    PubMed

    Gambinossi, Filippo; Lapides, Dana; Anderson, Chris; Chanana, Munish; Ferri, James K

    2015-05-01

    Copolymers of di(ethylene glycol) methyl ether methacrylate (x = MeO2MA) and oligo(ethylene glycol) methyl ether methacrylate (y = OEGMA) display lower critical solution phenomena in aqueous systems that are tunable by the copolymer ratio (x:y), ionic strength, and temperature. These properties enable tuning the hydrophobicity of macromolecular systems by variation of (x:y). For nanoparticles stabilized with these macromolecules, this provides a systematic approach to understanding the impact of surface chemistry, specifically hydrophobicity, on the equilibrium and transport properties of nanomaterials in biphasic systems. We synthesized a homologous series of gold nanoparticles capped by these copolymers, Au@(MeO2MA(x)-co-OEGMA(y)). By varying the copolymer 95:5 < (x:y) < 80:20 ratio, we studied the effect of surface hydrophobicity on the nanoparticle equilibrium adsorption isotherm and phase transfer at the aqueous-toluene interface. The increase in hydrophobicity from (x:y) = 80:20 to (x:y) = 95:5 is accompanied by an increase in the fractional coverage of the aqueous-toluene interface from f = 0.3 to f > 1, or multilayer adsorption and an increase in the characteristic adsorption timescale from τ(D) = 31 to τ(D) = 450 seconds. The equilibrium partition coefficient for the aqueous/toluene systems, K(T/W) is also a strong function of (x:y), increasing from K(T/W) (80:20) = 0.7 to K(T/W) (95:5) = 9.8. We also observed an increase in cellular uptake for increasing (x:y) suggesting that surface chemistry alone plays a significant role in intercellular transport processes.

  7. Effect of Surface Treatment on the Surface Characteristics of AISI 316L Stainless Steel

    NASA Technical Reports Server (NTRS)

    Trigwell, Steve; Selvaduray, Guna

    2005-01-01

    The ability of 316L stainless steel to maintain biocompatibility, which is dependent upon the surface characteristics, is critical to its effectiveness as an implant material. The surfaces of mechanically polished (MP), electropolished (EP) and plasma treated 316L stainless steel coupons were characterized by X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES) for chemical composition, Atomic Force Microscopy for surface roughness, and contact angle measurements for critical surface tension. All surfaces had a Ni concentration that was significantly lower than the bulk concentration of -43%. The Cr content of the surface was increased significantly by electropolishing. The surface roughness was also improved significantly by electropolishing. Plasma treatment had the reverse effect - the surface Cr content was decreased. It was also found that the Cr and Fe in the surface exist in both the oxide and hydroxide states, with the ratios varying according to surface treatment.

  8. 10 CFR 960.5-2-8 - Surface characteristics.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 4 2012-01-01 2012-01-01 false Surface characteristics. 960.5-2-8 Section 960.5-2-8 Energy DEPARTMENT OF ENERGY GENERAL GUIDELINES FOR THE PRELIMINARY SCREENING OF POTENTIAL SITES FOR A NUCLEAR WASTE REPOSITORY Preclosure Guidelines Ease and Cost of Siting, Construction, Operation,...

  9. 10 CFR 960.5-2-8 - Surface characteristics.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Surface characteristics. 960.5-2-8 Section 960.5-2-8 Energy DEPARTMENT OF ENERGY GENERAL GUIDELINES FOR THE PRELIMINARY SCREENING OF POTENTIAL SITES FOR A NUCLEAR WASTE REPOSITORY Preclosure Guidelines Ease and Cost of Siting, Construction, Operation,...

  10. 10 CFR 960.5-2-8 - Surface characteristics.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 4 2011-01-01 2011-01-01 false Surface characteristics. 960.5-2-8 Section 960.5-2-8 Energy DEPARTMENT OF ENERGY GENERAL GUIDELINES FOR THE PRELIMINARY SCREENING OF POTENTIAL SITES FOR A NUCLEAR WASTE REPOSITORY Preclosure Guidelines Ease and Cost of Siting, Construction, Operation,...

  11. 10 CFR 960.5-2-8 - Surface characteristics.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 4 2013-01-01 2013-01-01 false Surface characteristics. 960.5-2-8 Section 960.5-2-8 Energy DEPARTMENT OF ENERGY GENERAL GUIDELINES FOR THE PRELIMINARY SCREENING OF POTENTIAL SITES FOR A NUCLEAR WASTE REPOSITORY Preclosure Guidelines Ease and Cost of Siting, Construction, Operation,...

  12. 10 CFR 960.5-2-8 - Surface characteristics.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 4 2014-01-01 2014-01-01 false Surface characteristics. 960.5-2-8 Section 960.5-2-8 Energy DEPARTMENT OF ENERGY GENERAL GUIDELINES FOR THE PRELIMINARY SCREENING OF POTENTIAL SITES FOR A NUCLEAR WASTE REPOSITORY Preclosure Guidelines Ease and Cost of Siting, Construction, Operation,...

  13. Noise characteristics of upper surface blown configurations: Summary

    NASA Technical Reports Server (NTRS)

    Reddy, N. N.; Gibson, J. S.

    1978-01-01

    A systematic experimental program was conducted to develop a data base for the noise and related flow characteristics of upper surface blown configurations. The effect of various geometric and flow parameters was investigated experimentally. The dominant noise was identified from the measured flow and noise characteristics to be generated downstream of the trailing edge. The possibilities of noise reduction techniques were explored. An upper surface blown (USB) noise prediction program was developed to calculate noise levels at any point and noise contours (footprints). Using this noise prediction program and a cruise performance data base, aircraft design studies were conducted to integrate low noise and good performance characteristics. A theory was developed for the noise from the highly sheared layer of a trailing edge wake. Theoretical results compare favorably with the measured noise of the USB model.

  14. Effect of surface roughness on characteristics of spherical shock waves

    NASA Technical Reports Server (NTRS)

    Huber, Paul W; Mcfarland, Donald R

    1955-01-01

    An investigation has been conducted on a small-scale test layout in which direct observation of the shock wave movement with time could be made in order to determine the effects of surface roughness on the characteristics of spherical shock waves. Data were obtained with 15-gram pentolite charges at four heights of burst, both for a smooth surface and for a surface completely covered with pyramid-shaped roughness elements. The observations resulted in determinations of shock peak overpressure and Mach stem height as a function of distance for each test. Comparison of the smooth-surface data with those obtained for the extremely rough condition showed a small net effort of roughness on the shock peak overpressures at the surface for all burst heights, the effect being to lower the overpressures. The effect of surface roughness on the Mach stem formation and growth was to delay the formation at the greatest charge height and to lower the height of the Mach stem for all heights.Comparison of the free-air shock peak overpressures with larger scale data showed good similarity of the overpressure-distance relationships. The data did not fit a geometrical similarity parameter for the path of the triple point at different heights of burst suggested by other investigators. A simple similarity parameter (relating the horizontal distance to the theoretical point of Mach formation) was found which showed only a small influence of burst height on the path of the triple point. While the data presented provide knowledge of the effect of many surface-roughness elements on the overall shock characteristics, the data do not provide insight into the details of the air-flow characteristics along the surface, nor the relative contribution of individual roughness elements to the results obtained.

  15. Enhanced cellular delivery of idarubicin by surface modification of propyl starch nanoparticles employing pteroic acid conjugated polyvinyl alcohol.

    PubMed

    Jain, Ratnesh; Dandekar, Prajakta; Loretz, Brigitta; Melero, Ana; Stauner, Thomas; Wenz, Gerhard; Koch, Marcus; Lehr, Claus-Michael

    2011-11-25

    Enhanced intracellular internalization of the anti-cancer active idarubicin (IDA) was achieved through appropriate surface modification of IDA loaded propyl starch nanoparticles. This was conducted by synthesizing pteroic acid modified polyvinyl alcohol (ptPVA) and employing this stabilizer for formulating the said nanoparticles. Pteroic acid attached at the nanoparticles improved the surface protein adsorption of the nanoparticle, a condition which the nanoparticles would largely experience in vitro and in vivo and hence improve their cellular internalization. Spherical, homogenous IDA nanoparticles (214 ± 5 nm) with surface modified by ptPVA were formulated using the solvent emulsification-diffusion technique. The encapsulation efficiency and drug loading amounted around 85%. In vitro release studies indicated a controlled release of IDA. Safety and efficacy of the nanoparticles was confirmed by suitable cellular cytotoxicity assays. Protein binding studies indicated a higher adsorption of the model protein on nanoparticles formulated with ptPVA as compared to PVA. Cellular uptake studies by confocal laser scanning microscopy revealed a higher cellular uptake of ptPVA stabilized nanoparticles thus confirming the proposed hypothesis of higher protein adsorption being responsible for higher cellular internalization.

  16. Surface Plasmon Resonance Fiber Sensor for Real-Time and Label-Free Monitoring of Cellular Behavior

    PubMed Central

    Shevchenko, Yanina; Camci-Unal, Gulden; Cuttica, Davide F.; Dokmeci, Mehmet R.; Albert, Jacques; Khademhosseini, Ali

    2014-01-01

    This paper reports on the application of an optical fiber biosensor for real-time analysis of cellular behavior. Our findings illustrate that a fiber sensor manufactured from a traditional telecommunication fiber can be integrated into conventional cell culture equipment and used for real-time and label-free monitoring of cellular responses to chemical stimuli. The sensing mechanism used for the measurement of cellular responses is based on the excitation of Surface Plasmon Resonance (SPR) on the surface of the optical fiber. In this proof of concept study, the sensor was utilized to investigate the influence of a number of different stimuli on cells - we tested the effects of trypsin, serum and sodium azide. These stimuli induced detachment of cells from the sensor surface, uptake of serum and inhibition of cellular metabolism, accordingly. The effects of different stimuli were confirmed with alamar blue assay, phase contrast and fluorescence microscopy. The results indicated that the fiber biosensor can be successfully utilized for real-time and label-free monitoring of cellular response in the first 30 minutes following the introduction of a stimulus. Furthermore, we demonstrated that the optical fiber biosensors can be easily regenerated for repeated use, proving this platform as a versatile and cost-effective sensing tool. PMID:24549115

  17. The cellular automata for modelling of spreading of lava flow on the earth surface

    NASA Astrophysics Data System (ADS)

    Jarna, Alexandra; Cirbus, Juraj

    2013-04-01

    Volcanic risk assessment is a very important scientific, political and economic issue in densely populated areas close to active volcanoes. Development of effective tools for early prediction of a potential volcanic hazard and management of crises are paramount. However, to this date volcanic hazard maps represent the most appropriate way to illustrate the geographical area that can potentially be affected by a volcanic event. Volcanic hazard maps are usually produced by mapping out old volcanic deposits, however dynamic lava flow simulation gaining popularity and can give crucial information to corroborate other methodologies. The methodology which is used here for the generation of volcanic hazard maps is based on numerical simulation of eruptive processes by the principle of Cellular Automata (CA). The python script is integrated into ArcToolbox in ArcMap (ESRI) and the user can select several input and output parameters which influence surface morphology, size and shape of the flow, flow thickness, flow velocity and length of lava flows. Once the input parameters are selected, the software computes and generates hazard maps on the fly. The results can be exported to Google Maps (.klm format) to visualize the results of the computation. For validation of the simulation code are used data from a real lava flow.

  18. The Cellular Automata for modelling of spreading of lava flow on the earth surface

    NASA Astrophysics Data System (ADS)

    Jarna, A.

    2012-12-01

    Volcanic risk assessment is a very important scientific, political and economic issue in densely populated areas close to active volcanoes. Development of effective tools for early prediction of a potential volcanic hazard and management of crises are paramount. However, to this date volcanic hazard maps represent the most appropriate way to illustrate the geographical area that can potentially be affected by a volcanic event. Volcanic hazard maps are usually produced by mapping out old volcanic deposits, however dynamic lava flow simulation gaining popularity and can give crucial information to corroborate other methodologies. The methodology which is used here for the generation of volcanic hazard maps is based on numerical simulation of eruptive processes by the principle of Cellular Automata (CA). The python script is integrated into ArcToolbox in ArcMap (ESRI) and the user can select several input and output parameters which influence surface morphology, size and shape of the flow, flow thickness, flow velocity and length of lava flows. Once the input parameters are selected, the software computes and generates hazard maps on the fly. The results can be exported to Google Maps (.klm format) to visualize the results of the computation. For validation of the simulation code are used data from a real lava flow. Comparison of the simulation results with real lava flows mapped out from satellite images will be presented.

  19. Characteristics of pulse corona discharge over water surface

    NASA Astrophysics Data System (ADS)

    Fujii, Tomio; Arao, Yasushi; Rea, Massimo

    2008-12-01

    Production of ozone and OH radical is required to advance the plasma chemical reactions in the NOx removal processes for combustion gas treatment. The corona discharge to the water surface is expected to induce the good conditions for the proceeding of the NO oxidation and the NO2 dissolution removal into water. In order to get the fundamental data of the corona discharge over the water surface, the positive and negative V-I characteristics and the ozone production were measured with the multi needle and the saw-edge type of the discharge electrodes. The pulse corona characteristics were also measured with some different waveforms of the applied pulse voltage. The experiments were carried out under the atmospheric pressure and room temperature. Both the DC and the pulse corona to the water surface showed a stable and almost the same V-I characteristics as to plate electrodes though the surface of water was waved by corona wind. The positive streamer corona showed more ozone production than the negative one both in the DC and in the pulse corona.

  20. Determining the source characteristics of explosions near the Earth's surface

    NASA Astrophysics Data System (ADS)

    Pasyanos, Michael E.; Ford, Sean R.

    2015-05-01

    We present a method to determine source characteristics of explosions near the Earth's surface. The technique accounts for the reduction in amplitudes as the explosion depth approaches the free surface and less energy is coupled into the ground. We apply the method to the Humming Roadrunner series of shallow explosions in New Mexico where the yields and depths are known. Knowledge of the material properties is needed for both source coupling/excitation and the free surface effect. Although there is the expected trade-off between depth and yield, the estimated yields are close to the known values when the depth is constrained to the free surface. We then apply the method to a regionally recorded explosion in Syria. We estimate an explosive yield less than the 60 t claimed by sources in the open press. The modifications to the method allow us to apply the technique to new classes of events.

  1. Microscopic Study of Surface Microtopographic Characteristics of Dental Implants

    PubMed Central

    Sezin, M.; Croharé, L.; Ibañez, J.C.

    2016-01-01

    Objective: To determine and compare the micro topographic characteristics of dental implants submitted to different surface treatments, using scanning electron microscopy (SEM). Materials and Methods: Implants were divided into 7 groups of 3 specimens each, according to the surface treatment used: group 1: Osseotite, BIOMET 3i; group 2: SLA surface, Institut Straumann AG; group 3: Oxalife surface, Tree-Oss implant; group 4: B&W implant surface; group 5: Q-implant surface; group 6: ML implant surface; group 7: RBM surface, Rosterdent implant. The surfaces were examined under SEM (Carl Zeiss FE-SEM-SIGMA). Image Proplus software was used to determine the number and mean diameter of pores per area unit (mm). The data obtained were analyzed with the Mann-Whitney test. A confocal laser microscope (LEXT-OLS4100 Olympus) was used to conduct the comparative study of surface roughness (Ra). Data were analyzed using Tukey's HSD test. Results: The largest average pore diameter calculated in microns was found in group 5 (3.45 µm+/-1.91) while the smallest in group 7 (1.47µm+/-1.29). Significant differences were observed among each one of the groups studied (p<0.05). The largest number of pores/mm2 was found in group 2 (229343) and the smallest number in group 4 (10937). Group 2 showed significant differences regarding the other groups (p<0.05). The greatest roughness (Ra) was observed in group 2 (0.975µm+/-0.115) and the smallest in group 4 (0.304µm+/-0.063). Group 2 was significantly different from the other groups (p<0.05). Conclusion: The micro topography observed in the different groups presented dissimilar and specific features, depending on the chemical treatment used for the surfaces.. PMID:27335615

  2. Reflection characteristics of a composite planar AMC surface

    NASA Astrophysics Data System (ADS)

    Hwang, Ruey-Bing; Tsai, Yueh-Lin

    2012-03-01

    This study investigates the reflection characteristics of a composite Artificial Magnetic Conductor (AMC) surface consisting of multiple orthogonal gradient AMC surfaces arranged in a two-dimensional periodic pattern. The gradient AMC surface in this study consists of square metal patches of variable size printed on a grounded dielectric substrate. Due to the orthogonal placement of the gradient AMC surface, the incident energy of a plane wave normally incident on the composite AMC surface will be reflected into four major lobes away from the impinging direction. To achieve a systematical design, a simple formula based on array antenna theory was developed to determine the reflection pattern of the gradient AMC surface illuminated by a normal incident plane wave. A time-domain full-wave simulation was also carried out to calculate the electromagnetic fields in the structure and the far-field patterns. The scattering patterns of the structure were measured in an electromagnetic anechoic chamber. Results confirm the design principle and procedures in this research. Since such a composite AMC surface can be easily fabricated using the standard printed circuit board technique without via-hole process, it may have potential applications in beam-steering and radar cross section reduction.

  3. Surface complement C3 fragments and cellular binding of microparticles in patients with SLE

    PubMed Central

    Winberg, Line Kjær; Nielsen, Claus Henrik; Jacobsen, Søren

    2017-01-01

    Objectives To examine microparticles (MPs) from patients with SLE and healthy controls (HCs) by determining the cellular origin of the MPs, quantifying attached fragments of complement component 3 (C3) and assessing the ability of MPs to bind to circulating phagocytes and erythrocytes. These features may be relevant for clearance of MPs in SLE pathogenesis. Methods Attached C3 fragments (C3b, iC3b, C3d), membrane integrity and cell surface markers of MPs from 18 patients with SLE and 11 HCs were measured by adding specific antibodies, 7-aminoactinomycin D (7AAD) and annexin V. MPs from all subjects were labelled with carboxyfluorescein diacetate succinimidyl ester and allowed to bind to autologous phagocytes and erythrocytes in the presence of autologous serum, and the binding to individual cell populations was assessed by flow cytometry. Results The proportion of MPs bearing C3 fragments was higher in patients with SLE than in HCs (p=0.026), but the amount of opsonising C3b/iC3b molecules was lower (p=0.004). The C3b/iC3b level correlated with the concentration of circulating C3 (rs=0.53, p=0.036). Phagocytes and erythrocytes from patients and HCs bound autologous MPs, and granulocytes from patients bound 13% more MPs than those from HCs (p=0.043). The presence of erythrocytes inhibited the MP binding to granulocytes by approximately 50%. Conclusions Our demonstration of altered composition of C3 fragments on MPs from patients with SLE, including decreased numbers of opsonising C3 fragments, and competitive binding of MPs to circulating phagocytes and erythrocytes corroborates the hypothesis of defective clearance of apoptotic material in SLE, and indicates that differences in both MP opsonisation and binding of MPs to cells are important in the pathogenesis of SLE.

  4. A Three-Dimensional Receiver Operator Characteristic Surface Diagnostic Metric

    NASA Technical Reports Server (NTRS)

    Simon, Donald L.

    2011-01-01

    Receiver Operator Characteristic (ROC) curves are commonly applied as metrics for quantifying the performance of binary fault detection systems. An ROC curve provides a visual representation of a detection system s True Positive Rate versus False Positive Rate sensitivity as the detection threshold is varied. The area under the curve provides a measure of fault detection performance independent of the applied detection threshold. While the standard ROC curve is well suited for quantifying binary fault detection performance, it is not suitable for quantifying the classification performance of multi-fault classification problems. Furthermore, it does not provide a measure of diagnostic latency. To address these shortcomings, a novel three-dimensional receiver operator characteristic (3D ROC) surface metric has been developed. This is done by generating and applying two separate curves: the standard ROC curve reflecting fault detection performance, and a second curve reflecting fault classification performance. A third dimension, diagnostic latency, is added giving rise to 3D ROC surfaces. Applying numerical integration techniques, the volumes under and between the surfaces are calculated to produce metrics of the diagnostic system s detection and classification performance. This paper will describe the 3D ROC surface metric in detail, and present an example of its application for quantifying the performance of aircraft engine gas path diagnostic methods. Metric limitations and potential enhancements are also discussed

  5. Survey of the finish characteristics of machined optical surfaces

    SciTech Connect

    Church, E.L.; Takacs, P.Z.

    1984-08-01

    This paper reports the findings of a survey of the finished characteristics of machined optical surfaces. The names, addresses, points of contact and telephone numbers of each of the nine participating suppliers are listed alphabetically. The machining parameters provided by and/or derived from information supplied by the manufacturer are summarized. These parameters include: surface material; machine feeds and speeds; tool-mark spacing (d); tool tip radius (R); and ideal RMS surface roughness computed using the expression (Comments) section includes general remarks about the sample or its measurement. For example: discoloration, scratches, graininess, excrescences, homogeneity. Several measurements were made on each sample at different positions. The present report includes data from one such measurement. For surfaces turned off-center, this position is generally at the center of the sample. For surfaces turned on-center, this position is somewhere near the edge. Data are presented in the form of two pages for each measurement, consisting of two graphs of the surface profile on one page and two graphs of the periodogram on the second page.

  6. Chemical and morphological characteristics of lithium electrode surfaces

    NASA Technical Reports Server (NTRS)

    Yen, S. P. S.; Shen, D.; Vasquez, R. P.; Grunthaner, F. J.; Somoano, R. B.

    1981-01-01

    Lithium electrode surfaces were analyzed for chemical and morphological characteristics, using electron spectroscopy chemical analysis (ESCA) and scanning electron microscopy (SEM). Samples included lithium metal and lithium electrodes which were cycled in a 1.5 M lithium arsenic hexafluoride/two-methyl tetrahydrofuran electrolyte. Results show that the surface of the as-received lithium metal was already covered by a film composed of LiO2 and an Li2O/CO2 adduct with a thickness of approximately 100-200 A. No evidence of Ni3 was found. Upon exposure of the lithium electrode to a 1.5 M LiAsF6/2-Me-THF electrochemical environment, a second film was observed to form on the surface, consisting primarily of As, Si, and F, possibly in the form of lithium arsenic oxyfluorides or lithium fluorosilicates. It is suggested that the film formation may be attributed to salt degradation.

  7. Virus-Surface-Mimicking Surface Clustering of AuNPs onto DNA-Entrapped Polymeric Nanoparticle for Enhanced Cellular Internalization and Nanocluster-Induced NIR Photothermal Therapy.

    PubMed

    Jia, Hui-Zhen; Chen, Wei-Hai; Wang, Xuli; Lei, Qi; Yin, Wei-Na; Wang, Yan; Zhuo, Ren-Xi; Feng, Jun; Zhang, Xian-Zheng

    2015-12-01

    Virus-surface-mimicking decoration of deoxyribonucleic acid (DNA)-entrapped polymeric nanoparticle with AuNPs is demonstrated to lead to enhanced cellular uptake, improved gene transfection, and particularly efficient near-infrared photothermal therapy that cannot be achieved by both of them separately. This hybrid nanosystem represents a novel paradigm of multipurpose organic-inorganic nanoplatform, especially for cancer treatments.

  8. Impact of poly(lactic-co-glycolic acid) nanoparticle surface charge on protein, cellular and haematological interactions.

    PubMed

    Pillai, Gopikrishna J; Greeshma, M M; Menon, Deepthy

    2015-12-01

    The initial interactions of nanoparticles with biomolecules have a great influence on its toxicity, efficacy, biodistribution and clearance. The present work is an attempt to understand the impact of surface charge of polymeric nanoparticles on its plasma protein and cellular interactions. Negative, near-neutral and positively charged poly(lactic-co-glycolic acid) [PLGA] nanoparticles were prepared using casein, poly(vinyl alcohol) and poly(ethylene imine) respectively, as surface stabilizers. A significant temporal variation in the hydrodynamic diameter of PLGA nanoparticles was observed in the presence of plasma proteins, which correlated with the amount of proteins adsorbed to each surface. Positively charged particles displayed the maximum size variation and protein adsorption. Cellular uptake of differentially charged nanoparticles was also concurrent with the quantity of adsorbed proteins, though there was no significant difference in their cytotoxicity. Haematological interactions (haemolysis and plasma coagulation times) of positively charged nanoparticles were considerably different from near-neutral and negative nanoparticles. Collectively, the results point to the interplay between plasma protein adsorption and cellular interactions of PLGA nanoparticles, which is governed by its surface charge, thereby necessitating a rational design of nanoparticles.

  9. Arecibo radar observations of Martian surface characteristics near the equator

    NASA Technical Reports Server (NTRS)

    Simpson, R. A.; Tyler, G. L.; Campbell, D. B.

    1978-01-01

    Mars radar observations at 12.6-cm wavelength indicate that many of what were potential Viking landing sites along the planet's equator are rougher than interpretations of Mariner 9 images suggested. Root mean square surface slopes are typically 5 degrees in the region bounded by 160 and 200 degrees W, 0 and 12 degrees S. From Tharsis Montes west to 160 degrees W, radar-scattering characteristics suggest extreme roughness on small scales, perhaps exceeding 10 degrees in rms magnitude. East of Tharsis and north of Valles Marineris the surface is smooth, with values of rms slope as low as 1 degree; the elevation of this plateau was too high for a Viking landing. Study of spectral shapes indicates the Hagfors scattering law remains the best descriptor of quasi-specular surface scattering properties in an average sense; widespread variations in the surface argue against its indiscriminate use, however. Backscattering at moderate (25-40 degrees) incidence angles was studied qualitatively and was found to be significantly above the level predicted by a strictly quasi-specular (e.g., Hagfors) process; it also is variable over the surface.

  10. Cellular, histomorphologic, and clinical characteristics of a new octyl-2-cyanoacrylate skin adhesive.

    PubMed

    Nitsch, Axel; Pabyk, Alfred; Honig, Johannes Franz; Verheggen, Raphaela; Merten, Hans-Albert

    2005-01-01

    Short-chained cyanoacrylates have been used for many years for topical skin closure. Toxic effects in cell culture of a new long-chained octyl-2-cyanoacrylate tissue adhesive are compared with those of short-chained ethyl-2- and butyl-2-cyanoacrylates. Two cellular tests were used: the agar overlay test and the MTT test. An in vitro test using copper plates coated with the three types of cyanoacrylates serves for evaluating the stability of polymerized skin adhesives. Bilateral neck skin incisions in Goettingen miniature pigs were glued on one side with Dermabond. On the other side, conventional sutures were applied. After the pigs were killed, the resulting skin samples were tested for the tensile strength of their wound stability. Samples of pig dermis were exemplarily and histomorphologically characterized. A clinical examination after submandibular lymph node dissection should examine the application in humans. Cell culture tests were used to show the toxic effects of the three cyanoacrylates. In a copper test, octyl-2-cyanoacrylate was more stabile than ethyl- and butyl-cyanoacrylates. Breaking strength was 30% lower 28 days after operation with the new product than with sutures. In electron microscopy, octyl-2-cyanoacrylate showed no disadvantages with regard to tissue regeneration and no histotoxicity. For plastic surgery, this new topical skin adhesive is a real alternative with attractive results, as compared with conventional suture.

  11. Dynamic corona characteristics of water droplets on charged conductor surface

    NASA Astrophysics Data System (ADS)

    Xu, Pengfei; Zhang, Bo; Wang, Zezhong; Chen, Shuiming; He, Jinliang

    2017-03-01

    The formation of the Taylor cone of a water droplet on the surface of the conductor in a line-ground electrode system is captured using a high-speed camera, while the corona current is synchronously measured using a current measurement system. Repeated Taylor cone deformation is observed, yielding regular groupings of corona current pulses. The underlying mechanism of this deformation is studied and the correlation between corona discharge characteristics and cone deformation is investigated. Depending on the applied voltage and rate of water supply, the Taylor cone may be stable or unstable and has a significant influence on the characteristics of the corona currents. If the rate of water supply is large enough, the Taylor cone tends to be unstable and generates corona-current pulses of numerous induced current pulses with low amplitudes. In consequence, this difference suggests that large rainfall results in simultaneously lower radio interference and higher corona loss.

  12. Secretory proteins characteristic of environmental changes in cellular signal transduction: Expression in oral fluid

    NASA Astrophysics Data System (ADS)

    Mednieks, M. I.; Burke, J. C.; Sivakumar, T. P.; Hand, A. R.; Grindeland, R. E.

    2000-01-01

    Past studies have shown that both hypo- and hyper-gravity have significant consequences on a variety of tissues and organ systems. It is not known if the effects of environmental stimuli such as altered gravity are beneficial or detrimental, and if the effects can be prevented or reversed. Animal experiments from the Space Lab and Cosmos missions indicate that events that are mediated by cyclic AMP, such as cellular responses to catecholamine and peptide hormone action, are significantly altered in a number of tissues as a consequence of space flight. A secretory cyclic AMP-receptor protein (cARP), is present in saliva, and can serve as an indicator of individual responses to physiologic and environmental stress. Animal experiments have shown that the hypergravity component of space flight is a significant stress factor. In humans, cARP levels in each individual are constant under normal conditions, but elevated after acute stress. Additionally, the levels of cARP in secreted saliva can be compared to those in gingival crevicular fluid (GCF), which reflects the protein composition of serum. The ratio of cARP in saliva to that in GCF can be used as a measure of basal compared to hyper-or hypo-gravity values. An ultimate goal is to test hyper and zero G responses in human saliva to determine if cARP is a suitable index of acute and chronic stress. A miniaturized test kit for saliva collection has been designed. Samples can be collected and stored till analyses are carried out that will distinguish the effects of increased gravity from those of one and zero G. Such tests can serve as an individualized monitoring system for physiologic responses either in space or on earth. .

  13. Positron states and annihilation characteristics of surface-trapped positrons at the oxidized Cu(110) surface

    NASA Astrophysics Data System (ADS)

    Fazleev, N. G.; Olenga, Antoine; Weiss, A. H.

    2013-03-01

    The process by which oxide layers are formed on metal surfaces is still not well understood. In this work we present the results of theoretical studies of positron states and annihilation characteristics of surface-trapped positrons at the oxidized Cu(110) surface. An ab-initio investigation of stability and associated electronic properties of different adsorption phases of oxygen on Cu(110) has been performed on the basis of density functional theory and using DMOl3 code. The changes in the positron work function and the surface dipole moment when oxygen atoms occupy on-surface and sub-surface sites have been attributed to charge redistribution within the first two layers, buckling effects within each layer and interlayer expansion. The computed positron binding energy, positron surface state wave function, and annihilation probabilities of surface trapped positrons with relevant core electrons demonstrate their sensitivity to oxygen coverage, elemental content, atomic structure of the topmost layers of surfaces, and charge transfer effects. Theoretical results are compared with experimental data obtained from studies of oxidized transition metal surfaces using positron annihilation induced Auger electron spectroscopy. This work was supported in part by the National Science Foundation Grant DMR-0907679.

  14. Method and apparatus for testing surface characteristics of a material

    NASA Technical Reports Server (NTRS)

    Johnson, David L. (Inventor); Kersker, Karl D. (Inventor); Richardson, David E. (Inventor); Stratton, Troy C. (Inventor)

    2006-01-01

    A method, apparatus and system for testing characteristics of a material sample is provided. The system includes an apparatus configured to house the material test sample while defining a sealed volume against a surface of the material test sample. A source of pressurized fluid is in communication with, and configured to pressurize, the sealed volume. A load applying apparatus is configured to apply a defined load to the material sample while the sealed volume is monitored for leakage of the pressurized fluid. Thus, the inducement of surface defects such as microcracking and crazing may be detected and their effects analyzed for a given material. The material test samples may include laminar structures formed of, for example, carbon cloth phenolic, glass cloth phenolic, silica cloth phenolic materials or carbon-carbon materials. In one embodiment the system may be configured to analyze the material test sample while an across-ply loading is applied thereto.

  15. Modeling of polarimetric BRDF characteristics of painted surfaces

    NASA Astrophysics Data System (ADS)

    Zhang, Ying; Wang, Zeying; Zhao, Huijie

    2014-11-01

    In this paper a pBRDF (polarimetric Bidirectional Reflectance Distribution Function) model of painted surfaces coupled with atmospheric polarization characteristics is built and the method of simulating polarimetric radiation reaching the imaging system is advanced. Firstly, the composition of the radiation reaching the sensor is analyzed. Then, the pBRDF model of painted surfaces is developed according to the microfacet theory presented by G. Priest and the downwelled skylight polarization is modeled based on the vector radiative transfer model RT3. Furthermore, the modeled polarization state of reflected light from the surfaces was achieved through integrating the directional polarimetric information of the whole hemisphere, adding the modeled polarimetric factors of incident diffused skylight. Finally, the polarimetric radiance reaching the sensor is summed up with the assumption that the target-sensor path is assumed to be negligible since it is relatively short in the current imaging geometry. The modeled results are related to the solar-sensor geometry, atmospheric conditions and the features of the painted surfaces. This result can be used to simulate the imaging under different weather conditions and further work for the validation experiments of the model need to be done.

  16. Adhesive and morphological characteristics of surface chemically modified polytetrafluoroethylene films

    NASA Astrophysics Data System (ADS)

    Hopp, B.; Kresz, N.; Kokavecz, J.; Smausz, T.; Schieferdecker, H.; Döring, A.; Marti, O.; Bor, Z.

    2004-01-01

    In the present paper, we report an experimental determination of adhesive and topographic characteristics of chemically modified surface of polytetrafluoroethylene (PTFE) films. The surface chemistry was modified by ArF excimer laser irradiation in presence of triethylene-tetramine photoreagent. The applied laser fluence was varied in the range of 0.4-9 mJ/cm 2, and the number of laser pulses incident on the same area was 1500. To detect the changes in the adhesive features of the treated Teflon samples, we measured receding contact angle for distilled water and adhesion strength, respectively. It was found that the receding contact angle decreased from 96° to 30-37° and the adhesion strength of two-component epoxy glue to the treated sample surface increased from 0.03 to 9 MPa in the applied laser fluence range. Additionally, it was demonstrated that the adhesion of human cells to the modified Teflon samples is far better than to the untreated ones. The contact mode and pulsed force mode atomic force microscopic investigations of the treated samples demonstrated that the measured effective contact area of the irradiated films does not differ significantly from that of the original films, but the derived adhesion force is stronger on the modified samples than on the untreated ones. Hence, the increased adhesion of the treated Teflon films is caused by the higher surface energy.

  17. Biosynthetic hydrogels--studies on chemical and physical characteristics on long-term cellular response for tissue engineering.

    PubMed

    Thankam, Finosh Gnanaprakasam; Muthu, Jayabalan

    2014-07-01

    Biosynthetic hydrogels can meet the drawbacks caused by natural and synthetic ones for biomedical applications. In the current article we present a novel biosynthetic alginate-poly(propylene fumarate) copolymer based chemically crosslinked hydrogel scaffolds for cardiac tissue engineering applications. Partially crosslinked PA hydrogel and fully cross linked PA-A hydrogel scaffolds were prepared. The influence of chemical and physical (morphology and architecture of hydrogel) characteristics on the long term cellular response was studied. Both these hydrogels were cytocompatible and showed no genotoxicity upon contact with fibroblast cells. Both PA and PA-A were able to resist deleterious effects of reactive oxygen species and sustain the viability of L929 cells. The hydrogel incubated oxidative stress induced cells were capable of maintaining the intra cellular reduced glutathione (GSH) expression to the normal level confirmed their protective effect. Relatively the PA hydrogel was found to be unstable in the cell culture medium. The PA-A hydrogel was able to withstand appreciable cyclic stretching. The cyclic stretching introduced complex macro and microarchitectural features with interconnected pores and more structured bound water which would provide long-term viability of around 250% after the 24th day of culture. All these qualities make PA-A hydrogel form a potent candidate for cardiac tissue engineering.

  18. Effects of 3-hydroxyflavone on the cellular and molecular characteristics of bovine embryos produced by somatic-cell nuclear transfer.

    PubMed

    Su, Jianmin; Wang, Yongsheng; Li, Wenzhe; Gao, Mingqing; Ma, Yefei; Hua, Song; Quan, Fusheng; Zhang, Yong

    2014-03-01

    This study aimed to investigate the effects of 3-hydroxyflavone, a natural antioxidant pigment enriched in vegetables, on the developmental cellular and molecular characteristics of bovine somatic-cell nuclear transfer (SCNT) embryos. There were no significant differences in the cleavage rate at 48 hr of culture or in the inner cell mass (ICM)-to-trophectoderm (TE) ratio between 3-hydroxyflavone addition and untreated (control) groups (P > 0.05). 3-hydroxyflavone (20 µM) did, however, increase the cleavage rate at 24 hr of culture and the blastocyst-formation rate on Days 6 and 7 (P < 0.05); decrease the levels of intracellular reactive oxygen species in two-, four-, and eight-cell stage embryos (P < 0.05); increase H3K9ac levels in two- and four-cell stages (P < 0.05); increase the total cell number; and decrease the apoptosis index in Day-7 blastocysts. Furthermore, the addition of 3-hydroxyflavone resulted in lower expression of the stress-related gene HSP70.1 and pro-apoptotic gene BAX, as well as higher expression of the anti-apoptotic gene BCL-xL and pluripotency-related genes OCT4 and SOX2 in Day-7 blastocysts produced by SCNT (P < 0.05). The addition of 3-hydroxyflavone during in vitro culture thus exerted beneficial effects on preimplantation development of bovine SCNT embryos both at the cellular and molecular levels.

  19. Soil and water characteristics of a young surface mine wetland

    NASA Astrophysics Data System (ADS)

    Andrew Cole, C.; Lefebvre, Eugene A.

    1991-05-01

    Coal companies are reluctant to include wetland development in reclamation plans partly due to a lack of information on the resulting characteristics of such sites. It is easier for coal companies to recreate terrestrial habitats than to attempt experimental methods and possibly face significant regulatory disapproval. Therefore, we studied a young (10 years) wetland on a reclaimed surface coal mine in southern Illinois so as to ascertain soil and water characteristics such that the site might serve as a model for wetland development on surface mines. Water pH was not measured because of equipment problems, but evidence (plant life, fish, herpetofauna) suggests suitable pH levels. Other water parameters (conductivity, salinity, alkalinity, chloride, copper, total hardness, iron, manganese, nitrate, nitrite, phosphate, and sulfate) were measured, and only copper was seen in potentially high concentrations (but with no obvious toxic effects). Soil variables measured included pH, nitrate, nitrite, ammonia, potassium, calcium, magnesium, manganese, aluminum, iron, sulfate, chloride, and percent organic matter. Soils were slightly alkaline and most parameters fell within levels reported for other studies on both natural and manmade wetlands. Aluminum was high, but this might be indicative more of large amounts complexed with soils and therefore unavailable, than amounts actually accessible to plants. Organic matter was moderate, somewhat surprising given the age of the system.

  20. Static allometry of unicellular green algae: scaling of cellular surface area and volume in the genus Micrasterias (Desmidiales).

    PubMed

    Neustupa, J

    2016-02-01

    The surface area-to-volume ratio of cells is one of the key factors affecting fundamental biological processes and, thus, fitness of unicellular organisms. One of the general models for allometric increase in surface-to-volume scaling involves fractal-like elaboration of cellular surfaces. However, specific data illustrating this pattern in natural populations of the unicellular organisms have not previously been available. This study shows that unicellular green algae of the genus Micrasterias (Desmidiales) have positive allometric surface-to-volume scaling caused by changes in morphology of individual species, especially in the degree of cell lobulation. This allometric pattern was also detected within most of the cultured and natural populations analysed. Values of the allometric S:V scaling within individual populations were closely correlated to the phylogenetic structure of the clade. In addition, they were related to species-specific cellular morphology. Individual populations differed in their allometric patterns, and their position in the allometric space was strongly correlated with the degree of allometric S:V scaling. This result illustrates that allometric shape patterns are an important correlate of the capacity of individual populations to compensate for increases in their cell volumes by increasing the surface area. However, variation in allometric patterns was not associated with phylogenetic structure. This indicates that the position of the populations in the allometric space was not evolutionarily conserved and might be influenced by environmental factors.

  1. Bacterial growth rates are influenced by cellular characteristics of individual species when immersed in electromagnetic fields.

    PubMed

    Tessaro, Lucas W E; Murugan, Nirosha J; Persinger, Michael A

    2015-03-01

    Previous studies have shown that exposure to extremely low-frequency electromagnetic fields (ELF-EMFs) have negative effects on the rate of growth of bacteria. In the present study, two Gram-positive and two Gram-negative species were exposed to six magnetic field conditions in broth cultures. Three variations of the 'Thomas' pulsed frequency-modulated pattern; a strong-static "puck" magnet upwards of 5000G in intensity; a pair of these magnets rotating opposite one another at ∼30rpm; and finally a strong dynamic magnetic field generator termed the 'Resonator' with an average intensity of 250μT were used. Growth rate was discerned by optical density (OD) measurements every hour at 600nm. ELF-EMF conditions significantly affected the rates of growth of the bacterial cultures, while the two static magnetic field conditions were not statistically significant. Most interestingly, the 'Resonator' dynamic magnetic field increased the rates of growth of three species (Staphylococcus epidermidis, Staphylococcus aureus, and Escherichia coli), while slowing the growth of one (Serratia marcescens). We suggest that these effects are due to individual biophysical characteristics of the bacterial species.

  2. Osteochondral Biopsy Analysis Demonstrates That BST-CarGel Treatment Improves Structural and Cellular Characteristics of Cartilage Repair Tissue Compared With Microfracture

    PubMed Central

    Méthot, Stéphane; Changoor, Adele; Tran-Khanh, Nicolas; Hoemann, Caroline D.; Stanish, William D.; Restrepo, Alberto; Shive, Matthew S.; Buschmann, Michael D.

    2016-01-01

    Objective The efficacy and safety of BST-CarGel, a chitosan-based medical device for cartilage repair, was compared with microfracture alone at 1 year during a multicenter randomized controlled trial (RCT) in the knee. The quality of repair tissue of osteochondral biopsies collected from a subset of patients was compared using blinded histological assessments. Methods The international RCT evaluated repair tissue quantity and quality by 3-dimensional quantitative magnetic resonance imaging as co-primary endpoints at 12 months. At an average of 13 months posttreatment, 21/41 BST-CarGel and 17/39 microfracture patients underwent elective second look arthroscopies as a tertiary endpoint, during which ICRS (International Cartilage Repair Society) macroscopic scoring was carried out, and osteochondral biopsies were collected. Stained histological sections were evaluated by blinded readers using ICRS I and II histological scoring systems. Collagen organization was evaluated using a polarized light microscopy score. Results BST-CarGel treatment resulted in significantly better ICRS macroscopic scores (P = 0.0002) compared with microfracture alone, indicating better filling, integration, and tissue appearance. Histologically, BST-CarGel resulted in a significant improvement of structural parameters—Surface Architecture (P = 0.007) and Surface/Superficial Assessment (P = 0.042)—as well as cellular parameters—Cell Viability (P = 0.006) and Cell Distribution (P = 0.032). No histological parameters were significantly better for the microfracture group. BST-CarGel treatment also resulted in a more organized repair tissue with collagen stratification more similar to native hyaline cartilage, as measured by polarized light microscopy scoring (P = 0.0003). Conclusion Multiple and independent analyses in this biopsy substudy demonstrated that BST-CarGel treatment results in improved structural and cellular characteristics of repair tissue at 1 year posttreatment compared with

  3. Silent Corticogonadotroph Adenomas: Clinical and Cellular Characteristics and Long-Term Outcomes

    PubMed Central

    Cooper, Odelia; Ben-Shlomo, Anat; Bonert, Vivien; Bannykh, Serguei; Mirocha, James

    2010-01-01

    Silent corticotrophins adenomas (SCAs) are clinically silent and non-secreting but immunostain positively for ACTH. We hypothesize that SCAs comprise both corticotroph and gonadotroph characteristics. Cohort analysis from 1994–2008 with follow-up time ranging from 1–15 years in a tertiary referral center. We compared preoperative and postoperative clinical results and tumor cytogenesis in 25 SCAs and 84 nonfunctioning adenomas in 109 consecutive patients diagnosed pre-operatively with nonfunctioning pituitary adenomas. Clinical outcomes were radiologic and hormonal measures. Pathologic outcomes were expression of relevant pituitary hormones, tissue-specific transcription factors, and electron microscopy features. Preoperative SCA presentation was similar to that observed for nonfunctioning adenomas. However, SCAs recurred postoperatively at a median of 3 years vs. 8 years for nonfunctioning adenomas (p<0.0001). Fifty-four percent of patients with SCAs had new onset postoperative hypopituitarism vs. 17% of nonfunctioning adenomas (p<0.025). SCAs (n=18) were immunopositive for ACTH, cytoplasmic and nuclear SF-1, NeuroD1, DAX-1, and alpha-gonadotropin subunit, but Tpit negative, and co-expression of tumor ACTH with either SF-1 or LH was detected. In contrast, functional corticotroph adenomas (n=11) were immunopositive for ACTH, nuclear SF-1, NeuroD1, and Tpit, but negative for DAX-1, a gonadotroph cell transcription factor. Gonadotroph adenomas (n=23) were immunonegative for ACTH and Tpit but positive for nuclear SF-1, NeuroD1, and DAX-1. SCA electron microscopy demonstrated ultrastructural features consistent with corticotroph and gonadotroph cells. As SCAs exhibit features consistent with both corticotroph and gonadotroph cytologic origin, we propose a pathologic and clinically distinct classification of SCAs as silent corticogonadotroph adenomas. PMID:20717480

  4. Surface and subsurface cracks characteristics of single crystal SiC wafer in surface machining

    NASA Astrophysics Data System (ADS)

    Qiusheng, Y.; Senkai, C.; Jisheng, P.

    2015-03-01

    Different machining processes were used in the single crystal SiC wafer machining. SEM was used to observe the surface morphology and a cross-sectional cleavages microscopy method was used for subsurface cracks detection. Surface and subsurface cracks characteristics of single crystal SiC wafer in abrasive machining were analysed. The results show that the surface and subsurface cracks system of single crystal SiC wafer in abrasive machining including radial crack, lateral crack and the median crack. In lapping process, material removal is dominated by brittle removal. Lots of chipping pits were found on the lapping surface. With the particle size becomes smaller, the surface roughness and subsurface crack depth decreases. When the particle size was changed to 1.5µm, the surface roughness Ra was reduced to 24.0nm and the maximum subsurface crack was 1.2µm. The efficiency of grinding is higher than lapping. Plastic removal can be achieved by changing the process parameters. Material removal was mostly in brittle fracture when grinding with 325# diamond wheel. Plow scratches and chipping pits were found on the ground surface. The surface roughness Ra was 17.7nm and maximum subsurface crack depth was 5.8 µm. When grinding with 8000# diamond wheel, the material removal was in plastic flow. Plastic scratches were found on the surface. A smooth surface of roughness Ra 2.5nm without any subsurface cracks was obtained. Atomic scale removal was possible in cluster magnetorheological finishing with diamond abrasive size of 0.5 µm. A super smooth surface eventually obtained with a roughness of Ra 0.4nm without any subsurface crack.

  5. Surface and subsurface cracks characteristics of single crystal SiC wafer in surface machining

    SciTech Connect

    Qiusheng, Y. Senkai, C. Jisheng, P.

    2015-03-30

    Different machining processes were used in the single crystal SiC wafer machining. SEM was used to observe the surface morphology and a cross-sectional cleavages microscopy method was used for subsurface cracks detection. Surface and subsurface cracks characteristics of single crystal SiC wafer in abrasive machining were analysed. The results show that the surface and subsurface cracks system of single crystal SiC wafer in abrasive machining including radial crack, lateral crack and the median crack. In lapping process, material removal is dominated by brittle removal. Lots of chipping pits were found on the lapping surface. With the particle size becomes smaller, the surface roughness and subsurface crack depth decreases. When the particle size was changed to 1.5µm, the surface roughness Ra was reduced to 24.0nm and the maximum subsurface crack was 1.2µm. The efficiency of grinding is higher than lapping. Plastic removal can be achieved by changing the process parameters. Material removal was mostly in brittle fracture when grinding with 325# diamond wheel. Plow scratches and chipping pits were found on the ground surface. The surface roughness Ra was 17.7nm and maximum subsurface crack depth was 5.8 µm. When grinding with 8000# diamond wheel, the material removal was in plastic flow. Plastic scratches were found on the surface. A smooth surface of roughness Ra 2.5nm without any subsurface cracks was obtained. Atomic scale removal was possible in cluster magnetorheological finishing with diamond abrasive size of 0.5 µm. A super smooth surface eventually obtained with a roughness of Ra 0.4nm without any subsurface crack.

  6. In vitro fibroblast and pre-osteoblastic cellular responses on laser surface modified Ti-6Al-4V.

    PubMed

    Chikarakara, Evans; Fitzpatrick, Patricia; Moore, Eric; Levingstone, Tanya; Grehan, Laura; Higginbotham, Clement; Vázquez, Mercedes; Bagga, Komal; Naher, Sumsun; Brabazon, Dermot

    2014-12-29

    The success of any implant, dental or orthopaedic, is driven by the interaction of implant material with the surrounding tissue. In this context, the nature of the implant surface plays a direct role in determining the long term stability as physico-chemical properties of the surface affect cellular attachment, expression of proteins, and finally osseointegration. Thus to enhance the degree of integration of the implant into the host tissue, various surface modification techniques are employed. In this work, laser surface melting of titanium alloy Ti-6Al-4V was carried out using a CO2 laser with an argon gas atmosphere. Investigations were carried out to study the influence of laser surface modification on the biocompatibility of Ti-6Al-4V alloy implant material. Surface roughness, microhardness, and phase development were recorded. Initial knowledge of these effects on biocompatibility was gained from examination of the response of fibroblast cell lines, which was followed by examination of the response of osteoblast cell lines which is relevant to the applications of this material in bone repair. Biocompatibility with these cell lines was analysed via Resazurin cell viability assay, DNA cell attachment assay, and alamarBlue metabolic activity assay. Laser treated surfaces were found to preferentially promote cell attachment, higher levels of proliferation, and enhanced bioactivity when compared to untreated control samples. These results demonstrate the tremendous potential of this laser surface melting treatment to significantly improve the biocompatibility of titanium implants in vivo.

  7. Light, shadows and surface characteristics: the multispectral Portable Light Dome

    NASA Astrophysics Data System (ADS)

    Watteeuw, Lieve; Hameeuw, Hendrik; Vandermeulen, Bruno; Van der Perre, Athena; Boschloos, Vanessa; Delvaux, Luc; Proesmans, Marc; Van Bos, Marina; Van Gool, Luc

    2016-11-01

    A multispectral, multidirectional, portable and dome-shaped acquisition system is developed within the framework of the research projects RICH (KU Leuven) and EES (RMAH, Brussels) in collaboration with the ESAT-VISICS research group (KU Leuven). The multispectral Portable Light Dome (MS PLD) consists of a hemispherical structure, an overhead camera and LEDs emitting in five parts of the electromagnetic spectrum regularly covering the dome's inside surface. With the associated software solution, virtual relighting and enhancements can be applied in a real-time, interactive manner. The system extracts genuine 3D and shading information based on a photometric stereo algorithm. This innovative approach allows for instantaneous alternations between the computations in the infrared, red, green, blue and ultraviolet spectra. The MS PLD system has been tested for research ranging from medieval manuscript illuminations to ancient Egyptian artefacts. Preliminary results have shown that it documents and measures the 3D surface structure of objects, re-visualises underdrawings, faded pigments and inscriptions, and examines the MS results in combination with the actual relief characteristics of the physical object. Newly developed features are reflection maps and histograms, analytic visualisations of the reflection properties of all separate LEDs or selected areas. In its capacity as imaging technology, the system acts as a tool for the analysis of surface materials (e.g. identification of blue pigments, gold and metallic surfaces). Besides offering support in answering questions of attribution and monitoring changes and decay of materials, the PLD also contributes to the identification of materials, all essential factors when making decisions in the conservation protocol.

  8. Platelets Cellular and Functional Characteristics in Patients with Atrial Fibrillation: A Comprehensive Meta-Analysis and Systematic Review

    PubMed Central

    Weymann, Alexander; Ali-Hasan-Al-Saegh, Sadeq; Sabashnikov, Anton; Popov, Aron-Frederik; Mirhosseini, Seyed Jalil; Nombela-Franco, Luis; Testa, Luca; Lotfaliani, Mohammadreza; Zeriouh, Mohamed; Liu, Tong; Dehghan, Hamidreza; Yavuz, Senol; de Oliveira Sá, Michel Pompeu Barros; Baker, William L.; Jang, Jae-Sik; Gong, Mengqi; Benedetto, Umberto; Dohmen, Pascal M.; D’Ascenzo, Fabrizio; Deshmukh, Abhishek J.; Biondi-Zoccai, Giuseppe; Calkins, Hugh; Stone, Gregg W.

    2017-01-01

    Background This systematic review with meta-analysis aimed to determine the strength of evidence for evaluating the association of platelet cellular and functional characteristics including platelet count (PC), MPV, platelet distribution width (PDW), platelet factor 4, beta thromboglobulin (BTG), and p-selectin with the occurrence of atrial fibrillation (AF) and consequent stroke. Material/Methods We conducted a meta-analysis of observational studies evaluating platelet characteristics in patients with paroxysmal, persistent and permanent atrial fibrillations. A comprehensive subgroup analysis was performed to explore potential sources of heterogeneity. Results Literature search of all major databases retrieved 1,676 studies. After screening, a total of 73 studies were identified. Pooled analysis showed significant differences in PC (weighted mean difference (WMD)=−26.93 and p<0.001), MPV (WMD=0.61 and p<0.001), PDW (WMD=−0.22 and p=0.002), BTG (WMD=24.69 and p<0.001), PF4 (WMD=4.59 and p<0.001), and p-selectin (WMD=4.90 and p<0.001). Conclusions Platelets play a critical and precipitating role in the occurrence of AF. Whereas distribution width of platelets as well as factors of platelet activity was significantly greater in AF patients compared to SR patients, platelet count was significantly lower in AF patients. PMID:28302997

  9. Characteristics of Planar Monopole Antenna on High Impedance Electromagnetic Surface

    NASA Technical Reports Server (NTRS)

    Scardelletti, Maximilian C.; Jastram, Nathan; Ponchak, George E.; Franklin, Rhonda R.

    2011-01-01

    This paper presents for the first time measured characteristics of a planar monopole antenna placed directly on a high impedance electromagnetic surface or artificial magnetic conductor (AMC). The return loss and radiation patterns are compared between the antenna in free space, and when placed directly on a perfect electrical conductor (PEC), and on the AMC. The antenna measured in free space has a wide pass band from 3 to 10 GHz. The return loss for the antenna on the PEC is nearly all reflected back and the return loss for the antenna on the AMC has a 10 dB bandwidth from 7.5 to 9.5 GHz. The gain of the antenna in free space, on PEC and on AMC is 1, -12 and 10 dBi, respectively. This indicates that the AMC is working properly, sending all the radiation outward with little loss.

  10. Characteristics of surface sterilization using electron cyclotron resonance plasma

    NASA Astrophysics Data System (ADS)

    Yonesu, Akira; Hara, Kazufumi; Nishikawa, Tatsuya; Hayashi, Nobuya

    2016-07-01

    The characteristics of surface sterilization using electron cyclotron resonance (ECR) plasma were investigated. High-energy electrons and oxygen radicals were observed in the ECR zone using electric probe and optical emission spectroscopic methods. A biological indicator (BI), Geobacillus stearothermophilus, containing 1 × 106 spores was sterilized in 120 s by exposure to oxygen discharges while maintaining a temperature of approximately 55 °C at the BI installation position. Oxygen radicals and high-energy electrons were found to be the sterilizing species in the ECR region. It was demonstrated that the ECR plasma could be produced in narrow tubes with an inner diameter of 5 mm. Moreover, sterilization tests confirmed that the spores present inside the narrow tube were successfully inactivated by ECR plasma irradiation.

  11. Changes in the cellular membrane surface coat of lymphocytes and thymocytes after incubation in vitro with cystein as revealed with electronmicroscopy.

    PubMed

    Borowicz, J; Olszewska, K; Roszkowski-Sliz, W; Ryzewski, J

    1977-01-01

    Changes in the cellular membrane surface coat of lymphocytes and thymocytes after incubation with cystein in vitro were revealed with electronmicroscope, while performing the reaction with Ruthenium Red and Concanavaline A. Lymphocytes and thymocytes not incubated with cystein to which reaction with Ruthenium red and Cocanavaline A was applied have shown a well developed and preserved surface coat of the cellular membrane. Contrary to this finding when lymphocytes and thymocytes were incubated with cystein and thereafter treated with Ruthenium Red and Concanavaline A no reaction product on the surface of the cellular membrane was observed. The experimental results could indicate on the influence of cystein on the glycoside bonds.

  12. Well-defined biomimetic surfaces to characterize glycosaminoglycan-mediated interactions on the molecular, supramolecular and cellular levels.

    PubMed

    Migliorini, Elisa; Thakar, Dhruv; Sadir, Rabia; Pleiner, Tino; Baleux, Françoise; Lortat-Jacob, Hugues; Coche-Guerente, Liliane; Richter, Ralf P

    2014-10-01

    Glycosaminoglycans (GAGs) are ubiquitously present at the cell surface and in extracellular matrix, and crucial for matrix assembly, cell-cell and cell-matrix interactions. The supramolecular presentation of GAG chains, along with other matrix components, is likely to be functionally important but remains challenging to control and to characterize, both in vivo and in vitro. We present a method to create well-defined biomimetic surfaces that display GAGs, either alone or together with other cell ligands, in a background that suppresses non-specific binding. Through the design of the immobilization platform - a streptavidin monolayer serves as a molecular breadboard for the attachment of various biotinylated ligands - and a set of surface-sensitive in situ analysis techniques (including quartz crystal microbalance and spectroscopic ellipsometry), the biomimetic surfaces are tailor made with tight control on biomolecular orientation, surface density and lateral mobility. Analysing the interactions between a selected GAG (heparan sulphate, HS) and the HS-binding chemokine CXCL12α (also called SDF-1α), we demonstrate that these surfaces are versatile for biomolecular and cellular interaction studies. T-lymphocytes are found to adhere specifically to surfaces presenting CXCL12α, both when reversibly bound through HS and when irreversibly immobilized on the inert surface, even in the absence of any bona fide cell adhesion ligand. Moreover, surfaces which present both HS-bound CXCL12α and the intercellular adhesion molecule 1 (ICAM-1) synergistically promote cell adhesion. Our surface biofunctionalization strategy should be broadly applicable for functional studies that require a well-defined supramolecular presentation of GAGs along with other matrix or cell-surface components.

  13. Investigation Into the Accuracy of 3D Surface Roughness Characteristics

    NASA Astrophysics Data System (ADS)

    Kumermanis, M.; Rudzitis, J.; Mozga, N.; Ancans, A.; Grislis, A.

    2014-04-01

    The existing standards for surface roughness cover only two dimensions, while in reality this is three-dimensional (3D). In particular, the 3D surface roughness parameters are important for solving the contact surface mechanics problems as related to the accuracy of 3D surface roughness characteristics. One of the most important factors for determination of 3D characteristics is the number of data points (NDP) on the x- and y-axes (i.e. in cut-off length). The NDP has a profound effect on the accuracy of measurement results, measuring time and volume of the output data (especially along the y-axis, where the NDP is identical to the number of parallel profiles). At a too small NDP the results will be incorrect and with too broad scatter, while a too large NDP - though not enlarging the range of basic information - considerably increases the measuring time. Therefore, the aim of the work was to find the optimal NDP for such surface processing methods as grinding, spark erosion and shot methods of surface treatment. Eksistējošie virsmas raupjuma standarti apskata virsmas raupjumu tikai divās dimensijās. Tomēr reālais virsmas raupjums pēc savas dabas ir trīsdimensiju (3D) objekts. Līdz ar to virsmas raupjums ir jāraksturo ar 3D parametriem. Un no šo parametru noteikšanas precizitātes ir atkarīgi tālākie virsmas aprēķini, piemēram, virsmu kontaktēšanās process. Viens no svarīgākajiem faktoriem, raksturojot virsmas raupjumu 3D, pielietojot kontakta tipa mēriekārtas, ir datu punktu skaits pa abām mērīšanas asīm x un y. Ar datu punktu skaitu mēs saprotam to skaitu mērīšanas bāzes garumā. Datu punktu skaits būtiski ietekmē sagaidāmo mērījumu rezultātu precizitāti, mērīšanai nepieciešamo laiku un izejas datu faila izmērus (sevišķi y-ass virzienā, kur katrs datu punkts ir paralēls profils). Datu punktu skaitam ir jābūt optimālam. Pārāk mazs punktu skaits noved pie neprecīziem rezultātiem un lielas to izkliedes, savuk

  14. Tuning the Surface of Nanoparticles: Impact of Poly(2-ethyl-2-oxazoline) on Protein Adsorption in Serum and Cellular Uptake.

    PubMed

    Koshkina, Olga; Westmeier, Dana; Lang, Thomas; Bantz, Christoph; Hahlbrock, Angelina; Würth, Christian; Resch-Genger, Ute; Braun, Ulrike; Thiermann, Raphael; Weise, Christoph; Eravci, Murat; Mohr, Benjamin; Schlaad, Helmut; Stauber, Roland H; Docter, Dominic; Bertin, Annabelle; Maskos, Michael

    2016-09-01

    Due to the adsorption of biomolecules, the control of the biodistribution of nanoparticles is still one of the major challenges of nanomedicine. Poly(2-ethyl-2-oxazoline) (PEtOx) for surface modification of nanoparticles is applied and both protein adsorption and cellular uptake of PEtOxylated nanoparticles versus nanoparticles coated with poly(ethylene glycol) (PEG) and non-coated positively and negatively charged nanoparticles are compared. Therefore, fluorescent poly(organosiloxane) nanoparticles of 15 nm radius are synthesized, which are used as a scaffold for surface modification in a grafting onto approach. With multi-angle dynamic light scattering, asymmetrical flow field-flow fractionation, gel electrophoresis, and liquid chromatography-mass spectrometry, it is demonstrated that protein adsorption on PEtOxylated nanoparticles is extremely low, similar as on PEGylated nanoparticles. Moreover, quantitative microscopy reveals that PEtOxylation significantly reduces the non-specific cellular uptake, particularly by macrophage-like cells. Collectively, studies demonstrate that PEtOx is a very effective alternative to PEG for stealth modification of the surface of nanoparticles.

  15. Relevant aspects in the surface properties in titanium dental implants for the cellular viability.

    PubMed

    Velasco-Ortega, E; Alfonso-Rodríguez, C A; Monsalve-Guil, L; España-López, A; Jiménez-Guerra, A; Garzón, I; Alaminos, M; Gil, F J

    2016-07-01

    Roughness and topographical features are the most relevant of the surface properties for a dental implant for its osseointegration. For that reason, we studied the four surfaces more used in titanium dental implants: machined, sandblasted, acid etching and sandblasted plus acid etching. The roughness and wettability (contact angle and surface free energy) was studied by means 3D-interferometric microscope and sessile drop method. Normal human gingival fibroblasts (HGF) were obtained from small oral mucosa biopsies and were used for cell cultures. To analyze cell integrity, we first quantified the total amount of DNA and LDH released from dead cells to the culture medium. Then, LIVE/DEAD assay was used as a combined method assessing cell integrity and metabolism. All experiments were carried out on each cell type cultured on each Ti material for 24h, 48h and 72h. To evaluate the in vivo cell adhesion capability of each Ti surface, the four types of discs were grafted subcutaneously in 5 Wistar rats. Sandblasted surfaces were significantly rougher than acid etching and machined. Wettability and surface free energy decrease when the roughness increases in sand blasted samples. This fact favors the protein adsorption. The DNA released by cells cultured on the four Ti surfaces did not differ from that of positive control cells (p>0.05). The number of cells per area was significantly lower (p<0.05) in the sand-blasted surface than in the machined and surface for both cell types (7±2 cells for HGF and 10±5 cells for SAOS-2). The surface of the machined-type discs grafted in vivo had a very small area occupied by cells and/or connective tissue (3.5%), whereas 36.6% of the sandblasted plus acid etching surface, 75.9% of sandblasted discs and 59.6% of acid etching discs was covered with cells and connective tissue. Cells cultured on rougher surfaces tended to exhibit attributes of more differentiated osteoblasts than cells cultured on smoother surfaces. These surface

  16. Effect of surface charge on the cellular uptake of fluorescent magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Kralj, Slavko; Rojnik, Matija; Romih, Rok; Jagodič, Marko; Kos, Janko; Makovec, Darko

    2012-10-01

    We report on the nanoparticle uptake into MCF10A neoT and PC-3 cells using flow cytometry, confocal microscopy, SQUID magnetometry, and transmission electron microscopy. The aim was to evaluate the influence of the nanoparticles' surface charge on the uptake efficiency. The surface of the superparamagnetic, silica-coated, maghemite nanoparticles was modified using amino functionalization for the positive surface charge (CNPs), and carboxyl functionalization for the negative surface charge (ANPs). The CNPs and ANPs exhibited no significant cytotoxicity in concentrations up to 500 μg/cm3 in 24 h. The CNPs, bound to a plasma membrane, were intensely phagocytosed, while the ANPs entered cells through fluid-phase endocytosis in a lower internalization degree. The ANPs and CNPs were shown to be co-localized with a specific lysosomal marker, thus confirming their presence in lysosomes. We showed that tailoring the surface charge of the nanoparticles has a great impact on their internalization.

  17. Development of a cell culture surface conversion technique using alginate thin film for evaluating effect upon cellular differentiation.

    PubMed

    Nakashima, Y; Tsusu, K; Minami, K; Nakanishi, Y

    2014-06-01

    Here, we sought to develop a cell culture surface conversion technique that would not damage living cells. An alginate thin film, formed on a glass plate by spin coating of sodium alginate solution and dipping into calcium chloride solution, was used to inhibit adhesion of cells. The film could be removed by ethylenediaminetetraacetate (EDTA) at any time during cell culture, permitting observation of cellular responses to conversion of the culture surface in real time. Additionally, we demonstrated the validity of the alginate thin film coating method and the performance of the film. The thickness of the alginate thin film was controlled by varying the rotation speed during spin coating. Moreover, the alginate thin film completely inhibited the adhesion of cultured cells to the culture surface, irrespective of the thickness of the film. When the alginate thin film was removed from the culture surface by EDTA, the cultured cells adhered to the culture surface, and their morphology changed. Finally, we achieved effective differentiation of C2C12 myoblasts into myotube cells by cell culture on the convertible culture surface, demonstrating the utility of our novel technique.

  18. Development of a cell culture surface conversion technique using alginate thin film for evaluating effect upon cellular differentiation

    SciTech Connect

    Nakashima, Y.; Tsusu, K.; Minami, K.; Nakanishi, Y.

    2014-06-15

    Here, we sought to develop a cell culture surface conversion technique that would not damage living cells. An alginate thin film, formed on a glass plate by spin coating of sodium alginate solution and dipping into calcium chloride solution, was used to inhibit adhesion of cells. The film could be removed by ethylenediaminetetraacetate (EDTA) at any time during cell culture, permitting observation of cellular responses to conversion of the culture surface in real time. Additionally, we demonstrated the validity of the alginate thin film coating method and the performance of the film. The thickness of the alginate thin film was controlled by varying the rotation speed during spin coating. Moreover, the alginate thin film completely inhibited the adhesion of cultured cells to the culture surface, irrespective of the thickness of the film. When the alginate thin film was removed from the culture surface by EDTA, the cultured cells adhered to the culture surface, and their morphology changed. Finally, we achieved effective differentiation of C2C12 myoblasts into myotube cells by cell culture on the convertible culture surface, demonstrating the utility of our novel technique.

  19. Surface Energy Budget Characteristics and Surface Energy Imbalance over Chinese Loess Plateau

    NASA Astrophysics Data System (ADS)

    Li, Hongyu; Zhang, Qiang; Guo, Weidong; Fu, Congbin; Shi, Jinsen

    2013-04-01

    Field observation of land-surface processes is a fundamental approach to quantitatively measure mass and energy exchanges between the land surface and the atmosphere. Chinese Loess Plateau, a unique landscape in the world, is known as a transitional zone both in terms of climate and ecosystem. Land-surface process measurement helps to better understand the aridity trend and the ecosystem change over Chinese Loess Plateau. Based on data collected at the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) from June 2008 to June 2010, we analyzed the characteristics of land surface radiation and energy budget in summer, as well as the surface energy imbalance issues over Chinese Loess Plateau. Main results are concluded as follows: (1)By studying impacts of different weather conditions on micrometeorological characteristics, the clouds and the precipitation contribute disturbances by about 25 to each component of energy balance. Weakening impact of clouds and precipitation on surface energy budget is much stronger than that in desert and Gobi region. Furthermore, it shows that the mean climatic characteristics in summer relatively close to those of cloudy days. (2)To investigate the land surface energy imbalance over the Loess Plateau, we estimated the heat storage associated with change of air temperature and humidity as well as the energy stored in plants due to the photosynthesis, which determines the vertical water transport and soil temperature at the shadow soil layers. The peaks of averaged diurnal variation of energy storages by air and plant photosynthesis reach 1.5 and 2.0 W m-2 respectively. In addition, the peak of diurnal variation of mean heat flux transferred by vertical water movement can reach nearly 8.0 W m-2. The closure of energy balance is improved from 88.1% to 89.6% by adding the three additional energy terms mentioned above to the energy balance equation. We found that the special climate background and vegetation

  20. Influence of water/O₂ plasma treatment on cellular responses of PCL and PET surfaces.

    PubMed

    Türkoğlu Şaşmazel, Hilal; Aday, Sezin; Manolache, Sorin; Gümüşderelioğlu, Menemşe

    2011-01-01

    In this study, low pressure water/O₂ plasma treatment was performed in order to obtain COOH functionalities on the surface of poly-ε-caprolactone (PCL) membranes as well as non-woven polyester fabric (NWPF) discs. The plasma treatments were performed in a cylindrical, capacitively coupled RF-plasma-reactor and then following steps were performed: in situ (oxalyl chloride vapors) gas/solid reaction to convert -OH functionalities into -COCl groups; and hydrolysis under open laboratory conditions using air moisture for final-COOH functionalities. COOH and OH functionalities on modified surfaces were detected quantitatively by using fluorescent labeling technique and an UVX 300G sensor. Electron spectroscopy for chemical analysis (ESCA) was used to evaluate the relative surface atomic compositions and the carbon and oxygen linkages located in non-equivalent atomic positions of untreated and modified surfaces. Atomic force microscope (AFM) analysis showed that nanoscale features of the PCL surfaces are dramatically changed during the surface treatments. Scanning electron microscopy (SEM) results indicated the changes in the relatively smooth appearance of the untreated NWPF discs after the plasma treatment. Periodontal ligament (PDL) fibroblasts were used in cell culture studies. Cell culture results showed that plasma treated PCL membranes and NWPF discs were favorable for the PDL cell spreading, growth and viability due to the presence of functional groups and/or nanotopographies on their surfaces.

  1. Investigation of cellular and protein interactions with model self-assembled monolayer surfaces

    NASA Astrophysics Data System (ADS)

    Tegoulia, Vassiliki Apostolou

    Self-assembled monolayers (SAMs) of alkanethiolates on gold have been used to investigate the effect of substrate surface properties on bacterial and blood cell adhesion in the presence and absence of blood proteins. Protein adsorption and binding strength on SAMs as well as complement activation by these model surfaces were also studied. It is hoped that information gained, regarding factors that influence biological processes, will lead to strategies for designing materials and surfaces that specifically inhibit cell adhesion and protein adsorption. Single component SAMs of the general formula HS(CH2) 10X, where X = CH3, CH2OH. COOH and CH2(OCH 2CH2)3OH, and two component mixed SAMs created from binary solutions of HS(CH2), OCH3 and HS(CH 2)10CH2OH, were used. Adhesion was investigated under well-defined flow conditions. Adhesion was found to be higher for the hydrophobic methyl and minimal for the tri(ethyleneoxide) terminated SAM. Preincubation of the SAMs with fibrinogen led to an increase in cell adhesion for bacteria and a decrease for leukocyte adhesion. The effect of surface chemistry on protein adsorption was studied for three blood proteins, fibrinogen, fibronectin and albumin. Adsorption was found to be higher on the hydrophobic CH3 surface and lower but comparable for the other surfaces while proteins adsorbed strongly on all surfaces. SAMs were also used to evaluate complement activation by foreign surfaces. The hydroxyl rich SAMs were found to activate complement more significantly than the anionic carboxyl and the hydrophobic methyl terminated SAMs. A surface modification was introduced to incorporate a zwitterionic phosphorylcholine (PC) group on a hydroxyl monolayer in an effort to create a biomimetic surface that could minimize cell adhesion and protein adsorption. The good antifouling properties of the phosphorylcholine modified surface led to the synthesis of a novel phosphorylcholine functionalized thiol. Single component and two component

  2. A propagating ATPase gradient drives transport of surface-confined cellular cargo

    NASA Astrophysics Data System (ADS)

    Vecchiarelli, Anthony; Neuman, Keir; Mizuuchi, Kiyoshi

    2014-03-01

    The process of DNA segregation is of central importance for all organisms. Although eukaryotic mitosis is relatively well established, the most common mechanism employed for bacterial DNA segregation has been unclear. ParA ATPases form dynamic patterns on the bacterial nucleoid, to spatially organize plasmids, chromosomes and other large cellular cargo, but the force generating mechanism has been a source of controversy and debate. A dominant view proposes that ParA-mediated transport and cargo positioning occurs via a filament-based mechanism that resembles eukaryotic mitosis. Here we present direct evidence against such models. Our cell-free reconstitution supports a non-filament-based mode of transport that may be as widely found in nature as actin filaments and microtubules.

  3. Quantification of Inert Gas Monolayer Evolution on an Atomically Rough Calcium (111) Surface Using Cellular Automata

    DTIC Science & Technology

    2007-11-02

    role in determining surface coverage at these high fluxes2. -4.8- -5.0- curves statistics (averaged over 10 runs) -5.2 - 0020 - -5.4 0.0401 eV -0,025 2c...imperfection in figure 12 for an 8% Ar flux at 90 K. The total perimeter does not approach zero for a perfect initial surface due to thermal fluctuation

  4. Cellular automaton simulation of the diffusive motion of bacteria and their adhesion to nanostructures on a solid surface.

    PubMed

    Yamamoto, Takehiro; Emura, Chie; Oya, Masashi

    2016-12-01

    The growth of a biofilm begins with the adhesion of bacteria to a solid surface. Consequently, biofilm growth can be managed by the control of bacterial adhesion. Recent experimental studies have suggested that bacterial adhesion can be controlled by modifying a solid surface using nanostructures. Computational prediction and analysis of bacterial adhesion behavior are expected to be useful for the design of effective arrangements of nanostructures for controlling bacterial adhesion. The present study developed a cellular automaton (CA) model for bacterial adhesion simulation that could describe both the diffusive motion of bacteria and dependence of their adhesion patterns on the distance between nanostructures observed in experimental studies. The diffusive motion was analyzed by the moment scaling spectrum theory, and the present model was confirmed to describe subdiffusion behavior due to obstacles. Adhesion patterns observed in experimental studies can be successfully simulated by introducing CA rules to describe a mechanism by which bacteria tend to move to increase the area of contact with nanostructures.

  5. Antioxidant activity of rosmarinic acid and its principal metabolites in chemical and cellular systems: Importance of physico-chemical characteristics.

    PubMed

    Adomako-Bonsu, Amma G; Chan, Sue Lf; Pratten, Margaret; Fry, Jeffrey R

    2017-04-01

    Persistent accumulation of reactive oxygen species causes cellular oxidative stress which contributes strongly towards the induction and progression of various diseases. Therapeutic focus has therefore shifted towards the use of antioxidants, with recent interest in those of plant origin. In the current study, rosmarinic acid (RA) and its key metabolites were evaluated in non-cellular and cellular antioxidant assays, using quercetin (Q) as a positive control. The non-cellular assay was performed as scavenging of DPPH radical, whilst the cellular assay was performed as protection from an oxidant stress. Radical-scavenging activity of RA and two of its primary metabolites, CA and DHPLA, were comparable to that of Q, whilst FA was of lower potency and m-CoA was inactive. In the cellular assay, RA and CA were markedly less potent than Q, with DHPLA, FA and m-CoA being inactive, this being true in short-term (5-h) or long-term (20-h) exposure conditions. However, antioxidant potency of Q and methyl rosmarinate, a non-ionisable ester of RA, was similar in the non-cellular and short-term cellular assays. It is proposed that marked ionisation of organic acids such as RA and its metabolites at physiological pH greatly limits their intracellular accumulation, and so attenuates intrinsic antioxidant ability demonstrated in the non-cellular assay. This study demonstrates some of the factors that prevent well-known phytochemicals from progressing further along the drug discovery chain.

  6. A review of chemical surface modification of bioceramics: effects on protein adsorption and cellular response.

    PubMed

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

    2014-10-01

    Calcium phosphates (CaPs) are ideal biomaterials for bone repair because of the similarities between their chemical structure and the mineral phase of hard biological tissues (e.g., bones and teeth). Since CaP bone grafts exhibit superior biocompatibility and strong osseointegration properties, they have been widely investigated for use as an in situ carrier for delivery of anti-resorptive and osteogenic drugs. The surface properties of CaP govern the affinity and the binding mechanisms between biological macromolecules (e.g., proteins) and the CaP surface, which indirectly determines the interactions between bone cells and implanted CaP biomaterials. These surface properties ultimately play a pivotal role in determining the success of CaP as bone implants and/or drug carriers. This review provides an in-depth discussion of the current methodologies used to regulate the surface chemistry of CaP and their subsequent effects in regards to protein adsorption and delivery, as well as cell/materials interactions.

  7. Cell-surface sensors for real-time probing of cellular environments

    NASA Astrophysics Data System (ADS)

    Zhao, Weian; Schafer, Sebastian; Choi, Jonghoon; Yamanaka, Yvonne J.; Lombardi, Maria L.; Bose, Suman; Carlson, Alicia L.; Phillips, Joseph A.; Teo, Weisuong; Droujinine, Ilia A.; Cui, Cheryl H.; Jain, Rakesh K.; Lammerding, Jan; Love, J. Christopher; Lin, Charles P.; Sarkar, Debanjan; Karnik, Rohit; Karp, Jeffrey M.

    2011-08-01

    The ability to explore cell signalling and cell-to-cell communication is essential for understanding cell biology and developing effective therapeutics. However, it is not yet possible to monitor the interaction of cells with their environments in real time. Here, we show that a fluorescent sensor attached to a cell membrane can detect signalling molecules in the cellular environment. The sensor is an aptamer (a short length of single-stranded DNA) that binds to platelet-derived growth factor (PDGF) and contains a pair of fluorescent dyes. When bound to PDGF, the aptamer changes conformation and the dyes come closer to each other, producing a signal. The sensor, which is covalently attached to the membranes of mesenchymal stem cells, can quantitatively detect with high spatial and temporal resolution PDGF that is added in cell culture medium or secreted by neighbouring cells. The engineered stem cells retain their ability to find their way to the bone marrow and can be monitored in vivo at the single-cell level using intravital microscopy.

  8. Cell-surface sensors for real-time probing of cellular environments

    PubMed Central

    Zhao, Weian; Schafer, Sebastian; Choi, Jonghoon; Yamanaka, Yvonne J.; Lombardi, Maria L.; Bose, Suman; Carlson, Alicia L.; Phillips, Joseph A.; Teo, Weisuong; Droujinine, Ilia A.; Cui, Cheryl H.; Jain, Rakesh K.; Lammerding, Jan; Love, J. Christopher; Lin, Charles P.; Sarkar, Debanjan; Karnik, Rohit; Karp, Jeffrey M.

    2011-01-01

    The ability to explore cell signalling and cell-to-cell communication is essential for understanding cell biology and developing effective therapeutics. However, it is not yet possible to monitor the interaction of cells with their environments in real time. Here, we show that a fluorescent sensor attached to a cell membrane can detect signalling molecules in the cellular environment. The sensor is an aptamer (a short length of single-stranded DNA) that binds to platelet-derived growth factor (PDGF) and contains a pair of fluorescent dyes. When bound to PDGF, the aptamer changes conformation and the dyes come closer to each other, producing a signal. The sensor, which is covalently attached to the membranes of mesenchymal stem cells, can quantitatively detect with high spatial and temporal resolution PDGF that is added in cell culture medium or secreted by neighbouring cells. The engineered stem cells retain their ability to find their way to the bone marrow and can be monitored in vivo at the single-cell level using intravital microscopy. PMID:21765401

  9. [INVITED] Laser treatment of Inconel 718 alloy and surface characteristics

    NASA Astrophysics Data System (ADS)

    Yilbas, B. S.; Ali, H.; Al-Aqeeli, N.; Karatas, C.

    2016-04-01

    Laser surface texturing of Inconel 718 alloy is carried out under the high pressure nitrogen assisting gas. The combination of evaporation and melting at the irradiated surface is achieved by controlling the laser scanning speed and the laser output power. Morphological and metallurgical changes in the treated surface are analyzed using the analytical tools including optical, electron scanning, and atomic force microscopes, energy dispersive spectroscopy, and X-ray diffraction. Microhardnes and friction coefficient of the laser treated surface are measured. Residual stress formed in the surface region is determined from the X-ray diffraction data. Surface hydrophobicity of the laser treated layer is assessed incorporating the sessile drop method. It is found that laser treated surface is free from large size asperities including cracks and the voids. Surface microhardness increases significantly after the laser treatment process, which is attributed to the dense layer formation at the surface under the high cooling rates, dissolution of Laves phase in the surface region, and formation of nitride species at the surface. Residual stress formed is compressive in the laser treated surface and friction coefficient reduces at the surface after the laser treatment process. The combination of evaporation and melting at the irradiated surface results in surface texture composes of micro/nano-poles and pillars, which enhance the surface hydrophobicity.

  10. Mycoplasma hyopneumoniae and Mycoplasma flocculare differential domains from orthologous surface proteins induce distinct cellular immune responses in mice.

    PubMed

    Leal, Fernanda Munhoz Dos Anjos; Virginio, Veridiana Gomes; Martello, Carolina Lumertz; Paes, Jéssica Andrade; Borges, Thiago J; Jaeger, Natália; Bonorino, Cristina; Ferreira, Henrique Bunselmeyer

    2016-07-15

    Mycoplasma hyopneumoniae and Mycoplasma flocculare are two genetically close species found in the swine respiratory tract. Despite their similarities, while M. hyopneumoniae is the causative agent of porcine enzootic pneumonia, M. flocculare is a commensal bacterium. Genomic and transcriptional comparative analyses so far failed to explain the difference in pathogenicity between these two species. We then hypothesized that such difference might be, at least in part, explained by amino acid sequence and immunological or functional differences between ortholog surface proteins. In line with that, it was verified that approximately 85% of the ortholog surface proteins from M. hyopneumoniae 7448 and M. flocculare present one or more differential domains. To experimentally assess possible immunological implications of this kind of difference, the extracellular differential domains from one pair of orthologous surface proteins (MHP7448_0612, from M. hyopneumoniae, and MF_00357, from M. flocculare) were expressed in E. coli and used to immunize mice. The recombinant polypeptides (rMHP61267-169 and rMF35767-196, respectively) induced distinct cellular immune responses. While, rMHP61267-169 induced both Th1 and Th2 responses, rMF35767-196 induced just an early pro-inflammatory response. These results indicate that immunological properties determined by differential domains in orthologous surface protein might play a role in pathogenicity, contributing to elicit specific and differential immune responses against each species.

  11. Effect of Gold Nanorod Surface Chemistry on Cellular Interactions In Vitro

    DTIC Science & Technology

    2010-09-01

    properties of GNRs on cells. Previous studies on the cytotoxicity of various nanoparticles indicated that surface chemistry has a strong influence on cell...supplemented with 10% fetal bovine serum (FBS, ATCC) and 1% penicillin/streptomycin (pen/strep, Sigma). For nanoparticle exposure, media was supplemented...reagent ( phenazine ethosulfate; PES). Metabolically active cells reduce the MTS compound into a colored formazan product that is soluble in tissue

  12. Cytotoxicity of quantum dots used for in vitro cellular labeling: role of QD surface ligand, delivery modality, cell type, and direct comparison to organic fluorophores.

    PubMed

    Bradburne, Christopher E; Delehanty, James B; Boeneman Gemmill, Kelly; Mei, Bing C; Mattoussi, Hedi; Susumu, Kimihiro; Blanco-Canosa, Juan B; Dawson, Philip E; Medintz, Igor L

    2013-09-18

    Interest in taking advantage of the unique spectral properties of semiconductor quantum dots (QDs) has driven their widespread use in biological applications such as in vitro cellular labeling/imaging and sensing. Despite their demonstrated utility, concerns over the potential toxic effects of QD core materials on cellular proliferation and homeostasis have persisted, leaving in question the suitability of QDs as alternatives for more traditional fluorescent materials (e.g., organic dyes, fluorescent proteins) for in vitro cellular applications. Surprisingly, direct comparative studies examining the cytotoxic potential of QDs versus these more traditional cellular labeling fluorophores remain limited. Here, using CdSe/ZnS (core/shell) QDs as a prototypical assay material, we present a comprehensive study in which we characterize the influence of QD dose (concentration and incubation time), QD surface capping ligand, and delivery modality (peptide or cationic amphiphile transfection reagent) on cellular viability in three human cell lines representing various morphological lineages (epithelial, endothelial, monocytic). We further compare the effects of QD cellular labeling on cellular proliferation relative to those associated with a panel of traditionally employed organic cell labeling fluorophores that span a broad spectral range. Our results demonstrate the important role played by QD dose, capping ligand structure, and delivery agent in modulating cellular toxicity. Further, the results show that at the concentrations and time regimes required for robust QD-based cellular labeling, the impact of our in-house synthesized QD materials on cellular proliferation is comparable to that of six commercial cell labeling fluorophores. Cumulatively, our results demonstrate that the proper tuning of QD dose, surface ligand, and delivery modality can provide robust in vitro cell labeling reagents that exhibit minimal impact on cellular viability.

  13. Effect of surface characteristics on retention and removal of Escherichia coli O157:H7 on surfaces of spinach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The topography and the spatial heterogeneity of produce surfaces may impact the attachment of microbial cells onto produce surfaces and affect disinfection efficacy. In this study, the effects of produce surface characteristics on the removal of bacteria were studied. Fresh spinach leaves were sp...

  14. The effect of neutral-surface iron oxide nanoparticles on cellular uptake and signaling pathways

    PubMed Central

    Kim, Eunjoo; Kim, Joon Mee; Kim, Lucia; Choi, Suk Jin; Park, In Suh; Han, Jee Young; Chu, Young Chae; Choi, Eun Sook; Na, Kun; Hong, Soon-Sun

    2016-01-01

    In recent years, iron oxide nanoparticles (IONPs) have been applied widely to biomedical fields. However, the relationship between the physicochemical properties of IONPs and their biological behavior is not fully understood yet. We prepared 3-methacryloxypropyltrimethoxysilane (MPS)-coated IONPs, which have a neutral hydrophobic surface, and compared their biological behavior to that of Resovist (ferucarbotran), a commercialized IONP formulation modified with carboxymethyl dextran. The rate of MPS-IONP uptake by human aortic endothelial cells (HAoECs) was higher than ferucarbotran uptake, indicating that the neutral hydrophobic nature of MPS-IONPs allowed them to be absorbed more readily through the plasma membrane. However, the signaling pathways activated by MPS-IONPs and ferucarbotran were comparable, suggesting that surface charge is not a key factor for inducing changes in HAoECs. In vivo fate analysis showed that MPS-IONPs accumulated for longer periods in tissues than hydrophilic ferucarbotran. These findings could enlarge our understanding of NP behavior for advanced applications in the biomedical field. PMID:27695320

  15. Surface characteristics of two-component thallium-bismuth melts

    NASA Astrophysics Data System (ADS)

    Ashkhotov, O. G.; Ashkhotova, I. B.; Aleroev, M. A.; Bliev, A. P.; Magkoev, T. T.

    2017-02-01

    The surface tension of pure Tl and Bi, and two-component alloys of them over the range of volume concentrations and temperatures starting from the liquidus temperature up to 623 K are measured by the lying-drop method with strong control over the surface condition by means of Auger electron spectroscopy. The results from in situ measurements of the surface tensions of Tl and Bi with surfactant impurities, and for atomically pure surfaces and Tl-Bi solutions, are given. It is shown that surfaces are enriched by bismuth, the concentration of which grows along with temperature.

  16. Synergistic effect of topography, surface chemistry and conductivity of the electrospun nanofibrous scaffold on cellular response of PC12 cells.

    PubMed

    Tian, Lingling; Prabhakaran, Molamma P; Hu, Jue; Chen, Menglin; Besenbacher, Flemming; Ramakrishna, Seeram

    2016-09-01

    Electrospun nanofibrous nerve implants is a promising therapy for peripheral nerve injury, and its performance can be tailored by chemical cues, topographical features as well as electrical properties. In this paper, a surface modified, electrically conductive, aligned nanofibrous scaffold composed of poly (lactic acid) (PLA) and polypyrrole (Ppy), referred to as o-PLAPpy_A, was fabricated for nerve regeneration. The morphology, surface chemistry and hydrophilicity of nanofibers were characterized by Scanning Electron Microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and water contact angle, respectively. The effects of these nanofibers on neuronal differentiation using PC12 cells were evaluated. A hydrophilic surface was created by Poly-ornithine coating, which was able to provide a better environment for cell attachment, and furthermore aligned fibers were proved to be able to guide PC12 cells grow along the fiber direction and be beneficial for neurite outgrowth. The cellular response of PC12 cells to pulsed electrical stimulation was evaluated by NF 200 and alpha tubulin expression, indicating that electrical stimulation with a voltage of 40mV could enhance the neurite outgrowth. The PC12 cells stimulated with electrical shock showed greater level of neurite outgrowth and smaller cell body size. Moreover, the PC12 cells under electrical stimulation showed better viability. In summary, the o-PLAPpy_A nanofibrous scaffold supported the attachment, proliferation and differentiation of PC12 cells in the absence of electrical stimulation, which could be potential candidate for nerve regeneration applications.

  17. Origami interleaved tube cellular materials

    NASA Astrophysics Data System (ADS)

    Cheung, Kenneth C.; Tachi, Tomohiro; Calisch, Sam; Miura, Koryo

    2014-09-01

    A novel origami cellular material based on a deployable cellular origami structure is described. The structure is bi-directionally flat-foldable in two orthogonal (x and y) directions and is relatively stiff in the third orthogonal (z) direction. While such mechanical orthotropicity is well known in cellular materials with extruded two dimensional geometry, the interleaved tube geometry presented here consists of two orthogonal axes of interleaved tubes with high interfacial surface area and relative volume that changes with fold-state. In addition, the foldability still allows for fabrication by a flat lamination process, similar to methods used for conventional expanded two dimensional cellular materials. This article presents the geometric characteristics of the structure together with corresponding kinematic and mechanical modeling, explaining the orthotropic elastic behavior of the structure with classical dimensional scaling analysis.

  18. Integrated automated nanomanipulation and real-time cellular surface imaging for mechanical properties characterization

    NASA Astrophysics Data System (ADS)

    Eslami, Sohrab; Zareian, Ramin; Jalili, Nader

    2012-10-01

    Surface microscopy of individual biological cells is essential for determining the patterns of cell migration to study the tumor formation or metastasis. This paper presents a correlated and effective theoretical and experimental technique to automatically address the biophysical and mechanical properties and acquire live images of biological cells which are of interest in studying cancer. In the theoretical part, a distributed-parameters model as the comprehensive representation of the microcantilever is presented along with a model of the contact force as a function of the indentation depth and mechanical properties of the biological sample. Analysis of the transfer function of the whole system in the frequency domain is carried out to characterize the stiffness and damping coefficients of the sample. In the experimental section, unlike the conventional atomic force microscope techniques basically using the laser for determining the deflection of microcantilever's tip, a piezoresistive microcantilever serving as a force sensor is implemented to produce the appropriate voltage and measure the deflection of the microcantilever. A micromanipulator robotic system is integrated with the MATLAB® and programmed in such a way to automatically control the microcantilever mounted on the tip of the micromanipulator to achieve the topography of biological samples including the human corneal cells. For this purpose, the human primary corneal fibroblasts are extracted and adhered on a sterilized culture dish and prepared to attain their topographical image. The proposed methodology herein allows an approach to obtain 2D quality images of cells being comparatively cost effective and extendable to obtain 3D images of individual cells. The characterized mechanical properties of the human corneal cell are furthermore established by comparing and validating the phase shift of the theoretical and experimental results of the frequency response.

  19. Integrated automated nanomanipulation and real-time cellular surface imaging for mechanical properties characterization.

    PubMed

    Eslami, Sohrab; Zareian, Ramin; Jalili, Nader

    2012-10-01

    Surface microscopy of individual biological cells is essential for determining the patterns of cell migration to study the tumor formation or metastasis. This paper presents a correlated and effective theoretical and experimental technique to automatically address the biophysical and mechanical properties and acquire live images of biological cells which are of interest in studying cancer. In the theoretical part, a distributed-parameters model as the comprehensive representation of the microcantilever is presented along with a model of the contact force as a function of the indentation depth and mechanical properties of the biological sample. Analysis of the transfer function of the whole system in the frequency domain is carried out to characterize the stiffness and damping coefficients of the sample. In the experimental section, unlike the conventional atomic force microscope techniques basically using the laser for determining the deflection of microcantilever's tip, a piezoresistive microcantilever serving as a force sensor is implemented to produce the appropriate voltage and measure the deflection of the microcantilever. A micromanipulator robotic system is integrated with the MATLAB(®) and programmed in such a way to automatically control the microcantilever mounted on the tip of the micromanipulator to achieve the topography of biological samples including the human corneal cells. For this purpose, the human primary corneal fibroblasts are extracted and adhered on a sterilized culture dish and prepared to attain their topographical image. The proposed methodology herein allows an approach to obtain 2D quality images of cells being comparatively cost effective and extendable to obtain 3D images of individual cells. The characterized mechanical properties of the human corneal cell are furthermore established by comparing and validating the phase shift of the theoretical and experimental results of the frequency response.

  20. [Influence of microcystin-LR on cell viability and surface characteristics of Pseudomonas putida].

    PubMed

    Deng, Ting-jin; Ye, Jin-shao; Peng, Hui; Liu, Zhi-chen; Liu, Ze-hua; Yin, Hua; Chen, Shuo-na

    2015-01-01

    In microcystin-LR (MC-LR) degradation system, the change in surface characteristics and cell viability of Pseudomonas putida was studied. The purpose of this study was to reveal the influence of MC-LR on P. putida and elucidate the toxicity of MC-LR on microorganisms. The result demonstrated that MC-LR enhanced the cytoplasmic membrane permeability, as well as affected the ion metabolism and protein release of P. putida. The soluble sugar and Na+, Cl-release increased with the rising concentration of MC-LR ranging from 0 mg x L(-1) to 2.0 mg x L(-1). Flow Cytometry Method(FCM) analysis revealed that MC-LR accelerated the death of P. putida, and the death rate increased with the ascending concentration of MC-LR. Compared with the control, the death rate on day 5 increased by nearly 30% when 2.5 mg x L(-1) MC-LR was added. Scanning electron microscopy (SEM) analysis showed that the cells were deformed under the toxicity of MC-LR. After 5-day exposure to 2.5 mg x L(-1) MC-LR, the majority of the cells were ruptured and the intracellular materials flew out. The cellular structure was severely damaged under this condition.

  1. Characteristics of meter-scale surface electrical discharge propagating along water surface at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Hoffer, Petr; Sugiyama, Yuki; Hosseini, S. Hamid R.; Akiyama, Hidenori; Lukes, Petr; Akiyama, Masahiro

    2016-10-01

    This paper reports physical characteristics of water surface discharges. Discharges were produced by metal needle-to-water surface geometry, with the needle electrode driven by 47 kV (FWHM) positive voltage pulses of 2 µs duration. Propagation of discharges along the water surface was confined between glass plates with 2 mm separation. This allowed generation of highly reproducible 634 mm-long plasma filaments. Experiments were performed using different atmospheres: air, N2, and O2, each at atmospheric pressure. Time- and spatially-resolved spectroscopic measurements revealed that early spectra of discharges in air and nitrogen atmospheres were dominated by N2 2nd positive system. N2 radiation disappeared after approx. 150 ns, replaced by emissions from atomic hydrogen. Spectra of discharges in O2 atmosphere were dominated by emissions from atomic oxygen. Time- and spatially-resolved emission spectra were used to determine temperatures in plasma. Atomic hydrogen emissions showed excitation temperature of discharges in air to be about 2  ×  104 K. Electron number densities determined by Stark broadening of the hydrogen H β line reached a maximum value of ~1018 cm-3 just after plasma initiation. Electron number densities and temperatures depended only slightly on distance from needle electrode, indicating formation of high conductivity leader channels. Direct observation of discharges by high speed camera showed that the average leader head propagation speed was 412 km · s-1, which is substantially higher value than that observed in experiments with shorter streamers driven by lower voltages.

  2. The toxicity of plastic nanoparticles to green algae as influenced by surface modification, medium hardness and cellular adsorption.

    PubMed

    Nolte, Tom M; Hartmann, Nanna B; Kleijn, J Mieke; Garnæs, Jørgen; van de Meent, Dik; Jan Hendriks, A; Baun, Anders

    2017-02-01

    To investigate processes possibly underlying accumulation and ecological effects of plastic nano-particles we have characterized their interaction with the cell wall of green algae. More specifically, we have investigated the influence of particle surface functionality and water hardness (Ca(2+) concentration) on particle adsorption to algae cell walls. Polystyrene nanoparticles with different functional groups (non-functionalized, -COOH and -NH2) as well as coated (starch and PEG) gold nanoparticles were applied in these studies. Depletion measurements and atomic force microscopy (AFM) showed that adsorption of neutral and positively charged plastic nanoparticles onto the cell wall of P. subcapitata was stronger than that of negatively charged plastic particles. Results indicated that binding affinity is a function of both inter-particle and particle-cell wall interactions which are in turn influenced by the medium hardness and particle concentration. Physicochemical modelling using DLVO theory was used to interpret the experimental data, using also values for interfacial surface free energies. Our study shows that material properties and medium conditions play a crucial role in the rate and state of nanoparticle bio-adsorption for green algae. The results show that the toxicity of nanoparticles can be better described and assessed by using appropriate dose metrics including material properties, complexation/agglomeration behavior and cellular attachment and adsorption. The applied methodology provides an efficient and feasible approach for evaluating potential accumulation and hazardous effects of nanoparticles to algae caused by particle interactions with the algae cell walls.

  3. Cellular distribution and molecular heterogeneity of MAC393 antigen (clusterin, beta-chain) on the surface membrane of bull spermatozoa.

    PubMed

    Howes, E A; Hurst, S; Laslop, A; Jones, R

    1998-07-01

    The distribution and size of a surface membrane antigen identified by a monoclonal antibody (MAC9393) have been examined in testicular and epididymal bovine sperm preparations. Western blots indicated a substantial decrease in molecular mass of the antigen during epididymal maturation from approximately 87 kDa in the testis to approximately 35 kDa in the cauda epididymidis. This was accompanied by a change in its cellular localization from the neck and whole head to the acrosomal region. N-terminal microsequencing identified MAC393 antigen as the beta-chain of clusterin. A polyclonal antiserum to the alpha-chain of clusterin recognized both testicular and epididymal forms and revealed that the heterodimer was present on the sperm tail as well as the acrosome. These findings are explained by the co-existence of dimeric and monomeric pools of clusterin on spermatozoa. The polyclonal antiserum recognizes both testicular and epididymal forms of the heterodimer and although the monoclonal antibody binds to the testicular heterodimer, it only recognizes the beta-chain monomer of epididymal clusterin. These findings support previous observations made on human spermatozoa that two forms of clusterin, the beta-chain monomer and the heterodimer, are present on the surface membrane and in seminal plasma.

  4. Contributions of adhesive proteins to the cellular and bacterial response to surfaces treated with bioactive polymers: case of poly(sodium styrene sulfonate) grafted titanium surfaces.

    PubMed

    Felgueiras, Helena P; Aissa, Ines Ben; Evans, Margaret D M; Migonney, Véronique

    2015-11-01

    The research developed on functionalized model or prosthetic surfaces with bioactive polymers has raised the possibility to modulate and/or control the biological in vitro and in vivo responses to synthetic biomaterials. The mechanisms underlying the bioactivity exhibited by sulfonated groups on surfaces involves both selective adsorption and conformational changes of adsorbed proteins. Indeed, surfaces functionalized by grafting poly(sodium styrene sulfonate) [poly(NaSS)] modulate the cellular and bacterial response by inducing specific interactions with fibronectin (Fn). Once implanted, a biomaterial surface is exposed to a milieu of many proteins that compete for the surface which dictates the subsequent biological response. Once understood, this can be controlled by dictating exposure of active binding sites. In this in vitro study, we report the influence of binary mixtures of proteins [albumin (BSA), Fn and collagen type I (Col I)] adsorbed on poly(NaSS) grafted Ti6Al4V on the adhesion and differentiation of MC3T3-E1 osteoblast-like cells and the adhesion and proliferation of Staphylococcus aureus (S. aureus). Outcomes showed that poly(NaSS) stimulated cell spreading, attachment strength, differentiation and mineralization, whatever the nature of protein provided at the interface compared with ungrafted Ti6Al4V (control). While in competition, Fn and Col I were capable of prevailing over BSA. Fn played an important role in the early interactions of the cells with the surface, while Col I was responsible for increased alkaline phosphatase, calcium and phosphate productions associated with differentiation. Poly(NaSS) grafted surfaces decreased the adhesion of S. aureus and the presence of Fn on these chemically altered surfaces increased bacterial resistance ≈70% compared to the ungrafted Ti6Al4V. Overall, our study showed that poly(NaSS) grafted Ti6Al4V selectively adsorbed proteins (particularly Fn) promoting the adhesion and differentiation of osteoblast

  5. Characteristics of Pool Boiling on Graphite-Copper Composite Surfaces

    NASA Technical Reports Server (NTRS)

    Zhang, Nengli; Chao, David F.; Yang, Wen-Jei

    2002-01-01

    Nucleate pool boiling performance of different liquids on graphite-copper composite (Gr-Cu) surfaces has been experimentally studied and modeled. Both highly wetting fluids, such as freon-113 and pentane, and a moderately wetting fluid (water) were tested on the Gr-Cu surfaces with different graphite-fiber volume fractions to reveal the enhancement effects of the composite surfaces on the nucleate pool boiling. Results of the experiments show that the graphite-fiber volume fraction has an optimum value. The Gr-Cu composite surface with 25 percent graphite-fiber volume (f=0.25) has a maximum enhancement effect on the nucleate boiling heat transfer comparing to the pure copper surface. For the highly wetting fluid, the nucleate boiling heat transfer is generally enhanced on the Gr- Cu composite surfaces by 3 to 6 times shown. In the low heat flux region, the enhancement is over 6 times, but in the high heat flux region, the enhancement is reduced to about 40%. For the moderately wetting fluid (water), stronger enhancement of nucleate boiling heat transfer is achieved on the composite surface. It shown the experimental results in which one observes the nucleate boiling heat transfer enhancement of 5 to 10 times in the low heat flux region and an enhancement of 3 to 5 times in the high heat flux region. Photographs of bubble departure during the initial stage of nucleate boiling indicate that the bubbles detached from the composite surface are much smaller in diameter than those detached from the pure copper surface. Typical photographs are presented.It shows that the bubbles departed from the composite surface have diameters of only O(0.1) mm, while those departed from the pure copper surface have diameters of O(1) mm. It is also found that the bubbles depart from the composite surface at a much higher frequency, thus forming vapor columns. These two phenomena combined with high thermal conductivity of the graphite fiber are considered the mechanisms for such a

  6. Effect of nitride chemical passivation of the surface of GaAs photodiodes on their characteristics

    NASA Astrophysics Data System (ADS)

    Kontrosh, E. V.; Lebedeva, N. M.; Kalinovskiy, V. S.; Soldatenkov, F. Yu; Ulin, V. P.

    2016-11-01

    Characteristics of GaAs photodiodes have been studied before and after the chemical nitridation of their surface in hydrazine sulfide solutions, which leads to substitution of surface As atoms with N atoms to give a GaN monolayer. The resulting nitride coatings hinder the oxidation of GaAs in air and provide a decrease in the density of surface states involved in recombination processes. The device characteristics improved by nitridation are preserved during a long time.

  7. Application of surface-linked liposomal antigens to the development of vaccines that induce both humoral and cellular immunity.

    PubMed

    Uchida, Tetsuya; Taneichi, Maiko

    2014-01-01

    The first characteristic identified in surface-linked liposomal antigens was the ability to induce antigen-specific, IgE-selective unresponsiveness. These results remained consistent even when different coupling procedures were employed for antigens with liposomes or for liposomes with different lipid components. The potential usefulness of surface-linked liposomal antigens for application to vaccine development was further investigated. During this investigation, a significant difference was observed in the recognition of liposomal antigens by antigen-presenting cells between liposomes with different lipid components, and this difference correlated closely with the adjuvant activity of liposomes. In addition to this "quantitative" difference between liposomes with differential lipid components, a "qualitative" difference (i.e., a differential ability to induce cross-presentation) was observed between liposomes with different lipid components. Therefore, by utilizing the ability to induce cross-presentation, surface-linked liposomal antigens might be used to develop virus vaccines that would induce cytotoxic T lymphocyte (CTL) responses. We have successfully developed a liposome vaccine that is capable of inducing CTL responses against internal antigens of influenza viruses and thus removing virus-infected cells in the host. This CTL-based liposomal vaccine might be applicable to the development of vaccines against influenza and other viruses that frequently undergo changes in their surface antigenic molecules.

  8. Characteristics of Immunochemical Interrelations between Cellular Components Included into the Composition of Allergenoactive Fractions of Enterobacteria of Various Genera,

    DTIC Science & Technology

    Cellular components which form allergenoactive fractions include antigens common to enterobacteria of different genera. In Escherichia, Shigella...The degree of immunochemical community is expressed identically for individual examples of enterobacteria . According to the number of common antigens...in the allergenic fractions, enterobacteria can be divided into four immunochemical types: Escherichia (combines the genera Escherichia, Salmonella

  9. Drag reduction characteristics of small amplitude rigid surface waves

    NASA Technical Reports Server (NTRS)

    Cary, A. M., Jr.; Weinstein, L. M.; Bushnell, D. M.

    1980-01-01

    The possibility of reducing drag by using rigid, wavy surfaces is investigated both analytically and experimentally. Although pressure drag for rigid sine-wave surfaces can be predicted empirically, viscous drag for even shallow waves was poorly predicted by state-of-the-art turbulent boundary layer calculation procedures. Calculations for the effects of geometric and fluid variables on total wave drag are presented under the philosophy that trends will be nearly correct even though levels are probably incorrect. Experiments by the present authors indicate that a total drag reduction with wavy walls is possible.

  10. Effect of Surface Roughness on Characteristics of Spherical Shock Waves

    NASA Technical Reports Server (NTRS)

    Huber, Paul W.; McFarland, Donald R.

    1959-01-01

    Measurements of peak overpressure and Mach stem height were made at four burst heights. Data were obtained with instrumentation capable of directly observing the variation of shock wave movement with time. Good similarity of free air shock peak overpressure with larger scale data was found to exist. The net effect of surface roughness on shock peak overpressures slightly. Surface roughness delayed the Mach stem formation at the greatest charge height and lowered the growth at all burst heights. A similarity parameter was found which approximately correlates the triple point path at different burst heights.

  11. Wind Characteristics of Coastal and Inland Surface Flows

    NASA Astrophysics Data System (ADS)

    Subramanian, Chelakara; Lazarus, Steven; Jin, Tetsuya

    2015-11-01

    Lidar measurements of the winds in the surface layer (up to 80 m) inland and near the beach are studied to better characterize the velocity profile and the effect of roughness. Mean and root-mean-squared profiles of horizontal and vertical wind components are analyzed. The effects of variable time (18, 60 and 600 seconds) averaging on the above profiles are discussed. The validity of common surface layer wind profile models to estimate skin friction drag is assessed in light of these measurements. Other turbulence statistics such as auto- and cross- correlations in spatial and temporal domains are also presented. The help of FIT DMES field measurement crew is acknowledged.

  12. Approximating the head characteristics and characteristic surfaces of dynamic pumps by means of an exponential function

    NASA Astrophysics Data System (ADS)

    Shekun, G. D.

    2009-08-01

    Results obtained from statistical and experimental studies of the head characteristics of commercially available centrifugal and free-vortex pumps are presented. A regression equation in the form of an exponential function written in a reduced-relative system of coordinates for approximating the head characteristics of blade pumps is obtained.

  13. Friction-factor characteristics for narrow channels with honeycomb surfaces

    NASA Technical Reports Server (NTRS)

    Ha, T. W.; Morrison, G. L.; Childs, D. W.

    1992-01-01

    The experimental determination of friction-factors for the flow of air in a narrow channel lined with various honeycomb geometries has been carried out. Test results show that, generally, the friction-factor is nearly constant or slightly decreases as the Reynolds number increases, a characteristic common to turbulent flow in pipes. However, in some test geometries this trend is remarkably different. The friction factor dramatically drops and then rises as the Reynolds number increases. This phenomenon can be characterized as a 'friction-factor jump'. Further investigations of the acoustic spectrum and friction-factor measurements for a broad range of Reynolds numbers indicate that the 'friction-factor jump' phenomenon is accompanied by an onset of a normal mode resonance excited coherent flow fluctuation structure, which occurs at Reynolds number of the order of 10,000. The purpose of this paper is to explain the friction-factor-jump phenomenon and friction-factor characteristics.

  14. Alkyne-Modulated Surface-Enhanced Raman Scattering-Palette for Optical Interference-Free and Multiplex Cellular Imaging.

    PubMed

    Chen, Yong; Ren, Jia-Qiang; Zhang, Xia-Guang; Wu, De-Yin; Shen, Ai-Guo; Hu, Ji-Ming

    2016-06-21

    The alkyne tags possess unique interference-free Raman emissions but are still hindered for further application in the field of biochemical labels due to its extremely weak spontaneous Raman scattering. With the aid of computational chemistry, herein, an alkyne-modulated surface-enhanced Raman scattering (SERS) palette is constructed based on rationally designed 4-ethynylbenzenethiol derivatives for spectroscopic signature, Au@Ag core for optical enhancement and an encapsulating polyallylamine shell for protection and conjugation. Even for the pigment rich plant cell (e.g., pollen), the alkyne-coded SERS tag can be highly discerned on two-dimension distribution impervious to strong organic interferences originating from resonance-enhanced Raman scattering or autofluorescence. In addition, the alkynyl-containing Raman reporters contribute especially narrow emission, band shift-tunable (2100-2300 cm(-1)) and tremendously enhanced Raman signals when the alkynyl group locates at para position of mercaptobenzene ring. Depending on only single Raman band, the suggested alkyne-modulated SERS-palette potentially provides a more effective solution for multiplex cellular imaging with vibrant colors, when the hyperspectral and fairly intense optical noises originating from lower wavenumber region (<1800 cm(-1)) are inevitable under complex ambient conditions.

  15. How the knowledge of genetic "makeup" and cellular data can affect the analysis of repolarization in surface electrocardiogram.

    PubMed

    Shimizu, Wataru

    2010-01-01

    This review article sought to describe patterns of repolarization on the surface electrocardiogram in inherited cardiac arrhythmias and to discuss how the knowledge of genetic makeup and cellular data can affect the analysis based on the data derived from the experimental studies using arterially perfused canine ventricular wedge preparations. Molecular genetic studies have established a link between a number of inherited cardiac arrhythmia syndromes and mutations in genes encoding cardiac ion channels or membrane components during the past 2 decades. Twelve forms of congenital long QT syndrome have been so far identified, and genotype-phenotype correlations have been investigated especially in the 3 major genotypes-LQT1, LQT2, and LQT3. Abnormal T waves are reported in the LQT1, LQT2, and LQT3, and the differences in the time course of repolarization of the epicardial, midmyocardial, and endocardial cells give rise to voltage gradients responsible for the manifestation of phenotypic appearance of abnormal T waves. Brugada syndrome is characterized by ST-segment elevation in leads V1 to V3 and an episode of ventricular fibrillation, in which 7 genotypes have been reported. An intrinsically prominent transient outward current (I(to))-mediated action potential notch and a subsequent loss of action potential dome in the epicardium, but not in the endocardium of the right ventricular outflow tract, give rise to a transmural voltage gradient, resulting in ST-segment elevation, and a subsequent phase 2 reentry-induced ventricular fibrillation. In conclusion, transmural electrical heterogeneity of repolarization across the ventricular wall profoundly affects the phenotypic manifestation of repolarization patterns on the surface electrocardiogram in inherited cardiac arrhythmias.

  16. Surface and semantic processing of cellular transport representations by high school students with low and high prior knowledge

    NASA Astrophysics Data System (ADS)

    Cook, Michelle Patrick

    The purpose of this study was to examine the influence of prior knowledge of cell transport processes on how students viewed and interpreted visual representations related to that topic. The participants were high school students (n=65) enrolled in Advanced Placement biology. Prior knowledge was assessed using a modified version of the Diffusion and Osmosis Diagnostic Test (Odom & Barrow, 1995). Eye movements were measured to reveal how students distribute their visual attention as they perceive and interpret graphics; in addition, interviews and questionnaires were employed to provide more interpretive data sources. The first manuscript of the study investigates the relationship between prior knowledge and students' ability to perceive salient features and interpret graphic representations of cellular transport. The results from eye tracking data, interviews, and questionnaire responses were triangulated and revealed differences in how high and low prior knowledge students attended to and interpreted various features of the graphic representations. Without adequate domain knowledge, low prior knowledge students focused on surface features of the graphics to build an understanding of the concepts represented. High prior knowledge students, with more abundant and better organized domain knowledge, were more likely to attend to thematically relevant content in the graphics and construct deeper understandings. The second manuscript of the study examines the influence of prior knowledge on how students transitioned among the macroscopic and molecular representations of selected graphics. Eye tracking and sequential analysis results indicated that high prior knowledge students transitioned more frequently between the molecular representations, where as low prior knowledge students transitioned more frequently between the macroscopic representations. In addition, low prior knowledge students transitioned more frequently between macroscopic and molecular representations

  17. Radar, visual and thermal characteristics of Mars - Rough planar surfaces

    NASA Technical Reports Server (NTRS)

    Schaber, G. G.

    1980-01-01

    High-resolution Viking Orbiter images contain significant information on Martian surface roughness at 25- to 100-m lateral scales, while earth-based radar observations of Mars are sensitive to roughness at lateral scales of 1 to 30 m or more. High-rms slopes predicted for the Tharsis-Memnonia-Amazonis volcanic plains from extremely weak radar returns are qualitatively confirmed by the Viking image data. Large-scale, curvilinear ridges on lava flows in the Memnonia Fossae region are interpreted as innate flow morphology caused by compressional foldover of moving lava sheets of possible rhyolite-dacite composition. The presence or absence of a recent mantle of fine-grained eolian material on the volcanic surfaces studied was determined by the visibility of fresh impact craters with diameters less than 50 m. Lava flows with surfaces modified by eolian erosion and deposition occur west-northwest of Apollinaris Patera at the border of the cratered equatorial uplands and southern Elysium Planitia. Nearby yardangs, for which radar observations indicate very high-rms slopes, are similar to terrestrial features of similar origin.

  18. Tribological characteristics of a composite total-surface hip replacement

    NASA Technical Reports Server (NTRS)

    Jones, W. R., Jr.; Roberts, J. C.; Ling, F. F.

    1982-01-01

    Continuous fiber, woven E glass composite femoral shells having the same elastic properties as bone were fabricated. The shells were then encrusted with filled epoxy wear resistant coatings and run dry against ultrahigh molecular weight polyethylene acetabular cups in 42,000 and 250,000 cycle wear tests on a total hip simulator. The tribological characteristics of these continuous fiber particulate composite femoral shells articulating with ultrahigh molecular weight polyethylene acetabular cups were comparable to those of a vitallium ball articulating with an ultrahigh molecular weight polyethylene acetabular cup.

  19. Membrane Surface-Associated Helices Promote Lipid Interactions and Cellular Uptake of Human Calcitonin-Derived Cell Penetrating Peptides

    PubMed Central

    Herbig, Michael E.; Weller, Kathrin; Krauss, Ulrike; Beck-Sickinger, Annette G.; Merkle, Hans P.; Zerbe, Oliver

    2005-01-01

    hCT(9-32) is a human calcitonin (hCT)-derived cell-penetrating peptide that has been shown to translocate the plasma membrane of mammalian cells. It has been suggested as a cellular carrier for drugs, green fluorescent protein, and plasmid DNA. Because of its temperature-dependent cellular translocation resulting in punctuated cytoplasmatic distribution, its uptake is likely to follow an endocytic pathway. To gain insight into the molecular orientation of hCT(9-32) when interacting with lipid models, and to learn more about its mode of action, various biophysical techniques from liposome partitioning to high-resolution NMR spectroscopy were utilized. Moreover, to establish the role of individual residues for the topology of its association with the lipid membrane, two mutants of hCT(9-32), i.e., W30-hCT(9-32) and A23-hCT(9-32), were also investigated. Although unstructured in aqueous solution, hCT(9-32) adopted two short helical stretches when bound to dodecylphosphocholine micelles, extending from Thr10 to Asn17 and from Gln24 to Val29. A23-hCT(9-32), in which the helix-breaking Pro23 was replaced by Ala, displayed a continuous α-helix extending from residue 12 to 26. Probing with the spin label 5-doxylstearate revealed that association with dodecylphosphocholine micelles was such that the helix engaged in parallel orientation to the micelle surface. Moreover, the Gly to Trp exchange in W30-hCT(9-32) resulted in a more stable anchoring of the C-terminal segment close to the interface, as reflected by a twofold increase in the partition coefficient in liposomes. Interestingly, tighter binding to model membranes was associated with an increase in the in vitro uptake in human cervix epithelial andenocarcinoma cell line cells. Liposome leakage studies excluded pore formation, and the punctuated fluorescence pattern of internalized peptide indicated vesicular localization and, in conclusion, strongly suggested an endocytic pathway of translocation. PMID:16183886

  20. A Novel Water-Soluble Fluorescence Probe with Wash-Free Cellular Imaging Capacity Based on AIE Characteristics.

    PubMed

    Qian, Yunxia; Liu, Hongmei; Tan, Haijian; Yang, Qingmin; Zhang, Shuchen; Han, Lingui; Yi, Xuegang; Huo, Li; Zhao, Hongchi; Wu, Yonggang; Bai, Libin; Ba, Xinwu

    2017-03-21

    A potential real-time imaging water-soluble fluorescent polymer (P3) is facilely prepared via one-pot method. For P3, tetraphenylethene unit serves as the fluorescent unit, poly(acryloyl ethylene diamine) (a kind of polyelectrolyte) with specific degree of polymerization acts as water-soluble part. (1) H-NMR, gel permeation chromatography (GPC), UV-vis spectroscopy, photoluminescence (PL), and confocal laser scanning microscopy are undertaken to characterize the structure and property of P3. The results of wash-free cellular imaging show that the signal-to-noise ratio is high as the concentration of P3 is 50 μg mL(-1) . In addition, the pH-responsive and Cd(2+) -responsive are also investigated in this paper. The results coming from pH-responsive show that P3 solution displays significant fluorescence under near neutral. And the result from the cellular imaging shows that intracellular fluorescence intensity enhances with the augment of concentration of Cd(2+) , which reveals that P3 can give a hint to resolve the dilemma of traditional fluorescent dyes used as living cellular fluorescent probe.

  1. Exploring the proteomic characteristics of the Escherichia coli B and K-12 strains in different cellular compartments.

    PubMed

    Han, Mee-Jung

    2016-07-01

    Escherichia coli, one of the well-characterized prokaryotes, has been the most widely used bacterial host in scientific studies and industrial applications. Many different strains have been developed for the widespread use of E. coli in biotechnology, and selecting an ideal host to produce a specific protein of interest is a critical step in developing a production process. The E. coli B and K-12 strains are among the most frequently used bacterial hosts for the production of recombinant proteins as well as small-molecule metabolites such as amino acids, biofuels, carboxylic acids, diamines, and others. However, both strains have distinctive differences in genotypic and phenotypic attributes, and their behaviors can still be unpredictable at times, especially while expressing a recombinant protein. Therefore, in this review, an in-depth analysis of the physiological behavior on the proteomic level was performed, wherein the particularly distinct proteomic differences between the E. coli B and K-12 strains were investigated in the four distinctive cellular compartments. Interesting differences in the proteins associated with key cellular properties including cell growth, protein production and quality, cellular tolerance, and motility were observed between the two representative strains. The resulting enhancement of knowledge regarding host physiology that is summarized herein is expected to contribute to the acceleration of strain improvements and optimization for biotechnology-related processes.

  2. Non-Destructive Analysis of Basic Surface Characteristics of Titanium Dental Implants Made by Miniature Machining

    NASA Astrophysics Data System (ADS)

    Babík, Ondrej; Czán, Andrej; Holubják, Jozef; Kameník, Roman; Pilc, Jozef

    2016-12-01

    One of the most best-known characteristic and important requirement of dental implant is made of biomaterials ability to create correct interaction between implant and human body. The most implemented material in manufacturing of dental implants is titanium of different grades of pureness. Since most of the implant surface is in direct contact with bone tissue, shape and integrity of said surface has great influence on the successful osseointegration. Among other characteristics of titanium that predetermine ideal biomaterial, it shows a high mechanical strength making precise machining miniature Increasingly difficult. The article is focused on evaluation of the resulting quality, integrity and characteristics of dental implants surface after machining.

  3. Evaluation of In-Plane Microdeformation Distribution Characteristics of Polishing Pad Surface

    NASA Astrophysics Data System (ADS)

    Uneda, Michio; Omote, Tatsunori; Shibuya, Kazutaka; Nakamura, Yoshio; Ichikawa, Daizo; Ishikawa, Ken-ichi

    2013-05-01

    In the chemical mechanical polishing (CMP) of a Si wafer, the physical properties of the polishing pad affect the processing characteristics. There have been several studies on the evaluation of pad surface asperity. In this study, we investigate the fundamental characteristics of polishing pads by the digital image correlation (DIC) method from two viewpoints. It was found that the pad surface deforms owing to shrinkage. Moreover, there is a strong relationship between the in-plane microdeformation characteristics and the amount of material removed from the pad in the conditioning process. Since the DIC method can measure changes in pad surface conditions, it can be used to evaluate future CMP monitoring systems.

  4. Radar, visual and thermal characteristics of Mars: Rough planar surfaces

    USGS Publications Warehouse

    Schaber, G.G.

    1980-01-01

    High-resolution Viking Orbiter images (10 to 15 m/pixel) contain significant information on Martian surface roughness at 25- to 100-m lateral scales, whereas Earth-based radar observations of Mars are sensitive to roughness at lateral scales of 1 to 30 m, or more. High-rms slopes predicted for the Tharsis-Memnonia-Amazonis volcanic plains from extremely weak radar returns (low peak radar cross section) are qualitatively confirmed by the Viking image data. Large-scale, curvilinear (but parallel) ridges on lava flows in the Memnonia Fossae region are interpreted as innate flow morphology caused by compressional foldover of moving lava sheets of possible rhyolite-dacite composition. The presence or absence of a recent mantle of fine-grained eolian material on the volcanic surfaces studied was determined by the visibility of fresh impact craters with diameters less than 50 m. Lava flows south and west of Arsia Mons, and within the large region of low thermal inertia centered on Tharsis Montes (H. H. Kieffer et al., 1977, J. Geophys. Res.82, 4249-4291), were found to possess such a recent mantle. At predawn residual temperatures ??? -10K (south boundary of this low-temperature region), lava flows are shown to have relatively old eolian mantles. Lava flows with surfaces modified by eolian erosion and deposition occur west-northwest of Apollinaris Patera at the border of the cratered equatorial uplands and southern Elysium Planitia. Nearby yardangs, for which radar observations indicate very high-rms slopes, are similar to terrestrial features of similar origin. ?? 1980.

  5. Noise characteristics of upper surface blown configurations: Analytical Studies

    NASA Technical Reports Server (NTRS)

    Reddy, N. N.; Tibbetts, J. G.; Pennock, A. P.; Tam, C. K. W.

    1978-01-01

    Noise and flow results of upper surface blown configurations were analyzed. The dominant noise source mechanisms were identified from experimental data. From far-field noise data for various geometric and operational parameters, an empirical noise prediction program was developed and evaluated by comparing predicted results with experimental data from other tests. USB aircraft compatibility studies were conducted using the described noise prediction and a cruise performance data base. A final design aircraft was selected and theory was developed for the noise from the trailing edge wake assuming it as a highly sheared layer.

  6. Micromorphology and surface characteristics of lunar dust and breccia.

    PubMed

    Cloud, P; Margolis, S V; Moorman, M; Barker, J M; Licari, G R; Krinsley, D; Barnes, V E

    1970-01-30

    Although nothing of direct biologic interest was observed in the sample studied, small shaped glass particles and glazed pits resemble objects which elsewhere have been described as fossils. These features, although nonbiological, do bear on processes of lunar weathering and outgassing. The glazed pits are impact features. Fusion of their surfaces released gases. Electron microscopy of the glasses, pits, and angular microfractured mineral grains indicates a prevalence of destructive weathering processes-thermal expansion and contraction, abrasion by by-passing particles, and, of course, impact. ous at room temperature.

  7. Serrated trailing edges for improving lift and drag characteristics of lifting surfaces

    NASA Technical Reports Server (NTRS)

    Vijgen, Paul M. H. W. (Inventor); Howard, Floyd G. (Inventor); Bushnell, Dennis M. (Inventor); Holmes, Bruce J. (Inventor)

    1992-01-01

    An improvement in the lift and drag characteristics of a lifting surface is achieved by attaching a serrated panel to the trailing edge of the lifting surface. The serrations may have a saw-tooth configuration, with a 60 degree included angle between adjacent serrations. The serrations may vary in shape and size over the span-wise length of the lifting surface, and may be positioned at fixed or adjustable deflections relative to the chord of the lifting surface.

  8. Surface Characteristics of Silicon Nanowires/Nanowalls Subjected to Octadecyltrichlorosilane Deposition and n-octadecane Coating

    NASA Astrophysics Data System (ADS)

    Yilbas, Bekir Sami; Salhi, Billel; Yousaf, Muhammad Rizwan; Al-Sulaiman, Fahad; Ali, Haider; Al-Aqeeli, Nasser

    2016-12-01

    In this study, nanowires/nanowalls were generated on a silicon wafer through a chemical etching method. Octadecyltrichlorosilane (OTS) was deposited onto the nanowire/nanowall surfaces to alter their hydrophobicity. The hydrophobic characteristics of the surfaces were further modified via a 1.5-μm-thick layer of n-octadecane coating on the OTS-deposited surface. The hydrophobic characteristics of the resulting surfaces were assessed using the sessile water droplet method. Scratch and ultraviolet (UV)-visible reflectivity tests were conducted to measure the friction coefficient and reflectivity of the surfaces. The nanowires formed were normal to the surface and uniformly extended 10.5 μm to the wafer surface. The OTS coating enhanced the hydrophobic state of the surface, and the water contact angle increased from 27° to 165°. The n-octadecane coating formed on the OTS-deposited nanowires/nanowalls altered the hydrophobic state of the surface. This study provides the first demonstration that the surface wetting characteristics change from hydrophobic to hydrophilic after melting of the n-octadecane coating. In addition, this change is reversible; i.e., the hydrophilic surface becomes hydrophobic after the n-octadecane coating solidifies at the surface, and the process again occurs in the opposite direction after the n-octadecane coating melts.

  9. Surface Characteristics of Silicon Nanowires/Nanowalls Subjected to Octadecyltrichlorosilane Deposition and n-octadecane Coating

    PubMed Central

    Yilbas, Bekir Sami; Salhi, Billel; Yousaf, Muhammad Rizwan; Al-Sulaiman, Fahad; Ali, Haider; Al-Aqeeli, Nasser

    2016-01-01

    In this study, nanowires/nanowalls were generated on a silicon wafer through a chemical etching method. Octadecyltrichlorosilane (OTS) was deposited onto the nanowire/nanowall surfaces to alter their hydrophobicity. The hydrophobic characteristics of the surfaces were further modified via a 1.5-μm-thick layer of n-octadecane coating on the OTS-deposited surface. The hydrophobic characteristics of the resulting surfaces were assessed using the sessile water droplet method. Scratch and ultraviolet (UV)-visible reflectivity tests were conducted to measure the friction coefficient and reflectivity of the surfaces. The nanowires formed were normal to the surface and uniformly extended 10.5 μm to the wafer surface. The OTS coating enhanced the hydrophobic state of the surface, and the water contact angle increased from 27° to 165°. The n-octadecane coating formed on the OTS-deposited nanowires/nanowalls altered the hydrophobic state of the surface. This study provides the first demonstration that the surface wetting characteristics change from hydrophobic to hydrophilic after melting of the n-octadecane coating. In addition, this change is reversible; i.e., the hydrophilic surface becomes hydrophobic after the n-octadecane coating solidifies at the surface, and the process again occurs in the opposite direction after the n-octadecane coating melts. PMID:27934970

  10. Phosphate filtering characteristics of a hybridized porous Al alloy prepared by surface modification.

    PubMed

    Seo, Young Ik; Lee, Young Jung; Hong, Ki Ho; Chang, Duk; Kim, Dae-Gun; Lee, Kyu Hwan; Kim, Young Do

    2010-01-15

    In this study, a porous Al alloy filter was designed for water purification systems. The combination of higher permeability for fluid flow and excellent filtering characteristics for removing pollutants is required for water purification. The filter's macropore structure was controlled by a powder metallurgical process using granulated powders for high permeability and its micropore structure was generated by alkali surface modification on the macroporous sintered body for enhanced filtration efficiency. After surface modification, the specific surface area was increased by 10 times over the as-sintered specimen. Phosphate filtering characteristic was noticeably improved by a ligand exchange between phosphate and aluminum hydroxide formed by alkali surface modification.

  11. Heterogeneous chemistry of HOBR on surfaces characteristic of atmospheric aerosols

    SciTech Connect

    Abbatt, J.P.D.

    1995-12-31

    The heterogeneous interactions of HOBr, HBr and HCl with ice and supercooled sulfuric acid solutions have been studied in a low temperatures low pressure flow tube coupled to a mass spectrometer. The heterogeneous reactions HOBr + HCl {yields} BrCl + H{sub 2}O and HOBr + HBr {yields} Br{sub 2} + H{sub 2}O have been demonstrated to proceed readily on these surfaces, and it has been shown that both HOBr and HBr are more easily partitioned to the condensed phase than their chlorine analogues. These heterogeneous reactions represent routes for the activation of halogen species in the atmosphere. In particular, the implications of this research to the depletion of stratospheric ozone after the Mt. Pinatubo volcanic eruption and to the depletion of ozone in the springtime Arctic boundary layer will be discussed.

  12. Statistical characteristics of topographic surfaces and dynamic smoothing of landscapes

    NASA Astrophysics Data System (ADS)

    Bartlett, M. S.; Laio, F.; Ridolfi, L.; Vico, G.; Porporato, A. M.

    2011-12-01

    We analyze the local statistics of topographic surfaces, including slope and aspect, as a function of scale, and explore their relations with landscape features, such as age, vegetation, and geology. These results build upon the previous work of Vico and Porporato (JGR 114, F01011, 2009), which characterized slope using generalized t-Student distributions. We find that the number of degrees of freedom of such distributions, which determines the heaviness of their tails, is linked to the age of the topographic relief of the considered regions, tending to normal distributions for very old mountain ranges. Based on these findings, and inspired by models of critical phenomena, we develop physically-based, space-time stochastic differential equations that reproduce this dynamic smoothing of rough landscapes.

  13. Influence of Surface Carburization of Machinable Ceramics on Its Pulsed Flashover Characteristics in Vacuum

    NASA Astrophysics Data System (ADS)

    Zheng, Nan; Huang, Xuezeng; Mu, Haibao; Zhang, Guanjun

    2011-12-01

    For pulsed power devices, surface flashover phenomena across solid insulators greatly restrict their overall performance. In recent decades, much attention has been paid on enhancing the surface electric withstanding strength of insulators, and it is found that surface treatment of material is useful to improve the surface flashover voltage. The carburization treatment is employed to modify the surface components of newly-developed machinable ceramics (MC) materials. A series of MC samples with different glucose solution concentration (0%, 10%, 20%, 30% and 40%) are prepared by chemical reactions for surface carburization modification, and their surface flashover characteristics are investigated under pulsed voltage in vacuum. It is found that the surface carburization treatment greatly modifies the surface resistivity of MCs and hence the flashover behaviors. Based on the reduction of surface resistivity and the secondary electron emission avalanche (SEEA) theory, the adjustment of flashover withstanding ability can be reasonably explained.

  14. Design, Surface Treatment, Cellular Plating, and Culturing of Modular Neuronal Networks Composed of Functionally Inter-connected Circuits.

    PubMed

    Kanner, Sivan; Bisio, Marta; Cohen, Gilad; Goldin, Miri; Tedesco, Marieteresa; Hanein, Yael; Ben-Jacob, Eshel; Barzilai, Ari; Chiappalone, Michela; Bonifazi, Paolo

    2015-04-15

    The brain operates through the coordinated activation and the dynamic communication of neuronal assemblies. A major open question is how a vast repertoire of dynamical motifs, which underlie most diverse brain functions, can emerge out of a fixed topological and modular organization of brain circuits. Compared to in vivo studies of neuronal circuits which present intrinsic experimental difficulties, in vitro preparations offer a much larger possibility to manipulate and probe the structural, dynamical and chemical properties of experimental neuronal systems. This work describes an in vitro experimental methodology which allows growing of modular networks composed by spatially distinct, functionally interconnected neuronal assemblies. The protocol allows controlling the two-dimensional (2D) architecture of the neuronal network at different levels of topological complexity. A desired network patterning can be achieved both on regular cover slips and substrate embedded micro electrode arrays. Micromachined structures are embossed on a silicon wafer and used to create biocompatible polymeric stencils, which incorporate the negative features of the desired network architecture. The stencils are placed on the culturing substrates during the surface coating procedure with a molecular layer for promoting cellular adhesion. After removal of the stencils, neurons are plated and they spontaneously redirected to the coated areas. By decreasing the inter-compartment distance, it is possible to obtain either isolated or interconnected neuronal circuits. To promote cell survival, cells are co-cultured with a supporting neuronal network which is located at the periphery of the culture dish. Electrophysiological and optical recordings of the activity of modular networks obtained respectively by using substrate embedded micro electrode arrays and calcium imaging are presented. While each module shows spontaneous global synchronizations, the occurrence of inter-module synchronization

  15. Fabrication and condensation characteristics of metallic superhydrophobic surface with hierarchical micro-nano structures

    NASA Astrophysics Data System (ADS)

    Chu, Fuqiang; Wu, Xiaomin

    2016-05-01

    Metallic superhydrophobic surfaces have various applications in aerospace, refrigeration and other engineering fields due to their excellent water repellent characteristics. This study considers a simple but widely applicable fabrication method using a two simultaneous chemical reactions method to prepare the acid-salt mixed solutions to process the metal surfaces with surface deposition and surface etching to construct hierarchical micro-nano structures on the surface and then modify the surface with low surface-energy materials. Al-based and Cu-based superhydrophobic surfaces were fabricated using this method. The Al-based superhydrophobic surface had a water contact angle of 164° with hierarchical micro-nano structures similar to the lotus leaves. The Cu-based surface had a water contact angle of 157° with moss-like hierarchical micro-nano structures. Droplet condensation experiments were also performed on these two superhydrophobic surfaces to investigate their condensation characteristics. The results show that the Al-based superhydrophobic surface has lower droplet density, higher droplet jumping probability, slower droplet growth rate and lower surface coverage due to the more structured hierarchical structures.

  16. Surface characteristics and evolution of debris covered glaciers

    NASA Astrophysics Data System (ADS)

    Mölg, Nico; Vieli, Andreas; Bolch, Tobias; Bauder, Andreas; Bhattacharya, Atanu

    2016-04-01

    Global climate change has led to increasing glacier retreat in most parts of the world. However, many heavily debris-covered glaciers have shown much smaller recession rates than their clean-ice neighbours. This can be attributed to the insulation effect of the supraglacial debris. Remote-sensing based investigations revealed that recent mass balances of debris-covered glaciers are equally negative. This fact is partly due to enhanced melting at supra-glacial lakes and ice cliffs but can also be caused by reduced mass flux. In this context, insufficient process understanding constitutes a major challenge for large scale glacier change assessment and modelling. In this project, we aim at better understanding the evolution of glaciers in connection with changes in supra-glacial debris coverage. It is performed on Zmutt Glacier in Matter valley in Switzerland and on Gangotri Glacier in Garwhal Himalaya in India. Changes in glacier length, area, debris coverage, and surface elevation were compiled based on topographic maps, oblique photos, aerial and satellite orthoimages, digital terrain models (DTMs), and glacier monitoring data for a 50 (Gangotri) and 120 (Zmutt) year period, respectively. The subsequent analysis revealed that Zmutt Glacier has been in a slow but almost continuous retreating state since the end of the 19th century and showed a clear reduction in glacier area and volume. Similarly, Gangotri Glacier has retreated and, to a smaller degree, lost volume. However, the change in glacier length and area is clearly smaller than for other nearby, less debris-covered or debris-free glaciers. This fact is attributed to the larger debris-covered area that has steadily increased. Further in the project, this data will serve as an important input and validation for the envisaged 3D flow modelling and, hence, will contribute to the understanding of the development of glaciers and debris-covered ice in a period of fast climatic changes.

  17. Evaluating the Influence of Surface and Precipitation Characteristics on TMI and GMI Precipitation Retrievals.

    NASA Astrophysics Data System (ADS)

    Carr, N.; Kirstetter, P.; Hong, Y.; Gourley, J. J.; Ferraro, R. R.; Kummerow, C. D.; Petersen, W. A.; Schwaller, M.; Wang, N. Y.

    2014-12-01

    To evaluate the influence of surface and precipitation characteristics on Passive microwave (PMW) precipitation retrievals, precipitation products obtained from both the TRMM Microwave Imager (TMI) and the GPM Microwave Imager (GMI) were evaluated relative to independent high-resolution reference precipitation products obtained using the NOAA/NSSL ground radar-based Multi-Radar Multi-Sensor (MRMS) system. Specifically the ability of each sensor to detect, classify, and quantify instantaneous surface precipitation at its native pixel resolution is examined and linked to surface and precipitation characteristics. Surface characteristics were derived optically using NASA's Moderate Resolution Imaging Spectroradiometer (MODIS). Precipitation mesoscale characteristics such as convective-stratiform classification and spatial structure were obtained from the high-resolution reference data. The quality of both PMW sensors' retrievals varied considerably with surface characteristics; both sensors displayed decreased detection and quantification statistics over sparsely vegetated and dry surfaces. Similarly, the quality of the precipitation retrievals was affected by precipitation characteristics and high relative errors were evident in isolated and small-scale precipitation events as well as in mixed stratiform-convective events. The error characteristics of the two sensors also differed in several significant aspects, namely TMI tended to overestimate precipitation relative to the reference, while GMI underestimated precipitation. The influence of the precipitation and surface characteristics was less evident in the more sophisticated GMI retrievals. An additional outcome of the study was the adaptation of the comparison framework between space and ground precipitation estimates to accommodate the new probabilistic features of the GPM-era PMW precipitation retrievals.

  18. Optical device for measuring a surface characteristic of an object by multi-color interferometry

    NASA Technical Reports Server (NTRS)

    Meyer, William V. (Inventor); Smart, Anthony E. (Inventor)

    2001-01-01

    An interferometer having a light beam source that produces a plurality of separate and distinct wavelengths of light. Optic fibers are used to transport the wavelengths of light toward an object surface and to allow light reflected from the object to pass through a polarizer to improve the polarization ratio of the reflected light to determine a characteristic of the object surface.

  19. Biochemical and cellular characteristics of the four splice variants of protein kinase CK1alpha from zebrafish (Danio rerio).

    PubMed

    Burzio, Veronica; Antonelli, Marcelo; Allende, Catherine C; Allende, Jorge E

    2002-01-01

    Protein kinase CK1 (previously known as casein kinase I) conforms to a subgroup of the great protein kinase family found in eukaryotic organisms. The CK1 subgroup of vertebrates contains seven members known as alpha, beta, gamma1, gamma2, gamma3, delta, and epsilon. The CK1alpha gene can generate four variants (CK1alpha, CK1alphaS, CK1alphaL, and CK1alphaLS) through alternate splicing, characterized by the presence or absence of two additional coding sequences. Exon "L" encodes a 28-amino acid stretch that is inserted after lysine 152, in the center of the catalytic domain. The "S" insert encodes 12 amino acid residues and is located close to the carboxyl terminus of the protein. This work reports some biochemical and cellular properties of the four CK1alpha variants found to be expressed in zebrafish (Danio rerio). The results obtained indicate that the presence of the "L" insert affects several biochemical properties of CK1alpha: (a) it increases the apparent Km for ATP twofold, from approximately 30 to approximately 60 microM; (b) it decreases the sensitivity to the CKI-7 inhibitor, raising the I50 values from 113 to approximately 230 microM; (c) it greatly decreases the heat stability of the enzyme at 40 degrees C. In addition, the insertion of the "L" fragment exerts very important effects on some cellular properties of the enzyme. CK1alphaL concentrates in the cell nucleus, excluding nucleoli, while the CK1alpha variant is predominantly cytoplasmic, although some presence is observed in the nucleus. This finding supports the thesis that the basic-rich region found in the "L" insert acts as a nuclear localization signal. The "L" insert-containing variant was also found to be more rapidly degraded (half-life of 100 min) than the CK1alpha variant (half-life of 400 min) in transfected Cos-7 cells.

  20. The Effects of Surface Reconstruction and Electron-Positron Correlation on the Annihilation Characteristics of Positrons Trapped at Semiconductor Surfaces

    SciTech Connect

    Fazleev, N. G.; Jung, E.; Weiss, A. H.

    2009-03-10

    Experimental positron annihilation induced Auger electron spectroscopy (PAES) data from Ge(100) and Ge(111) surfaces display several strong Auger peaks corresponding to M{sub 4,5}N{sub 1}N{sub 2,3}, M{sub 2,3}M{sub 4,5}M{sub 4,5}, M{sub 2,3}M{sub 4,5}V, and M{sub 1}M{sub 4,5}M{sub 4,5} Auger transitions. The integrated peak intensities of Auger transitions have been used to obtain experimental annihilation probabilities for the Ge 3d and 3p core electrons. The experimental data were analyzed by performing theoretical studies of the effects of surface reconstructions and electron-positron correlations on image potential induced surface states and annihilation characteristics of positrons trapped at the reconstructed Ge(100) and Ge(111) surfaces. Calculations of positron surface states and annihilation characteristics have been performed for Ge(100) surface with (2x1), (2x2), and (4x2) reconstructions, and for Ge(111) surface with c(2x8) reconstruction. Estimates of the positron binding energy and annihilation characteristics reveal their sensitivity to the specific atomic structure of the topmost layers of the semiconductor and to the approximations used to describe electron-positron correlations. The results of these theoretical studies are compared with the ones obtained for the reconstructed Si(100)-(2x1) and Si(111)-(7x7) surfaces.

  1. Cellular Uptake and Cytotoxicity of β-Lactoglobulin Nanoparticles: The Effects of Particle Size and Surface Charge

    PubMed Central

    Ha, Ho-Kyung; Kim, Jin Wook; Lee, Mee-Ryung; Jun, Woojin; Lee, Won-Jae

    2015-01-01

    It is necessary to understand the cellular uptake and cytotoxicity of food-grade delivery systems, such as β-lactoglobulin (β-lg) nanoparticles, for the application of bioactive compounds to functional foods. The objectives of this study were to investigate the relationships between the physicochemical properties of β-lg nanoparticles, such as particle size and zeta-potential value, and their cellular uptakes and cytotoxicity in Caco-2 cells. Physicochemical properties of β-lg nanoparticles were evaluated using particle size analyzer. Flow cytometry and confocal laser scanning microscopy were used to investigate cellular uptake and cytotoxicity of β-lg nanoparticles. The β-lg nanoparticles with various particle sizes (98 to 192 nm) and zeta-potential values (−14.8 to −17.6 mV) were successfully formed. A decrease in heating temperature from 70°C to 60°C resulted in a decrease in the particle size and an increase in the zeta-potential value of β-lg nanoparticles. Non-cytotoxicity was observed in Caco-2 cells treated with β-lg nanoparticles. There was an increase in cellular uptake of β-lg nanoparticles with a decrease in particle size and an increase in zeta-potential value. Cellular uptake β-lg nanoparticles was negatively correlated with particle size and positively correlated with zeta-potential value. Therefore, these results suggest that the particle size and zeta-potential value of β-lg nanoparticles play an important role in the cellular uptake. The β-lg nanoparticles can be used as a delivery system in foods due to its high cellular uptake and non-cytotoxicity. PMID:25656189

  2. Toxicity and cellular uptake of gold nanorods in vascular endothelium and smooth muscles of isolated rat blood vessel: importance of surface modification.

    PubMed

    Alkilany, Alaaldin M; Shatanawi, Alia; Kurtz, Timothy; Caldwell, Ruth B; Caldwell, R William

    2012-04-23

    Gold nanorods (GNRs) have promising applications in drug delivery and cancer treatment and are generally administered via direct injection into the circulation. Thus it is necessary to evaluate their potential adverse effects on blood vessels. Herein, GNRs with various surface modifications are used to evaluate the toxicity and cellular uptake of GNRs into vascular endothelial and smooth muscle cells of isolated rat aortic rings. Surfactant-capped GNRs are synthesized and either coated with polyelectrolyte (PE) to prepare PE-GNRs, or modified with thiolated polyethylene glycol (PEG) to prepare PEG-GNRs. Using toxicity assays, small-vessel myography, fluorescence microscopy, and electron microscopy, it is shown that therapeutic concentrations of PE-GNRs but not PEG-GNRs are toxic to the vascular endothelium, which leads to an impaired relaxation function of aortic rings. However, no toxicity to smooth muscles is observed. Moreover, electron microscopy analysis confirms the cellular uptake of PE-GNRs but not PEG-GNRs into the endothelium of exposed aortic rings. The difference in toxicity and cellular uptake of PE-GNRs versus PEG-GNRs is explained and linked to free surfactant molecules and protein adsorption, respectively. The results indicate that toxicity and cellular uptake in the vascular endothelium in blood vessels are potential adverse effects of systemically administered GNR solutions, which can be prevented by appropriate surface functionalization.

  3. Bioactivity and Surface Characteristics of Titanium Implants Following Various Surface Treatments: An In Vitro Study.

    PubMed

    Kumar K, Aswini; Bhatt, Vinaya; Balakrishnan, Manilal; Hashem, Mohamed; Vellappally, Sajith; Aziz A Al Kheraif, Abdul; Halawany, Hassan Suliman; Abraham, Nimmi Biju; Jacob, Vimal; Anil, Sukumaran

    2015-10-01

    This study compared the surface topography, hydrophilicity, and bioactivity of titanium implants after 3 different surface treatments (sandblasting and acid etching, modified sandblasting and acid etching, and thermal oxidation) with those of machined implants. One hundred indigenously manufactured threaded titanium implants were subjected to 3 methods of surface treatment. The surface roughness of the nontreated (Group A) and treated samples (Groups B through D) was evaluated with a scanning electron microscope (SEM) and profilometer. The wettability was visually examined using a colored dye solution. The calcium ions attached to the implant surface after immersing in simulated body fluid (SBF) were assessed on days 1, 2, and 7 with an atomic electron spectroscope. The data were analyzed statistically. The SBF test allowed the precipitation of a calcium phosphate layer on all surface-treated samples, as evidenced in the SEM analysis. A significantly higher amount of calcium ions and increased wettability were achieved in the thermally oxidized samples. The mean roughness was significantly lower in Group A (0.85 ± 0.07) compared to Group B (1.35 ± 0.17), Group C (1.40 ± 0.14), and Group D (1.36 ± 0.18). The observations from this in vitro study indicated that surface treatment of titanium improved the bioactivity. Moreover, results identified the implants that were sandblasted, acid etched, and then oxidized attracted more calcium ions.

  4. Recontextualising Cellular Respiration in Upper Secondary Biology Education. Characteristics and Practicability of a Learning and Teaching Strategy

    ERIC Educational Resources Information Center

    Wierdsma, Menno; Knippels, Marie-Christine; van Oers, Bert; Boersma, Kerst

    2016-01-01

    Since concepts may have different meanings in different contexts, students have to learn to recontextualise them, i.e. to adapt their meanings to a new context. It is unclear, however, what characteristics a learning and teaching strategy for recontextualising should have. The study aims to develop such a learning and teaching strategy for…

  5. Secondary electron emission characteristics of ion-textured copper and high-purity isotropic graphite surfaces

    NASA Technical Reports Server (NTRS)

    Curren, A. N.; Jensen, K. A.

    1984-01-01

    Experimentally determined values of true secondary electron emission and relative values of reflected primary electron yield for untreated and ion textured oxygen free high conductivity copper and untreated and ion textured high purity isotropic graphite surfaces are presented for a range of primary electron beam energies and beam impingement angles. This investigation was conducted to provide information that would improve the efficiency of multistage depressed collectors (MDC's) for microwave amplifier traveling wave tubes in space communications and aircraft applications. For high efficiency, MDC electrode surfaces must have low secondary electron emission characteristics. Although copper is a commonly used material for MDC electrodes, it exhibits relatively high levels of secondary electron emission if its surface is not treated for emission control. Recent studies demonstrated that high purity isotropic graphite is a promising material for MDC electrodes, particularly with ion textured surfaces. The materials were tested at primary electron beam energies of 200 to 2000 eV and at direct (0 deg) to near grazing (85 deg) beam impingement angles. True secondary electron emission and relative reflected primary electron yield characteristics of the ion textured surfaces were compared with each other and with those of untreated surfaces of the same materials. Both the untreated and ion textured graphite surfaces and the ion treated copper surface exhibited sharply reduced secondary electron emission characteristics relative to those of untreated copper. The ion treated graphite surface yielded the lowest emission levels.

  6. The influence of surface charge on serum protein interaction and cellular uptake: studies with dendritic polyglycerols and dendritic polyglycerol-coated gold nanoparticles.

    PubMed

    Bewersdorff, Tony; Vonnemann, Jonathan; Kanik, Asiye; Haag, Rainer; Haase, Andrea

    2017-01-01

    Nanoparticles (NPs) have gained huge interest in the medical field, in particular for drug delivery purposes. However, binding of proteins often leads to fast NP uptake and rapid clearance, thereby hampering medical applications. Thus, it is essential to determine and control the bio-nano interface. This study investigated the serum protein interactions of dendritic polyglycerols (dPGs), which are promising drug delivery candidates by means of two dimensional gel electrophoresis (2DE) in combination with mass spectrometry. In order to investigate the influence of surface charge, sulfated (sulfated dendritic polyglycerol [dPGS]) and non-sulfated (dPGOH) surfaces were applied, which were synthesized on a gold core allowing for easier separation from unbound biomolecules through centrifugation. Furthermore, two different sizes for dPGS were included. Although size had only a minor influence, considerable differences were detected in protein affinity for dPGS versus dPGOH surfaces, with dPGOH binding much less proteins. Cellular uptake into human CD14(+) monocytes was analyzed by flow cytometry, and dPGOH was taken up to a much lower extent compared to dPGS. By using a pull-down approach, possible cellular interaction partners of serum pre-incubated dPGS-Au20 NPs from the membrane fraction of THP-1 cells could be identified such as for instance the transferrin receptor or an integrin. Clathrin-mediated endocytosis was further investigated using chlorpromazine as an inhibitor, which resulted in a 50% decrease of the cellular uptake of dPGS. This study could confirm the influence of surface charge on protein interactions and cellular uptake of dPGS. Furthermore, the approach allowed for the identification of possible uptake receptors and insights into the uptake mechanism.

  7. The influence of surface charge on serum protein interaction and cellular uptake: studies with dendritic polyglycerols and dendritic polyglycerol-coated gold nanoparticles

    PubMed Central

    Bewersdorff, Tony; Vonnemann, Jonathan; Kanik, Asiye; Haag, Rainer; Haase, Andrea

    2017-01-01

    Nanoparticles (NPs) have gained huge interest in the medical field, in particular for drug delivery purposes. However, binding of proteins often leads to fast NP uptake and rapid clearance, thereby hampering medical applications. Thus, it is essential to determine and control the bio–nano interface. This study investigated the serum protein interactions of dendritic polyglycerols (dPGs), which are promising drug delivery candidates by means of two dimensional gel electrophoresis (2DE) in combination with mass spectrometry. In order to investigate the influence of surface charge, sulfated (sulfated dendritic polyglycerol [dPGS]) and non-sulfated (dPGOH) surfaces were applied, which were synthesized on a gold core allowing for easier separation from unbound biomolecules through centrifugation. Furthermore, two different sizes for dPGS were included. Although size had only a minor influence, considerable differences were detected in protein affinity for dPGS versus dPGOH surfaces, with dPGOH binding much less proteins. Cellular uptake into human CD14+ monocytes was analyzed by flow cytometry, and dPGOH was taken up to a much lower extent compared to dPGS. By using a pull-down approach, possible cellular interaction partners of serum pre-incubated dPGS-Au20 NPs from the membrane fraction of THP-1 cells could be identified such as for instance the transferrin receptor or an integrin. Clathrin-mediated endocytosis was further investigated using chlorpromazine as an inhibitor, which resulted in a 50% decrease of the cellular uptake of dPGS. This study could confirm the influence of surface charge on protein interactions and cellular uptake of dPGS. Furthermore, the approach allowed for the identification of possible uptake receptors and insights into the uptake mechanism. PMID:28352171

  8. Vincristine and ɛ-viniferine-loaded PLGA-b-PEG nanoparticles: pharmaceutical characteristics, cellular uptake and cytotoxicity.

    PubMed

    Öğünç, Yüksel; Demirel, Müzeyyen; Yakar, Arzu; İncesu, Zerrin

    2017-02-02

    The objective of this study was to prepare the ɛ-viniferine and vincristine-loaded PLGA-b-PEG nanoparticle and to investigate advantages of these formulations on the cytotoxicity of HepG2 cells. Prepared nanoparticle has shown a homogeneous distribution with 113 ± 0.43 nm particle size and 0.323 ± 0.01 polydispersity index. Zeta potential was determined as -35.03 ± 1.0 mV. The drug-loading percentages were 6.01 ± 0.23 and 2.01 ± 0.07 for ɛ-viniferine and vincristine, respectively. The cellular uptake efficiency of coumarin-6-loaded nanoparticles was increased up to 87.8% after 4 h. Nanoparticles loaded with high concentrations of both drugs showed a cytotoxic effect on HepG2 cells, having the percentage of cell viability of between 43.23% and 47.37%. Unfortunately, the percentage of apoptotic cells after treated with drugs-loaded nanaoparticles (10.93%) was similar to free forms of drugs (12.1%) that might be due to low ɛ-viniferine release in biological pH at 24 h.

  9. Lubrication characteristics of nano-oil with different degrees of surface hardness of sliding members.

    PubMed

    Ku, Boncheol; Han, Youngcheol; Lee, Kwangho; Choi, Youngmin; Koo, Bonyoung; Hwang, Yujin; Lee, Jaekeun

    2011-01-01

    In this study, the lubrication characteristics of sliding members were compared with the changes in the hardness of friction surfaces and the application of nano-oil. The materials of the specimens were gray cast iron (AISI 35 and AISI 60) and nickel chromium molybdenum steel (AISI 4320). The friction coefficients and the temperature variations of the frictional surfaces were measured with a disk-on-disk tribotester under a fixed rotation speed. The friction surfaces were observed with a scanning electron microscope (SEM). The friction coefficients of the plate surface increased as the hardness difference increased. The friction coefficient after the lubrication with nano-oil was less than that after lubrication with mineral oil. This is because a spherical nanoparticle plays the role of a tiny ball bearing between the frictional surfaces that improve the lubrication characteristics.

  10. Laser treatment of a neodymium magnet and analysis of surface characteristics

    NASA Astrophysics Data System (ADS)

    Yilbas, B. S.; Ali, H.; Rizwan, M.; Kassas, M.

    2016-08-01

    Laser treatment of neodymium magnet (Nd2Fe14B) surface is carried out under the high pressure nitrogen assisting gas. A thin carbon film containing 12% WC carbide particles with 400 nm sizes are formed at the surface prior to the laser treatment process. Morphological and metallurgical changes in the laser treated layer are examined using the analytical tools. The corrosion resistance of the laser treated surface is analyzed incorporating the potentiodynamic tests carried out in 0.05 M NaCl+0.1 M H2SO4 solution. The friction coefficient of the laser treated surface is measured using the micro-scratch tester. The wetting characteristics of the treated surface are assessed incorporating the sessile water drop measurements. It is found that a dense layer consisting of fine size grains and WC particles is formed in the surface region of the laser treated layer. Corrosion resistance of the surface improves significantly after the laser treatment process. Friction coefficient of laser treated surface is lower than that of the as received surface. Laser treatment results in superhydrophobic characteristics at the substrate surface. The formation of hematite and grain size variation in the treated layer slightly lowers the magnetic strength of the laser treated workpiece.

  11. Relationship between powder surface characteristics and viscoelastic properties of powder-filled semisolids.

    PubMed

    Radebaugh, G W; Simonelli, A P

    1985-01-01

    The viscoelastic properties of dispersions of powdered zinc oxide in anhydrous lanolin and colloidal sulfur in anhydrous lanolin were characterized by dynamic mechanical testing. The elastic shear modulus, G', viscous shear modulus, G", and loss tangent (damping), tan delta, were determined as a function of shear frequency, v, temperature, T, and volume fraction of powder, phi 2. A priori, it might be expected that zinc oxide and colloidal sulfur would elicit different viscoelastic properties due to their contrasting surface characteristics; zinc oxide has a hydrophilic surface and colloidal sulfur has a hydrophobic surface. Even though constitutive mathematical models, derived to predict the mechanical behavior of solid-filled polymeric materials, were not designed to account for differences in surface characteristics of the filler, the findings of these experiments show that these models are useful in explaining the differences in viscoelastic behavior of powder-filled semisolids due to surface characteristics of the filler. One model of particular value was the Kerner equation. With it, mechanisms were postulated for zinc oxide-zinc oxide interactions, sulfur-sulfur interactions, zinc oxide-anhydrous lanolin interactions, and sulfur-anhydrous lanolin interactions, within dispersions as a function of nu, T, and phi 2. In addition, damping was used to further identify the influence of temperature. Data obtained from three temperatures, where anhydrous lanolin exists in three different structural states, shows that the influence of the powder on damping is not only determined by the surface characteristics of the powder but also the structural state of anhydrous lanolin.

  12. Enhancing the Representation of Subgrid Land Surface Characteristics in Land Surface Models

    SciTech Connect

    Ke, Yinghai; Leung, Lai-Yung R.; Huang, Maoyi; Li, Hongyi

    2013-09-27

    Land surface heterogeneity has long been recognized and increasingly incorporated in the land surface modelling. In most existing land surface models, the spatial variability of surface cover is represented as subgrid composition of multiple surface cover types. In this study, we developed a new subgrid classification method (SGC) that accounts for the topographic variability of the vegetation cover. Each model grid cell was represented with a number of elevation classes and each elevation class was further described by a number of vegetation types. The numbers of elevation classes and vegetation types were variable and optimized for each model grid so that the spatial variability of both elevation and vegetation can be reasonably explained given a pre-determined total number of classes. The subgrid structure of the Community Land Model (CLM) was used as an example to illustrate the newly developed method in this study. With similar computational burden as the current subgrid vegetation representation in CLM, the new method is able to explain at least 80% of the total subgrid PFTs and greatly reduced the variations of elevation within each subgrid class compared to the baseline method where a single elevation class is assigned to each subgrid PFT. The new method was also evaluated against two other subgrid methods (SGC1 and SGC2) that assigned fixed numbers of elevation and vegetation classes for each model grid with different perspectives of surface cover classification. Implemented at five model resolutions (0.1°, 0.25°, 0.5°, 1.0° and 2.0°) with three maximum-allowed total number of classes N_class of 24, 18 and 12 representing different computational burdens over the North America (NA) continent, the new method showed variable performances compared to the SGC1 and SGC2 methods. However, the advantage of the SGC method over the other two methods clearly emerged at coarser model resolutions and with moderate computational intensity (N_class = 18) as it

  13. Effects of storage medium and UV photofunctionalization on time-related changes of titanium surface characteristics and biocompatibility.

    PubMed

    Shen, Jian-Wei; Chen, Yun; Yang, Guo-Li; Wang, Xiao-Xiang; He, Fu-Ming; Wang, Hui-Ming

    2016-07-01

    Storage in aqueous solution and ultraviolet (UV) photofunctionalization are two applicable methods to overcome the biological aging and increase the bioactivity of titanium. As information regarding the combined effects of storage medium and UV photofunctionalization has never been found in published literatures, this study focused on whether appropriate storage methods and UV photofunctionalization have synergistic effects on the biological properties of aged titanium surfaces. Titanium plates and discs were sandblasted and acid etched and then further prepared in five different modes as using different storage mediums (air or dH2 O) for 4 weeks and then with or without UV treatment. The surface characteristics were evaluated with scanning electron microscopy, contact angle measurements, and X-ray photoelectron spectroscopy. MC3T3-E1 cells were cultured on the surfaces, and cellular morphology, proliferation, alkaline phosphatase activity, and osteocalcin release were evaluated. The results showed that nanostructures were observed on water-stored titanium surfaces with a size of about 15 × 20 nm(2) . UV treatment was effective to remove the hydrocarbon contamination on titanium surfaces stored in either air or water. UV photofunctionalization further enhanced the already increased bioactivity of modSLA on initial cell attachment, proliferation, alkaline phosphatase activity, and osteocalcin release. Overall, UV photofunctionalization was effective in further enhancing the already increased bioactivity by using dH2 O as storage medium, and the effect of UV treatment was much more overwhelming than that of the storage medium. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 932-940, 2016.

  14. Biochar production from coffee residues: Optimization of surface characteristics and sorptive behavior

    NASA Astrophysics Data System (ADS)

    Fotopoulou, Kalliopi; Manariotis, Ioannis D.; Karapanagioti, Hrissi K.

    2015-04-01

    Biochar with high surface area is a promising sorbent for environmental remediation and is produced by heating biomass in an oxygen-limited environment. Knowing the surface characteristics increases our understanding of biochar interactions with pollutants. The hypothesis of the present study is that by controlling pyrolysis conditions, the surface characteristics and subsequently the sorption behavior of produced biochars can be optimized. Coffee residues were dried overnight at 50oC and then pyrolized into a gradient furnace at 850oC. Different solid/oxygen ratios during pyrolysis were tested as well as the up scaling of the process. The biochars produced were systematically characterized for their surface characteristics such as BET surface area, open surface area, pore and micropore volume, and average pore size. The effect of pyrolysis on the biochar suspension pH was examined with the mass addition technique that involves the addition of increasing amounts of the biochar to bottles containing 0.1 M NaNO3. FTIR analysis was used in order to determine the functional groups of the coffee residue and of the biochars. The macrostructure of the biochars was visualized by Scanning Electron Microscopy (SEM). Total Carbon (TC) in the samples was determined by Carlo Erba Elemental Analyzer CHNS, EO 1108 after calibration with standard samples. The sorption behavior of produced biochars was tested with two different pollutants (Hg(II), phenanthrene) using batch reactors with the same initial single-compound solution and the same mass of coffee residue and different biochars. The biochars produced exhibited a wide range of surface area from 21 to 770 m2/g and open surface area due to macropores from 21 to 65 m2/g. This suggests that the surface area in the biochars with high surface area results from the formation of pores. Actually for the biochar with the highest surface area, it was calculated that up to 90

  15. The Study of Cellular and Molecular Physiological Characteristics of Sperm in Men Living in the Aral Sea Region

    PubMed Central

    Kultanov, Berikbay Z.; Dosmagambetova, Raushan S.; Ivasenko, Svetlana A.; Tatina, Yelena S.; Kelmyalene, Assel A.; Assenova, Lyazzat H.

    2016-01-01

    BACKGROUND: Extreme environmental situation in the Aral crisis has caused a massive chemical pollution of the territory for decades with high doses of pesticides, herbicides. Discharge of industrial waste into the rivers that feed the Aral Sea has lead to the development of various pathological processes in the human body, as well as disruption of reproductive function in young men. AIM: To evaluate the performance of molecular cellular changes in the sperm of men under the influence of dust and salt aerosols in Aral Sea region. MATERIAL AND METHODS: Clinical and laboratory studies were conducted in men 5 settlements (Aralsk-city, v. Aiteke-Bi, v. Zhalagash, v. Zhusaly, v. Shieli). We have studied male ejaculate obtained after 4-5 days of abstinence, and placed it in a warm tube with a glass stopper. On the investigation proceeded ejaculate within 20-30 minutes after its preparation, during which time he was subjected to liquefaction. Isolation and quantification of ASF, RNA, DNA, and determining the fraction of histones in sperm was performed by the method of Markusheva and Savina. RESULTS: It was found that the value of ASF in the semen of men living in the zone of ecological disaster higher compared with the values of parameters in men living in the area of environmental crisis, and this trend is observed in all age groups. The study of circulating extracellular DNA and RNA in the sperm of men registered their decline with a corresponding increase of acid precursors that can be attributed to the degradation of nucleic acids under the influence of negative factors in the complex area of ecological trouble. Also, according to a study in men residing in the areas of environmental catastrophe at the age of 18-29 years, found an increased content of the H1 histone H2A lower total fraction, H3, H4 - and a sharp increase in histone H2B content - histones. CONCLUSIONS: Men living in environmentally disadvantaged areas of Kyzylorda region under the influence of dust and

  16. [Surface physicochemical and fractal characteristics of sediments in desilting basin from Yellow River diversion reservoir].

    PubMed

    Hu, Kang-Bo; Wang, Yi-Li; Li, Jun-Qing; Gui, Ping; Jiang, Yan-Ling

    2011-07-01

    Surface morphology and pore surface fractal characteristics of the sediment in the desilting basin of Queshan Reservoir were studied. Six sediment samples were collected and particle size, morphology, pore structure and fractal characteristics, surface elements distribution were analyzed as well. The objectives of this study were to investigate the reason for the differences among the pore surface fractal dimensions and fractal scales on the basis of different models, and discuss the effect of surface morphology of these sediment particles on their surface elements distribution. The results showed that these sediment particles with average diameter of 18-83 microm were mainly composed of clay, silt and fine sand. Their complex surface morphology and pore size distribution were reflected by wide range of the BET surface area (8.248-31.60 m2/g), average pore diameter (3.977-7.850 nm) and pore-size distribution (1.870-60.78 nm). Although the pore surface fractal dimensions (D(s)), based on fractal FHH or thermodynamic models, were 2.67-2.89, and their fractal scales generally ranged from several nanometers to tens of nanometers, the differences were still observed in D(s) values calculated from above two models because of inhomogeneity in surface pore size distribution. Therefore, the D(s) based on pore-size distribution were 2.12-2.60, these values close to D(s) calculated from fractal FHH models revealed that pore-size distribution could contribute significantly to D(s) calculation. In addition, the heterogeneous surface adsorption sites of these sediment particles caused by much complex surface morphology had strong influence on the each element distribution on the particle surface.

  17. Surface elastic modulus of barnacle adhesive and release characteristics from silicone surfaces.

    PubMed

    Sun, Yujie; Guo, Senli; Walker, Gilbert C; Kavanagh, Christopher J; Swain, Geoffrey W

    2004-12-01

    The properties of barnacle adhesive on silicone surfaces were studied by AFM indentation, imaging, and other tests and compared to the barnacle shear adhesion strength. A multilayered structure of barnacle adhesive plaque is proposed based on layered modulus regions measured by AFM indentation. The fracture of barnacles from PDMS surfaces was found to include both interfacial and cohesive failure of barnacle adhesive plaque, as determined by protein staining of the substratum after forced barnacle release from the substrate. Data for freshly released barnacles showed that there was a strong correlation between the mean Young's modulus of the outermost (softest) adhesive layer (E<0.3 MPa) and the shear strength of adhesion, but no correlation for other higher modulus regions. Linear, quadratic, and Griffith's failure criterion (based on rough estimate of crack length) regressions were used in the fit, and showed significance.

  18. Identification of subpopulations with characteristics of mesenchymal progenitor cells from human osteoarthritic cartilage using triple staining for cell surface markers

    PubMed Central

    Fickert, Stefan; Fiedler, Jörg; Brenner, Rolf E

    2004-01-01

    We first identified and isolated cellular subpopulations with characteristics of mesenchymal progenitor cells (MPCs) in osteoarthritic cartilage using fluorescence-activated cell sorting (FACS). Cells from osteoarthritic cartilage were enzymatically isolated and analyzed directly or after culture expansion over several passages by FACS using various combinations of surface markers that have been identified on human MPCs (CD9, CD44, CD54, CD90, CD166). Culture expanded cells combined and the subpopulation derived from initially sorted CD9+, CD90+, CD166+ cells were tested for their osteogenic, adipogenic and chondrogenic potential using established differentiation protocols. The differentiation was analyzed by immunohistochemistry and by RT-PCR for the expression of lineage related marker genes. Using FACS analysis we found that various triple combinations of CD9, CD44, CD54, CD90 and CD166 positive cells within osteoarthritic cartilage account for 2–12% of the total population. After adhesion and cultivation their relative amount was markedly higher, with levels between 24% and 48%. Culture expanded cells combined and the initially sorted CD9/CD90/CD166 triple positive subpopulation had multipotency for chondrogenic, osteogenic and adipogenic differentiation. In conclusion, human osteoarthritic cartilage contains cells with characteristics of MPCs. Their relative enrichment during in vitro cultivation and the ability of cell sorting to obtain more homogeneous populations offer interesting perspectives for future studies on the activation of regenerative processes within osteoarthritic joints. PMID:15380042

  19. Identification card and codification of the chemical and morphological characteristics of 14 dental implant surfaces.

    PubMed

    Dohan Ehrenfest, David M; Vazquez, Lydia; Park, Yeong-Joon; Sammartino, Gilberto; Bernard, Jean-Pierre

    2011-10-01

    Dental implants are commonly used in daily practice; however, most surgeons do not really know the characteristics of these biomedical devices they are placing in their patients. The objective of this work is to describe the chemical and morphological characteristics of 14 implant surfaces available on the market and to establish a simple and clear identification (ID) card for all of them, following the classification procedure developed in the Dohan Ehrenfest et al (2010) Codification (DEC) system. Fourteen implant surfaces were characterized: TiUnite (Nobel Biocare), Ospol (Ospol), Kohno HRPS (Sweden & Martina), Osseospeed (AstraTech), Ankylos (Dentsply Friadent), MTX (Zimmer), Promote (Camlog), BTI Interna (Biotechnology Institute), EVL Plus (SERF), Twinkon Ref (Tekka), Ossean (Intra-Lock), NanoTite (Biomet 3I), SLActive (ITI Straumann), Integra-CP/NanoTite (Bicon). Three samples of each implant were analyzed. Superficial chemical composition was analyzed using X-ray photoelectron spectroscopy/electron spectroscopy for chemical analysis, and the 100 nm in-depth profile was established using Auger electron spectroscopy. The microtopography was quantified using light interferometry. The general morphology and nanotopography were evaluated using a field emission-scanning electron microscope. Finally, the characterization code of each surface was established using the DEC system, and the main characteristics of each surface were summarized in a reader-friendly ID card. From a chemical standpoint, of the 14 different surfaces, 10 were based on a commercially pure titanium (grade 2 or 4), 3 on a titanium-aluminum alloy (grade 5 titanium), and one on a calcium phosphate core. Nine surfaces presented different forms of chemical impregnation or discontinuous coating of the titanium core, and 3 surfaces were covered with residual aluminablasting particles. Twelve surfaces presented different degrees of inorganic pollutions, and 2 presented a severe organic pollution

  20. Surface reformation and electro-optical characteristics of liquid crystal alignment layers using ion beam irradiation

    SciTech Connect

    Oh, Byeong-Yun; Lee, Kang-Min; Kim, Byoung-Yong; Kim, Young-Hwan; Han, Jin-Woo; Han, Jeong-Min; Lee, Sang-Keuk; Seo, Dae-Shik

    2008-09-15

    The surface modification characteristics of liquid crystal (LC) alignment layers irradiated with various argon (Ar) ion beam (IB) energies were investigated as a substitute for rubbing technology. Various pretilt angles were created on the IB-irradiated polyimide (PI) surfaces after IB irradiation, but the Ar ions did not alter the morphology on the PI surface, indicating that the pretilt angle was not due to microgrooves. The chemical bonding states of the IB-irradiated PI surfaces were analyzed in detail by x-ray photoelectron spectroscopy to verify the compositional behavior for the LC alignment. Chemical structure analysis showed that the alignment ability of LCs was due to the preferential reorientation of the carbon network due to the breaking of C=O double bonds in the imide ring parallel to the incident IB direction. The potential of applying nonrubbing technology to display devices was further supported by the superior electro-optical characteristics compared to rubbed PI.

  1. Use of AMSR-E microwave satellite data for land surface characteristics and snow cover variation.

    PubMed

    Boori, Mukesh Singh; Ferraro, Ralph R; Choudhary, Komal; Kupriyanov, Alexander

    2016-12-01

    This data article contains data related to the research article entitled "Global land cover classification based on microwave polarization and gradient ratio (MPGR)" [1] and "Microwave polarization and gradient ratio (MPGR) for global land surface phenology" [2]. This data article presents land surface characteristics and snow cover variation information from sensors like EOS Advanced Microwave Scanning Radiometer (AMSR-E). This data article use the HDF Explorer, Matlab, and ArcGIS software to process the pixel latitude, longitude, snow water equivalent (SWE), digital elevation model (DEM) and Brightness Temperature (BT) information from AMSR-E satellite data to provide land surface characteristics and snow cover variation data in all-weather condition at any time. This data information is useful to discriminate different land surface cover types and snow cover variation, which is turn, will help to improve monitoring of weather, climate and natural disasters.

  2. Quantitative analysis of surface characteristics and morphology in Death Valley, California using AIRSAR data

    NASA Technical Reports Server (NTRS)

    Kierein-Young, K. S.; Kruse, F. A.; Lefkoff, A. B.

    1992-01-01

    The Jet Propulsion Laboratory Airborne Synthetic Aperture Radar (JPL-AIRSAR) is used to collect full polarimetric measurements at P-, L-, and C-bands. These data are analyzed using the radar analysis and visualization environment (RAVEN). The AIRSAR data are calibrated using in-scene corner reflectors to allow for quantitative analysis of the radar backscatter. RAVEN is used to extract surface characteristics. Inversion models are used to calculate quantitative surface roughness values and fractal dimensions. These values are used to generate synthetic surface plots that represent the small-scale surface structure of areas in Death Valley. These procedures are applied to a playa, smooth salt-pan, and alluvial fan surfaces in Death Valley. Field measurements of surface roughness are used to verify the accuracy.

  3. Biomechanical and histomorphometric study of dental implants with different surface characteristics.

    PubMed

    Yeo, In-Sung; Han, Jung-Suk; Yang, Jae-Ho

    2008-11-01

    The aim of this study was to investigate the early bone response to the titanium dental implants with different surface characteristics using the rabbit tibia model. Calcium metaphosphate coated, anodic oxidized, hydroxyapatite particle-blasted, and turned (control) surfaces were compared. Surface topography was evaluated by field emission scanning electron microscope and optical interferometer. Eighteen rabbits received 72 implants in the tibia. Resonance frequency was analyzed every week for 6 weeks. Removal torque values were measured 2 and 6 weeks after placement. The implant-bone interfaces were directly observed by light microscope and bone-to-implant contact ratios were measured 2 and 6 weeks after insertion. All the surface-modified implants showed superior initial bone responses to the control. No significant differences were found among the surface-modified groups. Data suggest that various surface modification methods can provide favorable bone responses for early functioning and healing of dental implants.

  4. A Cellular Biophysics Textbook

    NASA Astrophysics Data System (ADS)

    Wilder, Alan Joseph

    2011-12-01

    In the past two decades, great advances have been made in understanding of the biophysical mechanisms of the protein machines that carry out the fundamental processes of the cell. It is now known that all major eukaryotic cellular processes require a complicated assemblage of proteins acting via a series of concerted motions. In order to grasp current understanding of cellular mechanisms, the new generation of cell biologists needs to be trained in the general characteristics of these cellular properties and the methods with which to study them. This cellular biophysics textbook, to be used in conjunction with the cellular biophysics course (MCB143) at UC-Davis, provides a great tool in the instruction of the new generation of cellular biologists. It provides a hierarchical view of the cell, from atoms to protein machines and explains in depth the mechanisms of cytoskeletal force generators as an example of these principles.

  5. Investigation on the adsorption characteristics of anserine on the surface of colloidal silver nanoparticles.

    PubMed

    Thomas, S; Maiti, N; Mukherjee, T; Kapoor, S

    2013-08-01

    The surface-enhanced Raman scattering (SERS) studies of anserine (beta-alanyl-N-methylhistidine) was carried out on colloidal silver nanoparticles to understand its adsorption characteristics. The experimentally observed Raman bands were assigned based on the results of DFT calculations. The studies suggest that the interaction of anserine is primarily through the carboxylate group with the imidazole ring in an upright position with respect to the silver surface. Concentration dependent SERS studies suggest a change in orientation at sub-monolayer concentration.

  6. Cell surface characteristics enable encrustation-free survival of neutrophilic iron-oxidizing bacteria

    NASA Astrophysics Data System (ADS)

    Saini, G.; Chan, C. S.

    2011-12-01

    Microbial growth in mineralizing environments depends on the cells' ability to evade surface precipitation. Cell-mineral interactions may be required for metabolism, but if unmoderated, cells could become encrusted, which would limit diffusion of nutrients and waste across cell walls. A combination of cell surface charge and hydrophobicity could enable the survival of microbes in such environments by inhibiting mineral attachment. To investigate this mechanism, we characterized the surfaces of two neutrophilic iron-oxidizing bacteria (FeOB): Mariprofundus ferrooxydans, a Zetaproteobacterium from Fe(II)-rich submarine hydrothermal vents and a Betaproteobacterium Gallionellales strain R-1, recently isolated from a ferrous groundwater seep. Both bacteria produce iron oxyhydroxides, yet successfully escape surface encrustation while inhabiting milieu where iron minerals are also produced by abiotic processes. SEM-EDX and TEM-EELS analyses of cultured bacteria revealed no iron on the cell surfaces. Zeta potential measurements showed that these bacteria have very small negative surface charge (0 to -4 mV) over a pH range of 4-9, indicating near-neutrally charged surfaces. Water contact angle measurements and thermodynamic calculations demonstrate that both bacteria and abiotically-formed Fe oxhydroxides are hydrophilic. Extended-DLVO calculations showed that hydrophilic repulsion between cells and minerals dominates over electrostatic and Lifshitz-van der Waals interactions. This leads to overall repulsion between microbes and minerals, thus preventing surface encrustation. Low surface charge and hydrophilicity (determined by microbial adhesion to hydrocarbon assay) were common features for both live and azide-inhibited cells, which shows that surface characteristics do not depend on active metabolism. It is remarkable that these two phylogenetically-distant bacteria from different environments employ similar adaptations to prevent surface mineralization. Our results

  7. Surface characteristics of nanocrystalline apatites: effect of mg surface enrichment on morphology, surface hydration species, and cationic environments.

    PubMed

    Bertinetti, Luca; Drouet, Christophe; Combes, Christele; Rey, Christian; Tampieri, Anna; Coluccia, Salvatore; Martra, Gianmario

    2009-05-19

    The incorporation of foreign ions, such as Mg2+, exhibiting a biological activity for bone regeneration is presently considered as a promising route for increasing the bioactivity of bone-engineering scaffolds. In this work, the morphology, structure, and surface hydration of biomimetic nanocrystalline apatites were investigated before and after surface exchange with such Mg2+ ions, by combining chemical alterations (ion exchange, H2O-D2O exchanges) and physical examinations (Fourier transform infrared spectroscopy (FTIR) and high-resolution transmission electron microscopy (HRTEM)). HRTEM data suggested that the Mg2+/Ca2+ exchange process did not affect the morphology and surface topology of the apatite nanocrystals significantly, while a new phase, likely a hydrated calcium and/or magnesium phosphate, was formed in small amount for high Mg concentrations. Near-infrared (NIR) and medium-infrared (MIR) spectroscopies indicated that the samples enriched with Mg2+ were found to retain more water at their surface than the Mg-free sample, both at the level of H2O coordinated to cations and adsorbed in the form of multilayers. Additionally, the H-bonding network in defective subsurface layers was also noticeably modified, indicating that the Mg2+/Ca2+ exchange involved was not limited to the surface. This work is intended to widen the present knowledge on Mg-enriched calcium phosphate-based bioactive materials intended for bone repair applications.

  8. Experimental Study on Surface Characteristics of Laser Cladding Layer Regulated by High-Frequency Microforging

    NASA Astrophysics Data System (ADS)

    Fan, Xiang Fang; Zhou, Ju; Qiu, Chang Jun; He, Bin; Ye, Jiang; Yuan, Bo; Pi, Zhengqing

    2011-03-01

    High-frequency microforging technology is used to produce micrometer-scale plastic deformation on the surface of material out of the vibration impact of a forging punch, and the cumulative effect of its various frequencies on micrometer-scale plastic deformation can cause changes of surface microstructure and mechanical properties. This study used (1) a self-made machine to treat NiCrBSi alloy, (2) a mechanical comparator and optical microscopy (OM) to study the geometric characteristics of plastic deformation, (3) OM and scanning electric microscopy (SEM) to observe influence on surface microstructure and cracking behavior of the laser cladding layer under microforging, (4) x-ray diffractometer (XRD) to measure the surface residual stress of laser cladding layer before and after forging, and (5) microhardness tester and wearing experimental machine to study changes of microhardness, friction coefficient, and wear characteristics of laser cladding layer after microforging. The results have shown that high-frequency microforging could produce plastic deformation about 150 μm deep on the surface of NiCrBSi alloy clad by laser. Regular dendrite and eutectic crystallization microstructure, which is a peculiar characteristic of the laser cladding layer, was broken into pieces and formed residual compression residual stress on the surface. Resistance to cracking of laser cladding layer improved greatly, microhardness and wearability increased, and the friction coefficient did not under go a noticeable change.

  9. Textured carbon on copper: A novel surface with extremely low secondary electron emission characteristics

    NASA Technical Reports Server (NTRS)

    Curren, A. N.; Jensen, K. A.

    1985-01-01

    Experimentally determined values of true secondary electron emission and relative values of reflected primary electron yield for a range of primary electron beam energies and beam impingement angles are presented for a series of novel textured carbon surfaces on copper substrates. (All copper surfaces used in this study were oxygen-free, high-conductivity grade). The purpose of this investigation is to provide information necessary to develop high-efficiency multistage depressed collectors (MDC's) for microwave amplifier traveling-wave tubes (TWT's) for communications and aircraft applications. To attain the highest TWT signal quality and overall efficiency, the MDC electrode surface must have low secondary electron emission characteristics. While copper is the material most commonly used for MDC electrodes, it exhibits relatively high levels of secondary electron emission unless its surface is treated for emission control. The textured carbon surface on copper substrate described in this report is a particularly promising candidate for the MDC electrode application. Samples of textured carbon surfaces on copper substrates typical of three different levels of treatment are prepared and tested for this study. The materials are tested at primary electron beam energies of 200 to 2000 eV and at direct (0 deg) to near-grazing (85 deg) beam impingement angles. True secondary electron emission and relative reflected primary electron yield characteristics of the textured surfaces are compared with each other and with those of untreated copper. All the textured carbon surfaces on copper substrate tested exhibited sharply lower secondary electron emission characteristics than those of an untreated copper surface.

  10. Electron reflection and secondary emission characteristics of sputter-textured pyrolytic graphite surfaces

    NASA Technical Reports Server (NTRS)

    Wintucky, E. G.; Curren, A. N.; Sovey, J. S.

    1981-01-01

    Low secondary and reflected primary electron emission from the collector electrode surfaces is important for optimum collector efficiency and hence for high overall efficiency of microwave amplifier tubes used in communication satellites and in military systems. Ion sputter texturing of the surface effectively suppresses electron emission from pyrolytic graphite, which is a promising collector electrode material. Secondary and reflected primary electron emission characteristics of sputter textured pyrolytic graphite surfaces with microstructures of various sizes and densities are presented. The microstructure with the lowest electron emission levels, less than those of soot, consists of a dense array of tall, thin spires.

  11. Development of Fractal Dimension and Characteristic Roughness Models for Turned Surface of Carbon Steels

    NASA Astrophysics Data System (ADS)

    Zuo, Xue; Zhu, Hua; Zhou, Yuankai; Ding, Cong; Sun, Guodong

    2016-08-01

    Relationships between material hardness, turning parameters (spindle speed and feed rate) and surface parameters (surface roughness Ra, fractal dimension D and characteristic roughness τ∗) are studied and modeled using response surface methodology (RSM). The experiments are carried out on a CNC lathe for six carbon steel material AISI 1010, AISI 1020, AISI 1030, AISI 1045, AISI 1050 and AISI 1060. The profile of turned surface and the surface roughness value are measured by a JB-5C profilometer. Based on the profile data, D and τ∗ are computed through the root-mean-square method. The analysis of variance (ANOVA) reveals that spindle speed is the most significant factors affecting Ra, while material hardness is the most dominant parameter affecting τ∗. Material hardness and spindle speed have the same influence on D. Feed rate has less effect on three surface parameters than spindle speed and material hardness. The second-order models of RSM are established for estimating Ra, D and τ∗. The validity of the developed models is approximately 80%. The response surfaces show that a surface with small Ra and large D and τ∗ can be obtained by selecting a high speed and a large hardness material. According to the established models, Ra, D and τ∗ of six carbon steels surfaces can be predicted under cutting conditions studied in this paper. The results have an instructive meaning to estimate the surface quality before turning.

  12. Spatio-temporal variations in surface characteristics over the North American Monsoon region

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this paper we summarize the surface characteristics for six locations in western Mexico and southwestern USA (from a subhumid climate in Jalisco, Mexico to the Sonoran Desert climate in Arizona, USA),that lie along a meridional transect within the North American Monsoon (NAM) core region using av...

  13. Dynamics of the physicotechnical characteristics of a metal during impact strengthening of its surface

    NASA Astrophysics Data System (ADS)

    Gradov, O. M.

    2015-12-01

    Based on the laws of conservation of energy and momentum, equations of the evolution of metal characteristics during impact strengthening of its surface have been deduced. The conditions of the optimal mode of treatment are determined and its effective time is estimated. The experimental data agree fairly well with the results of the equation solutions.

  14. Characteristics of ocean-reflected short radar pulses with application to altimetry and surface roughness determination

    NASA Technical Reports Server (NTRS)

    Miller, L. S.; Hayne, G. S.

    1972-01-01

    Current work related to geodetic altimetry is summarized. Special emphasis is placed on the effects of pulse length on both altimetry and sea-state estimation. Some discussion is also given of system tradeoff parameters and sea truth requirements to support scattering studies. The problem of analyzing signal characteristics and altimeter waveforms arising from rough surface backscattering is also considered.

  15. Influence of activated carbon characteristics on toluene and hexane adsorption: Application of surface response methodology

    NASA Astrophysics Data System (ADS)

    Izquierdo, Mª Teresa; de Yuso, Alicia Martínez; Valenciano, Raquel; Rubio, Begoña; Pino, Mª Rosa

    2013-01-01

    The objective of this study was to evaluate the adsorption capacity of toluene and hexane over activated carbons prepared according an experimental design, considering as variables the activation temperature, the impregnation ratio and the activation time. The response surface methodology was applied to optimize the adsorption capacity of the carbons regarding the preparation conditions that determine the physicochemical characteristics of the activated carbons. The methodology of preparation produced activated carbons with surface areas and micropore volumes as high as 1128 m2/g and 0.52 cm3/g, respectively. Moreover, the activated carbons exhibit mesoporosity, ranging from 64.6% to 89.1% the percentage of microporosity. The surface chemistry was characterized by TPD, FTIR and acid-base titration obtaining different values of surface groups from the different techniques because the limitation of each technique, but obtaining similar trends for the activated carbons studied. The exhaustive characterization of the activated carbons allows to state that the measured surface area does not explain the adsorption capacity for either toluene or n-hexane. On the other hand, the surface chemistry does not explain the adsorption results either. A compromise between physical and chemical characteristics can be obtained from the appropriate activation conditions, and the response surface methodology gives the optimal activated carbon to maximize adsorption capacity. Low activation temperature, intermediate impregnation ratio lead to high toluene and n-hexane adsorption capacities depending on the activation time, which a determining factor to maximize toluene adsorption.

  16. Effect of Autoclave Cycles on Surface Characteristics of S-File Evaluated by Scanning Electron Microscopy

    PubMed Central

    Razavian, Hamid; Iranmanesh, Pedram; Mojtahedi, Hamid; Nazeri, Rahman

    2016-01-01

    Introduction: Presence of surface defects in endodontic instruments can lead to unwanted complications such as instrument fracture and incomplete preparation of the canal. The current study was conducted to evaluate the effect of autoclave cycles on surface characteristics of S-File by scanning electron microscopy (SEM). Methods and Materials: In this experimental study, 17 brand new S-Files (#30) were used. The surface characteristics of the files were examined in four steps (without autoclave, 1 autoclave cycle, 5 autoclave cycles and 10 autoclave cycles) by SEM under 200× and 1000× magnifications. Data were analyzed using the SPSS software and the paired sample t-test, independent sample t-test and multifactorial repeated measures ANOVA. The level of significance was set at 0.05. Results: New files had debris and pitting on their surfaces. When the autoclave cycles were increased, the mean of surface roughness also increased at both magnifications (P<0.05). Moreover, under 1000× magnification the multifactorial repeated measures ANOVA showed more surface roughness (P<0.001). Conclusion: Sterilization by autoclave increased the surface roughness of the files and this had was directly related to the number of autoclave cycles. PMID:26843874

  17. Relationships between substrate, surface characteristics, and vegetation in an initial ecosystem

    NASA Astrophysics Data System (ADS)

    Biber, P.; Seifert, S.; Zaplata, M. K.; Schaaf, W.; Pretzsch, H.; Fischer, A.

    2013-12-01

    We investigated surface and vegetation dynamics in the artificial initial ecosystem "Chicken Creek" (Lusatia, Germany) in the years 2006-2011 across a wide spectrum of empirical data. We scrutinized three overarching hypotheses concerning (1) the relations between initial geomorphological and substrate characteristics with surface structure and terrain properties, (2) the effects of the latter on the occurrence of grouped plant species, and (3) vegetation density effects on terrain surface change. Our data comprise and conflate annual vegetation monitoring results, biennial terrestrial laser scans (starting in 2008), annual groundwater levels, and initially measured soil characteristics. The empirical evidence mostly confirms the hypotheses, revealing statistically significant relations for several goal variables: (1) the surface structure properties, local rill density, local relief energy and terrain surface height change; (2) the cover of different plant groups (annual, herbaceous, grass-like, woody, Fabaceae), and local vegetation height; and (3) terrain surface height change showed significant time-dependent relations with a variable that proxies local plant biomass. Additionally, period specific effects (like a calendar-year optimum effect for the occurrence of Fabaceae) were proven. Further and beyond the hypotheses, our findings on the spatiotemporal dynamics during the system's early development grasp processes which generally mark the transition from a geo-hydro-system towards a bio-geo-hydro system (weakening geomorphology effects on substrate surface dynamics, while vegetation effects intensify with time), where pure geomorphology or substrate feedbacks are changing into vegetation-substrate feedback processes.

  18. Effects of nitrogen plasma treatment on the surface characteristics of olive stone-based activated carbon.

    PubMed

    Soudani, Nouha; Najar-Souissi, Souad; Abderkader-Fernandez, Victor K; Ouederni, Abdelmottalab

    2017-04-01

    Nitrogen plasma treatment (NPT) of activated carbon (AC) at different conditions was carried out to introduce nitrogen-containing groups onto olive stone-activated carbon (OSAC) surfaces. Textural characteristics of raw and irradiated samples were analyzed by N2 and CO2 adsorption. Surface chemical functional groups were analyzed by X-ray photoelectron spectrometry (XPS) and Fourier Transformed Infrared spectroscopy. The results showed that after NPT, the surface textural properties of irradiated OSAC were slightly damaged, and a gradual decrease in surface area and pore volume was observed during the irradiation. XPS revealed that NPT could change the distribution of oxygen functional groups on the OSAC surface and there were more nitrogen atoms incorporated into the aromatic ring. A tentative explanation for the modification process is proposed. Phenol adsorption was enhanced from 110 mg/g for untreated AC to 635 mg/g for 30-min plasma-treated OSAC.

  19. Surface properties and adsorption characteristics to methylene blue and iodine of adsorbents from sludge.

    PubMed

    Deng, L Y; Xu, G R; Li, G B

    2010-01-01

    Adsorbent materials created from wastewater sludge have unique surface characteristics and could be effective in adsorption applications. In this research, the sludge-adsorbents were generated by pyrolyzing mixtures of sewage sludge and H(2)SO(4). Scanning electron microscope (SEM), thermal analysis, X-ray diffraction (XRD) and X-ray photoelectron spectroscope (XPS) were used to analyze the properties of sludge-adsorbent. XPS results show that the adsorbent surface functional groups with high contents of oxygen-containing groups serve as active sites for the adsorption and affect the surface characteristics; the adsorption mechanism of methylene blue (MB) is mainly Brönsted acid-base reaction between the adsorbent surface and MB; and iodine atoms are bonded to the surface of the adsorbent mainly by dispersive interactions rather than by electrostatic interactions. The results also show that H(2)SO(4) level, pyrolysis temperature and sulfuric acid/sludge weight ratio actually affected the adsorption characteristics. Using the conditions (H(2)SO(4) level of 1-18 M, pyrolysis temperature of 650°C, and weight ratio of 0.8), the adsorption capacities for MB and iodine were 74.7-62.3 mg g(-1) and 169.5-209.3 mg g(-1), respectively.

  20. Effect of the Surface Condition of a Wing on the Aerodynamic Characteristics of an Airplane

    NASA Technical Reports Server (NTRS)

    Defrance, S J

    1934-01-01

    In order to determine the effect of the surface conditions of a wing on the aerodynamic characteristics of an airplane, tests were conducted in the N.A.C.A. full-scale wind tunnel on the Fairchild F-22 airplane first with normal commercial finish of wing surface and later with the same wing polished. Comparison of the characteristics of the airplane with the two surface conditions shows that the polish caused a negligible change in the lift curve, but reduced the minimum drag coefficient by 0.001. This reduction in drag if applied to an airplane with a given speed of 200 miles per hour and a minimum drag coefficient of 0.025 would increase the speed only 2.9 miles per hour, but if the speed remained the same, the power would be reduced 4 percent.

  1. An Assessment of Land Surface and Lightning Characteristics Associated with Lightning-Initiated Wildfires

    NASA Technical Reports Server (NTRS)

    Coy, James; Schultz, Christopher J.; Case, Jonathan L.

    2017-01-01

    Can we use modeled information of the land surface and characteristics of lightning beyond flash occurrence to increase the identification and prediction of wildfires? Combine observed cloud-to-ground (CG) flashes with real-time land surface model output, and Compare data with areas where lightning did not start a wildfire to determine what land surface conditions and lightning characteristics were responsible for causing wildfires. Statistical differences between suspected fire-starters and non-fire-starters were peak-current dependent 0-10 cm Volumetric and Relative Soil Moisture comparisons were statistically dependent to at least the p = 0.05 independence level for both polarity flash types Suspected fire-starters typically occurred in areas of lower soil moisture than non-fire-starters. GVF value comparisons were only found to be statistically dependent for -CG flashes. However, random sampling of the -CG non-fire starter dataset revealed that this relationship may not always hold.

  2. System and method for non-destructive evaluation of surface characteristics of a magnetic material

    DOEpatents

    Jiles, David C.; Sipahi, Levent B.

    1994-05-17

    A system and a related method for non-destructive evaluation of the surface characteristics of a magnetic material. The sample is excited by an alternating magnetic field. The field frequency, amplitude and offset are controlled according to a predetermined protocol. The Barkhausen response of the sample is detected for the various fields and offsets and is analyzed. The system produces information relating to the frequency content, the amplitude content, the average or RMS energy content, as well as count rate information, for each of the Barkhausen responses at each of the excitation levels applied during the protocol. That information provides a contiguous body of data, heretofore unavailable, which can be analyzed to deduce information about the surface characteristics of the material at various depths below the surface.

  3. Evaluation of the depth of surface deterioration for concrete structure using dispersion characteristics of surface wave

    NASA Astrophysics Data System (ADS)

    Hsu, Keng-Tsang; Cheng, Chia-Chi; Tao, Hung-Yu; Chiang, Chih-Hung

    2017-02-01

    Surface waves generated by an impact are used to assess depth of deterioration for concrete plate. The proposed method uses one receiver positioned away from the impacting source. The spectrogram of the group velocity obtained from the signal recorded from the receiver is calculated by Short-Time Fourier Transform and the reassignment technique. Experiments were conduct on the concrete plate with top mortar layer to simulate concrete with serious aggregate segregation and bleeding. In the experiment, the responses corresponding to different source-receiver distance were explored. The results were shown by both slowness spectrogram and velocity profile. In the slowness spectrogram, substantial increase of velocity at low frequency domain is found. The velocity profile shows the change of wave speed is at the wave length about 1.2 times the mortar thickness. The results also show the lower velocity corresponding to the weak layer may be identified for source-receiver distance as short as 0.5 m but the wave speed may be underestimated.

  4. Biochemical characteristics and bacterial community structure of the sea surface microlayer in the South Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Obernosterer, I.; Catala, P.; Lami, R.; Caparros, J.; Ras, J.; Bricaud, A.; Dupuy, C.; van Wambeke, F.; Lebaron, P.

    2008-05-01

    The chemical and biological characteristics of the surface microlayer were determined during a transect across the South Pacific Ocean in October-December 2004. Concentrations of particulate organic carbon (1.3 to 7.6-fold) and nitrogen (1.4 to 7-fold), and POC:PON ratios were consistently higher in the surface microlayer as compared to surface waters (5 m). The large variability in particulate organic matter enrichment was negatively correlated to wind speed. No enhanced concentrations of dissolved organic carbon were detectable in the surface microlayer as compared to 5 m, but chromophoric dissolved organic matter was markedly enriched (by 2 to 4-fold) at all sites. Based on pigment analysis and cell counts, no consistent enrichment of any of the major components of the autotrophic and heterotrophic microbial community was detectable. CE-SSCP fingerprints and CARD FISH revealed that the bacterial communities present in the surface microlayer had close similarity (>76%) to those in surface waters. By contrast, bacterial heterotrophic production (3H-leucine incorporation) was consistently lower in the surface microlayer than in surface waters. By applying CARD-FISH and microautoradiography, we observed that Bacteroidetes and Gammaproteobacteria dominated leucine uptake in the surface microlayer, while in surface waters Bacteroidetes and Alphaproteobacteria were the major groups accounting for leucine incorporation. Our results demonstrate that the microbial community in the surface microlayer closely resembles that of the surface waters of the open ocean. Even a short residence in the surface microlayer influences leucine incorporation by different bacterial groups, probably as a response to the differences in the physical and chemical nature of the two layers.

  5. Surface structure characterization of Aspergillus fumigatus conidia mutated in the melanin synthesis pathway and their human cellular immune response.

    PubMed

    Bayry, Jagadeesh; Beaussart, Audrey; Dufrêne, Yves F; Sharma, Meenu; Bansal, Kushagra; Kniemeyer, Olaf; Aimanianda, Vishukumar; Brakhage, Axel A; Kaveri, Srini V; Kwon-Chung, Kyung J; Latgé, Jean-Paul; Beauvais, Anne

    2014-08-01

    In Aspergillus fumigatus, the conidial surface contains dihydroxynaphthalene (DHN)-melanin. Six-clustered gene products have been identified that mediate sequential catalysis of DHN-melanin biosynthesis. Melanin thus produced is known to be a virulence factor, protecting the fungus from the host defense mechanisms. In the present study, individual deletion of the genes involved in the initial three steps of melanin biosynthesis resulted in an altered conidial surface with masked surface rodlet layer, leaky cell wall allowing the deposition of proteins on the cell surface and exposing the otherwise-masked cell wall polysaccharides at the surface. Melanin as such was immunologically inert; however, deletion mutant conidia with modified surfaces could activate human dendritic cells and the subsequent cytokine production in contrast to the wild-type conidia. Cell surface defects were rectified in the conidia mutated in downstream melanin biosynthetic pathway, and maximum immune inertness was observed upon synthesis of vermelone onward. These observations suggest that although melanin as such is an immunologically inert material, it confers virulence by facilitating proper formation of the A. fumigatus conidial surface.

  6. Response surface methodology for predicting quality characteristics of beef patties added with flaxseed and tomato paste.

    PubMed

    Valenzuela Melendres, M; Camou, J P; Torrentera Olivera, N G; Alvarez Almora, E; González Mendoza, D; Avendaño Reyes, L; González Ríos, H

    2014-05-01

    Response surface methodology was used to study the effect of flaxseed flour (FS) and tomato paste (TP) addition, from 0 to 10% and 0 to 20% respectively, on beef patty quality characteristics. The assessed quality characteristics were color (L, a, and b), pH and texture profile analysis (TPA). Also, sensory analysis was performed for the assessment of color, juiciness, firmness, and general acceptance. FS addition reduced L and a values and decreased weight loss of cooked products (P<0.05). An opposite effect was observed when TP was added (P<0.05). All TPA parameters decreased when percentages of FS and TP were increased in the formulation of beef patties. Furthermore, FS and TP addition adversely affected the sensory characteristics of the cooked product (P<0.05); nevertheless, all sensory characteristics evaluated had an acceptable score (>5.6). Thus FS and TP are ingredients that can be used in beef patty preparation.

  7. Engineering a Biocompatible Scaffold with Either Micrometre or Nanometre Scale Surface Topography for Promoting Protein Adsorption and Cellular Response

    PubMed Central

    Le, Xuan; Poinern, Gérrard Eddy Jai; Ali, Nurshahidah; Berry, Cassandra M.; Fawcett, Derek

    2013-01-01

    Surface topographical features on biomaterials, both at the submicrometre and nanometre scales, are known to influence the physicochemical interactions between biological processes involving proteins and cells. The nanometre-structured surface features tend to resemble the extracellular matrix, the natural environment in which cells live, communicate, and work together. It is believed that by engineering a well-defined nanometre scale surface topography, it should be possible to induce appropriate surface signals that can be used to manipulate cell function in a similar manner to the extracellular matrix. Therefore, there is a need to investigate, understand, and ultimately have the ability to produce tailor-made nanometre scale surface topographies with suitable surface chemistry to promote favourable biological interactions similar to those of the extracellular matrix. Recent advances in nanoscience and nanotechnology have produced many new nanomaterials and numerous manufacturing techniques that have the potential to significantly improve several fields such as biological sensing, cell culture technology, surgical implants, and medical devices. For these fields to progress, there is a definite need to develop a detailed understanding of the interaction between biological systems and fabricated surface structures at both the micrometre and nanometre scales. PMID:23533416

  8. Effects of Er:YAG laser on bacteria associated with titanium surfaces and cellular response in vitro.

    PubMed

    Hauser-Gerspach, Irmgard; Mauth, Corinna; Waltimo, Tuomas; Meyer, Jürg; Stübinger, Stefan

    2014-07-01

    This in vitro study examined (a) the anti-bacterial efficacy of a pulsed erbium-doped yttrium aluminum garnet (Er:YAG) laser applied to Streptococcus sanguinis or Porphyromonas gingivalis adhered to either polished or microstructured titanium implant surfaces, (b) the response of osteoblast-like cells and (c) adhesion of oral bacteria to titanium surfaces after laser irradiation. Thereto, (a) bacteria adhered to titanium disks were irradiated with a pulsed Er:YAG laser (λ = 2,940 nm) at two different power settings: a lower mode (12.74 J/cm(2) calculated energy density) and a higher mode (63.69 J/cm(2)). (b) After laser irradiation with both settings of sterile titanium, disks were seeded with 10(4) MG-63 cells/cm(2). Adhesion and proliferation were determined after 1, 4, and 24 h by fluorescence microscopy and scanning electron microscopy. (c) Bacterial adhesion was also studied on irradiated (test) and non-irradiated (control) surfaces. Adhered P. gingivalis were effectively killed, even at the lower laser setting, independent of the material's surface. S. sanguinis cells adhered were effectively killed only at the higher setting of 63.69 J/cm(2). Laser irradiation of titanium surfaces had no significant effects on (b) adhesion or proliferation of osteoblast-like MG-63 cells or (c) adhesion of both oral bacterial species in comparison to untreated surfaces. An effective decontamination of polished and rough titanium implant surfaces with a Er:YAG laser could only be achieved with a fluence of 63.69 J/cm(2). Even though this setting may lead to certain surface alterations, no significant adverse effect on subsequent colonization and proliferation of MG-63 cells or increased bacterial adhesion was found in comparison to untreated control surfaces.

  9. Cellular tumorigenicity in nude mice. Test of associations among loss of cell-surface fibronectin, anchorage independence, and tumor-forming ability

    PubMed Central

    1979-01-01

    Fibronectin (FN; also called large external transformation-sensitive [LETS] protein or cell-surface protein [CSP]) is a large cell-surface glycoprotein that is frequently observed to be either absent or greatly reduced on the surfaces of malignant cells grown in vitro. Because FN may be a useful molecular marker of cellular malignancy, we have carried out an extensive screening to test the specific association among the degree of expression of FN, anchorage-independent growth, and tumorigenicity in the athymic nude mouse. A variety of diploid cell strains and established cell lines were tested for the expression of surface FN by indirect immunofluorescence using rabbit antisera against human cold insoluble globulin, rodent plasma FN, or chicken cell- surface FN. Concomitantly, the cells were assayed for tumor formation in nude mice and for the ability to form colonies in methylcellulose. Tumorigenic cells often showed very low surface fluorescence, confirming earlier reports. However, many highly tumorigenic fibroblast lines from several species stained strongly with all three antisera. In contrast, the anchorage-independent phenotype was nearly always associated with tumorigenicity in approximately 35 cell lines examined in this study. In another series of experiments, FN-positive but anchorage-independent cells were grown as tumors in nude mice and then reintroduced into culture. In five of the six tumor-derived cell lines, cell-surface FN was not significantly reduced; one such cell line showed very little surface FN. Our data thus indicate that the loss of cell-surface FN is not a necessary step in the process of malignant transformation and that the growth of FN-positive cells as tumors does not require a prior selection in vivo for FN-negative subpopulations. PMID:383723

  10. Surface accuracy and radiation pattern characteristics of mesh deployable refector antennas

    NASA Astrophysics Data System (ADS)

    Ueno, Miyoshi; Ebisui, Takashi; Okamato, Teruki; Orikasa, Teruaki; Sugimoto, Toshio; Iso, Akio

    To facilitate the growth of mobile satellite communications, both an increase in the Equivalent Isotropically Radiated Power (EIRP) of satellites and improved frequency reuse are required to achiveve compact size, low cost terminal usage, and high channel capacity. High gain and low sidelobe antenna technology are very important for high EIRP and frequency reuse, respectively. These requirements are expected to be met by using a large deployable mesh reflector antenna, which is the key technology for future multibeam moble communications systems. In this paper, surface accruracy and related electrical characteristics are studied using a TETRUS-(Tetra Trigonal Prism Truss) type deployable mesh reflector antenna. Surface accuracy and related electrical characteristics of reflector antennas becaue any distortion of the ideal paraboloidal configuration causes antenna patterns to deteriorate, thereby reducing reflector aperture efficiency and increasing sidelobe and grating lobe levels. The sidelobe and grating lobe characteristics are especially important in frequency reuse. First, we show the problem with the radiation pattern characteristics of TETUS antenna. We then propose a new antenna configuration called the 'HYBRID TETRUS' that improves these characteristics. The mechanical performances of two partial deployable models are also described. Mechanical testing results reveal agreement between the calculated and measured values and high rigidities.

  11. Ru(ii)-polypyridyl surface functionalised gold nanoparticles as DNA targeting supramolecular structures and luminescent cellular imaging agents

    NASA Astrophysics Data System (ADS)

    Martínez-Calvo, Miguel; Orange, Kim N.; Elmes, Robert B. P.; La Cour Poulsen, Bjørn; Williams, D. Clive; Gunnlaugsson, Thorfinnur

    2015-12-01

    The development of Ru(ii) functionalized gold nanoparticles 1-3.AuNP is described. These systems were found to be mono-disperse with a hydrodynamic radius of ca. 15 nm in water but gave rise to the formation of higher order structures in buffered solution. The interaction of 1-3.AuNP with DNA was also studied by spectroscopic and microscopic methods and suggested the formation of large self-assembly structures in solution. The uptake of 1-3.AuNP by cancer cells was studied using both confocal fluorescence as well as transmission electron microscopy (TEM), with the aim of investigating their potential as tools for cellular biology. These systems displaying a non-toxic profile with favourable photophysical properties may have application across various biological fields including diagnostics and therapeutics.The development of Ru(ii) functionalized gold nanoparticles 1-3.AuNP is described. These systems were found to be mono-disperse with a hydrodynamic radius of ca. 15 nm in water but gave rise to the formation of higher order structures in buffered solution. The interaction of 1-3.AuNP with DNA was also studied by spectroscopic and microscopic methods and suggested the formation of large self-assembly structures in solution. The uptake of 1-3.AuNP by cancer cells was studied using both confocal fluorescence as well as transmission electron microscopy (TEM), with the aim of investigating their potential as tools for cellular biology. These systems displaying a non-toxic profile with favourable photophysical properties may have application across various biological fields including diagnostics and therapeutics. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05598a

  12. Influence of the cooling liquid on surface quality characteristics in milling

    NASA Astrophysics Data System (ADS)

    Tampu, N. C.; Brabie, G.; Chirita, B. A.; Herghelegiu, E.; Radu, M. C.

    2015-11-01

    Cooling system and cooling liquid characteristics are among the main factors influencing surface quality and tool wear. The aim of this study is to analyse the effect of the cooling liquid, used in different concentrations and at different temperatures, on the quality of the surface layer processed by milling. In order to make this analysis a Minimum Quantity Lubrication (MQL) cooling device is used. Three different volumetric ratios were used to modify the concentration of the cooling fluid (25% water to 75% emulsion, 50% water to 50% emulsion, 75% water to 25% emulsion) and three different temperatures. The studies revealed that surface roughness can be correlated with the variation of the cooling liquid temperature while surface flatness can be correlated to both, cooling liquid temperature and concentration.

  13. A study of scattering characteristics for micro-scale rough surfaces

    NASA Astrophysics Data System (ADS)

    Won, Yonghee

    Defining the scatter characteristics of surfaces plays an important role in various technology industries such as the semiconductor, automobile, and military industries. Scattering can be used to inspect products for problems created during the manufacturing process and to generate the specifications for engineers. In particular, scattering measurement systems and models have been developed to define the surface properties of a wide variety of materials used in manufacturing. However, most previous research has been focused on very smooth surfaces as a nano-scale roughness. The research in this paper uses the Bidirectional Reflectance Distribution Function (BRDF) and focuses on defining the scattering properties of micro-scale rough and textured surfaces for three different incident angles. Also, the parameters of ABg and Harvey-Shack models are obtained for input into optical design software.

  14. Theoretical characteristics in supersonic flow of two types of control surfaces on triangular wings

    NASA Technical Reports Server (NTRS)

    Tucker, Warren A; Nelson, Robert L

    1949-01-01

    Methods based on the linearized theory for supersonic flow were used to find the characteristics of two types of control surfaces on thin triangular wings. The first type, the constant-chord partial-span flap, was considered to extend either outboard from the center of the wing or inboard from the wing tip. The second type, the full-triangular-tip flap, was treated only for the case in which the Mach number component normal to the leading edge is supersonic. For each type, expressions were found for the lift, rolling-moment, pitching-moment, and hinge-moment characteristics.

  15. Cell Surface Profiling Using High-Throughput Flow Cytometry: A Platform for Biomarker Discovery and Analysis of Cellular Heterogeneity

    PubMed Central

    Gedye, Craig A.; Hussain, Ali; Paterson, Joshua; Smrke, Alannah; Saini, Harleen; Sirskyj, Danylo; Pereira, Keira; Lobo, Nazleen; Stewart, Jocelyn; Go, Christopher; Ho, Jenny; Medrano, Mauricio; Hyatt, Elzbieta; Yuan, Julie; Lauriault, Stevan; Kondratyev, Maria; van den Beucken, Twan; Jewett, Michael; Dirks, Peter; Guidos, Cynthia J.; Danska, Jayne; Wang, Jean; Wouters, Bradly; Neel, Benjamin; Rottapel, Robert; Ailles, Laurie E.

    2014-01-01

    Cell surface proteins have a wide range of biological functions, and are often used as lineage-specific markers. Antibodies that recognize cell surface antigens are widely used as research tools, diagnostic markers, and even therapeutic agents. The ability to obtain broad cell surface protein profiles would thus be of great value in a wide range of fields. There are however currently few available methods for high-throughput analysis of large numbers of cell surface proteins. We describe here a high-throughput flow cytometry (HT-FC) platform for rapid analysis of 363 cell surface antigens. Here we demonstrate that HT-FC provides reproducible results, and use the platform to identify cell surface antigens that are influenced by common cell preparation methods. We show that multiple populations within complex samples such as primary tumors can be simultaneously analyzed by co-staining of cells with lineage-specific antibodies, allowing unprecedented depth of analysis of heterogeneous cell populations. Furthermore, standard informatics methods can be used to visualize, cluster and downsample HT-FC data to reveal novel signatures and biomarkers. We show that the cell surface profile provides sufficient molecular information to classify samples from different cancers and tissue types into biologically relevant clusters using unsupervised hierarchical clustering. Finally, we describe the identification of a candidate lineage marker and its subsequent validation. In summary, HT-FC combines the advantages of a high-throughput screen with a detection method that is sensitive, quantitative, highly reproducible, and allows in-depth analysis of heterogeneous samples. The use of commercially available antibodies means that high quality reagents are immediately available for follow-up studies. HT-FC has a wide range of applications, including biomarker discovery, molecular classification of cancers, or identification of novel lineage specific or stem cell markers. PMID:25170899

  16. Numerical simulation of cavitation flow characteristic on Pelton turbine bucket surface

    NASA Astrophysics Data System (ADS)

    Zeng, C. J.; Xiao, Y. X.; Zhu, W.; Yao, Y. Y.; Wang, Z. W.

    2015-01-01

    The internal flow in the rotating bucket of Pelton turbine is free water sheet flow with moving boundary. The runner operates under atmospheric and the cavitation in the bucket is still a controversial problem. While more and more field practice proved that there exists cavitation in the Pelton turbine bucket and the cavitation erosion may occur at the worst which will damage the bucket. So a well prediction about the cavitation flow on the bucket surface of Pelton turbine and the followed cavitation erosion characteristic can effectively guide the optimization of Pelton runner bucket and the stable operation of unit. This paper will investigate the appropriate numerical model and method for the unsteady 3D water-air-vapour multiphase cavitation flow which may occur on the Pelton bucket surface. The computational domain will include the nozzle pipe flow, semi-free surface jet and runner domain. Via comparing the numerical results of different turbulence, cavity and multiphase models, this paper will determine the suitable numerical model and method for the simulation of cavitation on the Pelton bucket surface. In order to investigate the conditions corresponding to the cavitation phenomena on the bucket surface, this paper will adopt the suitable model to simulate the various operational conditions of different water head and needle travel. Then, the characteristics of cavitation flow the development process of cavitation will be analysed in in great detail.

  17. Solid particle impingement erosion characteristics of cylindrical surfaces, pre-existing holes and slits

    NASA Technical Reports Server (NTRS)

    Rao, P. V.; Buckley, D. H.

    1983-01-01

    The erosion characteristics of aluminum cylinders sand-blasted with both spherical and angular erodent particles were studied and compared with results from previously studied flat surfaces. The cylindrical results are discussed with respect to impact conditions. The relationship between erosion rate and pit morphology (width, depth, and width to depth ratio) is established. The aspects of (1) erosion rate versus time curves on cylindrical surfaces; (2) long-term exposures; and (3) erosion rate versus time curves with spherical and angular particles are presented. The erosion morphology and characteristics of aluminum surfaces with pre-existing circular cylindrical and conical holes of different sizes were examined using weight loss measurements, scanning electron microscopy, a profilometer, and a depth gage. The morphological features (radial and concentric rings) are discussed with reference to flat surfaces, and the erosion features with spherical microglass beads. The similarities and differences of erosion and morphological features are highlighted. The erosion versus time curves of various shapes of holes are discussed and are compared with those of a flat surface. The erosion process at slits is considered.

  18. Investigation of dynamic characteristics of a rotor system with surface coatings

    NASA Astrophysics Data System (ADS)

    Yang, Yang; Cao, Dengqing; Wang, Deyou

    2017-02-01

    A Jeffcott rotor system with surface coatings capable of describing the mechanical vibration resulting from unbalance and rub-impact is formulated in this article. A contact force model proposed recently to describe the impact force between the disc and casing with coatings is employed to do the dynamic analysis for the rotor system with rubbing fault. Due to the variation of penetration, the contact force model is correspondingly modified. Meanwhile, the Coulomb friction model is applied to simulate the friction characteristics. Then, the case study of rub-impact with surface coatings is simulated by the Runge-Kutta method, in which a linear interpolation method is adopted to predict the rubbing instant. Moreover, the dynamic characteristics of the rotor system with surface coatings are analyzed in terms of bifurcation plot, waveform, whirl orbit, Poincaré map and spectrum plot. And the effects of the hardness of surface coatings on the response are investigated as well. Finally, compared with the classical models, the modified contact force model is shown to be more suitable to solve the rub-impact of aero-engine with surface coatings.

  19. Surface-anchored poly(acryloyl-L(D)-valine) with enhanced chirality-selective effect on cellular uptake of gold nanoparticles

    PubMed Central

    Deng, Jun; Wu, Sai; Yao, Mengyun; Gao, Changyou

    2016-01-01

    Chirality is one of the ubiquitous phenomena in biological systems. The left handed (L-) amino acids and right handed (D-) sugars are normally found in proteins, and in RNAs and DNAs, respectively. The effect of chiral surfaces at the nanoscale on cellular uptake has, however, not been explored. This study reveals for the first time the molecular chirality on gold nanoparticles (AuNPs) functions as a direct regulator for cellular uptake. Monolayers of 2-mercaptoacetyl-L(D)-valine (L(D)-MAV) and poly(acryloyl-L(D)-valine (L(D)-PAV) chiral molecules were formed on AuNPs surface, respectively. The internalized amount of PAV-AuNPs was several times larger than that of MAV-AuNPs by A549 and HepG2 cells, regardless of the chirality difference. However, the D-PAV-AuNPs were internalized with significantly larger amount than the L-PAV-AuNPs. This chirality-dependent uptake effect is likely attributed to the preferable interaction between the L-phospholipid-based cell membrane and the D-enantiomers. PMID:27531648

  20. Identification of microbes from the surfaces of food-processing lines based on the flow cytometric evaluation of cellular metabolic activity combined with cell sorting.

    PubMed

    Juzwa, W; Duber, A; Myszka, K; Białas, W; Czaczyk, K

    2016-09-01

    In this study the design of a flow cytometry-based procedure to facilitate the detection of adherent bacteria from food-processing surfaces was evaluated. The measurement of the cellular redox potential (CRP) of microbial cells was combined with cell sorting for the identification of microorganisms. The procedure enhanced live/dead cell discrimination owing to the measurement of the cell physiology. The microbial contamination of the surface of a stainless steel conveyor used to process button mushrooms was evaluated in three independent experiments. The flow cytometry procedure provided a step towards monitoring of contamination and enabled the assessment of microbial food safety hazards by the discrimination of active, mid-active and non-active bacterial sub-populations based on determination of their cellular vitality and subsequently single cell sorting to isolate microbial strains from discriminated sub-populations. There was a significant correlation (r = 0.97; p < 0.05) between the bacterial cell count estimated by the pour plate method and flow cytometry, despite there being differences in the absolute number of cells detected. The combined approach of flow cytometric CRP measurement and cell sorting allowed an in situ analysis of microbial cell vitality and the identification of species from defined sub-populations, although the identified microbes were limited to culturable cells.

  1. Surface-anchored poly(acryloyl-L(D)-valine) with enhanced chirality-selective effect on cellular uptake of gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Deng, Jun; Wu, Sai; Yao, Mengyun; Gao, Changyou

    2016-08-01

    Chirality is one of the ubiquitous phenomena in biological systems. The left handed (L-) amino acids and right handed (D-) sugars are normally found in proteins, and in RNAs and DNAs, respectively. The effect of chiral surfaces at the nanoscale on cellular uptake has, however, not been explored. This study reveals for the first time the molecular chirality on gold nanoparticles (AuNPs) functions as a direct regulator for cellular uptake. Monolayers of 2-mercaptoacetyl-L(D)-valine (L(D)-MAV) and poly(acryloyl-L(D)-valine (L(D)-PAV) chiral molecules were formed on AuNPs surface, respectively. The internalized amount of PAV-AuNPs was several times larger than that of MAV-AuNPs by A549 and HepG2 cells, regardless of the chirality difference. However, the D-PAV-AuNPs were internalized with significantly larger amount than the L-PAV-AuNPs. This chirality-dependent uptake effect is likely attributed to the preferable interaction between the L-phospholipid-based cell membrane and the D-enantiomers.

  2. Surface-anchored poly(acryloyl-L(D)-valine) with enhanced chirality-selective effect on cellular uptake of gold nanoparticles.

    PubMed

    Deng, Jun; Wu, Sai; Yao, Mengyun; Gao, Changyou

    2016-08-17

    Chirality is one of the ubiquitous phenomena in biological systems. The left handed (L-) amino acids and right handed (D-) sugars are normally found in proteins, and in RNAs and DNAs, respectively. The effect of chiral surfaces at the nanoscale on cellular uptake has, however, not been explored. This study reveals for the first time the molecular chirality on gold nanoparticles (AuNPs) functions as a direct regulator for cellular uptake. Monolayers of 2-mercaptoacetyl-L(D)-valine (L(D)-MAV) and poly(acryloyl-L(D)-valine (L(D)-PAV) chiral molecules were formed on AuNPs surface, respectively. The internalized amount of PAV-AuNPs was several times larger than that of MAV-AuNPs by A549 and HepG2 cells, regardless of the chirality difference. However, the D-PAV-AuNPs were internalized with significantly larger amount than the L-PAV-AuNPs. This chirality-dependent uptake effect is likely attributed to the preferable interaction between the L-phospholipid-based cell membrane and the D-enantiomers.

  3. The characteristic function method and exact solutions of nonlinear sheared flows with free surface under gravity

    NASA Astrophysics Data System (ADS)

    Abd-El-Malek, Mina B.; Helal, Medhat M.

    2006-05-01

    Method of characteristic function has been applied for solving a system of first order nonlinear sheared flows with a free surface. The application of a one-parameter group of infinitesimal transformations reduces the number of independent variables by one, and consequently, by applying this method twice, the system of partial differential equations, in three independent variables, with the boundary conditions reduces to a system of ordinary differential equations with the appropriate corresponding conditions. The obtained differential equations are solved analytically and the forms of the free surface, the horizontal component and vertical component of the velocity are obtained in closed form for different cases. The results are illustrated graphically for different parameters.

  4. The effects of liquid-phase oxidation of multiwall carbon nanotubes on their surface characteristics

    NASA Astrophysics Data System (ADS)

    Burmistrov, I. N.; Muratov, D. S.; Ilinykh, I. A.; Kolesnikov, E. A.; Godymchuk, A. Yu; Kuznetsov, D. V.

    2016-01-01

    The development of new sorbents based on nanostructured carbon materials recently became a perspective field of research. Main topic of current study is to investigate the effect of different regimes of multiwall carbon nanotubes (MWCNT) surface modification process on their structural characteristics. MWCNT samples were treated with nitric acid at high temperature. Structural properties were studied using low temperature nitrogen adsorption and acid-base back titration methods. The study showed that diluted nitric acid does not affect MWCNT structure. Concentrated nitric acid treatment leads to formation of 2.8 carboxylic groups per 1 nm2 of the sample surface.

  5. Surface characteristic changes of dental ceramics after cyclic immersion in acidic agents and titratable acidity.

    PubMed

    Junpoom, Peerapong; Kukiattrakoon, Boonlert; Hengtrakool, Chanothai

    2010-12-01

    The potential erosive effect of acidic food, sour fruits and drinks on all-ceramic restorations used in dentistry has not been clearly documented. Surface characteristic changes have been evaluated and compared for disc-shaped specimens (diameter 12.0 mm and thickness 2.0 mm) of fluorapatite-leucite and fluorapatite ceramics using various storage agents (deionized water, citrate buffer solution, pineapple juice, green mango juice, cola soft drink and 4% acetic acid). Immersion in pineapple juice, green mango juice, cola soft drink and 4% acetic acid for 16 hours produce significant increases in surface roughness for both types of ceramics investigated.

  6. Propagation and attenuation characteristics of azimuthal symmetric surface waves in un-magnetized plasma column

    NASA Astrophysics Data System (ADS)

    Li, Wenqiu; Wang, Gang; Xiang, Dong; Su, Xiaobao

    2016-11-01

    Phase and attenuation properties of azimuthal symmetric surface waves are investigated analytically in an un-magnetized cylindrical plasma column based on the transcendental dispersion relation. A novel method of calculating the wave power deposition in terms of complex electric conductivity is proposed. Electron density distribution is obtained theoretically through charged particle balance theory. It is shown that the effect of the electron temperature on the dispersion curve can be neglected when kzα < 1. Both the phase/attenuation characteristics and wave energy deposition properties of the azimuthal symmetric surface wave have an evident dependence on the electron density and the electron collision frequency.

  7. Relationship between wettability and lubrication characteristics of the surfaces of contacting phospholipid-based membranes.

    PubMed

    Pawlak, Zenon; Petelska, Aneta D; Urbaniak, Wieslaw; Yusuf, Kehinde Q; Oloyede, Adekunle

    2013-04-01

    The wettability of the articular surface of cartilage depends on the condition of its surface active phospholipid overlay, which is structured as multi-bilayer. Based on a hypothesis that the surface of cartilage facilitates the almost frictionless lubrication of the joint, we examined the characteristics of this membrane surface entity in both its normal and degenerated conditions using a combination of atomic force microscopy, contact angle measurement, and friction test methods. The observations have led to the conclusions that (1) the acid-base equilibrium condition influences the lubrication effectiveness of the surface of cartilage and (2) the friction coefficient is significantly dependent on the hydrophobicity of the surface of the tissue, thereby confirming the hypothesis tested in this paper. Both wettability angle and interfacial energy were obtained for varying conditions of the cartilage surface both in its wet, dry and lipid-depleted conditions. The interfacial energy also increased with mole fraction of the lipid species reaching an asymptotic value after 0.6. Also, the friction coefficient was found to decrease to an asymptotic level as the wettability angle increased. The result reveal that the interfacial energy increased with pH till pH = 4.0, and then decreased from pH = 4.0 to reach equilibrium at pH = 7.0.

  8. Nanoscale surface modifications to control capillary flow characteristics in PMMA microfluidic devices

    PubMed Central

    2011-01-01

    Polymethylmethacrylate (PMMA) microfluidic devices have been fabricated using a hot embossing technique to incorporate micro-pillar features on the bottom wall of the device which when combined with either a plasma treatment or the coating of a diamond-like carbon (DLC) film presents a range of surface modification profiles. Experimental results presented in detail the surface modifications in the form of distinct changes in the static water contact angle across a range from 44.3 to 81.2 when compared to pristine PMMA surfaces. Additionally, capillary flow of water (dyed to aid visualization) through the microfluidic devices was recorded and analyzed to provide comparison data between filling time of a microfluidic chamber and surface modification characteristics, including the effects of surface energy and surface roughness on the microfluidic flow. We have experimentally demonstrated that fluid flow and thus filling time for the microfluidic device was significantly faster for the device with surface modifications that resulted in a lower static contact angle, and also that the incorporation of micro-pillars into a fluidic device increases the filling time when compared to comparative devices. PMID:21711936

  9. Surface characteristics, corrosion and bioactivity of chemically treated biomedical grade NiTi alloy.

    PubMed

    Chembath, Manju; Balaraju, J N; Sujata, M

    2015-11-01

    The surface of NiTi alloy was chemically modified using acidified ferric chloride solution and the characteristics of the alloy surface were studied from the view point of application as a bioimplant. Chemically treated NiTi was also subjected to post treatments by annealing at 400°C and passivation in nitric acid. The surface of NiTi alloy after chemical treatment developed a nanogrid structure with a combination of one dimensional channel and two dimensional network-like patterns. From SEM studies, it was found that the undulations formed after chemical treatment remained unaffected after annealing, while after passivation process the undulated surface was filled with oxides of titanium. XPS analysis revealed that the surface of passivated sample was enriched with oxides of titanium, predominantly TiO2. The influence of post treatment on the corrosion resistance of chemically treated NiTi alloy was monitored using Potentiodynamic Polarization and Electrochemical Impedance Spectroscopy (EIS) in Phosphate Buffered Saline (PBS) solution. In the chemically treated condition, NiTi alloy exhibited poor corrosion resistance due to the instability of the surface. On the other hand, the breakdown potential (0.8V) obtained was highest for the passivated samples compared to other surface treated samples. During anodic polarization, chemically treated samples displayed dissolution phenomenon which was predominantly activation controlled. But after annealing and passivation processes, the behavior of anodic polarization was typical of a diffusion controlled process which confirmed the enhanced passivity of the post treated surfaces. The total resistance, including the porous and barrier layer, was in the range of mega ohms for passivated surfaces, which could be attributed to the decrease in surface nickel content and formation of compact titanium oxide. The passivated sample displayed good bioactivity in terms of hydroxyapatite growth, noticed after 14days immersion in

  10. The Porpoising Characteristics of a Planing Surface Representing the Forebody of a Flying-Boat Hull

    NASA Technical Reports Server (NTRS)

    Benson, James M.

    1942-01-01

    Porpoising characteristics were observed on V-body fitted with tail surfaces for different combinations of load, speed, moment of inertia, location of pivot, elevator setting, and tail area. A critical trim was found which was unaltered by elevator setting or tail area. Critical trim was lowered by moving pivot either forward or down or increasing radius or gyration. Increase in mass and moment of inertia increased amplitude of oscillations. Complete results are tabulated and shown graphically.

  11. Surface interactions with compartmentalized cellular phosphates explain rare earth oxide nanoparticle hazard and provide opportunities for safer design.

    PubMed

    Li, Ruibin; Ji, Zhaoxia; Chang, Chong Hyun; Dunphy, Darren R; Cai, Xiaoming; Meng, Huan; Zhang, Haiyuan; Sun, Bingbing; Wang, Xiang; Dong, Juyao; Lin, Sijie; Wang, Meiying; Liao, Yu-Pei; Brinker, C Jeffrey; Nel, Andre; Xia, Tian

    2014-02-25

    Growing international exploitation of rare earth oxides (REOs) for commercial and biological use has increased the possibility of human exposure and adverse health effects. Occupational exposure to rare earth materials in miners and polishers leads to a severe form of pneumoconiosis, while gadolinium-containing MRI contrast agents cause nephrogenic systemic fibrosis in patients with renal impairment. The mechanisms for inducing these adverse pro-fibrogenic effects are of considerable importance for the safety assessment of REO particles as well as presenting opportunities for safer design. In this study, using a well-prepared REO library, we obtained a mechanistic understanding of how REOs induce cellular and pulmonary damage by a compartmentalized intracellular biotransformation process in lysosomes that results in pro-fibrogenic growth factor production and lung fibrosis. We demonstrate that rare earth oxide ion shedding in acidifying macrophage lysosomes leads to biotic phosphate complexation that results in organelle damage due to stripping of phosphates from the surrounding lipid bilayer. This results in nanoparticle biotransformation into urchin shaped structures and setting in motion a series of events that trigger NLRP3 inflammasome activation, IL-1β release, TGF-β1 and PDGF-AA production. However, pretreatment of REO nanoparticles with phosphate in a neutral pH environment prevents biological transformation and pro-fibrogenic effects. This can be used as a safer design principle for producing rare earth nanoparticles for biological use.

  12. Augmented cellular uptake of nanoparticles using tea catechins: effect of surface modification on nanoparticle-cell interaction

    NASA Astrophysics Data System (ADS)

    Lu, Yi-Ching; Luo, Pei-Chun; Huang, Chun-Wan; Leu, Yann-Lii; Wang, Tzu-Hao; Wei, Kuo-Chen; Wang, Hsin-Ell; Ma, Yunn-Hwa

    2014-08-01

    Nanoparticles may serve as carriers in targeted therapeutics; interaction of the nanoparticles with a biological system may determine their targeting effects and therapeutic efficacy. Epigallocatechin-3-gallate (EGCG), a major component of tea catechins, has been conjugated with nanoparticles and tested as an anticancer agent. We investigated whether EGCG may enhance nanoparticle uptake by tumor cells. Cellular uptake of a dextran-coated magnetic nanoparticle (MNP) was determined by confocal microscopy, flow cytometry or a potassium thiocyanate colorimetric method. We demonstrated that EGCG greatly enhanced interaction and/or internalization of MNPs (with or without polyethylene glycol) by glioma cells, but not vascular endothelial cells. The enhancing effects are both time- and concentration-dependent. Such effects may be induced by a simple mix of MNPs with EGCG at a concentration as low as 1-3 μM, which increased MNP uptake 2- to 7-fold. In addition, application of magnetic force further potentiated MNP uptake, suggesting a synergetic effect of EGCG and magnetic force. Because the effects of EGCG were preserved at 4 °C, but not when EGCG was removed from the culture medium prior to addition of MNPs, a direct interaction of EGCG and MNPs was implicated. Use of an MNP-EGCG composite produced by adsorption of EGCG and magnetic separation also led to an enhanced uptake. The results reveal a novel interaction of a food component and nanocarrier system, which may be potentially amenable to magnetofection, cell labeling/tracing, and targeted therapeutics.

  13. Augmented cellular uptake of nanoparticles using tea catechins: effect of surface modification on nanoparticle-cell interaction.

    PubMed

    Lu, Yi-Ching; Luo, Pei-Chun; Huang, Chun-Wan; Leu, Yann-Lii; Wang, Tzu-Hao; Wei, Kuo-Chen; Wang, Hsin-Ell; Ma, Yunn-Hwa

    2014-09-07

    Nanoparticles may serve as carriers in targeted therapeutics; interaction of the nanoparticles with a biological system may determine their targeting effects and therapeutic efficacy. Epigallocatechin-3-gallate (EGCG), a major component of tea catechins, has been conjugated with nanoparticles and tested as an anticancer agent. We investigated whether EGCG may enhance nanoparticle uptake by tumor cells. Cellular uptake of a dextran-coated magnetic nanoparticle (MNP) was determined by confocal microscopy, flow cytometry or a potassium thiocyanate colorimetric method. We demonstrated that EGCG greatly enhanced interaction and/or internalization of MNPs (with or without polyethylene glycol) by glioma cells, but not vascular endothelial cells. The enhancing effects are both time- and concentration-dependent. Such effects may be induced by a simple mix of MNPs with EGCG at a concentration as low as 1-3 μM, which increased MNP uptake 2- to 7-fold. In addition, application of magnetic force further potentiated MNP uptake, suggesting a synergetic effect of EGCG and magnetic force. Because the effects of EGCG were preserved at 4 °C, but not when EGCG was removed from the culture medium prior to addition of MNPs, a direct interaction of EGCG and MNPs was implicated. Use of an MNP-EGCG composite produced by adsorption of EGCG and magnetic separation also led to an enhanced uptake. The results reveal a novel interaction of a food component and nanocarrier system, which may be potentially amenable to magnetofection, cell labeling/tracing, and targeted therapeutics.

  14. Cellular Reflectarray Antenna

    NASA Technical Reports Server (NTRS)

    Romanofsky, Robert R.

    2010-01-01

    The cellular reflectarray antenna is intended to replace conventional parabolic reflectors that must be physically aligned with a particular satellite in geostationary orbit. These arrays are designed for specified geographical locations, defined by latitude and longitude, each called a "cell." A particular cell occupies nominally 1,500 square miles (3,885 sq. km), but this varies according to latitude and longitude. The cellular reflectarray antenna designed for a particular cell is simply positioned to align with magnetic North, and the antenna surface is level (parallel to the ground). A given cellular reflectarray antenna will not operate in any other cell.

  15. Biochemical characteristics and bacterial community structure of the sea surface microlayer in the South Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Obernosterer, I.; Catala, P.; Lami, R.; Caparros, J.; Ras, J.; Bricaud, A.; Dupuy, C.; van Wambeke, F.; Lebaron, P.

    2007-08-01

    The chemical and biological characteristics of the surface microlayer were determined during a transect across the South Pacific Ocean in October-December 2004. Concentrations of particulate organic carbon (1.3 to 7.6-fold) and nitrogen (1.4 to 7), and POC:PON ratios were consistently higher in the surface microlayer as compared to subsurface waters (5 m). The large variability in particulate organic matter enrichment was negatively correlated to wind speed. No enhanced concentrations of dissolved organic carbon were detectable in the surface microlayer as compared to 5 m, but chromophoric dissolved organic matter was markedly enriched (by 2 to 4-fold) at all sites. Based on pigment analysis and cell counts, no consistent enrichment of any of the major components of the autotrophic and heterotrophic microbial community was detectable. CE-SSCP fingerprints and CARD FISH revealed that the bacterial communities present in the surface microlayer had close similarity (>76%) to those in subsurface waters. By contrast, bacterial heterotrophic production (3H-leucine incorporation) was consistently lower in the surface microlayer than in subsurface waters. By applying CARD-FISH and microautoradiography, we observed that Bacteroidetes and Gammaproteobacteria dominated leucine uptake in the surface microlayer, while in subsurface waters Bacteroidetes and Alphaproteobacteria were the major groups accounting for leucine incorporation. Our results demonstrate that the microbial community in the surface microlayer closely resembles that of the surface waters of the open ocean. However, even short time periods in the surface microlayer result in differences in bacterial groups accounting for leucine incorporation, probably as a response to the differences in the physical and chemical nature of the two layers.

  16. Investigations into the molecular-level adhesion characteristics of hydroxyapatite-coated and anodized titanium surfaces using the molecular orbital approach.

    PubMed

    Saju, K K; Jayadas, N H; Vidyanand, S; James, J

    2011-03-01

    It has been established that the adhesion of cells on to the surfaces of orthopaedic implants depends on the ability of the surfaces to accommodate protein molecules. Hydroxyapatite coating and anodizing are the most common methods to make TiAl6V4 implants (Ti) more biocompatible. In this paper Spartan 02, a molecular dynamics software, is used to analyze and predict the bonding characteristics of Extra cellular matrix protein sequence arginine-glycine-aspartic acid (RGD) on a Hyrdoxyapatite (HA) coated Ti and an anodized Ti surface based on the property of its constituent atoms, their polarity (net electrostatic charge, Qr), the energies of the molecular orbital E_HOMO (energy of the highest occupied molecular orbital), and E_LUMO (energy of the lowest unoccupied molecular orbital). The results show favourable criterion for formation of bonding between the HOMO orbital of the HA coated and anodized surfaces and LUMO orbital of the glycine strand from the RGD unit. The mechanism of bonding of individual atoms to form primary calcium oxide compounds is likely only in the case of HA coated surfaces . The surface texture of the anodized Ti with inherent porosities appear more responsible for the adsorption of proteins on to them by mechanical interlocking than the formation of any intermediate calcium oxide compounds.

  17. Characteristics of surface solar radiation in Sino-Singapore Eco-city

    NASA Astrophysics Data System (ADS)

    Hou, M.; Huang, H.; Shen, Y. F.; Yao, W.; Wang, G. S.; Bu, Q. J.; Shan, X. L.; Chang, C. H.

    2017-01-01

    Using solar observation and meteorological data of the Sino-Singapore Tianjin Eco-city from August 14th 2014 to August 12th 2015, characteristics of solar radiation of the eco-city and characteristics of solar radiation on a tilted surface under different weather conditions were analyzed and assessed. And the accuracy and error sources of isotropic and anisotropic calculation model for solar radiation on a tilted surface were studied. The results show that observed radiation on a horizontal and tilted surface is quite different at monthly, seasonal and annual time scales, so the estimated photovoltaic power generation based on the solar radiation on a horizontal surface is not accurate. Diurnal cycle of solar radiation is affected by different weather conditions and the power stations need to adjust generation strategies according to weather conditions. Accuracy of the two kinds of tilted radiation calculation models is similar and the overall calculation effect is reasonable. The uncertainty of the direct portion segment calculation function is the main cause of calculated errors.

  18. Spectra investigation on surface characteristics of graphene oxide nanosheets treated with tartaric, malic and oxalic acids

    NASA Astrophysics Data System (ADS)

    Teng, Xiyao; Yan, Manqing; Bi, Hong

    2014-01-01

    The surface characteristics of graphene oxide nanosheets (GO) treated respectively with tartaric acid, malic acid and oxalic acid, have been investigated by mainly using optical spectroscopic methods including Fourier transform infrared spectroscopy (FT-IR), Ultraviolet-visible (UV-Vis) absorption and Raman spectroscopy. Additionally, the electrochemical property of the products has also been studied. The data revealed that oxygen-containing groups such as sbnd OH, sbnd COOH and sbnd Cdbnd O on the GO surface have been almost removed and thus reduced graphene oxide nanosheets (RGN) were obtained. Interestingly, the number of sp2 domains of RGN increases as treated by tartaric acid < malic acid < oxalic acid whereas the steric hindrance (SH) decreases and the ionization constant (IC) differs among these three acids. Furthermore, the specific capacitances (Cs) of GO have been greatly promoted from 2.4 F g-1 to 100.8, 112.4, and 147 F g-1 after treated with tartaric, malic and oxalic acids, respectively. This finding agrees well with the spectra result of the tendency of surface conjugated degree alteration. We claim that the difference in both SH and IC among these acids is the main reason for the diverse surface characteristics as well as the improved Cs of the RGN.

  19. Spectra investigation on surface characteristics of graphene oxide nanosheets treated with tartaric, malic and oxalic acids.

    PubMed

    Teng, Xiyao; Yan, Manqing; Bi, Hong

    2014-01-24

    The surface characteristics of graphene oxide nanosheets (GO) treated respectively with tartaric acid, malic acid and oxalic acid, have been investigated by mainly using optical spectroscopic methods including Fourier transform infrared spectroscopy (FT-IR), Ultraviolet-visible (UV-Vis) absorption and Raman spectroscopy. Additionally, the electrochemical property of the products has also been studied. The data revealed that oxygen-containing groups such as OH, COOH and CO on the GO surface have been almost removed and thus reduced graphene oxide nanosheets (RGN) were obtained. Interestingly, the number of sp(2) domains of RGN increases as treated by tartaric acidsurface conjugated degree alteration. We claim that the difference in both SH and IC among these acids is the main reason for the diverse surface characteristics as well as the improved Cs of the RGN.

  20. Influence of Shot Peening on Surface Characteristics of High-Speed Steels

    NASA Astrophysics Data System (ADS)

    Harada, Yasunori; Fukaura, Kenzo

    High-speed steels are generally used for the cutting of other hard materials. These are hard materials, and can be used at high temperatures. Therefore, some of them are used for warm metal forming such as forging. However, in the tools used in hot working, an excellent hot hardness and long-life fatigue are strongly required. In the present study, the influence of shot peening on the surface characteristics of high-speed steels was investigated. Shot peening imparts compressive residual stresses on the metal surface, thus improving the fatigue life of the machine parts. In the experiment, the shot peening treatment was performed using an air-type shot peening machine. The shots made of cemented carbide were used. The workpieces were two types, W-type and Mo-type alloys. Surface roughness, compressive residual stress, and hardness of the peened workpieces were measured. It was found that shot peening using the hard shot media was effective in improving the surface characteristics of high-speed steels.

  1. Surface transfer doping induced effective modulation on ambipolar characteristics of few-layer black phosphorus.

    PubMed

    Xiang, Du; Han, Cheng; Wu, Jing; Zhong, Shu; Liu, Yiyang; Lin, Jiadan; Zhang, Xue-Ao; Ping Hu, Wen; Özyilmaz, Barbaros; Neto, A H Castro; Wee, Andrew Thye Shen; Chen, Wei

    2015-03-12

    Black phosphorus, a fast emerging two-dimensional material, has been configured as field effect transistors, showing a hole-transport-dominated ambipolar characteristic. Here we report an effective modulation on ambipolar characteristics of few-layer black phosphorus transistors through in situ surface functionalization with caesium carbonate (Cs2CO3) and molybdenum trioxide (MoO3), respectively. Cs2CO3 is found to strongly electron dope black phosphorus. The electron mobility of black phosphorus is significantly enhanced to ~27 cm(2) V(-1) s(-1) after 10 nm Cs2CO3 modification, indicating a greatly improved electron-transport behaviour. In contrast, MoO3 decoration demonstrates a giant hole-doping effect. In situ photoelectron spectroscopy characterization reveals significant surface charge transfer occurring at the dopants/black phosphorus interfaces. Moreover, the surface-doped black phosphorus devices exhibit a largely enhanced photodetection behaviour. Our findings coupled with the tunable nature of the surface transfer doping scheme ensure black phosphorus as a promising candidate for further complementary logic electronics.

  2. Influence of lipid coatings on surface wettability characteristics of silicone hydrogels.

    PubMed

    Bhamla, M Saad; Nash, Walter L; Elliott, Stacey; Fuller, Gerald G

    2015-04-07

    Insoluble lipids serve vital functions in our bodies and interact with biomedical devices, e.g., the tear film on a contact lens. Over a period of time, these naturally occurring lipids form interfacial coatings that modify the wettability characteristics of these foreign synthetic surfaces. In this study, we examine the deposition and consequences of tear film lipids on silicone hydrogel (SiHy) contact lenses. We use bovine meibum, which is a complex mixture of waxy esters, cholesterol esters, and lipids that is secreted from the meibomian glands located on the upper and lower eyelids of mammals. For comparison, we study two commercially available model materials: dipalmitoylphosphatidylcholine (DPPC) and cholesterol. Upon deposition, we find that DPPC and meibum remain closer to the SiHy surface than cholesterol, which diffuses further into the porous SiHy matrix. In addition, we also monitor the fate of unstable thin liquid films that consequently rupture and dewet on these lipid-decorated surfaces. This dewetting provides valuable qualitative and quantitative information about the wetting characteristics of these SiHy substrates. We observe that decorating the SiHy surface with simple model lipids such as DPPC and cholesterol increases the hydrophilicity, which consequently inhibits dewetting, whereas meibum behaves conversely.

  3. Effect of radiation light characteristics on surface hardness of paint-on resin for shade modification.

    PubMed

    Arikawa, Hiroyuki; Kanie, Takahito; Fujii, Koichi; Ban, Seiji

    2005-12-01

    The purpose of this study was to investigate the effect of radiation light characteristics--of different types of clinical light-curing unit--on polymerization efficiency, as determined by the surface hardness of light-cured paint-on resins. Four shades of paint-on resin for shade modification of restorative resins were used. Materials were cured using one laboratory and three clinical light-curing units with different light sources, namely tungsten-halogen, LED, plasma arc, and xenon flash lamps. Knoop hardness measurements were taken at both the top and bottom surfaces of the specimens to assess the mechanical properties and degree of polymerization. Both LED and plasma arc light units caused significantly poorer surface hardness than the halogen and laboratory xenon lights. In addition, the transparent shade was more sensitive to surface hardness than other chromatic shades. Our results indicated that the polymerization efficiency of paint-on resin was significantly influenced by the radiation light characteristics of clinical light-curing units.

  4. Surface transfer doping induced effective modulation on ambipolar characteristics of few-layer black phosphorus

    NASA Astrophysics Data System (ADS)

    Xiang, Du; Han, Cheng; Wu, Jing; Zhong, Shu; Liu, Yiyang; Lin, Jiadan; Zhang, Xue-Ao; Ping Hu, Wen; Özyilmaz, Barbaros; Neto, A. H. Castro; Wee, Andrew Thye Shen; Chen, Wei

    2015-03-01

    Black phosphorus, a fast emerging two-dimensional material, has been configured as field effect transistors, showing a hole-transport-dominated ambipolar characteristic. Here we report an effective modulation on ambipolar characteristics of few-layer black phosphorus transistors through in situ surface functionalization with caesium carbonate (Cs2CO3) and molybdenum trioxide (MoO3), respectively. Cs2CO3 is found to strongly electron dope black phosphorus. The electron mobility of black phosphorus is significantly enhanced to ~27 cm2 V-1 s-1 after 10 nm Cs2CO3 modification, indicating a greatly improved electron-transport behaviour. In contrast, MoO3 decoration demonstrates a giant hole-doping effect. In situ photoelectron spectroscopy characterization reveals significant surface charge transfer occurring at the dopants/black phosphorus interfaces. Moreover, the surface-doped black phosphorus devices exhibit a largely enhanced photodetection behaviour. Our findings coupled with the tunable nature of the surface transfer doping scheme ensure black phosphorus as a promising candidate for further complementary logic electronics.

  5. Cellular form of prion protein inhibits Reelin-mediated shedding of Caspr from the neuronal cell surface to potentiate Caspr-mediated inhibition of neurite outgrowth.

    PubMed

    Devanathan, Vasudharani; Jakovcevski, Igor; Santuccione, Antonella; Li, Shen; Lee, Hyun Joon; Peles, Elior; Leshchyns'ka, Iryna; Sytnyk, Vladimir; Schachner, Melitta

    2010-07-07

    Extension of axonal and dendritic processes in the CNS is tightly regulated by outgrowth-promoting and -inhibitory cues to assure precision of synaptic connections. We identify a novel role for contactin-associated protein (Caspr) as an inhibitory cue that reduces neurite outgrowth from CNS neurons. We show that proteolysis of Caspr at the cell surface is regulated by the cellular form of prion protein (PrP), which directly binds to Caspr. PrP inhibits Reelin-mediated shedding of Caspr from the cell surface, thereby increasing surface levels of Caspr and potentiating the inhibitory effect of Caspr on neurite outgrowth. PrP deficiency results in reduced levels of Caspr at the cell surface, enhanced neurite outgrowth in vitro, and more efficient regeneration of axons in vivo following spinal cord injury. Thus, we reveal a previously unrecognized role for Caspr and PrP in inhibitory modulation of neurite outgrowth in CNS neurons, which is counterbalanced by the proteolytic activity of Reelin.

  6. Effect of surface modification by nitrogen ion implantation on the electrochemical and cellular behaviors of super-elastic NiTi shape memory alloy.

    PubMed

    Maleki-Ghaleh, H; Khalil-Allafi, J; Sadeghpour-Motlagh, M; Shakeri, M S; Masoudfar, S; Farrokhi, A; Beygi Khosrowshahi, Y; Nadernezhad, A; Siadati, M H; Javidi, M; Shakiba, M; Aghaie, E

    2014-12-01

    The aim of this investigation was to enhance the biological behavior of NiTi shape memory alloy while preserving its super-elastic behavior in order to facilitate its compatibility for application in human body. The surfaces of NiTi samples were bombarded by three different nitrogen doses. Small-angle X-ray diffraction was employed for evaluating the generated phases on the bombarded surfaces. The electrochemical behaviors of the bare and surface-modified NiTi samples were studied in simulated body fluid (SBF) using electrochemical impedance and potentio-dynamic polarization tests. Ni ion release during a 2-month period of service in the SBF environment was evaluated using atomic absorption spectrometry. The cellular behavior of nitrogen-modified samples was studied using fibroblast cells. Furthermore, the effect of surface modification on super-elasticity was investigated by tensile test. The results showed the improvement of both corrosion and biological behaviors of the modified NiTi samples. However, no significant change in the super-elasticity was observed. Samples modified at 1.4E18 ion cm(-2) showed the highest corrosion resistance and the lowest Ni ion release.

  7. Virtual Surface Characteristics of a Tactile Display Using Magneto-Rheological Fluids

    PubMed Central

    Lee, Chul-Hee; Jang, Min-Gyu

    2011-01-01

    Virtual surface characteristics of tactile displays are investigated to characterize the feeling of human touch for a haptic interface application. In order to represent the tactile feeling, a prototype tactile display incorporating Magneto-Rheological (MR) fluid has been developed. Tactile display devices simulate the finger’s skin to feel the sensations of contact such as compliance, friction, and topography of the surface. Thus, the tactile display can provide information on the surface of an organic tissue to the surgeon in virtual reality. In order to investigate the compliance feeling of a human finger’s touch, normal force responses of a tactile display under various magnetic fields have been assessed. Also, shearing friction force responses of the tactile display are investigated to simulate the action of finger dragging on the surface. Moreover, different matrix arrays of magnetic poles are applied to form the virtual surface topography. From the results, different tactile feelings are observed according to the applied magnetic field strength as well as the arrays of magnetic poles combinations. This research presents a smart tactile display technology for virtual surfaces. PMID:22163769

  8. Influence of ground surface characteristics on the mean radiant temperature in urban areas

    NASA Astrophysics Data System (ADS)

    Lindberg, Fredrik; Onomura, Shiho; Grimmond, C. S. B.

    2016-09-01

    The effect of variations in land cover on mean radiant temperature ( T mrt ) is explored through a simple scheme developed within the radiation model SOLWEIG. Outgoing longwave radiation is parameterised using surface temperature observations on a grass and an asphalt surface, whereas outgoing shortwave radiation is modelled through variations in albedo for the different surfaces. The influence of ground surface materials on T mrt is small compared to the effects of shadowing. Nevertheless, altering ground surface materials could contribute to a reduction in T mrt to reduce the radiant load during heat-wave episodes in locations where shadowing is not an option. Evaluation of the new scheme suggests that despite its simplicity it can simulate the outgoing fluxes well, especially during sunny conditions. However, it underestimates at night and in shadowed locations. One grass surface used to develop the parameterisation, with very different characteristics compared to an evaluation grass site, caused T mrt to be underestimated. The implications of using high temporal resolution (e.g. 15 minutes) meteorological forcing data under partly cloudy conditions are demonstrated even for fairly proximal sites.

  9. Dropwise Evaporative Cooling of Heated Surfaces with Various Wettability Characteristics Obtained by Nanostructure Modifications

    NASA Astrophysics Data System (ADS)

    Chen, Jian-nan; Zhang, Zhen; Ouyang, Xiao-long; Jiang, Pei-xue

    2016-03-01

    A numerical and experimental investigation was conducted to analyze dropwise evaporative cooling of heated surfaces with various wettability characteristics. The surface wettability was tuned by nanostructure modifications. Spray-cooling experiments on these surfaces show that surfaces with better wettability have better heat transfer rate and higher critical heat flux (CHF). Single droplet impingement evaporative cooling of a heated surface was then investigated numerically with various wettability conditions to characterize the effect of contact angle on spray-cooling heat transfer. The volume of fluid (VOF) model with variable-time stepping was used to capture the time-dependent liquid-gas interface motion throughout the computational domain with the kinetic theory model used to predict the evaporation rate at the liquid-gas interface. The numerical results agree with the spray-cooling experiments that dropwise evaporative cooling is much better on surfaces with better wettability because of the better liquid spreading and convection, better liquid-solid contact, and stronger liquid evaporation.

  10. Dropwise Evaporative Cooling of Heated Surfaces with Various Wettability Characteristics Obtained by Nanostructure Modifications.

    PubMed

    Chen, Jian-Nan; Zhang, Zhen; Ouyang, Xiao-Long; Jiang, Pei-Xue

    2016-12-01

    A numerical and experimental investigation was conducted to analyze dropwise evaporative cooling of heated surfaces with various wettability characteristics. The surface wettability was tuned by nanostructure modifications. Spray-cooling experiments on these surfaces show that surfaces with better wettability have better heat transfer rate and higher critical heat flux (CHF). Single droplet impingement evaporative cooling of a heated surface was then investigated numerically with various wettability conditions to characterize the effect of contact angle on spray-cooling heat transfer. The volume of fluid (VOF) model with variable-time stepping was used to capture the time-dependent liquid-gas interface motion throughout the computational domain with the kinetic theory model used to predict the evaporation rate at the liquid-gas interface. The numerical results agree with the spray-cooling experiments that dropwise evaporative cooling is much better on surfaces with better wettability because of the better liquid spreading and convection, better liquid-solid contact, and stronger liquid evaporation.

  11. [Residue characteristics and distributions of perfluorinated compounds in surface seawater along Shenzhen coastline].

    PubMed

    Chen, Qing-Wu; Zhang, Hong; Chai, Zhi-Fang; Shen, Jin-Can; Yang, Bo

    2012-06-01

    In order to explore the residue characteristics and distributions of 15 perfluorinated compounds (PFCs) in 18 surface seawater samples along Shenzhen coastline, high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) combined with solid phase extraction enrichment was applied in this research. The results indicated that residue level of PFCs in coastal surface seawater samples was significantly affected by human activities. Sigma PFCs residue levels in surface seawater from Shenzhen west coast, which locates below the estuary of Pearl River and Donghao River, are much higher than those from the east coast, which has low development and sparse population (P<0.05). Under natural conditions, sigma PFCs residue levels in coastal surface seawater samples from Shenzhen Bays are higher than those out of bays. The major residue species in surface seawater samples along Shenzhen coast were medium- and short-chain PFCs, including perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorohexanoic acid and perfluoropentanoic acid. Their similar environmental behavior (P<0.05, P<0.01) is likely associated with the production process of PFCs-related products. Furthermore, cluster analysis results show that PFOS (R2 = 0.4092) level can be used as a representative parameter for evaluating PFCs contamination status in surface seawater along Shenzhen coast.

  12. [Characteristics and numerical simulation of surface albedo in temperate desert steppe in Inner Mongolia].

    PubMed

    Yang, Fu-lin; Zhou, Guang-sheng; Zhang, Feng; Wang, Feng-yu; Bao, Fang; Ping, Xiao-yan

    2009-12-01

    Based on the meteorological and biological observation data from the temperate desert steppe ecosystem research station in Sunitezuoqi of Inner Mongolia during growth season (from May 1st to October 15th, 2008), the diurnal and seasonal characteristics of surface albedo in the steppe were analyzed, with related model constructed. In the steppe, the diurnal variation of surface albedo was mainly affected by solar altitude, being higher just after sunrise and before sunset and lower in midday. During growth season, the surface albedo was from 0.20 to 0.34, with an average of 0.25, and was higher in May, decreased in June, kept relatively stable from July to September, and increased in October. This seasonal variation was related to the phenology of canopy leaf, and affected by precipitation process. Soil water content (SWC) and leaf area index (LAI) were the key factors affecting the surface albedo. A model for the surface albedo responding to SWC and LAI was developed, which showed a good performance in consistent between simulated and observed surface albedo.

  13. Distribution and Pollution Characteristics Analysis of Heavy Metals in Surface Sediment in Bi River

    NASA Astrophysics Data System (ADS)

    Huang, Qianrui; Danek, Tomas; Cheng, Xianfeng; Dong, Tao; Qi, Wufu; Zou, Liling; Zhao, Xueqiong; Zhao, Xinliang; Xiang, Yungang

    2016-10-01

    The author analyzes distribution characteristics of heavy metals’ content in surface sediments of Bi River (Cu, Zn, As and Cd) and evaluates the potential ecological harm of heavy metal pollution in surface sediment by index method of potential ecological harm. Results show that heavy metals, such as Cu, Zn, As, Pb and Cd in surface sediments of Bi River are badly out of limitation. Especially, the heavy metals’ content in Jinding mining area is far higher than the national first class standard. The content of heavy metal is still high in the intersection of Bi River and Lancang River, which have certain influence on the Lancang River sediment and its water system. And, Pb and Cd, as the main pollutants, should be regarded as a key research subject.

  14. Surface roughness of sea ice in Fram Strait - A characteristic of the ice-atmosphere interface

    NASA Astrophysics Data System (ADS)

    Yearsley, W. A.; Herzfeld, U. C.; McDonald, B.; Wallin, B. F.; Maslanik, J. A.; Fladeland, M. M.; Long, D. G.; Crocker, R. I.

    2012-12-01

    Surface roughness is an important characteristic of the interface between the lower atmosphere and the sea ice. In this paper, we present observational and mathematical methods that yield surface roughness length at centimeter to kilometer scales along transects of several hundred kilometers in Fram Strait. During the Characterization of Arctic Sea Ice Experiment (CASIE, July-August 2009), centimeter-scale laser profilometer data and microASAR data were collected from unmanned aircraft, the SIERRA of NASA's Ames Research Center. After correction for altitude using GPS data, aerodynamic roughness length is derived using patial classification parameters and geometric surface properties. Statistical distributions of ridges in sea-ice are calculated. The roughness-based parameters have several uses in modeling energy flux between ocean, ice and boundary layer and in modeling ridging processes in sea ice.

  15. Calculation of the longitudinal aerodynamic characteristics of upper-surface-blown wing-flap configurations

    NASA Technical Reports Server (NTRS)

    Mendenhall, M. R.; Spangler, S. B.

    1979-01-01

    An investigation has been carried out to develop an engineering method for predicting the longitudinal aerodynamic characteristics of wing-flap configurations with upper surface blown (USB) high lift devices. Potential flow models of the lifting surfaces and the jet wakes are combined to calculate the induced interference of the engine wakes on the wing and flaps. The wing may have an arbitrary planform with camber and twist and multiple trailing edge flaps. The jet wake model has a rectangular cross section over its entire length and it is positioned such that the wake is tangent to the upper surfaces of the wing and flaps. Comparisons of measured and predicted pressure distributions, spanload distributions, and total lift and pitching-moment coefficients on swept and unswept USB configurations are presented for a wide range of thrust coefficients and flap deflection angles.

  16. Scaling evaluation of the effect of surface characteristics on potential for deep convection over uniform terrain

    NASA Technical Reports Server (NTRS)

    Segal, M.; Arritt, R. W.; Clark, C.; Rabin, R.; Brown, J.

    1995-01-01

    The effect of surface characteristics on the daytime change in the potential for development of deep convection resulting from surface flux of heat and moisture is evaluated by conceptual, scaling, and numerical modeling approaches. It is shown that deep convection depends significantly on the Bowen ratio; for smaller Bowen ratio, the thermodynamic potential for deep convection increases. The elevation and the intensity of the capping stable layer have an opposing impact on deep convection: increasing moisture accumulation through evapotranspiration was supportive but was counteracted by the enhancement of dry entrainment. Based on an approximnate treatment of the effect of cloudiness on solar irradiance, it was found that development of fair weather cumulus has a secondary effect on deep convection potential. Observational and operational aspects of the influence of surface conditions on evapotranspiration and development of deep convection are presented.

  17. Simplified fabrication of back surface electric field silicon cells and novel characteristics of such cells

    NASA Technical Reports Server (NTRS)

    Mandelkorn, J.; Lamneck, J. H., Jr.

    1972-01-01

    An investigation of the characteristics and behavior of 10 ohm-cm silicon cells having abnormally high open-circuit voltages was made. The cells studied were made by a new, highly simplified, contact fabrication process which creates both a contact and a thin electric field region at the cell back surface without the need for phosphorus layer removal. These cells had open-circuit voltages of about 0.58 V and their performance as a function of thickness, temperature, and 1 MeV electron irradiation is detailed. The study showed that 10 ohm-cm back-surface-field cells can have the high initial efficiencies and desirable temperature behavior of low resistivity cells. Thin back-surface-field cells were made and showed, in addition, much greater radiation damage resistance. A mechanism is proposed to explain the results.

  18. Simplified fabrication of back surface electric field silicon cells and novel characteristics of such cells.

    NASA Technical Reports Server (NTRS)

    Mandelkorn, J.; Lamneck, J. H., Jr.

    1972-01-01

    An investigation of the characteristics and behavior of 10 ohm-cm silicon cells having abnormally high open-circuit voltages was made. The cells studied were made by a new, highly simplified, contact fabrication process which creates both a contact and a thin electric field region at the cell back surface without the need for phosphorus layer removal. These cells had open-circuit voltages of about 0.58 V and their performance as a function of thickness, temperature, and 1 MeV electron irradiation is detailed. The study showed that 10 ohm-cm back-surface-field cells can have the high initial efficiencies and desirable temperature behavior of low resistivity cells. Thin back-surface-field cells were made and showed, in addition, much greater radiation damage resistance. A mechanism is proposed to explain the results.

  19. Experimental Study of Electron Emission Characteristics of a Surface Flashover Trigger in a Low Pressure Environment

    NASA Astrophysics Data System (ADS)

    Hu, Shangmao; Yao, Xueling; Chen, Jingliang

    2010-12-01

    Characteristics of electron emission induced by a surface flashover trigger device in a low-pressure trigger switch were investigated. A test method to measure the emitted charges from the trigger device was developed, and the factors affecting the emitted charges were analyzed. The results indicated that the major emitted charges from the trigger device were induced by surface plasma generated by surface flashover occurring on the trigger dielectric material. The emitted charges and the peak emission current increased linearly with the change in the trigger voltage and bias voltage. The emitted charges collected from the anode were affected by the gap distance. However, the emitted charges were less affected by the anode diameter. Furthermore, the emitted charges and the peak emission current decreased rapidly with the increase in gas pressure in a range from 0 Pa to 100 Pa, and then remained stable or changed slightly when the increase in gas pressure up to 2400 Pa.

  20. Formation and properties of surface-anchored polymer assemblies with tunable physico-chemical characteristics

    NASA Astrophysics Data System (ADS)

    Wu, Tao

    We describe two new methodologies leading to the formation of novel surface-anchored polymer assemblies on solid substrates. While the main goal is to understand the fundamentals pertaining to the preparation and properties of the surface-bound polymer assemblies (including neutral and chargeable polymers), several examples also are mentioned throughout the Thesis that point out to practical applications of such structures. The first method is based on generating assemblies comprising anchored polymers with a gradual variation of grafting densities on solid substrates. These structures are prepared by first covering the substrate with a molecular gradient of the polymerization initiator, followed by polymerization from these substrate-bound initiator centers ("grafting from"). We apply this technique to prepare grafting density gradients of poly(acryl amide) (PAAm) and poly(acrylic acid) (PAA) on silica-covered substrates. We show that using the grafting density gradient geometry, the characteristics of surface-anchored polymers in both the low grafting density ("mushroom") regime as well as the high grafting density ("brush") regime can be accessed conveniently on a single sample. We use a battery of experimental methods, including Fourier transform infrared spectroscopy (FTIR), Near-edge absorption fine structure spectroscopy (NEXAFS), contact angle, ellipsometry, to study the characteristics of the surface-bound polymer layers. We also probe the scaling laws of neutral polymer as a function of grafting density, and for weak polyelectrolyte, in addition to the grafting density, we study the affect of solution ionic strength and pH values. In the second novel method, which we coined as "mechanically assisted polymer assembly" (MAPA), we form surface anchored polymers by "grafting from" polymerization initiators deposited on elastic surfaces that have been previously extended uniaxially by a certain length increment, Deltax. Upon releasing the strain in the

  1. Seasonal transition of precipitation characteristics associated with land surface conditions in and around Bangladesh

    NASA Astrophysics Data System (ADS)

    Ono, M.; Takahashi, H. G.

    2016-10-01

    This study examined the seasonal transition of precipitation characteristics and its association with land surface conditions in and around Bangladesh, where land surface conditions are predominantly wet. Hourly rain rate data from the Global Satellite Mapping of Precipitation Microwave-Infrared Combined Product and 10 day soil moisture data from the Advanced Microwave Scanning Radiometer Earth Observing System were used over the 7 years from 2003 to 2009. Area mean values of soil moisture, and precipitation amount, frequency, and intensity were calculated for each 10 day period. Results showed that higher precipitation amount and frequency were observed over the wet soil conditions, which indicates that soil moisture was influenced by previous precipitation events. However, the soil moisture could also control the precipitation characteristics. The seasonal and interannual variations in all regions suggested that precipitation amount and frequency increased in moist soil conditions, which is associated with an increase of water vapor supplied from the moist land surface. Over a flat plain (87°E-91°E, 23°N-25°N), a higher afternoon precipitation intensity was observed over drier land surfaces. This relationship was observed on seasonal and interannual variations. This suggests that the land surface conditions in this region can affect the afternoon precipitation intensity to some extent, although changes of atmospheric conditions can be a major factor particularly for the seasonal changes. However, this relationship was not observed in mountainous regions. This can be explained by other factors, such as thermally induced local circulations by the surrounding topography, being stronger than the impact of land surface conditions.

  2. Surface characteristics of a self-polymerized dopamine coating deposited on hydrophobic polymer films.

    PubMed

    Jiang, Jinhong; Zhu, Liping; Zhu, Lijing; Zhu, Baoku; Xu, Youyi

    2011-12-06

    This study aims to explore the fundamental surface characteristics of polydopamine (pDA)-coated hydrophobic polymer films. A poly(vinylidene fluoride) (PVDF) film was surface modified by dip coating in an aqueous solution of dopamine on the basis of its self-polymerization and strong adhesion feature. The self-polymerization and deposition rates of dopamine on film surfaces increased with increasing temperature as evaluated by both spectroscopic ellipsometry and scanning electronic microscopy (SEM). Changes in the surface morphologies of pDA-coated films as well as the size and shape of pDA particles in the solution were also investigated by SEM, atomic force microscopy (AFM), and transmission electron microscopy (TEM). The surface roughness and surface free energy of pDA-modified films were mainly affected by the reaction temperature and showed only a slight dependence on the reaction time and concentration of the dopamine solution. Additionally, three other typical hydrophobic polymer films of polytetrafluoroethylene (PTFE), poly(ethylene terephthalate) (PET), and polyimide (PI) were also modified by the same procedure. The lyophilicity (liquid affinity) and surface free energy of these polymer films were enhanced significantly after being coated with pDA, as were those of PVDF films. It is indicated that the deposition behavior of pDA is not strongly dependent on the nature of the substrates. This information provides us with not only a better understanding of biologically inspired surface chemistry for pDA coatings but also effective strategies for exploiting the properties of dopamine to create novel functional polymer materials.

  3. Designing and preparation of cytisine alkaloid surface-imprinted material and its molecular recognition characteristics

    NASA Astrophysics Data System (ADS)

    Gao, Baojiao; Bi, Concon; Fan, Li

    2015-03-01

    Based on molecular design, a cytisine surface-imprinted material was prepared using the new surface-imprinting technique of "pre-graft polymerizing and post-imprinting". The graft-polymerization of glycidyl methacrylate (GMA) on the surfaces of micron-sized silica gel particles was first performed with a surface-initiating system, preparing the grafted particles PGMA/SiO2. Subsequently, a polymer reaction, the ring-opening reaction of the epoxy groups of the grafted PGMA, was conducted with sodium 2,4-diaminobenzene sulfonate (SAS) as reagent, resulting in the functional grafted particles SAS-PGMA/SiO2. The adsorption of cytisine on SAS-PGMA/SiO2 particles reached saturation via strong electrostatic interaction between the sulfonate groups of SAS-PGMA/SiO2 particles and the protonated N atoms in cytisine molecule. Finally, cytisine surface-imprinting was successfully carried out with glutaraldehyde as crosslinker, obtaining cytisine surface-imprinted material MIP-SASP/SiO2. The binding and recognition characteristics of MIP-SASP/SiO2 towards cytisine were investigated in depth. The experimental results show that there is strong electrostatic interaction between particles and cytisine molecules, and on this basis, cytisine surface-imprinting can be smoothly performed. The surface-imprinted MIP-SASP/SiO2 has special recognition selectivity and excellent binding affinity for cytisine, and the selectivity coefficients of MIP-SASP/SiO2 particles for cytisine relative to matrine and oxymatrine, which were used as two contrast alkaloids, are 9.5 and 6.5, respectively.

  4. Molecular and cellular interactions between intoplicine, DNA, and topoisomerase II studied by surface-enhanced Raman scattering spectroscopy.

    PubMed

    Morjani, H; Riou, J F; Nabiev, I; Lavelle, F; Manfait, M

    1993-10-15

    The surface-enhanced Raman scattering spectra of the new antitumoral agent, intoplicine (RP 60475, NSC 645008), and those of its complexes with DNA and topoisomerase II in vitro and in K562 cancer cells were obtained. Intoplicine was found to unwind DNA and to inhibit purified calf thymus topoisomerase II via a stabilization of the ternary cleavable complex. The intensity of the surface-enhanced Raman scattering spectrum of intoplicine was not modified by the addition of plasmid pBR322 or calf thymus DNA. In the complex of this antitumor agent with topoisomerase II, the signal of intoplicine was completely abolished, indicating that at least some portion of intoplicine binds to an internal part of the enzyme. During the formation of the ternary complex, intoplicine was released from the interior of the protein and formed hydrogen bonds via its hydroxyl and/or amino groups. Similar modifications of the intoplicine spectra were found by microsurface-enhanced Raman scattering spectroscopy of the compound in the nucleus of treated K562 cells. In contrast, intoplicine was found to be in a free form in the cytoplasm.

  5. Nanogrooved surface-patterns induce cellular organization and axonal outgrowth in neuron-like PC12-cells.

    PubMed

    Klymov, Alexey; Rodrigues Neves, Charlotte T; te Riet, Joost; Agterberg, Martijn J H; Mylanus, Emmanuel A M; Snik, Ad F M; Jansen, John A; Walboomers, X Frank

    2015-02-01

    Modulation of a materials surface topography can be used to steer various aspects of adherent cell behaviour, such as cell directional organization. Especially nanometric sized topographies, featuring sizes similar to for instance the axons of the spiral ganglion cells, are interesting for such purpose. Here, we utilized nanosized grooves in the range of 75-500 nm, depth of 30-150 nm, and pitches between 150 nm and 1000 nm for cell culture of neuron-like PC12 cells. The organizational behaviour was evaluated after 7 days of culture by bright field and scanning electron microscopy. Nanotopographies were shown to induce aligned cell-body/axon orientation and an increased axonal outgrowth. Our findings suggest that a threshold for cell body alignment of neuronal cells exists on grooved topographies with a groove width of 130 nm, depth of 70 nm and pitch of 300 nm, while axon alignment can already be induced by grooves with 135 nm width, 52 nm depth and 200 nm pitch. However, no threshold has been found for axonal outgrowth, as all of the used patterns increased outgrowth of PC12-axons. In conclusion, surface nanopatterns have the potential to be utilized as an electrode modification for a stronger separation of cells, and can be used to direct cells towards the electrode contacts of cochlear implants.

  6. Physical characteristics of a lava flow determined from thermal measurements at the lava's surface

    NASA Astrophysics Data System (ADS)

    Ismail-Zadeh, A. T.; Kovtunov, D. A.; Korotkii, A. I.; Melnik, O. E.; Tsepelev, I. A.

    2016-04-01

    We consider the problem about determination of characteristics of a lava flow from the physical parameters measured on its surface. The problem is formulated as an inverse boundary problem for the model simulating the dynamics of a viscous heat-conducting incompressible inhomogeneous fluid, where, on the basis of additional data at one part of the model boundary, the missing conditions at another part of the boundary have to be determined, and then the characteristics of fluid in the entire model domain have to be reconstructed. The considered problem is ill-posed. We develop a numerical approach to the solution of the problem in the case of a steady-state flow. Assuming that the temperature and the heat flow are known at the upper surface of the lava, we determine the flow characteristics inside the lava. We compute model examples and show that the lava temperature and flow velocity can be determined with a high precision when the initial data are smooth or slightly noisy.

  7. Surface Tension Prediction Using Characteristics of the Density Profile Through the Interfacial Region

    NASA Astrophysics Data System (ADS)

    Wemhoff, A. P.; Carey, V. P.

    2006-03-01

    A simple surface tension estimation technique is described that is based solely upon the characteristics of the density profile in the interfacial region and the physical properties of the molecules in the fluid. This method, denoted free energy integration (FEI), links interfacial tension to known interfacial region density profile characteristics obtained via experiment or simulation. The general FEI methodology is provided here, and specific relations are derived for a methodology that incorporates the Redlich-Kwong fluid model. The Redlich-Kwong based FEI method was used to predict interfacial tension using the density profile characteristics of molecular dynamics (MD) simulations of argon using the Lennard-Jones potential, diatomic nitrogen using the two-center Lennard-Jones potential, and water using the extended simple point-charge (SPC/E) model. These results for argon compare favorably to values calculated by the traditional virial approach, known values from the literature using the finite-size scaling technique, and ASHRAE recommended values. In addition, the FEI predictions agree well with ASHRAE values and predictions using the virial method for nitrogen for the simulated range of temperatures in this study, and for water for reduced temperatures above 0.7. In addition, the FEI method results agree well with other established theoretical techniques for predictions of the surface tension of sulfur hexafluoride close to the critical point.

  8. Simultaneous measurements of shape characteristics and radar backscattering of a water surface in a rain field

    NASA Astrophysics Data System (ADS)

    Liu, Ren; Liu, Xinan; Duncan, James H.

    2015-11-01

    The characteristics of radar backscattering from a water surface that is stimulated by a rain field are studied at laboratory scale. The experiment is carried out in a 1.22-m by 1.22-m water pool with a water depth of 0.3 m. Simulated raindrops are generated by an array of 22-gauge needles that are attached to the bottom of a water reservoir located above the pool. A two-dimensional horizontal translational motion is added to the water reservoir in order to vary the drop impact location for each needle during each experimental run. A cinematic Laser-Induced-Florescence (LIF) technique is used to measure the water surface shape while radar backscattering from the water surface is simultaneously recorded by a dual-polarized, ultra-wide band radar. Both the radar return intensity and the water surface shape are measured for a range of rain rates and a range of radar incidence angles. The relationship between the geometric features of the water surface shape and the radar return are explored. The support of the National Science Foundation, Division of Atmospheric and Oceanic Sciences, under grant ARC0962107 is gratefully acknowledged.

  9. Surface characteristics and damage distributions of diamond wire sawn wafers for silicon solar cells

    SciTech Connect

    Sopori, Bhushan; Devayajanam, Srinivas; Basnyat, Prakash

    2016-01-01

    This paper describes surface characteristics, in terms of its morphology, roughness and near-surface damage of Si wafers cut by diamond wire sawing (DWS) of Si ingots under different cutting conditions. Diamond wire sawn Si wafers exhibit nearly-periodic surface features of different spatial wavelengths, which correspond to kinematics of various movements during wafering, such as ingot feed, wire reciprocation, and wire snap. The surface damage occurs in the form of frozen-in dislocations, phase changes, and microcracks. The in-depth damage was determined by conventional methods such as TEM, SEM and angle-polishing/defect-etching. However, because these methods only provide local information, we have also applied a new technique that determines average damage depth over a large area. This technique uses sequential measurement of the minority carrier lifetime after etching thin layers from the surfaces. The lateral spatial damage variations, which seem to be mainly related to wire reciprocation process, were observed by photoluminescence and minority carrier lifetime mapping. Our results show a strong correlation of damage depth on the diamond grit size and wire usage.

  10. Age-related leaf characteristics of surface features and ultrastructure of Dendropanax morbifera.

    PubMed

    Kim, Ki Woo; Koo, Young Kuk; Yoon, Chul Jong

    2012-02-01

    Age-related morphological and anatomical changes were investigated by light and electron microscopy with juvenile and adult leaves of Dendropanax morbifera. Most juvenile leaves were glossy and palmate with five deep and narrow lobes divided nearly to two-thirds of the leaf base. Adult leaves were thick and possessed three lobes divided nearly to half of the leaf base. Stomata were ovoid and found on the abaxial surface. The epicuticular waxes of the plant included platelets, angular rodlets and threads. Platelets were attached to the surface at various angles. Distinct angular rodlets could be found on either the adaxial or the abaxial surface. Platelets on surface undulations occurred exclusively on the abaxial surface of adult leaves. Juvenile leaves were ca. 150 μm thick and had few intercellular spaces. Adult leaves were nearly two times thicker than juvenile leaves, and showed highly vacuolated cells and large intercellular spaces. The cuticle proper was apparent on the epidermis and showed distinctly alternating lamellate structures in juvenile leaves. The epidermal cell wall of adult leaves was covered with a cuticle layer for which a lamellate structure was not found. These results suggest that the species is heteroblastic in leaf characteristics with increasing leaf age.

  11. Surface energy characteristics of zeolite embedded PVDF nanofiber films with electrospinning process

    NASA Astrophysics Data System (ADS)

    Kang, Dong Hee; Kang, Hyun Wook

    2016-11-01

    Electrospinning is a nano-scale fiber production method with various polymer materials. This technique allows simple fiber diameters control by changing the physical conditions such as applied voltage and polymer solution viscosity during the fabrication process. The electrospun polymer fibers form a thin porous film with high surface area to volume ratio. Due to these unique characteristics, it is widely used for many application fields such as photocatalyst, electric sensor, and antibacterial scaffold for tissue engineering. Filtration is one of the main applications of electrospun polymer fibers for specific application of filtering out dust particles and dehumidification. Most polymers which are commonly used in electrospinning are hard to perform the filtering and dehumidification simultaneously because of their low hygroscopic property. To overcome this obstacle, the desiccant polymers are developed such as polyacrylic acid and polysulfobetaine methacrylate. However, the desiccant polymers are generally expensive and need special solvent for electrospinning. An alternating way to solve these problems is mixing desiccant material like zeolite in polymer solution during an electrospinning process. In this study, the free surface energy characteristics of electrospun polyvinylidene fluoride (PVDF) film with various zeolite concentrations are investigated to control the hygroscopic property of general polymers. Fundamental physical property of wettability with PVDF shows hydrophobicity. The electrospun PVDF film with small weight ratio with higher than 0.1% of zeolite powder shows diminished contact angles that certifying the wettability of PVDF can be controlled using desiccant material in electrospinning process. To quantify the surface energy of electrospun PVDF films, sessile water droplets are introduced on the electrospun PVDF film surface and the contact angles are measured. The contact angles of PVDF film are 140° for without zeolite and 80° for with 5

  12. Plasmonic Nanostructured Cellular Automata

    NASA Astrophysics Data System (ADS)

    Alkhazraji, Emad; Ghalib, A.; Manzoor, K.; Alsunaidi, M. A.

    2017-03-01

    In this work, we have investigated the scattering plasmonic resonance characteristics of silver nanospheres with a geometrical distribution that is modelled by Cellular Automata using time-domain numerical analysis. Cellular Automata are discrete mathematical structures that model different natural phenomena. Two binary one-dimensional Cellular Automata rules are considered to model the nanostructure, namely rule 30 and rule 33. The analysis produces three-dimensional scattering profiles of the entire plasmonic nanostructure. For the Cellular Automaton rule 33, the introduction of more Cellular Automata generations resulted only in slight red and blue shifts in the plasmonic modes with respect to the first generation. On the other hand, while rule 30 introduced significant red shifts in the resonance peaks at early generations, at later generations however, a peculiar effect is witnessed in the scattering profile as new peaks emerge as a feature of the overall Cellular Automata structure rather than the sum of the smaller parts that compose it. We strongly believe that these features that emerge as a result adopting the different 256 Cellular Automata rules as configuration models of nanostructures in different applications and systems might possess a great potential in enhancing their capability, sensitivity, efficiency, and power utilization.

  13. Using Nano-mechanics and Surface Acoustic Wave (SAW) for Disease Monitoring and Diagnostics at a Cellular Level in Red Blood Cells

    NASA Astrophysics Data System (ADS)

    Sivanantha, Ninnuja; Ma, Charles; Collins, David J.; Sesen, Muhsincan; Brenker, Jason; Coppel, Ross L.; Neild, Adrian; Alan, Tuncay

    A popular approach to monitoring diseases and their diagnosis is through biological, pathological or immunological characterization. However, at a cellular level progression of certain diseases manifests itself through mechanical effects as well. Here, we present a method which exploits localised flow; surface acoustic wave (SAW) induced acoustic streaming in a 9 μL droplet to characterize the adhesive properties of red blood cells (healthy, gluteraldehyde treated and malaria infected) in approximately 50 seconds. Our results show a 79% difference in cell mobilization between healthy malaria infected RBCs (and a 39% difference between healthy and treated ones), indicating that the method can serve as a platform for rapid clinical diagnosis; where separation of two or more different cell populations in a mixed solution is desirable. It can also act as a key biomarker for monitoring some diseases offering quantitative measures of disease progression and response to therapy.

  14. Determination of control-surface characteristics from NACA plain-flap and tab data

    NASA Technical Reports Server (NTRS)

    Ames, Milton B; Sears, Richard I

    1941-01-01

    The data from previous NACA pressure-distribution investigations of plain flaps and tabs with sealed gaps have been analyzed and are presented in this paper in a form readily applicable to the problems of control-surface design. The experimentally determined variation of aerodynamic parameters with flap chord and tab chord are given in chart form and comparisons are made with the theory. With the aid of these charts and the theoretical relationships for a thin airfoil, the aerodynamic characteristics for control surfaces of any plan form with plain flaps and tabs with sealed gaps may be determined. A discussion of the basic equations of the thin-airfoil theory and the development of a number of additional equations that will be helpful in tail design are presented in the appendixes. The procedure for applying the data is described and a sample problem of horizontal tail design is included. The data presented and the method of application set forth in this report should provide a reasonably accurate and satisfactory means of computing the aerodynamic characteristics of control surfaces.

  15. Responses of herbaceous plants to urban air pollution: effects on growth, phenology and leaf surface characteristics.

    PubMed

    Honour, Sarah L; Bell, J Nigel B; Ashenden, Trevor W; Cape, J Neil; Power, Sally A

    2009-04-01

    Vehicle exhaust emissions are a dominant feature of urban environments and are widely believed to have detrimental effects on plants. The effects of diesel exhaust emissions on 12 herbaceous species were studied with respect to growth, flower development, leaf senescence and leaf surface wax characteristics. A diesel generator was used to produce concentrations of nitrogen oxides (NO(x)) representative of urban conditions, in solardome chambers. Annual mean NO(x) concentrations ranged from 77 nl l(-l) to 98 nl l(-1), with NO:NO(2) ratios of 1.4-2.2, providing a good experimental simulation of polluted roadside environments. Pollutant exposure resulted in species-specific changes in growth and phenology, with a consistent trend for accelerated senescence and delayed flowering. Leaf surface characteristics were also affected; contact angle measurements indicated changes in surface wax structure following pollutant exposure. The study demonstrated clearly the potential for realistic levels of vehicle exhaust pollution to have direct adverse effects on urban vegetation.

  16. The effects of droplet characteristics on the surface features in a rain field

    NASA Astrophysics Data System (ADS)

    Liu, R.; Brown, H.; Liu, X.; Duncan, J. H.

    2013-11-01

    The characteristics of the shape of a water surface in response to the impact of simulated raindrops are studied experimentally in a 1.22-m-by-1.22-m water pool with a water depth of 0.3 m. A rain generator consisting of an open-surface water tank with an array of 22-gauge hypodermic needles (typical needle-to-needle spacing of about L0 = 3 . 5 cm) attached to holes in the tank bottom is mounted 2 m above the water pool. The tank is connected to a 2D translation stage to provide a small-radius (surface features, including the crown, stalk and ring waves, due to the impacts of the drops are measured with a cinematic laser-induced- fluorescence (LIF) technique. The dependence of these features on the rain characteristics are discussed. The support of the National Science Foundation, Division of Ocean Sciences, and the assistance of Mr. Larry Gong are gratefully acknowledged.

  17. In vitro antigen-induced antibody responses to hepatitis B surface antigen in man. Kinetic and cellular requirements.

    PubMed Central

    Cupps, T R; Gerin, J L; Purcell, R H; Goldsmith, P K; Fauci, A S

    1984-01-01

    In this report we define the parameters of the human immune response after immunization with hepatitis B vaccine. 2 wk after booster immunization, there is significant spontaneous secretion of antibody to hepatitis B surface antigen (anti-HBs IgG), which is not further augmented by stimulation with antigen or pokeweed mitogen (PWM). By 4 wk there is little spontaneous secretion of specific antibody, and low doses of antigen or PWM produce significant increases in the amount of anti-HBs IgG produced. By 8 wk the peripheral blood mononuclear cells are refractory to stimulation by antigen, but anti-HBs IgG is produced in response to PWM. 0.5 yr or more after the last immunization, some individuals will manifest an antigen-induced specific antibody response. This induction of anti-HBs IgG by hepatitis B surface antigen (HBsAg) is monocyte- and T cell-dependent. Note that there is a dichotomy in the T cell response to HBsAg. The specific antibody response is clearly T cell dependent, but no in vitro T cell proliferative response to HBsAG could be demonstrated in the immunized individuals. Although the precise reason for the absent proliferative response to HBsAg despite well-established humoral immunity has not been determined, there was no evidence to suggest nonspecific suppression by HBsAg or the presence of an adherent suppressor cell population. The ability to evaluate antigen-induced, antigen-specific responses to HBsAg will be useful in defining the unique interaction between the human immune response and this clinically important viral agent. PMID:6332826

  18. Soil-geomorphic significance of land surface characteristics in an arid mountain range, Mojave Desert, USA

    USGS Publications Warehouse

    Hirmas, D.R.; Graham, R.C.; Kendrick, K.J.

    2011-01-01

    Mountains comprise an extensive and visually prominent portion of the landscape in the Mojave Desert, California. Landform surface properties influence the role these mountains have in geomorphic processes such as dust flux and surface hydrology across the region. The primary goal of this study was to describe and quantify land surface properties of arid-mountain landforms as a step toward unraveling the role these properties have in soil-geomorphic processes. As part of a larger soil-geomorphic study, four major landform types were identified within the southern Fry Mountains in the southwestern Mojave Desert on the basis of topography and landscape position: mountaintop, mountainflank, mountainflat (intra-range low-relief surface), and mountainbase. A suite of rock, vegetation, and morphometric land surface characteristic variables was measured at each of 65 locations across the study area, which included an associated piedmont and playa. Our findings show that despite the variation within types, landforms have distinct land surface properties that likely control soil-geomorphic processes. We hypothesize that surface expression influences a feedback process at this site where water transports sediment to low lying areas on the landscape and wind carries dust and soluble salts to the mountains where they are washed between rocks, incorporated into the soil, and retained as relatively long-term storage. Recent land-based video and satellite photographs of the dust cloud emanating from the Sierra Cucapá Mountains in response to the 7.2-magnitude earthquake near Mexicali, Mexico, support the hypothesis that these landforms are massive repositories of dust.

  19. Surface ultrastructural characteristics of Dictyocotyle coeliaca Nybelin, 1941 (Monopisthocotylea: Monocotylidae), an endoparasitic monogenean of rays.

    PubMed

    Poddubnaya, Larisa G; Hemmingsen, Willy; Gibson, David I

    2016-03-01

    Scanning and transmission electron microscopical observations were made of the surface topography of Dictyocotyle coeliaca (Nybelin, 1941) (Monopisthocotylea: Monocotylidae), a unique endoparasitic monogenean from the body cavity of the ray Amblyraja radiata (Elasmobranchii: Rajidae). Scanning investigation show the presence on the ventral side of the anterior body of smooth areas with pit-like depressions and shallow ridges, whereas the tegument of the middle and posterior regions of the body is extensively folded, and on the dorsal surface the tegument is smooth but interrupted by deep depressions. Transmission observation revealed the presence of invaginations of varying irregularity and depth, which form the various depressions of the tegumental surface. Non-ciliated, dome-shaped papillae occur singly or in groups and are common around the mouth and both the genital and vaginal pores, but exhibit no particular orientation. The haptor is much reduced, compared with that of ectoparasitic monocotylids, and is covered ventrally with an irregular array of 40-70 shallow loculi. Internal differences occur in the thickness of the syncytial tegumentary layer of the haptoral loculi and septa and also in the number of cytoplasmic inclusions. The locular surface has distinct ultrastructural characteristics, the most obvious of which are a honeycomb arrangement of small pockets measuring 0.6 × 0.75 to 1.0 × 1.7 μm in diameter, a terminal web beneath the surface plasma membrane and large outgrowths on the surface of the loculi filled with lysosome-like bodies. The surface specializations of the body and haptoral tegument of D. coeliaca are discussed in relation to their being adaptations to an endoparasitic environment.

  20. Trailing edge wake flow characteristics of upper surface blown configurations. [noise generators

    NASA Technical Reports Server (NTRS)

    Reddy, N. N.

    1978-01-01

    Mean and fluctuating flow characteristics in the wake of upper surface blown flap configurations are presented. Relative importance of the longitudinal and the transverse components of the wake flow turbulence for noise generation are evaluated using correlation between the near-field noise and the wake turbulence. Effects of the jet velocity, the initial turbulence in the jet, and the flap deflection angle on noise and wake flow characteristics are studied. The far-field noise data is compared with the existing empirical prediction method. The measured wake flow properties are compared with an analytical model used in the existing USB wake flow noise theory. The detailed wake flow profiles, wake flow turbulence space-time correlations, wake flow turbulence cross-power spectra, and near-field noise third octave band spectra are presented in the appendices.

  1. Synthesis, solubilization, and surface functionalization of highly fluorescent quantum dots for cellular targeting through a small molecule

    NASA Astrophysics Data System (ADS)

    Galloway, Justin F.

    To achieve long-term fluorescence imaging with quantum dots (QDs), a CdSe core/shell must first be synthesized. The synthesis of bright CdSe QDs is not trivial and as a consequence, the role of surfactant in nucleation and growth was investigated. It was found that the type of surfactant used, either phosphonic or fatty acid, played a pivotal role in the size of the CdSe core. The study of surfactant on CdSe synthesis, ultimately led to an electrical passivation method that utilized a short-chained phosphonic acid and highly reactive organometallic precursors to achieve high quantum yield (QY) as has been previously described. The synthesis of QDs using organometallic precursors and a phosphonic acid for passivation resulted in 4 out of 9 batches of QDs achieving QYs greater than 50% and 8 out of 9 batches with QYs greater than 35%. The synthesis of CdSe QDs was done in organic solutions rendering the surface of the particle hydrophobic. To perform cell-targeting experiments, QDs must be transferred to water. The transfer of QDs to water was successfully accomplished by using single acyl chain lipids. A systematic study of different lipid combinations and coatings demonstrated that 20-40 mol% single acyl chained lipids were able to transfer QDs to water resulting in monodispersed, stable QDs without adversely affecting the QY. The advantage to water solubilization using single acyl chain lipids is that the QD have a hydrodynamic radius less than 15 nm, QYs that can exceed 50% and additional surface functionalization can be down using the reactive sites incorporated into the lipid bilayer. QDs that are bright and stable in water were studied for the purpose of targeting G protein-coupled Receptors (GPCR). GPCRs are transmembrane receptors that internalize extracellular cues, and thus mediate signal transduction. The cyclic Adenosine Monophosphate Receptor 1 of the model organism Dictyostelium disodium was the receptor of interest. The Halo protein, a genetically

  2. Study of Osteoclast Adhesion to Cortical Bone Surfaces: A Correlative Microscopy Approach for Concomitant Imaging of Cellular Dynamics and Surface Modifications

    PubMed Central

    2015-01-01

    Bone remodeling relies on the coordinated functioning of osteoblasts, bone-forming cells, and osteoclasts, bone-resorbing cells. The effects of specific chemical and physical bone features on the osteoclast adhesive apparatus, the sealing zone ring, and their relation to resorption functionality are still not well-understood. We designed and implemented a correlative imaging method that enables monitoring of the same area of bone surface by time-lapse light microscopy, electron microscopy, and atomic force microscopy before, during, and after exposure to osteoclasts. We show that sealing zone rings preferentially develop around surface protrusions, with lateral dimensions of several micrometers, and ∼1 μm height. Direct overlay of sealing zone rings onto resorption pits on the bone surface shows that the rings adapt to pit morphology. The correlative procedure presented here is noninvasive and performed under ambient conditions, without the need for sample labeling. It can potentially be applied to study various aspects of cell-matrix interactions. PMID:26682493

  3. High-Resolution Radar Scattering Characteristics of a Disturbed Sea Surface and Floating Debris

    DTIC Science & Technology

    1977-07-29

    theoretically and experimentally. Oil drums, logs, and aluminum-covered plastic gallon milk bottles were considered and measured. A comparison of the echoing...covered plastic bottle ,38 N R tEPO R1 8 131 0 DBSM L LJ v ’ da) B 6 GH1 0 DSM -- DBSM ib) 9.2 GHz Ils Fig. 29 - Vertically polarized return from wave...j2 ’ NRL Report 8131 (~High-Resolution Radar Scattering Characteristics of a Disturbed Sea Surface and Floating Debris B. L. LEWIS. J. P. HANSEN. 1

  4. Essential Characteristics of Plasma Antennas Driven by One-ended Surface Wave

    NASA Astrophysics Data System (ADS)

    Wang, Shiqing; Sun, Naifeng; Li, Jian; Xiang, Qian; Wei, Chaolei

    2010-04-01

    Based on the principle that one-ended electromagnetic surface wave can drive a plasma antenna, the relation between the effective length of an antenna column and the applied radio frequency (RF) power was studied both theoretically and experimentally. The density distribution along the antenna column as well as the electron temperature in different conditions were investigated. The characteristics of the reception of local frequency modulated (FM) electromagnetic wave by the plasma antenna were compared with that by a copper antenna with same dimensions. The results show that it is feasible to take plasma antennas as receiving ones.

  5. Dispersion states and surface characteristics of physically blended polyhedral oligomeric silsesquioxane/polymer hybrid nanocomposites

    NASA Astrophysics Data System (ADS)

    Misra, Rahul

    nanoscale tribomechanical characteristics in relation to the POSS structures. Chapter 5 probes the molecular miscibility, solution and solid-state chain dynamics in polystyrene solution blended with Oib- and Tsp-POSS based on classical thermodynamic principles. Chapter 6 extends the learnings from chapter 5 to utilize POSS as a dispersion aid to disperse TiO2 nanoparticles in polypropylene. Chapter 7 explores the surface properties of fluorinated and non-fluorinated POSS coated fabrics. Finally, chapter 8 explores a nature-inspired route to modify polymer surfaces utilizing hydrophobin proteins and their impact on surface morphology and nanotribological characteristics.

  6. New nanocomposite materials reinforced with cellulose whiskers in atactic polypropylene: effect of surface and dispersion characteristics.

    PubMed

    Ljungberg, N; Bonini, C; Bortolussi, F; Boisson, C; Heux, L; Cavaillé, J Y

    2005-01-01

    New nanocomposite films were prepared with atactic polypropylene as the matrix and either of three types of cellulose whiskers, with various surface and dispersion characteristics, as the reinforcing phase: aggregated without surface modification, aggregated and grafted with maleated polypropylene or individualized and finely dispersed with a surfactant. Films obtained by solvent casting from toluene were investigated by means of scanning electron microscopy, dynamic mechanical analysis, and tensile testing. In the linear region, the mechanical properties above the glass-rubber transition were found to be drastically enhanced for the nanocomposites as compared to the neat polypropylene matrix. These effects were ascribed to the formation of a rigid network with filler/filler interactions. In addition, interactions between the filler and the matrix as well as the dispersion quality were found to play a major role on the mechanical properties of the composites when investigation of the films was performed in the nonlinear region.

  7. Hydrodynamic characteristics of the surface-piercing propellers for the planing craft

    NASA Astrophysics Data System (ADS)

    Ghassemi, Hassan

    2009-12-01

    Demand for high-speed marine vehicles (HSMVs) is high among both commercial and naval users. It is the duty of the marine vessel’s designer to provide a hull and propulsion system that diminishes drag, improves propulsive efficiency, increases safety and improves maneuverability. From the propulsor side, surface piercing propellers (SPPs) should improve performance. Unlike immersed propellers, behavior of the SPP is affected by depth of immersion, Weber number and shaft inclination angle. This paper uses a practical numerical method to predict the hydrodynamic characteristics of an SPP. The critical advance velocity ratio is derived using the Weber number and pitch ratio in the transition mode, then the potential based boundary element method (BEM) is used on the engaged surfaces. Two models of three and six-bladed SPPs (SPP-1 and SPP-2) were selected and some results are shown.

  8. Surface characteristics and mechanical properties of high-strength steel wires in corrosive conditions

    NASA Astrophysics Data System (ADS)

    Xu, Yang; Li, Shunlong; Li, Hui; Yan, Weiming

    2013-04-01

    Cables are always a critical and vulnerable type of structural components in a long-span cable-stayed bridge in normal operation conditions. This paper presents the surface characteristics and mechanical performance of high-strength steel wires in simulated corrosive conditions. Four stress level (0MPa, 300MPa, 400MPa and 500MPa) steel wires were placed under nine different corrosive exposure periods based on the Salt Spray Test Standards ISO 9227:1990. The geometric feathers of the corroded steel wire surface were illustrated by using fractal dimension analysis. The mechanical performance index including yielding strength, ultimate strength and elastic modulus at different periods and stress levels were tested. The uniform and pitting corrosion depth prediction model, strength degradation prediction model as well as the relationship between strength degradation probability distribution and corrosion crack depth would be established in this study.

  9. Martian Buried Basins and Implications for Characteristics of the Burial Layer and Underlying Surface

    NASA Technical Reports Server (NTRS)

    Sarid, A. R.; Frey, H. V.; Roark, J. H.

    2003-01-01

    Deciphering the cratering record on Mars has been challenging because it may reflect the changes in both the population of impactors and in the resurfacing processes on Mars. However, it is possible to determine the breadth of impactors captured in the cratering record. Extensive areas of resurfacing are of particular interest because they likely contain material from various ages in Martian history. By deducing the impact populations in both surface and underlying layers of terrain, it is possible to determine the age of the layers and constrain theories on the development of the Martian surface. However, to do so requires a method of seeing impact features which are no longer visible. Topographic data of Mars, taken by the Mars Orbiter Laser Altimeter (MOLA), has revealed impact features buried by resurfacing processes. These features are often indistinguishable on Viking images of the Martian surface. In this study, gridded MOLA data was analyzed in order to locate buried impact features, also called buried basins, in Syria, Solis, and Sinai Planum just south of Valles Marineris. The population statistics of buried features can be compared to those of visible features in order to determine the age of the underlying material and characteristics of the surface cover. Specifically, if the buried population in the Hesperian terrain is similar to the population of visible features in the Noachian, it would suggest that the underlying terrain is Noachian in age. The buried craters can then be compared to visible Noachian craters to reveal the amount of deterioration of the buried features. These comparisons allow us to explore the morphology of the terrain in the Hesperian region to determine if topographic variations are due to differences in the thickness of the overlying material or are a characteristic of the underlying terrain.

  10. Large eddy simulations of surface roughness parameter sensitivity to canopy-structure characteristics

    NASA Astrophysics Data System (ADS)

    Maurer, K. D.; Bohrer, G.; Ivanov, V. Y.

    2014-11-01

    Surface roughness parameters are at the core of every model representation of the coupling and interactions between land-surface and atmosphere, and are used in every model of surface fluxes. However, most models assume these parameters to be a fixed property of plant functional type and do not vary them in response to spatial or temporal changes to canopy structure. In part, this is due to the difficulty of reducing the complexity of canopy structure and its spatiotemporal dynamic and heterogeneity to less than a handful of parameters describing its effects of atmosphere-surface interactions. In this study we use large-eddy simulations to explore, in silico, the effects of canopy structure characteristics on surface roughness parameters. We performed a virtual experiment to test the sensitivity of resolved surface roughness to four axes of canopy structure: (1) leaf area index, (2) the vertical profile of leaf density, (3) canopy height, and (4) canopy gap fraction. We found roughness parameters to be highly variable, but were able to find positive relationships between displacement height and maximum canopy height, aerodynamic canopy height and maximum canopy height and leaf area index, and eddy-penetration depth and gap fraction. We also found negative relationships between aerodynamic canopy height and gap fraction, and between eddy-penetration depth and maximum canopy height and leaf area index. Using a decade of wind and canopy structure observations in a site in Michigan, we tested the effectiveness of our model-resolved parameters in predicting the frictional velocity over heterogeneous and disturbed canopies. We compared it with three other semi-empirical models and with a decade of meteorological observations. We found that parameterizations with fixed representations of roughness performed relatively well. Nonetheless, some empirical approaches that incorporate seasonal and inter-annual changes to the canopy structure performed even better than models

  11. A HIGH TEMPERATURE TEST FACILITY FOR STUDYING ASH PARTICLE CHARACTERISTICS OF CANDLE FILTER DURING SURFACE REGENERATION

    SciTech Connect

    Kang, B.S-J.; Johnson, E.K.; Rincon, J.

    2002-09-19

    Hot gas particulate filtration is a basic component in advanced power generation systems such as Integrated Gasification Combined Cycle (IGCC) and Pressurized Fluidized Bed Combustion (PFBC). These systems require effective particulate removal to protect the downstream gas turbine and also to meet environmental emission requirements. The ceramic barrier filter is one of the options for hot gas filtration. Hot gases flow through ceramic candle filters leaving ash deposited on the outer surface of the filter. A process known as surface regeneration removes the deposited ash periodically by using a high pressure back pulse cleaning jet. After this cleaning process has been done there may be some residual ash on the filter surface. This residual ash may grow and this may lead to mechanical failure of the filter. A High Temperature Test Facility (HTTF) was built to investigate the ash characteristics during surface regeneration at high temperatures. The system is capable of conducting surface regeneration tests of a single candle filter at temperatures up to 1500 F. Details of the HTTF apparatus as well as some preliminary test results are presented in this paper. In order to obtain sequential digital images of ash particle distribution during the surface regeneration process, a high resolution, high speed image acquisition system was integrated into the HTTF system. The regeneration pressure and the transient pressure difference between the inside of the candle filter and the chamber during regeneration were measured using a high speed PC data acquisition system. The control variables for the high temperature regeneration tests were (1) face velocity, (2) pressure of the back pulse, and (3) cyclic ash built-up time.

  12. Ontogenetic variation in chemical and physical characteristics of adaxial apple leaf surfaces.

    PubMed

    Bringe, Katja; Schumacher, Christina F A; Schmitz-Eiberger, Michaela; Steiner, Ulrike; Oerke, Erich-Christian

    2006-01-01

    The reaction of plants to environmental factors often varies with developmental stage. It was hypothesized, that also the cuticle, the outer surface layer of plants is modified during ontogenesis. Apple plantlets, cv. Golden Delicious, were grown under controlled conditions avoiding biotic and abiotic stress factors. The cuticular wax surface of adaxial apple leaves was analyzed for its chemical composition as well as for its micromorphology and hydrophobicity just after unfolding of leaves ending in the seventh leaf insertion. The outer surface of apple leaves was formed by a thin amorphous layer of epicuticular waxes. Epidermal cells of young leaves exhibited a distinctive curvature of the periclinal cell walls resulting in an undulated surface of the cuticle including pronounced lamellae, with the highest density at the centre of cells. As epidermal cells expanded during ontogenesis, the upper surface showed only minor surface sculpturing and a decrease in lamellae. With increasing leaf age the hydrophobicity of adaxial leaf side decreased significantly indicated by a decrease in contact angle. Extracted from plants, the amount of apolar cuticular wax per area unit ranged from only 0.9 microgcm(-2) for the oldest studied leaf to 1.5 microgcm(-2) for the youngest studied leaf. Differences in the total amount of cuticular waxes per leaf were not significant for older leaves. For young leaves, triterpenes (ursolic acid and oleanolic acid), esters and alcohols were the main wax components. During ontogenesis, the proportion of triterpenes in total mass of apolar waxes decreased from 32% (leaf 1) to 13% (leaf 7); absolute amounts decreased by more than 50%. The proportion of wax alcohols and esters, and alkanes to a lesser degree, increased with leaf age, whereas the proportion of acids decreased. The epicuticular wax layer also contained alpha-tocopherol described for the first time to be present also in the epicuticular wax. The modifications in the chemical

  13. Plasma sheet at lunar distance - Characteristics and interactions with the lunar surface

    NASA Technical Reports Server (NTRS)

    Rich, F. J.; Reasoner, D. L.; Burke, W. J.

    1973-01-01

    The plasma sheet at lunar distance is investigated with the use of data from the charged particle lunar environment experiment (CPLEE), complemented with data from the Explorer 35/ARC magnetometer. It is shown that the presence of the lunar surface does not appreciably affect measurements of the plasma sheet characteristics by the lunar-based CPLEE instrument. In particular, the lunar surface generally does not shadow plasma sheet particles. This may be due to rapid random passage (greater than 40 km/sec) of magnetotail field lines with respect to the lunar surface or to diffusion of plasma sheet electrons into the flux tubes in contact with the lunar surface. The plasma sheet is generally observed as a rapid increase in observed particle fluxes and a simultaneous decrease in field strength. A statistical analysis of the CPLEE data shows that the plasma sheet in the midnight sector has a thickness of 5 R sub E plus or minus 2 R sub E. Geomagnetic activity reduces the probability of encounters between the moon and the plasma sheet.

  14. Surface characteristics and bioactivity of a novel natural HA/zircon nanocomposite coated on dental implants.

    PubMed

    Karamian, Ebrahim; Khandan, Amirsalar; Motamedi, Mahmood Reza Kalantar; Mirmohammadi, Hesam

    2014-01-01

    The surface characteristics of implant which influence the speed and strength of osseointegration include surface chemistry, crystal structure and crystallinity, roughness, strain hardening, and presence of impurities. The aim of this study was to evaluate the bioactivity and roughness of a novel natural hydroxyapatite/zircon (NHA/zircon) nanobiocomposite, coated on 316L stainless steel (SS) soaked in simulated body fluid (SBF). NHA/zircon nanobiocomposite was fabricated with 0 wt.%, 5 wt.%, 10 wt.%, and 15 wt.% of zircon in NHA using ball mill for 20 minutes. The composite mixture was coated on 316L SS using plasma spray method. The results are estimated using the scanning electron microscopy (SEM) observation to evaluate surface morphology, X-ray diffraction (XRD) to analyze phase composition, and transmission electron microscopy (TEM) technique to evaluate the shape and size of prepared NHA. Surfaces roughness tester was performed to characterize the coated nanocomposite samples. The maximum average R a (14.54 μm) was found in the NHA 10 wt.% of zircon coating. In addition, crystallinity (X c ) was measured by XRD data, which indicated the minimum value (X c = 41.1%) for the sample containing 10 wt.% of zircon. Maximum bioactivity occurred in the sample containing 10 wt.% of zircon, which was due to two reasons: first, the maximum roughness and, second, the minimum crystallinity of nanobiocomposite coating.

  15. Adsorption characteristics of N-nitrosodimethylamine from aqueous solution on surface-modified activated carbons.

    PubMed

    Dai, Xiaodong; Zou, Linda; Yan, Zifeng; Millikan, Mary

    2009-08-30

    This study investigated the removal of N-nitrosodimethylamine (NDMA) by an adsorption mechanism using commercially available activated carbons and surface-modified activated carbons. The effects of the modification on the properties of the activated carbon were studied by N(2) adsorption/desorption, Diffuse Reflectance Infrared Fourier Transmission (DRIFT) analysis and X-Ray Photoelectron Spectroscopy (XPS). Adsorption experiments revealed that the activated carbons demonstrated a greater capacity for NDMA adsorption capacity than can be achieved using zeolite. The equilibrium data was fitted to the Freundlich equation and it was found that the adsorption capacity was significantly influenced by the micropore size, relative pore volume and surface characteristics. Adsorption experiments were conducted using unmodified and modified activated carbons. The results indicated that the adsorption capacity of NDMA can be significantly improved by heat treatment and doping of TiO(2) particles. This was because the surface treatments yielded more hydrophobic sites and fewer oxygen-containing surface functional groups, and consequently an increased capacity for NDMA adsorption.

  16. Surface Characteristics and Bioactivity of a Novel Natural HA/Zircon Nanocomposite Coated on Dental Implants

    PubMed Central

    Karamian, Ebrahim; Khandan, Amirsalar

    2014-01-01

    The surface characteristics of implant which influence the speed and strength of osseointegration include surface chemistry, crystal structure and crystallinity, roughness, strain hardening, and presence of impurities. The aim of this study was to evaluate the bioactivity and roughness of a novel natural hydroxyapatite/zircon (NHA/zircon) nanobiocomposite, coated on 316L stainless steel (SS) soaked in simulated body fluid (SBF). NHA/zircon nanobiocomposite was fabricated with 0 wt.%, 5 wt.%, 10 wt.%, and 15 wt.% of zircon in NHA using ball mill for 20 minutes. The composite mixture was coated on 316L SS using plasma spray method. The results are estimated using the scanning electron microscopy (SEM) observation to evaluate surface morphology, X-ray diffraction (XRD) to analyze phase composition, and transmission electron microscopy (TEM) technique to evaluate the shape and size of prepared NHA. Surfaces roughness tester was performed to characterize the coated nanocomposite samples. The maximum average Ra (14.54 μm) was found in the NHA 10 wt.% of zircon coating. In addition, crystallinity (Xc) was measured by XRD data, which indicated the minimum value (Xc = 41.1%) for the sample containing 10 wt.% of zircon. Maximum bioactivity occurred in the sample containing 10 wt.% of zircon, which was due to two reasons: first, the maximum roughness and, second, the minimum crystallinity of nanobiocomposite coating. PMID:24822204

  17. Influence of surface defects in ZnO thin films on its biosensing response characteristic

    NASA Astrophysics Data System (ADS)

    Saha, Shibu; Gupta, Vinay

    2011-09-01

    Highly c-axis oriented zinc oxide (ZnO) thin films deposited by rf magnetron sputtering under varying processing pressure (20-50 mT) in a reactive gas mixture of argon and oxygen were studied for biosensing application. The as-deposited ZnO thin films were in a state of compressive stress having defects related to interstitial Zn and antisite oxygen. Glucose oxidase has been chosen as the model enzyme in the present study and was immobilized on the surface of ZnO thin films deposited on indium tin oxide coated Corning Glass substrate. The studies reveal a correlation between the biosensing characteristic and the presence of defects in the ZnO films. The ZnO films deposited under high pressure (50 mT) are found to be more sensitive for biosensing application due to availability of more surface area for effective immobilization of biomolecules and exhibits a suitable microenvironment with good electron transfer characteristic. The obtained results highlight the importance of desired microstate besides availability of suitable native defects in the ZnO thin film for exhibiting enhanced biosensing response.

  18. Application of inorganic-contaminated groundwater to surface soils and compliance with toxicity characteristic (TCLP) regulations

    SciTech Connect

    Bergren, C.L.; Flora, M.A. ); Jackson, J.L.; Hicks, E.M. )

    1991-01-01

    The Westinghouse Savannah River Company (WSRC) is currently implementing a Purged Water Management Program (PWMP) at the Savannah River Site (SRS) near Aiken, South Carolina. A variety of constituents and disposal strategies are being considered. Constituents investigated in the PWMP include radionuclides, organics, and inorganics (As, Ba, Cd, Cr, Pb, Hg, Se, and Ag). One practical disposal alternative is to discharge purged water (all constituents below regulatory levels) to the ground surface near the monitoring well that is being purged. The purpose of this investigation is to determine if long-term application of purged water that contains inorganic constituents (below regulatory levels) to surface soils will result in the accumulation of inorganics such that the soil becomes a hazardous waste according to the Toxicity Characteristic regulations (40 CFR Part 261.24). Two study soils were selected that encompass the range of soils found at the SRS: Lakeland and Orangeburg. Laboratory batch equilibrium studies indicate that the soils, although able to retain a large amount of inorganics, will not exceed Toxicity Characteristic concentrations when subjected to the TCLP. Field studies are underway to confirm this.

  19. Application of inorganic-contaminated groundwater to surface soils and compliance with toxicity characteristic (TCLP) regulations

    SciTech Connect

    Bergren, C.L.; Flora, M.A.; Jackson, J.L.; Hicks, E.M.

    1991-12-31

    The Westinghouse Savannah River Company (WSRC) is currently implementing a Purged Water Management Program (PWMP) at the Savannah River Site (SRS) near Aiken, South Carolina. A variety of constituents and disposal strategies are being considered. Constituents investigated in the PWMP include radionuclides, organics, and inorganics (As, Ba, Cd, Cr, Pb, Hg, Se, and Ag). One practical disposal alternative is to discharge purged water (all constituents below regulatory levels) to the ground surface near the monitoring well that is being purged. The purpose of this investigation is to determine if long-term application of purged water that contains inorganic constituents (below regulatory levels) to surface soils will result in the accumulation of inorganics such that the soil becomes a hazardous waste according to the Toxicity Characteristic regulations (40 CFR Part 261.24). Two study soils were selected that encompass the range of soils found at the SRS: Lakeland and Orangeburg. Laboratory batch equilibrium studies indicate that the soils, although able to retain a large amount of inorganics, will not exceed Toxicity Characteristic concentrations when subjected to the TCLP. Field studies are underway to confirm this.

  20. Relationships Between Abrasive Wear, Hardness, and Surface Grinding Characteristics of Titanium-Based Metal Matrix Composites

    SciTech Connect

    Blau, Peter Julian; Jolly, Brian C

    2009-01-01

    The objective of this work was to support the development of grinding models for titanium metal-matrix composites (MMCs) by investigating possible relationships between their indentation hardness, low-stress belt abrasion, high-stress belt abrasion, and the surface grinding characteristics. Three Ti-based particulate composites were tested and compared with the popular titanium alloy Ti-6Al-4V. The three composites were a Ti-6Al-4V-based MMC with 5% TiB{sub 2} particles, a Ti-6Al-4V MMC with 10% TiC particles, and a Ti-6Al-4V/Ti-7.5%W binary alloy matrix that contained 7.5% TiC particles. Two types of belt abrasion tests were used: (a) a modified ASTM G164 low-stress loop abrasion test, and (b) a higher-stress test developed to quantify the grindability of ceramics. Results were correlated with G-ratios (ratio of stock removed to abrasives consumed) obtained from an instrumented surface grinder. Brinell hardness correlated better with abrasion characteristics than microindentation or scratch hardness. Wear volumes from low-stress and high-stress abrasive belt tests were related by a second-degree polynomial. Grindability numbers correlated with hard particle content but were also matrix-dependent.

  1. Quantitative reconstruction of thermal and dynamic characteristics of lava flow from surface thermal measurements

    NASA Astrophysics Data System (ADS)

    Korotkii, Alexander; Kovtunov, Dmitry; Ismail-Zadeh, Alik; Tsepelev, Igor; Melnik, Oleg

    2016-06-01

    We study a model of lava flow to determine its thermal and dynamic characteristics from thermal measurements of the lava at its surface. Mathematically this problem is reduced to solving an inverse boundary problem. Namely, using known conditions at one part of the model boundary we determine the missing condition at the remaining part of the boundary. We develop a numerical approach to the mathematical problem in the case of steady-state flow. Assuming that the temperature and the heat flow are prescribed at the upper surface of the model domain, we determine the flow characteristics in the entire model domain using a variational (adjoint) method. We have performed computations of model examples and showed that in the case of smooth input data the lava temperature and the flow velocity can be reconstructed with a high accuracy. As expected, a noise imposed on the smooth input data results in a less accurate solution, but still acceptable below some noise level. Also we analyse the influence of optimization methods on the solution convergence rate. The proposed method for reconstruction of physical parameters of lava flows can also be applied to other problems in geophysical fluid flows.

  2. Seasonal variability of atmospheric surface layer characteristics and weather pattern in Qatar

    NASA Astrophysics Data System (ADS)

    Samanta, Dhrubajyoti; Cheng, Way Lee; Sadr, Reza

    2016-11-01

    Qatar's economy is based on oil and gas industry, which are mostly located in coastal regions. Therefore, better understanding of coastal weather, characteristics of surface layer and turbulence exchange processes is much needed. However, the turbulent atmospheric layer study in this region is severely limited. To support the broader aim and study long term precise wind information, a micro-meteorological field campaign has been carried out in a coastal location of north Qatar. The site is based on a 9 m tower, installed at Al Ghariya in the northern coast of Qatar, equipped with three sonic anemometers, temperature-humidity sensor, radiometer and a weather station. This study shows results based on the period August 2015 to July 2016. Various surface layer characteristics and modellings coefficients based on Monin Obukhov similarity theory is studied for the year and seasonal change is noted. Along with the seasonal variabilities of different weather parameters also observed. We hope this long term field observational study will be very much helpful for research community especially for modelers. In addition, two beach and shoreline monitoring cameras installed at the site could give first time information on waves and shoreline changes, and wind-wave interaction in Qatar. An Preliminary Analysis of Wind-Wave Interaction in Qatar in the Context of Changing Climate.

  3. Determination of thermal/dynamic characteristics of lava flow from surface thermal measurements

    NASA Astrophysics Data System (ADS)

    Ismail-Zadeh, Alik; Melnik, Oleg; Korotkii, Alexander; Tsepelev, Igor; Kovtunov, Dmitry

    2016-04-01

    Rapid development of ground based thermal cameras, drones and satellite data allows getting repeated thermal images of the surface of the lava flow. Available instrumentation allows getting a large amount of data during a single lava flow eruption. These data require development of appropriate quantitative techniques to link subsurface dynamics with observations. We present a new approach to assimilation of thermal measurements at lava's surface to the bottom of the lava flow to determine lava's thermal and dynamic characteristics. Mathematically this problem is reduced to solving an inverse boundary problem. Namely, using known conditions at one part of the model boundary we determine the missing condition at the remaining part of the boundary. Using an adjoint method we develop a numerical approach to the mathematical problem based on the determination of the missing boundary condition and lava flow characteristics. Numerical results show that in the case of smooth input data lava temperature and velocity can be determined with a high accuracy. A noise imposed on the smooth input data results in a less accurate solution, but still acceptable below some noise level. The proposed approach to assimilate measured data brings an opportunity to estimate thermal budget of the lava flow.

  4. Ligands Binding to Cell Surface Ganglioside GD2 Cause Src-Dependent Activation of N-Methyl-D-Aspartate Receptor Signaling and Changes in Cellular Morphology

    PubMed Central

    Gagnon, Martin; Saragovi, H. Uri

    2015-01-01

    Ganglioside GD2 is a plasma membrane glycosphinogolipid. In healthy adults it is expressed at low levels, but it is over-expressed in many cancers. For cancer therapy, GD2 is targeted with anti-GD2 monoclonal antibodies (mAbs), and one adverse side effect is severe visceral pain. Pain is not neuropathic, cannot be blocked with morphine, and stops on discontinuation of mAb therapy. Here, we provide evidence that ligand binding to cell surface GD2 induces rapid and transient activation of Src-family kinases, followed by Src-dependent phosphorylation of NMDA-receptor NR2B subunits selectively, activation of Ca++ fluxes, production of cAMP, and changes in cellular morphology. These GD2-ligand activated signals differ in kinetics and in pharmacology from activation of the same signals in the same cells by BDNF, the growth factor agonist of the TrkB receptor, suggesting biological specificity. Hence, cell surface GD2 regulates pathways that can be associated with neoplasia and with morphine-intractable pain; and this can explain why expression of GD2 correlates with these two pathologies. PMID:26252487

  5. Thermal surface characteristics of coal fires 1 results of in-situ measurements

    NASA Astrophysics Data System (ADS)

    Zhang, Jianzhong; Kuenzer, Claudia

    2007-12-01

    Natural underground coal fires are fires in coal seams occurring subsurface. The fires are ignited through a process named spontaneous combustion, which occurs based on a natural reaction but is usually triggered through human interaction. Coal mining activities expose coal to the air. This leads to the exothermal oxidation of the carbon in the coal with the air's oxygen to CO 2 and - under certain circumstances - to spontaneous combustion. Coal fires occur in many countries world wide - however, currently the Chinese coal mining industry faces the biggest problems with coal fires. Coal fires destroy the valuable resource coal and furthermore lead to many environmental degradation phenomena such as the deterioration of surrounding vegetation, land subsidence and the emission of toxic gasses (CO, N 2O). They additionally contribute to the emission of green house relevant gasses such as CO 2 and CH 4 to the atmosphere. In this paper we present thermal characteristics of coal fires as measured in-situ during a field campaign to the Wuda coal fire area in south-central Inner Mongolia, China. Thermal characteristics include temperature anomaly measurements at the surface, spatial surface temperature profiles of fire areas and unaffected background areas, diurnal temperature profiles, and temperature measurements inside of coal fire induced cracks in the overlying bedrock. For all the measurements the effects of uneven solar heating through influences of slope and aspect are considered. Our findings show that coal fires result in strong or subtle thermal surface anomalies. Especially the latter can easily be influenced by heating of the surrounding background material through solar influences. Temperature variation of background rocks with different albedo, slope, aspect or vegetation cover can substantially influence the detectability of thermal anomalies. In the worst case coal fire related thermal anomalies can be completely masked by solar patterns during the daytime

  6. The characteristics and interpretability of land surface change and implications for project design

    USGS Publications Warehouse

    Sohl, Terry L.; Gallant, Alisa L.; Loveland, Thomas R.

    2004-01-01

    The need for comprehensive, accurate information on land-cover change has never been greater. While remotely sensed imagery affords the opportunity to provide information on land-cover change over large geographic expanses at a relatively low cost, the characteristics of land-surface change bring into question the suitability of many commonly used methodologies. Algorithm-based methodologies to detect change generally cannot provide the same level of accuracy as the analyses done by human interpreters. Results from the Land Cover Trends project, a cooperative venture that includes the U.S. Geological Survey, Environmental Protection Agency, and National Aeronautics and Space Administration, have shown that land-cover conversion is a relatively rare event, occurs locally in small patches, varies geographically and temporally, and is spectrally ambiguous. Based on these characteristics of change and the type of information required, manual interpretation was selected as the primary means of detecting change in the Land Cover Trends project. Mixtures of algorithm-based detection and manual interpretation may often prove to be the most feasible and appropriate design for change-detection applications. Serious examination of the expected characteristics and measurability of change must be considered during the design and implementation phase of any change analysis project.

  7. Deformation characteristics of the near-surface layers of zirconia ceramics implanted with aluminum ions

    NASA Astrophysics Data System (ADS)

    Ghyngazov, S. A.; Vasiliev, I. P.; Frangulyan, T. S.; Chernyavski, A. V.

    2015-10-01

    The effect of ion treatment on the phase composition and mechanical properties of the near-surface layers of zirconium ceramic composition 97 ZrO2-3Y2O3 (mol%) was studied. Irradiation of the samples was carried out by accelerated ions of aluminum with using vacuum-arc source Mevva 5-Ru. Ion beam had the following parameters: the energy of the accelerated ions E = 78 keV, the pulse current density Ji = 4mA / cm2, current pulse duration equal τ = 250 mcs, pulse repetition frequency f = 5 Hz. Exposure doses (fluence) were 1016 и 1017 ion/cm2. The depth distribution implanted ions was studied by SIMS method. It is shown that the maximum projected range of the implanted ions is equal to 250 nm. Near-surface layers were investigated by X-ray diffraction (XRD) at fixed glancing incidence angle. It is shown that implantation of aluminum ions into the ceramics does not lead to a change in the phase composition of the near-surface layer. The influence of implanted ions on mechanical properties of ceramic near-surface layers was studied by the method of dynamic nanoindentation using small loads on the indenter P=300 mN. It is shown that in ion- implanted ceramic layer the processes of material recovery in the deformed region in the unloading mode proceeds with higher efficiency as compared with the initial material state. The deformation characteristics of samples before and after ion treatment have been determined from interpretation of the resulting P-h curves within the loading and unloading sections by the technique proposed by Oliver and Pharr. It was found that implantation of aluminum ions in the near-surface layer of zirconia ceramics increases nanohardness and reduces the Young's modulus.

  8. Nonlinear friction characteristics between silica surfaces in high pH solution.

    PubMed

    Taran, Elena; Kanda, Yoichi; Vakarelski, Ivan U; Higashitani, Ko

    2007-03-15

    Molecular-scale characteristics of friction forces between silica particles and silica wafers in aqueous solutions of the normal (pH 5.6) and high pH (pH 10.6) are investigated, using the lateral force measuring procedure of the atomic force microscope (AFM). Various significant differences of friction characteristics between solutions of normal and high pH's are found. In the case of solutions of normal pH, the friction force increases linearly with increasing loading force, as the Amonton's law for solid bodies indicates. However, in the case of high pH solutions, the increasing rate with the loading force is considerably reduced in the low loading region, but the value increases abruptly above a critical loading force to overcome the magnitude of friction force of normal pH above the region of very high loading. It is very interesting to know that this nonlinear force curve at high pH is independent of the atomic-scale roughness of surfaces, although the magnitude of friction is greatly influenced by the roughness in the case of normal pH. The reason why the friction at high pH is independent of the surface roughness is postulated to be due to the hairy-like layer formed on the silica surface. The existence of hairy-like layers at high pH is proven directly by the dynamic method of normal force measurements with AFM and the thickness is estimated to be at least ca. 1.3 nm.

  9. The stress relaxation characteristics of composite matrices etched to produce nanoscale surface features

    PubMed Central

    Mirani, Rahul D.; Pratt, Jonathan; Iyer, Pooja; Madihally, Sundararajan V.

    2010-01-01

    Many synthetic and xenogenic natural matrices have been explored in tissue regeneration, however, they lack either mechanical strength or cell colonization characteristics found in natural tissue. Moreover natural matrices such as small intestinal submucosa (SIS) lack sample to sample homogeneity, leading to unpredictable clinical outcomes. This work explored a novel fabrication technique by blending together the useful characteristics of synthetic and natural polymers to form a composite structure by using a NaOH etching process that produces nanoscale surface features. The composite scaffold was formed by sandwiching a thin layer of PLGA between porous layers of gelatin–chitosan. The etching process increased the surface roughness of PLGA membrane, allowing easy spreading of the hydrophilic gelatin–chitosan solution on its hydrophobic surface and reducing the scaffold thickness by nearly 50% than otherwise. The viscoelastic properties of the scaffold, an area of mechanical analysis which remains largely unexplored in tissue regeneration was assessed. Stress relaxation experiments of the “ramp and hold” type performed at variable ranges of temperature (25 °C and 37 °C), loading rates (3.125% s−1 and 12.5% s−1) and relaxation times (60 s, 100 s and 200 s) found stress relaxation to be sensitive to temperature and the loading rate but less dependent on the relaxation time. Stress relaxation behavior of the composite matrix was compared with SIS structures at 25 °C (hydrated), 3.125% s−1 loading rate and 100 s relaxation time which showed that the synthetic matrix was found to be strain softening as compared to the strain hardening behavior exhibited by SIS. Popularly used quasi-linear viscoelastic (QLV) model to describe biomechanics of soft tissues was utilized. The QLV model predicted the loading behavior with an average error of 3%. The parameters of the QLV model predicted using nonlinear regression analysis appear to be in concurrence with soft

  10. Impact of catchment geophysical characteristics and climate on the regional variability of dissolved organic carbon (DOC) in surface water.

    PubMed

    Cool, Geneviève; Lebel, Alexandre; Sadiq, Rehan; Rodriguez, Manuel J

    2014-08-15

    Dissolved organic carbon (DOC) is a recognized indicator of natural organic matter (NOM) in surface waters. The aim of this paper is twofold: to evaluate the impact of geophysical characteristics, climate and ecological zones on DOC concentrations in surface waters and, to develop a statistical model to estimate the regional variability of these concentrations. In this study, multilevel statistical analysis was used to achieve three specific objectives: (1) evaluate the influence of climate and geophysical characteristics on DOC concentrations in surface waters; (2) compare the influence of geophysical characteristics and ecological zones on DOC concentrations in surface waters; and (3) develop a model to estimate the most accurate DOC concentrations in surface waters. The case study involved 115 catchments from surface waters in the Province of Quebec, Canada. Results showed that mean temperatures recorded 60 days prior to sampling, total precipitation 10 days prior to sampling and percentages of wetlands, coniferous forests and mixed forests have a significant positive influence on DOC concentrations in surface waters. The catchment mean slope had a significant negative influence on DOC concentrations in surface waters. Water type (lake or river) and deciduous forest variables were not significant. The ecological zones had a significant influence on DOC concentrations. However, geophysical characteristics (wetlands, forests and slope) estimated DOC concentrations more accurately. A model describing the variability of DOC concentrations was developed and can be used, in future research, for estimating DBPs in drinking water as well evaluating the impact of climate change on the quality of surface waters and drinking water.

  11. The role of angiogenesis in implant dentistry part I: Review of titanium alloys, surface characteristics and treatments

    PubMed Central

    Asatourian, Armen; Garcia-Godoy, Franklin; Sheibani, Nader

    2016-01-01

    Background Angiogenesis plays an important role in osseointegration process by contributing to inflammatory and regenerative phases of surrounding alveolar bone. The present review evaluated the effect of titanium alloys and their surface characteristics including: surface topography (macro, micro, and nano), surface wettability/energy, surface hydrophilicity or hydrophobicity, surface charge, and surface treatments of dental implants on angiogenesis events, which occur during osseointegration period. Material and Methods An electronic search was performed in PubMed, MEDLINE, and EMBASE databases via OVID using the keywords mentioned in the PubMed and MeSH headings regarding the role of angiogenesis in implant dentistry from January 2000-April 2014. Results Of the 2,691 articles identified in our initial search results, only 30 met the inclusion criteria set for this review. The hydrophilicity and topography of dental implants are the most important and effective surface characteristics in angiogenesis and osteogenesis processes. The surface treatments or modifications of dental implants are mainly directed through the enhancement of biological activity and functionalization in order to promote osteogenesis and angiogenesis, and accelerate the osseointegration procedure. Conclusions Angiogenesis is of great importance in implant dentistry in a manner that most of the surface characteristics and treatments of dental implants are directed toward creating a more pro-angiogenic surface on dental implants. A number of studies discussed the effect of titanium alloys, dental implant surface characteristic and treatments on agiogenesis process. However, clinical trials and in-vivo studies delineating the mechanisms of dental implants, and their surface characteristics or treatments, action in angiogenesis processes are lagging. Key words:Angiogenesis, dental implant, osseointergration. PMID:27031073

  12. Characteristics of postural muscle activation patterns induced by unexpected surface perturbations in elite ski jumpers.

    PubMed

    Mani, Hiroki; Izumi, Tatsuya; Konishi, Tomoya; Samukawa, Mina; Yamamoto, Keizo; Watanabe, Kazuhiko; Asaka, Tadayoshi

    2014-06-01

    [Purpose] This study investigated the characteristics of postural control following postural disturbance in elite athletes. [Subjects] Ten elite ski jumpers and ten control subjects participated in this study. [Methods] Subjects were required to maintain balance without stepping following unexpected horizontal surface perturbation in a forward or backward direction. [Results] A lower and reproducible peak magnitude of the center of mass velocity was shown in the athlete group compared to the control group. Cross-correlation analyses showed longer time lags at the moment of peak correlation coefficient between trunk flexor and extensor muscle activities, and shorter time lags and higher correlations between ankle flexor and extensor muscle activities were shown in the athlete group than in the control group. [Conclusion] The elite ski jumpers showed superior balance performance following surface perturbations, more reciprocal patterns in agonist-antagonist pairs of proximal postural muscles, and more co-contraction patterns in distal postural muscles during automatic postural responses than control individuals. This strategy may be useful in sports requiring effective balance recovery in environments with a dynamically changing surface, as well as in rehabilitation.

  13. Do skeletal cephalometric characteristics correlate with condylar volume, surface and shape? A 3D analysis

    PubMed Central

    2012-01-01

    Objective The purpose of this study was to determine the condylar volume in subjects with different mandibular divergence and skeletal class using cone-beam computed tomography (CBCT) and analysis software. Materials and methods For 94 patients (46 females and 48 males; mean age 24.3 ± 6.5 years), resultant rendering reconstructions of the left and right temporal mandibular joints (TMJs) were obtained. Subjects were then classified on the base of ANB angle the GoGn-SN angle in three classes (I, II, III) . The data of the different classes were compared. Results No significant difference was observed in the whole sample between the right and the left sides in condylar volume. The analysis of mean volume among low, normal and high mandibular plane angles revealed a significantly higher volume and surface in low angle subjects (p < 0.01) compared to the other groups. Class III subjects also tended to show a higher condylar volume and surface than class I and class II subjects, although the difference was not significant. Conclusions Higher condylar volume was a common characteristic of low angle subjects compared to normal and high mandibular plane angle subjects. Skeletal class also appears to be associated to condylar volume and surface. PMID:22587445

  14. Trends of urban surface temperature and heat island characteristics in the Mediterranean

    NASA Astrophysics Data System (ADS)

    Benas, Nikolaos; Chrysoulakis, Nektarios; Cartalis, Constantinos

    2016-09-01

    Urban air temperature studies usually focus on the urban canopy heat island phenomenon, whereby the city center experiences higher near surface air temperatures compared to its surrounding non-urban areas. The Land Surface Temperature (LST) is used instead of urban air temperature to identify the Surface Urban Heat Island (SUHI). In this study, the nighttime LST and SUHI characteristics and trends in the seventeen largest Mediterranean cities were investigated, by analyzing satellite observations for the period 2001-2012. SUHI averages and trends were based on an innovative approach of comparing urban pixels to randomly selected non-urban pixels, which carries the potential to better standardize satellite-derived SUHI estimations. A positive trend for both LST and SUHI for the majority of the examined cities was documented. Furthermore, a 0.1 °C decade-1 increase in urban LST corresponded to an increase in SUHI by about 0.04 °C decade-1. A longitudinal differentiation was found in the urban LST trends, with higher positive values appearing in the eastern Mediterranean. Examination of urban infrastructure and development factors during the same period revealed correlations with SUHI trends, which can be used to explain differences among cities. However, the majority of the cities examined show considerably increased trends in terms of the enhancement of SUHI. These findings are considered important so as to promote sustainable urbanization, as well as to support the development of heat island adaptation and mitigation plans in the Mediterranean.

  15. Calculation of the longitudinal aerodynamic characteristics of upper-surface-blown wing-flap configurations

    NASA Technical Reports Server (NTRS)

    Mendenhall, M. R.; Spangler, S. B.

    1978-01-01

    An engineering method for predicting the longitudinal aerodynamic characteristics of wing-flap configurations with upper surface blowing (USB) was developed. Potential flow models were incorporated into the prediction method: a wing and flap lifting surface model and a jet wake model. The wing-flap model used a vortex-lattice to represent the wing and flaps. The wing had an arbitrary planform and camber and twist, and the flap system was made up of a Coanda flap and other flap segments of arbitrary size. The jet wake model consisted of a series of closely spaced rectangular vortex rings. The wake was positioned such that it was tangent to the upper surface of the wing and flap between the exhaust nozzle and the flap trailing edge. It was specified such that the mass, momentum, and spreading rates were similar to actual USB jet wakes. Comparisons of measured and predicted pressure distributions, span load distributions, and total lift and pitching-moment coefficients on swept and unswept USB configurations are included. A wide range of thrust coefficients and flap deflection angles were considered at angles of attack up to the onset of stall.

  16. Dynamic wetting and spreading characteristics of a liquid droplet impinging on hydrophobic textured surfaces.

    PubMed

    Lee, Jae Bong; Lee, Seong Hyuk

    2011-06-07

    We report on the wetting dynamics of a 4.3 μL deionized (DI) water droplet impinging on microtextured aluminum (Al 6061) surfaces, including microhole arrays (hole diameter 125 μm and hole depth 125 μm) fabricated using a conventional microcomputer numerically controlled (μ-CNC) milling machine. This study examines the influence of the texture area fraction ϕ(s) and drop impact velocity on the spreading characteristics from the measurement of the apparent equilibrium contact angle, dynamic contact angle, and maximum spreading diameter. We found that for textured surfaces the measured apparent contact angle (CA) takes on values of up to 125.83°, compared to a CA of approximately 80.59° for a nontextured bare surface, and that the spreading factor decreases with the increased texture area fraction because of increased hydrophobicity, partial penetration of the liquid, and viscous dissipation. In particular, on the basis of the model of Ukiwe and Kwok (Ukiwe, C.; Kwok, D. Y. Langmuir 2005, 21, 666), we suggest a modified equation for predicting the maximum spreading factor by considering various texturing effects and wetting states. Compared with predictions by using earlier published models, the present model shows better agreement with experimental measurements of the maximum spreading factor.

  17. Spatial variation in spoil and vegetative characteristics of pastures on reclaimed surface mined land

    SciTech Connect

    Teutsch, C.D.; Collins, M.; Ditsch, D.C.

    1999-07-01

    Kentucky has large areas of reclaimed surface mined land that could provide grazing for livestock. Research is needed to determine optimal stocking densities and to evaluate the sustainability of such grazing systems for this region. A long-term grazing study was initiated in 1997 on 151 ha of reclaimed land near Chavies, KY to determine spatial and temporal variation with stocking densities of 0, 0.28, 0.42, or 0.83 beef cow-calf units/ha. Global Positioning System and GIS technologies were used to establish pasture boundaries, locate permanent sampling markers at a density of 1 per 0.4 ha, and interpolate maps of physical, spoil, and vegetable pasture characteristics. Herbage and spoil samples were collected around the permanent markers in May of 1997. Stepwise regression was used to determine factors affecting the vegetative characteristics of the sites. Biomass density ranged from 0 to 2500 kg/ha with a mean of 570 kg/ha. Factors affecting biomass included legume and weed proportions in the sward, grazing activity, soil potassium, elevation, and potential acidity, cumulatively accounting for 32% of the variation. Ground cover ranged from 10 to 100% with an average of 74%. Soil pH, potassium, and grass in the sward accounted for 14% of the variation in ground cover. Legumes made up 0 to 61% of the sward with a mean of 13% over the pasture area. Variables affecting the amount of legume in the sward included biomass density, slope, elevation, pH, and stocking density, together accounting for 21% of the variation. Spatial variation in the physical, spoil, and vegetative characteristics of the pastures was large. Overall, regression accounted for a limited amount of the variation in the vegetative characteristics of the site indicating that other important variables exist.

  18. Lipopeptide-based micellar and liposomal carriers: Influence of surface charge and particle size on cellular uptake into blood brain barrier cells.

    PubMed

    Sydow, Karl; Nikolenko, Heike; Lorenz, Dorothea; Müller, Rainer H; Dathe, Margitta

    2016-12-01

    Lipopeptide-based micelles and liposomes were found to differ in cell recognition and uptake mode into blood brain barrier (BBB) endothelial cells. Here we analyse the role of size and surface charge of micelles and liposomes composed of different lipopeptide sequences with respect to uptake into human brain capillary (HBMEC) and aortic (HAoEC) endothelial cells. Comparable to the dipalmitoylated apolipoprotein E-derived P2A2, lipopeptides of cationic poly-arginine (P2Rn), poly-lysine (P2Kn) and an anionic glutamic-acid sequence (P2En) self assemble into micelles (12-14nm in diameter) with high surface charge density, and bind to small (SUVs, about 24nm in diameter) and large (LUV, about 100nm in diameter) liposomes at variable lipid to peptide ratios. The interaction pattern of the resulting particles with endothelial cells is highly variable as revealed by confocal laser scanning microscopic (CLSM) and fluorescence assisted cell sorting (FACS) studies. Micelles and SUVs with high P2A2 density are efficiently and selectively internalized into HBMEC. P2Kn micelles strongly accumulate in both the cytosol and at the cell membrane, while the interaction of liposomes tagged with a low amount of P2A2 and P2Kn with the cells was reduced. Anionic micelles seem to dissociate in the presence of cells and P2En molecules incorporate into the cellular membrane whereas the negatively charged liposomes hardly interact with cells. Surprisingly, all poly-R-based particles show high selectivity for HBMEC compared to HAoEC, independent of particle size and peptide surface density. The P2Rn-mediated internalization is highly efficient and partially clathrin-dependent. The oligo-R lipopeptide is considered to be most promising to selectively transport different drug carriers into the blood brain barrier.

  19. Preliminary Correlation of the Effects of Beveled Trailing Edges on the Hinge-Moment Characteristics of Control Surfaces

    NASA Technical Reports Server (NTRS)

    Purser, Paul E.; Gillis, Clarence L.

    1943-01-01

    A study of available data from various tests of beveled control surfaces has been made in an attempt to develop a rational method for predicting the effects of beveled trailing edges on the hinge-moment characteristics of control surfaces in both two- and three-dimensional flow. The results of the study indicated that the change in the included angle at the control-surface trailing edge formed a convenient basis on which a correlation could be made of the effects of various profile modifications on hinge-moment characteristics. It is believed that the formulas developed will allow reasonably accurate predictions of the hinge-moment characteristics of sealed beveled control surfaces if the characteristics of the original control surfaces are known. The presence of a gap at the control-surface hinge increased the effect of beveled trailing edges on the hinge-moment characteristics at small control-surface deflections but the available data were insufficient to allow as complete a correlation as was possible for sealed controls.

  20. Heat transfer characteristics of laminar methane/air flame impinging normal to a cylindrical surface

    SciTech Connect

    Chander, Subhash; Ray, Anjan

    2007-11-15

    An experimental study has been conducted to determine the heat transfer characteristics of methane/air laminar flames impinging normal to a cylindrical surface. Effects of variations in the values of Reynolds number (Re = 600-1300), equivalence ratio ({phi} = 0.8-1.3), dimensionless separation distance (H/d = 1-5), and burner diameter to cylinder diameter ratio (d/D = 0.0538-0.1076) have been investigated. Three important configurations, viz., flame inner reaction zone far away, just touching and intercepted by the impingement surface, were examined in detail. High stagnation point heat fluxes were obtained when tip of the flame inner reaction zone just touched the target surface. Stagnation point heat fluxes were either zero or negative when the inner reaction zone was intercepted by the impingement surface. An off-stagnation peak in heat flux was obtained at moderate separation distances above the flame tip. Both stagnation point and peak heat fluxes increased with Re when the inner reaction zone length was less than the separation distance. Heat fluxes in the wall-jet region were high at high Re. Maximum heat fluxes were obtained for initially fuel-rich mixture conditions due to entrainment of the surrounding air. Smaller burner diameters produced high heat flux at the stagnation region for fixed Reynolds number and opposite trends were seen in the wall-jet region. A secondary rise in stagnation point heat flux was obtained at larger separation distances. This secondary rise in heat flux was quite significant for larger burner diameters and at low flow rates. Correlations were developed for stagnation point heat flux. Results were also compared with flat plate under identical operating conditions. (author)

  1. Different bed surface and flow resistance characteristics for gravel and sand bed

    NASA Astrophysics Data System (ADS)

    Fan, N.; Yang, K.; Nie, R.; Liu, X.

    2014-12-01

    Bed forms affect both bed load transport and flow resistance strongly and change their shapes and sizes depending on underlying grain size distribution and shear stress. A series of flume experiments were conducted at the Saint Anthony Falls Laboratory to study the effect of bed form dynamics on flow turbulence and sediment transport with both gravel and sand as bed material and different flow conditions. From the experimental data, the spectrum of bed elevation time series, the PDFs of bed elevation increments and the flow resistance characteristics are all analyzed. The wavelet-based spectral analysis shows that the slopes of the elevation spectrums are -2 and -3 for gravel and sand bed surfaces, respectively. The slope -3 indicates that the surface is self-similar, in another words, the ratios of bed form heights and lengths for different bed forms are the same; however, the slope of -2 indicates that the surface is self-affine, and in such case (-2) the ratios of bed form heights and lengths for different bed forms are not correlated at all. We interpret that the relative size of grain and boundary layer affects the bed form characteristics significantly, e.g., grain size of sand is of the same scale as the thickness of boundary layer, but both are much smaller than the grain size of gravel. Our results suggest that the PDFs of bed elevation increments for both gravel and sand beds can be fitted well with two-sided asymmetric exponential function. Furthermore, we show that the flow resistance (Darcy-Weisbach coefficients f) are much higher for sand bed than gravel bed, and the former is contributed by form drags, which is much larger than grain drags. For gravel bed, f and the skewness of bed elevation increments increases with flow discharge whereas for the sand bed, both f and the skewness of bed elevation increments decreases which corresponds to the transition in hydraulic conditions for dune to dynamic flat surface in our experiments. The analysis

  2. Observations of Brine Pool Surface Characteristics and Internal Structure Through Remote Acoustic and Structured Light Imaging

    NASA Astrophysics Data System (ADS)

    Smart, C.; Roman, C.; Michel, A.; Wankel, S. D.

    2015-12-01

    Observations and analysis of the surface characteristics and internal structure of deep-sea brine pools are currently limited to discrete in-situ observations. Complementary acoustic and structured light imaging sensors mounted on a remotely operated vehicle (ROV) have demonstrated the ability systematically detect variations in surface characteristics of a brine pool, reveal internal stratification and detect areas of active hydrocarbon activity. The presented visual and acoustic sensors combined with a stereo camera pair are mounted on the 4000m rated ROV Hercules (Ocean Exploration Trust). These three independent sensors operate simultaneously from a typical 3m altitude resulting in visual and bathymetric maps with sub-centimeter resolution. Applying this imaging technology to 2014 and 2015 brine pool surveys in the Gulf of Mexico revealed acoustic and visual anomalies due to the density changes inherent in the brine. Such distinct changes in acoustic impedance allowed the high frequency 1350KHz multibeam sonar to detect multiple interfaces. For instance, distinct acoustic reflections were observed at 3m and 5.5m below the vehicle. Subsequent verification using a CDT and lead line indicated the acoustic return from the brine surface was the signal at 3m, while a thicker muddy and more saline interface occurred at 5.5m, the bottom of the brine pool was not located but is assumed to be deeper than 15m. The multibeam is also capable of remotely detecting emitted gas bubbles within the brine pool, indicative of active hydrocarbon seeps. Bubbles associated with these seeps were not consistently visible above the brine while using the HD camera on the ROV. Additionally, while imaging the surface of brine pool the structured light sheet laser became diffuse, refracting across the main interface. Analysis of this refraction combined with varying acoustic returns allow for systematic and remote detection of the density, stratification and activity levels within and

  3. The role of current characteristics of the arc evaporator in formation of the surface metal-coating composite

    NASA Astrophysics Data System (ADS)

    Plikhunov, V. V.; Petrov, L. M.; Grigorovich, K. V.

    2016-07-01

    The influence of current characteristics of the vacuum arc evaporator on the interaction process of plasma streams with the surface under treatment during generation of the physicochemical properties of the formed metal-coating composite is considered. It is shown that the interaction of plasma streams with the processed surface provides surface heating, defects elimination, change in energy properties, and mass transfer of plasma stream elements activating surface diffusion processes whose intensity is evaluated by the arc current magnitude and location of the processed surface relative to the cathode axis.

  4. Influence of carvacrol and thymol on the physiological attributes, enterotoxin production and surface characteristics of Staphylococcus aureus strains isolated from foods

    PubMed Central

    Souza, E.L.; Oliveira, C.E.V.; Stamford, T.L.M.; Conceição, M.L.; Neto, N.J. Gomes

    2013-01-01

    This study evaluated the influence of the phenolic compounds carvacrol (CAR) and thymol (THY) on some physiological characteristics and on the modulation of the secretion of some staphylococcal virulence factors, that is, coagulase and enterotoxin. This study also investigated possible mechanisms for the establishment of the anti-staphylococcal activity of these compounds. Sublethal concentrations (0.3 and 0.15 μL/mL) of CAR and THY inhibited the activity of the enzymes coagulase and lipase and led to a decrease in salt tolerance. At the tested sublethal concentrations, both CAR and THY led to a total suppression of enterotoxin production. The loss of a 260-nm-absorbing material and an efflux of potassium ions occurred immediately after the addition of CAR and THY at 0.6 and 1.2 μL/mL and increased up to 120 min of exposure. Electron microscopy of cells exposed to CAR and THY (0.6 μL/mL) revealed that individual cells appeared to be deformed, with projections of cellular material. The observations of leakage of cellular material and an altered cell surface suggest that gross damage to a cell’s cytoplasmic membrane, which results in a disruption in protein secretion, could be responsible for the anti-staphylococcal properties of CAR and THY. PMID:24159280

  5. Propagation characteristics of surface plasmon polariton modes in graphene layer with nonlinear magnetic cladding

    NASA Astrophysics Data System (ADS)

    Bhagyaraj, C.; Ajith, R.; Vincent, Mathew

    2017-03-01

    We study the dispersion characteristics of surface plasmon polariton modes guided through a graphene monolayer bounded with a nonlinear magnetic cladding and linear substrate. Nonlinear cladding with permeability μ ={μ }{{l}}+{μ }{{nl}}| {\\boldsymbol{H}}{| }2 provides an extra hand for controlling guided mode behavior externally. The presence of graphene layer enhances nonlinearity in the waveguide configuration thereby changing position of the self-focused peak of field components in the nonlinear medium. Also the propagation length of the fundamental mode strongly depends on the chemical potential of graphene layer. An appreciable increase in propagation length with increase in input power is observed. Phase constant and propagation length of the fundamental mode are calculated as a function of input mode power and graphene layer chemical potential over midinfrared frequencies.

  6. Effect of diffusion and surface recombination on the frequency-dependent characteristics of an OPFET

    NASA Astrophysics Data System (ADS)

    Singh, Vinaya K.

    1993-02-01

    Analytical studies have been made on the effect of diffusion and surface recombination on the frequency dependent characteristics of an ion-implanted GaAs optical field effect transistor. Modulated optical generation and voltage dependent depletion layer width in the active region have been considered whereas photovoltaic effect is ignored in this analysis. Result shows that drain-source current decreases with the increases of modulated signal frequency but diffusion effect increases the modulating frequency range from c.m. to m.m. wavelength. Moreover, I- V changes significantly with the trap center density only when Nr >= 1023/m2 with diffusion effect and >= 1020/m2 without diffusion effect at a particular dimension of the device. This model may be very much useful to measure the sensitivity of the device in terms of trap center density and modulating frequency.

  7. Decay Characteristics of Surface Mounds with Contrasting Interlayer Mass Transport Channels

    SciTech Connect

    Li, Maozhi; Wendelken, J. F.; Liu, Bang-Gui; Wang, E. G.; Zhang, Zhenyu

    2001-03-12

    The decay characteristics of three-dimensional (3D) islands formed on surfaces are investigated theoretically considering two types of interlayer mass transport mechanisms. If an adatom on a given layer can easily descend from any site along the periphery of the layer, an optimal island slope and a constant terrace width will be selected during the decay. In contrast, if the adatom can descend primarily through selective (such as kinked) sites, the decay will be accompanied by a gradual increase in the island slope. These generic conclusions provide the basis for a microscopic understanding of the decay of nanostructures in fcc(111) and fcc(100) metal homoepitaxy and are applicable to other systems as well.

  8. Decay characteristics of surface mounds with contrasting interlayer mass transport channels.

    PubMed

    Li, M; Wendelken, J F; Liu, B G; Wang, E G; Zhang, Z

    2001-03-12

    The decay characteristics of three-dimensional (3D) islands formed on surfaces are investigated theoretically considering two types of interlayer mass transport mechanisms. If an adatom on a given layer can easily descend from any site along the periphery of the layer, an optimal island slope and a constant terrace width will be selected during the decay. In contrast, if the adatom can descend primarily through selective (such as kinked) sites, the decay will be accompanied by a gradual increase in the island slope. These generic conclusions provide the basis for a microscopic understanding of the decay of nanostructures in fcc(111) and fcc(100) metal homoepitaxy and are applicable to other systems as well.

  9. Distribution and characteristics of organic micropollutants in surface sediments from Bohai Sea.

    PubMed

    Liu, Wen Xin; Chen, Jiang Lin; Lin, Xiu Mei; Tao, Shu

    2006-03-01

    Spatial distribution and compositional characteristics of PAHs, DDTs and PCBs in surface sediments from Bohai Sea were investigated. Proportion of LMW PAHs at Jinzhou Bay was significant, due probably to the petrogenic sources from neighboring oil wells and plants, while HMW PAHs were dominant in the other sea areas, inferred pyrogenic origins mainly from coal or petroleum combustion. The average ERL quotient for the PAH species in Qinhuangdao and Liaodong Bay indicated relatively stronger potential ecological risk. The concentration ratios of DDT to metabolites (DDD + DDE) exceeded 1.0 in the coastal areas of Qinhuangdao, Liaodong Bay and Bohai Bay, demonstrated some recent inputs of DDT nearby, and DDD as the major degradation product. The concentrations of PCBs were generally low, however, the contents of DDTs were greater than the ERL guidelines in the coastal areas of Qinhuangdao, Liaodong Bay and Bohai Bay, and suggested the potential ecological risk.

  10. Improvement in characteristics of natural rubber nanocomposite by surface modification of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Takeuchi, Kenji; Noguchi, Toru; Ueki, Hiroyuki; Niihara, Ken-ichi; Sugiura, Tomoyoshi; Inukai, Shigeki; Fujishige, Masatsugu

    2015-05-01

    We aim to develop high-level applications of NR through the innovative use of multi-walled carbon nanotubes (MWCNTs) to improve reinforcing performance and thermal resistance. In this study, we examined the structures and characteristics of composite materials in which NR was the matrix and MWCNTs were the fillers. We studied the properties of composites containing surface-activated MWCNTs with three different diameters. The results show that the reinforcing performance improves as MWCNT diameter decreases, while thermal resistance improves as we decrease the heat-treatment temperature. The latter occurs because adherence between MWCNTs and NR becomes stronger at lower heat-treatment temperatures. We also found that for practical applications, we need to control active sites on MWCNTs to balance adhesion against thermal resistance.

  11. Sensitivity of surface characteristics on the simulation of wind-blown-dust source in North America

    NASA Astrophysics Data System (ADS)

    Park, S. H.; Gong, S. L.; Gong, W.; Makar, P. A.; Moran, M. D.; Stroud, C. A.; Zhang, J.

    Recently, a wind-blown-dust-emission module has been built based on a state-of-the-art wind erosion theory and evaluated in a regional air-quality model to simulate a North American dust storm episode in April 2001 (see Park, S.H., Gong, S.L., Zhao, T.L., Vet, R.J., Bouchet, V.S., Gong, W., Makar, P.A., Moran, M.D., Stroud, C., Zhang, J. 2007. Simulation of entrainment and transport of dust particles within North America in April 2001 ("Red Dust episode"). J. Geophys. Res. 112, D20209, doi:10.1029/2007JD008443). A satisfactorily detailed assessment of that module, however, was not possible because of a lack of information on some module inputs, especially soil moisture content. In this paper, the wind-blown-dust emission was evaluated for two additional dust storms using improved soil moisture inputs. The surface characteristics of the wind-blown-dust source areas in southwestern North America were also investigated, focusing on their implications for wind-blown-dust emissions. The improved soil moisture inputs enabled the sensitivity of other important surface characteristics, the soil grain size distribution and the land-cover, to dust emission to be investigated with more confidence. Simulations of the two 2003 dust storm episodes suggested that wind-blown-dust emissions from the desert areas in southwestern North America are dominated by emissions from dry playas covered with accumulated alluvial deposits whose particle size is much smaller than usual desert sands. As well, the source areas in the northwestern Texas region were indicated to be not desert but rather agricultural lands that were "activated" as a wind-blown-dust sources after harvest. This finding calls for revisions to the current wind-blown-dust-emission module, in which "desert" is designated to be the only land-cover category that can emit wind-blown dust.

  12. Radiation characteristics of input power from surface wave sustained plasma antenna

    NASA Astrophysics Data System (ADS)

    Naito, T.; Yamaura, S.; Fukuma, Y.; Sakai, O.

    2016-09-01

    This paper reports radiation characteristics of input power from a surface wave sustained plasma antenna investigated theoretically and experimentally, especially focusing on the power consumption balance between the plasma generation and the radiation. The plasma antenna is a dielectric tube filled with argon and small amount of mercury, and the structure is a basic quarter wavelength monopole antenna at 2.45 GHz. Microwave power at 2.45 GHz is supplied to the plasma antenna. The input power is partially consumed to sustain the plasma, and the remaining part is radiated as a signal. The relationship between the antenna gain and the input power is obtained by an analytical derivation and numerical simulations. As a result, the antenna gain is kept at low values, and most of the input power is consumed to increase the plasma volume until the tube is filled with the plasma whose electron density is higher than the critical electron density required for sustaining the surface wave. On the other hand, the input power is consumed to increase the electron density after the tube is fully filled with the plasma, and the antenna gain increases with increasing the electron density. The dependence of the antenna gain on the electron density is the same as that of a plasma antenna sustained by a DC glow discharge. These results are confirmed by experimental results of the antenna gain and radiation patterns. The antenna gain of the plasma is a few dB smaller than that of the identical metal antenna. The antenna gain of the plasma antenna is sufficient for the wireless communication, although it is difficult to substitute the plasma antenna for metal antennas completely. The plasma antenna is suitable for applications having high affinity with the plasma characteristics such as low interference and dynamic controllability.

  13. Breakthrough Pressure as a Tool to Probe the Characteristics of Silicon-Containing Liquid-Repellent Surfaces (Briefing Charts)

    DTIC Science & Technology

    2014-12-15

    geometry or the equilibrium contact angle. This presentation will explore the use of experimentally‐determined breakthrough pressures (in combination with...surface imaging and apparent contact angle measurements) to infer important geometric and thermodynamic characteristics of liquid repellent surfaces...is unlimited..   Background: Breakthrough Pressure 4 • Typically, a liquid-solid surface contact angle is estimated from existing data, then

  14. Characteristics, seasonal distribution and surface degradation features of microplastic pellets along the Goa coast, India.

    PubMed

    Veerasingam, S; Saha, Mahua; Suneel, V; Vethamony, P; Rodrigues, Andrea Carmelita; Bhattacharyya, Sourav; Naik, B G

    2016-09-01

    Microplastic pellets (MPPs) are ubiquitous contaminants, recognised as a serious threat to the biota in coastal, estuarine and marine environment. The distribution, abundance, weathering and chemical characteristics of MPPs on the beaches of Goa, and their transport to the coast during the southwest (SW) monsoon are discussed in this paper. MPP samples collected from six sandy beaches were categorised based on colour and polymer types using Stereoscope microscope and FTIR-ATR spectroscopy, respectively. White colour MPPs were the most abundant, and Polyethylene (PE) and Polypropylene (PP) were the dominant polymer types of MPPs deposited on all the beaches. Carbonyl index values showed that MPPs collected in June 2015 (representing SW monsoon) were 'new', whereas the MPPs collected in January 2015 were 'aged', showing that MPPs are arriving at Goa coast only during SW monsoon due to conducive hydrodynamic conditions. Characteristics of MPPs suggest that they could be originated primarily from ocean-based sources. The winds and surface currents during SW monsoon are the driving forces for the transportation and deposition of MPPs on the Goa beaches. The results of this study will be useful to the National 'Clean India' program for effective plastic debris removal management.

  15. Optical characteristics of the filamentary and diffuse modes in surface dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Zhang, Ying; Li, Jie; Jiang, Nan; Shang, Ke-Feng; Lu, Na; Wu, Yan

    2016-11-01

    Surface dielectric barrier discharge (DBD) plasmas generally exhibits filamentary and diffuse discharges at atmospheric air. The focus of this investigation is on the different optical characteristics and quantitative research about morphological features of two discharge modes. The temporally and spatially resolved characteristics of discharge phenomenon together with the gas temperature are presented with microsecond time scale. Discharge area is estimated by the sum of pixels that equal to "1" in MATLAB software. The formation of diffuse plasma mainly depends on an increase of the ionization coefficient and a creation of sufficient seed electrons by the Penning effect at low electric fields. Accordingly, experimental measurements show that diffuse discharge during the negative half cycle has good uniformity and stability compared with filamentary discharge during the positive half cycle. The rotational temperatures of plasma are determined by comparing the experimental spectra with the simulated spectra that have been investigated. The plasma gas temperature keeps almost constant in the filamentary discharge phase and subsequently increased by about 115 K during the diffuse discharge. In addition, it is shown to be nearly identical in the axial direction. Non-uniform temperature distribution can be observed in the radial direction with large fluctuations. The plasma length is demonstrated almost the same between two discharge modes.

  16. Effects of muscle fibre shortening on the characteristics of surface motor unit potentials.

    PubMed

    Rodriguez-Falces, Javier; Place, Nicolas

    2014-02-01

    Traditionally, studies dealing with muscle shortening have concentrated on assessing its impact on conduction velocity, and to this end, electrodes have been located between the end-plate and tendon regions. Possible morphologic changes in surface motor unit potentials (MUPs) as a result of muscle shortening have not, as yet, been evaluated or characterized. Using a convolutional MUP model, we investigated the effects of muscle shortening on the shape, amplitude, and duration characteristics of MUPs for different electrode positions relative to the fibre-tendon junction and for different depths of the MU in the muscle (MU-to-electrode distance). It was found that the effects of muscle shortening on MUP morphology depended not only on whether the electrodes were between the end-plate and the tendon junction or beyond the tendon junction, but also on the specific distance to this junction. When the electrodes lie between the end-plate and tendon junction, it was found that (1) the muscle shortening effect is not important for superficial MUs, (2) the sensitivity of MUP amplitude to muscle shortening increases with MU-to-electrode distance, and (3) the amplitude of the MUP negative phase is not affected by muscle shortening. This study provides a basis for the interpretation of the changes in MUP characteristics in experiments where both physiological and geometrical aspects of the muscle are varied.

  17. Semiautomated hybrid algorithm for estimation of three-dimensional liver surface in CT using dynamic cellular automata and level-sets.

    PubMed

    Dakua, Sarada Prasad; Abinahed, Julien; Al-Ansari, Abdulla

    2015-04-01

    Liver segmentation continues to remain a major challenge, largely due to its intense complexity with surrounding anatomical structures (stomach, kidney, and heart), high noise level and lack of contrast in pathological computed tomography (CT) data. We present an approach to reconstructing the liver surface in low contrast CT. The main contributions are: (1) a stochastic resonance-based methodology in discrete cosine transform domain is developed to enhance the contrast of pathological liver images, (2) a new formulation is proposed to prevent the object boundary, resulting from the cellular automata method, from leaking into the surrounding areas of similar intensity, and (3) a level-set method is suggested to generate intermediate segmentation contours from two segmented slices distantly located in a subject sequence. We have tested the algorithm on real datasets obtained from two sources, Hamad General Hospital and medical image computing and computer-assisted interventions grand challenge workshop. Various parameters in the algorithm, such as [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text], play imperative roles, thus their values are precisely selected. Both qualitative and quantitative evaluation performed on liver data show promising segmentation accuracy when compared with ground truth data reflecting the potential of the proposed method.

  18. Design, characterization, and in vitro cellular inhibition and uptake of optimized genistein-loaded NLC for the prevention of posterior capsular opacification using response surface methodology.

    PubMed

    Zhang, Wenji; Li, Xuedong; Ye, Tiantian; Chen, Fen; Sun, Xiao; Kong, Jun; Yang, Xinggang; Pan, Weisan; Li, Sanming

    2013-09-15

    This study was to design an innovative nanostructured lipid carrier (NLC) for drug delivery of genistein applied after cataract surgery for the prevention of posterior capsular opacification. NLC loaded with genistein (GEN-NLC) was produced with Compritol 888 ATO, Gelucire 44/14 and Miglyol 812N, stabilized by Solutol(®) HS15 by melt emulsification method. A 2(4) central composite design of 4 independent variables was performed for optimization. Effects of drug concentration, Gelucire 44/14 concentration in total solid lipid, liquid lipid concentration, and surfactant concentration on the mean particle size, polydispersity index, zeta potential and encapsulation efficiency were investigated. Analysis of variance (ANOVA) statistical test was used to assess the optimization. The optimized GEN-NLC showed a homogeneous particle size of 90.16 nm (with PI=0.33) of negatively charged surface (-25.08 mv) and high encapsulation efficiency (91.14%). Particle morphology assessed by TEM revealed a spherical shape. DSC analyses confirmed that GEN was mostly entrapped in amorphous state. In vitro release experiments indicated a prolonged and controlled genistein release for 72 h. In vitro growth inhibition assay showed an effective growth inhibition of GEN-NLCs on human lens epithelial cells (HLECs). Preliminary cellular uptake test proved a enhanced penetration of genistein into HLECs when delivered in NLC.

  19. Microbial dissolution of hematite and associated cellular fossilization by reduced iron phases: a study of ancient microbe-mineral surface interactions.

    PubMed

    Kolo, Kamal; Konhauser, Kurt; Krumbein, Wolfgang Elisabeth; Ingelgem, Yves Van; Hubin, Annick; Claeys, Philippe

    2009-10-01

    We report here on magnetite- and wustite-encrusted and geometrically oriented microbial-like structures (MLS) attached to the surfaces of hematite (alpha-Fe(2)O(3)) crystals in a banded iron formation. Field emission scanning electron microscope (FE-SEM) and scanning electron microscope (SEM) imaging showed a 3-D network of MLS arranged in 1 microm x approximately 20 microm coccoidal-like chains (CLC) of various geometrical shapes: dichotomous and budding-like protrusions, parallel, intersecting, triangular, or sinusoidal. Individual spheroidal forms ( approximately 1 mum in diameter), some displaying what appears to be division, were also abundant. In addition to their size, morphology, and preferred orientations, a microbial origin of these chains and single spheroidal forms is inferred by the presence of material that resembles extracellular polymeric substances (EPS) extending from the base of the chains along the mineral surface: the attachment sites show circular dissolution pits of about 100 nm diameter. Other thin structures protruding from the CLC are reminiscent of bacterial "nanowires." We were, however, unable to find any extant cells, organic carbon, or even recover DNA from the MLS, which suggests that they, if microbial, are possibly mineralogically replaced casts or mineral encrustations of cells. It is further speculated that, given the nature of the substrate upon which the forms are attached and their preferential orientations, it seems plausible that the "original cells" may have been Fe(III)-reducing bacteria that exploited structural imperfections in the crystal lattice. Importantly, the preservation of the ancient microbial shapes in mineral casts of magnetite, wustite, or both may be an overlooked means by which cellular features in the rock record are retained.

  20. Abundance and Distribution Characteristics of Microplastics in Surface Seawaters of the Incheon/Kyeonggi Coastal Region.

    PubMed

    Chae, Doo-Hyeon; Kim, In-Sung; Kim, Seung-Kyu; Song, Young Kyoung; Shim, Won Joon

    2015-10-01

    Microplastics in marine environments are of emerging concern due to their widespread distribution, their ingestion by various marine organisms, and their roles as a source and transfer vector of toxic chemicals. However, our understanding of their abundance and distribution characteristics in surface seawater (SSW) remains limited. We investigated microplastics in the surface microlayer (SML) and the SSW at 12 stations near-shore and offshore of the Korean west coast, Incheon/Kyeonggi region. Variation between stations, sampling media, and sampling methods were compared based on abundances, size distribution, and composition profiles of microsized synthetic polymer particles. The abundance of microplastics was greater in the SML (152,688 ± 92,384 particles/m(3)) than in SSW and showed a significant difference based on the sampling method for SSWs collected using a hand net (1602 ± 1274 particles/m(3)) and a zooplankton trawl net (0.19 ± 0.14 particles/m(3)). Ship paint particles (mostly alkyd resin polymer) accounted for the majority of microplastics detected in both SML and SSWs, and increased levels were observed around the voyage routes of large vessels. This indicates that polymers with marine-based origins become an important contributor to microplastics in coastal SSWs of this coastal region.

  1. Formation and characteristics of biomimetic mineralo-organic particles in natural surface water

    PubMed Central

    Wu, Cheng-Yeu; Martel, Jan; Wong, Tsui-Yin; Young, David; Liu, Chien-Chun; Lin, Cheng-Wei; Young, John D.

    2016-01-01

    Recent studies have shown that nanoparticles exist in environmental water but the formation, characteristics and fate of such particles remain incompletely understood. We show here that surface water obtained from various sources (ocean, hot springs, and soil) produces mineralo-organic particles that gradually increase in size and number during incubation. Seawater produces mineralo-organic particles following several cycles of filtration and incubation, indicating that this water possesses high particle-seeding potential. Electron microscopy observations reveal round, bacteria-like mineral particles with diameters of 20 to 800 nm, which may coalesce and aggregate to form mineralized biofilm-like structures. Chemical analysis of the particles shows the presence of a wide range of chemical elements that form mixed mineral phases dominated by calcium and iron sulfates, silicon and aluminum oxides, sodium carbonate, and iron sulfide. Proteomic analysis indicates that the particles bind to proteins of bacterial, plant and animal origins. When observed under dark-field microscopy, mineral particles derived from soil-water show biomimetic morphologies, including large, round structures similar to cells undergoing division. These findings have important implications not only for the recognition of biosignatures and fossils of small microorganisms in the environment but also for the geochemical cycling of elements, ions and organic matter in surface water. PMID:27350595

  2. Characteristics of surface layer proteins from two new and native strains of Lactobacillus brevis.

    PubMed

    Mobarak Qamsari, Elahe; Kasra Kermanshahi, Rouha; Erfan, Mohammad; Ghadam, Parinaz; Sardari, Soroush; Eslami, Neda

    2017-02-01

    In this work, some important characteristics of surface layer (S-layer) proteins extracted from two new and native Lactobacillus strains, L.brevis KM3 and L.brevis KM7, were investigated. The presence of S-layer on the external surface of L.brevis KM3 was displayed by thin sectioning and negative staining. SDS-PAGE analysis were shown same dominant protein bands approximately around 48kDa for both S-layer proteins. Moreover, the S-layer reappeared when LiCl treated cells were allowed to grow again. Protein secondary structure and thermal behavior were evaluated by using circular dichroism (CD) and differential scanning calorimetry (DSC), respectively. Both S-layer proteins had high content of β-sheet and low amount of α-helix. The thermograms of lyophilized S-layer proteins of L.brevis KM3 and L.brevis KM7 showed one transition peak at 67.9°C and 59.14°C, respectively. To determine monodispersity of extracted S-layer proteins, dynamic light scattering (DLS) was used. The results indicated that the main population of S-layer molecules in two tested lactobacillus strains were composed of monomer with an expected diameter close to 10nm. Furthermore, Zeta potential measurements were showed positive potential for both S-layer proteins, as expected. Our results could be used as the basis for biotechnological applications of these two new S-layer proteins.

  3. Study on the Generation Characteristics of Dielectric Barrier Discharge Plasmas on Water Surface

    NASA Astrophysics Data System (ADS)

    Liu, Wenzheng; Li, Chuanhui

    2014-01-01

    A new contact glow discharge electrode on the surface of water was designed and employed in this study. Because of the strong field strength in the small air gap formed by the electrode and the water surface, glow discharge plasmas were generated and used to treat waste water. The electric field distribution of the designed electrode model was simulated by MAXWELL 3D® simulation software, and the discharge parameters were measured. Through a series of experiments, we investigated the impact of optimal designs, such as the dielectric of the electrode, immersion depths, and curvature radii of the electrode on the generation characteristics of plasmas. In addition, we designed an equipotential multi-electrode configuration to treat a Methyl Violet solution and observe the discoloration effect. The experimental and simulation results indicate that the designed electrodes can realize glow discharge with a relative low voltage, and the generated plasmas covered a large area and were in stable state. The efficiency of water treatment is improved and optimized with the designed electrodes.

  4. Characteristics of the near-surface atmosphere over the Ross Ice Shelf, Antarctica

    NASA Astrophysics Data System (ADS)

    Cassano, John J.; Nigro, Melissa A.; Lazzara, Matthew A.

    2016-04-01

    Two years of data from a 30 m instrumented tower are used to characterize the near-surface atmospheric state over the Ross Ice Shelf, Antarctica. Stable stratification dominates the surface layer at this site, occurring 83% of the time. The strongest inversions occur for wind speeds less than 4 m s-1 and the inversion strength decreases rapidly as wind speed increases above 4 m s-1. In summer unstable stratification occurs 50% of the time and unstable conditions are observed in every season. A novel aspect of this work is the use of an artificial neural network pattern identification technique, known as self-organizing maps, to objectively identify characteristic potential temperature profiles that span the range of profiles present in the 2 year study period. The self-organizing map clustering technique allows the more than 100,000 observed potential temperature profiles to be represented by just 30 patterns. The pattern-averaged winds show distinct and physically consistent relationships with the potential temperature profiles. The strongest winds occur for the nearly well mixed but slightly stable patterns and the weakest winds occur for the strongest inversion patterns. The weakest wind shear over the depth of the tower occurs for slightly unstable profiles and the largest wind shear occurs for moderately strong inversions. Pattern-averaged log wind profiles are consistent with theoretical expectations. The log wind profiles exhibit a kinked profile for the strongest inversion cases indicative of decoupling of the winds between the bottom and top of the tower.

  5. Formation and characteristics of biomimetic mineralo-organic particles in natural surface water

    NASA Astrophysics Data System (ADS)

    Wu, Cheng-Yeu; Martel, Jan; Wong, Tsui-Yin; Young, David; Liu, Chien-Chun; Lin, Cheng-Wei; Young, John D.

    2016-06-01

    Recent studies have shown that nanoparticles exist in environmental water but the formation, characteristics and fate of such particles remain incompletely understood. We show here that surface water obtained from various sources (ocean, hot springs, and soil) produces mineralo-organic particles that gradually increase in size and number during incubation. Seawater produces mineralo-organic particles following several cycles of filtration and incubation, indicating that this water possesses high particle-seeding potential. Electron microscopy observations reveal round, bacteria-like mineral particles with diameters of 20 to 800 nm, which may coalesce and aggregate to form mineralized biofilm-like structures. Chemical analysis of the particles shows the presence of a wide range of chemical elements that form mixed mineral phases dominated by calcium and iron sulfates, silicon and aluminum oxides, sodium carbonate, and iron sulfide. Proteomic analysis indicates that the particles bind to proteins of bacterial, plant and animal origins. When observed under dark-field microscopy, mineral particles derived from soil-water show biomimetic morphologies, including large, round structures similar to cells undergoing division. These findings have important implications not only for the recognition of biosignatures and fossils of small microorganisms in the environment but also for the geochemical cycling of elements, ions and organic matter in surface water.

  6. Effects of earthworms on surface clogging characteristics of intermittent sand filters.

    PubMed

    Wang, Dong-bo; Zhang, Zi-yun; Li, Xiao-ming; Zheng, Wei; Ding, Yan; Yang, Bo; Yang, Qi; Zeng, Tian-jing; Cao, Jian-bin; Yue, Xiu; Shen, Ting-ting; Zeng, Guang-ming; Deng, Jiu-hua; He, Xun

    2010-01-01

    Intermittent sand filters (ISFs) are effective and economical in treating wastewater, but they are easy to clog up. To explore a feasible and simple method to alleviate clogging, two pilot-scale ISFs were constructed, one of which contained earthworms and the other did not. During the operation, the effects of earthworms on the hydraulic behaviour of ISFs were investigated. The results showed that both ISFs exhibited good performance in wastewater treatment. However, they showed different hydraulic characteristics although operated at the same organic loading rate (approximately 300 g m(-2) d(-1)). The ISF without earthworms clogged only after 53 d operation, and was partially recovered after 7 d resting, but after that, clogging occurred again, and more rapidly than the initial clogging event (40 d). However, water on the medium surface of the ISF with earthworms was not observed during the whole experiments. In addition, 11-13% of effective porosity and 0.015-0.026 cm s(-1) of infiltration rate were measured in the upper 20 cm of the ISF at the end of the experiments. The facts demonstrated that earthworms played a positive role in alleviating clogging and earthworms fed filter could alleviate surface clogging effectively.

  7. Influence of surface characteristics of modified glass beads as model carriers in dry powder inhalers (DPIs) on the aerosolization performance.

    PubMed

    Zellnitz, Sarah; Schroettner, Hartmuth; Urbanetz, Nora Anne

    2015-01-01

    The aim of this work is to investigate the effect of surface characteristics (surface roughness and specific surface area) of surface-modified glass beads as model carriers in dry powder inhalers (DPIs) on the aerosolization, and thus, the in vitro respirable fraction often referred to as fine particle fraction (FPF). By processing glass beads in a ball mill with different grinding materials (quartz and tungsten carbide) and varying grinding time (4 h and 8 h), and by plasma etching for 1 min, glass beads with different shades of surface roughness and increased surface area were prepared. Compared with untreated glass beads, the surface-modified rough glass beads show increased FPFs. The drug detachment from the modified glass beads is also more reproducible than from untreated glass beads indicated by lower standard deviations for the FPFs of the modified glass beads. Moreover, the FPF of the modified glass beads correlates with their surface characteristics. The higher the surface roughness and the higher the specific surface area of the glass beads the higher is the FPF. Thus, surface-modified glass beads make an ideal carrier for tailoring the performance of DPIs in the therapy of asthma and chronically obstructive pulmonary diseases.

  8. Large-eddy simulations of surface roughness parameter sensitivity to canopy-structure characteristics

    DOE PAGES

    Maurer, K. D.; Bohrer, G.; Kenny, W. T.; ...

    2015-04-30

    Surface roughness parameters, namely the roughness length and displacement height, are an integral input used to model surface fluxes. However, most models assume these parameters to be a fixed property of plant functional type and disregard the governing structural heterogeneity and dynamics. In this study, we use large-eddy simulations to explore, in silico, the effects of canopy-structure characteristics on surface roughness parameters. We performed a virtual experiment to test the sensitivity of resolved surface roughness to four axes of canopy structure: (1) leaf area index, (2) the vertical profile of leaf density, (3) canopy height, and (4) canopy gap fraction.more » We found roughness parameters to be highly variable, but uncovered positive relationships between displacement height and maximum canopy height, aerodynamic canopy height and maximum canopy height and leaf area index, and eddy-penetration depth and gap fraction. We also found negative relationships between aerodynamic canopy height and gap fraction, as well as between eddy-penetration depth and maximum canopy height and leaf area index. We generalized our model results into a virtual "biometric" parameterization that relates roughness length and displacement height to canopy height, leaf area index, and gap fraction. Using a decade of wind and canopy-structure observations in a site in Michigan, we tested the effectiveness of our model-driven biometric parameterization approach in predicting the friction velocity over heterogeneous and disturbed canopies. We compared the accuracy of these predictions with the friction-velocity predictions obtained from the common simple approximation related to canopy height, the values calculated with large-eddy simulations of the explicit canopy structure as measured by airborne and ground-based lidar, two other parameterization approaches that utilize varying canopy-structure inputs, and the annual and decadal means of the surface roughness parameters at

  9. Large-eddy simulations of surface roughness parameter sensitivity to canopy-structure characteristics

    NASA Astrophysics Data System (ADS)

    Maurer, K. D.; Bohrer, G.; Kenny, W. T.; Ivanov, V. Y.

    2015-04-01

    Surface roughness parameters, namely the roughness length and displacement height, are an integral input used to model surface fluxes. However, most models assume these parameters to be a fixed property of plant functional type and disregard the governing structural heterogeneity and dynamics. In this study, we use large-eddy simulations to explore, in silico, the effects of canopy-structure characteristics on surface roughness parameters. We performed a virtual experiment to test the sensitivity of resolved surface roughness to four axes of canopy structure: (1) leaf area index, (2) the vertical profile of leaf density, (3) canopy height, and (4) canopy gap fraction. We found roughness parameters to be highly variable, but uncovered positive relationships between displacement height and maximum canopy height, aerodynamic canopy height and maximum canopy height and leaf area index, and eddy-penetration depth and gap fraction. We also found negative relationships between aerodynamic canopy height and gap fraction, as well as between eddy-penetration depth and maximum canopy height and leaf area index. We generalized our model results into a virtual "biometric" parameterization that relates roughness length and displacement height to canopy height, leaf area index, and gap fraction. Using a decade of wind and canopy-structure observations in a site in Michigan, we tested the effectiveness of our model-driven biometric parameterization approach in predicting the friction velocity over heterogeneous and disturbed canopies. We compared the accuracy of these predictions with the friction-velocity predictions obtained from the common simple approximation related to canopy height, the values calculated with large-eddy simulations of the explicit canopy structure as measured by airborne and ground-based lidar, two other parameterization approaches that utilize varying canopy-structure inputs, and the annual and decadal means of the surface roughness parameters at the site

  10. Analysis of land surface parameters and turbulence characteristics over the Tibetan Plateau and surrounding region

    NASA Astrophysics Data System (ADS)

    Wang, Yinjun; Xu, Xiangde; Liu, Huizhi; Li, Yueqing; Li, Yaohui; Hu, Zeyong; Gao, Xiaoqing; Ma, Yaoming; Sun, Jihua; Lenschow, Donald H.; Zhong, Shiyuan; Zhou, Mingyu; Bian, Xindi; Zhao, Ping

    2016-08-01

    Based on the results from 11 flux sites during the third Tibetan Plateau (TP) Experiment (TIPEX III), land surface parameters and the turbulence characteristics of the atmospheric surface layer over the TP and surrounding region are analyzed. Monin-Obukhov similarity theory has been used to calculate the aerodynamic roughness length z0m and the excess resistance to heat transfer kB- 1 = ln(z0m/z0h), and the factors that cause variations of z0m and kB- 1 are investigated. The main drivers for the diurnal variations of surface albedo (α) at different sites are solar elevation, solar radiation, and soil moisture. The eddy correlation method is utilized to inversely calculate bulk transfer coefficients for momentum (CD) and heat (CH) at different sites. The relationships between CD and CH and the wind speed at 10 m follow a power law for unstable stratification. For stable stratification, both CD and CH increase with increasing wind speed when wind speed is less than 5 m/s. Diurnal variations of turbulent fluxes are compared at different sites, and the relationships between turbulent fluxes and other variables are analyzed. Wind speed variance normalized by the friction velocity (σu/u*, σv/u*, σw/u*) for neutral stratification (Cu1, Cv1, Cw1), and temperature and humidity variance normalized by a temperature and humidity scale (σT/T*, σq/q*) under free convection (z/L < -0.1) (CT, Cq) are fitted with similarity relations. The differences in similarity constants (Cu1, Cv1, Cw1, CT, Cq) at different sites are discussed. For stable stratification, cases are divided into weakly stable conditions and intermittent turbulence, and the critical values for these two states are determined. Shear and buoyancy terms in the turbulence kinetic energy equation for different stratifications are analyzed.

  11. Wing surface-jet interaction characteristics of an upper-surface blown model with rectangular exhaust nozzles and a radius flap

    NASA Technical Reports Server (NTRS)

    Bloom, A. M.; Hohlweg, W. C.; Sleeman, W. C., Jr.

    1976-01-01

    The wing surface jet interaction characteristics of an upper surface blown transport configuration were investigated in the Langley V/STOL tunnel. Velocity profiles at the inboard engine center line were measured for several chordwise locations, and chordwise pressure distributions on the flap were obtained. The model represented a four engine arrangement having relatively high aspect ratio rectangular spread, exhaust nozzles and a simple trailing edge radius flap.

  12. Temporal and spatial characteristics of surface ozone depletion events from measurements over the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Halfacre, J. W.; Knepp, T. N.; Stephens, C. R.; Pratt, K. A.; Shepson, P.; Simpson, W. R.; Peterson, P. K.; Walsh, S. J.; Matrai, P. A.; Bottenheim, J. W.; Netcheva, S.; Perovich, D. K.; Richter, A.

    2012-12-01

    Arctic tropospheric ozone depletion events (ODEs) have been studied primarily from coastal sites since the mid 1980s with only a few studies occurring over the Arctic Ocean, the hypothesized site of initiation. Despite a multitude of studies, some basic characteristics of ODEs remain poorly defined, including their temporal, spatial, and meteorological characteristics. Several deployments of autonomous, ice-tethered buoys (O-Buoys) were used to elucidate such characteristics from both the Arctic Ocean and coastal sites. The apparent first order decays imply an ozone lifetime (median of 11 hours) that would correspond to a very large BrO concentration, relative to BrO observations obtained from the buoys. These results suggest that ODEs involve a large, unaccounted for source of bromine atoms, that there is a significant contribution from other mechanisms possibly not involving bromine, or that the majority of observed ODEs represent advection of previously-depleted air to the buoy site, even in the Arctic Ocean. Using backward air mass trajectories, the spatial scales for ODEs (defined by time periods with O3 ≤ 15 nmol/mol) were estimated to be ~1800 km (mode), suggesting that most of the lower troposphere above the Arctic Ocean is frequently, at least partially, depleted of ozone. Using the same method, areas estimated to be highly depleted of O3 (< 10 nmol/mol) had dimensions of ~200-600 km (mode). These events correlate with areas of enhanced column BrO from GOME satellite measurements. These observations point to a heterogeneous boundary layer with localized regions of active, O3-destroying halogen chemistry, interspersed among larger regions of previously depleted air that retain their chemical composition due to a lack of mixing. O-Buoy measurements showed low local wind speed averages during most ODEs (mode of 4 m/s), and no apparent dependence on local temperatures. The ice-tethered O-Buoys provide unique data to study the characteristics of ODEs; however

  13. Surface characteristics of implants influence their bone integration after simultaneous placement of implant and GBR membrane.

    PubMed

    Lima, Luiz A; Fuchs-Wehrle, Anita M; Lang, Niklaus P; Hämmerle, Christoph H F; Liberti, Edson; Pompeu, Eduardo; Todescan, José H

    2003-12-01

    The purpose of this study was to evaluate the influence of titanium surface characteristics on bone integration of implants, and to describe the pattern of peri-implant tissue healing after simultaneous implant placement and guided bone regeneration. In four healthy mongrel dogs mandibular premolars were extracted. Two weeks following full mouth prophylaxis and 4 months after extractions, simultaneous membrane and implant surgeries were performed. Efforts were made to produce bony defects with dimensions of 7 x 7 x 7 mm. Into these, 24 standard ITI implants (diameter = 4.1 mm; length = 8 mm) with either a titanium plasma-sprayed (TPS) or a machined surface (MS) were placed. Although implants were inserted 4 mm into cancellous bone, difficulties in achieving optimal primary stability were encountered. All dogs were maintained on a soft diet. Chlorhexidine rinses were performed three times a week. Full mouth prophylaxis was performed every 2 weeks. In the case of membrane exposure, the membranes were removed prematurely (4-6 or 14-15 weeks after surgery). Two dogs were sacrificed at 16 weeks and two at 24 weeks after surgery. Nondecalcified histologic sections were processed and histometric analyses were carried out. When membranes were removed after 4-6 weeks, a vertical bone growth (VB) of 45-61% of the original defect was noted. After membrane removal at 14-15 weeks, similar VB was observed. However, if membranes were left in situ for 24 weeks, VB was between 79% and 96%. In this group of sites, the VB was 66% at 16 weeks and 86% at 24 weeks. Osseointegration in the regenerated bone area ranged from 12% to 32% for the TPS and from 0.0% to 3.6% for the MS implants at 16 and 24 weeks combined. Osseointegration in the pristine host bone area ranged from 16% to 35% for the TPS and from 0.0% to 11% for the MS sites at 16 and 24 weeks. In conclusion, the fraction of implant-bone integration was much higher in the pristine bone compared to that in the regenerated bone

  14. Aerosol and Surface Deposition Characteristics of Two Surrogates for Bacillus anthracis Spores.

    PubMed

    Bishop, Alistair H; Stapleton, Helen L

    2016-11-15

    that can be used to replicate the dispersal characteristics of the threat agent accurately. This work compares the aerosol dispersal and deposition behaviors of the surrogates Btcry- and B. atrophaeus subsp. globigii Btcry- spores remained in the air for a shorter time, and were markedly more likely to adhere to vertical surfaces, than B. atrophaeus subsp. globigii spores.

  15. Impact of polymer surface characteristics on the microrheological measurement quality of protein solutions - A tracer particle screening.

    PubMed

    Bauer, Katharina Christin; Schermeyer, Marie-Therese; Seidel, Jonathan; Hubbuch, Jürgen

    2016-05-30

    Microrheological measurements prove to be suitable to identify rheological parameters of biopharmaceutical solutions. These give information about the flow characteristics but also about the interactions and network structures in protein solutions. For the microrheological measurement tracer particles are required. Due to their specific surface characteristic not all are suitable for reliable measurement results in biopharmaceutical systems. In the present work a screening of melamine, PMMA, polystyrene and surface modified polystyrene as tracer particles were investigated at various protein solution conditions. The surface characteristics of the screened tracer particles were evaluated by zeta potential measurements. Furthermore each tracer particle was used to determine the dynamic viscosity of lysozyme solutions by microrheology and compared to a standard. The results indicate that the selection of the tracer particle had a strong impact on the quality of the microrheological measurement dependent on pH and additive type. Surface modified polystyrene was the only tracer particle that yielded good microrheological results for all tested conditions. The study indicated that the electrostatic surface charge of the tracer particle had a minor impact than its hydrophobicity. This characteristic was the crucial surface property that needs to be considered for the selection of a suitable tracer particle to achieve high measurement accuracy.

  16. Spatial and temporal distribution characteristics of near-surface CO2 concentration over China based on GOSAT data

    NASA Astrophysics Data System (ADS)

    Zhao, Jing; Cui, Weihong; Sun, Yunhua

    2014-11-01

    To study the spatial and temporal distribution characteristics of near-surface CO2 concentration over China, the data of GOSAT L4B and auxiliary data of Mt Waliguan background observations, population density, total energy consumption (coal) and GDP in 2009 were applied to this study. The ArcGIS Geostatistical Analytical Method was used. The ground-based validation was processed by comparing GOSAT data with Mt Waliguan background observations. The variation characteristics of the near-surface CO2 concentration over China was analysed spatially and temporally. The results show that: GOSAT retrieved near-surface products are consistent with Mt Waliguan ground-based measurement; Near-surface CO2 concentration over China is relatively concentrated, and has significant differences between the East and the West, with a overall characteristic that CO2 concentration in the east of China is high and in the west is low; Near-surface CO2 concentration over China has a significant seasonal variation characteristic, and the monthly average concentration rise to the highest value of 396.512 ppmv in April (spring), which is significantly higher than other seasons, decline to the lowest value of 382.781 ppmv in July (summer); All relationships illustrate a big uncertainty, resulting a conclusion that the reasons causing the spatial distribution of near-surface CO2 concentration may be varied, could not be easily determined as anthropogenic or natural ressons, which need further study.

  17. Effects of Ion Beam on Nanoindentation Characteristics of Glassy Polymeric Carbon Surface

    SciTech Connect

    Rodrigues, M. G.; Da Cruz, N. C.; Rangel, E. C.; Zimmerman, R. L.; Ila, Dr. Daryush; Poker, David B; Hensley, Dale K

    2005-01-01

    Glassy polymeric carbon (GPC) is a useful material for medical applications due to its chemical inertness and biocompatible characteristics. Mitral and aortic and hydrocephalic valves are examples of GPC prosthetic devices that have been fabricated and commercialized in Brazil. In this work, ion beam was used to improve the mechanical characteristics of GPC surface and therefore to avoid the propagation of microcracks where the cardiac valves are more fragile. A control group of phenolic resin samples heat-treated at 300, 400, 700, 1000, 1500, and 2500 C was characterized by measuring their hardness and Young's reduced elastic modulus with the depth of indentation. The control group was compared to results obtained with samples heat-treated at 700, 1000, and 1500 C and bombarded with energetic ions of silicon, carbon, oxygen, and gold at energies of 5, 6, 8, and 10 MeV, respectively, with fluences between 1.0 x 10{sup 13} and 1.0 x 10{sup 16} ions/cm{sup 2}. GPC nonbombarded samples showed that hardness depends on the heat treatment temperature (HTT), with a maximum hardness for heat treatment at 1000 C. The comparison between the control group and bombarded group also showed that hardness, after bombardment, had a greater increase for samples prepared at 700 C than for samples prepared at higher temperatures. The Young's elastic modulus presents an exponential relationship with depth. The parameters obtained by fitting depend on the HTT and on the ion used in the bombardment more than on energy and fluence. The hardness results show clearly that bombardment can promote carbonization, increase the linkage between the chains of the polymeric material, and promote recombination of broken bonds in lateral groups that are more numerous for samples heat-treated at 700 C.

  18. Bone Response to Surface-Modified Titanium Implants: Studies on the Early Tissue Response to Implants with Different Surface Characteristics

    PubMed Central

    Larsson Wexell, C.; Thomsen, P.; Aronsson, B.-O.; Tengvall, P.; Rodahl, M.; Lausmaa, J.; Kasemo, B.; Ericson, L. E.

    2013-01-01

    In a series of experimental studies, the bone formation around systematically modified titanium implants is analyzed. In the present study, three different surface modifications were prepared and evaluated. Glow-discharge cleaning and oxidizing resulted in a highly stoichiometric TiO2 surface, while a glow-discharge treatment in nitrogen gas resulted in implants with essentially a surface of titanium nitride, covered with a very thin titanium oxide. Finally, hydrogen peroxide treatment of implants resulted in an almost stoichiometric TiO2, rich in hydroxyl groups on the surface. Machined commercially pure titanium implants served as controls. Scanning Auger Electron Spectroscopy, Scanning Electron Microscopy, and Atomic Force Microscopy revealed no significant differences in oxide thickness or surface roughness parameters, but differences in the surface chemical composition and apparent topography were observed. After surface preparation, the implants were inserted in cortical bone of rabbits and evaluated after 1, 3, and 6 weeks. Light microscopic evaluation of the tissue response showed that all implants were in contact with bone and had a large proportion of newly formed bone within the threads after 6 weeks. There were no morphological differences between the four groups. Our study shows that a high degree of bone contact and bone formation can be achieved with titanium implants of different surface composition and topography. PMID:24174936

  19. The impact of marine aerosols on atmospheric characteristics over ocean surface in frontal zones

    NASA Astrophysics Data System (ADS)

    Pavlova, Hanna; Palamarchuk, Iuliia; Ruban, Igor; Ivanov, Sergiy

    2015-04-01

    Ocean-derived aerosols are particles produced from the ocean surface and remaining suspended in the atmosphere during a certain period of time. Aerosols act as climate forcers both directly (by scattering and absorbing solar radiation) and indirectly (by affecting cloud microphysics as cloud condensation nuclei). To evaluate the degree of marine aerosols impact on weather conditions the numerical experiments with the HARMONIE model were conducted with the model domain covering area over the North Atlantic. The results showed that marine aerosols have a significant impact on characteristics of the atmosphere (such as air temperature, specific humidity, precipitation, and vertical velocity) over the ocean surface. The most significant differences occur along the frontal zones with high gradients at all vertical levels in the atmosphere for all variables. Change in radiative fluxes leads to changes in temperature of the atmosphere. These anomalies appear as mesoscale cells of opposite signs alternating each other. It can be assumed that they are formed as a result of a chain of factors. Thus, the absorption and scattering of solar radiation in the upper troposphere during daytime, increasing of moisture content and subsequent increase in thermal inertia of the air, and enhanced greenhouse effect at nighttime are acting in different directions on formation of vertical structure and convection conditions. This leads to a strengthening/weakening of the updrafts and compensatory movements, and eventually to the changes in processes of precipitation formation. Thus, the simulation of weather conditions in frontal zones over the ocean requires considering the effect of the marine aerosols presence.

  20. Characteristic Changes in Cell Surface Glycosylation Accompany Intestinal Epithelial Cell (IEC) Differentiation: High Mannose Structures Dominate the Cell Surface Glycome of Undifferentiated Enterocytes.

    PubMed

    Park, Dayoung; Brune, Kristin A; Mitra, Anupam; Marusina, Alina I; Maverakis, Emanual; Lebrilla, Carlito B

    2015-11-01

    Changes in cell surface glycosylation occur during the development and differentiation of cells and have been widely correlated with the progression of several diseases. Because of their structural diversity and sensitivity to intra- and extracellular conditions, glycans are an indispensable tool for analyzing cellular transformations. Glycans present on the surface of intestinal epithelial cells (IEC) mediate interactions with billions of native microorganisms, which continuously populate the mammalian gut. A distinct feature of IECs is that they differentiate as they migrate upwards from the crypt base to the villus tip. In this study, nano-LC/ESI QTOF MS profiling was used to characterize the changes in glycosylation that correspond to Caco-2 cell differentiation. As Caco-2 cells differentiate to form a brush border membrane, a decrease in high mannose type glycans and a concurrent increase in fucosylated and sialylated complex/hybrid type glycans were observed. At day 21, when cells appear to be completely differentiated, remodeling of the cell surface glycome ceases. Differential expression of glycans during IEC maturation appears to play a key functional role in regulating the membrane-associated hydrolases and contributes to the mucosal surface innate defense mechanisms. Developing methodologies to rapidly identify changes in IEC surface glycans may lead to a rapid screening approach for a variety of disease states affecting the GI tract.

  1. Using Surface Electromyography To Assess Sex Differences in Neuromuscular Response Characteristics

    PubMed Central

    Shultz, Sandra J.; Perrin, David H.

    1999-01-01

    Objective: To provide an overview of the continuum of muscular responses that typically occur with joint perturbation. The applications and limitations of surface electromyography (sEMG) in evaluating these responses are also addressed. Research applications assessing sex differences in these neuromuscular response characteristics are discussed along with suggestions for future research. Data Sources: MEDLINE was searched from 1969 through 1998. Sport DISCUS was searched from 1975 through 1998. Terms searched included “anterior cruciate ligament,” “epidemiology,” “neuromuscular control,” “neuromuscular performance,” “electromyography,” “latency,” “reflex,” “electromechanical delay,” “dynamic stability,” “intrinsic stiffness,” “short-range stiffness,” “muscle,” “mechanoreceptors,” and “reaction time.” Data Synthesis: It is widely accepted that efficient neuromuscular control is essential to dynamic joint stability and protection. Many studies have established the significant role of the muscles, and particularly the hamstrings, in providing knee stability. By observing the timing, phasing, and recruitment of reflexive muscular activation after a loading stress to the knee, we can better understand the coordinative mechanisms necessary to protect the joint and prevent ligament injury. A number of research models have employed the use of sEMG to evaluate neuromuscular responses at the knee after joint loading or perturbation. However, very few studies have specifically addressed potential sex differences in these response characteristics. Conclusions/Recommendations: From the limited research available, it appears that a sex difference may exist in some aspects of neuromuscular responses. However, further research is needed to explore these differences at the knee and their potential role as predisposing factors to the higher incidence of anterior cruciate ligament injuries in females. Future studies should

  2. Microbial cell surface characteristics: Elucidating attachment/detachment using hydrophobicity and electrokinetic measurements

    EPA Science Inventory

    The surface properties of microorganisms play an important role in their behavior within the environment. Electrophoretic mobility and cell surface hydrophobicity of bacterial cells influence their initial interaction with surfaces and mediate their stability within an aqueous su...

  3. The transport characteristics of passing fast ions produced by nonlocal overlapping of drift island surfaces and magnetic island surfaces

    NASA Astrophysics Data System (ADS)

    Cao, Jinjia; Gong, Xueyu; Xiang, Dong; Huang, Qianhong; Yu, Jun

    2016-08-01

    The structure of the drift-island surface of passing fast ions (PFIs) is investigated in the presence of the resonant interaction with a magnetic island. Two overlapping regions of the drift-island surface and the magnetic island surface are found, one corresponding to local overlapping region and the other to non-local one. Here, the word "nonlocal" denotes that the resonances in the core plasma can have effects on the PFIs near the plasma boundary, while the "local" represents that the PFIs just near the resonant location are influenced. The nonlocal overlapping constructs a transport path along which the PFIs can become losses. There are three kinds of drift-island surfaces to join in forming the transport paths. A pitch angle region, which is called pitch angle gap, is found near the plasma boundary, where the drift-island surface cannot be formed and few PFIs are lost. The pitch-angle selective features of PFI losses are obtained by analyzing the three kinds of drift-island surfaces. The coupling between the crowd drift island surfaces and the collision can induce the prompt losses of PFIs and rapidly slowing down of PFI energy. The time of the prompt losses and the slowing down rate are calculated. Qualitatively, the theoretical results are in well agreement with the experimental observations in ASDEX Upgrade [M. García-Muñoz et al., Nucl. Fusion 47, L10 (2007)].

  4. Characteristic two-dimensional Fermi surface topology of high-Tc iron-based superconductors.

    PubMed

    Sunagawa, Masanori; Ishiga, Toshihiko; Tsubota, Koji; Jabuchi, Taihei; Sonoyama, Junki; Iba, Keita; Kudo, Kazutaka; Nohara, Minoru; Ono, Kanta; Kumigashira, Hiroshi; Matsushita, Tomohiro; Arita, Masashi; Shimada, Kenya; Namatame, Hirofumi; Taniguchi, Masaki; Wakita, Takanori; Muraoka, Yuji; Yokoya, Takayoshi

    2014-03-14

    Unconventional Cooper pairing originating from spin or orbital fluctuations has been proposed for iron-based superconductors. Such pairing may be enhanced by quasi-nesting of two-dimensional electron and hole-like Fermi surfaces (FS), which is considered an important ingredient for superconductivity at high critical temperatures (high-Tc). However, the dimensionality of the FS varies for hole and electron-doped systems, so the precise importance of this feature for high-Tc materials remains unclear. Here we demonstrate a phase of electron-doped CaFe2As2 (La and P co-doped CaFe2As2) with Tc = 45 K, which is the highest Tc found for the AEFe2As2 bulk superconductors (122-type; AE = Alkaline Earth), possesses only cylindrical hole- and electron-like FSs. This result indicates that FS topology consisting only of two-dimensional sheets is characteristic of both hole- and electron-doped 122-type high-Tc superconductors.

  5. Analysis of characteristics in the sea surface temperature variability in the East/Japan Sea

    NASA Astrophysics Data System (ADS)

    Yeh, Sang-Wook; Park, Young-Gyu; Min, HongSik; Kim, Cheol-Ho; Lee, Jae-Hak

    2010-06-01

    We examine the characteristics of sea surface temperature (SST) variability in the East/Japan Sea (EJS) for the period of 1891-2005 using 1°×1° latitude and longitude resolution datasets from the Japan Meteorological Agency and the Hadley Centre. A significant warming trend that manifests itself more strongly over the southern part of the sea is observed. In addition, it is found in the EJS that warming during the boreal winter is more significant than that during the summer. The EJS SST index, obtained from the time series of monthly SST anomaly averaged over the western half of the EJS, where large SST anomaly standard deviation is observed, has a primary spectral density at a frequency longer than a decade and a secondary peak at the annual frequency band. The variability of the low-frequency EJS SST, which is mostly explained by that during winter, is characterized by significant warming from the early 1940s to the late 1940s and from the mid-1980s to the present. Between the two warming periods, the EJS SST variability is dominated by decadal fluctuations. Finally, we discuss possible mechanisms of the low frequency EJS SST variability in conjunction with atmospheric variability. When the northwesterly winter monsoon becomes weaker (stronger), less (greater) amount of cold air is advected to the EJS. Sensible heat loss from the sea to the air becomes smaller (greater) producing a warm (cold) SST anomaly.

  6. Optical emission characteristics of surface nanosecond pulsed dielectric barrier discharge plasma

    SciTech Connect

    Wu Yun; Li Yinghong; Jia Min; Song Huimin; Liang Hua

    2013-01-21

    This paper reports an experimental study of the optical emission characteristics of the surface dielectric barrier discharge plasma excited by nanosecond pulsed voltage. N{sub 2}(C{sup 3}{Pi}{sub u}) rotational and vibrational temperatures are almost the same with upper electrode powered with positive polarity and lower electrode grounded or upper electrode grounded and lower electrode powered with positive polarity. While the electron temperature is 12% higher with upper electrode powered with positive polarity and lower electrode grounded. When the frequency is below 2000 Hz, there is almost no influence of applied voltage amplitude and frequency on N{sub 2}(C{sup 3}{Pi}{sub u}) rotational, vibrational temperature and electron temperature. As the pressure decreases from 760 Torr to 5 Torr, N{sub 2}(C{sup 3}{Pi}{sub u}) rotational temperature remains almost unchanged, while its vibrational temperature decreases initially and then increases. The discharge mode changes from a filamentary type to a glow type around 80 Torr. In the filamentary mode, the electron temperature remains almost unchanged. In the glow mode, the electron temperature increases while the pressure decreases.

  7. The Characteristic Precipitation and Land Surface Conditions that Lead to Flooding over Different Basin Sizes

    NASA Astrophysics Data System (ADS)

    Li, X.; Troy, T. J.

    2015-12-01

    Flooding occurs across a range of basin sizes, from small catchments to the Mississippi River, and across a range of temporal scales, from flash floods on the order of hours to several weeks. Previous research has primarily focused on scaling of flood peaks, flood processes in catchments, and diagnosis of major events. This research seeks to fill in the gaps between the different studies, by understanding flooding mechanisms across a range of drainage basin size, accounting for precipitation patterns, antecedent soil moisture, and snow. In this study, we use over 250 sub-basins in the Ohio River basin with 60 years of observed precipitation and streamflow and simulated soil moisture and snow with a land surface model. We find that large basins sizes typically have stronger correlation with longer precipitation durations rather than shorter, and vice versa. Soil moisture plays a significant role in determining flooding, but snowmelt also influences the flood generation. Finally, we identify if characteristic precipitation and antecedent moisture conditions lead to floods over different basins sizes. These results have the potential to increase our understanding of flood generation across a range of basin scales, which can then be used to better inform flood predictions under climate change.

  8. Study on Transmission Torque Characteristics of a Surface-Permanent-Magnet-Type Magnetic Gear

    NASA Astrophysics Data System (ADS)

    Niguchi, Noboru; Hirata, Katsuhiro; Hayakawa, Yuichi

    Magnetic gears have some advantages such as low mechanical loss and maintenance-free operation that are not observed in conventional mechanical gears. In addition, magnetic gears have inherent overload protection. Therefore, magnetic gears are expected to be used in special applications; for example, they can be used in a joint of a humanoid robot. Recently, various types of new magnetic gears have been proposed. Among these new gears, a surface-permanent-magnet-type (SPM-type) magnetic gear employing harmonic magnetic flux has gained attention because of its high transmission torque density, though it has a complex structure with multipole magnets. Some studies on an SPM-type magnetic gear have been carried out, but there are few papers on cogging torque. This paper describes the transmission torque characteristics of an SPM-type magnetic gear. The operating principle and the transmission torque under synchronous operation are formulated in accordance with the gear ratio. High orders of the cogging torque are computed by employing the 3-D finite element method, and the validity of the analysis is verified by carrying out measurements on a prototype. Furthermore, a method for reducing the cogging torque is discussed.

  9. Relationships between surface sediment diatom assemblages and lakewater characteristics in Adirondack Lakes

    SciTech Connect

    Charles, D.F.

    1985-06-01

    Relationships between surface sediment diatom assemblages and lakewater characteristics were studied in 38 lakes in the Adirondack Mountains of northern New York. Most of the lakes are dilute, poorly buffered, and oligotrophic to mesotrophic. The diatom flora typical for circumneutral to acidic lakes. The purposes of this study were to identify the environmental factors most strongly related to the distributions of diatom taxa and the overall composition of diatom assemblages, and to derive equations to infer lakewater pH from diatom assemblage data. Relationships between diatom assemblages and environmental gradients were analyzed using reciprocal averaging ordination (RA). Correlations between Ra axis 1 and pH-related factors were strong. Correlations were weaker (but still statistically significant) with elevation, epilimnion temperature, and concentrations of SO/sub 4/, Cl, and Si. Total P, chlorophyll a, water color, and mean depth were not important in explaining differences among assemblages. Predictive equations were derived for inferring lakewater pH from diatom assemblage data. Agreement between predicted and measured pH was very good. These predictive relationships can be used to interpret stratigraphic diatom assemblages to reconstruct lake pH histories.

  10. Surface and physical characteristics of ZnO:Al nanostructured films

    NASA Astrophysics Data System (ADS)

    Fang, Te-Hua; Kang, Shao-Hui

    2009-06-01

    Structural and surface characterizations of the ZnO:Al nanostructured films were achieved by means of x-ray diffraction, scanning electron microscope, atomic force microscope, and nanoindentation measurements. The films exhibited hydrophobic behavior with contact angles of about 133.2°-142.7°, and a decrease in the hardness and Young's modulus with decreasing indentation depths. Buckling behavior took place during the indentation process, and the fracture strength of the films was also investigated. The results show that the phase transformation from zinc blende to wurtzite structure. Also, it should be correlated with belongs to chairtype Peierls distortion with up to 38° tilting (001) rock-salt structure along the (1¯21¯0) plane and followed tilting along the (101¯0) plane by about 32° for a fair match with (101¯0) Zn. A nanogenerator with ZnO nanorods was then fabricated to define its piezoelectric characteristics. The power density per unit substrate area is about 18.3 μW/mm2.

  11. Comparison of the surface dielectric barrier discharge characteristics under different electrode gaps

    NASA Astrophysics Data System (ADS)

    Gao, Guoqiang; Dong, Lei; Peng, Kaisheng; Wei, Wenfu; Li, Chunmao; Wu, Guangning

    2017-01-01

    Currently, great interests are paid to the surface dielectric barrier discharge due to the diverse and interesting application. In this paper, the influences of the electrode gap on the discharge characteristics have been studied. Aspects of the electrical parameters, the optical emission, and the discharge induced gas flow were considered. The electrode gap varied from 0 mm to 21 mm, while the applied AC voltage was studied in the range of 17 kV-27 kV. Results indicate that with the increase of the electrode gap, the variation of discharge voltage exhibits an increasing trend, while the other parameters (i.e., the current, power, and induced flow velocity) increase first, and then decrease once the gap exceeded the critical value. Mechanisms of the electrode gap influencing these key parameters were discussed from the point of equivalent circuit. The experimental results reveal that an optimal discharge gap can be obtained, which is closely related to the applied voltage. Visualization of the induced flow with different electrode gaps was realized by the Schlieren diagnostic technique. Finally, the velocities of induced gas flow determined by the pitot tube were compared with the results of intensity-integral method, and good agreements were found.

  12. Tuning beam power-splitting characteristics through modulating a photonic crystal slab’s output surface

    NASA Astrophysics Data System (ADS)

    Feng, Shuai; Xiao, Ting-Hui; Gan, Lin; Wang, Yi-Quan

    2017-01-01

    Light-beam-splitting characteristics are theoretically and experimentally studied in 2D square-lattice photonic crystals (PhCs) with delicately designed and modulated output surfaces. Compared with the traditional branch-waveguide and self-collimation-type PhC splitters, our proposed structure can not only split the input light beam into different numbers of branches but also realize the adjustment of their relative light intensities in each branch. Moreover, the influence of a light beam’s incident angle on both the output branch beams’ relative intensity and propagation direction is investigated. This proposed light beam splitter is able to work within a broad frequency range, and the propagation directions of the output split beams can be modified with the incident beam’s frequency. In addition, when the PhC device becomes thicker, a kind of light-beam-focusing phenomenon is observed. Advantageously, our light-beam-splitting device has no restriction as to the incident light beam’s location and width, so it is much more convenient and practical for achieving optical connection with other functional devices in complicated, large-scale, all-optical integrated circuits.

  13. The effects of sorting by aeolian processes on the geochemical characteristics of surface materials: a wind tunnel experiment

    NASA Astrophysics Data System (ADS)

    Wang, Xunming; Lang, Lili; Hua, Ting; Zhang, Caixia; Li, Hui

    2017-03-01

    The geochemical characteristics of aeolian and surface materials in potential source areas of dust are frequently employed in environmental reconstructions as proxies of past climate and as source tracers of aeolian sediments deposited in downwind areas. However, variations in the geochemical characteristics of these aeolian deposits that result from near-surface winds are currently poorly understood. In this study, we collected surface samples from the Ala Shan Plateau (a major potential dust source area in Central Asia) to determine the influence of aeolian processes on the geochemical characteristics of aeolian transported materials. Correlation analyses show that compared with surface materials, the elements in transported materials (e.g., Cu, As, Pb, Mn, Zn, Al, Ca, Fe, Ga, K, Mg, P, Rb, Co, Cr, Na, Nb, Si, and Zr) were subjected to significant sorting by aeolian processes, and the sorting also varied among different particle size fractions and elements. Variations in wind velocity were significantly correlated with the contents of Cr, Ga, Sr, Ca, Y, Nd, Zr, Nb, Ba, and Al, and with the Zr/Al, Zr/Rb, K/Ca, Sr/Ca, Rb/Sr, and Ca/Al ratios. Given the great variation in the geochemical characteristics of materials transported under different aeolian processes relative to those of the source materials, these results indicate that considerable uncertainty may be introduced to analyses by using surface materials to trace the potential source areas of aeolian deposits that accumulate in downwind areas.

  14. Surface Characteristics and Traversability of the Gale Crater Mars Science Laboratory Landing Site

    NASA Astrophysics Data System (ADS)

    Golombek, M. P.; Bellutta, P.; Beyer, R. A.; Calef, F. J.; Fergason, R. L.; Hoover, R. H.; Huerta, A.; Kipp, D.; Kirk, R. L.; Parker, T. J.; Sun, Y.; Sladek, H. L.

    2011-12-01

    Comparison of remote sensing data of Gale crater with the existing six landing sites on Mars allows predictions of likely surface characteristics at the Mars Science Laboratory (MSL) landing site. The MSL Gale landing ellipse (25 by 20 km) is located on cratered plains just to the northwest of the central crater mound. Bulk thermal inertia of the Gale ellipse is greater than existing landing sites, suggesting a surface dominated by indurated or cemented surface materials. The albedo of the site is comparable to Viking Lander 1 (VL1) and the dust cover index of the ellipse is comparable to Mars Pathfinder (MPF) suggesting a moderately dusty surface. The identification of sulfates and clays in the lower part of the Gale mound (the area of greatest science interest), however, suggests this area is relatively dust free. Low resolution thermal differencing suggests about 10% rock abundance at the site. About 0.05% of the surface is covered by boulders >1.5 m diameter as measured in high-resolution images (0.3 m/pixel), which extrapolated along model Mars rock size-frequency distributions to derive the area covered by rocks >0.1 m diameter, suggest an equivalent rock abundance of ~6%. MOLA 1.2 km length bidirectional slopes and pulse spread (a measure of the roughness at ~75 m) at Gale are higher than existing landing sites, suggesting Gale is moderately rougher at these length scales. Slopes at 5 m length scale from high-resolution image stereogrammetry (1 m elevation postings) and photoclinometry indicate that Gale is comparable to the roughest of the existing landings sites (MPF and VL1) at this length scale. Four craters comprising ~0.2% of the ellipse area have walls steep enough to be considered inescapable if the rover were unfortunate enough to land within them. Six mesas that cover ~0.1% of the ellipse have slopes that are <45° (the rover stability limit) so all should be escapable. Slopes within the cratered plains rarely exceed 15° so there are few mobility

  15. Structural and chemical characteristics of atomically smooth GaN surfaces prepared by abrasive-free polishing with Pt catalyst

    NASA Astrophysics Data System (ADS)

    Murata, Junji; Sadakuni, Shun; Okamoto, Takeshi; Hattori, Azusa N.; Yagi, Keita; Sano, Yasuhisa; Arima, Kenta; Yamauchi, Kazuto

    2012-06-01

    This paper reports the structural and chemical characteristics of atomically flat gallium nitride (GaN) surfaces prepared by abrasive-free polishing with platinum (Pt) catalyst. Atomic force microscopy revealed regularly alternating wide and narrow terraces with a step height equivalent to that of a single bilayer on the flattened GaN surfaces, which originate from the differences in etching rate of two neighboring terraces. The material removal characteristics of the method for GaN surfaces were investigated in detail. We confirmed that an atomically smooth GaN surface with an extremely small number of surface defects, including pits and scratches, can be achieved, regardless of the growth method, surface polarity, and doping concentration. X-ray photoelectron spectroscopy showed that the flattening method produces clean GaN surfaces with only trace impurities such as Ga oxide and metallic Ga. Contamination with the Pt catalyst was also evaluated using total-reflection X-ray fluorescence analysis. A wet cleaning method with aqua regia is proposed, which markedly eliminates this Pt contamination without affecting the surface morphology.

  16. Concentrations and characteristics of organic carbon in surface water in Arizona: Influence of urbanization

    USGS Publications Warehouse

    Westerhoff, P.; Anning, D.

    2000-01-01

    DOC concentration (p<0.05) and exhibited less variability in concentration than inflows to the reservoirs. Specific ultraviolet absorbance values at 254 nm were typically less than 2 m-1(milligram DOC per liter)-1 and lower than values found in most temperate-region rivers, but specific ultraviolet absorbance values increased during runoff events. Fluorescence measurements indicated that DOC in desert streams typically exhibit characteristics of autochthonous sources; however, DOC in unregulated upland rivers and desert streams experienced sudden shifts from autochthonous to allochthonous sources during runoff events. The urban water system (reservoir systems and wastewater-treatment plants) was found to affect temporal variability in DOC concentration and composition.The influence of urbanization, becoming increasingly common in arid regions, on dissolved organic carbon (DOC) concentrations in surface water resources was studied. DOC concentration and composition, seasonal watershed runoff events, streamflow variations, water management practices, and urban infrastructure in several Arizona watersheds were monitored. Ephemeral sites had the highest DOC levels, and unregulated perennial sites and lower concentrations than unregulated intermittent sites, regulated sites, and sites downstream from wastewater treatment plants. Reservoir outflows and wastewater treatment plant effluent had higher and less variable DOC concentrations than inflows to reservoirs. UV absorbance values, fluorescence measurements, and other indicators suggest that urban water systems (reservoirs and wastewater treatment plants) affect temporal variability in DOC concentration and composition.

  17. Characteristics of the molar surface after removal of cervical enamel projections: comparison of three different rotating instruments

    PubMed Central

    2016-01-01

    Purpose The aim of this study was to evaluate and compare tooth surface characteristics in extracted human molars after cervical enamel projections (CEPs) were removed with the use of three rotating instruments. Methods We classified 60 extracted molars due to periodontal lesion with CEPs into grade I, II, or III, according to the Masters and Hoskins’ criteria. Each group contained 20 specimens. Three rotating instruments were used to remove the CEPs: a piezoelectric ultrasonic scaler, a periodontal bur, and a diamond bur. Tooth surface characteristics before and after removal of the projections were then evaluated with scanning electron microscopy (SEM). We analyzed the characteristics of the tooth surfaces with respect to roughness and whether the enamel projections had been completely removed. Results In SEM images, surfaces treated with the diamond bur were smoothest, but this instrument caused considerable harm to tooth structures near the CEPs. The piezoelectric ultrasonic scaler group produced the roughest surface but caused less harm to the tooth structure near the furcation. In general, the surfaces treated with the periodontal bur were smoother than those treated with the ultrasonic scaler, and the periodontal bur did not invade adjacent tooth structures. Conclusions For removal of grade II CEPs, the most effective instrument was the diamond bur. However, in removing grade III projections, the diamond bur can destroy both adjacent tooth structures and the periodontal apparatus. In such cases, careful use of the periodontal bur may be an appropriate substitute. PMID:27127691

  18. Theoretical studies of positron states and annihilation characteristics at the oxidized Cu(100) surface

    SciTech Connect

    Fazleev, N. G.; Weiss, A. H.

    2013-04-19

    In this work we present the results of theoretical studies of positron surface and bulk states and annihilation probabilities of surface-trapped positrons with relevant core electrons at the oxidized Cu(100) surface under conditions of high oxygen coverage. An ab-initio study of the electronic properties of the Cu(100) missing row reconstructed surface at various on surface and sub-surface oxygen coverages has been performed on the basis of the density functional theory (DFT) using the Dmol3 code and the generalized gradient approximation (GGA). Surface structures in calculations have been constructed by adding oxygen atoms to various surface hollow and sub-surface octahedral sites of the 0.5 monolayer (ML) missing row reconstructed phase of the Cu(100) surface with oxygen coverages ranging from 0.5 to 1.5 ML. The charge redistribution at the surface and variations in atomic structure and chemical composition of the topmost layers associated with oxidation and surface reconstruction have been found to affect the spatial extent and localization of the positron surface state wave function and annihilation probabilities of surface trapped positrons with relevant core electrons. Theoretical results are compared with experimental data obtained from studies of oxidation of the Cu(100) surface using positron annihilation induced Auger electron spectroscopy (PAES). It has been shown that positron annihilation probabilities with Cu 3s and 3p core electrons decrease when total (on-surface and sub-surface) oxygen coverage of the Cu(100) surface increases up to 1 ML. The calculations show that for high oxygen coverage when total oxygen coverage is 1. 5 ML the positron is not bound to the surface.

  19. Spatial and Temporal Variations of Surface Characteristics on the Greenland Ice Sheet as Derived from Passive Microwave Observations

    NASA Technical Reports Server (NTRS)

    Anderson, Mark; Rowe, Clinton; Kuivinen, Karl; Mote, Thomas

    1996-01-01

    The primary goals of this research were to identify and begin to comprehend the spatial and temporal variations in surface characteristics of the Greenland ice sheet using passive microwave observations, physically-based models of the snowpack and field observations of snowpack and firn properties.

  20. Effects of near soil surface characteristics on soil detachment by overland flow in a natural succession grassland

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vegetation restoration probably has great effects on the process of soil detachment. This study was conducted to investigate the effects of near soil surface characteristics on soil detachment by overland flow in a 7-year naturally restored grassland. Four treatments were designed to characterize th...

  1. The Use of Bacterial Adherence to Hydrocarbons (BATH) Assay in Evaluation of the Hydrophobic Surface Characteristics of Potential Water Pathogens

    EPA Science Inventory

    Bacterial adherence to hydrocarbons, BATH, is a method for determining the hydrophobic surface characteristics of bacterial cells. The strain’s affinity for water is evaluated by thoroughly mixing a culture and hydrocarbon suspension and then evaluating the decrease in optical de...

  2. Flame front surface characteristics in turbulent premixed propane/air combustion

    SciTech Connect

    Guelder, O.L.; Smallwood, G.J.; Wong, R.; Snelling, D.R.; Smith, R.; Deschamps, B.M.; Sautet, J.C.

    2000-03-01

    The characteristics of the flame front surfaces in turbulent premixed propane/air flames were investigated. Flame front images were obtained using laser-induced fluorescence (LIF) of OH and Mie scattering on two Bunsen-type burners of 11.2-mm and 22.4-mm diameters. Nondimensional turbulence intensity, u{prime}/S{sub L}, was varied from 0.9 to 15, and the Reynolds number, based on the integral length scale, varied from 40 to 467. Approximately 100 images were recorded for each experimental condition. Fractal parameters (fractal dimension, inner and outer cutoffs) and corresponding standard deviations were determined by analysis of the flame front images using the caliper technique. The fractal dimensions derived from OH and Mie scattering images are almost identical. However, inner and outer cutoffs from OH images are consistently higher than those obtained from Mie scattering. The self-similar region of the flame front wrinkling is about a decade for all flames studied. In the nondimensional turbulence intensity range from 1 to 15, it was found that the mean fractal dimension is about 2.2 and it does not show any dependence on turbulence intensity. This contradicts the findings of the previous studies that showed that the fractal dimension asymptotically reaches to 2.35--2.37 when the nondimensional turbulence intensity u{prime}/S{sub L} exceeds 3. It is shown that the reason for this discrepancy is the image analysis method used in the previous studies. Examples are given to show the inadequacy of the circle method used in previous studies for extraction of fractal parameters from flame front images. The fractal parameters obtained so far, in this and previous studies, are not capable of correctly predicting the turbulent burning velocity using the available fractal area closure model.

  3. Montmorillonite surface properties and sorption characteristics for heavy metal removal from aqueous solutions.

    PubMed

    Ijagbemi, Christianah Olakitan; Baek, Mi-Hwa; Kim, Dong-Su

    2009-07-15

    Surface properties of montmorillonite (MMT) and its adsorption characteristics for heavy metals have been investigated with nickel and copper as sorbate from aqueous solutions. Employing the potentiometric and mass titration techniques in batch experimental methods, the point of zero charge (PZC) and point of zero net proton charge (PZNPC) of MMT edges at different ionic strengths present pH(PZC) and pH(PZNPC) to be 3.4+/-0.2. A crossing point was observed for the proton adsorption vs. pH curves at different ionic strengths of KCl electrolyte and in investigating MMT remediation potentialities as sorbent for heavy metals polluted waters, the effects of heavy metal concentration, pH, MMT dosage, reaction time and temperature for Cu(2+) and Ni(2+) uptake were studied. The sorption of metal ions by MMT was pH dependent and the adsorption kinetics revealed sorption rate could be well fitted by the pseudo-second-order rate model. The data according to mass transfer and intraparticle diffusion models confirmed diffusion of solutes inside the clay particles as the rate-controlling step and more important for the adsorption rate than the external mass transfer. Adsorption isotherms showed that the uptake of Cu(2+) and Ni(2+) could be described by the Langmuir model and from calculations on thermodynamic parameters, the positive Delta G degrees values at different temperatures suggest that the sorption of both metal ions were non-spontaneous. Change in enthalpy (Delta H degrees) for Ni(2+) and Cu(2+) were 28.9 and 13.27 kJ/mol K respectively, hence an endothermic diffusion process, as ion uptake increased with increase in temperature. Values of DeltaS degrees indicate low randomness at the solid/solution interface during the uptake of both Cu(2+) and Ni(2+) by MMT. Montmorillonite has a considerable potential for the removal of heavy metal cationic species from aqueous solution and wastewater.

  4. [Pollution Characteristics and Potential Ecological Risk of Heavy Metals in Urban Surface Water Sediments from Yongkang].

    PubMed

    Qi, Peng; Yu, Shu-quan; Zhang, Chao; Liang, Li-cheng; Che, Ji-lu

    2015-12-01

    In order to understand the pollution characteristics of heavy metals in surface water sediments of Yongkang, we analyzed the concentrations of 10 heavy metals including Ti, Cr, Mn, Co, Ni, Cu, Zn, As, Pb and Fe in 122 sediment samples, explored the underlying source of heavy metals and then assessed the potential ecological risks of those metals by methods of the index of geo-accumulation and the potential ecological risk. The study results showed that: 10 heavy metal contents followed the order: Fe > Ti > Mn > Zn > Cr > Cu > Ph > Ni > As > Co, all heavy metals except for Ti were 1. 17 to 3.78 times higher than those of Zhejiang Jinhua- Quzhou basin natural soils background values; The concentrations of all heavy metals had a significantly correlation between each other, indicating that those heavy metals had similar sources of pollution, and it mainly came from industrial and vehicle pollutions; The pollution extent of heavy metals in sediments by geo-accumulation index (Igeo) followed the order: Cr > Zn > Ni > Cu > Fe > As > Pb >Mn > Ti, thereinto, Cr, Zn, Cu and Ni were moderately polluted or heavily polluted at some sampling sites; The potential ecological risk of 9 heavy metals in sediments were in the following order: Cu > As > Ni > Cr > Pb > Co > Zn > Mn > Ti, Cu and As contributed the most to the total potential ecological risk, accounting for 22.84% and 21. 62% , others had a total of 55.54% , through the ecological risk assessment, 89. 34% of the potential ecological risk indexes ( RI) were low and 10. 66% were higher. The contamination level of heavy metals in Yongkang was slight in total, but was heavy in local areas.

  5. Ultra-strong surface plasmon amplification characteristic of a spaser based on gold-silver core-shell nanorods

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Zhou, Jun; Zhang, Haopeng; Jiang, Tao; Lou, Cibo

    2015-03-01

    We proposed an efficient spaser based on gold-silver core-shell nanorods (NRs) encapsulated by an outer silica shell doped with a gain medium. The optical characteristics of the spaser were numerically simulated based on the finite element method (FEM). The results showed that the localized surface plasmon resonance (LSPR) amplification characteristics of the spaser strongly depend on the thickness of silver shell, the aspect ratio of the inner gold NRs, and the polarization direction of the incident light. And, the maximum absolute value of optical cross-section of the spaser can reach 21,824 μm2, which is about 1115, 523, and 18 times higher than that of spasers based on the gold NRs, the silver NRs, and the silver-gold core-shell NRs, respectively. The ultra-strong surface plasmon amplification characteristics of the spaser have potential applications in optical information storage, high sensitivity biochemical sensing, and medical engineering.

  6. Self-consistent many-electron theory of electron work functions and surface potential characteristics for selected metals

    NASA Technical Reports Server (NTRS)

    Smith, J. R.

    1969-01-01

    Electron work functions, surface potentials, and electron number density distributions and electric fields in the surface region of 26 metals were calculated from first principles within the free electron model. Calculation proceeded from an expression of the total energy as a functional of the electron number density, including exchange and correlation energies, as well as a first inhomogeneity term. The self-consistent solution was obtained via a variational procedure. Surface barriers were due principally to many-body effects; dipole barriers were small only for some alkali metals, becoming quite large for the transition metals. Surface energies were inadequately described by this model, which neglects atomistic effects. Reasonable results were obtained for electron work functions and surface potential characteristics, maximum electron densities varying by a factor of over 60.

  7. Comparative surface and nano-tribological characteristics of nanocomposite diamond-like carbon thin films doped by silver

    SciTech Connect

    Zhang, Han-Shen; Endrino, Jose L.; Anders, Andre

    2008-07-10

    In this study we have deposited silver-containing hydrogenated and hydrogen-free diamond-like carbon (DLC) nanocomposite thin films by plasma immersion ion implantation-deposition methods. The surface and nano-tribological characteristics were studied by x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and nano-scratching experiments. The silver doping was found to have no measurable effect on sp2-sp3 hybridization of the hydrogenated DLC matrix and only a slight effect on the hydrogen-free DLC matrix. The surface topography was analyzed by surface imaging. High- and low-order roughness determined by AFM characterization was correlated to the DLC growth mechanism and revealed the smoothing effect of silver. The nano-tribological characteristics were explained in terms of friction mechanisms and mechanical properties in correlation to the surface characteristics. It was discovered that the adhesion friction was the dominant friction mechanism; the adhesion force between the scratching tip and DLC surface was decreased by hydrogenation and increased by silver doping.

  8. Molecular, Cellular and Pharmaceutical Aspects of bone grafting materials and membranes during maxillary sinus-lift procedures. Part 2: detailed characteristics of the materials.

    PubMed

    Iezzi, Giovanna; Piatelli, Adriano; Giuliani, Alessandra; Mangano, Carlo; Barone, Antonio; Manzon, Licia; Degidi, Marco; Scarano, Antonio; Filippone, Antonella; Perrotti, Vittoria

    2016-12-01

    Various grafts or combination of bone substitute materials have been used in sinus lift procedures. Currently, ongoing developments in several disciplines, from molecular biology and chemistry to computer science and engineering, have contributed to the understanding of biological processes leading to bone healing after the use of bone substitute materials (BSBs) and therefore of the behavior of BSBs. The understanding of the properties of each graft enables individual treatment concepts and therefore allows shift from a simple replacement material to the modern concept of an individually created composite biomaterial. Indeed, the choice of the best BSB still remains crucial for success in maxillary sinus augmentation procedures. The present article provides an overview of most of the materials currently available for sinus lift, with a specific focus on their histological, molecular, cellular and pharmaceutical aspects.

  9. Previous chronic exogenous glucocorticoid administration in vivo does not affect functional characteristics and cellular lifespan of human skin fibroblasts in vitro.

    PubMed

    Pratsinis, Harris; Dimozi, Anastasia; Pilichos, Konstantinos; Tsagarakis, Stylianos; Yiacoumettis, Andreas M; Kletsas, Dimitris

    2011-06-01

    Excess of glucocorticoids (GCs) has been reported to lead to skin atrophy and impaired wound healing. The present study investigates whether human skin fibroblasts suffer permanent damages due to a long-term exposure to GC excess. Fibroblasts obtained from patients being under GC treatment for periods over one year were cultured under standard conditions in vitro, and studied regarding pivotal parameters involved in skin homeostasis and aging, i.e. collagen production, cell proliferation, and cellular replicative lifespan. No statistical differences were observed regarding these functions compared to those of normal human skin fibroblasts. Furthermore, no differences between normal and patient-derived cells were observed regarding their sensitivity to a supra-physiological cortisol concentration. In conclusion, the prolonged exposure of human skin fibroblasts in vivo to high concentrations of exogenously-administered GC does not lead to persistent adverse effects on their physiology.

  10. Influence of surface charge on the transport characteristics of nanowire-field effect transistors in liquid environments

    SciTech Connect

    Nozaki, Daijiro E-mail: research@nano.tu-dresden.de; Kunstmann, Jens; Zörgiebel, Felix; Cuniberti, Gianaurelio

    2015-05-18

    One dimensional nanowire field effect transistors (NW-FETs) are a promising platform for sensor applications. The transport characteristics of NW-FETs are strongly modified in liquid environment due to the charging of surface functional groups accompanied with protonation or deprotonation. In order to investigate the influence of surface charges and ionic concentrations on the transport characteristics of Schottky-barrier NW-FETs, we have combined the modified Poisson-Boltzmann theory with the Landauer-Büttiker transport formalism. For a typical device, the model is able to capture the reduction of the sensitivity of NW-FETs in ionic solutions due to the screening from counter ions as well as a local gating from surface functional groups. Our approach allows to model, to investigate, and to optimize realistic Schottky-barrier NW-FET devices in liquid environment.

  11. Foulant characteristics comparison in recycling cooling water system makeup by municipal reclaimed water and surface water in power plant.

    PubMed

    Ping, Xu; Jing, Wang; Yajun, Zhang; Jie, Wang; Shuai, Si

    2015-01-01

    Due to water shortage, municipal reclaimed water rather than surface water was replenished into recycling cooling water system in power plants in some cities in China. In order to understand the effects of the measure on carbon steel corrosion, characteristics of two kinds of foulant produced in different systems were studied in the paper. Differences between municipal reclaimed water and surface water were analyzed firstly. Then, the weight and the morphology of two kinds of foulant were compared. Moreover, other characteristics including the total number of bacteria, sulfate reducing bacteria, iron bacteria, extracellular polymeric substance (EPS), protein (PN), and polysaccharide (PS) in foulant were analyzed. Based on results, it could be concluded that microbial and corrosive risk would be increased when the system replenished by municipal reclaimed water instead of surface water.

  12. Measurement of fog and haze extinction characteristics and availability evaluation of free space optical link under the sea surface environment.

    PubMed

    Wu, Xiaojun; Wang, Hongxing; Song, Bo

    2015-02-10

    Fog and haze can lead to changes in extinction characteristics. Therefore, the performance of the free space optical link is highly influenced by severe weather conditions. Considering the influential behavior of weather conditions, a state-of-the-art solution for the observation of fog and haze over the sea surface is presented in this paper. A Mie scattering laser radar, with a wavelength of 532 nm, is used to observe the weather conditions of the sea surface environment. The horizontal extinction coefficients and visibilities are obtained from the observation data, and the results are presented in the paper. The changes in the characteristics of extinction coefficients and visibilities are analyzed based on both the short-term (6 days) severe weather data and long-term (6 months) data. Finally, the availability performance of the free space optical communication link is evaluated under the sea surface environment.

  13. Foulant Characteristics Comparison in Recycling Cooling Water System Makeup by Municipal Reclaimed Water and Surface Water in Power Plant

    PubMed Central

    Ping, Xu; Jing, Wang; Yajun, Zhang; Jie, Wang; Shuai, Si

    2015-01-01

    Due to water shortage, municipal reclaimed water rather than surface water was replenished into recycling cooling water system in power plants in some cities in China. In order to understand the effects of the measure on carbon steel corrosion, characteristics of two kinds of foulant produced in different systems were studied in the paper. Differences between municipal reclaimed water and surface water were analyzed firstly. Then, the weight and the morphology of two kinds of foulant were compared. Moreover, other characteristics including the total number of bacteria, sulfate reducing bacteria, iron bacteria, extracellular polymeric substance (EPS), protein (PN), and polysaccharide (PS) in foulant were analyzed. Based on results, it could be concluded that microbial and corrosive risk would be increased when the system replenished by municipal reclaimed water instead of surface water. PMID:25893132

  14. A Facile Method to Modify the Characteristics and Corrosion Behavior of 304 Stainless Steel by Surface Nanostructuring toward Biomedical Applications.

    PubMed

    Thangaraj, Balusamy; Nellaiappan, Sankara Narayanan T S; Kulandaivelu, Ravichandran; Lee, Min Ho; Nishimura, Toshiyasu

    2015-08-19

    The study addresses how surface nanostructuring of AISI 304 stainless steel (SS) by surface mechanical attrition treatment (SMAT) influences its characteristic properties and corrosion behavior in Ringer's solution. SMAT of 304 SS induced plastic deformation, enabled surface nanocrystallization, refined the grain size, transformed the austenite phase to strain induced α'-martensite phase, increased the surface roughness, induced defects/dislocations, imparted compressive residual stresses at the surface, decreased the contact angle, and increased surface energy. The change in properties of 304 SS following treatment using 5 and 8 mm ⌀ balls for 15, 30, 45, and 60 min has caused a deleterious influence on its corrosion resistance in Ringer's solution, while an improvement in corrosion behavior is observed for those treated using 2 mm ⌀ balls. The increase in surface roughness, transformation of the austenite to α'-martensite phase, a higher extent of deformation, and the presence of larger number of defects/dislocations are main factors responsible for the lower corrosion resistance observed for 304 SS treated using 5 and 8 mm ⌀ balls in Ringer's solution. In spite of having these attributes with a relatively lower extent, 304 SS treated using 2 mm ⌀ balls offered a better corrosion resistance and exhibits a better passivity. For those treated using 2 mm ⌀ balls, the ability of the nanocrystalline surface to promote passivation outweighs the deleterious influences caused by the limited amount of deformation and defects/dislocations. Based on the findings of this study, it is recommend that SMAT of 304 SS using 2 mm ⌀ balls for 15-30 min is the optimum condition to achieve the suitable surface profile, surface characteristics with better corrosion resistance.

  15. Surface Characteristics and Adhesion Behavior of Escherichia coli O157:H7: Role of Extracellular Macromolecules

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surface macromolecule cleavage experiments were conducted on enterohaemorrhagic Escherichia coli O157:H7 cells to investigate the influence of these macromolecules on cell surface properties. Electrophoretic mobility, hydrophobicity, and titration experiments were carried out on proteinase K treate...

  16. Vibration characteristics of aluminum surface subjected to ultrasonic waves and their effect on wetting behavior of solder droplets.

    PubMed

    Ma, Lin; Xu, Zhiwu; Zheng, Kun; Yan, Jiuchun; Yang, Shiqin

    2014-03-01

    The vibration characteristics of an aluminum surface subjected to ultrasonic waves were investigated with a combination of numerical simulation and experimental testing. The wetting behavior of solder droplets on the vibrating aluminum surface was also examined. The results show that the vibration pattern of the aluminum surface is inhomogeneous. The amplitude of the aluminum surface exceeds the excitation amplitude in some zones, while the amplitude decreases nearly to zero in other zones. The distribution of the zero-amplitude zones is much less dependent on the strength of the vibration than on the location of the vibration source. The surface of the liquid solder vibrates at an ultrasonic frequency that is higher than the vibration source, and the amplitude of the liquid solder is almost twice that of the aluminum surface. The vibration of the surface of the base metal (liquid solder) correlates with the oxide film removal effect. Significant removal of the oxide film can be achieved within 2s when the amplitude of the aluminum surface is higher than 5.4 μm or when the amplitude of the liquid solder surface is higher than 10.2 μm.

  17. Immobilisation of catalase on the surface of biodegradable starch-based polymers as a way to change its surface characteristics.

    PubMed

    Costa, S A; Reis, R L

    2004-04-01

    In this study, a specific enzyme catalase was immobilised onto the surface of two different biodegradable materials, starch cellulose acetate (SCA) and starch polycrapolactone (SPCL) blends. This immobilisation was achieved by several different routes, mainly by covalent binding and an adsorption method using as activation agents epichlorohydrin, cyanogen bromide (CNBr), and aminopropyltriethoxysilane. The effect of the coupling pH of the enzyme-support reaction was determined in terms of activity recovery (%). The catalase immobilised on SCA showed higher activity recovery (%) for all the methods used as compared with results obtained with SPCL. The immobilisation process using epichlorohydrin as an activation agent and polyethylenimine as a spacer-arm enhanced the stability and the half-lives at pH 7.0, 30 degrees C, for immobilised catalase on both SCA and SPCL. The half-lives were respectively, 1162 and 870 h compared with other treatments and free enzyme (480 h). The free glycerol present in the immobilisation medium was also a factor that contributed toward the better performance regarding the long-term stability at 30 degrees C and neutral pH. The extension of the morphological modifications on the surface of the materials was observed by scanning electron microscopy. In general, the results indicated that the chemical modification with epichlorohydrin could provide a simple and rather efficient technique to modify the starch-based materials' surface that might be useful in several biomedical applications.

  18. Effects of physical and chemical characteristics of surface sediments in the formation of shallow lake algae-induced black bloom.

    PubMed

    Shen, Qiushi; Liu, Cheng; Zhou, Qilin; Shang, Jingge; Zhang, Lei; Fan, ChengXin

    2013-12-01

    Surface sediments are closely related to lake black blooms. The dissolved oxygen (DO) distribution and its penetration depth in surface sediments as well as the migration and transformation of redox sensitive elements such as Fe and S at the sediment-water interface are important factors that could influence the formation of the black bloom. In this study, dredged and undredged sediment cores with different surface properties were used to simulate black blooms in the laboratory. The Micro Profiling System was employed to explore features of the DO and sigmaH2S distribution at the sediment-water interface. Physical and chemical characteristics in sediments and pore waters were also analyzed. The results showed that sediment dredging effectively suppressed the black blooms. In the undredged treatment, DO penetration depth was only 50 microm. Fe(2+) concentrations, sigmaH2S concentrations, and sigmaH2S production rates were remarkably higher in surface sediments and pore waters compared to control and dredged treatments. Furthermore, depletion of DO and accumulation of Fe(2+) and sigmaH2S in surface sediments and pore waters provided favorable redox environments and necessary material sources for the blooms. The study results proved that physical and chemical characteristics in surface sediments are important factors in the formation of the black bloom, and could provide scientific guidance for emergency treatment and long-term pre-control of black blooms.

  19. Oxidative regeneration of toluene-saturated natural zeolite by gaseous ozone: the influence of zeolite chemical surface characteristics.

    PubMed

    Alejandro, Serguei; Valdés, Héctor; Manéro, Marie-Hélène; Zaror, Claudio A

    2014-06-15

    In this study, the effect of zeolite chemical surface characteristics on the oxidative regeneration of toluene saturated-zeolite samples is investigated. A Chilean natural zeolite (53% clinoptilolite, 40% mordenite and 7% quartz) was chemically modified by acid treatment with hydrochloric acid and by ion-exchange with ammonium sulphate. Thermal pre-treatments at 623 and 823K were applied and six zeolite samples with different chemical surface characteristics were generated. Chemical modification of natural zeolite followed by thermal out-gassing allows distinguishing the role of acidic surface sites on the regeneration of exhausted zeolites. An increase in Brønsted acid sites on zeolite surface is observed as a result of ammonium-exchange treatment followed by thermal treatment at 623K, thus increasing the adsorption capacity toward toluene. High ozone consumption could be associated to a high content of Lewis acid sites, since these could decompose ozone into atomic active oxygen species. Then, surface oxidation reactions could take part among adsorbed toluene at Brønsted acid sites and surface atomic oxygen species, reducing the amount of adsorbed toluene after the regenerative oxidation with ozone. Experimental results show that the presence of adsorbed oxidation by-products has a negative impact on the recovery of zeolite adsorption capacity.

  20. Evaluation of the polished surface characteristic of cobalt-chrome castings subsequent to various finishing and polishing techniques.

    PubMed

    Ponnanna, A A; Joshi, S M; Bhat, S; Shetty, P

    2001-01-01

    Finishing and Polishing constitutes an essential requisite after the fabrication of removable partial dentures. Improper finishing and polishing of cast framework will adversely affect the quality of functional units of partial dentures due to reduced dimensions. In this study the polished surface characteristic and loss of weight of the casting were evaluated and compared following different finishing and polishing techniques. A total number of thirty test specimens were cast and each surface finishing and polishing technique was carried out with a high speed polishing motor and an electropolishing unit under standardised conditions. Surface roughness was evaluated by means of a surface roughness analyzing instrument, Perthometer. The loss of weight due to the metal lost was observed on a sensitive electronic balance. The results of polishing technique employed with G3 group revealed better surface characteristic. It may be understood that sandblasting causes initial roughness and the sequence of coarse cylindrical abrasive, Black hard rubber polisher (coarse grit-Dentauram), Grey hard rubber polisher (Med-grit-Dentauram), Green hard rubber polisher (Fine-grit-Dentauram), Grey flexible rubber polisher (Fine grit-Renfert), felt buff with pumice slurry and felt buff with green polishing compound (Degussa) produced improved surface in this case. The loss of weight due to metal lost show concern with technique groups G4, G5, G6. It can be avoided by judicious sandblasting and application of proper grit of abrasive agents.

  1. Surface damage characteristics of CFC and tungsten with repetitive ELM-like pulsed plasma irradiation

    NASA Astrophysics Data System (ADS)

    Kikuchi, Y.; Nishijima, D.; Nakatsuka, M.; Ando, K.; Higashi, T.; Ueno, Y.; Ishihara, M.; Shoda, K.; Nagata, M.; Kawai, T.; Ueda, Y.; Fukumoto, N.; Doerner, R. P.

    2011-08-01

    Surface damage of carbon fiber composite (CFC) and tungsten (W) due to repetitive ELM-like pulsed plasma irradiation has been investigated by using a magnetized coaxial plasma gun. CX2002U CFC and stress-relieved W samples were exposed to repetitive pulsed deuterium plasmas with duration of ˜0.5 ms, incident ion energy of ˜30 eV, and surface absorbed energy density of ˜0.3-0.7 MJ/m2. Bright spots on a CFC surface during pulsed plasma exposures were clearly observed with a high-speed camera, indicating a local surface heating. No melting of a W surface was observed under a single plasma pulse exposure at energy density of ˜0.7 MJ/m2, although cracks were formed. Cracking of the W surface grew with repetitive pulsed plasma exposures. Subsequently, the surface melted due to localized heat absorption.

  2. Sulfur and nitrogen mustards induce characteristic poly(ADP-ribosyl)ation responses in HaCaT keratinocytes with distinctive cellular consequences.

    PubMed

    Mangerich, Aswin; Debiak, Malgorzata; Birtel, Matthias; Ponath, Viviane; Balszuweit, Frank; Lex, Kirsten; Martello, Rita; Burckhardt-Boer, Waltraud; Strobelt, Romano; Siegert, Markus; Thiermann, Horst; Steinritz, Dirk; Schmidt, Annette; Bürkle, Alexander

    2016-02-26

    Mustard agents are potent DNA alkylating agents with mutagenic, cytotoxic and vesicant properties. They include bi-functional agents, such as sulfur mustard (SM) or nitrogen mustard (mustine, HN2), as well as mono-functional agents, such as "half mustard" (CEES). Whereas SM has been used as a chemical warfare agent, several nitrogen mustard derivatives, such as chlorambucil and cyclophosphamide, are being used as established chemotherapeutics. Upon induction of specific forms of genotoxic stimuli, several poly(ADP-ribose) polymerases (PARPs) synthesize the nucleic acid-like biopolymer poly(ADP-ribose) (PAR) by using NAD(+) as a substrate. Previously, it was shown that SM triggers cellular poly(ADP-ribosyl) ation (PARylation), but so far this phenomenon is poorly characterized. In view of the protective effects of PARP inhibitors, the latter have been proposed as a treatment option of SM-exposed victims. In an accompanying article (Debiak et al., 2016), we have provided an optimized protocol for the analysis of the CEES-induced PARylation response in HaCaT keratinocytes, which forms an experimental basis to further analyze mustard-induced PARylation and its functional consequences, in general. Thus, in the present study, we performed a comprehensive characterization of the PARylation response in HaCaT cells after treatment with four different mustard agents, i.e., SM, CEES, HN2, and chlorambucil, on a qualitative, quantitative and functional level. In particular, we recorded substance-specific as well as dose- and time-dependent PARylation responses using independent bioanalytical methods based on single-cell immuno-fluorescence microscopy and quantitative isotope dilution mass spectrometry. Furthermore, we analyzed if and how PARylation contributes to mustard-induced toxicity by treating HaCaT cells with CEES, SM, and HN2 in combination with the clinically relevant PARP inhibitor ABT888. As evaluated by a novel immunofluorescence-based protocol for the detection of

  3. Research on pinching characteristics of electron beams emitted from different cathode surfaces of a rod-pinch diode

    NASA Astrophysics Data System (ADS)

    Gao, Yi; Qiu, Aici; Zhang, Zhong; Zhang, Pengfei; Wang, Zhiguo; Yang, Hailiang

    2010-07-01

    The particle-in-cell code UNIPIC is used to simulate the working process of a rod-pinch diode and investigate the pinching characteristics of electron beams emitted from different cathode surfaces. The simulation results indicate that the electron beam emitted from the upstream surface pinches better than from other surfaces when all the three surfaces emit electrons. The charge-density deposition on the anode surface peaks at the rod tip while the deposited charge density is approximately uniform over the first 15 mm of the rod before rapidly increasing over the last 3 mm, indicating a large axial extent of electron deposition. For the case of single-surface emission, the pinching quality of the electron beam emitted from the downstream surface is better than those from other surfaces. The charge-density deposition peaks at the rod tip and decreases rapidly off the tip. Based on the relationship of Larmor radius, beam's self-magnetic field, and the spatial current distribution, the above simulation results are analyzed theoretically. The experiments are performed on the inductive voltage adder to examine the simulations. By comparing the axial distribution of the radiation on the anode rod measured with the pinhole camera and the on-axis forward x-ray dose measured with the LiF thermoluminescent detectors, the simulation results are verified. The electron emission suppression method and the impedance change for each case are investigated or discussed in this paper.

  4. Nitride chemical passivation of a GaAs (100) Surface: Effect on the electrical characteristics of Au/GaAs surface-barrier structures

    SciTech Connect

    Berkovits, V. L. L'vova, T. V.; Ulin, V. P.

    2011-12-15

    The effect of chemical nitridation of GaAs substrates in a hydrazine-sulfide solution on the electrical characteristics of Au/GaAs Schottky structures has been studied. In nitridation of this kind, a solid passivating gallium nitride film with a monolayer thickness is formed on the surface of GaAs, providing almost direct contact between the semiconductor and the metal deposited on its surface. Au/GaAs structures fabricated on nitride substrates have ideality factors close to unity and are characterized by a narrow scatter of potential barrier heights. Prolonged heating of these structures at 350 Degree-Sign C does not change these parameters. The data obtained show that the nitride monolayer formed on the GaAs surface upon treatment in hydrazidesulfide solutions effectively hinders atomic migration across the metal-semiconductor phase boundary.

  5. Facilitated biological reduction of nitroaromatic compounds by reduced graphene oxide and the role of its surface characteristics

    NASA Astrophysics Data System (ADS)

    Li, Lei; Liu, Qi; Wang, Yi-Xuan; Zhao, Han-Qing; He, Chuan-Shu; Yang, Hou-Yun; Gong, Li; Mu, Yang; Yu, Han-Qing

    2016-07-01

    How reduced graphene oxide (RGO) mediates the reductive transformation of nitroaromatic pollutants by mixed cultures and the role of its surface characteristics were evaluated in this study. Different electron donors were applied to investigate the interaction between RGO and anaerobic microbes. Moreover, the influence of the surface properties of RGO on biological nitroaromatic removal was further elucidated. The results show that RGO could achieve an approximate one-fold rate increase of nitrobenzene reduction by mixed culture with glucose as an electron donor. Selective elimination of oxygen moieties on the RGO surface, such as quinone groups, decreased the nitrobenzene transformation rate, whereas doping nitrogen into the RGO framework exhibited a positive effect. The study indicates that graphene-based carbon nanomaterials have the potential to accelerate the biological transformation of nitroaromatic compounds and that the functionalization of these carbon nanomaterials, especially through surface modification, would further enhance the conversion efficiency of contaminants.

  6. Facilitated biological reduction of nitroaromatic compounds by reduced graphene oxide and the role of its surface characteristics

    PubMed Central

    Li, Lei; Liu, Qi; Wang, Yi-Xuan; Zhao, Han-Qing; He, Chuan-Shu; Yang, Hou-Yun; Gong, Li; Mu, Yang; Yu, Han-Qing

    2016-01-01

    How reduced graphene oxide (RGO) mediates the reductive transformation of nitroaromatic pollutants by mixed cultures and the role of its surface characteristics were evaluated in this study. Different electron donors were applied to investigate the interaction between RGO and anaerobic microbes. Moreover, the influence of the surface properties of RGO on biological nitroaromatic removal was further elucidated. The results show that RGO could achieve an approximate one-fold rate increase of nitrobenzene reduction by mixed culture with glucose as an electron donor. Selective elimination of oxygen moieties on the RGO surface, such as quinone groups, decreased the nitrobenzene transformation rate, whereas doping nitrogen into the RGO framework exhibited a positive effect. The study indicates that graphene-based carbon nanomaterials have the potential to accelerate the biological transformation of nitroaromatic compounds and that the functionalization of these carbon nanomaterials, especially through surface modification, would further enhance the conversion efficiency of contaminants. PMID:27439321

  7. Surface characteristics of Ti-6Al-4V alloy by EDM with Cu-SiC composite electrode

    NASA Astrophysics Data System (ADS)

    Li, L.; Feng, L.; Bai, X.; Li, Z. Y.

    2016-12-01

    Ti-6Al-4V alloy is widely used in many industries due to its outstanding properties. However, it has poor machinability using conventional mechanical cutting process. Electrical discharge machining is an alternative competitive process to machine titanium alloy by electrical erosion. This article studies the machining characteristics of Ti-6Al-4V with Cu-SiC composite electrode. Surface topography, subsurface microstructure, energy dispersive spectroscopy analysis, and micro-hardness have been analyzed. The machined surfaces show irregular compound structures, droplets of debris, shallow craters, and micro-pores. The surfaces processed by Cu-SiC electrode have fewer number of microcracks compared with that by Cu electrode. Continuous and uniform hardened layer can be achieved by Cu-SiC electrode. The hardened layer has significantly higher hardness than the bulk material because the new phases of TiC and TiSi2 were created on the surface.

  8. Comparison of surface characteristics of retrieved cobalt-chromium femoral heads with and without ion implantation.

    PubMed

    McGrory, Brian J; Ruterbories, James M; Pawar, Vivek D; Thomas, Reginald K; Salehi, Abraham B

    2012-01-01

    Nitrogen ion implantation of CoCr is reported to produce increased surface hardness and a lower friction surface. Femoral heads with and without ion implantation retrieved from 1997 to 2003 were evaluated for surface roughness (average surface roughness [Ra], mean peak height [Rpm], and maximum distance from peak to valley [Rmax]), nanohardness, and the ion-treated layer thickness. The difference in average Rmax (P = .033) and average Rpm (P = .008) was statistically significant, but there was no correlation between the average or maximum roughness parameters (average surface roughness, Rmax, and Rpm) and time in vivo (P > .05). Overall, nanohardness was greater for the low-friction ion-treated heads (P < .001); and it decreased with increasing time in vivo (P = .01). Ion treatment produces an increased surface hardness, but the advantage of this increased hardness appears to dissipate over time in vivo.

  9. Evaluation of Surface and Near-Surface Melt Characteristics on the Greenland Ice Sheet using MODIS and QuikSCAT Data

    NASA Technical Reports Server (NTRS)

    Hall, Dorothy K.; Nghiem, Son V.; Schaaf, Crystal B.; DiGirolamo, Nicolo E.

    2009-01-01

    The Greenland Ice Sheet has been the focus of much attention recently because of increasing melt in response to regional climate warming. To improve our ability to measure surface melt, we use remote-sensing data products to study surface and near-surface melt characteristics of the Greenland Ice Sheet for the 2007 melt season when record melt extent and runoff occurred. Moderate Resolution Imaging Spectroradiometer (MODIS) daily land-surface temperature (LST), MODIS daily snow albedo, and a special diurnal melt product derived from QuikSCAT (QS) scatterometer data, are all effective in measuring the evolution of melt on the ice sheet. These daily products, produced from different parts of the electromagnetic spectrum, are sensitive to different geophysical features, though QS- and MODIS-derived melt generally show excellent correspondence when surface melt is present on the ice sheet. Values derived from the daily MODIS snow albedo product drop in response to melt, and change with apparent grain-size changes. For the 2007 melt season, the QS and MODIS LST products detect 862,769 square kilometers and 766,184 square kilometers of melt, respectively. The QS product detects about 11% greater melt extent than is detected by the MODIS LST product probably because QS is more sensitive to surface melt, and can detect subsurface melt. The consistency of the response of the different products demonstrates unequivocally that physically-meaningful melt/freeze boundaries can be detected. We have demonstrated that these products, used together, can improve the precision in mapping surface and near-surface melt extent on the Greenland Ice Sheet.

  10. Surface flashover characteristic of disc-type spacer system initiated by wedge shaped gas gap and its improvement

    SciTech Connect

    Hama, H.; Yamamoto, H.; Sakuma, S.; Takatsuka, K.; Yamauchi, T. )

    1993-07-01

    The surface flash over characteristics initiated by the local field intensification have been investigated for lightning impulse, switching impulse and ac voltages, using disc-type model spacer systems with the wedge shaped gas gap formed between the spacer flange and the earth sheath end. The surface flash over voltages of the systems have been evaluated by the simple theory in SF[sub 6] gas and compared with the experimental results. The practical methods by the thin dielectric coating of a low permittivity material on the sheath ends and by the shielding sheath ends protruded inwardly are effective in improving the dielectric performance of the system.

  11. Dual-Enzyme Characteristics of Polyvinylpyrrolidone-Capped Iridium Nanoparticles and Their Cellular Protective Effect against H2O2-Induced Oxidative Damage.

    PubMed

    Su, Hua; Liu, Dan-Dan; Zhao, Meng; Hu, Wei-Liang; Xue, Shan-Shan; Cao, Qian; Le, Xue-Yi; Ji, Liang-Nian; Mao, Zong-Wan

    2015-04-22

    Polyvinylpyrrolidone-stabilized iridium nanoparticles (PVP-IrNPs), synthesized by the facile alcoholic reduction method using abundantly available PVP as protecting agents, were first reported as enzyme mimics showing intrinsic catalase- and peroxidase-like activities. The preparation procedure was much easier and more importantly, kinetic studies found that the catalytic activity of PVP-IrNPs was comparable to previously reported platinum nanoparticles. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) characterization indicated that PVP-IrNPs had the average size of approximately 1.5 nm and mainly consisted of Ir(0) chemical state. The mechanism of PVP-IrNPs' dual-enzyme activities was investigated using XPS, Electron spin resonance (ESR) and cytochrome C-based electron transfer methods. The catalase-like activity was related to the formation of oxidized species Ir(0)@IrO2 upon reaction with H2O2. The peroxidase-like activity originated from their ability acting as electron transfer mediators during the catalysis cycle, without the production of hydroxyl radicals. Interestingly, the protective effect of PVP-IrNPs against H2O2-induced cellular oxidative damage was investigated in an A549 lung cancer cell model and PVP-IrNPs displayed excellent biocompatibility and antioxidant activity. Upon pretreatment of cells with PVP-IrNPs, the intracellular reactive oxygen species (ROS) level in response to H2O2 was decreased and the cell viability increased. This work will facilitate studies on the mechanism and biomedical application of nanomaterials-based enzyme mimic.

  12. Identification and prioritization of candidate genes for symptom variability in breast cancer survivors based on disease characteristics at the cellular level

    PubMed Central

    Koleck, Theresa A; Conley, Yvette P

    2016-01-01

    Research is beginning to suggest that the presence and/or severity of symptoms reported by breast cancer survivors may be associated with disease-related factors of cancer. In this article, we present a novel approach to the identification and prioritization of biologically plausible candidate genes to investigate relationships between genomic variation and symptom variability in breast cancer survivors. Cognitive dysfunction is utilized as a representative breast cancer survivor symptom to elucidate the conceptualization of and justification for our cellular, disease-based approach to address symptom variability in cancer survivors. Initial candidate gene identification was based on genes evaluated as part of multigene expression profiles for breast cancer, which are commonly used in the clinical setting to characterize the biology of cancer cells for the purpose of describing overall tumor aggressiveness, prognostication, and individualization of therapy. A list of genes evaluated within five multigene expression profiles for breast cancer was compiled. In order to prioritize candidate genes for investigation, genes used in each profile were compared for duplication. Twenty-one genes (BAG1, BCL2, BIRC5, CCNB1, CENPA, CMC2, DIAPH3, ERBB2, ESR1, GRB7, MELK, MKI67, MMP11, MYBL2, NDC80, ORC6, PGR, RACGAP1, RFC4, RRM2, and SCUBE2) are utilized in two or more profiles, including five genes (CCNB1, CENPA, MELK, MYBL2, and ORC6) used in three profiles. To ensure that the parsimonious 21 gene set is representative of the more global biological hallmarks of cancer, an Ingenuity Pathway Analysis was conducted. Evaluation of genes known to impact pathways involved with cancer development and progression provide a means to evaluate the overlap between the biological underpinnings of cancer and symptom development within the context of cancer. PMID:27022301

  13. Room Temperature Characteristics of Polymer-Based Low Ice Adhesion Surfaces

    PubMed Central

    He, Zhiwei; Vågenes, Elisabeth T.; Delabahan, Chrisrosemarie; He, Jianying; Zhang, Zhiliang

    2017-01-01

    Ice adhesion is mainly dictated by surface properties, and water wettability is frequently correlated with ice adhesion strength. However, these established correlations are limited to high ice adhesion and become invalid when the ice adhesion strength is low. Here we carried out an experimental study to explore the relationships between low ice adhesion strength and room temperature surface properties. A variety of room temperature properties of 22 polymer-based hydrophilic and hydrophobic samples consisting of both low and high ice adhesion surfaces were analysed. The properties investigated include water adhesion force, water wettability, roughness, elastic modulus and hardness. Our results show that low ice adhesion strength does not correlate well with water contact angle and its variants, surface roughness and hardness. Low elastic modulus does not guarantee low ice adhesion, however, surfaces with low ice adhesion always show low elastic modulus. Low ice adhesion (below 60 kPa) of tested surfaces may be determinative of small water adhesion force (from 180 to 270 μN). Therefore, measurement of water adhesion force may provide an effective strategy for screening anti-icing or icephobic surfaces, and surfaces within specific values of water adhesion force will possibly lead to a low ice adhesion. PMID:28169370

  14. Room Temperature Characteristics of Polymer-Based Low Ice Adhesion Surfaces.

    PubMed

    He, Zhiwei; Vågenes, Elisabeth T; Delabahan, Chrisrosemarie; He, Jianying; Zhang, Zhiliang

    2017-02-07

    Ice adhesion is mainly dictated by surface properties, and water wettability is frequently correlated with ice adhesion strength. However, these established correlations are limited to high ice adhesion and become invalid when the ice adhesion strength is low. Here we carried out an experimental study to explore the relationships between low ice adhesion strength and room temperature surface properties. A variety of room temperature properties of 22 polymer-based hydrophilic and hydrophobic samples consisting of both low and high ice adhesion surfaces were analysed. The properties investigated include water adhesion force, water wettability, roughness, elastic modulus and hardness. Our results show that low ice adhesion strength does not correlate well with water contact angle and its variants, surface roughness and hardness. Low elastic modulus does not guarantee low ice adhesion, however, surfaces with low ice adhesion always show low elastic modulus. Low ice adhesion (below 60 kPa) of tested surfaces may be determinative of small water adhesion force (from 180 to 270 μN). Therefore, measurement of water adhesion force may provide an effective strategy for screening anti-icing or icephobic surfaces, and surfaces within specific values of water adhesion force will possibly lead to a low ice adhesion.

  15. Room Temperature Characteristics of Polymer-Based Low Ice Adhesion Surfaces

    NASA Astrophysics Data System (ADS)

    He, Zhiwei; Vågenes, Elisabeth T.; Delabahan, Chrisrosemarie; He, Jianying; Zhang, Zhiliang

    2017-02-01

    Ice adhesion is mainly dictated by surface properties, and water wettability is frequently correlated with ice adhesion strength. However, these established correlations are limited to high ice adhesion and become invalid when the ice adhesion strength is low. Here we carried out an experimental study to explore the relationships between low ice adhesion strength and room temperature surface properties. A variety of room temperature properties of 22 polymer-based hydrophilic and hydrophobic samples consisting of both low and high ice adhesion surfaces were analysed. The properties investigated include water adhesion force, water wettability, roughness, elastic modulus and hardness. Our results show that low ice adhesion strength does not correlate well with water contact angle and its variants, surface roughness and hardness. Low elastic modulus does not guarantee low ice adhesion, however, surfaces with low ice adhesion always show low elastic modulus. Low ice adhesion (below 60 kPa) of tested surfaces may be determinative of small water adhesion force (from 180 to 270 μN). Therefore, measurement of water adhesion force may provide an effective strategy for screening anti-icing or icephobic surfaces, and surfaces within specific values of water adhesion force will possibly lead to a low ice adhesion.

  16. Evaluation of surface water characteristics of novel daily disposable contact lens materials, using refractive index shifts after wear

    PubMed Central

    Schafer, Jeffery; Steffen, Robert; Reindel, William; Chinn, Joseph

    2015-01-01

    Purpose Contact lens wearers today spend much time using digital display devices. Contact lens manufacturers are challenged to develop products that account for longer periods of time where blink rate is reduced and tear-film evaporation rate is increased, affecting both visual acuity and comfort. Two manufacturers recently introduced novel daily disposable contact lenses with high surface water content. The objective of the present study was to compare surface water characteristics before and after initial wear of recently introduced nesofilcon A and delefilcon A high surface water lenses with those of etafilcon A lenses. Patients and methods Twenty healthy subjects wore each of the three lens types studied in a randomly determined order for 15 minutes. After each wearing, lenses were removed and the surface refractive index (RI) of each lens was immediately measured. Results The mean RI of the unworn delefilcon A lens was 1.34, consistent with water content in excess of 80%. After 15 minutes of wear, the surface RI shifted to 1.43, consistent with its reported 33% bulk water content. In contrast, the mean surface RI of the nesofilcon A lens was 1.38, both initially and after 15 minutes of wear, and that of the etafilcon A lens was 1.41 initially and 1.42 after 15 minutes of wear. Conclusion The surface of the delefilcon A lens behaves like a high water hydrogel upon insertion but quickly dehydrates to behave like its low-water silicone-hydrogel bulk material with respect to surface water content during wear, while both nesofilcon A and etafilcon A lenses maintain their water content during initial wear. The nesofilcon A lens appears unique among high water lenses in maintaining high surface and bulk water content during wear. This is important because changes in surface RI due to dehydration are reported to lead to visual aberration affecting user experience. PMID:26543349

  17. [Spatial characteristics of grain size of surface sediments in mangrove wetlands in Gaoqiao of Zhanjiang, Guangdong province of South China].

    PubMed

    Zhu, Yao-Jun; Bourgeois, C; Lin, Guang-Xuan; Wu, Xiao-Dong; Guo, Ju-Lan; Guo, Zhi-Hua

    2012-08-01

    Mangrove wetland is an important type of coastal wetlands, and also, an important sediment trap. Sediment is an essential medium for mangrove recruitment and development, which records the environmental history of mangrove wetlands and can be used for the analysis of material sources and the inference of the materials depositing process, being essential to the ecological restoration and conservation of mangrove. In this paper, surface sediment samples were collected along a hydrodynamic gradient in Gaoqiao, Zhanjiang Mangrove National Nature Reserve in 2011. The characteristics of the surface sediments were analyzed based on grain size analysis, and the prediction surfaces were generated by the geo-statistical methods with ArcGIS 9.2 software. A correlation analysis was also conducted on the sediment organic matter content and the mangrove community structure. In the study area, clay and silt dominated the sediment texture, and the mean content of sand, silt, and clay was (27.8 +/- 15.4)%, (40.3 +/- 15.4)%, and (32.1 +/- 11.4)%, respectively. The spatial gradient of the sediment characteristics was expressed in apparent interpolation raster. With increasing distance from the seawall, the sediment sand content increased, clay content decreased, and silt content was relatively stable at a certain level. There was a positive correlation between the contents of sediment organic matter and silt, and a negative correlation between the contents of sediment organic matter and sand. Much more sediment organic matter was located at the high tide area with weak tide energy. There existed apparent discrepancies in the characteristics of the surface sediments in different biotopes. The sediment characteristics had definite correlations with the community structure of mangroves, reflecting the complicated correlations between the hydrodynamic conditions and the mangroves.

  18. Surface Chemistry Manipulation of Gold Nanorods Displays High Cellular Uptake In Vitro While Preserving Optical Properties for Bio-Imaging and Photo-Thermal Applications

    DTIC Science & Technology

    2016-03-28

    PROPERTIES FOR BIO-IMAGING AND PHOTO-THERMAL APPLICATIONS ANTHONY B. POLITO III, Maj, USAF, BSC, PhD, MT(ASCP)SBB March 2016 Final Report for March...HIGH CELLULAR UPTAKE IN VITRO WHILE PRESERVING OPTICAL PROPERTIES FOR BIO-IMAGING AND PHOTO-THERMAL APPLICATIONS . 5a. CONTRACT NUMBER 5b...NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Air Force Institute of Technology (AFIT) Civilian Institution

  19. Metrological characteristics of the flat voltammetric electrode in time domain with a reversible electrochemical reaction running on the surface

    NASA Astrophysics Data System (ADS)

    Suchocki, Krzysztof

    2016-11-01

    The study deals with metrological characteristics of the flat voltammetric electrode used for determination of ions concentration by the DC voltammetric method, where a reversible reaction of electrochemical oxidation/reduction takes place on the surface. The analysis shows that such voltammetric electrode acts as a transducer of the first order, where the input signal is a concentration of marked ions in tested solution and the output signal is the current associated with a reversible reaction of oxidation / reduction. Metrological characteristics of such electrode in the time domain are determined by its sensitivity and time constant. The values of these parameters are defined by measurements of characteristics of the voltammetric electrode, polarization voltage and marked ions. To determine the effect of a particular volume of each of these parameters several numerical simulations are presented.

  20. [Surface characteristics of alkali modified activated carbon and the adsorption capacity of methane].

    PubMed

    Zhang, Meng-Zhu; Li, Lin; Liu, Jun-Xin; Sun, Yong-Jun; Li, Guo-Bin

    2013-01-01

    Coconut shell based activated carbon was modified by alkali with different concentrations. The surface structures of tested carbons were observed and analyzed by SEM and BET methods. Boehm's titration and SEM/EDS methods were applied to assay the functional groups and elements on the carbon surface. The adsorption of methane on tested carbons was investigated and adsorption behavior was described by the adsorption isotherms. Results showed that surface area and pore volume of modified carbon increased and surface oxygen groups decreased as the concentration of the alkali used increased, with no obvious change in pore size. When concentration of alkali was higher than 3.3 mol x L(-1), the specific surface area and pore volume of modified carbon was larger than that of original carbon. Methane adsorption capacity of alkali modified carbon increased 24%. Enlargement of surface area and pore volume, reduction of surface oxygen groups will benefit to enhance the methane adsorption ability on activated carbon. Adsorption behavior of methane followed the Langmuir isotherm and the adsorption coefficient was 163.7 m3 x mg(-1).

  1. Surface water and groundwater characteristics in the wetlands of the Ajó River (Argentina)

    NASA Astrophysics Data System (ADS)

    Carol, E. S.; Dragani, W. C.; Kruse, E. E.; Pousa, J. L.

    2012-10-01

    Intertidal wetlands are complex hydrological environments in which surface water and groundwater interact periodically with tidal flows. This work analyzes how the tidal flow determines the hydrodynamics and salinity of surface water and groundwater at different depths in the intertidal wetland located in the marsh of the Ajó River. Water level and salinity measurements were obtained from the Ajó River, the channels discharging into the river and the phreatic aquifer. The results in the natural marsh indicate the presence of saline stratification and that the surface water-groundwater relationship varies with the tide. At low tide, the water table discharges into the surface watercourses, and when the high tide rises above the regional groundwater discharge level, the tidal flow contributes to the water table, which causes an increase in salinity in surface water and groundwater. When the high tide does not rise above the discharge level, the tidal flow only enters the groundwater at the mouth section and the salinity of the surface water and groundwater decreases from low tide to high tide. In the marsh areas excluded from the tidal cycle due to the presence of floodgates, the water table always discharges into the canals, and in the surface water and groundwater there is no presence of saline stratification. The results obtained make it possible to generate a conceptual model of hydrological behaviour which shows the hydrodynamic and hydrochemical complexity of intertidal wetlands.

  2. Surface and buildup dose characteristics for 6, 10, and 18 MV photons from an Elekta Precise linear accelerator.

    PubMed

    Klein, Eric E; Esthappan, Jacqueline; Li, Zuofeng

    2003-01-01

    Understanding head scatter characteristics of photon beams is vital to properly commission treatment planning (TP) algorithms. Simultaneously, having definitive surface and buildup region dosimetry is important to optimize bolus. The Elekta Precise linacs have unique beam flattening filter configurations for each photon beam (6, 10, and 18 MV) in terms of material and location. We performed a comprehensive set of surface and buildup dose measurements with a thin window parallel-plate (PP) chamber to examine effects of field size (FS), source-to-skin distance (SSD), and attenuating media. Relative ionization data were converted to fractional depth dose (FDD) after correcting for bias effects and using the Gerbi method to account for chamber characteristics. Data were compared with a similar vintage Varian linac. At short SSDs the surface and buildup dose characteristics were similar to published data for Varian and Elekta accelerators. The FDD at surface (FDD(0)) for 6, 10, and 18 MV photons was 0.171, 0.159, and 0.199, respectively, for a 15x15 cm2, 100 cm SSD field. A blocking tray increased FDD(0) to 0.200, 0.200, and 0.256, while the universal wedge decreased FDD(0) to 0.107, 0.124, and 0.176. FDD(0) increased linearly with FS (approximately 1.16%/cm). FDD(0) decreased exponentially for 10 and 18 MV with increasing SSD. However, the 6 MV FDD(0) actually increased slightly with increasing SSD. This is likely due to the unique distal flattening filter for 6 MV. The measured buildup curves have been used to optimize TP calculations and guide bolus decisions. Overall the FDD(0) and buildup doses were very similar to published data. Of interest were the relatively low 10 MV surface doses, and the 6 MV FDD(0)'s dependence on SSD.

  3. Surface activity and molecular characteristics of cuttlefish skin gelatin modified by oxidized linoleic acid.

    PubMed

    Aewsiri, Tanong; Benjakul, Soottawat; Visessanguan, Wonnop; Wierenga, Peter A; Gruppen, Harry

    2011-05-01

    Surface activity and molecular changes of cuttlefish skin gelatin modified with oxidized linoleic acid (OLA) prepared at 60, 70 and 80 °C at different times were investigated. Modification of gelatin with OLA could improve surface activity of resulting gelatin as evidenced by the decreased surface tension and the increased foaming and emulsifying properties. Interaction between OLA and gelatin led to the generation of carbonyl groups, loss of free amino content and the increase in particle size of resulting gelatin. Emulsion stabilized by modified gelatin had the smaller mean particle diameter with higher stability, compared with that stabilized by gelatin without modification.

  4. Probing characteristics of collagen molecules on various surfaces via atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Su, Hao-Wei; Ho, Mon-Shu; Cheng, Chao-Min

    2012-06-01

    We examine, herein, specific dynamic responses of collagen molecules (i.e., observations of self-assembly and nanometric adhesion force measurements of type-I collagen molecules) as they interact with either a hydrophobic or a hydrophilic surface at two distinct temperatures, using a liquid-type atomic force microscope. We conclude that, regardless of surface hydrophobicity/hydrophilicity, assembled microfibrils eventually distribute homogeneously in accordance with changes in surface-related mechanical properties of collagen molecules at different self-assembly stages.

  5. Measurements of erosion characteristics for metal and polymer surfaces using profilometry

    NASA Technical Reports Server (NTRS)

    Christl, Ligia C.; Gregory, John C.; Peters, Palmer N.

    1992-01-01

    The surfaces of many materials exposed in low earth orbit are modified due to interaction with atomic oxygen. Chemical changes and surface roughening effects can occur which alter optical and other properties. The experiment A0114 contained 128 solid surface samples, half of which were exposed on the front and half on the rear of LDEF. Each sample has been subjected to many analyses, but only the methods and techniques used to measure the changes in roughness, erosion depths, and material growth using profilometry are described.

  6. Asymmetric spline surfaces - Characteristics and applications. [in high quality optical systems design

    NASA Technical Reports Server (NTRS)

    Stacy, J. E.

    1984-01-01