Influence of surface conductivity on the apparent zeta potential of calcite
Li, Shuai; Heberling, Frank; Devau, Nicolas; Jougnot, Damien; Chiaberge, Christophe
2016-01-01
Zeta potential is a physicochemical parameter of particular importance in describing the surface electrical properties of charged porous media. However, the zeta potential of calcite is still poorly known because of the difficulty to interpret streaming potential experiments. The Helmholtz-Smoluchowski (HS) equation is widely used to estimate the apparent zeta potential from these experiments. However, this equation neglects the influence of surface conductivity on streaming potential. We present streaming potential and electrical conductivity measurements on a calcite powder in contact with an aqueous NaCl electrolyte. Our streaming potential model corrects the apparent zeta potential of calcite by accounting for the influence of surface conductivity and flow regime. We show that the HS equation seriously underestimates the zeta potential of calcite, particularly when the electrolyte is diluted (ionic strength < 0.01 M) because of calcite surface conductivity. The basic Stern model successfully predicted ...
Influence of surface conductivity on the apparent zeta potential of calcite.
Li, Shuai; Leroy, Philippe; Heberling, Frank; Devau, Nicolas; Jougnot, Damien; Chiaberge, Christophe
2016-04-15
Zeta potential is a physicochemical parameter of particular importance in describing the surface electrical properties of charged porous media. However, the zeta potential of calcite is still poorly known because of the difficulty to interpret streaming potential experiments. The Helmholtz-Smoluchowski (HS) equation is widely used to estimate the apparent zeta potential from these experiments. However, this equation neglects the influence of surface conductivity on streaming potential. We present streaming potential and electrical conductivity measurements on a calcite powder in contact with an aqueous NaCl electrolyte. Our streaming potential model corrects the apparent zeta potential of calcite by accounting for the influence of surface conductivity and flow regime. We show that the HS equation seriously underestimates the zeta potential of calcite, particularly when the electrolyte is diluted (ionic strength ⩽ 0.01 M) because of calcite surface conductivity. The basic Stern model successfully predicted the corrected zeta potential by assuming that the zeta potential is located at the outer Helmholtz plane, i.e. without considering a stagnant diffuse layer at the calcite-water interface. The surface conductivity of calcite crystals was inferred from electrical conductivity measurements and computed using our basic Stern model. Surface conductivity was also successfully predicted by our surface complexation model.
Liu, Yanju; Naidu, Ravendra; Ming, Hui
2013-03-15
The surface electrochemical properties of red mud (bauxite residue) from different alumina refineries in Australia and China were studied by electrophoresis and measuring surface charge density obtained from acid/base potentiometric titrations. The electrophoretic properties were measured from zeta potentials obtained in the presence of 0.01 and 0.001 M KNO(3) over a wide pH range (3.5-10) by titration. The isoelectric point (IEP) values were found to vary from 6.35 to 8.70 for the red mud samples. Further investigation into the surface charge density of one sample (RRM) by acid/base potentiometric titration showed similar results for pH(PZC) with pH(IEP) obtained from electrokinetic measurements. The pH(IEP) determined from zeta potential measurements can be used as a characteristic property of red mud. The minerals contained in red mud contributed to the different values of pH(IEP) of samples obtained from different refineries. Different relationships of pH(IEP) with Al/Fe and Al/Si ratios (molar basis) were also found for different red mud samples.
Surface free energy components of glass from ellipsometry and zeta potential measurements
Chibowski, E.; Hołysz, L.; Kip, Gerhardus A.M.; van Silfhout, Arend; Busscher, H.J.
1989-01-01
Two different experimental approaches based on ellipsometry and zeta potential measurements have been employed to determine the dispersion and polar surface free energy components of glass. From ellipsometry the adsorption isotherms of n-octane and water have been determined, yielding values for the
Lopes, M A; Monteiro, F J; Santos, J D; Serro, A P; Saramago, B
1999-06-15
Wettability and zeta potential studies were performed to characterize the hydrophobicity, surface tension, and surface charge of P2O5-glass-reinforced hydroxyapatite composites. Quantitative phase analysis was performed by the Rietveld method using GSAS software applied to X-ray diffractograms. Surface charge was assessed by zeta potential measurements. Protein adsorption studies were performed using vitronectin. Contact angles and surface tensions variation with time were determined by the sessile and pendent drop techniques, respectively, using ADSA-P software. The highest (-18.1 mV) and lowest (-28.7 mV) values of zeta potential were found for hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP), respectively, with composite materials presenting values in between. All studied bioceramic materials showed similar solid surface tension. For HA and beta-TCP, solid surface tensions of 46.7 and 45.3 mJ/m2, respectively, were obtained, while composites presented intermediate surface tension values. The dispersive component of surface tension was the predominant one for all materials studied. Adhesion work values between the vitronectin solution and HA and beta-TCP were found to be 79.8 and 88.0 mJ/m2, respectively, while the 4.0 wt % glass composites showed slightly lower values than the 2.5 wt % ones. The presence of beta-TCP influenced surface charge, hydrophobicity, and protein adsorption of the glass-reinforced HA composites, and therefore indirectly affected cell-biomaterial interactions.
The Zeta Potential of Surface-Functionalized Metallic Nanorod Particles in Aqueous Solution
Energy Technology Data Exchange (ETDEWEB)
Dougherty, G M; Rose, K A; Tok, J B; Pannu, S S; Chuang, F S; Sha, M Y; Chakarova, G; Penn, S G
2007-05-07
Metallic nanoparticles suspended in aqueous solutions, and functionalized with chemical and biological surface coatings, are important elements in basic and applied nanoscience research. Many applications require an understanding of the electrokinetic or colloidal properties of such particles. In this paper we describe the results of experiments to measure the zeta potential of metallic nanorod particles in aqueous saline solutions, including the effects of pH, ionic strength, metallic composition, and surface functionalization state. Particle substrates tested include gold, silver, and palladium monometallic particles as well as gold/silver bimetallic particles. Surface functionalization conditions included 11-mercaptoundecanoic acid (MUA), mercaptoethanol (ME), and mercaptoethanesulfonic acid (MESA) self-assembled monolayers (SAMs), as well as MUA layers subsequently derivatized with proteins. Zeta potential data for typical charge-stabilized polystyrene particles are also presented for comparison. Experimental data are compared with theory. The results of these studies are useful in predicting and controlling the aggregation, adhesion, and transport of functionalized metallic nanoparticles within microfluidic devices and other systems.
Pinho, Ana C; Piedade, Ana P
2013-08-28
The sputtering deposition of gold (Au) and poly(tetrafluoroethylene) (PTFE) was used to prepare a nanocomposite hybrid thin film suitable for protein adsorption while maintaining the native conformation of the biological material. The monolithic PTFE and the nanocomposite PTFE/Au thin films, with Au content up to 1 at %, were co-deposited by r.f. magnetron sputtering using argon as a discharge gas and deposited onto 316L stainless steel substrates, the most commonly used steel in biomaterials. The deposited thin films, before and after bovine serum albumin (BSA) adsorption, were thoroughly characterized with special emphasis on the surface properties/characteristics by atomic force microscopy (AFM), zeta potential, and static and dynamic contact angle measurements, in order to assess the relationship between structure and conformational changes. The influence of a pre-adsorbed peptide (RGD) was also evaluated. The nanotopographic and chemical changes induced by the presence of gold in the nanocomposite thin films enable RGD bonding, which is critical for the maintenance of the BSA native conformation after adsorption.
Energy Technology Data Exchange (ETDEWEB)
Cherepy, N J; Shen, T H; Esposito, A P; Tillotson, T M
2004-06-02
We have developed a cleaning procedure for aluminum alloys for effective minimization of surface-adsorbed sub-micron particles and non-volatile residue. The procedure consists of a phosphoric acid etch followed by an alkaline detergent wash. To better understand the mechanism whereby this procedure reduces surface contaminants, we characterized the aluminum surface as a function of cleaning step using Surface Enhanced Raman Spectroscopy (SERS). SERS indicates that phosphoric acid etching re-establishes a surface oxide of different characteristics, including deposition of phosphate and increased hydration, while the subsequent alkaline detergent wash appears to remove the phosphate and modify the new surface oxide, possibly leading to a more compact surface oxide. We also studied the zeta potential of <5 micron pure aluminum and aluminum alloy 6061-T6 particles to determine how surface electrostatics may be affected during the cleaning process. The particles show a decrease in the magnitude of their zeta potential in the presence of detergent, and this effect is most pronounced for particles that have been etched with phosphoric acid. This reduction in magnitude of the surface attractive potential is in agreement with our observation that the phosphoric acid etch followed by detergent wash results in a decrease in surface-adsorbed sub-micron particulates.
Kinraide; Yermiyahu; Rytwo
1998-10-01
A Gouy-Chapman-Stern model has been developed for the computation of surface electrical potential (psi0) of plant cell membranes in response to ionic solutes. The present model is a modification of an earlier version developed to compute the sorption of ions by wheat (Triticum aestivum L. cv Scout 66) root plasma membranes. A single set of model parameters generates values for psi0 that correlate highly with published zeta potentials of protoplasts and plasma membrane vesicles from diverse plant sources. The model assumes ion binding to a negatively charged site (R- = 0.3074 &mgr;mol m-2) and to a neutral site (P0 = 2.4 &mgr;mol m-2) according to the reactions R- + IZ &rlharr; RIZ-1 and P0 + IZ &rlharr; PIZ, where IZ represents an ion of charge Z. Binding constants for the negative site are 21, 500 M-1 for H+, 20,000 M-1 for Al3+, 2,200 M-1 for La3+, 30 M-1 for Ca2+ and Mg2+, and 1 M-1 for Na+ and K+. Binding constants for the neutral site are 1/180 the value for binding to the negative site. Ion activities at the membrane surface, computed on the basis of psi0, appear to determine many aspects of plant-mineral interactions, including mineral nutrition and the induction and alleviation of mineral toxicities, according to previous and ongoing studies. A computer program with instructions for the computation of psi0, ion binding, ion concentrations, and ion activities at membrane surfaces may be requested from the authors.
Energy Technology Data Exchange (ETDEWEB)
Hilda Parra-Barraza; Daniel Hernandez-Montiel; Jaime Lizardi; Javier Hernandez; Ronaldo Herrera Urbina; Miguel A. Valdez [Universidad de Sonora, Sonora (Mexico). Departamento de Ciencias Quimico Biologicas
2003-05-01
We have investigated some surface properties of asphaltenes precipitated from crude oil with different volumes of n-heptane. According to the crude oil/n-heptane proportions used, asphaltenes are identified as 1:5, 1:15 and 1:40. Zeta potential results indicate that the amount of n-heptane determines the electrokinetic behaviour of asphaltenes in aqueous suspensions. Asphaltene 1:5 exhibits an isoelectric point (IEP) at pH 4.5 whereas asphaltenes 1:15 and 1:40 show an IEP at about pH 3. Surface charge on asphaltenes arises from the dissociation of acid functionalities and the protonation of basic functional groups. The presence of resins remaining on the asphaltene molecules may be responsible for the different IEP of asphaltene 1:5. Both sodium dodecyl sulfate (an anionic surfactant) and cetylpyridinium chloride (a cationic surfactant) were found to adsorb specifically onto asphaltenes. They reverse the sign of the zeta potential under certain conditions. These surfactants may be potential candidates to aid in controlling the stability of crude oil dispersions. Critical micelle concentration, interfacial tension measurements, and Langmuir isotherms at the air water interface confirm the different nature of asphaltene 1:5, which also showed more solubility and a larger molecular size. 26 refs., 3 figs., 1 tab.
Sun, Peiling; Horton, J. Hugh
2013-04-01
Poly(dimethylsiloxane) (PDMS) is a widely-used polymer in microfluidic devices due to its range of physical and chemical properties suitable for molding micron-sized features. However, its hydrophobicity also leads to some limitations: it poorly supports electro-osmotic flow, and can be incompatible with biomolecules and with many organic solvents. Surface modification is commonly used to vary PDMS surface properties to make it more suitable for specific microfluidic applications. Here, we report on the surface modification of PDMS using perfluoroalkane-triethoxysilanes, via the covalent attachment of triethoxysilane groups on plasma-oxidized PDMS. A device constructed from such fluorinated materials could be used for separating fluorous-tagged proteins or peptides. Modified PDMS were characterized using a range of surface analytical methods. In particular, zeta- (ζ-) potential values at the interfaces of both modified and unmodified PDMS and under varying pH conditions were measured, as ζ-potential is an essential parameter to support electroosmotic flow (EOF), a common pumping method in microfluidic devices. The results showed the length of fluorinated alkane chain has significant effect on the density of surface modifying species and topography following modification. In addition, the perfluorinated modification increases the magnitude of the ζ-potential at the PDMS interface when compared to that of native PDMS, increasing the electro-osmotic flow rate, over a wide pH range. The modified surface is resistant to the diffusion of PDMS oligomers that affects other PDMS surface modification processes.
Wettability Studies Using Zeta Potential Measurements
Directory of Open Access Journals (Sweden)
Ghada Bassioni
2015-01-01
Full Text Available Wettability studies have been carried out on reservoir rocks using different techniques such as the Amott-Harvey method, the USBM method, and the contact angle method, all with limitations. In this study, the wettability is studied by discussing the surface charge using zeta potential measurements. The study relies on the finding that carbonated reservoir rocks, consisting of CaCO3 mainly, are positively charged and their surface has the potential to adsorb significant quantities of anions. Moreover, heavy fractions such as asphaltenes are reported to remain afloat depending on dispersive forces present in the oil and its various fractions. Experiments are carried out on aqueous limestone suspension with the addition of crude oil. The experiment is repeated with the use of polymeric inhibitors, A and B. The zeta potential is found to alter depending on the sequence of polymeric inhibitor in oil/water addition. The inhibitor is found to adsorb on the limestone surface, with a net negative charge, causing repulsion between crude oil and the inhibitor and, hence, preventing the deposition of heavy fractions and particularly asphaltenes. This study gives a comprehensive insight on the mechanism of polymeric inhibitor interaction with the surface and the effect of wettability on its performance.
Energy Technology Data Exchange (ETDEWEB)
Kuenzelmann, U.; Reinhard, G. (Technische Univ., Dresden (German Democratic Republic). Sektion Chemie); Jacobasch, H.J. (Akademie der Wissenschaften der DDR, Dresden. Inst. fuer Technologie der Fasern (German Democratic Republic))
1989-12-01
Adsorbability of the vapour phase inhibitor dicyclohexylammonium nitrite (Dichan) and its ionic constituents present in aqueous media were investigated by means of zeta-potential measurements in 10{sup -3} M KCl solution in dependence on the pH-value using particles of various iron oxides and oxide hydroxides. It was pointed out, that the interactions between Dichan and iron oxides result in a negativation of the zeta-potential and in a displacement of the isoelectric point of the particles surface (IEPS) due to specific adsorption of anions. By dicyclohexylamine in the primary solution, the zeta-potential of iron oxides is hardly influenced, even when the saturation concentration is established. As nitrite changes the chemical surface properties when concentrations considerably higher than those indicated for Dichan are achieved, a synergism is assumed to be present because of the Dichan's high adsorbability at oxidic iron compounds. This effect probable consist in the promotion of the specific adsorption of nitrite ions at the oxide surface by the amine component. (orig.).
Zeta potential of microfluidic substrates: 2. Data for polymers.
Kirby, Brian J; Hasselbrink, Ernest F
2004-01-01
Zeta potential data are reviewed for a variety of polymeric microfluidic substrate materials. Many of these materials currently used for microchip fabrication have only recently been employed for generation of electroosmotic flow. Despite their recent history, polymeric microfluidic substrates are currently used extensively for microchip separations and other techniques, and understanding of the surface zeta potential is crucial for experimental design. This paper proposes the use of pC (the negative logarithm of the counterion concentration) as a useful normalization for the zeta potential on polymer substrates in contact with indifferent univalent counterions. Normalizing zeta by pC facilitates comparison of results from many investigators. The sparseness of available data for polymeric substrates prevents complete and rigorous justification for this normalization; however, it is consistent with double layer and adsorption theory. For buffers with indifferent univalent cations, normalization with the logarithm of the counterion concentration in general collapses data onto a single zeta/pC vs. pH curve, and (with the exception of PMMA) the repeatability of the data is quite encouraging. Normalization techniques should allow improved ability to predict zeta potential performance on microfluidic substrates and compare results observed with different parameters.
Zeta-potential of fouled thin film composite membrane
Energy Technology Data Exchange (ETDEWEB)
Ikeda, K.; Hachisuka, H.; Nakamura, T. [Nitto denko Corp., Ibaraki, (Japan); Kimura, S. [Kogakuin University, Tokyo (Japan). Dept. of Environ. Chemical Engineering; Ueyama, K. [Osaka University, Osaka (Japan). Dept. of Chemical Engineering
1999-10-01
The surface zeta-potential of a cross-linked polyamide thin film composite reverse osmosis membrane was measured using an electrophoresis method. It was confirmed that this method could be effectively applied to analyze the fouling of such membranes. It is known that the water flux of membranes drastically decreases as a result of fouling by surfactants. Although the surfactants adsorbed on reverse osmosis membranes could not be detected by conventional methods such as SEM, EDX and FT-IR, their presence could be clarified by the profile measurements of the surface zeta-potential. The profiles of the membrane surface zeta-potentials changed to more positive values in the measured pH range as a result of fouling by cationic or amphoteric surfactants. This measuring method of surface zeta-potentials allowed us to analyze a very small amount of fouling of a thin film composite reverse osmosis membrane. This method could be used to analyze the fouled surface of the thin film composite reverse osmosis membrane which is used for production of ultrapure water and shows a remarkable decrease in flux. It also became clear that this method is easy and effective for the reverse osmosis membrane surface analysis of adsorbed materials such as surfactants. (author)
A study on the zeta potential of microcapsules during ageing.
Labhasetwar, V D; Dorle, A K
1991-01-01
Gelatin, methylcellulose and agar microcapsules were prepared with and without suphadiazine. The zeta potential of these microcapsules was measured at regular intervals during ageing at 45 degrees C. An initial sharp rise in zeta potential is followed by a progressive decrease. Zeta potential could prove to be a useful parameter to study the changes occurring in the encapsulating material of microcapsules during ageing.
Energy Technology Data Exchange (ETDEWEB)
Grover, Inderpreet Singh; Singh, Satnam; Pal, Bonamali, E-mail: bpal@thapar.edu
2013-09-01
Titania based nanocatalysts such as sodium titanates of different morphology having superior surface properties are getting wide importance in photocatalysis research. Despite having sodium (Na) contents and its high temperature synthesis (that generally deteriorate the photoreactivity), these Na-titanates often exhibit better photoactivity than P25-TiO{sub 2} catalyst. Hence, this work demonstrated the influence of crystal structure, BET surface area, surface charge, zeta potential (ζ) and metal loading on the photocatalytic activity of as-prepared sodium titanate nanotube (TNT) and titania nanorod (TNR). Straw like hollow orthorhombic-TNT (Na{sub 2}Ti{sub 2}O{sub 5}·H{sub 2}O) particles (W = 9–12 nm and L = 82–115 nm) and rice like pure anatase-TNR particles (W = 8–13 nm and L = 81–134 nm) are obtained by the hydrothermal treatment of P25-TiO{sub 2} with NaOH, which in fact, altered the net surface charge of TNT and TNR particles. The observed ζ = −2.82 (P25-TiO{sub 2}), −13.5 (TNT) and −22.5 mV (TNR) are significantly altered by the Ag and Cu deposition. It has been found here that TNT displayed best photocatalytic activity for the imidacloprid insecticide (C{sub 9}H{sub 10}ClN{sub 5}O{sub 2}) degradation to CO{sub 2} formation under UV irradiation because of its largest surface area 176 m{sup 2} g{sup −1} among the catalysts studied.
Zeta potential in colloid science principles and applications
Hunter, Robert J; Rowell, R L
2013-01-01
Zeta Potential in Colloid Science: Principles and Applications covers the concept of the zeta potential in colloid chemical theory. The book discusses the charge and potential distribution at interfaces; the calculation of the zeta potential; and the experimental techniques used in the measurement of electrokinetic parameters. The text also describes the electroviscous and viscoelectric effects; applications of the zeta potential to areas of colloid science; and the influence of simple inorganic ions or more complex adsorbates on zeta potential. Physical chemists and people involved in the stu
Zeta-function approach to Casimir energy with singular potentials
Khusnutdinov, N R
2006-01-01
In the framework of zeta-function approach the Casimir energy for three simple model system: single delta potential, step function potential and three delta potentials is analyzed. It is shown that the energy contains contributions which are peculiar to the potentials. It is suggested to renormalize the energy using the condition that the energy of infinitely separated potentials is zero which corresponds to subtraction all terms of asymptotic expansion of zeta-function. The energy obtained in this way obeys all physically reasonable conditions. It is finite in the Dirichlet limit and it may be attractive or repulsive depending on the strength of potential. The effective action is calculated and it is shown that the surface contribution appears. The renormalization of the effective action is discussed.
BUSSCHER, HJ; VANDEBELTGRITTER, B; VANDERMEI, HC
1995-01-01
Microbial adhesion to hydrocarbons (MATH) is generally considered to be a measure of the organisms cell surface hydrophobicity. As microbial adhesion is a complicated interplay of long-range van der Waals and electrostatic forces and various short-range interactions, the above statement only holds
Zeta potential of mica covered by colloid particles: a streaming potential study.
Adamczyk, Zbigniew; Zaucha, Maria; Zembala, Maria
2010-06-15
The streaming potential of mica covered by monodisperse latex particles was measured using the parallel-plate channel, four-electrode cell. The zeta potential of latex bearing amidine charged groups was regulated by the addition of NaCl (10(-4)-10(-2) M) and MgCl(2) (10(-4)-10(-2) M) at a constant pH 5.5 and by the change in pH (4-12) at 10(-2) M NaCl. The size of the latex particles, determined by dynamic light scattering, varied between 502 and 540 nm for the above electrolyte concentration range. Mica sheets have been covered with latex particles under diffusion transport conditions. The latex coverage was regulated by the bulk suspension concentration in the channel and the deposition time. The coverage was determined, with a relative precision of 2%, by the direct enumeration of particles by optical microscopy and AFM. The streaming potential of mica was then determined for a broad range of particle coverage 0 < theta < 0.5, the particle-to-substrate zeta potential ratio zeta(p)/zeta(i), and 8.8 < kappa a < 143 (thin double-layer limit). These experimental data confirmed that the streaming potential of covered surfaces is well reflected by the theoretical approach formulated in ref 32. It was also shown experimentally that variations in the substrate streaming potential with particle coverage for theta < 0.3 and zeta(p)/zeta(i) < 0 are characterized by a large slope, which enables the precise detection of particles attached to interfaces. However, measurements at high coverage and various pH values revealed that the apparent zeta potential of covered surfaces is 1/2(1/2) smaller than the bulk zeta potential of particles (in absolute terms). This is valid for arbitrary zeta potentials of substrates and particles, including the case of negative particles on negatively charged substrates that mimics rough surfaces. Therefore, it was concluded that the streaming potential method can serve as an efficient tool for determining bulk zeta potentials of colloids and
Generation of directional EOF by interactive oscillatory zeta potential.
Kuo, Chih-Yu; Wang, Chang-Yi; Chang, Chien-Cheng
2008-11-01
A steady directional EOF due to a nonlinear interaction between oscillatory axial electrical fields and oscillatory wall potentials (zeta potentials) is presented. This is a new mechanism to produce such a mean flow. It is found that the flow velocity depends not on the external driving frequency but on the phase angle difference between the electric fields and the zeta potentials. The formulation can also be reduced to the static EOF straightforwardly. For the purpose of theoretical demonstration, we use the Debye-Huckel approximation for the zeta potential. Results of planar and cylindrical capillaries are given.
A study on zeta potential and dielectric constant of liposomes.
Labhasetwar, V; Mohan, M S; Dorle, A K
1994-01-01
Zeta potential and dielectric constant of the liposomes were measured to study the effect of some of the formulation factors and in vitro ageing. Sonication affects zeta potential and dielectric constant of the liposomes. The ageing study showed an increase in the dielectric constant and zeta potential of liposomes at different storage temperatures. These two electrical parameters could be useful in studying structural alterations in liposomal vesicles and system as a function of different conditions. Particle size distribution and optical density were also measured, for comparison.
Zeta Potential and Rheological Behavior of ULC Castables Matrix
Institute of Scientific and Technical Information of China (English)
XU Yuanchao; WANG Zhanmin; CAO Xiying
2008-01-01
Effects of starting materials and four dispersants (STP, SHP, FDN and FS60) on Zeta potential and rheological behavior of alumina based ULC castables matrix were investigated. The results show that: characteristics of silica fume and alumina cements play a very important role in Zeta potential and viscosity of suspensions of the castables matrix; the dispersants STP and SHP can change Zeta potential values of the matrix suspensions remarkably; the four dispersants can effectively improve the rheological properties of matrix suspensions. For the point of lower viscosity of the matrix suspensions, the suitable additions of the three dispersants (SHP, FDN and FS60) are about 0.2% while that of STP is about 0.3%.
Zeta potential change of Neuro-2a tumor cells after exposure to alumina nanoparticles
Kazantsev, Sergey O.; Fomenko, Alla N.; Korovin, Matvey S.
2016-08-01
In recent years, researches have paid much attention to the physical, chemical, biophysical and biochemical properties of a cell surface. It is known that most of the cells' surfaces are charged. This charge depends on the biochemical structure of the cell membranes. Therefore, measurement of a cell surface charge is a significant criterion that gives information about the cell surface. Evaluation of the cells zeta-potential is important to understand the interaction mechanisms of various drugs, antibiotics, as well as the interaction of nanoparticles with the cell surface. In this study, we use the dynamic light scattering method to detect the zeta-potential change of Neuro-2a tumor cells. It has been observed that zeta-potential shifted to negative values after exposure to metal oxide nanoparticles and inducing apoptosis.
Zeta potentials in the flotation of oxide and silicate minerals.
Fuerstenau, D W; Pradip
2005-06-30
Adsorption of collectors and modifying reagents in the flotation of oxide and silicate minerals is controlled by the electrical double layer at the mineral-water interface. In systems where the collector is physically adsorbed, flotation with anionic or cationic collectors depends on the mineral surface being charged oppositely. Adjusting the pH of the system can enhance or prevent the flotation of a mineral. Thus, the point of zero charge (PZC) of the mineral is the most important property of a mineral in such systems. The length of the hydrocarbon chain of the collector is important because of chain-chain association enhances the adsorption once the surfactant ions aggregate to form hemimicelles at the surface. Strongly chemisorbing collectors are able to induce flotation even when collector and the mineral surface are charged similarly, but raising the pH sufficiently above the PZC can repel chemisorbing collectors from the mineral surface. Zeta potentials can be used to delineate interfacial phenomena in these various systems.
Optical tweezers as a new biomedical tool to measure zeta potential of stored red blood cells.
Directory of Open Access Journals (Sweden)
Diego C N Silva
Full Text Available During storage, red blood cells (RBCs for transfusion purposes suffer progressive deterioration. Sialylated glycoproteins of the RBC membrane are responsible for a negatively charged surface which creates a repulsive electrical zeta potential. These charges help prevent the interaction between RBCs and other cells, and especially among each RBCs. Reports in the literature have stated that RBCs sialylated glycoproteins can be sensitive to enzymes released by leukocyte degranulation. Thus, the aim of this study was, by using an optical tweezers as a biomedical tool, to measure the zeta potential in standard RBCs units and in leukocyte reduced RBC units (collected in CPD-SAGM during storage. Optical tweezers is a sensitive tool that uses light for measuring cell biophysical properties which are important for clinical and research purposes. This is the first study to analyze RBCs membrane charges during storage. In addition, we herein also measured the elasticity of RBCs also collected in CPD-SAGM. In conclusion, the zeta potential decreased 42% and cells were 134% less deformable at the end of storage. The zeta potential from leukodepleted units had a similar profile when compared to units stored without leukoreduction, indicating that leukocyte lyses were not responsible for the zeta potential decay. Flow cytometry measurements of reactive oxygen species suggested that this decay is due to membrane oxidative damages. These results show that measurements of zeta potentials provide new insights about RBCs storage lesion for transfusion purposes.
Kabat's Surface Terms in the $\\zeta$-Function approach
Iellici, D; Iellici, Devis; Moretti, Valter
1997-01-01
The thermal partition functions of photons in any covariant gauge and gravitons in the harmonic gauge, propagating in a Rindler wedge, are computed using a local zeta-function approach. The relation with the surface terms previously obtained by D. Kabat is studied. The results are discussed in relation to the quantum corrections to the black hole entropy.
Kabat's Surface Terms in the Zeta-Function Approach
Iellici, D.; Moretti, V.
The thermal partition functions of photons in any covariant gauge and gravitons in the harmonic gauge, propagating in a Rindler wedge, are computed using a local zeta-function approach. The relation with the surface terms previously obtained by D. Kabat is studied. The results are discussed in relation to the quantum corrections to the black hole entropy.
Energy Technology Data Exchange (ETDEWEB)
Jayaweera, P.; Hettiarachchi, S.; Pound, B.G. (SRI International, Menlo Park, CA (United States))
1992-10-01
This report describes the results of research to determine the zeta potential of oxides responsible for fouling of heat transfer, venturi, and other flow measurement device surfaces. Fouling deposits formed on these surfaces reduce mass flow rates of water, causing power reductions of as much as 3 to 4%. There is considerable evidence that deposit formation can be prevented by coating the critical surfaces with a coating material that electrostatically repels the suspended fouling particulates. The zeta potential can be used as a parameter to identify and determine the best coating material to be employed for fouling prevention. The research entailed the development of the equipment necessary for zeta potential measurements, measurement of zeta potentials of oxides and coatings of interest to nuclear power plant applications, and evaluation of candidate coating materials to prevent fouling of surfaces. By this approach, numerous metals and oxides have been identified as potential coating materials. Fouling studies revealed that magnetite does not deposit on tungsten and palladium surfaces, indicating the potential use of these metals for coating venturi surfaces used in nuclear power plants.
Transient zeta-potential measurements in hydrophobic, TOPAS microfluidic substrates.
Tandon, Vishal; Bhagavatula, Sharath K; Kirby, Brian J
2009-08-01
We utilize time-resolved electrokinetic measurements in order to study the electrokinetic properties of silica and TOPAS microfluidic channels as a function of the time history of the fluid-solid interface. In pressure-driven flow through TOPAS microchannels, the zeta-potential as inferred from streaming potential measurements decays exponentially by a factor of 1.5 with a characteristic decay time of 3 h after the initial formation of the fluid-solid interface. A similar exponential decay is observed immediately after water is exchanged for ethanol as the solvent in the system. In electroosmotically driven flow through TOPAS microchannels, the zeta-potential as inferred through current monitoring experiments was constant in time. No electrokinetic transients were observed in silica microchannels under these flow conditions.
EFFECTS OF PROCESSING OPERATIONS ON ZETA POTENTIAL AND CATIONIC DEMAND OF PULPS
Institute of Scientific and Technical Information of China (English)
Nishi K. Bhardwaj; Sanjay Kumar; Pramod K. Bajpai
2004-01-01
Thc zeta potential and cationic demands of various kraft pulps - unbleached, bleached and beaten to different freeness levels were determined in the laboratory. The zeta potential of pulp where the final stage was a lignin degrading and dissolving treatment such as alkaline extraction or hypochlorite was lower than the unbleached pulp. The cationic demand of unbleached pulp was higher compared to that of bleached pulp. Beaten pulps showed larger cationic demands than the unbeaten pulps, which can be attributed to the larger specific surface area of pulp components. Fibres become increasingly electronegative when beaten and therefore cationic demand of pulps increases with beating. When the zeta potential method is used with furnishes of different freeness,the linear relationship is observed. However, the slope is decreasing with the decrease in freeness of the pulp.
Wouden, van der E.J.; Hermes, D.C.; Gardeniers, J.G.E.; Berg, van den A.
2006-01-01
Electroosmotic flow (EOF) in a microchannel can be controlled by electronic control of the surface charge using an electrode embedded in the wall of the channel. By setting a voltage to the electrode, the zeta-potential at the wall can be changed locally. Thus, the electrode acts as a "gate" for liq
Electroviscous effect on fluid drag in a microchannel with large zeta potential.
Jing, Dalei; Bhushan, Bharat
2015-01-01
The electroviscous effect has been widely studied to investigate the effect of surface charge-induced electric double layers (EDL) on the pressure-driven flow in a micro/nano channel. EDL has been reported to reduce the velocity of fluid flow and increase the fluid drag. Nevertheless, the study on the combined effect of EDL with large zeta potential up to several hundred millivolts and surface charge depenedent-slip on the micro/nano flow is still needed. In this paper, the nonlinear Poisson-Boltzmann equation for electrical potential and ion distribution in non-overlapping EDL is first analytically solved. Then, the modified Navier-Stokes equation for the flow considering the effect of surface charge on the electrical conductivity of the electrolyte and slip length is analytically solved. This analysis is used to study the effect of non-overlapping EDL with large zeta potential on the pressure-driven flow in a microchannel with no-slip and charge-dependent slip conditions. The results show that the EDL leads to an increase in the fluid drag, but that slip can reduce the fluid drag. When the zeta potential is large enough, the electroviscous effect disappears for flow in the microchannel under a no-slip condition. However, the retardation of EDL on the flow and the enhancement of slip on the flow counteract each other under a slip condition. The underlying mechanisms of the effect of EDL with large zeta potential on fluid drag are the high net ionic concentration near the channel wall and the fast decay of electrical potential in the EDL when the zeta potential is large enough.
Measuring zeta potential of protein nano-particles using electroacoustics.
Dukhin, A S; Parlia, S
2014-09-01
Electroacoustic spectroscopy offers a simple way for measuring the zeta potential of proteins in physiological solutions with high ionic strength. Ultrasound as a driving force does not generate the heat effects which complicate traditional electrophoretic measurements at high ionic strength. In addition, measurements can be conducted with concentrated protein dispersions without dilution, as is required by electrophoretic methods. This paper presents results for electroacoustic measurements of 5wt.% bovine serum albumin suspended in aqueous solutions. In these suspensions the proteins are not completely dissolved; they form nano-particles with a median size of about 180nm. We studied the dependence of zeta potential on ionic strength within a wide range of salt molarities, up to as high as 0.5mol/L. Dialysis was used for performing measurements at lower ionic strength range. We also conducted pH titrations of this system and titrations with Ca(2+) ions. Our results agree well with published data for samples where such data is available.
Measuring the zeta potential. The relationships with sandstone fineness
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de Luxán, M. P.
1989-09-01
Full Text Available The application of the zeta potential technique in the area of construction materials and Portland cement is quite recent. The initial research work involved the study of cement suspensions or suspensions of one of the components of cement, such as alite, tricalcium alumínate, in the presence of additives and, more specifically, superplasticizers. The studies of this sort were extended with the mixing of active additions into cement (fly ashes, etc.. The present study discusses the application of siliceous materials (sandstone as a basis of the research into the behaviour of sandstone mortars containing repair products.
La aplicación de la técnica del potencial zeta en el campo de los materiales de construcción y del cemento portland es muy reciente. Las primeras investigaciones se refieren al estudio de suspensiones de cemento o de alguno de sus compuestos que lo forman como alita, aluminato tricálcico, en presencia de aditivos y, más concretamente, de superfluidificantes. Con la incorporación de adiciones activas al cemento (cenizas volantes,... se amplían los estudios de este tipo de cementos. En este trabajo se considera la aplicación a los materiales silíceos (arenisca como base para la investigación del comportamiento de los morteros de arenisca conteniendo productos de reparación.
Raw Coal Density Affected to Surface Zeta Potential of Muddy and Slime Particle%原煤密度对泥化及煤泥颗粒表面ξ电位的影响
Institute of Scientific and Technical Information of China (English)
赵晴; 闵凡飞; 刘令云; 李宏亮
2011-01-01
The muddy experiment on 50 -0.5 mm different density raw coal from Dingji Coal Preparation Plant of Huainan Mining Area was conducted. The X-ray diffractor and the electrophoresis experiment was individually applied to measure the raw coal mineral composition and the zeta potential on the micro particle surface of the slime. The results showed that the main mineral composition of the raw coal to be prepared would be including quartz, kaolinite, green mudstone and others. The muddy rate of the high density and medium density raw coal was high. In the muddy slime of the +1. 60 g/cmJ raw coal, the -0. 045 mm particles would be the majority and the -0. 025 mm micro particles would be over 90%. With the raw coal density increased and the slime particle reduced, the zeta potential on the micro particle surface of the muddy slime would be reduced in potential. The water hardness, the soluble salt in the raw coal and the particle surface property would have important influence to the zeta potential occurred on the slime micro particle. The zeta potential increased on the slime micro particle surface would cause the particles in the slime water in more stable dispersed state.%对淮南矿区丁集选煤厂50～0.5 mm不同密度级原煤进行了泥化试验,采用X-射线衍射 仪和电泳试验分别对原煤矿物组成和煤泥微细颗粒表面ξ电位进行了测定.结果表明:入选原煤中主要矿物成分有石英、高岭石、绿泥石等;高密度和中间密度级原煤泥化率大,+1.60g/cm3原煤泥化煤泥中-0.045 mm颗粒最多,其中约90%以上为-0.025 mm的微细颗粒;随着原煤密度的增大和煤泥粒度的减小,泥化煤泥微细颗粒表面ξ电位呈减小趋势,水的硬度、原煤中可溶性盐及颗粒表面性质对煤泥微细颗粒ξ电位产生重要影响,微细煤泥颗粒表面ξ电位增大会导致其在煤泥水中处于更加稳定的分散状态.
de la Cruz, EF; Zheng, Y.; Torres, E; Li, W.; Song, W; Burugapalli, K
2012-01-01
The main objective of this study is investigate the behavior of the Zeta Potential of the MWCNT modified with SDS(Sodium Dodecyl Sulfate) and CTAB(Cetyl Tetraethyl Ammonium Bromide) in presence of PVA. Full hydrolyzed PVA was used. As a result, adding PVA in the CNT solution led to decrease the Zeta Potential. The Zeta Potential of suspended colloid varied from 42.00mV to 6.48mV and -45.00mV to -6.4mV at 1.5% concentration of PVA; according with the changing pH, the Zeta Potential dropped to ...
Silver ion impregnated composite biomaterial optimally prepared using zeta potential measurements.
Sakthivel, N; Socrates, R; Shanthini, G M; Rajaram, A; Kalkura, S Narayana
2015-02-01
Biodegradable, antimicrobial composite of various silver ion concentrations was synthesized using zeta potential and isoelectric point measurements, for a controlled release of silver ions, and in addition to assess the effect of protein adsorption with the increase of the silver ion concentration. The interaction between hydroxyapatite (HAp) and silver incorporated hydroxyapatite (AgHAp) with gelatin was increased by optimally adjusting the zeta potential and isoelectric point of the ceramic (HAp and AgHAp), and bio-polymer individually. The electrostatic interactions between the ceramic and biopolymer were confirmed, through shifts in N-H stretching, decrease in the swelling ratio, and increase in the degradation temperature observed by the derivative thermo-gravimetric analysis (DTG). These results substantiate that, the zeta potential is a novel tool to increase the ceramic-biopolymer interaction. Increasing electrostatic interaction between the biopolymer and ceramic, decreases the release of silver ions in the simulated body fluid, due to the controlled degradation of the biopolymer. The isoelectric point decreases with the increase of the silver ion concentration, which evidenced the change in the net surface charge. With the increase of the silver ion concentration, the protein adsorption decreases due to an increase in hydrophilic character of the composite. This study examines the minimum concentration of silver ion essential for maximum protein adsorption, antimicrobial and hemocompatibility. This study provides a novel route to control the release of silver ions by enhancing the ceramic-polymer interaction and estimate the silver ion concentration suitable for protein adsorption. The prepared composite is nontoxic, degradable, and antimicrobial, with the controlled release of silver ions in the simulated body fluid.
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Gildas K. Gbassi
2014-07-01
Full Text Available Starch powders from two cultivars of Dioscorea rotundata (DR were analysed on the physicochemical aspect. Granulometric structure, zeta potential and differential scanning calorimetry of starch powders showed the following properties. Various shapes with predominance of granule ranging from 10 to 40 μm were noted. The zeta potential of DR went from positive values to negative values as the pH was increasing from 2 to 8. From pH 2 to 4, the zeta potential was positive. A significant difference was obtained between each value (p > 0.05. The zeta potential took a negative value from pH 5 and above. The results of thermal analysis show that starches start swelling at 68.91.5 C. Enthalpy of gelatinization was about 15 J.g-1 .
Physical properties of nanofluid suspension of ferromagnetic graphite with high Zeta potential
Souza, N. S.; Rodrigues, A. D.; Cardoso, C. A.; Pardo, H.; Faccio, R.; Mombru, A. W.; Galzerani, J. C.; de Lima, O. F.; Sergeenkov, S.; Araujo-Moreira, F. M.
2012-01-01
We report on the magnetic properties and stability of nanofluid ferromagnetic graphite (NFMG) studied through the measurements of its magnetization hysteresis curves, Raman spectrum and the so-called Zeta potential. The obtained results suggest a robust ferromagnetic behavior of NFMG even at room temperature along with a good stability of the dispersed solution (with Zeta potential around 41.3 mV) and a good reactivity between magnetic graphite and CTAB type cationic surfactant.
Arias, José L; López-Viota, Margarita; Clares, Beatriz; Ruiz, Ma Adolfina
2008-08-07
In this paper we have carried out a detailed investigation of the stability and redispersibility characteristics of fenbendazole aqueous suspensions, through a thermodynamic and electrokinetic characterization, considering the effect of both pH and ionic strength. The hydrophobic character of the drug, and the surface charge and electrical double-layer thickness play an essential role in the stability of the system, hence the need for a full characterization of fenbendazole. It was found that the drug suspensions displays "delayed" or "hindered" sedimentation, determined by their hydrophobic character and their low zeta potential (indicating a small electrokinetic charge on the particles). The electrostatic repulsion between the particles is responsible for the low sedimentation volume and poor redispersibility of the drug. However, only low concentrations of AlCl(3) induced a significant effect on both the zeta potential and stability of the drug, leading to a "free-layered" sedimentation and a very easy redispersion which could be of great interest in the design of an oral pharmaceutical dosage form for veterinary.
Morini, M A; Sierra, M B; Pedroni, V I; Alarcon, L M; Appignanesi, G A; Disalvo, E A
2015-07-01
The purpose of the work is to compare the influence of the multilamellarity, phase state, lipid head groups and ionic media on the origin of the surface potential of lipid membranes. With this aim, we present a new analysis of the zeta potential of multilamellar and unilamellar vesicles composed by phosphatidylcholines (PC) and phosphatidylethanolamines (PE) dispersed in water and ionic solutions of polarizable anions, at temperatures below and above the phase transition. In general, the adsorption of anions seems to explain the origin of the zeta potential in vesicles only above the transition temperature (Tc). In this case, the sign of the surface potential is ascribed to a partial orientation of head group moiety toward the aqueous phase. This is noticeable in PC head groups but not in PEs, due to the strong lateral interaction between PO and NH group in PE.
Wyrzykowska, Ewelina; Mikolajczyk, Alicja; Sikorska, Celina; Puzyn, Tomasz
2016-11-01
Once released into the aquatic environment, nanoparticles (NPs) are expected to interact (e.g. dissolve, agglomerate/aggregate, settle), with important consequences for NP fate and toxicity. A clear understanding of how internal and environmental factors influence the NP toxicity and fate in the environment is still in its infancy. In this study, a quantitative structure-property relationship (QSPR) approach was employed to systematically explore factors that affect surface charge (zeta potential) under environmentally realistic conditions. The nano-QSPR model developed with multiple linear regression (MLR) was characterized by high robustness ({{{Q}}{{2}}}{{CV}}=0.90) and external predictivity ({{{Q}}{{2}}}{{EXT}}=0.93). The results clearly showed that zeta potential values varied markedly as functions of the ionic radius of the metal atom in the metal oxides, confirming that agglomeration and the extent of release of free MexOy largely depend on their intrinsic properties. A developed nano-QSPR model was successfully applied to predict zeta potential in an ionized solution of NPs for which experimentally determined values of response have been unavailable. Hence, the application of our model is possible when the values of zeta potential in the ionized solution for metal oxide nanoparticles are undetermined, without the necessity of performing more time consuming and expensive experiments. We believe that our studies will be helpful in predicting the conditions under which MexOy is likely to become problematic for the environment and human health.
Measuring microchannel electroosmotic mobility and zeta potential by the current monitoring method.
Shao, Chenren; Devoe, Don L
2013-01-01
Electroosmotic flow (EOF) is an electrokinetic flow control technique widely used in microfluidic systems for applications including direct electrokinetic pumping, hydrodynamic pressure generation, and counterflow for microfluidic separations. During EOF, an electric field is applied along the length of a microchannel containing an electrolyte, with mobile ions near the charged microchannel walls experiencing a Coulomb force due to electrostatic interactions with the applied electric field that leads to bulk solution movement. The goal of this laboratory is to experimentally determine the fixed channel surface charge (zeta potential) and electroosmotic mobility associated with a given microchannel substrate material and buffer solution, using a simple current monitoring method to measure the average flow velocity within the microchannel. It is a straightforward experiment designed to help students understand EOF physics while gaining hands-on experience with basic world-to-chip interfacing. It is well suited to a 90-min laboratory session for up to 12 students with minimal infrastructure requirements.
Progress in nanoparticles characterization:Sizing and zeta potential measurement
Institute of Scientific and Technical Information of China (English)
Renliang Xu
2008-01-01
Characterization of various nanoparticles is on the center stage in nanotechnology development. The subjects for nanoparticles characterization are focused on particle size and particle surface charge determinations. This article summarizes the latest development in particle size analysis using dynamic light scattering and surface charge determination using electrophoretic light scattering for nano- or even sub-nanoparticles in concentrated suspensions.
Physical properties of nanofluid suspension of ferromagnetic graphite with high Zeta potential
Energy Technology Data Exchange (ETDEWEB)
Souza, N.S. [Materials and Devices Group, Department of Physics, Universidade Federal de São Carlos, 13565-905 São Carlos, SP (Brazil); Rodrigues, A.D. [Raman Spectroscopy in Nanostructured Materials, Department of Physics, Universidade Federal de São Carlos, 13565-905 São Carlos, SP (Brazil); Cardoso, C.A. [Materials and Devices Group, Department of Physics, Universidade Federal de São Carlos, 13565-905 São Carlos, SP (Brazil); Pardo, H.; Faccio, R.; Mombru, A.W. [Crystallography, Solid State and Materials Laboratory (Cryssmat-Lab), DEQUIFIM, Facultad de Química, Universidad de la República, P.O. Box 1157, CP 11800, Montevideo (Uruguay); Galzerani, J.C. [Raman Spectroscopy in Nanostructured Materials, Department of Physics, Universidade Federal de São Carlos, 13565-905 São Carlos, SP (Brazil); Lima, O.F. de [Instituto de Física “Gleb Wataghin”, UNICAMP, 13083-970 Campinas, SP (Brazil); Sergeenkov, S., E-mail: sergei@df.ufscar [Materials and Devices Group, Department of Physics, Universidade Federal de São Carlos, 13565-905 São Carlos, SP (Brazil); Araujo-Moreira, F.M. [Materials and Devices Group, Department of Physics, Universidade Federal de São Carlos, 13565-905 São Carlos, SP (Brazil)
2012-01-09
We report on the magnetic properties and stability of nanofluid ferromagnetic graphite (NFMG) studied through the measurements of its magnetization hysteresis curves, Raman spectrum and the so-called Zeta potential. The obtained results suggest a robust ferromagnetic behavior of NFMG even at room temperature along with a good stability of the dispersed solution (with Zeta potential around 41.3 mV) and a good reactivity between magnetic graphite and CTAB type cationic surfactant. -- Highlights: ► Magnetic properties and stability of nanofluid ferromagnetic graphite (NFMG) are studied. ► The magnetization hysteresis curves suggest a robust ferromagnetic behavior of NFMG even at room temperature. ► NFMG is found to have Zeta potential around 41.3 mV indicating a good stability of the dispersed solution.
Polysaccharide zeta-potentials and protein-affinity.
Comert, Fatih; Azarikia, Fatemeh; Dubin, Paul L
2017-08-09
The ζ-potential, a parameter typically obtained by model-dependent transformation of the measured electrophoretic mobility, is frequently used to understand polysaccharide-protein complexation. We tested the hypothesis that two anionic polysaccharides with identical ζ-potentials would show equal binding affinity to the protein β-lactoglobulin (BLG). We selected two polysaccharide polyelectrolytes (PE) with very different structures: hyaluronic acid (HA) and tragacanthin (TG). Highly precise (±0.1%) turbidimetric titrations were performed to determine critical pH values of complex formation; and PE ζ-potentials were measured for different ionic strengths I at those critical pH values. While phase boundaries (pHcvs. I) showed that HA binds to BLG more strongly (e.g. at a lower pH, for fixed I), comparisons made at fixed ζ-potential indicated that TG binds more strongly. The source of this contradiction is the effect of the bulky side chains of TG on its friction coefficient which diminishes its mobility and hence the resultant ζ-potential; while having a distinctly separate effect on the interaction between BLG and the carboxylated backbone of TG. Thus, unless the locus of the bound protein coincides with the shear plane, the ζ-potential does not directly contribute to the electrostatic PE-protein interaction.
Voigt, Nadine; Henrich-Noack, Petra; Kockentiedt, Sarah; Hintz, Werner; Tomas, Jürgen; Sabel, Bernhard A
2014-05-01
Nanoparticles (NP) can deliver drugs across the blood-brain barrier (BBB), but little is known which of the factors surfactant, size and zeta-potential are essential for allowing BBB passage. To this end we designed purpose-built fluorescent polybutylcyanoacrylate (PBCA) NP and imaged the NP's passage over the blood-retina barrier - which is a model of the BBB - in live animals. Rats received intravenous injections of fluorescent PBCA-NP fabricated by mini-emulsion polymerisation to obtain various NP's compositions that varied in surfactants (non-ionic, anionic, cationic), size (67-464nm) and zeta-potential. Real-time imaging of retinal blood vessels and retinal tissue was carried out with in vivo confocal neuroimaging (ICON) before, during and after NP's injection. Successful BBB passage with subsequent cellular labelling was achieved if NP were fabricated with non-ionic surfactants or cationic stabilizers but not when anionic compounds were added. NP's size and charge had no influence on BBB passage and cell labelling. This transport was not caused by an unspecific opening of the BBB because control experiments with injections of unlabelled NP and fluorescent dye (to test a "door-opener" effect) did not lead to parenchymal labelling. Thus, neither NP's size nor chemo-electric charge, but particle surface is the key factor determining BBB passage. This result has important implications for NP engineering in medicine: depending on the surfactant, NP can serve one of two opposite functions: while non-ionic tensides enhance brain up-take, addition of anionic tensides prevents it. NP can now be designed to specifically enhance drug delivery to the brain or, alternatively, to prevent brain penetration so to reduce unwanted psychoactive effects of drugs or prevent environmental nanoparticles from entering tissue of the central nervous system.
Adamczyk, Zbigniew; Bratek-Skicki, Anna; Dąbrowska, Paulina; Nattich-Rak, Małgorzata
2012-01-10
The adsorption of fibrinogen on polystyrene latex particles was studied using the concentration depletion method combined with the AFM detection of residual protein after adsorption. Measurements were carried out for a pH range of 3.5-11 and an ionic strength range of 10(-3)-0.15 M NaCl. First, the bulk physicochemical properties of fibrinogen and the latex particle suspension were characterized for this range of pH and ionic strength. The zeta potential and the number of uncompensated (electrokinetic) charges on the protein were determined from microelectrophoretic measurements. It was revealed that fibrinogen molecules exhibited amphoteric characteristics, being on average positively charged for pH adsorption of fibrinogen on latex for pH below 11. It was also proven that fibrinogen adsorption was irreversible, with the maximum surface concentration varying between 2.5 and 5 × 10(3) μm(-2) (weight concentration of a bare molecule was 1.4 to 2.8 mg m(-2)). These measurements revealed two main adsorption mechanisms of fibrinogen: (i) the unoriented (random) mechanism prevailing for lower ionic strength, where adsorbing molecules significantly penetrate the fuzzy polymeric layer on the latex core and (ii) the side-on adsorption mechanism prevailing for pH > 5.8 and a higher ionic strength of 0.15 M. It was also shown that in the latter case, variations in the zeta potential with the protein coverage could be adequately described in terms of the electrokinetic model, previously formulated for planar substrate adsorption. On the basis of these experimental data, an efficient procedure of preparing fibrinogen-covered latex particles of controlled monolayer structure and coverage was envisaged.
Soni, Kamlesh A; Balasubramanian, Ashwin K; Beskok, Ali; Pillai, Suresh D
2008-01-01
The zeta potentials of E. coli, GFP (green fluorescence protein)-labeled E. coli, Salmonella Newport, and Pseudomonas sp. in different states (nutrient-starved and dead) and grown in rich and minimal media were measured. Capillary electrophoresis experiments were conducted to measure the zeta potential of the different cells suspended in a drinking water sample. Salmonella Newport strain showed a lower zeta potential compared to E. coli, GFP-labeled E. coli, and Pseudomonas sp. Starved E. coli cells had a lower zeta potential compared to E. coli cells grown under rich media conditions. Salmonella Newport cells grown in minimal media also had a lower zeta potential compared to rich, starved, and dead cells. The different bacterial cell types exhibited differences in size as well. These results suggest that when bacterial cells are present in drinking water they can exhibit significant heterogeneity in the size and zeta potential, depending on their physiological state.
High-concentration zeta potential measurements using light-scattering techniques.
Kaszuba, Michael; Corbett, Jason; Watson, Fraser Mcneil; Jones, Andrew
2010-09-28
Zeta potential is the key parameter that controls electrostatic interactions in particle dispersions. Laser Doppler electrophoresis is an accepted method for the measurement of particle electrophoretic mobility and hence zeta potential of dispersions of colloidal size materials. Traditionally, samples measured by this technique have to be optically transparent. Therefore, depending upon the size and optical properties of the particles, many samples will be too concentrated and will require dilution. The ability to measure samples at or close to their neat concentration would be desirable as it would minimize any changes in the zeta potential of the sample owing to dilution. However, the ability to measure turbid samples using light-scattering techniques presents a number of challenges. This paper discusses electrophoretic mobility measurements made on turbid samples at high concentration using a novel cell with reduced path length. Results are presented on two different sample types, titanium dioxide and a polyurethane dispersion, as a function of sample concentration. For both of the sample types studied, the electrophoretic mobility results show a gradual decrease as the sample concentration increases and the possible reasons for these observations are discussed. Further, a comparison of the data against theoretical models is presented and discussed. Conclusions and recommendations are made from the zeta potential values obtained at high concentrations.
Phase diagrams of colloidal spheres with a constant zeta-potential
Smallenburg, F.|info:eu-repo/dai/nl/313939039; Boon, N.J.H.|info:eu-repo/dai/nl/313960143; Kater, M.; Dijkstra, M.|info:eu-repo/dai/nl/123538807; van Roij, R.H.H.G.|info:eu-repo/dai/nl/152978984
2011-01-01
We study suspensions of colloidal spheres with a constant zeta-potential within Poisson–Boltzmann theory, quantifying the discharging of the spheres with increasing colloid density and decreasing salt concentration. We use the calculated renormalized charge of the colloids to determine their
Zeta potential of Polish copper-bearing shale in the absence and presence of flotation frothers
Directory of Open Access Journals (Sweden)
Mengsu Peng
2014-09-01
Full Text Available In this paper, zeta potential as a function of pH of copper-bearing shale, which is mined in Poland by KGHM, was investigated. The measurements were conducted in water and aqueous solutions of selected flotation frothers. It was established that for investigated copper-bearing shale, after dispersion in water, the isoelectric point (IEP occurs at pH=3.5. Addition of frothers decreased the IEP on the pH scale and the IEP for butanol was 1.93, for MIBC 2.90 and for eicosaethylene glycol hexadecyl ether (C16E20 2.76. In the case of introducing frothers changed, the zeta potential becomes less negative. An empirical equation, having two adjustable parameters, was used in the paper to approximate the course of the zeta potential-pH curve. The equation showed a very good approximation of the zeta potential of the investigated shale either in water or frother aqueous solutions.
The effect of WWTP effluent zeta-potential on direct nanofiltration performance
Schrader, G.A.; Zwijnenburg, A.; Wessling, Matthias
2005-01-01
Laboratory scale filtration tests utilizing wastewater treatment plants (WWTP) effluent were conducted to investigate fouling and filtration performance of nanofiltration (NF) membranes. The focus of this research is to assess the influence of the zeta-potential of the colloidal fraction in WWTP
Kulsing, Chadin; Yang, Yuanzhong; Matyska, Maria T; Pesek, Joseph J; Boysen, Reinhard I; Hearn, Milton T W
2015-02-15
In this study, the zeta potentials of a silica hydride stationary phase (Diamond Hydride™) in the presence of different water-acetonitrile mixtures (from 0-80% (v/v) acetonitrile) of different ionic strengths (from 0-40mM) and pH values (from pH 3.0-7.0) have been investigated. Debye-Hückel theory was applied to explain the effect of changes in the pH and ionic strength of these aqueous media on the negative zeta potential of this stationary phase. The experimental zeta potentials of the Diamond Hydride™ particles as a function of acetonitrile content up to 50% (v/v) correlated (R(2)=0.998) with the predicted zeta potential values based on this established theory, when the values of the dissociation constant of all related species, as well as viscosity, dielectric constant and refractive index of the aqueous medium were taken into consideration. Further, the retention behavior of basic, acidic and neutral analytes was investigated under mobile phase conditions of higher pH and lower ionic strength. Under these conditions, the Diamond Hydride™ stationary phase surface became more negative, as assessed from the increasingly more negative zeta potentials, resulting in the ion exchange characteristics becoming more dominant and the basic analytes showing increasing retention. Ionic descriptors were derived from these chromatographic experiments based on the assumption that linear solvation energy relationships prevail. The results were compared with predicted ionic descriptors based on the different calculated zeta potential values resulting in an overall correlation of R(2)=0.888. These studies provide fundamental insights into the impact on the separation performance of changes in the zeta potential of the Diamond Hydride™ surface with the results relevant to other silica hydride and, potentially, to other types of stationary phase materials.
Phase diagrams of colloidal spheres with a constant zeta-potential.
Smallenburg, Frank; Boon, Niels; Kater, Maarten; Dijkstra, Marjolein; van Roij, René
2011-02-21
We study suspensions of colloidal spheres with a constant zeta-potential within Poisson-Boltzmann theory, quantifying the discharging of the spheres with increasing colloid density and decreasing salt concentration. We use the calculated renormalized charge of the colloids to determine their pairwise effective screened-Coulomb repulsions. Bulk phase diagrams in the colloid concentration-salt concentration representation follow, for various zeta-potentials, by a mapping onto published fits of phase boundaries of point-Yukawa systems. Although the resulting phase diagrams do feature face-centered cubic and body-centered cubic phases, they are dominated by the (re-entrant) fluid phase due to the colloidal discharging with increasing colloid concentration and decreasing salt concentration.
Electrokinetic mixing at high zeta potentials: ionic size effects on cross stream diffusion.
Ahmadian Yazdi, Alireza; Sadeghi, Arman; Saidi, Mohammad Hassan
2015-03-15
The electrokinetic phenomena at high zeta potentials may show several unique features which are not normally observed. One of these features is the ionic size (steric) effect associated with the solutions of high ionic concentration. In the present work, attention is given to the influences of finite ionic size on the cross stream diffusion process in an electrokinetically actuated Y-shaped micromixer. The method consists of a finite difference based numerical approach for non-uniform grid which is applied to the dimensionless form of the governing equations, including the modified Poisson-Boltzmann equation. The results reveal that, neglecting the ionic size at high zeta potentials gives rise to the overestimation of the mixing length, because the steric effects retard liquid flow, thereby enhancing the mixing efficiency. The importance of steric effects is found to be more intense for channels of smaller width to height ratio. It is also observed that, in sharp contrast to the conditions that the ions are treated as point charges, increasing the zeta potential improves the cross stream diffusion when incorporating the ionic size. Moreover, increasing the EDL thickness decreases the mixing length, whereas the opposite is true for the channel aspect ratio.
Caroni, A L P F; de Lima, C R M; Pereira, M R; Fonseca, J L C
2012-12-01
Adsorption phenomena occurring at the solid/liquid interface of chitosan particles are of extreme importance in the kinetics of drug release/upload as well as in effluent treatment by adsorption. In this work, equilibrium and kinetic aspects of protonated tetracycline adsorption on chitosan are explored using classic solution depletion method and zeta potential measurements. Equilibrium experiments showed that for solutions with tetracycline initial concentration of ca. 1.2 g L(-1), corresponding to a pH around 3, chitosan structure disrupted, as indicated by an increase in magnitude of tetracycline sorption. Adsorption and zeta potential isotherms before disruption suggested that the process of adsorption had a Langmuir character up to a point at which subsurface was exposed to adsorption; at this point, a second mode of sorption began: zeta potential tended to an equilibrium value, following Sips isotherm and tetracycline sorption had a linear dependence on its continuous phase concentration. The kinetics of tetracycline sorption suggested that sorption of tetracycline was divided between the sorption of protonated and non-protonated tetracycline; tetracycline in its non-protonated form seemed to rule the sorption of tetracycline.
Bernsmann, Falk; Frisch, Benoît; Ringwald, Christian; Ball, Vincent
2010-04-01
We recently showed the possibility to build dopamine-melanin films of controlled thickness by successive immersions of a substrate in alkaline solutions of dopamine [F. Bernsmann, A. Ponche, C. Ringwald, J. Hemmerlé, J. Raya, B. Bechinger, J.-C. Voegel, P. Schaaf, V. Ball, J. Phys. Chem. C 113 (2009) 8234-8242]. In this work the structure and properties of such films are further explored. The zeta-potential of dopamine-melanin films is measured as a function of the total immersion time to build the film. It appears that the film bears a constant zeta-potential of (-39+/-3) mV after 12 immersion steps. These data are used to calculate the surface density of charged groups of the dopamine-melanin films at pH 8.5 that are mostly catechol or quinone imine chemical groups. Furthermore the zeta-potential is used to explain the adsorption of three model proteins (lysozyme, myoglobin, alpha-lactalbumin), which is monitored by quartz crystal microbalance. We come to the conclusion that protein adsorption on dopamine-melanin is not only determined by possible covalent binding between amino groups of the proteins and catechol groups of dopamine-melanin but that electrostatic interactions contribute to protein binding. Part of the adsorbed proteins can be desorbed by sodium dodecylsulfate solutions at the critical micellar concentration. The fraction of weakly bound proteins decreases with their isoelectric point. Additionally the number of available sites for covalent binding of amino groups on melanin grains is quantified.
Directory of Open Access Journals (Sweden)
Yazan Haddad
2016-04-01
Full Text Available Magnetic isolation of biological targets is in major demand in the biotechnology industry today. This study considers the interaction of four surface-modified magnetic micro- and nanoparticles with selected DNA fragments. Different surface modifications of nanomaghemite precursors were investigated: MAN37 (silica-coated, MAN127 (polyvinylpyrrolidone-coated, MAN158 (phosphate-coated, and MAN164 (tripolyphosphate-coated. All particles were positive polycharged agglomerated monodispersed systems. Mean particle sizes were 0.48, 2.97, 2.93, and 3.67 μm for MAN37, MAN127, MAN164, and MAN158, respectively. DNA fragments exhibited negative zeta potential of −0.22 mV under binding conditions (high ionic strength, low pH, and dehydration. A decrease in zeta potential of particles upon exposure to DNA was observed with exception of MAN158 particles. The measured particle size of MAN164 particles increased by nearly twofold upon exposure to DNA. Quantitative PCR isolation of DNA with a high retrieval rate was observed by magnetic particles MAN127 and MAN164. Interaction between polycharged magnetic particles and DNA is mediated by various binding mechanisms such as hydrophobic and electrostatic interactions. Future development of DNA isolation technology requires an understanding of the physical and biochemical conditions of this process.
Haddad, Yazan; Xhaxhiu, Kledi; Kopel, Pavel; Hynek, David; Zitka, Ondrej; Adam, Vojtech
2016-04-20
Magnetic isolation of biological targets is in major demand in the biotechnology industry today. This study considers the interaction of four surface-modified magnetic micro- and nanoparticles with selected DNA fragments. Different surface modifications of nanomaghemite precursors were investigated: MAN37 (silica-coated), MAN127 (polyvinylpyrrolidone-coated), MAN158 (phosphate-coated), and MAN164 (tripolyphosphate-coated). All particles were positive polycharged agglomerated monodispersed systems. Mean particle sizes were 0.48, 2.97, 2.93, and 3.67 μm for MAN37, MAN127, MAN164, and MAN158, respectively. DNA fragments exhibited negative zeta potential of -0.22 mV under binding conditions (high ionic strength, low pH, and dehydration). A decrease in zeta potential of particles upon exposure to DNA was observed with exception of MAN158 particles. The measured particle size of MAN164 particles increased by nearly twofold upon exposure to DNA. Quantitative PCR isolation of DNA with a high retrieval rate was observed by magnetic particles MAN127 and MAN164. Interaction between polycharged magnetic particles and DNA is mediated by various binding mechanisms such as hydrophobic and electrostatic interactions. Future development of DNA isolation technology requires an understanding of the physical and biochemical conditions of this process.
Electroosmotic fluid motion and late-time solute transport at non-negligible zeta potentials
Energy Technology Data Exchange (ETDEWEB)
S. K. Griffiths; R. H. Nilson
1999-12-01
Analytical and numerical methods are employed to determine the electric potential, fluid velocity and late-time solute distribution for electroosmotic flow in a tube and channel when the zeta potential is not small. The electric potential and fluid velocity are in general obtained by numerical means. In addition, new analytical solutions are presented for the velocity in a tube and channel in the extremes of large and small Debye layer thickness. The electroosmotic fluid velocity is used to analyze late-time transport of a neutral non-reacting solute. Zeroth and first-order solutions describing axial variation of the solute concentration are determined analytically. The resulting expressions contain eigenvalues representing the dispersion and skewness of the axial concentration profiles. These eigenvalues and the functions describing transverse variation of the concentration field are determined numerically using a shooting technique. Results are presented for both tube and channel geometries over a wide range of the normalized Debye layer thickness and zeta potential. Simple analytical approximations to the eigenvalues are also provided for the limiting cases of large and small values of the Debye layer thickness. The methodology developed here for electroosmotic flow is also applied to the Taylor problem of late-time transport and dispersion in pressure-driven flows.
Effective flocculation of Chlorella vulgaris using chitosan with zeta potential measurement
Low, Y. J.; Lau, S. W.
2017-06-01
Microalgae are considered as one promising source of third-generation biofuels due to their fast growth rates, potentially higher yield rates and wide ranges of growth conditions. However, the extremely low biomass concentration in microalgae cultures presents a great challenge to the harvesting of microalgae because a large volume of water needs to be removed to obtain dry microalgal cells for the subsequent oil extraction process. In this study, the fresh water microalgae Chlorella vulgaris (C. vulgaris) was effectively harvested using both low molecular weight (MW) and high MW chitosan flocculants. The flocculation efficiency was evaluated by physical appearance, supernatant absorbance, zeta potential and solids content after centrifugal dewatering. High flocculation efficiency of 98.0-99.0% was achieved at the optimal dosage of 30-40 mg/g with formation of large microalgae flocs. This study suggests that the polymer bridging mechanism was governing the flocculation behaviour of C. vulgaris using high MW chitosan. Besides, charge patch neutralisation mechanism prevailed at low MW chitosan where lower dosage was sufficient to reach near-zero zeta potential compared with the high MW chitosan. The amount of chitosan polymer present in the culture may also affect the mechanism of flocculation.
Wilson, David R; Green, Jordan J
2017-01-01
Nanoparticle tracking analysis (NTA) is a recently developed nanoparticle characterization technique that offers certain advantages over dynamic light scattering for characterizing polyplex nanoparticles in particular. Dynamic light scattering results in intensity-weighted average measurements of nanoparticle characteristics. In contrast, NTA directly tracks individual particles, enabling concentration measurements as well as the direct determination of number-weighted particle size and zeta-potential. A direct number-weighted assessment of nanoparticle characteristics is particularly useful for polydisperse samples of particles, including many varieties of gene delivery particles that can be prone to aggregation. Here, we describe the synthesis of poly(beta-amino ester)/deoxyribonucleic acid (PBAE/DNA) polyplex nanoparticles and their characterization using NTA to determine hydrodynamic diameter, zeta-potential, and concentration. Additionally, we detail methods of labeling nucleic acids with fluorophores to assess only those polyplex nanoparticles containing plasmids via NTA. Polymeric gene delivery of exogenous plasmid DNA has great potential for treating a wide variety of diseases by inducing cells to express a gene of interest.
Kwaambwa, Habauka M; Rennie, Adrian R
2012-04-01
Protein extracted from Moringa oleifera (MO) seeds has been advocated as a cheap and environmental friendly alternative to ionic flocculants for water purification. However, the nature and mechanism of its interaction with particles in water, as well as with dissolved surface-active molecules, are not well understood. In this article, we report studies of the protein and its interaction with four surfactants using dynamic light scattering (DLS), zeta-potential and turbidity measurements. Zeta-potential measurements identified points of charge reversal and the turbidity and DLS measurements were used to characterize the microstructure and size of protein-surfactant complexes. From the points of charge reversal, it was estimated that 7 anions are required to neutralize the positive charges of each protein molecule at pH 7. For protein mixtures with sodium dodecyl sulfate and dodecyl di-acid sodium salt, the peak in turbidity corresponds to concentrations with a large change in zeta-potential. No turbidity was observed for protein mixtures with either the nonionic surfactant Triton X-100 or the zwitterionic surfactant N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate. Changes of pH in the range 4-10 have little effect on the zeta-potential, turbidity, and the hydrodynamic radius reflecting the high isoelectric point of the protein. Addition of small amounts of salt has little effect on the size of protein in solution. These results are discussed in the context of the use of the MO protein in water treatment.
Influence of zeta potential on the flocculation of cyanobacteria cells using chitosan modified soil.
Li, Liang; Zhang, Honggang; Pan, Gang
2015-02-01
Using chitosan modified soil to flocculate and sediment algal cells has been considered as a promising strategy to combat cyanobacteria blooms in natural waters. However, the flocculation efficiency often varies with algal cells with different zeta potential (ZP) attributed to different growth phases or water conditions. This article investigated the relationship between ZP of Microcystis aeruginosa and its influence to the flocculation efficiency using chitosan modified soil. Results suggested that the optimal removal efficiency was obtained when the ZP was between -20.7 and -6.7 mV with a removal efficiency of more than 80% in 30 min and large floc size of >350 μm. When the algal cells were more negatively charged than -20.7 mV, the effect of chitosan modified soil was depressed (flocculation efficiency of chitosan modified soil and an important guidance for practical engineering of cyanobacteria bloom control.
ZETA POTENTIAL AND COLOR INVESTIGATIONS OF VEGETABLE OIL BASED EMULSIONS AS ECO-FRIENDLY LUBRICANTS
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ROMICĂ CREŢU
2017-06-01
Full Text Available In the past 10 years, the need for biodegradable lubricants has been more and more emphasized. The use of vegetable oils as lubricants offers several advantages. The vegetable oils are biodegradable; thus, the environmental pollution is minimal either during or after their use. The aim of this paper is to presents a preliminary study concerning the influence of some preparation conditions on the stability of vegetable oil-in-water (O/W emulsions as eco-friendly lubricants stabilized by nonionic surfactant. In this context, vegetable oil-in-water emulsions characteristics where assessed using microscopically observation and zeta potential. In addition, the color of these emulsions can be evaluated. It can be observed that the emulsions tend to stabilize in time.
ζ-potential determination using a ZetaMeter-Dynamic Speckle assembly
González-Peña, Rolando J.; Sánchez-Muñoz, Orlando L.; Martínez-Celorio, René A.; Cibrián, Rosa M.; Salvador-Palmer, Rosario; Salgado, Jesús
2012-10-01
Electrophoretic mobility and ζ-potential are important physical parameters for the characterization of micro- and nanosystems. In this communication we describe a new method for determining the ζ-potential through the assembly of two well known techniques: free electrophoresis and Dynamic Speckle. When coherent light passes through a fluid having scattering centres, the far field interference originates a speckled image. If the scattering centres are contained within the cylindrical electrophoresis cell of a ZetaMeter and are forced to move in an orderly way under the action of an external electric field, the time variation of the light intensity in the far field speckle images follows a temporal autocorrelation function g(τ). The corresponding correlation time can then be obtained and related with the velocity, from which the electrophoretic mobility and the ζ-potential of the scattering centres can be determined. We have applied this method to microparticles, like natural air-floated silica and two classes of bioceramics, hydroxyapatite and biphasic calcium phosphate. For comparison, we analysed the same samples in parallel using a commercial Zetasizer Nano from Malvern Instruments. The values of ζ-potential determined using the two techniques were the same within ~3% error. These results validate our new method as a useful and efficient alternative for ζ-potential determination of particles, at least within the micrometer scale.
Energy Technology Data Exchange (ETDEWEB)
Sankhla, Aryan, E-mail: aaryansankhla@gmail.com [Centre for Converging Technologies, University of Rajasthan, Jaipur, 302015 (India); Sharma, Rajeshwar; Yadav, Raghvendra Singh [Centre for Converging Technologies, University of Rajasthan, Jaipur, 302015 (India); Kashyap, Diwakar [Department of Biological Chemistry, Ariel University, Ariel, 40700 (Israel); Kothari, S.L. [Institute of Biotechnology, Amity University, Jaipur, 303002 (India); Kachhwaha, S. [Department of Botany, University of Rajasthan, Jaipur, 302004 (India)
2016-02-15
Biological approaches have been amongst the most promising protocols for synthesis of nanomaterials. In this study, Cadmium sulfide nanoparticles (CdS NPs) were synthesized by incubating their precursor salts with Escherichia coli and zeta potential (ζ-potential) measurement with varying pH was carried out to evaluate stability of the colloidal dispersion. Formation of CdS NPs was studied in synchrony with microbial growth. TEM analysis confirmed the uniform distribution of NPs. Average size (5 ± 0.4 nm) and electron diffraction pattern revealed polycrystalline cubic crystal phase of these nanoparticles. X-ray diffractogram ascertained the formation of CdS nanoparticles with phase formation and particle size distribution in accordance with the particle size obtained from TEM. Absorption edge of biosynthesized CdS NPs showed a blue shift at ∼400 nm in comparison to their bulk counterpart. A hump at 279 nm indicated presence of biomolecules in the solution in addition to the particles. FT-IR spectrum of capped CdS NPs showed peaks of protein. This confirms adsorption of protein molecules on nanoparticle surface. They act as a capping agent hence responsible for the stability of NPs. The enhanced stability of the particles was confirmed by Zeta potential analysis. The presence of charge on the surface of capped CdS NPs gave a detail understanding of dispersion mechanism and colloidal stability at the NP interface. This stability study of biosynthesized semiconductor nanoparticles utilizing microbial cells had not been done in the past by any research group providing an impetus for the same. Surface area of capped CdS NPs and bare CdS NPs were found to be 298 ± 2.65 m{sup 2}/g and 117 ± 2.41 m{sup 2}/g respectively. A possible mechanism is also proposed for the biosynthesis of CdS NPs. - Highlights: • Synthesis of CdS NPs utilizing reproducible molecular machinery viz. Escherichia coli biomass. • Uniform and Polydispersed NPs with high surface area
Nomikos, Michail; Mulgrew-Nesbitt, Anna; Pallavi, Payal; Mihalyne, Gyongyi; Zaitseva, Irina; Swann, Karl; Lai, F Anthony; Murray, Diana; McLaughlin, Stuart
2007-06-01
Phospholipase C-zeta (PLC-zeta) is a sperm-specific enzyme that initiates the Ca2+ oscillations in mammalian eggs that activate embryo development. It shares considerable sequence homology with PLC-delta1, but lacks the PH domain that anchors PLC-delta1 to phosphatidylinositol 4,5-bisphosphate, PIP2. Thus it is unclear how PLC-zeta interacts with membranes. The linker region between the X and Y catalytic domains of PLC-zeta, however, contains a cluster of basic residues not present in PLC-delta1. Application of electrostatic theory to a homology model of PLC-zeta suggests this basic cluster could interact with acidic lipids. We measured the binding of catalytically competent mouse PLC-zeta to phospholipid vesicles: for 2:1 phosphatidylcholine/phosphatidylserine (PC/PS) vesicles, the molar partition coefficient, K, is too weak to be of physiological significance. Incorporating 1% PIP2 into the 2:1 PC/PS vesicles increases K about 10-fold, to 5x10(3) M-1, a biologically relevant value. Expressed fragments corresponding to the PLC-zeta X-Y linker region also bind with higher affinity to polyvalent than monovalent phosphoinositides on nitrocellulose filters. A peptide corresponding to the basic cluster (charge=+7) within the linker region, PLC-zeta-(374-385), binds to PC/PS vesicles with higher affinity than PLC-zeta, but its binding is less sensitive to incorporating PIP2. The acidic residues flanking this basic cluster in PLC-zeta may account for both these phenomena. FRET experiments suggest the basic cluster could not only anchor the protein to the membrane, but also enhance the local concentration of PIP2 adjacent to the catalytic domain.
Interrelationship between the zeta potential and viscoelastic properties in coacervates complexes.
Espinosa-Andrews, Hugo; Enríquez-Ramírez, Karina Esmeralda; García-Márquez, Eristeo; Ramírez-Santiago, Cesar; Lobato-Calleros, Consuelo; Vernon-Carter, Jaime
2013-06-05
The formation of the complex coacervate (CC) phases between gum Arabic (GA) and low molecular weight chitosan (Ch) and the interrelationship between the zeta-potential and viscoelastic properties of the coacervate phase were investigated. The maximum charge difference of biopolymers stock dispersion was displayed in a range of pH between 4.0 and 5.5. Titration experiment between the oppositely charged biopolymers showed that the isoelectric point was found at a biopolymers mass ratio (R[GA:Ch]) of R[5.5:1]. Turbidity, size and ζ-potential of the soluble complexes (SC) showed an interrelation with the complex coacervate yield (CCY). Higher CCY values (82.2-88.1%) were obtained in the range from R[3:1] to R[5.5:1]. Change the R[GA:Ch] in dispersion, make possible to produce CC's phases exhibiting cationic (R[1:1] and R[3:1]), neutral (R[5.5:1]) or anionic (R[9:1] and R[7:1]) charged. All CC's exhibited liquid-viscoelastic behavior at lower frequencies and a crossover between G″ and G' at higher frequencies.
Kaasalainen, Martti; Mäkilä, Ermei; Riikonen, Joakim; Kovalainen, Miia; Järvinen, Kristiina; Herzig, Karl-Heinz; Lehto, Vesa-Pekka; Salonen, Jarno
2012-07-15
Recently, highly promising results considering the use of porous silicon (PSi) nanoparticles as a controlled and targeted drug delivery system have been published. Drugs are typically loaded into PSi nanoparticles by electrostatic interactions, and the drug-loaded nanoparticles are then administered parenterally in isotonic solutions. Zeta potential has an important role in drug adsorption and overall physical stability of nanosuspensions. In the present study, we used zeta potential measurements to study the impact of the formulation components to the nanosuspension stability. The impact of medium was studied by measuring isoelectric points (IEP) and zeta potentials in isotonic media. The role of drug adsorption was demonstrated with gastrointestinal peptides GLP-1(7-37) and PYY (3-36) and the selection of isotonic additive was demonstrated with peptide-loaded PSi nanoparticles. The results show the notable effect of isotonic solutions and peptide adsorption on zeta potential of PSi nanosuspensions. As a rule of thumb, the sugars (sucrose, dextrose and mannitol) seem to be good media for negatively charged peptide-loaded particles and weak acids (citric- and lactic acid) for positively charged particles. Nevertheless, perhaps the most important rule can be given for isotonic salt solutions which all are very poor media when the stability of nanosuspension is considered.
Djerdjev, Alex M; Beattie, James K
2008-08-28
The effects of oil solubility and composition on the zeta potential and drop size of oil-in-water emulsions stabilised by sodium dodecyl sulfate (SDS) were studied by electroacoustics and ultrasonic attenuation. The zeta-potentials of toluene and alkane emulsions were found to decrease (be less negative) as the water solubility of the dispersed oil phase increased. The zeta-potentials also depended on the composition of mixed oils, becoming more negative with increasing mole fraction of an insoluble oil (hexadecane). As the water solubility of the dispersed oil phase increased, the conductance within the Stern layer relative to the diffuse layer (K/K) increased, which is interpreted as due to the displacement of the shear plane further into the diffuse layer. The shear plane was calculated to increase from approximately 0.50 nm at the insoluble oil-water interface (hexadecane) to approximately 2.5 nm at a soluble oil-water interface of toluene. The lowering of the zeta-potentials of the soluble oils is ascribed to the shift of the shear plane into the diffuse layer, resulting in a more diffuse interface. The total surface conductance of the mixed oils was related to the log of the oil solubility and decreased from approximately 7 x 10(-9) Omega(-1) to 3 x 10(-9) Omega(-1) with increasing oil solubility from hexadecane to toluene, respectively. The lower surface conductance at the soluble oil-water interface is attributed to a reduction in the dielectric constant of the water inside of the shear plane, caused by the presence of the soluble oil.
Universal Dielectric Enhancement from Externally Induced Double Layer Without $\\zeta$-Potential
Qian, Jiang
2015-01-01
Motivated by recent experiments showing over $10^4$-fold increase in induced polarization from electrochemically inert, conducting materials in dilute saline solutions, we theoretically demonstrate a new mechanism for dielectric enhancement, in the absence of $\\zeta-$potentials at interfaces between non-insulating particles and an electrolyte solution. We further show that the magnitude of such enhancement obeys universal scaling laws, independent of the particle's electrical properties and valid across particle shapes: for a dilute suspension of identical, but arbitrarily shaped particles of a linear dimension $a$ and volume fraction $f$, as $\\omega\\to0$ the effective real dielectric constant of the mixture is enhanced from that of water by a factor $1+f~(P_r+(a/\\lambda)P_i)$, and the frequency-dependent phase shift of its impedance has a scale-invariant maximum $f\\,\\mathsf{\\Theta}$ if particles are much more conductive than the solution. Here $\\lambda$ is the solution's Debye length and $P_r$, $P_i$, $\\math...
Characterization of PF4-Heparin Complexes by Photon Correlation Spectroscopy and Zeta Potential.
Bertini, Sabrina; Fareed, Jawed; Madaschi, Laura; Risi, Giulia; Torri, Giangiacomo; Naggi, Annamaria
2017-01-01
Heparin-induced thrombocytopenia (HIT) is associated with antibodies to complexes between heparin and platelet factor 4 (PF4), a basic protein usually found in platelet alpha granules. Heparin-induced thrombocytopenia antibodies preferentially recognize macromolecular complexes formed between positively charged PF4 and polyanionic heparins over a narrow range of molar ratios. The aim of this work was to study the complexes that human PF4 forms with heparins from various species, such as porcine, bovine, and ovine; heparins from various organs, such as mucosa and lung; and different low-molecular-weight heparins (LMWHs) at several stoichiometric ratios to evaluate their sizes and charges by photo correlation spectroscopy and zeta potential measurements. The resulting data of the PF4 complexes with unfractionated heparins (UFHs), LMWHs and their fractions, and oligosaccharide components suggest that the size of aggregates is not only a simple function of average molecular weight but also of the molecular weight distribution of the sample. Moreover, it was found that lower concentrations of the tested ovine-derived mucosal heparin are required to form the large PF4/heparin complexes as compared to mucosal porcine and bovine heparin.
Yan, Deguang; Nguyen, Nam-Trung; Yang, Chun; Huang, Xiaoyang
2006-01-14
We have demonstrated a transient micro particle image velocimetry (micro-PIV) technique to measure the temporal development of electroosmotic flow in microchannels. Synchronization of different trigger signals for the laser, the CCD camera, and the high-voltage switch makes this measurement possible with a conventional micro-PIV setup. Using the transient micro-PIV technique, we have further proposed a method on the basis of inertial decoupling between the particle electrophoretic motion and the fluid electroosmotic flow to determine the electrophoretic component in the particle velocity and the zeta potential of the channel wall. It is shown that using the measured zeta potentials, the theoretical predictions agree well with the transient response of the electroosmotic velocities measured in this work.
Kulsing, Chadin; Yang, Yuanzhong; Munera, Caesar; Tse, Colby; Matyska, Maria T; Pesek, Joseph J; Boysen, Reinhard I; Hearn, Milton T W
2014-03-19
In this study, the zeta potentials of type-B silica, bare silica hydride, the so-called Diamond Hydride™ and phenyl substituted silica hydride stationary phases have been measured in aqueous-organic media and correction procedures developed to account for the more negative zeta potential values in media containing different acetonitrile contents. Retention studies of 16 basic, acidic and neutral compounds were also performed with these four stationary phases with mobile phases containing 0.1% (v/v) formic acid and various acetonitrile-water compositions ranging from 0-90% (v/v) acetonitrile. The retention properties of these analytes were correlated to the corrected stationary phase zeta potentials measured under these different mobile phase conditions with R(2) values ranging from 0.01 to 1.00, depending on the stationary phase and analyte type. Using linear solvation energy relationships, stationary phase descriptors for each stationary phase have been developed for the different mobile phase conditions. Very high correlations of the zeta potentials with the ionic interaction descriptors were obtained for the type-B silica and the Diamond Hydride™ phases and good correlation with bare silica hydride material whilst there was no correlation observed for the phenyl substituted silica hydride phase. The nature of the retention mechanisms which gives rise to these different observations is discussed. The described methods represent a useful new approach to characterize and assess the retention properties of silica-hydride based chromatographic stationary phases of varying bonded-phase coverage and chemistries, as would be broadly applicable to other types of stationary phase used in the separation sciences.
Jackson, Matthew D.; Al-Mahrouqi, Dawoud; Vinogradov, Jan
2016-11-01
Laboratory experiments and field trials have shown that oil recovery from carbonate reservoirs can be increased by modifying the brine composition injected during recovery in a process termed controlled salinity water-flooding (CSW). However, CSW remains poorly understood and there is no method to predict the optimum CSW composition. This work demonstrates for the first time that improved oil recovery (IOR) during CSW is strongly correlated to changes in zeta potential at both the mineral-water and oil-water interfaces. We report experiments in which IOR during CSW occurs only when the change in brine composition induces a repulsive electrostatic force between the oil-brine and mineral-brine interfaces. The polarity of the zeta potential at both interfaces must be determined when designing the optimum CSW composition. A new experimental method is presented that allows this. Results also show for the first time that the zeta potential at the oil-water interface may be positive at conditions relevant to carbonate reservoirs. A key challenge for any model of CSW is to explain why IOR is not always observed. Here we suggest that failures using the conventional (dilution) approach to CSW may have been caused by a positively charged oil-water interface that had not been identified.
Quasi-SMILES and nano-QFPR: The predictive model for zeta potentials of metal oxide nanoparticles
Toropov, Andrey A.; Achary, P. Ganga Raju; Toropova, Alla P.
2016-09-01
Building up of the predictive quantitative structure-property/activity relationships (QSPRs/QSARs) for nanomaterials usually are impossible owing to the complexity of the molecular architecture of the nanomaterials. Simplified molecular input-line entry system (SMILES) is a tool to represent the molecular architecture of ;traditional; molecules for "traditional" QSPR/QSAR. The quasi-SMILES is a tool to represent features (conditions and circumstances), which accompany the behavior of nanomaterials. Having, the training set and validation set, so-called quantitative feature-property relationships (QFPRs), based on the quasi-SMILES, one can build up model for zeta potentials of metal oxide nanoparticles for situations characterized by different features.
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Eduardo Alberto López-Maldonado
2014-01-01
Full Text Available Efficiency of coagulation-flocculation process used for semiconductor wastewater treatment was improved by selecting suitable conditions (pH, polyelectrolyte type, and concentration through zeta potential measurements. Under this scenario the zeta potential, ζ, is the right parameter that allows studying and predicting the interactions at the molecular level between the contaminants in the wastewater and polyelectrolytes used for coagulation-flocculation. Additionally, this parameter is a key factor for assessing the efficiency of coagulation-flocculation processes based on the optimum dosages and windows for polyelectrolytes coagulation-flocculation effectiveness. In this paper, strategic pH variations allowed the prediction of the dosage of polyelectrolyte on wastewater from real electroplating baths, including the isoelectric point (IEP of the dispersions of water and commercial polyelectrolytes used in typical semiconductor industries. The results showed that there is a difference between polyelectrolyte demand required for the removal of suspended solids, turbidity, and organic matter from wastewater (23.4 mg/L and 67 mg/L, resp.. It was also concluded that the dose of polyelectrolytes and coagulation-flocculation window to achieve compliance with national and international regulations as EPA in USA and SEMARNAT in Mexico is influenced by the physicochemical characteristics of the dispersions and treatment conditions (pH and polyelectrolyte dosing strategy.
Ranjit, N. K.; Shit, G. C.
2017-09-01
This paper aims to develop a mathematical model for magnetohydrodynamic flow of biofluids through a hydrophobic micro-channel with periodically contracting and expanding walls under the influence of an axially applied electric field. The velocity slip effects have been taken into account at the channel walls by employing different slip lengths due to hydrophobic gating. Different temperature jump factors have also been used to investigate the thermomechanical interactions at the fluid-solid interface. The electromagnetohydrodynamic flow in a microchannel is simplified under the framework of Debye-Hückel linearization approximation. We have derived the closed-form solutions for the linearized dimensionless boundary value problem under the assumptions of long wave length and low Reynolds number. The axial velocity, temperature, pressure distribution, stream function, wall shear stress and the Nusselt number have been appraised for diverse values of the parameters approaching into the problem. Our main focus is to determine the effects of different zeta potential on the axial velocity and temperature distribution under electromagnetic environment. This study puts forward an important observation that the different zeta potential plays an important role in controlling fluid velocity. The study further reveals that the temperature increases significantly with the Joule heating parameter and the Brinkman number (arises due to the dissipation of energy).
Groenink, J; Veerman, ECI; Zandvoort, MS; Van der Mei, HC; Busscher, HJ; Amerongen, AVN
1998-01-01
The adhesion of Actinobacillus actinomycetemcomitans is a virulence factor in the aetiology of periodontitis and is determined by physico-chemical properties, e.g. surface charge and hydrophobicity, of the bacterial cell surface. Although oral surfaces are constantly coated with saliva, few studies
Institute of Scientific and Technical Information of China (English)
GUSEINOV I.Israfil; AKSU Hüseyin
2008-01-01
@@ Using formulae for one-and two-electron integrals of Coulomb interaction potential fk(r)=r-k with non-integer indices k established by one of the authors with the help of complete orthonormal sets of Ψa-exponential-type orbitals(a=1,0,-1,-2,…),we perform the calculations for isoelectronic series of the He atom containing nuclear charges from 2 to 10,where k=1-μ(-1＜μ＜0).For this purpose we have used the dogble-zeta approximation,the configuration interaction and coupled-cluster methods employing the integer-n Slater-type orbitals as basis sets.It is demonstrated that the results of calculations obtained are better than the numerical Hartree-Fock values.
Esteban, Patricia Perez; Jenkins, A Toby A; Arnot, Tom C
2016-03-01
In earlier work we have demonstrated the effect that nano-emulsions have on bacterial growth, and most importantly the enhanced bacteriophage infectivity against Staphylococcus aureus in planktonic culture when phage are carried in nano-emulsions. However, the mechanisms of enhancement of the bacteriophage killing effect are not specifically understood. This work focuses on the investigation of the possible interactions between emulsion droplets and bacterial cells, between emulsion droplets and bacteriophages, and finally interactions between all three components: nano-emulsion droplets, bacteria, and bacteriophages. The first approach consists of simple calculations to determine the spatial distribution of the components, based on measurements of particle size. It was found that nano-emulsion droplets are much more numerous than bacteria or bacteriophage, and due to their size and surface area they must be covering the surface of both cells and bacteriophage particles. Stabilisation of bacteriophages due to electrostatic forces and interaction with nano-emulsion droplets is suspected, since bacteriophages may be protected against inactivation due to 'charge shielding'. Zeta potential was measured for the individual components in the system, and for all of them combined. It was concluded that the presence of nano-emulsions could be reducing electrostatic repulsion between bacterial cells and bacteriophage, both of which are very negatively 'charged'. Moreover, nano-emulsions lead to more favourable interaction between bacteriophages and bacteria, enhancing the anti-microbial or killing effect. These findings are relevant since the physicochemical properties of nano-emulsions (i.e. particle size distribution and zeta potential) are key in determining the efficacy of the formulation against infection in the context of responsive burn wound dressings-which is the main target for this work.
Deleurence, Rémi; Parneix, Caroline; Monteux, Cécile
2014-09-28
We investigate the stabilization of air-water interfaces by mixtures of negatively charged latex particles (sulfate polystyrene) and cationic surfactants (alkyl trimethylammonium bromides). First we report results concerning the binding of surfactant molecules to the latex particles. As the surfactant concentration increases, the charge of the particles reverses, from negative to positive, because CnTAB first binds electrostatically to the latex particles and then through hydrophobic interaction with the monolayer already adsorbed on the particles as well as directly with the hydrophobic surface of the latex. Over a large range of surfactant concentrations around the charge inversion, a strong flocculation is observed and 100 μm large aggregates form in the suspension. Unlike previous studies published on mixtures of inorganic particles with oppositely charged surfactants, we show that we can vary the sign of the zeta potential of the particles without changing the contact angle of the particles over a large range of surfactant concentrations. Indeed, the latex particles that we study are more hydrophobic than inorganic particles, hence adding moderate concentrations of the surfactant results in a weak variation of the contact angle while the charge of the particles can be reversed. This enables decoupling of the effect of zeta potential and contact angle on the interfacial properties of the mixtures. Our study shows that the contact angle and the charge of the particles are not sufficient parameters to control the foam properties, and the key-parameters are the flocculation state and the shear energy applied to produce the foam. Indeed, flocculated samples, whatever the sign of the zeta potential, enable production of a stable armour at the interface. The large aggregates do not adsorb spontaneously at the interface because of their large size, however when a large shear energy is used to produce the foam very stable foam is obtained, where particles are trapped
Ferraz, M P; Monteiro, F J; Serro, A P; Saramago, B; Gibson, I R; Santos, J D
2001-12-01
Multilayered plasma sprayed coatings on the surface of Ti-6Al-4V alloys have been prepared, which were composed of an underlayer of HA and a surface layer of a CaO-P2O5 glass-HA composite, with 2 or 4wt% of glass. Contact angle and surface tension variation with time, for both water and a protein solution, were determined by the sessile and pendent drop methods respectively using the ADSA-P software. Wettability studies showed that hydrophobicity of the coatings increase with the glass addition. The work of adhesion of albumin was also altered in a controlled manner by the addition of the CaO-P2O5 glass, being lower on the composite coatings than on HA. Zeta potential (ZP) results showed that composite coatings presented a higher net negative charge than HA coatings and that ZP values were also influenced by the content of the glass. This study demonstrated that the surface properties of those coatings may be modified by the addition of CaO-P2O5 glass.
DEFF Research Database (Denmark)
Geisler, C; Kuhlmann, J; Rubin, B
1989-01-01
The TCR/CD3 complex is a multimeric protein complex composed of a minimum of seven transmembrane chains (TCR alpha beta-CD3 gamma delta epsilon zeta 2). Whereas earlier studies have demonstrated that both the TCR-alpha and -beta chains are required for the cell surface expression of the TCR/CD3 c...... to form the heptameric complex (TCR alpha beta-CD3 gamma delta epsilon----TCR alpha beta-CD3 gamma delta epsilon 2); and 5) CD3-zeta is required for the export of the TCR/CD3 complex from the endoplasmic reticulum to the Golgi apparatus for subsequent processing....
Directory of Open Access Journals (Sweden)
Safi, B.
2011-09-01
Full Text Available This study aimed to analyse the re-use of dam silt as a supplementary binder for self-compacting concrete (SCC. When burnt, silt becomes more reactive because the kaolin it contains is converted into metakaolin. Portland cement, calcined or burnt silt and ground granulated blast furnace slag were used in this research. Cement pastes were prepared with blends containing two or three of these materials. The replacement ratio for burnt silt in both cases was 10 % and 20 % by cement weight and the ratio for the slag was a constant 30 % by weight of the blend. Rheological and zeta potential tests were conducted to evaluate paste electrokinetics and rheological behaviour. The findings showed that burnt silt is apt for use as an addition to cement for SCC manufacture.
En el presente trabajo se ha analizado la posibilidad de utilizar los lodos procedentes de embalses como adición en la fabricación del hormigón autocompactante (HAC. Con la calcinación, estos materiales se vuelven más reactivos debido a la transformación en metacaolín, del caolín que forma parte de su composición. Las materias primas empleadas en esta investigación son: cemento Pórtland, lodos de embalse calcinados y escorias granuladas de horno alto. Se prepararon pastas de cemento con mezclas que contenían dos o tres de estos materiales. El porcentaje de reemplazo de los lodos calcinados osciló entre el 10 y el 20 % en peso del cemento, mientras que el de la escoria fue del 30 % en peso de la mezcla. Se llevaron a cabo ensayos reológicos y de potencial zeta para evaluar el comportamiento electrocinético y reológico de las distintas pastas. De acuerdo con los resultados obtenidos, una vez calcinados, los lodos de embalse son aprovechables como adición al cemento con destino a la preparación de HAC.
Qian, Jiang
2016-01-01
We solve exactly the dielectric response of a non-insulating sphere of radius $a$ suspended in symmetric, univalent electrolyte solution, with ideally-polarizable interface but without significant $\\zeta$-potential. We then use this solution to derive the dielectric response of a dilute random suspension of such spheres, with volume fraction $f\\ll1$, within the Maxwell-Garnett Effective Medium Approximation. Surprisingly, we discover a huge dielectric enhancement in this bare essential model of dielectric responses of solids in electrolyte solution: at low frequency $\\omega\\tau_D \\ll (\\lambda/a) / (\\sigma_w / \\sigma_s+1/2)$, the real part of the effective dielectric constant of the mixture is $1-(3f/2)+(9f/4)(a/\\lambda)$. Here $\\sigma_{w/s}$ is the conductivity of the electrolyte solution/solids, $\\lambda$ is the Debye screening length in the solution, $\\tau_D=\\lambda^2/D$ is the standard time scale of diffusion and $D$ is the ion diffusion coefficient. As $\\lambda$ is of the order nm even for dilute electrol...
Zeta Potential Study on the Bio-oxidation of Copper Sulfide Minerals%硫化铜矿细菌氧化的Zeta电位研究
Institute of Scientific and Technical Information of China (English)
傅开彬; 林海
2012-01-01
为了研究矿物与细菌相互作用后矿物的Zeta电位与细菌对矿物的氧化能力之间的关系，利用Zeta电位仪检测与细菌作用前后硫化矿的Zeta电位，根据Zeta电位和IEP（Iso Electric Point）的变化，判断细菌对硫化矿的氧化作用及其程度。结果表明，硫化铜矿与细菌作用后，矿物的Zeta电位降低，辉铜矿、斑铜矿和铜蓝的IEP向铜的氢氧化物方向移动，而黄铜矿向细菌的IEP方向靠近，分析原因主要是由于各矿物被细菌氧化的程度不同。对与细菌相互作用后的铜蓝进行XPS测试结果证实其表面被氧化。研究证实了细菌对硫化矿的直接氧化作用，同时也得出不同硫化铜的细菌氧化顺序：辉铜矿〉斑铜矿〉铜蓝〉黄铜矿。%The direct bacterial oxidation of sulphide minerals was evaluated by Zeta potential and the iso- electric point (IEP). The results show that copper sulphide minerals have been directly oxidized by the bacteria, after conditioning with Acidithiobacillus ferrooxidans, the Zeta potential of copper sulphide de- creased and became negative, the IEP of chalcoeite, bornite and covellite moved towards the IEP of cop- per hydroxide, however, the IEP of chalcopyrite was very close to that of bacteria. The XPS of covellite after conditioning with bacteria indicates the surface was oxidized. The results support the direct mecha- nism of sulphide minerals bio-oxidation from a new viewpoint. The following order for the bio-oxidation of these minerals is obtained ~ chalcocite 〉 bornite 〉 covellite 〉 chalcoovrite.
Mela, Petra; Berg, van den Albert; Fintschenko, Yolanda; Cummings, Eric B.; Simmons, Blake A.; Kirby, Brian J.
2005-01-01
While cyclo-olefin polymer microchannels have the potential to improve both the optical detection sensitivity and the chemical resistance of polymer microanalytical systems, their surface properties are to date not thoroughly characterized. These surface properties dictate, among other things, elect
Directory of Open Access Journals (Sweden)
Ngoc Thuy Vo
2016-01-01
Full Text Available Quantum dots have been considered to be promising candidates for bioapplications because of their high sensitivity, rapid response, and reliability. The synthesis of high-quality quantum dots that can be dissolved in water and other biological media is a crucial step toward their further application in biology. Starting with a one-pot reaction and the successive ionic layer adsorption and reaction (SILAR method, we produced the CdSe/ZnS core/shell structure. Through a ligand-exchange mechanism, we coated the as-made CdSe/ZnS structure with 3-mercaptopropionic acid (MPA or mercaptosuccinic acid (MSA. Various techniques, including photoluminescence (PL, ultraviolet-visible (UV-Vis spectroscopy, transmission electron microscopy (TEM, X-ray diffraction (XRD, and Fourier transform infrared (FTIR spectroscopy, were utilized to characterize the ligand-coated CdSe/ZnS structure. The results show enhanced luminescence intensity, CdSe surface passivation by ZnS, and successful coating with MPA and MSA. The stability of quantum dots in solutions with different pH values was investigated by performing zeta potential measurements. The results revealed that the quantum dots shifted from displaying hydrophobic to hydrophilic behavior and could be connected with bioagents.
Energy Technology Data Exchange (ETDEWEB)
Mahaki, Hanie, E-mail: hanieh.mahaki@gmail.com [Department of Biology, Faculty of Sciences, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of); Memarpoor-Yazdi, Mina; Chamani, Jamshidkhan [Department of Biology, Faculty of Sciences, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of); Reza Saberi, Mohammad [Medical Chemistry Department, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad (Iran, Islamic Republic of)
2013-02-15
The aim of the present study was to describe the competition of ropinirole hydrochloride (RP) and aspirin (ASA) in binding to human serum albumin (HSA) in physiological buffer (pH=7.4) using multi-spectroscopic, molecular modeling and zeta-potential measurements. Fluorescence analysis was used to define the binding and quenching properties of drug-HSA complexes in binary and ternary systems. Fluorescence spectroscopy showed that in the presence of RP, the binding constant of HSA-ASA was increased. Static quenching was confirmed to result in the fluorescence quenching and FRET. The effect of drugs on the conformation of HSA was analyzed using synchronous fluorescence spectroscopy, three-dimensional fluorescence spectra and circular dichroism (CD). The RLS method determined the critical aggregation concentration of drugs on HSA in binary and ternary systems that confirmed the zeta potential results. Structural modeling showed that the affinity of each of the drugs to HSA in binary and ternary systems confirms the spectroscopic results. - Highlights: Black-Right-Pointing-Pointer We studied the interaction of ropinirole hydrochloride and aspirin with HSA. Black-Right-Pointing-Pointer Molecular modeling and zeta-potential used to describe competitive interaction. Black-Right-Pointing-Pointer We determined the critical induced aggregation concentration of both drugs on HSA. Black-Right-Pointing-Pointer The binding mechanism of drugs as separate and simultaneous to HSA has been compared. Black-Right-Pointing-Pointer The binding site of both drugs as simultaneous effects on HSA has been determined.
Institute of Scientific and Technical Information of China (English)
于养信; 吴建中; 高光华
2004-01-01
Density functional theory is applied to predicting the structures and electrostatic potentials of planar electrochemical surfaces within the framework of the restricted primitive model where small ions are represented by charged hard spheres of equal diameter and the solvent is assumed to be a continuous dielectric medium. The hard-sphere contribution to the excess Helmholtz energy functional is evaluated using the modified fundamentalmeasure theory and the electrostatic contribution is obtained from the quadratic functional Taylor expansion using the second-order direct correlation function from the mean-spherical approximation. Numerical results for the ionic density profiles and the mean electrostatic potentials near a planar surface of various charge densities are in excellent agreement with molecular simulations. In contrast to the modified Gouy-Chapman theory, the present density functional theory correctly predicts the second layer formation and charge inversion of charged surfaces as observed in simulations and in experiments. The theory has also been tested with the zeta potentials of positively charged polystyrene particles in aqueous solutions of KBr. Good agreement is achieved between the calculated and experimental results.
Degenerate Euler zeta function
Kim, Taekyun
2015-01-01
Recently, T. Kim considered Euler zeta function which interpolates Euler polynomials at negative integer (see [3]). In this paper, we study degenerate Euler zeta function which is holomorphic function on complex s-plane associated with degenerate Euler polynomials at negative integers.
Kargın, Levent; Kurt, Veli
2015-01-01
In this study, obtaining the matrix analog of the Euler's reflection formula for the classical gamma function we expand the domain of the gamma matrix function and give a infinite product expansion of sinπxP. Furthermore we define Riemann zeta matrix function and evaluate some other matrix integrals. We prove a functional equation for Riemann zeta matrix function.
Soema, Peter C; Willems, Geert-Jan; Jiskoot, Wim; Amorij, Jean-Pierre; Kersten, Gideon F
2015-08-01
In this study, the effect of liposomal lipid composition on the physicochemical characteristics and adjuvanticity of liposomes was investigated. Using a design of experiments (DoE) approach, peptide-containing liposomes containing various lipids (EPC, DOPE, DOTAP and DC-Chol) and peptide concentrations were formulated. Liposome size and zeta potential were determined for each formulation. Moreover, the adjuvanticity of the liposomes was assessed in an in vitro dendritic cell (DC) model, by quantifying the expression of DC maturation markers CD40, CD80, CD83 and CD86. The acquired data of these liposome characteristics were successfully fitted with regression models, and response contour plots were generated for each response factor. These models were applied to predict a lipid composition that resulted in a liposome with a target zeta potential. Subsequently, the expression of the DC maturation factors for this lipid composition was predicted and tested in vitro; the acquired maturation responses corresponded well with the predicted ones. These results show that a DoE approach can be used to screen various lipids and lipid compositions, and to predict their impact on liposome size, charge and adjuvanticity. Using such an approach may accelerate the formulation development of liposomal vaccine adjuvants.
Tavakol, Shima; Hoveizi, Elham; Kharrazi, Sharmin; Tavakol, Behnaz; Karimi, Shabnam; Rezayat Sorkhabadi, Seyed Mahdi
2017-06-01
Recently, it has been disclosed that silver nanoparticles (AgNPs) have the potential to inhibit infection and cancerous cells and eventually penetrate through injected site into the capillary due to their small size. This study focuses on the effect of size and zeta potential of bare and citrate-coated AgNPs on human umbilical vein endothelial cells (HUVECs) as main capillary cells. AgNPs with high and low concentrations and no citrate coating were synthesized by using simple wet chemical method and named as AgNP/HC, AgNP/LC, and AgNP, respectively. Citrate coated particles showed larger zeta potential of -22 mV and AgNp/HC showed the smallest size of 13.2 nm. UV-Visible spectroscopy and dynamic light scattering (DLS) were performed to evaluate particle size and hydrodynamic diameter of NPs in water and cell culture media. Results indicated that higher concentrations of citrate decreased hydrodynamic diameter and NP agglomeration. reactive oxygen species (ROS) production of all AgNPs was similar at 28 ppm although it was significantly higher than control group. Their effects on cell membrane and chromosomal structure were studied using LDH measurement and 4',6-diamidino-2-phenylindole (DAPI) staining, as well. Results demonstrated that AgNP/LC was less toxic to cells owing to higher value of IC50, minimum inhibitory concentration (MIC), and less release of LDH. Cancerous (Human Caucasian neuroblastoma) and immortal cells (Mouse embryonic fibroblast cell line) were about twice more sensitive than HUVECs to toxic effects of AgNPs. DAPI staining results showed that AgNP and AgNP/HC induced highest and lowest breaking of chromosome. Overall results suggest that viability of HUVECs will be higher than 90% when viability of cancerous cells is 50% in AgNPs chemotherapy.
Directory of Open Access Journals (Sweden)
Mohammad Reza Saberi
2012-03-01
Full Text Available For the first time, the binding of ropinirole hydrochloride (ROP and aspirin (ASA to human holo-transferrin (hTf has been investigated by spectroscopic approaches (fluorescence quenching, synchronous fluorescence, time-resolved fluorescence, three-dimensional fluorescence, UV-vis absorption, circular dichroism, resonance light scattering, as well as zeta potential and molecular modeling techniques, under simulated physiological conditions. Fluorescence analysis was used to estimate the effect of the ROP and ASA drugs on the fluorescence of hTf as well as to define the binding and quenching properties of binary and ternary complexes. The synchronized fluorescence and three-dimensional fluorescence spectra demonstrated some micro-environmental and conformational changes around the Trp and Tyr residues with a faint red shift. Thermodynamic analysis displayed the van der Waals forces and hydrogen bonds interactions are the major acting forces in stabilizing the complexes. Steady-state and time-resolved fluorescence data revealed that the fluorescence quenching of complexes are static mechanism. The effect of the drugs aggregating on the hTf resulted in an enhancement of the resonance light scattering (RLS intensity. The average binding distance between were computed according to the forster non-radiation energy transfer theory. The circular dichroism (CD spectral examinations indicated that the binding of the drugs induced a conformational change of hTf. Measurements of the zeta potential indicated that the combination of electrostatic and hydrophobic interactions between ROP, ASA and hTf formed micelle-like clusters. The molecular modeling confirmed the experimental results. This study is expected to provide important insight into the interaction of hTf with ROP and ASA to use in various toxicological and therapeutic processes.
Lint, de W.B. Samuel; Benes, Nieck E.; Lyklema, Johannes; Bouwmeester, Henny J.M.; Linde, van der Ab J.; Wessling, Matthias
2003-01-01
Theoretical models for the prediction of nanofiltration separation performance as a function of, e.g., pH and electrolyte composition require knowledge on the ion-surface adsorption chemistry. Adsorption parameters have been extracted from electrophoretic mobility measurements on a ceramic y-alumina
Remarks on Shintani's zeta function
Wakayama, Masato
2005-01-01
We introduce a zeta function attached to a representation of a group. We show that the multi-dimensional zeta function due to Shintani [Sh 1], which is a generalization of the multiple Hurwitz zeta function, can be obtained in this framework. We also construct a gamma function from the zeta function attached to a representation via zeta regularization. We study then a $q$-analogue of the Shintani zeta function and the corresponding gamma function. A sine function defined via the reflection fo...
Flajolet, Philippe; Vepstas, Linas
2008-10-01
Finite differences of values of the Riemann zeta function at the integers are explored. Such quantities, which occur as coefficients in Newton series representations, have surfaced in works of Bombieri-Lagarias, Maslanka, Coffey, Báez-Duarte, Voros and others. We apply the theory of Nörlund-Rice integrals in conjunction with the saddle-point method and derive precise asymptotic estimates. The method extends to Dirichlet L-functions and our estimates appear to be partly related to earlier investigations surrounding Li's criterion for the Riemann hypothesis.
Streaming potential revisited: the influence of convection on the surface conductivity.
Saini, Rakesh; Garg, Abhinandan; Barz, Dominik P J
2014-09-16
Electrokinetic phenomena play an important role in the electrical characterization of surfaces. In terms of planar or porous substrates, streaming potential and/or streaming current measurements can be used to determine the zeta potential of the substrates in contact with aqueous electrolytes. In this work, we perform electrical impedance spectroscopy measurements to infer the electrical resistance in a microchannel with the same conditions as for a streaming potential experiment. Novel correlations are derived to relate the streaming current and streaming potential to the Reynolds number of the channel flow. Our results not only quantify the influence of surface conductivity, and here especially the contribution of the stagnant layer, but also reveal that channel resistance and therefore zeta potential are influenced by the flow in the case of low ionic strengths. We conclude that convection can have a significant impact on the electrical double layer configuration which is reflected by changes in the surfaces conductivity.
Bilateral zeta functions and their applications
Shibukawa, Genki
2011-01-01
We introduce a new type of multiple zeta functions, which we call bilateral zeta functions, analogous to the Barnes zeta functions. The bilateral zeta function is a periodic function and shares certain basic properties of Barnes zeta function. Especially, we prove that the bilateral zeta function has a nice Fourier series expansion and the Barnes zeta function can be expressed as a finite sum of bilateral zeta functions. By these properties of the bilateral zeta functions, We obtain simple pr...
Shao, Qing-Chun; Zhang, Cui-Juan; Li, Jie
2014-10-14
The protein kinase C (PKC) is a family of serine/threonine kinases with a broad range of cellular targets. Members of the PKC family participate at the diverse biological events involved in cellular proliferation, differentiation and survival. The PKC isoform zeta (PKCζ) is an atypical member that has recently been found to play an essential role in promoting human uterine contractility and thus been raised as a new target for treating preterm labour and other tocolytic diseases. In this study, an integrative protocol was described to graft hundreds of inhibitor ligands from their complex crystal structures with cognate kinases into the active pocket of PKCζ and, based on the modeled structures, to evaluate the binding strength of these inhibitors to the non-cognate PKCζ receptor by using a consensus scoring strategy. A total of 32 inhibitors with top score were compiled, and eight out of them were tested for inhibitory potency against PKCζ. Consequently, five compounds, i.e. CDK6 inhibitor fisetin, PIM1 inhibitor myricetin, CDK9 inhibitor flavopiridol and PknB inhibitor mitoxantrone as well as the promiscuous kinase inhibitor staurosporine showed high or moderate inhibitory activity on PKCζ, with IC50 values of 58 ± 9, 1.7 ± 0.4, 108 ± 17, 280 ± 47 and 0.019 ± 0.004 μM, respectively, while other three compounds, including two marketed drugs dasatinib and sunitinib as well as the Rho inhibitor fasudil, have not been detected to possess observable activity. Next, based on the modeled structure data we modified three flavonoid kinase inhibitors, i.e. fisetin, myricetin and flavopiridol, to generate a number of more potential molecular entities, two of which were found to have a moderately improved activity as compared to their parent compounds.
Zeta-spectroscopy beyond 40 GeV
Energy Technology Data Exchange (ETDEWEB)
Buchmueller, W.
1981-01-01
The zeta-family of bound states, formed by the anticipated t-quark and its antiquark, is discussed. The quantitative connection between the zeta-spectroscopy and the short distance behavior of the quark-antiquark potential is examined. It is pointed out that the next quarkonium system will lead to an accurate determination of the QCD scale parameter ..lambda... Weak zeta-decays are briefly considered.
Deryabin, Dmitry G.; Ludmila V. Efremova; Vasilchenko, Alexey S.; Saidakova, Evgeniya V; Sizova, Elena A.; Pavel A. Troshin; Zhilenkov, Alexander V; Khakina, Ekaterina E
2015-01-01
Background The cause–effect relationships between physicochemical properties of amphiphilic [60]fullerene derivatives and their toxicity against bacterial cells have not yet been clarified. In this study, we report how the differences in the chemical structure of organic addends in 10 originally synthesized penta-substituted [60]fullerene derivatives modulate their zeta potential and aggregate’s size in salt-free and salt-added aqueous suspensions as well as how these physicochemical characte...
Interpolation of multiple zeta and zeta-star values
Yamamoto, Shuji
2012-01-01
We define polynomials of one variable t whose values at t=0 and 1 are the multiple zeta values and the multiple zeta-star values, respectively. We give an application to the two-one conjecture of Ohno-Zudilin, and also prove the cyclic sum formula for these polynomials.
Energy Technology Data Exchange (ETDEWEB)
Memarpoor-Yazdi, Mina [Department of Biology, Faculty of Sciences, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of); Mahaki, Hanie, E-mail: hanieh.mahaki@gmail.com [Department of Biology, Faculty of Sciences, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of)
2013-04-15
This study was designed to examine the interaction of Riboflavin (RB) and L-Arginine (L-Arg) with human serum albumin (HSA) using different spectroscopic, zeta potential and molecular modeling techniques under imitated physiological conditions. The resonance light scattering (RLS) method determined the critical aggregation concentration of RB on HSA in the presence and absence of L-Arg which confirmed the zeta potential results. The binding constants (K{sub a}) of HSA–RB were 2.5×10{sup 4} and 9.7×10{sup 3} M{sup −1}, respectively in binary and ternary system at the excitation wavelength of 280 nm, also were 7.5×10{sup 3} and 7.3×10{sup 3}, respectively in binary and ternary system at the excitation wavelength of 295 nm. Fluorescence spectroscopy demonstrated that in the presence of L-Arg, the binding constant of HSA–RB was increased. Static quenching was confirmed to results in the fluorescence quenching and FRET. The binding distances between HSA and RB in two- and three-component systems were estimated by the Forster theory which revealed that nonradiative energy transfer from HSA to RB occurred with a high probability. The effect of RB on the conformation of HSA was analyzed using synchronous fluorescence spectroscopy and circular dichroism (CD) in both systems. Docking studies demonstrated a reduction in the binding affinity between RB and HSA in the presence of L-Arg. -- Highlights: ► We studied the interaction of riboflavin with HSA in presence and absence of L-Arg. ► Molecular modeling and zeta-potential used to describe competitive interaction. ► We compared the binding mechanism of riboflavin (RB) to HSA in both systems. ► We determined critical aggregation concentration of RB on HSA in both systems. ► The binding site of RB on HSA in both systems has been determined.
Ab initio adiabatic and quasidiabatic potential energy surfaces of H++ CN system
Indian Academy of Sciences (India)
Bhargava Anusuri; Sanjay Kumar
2016-02-01
We present restricted geometry (collinear and perpendicular approaches of proton) ab initio three dimensional potential energy surfaces for H++ CN system. The calculations were performed at the internally contracted multi-reference configuration interaction level of theory using Dunning’s correlation consistent polarized valence triple zeta basis set. Adiabatic and quasidiabatic surfaces have been computed for the ground and the first excited electronic states. Nonadiabatic effects arising from radial coupling have been analyzed in terms of nonadiabatic coupling matrix elements and coupling potentials.
Sun, Zhi-Wei
2012-01-01
Let m be a positive integer. We introduce a new zeta function zeta_m(s) defined by zeta_m(s) = sum_{n>0(-e^{2*pi*i/m})^{Omega(n)}/n^s for Re(s)>1, where Omega(n) denotes the total number of prime factors of n (counted with multiplicity). We show that sum_{n\\le x}(-e^{2*pi*i/3})^{Omega(n)}/n is asymptotically equivalent to c(log x)^{(1-sqrt{-3})/2} with c a nonzero complex number, and that sum_{n\\le x}(-e^{2*pi*i/m})^{Omega(n)}/n=O(1) for all m=4,5,6,... We note that zeta_m(s)*sum_{n>0}mu_m(n)/n^s=1 for Re(s)>1, where mu_m(n)=e^{2*pi*i*Omega(n)/m} if n is squarefree, and mu_m(n)=0 otherwise. We also prove that sum_{n>0}mu_3(n)/n=0, which is similar to the known identity sum_{n>0}mu(n)/n=0 equivalent to the Prime Number Theorem. In contrast with the Riemann Hypothesis, we raise the following new hypothesis: zeta_m(1):=sum_{n>0}(-e^{2*pi*i/m})^{Omega(n)}/n=0 for all m=5,6,....
Bilateral zeta functions and their applications
Shibukawa, Genki
2011-01-01
We introduce a new type of multiple zeta functions, which we call bilateral zeta functions, analogous to the Barnes zeta functions. The bilateral zeta function is a periodic function and shares certain basic properties of Barnes zeta function. Especially, we prove that the bilateral zeta function has a nice Fourier series expansion and the Barnes zeta function can be expressed as a finite sum of bilateral zeta functions. By these properties of the bilateral zeta functions, We obtain simple proofs of some formulas, for example the reflection formula for the multiple gamma function, the inversion formula of the Dedekind eta function, Ramanujan's formula, Fourier expansion of the Barnes zeta function and multiple Iseki's formula.
Hosainzadeh, Akram; Gharanfoli, Mohsen; Saberi, Mohammad; Chamani, JamshidKhan
2012-01-01
Here, we report on the effect of aspirin (ASA), on the binding parameters with regard to bilirubin (BR) to human serum albumin (HSA). Two different classes of binding sites were detected. Binding to the first and second classes of the binding sites was dominated by hydrophobic forces in the case of HSA-BR, whereas in the case of the ternary system, binding to the first and second classes of the binding sites was achieved by electrostatic interaction. The binding constant (K(a)) and number of binding site (n) obtained were 1.6 × 10(6)M(-1) and 0.98, respectively, for the primary binding site in the case of HSA-BR, and 3.7 × 10(6)M(-1) and 0.84, respectively, in the presence of ASA (ternary complex) at λ(ex)= 280 nm. The progressive quenching of the protein fluorescence as the BR concentration increased indicated an arrangement of the domain IIA in HSA. Changes in the environment of the aromatic residues were also observed by synchronous fluorescence spectroscopy (SFS). Changes of the secondary structure of HSA involving a decrease of α-helical and β-sheet contents and increased amounts of turns and unordered conformations were mainly found at high concentrations of BR. For the first time, the relationship between the structural parameters of HSA-BR by RLS for determining the critical induced aggregation concentration (C(CIAC)) of BR in the absence and presence of ASA was investigated, and there was a more significant enhancement in the case of the ternary mixture as opposed to the binary one. Changes in the zeta potential of HSA and the HSA-ASA complex in the presence of BR demonstrated a hydrophobic adsorption of this anionic ligand onto the surface of HSA in the binary system as well as both electrostatic and hydrophobic adsorption in the case of the ternary complex. By performing docking experiments, it was found that the acting forces between BR and HSA were mainly hydrophobic > hydrogen bonding > electrostatic interactions, and consequently BR had a long
Proof of Riemann's zeta-hypothesis
Bergstrom, Arne
2008-01-01
Make an exponential transformation in the integral formulation of Riemann's zeta-function zeta(s) for Re(s) > 0. Separately, in addition make the substitution s -> 1 - s and then transform back to s again using the functional equation. Using residue calculus, we can in this way get two alternative, equivalent series expansions for zeta(s) of order N, both valid inside the "critical strip", i e for 0 < Re(s) < 1. Together, these two expansions embody important characteristics of the zeta-funct...
An integral involving the generalized zeta function
Directory of Open Access Journals (Sweden)
E. Elizalde
1990-01-01
Full Text Available A general value for ∫abdtlogΓ(t, for a, b positive reals, is derived in terms of the Hurwitz ζ function. That expression is checked for a previously known special integral, and the case where a is a positive integer and b is half an odd integer is considered. The result finds application in calculating the numerical value of the derivative of the Riemann zeta function at the point −1, a quantity that arises in the evaluation of determinants of Laplacians on compact Riemann surfaces.
Modeling the Circumstellar Disk of $\\zeta$ Tauri
Carciofi, A. C.; Bjorkman, J. E.
2004-01-01
We present a model for the disk of the classical Be star $\\zeta$ Tauri. The model consists of a Keplerian rotating disk with a power-law surface density and a vertical density distribution that follows from the balance between the thermal gas pressure and the z-component of the stellar gravitation. The opening angle of such a disk is not a fixed value but increases with the distance to the star (flared disk). We use a Monte Carlo code that solves simultaneously the thermal equilibrium, the st...
Zeta regularized products, Riemann zeta zeros and prime number spectra
Menezes, G; Svaiter, N F
2013-01-01
The Riemann hypothesis states that all nontrivial zeros of the zeta function lie in the critical line $\\Re(s)=1/2$. Hilbert and P\\'olya suggested that one possible way to prove the Riemann hypothesis is to interpret the nontrivial zeros in the light of spectral theory. Following this approach, we associate such a numerical sequence with the discrete spectrum of a linear differential operator. We discuss a necessary condition that such a sequence of numbers should obey in order to be associated with the spectrum of a linear differential operator of a system with countably infinite number of degrees of freedom. The sequence of nontrivial zeros is zeta regularizable. Then, functional integrals associated with hypothetical systems described by self-adjoint operators whose spectra is given by the sequence of the nontrivial zeros of the Riemann zeta function could be constructed. In addition, we demonstrate that if one considers the same situation with primes numbers, the associated functional integral cannot be co...
Bernoulli numbers and zeta functions
Arakawa, Tsuneo; Kaneko, Masanobu
2014-01-01
Two major subjects are treated in this book. The main one is the theory of Bernoulli numbers and the other is the theory of zeta functions. Historically, Bernoulli numbers were introduced to give formulas for the sums of powers of consecutive integers. The real reason that they are indispensable for number theory, however, lies in the fact that special values of the Riemann zeta function can be written by using Bernoulli numbers. This leads to more advanced topics, a number of which are treated in this book: Historical remarks on Bernoulli numbers and the formula for the sum of powers of consecutive integers; a formula for Bernoulli numbers by Stirling numbers; the Clausen–von Staudt theorem on the denominators of Bernoulli numbers; Kummer's congruence between Bernoulli numbers and a related theory of p-adic measures; the Euler–Maclaurin summation formula; the functional equation of the Riemann zeta function and the Dirichlet L functions, and their special values at suitable integers; various formulas of ...
Convergence of zeta functions of graphs
Clair, Bryan; Mokhtari-Sharghi, Shahriar
2000-01-01
The $L^2$-zeta function of an infinite graph Y (defined previously in a ball around zero) has an analytic extension. For a tower of finite graphs covered by Y, the normalized zeta functions of the finite graphs converge to the $L^2$-zeta function of Y.
Navakkode, Sheeja; Sajikumar, Sreedharan; Sacktor, Todd Charlton; Frey, Julietta U.
2010-01-01
Dopaminergic D1/D5-receptor-mediated processes are important for certain forms of memory as well as for a cellular model of memory, hippocampal long-term potentiation (LTP) in the CA1 region of the hippocampus. D1/D5-receptor function is required for the induction of the protein synthesis-dependent maintenance of CA1-LTP (L-LTP) through activation…
On multiple zeta values of even arguments
Energy Technology Data Exchange (ETDEWEB)
Hoffmann, Michael E. [U.S. Naval Academy, Annapolis, MD (United States). Dept. of Mathematics; Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)
2012-06-15
For k {<=} n, let E(2n,k) be the sum of all multiple zeta values with even arguments whose weight is 2n and whose depth is k. Of course E(2n,1) is the value {zeta}(2n) of the Riemann zeta function at 2n, and it is well known that E(2n,2)=(3)/(4){zeta}(2n). Recently Z. Shen and T. Cai gave formulas for E(2n,3) and E(2n,4) in terms {zeta}(2n) and {zeta}(2){zeta}(2n-2). We give two formulas form E(2n,k), both valid for arbitrary k{<=}n, one of which generalizes the Shen-Cai results; by comparing the two we obtain a Bernoulli-number identity. We also give an explicit generating function for the numbers E(2n,k).
Directory of Open Access Journals (Sweden)
Wadim Zudilin
2015-03-01
Full Text Available The multiple zeta values (MZVs possess a rich algebraic structure of algebraic relations, which is conjecturally determined by two different (shuffle and stuffle products of a certain algebra of noncommutative words. In a recent work, Bachmann constructed a q-analogue of the MZVs—the so-called bi-brackets—for which the two products are dual to each other, in a very natural way. We overview Bachmann’s construction and discuss the radial asymptotics of the bi-brackets, its links to the MZVs, and related linear (independence questions of the q-analogue.
Stable surface solitons in truncated complex potentials.
He, Yingji; Mihalache, Dumitru; Zhu, Xing; Guo, Lina; Kartashov, Yaroslav V
2012-07-01
We show that surface solitons in the one-dimensional nonlinear Schrödinger equation with truncated complex periodic potential can be stabilized by linear homogeneous losses, which are necessary to balance gain in the near-surface channel arising from the imaginary part of potential. Such solitons become stable attractors when the strength of homogeneous losses acquires values from a limited interval and they exist in focusing and defocusing media. The domains of stability of the surface solitons shrink with an increase in the amplitude of the imaginary part of complex potential.
Stable surface solitons in truncated complex potentials
He, Yingji; Zhu, Xing; Guo, Lina; Kartashov, Yaroslav V
2012-01-01
We show that surface solitons in the one-dimensional nonlinear Schr\\"odinger equation with truncated complex periodic potential can be stabilized by linear homogeneous losses, which are necessary to balance gain in the near-surface channel arising from the imaginary part of potential. Such solitons become stable attractors when the strength of homogeneous losses acquires values from a limited interval and they exist in focusing and defocusing media. The domains of stability of surface solitons shrink with increase of the amplitude of imaginary part of complex potential.
Scanning Surface Potential Microscopy of Spore Adhesion on Surfaces
Energy Technology Data Exchange (ETDEWEB)
Lee, Ida [University of Tennessee, Knoxville (UTK); Chung, Eunhyea [Georgia Institute of Technology; Kweon, Hyojin [Georgia Institute of Technology; Yiacoumi, Sotira [Georgia Institute of Technology; Tsouris, Costas [ORNL
2012-01-01
The adhesion of spores of Bacillus anthracis - the cause of anthrax and a likely biological threat - to solid surfaces is an important consideration in cleanup after an accidental or deliberate release. However, because of safety concerns, directly studying B. anthracis spores with advanced instrumentation is problematic. As a first step, we are examining the electrostatic potential of Bacillus thuringiensis (Bt), which is a closely related species that is often used as a simulant to study B. anthracis. Scanning surface potential microscopy (SSPM), also known as Kelvin probe force microscopy (KPFM), was used to investigate the influence of relative humidity (RH) on the surface electrostatic potential of Bt that had adhered to silica, mica, or gold substrates. AFM/SSPM side-by-side images were obtained separately in air, at various values of RH, after an aqueous droplet with spores was applied on each surface and allowed to dry before measurements. In the SSPM images, a negative potential on the surface of the spores was observed compared with that of the substrates. The surface potential decreased as the humidity increased. Spores were unable to adhere to a surface with an extremely negative potential, such as mica.
Tracking Surface Cyclones with Moist Potential Vorticity
Institute of Scientific and Technical Information of China (English)
Zuohao CAO; Da-Lin ZHANG
2004-01-01
Surface cyclone tracks are investigated in the context of moist potential vorticity (MPV). A prognostic equation of surface absolute vorticity is derived which provides a basis for using negative MPV (NMPV) in the troposphere as an alternative approach to track surface cyclones. An observed case study of explosive lee cyclogenesis is performed to test the effectiveness of the MPV approach. It is shown that when a surface cyclone signal is absent due to the blocking of the Rocky Mountains, the surface cyclone can be well identified by tracing the peak NMPV.
Fundamental Domains of Gamma and Zeta Functions
Directory of Open Access Journals (Sweden)
Cabiria Andreian Cazacu
2011-01-01
Full Text Available Branched covering Riemann surfaces (ℂ,f are studied, where f is the Euler Gamma function and the Riemann Zeta function. For both of them fundamental domains are found and the group of cover transformations is revealed. In order to find fundamental domains, preimages of the real axis are taken and a thorough study of their geometry is performed. The technique of simultaneous continuation, introduced by the authors in previous papers, is used for this purpose. Color visualization of the conformal mapping of the complex plane by these functions is used for a better understanding of the theory. A version of this paper containing colored images can be found in arXiv at Andrian Cazacu and Ghisa.
The triple system Zeta Aquarii
Tokovinin, Andrei
2016-01-01
Zeta Aquarii is a bright and nearby (28 pc) triple star with a 26-year astrometric subsystem. Almost a half of the outer 540-year visual orbit has been covered in 238 years of its observations. Both inner and outer orbits are revised here taking into account recent direct resolution of the inner pair Aa,Ab. The inner orbit has a high eccentricity of 0.87 and is inclined to the outer orbit by 140+-10 degrees, suggesting that Kozai-Lidov cycles take place. The masses of the stars Aa, B, and Ab are 1.4, 1.4, and 0.6 solar. The age of the system is about 3 Gyr, and the two main components have just left the main sequence. Hypothetically, this system could have formed by a dynamical capture of the small star Ab in the twin binary Aa,B.
Riemann zeta function is a fractal
Woon, S C
1994-01-01
Voronin's theorem on the "Universality" of Riemann zeta function is shown to imply that Riemann zeta function is a fractal (in the sense that Mandelbrot set is a fractal) and a concrete "representation" of the "giant book of theorems'' that Paul Halmos referred to.
Lowest Landau level on a cone and zeta determinants
Klevtsov, Semyon
2017-06-01
We consider the integer QH state on Riemann surfaces with conical singularities, with the main objective of detecting the effect of the gravitational anomaly directly from the form of the wave function on a singular geometry. We suggest the formula expressing the normalisation factor of the holomorphic state in terms of the regularized zeta determinant on conical surfaces and check this relation for some model geometries. We also comment on possible extensions of this result to the fractional QH states.
Lowest Landau level on a cone and zeta determinants
Klevtsov, Semyon
2016-01-01
We consider the integer QH state on Riemann surfaces with conical singularities, with the main objective of detecting the effect of the gravitational anomaly directly from the form of the wave function on a singular geometry. We suggest the formula expressing the normalisation factor of the holomorphic state in terms of the regularized zeta determinant on conical surfaces and check this relation for some model geometries. We also comment on possible extensions of this result to the fractional QH states.
Surface ζ potential and photocatalytic activity of rare earths doped TiO2
Institute of Scientific and Technical Information of China (English)
SONG Mianxin; BIAN Liang; ZHOU Tianliang; ZHAO Xiaoyong
2008-01-01
The iso-electric point of different rare earths (La, Ce, Y) doped anatase TiO2 was set out, and three organisms with different sur-face electrical properties (methylene blue trihydrate-positive electricity, methyl orange-negative electricity, methyl red-neutral electricity) were selected as photodegradable models. The result showed that the photocatalytic activity of 0.5wt.%Y ions doped anatase TiO2 was better than those of the others. The relationship between Zeta (ζ) potential and the photocatalytic activity of different RE doped anatase TiO2 were also investigated. The Y-doped anatase TiO2 was found with the special two iso-electric points and three ζ potential values.
Potential energy surface of alanine polypeptide chains
DEFF Research Database (Denmark)
Solov'yov, Ilia; Yakubovich, Alexander V.; Solov'yov, Andrey V.
2006-01-01
The multidimensional potential energy surfaces of the peptide chains consisting of three and six alanine (Ala) residues have been studied with respect to the degrees of freedom related to the twist of these molecules relative to the peptide backbone (these degrees of freedom are responsible...
Integrals of products of Hurwitz zeta functions
Shpot, M A; Paris, R B
2016-01-01
We evaluate two integrals over $x\\in [0,1]$ involving products of the function $\\zeta_1(a,x)\\equiv \\zeta(a,x)-x^{-a}$ for $\\Re (a)>1$, where $\\zeta(a,x)$ is the Hurwitz zeta function. The evaluation of these integrals for the particular case of integer $a\\geq 2$ is also presented. As an application we calculate the $O(g)$ weak-coupling expansion coefficient $c_{1}(\\varepsilon)$ of the Casimir energy for a film with Dirichlet-Dirichlet boundary conditions, first stated by Symanzik [Schr\\"odinger representation and Casimir effect in renormalizable quantum field theory, Nucl. Phys. B 190 (1981) 1-44] in the framework of $g\\phi^4_{4-\\varepsilon}$ theory.
Vibrational dynamics of the bifluoride ion. I. Construction of a model potential surface
Epa, V. C.; Choi, J. H.; Klobukowski, M.; Thorson, W. R.
1990-01-01
Construction of an extended model potential surface for the bifluoride ion [FHF-] is described, based on ab initio calculations for the free ion at the CID (configuration interaction, double replacement) level with a Huzinaga-Dunning double-zeta basis set. 710 data points were generated, for displacements in the three noncyclic vibrational coordinates exploring the potential surface to a height at least 30 000 cm-1 above its minimum, and giving a realistic account of the dissociation into HF+F-. Analogous calculations were made for HF and F- using the same basis. The predicted hydrogen bond energy (De) is 48.13 kcal/mol, with equilibrium F-F separation Re =4.2905 a.u., in good agreement with other recent calculations. A model potential has been constructed, based on a superposition of Morse potentials associated with each H-F distance plus a fairly structureless correction function expressible as a 36-term least-squares polynomial in the prolate spheroidal coordinates used to describe vibrational displacements. The resulting model surface fits all 710 ab initio data points with an r.m.s. deviation of 65.6 cm-1, and points less than 15 000 cm-1 above the minimum with a deviation of 26.3 cm-1. This surface provides the basis for a series of vibrational dynamics studies on the FHF- system being done in this laboratory.
Influence of surface charge on the potential toxicity of PLGA nanoparticles towards Calu-3 cells
Directory of Open Access Journals (Sweden)
Mura S
2011-10-01
Full Text Available Simona Mura1,2, Herve Hillaireau1,2, Julien Nicolas1,2, Benjamin Le Droumaguet1,2, Claire Gueutin1,2, Sandrine Zanna3, Nicolas Tsapis1,2, Elias Fattal1,2 1Univ Paris-Sud, UMR 8612, Châtenay Malabry, F-92296; 2CNRS, Châtenay Malabry, F-92296; 3Laboratoire de Physico-Chimie des Surfaces, CNRS-ENSCP (UMR 7045, Ecole Nationale Superiore de Chimie de Paris, France Background: Because of the described hazards related to inhalation of manufactured nanoparticles, we investigated the lung toxicity of biodegradable poly (lactide-co-glycolide (PLGA nanoparticles displaying various surface properties on human bronchial Calu-3 cells. Methods: Positively and negatively charged as well as neutral nanoparticles were tailored by coating their surface with chitosan, Poloxamer, or poly (vinyl alcohol, respectively. Nanoparticles were characterized in terms of size, zeta potential, and surface chemical composition, confirming modifications provided by hydrophilic polymers. Results: Although nanoparticle internalization by lung cells was clearly demonstrated, the cytotoxicity of the nanoparticles was very limited, with an absence of inflammatory response, regardless of the surface properties of the PLGA nanoparticles. Conclusion: These in vitro results highlight the safety of biodegradable PLGA nanoparticles in the bronchial epithelium and provide initial data on their potential effects and the risks associated with their use as nanomedicines. Keywords: nanoparticles, PLGA, surface properties, Calu-3, toxicity, inflammation
Computed potential energy surfaces for chemical reactions
Walch, Stephen P.
1994-01-01
Quantum mechanical methods have been used to compute potential energy surfaces for chemical reactions. The reactions studied were among those believed to be important to the NASP and HSR programs and included the recombination of two H atoms with several different third bodies; the reactions in the thermal Zeldovich mechanism; the reactions of H atom with O2, N2, and NO; reactions involved in the thermal De-NO(x) process; and the reaction of CH(squared Pi) with N2 (leading to 'prompt NO'). These potential energy surfaces have been used to compute reaction rate constants and rates of unimolecular decomposition. An additional application was the calculation of transport properties of gases using a semiclassical approximation (and in the case of interactions involving hydrogen inclusion of quantum mechanical effects).
Cai, Huihui; Fan, Hao; Zhao, Leihong; Hong, Huachang; Shen, Liguo; He, Yiming; Lin, Hongjun; Chen, Jianrong
2016-03-01
Effects of both membrane and sludge foulant surface zeta potentials on interfacial interactions between membrane and sludge foulant in different interaction scenarios were systematically investigated based on thermodynamic methods. Under conditions in this study, it was found that zeta potential had marginal effects on total interfacial interaction between two infinite planar surfaces, and the total interfacial interaction between foulant particles and membrane would be more repulsive with increase of absolute value of zeta potential. Adhesion of foulant particles on membrane surface should overcome an energy barrier. There exists a critical zeta potential below which energy barrier would disappear. Results also showed that rough surface membrane corresponded to significantly low strength of interfacial interactions. This study not only provided a series of methods to quantitatively assess the interfacial interactions between membrane and sludge foulants, but also reconciled the contradictory conclusions regarding effects of zeta potential in literature, giving important implications for membrane fouling mitigation.
Diabatic potential energy surfaces of H+ + CO
Indian Academy of Sciences (India)
F George D X; Sanjay Kumar
2007-09-01
Ab initio adiabatic and diabatic surfaces of the ground and the first excited electronic states have been computed for the H+ + CO system for the collinear ( = 0°) and the perpendicular ( = 90°) geometries employing the multi-reference configuration interaction method and Dunning's -VTZ basis set. Other properties such as mixing angle before coupling potential and before coupling matrix elements have also been obtained in order to provide an understanding of the coupling dynamics of inelastic and charge transfer process.
Riemann zeta function from wave-packet dynamics
DEFF Research Database (Denmark)
Mack, R.; Dahl, Jens Peder; Moya-Cessa, H.
2010-01-01
is governed by the temperature of the thermal phase state and tau is proportional to t. We use the JWKB method to solve the inverse spectral problem for a general logarithmic energy spectrum; that is, we determine a family of potentials giving rise to such a spectrum. For large distances, all potentials...... index of JWKB. We compare and contrast exact and approximate eigenvalues of purely logarithmic potentials. Moreover, we use a numerical method to find a potential which leads to exact logarithmic eigenvalues. We discuss possible realizations of Riemann zeta wave-packet dynamics using cold atoms...
Theoretical studies of potential energy surfaces
Energy Technology Data Exchange (ETDEWEB)
Harding, L.B. [Argonne National Laboratory, IL (United States)
1993-12-01
The goal of this program is to calculate accurate potential energy surfaces (PES) for both reactive and nonreactive systems. To do this the electronic Schrodinger equation must be solved. Our approach to this problem starts with multiconfiguration self-consistent field (MCSCF) reference wavefunctions. These reference wavefunctions are designed to be sufficiently flexible to accurately describe changes in electronic structure over a broad range of geometries. Electron correlation effects are included via multireference, singles and doubles configuration interaction (MRSDCI) calculations. With this approach, the authors are able to provide useful predictions of the energetics for a broad range of systems.
Sparse representation for a potential energy surface
Seko, Atsuto; Takahashi, Akira; Tanaka, Isao
2014-07-01
We propose a simple scheme to estimate the potential energy surface (PES) for which the accuracy can be easily controlled and improved. It is based on model selection within the framework of linear regression using the least absolute shrinkage and selection operator (LASSO) technique. Basis functions are selected from a systematic large set of candidate functions. The sparsity of the PES significantly reduces the computational cost of evaluating the energy and force in molecular dynamics simulations without losing accuracy. The usefulness of the scheme for describing the elemental metals Na and Mg is clearly demonstrated.
Fourier coefficients associated with the Riemann zeta-function
Directory of Open Access Journals (Sweden)
Y. V. Basiuk
2016-06-01
Full Text Available We study the Riemann zeta-function $\\zeta(s$ by a Fourier series method. The summation of $\\log|\\zeta(s|$ with the kernel $1/|s|^{6}$ on the critical line $\\mathrm{Re}\\; s = \\frac{1}{2}$ is the main result of our investigation. Also we obtain a new restatement of the Riemann Hypothesis.
Partial zeta functions of algebraic varieties over finite fields
Wan, D
2000-01-01
By restricting the variables running over various (possibly different) subfields, we introduce the notion of a partial zeta function. We prove that the partial zeta function is rational in an interesting case, generalizing Dwork's well known rationality theorem. In general, the partial zeta function is probably not rational. But a theorem of Faltings says that the partial zeta function is always nearly rational.
Zeta functions in brane world cosmology
Flachi, Antonino; Knapman, Alan; Naylor, Wade; Sasaki, Misao
2004-12-01
We present a calculation of the zeta function and of the functional determinant for a Laplace-type differential operator, corresponding to a scalar field in a higher-dimensional deSitter brane background, which consists of a higher-dimensional anti deSitter bulk spacetime bounded by a deSitter section, representing a brane. Contrary to the existing examples, which all make use of conformal transformations, we evaluate the zeta function working directly with the higher-dimensional wave operator. We also consider a generic mass term and coupling to curvature, generalizing previous results. The massless, conformally coupled case is obtained as a limit of the general result and compared with known calculations. In the limit of large anti deSitter radius, the zeta determinant for the ball is recovered in perfect agreement with known expressions, providing an interesting check of our result and an alternative way of obtaining the ball determinant.
Directory of Open Access Journals (Sweden)
Mahe YF
2013-08-01
Full Text Available Yann F Mahe,1 Marie-Jesus Perez,1 Charlotte Tacheau,1 Chantal Fanchon,2 Richard Martin,3 Françoise Rousset,1 Sophie Seite4 1L’Oreal Research and Innovation, Clichy, 2L’Oréal Research and Innovation, Chevilly Larue, 3L’Oréal Research and Innovation Tours, 4La Roche-Posay Pharmaceutical Laboratories, Asnières, France Abstract: Vitreoscilla filiformis (VF biomass (VFB has been widely used in cosmetic preparations and shown to modulate the major inducible free-radical scavenger mitochondrial superoxide dismutase in skin cells. By adding La Roche-Posay (LRP thermal spring water to the VF culture medium, we obtained a biomass (LRP-VFB with a similar mitochondrial superoxide dismutase activation capacity to VF. Also, the new biomass more powerfully stimulated mRNA expression and antimicrobial peptides in reconstructed epidermis. Interestingly, a predictive computer model that analyzed transducing events within skin epidermal cells suggested that this protective activity may involve the Toll-like receptor 2/protein kinase C, zeta transduction pathway. Protein kinase C, zeta inhibition was effectively shown to abolish VFB-induced gene stimulation and confirmed this hypothesis. This thus opens new avenues for investigation into the improvement of skin homeostatic defense in relation to the control of its physiological microbiota and innate immunity. Keywords: innate skin defenses, TLR2, PKCz, La Roche-Posay, mitochondrial superoxide dismutase, SOD2
Zeta Functions Of Discrete Groups Acting On Trees
Clair, Bryan; Mokhtari-Sharghi, Shahriar
1999-01-01
This paper generalizes Bass' work on zeta functions for uniform tree lattices. Using the theory of von Neumann algebras, machinery is developed to define the zeta function of a discrete group of automorphisms of a bounded degree tree. The main theorems relate the zeta function to determinants of operators defined on edges or vertices of the tree. A zeta function associated to a non-uniform tree lattice with appropriate Hilbert representation is defined. Zeta functions are defined for infinite...
Potential energy surface of triplet N{sub 2}O{sub 2}
Energy Technology Data Exchange (ETDEWEB)
Varga, Zoltan; Meana-Pañeda, Rubén; Song, Guoliang; Paukku, Yuliya; Truhlar, Donald G., E-mail: truhlar@umn.edu [Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431 (United States)
2016-01-14
We present a global ground-state triplet potential energy surface for the N{sub 2}O{sub 2} system that is suitable for treating high-energy vibrational-rotational energy transfer and collision-induced dissociation. The surface is based on multi-state complete-active-space second-order perturbation theory/minimally augmented correlation-consistent polarized valence triple-zeta electronic structure calculations plus dynamically scaled external correlation. In the multireference calculations, the active space has 14 electrons in 12 orbitals. The calculations cover nine arrangements corresponding to dissociative diatom-diatom collisions of N{sub 2}, O{sub 2}, and nitric oxide (NO), the interaction of a triatomic molecule (N{sub 2}O and NO{sub 2}) with the fourth atom, and the interaction of a diatomic molecule with a single atom (i.e., the triatomic subsystems). The global ground-state potential energy surface was obtained by fitting the many-body interaction to 54 889 electronic structure data points with a fitting function that is a permutationally invariant polynomial in terms of bond-order functions of the six interatomic distances.
Euler Polynomials, Fourier Series and Zeta Numbers
DEFF Research Database (Denmark)
Scheufens, Ernst E
2012-01-01
Fourier series for Euler polynomials is used to obtain information about values of the Riemann zeta function for integer arguments greater than one. If the argument is even we recover the well-known exact values, if the argument is odd we find integral representations and rapidly convergent series....
The magnetic field of zeta Orionis A
Blazère, A; Tkachenko, A; Bouret, J -C; Rivinius, Th
2015-01-01
Zeta Ori A is a hot star claimed to host a weak magnetic field, but no clear magnetic detection was obtained so far. In addition, it was recently shown to be a binary system composed of a O9.5I supergiant and a B1IV star. We aim at verifying the presence of a magnetic field in zeta Ori A, identifying to which of the two binary components it belongs (or whether both stars are magnetic), and characterizing the field.Very high signal-to-noise spectropolarimetric data were obtained with Narval at the Bernard Lyot Telescope (TBL) in France. Archival HEROS, FEROS and UVES spectroscopic data were also used. The data were first disentangled to separate the two components. We then analyzed them with the Least-Squares Deconvolution (LSD) technique to extract the magnetic information. We confirm that zeta Ori A is magnetic. We find that the supergiant component zeta Ori Aa is the magnetic component: Zeeman signatures are observed and rotational modulation of the longitudinal magnetic field is clearly detected with a per...
Euler Polynomials, Fourier Series and Zeta Numbers
DEFF Research Database (Denmark)
Scheufens, Ernst E
2012-01-01
Fourier series for Euler polynomials is used to obtain information about values of the Riemann zeta function for integer arguments greater than one. If the argument is even we recover the well-known exact values, if the argument is odd we find integral representations and rapidly convergent series....
Bernoulli Polynomials, Fourier Series and Zeta Numbers
DEFF Research Database (Denmark)
Scheufens, Ernst E
2013-01-01
Fourier series for Bernoulli polynomials are used to obtain information about values of the Riemann zeta function for integer arguments greater than one. If the argument is even we recover the well-known exact values, if the argument is odd we find integral representations and rapidly convergent ...
Zeta and q-Zeta Functions and Associated Series and Integrals
Srivastava, H M
2011-01-01
Zeta and q-Zeta Functions and Associated Series and Integrals is a thoroughly revised, enlarged and updated version of Series Associated with the Zeta and Related Functions. Many of the chapters and sections of the book have been significantly modified or rewritten and a new chapter on the theory and applications of the basic (or q-) extensions of various Special Functions is included. This book will be invaluable as it covers not only detailed and systematic presentations of the theory and applications of the various methods and techniques used in dealing with many different classes of ser
Energy conservation potential of surface modification technologies
Energy Technology Data Exchange (ETDEWEB)
Le, H.K.; Horne, D.M.; Silberglitt, R.S.
1985-09-01
This report assesses the energy conservation impact of surface modification technologies on the metalworking industries. The energy conservation impact of surface modification technologies on the metalworking industries is assessed by estimating their friction and wear tribological sinks and the subsequent reduction in these sinks when surface modified tools are used. Ion implantation, coatings, and laser and electron beam surface modifications are considered.
Adiabatic density surface, neutral density surface, potential density surface, and mixing path
Institute of Scientific and Technical Information of China (English)
HUANG Rui-xin
2014-01-01
In this paper, adiabatic density surface, neutral density surface and potential density surface are compared. The adiabatic density surface is defined as the surface on which a water parcellcan move adiabatically, without changing its potential temperature and salinity. For a water parcelltaken at a given station and pressure level, the corresponding adiabatic density surface can be determined through simple calculations. This family of surface is neutrally buoyant in the world ocean, and different from other surfaces that are not truly neutrally buoyant. In order to explore mixing path in the ocean, a mixing ratio m is introduced, which is defined as the portion of potential temperature and salinity of a water parcellthat has exchanged with the environment during a segment of migration in the ocean. Two extreme situations of mixing path in the ocean are m=0 (no mixing), which is represented by the adiabatic density curve, and m=1, where the original information is completely lost through mixing. The latter is represented by the neutral density curve. The reality lies in between, namely, 0
Potential energy surface and rovibrational energy levels of the H2-CS van der Waals complex.
Denis-Alpizar, Otoniel; Stoecklin, Thierry; Halvick, Philippe; Dubernet, Marie-Lise; Marinakis, Sarantos
2012-12-21
Owing to its large dipole, astrophysicists use carbon monosulfide (CS) as a tracer of molecular gas in the interstellar medium, often in regions where H(2) is the most abundant collider. Predictions of the rovibrational energy levels of the weakly bound complex CS-H(2) (not yet observed) and also of rate coefficients for rotational transitions of CS in collision with H(2) should help to interpret the observed spectra. This paper deals with the first goal, i.e., the calculation of the rovibrational energy levels. A new four-dimensional intermolecular potential energy surface for the H(2)-CS complex is presented. Ab initio potential energy calculations were carried out at the coupled-cluster level with single and double excitations and a perturbative treatment of triple excitations, using a quadruple-zeta basis set and midbond functions. The potential energy surface was obtained by an analytic fit of the ab initio data. The equilibrium structure of the H(2)-CS complex is found to be linear with the carbon pointing toward H(2) at the intermolecular separation of 8.6 a(o). The corresponding well depth is -173 cm(-1). The potential was used to calculate the rovibrational energy levels of the para-H(2)-CS and ortho-H(2)-CS complexes. The present work provides the first theoretical predictions of these levels. The calculated dissociation energies are found to be 35.9 cm(-1) and 49.9 cm(-1), respectively, for the para and ortho complexes. The second virial coefficient for the H(2)-CS pair has also been calculated for a large range of temperature. These results could be used to assign future experimental spectra and to check the accuracy of the potential energy surface.
The weak magnetic field of the O9.7 supergiant zeta Orionis A
Bouret, J -C; Martins, F; Escolano, C; Marcolino, W; Lanz, T; Howarth, Ian
2008-01-01
We report here the detection of a weak magnetic field of 50 - 100 G on the O9.7 supergiant zeta Ori A, using spectropolarimetric observations obtained with NARVAL at the 2m Telescope Bernard Lyot atop Pic du Midi (France). zeta Ori A is the third O star known to host a magnetic field (along with theta^1 Ori C and HD 191612), and the first detection on a 'normal' rapidly-rotating O star. The magnetic field of zeta Ori A is the weakest magnetic field ever detected on a massive star. The measured field is lower than the thermal equipartition limit (about 100 G). By fitting NLTE model atmospheres to our spectra, we determined that zeta Ori A is a 40 Msun star with a radius of 25 Rsun and an age of about 5 - 6 Myr, showing no surface nitrogen enhancement and losing mass at a rate of about 2x10^(-6) Msol/yr. The magnetic topology of zeta Ori A is apparently more complex than a dipole and involves two main magnetic polarities located on both sides of the same hemisphere; our data also suggest that zeta Ori A rotates...
Special Uniformity of Zeta Functions I. Geometric Aspect
Weng, Lin
2012-01-01
The special uniformity of zeta functions claims that pure non-abelian zeta functions coincide with group zeta functions associated to the special linear groups. Naturally associated are three aspects, namely, the analytic, arithmetic, and geometric aspects. In the first paper of this series, we expose intrinsic geometric structures of our zetas by counting semi-stable bundles on curves defined over finite fields in terms of their automorphism groups and global sections. We show that such a counting maybe read from Artin zetas which are abelian in nature. This paper also contains an appendix written by H. Yoshida, one of the driving forces for us to seek group zetas. In this appendix, Yoshida introduces a new zeta as a function field analogue of the group zeta for SL2 for number fields and establishes the Riemann Hypothesis for it.
Graph Zeta function and gauge theories
He, Yang-Hui
2011-03-01
Along the recently trodden path of studying certain number theoretic properties of gauge theories, especially supersymmetric theories whose vacuum manifolds are non-trivial, we investigate Ihara's Graph Zeta Function for large classes of quiver theories and periodic tilings by bi-partite graphs. In particular, we examine issues such as the spectra of the adjacency and whether the gauge theory satisfies the strong and weak versions of the graph theoretical analogue of the Riemann Hypothesis.
Computing zeta functions of sparse nondegenerate hypersurfaces
Sperber, Steven
2011-01-01
Using the cohomology theory of Dwork, as developed by Adolphson and Sperber, we exhibit a deterministic algorithm to compute the zeta function of a nondegenerate hypersurface defined over a finite field. This algorithm is particularly well-suited to work with polynomials in small characteristic that have few monomials (relative to their dimension). Our method covers toric, affine, and projective hypersurfaces and also can be used to compute the L-function of an exponential sum.
Zeta-functions of renormalizable sub-Lorenz templates
Energy Technology Data Exchange (ETDEWEB)
Franco, Nuno, E-mail: nmf@uevora.p [CIMA-UE and Department of Mathematics, University of Evora, Rua Romao Ramalho, 59, 7000-671 Evora (Portugal); Silva, Luis, E-mail: lfs@dec.isel.ipl.p [CIMA-UE and Scientific Area of Mathematics, Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Emidio Navarro, 1, 1959-007 Lisboa (Portugal)
2010-12-15
We describe the Williams zeta-functions and the twist zeta-functions of sub-Lorenz templates generated by renormalizable Lorenz maps, in terms of the corresponding zeta-functions of the sub-Lorenz templates generated by the renormalized map and by the map that determines the renormalization type.
Urban Surfaces and Heat Island Mitigation Potentials
Energy Technology Data Exchange (ETDEWEB)
Akbari, Hashem; Akbari, Hashem; Shea Rose, Leanna
2007-06-14
Data on materials and surface types that comprise a city, i.e. urban fabric, are needed in order to estimate the effects of light-colored surfaces (roofs and pavements) and urban vegetation (trees, grass, shrubs) on the meteorology and air quality of a city. We discuss the results of a semi-automatic statistical approach used to develop data on surface-type distribution and urban-fabric makeup using aerial color orthophotography, for four metropolitan areas of Chicago, IL, Houston, TX, Sacramento, CA, and Salt Lake City, UT. The digital high resolution (0.3 to 0.5-m) aerial photographs for each of these metropolitan areas covers representative urban areas ranging from 30 km{sup 2} to 52 km{sup 2}. Major land-use types examined included: commercial, residential, industrial, educational, and transportation. On average, for the metropolitan areas studied, vegetation covers about 29-41% of the area, roofs 19-25%, and paved surfaces 29-39%. For the most part, trees shade streets, parking lots, grass, and sidewalks. At ground level, i.e., view from below the tree canopies, vegetation covers about 20-37% of the area, roofs 20-25%, and paved surfaces 29-36%.
Energy Technology Data Exchange (ETDEWEB)
Tsai, Chia-Chang; Chiang, Pei-Ling; Lin, Tsung-Wu; Chen, Yit-Tsong [Institute of Atomic and Molecular Sciences, Academia Sinica, PO Box 23-166, Taipei 106, Taiwan (China); Sun, Chih-Jung; Tsai, Ming-Hsueh [Department of Chemistry, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 106, Taiwan (China); Chang, Yun-Chorng, E-mail: ychang6@mail.ncku.edu.tw, E-mail: ytcchem@ntu.edu.tw [Institute of Electro-Optical Science and Engineering, National Cheng Kung University, No. 1, Ta-Hsueh Road, Tainan 701, Taiwan (China)
2011-04-01
Using a silicon nanowire field-effect transistor (SiNW-FET) for biomolecule detections, we selected 3-(mercaptopropyl)trimethoxysilane (MPTMS), N-[6-(biotinamido)hexyl]-3{sup '}-(2{sup '}-pyridyldithio) propionamide (biotin-HPDP), and avidin, respectively, as the designated linker, receptor, and target molecules as a study model, where the biotin molecules were modified on the SiNW-FET to act as a receptor for avidin. We applied high-resolution scanning Kelvin probe force microscopy (KPFM) to detect the modified/bound biomolecules by measuring the induced change of the surface potential ({Delta}{Phi}{sup s}) on the SiNW-FET under ambient conditions. After biotin-immobilization and avidin-binding, the {Delta}{Phi}{sup s} on the SiNW-FET characterized by KPFM was demonstrated to correlate to the conductance change inside the SiNW-FET acquired in aqueous solution. The {Delta}{Phi}{sup s} values on the SiNW-FET caused by the same biotin-immobilization and avidin-binding were also measured from drain current versus gate voltage curves (I{sub d}-V{sub g}) in both aqueous condition and dried state. For comparison, we also study the {Delta}{Phi}{sup s} values on a Si wafer caused by the same biotin-immobilization and avidin-binding through KPFM and {zeta} potential measurements. This study has demonstrated that the surface potential measurement on a SiNW-FET by KPFM can be applied as a diagnostic tool that complements the electrical detection with a SiNW-FET sensor. Although the KPFM experiments were carried out under ambient conditions, the measured surface properties of a SiNW-FET are qualitatively valid compared with those obtained by other biosensory techniques performed in liquid environment.
Hydrophobic and electrostatic cell surface properties of Cryptosporidium parvum.
Drozd, C; Schwartzbrod, J
1996-01-01
Microbial adhesion to hydrocarbons and microelectrophoresis were investigated in order to characterize the surface properties of Cryptosporidium parvum. Oocysts exhibited low removal rates by octane (only 20% on average), suggesting that the Cryptosporidium sp. does not demonstrate marked hydrophobic properties. A zeta potential close to -25 mV at pH 6 to 6.5 in deionized water was observed for the parasite. Measurements of hydrophobicity and zeta potential were performed as a function of pH ...
Omidvar, Zahra; Parivar, Kazem; Sanee, Hamideh; Amiri-Tehranizadeh, Zeinab; Baratian, Ali; Saberi, Mohammad Reza; Asoodeh, Ahmad; Chamani, Jamshidkhan
2011-08-01
orientation. The potential at the electrokinetic shear surface of the protein-drug solution were measured at several concentrations of the drugs by the ζ potential technique, which confirmed experimental and theoretical results.
POLES OF ZETA FUNCTIONS OF COMPLETE INTERSECTIONS
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
A vanishing theorem is proved for -adic cohomology with compact support on an affine (singular) complete intersection. As an application, it is shown that for an affine complete intersection defined over a finite field of q elements, the reciprocal "poles" of the zeta function are always divisible by q as algebraic integers. A p-adic proof is also given, which leads to further q-divisibility of the poles or equivalently an improvement of the polar part of the AxKatz theorem for an affine complete intersection. Similar results hold for a projective complete intersection.
Dedekind zeta-functions and Dedekind sums
Institute of Scientific and Technical Information of China (English)
陆洪文; 焦荣政; 纪春岗
2002-01-01
In this paper we use Dedekind zeta functions of two real quadratic number fields at -1 to denote Dedekind sums of high rank. Our formula is different from that of Siegel's. As an application, we get a polynomial representation of ζK(-1): ζK(-1) =1/45(26n3-41n±9), n ≡±2(mod 5), where K=Q( q),prime q=4n2+1, and the class number of quadratic number field K2=Q(q) is 1.
Zeta function factorisation, Dwork hypersurfaces, hypergeometric hypersurfaces
Goutet, Philippe
2009-01-01
Let $\\mathbb{F}_q$ be a finite field with $q$ elements, $\\psi$ a non-zero element of $\\mathbb{F}_q$, and $n$ an integer $\\geq 3$ prime to $q$. The aim of this article is to show that the zeta function of the projective variety over $\\mathbb{F}_q$ defined by $X_\\psi \\colon x_1^n+...+x_n^n - n \\psi x_1... x_n=0$ has, when $n$ is prime and $X_\\psi$ is non singular (i.e. when $\\psi^n \
Ten physical applications of spectral zeta functions
Elizalde, Emilio
1995-01-01
Zeta-function regularization is a powerful method in perturbation theory. This book is meant as a guide for the student of this subject. Everything is explained in detail, in particular the mathematical difficulties and tricky points, and several applications are given to show how the procedure works in practice (e.g. Casimir effect, gravity and string theory, high-temperature phase transition, topological symmetry breaking). The formulas some of which are new can be used for accurate numerical calculations. The book is to be considered as a basic introduction and a collection of exercises for those who want to apply this regularization procedure in practice.
Los Zetas and Proprietary Radio Network Development
Directory of Open Access Journals (Sweden)
James Halverson
2016-03-01
Full Text Available The years from 2006 through 2011 were very active years for a number of Mexican drug trafficking organizations. However, the group that probably saw the most meteoric rise in this period, Los Zetas, had a unique and innovative tool at their disposal. It was during these years that the group constructed and utilized a proprietary encrypted radio network that grew to span from Texas to Guatemala through the Gulf States of Mexico and across much of the rest of the country. This network gave the group an operational edge. It also stood as a symbol of the latitude the group enjoyed across vast areas, as this extensive illicit infrastructure stood, in the face of the government and rival cartels, for six years. This investigation explicates the process by which Los Zetas constructed, concealed and utilized this network and attempts to draw conclusions about the motivations and organizational dynamics that brought the network to be, with attention paid to what this case says about the complex engineering capabilities of non-state entities in general.
Zeta functions and regularized determinants related to the Selberg trace formula
DEFF Research Database (Denmark)
Momeni, Arash; Venkov, Alexei
For a general Fuchsian group of the first kind with an arbitrary unitary representation we define the zeta functions related to the contributions of the identity, hyperbolic, elliptic and parabolic conjugacy classes in Selberg's trace formula. We present Selberg's zeta function in terms of a regu......For a general Fuchsian group of the first kind with an arbitrary unitary representation we define the zeta functions related to the contributions of the identity, hyperbolic, elliptic and parabolic conjugacy classes in Selberg's trace formula. We present Selberg's zeta function in terms...... determinants of one dimensional Schroedinger operator for harmonic oscillator. We decompose the determinant of the automorphic Laplacian into a product of the determinants where each factor is a determinant representation of a zeta function related to Selberg's trace formula. Then we derive an identity...... connecting the determinants of the automorphic Laplacians on different Riemannian surfaces related to the arithmetical groups. Finally, by using the Jacquet-Langlands correspondence we connect the determinant of the automorphic Laplacian for the unit group of quaternions to the product of the determinants...
Joni, I. Made; Zannuary, Ilham; Hidayat, Darmawan; Panatarani, Camellia
2016-02-01
This paper report the development of a simple sedimentation potential measurement system to know the state of nanoparticles (NPs) dispersion stability. The state of nanoparticles dispersion stability is very important in applications of nanoparticles since the nature of NPs is easily agglomerate. The developed sedimentation potential consist of graphite electrodes, signal conditioning, microcontroller, and interface circuits provided with a data acquisition applications. The system was designed to obtained sedimentation potential in the range -200 to 200 mV with accuracy of 0.415 mV. From the measured sedimentation potential, the zeta potential can be determined. This system was applied to investigate stability of TiO2 NPS suspension in water media to obtain the performances of the system. Those zeta potentials were determined at various condition such as vary in surface charges by controlling the pH of the suspension, vary in suspension concentrations and sedimentation time. The results show that the higher concentration of the suspension, lower zeta potential of the suspension was obtained. The zeta potential was decreased by the sedimentation time indicated that the agglomeration of particles occurred. Controlling of surface charges by controlling pH also affect the values of obtained zeta potentials. It is concluded that the developed sedimentation potential measurement successfully applied for determination of zeta potential of the TiO2 NPs suspension to evaluate the stability NPs suspension.
Green's functions potential fields on surfaces
Melnikov, Yuri A
2017-01-01
This book is comprehensive in its classical mathematical physics presentation, providing the reader with detailed instructions for obtaining Green's functions from scratch. Green's functions is an instrument easily accessible to practitioners who are engaged in design and exploitation of machines and structures in modern engineering practice. To date, there are no books available on the market that are devoted to the Green's function formalism for equations covered in this volume. The reader, with an undergraduate background in applied mathematics, can become an active user of the Green's function approach. For the first time, Green's functions are discussed for a specific class of problems dealing with potential fields induced in thin-wall structures and therefore, the reader will have first-hand access to a novel issue. This Work is accessible to researchers in applied mathematics, mechanics, and relevant disciplines such as engineering, as well as to upper level undergraduates and graduate students.
Potential energy surfaces of Polonium isotopes
Nerlo-Pomorska, B.; Pomorski, K.; Schmitt, C.; Bartel, J.
2015-11-01
The evolution of the potential energy landscape is analysed in detail for ten even-even polonium isotopes in the mass range 188\\lt A\\lt 220 as obtained within the macroscopic-microscopic approach, relying on the Lublin-Strasbourg drop model and the Yukawa-folded single-particle energies for calculating the microscopic shell and pairing corrections. A variant of the modified Funny-Hills nuclear shape parametrization is used to efficiently map possible fission paths. The approach explains the main features of the fragment partition as measured in low-energy fission along the polonium chain. The latter lies in a transitional region of the nuclear chart, and will be essential to consistently understand the evolution of fission properties from neutron-deficient mercury to heavy actinides. The ability of our method to predict fission observables over such an extended region looks promising.
Zeta Functions and the Casimir Energy
Blau, Steven K; Wipf, Andreas; 10.1016/0550-3213(88)90059-4
2009-01-01
We use zeta function techniques to give a finite definition for the Casimir energy of an arbitrary ultrastatic spacetime with or without boundaries. We find that the Casimir energy is intimately related to, but not identical to, the one-loop effective energy. We show that in general the Casimir energy depends on a normalization scale. This phenomenon has relevance to applications of the Casimir energy in bag models of QCD. Within the framework of Kaluza-Klein theories we discuss the one-loop corrections to the induced cosmological and Newton constants in terms of a Casimir like effect. We can calculate the dependence of these constants on the radius of the compact dimensions, without having to resort to detailed calculations.
Leble, Sergey
2011-01-01
One-dimensional Yang-Mills-Nahm models are considered from algebrogeometric points of view. A quasiclassical quantization of the models based on path integral and its zeta function representation in terms of a Green function diagonal for a heat equation with an elliptic potential is considered. The Green function diagonal and, hence, zeta function and its derivative are expressed via solutions of Hermit equation and, alternatively, by means of Its-Matveev formalism in terms of Riemann teta-functions. For the Nahm model, which field is represented via elliptic (lemniscate) integral by construction, one-loop quantum corrections to action are evaluated as the zeta function derivative in zero point in terms of a hyperelliptic integral. The alternative expression should help to link the representations and continue investigation of the Yang-Mills-Nahm models. Keywords: Nahm model, one-loop quantum corrections, zeta function, elliptic potential, hyperelliptic integral, Its-Matveev formula. MSC numbers: 81Q30, 35J10...
The multiple zeta value data mine
Energy Technology Data Exchange (ETDEWEB)
Buemlein, J. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Broadhurst, D.J. [Open Univ., Milton Keynes (United Kingdom). Physics and Astronomy Dept.; Vermaseren, J.A.M. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); NIKHEF, Amsterdam (Netherlands)
2009-07-15
We provide a data mine of proven results for multiple zeta values (MZVs) of the form {zeta}(s{sub 1},s{sub 2},..,s{sub k}) = sum {sup {infinity}}{sub n{sub 1}}{sub >n{sub 2}}{sub >...>n{sub k}}{sub >0} {l_brace}1/(n{sub 1}{sup s{sub 1}}..n{sub k}{sup s{sub k}}){r_brace} with weight w = sum {sup K}{sub i=1}s{sub i} and depth k and for Euler sums of the form sum {sup {infinity}}{sub n{sub 1}}{sub >n{sub 2}}{sub >...>n{sub k}}{sub >0} {l_brace}({epsilon}{sub 1}{sup n{sub 1}}..{epsilon}{sub 1}{sup n{sub k}})/(n{sub 1}{sup s{sub 1}}..n{sub k}{sup s{sub k}}){r_brace} with signs {epsilon}{sub i} = {+-} 1. Notably, we achieve explicit proven reductions of all MZVs with weights w{<=}22, and all Euler sums with weights w{<=}12, to bases whose dimensions, bigraded by weight and depth, have sizes in precise agreement with the Broadhurst. Kreimer and Broadhurst conjectures. Moreover, we lend further support to these conjectures by studying even greater weights (w{<=}30), using modular arithmetic. To obtain these results we derive a new type of relation for Euler sums, the Generalized Doubling Relations. We elucidate the ''pushdown'' mechanism, whereby the ornate enumeration of primitive MZVs, by weight and depth, is reconciled with the far simpler enumeration of primitive Euler sums. There is some evidence that this pushdown mechanism finds its origin in doubling relations. We hope that our data mine, obtained by exploiting the unique power of the computer algebra language FORM, will enable the study of many more such consequences of the double-shuffle algebra of MZVs, and their Euler cousins, which are already the subject of keen interest, to practitioners of quantum field theory, and to mathematicians alike. (orig.)
Effect of electric potential and heating on surface of KCI
Institute of Scientific and Technical Information of China (English)
无
2005-01-01
@@ The purpose of the work is research of morphology of structural changes of a surface { 100} crystals KCl under action of heating and electric field potential enclosed to one of fasets of a crystal.
Effect of electric potential and heating on surface of KCI
Institute of Scientific and Technical Information of China (English)
Feodorov; Victor; A.; Sterelukhin; Andrey; A.; Karyev; Leonid; G.
2005-01-01
The purpose of the work is research of morphology of structural changes of a surface { 100} crystals KCl under action of heating and electric field potential enclosed to one of fasets of a crystal.……
Determination of Land Surface Temperature (LST) and Potential ...
African Journals Online (AJOL)
Determination of Land Surface Temperature (LST) and Potential Urban Heat Island Effect in Parts of Lagos State using Satellite ... Changes in temperature appear to be closely related to concentrations of atmospheric carbon dioxide.
A pseudo zeta function and the distribution of primes.
Chernoff, P R
2000-07-05
The Riemann zeta function is given by: [equation, see published text]. Zeta(s) may be analytically continued to the entire s-plane, except for a simple pole at s = 0. Of great interest are the complex zeros of zeta(s). The Riemann hypothesis states that the complex zeros all have real part 1/2. According to the prime number theorem, pn approximately n logn, where pn is the nth prime. Suppose that pn were exactly nlogn. In other words, in the Euler product above, replace the nth prime by nlogn. In this way, we define a pseudo zeta function C(s) for Re s > 1. One can show that C(s) may be analytically continued at least into the half-plane Re s > 0 except for an isolated singularity (presumably a simple pole) at s = 0. It may be shown that the pseudo zeta function C(s) has no complex zeros whatsoever. This means that the complex zeros of the zeta function are associated with the irregularity of the distribution of the primes.
Shimoaka, Takafumi; Tanaka, Yuki; Shioya, Nobutaka; Morita, Kohei; Sonoyama, Masashi; Amii, Hideki; Takagi, Toshiyuki; Kanamori, Toshiyuki; Hasegawa, Takeshi
2016-12-01
A discriminative study of a single perfluoroalkyl (Rf) group from a bulk material is recently recognized to be necessary toward the total understanding of Rf compounds based on a primary chemical structure. The single molecule and the bulk matter have an interrelationship via an intrinsic two-dimensional (2D) aggregation property of an Rf group, which is theorized by the stratified dipole-arrays (SDA) theory. Since an Rf group has dipole moments along many C-F bonds, a single Rf group would possess a hydrophilic-like character on the surface. To reveal the hydration character of a single Rf group, in the present study, surface potential (ΔV) measurements are performed for Langmuir monolayers of Rf-containing compounds. From a comparative study with a monolayer of a normal hydrocarbon compound, the hydration/dehydration dynamics of a lying Rf group on water has first been monitored by ΔV measurements, through which a single Rf group has been revealed to have a unique "dipole-interactive" character, which enables the Rf group interacted with the water 'surface.' In addition, the SDA theory proves to be useful to predict the 2D aggregation property across the phase transition temperature of 19°C by use of the ΔV measurements.
Zeta Functions for Elliptic Curves I. Counting Bundles
Weng, Lin
2012-01-01
To count bundles on curves, we study zetas of elliptic curves and their zeros. There are two types, i.e., the pure non-abelian zetas defined using moduli spaces of semi-stable bundles, and the group zetas defined for special linear groups. In lower ranks, we show that these two types of zetas coincide and satisfy the Riemann Hypothesis. For general cases, exposed is an intrinsic relation on automorphism groups of semi-stable bundles over elliptic curves, the so-called counting miracle. All this, together with Harder-Narasimhan, Desale-Ramanan and Zagier's result, gives an effective way to count semi-stable bundles on elliptic curves not only in terms of automorphism groups but more essentially in terms of their $h^0$'s. Distributions of zeros of high rank zetas are also discussed.
On $p$-adic Hurwitz-type Euler zeta functions
Kim, Min-Soo
2010-01-01
Henri Cohen and Eduardo Friedman constructed the $p$-adic analogue for Hurwitz zeta functions, and Raabe-type formulas for the $p$-adic gamma and zeta functions from Volkenborn integrals satisfying the modified difference equation. In this paper, we define the $p$-adic Hurwitz-type Euler zeta functions. Our main tool is the fermionic $p$-adic integral on $\\mathbb Z_p$. We find that many interesting properties for the $p$-adic Hurwitz zeta functions are also hold for the $p$-adic Hurwitz-type Euler zeta functions, including the convergent Laurent series expansion, the distribution formula, the functional equation, the reflection formula, the derivative formula, the $p$-adic Raabe formula and so on.
Permeability dependence of streaming potential coefficient in porous media
L.D. Thanh; R. Sprik
2015-01-01
In theory, the streaming potential coefficient depends not only on the zeta potential but also on the permeability of the rocks that partially determines the surface conductivity of the rocks. However, in practice, it is hard to show the permeability dependence of streaming potential coefficients be
Permeability dependence of streaming potential coefficient in porous media
Thanh, L.D.; Sprik, R.
2015-01-01
In theory, the streaming potential coefficient depends not only on the zeta potential but also on the permeability of the rocks that partially determines the surface conductivity of the rocks. However, in practice, it is hard to show the permeability dependence of streaming potential coefficients
Osteogenic potential of laser modified and conditioned titanium zirconium surfaces
Directory of Open Access Journals (Sweden)
P David Charles
2016-01-01
Full Text Available Statement of Problem: The osseointegration of dental implant is related to their composition and surface treatment. Titanium zirconium (TiZr has been introduced as an alternative to the commercially pure titanium and its alloys as dental implant material, which is attributed to its superior mechanical and biological properties. Surface treatments of TiZr have been introduced to enhance their osseointegration ability; however, reliable, easy to use surface modification technique has not been established. Purpose: The purpose of this study was to evaluate and compare the effect of neodymium-doped yttrium aluminum garnet (Nd-YAG laser surface treatment of TiZr implant alloy on their osteogenic potential. Materials and Methods: Twenty disc-shaped samples of 5 mm diameter and 2 mm height were milled from the TiZr alloy ingot. The polished discs were ultrasonically cleaned in distilled water. Ten samples each were randomly selected as Group A control samples and Group B consisted of Nd-YAG laser surface etched and conditioned test samples. These were evaluated for cellular response. Cellular adhesion and proliferation were quantified, and the results were statistically analyzed using nonparametric analysis. Cellular morphology was observed using electron and epiflurosence microscopy. Results: Nd-YAG laser surface modified and conditioned TiZr samples increased the osteogenic potential. Conclusion: Nd-YAG laser surface modification of TiZr, improves the cellular activity, surface roughness, and wettability, thereby increasing the osteogenic potential.
Gerzhova, Alina; Mondor, Martin; Benali, Marzouk; Aider, Mohammed
2016-06-15
Total dry matter and proteins were differentially and preferentially extracted from canola meal (CM) under different conditions. The effect of the extraction medium pH, CM concentration and salt concentrations were found to have different influences on the extractability of total dry matter and proteins from CM. The pH of the extracting medium had the most significant effect. The maximal total dry matter (42.8±1.18%) extractability was obtained with 5% CM at pH 12 without salt addition, whereas the maximal for total protein (58.12±1.47%) was obtained with 15% CM under the same conditions. The minimal extractability for the dry matter (26.63±0.67%) was obtained with 5% CM at pH 10 without salt added and the minimal protein extractability was observed in a 10% CM at pH 10, in 0.01 NaCl. Turbidity and ζ-potential measurements indicated that pH 5 was the optimum condition for the highest protein extraction yield. SDS-PAGE analysis showed that salt addition contributes to higher solubility of canola proteins specifically cruciferin fraction, although it reduces napin extraction.
López-García, M. A.; López-Santiago, J. L.; Albacete-Colombo, J. F.; De Castro, E.
2013-05-01
Nearby star-forming regions are ideal laboratories to study high-energy emission processes but they usually present high absorption what makes difficult to detect the stellar population inside the molecular complex. As young late-type stars show high X-ray emission and X-ray photons are little absorbed by interstellar material, X-ray dedicated surveys are an excellent tool to detect the low-mass stellar population in optically absorbed regions. In this work, we present a study of the star-forming region Zeta-Ori and its surroundings. We combine optical, infrared and X-ray data. Properties of the X-ray emiting plasma and infrared features of the young stellar objects detected in the XMM-Newton observation are determined. The southern part of the Orion B giant molecular cloud complex harbor other star forming regions, as NGC 2023 and NGC 2024, we use this regions to compare. We study the spectral energy distribution of X-ray sources. Combining these results with infrared, the X-ray sources are classified as class I, class II and class III objects. The X-ray spectrum and ligth curve of detected X-ray sources is analyzed to found flares. We use a extincion-independent index to select the stars with circumstellar disk, and study the relationship between the present of disk and the flare energy. The results are similar to others studies and we conclude that the coronal properties of class II and class III objects in this region do not differ significantly from each other and from stars of similar infrared class in the ONC.
An introduction to the theory of local zeta functions
Igusa, Jun-ichi
2007-01-01
This book is an introductory presentation to the theory of local zeta functions. Viewed as distributions, and mostly in the archimedean case, local zeta functions are also called complex powers. The volume contains major results on analytic and algebraic properties of complex powers by Atiyah, Bernstein, I. M. Gelfand, S. I. Gelfand, and Sato. Chapters devoted to p-adic local zeta functions present Serre's structure theorem, a rationality theorem, and many examples found by the author. The presentation concludes with theorems by Denef and Meuser.
Dynamics and zeta functions on conformally compact manifolds
Rowlett, Julie; Tapie, Samuel
2011-01-01
In this note, we study the dynamics and associated zeta functions of conformally compact manifolds with variable negative sectional curvatures. We begin with a discussion of a larger class of manifolds known as convex co-compact manifolds with variable negative curvature. Applying results from dynamics on these spaces, we obtain optimal meromorphic extensions of weighted dynamical zeta functions and asymptotic counting estimates for the number of weighted closed geodesics. A meromorphic extension of the standard dynamical zeta function and the prime orbit theorem follow as corollaries. Finally, we investigate interactions between the dynamics and spectral theory of these spaces.
Cold collisions of SH- with He: Potential energy surface and rate coefficients
Bop, C. T.; Trabelsi, T.; Hammami, K.; Mogren Al Mogren, M.; Lique, F.; Hochlaf, M.
2017-09-01
Collisional energy transfer under cold conditions is of great importance from the fundamental and applicative point of view. Here, we investigate low temperature collisions of the SH- anion with He. We have generated a three-dimensional potential energy surface (PES) for the SH-(X1Σ+)-He(1S) van der Waals complex. The ab initio multi-dimensional interaction PES was computed using the explicitly correlated coupled cluster approach with simple, double, and perturbative triple excitation in conjunction with the augmented-correlation consistent-polarized valence triple zeta Gaussian basis set. The PES presents two minima located at linear geometries. Then, the PES was averaged over the ground vibrational wave function of the SH- molecule and the resulting two-dimensional PES was incorporated into exact quantum mechanical close coupling calculations to study the collisional excitation of SH- by He. We have computed inelastic cross sections among the 11 first rotational levels of SH- for energies up to 2500 cm-1. (De-)excitation rate coefficients were deduced for temperatures ranging from 1 to 300 K by thermally averaging the cross sections. We also performed calculations using the new PES for a fixed internuclear SH- distance. Both sets of results were found to be in reasonable agreement despite differences existing at low temperatures confirming that accurate predictions require the consideration of all internal degrees of freedom in the case of molecular hydrides. The rate coefficients presented here may be useful in interpreting future experimental work on the SH- negative ion colliding with He as those recently done for the OH--He collisional system as well as for possible astrophysical applications in case SH- would be detected in the interstellar medium.
Electrical mapping of microtubular structures by surface potential microscopy
Zhang, Peng; Cantiello, Horacio F.
2009-09-01
Microtubules (MTs) are important cytoskeletal polymers that play an essential role in cell division and transport in all eukaryotes and information processing in neurons. MTs are highly charged polyelectrolytes, composed of hollow cylindrical arrangements of αβ-tubulin dimers. To date, there is little information about electrical properties of MTs. Here, we deposited and dried MTs onto a gold-plated surface to image their topology by atomic force microscopy (AFM), and determined their electrical mapping with surface potential microscopy (SPM). We found a strong linear correlation between the magnitude of relative surface potential and MT parameters, including diameter and height. AFM images confirmed the cylindrical topology of microtubular structures, and the presence of topological discontinuities along their surface, which may contribute to their unique electrical properties.
Potential energy surfaces and reaction dynamics of polyatomic molecules
Energy Technology Data Exchange (ETDEWEB)
Chang, Yan-Tyng.
1991-11-01
A simple empirical valence bond (EVB) model approach is suggested for constructing global potential energy surfaces for reactions of polyatomic molecular systems. This approach produces smooth and continuous potential surfaces which can be directly utilized in a dynamical study. Two types of reactions are of special interest, the unimolecular dissociation and the unimolecular isomerization. For the first type, the molecular dissociation dynamics of formaldehyde on the ground electronic surface is investigated through classical trajectory calculations on EVB surfaces. The product state distributions and vector correlations obtained from this study suggest very similar behaviors seen in the experiments. The intramolecular hydrogen atom transfer in the formic acid dimer is an example of the isomerization reaction. High level ab initio quantum chemistry calculations are performed to obtain optimized equilibrium and transition state dimer geometries and also the harmonic frequencies.
Characterization of zeta (zeta): a new opioid receptor involved in growth.
Zagon, I S; Goodman, S R; McLaughlin, P J
1989-03-20
Endogenous opioid systems (i.e., opioids and opioid receptors) are known to play a role in neural cancer. Using [3H]-[Met5]enkephalin, a potent ligand involved in growth, specific and saturable binding was detected in homogenates of S20Y neuroblastoma transplanted into A/Jax mice; the data fit a single binding site. Scatchard analysis yielded a Kd of 0.49 nM and a binding capacity of 5.32 fmol/mg protein. Binding was dependent on protein concentration, time, temperature, and pH, and was sensitive to Na+ and guanine nucleotides. Optimal binding required protease inhibitors, and pretreatment of the tumor homogenates with trypsin markedly reduced [3H]-[Met5]enkephalin binding, suggesting that the binding site was proteinaceous in character. Displacement experiments indicated that [Met5]enkephalin was the most potent displacer of [3H]-[Met5]enkephalin; other ligands selective for mu, delta, kappa, epsilon, and sigma were not highly competitive. Given the functional significance of [Met5]enkephalin as a potent regulator of normal and abnormal growth, and that the receptor recognized by [Met5]enkephalin does not resemble any previously described, the present study has demonstrated the presence of a new opioid receptor termed zeta (zeta) (from the Greek 'Zoe', life) related to the proliferation of cells and tissues.
An adaptive interpolation scheme for molecular potential energy surfaces
Kowalewski, Markus; Larsson, Elisabeth; Heryudono, Alfa
2016-08-01
The calculation of potential energy surfaces for quantum dynamics can be a time consuming task—especially when a high level of theory for the electronic structure calculation is required. We propose an adaptive interpolation algorithm based on polyharmonic splines combined with a partition of unity approach. The adaptive node refinement allows to greatly reduce the number of sample points by employing a local error estimate. The algorithm and its scaling behavior are evaluated for a model function in 2, 3, and 4 dimensions. The developed algorithm allows for a more rapid and reliable interpolation of a potential energy surface within a given accuracy compared to the non-adaptive version.
An adaptive interpolation scheme for molecular potential energy surfaces
Kowalewski, Markus; Heryudono, Alfa
2016-01-01
The calculation of potential energy surfaces for quantum dynamics can be a time consuming task -- especially when a high level of theory for the electronic structure calculation is required. We propose an adaptive interpolation algorithm based on polyharmonic splines combined with a partition of unity approach. The adaptive node refinement allows to greatly reduce the number of sample points by employing a local error estimate. The algorithm and its scaling behavior is evaluated for a model function in 2, 3 and 4 dimensions. The developed algorithm allows for a more rapid and reliable interpolation of a potential energy surface within a given accuracy compared to the non-adaptive version.
Surface potential domains on lamellar P3OT structures
Energy Technology Data Exchange (ETDEWEB)
Perez-GarcIa, B [Departamento Fisica, Facultad de Quimica (Campus Espinardo), Universidad de Murcia, E-30100 Murcia (Spain); Abad, J [Departamento Fisica, Facultad de Quimica (Campus Espinardo), Universidad de Murcia, E-30100 Murcia (Spain); Urbina, A [Departamento Electronica, TecnologIa de Computadoras y Proyectos, Universidad Politecnica de Cartagena, E-30202 Cartagena (Spain); Colchero, J [Departamento Fisica, Facultad de Quimica (Campus Espinardo), Universidad de Murcia, E-30100 Murcia (Spain); Palacios-Lidon, E [Departamento Fisica, Facultad de Quimica (Campus Espinardo), Universidad de Murcia, E-30100 Murcia (Spain)
2008-02-13
In this work the electrostatic properties of poly(3-octylthiophene) thin films have been studied on a nanometer scale by means of electrostatic force microscopy and Kelvin probe microscopy (KPM). The KPM images reveal that different surface contact potential domains coexist on the polymer surface. This result, together with additional capacitance measurements, indicates that the potential domains are related to the existence of dipoles due to different molecular arrangements. Finally, capacitance measurements as a function of the tip-sample bias voltage show that in all regions large band bending effects take place.
Sliding surface searching method for slopes containing a potential weak structural surface
Directory of Open Access Journals (Sweden)
Aijun Yao
2014-06-01
Full Text Available Weak structural surface is one of the key factors controlling the stability of slopes. The stability of rock slopes is in general concerned with set of discontinuities. However, in soft rocks, failure can occur along surfaces approaching to a circular failure surface. To better understand the position of potential sliding surface, a new method called simplex-finite stochastic tracking method is proposed. This method basically divides sliding surface into two parts: one is described by smooth curve obtained by random searching, the other one is polyline formed by the weak structural surface. Single or multiple sliding surfaces can be considered, and consequently several types of combined sliding surfaces can be simulated. The paper will adopt the arc-polyline to simulate potential sliding surface and analyze the searching process of sliding surface. Accordingly, software for slope stability analysis using this method was developed and applied in real cases. The results show that, using simplex-finite stochastic tracking method, it is possible to locate the position of a potential sliding surface in the slope.
Sliding surface searching method for slopes containing a potential weak structural surface
Institute of Scientific and Technical Information of China (English)
Aijun Yao; Zhizhou Tian; Yongjun Jin
2014-01-01
Weak structural surface is one of the key factors controlling the stability of slopes. The stability of rock slopes is in general concerned with set of discontinuities. However, in soft rocks, failure can occur along surfaces approaching to a circular failure surface. To better understand the position of potential sliding surface, a new method called simplex-finite stochastic tracking method is proposed. This method basically divides sliding surface into two parts: one is described by smooth curve obtained by random searching, the other one is polyline formed by the weak structural surface. Single or multiple sliding surfaces can be considered, and consequently several types of combined sliding surfaces can be simu-lated. The paper will adopt the arc-polyline to simulate potential sliding surface and analyze the searching process of sliding surface. Accordingly, software for slope stability analysis using this method was developed and applied in real cases. The results show that, using simplex-finite stochastic tracking method, it is possible to locate the position of a potential sliding surface in the slope.
Lunar Surface Potential Increases during Terrestrial Bow Shock Traversals
Collier, Michael R.; Stubbs, Timothy J.; Hills, H. Kent; Halekas, Jasper; Farrell, William M.; Delory, Greg T.; Espley, Jared; Freeman, John W.; Vondrak, Richard R.; Kasper, Justin
2009-01-01
Since the Apollo era the electric potential of the Moon has been a subject of interest and debate. Deployed by three Apollo missions, Apollo 12, Apollo 14 and Apollo 15, the Suprathermal Ion Detector Experiment (SIDE) determined the sunlit lunar surface potential to be about +10 Volts using the energy spectra of lunar ionospheric thermal ions accelerated toward the Moon. We present an analysis of Apollo 14 SIDE "resonance" events that indicate the lunar surface potential increases when the Moon traverses the dawn bow shock. By analyzing Wind spacecraft crossings of the terrestrial bow shock at approximately this location and employing current balancing models of the lunar surface, we suggest causes for the increasing potential. Determining the origin of this phenomenon will improve our ability to predict the lunar surface potential in support of human exploration as well as provide models for the behavior of other airless bodies when they traverse similar features such as interplanetary shocks, both of which are goals of the NASA Lunar Science Institute's Dynamic Response of the Environment At the Moon (DREAM) team.
Reversible Compositional Control of Oxide Surfaces by Electrochemical Potentials
Mutoro, Eva
2012-01-05
Perovskite oxides can exhibit a wide range of interesting characteristics such as being catalytically active and electronically/ionically conducting, and thus, they have been used in a number of solid-state devices such as solid oxide fuel cells (SOFCs) and sensors. As the surface compositions of perovskites can greatly influence the catalytic properties, knowing and controlling their surface compositions is crucial to enhance device performance. In this study, we demonstrate that the surface strontium (Sr) and cobalt (Co) concentrations of perovskite-based thin films can be controlled reversibly at elevated temperatures by applying small electrical potential biases. The surface compositional changes of La 0.8Sr 0.2CoO 3-δ (LSC 113), (La 0.5Sr 0.5) 2CoO 4±δ (LSC 214), and LSC 214-decorated LSC 113 films (LSC 113/214) were investigated in situ by utilizing synchrotron-based X-ray photoelectron spectroscopy (XPS), where the largest changes of surface Sr were found for the LSC 113/214 surface. These findings offer the potential of reversibly controlling the surface functionality of perovskites. © 2011 American Chemical Society.
Potential Energy Surfaces of Nitrogen Dioxide for the Ground State
Institute of Scientific and Technical Information of China (English)
SHAO Ju-Xiang; ZHU Zheng-He; CHENG Xin-Lu; YANG Xiang-Dong
2007-01-01
The potential energy function of nitrogen dioxide with the C2v symmetry in the ground state is represented using the simplified Sorbie-Murrell many-body expansion function in terms of the symmetry of NO2. Using the potential energy function, some potential energy surfaces of NO2(C2v, X2A1), such as the bond stretching contour plot for a fixed equilibrium geometry angle θ and contour for O moving around N-O (R1), in which R1 is fixed at the equilibrium bond length, are depicted. The potential energy surfaces are analysed. Moreover, the equilibrium parameters for NO2 with the C2v, Cs and D8h symmetries, such as equilibrium geometry structures and energies, are calculated by the ab initio (CBS-Q) method.
Explicit bounds on the logarithmic derivative and the reciprocal of the Riemann zeta-function
Trudgian, Tim
2015-01-01
The purpose of this article is consider $|\\zeta'(\\sigma + it)/\\zeta(\\sigma + it)|$ and $|\\zeta(\\sigma + it)|^{-1}$ when $\\sigma$ is close to unity. We prove that $|\\zeta'(\\sigma + it)/\\zeta(\\sigma + it)| \\leq 87\\log t$ and $|\\zeta(\\sigma + it)|^{-1} \\leq 6.9\\times 10^{6} \\log t$ for $\\sigma \\geq 1-1/(8 \\log t)$ and $t\\geq 45$.
One-loop omega-potential of quantum fields with ellipsoid constant-energy surface dispersion law
Kazinski, P. O.; Shipulya, M. A.
2011-10-01
Rapidly convergent expansions of a one-loop contribution to the partition function of quantum fields with ellipsoid constant-energy surface dispersion law are derived. The omega-potential is naturally decomposed into three parts: the quasiclassical contribution, the contribution from the branch cut of the dispersion law, and the oscillating part. The low- and high-temperature expansions of the quasiclassical part are obtained. An explicit expression and a relation of the contribution from the cut with the Casimir term and vacuum energy are established. The oscillating part is represented in the form of the Chowla-Selberg expansion of the Epstein zeta function. Various resummations of this expansion are considered. The general procedure developed is then applied to two models: massless particles in a box both at zero and nonzero chemical potential, and electrons in a thin metal film. Rapidly convergent expansions of the partition function and average particle number are obtained for these models. In particular, the oscillations of the chemical potential of conduction electrons in graphene and a thin metal film due to a variation of size of the crystal are described.
Energy Technology Data Exchange (ETDEWEB)
Hellmann, Robert, E-mail: robert.hellmann@uni-rostock.de; Bich, Eckard; Vogel, Eckhard [Institut für Chemie, Universität Rostock, 18059 Rostock (Germany); Vesovic, Velisa [Department of Earth Science and Engineering, Imperial College London, London SW7 2AZ (United Kingdom)
2014-12-14
A five-dimensional potential energy surface (PES) for the interaction of a rigid methane molecule with a rigid nitrogen molecule was determined from quantum-chemical ab initio calculations. The counterpoise-corrected supermolecular approach at the CCSD(T) level of theory was utilized to compute a total of 743 points on the PES. The interaction energies were calculated using basis sets of up to quadruple-zeta quality with bond functions and were extrapolated to the complete basis set limit. An analytical site-site potential function with nine sites for methane and five sites for nitrogen was fitted to the interaction energies. The PES was validated by calculating the cross second virial coefficient as well as the shear viscosity and binary diffusion coefficient in the dilute-gas limit for CH{sub 4}–N{sub 2} mixtures. An improved PES was obtained by adjusting a single parameter of the analytical potential function in such a way that quantitative agreement with the most accurate experimental values of the cross second virial coefficient was achieved. The transport property values obtained with the adjusted PES are in good agreement with the best experimental data.
The Structural Evolution of Milky-Way-Like Star-Forming Galaxies zeta is approximately 1.3
Patel, Shannon G.; Fumagalli, Mattia; Franx, Marun; VanDokkum, Pieter G.; VanDerWel, Arjen; Leja, Joel; Labbe, Ivo; Brammr, Gabriel; Whitaker, Katherine E.; Skelton, Rosalind E.; Momcheva, Ivelina; Lundgren, Britt; Muzzin, Adam; Quadri, Ryan F.; Nelson, Erica June; Wake, David A.; Rix, Hans-Walter
2013-01-01
We follow the structural evolution of star-forming galaxies (SFGs) like the Milky Way by selecting progenitors to zeta is approx. 1.3 based on the stellar mass growth inferred from the evolution of the star-forming sequence. We select our sample from the 3D-HT survey, which utilizes spectroscopy from the HST-WFC3 G141 near-IR grism and enables precise redshift measurements for our sample of SFGs. Structural properties are obtained from Sersic profile fits to CANDELS WFC3 imaging. The progenitors of zeta = 0 SFGs with stellar mass M = 10(exp 10.5) solar mass are typically half as massive at zeta is approx. 1. This late-time stellar mass grow is consistent with recent studies that employ abundance matching techniques. The descendant SFGs at zeta is approx. 0 have grown in half-light radius by a factor of approx. 1.4 zeta is approx. 1. The half-light radius grows with stellar mass as r(sub e) alpha stellar mass(exp 0.29). While most of the stellar mass is clearly assembling at large radii, the mass surface density profiles reveal ongoing mass growth also in the central regions where bulges and pseudobulges are common features in present day late-type galaxies. Some portion of this growth in the central regions is due to star formation as recent observations of H(a) maps for SFGs at zeta approx. are found to be extended but centrally peaked. Connecting our lookback study with galactic archeology, we find the stellar mass surface density at R - 8 kkpc to have increased by a factor of approx. 2 since zeta is approx. 1, in good agreement with measurements derived for the solar neighborhood of the Milky Way.
Seiberg Duality, Quiver Gauge Theories, and Ihara Zeta Function
Zhou, Da; He, Yang-Hui
2015-01-01
We study Ihara zeta function for graphs in the context of quivers arising from gauge theories, especially under Seiberg duality transformations. The distribution of poles is studied as we proceed along the duality tree, in light of the weak and strong graph versions of the Riemann Hypothesis. As a by-product, we find a refined version of Ihara zeta function to be the generating function for the generic superpotential of the gauge theory.
On the Zeta Function of a Family of Quintics
Goutet, Philippe
2009-01-01
In this article, we give a proof of the link between the zeta function of two families of hypergeometric curves and the zeta function of a family of quintics that was observed numerically by Candelas, de la Ossa, and Rodriguez Villegas. The method we use is based on formulas of Koblitz and various Gauss sums identities; it does not give any geometric information on the link.
Gidofalvi, Gergely; Mazziotti, David A
2005-05-15
The acceleration of the variational two-electron reduced-density-matrix (2-RDM) method, using a new first-order algorithm [D. A. Mazziotti, Phys. Rev. Lett. 93, 213001 (2004)], has shown its usefulness in the accurate description of potential energy surfaces in nontrivial basis sets. Here we apply the first-order 2-RDM method to the potential energy surfaces of the nitrogen and carbon dimers in polarized valence double-zeta basis sets for which benchmark full-configuration-interaction calculations exist. In a wave function formalism accurately stretching the triple bond of the nitrogen dimer requires at least six-particle excitations from the Hartree-Fock reference. Furthermore, cleaving the double bond of C2 should produce a "non-Morse"-like potential curve because the ground state near equilibrium (X 1sigma(g)+) has an avoided crossing with the second excited state (B' 1sigma(g)+) and a level crossing with the first excited state (B 1delta(g)). Because the 2-RDM method variationally optimizes the energy over correlated 2-RDMs on the two-electron space without parametrization of the many-electron wave function, it captures multireference correlations that are difficult to describe with approximate wave functions. The 2-RDM method yields for N2 a potential energy surface with features and spectroscopic constants that are more accurate than those from single-reference methods and similar in accuracy to multireference techniques, and it describes the non-Morse-like behavior of C2 which is not captured by single-reference methods.
Conservation of $\\zeta$ with radiative corrections from heavy field
Tanaka, Takahiro
2015-01-01
In this paper, we address a possible impact of radiative corrections from a heavy scalar field $\\chi$ on the curvature perturbation $\\zeta$. Integrating out $\\chi$, we derive the effective action for $\\zeta$, which includes the loop corrections of the heavy field $\\chi$. When the mass of $\\chi$ is much larger than the Hubble scale $H$, the loop corrections of $\\chi$ only yield a local contribution in the effective action and hence the effective action simply gives an action for $\\zeta$ in a single field model, where, as is widely known, $\\zeta$ is conserved in time after the Hubble crossing time. Meanwhile, when the mass of $\\chi$ is comparable to $H$, the loop corrections of $\\chi$ can give a non-local contribution to the effective action. Because of the non-local contribution from $\\chi$, in general, $\\zeta$ may not be conserved, even if the classical background trajectory is determined only by the evolution of the inflaton. In this paper, we derive the condition that $\\zeta$ is conserved in time in the pre...
He-, Ne-, and Ar-phosgene intermolecular potential energy surfaces
DEFF Research Database (Denmark)
Munteanu, Cristian R.; Henriksen, Christian; Felker, Peter M.
2013-01-01
Using the CCSD(T) model, we evaluated the intermolecular potential energy surfaces of the He-, Ne-, and Ar-phosgene complexes. We considered a representative number of intermolecular geometries for which we calculated the corresponding interaction energies with the augmented (He complex) and double...
Communication: Fitting potential energy surfaces with fundamental invariant neural network
Shao, Kejie; Chen, Jun; Zhao, Zhiqiang; Zhang, Dong H.
2016-08-01
A more flexible neural network (NN) method using the fundamental invariants (FIs) as the input vector is proposed in the construction of potential energy surfaces for molecular systems involving identical atoms. Mathematically, FIs finitely generate the permutation invariant polynomial (PIP) ring. In combination with NN, fundamental invariant neural network (FI-NN) can approximate any function to arbitrary accuracy. Because FI-NN minimizes the size of input permutation invariant polynomials, it can efficiently reduce the evaluation time of potential energy, in particular for polyatomic systems. In this work, we provide the FIs for all possible molecular systems up to five atoms. Potential energy surfaces for OH3 and CH4 were constructed with FI-NN, with the accuracy confirmed by full-dimensional quantum dynamic scattering and bound state calculations.
Can atom-surface potential measurements test atomic structure models?
Lonij, Vincent P A; Klauss, Catherine E; Holmgren, William F; Cronin, Alexander D
2011-06-30
van der Waals (vdW) atom-surface potentials can be excellent benchmarks for atomic structure calculations. This is especially true if measurements are made with two different types of atoms interacting with the same surface sample. Here we show theoretically how ratios of vdW potential strengths (e.g., C₃(K)/C₃(Na)) depend sensitively on the properties of each atom, yet these ratios are relatively insensitive to properties of the surface. We discuss how C₃ ratios depend on atomic core electrons by using a two-oscillator model to represent the contribution from atomic valence electrons and core electrons separately. We explain why certain pairs of atoms are preferable to study for future experimental tests of atomic structure calculations. A well chosen pair of atoms (e.g., K and Na) will have a C₃ ratio that is insensitive to the permittivity of the surface, whereas a poorly chosen pair (e.g., K and He) will have a ratio of C₃ values that depends more strongly on the permittivity of the surface.
Environmental surface cleanliness and the potential for contamination during handwashing.
Griffith, Christopher J; Malik, Rifhat; Cooper, Rose A; Looker, Nick; Michaels, Barry
2003-04-01
Effective handwashing (including drying) is important in infection control. The ability of the various stages of handwashing to decrease skin-surface microbial counts has been documented. However, an important element, environmental surface cleanliness, and the potential for contamination of hands during the process has not been well studied or quantified. An examination of the adenosine triphosphate (a measure of residual organic soil), bacterial, and staphylococcal load on ward handwash station surfaces, which could be touched during handwashing, is reported. Hand contact surfaces tested consisted of approximately 620 each of: faucet handles, soap dispenser activator mechanisms, and folded paper-towel dispenser exits. Failure rates in excess of benchmark clean values were higher with adenosine triphosphate assays than microbial counts. This could indicate the presence of a higher level of general organic debris (eg, skin cells) as opposed to microbial contamination or could reflect greater assay sensitivity. Faucet handles were more likely to be contaminated and be in excess of benchmark values than paper-towel dispenser exits. However, the latter are likely to be the final surface touched during the handwashing process and overall nearly 20% were above microbiologic benchmark values. Many of the organisms isolated were staphylococci and the results are discussed within the context of microbial cross-contamination and potential pathogen spread.
Directory of Open Access Journals (Sweden)
Hadis Rahmani Incheh Keykanlu
2016-12-01
Full Text Available Acording to the prevalence of cancer in today's societies, it is too important to find new drugs for that treatment. Cationic antimicrobial peptides that are able to eliminate a wide range of bacteria, fungi, parasites, viruses and unicellular, are natural anti-cancer agents. In the present study, the effect of cationic peptides of bee venom Melittin (ML and Lactoferrin (LF of camel milk which was loaded on the Perfluorooctyl Bromide (PFOB nanoparticles, were examined on MCF7 cells. Nanoparticles using oil in water emulsion was prepared by ultra-thoracic and ultrasonic. Then ML and LF were separately added to the nanoparticles then incorporation of them were confirmed by tryptophan fluorescence and circular dichroism (CD spectra. The mean diameter of the nanoparticles did not change after addition of ML and LF (~100 nm, but as expected, the zeta potential of the nanoparticles with increasing of ML and LF concentrations to the preformed nanoparticles increased from -18.43(without ML and LF to +21.61(LF 110.66µg/ml and +20.93(ML 0.1µg/ml and +23.75(LF 110.66µg/ml and ML 0.1µg/ml. By using of scanning electron microscopy (SEM, the morphology and structure of nanoparticles was investigated, homogeneity and uniformity during processing and loading of ML and LF was observed. Effectiveness of nanoparticles loaded on cancer cells was performed with MTT test. The results showed that ML and LF had a positive effect on cancer cell death. Percent of cell death was higher when ML and LF was loaded on nanoparticles. With increase of ML and LF concentration loading on nanoparticles, increases cancer cell death. Minitab software was used to analyze some data.
Calculating vibrational spectra using modified Shepard interpolated potential energy surfaces.
Evenhuis, Christian R; Manthe, Uwe
2008-07-14
A potential energy interpolation approach based on modified Shepard interpolation and specifically designed for calculation of vibrational states is presented. The importance of the choice of coordinates for the rate of convergence is demonstrated. Studying the vibrational states of the water molecule as a test case, a coordinate system comprised of inverse bond distances and trigonometric functions of the bond angle is found to be particularly efficient. Different sampling schemes used to locate the reference points in the modified Shepard interpolation are investigated. A final scheme is recommended, which allows the construction of potential energy surfaces to sub-wave-number accuracy.
Quantum mechanics of effective potential at a metal surface
Solomatin, Alexander
In this thesis we study the nonuniform electron density system at a metal-vacuum interface via the corresponding local effective potential confining the electrons, the metal being represented by the jellium and structureless pseudopotential models. The study is performed within conventional Kohn-Sham (KS) density-functional theory and its recently derived quantum-mechanical interpretation. In the latter, properties are determined in terms of the separate electron correlations due to the Pauli exclusion principle, Coulomb repulsion and the correlation contribution to the kinetc energy. We have derived the exact analytical structure, valid for self-consistent orbitals, of the KS theory exchange potential in the classically forbidden region. This structure is image-potential-like of the form -alphasb{KS,x}(beta)chi where the parameter betasp2 is the ratio of the surface barrier height to the metal Fermi energy. For a Wigner-Seitz radius of rsb{s} = 4.1, which is approximately that for which jellium metal is stable, the decay coefficient is precisely 1/4. Over the metallic range of densities rsb{s} = 2-6, the coefficient ranges from 0.195 to 0.274. Thus, if the asymptotic structure of the KS exchange-correlation potential is the image potential, then this structure is due principally to KS exchange effects, the KS correlation contribution being an order of magnitude smaller. These results, then lead to the concept of an 'image' charge localized to the surface region for asymptotic positions of the electron. We have further derived the exact analytical structure in the vacuum of the Slater exchange potential, and of the Pauli-correlation and correlation-kinetic components of the KS exchange potential. These structures are all image-potential-like, decaying respectively as -alphasb{S}(beta)chi,\\ -alphasb{W}(beta)chi and alphasbsp{tsb{c}}{(1)}(beta)/chi. The Pauli-correlation component constitutes the major fraction of the KS exchange potential asymptotically, but there
Three-dimensional potential energy surface of Ar–CO
Energy Technology Data Exchange (ETDEWEB)
Sumiyoshi, Yoshihiro, E-mail: y-sumiyoshi@gunma-u.ac.jp [Division of Pure and Applied Science, Graduate School of Science and Technology, Gunma University, 4-2 Aramaki, Maebashi, Gunma 371-8510 (Japan); Endo, Yasuki [Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8902 (Japan)
2015-01-14
A three-dimensional intermolecular potential energy surface of the Ar–CO complex has been determined by fitting most of the previously reported spectroscopic data, where observed transition frequencies by microwave, millimeter-wave, submillimeter-wave, and infrared spectroscopy were reproduced simultaneously within their experimental accuracies. A free rotor model Hamiltonian considering all the freedom of motions for an atom-diatom system was applied to calculate vibration-rotation energies. A three-dimensional potential energy surface obtained by ab initio calculations at the CCSD(T)-F12b/aug-cc-pV5Z level of theory was parameterized by a model function consisting of 46 parameters. They were used as initial values for the least-squares analysis of the experimental data. A total of 20 parameters were optimized to reproduce all the spectroscopic data.
Electronic structure, molecular bonding and potential energy surfaces
Energy Technology Data Exchange (ETDEWEB)
Ruedenberg, K. [Ames Laboratory, IA (United States)
1993-12-01
By virtue of the universal validity of the generalized Born-Oppenheimer separation, potential energy surfaces (PES`) represent the central conceptual as well as quantitative entities of chemical physics and provide the basis for the understanding of most physicochemical phenomena in many diverse fields. The research in this group deals with the elucidation of general properties of PES` as well as with the quantitative determination of PES` for concrete systems, in particular pertaining to reactions involving carbon, oxygen, nitrogen and hydrogen molecules.
Theoretical studies of potential energy surfaces and computational methods
Energy Technology Data Exchange (ETDEWEB)
Shepard, R. [Argonne National Laboratory, IL (United States)
1993-12-01
This project involves the development, implementation, and application of theoretical methods for the calculation and characterization of potential energy surfaces involving molecular species that occur in hydrocarbon combustion. These potential energy surfaces require an accurate and balanced treatment of reactants, intermediates, and products. This difficult challenge is met with general multiconfiguration self-consistent-field (MCSCF) and multireference single- and double-excitation configuration interaction (MRSDCI) methods. In contrast to the more common single-reference electronic structure methods, this approach is capable of describing accurately molecular systems that are highly distorted away from their equilibrium geometries, including reactant, fragment, and transition-state geometries, and of describing regions of the potential surface that are associated with electronic wave functions of widely varying nature. The MCSCF reference wave functions are designed to be sufficiently flexible to describe qualitatively the changes in the electronic structure over the broad range of geometries of interest. The necessary mixing of ionic, covalent, and Rydberg contributions, along with the appropriate treatment of the different electron-spin components (e.g. closed shell, high-spin open-shell, low-spin open shell, radical, diradical, etc.) of the wave functions, are treated correctly at this level. Further treatment of electron correlation effects is included using large scale multireference CI wave functions, particularly including the single and double excitations relative to the MCSCF reference space. This leads to the most flexible and accurate large-scale MRSDCI wave functions that have been used to date in global PES studies.
Effect of oxygen plasma treatment on surface charge and wettability of PVC blood bag—In vitro assay
Khorasani, M. T.; Mirzadeh, H.
2007-06-01
Wettability and zeta potential studies were performed to characterize the hydrophobicity and surface charge of PVC blood bag samples and evaluate the effect of these properties on fibroblast cells growth. The surface properties of PVC and plasma treated PVC were compared by water drop contact angle and zeta potential measurement. Light microscopy was used to study the behavior of cell attachment and growth on these surfaces. Water drop contact angle measurement shows that the plasma treated PVC becomes more hydrophilic and wettability increased. Zeta potential and in vitro cell culture measurements noticed that the plasma treated PVC surface is more negatively charge and consequently attachment of the L929 fibroblast cells decreased on this surface.
Effect of oxygen plasma treatment on surface charge and wettability of PVC blood bag-In vitro assay
Energy Technology Data Exchange (ETDEWEB)
Khorasani, M.T. [Biomaterial Department of Iran Polymer and Petrochemical Institute, P.O. Box: 14965/115, Tehran (Iran, Islamic Republic of)]. E-mail: M.Khorasani@ippi.ac.ir; Mirzadeh, H. [Biomaterial Department of Iran Polymer and Petrochemical Institute, P.O. Box: 14965/115, Tehran (Iran, Islamic Republic of)
2007-06-15
Wettability and zeta potential studies were performed to characterize the hydrophobicity and surface charge of PVC blood bag samples and evaluate the effect of these properties on fibroblast cells growth. The surface properties of PVC and plasma treated PVC were compared by water drop contact angle and zeta potential measurement. Light microscopy was used to study the behavior of cell attachment and growth on these surfaces. Water drop contact angle measurement shows that the plasma treated PVC becomes more hydrophilic and wettability increased. Zeta potential and in vitro cell culture measurements noticed that the plasma treated PVC surface is more negatively charge and consequently attachment of the L929 fibroblast cells decreased on this surface.
Novel mixture model for the representation of potential energy surfaces
Pham, Tien Lam; Kino, Hiori; Terakura, Kiyoyuki; Miyake, Takashi; Dam, Hieu Chi
2016-10-01
We demonstrate that knowledge of chemical physics on a materials system can be automatically extracted from first-principles calculations using a data mining technique; this information can then be utilized to construct a simple empirical atomic potential model. By using unsupervised learning of the generative Gaussian mixture model, physically meaningful patterns of atomic local chemical environments can be detected automatically. Based on the obtained information regarding these atomic patterns, we propose a chemical-structure-dependent linear mixture model for estimating the atomic potential energy. Our experiments show that the proposed mixture model significantly improves the accuracy of the prediction of the potential energy surface for complex systems that possess a large diversity in their local structures.
A proof of the Riemann hypothesis by using the series representation of the Riemann zeta function
Tan, Shanguang
2011-01-01
The Riemann hypothesis was proved in this paper. First, a curve integral of the Riemann zeta function zeta(s) was formed, which is along a horizontal line from s to 1-\\bar{s} which are two nontrivial zeros of zeta(s) and symmetric about the vertical line Re s=1/2. Next, the result of the curve integral was derived and proved equal to zero. Then, by proving a lemma of central dissymmetry of the Riemann zeta function zeta(s), two nontrivial zeros s and 1-\\bar{s} were proved being a same zero or satisfying 1-\\bar{s}=s. Hence, the nontrivial zeros of zeta(s) all have real part Re s=1/2, that is, the Riemann hypothesis was proved.
Generalised root identities for zeta functions of curves over finite fields
Stone, Richard
2012-01-01
We consider generalised root identities for zeta functions of curves over finite fields, \\zeta_{k}, and compare with the corresponding analysis for the Riemann zeta function. We verify numerically that, as for \\zeta, the \\zeta_{k} do satisfy the generalised root identities and we investigate these in detail for the special cases of \\mu=0,-1\\:\\&\\:-2. Unlike for \\zeta, however, we show that in the setting of zeta functions of curves over finite fields the \\mu=-2 root identity is consistent with the Riemann hypothesis (RH) proved by Weil. Comparison of this analysis with the corresponding calculations for \\zeta illuminates the fact that, even though both \\zeta and \\zeta_{k} have both Euler and Hadamard product representations, it is the detailed structure of the counting function, N(T), which drives the Cesaro computations on the root side of these identities and thereby determines the implications of the root identities for RH in each setting.
On the breakdown of the curvature perturbation $\\zeta$ during reheating
Algan, Merve Tarman; Kutluk, Emine Seyma
2015-01-01
It is known that in single scalar field inflationary models the standard curvature perturbation \\zeta, which is supposedly conserved at superhorizon scales, diverges during reheating at times d\\Phi/dt=0, i.e. when the time derivative of the background inflaton field vanishes. This happens because the comoving gauge \\phi=0, where \\phi\\ denotes the inflaton perturbation, breaks down when d\\Phi/dt=0. The issue is usually bypassed by averaging out the inflaton oscillations but strictly speaking the evolution of \\zeta\\ is ill posed mathematically. We solve this problem by introducing a family of smooth gauges that still eliminates the inflaton fluctuation \\phi\\ in the Hamiltonian formalism and gives a well behaved curvature perturbation \\zeta, which is now rigorously conserved at superhorizon scales. In the linearized theory, this conserved variable can be used to unambiguously propagate the inflationary perturbations from the end of inflation to subsequent epochs. We discuss the implications of our results for th...
Analytic continuation of the Hurwitz Zeta Function with physical application
Barone-Adesi, V; Adesi, Vittorio Barone; Zerbini, Sergio
2001-01-01
A new formula relating the analytic continuation ofthe Hurwitz zeta function to the Euler gamma function and a "Schwinger" type series is presented. In particular, the value of the derivative of the real part of the analytic continuation of the Hurwitz zeta function for even negative integers and the imaginary one for odd negative integers are explicitly given. The result can be of interest both on mathematical and physical side, because we are able to apply our new formulas in the context of the Spectral Zeta Function regularization of one-loop Quantum Field Theory, computing the exact pair production rate per space-time unit of massive Dirac particles interacting with a purely electric background field.
DEFF Research Database (Denmark)
Regina, Viduthalai R.; Lokanathan, Arcot R.; Modrzynski, Jakub Jan;
2014-01-01
DNA-mediated adhesion depends on the physicochemical properties of the surface and surrounding liquid. We investigated eDNA alteration of cell surface hydrophobicity and zeta potential, and subsequently quantified the effect of eDNA on the adhesion of Staphylococcus xylosus to glass surfaces functionalised...... ionic strengths. No effect was seen on glass surfaces and carboxyl-functionalised surfaces at high ionic strength, and a reverse effect occurred on amine-functionalised surfaces at low ionic strength. However, eDNA promoted adhesion of cells to hydrophobic surfaces irrespective of the ionic strength...... with different chemistries resulting in variable hydrophobicity and charge. Cell adhesion experiments were carried out at three different ionic strengths. Removal of eDNA from S. xylosus cells by DNase treatment did not alter the zeta potential, but rendered the cells more hydrophilic. DNase treatment impaired...
Effective medium potentials for molecule-surface interactions: H2 on Cu and Ni surfaces
DEFF Research Database (Denmark)
Nørskov, Jens Kehlet
1989-01-01
that the functional form of the total energy expression is derived from density functional theory, that each of the terms entering can be given a precise physical interpretation, and that most of the parameters entering can be calculated, within the local density approximation. The method is explicitly derived for H2...... outside metal surfaces and the applicability is illustrated for H2 adsorbing on various Cu and Ni surfaces. Although very approximate, the calculated potentials seem to include a number of features observed experimentally: Ni is more active in dissociating H2 than Cu, and open surfaces are more active...
A new generalization of the Riemann zeta function and its difference equation
Directory of Open Access Journals (Sweden)
Qadir Asghar
2011-01-01
Full Text Available Abstract We have introduced a new generalization of the Riemann zeta function. A special case of our generalization converges locally uniformly to the Riemann zeta function in the critical strip. It approximates the trivial and non-trivial zeros of the Riemann zeta function. Some properties of the generalized Riemann zeta function are investigated. The relation between the function and the general Hurwitz zeta function is exploited to deduce new identities.
Potential energy surface of the CO{sub 2}–N{sub 2} van der Waals complex
Energy Technology Data Exchange (ETDEWEB)
Nasri, Sameh; Ajili, Yosra [Laboratoire de Spectroscopie Atomique, Moléculaire et Applications-LSAMA, Université de Tunis El Manar, Tunis (Tunisia); Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 5 bd Descartes, 77454 Marne-la-Vallée (France); Jaidane, Nejm-Eddine [Laboratoire de Spectroscopie Atomique, Moléculaire et Applications-LSAMA, Université de Tunis El Manar, Tunis (Tunisia); Kalugina, Yulia N. [Department of Optics and Spectroscopy, Tomsk State University, 36 Lenin Ave., Tomsk 634050 (Russian Federation); Halvick, Philippe; Stoecklin, Thierry [Institut des Sciences Moléculaires, Université de Bordeaux, CNRS UMR 5255, 33405 Talence Cedex (France); Hochlaf, Majdi, E-mail: hochlaf@univ-mlv.fr [Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 5 bd Descartes, 77454 Marne-la-Vallée (France)
2015-05-07
Four-dimensional potential energy surface (4D-PES) of the atmospherically relevant CO{sub 2}–N{sub 2} van der Waals complex is generated using the explicitly correlated coupled cluster with single, double, and perturbative triple excitation (CCSD(T)-F12) method in conjunction with the augmented correlation consistent triple zeta (aug-cc-pVTZ) basis set. This 4D-PES is mapped along the intermonomer coordinates. An analytic fit of this 4D-PES is performed. Our extensive computations confirm that the most stable form corresponds to a T-shape structure where the nitrogen molecule points towards the carbon atom of CO{sub 2}. In addition, we located a second isomer and two transition states in the ground state PES of CO{sub 2}–N{sub 2}. All of them lay below the CO{sub 2} + N{sub 2} dissociation limit. This 4D-PES is flat and strongly anisotropic along the intermonomer coordinates. This results in the possibility of the occurrence of large amplitude motions within the complex, such as the inversion of N{sub 2}, as suggested in the recent spectroscopic experiments. Finally, we show that the experimentally established deviations from the C{sub 2v} structure at equilibrium for the most stable isomer are due to the zero-point out-of-plane vibration correction.
Mayer Transfer Operator Approach to Selberg Zeta Function
DEFF Research Database (Denmark)
Momeni, Arash; Venkov, Alexei
These notes are based on three lectures given by the second author at Copenhagen University (October 2009) and at Aarhus University, Denmark (December 2009). We mostly present here a survey of results of Dieter Mayer on relations between Selberg and Smale-Ruelle dynamical zeta functions. In a spe...... in terms of a Fredholm determinant of a classical transfer operator of the flow. The transfer operator is defined in a certain space of holomorphic functions and its matrix representation in a natural basis is given in terms of the Riemann zeta function and the Euler gamma function....
From Fourier Series to Rapidly Convergent Series for Zeta(3)
DEFF Research Database (Denmark)
Scheufens, Ernst E
2011-01-01
The article presents a mathematical study which investigates the exact values of the Riemann zeta (ζ) function. It states that exact values can be determined from Fourier series for periodic versions of even power functions. It notes that using power series for logarithmic functions on this such ......The article presents a mathematical study which investigates the exact values of the Riemann zeta (ζ) function. It states that exact values can be determined from Fourier series for periodic versions of even power functions. It notes that using power series for logarithmic functions...
Measuring surface flow velocity with smartphones: potential for citizen observatories
Weijs, Steven V.; Chen, Zichong; Brauchli, Tristan; Huwald, Hendrik
2014-05-01
Stream flow velocity is an important variable for discharge estimation and research on sediment dynamics. Given the influence of the latter on rating curves (stage-discharge relations), and the relative scarcity of direct streamflow measurements, surface velocity measurements can offer important information for, e.g., flood warning, hydropower, and hydrological science and engineering in general. With the growing amount of sensing and computing power in the hands of more outdoorsy individuals, and the advances in image processing techniques, there is now a tremendous potential to obtain hydrologically relevant data from motivated citizens. This is the main focus of the interdisciplinary "WeSenseIt" project, a citizen observatory of water. In this subproject, we investigate the feasibility of stream flow surface velocity measurements from movie clips taken by (smartphone-) cameras. First results from movie-clip derived velocity information will be shown and compared to reference measurements.
On the Potential Predictability of Seasonal Land-Surface Climate
Energy Technology Data Exchange (ETDEWEB)
Phillips, T J
2001-10-01
The chaotic behavior of the continental climate of an atmospheric general circulation model is investigated from an ensemble of decadal simulations with common specifications of radiative forcings and monthly ocean boundary conditions, but different initial states of atmosphere and land. The variability structures of key model land-surface processes appear to agree sufficiently with observational estimates to warrant detailed examination of their predictability on seasonal time scales. This predictability is inferred from several novel measures of spatio-temporal reproducibility applied to eleven model variables. The reproducibility statistics are computed for variables in which the seasonal cycle is included or excluded, the former case being most pertinent to climate model simulations, and the latter to predictions of the seasonal anomalies. Because the reproducibility metrics in the latter case are determined in the context of a ''perfectly'' known ocean state, they are properly viewed as estimates of the potential predictability of seasonal climate. Inferences based on these reproducibility metrics are shown to be in general agreement with those derived from more conventional measures of potential predictability. It is found that the land-surface variables which include the seasonal cycle are impacted only marginally by changes in initial conditions; moreover, their seasonal climatologies exhibit high spatial reproducibility. In contrast, the reproducibility of a seasonal land-surface anomaly is generally low, although it is considerably higher in the Tropics; its spatial reproducibility also fluctuates in tandem with warm and cold phases of the El Nino/Southern Oscillation phenomenon. However, the detailed sensitivities to initial conditions depend somewhat on the land-surface process: pressure and temperature anomalies exhibit the highest temporal reproducibilities, while hydrological and turbulent flux anomalies show the highest spatial
77 FR 72975 - Zeta Cypermethrin; Pesticide Tolerances
2012-12-07
... = 11.20 mg/ old and adults). mg/kg. day. kg based on motor UFA = 10x aPAD = 0.07 mg/kg/day.. activity... the rat. LOAEL = HED = 1.15 mg/kg/day... 0.05 mg/L based on UFA = 3x increased salivation. UFH = 10x... = uncertainty factor. UFA = extrapolation from animal to human (interspecies). UFH = potential variation...
Pseudospectral Gaussian quantum dynamics: Efficient sampling of potential energy surfaces
Heaps, Charles W.; Mazziotti, David A.
2016-04-01
Trajectory-based Gaussian basis sets have been tremendously successful in describing high-dimensional quantum molecular dynamics. In this paper, we introduce a pseudospectral Gaussian-based method that achieves accurate quantum dynamics using efficient, real-space sampling of the time-dependent basis set. As in other Gaussian basis methods, we begin with a basis set expansion using time-dependent Gaussian basis functions guided by classical mechanics. Unlike other Gaussian methods but characteristic of the pseudospectral and collocation methods, the basis set is tested with N Dirac delta functions, where N is the number of basis functions, rather than using the basis function as test functions. As a result, the integration for matrix elements is reduced to function evaluation. Pseudospectral Gaussian dynamics only requires O ( N ) potential energy calculations, in contrast to O ( N 2 ) evaluations in a variational calculation. The classical trajectories allow small basis sets to sample high-dimensional potentials. Applications are made to diatomic oscillations in a Morse potential and a generalized version of the Henon-Heiles potential in two, four, and six dimensions. Comparisons are drawn to full analytical evaluation of potential energy integrals (variational) and the bra-ket averaged Taylor (BAT) expansion, an O ( N ) approximation used in Gaussian-based dynamics. In all cases, the pseudospectral Gaussian method is competitive with full variational calculations that require a global, analytical, and integrable potential energy surface. Additionally, the BAT breaks down when quantum mechanical coherence is particularly strong (i.e., barrier reflection in the Morse oscillator). The ability to obtain variational accuracy using only the potential energy at discrete points makes the pseudospectral Gaussian method a promising avenue for on-the-fly dynamics, where electronic structure calculations become computationally significant.
Potential Energy Surfaces Using Algebraic Methods Based on Unitary Groups
Directory of Open Access Journals (Sweden)
Renato Lemus
2011-01-01
Full Text Available This contribution reviews the recent advances to estimate the potential energy surfaces through algebraic methods based on the unitary groups used to describe the molecular vibrational degrees of freedom. The basic idea is to introduce the unitary group approach in the context of the traditional approach, where the Hamiltonian is expanded in terms of coordinates and momenta. In the presentation of this paper, several representative molecular systems that permit to illustrate both the different algebraic approaches as well as the usual problems encountered in the vibrational description in terms of internal coordinates are presented. Methods based on coherent states are also discussed.
Potential Energy Surfaces and Quantum Yields for Photochromic Diarylethene Reactions
Directory of Open Access Journals (Sweden)
Makoto Hatakeyama
2013-05-01
Full Text Available Photochromic diarylethenes (DAEs are among the most promising molecular switching systems for future molecular electronics. Numerous derivatives have been synthesized recently, and experimental quantum yields (QYs have been reported for two categories of them. Although the QY is one of the most important properties in various applications, it is also the most difficult property to predict before a molecule is actually synthesized. We have previously reported preliminary theoretical studies on what determines the QYs in both categories of DAE derivatives. Here, reflecting theoretical analyses of potential energy surfaces and recent experimental results, a rational explanation of the general guiding principle for QY design is presented for future molecular design.
Taboo search by successive confinement: Surveying a potential energy surface
Chekmarev, Sergei F.
2001-09-01
A taboo search for minima on a potential energy surface (PES) is performed by means of confinement molecular dynamics: the molecular dynamics trajectory of the system is successively confined to various basins on the PES that have not been sampled yet. The approach is illustrated for a 13-atom Lennard-Jones cluster. It is shown that the taboo search radically accelerates the process of surveying the PES, with the probability of finding a new minimum defined by a propagating Fermi-like distribution.
Accurate global potential energy surface for the H + OH+ collision
Gannouni, M. A.; Jaidane, N. E.; Halvick, P.; Stoecklin, T.; Hochlaf, M.
2014-05-01
We mapped the global three-dimensional potential energy surface (3D-PES) of the water cation at the MRCI/aug-cc-pV5Z including the basis set superposition (BSSE) correction. This PES covers the molecular region and the long ranges close to the H + OH+(X3Σ-), the O + H2+(X2Σg+), and the hydrogen exchange channels. The quality of the PES is checked after comparison to previous experimental and theoretical results of the spectroscopic constants of H2O+(tilde X2B1) and of the diatomic fragments, the vibronic spectrum, the dissociation energy, and the barrier to linearity for H2O+(tilde X2B1). Our data nicely approach those measured and computed previously. The long range parts reproduce quite well the diatomic potentials. In whole, a good agreement is found, which validates our 3D-PES.
Simple realization of inflaton potential on a Riemann surface
Directory of Open Access Journals (Sweden)
Keisuke Harigaya
2014-11-01
Full Text Available The observation of the B-mode in the cosmic microwave background radiation combined with the so-called Lyth bound suggests the trans-Planckian variation of the inflaton field during inflation. Such a large variation generates concerns over inflation models in terms of the effective field theory below the Planck scale. If the inflaton resides in a Riemann surface and the inflaton potential is a multivalued function of the inflaton field when it is viewed as a function on a complex plane, the Lyth bound can be satisfied while keeping field values in the effective field theory within the Planck scale. We show that a multivalued inflaton potential can be realized starting from a single-valued Lagrangian of the effective field theory below the Planck scale.
Jiang, Bin; Guo, Hua
2014-07-01
The permutation invariant polynomial-neural network (PIP-NN) method for constructing highly accurate potential energy surfaces (PESs) for gas phase molecules is extended to molecule-surface interaction PESs. The symmetry adaptation in the NN fitting of a PES is achieved by employing as the input symmetry functions that fulfill both the translational symmetry of the surface and permutation symmetry of the molecule. These symmetry functions are low-order PIPs of the primitive symmetry functions containing the surface periodic symmetry. It is stressed that permutationally invariant cross terms are needed to avoid oversymmetrization. The accuracy and efficiency are demonstrated in fitting both a model PES for the H2 + Cu(111) system and density functional theory points for the H2 + Ag(111) system.
Crossing the entropy barrier of dynamical zeta functions
Energy Technology Data Exchange (ETDEWEB)
Aurich, R.; Bolte, J.; Matthies, C.; Sieber, M.; Steiner, F. (Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik)
1992-01-01
Dynamical zeta functions are an important tool to quantize chaotic dynamical systems. The basic quantization rules require the computation of the zeta functions on the real energy axis, where the Euler product representations running over the classical periodic orbits usually do not converge due to the existence of the so-called entropy barrier determined by the topological entropy of the classical system. We shown that the convergence properties of the dynamical zeta functions rewritten as Dirichlet series are governed not only by the well-known topological and metric entropy, but depend crucially on subtle statistical properties of the Maslow indices and of the multiplicities of the periodic orbits that are measured by a new parameter for which we introduce the notion of a third entropy. If and only if the third entropy is nonvanishing, one can cross the entropy barrier; if it exceeds a certain value, one can even compute the zeta function in the physical region by means of a convergent Dirichlet series. A simple statistical model is presented which allows to compute the third entropy. Four examples of chaotic systems are studied in detail to test the model numerically. (orig.).
Some computational formulas related the Riemann zeta-function tails
Directory of Open Access Journals (Sweden)
Hongmin Xu
2016-05-01
Full Text Available Abstract In this paper we present two computational formulae for one kind of reciprocal sums related to the Riemann zeta-function at integer points s = 4 , 5 $s=4,5$ , which answers an open problem proposed by Lin (J. Inequal. Appl. 2016:32, 2016.
Zeta Regularized Product Expressions for Multiple Trigonometric Functions
Kurokawa, Nobushige; Wakayama, Masato
2004-01-01
We introduce a multiple analogue of the gamma function which differs from the one defined by Barnes [B]. Using this function, we give expressions of the multiple sine and cosine functions in terms of zeta regularized products. The expression of the multiple sine function can be interpreted as a reflection formula of this new multiple analogue of the gamma function.
On the zeros of the Epstein zeta function
Mukhopadhyay, Anirban; Srinivas, Kotyada
2011-01-01
In this article, we count the number of consecutive zeros of the Epstein zeta-function, associated to a certain quadratic form, on the critical line with ordinates lying in $[0,T], T$ sufficiently large and which are separated apart by a given positive number $V$.
Masses of the astrometric SB2 \\zeta Ori A
Rivinius, Th; Stahl, O
2010-01-01
We report the first dynamic mass for an O-type supergiant, the interferometrically resolved SB2 system \\zeta Ori A (O9.5Ib+B0/1). The separation of the system excludes any previous mass-transfer, ensuring that the derived masses can be compared to single star evolutionary tracks.
Dynamical zeta functions for piecewise monotone maps of the interval
Ruelle, David
2004-01-01
Consider a space M, a map f:M\\to M, and a function g:M \\to {\\mathbb C}. The formal power series \\zeta (z) = \\exp \\sum ^\\infty _{m=1} \\frac {z^m}{m} \\sum _{x \\in \\mathrm {Fix}\\,f^m} \\prod ^{m-1}_{k=0} g (f^kx) yields an example of a dynamical zeta function. Such functions have unexpected analytic properties and interesting relations to the theory of dynamical systems, statistical mechanics, and the spectral theory of certain operators (transfer operators). The first part of this monograph presents a general introduction to this subject. The second part is a detailed study of the zeta functions associated with piecewise monotone maps of the interval [0,1]. In particular, Ruelle gives a proof of a generalized form of the Baladi-Keller theorem relating the poles of \\zeta (z) and the eigenvalues of the transfer operator. He also proves a theorem expressing the largest eigenvalue of the transfer operator in terms of the ergodic properties of (M,f,g).
Surface-wave potential for triggering tectonic (nonvolcanic) tremor
Hill, D.P.
2010-01-01
Source processes commonly posed to explain instances of remote dynamic triggering of tectonic (nonvolcanic) tremor by surface waves include frictional failure and various modes of fluid activation. The relative potential for Love- and Rayleigh-wave dynamic stresses to trigger tectonic tremor through failure on critically stressed thrust and vertical strike-slip faults under the Coulomb-Griffith failure criteria as a function of incidence angle is anticorrelated over the 15- to 30-km-depth range that hosts tectonic tremor. Love-wave potential is high for strike-parallel incidence on low-angle reverse faults and null for strike-normal incidence; the opposite holds for Rayleigh waves. Love-wave potential is high for both strike-parallel and strike-normal incidence on vertical, strike-slip faults and minimal for ~45?? incidence angles. The opposite holds for Rayleigh waves. This pattern is consistent with documented instances of tremor triggered by Love waves incident on the Cascadia mega-thrust and the San Andreas fault (SAF) in central California resulting from shear failure on weak faults (apparent friction, ????? 0.2). However, documented instances of tremor triggered by surface waves with strike-parallel incidence along the Nankai megathrust beneath Shikoku, Japan, is associated primarily with Rayleigh waves. This is consistent with the tremor bursts resulting from mixed-mode failure (crack opening and shear failure) facilitated by near-lithostatic ambient pore pressure, low differential stress, with a moderate friction coefficient (?? ~ 0.6) on the Nankai subduction interface. Rayleigh-wave dilatational stress is relatively weak at tectonic tremor source depths and seems unlikely to contribute significantly to the triggering process, except perhaps for an indirect role on the SAF in sustaining tremor into the Rayleigh-wave coda that was initially triggered by Love waves.
Improved DFT Potential Energy Surfaces via Improved Densities.
Kim, Min-Cheol; Park, Hansol; Son, Suyeon; Sim, Eunji; Burke, Kieron
2015-10-01
Density-corrected DFT is a method that cures several failures of self-consistent semilocal DFT calculations by using a more accurate density instead. A novel procedure employs the Hartree-Fock density to bonds that are more severely stretched than ever before. This substantially increases the range of accurate potential energy surfaces obtainable from semilocal DFT for many heteronuclear molecules. We show that this works for both neutral and charged molecules. We explain why and explore more difficult cases, for example, CH(+), where density-corrected DFT results are even better than sophisticated methods like CCSD. We give a simple criterion for when DC-DFT should be more accurate than self-consistent DFT that can be applied for most cases.
Stabilized Quasi-Newton Optimization of Noisy Potential Energy Surfaces
Schaefer, Bastian; Roy, Shantanu; Goedecker, Stefan
2014-01-01
Optimizations of atomic positions belong to the most commonly performed tasks in electronic structure calculations. Many simulations like global minimum searches or characterizations of chemical reactions require performing hundreds or thousands of minimizations or saddle computations. To automatize these tasks, optimization algorithms must not only be efficient, but also very reliable. Unfortunately computational noise in forces and energies is inherent to electronic structure codes. This computational noise poses a sever problem to the stability of efficient optimization methods like the limited-memory Broyden-Fletcher-Goldfarb-Shanno algorithm. We here present a technique that allows obtaining significant curvature information of noisy potential energy surfaces. We use this technique to construct both, a stabilized quasi-Newton minimization method and a stabilized quasi-Newton saddle finding approach. We demonstrate with the help of benchmarks that both the minimizer and the saddle finding approach are sup...
Microscopically derived potential energy surfaces from mostly structural considerations
Energy Technology Data Exchange (ETDEWEB)
Ermamatov, M.J. [Instituto de Física, Universidade Federal Fluminense, 24210-340, Niterói, Rio de Janeiro (Brazil); Institute of Nuclear Physics, Ulughbek, Tashkent 100214 (Uzbekistan); Hess, Peter O., E-mail: hess@nucleares.unam.mx [Instituto de Ciencias Nucleares, UNAM, Circuito Exterior, C.U., A.P. 70-543, 04510, Mexico D.F. (Mexico)
2016-08-15
A simple procedure to estimate the quadrupole Potential-Energy-Surface (PES) is presented, using mainly structural information, namely the content of the shell model space and the Pauli exclusion principle. Further microscopic properties are implicitly contained through the use of results from the Möller and Nix tables or experimental information. A mapping to the geometric potential is performed yielding the PES. The General Collective Model is used in order to obtain an estimate on the spectrum and quadrupole transitions, adjusting only the mass parameter. First, we test the conjecture on known nuclei, deriving the PES and compare them to known data. We will see that the PES approximates very well the structure expected. Having acquired a certain confidence, we predict the PES of several chain of isotopes of heavy and super-heavy nuclei and at the end we investigate the structure of nuclei in the supposed island of stability. One of the main points to show is that simple assumptions can provide already important information on the structure of nuclei outside known regions and that spectra and electromagnetic transitions can be estimated without using involved calculations and assumptions. The procedure does not allow to calculate binding energies. The method presented can be viewed as a starting point for further improvements.
On A Rapidly Converging Series For The Riemann Zeta Function
Pichler, Alois
2012-01-01
To evaluate Riemann's zeta function is important for many investigations related to the area of number theory, and to have quickly converging series at hand in particular. We investigate a class of summation formulae and find, as a special case, a new proof of a rapidly converging series for the Riemann zeta function. The series converges in the entire complex plane, its rate of convergence being significantly faster than comparable representations, and so is a useful basis for evaluation algorithms. The evaluation of corresponding coefficients is not problematic, and precise convergence rates are elaborated in detail. The globally converging series obtained allow to reduce Riemann's hypothesis to similar properties on polynomials. And interestingly, Laguerre's polynomials form a kind of leitmotif through all sections.
The Zeta Functions of Complexes from $\\Sp(4)$
Fang, Yang; Wang, Chian-Jen
2011-01-01
Let $F$ be a non-archimedean local field with a finite residue field. To a 2-dimensional finite complex $X_\\Gamma$ arising as the quotient of the Bruhat-Tits building $X$ associated to $\\Sp_4(F)$ by a discrete torsion-free cocompact subgroup $\\Gamma$ of $\\PGSp_4(F)$, associate the zeta function $Z(X_{\\Gamma}, u)$ which counts geodesic tailless cycles contained in the 1-skeleton of $X_{\\Gamma}$. Using a representation-theoretic approach, we obtain two closed form expressions for $Z(X_{\\Gamma}, u)$ as a rational function in $u$. Equivalent statements for $X_{\\Gamma}$ being a Ramanujan complex are given in terms of vertex, edge, and chamber adjacency operators, respectively. The zeta functions of such Ramanujan complexes are distinguished by satisfying the Riemann Hypothesis.
Well-rounded zeta-function of planar arithmetic lattices
Fukshansky, Lenny
2012-01-01
We investigate the properties of the zeta-function of well-rounded sublattices of a fixed arithmetic lattice in the plane. In particular, we show that this function has abscissa of convergence at $s=1$ with a real pole of order 2, improving upon a recent result of S. Kuehnlein. We use this result to show that the number of well-rounded sublattices of a planar arithmetic lattice of index less or equal $N$ is $O(N \\log N)$ as $N \\to \\infty$. To obtain these results, we produce a description of integral well-rounded sublattices of a fixed planar integral well-rounded lattice and investigate convergence properties of a zeta-function of similarity classes of such lattices, building on some previous results of the author.
The angular diameter and distance of the Cepheid Zeta Geminorum
Kervella, P; Perrin, G; Schöller, M; Traub, W A; Lacasse, M D
2001-01-01
Cepheids are the primary distance indicators for extragalactic astronomy and therefore are of very high astrophysical interest. Unfortunately, they are rare stars, situated very far from Earth.Though they are supergiants, their typical angular diameter is only a few milliarcseconds, making them very challenging targets even for long-baseline interferometers. We report observations that were obtained in the K prime band (2-2.3 microns), on the Cepheid Zeta Geminorum with the FLUOR beam combiner, installed at the IOTA interferometer. The mean uniform disk angular diameter was measured to be 1.64 +0.14 -0.16 mas. Pulsational variations are not detected at a significant statistical level, but future observations with longer baselines should allow a much better estimation of their amplitude. The distance to Zeta Gem is evaluated using Baade-Wesselink diameter determinations, giving a distance of 502 +/- 88 pc.
Lecture notes: string theory and zeta-function
Energy Technology Data Exchange (ETDEWEB)
Toppan, Francesco [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil). E-mail: toppan@cbpf.br
2001-11-01
These lecture notes are based on a revised and LaTexed version of the Master thesis defended at ISAS. The research part being omitted, they included a review of the bosonic closed string a la Polyakov and of the one-loop background field method of quantisation defined through the zeta-function. In an appendix some basic features of the Riemann zeta-function are also reviewed. The pedagogical aspects of the material here presented are particularly emphasized. These notes are used, together with the Scherk's article in Rev. Mod. Phys. and the first volume of the Polchinski book, for the mini-course on String Theory (16-hours of lectures) held at CBPF. In this course the Green-Schwarz-Witten two-volumes book is also used for consultative purposes. (author)
Consistency relations and conservation of $\\zeta$ in holographic inflation
Garriga, Jaume
2016-01-01
It is well known that, in single clock inflation, the curvature perturbation $\\zeta$ is constant in time on superhorizon scales. In the standard bulk description this follows quite simply from the local conservation of the energy momentum tensor in the bulk. On the other hand, in a holographic description, the constancy of the curvature perturbation must be related to the properties of the RG flow in the boundary theory. Here, we show that, in single clock holographic inflation, the time independence of correlators of $\\zeta$ follows from the cut-off independence of correlators of the energy momentum tensor in the boundary theory, and from the so-called consistency relations for vertex functions with a soft leg.
He, Dengliang; Liu, Shuxin
2017-02-01
Crystal structure, surface composition, infrared emission properties and surface electrical properties of tourmaline from Guangxi of China, when subjected to heat treatment in air atmosphere had been studied by some methods, including X-ray fluorescence spectrum (XRF), X-ray diffraction (XRD) meter, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), energy dispersion spectroscopy (EDS), scanning electron microscope (SEM) and Zeta potential analyzer, etc. Experimental results show that the unit cell of tourmaline would shrink during heat treatment because Fe2+ were oxidized. Moreover, the Fe3+/Fetotal inside tourmaline can be raised after treatment. Infrared normal total emissivity of tourmaline reaches 0.87, and infrared radiation energy density is 4.56 × 102W/m2. It can maintain excellent infrared emission properties at high temperature. Simultaneously, tourmaline presents negative Zeta potential in the aqueous solution, and its Zeta potential reaches ‑18.04 mV. Zeta potential of tourmaline was increased to ‑24.83 mV after heat treatment at 400∘C, and decrease to ‑11.78 mV after heat treatment at 600∘C. These findings may provide reference data for tourmaline’s application in the field of functional materials.
Distribution of zeta zeroes of Artin--Schreier curves
Bucur, Alina; Feigon, Brooke; Lalin, Matilde; Sinha, Kaneenika
2011-01-01
We study the distribution of the zeroes of the zeta functions of the family of Artin-Schreier curves over $\\mathbb{F}_q$ when $q$ is fixed and the genus goes to infinity. We consider both the global and the mesoscopic regimes, proving that when the genus goes to infinity, the number of zeroes with angles in a prescribed interval of $[-\\pi,\\pi)$ has a standard Gaussian distribution (when properly normalized).
On the Laurent series for the Epstein zeta function
Joyce, G. S.
2016-10-01
The Epstein zeta function ζ d [ M ; s ] ≡ ∑ n ∈ Z d ‧ ( n M n T ) - s 2 , where {M} is a real symmetric and invertible d × d matrix and {n} is a d-dimensional row vector ({n}1,{n}2,\\ldots ,{n}d) with integer coordinates {n}i, is considered. (The prime on the sum indicates that the term {n}={0} should be excluded.) It is known that {\\zeta }d[{M};s] has a Laurent series expansion about the singular point s = d which can be written in the form ζ d [ M ; s ] = ∑ ν = - 1 ∞ A ν [ M ; d ] ( s - d ) ν . In this paper we shall show that the coefficient {A}ν [{M};d] can be accurately calculated using rapidly convergent series which involve the Meijer G-function. Exact formulae are also derived for {A}ν [{M};2] when M = U N ≡ 1 0 0 N , with N=1,2,\\ldots . The results for {A}0[{{U}}N;2] are then used to establish several mathematical identities involving summations of generalized Stieltjes constants. Next the Laurent series for {\\zeta }d[{{I}}d;s], where {{I}}d is the d × d unit matrix, is briefly discussed for the cases d=3,4,6 and 8. Finally, a new application of the results in lattice statistics is described.
Aharonovich, Igal
2016-01-01
We present a simple method to expedite simulation of quantum wave-packet dynamics by more than a factor of $2$ with the Strang split-operator propagation. Dynamics of quantum wave-packets are often evaluated using the the \\emph{Strang} split-step propagation, where the kinetic part of the Hamiltonian $\\hat{T}$ and the potential part $\\hat{V}$ are piecewise integrated according to $e^{- i \\hat{H} \\delta t} \\approx e^{- i \\hat{V} \\delta t/2} e^{- i \\hat{T}\\delta t} e^{- i \\hat{V} \\delta t/2}$, which is accurate to second order in the propagation time $\\delta t$. In molecular quantum dynamics, the potential propagation occurs over multiple coupled potential surfaces and requires matrix exponentiation for each position in space and time which is computationally demanding. Our method employs further splitting of the potential matrix $\\hat{V}$ into a diagonal space dependent part $\\hat{V}_{D}(R)$ and an off-diagonal time-dependent coupling-field $\\hat{V}_{OD}(t)$, which then requires only a single matrix exponentia...
Shang, Cheng; Liu, Zhi-Pan
2012-07-10
To predict the chemical activity of new matter is an ultimate goal in chemistry. The identification of reaction pathways using modern quantum mechanics calculations, however, often requires a high demand in computational power and good chemical intuition on the reaction. Here, a new reaction path searching method is developed by combining our recently developed transition state (TS) location method, namely, the constrained Broyden dimer method, with a basin-filling method via bias potentials, which allows the system to walk out from the energy traps at a given reaction direction. In the new method, the reaction path searching starts from an initial state without the need for preguessing the TS-like or final state structure and can proceed iteratively to the final state by locating all related TSs and intermediates. In each elementary reaction step, a reaction direction, such as a bond breaking, needs to be specified, the information of which is refined and preserved as a normal mode through biased dimer rotation. The method is tested successfully on the Baker reaction system (50 elementary reactions) with good efficiency and stability and is also applied to the potential energy surface exploration of multistep reaction processes in the gas phase and on the surface. The new method can be applied for the computational screening of new catalytic materials with a minimum requirement of chemical intuition.
Landau-Siegel zeros and zeros of the derivative of the Riemann zeta function
Farmer, David W
2010-01-01
We show that if the derivative of the Riemann zeta function has sufficiently many zeros close to the critical line, then the zeta function has many closely spaced zeros. This gives a condition on the zeros of the derivative of the zeta function which implies a lower bound of the class numbers of imaginary quadratic fields.
The cyclic AMP response element modulator regulates transcription of the TCR zeta-chain
Tenbrock, K; Kyttaris, VC; Ahlmann, M; Ehrchen, JA; Tolnay, M; Melkonyan, H; Mawrin, C; Roth, J; Sorg, C; Juang, YT; Tsokos, GC
2005-01-01
Systemic lupus erythematusus T cells display decreased amounts of TCR zeta mRNA that results in part from limited binding of the transcriptional enhancer Elf-1 to the TCR zeta promoter. We have identified a new cis-binding site for the cAMP response element (CRE) modulator (CREM) on the TCR zeta pro
Surface potential determination in metal-oxide-semiconductor capacitors
Moragues, J. M.; Ciantar, E.; Jerisian, R.; Sagnes, B.; Oualid, J.
1994-11-01
Different methods using the relationship between surface potential Psi(sub S) and gate bias V(sub G) in metal-oxide-semiconductor (MOS) capacitors have been compared. These methods can be applied even if the doping profile is very abrupt and the interface state density very high. The shifts of midgap, flatband, and threshold voltages, observed after Fowler-Nordheim electron injection, and deduced from the various Psi(sub S(V (sub G)) relationships obtained by these different methods, are in good agreement. These shifts give the number of effective oxide trapped charges (N(sub ox)) per unit area and acceptor-like and donor-like interface states (N(sub SS)A and N(sub SS)D) which are created during the electron injection. We reveal that the number of positive charges created in the gate oxide, unlike the number of generated interface states, strongly depends on the position of the post-metallization annealing step in the process. After relaxation of the stressed MOS capacitors, most of the generated positive charges can be attributed, in the MOS capacitors studied, to hydrogen-related species. It seems that the interface states are essentially created by the recombination of holes generated by electron impact.
Potential therapeutic applications of microbial surface-active compounds
Directory of Open Access Journals (Sweden)
Letizia Fracchia
2015-08-01
Full Text Available Numerous investigations of microbial surface-active compounds or biosurfactants over the past two decades have led to the discovery of many interesting physicochemical and biological properties including antimicrobial, anti-biofilm and therapeutic among many other pharmaceutical and medical applications. Microbial control and inhibition strategies involving the use of antibiotics are becoming continually challenged due to the emergence of resistant strains mostly embedded within biofilm formations that are difficult to eradicate. Different aspects of antimicrobial and anti-biofilm control are becoming issues of increasing importance in clinical, hygiene, therapeutic and other applications. Biosurfactants research has resulted in increasing interest into their ability to inhibit microbial activity and disperse microbial biofilms in addition to being mostly nontoxic and stable at extremes conditions. Some biosurfactants are now in use in clinical, food and environmental fields, whilst others remain under investigation and development. The dispersal properties of biosurfactants have been shown to rival that of conventional inhibitory agents against bacterial, fungal and yeast biofilms as well as viral membrane structures. This presents them as potential candidates for future uses in new generations of antimicrobial agents or as adjuvants to other antibiotics and use as preservatives for microbial suppression and eradication strategies.
Measuring differential rotation of the K-giant $\\zeta$\\,And
K\\Hovári, Zs; Kriskovics, L; Vida, K; Donati, J -F; Coroller, H Le; Pedretti, J D Monnier E; Petit, P
2012-01-01
We investigate the temporal spot evolution of the K-giant component in the RS CVn-type binary system $\\zeta$\\,Andromedae to establish its surface differential rotation. Doppler imaging is used to study three slightly overlapping spectroscopic datasets, obtained independently at three different observing sites. Each dataset covers one full stellar rotation with good phase coverage, and in total, results in a continuous coverage of almost three stellar rotations ($P_{\\rm rot}=$17.8\\,d). Therefore, these data are well suited for reconstructing surface temperature maps and studying temporal evolution in spot configurations. Surface differential rotation is measured by the means of cross-correlation of all the possible image pairs. The individual Doppler reconstructions well agree in the revealed spot pattern, recovering numerous low latitude spots with temperature contrasts of up to $\\approx$1000\\,K with respect to the unspotted photosphere, and also an asymmetric polar cap which is diminishing with time. Our det...
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Hopper, D.G.
1980-05-01
The ground state potential energy surface for the nitrogen dioxide positive ion, NO/sup +//sub 2/X /sup 1/..sigma../sup +//sub g/(..sigma../sup +/,A/sub 1/,A'), has been scanned with a correlated wave function to obtain directly, for the first time, the gas phase equilibrium geometry, force constants, vibrational frequencies, and dipole moment function. The wave function for this scan was constructed from a double-zeta plus polarization one-electron basis with a 12 configuration MCSCF determination of the orbital basis for a full valence /sup 1/..sigma../sup +//sub g/ configuration interaction expansion. The calculated equilibrium bond length is 1.12 A. The vibrational frequencies are computed to be ..nu../sub 1/=1514, ..nu../sub 2/=679, and ..nu../sub 3/=2614 cm/sup -1/ The present ab initio results differ significantly from crystalline spectroscopic studies and are, thus, the best values available for the gas phase vibrational frequencies. The dipole moment function is nonzero at the ..sigma../sup +/, A/sub 1/, and A' geometries included in the potential surface scan, and is obtained here to provide for the future a priori calculation of the infrared band intensities.
Proof of generalized Riemann hypothesis for Dedekind zetas and Dirichlet L-functions
Mcadrecki, Andrzej
2007-01-01
A short proof of the generalized Riemann hypothesis (gRH in short) for zeta functions $\\zeta_{k}$ of algebraic number fields $k$ - based on the Hecke's proof of the functional equation for $\\zeta_{k}$ and the method of the proof of the Riemann hypothesis derived in [$M_{A}$] (algebraic proof of the Riemann hypothesis) is given. The generalized Riemann hypothesis for Dirichlet L-functions is an immediately consequence of (gRH) for $\\zeta_{k}$ and suitable product formula which connects the Dedekind zetas with L-functions.
A surface study of mercury-cadmium-telluride
Lopes, V. C.
1985-12-01
Single crystals of Hg (sub 1-x) Cd (sub x) Te were studied to determine how changes in the surface conditions affected electrical properties, infrared detector grade material was used to examine the effects of changes in the surface charge density on electrical l/f noise. The surface charge density which was controlled by the pH of the aqueous solution was measured in a zeta meter which operated much like a Millikan oil drop experiment. The electrophoresis zeta potential measurements on (HgCd)Te have identified the active surface oxide as TeO2 and has also revealed information on the surface chemistry. Electrical l/f noise in-(HgCd)Te was found to be dominated by bulk and not surface effects at room temperature. Laser Raman and Auger spectroscopy were used to assess mechanical surface damage and anodic oxide composition.
Effects of microorganisms on surface properties of chalcopyrite and bioleaching
Institute of Scientific and Technical Information of China (English)
CHEN Ming-lian; ZHANG Lin; GU Guo-hua; HU Yue-hua; SU Li-jun
2008-01-01
The alteration of surface properties of chalcopyrite after biological conditioning with Acidithiobacillus ferrooxidans and Acidithiobacillus caldus was evaluated by Zeta-potential,adsorption studies,FT-IR spectra and contact angle measurement.The Zeta-potential studies show that the iso-electric point(IEP) of chalcopyrite after bacterial treatment moves towards the IEP of pure cells,indicating the adsorption of cells on chalcopyrite surface.The FT-IR spectra of chalcopyrite treated with bacterial cells show the presence of the cell functional groups signifying cells adsorption.Due to the formation of elemental sulfur and intermediate copper sulphides on chalcopyrite surface,the contact angle and surface hydrophobicity of chalcopyrite increase at the initial bioleaching stage.Chalcopyrite bioleaching by Acidithiobacillus ferrooxidans has higher copper extraction,which agrees with the fact that Acidithiobacillus ferrooxidans adsorbed on chalcopyrite surface is much more than Acidithiobacillus caldus.The results support the direct mechanism of sulfide oxidations in bioleaching chalcopyrite.
Surface grafted polymer brushes: potential applications in dengue biosensors
Energy Technology Data Exchange (ETDEWEB)
Baratela, Fernando Jose Costa; Higa, Olga Zazuco, E-mail: ozahiga@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Faria, Henrique Antonio Mendonca de; Queiroz, Alvaro Antonio Alencar de, E-mail: alencar@unifei.edu.br [Universidade Federal de Itajuba (UNIFEI), Itajuba, MG (Brazil). Instituto de Fisica e Quimica
2013-07-01
A polymer brush membrane-based ultrasensitive biosensor for dengue diagnosis was constructed using poly(hydroxyethyl methacrylate) (PHEMA) brushes immobilized onto low density polyethylene (LDPE) films. LDPE surface films were initially modified by Ar{sup +} ion irradiation to activate the polymer surface. Subsequently, graft polymerization of 2-hydroxyethyl methacrylate onto the activated LDPE surface was carried out under aqueous conditions to create patterned polymer brushes of PHEMA. The grafted PHEMA brushes were characterized by Fourier transform-infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and contact angle analysis. The SEM observations showed that selective surface activation with Ar+ implantation and graft polymerization on the selectively activated surface had occurred. The PHEMA brushes were electrically characterized in the presence of concentrations of human immunoglobulin (IgG). The proposed amperometric biosensor was successfully used for determination of IgG in physiologic samples with excellent responses. (author)
Local zeta factors and geometries under Spec Z
Manin, Yu I.
2016-08-01
The first part of this note shows that the odd-period polynomial of each Hecke cusp eigenform for the full modular group produces via the Rodriguez-Villegas transform ([1]) a polynomial satisfying the functional equation of zeta type and having non-trivial zeros only in the middle line of its critical strip. The second part discusses the Chebyshev lambda-structure of the polynomial ring as Borger's descent data to \\mathbf{F}_1 and suggests its role in a possible relation of the Γ\\mathbf{R}-factor to 'real geometry over \\mathbf{F}_1' (cf. [2]).
Exploring the Riemann zeta function 190 years from Riemann's birth
Nikeghbali, Ashkan; Rassias, Michael
2017-01-01
This book is concerned with the Riemann Zeta Function, its generalizations, and various applications to several scientific disciplines, including Analytic Number Theory, Harmonic Analysis, Complex Analysis and Probability Theory. Eminent experts in the field illustrate both old and new results towards the solution of long-standing problems and include key historical remarks. Offering a unified, self-contained treatment of broad and deep areas of research, this book will be an excellent tool for researchers and graduate students working in Mathematics, Mathematical Physics, Engineering and Cryptography.
The Riemann zeta-function theory and applications
Ivic, Aleksandar
2003-01-01
""A thorough and easily accessible account.""-MathSciNet, Mathematical Reviews on the Web, American Mathematical Society. This extensive survey presents a comprehensive and coherent account of Riemann zeta-function theory and applications. Starting with elementary theory, it examines exponential integrals and exponential sums, the Voronoi summation formula, the approximate functional equation, the fourth power moment, the zero-free region, mean value estimates over short intervals, higher power moments, and omega results. Additional topics include zeros on the critical line, zero-density estim
Understanding the photometric variability of {\\zeta} Ori Aa
Buysschaert, B; Ramiaramanantsoa, T; Richardson, N D; David-Uraz, A; Moffat, A F J
2016-01-01
We studied the variability of the magnetic O-type supergiant $\\zeta$ Ori Aa using multi-colour BRITE photometry. We confirmed the known rotation frequency $f_{\\rm rot} = 0.15 \\pm 0.02$ c/d, and detected some of its higher harmonics, of which $4f_{\\rm rot}$ is compatible with the known DAC recurrence timescale. Thanks to simultaneous high-resolution CHIRON spectroscopy, we could identify another frequency $f_{\\rm env} = 0.10 \\pm 0.02$ c/d, caused by the circumstellar environment. Variations in the circumstellar environment are believed to cause the observed difference between the BRITE lightcurves.
Sumas de Gauss y funciones zeta de hipersuperficies diagonales
Chiara Llanos, Olmo
2017-01-01
A lo largo de este trabajo abordaremos algunos casos particulares de las conjeturas de Weil. En primer lugar estudiaremos la definición de función zeta de una variedad y la formulación de las conjeturas de Weil, con su respectiva motivación. Seguidamente, introduciremos toda la teoría de sumas de Gauss y de Jacobi, partiendo de la base de la teoría de caracteres de un grupo abeliano, para obtener resultados sobre el cálculo del número de puntos de ciertas variedades sobre cuerpos de caracterí...
A global potential energy surface and dipole moment surface for silane.
Owens, Alec; Yurchenko, Sergei N; Yachmenev, Andrey; Thiel, Walter
2015-12-28
A new nine-dimensional potential energy surface (PES) and dipole moment surface (DMS) for silane have been generated using high-level ab initio theory. The PES, CBS-F12(HL), reproduces all four fundamental term values for (28)SiH4 with sub-wavenumber accuracy, resulting in an overall root-mean-square error of 0.63 cm(-1). The PES is based on explicitly correlated coupled cluster calculations with extrapolation to the complete basis set limit, and incorporates a range of higher-level additive energy corrections to account for core-valence electron correlation, higher-order coupled cluster terms, and scalar relativistic effects. Systematic errors in computed intra-band rotational energy levels are reduced by empirically refining the equilibrium geometry. The resultant Si-H bond length is in excellent agreement with previous experimental and theoretical values. Vibrational transition moments, absolute line intensities of the ν3 band, and the infrared spectrum for (28)SiH4 including states up to J = 20 and vibrational band origins up to 5000 cm(-1) are calculated and compared with available experimental results. The DMS tends to marginally overestimate the strength of line intensities. Despite this, band shape and structure across the spectrum are well reproduced and show good agreement with experiment. We thus recommend the PES and DMS for future use.
A global potential energy surface and dipole moment surface for silane
Energy Technology Data Exchange (ETDEWEB)
Owens, Alec, E-mail: owens@mpi-muelheim.mpg.de [Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr (Germany); Department of Physics and Astronomy, University College London, Gower Street, WC1E 6BT London (United Kingdom); Yurchenko, Sergei N.; Yachmenev, Andrey [Department of Physics and Astronomy, University College London, Gower Street, WC1E 6BT London (United Kingdom); Thiel, Walter [Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr (Germany)
2015-12-28
A new nine-dimensional potential energy surface (PES) and dipole moment surface (DMS) for silane have been generated using high-level ab initio theory. The PES, CBS-F12{sup HL}, reproduces all four fundamental term values for {sup 28}SiH{sub 4} with sub-wavenumber accuracy, resulting in an overall root-mean-square error of 0.63 cm{sup −1}. The PES is based on explicitly correlated coupled cluster calculations with extrapolation to the complete basis set limit, and incorporates a range of higher-level additive energy corrections to account for core-valence electron correlation, higher-order coupled cluster terms, and scalar relativistic effects. Systematic errors in computed intra-band rotational energy levels are reduced by empirically refining the equilibrium geometry. The resultant Si–H bond length is in excellent agreement with previous experimental and theoretical values. Vibrational transition moments, absolute line intensities of the ν{sub 3} band, and the infrared spectrum for {sup 28}SiH{sub 4} including states up to J = 20 and vibrational band origins up to 5000 cm{sup −1} are calculated and compared with available experimental results. The DMS tends to marginally overestimate the strength of line intensities. Despite this, band shape and structure across the spectrum are well reproduced and show good agreement with experiment. We thus recommend the PES and DMS for future use.
Blundell, Emma L C J; Healey, Matthew J; Holton, Elizabeth; Sivakumaran, Muttuswamy; Manstana, Sarabjit; Platt, Mark
2016-08-01
The zeta potential of the protein corona around carboxyl particles has been measured using tunable resistive pulse sensing (TRPS). A simple and rapid assay for characterising zeta potentials within buffer, serum and plasma is presented monitoring the change, magnitude and distribution of proteins on the particle surface. First, we measure the change in zeta potential of carboxyl-functionalised nanoparticles in solutions that contain biologically relevant concentrations of individual proteins, typically constituted in plasma and serum, and observe a significant difference in distributions and zeta values between room temperature and 37 °C assays. The effect is protein dependent, and the largest difference between the two temperatures is recorded for the γ-globulin protein where the mean zeta potential changes from -16.7 to -9.0 mV for 25 and 37 °C, respectively. This method is further applied to monitor particles placed into serum and/or plasma. A temperature-dependent change is again observed with serum showing a 4.9 mV difference in zeta potential between samples incubated at 25 and 37 °C; this shift was larger than that observed for samples in plasma (0.4 mV). Finally, we monitor the kinetics of the corona reorientation for particles initially placed into serum and then adding 5 % (V/V) plasma. The technology presented offers an interesting insight into protein corona structure and kinetics of formation measured in biologically relevant solutions, i.e. high protein, high salt levels, and its particle-by-particle analysis gives a measure of the distribution of particle zeta potential that may offer a better understanding of the behaviour of nanoparticles in solution. Graphical Abstract The relative velocity of a nanoparticle as it traverses a nanopore can be used to determine its zeta potential. Monitoring the changes in translocation speeds can therefore be used to follow changes to the surface chemistry/composition of 210 nm particles that were placed
Directory of Open Access Journals (Sweden)
Nasr Esfahani Mohammad Hossein
2016-07-01
Full Text Available Background Selection of sperm for intra-cytoplasmic sperm injection (ICSI is usually considered as the ultimate technique to alleviate male-factor infertility. In routine ICSI, selection is based on morphology and viability which does not necessarily preclude the chance injection of DNA-damaged or apoptotic sperm into the oocyte. Sperm with high negative surface electrical charge, named “Zeta potential”, are mature and more likely to have intact chromatin. In addition, X-bearing spermatozoa carry more negative charge. Therefore, we aimed to compare the clinical outcomes of Zeta procedure with routine sperm selection in infertile men candidate for ICSI. Materials and Methods From a total of 203 ICSI cycles studied, 101 cycles were allocated to density gradient centrifugation (DGC/Zeta group and the remaining 102 were included in the DGC group in this prospective study. Clinical outcomes were com- pared between the two groups. The ratios of Xand Y bearing sperm were assessed by fluorescence in situ hybridization (FISH and quantitative polymerase chain reaction (qPCR methods in 17 independent semen samples. Results In the present double-blind randomized clinical trial, a significant increase in top quality embryos and pregnancy rate were observed in DGC/Zeta group compared to DGC group. Moreover, sex ratio (XY/XX at birth significantly was lower in the DGC/Zeta group compared to DGC group despite similar ratio of X/Y bearings sper- matozoa following Zeta selection. Conclusion Zeta method not only improves the percentage of top embryo quality and pregnancy outcome but also alters the sex ratio compared to the conventional DGC method, despite no significant change in the ratio of Xand Ybearing sperm population (Registration number: IRCT201108047223N1.
Riemann Hypothesis and Random Walks: the Zeta case
LeClair, André
2016-01-01
In previous work it was shown that if certain series based on sums over primes of non-principal Dirichlet characters have a conjectured random walk behavior, then the Euler product formula for its $L$-function is valid to the right of the critical line $\\Re (s) > 1/2$, and the Riemann Hypothesis for this class of $L$-functions follows. Building on this work, here we propose how to extend this line of reasoning to the Riemann zeta function and other principal Dirichlet $L$-functions. We use our results to argue that $ S_\\delta (t) \\equiv \\lim_{\\delta \\to 0^+} \\dfrac{1}{\\pi} \\arg \\zeta (\\tfrac{1}{2}+ \\delta + i t ) = O(1)$, and that it is nearly always on the principal branch. We conjecture that a 1-point correlation function of the Riemann zeros has a normal distribution. This leads to the construction of a probabilistic model for the zeros. Based on these results we describe a new algorithm for computing very high Riemann zeros as a kind of stochastic process, and we calculate the $10^{100}$-th zero to over 1...
Potencial zeta de sulfatos de de bario y de estroncio
Directory of Open Access Journals (Sweden)
Edgar Delgado M.
2010-06-01
Full Text Available Por medio de la electroforesis se determinó las movilidades electroforéticas y los potenciales zeta del sulfato de bario a 25,0 °C como función de la fuerza iónica de NaCI, así como del Sulfato de estroncio en función de la fuerza iónica del cloruro de sodio y del pH. Se encontró que el amento de la fuerza iónica de NaCI causa un cambio del Potencial Zeta negativo del sulfato de estroncio a positivo con valor cero a aprox. 0,06 de fuerza iónica. El P.Z. del sulfato de estroncio es positivo a pH inferiores a aprox. 2,5 y negativo a pH superiores. El sulfato de bario presenta P.Z. negativas a fuerza iónicas de NaCI inferiores a aprox. 0.06 y PZ positivos a fuerzas iónicas mayores
Energy Technology Data Exchange (ETDEWEB)
Verissimo, Tanira V. [School of Health Sciences, University of Brasilia, Brasilia (Brazil); Laboratory of Photochemistry and Nanobiotechnology, Faculty of Ceilandia, University of Brasilia, Brasilia (Brazil); Santos, Naiara T. [School of Health Sciences, University of Brasilia, Brasilia (Brazil); Silva, Jaqueline R.; Azevedo, Ricardo B. [Institute of Biological Sciences, University of Brasilia, Brasilia (Brazil); Gomes, Anderson J., E-mail: ajgomes@unb.br [School of Health Sciences, University of Brasilia, Brasilia (Brazil); Laboratory of Photochemistry and Nanobiotechnology, Faculty of Ceilandia, University of Brasilia, Brasilia (Brazil); Lunardi, Claure N., E-mail: clunardi@unb.br [School of Health Sciences, University of Brasilia, Brasilia (Brazil); Laboratory of Photochemistry and Nanobiotechnology, Faculty of Ceilandia, University of Brasilia, Brasilia (Brazil)
2016-08-01
The surface of gold nanoparticles (AuNP) was modified, improving their interaction with neutral red (NR), by using sodium thioglycolate (TGA) as a covering agent. The resulting NR-AuNPTGA system was evaluated as a potential drug delivery system for photodynamic therapy (PDT). The associations of NR with the gold nanoparticles were evaluated using UV-vis spectrometry and measurement of their zeta potential and size distribution. The toxicity and phototoxicity of NR, AuNPTGA and NR-AuNPTGA were evaluated in NIH-3T3 fibroblast and 4T1 tumor cell lines. The compounds NR and NR-AuNPTGA induced toxicity in 4T1 tumor cells and NIH-3T3 fibroblasts under visible light irradiation. Modification of the surface of AuNP with TGA prevented nanoparticle aggregation and allowed greater association with NR molecules than for naked AuNP. The photosensitizer (PS) characteristics were not affected by its association with the modified surface of the gold nanoparticles, leading to a reduction of cell viability in both cell lines assayed. This NR-AuNPTGA system is a promising drug delivery system for photodynamic cancer therapy. - Highlights: • Modified gold nanoparticle (AuNP) by sodium thioglicolate (TGA) prevents aggregation. • Neutral red (NR) adsorbed on the surface of modified gold nanoparticles (AuNPTGA). • AuNPTGA is suitable as a platform to deliver the NR under irradiation process. • Photodamage of 90% was achieved by NR added to AuNPTGA in 4T1 and NIH-3T3 cells.
Abramovici, Hanan; Hogan, Angela B; Obagi, Christopher; Topham, Matthew K; Gee, Stephen H
2003-11-01
Syntrophins are scaffolding proteins that link signaling molecules to dystrophin and the cytoskeleton. We previously reported that syntrophins interact with diacylglycerol kinase-zeta (DGK-zeta), which phosphorylates diacylglycerol to yield phosphatidic acid. Here, we show syntrophins and DGK-zeta form a complex in skeletal muscle whose translocation from the cytosol to the plasma membrane is regulated by protein kinase C-dependent phosphorylation of the DGK-zeta MARCKS domain. DGK-zeta mutants that do not bind syntrophins were mislocalized, and an activated mutant of this sort induced atypical changes in the actin cytoskeleton, indicating syntrophins are important for localizing DGK-zeta and regulating its activity. Consistent with a role in actin organization, DGK-zeta and syntrophins were colocalized with filamentous (F)-actin and Rac in lamellipodia and ruffles. Moreover, extracellular signal-related kinase-dependent phosphorylation of DGK-zeta regulated its association with the cytoskeleton. In adult muscle, DGK-zeta was colocalized with syntrophins on the sarcolemma and was concentrated at neuromuscular junctions (NMJs), whereas in type IIB fibers it was found exclusively at NMJs. DGK-zeta was reduced at the sarcolemma of dystrophin-deficient mdx mouse myofibers but was specifically retained at NMJs, indicating that dystrophin is important for the sarcolemmal but not synaptic localization of DGK-zeta. Together, our findings suggest syntrophins localize DGK-zeta signaling complexes at specialized domains of muscle cells, which may be critical for the proper control of lipid-signaling pathways regulating actin organization. In dystrophic muscle, mislocalized DGK-zeta may cause abnormal cytoskeletal changes that contribute to disease pathogenesis.
Faramaz, V.; Beust, H.; Thebault, P.; Augereau, J.-C.; Bonsor, A.; delBurgo, C.; Ertel, S.; Marshall, J. P.; Milli, J.; Montesinos, B.; Mora, A.; Bryden, G.; Danchi, William C.; Eiroa, C.; White, G. J.; Wolf, S.
2014-01-01
Context. Imaging of debris disks has found evidence for both eccentric and offset disks. One hypothesis is that they provide evidence for massive perturbers, for example, planets or binary companions, which sculpt the observed structures. One such disk was recently observed in the far-IR by the Herschel Space Observatory around Zeta2 Reticuli. In contrast with previously reported systems, the disk is significantly eccentric, and the system is several Gyr old. Aims. We aim to investigate the long-term evolution of eccentric structures in debris disks caused by a perturber on an eccentric orbit around the star. We hypothesise that the observed eccentric disk around Zeta2 Reticuli might be evidence of such a scenario. If so, we are able to constrain the mass and orbit of a potential perturber, either a giant planet or a binary companion. Methods. Analytical techniques were used to predict the effects of a perturber on a debris disk. Numerical N-body simulations were used to verify these results and further investigate the observable structures that may be produced by eccentric perturbers. The long-term evolution of the disk geometry was examined, with particular application to the Zeta2 Reticuli system. In addition, synthetic images of the disk were produced for direct comparison with Herschel observations. Results. We show that an eccentric companion can produce both the observed offsets and eccentric disks. These effects are not immediate, and we characterise the timescale required for the disk to develop to an eccentric state (and any spirals to vanish). For Zeta2 Reticuli, we derive limits on the mass and orbit of the companion required to produce the observations. Synthetic images show that the pattern observed around Zeta2 Reticuli can be produced by an eccentric disk seen close to edge-on, and allow us to bring additional constraints on the disk parameters of our model (disk flux and extent). Conclusions. We conclude that eccentric planets or stellar companions
Li, Jun; Xie, Changjian; Guo, Hua
2017-08-30
A full dimensional accurate potential energy surface (PES) for the C((3)P) and H2O reaction is developed based on ∼34 000 data points calculated at the level of the explicitly correlated unrestricted coupled cluster method with single, double, and perturbative triple excitations with the augmented correlation-consistent polarized triple zeta basis set (CCSD(T)-F12a/AVTZ). The PES is invariant with respect to the permutation of the two hydrogen atoms and the total root mean square error (RMSE) of the fit is only 0.31 kcal mol(-1). The PES features two barriers in the entrance channel and several potential minima, as well as multiple product channels. The rate coefficients of this reaction calculated using a transition-state theory and quasi-classical trajectory (QCT) method are small near room temperature, consistent with experiments. The reaction dynamics is also investigated with QCT on the new PES, which found that the reactivity is constrained by the entrance barriers and the final product branching is not statistical.
Microscopic Calculation of IBM Parameters by Potential Energy Surface Mapping
Bentley, I
2011-01-01
A coherent state technique is used to generate an Interacting Boson Model (IBM) Hamiltonian energy surface that simulates a mean field energy surface. The method presented here has some significant advantages over previous work. Specifically, that this can be a completely predictive requiring no a priori knowledge of the IBM parameters. The technique allows for the prediction of the low lying energy spectra and electromagnetic transition rates which are of astrophysical interest. Results and comparison with experiment are included for krypton, molybdenum, palladium, cadmium, gadolinium, dysprosium and erbium nuclei.
VANDERMEI, HC; VANDEBELTGRITTER, B; BUSSCHER, HJ
1995-01-01
Microbial adhesion to hydrocarbons (MATH) is generally considered to be a measure of the organisms cell surface hydrophobicity. Recent observations that the zeta potentials of hydrocarbons can be highly negative in the various solutions commonly used in MATH, have suggested that MATH may measure a
Estimates of global dew collection potential on artificial surfaces
National Research Council Canada - National Science Library
Vuollekoski, H; Vogt, M; Sinclair, V. A; Duplissy, J; Järvinen, H; Kyrö, E.-M; Makkonen, R; Petäjä, T; Prisle, N. L; Räisänen, P; Sipilä, M; Ylhäisi, J; Kulmala, M
2015-01-01
The global potential for collecting usable water from dew on an artificial collector sheet was investigated by utilizing 34 years of meteorological reanalysis data as input to a dew formation model...
Estimates of global dew collection potential on artificial surfaces
Vuollekoski, H.; Vogt, M.; Sinclair, V. A.; Duplissy, J; Järvinen, H; Kyrö, E.-M.; R. Makkonen; T. Petäjä; N. L. Prisle; Räisänen, P.; M. Sipilä; J. Ylhäisi; Kulmala, M
2015-01-01
The global potential for collecting usable water from dew on an artificial collector sheet was investigated by utilizing 34 years of meteorological reanalysis data as input to a dew formation model. Continental dew formation was found to be frequent and common, but daily yields were mostly below 0.1 mm. Nevertheless, some water-stressed areas such as parts of the coastal regions of northern Africa and the Arabian Peninsula show potential for large-scale dew harvesting, as th...
SURFACE-MODIFICATION OF FINE RED IRON OXIDE PIGMENT
Institute of Scientific and Technical Information of China (English)
Shuilin Zheng; Qinghui Zhang
2003-01-01
Surface-modification of fine red iron oxide pigment was carried out in an aqueous solution of sodium polyacrylate. The sedimentation time of modified samples in water increased from 1.05 to 264.4 hours while the particle size (d50) decreased from 1.09 to 0.85 μm, and the tinting strength increased from 100 to 115. The surface-modification as well as the dispersing and stabilizing mechanisms in aqueous solution of the samples were studied by means of IR,Thermal analysis and Zeta potential. The results showed that the modifier molecules acted on the surface of the particles by chemical and physical adsorption, and after the particles were dispersed in aqueous solution, endowing the particle surface with a relatively high negative Zeta potential, thus enhancing electrostatic and steric repulsion between particles for their effective stabilization.
Aguedo, Mario; Waché, Yves; Belin, Jean-Marc; Teixeira, José A
2005-03-01
The surface of the lipid-degrading yeast, Yarrowia lipolytica, was characterized by contact angle and zeta potential (zeta) measurements. The cells were mainly hydrophilic with a negative charge that was only affected from pH 2 to 4. To study the effects of the surface charges on the biotransformation of methyl ricinoleate into the aroma compound, gamma-decalactone, the zeta values of the substrate droplets were modified by adding a cationic surfactant into the medium at concentrations that did not diminish cell viability: the adhesion of the lipid substrate to the cells was increased but not the overall performance of the process, therefore the adhesion is not the rate limiting here. Our methodology offers interesting perspectives for further applications.
Zeta diversity as a concept and metric that unifies incidence-based biodiversity patterns.
Hui, Cang; McGeoch, Melodie A
2014-11-01
Patterns in species incidence and compositional turnover are central to understanding what drives biodiversity. Here we propose zeta (ζ) diversity, the number of species shared by multiple assemblages, as a concept and metric that unifies incidence-based diversity measures, patterns, and relationships. Unlike other measures of species compositional turnover, zeta diversity partitioning quantifies the complete set of diversity components for multiple assemblages, comprehensively representing the spatial structure of multispecies distributions. To illustrate the application and ecological value of zeta diversity, we show how it scales with sample number, grain, and distance. Zeta diversity reconciles several different biodiversity patterns, including the species accumulation curve, the species-area relationship, multispecies occupancy patterns, and scaling of species endemism. Exponential and power-law forms of zeta diversity are associated with stochastic versus niche assembly processes. Zeta diversity may provide new insights on biodiversity patterns, the processes driving them, and their response to environmental change.
Potential energy surface of the photolysis of isocyanic acid HNCO
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The dissociation curves of the photolysis of the isocyanic acidHNCOHN+CO corresponding to the ground state (S0), the first triplet excited state (T1) and the first singlet excited state (S1) have been studied respectively at the UHF/6-311G** and CIS/6-311G** levels using ab initio method. The energy surface crossing points, S1/T1, T1/S0 and S1/S0, have been found and the characteristics of the energy minimum crossing point were given, based on which, the changes of the crossing points' geometries along the lower electronic energy surface and its end-result have been located according to the steepest descent principle. The computational result indicates that the photolysis of the isocyanic acid HNCOHN+CO has three competitive reaction channels ((A)-(C)), and from the kinetic piont of view, channel (A) is the most advantageous.
Evolution of the potential-energy surface of amorphous silicon
Kallel, Houssem; Mousseau, Normand; Schiettekatte, François
2010-01-01
The link between the energy surface of bulk systems and their dynamical properties is generally difficult to establish. Using the activation-relaxation technique (ART nouveau), we follow the change in the barrier distribution of a model of amorphous silicon as a function of the degree of relaxation. We find that while the barrier-height distribution, calculated from the initial minimum, is a unique function that depends only on the level of distribution, the reverse-barrier height distributio...
Adsorption of lysozyme on base metal surfaces in the presence of an external electric potential.
Ei Ei, Htwe; Nakama, Yuhi; Tanaka, Hiroshi; Imanaka, Hiroyuki; Ishida, Naoyuki; Imamura, Koreyoshi
2016-11-01
The impact of external electric potential on the adsorption of a protein to base metal surfaces was examined. Hen egg white lysozyme (LSZ) and six types of base metal plates (stainless steel SUS316L (St), Ti, Ta, Zr, Cr, or Ni) were used as the protein and adsorption surface, respectively. LSZ was allowed to adsorb on the surface under different conditions (surface potential, pH, electrolyte type and concentration, surface material), which was monitored using an ellipsometer. LSZ adsorption was minimized in the potential range above a certain threshold and, in the surface potential range below the threshold, decreasing the surface potential increased the amount of protein adsorbed. The threshold potential for LSZ adsorption was shifted toward a positive value with increasing pH and was lower for Ta and Zr than for the others. A divalent anion salt (K2SO4) as an electrolyte exhibited the adsorption of LSZ in the positive potential range while a monovalent salt (KCl) did not. A comprehensive consideration of the obtained results suggests that two modes of interactions, namely the electric force by an external electric field and electrostatic interactions with ionized surface hydroxyl groups, act on the LSZ molecules and determine the extent of suppression of LSZ adsorption. All these findings appear to support the view that a base metal surface can be controlled for the affinity to a protein by manipulating the surface electric potential as has been reported on some electrode materials.
On the local zeta functions and the b-functions of certain hyperplane arrangements
Budur, Nero; Yuzvinsky, Sergey
2010-01-01
Conjectures of J. Igusa for p-adic local zeta functions and of J. Denef and F. Loeser for topological local zeta functions assert that (the real part of) the poles of these local zeta functions are roots of the Bernstein-Sato polynomials (i.e. the b-functions). We prove these conjectures for certain hyperplane arrangements, including the case of reduced hyperplane arrangements in three-dimensional affine space.
Zeta function zeros, powers of primes, and quantum chaos.
Sakhr, Jamal; Bhaduri, Rajat K; van Zyl, Brandon P
2003-08-01
We present a numerical study of Riemann's formula for the oscillating part of the density of the primes and their integer powers. The formula consists of an infinite series of oscillatory terms, one for each zero of the zeta function on the critical line, and was derived by Riemann in his paper on primes, assuming the Riemann hypothesis. We show that high-resolution spectral lines can be generated by the truncated series at all integer powers of primes and demonstrate explicitly that the relative line intensities are correct. We then derive a Gaussian sum rule for Riemann's formula. This is used to analyze the numerical convergence of the truncated series. The connections to quantum chaos and semiclassical physics are discussed.
Hamiltonian for the Zeros of the Riemann Zeta Function.
Bender, Carl M; Brody, Dorje C; Müller, Markus P
2017-03-31
A Hamiltonian operator H[over ^] is constructed with the property that if the eigenfunctions obey a suitable boundary condition, then the associated eigenvalues correspond to the nontrivial zeros of the Riemann zeta function. The classical limit of H[over ^] is 2xp, which is consistent with the Berry-Keating conjecture. While H[over ^] is not Hermitian in the conventional sense, iH[over ^] is PT symmetric with a broken PT symmetry, thus allowing for the possibility that all eigenvalues of H[over ^] are real. A heuristic analysis is presented for the construction of the metric operator to define an inner-product space, on which the Hamiltonian is Hermitian. If the analysis presented here can be made rigorous to show that H[over ^] is manifestly self-adjoint, then this implies that the Riemann hypothesis holds true.
Central Binomial Sums, Multiple Clausen Values and Zeta Values
Borwein, J M; Kamnitzer, J
2000-01-01
We find and prove relationships between Riemann zeta values and central binomial sums. We also investigate alternating binomial sums (also called Ap\\'ery sums). The study of non-alternating sums leads to an investigation of different types of sums which we call multiple Clausen values. The study of alternating sums leads to a tower of experimental results involving polylogarithms in the golden ratio. In the non-alternating case, there is a strong connection to polylogarithms of the sixth root of unity, encountered in the 3-loop Feynman diagrams of {\\tt hep-th/9803091} and subsequently in hep-ph/9910223, hep-ph/9910224, cond-mat/9911452 and hep-th/0004010.
Where do the tedious products of zetas come from?
Broadhurst, D J
2003-01-01
Lamentably, the full analytical content of the epsilon-expansion of the master two-loop two-point function, with arbitrary self-energy insertions in 4-2epsilon dimensions, is still unknown. Here we show that multiple zeta values (MZVs) of weights up to 12 suffice through O(epsilon^9). Products of primitive MZVs are generated by a processes of "pseudo-exponentiation"" whose combinatorics faithfully accord with expectations based on Kreimer's modified shuffle product and on the Drinfeld-Deligne conjecture. The existence of such a mechanism, relating thousands of complicated rational numbers, enables us to identify precise and simple combinations of MZVs specific to quantum field theories in even numbers of spacetime dimensions.
Briquet, M; Petit, P; Leroy, B; de Batz, B
2016-01-01
Aims. The main-sequence B-type star $\\zeta$ Cassiopeiae is known as a N-rich star with a magnetic field discovered with the Musicos spectropolarimeter. We model the magnetic field of the star by means of 82 new spectropolarimetric observations of higher precision to investigate the field strength, topology, and effect. Methods. We gathered data with the Narval spectropolarimeter installed at T\\'elescope Bernard Lyot (TBL, Pic du Midi, France) and applied the least-squares deconvolution technique to measure the circular polarisation of the light emitted from $\\zeta$ Cas. We used a dipole oblique rotator model to determine the field configuration by fitting the longitudinal field measurements and by synthesizing the measured Stokes V profiles. We also made use of the Zeeman-Doppler Imaging technique to map the stellar surface and to deduce the difference in rotation rate between the pole and equator. Results. $\\zeta$ Cas exhibits a polar field strength $B_{\\rm pol}$ of 100-150 G, which is the weakest polar fiel...
Surface chemistry dependent immunostimulative potential of porous silicon nanoplatforms.
Shahbazi, Mohammad-Ali; Fernández, Tahia D; Mäkilä, Ermei M; Le Guével, Xavier; Mayorga, Cristobalina; Kaasalainen, Martti H; Salonen, Jarno J; Hirvonen, Jouni T; Santos, Hélder A
2014-11-01
Nanoparticles (NPs) have been suggested for immunotherapy applications in order to optimize the delivery of immuno-stimulative or -suppressive molecules. However, low attention towards the impact of the NPs' physicochemical properties has presented a major hurdle for developing efficient immunotherapeutic agents. Here, the effects of porous silicon (PSi) NPs with different surface chemistries were evaluated on human monocyte-derived dendritic cells (MDDCs) and lymphocytes in order to highlight the importance of the NPs selection in immuno-stimulative or -suppressive treatment. Although all the PSi NPs showed high biocompatibility, only thermally oxidized PSi (TOPSi) and thermally hydrocarbonized PSi (THCPSi) NPs were able to induce very high rate of immunoactivation by enhancing the expression of surface co-stimulatory markers of the MDDCs (CD80, CD83, CD86, and HLA-DR), inducing T-cell proliferation, and also the secretion of interleukins (IL-1β, IL-4, IL-6, IL-10, IL-12, IFN-γ, and TNF-α). These results indicated a balanced increase in the secretion of Th1, Th2, and Treg cytokines. Moreover, undecylenic acid functionalized THCPSi, as well as poly(methyl vinyl ether-alt-maleic acid) conjugated to (3-aminopropyl)triethoxysilane functionalized thermally carbonized PSi and polyethyleneimine conjugated undecylenic acid functionalized THCPSi NPs showed moderate immunoactivation due to the mild increase in the above-mentioned markers. By contrast, thermally carbonized PSi (TCPSi) and (3-aminopropyl)triethoxysilane functionalized TCPSi NPs did not induce any immunological responses, suggesting that their application could be in the delivery of immunosuppressive molecules. Overall, our findings suggest all the NPs containing more nitrogen or oxygen on the outermost backbone layer have lower immunostimulatory effect than NPs with higher C-H structures on the surface.
Surface thermophysical properties on the potentially hazardous asteroid (99942) Apophis
Yu, Liang-Liang; Ji, Jianghui; Ip, Wing-Huen
2017-07-01
We investigate the surface thermophysical properties (thermal emissivity, thermal inertia, roughness fraction and geometric albedo) of asteroid (99942) Apophis, using the currently available mid-infrared observations from CanariCam on Gran Telescopio CANARIAS and far-infrared data from PACS on Herschel, based on the Advanced Thermophysical Model. We show that the thermal emissivity of Apophis should be wavelength dependent from 8.70 μm to 160 μm, and the maximum emissivity may appear around 20 μm, similar to that of Vesta. Moreover, we further derive the thermal inertia, roughness fraction, geometric albedo and effective diameter of Apophis within a possible 1σ scale of Γ ={100}-52+100{{{Jm}}}{{-}2} {{{s}}}{{-}0.{{5}}} {{{K}}}{{-}1}, {f}{{r}}=0.78˜ 1.0, {p}{{v}}={0.286}-0.026+0.030 and {D}{{eff}}={378}-25+19{{m}}, and 3σ scale of Γ ={100}-100+240 {{{Jm}}}{{-}2} {{{s}}}{{-}0.{{5}}} {{{K}}}{{-}1}, {f}{{r}}=0.2˜ 1.0, {p}{{v}}={0.286}-0.029+0.039 and {D}{{eff}}={378}-29+27{{m}}. The derived low thermal inertia but high roughness fraction may imply that Apophis could have regolith on its surface, where stronger space weathering but weaker regolith migration has happened in comparison with asteroid Itokawa. Our results show that small-size asteroids could also have fine regolith on the surface, and further infer that Apophis may have been delivered from the Main Belt by the Yarkovsky effect.
Transport signatures of surface potentials on three-dimensional topological insulators
Roy, Sthitadhi; Das, Sourin
2016-02-01
The spin-momentum-locked nature of the robust surface states of three-dimensional topological insulators (3D TIs) makes them promising candidates for spintronics applications. Surface potentials which respect time-reversal symmetry can exist at the surface between a 3D TI and the trivial vacuum. These potentials can distort the spin texture of the surface states while retaining their gapless nature. In this work, the effect of all such surface potentials on the spin textures is studied. Since a tunnel magnetoresistance signal carries the information of the spin texture, it is proposed that spin-polarized tunneling of electrons to a 3D TI surface can be used to uniquely identify the surface potentials and quantitatively characterize them.
Greben, Kyrylo; Li, Pinggui; Mayer, Dirk; Offenhäusser, Andreas; Wördenweber, Roger
2015-05-14
A streaming current/potential method is optimized and used for the analysis of the variation of the surface potential upon chemical modifications of a complex interface consisting of different organic molecules and gold nanoparticles (AuNPs). The surfaces of Si/SiO2 substrates modified with 3-aminopropyltriethoxysilane (APTES), AuNPs, and 11-amino-1-undecanethiol (aminothiols) are analyzed via pH and time dependent ζ potential measurements that reveal the stability and modification of the surface and identify crucial parameters for each individual preparation step. For instance, surface activation and especially molecular adsorbate layers tend not to be stable in time, whereas the substrate and the AuNPs provide a stable surface potential as long as impurities are avoided. It is shown that the streaming potential/current technique represents an ideal tool to analyze and monitor the complex surfaces and their modification.
Feuerbacher, Sven; Sommerfeld, Thomas; Cederbaum, Lorenz S
2004-02-15
Whereas conical intersections between potential energy surfaces of bound states are well known, the interaction of short-lived states has been investigated only rarely. Here, we present several systematically constructed model Hamiltonians to study the topology of intersecting complex potential energy surfaces describing short-lived states: We find the general phenomenon of doubly intersecting complex energy surfaces, i.e., there are two points instead of one as in the case of bound states where the potential energy surfaces coalesce. In addition, seams of intersections of the respective real and imaginary parts of the potential energy surfaces emanate from these two points. Using the Sigma* and Pi* resonance states of the chloroethene anion as a practical example, we demonstrate that our complete linear model Hamiltonian is able to reproduce all phenomena found in explicitly calculated ab initio complex potential energy surfaces.
Estimates of global dew collection potential on artificial surfaces
Vuollekoski, H.; Vogt, M.; Sinclair, V. A.; Duplissy, J.; Järvinen, H.; Kyrö, E.-M.; Makkonen, R.; Petäjä, T.; Prisle, N. L.; Räisänen, P.; Sipilä, M.; Ylhäisi, J.; Kulmala, M.
2015-01-01
The global potential for collecting usable water from dew on an artificial collector sheet was investigated by utilizing 34 years of meteorological reanalysis data as input to a dew formation model. Continental dew formation was found to be frequent and common, but daily yields were mostly below 0.1 mm. Nevertheless, some water-stressed areas such as parts of the coastal regions of northern Africa and the Arabian Peninsula show potential for large-scale dew harvesting, as the yearly yield may reach up to 100 L m-2 for a commonly used polyethylene foil. Statistically significant trends were found in the data, indicating overall changes in dew yields of between ±10% over the investigated time period.
SPECTROSCOPIC PROBING OF POTENTIAL SURFACES IN REACTIVE COLLISIONS
Telle, H.
1985-01-01
For the investigation of unstable intermediates, ABC*, which constitute the "transition states" in some simple reactive collisions, spectroscopic methods are beginning to provide valuable results. In a (relatively) simple approach molecules are photodissociated, and the interaction potentials during the process of separation (half-collision) are mapped in either absorption or emission ; the method will be described exemplary for the photolysis of NaI, giving rise to emission from NaI≠*. For r...
Electrohydrodynamics of binary electrolytes driven by modulated surface potentials
DEFF Research Database (Denmark)
Mortensen, Asger; Olesen, Laurits Højgaard; Belmon, L.;
2005-01-01
problem and obtain analytic solutions in the bulk for the pressure and velocity fields of the electrolyte and for the electric potential. We find good agreement between the numerics of the full problem and the analytics of the linear theory. Our work provides the theoretical foundations of circuit models...... discussed in the literature. The nonequilibrium approach also reveals unexpected high-frequency dynamics not predicted by circuit models....
Negative plasma potential relative to electron-emitting surfaces.
Campanell, M D
2013-09-01
Most works on plasma-wall interaction predict that with strong electron emission, a nonmonotonic "space-charge-limited" (SCL) sheath forms where the plasma potential is positive relative to the wall. We show that a fundamentally different sheath structure is possible where the potential monotonically increases toward a positively charged wall that is shielded by a single layer of negative charge. No ion-accelerating presheath exists in the plasma and the ion wall flux is zero. An analytical solution of the "inverse sheath" regime is demonstrated for a general plasma-wall system where the plasma electrons and emitted electrons are Maxwellian with different temperatures. Implications of the inverse sheath effect are that (a) the plasma potential is negative, (b) ion sputtering vanishes, (c) no charge is lost at the wall, and (d) the electron energy flux is thermal. To test empirically what type of sheath structure forms under strong emission, a full plasma bounded by strongly emitting walls is simulated. It is found that inverse sheaths form at the walls and ions are confined in the plasma. This result differs from past particle-in-cell simulation studies of emission which contain an artificial "source sheath" that accelerates ions to the wall, leading to a SCL sheath at high emission intensity.
COWAN, MM; VANDERMEI, HC; ROUXHET, PG; BUSSCHER, HJ
1992-01-01
The surface properties of nine Streptococcus mitis and four Peptostreptococcus micros strains from the oral cavity were examined and compared with a large group of oral streptococci. Zeta potential and contact angle measurements were employed to determine physico-chemical cell surface properties. In
Energy Technology Data Exchange (ETDEWEB)
Hayes, E.F.; Siu, A.K.Q.; Chapman, F.M. Jr.; Matcha, R.L.
1976-09-01
A potential energy surface for the Ne--H/sub 2//sup +/ reaction has been obtained in the LCAO--MO--SCF approximation. Analysis of the surface indicates that the reaction Ne+H/sub 2//sup +/..-->..NeH/sup +/+H should proceed with an endoergicity of 12 kcal/mole, in agreement with the experimental results of Chupka and Russell. Several procedures for parameterizing a diatomics-in-molecules (DIM) representation of the NeH/sub 2//sup +/ surface are considered. The results show that an accurate representation of the SCF surface can be obtained from the DIM model using a minimum of diatomic and triatomic data. (AIP)
Intermolecular potential energy surface and thermophysical properties of ethylene oxide
Energy Technology Data Exchange (ETDEWEB)
Crusius, Johann-Philipp, E-mail: johann-philipp.crusius@uni-rostock.de; Hassel, Egon [Lehrstuhl für Technische Thermodynamik, Universität Rostock, 18059 Rostock (Germany); Hellmann, Robert; Bich, Eckard [Institut für Chemie, Universität Rostock, 18059 Rostock (Germany)
2014-10-28
A six-dimensional potential energy hypersurface (PES) for two interacting rigid ethylene oxide (C{sub 2}H{sub 4}O) molecules was determined from high-level quantum-chemical ab initio calculations. The counterpoise-corrected supermolecular approach at the MP2 and CCSD(T) levels of theory was utilized to determine interaction energies for 10178 configurations of two molecules. An analytical site-site potential function with 19 sites per ethylene oxide molecule was fitted to the interaction energies and fine tuned to agree with data for the second acoustic virial coefficient from accurate speed of sound measurements. The PES was validated by computing the second virial coefficient, shear viscosity, and thermal conductivity. The values of these properties are substantiated by the best experimental data as they tend to fall within the uncertainty intervals and also obey the experimental temperature functions, except for viscosity, where experimental data are insufficient. Due to the lack of reliable data, especially for the transport properties, our calculated values are currently the most accurate estimates for these properties of ethylene oxide.
Kaliakin, Danil S.; Zaari, Ryan R.; Varganov, Sergey A.
2015-01-01
Teaching fundamental physical chemistry concepts such as the potential energy surface, transition state, and reaction path is a challenging task. The traditionally used oversimplified 2D representation of potential and free energy surfaces makes this task even more difficult and often confuses students. We show how this 2D representation can be…
Surface study of mercury-cadmium-telluride
Energy Technology Data Exchange (ETDEWEB)
Lops, V.C.
1985-01-01
Single crystals of Hg/sub 1-x/Cd/sub x/Te were studied to determine how changes in the surface conditions affected electrical properties. Infrared detector grade material from Honeywell Radiation Center (x = 0.2, bandgap near 10 ..mu..m) was used to examine the effects of changes in the surface charge density on electrical I/f noise. The surface charge density, which was controlled by the pH of the aqueous solution was measured in a zeta meter that operated much like a Millikan oil-drop experiment. The electrophoresis zeta potential measurements on (HgCd)Te identified the active surface oxide as TeO/sub 2/ and also revealed information on the surface chemistry. An experimental fit yielded the dissociation constant of tellurous acid, which was the result of TeO/sub 2/ combining with H/sub 2/O. The dissociation of tellurous acid was responsible for the measured surface charge densities and the surface chemistry from pH = 1 to pH = 8. At pH = 1, the surface was H/sub 3/TeO/sub 2//sup +/. At pH = 1.5, the surface was H/sub 2/TeO/sub 3/ which gave the neutral point, PZZP (Point of Zero Zeta Potential). With the pH between 2 and 6, the surface was HTeO/sub 3//sup -/. As the pH was changed to 7 and greater, the surface was TeO/sub 3//sup -/. Electrical I/f noise in (HgCd)Te was found to be dominated by bulk and not surface effects at room temperature.
Analytical approximation of the InGaZnO thin-film transistors surface potential
Colalongo, Luigi
2016-10-01
Surface-potential-based mathematical models are among the most accurate and physically based compact models of thin-film transistors, and in turn of indium gallium zinc oxide TFTs, available today. However, the need of iterative computations of the surface potential limits their computational efficiency and diffusion in CAD applications. The existing closed-form approximations of the surface potential are based on regional approximations and empirical smoothing functions that could result not accurate enough in particular to model transconductances and transcapacitances. In this work we present an extremely accurate (in the range of nV) and computationally efficient non-iterative approximation of the surface potential that can serve as a basis for advanced surface-potential-based indium gallium zinc oxide TFTs models.
Potential effects of forest management on surface albedo
Otto, J.; Bréon, F.-M.; Schelhaas, M.-J.; Pinty, B.; Luyssaert, S.
2012-04-01
Currently 70% of the world's forests are managed and this figure is likely to rise due to population growth and increasing demand for wood based products. Forest management has been put forward by the Kyoto-Protocol as one of the key instruments in mitigating climate change. For temperate and boreal forests, the effects of forest management on the stand-level carbon balance are reasonably well understood, but the biophysical effects, for example through changes in the albedo, remain elusive. Following a modeling approach, we aim to quantify the variability in albedo that can be attributed to forest management through changes in canopy structure and density. The modelling approach chains three separate models: (1) a forest gap model to describe stand dynamics, (2) a Monte-Carlo model to estimate the probability density function of the optical path length of photons through the canopy and (3) a physically-based canopy transfer model to estimate the interaction between photons and leaves. The forest gap model provides, on a monthly time step the position, height, diameter, crown size and leaf area index of individual trees. The Monte-Carlo model computes from this the probability density function of the distance a photon travels through crown volumes to determine the direct light reaching the forest floor. This information is needed by the canopy transfer model to calculate the effective leaf area index - a quantity that allows it to correctly represent a 3D process with a 1D model. Outgoing radiation is calculated as the result of multiple processes involving the scattering due to the canopy layer and the forest floor. Finally, surface albedo is computed as the ratio between incident solar radiation and calculated outgoing radiation. The study used two time series representing thinning from below of a beech and a Scots pine forest. The results show a strong temporal evolution in albedo during stand establishment followed by a relatively stable albedo once the canopy
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
The density functional theory (DFT) provides us an effective way to calculate large cluster systems with moderate computational demands. We calculate potential energy surfaces (PES) with several different approaches of DFT. The PES in the ground electronic state are related to HCP's isomerization process. The calculated PES are compared with the “experimental” PES obtained by fitting from the experimental vibrational spectra and that given by the “accurate” quantum chemistry calculation with more expensive computations. The comparisons show that the potential surfaces calculated with DFT methods can reach the accuracy of less than 0.1 eV.
Zeta Function Expression of Spin Partition Functions on Thermal AdS3
Directory of Open Access Journals (Sweden)
Floyd L.Williams
2015-07-01
Full Text Available We find a Selberg zeta function expression of certain one-loop spin partition functions on three-dimensional thermal anti-de Sitter space. Of particular interest is the partition function of higher spin fermionic particles. We also set up, in the presence of spin, a Patterson-type formula involving the logarithmic derivative of zeta.
An elementary and real approach to values of the Riemann zeta function
Bagdasaryan, A. G.
2010-02-01
An elementary approach for computing the values at negative integers of the Riemann zeta function is presented. The approach is based on a new method for ordering the integers. We show that the values of the Riemann zeta function can be computed, without using the theory of analytic continuation and any knowledge of functions of complex variable.
Random matrix theory and discrete moments of the Riemann zeta function
Energy Technology Data Exchange (ETDEWEB)
Hughes, C P [Raymond and Beverly Sackler School of Mathematical Sciences, Tel Aviv University, Tel Aviv 69978 (Israel)
2003-03-28
We calculate the discrete moments of the characteristic polynomial of a random unitary matrix, evaluated a small distance away from an eigenangle. Such results allow us to make conjectures about similar moments for the Riemann zeta function, and provide a uniform approach to understanding moments of the zeta function and its derivative.
Energy Technology Data Exchange (ETDEWEB)
Bouhafs, Nezha; Lique, François, E-mail: francois.lique@univ-lehavre.fr [LOMC–UMR 6294, CNRS-Université du Havre, 25 rue Philippe Lebon, BP 1123, 76063 Le Havre (France)
2015-11-14
We present a new three-dimensional potential energy surface (PES) for the NH(X{sup 3}Σ{sup −})–Ne van der Waals system, which explicitly takes into account the NH vibrational motion. Ab initio calculations of the NH–Ne PES were carried out using the open-shell single- and double-excitation coupled cluster approach with non-iterative perturbational treatment of triple excitations [RCCSD(T)]. The augmented correlation-consistent quadruple zeta (aug-cc-pVQZ) basis set was employed. Mid-bond functions were also included in order to improve the accuracy in the van der Waals well. Using this new PES, we have studied the collisional excitation of NH(X{sup 3}Σ{sup −}) by Ne. Close-coupling calculations of the collisional excitation cross sections of the fine-structure levels of NH by Ne are performed for energies up to 3000 cm{sup −1}, which yield, after thermal average, rate coefficients up to 350 K. The propensity rules between fine-structure levels are reported, and it is found that F-conserving cross sections are larger than F-changing cross sections even if the propensity rules are not as strong as for the NH–He system. The calculated rate coefficients are compared with available experimental measurements at room temperature and a fairly good agreement is found between experimental and theoretical data, confirming the good quality of the scattering calculations and also the accuracy of the potential energy surface used in this work.
Multi-loop zeta function regularization and spectral cutoff in curved spacetime
Energy Technology Data Exchange (ETDEWEB)
Bilal, Adel, E-mail: adel.bilal@lpt.ens.fr [Centre National de la Recherche Scientifique, Laboratoire de Physique Théorique de l' École Normale Supérieure, 24 rue Lhomond, F-75231 Paris Cedex 05 (France); Ferrari, Frank, E-mail: frank.ferrari@ulb.ac.be [Service de Physique Théorique et Mathématique, Université Libre de Bruxelles and International Solvay Institutes, Campus de la Plaine, CP 231, B-1050 Bruxelles (Belgium)
2013-12-21
We emphasize the close relationship between zeta function methods and arbitrary spectral cutoff regularizations in curved spacetime. This yields, on the one hand, a physically sound and mathematically rigorous justification of the standard zeta function regularization at one loop and, on the other hand, a natural generalization of this method to higher loops. In particular, to any Feynman diagram is associated a generalized meromorphic zeta function. For the one-loop vacuum diagram, it is directly related to the usual spectral zeta function. To any loop order, the renormalized amplitudes can be read off from the pole structure of the generalized zeta functions. We focus on scalar field theories and illustrate the general formalism by explicit calculations at one-loop and two-loop orders, including a two-loop evaluation of the conformal anomaly.
Das, Siddhartha; Chakraborty, Suman
2010-07-06
In this article, we investigate the implications of ionic conductivity variations within the electrical double layer (EDL) on the streaming potential estimation in pressure-driven fluidic transport through narrow confinements. Unlike the traditional considerations, we do not affix the ionic conductivities apriori by employing preset values of dimensionless parameters (such as the Dukhin number) to estimate the streaming potential. Rather, utilizing the Gouy-Chapman-Grahame model for estimating the electric potential and charge density distribution within the Stern layer, we first quantify the Stern layer electrical conductivity as a function of the zeta potential and other pertinent parameters quantifying the interaction of the ionic species with the charged surface. Next, by invoking the Boltzmann model for cationic and anionic distribution within the diffuse layer, we obtain the diffuse layer electrical conductivity. On the basis of these two different conductivities pertaining to the two different portions of the EDL as well as the bulk conductivity, we define two separate Dukhin numbers that turn out to be functions of the dimensionless zeta potential and the channel height to Debye length ratio. We derive analytical expressions for the streaming potential as a function of the fundamental governing parameters, considering the above. The results reveal interesting and significant deviations between the streaming potential predictions from the present considerations against the corresponding predictions from the classical considerations in which electrochemically consistent estimates of variable EDL conductivity are not traditionally accounted for. In particular, it is revealed that the variations of streaming potential with zeta potential are primarily determined by the competing effects of EDL electromigration and ionic advection. Over low and high zeta potential regimes, the Stern layer and diffuse layer conductivities predominantly dictate the streaming
Accuracy of Low-level Surface in Hierarchical Construction of Potential Energy Surface
Institute of Scientific and Technical Information of China (English)
Chun-rui Wang; Dong H. Zhang
2012-01-01
The effects of low-level PES on the overall accuracy of the final surface constructed by using hierarchical construction were investigated with the constructions of a number of global surfaces for the H3 system at UHF (UMP2,DFT-B3LYP,UCCSD(T))/vtz,and UCCSD(T)/avqz levels of theory.The total reaction probabilities for the H+H2 reaction calculated on these surfaces revealed that the accuracy of UCCSD(T)/avqz surface is very close to the well-known BKMP2 surface,while the UCCSD(T)/vtz PES has a slightly higher barrier.In contrast,the low-level theories (UHF,UMP2,DFT-B3LYP) with vtz basis set can only provide a qualitative description of this simplest reaction despite the fact that they are widely used to study reactions in complex systems.On the other hand,although these theories are not accurate on describing the reaction,they can be used to provide the lowlevel PESs for hierarchical construction of the UCCSD(T)/avqz PES with the number of UCCSD(T)/avqz energies substantially reduced.
Intermediate- and High-Velocity Ionized Gas toward zeta Orionis
Welty, D E; Raymond, J C; Mallouris, C; York, D G
2002-01-01
We combine UV spectra obtained with the HST/GHRS echelle, IMAPS, and Copernicus to study the abundances and physical conditions in the predominantly ionized gas seen at high (-105 to -65 km/s) and intermediate velocities (-60 to -10 km/s) toward zeta Ori. We have high resolution (FWHM ~ 3.3-4.5 km/s) and/or high S/N spectra for at least two significant ions of C, N, Al, Si, S, and Fe -- enabling accurate estimates for both the total N(H II) and the elemental depletions. C, N, and S have essentially solar relative abundances; Al, Si, and Fe appear to be depleted by about 0.8, 0.3-0.4, and 0.95 dex, respectively. While various ion ratios would be consistent with collisional ionization equilibrium (CIE) for T ~ 25,000-80,000 K, the widths of individual high-velocity absorption components indicate that T ~ 9000 K -- so the gas is not in CIE. Analysis of the C II fine-structure excitation equilibrium yields estimated densities (n_e ~ n_H ~ 0.1-0.2 cm^{-3}), thermal pressures (2 n_H T ~ 2000-4000 cm^{-3}K), and thi...
Advances in random matrix theory, zeta functions, and sphere packing.
Hales, T C; Sarnak, P; Pugh, M C
2000-11-21
Over four hundred years ago, Sir Walter Raleigh asked his mathematical assistant to find formulas for the number of cannonballs in regularly stacked piles. These investigations aroused the curiosity of the astronomer Johannes Kepler and led to a problem that has gone centuries without a solution: why is the familiar cannonball stack the most efficient arrangement possible? Here we discuss the solution that Hales found in 1998. Almost every part of the 282-page proof relies on long computer verifications. Random matrix theory was developed by physicists to describe the spectra of complex nuclei. In particular, the statistical fluctuations of the eigenvalues ("the energy levels") follow certain universal laws based on symmetry types. We describe these and then discuss the remarkable appearance of these laws for zeros of the Riemann zeta function (which is the generating function for prime numbers and is the last special function from the last century that is not understood today.) Explaining this phenomenon is a central problem. These topics are distinct, so we present them separately with their own introductory remarks.
Standard Model with extra dimensions and its zeta function regularization
García-Jiménez, I; Martínez-Pascual, E; Nápoles-Cañedo, G I; Novales-Sánchez, H; Toscano, J J
2016-01-01
We start from a field theory governed by the extra-dimensional $ISO(1,3+n)$ Poincar\\'e group and by the extended SM gauge group, $G({\\cal M}^{4+n})$. Then we construct an effective field theory whose symmetry groups are $ISO(1,3)$ and $G({\\cal M}^{4})$. The transition is carried out via two canonical transformations: a map that preserves, but it hides, the $SO(1,3+n)$ symmetry; and a transformation, given by Fourier series, that explicitly breaks $ISO(1,3+n)$ into $ISO(1,3)$, but conserves and hides the gauge symmetry $G({\\cal M}^{4+n})$, which manifests through nonstandard gauge transformations. From the 4-dimensional perspective, a particle that propagates in compact extra dimensions unfolds into a family of fields that reduces to the SM field if the size of the compact manifold is negligible. We include a full catalogue of Lagrangian terms that can be used to derive Feynman rules. The divergent character of the theory at one-loop is studied. A regularization scheme, based on the Epstein zeta function (EZF)...
DNA polymerase zeta (polζ) in higher eukaryotes
Institute of Scientific and Technical Information of China (English)
Gregory N Gan; John P Wittschieben; Birgitte φ Wittschieben; Richard D Wood
2008-01-01
Most current knowledge about DNA polymerase zeta (pol ζ) comes from studies of the enzyme in the budding yeast Saccharomyces cerevisiae, where polζ consists of a complex of the catalytic subunit Rev3 with Rev7, which associates with Rev1. Most spontaneous and induced mutagenesis in yeast is dependent on these gene products, and yeast pol can mediate translesion DNA synthesis past some adducts in DNA templates. Study of the homologous gene products in higher eukaryotes is in a relatively early stage, but additional functions for the eukaryotic proteins are already appar-ent. Suppression of vertebrate REV3L function not only reduces induced point mutagenesis but also causes larger-scale genuine instability by raising the frequency of spontaneous chromosome translocations. Disruption of Rev3L function is tolerated in Drosophila, Arabidopsis, and in vertebrate cell lines under some conditions, but is incompatible with mouse embryonic development. Functions for REV3L and REV7(MAD2B) in higher eukaryotes have been suggested not only in translesion DNA synthesis but also in some forms of homologous recombination, repair ofinterstrand DNA erosslinks, somatic hypermutation of immunoglobulin genes and cell-cycle control. This review discusses recent devel-opments in these areas.
A three-dimensional He-CO potential energy surface with improved long-range behavior
McBane, George C.
2016-12-01
A weakness of the ;CBS + corr; He-CO potential energy surface (Peterson and McBane, 2005) has been rectified by constraining the potential to adopt accurate long-range behavior for He-CO distances well beyond 15a0 . The resulting surface is very similar to the original in the main part of the interaction. Comparison with accurately known bound-state energies indicates that the surface is slightly improved in the region sampled by the highest lying bound states. The positions of shape and Feshbach resonances within a few cm-1 of the j = 1 excitation threshold are essentially unchanged. The low-energy scattering lengths changed noticeably. The revised surface generates a small negative limiting scattering length for collisions with 4He, while the original surface gave a small positive one. Both surfaces yield scattering lengths quite different from the widely used surface of Heijmen et al. (1997) for both He isotopes.
Kwon, Kideok D.; Newton, Aric G.
2016-10-01
The surfaces of clay minerals, which are abundant in atmospheric mineral dust, serve as an important medium to catalyze ice nucleation. The lateral edge surface of 2:1 clay minerals is postulated to be a potential site for ice nucleation. However, experimental investigations of the edge surface structure itself have been limited compared to the basal planes of clay minerals. Density functional theory (DFT) computational studies have provided insights into the pyrophyllite edge surface. Pyrophyllite is an ideal surrogate mineral for the edge surfaces of 2:1 clay minerals as it possesses no or little structural charge. Of the two most-common hydrated edge surfaces, the AC edge, (1 1 0) surface in the monoclinic polytype notation, is predicted to be more stable than the B edge, (0 1 0) surface. These stabilities, however, were determined based on the total energies calculated at 0 K and did not consider environmental effects such as temperature and humidity. In this study, atomistic thermodynamics based on periodic DFT electronic calculations was applied to examine the effects of environmental variables on the structure and thermodynamic stability of the common edge surfaces in equilibrium with bulk pyrophyllite and water vapor. We demonstrate that the temperature-dependent vibrational energy of sorbed water molecules at the edge surface is a significant component of the surface free energy and cannot be neglected when determining the surface stability of pyrophyllite. The surface free energies were calculated as a function of temperature from 240 to 600 K and water chemical potential corresponding to conditions from ultrahigh vacuum to the saturation vapor pressure of water. We show that at lower water chemical potentials (dry conditions), the AC and B edge surfaces possessed similar stabilities; at higher chemical potentials (humid conditions) the AC edge surface was more stable than the B edge surface. At high temperatures, both surfaces showed similar stabilities
Surface Potential of Dust Grains at the Sheath Edge of Electronegative Dusty Plasmas
Institute of Scientific and Technical Information of China (English)
段萍; 王正汹; 王文春; 刘金远; 刘悦; 王晓钢
2004-01-01
In this paper we investigate the dust surface potential at the sheath edge of electronegative dusty plasmas theoretically, using the standard fluid model for the sheath and treating electrons and negative ions as Boltzmann particles but positive ions and dust grains as cold fluids.The dust charging model is self-consistently coupled with the sheath formation criterion by the dust surface potential and the ion Mach number, moreover the dust density variation is taken into account. The numerical results reveal that the dust number density and negative ion number density as well as its temperature can significantly affect the dust surface potential at the sheath edge.
Greve, P.A.; Freudenthal, J.; Wit, S.L.
1972-01-01
Several analytical methods were employed to determine the concentrations of cholinesterase inhibitors in several Dutch surface waters. An Auto-Analyzer method was used for screening purposes; thin-layer chromatography and gas-liquid chromatography-mass spectrometry were used for identification and q
Quantum-mechanical tunneling differential operators, zeta-functions and determinants
Casahorrán, J
2002-01-01
We consider in detail the quantum-mechanical problem associated with the motion of a one-dimensional particle under the action of the double-well potential. Our main tool will be the euclidean (imaginary time) version of the path-integral method. Once we perform the Wick rotation, the euclidean equation of motion is the same as the usual one for the point particle in real time, except that the potential at issue is turned upside down. In doing so, our double-well potential becomes a two-humped potential. As required by the semiclassical approximation we may study the quadratic fluctuations over the instanton which represents in this context the localised finite-action solutions of the euclidean equation of motion. The determinants of the quadratic differential operators are evaluated by means of the zeta-function method. We write in closed form the eigenfunctions as well as the energy eigenvalues corresponding to such operators by using the shape-invariance symmetry. The effect of the multi-instantons configu...
Hot electron mediated desorption rates calculated from excited state potential energy surfaces
Olsen, Thomas; Schiøtz, Jakob
2008-01-01
We present a model for Desorption Induce by (Multiple) Electronic Transitions (DIET/DIMET) based on potential energy surfaces calculated with the Delta Self-Consistent Field extension of Density Functional Theory. We calculate potential energy surfaces of CO and NO molecules adsorbed on various transition metal surfaces, and show that classical nuclear dynamics does not suffice for propagation in the excited state. We present a simple Hamiltonian describing the system, with parameters obtained from the excited state potential energy surface, and show that this model can describe desorption dynamics in both the DIET and DIMET regime, and reproduce the power law behavior observed experimentally. We observe that the internal stretch degree of freedom in the molecules is crucial for the energy transfer between the hot electrons and the molecule when the coupling to the surface is strong.
Mixed Potential Energy Surfaces of the Ultrafast Isomerization of Retinal in Bacteriorhodopsin
Directory of Open Access Journals (Sweden)
Prokhorenko Valentyn I.
2013-03-01
Full Text Available We observe, using electronic two-dimensional photon echo spectroscopy, that the cis and trans potential energy surfaces of the ultrafast isomerization of retinal in bacteriorhodopsin are mixed via the hydrogen out of plane (HOOP mode.
Quantum Nuclear Extension of Electron Nuclear Dynamics on Folded Effective-Potential Surfaces
DEFF Research Database (Denmark)
Hall, B.; Deumens, E.; Ohrn, Y.;
2014-01-01
A perennial problem in quantum scattering calculations is accurate theoretical treatment of low energy collisions. We propose a method of extracting a folded, nonadiabatic, effective potential energy surface from electron nuclear dynamics (END) trajectories; we then perform nuclear wave packet...
Hydrophobic and electrostatic cell surface properties of Cryptosporidium parvum.
Drozd, C; Schwartzbrod, J
1996-04-01
Microbial adhesion to hydrocarbons and microelectrophoresis were investigated in order to characterize the surface properties of Cryptosporidium parvum. Oocysts exhibited low removal rates by octane (only 20% on average), suggesting that the Cryptosporidium sp. does not demonstrate marked hydrophobic properties. A zeta potential close to -25 mV at pH 6 to 6.5 in deionized water was observed for the parasite. Measurements of hydrophobicity and zeta potential were performed as a function of pH and ionic strength or conductivity. Hydrophobicity maxima were observed at extreme pH values, with 40% of adhesion of oocysts to octane. It also appeared that ionic strength (estimated by conductivity) could influence the hydrophobic properties of oocysts. Cryptosporidium oocysts showed a pH-dependent surface charge, with zeta potentials becoming less negative as pH was reduced, starting at -35 mV for alkaline pH and reaching 0 at isoelectric points for pH 2.5. On the other hand, variation of surface charge with respect to conductivity of the suspension tested in this work was quite small. The knowledge of hydrophobic properties and surface charge of the parasite provides information useful in, for example, the choice of various flocculation treatments, membrane filters, and cleaning agents in connection with oocyst recovery.
On the minima and convexity of Epstein zeta function
Lim, S. C.; Teo, L. P.
2008-07-01
Let Zn(s ;a1,…,an) be the Epstein zeta function defined as the meromorphic continuation of the function ∑k εZn{0}(∑i =1n[aiki]2)-s, Re s>n/2 to the complex plane. We show that for fixed s ≠n/2, the function Zn(s ;a1,…,an) as a function of (a1,…,an)ε(R+)n with fixed ∏i =1nai has a unique minimum at the point a1=⋯=an. When ∑i =1nci is fixed, the function (c1,…,cn)↦Zn(s ;ec1,…,ecn) can be shown to be a convex function of any (n -1) of the variables {c1,…,cn}. These results are then applied to the study of the sign of Zn(s ;a1,…,an) when s is in the critical range (0,n/2). It is shown that when 1≤n≤9, Zn(s ;a1,…,an) as a function of (a1,…,an)ε(R+)n can be both positive and negative for every s ε(0,n/2). When n ≥10, there are some open subsets In,+ of s ε(0,n/2), where Zn(s ;a1,…,an) is positive for all (a1,…,an)ε(R+)n. By regarding Zn(s ;a1,…,an) as a function of s, we find that when n ≥10, the generalized Riemann hypothesis is false for all (a1,…,an).
Borwein, J M
1998-01-01
We identify 998 closed hyperbolic 3-manifolds whose volumes are rationally related to Dedekind zeta values, with coprime integers $a$ and $b$ giving $a/b vol(M)=(-D)^{3/2}/(2\\pi)^{2n-4} (\\zeta_K(2))/(2\\zeta(2))$ for a manifold M whose invariant trace field $K$ has a single complex place, discriminant $D$, degree $n$, and Dedekind zeta value $\\zeta_K(2)$. The largest numerator of the 998 invariants of Hodgson-Weeks manifolds is, astoundingly, $a=2^4\\times23\\times37\\times691 =9,408,656$; the largest denominator is merely b=9. We also study the rational invariant a/b for single-complex-place cusped manifolds, complementary to knots and links, both within and beyond the Hildebrand-Weeks census. Within the censi, we identify 152 distinct Dedekind zetas rationally related to volumes. Moreover, 91 census manifolds have volumes reducible to pairs of these zeta values. Motivated by studies of Feynman diagrams, we find a 10-component 24-crossing link in the case n=2 and D=-20. It is one of 5 alternating platonic links,...
Ion-step method for surface potential sensing of silicon nanowires
Chen, Songyue; Nieuwkasteele, van Jan W.; Berg, van den Albert; Eijkel, Jan C.T.
2016-01-01
This paper presents a novel stimulus-response method for surface potential sensing of silicon nanowire (Si NW) field-effect transistors. When an "ion-step" from low to high ionic strength is given as a stimulus to the gate oxide surface, an increase of double layer capacitance is therefore expected.
Matsumura, H.; Kawasaki, K.; Okumura, N.; Kambara, M.; Norde, W.
2003-01-01
In this study we have elucidated the water-wettability and the electrokinetic surface potential of protein-covered dental materials. The proteins used here as typical proteins were human serum albumin and lysozyme from hen*s egg. The wettability (hydrophobicity/hydrophilicity) and the surface potent
Matsumura, H; Kawasaki, K; Okumura, N; Kambara, M; Norde, W
2003-01-01
In this study we have elucidated the water-wettability and the electrokinetic surface potential of protein-covered dental materials. The proteins used here as typical proteins were human serum albumin and lysozyme from hen's egg. The wettability (hydrophobicity/hydrophilicity) and the surface potent
The sand extraction potential of embedded land surface lowering in the Netherlands
Meulen, M.J. van der; Kleine, M.P.E. de; Veldkamp, J.G.; Dubelaar, C.W.; Pietersen, H.S.
2004-01-01
In the Netherlands, mineral extraction by means of dredging or quarrying meets with considerable societal resistance. Land surface lowering prior to large land reconstruction projects may raise fewer objections. We have calculated the potential yields of sand and gravel from land surface lowering
The sand extraction potential of embedded land surface lowering in the Netherlands
Van der Meulen, M.J.; De Kleine, M.P.E.; Veldkamp, J.G.; Dubbelaar, C.W.; Pietersen, H.S.
2004-01-01
In the Netherlands, mineral extraction by means of dredging or quarrying meets with considerable societal resistance. Land surface lowering prior to large land reconstruction projects may raise fewer objections. We have calculated the potential yields of sand and gravel form land surface lowering
Lettington, Matthew C
2012-01-01
We study the interplay between recurrences for zeta related functions at integer values, `Minor Corner Lattice' Toeplitz determinants and integer composition based sums. Our investigations touch on functional identities due to Ramanujan and Grosswald, the transcendence of the zeta function at odd integer values, the Li Criterion for the Riemann Hypothesis and pseudo-characteristic polynomials for zeta related functions. We begin with a result of Lettington's and some seemingly new Bernoulli relations, which we use to obtain a generalised Ramanujan polynomial and properties thereof.
Impact of Porosity and Electrolyte Composition on the Surface Charge of Hydroxyapatite Biomaterials.
Espanol, Montserrat; Mestres, Gemma; Luxbacher, Thomas; Dory, Jean-Baptiste; Ginebra, Maria-Pau
2016-01-13
The success or failure of a material when implanted in the body is greatly determined by the surface properties of the material and the host tissue reactions. The very first event that takes place after implantation is the interaction of soluble ions, molecules and proteins from the biological environment with the material surface leading to the formation of an adsorbed protein layer that will later influence cell attachment. In this context, the particular topography and surface charge of a material become critical as they influence the nature of the proteins that will adsorb. However, very limited information is available on the surface charge of porous substrates. Only until very recently was the determination of the zeta potential on porous membranes accurately determined. The goal of this work was to implement the previous findings for the determination of the zeta potential of a series of porous hydroxyapatite (HA) substrates and to assess how porosity affects the measurements. In addition, studies using various electrolytes were also performed to prove how the specific affinity of certain ions for HA can further impact surface charge. The results showed that all materials exhibited very similar external surface charge (approximately -23 mV), consistent with their almost identical topographies. However, the presence of interconnected pores underneath the sample surface resulted in an additional internal zeta potential that varied with the porosity content. Measurements with different electrolytes confirmed the selectivity of divalent ions for HA underlying the importance of testing biomaterials using relevant electrolytes.
Lysozyme adsorption on the colloidal chromium(III) oxide surface: Its impact on the system stability
Energy Technology Data Exchange (ETDEWEB)
Szewczuk-Karpisz, Katarzyna, E-mail: k.szewczuk-karpisz@wp.pl; Wiśniewska, Małgorzata; Myśliwiec, Dawid
2015-08-30
Highlights: • Lysozyme adsorption mechanism on the chromium(III) oxide surface was determined. • Surface charge density as well as zeta potential of Cr{sub 2}O{sub 3} particles were measured. • Turbidimetric method was used to estimate the suspension stability. • Depending on the pH value, lysozyme increases or decreases the system stability. - Abstract: This paper describes the lysozyme (LSZ) presence effect on the chromium(III) oxide (Cr{sub 2}O{sub 3}) suspension stability. First, the electrokinetic properties of the examined system, i.e. surface charge density and zeta potential of solid particles in the absence and presence of LSZ, were determined. The lysozyme addition reduces the metal oxide surface charge, which may be related to the interaction of the LSZ protonated amino groups with the adsorbent surface moieties. The LSZ macromolecules undergo adsorption on the Cr{sub 2}O{sub 3} surface only under electrostatic attraction. At the LSZ concentrations above 50 ppm the macromolecules cover completely the particle surface, which is evidenced by the observed zeta potential values. The LSZ influence on the Cr{sub 2}O{sub 3} suspension stability depends on the solution pH value. At pH 3, 4.6 and 7.6, the LSZ addition improves the system stability. In turn, at pH 9 it is associated with the slight suspension destabilization.
Moser, Jan
2017-01-01
In this paper we introduce new class of multiplicative interactions of the $\\zeta$-oscillating systems generated by a subset of power functions. The main result obtained expresses an analogue of prime decomposition (without the property of uniqueness). Dedicated to recalling of Nicola Tesla's oscillators
Local Surface Potential of GaN Nanostructures Probed by Kelvin Force Microscopy
Institute of Scientific and Technical Information of China (English)
GU Xiao-Xiao(顾骁骁); HUANG Da-Ming(黄大鸣); MORKOC Hadis
2003-01-01
We have measured the fluctuation in local surface potential of GaN epitaxial films having two different types of nanostructure, as-grown islands or, etched pits, by Kelvin probe force microscopy. We found that the perimeters of as-grown islands and the internal walls of, etched pits have lower surface potential as compared with the asgrown c-plane. The results show that the crystallographic facets tilted with respect to c-plane have higher work function and are electrically more active than c-surface.
DEFF Research Database (Denmark)
Gavnholt, Jeppe; Olsen, Thomas; Engelund, Mads;
2008-01-01
We present a modification of the Delta self-consistent field (Delta SCF) method of calculating energies of excited states in order to make it applicable to resonance calculations of molecules adsorbed on metal surfaces, where the molecular orbitals are highly hybridized. The Delta SCF approximation...... is a density-functional method closely resembling standard density-functional theory (DFT), the only difference being that in Delta SCF one or more electrons are placed in higher lying Kohn-Sham orbitals instead of placing all electrons in the lowest possible orbitals as one does when calculating the ground......-state energy within standard DFT. We extend the Delta SCF method by allowing excited electrons to occupy orbitals which are linear combinations of Kohn-Sham orbitals. With this extra freedom it is possible to place charge locally on adsorbed molecules in the calculations, such that resonance energies can...
Aguedo, Mario; Waché, Y.; Belin, J.-M.; Teixeira, J. A
2005-01-01
The surface of the lipid-degrading yeast, Yarrowia lipolytica, was characterized by contact angle and zeta potential (ζ) measurements. The cells were mainly hydrophilic with a negative charge that was only affected from pH 2 to 4. To study the effects of the surface charges on the biotransformation of methyl ricinoleate into the aroma compound, γ-decalactone, the ζ values of the substrate droplets were modified by adding a cationic surfactant into the medium at concentrations that...
Accelerating the search for global minima on potential energy surfaces using machine learning
Carr, S. F.; Garnett, R.; Lo, C. S.
2016-10-01
Controlling molecule-surface interactions is key for chemical applications ranging from catalysis to gas sensing. We present a framework for accelerating the search for the global minimum on potential surfaces, corresponding to stable adsorbate-surface structures. We present a technique using Bayesian inference that enables us to predict converged density functional theory potential energies with fewer self-consistent field iterations. We then discuss how this technique fits in with the Bayesian Active Site Calculator, which applies Bayesian optimization to the problem. We demonstrate the performance of our framework using a hematite (Fe2O3) surface and present the adsorption sites found by our global optimization method for various simple hydrocarbons on the rutile TiO2 (110) surface.
Mapping of electrical potentials from the chest surface - preprocessing and visualization
Directory of Open Access Journals (Sweden)
Vaclav Chudacek
2005-01-01
Full Text Available The aim of the paper is to present current research activity in the area of computer supported ECG processing. Analysis of heart electric field based on standard 12lead system is at present the most frequently used method of heart diseasediagnostics. However body surface potential mapping (BSPM that measures electric potentials from several tens to hundreds of electrodes placed on thorax surface has in certain cases higher diagnostic value given by data collection in areas that are inaccessible for standard 12lead ECG. For preprocessing, wavelet transform is used; it allows detect significant values on the ECG signal. Several types of maps, namely immediate potential, integral, isochronous, and differential.
Biofilm formation by Listeria monocytogenes on stainless steel surface and biotransfer potential
Directory of Open Access Journals (Sweden)
Maíra Maciel Mattos de Oliveira
2010-03-01
Full Text Available An experimental model was proposed to study biofilm formation by Listeria monocytogenes ATCC 19117 on AISI 304 (#4 stainless steel surface and biotransfer potential during this process. In this model, biofilm formation was conducted on the surface of stainless steel coupons, set on a stainless steel base with 4 divisions, each one supporting 21 coupons. Trypic Soy Broth was used as bacterial growth substrate, with incubation at 37 ºC and stirring of 50 rpm. The number of adhered cells was determined after 3, 48, 96, 144, 192 and 240 hours of biofilm formation and biotransfer potential from 96 hours. Stainless steel coupons were submitted to Scanning Electron Microscopy (SEM after 3, 144 and 240 hours. Based on the number of adhered cells and SEM, it was observed that L. monocytogenes adhered rapidly to the stainless steel surface, with mature biofilm being formed after 240 hours. The biotransfer potential of bacterium to substrate occurred at all the stages analyzed. The rapid capacity of adhesion to surface, combined with biotransfer potential throughout the biofilm formation stages, make L. monocytogenes a potential risk to the food industry. Both the experimental model developed and the methodology used were efficient in the study of biofilm formation by L. monocytogenes on stainless steel surface and biotransfer potential.
Institute of Scientific and Technical Information of China (English)
WANG Yu-Yu; ZHAO Yong-Tao; SUN Jian-Rong; LI De-Hui; QAYYUM Abdul; LI Jin-Yu; WANG Ping-Zhi; XIAO Guo-Qing
2011-01-01
Highly charged 129 Xeq+ (q =10-30) and 40Neq+ (q =4-8) ion-induced secondary electron emissions on the surface of highly oriented pyrolytic graphite (HOPG) are reported. The total secondary electron yield is measured as a function of the potential energy of incident ions. The experimental data are used to separate contributions of kinetic and potential electron yields. Our results show that about 4.5％ and 13.2％ of ion's potential energies are consumed in potential electron emission due to different Xeq+-HOPG and Neq+-HOPG combinations. A simple formula is introduced to estimate the fraction of ion's potential energy for potential electron emission.%@@ Highly charged 129 Xeq+(q =10-30) and 40Neq+(q =4-8) ion-induced secondary electron emissions on the surface of highly oriented pyrolytic graphite(HOPG) are reported.The total secondary electron yield is measured as a function of the potential energy of incident ions.The experimental data are used to separate contributions of kinetic and potential electron yields.Our results show that about 4.5% and 13.2% of ion's potential energies are consumed in potential electron emission due to different Xeq+-HOPG and Neq+-HOPG combinations.A simple formula is introduced to estimate the fraction of ion's potential energy for potential electron emission.
Analysis of Large Array Surface Myoelectric Potentials for the Low Back Muscles
2007-11-02
ANALYSIS OF LARGE ARRAY SURFACE MYOELECTRIC POTENTIALS FOR THE LOW BACK MUSCLES Steven I Reger, Ph.D. Vinod Sahgal M.D. Department of Physical...fewer subjects. The results indicated a potential of the model for clinical patient classification. Keywords - Myoelectric potential distribution, Low...computer science have improved signal processing, sensitivity and simultaneous multiple site data collection methods essential to the clinical
On the sign of the real part of the Riemann zeta-function
de Reyna, Juan Arias; van de Lune, Jan
2012-01-01
We consider the distribution of $\\arg\\zeta(\\sigma+it)$ on fixed lines $\\sigma > \\frac12$, and in particular the density \\[d(\\sigma) = \\lim_{T \\rightarrow +\\infty} \\frac{1}{2T} |\\{t \\in [-T,+T]: |\\arg\\zeta(\\sigma+it)| > \\pi/2\\}|\\,,\\] and the closely related density \\[d_{-}(\\sigma) = \\lim_{T \\rightarrow +\\infty} \\frac{1}{2T} |\\{t \\in [-T,+T]: \\Re\\zeta(\\sigma+it) < 0\\}|\\,.\\] Using classical results of Bohr and Jessen, we obtain an explicit expression for the characteristic function $\\psi_\\sigma(x)$ associated with $\\arg\\zeta(\\sigma+it)$. We give explicit expressions for $d(\\sigma)$ and $d_{-}(\\sigma)$ in terms of $\\psi_\\sigma(x)$. Finally, we give a practical algorithm for evaluating these expressions to obtain accurate numerical values of $d(\\sigma)$ and $d_{-}(\\sigma)$.
Random matrix theory and the zeros of {zeta}'(s)
Energy Technology Data Exchange (ETDEWEB)
Mezzadri, Francesco [School of Mathematics, University of Bristol, University Walk, Bristol, BS8 1TW, UK (United Kingdom)
2003-03-28
We study the density of the roots of the derivative of the characteristic polynomial Z(U, z) of an N x N random unitary matrix with distribution given by Haar measure on the unitary group. Based on previous random matrix theory models of the Riemann zeta function {zeta}(s), this is expected to be an accurate description for the horizontal distribution of the zeros of {zeta}'(s) to the right of the critical line. We show that as N {yields} {infinity} the fraction of the roots of Z'(U, z) that lie in the region 1 - x/(N - 1) {<=} vertical bar z vertical bar < 1 tends to a limit function. We derive asymptotic expressions for this function in the limits x {yields} {infinity} and x {yields} 0 and compare them with numerical experiments.
First detection of a magnetic field in the fast rotating runaway Oe star zeta Ophiuchi
Hubrig, S; Schoeller, M
2011-01-01
The star zeta Ophiuchi is one of the brightest massive stars in the northern hemisphere and was intensively studied in various wavelength domains. The currently available observational material suggests that certain observed phenomena are related to the presence of a magnetic field. We acquired spectropolarimetric observations of zeta Oph with FORS1 mounted on the 8-m Kueyen telescope of the VLT to investigate if a magnetic field is indeed present in this star. Using all available absorption lines, we detect a mean longitudinal magnetic field B_z_all = 141+-45G, confirming the magnetic nature of this star. We review the X-ray properties of zeta Oph with the aim to understand whether the X-ray emission of zeta Oph is dominated by magnetic or by wind instability processes.
Goutet, Philippe
2009-01-01
The aim of this article is to illustrate, on the example of Dwork hypersurfaces, how the study of the representation of a finite group of automorphisms of a hypersurface in its etale cohomology allows to factor its zeta function.
Seiberg duality, quiver gauge theories, and Ihara’s zeta function
Zhou, Da; Xiao, Yan; He, Yang-Hui
2015-07-01
We study Ihara’s zeta function for graphs in the context of quivers arising from gauge theories, especially under Seiberg duality transformations. The distribution of poles is studied as we proceed along the duality tree, in light of the weak and strong graph versions of the Riemann Hypothesis. As a by-product, we find a refined version of Ihara’s zeta function to be the generating function for the generic superpotential of the gauge theory.
VizieR Online Data Catalog: Chemical abundances of zeta Reticuly (Adibekyan+, 2016)
Adibekyan, V.; Delgado-Mena, E.; Figueira, P.; Sousa, S. G.; Santos, N. C.; Faria, J. P.; Gonzalez Hernandez, J. I.; Israelian, G.; Harutyunyan, G.; Suarez-Andres, L.; Hakobyan, A. A.
2016-05-01
The file table1.dat lists stellar parameters, S/N, and observation dates of zeta1 Ret and zeta2 Ret derived from individual and combined spectra The file ew.dat lists the equivalent widths (EW) of all the spectral lines. The file s_lines.dat lists the lines that were used in this study. The file abund.dat lists the derived abundances of the elements for each star and spectra. (4 data files).
Wei, Benxi; Xu, Xueming; Jin, Zhengyu; Tian, Yaoqi
2014-01-01
Surface chemical compositions of starch nanocrystals (SNC) prepared using sulfuric acid (H2SO4) and hydrochloric acid (HCl) hydrolysis were analyzed by X-ray photoelectron spectroscopy (XPS) and FT-IR. The results showed that carboxyl groups and sulfate esters were presented in SNC after hydrolysis with H2SO4, while no sulfate esters were detected in SNC during HCl-hydrolysis. TEM results showed that, compared to H2SO4-hydrolyzed sample, a wider size distribution of SNC prepared by HCl-hydrolysis were observed. Zeta-potentials were -23.1 and -5.02 mV for H2SO4- and HCl-hydrolyzed SNC suspensions at pH 6.5, respectively. Nevertheless, the zeta-potential values decreased to -32.3 and -10.2 mV as the dispersion pH was adjusted to 10.6. After placed 48 h at pH 10.6, zeta-potential increased to -24.1 mV for H2SO4-hydrolyzed SNC, while no change was detected for HCl-hydrolyzed one. The higher zeta-potential and relative small particle distribution of SNC caused more stable suspensions compared to HCl-hydrolyzed sample.
Directory of Open Access Journals (Sweden)
Benxi Wei
Full Text Available Surface chemical compositions of starch nanocrystals (SNC prepared using sulfuric acid (H2SO4 and hydrochloric acid (HCl hydrolysis were analyzed by X-ray photoelectron spectroscopy (XPS and FT-IR. The results showed that carboxyl groups and sulfate esters were presented in SNC after hydrolysis with H2SO4, while no sulfate esters were detected in SNC during HCl-hydrolysis. TEM results showed that, compared to H2SO4-hydrolyzed sample, a wider size distribution of SNC prepared by HCl-hydrolysis were observed. Zeta-potentials were -23.1 and -5.02 mV for H2SO4- and HCl-hydrolyzed SNC suspensions at pH 6.5, respectively. Nevertheless, the zeta-potential values decreased to -32.3 and -10.2 mV as the dispersion pH was adjusted to 10.6. After placed 48 h at pH 10.6, zeta-potential increased to -24.1 mV for H2SO4-hydrolyzed SNC, while no change was detected for HCl-hydrolyzed one. The higher zeta-potential and relative small particle distribution of SNC caused more stable suspensions compared to HCl-hydrolyzed sample.
The Effect of Chloride Ions on the Activity of Cerussite Surfaces
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Qicheng Feng
2016-09-01
Full Text Available Chloride ions were found to potentially increase activity of cerussite surfaces. Dissolution experiments, zeta potential measurements, X-ray photoelectron spectroscopy (XPS studies, and density functional theory (DFT computation were conducted in this study. Dissolution experiments showed that the lead ion concentrations in the NaCl solution system were lower than those in the deionized water system and that the lead ion concentrations in NaCl + Na2S aqueous systems decreased by approximately one order of magnitude compared with that in the Na2S system alone. Results of zeta potential measurements revealed that the pretreatment with chloride ions of cerussite caused a more positive zeta potential than that without chloride ions. XPS analysis results indicated that the number of lead ions on the mineral surface increased after cerussite was treated with chloride ions. Results of DFT computation implied that the number of lead atoms on the mineral surface increased and that the activity improved after PbCl+ was adsorbed onto the cerussite surface. The contribution of chloride ions to the activity on the mineral surface is attributed to the increase in the number of active sites and enhancement in the activity of these sites, resulting in improved sulfidization and flotation performance.
Characterizing the surface charge of synthetic nanomembranes by the streaming potential method
Datta, Subhra; Conlisk, A. T.; Kanani, Dharmesh M.; Zydney, Andrew L.; Fissell, William H.; Roy, Shuvo
2010-01-01
The inference of the surface charge of polyethylene glycol (PEG)-coated and uncoated silicon membranes with nanoscale pore sizes from streaming potential measurements in the presence of finite electric double layer (EDL) effects is studied theoretically and experimentally. The developed theoretical model for inferring the pore wall surface charge density from streaming potential measurements is applicable to arbitrary pore cross-sectional shapes and accounts for the effect of finite salt concentration on the ionic mobilities and the thickness of the deposited layer of PEG. Theoretical interpretation of the streaming potential data collected from silicon membranes having nanoscale pore sizes, with/without pore wall surface modification with PEG, indicates that finite electric double layer (EDL) effects in the pore-confined electrolyte significantly affect the interpretation of the membrane charge and that surface modification with PEG leads to a reduction in the pore wall surface charge density. The theoretical model is also used to study the relative significance of the following uniquely nanoscale factors affecting the interpretation of streaming potential in moderate to strongly charged pores: altered net charge convection by applied pressure differentials, surface-charge effects on ionic conduction, and electroosmotic convection of charges. PMID:20462592
Zodiatis, George; Galanis, George; Nikolaidis, Andreas; Stylianoy, Stavros; Liakatas, Aristotelis
2015-04-01
The use of wave energy as an alternative renewable is receiving attention the last years under the shadow of the economic crisis in Europe and in the light of the promising corresponding potential especially for countries with extended coastline. Monitoring and studying the corresponding resources is further supported by a number of critical advantages of wave energy compared to other renewable forms, like the reduced variability and the easier adaptation to the general grid, especially when is jointly approached with wind power. Within the framework, a number of countries worldwide have launched research and development projects and a significant number of corresponding studies have been presented the last decades. However, in most of them the impact of wave-sea surface currents interaction on the wave energy potential has not been taken into account neglecting in this way a factor of potential importance. The present work aims at filling this gap for a sea area with increased scientific and economic interest, the Eastern Mediterranean Sea. Based on a combination of high resolution numerical modeling approach with advanced statistical tools, a detailed analysis is proposed for the quantification of the impact of sea surface currents, which produced from downscaling the MyOcean-FO regional data, to wave energy potential. The results although spatially sensitive, as expected, prove beyond any doubt that the wave- sea surface currents interaction should be taken into account for similar resource analysis and site selection approaches since the percentage of impact to the available wave power may reach or even exceed 20% at selected areas.
The Effect of Images on Surface Potential and Resistance Calculation of Grounding Systems
Directory of Open Access Journals (Sweden)
MARTINS, A.
2015-05-01
Full Text Available In the grounding systems with a two layers soil, the calculation of the surface potential using the image method is sometimes impossible due to singularities, avoiding researchers to use the method for electrodes in the bottom layer. In the literature this problem solution is refereed as unreliable or solved with other more complex methods. This paper presents a new approach to calculate the surface potentials in a two. layer soil, for electrodes in the bottom layer, when images are at surface. The singularities in computing surface voltage, when the first image upwards lies at surface, are analysed and it's shown that a small change in top layer thickness allows an approximate solution. Surface potentials due to grid conductor are also considered and the values of resistance are compared with those from other methodologies. Singularities for a ground rod that crosses the two layers are also treated. The obtained values of resistance are not satisfactory, due to lower segments images that overlap the upper segments. This paper also proposes shifting the surface of the upper part of the ground rod, in the upper layer, or taking the modulus of the mutual resistance, to overcome this difficulty.
Ab initio intermolecular potential energy surface of He-LiH
Institute of Scientific and Technical Information of China (English)
鄢国森; 杨明晖; 谢代前
1997-01-01
The intermolecular potential energy surface of He-LiH complex was studied using the full-electronic complete forth-order Miller-Plesset perturbation (MPPT) method.In ab initio calculations,the bond length of LiH was fixed at 0 159 5 nm.The potential has two local minima of Vm=-179.93 cm for the linear He LiH geormetrv at Rm=0.227 nm and Vm=-10.44 cm-1 for the linear He-HL1 geometry at Rm=0.516 nm The potemal exhibits strong anisotropy The analytic potential function with 31 parameters was determined by fitting to the calculated ab,mtio potentials The influence of variation of LiH bond length on the potential energy surface was also studied
Directory of Open Access Journals (Sweden)
A. Loew
2008-01-01
Full Text Available Land surface models (LSM are widely used as scientific and operational tools to simulate mass and energy fluxes within the soil vegetation atmosphere continuum for numerous applications in meteorology, hydrology or for geobiochemistry studies. A reliable parameterization of these models is important to improve the simulation skills. Soil moisture is a key variable, linking the water and energy fluxes at the land surface. An appropriate parameterisation of soil hydraulic properties is crucial to obtain reliable simulation of soil water content from a LSM scheme. Parameter inversion techniques have been developed for that purpose to infer model parameters from soil moisture measurements at the local scale. On the other hand, remote sensing methods provide a unique opportunity to estimate surface soil moisture content at different spatial scales and with different temporal frequencies and accuracies. The present paper investigates the potential to use surface soil moisture information to infer soil hydraulic characteristics using uncertain observations. Different approaches to retrieve soil characteristics from surface soil moisture observations is evaluated and the impact on the accuracy of the model predictions is quantified. The results indicate that there is in general potential to improve land surface model parameterisations by assimilating surface soil moisture observations. However, a high accuracy in surface soil moisture estimates is required to obtain reliable estimates of soil characteristics.
Is the Isentropic Surface Always Impermeable to the Potential Vorticity Substance?
Institute of Scientific and Technical Information of China (English)
Chanh Q. KIEU; Da-Lin ZHANG
2012-01-01
The impermeability of isentropic surfaces by the potential vorticity substance (PVS) has often been used to help understand the generation of potential vorticity in the presence of diabatic heating and friction.In this study,we examined singularities of isentropic surfaces that may develop in the presence of diabatic heating and the fictitious movements of the isentropic surfaces that are involved in deriving the PVS impermeability theorem.Our results show that such singularities could occur in the upper troposphere as a result of intense convective-scale motion,at the cloud top due to radiative cooling,or within the well-mixed boundary layer.These locally ill-defined conditions allow PVS to penetrate across an isentropic surface.Wc conclude that the PVS impermeability theorem is generally valid for the stably stratified atmosphere in the absence of diabatic heating.
Modeling Solar-Wind Heavy-Ions' Potential Sputtering of Lunar KREEP Surface
Barghouty, A. F.; Meyer, F. W.; Harris, R. P.; Adams, J. H., Jr.
2012-01-01
Recent laboratory data suggest that potential sputtering may be an important weathering mechanism that can affect the composition of both the lunar surface and its tenuous exosphere; its role and implications, however, remain unclear. Using a relatively simple kinetic model, we will demonstrate that solar-wind heavy ions induced sputtering of KREEP surfaces is critical in establishing the timescale of the overall solar-wind sputtering process of the lunar surface. We will also also show that potential sputtering leads to a more pronounced and significant differentiation between depleted and enriched surface elements. We briefly discuss the impacts of enhanced sputtering on the composition of the regolith and the exosphere, as well as of solar-wind sputtering as a source of hydrogen and water on the moon.
Self-consistent density functional calculation of the image potential at a metal surface
Energy Technology Data Exchange (ETDEWEB)
Jung, J [Departamento de Fisica Fundamental, Universidad Nacional de Educacion a Distancia, Apartado 60141, 28080 Madrid (Spain); Alvarellos, J E [Departamento de Fisica Fundamental, Universidad Nacional de Educacion a Distancia, Apartado 60141, 28080 Madrid (Spain); Chacon, E [Instituto de Ciencias de Materiales de Madrid, Consejo Superior de Investigaciones CientIficas, E-28049 Madrid (Spain); GarcIa-Gonzalez, P [Departamento de Fisica Fundamental, Universidad Nacional de Educacion a Distancia, Apartado 60141, 28080 Madrid (Spain)
2007-07-04
It is well known that the exchange-correlation (XC) potential at a metal surface has an image-like asymptotic behaviour given by -1/4(z-z{sub 0}), where z is the coordinate perpendicular to the surface. Using a suitable fully non-local functional prescription, we evaluate self-consistently the XC potential with the correct image behaviour for simple jellium surfaces in the range of metallic densities. This allows a proper comparison between the corresponding image-plane position, z{sub 0}, and other related quantities such as the centroid of an induced charge by an external perturbation. As a by-product, we assess the routinely used local density approximation when evaluating electron density profiles, work functions, and surface energies by focusing on the XC effects included in the fully non-local description.
Rubiano, C A Rios; Mitnik, D M; Silkin, V M; Gravielle, M S
2016-01-01
The influence of the crystallographic orientation of a typical metal surface, like aluminum, on electron emission spectra produced by grazing incidence of ultrashort laser pulses is investigated by using the band-structure-based-Volkov (BSB-V) approximation. The present version of the BSB-V approach includes not only a realistic description of the surface interaction, accounting for band structure effects, but also effects due to the induced potential that originates from the collective response of valence-band electrons to the external electromagnetic field. The model is applied to evaluate differential electron emission probabilities from the valence band of Al(100) and Al(111). For both crystallographic orientations, the contribution of partially occupied surface electronic states and the influence of the induced potential are separately analyzed as a function of the laser carrier frequency. We found that the induced potential strongly affects photoelectron emission distributions, opening a window to scrut...
Energy Technology Data Exchange (ETDEWEB)
Winter, Matthias
2011-07-08
Image-potential resonances on the (100) surface of pure Aluminum are investigated experimentally and theoretically. The experiments are conducted both energy- and time-resolved using the method of two-photon photoemission spectroscopy. The main attention of the theoretical examination and extensive numerical calculations is devoted to the interaction between surface and bulk states. Image-potential resonances on Al(100) are a system in which a complete series of discrete Rydberg states strongly couples to a continuum of states. As a simple metal it also provides a good opportunity to test theoretical models of the structure of the potential at metal surfaces. This work represents the first high-resolution investigation of image-potential resonances with such strong resonance character. For the first time, it is demonstrated experimentally that isolated image-potential resonances exist on an Aluminum surface. On the (100) surface of Aluminum the second through fifth image-potential resonance are resolved and both, their energies and lifetimes are measured. The binding energies of the image-potential resonances form a Rydberg series of states {epsilon}{sub n}=-(0,85 eV)/((n+a){sup 2}). Within the accuracy of the measurement it is not necessary to introduce a quantum defect a (a=0.022{+-}0.035). Using angle-resolved two-photon photoemission spectroscopy the effective mass of electrons in the second image-potential resonance is measured to 1.01{+-}0.11 electron masses. The lifetimes of the resonances increase as {tau}{sub n} = (1.0{+-}0.2)fs.n{sup 3} starting from n=2. Calculations using the density matrix formalism show that the experimentally observed lifetimes can be explained well by electrons decaying into the bulk. The effect of resonance trapping leads to extended lifetimes in the process. Contrary to common theoretical models of image-potential states at metal surfaces the first image-potential resonance cannot be observed in two-photon photoemission on Al(100
Notter, Robert H; Wang, Zhongyi; Wang, Zhengdong; Davy, Jason A; Schwan, Adrian L
2007-01-01
The synthesis of three phosphoglycerols is described, one of which contains the previously unknown phosphonoglycerol headgroup. The surface tension-lowering capabilities of synthetic lung surfactant mixtures containing the PG analogs were measured on the pulsating bubble surfactometer and compared to known controls. The PG-containing mixtures exhibited superior surface tension-lowering properties indicating the significant potential of these analogs as components in synthetic exogenous lung surfactants.
A Study of Surface Motor Unit Action Potentials in First Dorsal Interosseus (FDI) Muscle
2007-11-02
Lefever and Carlo J. Deluca, "A Procedure for Decomposing the Myoelectric Signal Into It’s Constituent Action Potentials---Part 1, Technique, Theory, and...of surface MUAP’s using wavelet matching technique. II. SURFACE MUAP’S AND WAVELETS EMG signals are composed of different MUAP’s. Each...displays an impulse property, which means that it changes in a rapid fashion. Due to this property, the EMG signal is well suited to wavelet analysis
Effects of PV Module Soiling on Glass Surface Resistance and Potential-Induced Degradation
Energy Technology Data Exchange (ETDEWEB)
Hacke, Peter; Button, Patrick; Hendrickson, Alex; Spataru, Sergiu; Glick, Stephen
2015-06-14
The goals of the project were: Determine applicability of transmission line method (TLM) to evaluate sheet resistance of soils on module glass;
Evaluate various soils on glass for changes in surface resistance and their ability to promote potential-induced degradation with humidity (PID);
Evaluate PID characteristics, rate, and leakage current increases on full-size mc-Si modules associated with a conductive soil on the surface.
The impact of surface area, volume, curvature, and Lennard-Jones potential to solvation modeling.
Nguyen, Duc D; Wei, Guo-Wei
2017-01-05
This article explores the impact of surface area, volume, curvature, and Lennard-Jones (LJ) potential on solvation free energy predictions. Rigidity surfaces are utilized to generate robust analytical expressions for maximum, minimum, mean, and Gaussian curvatures of solvent-solute interfaces, and define a generalized Poisson-Boltzmann (GPB) equation with a smooth dielectric profile. Extensive correlation analysis is performed to examine the linear dependence of surface area, surface enclosed volume, maximum curvature, minimum curvature, mean curvature, and Gaussian curvature for solvation modeling. It is found that surface area and surfaces enclosed volumes are highly correlated to each other's, and poorly correlated to various curvatures for six test sets of molecules. Different curvatures are weakly correlated to each other for six test sets of molecules, but are strongly correlated to each other within each test set of molecules. Based on correlation analysis, we construct twenty six nontrivial nonpolar solvation models. Our numerical results reveal that the LJ potential plays a vital role in nonpolar solvation modeling, especially for molecules involving strong van der Waals interactions. It is found that curvatures are at least as important as surface area or surface enclosed volume in nonpolar solvation modeling. In conjugation with the GPB model, various curvature-based nonpolar solvation models are shown to offer some of the best solvation free energy predictions for a wide range of test sets. For example, root mean square errors from a model constituting surface area, volume, mean curvature, and LJ potential are less than 0.42 kcal/mol for all test sets. © 2016 Wiley Periodicals, Inc.
Institute of Scientific and Technical Information of China (English)
Zdeněk Frledl; Marcela Jungová; Svatopluk Zeman; Adéla Husarová
2011-01-01
The friction sensitivity (FS) of five aliphatic linear and eight cyclic nitramines has been determined and correlated with DFT B3LYP/6-31-G(d,p) // 6-311 + G(d,p) positive ( VS,max ) and negative ( VS,min ) extremes of molecular surface electrostatic potentials VS (r).While there is an ambiguous relationship between the VS.max values and FS values,the decrease of FS is connected ( more or less) with increase in VS,min values.
Khromenkova, E P; Dimidova, L L; Dumbadze, O S; Aidinov, G T; Shendo, G L; Agirov, A Kh; Batchaev, Kh Kh
2015-01-01
Sanitary and parasitological studies of the waste effluents and surface reservoir waters were conducted in the south of Russia. The efficiency of purification of waste effluents from the pathogens of parasitic diseases was investigated in the region's sewage-purification facilities. The water of the surface water reservoirs was found to contain helminthic eggs and larvae and intestinal protozoan cysts because of the poor purification and disinfection of service fecal sewage waters. The poor purification and disinvasion of waste effluents in the region determine the potential risk of contamination of the surface water reservoirs and infection of the population with the pathogens of human parasitic diseases.
Lee, Myoung-Jae; Jung, Young-Dae
2017-02-01
High frequency electrostatic wave propagation in a dense and semi-bounded electron quantum plasma is investigated with consideration of the Bohm potential. The dispersion relation for the surface mode of quantum plasma is derived and numerically analyzed. We found that the quantum effect enhances the frequency of the wave especially in the high wave number regime. However, the frequency of surface wave is found to be always lower than that of the bulk wave for the same quantum wave number. The group velocity of the surface wave for various quantum wave number is also obtained.
Visualization of GaN surface potential using terahertz emission enhanced by local defects
Sakai, Yuji; Kawayama, Iwao; Nakanishi, Hidetoshi; Tonouchi, Masayoshi
2015-09-01
Wide-gap semiconductors have received significant attention for their advantages over existing semiconductors in energy-efficient power devices. To realize stable and reliable wide-gap semiconductor devices, the basic physical properties, such as the electric properties on the surface and at the interface, should be revealed. Here, we report visualization of terahertz (THz) emission from the surface of GaN, which is excited by ultraviolet femtosecond laser pulses. We found that the THz emission is enhanced by defects related to yellow luminescence, and this phenomenon is explained through the modification of band structures in the surface depletion layer owing to trapped electrons at defect sites. Our results demonstrate that the surface potential in a GaN surface could be detected by laser-induced THz emission. Moreover, this method enables feasible evaluation of the distribution of non-radiative defects, which are undetectable with photoluminescence, and it contributes to the realization normally-off GaN devices.
Heytens, Elke; Schmitt-John, Thomas; Moser, Jakob M; Jensen, Nanna Mandøe; Soleimani, Reza; Young, Claire; Coward, Kevin; Parrington, John; De Sutter, Petra
2010-12-01
Failed fertilization after intracytoplasmic sperm injection (ICSI) can be due to a reduced oocyte-activation capacity caused by reduced concentrations and abnormal localization of the oocyte-activation factor phospholipase C (PLC) zeta. Patients with this condition can be helped to conceive by artificial activation of oocytes after ICSI with calcium ionophore (assisted oocyte activation; AOA). However some concern still exists about this approach. Mouse models could help to identify potential oocyte-activation strategies and evaluate their safety. In this study, the fertilizing capacity of wobbler sperm cells was tested and the efficiency of AOA with two exposures to ionomycin to restore fertilization and embryo development was studied. The quality of the obtained blastocysts was assessed and embryo transfer was performed to evaluate post-implantation development. The presence of PLCzeta in the spermatozoa and testis of the wobbler mouse was evaluated by PLCzeta immunostaining and quantitative reverse-transcription polymerase chain reaction. Sperm cells from wobbler mice had reduced fertilizing capacity and abnormalities in PLCzeta localization, but not in its expression. Artificially activating the oocytes restored fertilization and embryo development. Therefore, the wobbler mouse can be a model for failed fertilization after ICSI to study PLCzeta dynamics and aid in optimization of the AOA method.
Directory of Open Access Journals (Sweden)
Jena B. Hales
2015-01-01
Full Text Available Spatial memory in rodents can be erased following the infusion of zeta inhibitory peptide (ZIP into the dorsal hippocampus via indwelling guide cannulas. It is believed that ZIP impairs spatial memory by reversing established late-phase long-term potentiation (LTP. However, it is unclear whether other forms of hippocampus-dependent memory, such as recognition memory, are also supported by hippocampal LTP. In the current study, we tested recognition memory in rats following hippocampal ZIP infusion. In order to combat the limited targeting of infusions via cannula, we implemented a stereotaxic approach for infusing ZIP throughout the dorsal, intermediate, and ventral hippocampus. Rats infused with ZIP 3–7 days after training on the novel object recognition task exhibited impaired object recognition memory compared to control rats (those infused with aCSF. In contrast, rats infused with ZIP 1 month after training performed similar to control rats. The ability to form new memories after ZIP infusions remained intact. We suggest that enhanced recognition memory for recent events is supported by hippocampal LTP, which can be reversed by hippocampal ZIP infusion.
Fermi, Davide
2015-01-01
This is the first one of a series of papers about zeta regularization of the divergences appearing in the vacuum expectation value (VEV) of several local and global observables in quantum field theory. More precisely we consider a quantized, neutral scalar field on a domain in any spatial dimension, with arbitrary boundary conditions and, possibly, in presence of an external classical potential. We analyze, in particular, the VEV of the stress-energy tensor, the corresponding boundary forces and the total energy, thus taking into account both local and global aspects of the Casimir effect. In comparison with the wide existing literature on these subjects, we try to develop a more systematic approach, allowing to treat specific configurations by mere application of a general machinery. The present Part I is mainly devoted to setting up this general framework; at the end of the paper, this is exemplified in a very simple case. In Parts II, III and IV we will consider more engaging applications, indicated in the...
Hales, Jena B.; Ocampo, Amber C.; Broadbent, Nicola J.; Clark, Robert E.
2015-01-01
Spatial memory in rodents can be erased following the infusion of zeta inhibitory peptide (ZIP) into the dorsal hippocampus via indwelling guide cannulas. It is believed that ZIP impairs spatial memory by reversing established late-phase long-term potentiation (LTP). However, it is unclear whether other forms of hippocampus-dependent memory, such as recognition memory, are also supported by hippocampal LTP. In the current study, we tested recognition memory in rats following hippocampal ZIP infusion. In order to combat the limited targeting of infusions via cannula, we implemented a stereotaxic approach for infusing ZIP throughout the dorsal, intermediate, and ventral hippocampus. Rats infused with ZIP 3–7 days after training on the novel object recognition task exhibited impaired object recognition memory compared to control rats (those infused with aCSF). In contrast, rats infused with ZIP 1 month after training performed similar to control rats. The ability to form new memories after ZIP infusions remained intact. We suggest that enhanced recognition memory for recent events is supported by hippocampal LTP, which can be reversed by hippocampal ZIP infusion. PMID:26380123
Theodoratos, Angelo; Tu, Wen Juan; Cappello, Jean; Blackburn, Anneke C; Matthaei, Klaus; Board, Philip G
2009-04-15
Glutathione transferase Zeta (GSTZ1-1) is identical to maleylacetoacetate isomerase and catalyses a significant step in the catabolism of phenylalanine and tyrosine. Exposure of GSTZ1-1 deficient mice to high dietary phenylalanine causes a rapid loss of circulating white blood cells (WBCs). The loss was significant (P<0.05) after 2 days and total WBCs were reduced by 60% after 6 days. The rapid loss of WBCs was attributed to the accumulation of the catabolic intermediates maleylacetoacetate or maleylacetone (MA) in the circulation. Serum from GSTZ1-1 deficient mice treated with phenylalanine was cytotoxic to splenocytes from normal BALB/c mice and direct incubation of normal splenocytes with MA caused a rapid loss of viability. Dichloroacetic acid (DCA) has been used therapeutically to treat lactic acidosis and is potentially of use in cancer chemotherapy. Since DCA can inactivate GSTZ1-1 there is a possibility that long-term treatment of patients with DCA could cause GSTZ1-1 deficiency and susceptibility to oxidative stress and phenylalanine/tyrosine-induced WBC loss. However, although we found that DCA at 200mg/(kg day) causes a severe loss of hepatic GSTZ1-1 activity in BALB/c mice, it did not induce WBC cytotoxicity when combined with high dietary phenylalanine.
Palermo, Vincenzo; Liscio, Andrea; Talarico, Anna Maria; Zhi, Linjie; Müllen, Klaus; Samorì, Paolo
2007-06-15
Synthetic nanographenes have been self-assembled from solution on the surface of nanometric channels of an alumina membrane template. By controlling the interplay between intermolecular and interfacial interactions, the molecules have been adsorbed either 'face-on' or 'edge-on' on the pore's surfaces, leading to the formation of columnar stacks in the latter case. Upon thermal treatment at high temperature, the molecular cross-linking of the columns has been triggered, transforming the delicate supramolecular arrangement into robust carbon nanotubes, with the graphitic planes at predetermined orientations with respect to the tube axis. Scanning force microscopy characterization of single nanotubes deposited from suspensions on mica showed that the nanotubes can self-assemble on flat surfaces adopting preferential alignments which reflect the threefold symmetry of the mica substrate. Kelvin probe force microscopy studies revealed that the nanotubes possess a surface potential much smaller than the work function of both graphite and conventional vacuum-processed nanotubes, providing evidence for their more confined electronic structure.
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.
Study on the mixing of fluid in curved microchannels with heterogeneous surface potentials
Institute of Scientific and Technical Information of China (English)
Lin Jian-Zhong; Zhang Kai; Li Hui-Jun
2006-01-01
In this paper the mixing of a sample in the curved microchannel with heterogeneous surface potentials is analysed numerically by using the control-volume-based finite difference method. The rigorous models for describing the wall potential and external potential are solved to get the distribution of wall potential and external potential, then momentum equation is solved to get the fully developed flow field. Finally the mass transport equation is solved to get the concentration field. The results show that the curved microchannel has an optimized capability of sample mixing and transport when the heterogeneous surface is located at the left conjunction between the curved part and straight part. The variation of heterogeneous surface potential ψn has more influence on the capability of sample mixing than on that of sample transport. The ratio of the curved microchannel's radius to width has a comparable effect on the capability of sample mixing and transport. The conclusions above are helpful to the optimization of the design of microfluidic devices for the improvement of the efficiency of sample mixing.
DEFF Research Database (Denmark)
Geisler, C; Kuhlmann, J; Plesner, T;
1989-01-01
The T-cell antigen receptor is composed of two variable chains (alpha and beta, termed TcR) which confer ligand specificity, and four constant chains (gamma, delta, epsilon, and zeta, collectively termed CD3) whose functions are not fully understood. To explore the role of the individual CD3...... components, the human T-cell tumour line Jurkat was chemically mutagenized followed by negative selection with F101.01 (a monoclonal antibody against the TcR-CD3 complex), and cloning. Growing clones were analysed for TcR-CD3 expression by immunofluorescence. One clone, J79, was found to express greatly...... the normal intracellular fate of the TcR-CD3 complex, and that the CD3-zeta is necessary for the intracellular transport and expression at the cell surface of the TcR-CD3 complex....
Theoretical study of nonlinear triatomic molecular potential energy surfaces:Lie algebraic method
Institute of Scientific and Technical Information of China (English)
郑雨军; 丁世良
2000-01-01
Triatomic molecular potential energy surfaces (PES) are obtained by using coherent state to take the classical limits of algebraic Hamiltonian. The algebraic Hamiltonian for bent tria-tomic molecules can be obtained using Lie algebraic method (the expansion coefficients are obtained by fitting spectroscopic data). This PES is applied to H2O molecule, and good results are obtained.
Lunar Surface Electric Potential Changes Associated with Traversals through the Earth's Foreshock
Collier, Michael R.; Hills, H. Kent; Stubbs, Timothy J.; Halekas, Jasper S.; Delory, Gregory T.; Espley, Jared; Farrell, William M.; Freeman, John W.; Vondrak, Richard
2011-01-01
We report an analysis of one year of Suprathermal Ion Detector Experiment (SIDE) Total Ion Detector (TID) resonance events observed between January 1972 and January 1973. The study includes only those events during which upstream solar wind conditions were readily available. The analysis shows that these events are associated with lunar traversals through the dawn flank of the terrestrial magnetospheric bow shock. We propose that the events result from an increase in lunar surface electric potential effected by secondary electron emission due to primary electrons in the Earth's foreshock region (although primary ions may play a role as well). This work establishes (1) the lunar surface potential changes as the Moon moves through the terrestrial bow shock, (2) the lunar surface achieves potentials in the upstream foreshock region that differ from those in the downstream magnetosheath region, (3) these differences can be explained by the presence of energetic electron beams in the upstream foreshock region and (4) if this explanation is correct, the location of the Moon with respect to the terrestrial bow shock influences lunar surface potential.
DEFF Research Database (Denmark)
Cybulski, Hubert; Fernandez, Berta; Henriksen, Christian
2012-01-01
We evaluate the phenylacetylene-argon intermolecular potential energy surface by fitting a representative number of ab initio interaction energies to an analytic function. These energies are calculated at a grid of intermolecular geometries, using the CCSD(T) method and the aug-cc-pVDZ basis set ...
Fletcher, Katharyn; Dreuw, Andreas; Faraji, Shirin
2014-01-01
Pigment Yellow 101 (PY101) exhibits a rich photochemistry in its S-1 state as it undergoes excited state intramolecular proton transfer and trans-cis isomerizations upon photoexcitation. Relaxed scans of its potential energy surface are thus computed along the reaction paths connecting the six most
Uniyal, Shweta; Chand, Manesh; Joshi, Subodh; Semalty, P. D.
2016-05-01
The modified embedded atom method (MEAM) potential parameters have been employed to calculate the unrelaxed divacancy formation energy, binding energy and surface energies for low index planes in bcc transition metals. The calculated results of divacancy binding energy and vacancy formation energy compare well with experimental and other available calculated results.
Ab initio potential-energy surface and rovibrational states of the HCN-HCl complex
Avoird, A. van der; Pedersen, T.B.; Dhont, G.S.F.; Fernandez, B.; Koch, H.
2006-01-01
A four-dimensional intermolecular potential-energy surface has been calculated for the HCN-HCl complex, with the use of the coupled cluster method with single and double excitations and noniterative inclusion of triples. Data for more than 13 000 geometries were represented by an angular expansion i
Pafong, E.; Geske, J.; Drossel, B.
2016-09-01
We study the wetting properties of water on silica surfaces using molecular dynamics (MD) simulations. To describe the intermolecular interaction between water and silica atoms, two types of interaction potential models are used: the standard BródkA and Zerda (BZ) model and the Gulmen and Thompson (GT) model. We perform an in-depth analysis of the influence of the choice of the potential on the arrangement of the water molecules in partially filled pores and on top of silica slabs. We find that at moderate pore filling ratios, the GT silica surface is completely wetted by water molecules, which agrees well with experimental findings, while the commonly used BZ surface is less hydrophilic and is only partially wetted. We interpret our simulation results using an analytical calculation of the phase diagram of water in partially filled pores. Moreover, an evaluation of the contact angle of the water droplet on top of the silica slab reveals that the interaction becomes more hydrophilic with increasing slab thickness and saturates around 2.5-3 nm, in agreement with the experimentally found value. Our analysis also shows that the hydroaffinity of the surface is mainly determined by the electrostatic interaction, but the van der Waals interaction nevertheless is strong enough that it can turn a hydrophobic surface into a hydrophilic surface.
Spatial distribution of potential near surface moisture flux at Yucca Mountain
Energy Technology Data Exchange (ETDEWEB)
Flint, A.L.; Flint, L.E.
1994-12-31
An estimate of the areal distribution of present-day surface liquid moisture flux at Yucca Mountain was made using field measured water contents and laboratory measured rock properties. Using available data for physical and hydrologic properties (porosity, saturated hydraulic conductivity moisture retention functions) of the volcanic rocks, surface lithologic units that are hydrologically similar were delineated. Moisture retention and relative permeability functions were assigned to each surface unit based on the similarity of the mean porosity and saturated hydraulic conductivity of the surface unit to laboratory samples of the same lithology. The potential flux into the mountain was estimated for each surface hydrologic unit using the mean saturated hydraulic conductivity for each unit and assuming all matrix flow. Using measured moisture profiles for each of the surface units, estimates were made of the depth at which seasonal fluctuations diminish and steady state downward flux conditions are likely to exist. The hydrologic properties at that depth were used with the current relative saturation of the tuff, to estimate flux as the unsaturated hydraulic conductivity. This method assumes a unit gradient. The range in estimated flux was 0.02 mm/yr for the welded Tiva Canyon to 13.4 mm/yr for the nonwelded Paintbrush Tuff. The areally averaged flux was 1.4 mm/yr. The major zones of high flux occur to the north of the potential repository boundary where the nonwelded tuffs are exposed in the major drainages.
Spatial distribution of potential near surface moisture flux at Yucca Mountain
Energy Technology Data Exchange (ETDEWEB)
Flint, A.L.; Flint, L.E. [Geologic Survey, Mercury, NV (United States)
1994-12-31
An estimate of the areal distribution of present-day surface liquid moisture flux at Yucca Mountain was made using field measured water contents and laboratory measured rock properties. Using available data for physical and hydrologic properties (porosity, saturated hydraulic conductivity, moisture retention functions) of the volcanic rocks, surface lithologic units that are hydrologically similar were delineated. Moisture retention and relative permeability functions were assigned to each surface unit based on the similarity of the mean porosity and saturated hydraulic conductivity of the surface unit to laboratory samples of the same lithology. The potential flux into the mountain was estimated for each surface hydrologic unit using the mean saturated hydraulic conductivity for each unit and assuming all matrix flow. Using measured moisture profiles for each of the surface units, estimates were made of the depth at which seasonal fluctuations diminish and steady state downward flux conditions are likely to exist. The hydrologic properties at that depth were used with the current relative saturation of the tuff, to estimate flux as the unsaturated hydraulic conductivity. This method assumes a unit gradient. The range in estimated flux was 0.02 mm/yr for the welded Tiva Canyon to 13.4 mm/yr for the nonwelded Paintbrush Tuff. The areally averaged flux was 1.4 mm/yr. The major zones of high flux occur to the north of the potential repository boundary where the nonwelded tuffs are exposed in the major drainages.
Institute of Scientific and Technical Information of China (English)
XU Zhongming; HUANG Ping
2007-01-01
A method based on the energy dissipation mechanism of an Independent Oscillator model is used to calculate the frictional force and the friction coefficient of interfacial friction. The friction work is calculated with considering the potential change of contact surfaces during sliding. The potential change can be gained by a universal adhesive energy function. The relationships between frictional force and parameters of a tribo-system, such as surface energy and microstructure of interfacial material, are set up. The calculation results of the known experimental data denote that the frictional force is nearly proportional to the surface energy of the material, nearly inversely proportional to the scaling length, and independent of the lattice constant. The results agree with that of adhesion friction equations. They also agree with the experimental results performed with an atomic-force microscope under the ultra high vacuum condition.
Hess, P. O.; Ermamatov, M.
2017-07-01
Starting from the content of the shell model space and using a simple symplectic as a weight Hamiltonian, the relative positions of different symplectic irreducible representations are deduced. Applying a geometrical mapping leads to a microscopically derived Potential-Energy-Surface. After smoothing this surface and fitting a mass parameter to the first excited 6+-state in the ground state band, the spectrum of a nucleus can be reproduced qualitatively. The method is also used to obtain a first estimation of the quadrupole Potential Energy Surface of any nucleus, allowing to obtain information about the structure of the nucleus in question. Of special interest is the prediction of the structure of nuclei away from the valley of stability and of super-heavy nuclei. The method will be illustrated at184W. One objective is to show that the Pauli Exclusion Principle is the main driving force for the structure of a nucleus, though some further microscopic input has to be used.
AFM-assisted fabrication of thiol SAM pattern with alternating quantified surface potential
Directory of Open Access Journals (Sweden)
Simons Janet
2011-01-01
Full Text Available Abstract Thiol self-assembled monolayers (SAMs are widely used in many nano- and bio-technology applications. We report a new approach to create and characterize a thiol SAMs micropattern with alternating charges on a flat gold-coated substrate using atomic force microscopy (AFM and Kelvin probe force microscopy (KPFM. We produced SAMs-patterns made of alternating positively charged, negatively charged, and hydrophobic-terminated thiols by an automated AFM-assisted manipulation, or nanografting. We show that these thiol patterns possess only small topographical differences as revealed by AFM, and distinguished differences in surface potential (20-50 mV, revealed by KPFM. The pattern can be helpful in the development of biosensor technologies, specifically for selective binding of biomolecules based on charge and hydrophobicity, and serve as a model for creating surfaces with quantified alternating surface potential distribution.
Intrinsic Charge Trapping Observed as Surface Potential Variations in diF-TES-ADT Films.
Hoffman, Benjamin C; McAfee, Terry; Conrad, Brad R; Loth, Marsha A; Anthony, John E; Ade, Harald W; Dougherty, Daniel B
2016-08-24
Spatial variations in surface potential are measured with Kelvin probe force microscopy for thin films of 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophenes (diF-TES-ADT) grown on SiO2 and silane-treated SiO2 substrates by organic molecular beam deposition. The variations are observed both between and within grains of the polycrystalline organic film and are quantitatively different than electrostatic variations on the substrate surfaces. The skewness of surface potential distributions is larger on SiO2 than on HMDS-treated substrates. This observation is attributed to the impact of substrate functionalization on minimizing intrinsic crystallographic defects in the organic film that can trap charge.
Impact of organic overlayers on a-Si:H/c-Si surface potential
Seif, Johannes P.
2017-04-11
Bilayers of intrinsic and doped hydrogenated amorphous silicon, deposited on crystalline silicon (c-Si) surfaces, simultaneously provide contact passivation and carrier collection in silicon heterojunction solar cells. Recently, we have shown that the presence of overlaying transparent conductive oxides can significantly affect the c-Si surface potential induced by these amorphous silicon stacks. Specifically, deposition on the hole-collecting bilayers can result in an undesired weakening of contact passivation, thereby lowering the achievable fill factor in a finished device. We test here a variety of organic semiconductors of different doping levels, overlaying hydrogenated amorphous silicon layers and silicon-based hole collectors, to mitigate this effect. We find that these materials enhance the c-Si surface potential, leading to increased implied fill factors. This opens opportunities for improved device performance.
Ab initio potential energy and dipole moment surfaces of the F(-)(H2O) complex.
Kamarchik, Eugene; Toffoli, Daniele; Christiansen, Ove; Bowman, Joel M
2014-02-05
We present full-dimensional, ab initio potential energy and dipole moment surfaces for the F(-)(H2O) complex. The potential surface is a permutationally invariant fit to 16,114 coupled-cluster single double (triple)/aVTZ energies, while the dipole surface is a covariant fit to 11,395 CCSD(T)/aVTZ dipole moments. Vibrational self-consistent field/vibrational configuration interaction (VSCF/VCI) calculations of energies and the IR-spectrum are presented both for F(-)(H2O) and for the deuterated analog, F(-)(D2O). A one-dimensional calculation of the splitting of the ground state, due to equivalent double-well global minima, is also reported.
Refined potentials for rare gas atom adsorption on rare gas and alkali-halide surfaces
Wilson, J. W.; Heinbockel, J. H.; Outlaw, R. A.
1985-01-01
The utilization of models of interatomic potential for physical interaction to estimate the long range attractive potential for rare gases and ions is discussed. The long range attractive force is calculated in terms of the atomic dispersion properties. A data base of atomic dispersion parameters for rare gas atoms, alkali ion, and halogen ions is applied to the study of the repulsive core; the procedure for evaluating the repulsive core of ion interactions is described. The interaction of rare gas atoms on ideal rare gas solid and alkali-halide surfaces is analyzed; zero coverage absorption potentials are derived.
Proof of Analytic Extension Theorem for Zeta Function Using Abel Transformation and Euler Product
Directory of Open Access Journals (Sweden)
Mbaitiga Zacharie
2010-01-01
Full Text Available Problem statement: In the prime number the Riemann zeta function is unquestionable and undisputable one of the most important questions in mathematics whose many researchers are still trying to find answer to some unsolved problems such as Riemann Hypothesis. In this study we proposed a new method that proves the analytic extension theorem for zeta function. Approach: Abel transformation was used to prove that the extension theorem is true for the real part of the complex variable that is strictly greater than one and consequently provides the required analytic extension of the zeta function to the real part greater than zero and Euler product was used to prove the real part of the complex that are less than zero and greater or equal to one. Results: From this proposed study we noted that the real values of the complex variable are lying between zero and one which may help to understand the relation between zeta function and its properties and consequently can pay the way to solve some complex arithmetic problems including the Riemann Hypothesis. Conclusion: The combination of Abel transformation and Euler product is a powerful tool for proving theorems and functions related to Zeta function including other subjects such as radio atmospheric occultation.
Riemann Zeta Zeros and Prime Number Spectra in Quantum Field Theory
Menezes, G.; Svaiter, B. F.; Svaiter, N. F.
2013-10-01
The Riemann hypothesis states that all nontrivial zeros of the zeta function lie in the critical line Re(s) = 1/2. Hilbert and Pólya suggested that one possible way to prove the Riemann hypothesis is to interpret the nontrivial zeros in the light of spectral theory. Using the construction of the so-called super-zeta functions or secondary zeta functions built over the Riemann nontrivial zeros and the regularity property of one of this function at the origin, we show that it is possible to extend the Hilbert-Pólya conjecture to systems with countably infinite number of degrees of freedom. The sequence of the nontrivial zeros of the Riemann zeta function can be interpreted as the spectrum of a self-adjoint operator of some hypothetical system described by the functional approach to quantum field theory. However, if one considers the same situation with numerical sequences whose asymptotic distributions are not "far away" from the asymptotic distribution of prime numbers, the associated functional integral cannot be constructed. Finally, we discuss possible relations between the asymptotic behavior of a sequence and the analytic domain of the associated zeta function.
Identification and characterization of the interaction between tuberin and 14-3-3zeta.
Nellist, Mark; Goedbloed, Miriam A; de Winter, Christa; Verhaaf, Brenda; Jankie, Anita; Reuser, Arnold J J; van den Ouweland, Ans M W; van der Sluijs, Peter; Halley, Dicky J J
2002-10-18
Tuberous sclerosis is caused by mutations to either the TSC1 or TSC2 tumor suppressor gene. The disease is characterized by a broad phenotypic spectrum that includes seizures, mental retardation, renal dysfunction, and dermatological abnormalities. TSC1 encodes a 130-kDa protein called hamartin, and TSC2 encodes a 200-kDa protein called tuberin. Although it has been shown that hamartin and tuberin form a complex and mediate phosphoinositide 3-kinase/Akt-dependent phosphorylation of the ribosomal protein S6, it is not yet clear how inactivation of either protein leads to tuberous sclerosis. Therefore, to obtain additional insight into tuberin and hamartin function, yeast two-hybrid screening experiments were performed to identify proteins that interact with tuberin. One of the proteins identified was 14-3-3zeta, a member of the 14-3-3 protein family. The interaction between tuberin and 14-3-3zeta was confirmed in vitro and by co-immunoprecipitation; multiple sites within tuberin for 14-3-3zeta binding were identified; and it was determined that 14-3-3zeta associated with the tuberin-hamartin complex. Finally, it was shown that the tuberin/14-3-3zeta interaction is regulated by Akt-mediated phosphorylation of tuberin, providing insight into how tuberin may regulate phosphorylation of S6.
An ab initio potential energy surface and vibrational energy levels of HXeBr
Institute of Scientific and Technical Information of China (English)
Zheng Guo Huang; En Cui Yang; Dai Qian Xie
2008-01-01
A three-dimensional global potential energy surface for the electronic ground state of HXeBr molecule is constructed from morethan 4200 ab initio points. These points are generated using an internally contracted multi-reference configuration interactionmethod with the Davidson correction (icMRCI + Q) and large basis sets. The stabilities and dissociation barriers are identified fromthe potential energy surfaces. The three-body dissociation channel is found to be the dominate dissociation channel for HXeBr.Based on the obtained potentials, low-lying vibrational energy levels of HXeBr calculated using the Lanczos algorithm is found tobe in good agreement with the available experimental band origins.2008 Zheng Guo Huang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Goldman, N; Leforestier, C; Saykally, R J
2004-05-25
We present results of gas phase cluster and liquid water simulations from the recently determined VRT(ASP-W)III water dimer potential energy surface. VRT(ASP-W)III is shown to not only be a model of high ''spectroscopic'' accuracy for the water dimer, but also makes accurate predictions of vibrational ground-state properties for clusters up through the hexamer. Results of ambient liquid water simulations from VRT(ASP-W)III are compared to those from ab initio Molecular Dynamics, other potentials of ''spectroscopic'' accuracy, and to experiment. The results herein represent the first time that a ''spectroscopic'' potential surface is able to correctly model condensed phase properties of water.
Evenhuis, Christian; Martínez, Todd J
2011-12-14
Simulation of non-adiabatic molecular dynamics requires the description of multiple electronic state potential energy surfaces and their couplings. Ab initio molecular dynamics approaches provide an attractive avenue to accomplish this, but at great computational expense. Interpolation approaches provide a possible route to achieve flexible descriptions of the potential energy surfaces and their couplings at reduced expense. A previously developed approach based on modified Shepard interpolation required global diabatization, which can be problematic. Here, we extensively revise this previous approach, avoiding the need for global diabatization. The resulting interpolated potentials provide only adiabatic energies, gradients, and derivative couplings. This new interpolation approach has been integrated with the ab initio multiple spawning method and it has been rigorously validated against direct dynamics. It is shown that, at least for small molecules, constructing an interpolated PES can be more efficient than performing direct dynamics as measured by the total number of ab initio calculations that are required for a given accuracy.
Antarctic Ice Shelf Potentially Stabilized by Export of Meltwater in Surface River
Bell, Robin E.; Chu, Winnie; Kingslake, Jonathan; Das, Indrani; Tedesco, Marco; Tinto, Kirsty J.; Zappa, Christopher J.; Frezzotti, Massimo; Boghosian, Alexandra; Lee, Won Sang
2017-01-01
Meltwater stored in ponds and crevasses can weaken and fracture ice shelves, triggering their rapid disintegration. This ice-shelf collapse results in an increased flux of ice from adjacent glaciers and ice streams, thereby raising sea level globally. However, surface rivers forming on ice shelves could potentially export stored meltwater and prevent its destructive effects. Here we present evidence for persistent active drainage networks-interconnected streams, ponds and rivers-on the Nansen Ice Shelf in Antarctica that export a large fraction of the ice shelf's meltwater into the ocean. We find that active drainage has exported water off the ice surface through waterfalls and dolines for more than a century. The surface river terminates in a 130-metre-wide waterfall that can export the entire annual surface melt over the course of seven days. During warmer melt seasons, these drainage networks adapt to changing environmental conditions by remaining active for longer and exporting more water. Similar networks are present on the ice shelf in front of Petermann Glacier, Greenland, but other systems, such as on the Larsen C and Amery Ice Shelves, retain surface water at present. The underlying reasons for export versus retention remain unclear. Nonetheless our results suggest that, in a future warming climate, surface rivers could export melt off the large ice shelves surrounding Antarctica-contrary to present Antarctic ice-sheet models, which assume that meltwater is stored on the ice surface where it triggers ice-shelf disintegration.
Antarctic ice shelf potentially stabilized by export of meltwater in surface river
Bell, Robin E.; Chu, Winnie; Kingslake, Jonathan; Das, Indrani; Tedesco, Marco; Tinto, Kirsty J.; Zappa, Christopher J.; Frezzotti, Massimo; Boghosian, Alexandra; Lee, Won Sang
2017-04-01
Meltwater stored in ponds and crevasses can weaken and fracture ice shelves, triggering their rapid disintegration. This ice-shelf collapse results in an increased flux of ice from adjacent glaciers and ice streams, thereby raising sea level globally. However, surface rivers forming on ice shelves could potentially export stored meltwater and prevent its destructive effects. Here we present evidence for persistent active drainage networks—interconnected streams, ponds and rivers—on the Nansen Ice Shelf in Antarctica that export a large fraction of the ice shelf’s meltwater into the ocean. We find that active drainage has exported water off the ice surface through waterfalls and dolines for more than a century. The surface river terminates in a 130-metre-wide waterfall that can export the entire annual surface melt over the course of seven days. During warmer melt seasons, these drainage networks adapt to changing environmental conditions by remaining active for longer and exporting more water. Similar networks are present on the ice shelf in front of Petermann Glacier, Greenland, but other systems, such as on the Larsen C and Amery Ice Shelves, retain surface water at present. The underlying reasons for export versus retention remain unclear. Nonetheless our results suggest that, in a future warming climate, surface rivers could export melt off the large ice shelves surrounding Antarctica—contrary to present Antarctic ice-sheet models, which assume that meltwater is stored on the ice surface where it triggers ice-shelf disintegration.
Mezêncio, J M; Costa e Silva Filho, F; Rebello, M A
1997-01-01
Aedes albopictus cells possess a negative cell surface charge of -12.7 mV with an isoelectrophoretic point (IEP) located between pH 3.0 and 4.0. Infection with Mayaro virus rendered the surface of A. albopictus cells less negative reaching a zeta-potential value of -9.7 mV after 100 h of infection. Concomitantly, the IEP of the infected cells were also altered from 3.0-4.0 to 4.0-5.0. Furthermore, the contact angle measurements clearly showed qualitative alterations in the cell surface of infected cells.
A new non-destructive readout by using photo-recovered surface potential contrast.
Wang, Le; Jin, Kui-juan; Gu, Jun-xing; Ma, Chao; He, Xu; Zhang, Jiandi; Wang, Can; Feng, Yu; Wan, Qian; Shi, Jin-an; Gu, Lin; He, Meng; Lu, Hui-bin; Yang, Guo-zhen
2014-11-10
Ferroelectric random access memory is still challenging in the feature of combination of room temperature stability, non-destructive readout and high intensity storage. As a non-contact and non-destructive information readout method, surface potential has never been paid enough attention because of the unavoidable decay of the surface potential contrast between oppositely polarized domains. That is mainly due to the recombination of the surface movable charges around the domain walls. Here, by introducing a laser beam into the combination of piezoresponse force microscopy and Kelvin probe force microscopy, we demonstrate that the surface potential contrast of BiFeO3 films can be recovered under light illumination. The recovering mechanism is understood based on the redistribution of the photo-induced charges driven by the internal electric field. Furthermore, we have created a 12-cell memory pattern based on BiFeO3 films to show the feasibility of such photo-assisted non-volatile and non-destructive readout of the ferroelectric memory.
Ab Initio Potential Energy Surface and Internal Torsional-Wagging States of Hydroxylamine
Makarewicz; Kreglewski; Senent
1997-11-01
The two-dimensional potential energy surface describing the interaction of the large-amplitude torsional and wagging motions in hydroxylamine has been determined from ab initio calculations. This surface has been sampled by a large set of grid points from a two-dimensional configuration space spanned by the torsional and wagging coordinates. At each grid point, the geometry optimization has been performed using the second-order Moller-Plesset perturbation theory with the basis set 6-311 + G(2d, p). At the optimized geometry, the single-point calculation of the electronic energy has been carried out using a larger basis set 6-311 + G(3df, 2p). This method was verified to yield the results comparable to those obtained by a direct optimization of the geometry with the basis set 6-311 + G(3df, 2p) which had been used by A. Chung-Phillips and K. A. Jebber (1995. J. Chem. Phys. 102, 7080-7087) to calculate the energies of only three points in the potential energy surface of hydroxylamine. The trans and cis local minima have been found on the determined potential energy surface. The localization features of the torsional-wagging states have been studied by solving the two-dimensional Schrodinger equation for the coupled torsional and wagging motions. Copyright 1997 Academic Press. Copyright 1997Academic Press
Jarošová, Barbora; Javůrek, Jakub; Adamovský, Ondřej; Hilscherová, Klára
2015-08-01
This review discusses the potential contribution of phytoestrogens and mycoestrogens to in vitro estrogenic activities occurring in surface waters and in vivo estrogenic effects in fish. Main types, sources, and pathways of entry into aquatic environment of these detected compounds were summarized. Reviewed concentrations of phyto/mycoestrogens in surface waters were mostly undetectable or in low ng/L ranges, but exceeded tens of μg/L for the flavonoids biochanin A, daidzein and genistein at some sites. While a few phytosterols were reported to occur at relatively high concentrations in surface waters, information about their potencies in in vitro systems is very limited, and contradictory in some cases. The relative estrogenic activities of compounds (compared to standard estrogen 17β-estradiol) by various in vitro assays were included, and found to differ by orders of magnitude. These potencies were used to estimate total potential estrogenic activities based on chemical analyses of phyto/mycoestrogens. In vivo effective concentrations of waterborne phyto/mycoestrogens were available only for biochanin A, daidzein, formononetin, genistein, equol, sitosterol, and zearalenone. The lowest observable effect concentrations in vivo were reported for the mycoestrogen zearalenone. This compound and especially its metabolites also elicited the highest in vitro estrogenic potencies. Despite the limited information available, the review documents low contribution of phyto/mycoestrogens to estrogenic activity in vast majority of surface waters, but significant contribution to in vitro responses and potentially also to in vivo effects in areas with high concentrations.
Zeta-Functions for Families of Calabi--Yau n-folds with Singularities
Frühbis-Krüger, Anne
2011-01-01
We consider families of Calabi-Yau n-folds containing singular fibres and study relations between the occurring singularity structure and the decomposition of the local Weil zeta-function. For 1-parameter families, this provides new insights into the combinatorial structure of the strong equivalence classes arising in the Candelas - de la Ossa - Rodrigues-Villegas approach for computing the zeta-function. This can also be extended to families with more parameters as is explored in several examples, where the singularity analysis provides correct predictions for the changes of degree in the decomposition of the zeta-function when passing to singular fibres. These observations provide first evidence in higher dimensions for Lauder's conjectured analogue of the Clemens-Schmid exact sequence.
Uniform asymptotics for the full moment conjecture of the Riemann zeta function
Hiary, Ghaith A
2011-01-01
Conrey, Farmer, Keating, Rubinstein, and Snaith recently conjectured formulas for the full asymptotics of the moments of $L$-functions. In the case of the Riemann zeta function, their conjecture states that the $2k$-th absolute moment of zeta on the critical line is asymptotically given by a certain $2k$-fold residue integral. This residue integral can be expressed as a polynomial of degree $k^2$, whose coefficients are given in exact form by elaborate and complicated formulas. In this article, uniform asymptotics for roughly the first $k$ coefficients of the moment polynomial are derived. Numerical data to support our asymptotic formula are presented. An application to bounding the maximal size of the zeta function is considered.
Selberg zeta functions and transfer operators an experimental approach to singular perturbations
Fraczek, Markus Szymon
2017-01-01
This book presents a method for evaluating Selberg zeta functions via transfer operators for the full modular group and its congruence subgroups with characters. Studying zeros of Selberg zeta functions for character deformations allows us to access the discrete spectra and resonances of hyperbolic Laplacians under both singular and non-singular perturbations. Areas in which the theory has not yet been sufficiently developed, such as the spectral theory of transfer operators or the singular perturbation theory of hyperbolic Laplacians, will profit from the numerical experiments discussed in this book. Detailed descriptions of numerical approaches to the spectra and eigenfunctions of transfer operators and to computations of Selberg zeta functions will be of value to researchers active in analysis, while those researchers focusing more on numerical aspects will benefit from discussions of the analytic theory, in particular those concerning the transfer operator method and the spectral theory of hyperbolic spac...
Fujimoto, Minoru
2007-01-01
We consider a variant expression to regularize the Euler product representation of the zeta functions, where we mainly apply to that of the Riemann zeta function in this paper. The regularization itself is identical to that of the zeta function of the summation expression, but the non-use of the M\\"oebius function enable us to confirm a finite behavior of residual terms which means an absence of zeros except for the critical line. Same technique can be applied to the $L$-function associated to the elliptic curve, and we can deal with the Taylor expansion at the pole in critical strip which is deeply related to the Birch--Swinnerton-Dyer conjecture.
Ab initio intermolecular potential energy surfaces for the Ar-NCCN van der Waals complexes
Solimannejad, Mohammad; Jouypazadeh, Hamidreza; Farrokhpour, Hossein
2014-11-01
The intermolecular potential energy surface of complex pairing argon with cyanogen molecule (NCCN) was calculated using the coupled cluster with single and double and perturbative triple excitations (CCSD(T)) with aug-cc-pvdz basis set extended with a set of mid-bond (3s3p2d1f1g) functions. The interaction energies were calculated by the supermolecular approach with the full counterpoise correction for the basis set superposition error. The calculated potential energies were fitted to an analytical expression. The calculated Ar-NCCN potential energy surface shows a global minimum at 3.35 Å, the distance between argon and centre of mass of cyanogen, for the T-shaped geometry and two local minimum at distance of 5.54 Å for the linear geometry on one side of cyanogen. Finally, the interaction second virial coefficients were calculated using the fitted potential energy surface and were compared with those obtained by the parameters of the Beattie-Bridgeman equation of states of pure argon and cyanogens fluids, approximately.
Feet on the potential energy surface, head in the pi clouds
Energy Technology Data Exchange (ETDEWEB)
Smith, Quentin [Iowa State Univ., Ames, IA (United States)
2011-01-01
This work presents explorations of the potential energy surface of clusters of atoms and of the interactions between molecules. First, structures of small aluminum clusters are examined and classified as ground states, transition states, or higher-order saddle points. Subsequently, the focus shifts to dispersion-dominated π-π interactions when the potential energy surfaces of benzene, substituted benzene, and pyridine dimers are explored. Because DNA nucleotide bases can be thought of as substituted heterocycles, a natural extension of the substituted benzene and pyridine investigations is to model paired nucleotide bases. Finally, the success of the dispersion studies inspires the development of an extension to the computational method used, which will enable the dispersion energy to be modeled – and the potential energy surface explored – in additional chemical systems. The effective fragment potential (EFP) method is described, as well as various quantum mechanical methods. An ab inito quantum mechanical study of 13-atom aluminum clusters is described. EFP studies of aromatic dimers are reported in which dispersion energy makes a significant contribution to the attraction between monomers. Theory and code development toward a means of computing dispersion energy in mixed ab inito-EFP systems are described.
Matito, Eduard; Toffoli, Daniele; Christiansen, Ove
2009-04-01
In this work we develop and test a methodology for the generation of Born-Oppenheimer potential energy surfaces (PES) for use in vibrational structure calculations. The method relies on the widely used restricted-mode-coupling expansion of the fully coupled potential surface where only up to n or less vibrational coordinates are coupled in the potential. Low-order derivatives of the energy are then used to extrapolate the higher mode-coupling potential terms; derivative information is thus used in a convenient way for the evaluation of higher mode couplings avoiding their explicit calculation on multidimensional grids. The formulation, which is a variant of the popular modified Shepard interpolation, is general for any extrapolation of (n +p)-mode-coupling terms from n-mode couplings and can be applied to the energy or any other molecular property surface for which derivative information is available. The method depends only on analytical parameter-free weight functions that satisfy important limiting conditions and control the contribution from each direction of extrapolation. The procedure has been applied on a representative set of 13 molecules, and its accuracy has been tested using only gradients and using both gradients and Hessians. The results provide evidence for the importance of higher mode couplings and illustrate the cost efficiency of the proposed approach.
Assessing Potential Land Suitability for Surface Irrigation using Groundwater in Ethiopia
Worqlul, A. W.; Jeong, J.; Osorio, J.; Gerik, T.; Yihun, D.; Srinivan, R.; Clark, N.
2016-12-01
Although Ethiopia has large land areas that can potentially be developed for surface irrigation, only a fraction of the potential available land has been utilized. This paper presents evaluation of the potential lands in Ethiopia that are suitable for irrigation using groundwater. The suitable land was identified using GIS-based Multi-Criteria Evaluation (MCE) techniques applying a GIS model. The factors used were identified from literature and from experts in the region. Factors considered includes physical land features (land use, soil and slope), climate characteristics (rainfall and evapotranspiration), and market access (proximity to roads and access to market). Factors were weighted using a pair-wise comparison matrix, reclassified, and overlaid to identify the suitable areas for groundwater irrigation at 1 km grid. Groundwater data from the British Geological Survey were used to estimate potential groundwater availability and analyze the irrigation potential for dominant crops. Simulated output from SWAT could be used in areas where data is not available. Result indicates that approximately 6.0 million ha of land in Ethiopia is suitable for surface irrigation. A large portion of this suitable land is located in the Abbay, Rift Valley, Omo Ghibe, and Awash River basins, which all also have shallow groundwater access (< 20 m from the surface). The comparison between available groundwater and total crop water requirements indicated that current groundwater resources in the basins are not capable of irrigating all suitable land independently, but groundwater resources are a good option for supplementing current surface water resources in many regions. The study indicated that only 8 % of the suitable land could be irrigated with the groundwater within the grid.
Surface-active biopolymers from marine bacteria for potential biotechnological applications
Directory of Open Access Journals (Sweden)
Karina Sałek
2016-03-01
Full Text Available Surface-active agents are amphiphilic chemicals that are used in almost every sector of modern industry, the bulk of which are produced by organo-chemical synthesis. Those produced from biological sources (biosurfactants and bioemulsifiers, however, have gained increasing interest in recent years due to their wide structural and functional diversity, lower toxicities and high biodegradability, compared to their chemically-synthesised counterparts. This review aims to present a general overview on surface-active agents, including their classification, where new types of these biomolecules may lay awaiting discovery, and some of the main bottlenecks for their industrial-scale production. In particular, the marine environment is highlighted as a largely untapped source for discovering new types of surface-active agents. Marine bacteria, especially those living associated with micro-algae (eukaryotic phytoplankton, are a highly promising source of polymeric surface-active agents with potential biotechnological applications. The high uronic acids content of these macromolecules has been linked to conferring them with amphiphilic qualities, and their high structural diversity and polyanionic nature endows them with the potential to exhibit a wide range of functional diversity. Production yields (e.g. by fermentation for most microbial surface-active agents have often been too low to meet the volume demands of industry, and this principally remains as the most important bottleneck for their further commercial development. However, new developments in recombinant and synthetic biology approaches can offer significant promise to alleviate this bottleneck. This review highlights a particular biotope in the marine environment that offers promise for discovering novel surface-active biomolecules, and gives a general overview on specific areas that researchers and the industry could focus work towards increasing the production yields of microbial surface
Finding zeros of the Riemann zeta function by periodic driving of cold atoms
Creffield, C. E.; Sierra, G.
2015-06-01
The Riemann hypothesis, which states that the nontrivial zeros of the Riemann zeta function all lie on a certain line in the complex plane, is one of the most important unresolved problems in mathematics. We propose here an approach to finding a physical system to study the Riemann zeros, which is based on applying a time-periodic driving field. This driving allows us to tune the quasienergies of the system (the analog of the eigenenergies for static systems), so that they are directly governed by the zeta function. We further show by numerical simulations that this allows the Riemann zeros to be measured in currently accessible cold-atom experiments.
Roots of the derivative of the Riemann zeta function and of characteristic polynomials
Dueñez, Eduardo; Froehlich, Sara; Hughes, Chris; Mezzadri, Francesco; Phan, Toan
2010-01-01
We investigate the horizontal distribution of zeros of the derivative of the Riemann zeta function and compare this to the radial distribution of zeros of the derivative of the characteristic polynomial of a random unitary matrix. Both cases show a surprising bimodal distribution which has yet to be explained. We show by example that the bimodality is a general phenomenon. For the unitary matrix case we prove a conjecture of Mezzadri concerning the leading order behavior, and we show that the same follows from the random matrix conjectures for the zeros of the zeta function.
Vieru, Andrei
2016-01-01
The renormalization of MZV was until now carried out by algebraic means. In this paper, we show that renormalization in general, and in particular of the multiple zeta functions, is more than just a pure algebraic convention. We give a simple analytic method of computing the regularized values of multiple zeta functions in any dimension for arguments of the form (1,...,1), where the series do not converge. These values happen to be the coefficients of the asymptotic expansion of the inverse G...
Can Time-Dependent Zeta Correlators be Swept under the Rug?
Boran, Sibel
2016-01-01
We discuss quantum gravitational loop effects to observable quantities such as curvature power spectrum and primordial non-gaussianity of Cosmic Microwave Background (CMB) radiation. We first review the previously shown case where one gets a time dependence for zeta-zeta correlator due to loop corrections. Then we investigate the effect of these loop corrections to primordial non-gaussianity of CMB. We conclude that with a single scalar inflaton one gets a huge value for non-gaussianity which exceeds the observed value by at least 30 orders of magnitude. Finally we discuss the consequences of this result for scalar driven inflationary models.
Zeta Function Regularization in Casimir Effect Calculations and J. S. Dowker's Contribution
Elizalde, Emilio
2012-07-01
A summary of relevant contributions, ordered in time, to the subject of operator zeta functions and their application to physical issues is provided. The description ends with the seminal contributions of Stephen Hawking and Stuart Dowker and collaborators, considered by many authors as the actual starting point of the introduction of zeta function regularization methods in theoretical physics, in particular, for quantum vacuum fluctuation and Casimir effect calculations. After recalling a number of the strengths of this powerful and elegant method, some of its limitations are discussed. Finally, recent results of the so called operator regularization procedure are presented.
Energy Technology Data Exchange (ETDEWEB)
Lee, Myoung-Jae [Department of Physics, Hanyang University, Seoul 04763 (Korea, Republic of); Research Institute for Natural Sciences, Hanyang University, Seoul 04763 (Korea, Republic of); Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr [Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 15588 (Korea, Republic of); Department of Electrical and Computer Engineering, MC 0407, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0407 (United States)
2017-02-12
High frequency electrostatic wave propagation in a dense and semi-bounded electron quantum plasma is investigated with consideration of the Bohm potential. The dispersion relation for the surface mode of quantum plasma is derived and numerically analyzed. We found that the quantum effect enhances the frequency of the wave especially in the high wave number regime. However, the frequency of surface wave is found to be always lower than that of the bulk wave for the same quantum wave number. The group velocity of the surface wave for various quantum wave number is also obtained. - Highlights: • High frequency electrostatic wave propagation is investigated in a dense semi-bounded quantum plasma. • The dispersion relation for the surface mode of quantum plasma is derived and numerically analyzed. • The quantum effect enhances the frequency of the wave especially in the high wave number regime. • The frequency of surface wave is found to be always lower than that of the bulk wave. • The group velocity of the surface wave for various quantum wave number is also obtained.
An SCF-CI method for determining the potential energy surface of a triatomic molecule
Institute of Scientific and Technical Information of China (English)
谢代前; 鄢国森
1996-01-01
A self-consistent-field (SCF)-configuration interaction (CI) (SCF-CI) method for determining the potential energy surface of a triatomic molecule from the observed vibrational band origins has been suggested. By this method, the SCF-CI procedure in the internal coordinates is used to calculate the vibrational bond origins and their first derivatives with respect to parameters in the potential energy function using the exact vibrational Hamiltonian, and the optimizer LMF in the nonlinear-squares problem is employed to optimize parameters in the potential energy function. This approach is used to optimize the potential energy function of the water molecule. The standard deviation of this fitting to the 70 observed band origins is 1.154cm-1.
Energy Technology Data Exchange (ETDEWEB)
Okada, Masashi; Hozumi, Yasukazu [Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata 990-9585 (Japan); Ichimura, Tohru [Department of Chemistry, Graduate School of Sciences and Engineering, Tokyo Metropolitan University, Hachioji 192-0397 (Japan); Tanaka, Toshiaki; Hasegawa, Hiroshi; Yamamoto, Masakazu; Takahashi, Nobuya [Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata 990-9585 (Japan); Iseki, Ken [Department of Emergency and Critical Care Medicine, Yamagata University School of Medicine, Yamagata 990-9585 (Japan); Yagisawa, Hitoshi [Laboratory of Biological Signaling, Graduate School of Life Science, University of Hyogo, Hyogo 678-1297 (Japan); Shinkawa, Takashi; Isobe, Toshiaki [Department of Chemistry, Graduate School of Sciences and Engineering, Tokyo Metropolitan University, Hachioji 192-0397 (Japan); Goto, Kaoru, E-mail: kgoto@med.id.yamagata-u.ac.jp [Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata 990-9585 (Japan)
2011-12-10
Diacylglycerol kinase (DGK) is involved in the regulation of lipid-mediated signal transduction through the metabolism of a second messenger diacylglycerol. Of the DGK family, DGK{zeta}, which contains a nuclear localization signal, localizes mainly to the nucleus but translocates to the cytoplasm under pathological conditions. However, the detailed mechanism of translocation and its functional significance remain unclear. To elucidate these issues, we used a proteomic approach to search for protein targets that interact with DGK{zeta}. Results show that nucleosome assembly protein (NAP) 1-like 1 (NAP1L1) and NAP1-like 4 (NAP1L4) are identified as novel DGK{zeta} binding partners. NAP1Ls constitutively shuttle between the nucleus and the cytoplasm in transfected HEK293 cells. The molecular interaction of DGK{zeta} and NAP1Ls prohibits nuclear import of DGK{zeta} because binding of NAP1Ls to DGK{zeta} blocks import carrier proteins, Qip1 and NPI1, to interact with DGK{zeta}, leading to cytoplasmic tethering of DGK{zeta}. In addition, overexpression of NAP1Ls exerts a protective effect against doxorubicin-induced cytotoxicity. These findings suggest that NAP1Ls are involved in a novel molecular basis for the regulation of nucleocytoplasmic shuttling of DGK{zeta} and provide a clue to examine functional significance of its translocation under pathological conditions.
Energy Technology Data Exchange (ETDEWEB)
Trujillo, John I.; Kiefer, James R.; Huang, Wei; Thorarensen, Atli; Xing, Li; Caspers, Nicole L.; Day, Jacqueline E.; Mathis, Karl J.; Kretzmer, Kuniko K.; Reitz, Beverley A.; Weinberg, Robin A.; Stegeman, Roderick A.; Wrightstone, Ann; Christine, Lori; Compton, Robert; Li, Xiong; (Pfizer)
2009-03-16
The inhibition of PKC-{zeta} has been proposed to be a potential drug target for immune and inflammatory diseases. A series of 2-(6-phenyl-1H indazol-3-yl)-1H-benzo[d]imidazoles with initial high crossover to CDK-2 has been optimized to afford potent and selective inhibitors of protein kinase c-zeta (PKC-{zeta}). The determination of the crystal structures of key inhibitor:CDK-2 complexes informed the design and analysis of the series. The most selective and potent analog was identified by variation of the aryl substituent at the 6-position of the indazole template to give a 4-NH{sub 2} derivative. The analog displays good selectivity over other PKC isoforms ({alpha}, {beta}II, {gamma}, {delta}, {epsilon}, {mu}, {theta}, {eta} and {ell}/{lambda}) and CDK-2, however it displays marginal selectivity against a panel of other kinases (37 profiled).
STM investigations of local potential barrier distribution of the atomic surface of graphite
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
To modulate the tunneling gap with the lock-in amplifier in the scanning tunneling microscopy(STM), information of the tunneling current variation can be obtained. The local potential barrier distribution of graphite surface atoms is got by means of such technology. Compared with STM image under topography observation mode, the local potential barrier image has higher resolu tion and less influence on the tip and better anti-interference capability. Obs erved results of the graphite are given and discussed in this paper.
Computed potential surfaces for six low-lying states of Ni3
Walch, Stephen P.
1987-01-01
Selected portions of the potential surfaces for six low lying states of Ni3 are the subject of the present SCF/CCI calculations using the effective core potentials developed by Hay and Wadt (1985); the four states are studied for near-equilateral triangle geometries are within 0.04 eV of each other. Two states are studied for linear geometries, of which the first is 0.16 eV higher than the corresponding near-equilateral triangle state and the second is estimated to be nearly degenerate with the near-equilateral triangle structures.
Physisorbed H{sub 2}@Cu(100) surface: Potential and spectroscopy
Energy Technology Data Exchange (ETDEWEB)
Bernard, Eddy; Houriez, Céline; Mitrushchenkov, Alexander O.; Guitou, Marie; Chambaud, Gilberte, E-mail: gilberte.chambaud@univ-mlv.fr [Université Paris-Est, Laboratoire Modélisation et Simulation Multi-Echelle, UMR 8208 CNRS, 5 Boulevard Descartes, Champs sur Marne, F-77454 Marne-la-Vallée (France)
2015-02-07
Using an embedding approach, a 2-D potential energy function has been calculated to describe the physisorption interaction of H{sub 2} with a Cu(100) surface. For this purpose, a cluster model of the system calculated with highly correlated wavefunctions is combined with a periodic Density-Functional-Theory method using van der Waals-DF2 functional. Rotational and vibrational energy levels of physisorbed H{sub 2}, as well as D{sub 2} and HD, are calculated using the 2D embedding corrected potential energy function. The calculated transitions are in a very good agreement with Electron-Energy-Loss-Spectroscopy observations.
Hodnik, Nejc; Baldizzone, Claudio; Polymeros, George; Geiger, Simon; Grote, Jan-Philipp; Cherevko, Serhiy; Mingers, Andrea; Zeradjanin, Aleksandar; Mayrhofer, Karl J. J.
2016-01-01
The recycling of precious metals, for example, platinum, is an essential aspect of sustainability for the modern industry and energy sectors. However, due to its resistance to corrosion, platinum-leaching techniques rely on high reagent consumption and hazardous processes, for example, boiling aqua regia; a mixture of concentrated nitric and hydrochloric acid. Here we demonstrate that complete dissolution of metallic platinum can be achieved by induced surface potential alteration, an ‘electrode-less' process utilizing alternatively oxidative and reductive gases. This concept for platinum recycling exploits the so-called transient dissolution mechanism, triggered by a repetitive change in platinum surface oxidation state, without using any external electric current or electrodes. The effective performance in non-toxic low-concentrated acid and at room temperature is a strong benefit of this approach, potentially rendering recycling of industrial catalysts, including but not limited to platinum-based systems, more sustainable. PMID:27767178
Hodnik, Nejc; Baldizzone, Claudio; Polymeros, George; Geiger, Simon; Grote, Jan-Philipp; Cherevko, Serhiy; Mingers, Andrea; Zeradjanin, Aleksandar; Mayrhofer, Karl J. J.
2016-10-01
The recycling of precious metals, for example, platinum, is an essential aspect of sustainability for the modern industry and energy sectors. However, due to its resistance to corrosion, platinum-leaching techniques rely on high reagent consumption and hazardous processes, for example, boiling aqua regia; a mixture of concentrated nitric and hydrochloric acid. Here we demonstrate that complete dissolution of metallic platinum can be achieved by induced surface potential alteration, an `electrode-less' process utilizing alternatively oxidative and reductive gases. This concept for platinum recycling exploits the so-called transient dissolution mechanism, triggered by a repetitive change in platinum surface oxidation state, without using any external electric current or electrodes. The effective performance in non-toxic low-concentrated acid and at room temperature is a strong benefit of this approach, potentially rendering recycling of industrial catalysts, including but not limited to platinum-based systems, more sustainable.
Directory of Open Access Journals (Sweden)
Ashraf Khademzadeh
2014-01-01
Full Text Available The mechanism of S+O4 (D2h reaction has been investigated at the B3LYP/6-311+G(3df and CCSD levels on the singlet potential energy surface. One stable complex has been found for the S+O4 (D2h reaction, IN1, on the singlet potential energy surface. For the title reaction, we obtained four kinds of products at the B3LYP level, which have enough thermodynamic stability. The results reveal that the product P3 is spontaneous and exothermic with −188.042 and −179.147 kcal/mol in Gibbs free energy and enthalpy of reaction, respectively. Because P1 adduct is produced after passing two low energy level transition states, kinetically, it is the most favorable adduct in the 1S+1O4 (D2h atmospheric reactions.
Modification of transition's factor in the compact surface-potential-based MOSFET model
Directory of Open Access Journals (Sweden)
Kevkić Tijana
2016-01-01
Full Text Available The modification of an important transition's factor which enables continual behavior of the surface potential in entire useful range of MOSFET operation is presented. The various modifications have been made in order to obtain an accurate and computationally efficient compact MOSFET model. The best results have been achieved by introducing the generalized logistic function (GL in fitting of considered factor. The smoothness and speed of the transition of the surface potential from the depletion to the strong inversion region can be controlled in this way. The results of the explicit model with this GL functional form for transition's factor have been verified extensively with the numerical data. A great agreement was found for a wide range of substrate doping and oxide thickness. Moreover, the proposed approach can be also applied on the case where quantum mechanical effects play important role in inversion mode.
Potential areas for the near surface disposal of radioactive waste in Pahang
Harun, Nazran; Yaacob, Wan Zuhairi Wan; Simon, Norbert
2016-11-01
Radioactive material has been used in Malaysia since the 1960's. The low level radioactive wastes are generated every year and stored in Nuclear Malaysia. The storage capacities are expected to reach its maximum capacity by the year 2025. Disposal of the radioactive waste is considered as one of the best options for future radioactive and nuclear material generated in Malaysia, hence the necessary site selection. The selection process used the IAEA document as the main reference, supported by site selection procedure applied by various countries. ArcGIS software was used to simulate the selection of the near surface radioactive waste disposal. This paper suggested the best four potential areas for the near surface radioactive waste disposal in Pahang state, Malaysia, the Sg. Lembing, Gambang, Felda Lepar Utara and Cheneh areas. These areas are located within 100 km from the potential radioactive waste producer (Lynas).
Guduru, Deepak; Niepel, Marcus; Vogel, Jürgen; Groth, Thomas
2011-10-01
Nanostructures play important roles in vivo, where nanoscaled features of extracellular matrix (ECM) components influence cell behavior and resultant tissue formation. This review summarizes some of the recent developments in fostering new concepts and approaches to nanofabrication, such as top-down and bottom-up and combinations of the two. As in vitro investigations demonstrate that man-made nanotopography can be used to control cell reactions to a material surface, its potential application in implant design and tissue engineering becomes increasingly evident. Therefore, we present recent progress in directing cell fate in the field of cell mechanics, which has grown rapidly over the last few years, and in various tissue-engineering applications. The main focus is on the initial responses of cells to nanostructured surfaces and subsequent influences on cellular functions. Specific examples are also given to illustrate the potential nanostructures may have for biomedical applications and regenerative medicine.
Wan, Li; Xu, Shixin; Liao, Maijia; Liu, Chun; Sheng, Ping
2014-01-01
In this work, we treat the Poisson-Nernst-Planck (PNP) equations as the basis for a consistent framework of the electrokinetic effects. The static limit of the PNP equations is shown to be the charge-conserving Poisson-Boltzmann (CCPB) equation, with guaranteed charge neutrality within the computational domain. We propose a surface potential trap model that attributes an energy cost to the interfacial charge dissociation. In conjunction with the CCPB, the surface potential trap can cause a surface-specific adsorbed charge layer σ. By defining a chemical potential μ that arises from the charge neutrality constraint, a reformulated CCPB can be reduced to the form of the Poisson-Boltzmann equation, whose prediction of the Debye screening layer profile is in excellent agreement with that of the Poisson-Boltzmann equation when the channel width is much larger than the Debye length. However, important differences emerge when the channel width is small, so the Debye screening layers from the opposite sides of the channel overlap with each other. In particular, the theory automatically yields a variation of σ that is generally known as the "charge regulation" behavior, attendant with predictions of force variation as a function of nanoscale separation between two charged surfaces that are in good agreement with the experiments, with no adjustable or additional parameters. We give a generalized definition of the ζ potential that reflects the strength of the electrokinetic effect; its variations with the concentration of surface-specific and surface-nonspecific salt ions are shown to be in good agreement with the experiments. To delineate the behavior of the electro-osmotic (EO) effect, the coupled PNP and Navier-Stokes equations are solved numerically under an applied electric field tangential to the fluid-solid interface. The EO effect is shown to exhibit an intrinsic time dependence that is noninertial in its origin. Under a step-function applied electric field, a
Sánchez, Alemao G Carpinteyro; Virginio, Veridiana Gomes; Maschio, Vinicius José; Ferreira, Henrique Bunselmeyer; Rott, Marilise Brittes
2016-10-01
Acanthamoeba spp. are free-living protists widely distributed in environment, able to cause keratitis, encephalitis and skin lesions in humans and animals. Acanthamoeba spp. exist in two forms: an infective trophozoite and a dormant cyst. Several factors contribute to the pathogenesis of Acanthamoeba spp. The parasite adhesion to the host cell is the primary step for infection and is mediated by a mannose binding-protein, expressed in the surface and considered the main pathogenicity factor in Acanthamoeba spp. So far, there was no evidence of another surface protein of Acanthamoeba spp. relevant for host invasion or infection by these organisms. The aims of this study were to identify and characterize an Acanthamoeba castellanii surface protein and to evaluate its diagnostic potential. In silico predictions of surface proteins allowed to identify the A. castellanii calreticulin as a possible surface antigen. The coding sequence of a predicted extracellular domain of A. castellanii calreticulin was cloned by in vivo homologous recombination and the recombinant polypeptide (AcCRT29-130) was produced. Its immunodiagnostic potential was assessed in a recombinant antigen-based ELISA with sera from experimentally infected rats that developed keratitis and encephalitis, and sera from patients with encephalitis. The AcCRT29-130 was significantly more recognized by sera from encephalitis infected rats in comparison with the non-infected controls. Human sera from encephalitis patients, however presented no significant response. These results showed the AcCRT29-130 potential for A. castellanii infection immunodiagnosis in animals, with further studies being required for assessment of its use for human infections.
Topology of the Adiabatic Potential Energy Surfaces for theResonance States of the Water Anion
Energy Technology Data Exchange (ETDEWEB)
Haxton, Daniel J.; Rescigno, Thomas N.; McCurdy, C. William
2005-04-15
The potential energy surfaces corresponding to the long-lived fixed-nuclei electron scattering resonances of H{sub 2}O relevant to the dissociative electron attachment process are examined using a combination of ab initio scattering and bound-state calculations. These surfaces have a rich topology, characterized by three main features: a conical intersection between the {sup 2}A{sub 1} and {sup 2}B{sub 2} Feshbach resonance states; charge-transfer behavior in the OH ({sup 2}{Pi}) + H{sup -} asymptote of the {sup 2}B{sub 1} and {sup 2}A{sub 1} resonances; and an inherent double-valuedness of the surface for the {sup 2}B{sub 2} state the C{sub 2v} geometry, arising from a branch-point degeneracy with a {sup 2}B{sub 2} shape resonance. In total, eight individual seams of degeneracy among these resonances are located.
Surface Potential Control on Thin Oxide Films with Respect to Electron Stimulated Desorption Studies
Bernheim, Marc; Rousse, Gilles
1995-09-01
These experiments deal with the study of desorption of negative ions stimulated by low energy electron collisions on insulating surfaces covered with various adsorbates. For such investigation a careful control of the sample surface potential is required to set the incident electron energy accurately as well as to identify the desorbed species by mass spectrometry. Most of the reported experiments concern this surface potential control. We show that, for very thin SiO2 films thermally grown on silicon substrates, a tunnel conduction might set the surface potential accurately. This assertion mainly relies on recording the intensity of electrons transmitted through thin oxides as well as the intensity of backscattered and secondary electrons re-emitted from the surface. A direct comparison of the O^- ion energy distributions confirms the correct control of the surface potential for a large range of incident electron energies. In such condition we noticed that the O^- desorption yields just swiftly varied with incident electron energy. In particular no modification could be detected as the incident electron energy passed the various Auger excitation levels. The discrepancy between this last result and the published data is discussed in the last part of this paper. Des collisions électroniques sur des surfaces peuvent provoquer une éjection d'ions négatifs formés à partir des molécules adsorbées suivant un processus résonnant à très basse énergie. Pour étendre ces études expérimentales aux surfaces isolantes, un contrôle précis du potentiel superficiel devient indispensable tant pour fixer l'énergie finale des électrons sur la surface que pour effectuer la spectrométrie des ions désorbés. L'examen de surfaces de silice en couche mince montre comment une conduction tunnel intervient pour fixer le potentiel des surfaces examinées. Ces travaux expérimentaux effectués dans une configuration de miroir électrostatique reposent principalement sur l
Directory of Open Access Journals (Sweden)
Żak Krzysztof
2017-06-01
Full Text Available This paper presents a comprehensive methodology for measuring and characterizing the surface topographies on machined steel parts produced by precision machining operations. The performed case studies concern a wide spectrum of topographic features of surfaces with different geometrical structures but the same values of the arithmetic mean height Sa. The tested machining operations included hard turning operations performed with CBN tools, grinding operations with Al2O3 ceramic and CBN wheels and superfinish using ceramic stones. As a result, several characteristic surface textures with the Sa roughness parameter value of about 0.2 μm were thoroughly characterized and compared regarding their potential functional capabilities. Apart from the standard 2D and 3D roughness parameters, the fractal, motif and frequency parameters were taken in the consideration.
Tymoczko, Jakub; Schuhmann, Wolfgang; Gebala, Magdalena
2014-12-24
Surface-confined DNA hybridization reactions are sensitive to the number and identity of DNA capture probes and experimental conditions such as the nature and the ionic strength of the electrolyte solution. When the surface probe density is high or the concentration of bulk ions is much lower than the concentration of ions within the DNA layer, hybridization is significantly slowed down or does not proceed at all. However, high-density DNA monolayers are attractive for designing high-sensitivity DNA sensors. Thus, circumventing sluggish DNA hybridization on such interfaces allows a high surface concentration of target DNA and improved signal/noise ratio. We present potential-assisted hybridization as a strategy in which an external voltage is applied to the ssDNA-modified interface during the hybridization process. Results show that a significant enhancement of hybridization can be achieved using this approach.
Directory of Open Access Journals (Sweden)
P.S. Vanzillotta
2004-09-01
Full Text Available Bone formation around a metallic implant is a complex process that involves micro- and nanometric interactions. Several surface treatments, including coatings were developed in order to obtain faster osseointegration. To understand the role of these surface treatments on bone formation it is necessary to choose adequate characterization techniques. Among them, we have selected electron microscopy, profilometry, atomic force microscopy (AFM and X-ray photoelectron spectroscopy (XPS to describe them briefly. Examples of the potentialities of these techniques on the characterization of titanium for biomedical applications were also presented and discussed. Unfortunately more than one technique is usually necessary to describe conveniently the topography (scanning electron microsocopy, profilometry and/or AFM and the chemical state (XPS of the external layer of the material surface. The employment of the techniques above described can be useful especially for the development of new materials or products.
Rotational Energy Transfer of N2 Gas Determined Using a New Ab Initio Potential Energy Surface
Huo, Winifred M.; Stallcop, James R.; Partridge, Harry; Langhoff, Stephen R. (Technical Monitor)
1997-01-01
Rotational energy transfer between two N2 molecules is a fundamental process of some importance. Exchange is expected to play a role, but its importance is somewhat uncertain. Rotational energy transfer cross sections of N2 also have applications in many other fields including modeling of aerodynamic flows, laser operations, and linewidth analysis in nonintrusive laser diagnostics. A number of N2-N2 rigid rotor potential energy surface (PES) has been reported in the literature.
The impact of sea surface currents in wave power potential modeling
Zodiatis, George; Galanis, George; Kallos, George; Nikolaidis, Andreas; Kalogeri, Christina; Liakatas, Aristotelis; Stylianou, Stavros
2015-11-01
The impact of sea surface currents to the estimation and modeling of wave energy potential over an area of increased economic interest, the Eastern Mediterranean Sea, is investigated in this work. High-resolution atmospheric, wave, and circulation models, the latter downscaled from the regional Mediterranean Forecasting System (MFS) of the Copernicus marine service (former MyOcean regional MFS system), are utilized towards this goal. The modeled data are analyzed by means of a variety of statistical tools measuring the potential changes not only in the main wave characteristics, but also in the general distribution of the wave energy and the wave parameters that mainly affect it, when using sea surface currents as a forcing to the wave models. The obtained results prove that the impact of the sea surface currents is quite significant in wave energy-related modeling, as well as temporally and spatially dependent. These facts are revealing the necessity of the utilization of the sea surface currents characteristics in renewable energy studies in conjunction with their meteo-ocean forecasting counterparts.
Directory of Open Access Journals (Sweden)
M. Beekmann
2009-11-01
Full Text Available A tracer study has been performed for two summers in 2003 and 2004 with a regional chemistry-transport model in order to evaluate the potential constraint that tropospheric ozone observations from nadir viewing infrared sounders like IASI or TES exert on modelled near surface ozone. As these instruments show high sensitivity in the free troposphere, but low sensitivity at ground, it is important to know how much of the information gained in the free troposphere is transferred to ground through vertical transport processes. Within the European model domain, and within a time span of 4 days, only ozone like tracers initialised in vertical layers above 500 hPa are transported to the surface. For a tracer initialised between 800 and 700 hPa, seven percent reaches the surface within one to three days, on the average over the European model domain but more than double over the Mediterranean Sea. For this region, trajectory analysis shows that this is related to strong subsident transport. These results are confirmed by a second tracer study taking into account averaging kernels related to IASI retrievals, indicating the potential of these measurements to efficiently constrain surface ozone values.
Phase space barriers and dividing surfaces in the absence of critical points of the potential energy
Ezra, Gregory S
2010-01-01
We consider the existence of invariant manifolds in phase space governing reaction dynamics in situations where there are no saddle points on the potential energy surface in the relevant regions of configuration space. We point out that such situations occur in a number of important classes of chemical reactions, and we illustrate this concretely by considering a model for transition state switching in an ion-molecule association reaction due to Chesnavich (J. Chem. Phys. {\\bf 84}, 2615 (1986)). For this model we show that, in the region of configuration space relevant to the reaction, there are no saddle points on the potential energy surface, but that in phase space there is a normally hyperbolic invariant manifold (NHIM) bounding a dividing surface having the property that the reactive flux through this dividing surface is a minimum. We then describe two methods for finding NHIMs and their associated phase space structures in systems with more than two degrees-of-freedom. These methods do not rely on the e...
Nanoscale surface potential imaging of the photocatalytic TiO_{2} ﬁlms on aluminum
DEFF Research Database (Denmark)
Daviðsdóttir, Svava; Dirscherl, Kai; Canulescu, Stela
2013-01-01
The change in the surface potential of TiO2 coatings upon UV-illumination was investigated on the nanoscale using Scanning Kelvin Probe Force microscopy and on the micro-scale using photo-electrochemical measurements. A good correlation between the two techniques was obtained. The changes...... in the surface potential of TiO2 coatings upon UV-illumination are closely correlated to the band gap and thickness of the coatings. The inhomogeneity surface potential distribution of a 100 nm TiO2 film indicates a heterogeneous coating. Transition to a homogeneous surface potential distribution was observed...... with increasing thickness of the TiO2 coating....
An explicit surface-potential-based MOSFET model incorporating the quantum mechanical effects
Basu, Dipanjan; Dutta, Aloke K.
2006-07-01
An explicit surface-potential-based MOSFET model has been proposed in this work here, which takes into account the quantum mechanical effects that arise in deep-submicron MOSFETs. The coupled Schrödinger's and Poisson's equations have been solved by using a variational wave function approach, as proposed by Fang and Howard. The resulting surface potential model is analytical, technology mapped, and completely continuous over the entire range of operation. The surface potential and the inversion charge density calculated using the proposed model show good match with the results of the numerical simulations obtained from a self-consistent Schrödinger-Poisson solver for a wide range of substrate doping and oxide thickness. The simulated values of the drain current match closely with the experimental results published elsewhere. The device small-signal parameters, e.g., transconductance, output conductance, etc., pass the standard benchmark tests suggested by Suyama and Tsividis qualitatively, thereby validating the approach of the model presented.
Barghouty, A. F.; Adams, J. H., Jr.; Meyer, F.; Reinhold, c.
2010-01-01
Solar-wind induced sputtering of the lunar surface includes, in principle, both kinetic and potential sputtering. The role of the latter mechanism, however, in many focused studies has not been properly ascertained due partly to lack of data but can also be attributed to the assertion that the contribution of solar-wind heavy ions to the total sputtering is quite low due to their low number density compared to solar-wind protons. Limited laboratory measurements show marked enhancements in the sputter yields of slow-moving, highly-charged ions impacting oxides. Lunar surface sputtering yields are important as they affect, e.g., estimates of the compositional changes in the lunar surface, its erosion rate, as well as its contribution to the exosphere as well as estimates of hydrogen and water contents. Since the typical range of solar-wind ions at 1 keV/amu is comparable to the thickness of the amorphous rim found on lunar soil grains, i.e. few 10s nm, lunar simulant samples JSC-1A AGGL are specifically enhanced to have such rims in addition to the other known characteristics of the actual lunar soil particles. However, most, if not all laboratory studies of potential sputtering were carried out in single crystal targets, quite different from the rim s amorphous structure. The effect of this structural difference on the extent of potential sputtering has not, to our knowledge, been investigated to date.
A general potential for molecular dynamics of ion-sputtered surfaces
Akande, Raphael O
2015-01-01
Erosion of surface atoms of solid materials by ion bombardment (surface-sputtering) causes nano-ripples and quantum dots to self-organise on the surfaces. The self-organisation had been shown, in some sputtering experiments, to be influenced by unexpected contaminants (ions) from vacuum walls. Existing inter-atomic-interaction potentials of Molecular Dynamics (MD) simulations for studying this are unsuitable because they assume two-particle collisions at a time instead of many (including contaminants)-particle collisions (Wider-area Perturbations, (WP)). We designed this study to develop a suitable potential that incorporates WP of the MD. We developed the general potential to account for the possibility of WP due to contaminants (both foreign and local to the material) consequently shifting the eqiulibrium points of the MD the material. For instance, dynamics of Au and Fe were studied with O bombardments/contamination (oxygenated environments), and those of CSiGe were studied with W, Ti, and O. It was found ...
Excited State Potential Energy Surfaces of Polyenes and Protonated Schiff Bases.
Send, Robert; Sundholm, Dage; Johansson, Mikael P; Pawłowski, Filip
2009-09-08
The potential energy surface of the (1)Bu and (1)A' states of all-trans-polyenes and the corresponding protonated Schiff bases have been studied at density functional theory and coupled cluster levels. Linear polyenes and protonated Schiff bases with 4 to 12 heavy atoms have been investigated. The calculations show remarkable differences in the excited state potential energy surfaces of the polyenes and the protonated Schiff bases. The excited states of the polyenes exhibit high torsion barriers for single-bond twists and low torsion barriers for double-bond twists. The protonated Schiff bases, on the other hand, are very flexible molecules in the first excited state with low or vanishing torsion barriers for both single and double bonds. Calculations at density functional theory and coupled cluster levels yield qualitatively similar potential energy surfaces. However, significant differences are found for some single-bond torsions in longer protonated Schiff bases, which indicate a flaw of the employed time-dependent density functional theory methods. The close agreement between the approximate second and third order coupled cluster levels indicates that for these systems calculations at second order coupled cluster level are useful in the validation of results based on time-dependent density functional theory.
Computed Potential Energy Surfaces and Minimum Energy Pathways for Chemical Reactions
Walch, Stephen P.; Langhoff, S. R. (Technical Monitor)
1994-01-01
Computed potential energy surfaces are often required for computation of such parameters as rate constants as a function of temperature, product branching ratios, and other detailed properties. For some dynamics methods, global potential energy surfaces are required. In this case, it is necessary to obtain the energy at a complete sampling of all the possible arrangements of the nuclei, which are energetically accessible, and then a fitting function must be obtained to interpolate between the computed points. In other cases, characterization of the stationary points and the reaction pathway connecting them is sufficient. These properties may be readily obtained using analytical derivative methods. We have found that computation of the stationary points/reaction pathways using CASSCF/derivative methods, followed by use of the internally contracted CI method to obtain accurate energetics, gives usefull results for a number of chemically important systems. The talk will focus on a number of applications including global potential energy surfaces, H + O2, H + N2, O(3p) + H2, and reaction pathways for complex reactions, including reactions leading to NO and soot formation in hydrocarbon combustion.
Takatsuka, Kazuo
2007-10-18
Classical trajectory study of nuclear motion on the Born-Oppenheimer potential energy surfaces is now one of the standard methods of chemical dynamics. In particular, this approach is inevitable in the studies of large molecular systems. However, as soon as more than a single potential energy surface is involved due to nonadiabatic coupling, such a naive application of classical mechanics loses its theoretical foundation. This is a classic and fundamental issue in the foundation of chemistry. To cope with this problem, we propose a generalization of classical mechanics that provides a path even in cases where multiple potential energy surfaces are involved in a single event and the Born-Oppenheimer approximation breaks down. This generalization is made by diagonalization of the matrix representation of nuclear forces in nonadiabatic dynamics, which is derived from a mixed quantum-classical representation of the electron-nucleus entangled Hamiltonian [Takatsuka, K. J. Chem. Phys. 2006, 124, 064111]. A manifestation of quantum fluctuation on a classical subsystem that directly contacts with a quantum subsystem is discussed. We also show that the Hamiltonian thus represented gives a theoretical foundation to examine the validity of the so-called semiclassical Ehrenfest theory (or mean-field theory) for electron quantum wavepacket dynamics, and indeed, it is pointed out that the electronic Hamiltonian to be used in this theory should be slightly modified.
Institute of Scientific and Technical Information of China (English)
ZHANG Kai; LIN Jianzhong; LI Huijun
2006-01-01
The mixing of samples in heterogeneous microchannels with a periodically stepwise surface potential was analyzed numerically using the control volume method. The equations describing the wall potential and external potential were solved first to get the distribution of wall potential and external potential, respectively, then the momentum equation was solved to get the developed flow field.Finally, the mass transport equation was solved to get the concentration field. The simulation results show that the distribution of samples at the inlet of the microchannel determines its theoretical value of concentration, therefore, the pattern of the distribution of samples at the inlet and its corresponding velocity can be changed to get the desirable concentration of solute. The heterogeneous wall potential almost has no effect on the mixing of samples in two-inlet microfluidic devices. For three-inlet microfluidic devices, the comprehensive ability of transportation and mixing has an optimization when the ratio of periodic length of wall potential to the height of the microchannel is about 4.88.The above conclusions are helpful to the optimization of the design of microfluidic devices.
Jin, Emma Yu; Nebel, Markus E
2016-02-01
Various tools used to predict the secondary structure for a given RNA sequence are based on dynamic programming used to compute a conformation of minimum free energy. For structures without pseudoknots, a worst-case runtime proportional to n3, with n being the length of the sequence, results since a table of dimension n2 has to be filled in while a single entry gives rise to a linear computational effort. However, it was recently observed that reformulating the corresponding dynamic programming recursion together with the bookkeeping of potential folding alternatives (a technique called sparsification) may reduce the runtime to n2 on average, assuming that nucleotides of distance d form a hydrogen bond (i..e., are paired) with probability b/d(c) for some constants b > 0, c > 1. The latter is called the polymer-zeta model and plays a crucial role in speeding up the above mentioned algorithm. In this paper we discuss the application of the polymer-zeta property for the analysis of sparsification, showing that it must be applied conditionally on first and last positions to pair. Afterwards, we will investigate the combinatorics of RNA secondary structures assuming that the corresponding conditional probabilities behave according to a polymer-zeta probability model. We show that even if some of the structural parameters exhibit an almost realistic behavior on average, the expected shape of a folding in that model must be assumed to highly differ from those observed in nature. More precisely, we prove our polymer-zeta model to be appropriate for mRNA molecules but to fail in connection with almost every other family of RNA. Those findings explain the huge speedup of the dynamic programming algorithm observed empirically by Wexler et al. when applying sparsification in connection with mRNA data.
Muto, Masaki; Nojima, Daisuke; Yue, Liang; Kanehara, Hideyuki; Naruse, Hideaki; Ujiro, Asuka; Yoshino, Tomoko; Matsunaga, Tadashi; Tanaka, Tsuyoshi
2017-03-01
Microalgae have been accepted as a promising feedstock for biodiesel production owing to their capability of converting solar energy into lipids through photosynthesis. However, the high capital and operating costs, and high energy consumption, are hampering commercialization of microalgal biodiesel. In this study, the surface-floating microalga, strain AVFF007 (tentatively identified as Botryosphaerella sudetica), which naturally forms a biofilm on surfaces, was characterized for use in biodiesel production. The biofilm could be conveniently harvested from the surface of the water by adsorbing onto a polyethylene film. The lipid productivity of strain AVFF007 was 46.3 mg/L/day, allowing direct comparison to lipid productivities of other microalgal species. The moisture content of the surface-floating biomass was 86.0 ± 1.2%, which was much lower than that of the biomass harvested using centrifugation. These results reveal the potential of this surface-floating microalgal species as a biodiesel producer, employing a novel biomass harvesting and dewatering strategy.
Institute of Scientific and Technical Information of China (English)
ZOU Jian-Wei; HU Gui-Xiang; JIANG Yong-Jun; ZENG Min; ZHUANG Shu-Lin; YU Qing-Sen
2005-01-01
Polychlorinated dibenzofurans (PCDFs) represent an important kind of serious pollutant. They are highly toxic and persistent in environment. In this paper, geometrical optimizations and subsequent calculations of electrostatic potentials (ESPs) on molecular surface have been performed for all 135 PCDF congeners at the HF/6-31G* level. The effects of substitution value and variation of substitution position upon the surface ESPs have been discussed. A series of statistic-based structural descriptors derived from the surface ESPs have been calculated. For some PCDF congeners, linear relationships between aryl hydrocarbon receptor (AhR) biding affinity and aryl hydrocarbon hydroxylase (AHH) induction potency as well as theoretical descriptors have been established by multiple linear regression method. It appears that the quantities derived from the surface ESPs,(V)s,min,(V)s,(V)+s,σ2+and Nvmin, together with the molecular surface area and the energy gap between HOMO and LUMO can be well used to express the quantitative structure-toxicity relationships of PCDFs.
Physico-chemical surface properties of microalgae.
Ozkan, Altan; Berberoglu, Halil
2013-12-01
This study reports a comprehensive set of experimentally measured physico-chemical surface properties of 12 different microalgae including fresh and seawater species of green algae, diatoms and cyanobacteria. The surface free energy and its components including the acid-base (AB), van der Waals (LW), electron donor/acceptor parameters were quantified based on contact angle measurements along with the Lifshitz-van der Waals acid-base approach using the probe liquid surface tension parameters proposed by van Oss et al. as well as by Della Volpe and Siboni. Moreover, the zeta and surface potentials of all species were determined using electrophoretic mobility measurements along with using Smoluchowski's model. Finally, the free energy of cohesion of the microalgae was also determined based on the calculated surface energy properties. The results showed that the electron donor parameter correlated well with the free energy of cohesion in all groups of microalgae. Moreover, species known to form colonies and exhibit benthic cultures had distinctly hydrophobic surfaces compared to microalgae prefering planktonic growth. These results indicate the importance of surface hydrophobicity for causing biofouiling or flocculation of cultures. Finally, the zeta potentials did not show a distinctive trend with the types of microalgae but the surface potentials were markedly larger for the salt water species. The reported methods and data are expected to provide critical information for researchers and technology developers concerned with cell to cell and cell to substrata interactions of microalgae in algal biomass cultivation and harvesting, biofouling of membranes and surfaces, as well as cell-surface interactions in photosynthetic microbial fuel cell technologies.
Cooper, P. D.; Cooper, J. F.; Sittler, E. C.; Burger, M. H.; Sturner, S. J.; Rymer, A. M.
2008-12-01
The active south polar surface of Enceladus is exposed to strong chemical processing by direct interaction with charged plasma and energetic particles in the local magnetospheric environment of this icy moon. Chemical oxidation activity is suggested by detection of H2O2 at the surface in this region and less directly by substantial presence of CO2, CO, and N2 in the plume gases. Molecular composition of the uppermost surface, including ejecta from plume activity, is radiolytically transformed mostly by penetrating energetic electrons with lesser effects from more depleted populations of energetic protons. The main sources of molecular plasma ions and E-ring dust grains in the magnetospheric environment are the cryovolcanic plume emissions from Enceladus. These molecular ions and the dust grains are chemically processed by magnetospheric interactions that further impact surface chemistry on return to Enceladus. For example, H2O neutrals dominating the emitted plume gas return to the surface mostly as H3O+ ions after magnetospheric processing. Surface oxidant loading is further increased by return of radiolytically processed ice grains from the E-ring. Plume frost deposition and micrometeoroid gardening protect some fraction of newly produced molecular species from destruction by further irradiation. The evident horizontal and vertical mobility of surface ices in the south polar region drive mixing of these processed materials into the moon interior with potential impacts on deep ice molecular chemistry and plume gas production. Similarly as suggested previously for Europa, the externally driven source of radiolytic oxidants could affect evolution of life in any subsurface liquid water environments of Enceladus.
The Importance of Zeta Potential Measurements & Role of Ionic Strength in Flocculation Processes
Stoll, Serge
2013-01-01
For efficient water clarification, flocculation is usually induced using positively charged polyelectrolytes such as synthetic polymers to rapidly separate the liquid phase from the solid one and obtain a clear filtrate. Generally, the use of polymeric flocculants over inorganic polyelectrolytes, such as poly-aluminum complexes, gives significant advantages when the water has a high concentration of suspended solids; the concentration of the polymeric flocculant is lower, the resulting sludge...
Moser, Jan
2009-01-01
t is proved in this paper that there is a fine correlation between the values of $|\\zeta(1/2+i\\varphi(t)/2)|^4$ and $|\\zeta(1/2+it)|^2$ which correspond to two segments with gigantic distance each from other. This new asymptotic formula cannot be obtained in known theories of Balasubramanian, Heath-Brown and Ivic.
de Oliveira-Filho, Antonio Gustavo S; Aoto, Yuri Alexandre; Ornellas, Fernando R
2009-02-19
This work reports a state-of-the-art theoretical characterization of four new sulfur-bromine species and five transition states on the [H, S(2), Br] potential energy surface. Our highest level theoretical approach employed the method coupled cluster singles and doubles with perturbative contributions of connected triples, CCSD(T), along with the series of correlation-consistent basis sets and with extrapolation to the complete basis set (CBS) limit in the optimization of the geometrical parameters and to quantify the energetic quantities. The structural and vibrational frequencies here reported are unique and represent the most accurate investigation to date of these species. The global minimum corresponds to a skewed structure HSSBr with a disulfide bond; this is followed by a pyramidal-like structure, SSHBr, 18.85 kcal/mol above the minimum. Much higher in energy, we found another skewed structure, HSBrS (50.29 kcal/mol), with one S-Br dative-type bond, and another pyramidal-like one, HBrSS (109.80 kcal/mol), with two S-Br dative-type bonds. The interconversion of HSSBr into SSHBr can occur via a transfer of either the hydrogen or the bromine atom but involves a very high barrier of about 43 kcal/mol. These molecules are potentially a new route of coupling the sulfur and bromine chemistry in the atmosphere, and conditions of high concentration of H(2)S like in volcanic eruptions might contribute to their formation. We note that HSSBr can act as a reservoir molecule for the reaction between the radicals HSS and Br. Also, an assessment of the methods DFT/B3LYP/CBS and MP2/CBS relative to CCSD(T)/CBS provides insights on the expected performance of these methods on the characterization of polysulfides and also of more complex systems containing disulfide bridges.
Variation in Surface Ionization Potentials of Pristine and Hydrated BiVO4.
Crespo-Otero, Rachel; Walsh, Aron
2015-06-18
Bismuth vanadate (BiVO4) is a promising material for photoelectrochemical water splitting and photocatalytic degradation of organic moieties. We evaluate the ionization potentials of the (010) surface termination of BiVO4 using first-principles simulations. The electron removal energy of the pristine termination (7.2 eV) validates recent experimental reports. The effect of water absorption on the ionization potentials is considered using static models as well as structures obtained from molecular dynamics simulations. Owing to the large molecular dipole of H2O, adsorption stabilizes the valence band edge (downward band bending), thereby increasing the ionization potentials. These results provide new understanding to the role of polar layers on complex oxide semiconductors, with importance for the design of efficient photoelectrodes for water splitting.
Large gaps between consecutive maxima of the Riemann zeta-function on the critical line
Saker, S H
2011-01-01
In this paper, we derive new lower bounds for the normalized distances between consecutive maxima of the Riemann zeta-function on the critical line subject to the truth of the Riemann hypothesis. The method of our proofs relies on a Sobolev type inequality of one dimension and an Opial type inequality with best possible constants.
A Central Limit Theorem for the Zeroes of the Zeta Function
Rodgers, Brad
2012-01-01
On the assumption of the Riemann hypothesis, we generalize a central limit theorem of Fujii regarding the number of zeroes of Riemann's Zeta function that lie in a mesoscopic interval. The result mirrors results of Soshnikov and others in random matrix theory.
"Armastuse retsepti" tippkokk Zeta Jones ei oska muna keeta / Triin Tael
Tael, Triin
2007-01-01
Scott Hicksi romantiline komöödiafilm "Armastuse retsept" ("No Reservations"), mille peaosas Walesist pärit näitlejanna Catherine Zeta Jones. Näitlejanna muljeid oma rolliks ettevalmistustest, mille hulka käis ka praktika pärisrestoranis
Preliminary X-ray crystallographic analysis of glutathione transferase zeta 1 (GSTZ1a-1a)
Energy Technology Data Exchange (ETDEWEB)
Boone, Christopher D.; Zhong, Guo; Smeltz, Marci; James, Margaret O., E-mail: mojames@ufl.edu; McKenna, Robert, E-mail: mojames@ufl.edu
2014-01-21
Crystals of glutathione transferase zeta 1 were grown and shown to diffract X-rays to 3.1 Å resolution. They belonged to space group P1, with unit-cell parameters a = 42.0, b = 49.6, c = 54.6 Å, α = 82.9, β = 69.9, γ = 73.4°.
Molecular characterization of zeta class glutathione S-transferases from Pinus brutia Ten.
Indian Academy of Sciences (India)
E. Oztetik; F. Kockar; M. Alper; M. Iscan
2015-09-01
Glutathione transferases (GSTs; EC 2.5.1.18) play important roles in stress tolerance and metabolic detoxification in plants. In higher plants, studies on GSTs have focussed largely on agricultural plants. There is restricted information about molecular characterization of GSTs in gymnosperms. To date, only tau class GST enzymes have been characterized from some pinus species. For the first time, the present study reports cloning and molecular characterization of two zeta class GST genes, namely PbGSTZ1 and PbGSTZ2 from Pinus brutia Ten., which is an economically important pine native to the eastern Mediterranean region and have to cope with several environmental stress conditions. The PbGSTZ1 gene was isolated from cDNA, whereas PbGSTZ2 was isolated from genomic DNA. Sequence analysis of PbGSTZ1 and PbGSTZ2 revealed the presence of an open reading frame of 226 amino acids with typical consensus sequences of the zeta class plant GSTs. Protein and secondary structure prediction analysis of two zeta class PbGSTZs have shared common features of other plant zeta class GSTs. Genomic clone, PbGSTZ2 gene, is unexpectedly intronless. Extensive sequence analysis of PbGSTZ2, with cDNA clone, PbGSTZ1, revealed 87% identity at nucleotide and 81% identity at amino acid levels with 41 amino acids differences suggesting that genomic PbGSTZ2 gene might be an allelic or a paralogue version of PbGSTZ1.
Broadway teatrites näeb Denzel Washingtoni ja Catherine Zeta-Jonesi / Andres Laasik
Laasik, Andres, 1960-2016
2010-01-01
New Yorgis välja antud Tony teatriauhinna pälvisid filminäitlejad Denzel Washington, Catherine Zeta-Jones ja Scarlett Johansson. Parim lavale naasnud näidend - "Piirdeaed", parim uus näidend - draama "Punane", mis räägib läti päritolu maalikunstnikust Mark Rothkost. Parim muusikal - "Memphis"
Measurable operators and the asymptotics of heat kernels and zeta functions
Carey, Alan
2012-01-01
In this note we answer some questions inspired by the introduction, by Alain Connes, of the notion of measurable operators using Dixmier traces. These questions concern the relationship of measurability to the asymptotics of $\\zeta-$functions and heat kernels. The answers have remained elusive for some 15 years.
Boundary Conditions for the Maintenance of Memory by PKM[zeta] in Neocortex
Shema, Reul; Hazvi, Shoshi; Sacktor, Todd C.; Dudai, Yadin
2009-01-01
We report here that ZIP, a selective inhibitor of the atypical protein kinase C isoform PKM[zeta], abolishes very long-term conditioned taste aversion (CTA) associations in the insular cortex of the behaving rat, at least 3 mo after encoding. The effect of ZIP is not replicated by a general serine/threonine protein kinase inhibitor that is…
Broadway teatrites näeb Denzel Washingtoni ja Catherine Zeta-Jonesi / Andres Laasik
Laasik, Andres, 1960-2016
2010-01-01
New Yorgis välja antud Tony teatriauhinna pälvisid filminäitlejad Denzel Washington, Catherine Zeta-Jones ja Scarlett Johansson. Parim lavale naasnud näidend - "Piirdeaed", parim uus näidend - draama "Punane", mis räägib läti päritolu maalikunstnikust Mark Rothkost. Parim muusikal - "Memphis"
Certain Subclasses of Analytic and Bi-Univalent Functions Involving Double Zeta Functions
Directory of Open Access Journals (Sweden)
Saibah Siregar
2012-01-01
Full Text Available In the present paper, we introduce two new subclasses of the functions class Σ of bi-univalent functions involving double zeta functions in the open unit disc U={z:zEC, |z|<1}. The estimates on the coefficients |a2| and |a3| for functions in these new subclasses of the function class Σ are obtained in our investigation.
Fractals of the Julia and Mandelbrot sets of the Riemann $zeta$ Function
Woon, S C
1998-01-01
Computations of the Julia and Mandelbrot sets of the Riemann zeta function and observations of their properties are made. In the appendix section, a corollary of Voronin's theorem is derived and a scale-invariant equation for the bounds in Goldbach conjecture is conjectured.
"Armastuse retsepti" tippkokk Zeta Jones ei oska muna keeta / Triin Tael
Tael, Triin
2007-01-01
Scott Hicksi romantiline komöödiafilm "Armastuse retsept" ("No Reservations"), mille peaosas Walesist pärit näitlejanna Catherine Zeta Jones. Näitlejanna muljeid oma rolliks ettevalmistustest, mille hulka käis ka praktika pärisrestoranis
Nano surface engineering of Mn 2 O 3 for potential light-harvesting application
Kar, Prasenjit
2015-01-01
Manganese oxides are well known applied materials including their use as efficient catalysts for various environmental applications. Multiple oxidation states and their change due to various experimental conditions are concluded to be responsible for their multifaceted functionality. Here we demonstrate that the interaction of a small organic ligand with one of the oxide varieties induces completely new optical properties and functionalities (photocatalysis). We have synthesized Mn2O3 microspheres via a hydrothermal route and characterized them using scanning electron microscopy (SEM), X-ray diffraction (XRD) and elemental mapping (EDAX). When the microspheres are allowed to interact with the biologically important small ligand citrate, nanometer-sized surface functionalized Mn2O3 (NPs) are formed. Raman and Fourier transformed infrared spectroscopy confirm the covalent attachment of the citrate ligand to the dangling bond of Mn at the material surface. While cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS) analysis confirm multiple surface charge states after the citrate functionalization of the Mn2O3 NPs, new optical properties of the surface engineered nanomaterials in terms of absorption and emission emerge consequently. The engineered material offers a novel photocatalytic functionality to the model water contaminant methylene blue (MB). The effect of doping other metal ions including Fe3+ and Cu2+ on the optical and catalytic properties is also investigated. In order to prepare a prototype for potential environmental application of water decontamination, we have synthesized and duly functionalized the material on the extended surface of a stainless steel metal mesh (size 2 cm × 1.5 cm, pore size 150 μm × 200 μm). We demonstrate that the functionalized mesh always works as a "physical" filter of suspended particulates. However, it works as a "chemical" filter (photocatalyst) for the potential water soluble contaminant (MB) in the presence
The electrical conductivity and surface conduction of consolidated rock cores.
Alkafeef, Saad F; Alajmi, Abdullah F
2007-05-15
A fully computerized high-pressure and high-temperature core holder device is simultaneously used to determine the electrical conductivity, zeta potential, and surface conductivity of consolidated rock cores in aqueous and nonaqueous systems. The total electrical conductivity of rock cores was determined by coupling streaming current and potential measurements. This shows that neglecting the surface conductivity Ksigma is crucial to converting the streaming potential into zeta potentials. It is observed that plots of the core total conductivity as a function of the electrolyte conductivity KL exhibit two behaviors. At low ionic strength, the core conductivity clearly depends on the contribution of surface conductivity behind the slip plane, whereas at higher ionic strength, the magnitude of the surface conductivity becomes negligible. The electrical conductivity of rock cores was found to be in good agreement with the O'Brien theory and the Briggs method. The contribution of the stagnant layer to the surface conductivity in nonaqueous systems has been shown to be significant. This shows that the stagnant layer displays significantly different behavior in different nonaqueous systems, depending on the core porosity and the double-layer overlap. The results indicate that the application of electrokinetics in petroleum reservoirs can provide important insights into reservoir fluid flow characterization.
First fully ab initio potential energy surface of methane with a spectroscopic accuracy
Nikitin, A. V.; Rey, M.; Tyuterev, Vl. G.
2016-09-01
Full 9-dimensional ab initio potential energy surfaces for the methane molecule are constructed using extended electronic structure coupled-cluster calculations with various series of basis sets following increasing X cardinal numbers: cc-pVXZ (X = 3, 4, 5, 6), aug-cc-ACVXZ (X = 3, 4, 5), and cc-pCVXZ-F12 (X = 3, 4). High-order dynamic electron correlations including triple and quadrupole excitations as well as relativistic and diagonal Born-Oppenheimer breakdown corrections were accounted for. Analytical potential functions are parametrized as non-polynomial expansions in internal coordinates in irreducible tensor representation. Vibrational energy levels are reported using global variational nuclear motion calculations with exact kinetic energy operator and a full account of the tetrahedral symmetry of CH4. Our best ab initio surface including above-mentioned contributions provides the rms (obs.-calc.) errors of less than 0.11 cm-1 for vibrational band centers below 4700 cm-1, and ˜0.3 cm-1 for all 229 assigned experimentally determined vibrational levels up to the Icosad range <7900 cm-1 without empirically adjusted parameters. These results improve the accuracy of ab initio methane vibrational predictions by more than an order of magnitude with respect to previous works. This is an unprecedented accuracy of first-principles calculations of a five-atomic molecule for such a large data set. New ab initio potential results in significantly better band center predictions even in comparison with best available empirically corrected potential energy surfaces. The issues related to the basis set extrapolation and an additivity of various corrections at this level of accuracy are discussed.
Energy Technology Data Exchange (ETDEWEB)
Lopez, Henrique Fioravanti Miguel
2009-08-15
This work presents the study and development of a processing power system that could be used in the connection of renewable energy sources to commercial power grid. The system consists of a ZETA converter associated with a bridge inverter operating at low frequency. The Zeta converter, operating in discontinuous conduction mode (DCM), plays the main role in this arrangement, producing a rectified sinusoidal current waveform synchronized with the electric grid. The function of the full-bridge inverter, connected in cascade with the Zeta converter, is to reverse every 180 deg the current generated by the Zeta converter. Initially it presents the analysis of the Zeta converter operating in DCM, as well as a design criterion. Following by the control strategy and the experimental results for the proposed system are presented and discussed. (author)
Random matrices, generalized zeta functions and self-similarity of zero distributions
Energy Technology Data Exchange (ETDEWEB)
Shanker, O [Bitfone Corporation, 32451 Golden Lantern Ste. 301, Laguna Niguel, CA 92677 (United States)
2006-11-10
There is growing evidence for a connection between random matrix theories used in physics and the theory of the Riemann zeta function and L-functions. The theory underlying the location of the zeros of these generalized zeta functions is one of the key unsolved problems. Physicists are interested because of the Hilbert-Polya conjecture, that the non-trivial zeros of the zeta function correspond to the eigenvalues of some positive operator. To complement the continuing theoretical work, it would be useful to study empirically the locations of the zeros by different methods. In this paper we use the rescaled range analysis to study the spacings between successive zeros of these functions. Over large ranges of the zeros the spacings have a Hurst exponent of about 0.095, using sample sizes of 10 000 zeros. This implies that the distribution has a high fractal dimension (1.9), and shows a lot of detailed structure. The distribution is of the anti-persistent fractional Brownian motion type, with a significant degree of anti-persistence. Thus, the high-order zeros of these functions show a remarkable self-similarity in their distribution, over fifteen orders of magnitude for the Riemann zeta function{exclamation_point} We find that the Hurst exponents for the random matrix theories show a different behaviour. A heuristic study of the effect of low-order primes seems to show that this effect is a promising candidate to explain the results that we observe in this study. We study the distribution of zeros for L-functions of conductors 3 and 4, and find that the distribution is similar to that of the Riemann zeta functions.
Li, Song; Zheng, Rui; Chen, Shan-Jun; Chen, Yan; Chen, Peng
2017-03-01
The intermolecular potential energy surfaces (PESs) of the ground electronic state for the Rg-BrCl (Rg = He, Ne, Ar, Kr, Xe) van der Waals complexes have been constructed by using the coupled-cluster method in combination with the augmented quadruple-zeta correlation-consistent basis sets supplemented with an additional set of bond functions. The features of the anisotropic PESs for these complexes are remarkably similar, which are characterized by three minima and two saddle points between them. The global minimum corresponds to a collinear Rg-Br-Cl configuration. Two local minima, correlate with an anti-linear Rg-Cl-Br geometry and a nearly T-shaped structure, can also be located on each PES. The quantum bound state calculations enable us to investigate intermolecular vibrational states and rotational energy levels of the complexes. The transition frequencies are predicted and are fitted to obtain their corresponding spectroscopic constants. In general, the periodic trends are observed for this complex family. Comparisons with available experimental data for the collinear isomer of Ar-BrCl demonstrate reliability of our theoretical predictions, and our results for the other two isomers of Ar-BrCl as well as for other members of the complex family are also anticipated to be trustable. Except for the collinear isomer of Ar-BrCl, the data presented in this paper would be beneficial to improve our knowledge for these experimentally unknown species.