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Sample records for spacer chain length

  1. Aggregation behavior and intermicellar interactions of cationic Gemini surfactants: Effects of alkyl chain, spacer lengths and temperature

    International Nuclear Information System (INIS)

    Hajy Alimohammadi, Marjan; Javadian, Soheila; Gharibi, Hussein; Tehrani-Bagha, Ali reza; Alavijeh, Mohammad Rashidi; Kakaei, Karim

    2012-01-01

    Graphical abstract: Highlights: → Enthalpy-entropy compensation relation was found between and for gemini surfactants. → The intermicellar interaction parameters are influenced with increasing the lengths of the tail and the spacer of gemini surfactants. → Increasing temperature decreases the intermicellar interaction parameters. → The changes in micellar surface charge density, and phase transition between spherical and rod geometries explain the data. - Abstract: The aggregation behavior of the cationic Gemini surfactants C m H 2m+1 N(CH 3 ) 2 (CH 2 ) S (CH 3 ) 2 N C m H 2m+1 ,2Br - with m = 12, 14 and s = 2, 4 were studied by performing surface tension, electrical conductivity, pulsed field gradient nuclear magnetic resonance (PFG-NMR), and cyclic voltammetry (CV) measurements over the temperature range 298 K to 323 K. The critical micelle concentration (CMC), surface excess (Γ max ), mean molecular surface area (A min ), degree of counter ion dissociation (α), and the thermodynamic parameters of micellization were determined from the surface tension and conductance data. An enthalpy-entropy compensation effect was observed and all the plots of enthalpy-entropy compensation exhibit excellent linearity. The micellar self-diffusion coefficients (D m ) and intermicellar interaction parameters (k d ) were obtained from the PFG-NMR and CV measurements. These results are discussed in terms of the intermicellar interactions, the effects of the chain and spacer lengths on the micellar surface charge density, and the phase transition between spherical and rod geometries. The intermicellar interaction parameters were found to decrease slightly with increasing temperature for 14-4-14, which suggests that the micellar surface charge density decreases with increasing temperature. The mean values of the hydrodynamic radius, R h , and the aggregation number, N agg , of the Gemini surfactants'm-4-m micelles were calculated from the micellar self-diffusion coefficient

  2. Identification of planorbids from Venezuela by polymerase chain reaction amplification and restriction fragment length polymorphism of internal transcriber spacer of the RNA ribosomal gene

    Directory of Open Access Journals (Sweden)

    Caldeira Roberta L

    2000-01-01

    Full Text Available Snails of the genus Biomphalaria from Venezuela were subjected to morphological assessment as well as polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP analysis. Morphological identification was carried out by comparison of characters of the shell and the male and female reproductive apparatus. The PCR-RFLP involved amplification of the internal spacer region ITS1 and ITS2 of the RNA ribosomal gene and subsequent digestion of this fragment by the restriction enzymes DdeI, MnlI, HaeIII and MspI. The planorbids were compared with snails of the same species and others reported from Venezuela and present in Brazil, Cuba and Mexico. All the enzymes showed a specific profile for each species, that of DdeI being the clearest. The snails were identified as B. glabrata, B. prona and B. kuhniana.

  3. Identification of Biomphalaria havanensis and Biomphalaria obstructa populations from Cuba using polymerase chain reaction and restriction fragment length polymorphism of the ribosomal RNA intergenic spacer

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    Teofânia HDA Vidigal

    2001-07-01

    Full Text Available In Cuba, several Biomphalaria species have been reported such as B. orbignyi, B. schrammi, B. helophila, B. havanensis and B. peregrina; only the latter three are considered as potential hosts of Schistosoma mansoni. The specific identification of Biomphalaria species is based on anatomical and morphological characters of genital organs and shells. The correct identification of these snails is complicated by the high variation in these characters, similarity among species and in some cases by the small size of the snails. In this paper, we reported the classical morphological identification, the use of PCR and RFLP analysis of the internal transcribed spacer region of the ribosomal RNA genes for molecular identification of seven snail populations from different localities in Cuba. Using morphological and molecular analysis, we showed that among the studied Cuban Biomphalaria populations only B. havanensis and B. obstructa species were found.

  4. In Silico Study of Spacer Arm Length Influence on Drug Vectorization by Fullerene C60

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    Haifa Khemir

    2015-01-01

    Full Text Available This work studies theoretically the effect of spacer arm lengths on the characteristics of a fullerene C60-based nanovector. The spacer arm is constituted of a carbon chain including a variable number of methylene groups (n = 2–11. To improve the ability of the fullerene carriage, two arms are presented simultaneously through a malonyl bridge. Then the evolution of selected physicochemical parameters is monitored as a function of the spacer arm length and the angle between the two arms. We show here that while the studied characteristics are almost independent of the spacer arm length or vary monotonically with it, the dipole moment and its orientation vary periodically with the parity of the number of carbon atoms. This periodicity is related to both modules and orientations of dipole moments of the spacer arms. In the field of chemical synthesis, these results highlight the importance of theoretical calculations for the optimization of operating conditions. In the field of drug discovery, they show that theoretical calculations of the chemical properties of a drug candidate can help predict its in vivo behaviour, notably its bioavailability and biodistribution, which are known to be tightly dependent of its polarity.

  5. Exploring backbone-cation alkyl spacers for multi-cation side chain anion exchange membranes

    Science.gov (United States)

    Zhu, Liang; Yu, Xuedi; Hickner, Michael A.

    2018-01-01

    In order to systematically study how the arrangement of cations on the side chain and length of alkyl spacers between cations impact the performance of multi-cation AEMs for alkaline fuel cells, a series of polyphenylene oxide (PPO)-based AEMs with different cationic side chains were synthesized. This work resulted in samples with two or three cations in a side chain pendant to the PPO backbone. More importantly, the length of the spacer between cations varied from 3 methylene (-CH2-) (C3) groups to 8 methylene (C8) groups. The highest conductivity, up to 99 mS/cm in liquid water at room temperature, was observed for the triple-cation side chain AEM with pentyl (C5) or hexyl (C6) spacers. The multi-cation AEMs were found to have decreased water uptake and ionic conductivity when the spacer chains between cations were lengthened from pentyl (C5) or hexyl (C6) to octyl (C8) linking groups. The triple-cation membranes with pentyl (C5) or hexyl (C6) groups between cations showed greatest stability after immersion in 1 M NaOH at 80 °C for 500 h.

  6. Influence of spacer length on heparin coupling efficiency and fibrinogen adsorption of modified titanium surfaces

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    Gbureck Uwe

    2007-07-01

    Full Text Available Abstract Background Chemical bonding of the drug onto surfaces by means of spacer molecules is accompanied with a reduction of the biological activity of the drug due to a constricted mobility since normally only short spacer molecule like aminopropyltrimethoxysilane (APMS are used for drug coupling. This work aimed to study covalent attachment of heparin to titanium(oxide surfaces by varying the length of the silane coupling agent, which should affect the biological potency of the drug due to a higher mobility with longer spacer chains. Methods Covalent attachment of heparin to titanium metal and TiO2 powder was carried out using the coupling agents 3-(Trimethoxysilyl-propylamine (APMS, N- [3-(Trimethoxysilylpropyl]ethylenediamine (Diamino-APMS and N1- [3-(Trimethoxy-silyl-propyl]diethylenetriamine (Triamino-APMS. The amount of bound coupling agent and heparin was quantified photometrically by the ninhydrin reaction and the tolidine-blue test. The biological potency of heparin was determined photometrically by the chromogenic substrate Chromozym TH and fibrinogen adsorption to the modified surfaces was researched using the QCM-D (Quartz Crystal Microbalance with Dissipation Monitoring technique. Results Zeta-potential measurements confirmed the successful coupling reaction; the potential of the unmodified anatase surface (approx. -26 mV shifted into the positive range (> + 40 mV after silanisation. Binding of heparin results in a strongly negatively charged surface with zeta-potentials of approx. -39 mV. The retaining biological activity of heparin was highest for the spacer molecule Triamino-APMS. QCM-D measurements showed a lower viscosity for adsorbed fibrinogen films on heparinised surfaces by means of Triamino-APMS. Conclusion The remaining activity of heparin was found to be highest for the covalent attachment with Triamino-APMS as coupling agent due to the long chain of this spacer molecule and therefore the highest mobility of the drug

  7. Spacer length impacts the efficacy of targeted docetaxel conjugates in prostate-specific membrane antigen expressing prostate cancer.

    Science.gov (United States)

    Peng, Zheng-Hong; Sima, Monika; Salama, Mohamed E; Kopečková, Pavla; Kopeček, Jindřich

    2013-12-01

    Combination of targeted delivery and controlled release is a powerful technique for cancer treatment. In this paper, we describe the design, synthesis, structure validation and biological properties of targeted and non-targeted N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-docetaxel conjugates. Docetaxel (DTX) was conjugated to HPMA copolymer via a tetrapeptide spacer (-GFLG-). 3-(1,3-dicarboxypropyl)-ureido]pentanedioic acid (DUPA) was used as the targeting moiety to actively deliver DTX for treatment of Prostate-Specific Membrane Antigen (PSMA) expressing prostate cancer. Short and long spacer DUPA monomers were prepared, and four HPMA copolymer--DTX conjugates (non-targeted, two targeted with short spacer of different molecular weight and targeted with long spacer) were prepared via Reversible Addition-Fragmentation Chain Transfer (RAFT) copolymerization. Following confirmation of PSMA expression on C4-2 cell line, the DTX conjugates' in vitro cytotoxicity was tested against C4-2 tumor cells and their anticancer efficacies were assessed in nude mice bearing s.c. human prostate adenocarcinoma C4-2 xenografts. The in vivo results show that the spacer length between targeting moieties and HPMA copolymer backbone can significantly affect the treatment efficacy of DTX conjugates against C4-2 tumor bearing nu/nu mice. Moreover, histological analysis indicated that the DUPA-targeted DTX conjugate with longer spacer had no toxicity in major organs of treated mice.

  8. Effects of Polyethylene Glycol Spacer Length and Ligand Density on Folate Receptor Targeting of Liposomal Doxorubicin In Vitro

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    Kumi Kawano

    2011-01-01

    Full Text Available The folate receptor is an attractive target for selective tumor delivery of liposomal doxorubicin (DXR because it is abundantly expressed in a large percentage of tumors. This study examined the effect of polyethylene glycol (PEG spacer length and folate ligand density on the targeting ability of folate-modified liposomes. Liposomes were modified with folate-derivatized PEG-distearoylphosphatidylethanolamine with PEG molecular weights of 2000, 3400, or 5000. The association of DXR-loaded liposomes with KB cells, which overexpress the folate receptor, was evaluated by flow cytometry at various ratios of folate modification. A low ratio of folate modification with a sufficiently long PEG chain showed the highest folate receptor-mediated association with the cells, but did not show the highest in vitro cytotoxicity. DXR release from folate-modified liposomes in endosomes might be different. These findings will be useful for designing folate receptor-targeting carriers.

  9. Bolalipid fiber aggregation can be modulated by the introduction of sulfur atoms into the spacer chains.

    Science.gov (United States)

    Graf, Gesche; Drescher, Simon; Meister, Annette; Haramus, Vasyl M; Dobner, Bodo; Blume, Alfred

    2013-03-01

    The aggregation behavior in aqueous suspension of two symmetrical single-chain bolaamphiphiles, namely 12,21-dithiadotriacontane-1,32-diyl-bis [2-(tri-methylammonio)ethylphosphate] (PC-C32SS-PC) and 12,21-dithiadotriacontane-1,32-diyl-bis[2-(dimethylammonio)ethylphosphate] (Me(2)PE-C32SS-Me(2)PE), containing sulfur as heteroatoms in the chains, was studied using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), small angle neutron scattering (SANS), and transmission electron microscopy (TEM). The rheological properties of hydrogels formed by the aggregation into nanofibers were studied by oscillatory rheology. Based on the well-characterized behavior of bolalipids with long alkyl chains which at room temperature can form a network of nanofibers leading to the formation of a hydrogel, we investigated whether the incorporation of two heteroatoms of sulfur into the spacer chain of the molecules has an influence on the aggregation properties. Compared to the analogues without sulfur, the fibrous aggregates formed by sulfur containing compounds are less stable and build weaker viscoelastic gels. This is due to a perturbation of the packing of the chains as the sulfur atoms change the bond angle in the chain compared to the molecules with pure alkyl chains leading to kinks in the chain. For the bolaamphiphile with the Me(2)PE headgroups this effect is less pronounced due to the possibility of forming stabilizing hydrogen bonds between the headgroups. Copyright © 2012 Elsevier Inc. All rights reserved.

  10. Neutron chain length distributions in subcritical systems

    International Nuclear Information System (INIS)

    Nolen, S.D.; Spriggs, G.

    1999-01-01

    In this paper, the authors present the results of the chain-length distribution as a function of k in subcritical systems. These results were obtained from a point Monte Carlo code and a three-dimensional Monte Carlo code, MC++. Based on these results, they then attempt to explain why several of the common neutron noise techniques, such as the Rossi-α and Feynman's variance-to-mean techniques, are difficult to perform in highly subcritical systems using low-efficiency detectors

  11. Finite fission chain length and symmetry around prompt-criticality

    International Nuclear Information System (INIS)

    Xie Qilin; Yin Yanpeng; Gao Hui; Huang Po; Fang Xiaoqiang

    2012-01-01

    Probability distribution of finite fission chain length was derived by assuming that all neutrons behave identically. Finite fission chain length was also calculated using a zero-dimension Monte-Carlo method based on point kinetics. Then symmetry of finite fission chain length probability distribution around prompt-criticality was deduced, which helps understanding the emission rate of delayed neutrons and initiation of fission chain in super-prompt-critical system. (authors)

  12. Influence of the linking spacer length and type on the enantioseparation ability of β-cyclodextrin functionalized monoliths.

    Science.gov (United States)

    Guo, Jialiang; Xiao, Yuan; Lin, Yuanjing; Zhang, Qiaoxuan; Chang, Yiqun; Crommen, Jacques; Jiang, Zhengjin

    2016-05-15

    In order to investigate the effect of the linking spacer on the enantioseparation ability of β-cyclodextrin (β-CD) functionalized polymeric monoliths, three β-CD-functionalized organic polymeric monoliths with different spacer lengths were prepared by using three amino-β-CDs, i.e. mono-6-amino-6-deoxy-β-CD, mono-6-ethylenediamine-6-deoxy-β-CD, mono-6-hexamethylenediamine-6-deoxy-β-CD, as starting materials. These amino-β-CDs reacted with glycidyl methacrylate to produce functional monomers which were then copolymerized with ethylene dimethacrylate. The enantioseparation ability of the three monoliths was evaluated using 14 chiral acidic compounds, including mandelic acid derivatives, nonsteroidal anti-inflammatory drugs, N-derivatized amino acids, and chiral herbicides under optimum chromatographic conditions. Notably, the poly(GMA-NH2-β-CD-co-EDMA) column provides higher enantioresolution and enantioselectivity than the poly(GMA-EDA-β-CD-co-EDMA) and poly(GMA-HDA-β-CD-co-EDMA) columns for most tested chiral analytes. Furthermore, the enantioseparation performance of triazole-linker containing monoliths was compared to that of ethylenediamine-linker containing monoliths. The results indicate that the enantioselectivity of β-CD monolithic columns is strongly related to the length and type of spacer tethering β-CD to the polymeric support. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Constraints on food chain length arising from regional metacommunity dynamics

    Science.gov (United States)

    Calcagno, Vincent; Massol, François; Mouquet, Nicolas; Jarne, Philippe; David, Patrice

    2011-01-01

    Classical ecological theory has proposed several determinants of food chain length, but the role of metacommunity dynamics has not yet been fully considered. By modelling patchy predator–prey metacommunities with extinction–colonization dynamics, we identify two distinct constraints on food chain length. First, finite colonization rates limit predator occupancy to a subset of prey-occupied sites. Second, intrinsic extinction rates accumulate along trophic chains. We show how both processes concur to decrease maximal and average food chain length in metacommunities. This decrease is mitigated if predators track their prey during colonization (habitat selection) and can be reinforced by top-down control of prey vital rates (especially extinction). Moreover, top-down control of colonization and habitat selection can interact to produce a counterintuitive positive relationship between perturbation rate and food chain length. Our results show how novel limits to food chain length emerge in spatially structured communities. We discuss the connections between these constraints and the ones commonly discussed, and suggest ways to test for metacommunity effects in food webs. PMID:21367786

  14. Effect of Amphiphilic Alkyl Chain Length Upon Purified LATEX Stability

    International Nuclear Information System (INIS)

    Amira Amir Hassan; Amir Hashim Mohd Yatim

    2015-01-01

    Rubber particles in purified latex (PL) are stabilized by a film of protein and fatty acid soap (surfactant). Saturated straight-chain fatty acid soaps can assist an enhancement of latex stability. However, whether the alkyl chain length plays an important role in increasing the stability is still an issue. The aim of this study is to investigate the effect of alkyl chain length of anionic surfactant on the stability of purified latex. The fatty acid soap of decanoate (9), laurate (11), sodium dodecyl sulphate (SDS) (12) and palmitate (15) were used. The numbers in parentheses indicating the number of carbon present in alkyl chain of the soap. The results showed that the impact of alkyl chain length on the stability of latex is in the order of laurate > decanoate > SDS > palmitate > purified latex accordingly. The alkyl chain length does giving a significant effect on latex stability after longer stirring time. The particle size of latex with the presence of surfactant is greater compare to a single particle itself due to extension of particles diameter. Thus suitable interaction of the nonpolar tail of surfactant with the hydrophobic regions of latex surface played a major role in maintaining a stable latex system. (author)

  15. Characterization of Biomphalaria orbignyi, Biomphalaria peregrina and Biomphalaria oligoza by polymerase chain reaction and restriction enzyme digestion of the internal transcribed spacer region of the RNA ribosomal gene

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    Spatz Linus

    2000-01-01

    Full Text Available The correct identification of Biomphalaria oligoza, B. orbignyi and B. peregrina species is difficult due to the morphological similarities among them. B. peregrina is widely distributed in South America and is considered a potential intermediate host of Schistosoma mansoni. We have reported the use of the polymerase chain reaction and restriction fragment length polymorphism analysis of the internal transcribed spacer region of the ribosomal DNA for the molecular identification of these snails. The snails were obtained from different localities of Argentina, Brazil and Uruguay. The restriction patterns obtained with MvaI enzyme presented the best profile to identify the three species. The profiles obtained with all enzymes were used to estimate genetic similarities among B. oligoza, B. peregrina and B. orbignyi. This is also the first report of B. orbignyi in Uruguay.

  16. The Chain-Length Distribution in Subcritical Systems

    International Nuclear Information System (INIS)

    Nolen, Steven Douglas

    2000-01-01

    The individual fission chains that appear in any neutron multiplying system provide a means, via neutron noise analysis, to unlock a wealth of information regarding the nature of the system. This work begins by determining the probability density distributions for fission chain lengths in zero-dimensional systems over a range of prompt neutron multiplication constant (K) values. This section is followed by showing how the integral representation of the chain-length distribution can be used to obtain an estimate of the system's subcritical prompt multiplication (MP). The lifetime of the chains is then used to provide a basis for determining whether a neutron noise analysis will be successful in assessing the neutron multiplication constant, k, of the system in the presence of a strong intrinsic source. A Monte Carlo transport code, MC++, is used to model the evolution of the individual fission chains and to determine how they are influenced by spatial effects. The dissertation concludes by demonstrating how experimental validation of certain global system parameters by neutron noise analysis may be precluded in situations in which the system K is relatively low and in which realistic detector efficiencies are simulated

  17. The Chain-Length Distribution in Subcritical Systems

    Energy Technology Data Exchange (ETDEWEB)

    Nolen, Steven Douglas [Texas A & M Univ., College Station, TX (United States)

    2000-06-01

    The individual fission chains that appear in any neutron multiplying system provide a means, via neutron noise analysis, to unlock a wealth of information regarding the nature of the system. This work begins by determining the probability density distributions for fission chain lengths in zero-dimensional systems over a range of prompt neutron multiplication constant (K) values. This section is followed by showing how the integral representation of the chain-length distribution can be used to obtain an estimate of the system's subcritical prompt multiplication (MP). The lifetime of the chains is then used to provide a basis for determining whether a neutron noise analysis will be successful in assessing the neutron multiplication constant, k, of the system in the presence of a strong intrinsic source. A Monte Carlo transport code, MC++, is used to model the evolution of the individual fission chains and to determine how they are influenced by spatial effects. The dissertation concludes by demonstrating how experimental validation of certain global system parameters by neutron noise analysis may be precluded in situations in which the system K is relatively low and in which realistic detector efficiencies are simulated.

  18. Stochastic Simulation of a Full-Chain Reptation Model with Constraint Release, Chain-Length Fluctuations and Chain Stretching

    DEFF Research Database (Denmark)

    Neergaard, Jesper; Schieber, Jay D.

    1999-01-01

    A self-consistent reptation model that includes chain stretching, chain-length fluctuations, segment connectivity and constraint release is used to predict transient and steady flows. Quantitative comparisons are made with entangledsolution data. The model is able to capture quantitatively all...

  19. Expected value of finite fission chain lengths of pulse reactors

    International Nuclear Information System (INIS)

    Liu Jianjun; Zhou Zhigao; Zhang Ben'ai

    2007-01-01

    The average neutron population necessary for sponsoring a persistent fission chain in a multiplying system, is discussed. In the point reactor model, the probability function θ(n, t 0 , t) of a source neutron at time t 0 leading to n neutrons at time t is dealt with. The non-linear partial differential equation for the probability generating function G(z; t 0 , t) is derived. By solving the equation, we have obtained an approximate analytic solution for a slightly prompt supercritical system. For the pulse reactor Godiva-II, the mean value of finite fission chain lengths is estimated in this work and shows that the estimated value is reasonable for the experimental analysis. (authors)

  20. Glycogen with short average chain length enhances bacterial durability

    Science.gov (United States)

    Wang, Liang; Wise, Michael J.

    2011-09-01

    Glycogen is conventionally viewed as an energy reserve that can be rapidly mobilized for ATP production in higher organisms. However, several studies have noted that glycogen with short average chain length in some bacteria is degraded very slowly. In addition, slow utilization of glycogen is correlated with bacterial viability, that is, the slower the glycogen breakdown rate, the longer the bacterial survival time in the external environment under starvation conditions. We call that a durable energy storage mechanism (DESM). In this review, evidence from microbiology, biochemistry, and molecular biology will be assembled to support the hypothesis of glycogen as a durable energy storage compound. One method for testing the DESM hypothesis is proposed.

  1. Impact of underlap spacer region variation on electrostatic and analog performance of symmetrical high-k SOI FinFET at 20 nm channel length

    Science.gov (United States)

    Jain, Neeraj; Raj, Balwinder

    2017-12-01

    Continued scaling of CMOS technology to achieve high performance and low power consumption of semiconductor devices in the complex integrated circuits faces the degradation in terms of electrostatic integrity, short channel effects (SCEs), leakage currents, device variability and reliability etc. Nowadays, multigate structure has become the promising candidate to overcome these problems. SOI FinFET is one of the best multigate structures that has gained importance in all electronic design automation (EDA) industries due to its improved short channel effects (SCEs), because of its more effective gate-controlling capabilities. In this paper, our aim is to explore the sensitivity of underlap spacer region variation on the performance of SOI FinFET at 20 nm channel length. Electric field modulation is analyzed with spacer length variation and electrostatic performance is evaluated in terms of performance parameter like electron mobility, electric field, electric potential, sub-threshold slope (SS), ON current (I on), OFF current (I off) and I on/I off ratio. The potential benefits of SOI FinFET at drain-to-source voltage, V DS = 0.05 V and V DS = 0.7 V towards analog and RF design is also evaluated in terms of intrinsic gain (A V), output conductance (g d), trans-conductance (g m), gate capacitance (C gg), and cut-off frequency (f T = g m/2πC gg) with spacer region variations.

  2. Topological analysis of polymeric melts: chain-length effects and fast-converging estimators for entanglement length.

    Science.gov (United States)

    Hoy, Robert S; Foteinopoulou, Katerina; Kröger, Martin

    2009-09-01

    Primitive path analyses of entanglements are performed over a wide range of chain lengths for both bead spring and atomistic polyethylene polymer melts. Estimators for the entanglement length N_{e} which operate on results for a single chain length N are shown to produce systematic O(1/N) errors. The mathematical roots of these errors are identified as (a) treating chain ends as entanglements and (b) neglecting non-Gaussian corrections to chain and primitive path dimensions. The prefactors for the O(1/N) errors may be large; in general their magnitude depends both on the polymer model and the method used to obtain primitive paths. We propose, derive, and test new estimators which eliminate these systematic errors using information obtainable from the variation in entanglement characteristics with chain length. The new estimators produce accurate results for N_{e} from marginally entangled systems. Formulas based on direct enumeration of entanglements appear to converge faster and are simpler to apply.

  3. Effect of temperature on atom-atom collision chain length in metals

    International Nuclear Information System (INIS)

    Makarov, A.A.; Demkin, N.A.; Lyashchenko, B.G.

    1981-01-01

    Focused atom-atom collision chain lengths are calculated for fcc-crystals with account of thermal oscillations. The model of solid spheres with the Born-Merier potential has been used in the calculations. The dependence of chain lengths on the temperature, energy and movement direction of the first chain atom for Cu, Au, Ag, Pb, Ni is considered. The plot presented shows that the chain lengths strongly decrease with temperature growth, for example, for the gold at T=100 K the chain length equals up to 37 interatomic spacings, whereas at T=1000 K their length decreases down to 5 interatomic distances. The dependence of the energy loss by the chain atoms on the atom number in the chain is obtained in a wide range of crystal temperature and the primary chain atom energy [ru

  4. Self-Assembly of Alkylammonium Chains on Montmorillonite: Effect of Interlayer Cations, CEC, and Chain Length

    Science.gov (United States)

    Chen, Hua; Li, Yingjun; Zhou, Yuanlin; Wang, Shanqiang; Zheng, Jian; He, Jiacai

    2017-12-01

    Recently, polymeric materials have been filled with synthetic or natural inorganic compounds in order to improve their properties. Especially, polymer clay nanocomposites have attracted both academic and industrial attention. Currently, the structure and physical phenomena of organoclays at molecular level are difficultly explained by existing experimental techniques. In this work, molecular dynamics (MD) simulation was executed using the CLAYFF and CHARMM force fields to evaluate the structural properties of organoclay such as basal spacing, interlayer density, energy and the arrangement of alkyl chains in the interlayer spacing. Our results are in good agreement with available experimental or other simulation data. The effects of interlayer cations (Na+, K+, Ca2+), the cation exchange capacity, and the alkyl chain length on the basal spacing and the structural properties are estimated. These simulations are expected to presage the microstructure of organo-montmorillonite and lead relevant engineering applications.

  5. The roles of productivity and ecosystem size in determining food chain length in tropical terrestrial ecosystems.

    Science.gov (United States)

    Young, Hillary S; McCauley, Douglas J; Dunbar, Robert B; Hutson, Michael S; Ter-Kuile, Ana Miller; Dirzo, Rodolfo

    2013-03-01

    Many different drivers, including productivity, ecosystem size, and disturbance, have been considered to explain natural variation in the length of food chains. Much remains unknown about the role of these various drivers in determining food chain length, and particularly about the mechanisms by which they may operate in terrestrial ecosystems, which have quite different ecological constraints than aquatic environments, where most food chain length studies have been thus far conducted. In this study, we tested the relative importance of ecosystem size and productivity in influencing food chain length in a terrestrial setting. We determined that (1) there is no effect of ecosystem size or productive space on food chain length; (2) rather, food chain length increases strongly and linearly with productivity; and (3) the observed changes in food chain length are likely achieved through a combination of changes in predator size, predator behavior, and consumer diversity along gradients in productivity. These results lend new insight into the mechanisms by which productivity can drive changes in food chain length, point to potential for systematic differences in the drivers of food web structure between terrestrial and aquatic systems, and challenge us to consider how ecological context may control the drivers that shape food chain length.

  6. Electroactive chain-like compounds constructed from trimetallic clusters and 4,4'-bipyridine spacers: one-pot synthesis, characterization and surface binding.

    Science.gov (United States)

    Abe, Masaaki; Inatomi, Atsushi; Hisaeda, Yoshio

    2011-03-14

    This paper reports the synthesis and characterization of a novel series of chain-like compounds where oxo-centered triruthenium cluster moieties are bridged by 4,4'-bipyridine (4,4'-bpy) spacers. A reaction of solvent-coordinated triruthenium "monomer" precursor [Ru(3)O(CH(3)CO(2))(6)(CO)(CH(3)OH)(2)] with a 0.1 equimolar amount of 4,4'-bpy in CH(3)OH gave mixture of chain-like compounds containing "dimers" to "tetramers" which were cleanly separated by column chromatography and characterized by spectroscopic and electrochemical methods. Cyclic voltammetry revealed that all chain-like compounds exhibit reversible and stepwise redox processes in solution with very weak intramolecular coupling between the triruthenium components across the 4,4'-bpy bridge. Photo-induced dissociation of CO from the compounds and electrode surface binding were also investigated.

  7. Identification of cultured isolates of clinically important yeast species using fluorescent fragment length analysis of the amplified internally transcribed rRNA spacer 2 region

    Directory of Open Access Journals (Sweden)

    Muylaert An

    2002-07-01

    Full Text Available Abstract Background The number of patients with yeast infection has increased during the last years. Also the variety of species of clinical importance has increased. Correct species identification is often important for efficient therapy, but is currently mostly based on phenotypic features and is sometimes time-consuming and depends largely on the expertise of technicians. Therefore, we evaluated the feasibility of PCR-based amplification of the internally transcribed spacer region 2 (ITS2, followed by fragment size analysis on the ABI Prism 310 for the identification of clinically important yeasts. Results A rapid DNA-extraction method, based on simple boiling-freezing was introduced. Of the 26 species tested, 22 could be identified unambiguously by scoring the length of the ITS2-region. No distinction could be made between the species Trichosporon asteroides and T. inkin or between T. mucoides and T. ovoides. The two varieties of Cryptococcus neoformans (var. neoformans and var. gattii could be differentiated from each other due to a one bp length difference of the ITS2 fragment. The three Cryptococcus laurentii isolates were split into two groups according to their ITS2-fragment lengths, in correspondence with the phylogenetic groups described previously. Since the obtained fragment lengths compare well to those described previously and could be exchanged between two laboratories, an internationally usable library of ITS2 fragment lengths can be constructed. Conclusions The existing ITS2 size based library enables identification of most of the clinically important yeast species within 6 hours starting from a single colony and can be easily updated when new species are described. Data can be exchanged between laboratories.

  8. Structure-guided investigation of lipopolysaccharide O-antigen chain length regulators reveals regions critical for modal length control.

    Science.gov (United States)

    Kalynych, Sergei; Ruan, Xiang; Valvano, Miguel A; Cygler, Miroslaw

    2011-08-01

    The O-antigen component of the lipopolysaccharide (LPS) represents a population of polysaccharide molecules with nonrandom (modal) chain length distribution. The number of the repeat O units in each individual O-antigen polymer depends on the Wzz chain length regulator, an inner membrane protein belonging to the polysaccharide copolymerase (PCP) family. Different Wzz proteins confer vastly different ranges of modal lengths (4 to >100 repeat units), despite having remarkably conserved structural folds. The molecular mechanism responsible for the selective preference for a certain number of O units is unknown. Guided by the three-dimensional structures of PCPs, we constructed a panel of chimeric molecules containing parts of two closely related Wzz proteins from Salmonella enterica and Shigella flexneri which confer different O-antigen chain length distributions. Analysis of the O-antigen length distribution imparted by each chimera revealed the region spanning amino acids 67 to 95 (region 67 to 95), region 200 to 255, and region 269 to 274 as primarily affecting the length distribution. We also showed that there is no synergy between these regions. In particular, region 269 to 274 also influenced chain length distribution mediated by two distantly related PCPs, WzzB and FepE. Furthermore, from the 3 regions uncovered in this study, region 269 to 274 appeared to be critical for the stability of the oligomeric form of Wzz, as determined by cross-linking experiments. Together, our data suggest that chain length determination depends on regions that likely contribute to stabilize a supramolecular complex.

  9. How Chain Length and Charge Affect Surfactant Denaturation of Acyl Coenzyme A Binding Protein (ACBP)

    DEFF Research Database (Denmark)

    Andersen, Kell Kleiner; Otzen, Daniel

    2009-01-01

    maltoside (DDM). The aim has been to determine how surfactant chain length and micellar charge affect the denaturation mechanism. ACBP denatures in two steps irrespective of surfactant chain length, but with increasing chain length, the potency of the denaturant rises more rapidly than the critical micelle......Using intrinsic tryptophan fluorescence, equilibria and kinetics of unfolding of acyl coenzyme A binding protein (ACBP) have been investigated in sodium alkyl sulfate surfactants of different chain length (8-16 carbon atoms) and with different proportions of the nonionic surfactant dodecyl...... constants increases linearly with denaturant concentration below the cmc but declines at higher concentrations. Both shortening chain length and decreasing micellar charge reduce the overall kinetics of unfolding and makes the dependence of unfolding rate constants on surfactant concentration more complex...

  10. Polyurethanes elastomers with amide chain extenders of uniform length

    NARCIS (Netherlands)

    van der Schuur, J.M.; Noordover, B.A.J.; Noordover, Bart; Gaymans, R.J.

    2006-01-01

    Toluene diisocyanate based polyurethanes with amide extenders were synthesized poly(propylene oxide) with a number average molecular weight of 2000 and endcapped with toluene diisocyanate was used as the polyether segment. The chain extenders were based on poly(hexamethylene terephthalamide):

  11. Polyuretehane elastomers with amide chain extenders of uniform length

    NARCIS (Netherlands)

    Schuur, van der M.; Noordover, B.A.J.; Gaymans, R.J.

    2006-01-01

    Toluene diisocyanate based polyurethanes with amide extenders were synthesized poly(propylene oxide) with a number average molecular weight of 2000 and endcapped with toluene diisocyanate was used as the polyether segment. The chain extenders were based on poly(hexamethylene terephthalamide):

  12. Quantum discord length is enhanced while entanglement length is not by introducing disorder in a spin chain.

    Science.gov (United States)

    Sadhukhan, Debasis; Roy, Sudipto Singha; Rakshit, Debraj; Prabhu, R; Sen De, Aditi; Sen, Ujjwal

    2016-01-01

    Classical correlation functions of ground states typically decay exponentially and polynomially, respectively, for gapped and gapless short-range quantum spin systems. In such systems, entanglement decays exponentially even at the quantum critical points. However, quantum discord, an information-theoretic quantum correlation measure, survives long lattice distances. We investigate the effects of quenched disorder on quantum correlation lengths of quenched averaged entanglement and quantum discord, in the anisotropic XY and XYZ spin glass and random field chains. We find that there is virtually neither reduction nor enhancement in entanglement length while quantum discord length increases significantly with the introduction of the quenched disorder.

  13. Synthesis and characterization of novel side-chain liquid crystalline polycarbonates, 4 - Synthesis of side-chain liquid crystalline polycarbonates with mesogenic groups having tails of different lengths

    NARCIS (Netherlands)

    Jansen, J.C.; Addink, R.; Nijenhuis, K.T.; Mijs, W.J.

    1999-01-01

    Side-chain liquid crystalline polycarbonates with alkoxyphenylbenzoate side groups, having a short spacer and tails ranging from 1 to 8 C-atoms, were synthesized. The polymers were prepared by an organo-zinc catalysed copolymerization of carbon dioxide and mesogenic 4-alkoxyphenyl

  14. Synthesis and characterization of novel side-chain liquid crystalline polycarbonates, 5 - Mesophase characterization of side-chain liquid crystalline polycarbonates with tails of different lengths

    NARCIS (Netherlands)

    Jansen, J.C.; Addink, R.; Nijenhuis, K.T.; Mijs, W.J.

    1999-01-01

    The mesomorphic properties and thermal stability of side-chain LC polycarbonates with alkoxyphenyl benzoate side groups having a short spacer and alkoxy tails ranging from 1 to 8 carbon atoms were studied by DSC, X-ray diffraction and polarized light optical microscopy. All polymers have a smectic A

  15. Fuel spacer

    International Nuclear Information System (INIS)

    Nishida, Koji; Yokomizo, Osamu; Kanazawa, Toru; Kashiwai, Shin-ichi; Orii, Akihito.

    1992-01-01

    The present invention concerns a fuel spacer for a fuel assembly of a BWR type reactor and a PTR type reactor. Springs each having a vane are disposed on the side surface of a circular cell which supports a fuel rods. A vortex streams having a vertical component are formed by the vanes in the flowing direction of a flowing channel between adjacent cylindrical cells. Liquid droplets carried by streams are deposited on liquid membrane streams flowing along the fuel rod at the downstream of the spacer by the vortex streams. In view of the above, the liquid droplets can be deposited to the fuel rod without increasing the amount of metal of the spacer. Accordingly, the thermal margin of the fuel assembly can be improved without losing neutron economy. (I.N.)

  16. Dependence of the product chain-length on detergents for long-chain E-polyprenyl diphosphate synthases

    Science.gov (United States)

    Pan, Jian-Jung; Ramamoorthy, Gurusankar; Poulter, C. Dale

    2013-01-01

    Long-chain E-polyprenyl diphosphate synthases (E-PDS) catalyze repetitive addition of isopentenyl diphosphate (IPP) to the growing prenyl chain of an allylic diphosphate. The polyprenyl diphosphate products are required for the biosynthesis of ubiquinones and menaquinones required for electron transport during oxidative phosphorylation to generate ATP. In vitro, the long-chain PDSs require addition of phospholipids or detergents to the assay buffer to enhance product release and maintain efficient turnover. During preliminary assays of product chain-length with anionic, zwitterionic, and non-ionic detergents, we discovered considerable variability. Examination of a series of non-ionic PEG detergents with several long-chain E-PDSs from different organisms revealed that in vitro incubations with nonaethylene glycol monododecyl ether or Triton X-100 typically gave chain lengths that corresponded to those of the isoprenoid moieties in respiratory quinones synthesized in vivo. In contrast incubations in buffer with n-butanol, CHAPS, DMSO, n-octyl-β-glucopyranoside, or β-cyclodextrin or in buffer without detergent typically proceeded more slowly and gave a broad range of chain lengths. PMID:23802587

  17. Side insertable spacer

    International Nuclear Information System (INIS)

    Patterson, J.F.; Ewing, R.H.

    1992-01-01

    This patent describes a spacer for restraining the fuel rods of a nuclear fuel assembly, the assembly being formed of a plurality of parallel, elongated fuel rods so arranged that the assembly is bounded by a polygon having an even number of sides, the rods being so arranged as to lie in a plurality of sets of parallel rows, the rows of each set being perpendicular to one of the sides of the polygon. It comprises a number of spacer combs equal to at least half the number of the sides of the polygon, the spacer combs being superposed on each other, each of the spacer combs comprising: a single base strip having a length equal to that of one of the sides of the polygon and grid strips equal in number to the spaces between rows in one of the sets, and at least a majority of the grid strips being of a length sufficient to extend substantially the full length of the rows; the grid strips being provided with spring members positioned to engage each of the rods; the grid strips being provided with spring members positioned to engage each of the rods; the grid strips being secured to and extending at right angles to the base strip; the grid strips of different combs being positioned at angles to each other, so as to occupy the spaces between rows in different sets

  18. Exploring the impact of the side-chain length on peptide/RNA binding events.

    Science.gov (United States)

    Sbicca, Lola; González, Alejandro López; Gresika, Alexandra; Di Giorgio, Audrey; Closa, Jordi Teixido; Tejedor, Roger Estrada; Andréola, Marie-Line; Azoulay, Stéphane; Patino, Nadia

    2017-07-19

    The impact of the amino-acid side-chain length on peptide-RNA binding events has been investigated using HIV-1 Tat derived peptides as ligands and the HIV-1 TAR RNA element as an RNA model. Our studies demonstrate that increasing the length of all peptide side-chains improves unexpectedly the binding affinity (K D ) but reduces the degree of compactness of the peptide-RNA complex. Overall, the side-chain length appears to modulate in an unpredictable way the ability of the peptide to compete with the cognate TAR RNA partner. Beyond the establishment of non-intuitive fundamental relationships, our results open up new perspectives in the design of effective RNA ligand competitors, since a large number of them have already been identified but few studies report on the modulation of the biological activity by modifying in the same way the length of all chains connecting RNA recognition motives to the central scaffold of a ligand.

  19. Novel odd/even effect of alkylene chain length on the photopolymerizability of organogelators.

    Science.gov (United States)

    Aoki, Ken'ichi; Kudo, Masabumi; Tamaoki, Nobuyuki

    2004-10-28

    [reaction: see text] Starting from diactylene diacarboxylic acids, we have synthesized a series of photopolymerizable organogelators that possess simple amide structures, different alkylene chain lengths, and either optically active or racemic 3,7-dimethyl-1-octylamine units. The alkylene chain length of these compounds exhibits a prominent odd/even effect with respect to the photopolymerization in the gel state and is accompanied by a stereostructural effect on the gelation ability.

  20. Distinguishing Heterodera filipjevi and H. avenae using polymerase chain reaction-restriction fragment length polymorphism and cyst morphology.

    Science.gov (United States)

    Yan, Guiping; Smiley, Richard W

    2010-03-01

    The cereal cyst nematodes Heterodera filipjevi and H. avenae impede wheat production in the Pacific Northwest (PNW). Accurate identification of cyst nematode species and awareness of high population density in affected fields are essential for designing effective control measures. Morphological methods for differentiating these species are laborious. These species were differentiated using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) of internal transcribed spacer (ITS)-ribosomal (r)DNA with up to six restriction endonucleases (TaqI, HinfI, PstI, HaeIII, RsaI, and AluI). The method was validated by inspecting underbridge structures of cyst vulval cones. Grid soil sampling of an Oregon field infested by both species revealed that H. filipjevi was present at most of the infested grid sites but mixtures of H. avenae and H. filipjevi also occurred. These procedures also detected and differentiated H. filipjevi and H. avenae in soil samples from nearby fields in Oregon and H. avenae in samples from Idaho and Washington. Intraspecific polymorphism was not observed within H. filipjevi or PNW H. avenae populations based on the ITS-rDNA. However, intraspecific variation was observed between H. avenae populations occurring in the PNW and France. Methods described here will improve detection and identification efficiencies for cereal cyst nematodes in wheat fields.

  1. Resonance chains in open systems, generalized zeta functions and clustering of the length spectrum

    International Nuclear Information System (INIS)

    Barkhofen, S; Faure, F; Weich, T

    2014-01-01

    In many non-integrable open systems in physics and mathematics, resonances have been found to be surprisingly ordered along curved lines in the complex plane. In this article we provide a unifying approach to these resonance chains by generalizing dynamical zeta functions. By means of a detailed numerical study we show that these generalized zeta functions explain the mechanism that creates the chains of quantum resonance and classical Ruelle resonances for three-disk systems as well as geometric resonances on Schottky surfaces. We also present a direct system-intrinsic definition of the continuous lines on which the resonances are strung together as a projection of an analytic variety. Additionally, this approach shows that the existence of resonance chains is directly related to a clustering of the classical length spectrum on multiples of a base length. Finally, this link is used to construct new examples where several different structures of resonance chains coexist. (paper)

  2. Effect of hydrocarbon chain length of aliphatic diluents on hydrodynamic properties of irradiated solutions of extractant

    International Nuclear Information System (INIS)

    Gumenyuk, V.E.; Pribush, A.G.; Egorov, G.F.

    1990-01-01

    To optimize the composition of n-paraffin mixtures with different molecular weight, used as a diluent (D) of extractant during extraction reprocessing of spent fuel, interrelation between D hydrocarbon chain length and change in hydrodynamic properties of extraction mixture on D basis depending on the dose has been considered. It is shown that the value of threshold dose loading (D crit ), at which a sharp change in hydrodynamic properties of tri-n-butyl phosphate solutions in D is observed, decreases with hydrocarbon chain length growth. Empiric ratio relating D crit value and the number of carbon atoms of D is obtained

  3. Knotting dynamics of DNA chains of different length confined in nanochannels

    International Nuclear Information System (INIS)

    Suma, Antonio; Micheletti, Cristian; Orlandini, Enzo

    2015-01-01

    Langevin dynamics simulations are used to characterize the typical mechanisms governing the spontaneous tying, untying and the dynamical evolution of knots in coarse-grained models of DNA chains confined in nanochannels. In particular we focus on how these mechanisms depend on the chain contour length, L c , at a fixed channel width D = 56 nm corresponding to the onset of the Odijk scaling regime where chain backfoldings and hence knots are disfavoured but not suppressed altogether. We find that the lifetime of knots grows significantly with L c , while that of unknots varies to a lesser extent. The underlying kinetic mechanisms are clarified by analysing the evolution of the knot position along the chain. At the considered confinement, in fact, knots are typically tied by local backfoldings of the chain termini where they are eventually untied after a stochastic motion along the chain. Consequently, the lifetime of unknots is mostly controlled by backfoldings events at the chain ends, which is largely independent of L c . The lifetime of knots, instead, increases significantly with L c because knots can, on average, travel farther along the chain before being untied. The observed interplay of knots and unknots lifetimes underpins the growth of the equilibrium knotting probability of longer and longer chains at fixed channel confinement. (paper)

  4. Direct observation of the edge spin structure and chain length dependence of a finite haldane chain by high field ESR measurements

    International Nuclear Information System (INIS)

    Yoshida, Makoto; Ohta, Hitoshi; Ito, Toshimitsu; Ajiro, Yoshitami

    2006-01-01

    We have performed high field and multi-frequency ESR measurements of finite length S=1 antiferromagnetic chains in Y 2 BaNi 0.96 Mg 0.04 O 5 . Owing to the high spectral resolution by high fields and high frequencies, observed ESR signals can be separated into the contributions of the finite chains with various chain lengths. Our results clearly show that the edge spins actually interact with each other through the quantum spin chain and the interaction depends on the chain length N. (author)

  5. Characterization of Binary Organogels Based on Some Azobenzene Compounds and Alkyloxybenzoic Acids with Different Chain Lengths

    Directory of Open Access Journals (Sweden)

    Yongmei Hu

    2014-01-01

    Full Text Available In this work the gelation behaviors of binary organogels composed of azobenzene amino derivatives and alkyloxybenzoic acids with different lengths of alkyl chains in various organic solvents were investigated and characterized. The corresponding gelation behaviors in 20 solvents were characterized and shown as new binary organic systems. It showed that the lengths of substituent alkyl chains in compounds have played an important role in the gelation formation of gelator mixtures in present tested organic solvents. Longer methylene chains in molecular skeletons in these gelators seem more suitable for the gelation of present solvents. Morphological characterization showed that these gelator molecules have the tendency to self-assemble into various aggregates from lamella, wrinkle, and belt to dot with change of solvents and gelator mixtures. Spectral characterization demonstrated different H-bond formation and hydrophobic force existing in gels, depending on different substituent chains in molecular skeletons. Meanwhile, these organogels can self-assemble to form monomolecular or multilayer nanostructures owing to the different lengths of due to alkyl substituent chains. Possible assembly modes for present xerogels were proposed. The present investigation is perspective to provide new clues for the design of new nanomaterials and functional textile materials with special microstructures.

  6. Phase behaviour of an ionic microemulsion system as a function of the cosurfactant chain length

    NARCIS (Netherlands)

    Kegel, W.K.; Lekkerkerker, H.N.W.

    1993-01-01

    The phase behaviour of a microemulsion system consisting of equal volumes of brine and oil, sodium dodecyl sulphate (SDS) as surfactant and alcohols of different chain lengths (pentanol, hexanol and heptanol) as cosurfactant was studied. In the case of pentanol, at low surfactant concentrations and

  7. Vaporization enthalpies of imidazolium based ionic liquids. A thermogravimetric study of the alkyl chain length dependence

    International Nuclear Information System (INIS)

    Verevkin, Sergey P.; Zaitsau, Dzmitry H.; Emel’yanenko, Vladimir N.; Ralys, Ricardas V.; Yermalayeu, Andrei V.; Schick, Christoph

    2012-01-01

    Highlights: ► Enthalpies of vaporization of ionic liquids were measured with thermogravimetry. ► We studied 1-alkyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide. ► The linear alkyl chain length was 4, 6, 8, 10, 12, 14, 16, and 18 C-atoms. ► A linear dependence on the chain length of the alkyl-imidazolium cation was found. - Abstract: Vaporization enthalpies for a series of ten ionic liquids (ILs) 1-alkyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide [C n mim][NTf 2 ], with the alkyl chain length n = 4, 6, 8, 10, 12, 14, 16, and 18 were determined using the thermogravimetric method. An internally consistent set of experimental data and vaporization enthalpies at 540 K was obtained. Vaporization enthalpies at 540 K have shown a linear dependence on the chain length of the alkyl-imidazolium cation in agreement with the experimental results measured previously with a quartz crystal microbalance. Ambiguity of Δ l g C pm o -values required for the extrapolation of experimental vaporization enthalpies to the reference temperature 298 K has been discussed.

  8. Biosynthesis of medium chain length alkanes for bio-aviation fuel by metabolic engineered Escherichia coli.

    Science.gov (United States)

    Wang, Meng; Nie, Kaili; Cao, Hao; Xu, Haijun; Fang, Yunming; Tan, Tianwei; Baeyens, Jan; Liu, Luo

    2017-09-01

    The aim of this work was to study the synthesis of medium-chain length alkanes (MCLA), as bio-aviation product. To control the chain length of alkanes and increase the production of MCLA, Escherichia coli cells were engineered by incorporating (i) a chain length specific thioesterase from Umbellularia californica (UC), (ii) a plant origin acyl carrier protein (ACP) gene and (iii) the whole fatty acid synthesis system (FASs) from Jatropha curcas (JC). The genetic combination was designed to control the product spectrum towards optimum MCLA. Decanoic, lauric and myristic acid were produced at concentrations of 0.011, 0.093 and 1.657mg/g, respectively. The concentration of final products nonane, undecane and tridecane were 0.00062mg/g, 0.0052mg/g, and 0.249mg/g respectively. Thioesterase from UC controlled the fatty acid chain length in a range of 10-14 carbons and the ACP gene with whole FASs from JC significantly increased the production of MCLA. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. The effect of chain length and lipid phase transitions on the selective permeability properties of liposomes

    NARCIS (Netherlands)

    Blok, M.C.; Neut-Kok, E.C.M. van der; Deenen, L.L.M. van; Gier, J. de

    1975-01-01

    This paper describes experiments showing the importance of the fatty acid chain length on the barrier properties of liposomal bilayers, prepared from saturated lecithins, under conditions of lateral phase separation. 1. 1.|Above the gel to liquid crystalline phase transition temperature,

  10. The importance of chain length for the polyphosphate enhancement of acidic potassium permanganate chemiluminescence.

    Science.gov (United States)

    Holland, Brendan J; Adcock, Jacqui L; Nesterenko, Pavel N; Peristyy, Anton; Stevenson, Paul G; Barnett, Neil W; Conlan, Xavier A; Francis, Paul S

    2014-09-09

    Sodium polyphosphate is commonly used to enhance chemiluminescence reactions with acidic potassium permanganate through a dual enhancement mechanism, but commercially available polyphosphates vary greatly in composition. We have examined the influence of polyphosphate composition and concentration on both the dual enhancement mechanism of chemiluminescence intensity and the stability of the reagent under analytically useful conditions. The average chain length (n) provides a convenient characterisation, but materials with similar values can exhibit markedly different distributions of phosphate oligomers. There is a minimum polyphosphate chain length (∼6) required for a large enhancement of the emission intensity, but no further advantage was obtained using polyphosphate materials with much longer average chain lengths. Providing there is a sufficient average chain length, the optimum concentration of polyphosphate is dependent on the analyte and in some cases, may be lower than the quantities previously used in routine detection. However, the concentration of polyphosphate should not be lowered in permanganate reagents that have been partially reduced to form high concentrations of the key manganese(III) co-reactant, as this intermediate needs to be stabilised to prevent formation of insoluble manganese(IV). Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Modification of eucalyptus pulp fiber using silane coupling agents with aliphatic side chains of different length

    Science.gov (United States)

    The objective of this work was to evaluate the effect of three silane coupling agents with different aliphatic chain lengths on the hydrophobicity of eucalyptus pulp fiber. The three silanes coupling agents used (isobutyltrimethoxysilane, methyltrimethoxysilane, and n-octyltriethoxysilane [OTES]) we...

  12. effect of side chain length on the stability and structural properties of 3

    African Journals Online (AJOL)

    Preferred Customer

    We report on the effect of the alkoxy chain length on the thermodynamic ... studied by Hartree-Fock (HF) and Density Functional Theory (DFT) methods. ..... with longer alkoxy substituents on the phenyl ring have lesser value of change in Gibbs ...

  13. Chain length distribution and kinetic characteristics of an enzymatically produced polymer

    NARCIS (Netherlands)

    Mulders, K.J.M.; Beeftink, H.H.

    2013-01-01

    Non-processive enzymatic polymerization leads to a distribution of polymer chain lengths. A polymerization model was developed to investigate the relation between the extent of this distribution on one hand, and the polymerization start conditions and reaction kinetics on the other hand. The model

  14. Characterization of amylose nanoparticles prepared via nanoprecipitation: Influence of chain length distribution.

    Science.gov (United States)

    Chang, Yanjiao; Yang, Jingde; Ren, Lili; Zhou, Jiang

    2018-08-15

    The influence of chain length distribution of amylose on size and structure of the amylose nanoparticles (ANPs) prepared through nanoprecipitation was investigated. Amylose with different chain length distributions was obtained by β-amylase treating amylose paste for different times and measured by size exclusion chromatography (SEC) and fluorophore-assisted carbohydrate electrophoresis (FACE). ANPs prepared via precipitation were characterized by using dynamic light scattering (DLS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Results showed that the β-amylase treatments led to decrease in chain length of amylose, and it was the most important factor affecting size of ANPs. When hydrolysis degree of amylose was 52.8%, mean size of ANPs decreased from 206.4 nm to 102.7 nm. All the ANPs displayed a V-type crystalline structure and the effect of amylose chain length on crystallinity of the precipitated ANPs was negligible in the investigated range. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. Photoluminescence decay lifetime measurements of hemicyanine derivatives of different alkyl chain lengths

    International Nuclear Information System (INIS)

    Shim, Taekyu; Lee, Myounghee; Kim, Sungho; Sung, Jaeho; Rhee, Bum Ku; Kim, Doseok; Kim, Hyunsung; Yoon, Kyung Byung

    2004-01-01

    The fluorescence upconversion setup for the detection of photoluminescence (PL) decay lifetime with subpicosecond time resolution was constructed, and the photoluminescence phenomena of several hemicyanine dyes with alkyl chains of different chain lengths tethered to the N atom of the pyridine moiety (HC-n, n=6, 15, 22) in methanol were investigated. The average decay lifetimes of the solutions determined from the measured data by multi-order exponential decay curve fitting were ∼27 ps at the PL peak wavelength. It was found that the PL decay properties did not depend on the alkyl chain length in the molecule, implying that the twist of the alkylpyridinium ring of the molecule is not possible as a nonfluorescing relaxation pathway. The time-dependent PL spectra constructed from the PL lifetime data showed the dynamic Stokes shift of ∼1000 cm -1

  16. Infinite coherence time of edge spins in finite-length chains

    Science.gov (United States)

    Maceira, Ivo A.; Mila, Frédéric

    2018-02-01

    Motivated by the recent observation that exponentially long coherence times can be achieved for edge spins in models with strong zero modes, we study the impact of level crossings in finite-length spin chains on the dynamics of the edge spins. Focusing on the X Y spin-1 /2 chain with a transverse or longitudinal magnetic field, two models relevant to understanding recent experimental results on cobalt adatoms, we show that the edge spins can remain coherent for an infinite time even for a finite-length chain if the magnetic field is tuned to a value at which there is a level crossing. Furthermore, we show that the edge spins remain coherent for any initial state for the integrable case of a transverse field because all states have level crossings at the same value of the field, while the coherence time is increasingly large for lower temperatures in the case of a longitudinal field, which is nonintegrable.

  17. Investigation on effect of methylene spacer in holographic grating formation in eosin containing polymethacrylates

    Energy Technology Data Exchange (ETDEWEB)

    Manickasundaram, S. [Department of Chemistry, Anna University, Sardar Vallabai Patel Road, Chennai 600025 (India); Kannan, P. [Department of Chemistry, Anna University, Sardar Vallabai Patel Road, Chennai 600025 (India)]. E-mail: pakannan@annauniv.edu; Deepa, S. [Centre for Laser Technology, Department of Physics, Anna University, Chennai 600025 (India); Palanisamy, P.K. [Centre for Laser Technology, Department of Physics, Anna University, Chennai 600025 (India)

    2007-01-15

    A new series of eosin dye based poly(alkyloxymethacrylate)s was synthesized with an even number of side-chain methylene spacers by a free radical addition polymerization method for holographic optical data storage applications. These polymers were characterized by UV, IR and {sup 1}H NMR spectroscopy. The glass transition temperature and thermal stability of the polymers were investigated by DSC and TGA, respectively. As the spacer length increases in the side-chain, Tg, Tm and thermal stability of the polymers decrease, while a reverse trend was observed with film forming ability of the polymers. The optical characterization of the polymers was investigated by forming holographic grating using an Argon ion laser. The grating diffraction efficiency was found to depend not only on the concentration of polymeric film but also on the spacer length of the polymers.

  18. Investigation on effect of methylene spacer in holographic grating formation in eosin containing polymethacrylates

    International Nuclear Information System (INIS)

    Manickasundaram, S.; Kannan, P.; Deepa, S.; Palanisamy, P.K.

    2007-01-01

    A new series of eosin dye based poly(alkyloxymethacrylate)s was synthesized with an even number of side-chain methylene spacers by a free radical addition polymerization method for holographic optical data storage applications. These polymers were characterized by UV, IR and 1 H NMR spectroscopy. The glass transition temperature and thermal stability of the polymers were investigated by DSC and TGA, respectively. As the spacer length increases in the side-chain, Tg, Tm and thermal stability of the polymers decrease, while a reverse trend was observed with film forming ability of the polymers. The optical characterization of the polymers was investigated by forming holographic grating using an Argon ion laser. The grating diffraction efficiency was found to depend not only on the concentration of polymeric film but also on the spacer length of the polymers

  19. PEGylation on mixed monolayer gold nanoparticles: Effect of grafting density, chain length, and surface curvature.

    Science.gov (United States)

    Lin, Jiaqi; Zhang, Heng; Morovati, Vahid; Dargazany, Roozbeh

    2017-10-15

    PEGylation on nanoparticles (NPs) is widely used to prevent aggregation and to mask NPs from the fast clearance system in the body. Understanding the molecular details of the PEG layer could facilitate rational design of PEGylated NPs that maximize their solubility and stealth ability without significantly compromising the targeting efficiency and cellular uptake. Here, we use molecular dynamics (MD) simulation to understand the structural and dynamic the PEG coating of mixed monolayer gold NPs. Specifically, we modeled gold NPs with PEG grafting densities ranging from 0-2.76chain/nm 2 , chain length with 0-10 PEG monomers, NP core diameter from 5nm to 500nm. It is found that the area accessed by individual PEG chains gradually transits from a "mushroom" to a "brush" conformation as NP surface curvature become flatter, whereas such a transition is not evident on small NPs when grafting density increases. It is shown that moderate grafting density (∼1.0chain/nm 2 ) and short chain length are sufficient enough to prevent NPs from aggregating in an aqueous medium. The effect of grafting density on solubility is also validated by dynamic light scattering measurements of PEGylated 5nm gold NPs. With respect to the shielding ability, simulations predict that increase either grafting density, chain length, or NP diameter will reduce the accessibility of the protected content to a certain size molecule. Interestingly, reducing NP surface curvature is estimated to be most effective in promoting shielding ability. For shielding against small molecules, increasing PEG grafting density is more effective than increasing chain length. A simple model that includes these three investigated parameters is developed based on the simulations to roughly estimate the shielding ability of the PEG layer with respect to molecules of different sizes. The findings can help expand our current understanding of the PEG layer and guide rational design of PEGylated gold NPs for a particular

  20. Liquid crystalline polymers IX Main chain thermotropic poly (azomethine – ethers containing thiazole moiety linked with polymethylene spacers

    Directory of Open Access Journals (Sweden)

    2007-04-01

    Full Text Available A new homologous series of thermally stable thermotropic liquid crystalline poly(azomethine-ethers based on thiazole moiety were synthesized by solution polycondensation of 4,4`-diformyl-α,ω-diphenoxyalkanes, I–IV or 4,4`-diformyl-2,2`-dimethoxy-α,ω-diphenoxyalkanes V–VIII with the new bis(2-aminothiazole monomer X. A model compound XI was synthesized from X with benzaldehyde and characterized by elemental and spectral analyses. The inherent viscosities of the resulting polymers were in the range 0.43–1.34 dI/g. All the poly(azomethine-ethers were insoluble in common organic solvents but dissolved completely in concentrated H2SO4 and formic acid. The mesomorphic properties of these polymers were studied as a function of the diphenoxyalkane space length. Their thermotropic liquid crystalline properties were examined by DSC and optical polarizing microscopy and demonstrated that the resulting polymers form nematic mesophases over wide temperature ranges. The thermogravimetric analyses of those polymers were evaluated by TGA and DSC measurements and correlated to their structural units. X-ray analysis showed that polymers having some degree of crystallinity in the region 2θ = 5–60°. In addition, the morphological properties of selected examples were tested by scanning electron microscopy.

  1. Optimization of the alkyl side chain length of fluorine-18-labeled 7α-alkyl-fluoroestradiol

    International Nuclear Information System (INIS)

    Okamoto, Mayumi; Shibayama, Hiromitsu; Naka, Kyosuke; Kitagawa, Yuya; Ishiwata, Kiichi; Shimizu, Isao; Toyohara, Jun

    2016-01-01

    Introduction: Several lines of evidence suggest that 7α-substituted estradiol derivatives bind to the estrogen receptor (ER). In line with this hypothesis, we designed and synthesized 18 F-labeled 7α-fluoroalkylestradiol (Cn-7α-[ 18 F]FES) derivatives as molecular probes for visualizing ERs. Previously, we successfully synthesized 7α-(3-[ 18 F]fluoropropyl)estradiol (C3-7α-[ 18 F]FES) and showed promising results for quantification of ER density in vivo, although extensive metabolism was observed in rodents. Therefore, optimization of the alkyl side chain length is needed to obtain suitable radioligands based on Cn-7α-substituted estradiol pharmacophores. Methods: We synthesized fluoromethyl (23; C1-7α-[ 18 F]FES) to fluorohexyl (26; C6-7α-[ 18 F]FES) derivatives, except fluoropropyl (C3-7α-[ 18 F]FES) and fluoropentyl derivatives (C5-7α-[ 18 F]FES), which have been previously synthesized. In vitro binding to the α-subtype (ERα) isoform of ERs and in vivo biodistribution studies in mature female mice were carried out. Results: The in vitro IC 50 value of Cn-7α-FES tended to gradually decrease depending on the alkyl side chain length. C1-7α-[ 18 F]FES (23) showed the highest uptake in ER-rich tissues such as the uterus. Uterus uptake also gradually decreased depending on the alkyl side chain length. As a result, in vivo uterus uptake reflected the in vitro ERα affinity of each compound. Bone uptake, which indicates de-fluorination, was marked in 7α-(2-[ 18 F]fluoroethyl)estradiol (C2-7α-[ 18 F]FES) (24) and 7α-(4-[ 18 F]fluorobutyl)estradiol (C4-7α-[ 18 F]FES) (25) derivatives. However, C1-7α-[ 18 F]FES (23) and C6-7α-[ 18 F]FES (26) showed limited uptake in bone. As a result, in vivo bone uptake (de-fluorination) showed a bell-shaped pattern, depending on the alkyl side chain length. C1-7α-[ 18 F]FES (23) showed the same levels of uptake in uterus and bone compared with those of 16α-[ 18 F]fluoro-17β-estradiol. Conclusions: The optimal alkyl

  2. Dependence of adenine isolation efficiency on the chain length evidenced using paramagnetic particles and voltammetry measurements

    Energy Technology Data Exchange (ETDEWEB)

    Huska, Dalibor [Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University of Agriculture and Forestry, Zemedelska 1, CZ-613 00 Brno (Czech Republic); Adam, Vojtech [Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University of Agriculture and Forestry, Zemedelska 1, CZ-613 00 Brno (Czech Republic); Department of Animal Nutrition and Forage Production, Faculty of Agronomy, Mendel University of Agriculture and Forestry, Zemedelska 1, CZ-613 00 Brno (Czech Republic); Trnkova, Libuse [Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5, CZ-625 00 Brno (Czech Republic); Kizek, Rene [Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University of Agriculture and Forestry, Zemedelska 1, CZ-613 00 Brno (Czech Republic)], E-mail: kizek@sci.muni.cz

    2009-05-15

    The main aim of this work was to study the dependence of oligoadenine isolation efficiency on the chain length by using paramagnetic particles covered by homo-deoxythymidines ((dT)25) with subsequent detection by adsorptive transfer technique coupled with square wave voltammetry. For this purpose, the oligonucleotides of the length A5, A10, A15, A20, A25, A30, A35, A40 and poly(A) in various concentrations were chosen. We determined that the isolation efficiency defined as 'isolated oligonucleotide concentration'/'given oligonucleotide concentration' was about 55% on average. Sequence A25 demonstrated the best binding onto microparticles surface.

  3. Dependence of adenine isolation efficiency on the chain length evidenced using paramagnetic particles and voltammetry measurements

    International Nuclear Information System (INIS)

    Huska, Dalibor; Adam, Vojtech; Trnkova, Libuse; Kizek, Rene

    2009-01-01

    The main aim of this work was to study the dependence of oligoadenine isolation efficiency on the chain length by using paramagnetic particles covered by homo-deoxythymidines ((dT)25) with subsequent detection by adsorptive transfer technique coupled with square wave voltammetry. For this purpose, the oligonucleotides of the length A5, A10, A15, A20, A25, A30, A35, A40 and poly(A) in various concentrations were chosen. We determined that the isolation efficiency defined as 'isolated oligonucleotide concentration'/'given oligonucleotide concentration' was about 55% on average. Sequence A25 demonstrated the best binding onto microparticles surface.

  4. Influence of the chain length on the biological behaviour of 131I fatty acids

    International Nuclear Information System (INIS)

    Riche, F.; Mathieu, J.P.; Comet, M.; Vidal, M.; Pernin, C.; Marti-Batlle, D.; Busquet, G.; Bardy, A.

    1983-01-01

    Saturated and acetylenic fatty acids labeled with 131 I in ω position, differing by their chain length (C8 to C20) and the number odd or even of their carbon atoms are injected in mice. The evolution of the activity in myocardium, blood, liver and kidney is measured until 10 minutes after injection. The myocardial activity increases with chain length from C8 to C16 then decreases for C18 and C20. The odd or even number of carbon atoms does not influence myocardial activity but in the liver, activity is inferior with the odd fatty acids. The presence of a triple bond accelerates the output of activity from the myocardium and these fatty acids are not well suited for the study of myocardial metabolism [fr

  5. Influence of the chain length on the biological behaviour of /sup 131/I fatty acids

    Energy Technology Data Exchange (ETDEWEB)

    Riche, F.; Mathieu, J.P.; Comet, M.; Vidal, M.; Pernin, C.; Marti-Batlle, D.; Busquet, G. (Universite de Grenoble, 38 (France)); Bardy, A. (C.E.A.-ORIS, 91 - Gif-sur-Yvette (France))

    1983-01-01

    Saturated and acetylenic fatty acids labeled with /sup 131/I in ..omega.. position, differing by their chain length (C8 to C20) and the number odd or even of their carbon atoms are injected in mice. The evolution of the activity in myocardium, blood, liver and kidney is measured until 10 minutes after injection. The myocardial activity increases with chain length from C8 to C16 then decreases for C18 and C20. The odd or even number of carbon atoms does not influence myocardial activity but in the liver, activity is inferior with the odd fatty acids. The presence of a triple bond accelerates the output of activity from the myocardium and these fatty acids are not well suited for the study of myocardial metabolism.

  6. Communication disruption of guava moth (Coscinoptycha improbana) using a pheromone analog based on chain length.

    Science.gov (United States)

    Suckling, D M; Dymock, J J; Park, K C; Wakelin, R H; Jamieson, L E

    2013-09-01

    The guava moth, Coscinoptycha improbana, an Australian species that infests fruit crops in commercial and home orchards, was first detected in New Zealand in 1997. A four-component pheromone blend was identified but is not yet commercially available. Using single sensillum recordings from male antennae, we established that the same olfactory receptor neurons responded to two guava moth sex pheromone components, (Z)-11-octadecen-8-one and (Z)-12-nonadecen-9-one, and to a chain length analog, (Z)-13-eicosen-10-one, the sex pheromone of the related peach fruit moth, Carposina sasakii. We then field tested whether this non-specificity of the olfactory neurons might enable disruption of sexual communication by the commercially available analog, using male catch to synthetic lures in traps in single-tree, nine-tree and 2-ha plots. A disruptive pheromone analog, based on chain length, is reported for the first time. Trap catches for guava moth were disrupted by three polyethylene tubing dispensers releasing the analog in single-tree plots (86% disruption of control catches) and in a plots of nine trees (99% disruption). Where peach fruit moth pheromone dispensers were deployed at a density of 1000/ha in two 2-ha areas, pheromone traps for guava moth were completely disrupted for an extended period (up to 470 days in peri-urban gardens in Mangonui and 422 days in macadamia nut orchards in Kerikeri). In contrast, traps in untreated areas over 100 m away caught 302.8 ± 128.1 moths/trap in Mangonui and 327.5 ± 78.5 moths/ trap in Kerikeri. The longer chain length in the pheromone analog has greater longevity than the natural pheromone due to its lower volatility. Chain length analogs may warrant further investigation for mating disruption in Lepidoptera, and screening using single-sensillum recording is recommended.

  7. Productivity, Disturbance and Ecosystem Size Have No Influence on Food Chain Length in Seasonally Connected Rivers

    OpenAIRE

    Warfe, Danielle M.; Jardine, Timothy D.; Pettit, Neil E.; Hamilton, Stephen K.; Pusey, Bradley J.; Bunn, Stuart E.; Davies, Peter M.; Douglas, Michael M.

    2013-01-01

    The food web is one of the oldest and most central organising concepts in ecology and for decades, food chain length has been hypothesised to be controlled by productivity, disturbance, and/or ecosystem size; each of which may be mediated by the functional trophic role of the top predator. We characterised aquatic food webs using carbon and nitrogen stable isotopes from 66 river and floodplain sites across the wet-dry tropics of northern Australia to determine the relative importance of produ...

  8. The Effect of the Chain Length on MMA Free Radicl Polymerization

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In the polymerization process of methyl methacrylate (MMA), the Arrhenius parameters (activation energy and frequency factor) of propagating reaction monotonically decrease with increasing monomer conversion. At the beginning and middle stage of the propagating reaction, the increase of radical chain length is the main reason of above mentioned change. And at the end stage, the sharp decrease of kp indicates that the activation energy is approximately incline to zero and the propagating reaction is controlled by molecular diffusion motion.

  9. Effect of side chain length on charge transport, morphology, and photovoltaic performance of conjugated polymers in bulk heterojunction solar cells

    NARCIS (Netherlands)

    Duan, C.; Willems, R.E.M.; van Franeker, J.J.; Bruijnaers, B.J.; Wienk, M.M.; Janssen, R.A.J.

    2016-01-01

    The effect of side chain length on the photovoltaic properties of conjugated polymers is systematically investigated with two sets of polymers that bear different alkyl side chain lengths based on benzodithiophene and benzo[2,1,3]thiadiazole or 5,6-difluorobenzo[2,1,3]thiadiazole. Characterization

  10. Abnormal glycogen chain length pattern, not hyperphosphorylation, is critical in Lafora disease.

    Science.gov (United States)

    Nitschke, Felix; Sullivan, Mitchell A; Wang, Peixiang; Zhao, Xiaochu; Chown, Erin E; Perri, Ami M; Israelian, Lori; Juana-López, Lucia; Bovolenta, Paola; Rodríguez de Córdoba, Santiago; Steup, Martin; Minassian, Berge A

    2017-07-01

    Lafora disease (LD) is a fatal progressive epilepsy essentially caused by loss-of-function mutations in the glycogen phosphatase laforin or the ubiquitin E3 ligase malin. Glycogen in LD is hyperphosphorylated and poorly hydrosoluble. It precipitates and accumulates into neurotoxic Lafora bodies (LBs). The leading LD hypothesis that hyperphosphorylation causes the insolubility was recently challenged by the observation that phosphatase-inactive laforin rescues the laforin-deficient LD mouse model, apparently through correction of a general autophagy impairment. We were for the first time able to quantify brain glycogen phosphate. We also measured glycogen content and chain lengths, LBs, and autophagy markers in several laforin- or malin-deficient mouse lines expressing phosphatase-inactive laforin. We find that: (i) in laforin-deficient mice, phosphatase-inactive laforin corrects glycogen chain lengths, and not hyperphosphorylation, which leads to correction of glycogen amounts and prevention of LBs; (ii) in malin-deficient mice, phosphatase-inactive laforin confers no correction; (iii) general impairment of autophagy is not necessary in LD We conclude that laforin's principle function is to control glycogen chain lengths, in a malin-dependent fashion, and that loss of this control underlies LD. © 2017 The Authors. Published under the terms of the CC BY 4.0 license.

  11. Productivity, disturbance and ecosystem size have no influence on food chain length in seasonally connected rivers.

    Science.gov (United States)

    Warfe, Danielle M; Jardine, Timothy D; Pettit, Neil E; Hamilton, Stephen K; Pusey, Bradley J; Bunn, Stuart E; Davies, Peter M; Douglas, Michael M

    2013-01-01

    The food web is one of the oldest and most central organising concepts in ecology and for decades, food chain length has been hypothesised to be controlled by productivity, disturbance, and/or ecosystem size; each of which may be mediated by the functional trophic role of the top predator. We characterised aquatic food webs using carbon and nitrogen stable isotopes from 66 river and floodplain sites across the wet-dry tropics of northern Australia to determine the relative importance of productivity (indicated by nutrient concentrations), disturbance (indicated by hydrological isolation) and ecosystem size, and how they may be affected by food web architecture. We show that variation in food chain length was unrelated to these classic environmental determinants, and unrelated to the trophic role of the top predator. This finding is a striking exception to the literature and is the first published example of food chain length being unaffected by any of these determinants. We suggest the distinctive seasonal hydrology of northern Australia allows the movement of fish predators, linking isolated food webs and potentially creating a regional food web that overrides local effects of productivity, disturbance and ecosystem size. This finding supports ecological theory suggesting that mobile consumers promote more stable food webs. It also illustrates how food webs, and energy transfer, may function in the absence of the human modifications to landscape hydrological connectivity that are ubiquitous in more populated regions.

  12. Effect of the alkyl chain length of the ionic liquid anion on polymer electrolytes properties

    International Nuclear Information System (INIS)

    Leones, Rita; Sentanin, Franciani; Nunes, Sílvia Cristina; Esperança, José M.S.S.; Gonçalves, Maria Cristina

    2015-01-01

    New polymer electrolytes (PEs) based on chitosan and three ionic liquid (IL) families ([C 2 mim][C n SO 3 ], [C 2 mim][C n SO 4 ] and [C 2 mim][diC n PO 4 ]) were synthesized by the solvent casting method. The effect of the length of the alkyl chain of the IL anion on the thermal, morphological and electrochemical properties of the PEs was studied. The solid polymer electrolytes SPE membranes were analyzed by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), polarized optical microscopy (POM), atomic force microscopy (AFM), complex impedance spectroscopy (ionic conductivity) and cyclic voltammetry (CV). The obtained results evidenced an influence of the alkyl chain length of the IL anion on the temperature of degradation, birefringence, surface roughness and ionic conductivity of the membranes. The DSC, XRD and CV results showed independency from the length of the IL-anion-alkyl chain. The PEs displayed an predominantly amorphous morphology, a minimum temperature of degradation of 135 °C, a room temperature (T = 25 °C) ionic conductivity of 7.78 × 10 −4 S cm −1 and a wide electrochemical window of ∼ 4.0 V.

  13. Productivity, disturbance and ecosystem size have no influence on food chain length in seasonally connected rivers.

    Directory of Open Access Journals (Sweden)

    Danielle M Warfe

    Full Text Available The food web is one of the oldest and most central organising concepts in ecology and for decades, food chain length has been hypothesised to be controlled by productivity, disturbance, and/or ecosystem size; each of which may be mediated by the functional trophic role of the top predator. We characterised aquatic food webs using carbon and nitrogen stable isotopes from 66 river and floodplain sites across the wet-dry tropics of northern Australia to determine the relative importance of productivity (indicated by nutrient concentrations, disturbance (indicated by hydrological isolation and ecosystem size, and how they may be affected by food web architecture. We show that variation in food chain length was unrelated to these classic environmental determinants, and unrelated to the trophic role of the top predator. This finding is a striking exception to the literature and is the first published example of food chain length being unaffected by any of these determinants. We suggest the distinctive seasonal hydrology of northern Australia allows the movement of fish predators, linking isolated food webs and potentially creating a regional food web that overrides local effects of productivity, disturbance and ecosystem size. This finding supports ecological theory suggesting that mobile consumers promote more stable food webs. It also illustrates how food webs, and energy transfer, may function in the absence of the human modifications to landscape hydrological connectivity that are ubiquitous in more populated regions.

  14. Does alkyl chain length really matter? Structure–property relationships in thermochemistry of ionic liquids

    International Nuclear Information System (INIS)

    Verevkin, Sergey P.; Zaitsau, Dzmitry H.; Emel’yanenko, Vladimir N.; Ralys, Ricardas V.; Yermalayeu, Andrei V.; Schick, Christoph

    2013-01-01

    Graphical abstract: We have shown that enthalpies of formation, enthalpies of vaporization, and lattice potential energies of alkylsubstituted imidazolium, pyridinium, and pyrrolidinium based ionic liquids with Cl and Br anions are linearly dependant on the alkyl chain length. The thermochemical properties of ILs are generally obey the group additivity rules and the values of the additivity parameters for enthalpies of formation and vaporization are very close to those for molecular compounds. - Highlights: • Alkyl substituted imidazolium, pyridinium, and pyrrolidinium based ionic liquids with anions [Cl] and [Br] were studied using DSC and ab initio methods. • The thermochemical properties of ILs generally obey the group additivity rules. • A linear dependence on the chain length of the alkyl chain of cation was found. - Abstract: DSC was used for determination of reaction enthalpies of synthesis of ionic liquids [C n mim][Cl]. A combination of DSC with quantum chemical calculations presents an indirect way to study thermodynamics of ionic liquids. The indirect procedure for vaporization enthalpy was validated with the direct experimental measurements by using thermogravimetry. First-principles calculations of the enthalpy of formation in the gaseous phase have been performed for the ionic species using the CBS-QB3 and G3 (MP2) theory. Experimental DSC data for homologous series of alkyl substituted imidazolium, pyridinium, and pyrrolidinium based ionic liquids with anions [Cl] and [Br] were collected from the literature. We have shown that enthalpies of formation, enthalpies of vaporization, and lattice potential energies are linearly dependant on the alkyl chain length. The thermochemical properties of ILs generally obey the group additivity rules and the values of the additivity parameters for enthalpies of formation and vaporization seem to be very close to those for molecular compounds

  15. Liposomes coated with hydrophobically modified hydroxyethyl cellulose: Influence of hydrophobic chain length and degree of modification.

    Science.gov (United States)

    Smistad, Gro; Nyström, Bo; Zhu, Kaizheng; Grønvold, Marthe Karoline; Røv-Johnsen, Anne; Hiorth, Marianne

    2017-08-01

    Nanoparticulate systems with an uncharged hydrophilic surface may have a great potential in mucosal drug delivery. In the present study liposomes were coated with hydrophobically modified hydroxyethyl cellulose (HM-HEC) to create a sterically stabilized liposomal system with an uncharged surface. The aim was to clarify the influence of the amount of hydrophobic modification of HEC and the length of the hydrophobic moiety, on the stability of the system and on the release properties. HM-HEC with different degrees of hydrophobic modification (1 and 2mol%) and hydrophobic groups with different chain lengths (C8, C12, C16) were included in the study, as well as fluid phase and gel phase liposomes. Both types of liposomes were successfully coated with HM-HEC containing 1mol% of hydrophobic groups, while 2mol% did not work for the intended pharmaceutical applications. The polymer coated gel phase liposomes were stable (size, zeta potential, leakage) for 24 weeks at 4°C, with no differences between the C8 and C16 HM-HEC coating. For the fluid phase liposomes a size increase was observed after 24 weeks at 4°C for all formulations; the C8 HM-HEC coated liposomes increased the most. No differences in the leakage during storage at 4°C or in the release at 35°C were observed between the fluid phase formulations. To conclude; HM-HEC with a shorter hydrophobic chain length resulted in a less stable product for the fluid phase liposomes, while no influence of the chain length was observed for the gel phase liposomes (1mol% HM). Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Comparison of CHROMagar, polymerase chain reaction-restriction fragment length polymorphism, and polymerase chain reaction-fragment size for the identification of Candida species.

    Science.gov (United States)

    Jafari, Zahra; Motamedi, Marjan; Jalalizand, Nilufar; Shokoohi, Gholam R; Charsizadeh, Arezu; Mirhendi, Hossein

    2017-09-01

    The epidemiological alteration in the distribution of Candida species, as well as the significantly increasing trend of either intrinsic or acquired resistance of some of these fungi highlights the need for a reliable method for the identification of the species. Polymerase chain reaction (PCR) is one of the methods facilitating the quick and precise identification of Candida species. The aim of this study was to compare the efficiency of CHROMagar, PCR-restriction fragment length polymorphism (PCR-RFLP), and PCR-fragment size polymorphism (PCR-FSP) assays in the identification of Candida species to determine the benefits and limitations of these methods. This study was conducted on 107 Candida strains, including 20 standard strains and 87 clinical isolates. The identification of the isolates was accomplished by using CHROMagar as a conventional method. The PCR-RFLP assay was performed on the entire internal transcribed spacer (ITS) region of ribosomal DNA (rDNA), and the consequent enzymatic digestion was compared with PCR-FSP results in which ITS1 and ITS2 regions were separately PCR amplified. In both molecular assays, yeast identification was carried out through the specific electrophoretic profiles of the PCR products. According to the results, the utilization of CHROMagar resulted in the identification of 29 (33.3%) Candida isolates, while the PCR-RFLP and PCR-FSP facilitated the identification of 83 (95.4%) and 80 (91.9%) clinical isolates, respectively. The obtained concordances between CHROMagar and PCR-RFLP, between CHROMagar and PCR-FSP, as well as between PCR-RFLP and PCR-FSP were 0.23, 0.20, and 0.77, respectively. The recognition of the benefits and limitations of PCR methods allows for the selection of the most efficient technique for a fast and correct differentiation. The PCR-RFLP and PCR-FSP assays had satisfactory concordance. The PCR-FSP provides a rapid, technically simple, and cost-effective method for the identification of Candida species

  17. Diversion of phagosome trafficking by pathogenic Rhodococcus equi depends on mycolic acid chain length.

    Science.gov (United States)

    Sydor, Tobias; von Bargen, Kristine; Hsu, Fong-Fu; Huth, Gitta; Holst, Otto; Wohlmann, Jens; Becken, Ulrike; Dykstra, Tobias; Söhl, Kristina; Lindner, Buko; Prescott, John F; Schaible, Ulrich E; Utermöhlen, Olaf; Haas, Albert

    2013-03-01

    Rhodococcus equi is a close relative of Mycobacterium spp. and a facultative intracellular pathogen which arrests phagosome maturation in macrophages before the late endocytic stage. We have screened a transposon mutant library of R. equi for mutants with decreased capability to prevent phagolysosome formation. This screen yielded a mutant in the gene for β-ketoacyl-(acyl carrier protein)-synthase A (KasA), a key enzyme of the long-chain mycolic acid synthesizing FAS-II system. The longest kasA mutant mycolic acid chains were 10 carbon units shorter than those of wild-type bacteria. Coating of non-pathogenic E. coli with purified wild-type trehalose dimycolate reduced phagolysosome formation substantially which was not the case with shorter kasA mutant-derived trehalose dimycolate. The mutant was moderately attenuated in macrophages and in a mouse infection model, but was fully cytotoxic.Whereas loss of KasA is lethal in mycobacteria, R. equi kasA mutant multiplication in broth was normal proving that long-chain mycolic acid compounds are not necessarily required for cellular integrity and viability of the bacteria that typically produce them. This study demonstrates a central role of mycolic acid chain length in diversion of trafficking by R. equi. © 2012 Blackwell Publishing Ltd.

  18. The role of discharge variation in scaling of drainage area and food chain length in rivers

    Science.gov (United States)

    Sabo, John L.; Finlay, Jacques C.; Kennedy, Theodore A.; Post, David M.

    2010-01-01

    Food chain length (FCL) is a fundamental component of food web structure. Studies in a variety of ecosystems suggest that FCL is determined by energy supply, environmental stability, and/or ecosystem size, but the nature of the relationship between environmental stability and FCL, and the mechanism linking ecosystem size to FCL, remain unclear. Here we show that FCL increases with drainage area and decreases with hydrologic variability and intermittency across 36 North American rivers. Our analysis further suggests that hydrologic variability is the mechanism underlying the correlation between ecosystem size and FCL in rivers. Ecosystem size lengthens river food chains by integrating and attenuating discharge variation through stream networks, thereby enhancing environmental stability in larger river systems.

  19. Micellar dipolar rearrangement is sensitive to hydrophobic chain length: Implication for structural switchover of piroxicam.

    Science.gov (United States)

    Sethy, Dasaratha; Chakraborty, Hirak

    2016-10-01

    The interfacial properties of the membrane are exceptionally vital in drug-membrane interaction. They not only select out a particular prototropic form of the drug molecule for incorporation, but are also potent enough to induce structural switchover of these drugs in several cases. In this work, we quantitatively monitored the change in dipolar rearrangement of the micellar interface (as a simplified membrane mimic) by measuring the dielectric constant and dipole potential with the micellization of SDS at pH 3.6. The dielectric constant and dipole potential were measured utilizing the fluorescence of polarity sensitive probe, pyrene and potential-sensitive probe, di-8-ANEPPS, respectively. Our study demonstrates that the change in dipolar rearrangement directly influences the switchover equilibrium between the anionic and neutral from of piroxicam. We have further extended our work to evaluate the effect of hydrophobic chain length of the surfactants on the dipolar rearrangement and its effect on the structural switchover of piroxicam. It is interesting that the extent of switchover of piroxicam is directly correlated with the dipolar rearrangement induced bythe varying hydrophobic chain length of the surfactants. To the best of our knowledge, our results constitute the first report to show the dependence of dipole potential on the hydrophobic chain length of the surfactant and demonstrate that the dipolar rearrangement directly tunes the extent of structural switchover of piroxicam, which was so far only intuitive. We consider that this new finding would have promising implication in drug distribution and drug efficacy. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  20. Dependence of micelle size and shape on detergent alkyl chain length and head group.

    Directory of Open Access Journals (Sweden)

    Ryan C Oliver

    Full Text Available Micelle-forming detergents provide an amphipathic environment that can mimic lipid bilayers and are important tools for solubilizing membrane proteins for functional and structural investigations in vitro. However, the formation of a soluble protein-detergent complex (PDC currently relies on empirical screening of detergents, and a stable and functional PDC is often not obtained. To provide a foundation for systematic comparisons between the properties of the detergent micelle and the resulting PDC, a comprehensive set of detergents commonly used for membrane protein studies are systematically investigated. Using small-angle X-ray scattering (SAXS, micelle shapes and sizes are determined for phosphocholines with 10, 12, and 14 alkyl carbons, glucosides with 8, 9, and 10 alkyl carbons, maltosides with 8, 10, and 12 alkyl carbons, and lysophosphatidyl glycerols with 14 and 16 alkyl carbons. The SAXS profiles are well described by two-component ellipsoid models, with an electron rich outer shell corresponding to the detergent head groups and a less electron dense hydrophobic core composed of the alkyl chains. The minor axis of the elliptical micelle core from these models is constrained by the length of the alkyl chain, and increases by 1.2-1.5 Å per carbon addition to the alkyl chain. The major elliptical axis also increases with chain length; however, the ellipticity remains approximately constant for each detergent series. In addition, the aggregation number of these detergents increases by ∼16 monomers per micelle for each alkyl carbon added. The data provide a comprehensive view of the determinants of micelle shape and size and provide a baseline for correlating micelle properties with protein-detergent interactions.

  1. Lipid polymorphism of mixtures of dioleoylphosphatidylethanolamine and saturated and monounsaturated phosphatidylcholines of various chain lengths

    International Nuclear Information System (INIS)

    Tate, M.W.; Gruner, S.M.

    1987-01-01

    The L/sub α/-H/sub II/ phase transition behavior of many lipid-water liquid crystals is dominated by the competition between the tendency to curl the lipid layers to an intrinsic radius of curvature and opposing hydrocarbon packing constraints. In particular, packing constraints can increase the free energy of the inverted hexagonal (H/sub II/) phase as compared to that of the lamellar (L/sub α/) phase. This is especially true where the lipid molecule is not long enough to reach into the corners of the lattice in large hexagonal structures necessitated by a large radius of curvature.In this paper it is shown that the addition of a minor fraction long-chain lipid to a system of otherwise uniform chain composition can also relax packing constraints, thereby lowering the lamellar to hexagonal transition temperature. For the specific systems used, dioleoylphosphatidylethanolamine (di-18:1/sub c/-PE) with minor fractions of 1,2-diacyl-sn-glycero-3-phosphocholines [di-n:1/sub c/-PC (n = 14, 18, 22, and 24)], the observed H/sub II/lattices systematically increased in size with increasing chain length suggesting that the chain length also may affect the intrinsic curvature of the mixture. These experiments demonstrate that the lipid shape concept, which is a qualitative expression of the concept quantitatively described by the intrinsic radius of curvature, is insufficient to understand the L/sub α/-H/sub II/ transition. It is necessary to, at least, consider the competition between curvature and packing

  2. Alkyl chain length impacts the antioxidative effect of lipophilized ferulic acid in fish oil enriched milk

    DEFF Research Database (Denmark)

    Sørensen, Ann-Dorit Moltke; Lyneborg, Karina Sieron; Villeneuve, Pierre

    2015-01-01

    Lipophilization of phenolics by esterification with fatty alcohols may alter their localization in an emulsion and thereby their antioxidant efficacy. In this study, synthesized unbranched alkyl ferulates were evaluated as antioxidants in fish oil enriched milk. Lipid oxidation was determined...... by peroxide values and concentration of volatile oxidation products. A cut-off effect in the antioxidant efficacy in relation to the alkyl chain length was observed. The most efficient alkyl ferulate was methyl ferulate followed by ferulic acid and butyl ferulate, whereas octyl ferulate was prooxidative...

  3. Perspectives of medium chain length poly(hydroxyalkanoates), a versatile set of bacterial bioplastics

    Science.gov (United States)

    Witholt; Kessler

    1999-06-01

    Medium chain length (mcl) poly(hydroxyalkanoic acids) (PHAs) are polyesters accumulated by fluorescent Pseudomonads and other bacteria. Work on the genetics of mcl-PHA formation has led to polymer synthesis in recombinant bacteria and plants. Several high and medium cost applications are now emerging. With optimized bacterial mcl-PHA synthesis on inexpensive agro-substrates and the development of plant-based mcl-PHAs in the next decade, the production economics of these bioplastics will ultimately permit their sustainable production for bulk applications.

  4. Shape control of the magnetic iron oxide nanoparticles under different chain length of reducing agents

    International Nuclear Information System (INIS)

    Ngoi, Kuan Hoon; Chia, Chin-Hua; Zakaria, Sarani; Chiu, Wee Siong

    2015-01-01

    We report on the effect of using reducing agents with different chain-length on the synthesis of iron oxide nanoparticles by thermal decomposition of iron (III) acetylacetonate in 1-octadecene. This modification allows us to control the shape of nanoparticles into spherical and cubic iron oxide nanoparticles. The highly monodisperse 14 nm spherical nanoparticles are obtained under 1,2-dodecanediol and average 14 nm edge-length cubic iron oxide nanoparticles are obtained under 1,2-tetradecanediol. The structural characterization such as transmission electron microscope (TEM) and X-ray diffraction (XRD) shows similar properties between two particles with different shapes. The vibrating sample magnetometer (VSM) shows no significant difference between spherical and cubic nanoparticles, which are 36 emu/g and 37 emu/g respectively and superparamagnetic in nature

  5. Shape control of the magnetic iron oxide nanoparticles under different chain length of reducing agents

    Energy Technology Data Exchange (ETDEWEB)

    Ngoi, Kuan Hoon; Chia, Chin-Hua, E-mail: chia@ukm.edu.my; Zakaria, Sarani [School of Applied Physics, Faculty Science and Technology, University Kebangsaan Malaysia 43600 UKM Bangi, Selangor (Malaysia); Chiu, Wee Siong [Low Dimensional Materials Research Centre, Department of Physics, Faculty of Science, University of Malaya, 50603 Lembah Pantai, Kuala Lumpur (Malaysia)

    2015-09-25

    We report on the effect of using reducing agents with different chain-length on the synthesis of iron oxide nanoparticles by thermal decomposition of iron (III) acetylacetonate in 1-octadecene. This modification allows us to control the shape of nanoparticles into spherical and cubic iron oxide nanoparticles. The highly monodisperse 14 nm spherical nanoparticles are obtained under 1,2-dodecanediol and average 14 nm edge-length cubic iron oxide nanoparticles are obtained under 1,2-tetradecanediol. The structural characterization such as transmission electron microscope (TEM) and X-ray diffraction (XRD) shows similar properties between two particles with different shapes. The vibrating sample magnetometer (VSM) shows no significant difference between spherical and cubic nanoparticles, which are 36 emu/g and 37 emu/g respectively and superparamagnetic in nature.

  6. Hydraulic Design Criteria for Spacer Grids of Nuclear Fuel Element

    International Nuclear Information System (INIS)

    Juanico, Luis; Brasnarof, Daniel

    2000-01-01

    In this paper a hydraulic model for calculating the pressure drop on the CARA spacer grids is extended.This model is validated and feedback from experimental hydraulic test performed in a low pressure loop.The importance of the spacer grid geometric parameter (that is, its thickness and length, the number and kind of their fix spacer), developing hydraulic design criteria for spacer grid on fuel element

  7. Effect of Chain Length Compatibility of Alcohols on Muscovite Flotation by Dodecyl Amine

    Directory of Open Access Journals (Sweden)

    Li Wang

    2018-04-01

    Full Text Available A portion of dodecyl amine (DDA in a muscovite flotation system was replaced with alcohols with different carbon-chain lengths. These alcohols included octanol (OCT; decanol (DEC; dodecanol (DOD; and tetradecanol (TER. The muscovite adsorption behavior of the mixed DDA and alcohol systems were investigated through zeta potential; contact angle; and adsorption quantity tests. Single-mineral flotation tests showed that the muscovite-collecting power of the mixed DDA/alcohol (OCT, DEC, or DOD system was stronger than that of the pure DDA system. The muscovite-collecting power of the collector systems decreased in the following order: DDA/DEC > DDA/OCT > DDA/DEC > DDA > DDA/TER. Zeta potential and contact angle analysis indicated that when combined with DDA; alcohols physically adsorbed on the surfaces of muscovite. This behavior improved the hydrophobicity of muscovite. Furthermore, adsorption analysis revealed that synergy between DDA and alcohol enhanced the adsorption of alcohol on muscovite. DDA has a dominant role in synergistic adsorption; whereas alcohol has a supporting role. Among all tested alcohols; DDA and DOD exhibit the highest synergetic adsorption effect because of their similar carbon-chain lengths. This similarity promotes the formation of a compact adsorption layer on the muscovite surface.

  8. Effect of the Alkyl Chain Length on the Adsorption Properties of Malonamide Chelating Resins

    International Nuclear Information System (INIS)

    Ismail, I.M.; Nogami, M.; Suzuki, K.

    2004-01-01

    In order to investigate the effect of the alkyl chain length of malonamide chelating resins on the rate of uptake of U(VI) ions and Ce(III) Ions, lV,N,N',N'-tetraethyl malonamide (TEMA), N,N,N',N'-tetra-n-propyl malonamide (TPrMA), lV,lV,N',N'-tetra-n-butyl malonamide (TBMA) and N,l V,N',N'-tetra-n-pentyl malonamide (Tamp) chelating resins were synthesized by chemically bonding these function groups to CMS-DVB co-polymer beads. N,lV,N',N'-tetraphenyl malonamide (TPhMA) chelating resin was also investigated and the results of these resins were compared with those of N,lY,N',N-tetra methylmalonamide (TMMA) previously reported. The batch technique was used to study the thermodynamic equilibrium, in terms of distribution coefficient, and the kinetics of the adsorption U(VI) and Ce(III) ions from 3 M HNO 3 , Acid, and 3 M NaNO 3 + 0.05 M HNO 3 , Salt, media. The introduction ratio of the function group into the polymer base and the uptake of U(VI) ions and C(III) ions were found to decrease with the increase in the alkyl chain length. The uptake was found to diminish in case of TPhMA resin due to the decrease of the function group ratio and the steric-hinder effect

  9. Pruned-enriched Rosenbluth method: Simulations of θ polymers of chain length up to 1000000

    International Nuclear Information System (INIS)

    Grassberger, P.

    1997-01-01

    We present an algorithm for simulating flexible chain polymers. It combines the Rosenbluth-Rosenbluth method with recursive enrichment. Although it can be applied also in more general situations, it is most efficient for three-dimensional θ polymers on the simple-cubic lattice. There it allows high statistics simulations of chains of length up to N=10 6 . For storage reasons, this is feasable only for polymers in a finite volume. For free θ polymers in infinite volume, we present very high statistics runs with N=10000. These simulations fully agree with previous simulations made by Hegger and Grassberger [J. Chem. Phys. 102, 6681 (1995)] with a similar but less efficient algorithm, showing that logarithmic corrections to mean field behavior are much stronger than predicted by field theory. But the finite volume simulations show that the density inside a collapsed globule scales with the distance from the θ point as predicted by mean field theory, in contrast to claims in the work mentioned above. In addition to the simple-cubic lattice, we also studied two versions of the bond fluctuation model, but with much shorter chains. Finally, we show that our method can be applied also to off-lattice models, and illustrate this with simulations of a model studied in detail by Freire et al. [Macromolecules 19, 452 (1986) and later work]. copyright 1997 The American Physical Society

  10. Alignment-free Transcriptomic and Metatranscriptomic Comparison Using Sequencing Signatures with Variable Length Markov Chains.

    Science.gov (United States)

    Liao, Weinan; Ren, Jie; Wang, Kun; Wang, Shun; Zeng, Feng; Wang, Ying; Sun, Fengzhu

    2016-11-23

    The comparison between microbial sequencing data is critical to understand the dynamics of microbial communities. The alignment-based tools analyzing metagenomic datasets require reference sequences and read alignments. The available alignment-free dissimilarity approaches model the background sequences with Fixed Order Markov Chain (FOMC) yielding promising results for the comparison of microbial communities. However, in FOMC, the number of parameters grows exponentially with the increase of the order of Markov Chain (MC). Under a fixed high order of MC, the parameters might not be accurately estimated owing to the limitation of sequencing depth. In our study, we investigate an alternative to FOMC to model background sequences with the data-driven Variable Length Markov Chain (VLMC) in metatranscriptomic data. The VLMC originally designed for long sequences was extended to apply to high-throughput sequencing reads and the strategies to estimate the corresponding parameters were developed. The flexible number of parameters in VLMC avoids estimating the vast number of parameters of high-order MC under limited sequencing depth. Different from the manual selection in FOMC, VLMC determines the MC order adaptively. Several beta diversity measures based on VLMC were applied to compare the bacterial RNA-Seq and metatranscriptomic datasets. Experiments show that VLMC outperforms FOMC to model the background sequences in transcriptomic and metatranscriptomic samples. A software pipeline is available at https://d2vlmc.codeplex.com.

  11. Characterization of a Novel Subgroup of Extracellular Medium-Chain-Length Polyhydroxyalkanoate Depolymerases from Actinobacteria

    Science.gov (United States)

    Gangoiti, Joana; Santos, Marta; Prieto, María Auxiliadora; de la Mata, Isabel; Llama, María J.

    2012-01-01

    Nineteen medium-chain-length (mcl) poly(3-hydroxyalkanoate) (PHA)-degrading microorganisms were isolated from natural sources. From them, seven Gram-positive and three Gram-negative bacteria were identified. The ability of these microorganisms to hydrolyze other biodegradable plastics, such as short-chain-length (scl) PHA, poly(ε-caprolactone) (PCL), poly(ethylene succinate) (PES), and poly(l-lactide) (PLA), has been studied. On the basis of the great ability to degrade different polyesters, Streptomyces roseolus SL3 was selected, and its extracellular depolymerase was biochemically characterized. The enzyme consisted of one polypeptide chain of 28 kDa with a pI value of 5.2. Its maximum activity was observed at pH 9.5 with chromogenic substrates. The purified enzyme hydrolyzed mcl PHA and PCL but not scl PHA, PES, and PLA. Moreover, the mcl PHA depolymerase can hydrolyze various substrates for esterases, such as tributyrin and p-nitrophenyl (pNP)-alkanoates, with its maximum activity being measured with pNP-octanoate. Interestingly, when poly(3-hydroxyoctanoate-co-3-hydroxyhexanoate [11%]) was used as the substrate, the main hydrolysis product was the monomer (R)-3-hydroxyoctanoate. In addition, the genes of several Actinobacteria strains, including S. roseolus SL3, were identified on the basis of the peptide de novo sequencing of the Streptomyces venezuelae SO1 mcl PHA depolymerase by tandem mass spectrometry. These enzymes did not show significant similarity to mcl PHA depolymerases characterized previously. Our results suggest that these distinct enzymes might represent a new subgroup of mcl PHA depolymerases. PMID:22865072

  12. The effect of carbon chain length of starting materials on the formation of carbon dots and their optical properties

    Science.gov (United States)

    Pan, Xiaohua; Zhang, Yan; Sun, Xiaobo; Pan, Wei; Yu, Guifeng; Si, Shuxin; Wang, Jinping

    2018-04-01

    Carbon dots (CDs) have attracted increasing attention due to their high performances and potential applications in wide range of areas. However, their emission mechanism is not clear so far. In order to reveal more factors contributing to the emission of CDs, the effect of carbon chain length of starting materials on the formation of CDs and their optical properties was experimentally investigated in this work. In order to focus on the effect of carbon chain length, the starting materials with C, O, N in fully identical forms and only carbon chain lengths being different were selected for synthesizing CDs, including citric acid (CA) and adipic acid (AA) as carbon sources, and diamines with different carbon chain lengths (H2N(CH2)nNH2, n = 2, 4, 6) as nitrogen sources, as well as ethylenediamine (EDA) as nitrogen source and diacids with different carbon chain lengths (HOOC(CH2)nCOOH, n = 0, 2, 4, 6) as carbon sources. Therefore, the effect of carbon chain length of starting materials on the formation and optical properties of CDs can be systematically investigated by characterizing and comparing the structures and optical properties of as-prepared nine types of CDs. Moreover, the density of –NH2 on the surface of the CDs was quantitatively detected by a spectrophotometry so as to elucidate the relationship between the –NH2 related surface state and the optical properties.

  13. Soliton scatterings by impurities in a short-length sine-Gordon chain

    International Nuclear Information System (INIS)

    Dikande, A.M.; Kofane, T.C.

    1995-07-01

    The scattering of soliton by impurities at the frontiers of a finite-length region of an infinite sine-Gordon chain is analyzed. The impurities consist of two isotopic inhomogeneities installed at the boundaries of the finite-length region. The soliton solution in the region is found in term of snoidal sine-Gordon soliton which properly takes into account the effects of the boundaries. By contrast, the soliton solutions in the neighboring sides of the region are obtained in terms of the so-called large-amplitude, localized kinks with limiting spatial extensions at x → ± ∞, which is equal ±π. Using the continuity of these soliton solutions at the frontiers as well as appropriate boundary conditions, it is shown that the soliton may be either i) reflected by the incident impurity; ii) trapped (with oscillating motions) between the two impurities (i.e. inside the infinite region); or iii) transmitted by the second impurity into the third, infinitely extended region. The threshold velocities for the reflection and transmission into different regions are found and shown to vary exponentially as a function of the length of the bounded region. The frequency of soliton oscillations between the impurities has also been calculated in some acceptable limit. (author). 28 refs, 1 fig

  14. Spacer for supporting fuel element boxes

    International Nuclear Information System (INIS)

    Wild, E.

    1979-01-01

    A spacer plate unit arranged externally on each side and at a predetermined level of a polygonal fuel element box for mutually supporting, with respect to one another, a plurality of the fuel element boxes forming a fuel element bundle, is formed of a first and a second spacer plate part each having the same length and the same width and being constituted of unlike first and second materials, respectively. The first and second spacer plate parts of the several spacer plate units situated at the predetermined level are arranged in an alternating continuous series when viewed in the peripheral direction of the fuel element box, so that any two spacer plate units belonging to face-to-face oriented sides of two adjoining fuel element boxes in the fuel element bundle define interfaces of unlike materials

  15. Bat white-nose syndrome: A real-time TaqMan polymerase chain reaction test targeting the intergenic spacer region of Geomyces destructans

    Science.gov (United States)

    Laura K Muller; Jeffrey M. Lorch; Daniel L. Lindner; Michael O' Connor; Andrea Gargas; David S. Blehert

    2013-01-01

    The fungus Geomyces destructans is the causative agent of white-nose syndrome (WNS), a disease that has killed millions of North American hibernating bats. We describe a real-time TaqMan PCR test that detects DNA from G. destructans by targeting a portion of the multicopy intergenic spacer region of the rRNA gene complex. The...

  16. Pressure Drop Test of Hybrid Mixing Vane Spacer Grid

    Energy Technology Data Exchange (ETDEWEB)

    Oh, D. S.; Chang, S. K.; Kim, B. D.; Chun, S. Y.; Chun, T. H

    2007-08-15

    The pressure loss test has been accomplished in the test section containing 5x5 rod bundle with a length of 2 m including 3 spacer grids. The test has been performed for the 5 kinds of spacer grids to compare the pressure loss characteristics: 1. Plain spacer grid which has the same body of the Hybrid but without vane (Plain), 2. Hybrid Vane spacer grid (Hybrid), 3. Hybrid-SC spacer grid which is constructed with coined, chamfered strip and is fabricated by spot welding, 4. Hybrid-LC spacer grid which is constructed with coined, chamfered strip and is fabricated by line welding along intersection line, 5. Westinghouse spacer grid with split vane (Plus-7). The pressure loss coefficient of the Plain, Hybrid, Hybrid-SC, Hybrid-LC, and Plus-7 spacer grid is 0.93, 1.15, 1.02, 1.04, and 1.08, respectively.

  17. Chain length effects on the vibrational structure and molecular interactions in the liquid normal alkyl alcohols

    Science.gov (United States)

    Kiefer, Johannes; Wagenfeld, Sabine; Kerlé, Daniela

    2018-01-01

    Alkyl alcohols are widely used in academia, industry, and our everyday lives, e.g. as cleaning agents and solvents. Vibrational spectroscopy is commonly used to identify and quantify these compounds, but also to study their structure and behavior. However, a comprehensive investigation and comparison of all normal alkanols that are liquid at room temperature has not been performed, surprisingly. This study aims at bridging this gap with a combined experimental and computational effort. For this purpose, the alkyl alcohols from methanol to undecan-1-ol have been analyzed using infrared and Raman spectroscopy. A detailed assignment of the individual peaks is presented and the influence of the alkyl chain length on the hydrogen bonding network is discussed. A 2D vibrational mapping allows a straightforward visualization of the effects. The conclusions drawn from the experimental data are backed up with results from Monte Carlo simulations using the simulation package Cassandra.

  18. Synthesis of medium-chain length capsinoids from coconut oil catalyzed by Candida rugosa lipases.

    Science.gov (United States)

    Trbojević Ivić, Jovana; Milosavić, Nenad; Dimitrijević, Aleksandra; Gavrović Jankulović, Marija; Bezbradica, Dejan; Kolarski, Dušan; Veličković, Dušan

    2017-03-01

    A commercial preparation of Candida rugosa lipases (CRL) was tested for the production of capsinoids by esterification of vanillyl alcohol (VA) with free fatty acids (FA) and coconut oil (CO) as acyl donors. Screening of FA chain length indicated that C8-C12 FA (the most common FA found in CO triglycerides) are the best acyl-donors, yielding 80-85% of their specific capsinoids. Hence, when CO, which is rich in these FA, was used as the substrate, a mixture of capsinoids (vanillyl caprylate, vanillyl decanoate and vanillyl laurate) was obtained. The findings presented here suggest that our experimental method can be applied for the enrichment of CO with capsinoids, thus giving it additional health promoting properties. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. The Role of Chain Length in Nonergodicity Factor and Fragility of Polymers

    DEFF Research Database (Denmark)

    Dalle-Ferrie, Cecile; Niss, Kristine; Sokolov, Alexei

    2010-01-01

    The mechanism that leads to different fragility values upon approaching the glass transition remains a topic of active discussion. Many researchers are trying to find an answer in the properties of the frozen glassy state. Following this approach, we focus here on a previously proposed relationship...... between the fragility of glass-formers and their nonergodicity factor, determined by inelastic X-ray scattering (IXS) in the glass. We extend this molecular liquid study to two model polymers— polystyrene (PS) and polyisobutylene (PIB)—for which we change the molecular weight. Polymers offer...... the opportunity to change the fragility without altering the chemical structure, just by changing the chain length. Thus, we specifically chose PS and PIB because they exhibit opposite dependences of fragility with molecular weight. Our analysis for these two polymers reveals no unique correlation between...

  20. Effect of surfactant chain length on drug release kinetics from microemulsion-laden contact lenses.

    Science.gov (United States)

    Maulvi, Furqan A; Desai, Ankita R; Choksi, Harsh H; Patil, Rahul J; Ranch, Ketan M; Vyas, Bhavin A; Shah, Dinesh O

    2017-05-30

    The effect of surfactant chain lengths [sodium caprylate (C 8 ), Tween 20 (C 12 ), Tween 80 (C 18 )] and the molecular weight of block copolymers [Pluronic F68 and Pluronic F 127] were studied to determine the stability of the microemulsion and its effect on release kinetics from cyclosporine-loaded microemulsion-laden hydrogel contact lenses in this work. Globule size and dilution tests (transmittance) suggested that the stability of the microemulsion increases with increase in the carbon chain lengths of surfactants and the molecular weight of pluronics. The optical transmittance of direct drug-laden contact lenses [DL-100] was low due to the precipitation of hydrophobic drugs in the lenses, while in microemulsion-laden lenses, the transmittance was improved when stability of the microemulsion was achieved. The results of in vitro release kinetics revealed that drug release was sustained to a greater extent as the stability of microemulsion was improved as well. This was evident in batch PF127-T80, which showed sustained release for 15days in comparison to batch DL-100, which showed release up to 7days. An in vivo drug release study in rabbit tear fluid showed significant increase in mean residence time (MRT) and area under curve (AUC) with PF-127-T80 lenses (stable microemulsion) in comparison to PF-68-SC lenses (unstable microemulsion) and DL-100 lenses. This study revealed the correlation between the stability of microemulsion and the release kinetics of drugs from contact lenses. Thus, it was inferred that the stable microemulsion batches sustained the release of hydrophobic drugs, such as cyclosporine from contact lenses for an extended period of time without altering critical lens properties. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Tuning the Mechanical Properties of Polymer Nanocomposites Filled with Grafted Nanoparticles by Varying the Grafted Chain Length and Flexibility

    Directory of Open Access Journals (Sweden)

    Zixuan Wang

    2016-08-01

    Full Text Available By employing coarse-grained molecular dynamics simulation, we simulate the spatial organization of the polymer-grafted nanoparticles (NPs in homopolymer matrix and the resulting mechanical performance, by particularly regulating the grafted chain length and flexibility. The morphologies ranging from the agglomerate, cylinder, sheet, and string to full dispersion are observed, by gradually increasing the grafted chain length. The radial distribution function and the total interaction energy between NPs are calculated. Meanwhile, the stress–strain behavior of each morphology and the morphological evolution during the uniaxial tension are simulated. In particular, the sheet structure exhibits the best mechanical reinforcement compared to other morphologies. In addition, the change of the grafted chain flexibility to semi-flexibility leads to the variation of the morphology. We also find that at long grafted chain length, the stress–strain behavior of the system with the semi-flexible grafted chain begins to exceed that of the system with the flexible grafted chain, attributed to the physical inter-locking interaction between the matrix and grafted polymer chains. A similar transition trend is as well found in the presence of the interfacial chemical couplings between grafted and matrix polymer chains. In general, this work is expected to help to design and fabricate high performance polymer nanocomposites filled with grafted NPs with excellent and controllable mechanical properties.

  2. Use of length heterogeneity polymerase chain reaction (LH-PCR as non-invasive approach for dietary analysis of Svalbard reindeer, Rangifer tarandus platyrhynchus.

    Directory of Open Access Journals (Sweden)

    Sungbae Joo

    Full Text Available To efficiently investigate the forage preference of Svalbard reindeer (Rangifer tarandus platyrhynchus, we applied length-heterogeneity polymerase chain reaction (LH-PCR based on length differences of internal transcribed spacer (ITS regions of ribosomal RNA (rRNA to fecal samples from R. tarandus platyrhynchus. A length-heterogeneity (LH database was constructed using both collected potential food sources of Svalbard reindeer and fecal samples, followed by PCR, cloning and sequencing. In total, eighteen fecal samples were collected between 2011 and 2012 from 2 geographic regions and 15 samples were successfully amplified by PCR. The LH-PCR analysis detected abundant peaks, 18.6 peaks on an average per sample, ranging from 100 to 500 bp in size and showing distinct patterns associated with both regions and years of sample collection. Principal component analysis (PCA resulted in clustering of 15 fecal samples into 3 groups by the year of collection and region with a statistically significant difference at 99.9% level. The first 2 principal components (PCs explained 71.1% of the total variation among the samples. Through comparison with LH database and identification by cloning and sequencing, lichens (Stereocaulon sp. and Ochrolechia sp. and plant species (Salix polaris and Saxifraga oppositifolia were detected as the food sources that contributed most to the Svalbard reindeer diet. Our results suggest that the use of LH-PCR analysis would be a non-invasive and efficient monitoring tool for characterizing the foraging strategy of Svalbard reindeer. Additionally, combining sequence information would increase its resolving power in identification of foraged diet components.

  3. Supplemental Dietary Inulin of Variable Chain Lengths Alters Intestinal Bacterial Populations in Young Pigs123

    Science.gov (United States)

    Patterson, Jannine K.; Yasuda, Koji; Welch, Ross M.; Miller, Dennis D.; Lei, Xin Gen

    2010-01-01

    Previously, we showed that supplementation of diets with short-chain inulin (P95), long-chain inulin (HP), and a 50:50 mixture of both (Synergy 1) improved body iron status and altered expression of the genes involved in iron homeostasis and inflammation in young pigs. However, the effects of these 3 types of inulin on intestinal bacteria remain unknown. Applying terminal restriction fragment length polymorphism analysis, we determined the abundances of luminal and adherent bacterial populations from 6 segments of the small and large intestines of pigs (n = 4 for each group) fed an iron-deficient basal diet (BD) or the BD supplemented with 4% of P95, Synergy 1, or HP for 5 wk. Compared with BD, all 3 types of inulin enhanced (P inulin on bacterial populations in the lumen contents were found. Meanwhile, all 3 types of inulin suppressed the less desirable bacteria Clostridium spp. and members of the Enterobacteriaceae in the lumen and mucosa of various gut segments. Our findings suggest that the ability of dietary inulin to alter intestinal bacterial populations may partially account for its iron bioavailability-promoting effect and possibly other health benefits. PMID:20980641

  4. Determination of locust bean gum and guar gum by polymerase chain reaction and restriction fragment length polymorphism analysis.

    Science.gov (United States)

    Meyer, K; Rosa, C; Hischenhuber, C; Meyer, R

    2001-01-01

    A polymerase chain reaction (PCR) was developed to differentiate the thickening agents locust bean gum (LBG) and the cheaper guar gum in finished food products. Universal primers for amplification of the intergenic spacer region between trnL 3' (UAA) exon and trnF (GAA) gene in the chloroplast (cp) genome and subsequent restriction analysis were applied to differentiate guar gum and LBG. The presence of guar gum powder added to LBG powder was detectable. Based on data obtained from sequencing this intergenic spacer region, a second PCR method for the specific detection of guar gum DNA was also developed. This assay detected guar gum powder in LBG in amounts as low as 1% (w/w). Both methods successfully detected guar gum and/or LBG in ice cream stabilizers and in foodstuffs, such as dairy products, ice cream, dry seasoning mixes, a finished roasting sauce, and a fruit jelly product, but not in products with highly degraded DNA, such as tomato ketchup and sterilized chocolate cream. Both methods detected guar gum and LBG in ice cream and fresh cheese at levels <0.1%.

  5. Molecular identification of Candida species isolated from cases of neonatal candidemia using polymerase chain reaction-restriction fragment length polymorphism in a tertiary care hospital

    Directory of Open Access Journals (Sweden)

    Akeela Fatima

    2017-01-01

    Full Text Available Context: Candida spp. is an emerging cause of bloodstream infections worldwide. Delay in speciation of Candida isolates by conventional methods and resistance to antifungal drugs in various Candida species are responsible for the increase in morbidity and mortality due to candidemia. Hence, the rapid identification of Candida isolates is very important for the proper management of patients with candidemia. Aims: The aim was to re-evaluate the identification of various Candida spp. by polymerase chain reaction (PCR-restriction fragment length polymorphism (RFLP and to evaluate the accuracy, speed, and cost of phenotypic methodology versus PCR-RFLP. Settings and Design: Hospital-based cross-sectional study. Materials and Methods: Ninety consecutive clinical isolates of seven Candida species, isolated from blood of neonates and identified by routine phenotypic methods, were re-evaluated using universal primers internal transcribed spacer 1 (ITS1 and ITS4 for PCR amplification and Msp I restriction enzyme for RFLP. Statistical Analysis Used: Kappa test for agreement. Results: The results of PCR-RFLP were 100% in agreement with those obtained using conventional phenotypic methods. Identification could be achieved within 3 work days by both the methods. Our routine methods proved to be cost effective than PCR-RFLP. Conclusions: We can continue with our routine phenotypic methods and PCR-RFLP can be used for periodic quality control or when conventional methods fail to identify a species.

  6. Molecular identification of similar species of the genus Biomphalaria (Mollusca: Planorbidae determined by a polymerase chain reaction-restriction fragment length polymorphism

    Directory of Open Access Journals (Sweden)

    Caldeira Roberta Lima

    1998-01-01

    Full Text Available The freshwater snails Biomphalaria straminea, B. intermedia, B. kuhniana and B. peregrina, are morphologically similar; based on this similarity the first three species were therefore grouped in the complex B. straminea. The morphological identification of these species is based on characters such as vaginal wrinkling, relation between prepuce: penial sheath:deferens vas and number of muscle layers in the penis wall. In this study the polymerase chain reaction restriction fragment length polymorphism technique was used for molecular identification of these molluscs. This technique is based on the amplification of the internal transcribed spacer regions ITS1 e ITS2 of the ribosomal RNA gene and subsequent digestion of these fragments by restriction enzymes. Six enzymes were tested: Dde I, Mnl I, Hae III, Rsa I, Hpa II e Alu I. The restriction patterns obtained with DdeI presented the best profile for separation of the four species of Biomphalaria. The profiles obtained with all the enzymes were used to estimate the genetic distances among the species through analysis of common banding patterns.

  7. Critical temperatures and a critical chain length in saturated diacylphosphatidylcholines: calorimetric, ultrasonic and Monte Carlo simulation study of chain-melting/ordering in aqueous lipid dispersions.

    Science.gov (United States)

    Kharakoz, Dmitry P; Panchelyuga, Maria S; Tiktopulo, Elizaveta I; Shlyapnikova, Elena A

    2007-12-01

    Chain-ordering/melting transition in a series of saturated diacylphosphatidylcholines (PCs) in aqueous dispersions have been studied experimentally (calorimetric and ultrasonic techniques) and theoretically (an Ising-like lattice model). The shape of the calorimetric curves was compared with the theoretical data and interpreted in terms of the lateral interactions and critical temperatures determined for each lipid studied. A critical chain length has been found (between 16 and 17 C-atoms per chain) which subdivides PCs into two classes with different phase behavior. In shorter lipids, the transition takes place above their critical temperatures meaning that this is an intrinsically continuous transition. In longer lipids, the transition occurs below the critical temperatures of the lipids, meaning that the transition is intrinsically discontinuous (first-order). This conclusion was supported independently by the ultrasonic relaxation sensitive to density fluctuations. Interestingly, it is this length that is the most abundant among the saturated chains in biological membranes.

  8. Well-defined block copolymers for gene delivery to dendritic cells: probing the effect of polycation chain-length.

    Science.gov (United States)

    Tang, Rupei; Palumbo, R Noelle; Nagarajan, Lakshmi; Krogstad, Emily; Wang, Chun

    2010-03-03

    The development of safe and efficient polymer carriers for DNA vaccine delivery requires mechanistic understanding of structure-function relationship of the polymer carriers and their interaction with antigen-presenting cells. Here we have synthesized a series of diblock copolymers with well-defined chain-length using atom transfer radical polymerization and characterized the influence of polycation chain-length on the physico-chemical properties of the polymer/DNA complexes as well as the interaction with dendritic cells. The copolymers consist of a hydrophilic poly(ethylene glycol) block and a cationic poly(aminoethyl methacrylate) (PAEM) block. The average degree of polymerization (DP) of the PAEM block was varied among 19, 39, and 75, with nearly uniform distribution. With increasing PAEM chain-length, polyplexes formed by the diblock copolymers and plasmid DNA had smaller average particle size and showed higher stability against electrostatic destabilization by salt and heparin. The polymers were not toxic to mouse dendritic cells (DCs) and only displayed chain-length-dependent toxicity at a high concentration (1mg/mL). In vitro gene transfection efficiency and polyplex uptake in DCs were also found to correlate with chain-length of the PAEM block with the longer polymer chain favoring transfection and cellular uptake. The polyplexes induced a modest up-regulation of surface markers for DC maturation that was not significantly dependent on PAEM chain-length. Finally, the polyplex prepared from the longest PAEM block (DP of 75) achieved an average of 20% enhancement over non-condensed anionic dextran in terms of uptake by DCs in the draining lymph nodes 24h after subcutaneous injection into mice. Insights gained from studying such structurally well-defined polymer carriers and their interaction with dendritic cells may contribute to improved design of practically useful DNA vaccine delivery systems. Copyright 2009 Elsevier B.V. All rights reserved.

  9. Spacer st4ructure

    International Nuclear Information System (INIS)

    Masetti, W.R.

    1978-01-01

    A spacer structure is described for maintaining a spaced relation between a plurality of generally parallel fuel rods within a housing in a nuclear reactor. The spacer structure is comprised of a grid pattern of ribs slotted to interlock with each other. The slots are arranged in such a way that when the ribs are welded to each other, the weld shrinkage is distributed uniformly in all directions to reduce or eliminate the amount of rework necessary in manufacturing the spacer structure

  10. Scaling behaviour of the correlation length for the two-point correlation function in the random field Ising chain

    Energy Technology Data Exchange (ETDEWEB)

    Lange, Adrian; Stinchcombe, Robin [Theoretical Physics, University of Oxford, Oxford (United Kingdom)

    1996-07-07

    We study the general behaviour of the correlation length {zeta}(kT:h) for two-point correlation function of the local fields in an Ising chain with binary distributed fields. At zero field it is shown that {zeta} is the same as the zero-field correlation length for the spin-spin correlation function. For the field-dominated behaviour of {zeta} we find an exponent for the power-law divergence which is smaller than the exponent for the spin-spin correlation length. The entire behaviour of the correlation length can be described by a single crossover scaling function involving the new critical exponent. (author)

  11. Fouling resistant membrane spacers

    KAUST Repository

    Ghaffour, Noreddine

    2017-10-12

    Disclosed herein are spacers having baffle designs and perforations for efficiently and effectively separating one or more membrane layers a membrane filtration system. The spacer (504) includes a body (524) formed at least in part by baffles (520) that are interconnected, and the baffles define boundaries of openings or apertures (525) through a thickness direction of the body of the spacer. Alternatively or additionally, passages or perforations (526A, 526B) may be present in the spacer layer or baffles for fluid flow there through, with the passages and baffles having a numerous different shapes and sizes.

  12. Mixing vane grid spacer

    International Nuclear Information System (INIS)

    Patterson, J.F.; Galbraith, K.P.

    1978-01-01

    An improved mixing vane grid spacer having enhanced flow mixing capability by virtue of mixing vanes being positioned at welded intersecting joints of the spacer wherein each mixing vane has an opening or window formed therein substantially directly over the welded joint to provide improved flow mixing capability is described. Some of the vanes are slotted, depending on their particular location in the spacers. The intersecting joints are welded by initially providing consumable tabs at and within each window, which are consumed during the welding of the spacer joints

  13. Control of in vivo disposition and immunogenicity of polymeric micelles by adjusting poly(sarcosine) chain lengths on surface

    Science.gov (United States)

    Kurihara, Kensuke; Ueda, Motoki; Hara, Isao; Ozeki, Eiichi; Togashi, Kaori; Kimura, Shunsaku

    2017-07-01

    Four kinds of A3B-type amphiphilic polydepsipeptides, (poly(sarcosine))3- b-poly( l-lactic acid) (the degree of polymerization of poly(sarcosine) are 10, 33, 55, and 85; S10 3 , S33 3 , S55 3 , and S85 3 ) were synthesized to prepare core-shell type polymeric micelles. Their in vivo dispositions and stimulations to trigger immune system to produce IgM upon multiple administrations to mice were examined. With increasing poly(sarcosine) chain lengths, the hydrophilic shell became thicker and the surface density at the most outer surface decreased on the basis of dynamic and static light scattering measurements. These two physical elements of polymeric micelles elicited opposite effects on the immune response in light of the chain length therefore to show an optimized poly(sarcosine) chain length existing between 33mer and 55mer to suppress the accelerated blood clearance phenomenon associated with polymeric micelles.

  14. On optimal length of hydrocarbon chain of fatty-acid collectors of rare earth ions

    International Nuclear Information System (INIS)

    Skrylev, L.D.; Sazonova, V.F.; Markina, Eh.L.

    1978-01-01

    The mechanism of the effect of the length of alkyl chain in fatty-acid collectors on the efficiency of flotation separation of the ions of rare earth elements (REE) collected by them has been investigated. REE flotation separation was studied on gadolinium chloride. Aqueous solutions of potassium caprinata, indecanate, laurate, tridecanate, myristate, pentadecanate and palmitate were used as collectors of Gd ions. The interaction of Gd ions with these compounds proceeds rapidly and is accompanied by stable colloidal solutions of Gd soaps being formed. Infrared spectra and radiograms of the sublates have been studied. It has been found that, with the number of carbon atoms in the collector molecule increasing from 10 to 16, the rate of flotation separation of Gd ions from solutions with pH 6 and 8 at first practically does not change (for potassium caprinate, undecanate and laurate), then drops sharply (potassium tridecanate and myristate), after which is again increases sharply (potassium pentadecanata and palmitate). The separation rate of Gd ions does not rise in solutions with pH 10. The nature of the sublate is shown to be determined by the solubility of the corresponing fatty acids and gadolinium soaps

  15. The interacting effects of temperature and food chain length on trophic abundance and ecosystem function.

    Science.gov (United States)

    Beveridge, Oliver S; Humphries, Stuart; Petchey, Owen L

    2010-05-01

    1. While much is known about the independent effects of trophic structure and temperature on density and ecosystem processes, less is known about the interaction(s) between the two. 2. We manipulated the temperature of laboratory-based bacteria-protist communities that contained communities with one, two, or three trophic levels, and recorded species' densities and bacterial decomposition. 3. Temperature, food chain length and their interaction produced significant responses in microbial density and bacterial decomposition. Prey and resource density expressed different patterns of temperature dependency during different phases of population dynamics. The addition of a predator altered the temperature-density relationship of prey, from a unimodal trend to a negative one. Bacterial decomposition was greatest in the presence of consumers at higher temperatures. 4. These results are qualitatively consistent with a recent model of direct and indirect temperature effects on resource-consumer population dynamics. Results highlight and reinforce the importance of indirect effects of temperature mediated through trophic interactions. Understanding and predicting the consequences of environmental change will require that indirect effects, trophic structure, and individual species' tolerances be incorporated into theory and models.

  16. Molecular identification of Giardia duodenalis in Ecuador by polymerase chain reaction-restriction fragment length polymorphism

    Directory of Open Access Journals (Sweden)

    Richard Atherton

    2013-06-01

    Full Text Available The aim of this study was to determine the genetic diversity of Giardia duodenalis present in a human population living in a northern Ecuadorian rain forest. All Giardia positive samples (based on an ELISA assay were analysed using a semi-nested polymerase chain reaction-restriction fragment length polymorphism assay that targets the glutamate dehydrogenase (gdh gene; those amplified were subsequently genotyped using NlaIV and RsaI enzymes. The gdh gene was successfully amplified in 74 of 154 ELISA positive samples; 69 of the 74 samples were subsequently genotyped. Of these 69 samples, 42 (61% were classified as assemblage B (26 as BIII and 16 as BIV, 22 (32% as assemblage A (3 as AI and 19 as AII and five (7% as mixed AII and BIII types. In this study site we observe similar diversity in genotypes to other regions in Latin America, though in contrast to some previous studies, we found similar levels of diarrheal symptoms in those individuals infected with assemblage B compared with those infected with assemblage A.

  17. Structural Stator Spacers

    DEFF Research Database (Denmark)

    Rasmussen, Peter Omand; Andreasen, Jens H.; Pijanowski, J. M.

    2001-01-01

    This paper presents a powerful new design aspect to reduce acoustic noise and vibration of electro-magnetic origin for electrical machines, by introducing improved slot wedges referred to as "Structural Stator Spacers". These spacers, by using a very stiff dielectric and non magnetic material...

  18. Chain length dependence of the helix orientation in Langmuir-Blodgett monolayers of alpha-helical diblock copolypeptides

    NARCIS (Netherlands)

    Nguyen, Le-Thu T.; Ardana, Aditya; Vorenkamp, Eltjo J.; ten Brinke, Gerrit; Schouten, Arend J.

    2010-01-01

    The effect of chain length on the helix orientation of alpha-helical diblock copolypeptides in Langmuir and Langmuir-Blodgett monolayers is reported for the first time. Amphiphilic diblock copolypeptides (PLGA-b-PMLGSLGs) of poly(alpha-L-glutamic acid) (PLGA) and

  19. Biosynthesis of Colabomycin E, a New Manumycin-Family Metabolite, Involves an Unusual Chain-Length Factor

    Czech Academy of Sciences Publication Activity Database

    Petříčková, Kateřina; Pospíšil, Stanislav; Kuzma, Marek; Tylová, Tereza; Jágr, Michal; Tomek, P.; Chroňáková, Alica; Brabcová, E.; Anděra, Ladislav; Krištůfek, Václav; Petříček, Miroslav

    2014-01-01

    Roč. 15, č. 9 (2014), s. 1334-1345 ISSN 1439-4227 R&D Projects: GA MZd(CZ) NT13012 Institutional support: RVO:61388971 ; RVO:60077344 ; RVO:68378050 Keywords : biosynthesis * chain-length factors * manumycins Subject RIV: CE - Biochemistry Impact factor: 3.088, year: 2014

  20. Development of environmentally friendly coatings and paints using medium-chain-length poly(3-hydroxyalkanoates) as the polymer binder

    NARCIS (Netherlands)

    Walle, van der G.A.M.; Buisman, F.J.H.; Weusthuis, R.A.; Eggink, G.

    1999-01-01

    Unsaturated medium-chain-length poly(3-hydroxyalkanoates) (mcl-PHAs) produced by Pseudomonas putida from linseed oil fatty acids (LOFA) and tall oil fatty acids (TOFA), were used as the polymer binder in the formulation of high solid alkyd-like paints. The relatively high concentration of

  1. Pseudomonas aeruginosa cytochrome c551 denaturation by five systematic urea derivatives that differ in the alkyl chain length.

    Science.gov (United States)

    Kobayashi, Shinya; Fujii, Sotaro; Koga, Aya; Wakai, Satoshi; Matubayasi, Nobuyuki; Sambongi, Yoshihiro

    2017-07-01

    Reversible denaturation of Pseudomonas aeruginosa cytochrome c 551 (PAc 551 ) could be followed using five systematic urea derivatives that differ in the alkyl chain length, i.e. urea, N-methylurea (MU), N-ethylurea (EU), N-propylurea (PU), and N-butylurea (BU). The BU concentration was the lowest required for the PAc 551 denaturation, those of PU, EU, MU, and urea being gradually higher. Furthermore, the accessible surface area difference upon PAc 551 denaturation caused by BU was found to be the highest, those by PU, EU, MU, and urea being gradually lower. These findings indicate that urea derivatives with longer alkyl chains are stronger denaturants. In this study, as many as five systematic urea derivatives could be applied for the reversible denaturation of a single protein, PAc 551 , for the first time, and the effects of the alkyl chain length on protein denaturation were systematically verified by means of thermodynamic parameters.

  2. Molecular dynamics simulation of radiation grafted FEP films as proton exchange membranes: Effects of the side chain length

    DEFF Research Database (Denmark)

    Li, Xue; Zhao, Yang; Li, Weiwei

    2017-01-01

    In order to study the microstructure of the prepared potential proton exchange membrane (PEM), molecular dynamics (MD) simulations were used to lucubrate the transport behavior of water molecules and hydronium ions inside the hydrated sulfonated styrene grafted fluorinated ethylene propylene (FEP...... whereas larger water clusters formed. The results of the mean square displacements (MSDs) show that the proton conductivities of the membranes with the proposed side chain lengths were about three fifths of the experimental data, of which the membrane with side chain length of 7 sulfonic styrene units...... was supposed to exhibit the highest proton conductivity, that is 115.69 mS cm-1. All of the supposed membrane models presented good proton conductivity that could definitely meet the application requirements of the proton exchange membranes. The MD simulations can provide an insight to the chain structure...

  3. Effects of cloud-point grafting, chain length, and density of PEG layers on competitive adsorption of ocular proteins

    DEFF Research Database (Denmark)

    Kingshott, P.; Thissen, H.; Griesser, H.J.

    2002-01-01

    The effects of pinning density, chain length, and 'cloud point' (CP) versus non-CP grafting conditions have been studied on the ability of polyethylene glycol (PEG) layers to minimize adsorption from a multicomponent (lysozyme, human serum albumin (HSA), IgG and lactoferrin) protein solution...... density) r.f.g.d. polymer layers. The PEG graft density was varied also by increasing the temperature and salt (K2SO4) content of the grafting solution; it reached a maximum at the CP of the PEGs. The CP reaction conditions were critical for producing PEG layers capable of minimizing protein adsorption. X...... density and chain length are interrelated, but the key factor is optimization of PEG chain density by use of the CP conditions, provided that a sufficient density of pinning sites exists. (C) 2002 Elsevier Science Ltd. Al l rights reserved....

  4. Dual influences of ecosystem size and disturbance on food chain length in streams.

    Science.gov (United States)

    McHugh, Peter A; McIntosh, Angus R; Jellyman, Phillip G

    2010-07-01

    The number of trophic transfers occurring between basal resources and top predators, food chain length (FCL), varies widely in the world's ecosystems for reasons that are poorly understood, particularly for stream ecosystems. Available evidence indicates that FCL is set by energetic constraints, environmental stochasticity, or ecosystem size effects, although no single explanation has yet accounted for FCL patterns in a broad sense. Further, whether environmental disturbance can influence FCL has been debated on both theoretical and empirical grounds for quite some time. Using data from sixteen South Island, New Zealand streams, we determined whether the so-called ecosystem size, disturbance, or resource availability hypotheses could account for FCL variation in high country fluvial environments. Stable isotope-based estimates of maximum trophic position ranged from 2.6 to 4.2 and averaged 3.5, a value on par with the global FCL average for streams. Model-selection results indicated that stream size and disturbance regime best explained across-site patterns in FCL, although resource availability was negatively correlated with our measure of disturbance; FCL approached its maximum in large, stable springs and was disturbed streams. Community data indicate that size influenced FCL, primarily through its influence on local fish species richness (i.e., via trophic level additions and/or insertions), whereas disturbance did so via an effect on the relative availability of intermediate predators (i.e., predatory invertebrates) as prey for fishes. Overall, our results demonstrate that disturbance can have an important food web-structuring role in stream ecosystems, and further imply that pluralistic explanations are needed to fully understand the range of structural variation observed for real food webs.

  5. Bat white-nose syndrome: a real-time TaqMan polymerase chain reaction test targeting the intergenic spacer region of Geomyces destructanstructans.

    Science.gov (United States)

    Muller, Laura K.; Lorch, Jeffrey M.; Lindner, Daniel L.; O'Connor, Michael; Gargas, Andrea; Blehert, David S.

    2013-01-01

    The fungus Geomyces destructans is the causative agent of white-nose syndrome (WNS), a disease that has killed millions of North American hibernating bats. We describe a real-time TaqMan PCR test that detects DNA from G. destructans by targeting a portion of the multicopy intergenic spacer region of the rRNA gene complex. The test is highly sensitive, consistently detecting as little as 3.3 fg of genomic DNA from G. destructans. The real-time PCR test specifically amplified genomic DNA from G. destructans but did not amplify target sequence from 54 closely related fungal isolates (including 43 Geomyces spp. isolates) associated with bats. The test was further qualified by analyzing DNA extracted from 91 bat wing skin samples, and PCR results matched histopathology findings. These data indicate the real-time TaqMan PCR method described herein is a sensitive, specific, and rapid test to detect DNA from G. destructans and provides a valuable tool for WNS diagnostics and research.

  6. Membrane with integrated spacer

    NARCIS (Netherlands)

    Balster, J.H.; Stamatialis, Dimitrios; Wessling, Matthias

    2010-01-01

    Many membrane processes are severely influenced by concentration polarisation. Turbulence promoting spacers placed in between the membranes can reduce the diffusional resistance of concentration polarisation by inducing additional mixing. Electrodialysis (ED) used for desalination suffers from

  7. Relationship between Length and Surface-Enhanced Raman Spectroscopy Signal Strength in Metal Nanoparticle Chains: Ideal Models versus Nanofabrication

    Directory of Open Access Journals (Sweden)

    Kristen D. Alexander

    2012-01-01

    Full Text Available We have employed capillary force deposition on ion beam patterned substrates to fabricate chains of 60 nm gold nanospheres ranging in length from 1 to 9 nanoparticles. Measurements of the surface-averaged SERS enhancement factor strength for these chains were then compared to the numerical predictions. The SERS enhancement conformed to theoretical predictions in the case of only a few chains, with the vast majority of chains tested not matching such behavior. Although all of the nanoparticle chains appear identical under electron microscope observation, the extreme sensitivity of the SERS enhancement to nanoscale morphology renders current nanofabrication methods insufficient for consistent production of coupled nanoparticle chains. Notwithstanding this fact, the aggregate data also confirmed that nanoparticle dimers offer a large improvement over the monomer enhancement while conclusively showing that, within the limitations imposed by current state-of-the-art nanofabrication techniques, chains comprising more than two nanoparticles provide only a marginal signal boost over the already considerable dimer enhancement.

  8. Association mapping of starch chain length distribution and amylose content in pea (Pisum sativum L.) using carbohydrate metabolism candidate genes.

    Science.gov (United States)

    Carpenter, Margaret A; Shaw, Martin; Cooper, Rebecca D; Frew, Tonya J; Butler, Ruth C; Murray, Sarah R; Moya, Leire; Coyne, Clarice J; Timmerman-Vaughan, Gail M

    2017-08-01

    Although starch consists of large macromolecules composed of glucose units linked by α-1,4-glycosidic linkages with α-1,6-glycosidic branchpoints, variation in starch structural and functional properties is found both within and between species. Interest in starch genetics is based on the importance of starch in food and industrial processes, with the potential of genetics to provide novel starches. The starch metabolic pathway is complex but has been characterized in diverse plant species, including pea. To understand how allelic variation in the pea starch metabolic pathway affects starch structure and percent amylose, partial sequences of 25 candidate genes were characterized for polymorphisms using a panel of 92 diverse pea lines. Variation in the percent amylose composition of extracted seed starch and (amylopectin) chain length distribution, one measure of starch structure, were characterized for these lines. Association mapping was undertaken to identify polymorphisms associated with the variation in starch chain length distribution and percent amylose, using a mixed linear model that incorporated population structure and kinship. Associations were found for polymorphisms in seven candidate genes plus Mendel's r locus (which conditions the round versus wrinkled seed phenotype). The genes with associated polymorphisms are involved in the substrate supply, chain elongation and branching stages of the pea carbohydrate and starch metabolic pathways. The association of polymorphisms in carbohydrate and starch metabolic genes with variation in amylopectin chain length distribution and percent amylose may help to guide manipulation of pea seed starch structural and functional properties through plant breeding.

  9. Soil pretreatment and fast cell lysis for direct polymerase chain reaction from forest soils for terminal restriction fragment length polymorphism analysis of fungal communities

    Directory of Open Access Journals (Sweden)

    Fei Cheng

    Full Text Available Abstract Humic substances in soil DNA samples can influence the assessment of microbial diversity and community composition. Using multiple steps during or after cell lysis adds expenses, is time-consuming, and causes DNA loss. A pretreatment of soil samples and a single step DNA extraction may improve experimental results. In order to optimize a protocol for obtaining high purity DNA from soil microbiota, five prewashing agents were compared in terms of their efficiency and effectiveness in removing soil contaminants. Residual contaminants were precipitated by adding 0.6 mL of 0.5 M CaCl2. Four cell lysis methods were applied to test their compatibility with the pretreatment (prewashing + Ca2+ flocculation and to ultimately identify the optimal cell lysis method for analyzing fungal communities in forest soils. The results showed that pretreatment with TNP + Triton X-100 + skim milk (100 mM Tris, 100 mM Na4P2O7, 1% polyvinylpyrrolidone, 100 mM NaCl, 0.05% Triton X-100, 4% skim milk, pH 10.0 removed most soil humic contaminants. When the pretreatment was combined with Ca2+ flocculation, the purity of all soil DNA samples was further improved. DNA samples obtained by the fast glass bead-beating method (MethodFGB had the highest purity. The resulting DNA was successfully used, without further purification steps, as a template for polymerase chain reaction targeting fungal internal transcribed spacer regions. The results obtained by terminal restriction fragment length polymorphism analysis indicated that the MethodFGB revealed greater fungal diversity and more distinctive community structure compared with the other methods tested. Our study provides a protocol for fungal cell lysis in soil, which is fast, convenient, and effective for analyzing fungal communities in forest soils.

  10. The effect of the chain length distribution of free fatty acids on the mixing properties of stratum corneum model membranes.

    Science.gov (United States)

    Oguri, Masashi; Gooris, Gert S; Bito, Kotatsu; Bouwstra, Joke A

    2014-07-01

    The stratum corneum (SC) plays a fundamental role in the barrier function of the skin. The SC consists of corneocytes embedded in a lipid matrix. The main lipid classes in the lipid matrix are ceramides (CERs), cholesterol (CHOL) and free fatty acids (FFAs). The aim of this study was to examine the effect of the chain length of FFAs on the thermotropic phase behavior and mixing properties of SC lipids. Fourier transform infrared spectroscopy and Raman imaging spectroscopy were used to study the mixing properties using either protonated or deuterated FFAs. We selected SC model lipid mixtures containing only a single CER, CHOL and either a single FFA or a mixture of FFAs mimicking the FFA SC composition. The single CER consists of a sphingoid base with 18 carbon atoms and an acyl chain with a chain length of 24 carbon atoms. When using lignoceric acid (24 carbon atoms) or a mixture of FFAs, the CER and FFAs participated in mixed crystals, but hydration of the mixtures induced a slight phase separation between CER and FFA. The mixed crystalline structures did not phase separate during storage even up to a time period of 3months. When using palmitic acid (16 carbon atoms), a slight phase separation was observed between FFA and CER. This phase separation was clearly enhanced during hydration and storage. In conclusion, the thermotropic phase behavior and the mixing properties of the SC lipid mixtures were shown to strongly depend on the chain length and chain length distribution of FFAs, while hydration enhanced the phase separation. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Proton conducting graft copolymers with tunable length and density of phosphonated side chains for fuel cell membranes

    DEFF Research Database (Denmark)

    Dimitrov, Ivaylo; Takamuku, Shogo; Jankova Atanasova, Katja

    2014-01-01

    Polysulfones functionalized with highly phosphonated poly(pentafluorostyrene) side chains of different lengths were synthesized applying controlled polymerization and modification methods. The graft copolymers' thermal properties were evaluated by differential scanning calorimetry and thermal...... gravimetrical analyses. The proton conductivity of membrane prepared from the graft copolymer with the shortest phosphonated side chains was 134 mS cm(-1) at 100 degrees C under fully immersed conditions. The graft copolymer TEM image shows a nanophase separation of ion-rich segments within the polysulfone...

  12. Development of environmentally friendly coatings and paints using medium-chain-length poly(3-hydroxyalkanoates) as the polymer binder.

    Science.gov (United States)

    van der Walle, G A; Buisman, G J; Weusthuis, R A; Eggink, G

    1999-01-01

    Unsaturated medium-chain-length poly(3-hydroxyalkanoates) (mcl-PHAs) produced by Pseudomonas putida from linseed oil fatty acids (LOFA) and tall oil fatty acids (TOFA), were used as the polymer binder in the formulation of high solid alkyd-like paints. The relatively high concentration of unsaturated alkyl side chains incorporated into the PHA resins resulted in oxidative drying PHA paints having excellent coating properties. The homogeneously pigmented PHA coatings yielded high-gloss, smooth and strong films upon curing and showed an excellent flexibility, a good adhesion to different substrates, cohesive film properties and resistance to chipping.

  13. σ-Bond Electron Delocalization in Oligosilanes as Function of Substitution Pattern, Chain Length, and Spatial Orientation

    Directory of Open Access Journals (Sweden)

    Johann Hlina

    2016-08-01

    Full Text Available Polysilanes are known to exhibit the interesting property of σ-bond electron delocalization. By employing optical spectroscopy (UV-vis, it is possible to judge the degree of delocalization and also differentiate parts of the molecules which are conjugated or not. The current study compares oligosilanes of similar chain length but different substitution pattern. The size of the substituents determines the spatial orientation of the main chain and also controls the conformational flexibility. The chemical nature of the substituents affects the orbital energies of the molecules and thus the positions of the absorption bands.

  14. The effect of the cation alkyl chain length on density and diffusion in dialkylpyrrolidinium bis(mandelato)borate ionic liquids.

    Science.gov (United States)

    Filippov, Andrei; Taher, Mamoun; Shah, Faiz Ullah; Glavatskih, Sergei; Antzutkin, Oleg N

    2014-12-28

    The physicochemical properties of ionic liquids are strongly affected by the selective combination of the cations and anions comprising the ionic liquid. In particular, the length of the alkyl chains of ions has a clear influence on the ionic liquid's performance. In this paper, we study the self-diffusion of ions in a series of halogen-free boron-based ionic liquids (hf-BILs) containing bis(mandelato)borate anions and dialkylpyrrolidinium cations with long alkyl chains CnH2n+1 with n from 4 to 14 within a temperature range of 293-373 K. It was found that the hf-BILs with n = 4-7 have very similar diffusion coefficients, while hf-BILs with n = 10-14 exhibit two liquid sub-phases in almost the entire temperature range studied (293-353 K). Both liquid sub-phases differ in their diffusion coefficients, while values of the slower diffusion coefficients are close to those of hf-BILs with shorter alkyl chains. To explain the particular dependence of diffusion on the alkyl chain length, we examined the densities of the hf-BILs studied here. It was shown that the dependence of the density on the number of CH2 groups in long alkyl chains of cations can be accurately described using a "mosaic type" model, where regions of long alkyl chains of cations (named 'aliphatic' regions) and the residual chemical moieties in both cations and anions (named 'ionic' regions) give additive contributions. Changes in density due to an increase in temperature and the number of CH2 groups in the long alkyl chains of cations are determined predominantly by changes in the free volume of the 'ionic' regions, while 'aliphatic' regions are already highly compressed by van der Waals forces, which results in only infinitesimal changes in their free volumes with temperature.

  15. Optimized Design of Spacer in Electrodialyzer Using CFD Simulation Method

    Science.gov (United States)

    Jia, Yuxiang; Yan, Chunsheng; Chen, Lijun; Hu, Yangdong

    2018-06-01

    In this study, the effects of length-width ratio and diversion trench of the spacer on the fluid flow behavior in an electrodialyzer have been investigated through CFD simulation method. The relevant information, including the pressure drop, velocity vector distribution and shear stress distribution, demonstrates the importance of optimized design of the spacer in an electrodialysis process. The results show width of the diversion trench has a great effect on the fluid flow compared with length. Increase of the diversion trench width could strength the fluid flow, but also increase the pressure drop. Secondly, the dead zone of the fluid flow decreases with increase of length-width ratio of the spacer, but the pressure drop increases with the increase of length-width ratio of the spacer. So the appropriate length-width ratio of the space should be moderate.

  16. Effect of side chain length on the stability and structural properties of 3

    African Journals Online (AJOL)

    thiophene (DOOPT) and their dimers studied by Hartree-Fock (HF) and Density Functional Theory (DFT) methods. The DFT calculations suggest that dimers of the dialkoxyphenylthiophenes with longer side chains are thermodynamically more ...

  17. Effect of Difference in Fatty Acid Chain Lengths of Medium- Chain Lipids on Lipid/Surfactant/Water Phase Diagrams and Drug Solubility

    Directory of Open Access Journals (Sweden)

    Hetal N. Prajapati

    2011-09-01

    Full Text Available Lipids consisting of medium chain fatty acids are commonly used in the development of lipid-based selfemulsifying and self-microemulsifying drug delivery systems. However, no systematic approach to selecting one lipid over another has been reported in the literature. In this study, propylene glycol (PG monoester (PG monocaprylate, Capmul PG-8® and PG diester (PG dicaprylocaprate, Captex 200P® of C8-fatty acids were compared with PG monoester (PG monolaurate, Capmul PG-12® and PG diester (PG dilaurate, Capmul PG-2L® of C12-fatty acids with respect to their phase diagrams, and especially for their ability to form microemulsions in the presence of a common surfactant, Cremophor EL®, and water. The solubility of two model drugs, danazol and probucol, in the lipids and lipid/surfactant mixtures were also compared. The effect of the chain length of medium-chain fatty acids (C8 versus C12 on the phase diagrams of the lipids was minimal. Both shorter and longer chain lipids formed essentially similar microemulsion and emulsion regions in the presence of Cremophor EL® and water, although the C12-fatty acid esters formed larger gel regions in the phase diagrams than the C8-fatty acid esters. When monoesters were mixed with their respective diesters at 1:1 ratios, larger microemulsion regions with lower lipid particle sizes were observed compared to those obtained with individual lipids alone. While the solubility of both danazol and probucol increased greatly in all lipids studied, compared to their aqueous solubility, the solubility in C12-fatty acid esters was found to be lower than in C8-fatty acid esters when the lipids were used alone. This difference in solubility due to the difference in fatty acid chain length, practically disappeared when the lipids were combined with the surfactant.

  18. Anomaly in the Chain Length Dependence of n-Alkane Diffusion in ZIF-4 Metal-Organic Frameworks

    Directory of Open Access Journals (Sweden)

    Seungtaik Hwang

    2018-03-01

    Full Text Available Molecular diffusion is commonly found to slow down with increasing molecular size. Deviations from this pattern occur in some host materials with pore sizes approaching the diameters of the guest molecules. A variety of theoretical models have been suggested to explain deviations from this pattern, but robust experimental data are scarcely available. Here, we present such data, obtained by monitoring the chain length dependence of the uptake of n-alkanes in the zeolitic imidazolate framework ZIF-4. A monotonic decrease in diffusivity from ethane to n-butane was observed, followed by an increase for n-pentane, and another decrease for n-hexane. This observation was confirmed by uptake measurements with n-butane/n-pentane mixtures, which yield faster uptake of n-pentane. Further evidence is provided by the observation of overshooting effects, i.e., by transient n-pentane concentrations exceeding the (eventually attained equilibrium value. Accompanying grand canonical Monte Carlo simulations reveal, for the larger n-alkanes, significant differences between the adsorbed and gas phase molecular configurations, indicating strong confinement effects within ZIF-4, which, with increasing chain length, may be expected to give rise to configurational shifts facilitating molecular propagation at particular chain lengths.

  19. Anomaly in the Chain Length Dependence of n-Alkane Diffusion in ZIF-4 Metal-Organic Frameworks.

    Science.gov (United States)

    Hwang, Seungtaik; Gopalan, Arun; Hovestadt, Maximilian; Piepenbreier, Frank; Chmelik, Christian; Hartmann, Martin; Snurr, Randall Q; Kärger, Jörg

    2018-03-15

    Molecular diffusion is commonly found to slow down with increasing molecular size. Deviations from this pattern occur in some host materials with pore sizes approaching the diameters of the guest molecules. A variety of theoretical models have been suggested to explain deviations from this pattern, but robust experimental data are scarcely available. Here, we present such data, obtained by monitoring the chain length dependence of the uptake of n- alkanes in the zeolitic imidazolate framework ZIF-4. A monotonic decrease in diffusivity from ethane to n- butane was observed, followed by an increase for n- pentane, and another decrease for n- hexane. This observation was confirmed by uptake measurements with n- butane/ n -pentane mixtures, which yield faster uptake of n- pentane. Further evidence is provided by the observation of overshooting effects, i.e., by transient n- pentane concentrations exceeding the (eventually attained) equilibrium value. Accompanying grand canonical Monte Carlo simulations reveal, for the larger n- alkanes, significant differences between the adsorbed and gas phase molecular configurations, indicating strong confinement effects within ZIF-4, which, with increasing chain length, may be expected to give rise to configurational shifts facilitating molecular propagation at particular chain lengths.

  20. Self-consistent field theoretic simulations of amphiphilic triblock copolymer solutions: Polymer concentration and chain length effects

    Directory of Open Access Journals (Sweden)

    X.-G. Han

    2014-06-01

    Full Text Available Using the self-consistent field lattice model, polymer concentration φP and chain length N (keeping the length ratio of hydrophobic to hydrophilic blocks constant the effects on temperature-dependent behavior of micelles are studied, in amphiphilic symmetric ABA triblock copolymer solutions. When chain length is increased, at fixed φP, micelles occur at higher temperature. The variations of average volume fraction of stickers φcos and the lattice site numbers Ncols at the micellar cores with temperature are dependent on N and φP, which demonstrates that the aggregation of micelles depends on N and φP. Moreover, when φP is increased, firstly a peak appears on the curve of specific heat CV for unimer-micelle transition, and then in addition a primary peak, the secondary peak, which results from the remicellization, is observed on the curve of CV. For a long chain, in intermediate and high concentration regimes, the shape of specific heat peak markedly changes, and the peak tends to be a more broad peak. Finally, the aggregation behavior of micelles is explained by the aggregation way of amphiphilic triblock copolymer. The obtained results are helpful in understanding the micellar aggregation process.

  1. Impact of the alkyl chain length on binding of imidazolium-based ionic liquids to bovine serum albumin

    Science.gov (United States)

    Zhang, Mengyue; Wang, Ying; Zhang, Hongmei; Cao, Jian; Fei, Zhenghao; Wang, Yanqing

    2018-05-01

    The effects of six imidazolium-based ionic liquids (ILs) with different alkyl chain length ([CnMim]Cl, n = 2, 4, 6, 8, 10, 12) on the structure and functions of bovine serum albumin (BSA) were studied by multi-spectral methods and molecular docking. ILs with the longer alkyl chain length have the stronger binding interaction with BSA and the greater conformational damage to protein. The effects of ILs on the functional properties of BSA were further studied by the determination of non-enzyme esterase activity, β-fibrosis and other properties of BSA. The thermal stability of BSA was reduced, the rate of the formation of beta sheet structures of BSA was lowered, and the esterase-like activity of BSA were decreased with the increase of ILs concentration. Simultaneous molecular modeling technique revealed the favorable binding sites of ILs on protein. The hydrophobic force and polar interactions were the mainly binding forces of them. The calculated results are in a good agreement with the spectroscopic experiments. These studies on the impact of the alkyl chain length on binding of imidazolium-based ionic liquids to BSA are of great significance for understanding and developing the application of ionic liquid in life and physiological system.

  2. Phase Behavior and Evaporation Profile of Tween 20 - Eugenol System. Effect of Different Alkane Chain Length and Solvent System

    International Nuclear Information System (INIS)

    Kassim, A.; Lim, W.H.; Kuangl, D.; Rusmawati, W.W.M.; Abdullah, A.H.; Teoh, S.P.

    2003-01-01

    The isotropic region of Tween 20/eugenol/n-alkane in aqueous systems was determined. The solubilisation trend of isotropic solution formed in the presence of eugenol was studied as a function of different alkyl chain length of n-alkane. The solubility of solvent in surfactant solution is dependent on their molecular polarity. An increase in n-alkane chain length (lower polarity) lead to smaller isotropic region which will affect the surfactant partitioning between the interface, the oil phase and the aqueous phase of the microemulsion as the oil chain length is varied. The changes of evaporation behaviour were affected strongly by the types of phases existed in the systems. The increment of n-alkane and water content led to higher evaporation rate. But the formation of w/o microemulsion would lower the evaporation rate because water molecules were trapped in the core of aggregates. In solubilisation system, evaporation rate is dependent on the solvent content and the interaction between Tween 20 and solvent molecules in the mixed composition. (author)

  3. Spectral sensitization of TiO2 by new hemicyanine dyes in dye solar cell yielding enhanced photovoltage: Probing chain length effect on performance

    International Nuclear Information System (INIS)

    Fadadu, Kishan B.; Soni, Saurabh S.

    2013-01-01

    Graphical abstract: New hemicyanine dyes based on indolenine moiety were utilized as light harvesting materials in dye sensitized solar cell. Chain lengths of the molecules were varied in order to study its effect of chain length on the performance of DSSC. Electron transfer kinetic of the solar cell was studied and it was found that the chain length changes the electron transfer kinetic. We have achieved remarkable photovoltage and overall performance of DSSC. Highlights: ► New hemicyanine dyes based on indolenine moiety were utilized as light harvesting materials in dye sensitized solar cell. ► Chain lengths of the molecules were varied in order to study its effect of chain length on the performance of DSSC. ► Electron transfer kinetic of the solar cell was studied and it was found that the chain length changes the electron transfer kinetic. -- Abstract: New hemicyanine dyes having indole nucleus with different alkyl chain length were synthesized and characterized using 1 H NMR and mass spectroscopy. These dyes were used to sensitize the TiO 2 film in dye sensitized solar cell. Nanocrystalline dye solar cells were fabricated and characterized using various electrochemical techniques. It has been found that the alkyl chain length present in the dye molecules greatly affects the overall performance of dye solar cell. Molecules having longer alkyl chain are having better sensitizers which enhance V oc to significant extent. Chain length dependent performance was further investigated using Tafel polarization and impedance method. Hemicyanine dye having hexyl chain has outperformed by attaining 2.9% solar to electricity conversion efficiency

  4. Thermoresponsive Poly(2-oxazoline) Molecular Brushes by Living Ionic Polymerization: Kinetic Investigations of Pendant Chain Grafting and Cloud Point Modulation by Backbone and Side Chain Length Variation

    KAUST Repository

    Zhang, Ning

    2012-04-17

    Molecular brushes of poly(2-oxazoline)s were prepared by living anionic polymerization of 2-iso-propenyl-2-oxazoline to form the backbone and subsequent living cationic ring-opening polymerization of 2-n- or 2-iso-propyl-2-oxazoline for pendant chain grafting. In situ kinetic studies indicate that the initiation efficiency and polymerization rates are independent from the number of initiator functions per initiator molecule. This was attributed to the high efficiency of oxazolinium salt and the stretched conformation of the backbone, which is caused by the electrostatic repulsion of the oxazolinium moieties along the macroinitiator. The resulting molecular brushes showed thermoresponsive properties, that is, having a defined cloud point (CP). The dependence of the CP as a function of backbone and side chain length as well as concentration was studied. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Simulated glass-forming polymer melts: dynamic scattering functions, chain length effects, and mode-coupling theory analysis.

    Science.gov (United States)

    Frey, S; Weysser, F; Meyer, H; Farago, J; Fuchs, M; Baschnagel, J

    2015-02-01

    We present molecular-dynamics simulations for a fully flexible model of polymer melts with different chain length N ranging from short oligomers (N = 4) to values near the entanglement length (N = 64). For these systems we explore the structural relaxation of the supercooled melt near the critical temperature T c of mode-coupling theory (MCT). Coherent and incoherent scattering functions are analyzed in terms of the idealized MCT. For temperatures T > T c we provide evidence for the space-time factorization property of the β relaxation and for the time-temperature superposition principle (TTSP) of the α relaxation, and we also discuss deviations from these predictions for T ≈ T c. For T larger than the smallest temperature where the TTSP holds we perform a quantitative analysis of the dynamics with the asymptotic MCT predictions for the late β regime. Within MCT a key quantity, in addition to T c, is the exponent parameter λ. For the fully flexible polymer models studied we find that λ is independent of N and has a value (λ = 0.735 ) typical of simple glass-forming liquids. On the other hand, the critical temperature increases with chain length toward an asymptotic value T c (∞) . This increase can be described by T c (∞) - T c(N) ∼ 1/N and may be interpreted in terms of the N dependence of the monomer density ρ, if we assume that the MCT glass transition is ruled by a soft-sphere-like constant coupling parameter Γ c = ρ c T c (-1/4), where ρ c is the monomer density at T c. In addition, we also estimate T c from a Hansen-Verlet-like criterion and MCT calculations based on structural input from the simulation. For our polymer model both the Hansen-Verlet criterion and the MCT calculations suggest T c to decrease with increasing chain length, in contrast to the direct analysis of the simulation data.

  6. Novel Strategies for Production of Medium and High Chain Length Alcohols

    NARCIS (Netherlands)

    Lopez Contreras, A.M.; Kuit, W.; Springer, J.; Claassen, P.A.M.

    2011-01-01

    Fermentation-derived ethanol is currently widely used as transport fuel, both as such or as a blending component in gasoline (Antoni et al. 2007; Mielenz 2001). However, longer chain alcohols have higher energy densities and are less soluble in water than ethanol, which are important advantages for

  7. Ion solvation in polymer blends and block copolymer melts: effects of chain length and connectivity on the reorganization of dipoles.

    Science.gov (United States)

    Nakamura, Issei

    2014-05-29

    We studied the thermodynamic properties of ion solvation in polymer blends and block copolymer melts and developed a dipolar self-consistent field theory for polymer mixtures. Our theory accounts for the chain connectivity of polymerized monomers, the compressibility of the liquid mixtures under electrostriction, the permanent and induced dipole moments of monomers, and the resultant dielectric contrast among species. In our coarse-grained model, dipoles are attached to the monomers and allowed to rotate freely in response to electrostatic fields. We demonstrate that a strong electrostatic field near an ion reorganizes dipolar monomers, resulting in nonmonotonic changes in the volume fraction profile and the dielectric function of the polymers with respect to those of simple liquid mixtures. For the parameter sets used, the spatial variations near an ion can be in the range of 1 nm or larger, producing significant differences in the solvation energy among simple liquid mixtures, polymer blends, and block copolymers. The solvation energy of an ion depends substantially on the chain length in block copolymers; thus, our theory predicts the preferential solvation of ions arising from differences in chain length.

  8. Effects of chain length, chlorination degree, and structure on the octanol-water partition coefficients of polychlorinated n-alkanes.

    Science.gov (United States)

    Hilger, Bettina; Fromme, Hermann; Völkel, Wolfgang; Coelhan, Mehmet

    2011-04-01

    Log octanol-water partition coefficients (log Kow) of 40 synthesized polychlorinated n-alkanes (PCAs) with different chlorination degrees were determined using reversed-phase high performance liquid chromatography (RP-HPLC). In addition, log Kow values of a technical mixture namely Cereclor 63L as well as 15 individual in house synthesized C10, C11, and C12 chloroalkanes with known chlorine positions were estimated. Based on these results, the effects of chain length, chlorination degree, and structure were explored. The estimated log Kow values ranged from 4.10 (polychlorinated n-decanes with 50.2% chlorine content) to 11.34 (polychlorinated n-octacosanes with 54.8% chlorine content) for PCAs and from 3.82 (1,2,5,6,9,10-hexachlorodecane) to 7.75 (1,1,1,3,9,11,11,11-octachlorododecane) for the individual chloroalkanes studied. The results showed that log Kow value was influenced linearly at a given chlorine content by chain length, while a polynominal effect was observed in dependence on the chlorination degree of an alkane chain. Chlorine substitution pattern influenced markedly the log Kow value of chloroalkanes.

  9. The effect of the alkyl chain length on physicochemical features of (ionic liquids + γ-butyrolactone) binary mixtures

    International Nuclear Information System (INIS)

    Papović, Snežana; Bešter-Rogač, Marija; Vraneš, Milan; Gadžurić, Slobodan

    2016-01-01

    Highlights: • Influence of alkyl substituent length on IL properties was studied. • Nature of interactions between studied [C_nC_1im][NTf_2] and GBL were discussed. • Angell strength parameter indicates [C_nC_1im][NTf_2] are fragile liquids. • ILs properties regularly change with increase of the alkyl chain length. • Absence of GBL self-association upon addition of IL is observed. - Abstract: Densities and viscosities were determined and analysed for γ-butyrolactone (GBL) binary mixtures with 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids (where alkyl = ethyl, hexyl, octyl) as a function of temperature at atmospheric pressure (p = 0.1 MPa) and over the whole composition range. Excess molar volumes have been calculated from the experimental densities and were fitted using Redlich–Kister’s polynomial equation. Other volumetric parameters have been also calculated in order to obtain information about interactions between GBL and imidazolium based ionic liquids with different alkyl chain length. From the viscosity measurements, the Angell strength parameter was calculated for pure ionic liquids indicating that all investigated electrolytes are “fragile” liquids.

  10. Electrical contacts to nanorod networks at different length scales: From macroscale ensembles to single nanorod chains

    KAUST Repository

    Lavieville, Romain; Zhang, Yang; Di Fabrizio, Enzo M.; Krahne, Roman

    2013-01-01

    The nature of metal-semiconductor interfaces at the nanoscale is an important issue in micro- and nanoelectronic engineering. The study of charge transport through chains of CdSe semiconductor nanorods linked by Au particles represents an ideal model system for this matter, because the metal semiconductor interface is an intrinsic feature of the nanosystem. Here we show the controlled fabrication of all-inorganic hybrid metal-semiconductor networks with different size, in which the semiconductor nanorods are linked by Au domains at their tips. We demonstrate different approaches to selectively contact the networks and single nanorod chains with planar electrodes, and we investigate their charge transport at room temperature. © 2013 Elsevier B.V. All rights reserved.

  11. Electrical contacts to nanorod networks at different length scales: From macroscale ensembles to single nanorod chains

    KAUST Repository

    Lavieville, Romain

    2013-11-01

    The nature of metal-semiconductor interfaces at the nanoscale is an important issue in micro- and nanoelectronic engineering. The study of charge transport through chains of CdSe semiconductor nanorods linked by Au particles represents an ideal model system for this matter, because the metal semiconductor interface is an intrinsic feature of the nanosystem. Here we show the controlled fabrication of all-inorganic hybrid metal-semiconductor networks with different size, in which the semiconductor nanorods are linked by Au domains at their tips. We demonstrate different approaches to selectively contact the networks and single nanorod chains with planar electrodes, and we investigate their charge transport at room temperature. © 2013 Elsevier B.V. All rights reserved.

  12. Room temperature ionic liquids: A simple model. Effect of chain length and size of intermolecular potential on critical temperature.

    Science.gov (United States)

    Chapela, Gustavo A; Guzmán, Orlando; Díaz-Herrera, Enrique; del Río, Fernando

    2015-04-21

    A model of a room temperature ionic liquid can be represented as an ion attached to an aliphatic chain mixed with a counter ion. The simple model used in this work is based on a short rigid tangent square well chain with an ion, represented by a hard sphere interacting with a Yukawa potential at the head of the chain, mixed with a counter ion represented as well by a hard sphere interacting with a Yukawa potential of the opposite sign. The length of the chain and the depth of the intermolecular forces are investigated in order to understand which of these factors are responsible for the lowering of the critical temperature. It is the large difference between the ionic and the dispersion potentials which explains this lowering of the critical temperature. Calculation of liquid-vapor equilibrium orthobaric curves is used to estimate the critical points of the model. Vapor pressures are used to obtain an estimate of the triple point of the different models in order to calculate the span of temperatures where they remain a liquid. Surface tensions and interfacial thicknesses are also reported.

  13. Synthesis, Characterization and Biological Studies of New Linear Thermally Stable Schiff Base Polymers with Flexible Spacers.

    Science.gov (United States)

    Qureshi, Farah; Khuhawar, Muhammad Yar; Jahangir, Taj Muhammad; Channar, Abdul Hamid

    2016-01-01

    Five new linear Schiff base polymers having azomethine structures, ether linkages and extended aliphatic chain lengths with flexible spacers were synthesized by polycondensation of dialdehyde (monomer) with aliphatic and aromatic diamines. The formation yields of monomer and polymers were obtained within 75-92%. The polymers with flexible spacers of n-hexane were somewhat soluble in acetone, chloroform, THF, DMF and DMSO on heating. The monomer and polymers were characterized by melting point, elemental microanalysis, FT-IR, (1)HNMR, UV-Vis spectroscopy, thermogravimetry (TG), differential thermal analysis (DTA), fluorescence emission, scanning electron microscopy (SEM) and viscosities and thermodynamic parameters measurements of their dilute solutions. The studies supported formation of the monomer and polymers and on the basis of these studies their structures have been assigned. The synthesized polymers were tested for their antibacterial and antifungal activities.

  14. Esterification of fatty acids using nylon-immobilized lipase in n-hexane: kinetic parameters and chain-length effects.

    Science.gov (United States)

    Zaidi, A; Gainer, J L; Carta, G; Mrani, A; Kadiri, T; Belarbi, Y; Mir, A

    2002-02-28

    The esterification of long-chain fatty acids in n-hexane catalyzed by nylon-immobilized lipase from Candida rugosa has been investigated. Butyl oleate (22 carbon atoms), oleyl butyrate (22 carbon atoms) and oleyl oleate (36 carbon atoms) were produced at maximum reaction rates of approximately equal to 60 mmol h(-1) g(-1) immobilized enzyme when the substrates were present in equimolar proportions at an initial concentration of 0.6 mol l(-1). The observed kinetic behavior of all the esterification reactions is found to follow a ping-pong bi-bi mechanism with competitive inhibition by both substrates. The effect of the chain-length of the fatty acids and the alcohols could be correlated to some mechanistic models, in accordance with the calculated kinetic parameters.

  15. Immobilization of lipases on alkyl silane modified magnetic nanoparticles: effect of alkyl chain length on enzyme activity.

    Directory of Open Access Journals (Sweden)

    Jiqian Wang

    Full Text Available BACKGROUND: Biocatalytic processes often require a full recycling of biocatalysts to optimize economic benefits and minimize waste disposal. Immobilization of biocatalysts onto particulate carriers has been widely explored as an option to meet these requirements. However, surface properties often affect the amount of biocatalysts immobilized, their bioactivity and stability, hampering their wide applications. The aim of this work is to explore how immobilization of lipases onto magnetite nanoparticles affects their biocatalytic performance under carefully controlled surface modification. METHODOLOGY/PRINCIPAL FINDINGS: Magnetite nanoparticles, prepared through a co-precipitation method, were coated with alkyl silanes of different alkyl chain lengths to modulate their surface hydrophobicity. Candida rugosa lipase was then directly immobilized onto the modified nanoparticles through hydrophobic interaction. Enzyme activity was assessed by catalytic hydrolysis of p-nitrophenyl acetate. The activity of immobilized lipases was found to increase with increasing chain length of the alkyl silane. Furthermore, the catalytic activities of lipases immobilized on trimethoxyl octadecyl silane (C18 modified Fe(3O(4 were a factor of 2 or more than the values reported from other surface immobilized systems. After 7 recycles, the activities of the lipases immobilized on C18 modified nanoparticles retained 65%, indicating significant enhancement of stability as well through hydrophobic interaction. Lipase immobilized magnetic nanoparticles facilitated easy separation and recycling with high activity retaining. CONCLUSIONS/SIGNIFICANCE: The activity of immobilized lipases increased with increasing alkyl chain length of the alkyl trimethoxy silanes used in the surface modification of magnetite nanoparticles. Lipase stability was also improved through hydrophobic interaction. Alkyl silane modified magnetite nanoparticles are thus highly attractive carriers for

  16. Immobilization of lipases on alkyl silane modified magnetic nanoparticles: effect of alkyl chain length on enzyme activity.

    Science.gov (United States)

    Wang, Jiqian; Meng, Gang; Tao, Kai; Feng, Min; Zhao, Xiubo; Li, Zhen; Xu, Hai; Xia, Daohong; Lu, Jian R

    2012-01-01

    Biocatalytic processes often require a full recycling of biocatalysts to optimize economic benefits and minimize waste disposal. Immobilization of biocatalysts onto particulate carriers has been widely explored as an option to meet these requirements. However, surface properties often affect the amount of biocatalysts immobilized, their bioactivity and stability, hampering their wide applications. The aim of this work is to explore how immobilization of lipases onto magnetite nanoparticles affects their biocatalytic performance under carefully controlled surface modification. Magnetite nanoparticles, prepared through a co-precipitation method, were coated with alkyl silanes of different alkyl chain lengths to modulate their surface hydrophobicity. Candida rugosa lipase was then directly immobilized onto the modified nanoparticles through hydrophobic interaction. Enzyme activity was assessed by catalytic hydrolysis of p-nitrophenyl acetate. The activity of immobilized lipases was found to increase with increasing chain length of the alkyl silane. Furthermore, the catalytic activities of lipases immobilized on trimethoxyl octadecyl silane (C18) modified Fe(3)O(4) were a factor of 2 or more than the values reported from other surface immobilized systems. After 7 recycles, the activities of the lipases immobilized on C18 modified nanoparticles retained 65%, indicating significant enhancement of stability as well through hydrophobic interaction. Lipase immobilized magnetic nanoparticles facilitated easy separation and recycling with high activity retaining. The activity of immobilized lipases increased with increasing alkyl chain length of the alkyl trimethoxy silanes used in the surface modification of magnetite nanoparticles. Lipase stability was also improved through hydrophobic interaction. Alkyl silane modified magnetite nanoparticles are thus highly attractive carriers for enzyme immobilization enabling efficient enzyme recovery and recycling.

  17. Collapse of Langmuir monolayer at lower surface pressure: Effect of hydrophobic chain length

    Energy Technology Data Exchange (ETDEWEB)

    Das, Kaushik, E-mail: kaushikdas2089@gmail.com; Kundu, Sarathi [Physical Sciences Division, Institute of Advanced Study in Science and Technology, Vigyan Path, Paschim Boragaon, Garchuk, Guwahati, Assam 781035 (India)

    2016-05-23

    Long chain fatty acid molecules (e.g., stearic and behenic acids) form a monolayer on water surface in the presence of Ba{sup 2+} ions at low subphase pH (≈ 5.5) and remain as a monolayer before collapse generally occurs at higher surface pressure (π{sub c} > 50 mN/m). Monolayer formation is verified from the surface pressure vs. area per molecule (π-A) isotherms and also from the atomic force microscopy (AFM) analysis of the films deposited by single upstroke of hydrophilic Si (001) substrate through the monolayer covered water surface. At high subphase pH (≈ 9.5), barium stearate molecules form multilayer structure at lower surface pressure which is verified from the π-A isotherms and AFM analysis of the film deposited at 25 mN/m. Such monolayer to multilayer structure formation or monolayer collapse at lower surface pressure is unusual as at this surface pressure generally fatty acid salt molecules form a monolayer on the water surface. Formation of bidentate chelate coordination in the metal containing headgroups is the reason for such monolayer to multilayer transition. However, for longer chain barium behenate molecules only monolayer structure is maintained at that high subphase pH (≈ 9.5) due to the presence of relatively more tail-tail hydrophobic interaction.

  18. Fuel assembly spacer

    International Nuclear Information System (INIS)

    Shirakawa, Ken-etsu.

    1988-01-01

    Purpose: To reduce the pressure loss of coolants by fuel assembly spacers. Constitution: Spacers for supporting a fuel assembly are attached by means of a plurality of wires to an outer frame. The outer frame is made of shape memory alloy such that the wires are caused to slacken at normal temperature and the slacking of the wires is eliminated in excess of the transition temperature. Since the wires slacken at the normal temperature, fuel rods can be inserted easily. After the insertion of the fuel rods, when the entire portion or the outer frame is heated by water or gas at a predetermined temperature, the outer frame resumes its previously memorized shape to tighten the wires and, accordingly, the fuel rods can be supported firmly. In this way, since the fuel rods are inserted in the slacken state of the wires and, after the assembling, the outer frame resumes its memorized shape, the assembling work can be conducted efficiently. (Kamimura, M.)

  19. Effect of bidispersity in grafted chain length on grafted chain conformations and potential of mean force between polymer grafted nanoparticles in a homopolymer matrix.

    Science.gov (United States)

    Nair, Nitish; Wentzel, Nathaniel; Jayaraman, Arthi

    2011-05-21

    In efforts to produce polymeric materials with tailored physical properties, significant interest has grown around the ability to control the spatial organization of nanoparticles in polymer nanocomposites. One way to achieve controlled particle arrangement is by grafting the nanoparticle surface with polymers that are compatible with the matrix, thus manipulating the interfacial interactions between the nanoparticles and the polymer matrix. Previous work has shown that the molecular weight of the grafted polymer, both at high grafting density and low grafting density, plays a key role in dictating the effective inter-particle interactions in a polymer matrix. At high grafting density nanoparticles disperse (aggregate) if the graft molecular weight is higher (lower) than the matrix molecular weight. At low grafting density the longer grafts can better shield the nanoparticle surface from direct particle-particle contacts than the shorter grafts and lead to the dispersion of the grafted particles in the matrix. Despite the importance of graft molecular weight, and evidence of non-trivial effects of polydispersity of chains grafted on flat surfaces, most theoretical work on polymer grafted nanoparticles has only focused on monodisperse grafted chains. In this paper, we focus on how bidispersity in grafted chain lengths affects the grafted chain conformations and inter-particle interactions in an implicit solvent and in a dense homopolymer polymer matrix. We first present the effects of bidispersity on grafted chain conformations in a single polymer grafted particle using purely Monte Carlo (MC) simulations. This is followed by calculations of the potential of mean force (PMF) between two grafted particles in a polymer matrix using a self-consistent Polymer Reference Interaction Site Model theory-Monte Carlo simulation approach. Monte Carlo simulations of a single polymer grafted particle in an implicit solvent show that in the bidisperse polymer grafted particles

  20. Antiaromatic bisindeno-[n]thienoacenes with small singlet biradical characters: Syntheses, structures and chain length dependent physical properties

    KAUST Repository

    Shi, Xueliang

    2014-01-01

    Recent studies demonstrated that aromaticity and biradical character play important roles in determining the ground-state structures and physical properties of quinoidal polycyclic hydrocarbons and oligothiophenes, a kind of molecular materials showing promising applications for organic electronics, photonics and spintronics. In this work, we designed and synthesized a new type of hybrid system, the so-called bisindeno-[n]thienoacenes (n = 1-4), by annulation of quinoidal fused α-oligothiophenes with two indene units. The obtained molecules can be regarded as antiaromatic systems containing 4n π electrons with small singlet biradical character (y0). Their ground-state geometry and electronic structures were studied by X-ray crystallographic analysis, NMR, ESR and Raman spectroscopy, assisted by density functional theory calculations. With extension of the chain length, the molecules showed a gradual increase of the singlet biradical character accompanied by decreased antiaromaticity, finally leading to a highly reactive bisindeno[4]thienoacene (S4-TIPS) which has a singlet biradical ground state (y0= 0.202). Their optical and electronic properties in the neutral and charged states were systematically investigated by one-photon absorption, two-photon absorption, transient absorption spectroscopy, cyclic voltammetry and spectroelectrochemistry, which could be correlated to the chain length dependent antiaromaticity and biradical character. Our detailed studies revealed a clear structure-aromaticity-biradical character-physical properties-reactivity relationship, which is of importance for tailored material design in the future. This journal is

  1. Evaluation of clay hybrid nanocomposites of different chain length as reinforcing agent for natural and synthetic rubbers

    International Nuclear Information System (INIS)

    Yehia, A.A.; Akelah, A.M.; Rehab, A.; El-Sabbagh, S.H.; El Nashar, D.E.; Koriem, A.A.

    2012-01-01

    Highlights: → The modified organo-clay (MMT-ATBN) markedly reinforce natural and synthetic rubbers. → The reinforcing efficiency of the organo-clay is much higher than HAF carbon black. → The reinforcing efficiency of MMT modified with different alkylamines greatly depend on the chain length. → The good compatibility of modified organo-clay with NBR can be attributed to the chemical nature. -- Abstract: Polymer nanocomposites are one of the highly discussed research topics in recent time. It has been reported in the present paper the preparation and the properties of different nanoclays based on sodium montmorillonite (bentonite) and some organic amines of varying chain lengths (dodecylamine, hexadecylamine and octadecylamine) beside amine-terminated butadiene-acrylonitrile copolymer (ATBN). The hybrid clays have been characterized with the help of Fourier Transform Infrared spectroscopy (FTIR). Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Wide angle X-ray diffractions (WXRD), and Thermogravimetric analysis (TGA). X-ray results showed that the intergallery distance of the clay is increased as a result of the intercalation of the amines and ATBN. The nanocomposite clays were incorporated in natural and synthetic rubbers (NR, SBR and NBR). The physico-mechanical properties are greatly improved with loading low concentrations of the nanocomposite clays compared with carbon black.

  2. Dynamic photoinduced realignment processes in photoresponsive block copolymer films: effects of the chain length and block copolymer architecture.

    Science.gov (United States)

    Sano, Masami; Shan, Feng; Hara, Mitsuo; Nagano, Shusaku; Shinohara, Yuya; Amemiya, Yoshiyuki; Seki, Takahiro

    2015-08-07

    A series of block copolymers composed of an amorphous poly(butyl methacrylate) (PBMA) block connected with an azobenzene (Az)-containing liquid crystalline (PAz) block were synthesized by changing the chain length and polymer architecture. With these block copolymer films, the dynamic realignment process of microphase separated (MPS) cylinder arrays of PBMA in the PAz matrix induced by irradiation with linearly polarized light was studied by UV-visible absorption spectroscopy, and time-resolved grazing incidence small angle X-ray scattering (GI-SAXS) measurements using a synchrotron beam. Unexpectedly, the change in the chain length hardly affected the realignment rate. In contrast, the architecture of the AB-type diblock or the ABA-type triblock essentially altered the realignment feature. The strongly cooperative motion with an induction period before realignment was characteristic only for the diblock copolymer series, and the LPL-induced alignment change immediately started for triblock copolymers and the PAz homopolymer. Additionally, a marked acceleration in the photoinduced dynamic motions was unveiled in comparison with a thermal randomization process.

  3. Effect of side chain length and degree of polymerization on the decomposition and crystallization behaviour of chlorinated poly(vinyl ester) oligomers

    International Nuclear Information System (INIS)

    Heinze, D.; Mang, Th.; Popescu, C.; Weichold, O.

    2016-01-01

    Highlights: • Thermal behaviour of telomerized polyvinyl esters is investigated. • Thermal stability relies mainly on the contribution of side chains. • At equal molecular weights thermal stability is dictated by length of side chain. • Increasing the length of side chains improves also the packing degree of polymer. - Abstract: Four members of a homologous series of chlorinated poly(vinyl ester) oligomers CCl_3–(CH_2CH (OCO(CH_2)_mCH_3))_n–Cl with degrees of polymerization of 10 and 20 were prepared by telomerisation using carbon tetrachloride. The number of side chain carbon atoms ranges from 2 (poly(vinyl acetate) to 18 (poly(vinyl stearate)). The effect of the n-alkyl side chain length and of the degree of polymerization on the thermal stability and crystallization behaviour of the synthesized compounds was investigated. All oligomers degrade in two major steps by first losing HCl and side chains with subsequent breakdown of the backbone. The members with short side chains, up to poly(vinyl octanoate), are amorphous and show internal plasticization, whereas those with high number of side chain carbon atoms are semi-crystalline due to side-chain crystallization. A better packing for poly(vinyl stearate) is also noticeable. The glass transition and melting temperatures as well as the onset temperature of decomposition are influenced to a larger extent by the side chain length than by the degree of polymerization. Thermal stability is improved if both the size and number of side chains increase, but only a long side chain causes a significant increase of the resistance to degradation. This results in a stabilization of PVAc so that oligomers from poly(vinyl octanoate) on are stable under atmospheric conditions. Thus, the way to design stable, chlorinated PVEs oligomers is to use a long n-alkyl side chain.

  4. Effect of side chain length and degree of polymerization on the decomposition and crystallization behaviour of chlorinated poly(vinyl ester) oligomers

    Energy Technology Data Exchange (ETDEWEB)

    Heinze, D.; Mang, Th. [Aachen University of Applied Sciences, Heinrich-Mussmann-Str. 1, 52428 Jülich (Germany); Popescu, C., E-mail: crisan.popescu@kao.com [KAO Germany GmbH, Pfungstädterstr. 98-100, 64297 Darmstadt (Germany); Weichold, O., E-mail: weichold@ibac.rwth-aachen.de [Institute of Building Materials Research, Schinkelstr. 3, 52062 Aachen (Germany)

    2016-08-10

    Highlights: • Thermal behaviour of telomerized polyvinyl esters is investigated. • Thermal stability relies mainly on the contribution of side chains. • At equal molecular weights thermal stability is dictated by length of side chain. • Increasing the length of side chains improves also the packing degree of polymer. - Abstract: Four members of a homologous series of chlorinated poly(vinyl ester) oligomers CCl{sub 3}–(CH{sub 2}CH (OCO(CH{sub 2}){sub m}CH{sub 3})){sub n}–Cl with degrees of polymerization of 10 and 20 were prepared by telomerisation using carbon tetrachloride. The number of side chain carbon atoms ranges from 2 (poly(vinyl acetate) to 18 (poly(vinyl stearate)). The effect of the n-alkyl side chain length and of the degree of polymerization on the thermal stability and crystallization behaviour of the synthesized compounds was investigated. All oligomers degrade in two major steps by first losing HCl and side chains with subsequent breakdown of the backbone. The members with short side chains, up to poly(vinyl octanoate), are amorphous and show internal plasticization, whereas those with high number of side chain carbon atoms are semi-crystalline due to side-chain crystallization. A better packing for poly(vinyl stearate) is also noticeable. The glass transition and melting temperatures as well as the onset temperature of decomposition are influenced to a larger extent by the side chain length than by the degree of polymerization. Thermal stability is improved if both the size and number of side chains increase, but only a long side chain causes a significant increase of the resistance to degradation. This results in a stabilization of PVAc so that oligomers from poly(vinyl octanoate) on are stable under atmospheric conditions. Thus, the way to design stable, chlorinated PVEs oligomers is to use a long n-alkyl side chain.

  5. Effects of Chain Length and Saturability of Fatty Acids on Phospholipids and Proteins in Plasma Membranes of Bovine Mammary Gland.

    Science.gov (United States)

    Yan, Qiongxian; Tang, Shaoxun; Han, Xuefeng; Bamikole, Musibau Adungbe; Zhou, Chuanshe; Kang, Jinhe; Wang, Min; Tan, Zhiliang

    2016-12-01

    Free fatty acids (FFAs) in plasma are essential substrates for de novo synthesis of milk fat, or directly import into mammary cells. The physico-chemical properties of mammary cells membrane composition affected by FFAs with different chain lengths and saturability are unclear yet. Employing GC, FTIR and fluorescence spectroscopy, the adsorption capacity, phospholipids content, membrane proteins conformation, lipid peroxidation product, and free sulfhydryl of plasma membranes (PMs) interacted with different FFAs were determined. The mammary cells PMs at 38 and 39.5 °C showed different adsorption capacities: acetic acid (Ac) > stearic acid (SA) > β-hydroxybutyric acid (BHBA) > trans10, cis12 CLA. In the FTIR spectrum, the major adsorption peaks appeared at 2920 and 2850 cm -1 for phospholipids, and at 1628 and 1560 cm -1 for membrane proteins. The intensities of PMs-FFAs complexes were varied with the FFAs species and their initial concentrations. The β-sheet and turn structures of membrane proteins were transferred into random coil and α-helix after BHBA, SA and trans10, cis12 CLA treatments compared with Ac treatment. The quenching effects on the fluorescence of endogenous membrane protein, 1, 8-ANS, NBD-PE, and DHPE entrapped in PMs by LCFA were different from those of short chain FFAs. These results indicate that the adsorption of FFAs could change membrane protein conformation and polarity of head group in phospholipids. This variation of the mammary cells PMs was regulated by carbon chain length and saturability of FFAs.

  6. 4-N, 4-S & 4-O Chloroquine Analogues: Influence of Side Chain Length and Quinolyl Nitrogen pKa on Activity vs. Chloroquine Resistant Malaria+, #

    OpenAIRE

    Natarajan, Jayakumar K.; Alumasa, John; Yearick, Kimberly; Ekoue-Kovi, Kekeli A.; Casabianca, Leah B.; de Dios, Angel C.; Wolf, Christian; Roepe, Paul D.

    2008-01-01

    Using predictions from heme – quinoline antimalarial complex structures, previous modifications of chloroquine (CQ), and hypotheses for chloroquine resistance (CQR), we synthesize and assay CQ analogues that test structure – function principles. We vary side chain length for both monoethyl and diethyl 4N CQ derivatives. We alter the pKa of the quinolyl N by introducing alkylthio or alkoxy substituents into the 4 position, and vary side chain length for these analogues. We introduce an additio...

  7. Effects of alkyl chain length and solvents on thermodynamic dissociation constants of the ionic liquids with one carboxyl group in the alkyl chain of imidazolium cations.

    Science.gov (United States)

    Chen, Yuehua; Wang, Huiyong; Wang, Jianji

    2014-05-01

    Thermodynamic dissociation constants of the Brønsted acidic ionic liquids (ILs) are important for their catalytic and separation applications. In this work, a series of imidazolium bromides with one carboxylic acid substitute group in their alkyl chain ([{(CH2)nCOOH}mim]Br, n = 1,3,5,7) have been synthesized, and their dissociation constants (pKa) at different ionic strengths have been determined in aqueous and aqueous organic solvents at 0.1 mole fraction (x) of ethanol, glycol, iso-propanol, and dimethyl sulfoxide by potentiometric titrations at 298.2 K. The standard thermodynamic dissociation constants (pKa(T)) of the ILs in these solvents were calculated from the extended Debye-Hückel equation. It was found that the pKa values increased with the increase of ionic strength of the media and of the addition of organic solvent in water. The pKa(T) values also increased with the increase of the alkyl chain length of cations of the ILs. In addition, the effect of solvent nature on pKa(T) values is interpreted from solvation of the dissociation components and their Gibbs energy of transfer from water to aqueous organic solutions.

  8. Application of nitrogen and carbon stable isotopes (δ(15N and δ(13C to quantify food chain length and trophic structure.

    Directory of Open Access Journals (Sweden)

    Matthew J Perkins

    Full Text Available Increasingly, stable isotope ratios of nitrogen (δ(15N and carbon (δ(13C are used to quantify trophic structure, though relatively few studies have tested accuracy of isotopic structural measures. For laboratory-raised and wild-collected plant-invertebrate food chains spanning four trophic levels we estimated nitrogen range (NR using δ(15N, and carbon range (CR using δ(13C, which are used to quantify food chain length and breadth of trophic resources respectively. Across a range of known food chain lengths we examined how NR and CR changed within and between food chains. Our isotopic estimates of structure are robust because they were calculated using resampling procedures that propagate variance in sample means through to quantified uncertainty in final estimates. To identify origins of uncertainty in estimates of NR and CR, we additionally examined variation in discrimination (which is change in δ(15N or δ(13C from source to consumer between trophic levels and among food chains. δ(15N discrimination showed significant enrichment, while variation in enrichment was species and system specific, ranged broadly (1.4‰ to 3.3‰, and importantly, propagated variation to subsequent estimates of NR. However, NR proved robust to such variation and distinguished food chain length well, though some overlap between longer food chains infers a need for awareness of such limitations. δ(13C discrimination was inconsistent; generally no change or small significant enrichment was observed. Consequently, estimates of CR changed little with increasing food chain length, showing the potential utility of δ(13C as a tracer of energy pathways. This study serves as a robust test of isotopic quantification of food chain structure, and given global estimates of aquatic food chains approximate four trophic levels while many food chains include invertebrates, our use of four trophic level plant-invertebrate food chains makes our findings relevant for a majority

  9. Application of Nitrogen and Carbon Stable Isotopes (δ15N and δ13C) to Quantify Food Chain Length and Trophic Structure

    Science.gov (United States)

    Perkins, Matthew J.; McDonald, Robbie A.; van Veen, F. J. Frank; Kelly, Simon D.; Rees, Gareth; Bearhop, Stuart

    2014-01-01

    Increasingly, stable isotope ratios of nitrogen (δ15N) and carbon (δ13C) are used to quantify trophic structure, though relatively few studies have tested accuracy of isotopic structural measures. For laboratory-raised and wild-collected plant-invertebrate food chains spanning four trophic levels we estimated nitrogen range (NR) using δ15N, and carbon range (CR) using δ13C, which are used to quantify food chain length and breadth of trophic resources respectively. Across a range of known food chain lengths we examined how NR and CR changed within and between food chains. Our isotopic estimates of structure are robust because they were calculated using resampling procedures that propagate variance in sample means through to quantified uncertainty in final estimates. To identify origins of uncertainty in estimates of NR and CR, we additionally examined variation in discrimination (which is change in δ15N or δ13C from source to consumer) between trophic levels and among food chains. δ15N discrimination showed significant enrichment, while variation in enrichment was species and system specific, ranged broadly (1.4‰ to 3.3‰), and importantly, propagated variation to subsequent estimates of NR. However, NR proved robust to such variation and distinguished food chain length well, though some overlap between longer food chains infers a need for awareness of such limitations. δ13C discrimination was inconsistent; generally no change or small significant enrichment was observed. Consequently, estimates of CR changed little with increasing food chain length, showing the potential utility of δ13C as a tracer of energy pathways. This study serves as a robust test of isotopic quantification of food chain structure, and given global estimates of aquatic food chains approximate four trophic levels while many food chains include invertebrates, our use of four trophic level plant-invertebrate food chains makes our findings relevant for a majority of ecological systems

  10. Application of nitrogen and carbon stable isotopes (δ(15)N and δ(13)C) to quantify food chain length and trophic structure.

    Science.gov (United States)

    Perkins, Matthew J; McDonald, Robbie A; van Veen, F J Frank; Kelly, Simon D; Rees, Gareth; Bearhop, Stuart

    2014-01-01

    Increasingly, stable isotope ratios of nitrogen (δ(15)N) and carbon (δ(13)C) are used to quantify trophic structure, though relatively few studies have tested accuracy of isotopic structural measures. For laboratory-raised and wild-collected plant-invertebrate food chains spanning four trophic levels we estimated nitrogen range (NR) using δ(15)N, and carbon range (CR) using δ(13)C, which are used to quantify food chain length and breadth of trophic resources respectively. Across a range of known food chain lengths we examined how NR and CR changed within and between food chains. Our isotopic estimates of structure are robust because they were calculated using resampling procedures that propagate variance in sample means through to quantified uncertainty in final estimates. To identify origins of uncertainty in estimates of NR and CR, we additionally examined variation in discrimination (which is change in δ(15)N or δ(13)C from source to consumer) between trophic levels and among food chains. δ(15)N discrimination showed significant enrichment, while variation in enrichment was species and system specific, ranged broadly (1.4‰ to 3.3‰), and importantly, propagated variation to subsequent estimates of NR. However, NR proved robust to such variation and distinguished food chain length well, though some overlap between longer food chains infers a need for awareness of such limitations. δ(13)C discrimination was inconsistent; generally no change or small significant enrichment was observed. Consequently, estimates of CR changed little with increasing food chain length, showing the potential utility of δ(13)C as a tracer of energy pathways. This study serves as a robust test of isotopic quantification of food chain structure, and given global estimates of aquatic food chains approximate four trophic levels while many food chains include invertebrates, our use of four trophic level plant-invertebrate food chains makes our findings relevant for a majority of

  11. PEGylation of Phytantriol-Based Lyotropic Liquid Crystalline Particles-The Effect of Lipid Composition, PEG Chain Length, and Temperature on the Internal Nanostructure

    DEFF Research Database (Denmark)

    Nilsson, Christa; Ostergaard, Jesper; Larsen, Susan Weng

    2014-01-01

    of these lipidic nonlamellar liquid crystalline particles by using DSPE-mPEGs with three different block lengths of the hydrophilic PEG segment. The effects of lipid composition, PEG chain length, and temperature on the morphology and internal nanostructure of these self-assembled lipidic aqueous dispersions based...

  12. Effect of Hydrophobic Chain Length on the Stability and Guest Exchange Behavior of Shell-Sheddable Micelles Formed by Disulfide-Linked Diblock Copolymers.

    Science.gov (United States)

    Fan, Haiyan; Li, Yixia; Yang, Jinxian; Ye, Xiaodong

    2017-10-19

    Reduction-responsive micelles hold enormous promise for application as drug carriers due to the fast drug release triggered by reducing conditions and high anticancer activity. However, the effect of hydrophobic chain length on the stability and guest exchange of reduction-responsive micelles, especially for the micelles formed by diblock copolymers containing single disulfide group, is not fully understood. Here, shell-sheddable micelles formed by a series of disulfide-linked copolymer poly(ethylene glycol)-b-poly(ε-caprolactone) (PEG-SS-PCL) containing the same chain length of PEG but different chain lengths of hydrophobic block PCL were prepared and well characterized. The influence of the chain length of hydrophobic PCL block on the stability and guest exchange of PEG-SS-PCL micelles was studied by the use of both dynamic laser light scattering (DLS) and fluorescence resonance energy transfer (FRET). The results show that longer PCL chains lead to a slower aggregation rate and guest exchange of micelles in the aqueous solutions containing 10 mM dithiothreitol (DTT). The cell uptake of the shell-sheddable PEG-SS-PCL micelles in vitro shows that the amount of internalization of dyes loaded in PEG-SS-PCL micelles increases with the chain length of hydrophobic PCL block investigated by flow cytometric analysis and confocal fluorescence microscopy.

  13. HLA-DPB1 typing with polymerase chain reaction and restriction fragment length polymorphism technique in Danes

    DEFF Research Database (Denmark)

    Hviid, Thomas Vauvert F.; Madsen, Hans O; Morling, Niels

    1992-01-01

    We have used the polymerase chain reaction (PCR) in combination with the restriction fragment length polymorphism (RFLP) technique for HLA-DBP1 typing. After PCR amplification of the polymorphic second exon of the HLA-DPB1 locus, the PCR product was digested with seven allele-specific restriction...... endonucleases: RsaI, FokI, ApaI, SacI, BstUI, EcoNI, and DdeI, and the DNA fragments were separated by electrophoresis in agarose gels. Altogether, 71 individuals were investigated and 16 different HLA-DPB1 types were observed in 26 different heterozygotic combinations, as well as five possible homozygotes....... Four heterozygotes could not be unequivocally typed with the PCR-RFLP method. The HLA-DPB1 typing results obtained with the PCR-RFLP method were compared with the typing results obtained with PCR allele-specific oligonucleotides (PCR-ASO) in 50 individuals. The results obtained with the two methods...

  14. Modulation of saturation and chain length of fatty acids in Saccharomyces cerevisiae for production of cocoa butter-like lipids

    DEFF Research Database (Denmark)

    Bergenholm, David; Gossing, Michael; Wei, Yongjun

    2018-01-01

    Chain length and degree of saturation plays an important role for the characteristics of various products derived from fatty acids, such as fuels, cosmetics, and food additives. The seeds of Theobroma cacao are the source of cocoa butter, a natural lipid of high interest for the food and cosmetics...... as the saturated fatty acid stearic acid is typically found only in low abundance. Demand for cocoa butter is increasing, yet T. cacao can only be cultivated in some parts of the tropics. Alternative means of production of cocoa butter lipids (CBLs) are, therefore, sought after. Yeasts also store fatty acids...... industry. Cocoa butter is rich in saturated fatty acids that are stored in the form of triacylglycerides (TAGs). One of the major TAG species of cocoa butter, consisting of two stearic acid molecules and one oleic acid molecule (stearic acid-oleic acid-stearic acid, sn-SOS), is particularly rare in nature...

  15. A kinetic model for growth and biosynthesis of medium-chain-length poly-(3-hydroxyalkanoates in Pseudomonas putida

    Directory of Open Access Journals (Sweden)

    M. S. M. Annuar

    2008-06-01

    Full Text Available A kinetic model is presented giving a mathematical description of batch culture of Pseudomonas putida PGA1 grown using saponified palm kernel oil as carbon source and ammonium as the limiting nutrient. The growth of the micro-organism is well-described using Tessier-type model which takes into account the inhibitory effect of ammonium at high concentrations. The ammonium consumption rate by the cells is related in proportion to the rate of growth. The intracellular production of medium-chain-length poly-(3-hydroxyalkanoates (PHA MCL by P. putida PGA1 cells is reasonably modeled by the modified Luedeking-Piret kinetics, which incorporate a function of product synthesis inhibition (or reduction by ammonium above a threshold level.

  16. The Relationship between the Monomer Chain Length and the Electro-Optical Properties of Polymer Dispersed Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Liu J.

    2016-03-01

    Full Text Available Five polymers dispersed liquid crystalline (LC films were fabricated using photo-polymerizable monomers with different lengths of carbon chains. These LC films have shown different electro-optical (EO properties. Through their SEM pictures, the relationship between the linear electro-optical effect and the mesh size of the polymer network was explored. With the increase of number of photo-polymerizable monomers, the mesh size of the polymer network would become larger. So the liquid crystal molecules would be easily oriented in the electric field and therefore, the threshold voltage and saturation voltage would decrease. The open state response times were also reduced and the off state response times would be extended. The DFT simulations have shown principal role of the ground state dipole moments in the observed electro-optical efficiency.

  17. Production of Medium Chain Length Polyhydroxyalkanoates From Oleic Acid Using Pseudomonas putida PGA1 by Fed Batch Culture

    Directory of Open Access Journals (Sweden)

    Sidik Marsudi

    2010-10-01

    Full Text Available Bacterial polyhydroxyalkanoates (PHAs are a class of p0lymers currently receiving much attention because of their potential as renewable and biodegradable plastics. A wide variety of bacteria has been reported to produce PHAs including Pseudomonas strains. These strains are known as versatile medium chain length PHAs (PHAs-mcl producers using fatty acids as carbon source. Oleic acid was used to produce PHAs-mcl using Pseudomonas putida PGA 1 by continuous feeding of both nitrogen and carbon source, in a fed batch culture. During cell growth, PHAs also accumulated, indicating that PHA production in this organism is growth associated. Residual cell increased until the nitrogen source was depleted. At the end of fermentation, final cell concentration, PHA content, and roductivity were 30.2 g/L, 44.8 % of cell dry weight, and 0.188 g/l/h, respectively.

  18. Synthesis of Medium-Chain-Length Polyhydroxyalkanoate Homopolymers, Random Copolymers, and Block Copolymers by an Engineered Strain of Pseudomonas entomophila.

    Science.gov (United States)

    Wang, Ying; Chung, Ahleum; Chen, Guo-Qiang

    2017-04-01

    Medium-chain-length polyhydroxyalkanoates (mcl-PHAs), widely used in medical area, are commonly synthesized by Pseudomonas spp. This study tries to use β-oxidation pathways engineered P. entomophila to achieve single source of a series of mcl-monomers for microbial production of PHA homopolymers. The effort is proven successful for the first time to obtain a wide range of mcl-PHA homopolymers from engineered P. entomophila LAC23 grown on various fatty acids, respectively, ranging from poly(3-hydroxyheptanoate) to poly(3-hydroxytetradecanoate). Effects of a PHA monomer chain length on thermal and crystallization properties including the changes of T m , T g , and T d5% are investigated. Additionally, strain LAC23 is used to synthesize random copolymers of 3-hydroxyoctanoate (3HO) and 3-hydroxydodecanoate (3HDD) or 3-hydroxytetradecanoates, their compositions could be controlled by adjusting the ratios of two related fatty acids. Meanwhile, block copolymer P(3HO)-b-P(3HDD) is synthesized by the same strain. It is found for the first time that even- and odd number mcl-PHA homopolymers have different physical properties. When the gene of the PHA synthase in the engineered P. entomophila is replaced by phaC from Aeromonas hydrophila 4AK4, poly(3-hydroxybutyrate-co-30 mol%-3-hydroxyhexanoate) is synthesized. Therefore, P. entomophila can be used to synthesize the whole range of PHA (C7-C14) homopolymers, random- and block copolymers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Interaction and dynamics of (alkylamide + electrolyte) deep eutectics: Dependence on alkyl chain-length, temperature, and anion identity

    International Nuclear Information System (INIS)

    Guchhait, Biswajit; Das, Suman; Daschakraborty, Snehasis; Biswas, Ranjit

    2014-01-01

    Here we investigate the solute-medium interaction and solute-centered dynamics in (RCONH 2 + LiX) deep eutectics (DEs) via carrying out time-resolved fluorescence measurements and all-atom molecular dynamics simulations at various temperatures. Alkylamides (RCONH 2 ) considered are acetamide (CH 3 CONH 2 ), propionamide (CH 3 CH 2 CONH 2 ), and butyramide (CH 3 CH 2 CH 2 CONH 2 ); the electrolytes (LiX) are lithium perchlorate (LiClO 4 ), lithium bromide (LiBr), and lithium nitrate (LiNO 3 ). Differential scanning calorimetric measurements reveal glass transition temperatures (T g ) of these DEs are ∼195 K and show a very weak dependence on alkyl chain-length and electrolyte identity. Time-resolved and steady state fluorescence measurements with these DEs have been carried out at six-to-nine different temperatures that are ∼100–150 K above their individual T g s. Four different solute probes providing a good spread of fluorescence lifetimes have been employed in steady state measurements, revealing strong excitation wavelength dependence of probe fluorescence emission peak frequencies. Extent of this dependence, which shows sensitivity to anion identity, has been found to increase with increase of amide chain-length and decrease of probe lifetime. Time-resolved measurements reveal strong fractional power dependence of average rates for solute solvation and rotation with fraction power being relatively smaller (stronger viscosity decoupling) for DEs containing longer amide and larger (weaker decoupling) for DEs containing perchlorate anion. Representative all-atom molecular dynamics simulations of (CH 3 CONH 2 + LiX) DEs at different temperatures reveal strongly stretched exponential relaxation of wavevector dependent acetamide self dynamic structure factor with time constants dependent both on ion identity and temperature, providing justification for explaining the fluorescence results in terms of temporal heterogeneity and amide clustering in these multi

  20. Influence of alkyl chain length and temperature on thermophysical properties of ammonium-based ionic liquids with molecular solvent.

    Science.gov (United States)

    Kavitha, T; Attri, Pankaj; Venkatesu, Pannuru; Devi, R S Rama; Hofman, T

    2012-04-19

    Mixing of ionic liquids (ILs) with molecular solvent can expand the range of structural properties and the scope of molecular interactions between the molecules of the solvents. Exploiting of these phenomena essentially require a basic fundamental understanding of mixing behavior of ILs with molecular solvents. In this context, a series of protic ILs possessing tetra-alkyl ammonium cation [R(4)N](+) with commonly used anion hydroxide [OH](-) were synthesized and characterized by temperature dependent thermophysical properties. The ILs [R(4)N](+)[OH](-) are varying only in the length of alkyl chain (R is methyl, ethyl, propyl, or butyl) of tetra-alkyl ammonium on the cationic part. The ILs used for the present study included tetramethyl ammonium hydroxide [(CH(3))(4)N](+)[OH](-) (TMAH), tetraethyl ammonium hydroxide [(C(2)H(5))(4)N](+)[OH](-) (TEAH), tetrapropyl ammonium hydroxide [(C(3)H(7))(4)N](+)[OH](-) (TPAH) and tetrabutyl ammonium hydroxide [(C(4)H(9))(4)N](+)[OH](-) (TBAH). The alkyl chain length effect has been analyzed by precise measurements such as densities (ρ), ultrasonic sound velocity (u), and viscosity (η) of these ILs with polar solvent, N-methyl-2-pyrrolidone (NMP), over the full composition range as a function of temperature. The excess molar volume (V(E)), the deviation in isentropic compressibility (Δκ(s)) and deviation in viscosity (Δη) were predicted using these properties as a function of the concentration of ILs. Redlich-Kister polynomial was used to correlate the results. A qualitative analysis of the results is discussed in terms of the ion-dipole, ion-pair interactions, and hydrogen bonding between ILs and NMP molecules. Later, the hydrogen bonding features between ILs and NMP were also analyzed using a molecular modeling program with the help of HyperChem 7.

  1. Effect of the number, position and length of alkyl chains on the physical properties of polysubstituted pyridinium ionic liquids

    International Nuclear Information System (INIS)

    Verdía, Pedro; Hernaiz, Marta; González, Emilio J.; Macedo, Eugénia A.; Salgado, Josefa; Tojo, Emilia

    2014-01-01

    Highlights: • Synthesis of five polysubstituted pyridinium based-ionic liquids. • Physical properties of the pure ionic liquids were measured at several temperatures. • Thermal analysis of the pure ionic liquids was carried out by DSC and TGA techniques. • Density, speed of sound, and refractive index were fitted with a linear expression. • Viscosity data were correlated using the VFT equation. -- Abstract: The knowledge of the physical properties of ionic liquids is of high importance in order to evaluate their potential applicability for a given purpose. In the last few years, ionic liquids have been proposed as promising solvents for extractive desulfurization of fuels. Among them, recent studies have shown that ionic liquids derived from pyridinium affords excellent S-compounds removal capacity. In this work, the thermal analysis of five ionic liquids derived from pyridinium cation polysubstituted with different alkyl chains was carried out by Differencial Scanning Calorimetry (DSC) and Thermal Gravimetric Analysis (TGA). Furthermore, the density, speed of sound, refractive index and dynamic viscosity for all the pure ionic liquids were also measured from T = (298.15 to 343.15) K. The effect of the number of cation alkyl chains, their length, and their position on the pyridinium ring, on the ionic liquid physical properties is also analyzed and discussed

  2. Increased mean aliphatic lipid chain length in left ventricular hypertrophy secondary to arterial hypertension: A cross-sectional study.

    Science.gov (United States)

    Evaristi, Maria Francesca; Caubère, Céline; Harmancey, Romain; Desmoulin, Franck; Peacock, William Frank; Berry, Matthieu; Turkieh, Annie; Barutaut, Manon; Galinier, Michel; Dambrin, Camille; Polidori, Carlo; Miceli, Cristina; Chamontin, Bernard; Koukoui, François; Roncalli, Jerôme; Massabuau, Pierre; Smih, Fatima; Rouet, Philippe

    2016-11-01

    About 77.9 million (1 in 4) American adults have high blood pressure. High blood pressure is the primary cause of left ventricular hypertrophy (LVH), which represents a strong predictor of future heart failure and cardiovascular mortality. Previous studies have shown an altered metabolic profile in hypertensive patients with LVH. The goal of this study was to identify blood metabolomic LVH biomarkers by H NMR to provide novel diagnostic tools for rapid LVH detection in populations of hypertensive individuals. This cross-sectional study included 48 hypertensive patients with LVH matched with 48 hypertensive patients with normal LV size, and 24 healthy controls. Two-dimensional targeted M-mode echocardiography was performed to measure left ventricular mass index. Partial least squares discriminant analysis was used for the multivariate analysis of the H NMR spectral data. From the H NMR-based metabolomic profiling, signals coming from methylene (-CH2-) and methyl (-CH3) moieties of aliphatic chains from plasma lipids were identified as discriminant variables. The -CH2-/-CH3 ratio, an indicator of the mean length of the aliphatic lipid chains, was significantly higher (P hypertensive group without LVH and controls. Receiver operating characteristic curve showed that a cutoff of 2.34 provided a 52.08% sensitivity and 85.42% specificity for discriminating LVH (AUC = 0.703, P-value hypertension.

  3. Fatty acid biosynthesis VII. Substrate control of chain-length of products synthesised by rat liver fatty acid synthetase

    DEFF Research Database (Denmark)

    Hansen, Heinz Johs. Max; Carey, E.M.; Dils, R.

    1970-01-01

    - 1. Gas-liquid and paper chromatography have been used to determine the chain-lengths of fatty acids synthesised by purified rat liver fatty acid synthetase from [1-14C]acetyl-CoA, [1,3-14C2]malonyl-CoA and from [1-14C]acetyl-CoA plus partially purified rat liver acetyl-CoA carboxylase. - 2....... A wide range (C4:0–C18:0) of fatty acids was synthesised and the proportions were modified by substrate concentrations in the same manner as for purified rabbit mammary gland fatty acid synthetase. - 3. The relative amount of radioactivity incorporated from added acetyl-CoA and malonyl-CoA depended...... of long-chain fatty acids was synthesised from carboxylated acetyl-CoA than from added malonyl-CoA. - 5. It is suggested that acetyl-CoA carboxylase may carboxylate acetate bound to fatty acid synthetase....

  4. Influence of the chain length of surfactant in the modification of zeolites and clays. Removal of atrazine from water solutions.

    Science.gov (United States)

    Toledo-Jaldin, Helen Paola; Blanco-Flores, Alien; Sánchez-Mendieta, Víctor; Martín-Hernández, Osnieski

    2017-08-30

    Removal potentials of a surfactant modified zeolite (SMZ) and clay (SMC) for atrazine adsorption were evaluated. Materials were modified with hexadecyl trimethyl ammonium bromide (HDTMA-Br) and benzyl octadecyl dimethyl ammonium (BODA) chloride considering the critical micellar concentration (CMC) of each one (0.94 and 0.041 meq/L, respectively). The influence of the surfactant was analyzed in detail, particularly the formation of surfactant layers (complete or partial) connected with the length of the surfactant tail (16 and 18 methyl groups or number of carbons in the chain). Raw materials were characterized by XRD and Fourier transform infrared spectroscopy (FTIR), SMZ and SMC were analyzed by FTIR. Results obtained from kinetic adsorption experiments shown that equilibrium time is less for materials modified with HDTMA (8 h) than materials with BODA (10 and 12 h). Materials modified with the largest chain surfactant (BODA) showed more resistance to atrazine masse transference. The chemisorption was presented in the adsorption mechanisms of atrazine and adsorbent materials. Based on the results of adsorption isotherms Langmuir isotherms showed the better correlation coefficients value. The q max is greater for materials modified with BODA (0.9232 and 4.2448 mg/g) than for materials modified with HDTMA (0.6731 and 3.9121 mg/g). Therefore, SMZ and SMC modified with the largest chain surfactant has more affinity for the pesticide. The removal process at high concentration of atrazine depends of the partition process but at lower concentration, it occurs not only by this process but also by absorption process.

  5. Effects of hydrophobic helix length and side chain chemistry on biomimicry in peptoid analogues of SP-C.

    Science.gov (United States)

    Brown, Nathan J; Wu, Cindy W; Seurynck-Servoss, Shannon L; Barron, Annelise E

    2008-02-12

    The hydrophobic proteins of lung surfactant (LS), SP-B and SP-C, are critical constituents of an effective surfactant replacement therapy for the treatment of respiratory distress syndrome. Because of concerns and difficulties associated with animal-derived surfactants, recent investigations have focused on the creation of synthetic analogues of the LS proteins. However, creating an accurate mimic of SP-C that retains its biophysical surface activity is extraordinarily challenging given the lipopeptide's extreme hydrophobicity and propensity to misfold and aggregate. One successful approach that overcomes these difficulties is the use of poly-N-substituted glycines, or peptoids, to mimic SP-C. To develop a non-natural, bioactive mimic of SP-C and to investigate the effects of side chain chemistry and length of the helical hydrophobic region, we synthesized, purified, and performed in vitro testing of two classes of peptoid SP-C mimics: those having a rigid alpha-chiral aromatic helix and those having a biomimetic alpha-chiral aliphatic helix. The length of the two classes of mimics was also systematically altered. Circular dichroism spectroscopy gave evidence that all of the peptoid-based mimics studied here emulated SP-C's secondary structure, forming stable helical structures in solution. Langmuir-Wilhelmy surface balance, fluorescence microscopy, and pulsating bubble surfactometry experiments provide evidence that the aromatic-based SP-C peptoid mimics, in conjunction with a synthetic lipid mixture, have superior surface activity and biomimetic film morphology in comparison to the aliphatic-based mimics and that there is an increase in surface activity corresponding to increasing helical length.

  6. Fabrication and tribological properties of self-assembled monolayer of n-alkyltrimethoxysilane on silicon: Effect of SAM alkyl chain length

    Energy Technology Data Exchange (ETDEWEB)

    Huo, Lixia [National Key Laboratory of Science and Technology on Vacuum Technology and Physics, Lanzhou Institute of Physics, Lanzhou, Gansu 730010 (China); Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Lanzhou University, Gansu 730000 (China); Du, Pengcheng [Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Lanzhou University, Gansu 730000 (China); Zhou, Hui; Zhang, Kaifeng [National Key Laboratory of Science and Technology on Vacuum Technology and Physics, Lanzhou Institute of Physics, Lanzhou, Gansu 730010 (China); Liu, Peng, E-mail: pliu@lzu.edu.cn [Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Lanzhou University, Gansu 730000 (China)

    2017-02-28

    Highlights: • n-Alkyltrimethoxysilanes with various chain lengths were self-assembled on silicon. • Effect of alkyl chain lengths (C6, C12, or C18) on the SAMs was investigated. • Surface roughness of the SAMs decreased with increasing the alkyl chain lengths. • The C{sub 12}-SAM possessed superior friction reduction and wear resistance. - Abstract: It is well known that the self-assembled organic molecules on a solid surface exhibit the friction-reducing performance. However, the effect of the molecular size of the self-assembled organic molecules has not been established. In the present work, self-assembled monolayers (SAMs) of n-alkyltrimethoxysilanes with different alkyl chain lengths (C{sub 6}, C{sub 12}, or C{sub 18}) were fabricated on silicon substrate. The water contact angles of the SAMs increased from 26.8° of the hydroxylated silicon substrate to near 60° after self-assembly. The atomic force microscopy (AFM) analysis results showed that the mean roughness (R{sub a}) of the SAMs decreased with increasing the alkyl chain length. The tribological properties of the SAMs sliding against Al{sub 2}O{sub 3} ball were evaluated on an UMT-2 tribometer, and the worn surfaces of the samples were analyzed by means of Nano Scratch Tester and surface profilometry. It was found that lowest friction coefficient and smallest width of wear were achieved with the SAMs of C{sub 12} alkyl chain (C{sub 12}-SAM). The superior friction reduction and wear resistance of the SAMs in comparison with the bare silicon substrate are attributed to good adhesion of the self-assembled films to the substrate, especially the C{sub 12}-SAM with desirable alkyl chain length.

  7. Fabrication and tribological properties of self-assembled monolayer of n-alkyltrimethoxysilane on silicon: Effect of SAM alkyl chain length

    International Nuclear Information System (INIS)

    Huo, Lixia; Du, Pengcheng; Zhou, Hui; Zhang, Kaifeng; Liu, Peng

    2017-01-01

    Highlights: • n-Alkyltrimethoxysilanes with various chain lengths were self-assembled on silicon. • Effect of alkyl chain lengths (C6, C12, or C18) on the SAMs was investigated. • Surface roughness of the SAMs decreased with increasing the alkyl chain lengths. • The C 12 -SAM possessed superior friction reduction and wear resistance. - Abstract: It is well known that the self-assembled organic molecules on a solid surface exhibit the friction-reducing performance. However, the effect of the molecular size of the self-assembled organic molecules has not been established. In the present work, self-assembled monolayers (SAMs) of n-alkyltrimethoxysilanes with different alkyl chain lengths (C 6 , C 12 , or C 18 ) were fabricated on silicon substrate. The water contact angles of the SAMs increased from 26.8° of the hydroxylated silicon substrate to near 60° after self-assembly. The atomic force microscopy (AFM) analysis results showed that the mean roughness (R a ) of the SAMs decreased with increasing the alkyl chain length. The tribological properties of the SAMs sliding against Al 2 O 3 ball were evaluated on an UMT-2 tribometer, and the worn surfaces of the samples were analyzed by means of Nano Scratch Tester and surface profilometry. It was found that lowest friction coefficient and smallest width of wear were achieved with the SAMs of C 12 alkyl chain (C 12 -SAM). The superior friction reduction and wear resistance of the SAMs in comparison with the bare silicon substrate are attributed to good adhesion of the self-assembled films to the substrate, especially the C 12 -SAM with desirable alkyl chain length.

  8. Spacer grid corner gusset

    International Nuclear Information System (INIS)

    Larson, J.G.

    1984-01-01

    There is provided a spacer grid for a bundle of longitudinally extending rods in spaced generally parallel relationship comprising spacing means for holding the rods in spaced generally parallel relationship; the spacing means includes at least one exterior grid strip circumscribing the bundle of rods along the periphery thereof; with at least one exterior grid strip having a first edge defining the boundary of the strip in one longitudinal direction and a second edge defining the boundary of the strip in the other longitudinal direction; with at least one exterior grid strip having at least one band formed therein parallel to the longitudinal direction; a plurality of corner gussets truncating each of a plurality of corners formed by at least one band and the first edge and the second edge

  9. Comparison of Chain-Length Preferences and Glucan Specificities of Isoamylase-Type α-Glucan Debranching Enzymes from Rice, Cyanobacteria, and Bacteria.

    Directory of Open Access Journals (Sweden)

    Taiki Kobayashi

    Full Text Available It has been believed that isoamylase (ISA-type α-glucan debranching enzymes (DBEs play crucial roles not only in α-glucan degradation but also in the biosynthesis by affecting the structure of glucans, although molecular basis on distinct roles of the individual DBEs has not fully understood. In an attempt to relate the roles of DBEs to their chain-length specificities, we analyzed the chain-length distribution of DBE enzymatic reaction products by using purified DBEs from various sources including rice, cyanobacteria, and bacteria. When DBEs were incubated with phytoglycogen, their chain-length specificities were divided into three groups. First, rice endosperm ISA3 (OsISA3 and Eschericia coli GlgX (EcoGlgX almost exclusively debranched chains having degree of polymerization (DP of 3 and 4. Second, OsISA1, Pseudomonas amyloderamosa ISA (PsaISA, and rice pullulanase (OsPUL could debranch a wide range of chains of DP≧3. Third, both cyanobacteria ISAs, Cyanothece ATCC 51142 ISA (CytISA and Synechococcus elongatus PCC7942 ISA (ScoISA, showed the intermediate chain-length preference, because they removed chains of mainly DP3-4 and DP3-6, respectively, while they could also react to chains of DP5-10 and 7-13 to some extent, respectively. In contrast, all these ISAs were reactive to various chains when incubated with amylopectin. In addition to a great variation in chain-length preferences among various ISAs, their activities greatly differed depending on a variety of glucans. Most strikingly, cyannobacteria ISAs could attack branch points of pullulan to a lesser extent although no such activity was found in OsISA1, OsISA3, EcoGlgX, and PsaISA. Thus, the present study shows the high possibility that varied chain-length specificities of ISA-type DBEs among sources and isozymes are responsible for their distinct functions in glucan metabolism.

  10. Bacterial membrane activity of a-peptide/b-peptoid chimeras: Influence of amino acid composition and chain length on the activity against different bacterial strains

    DEFF Research Database (Denmark)

    Hein-Kristensen, Line; Knapp, Kolja M; Franzyk, Henrik

    2011-01-01

    and subsequent killing is usually not tested. In this report, six α-peptide/β-peptoid chimeras were examined for the effect of amino acid/peptoid substitutions and chain length on the membrane perturbation and subsequent killing of food-borne and clinical bacterial isolates. RESULTS: All six AMP analogues...... acid only had a minor effect on MIC values, whereas chain length had a profound influence on activity. All chimeras were less active against Serratia marcescens (MICs above 46 μM). The chimeras were bactericidal and induced leakage of ATP from Staphylococcus aureus and S. marcescens with similar time...... of onset and reduction in the number of viable cells. EDTA pre-treatment of S. marcescens and E. coli followed by treatment with chimeras resulted in pronounced killing indicating that disintegration of the Gram-negative outer membrane eliminated innate differences in susceptibility. Chimera chain length...

  11. On the chain length dependence of local correlations in polymer melts and a perturbation theory of symmetric polymer blends.

    Science.gov (United States)

    Morse, David C; Chung, Jun Kyung

    2009-06-14

    The self-consistent field (SCF) approach to the thermodynamics of dense polymer liquids is based on the idea that short-range correlations in a polymer liquid are almost independent of how monomers are connected into polymers over larger scales. Some limits of this idea are explored in the context of a perturbation theory for symmetric polymer blends. We consider mixtures of two structurally identical polymers, A and B, in which the AB monomer pair interaction differs slightly from the AA and BB interactions by an amount proportional to a parameter alpha. An expansion of the free energy to first order in alpha yields an excess free energy of mixing per monomer of the form alphaz(N)phi(A)phi(B) in both lattice and continuum models, where z(N) is a measure of the number of intermolecular near neighbors per monomer in a one-component (alpha=0) reference liquid with chains of length N. The quantity z(N) decreases slightly with increasing N because the concentration of intramolecular near neighbors is slightly higher for longer chains, creating a slightly deeper intermolecular correlation hole. We predict that z(N)=z(infinity)[1+betaN(-1/2)], where N is an invariant degree of polymerization and beta=(6/pi)(3/2) is a universal coefficient. This and related predictions about the slight N dependence of local correlations are confirmed by comparison to simulations of a continuum bead-spring model and to published lattice Monte Carlo simulations. We show that a renormalized one-loop theory for blends correctly describes this N dependence of local liquid structure. We also propose a way to estimate the effective interaction parameter appropriate for comparisons of simulation data to SCF theory and to coarse-grained theories of corrections to SCF theory, which is based on an extrapolation of perturbation theory to the limit N-->infinity.

  12. Interaction and dynamics of (alkylamide + electrolyte) deep eutectics: Dependence on alkyl chain-length, temperature, and anion identity

    Energy Technology Data Exchange (ETDEWEB)

    Guchhait, Biswajit; Das, Suman; Daschakraborty, Snehasis; Biswas, Ranjit, E-mail: ranjit@bose.res.in [Department of Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098 (India)

    2014-03-14

    Here we investigate the solute-medium interaction and solute-centered dynamics in (RCONH{sub 2} + LiX) deep eutectics (DEs) via carrying out time-resolved fluorescence measurements and all-atom molecular dynamics simulations at various temperatures. Alkylamides (RCONH{sub 2}) considered are acetamide (CH{sub 3}CONH{sub 2}), propionamide (CH{sub 3}CH{sub 2}CONH{sub 2}), and butyramide (CH{sub 3}CH{sub 2}CH{sub 2}CONH{sub 2}); the electrolytes (LiX) are lithium perchlorate (LiClO{sub 4}), lithium bromide (LiBr), and lithium nitrate (LiNO{sub 3}). Differential scanning calorimetric measurements reveal glass transition temperatures (T{sub g}) of these DEs are ∼195 K and show a very weak dependence on alkyl chain-length and electrolyte identity. Time-resolved and steady state fluorescence measurements with these DEs have been carried out at six-to-nine different temperatures that are ∼100–150 K above their individual T{sub g}s. Four different solute probes providing a good spread of fluorescence lifetimes have been employed in steady state measurements, revealing strong excitation wavelength dependence of probe fluorescence emission peak frequencies. Extent of this dependence, which shows sensitivity to anion identity, has been found to increase with increase of amide chain-length and decrease of probe lifetime. Time-resolved measurements reveal strong fractional power dependence of average rates for solute solvation and rotation with fraction power being relatively smaller (stronger viscosity decoupling) for DEs containing longer amide and larger (weaker decoupling) for DEs containing perchlorate anion. Representative all-atom molecular dynamics simulations of (CH{sub 3}CONH{sub 2} + LiX) DEs at different temperatures reveal strongly stretched exponential relaxation of wavevector dependent acetamide self dynamic structure factor with time constants dependent both on ion identity and temperature, providing justification for explaining the fluorescence results in

  13. Surface-Tethered Iterative Carbohydrate Synthesis (STICS): A spacer study

    Science.gov (United States)

    Ganesh, N. Vijaya; Fujikawa, Kohki; Tan, Yih Horng; Nigudkar, Swati S.

    2013-01-01

    Comparative study of STICS using HPLC-assisted experimental set-up clearly demonstrated benefits of using longer spacer-anchoring systems. The use of mixed self-assembled monolayers helps to provide the required space for glycosylation reaction around the immobilized glycosyl acceptor. Both extension of the spacer length and using mixed self-assembled monolayers help to promote reaction and the beneficial effects may include moving the glycosyl acceptor further out into solution and providing additional conformational flexibility. It is possible that surface-immobilized glycosyl acceptors with a longer spacer (C8-O-C8)-lipoic acid have a higher tendency to mimic a solution-phase reaction environment than that of acceptors with shorter spacers. PMID:23822088

  14. Influence of trehalose 6,6'-diester (TDX) chain length on the physicochemical and immunopotentiating properties of DDA/TDX liposomes

    DEFF Research Database (Denmark)

    Kallerup, Rie Selchau; Madsen, Cecilie Maria; Schiøth, Mikkel Lohmann

    2015-01-01

    Linking physicochemical characterization to functional properties is crucial for defining critical quality attributes during development of subunit vaccines toward optimal safety and efficacy profiles. We investigated how the trehalose 6,6'-diester (TDX) chain length influenced the physicochemical...... and immunopotentiating properties of the clinically tested liposomal adjuvant composed of dimethyldioctadecylammonium (DDA) bromide and analogues of trehalose-6,6'-dibehenate (TDB). TDB analogues with symmetrically shortened acyl chains [denoted X: arachidate (A), stearate (S), palmitate (P), myristate (Myr) and laurate...

  15. Photoluminescence and self-assembly of cesium lead halide perovskite nanocrystals: Effects of chain length of organic amines and reaction temperature

    International Nuclear Information System (INIS)

    Yuan, Yi; Liu, Zheming; Liu, Zhenyang; Peng, Lan; Li, Yongjie; Tang, Aiwei

    2017-01-01

    Highlights: • CsPbBr_3 perovskite nanocrystals have been synthesized in the presence of organic amines with different hydrocarbon length. • The photoluminescence of the CsPbBr_3 nanocrystals is affected by the varying the carbon length of the organic amines. • The lower reaction temperature and hydrocarbon chain length of the organic ligands play a significant role in the self-assembly of CsPbBr_3 nanocrystals. - Abstract: All-inorganic halide perovskites have become one of the most prospective materials for lightening and display technology due to their color-tunable and narrow-band emission. Herein, we have systematically studied the effects of organic amines with different hydrocarbon chain length on the optical properties and morphology as well as the crystal structure of colloidal CsPbBr_3 nanocrystals (NCs), which were synthesized in the presence of oleic acid (OA) and organic amines by using a simple hot-injection approach. The hydrocarbon chain length has shown an independent correlation to the morphology and crystal structure of the as-obtained CsPbBr_3 NCs at 160 °C, but their optical properties can be affected to some extent. The photoluminescence quantum yields (PLQYs) of the CsPbBr_3 NCs synthesized in the presence of organic amines with long carbon chain length are generally in the range of 55–80% for different reaction time, but the PLQYs of less than 20% are obtained for the products synthesized in the presence of octylamine (OTAm) with short carbon chain length. The effects of the reaction temperature on the optical properties, size and crystal structure of the CsPbBr_3 NCs synthesized in the presence of cetylamine (CTAm) are studied. Interestingly, some nanoplates also appear in these CsPbBr_3 NCs obtained at relatively low temperatures (120 and 140 °C), which have a strong tendency to self-assemble into face-to-face nanostructures. Such a similar self-assembly behavior is also observed in the product synthesized in the presence of

  16. Photoluminescence and self-assembly of cesium lead halide perovskite nanocrystals: Effects of chain length of organic amines and reaction temperature

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Yi; Liu, Zheming; Liu, Zhenyang; Peng, Lan; Li, Yongjie; Tang, Aiwei, E-mail: awtang@bjtu.edu.cn

    2017-05-31

    Highlights: • CsPbBr{sub 3} perovskite nanocrystals have been synthesized in the presence of organic amines with different hydrocarbon length. • The photoluminescence of the CsPbBr{sub 3} nanocrystals is affected by the varying the carbon length of the organic amines. • The lower reaction temperature and hydrocarbon chain length of the organic ligands play a significant role in the self-assembly of CsPbBr{sub 3} nanocrystals. - Abstract: All-inorganic halide perovskites have become one of the most prospective materials for lightening and display technology due to their color-tunable and narrow-band emission. Herein, we have systematically studied the effects of organic amines with different hydrocarbon chain length on the optical properties and morphology as well as the crystal structure of colloidal CsPbBr{sub 3} nanocrystals (NCs), which were synthesized in the presence of oleic acid (OA) and organic amines by using a simple hot-injection approach. The hydrocarbon chain length has shown an independent correlation to the morphology and crystal structure of the as-obtained CsPbBr{sub 3} NCs at 160 °C, but their optical properties can be affected to some extent. The photoluminescence quantum yields (PLQYs) of the CsPbBr{sub 3} NCs synthesized in the presence of organic amines with long carbon chain length are generally in the range of 55–80% for different reaction time, but the PLQYs of less than 20% are obtained for the products synthesized in the presence of octylamine (OTAm) with short carbon chain length. The effects of the reaction temperature on the optical properties, size and crystal structure of the CsPbBr{sub 3} NCs synthesized in the presence of cetylamine (CTAm) are studied. Interestingly, some nanoplates also appear in these CsPbBr{sub 3} NCs obtained at relatively low temperatures (120 and 140 °C), which have a strong tendency to self-assemble into face-to-face nanostructures. Such a similar self-assembly behavior is also observed in the

  17. Evaluation of medium-chain-length polyhydroxyalkanoate production by Pseudomonas putida LS46 using biodiesel by-product streams.

    Science.gov (United States)

    Fu, Jilagamazhi; Sharma, Umesh; Sparling, Richard; Cicek, Nazim; Levin, David B

    2014-07-01

    Medium-chain-length polyhydroxyalkanoate (mcl-PHA) production by Pseudomonas putida LS46 was analyzed in shake-flask-based batch reactions, using pure chemical-grade glycerol (PG), biodiesel-derived "waste" glycerol (WG), and biodiesel-derived "waste" free fatty acids (WFA). Cell growth, substrate consumption, mcl-PHA accumulation within the cells, and the monomer composition of the synthesized biopolymers were monitored. The patterns of mcl-PHA synthesis in P. putida LS46 cells grown on PG and WG were similar but differed from that of cells grown with WFA. Polymer accumulation in glycerol-based cultures was stimulated by nitrogen limitation and plateaued after 48 h in both PG and WG cultures, with a total accumulation of 17.9% cell dry mass and 16.3% cell dry mass, respectively. In contrast, mcl-PHA synthesis was independent of nitrogen concentration in P. putida LS46 cells cultured with WFA, which accumulated to 29% cell dry mass. In all cases, the mcl-PHAs synthesized consisted primarily of 3-hydroxyoctanoate (C(8)) and 3-hydroxydecanoate (C(10)). WG and WFA supported similar or greater cell growth and mcl-PHA accumulation than PG under the experimental conditions used. These results suggest that biodiesel by-product streams could be used as low-cost carbon sources for sustainable mcl-PHA production.

  18. Identification of Echinococcus granulosus strains using polymerase chain reaction-restriction fragment length polymorphism amongst livestock in Moroto district, Uganda.

    Science.gov (United States)

    Chamai, Martin; Omadang, Leonard; Erume, Joseph; Ocaido, Michael; Oba, Peter; Othieno, Emmanuel; Bonaventure, Straton; Kitibwa, Annah

    2016-07-29

    A descriptive study was conducted to identify the different strains of Echinococcus granulosus occurring in livestock in Moroto district, Uganda. Echinococcus cysts from 104 domestic animals, including cattle, sheep, goats and camels, were taken and examined by microscopy, polymerase chain reaction with restriction fragment length polymorphism and Sanger DNA sequencing. Echinococcus granulosus genotypes or strains were identified through use of Bioinformatics tools: BioEdit, BLAST and MEGA6. The major finding of this study was the existence of a limited number of E. granulosus genotypes from cattle, goats, sheep and camels. The most predominant genotype was G1 (96.05%), corresponding to the common sheep strain. To a limited extent (3.95%), the study revealed the existence of Echinococcus canadensis G6/7 in three (n = 3) of the E. granulosus-positive samples. No other strains of E. granulosus were identified. It was concluded that the common sheep strain of Echinococcus sensu stricto and G6/7 of E. canadensis were responsible for echinococcal disease in Moroto district, Uganda.

  19. Effects of Odd–Even Side Chain Length of Alkyl-Substituted Diphenylbithiophenes on First Monolayer Thin Film Packing Structure

    KAUST Repository

    Akkerman, Hylke B.

    2013-07-31

    Because of their preferential two-dimensional layer-by-layer growth in thin films, 5,5′bis(4-alkylphenyl)-2,2′-bithiophenes (P2TPs) are model compounds for studying the effects of systematic chemical structure variations on thin-film structure and morphology, which in turn, impact the charge transport in organic field-effect transistors. For the first time, we observed, by grazing incidence X-ray diffraction (GIXD), a strong change in molecular tilt angle in a monolayer of P2TP, depending on whether the alkyl chain on the P2TP molecules was of odd or even length. The monolayers were deposited on densely packed ultrasmooth self-assembled alkane silane modified SiO2 surfaces. Our work shows that a subtle change in molecular structure can have a significant impact on the molecular packing structure in thin film, which in turn, will have a strong impact on charge transport of organic semiconductors. This was verified by quantum-chemical calculations that predict a corresponding odd-even effect in the strength of the intermolecular electronic coupling. © 2013 American Chemical Society.

  20. Medium-chain-length poly-3-hydroxyalkanoates-carbon nanotubes composite anode enhances the performance of microbial fuel cell.

    Science.gov (United States)

    Hindatu, Y; Annuar, M S M; Subramaniam, R; Gumel, A M

    2017-06-01

    Insufficient power generation from a microbial fuel cell (MFC) hampers its progress towards utility-scale development. Electrode modification with biopolymeric materials could potentially address this issue. In this study, medium-chain-length poly-3-hydroxyalkanoates (PHA)/carbon nanotubes (C) composite (CPHA) was successfully applied to modify the surface of carbon cloth (CC) anode in MFC. Characterization of the functional groups on the anodic surface and its morphology was carried out. The CC-CPHA composite anode recorded maximum power density of 254 mW/m 2 , which was 15-53% higher than the MFC operated with CC-C (214 mW/m 2 ) and pristine CC (119 mW/m 2 ) as the anode in a double-chambered MFC operated with Escherichia coli as the biocatalyst. Electrochemical impedance spectroscopy and cyclic voltammetry showed that power enhancement was attributed to better electron transfer capability by the bacteria for the MFC setup with CC-CPHA anode.

  1. The Impact of Polyether Chain Length on the Iron Clearing Efficiency and Physiochemical Properties of Desferrithiocin Analogues

    Science.gov (United States)

    Bergeron, Raymond J.; Bharti, Neelam; Wiegand, Jan; McManis, James S.; Singh, Shailendra; Abboud, Khalil A.

    2010-01-01

    (S)-2-(2,4-Dihydroxyphenyl)-4,5-dihydro-4-methyl-4-thiazolecarboxylic acid (2) was abandoned in clinical trials as an iron chelator for the treatment of iron overload disease because of its nephrotoxicity. However, subsequent investigations revealed that replacing the 4′-(HO) of 2 with a 3,6,9-trioxadecyloxy group, ligand 4, increased iron clearing efficiency (ICEa) and ameliorated the renal toxicity of 2. This compelled a closer look at additional polyether analogues, the subject of this work. The 3,6,9,12-tetraoxatridecyloxy analogue of 4, chelator 5, an oil, had twice the ICE in rodents of 4, although its ICE in primates was reduced relative to 4. The corresponding 3,6-dioxaheptyloxy analogue of 2, 6 (a crystalline solid), had high ICEs in both the rodent and primate models. It significantly decorporated hepatic, renal, and cardiac iron, with no obvious histopathologies. These findings suggest that polyether chain length has a profound effect on ICE, tissue iron decorporation, and ligand physiochemical properties. PMID:20232803

  2. Limits of a rapid identification of common Mediterranean sandflies using polymerase chain reaction-restriction fragment length polymorphism

    Directory of Open Access Journals (Sweden)

    Azzedine Bounamous

    2014-07-01

    Full Text Available A total of 131 phlebotomine Algerian sandflies have been processed in the present study. They belong to the species Phlebotomus bergeroti, Phlebotomus alexandri, Phlebotomus sergenti, Phlebotomus chabaudi, Phlebotomus riouxi, Phlebotomus perniciosus, Phlebotomus longicuspis, Phlebotomus perfiliewi, Phlebotomus ariasi, Phlebotomus chadlii, Sergentomyia fallax, Sergentomyia minuta, Sergentomyia antennata, Sergentomyia schwetzi, Sergentomyia clydei, Sergentomyia christophersi and Grassomyia dreyfussi. They have been characterised by sequencing of a part of the cytochrome b (cyt b, t RNA serine and NADH1 on the one hand and of the cytochrome C oxidase I of the mitochondrial DNA (mtDNA on the other hand. Our study highlights two sympatric populations within P. sergenti in the area of its type-locality and new haplotypes of P. perniciosus and P. longicuspis without recording the specimens called lcx previously found in North Africa. We tried to use a polymerase chain reaction-restriction fragment length polymorphism method based on a combined double digestion of each marker. These method is not interesting to identify sandflies all over the Mediterranean Basin.

  3. Effects of Odd–Even Side Chain Length of Alkyl-Substituted Diphenylbithiophenes on First Monolayer Thin Film Packing Structure

    KAUST Repository

    Akkerman, Hylke B.; Mannsfeld, Stefan C. B.; Kaushik, Ananth P.; Verploegen, Eric; Burnier, Luc; Zoombelt, Arjan P.; Saathoff, Jonathan D.; Hong, Sanghyun; Atahan-Evrenk, Sule; Liu, Xueliang; Aspuru-Guzik, Alá n; Toney, Michael F.; Clancy, Paulette; Bao, Zhenan

    2013-01-01

    Because of their preferential two-dimensional layer-by-layer growth in thin films, 5,5′bis(4-alkylphenyl)-2,2′-bithiophenes (P2TPs) are model compounds for studying the effects of systematic chemical structure variations on thin-film structure and morphology, which in turn, impact the charge transport in organic field-effect transistors. For the first time, we observed, by grazing incidence X-ray diffraction (GIXD), a strong change in molecular tilt angle in a monolayer of P2TP, depending on whether the alkyl chain on the P2TP molecules was of odd or even length. The monolayers were deposited on densely packed ultrasmooth self-assembled alkane silane modified SiO2 surfaces. Our work shows that a subtle change in molecular structure can have a significant impact on the molecular packing structure in thin film, which in turn, will have a strong impact on charge transport of organic semiconductors. This was verified by quantum-chemical calculations that predict a corresponding odd-even effect in the strength of the intermolecular electronic coupling. © 2013 American Chemical Society.

  4. Haplotyping the human T-cell receptor β-chain gene complex by use of restriction fragment length polymorphisms

    International Nuclear Information System (INIS)

    Charmley, P.; Chao, A.; Gatti, R.A.; Concannon, P.; Hood, L.

    1990-01-01

    The authors have studied the genetic segregation of human T-cell receptor β-chain (TCRβ) genes on chromosome 7q in 40 CEPH (Centre d'Etude du Polymorphisme Humain) families by using restriction fragment length polymorphisms (RFLPs). They constructed haplotypes from eight RFLPs by using variable- and constant-region cDNA probes, which detect polymorphisms that span more than 600 kilobases of the TCRβ gene complex. Analysis of allele distributions between TCRβ genes revealed significant linkage disequilibrium between only 6 of the 28 different pairs of RFLPs. This linkage disequilibrium strongly influences the most efficient order to proceed for typing of these RFLPs in order to achieve maximum genetic informativeness, which in this study revealed a 97.3% level of heterozygosity within the TCRβ gene complex. The results should provide new insight into recent reports of disease associations with the TCRβ gene complex and should assist in designing future experiments to detect or confirm the existence of disease-susceptibility loci in this region of the human genome

  5. Rapid differentiation of closely related isolates of two plant viruses by polymerase chain reaction and restriction fragment length polymorphism analysis.

    Science.gov (United States)

    Barbara, D J; Morton, A; Spence, N J; Miller, A

    1995-09-01

    Immunocapture reverse transcriptase-polymerase chain reaction (RT-PCR) followed by restriction fragment length polymorphism (RFLP) analysis of the product has been shown to be an effective procedure for discriminating serologically indistinguishable isolates of two plant viruses, raspberry bushy dwarf (RBDV) and zucchini yellow mosaic (ZYMV). For both viruses, only limited sequence information was available at the time of primer design, but most of the isolates which were tested could be amplified (the one exception being a serologically quite distinct isolate of ZYMV). Restriction endonucleases revealing diagnostic RFLPs were readily identified. Each of two isolates of ZYMV could be detected in the presence of the other and the relative proportions approximately quantified by visual estimation of the relative intensity of the appropriate bands. A range of isolates of different RBDV pathotypes were compared; isolates were grouped in ways that accorded with their known history. Computer analysis of the published sequence from which the primers had been derived showed the sequenced isolate to be identical with an isolate imported from the USSR. The PCR/RFLP procedure is rapid (it can be completed in less than 2 days), effective and will probably be generally applicable to distinguishing closely related virus isolates, even where little sequence information is available.

  6. Lyme disease with facial nerve palsy: rapid diagnosis using a nested polymerase chain reaction-restriction fragment length polymorphism analysis.

    Science.gov (United States)

    Hashimoto, Y; Takahashi, H; Kishiyama, K; Sato, Y; Nakao, M; Miyamoto, K; Iizuka, H

    1998-02-01

    A 64-year-old woman with Lyme disease and manifesting facial nerve palsy had been bitten by a tick on the left frontal scalp 4 weeks previously. Erythema migrans appeared on the left forehead, accompanied by left facial paralysis. Nested polymerase chain reaction-restriction fragment length polymorphism analysis (nested PCR-RFLP) was performed on DNA extracted from a skin biopsy of the erythema on the left forehead. Borrelia flagellin gene DNA was detected and its RFLP pattern indicated that the organism was B. garinii, Five weeks later, B. garinii was isolated by conventional culture from the erythematous skin lesion, but not from the cerebrospinal fluid. After treatment with ceftriaxone intravenously for 10 days and oral administration of minocycline for 7 days, both the erythema and facial nerve palsy improved significantly. Nested PCR and culture taken after the lesion subsided, using skin samples obtained from a site adjacent to the original biopsy, were both negative. We suggest that nested PCR-RFLP analysis might be useful for the rapid diagnosis of Lyme disease and for evaluating therapy.

  7. An Assessment of Weight-Length Relationships for Muskellunge,Northern Pike, and Chain Pickerel In Carlander's Handbook of Freshwater Fishery Biology

    OpenAIRE

    Daviscourt, Joshua; Huertas, Joshua; Courtney, Michael

    2011-01-01

    Carlander's Handbook of Freshwater Fishery Biology (1969) contains life history data from many species of freshwater fish found in North America. It has been cited over 1200 times and used to produce standard-weight curves for some species. Recent work (Cole-Fletcher et al. 2011) suggests Carlander (1969) contains numerous errors in listed weight-length equations. This paper assesses the weight-length relationships listed in Carlander for muskellunge, northern pike, and chain pickerel by comp...

  8. Inhibition of nuclear T3 binding by fatty acids: dependence on chain length, unsaturated bonds, cis-trans configuration and esterification

    NARCIS (Netherlands)

    Wiersinga, W. M.; Platvoet-ter Schiphorst, M.

    1990-01-01

    1. Fatty acids have the capacity for inhibition of nuclear T3 binding (INB). The present studies were undertaken to describe the INB-activity of fatty acids as a function of chain length, unsaturated bonds, cis-trans configuration, and esterification. 2. Isolated rat liver nuclei were incubated with

  9. Characterisation of Toxoplasma gondii isolates using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) of the non-coding Toxoplasma gondii (TGR)-gene sequences

    DEFF Research Database (Denmark)

    Høgdall, Estrid; Vuust, Jens; Lind, Peter

    2000-01-01

    of using TGR gene variants as markers to distinguish among T. gondii isolates from different animals and different geographical sources. Based on the band patterns obtained by restriction fragment length polymorphism (RFLP) analysis of the polymerase chain reaction (PCR) amplified TGR sequences, the T...

  10. Ribosomal DNA internal transcribed spacer 1 and internal ...

    African Journals Online (AJOL)

    USER

    2010-07-26

    Jul 26, 2010 ... in some East Asian countries such as China, Korea and. *Corresponding author. E-mail: soonkwan@kangwon.ac.kr. Tel: +82 33 250 6476. Fax: +82 33 250 6470. Abbreviations: nrDNA, Nuclear ribosomal DNA; ITS, internal transcribed spacer; PCR, polymerase chain reaction; BLAST, basic local alignment ...

  11. Lid opening and conformational stability of T1 Lipase is mediated by increasing chain length polar solvents

    Directory of Open Access Journals (Sweden)

    Jonathan Maiangwa

    2017-05-01

    Full Text Available The dynamics and conformational landscape of proteins in organic solvents are events of potential interest in nonaqueous process catalysis. Conformational changes, folding transitions, and stability often correspond to structural rearrangements that alter contacts between solvent molecules and amino acid residues. However, in nonaqueous enzymology, organic solvents limit stability and further application of proteins. In the present study, molecular dynamics (MD of a thermostable Geobacillus zalihae T1 lipase was performed in different chain length polar organic solvents (methanol, ethanol, propanol, butanol, and pentanol and water mixture systems to a concentration of 50%. On the basis of the MD results, the structural deviations of the backbone atoms elucidated the dynamic effects of water/organic solvent mixtures on the equilibrium state of the protein simulations in decreasing solvent polarity. The results show that the solvent mixture gives rise to deviations in enzyme structure from the native one simulated in water. The drop in the flexibility in H2O, MtOH, EtOH and PrOH simulation mixtures shows that greater motions of residues were influenced in BtOH and PtOH simulation mixtures. Comparing the root mean square fluctuations value with the accessible solvent area (SASA for every residue showed an almost correspondingly high SASA value of residues to high flexibility and low SASA value to low flexibility. The study further revealed that the organic solvents influenced the formation of more hydrogen bonds in MtOH, EtOH and PrOH and thus, it is assumed that increased intraprotein hydrogen bonding is ultimately correlated to the stability of the protein. However, the solvent accessibility analysis showed that in all solvent systems, hydrophobic residues were exposed and polar residues tended to be buried away from the solvent. Distance variation of the tetrahedral intermediate packing of the active pocket was not conserved in organic solvent

  12. 4-N-, 4-S-, and 4-O-chloroquine analogues: influence of side chain length and quinolyl nitrogen pKa on activity vs chloroquine resistant malaria.

    Science.gov (United States)

    Natarajan, Jayakumar K; Alumasa, John N; Yearick, Kimberly; Ekoue-Kovi, Kekeli A; Casabianca, Leah B; de Dios, Angel C; Wolf, Christian; Roepe, Paul D

    2008-06-26

    Using predictions from heme-quinoline antimalarial complex structures, previous modifications of chloroquine (CQ), and hypotheses for chloroquine resistance (CQR), we synthesize and assay CQ analogues that test structure-function principles. We vary side chain length for both monoethyl and diethyl 4-N CQ derivatives. We alter the pKa of the quinolyl N by introducing alkylthio or alkoxy substituents into the 4 position and vary side chain length for these analogues. We introduce an additional titratable amino group to the side chain of 4-O analogues with promising CQR strain selectivity and increase activity while retaining selectivity. We solve atomic resolution structures for complexes formed between representative 4-N, 4-S, and 4-O derivatives vs mu-oxo dimeric heme, measure binding constants for monomeric vs dimeric heme, and quantify hemozoin (Hz) formation inhibition in vitro. The data provide additional insight for the design of CQ analogues with improved activity vs CQR malaria.

  13. 4-N, 4-S & 4-O Chloroquine Analogues: Influence of Side Chain Length and Quinolyl Nitrogen pKa on Activity vs. Chloroquine Resistant Malaria+, #

    Science.gov (United States)

    Natarajan, Jayakumar K.; Alumasa, John; Yearick, Kimberly; Ekoue-Kovi, Kekeli A.; Casabianca, Leah B.; de Dios, Angel C.; Wolf, Christian; Roepe, Paul D.

    2009-01-01

    Using predictions from heme – quinoline antimalarial complex structures, previous modifications of chloroquine (CQ), and hypotheses for chloroquine resistance (CQR), we synthesize and assay CQ analogues that test structure – function principles. We vary side chain length for both monoethyl and diethyl 4N CQ derivatives. We alter the pKa of the quinolyl N by introducing alkylthio or alkoxy substituents into the 4 position, and vary side chain length for these analogues. We introduce an additional titratable amino group to the side chain of 4O analogues with promising CQR strain selectivity and increase activity while retaining selectivity. We solve atomic resolution structures for complexes formed between representative 4N, 4S and 4O derivatives vs. μ-oxo dimeric heme, measure binding constants for monomeric vs. dimeric heme, and quantify hemozoin (Hz) formation inhibition in vitro. The data provide additional insight for the design of CQ analogues with improved activity vs. CQR malaria. PMID:18512900

  14. (ISSR) and internal transcribed spacer

    African Journals Online (AJOL)

    Cladistic relationships within the genus Cinnamomum (Lauraceae) in Taiwan based on analysis of leaf morphology and inter-simple sequence repeat (ISSR) and internal transcribed spacer (ITS) molecular markers.

  15. Modulation of saturation and chain length of fatty acids in Saccharomyces cerevisiae for production of cocoa butter-like lipids.

    Science.gov (United States)

    Bergenholm, David; Gossing, Michael; Wei, Yongjun; Siewers, Verena; Nielsen, Jens

    2018-04-01

    Chain length and degree of saturation plays an important role for the characteristics of various products derived from fatty acids, such as fuels, cosmetics, and food additives. The seeds of Theobroma cacao are the source of cocoa butter, a natural lipid of high interest for the food and cosmetics industry. Cocoa butter is rich in saturated fatty acids that are stored in the form of triacylglycerides (TAGs). One of the major TAG species of cocoa butter, consisting of two stearic acid molecules and one oleic acid molecule (stearic acid-oleic acid-stearic acid, sn-SOS), is particularly rare in nature as the saturated fatty acid stearic acid is typically found only in low abundance. Demand for cocoa butter is increasing, yet T. cacao can only be cultivated in some parts of the tropics. Alternative means of production of cocoa butter lipids (CBLs) are, therefore, sought after. Yeasts also store fatty acids in the form of TAGs, but these are typically not rich in saturated fatty acids. To make yeast an attractive host for microbial production of CBLs, its fatty acid composition needs to be optimized. We engineered Saccharomyces cerevisiae yeast strains toward a modified fatty acid synthesis. Analysis of the fatty acid profile of the modified strains showed that the fatty acid content as well as the titers of saturated fatty acids and the titers of TAGs were increased. The relative content of potential CBLs in the TAG pool reached up to 22% in our engineered strains, which is a 5.8-fold increase over the wild-type. SOS content reached a level of 9.8% in our engineered strains, which is a 48-fold increase over the wild type. © 2018 Wiley Periodicals, Inc.

  16. The conversion of BTEX compounds by single and defined mixed cultures to medium-chain-length polyhydroxyalkanoate.

    Science.gov (United States)

    Nikodinovic, Jasmina; Kenny, Shane T; Babu, Ramesh P; Woods, Trevor; Blau, Werner J; O'Connor, Kevin E

    2008-09-01

    Here, we report the use of petrochemical aromatic hydrocarbons as a feedstock for the biotechnological conversion into valuable biodegradable plastic polymers--polyhydroxyalkanoates (PHAs). We assessed the ability of the known Pseudomonas putida species that are able to utilize benzene, toluene, ethylbenzene, p-xylene (BTEX) compounds as a sole carbon and energy source for their ability to produce PHA from the single substrates. P. putida F1 is able to accumulate medium-chain-length (mcl) PHA when supplied with toluene, benzene, or ethylbenzene. P. putida mt-2 accumulates mcl-PHA when supplied with toluene or p-xylene. The highest level of PHA accumulated by cultures in shake flask was 26% cell dry weight for P. putida mt-2 supplied with p-xylene. A synthetic mixture of benzene, toluene, ethylbenzene, p-xylene, and styrene (BTEXS) which mimics the aromatic fraction of mixed plastic pyrolysis oil was supplied to a defined mixed culture of P. putida F1, mt-2, and CA-3 in the shake flasks and fermentation experiments. PHA was accumulated to 24% and to 36% of the cell dry weight of the shake flask and fermentation grown cultures respectively. In addition a three-fold higher cell density was achieved with the mixed culture grown in the bioreactor compared to shake flask experiments. A run in the 5-l fermentor resulted in the utilization of 59.6 g (67.5 ml) of the BTEXS mixture and the production of 6 g of mcl-PHA. The monomer composition of PHA accumulated by the mixed culture was the same as that accumulated by single strains supplied with single substrates with 3-hydroxydecanoic acid occurring as the predominant monomer. The purified polymer was partially crystalline with an average molecular weight of 86.9 kDa. It has a thermal degradation temperature of 350 degrees C and a glass transition temperature of -48.5 degrees C.

  17. Manipulating the morphology and textural property of γ-AlOOH by modulating the alkyl chain length of cation in ionic liquid

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Zhe, E-mail: tangzhe1983@163.com; Hu, Xiaofu, E-mail: hjj19850922@126.cn; Liang, Jilei, E-mail: liang.jilei_ttplan@126.com; Zhao, Jinchong, E-mail: Dr.zhaojc@gmail.com; Liu, Yunqi, E-mail: liuyq@upc.edu.cn; Liu, Chenguang, E-mail: cgliu@upc.edu.cn

    2013-06-01

    Graphical abstract: - Highlights: • γ-AlOOH was the only product in all experiments. • Different morphology of γ-AlOOH was obtained according to the alkyl chain length. • The textural property of γ-AlOOH was changed according to the alkyl chain length. • The possible formation mechanisms for hollow sphere and microflower were proposed. - Abstract: We demonstrated that the morphology and textural property of γ-AlOOH can be tuned by modulating the alkyl chain length of cation in [C{sub n}mim]{sup +}Cl{sup −} (n = 4, 8, 16). Using the short alkyl chain length-based [C{sub 4}mim]{sup +}Cl{sup −} as the structure-directed reagent, the morphology of γ-AlOOH was not changed and preserved as the hollow sphere structure in all experiments. The specific area and the number of small meso-pores of γ-AlOOH increased with the increase of [C{sub 4}mim]{sup +}Cl{sup −} dosage. While, using the larger alkyl chain length-based ionic liquids as the soft-template, such as [C{sub 8}mim]{sup +}Cl{sup −} and [C{sub 16}mim]{sup +}Cl{sup −}, the morphologies of γ-AlOOH were changed from initiative hollow spheres into the final microflowers. The specific areas of γ-AlOOH firstly increased then decreased with the increase of their dosage. The samples were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscope (SEM) and Transmission Electron Microscopy (TEM). Furthermore, the possible formation mechanisms of γ-AlOOH have been proposed.

  18. Overexpression of O-polysaccharide chain length regulators in Gram-negative bacteria using the Wzx-/Wzy-dependent pathway enhances production of defined modal length O-polysaccharide polymers for use as haptens in glycoconjugate vaccines.

    Science.gov (United States)

    Hegerle, N; Bose, J; Ramachandran, G; Galen, J E; Levine, M M; Simon, R; Tennant, S M

    2018-03-30

    O-polysaccharide (OPS) molecules are protective antigens for several bacterial pathogens, and have broad utility as components of glycoconjugate vaccines. Variability in the OPS chain length is one obstacle towards further development of these vaccines. Introduction of sizing steps during purification of OPS molecules of suboptimal or of mixed lengths introduces additional costs and complexity while decreasing the final yield. The overall goal of this study was to demonstrate the utility of engineering Gram-negative bacteria to produce homogenous O-polysaccharide populations that can be used as the basis of carbohydrate vaccines by overexpressing O-polysaccharide chain length regulators of the Wzx-/Wzy-dependent pathway. The O-polysaccharide chain length regulators wzzB and fepE from Salmonella Typhimurium I77 and wzz2 from Pseudomonas aeruginosa PAO1 were cloned and expressed in the homologous organism or in other Gram-negative bacteria. Overexpression of these Wzz proteins in the homologous organism significantly increased the proportion of long or very long chain O-polysaccharides. The same observation was made when wzzB was overexpressed in Salmonella Paratyphi A and Shigella flexneri, and wzz2 was overexpressed in two other strains of P. aeruginosa. Overexpression of Wzz proteins in Gram-negative bacteria using the Wzx/Wzy-dependant pathway for lipopolysaccharide synthesis provides a genetic method to increase the production of an O-polysaccharide population of a defined size. The methods presented herein represent a cost-effective and improved strategy for isolating preferred OPS vaccine haptens, and could facilitate the further use of O-polysaccharides in glycoconjugate vaccine development. © 2018 The Society for Applied Microbiology.

  19. Spacer device for nuclear reactor fuel elements

    International Nuclear Information System (INIS)

    Anthony, A.J.; Gaines, A.L.; Krawiec, D.M.

    1974-01-01

    The grid-type spacer device consists of two rows of main spacers arranged parallel to each other with some space in between, the first row extending perpendicular to the second row. Parallel to the respective rows of main spacers there are rows of secondary spacers interlocked with the main spacers. The individual spacers are welded together at their points of intersection. A large number of spring cages are installed within the spacer device to hold in place the main spacers which are oriented at right angles relative to each other. In addition, the spring cages serve for supporting the fuel elements. The spacers are made of zirconium which does not greatly influence the neutron capture cross section of the reactor. The material of the spring cages with the spring elements is a nickel alloy. It has the necessary stress relaxation properties to be able to force the fuel elements against the spacers under the action of the spring. (DG) [de

  20. Effect of surfactant alkyl chain length on the dispersion, and thermal and dynamic mechanical properties of LDPE/organo-LDH composites

    Directory of Open Access Journals (Sweden)

    2011-05-01

    Full Text Available Low density polyethylene/layered double hydroxide (LDH composites were prepared via melt compounding using different kinds of organo-LDHs and polyethylene-grafted maleic anhydride as the compatibilizer. The organo-LDHs were successfully prepared by converting a commercial MgAl-carbonate LDH into a MgAl-nitrate LDH, which was later modified by anion exchange with linear and branched sodium alkyl sulfates having different alkyl chain lengths (nc = 6, 12 and 20. It was observed that, depending on the size of the surfactant alkyl chain, different degrees of polymer chain intercalation were achieved, which is a function of the interlayer distance of the organo-LDHs, of the packing level of the alkyl chains, and of the different interaction levels between the surfactant and the polymer chains. In particular, when the number of carbon atoms of the surfactant alkyl chain is larger than 12, the intercalation of polymer chains in the interlayer space and depression of the formation of large aggregates of organo-LDH platelets are favored. A remarkable improvement of the thermal-oxidative degradation was evidenced for all of the composites; whereas only a slight increase of the crystallization temperature and no significant changes of both melting temperature and degree of crystallinity were achieved. By thermodynamic mechanical analysis, it was evidenced that a softening of the matrix is may be due to the plasticizing effect of the surfactant.

  1. Fabrication and tribological properties of self-assembled monolayer of n-alkyltrimethoxysilane on silicon: Effect of SAM alkyl chain length

    Science.gov (United States)

    Huo, Lixia; Du, Pengcheng; Zhou, Hui; Zhang, Kaifeng; Liu, Peng

    2017-02-01

    It is well known that the self-assembled organic molecules on a solid surface exhibit the friction-reducing performance. However, the effect of the molecular size of the self-assembled organic molecules has not been established. In the present work, self-assembled monolayers (SAMs) of n-alkyltrimethoxysilanes with different alkyl chain lengths (C6, C12, or C18) were fabricated on silicon substrate. The water contact angles of the SAMs increased from 26.8° of the hydroxylated silicon substrate to near 60° after self-assembly. The atomic force microscopy (AFM) analysis results showed that the mean roughness (Ra) of the SAMs decreased with increasing the alkyl chain length. The tribological properties of the SAMs sliding against Al2O3 ball were evaluated on an UMT-2 tribometer, and the worn surfaces of the samples were analyzed by means of Nano Scratch Tester and surface profilometry. It was found that lowest friction coefficient and smallest width of wear were achieved with the SAMs of C12 alkyl chain (C12-SAM). The superior friction reduction and wear resistance of the SAMs in comparison with the bare silicon substrate are attributed to good adhesion of the self-assembled films to the substrate, especially the C12-SAM with desirable alkyl chain length.

  2. Effects of alkyl chain length and substituent pattern of fullerene bis-adducts on film structures and photovoltaic properties of bulk heterojunction solar cells.

    Science.gov (United States)

    Tao, Ran; Umeyama, Tomokazu; Kurotobi, Kei; Imahori, Hiroshi

    2014-10-08

    A series of alkoxycarbonyl-substituted dihydronaphthyl-based [60]fullerene bis-adduct derivatives (denoted as C2BA, C4BA, and C6BA with the alkyl chain of ethyl, n-butyl, and n-hexyl, respectively) have been synthesized to investigate the effects of alkyl chain length and substituent pattern of fullerene bis-adducts on the film structures and photovoltaic properties of bulk heterojunction polymer solar cells. The shorter alkyl chain length caused lower solubility of the fullerene bis-adducts (C6BA > C4BA > C2BA), thereby resulting in the increased separation difficulty of respective bis-adduct isomers. The device performance based on poly(3-hexylthiophene) (P3HT) and the fullerene bis-adduct regioisomer mixtures was enhanced by shortening the alkyl chain length. When using the regioisomerically separated fullerene bis-adducts, the devices based on trans-2 and a mixture of trans-4 and e of C4BA exhibited the highest power conversion efficiencies of ca. 2.4%, which are considerably higher than those of the C6BA counterparts (ca. 1.4%) and the C4BA regioisomer mixture (1.10%). The film morphologies as well as electron mobilities of the P3HT:bis-adduct blend films were found to affect the photovoltaic properties considerably. These results reveal that the alkyl chain length and substituent pattern of fullerene bis-adducts significantly influence the photovoltaic properties as well as the film structures of bulk heterojunction solar cells.

  3. Probing the Differential Tissue Distribution and Bioaccumulation Behavior of Per- and Polyfluoroalkyl Substances of Varying Chain-Lengths, Isomeric Structures and Functional Groups in Crucian Carp.

    Science.gov (United States)

    Shi, Yali; Vestergren, Robin; Nost, Therese Haugdahl; Zhou, Zhen; Cai, Yaqi

    2018-04-17

    Understanding the bioaccumulation mechanisms of per- and polyfluoroalkyl substances (PFASs) across different chain-lengths, isomers and functional groups represents a monumental scientific challenge with implications for chemical regulation. Here, we investigate how the differential tissue distribution and bioaccumulation behavior of 25 PFASs in crucian carp from two field sites impacted by point sources can provide information about the processes governing uptake, distribution and elimination of PFASs. Median tissue/blood ratios (TBRs) were consistently 90% of the amount of PFASs in the organism. Principal component analyses of TBRs and RBBs showed that the functional group was a relatively more important predictor of internal distribution than chain-length for PFASs. Whole body bioaccumulation factors (BAFs) for short-chain PFASs deviated from the positive relationship with hydrophobicity observed for longer-chain homologues. Overall, our results suggest that TBR, RBB, and BAF patterns were most consistent with protein binding mechanisms although partitioning to phospholipids may contribute to the accumulation of long-chain PFASs in specific tissues.

  4. Effect of stereochemistry, chain length and sequence pattern on antimicrobial properties of short synthetic β-sheet forming peptide amphiphiles.

    Science.gov (United States)

    Ong, Zhan Yuin; Cheng, Junchi; Huang, Yuan; Xu, Kaijin; Ji, Zhongkang; Fan, Weimin; Yang, Yi Yan

    2014-01-01

    In the face of mounting global antibiotics resistance, the identification and development of membrane-active antimicrobial peptides (AMPs) as an alternative class of antimicrobial agent have gained significant attention. The physical perturbation and disruption of microbial membranes by the AMPs have been proposed to be an effective means to overcome conventional mechanisms of drug resistance. Recently, we have reported the design of a series of short synthetic β-sheet folding peptide amphiphiles comprised of recurring (X1Y1X2Y2)n-NH2 sequences where X: hydrophobic amino acids, Y: cationic amino acids and n: number of repeat units. In efforts to investigate the effects of key parameters including stereochemistry, chain length and sequence pattern on antimicrobial effects, systematic d-amino acid substitutions of the lead peptides (IRIK)2-NH2 (IK8-all L) and (IRVK)3-NH2 (IK12-all L) were performed. It was found that the corresponding D-enantiomers exhibited stronger antimicrobial activities with minimal or no change in hemolytic activities, hence translating very high selectivity indices of 407.0 and >9.8 for IK8-all D and IK12-all D respectively. IK8-all D was also demonstrated to be stable to degradation by broad spectrum proteases trypsin and proteinase K. The membrane disrupting bactericidal properties of IK8-all D effectively prevented drug resistance development and inhibited the growth of various clinically isolated MRSA, VRE, Acinetobacter baumanni, Pseudomonas aeruginosa, Cryptococcus. neoformans and Mycobacterium tuberculosis. Significant reduction in intracellular bacteria counts was also observed following treatment with IK8-all D in the Staphylococcus. aureus infected mouse macrophage cell line RAW264.7 (P < 0.01). These results suggest that the d-amino acids substituted β-sheet forming peptide IK8-all D with its enhanced antimicrobial activities and improved protease stability, is a promising therapeutic candidate with potential to combat

  5. Photoluminescence and self-assembly of cesium lead halide perovskite nanocrystals: Effects of chain length of organic amines and reaction temperature

    Science.gov (United States)

    Yuan, Yi; Liu, Zheming; Liu, Zhenyang; Peng, Lan; Li, Yongjie; Tang, Aiwei

    2017-05-01

    All-inorganic halide perovskites have become one of the most prospective materials for lightening and display technology due to their color-tunable and narrow-band emission. Herein, we have systematically studied the effects of organic amines with different hydrocarbon chain length on the optical properties and morphology as well as the crystal structure of colloidal CsPbBr3 nanocrystals (NCs), which were synthesized in the presence of oleic acid (OA) and organic amines by using a simple hot-injection approach. The hydrocarbon chain length has shown an independent correlation to the morphology and crystal structure of the as-obtained CsPbBr3 NCs at 160 °C, but their optical properties can be affected to some extent. The photoluminescence quantum yields (PLQYs) of the CsPbBr3 NCs synthesized in the presence of organic amines with long carbon chain length are generally in the range of 55-80% for different reaction time, but the PLQYs of less than 20% are obtained for the products synthesized in the presence of octylamine (OTAm) with short carbon chain length. The effects of the reaction temperature on the optical properties, size and crystal structure of the CsPbBr3 NCs synthesized in the presence of cetylamine (CTAm) are studied. Interestingly, some nanoplates also appear in these CsPbBr3 NCs obtained at relatively low temperatures (120 and 140 °C), which have a strong tendency to self-assemble into face-to-face nanostructures. Such a similar self-assembly behavior is also observed in the product synthesized in the presence of oleylamine (OLAm), but only flat nanoplates are observed in the products in the presence of OTAm at 120 °C. The results indicate that the lower reaction temperature and hydrocarbon chain length of the organic ligands play a significant role in the self-assembly of CsPbBr3 NCs. This work opens up an alternative approach to controllable-synthesis of perovskite NCs through varying the carbon chain length of organic surfactants, and enlightens

  6. Effects of molecular and lattice structure on the thermal behaviours of some long chain length potassium(I) n-alkanoates

    Science.gov (United States)

    Nelson, Peter N.; Ellis, Henry A.; Taylor, Richard A.

    2014-01-01

    Lattice structures and thermal behaviours for some long chain potassium carboxylates (nc = 8-18, inclusive) are investigated using Fourier Transform Infrared spectroscopy, X-ray Powder Diffraction, Solid State spin decoupled 13C NMR spectroscopy, Differential Scanning Calorimetry and Thermogravimetry. The measurements show that the carboxyl groups are coordinated to potassium atoms via asymmetric chelating bidentate bonding, with extensive carboxyl intermolecular interactions to yield tetrahedral metal centers, irrespective of chain length. Furthermore, the hydrocarbon chains are crystallized in the fully extended all-trans configuration and are arranged as non-overlapping lamellar bilayer structures with closely packed methyl groups from opposite layers. Additionally, odd-even alternation, observed in density and methyl group chemical shift, is ascribed to the relative vertical distances between layers in the bilayer, that are not in the same plane. Therefore, for even chain homologues, where this distances is less than for odd chain adducts, more intimate packing is indicated. The phase sequences for all compounds show several reversible crystal-crystal transition associated with kinetically controlled gauche-trans isomerism of the polymethylene chains which undergo incomplete fusion when heated to the melt. The compounds degrade above 785 K to yield carbon dioxide, water, potassium oxide and an alkene.

  7. The critical main-chain length for helix formation in water: determined in a peptide series with alternating Aib and Ala residues exclusively and detected with ECD spectroscopy.

    Science.gov (United States)

    Longo, Edoardo; Moretto, Alessandro; Formaggio, Fernando; Toniolo, Claudio

    2011-10-01

    Critical main-chain length for peptide helix formation in the crystal (solid) state and in organic solvents has been already reported. In this short communication, we describe our results aiming at assessing the aforementioned parameter in water solution. To this goal, we synthesized step-by-step by solution procedures a complete series of N-terminally acetylated, C-terminally methoxylated oligopeptides, characterized only by alternating Aib and Ala residues, from the dimer to the nonamer level. All these compounds were investigated by electronic circular dichroism in the far-UV region in water solution as a function of chemical structure, namely presence/absence of an ester moiety or a negative charge at the C-terminus, and temperature. We find that the critical main-chain lengths for 3(10)- and α-helices, although still formed to a limited extent, in aqueous solution are six and eight residues, respectively. © 2011 Wiley-Liss, Inc.

  8. Studies on the solvation dynamics of coumarin 153 in 1-ethyl-3-methylimidazolium alkylsulfate ionic liquids: dependence on alkyl chain length.

    Science.gov (United States)

    Das, Sudhir Kumar; Sarkar, Moloy

    2012-08-06

    Steady-state and time-resolved fluorescence behavior of coumarin 153 (C153) is investigated in a series of 1-ethyl-3-methylimidazolium alkylsulfate ([C(2)mim][C(n)OSO(3)]) ionic liquids differing only in the length of the linear alkyl chain (n = 4, 6, and 8) in the anion. The aim of the present study is to understand the role of alkyl chain length in solute rotation and solvation dynamics of C153 in these ionic liquids. The blueshift observed in the steady-state absorption and emission maxima of C153 on going from the C(4)OSO(3) to the C(8)OSO(3) system indicates increasing nonpolar character of the microenvironment of the solute with increasing length of the alkyl side chain of the anion of the ionic liquids. The average solvation time is also found to increase on changing the substituent from butyl to octyl, and this is attributed to the increase in the bulk viscosity of the ILs. A steady blueshift of the time-zero maximum of the fluorescence spectrum with increasing alkyl chain length also indicates that the probe molecule experiences a less polar environment in the early part of the dynamics. Rotational dynamics of C153 are also analyzed by using the Stokes-Einstein-Debye (SED), Gierer-Wirtz (GW), and Dote-Kivelson-Schwartz (DKS) theories. Analyses of the results seem to suggest decoupling of the rotational motion of the probe from solvent viscosity. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Spacer grid for fuel elements

    International Nuclear Information System (INIS)

    Hensolt, T.; Huenner, M.; Rau, P.; Veca, A.

    1978-01-01

    The spacer grid for fuel elements of a gas-cooled fast breeder reactor (but also for PWRs and BWRs) consists of a lattice field with dodecagonal meshes. These meshes are formed by three each adjacent hexagons grouped arround a central axis. The pairs of legs extending into the dodecagon and being staggered by 120 0 are designed as knubs with inclined abutting surfaces for the fuel rods. By this means there is formed a three-point bearing for centering the fuel rods. The spacer grid mentioned above is rough-worked from a single disc- resp. plate-shaped body (unfinished piece). (DG) [de

  10. Spacer grid for fuel elements

    International Nuclear Information System (INIS)

    Hensolt, T.; Huenner, M.; Rau, P.; Veca, A.

    1980-01-01

    The spacer grid for fuel elements of a gas-cooled fast breeder reactor (but also for PWRs and BWRs) consists of a lattice field with dodecagonal meshes. These meshes are formed by three each adjacent hexagons grouped arround a central axis. The pairs of legs extending into the dodecagon and being staggered by 120 are designed as knubs with inclined abutting surfaces for the fuel rods. By this means there is formed a three-point bearing for centering the fuel rods. The spacer grid mentioned above is rough-worked from a single disc- resp. plate-shaped body (unfinished piece). (orig.)

  11. Hot fuel examination facility element spacer wire-wrap machine

    International Nuclear Information System (INIS)

    Tobias, D.A.; Sherman, E.K.

    1989-01-01

    Nondestructive examinations of irradiated experimental fuel elements conducted in the Argonne National Laboratory Hot Fuel Examination Facility/North (HFEF/N) at the Idaho National Engineering Laboratory include laser and contact profilometry (element diameter measurements), electrical eddy-current testing for cladding and thermal bond defects, bow and length measurements, neutron radiography, gamma scanning, remote visual exam, and photography. Profilometry was previously restricted to spiral profilometry of the element to prevent interference with the element spacer wire wrapped in a helix about the Experimental Breeder Reactor II (EBR-II)-type fuel element from end to end. By removing the spacer wire prior to conducting profilometry examination, axial profilometry techniques may be used, which are considerably faster than spiral techniques and often result in data acquisition more important to experiment sponsors. Because the element must often be reinserted into the nuclear reactor (EBR-II) for additional irradiation, however, the spacer wire must be reinstalled on the highly irradiated fuel element by remote means after profilometry of the wireless elements. The element spacer wire-wrap machine developed at HFEF is capable of helically wrapping fuel elements with diameters up to 1.68 cm (0.660 in.) and 2.44-m (96-in.) lengths. The machine can accommodate almost any desired wire pitch length by simply inserting a new wrapper gear module

  12. Effect of the Alkyl Chain Length Incorporated into Donor Part on the Optoelectronic Properties of the Carbazole Based Dyes: Theoretical Study

    Directory of Open Access Journals (Sweden)

    Souad El Mzioui

    2017-12-01

    Full Text Available In this paper, we report a theoretical study using density functional theory (DFT and time-dependent (TD-DFT for R-D-π-A systems with various alkyl chains (R. Results show that the LUMO of the dye lies above the semiconductor conduction band, promoting the injection of electrons; the lower HOMO level promotes dye regeneration. The incorporation of methyl chain (CH3 has a significant reduction in the gap energy, improved red-shift absorption spectrum and increase the molar extinction coefficient at the maximum absorption wavelength compared to D. While, the increase in alkyl chain length from C2H5 to C6H13 present a relatively reduce of gap energies, low effect on the wavelength (438 nm and converged excitation energies. DOI: http://dx.doi.org/10.17807/orbital.v9i5.1003 

  13. Ultrasonic Relaxation Study of 1-Alkyl-3-methylimidazolium-Based Room-Temperature Ionic Liquids: Probing the Role of Alkyl Chain Length in the Cation.

    Science.gov (United States)

    Zorębski, Michał; Zorębski, Edward; Dzida, Marzena; Skowronek, Justyna; Jężak, Sylwia; Goodrich, Peter; Jacquemin, Johan

    2016-04-14

    Ultrasound absorption spectra of four 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imides were determined as a function of the alkyl chain length on the cation from 1-propyl to 1-hexyl from 293.15 to 323.15 K at ambient pressure. Herein, the ultrasound absorption measurements were carried out using a standard pulse technique within a frequency range from 10 to 300 MHz. Additionally, the speed of sound, density, and viscosity have been measured. The presence of strong dissipative processes during the ultrasound wave propagation was found experimentally, i.e., relaxation processes in the megahertz range were observed for all compounds over the whole temperature range. The relaxation spectra (both relaxation amplitude and relaxation frequency) were shown to be dependent on the alkyl side chain length of the 1-alkyl-3-methylimidazolium ring. In most cases, a single-Debye model described the absorption spectra very well. However, a comparison of the determined spectra with the spectra of a few other imidazolium-based ionic liquids reported in the literature (in part recalculated in this work) shows that the complexity of the spectra increases rapidly with the elongation of the alkyl chain length on the cation. This complexity indicates that both the volume viscosity and the shear viscosity are involved in relaxation processes even in relatively low frequency ranges. As a consequence, the sound velocity dispersion is present at relatively low megahertz frequencies.

  14. Bond length and electric current oscillation of long linear carbon chains: Density functional theory, MpB model, and quantum spin transport studies

    International Nuclear Information System (INIS)

    Oeiras, R. Y.; Silva, E. Z. da

    2014-01-01

    Carbon linear atomic chains attached to graphene have experimentally been produced. Motivated by these results, we study the nature of the carbon bonds in these nanowires and how it affects their electrical properties. In the present study we investigate chains with different numbers of atoms and we observe that nanowires with odd number of atoms present a distinct behavior than the ones with even numbers. Using graphene nanoribbons as leads, we identify differences in the quantum transport of the chains with the consequence that even and odd numbered chains have low and high electrical conduction, respectively. We also noted a dependence of current with the wire size. We study this unexpected behavior using a combination of first principles calculations and simple models based on chemical bond theory. From our studies, the electrons of carbon nanowires present a quasi-free electron behavior and this explains qualitatively the high electrical conduction and the bond lengths with unexpected values for the case of odd nanowires. Our study also allows the understanding of the electric conduction dependence with the number of atoms and their parity in the chain. In the case of odd number chains a proposed π-bond (MpB) model describes unsaturated carbons that introduce a mobile π-bond that changes dramatically the structure and transport properties of these wires. Our results indicate that the nature of bonds plays the main role in the oscillation of quantum electrical conduction for chains with even and odd number of atoms and also that nanowires bonded to graphene nanoribbons behave as a quasi-free electron system, suggesting that this behavior is general and it could also remain if the chains are bonded to other materials

  15. Equivalent chain lengths of all C4-C23 saturated monomethyl branched fatty acid methyl esters on methylsilicone OV-1 stationary phase.

    Science.gov (United States)

    Kubinec, Róbert; Blaško, Jaroslav; Górová, Renáta; Addová, Gabriela; Ostrovský, Ivan; Amann, Anton; Soják, Ladislav

    2011-04-01

    Isomer mixtures of monomethyl branched saturated C7-C23 fatty acid methyl esters (FAME) were prepared by performing a methylene insertion reaction to the straight chain FAME and this study model was completed by using commercially available standards of C4-C7 FAME. The equivalent chain lengths (ECL) of all 220 C4-C23 monomethyl branched FAME on OV-1 stationary phase were measured, achieving an average repeatability of ±0.0004 ECL units. The monomethyl branched FAME was identified by GC on the basis of regularity of the fractional chain lengths (FCL) dependence on the number of carbon atoms (C(z)) of individual homologous series of methyl 2-, 3-, …, 21-FAME. The prediction of retention of the first homologues, having the new position of methyl group beginning at higher carbon atoms number, and analogously for the second, third, fourth, and other members of the homologous series, allowed the dependence FCL=f(C(z)) for the first and subsequent members of beginning homologous of monomethyl derivatives of FAME. The identification was confirmed by mass spectrometry. All of the methyl isomers of FAME, which could not be completely separated by gas chromatography due to having a methyl group in surroundings of the middle of the carbon chain, were resolved by mass spectrometry using deconvolution in a SIM-mode. Measured gas chromatographic and mass spectrometric data were applied for identification of the monomethyl branched saturated FAME in tongue coating. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Is DNA a worm-like chain in Couette flow? In search of persistence length, a critical review.

    Science.gov (United States)

    Rittman, Martyn; Gilroy, Emma; Koohya, Hashem; Rodger, Alison; Richards, Adair

    2009-01-01

    Persistence length is the foremost measure of DNA flexibility. Its origins lie in polymer theory which was adapted for DNA following the determination of BDNA structure in 1953. There is no single definition of persistence length used, and the links between published definitions are based on assumptions which may, or may not be, clearly stated. DNA flexibility is affected by local ionic strength, solvent environment, bound ligands and intrinsic sequence-dependent flexibility. This article is a review of persistence length providing a mathematical treatment of the relationships between four definitions of persistence length, including: correlation, Kuhn length, bending, and curvature. Persistence length has been measured using various microscopy, force extension and solution methods such as linear dichroism and transient electric birefringence. For each experimental method a model of DNA is required to interpret the data. The importance of understanding the underlying models, along with the assumptions required by each definition to determine a value of persistence length, is highlighted for linear dichroism data, where it transpires that no model is currently available for long DNA or medium to high shear rate experiments.

  17. Nighttime oxidation of surfactants at the air-water interface: effects of chain length, head group and saturation

    Science.gov (United States)

    Sebastiani, Federica; Campbell, Richard A.; Rastogi, Kunal; Pfrang, Christian

    2018-03-01

    Reactions of the key atmospheric nighttime oxidant NO3 with organic monolayers at the air-water interface are used as proxies for the ageing of organic-coated aqueous aerosols. The surfactant molecules chosen for this study are oleic acid (OA), palmitoleic acid (POA), methyl oleate (MO) and stearic acid (SA) to investigate the effects of chain length, head group and degree of unsaturation on the reaction kinetics and products formed. Fully and partially deuterated surfactants were studied using neutron reflectometry (NR) to determine the reaction kinetics of organic monolayers with NO3 at the air-water interface for the first time. Kinetic modelling allowed us to determine the rate coefficients for the oxidation of OA, POA and MO monolayers to be (2.8±0.7) × 10-8, (2.4±0.5) × 10-8and (3.3±0.6) × 10-8 cm2 molecule-1 s-1 for fitted initial desorption lifetimes of NO3 at the closely packed organic monolayers, τd, NO3, 1, of 8.1±4.0, 16±4.0 and 8.1±3.0 ns, respectively. The approximately doubled desorption lifetime found in the best fit for POA compared to OA and MO is consistent with a more accessible double bond associated with the shorter alkyl chain of POA facilitating initial NO3 attack at the double bond in a closely packed monolayer. The corresponding uptake coefficients for OA, POA and MO were found to be (2.1±0.5) × 10-3, (1.7±0.3) × 10-3 and (2.1±0.4) × 10-3, respectively. For the much slower NO3-initiated oxidation of the saturated surfactant SA we estimated a loss rate of approximately (5±1) × 10-12 cm2 molecule-1 s-1, which we consider to be an upper limit for the reactive loss, and estimated an uptake coefficient of ca. (5±1) × 10-7. Our investigations demonstrate that NO3 will contribute substantially to the processing of unsaturated surfactants at the air-water interface during nighttime given its reactivity is ca. 2 orders of magnitude higher than that of O3. Furthermore, the relative contributions of NO3 and O3 to the oxidative

  18. Nighttime oxidation of surfactants at the air–water interface: effects of chain length, head group and saturation

    Directory of Open Access Journals (Sweden)

    F. Sebastiani

    2018-03-01

    Full Text Available Reactions of the key atmospheric nighttime oxidant NO3 with organic monolayers at the air–water interface are used as proxies for the ageing of organic-coated aqueous aerosols. The surfactant molecules chosen for this study are oleic acid (OA, palmitoleic acid (POA, methyl oleate (MO and stearic acid (SA to investigate the effects of chain length, head group and degree of unsaturation on the reaction kinetics and products formed. Fully and partially deuterated surfactants were studied using neutron reflectometry (NR to determine the reaction kinetics of organic monolayers with NO3 at the air–water interface for the first time. Kinetic modelling allowed us to determine the rate coefficients for the oxidation of OA, POA and MO monolayers to be (2.8±0.7 × 10−8, (2.4±0.5 × 10−8and (3.3±0.6 × 10−8 cm2 molecule−1 s−1 for fitted initial desorption lifetimes of NO3 at the closely packed organic monolayers, τd, NO3, 1, of 8.1±4.0, 16±4.0 and 8.1±3.0 ns, respectively. The approximately doubled desorption lifetime found in the best fit for POA compared to OA and MO is consistent with a more accessible double bond associated with the shorter alkyl chain of POA facilitating initial NO3 attack at the double bond in a closely packed monolayer. The corresponding uptake coefficients for OA, POA and MO were found to be (2.1±0.5 × 10−3, (1.7±0.3 × 10−3 and (2.1±0.4 × 10−3, respectively. For the much slower NO3-initiated oxidation of the saturated surfactant SA we estimated a loss rate of approximately (5±1 × 10−12 cm2 molecule−1 s−1, which we consider to be an upper limit for the reactive loss, and estimated an uptake coefficient of ca. (5±1 × 10−7. Our investigations demonstrate that NO3 will contribute substantially to the processing of unsaturated surfactants at the air–water interface during nighttime given its reactivity is ca. 2 orders of magnitude higher

  19. Nuclear reactor spacer assembly

    International Nuclear Information System (INIS)

    Anthony, A.J.; Groves, M.D.

    1979-01-01

    A fuel assembly for a nuclear reactor is disclosed wherein the fuel element receiving and supporting grid is comprised of a first metal, the guide tubes which pass through the grid assembly are comprised of a second metal and the grid is supported on the guide tubes by means of expanded sleeves located intermediate the grid and guide tubes. The fuel assembly is fabricated by inserting the sleeves, of initial outer diameter commensurate with the guide tube outer diameters, through the holes in the grid assembly provided for the guide tubes and thereafter expanding the sleeves radially outwardly along their entire length such that the guide tubes can subsequently be passed through the sleeves. The step of radial expansion, as a result of windows provided in the sleeves having dimensions commensurate with the geometry of the grid, mechanically captures the grid and simultaneously preloads the sleeve against the grid whereby relative motion between the grid and guide tube will be precluded

  20. Critical determinant of intestinal permeability and oral bioavailability of pegylated all trans-retinoic acid prodrug-based nanomicelles: Chain length of poly (ethylene glycol) corona.

    Science.gov (United States)

    Li, Zhenbao; Han, Xiaopeng; Zhai, Yinglei; Lian, He; Zhang, Dong; Zhang, Wenjuan; Wang, Yongjun; He, Zhonggui; Liu, Zheng; Sun, Jin

    2015-06-01

    Pegylation method is widely used to prolong the blood circulation time of proteins and nanoparticles after intravenous administration, but the effect of surface poly (ethylene glycol) (PEG) chain length on oral absorption of the pegylated nanoparticles is poorly reported. The aim of our study was to investigate the influence of PEG corona chain length on membrane permeability and oral bioavailability of the amphiphilic pegylated prodrug-based nanomicelles, taking all trans-retinoic acid (ATRA) as a model drug. The amphiphilic ATRA-PEG conjugates were synthesized by esterification reaction between all trans-retinoic acid and mPEGs (mPEG500, mPEG1000, mPEG2000, and mPEG5000). The conjugates could self-assemble in aqueous medium to form nanomicelles by emulsion-solvent evaporation method. The resultant nanomicelles were in spherical shape with an average diameter of 13-20 nm. The drug loading efficiency of ATRA-PEG500, ATRA-PEG1000, ATRA-PEG2000, and ATRA-PEG5000 was about 38.4, 26.6, 13.1, and 5.68 wt%, respectively. With PEG chain length ranging from 500 to 5000, ATRA-PEG nanomicelles exhibited a bell shape of chemical stability in different pH buffers, intestinal homogenate and plasma. More importantly, they were all rapidly hydrolyzed into the parent drug in hepatic homogenate, with the half-time values being 0.3-0.4h. In comparison to ATRA solution and ATRA prodrug-based nanomicelles, ATRA-PEG1000 showed the highest intestinal permeability. After oral administration, ATRA-PEG2000 and ATRA-PEG5000 nanomicelles were not nearly absorbed, while the oral bioavailability of ATRA-PEG500 and ATRA-PEG1000 demonstrated about 1.2- and 2.0-fold higher than ATRA solution. Our results indicated that PEG1000 chain length of ATRA-PEG prodrug nanomicelles has the optimal oral bioavailability probably due to improved stability and balanced mucus penetration capability and cell binding, and that the PEG chain length on a surface of nanoparticles cannot exceed a key threshold with

  1. Lipid membrane partitioning of lysolipids and fatty acids: Effects of membrane phase structure and detergent chain length

    DEFF Research Database (Denmark)

    Høyrup, Lise Pernille Kristine; Davidsen, Jesper; Jørgensen, Kent

    2001-01-01

    gel phase and at high temperatures in the disordered fluid phase of the phospholipid membrane vesicles. The long saturated acyl chains of the lysolipids and fatty acids varied from 10 to 16 carbon atoms and all titrations were performed below the critical micellar concentrations (cmc...... of magnitude higher when the saturated acyl chain of the detergents increases by two carbon atoms. The obtained partition coefficients are of importance in relation to a deeper understanding of the interplay between global aqueous and local membrane concentrations of the detergents and the functional influence...

  2. Novel extracellular medium-chain-length polyhydroxyalkanoate depolymerase from Streptomyces exfoliatus K10 DSMZ 41693

    DEFF Research Database (Denmark)

    Martinez, Virginia; de Santos, Patricia Gómez; García-Hidalgo, Javier

    2015-01-01

    reaction product. Markedly, PhaZSex2 is able to degrade functionalized polymers containing thioester groups in the side chain (PHACOS), releasing functional thioester-based monomers and oligomers demonstrating the potentiality of this novel biocatalyst for the industrial production of enantiopure (R)-3...

  3. Highly Grafted Polystyrene/polyvinylpyridine Polymer Gold Nanoparticles in a Good Solvent: Effects of Chain Length and Composition.

    Czech Academy of Sciences Publication Activity Database

    Posel, Zbyšek; Posocco, P.; Lísal, Martin; Fermeglia, M.; Pricl, S.

    2016-01-01

    Roč. 12, č. 15 (2016), s. 3600-3611 ISSN 1744-683X R&D Projects: GA ČR(CZ) GA13-02938S; GA MŠk LH12020 Institutional support: RVO:67985858 Keywords : block copolymers * chains * fiber optic sensors Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.889, year: 2016

  4. Revisit complexation between DNA and polyethylenimine — Effect of length of free polycationic chains on gene transfection

    DEFF Research Database (Denmark)

    Yue, Yanan; Jin, Fan; Deng, Rui

    2011-01-01

    Our revisit of the complexation between DNA and polyethylenimine (PEI) by using a combination of laser light scattering and gel electrophoresis confirms that nearly all the DNA chains are complexed with PEI to form polyplexes when the molar ratio of nitrogen from PEI to phosphate from DNA (N:P) r...

  5. Influence of alkyl chain length and anion species on ionic liquid structure at the graphite interface as a function of applied potential

    International Nuclear Information System (INIS)

    Li, Hua; Wood, Ross J; Atkin, Rob; Endres, Frank

    2014-01-01

    Atomic force microscopy (AFM) force measurements elucidate the effect of cation alkyl chain length and the anion species on ionic liquid (IL) interfacial structure at highly ordered pyrolytic graphite (HOPG) surfaces as a function of potential. Three ILs are examined: 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([HMIM] FAP), 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([EMIM] FAP), and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM] TFSA). The step-wise force-distance profiles indicate the ILs adopt a multilayered morphology near the surface. When the surface is biased positively or negatively versus Pt quasireference electrode, both the number of steps, and the force required to rupture each step increase, indicating stronger interfacial structure. At all potentials, push-through forces for [HMIM] FAP are the highest, because the long alkyl chain results in strong cohesive interactions between cations, leading to well-formed layers that resist the AFM tip. The most layers are observed for [EMIM] FAP, because the C 2 chains are relatively rigid and the dimensions of the cation and anion are similar, facilitating neat packing. [EMIM] TFSA has the smallest push-through forces and fewest layers, and thus the weakest interfacial structure. Surface-tip attractive forces are measured for all ILs. At the same potential, the attractions are the strongest for [EMIM] TFSA and the weakest for [HMIM] FAP because the interfacial layers are better formed for the longer alkyl chain cation. This means interfacial forces are stronger, which masks the weak attractive forces. (paper)

  6. Effects of Chain Length and Degree of Unsaturation of Fatty Acids on Structure and in Vitro Digestibility of Starch-Protein-Fatty Acid Complexes.

    Science.gov (United States)

    Zheng, Mengge; Chao, Chen; Yu, Jinglin; Copeland, Les; Wang, Shuo; Wang, Shujun

    2018-02-28

    The effects of chain length and degree of unsaturation of fatty acids (FAs) on structure and in vitro digestibility of starch-protein-FA complexes were investigated in model systems. Studies with the rapid visco analyzer (RVA) showed that the formation of ternary complex resulted in higher viscosities than those of binary complex during the cooling and holding stages. The results of differential scanning calorimetry (DSC), Raman, and X-ray diffraction (XRD) showed that the structural differences for ternary complexes were much less than those for binary complexes. Starch-protein-FA complexes presented lower in vitro enzymatic digestibility compared with starch-FAs complexes. We conclude that shorter chain and lower unsaturation FAs favor the formation of ternary complexes but decrease the thermal stability of these complexes. FAs had a smaller effect on the ordered structures of ternary complexes than on those of binary complexes and little effect on enzymatic digestibility of both binary and ternary complexes.

  7. Diversity of the marine picocyanobacteria Prochlorococcus and Synechococcus assessed by terminal restriction fragment length polymorphisms of 16S-23S rRNA internal transcribed spacer sequences Diversidad de las picocianobacterias marinas Prochlorococcus y Synechococcus por medio de polimorfismos de longitud de fragmentos de restricción terminal en secuencias del espaciador transcrito interno del ARNr 16S - 23S

    Directory of Open Access Journals (Sweden)

    PARIS LAVIN

    2008-12-01

    Full Text Available In order to assess the appropriateness of the use of internal transcribed spacer (ITS sequences for the study of population genetics of marine cyanobacteria, we amplified and cloned the 16S rRNA gene plus the 16S-23S ITS regions of six strains of Prochlorococcus and Synechococcus. We analyzed them by denaturing gradient gel electrophoresis (DGGE and terminal restriction fragment length polymorphisms (T-RFLP. When using the standard application of these techniques, we obtained more than one band or terminal restriction fragment (T-RF per strain or cloned sequence. Reports in literature have suggested that these anomalies can result from the formation of secondary structures. Secondary structures of the ITS sequences of Prochlorococcus and Synechococcus strains were computationally modelled at the different temperatures that were used during the polymerase chain reaction (PCR. Modelling results predicted the existence of hairpin loops that would still be present at the extensión temperature; it is likely that these loops produced incomplete and single stranded PCR products. We modified the standard T-RFLP procedure by adding the labelled ITS primer in the last two cycles of the PCR reaction; this resulted, in most cases, in only one T-RF per ribotype. Application of this technique to a natural picoplankton community in marine waters off northern Chile, showed that it was possible to identify the presence, and determine the relative abundance, of several phylogenetic lineages within the genera Prochlorococcus and Synechococcus inhabiting the euphotic zone. Phylogenetic analysis of ITS sequences obtained by cloning and sequencing DNA from the same sample confirmed the presence of the different genotypes. With the proposed modification, T-RFLP profiles should therefore be suitable for studying the diversity of natural populations of cyanobacteria, and should become an important tool to study the factors influencing the genetic structure and

  8. Analysis of the first and second internal transcribed spacer sequences of the ribosomal DNA in Biomphalaria tenagophila complex (Mollusca: Planorbidae

    Directory of Open Access Journals (Sweden)

    Teofânia HDA Vidigal

    2004-03-01

    Full Text Available The first and second internal transcribed spacer regions (ITS1 and ITS2 of the ribosomal DNA of Biomphalaria tenagophila complex (B. tenagophila, B. occidentalis, and B. t. guaibensis were sequenced and compared. The alignment lengths of these regions were about 655 bp and 481 bp, respectively. Phylogenetic relationships among the Biomphalaria species were inferred by Maximum Parsimony and Neighbor-joining methods. The phylogenetic trees produced, in most of the cases, were in accordance with morphological systematics and other molecular data previously obtained by polymerase chain reaction and restriction fragment length polymorphism analysis. The present results provide support for the proposal that B. tenagophila represents a complex comprising B. tenagophila, B. occidentalis and B. t. guaibensis.

  9. Critical effects of alkyl chain length on fibril structures in benzene-trans(RR)- or (SS)-N,N'-alkanoyl-1,2-diaminocyclohexane gels.

    Science.gov (United States)

    Sato, Hisako; Nakae, Takahiro; Morimoto, Kazuya; Tamura, Kenji

    2012-02-28

    Vibrational circular dichroism (VCD) spectra were recorded on benzene-d(6) gels formed by chiral low molecular mass gelators (LMGs), trans(RR)- or trans(SS)-N,N'-alkanoyl-1,2-diaminocyclohexane (denoted by RR-C(n) or SS-C(n), respectively; n = the number of carbon atoms in an introduced alkanoyl group). Attention was focused on the effects of alkyl chain length on the structures of the gels. When n was changed from 6 to 12, the signs of the coupled peaks around 1550 cm(-1) in the VCD spectra, which were assigned to the symmetric and asymmetric C=O stretching vibrations from the higher to lower wavenumber, respectively, critically depended on the alkyl chain length. In the case of RR-C(n), for example, the signs of the couplet were plus and minus for n = 8, 9, 10 and 12, while the signs of the same couplet were reversed for n = 6 and 7. The conformations of LMGs in fibrils were determined by comparing the observed IR and VCD spectra with those calculated for a monomeric molecule. The observed reversal of signs in the C=O couplet was rationalized in terms of the different modes of hydrogen bonding. In the case of C(8), C(9), C(10) and C(12), gelator molecules were stacked with their cyclohexyl rings in parallel, forming double anti-parallel chains of intermolecular hydrogen bonds using two pairs of >NH and >C=O groups. In case of C(6) and C(7), gelator molecules were stacked through a single chain of intermolecular hydrogen bonds using a pair of >NH and >C=O groups. The remaining pair of >NH and >C=O groups formed an intramolecular hydrogen bond.

  10. Photo-Induced Phase Transitions to Liquid Crystal Phases: Influence of the Chain Length from C8E4 to C14E4

    Directory of Open Access Journals (Sweden)

    Simone Techert

    2009-09-01

    Full Text Available Photo-induced phase transitions are characterized by the transformation from phase A to phase B through the absorption of photons. We have investigated the mechanism of the photo-induced phase transitions of four different ternary systems CiE4/alkane (i with n = 8, 10, 12, 14; cyclohexane/H2O. We were interested in understanding the effect of chain length increase on the dynamics of transformation from the microemulsion phase to the liquid crystal phase. Applying light pump (pulse/x-ray probe (pulse techniques, we could demonstrate that entropy and diffusion control are the driving forces for the kind of phase transition investigated.

  11. Flow behaviour of inulin-milk beverages: Influence of inulin chain length and of milk fat content

    OpenAIRE

    Villegas, Beatriz; Costell, Elvira

    2003-01-01

    Inulin is used either as a macronutrient substitute or as a supplement added in foods mainly for its nutritional properties. Chemically, inulin consists of a long chain made up of fructose molecules and one glucose molecule at one end. The fructose molecules are connected by β-(2-1) bonds and the last fructose is linked with a glucose by an α-(1-2) bond as in sucrose [1, 2]. The average molecular weight and degree of polymerisation of inulin depend on the source of inulin, the time of harvest...

  12. Numerical investigation on practicability of reducing MCST by using grid spacer in a tight rod bundle

    International Nuclear Information System (INIS)

    Zhu, Xiaojing; Morooka, Shinichi; Oka, Yoshiaki

    2014-01-01

    Highlights: • Standard grid spacer design causes decreased heat transfer in a tight rod bundle. • Heat transfer is greatly enhanced by flow-enhancing features. • Swirling flow adversely affects the heat transfer downstream of grid spacer. • Enhanced heat transfer by existing grid spacer is limited in a short region. • Improved grid spacer can effectively reduce MCST. - Abstract: The numerical investigation was carried out to reveal the practicability of reducing the maximum cladding surface temperature (MCST) within the inner sub-channel of a tight, hexagon rod bundle using commercial CFD code STAR CCM+ 6.04. The special heat transfer and pressure drop characteristics caused by four existing grid spacer designs were discussed in detail by analyzing the effects of grid strap length, different flow enhancing features and different Reynolds numbers. It was found that the local heat transfer within the grid strap is greatly enhanced due to the raised flow velocity. Both the standard grid spacer and the grid spacer with split-vanes cause decreased heat transfer in the downstream region. The friction drag is very influential in the tight rod bundle and can eliminate the positive effect of flow blockage on the heat transfer performance. The grid spacer with flow blockage discs induces relatively good heat transfer performance and higher pressure drop within sub-channels, indicating a tradeoff between the heat transfer augmentation and the pressure drop. The combination of multiple existing grid spacers can reduce the MCST to a certain level, but the corresponding disadvantages cannot be ignored. The improved grid spacer design was proposed based on the overall considerations of heat transfer and pressure drop characteristics and has been proved more suitable to widely reduce MCST for SCWR than any other grid spacer designs involved in present study

  13. Solute transport in a single fracture involving an arbitrary length decay chain with rock matrix comprising different geological layers.

    Science.gov (United States)

    Mahmoudzadeh, Batoul; Liu, Longcheng; Moreno, Luis; Neretnieks, Ivars

    2014-08-01

    A model is developed to describe solute transport and retention in fractured rocks. It accounts for advection along the fracture, molecular diffusion from the fracture to the rock matrix composed of several geological layers, adsorption on the fracture surface, adsorption in the rock matrix layers and radioactive decay-chains. The analytical solution, obtained for the Laplace-transformed concentration at the outlet of the flowing channel, can conveniently be transformed back to the time domain by the use of the de Hoog algorithm. This allows one to readily include it into a fracture network model or a channel network model to predict nuclide transport through channels in heterogeneous fractured media consisting of an arbitrary number of rock units with piecewise constant properties. More importantly, the simulations made in this study recommend that it is necessary to account for decay-chains and also rock matrix comprising at least two different geological layers, if justified, in safety and performance assessment of the repositories for spent nuclear fuel. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Critical Length Criterion and the Arc Chain Model for Calculating the Arcing Time of the Secondary Arc Related to AC Transmission Lines

    International Nuclear Information System (INIS)

    Cong Haoxi; Li Qingmin; Xing Jinyuan; Li Jinsong; Chen Qiang

    2015-01-01

    The prompt extinction of the secondary arc is critical to the single-phase reclosing of AC transmission lines, including half-wavelength power transmission lines. In this paper, a low-voltage physical experimental platform was established and the motion process of the secondary arc was recorded by a high-speed camera. It was found that the arcing time of the secondary arc rendered a close relationship with its arc length. Through the input and output power energy analysis of the secondary arc, a new critical length criterion for the arcing time was proposed. The arc chain model was then adopted to calculate the arcing time with both the traditional and the proposed critical length criteria, and the simulation results were compared with the experimental data. The study showed that the arcing time calculated from the new critical length criterion gave more accurate results, which can provide a reliable criterion in term of arcing time for modeling and simulation of the secondary arc related with power transmission lines. (paper)

  15. Implementation of spacer therapy for acute asthma in children.

    LENUS (Irish Health Repository)

    Vandeleur, M

    2009-09-01

    The aim was to develop and implement an evidence based guideline for the treatment of acute asthma using a metered dose inhaler and spacer combination. Children admitted to Cork University Hospital Paediatric Department with acute asthma were identified during two identical 2 month seasonal periods before (2005) and after (2006) implementation of the new guidelines in September 2006. Pre-intervention and post-intervention audits by case note review were performed to determine the impact of and compliance with this evidence-based guideline emphasising patient assessment, spacer delivered bronchodilator and specific discharge criteria. Patients had similar characteristics during the two study periods. There was a raised threshold for admission after guideline implementation with 11\\/52 patients having mild exacerbations in 2006, compared to 21\\/36 in 2005. Duration of admission was less in the post-implementation group for equivalent exacerbation severity e.g. for moderate severity; 28 hours in 2005, 23 hours in 2006. Duration of bronchodilator therapy was shorter in 2006 and more likely to be given by spacer device earlier for equivalent levels of severity e.g. for moderate exacerbations, in 2006 the average length of salbutamol therapy was 18 hours with 12 hours by spacer device, in 2005 the average length of therapy was 25 hours with 3 hours by spacer. There was earlier initiation of oral corticosteroids; the average time to administration was 56 minutes in 2006 and 227 minutes in 2005. There was an improved documentation of asthma education in 2006 e.g. inhaler technique was reviewed in 37\\/52 in 2006, 21\\/35 in 2005 and better use of written action plans.

  16. Effect of temperature and chain length on the viscosity and surface tension of binary systems of N,N-dimethylformamide with 1-octanol, 1-nonanol and 1-decanol

    International Nuclear Information System (INIS)

    Mohammad, Abubaker A.; Alkhaldi, Khaled H.A.E.; AlTuwaim, Mohammad S.; Al-Jimaz, Adel S.

    2014-01-01

    Highlights: • Effect of temperature and chain length on η and σ of DMF + 1-alkanol binary systems. • Viscosity and surface tension were obtained. • Δη, Δσ and G ∗E were calculated using the experimental data. • H σ and S σ were determined using the surface tension data. • Semi-empirical relations were used to estimate the viscosity of liquid mixtures. - Abstract: Viscosity and surface tension of binary systems of N,N-dimethylformamide DMF with higher 1-alkanols (C 8 –C 10 ) were measured at atmospheric pressure and four different temperatures over the entire range of mole fraction. The experimental measurements were used to calculate the deviations in viscosity and surface tension. Furthermore, the excess Gibbs free energy of activation, surface enthalpy and surface entropy of the (DMF + 1-alkanols) binary mixtures were determined. In addition, the deviation and excess properties were fitted to the method of Redlich–Kister (R–K) polynomial. Viscosity data of the binary systems were correlated with three different expressions (Grunberg and Nissan, the three-body, and four-body McAllister). The effects of the chain length of the higher 1-alkanols and temperature were investigated

  17. Individual Impact of Distinct Polysialic Acid Chain Lengths on the Cytotoxicity of Histone H1, H2A, H2B, H3 and H4

    Directory of Open Access Journals (Sweden)

    Kristina Zlatina

    2017-12-01

    Full Text Available Neutrophils are able to neutralize pathogens by phagocytosis, by the release of antimicrobial components, as well as by the formation of neutrophil extracellular traps (NETs. The latter possibility is a DNA-meshwork mainly consisting of highly concentrated extracellular histones, which are not only toxic for pathogens, but also for endogenous cells triggering several diseases. To reduce the negative outcomes initiated by extracellular histones, different approaches like antibodies against histones, proteases, and the polysaccharide polysialic acid (polySia were discussed. We examined whether each of the individual histones is a binding partner of polySia, and analyzed their respective cytotoxicity in the presence of this linear homopolymer. Interestingly, all of the histones (H1, H2A, H2B, H3, and H4 seem to interact with α2,8-linked sialic acids. However, we observed strong differences regarding the required chain length of polySia to bind histone H1, H2A, H2B, H3, and H4. Moreover, distinct degrees of polymerization were necessary to act as a cytoprotective agent in the presence of the individual histones. In sum, the outlined results described polySia-based strategies to bind and/or to reduce the cytotoxicity of individual histones using distinct polySia chain length settings.

  18. Effect of Acylglycerol Composition and Fatty Acyl Chain Length on Lipid Digestion in pH-Stat Digestion Model and Simulated In Vitro Digestion Model.

    Science.gov (United States)

    Qi, Jin F; Jia, Cai H; Shin, Jung A; Woo, Jeong M; Wang, Xiang Y; Park, Jong T; Hong, Soon T; Lee, K-T

    2016-02-01

    In this study, a pH-stat digestion model and a simulated in vitro digestion model were employed to evaluate the digestion degree of lipids depending on different acylglycerols and acyl chain length (that is, diacylglycerol [DAG] compared with soybean oil representing long-chain triacylglycerol compared with medium-chain triacylglycerol [MCT]). In the pH-stat digestion model, differences were observed among the digestion degrees of 3 oils using digestion rate (k), digestion half-time (t1/2 ), and digestion extent (Φmax). The results showed the digestion rate order was MCT > soybean oil > DAG. Accordingly, the order of digestion half-times was MCT digestion model, digestion rates (k') and digestion half-times (t'1/2 ) were also obtained and the results showed a digestion rate order of MCT (k' = 0.068 min(-1) ) > soybean oil (k' = 0.037 min(-1) ) > DAG (k' = 0.024 min(-1) ). Consequently, the order of digestion half-times was MCT (t'1/2 = 10.20 min) digested faster than soybean oil, and that soybean oil was digested faster than DAG. © 2015 Institute of Food Technologists®

  19. Diacyltransferase Activity and Chain Length Specificity of Mycobacterium tuberculosis PapA5 in the Synthesis of Alkyl β-Diol Lipids

    Energy Technology Data Exchange (ETDEWEB)

    Touchette, Megan H.; Bommineni, Gopal R.; Delle Bovi, Richard J.; Gadbery, John; Nicora, Carrie D.; Shukla, Anil K.; Kyle, Jennifer E.; Metz, Thomas O.; Martin, Dwight W.; Sampson, Nicole S.; Miller, W. T.; Tonge, Peter J.; Seeliger, Jessica C.

    2015-09-08

    Although classified as Gram-positive bacteria, Corynebacterineae possess an asymmetric outer membrane that imparts structural and thereby physiological similarity to more distantly related Gram-negative bacteria. Like lipopolysaccharide in Gram-negative bacteria, lipids in the outer membrane of Corynebacterineae have been associated with the virulence of pathogenic species such as Mycobacterium tuberculosis (Mtb). For example, Mtb strains that lack long, branched-chain alkyl esters known as dimycocerosates (DIMs) are significantly attenuated in model infections. The resultant interest in the biosynthetic pathway of these unusual virulence factors has led to the elucidation of many of the steps leading to the final esterification of the alkyl beta-diol, phthiocerol, with branched-chain fatty acids know as mycocerosates. PapA5 is an acyltransferase implicated in these final reactions. We here show that PapA5 is indeed the terminal enzyme in DIM biosynthesis by demonstrating its dual esterification activity and chain-length preference using synthetic alkyl beta-diol substrate analogues. Applying these analogues to a series of PapA5 mutants, we also revise a model for the substrate binding within PapA5. Finally, we demonstrate that the Mtb Ser/Thr kinase PknB modifies PapA5 on three Thr residues, including two (T196, T198) located on an unresolved loop. These results clarify the DIM biosynthetic pathway and suggest possible mechanisms by which DIM biosynthesis may be regulated by the post-translational modification of PapA5.

  20. Suppression of subthreshold characteristics variation for junctionless multigate transistors using high-k spacers

    International Nuclear Information System (INIS)

    Lou, Haijun; Zhang, Baili; Li, Dan; Lin, Xinnan; He, Jin; Chan, Mansun

    2015-01-01

    In this work, the high-k spacer is proposed to suppress the subthreshold characteristics variation of junctionless multigate transistor (JMT) with non-ideal sidewall angle for the first time. It is demonstrated that the variation of subthreshold characteristics induced by the changing sidewall angle is efficiently suppressed by high-k spacers due to the enhanced corner effect through the fringe capacitance, and the electrostatic integrity of JMTs is also improved at sub-22 nm gate length. Two key parameters of high-k spacer, the thickness and length, have been optimized in terms of the suppression of subthreshold characteristics variation. Then their optimal values are proposed. The benefit of high-k spacer makes JMTs more scalable. (paper)

  1. Effect of alkyl chain length on the rotational diffusion of nonpolar and ionic solutes in 1-alkyl-3-methylimidazolium-bis(trifluoromethylsulfonyl)imides.

    Science.gov (United States)

    Gangamallaiah, V; Dutt, G B

    2013-10-10

    Rotational diffusion of a nonpolar solute 9-phenylanthracene (9-PA) and a cationic solute rhodamine 110 (R110) has been examined in a series of 1-alkyl-3-methylimidazolium (alkyl = octyl, decyl, dodecyl, tetradecyl, hexadecyl, and octadecyl) bis(trifluoromethylsulfonyl)imides to understand the influence of alkyl chain length on solute rotation. In this study, reorientation times (τr) have been measured as a function of viscosity (η) by varying the temperature (T) of the solvents. These results have been analyzed using the Stokes-Einstein-Debye (SED) hydrodynamic theory along with the ones obtained for the same solutes in 1-alkyl-3-methylimidazolium (alkyl = methyl, ethyl, propyl, butyl, and hexyl) bis(trifluoromethylsulfonyl)imides (Gangamallaiah and Dutt, J. Phys. Chem. B 2012, 116, 12819-12825). It has been noticed that the data for 9-PA and R110 follows the relation τr = A(η/T)(n) with A being the ratio of hydrodynamic volume of the solute to the Boltzmann constant and n = 1 as envisaged by the SED theory. However, upon increasing the alkyl chain length from methyl to octadecyl significant deviations from the SED theory have been observed especially from the octyl derivative onward. From methyl to octadecyl derivatives, the value of A decreases by a factor of 3 for both the solutes and n by a factor of 1.4 and 1.6 for 9-PA and R110, respectively. These observations have been rationalized by taking into consideration the organized structure of the ionic liquids, whose influence appears to be pronounced when the number of carbon atoms in the alkyl chain attached to the imidazolium cation exceeds eight.

  2. Oligothiophene-Indandione-Linked Narrow-Band Gap Molecules: Impact of π-Conjugated Chain Length on Photovoltaic Performance.

    Science.gov (United States)

    Komiyama, Hideaki; To, Takahiro; Furukawa, Seiichi; Hidaka, Yu; Shin, Woong; Ichikawa, Takahiro; Arai, Ryota; Yasuda, Takuma

    2018-04-04

    Solution-processed organic solar cells (OSCs) based on narrow-band gap small molecules hold great promise as next-generation energy-converting devices. In this paper, we focus on a family of A-π-D-π-A-type small molecules, namely, BDT- nT-ID ( n = 1-4) oligomers, consisting of benzo[1,2- b:4,5- b']dithiophene (BDT) as the central electron-donating (D) core, 1,3-indandione (ID) as the terminal electron-accepting (A) units, and two regioregular oligo(3-hexylthiophene)s ( nT) with different numbers of thiophene rings as the π-bridging units, and elucidate their structure-property-function relationships. The effects of the length of the π-bridging nT units on the optical absorption, thermal behavior, morphology, hole mobility, and OSC performance were systematically investigated. All oligomers exhibited broad and intense visible photoabsorption in the 400-700 nm range. The photovoltaic performances of bulk heterojunction OSCs based on BDT- nT-IDs as donors and a fullerene derivative as an acceptor were studied. Among these oligomers, BDT-2T-ID, incorporating bithiophene as the π-bridging units, showed better photovoltaic performance with a maximum power conversion efficiency as high as 6.9% under AM 1.5G illumination without using solvent additives or postdeposition treatments. These favorable properties originated from the well-developed interpenetrating network morphology of BDT-2T-ID, with larger domain sizes in the photoactive layer. Even though all oligomers have the same A-D-A main backbone, structural modulation of the π-bridging nT length was found to impact their self-organization and nanostructure formation in the solid state, as well as the corresponding OSC device performance.

  3. Two pion correlation from SPACER

    International Nuclear Information System (INIS)

    Csoergoe, T.; Zimanyi, J.; Pratt, S.

    1989-12-01

    The correlation function for neutral and negative pions produced in ultrarelativistic heavy ion collisions was calculated without free parameters based on a space-time version of the LUND model, called SPACER: Simulation of Phase space distribution of Atomic nuclear Collisions in Energetic Reactions. This method includes the effect of Bose correlations for the emitted pion pair. Effects arising from correlations between space-time and momentum space distributions are investigated. The results are compared to the data of two different experiments. The role and interpretation of the chaocity parameter are discussed. (D.G.) 14 refs.; 4 figs

  4. Spacers for fuel rod clusters

    International Nuclear Information System (INIS)

    Jabsen, F.S.

    1978-01-01

    The proposition deals with the fixing of nuclear fuel element rods in a grid which consists of a number of crossed Zy-plates which form cells. The rectangular cells have projections which serve as spacers for the fuel rods. According to the invention there are additional butt straps which can be moved in such a way that insertion and extraction of the fuel rods can be done without obstruction and they can be spring-loaded hold in their final position. (UWI) [de

  5. Genotypic Characterization of Bradyrhizobium Strains Nodulating Endemic Woody Legumes of the Canary Islands by PCR-Restriction Fragment Length Polymorphism Analysis of Genes Encoding 16S rRNA (16S rDNA) and 16S-23S rDNA Intergenic Spacers, Repetitive Extragenic Palindromic PCR Genomic Fingerprinting, and Partial 16S rDNA Sequencing

    Science.gov (United States)

    Vinuesa, Pablo; Rademaker, Jan L. W.; de Bruijn, Frans J.; Werner, Dietrich

    1998-01-01

    We present a phylogenetic analysis of nine strains of symbiotic nitrogen-fixing bacteria isolated from nodules of tagasaste (Chamaecytisus proliferus) and other endemic woody legumes of the Canary Islands, Spain. These and several reference strains were characterized genotypically at different levels of taxonomic resolution by computer-assisted analysis of 16S ribosomal DNA (rDNA) PCR-restriction fragment length polymorphisms (PCR-RFLPs), 16S-23S rDNA intergenic spacer (IGS) RFLPs, and repetitive extragenic palindromic PCR (rep-PCR) genomic fingerprints with BOX, ERIC, and REP primers. Cluster analysis of 16S rDNA restriction patterns with four tetrameric endonucleases grouped the Canarian isolates with the two reference strains, Bradyrhizobium japonicum USDA 110spc4 and Bradyrhizobium sp. strain (Centrosema) CIAT 3101, resolving three genotypes within these bradyrhizobia. In the analysis of IGS RFLPs with three enzymes, six groups were found, whereas rep-PCR fingerprinting revealed an even greater genotypic diversity, with only two of the Canarian strains having similar fingerprints. Furthermore, we show that IGS RFLPs and even very dissimilar rep-PCR fingerprints can be clustered into phylogenetically sound groupings by combining them with 16S rDNA RFLPs in computer-assisted cluster analysis of electrophoretic patterns. The DNA sequence analysis of a highly variable 264-bp segment of the 16S rRNA genes of these strains was found to be consistent with the fingerprint-based classification. Three different DNA sequences were obtained, one of which was not previously described, and all belonged to the B. japonicum/Rhodopseudomonas rDNA cluster. Nodulation assays revealed that none of the Canarian isolates nodulated Glycine max or Leucaena leucocephala, but all nodulated Acacia pendula, C. proliferus, Macroptilium atropurpureum, and Vigna unguiculata. PMID:9603820

  6. Enterococcus faecalis Responds to Individual Exogenous Fatty Acids Independently of Their Degree of Saturation or Chain Length.

    Science.gov (United States)

    Saito, Holly E; Harp, John R; Fozo, Elizabeth M

    2018-01-01

    Enterococcus faecalis is a commensal of the human gastrointestinal tract that can persist in the external environment and is a leading cause of hospital-acquired infections. Given its diverse habitats, the organism has developed numerous strategies to survive a multitude of environmental conditions. Previous studies have demonstrated that E. faecalis will incorporate fatty acids from bile and serum into its membrane, resulting in an induced tolerance to membrane-damaging agents. To discern whether all fatty acids induce membrane stress protection, we examined how E. faecalis responded to individually supplied fatty acids. E. faecalis readily incorporated fatty acids 14 to 18 carbons in length into its membrane but poorly incorporated fatty acids shorter or longer than this length. Supplementation with saturated fatty acids tended to increase generation time and lead to altered cellular morphology in most cases. Further, exogenously supplied saturated fatty acids did not induce tolerance to the membrane-damaging antibiotic daptomycin. Supplementation with unsaturated fatty acids produced variable growth effects, with some impacting generation time and morphology. Exogenously supplied unsaturated fatty acids that are normally produced by E. faecalis and those that are found in bile or serum could restore growth in the presence of a fatty acid biosynthetic inhibitor. However, only the eukaryote-derived fatty acids oleic acid and linoleic acid provided protection from daptomycin. Thus, exogenous fatty acids do not lead to a common physiological effect on E. faecalis The organism responds uniquely to each, and only host-derived fatty acids induce membrane protection. IMPORTANCE Enterococcus faecalis is a commonly acquired hospital infectious agent with resistance to many antibiotics, including those that target its cellular membrane. We previously demonstrated that E. faecalis will incorporate fatty acids found in human fluids, like serum, into its cellular membrane

  7. Production of medium-chain-length polyhydroxyalkanoate by Pseudomonas oleovorans grown in sugary cassava extract supplemented with andiroba oil

    Directory of Open Access Journals (Sweden)

    Diego Aires da Silva

    2014-12-01

    Full Text Available Pseudomonas oleovorans were grown on sugary cassava extracts supplemented with andiroba oil for the synthesis of a mediumchain- length polyhydroxyalkanoate (PHA MCL. The concentration of total sugars in the extract was approximately: 40 g/L in culture 1, 15 g/L in cultures 2 and 3, and 10 g/L in culture 4. Supplementation with 1% andiroba oil and 0.2 g/L of (NH42HPO4 was performed 6.5 hours after growth in culture 3, and supplementation with the same amount of andiroba oil and 2.4 g/L of (NH42HPO4 was performed at the beginning of growth in culture 4. The synthesis resulted mainly in 3-hydroxy-decanoate and 3-hydroxy-dodecanoate units; 3-hydroxy-butyrate, 3-hydroxy-hexanoate; and 3-hydroxy-octanoate monomers were also produced but in smaller proportions. P. oleovorans significantly accumulated PHA MCL in the deceleration phase of growth with an oxygen limitation but with sufficient nitrogen concentration to maintain cell growth. The sugary cassava extract supplemented with andiroba oil proved to be a potential substrate for PHA MCL production.

  8. Development of a High Performance Spacer Grid

    Energy Technology Data Exchange (ETDEWEB)

    Song, Kee Nam; Song, K. N.; Yoon, K. H. (and others)

    2007-03-15

    A spacer grid in a LWR fuel assembly is a key structural component to support fuel rods and to enhance the heat transfer from the fuel rod to the coolant. In this research, the main research items are the development of inherent and high performance spacer grid shapes, the establishment of mechanical/structural analysis and test technology, and the set-up of basic test facilities for the spacer grid. The main research areas and results are as follows. 1. 18 different spacer grid candidates have been invented and applied for domestic and US patents. Among the candidates 16 are chosen from the patent. 2. Two kinds of spacer grids are finally selected for the advanced LWR fuel after detailed performance tests on the candidates and commercial spacer grids from a mechanical/structural point of view. According to the test results the features of the selected spacer grids are better than those of the commercial spacer grids. 3. Four kinds of basic test facilities are set up and the relevant test technologies are established. 4. Mechanical/structural analysis models and technology for spacer grid performance are developed and the analysis results are compared with the test results to enhance the reliability of the models.

  9. How to use an inhaler - no spacer

    Science.gov (United States)

    ... MDI) administration - no spacer; Bronchial nebulizer; Wheezing - nebulizer; Reactive airway - nebulizer; COPD - ... 66. National Asthma Education and Prevention Program website. How to use a metered-dose inhaler. ...

  10. Optimization of Water/Oil/Surfactant System for Preparation of Medium-Chain-Length Poly-3-Hydroxyalkanoates (mcl-PHA)-Incorporated Nanoparticles via Nanoemulsion Templating Technique.

    Science.gov (United States)

    Ishak, K A; Annuar, M Suffian M; Ahmad, N

    2017-12-01

    Polymeric nanoparticles gain a widespread interest in food and pharmaceutical industries as delivery systems that encapsulate, protect, and release lipophilic compounds such as omega-3 fatty acids, fat-soluble vitamins, carotenoids, carvedilol, cyclosporine, and ketoprofen. In this study, medium-chain-length poly-3-hydroxyalkanoate (mcl-PHA)-incorporated nanoparticle was developed via facile organic solvent-free nanoemulsion templating technique. The water content (W/surfactant-to-oil (S/O)), S/O, and Cremophor EL-to-Span 80 (Cremo/Sp80) ratios were first optimized using response surface methodology (RSM) to obtain nanoemulsion template prior to incorporation of mcl-PHA. Their effects on nanoemulsion formation were investigated. The mcl-PHA-incorporated nanoparticle system showed a good preservation capability of β-carotene and extended storage stability.

  11. Dependency of Anion and Chain Length of Imidazolium Based Ionic Liquid on Micellization of the Block Copolymer F127 in Aqueous Solution: An Experimental Deep Insight

    Directory of Open Access Journals (Sweden)

    Jignesh Lunagariya

    2017-07-01

    Full Text Available The non-ionic triblock copolymer, Pluronic® F127, has been selected to observe its interaction with ionic liquids (ILs in aqueous solutions by using DLS, surface tension, and viscosity measurements. The Critical Micelle Concentration (CMC of F127 increased with the addition of ILs, which appeared logical since it increases the solubility of PPO (and PEO moiety, making it behaves more like a hydrophilic block copolymer that is micellized at a higher copolymer concentration. The results from DLS data showed good agreement with those obtained from the surface tension measurements. Upon the addition of ILs, the tendency in micellar size reduction was demonstrated by viscosity results, and therefore, intrinsic viscosity decreased compared to pure F127 in aqueous solution. The results were discussed as a function of alkyl chain length and anions of imidazolium based ILs.

  12. Effects of PEG tethering chain length of vitamin E TPGS with a Herceptin-functionalized nanoparticle formulation for targeted delivery of anticancer drugs.

    Science.gov (United States)

    Zhao, Jing; Feng, Si-Shen

    2014-03-01

    Drug formulation by ligand conjugated nanoparticles of biodegradable polymers has become one of the most important strategies in drug targeting. We have developed in our previous work nanoparticles of a mixture of two vitamin E TPGS based copolymers PLA-TPGS and TPGS-TOOH with the latter for Herceptin conjugation for targeted delivery of anticancer drugs such as docetaxel to the cancer cells of human epidermal growth factor receptor 2 (HER2) overexpression. In this research, we investigated the effects of the PEG chain length in TPGS, which is in fact a PEGylated vitamin E, on the cellular uptake and cytotoxicity of the drug formulated in the Herceptin-conjugated nanoparticles of PLA-TPGS/TPGS-COOH blend (NPs). Such NPs of PEG1000, PEG2000, PEG3350 and PEG5000, i.e. the PEG of molecule weight 1000, 2000, 3350 and 5000, were prepared by the nanoprecipitation method and characterized for their size and size distribution, drug loading, surface morphology, surface charge and surface chemistry as well as in vitro drug release profile, cellular uptake and cytotoxicity. We found among such nanoparticles, those of PEG1000, i.e. of the shortest PEG tethering chain length, could result in the best therapeutic effects, which are 24.1%, 37.3%, 38.1% more efficient in cellular uptake and 68.1%, 90%, 92.6% lower in IC50 (thus higher in cytotoxicity) than the Herceptin-conjugated nanoparticles of PLA-TPGS/TPGS-COOH blend of PEG2000, PEG3350 and PEG5000 respectively in treatment of SK-BR-3 cancer cells which are of high HER2 overexpression. We provided a theoretical explanation from surface mechanics and thermodynamics for endocytosis of nanoparticles. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Crystal structure of heterodimeric hexaprenyl diphosphate synthase from Micrococcus luteus B-P 26 reveals that the small subunit is directly involved in the product chain length regulation.

    Science.gov (United States)

    Sasaki, Daisuke; Fujihashi, Masahiro; Okuyama, Naomi; Kobayashi, Yukiko; Noike, Motoyoshi; Koyama, Tanetoshi; Miki, Kunio

    2011-02-04

    Hexaprenyl diphosphate synthase from Micrococcus luteus B-P 26 (Ml-HexPPs) is a heterooligomeric type trans-prenyltransferase catalyzing consecutive head-to-tail condensations of three molecules of isopentenyl diphosphates (C(5)) on a farnesyl diphosphate (FPP; C(15)) to form an (all-E) hexaprenyl diphosphate (HexPP; C(30)). Ml-HexPPs is known to function as a heterodimer of two different subunits, small and large subunits called HexA and HexB, respectively. Compared with homooligomeric trans-prenyltransferases, the molecular mechanism of heterooligomeric trans-prenyltransferases is not yet clearly understood, particularly with respect to the role of the small subunits lacking the catalytic motifs conserved in most known trans-prenyltransferases. We have determined the crystal structure of Ml-HexPPs both in the substrate-free form and in complex with 7,11-dimethyl-2,6,10-dodecatrien-1-yl diphosphate ammonium salt (3-DesMe-FPP), an analog of FPP. The structure of HexB is composed of mostly antiparallel α-helices joined by connecting loops. Two aspartate-rich motifs (designated the first and second aspartate-rich motifs) and the other characteristic motifs in HexB are located around the diphosphate part of 3-DesMe-FPP. Despite the very low amino acid sequence identity and the distinct polypeptide chain lengths between HexA and HexB, the structure of HexA is quite similar to that of HexB. The aliphatic tail of 3-DesMe-FPP is accommodated in a large hydrophobic cleft starting from HexB and penetrating to the inside of HexA. These structural features suggest that HexB catalyzes the condensation reactions and that HexA is directly involved in the product chain length control in cooperation with HexB.

  14. Allelic sequence variations in the hypervariable region of a T-cell receptor β chain: Correlation with restriction fragment length polymorphism in human families and populations

    International Nuclear Information System (INIS)

    Robinson, M.A.

    1989-01-01

    Direct sequence analysis of the human T-cell antigen receptor (TCR) V β1 variable gene identified a single base-pair allelic variation (C/G) located within the coding region. This change results in substitution of a histidine (CAC) for a glutamine (CAG) at position 48 of the TCR β chain, a position predicted to be in the TCR antigen binding site. The V β1 polymorphism was found by DNA sequence analysis of V β1 genes from seven unrelated individuals; V β1 genes were amplified by the polymerase chain reaction, the amplified fragments were cloned into M13 phage vectors, and sequences were determined. To determined the inheritance patterns of the V β1 substitution and to test correlation with V β1 restriction fragment length polymorphism detected with Pvu II and Taq I, allele-specific oligonucleotides were constructed and used to characterize amplified DNA samples. Seventy unrelated individuals and six families were tested for both restriction fragment length polymorphism and for the V β1 substitution. The correlation was also tested using amplified, size-selected, Pvu II- and Taq I-digested DNA samples from heterozygotes. Pvu II allele 1 (61/70) and Taq I allele 1 (66/70) were found to be correlated with the substitution giving rise to a histidine at position 48. Because there are exceptions to the correlation, the use of specific probes to characterize allelic forms of TCR variable genes will provide important tools for studies of basic TCR genetics and disease associations

  15. Computer-Aided Design Method of Warp-Knitted Jacquard Spacer Fabrics

    Directory of Open Access Journals (Sweden)

    Li Xinxin

    2016-06-01

    Full Text Available Based on a further study on knitting and jacquard principles, this paper presents a mathematical design model to make computer-aided design of warp-knitted jacquard spacer fabrics more efficient. The mathematical model with matrix method employs three essential elements of chain notation, threading and Jacquard designing. With this model, the processing to design warp-knitted jacquard spacer fabrics with CAD software is also introduced. In this study, the sports shoes which have separated functional areas according to the feet structure and characteristics of movement are analysed. The results show the different patterns on Jacquard spacer fabrics that are seamlessly stitched with jacquard technics. The computer-aided design method of warp-knitted jacquard spacer fabrics is efficient and simple.

  16. Micelle formation of nonionic surfactants in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate: surfactant chain length dependence of the critical micelle concentration.

    Science.gov (United States)

    Inoue, Tohru; Yamakawa, Haruka

    2011-04-15

    Micellization behavior was investigated for polyoxyethylene-type nonionic surfactants with varying chain length (C(n)E(m)) in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF(4)). Critical micelle concentration (cmc) was determined from the variation of (1)H NMR chemical shift with the surfactant concentration. The logarithmic value of cmc decreased linearly with the number of carbon atoms in the surfactant hydrocarbon chain, similarly to the case observed in aqueous surfactant solutions. However, the slope of the straight line is much smaller in bmimBF(4) than in aqueous solution. Thermodynamic parameters for micelle formation estimated from the temperature dependence of cmc showed that the micellization in bmimBF(4) is an entropy-driven process around room temperature. This behavior is also similar to the case in aqueous solution. However, the magnitude of the entropic contribution to the overall micellization free energy in bmimBF(4) is much smaller compared with that in aqueous solution. These results suggest that the micellization in bmimBF(4) proceeds through a mechanism similar to the hydrophobic interaction in aqueous surfactant solutions, although the solvophobic effect in bmimBF(4) is much weaker than the hydrophobic effect. Copyright © 2011 Elsevier Inc. All rights reserved.

  17. Density functional theory study of silodithiophene thiophenepyrrolopyrroledion-based small molecules: The effect of alkyl side chain length in electron donor materials

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Dong Kyun; Yeo, Hak; Kwak, Kyung Won [Dept. of Chemistry, Chung-Ang University, Seoul (Korea, Republic of); Yoon, Young Woon; Kim, Bong Soo [Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology, Seoul (Korea, Republic of); Lee, Kyung Koo [Dept. of Chemistry, Kunsan National University, Gunsan (Korea, Republic of)

    2015-02-15

    Push–pull small molecules are promising electron-donor materials for organic solar cells. Thus, precise prediction of their electronic structures is of paramount importance to control the optical and electrical properties of the solar cells. Various types of alkyl chains are usually introduced to increase solubility and modify the morphology of the resulting molecular films. Here, using density functional theory (DFT) and time-dependent DFT (TD-DFT), we report the precise effect of increasing the length of the alkyl chain on the electronic structure of an electron donor molecule 6,60-((4,4-dialkyl-4H-silolo[3,2-b:4,5-b′]-dithiophene-2,6-diyl) bis(thiophene-5,2-diyl))bis(2,5-alkyl-3-(thiophen-2-yl) -2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione) (DTS1TDPP). Alkyl groups were attached to the bridging position (silicon atom) of the fused rings and nitrogen atom of the pyrrolopyrroledione groups. We demonstrate that the alkyl groups do not perturb the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels, π-delocalized backbone structure, and UV–Vis absorption spectrum when they are placed at the least steric effect positions.

  18. Roles of head group architecture and side chain length on colorimetric response of polydiacetylene vesicles to temperature, ethanol and pH.

    Science.gov (United States)

    Charoenthai, Nipaphat; Pattanatornchai, Thanutpon; Wacharasindhu, Sumrit; Sukwattanasinitt, Mongkol; Traiphol, Rakchart

    2011-08-15

    In this contribution, we report the relationship between molecular structures of polydiacetylene (PDA) vesicles, fabricated by using three monomers, 10,12-tricosadiynoic acid (TCDA), 10,12-pentacosadiynoic acid (PCDA) and N-(2-aminoethyl)pentacosa-10,12-diynamide (AEPCDA), and their color-transition behaviors. The modification of side chain length and head group of the PDA vesicles strongly affects the colorimetric response to temperature, ethanol and pH. A shorter side chain of poly(TCDA) yields weaker inter- and intra-chain dispersion interactions in the bilayers compared to the system of poly(PCDA), which in turn results in a faster color transition upon exposure to all stimuli. A change of head group in poly(AEPCDA) slightly reduces the transition temperature. Interestingly, the colorimetric response of poly(AEPCDA) vesicles to the addition of ethanol is found to occur in a two-step fashion while the response of poly(PCDA) vesicles takes place in a one-step process. The amount of ethanol required for inducing complete color-transition of poly(AEPCDA) vesicles is also much higher, about 87% v/v. The increase of pH to ~9 and ~10 causes a color-transition of poly(TCDA) and poly(PCDA) vesicles, respectively. The poly(AEPCDA) vesicles, on the other hand, change color upon decreasing pH to ~0. The colorimetric response also occurs in a multi-step fashion. These discrepancies are attributed to the architecture of surface layers of poly(AEPCDA), constituting amine and amide groups separated by ethyl linkers. Copyright © 2011 Elsevier Inc. All rights reserved.

  19. Thermosensitive mPEG-b-PA-g-PNIPAM comb block copolymer micelles: effect of hydrophilic chain length and camptothecin release behavior.

    Science.gov (United States)

    Yang, Xiao-Li; Luo, Yan-Ling; Xu, Feng; Chen, Ya-Shao

    2014-02-01

    Block copolymer micelles are extensively used as drug controlled release carriers, showing promising application prospects. The comb or brush copolymers are especially of great interest, whose densely-grafted side chains may be important for tuning the physicochemical properties and conformation in selective solvents, even in vitro drug release. The purpose of this work was to synthesize novel block copolymer combs via atom transfer radical polymerization, to evaluate its physicochemical features in solution, to improve drug release behavior and to enhance the bioavailablity, and to decrease cytotoxicity. The physicochemical properties of the copolymer micelles were examined by modulating the composition and the molecular weights of the building blocks. A dialysis method was used to load hydrophobic camptothecin (CPT), and the CPT release and stability were detected by UV-vis spectroscopy and high-performance liquid chromatography, and the cytotoxicity was evaluated by MTT assays. The copolymers could self-assemble into well-defined spherical core-shell micelle aggregates in aqueous solution, and showed thermo-induced micellization behavior, and the critical micelle concentration was 2.96-27.64 mg L(-1). The micelles were narrow-size-distribution, with hydrodynamic diameters about 128-193 nm, depending on the chain length of methoxy polyethylene glycol (mPEG) blocks and poly(N-isopropylacrylamide) (PNIPAM) graft chains or/and compositional ratios of mPEG to PNIPAM. The copolymer micelles could stably and effectively load CPT but avoid toxicity and side-effects, and exhibited thermo-dependent controlled and targeted drug release behavior. The copolymer micelles were safe, stable and effective, and could potentially be employed as CPT controlled release carriers.

  20. Genotyping of major histocompatibility complex Class II DRB gene in Rohilkhandi goats by polymerase chain reaction-restriction fragment length polymorphism and DNA sequencing

    Directory of Open Access Journals (Sweden)

    Kush Shrivastava

    2015-10-01

    Full Text Available Aim: To study the major histocompatibility complex (MHC Class II DRB1 gene polymorphism in Rohilkhandi goat using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP and nucleotide sequencing techniques. Materials and Methods: DNA was isolated from 127 Rohilkhandi goats maintained at sheep and goat farm, Indian Veterinary Research Institute, Izatnagar, Bareilly. A 284 bp fragment of exon 2 of DRB1 gene was amplified and digested using BsaI and TaqI restriction enzymes. Population genetic parameters were calculated using Popgene v 1.32 and SAS 9.0. The genotypes were then sequenced using Sanger dideoxy chain termination method and were compared with related breeds/species using MEGA 6.0 and Megalign (DNASTAR software. Results: TaqI locus showed three and BsaI locus showed two genotypes. Both the loci were found to be in Hardy–Weinberg equilibrium (HWE, however, population genetic parameters suggest that heterozygosity is still maintained in the population at both loci. Percent diversity and divergence matrix, as well as phylogenetic analysis revealed that the MHC Class II DRB1 gene of Rohilkhandi goats was found to be in close cluster with Garole and Scottish blackface sheep breeds as compared to other goat breeds included in the sequence comparison. Conclusion: The PCR-RFLP patterns showed population to be in HWE and absence of one genotype at one locus (BsaI, both the loci showed excess of one or the other homozygote genotype, however, effective number of alleles showed that allelic diversity is present in the population. Sequence comparison of DRB1 gene of Rohilkhandi goat with other sheep and goat breed assigned Rohilkhandi goat in divergence with Jamanupari and Angora goats.

  1. Chain-Length Distribution and Hydrogen Isotopic Fraction of n-alkyl Lipids in Aquatic and Terrestrial Plants: Implications for Paleoclimate Reconstructions

    Science.gov (United States)

    Gao, L.; Littlejohn, S.; Hou, J.; Toney, J.; Huang, Y.

    2008-12-01

    Recent studies demonstrate that in lacustrine sediments, aquatic plant lipids (e.g., C22-fatty acid) record lake water D/H ratio variation, while long-chain fatty acids (C26-C32, major components of terrestrial plant leaf waxes), record D/H ratios of precipitation (especially in arid regions). However, there are insufficient literature data for the distribution and hydrogen isotopic fractionation of n-alkyl lipids in aquatic and terrestrial plants. In this study, we determined the chain-length distributions and D/H ratios of n-alkyl lipids from 17 aquatic plant species (9 emergent, 4 floating and 4 submerge species) and 13 terrestrial plant species (7 grasses and 6 trees) from Blood Pond, Massachusetts. Our results are consistent with previous studies and provide a solid basis for the paleoclimatic reconstruction using D/H ratios of aquatic and terrestrial plant biomarkers. In addition, systematic hydrogen isotopic analyses on leaf waxes, leaf, stem and soil waters from trees and grasses significantly advance our understanding of our previously observed large D/H ratio difference between tree and grass leaf waxes. Our data indicate that the observed difference is not due to differences in leaf water D/H ratios. In comparison with grasses, trees use greater proportion of D-enriched residual or stored carbohydrates (as opposed to current photosynthetic carbohydrates) for leaf wax biosynthesis, resulting in higher leaf wax D/H ratios. The residual carbohydrates are enriched in deuterium because of the preferential consumption of light-hydrogen substrates during plant metabolism.

  2. Asymmetric Conjugated Molecules Based on [1]Benzothieno[3,2-b][1]benzothiophene for High-Mobility Organic Thin-Film Transistors: Influence of Alkyl Chain Length.

    Science.gov (United States)

    He, Keqiang; Li, Weili; Tian, Hongkun; Zhang, Jidong; Yan, Donghang; Geng, Yanhou; Wang, Fosong

    2017-10-11

    Herein, we report the synthesis and characterization of a series of [1]benzothieno[3,2-b][1]benzothiophene (BTBT)-based asymmetric conjugated molecules, that is, 2-(5-alkylthiophen-2-yl)[1]benzothieno[3,2-b][1]benzothiophene (BTBT-Tn, in which T and n represent thiophene and the number of carbons in the alkyl group, respectively). All of the molecules with n ≥ 4 show mesomorphism and display smectic A, smectic B (n = 4), or smectic E (n > 4) phases and then crystalline phases in succession upon cooling from the isotropic state. Alkyl chain length has a noticeable influence on the microstructures of vacuum-deposited films and therefore on the performance of the organic thin-film transistors (OTFTs). All molecules except for 2-(thiophen-2-yl)[1]benzothieno[3,2-b][1]benzothiophene and 2-(5-ethylthiophen-2-yl)[1]benzothieno[3,2-b][1]benzothiophene showed OTFT mobilities above 5 cm 2 V -1 s -1 . 2-(5-Hexylthiophen-2-yl)[1]benzothieno[3,2-b][1]benzothiophene and 2-(5-heptylthiophen-2-yl)[1]benzothieno[3,2-b][1]benzothiophene showed the greatest OTFT performance with reliable hole mobilities (μ) up to 10.5 cm 2 V -1 s -1 because they formed highly ordered and homogeneous films with diminished grain boundaries.

  3. Synthetic high-charge organomica: effect of the layer charge and alkyl chain length on the structure of the adsorbed surfactants.

    Science.gov (United States)

    Pazos, M Carolina; Castro, Miguel A; Orta, M Mar; Pavón, Esperanza; Valencia Rios, Jesús S; Alba, María D

    2012-05-15

    A family of organomicas was synthesized using synthetic swelling micas with high layer charge (Na(n)Si(8-n)Al(n)Mg(6)F(4)O(20)·XH(2)O, where n = 2, 3, and 4) exchanged with dodecylammonium and octadecylammonium cations. The molecular arrangement of the surfactant was elucidated on the basis on XRD patterns and DTA. The ordering conformation of the surfactant molecules into the interlayer space of micas was investigated by (13)C, (27)Al, and (29)Si MAS NMR. The arrangement of alkylammonium ions in these high-charge synthetic micas depends on the combined effects of the layer charge of the mica and the chain length of the cation. In the organomicas with dodecylammonium, a transition from a parallel layer to a bilayer-paraffin arrangement is observed when the layer charge of the mica increases. However, when octadecylammonium is the interlayer cation, the molecular arrangement of the surfactant was found to follow the bilayer-paraffin model for all values of layer charge. The amount of ordered conformation all-trans is directly proportional of layer charge.

  4. Identification of Pork Contamination in Meatballs of Indonesia Local Market Using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP Analysis

    Directory of Open Access Journals (Sweden)

    Yuny Erwanto

    2014-10-01

    Full Text Available This research applied and evaluated a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP using cytochrome b gene to detect pork contamination in meatballs from local markets in Surabaya and Yogyakarta regions, Indonesia. To confirm the effectiveness and specificity of this fragment, thirty nine DNA samples from different meatball shops were isolated and amplified, and then the PCR amplicon was digested by BseDI restriction enzyme to detect the presence of pork in meatballs. BseDI restriction enzyme was able to cleave porcine cytochrome b gene into two fragments (131 bp and 228 bp. Testing the meatballs from the local market showed that nine of twenty meatball shops in Yogyakarta region were detected to have pork contamination, but there was no pork contamination in meatball shops in Surabaya region. In conclusion, specific PCR amplification of cytochrome b gen and cleaved by BseDI restriction enzymes seems to be a powerful technique for the identification of pork presence in meatball because of its simplicity, specificity and sensitivity. Furthermore, pork contamination intended for commercial products of sausage, nugget, steak and meat burger can be checked. The procedure is also much cheaper than other methods based on PCR, immunodiffusion and other techniques that need expensive equipment.

  5. Identification of Pork Contamination in Meatballs of Indonesia Local Market Using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) Analysis.

    Science.gov (United States)

    Erwanto, Yuny; Abidin, Mohammad Zainal; Sugiyono, Eko Yasin Prasetyo Muslim; Rohman, Abdul

    2014-10-01

    This research applied and evaluated a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) using cytochrome b gene to detect pork contamination in meatballs from local markets in Surabaya and Yogyakarta regions, Indonesia. To confirm the effectiveness and specificity of this fragment, thirty nine DNA samples from different meatball shops were isolated and amplified, and then the PCR amplicon was digested by BseDI restriction enzyme to detect the presence of pork in meatballs. BseDI restriction enzyme was able to cleave porcine cytochrome b gene into two fragments (131 bp and 228 bp). Testing the meatballs from the local market showed that nine of twenty meatball shops in Yogyakarta region were detected to have pork contamination, but there was no pork contamination in meatball shops in Surabaya region. In conclusion, specific PCR amplification of cytochrome b gen and cleaved by BseDI restriction enzymes seems to be a powerful technique for the identification of pork presence in meatball because of its simplicity, specificity and sensitivity. Furthermore, pork contamination intended for commercial products of sausage, nugget, steak and meat burger can be checked. The procedure is also much cheaper than other methods based on PCR, immunodiffusion and other techniques that need expensive equipment.

  6. Production of Medium-Chain-Length Poly(3-Hydroxyalkanoates from Saponified Palm Kernel Oil by Pseudomonas putida: Kinetics of Batch and Fed-Batch Fermentations

    Directory of Open Access Journals (Sweden)

    Annuar, M. S. M.

    2006-01-01

    Full Text Available The kinetics of medium-chain-length poly(3-hydroxyalkanoates, PHAMCL production by Pseudomonas putida PGA1 in batch and fed-batch fermentations were studied. With saponified palm kernel oil (SPKO supplying the free fatty acids mixture as the sole carbon and energy source, PHAMCL accumulation is encouraged under ammonium-limited condition, which is a nitrogen stress environment. The amount of PHAMCL accumulated and its specific production rate, qPHA were influenced by the residual ammonium concentration level in the culture medium. It was observed that in both fermentation modes, when the residual ammonium was exhausted (< 0.05 gL-1, the PHAMCL accumulation (11.9% and qPHA (0.0062 h-1 were significantly reduced. However, this effect can be reversed by feeding low amount of ammonium to the culture, resulting in significantly improved PHAMCL yield (71.4% and specific productivity (0.6 h-1. It is concluded that the feeding of low ammonium concentration to the culture medium during the PHAMCL accumulation has a positive effect on sustaining the PHAMCL biosynthetic capability of the organism. It was also found that increasing SPKO concentration in the medium significantly reduced (up to 50% the volumetric oxygen transfer coefficient (KLa of the fermentation system.

  7. The color tuning of PS-b-P2VP lamellar films with changing the alkyl chain length of 1-iodoalkanes.

    Science.gov (United States)

    Shin, Sung-Eui; Kim, Su-Young; Shin, Dong-Myung

    2011-05-01

    Photonic crystals with tunability in the visible or near-infrared region have drawn increasing attention for controlling and processing light for the active components of future display. We prepared polystyrene-b-poly(2-vinyl pyridine) (PS-b-P2VP) lamellar films which is hydrophobic block-hydrophilic polyelectrolyte block polymer of 57 kg/mol-b-57 kg/mol. The lamellar stacks, which is alternating layer of hydrophilic and hydrophobic moiety of PS-b-P2VP, are obtained by exposing the spin coated film under chloroform vapor. The band gaps of the lamellar films interestingly varied after immersion into the quaternizing solvents containing 5 wt% of iodomethane, iodoethane, 1-iodobutane, 1-iodopentane, 1-iodohexane and 1-iodooctane solubilized in n-hexane. The iodoalkanes reacted with pyridine groups in PS-b-P2VP and generated the alkyl pyridinium salts readily. The degree of quaternization, alkyl chain length of iodoalkane and the salt water concentration affects the spacing of layer structure of PS-b-P2VP. The iodomethane and iodohexane produced similar band gaps and salt concentration dependence. These results are very much dependent on the hydrophobic-hydrophilic characters of PS-b-P2VP lamellar surface.

  8. The prevalence of cryptosporidiosis in Turkish children, and geno typing of isolates by nested polymerase chain reaction-restriction fragment length polymorphism

    International Nuclear Information System (INIS)

    Tamer, Gulden S.; Turk, M.; Dagci, H.; Pektas, B.; Guruz, Adnan Y.; Uner, A.; Guy, E.C.

    2007-01-01

    Objective was to verify the incidence of cryptosporidiosis among Turkish elementary school students. The study was conducted in the Dept. of Parasitology, Faculty of Medicine, Ege University, Turkey during a 3-month period in 2006. We assessed the fecal samples of 707 children using modified acid-fast and phenol-auramine staining followed by modified Ritchie concentration method. All cryptosporidium species isolates were analysed by nested polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) to differentiate genotypes of the isolates. After the coprological examination, 4 samples were found to be positive for cryptosporidium species oocysts. In the present study, all 4 oocysts were of zoonotic origin and belonged to cryptoporodium parvum genotype 2 indicating that in Turkey the potential sources of human cryptosporidiosis is from animals. The application of genotyping to clinical isolates of cryptosporidium has significantly increased our knowledge and understanding of the distribution and epidemiology of this parasite. The PCR and RFLP techniques represent a more rapid and simple method of genotyping to support epidemiological and clinical investigations than conventional analytical DNA techniques. (author)

  9. Quinoidal Oligo(9,10-anthryl)s with Chain-Length-Dependent Ground States: A Balance between Aromatic Stabilization and Steric Strain Release

    KAUST Repository

    Lim, Zhenglong

    2015-11-12

    Quinoidal π-conjugated polycyclic hydrocarbons have attracted intensive research interest due to their unique optical/electronic properties and possible magnetic activity, which arises from a thermally excited triplet state. However, there is still lack of fundamental understanding on the factors that determine the electronic ground states. Herein, by using quinoidal oligo(9,10-anthryl)s, it is demonstrated that both aromatic stabilisation and steric strain release play balanced roles in determining the ground states. Oligomers with up to four anthryl units were synthesised and their ground states were investigated by electronic absorption and electron spin resonance (ESR) spectroscopy, assisted by density functional theory (DFT) calculations. The quinoidal 9,10-anthryl dimer 1 has a closed-shell ground state, whereas the tri- (2) and tetramers (3) both have an open-shell diradical ground state with a small singlet-triplet gap. Such a difference results from competition between two driving forces: the large steric repulsion between the anthryl/phenyl units in the closed-shell quinoidal form that drives the molecule to a flexible open-shell diradical structure, and aromatic stabilisation due to the gain of more aromatic sextet rings in the closed-shell form, which drives the molecule towards a contorted quinoidal structure. The ground states of these oligomers thus depend on the overall balance between these two driving forces and show chain-length dependence. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. The normal chain length distribution of the O antigen is required for the interaction of Shigella flexneri 2a with polarized Caco-2 cells

    Directory of Open Access Journals (Sweden)

    Anilei Hoare

    2012-01-01

    Full Text Available Shigella flexneri causes bacillary dysentery in humans. Essential to the establishment of the disease is the invasion of the colonic epithelial cells. Here we investigated the role of the lipopolysaccharide (LPS O antigen in the ability of S. flexneri to adhere to and invade polarized Caco-2 cells. The S. flexneri 2a O antigen has two preferred chain lengths: a short O antigen (S-OAg regulated by the WzzB protein and a very long O antigen (VL-OAg regulated by Wzz pHS2. Mutants with defined deletions of the genes required for O-antigen assembly and polymerization were constructed and assayed for their abilities to adhere to and enter cultured epithelial cells. The results show that both VL- and S-OAg are required for invasion through the basolateral cell membrane. In contrast, the absence of O antigen does not impair adhesion. Purified LPS does not act as a competitor for the invasion of Caco-2 cells by the wild-type strain, suggesting that LPS is not directly involved in the internalization process by epithelial cells.

  11. Diffusional behavior of n-paraffins with various chain lengths in urea adduct channels by pulsed field-gradient spin-echo NMR spectroscopy

    International Nuclear Information System (INIS)

    Kim, Sunmi; Kuroki, Shigeki; Ando, Isao

    2006-01-01

    The diffusion coefficients (D) of n-paraffin molecules (n-C n H 2n+2 ) with various chain-lengths (n = 8, 12, 21, 26, 28 and 32) in the long channels of a deuterated urea-d 4 adduct have been measured at 25 deg. C by means of pulsed field-gradient spin-echo 1 H NMR method. The aim is to clarify diffusional behavior of the n-paraffin molecules in the urea adduct channels. From the experimental results, it is found that n-paraffin molecules are diffusing in the long channels and have two kinds of diffusion components, namely a fast (D ∼ 10 -10 m 2 /s) and a slow diffusion component (D ∼ 10 -11 m 2 /s). The diffusing-time (Δ) dependence of the diffusion coefficients of the n-paraffins shows some likely evidence of restricted diffusion since the n-paraffin molecules are confined in the urea channel. The diffusion coefficients (D) decrease as the carbon number increases from 8 to 28, and very slowly decreases as the carbon number increases from 28 to 32

  12. Simultaneous and rapid differential diagnosis of Mycoplasma genitalium and Ureaplasma urealyticum based on a polymerase chain reaction-restriction fragment length polymorphism

    Directory of Open Access Journals (Sweden)

    R Mirnejad

    2011-01-01

    Full Text Available Objectives: The aim of this investigation was to simultaneously detect and differentiate Mycoplasma genitalium and Ureaplasma urealyticum in female patients suffering from genital complications by polymerase chain reaction (PCR-restriction fragment length polymorphism (RFLP. Materials and Methods : Genital swabs were taken from 210 patients. They were transported to the laboratory in phosphate-buffered saline. For PCR, samples were analysed with genus-specific MyUu-R and MyUu-F primers. This primer set, which was originally designed in our laboratory, amplified a 465 bp fragment (M. genitalium and a 559 bp fragment (U. urealyticum. Samples containing a band of the expected sizes for the Mycoplasma strains were subjected to digestion with a restriction endonuclease enzyme of TaqI and Cac8I. Results: Of the 210 samples, a total of 100 (47.6% samples were found to be positive for Mycoplasmas (seven M. genitalium isolates, 3.3%; and 89 U. urealyticum isolates, 42.4%, and coinfections with both species were detected in four samples (1.9%. The PCR-RFLP results showed that M. genitalium and U. urealyticum are different by enzyme patterns. Conclusion: PCR-RFLP offers a rapid and easily applicable protocol to simultaneous detection and differentiation of M. genitalium and U. urealyticum from clinical samples when specific primers and restriction enzymes are used.

  13. Staged Custom, Intramedullary Antibiotic Spacers for Severe Segmental Bone Loss in Infected Total Hip Arthroplasty

    Directory of Open Access Journals (Sweden)

    Atul F. Kamath

    2011-01-01

    Full Text Available Introduction. Total hip arthroplasty (THA infections with severe bone loss pose significant reconstructive challenges. We present our experience with two-stage hip reimplantation using an intramedullary, antibiotic-impregnated nail. Methods. Three patients with infected THA with severe proximal femoral bone loss (Mallory type IIIB or greater were treated using a custom antibiotic spacer. Clinical outcomes and any complications were recorded. Average followup was 49 months from final reimplantation. Results. Mean age at spacer placement (stage 1 was 53 years. The mean Harris Hip Score at final followup was 80. Two patients had asymptomatic heterotopic ossification, and one patient had a 2 cm leg-length discrepancy. Conclusions. A custom intramedullary nail antibiotic spacer is a reliable option in the staged management of the infected THA with severe proximal femoral bone loss. Benefits of this technique include limb salvage with maintenance of leg length, soft tissue tension, and functional status.

  14. Effect of alkyl chain length of imidazolium cations on the electron transport and recombination kinetics in ionic gel electrolytes based quasi-solid-state dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Huo, Zhipeng; Tao, Li; Wang, Lu; Zhu, Jun; Chen, Shuanghong; Zhang, Changneng; Dai, Songyuan; Zhang, Bing

    2015-01-01

    Highlights: •A series of novel IGEs based on 12-hydroxystearicacid as LMOG were prepared. •The QS-DSSCs exhibit excellent stability during the accelerated aging tests. •The influence of Im + alkyl chain length on the electron kinetic process is investigated. -- Abstract: A series of stable quasi-solid-state dye-sensitized solar cells (QS-DSSCs) are prepared by the 12-hydroxystearicacid as low molecular mass organogelator (LMOG) to gelate the ionic liquid with different alkyl chain lengths (3, 4, and 7). The influence of alkyl chain length of imidazolium cations (Im + ) on the kinetic processes of electron transport and recombination are investigated by Electrochemical impedance spectroscopy (EIS) and intensity-modulated photocurrent spectroscopy/intensity-modulated photovoltage spectroscopy (IMPS/IMVS). It is found that the ionic gel electrolytes (IGEs) with different alkyl chain lengths of Im + can influence the competitive adsorption effects of imidazolium cations (Im + ) and Li + , and further affect the charge diffusion, the electron recombination/transport processes, the shift of TiO 2 conduction band edge and surface states distribution. The IGE with longer alkyl chain length of Im + can prolong the electron recombination lifetime, promote the incidental photon-to-electron conversion efficiency (IPCE) and the short circuit photocurrent density (J sc ). An excellent QS-DSSC based on the IGE with the longer alkyl chain of Im + gives the highest photoelectric conversion efficiency. Moreover, all the QS-DSSCs based on IGEs exhibit excellent durability without losing their photovoltaic performances during the accelerated thermal and light–soaking test. These results are very important to the researches on the electrochemical mechanism and application of QS-DSSCs based on IGEs

  15. Fouling Resilient Perforated Feed Spacers for Membrane Filtration

    KAUST Repository

    Kerdi, Sarah; Qamar, Adnan; Vrouwenvelder, Johannes S.; Ghaffour, NorEddine

    2018-01-01

    drop across the spacer filled channel. The 3-Hole spacer was found to have the lowest pressure drop (50% - 61%) compared to 0-Hole spacer for various average flow velocities. Regarding permeate flux production, the 0-Hole spacer produced 5.7 L.m-2.h-1

  16. (99m)Tc-labeled gastrins of varying peptide chain length: Distinct impact of NEP/ACE-inhibition on stability and tumor uptake in mice.

    Science.gov (United States)

    Kaloudi, Aikaterini; Nock, Berthold A; Lymperis, Emmanouil; Krenning, Eric P; de Jong, Marion; Maina, Theodosia

    2016-06-01

    In situ inhibition of neutral endopeptidase (NEP) has been recently shown to impressively increase the bioavailability and tumor uptake of biodegradable gastrin radioligands. Furthermore, angiotensin converting enzyme (ACE) has been previously shown to cleave gastrin analogs in vitro. In the present study, we have assessed the effects induced by single or dual NEP/ACE-inhibition on the pharmacokinetic profile of three (99m)Tc-labeled gastrins of varying peptide chain length: [(99m)Tc]SG6 ([(99m)Tc-N4-Gln(1)]gastrin(1-17)), [(99m)Tc]DG2 ([(99m)Tc-N4-Gly(4),DGlu(5)]gastrin(4-17)) and [(99m)Tc]DG4 ([(99m)Tc-N4-DGlu(10)]gastrin(10-17)). Mouse blood samples were collected 5min after injection of each of [(99m)Tc]SG6/DG2/DG4 together with: a) vehicle, b) the NEP-inhibitor phosphoramidon (PA), c) the ACE-inhibitor lisinopril (Lis), or d) PA plus Lis and were analyzed by RP-HPLC for radiometabolite detection. Biodistribution was studied in SCID mice bearing A431-CCK2R(+/-) xenografts at 4h postinjection (pi). [(99m)Tc]SG6 or [(99m)Tc]DG4 was coinjected with either vehicle or the above described NEP/ACE-inhibitor regimens; for [(99m)Tc]DG2 control and PA animal groups were only included. Treatment of mice with PA induced significant stabilization of (99m)Tc-radiotracers in peripheral blood, while treatment with Lis or Lis+PA affected the stability of des(Glu)5 [(99m)Tc]DG4 only. In line with these findings, PA coinjection led to notable amplification of tumor uptake of radiopeptides compared to controls (PTc]DG4 profited by single Lis (2.06±0.39%ID/g vs 0.99±0.13%ID/g in controls) or combined Lis+PA coinjection (8.91±1.61%ID/g vs 4.89±1.33%ID/g in PA-group). Furthermore, kidney uptake remained favourably low and unaffected by PA and/or Lis coinjection only in the case of [(99m)Tc]DG4 (Tc-radioligands based on different-length gastrins. Truncated [(99m)Tc]DG4 exhibited overall the most attractive profile during combined NEP/ACE-inhibition in mouse models, providing new

  17. Simulation study of transfer characteristics for spacer-filled membrane distillation desalination modules

    International Nuclear Information System (INIS)

    Chang, Hsuan; Hsu, Jian-An; Chang, Cheng-Liang; Ho, Chii-Dong; Cheng, Tung-Wen

    2017-01-01

    Highlights: • A 3D CFD model takes in transmembrane heat and mass transfer developed. • DCMD modules using spacer-filled and empty channels for desalination simulated. • Fluid flow, heat transfer and mass transfer profiles revealed. • Correlations of friction factor and Nusselt number developed. - Abstract: Membrane distillation (MD) is an emerging and promising membrane separation process, which can directly utilize renewable thermal energy or low-grade waste heat, for applications in water or wastewater treatment and food industry. However, a major drawback of MD process is its low energy efficiency. Spacer is the most suggested and studied eddy promoter to enhance the heat and mass transfer, which further improves both the separation and the energy utilization performance, of MD processes. This paper presents the results of a 3D computational fluid dynamics (CFD) simulation of DCMD (direct contact membrane distillation) modules using channels with and without spacers for desalination application. The model employs permeable wall boundary condition to take into account the transmembrane heat and mass transfer and simulates the entire module length. The simulation reveals similar fluctuating distributions of temperature polarization coefficient, transmembrane heat and mass fluxes as well as the shear stress on the membrane surface along the entire module length. Correlations have been developed for friction factor and average Nusselt number. These correlations are useful for the analysis and design of DCMD modules. The extent of heat transfer enhancement by spacers depends on the geometry of spacers and the Reynolds number of fluid.

  18. Production of medium-chain-length polyhydroxyalkanoates by sequential feeding of xylose and octanoic acid in engineered Pseudomonas putida KT2440

    Directory of Open Access Journals (Sweden)

    Le Meur Sylvaine

    2012-08-01

    Full Text Available Abstract Background Pseudomonas putida KT2440 is able to synthesize large amounts of medium-chain-length polyhydroxyalkanoates (mcl-PHAs. To reduce the substrate cost, which represents nearly 50% of the total PHA production cost, xylose, a hemicellulose derivate, was tested as the growth carbon source in an engineered P. putida KT2440 strain. Results The genes encoding xylose isomerase (XylA and xylulokinase (XylB from Escherichia coli W3110 were introduced into P. putida KT2440. The recombinant KT2440 exhibited a XylA activity of 1.47 U and a XylB activity of 0.97 U when grown on a defined medium supplemented with xylose. The cells reached a maximum specific growth rate of 0.24 h-1 and a final cell dry weight (CDW of 2.5 g L-1 with a maximal yield of 0.5 g CDW g-1 xylose. Since no mcl-PHA was accumulated from xylose, mcl-PHA production can be controlled by the addition of fatty acids leading to tailor-made PHA compositions. Sequential feeding strategy was applied using xylose as the growth substrate and octanoic acid as the precursor for mcl-PHA production. In this way, up to 20% w w-1 of mcl-PHA was obtained. A yield of 0.37 g mcl-PHA per g octanoic acid was achieved under the employed conditions. Conclusions Sequential feeding of relatively cheap carbohydrates and expensive fatty acids is a practical way to achieve more cost-effective mcl-PHA production. This study is the first reported attempt to produce mcl-PHA by using xylose as the growth substrate. Further process optimizations to achieve higher cell density and higher productivity of mcl-PHA should be investigated. These scientific exercises will undoubtedly contribute to the economic feasibility of mcl-PHA production from renewable feedstock.

  19. Transcriptome analysis of Pseudomonas mediterranea and P. corrugata plant pathogens during accumulation of medium-chain-length PHAs by glycerol bioconversion.

    Science.gov (United States)

    Licciardello, Grazia; Ferraro, Rosario; Russo, Marcella; Strozzi, Francesco; Catara, Antonino F; Bella, Patrizia; Catara, Vittoria

    2017-07-25

    Pseudomonas corrugata and P. mediterranea are soil inhabitant bacteria, generally living as endophytes on symptomless plants and bare soil, but also capable of causing plant diseases. They share a similar genome size and a high proteome similarity. P. corrugata produces many biomolecules which play an important role in bacterial cell survival and fitness. Both species produce different medium-chain-length PHAs (mcl-PHAs) from the bioconversion of glycerol to a transparent film in P. mediterranea and a sticky elastomer in P. corrugata. In this work, using RNA-seq we investigated the transcriptional profiles of both bacteria at the early stationary growth phase with glycerol as the carbon source. Quantitative analysis of P. mediterranea transcripts versus P. corrugata revealed that 1756 genes were differentially expressed. A total of 175 genes were significantly upregulated in P. mediterranea, while 217 were downregulated. The largest group of upregulated genes was related to transport systems and stress response, energy and central metabolism, and carbon metabolism. Expression levels of most genes coding for enzymes related to PHA biosynthesis and central metabolic pathways showed no differences or only slight variations in pyruvate metabolism. The most relevant result was the significantly increased expression in P. mediterranea of genes involved in alginate production, an important exopolysaccharide, which in other Pseudomonas spp. plays a key role as a virulence factor or in stress tolerance and shows many industrial applications. In conclusion, the results provide useful information on the co-production of mcl-PHAs and alginate from glycerol as carbon source by P. mediterranea in the design of new strategies of genetic regulation to improve the yield of bioproducts or bacterial fitness. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Investigation of the role of hydrophilic chain length in amphiphilic perfluoropolyether/poly(ethylene glycol) networks: towards high-performance antifouling coatings

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yapei; Pitet, Louis M.; Finlay, John A.; Brewer, Lenora H.; Cone, Gemma; Betts, Douglas E.; Callow, Maureen E.; Callow, James A.; Wendt, Dean E.; Hillmyer, Marc A.; DeSimone, Joseph M. (Birmingham UK); (NCSU); (UNC); (Cal. Polytech.); (UMM)

    2013-03-07

    The facile preparation of amphiphilic network coatings having a hydrophobic dimethacryloxy-functionalized perfluoropolyether (PFPE-DMA; M{sub w} = 1500 g mol{sup -1}) crosslinked with hydrophilic monomethacryloxy functionalized poly(ethylene glycol) macromonomers (PEG-MA; M{sub w} = 300, 475, 1100 g mol{sup -1}), intended as non-toxic high-performance marine coatings exhibiting antifouling characteristics is demonstrated. The PFPE-DMA was found to be miscible with the PEG-MA. Photo-cured blends of these materials containing 10 wt% of PEG-MA oligomers did not swell significantly in water. PFPE-DMA crosslinked with the highest molecular weight PEG oligomer (ie PEG1100) deterred settlement (attachment) of algal cells and cypris larvae of barnacles compared to a PFPE control coating. Dynamic mechanical analysis of these networks revealed a flexible material. Preferential segregation of the PEG segments at the polymer/air interface resulted in enhanced antifouling performance. The cured amphiphilic PFPE/PEG films showed decreased advancing and receding contact angles with increasing PEG chain length. In particular, the PFPE/PEG1100 network had a much lower advancing contact angle than static contact angle, suggesting that the PEG1100 segments diffuse to the polymer/water interface quickly. The preferential interfacial aggregation of the larger PEG segments enables the coating surface to have a substantially enhanced resistance to settlement of spores of the green seaweed Ulva, cells of the diatom Navicula and cypris larvae of the barnacle Balanus amphitrite as well as low adhesion of sporelings (young plants) of Ulva, adhesion being lower than to a polydimethyl elastomer, Silastic T2.

  1. Investigation of the role of hydrophilic chain length in amphiphilic perfluoropolyether/poly(ethylene glycol) networks: towards high-performance antifouling coatings.

    Science.gov (United States)

    Wang, Yapei; Pitet, Louis M; Finlay, John A; Brewer, Lenora H; Cone, Gemma; Betts, Douglas E; Callow, Maureen E; Callow, James A; Wendt, Dean E; Hillmyer, Marc A; DeSimonea, Joseph M

    2011-01-01

    The facile preparation of amphiphilic network coatings having a hydrophobic dimethacryloxy-functionalized perfluoropolyether (PFPE-DMA; M(w) = 1500 g mol(-1)) crosslinked with hydrophilic monomethacryloxy functionalized poly(ethylene glycol) macromonomers (PEG-MA; M(w) = 300, 475, 1100 g mol(-1)), intended as non-toxic high-performance marine coatings exhibiting antifouling characteristics is demonstrated. The PFPE-DMA was found to be miscible with the PEG-MA. Photo-cured blends of these materials containing 10 wt% of PEG-MA oligomers did not swell significantly in water. PFPE-DMA crosslinked with the highest molecular weight PEG oligomer (ie PEG1100) deterred settlement (attachment) of algal cells and cypris larvae of barnacles compared to a PFPE control coating. Dynamic mechanical analysis of these networks revealed a flexible material. Preferential segregation of the PEG segments at the polymer/air interface resulted in enhanced antifouling performance. The cured amphiphilic PFPE/PEG films showed decreased advancing and receding contact angles with increasing PEG chain length. In particular, the PFPE/PEG1100 network had a much lower advancing contact angle than static contact angle, suggesting that the PEG1100 segments diffuse to the polymer/water interface quickly. The preferential interfacial aggregation of the larger PEG segments enables the coating surface to have a substantially enhanced resistance to settlement of spores of the green seaweed Ulva, cells of the diatom Navicula and cypris larvae of the barnacle Balanus amphitrite as well as low adhesion of sporelings (young plants) of Ulva, adhesion being lower than to a polydimethyl elastomer, Silastic T2.

  2. Effect of molecular chain length on the mechanical and thermal properties of amine-functionalized graphene oxide/polyimide composite films prepared by in situ polymerization.

    Science.gov (United States)

    Liao, Wei-Hao; Yang, Shin-Yi; Wang, Jen-Yu; Tien, Hsi-Wen; Hsiao, Sheng-Tsung; Wang, Yu-Sheng; Li, Shin-Ming; Ma, Chen-Chi M; Wu, Yi-Fang

    2013-02-01

    This study fabricates amine (NH(2))-functionalized graphene oxide (GO)/polyimide(PI) composite films with high performance using in situ polymerization. Linear poly(oxyalkylene)amines with two different molecular weights 400 and 2000 (D400 and D2000) have been grafted onto the GO surfaces, forming two types of NH(2)-functionalized GO (D400-GO/D2000-GO). NH(2)-functionalized GO, especially D400-GO, demonstrated better reinforcing efficiency in mechanical and thermal properties. The observed property enhancement are due to large aspect ratio of GO sheets, the uniform dispersion of the GO within the PI matrix, and strong interfacial adhesion due to the chemical bonding between GO and the polymeric matrix. The Young's modulus of the composite films with 0.3 wt % D400-GO loading is 7.4 times greater than that of neat PI, and tensile strength is 240% higher than that of neat PI. Compared to neat PI, 0.3 wt % D400-GO/PI film exhibits approximately 23.96 °C increase in glass transition temperature (T(g)). The coefficient of thermal expansion below T(g) is significantly decreased from 102.6 μm/°C (neat PI) to 53.81 μm/°C (decreasing 48%) for the D400-GO/PI composites with low D400-GO content (0.1 wt %). This work not only provides a method to develop the GO-based polyimide composites with superior performances but also conceptually provides a chance to modulate the interfacial interaction between GO and the polymer through designing the chain length of grafting molecules on NH(2)-functionalized GO.

  3. Experimental investigation of heat transfer and friction factor characteristics of thermosyphon solar water heater system fitted with spacer at the trailing edge of Left-Right twisted tapes

    International Nuclear Information System (INIS)

    Jaisankar, S.; Radhakrishnan, T.K.; Sheeba, K.N.; Suresh, S.

    2009-01-01

    Experimental investigation of heat transfer and friction factor characteristics of thermosyphon solar water heater with full length Left-Right twist, twist fitted with rod and spacer at the trailing edge for lengths of 100, 200 and 300 mm for twist ratio 3 and 5 has been studied. The experimental data for plain tube collector has been compared with fundamental equation within a discrepancy of ±7.41% and ±14.97% for Nusselt number and friction factor, respectively. Result shows that the Nusselt number decreases by 11% and 19% for twist fitted with rod and twist with spacer, respectively, when compared with full length twist. Friction factor also decreases by 18% and 29% for twist fitted with rod and spacer, respectively, as compared with full length twist. The heat enhancement in twist fitted with rod at the trailing edge is maximum when compared with twist fitted with spacer because the swirl flow is maintained throughout the length of rod.

  4. Characterization of four species of Trichuris (Nematoda: Enoplida) by their second internal transcribed spacer ribosomal DNA sequence.

    Science.gov (United States)

    Oliveros, R; Cutillas, C; De Rojas, M; Arias, P

    2000-12-01

    Adult worms of Trichuris ovis and T. globulosa were collected from Ovis aries (sheep) and Capra hircus (goats). T. suis was isolated from Sus scrofa domestica (swine) and T. leporis was isolated from Lepus europaeus (rabbits) in Spain. Genomic DNA was isolated and a ribosomal internal transcribed spacer (ITS2) was amplified and sequenced using polymerase-chain-reaction (PCR) techniques. The ITS2 of T. ovis and T. globulosa was 407 nucleotides in length and had a GC content of about 62%. Furthermore, the ITS2 of T. suis and T. leporis was 534 and 418 nucleotides in length and had a GC content of about 64.8% and 62.4%, respectively. There was evidence of slight variation in the sequence within individuals of all species analyzed, indicating intraindividual variation in the sequence of different copies of the ribosomal DNA. Furthermore, low-level intraspecific variation was detected. Sequence analyses of ITS2 products of T. ovis and T. globulosa demonstrated no sequence difference between them. Nevertheless, differences were detected between the ITS2 sequences of T. suis, T. leporis, and T. ovis, indicating that Trichuris species can reliably be differentiated by their ITS2 sequences and PCR-linked restriction-fragment-length polymorphism (RFLP).

  5. High corrosion-resistant fuel spacers

    International Nuclear Information System (INIS)

    Yoshida, Toshimi; Takase, Iwao; Ikeda, Shinzo; Masaoka, Isao; Nakajima, Junjiro.

    1986-01-01

    Purpose: To enable manufacturing BWR fuel spacers by prior-art production process, using a zirconium-base alloy having very excellent corrosion resistance. Method: A highly improved nodular-resistant, corrosion-resistant zirconium alloy is devised by adding a slight amount of niobium, titanium and vanadium to zircaloy, of which fuel spacers are produced. That is, there can be obtained an alloy having much more excellent nodular resistance than conventional zircaloy, and free from a large change in plasticity, workability, and weldability, by adding to zirconium about 1.5 % of tin, about 0.15 % of iron, about 0.05 % of chromium, about 0.05 % of nickel, and 0.05 to 0.5 % of at least one or two kinds of niobium, titanium and vanadium. Using this zirconium-base alloy can manufacture fuel spacers by the same manufacturing process, thus improving economy and reliability. (Kamimura, M.)

  6. Novel phytoceramides containing fatty acids of diverse chain lengths are better than a single C18-ceramide N-stearoyl phytosphingosine to improve the physiological properties of human stratum corneum

    Directory of Open Access Journals (Sweden)

    Oh MJ

    2017-09-01

    Full Text Available Myoung Jin Oh,1 Young Hoon Cho,1 So Yoon Cha,1 Eun Ok Lee,2 Jin Wook Kim,2 Sun Ki Kim,2 Chang Seo Park1 1Department of Chemical and Biochemical Engineering, Dongguk University, Chung-gu, Seoul, 2LCS Biotech, Gwonseon-gu, Suwon-si, Gyeonggi-do, Republic of Korea Abstract: Ceramides in the human stratum corneum (SC are a mixture of diverse N-acylated fatty acids (FAs with different chain lengths. C24 is the major class of FAs of ceramides. However, there are also other classes of ceramides with diverse chain lengths of FAs, and these lengths generally range from C16 to C26. This study aimed to prepare several types of phytoceramide containing diverse chain lengths of N-acylated FAs and compare them with C18-ceramide N-stearoyl phytosphingosine (NP in terms of their effects on the physiological properties of the SC. We chose natural oils, such as horse fat oil, shea butter, sunflower oil, and a mixture of macadamia nut, shea butter, moringa, and meadowfoam seed oil, as sources of FAs and phytosphingosine as a sphingoid backbone to synthesize diverse phytoceramides. Each phytoceramide exhibited a distinctive formation of the lamellar structure, and their FA profiles were similar to those of their respective natural oil. The skin barrier properties, as analyzed in human skin, clearly demonstrated that all the phytoceramides improved the recovery rate of the damaged SC and enhanced hydration better than C18-ceramide NP did. In conclusion, natural oil-derived phytoceramides could represent a novel class of ceramides for cosmetic applications in the development of an ideal skin barrier moisturizer. Keywords: fatty acid, chain length, phytoceramide, skin barrier, natural oil

  7. A reduction in growth rate of Pseudomonas putida KT2442 counteracts productivity advances in medium-chain-length polyhydroxyalkanoate production from gluconate

    Directory of Open Access Journals (Sweden)

    Zinn Manfred

    2011-04-01

    Full Text Available Abstract Background The substitution of plastics based on fossil raw material by biodegradable plastics produced from renewable resources is of crucial importance in a context of oil scarcity and overflowing plastic landfills. One of the most promising organisms for the manufacturing of medium-chain-length polyhydroxyalkanoates (mcl-PHA is Pseudomonas putida KT2440 which can accumulate large amounts of polymer from cheap substrates such as glucose. Current research focuses on enhancing the strain production capacity and synthesizing polymers with novel material properties. Many of the corresponding protocols for strain engineering rely on the rifampicin-resistant variant, P. putida KT2442. However, it remains unclear whether these two strains can be treated as equivalent in terms of mcl-PHA production, as the underlying antibiotic resistance mechanism involves a modification in the RNA polymerase and thus has ample potential for interfering with global transcription. Results To assess PHA production in P. putida KT2440 and KT2442, we characterized the growth and PHA accumulation on three categories of substrate: PHA-related (octanoate, PHA-unrelated (gluconate and poor PHA substrate (citrate. The strains showed clear differences of growth rate on gluconate and citrate (reduction for KT2442 > 3-fold and > 1.5-fold, respectively but not on octanoate. In addition, P. putida KT2442 PHA-free biomass significantly decreased after nitrogen depletion on gluconate. In an attempt to narrow down the range of possible reasons for this different behavior, the uptake of gluconate and extracellular release of the oxidized product 2-ketogluconate were measured. The results suggested that the reason has to be an inefficient transport or metabolization of 2-ketogluconate while an alteration of gluconate uptake and conversion to 2-ketogluconate could be excluded. Conclusions The study illustrates that the recruitment of a pleiotropic mutation, whose effects might

  8. Comparative analysis of human cytomegalovirus a-sequence in multiple clinical isolates by using polymerase chain reaction and restriction fragment length polymorphism assays.

    Science.gov (United States)

    Zaia, J A; Gallez-Hawkins, G; Churchill, M A; Morton-Blackshere, A; Pande, H; Adler, S P; Schmidt, G M; Forman, S J

    1990-01-01

    The human cytomegalovirus (HCMV) a-sequence (a-seq) is located in the joining region between the long (L) and short (S) unique sequences of the virus (L-S junction), and this hypervariable junction has been used to differentiate HCMV strains. The purpose of this study was to investigate whether there are differences among strains of human cytomegalovirus which could be characterized by polymerase chain reaction (PCR) amplification of the a-seq of HCMV DNA and to compare a PCR method of strain differentiation with conventional restriction fragment length polymorphism (RFLP) methodology by using HCMV junction probes. Laboratory strains of HCMV and viral isolates from individuals with HCMV infection were characterized by using both RFLPs and PCR. The PCR assay amplified regions in the major immediate-early gene (IE-1), the 64/65-kDa matrix phosphoprotein (pp65), and the a-seq of the L-S junction region. HCMV laboratory strains Towne, AD169, and Davis were distinguishable, in terms of size of the amplified product, when analyzed by PCR with primers specific for the a-seq but were indistinguishable by using PCR targeted to IE-1 and pp65 sequences. When this technique was applied to a characterization of isolates from individuals with HCMV infection, selected isolates could be readily distinguished. In addition, when the a-seq PCR product was analyzed with restriction enzyme digestion for the presence of specific sequences, these DNA differences were confirmed. PCR analysis across the variable a-seq of HCMV demonstrated differences among strains which were confirmed by RFLP in 38 of 40 isolates analyzed. The most informative restriction enzyme sites in the a-seq for distinguishing HCMV isolates were those of MnlI and BssHII. This indicates that the a-seq of HCMV is heterogeneous among wild strains, and PCR of the a-seq of HCMV is a practical way to characterize differences in strains of HCMV. Images PMID:1980680

  9. 99mTc-labeled gastrins of varying peptide chain length: Distinct impact of NEP/ACE-inhibition on stability and tumor uptake in mice

    International Nuclear Information System (INIS)

    Kaloudi, Aikaterini; Nock, Berthold A.; Lymperis, Emmanouil; Krenning, Eric P.; Jong, Marion de; Maina, Theodosia

    2016-01-01

    Introduction: In situ inhibition of neutral endopeptidase (NEP) has been recently shown to impressively increase the bioavailability and tumor uptake of biodegradable gastrin radioligands. Furthermore, angiotensin converting enzyme (ACE) has been previously shown to cleave gastrin analogs in vitro. In the present study, we have assessed the effects induced by single or dual NEP/ACE-inhibition on the pharmacokinetic profile of three 99m Tc-labeled gastrins of varying peptide chain length: [ 99m Tc]SG6 ([ 99m Tc-N 4 -Gln 1 ]gastrin(1–17)), [ 99m Tc]DG2 ([ 99m Tc-N 4 -Gly 4 ,DGlu 5 ]gastrin(4–17)) and [ 99m Tc]DG4 ([ 99m Tc-N 4 -DGlu 10 ]gastrin(10–17)). Methods: Mouse blood samples were collected 5 min after injection of each of [ 99m Tc]SG6/DG2/DG4 together with: a) vehicle, b) the NEP-inhibitor phosphoramidon (PA), c) the ACE-inhibitor lisinopril (Lis), or d) PA plus Lis and were analyzed by RP-HPLC for radiometabolite detection. Biodistribution was studied in SCID mice bearing A431-CCK2R(+/−) xenografts at 4 h postinjection (pi). [ 99m Tc]SG6 or [ 99m Tc]DG4 was coinjected with either vehicle or the above described NEP/ACE-inhibitor regimens; for [ 99m Tc]DG2 control and PA animal groups were only included. Results: Treatment of mice with PA induced significant stabilization of 99m Tc-radiotracers in peripheral blood, while treatment with Lis or Lis + PA affected the stability of des(Glu) 5 [ 99m Tc]DG4 only. In line with these findings, PA coinjection led to notable amplification of tumor uptake of radiopeptides compared to controls (P < 0.01). Only [ 99m Tc]DG4 profited by single Lis (2.06 ± 0.39%ID/g vs 0.99 ± 0.13%ID/g in controls) or combined Lis + PA coinjection (8.91 ± 1.61%ID/g vs 4.89 ± 1.33%ID/g in PA-group). Furthermore, kidney uptake remained favourably low and unaffected by PA and/or Lis coinjection only in the case of [ 99m Tc]DG4 (< 1.9%ID/g) resulting in the most optimal tumor-to-kidney ratios. Conclusions: In situ NEP

  10. A high-performance channel engineered charge-plasma-based MOSFET with high-κ spacer

    Science.gov (United States)

    Shan, Chan; Wang, Ying; Luo, Xin; Bao, Meng-tian; Yu, Cheng-hao; Cao, Fei

    2017-12-01

    In this paper, the performance of graded channel double-gate MOSFET (GC-DGFET) that utilizes the charge-plasma concept and a high-κ spacer is investigated through 2-D device simulations. The results demonstrate that GC-DGFET with high-κ spacer can effectively improve the ON-state driving current (ION) and reduce the OFF-leakage current (IOFF). We find that reduction of the initial energy barrier between the source and channel is the origin of this ION enhancement. The reason for the IOFF reduction is identified to be the extension of the effective channel length owing to the fringing field via high-κ spacers. Consequently, these devices offer enhanced performance by reducing the total gate-to-gate capacitance (Cgg) and decreasing the intrinsic delay (τ).

  11. Fouling Resilient Perforated Feed Spacers for Membrane Filtration

    KAUST Repository

    Kerdi, Sarah

    2018-04-24

    The improvement of feed spacers with optimal geometry remains a key challenge for spiral-wound membrane systems in water treatment due to their impact on the hydrodynamic performance and fouling development. In this work, novel spacer designs are proposed by intrinsically modifying cylindrical filaments through perforations. Three symmetric perforated spacers (1-Hole, 2-Hole, and 3-Hole) were in-house 3D-printed and experimentally evaluated in terms of permeate flux, feed channel pressure drop and membrane fouling. Spacer performance is characterized and compared with standard no perforated (0-Hole) design under constant feed pressure and constant feed flow rate. Perforations in the spacer filaments resulted in significantly lowering the net pressure drop across the spacer filled channel. The 3-Hole spacer was found to have the lowest pressure drop (50% - 61%) compared to 0-Hole spacer for various average flow velocities. Regarding permeate flux production, the 0-Hole spacer produced 5.7 L.m-2.h-1 and 6.6 L.m-2.h-1 steady state flux for constant pressure and constant feed flow rate, respectively. The 1-Hole spacer was found to be the most efficient among the perforated spacers with 75% and 23% increase in permeate production at constant pressure and constant feed flow, respectively. Furthermore, membrane surface of 1-Hole spacer was found to be cleanest in terms of fouling, contributing to maintain higher permeate flux production. Hydrodynamic understanding of these perforated spacers is also quantified by performing Direct Numerical Simulation (DNS). The performance enhancement of these perforated spacers is attributed to the formation of micro-jets in the spacer cell that aided in producing enough unsteadiness/turbulence to clean the membrane surface and mitigate fouling phenomena. In the case of 1-Hole spacer, the unsteadiness intensity at the outlet of micro-jets and the shear stress fluctuations created inside the cells are higher than those observed with

  12. Nuclear reactor fuel assembly spacer grids

    International Nuclear Information System (INIS)

    Jabsen, F.S.

    1977-01-01

    Designs of nuclear reactor fuel assembly spacer grids for supporting and spacing fuel elements are described which do not utilize resilient grid plate protrusions in the peripheral band but retain the advantages inherent in the combination resilient and rigid protrusion cells. (U.K.)

  13. Separator-spacer for electrochemical systems

    Science.gov (United States)

    Grimes, Patrick G.; Einstein, Harry; Newby, Kenneth R.; Bellows, Richard J.

    1983-08-02

    An electrochemical cell construction features a novel co-extruded plastic electrode in an interleaved construction with a novel integral separator-spacer. Also featured is a leak and impact resistant construction for preventing the spill of corrosive materials in the event of rupture.

  14. Nuclear reactor spring strip grid spacer

    International Nuclear Information System (INIS)

    Patterson, J.F.; Flora, B.S.

    1980-01-01

    An improved and novel grid spacer for maintaining the fuel rods of a nuclear reactor fuel assembly in substantially parallel array is described. The invention provides for spring strips to maintain the fuel elements in their desired orientation which have more positive alignment than previous types while allowing greater flexibility to counterbalance the effects of differential thermal expansion. (UK)

  15. Rotational diffusion of nonpolar and ionic solutes in 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imides: is solute rotation always influenced by the length of the alkyl chain on the imidazolium cation?

    Science.gov (United States)

    Gangamallaiah, V; Dutt, G B

    2012-10-25

    In an attempt to find out whether the length of the alkyl chain on the imidazolium cation has a bearing on solute rotation, temperature-dependent fluorescence anisotropies of three structurally similar solutes have been measured in a series of 1-alkyl-3-methylimidazolium (alkyl = methyl, ethyl, propyl, butyl, and hexyl) bis(trifluoromethylsulfonyl)imides. Solute-solvent coupling constants obtained from the experimentally measured reorientation times with the aid of Stokes-Einstein-Debye hydrodynamic theory indicate that there is no influence of the length of the alkyl chain on the rotation of nonpolar, anionic, and cationic solutes 9-phenylanthracene (9-PA), fluorescein (FL), and rhodamine 110 (R110), respectively. It has also been noticed that the rotational diffusion of 9-PA is closer to the predictions of slip hydrodynamics, whereas the rotation of negatively charged FL and positively charged R110 is almost identical and follows stick hydrodynamics in these ionic liquids. Despite having similar shape and size, ionic solutes rotate slower by a factor of 3-4 compared to the nonpolar solute. Interplay of specific and electrostatic interactions between FL and the imidazolium cation of the ionic liquids, and between R110 and the bis(trifluoromethylsulfonyl)imide anion, appear to be responsible for the observed behavior. These results are an indication that the length of the alkyl chain on the imidazolium cation does not alter their physical properties in a manner that has an effect on solute rotation.

  16. Flow behavior of droplets downstream of the spacer

    International Nuclear Information System (INIS)

    Kodama, Eiichiro; Morishita, Kiyohide; Aritomi, Masanori; Yano, Takashi

    1998-01-01

    The fuel spacer, of which role is to maintain an appropriate rod-to-rod clearance, is one of the components of a Boiling Water Reactor (BWR) fuel rod bundles. The fuel spacer influences flow characteristics of the liquid film in fuel rod bundles, so that its geometry influences greatly thermal hydraulics such as critical power and pressure drop therein. The purpose of this study is to clarify the effect of the spacer geometry on the core flow split downstream of the spacer. Phase Doppler Anemometry (PDA) was used for their meausrement under the conditions of a small amount of droplets in mist flows. From the experimental results, the normalized droplet velocity profiles with a spacer were split by the spacer and were different between a wider and a narrower regions in the channel, however, they became uniform at the distance far 100mm from the spacer. In the case without a spacer, the velocity was monotonously increasing nearer the rod surface with going toward the center of the channel. In the case with a spacer, the velocity profile downstream of the spacer changed in the narrower region of the channel. This tendency became more remarkable with thickening the spacer and widening clearance between the spacer and the wall. In this paper, 'drift' velocity effect was applied for the spacer model, due to the gas flows were split by the spacer which is based on the momentum balance between the narrower and wider channels. This model was confirmed from the experimental results that the droplet flowed from a wider region to a narrower one. This drift effect appeared more strongly as the spacer became thicker and the clearance did narrower. The analytical results explained qualitatively the measured ones. It is clarified that the drift effect proposed in this work was a dominant factor on droplet deposition downstream of the spacer

  17. PMMA-g-OEtOx Graft Copolymers: Influence of Grafting Degree and Side Chain Length on the Conformation in Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Irina Muljajew

    2018-03-01

    Full Text Available Depending on the degree of grafting (DG and the side chain degree of polymerization (DP, graft copolymers may feature properties similar to statistical copolymers or to block copolymers. This issue is approached by studying aqueous solutions of PMMA-g-OEtOx graft copolymers comprising a hydrophobic poly(methyl methacrylate (PMMA backbone and hydrophilic oligo(2-ethyl-2-oxazoline (OEtOx side chains. The graft copolymers were synthesized via reversible addition-fragmentation chain transfer (RAFT copolymerization of methyl methacrylate (MMA and OEtOx-methacrylate macromonomers of varying DP. All aqueous solutions of PMMA-g-OEtOx (9% ≤ DG ≤ 34%; 5 ≤ side chain DP ≤ 24 revealed lower critical solution temperature behavior. The graft copolymer architecture significantly influenced the aggregation behavior, the conformation in aqueous solution and the coil to globule transition, as verified by means of turbidimetry, dynamic light scattering, nuclear magnetic resonance spectroscopy, and analytical ultracentrifugation. The aggregation behavior of graft copolymers with a side chain DP of 5 was significantly affected by small variations of the DG, occasionally forming mesoglobules above the cloud point temperature (Tcp, which was around human body temperature. On the other hand, PMMA-g-OEtOx with elongated side chains assembled into well-defined structures below the Tcp (apparent aggregation number (Nagg = 10 that were able to solubilize Disperse Orange 3. The thermoresponsive behavior of aqueous solutions thus resembled that of micelles comprising a poly(2-ethyl-2-oxazoline (PEtOx shell (Tcp > 60 °C.

  18. Alkyl chain interaction at the surface of room temperature ionic liquids: systematic variation of alkyl chain length (R = C(1)-C(4), C(8)) in both cation and anion of [RMIM][R-OSO(3)] by sum frequency generation and surface tension.

    Science.gov (United States)

    Santos, Cherry S; Baldelli, Steven

    2009-01-29

    The gas-liquid interface of halide-free 1,3-dialkylimidazolium alkyl sulfates [RMIM][R-OSO(3)] with R chain length from C(1)-C(4) and C(8) has been studied systematically using the surface-specific sum frequency generation (SFG) vibrational spectroscopy and surface tension measurements. From the SFG spectra, vibrational modes from the methyl group of both cation and anion are observed for all ionic liquid samples considered in the present study. These results suggest the presence of both ions at the gas-liquid interface, which is further supported by surface tension measurements. Surface tension data show a decreasing trend as the alkyl chain in the imidazolium cation is varied from methyl to butyl chain, with a specific anion. A similar trend is observed when the alkyl chain of the anion is modified and the cation is fixed.

  19. Genomic DNA fingerprinting of clinical Haemophilus influenzae isolates by polymerase chain reaction amplification: comparison with major outer-membrane protein and restriction fragment length polymorphism analysis

    NARCIS (Netherlands)

    van Belkum, A.; Duim, B.; Regelink, A.; Möller, L.; Quint, W.; van Alphen, L.

    1994-01-01

    Non-capsulate strains of Haemophilus influenzae were genotyped by analysis of variable DNA segments obtained by amplification of genomic DNA with the polymerase chain reaction (PCR fingerprinting). Discrete fragments of 100-2000 bp were obtained. The reproducibility of the procedure was assessed by

  20. Probing the effects of the ester functional group, alkyl side chain length and anions on the bulk nanostructure of ionic liquids: a computational study.

    Science.gov (United States)

    Fakhraee, Mostafa; Gholami, Mohammad Reza

    2016-04-14

    The effects of ester addition on nanostructural properties of biodegradable ILs composed of 1-alkoxycarbonyl-3-alkyl-imidazolium cations ([C1COOCnC1im](+), n = 1, 2, 4) combined with [Br](-), [NO3](-), [BF4](-), [PF6](-), [TfO](-), and [Tf2N](-) were explored by using the molecular dynamics (MD) simulations and quantum theory of atoms in molecules (QTAIM) analysis at 400 K. Various thermodynamic properties of these ILs were extensively computed in our earlier work (Ind. Eng. Chem. Res., 2015, 54, 11678-11700). Nano-scale segregation analysis demonstrates the formation of a small spherical island-like hydrocarbon within the continuous ionic domain for ILs with short alkyl side chain ([C1COOC1C1im]), and a sponge-like nanostructure for the compound with long alkyl side chain ([C1COOC4C1im]). Ester-functionalized ILs with ethyl side chain ([C1COOC2C1im]) are the turning point between two different morphologies. Non-polar channels were observed for [C1COOC4C1im] ILs composed of smaller anions such as [Br] and [NO3], whereas clustering organization was found for the other anions. Formation of the spherical micelle-like nanostructure was seen for lengthened cations. Finally, the incorporation of an ester group into the alkyl side chain of the cation leads to stronger segregation between charged and uncharged networks, which consequently increased the possibility of self-assembly and micelle formation.

  1. Heterogeneous diversity of spacers within CRISPR

    Science.gov (United States)

    Deem, Michael; He, Jiankui

    2011-03-01

    Clustered regularly interspaced short palindromic repeats (CRISPR) in bacterial and archaeal DNA have recently been shown to be a new type of anti-viral immune system in these organisms. We here study the diversity of spacers in CRISPR under selective pressure. We propose a population dynamics model that explains the biological observation that the leader-proximal end of CRISPR is more diversified and the leader-distal end of CRISPR is more conserved. This result is shown to be in agreement with recent experiments. Our results show that the CRISPR spacer structure is influenced by and provides a record of the viral challenges that bacteria face. 1) J. He and M. W. Deem, Phys. Rev. Lett. 105 (2010) 128102

  2. Mechanical test for fuel assembly spacer grid

    International Nuclear Information System (INIS)

    Kang, Heung Seok; Jeong, Yeon Ho; Song, Kee Nam; Kim, Hyung Kyu; Yoon, Kyung Ho; Bang, Je Keun.

    1997-06-01

    In order to propose some tests for a new spacer grid, the grid mechanical tests performed by ABB-CE, KWU and Westinghouse have been investigated. It is known that a static compression test, a dynamic impact test, and a grid spring characteristic test were commonly carried out by the vendors when a prototype spacer grid was developed. The static compression test is to measure the stresses on the strips as well as to obtain the grid stiffness. The dynamic impact test is to get some basic data for accident analysis such as impact stiffness, impact strength, and coefficient of restitution. Since each fuel vendor has his theory on an accident analysis, every vendor employs his particular method for the dynamic impact test. The dynamic impact test can be divided into two in accordance with the number of impact face, and the duration of impact pulse. One is an one-sided impact test and the other is an through-gird impact test. The duration of the impact pulse for the former is considerably shorter than the latter. Therefore, the grid can endure much higher load under the one-sided impact condition than under the through-grid impact condition. The grid spring characteristic test is to obtain a force versus deflection curve. This curve is very important in designing the spacer grid to provide fuel rods with a sound supports in core. (author). 18 tabs., 26 figs

  3. Antibiotic impregnated total femur spacers: a technical tip

    Directory of Open Access Journals (Sweden)

    Colin D. Canham, MD

    2018-03-01

    Full Text Available Simultaneous prosthetic joint infection of ipsilateral hip and knee arthroplasties is often accompanied by significant bone loss and presents a challenging reconstructive problem. Two-stage reconstruction is favored and requires the placement of a total femur spacer, which is not a commercially available device. We describe a surgical technique, reporting on 2 cases in which a customized total femur antibiotic impregnated spacer was created by combining an articulating knee spacer and an articulating hip spacer with a reinforced cement dowel construct connecting the 2 spacers. Custom total femoral spacers are useful in the management of infected femoral megaprostheses and cases with ipsilateral injected hip and knee arthroplasties and severe femoral bone loss. Keywords: total femur spacer, revision arthroplasty, total hip arthroplasty, total knee arthroplasty, prosthetic joint infection

  4. Influence of chain length of pyrene fatty acids on their uptake and metabolism by Epstein-Barr-virus-transformed lymphoid cell lines from a patient with multisystemic lipid storage myopathy and from control subjects.

    OpenAIRE

    Radom, J; Salvayre, R; Levade, T; Douste-Blazy, L

    1990-01-01

    The uptake and intracellular metabolism of 4-(1-pyrene)butanoic acid (P4), 10-(1-pyrene)decanoic acid (P10) and 12-(1-pyrene)dodecanoic acid (P12) were investigated in cultured lymphoid cell lines from normal individuals and from a patient with multisystemic lipid storage myopathy (MLSM). The cellular uptake was shown to be dependent on the fatty-acid chain length, but no significant difference in the uptake of pyrene fatty acids was observed between MLSM and control lymphoid cells. After inc...

  5. Dependency of Tunneling-Magnetoresistance Ratio on Nanoscale Spacer Thickness and Material for Double MgO Based Perpendicular-Magnetic-Tunneling-Junction

    Science.gov (United States)

    Lee, Du-Yeong; Hong, Song-Hwa; Lee, Seung-Eun; Park, Jea-Gun

    2016-12-01

    It was found that in double MgO based perpendicular magnetic tunneling junction spin-valves ex-situ annealed at 400 °C, the tunneling magnetoresistance ratio was extremely sensitive to the material and thickness of the nanoscale spacer: it peaked at a specific thickness (0.40~0.53 nm), and the TMR ratio for W spacers (~134%) was higher than that for Ta spacers (~98%). This dependency on the spacer material and thickness was associated with the (100) body-centered-cubic crystallinity of the MgO layers: the strain enhanced diffusion length in the MgO layers of W atoms (~1.40 nm) was much shorter than that of Ta atoms (~2.85 nm) and the shorter diffusion length led to the MgO layers having better (100) body-centered-cubic crystallinity.

  6. Molecular analysis of fungal populations in patients with oral candidiasis using internal transcribed spacer region.

    Science.gov (United States)

    Ieda, Shinsuke; Moriyama, Masafumi; Takeshita, Toru; Takashita, Toru; Maehara, Takashi; Imabayashi, Yumi; Shinozaki, Shoichi; Tanaka, Akihiko; Hayashida, Jun-Nosuke; Furukawa, Sachiko; Ohta, Miho; Yamashita, Yoshihisa; Nakamura, Seiji

    2014-01-01

    Oral candidiasis is closely associated with changes in the oral fungal flora and is caused primarily by Candida albicans. Conventional methods of fungal culture are time-consuming and not always conclusive. However, molecular genetic analysis of internal transcribed spacer (ITS) regions of fungal rRNA is rapid, reproducible and simple to perform. In this study we examined the fungal flora in patients with oral candidiasis and investigated changes in the flora after antifungal treatment using length heterogeneity-polymerization chain reaction (LH-PCR) analysis of ITS regions. Fifty-two patients with pseudomembranous oral candidiasis (POC) and 30 healthy controls were included in the study. Fungal DNA from oral rinse was examined for fungal species diversity by LH-PCR. Fungal populations were quantified by real-time PCR and previously-unidentified signals were confirmed by nucleotide sequencing. Relationships between the oral fungal flora and treatment-resistant factors were also examined. POC patients showed significantly more fungal species and a greater density of fungi than control individuals. Sixteen fungi were newly identified. The fungal populations from both groups were composed predominantly of C. albicans, though the ratio of C. dubliniensis was significantly higher in POC patients than in controls. The diversity and density of fungi were significantly reduced after treatment. Furthermore, fungal diversity and the proportion of C. dubliniensis were positively correlated with treatment duration. These results suggest that C. dubliniensis and high fungal flora diversity might be involved in the pathogenesis of oral candidiasis. We therefore conclude that LH-PCR is a useful technique for diagnosing and assessing the severity of oral candidal infection.

  7. Gamma-irradiation of homodeoxyoligonucleotides 32P-labelled at one end: computer simulation of the chain length distribution of the radioactive fragments

    International Nuclear Information System (INIS)

    Teoule, R.; Duplaa, A.M.

    1987-01-01

    Electrophoresis on polyacrylamide gels of the fragments resulting from γ-irradiation of single-stranded oligodeoxyribonucleotides labelled at their 5'- or 3'-end proved a potent tool for analysis of the radiation-induced chain breakage of DNA. Owing to the fact that the oligonucleotide may be ruptured at more than one site, counting of the electrophoresis bands must be corrected and it is necessary to assess the influence of the cleavage position on the band intensities. A complicating factor is the inhomogeneity of the system due to the presence of the four bases A, T, C and G. To circumvent this problem, the homooligodeoxyribonucleotides (dA) 15 , (dC) 15 , (dT) 15 were used as experimental probes. They were γ-irradiated in solution, heated in alkali and resulting fragments separated by gel electrophoresis. A computer simulation of band intensities was compiled based on the general assumption that the chain breakage is homogeneous. Experimental results obtained from the homooligodeoxyribonucleotides labelled at either the 5' or the 3'-end are in excellent agreement with theoretical calculations. Abacus giving the gel band intensities (percentage) against the nucleotide positions and the remaining intensity of the original oligonucleotide have been obtained. (author)

  8. Fouling resilient perforated feed spacers for membrane filtration.

    Science.gov (United States)

    Kerdi, Sarah; Qamar, Adnan; Vrouwenvelder, Johannes S; Ghaffour, Noreddine

    2018-04-24

    The improvement of feed spacers with optimal geometry remains a key challenge for spiral-wound membrane systems in water treatment due to their impact on the hydrodynamic performance and fouling development. In this work, novel spacer designs are proposed by intrinsically modifying cylindrical filaments through perforations. Three symmetric perforated spacers (1-Hole, 2-Hole, and 3-Hole) were in-house 3D-printed and experimentally evaluated in terms of permeate flux, feed channel pressure drop and membrane fouling. Spacer performance is characterized and compared with standard no perforated (0-Hole) design under constant feed pressure and constant feed flow rate. Perforations in the spacer filaments resulted in significantly lowering the net pressure drop across the spacer filled channel. The 3-Hole spacer was found to have the lowest pressure drop (50%-61%) compared to 0-Hole spacer for various average flow velocities. Regarding permeate flux production, the 0-Hole spacer produced 5.7 L m -2 .h -1 and 6.6 L m -2 .h -1 steady state flux for constant pressure and constant feed flow rate, respectively. The 1-Hole spacer was found to be the most efficient among the perforated spacers with 75% and 23% increase in permeate production at constant pressure and constant feed flow, respectively. Furthermore, membrane surface of 1-Hole spacer was found to be cleanest in terms of fouling, contributing to maintain higher permeate flux production. Hydrodynamic understanding of these perforated spacers is also quantified by performing Direct Numerical Simulation (DNS). The performance enhancement of these perforated spacers is attributed to the formation of micro-jets in the spacer cell that aided in producing enough unsteadiness/turbulence to clean the membrane surface and mitigate fouling phenomena. In the case of 1-Hole spacer, the unsteadiness intensity at the outlet of micro-jets and the shear stress fluctuations created inside the cells are higher than those

  9. Nuclear reactor fuel assembly spacer grid

    International Nuclear Information System (INIS)

    Jabsen, F.S.

    1977-01-01

    A spacer grid for a nuclear fuel assembly is comprised of a lattice of grid plates forming multiple cells that are penetrated by fuel elements. Resilient protrusions and rigid protrusions projecting into the cells from the plates bear against the fuel element to effect proper support and spacing. Pairs of intersecting grid plates, disposed in a longitudinally spaced relationship, cooperate with other plates to form a lattice wherein each cell contains adjacent panels having resilient protrusions arranged opposite adjacent panels having rigid protrusions. The peripheral band bounding the lattice is provided solely with rigid protrusions projecting into the peripheral cells. (Auth.)

  10. Influence of chain length of pyrene fatty acids on their uptake and metabolism by Epstein-Barr-virus-transformed lymphoid cell lines from a patient with multisystemic lipid storage myopathy and from control subjects.

    Science.gov (United States)

    Radom, J; Salvayre, R; Levade, T; Douste-Blazy, L

    1990-01-01

    The uptake and intracellular metabolism of 4-(1-pyrene)butanoic acid (P4), 10-(1-pyrene)decanoic acid (P10) and 12-(1-pyrene)dodecanoic acid (P12) were investigated in cultured lymphoid cell lines from normal individuals and from a patient with multisystemic lipid storage myopathy (MLSM). The cellular uptake was shown to be dependent on the fatty-acid chain length, but no significant difference in the uptake of pyrene fatty acids was observed between MLSM and control lymphoid cells. After incubation for 1 h the distribution of fluorescent fatty acids taken up by the lymphoid cell lines also differed with the chain length, most of the fluorescence being associated with phospholipid and triacylglycerols. In contrast with P10 and P12, P4 was not incorporated into neutral lipids. When the cells were incubated for 24 h with the pyrene fatty acids, the amount of fluorescent lipids synthesized by the cells was proportional to the fatty acid concentration in the culture medium. After a 24 h incubation in the presence of P10 or P12, at any concentration, the fluorescent triacylglycerol content of MLSM cells was 2-5-fold higher than that of control cells. Concentrations of pyrene fatty acids higher than 40 microM seemed to be more toxic for mutant cells than for control cells. This cytotoxicity was dependent on the fluorescent-fatty-acid chain length (P12 greater than P10 greater than P4). Pulse-chase experiments permitted one to demonstrate the defect in the degradation of endogenously biosynthesized triacylglycerols in MLSM cells (residual activity was around 10-25% of controls on the basis of half-lives and initial rates of P10- or P12-labelled-triacylglycerol catabolism); MLSM lymphoid cells exhibited a mild phenotypic expression of the lipid storage (less severe than that observed in fibroblasts). P4 was not utilized in the synthesis of triacylglycerols, and thus did not accumulate in MLSM cells: this suggests that natural short-chain fatty acids might induce a lesser

  11. Identification of forensically important Chrysomya (Diptera: Calliphoridae) species using the second ribosomal internal transcribed spacer (ITS2).

    Science.gov (United States)

    Nelson, Leigh A; Wallman, James F; Dowton, Mark

    2008-05-20

    The identification of forensically important blowflies of the genus Chrysomya (Diptera: Calliphoridae) may be hampered by their close morphological similarities, especially as immatures. In contrast to most previous studies, the utility of a nuclear rather than mitochondrial genetic marker was investigated to solve this problem. The second internal transcribed spacer (ITS2) of ribosomal DNA (rDNA) was amplified and sequenced from all nine Chrysomya species known from Australia. Difficulties encountered with direct sequencing of ITS2 for Chrysomya flavifrons necessitated cloning prior to sequencing for this species, which revealed a low level (0-0.23%) of intraindividual variation. Five restriction enzymes (DraI, BsaXI, BciVI, AseI and HinfI) were identified that were able to differentiate most members of the genus by polymerase chain reaction (PCR) restriction fragment length polymorphism (PCR-RFLP). The PCR-RFLP analysis revealed characteristic restriction profiles for all species except the closely related species pairs Chrysomya latifrons+Chrysomya semimetallica and Chrysomya incisuralis+Chrysomya rufifacies. Ch. incisuralis and Ch. rufifacies were able to be separated using the size differences resulting from amplification of the entire ITS region. The lack of intraspecific ITS2 sequence variation among eight Ch. incisuralis specimens was verified by the identical restriction profiles generated from these specimens. A DNA-based approach, such as PCR-RFLP, has the capacity to be useful for the identification of forensic entomological evidence in cases where morphological characters are unreliable.

  12. Nuclear reactor spring strip grid spacer

    International Nuclear Information System (INIS)

    Patterson, J.F.; Flora, B.S.

    1978-01-01

    A bimetallic grid spacer is described comprising a grid structure of zircaloy formed by intersecting striplike members which define fuel element openings for receiving fuel elements and spring strips made of Inconel positioned within the grid structure for cooperating with the fuel elements to maintain them in their desired position. A plurality of these spring strips extend longitudinally between sides of the grid structure, being locked in position by the grid retaining strips. The fuel rods, which are disposed in the fuel openings formed in the grid structure, are positioned by means of the springs associated with the spring strips and a plurality of dimples which extend from the zircaloy grid structure into the openings. In one embodiment the strips are disposed in a plurality of arrays with those spring strip arrays situated in opposing diagonal quadrants of the grid structure extending in the same direction and adjacent spring strip arrays in each half of the spacer extending in relatively perpendicular directions. Other variations of the spring strip arrangements for a particular fuel design are disclosed herein

  13. Spacers for use in nuclear fuel assembly

    International Nuclear Information System (INIS)

    Shiohata, Hironori; Nakamura, Shozo; Hasegawa, Kunio; Higuchi, Shigeo; Nagashima, Hideaki; Kawada, Yoshishige.

    1987-01-01

    Purpose: To prevent liquid film breakage at the surface of a fuel rod due to swirlings of steam flow generated at the upstream of a contact portion between the fuel rod and a spacer leaf spring, that is, below the contact portion. Constitution: Steam-hot water 2-phase streams flowing from the lower to the upper portions of a fuel assembly is hindered by leaf springs, thereby forming swirlings in the steam flow at the upstream of a contact portion between the fuel rod and the leaf springs, that is, below the contact portion. The horseshoe-like swirlings shed the liquid films at the surface of the fuel rod to remarkably decrease the heat cooling performance, by which the surface temperature of a fuel can is temporarily increased thereby possibly causing failures due to so-called burnout in view of the above, steps are formed to the spacer leaf spring for use in the fuel assembly, to reduce the pressure difference between the leaf spring and the fuel rod at the upstream of the springs relative to the 2-phase coolant stream. In this way, formation of the swirlings is moderated to prevent the liquid film breakage and improve the critical heat power. (Kamimura, M.)

  14. Development of structural technology for a high performance spacer grid

    International Nuclear Information System (INIS)

    Song, Kee Nam; Kim, H. K.; Kang, H. S.

    2003-03-01

    A spacer grid in a LWR fuel assembly is a key structural component to support fuel rods and to enhance the heat transfer from the fuel rod to the coolant. In this research, the main research items are the development of inherent and high performance spacer grid shapes, the establishment of mechanical/structural analysis and test technology, and the set-up of basic test facilities for the spacer grid. The main research areas and results are as follows. 1. 14 different spacer grid candidates have been invented and applied for domestic and US patents. Among the candidates six are chosen from the patent. 2. Two kinds of spacer grids are finally selected for the advanced LWR fuel after detailed performance tests on the candidates and commercial spacer grids from a mechanical/structural point of view. According to the test results the features of the selected spacer grids are better than those of the commercial spacer grids. 3. Four kinds of basic test facilities are set up and the relevant test technologies are established. 4. Mechanical/structural analysis models and technology for spacer grid performance are developed and the analysis results are compared with the test results to enhance the reliability of the models

  15. Pressure Drop of Chamfer on Spacer Grid Strap

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Euijae; Kim, Kanghoon; Kim, Kyounghong; Nahm, Keeyil [KEPCO Nuclear Fuel Co., Daejeon (Korea, Republic of)

    2014-05-15

    A swirl flow and cross flow are generated by the spacer grid with mixing vane that enhances the thermal performance and critical heat flux (CHF). The additional pressure drop makes it difficult to meet acceptance criteria for overall pressure drop in fuel assembly depending upon the pump capacity. The chamfer on the end of spacer grid strap is one solution to reduce additional pressure drop without any adverse effect on flow fields. In this research, the pressure drop tests for spacer grid with and without chamfer were carried out at the hydraulic test facility. The result can be applied to develop high performance nuclear fuel assemblies for Pressurized Water Reactor (PWR) plants. The pressure drop tests for 5x5 spacer grid with and without chamfer as well as 6x6 spacer grid with and without chamfer were carried out at the INFINIT test facility. The Reynolds number ranged about from 16000 to 75000. The sweep-up and sweep-down test showed that the direction of sweep did not affect the pressure drop. The chamfer on spacer grid strap reduced the pressure drop due to the decreased in ratio of inlet area to outlet area. The pressure loss coefficient for spacer grid with chamfer was by up to 13.8 % lower than that for spacer grid without chamfer. Hence, the chamfer on spacer grid strap was one of effective ways to reduce the pressure drop.

  16. Finite element analysis of the contact between fuel rod and spacer grid

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyung Kyu; Kim, Young Koon; Kang, Heung Seok; Yoon, Kyung Ho; Song, Kee Nam [Korea Atomic Energy Research Institute, Taejon (Korea)

    1999-01-01

    For the research on the fretting failure problem of nuclear fuel, the contact length and normal stress field are evaluated for the contact between fuel rod and spacer grid by using the Finite Element Method (FEM). An assumption of semi-infiniteness is necessary for applying the Contact Mechanics which is based on the classical theory of elasticity to the present problem. For the contact problem of fuel fretting, the contact mechanical solutions could be utilized well with sufficient accuracy if the contact bodies (i.e., the cladding tube and the spacer grid) can be assumed as semi-infinite bodies. To this end, the contact length evaluated by FEM is discussed together with the relevant research which concerned the effect of dimension for the validity of the assumption of semi-infiniteness. Normal stress profile on the contact is also studied through comparing the theoretical and the FE results. For the analysis of contact problem by FEM, ANSYS code (Version 5.3) is utilized and the geometry is chosen to be the Hertzian (cylinder-to-cylinder), the strip-to-cylinder and the fuel rod/spacer grid contact (strip-to-tube). Present research will be utilized for accessing the fuel fretting problem by FEM together with the theoretical (i.e., contact mechanical) analysis which has been published as KAERI/TR-1113/98. (author). 15 refs., 44 figs., 4 tabs.

  17. Engineering a disulfide bond in the lid hinge region of Rhizopus chinensis lipase: increased thermostability and altered acyl chain length specificity.

    Directory of Open Access Journals (Sweden)

    Xiao-Wei Yu

    Full Text Available The key to enzyme function is the maintenance of an appropriate balance between molecular stability and structural flexibility. The lid domain which is very important for "interfacial activation" is the most flexible part in the lipase structure. In this work, rational design was applied to explore the relationship between lid rigidity and lipase activity by introducing a disulfide bond in the hinge region of the lid, in the hope of improving the thermostability of R. chinensis lipase through stabilization of the lid domain without interfering with its catalytic performance. A disulfide bridge between F95C and F214C was introduced into the lipase from R. chinensis in the hinge region of the lid according to the prediction of the "Disulfide by Design" algorithm. The disulfide variant showed substantially improved thermostability with an eleven-fold increase in the t(1/2 value at 60°C and a 7°C increase of T(m compared with the parent enzyme, probably contributed by the stabilization of the geometric structure of the lid region. The additional disulfide bond did not interfere with the catalytic rate (k(cat and the catalytic efficiency towards the short-chain fatty acid substrate, however, the catalytic efficiency of the disulfide variant towards pNPP decreased by 1.5-fold probably due to the block of the hydrophobic substrate channel by the disulfide bond. Furthermore, in the synthesis of fatty acid methyl esters, the maximum conversion rate by RCLCYS reached 95% which was 9% higher than that by RCL. This is the first report on improving the thermostability of the lipase from R. chinensis by introduction of a disulfide bond in the lid hinge region without compromising the catalytic rate.

  18. Dynamics of cyanophenyl alkylbenzoate molecules in the bulk and in a surface layer adsorbed onto aerosil. Variation of the lengths of the alkyl chain

    Energy Technology Data Exchange (ETDEWEB)

    Frunza, Stefan [National Institute of Materials Physics, R-077125 Magurele (Romania); Schoenhals, Andreas [BAM Federal Institute of Materials Research and Testing, D-12205 Berlin (Germany); Frunza, Ligia, E-mail: lfrunza@infim.ro [National Institute of Materials Physics, R-077125 Magurele (Romania); Beica, Traian; Zgura, Irina; Ganea, Paul [National Institute of Materials Physics, R-077125 Magurele (Romania); Stoenescu, Daniel [Telecom-Bretagne, Departement d' Optique, Technopole Brest-Iroise 29238 Cedex (France)

    2010-06-16

    Graphical abstract: The temperature dependence of the molecular mobility in composites shows an Arrhenius-type regime at low temperature and a glassy-type one at higher temperature separated by a crossover phenomenon. - Abstract: The molecular mobility of 4-butyl- and 4-pentyl-4'-cyanophenyl benzoate (CP4B, CP5B) and their composites prepared from aerosil A380 was investigated by broadband dielectric spectroscopy in a large temperature range. Thermogravimetric and infrared investigations were additionally performed. High silica density (larger than 7 g aerosil/1 g of liquid crystal) was selected to observe a thin layer adsorbed on the surface of the silica particles. The data were compared with those of the member of the series with six carbon atoms in the alkyl tail. Bulk CP4B and CP5B show the dielectric behaviour expected for liquid crystals. For the composites one relaxation process is observed at frequencies much lower than those for the corresponding bulk, which was assigned to the dynamics of the molecules in a surface layer. The temperature dependence of the relaxation rates (and of the dielectric strength) shows a crossover behaviour with two distinguished regimes. At higher temperatures the data obey the Vogel-Fulcher-Tammann law, whereas an Arrhenius law is observed at lower temperature, in a close similarity to the behaviour of a constrained dynamic glass transition. The estimated Vogel and crossover temperature is independent on the tail length, while the activation energy for the low temperature branch increases weakly with increasing the alkyl tail.

  19. Efficient thermal diode with ballistic spacer

    Science.gov (United States)

    Chen, Shunda; Donadio, Davide; Benenti, Giuliano; Casati, Giulio

    2018-03-01

    Thermal rectification is of importance not only for fundamental physics, but also for potential applications in thermal manipulations and thermal management. However, thermal rectification effect usually decays rapidly with system size. Here, we show that a mass-graded system, with two diffusive leads separated by a ballistic spacer, can exhibit large thermal rectification effect, with the rectification factor independent of system size. The underlying mechanism is explained in terms of the effective size-independent thermal gradient and the match or mismatch of the phonon bands. We also show the robustness of the thermal diode upon variation of the model's parameters. Our finding suggests a promising way for designing realistic efficient thermal diodes.

  20. Nuclear reactor spring strip grid spacer

    International Nuclear Information System (INIS)

    Patterson, J.F.; Flora, B.S.

    1980-01-01

    An improved and novel grid spacer was developed for use in nuclear reactor fuel assemblies. It is comprised of a series of intersecting support strips and a peripheral support band attached to the ends of the support strips. Each of the openings into which the fuel element is inserted has a number of protruding dimples and springs extending in different directions. The dimples coact with the springs to secure the fuel rods in the openings. Compared with previous designs, this design gives more positive alignment of the support stips while allowing greater flexibility to counterbalance the effects of thermal expansion. The springs are arranged in alternating directions so that the reaction forces tend to counterbalance each other, which in turn minimizes the reaction loads on the supporting structure. (D.N.)

  1. Custom-made hinged spacers in revision knee surgery for patients with infection, bone loss and instability.

    Science.gov (United States)

    Macmull, S; Bartlett, W; Miles, J; Blunn, G W; Pollock, R C; Carrington, R W J; Skinner, J A; Cannon, S R; Briggs, T W R

    2010-12-01

    Polymethyl methacrylate spacers are commonly used during staged revision knee arthroplasty for infection. In cases with extensive bone loss and ligament instability, such spacers may not preserve limb length, joint stability and motion. We report a retrospective case series of 19 consecutive patients using a custom-made cobalt chrome hinged spacer with antibiotic-loaded cement. The "SMILES spacer" was used at first-stage revision knee arthroplasty for chronic infection associated with a significant bone loss due to failed revision total knee replacement in 11 patients (58%), tumour endoprosthesis in four patients (21%), primary knee replacement in two patients (11%) and infected metalwork following fracture or osteotomy in a further two patients (11%). Mean follow-up was 38 months (range 24-70). In 12 (63%) patients, infection was eradicated, three patients (16%) had persistent infection and four (21%) developed further infection after initially successful second-stage surgery. Above knee amputation for persistent infection was performed in two patients. In this particularly difficult to treat population, the SMILES spacer two-stage technique has demonstrated encouraging results and presents an attractive alternative to arthrodesis or amputation. Copyright © 2009 Elsevier B.V. All rights reserved.

  2. PCR-Internal Transcribed Spacer (ITS) genes sequencing and ...

    African Journals Online (AJOL)

    Methods: DNA extraction, purification, amplification and sequencing of Internal Transcribed Spacer (ITS) genes were per- formed using ... Keywords: Internal transcribed spacer genes, phylogenetic, genetic relationship, clinical and environmental fungi, HIV-TB. ... Nigeria. An Ethical clearance was obtained from the Eth-.

  3. Stress Analysis of Single Spacer Grid Support considering Fuel Rod

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Y. G.; Jung, D. H.; Kim, J. H. [Chungnam National University, Daejeon (Korea, Republic of); Park, J. K.; Jeon, K. L. [Korea Nuclear Fuel, Daejeon (Korea, Republic of)

    2010-10-15

    Pressurized water reactor (PWR) nuclear fuel assembly is mainly composed of a top-end piece, a bottom-end piece, lots of fuel rods, and several spacer grids. Among them, the main function of spacer grid is protecting fuel rods from Fluid Induced Vibration (FIV). The cross section of spacer grid assembled by laser welding in upper and lower point. When the fuel rod inserted in spacer gird, spring and dimple and around of welded area got a stresses. The main hypothesis of this analysis is the boundary area of HAZ and base metal can get a lot of damage than other area by FIV. So, design factors of spacer grid mainly considered to preventing the fatigue failure in HAZ and spring and dimple of spacer grid. From previous researching, the environment in reactor verified. Pressure and temperature of light water observed 15MPa and 320 .deg. C, and vibration of the fuel rod observed within 0 {approx} 50Hz. In this study, mechanical properties of zirconium alloy that extracted from the test and the spacer grid model which used in the PWR were applied in stress analyzing. General-purpose finite element analysis program was used ANSYS Workbench 12.0.1 version. 3-D CAD program CATIA was used to create spacer grid model

  4. Mechanical/structural performance test method of a spacer grid

    International Nuclear Information System (INIS)

    Yoon, Kyung Ho

    2000-06-01

    The spacer grid is one of the main structural components in the fuel assembly, which supports the fuel rods, guides cooling water, and protects the system from an external impact load, such as earthquakes. In order to develop the spacer grid with the high mechanical performance, the mechanical and structural properties of the spacer grids must be extensively examined while designing it. In this report, the mechanical/structural test methods, i.e. the characteristic test of a spacer grid spring or dimple, static buckling test of a partial or full size spacer grid and dynamic impact test of them are described. The characteristic test of a spacer grid spring or dimple is accomplished with universal tensile test machine, a specimen is fixed with test fixture and then applied compressive load. The characteristic test data is saved at loading and unloading event. The static buckling test of a partial or full size spacer grid is executed with the same universal tensile testing machine, a specimen is fixed between cross-heads and then applied the compressive load. The buckling strength is decided the maximum strength at load vs. displacement curve. The dynamic impact test of a partial or full size spacer grid is performed with pendulum type impact machine and free fall shock test machine, a specimen is fixed with test fixture and then applied the impact load by impact hammer. Specially, the pendulum type impact test machine is also possible under the operating temperature because a furnace is separately attached with test machine

  5. ATLAS barrel hadron tile calorimeter: spacers plates mass production

    International Nuclear Information System (INIS)

    Artikov, A.M.; Budagov, Yu.A.; Khubua, J.

    1999-01-01

    In this article we expose the main problems of the mass production of the so-called 'spacer plates' for the ATLAS Barrel Hadron Tile Calorimeter. We describe all practical solutions of these problems. Particularly we present the measurement procedures and calculation schemes we used for the spacers dimensions determination. The results of the calculations are presented

  6. Genetic polymorphism of toll-like receptors 4 gene by polymerase chain reaction-restriction fragment length polymorphisms, polymerase chain reaction-single-strand conformational polymorphism to correlate with mastitic cows

    Directory of Open Access Journals (Sweden)

    Pooja H. Gupta

    2015-05-01

    Full Text Available Aim: An attempt has been made to study the toll-like receptors 4 (TLR4 gene polymorphism from cattle DNA to correlate with mastitis cows. Materials and Methods: In present investigation, two fragments of TLR4 gene named T4CRBR1 and T4CRBR2 of a 316 bp and 382 bp were amplified by polymerase chain reaction (PCR, respectively from Kankrej (22 and Triple cross (24 cattle. The genetic polymorphisms in the two populations were detected by a single-strand conformational polymorphism in the first locus and by digesting the fragments with restriction endonuclease Alu I in the second one. Results: Results showed that both alleles (A and B of two loci were found in all the two populations and the value of polymorphism information content indicated that these were highly polymorphic. Statistical results of χ2 test indicated that two polymorphism sites in the two populations fit with Hardy–Weinberg equilibrium (p˂0.05. Meanwhile, the effect of polymorphism of TLR4 gene on the somatic cell score (SCS indicated the cattle with allele a in T4CRBR1 showed lower SCS than that of allele B (p<0.05. Thus, the allele A might play an important role in mastitis resistance in cows. Conclusion: The relationship between the bovine mastitis trait and the polymorphism of TLR4 gene indicated that the bovine TLR4 gene may play an important role in mastitis resistance.

  7. CFD application to advanced design for high efficiency spacer grid

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, Kazuo, E-mail: kazuo3_ikeda@ndc.mhi.co.jp

    2014-11-15

    Highlights: • A new LDV was developed to investigate the local velocity in a rod bundle and inside a spacer grid. • The design information that utilizes for high efficiency spacer grid has been obtained. • CFD methodology that predicts flow field in a PWR fuel has been developed. • The high efficiency spacer grid was designed using the CFD methodology. - Abstract: Pressurized water reactor (PWR) fuels have been developed to meet the needs of the market. A spacer grid is a key component to improve thermal hydraulic performance of a PWR fuel assembly. Mixing structures (vanes) of a spacer grid promote coolant mixing and enhance heat removal from fuel rods. A larger mixing vane would improve mixing effect, which would increase the departure from nucleate boiling (DNB) benefit for fuel. However, the increased pressure loss at large mixing vanes would reduce the coolant flow at the mixed fuel core, which would reduce the DNB margin. The solution is to develop a spacer grid whose pressure loss is equal to or less than the current spacer grid and that has higher critical heat flux (CHF) performance. For this reason, a requirement of design tool for predicting the pressure loss and CHF performance of spacer grids has been increased. The author and co-workers have been worked for development of high efficiency spacer grid using Computational Fluid Dynamics (CFD) for nearly 20 years. A new laser Doppler velocimetry (LDV), which is miniaturized with fiber optics embedded in a fuel cladding, was developed to investigate the local velocity profile in a rod bundle and inside a spacer grid. The rod-embedded fiber LDV (rod LDV) can be inserted in an arbitrary grid cell instead of a fuel rod, and has the advantage of not disturbing the flow field since it is the same shape as a fuel rod. The probe volume of the rod LDV is small enough to measure spatial velocity profile in a rod gap and inside a spacer grid. According to benchmark experiments such as flow velocity

  8. CFD application to advanced design for high efficiency spacer grid

    International Nuclear Information System (INIS)

    Ikeda, Kazuo

    2014-01-01

    Highlights: • A new LDV was developed to investigate the local velocity in a rod bundle and inside a spacer grid. • The design information that utilizes for high efficiency spacer grid has been obtained. • CFD methodology that predicts flow field in a PWR fuel has been developed. • The high efficiency spacer grid was designed using the CFD methodology. - Abstract: Pressurized water reactor (PWR) fuels have been developed to meet the needs of the market. A spacer grid is a key component to improve thermal hydraulic performance of a PWR fuel assembly. Mixing structures (vanes) of a spacer grid promote coolant mixing and enhance heat removal from fuel rods. A larger mixing vane would improve mixing effect, which would increase the departure from nucleate boiling (DNB) benefit for fuel. However, the increased pressure loss at large mixing vanes would reduce the coolant flow at the mixed fuel core, which would reduce the DNB margin. The solution is to develop a spacer grid whose pressure loss is equal to or less than the current spacer grid and that has higher critical heat flux (CHF) performance. For this reason, a requirement of design tool for predicting the pressure loss and CHF performance of spacer grids has been increased. The author and co-workers have been worked for development of high efficiency spacer grid using Computational Fluid Dynamics (CFD) for nearly 20 years. A new laser Doppler velocimetry (LDV), which is miniaturized with fiber optics embedded in a fuel cladding, was developed to investigate the local velocity profile in a rod bundle and inside a spacer grid. The rod-embedded fiber LDV (rod LDV) can be inserted in an arbitrary grid cell instead of a fuel rod, and has the advantage of not disturbing the flow field since it is the same shape as a fuel rod. The probe volume of the rod LDV is small enough to measure spatial velocity profile in a rod gap and inside a spacer grid. According to benchmark experiments such as flow velocity

  9. A non-electrostatic spacer for aerosol delivery

    DEFF Research Database (Denmark)

    Bisgaard, H; Anhøj, J; Klug, B

    1995-01-01

    to 6 years, suspected to have asthma the non-electrostatic spacer delivered a mean total dose of budesonide aerosol of 39% of the nominal dose, which was significantly higher than the Babyhaler (28%), the Nebuhaler (21%), and the AeroChamber (19%). These differences were most pronounced in children......A pear shaped non-electrostatic spacer, composed of steel with a volume of 250 ml and equipped with a facemask containing integrated inlet and outlet valves for inspiration and expiration, was compared with three plastic spacers. The plastic spacers were primed with repeated puffs from a budesonide...... was 27 seconds and independent of the use of p-MDI. In vitro the maximum dose of budesonide from a p-MDI, expressed as a percentage of the nominal dose, was 56% from the non-electrostatic spacer, 61% from the Nebuhaler, 45% from the Babyhaler, and 30% from the AeroChamber. In 124 children, age 6 months...

  10. Boosting the ambipolar performance of solution-processable polymer semiconductors via hybrid side-chain engineering.

    Science.gov (United States)

    Lee, Junghoon; Han, A-Reum; Yu, Hojeong; Shin, Tae Joo; Yang, Changduk; Oh, Joon Hak

    2013-06-26

    Ambipolar polymer semiconductors are highly suited for use in flexible, printable, and large-area electronics as they exhibit both n-type (electron-transporting) and p-type (hole-transporting) operations within a single layer. This allows for cost-effective fabrication of complementary circuits with high noise immunity and operational stability. Currently, the performance of ambipolar polymer semiconductors lags behind that of their unipolar counterparts. Here, we report on the side-chain engineering of conjugated, alternating electron donor-acceptor (D-A) polymers using diketopyrrolopyrrole-selenophene copolymers with hybrid siloxane-solubilizing groups (PTDPPSe-Si) to enhance ambipolar performance. The alkyl spacer length of the hybrid side chains was systematically tuned to boost ambipolar performance. The optimized three-dimensional (3-D) charge transport of PTDPPSe-Si with pentyl spacers yielded unprecedentedly high hole and electron mobilities of 8.84 and 4.34 cm(2) V(-1) s(-1), respectively. These results provide guidelines for the molecular design of semiconducting polymers with hybrid side chains.

  11. N-terminal fatty acylated His-dPhe-Arg-Trp-NH(2) tetrapeptides: influence of fatty acid chain length on potency and selectivity at the mouse melanocortin receptors and human melanocytes.

    Science.gov (United States)

    Todorovic, Aleksandar; Holder, Jerry Ryan; Bauzo, Rayna M; Scott, Joseph Walker; Kavanagh, Renny; Abdel-Malek, Zalfa; Haskell-Luevano, Carrie

    2005-05-05

    The melanocortin system is involved in the regulation of a diverse number of physiologically important pathways including pigmentation, feeding behavior, weight and energy homeostasis, inflammation, and sexual function. All the endogenous melanocortin agonist ligands possess the conserved His-Phe-Arg-Trp tetrapeptide sequence that is postulated to be important for melanocortin receptor molecular recognition and stimulation. Previous studies by our laboratory resulted in the discovery that increasing alkyl chain length at the N-terminal "capping" region of the His-dPhe-Arg-Trp-NH(2) tetrapeptide resulted in a 100-fold increased melanocortin receptor agonist potency. This study was undertaken to systematically evaluate the pharmacological effects of increasing N-capping alkyl chain length of the CH(3)(CH(2))(n)CO-His-dPhe-Arg-Trp-NH(2) (n = 6-16) tetrapeptide template. Twelve analogues were synthesized and pharmacologically characterized at the mouse melanocortin receptors MC1R and MC3R-MC5R and human melanocytes known to express the MC1R. These peptides demonstrated melanocortin receptor selectivity profiles different from those of previously published tetrapeptides. The most notable results of enhanced ligand potency (20- to 200-fold) and receptor selectivity were observed at the MC1R. Tetrapeptides that possessed greater than nine alkyl groups were superior to alpha-MSH in terms of the stimulation of human melanocyte tyrosinase activity. Additionally, the n-pentadecanoyl derivative had a residual effect on tyrosinase activity that existed for at least 4 days after the peptide was removed from the human melanocyte culture medium. These data demonstrate the utility, potency, and residual effect of melanocortin tetrapeptides by adding N-terminal fatty acid moieties.

  12. Dansyl-naphthalimide dyads as molecular probes: effect of spacer group on metal ion binding properties.

    Science.gov (United States)

    Shankar, Balaraman H; Ramaiah, Danaboyina

    2011-11-17

    Interaction of a few dansyl-naphthalimide conjugates 1a-e linked through polymethylene spacer groups with various metal ions was investigated through absorption, fluorescence, NMR, isothermal calorimetric (ITC), and laser flash photolysis techniques. The characteristic feature of these dyads is that they exhibit competing singlet-singlet energy transfer (SSET) and photoinduced electron transfer (PET) processes, both of which decrease with the increase in spacer length. Depending on the spacer group, these dyads interact selectively with divalent Cu(2+) and Zn(2+) ions, as compared to other mono- and divalent metal ions. Jobs plot analysis showed that these dyads form 2:3 complexes with Cu(2+) ions, while 1:1 complexes were observed with Zn(2+) ions. The association constants for the Zn(2+) and Cu(2+) complexes were determined and are found to be in the order 10(3)-10(5) M(-1). Irrespective of the length of the spacer group, these dyads interestingly act as fluorescence ratiometric molecular probes for Cu(2+) ions by altering the emission intensity of both dansyl and naphthalimide chromophores. In contrast, only the fluorescence intensity of the naphthalimide chromophore of the lower homologues (n = 1-3) was altered by Zn(2+) ions. (1)H NMR and ITC measurements confirmed the involvement of both sulfonamide and dimethylamine groups in the complexation with Cu(2+) ions, while only the latter group was involved with Zn(2+) ions. Laser excitation of the dyads 1a-e showed formation of a transient absorption which can be attributed to the radical cation of the naphthalimide chromophore, whereas only the triplet excited state of the dyads 1a-e was observed in the presence of Cu(2+) ions. Uniquely, the complexation of 1a-e with Cu(2+) ions affects both PET and SSET processes, while only the PET process was partially inhibited by Zn(2+) ions in the lower homologues (n = 1-3) and the higher homologues exhibited negligible changes in their emission properties. Our results

  13. Maternal long chain polyunsaturated fatty acid supplementation in infancy increases length- and weight-for-age but not BMI to 6 years when controlling for effects of maternal smoking

    Science.gov (United States)

    Currie, L.M.; Tolley, E.A.; Thodosoff, J.M.; Kerling, E.H.; Sullivan, D.K.; Colombo, J.; Carlson, S.E.

    2015-01-01

    Summary Long chain polyunsaturated fatty acids (LCPUFA) are added to infant formula but their effect on long-term growth of children is under studied. We evaluated the effects of feeding LCPUFA-supplemented formula (n=54) compared to control formula (n=15) throughout infancy on growth from birth-6 years. Growth was described using separate models developed with the MIXED procedure of SAS® that included maternal smoking history and gender. Compared to children fed control formula, children who consumed LCPUFA supplemented formula had higher length-/stature-/and weight-for-age percentiles but not body mass index (BMI) percentile from birth to 6 years. Maternal smoking predicted lower stature (2-6 years), higher weight-for-length (birth-18 months) and BMI percentile (2-6 years) independent of LCPUFA effects. Gender interacted with the effect of LCPUFA on stature, and the relationship between smoking and BMI, with a larger effect for boys. Energy intake did not explain growth differences. A relatively small control sample is a limitation. PMID:25936840

  14. Preclinical investigations towards the first spacer gel application in prostate cancer treatment during particle therapy at HIT

    International Nuclear Information System (INIS)

    Ruciński, Antoni; Parodi, Katia; Jäkel, Oliver; Haberer, Thomas; Bauer, Julia; Campbell, Patrick; Brons, Stephan; Unholtz, Daniel; Habl, Gregor; Herfarth, Klaus; Debus, Jürgen; Bert, Christoph

    2013-01-01

    The application of spacer gel represents a promising approach to reliably spare the rectal frontal wall during particle therapy (IJROBP 76:1251-1258, 2010). In order to qualify the spacer gel for the clinical use in particle therapy, a variety of measurements were performed in order to ensure the biological compatibility of the gel, its physical stability during and after the irradiation, and a proper definition of the gel in terms of the Hounsfield Unit (HU) values for the treatment planning system. The potential for the use of the spacer gel for particle therapy monitoring with off-line Positron Emission Tomography (PET) was also investigated. The spacer gel implanted to the prostate patient in direct neighbourhood to the clinical target volume does not interfere with the particle therapy treatment planning procedure applied at Heidelberg Ion Beam Therapy Centre (HIT). The performed measurements show that Bragg-peak position of the particles can be properly predicted on the basis of computed tomography imaging with the treatment planning system used at HIT (measured water equivalent path length of 1.011 ±0.011 (2σ), measured Hounsfield Unit of 28.9 ±6.1 (2σ)). The spacer gel samples remain physically unchanged after irradiation with a dose exceeding the therapeutic dose level. The independently measured Bragg-Peak position does not change within the time interval of 10 weeks. As a result of the presented experiments, the first clinical application of spacer gel implant during prostate cancer treatment with carbon ions and protons was possible at HIT in 2012. The reported pre-clinical investigations demonstrate that use of spacer gel is safe in particle therapy in presence of therapy target motion and patient positioning induced particle range variations. The spacer gel injected between prostate and rectum enlarge the distance between both organs, which is expected to clinically significantly decrease the undesirable exposure of the most critical organ at risk

  15. Fundamental length and relativistic length

    International Nuclear Information System (INIS)

    Strel'tsov, V.N.

    1988-01-01

    It si noted that the introduction of fundamental length contradicts the conventional representations concerning the contraction of the longitudinal size of fast-moving objects. The use of the concept of relativistic length and the following ''elongation formula'' permits one to solve this problem

  16. Procedure for vibration test of the fuel rod supported by spacer grids

    International Nuclear Information System (INIS)

    Choi, Myoung Hwan; Kang, Heung Seok; Yoon, Kyung Ho; Kim, Hyung Kyu; Song, Kee Nam

    2002-07-01

    One of the methods that are used to compare and verify the supporting performance of the spacer grids developed is the vibration characteristic test. In this report there are two aims. One is of the understand of the experimental method and procedure performing the modal testing using I-DEAS TDAS module. The other is the investigation of the vibration behaviors of a dummy fuel rod supported by 8 optimized H type spacer grids. This report describes the method and procedure of modal testing to obtain the vibration characteristics such as amplitudes, natural frequencies and mode shapes of the fuel rod using a shaker, a non-contact gap sensor and an accelerometer. This report provides a test procedure in detail so that anyone can be easily understood and use the I-DEAS TDAS program. The I-DEAS TDAS program related to the modal testing has several tasks including the Modal analysis, Signal Processing et al.. This report includes model preparation to prepare the geometrical model, Signal Processing (Sine/Standard measurement) to acquire the signal, Modal analysis to obtain the frequencies and mode shapes, Correlation to analyze the relation between the test and FE analysis and Post Processing tasks. In addition, this report contains the actual test and analysis data of a dummy fuel rod in length 3847mm supported by 8 optimized H type spacer grids

  17. [Identification of medicinal plant Dendrobium based on the chloroplast psbK-psbI intergenic spacer].

    Science.gov (United States)

    Yao, Hui; Yang, Pei; Zhou, Hong; Ma, Shuang-jiao; Song, Jing-yuan; Chen, Shi-lin

    2015-06-01

    In this paper, the chloroplast psbK-psbI intergenic spacers of 18 species of Dendrobium and their adulterants were amplified and sequenced, and then the sequence characteristics were analyzed. The sequence lengths of chloroplast psbK-psbI regions of Dendrobium ranged from 474 to 513 bp and the GC contents were 25.4%-27.6%. The variable sites were 71 while the informative sites were 46. The inter-specific genetic distances calculated by Kimura 2-parameter (K2P) of Dendrobium were 0.006 1-0.058 1, with an average of 0.028 4. The K2P genetic distances between Dendrobium species and Bulbophyllum odoratissimum were 0.093 2-0.120 4. The NJ tree showed that the Dendrobium species can be easily differentiated from each other and 6 samples of the inspected Dendrobium species were identified successfully through sequencing the psbK-psbI intergenic spacer. Therefore, the chloroplast psbK-psbI intergenic spacer can be used as a candidate marker to identify Dendrobium species and its adulterants.

  18. Flame Length

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — Flame length was modeled using FlamMap, an interagency fire behavior mapping and analysis program that computes potential fire behavior characteristics. The tool...

  19. Effects of different rod spacers (helical types) on coolant crossmixing

    International Nuclear Information System (INIS)

    Zhukov, A.V.; Sviridenko, E.Ya.; Matyukhin, N.M.; Rymkevich, K.S.; Ushakov, P.A.

    1981-11-01

    The results of investigations (electromagnetic measuring method) on coolant cross mixing in rod clusters with spiral wire spacers with different winding directions, with alternating unfinned and finned rods (case 'fin to rod'), as well as in rod clusters with much space between the rods, (case 'fin to fin') are reported. The local fluid dynamics parameters (distribution of the transversal and longitudinal velocity component) that define the physical processes of the coolant exchange in the rod clusters with helical spacers are explained. The investigation results for different helical spacer types are compared with each other. (orig.) [de

  20. Grid spacers for use in a nuclear fuel assembly

    International Nuclear Information System (INIS)

    Kuwako, Akira.

    1987-01-01

    Purpose: To obtain spacers capable of reducing the pressure loss by enlarging coolant flow channels when the fuel temperature is high, while capable of reliably maintaining the fuel pins with no vibrations when the fuel temperature is low. Constitution: This invention concerns grid spacers for constituting fuel assemblies for use in water cooled reactors. Memory shape alloys are disposed at least a portion of a spacer element that takes such a shape as urging the pin when the fuel temperature is low, while enlarging the coolant flow channel to reduce the pressure loss when the fuel temperature is high. (Ikeda, J.)

  1. Preclinical Evaluation of Bioabsorbable Polyglycolic Acid Spacer for Particle Therapy

    International Nuclear Information System (INIS)

    Akasaka, Hiroaki; Sasaki, Ryohei; Miyawaki, Daisuke; Mukumoto, Naritoshi; Sulaiman, Nor Shazrina Binti; Nagata, Masaaki; Yamada, Shigeru; Murakami, Masao; Demizu, Yusuke; Fukumoto, Takumi

    2014-01-01

    Purpose: To evaluate the efficacy and safety of a polyglycolic acid (PGA) spacer through physical and animal experiments. Methods and Materials: The spacer was produced with surgical suture material made of PGA, forming a 3-dimensional nonwoven fabric. For evaluation or physical experiments, 150-MeV proton or 320-MeV carbon-ion beams were used to generate 60-mm width of spread-out Bragg peak. For animal experiments, the abdomens of C57BL/6 mice, with or without the inserted PGA spacers, were irradiated with 20 Gy of carbon-ion beam (290 MeV) using the spread-out Bragg peak. Body weight changes over time were scored, and radiation damage to the intestine was investigated using hematoxylin and eosin stain. Blood samples were also evaluated 24 days after the irradiation. Long-term thickness retention and safety were evaluated using crab-eating macaques. Results: No chemical or structural changes after 100 Gy of proton or carbon-ion irradiation were observed in the PGA spacer. Water equivalency of the PGA spacer was equal to the water thickness under wet condition. During 24 days' observation after 20 Gy of carbon-ion irradiation, the body weights of mice with the PGA spacer were relatively unchanged, whereas significant weight loss was observed in those mice without the PGA spacer (P<.05). In mice with the PGA spacer, villus and crypt structure were preserved after irradiation. No inflammatory reactions or liver or renal dysfunctions due to placement of the PGA spacer were observed. In the abdomen of crab-eating macaques, thickness of the PGA spacer was maintained 8 weeks after placement. Conclusions: The absorbable PGA spacer had water-equivalent, bio-compatible, and thickness-retaining properties. Although further evaluation is warranted in a clinical setting, the PGA spacer may be effective to stop proton or carbon-ion beams and to separate normal tissues from the radiation field

  2. Azobenzene side-chain liquid crystalline polyesters with outstanding optical storage properties

    DEFF Research Database (Denmark)

    Hvilsted, Søren; Pedersen, M; Holme, NCR

    1998-01-01

    A flexible azobenzene side-chain liquid crystalline (SCLC) polyester architecture employed for reversible optical storage is described. The modular design allows four structural parameters to be individually modified. These parameters: i- the methylene side-chain spacer length, ii- the substituent......,000 are routinely obtained by melt transesterification of the novel diols and selected diacid precursors (parameter iii). Prominent storage features include no prealignment of thin SCLC polyester films prior to the writing process, and sensitivity in a broad laser wavelength window (415-532 nm). Additionally...... sign of fatigue. The non-destructive read out is performed with red light (600-750 nm). Finally, erasing the information can be achieved by heating the polyester film to 80 degrees C or irradiating it briefly with UV-light. In the latter case at least 10,000 write, read and erase cycles are possible...

  3. Analysis of US patents on spacer grids

    International Nuclear Information System (INIS)

    Kim, Hyung Kyu; Song, Kee Nam; Yoon, Kyung Ho; Kang, Hong Seok; Kim, Hyung Kyu; Jeon, Tae Hyun; Oh, Dong Seok; In, Wang Ki; Bang, Jae Keun; Oh, Seung Eun; Seo, Jeong Min; Lee, Jin Seok; Park, Seong Keun

    1997-06-01

    The total of 137 US patents on spacer grids patented from 1968 through 1993 are analyzed and summarized. Database is constituted with designing the appropriate fields by which each patent can be identified. The fields consist of patent number, inventor, assignee, date of patent, title and major foci of the patent. The major foci are again classified by detailed subjects such as the fretting failure and fuel rod support-related, the strength-related, the fabrication-related as for mechanical subjects, while the cooling performance-related and the pressure drop-related as for thermal-hydraulic one. The 92% of the patents analyzed were issued form nuclear companies of USA, France and Germany. Among the patents dealing with mechanical subjects, the fretting failure and fuel rod support-related is more than the pressure drop-related among the patents of thermal-hydraulic subjects. The number of patents issued from Japan ranks just after Germany i.e., the 4th country. It is thought that much concern as well as investment should be increased in this field, the patent of nuclear components. (author). 2 tabs., 5 figs

  4. Analysis of US patents on spacer grids

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyung Kyu; Song, Kee Nam; Yoon, Kyung Ho; Kang, Hong Seok; Kim, Hyung Kyu; Jeon, Tae Hyun; Oh, Dong Seok; In, Wang Ki; Bang, Jae Keun [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of); Oh, Seung Eun; Seo, Jeong Min; Lee, Jin Seok; Park, Seong Keun [Korea Nuclear Fuel Company, Taejon (Korea, Republic of)

    1997-06-01

    The total of 137 US patents on spacer grids patented from 1968 through 1993 are analyzed and summarized. Database is constituted with designing the appropriate fields by which each patent can be identified. The fields consist of patent number, inventor, assignee, date of patent, title and major foci of the patent. The major foci are again classified by detailed subjects such as the fretting failure and fuel rod support-related, the strength-related, the fabrication-related as for mechanical subjects, while the cooling performance-related and the pressure drop-related as for thermal-hydraulic one. The 92% of the patents analyzed were issued form nuclear companies of USA, France and Germany. Among the patents dealing with mechanical subjects, the fretting failure and fuel rod support-related is more than the pressure drop-related among the patents of thermal-hydraulic subjects. The number of patents issued from Japan ranks just after Germany i.e., the 4th country. It is thought that much concern as well as investment should be increased in this field, the patent of nuclear components. (author). 2 tabs., 5 figs.

  5. Multivalent cyclic RGD ligands: influence of linker lengths on receptor binding

    Energy Technology Data Exchange (ETDEWEB)

    Kubas, Holger; Schaefer, Martin; Bauder-Wuest, Ulrike; Eder, Matthias; Oltmanns, Doerte [Department of Radiopharmaceutical Chemistry, German Cancer Research Center, Im Neuenheimer Feld 280, 69120 Heidelberg (Germany); Haberkorn, Uwe; Mier, Walter [Department of Nuclear Medicine, University Hospital Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg (Germany); Eisenhut, Michael, E-mail: m.eisenhut@dkfz.d [Department of Radiopharmaceutical Chemistry, German Cancer Research Center, Im Neuenheimer Feld 280, 69120 Heidelberg (Germany)

    2010-11-15

    Peptides involving the RGD motive (arginine-glycine-aspartic acid) recognize members of the integrin receptor family. Since the receptors are located mainly on the surface of endothelial cells, structural modifications including multimers of c(RGDfE) were recently found to improve the binding avidity for {alpha}{sub v{beta}3} integrin significantly. The multivalent RGD peptides exhibited rather loose linkages partly including oligo(ethylene glycol) spacers (EG{sub n}) with different chain lengths. Therefore, the dependence of multivalent RGD systems with and without EG{sub n} linkers were investigated on their binding properties to cultured {alpha}{sub v{beta}3} integrin-expressing U87MG cells. Methods: We synthesized a series of di-, tri- and tetravalent rigid scaffolds (terephthalic acid, trimesic acid and adamantane-1,3,5,7-tetracarboxylic acid) conjugated to c(RGDyK) ligands, which were linked contiguously or separated by the oligo(ethylene glycol) spacers. The inhibition constants of these c(RGDyK) derivatives were determined by competition assays with {sup 125}I-labeled echistatin. Results: While c(RGDyK) function is a relative weak competitor against [{sup 125}I]echistatin (K{sub i}, 329{+-}18 nM) for {alpha}{sub v{beta}3} integrin-expressing U87MG cells, RGD dimers improved the competition potency considerably (K{sub i}, 64{+-}23 nM). This effect was even more pronounced with the RGD trimers (K{sub i}, 40{+-}7 nM) and tetramers (K{sub i}, 26{+-}9 nM). The introduction of EG{sub n} spacers and the increase of linker lengths proved to be detrimental since more competitors were needed to compete with [{sup 125}I]echistatin. The EG{sub 6} group, for example, reduced the inhibition constants by 29% (dimer), 57% (trimer) and 97% (tetramer). Conclusion: The binding experiments performed with the three forms of multivalent RGD ligands indicate the weakening of competitive potency against [{sup 125}I]echistatin with the introduction of EG{sub n} spacers. This effect

  6. Analytical calculation of chain length in ferrofluids

    Indian Academy of Sciences (India)

    2Department of Mechanical Engineering, Tezpur University, Assam 784028, India. MS received 4 ... under an external magnetic field applied parallel to the slit containing the ... of competition between magnetic dipolar interaction and.

  7. USE OF ANTIBIOTIC CEMENT SPACERS/BEADS IN TREATMENT ...

    African Journals Online (AJOL)

    ABSTRACT. Background: Chronic musculoskeletal infection involving bone present a big challenge to orthopaedic surgeons. ... Current data has demonstrated that the use of .... Antibiotic spacers are effective and add value in the treament of ...

  8. Analytical prediction of fuel assembly spacer grid loss coefficient

    International Nuclear Information System (INIS)

    Lim, J. S.; Nam, K. I.; Park, S. K.; Kwon, J. T.; Park, W. J.

    2002-01-01

    The analytical prediction model of the fuel assembly spacer grid pressure loss coefficient has been studied. The pressure loss of gap between the test section wall and spacer grid was separated from the current model and the different friction drag coefficient on spacer straps from high Reynolds number region were used to low Reynolds number region. The analytical model has been verified based on the hydraulic pressure drop test results for the spacer grids of three types for 5x5, 16x16(or 17x17) arrays. The analytical model predicts the pressure loss coefficients obtained from test results within the maximum errors of 12% and 7% for 5x5 test bundle and full size bundle, respectively, at Reynolds number 500,000 of the core operating condition. This result shows that the analytical model can be used for research and design change of the nuclear fuel assembly

  9. Response of an electrostatic probe for a right cylindrical spacer

    DEFF Research Database (Denmark)

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

    1994-01-01

    During the last decade many experimental studies of surface charge phenomena have been undertaken employing right cylindrical spacers. Measurement of the surface charge was performed using small electrostatic field probes to scan across the dielectric surface. Charges are electrostatically induced...

  10. Orthognathic model surgery with LEGO key-spacer.

    Science.gov (United States)

    Tsang, Alfred Chee-Ching; Lee, Alfred Siu Hong; Li, Wai Keung

    2013-12-01

    A new technique of model surgery using LEGO plates as key-spacers is described. This technique requires less time to set up compared with the conventional plaster model method. It also retains the preoperative setup with the same set of models. Movement of the segments can be measured and examined in detail with LEGO key-spacers. Copyright © 2013 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  11. Bioinformatics analyses of Shigella CRISPR structure and spacer classification.

    Science.gov (United States)

    Wang, Pengfei; Zhang, Bing; Duan, Guangcai; Wang, Yingfang; Hong, Lijuan; Wang, Linlin; Guo, Xiangjiao; Xi, Yuanlin; Yang, Haiyan

    2016-03-01

    Clustered regularly interspaced short palindromic repeats (CRISPR) are inheritable genetic elements of a variety of archaea and bacteria and indicative of the bacterial ecological adaptation, conferring acquired immunity against invading foreign nucleic acids. Shigella is an important pathogen for anthroponosis. This study aimed to analyze the features of Shigella CRISPR structure and classify the spacers through bioinformatics approach. Among 107 Shigella, 434 CRISPR structure loci were identified with two to seven loci in different strains. CRISPR-Q1, CRISPR-Q4 and CRISPR-Q5 were widely distributed in Shigella strains. Comparison of the first and last repeats of CRISPR1, CRISPR2 and CRISPR3 revealed several base variants and different stem-loop structures. A total of 259 cas genes were found among these 107 Shigella strains. The cas gene deletions were discovered in 88 strains. However, there is one strain that does not contain cas gene. Intact clusters of cas genes were found in 19 strains. From comprehensive analysis of sequence signature and BLAST and CRISPRTarget score, the 708 spacers were classified into three subtypes: Type I, Type II and Type III. Of them, Type I spacer referred to those linked with one gene segment, Type II spacer linked with two or more different gene segments, and Type III spacer undefined. This study examined the diversity of CRISPR/cas system in Shigella strains, demonstrated the main features of CRISPR structure and spacer classification, which provided critical information for elucidation of the mechanisms of spacer formation and exploration of the role the spacers play in the function of the CRISPR/cas system.

  12. Buckling behavior analysis of spacer grid by lateral impact load

    International Nuclear Information System (INIS)

    Yoon, Kyung Ho; Kang, Heung Seok; Kim, Hyung Kyu; Song, Kee Nam

    2000-05-01

    The spacer grid is one of the main structural components in the fuel assembly, Which supports the fuel rods, guides cooling water, and protects the system from an external impact load, such as earthquakes. Therefore, the mechanical and structural properties of the spacer grids must be extensively examined while designing it. In this report, free fall type shock tests on the several kinds of the specimens of the spacer grids were also carried out in order to compare the results among the candidate grids. A free fall carriage on the specimen accomplishes the test. In addition to this, a finite element method for predicting the critical impact strength of the spacer grids is described. FE method on the buckling behavior of the spacer grids are performed for a various array of sizes of the grids considering that the spacer grid is an assembled structure with thin-walled plates and imposing proper boundary conditions by nonlinear dynamic impact analysis using ABAQUS/explicit code. The simulated results results also similarly predicted the local buckling phenomena and were found to give good correspondence with the shock test results

  13. Fundamental length

    International Nuclear Information System (INIS)

    Pradhan, T.

    1975-01-01

    The concept of fundamental length was first put forward by Heisenberg from purely dimensional reasons. From a study of the observed masses of the elementary particles known at that time, it is sumrised that this length should be of the order of magnitude 1 approximately 10 -13 cm. It was Heisenberg's belief that introduction of such a fundamental length would eliminate the divergence difficulties from relativistic quantum field theory by cutting off the high energy regions of the 'proper fields'. Since the divergence difficulties arise primarily due to infinite number of degrees of freedom, one simple remedy would be the introduction of a principle that limits these degrees of freedom by removing the effectiveness of the waves with a frequency exceeding a certain limit without destroying the relativistic invariance of the theory. The principle can be stated as follows: It is in principle impossible to invent an experiment of any kind that will permit a distintion between the positions of two particles at rest, the distance between which is below a certain limit. A more elegant way of introducing fundamental length into quantum theory is through commutation relations between two position operators. In quantum field theory such as quantum electrodynamics, it can be introduced through the commutation relation between two interpolating photon fields (vector potentials). (K.B.)

  14. The potential of standard and modified feed spacers for biofouling control

    KAUST Repository

    Araújo, Paula A.

    2012-06-01

    The impact of feed spacers on initial feed channel pressure (FCP) drop, FCP increase and biomass accumulation has been studied in membrane fouling simulators using feed spacers applied in commercially available nanofiltration and reverse osmosis spiral wound membrane modules. All spacers had a similar geometry.Our studies showed that biofouling was not prevented by (i) variation of spacer thickness, (ii) feed spacer orientation, (iii) feed spacer coating with silver, copper or gold and (iv) using a biostatic feed spacer. At constant feed flow, a lower FCP and FCP increase were observed for a thicker feed spacer. At constant linear flow velocity, roughly the same FCP development and biomass accumulation were found irrespective of the feed spacer thickness: hydrodynamics and substrate load were more important for development and impact of biofouling than the thickness of currently applied spacers. Use of biostatic and metal coated spacers were not effective for biofouling control. The same small reduction of biofouling rate was observed with copper and silver coated spacers as well as uncoated 45° rotated spacers.The studied modified spacers were not effective for biofouling prevention and control. The impact of biofouling on FCP increase was reduced significantly by a lower linear flow velocity, while spacer orientation and spacer thickness in membrane modules had a smaller but still significant effect. © 2012 Elsevier B.V.

  15. The potential of standard and modified feed spacers for biofouling control

    KAUST Repository

    Araú jo, Paula A.; Kruithof, Joop C.; van Loosdrecht, Mark C.M.; Vrouwenvelder, Johannes S.

    2012-01-01

    The impact of feed spacers on initial feed channel pressure (FCP) drop, FCP increase and biomass accumulation has been studied in membrane fouling simulators using feed spacers applied in commercially available nanofiltration and reverse osmosis spiral wound membrane modules. All spacers had a similar geometry.Our studies showed that biofouling was not prevented by (i) variation of spacer thickness, (ii) feed spacer orientation, (iii) feed spacer coating with silver, copper or gold and (iv) using a biostatic feed spacer. At constant feed flow, a lower FCP and FCP increase were observed for a thicker feed spacer. At constant linear flow velocity, roughly the same FCP development and biomass accumulation were found irrespective of the feed spacer thickness: hydrodynamics and substrate load were more important for development and impact of biofouling than the thickness of currently applied spacers. Use of biostatic and metal coated spacers were not effective for biofouling control. The same small reduction of biofouling rate was observed with copper and silver coated spacers as well as uncoated 45° rotated spacers.The studied modified spacers were not effective for biofouling prevention and control. The impact of biofouling on FCP increase was reduced significantly by a lower linear flow velocity, while spacer orientation and spacer thickness in membrane modules had a smaller but still significant effect. © 2012 Elsevier B.V.

  16. Differentiation of canine distemper virus isolates in fur animals from various vaccine strains by reverse transcription-polymerase chain reaction-restriction fragment length polymorphism according to phylogenetic relations in china

    Directory of Open Access Journals (Sweden)

    Zhao Jianjun

    2011-02-01

    Full Text Available Abstract In order to effectively identify the vaccine and field strains of Canine distemper virus (CDV, a new differential diagnostic test has been developed based on reverse transcription-polymerase chain reaction (RT-PCR and restriction fragment length polymorphism (RFLP. We selected an 829 bp fragment of the nucleoprotein (N gene of CDV. By RFLP analysis using BamHI, field isolates were distinguishable from the vaccine strains. Two fragments were obtained from the vaccine strains by RT-PCR-RFLP analysis while three were observed in the field strains. An 829 nucleotide region of the CDV N gene was analyzed in 19 CDV field strains isolated from minks, raccoon dogs and foxes in China between 2005 and 2007. The results suggest this method is precise, accurate and efficient. It was also determined that three different genotypes exist in CDV field strains in fur animal herds of the north of China, most of which belong to Asian type. Mutated field strains, JSY06-R1, JSY06-R2 and JDH07-F1 also exist in Northern China, but are most closely related to the standard virulent strain A75/17, designated in Arctic and America-2 genetype in the present study, respectively.

  17. Effect of alkyl chain length and temperature on the thermodynamic properties of ionic liquids 1-alkyl-3-methylimidazolium bromide in aqueous and non-aqueous solutions at different temperatures

    International Nuclear Information System (INIS)

    Sadeghi, Rahmat; Shekaari, Hemayat; Hosseini, Rahim

    2009-01-01

    The alkyl chain length of 1-alkyl-3-methylimidazolium bromide ([Rmim][Br], R = propyl (C 3 ), hexyl (C 6 ), heptyl (C 7 ), and octyl (C 8 )) was varied to prepare a series of room-temperature ionic liquids (RTILs), and experimental measurements of density and speed of sound at different temperatures ranging from (288.15 to 308.15) K for their aqueous and methanolic solutions in the dilute concentration region (0.01 to 0.30) mol . kg -1 were taken. The values of the compressibilities, expansivity and apparent molar properties for [C n mim][Br] in aqueous and methanolic solutions were determined at the investigated temperatures. The obtained apparent molar volumes and apparent molar isentropic compressibilities were fitted to the Redlich-Mayer and the Pitzer's equations from which the corresponding infinite dilution molar properties were obtained. The values of the infinite dilution molar properties were used to obtain some information about solute-solvent and solute-solute interactions. The thermodynamic properties of investigated ionic liquids in aqueous solutions have been compared with those in methanolic solutions. Also, the comparison between thermodynamic properties of investigated solutions and those of electrolyte solutions, polymer solutions, cationic surfactant solutions and tetraalkylammonium salt solutions have been made

  18. Effect of alkyl chain length and temperature on the thermodynamic properties of ionic liquids 1-alkyl-3-methylimidazolium bromide in aqueous and non-aqueous solutions at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Sadeghi, Rahmat [Department of Chemistry, University of Kurdistan, Sanandaj (Iran, Islamic Republic of)], E-mail: rahsadeghi@yahoo.com; Shekaari, Hemayat [Department of Chemistry, Faculty of Science, University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of); Hosseini, Rahim [Department of Chemistry, University of Kurdistan, Sanandaj (Iran, Islamic Republic of)

    2009-02-15

    The alkyl chain length of 1-alkyl-3-methylimidazolium bromide ([Rmim][Br], R = propyl (C{sub 3}), hexyl (C{sub 6}), heptyl (C{sub 7}), and octyl (C{sub 8})) was varied to prepare a series of room-temperature ionic liquids (RTILs), and experimental measurements of density and speed of sound at different temperatures ranging from (288.15 to 308.15) K for their aqueous and methanolic solutions in the dilute concentration region (0.01 to 0.30) mol . kg{sup -1} were taken. The values of the compressibilities, expansivity and apparent molar properties for [C{sub n}mim][Br] in aqueous and methanolic solutions were determined at the investigated temperatures. The obtained apparent molar volumes and apparent molar isentropic compressibilities were fitted to the Redlich-Mayer and the Pitzer's equations from which the corresponding infinite dilution molar properties were obtained. The values of the infinite dilution molar properties were used to obtain some information about solute-solvent and solute-solute interactions. The thermodynamic properties of investigated ionic liquids in aqueous solutions have been compared with those in methanolic solutions. Also, the comparison between thermodynamic properties of investigated solutions and those of electrolyte solutions, polymer solutions, cationic surfactant solutions and tetraalkylammonium salt solutions have been made.

  19. Improved spacers for high temperature gas-cooled heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Nordstroem, L A [Swiss Federal Institute for Reactor Research, Wuerenlingen (Switzerland)

    1984-07-01

    Experimental and analytical investigations in the field of heat exchanger thermohydraulics have been performed at EIR for many years, Basic studies have been carried out on heat transfer and pressure loss for tube bundles of different geometries and tube surfaces. As a part of this overall R+D programme for heat exchangers, investigations have been carried out on spacer pressure loss in bundles with longitudinal flow. An analytical spacer pressure loss model was developed which could handle different types of subchannel within the bundle. The model has been evaluated against experiments, using about 25 spacers of widely differing geometries. In a gas-cooled reactor it is important to keep the pressure loss over the primary circuit heat exchangers to a minimum. In exchangers with grid spacers these contribute a significant proportion of the overall bundle losses. For example, in the HHT Recuperator, with a shell-side pressure loss of 3.5 % of the inlet pressure, the spacers cause about one half of this loss. Reducing the loss to, say, 2.5 % results in an overall increase in plant efficiency by more than 1 % - a significant improvement Preliminary analysis identified 5 geometries in particular which were chosen for experimental evaluation as part of a joint project with the SULZER Company, to develop a low pressure-loss spacer for HHT heat exchangers (longitudinal counter-flow He/He and He/H{sub 2}O designs). The aim of the tests was to verify the low pressure-loss characteristics of these spacer grid types, as well as the quality of the results calculated by the computer code analytical model. The experimental and analytical results are compared in this report.

  20. Numerical analysis of the spacer grids' compression strength

    Energy Technology Data Exchange (ETDEWEB)

    Schettino, C.F.M.; Gouvea, J.P.; Medeiros, N., E-mail: carlosschettino@inb.gov.br, E-mail: jpg@metal.eeimvr.uff.br [Universidade Federal Fluminense (UFF), Volta Redonda, RJ (Brazil). Programa de Engenharia Metalurgica

    2013-07-01

    Among the components of the fuel assembly, the spacer grids play an important structural role during the energy generation process, mainly for their requirement to have enough structural strength to withstand lateral impact loads, due to fuel assembly shipping/handling and due to forces outcome from postulated accidents (earthquake and LOCA). This requirement ensures a proper geometry for cooling and for guide thimble straightness in the fuel assembly. In this way, the understanding of the macroscopic mechanical behavior of this component becomes essential even to any subsequent geometrical modifications to optimize the flue assemblies' structural behavior. In the present work, three-dimensional finite element models destined to provide consistent predictions of 16X16-type spacer grids lateral strength were proposed. Firstly, buckling tests based on results available in the literature were performed to establish a methodology for spacer grid finite element-based modeling. The, by considering a spacer grid interesting geometry and some possible variations associated to its fabrication, tolerance, the proposed numerical models were submitted to compression conditions to calculate the buckling force. Also, these models were validated for comparison with experimental buckling load results. Comparison of buckling predictions combined to observations of actual and simulated deformed spacer grids geometries permitted to verify the consistency and applicability of the proposed models. Thus, these numerical results show a good agreement between the and the experimental results. (author)

  1. Impact of spacer thickness on biofouling in forward osmosis

    KAUST Repository

    Valladares Linares, Rodrigo

    2014-06-01

    Forward osmosis (FO) indirect desalination systems integrate wastewater recovery with seawater desalination. Niche applications for FO systems have been reported recently, due to the demonstrated advantages compared to conventional high-pressure membrane processes such as nanofiltration (NF) and reverse osmosis (RO). Among them, wastewater recovery has been identified to be particularly suitable for practical applications. However, biofouling in FO membranes has rarely been studied in applications involving wastewater effluents. Feed spacers separating the membrane sheets in cross-flow systems play an important role in biofilm formation. The objective of this study was to determine the influence of feed spacer thickness (28, 31 and 46mil) on biofouling development and membrane performance in a FO system, using identical cross-flow cells in parallel studies. Flux development, biomass accumulation, fouling localization and composition were determined and analyzed. For all spacer thicknesses, operated at the same feed flow and the same run time, the same amount of biomass was found, while the flux reduction decreased with thicker spacers. These observations are in good agreement with biofouling studies for RO systems, considering the key differences between FO and RO. Our findings contradict previous cross-flow studies on particulate/colloidal fouling, where higher cross-flow velocities improved system performance. Thicker spacers reduced the impact of biofouling on FO membrane flux. © 2014 Elsevier Ltd.

  2. Impact of spacer thickness on biofouling in forward osmosis.

    Science.gov (United States)

    Valladares Linares, R; Bucs, Sz S; Li, Z; AbuGhdeeb, M; Amy, G; Vrouwenvelder, J S

    2014-06-15

    Forward osmosis (FO) indirect desalination systems integrate wastewater recovery with seawater desalination. Niche applications for FO systems have been reported recently, due to the demonstrated advantages compared to conventional high-pressure membrane processes such as nanofiltration (NF) and reverse osmosis (RO). Among them, wastewater recovery has been identified to be particularly suitable for practical applications. However, biofouling in FO membranes has rarely been studied in applications involving wastewater effluents. Feed spacers separating the membrane sheets in cross-flow systems play an important role in biofilm formation. The objective of this study was to determine the influence of feed spacer thickness (28, 31 and 46 mil) on biofouling development and membrane performance in a FO system, using identical cross-flow cells in parallel studies. Flux development, biomass accumulation, fouling localization and composition were determined and analyzed. For all spacer thicknesses, operated at the same feed flow and the same run time, the same amount of biomass was found, while the flux reduction decreased with thicker spacers. These observations are in good agreement with biofouling studies for RO systems, considering the key differences between FO and RO. Our findings contradict previous cross-flow studies on particulate/colloidal fouling, where higher cross-flow velocities improved system performance. Thicker spacers reduced the impact of biofouling on FO membrane flux. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Analyses of the Collapse Behavior of a Spacer Grid

    International Nuclear Information System (INIS)

    Jang, Myung-Geun; Na, Geum Ju; Jag, Yeon-Hui; Kim, Hee Cheol; Kim, Jong-Bong; Kim, Jaeyoug

    2016-01-01

    In order to investigate the protection capability of a spacer grid assembly for impact load, a hammer impact test has been carried out. The crush strength is measured in the hammer impact test. Song et al. carried out the experiment and finite element analysis for the hammer impact test for various weld line depth. Park et al. designed the spacer grid shape to get required crush strength via finite element analysis. Song et al. also optimized the spacer grid shape to maximize the crush strength, and carried out the finite element analysis for the hammer impact test considering the weld properties. Kim et al. carried out finite element analysis for various guide tube hole shape and compared the crush shape and crush strength. In this study, the effect of shape defect on the crush behavior in the hammer impact test is investigated. The spacer grid cannot be exactly the square. Therefore a lateral displacement (imperfection) is imposed to square spacer grid and then hammer impact is carried out. The effect of the lateral imperfection on the crush strength is investigated. The effect of the shape defect on the crushing behavior in the hammer impact test is investigated by finite element analysis. It is shown that the collapse become severe as the lateral imperfection displacement increases, especially when the imperfection is greater than or equal to 0.7 mm

  4. Zircaloy spacer grid for boiling light water reactors

    International Nuclear Information System (INIS)

    Borgiani, F.; Cali', G.P.; Cerretti, P.; Pazzo, P.

    1975-01-01

    The need to increase the neutronic efficiency of the new cores of BWR's, lead to study types of spacer-grids made of low neutronic absorption materials as zircaloy-4. The particular mechanical behaviour of this material suggested to design a spacer-grids such as to utilize only blanking, slotting and bending operations as plastic forming and to avoid therefore drawing effects. The optimization of the bending procedures lead to a final spacer-grids configuration equally stiff in all directions and planes. Only for the ''elastic constraints'' nichel alloy sheets were used to made easy the whole spacer design. The ''rigid constraints'', supporting the rods, have been obtained directly from the spacer structure. Calculations were performed to verify the mechanical strength of the main grid components. In this framework a computer code was developed to find the best elastic characteristic of the ''elastic constraints'' taking into account the machining tolerances. Some original methods to test the integral behaviour of the grid assembled as well as the procedures to be adopted for its best maintenance, are described

  5. Numerical analysis of the spacer grids' compression strength

    International Nuclear Information System (INIS)

    Schettino, C.F.M.; Gouvea, J.P.; Medeiros, N.

    2013-01-01

    Among the components of the fuel assembly, the spacer grids play an important structural role during the energy generation process, mainly for their requirement to have enough structural strength to withstand lateral impact loads, due to fuel assembly shipping/handling and due to forces outcome from postulated accidents (earthquake and LOCA). This requirement ensures a proper geometry for cooling and for guide thimble straightness in the fuel assembly. In this way, the understanding of the macroscopic mechanical behavior of this component becomes essential even to any subsequent geometrical modifications to optimize the flue assemblies' structural behavior. In the present work, three-dimensional finite element models destined to provide consistent predictions of 16X16-type spacer grids lateral strength were proposed. Firstly, buckling tests based on results available in the literature were performed to establish a methodology for spacer grid finite element-based modeling. The, by considering a spacer grid interesting geometry and some possible variations associated to its fabrication, tolerance, the proposed numerical models were submitted to compression conditions to calculate the buckling force. Also, these models were validated for comparison with experimental buckling load results. Comparison of buckling predictions combined to observations of actual and simulated deformed spacer grids geometries permitted to verify the consistency and applicability of the proposed models. Thus, these numerical results show a good agreement between the and the experimental results. (author)

  6. A non-electrostatic spacer for aerosol delivery

    DEFF Research Database (Denmark)

    Bisgaard, H; Anhøj, J; Klug, B

    1995-01-01

    A pear shaped non-electrostatic spacer, composed of steel with a volume of 250 ml and equipped with a facemask containing integrated inlet and outlet valves for inspiration and expiration, was compared with three plastic spacers. The plastic spacers were primed with repeated puffs from a budesonide...... pressurised metered dose inhaler (p-MDI) to minimise the electrostatic charge on the plastic. The procedure prolonged the half life (t1/2) of the aerosol in the Nebuhaler from nine to 32 seconds. A normal cleaning procedure reduced the aerosol t1/2 back to baseline. The t1/2 of the aerosol in the metal spacer...... was 27 seconds and independent of the use of p-MDI. In vitro the maximum dose of budesonide from a p-MDI, expressed as a percentage of the nominal dose, was 56% from the non-electrostatic spacer, 61% from the Nebuhaler, 45% from the Babyhaler, and 30% from the AeroChamber. In 124 children, age 6 months...

  7. Impact of spacer thickness on biofouling in forward osmosis

    KAUST Repository

    Valladares Linares, Rodrigo; Bucs, Szilard; Li, Z.; AbuGhdeeb, M.; Amy, Gary L.; Vrouwenvelder, Johannes S.

    2014-01-01

    Forward osmosis (FO) indirect desalination systems integrate wastewater recovery with seawater desalination. Niche applications for FO systems have been reported recently, due to the demonstrated advantages compared to conventional high-pressure membrane processes such as nanofiltration (NF) and reverse osmosis (RO). Among them, wastewater recovery has been identified to be particularly suitable for practical applications. However, biofouling in FO membranes has rarely been studied in applications involving wastewater effluents. Feed spacers separating the membrane sheets in cross-flow systems play an important role in biofilm formation. The objective of this study was to determine the influence of feed spacer thickness (28, 31 and 46mil) on biofouling development and membrane performance in a FO system, using identical cross-flow cells in parallel studies. Flux development, biomass accumulation, fouling localization and composition were determined and analyzed. For all spacer thicknesses, operated at the same feed flow and the same run time, the same amount of biomass was found, while the flux reduction decreased with thicker spacers. These observations are in good agreement with biofouling studies for RO systems, considering the key differences between FO and RO. Our findings contradict previous cross-flow studies on particulate/colloidal fouling, where higher cross-flow velocities improved system performance. Thicker spacers reduced the impact of biofouling on FO membrane flux. © 2014 Elsevier Ltd.

  8. Differentiation between Aspergillus flavus and Aspergillus parasiticus from Pure Culture and Aflatoxin-Contaminated Grapes Using PCR-RFLP Analysis of aflR-aflJ Intergenic Spacer

    International Nuclear Information System (INIS)

    El Khoury, A.; Atoui, A.; Lebrihi, A.; Rizk, T.; Lteif, R.; Kallassy, M.

    2011-01-01

    Aflatoxins (AFs) represent the most important single mycotoxin-related food safety problem in developed and developing countries as they have adverse effects on human and animal health. They are produced mainly by Aspergillus flavus and A. parasiticus. Both species have different aflatoxinogenic profile. In order to distinguish between A. flavus and A. parasiticus, gene-specific primers were designed to target the intergenic spacer (IGS) for the AF biosynthesis genes, aflJ and aflR. Polymerase chain reaction (PCR) products were subjected to restriction endonuclease analysis using BglII to look for restriction fragment length polymorphisms (RFLPs). Our result showed that both species displayed different PCR-based RFLP (PCR-RFLP) profile. PCR products from A. flavus cleaved into 3 fragments of 362, 210, and 102 bp. However, there is only one restriction site for this enzyme in the sequence of A. parasiticus that produced only 2 fragments of 363 and 311 bp. The method was successfully applied to contaminated grapes samples. This approach of differentiating these 2 species would be simpler, less costly, and quicker than conventional sequencing of PCR products and/or morphological identification. (author)

  9. Experimental and numerical characterization of the water flow in spacer-filled channels of spiral-wound membranes

    KAUST Repository

    Bucs, Szilard

    2015-09-25

    Micro-scale flow distribution in spacer-filled flow channels of spiral-wound membrane modules was determined with a particle image velocimetry system (PIV), aiming to elucidate the flow behaviour in spacer-filled flow channels. Two-dimensional water velocity fields were measured in a flow cell (representing the feed spacer-filled flow channel of a spiral wound reverse osmosis membrane module without permeate production) at several planes throughout the channel height. At linear flow velocities (volumetric flow rate per cross-section of the flow channel considering the channel porosity, also described as crossflow velocities) used in practice (0.074 and 0.163 m∙s-1) the recorded flow was laminar with only slight unsteadiness in the upper velocity limit. At higher linear flow velocity (0.3 m∙s-1) the flow was observed to be unsteady and with recirculation zones. Measurements made at different locations in the flow cell exhibited very similar flow patterns within all feed spacer mesh elements, thus revealing the same hydrodynamic conditions along the length of the flow channel. Three-dimensional (3-D) computational fluid dynamics simulations were performed using the same geometries and flow parameters as the experiments, based on steady laminar flow assumption. The numerical results were in good agreement (0.85-0.95 Bray-Curtis similarity) with the measured flow fields at linear velocities of 0.074 and 0.163 m∙s-1, thus supporting the use of model-based studies in the optimization of feed spacer geometries and operational conditions of spiral wound membrane systems.

  10. Experimental and numerical characterization of the water flow in spacer-filled channels of spiral-wound membranes.

    Science.gov (United States)

    Bucs, Szilard S; Linares, Rodrigo Valladares; Marston, Jeremy O; Radu, Andrea I; Vrouwenvelder, Johannes S; Picioreanu, Cristian

    2015-12-15

    Micro-scale flow distribution in spacer-filled flow channels of spiral-wound membrane modules was determined with a particle image velocimetry system (PIV), aiming to elucidate the flow behaviour in spacer-filled flow channels. Two-dimensional water velocity fields were measured in a flow cell (representing the feed spacer-filled flow channel of a spiral wound reverse osmosis membrane module without permeate production) at several planes throughout the channel height. At linear flow velocities (volumetric flow rate per cross-section of the flow channel considering the channel porosity, also described as crossflow velocities) used in practice (0.074 and 0.163 m·s(-1)) the recorded flow was laminar with only slight unsteadiness in the upper velocity limit. At higher linear flow velocity (0.3 m·s(-1)) the flow was observed to be unsteady and with recirculation zones. Measurements made at different locations in the flow cell exhibited very similar flow patterns within all feed spacer mesh elements, thus revealing the same hydrodynamic conditions along the length of the flow channel. Three-dimensional (3-D) computational fluid dynamics simulations were performed using the same geometries and flow parameters as the experiments, based on steady laminar flow assumption. The numerical results were in good agreement (0.85-0.95 Bray-Curtis similarity) with the measured flow fields at linear velocities of 0.074 and 0.163 m·s(-1), thus supporting the use of model-based studies in the optimization of feed spacer geometries and operational conditions of spiral wound membrane systems. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Kondo length in bosonic lattices

    Science.gov (United States)

    Giuliano, Domenico; Sodano, Pasquale; Trombettoni, Andrea

    2017-09-01

    Motivated by the fact that the low-energy properties of the Kondo model can be effectively simulated in spin chains, we study the realization of the effect with bond impurities in ultracold bosonic lattices at half filling. After presenting a discussion of the effective theory and of the mapping of the bosonic chain onto a lattice spin Hamiltonian, we provide estimates for the Kondo length as a function of the parameters of the bosonic model. We point out that the Kondo length can be extracted from the integrated real-space correlation functions, which are experimentally accessible quantities in experiments with cold atoms.

  12. Experimental study of mechanical properties on spacer in NHR

    International Nuclear Information System (INIS)

    Jiang Yueyuan; Shi Jibing; Xu Yong

    2007-01-01

    The spacer of NHR-200 is composed mainly of the inner, outer and cornual strips which are ranged in egg-crate of 12 x 12-3. First, the pre-distortion of three kinds of three-arc springs on reactor working condition and their related clipping-force ranges are analyzed in this paper. Secondly, the mechanical experiments of 1:1 prototype, such as the load-distortion experiments, which the load and distortion are respectively measured by strain gauge and displacement sensor, of three kinds of springs, rigid supports and the spacers in two different directions are carried out on a special experimental facility. The experimental results show that the spacer can completely meet the design demands of mechanical properties of the fuel assemblies in NHR-200. (authors)

  13. Effect of a spacer moiety on radiometal labelled Neurotensin derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Mascarin, A.; Valverde, I.E.; Mindt, T.L. [Univ. of Basel Hospital (Switzerland). Div. of Radiopharmaceutical Chemistry

    2013-07-01

    The binding sequence of the regulatory peptide Neurotensin, NT(8-13), represents a promising tumour-specific vector for the development of radiopeptides useful in nuclear oncology for the diagnosis (imaging) and therapy of cancer. A number of radiometal-labelled NT(8-13) derivatives have been reported, however, the effect of the spacer which connects the vector with the radiometal complex has yet not been investigated systematically. Because a spacer moiety can influence potentially important biological characteristics of radiopeptides, we synthesized three [DOTA({sup 177}Lu)]-X-NT(8-13) derivatives and evaluated the effect of a spacer (X) on the physico-chemical properties of the conjugate including lipophilicity, stability, and in vitro receptor affinity and cell internalization. (orig.)

  14. Lower end fitting debris collector and end cap spacer grid

    International Nuclear Information System (INIS)

    Bryan, W.J.

    1990-01-01

    This patent describes a nuclear reactor having fuel assemblies including an upper end fitting and spaced nuclear fuel rod spacer grids for supporting and spacing a plurality of elongated nuclear fuel rods. Each includes a hollow active portion of nuclear fuel filled cladding intermediate the rod ends and tapering end cap of solid material with a circumferential groove on the rod end which first encounters reactor coolant flow, a lower end filtering debris collector and end cap spacer grid for capturing and retaining deleterious debris carried by reactor coolant before it enters the active region of a fuel assembly and creates fuel rod cladding damage

  15. Spacer grid for a nuclear reactor fuel assembly

    International Nuclear Information System (INIS)

    Jabsen, F.S.

    1978-01-01

    The spacer grid consists of pairs of plates forming rectangular cells and enclosing the cylindrical fuel assemblies. They have got rigid as well as elastic projections extending into the cells and holding the fuel assemblies. Additional pairs of plates are arranged in about the center of the grid of plates. They have got only elastic projections extending on both sides of the plates into one cell each. This spacer grid may be used for reactor cores with and without fuel channels. By the combination of spring-elastic and rigid projections there is obtained a reinforced outer tie. Hydraulic pressure losses, parasitic neutron capture, and hot spots are essentially reduced. (DG) [de

  16. Biomechanical Analysis of an Expandable Lumbar Interbody Spacer.

    Science.gov (United States)

    Soriano-Baron, Hector; Newcomb, Anna G U S; Malhotra, Devika; Palma, Atilio E; Martinez-Del-Campo, Eduardo; Crawford, Neil R; Theodore, Nicholas; Kelly, Brian P; Kaibara, Taro

    2018-06-01

    Recently developed expandable interbody spacers are widely accepted in spinal surgery; however, the resulting biomechanical effects of their use have not yet been fully studied. We analyzed the biomechanical effects of an expandable polyetheretherketone interbody spacer inserted through a bilateral posterior approach with and without different modalities of posterior augmentation. Biomechanical nondestructive flexibility testing was performed in 7 human cadaveric lumbar (L2-L5) specimens followed by axial compressive loading. Each specimen was tested under 6 conditions: 1) intact, 2) bilateral L3-L4 cortical screw/rod (CSR) alone, 3) WaveD alone, 4) WaveD + CSR, 5) WaveD + bilateral L3-L4 pedicle screw/rod (PSR), and 6) WaveD + CSR/PSR, where CSR/PSR was a hybrid construct comprising bilateral cortical-level L3 and pedicle-level L4 screws interconnected by rods. The range of motion (ROM) with the interbody spacer alone decreased significantly compared with the intact condition during flexion-extension (P = 0.02) but not during lateral bending or axial rotation (P ≥ 0.19). The addition of CSR or PSR to the interbody spacer alone condition significantly decreased the ROM compared with the interbody spacer alone (P ≤ 0.002); and WaveD + CSR, WaveD + PSR, and WaveD + CSR/PSR (hybrid) (P ≥ 0.29) did not differ. The axial compressive stiffness (resistance to change in foraminal height during compressive loading) with the interbody spacer alone did not differ from the intact condition (P = 0.96), whereas WaveD + posterior instrumentation significantly increased compressive stiffness compared with the intact condition and the interbody spacer alone (P ≤ 0.001). The WaveD alone significantly reduced ROM during flexion-extension while maintaining the axial compressive stiffness. CSR, PSR, and CSR/PSR hybrid constructs were all effective in augmenting the expandable interbody spacer system and improving its stability. Copyright © 2018 Elsevier Inc. All

  17. PairWise Neighbours database: overlaps and spacers among prokaryote genomes

    Directory of Open Access Journals (Sweden)

    Garcia-Vallvé Santiago

    2009-06-01

    Full Text Available Abstract Background Although prokaryotes live in a variety of habitats and possess different metabolic and genomic complexity, they have several genomic architectural features in common. The overlapping genes are a common feature of the prokaryote genomes. The overlapping lengths tend to be short because as the overlaps become longer they have more risk of deleterious mutations. The spacers between genes tend to be short too because of the tendency to reduce the non coding DNA among prokaryotes. However they must be long enough to maintain essential regulatory signals such as the Shine-Dalgarno (SD sequence, which is responsible of an efficient translation. Description PairWise Neighbours is an interactive and intuitive database used for retrieving information about the spacers and overlapping genes among bacterial and archaeal genomes. It contains 1,956,294 gene pairs from 678 fully sequenced prokaryote genomes and is freely available at the URL http://genomes.urv.cat/pwneigh. This database provides information about the overlaps and their conservation across species. Furthermore, it allows the wide analysis of the intergenic regions providing useful information such as the location and strength of the SD sequence. Conclusion There are experiments and bioinformatic analysis that rely on correct annotations of the initiation site. Therefore, a database that studies the overlaps and spacers among prokaryotes appears to be desirable. PairWise Neighbours database permits the reliability analysis of the overlapping structures and the study of the SD presence and location among the adjacent genes, which may help to check the annotation of the initiation sites.

  18. Mating of a PROSTALAC spacer with an intramedullary nail for reconstruction of an infected interprosthetic femoral shaft fracture: a case report.

    Science.gov (United States)

    Kamath, Atul F; Austin, Daniel; Lee, Gwo-Chin

    2012-08-01

    Reconstruction for concurrent infection of an ipsilateral total hip arthroplasty (THA) and total knee arthroplasty (TKA) is a challenge. We report a 2-stage reconstruction of a THA for chronic infection of both the THA and TKA with severe femoral bone loss secondary to interprosthetic fractures. The reconstruction involved using a custom-made, temporary, antibiotic-impregnated PROSTALAC spacer mated with an intramedullary nail. The acetabulum was then exposed and the necrotic cartilage was removed and curetted. The acetabulum was reamed to accept a PROSTALAC acetabular shell. The shell was cemented into the acetabulum with antibiotic cement. The custom-made spacer was then inserted distally first into the tibia. The distal end of the intramedullary nail was interlocked with a bicortical bolt to minimise nail rotation. Antibiotic-impregnated cement was moulded around the nail and spacer. The proximal end of the spacer was then reduced into the acetabular socket, and the joint was irrigated and the wound closed. A customised abduction brace was fitted, and partial weight bearing was allowed. Sufficient leg length, soft-tissue tension, and range of hip motion were restored, and a total femur and constrained liner was re-implanted 4 months later. Mating of an intramedullary nail with a PROSTALAC spacer is a viable reconstructive option.

  19. Comparative studies of 111In-labeled monoclonal antibody using spacer-containing and non-spacer bifunctional chelates. 2

    International Nuclear Information System (INIS)

    Sun, Baofu

    1994-01-01

    Indium-111-labeled A7 monoclonal antibodies using two spacer-containing chelates, succinimido-EGS-DTPA (EGS-DTPA: diester spacer) and maleimido-C10-Bz-EDTA (C10-Bz-EDTA: hydrocarbon spacer) were investigated in human LS180 colon tumor bearing nude mice and were compared with two non-spacer chelates, cyclic DTPA dianhydride (cDTPAA) and isothiocyanatobenzyl-EDTA (SCN-Bz-EDTA). Compared with immunoconjugates using non-spacer chelates, immunoconjugates using spacer-containing chelates, especially C10-Bz-EDTA-A7 showed lower 111 In activity in normal organs. The radioactivity in the liver for C10-Bz-EDTA-A7 decreased continuously till 96 hrs postinjection, however, this liver radioactivity for EGS-DTPA-A7 showed little change after 24 hrs. Moreover, in liver subcellular distribution study, EGS-DTPA-A7 showed a higher activity retention in mitochondrial fraction which contained lysosome, a place for metabolizing and storing of 111 In labeled antibody, than that of C10-Bz-EDTA-A7. The C10-Bz-EDTA-A7 conjugate demonstrated more preferable tumor-to-non tumor contrast on the scintigrams than that found with other three immunoconjugates. Up to 96 hrs postinjection, tumor bearing nude mice injecting with immunoconjugates using spacer-containing chelates exreted twice radioactivity from whole body than that excreted by using non-spacer chelates. Interestingly, different from other three chelates, C10-Bz-EDTA-A7 were mainly excreted via feces. We conclude that the decrease of radioactivity in normal tissues in the case of EGS-DTPA-A7 was due to the rapid decrease of activity in the blood, while in the case of C10-Bz-EDTA-A7 it was due to the quickly excreted small metabolite through faces. 111 In labeled C10-Bz-EDTA conjugate is superior, at least when conjugated with A7, to other three chelate conjugates used in this study. (author)

  20. Shelf life of pie caps with biodegradable films as spacers

    Directory of Open Access Journals (Sweden)

    Daniela Verónica Escobar Gianni

    2013-01-01

    Full Text Available Commonly pie caps at market use polyethylene films as spacers between them. This paper studies the conventional spacers replacement with edible and biodegradable films made with whey protein isolate (WPI and potassium sorbate as a preservative. Besides facilitating the separation of pie caps, with this application is intended to increase their shelf life. The films made by the compression molding method were used as spacers in pie caps without preservative in their formula (A and with preservative (B and they were compared with conventional polyethylene spacers (C. During four months, monthly sensory, microbiological and physicochemical (humidity evaluations were done on the pie caps, together with humidity and solubility evaluations of the films. None of the samples showed microbiological or sensory deterioration. The sensory attributes showed no or slight difference in study time. Between samples the differences were minor: the best scores were for sample A in color, sample C in flavor, and samples B and C in texture and overall liking. The edible films have an interesting potential for this application, although studies in disguise the flavor of serum should be done.

  1. Deformation behavior of cell spring of an irradiated spacer grid

    International Nuclear Information System (INIS)

    Jin, Y. G.; Baek, S. J.; Ryu, W. S.; Kim, G. S.; Yoo, B. O.; Kim, D. S.; Ahn, S. B.; Chun, Y. B.; Choo, Y. S.

    2012-01-01

    Mechanical properties of a space grid of a fuel assembly are of great importance for fuel operation reliability in extended fuel burnup and duration of fuel life. The spacer grid with inner and outer straps has cell spring and dimples, which are in contact with the fuel rod. The spacer grids supporting the fuel rods absorb vibration impacts due to the reactor coolant flow and also grid spring force is decreasing under irradiation. This reduction of contact force might cause the grid to rod fretting wear. The fretting failure of the fuel rod is one of the significant issues recently in the nuclear industry from an economical as well as a safety concern. Thus, it is important to understand the characteristics of cell spring behavior for an irradiated spacer grid. In the present study, the stiffness test and dimensional measurement of cell springs were conducted to investigate the deformation behavior of cell springs of an irradiated spacer grid in a hot cell at IMEF (irradiated materials examination facility) of KAERI

  2. Knowledge of spacer device, peak flow meter and inhaler technique ...

    African Journals Online (AJOL)

    Background: Metered dose inhalers are cornerstone in effective management of bronchial asthma when correctly used. Most studies hitherto have focused on assessing patient's knowledge of inhaler technique. We sought to assess the knowledge of inhaler technique, spacer device and peak flow meter among doctors and ...

  3. On the impact analysis of a PWR spacer grid

    International Nuclear Information System (INIS)

    Song, Kee Nam; Lee, S. H.

    2012-01-01

    A spacer grid, which is an interconnected array of slotted grid straps and is welded at the intersections to form an egg crate structure, is one of the most important structural components in a PWR fuel assembly. From a structural point of view, the spacer grid is required to have sufficient crush strength under lateral loads so that nuclear fuel rods are maintained in a cool able geometry, and that control rods can be inserted. The capacity of a spacer grid to resist lateral loads is usually characterized in terms of its crush strength, and it was reported that the lateral crush strength of the spacer grid is closely related with welding quality of the spacer grid. Microstructures in the weld zone, including a heat affected zone (HAZ), are different from that in a parent material. Consequently, the mechanical properties in the weld zone are different from those in the parent material to some extent. When a welded structure is loaded, the mechanical behavior of the welded structure might be different from the case of a structure with homogeneous mechanical properties. Nonetheless, mechanical properties in the welded structure have been neglected in many structural analyses of the spacer grid due to a lack of mechanical properties in the weld zone. When the weld zone is very narrow and the interfaces are not clear, it is difficult to take tensile test specimens in the weld zone. The reason for this is that the mechanical properties in the parent material are usually used in the structural analyses in the welded structure. As an aside, it has been recently determined that the ball indentation technique has the potential to be an excellent substitute for a standard tensile test, particularly in the case of small specimens or property gradient materials such as welds. In this study, to investigate the effect on the mechanical behavior of the spacer grid when using weld mechanical properties, strength analyses considering the weld mechanical properties recently obtained

  4. 3-D flow analyses for design of nuclear fuel spacer

    Energy Technology Data Exchange (ETDEWEB)

    Karouta, Z. [ABB Combustion Engineering, Windsor, CT (United States); GU, Chun-Yuan [ABB Corporate Research, Vaesteras (Sweden); Schoelin, B. [ABB Atom AB, Vaesteras (Sweden)

    1995-09-01

    The Computational Fluid Dynamics (CFD) code, CFDS-FLOW3D, was used to develop improved fuel designs for PWR cores. It was used primarily to understand the fluid dynamics of grid spacers, the mass transfer between subchannels caused by spacers and in the long term to develop two-phase models which enable prediction of critical heat flux in PWR fuel. A single subchannel of one grid span was modeled. In this model different spacer designs with mixing devices were analyzed. A special treatment of the boundary condition was developed making use of flow symmetry to model the mass transfer between different subchannels and minimize the size of the computational model. This reduced the computational model to a fraction of a subchannel using traditional periodic boundary conditions. The Navier-Stokes equation was solved for the liquid and the flow turbulence was modeled by k-{xi} turbulence model. The spacer and mixing device were treated as infinite thin surfaces in the model and a zero velocity condition and turbulent wall function were applied on each side of the thin surfaces. This approach simulated the swirl from the mixing devices well, but had the drawback of not predicting pressure drop accurately since the wake behind the plates and the acceleration effect of the spacers were ignored. CFDS-FLOW3D models with mixing devices were applied in the single-phase flow regime. Velocity profiles from the CFDS-FLOW3D models were compared to Laser Doppler Velocimeter measurements taken from the flow field downstream of spaces in a full scale, cold water test loop. The predicted axial and lateral velocity profiles were in good agreement with the measurements. The evaluation of the performance of different spacer devices was made by comparing the swirl ratio downstream of the grid spacers. It is planned to evaluate heat transfer coefficient downstream of the spaces, to implement two-phase flow models, and to model the superheated boundary layer on the surface of the fuel rod.

  5. Optimisation of automated ribosomal intergenic spacer analysis for the estimation of microbial diversity in fynbos soil

    Directory of Open Access Journals (Sweden)

    Karin Jacobs

    2010-07-01

    Full Text Available Automated ribosomal intergenic spacer analysis (ARISA has become a commonly used molecular technique for the study of microbial populations in environmental samples. The reproducibility and accuracy of ARISA, with and without the polymerase chain reaction (PCR are important aspects that influence the results and effectiveness of these techniques. We used the primer set ITS4/ITS5 for ARISA to assess the fungal community composition of two sites situated in the Sand Fynbos. The primer set proved to deliver reproducible ARISA profiles of the fungal community composition with little variation observed between ARISA-PCRs. Variation that occurred in a sample due to repeated DNA extraction is expected for ecological studies. This reproducibility made ARISA a useful tool for the assessment and comparison of diversity in ecological samples. In this paper, we also offered particular suggestions concerning the binning strategy for the analysis of ARISA profiles.

  6. Effect of spacer grids on CHF in tube bundles

    International Nuclear Information System (INIS)

    Jayanti, Sreenivas; Valette, Michel

    2004-01-01

    Spacers grids are used to support tube bundles in steam generators and in nuclear reactor fuel assemblies. These grids interface with the flow and heat transfer in a number of ways and their effect has been studied by a number of researchers. It is known that generally they have a beneficial effect on critical heat flux (CHF) in typical nuclear reactor assemblies. However, the enhancement obtained depends on the geometric characteristics of the spacer grids as well as on the parameter range in terms of pressure, local mass velocity and quality. In the present study, the problem is approached in the context of a one-dimensional three-field model. Unlike in previous approaches, no specific modeling of the constitutive laws is made to account for spacer effects and only the geometric details such as the reduction in the cross-sectional area and the hydraulic diameter are included in the calculation which is otherwise the same as that for flow through a single tube. It is shown by comparison with literature data that this approach leads to satisfactory prediction of the thermal-hydraulic effects of spacers and that the beneficial effects of spacers on dry out can be manifested only when the entrainment rate is neither too high nor too low. Their effect on reducing the post-dry out wall temperature is also limited to certain cases. The present work has been performed as part of the EDF-CEA Neptune project also supported by the Institut de Radioprotection et de Surete Nucleaire (IRSN, France) and FRAMATOME-ANP. NEPTUNE is a new set of two phase thermalhydraulic computer codes devoted to safety analysis of nuclear power plants. (author)

  7. Biofouling Control in Spiral-Wound Membrane Systems: Impact of Feed Spacer Modification and Biocides

    KAUST Repository

    Siddiqui, Amber

    2016-01-01

    was developed. The combination of modeling and experimental testing of 3D printed spacers is a promising strategy to develop advanced spacers aiming to reduce the impact of biofilm formation on membrane performance and to improve the cleanability of spiral

  8. Impact of feed spacer and membrane modification by hydrophilic, bactericidal and biocidal coating on biofouling control

    KAUST Repository

    Araú jo, Paula A.; Miller, Daniel J.; Correia, Patrí cia B.; van Loosdrecht, Mark C.M.; Kruithof, Joop C.; Freeman, Benny Dean; Paul, Donald; Vrouwenvelder, Johannes S.

    2012-01-01

    surface modification agents expected to resist protein and bacterial adhesion, while copper feed spacer coatings and biocides infused in feed spacers are expected to restrict biological growth. Our studies showed that polydopamine and polydopamine-. g

  9. Development and characterization of 3D-printed feed spacers for spiral wound membrane systems

    KAUST Repository

    Siddiqui, Amber; Farhat, Nadia; Bucs, Szilard; Valladares Linares, Rodrigo; Picioreanu, Cristian; Kruithof, Joop C.; van Loosdrecht, Mark C.M.; Kidwell, James; Vrouwenvelder, Johannes S.

    2016-01-01

    suggested that the impact of spacers on hydraulics and biofouling can be improved. A good agreement was found for the modeled and measured relationship between linear flow velocity and pressure drop for feed spacers with the same geometry, indicating

  10. A new series of two-ring-based side chain liquid crystalline polymers: synthesis and mesophase characterization

    CSIR Research Space (South Africa)

    Reddy, GSM

    2013-05-01

    Full Text Available A new series of side chain liquid crystalline polymers containing a core, a butamethylenoxy spacer, ester groups, and terminal alkoxy groups were synthesised and their structures were confirmed. The core was constructed with two phenyl rings...

  11. Biofouling Control in Spiral-Wound Membrane Systems: Impact of Feed Spacer Modification and Biocides

    KAUST Repository

    Siddiqui, Amber

    2016-12-01

    High-quality drinking water can be produced with membrane-based filtration processes like reverse osmosis and nanofiltration. One of the major problems in these membrane systems is biofouling that reduces the membrane performance, increasing operational costs. Current biofouling control strategies such as pre-treatment, membrane modification, and chemical cleaning are not sufficient in all cases. Feed spacers are thin (0.8 mm), complex geometry meshes that separate membranes in a module. The main objective of this research was to evaluate whether feed spacer modification is a suitable strategy to control biofouling. Membrane fouling simulator studies with six feed spacers showed differences in biofouled spacer performance, concluding that (i) spacer geometry influences biofouling impact and (ii) biofouling studies are essential for evaluation of spacer biofouling impact. Computed tomography (CT) was found as a suitable technique to obtain three-dimensional (3D) measurements of spacers, enabling more representative mathematical modeling of hydraulic behavior of spacers in membrane systems. A strategy for developing, characterizing, and testing of spacers by numerical modeling, 3D printing of spacers and experimental membrane fouling simulator studies was developed. The combination of modeling and experimental testing of 3D printed spacers is a promising strategy to develop advanced spacers aiming to reduce the impact of biofilm formation on membrane performance and to improve the cleanability of spiral-wound membrane systems.

  12. Differences in the second internal transcribed spacer of four species of Nematodirus (Nematoda: Molineidae).

    Science.gov (United States)

    Newton, L A; Chilton, N B; Beveridge, I; Gasser, R B

    1998-02-01

    Genetic differences among Nematodirus spathiger, Nematodirus filicollis, Nematodirus helvetianus and Nematodirus battus in the nucleotide sequence of the second internal transcribed spacer (ITS-2) of ribosomal DNA ranged from 3.9 to 24.7%. Pairwise comparisons of their ITS-2 sequences indicated that the most genetically similar species were N. spathiger and N. helvetianus. N. battus was the most genetically distinct species, with differences ranging from 22.8 to 24.7% with respect to the other three species. Some of the nucleotide differences among species provided different endonuclease restriction sites that could be used in restriction fragment length polymorphism studies. The ITS-2 sequence data may prove useful in studies of the systematics of molineid nematodes.

  13. An insulating grid spacer for large-area MICROMEGAS chambers

    International Nuclear Information System (INIS)

    Bernard, D.; Delagrange, H.; D'Enterria, D.G.; Guay, M.L.M. Le; Martinez, G.; Mora, M.J.; Pichot, P.; Roy, D.; Schutz, Y.; Gandi, A.; Oliveira, R. de

    2002-01-01

    We present a novel design for large-area gaseous detectors based on the MICROMEGAS technology. This technology incorporates an insulating grid, sandwiched between the micro-mesh and the anode-pad plane, which provides a uniform 200 μm amplification gap. The uniformity of the amplification gap thickness has been verified. The gain performances of the detector are presented and compared to the values obtained with detectors using cylindrical micro spacers. The new design presents several technical and financial advantages

  14. Successful implementation of spacer treatment guideline for acute asthma

    OpenAIRE

    Powell, C; Maskell, G; Marks, M; South, M; Robertson, C; LENNEY, W.

    2001-01-01

    AIMS—To develop and implement an evidence based guideline for the treatment of acute asthma using a metered dose inhaler and spacer combination.
METHODS—Defined strategies were used for the development and implementation of a guideline, assessed by a prospective, descriptive, study using notes review, and patient, nursing, and medical staff telephone contact. The setting was a tertiary referral hospital in Victoria, Australia with 25 000 yearly admissions, and asthma acco...

  15. Device for a nuclear reactor. [Fuel element spacers

    Energy Technology Data Exchange (ETDEWEB)

    Foulds, R B; Kasberg, A H; Puechl, K H; Bleiberg, M L

    1972-03-08

    A spacer design for fuel element clusters for PWR type reactors is described. It consists of a frame supporting an egg-carton like grid each sector of which is provided with springs which grip the fuel pins. The spring design is such as to prevent fuel pin vibrations and at same time accommodate fuel pin deformations. Formulae for the calculation of natural frequencies, spring stiffness and friction loads are presented.

  16. Bimetallic spacer means for a nuclear fuel assembly

    International Nuclear Information System (INIS)

    Anthony, A.J.

    1981-01-01

    A bimetallic spacer means designed to be cooperatively associated with a nuclear fuel assembly and operative to resist the occurrence of in-reactor bowing of the nuclear fuel assembly. The subject bimetallic spacer means in accord with one embodiment of the invention includes a member formed, at least principally, of Zircaloy to which are attached a plurality of stainless steel strips. The latter stainless steel strips are located on the external surface of the Zircaloy member and with the major axis of each of the plurality of stainless steel strips extending substantially perpendicular to the major axis of the Zircaloy member. In accord with another embodiment of the invention, the subject bimetallic spacer means includes a member formed at least principally of Zircaloy to which a plurality of stainless steel strips are attached so as to be positioned thereon externally thereof and with the major axis of each of the plurality of stainless steel strips extending substantially parallel to the major axis of the Zircaloy member. In accord with a further embodiment of the invention, the stainless steel strips are attached to preselected members, each embodying at least a cladding of Zircaloy, which are located in the rows of fuel rods that define the perimeter of the fuel matrix of the nuclear fuel assembly. In each of the embodiments, the stainless steel strips during power production expand outwardly to a greater extent than do the members to which the stainless steel strips are attached, thereby forming stiff springs which abut against like bimetallic spacer means with which the other nuclear fuel assemblies are provided in a given nuclear reactor core to thus prevent the occurrence of in-reactor bowing of the nuclear fuel assemblies. Namely, the stainless steel strips expand laterally relative to the fuel assembly and thereby occupy the space adjacent to the external surface of the fuel assembly

  17. Impact of feed spacer and membrane modification by hydrophilic, bactericidal and biocidal coating on biofouling control

    KAUST Repository

    Araújo, Paula A.

    2012-06-01

    The influence of polydopamine- and polydopamine-. graft-poly(ethylene glycol)-coated feed spacers and membranes, copper-coated feed spacers, and commercially-available biostatic feed spacers on biofouling has been studied in membrane fouling simulators. Feed spacers and membranes applied in practical membrane filtration systems were used; biofouling development was monitored by feed channel pressure drop increase and biomass accumulation. Polydopamine and polydopamine-. g-PEG are hydrophilic surface modification agents expected to resist protein and bacterial adhesion, while copper feed spacer coatings and biocides infused in feed spacers are expected to restrict biological growth. Our studies showed that polydopamine and polydopamine-. g-PEG coatings on feed spacers and membranes, copper coatings on feed spacers, and a commercial biostatic feed spacer did not have a significant impact on feed channel pressure drop increase and biofilm accumulation as measured by ATP and TOC content. The studied spacer and membrane modifications were not effective for biofouling control; it is doubtful that feed spacer and membrane modification, in general, may be effective for biofouling control regardless of the type of applied coating. © 2012 Elsevier B.V.

  18. Preliminary analysis of the effect of the grid spacers on the reflood heat transfer

    International Nuclear Information System (INIS)

    Sugimoto, Jun; Murao, Yoshio

    1982-02-01

    The results are described about the preliminary analysis of the effect of the grid spacers on the heat transfer during reflood phase of a PWR LOCA. Experiments at JAERI and other facilities showed substantial heat transfer enhancement near the grid spacers. The heat transfer enhancement decreases with the distance from the grid spacers in the downstream region of the grid spacers. Several mechanisms are discussed about the heat transfer enhancement near the grid spacers. A model of a coalescence of the water droplets downstream the spacers is proposed based on the review of the experimental data. The heat transfer correlation for the saturated film boiling is utilized to quantify the heat transfer augmentation by the grid spacers. (author)

  19. Eddy current monitoring of spacers in coolant channel assemblies of nuclear reactor

    International Nuclear Information System (INIS)

    Bhole, V.M.; Rastogi, P.K.; Kulkarni, P.G.; Vijayaraghavan, R.

    1993-01-01

    An eddy current testing method has been standardised for monitoring spacer springs which are used in coolant channel assemblies of pressurised heavy water nuclear reactors (PHWRs). The standard bobbin coil probe used for monitoring the spacer spring detects only the location but does not monitor the tilt orientation and tilt angle of a tilted spacer spring. The knowledge of location along with the tilt orientation of the spacer spring greatly improves the performance of repositioning methods. A modified probe with angular windings has been developed in laboratory tests for monitoring the location as well as the tilt orientation of the spacer springs. Experimental results are presented showing excellent performance of the modified probe in monitoring the exact location as well as tilt orientation of a spacer spring. The modified probe has also been used successfully in the field during repositioning of spacer springs in PHWRs before commissioning. (Author)

  20. Development and characterization of 3D-printed feed spacers for spiral wound membrane systems

    KAUST Repository

    Siddiqui, Amber

    2016-01-02

    Feed spacers are important for the impact of biofouling on the performance of spiral-wound reverse osmosis (RO) and nanofiltration (NF) membrane systems. The objective of this study was to propose a strategy for developing, characterizing, and testing of feed spacers by numerical modeling, three-dimensional (3D) printing of feed spacers and experimental membrane fouling simulator (MFS) studies. The results of numerical modeling on the hydraulic behavior of various feed spacer geometries suggested that the impact of spacers on hydraulics and biofouling can be improved. A good agreement was found for the modeled and measured relationship between linear flow velocity and pressure drop for feed spacers with the same geometry, indicating that modeling can serve as first step in spacer characterization. An experimental comparison study of a feed spacer currently applied in practice and a 3D printed feed spacer with the same geometry showed (i) similar hydraulic behavior, (ii) similar pressure drop development with time and (iii) similar biomass accumulation during MFS biofouling studies, indicating that 3D printing technology is an alternative strategy for development of thin feed spacers with a complex geometry. Based on the numerical modeling results, a modified feed spacer with low pressure drop was selected for 3D printing. The comparison study of the feed spacer from practice and the modified geometry 3D printed feed spacer established that the 3D printed spacer had (i) a lower pressure drop during hydraulic testing, (ii) a lower pressure drop increase in time with the same accumulated biomass amount, indicating that modifying feed spacer geometries can reduce the impact of accumulated biomass on membrane performance. The combination of numerical modeling of feed spacers and experimental testing of 3D printed feed spacers is a promising strategy (rapid, low cost and representative) to develop advanced feed spacers aiming to reduce the impact of biofilm formation on

  1. On possible contribution of standing wave like spacer dynamics in polymer liquid crystals to quasi-elastic cold neutron scattering spectra

    International Nuclear Information System (INIS)

    Jecl, R.; Cvikl, B.

    1998-01-01

    The quasi-elastic cold neutron incoherent scattering law, QNS, for the assumed case of transversal standing wave type of motion of the linear chain a spacer-of the polyacrylate polymer liquid crystal, based upon the random walk of the particle between two perfectly potential barriers, is derived. The spacer protons are taken to vibrate (within the stationary plane) transversely to the line joining the oxygen atoms in a way where they are all simultaneously displaced in the same direction with amplitudes of the standing wave fundamental mode of the vibration excited. The calculated relevant incoherent scattering law is found to be a non-distinct function of the scattering vector Q, in the sense that the postulated dynamical effect of the spacer protons causes the peak value of the calculated incoherent scattering law, S(Q,ω), to remain constant throughout the experimentally accessible range of the scattering vector Q. It appears that, when the experimental resolution broadening effects is taken into account, the contribution of the postulated dynamical behavior to the measured QNS spectra might be small, particularly so, if dome additional motion of the scatters is present, and consequently the standing wave like spacer dynamics in polymer liquid crystals will be very difficult to be identified uniquely in the quasielastic neutron scattering experiments.(author)

  2. GENOMIC DNA-FINGERPRINTING OF CLINICAL HAEMOPHILUS-INFLUENZAE ISOLATES BY POLYMERASE CHAIN-REACTION AMPLIFICATION - COMPARISON WITH MAJOR OUTER-MEMBRANE PROTEIN AND RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM ANALYSIS

    NARCIS (Netherlands)

    VANBELKUM, A; DUIM, B; REGELINK, A; MOLLER, L; QUINT, W; VANALPHEN, L

    Non-capsulate strains of Haemophilus influenzae were genotyped by analysis of variable DNA segments obtained by amplification of genomic DNA with the polymerase chain reaction (PCR fingerprinting). Discrete fragments of 100-2000 bp were obtained. The reproducibility of the procedure was assessed by

  3. Effect of PEG biofunctional spacers and TAT peptide on dsRNA loading on gold nanoparticles

    International Nuclear Information System (INIS)

    Sanz, Vanesa; Conde, João; Hernández, Yulán; Baptista, Pedro V.; Ibarra, M. R.; Fuente, Jesús M. de la

    2012-01-01

    The surface chemistry of gold nanoparticles (AuNPs) plays a critical role in the self-assembly of thiolated molecules and in retaining the biological function of the conjugated biomolecules. According to the well-established gold–thiol interaction the undefined ionic species on citrate-reduced gold nanoparticle surface can be replaced with a self-assembled monolayer of certain thiolate derivatives and other biomolecules. Understanding the effect of such derivatives in the functionalization of several types of biomolecules, such as PEGs, peptides or nucleic acids, has become a significant challenge. Here, an approach to attach specific biomolecules to the AuNPs (∼14 nm) surface is presented together with a study of their effect in the functionalization with other specific derivatives. The effect of biofunctional spacers such as thiolated poly(ethylene glycol) (PEG) chains and a positive peptide, TAT, in dsRNA loading on AuNPs is reported. Based on the obtained data, we hypothesize that loading of oligonucleotides onto the AuNP surface may be controlled by ionic and weak interactions positioning the entry of the oligo through the PEG layer. We demonstrate that there is a synergistic effect of the TAT peptide and PEG chains with specific functional groups on the enhancement of dsRNA loading onto AuNPs.

  4. Effect of PEG biofunctional spacers and TAT peptide on dsRNA loading on gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Sanz, Vanesa; Conde, Joao; Hernandez, Yulan [Universidad de Zaragoza, Instituto de Nanociencia de Aragon (Spain); Baptista, Pedro V. [Universidade Nova de Lisboa, Departamento de Ciencias da Vida, Faculdade de Ciencias e Tecnologia, Centro de Investigacao em Genetica Molecular Humana (Portugal); Ibarra, M. R.; Fuente, Jesus M. de la, E-mail: jmfuente@unizar.es [Universidad de Zaragoza, Instituto de Nanociencia de Aragon (Spain)

    2012-06-15

    The surface chemistry of gold nanoparticles (AuNPs) plays a critical role in the self-assembly of thiolated molecules and in retaining the biological function of the conjugated biomolecules. According to the well-established gold-thiol interaction the undefined ionic species on citrate-reduced gold nanoparticle surface can be replaced with a self-assembled monolayer of certain thiolate derivatives and other biomolecules. Understanding the effect of such derivatives in the functionalization of several types of biomolecules, such as PEGs, peptides or nucleic acids, has become a significant challenge. Here, an approach to attach specific biomolecules to the AuNPs ({approx}14 nm) surface is presented together with a study of their effect in the functionalization with other specific derivatives. The effect of biofunctional spacers such as thiolated poly(ethylene glycol) (PEG) chains and a positive peptide, TAT, in dsRNA loading on AuNPs is reported. Based on the obtained data, we hypothesize that loading of oligonucleotides onto the AuNP surface may be controlled by ionic and weak interactions positioning the entry of the oligo through the PEG layer. We demonstrate that there is a synergistic effect of the TAT peptide and PEG chains with specific functional groups on the enhancement of dsRNA loading onto AuNPs.

  5. An insulating grid spacer for large-area MICROMEGAS chambers

    CERN Document Server

    Bernard, D; D'Enterria, D G; Le Guay, M; Martínez, G; Mora, M J; Pichot, P; Roy, D; Schutz, Y; Gandi, A; De Oliveira, R

    2002-01-01

    We present an original design for large area gaseous detectors based on the MICROMEGAS technology. This technology incorporates an insulating grid, sandwiched between the micro-mesh and the anode-pad plane, which provides an uniform 200 $\\mu$m amplification gap. The uniformity of the amplification gap thickness has been verified under several experimental conditions. The gain performances of the detector are presented and compared to the values obtained with detectors using cylindrical micro spacers. The new design presents several technical and financial advantages.

  6. Spacer grid with mixing blades for nuclear fuel assembly

    International Nuclear Information System (INIS)

    Noailly, J.

    1986-01-01

    The spacer grid for nuclear fuel assembly has two sets of intersecting metal plates provided with blades and defining cells. The plates are fitted only with half-blades associated with a single grid opening. The half-blades of adjacent cells are arranged at 90deg C to each other and each plate has at most one half-blade at each corner of a cell. The invention concerns fuel assemblies of pressurized water reactors. The blades arranged on a single side of the plate provide a good hydraulic uniformity. The invention provides a uniform distribution of blades (and thus of absorbing material in each hydraulic cell) [fr

  7. Tube spacer grid for a heat-exchanger tube bundle

    International Nuclear Information System (INIS)

    Scheidl, H.

    1976-01-01

    A tube spacer grid for a heat-exchanger tube bundle is formed by an annular grid frame having a groove formed in its inner surface in which the interspaced grid bars have their ends positioned and held in interspaced relationship by short sections of tubes passed through holes axially formed in the grid frame so that the tubes are positioned between the ends of the grid bars in the grooves. The tube sections may be cut from the same tubes used to form the tube bundle. 5 claims, 3 drawing figures

  8. In vitro microbiologic evaluation of PTFE and cotton as spacer materials.

    Science.gov (United States)

    Paranjpe, Avina; Jain, Sumita; Alibhai, Karim J; Wadhwani, Chandur P; Darveau, Richard P; Johnson, James D

    2012-09-01

    To microbiologically evaluate the efficacy of cotton and polytetrafluoroethylene (PTFE) tape used as spacer materials. Twenty-six extracted human molars were restored using either cotton or PTFE tape as spacers under a standardized provisional restorative material (Cavit). The teeth were incubated for 7 days in a culture of Streptococcus gordonii or in liquid media alone. The spacers were removed and tested for bacterial contamination. The access cavities were also evaluated for bacterial contamination. Nine of 10 teeth with cotton spacers and one of 10 teeth with PTFE spacers were positive for S gordonii growth. The nine teeth in the cotton group also showed contamination of the access cavities. Even under optimal conditions, cotton spacers may cause leakage into the access cavities. Cotton fibers may serve as a route for bacterial contamination of the access cavities and root canal space. In contrast, PTFE tape did not provide an avenue for bacterial contamination.

  9. A technical report on the evaluation of the integrity for the TIG welded spacer grid

    International Nuclear Information System (INIS)

    Song, Kee Nam; Yoo, Ho Sik; Lww, Chang Woo

    1994-07-01

    The spacer grid, which supports fuel rods, guide thimble and instrumentation tube, is classified into two types according to their strap material,.ie. inconel and zircaloy spacer grid. KOFA fuel of 14 x 14 and 17 x 17 type has seven and eight spacer grid respectively. Zircaloy spacer grid is assembled by straps whose cross points are welded by TIG welding method. This technical report provides to give some information about structure and function of the spacer grid and the basis and characteristic of the TIG welding method. A series of test which is conducted to evaluate the integrity of TIG welded zircaloy spacer grid and their results have been also studied. (Author) 18 refs., 23 figs., 3 tabs

  10. A technical report on the evaluation of the integrity for the TIG welded spacer grid

    Energy Technology Data Exchange (ETDEWEB)

    Song, Kee Nam; Yoo, Ho Sik; Lww, Chang Woo [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1994-07-01

    The spacer grid, which supports fuel rods, guide thimble and instrumentation tube, is classified into two types according to their strap material,.ie. inconel and zircaloy spacer grid. KOFA fuel of 14 x 14 and 17 x 17 type has seven and eight spacer grid respectively. Zircaloy spacer grid is assembled by straps whose cross points are welded by TIG welding method. This technical report provides to give some information about structure and function of the spacer grid and the basis and characteristic of the TIG welding method. A series of test which is conducted to evaluate the integrity of TIG welded zircaloy spacer grid and their results have been also studied. (Author) 18 refs., 23 figs., 3 tabs.

  11. Transcriptional regulator-mediated activation of adaptation genes triggers CRISPR de novo spacer acquisition

    DEFF Research Database (Denmark)

    Liu, Tao; Li, Yingjun; Wang, Xiaodi

    2015-01-01

    Acquisition of de novo spacer sequences confers CRISPR-Cas with a memory to defend against invading genetic elements. However, the mechanism of regulation of CRISPR spacer acquisition remains unknown. Here we examine the transcriptional regulation of the conserved spacer acquisition genes in Type I......, it was demonstrated that the transcription level of csa1, cas1, cas2 and cas4 was significantly enhanced in a csa3a-overexpression strain and, moreover, the Csa1 and Cas1 protein levels were increased in this strain. Furthermore, we demonstrated the hyperactive uptake of unique spacers within both CRISPR loci...... in the presence of the csa3a overexpression vector. The spacer acquisition process is dependent on the CCN PAM sequence and protospacer selection is random and non-directional. These results suggested a regulation mechanism of CRISPR spacer acquisition where a single transcriptional regulator senses the presence...

  12. Influence of the spacer dielectric processes on PMOS junction properties

    International Nuclear Information System (INIS)

    Morin, Pierre; Wacquant, Francois; Juhel, Marc; Laviron, Cyrille; Lenoble, D.

    2005-01-01

    In this paper, the interaction observed in PMOS transistor between the boron lightly doped drain (LDD) extensions and the spacer oxide and nitride dielectrics have been studied, with a simple experimental methodology. Low thermal budget oxide obtained by sub-atmospheric chemical vapor deposition (SACVD) and nitride deposited by plasma process have been evaluated as spacer layers. The influence of the oxide liner hydrogen content is shown to be critical for the p type shallow junction. Indeed, during the activation anneal, hydrogen content increases the boron out diffusion from the extension into the oxide liner and yield to a significant dose loss in this area. Nitride porosity has also been studied. A lower boron dose loss is observed with a porous layer because hydrogen can degas out significantly from the oxide, during anneal, through the porous nitride film. These results confirm the model of boron out diffusion based on oxide hydrogen content proposed by Kohli. Finally, a boron diffusion mechanism driven by chemistry and enhanced by hydrogen defects is proposed

  13. Single-electron transistors fabricated with sidewall spacer patterning

    Science.gov (United States)

    Park, Byung-Gook; Kim, Dae Hwan; Kim, Kyung Rok; Song, Ki-Whan; Lee, Jong Duk

    2003-09-01

    We have implemented a sidewall spacer patterning method for novel dual-gate single-electron transistor (DGSET) and metal-oxide-semiconductor-based SET (MOSET) based on the uniform SOI wire, using conventional lithography and processing technology. A 30 nm wide silicon quantum wire is defined by a sidewall spacer patterning method, and depletion gates for two tunnel junctions of the DGSET are formed by the doped polycrystalline silicon sidewall. The fabricated DGSET and MOSET show clear single-electron tunneling phenomena at liquid nitrogen temperature and insensitivity of the Coulomb oscillation period to gate bias conditions. On the basis of the phase control capability of the sidewall depletion gates, we have proposed a complementary self-biasing method, which enables the SET/CMOS hybrid multi-valued logic (MVL) to operate perfectly well at high temperature, where the peak-to-valley current ratio of Coulomb oscillation severely decreases. The suggested scheme is evaluated by SPICE simulation with an analytical DGSET model, and it is confirmed that even DGSETs with a large Si island can be utilized efficiently in the multi-valued logic.

  14. Packaging design criteria modified fuel spacer burial box. Revision 1

    International Nuclear Information System (INIS)

    Stevens, P.F.

    1994-01-01

    Various Hanford facilities must transfer large radioactively contaminated items to burial/storage. Presently, there are eighteen Fuel Spacer Burial Boxes (FSBBs) available on the Hanford Site for transport of such items. Previously, the FSBBS were transported from a rail car to the burial trench via a drag-off operation. To allow for the lifting of the boxes into the burial trench, it will be necessary to improve the packagings lifting attachments and provide structural reinforcement. Additional safety improvements to the packaging system will be provided by the addition of a positive closure system and package ventilation. FSBBs that are modified in such a manner are referred to as Modified Fuel Spacer Burial Boxes (MFSBs). The criteria provided by this PDC will be used to demonstrate that the transfer of the MFSB will provide an equivalent degree of safety as would be provided by a package meeting offsite transportation requirements. This fulfills the onsite transportation safety requirements implemented in WHC-CM-2-14, Hazardous Material Packaging and Shipping. A Safety Analysis Report for Packaging (SARP) will be prepared to evaluate the safety of the transfer operation. Approval of the SARP is required to authorize transfer. Criteria are also established to ensure burial requirements are met

  15. A Study on Structural Strength of Irradiated Spacer Grid for PWR Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Y. G.; Baek, S. J.; Kim, D. S.; Yoo, B. O.; Ahn, S. B.; Chun, Y. B. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, J. I.; Kim, Y. H.; Lee, J. J. [KEPCO NF, Daejeon (Korea, Republic of)

    2014-10-15

    A fuel assembly consists of an array of fuel rods, spacer grids, guide thimbles, instrumentation tubes, and top and bottom nozzles. In PWR (Pressurized light Water Reactor) fuel assemblies, the spacer grids support the fuel rods by the friction forces between the fuel rods and springs/dimples. Under irradiation, the spacer grids supporting the fuel rods absorb vibration impacts due to the reactor coolant flow, and also bear static and dynamic loads during operation inside the nuclear reactor and transportation for spent fuel storage. Thus, it is important to understand the characteristics of deformation behavior and the change in structural strength of an irradiated spacer grid.. In the present study, the static compression test of a spacer grid was conducted to investigate the structural strength of the irradiated spacer grid in a hot cell at IMEF (Irradiated Materials Examination Facility) of KAERI. To evaluate the structural strength of an irradiated spacer grid, hot cell tests were carried out at IMEF of KAERI. The fuel assembly was dismantled and the irradiated spacer grid was obtained for the compression test. The apparatus for measuring the compression strength of the irradiated spacer grid was developed and installed successfully in the hot cell.

  16. Nanoparticle-Based Brachytherapy Spacers for Delivery of Localized Combined Chemoradiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Rajiv, E-mail: r.kumar@neu.edu [Nanomedicine Science and Technology Center, Northeastern University, Boston, Massachusetts (United States); Department of Radiation Oncology, Brigham and Women' s Hospital, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts (United States); Belz, Jodi [Nanomedicine Science and Technology Center, Northeastern University, Boston, Massachusetts (United States); Markovic, Stacey [Department of Electrical and Computer Engineering, Northeastern University, Boston, Massachusetts (United States); Jadhav, Tej; Fowle, William [Nanomedicine Science and Technology Center, Northeastern University, Boston, Massachusetts (United States); Niedre, Mark [Department of Electrical and Computer Engineering, Northeastern University, Boston, Massachusetts (United States); Cormack, Robert; Makrigiorgos, Mike G. [Department of Radiation Oncology, Brigham and Women' s Hospital, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts (United States); Sridhar, Srinivas [Nanomedicine Science and Technology Center, Northeastern University, Boston, Massachusetts (United States); Department of Radiation Oncology, Brigham and Women' s Hospital, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts (United States)

    2015-02-01

    Purpose: In radiation therapy (RT), brachytherapy-inert source spacers are commonly used in clinical practice to achieve high spatial accuracy. These implanted devices are critical technical components of precise radiation delivery but provide no direct therapeutic benefits. Methods and Materials: Here we have fabricated implantable nanoplatforms or chemoradiation therapy (INCeRT) spacers loaded with silica nanoparticles (SNPs) conjugated containing a drug, to act as a slow-release drug depot for simultaneous localized chemoradiation therapy. The spacers are made of poly(lactic-co-glycolic) acid (PLGA) as matrix and are physically identical in size to the commercially available brachytherapy spacers (5 mm × 0.8 mm). The silica nanoparticles, 250 nm in diameter, were conjugated with near infrared fluorophore Cy7.5 as a model drug, and the INCeRT spacers were characterized in terms of size, morphology, and composition using different instrumentation techniques. The spacers were further doped with an anticancer drug, docetaxel. We evaluated the in vivo stability, biocompatibility, and biodegradation of these spacers in live mouse tissues. Results: The electron microscopy studies showed that nanoparticles were distributed throughout the spacers. These INCeRT spacers remained stable and can be tracked by the use of optical fluorescence. In vivo optical imaging studies showed a slow diffusion of nanoparticles from the spacer to the adjacent tissue in contrast to the control Cy7.5-PLGA spacer, which showed rapid disintegration in a few days with a burst release of Cy7.5. The docetaxel spacers showed suppression of tumor growth in contrast to control mice over 16 days. Conclusions: The imaging with the Cy7.5 spacer and therapeutic efficacy with docetaxel spacers supports the hypothesis that INCeRT spacers can be used for delivering the drugs in a slow, sustained manner in conjunction with brachytherapy, in contrast to the rapid clearance of the drugs when

  17. Research report on development of spacer grid strap for AFA 3G fuel assembly

    International Nuclear Information System (INIS)

    Ye Yuandong

    2004-11-01

    The current development and tendency for fuel assemblies being of low leakage, high burn-up and long cycle fuel reload in the world are presented, and the necessity and feasibility to develop the spacer grid for high burn-up fuel assembly are elaborated. Considering all the activities in implementing of spacer grid and the technical difficulties in machining of tools, the major technological processes are introduced; the research program and the approaches to develop the spacer grid while research targets and overall schedule are defined and some key technical points and applicable practices are discussed. Finally the requirements and the conditions necessary for developing of spacer grid are proposed. (authors)

  18. Nanoparticle-Based Brachytherapy Spacers for Delivery of Localized Combined Chemoradiation Therapy

    International Nuclear Information System (INIS)

    Kumar, Rajiv; Belz, Jodi; Markovic, Stacey; Jadhav, Tej; Fowle, William; Niedre, Mark; Cormack, Robert; Makrigiorgos, Mike G.; Sridhar, Srinivas

    2015-01-01

    Purpose: In radiation therapy (RT), brachytherapy-inert source spacers are commonly used in clinical practice to achieve high spatial accuracy. These implanted devices are critical technical components of precise radiation delivery but provide no direct therapeutic benefits. Methods and Materials: Here we have fabricated implantable nanoplatforms or chemoradiation therapy (INCeRT) spacers loaded with silica nanoparticles (SNPs) conjugated containing a drug, to act as a slow-release drug depot for simultaneous localized chemoradiation therapy. The spacers are made of poly(lactic-co-glycolic) acid (PLGA) as matrix and are physically identical in size to the commercially available brachytherapy spacers (5 mm × 0.8 mm). The silica nanoparticles, 250 nm in diameter, were conjugated with near infrared fluorophore Cy7.5 as a model drug, and the INCeRT spacers were characterized in terms of size, morphology, and composition using different instrumentation techniques. The spacers were further doped with an anticancer drug, docetaxel. We evaluated the in vivo stability, biocompatibility, and biodegradation of these spacers in live mouse tissues. Results: The electron microscopy studies showed that nanoparticles were distributed throughout the spacers. These INCeRT spacers remained stable and can be tracked by the use of optical fluorescence. In vivo optical imaging studies showed a slow diffusion of nanoparticles from the spacer to the adjacent tissue in contrast to the control Cy7.5-PLGA spacer, which showed rapid disintegration in a few days with a burst release of Cy7.5. The docetaxel spacers showed suppression of tumor growth in contrast to control mice over 16 days. Conclusions: The imaging with the Cy7.5 spacer and therapeutic efficacy with docetaxel spacers supports the hypothesis that INCeRT spacers can be used for delivering the drugs in a slow, sustained manner in conjunction with brachytherapy, in contrast to the rapid clearance of the drugs when

  19. Cervical interfacet spacers and maintenance of cervical lordosis.

    Science.gov (United States)

    Tan, Lee A; Straus, David C; Traynelis, Vincent C

    2015-05-01

    OBJECT The cervical interfacet spacer (CIS) is a relatively new technology that can increase foraminal height and area by facet distraction. These offer the potential to provide indirect neuroforaminal decompression while simultaneously enhancing fusion potential due to the relatively large osteoconductive surface area and compressive forces exerted on the grafts. These potential benefits, along with the relative ease of implantation during posterior cervical fusion procedures, make the CIS an attractive adjuvant in the management of cervical pathology. One concern with the use of interfacet spacers is the theoretical risk of inducing iatrogenic kyphosis. This work tests the hypothesis that interfacet spacers are associated with loss of cervical lordosis. METHODS Records from patients undergoing posterior cervical fusion at Rush University Medical Center between March 2011 and December 2012 were reviewed. The FacetLift CISs were used in all patients. Preoperative and postoperative radiographic data were reviewed and the Ishihara indices and cervical lordotic angles were measured and recorded. Statistical analyses were performed using STATA software. RESULTS A total of 64 patients were identified in whom 154 cervical levels were implanted with machined allograft interfacet spacers. Of these, 15 patients underwent anterior-posterior fusions, 4 underwent anterior-posterior-anterior fusions, and the remaining 45 patients underwent posterior-only fusions. In the 45 patients with posterior-only fusions, a total of 110 levels were treated with spacers. There were 14 patients (31%) with a single level treated, 16 patients (36%) with two levels treated, 5 patients (11%) with three levels treated, 5 patients (11%) with four levels treated, 1 patient (2%) with five levels treated, and 4 patients (9%) with six levels treated. Complete radiographic data were available in 38 of 45 patients (84%). On average, radiographic follow-up was obtained at 256.9 days (range 48-524 days

  20. Falling chains

    OpenAIRE

    Wong, Chun Wa; Yasui, Kosuke

    2005-01-01

    The one-dimensional fall of a folded chain with one end suspended from a rigid support and a chain falling from a resting heap on a table is studied. Because their Lagrangians contain no explicit time dependence, the falling chains are conservative systems. Their equations of motion are shown to contain a term that enforces energy conservation when masses are transferred between subchains. We show that Cayley's 1857 energy nonconserving solution for a chain falling from a resting heap is inco...

  1. Telomere Length and Mortality

    DEFF Research Database (Denmark)

    Kimura, Masayuki; Hjelmborg, Jacob V B; Gardner, Jeffrey P

    2008-01-01

    Leukocyte telomere length, representing the mean length of all telomeres in leukocytes, is ostensibly a bioindicator of human aging. The authors hypothesized that shorter telomeres might forecast imminent mortality in elderly people better than leukocyte telomere length. They performed mortality...

  2. Measurement and CFD calculation of spacer loss coefficient for a tight-lattice fuel bundle

    International Nuclear Information System (INIS)

    In, Wang Kee; Shin, Chang Hwan; Kwack, Young Kyun; Lee, Chi Young

    2015-01-01

    Highlights: • Experiment and CFD analysis evaluated the pressure drop in a spacer grid. • The measurement and CFD errors for the spacer loss coefficient were estimated. • The spacer loss coefficient for the dual-cooled annular fuel bundle was determined. • The CFD prediction agrees with the measured spacer loss coefficient within 8%. - Abstract: An experiment and computational fluid dynamics (CFD) analysis were performed to evaluate the pressure drop in a spacer grid for a dual-cooled annular fuel (DCAF) bundle. The DCAF bundle for the Korean optimum power reactor (OPR1000) is a 12 × 12 tight-lattice rod array with a pitch-to-diameter ratio of 1.08 owing to a larger outer diameter of the annular fuel rod. An experiment was conducted to measure the pressure drop in spacer grid for the DCAF bundle. The test bundle is a full-size 12 × 12 rod bundle with 11 spacer grid. The test condition covers a Reynolds number range of 2 × 10 4 –2 × 10 5 by changing the temperature and flow rate of water. A CFD analysis was also performed to predict the pressure drop through a spacer grid using the full-size and partial bundle models. The pressure drop and loss coefficient of a spacer grid were predicted and compared with the experimental results. The CFD predictions of spacer pressure drop and loss coefficient agree with the measured values within 8%. The spacer loss coefficient for the DCAF bundle is estimated to be approximately 1.50 at a nominal operating condition of OPR1000, i.e., Re = 4 × 10 5

  3. CFD modeling of turbulent mixing through vertical pressure tube type boiling water reactor fuel rod bundles with spacer-grids

    Science.gov (United States)

    Verma, Shashi Kant; Sinha, S. L.; Chandraker, D. K.

    2018-05-01

    Numerical simulation has been carried out for the study of natural mixing of a Tracer (Passive scalar) to describe the development of turbulent diffusion in an injected sub-channel and, afterwards on, cross-mixing between adjacent sub-channels. In this investigation, post benchmark evaluation of the inter-subchannel mixing was initiated to test the ability of state-of-the-art Computational Fluid Dynamics (CFD) codes to numerically predict the important turbulence parameters downstream of a ring type spacer grid in a rod-bundle. A three-dimensional Computational Fluid Dynamics (CFD) tool (STAR-CCM+) was used to model the single phase flow through a 30° segment or 1/12th of the cross segment of a 54-rod bundle with a ring shaped spacer grid. Polyhedrons were used to discretize the computational domain, along with prismatic cells near the walls, with an overall mesh count of 5.2 M cell volumes. The Reynolds Stress Models (RSM) was tested because of RSM accounts for the turbulence anisotropy, to assess their capability in predicting the velocities as well as mass fraction of potassium nitrate measured in the experiment. In this way, the line probes are located in the different position of subchannels which could be used to characterize the progress of the mixing along the flow direction, and the degree of cross-mixing assessed using the quantity of tracer arriving in the neighbouring sub-channels. The predicted dimensionless mixing scalar along the length, however, was in good agreement with the measurements downstream of spacers.

  4. The influence of the preliminary garter spring spacer simulator clamping force in the pressure tube spacer -calandria tube hook-up simulator aging behaviour

    International Nuclear Information System (INIS)

    Gyongyosi, T.; Deloreanu, G.; Puiu, D.; Corbescu, B.; Anghel, N.; Dinu, E.

    2016-01-01

    The garter spring spacer is a specially constructed torsion spring used to fit-out the CANDU 6 fuel channel. The pressure tube ageing decreases the gap to the calandria tube. Continuous gap decrease directly affects the garter spring spacers behavior during fuel channel assembly operation. The preliminary clamping force value of the garter spring spacer assembly is important for its ageing behavior. This paper briefly describes the experimental technological facilities used for conducted the experiments and highlights some of the important moments during an experiment carried out in laboratory conditions, without using pressurized boiled water and irradiation working conditions. The results analysis and some conclusions are outlined at the end, pointing out that a garter spring spacer preliminary clamping force increase reduces the vibration response signal amplitude, and does not lead to its relaxation. The paper is dedicated to specialists working in research and technological engineering. (authors)

  5. Unit and internal chain profiles of maca amylopectin.

    Science.gov (United States)

    Zhang, Ling; Li, Guantian; Yao, Weirong; Zhu, Fan

    2018-03-01

    Unit chain length distributions of amylopectin and its φ, β-limit dextrins, which reflect amylopectin internal structure from three maca starches, were determined by high-performance anion-exchange chromatography with pulsed amperometric detection after debranching, and the samples were compared with maize starch. The amylopectins exhibited average chain lengths ranging from 16.72 to 17.16, with ranges of total internal chain length, external chain length, and internal chain length of the maca amylopectins at 12.49 to 13.68, 11.24 to 11.89, and 4.27 to 4.48. The average chain length, external chain length, internal chain length, and total internal chain length were comparable in three maca amylopectins. Amylopectins of the three maca genotypes studied here presented no significant differences in their unit chain length profiles, but did show significant differences in their internal chain profiles. Additional genetic variations between different maca genotypes need to be studied to provide unit- and internal chain profiles of maca amylopectin. Copyright © 2017. Published by Elsevier Ltd.

  6. Analysis of sequence diversity through internal transcribed spacers and simple sequence repeats to identify Dendrobium species.

    Science.gov (United States)

    Liu, Y T; Chen, R K; Lin, S J; Chen, Y C; Chin, S W; Chen, F C; Lee, C Y

    2014-04-08

    The Orchidaceae is one of the largest and most diverse families of flowering plants. The Dendrobium genus has high economic potential as ornamental plants and for medicinal purposes. In addition, the species of this genus are able to produce large crops. However, many Dendrobium varieties are very similar in outward appearance, making it difficult to distinguish one species from another. This study demonstrated that the 12 Dendrobium species used in this study may be divided into 2 groups by internal transcribed spacer (ITS) sequence analysis. Red and yellow flowers may also be used to separate these species into 2 main groups. In particular, the deciduous characteristic is associated with the ITS genetic diversity of the A group. Of 53 designed simple sequence repeat (SSR) primer pairs, 7 pairs were polymorphic for polymerase chain reaction products that were amplified from a specific band. The results of this study demonstrate that these 7 SSR primer pairs may potentially be used to identify Dendrobium species and their progeny in future studies.

  7. Chain networking revealed by molecular dynamics simulation

    Science.gov (United States)

    Zheng, Yexin; Tsige, Mesfin; Wang, Shi-Qing

    Based on Kremer-Grest model for entangled polymer melts, we demonstrate how the response of a polymer glass depends critically on the chain length. After quenching two melts of very different chain lengths (350 beads per chain and 30 beads per chain) into deeply glassy states, we subject them to uniaxial extension. Our MD simulations show that the glass of long chains undergoes stable necking after yielding whereas the system of short chains is unable to neck and breaks up after strain localization. During ductile extension of the polymer glass made of long chain significant chain tension builds up in the load-bearing strands (LBSs). Further analysis is expected to reveal evidence of activation of the primary structure during post-yield extension. These results lend support to the recent molecular model 1 and are the simulations to demonstrate the role of chain networking. This work is supported, in part, by a NSF Grant (DMR-EAGER-1444859)

  8. Magnetic decoupling of ferromagnetic metals through a graphene spacer

    Energy Technology Data Exchange (ETDEWEB)

    Grimaldi, I.; Papagno, M. [Dipartimento di Fisica, Universitá della Calabria, Arcavacata di Rende (CS), 87036 (Italy); Ferrari, L. [Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, Roma I-00133 (Italy); Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Trieste (Italy); Sheverdyaeva, P.M.; Mahatha, S.K. [Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Trieste (Italy); Pacilé, D., E-mail: daniela.pacile@fis.unical.it [Dipartimento di Fisica, Universitá della Calabria, Arcavacata di Rende (CS), 87036 (Italy); Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Trieste (Italy); Carbone, C. [Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Trieste (Italy)

    2017-03-15

    We study the magnetic coupling between different ferromagnetic metals (FMs) across a graphene (G) layer, and the role of graphene as a thin covalent spacer. Starting with G grown on a FM substrate (Ni or Co), we deposited on top at room temperature several FM metals (Fe, Ni, Co). By measuring the dichroic effect of 3p photoemission lines we detect the magnetization of the substrate and the sign of the exchange coupling in FM overlayer at room temperature. We show that the G layer magnetically decouples the FM metals. - Highlights: • The magnetic coupling between ferromagnets mediated by graphene is studied. • To this end, the linear dichroic effect in 3p photoemission lines is employed. • For selected junctions no magnetic coupling is attained through graphene. • Graphene inhibits the magnetic alignment that normally occurs between ferromagnets.

  9. Dark current of organic heterostructure devices with insulating spacer layers

    Science.gov (United States)

    Yin, Sun; Nie, Wanyi; Mohite, Aditya D.; Saxena, Avadh; Smith, Darryl L.; Ruden, P. Paul

    2015-03-01

    The dark current density at fixed voltage bias in donor/acceptor organic planar heterostructure devices can either increase or decrease when an insulating spacer layer is added between the donor and acceptor layers. The dominant current flow process in these systems involves the formation and subsequent recombination of an interfacial exciplex state. If the exciplex formation rate limits current flow, the insulating interface layer can increase dark current whereas, if the exciplex recombination rate limits current flow, the insulating interface layer decreases dark current. We present a device model to describe this behavior and illustrate it experimentally for various donor/acceptor systems, e.g. P3HT/LiF/C60.

  10. Effect of NiAl underlayer and spacer on magnetoresistance of current-perpendicular-to-plane spin valves using Co2Mn(Ga0.5Sn0.5) Heusler alloy

    International Nuclear Information System (INIS)

    Hase, N.; Nakatani, T.M.; Kasai, S.; Takahashi, Y.K.; Furubayashi, T.; Hono, K.

    2012-01-01

    We investigated the effect of a NiAl underlayer and spacer on magnetoresistive (MR) properties in current-perpendicular-to-plane spin valves (CPP-SVs) using Co 2 Mn(Ga 0.5 Sn 0.5 ) (CMGS) Heusler alloy ferromagnetic layers. The usage of a NiAl underlayer allowed a high temperature annealing for the L2 1 ordering of the bottom CMGS layer, giving rise to a MR ratio of 10.2% at room temperature. We found that the usage of a NiAl spacer layer also improved the tolerance of the multilayer structure against thermal delamination, which allowed annealing to induce the L2 1 structure in both the bottom and top CMGS layers. However, the short spin diffusion length of NiAl resulted in a lower MR ratio compared to that obtained using a Ag spacer. Transmission electron microscopy of the multilayer structure of CPP-SVs showed that the atomically flat layered structure was maintained after the annealing. - Highlights: → CPP spin valves using Co 2 Mn(Ga 0.5 Sn 0.5 ) ferromagnetic layers with a new underlayer material. → NiAl underlayer and spacer improve the thermal tolerance of the spin valve structure. → NiAl underlayer improves MR ratio compared to Ag because of higher annealing temperature. → NiAl spacer degrades MR ratios compared to Ag because of short spin diffusion length. → Potential of heat resistant underlayer and spacer layer for CPP-SV using Heusler alloy.

  11. Optimized spacer layer thickness for plasmonic-induced enhancement of photocurrent in a-Si:H

    Energy Technology Data Exchange (ETDEWEB)

    Saleh, Z. M., E-mail: zaki.saleh@aauj.edu, E-mail: zakimsaleh@yahoo.com; Nasser, H.; Özkol, E.; Günöven, M.; Abak, K. [Middle East Technical University, Center for Solar Energy Research and Applications (GÜNAM) (Turkey); Canli, S. [Middle East Technical University, Central Laboratory (Turkey); Bek, A.; Turan, R. [Middle East Technical University, Center for Solar Energy Research and Applications (GÜNAM) (Turkey)

    2015-10-15

    Plasmonic interfaces consisting of silver nanoparticles of different sizes (50–100 nm) have been processed by the self-assembled dewetting technique and integrated to hydrogenated amorphous silicon (a-Si:H) using SiNx spacer layers to investigate the dependence of optical trapping enhancement on spacer layer thickness through the enhancements in photocurrent. Samples illuminated from the a-Si:H side exhibit a localized surface plasmon resonance (LSPR) that is red-shifted with the increasing particle size and broadened into the red with the increasing spacer layer thickness. The photocurrent measured in a-Si:H is not only consistent with the red-shift and broadening of the LSPR, but exhibits critical dependence on the spacer layer thickness also. The samples with plasmonic interfaces and a SiNx spacer layer exhibit appreciable enhancement of photocurrent compared with flat a-Si:H reference depending on the size of the Ag nanoparticle. Simulations conducted on one-dimensional square structures exhibit electric fields that are localized near the plasmonic structures but extend appreciably into the higher refractive index a-Si:H. These simulations produce a clear red-shift and broadening of extinction spectra for all spacer layer thicknesses and predict an enhancement in photocurrent in agreement with experimental results. The spectral dependence of photocurrent for six plasmonic interfaces with different Ag nanoparticle sizes and spacer layer thicknesses are correlated with the optical spectra and compared with the simulations to predict an optimal spacer layer thickness.

  12. Ertapenem Articulating Spacer for the Treatment of Polymicrobial Total Knee Arthroplasty Infection

    Directory of Open Access Journals (Sweden)

    Dragan Radoicic

    2016-01-01

    Full Text Available Introduction. Periprosthetic joint infections (PJIs are the primary cause of early failure of the total knee arthroplasty (TKA. Polymicrobial TKA infections are often associated with a higher risk of treatment failure. The aim of the study was to assess the efficacy of ertapenem loaded spacers in the treatment of polymicrobial PJI. Methods. There were 18 patients enrolled; nine patients with polymicrobial PJI treated with ertapenem loaded articulating spacers were compared to the group of 9 patients treated with vancomycin or ceftazidime loaded spacers. Results. Successful reimplantation with revision implants was possible in 66.67%. Ertapenem spacers were used in 6 cases in primary two-stage procedure and in 3 cases in secondary spacer exchange. Successful infection eradication was achieved in all cases; final reimplantation with revision knee arthroplasty implants was possible in 6 cases. Conclusion. Ertapenem can be successfully used as antimicrobial addition to the cement spacers in two-stage revision treatment of polymicrobial PJIs. However, this type of spacer may also be useful in the treatment of infections caused by monomicrobial extended spectrum beta-lactamases producing gram-negative bacilli. Further clinical studies are required to evaluate the efficacy and safety of ertapenem spacers in the treatment of polymicrobial and monomicrobial PJIs.

  13. Boiling transition phenomenon in BWR fuel assemblies effect of fuel spacer shape on critical power

    International Nuclear Information System (INIS)

    Yamamoto, Yasushi; Morooka, Shin-ichi; Mitsutake, Toru; Yokobori, Seiichi; Kimura, Jiro.

    1996-01-01

    A thorough understanding of the thermal-hydraulic phenomena near fuel spacer is necessary for the accurate prediction of the critical power of BWR fuel assemblies, and is thus essential for effective developments of a new BWR fuel assembly. The main purpose of this study is to develop an accurate method for predicting the effect of spacer shapes on critical power. Tests have been conducted under actual BWR operating conditions, using an annulus flow channel consisting of a heated rod and circular-tube channel, and BWR simulated 4x4 rod bundles with heater rods unheated just upsteam of spacer. The effect of spacer shapes on critical power was predicted analytically based on the droplet deposition rate estimation. The droplet deposition rate for different spacer shapes was calculated using a single-phase flow model. The prediction results were compared with the test results for the annulus flow channel using ring-type spacers. Analytical results of critical power agreed with measured critical power from point of the effects of changes in the rod-spacer clearance and the spacer thickness on critical power. (author)

  14. Modeling the effect of spacers and biofouling on forward osmosis performance

    KAUST Repository

    Mosqueira Santillá n, Marí a José

    2014-01-01

    and operational conditions. For this, a two dimensional numerical model for FO systems was developed using computational fluid dynamics (CFD). This model allowed the evaluation of the impact of (i) spacers and (ii) biofilm, and (iii) the combined impact of spacers

  15. Solution-processed organic tandem solar cells with embedded optical spacers

    NARCIS (Netherlands)

    Hadipour, Afshin; de Boer, Bert; Blom, Paul W. M.

    2007-01-01

    We demonstrate a solution-processed polymer tandem solar cell in which the two photoactive single cells are separated by an optical spacer. The use of an optical spacer allows for an independent optimization of both the electronic and optical properties of the tandem cell. The optical transmission

  16. Effect of plastic spacer handling on salbutamol lung deposition in asthmatic children

    DEFF Research Database (Denmark)

    Lipworth, Brian J; Lee, Daniel K C; Anhøj, Jacob

    2002-01-01

    AIMS: To study the effects of electrostatics in a plastic spacer on the lung deposition of salbutamol in asthmatic children. METHODS: Twenty-five children (5-12 years) with mild asthma were given salbutamol hydrofluoroalkane pressurized metered dose inhaler 400 micro g via a 750 ml plastic spacer...

  17. The CRISPR Spacer Space Is Dominated by Sequences from Species-Specific Mobilomes.

    Science.gov (United States)

    Shmakov, Sergey A; Sitnik, Vassilii; Makarova, Kira S; Wolf, Yuri I; Severinov, Konstantin V; Koonin, Eugene V

    2017-09-19

    Clustered regularly interspaced short palindromic repeats and CRISPR-associated protein (CRISPR-Cas) systems store the memory of past encounters with foreign DNA in unique spacers that are inserted between direct repeats in CRISPR arrays. For only a small fraction of the spacers, homologous sequences, called protospacers, are detectable in viral, plasmid, and microbial genomes. The rest of the spacers remain the CRISPR "dark matter." We performed a comprehensive analysis of the spacers from all CRISPR- cas loci identified in bacterial and archaeal genomes, and we found that, depending on the CRISPR-Cas subtype and the prokaryotic phylum, protospacers were detectable for 1% to about 19% of the spacers (~7% global average). Among the detected protospacers, the majority, typically 80 to 90%, originated from viral genomes, including proviruses, and among the rest, the most common source was genes that are integrated into microbial chromosomes but are involved in plasmid conjugation or replication. Thus, almost all spacers with identifiable protospacers target mobile genetic elements (MGE). The GC content, as well as dinucleotide and tetranucleotide compositions, of microbial genomes, their spacer complements, and the cognate viral genomes showed a nearly perfect correlation and were almost identical. Given the near absence of self-targeting spacers, these findings are most compatible with the possibility that the spacers, including the dark matter, are derived almost completely from the species-specific microbial mobilomes. IMPORTANCE The principal function of CRISPR-Cas systems is thought to be protection of bacteria and archaea against viruses and other parasitic genetic elements. The CRISPR defense function is mediated by sequences from parasitic elements, known as spacers, that are inserted into CRISPR arrays and then transcribed and employed as guides to identify and inactivate the cognate parasitic genomes. However, only a small fraction of the CRISPR spacers

  18. Pros and cons of symmetrical dual-k spacer technology in hybrid FinFETs

    Science.gov (United States)

    Pradhan, K. P.; Andrade, M. G. C.; Sahu, P. K.

    2016-12-01

    The symmetrical dual-k spacer technology in hybrid FinFETs has been widely explored for better electrostatic control of the fin-based devices in nanoscale region. Since, high-k tangible spacer materials are broadly became a matter of study due to their better immunity to the short channel effects (SCEs) in nano devices. However, the only cause that restricts the circuit designers from using high-k spacer is the unreasonable increasing fringing capacitances. This work quantitatively analyzed the benefits and drawbacks of considering two different dielectric spacer materials symmetrically in either sides of the channel for the hybrid device. From the demonstrated results, the inclusion of high-k spacer predicts an effective reduction in off-state leakage along with an improvement in drive current. However, these devices have paid the cost in terms of a high total gate-to-gate capacitance (Cgg) that consequently results poor cutoff frequency (fT) and delay.

  19. Partial nucleotide sequences, and routine typing by polymerase chain reaction-restriction fragment length polymorphism, of the brown trout (Salmo trutta) lactate dehydrogenase, LDH-C1*90 and *100 alleles.

    Science.gov (United States)

    McMeel, O M; Hoey, E M; Ferguson, A

    2001-01-01

    The cDNA nucleotide sequences of the lactate dehydrogenase alleles LDH-C1*90 and *100 of brown trout (Salmo trutta) were found to differ at position 308 where an A is present in the *100 allele but a G is present in the *90 allele. This base substitution results in an amino acid change from aspartic acid at position 82 in the LDH-C1 100 allozyme to a glycine in the 90 allozyme. Since aspartic acid has a net negative charge whilst glycine is uncharged, this is consistent with the electrophoretic observation that the LDH-C1 100 allozyme has a more anodal mobility relative to the LDH-C1 90 allozyme. Based on alignment of the cDNA sequence with the mouse genomic sequence, a local primer set was designed, incorporating the variable position, and was found to give very good amplification with brown trout genomic DNA. Sequencing of this fragment confirmed the difference in both homozygous and heterozygous individuals. Digestion of the polymerase chain reaction products with BslI, a restriction enzyme specific for the site difference, gave one, two and three fragments for the two homozygotes and the heterozygote, respectively, following electrophoretic separation. This provides a DNA-based means of routine screening of the highly informative LDH-C1* polymorphism in brown trout population genetic studies. Primer sets presented could be used to sequence cDNA of other LDH* genes of brown trout and other species.

  20. Competitor analogs for defined T cell antigens: peptides incorporating a putative binding motif and polyproline or polyglycine spacers.

    Science.gov (United States)

    Maryanski, J L; Verdini, A S; Weber, P C; Salemme, F R; Corradin, G

    1990-01-12

    We describe a new approach for modeling antigenic peptides recognized by T cells. Peptide A24 170-182 can compete with other antigenic peptides that are recognized by H-2kd-restricted cytolytic T cells, presumably by binding to the Kd molecule. By comparing substituted A24 peptides as competitors in a functional competition assay, the A24 residues Tyr-171, Thr-178, and Leu-179 were identified as possible contact residues for Kd. A highly active competitor peptide analog was synthesized in which Tyr was separated from the Thr-Leu pair by a pentaproline spacer. The choice of proline allowed the prediction of a probable conformation for the analog when bound to the Kd molecule. The simplest conformation of the A24 peptide that allows the same spacing and orientation of the motif as in the analog would be a nearly extended polypeptide chain incorporating a single 3(10) helical turn or similar structural kink.

  1. BWR fuel assembly with improved spacer and fuel bundle design for enhanced thermal-hydraulic performance

    International Nuclear Information System (INIS)

    Mildrum, C.M.; Taleyarkhan, R.P.

    1987-01-01

    In a fuel assembly having a bundle of elongated fuel rods disposed in side-by-side relationship so as to form an array of spaced fuel rods, an outer tubular flow channel surrounding the fuel rods so as to direct flow of coolant/moderator fluid along the fuel rods, a hollow water cross extending centrally through and interconnected with the outer flow channel so as to divide the channel into separate compartments and the bundle of fuelrods into a plurality of mini-bundles thereof being disposed in the compartments, and spacers axially displaced along the fuel rods in each of the mini-bundles thereof. Each spacer is composed of inner and outer means which together define spacer cells at corner, side and interior locations of the spacer and have respective protrusions formed thereon which extend into cells so as to maintain the fuel rods received through the spacer cells in laterally spaced relationships. The improvement is described which comprises: (a) a generally uniform poison coating within at least a majority of the fuel rods; (b) a predetermined pattern of fuel enrichment with respect to the fuel rods of each mini-bundle thereof which together with the uniform poison coating within the fuel rods ensures that the packing powers of the fuel rods in the corner and side cells of the spacers are less than the peaking power of a leading one of the fuel rods in the interior cells of the spacers; and (c) each of the fuel rods being received through the cells of each spacer having a diametric size smaller than that of each of the fuel rods received through the side and interior cells of each spacer, the diametric sizes of each of the fuel rods received through the side and interior cells of each spacer being generally equal

  2. Polyetheretherketone (PEEK) Spacers for Anterior Cervical Fusion: A Retrospective Comparative Effectiveness Clinical Trial.

    Science.gov (United States)

    Lemcke, Johannes; Al-Zain, Ferass; Meier, Ullrich; Suess, Olaf

    2011-01-01

    Anterior cervical decompression and fusion (ACDF) is the standard surgical treatment for radiculopathy and myelopathy. Polyetheretherketone (PEEK) has an elasticity similar to bone and thus appears well suited for use as the implant in ACDF procedures. The aim of this study is to examine the clinical and radiographic outcome of patients treated with standing alone PEEK spacers without bone morphogenic protein (BMP) or plating and to examine the influence of the different design of the two spacers on the rate of subsidence and dislocation. This retrospective comparative study reviewed 335 patients treated by ACDF in a specialized urban hospital for radiculopathy or myelopathy due to degenerative pathologies. The Intromed PEEK spacer was used in 181 patients from 3/2002 to 11/2004, and the AMT SHELL spacer was implanted in 154 patients from 4/2004 to 12/2007. The follow-up rate was 100% at three months post-op and 82.7% (277 patients) at one year. The patients were assessed with the Japanese Orthopedic Association (JOA) questionnaire and radiographically. At the one-year follow-up there were 118/277 patients with an excellent clinical outcome on the JOA, 112/277 with a good outcome, 20/277 with a fair outcome, and 27/277 with a poor outcome. Subsidence was observed in 13.3% of patients with the Intromed spacer vs 8.4% of the patients with the AMT SHELL. Dislocation of the spacer was observed in 10 of the 181 patients with Intromed spacers but in none of the 154 patients with Shell spacers. The study demonstrates that ACDF with standing alone PEEK cages leads to excellent and good clinical outcomes. The differences we observed in the subsidence rate between the two spacers were not significant and cannot be related to a single design feature of the spacers.

  3. Definition of Eight Mulberry Species in the Genus Morus by Internal Transcribed Spacer-Based Phylogeny.

    Directory of Open Access Journals (Sweden)

    Qiwei Zeng

    Full Text Available Mulberry, belonging to the order Rosales, family Moraceae, and genus Morus, has received attention because of both its economic and medicinal value, as well as for its important ecological function. The genus Morus has a worldwide distribution, however, its taxonomy remains complex and disputed. Many studies have attempted to classify Morus species, resulting in varied numbers of designated Morus spp. To address this issue, we used information from internal transcribed spacer (ITS genetic sequences to study the taxonomy of all the members of generally accepted genus Morus. We found that intraspecific 5.8S rRNA sequences were identical but that interspecific 5.8S sequences were diverse. M. alba and M. notabilis showed the shortest (215 bp and the longest (233 bp ITS1 sequence length, respectively. With the completion of the mulberry genome, we could identify single nucleotide polymorphisms within the ITS locus in the M. notabilis genome. From reconstruction of a phylogenetic tree based on the complete ITS data, we propose that the Morus genus should be classified into eight species, including M. alba, M. nigra, M. notabilis, M. serrata, M. celtidifolia, M. insignis, M. rubra, and M. mesozygia. Furthermore, the classification of the ITS sequences of known interspecific hybrid clones into both paternal and maternal clades indicated that ITS variation was sufficient to distinguish interspecific hybrids in the genus Morus.

  4. Definition of Eight Mulberry Species in the Genus Morus by Internal Transcribed Spacer-Based Phylogeny.

    Science.gov (United States)

    Zeng, Qiwei; Chen, Hongyu; Zhang, Chao; Han, Minjing; Li, Tian; Qi, Xiwu; Xiang, Zhonghuai; He, Ningjia

    2015-01-01

    Mulberry, belonging to the order Rosales, family Moraceae, and genus Morus, has received attention because of both its economic and medicinal value, as well as for its important ecological function. The genus Morus has a worldwide distribution, however, its taxonomy remains complex and disputed. Many studies have attempted to classify Morus species, resulting in varied numbers of designated Morus spp. To address this issue, we used information from internal transcribed spacer (ITS) genetic sequences to study the taxonomy of all the members of generally accepted genus Morus. We found that intraspecific 5.8S rRNA sequences were identical but that interspecific 5.8S sequences were diverse. M. alba and M. notabilis showed the shortest (215 bp) and the longest (233 bp) ITS1 sequence length, respectively. With the completion of the mulberry genome, we could identify single nucleotide polymorphisms within the ITS locus in the M. notabilis genome. From reconstruction of a phylogenetic tree based on the complete ITS data, we propose that the Morus genus should be classified into eight species, including M. alba, M. nigra, M. notabilis, M. serrata, M. celtidifolia, M. insignis, M. rubra, and M. mesozygia. Furthermore, the classification of the ITS sequences of known interspecific hybrid clones into both paternal and maternal clades indicated that ITS variation was sufficient to distinguish interspecific hybrids in the genus Morus.

  5. Definition of Eight Mulberry Species in the Genus Morus by Internal Transcribed Spacer-Based Phylogeny

    Science.gov (United States)

    Zeng, Qiwei; Chen, Hongyu; Zhang, Chao; Han, Minjing; Li, Tian; Qi, Xiwu; Xiang, Zhonghuai; He, Ningjia

    2015-01-01

    Mulberry, belonging to the order Rosales, family Moraceae, and genus Morus, has received attention because of both its economic and medicinal value, as well as for its important ecological function. The genus Morus has a worldwide distribution, however, its taxonomy remains complex and disputed. Many studies have attempted to classify Morus species, resulting in varied numbers of designated Morus spp. To address this issue, we used information from internal transcribed spacer (ITS) genetic sequences to study the taxonomy of all the members of generally accepted genus Morus. We found that intraspecific 5.8S rRNA sequences were identical but that interspecific 5.8S sequences were diverse. M. alba and M. notabilis showed the shortest (215 bp) and the longest (233 bp) ITS1 sequence length, respectively. With the completion of the mulberry genome, we could identify single nucleotide polymorphisms within the ITS locus in the M. notabilis genome. From reconstruction of a phylogenetic tree based on the complete ITS data, we propose that the Morus genus should be classified into eight species, including M. alba, M. nigra, M. notabilis, M. serrata, M. celtidifolia, M. insignis, M. rubra, and M. mesozygia. Furthermore, the classification of the ITS sequences of known interspecific hybrid clones into both paternal and maternal clades indicated that ITS variation was sufficient to distinguish interspecific hybrids in the genus Morus. PMID:26266951

  6. Predicting the impact of feed spacer modification on biofouling by hydraulic characterization and biofouling studies in membrane fouling simulators

    KAUST Repository

    Siddiqui, Amber; Lehmann, S.; Bucs, Szilard; Fresquet, M.; Fel, L.; Prest, E.I.E.C.; Ogier, J.; Schellenberg, C.; van Loosdrecht, M.C.M.; Kruithof, J.C.; Vrouwenvelder, Johannes S.

    2016-01-01

    Feed spacers are an essential part of spiral-wound reverse osmosis (RO) and nanofiltration (NF) membrane modules. Geometric modification of feed spacers is a potential option to reduce the impact of biofouling on the performance of membrane systems

  7. In vitro performance of three combinations of spacers and pressurized metered dose inhalers for treatment in children

    DEFF Research Database (Denmark)

    Berg, E; Madsen, J; Bisgaard, H

    1998-01-01

    The performance of pressurized metered dose inhalers (pMDIs) and spacers in correct dose recommendations is important, but limited information on dose delivery and fine-particle dose from different combinations of spacers and pMDIs is available. In this study, three combinations of spacers and p...... and spacers, with the NebuChamber giving the highest dose, both as delivered dose and in droplets account for these differences....

  8. Soft antimicrobial agents: synthesis and activity of labile environmentally friendly long chain quaternary ammonium compounds.

    Science.gov (United States)

    Thorsteinsson, Thorsteinn; Másson, Már; Kristinsson, Karl G; Hjálmarsdóttir, Martha A; Hilmarsson, Hilmar; Loftsson, Thorsteinn

    2003-09-11

    A series of soft quaternary ammonium antimicrobial agents, which are analogues to currently used quaternary ammonium preservatives such as cetyl pyridinium chloride and benzalkonium chloride, were synthesized. These soft analogues consist of long alkyl chain connected to a polar headgroup via chemically labile spacer group. They are characterized by facile nonenzymatic and enzymatic degradation to form their original nontoxic building blocks. However, their chemical stability has to be adequate in order for them to have antimicrobial effects. Stability studies and antibacterial and antiviral activity measurements revealed relationship between activity, lipophilicity, and stability. Their minimum inhibitory concentration (MIC) was as low as 1 microg/mL, and their viral reduction was in some cases greater than 6.7 log. The structure-activity studies demonstrate that the bioactive compounds (i.e., MIC for Gram-positive bacteria of <10 microg/mL) have an alkyl chain length between 12 and 18 carbon atoms, with a polar headgroup preferably of a small quaternary ammonium group, and their acquired inactivation half-life must be greater than 3 h at 60 degrees C.

  9. Evaluation of spacer grid spring characteristics by means of physical tests and numerical simulation

    Energy Technology Data Exchange (ETDEWEB)

    Schettino, Carlos Frederico Mattos, E-mail: carlosschettino@inb.gov.br [Industrias Nucleares do Brasil (INB), Resende, RJ (Brazil)

    2017-11-01

    Among all fuel assemblies' components, the spacer grids play an important structural role during the energy generation process, mainly due for its primary functional requirement, that is, to provide fuel rod support. The present work aims to evaluate the spring characteristics of a specific spacer grid design used in a PWR fuel assembly type 16 x 16. These spring characteristics comprises the load versus deflection capability and its spring rate, which are very important, and also mandatory, to be correctly established in order to preclude spacer grid spring and fuel rod cladding fretting during operation, as well as prevent an excessive fuel rod buckling. This study includes physical tests and numerical simulation. The tests were performed on an adapted load cell mechanical device, using as a specimen a single strap of the spacer grid. Three numerical models were prepared using the Finite Element Method, with the support of the commercial code ANSYS. One model was built to validate the simulation according to the performed physical test, the others were built inserting a gradient of temperature (Beginning Of Life hot condition) and to evaluate the spacer grid spring characteristics in End Of Life condition. The obtained results from physical test and numerical model have shown a good agreement between them, therefore validating the simulation. The obtained results from numerical models make available information regarding the spacer grid design purpose, such as the behavior of the fuel rod cladding support during operation. Therewith, these evaluations could be useful to improve the spacer grid design. (author)

  10. System for measuring spacer pin pitch in a nuclear fuel assembly

    International Nuclear Information System (INIS)

    Isono, Kenji; Tateishi, Yoshinori; Mano, Tadashi.

    1975-01-01

    Object: To reduce the period for discriminating whether or not spacer pin pitch is satisfactory by simultaneously inserting a number of reference rods into a nuclear fuel assembly spacer ring element of a reactor and arranging them such that they can be simultaneously withdrawn to simplify the withdrawing operation. Structure: A spacer provided with a ring element which clamps a nuclear fuel element is supported on a spacer support with a rod secured to the support as a guide and is secured to the support by securing means. A vertically movable structure with a reference rod provided upright and thru-holes formed in two support plates provided in the same row as the spacer ring element is operated by a fluid pressure mechanism to simultaneously insert the reference rod into the spacer ring element. The reference rod is mounted in support plates via ball bearings such that it is slightly movable in the horizontal direction, and it is aligned with respect to the core of the ring element. The intercore distance of the reference rod is measured with the reference rod inserted in the ring element, thereby measuring the space pin pitch. From the results of measurement, discrimination as to whether the spacer is satisfactory or not is made. (Kamimura, M.)

  11. A Study on Cell Size of Irradiated Spacer Grid for PWR Fuel

    International Nuclear Information System (INIS)

    Jin, Y. G.; Kim, G. S.; Ryu, W. S. and others

    2014-01-01

    The spacer grids supporting the fuel rods absorb vibration impacts due to the reactor coolant flow, and grid spring force decreases under irradiation. This reduction of contact force might cause grid-to-rod fretting wear. The fretting failure of the fuel rod is one of the recent significant issues in the nuclear industry from an economical as well as a safety concern. Thus, it is important to understand the characteristics of cell spring behavior and the change in size of grid cells for an irradiated spacer grid. In the present study, the dimensional measurement of a spacer grid was conducted to investigate the cell size of an irradiated spacer grid in a hot cell at IMEF (Irradiated Materials Examination Facility) of KAERI. To evaluate the fretting wear performance of an irradiated spacer grid, hot cell tests were carried out at IMEF of KAERI. Hot cell examinations include dimensional measurements for the irradiated spacer grid. The change of cell sizes was dependent on the direction of the spacer grids, leading to significant gap variations. It was found that the change in size of the cell springs due to irradiation-induced stress relaxation and creep during the fuel residency in the reactor core affect the contact behavior between the fuel rod and the cell spring

  12. Antibiotic-impregnated articulating cement spacer for infected total knee arthroplasty

    Directory of Open Access Journals (Sweden)

    Parag Garg

    2011-01-01

    Full Text Available Background : Standard treatment of chronic infected total knee arthroplasty (TKA is a two-stage revision, the first step being placement of an antibiotic-impregnated cement spacer. Here we describe the results of a new technique (modification of the Goldstien′s technique for intraoperative manufacture of a customized articulating spacer at minimal cost and with relatively good conformity and longevity. Materials and Methods : Thirty-six infected knees underwent this procedure from June 2002 to May 2007. The technique consists of using the freshened femur and tibia interface as molds wrapped in a tin foil for manufacturing the two components of the spacer with antibiotic-impregnated methyl methycrylate cement. We used the spacer and the femoral component of the trial set of a TKA system to mold them to perfect articulation. We also reinforced the spacer with a K-wire scaffold to prevent fracture of the cement mantle in the last 21 cases. Results : All 36 knees showed excellent results in terms of infection control, mobility, and stability. There was significant improvement in the WOMAC and Knee Society Scores (20 and 39 points respectively. There were two fractures of the spacers in the initial 15 cases that did not have K-wire scaffolding but none in the last 21 that had reinforcement. Conclusion : This technique provides a more conforming spacer, with good range of motion and stability. The reinforcement helps in preventing the fracture of the cement mantle and is cost effective.

  13. Experimental investigation of turbulent flow through spacer grids in fuel rod bundles

    International Nuclear Information System (INIS)

    Caraghiaur, Diana; Anglart, Henryk; Frid, Wiktor

    2009-01-01

    This paper contains experimental data of pressure, velocity and turbulence intensity in a 24-rod fuel bundle with spacer grids. Detailed pressure measurements inside the spacer grid have been obtained by use of a sliding pressure-sensing rod. Laser Doppler Velocimetry technique was used to measure the local axial velocity and its fluctuating component upstream and downstream of the spacer grid in sub-channels with different blockage ratios. The measurements show a changing pattern in function of radial position in the cross-section of the fuel bundle. For sub-channels close to the box wall, the turbulence intensity suddenly increases just downstream of the spacer and then gradually decays. In inner sub-channels, however, the turbulence intensity downstream of the spacer decreases below its upstream value and then gradually increases until it reaches the maximum value at approximately two spacer heights. The present study reveals that spacer effects, such as local pressure distribution and turbulence intensity enhancement, not only depend exclusively on the local geometry details, but also on the location in the cross-section of the rod bundle.

  14. Experimental investigation of turbulent flow through spacer grids in fuel rod bundles

    Energy Technology Data Exchange (ETDEWEB)

    Caraghiaur, Diana [Royal Institute of Technology, Division of Nuclear Reactor Technology, Department of Physics, School of Engineering Sciences, AlbaNova University Center, SE-106 91 Stockholm (Sweden)], E-mail: dianac@kth.se; Anglart, Henryk [Royal Institute of Technology, Division of Nuclear Reactor Technology, Department of Physics, School of Engineering Sciences, AlbaNova University Center, SE-106 91 Stockholm (Sweden); Frid, Wiktor [Swedish Radiation Safety Authority, Reactor Technology and Structural Integrity, SE-171 16 Stockholm (Sweden)

    2009-10-15

    This paper contains experimental data of pressure, velocity and turbulence intensity in a 24-rod fuel bundle with spacer grids. Detailed pressure measurements inside the spacer grid have been obtained by use of a sliding pressure-sensing rod. Laser Doppler Velocimetry technique was used to measure the local axial velocity and its fluctuating component upstream and downstream of the spacer grid in sub-channels with different blockage ratios. The measurements show a changing pattern in function of radial position in the cross-section of the fuel bundle. For sub-channels close to the box wall, the turbulence intensity suddenly increases just downstream of the spacer and then gradually decays. In inner sub-channels, however, the turbulence intensity downstream of the spacer decreases below its upstream value and then gradually increases until it reaches the maximum value at approximately two spacer heights. The present study reveals that spacer effects, such as local pressure distribution and turbulence intensity enhancement, not only depend exclusively on the local geometry details, but also on the location in the cross-section of the rod bundle.

  15. Evaluation of spacer grid spring characteristics by means of physical tests and numerical simulation

    International Nuclear Information System (INIS)

    Schettino, Carlos Frederico Mattos

    2017-01-01

    Among all fuel assemblies' components, the spacer grids play an important structural role during the energy generation process, mainly due for its primary functional requirement, that is, to provide fuel rod support. The present work aims to evaluate the spring characteristics of a specific spacer grid design used in a PWR fuel assembly type 16 x 16. These spring characteristics comprises the load versus deflection capability and its spring rate, which are very important, and also mandatory, to be correctly established in order to preclude spacer grid spring and fuel rod cladding fretting during operation, as well as prevent an excessive fuel rod buckling. This study includes physical tests and numerical simulation. The tests were performed on an adapted load cell mechanical device, using as a specimen a single strap of the spacer grid. Three numerical models were prepared using the Finite Element Method, with the support of the commercial code ANSYS. One model was built to validate the simulation according to the performed physical test, the others were built inserting a gradient of temperature (Beginning Of Life hot condition) and to evaluate the spacer grid spring characteristics in End Of Life condition. The obtained results from physical test and numerical model have shown a good agreement between them, therefore validating the simulation. The obtained results from numerical models make available information regarding the spacer grid design purpose, such as the behavior of the fuel rod cladding support during operation. Therewith, these evaluations could be useful to improve the spacer grid design. (author)

  16. Experimental determination of temperature fields in sodium-cooled rod bundles with hexagonal rod arrangement and grid spacers

    International Nuclear Information System (INIS)

    Moeller, R.; Tschoeke, H.; Kolodziej, M.

    1977-01-01

    Three-dimensional temperature fields in the claddings of sodium cooled rods were determined experimentally under representative nominal operating conditions for a SNR typical 19-rod bundle model provided with spark-eroded spacers. These experiments are required to verify thermohydraulic computer programs which will provide the output data for strength calculations of the high loaded cladding tubes. In this work the essentials are reported of the measured circumferential distributions of wall temperatures of peripheral rods. In addition the sub-channel temperatures measured over the bundle cross section are indicated, they are required to sustain codes for the global thermohydraulic design of core elements. The most important results are: 1) The whole fuel element is located within the thermal entrance length. 2) High azimuthal temperature differences were measured in the claddings of peripheral rods, which are strongly influenced by the distance between the rod and the shroud, especially for the corner rod. 3) With decreasing Pe-number ( [de

  17. Success of Two-Stage Reimplantation in Patients Requiring an Interim Spacer Exchange.

    Science.gov (United States)

    George, Jaiben; Miller, Evan M; Curtis, Gannon L; Klika, Alison K; Barsoum, Wael K; Mont, Michael A; Higuera, Carlos A

    2018-03-23

    Some patients undergoing a 2-stage revision for a periprosthetic joint infection require a repeat spacer in the interim (removal of existing spacer with insertion of a new spacer or spacer exchange) due to persistent infection. The objectives of this study are to (1) determine the factors associated with patients who receive a repeat spacer and (2) compare the infection-free survival (overall and stratified by joint type) of reimplantation in patients who did or did not receive a repeat spacer. From 2001 to 2014, 347 hip or knee 2-stage revisions that finally underwent reimplantation and had a minimum 2-year follow-up were identified. An interim spacer exchange was performed in 59 (17%) patients (exchange cohort). Patient-related and organism-related factors were compared between the exchange and non-exchange cohorts. Kaplan-Meier survival curves were performed to assess the success (absence of signs of infection, reoperation for infection, periprosthetic joint infection-related mortality) of both cohorts. Patients in the exchange group had higher comorbidity score (P = .020), prolonged time to reimplantation (P exchange cohort, and 78% (knee 77%, hip 78%) in the non-exchange cohort (P = .020). Patients requiring an interim spacer exchange were found to have more comorbidities, prolonged treatment period, and were more likely to be infected with a resistant organism. About one-third of such patients became reinfected within 5 years compared to only one-fifth of the patients without an interim spacer exchange. Copyright © 2018 Elsevier Inc. All rights reserved.

  18. Characterization of feed channel spacer performance using geometries obtained by X-ray computed tomography

    KAUST Repository

    Haaksman, Viktor A.

    2016-09-09

    Spiral-wound membrane modules used in water treatment for water reuse and desalination make use of spacer meshes for keeping the membrane leaves apart and for enhancing the mass transfer. Computational fluid dynamics (CFD) has gained importance in the design of new spacers with optimized hydrodynamic characteristics, but this requires a precise description of the spacer geometry. This study developed a method to obtain accurate three-dimensional (3-D) geometry representations for any given spacer design from X-ray computed tomography (CT) scans. The method revealed that the filaments of industrial spacers have a highly variable cross-section size and shape, which impact the flow characteristics in the feed channel. The pressure drop and friction factors were calculated from numerical simulations on five commercially available feed spacers used in practice. Model solutions compared well to experimental data measured using a flow cell for average velocities up to 0.2 m/s, as used in industrial reverse osmosis and nanofiltration membrane operations. A newly-proposed spacer geometry with alternating strand thickness was tested, which was found to yield a lower pressure drop while being highly efficient in converting the pumping power into membrane shear. Numerical model solutions using CFD with geometries from CT scans were closer to measurements than those obtained using the traditional circular cross-section strand simplification, indicating that CT scans are very well suitable to approximate real feed spacer geometries. By providing detailed insight on the spacer filament shape, CT scans allow better quantification of local distribution of velocity and shear, possibly leading to more accurate estimations of fouling and concentration polarization. © 2016 Elsevier B.V.

  19. Efficient self-assembly of DNA-functionalized fluorophores and gold nanoparticles with DNA functionalized silicon surfaces: the effect of oligomer spacers

    Science.gov (United States)

    Milton, James A.; Patole, Samson; Yin, Huabing; Xiao, Qiang; Brown, Tom; Melvin, Tracy

    2013-01-01

    Although strategies for the immobilization of DNA oligonucleotides onto surfaces for bioanalytical and top-down bio-inspired nanobiofabrication approaches are well developed, the effect of introducing spacer molecules between the surface and the DNA oligonucleotide for the hybridization of nanoparticle–DNA conjugates has not been previously assessed in a quantitative manner. The hybridization efficiency of DNA oligonucleotides end-labelled with gold nanoparticles (1.4 or 10 nm diameter) with DNA sequences conjugated to silicon surfaces via hexaethylene glycol phosphate diester oligomer spacers (0, 1, 2, 6 oligomers) was found to be independent of spacer length. To quantify both the density of DNA strands attached to the surfaces and hybridization with the surface-attached DNA, new methodologies have been developed. Firstly, a simple approach based on fluorescence has been developed for determination of the immobilization density of DNA oligonucleotides. Secondly, an approach using mass spectrometry has been created to establish (i) the mean number of DNA oligonucleotides attached to the gold nanoparticles and (ii) the hybridization density of nanoparticle–oligonucleotide conjugates with the silicon surface–attached complementary sequence. These methods and results will be useful for application with nanosensors, the self-assembly of nanoelectronic devices and the attachment of nanoparticles to biomolecules for single-molecule biophysical studies. PMID:23361467

  20. Quantifying Short-Chain Chlorinated Paraffin Congener Groups

    NARCIS (Netherlands)

    Yuan, Bo; Bogdal, Christian; Berger, Urs; MacLeod, Matthew; Gebbink, Wouter A.; Alsberg, Tomas; Wit, de Cynthia A.

    2017-01-01

    Accurate quantification of short-chain chlorinated paraffins (SCCPs) poses an exceptional challenge to analytical chemists. SCCPs are complex mixtures of chlorinated alkanes with variable chain length and chlorination level; congeners with a fixed chain length (n) and number of chlorines (m) are

  1. An experimental investigation of supercritical heat transfer in a three-rod bundle equipped with wire-wrap and grid spacers and cooled by carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Eter, Ahmad, E-mail: eng.eter@yahoo.com; Groeneveld, Dé, E-mail: degroeneveld@gmail.com; Tavoularis, Stavros, E-mail: stavros.tavoularis@uottawa.ca

    2016-07-15

    Highlights: • Heat transfer at supercritical pressures was studied experimentally in a three-rod bundle equipped with wire-wrap spacers or grid spacers. • Heat transfer deterioration occurred near the heated inlet under certain conditions. • Normal heat transfer was generally comparable to that in a tube and the predictions of a correlation. - Abstract: Heat transfer measurements in a three-rod bundle equipped with wire-wrap and grid spacers were obtained at supercritical pressures in the Supercritical University of Ottawa Loop (SCUOL). The tests were performed using carbon dioxide, as a surrogate fluid for water, flowing upwards for wide ranges of conditions, including conditions equivalent to the nominal and near-normal operating conditions of the proposed Canadian Super-Critical Water-Cooled Reactor. The test section contained three heated rods and three unheated rod segments with an outer diameter of 10 mm and a pitch-to-diameter ratio of 1.14; the heated length was 1500 mm. Detailed surface temperature measurements along and around the three heated rods were collected using internally traversed thermocouples. The following ranges of test conditions were covered, with equivalent water conditions given inside parentheses: pressure from 6.6 to 8.36 MPa (19.7–25 MPa); inlet temperature from 11 to 30 °C (330–371 °C); mass flux from 200 to 1175 kg m{sup −2} s{sup −1} (340–1822 kg m{sup −2} s{sup −1}); and wall heat flux from 1 to 175 kW m{sup −2} (11–1847 kW m{sup −2}). For one set of tests, the heated rods were fitted with a 1.3 mm OD wire wrap, having an axial pitch of 200 mm along the entire heated length; for a second set, the heated rods were fitted with grid spacers having a 5.3% flow blockage and located at 500 mm axial intervals. The effects of spacer configuration on heat transfer at supercritical pressures were documented and analyzed. The observed experimental trends were compared to those obtained in a experiment in a heated

  2. APPLICATIONS OF SPACERS MADE WITH DOUBLE BAR RASCHEL MACHINE

    Directory of Open Access Journals (Sweden)

    DÍAZ-GARCÍA Pablo

    2016-05-01

    Full Text Available Nowadays, textile technologies develop to adapt their different techniques for creating new products for the different sectors of application every day. Particularly, warp knitted fabrics and warp-knitting technology have applications in all different groups of technical textiles. It could be the most applied technique, the most versatile technology to develop new textile products for the new textile market. Warp knitted fabrics play the most important role among the technical textile fabrics. This technology is used in different product groups such as mobile textiles (car seat covers, dashboard cover, industrial textiles (composites, medical textiles (anti-decubitus blankets, sports textiles and foundation garments (bra cups, pads for swimwear. This study presents some examples of the application of this technology in some markets Within the market of technical textile, medical textile has an increasing relevance and knitted fabrics and knitting technology, at the same time, play a very important role in the fields of technical and medical textiles. Studies have demonstrated that knitted structures possess excellent mechanical properties and can promote more effective regenerative medicine, tissue repair, ligament, tendon cartilage, reconstruction, etc. The aim of this paper is to present different possibilities of textiles developed with this kind of structures, to present different alternatives, different examples of products obtained with this kind of textile structure combined with the correct kind of textile fiber. In this kind of technology, double-bar Raschel machines used for producing three-dimensional textiles, spacers, play an important role.

  3. Chain Assembly and Disassembly Processes Differently Affect the Conformational Space of Ubiquitin Chains.

    Science.gov (United States)

    Kniss, Andreas; Schuetz, Denise; Kazemi, Sina; Pluska, Lukas; Spindler, Philipp E; Rogov, Vladimir V; Husnjak, Koraljka; Dikic, Ivan; Güntert, Peter; Sommer, Thomas; Prisner, Thomas F; Dötsch, Volker

    2018-02-06

    Ubiquitination is the most versatile posttranslational modification. The information is encoded by linkage type as well as chain length, which are translated by ubiquitin binding domains into specific signaling events. Chain topology determines the conformational space of a ubiquitin chain and adds an additional regulatory layer to this ubiquitin code. In particular, processes that modify chain length will be affected by chain conformations as they require access to the elongation or cleavage sites. We investigated conformational distributions in the context of chain elongation and disassembly using pulsed electron-electron double resonance spectroscopy in combination with molecular modeling. Analysis of the conformational space of diubiquitin revealed conformational selection or remodeling as mechanisms for chain recognition during elongation or hydrolysis, respectively. Chain elongation to tetraubiquitin increases the sampled conformational space, suggesting that a high intrinsic flexibility of K48-linked chains may contribute to efficient proteasomal degradation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Tunnel current across linear homocatenated germanium chains

    International Nuclear Information System (INIS)

    Matsuura, Yukihito

    2014-01-01

    The electronic transport properties of germanium oligomers catenating into linear chains (linear Ge chains) have been theoretically studied using first principle methods. The conduction mechanism of a Ge chain sandwiched between gold electrodes was analyzed based on the density of states and the eigenstates of the molecule in a two-probe environment. Like that of silicon chains (Si chains), the highest occupied molecular orbital of Ge chains contains the extended σ-conjugation of Ge 4p orbitals at energy levels close to the Fermi level; this is in contrast to the electronic properties of linear carbon chains. Furthermore, the conductance of a Ge chain is expected to decrease exponentially with molecular length L. The decay constant β, which is defined as e −βL , of a Ge chain is similar to that of a Si chain, whereas the conductance of the Ge chains is higher than that of Si chains even though the Ge–Ge bond length is longer than the Si–Si bond length

  5. Photoorientation phenomena and structural properties of photochromic liquid crystalline azobenzene-containing polymethacrylate films with different spacer lengths

    Czech Academy of Sciences Publication Activity Database

    Bobrovsky, A.; Shibaev, V.; Piryazev, A.; Anokhin, D.V.; Ivanov, D.A.; Sinitsyna, O.; Hamplová, Věra; Kašpar, Miroslav; Bubnov, Alexej M.

    2017-01-01

    Roč. 218, č. 16 (2017), s. 1-10, č. článku 1700127. ISSN 1022-1352 R&D Projects: GA ČR GA16-12150S; GA MŠk(CZ) LH15305 Institutional support: RVO:68378271 Keywords : photoorientation phenomena * azobenzene * photo-optical properties * liquid crystal * photochromic materials Subject RIV: JJ - Other Materials OBOR OECD: Nano-materials (production and properties) Impact factor: 2.500, year: 2016

  6. Identification of Candida species by PCR and restriction fragment length polymorphism analysis of intergenic spacer regions of ribosomal DNA.

    OpenAIRE

    Williams, D W; Wilson, M J; Lewis, M A; Potts, A J

    1995-01-01

    The PCR was used to amplify a targeted region of the ribosomal DNA from 84 Candida isolates. Unique product sizes were obtained for Candida guilliermondii, Candida (Torulopsis) glabrata, and Candida pseudotropicalis. Isolates of Candida albicans, Candida tropicalis, Candida stellatoidea, Candida parapsilosis, and Candida krusei could be identified following restriction digestion of the PCR products.

  7. Extreme conservation of the psaA/psaB intercistronic spacer reveals a translational motif coincident with the evolution of land plants.

    Science.gov (United States)

    Peredo, Elena L; Les, Donald H; King, Ursula M; Benoit, Lori K

    2012-12-01

    Although chloroplast transcriptional and translational mechanisms were derived originally from prokaryote endosymbionts, chloroplasts retain comparatively few genes as a consequence of the overall transfer to the nucleus of functions associated formerly with prokaryotic genomes. Various modifications reflect other evolutionary shifts toward eukaryotic regulation such as posttranscriptional transcript cleavage with individually processed cistrons in operons and gene expression regulated by nuclear-encoded sigma factors. We report a notable exception for the psaA-psaB-rps14 operon of land plant (embryophyte) chloroplasts, where the first two cistrons are separated by a spacer region to which no significant role had been attributed. We infer an important function of this region, as indicated by the conservation of identical, structurally significant sequences across embryophytes and their ancestral protist lineages, which diverged some 0.5 billion years ago. The psaA/psaB spacers of embryophytes and their progenitors exhibit few sequence and length variants, with most modeled transcripts resolving the same secondary structure: a loop with projecting Shine-Dalgarno site and well-defined stem that interacts with adjacent coding regions to sequester the psaB start codon. Although many functions of the original endosymbiont have been usurped by nuclear genes or interactions, conserved functional elements of embryophyte psaA/psaB spacers provide compelling evidence that translation of psaB is regulated here by a cis-acting mechanism comparable to those common in prokaryotes. Modeled transcripts also indicate that spacer variants in some plants (e.g., aquatic genus Najas) potentially reflect ecological adaptations to facilitate temperature-regulated translation of psaB.

  8. Articulating spacers used in two-stage revision of infected hip and knee prostheses abrade with time.

    Science.gov (United States)

    Fink, Bernd; Rechtenbach, Annett; Büchner, Hubert; Vogt, Sebastian; Hahn, Michael

    2011-04-01

    Articulating spacers used in two-stage revision surgery of infected prostheses have the potential to abrade and subsequently induce third-body wear of the new prosthesis. We asked whether particulate material abraded from spacers could be detected in the synovial membrane 6 weeks after implantation when the spacers were removed for the second stage of the revision. Sixteen hip spacers (cemented prosthesis stem articulating with a cement cup) and four knee spacers (customized mobile cement spacers) were explanted 6 weeks after implantation and the synovial membranes were removed at the same time. The membranes were examined by xray fluorescence spectroscopy, xray diffraction for the presence of abraded particles originating from the spacer material, and analyzed in a semiquantitative manner by inductively coupled plasma mass spectrometry. Histologic analyses also were performed. We found zirconium dioxide in substantial amounts in all samples, and in the specimens of the hip synovial lining, we detected particles that originated from the metal heads of the spacers. Histologically, zirconium oxide particles were seen in the synovial membrane of every spacer and bone cement particles in one knee and two hip spacers. The observations suggest cement spacers do abrade within 6 weeks. Given the presence of abrasion debris, we recommend total synovectomy and extensive lavage during the second-stage reimplantation surgery to minimize the number of abraded particles and any retained bacteria.

  9. Effects of grid spacer with mixing vane on entrainments and depositions in two-phase annular flows

    Directory of Open Access Journals (Sweden)

    Akimaro Kawahara

    2015-06-01

    Full Text Available The effects of mixing vanes (MVs attached to a grid spacer on the characteristics of air–water annular flows were experimentally investigated. To know the effects, a grid spacer with or without MV was inserted in a vertical circular pipe of 16-mm internal diameter. For three cases (i.e., no spacer, spacer without MV, and spacer with MV, the liquid film thickness, liquid entrainment fraction, and deposition rate were measured by the constant current method, single liquid film extraction method, and double liquid film extraction method, respectively. The MVs significantly promote the re-deposition of liquid droplets in the gas core flow into the liquid film on the channel walls. The deposition mass transfer coefficient is three times higher for the spacer with MV than for the spacer without MV, even for cases 0.3-m downstream from the spacer. The liquid film thickness becomes thicker upstream and downstream for the spacer with MV, compared with the thickness for the spacer without MV and for the case with no spacer.

  10. A simulation methodology of spacer grid residual spring deflection for predictive and interpretative purposes

    International Nuclear Information System (INIS)

    Kim, K. T.; Kim, H. K.; Yoon, K. H.

    1994-01-01

    The in-reactor fuel rod support conditions against the fretting wear-induced damage can be evaluated by spacer grid residual spring deflection. In order to predict the spacer grid residual spring deflection as a function of burnup for various spring designs, a simulation methodology of spacer grid residual spring deflection has been developed and implemented in the GRIDFORCE program. The simulation methodology takes into account cladding creep rate, initial spring deflection, initial spring force, and spring force relaxation rate as the key parameters affecting the residual spring deflection. The simulation methodology developed in this study can be utilized as an effective tool in evaluating the capability of a newly designed spacer grid spring to prevent the fretting wear-induced damage

  11. The independent loss model with ordered insertions for the evolution of CRISPR spacers.

    Science.gov (United States)

    Baumdicker, F; Huebner, A M I; Pfaffelhuber, P

    2018-02-01

    Today, the CRISPR (clustered regularly interspaced short palindromic repeats) region within bacterial and archaeal genomes is known to encode an adaptive immune system. We rely on previous results on the evolution of the CRISPR arrays, which led to the ordered independent loss model, introduced by Kupczok and Bollback (2013). When focusing on the spacers (between the repeats), new elements enter a CRISPR array at rate θ at the leader end of the array, while all spacers present are lost at rate ρ along the phylogeny relating the sample. Within this model, we compute the distribution of distances of spacers which are present in all arrays in a sample of size n. We use these results to estimate the loss rate ρ from spacer array data for n=2 and n=3. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. The effect of endoskeleton on antibiotic impregnated cement spacer for treating deep hip infection

    Directory of Open Access Journals (Sweden)

    Hsu Wei-Hsiu

    2011-01-01

    Full Text Available Abstract Backgrounds A two-stage revision arthroplasty was suggested optimal treatment for deep infections in hip joint. The effect of endoskeleton of cement spacers on the interim function and infection control remains unclear. Methods From Jan. 2004 to Dec. 2007, we collected a prospective cohort of consecutive 34 patients who treated with two-stage revision total hip arthroplasty for deep infection of hip joint. In group 1, fifteen patients were treated by a novel design augmented with hip compression screw while nineteen patients were treated by traditional design in group 2. Results No fracture of cement spacer occurred in group 1 while 6 cases developed spacer failure in group 2. (p Conclusions Patients being treated for deep infection of hip joint using cement spacer augmented with stronger endoskeleton have lower pain levels and better joint function between stages.

  13. Biofouling patterns in spacer filled channels: High resolution imaging for characterization of heterogeneous biofilms

    KAUST Repository

    Staal, Marc; Siddiqui, Amber; van Loosdrecht, Mark; Vrouwenvelder, Johannes S.

    2017-01-01

    reverse osmosis (RO) and nanofiltration (NF) membrane filtration systems used for desalination and wastewater reuse to produce high quality (drinking) water. Thes