bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative assessment of alkyl chain branching in alcohol‐based surfactants by nuclear magnetic resonance
Authors: van Duynhoven J. P. M. , Leika A. , van der Hoeven P. C.
Published: November 2006

Surfactants with branched hydrophobes have gained considerable interest, since these can be used in formulations for laundry cleaning at a wide range of conditions. The claims range from improved dissolution rate to hardness tolerance and stain removing efficacy. In contrast to the historically known heavily branched surfactants, novel branched surfactants are less compromised by increased biodegradability. These properties find their basis in the structural characteristics of the hydrophobe, such as number, position, and type of alkyl chain branches. Our current understanding of structure‐property relations, however, is hampered by the lack of generic methodology needed to obtain structural data on hydrophobe branching. A nuclear magnetic resonance (NMR) approach was developed by which we could obtain a comprehensive set of quantitative hydrophobe branching parameters in alcoholbased surfactants. The13C and1H NMR spin systems of hydrophobe branched species were assigned by means of twodimensional NMR techniques. These assignments allowed the quantitative assessment of these branched species by straight‐forward signal integration in the1H and13C NMR spectra. The quantified NMR data can be used to understand product performance and the biodegradation of surfactants with branched hydrophobes.
The role of surface tension on the residual water content of fabrics
Authors: Carter D. L. , Shah D. O.
Published: November 2006

Cotton has been shown to hold up to 80% of its initial weight in water due to strong capillary forces after washing. According to the LaPlace equation for capillary rise, the rise is proportional to the surface tension of the air‐liquid interface. The use of a tailored rinse additive has the potential to alter the surface tension of solutions significantly, thus leading to a lower capillary rise. This lower rise can be related to the residual water content in fabrics. The reduction of surface tension lowers the force required to displace liquid inside the capillaries formed by fabric fibers. If the amount of residual water in fabrics can be significantly lowered, the drying time of the fabrics would be decreased as well. We have shown that by reducing the surface tension of solutions, the residual moisture content of fabrics also decreases.
Effect of cefoperazone sodium on the physicochemical properties of surfactants
Authors: Qian Junhong , Gu Jinghua , Xia Jiding
Published: November 2006

The effects of cefoperazone sodium (CS), a pharmaceutical compound, on the critical micelle concentration (CMC) of surfactants with different charges [cetyl trimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and Triton X‐100], the cloud point of Triton X‐100, and the Krafft temperatures of SDS and CTAB were studied. The interaction of CS with differently charged surfactants was determined by ultraviolet and fluorescence spectrophotometry. The results show that with increasing CS concentration, the Krafft temperature increases and the CMC decreases in the SDS/H2O system, whereas the opposite results are obtained in the CTAB/H2O system. Both the cloud point and the CMC of Triton X‐100 increase with the addition of CS. The above results are attributed to the different micellar interactions between CS and surfactants with different charges.
Partition of bromophenol blue in toluene/water/sodium bis(2‐ethylhexyl)‐sulfosuccinate water‐in‐oil microemulsions
Authors: Sarma Surashree , Dutta Robin K.
Published: November 2006

The partition of bromophenol blue between oil‐water interfaces and water droplets in water‐in‐oil microemulsions of toluene/water/sodium bis(2‐ethylhexyl)sulfosuccinate was studied by a spectroscopic method at different water fractions and pH. The partition equilibrium constant, Kp, between the two domains decreased considerably with an increase in the water fraction and pH. The decrease in Kp with an increase in the water fraction suggests the retention of more dye molecules in water. The decrease in Kp with an increase in pH has been attributed to a lower tendency of the base form to associate with the anionic oil‐water interface compared with that of the acid form and to an increase in the negative charge density at the oil‐water interface at a higher pH.
Change in the aggregational character of the cationic surfactant cetyl trimethyl ammonium bromide in the presence of o‐ and p‐itrophenolates
Authors: Gokhale G. D. , Hassan P. A. , Samant S. D.
Published: November 2006

The effect of the addition of sodium salts of p‐nitrophenol and o‐nitrophenol on the structural transition of aqueous micellar solutions of the cationic surfactant cetyl trimethyl ammonium bromide (CTAB) was studied by viscosity, 1H nuclear magnetic resonance, and dynamic light scattering measurements. The rapid increase in the relative viscosity of CTAB solutions on the addition of sodium salts of o‐nitrophenol and p‐nitrophenol was due to the transition in micellar shape from spheres to rods. Dynamic light scattering studies indicated a decrease in the diffusion coefficient of the micelles with the addition of p‐nitrophenol. The adsorption and orientation of the salts on the micellar surface and subsequent growth of the micelles was studied by nuclear magnetic resonance.
N‐halosuccinimide‐mercaptoethanol cohalogenation of olefinic fatty methyl esters: Synthesis of β‐halo thioethoxylates
Authors: Singh Sukhprit , Singh Bhupinderpal
Published: November 2006

Olefinic fatty methyl esters, undec‐10‐enoate (1), octadec‐Z‐9‐enoate (2), methyl‐12 hydroxy octadec‐Z‐9‐enoate (3), on reaction with N‐halosuccinimides (4,5), that is, N‐bromosuccinimide (4) or N‐chlorosuccinimide (5) and 2‐mercaptoethanol (6) in benzene, gave β‐bromo‐ or β‐chlorothioethoxylates (8–13). β‐Halothioethoxylates so formed were acetylated with acetyl chloride in CH2Cl2 to form the respective acetylated products (20–25).
Mixed micelles of cationic surfactants and bile acid salts in aqueous media
Authors: George Alex , Vora Sambhav , Dogra Arti , Desai Hemangi , Bahadur Pratap
Published: November 2006

Critical micelle concentrations of cetyltrimethylammonium‐p‐toluene sulfonate (CTAT) and cetylpyridinium chloride (CPC) with sodium cholate (NaC) and sodium deoxycholate (NaDC) were determined in aqueous solutions by surface tension measurements. Interaction parameters and mole fraction of the components in mixed micelles were estimated using Rubingh's theory. Strong interaction was observed for each mixed system, a common feature shown by anionic‐cationic mixtures. Dramatic effects on the viscosities of these cationic surfactant‐bile salt mixtures were seen, and were markedly dependent upon the counterion of the cationic surfactant and the nature of bile salts. Micelles are small and spherical for cationic surfactants in the presence of NaC. Micelle growth was seen for CPC in the presence of NaDC by an increase in viscosity, but a CTAT solution showed an opposite effect on addition of NaDC. Conductance results supported this view. Different behavior of the two bile salts is explained on the basis of their orientation in cationic micelles.
Surface and thermodynamic studies of N‐alkkyl N‐trimethylsilane ammonium chloride surfactants
Authors: Gad E. A. M. , Badawi A. M. , Zaki M.
Published: November 2006

N‐Dodecyl N‐trimethylsilane ammonium chloride, N‐tetradecyl‐N‐trimethylsilane ammonium chloride, N‐hexadecyl‐N‐trimethylsilane ammonium chloride, and N‐octadecyl‐N‐trimethylsilane ammonium chloride were prepared. Surface properties, particularly critical micelle concentration (CMC), effectiveness, maximum surface excess, and minimal surface area, were determined at different concentrations at 20, 35, 50, and 65°C, respectively. From electrical conductivity data, degrees of dissociation and dissociation constants at various concentrations were determined. Free energies, enthalpies, and entropies of micellization and adsorption of the surfactants in aqueous solution were studied.
Modified data handling for rapid low‐field nuclear magnetic resonance characterization of lyotropic liquid crystal composites
Authors: Nadakatti Suresh M.
Published: November 2006

A refined nuclear magnetic resonance (NMR) technique was developed to determine the relative volumetric proportions of various phases present in lyotropic liquid crystal (LLC) composites such as soap/detergent bars. Conventionally, the FID (free induction decay, referred to hereafter as Method 1) technique is used for analysis of these systems. This technique is suitable only for composites containing a high concentration of solids and liquid crystals. Method 1 gives erroneous results for composites with a high proportion (>10%) of isotropic liquid phase (L1). The procedure currently practiced (Method 2) for analyzing systems containing >10% L1 entails a considerable amount of experimental and analysis time and involves subjectivity in data analysis. Typically, the phase characterization of the composite using conventional low‐field NMR techniques takes more than 1 h. Furthermore, the hardware and data acquisition features of currently available conventional low‐field NMR spectrometers are inadequate for accurate estimation of relative phase volumes in LLC composites. We developed a modified data‐handling technique (FID—Carr‐Purcell‐Meiboom‐Gill technique, or FIDCPMG technique) which enabled rapid phase characterization of LLC composites and minimized subjectivity while analyzing the data. The standard design of a conventional low‐field NMR spectrometer was upgraded by incorporating a high‐power transmitter and a fast digitizer. The phase composition of four model LLC composites (with L1 percentages varying from 7 to 90%) was determined using FIDCPMG technique and was compared with results from conventional techniques. Phase composition of the LLC composite could be determined in less than 5 min.
Overexpression of acyl‐CoA binding protein and its effects on the flux of free fatty acids in McA‐RH 7777 cells
Authors: Yang Yingying , Pritchard P. Haydn , Bhuiyan Jalal , Seccombe David W. , Moghadasian Mohammed H.
Published: November 2006

Overexpression of acyl‐CoA binding protein (ACBP) was induced in a rat hepatoma cell line (McA‐RH 7777) by stable integration of rat ACBP cDNA. The transfected cells (ACBP‐27) had 3.5‐fold higher concentrations of ACBP than control cells (14 vs. 4 ng/μg DNA). Both ACBP‐27 and control cells were cultured in the presence of various concentrations of radiolabeled palmitic acid; and the effects of ACBP on lipogenesis and β‐oxidation were studied. Incubation of the cells with 100 μM palmitic acid resulted in 42% greater incorporation of the fatty acid in ACBP‐27 cells as compared to that in the control cells. This increased incorporation of the fatty acid was observed predominanly in the triglyceride fraction. Higher concentrations of palmitic acid (200 to 400 μM) were associated with a significant decrease in the production of 14CO2 in the ACBP‐27 cell line than in the control cells, while lower concentrations had not effect. Our data suggest a role for ACBP in the partitioning of fatty acids between esterification reactions leading to the formation of neutral lipids and β‐oxidation. ACBP may play a regulatory role by influencing this important branch point in intermediary lipid metabolism.
Synthesis of a novel series of 2‐methylsulfanyl fatty acids and their toxicity on the human K‐562 and U‐937 leukemia cell lines
Authors: Carballeira Néstor M. , Miranda Carlos , Orellano Elsie A. , González Fernando A.
Published: November 2006

The hitherto unknown 2‐methylsulfanyldecanoic acid and 2‐methylsulfanyldodecanoic acid were synthesized from methyl decanoate and methyl dodecanoate, respectively, through the reaction of lithium diisopropylamide and dimethyldisulfide in THF followed by saponification with potassium hydroxide in ethanol. Both α‐methylsulfanylated FA were cytotoxic to the human chronic myelogenous leukemia K‐562 and the human histiocytic lymphoma U‐937 cell lines with EC50 values in the 200–300 μM range, which makes them more cytotoxic to these cell lines than decanoic and/or dodecanoic acid. The cytotoxicity of the studied FA toward K‐562 followed the order 2‐SCH3‐12∶0>2‐SCH3‐10∶0>10∶0>12∶0>2‐OCH3‐12∶0, whereas toward U‐937 the cytotoxicity was 2‐SCH3‐10∶0>2‐SCH3‐12∶0>12∶0>10∶0>2‐OCH3‐12∶0. These results indicate that the α‐methylsulfanyl substitution increases the cytotoxicity of the C10 and C12 FA toward the studied leukemia cell lines.
Synthesis of dihydroperoxides of linoleic and linolenic acids and studies on their transformation to 4‐hydroperoxynonenal
Authors: Schneider Claus , Boeglin William E. , Yin Huiyong , Stec Donald F. , Hachey David L. , Porter Ned A. , Brash Alan R.
Published: November 2006

The cytotoxic aldehydes 4‐hydroxynonenal, 4‐hydroperoxynonenal (4‐HPNE), and 4‐oxononenal are formed during lipid peroxidation via oxidative transformation of the hydroxy or hydroperoxy precursor fatty acids, respectively. The mechanism of the carbon chain cleavage reaction leading to the aldehyde fragments is not known, but Hock‐cleavage of a suitable dihydroperoxide derivative was implicated to account for the fragmentation [Schneider, C., Tallman, K.A., Porter, N.A., and Brash, A.R. (2001) Two Distinct Pathways of Formation of 4‐Hydroxynonenal. Mechanisms of Nonenzymatic Transformation of the 9‐ and 13‐Hydroperoxides of Linoleic Acid to 4‐Hydroxyalkenals, J. Biol. Chem. 275, 20831–20838]. Both 8,13‐ and 10,13‐dihydroperoxyoctadecadienoic acids (diHPODE) could serve as precursors in a Hock‐cleavage leading to 4‐HPNE via two different pathways. Here, we synthesized diastereomeric 9,12‐, 10,12‐, and 10,13‐diHPODE using singlet oxidation of linoleic acid. 8,13‐Dihydroperoxyoctadecatrienoic acid was synthesized by vitamin E‐controlled autoxidation of γ‐linolenic acid followed by reaction with soybean lipoxygenase. The transformation of these potential precursors to 4‐HPNE was studied under conditions of autoxidation, hematin‐, and acid‐catalysis. In contrast to 9‐ or 13‐HPODE, neither of the dihydroperoxides formed 4‐HPNE on autoxidation (lipid film, 37°C), regardless of whether the free acid or the methyl ester derivative was used. Acid treatment of 10,13‐diHPODE led to the expected formation of 4‐HPNE as a significant product, in accord with a Hock‐type cleavage reaction. We conclude that, although the suppression of 4‐H(P)NE formation from monohydroperoxides by α‐tocopherol indicates peroxyl radical reactions in the major route of carbon chain cleavage, the dihydroperoxides previously implicated are not intermediates in the autoxidative transformation of monohydroperoxy fatty acids to 4‐HPNE and related aldehydes.
Analogs of squalene and oxidosqualene inhibit oxidosqualene cyclase of Trypanosoma cruzi expressed in Saccharomyces cerevisiae
Authors: Oliaro‐Bosso Simonetta , Ceruti Maurizio , Balliano Gianni , Milla Paola , Rocco Flavio , Viola Franca
Published: November 2006

Recently, a number of inhibitors of the enzyme oxidosqualene cyclase (OSC; EC 5.4.99.7), a key enzyme in sterol biosynthesis, were shown to inhibit in mammalian cells the multiplication of Trypanosoma cruzi, the parasite agent of Chagas’ disease. The gene coding for the OSC of T. cruzi has been cloned and expressed in Saccharomyces cerevisiae. The expression in yeast cells could be a safe and easy model for studying the activity and the selectivity of the potential inhibitors of T. cruzi OSC. Using a homogenate of S. cerevisiae cells expressing T. cruzi OSC, we have tested 19 inhibitors: aza, methylidene, vinyl sulfide, and conjugated vinyl sulfide derivatives of oxidosqualene and squalene, selected as representative of different classes of substrate analog inhibitors of OSC. The IC50 values of inhibition (the compound concentration at which the enzyme is inhibited by 50%) are compared with the values obtained using OSC of pig liver and S. cerevisiae. Many inhibitors of pig liver and S. cerevisiae OSC show comparable IC50 for T. cruzi OSC, but some phenylthiovinyl derivatives are 10–100 times more effective on the T. cruzi enzyme than on the pig or S. cerevisiae enzymes. The expression of proteins of pathogenic organisms in yeast seems very promising for preliminary screening of compounds that have potential therapeutic activity.
Fatty acid and hydroxy acid adaptation in three gram‐negative hydrocarbon‐degrading bacteria in relation to carbon source
Authors: Soltani Mohamed , Metzger Pierre , Largeau Claude
Published: November 2006

The lipids of three gram‐negative bacteria, Acineto‐bacter calcoaceticus, Marinobacter aquaeolei, and Pseudomonas oleovorans grown on mineral media supplemented with ammonium acetate or hydrocarbons, were isolated, purified, and their structures determined. Three pools of lipids were isolated according to a sequential procedure: unbound lipids extracted with organic solvents, comprising metabolic lipids and the main part of membrane lipids, OH−‐labile lipids (mainly ester‐bound in the lipopolysaccharides, LPS) and H+‐labile lipids (mainly amidebound in the LPS). Unsaturated FA composition gave evidence for an aerobic desaturation pathway for the synthesis of these acids in A. calcoaceticus and M. aquaeolei, a nonclassic route in gram‐negative bacteria. Surprisingly, both aerobic and anaerobic pathways are operating in the studied strain of P. oleovorans. The increase of the proportion of saturated FA observed for the strain of P. oleovorans grown on light hydrocarbons would increase the temperature transition of the lipids for maintaining the inner membrane fluidity. An opposite phenomenon occurs in A. calcoaceticus and M. aquaeolei grown on solid or highly viscous C19 hydrocarbons. The increases of FA<C18 when the bacteria were grown on n‐nonadecane, or of iso‐FA in cultures on iso‐nonadecane would decrease the transition temperature of the lipids, to maintain the fluidity of the inner membranes. Moreover, P. oleovorans grown on hydrocarbons greatly decreases the proportion of β‐hydroxy acids of LPS, thus likely maintaining the physical properties of the outer membrane. By contrast, no dramatic change in hydroxy acid composition occurred in the other two bacteria.
Lhca5 interaction with plant photosystem I
Authors: Lucinski Robert , Schmid Volkmar H.R. , Jansson Stefan , Klimmek Frank
Published: November 2006

In the outer antenna (LHCI) of higher plant photosystem I (PSI) four abundantly expressed light‐harvesting protein of photosystem I (Lhca)‐type proteins are organized in two heterodimeric domains (Lhca1/Lhca4 and Lhca2/Lhca3). Our cross‐linking studies on PSI‐LHCI preparations from wildtype Arabidopsis and pea plants indicate an exclusive interaction of the rarely expressed Lhca5 light‐harvesting protein with LHCI in the Lhca2/Lhca3‐site. In PSI particles with an altered LHCI composition Lhca5 assembles in the Lhca1/Lhca4 site, partly as a homodimer. This flexibility indicates a binding‐competitive model for the LHCI assembly in plants regulated by molecular interactions of the Lhca proteins with the PSI core.
Casein kinase 1 delta (CK1δ) interacts with the SNARE associated protein snapin
Authors: Wolff Sonja , Stöter Martin , Giamas Georgios , Piesche Matthias , Henne-Bruns Doris , Banting George , Knippschild Uwe
Published: November 2006

In this study we identified snapin as an interaction partner of the CK1 isoform delta (CK1δ) in the yeast two‐hybrid system and localized the interacting domains of both proteins. The interaction of CK1δ with snapin was confirmed by co‐immunoprecipitation. Snapin was phosphorylated by CK1δ in vitro. Both proteins localized in close proximity in the perinuclear region, wherein snapin was found to associate with membranes of the Golgi apparatus. The identification of snapin as a new substrate of CK1δ points towards a possible function for CK1δ in modulating snapin specific functions.
Berry & Kohn's Operating Room Technique
Authors: Holcomb Christine Brown
Published: November 2006

BERRY & KOHN'S OPERATING ROOM TECHNIQUE, eighth Ed By Lucy Jo Atkinson, Nancymarie Fortunato 1996, 988 pp $47.95 hardcover
Reengineering of Operative and Invasive Services
Authors: Shaner‐Christy Patricia A.
Published: November 2006

REENGINEERING OF OPERATIVE AND INVASIVE SERVICES, By Mae Taylor Moss 1997, 189 pp $79 spiralbound
The dynamics of strong turbulence at free surfaces. Part 1. Description
Authors: BROCCHINI M. , PEREGRINE D. H.
Published: November 2006

A free surface may be deformed by fluid motions; such deformation may lead to
surface roughness, breakup, or disintegration. This paper describes the wide range
of free-surface deformations that occur when there is turbulence at the surface,
and focuses on turbulence in the denser, liquid, medium. This turbulence may be
generated at the surface as in breaking water waves, or may reach the surface
from other sources such as bed boundary layers or submerged jets. The discussion
is structured by consideration of the stabilizing influences of gravity and surface
tension against the disrupting effect of the turbulent kinetic energy. This leads to
a two-parameter description of the surface behaviour which gives a framework for
further experimental and theoretical studies. Much of the discussion is necessarily
heuristic, and is often limited by a lack of appropriate experimental observations. It
is intended that such experiments be stimulated, to test the value or otherwise of our
two-parameter description.
Accurate refraction–diffraction equations for water waves on a variable-depth rough bottom
Authors: AGNON YEHUDA , PELINOVSKY EFIM
Published: November 2006

The extended mild-slope equation and the modified mild-slope equation have been
used successfully to study refraction–diffraction of linear water waves by steep bottom
roughness. Their consistency has been questioned. A systematic derivation of these
model equations exposes and illuminates their rationale. Their good performance
stems from an accurate representation of (Class I) Bragg resonance. As a benchmark
test case, we consider scattering by a sloping bottom with random roughness. The
rates of scattering found for the mean field in both of the approximate models agree
exactly with the full theory for scattering by small roughness. This greatly improves
the limited agreement which was found for the mild-slope equation, and establishes
the validity of the above model equations. The study involves operator calculus, a
powerful method for simplifying problems with variable coefficients. The augmented
mild-slope equation serves to consistently derive accurate model equations.
On local boundary-layer receptivity to vortical disturbances in the free stream
Authors: WU XUESONG
Published: November 2006

Prompted by the recent experiments of Dietz (1999) on boundary-layer receptivity
due to a local roughness interacting with a vortical disturbance in the free stream, this
paper undertakes to present a second-order asymptotic theory based on the
tripledeck formulation. The asymptotic approach allows us to treat vortical perturbations
with a fairly general vertical distribution, and confirms Dietz's conclusion that for
the convecting periodic wake in his experiments, the receptivity is independent of
its vertical structure and can be fully characterized by its slip velocity at the edge
of the boundary layer. As in the case of distributed vortical receptivity, dominant
interactions that generate Tollmien–Schlichting waves take place in the upper deck as
well as in the so-called edge layer centred at the outer reach of the boundary layer. The
initial amplitude of the excited Tollmien–Schlichting wave is determined to O(R−1/8) accuracy,
where R is the global Reynolds number. An appropriate superposition
formula is derived for the case of multiple roughness elements. A comprehensive
comparison is made with Dietz's experimental data, and an excellent quantitative
agreement has been found for the first time, thereby resolving some uncertainties
about this receptivity mechanism.
Flow-Erleben unter kontrollierter Beanspruchungssteuerung
Authors: Reinhardt Christian , Lau Andreas , Hottenrott Kuno , Stoll Oliver
Published: November 2006

Zusammenfassung. Sportliche Aktivitäten wurden von Anbeginn in die Flow-Forschung einbezogen, wobei recht bald deutlich wurde, dass eine verlaufsnahe Diagnostik, also einer Diagnostik während der sportlichen Tätigkeit, dem Flow-Konstrukt am Besten entspricht. Allerdings liefern Feldstudien, welche die Auslösebedingungen für das Auftreten von Flow und die Flow-Leistungsbeziehung bei sportlichen Aktivitäten zu klären versuchen, eher inkonsistente Befunde. Ziel der vorliegenden Laufbandstudie war es daher: 1) zu prüfen, ob die von Csikszentmihalyi (1975) postulierte Anforderungs-Fähigkeits-Passung für Läufer auch unter Laborbedingungen Voraussetzung für das Auftreten von Flow ist und 2) die Dynamik des Flow-Erlebens im Zeitverlauf und in Abhängigkeit physiologischer Leistungsparameter beim Laufen zu dokumentieren. Mit Hilfe einer beanspruchungsorientierten Geschwindigkeitssteuerung des Laufbands gelang es, die Probanden (N = 30) auf einem individuell bestimmten, überdurchschnittlichem Anspruchsniveau kontrolliert 40 Minuten laufen zu lassen. Im Fazit lässt sich feststellen, dass die Probanden über ein tiefes und im Verlauf stabiles Flow-Erleben berichten. Allerdings ist dies davon unabhängig, ob sie subjektiv eine optimale Anforderungs-Fähigkeits-Passung erleben.
Determinants of Pro-Environmental Behaviors
Authors: Lévy-Leboyer Claude , Bonnes Mirilia , Chase John , Ferreira-Marques Jose , Pawlik Kurt
Published: November 2006

Research teams in five countries (France, Germany, Italy, Portugal, UK) developed in common a comparative study on individual attitudes and behaviors towards the environment, and on the importance of environmental issues in the media of these countries. The sample was composed of 742 subjects, teachers and engineers. Results presented here focus on a cross-countries comparison of the media analysis and the questionnaire data. Important differences are observed between the level of pro-environmental behaviors and the nature of their determinants.
High frequency measurements of HFCs at a remote site in east Asia and their implications for Chinese emissions
Authors: Yokouchi Y. , Taguchi S. , Saito T. , Tohjima Y. , Tanimoto H. , Mukai H.
Published: November 2006

High frequency monitoring of hydrofluorocarbons (HFCs) and some other halocarbons in the atmosphere has been performed at Hateruma Island (lat. 24.1°N, long. 123.8°E), a background site in east Asia. The observed concentrations showed occasional short‐term enhancement events over hours to days as well as a clear seasonal variation, being lower in summer than in other seasons. We found that HFC‐23 enhancements were closely related to the air transport from China. Using a tagged simulation from three‐dimensional transport model and a tracer‐ratio technique, the emission rate of HFC‐23 from China was estimated to amount to 10 Gg (= 10 000 metric tonnes) per year with an uncertainty of 50%, which could account for two thirds of the total global emission. HFCs emitted from Japan, Korea, and Taiwan were characterized by a predominance of HFC‐134a with very little contribution of HFC‐23.
Airborne measurements of carbonaceous aerosol soluble in water over northeastern United States: Method development and an investigation into water‐soluble organic carbon sources
Authors: Sullivan A. P. , Peltier R. E. , Brock C. A. , de Gouw J. A. , Holloway J. S. , Warneke C. , Wollny A. G. , Weber R. J.
Published: November 2006

A particle‐into‐liquid sampler (PILS) was coupled to a total organic carbon (TOC) analyzer for 3 s integrated measurements of water‐soluble organic carbon (WSOC) in PM1 ambient particles. The components of the instrument are described in detail. The PILS‐TOC was deployed on the NOAA WP‐3D aircraft during the NEAQS/ITCT 2004 program to investigate WSOC sources over the northeastern United States and Canada. Two main sources were identified: biomass burning emissions from fires in Alaska and northwestern Canada and emissions emanating from urban centers. Biomass burning WSOC was correlated with carbon monoxide (CO) and acetonitrile (r2 > 0.88). These plumes were intercepted in layers at altitudes between 3 and 4 km and contained the highest fine particle volume and WSOC concentrations of the mission. Apart from the biomass burning influence, the lowest WSOC concentrations were recorded in rural air masses that included regions of significant biogenic emissions. Highest concentrations were at low altitudes in distinct plumes from urban centers. WSOC and CO were highly correlated (r2 > 0.78) in these urban plumes. The ratio of the enhancement in WSOC relative to CO enhancement was found to be low (∼3 μg C/m3/ppmv) in plumes that had been in transit for a short time, and increased with plume age, but appeared to level off at ∼32 ± 4 μg C/m3/ppmv after ∼1 day of transport from the sources. The results suggest that the production of WSOC in fine particles depends on compounds coemitted with CO and that this process is rapid with a time constant of ∼1 day.
Upgraded two-dimensional phase contrast imaging system for fluctuation profile measurement on LHD
Authors: Michael C. A. , Tanaka K. , Vyacheslavov L. , Sanin A. , Kawahata K. , Okajima S.
Published: November 2006

The two-dimensional (2D) phase contrast imaging system on LHD can measure the k spectrum of line-integrated density fluctuations (k∼0.2–3mm−1 and k⊥ρi∼0.1–1.5) with modest spatial resolution (Δρ∼0.1) along a line of sight passing close to the magnetic axis, sensitive to radial fluctuations in the core and poloidal fluctuations in the edge. The spatial resolution is attained using a 6×8 2D detector array taking advantage of the strong magnetic shear in LHD. The system can be configured with different magnification factors to investigate different ranges of k (in “overview” mode from 0.2to0.6mm−1, characteristic of ITG/TEM scale turbulence; and “zoom” mode from 1to3mm−1, which may access to the lower limit of the ETG range). Zoom mode additionally employs cylindrical optics to stretch the image by a factor of 4 in order to provide better spatial resolution for high k fluctuations within a narrow spatial region. The highest detected value of k in zoom mode, for which the signal-to-noise ratio is better than 1, is 2.5mm−1 (at around 1.5MHz).
Correlated hydrogen bonding fluctuations and vibrational cross peaks in N-methyl acetamide: Simulation based on a complete electrostatic density functional theory map
Authors: Hayashi Tomoyuki , Mukamel Shaul
Published: November 2006

The coherent nonlinear response of the entire amide line shapes of N-methyl acetamide to three infrared pulses is simulated using an electrostatic density functional theory map. Positive and negative cross peaks contain signatures of correlations between the fundamentals and the combination state. The amide I-A and I-III cross-peak line shapes indicate positive correlation and anticorrelation of frequency fluctuations, respectively. These can be ascribed to correlated hydrogen bonding at CO and N–H sites. The amide I frequency is negatively correlated with the hydrogen bond on carbonyl CO, whereas the amide A and III are negatively and positively correlated, respectively, with the hydrogen bond on amide N–H.
Micron and submicron patterning of polydimethylsiloxane resists on electronic materials by decal transfer lithography and reactive ion-beam etching: Application to the fabrication of high-mobility, thin-film transistors
Authors: Ahn Heejoon , Lee Keon Jae , Childs William R. , Rogers John A. , Nuzzo Ralph G. , Shim Anne
Published: November 2006

We describe a technique for fabricating micron and submicron-sized polydimethylsiloxane (PDMS) patterns on electronic material substrates using decal transfer lithography (DTL) in conjunction with reactive ion-beam etching (RIE). We validate the use of this unconventional polymeric system as a suitable resist material for fabricating Si-based microelectronic devices. In this process, an O2∕CF4 gas mixture was used to etch a supporting PDMS thin film that resides atop a closed-form decal polymer to reveal conventional resist structures. These structures provide an effective latent image that, in turn, provides for an extension of soft lithography as a form of multilayer lithography—one yielding submicron structures similar to those obtained from the conventional photochemical methods used to prepare such resists. This combined DTL/RIE patterning procedure was found to be compatible with commercially available planarization layers and provides a direct means for preparing high aspect ratio resist features. We illustrate the applicability of soft lithography as a means for fabricating electronic devices by using it to prepare model silicon-based thin-film transistors exploiting silicon-on-insulator wafer technology.
Spectroellipsometric studies of sol-gel derived Sr0.6Ba0.4Nb2O6 films
Authors: Ho Melanie M. T. , Tang T. B. , Mak C. L. , Pang G. K. H. , Chan K. Y. , Wong K. H.
Published: November 2006

Sr 0.6 Ba 0.4 Nb 2 O 6 (SBN) films have been fabricated on (001)Si substrates by a sol-gel technique. The annealing process was carried out in air at various temperatures ranging from 200to700°C. Studies using x-ray diffractometry, high resolution transmission electron microscopy, and scanning electron microscopy showed that polycrystalline films, with a grain size of about 100nm, were obtained only for annealing temperatures ⩾600°C. The optical properties of these sol-gel derived SBN films were studied by spectroscopic ellipsometry (SE). In the analysis of the measured SE spectra, a triple-layer Lorentz model has been developed and used to deduce the optical properties of the SBN films. Our systematic SE measurements revealed that the refractive indices of the SBN films increase with the annealing temperature. This increase is more pronounced at around the crystallization temperature, i.e., between 500 and 600°C. The extinction coefficients of the films also exhibit a similar trend, showing a zero value for amorphous films and larger values for films annealed at above 600°C. Our results demonstrate that while crystallization helps to raise the refractive index of the film due to film densification, it also promotes scattering by grain boundary, resulting in a larger extinction coefficient.
Sensitive slab optical waveguides composed of mesoporous metal-oxide thin films on the tin-diffused layers of float glass substrates
Authors: Qi Zhi-Mei , Wei Mingdeng , Honma Itaru , Zhou Haoshen
Published: November 2006

The application of uniform transparent mesoporous thin films for waveguide-based optical chemical and biological sensors could result in ultrahigh sensitivity due to a great increase in the depth of interaction between evanescent wave and analyte molecules adsorbed within the mesoporous film. For this purpose, we designed a low-loss, prism-coupling-compatible slab optical waveguide that can be prepared by deposition of sol-gel surfactant templated mesoporous metal-oxide thin films on the tin-diffused glass layers being intrinsic to float glass slides. In this study, mesoporous WO3 and SnO2 thin films were fabricated and the resulting elements were demonstrated to keep the waveguiding capability and to allow for in situ detection of molecular adsorption within the mesoporous film by single-beam polarimetric interferometry. Induced changes in the phase difference between the fundamental transverse electric and magnetic modes were detected by two methods: (a) monitoring of an interference fringe on the waveguide surface and (b) detection of the light emitting from the prism coupler.
Evidence of the 3π∕4 interaction mode in a compact magnetically insulated line oscillator process
Authors: Cousin Richard , Larour Jean , Gouard Philippe , Raymond Pierre
Published: November 2006

The electron beam generated in crossed-field devices such as the magnetron and the magnetically insulated line oscillator (MILO), which is closely related to the linear magnetron, interacts with a slow wave structure (SWS) in a configuration where the rf electromagnetic field is 180° out of phase from one cell to the next inside the periodic structure (the so-called π mode). We present here an analysis of a compact MILO device based on the U.S. Air Force geometry, where all dimensions are reduced by a factor of 2. By considering the geometrical parameters of the SWS, we establish precise criteria to maximize the microwave output power up to 3GW and to optimize the electronic efficiency up to 32%. To do so, the dispersion diagram is studied in such a way as to force the 3π∕4 mode in which the compact MILO oscillates. We report a discussion on the electromagnetic coupling in order to conclude on the output power stability of this interaction regime.
Preparation, characterization, and impedance studies of LiSbM(PO4)3 (M=Al, Fe, and Cr)
Authors: Rambabu G. , Anantharamulu N. , Vithal M. , Raghavender M. , Prasad G.
Published: November 2006

Lithium containing sodium superionic conductors of composition LiSbM(PO4)3 (M=Al, Cr, and Fe) were prepared by solid-state method and were characterized by powder x-ray diffraction and infrared spectroscopy. All compounds were found to crystallize in rhombohedral lattice with space group R3¯c. They show characteristic PO4 vibrational bands. The dc conductivity and ac impedance studies of all these samples correlate well in terms of activation energy of conduction Ea. The Cole-Cole plots do not show any spikes on the lower frequency side, indicating negligible electrode effects. The activation energies obtained from the plots of logσdc vs 1∕T and logσ(0) vs 1∕T are approximately the same suggesting conducting species to be mobile lithium ions. The peak width at half maximum for modulus plots (logf vs M″) is ∼1.34 decades for LiSbM(PO4)3 (M=Al, Cr, and Fe), which is close to 1.14 decades observed for a Debye solid. The heights of M″ obtained from the experimental plots are close to that of M″(max)=C0∕2C, confirming the Debye nature of these samples.
Molecular dynamics simulations of lubricant spreading on lubricant-patterned substrates
Authors: Li Xin , Hu Yuanzhong , Ma Tianbao , Wang Hui , Zhang Jun
Published: November 2006

The spreading of nonfunctional perfluoropolyether (PFPE) on PFPE-patterned substrates is examined using molecular dynamics simulations. During the spreading process, mobile molecules will encounter, pass by, and embrace the bonded ones. The movement of mobile molecules is hindered by the bonded ones. The spreading exhibits a slow evolution with time, a steep profile with a precursor film from a side view and a complicated profile from a top-down view. The atomic-scale mechanism is analyzed by the driving term, such as the van der Waals interaction and surface diffusion, and the resistance term, such as the interaction between bonded and mobile molecules or, furthermore, the combined interaction from the adjacent bonded molecules. Besides, the spreading profiles of PFPE on PFPE-patterned substrates with different coverage ratios are compared, which indicate that the coverage ratio has significant effects on the PFPE spreading behavior.
Fatigue properties of piezoelectric-electrostrictive Pb(Mg1∕3,Nb2∕3)O3–PbTiO3 monolithic bilayer composites
Authors: Hall A. , Akdogan E. K. , Safari A.
Published: November 2006

The fatigue response of monolithic piezoelectric 0.65Pb(Mg1∕3Nb2∕3)O3–0.35PbTiO3-electrostrictive 0.90Pb(Mg1∕3Nb2∕3)O3–0.10PbTiO3 bilayer composites was investigated experimentally. The monomorph bilayers were cosintered at 1150°C, and the polarization hysteresis, relative permittivity, displacement, and cyclic fatigue (107cycles) were measured as a function of piezoelectric-electrostrictive volume fraction (PEVF) ratio. The highest tip displacement of bilayers was found in the 3:1 PEVF monolith, reaching 40μm at 5kV∕cm applied field strength. By minimizing the electrostrictive layer thickness, tip displacement substantially increased, while maintaining a lower hysteresis than the purely piezoelectric counterpart. Fatigue measurements indicated a 31% decrease in displacement after 107cycles in 3:1 monoliths, whereas the 1:3 PEVF only showed a 12% decrease under the same conditions. There is a 30% increase in polarization after 107cycles for 1:1 PEVF bilayers, which is attributed to self-poling due to a diffuse transition layer in the vicinity of the interface. It was found that partial 90° domain switching occurred prior to poling because of the residual stresses in the composite, imposed by the electrostrictive layer and the spontaneous strain associated with the cubic-tetragonal transition in the ferroelectric layer. The results indicate that the electrostrictive layer, which is electrically in series with the piezoelectric one, enhances the fatigue resistance of the monolithic bilayer composites in addition to the increase in tip displacement.
Ti–Sn alloy nanodot composites embedded in single-crystal SiO2 by low energy dynamic coimplantation
Authors: Zhao J. P. , Meng Y. , Huang D. X. , Rayabarapu R. K. , Rabalais J. W.
Published: November 2006

Organized extremely small Ti–Sn alloy nanodots have been formed in the subsurface of SiO2 by dynamic coimplantation of isotopic Ti+48 and Sn+120 at a low kinetic energy of 9keV into (0001) Z-cut quartz at different substrate temperatures. Transmission electron microscopy images show that the Ti–Sn alloy nanodots are single crystal and have been formed uniformly at room temperature. They are distributed in a two-dimensional array with similar size of ∼4nm and constant interdot spacing between each dot. The regions beyond and below the two-dimensional array are depleted of detectable nanodots. At high temperature, the distribution and crystallinity were destroyed with much smaller amorphous nanodots in a slightly deeper region. The implantation was carried out by dynamic coimplantation, rather than the commonly used sequential implantation. These results indicate that dynamic low energy coimplantation is capable of forming well-ordered two-dimensional array of alloy nanodots.
Response to “Comment on ‘Theoretical analysis of numerical aperture increasing lens microscopy’” [J. Appl. Phys. 97, 053105 (2005)]
Authors: Ünlü M. S. , Ippolito S. B. , Vamivakas A. N. , Goldberg B. B.
Published: November 2006

We have identified that there is a small error in the original paper by Ippolito et al. [J. Appl. Phys. 97, 053105 (2005)] and we express our thanks to the authors of the comment for bringing it to our attention. However, the comment by Sheppard and Huat [J. Appl. Phys. 100, 086108 (2006)] has misinterpretations that lead to erroneous conclusions. We disagree with the statement of the comment that the conclusions on planar interface would carry through to the case of a numerical aperture increasing lens (NAIL). Our model calculates the wave aberration and provides valuable insight to the limitations of spatial resolution in the case of NAIL imaging and its dependence on various parameters, whereas angular spectrum method is not applicable to a spherical interface. The only significant error by Ippolito et al. is limited to an incorrect plot of Φ040 although the correct equation is given in the article.
A quantum mechanical/molecular dynamics/mean field study of acrolein in aqueous solution: Analysis of H bonding and bulk effects on spectroscopic properties
Authors: Brancato Giuseppe , Rega Nadia , Barone Vincenzo
Published: November 2006

A novel molecular dynamics methodology recently proposed by our group [Rega et al., Chem. Phys. Lett. 422, 367 (2006)], which is based on an integrated hybrid potential rooted in high level quantum mechanical methods using localized basis functions and nonperiodic boundary conditions, has been applied to study acrolein in aqueous solution. The solute structural rearrangement and its hydrogen-bonding pattern due to the interactions with water have been analyzed in some detail. Moreover, the solvent effects on the UV n→π∗ vertical transition and on the NMR C13 and O17 shielding constants of acrolein have been investigated theoretically by performing a posteriori quantum mechanical calculations on a statistically significant number of snapshots extracted from both gas-phase and aqueous solution simulations. Results show that such effective computational strategy can be successfully used to improve our understanding, at atomic level, of important spectroscopic observables.
Angular-momentum conservative smoothed particle dynamics for incompressible viscous flows
Authors: Hu X. Y. , Adams N. A.
Published: November 2006

Current smoothed particle dynamics discretizations for macroscopic and mesoscopic viscous flows usually do not conserve angular momentum. Angular-momentum conservation, however, potentially stabilizes the solution for long-time simulations. We show that a simple angular-momentum conservative formulation of the viscous force, which was proposed previously based on empirical findings, can be derived theoretically under the condition of incompressible flow. The properties of this formulation are asserted by numerical simulations of two-dimensional Taylor-Green flow.
A mixed composite spheres assemblage model for the transport properties of random heterogeneous materials with high contrasts
Authors: Stora E. , He Q.-C. , Bary B.
Published: November 2006

An exactly solvable assemblage mixing two types of coated spheres is proposed by exploiting the main ideas underlying the celebrated composite spheres assemblage of Hashin and Shtrikman [Z. Hashin and S. Shtrikman, J. Appl. Phys. 33, 3125 (1962)]. A simple estimate for the transport properties of random heterogeneous media, such as diffusivity, is derived from this mixed composite spheres assemblage (MCSA). Given the phase volume fractions, the obtained estimate depends only on one geometric parameter which accounts for the phase connectivity and whose variation allows the realization of any diffusivity ranging within the Hashin-Shtrikman bounds. For random heterogeneous media consisting of high contrast phases, the derived estimate has the capacity to capture the sudden variation of the effective conduction or diffusion coefficient due to a critical microstructure change. As an example of practical interest, the MCSA model is applied to estimate the diffusion properties of hardened cement pastes.
Enhancement of band edge luminescence in ZnSe nanowires
Authors: Philipose U. , Xu T. , Yang S. , Sun Ping , Ruda Harry E. , Wang Y. Q. , Kavanagh K. L.
Published: November 2006

In order to realize the full potential of nanowires for optical applications, it is essential to synthesize nanowires that can emit predominantly via band to band or band edge (BE) transitions. However, many compound semiconductor nanowires, irrespective of the method of their growth, contain a high density of native defects; these result in competing deep defect (DD) related emission, limiting their utility for optoelectronic device applications. The concentration of these native defect states depends on the gas phase stoichiometry. In this work, we report on the influence of gas phase stoichiometry on the structural and optical properties of single crystal zinc selenide (ZnSe) nanowires. We find that nanowires grown under stoichiometric conditions contain such defect states with associated weak BE emission and strong DD emission. However, nanowires grown under Zn-rich conditions were characterized by photoluminescence spectra dominated by strong BE emission while those grown under Se-rich conditions showed strong DD related emission. Hence, it is necessary to develop a strategy for enhancing the BE emission while simultaneously quenching the DD emission. We demonstrate a technique of postgrowth treatment that can effectively perform this function, and using this strategy the ratio of the BE/DD emission can be increased by a factor of several thousands, at least an order of magnitude higher than previously reported values. This reveals BE dominated photoluminescence in these nanowires and makes these nanowires suitable for developing future optoelectronic devices.