bluuebunny/crossref_metadata_2025 huggingface dataset:
Platelet‐activating factor type activity in plasma from patients with septicemia and other diseases
Authors: Heuer Hubert O. , Darius Harald , Lohmann Helmut F. , Meyer Juergen , Schierenberg Manuela , Treese Norbert
Published: February 2007

The purpose of the present study was to determine whether increased levels of platelet‐activating factor (PAF) type activity can be detected in plasma from patients with septicemia and other diseases. A level of PAF below 0.5 ng/mL of plasma was considered normal. We found that plasma from a patient with adverse anaphylactoidic reaction to intravenous analgetics contained 2.1 ng PAF/mL. In seven patients with septicemia, including urosepsis, endocarditis and peritonitis, and with positive blood culture, increased plasma PAF levels (1–20 ng PAF/mL) were observed. Other patients with clinical indications of septicemia had negative blood cultures and/or increased levels of C‐reactive protein (CRP). Yet, in the plasma from these patients, no increased PAF levels were detected under the assay conditions used. Two patients with allergic asthma, requiring treatment with steroids, had no measurable plasma PAF. In the plasma from a patient with idiopathic thrombocytopenic purpura (ITP) only an “endogenous” inhibitor of PAF induced platelet aggregation was initially observed. In spite of this, the patient responded to treatment with the PAF antagonist WEB 2086 with a dramatic increase in platelet count (Lohmannet al., Lancet ii, 1147, 1988). Thereafter, also increased PAF levels (3.3 ng PAF/mL) were detected in plasma, although some “endogenous” inhibitor of PAF was still present. In conclusion, increased PAF levels in plasma from patients support a role of PAF in certain human disease states, such as in anaphylactoid reaction, sepsis and septic shock. The type, relevance and specificity of endogenous inhibitors of PAF deserve further study.
Involvement of platelet‐activating factor in zymosan‐induced rat pleurisy
Authors: Imai Yohsuke , Hayashi Masahiko , Oh‐ishi Sachiko
Published: February 2007

The role of platelet‐activating factor (PAF) in inflammatory reactions was studied in zymosan‐induced rat pleurisy. Pleurisy was induced by injection of a 2% zymosan suspension into the pleural cavity of rats. The time course of pleural exudate accumulation, the exudation rate, and exudate leukocyte numbers were followed then for 96 hr. Peak pleural exudate accumulation was about 3 mL at 24 hr, whereas the exudation rate increased biphasically with peaks at 0.5 hr and 5 hr. The migration of leukocytes into the pleural cavity increased with time up to 48 hr. The polymorphonuclear leukocytes were the dominant white cells in the exudate between 5 and 16 hr, but mononuclear leukocytes started to outnumber them around 24 hr. Pretreatment with cyproheptadine (5 mg/kg), an inhibitor of both histamine and seotonin, significantly suppressed pleural fluid accumulation and the exudation rate at 0.5 hr. The PAF antagonist CV‐6209 (1 mg/kg) significantly suppressed pleural fluid accumulation and the exudation rate at both 0.5 and 5 hr. At either time point, the parameters were not suppressed by indomethacin. We detected PAF activity in the high‐performance liquid chromatography (HPLC) fraction (with a retention time corresponding to that of authentic PAF) of the exudates at 0.5 hr, 5 hr, and 16 hr using an aggregation bioassay with washed rabbit platelets. The results suggest that in zymosan‐induced rat pleurisy, histamine and/or serotonin are the main mediators of exudation at 0.5 hr and that PAF may be partly responsible for exudation at 0.5 hr and later at 5 hr to 16 hr.
Antitumor activity of ilmofosine (BM 41.440) in the3Lewis‐lung carcinoma model
Authors: Herrmann Dieter B. J. , Opitz Hans‐George , Munder Paul G.
Published: February 2007

Ilmofosine (1‐hexadecylthio‐2‐methoxymethyl‐1,3‐propanediol‐phosphocholine, BM 41.440) is a thioether phospholipid with cytostatic/cytotoxic properties. The antineoplastic activity of this compound was investigatedin vivo in the3Lewis‐lung carcinoma system.3Lewis lung tumor‐bearing C57Bl/6 mice were treated with 0.625 to 40 mg Il‐mofosine/kg per dayp.o. either from days 1 to 9 or from days 11 to 28 after intrafoot‐pad tumor cell inoculation. Ilmofosine caused a significant dose‐related response on tumor growth and metastases, expressed in terms of tumor diameter, tumor weight, survival time and number of metastases‐free animals as compared to sham‐treated and positive (cyclophosphamide) controls. The results suggest that direct cytostatic/cytotoxic effects, rather than immune‐modulatory mechanisms, preferentially contribute to the antitumor activity of Ilmofosinein vivo.
1‐β‐D‐arabinofuranosylcytosine conjugates of ether and thioether phospholipids. A new class of ara‐C prodrug with improved antitumor activity
Authors: Hong Chung Il , West Charles R. , Bernacki Ralph J. , Tebbi Cameron K. , Berdel Wolfgang E.
Published: February 2007

The 1‐β‐D‐arabinofuranosylcytosine (ara‐C) conjugates 1‐O‐alkyl (ether) and 1‐S‐alkyl (thioether) phospholipids, being analogues of ara‐CDP‐sn‐1,2‐O‐dipalmitoylglycerol (1), showed significant antitumor activity against L1210 and P388 leukemiain vivo. The more active conjugates include the 1‐O‐alkyl analogues, ara‐CDP‐rac‐1‐O‐hexadecyl‐2‐O‐palmitoylglycerol (2) and ara‐CDP‐rac‐1‐O‐octadecyl‐2‐O‐palmitoylglycerol (3), and the corresponding 1‐S‐alkyl analogues, ara‐CDP‐rac‐1‐S‐hexadecyl‐2‐O‐palmitoyl‐1‐thioglycerol (4) and ara‐CDP‐rac‐1‐S‐octadecyl‐2‐O‐palmitoyl‐1‐thioglycerol (5, Cytoros). The conjugates were formulated by sonication, in which the conjugates existed as discs (size 0.01–0.04 μ).. Among the conjugates of the three different phospholipids, the 1‐S‐alkyl analogues 4 and 5 displayed the strongest antitumor activity against L1210 leukemia in mice, followed by the 1‐O‐alkyl (2 and 3) and the 1‐O‐acyl (1) analogues. The 1‐S‐alkyl analogue 5 was considerably more effective than the 1‐O‐acyl analogue 1 against myelomonocytic WEHI‐3B leukemia in mice. Conjugate 5 (Cytoros) showed a significant therapeutic activity in mice with colon 26 carcinoma, M5076 sarcoma, and C‐1300 neuroblastoma. Furthermore, this agent inhibited liver metastases of M5076 sarcoma. Conjugates 3 and 5 also inhibited the metastasis of 3‐Lewis lung carcinoma to the lungs of mice. Cytoros (5) and its analogues, with other ether and thioether phospholipids, appear to offer increased therapeutic benefit to mice with tumors.
Induction of differentiation of human myeloid leukemia HL‐60 cells by novel nonphosphorus alkyl ether lipids
Authors: Honma Yoshio , Kasukabe Takashi , Hozumi Motoo , Akimoto Hiroshi , Nomura Hiroaki
Published: February 2007

We synthesized a new series of nonphosphorus alkyl ether glycerolipids, in which the 2‐acetyl group of platelet‐activating factor was replaced by a pyrimidin‐2‐yl group and the 3‐phosphocholine portion by anω‐(substituted ammonio)ethoxyethyl side‐chain including ω‐thiazolio‐, imidazolio‐and pyridinio groups with or without a carboxyl substituent, respectively (compound I–XI). Their effects on cell proliferation and differentiation of human myeloid leukemia HL‐60 cells were examined. Incubation of HL‐60 cells with these cationic and zwitterionic alkyl ether lipids inhibited proliferation of HL‐60 cells with IC50 values ranging from 10 to 500 ng/mL. The cells were induced by the lipids to differentiate into morphologically and functionally mature granulocytes. Among the compounds we tested, 1‐octadecyl‐2‐pyrimidinyl‐3‐[3‐(5‐carboxylatepenty)imidazolioethoxyethyl]glycerol (compound I) was the most effective in inducing differentiation of HL‐60 cells. Compound I showed on a molar basis, an inhibitory effect on the leukemic cells over 50 times greater than did 2‐(2‐dodecyloxyethoxy)ethyl 2‐pyridinioethyl phosphate, the antileukemic alkyl ether phospholipid.
Search for new industrial oils. XII. Fifty‐eight euphorbiaceae oils, including one rich in vernolic acid
Authors: Kleiman R. , Smith C. R. , Yates S. G. , Jones Quentin
Published: February 2007

Seed oil ofEuphorbia lagascae Spreng. contains 57% ofcis‐12,13‐epoxy‐cis‐9‐octadecenoic (vernolic) acid. The amt of trivernolin in the glycerides of this species indicates random or restricted random distribution of the vernolic acid.

Seed from 57 additional species in the Euphorbiaceae were analyzed for oil and protein contents and also for fatty acid composition of the oils. Iodine values (I.V.) of the oils ranged from 87舑221. Among these oils, samples were encountered with as much as 76% linolenic, 77% linoleic or 84% oleic acid.
The effect of temperature upon foam fractionation
Authors: Grieves R. B. , Bhattacharyya D.
Published: February 2007

An experimental investigation is presented of the effect of temp on the foam fractionation of the ethylhexadecyldimethylammonium bromide‐water system. Two feed concn, two foam heights, and a temp range of 14舑54C are included. For each fixed set of values of feed concn and of foam height, the greater and lesser coefficients of fractionation are both increasing functions of temp. The effect of a variation in temp on the greater coefficient is more pronounced for more dilute feed solutions, and at greater foam heights. The effect of a temp change on the lesser coefficient is more pronounced for more concd feed solutions and is not related to foam height. At any fixed temp, an increase in feed concn at constant foam height generally decreases the greater coefficient and decreases the lesser coefficient. An increase in foam height at constant feed concn increases both coefficients. The greater and lesser coefficients may be related to temp by power equations with 5% accuracy. The above results may be explained qualitatively on the basis of the response of foam stability and drainage to temp.
A colorimetric method for the determination of parts/million of nonionic surfactants
Authors: Greff R. A. , Setzkorn E. A. , Leslie W. D.
Published: February 2007

A method for the determination of nonionics in low concn (0舑20 ppm) has been developed. This method is based on the formation of a blue complex between ammonium cobaltothiocyanate reagent and a polyethoxylated compound. This complex is extracted into benzene from a saturated salt solution and measured with a spectrophotometer at 320 mƁ. The absorbance reading is compared to a standard.

The method requires only a single extraction and no preliminary concn step is necessary. It is sensitive to polyethoxylated compounds containing three or more moles of ethylene oxide. We have used this method to detect as little as 0.01 mg of nonionic in 100 ml of sample (0.1 ppm). Reaction conditions, sensitivity differences between compounds, interferences and suitability for use in biodegradation studies have been investigated. The accuracy and repeatability of this method is ŷ3% relative at 20 ppm concn.
The energetics of micellar solubilization
Authors: Mankowich A. M.
Published: February 2007

Micellar solubilization, an action of the detergency mechanism, is considered from the stand‐point of quasi‐thermodynamics. The basis of the approach was suggested by the similarity of micellar solubilization and Freundlich adsorption isotherms. Free energy change (खG), heat of solubilization (खH) and change in entropy (खS) for the micellar solubilization of Orange OT are calculated using two‐phase theory and the Gibbs‐Helmholtz equation. It is postulated that the dye concn in the solution (monomer) phase is that at the critical micelle concn. The dye concn in the solubilized phase is computed for the dye‐penetrated portion of the micellar volume. Calculated values of खG in anionic and nonionic surfactants are of the order of magnitude of a physical adsorption. The positive खH values indicate the process is not an adsorption. The positive खS values point to increased randomness or possibly to decreased energy effects due to iceberg water molecule structure surrounding the hydrophobic dye molecules. The loss of the water structure around the latter in the solubilization process would result in their acquiring increased configu‐rational entropy.
Effect of unusual acids on selected seed oil analyses
Authors: Wolff I. A. , Miwa T. K.
Published: February 2007

In the course of chemical compositional studies on seed oils from more than 2600 species of uncultivated plants, a number of new acids were isolated and structurally characterized at our laboratory. Also included in the studies were many fatty acids previously identified but not widely distributed or readily available. Oils containing unusual functional groups often gave unexpected responses to analytical procedures in frequent use. To exemplify the analytical results, data are presented relative to behavior of oils containing oxygenated fatty acids, cyclopropene rings, unusual types and positions of unsaturation, differing chain length, and sundry combinations of these, in the following procedures: Determinatio of polyunsaturated acids by ultraviolet spectrophotometry; iodine value versus refractive index plot to single out unusual oils; oxirane oxygen by HBr titration; gas‐liquid chromatography; infrared, and nuclear magnetic resonance spectroscopy; and lipoxidase assay. Preliminary experimentation on an automatic analytical hydrogenation apparatus indicates good potential, in its aplication to both usual and unusual oils, for a rapid determination of total unsaturation with acceptable accuracy and precision.
A review of antioxidant analysis in food products
Authors: Stuckey B. N. , Osborne C. E.
Published: February 2007

To permit proper usage of antioxidants by the food processor and permit control under applicable governmental regulations, it is necessary to have adequate analytical methods. Such methods should both positively identify and provide a quantitative assay for the additive. Due to the complex nature of foods, analysis of an antioxidant in the very small quantities used presents a very real problem. Solvent extraction and/or steam distillation techniques are employed to separate the antioxidants from the food. Ultraviolet spectra, gas chromatography and colorimetric techniques are used to identify and determine the quantity of each antioxidant present. Slight variations are necessary for each type of food.
Increasing Utilization of Cancer Genetic Counseling Services Using a Patient Navigator Model
Authors: Rahm Alanna Kulchak , Sukhanova Anna , Ellis Jennifer , Mouchawar Judy
Published: February 2007

Rarely has utilization of genetic counseling for Hereditary Breast and Ovarian Cancer (HBOC) been studied separately from utilization of testing. At Kaiser Permanente Colorado, consistently only 30% of all members referred for HBOC attend genetic counseling. To increase the volume of genetic counseling appointments, a patient navigator approach was pilot tested in a randomized‐controlled trial over 3 months. A total of 125 members were referred for HBOC genetic counseling (55 randomized to PN, 70 randomized to usual care). Utilization of referrals for Navigator‐assisted members was 44%, compared to 31% in the usual care arm (p=0.16). The patient navigator significantly decreased time to appointment, with over 80% of Navigator‐assisted members seen for genetic counseling less than three months from referral date, compared to 32% in usual care (p=0.002). patient navigator assistance shortens time from referral to appointment for HBOC genetic counseling, and may increase utilization of such services.
Prograde amphibolite facies to ultrahigh‐pressure transition along Nordfjord, western Norway: Implications for exhumation tectonics
Authors: Young David J. , Hacker Bradley R. , Andersen Torgeir B. , Corfu Fernando
Published: February 2007

The Nordfjord area of western Norway hosts one of the best known provinces of ultrahigh‐pressure (UHP) rocks in the world, yet the nature of the transition from the UHP rocks into surrounding amphibolite‐facies crust has remained unclear. New thermobarometry of phengite‐ and kyanite‐bearing eclogites shows that this transition is unbroken by major structures: the pressure and temperature gradient increases smoothly over a horizontal distance of ∼20 km, from high‐pressure amphibolite facies (∼1.5 GPa/600–700°C) through quartz eclogite (∼2.4 GPa/600°C) into UHP eclogite (>2.7 GPa/700°C). These data support a model in which the Norwegian UHP province remained attached to lower pressure crust during exhumation. This requires that a large area of the Western Gneiss Region was metamorphosed and exhumed ∼60 km through the mantle, as a relatively coherent body.
Atlantic water circulation over the Mendeleev Ridge and Chukchi Borderland from thermohaline intrusions and water mass properties
Authors: Woodgate Rebecca A. , Aagaard Knut , Swift James H. , Smethie William M. , Falkner Kelly K.
Published: February 2007

Hydrographic and tracer data from 2002 illustrate Atlantic water pathways and variability in the Mendeleev Ridge and Chukchi Borderland (CBLMR) region of the Arctic Ocean. Thermohaline double diffusive intrusions (zigzags) dominate both the Fram Strait (FSBW) and Barents Sea Branch Waters (BSBW) in the region. We show that details of the zigzags' temperature‐salinity structure partially describe the water masses forming the intrusions. Furthermore, as confirmed by chemical tracers, the zigzags' peaks contain the least altered water, allowing assessment of the temporal history of the Atlantic waters. Whilst the FSBW shows the 1990s warming and then a slight cooling, the BSBW has continuously cooled and freshened over a similar time period. The newest boundary current waters are found west of the Mendeleev Ridge in 2002. Additionally, we show the zigzag structures can fingerprint various water masses, including the boundary current. Using this, tracer data and the advection of the 1990s warming, we conclude the strongly topographically steered boundary current, order 50 km wide and found between the 1500 m and 2500 m isobaths, crosses the Mendeleev Ridge north of 80°N, loops south around the Chukchi Abyssal Plain and north around the Chukchi Rise, with the 1990s warming having reached the northern (but not the southern) Northwind Ridge by 2002. Pacific waters influence the Atlantic layers near the shelf and over the Chukchi Rise. The Northwind Abyssal Plain is comparatively stagnant, being ventilated only slowly from the north. There is no evidence of significant boundary current flow through the Chukchi Gap.
Stoichiometry of CH4 and CO2 flux in a California rice paddy
Authors: McMillan Andrew M. S. , Goulden Michael L. , Tyler Stanley C.
Published: February 2007

Rice paddies contribute significantly to the atmospheric burden of CH4 but may also sequester atmospheric CO2. Previous studies based on putative relationships between net CO2 exchange and CH4 emissions have concluded that globally significant amounts of carbon can be stored in rice paddy soils. However, the annual ratio of CH4 emissions to net CO2 exchange has not previously been measured. We simultaneously measured the net exchange of CO2 (FCO2) by eddy covariance and the CH4 emission rate (FCH4) using a combination of a flux gradient technique and weekly chamber sampling. During rice growth, FCH4 was 1.9% to 2.4% of net carbon uptake (mole per mole). FCO2 closely followed biomass accumulation. In contrast, FCH4 increased during vegetative rice growth and decreased over the ripening and reproductive phases of rice growth, suggesting that the plants release substrate for methanogenesis early in the season. CH4 emissions represented 4.8% to 5.6% of the net CO2 uptake when summed over an entire year (including a 20‐week period over which the field was unplanted and flooded). Assuming harvested rice is remineralized within 1 year, the remaining 0.67 t C ha−1 that was sequestered by the paddy potentially offsets the radiative forcing of the emitted CH4 by 26% to 31%. The ratio of FCH4 to FCO2 varied widely over the course of a year depending on management practices in a specific field. The results reported here emphasize the importance of year‐round measurements to obtain a reliable estimate of CH4/CO2 exchange stoichiometry.
Crustal architecture of SW Yukon, northern Cordillera: Implications for crustal growth in a convergent margin orogen
Authors: Johnston Stephen T. , Canil Dante
Published: February 2007

A structural analysis of southwest Yukon based on mapping and the compilation of structural data is used to determine if convergent margin orogenesis has contributed to westward growth of North America. The crust of SW Yukon is tilted regionally to the ESE, exposing a >20 km section of crust. A down‐plunge profile is used to determine the geometry and evolution of the crust. Four lithotectonic packages are recognized. These are, from east to west, (1) the Triassic‐Jurassic Whitehorse Trough assemblage of arc and arc‐derived volcanic and sedimentary rocks, (2) the Devonian‐Mississippian continental Aishihik metamorphic assemblage, (3) the Jurassic‐Cretaceous metapelitic Kluane metamorphic assemblage, and (4) the Jurassic‐Cretaceous Dezadeash Group of arc‐marginal graywackes. The Early Jurassic Aishihik and Tertiary Coast plutonic suites are major synkinematic tabular intrusive complexes that facilitated crustal growth by subcretion of the Aishihik metamorphic assemblage beneath the Whitehorse Trough and the Kluane metamorphic assemblage and Dezadeash Group beneath Aishihik metamorphic assemblage and overlying strata, respectively. Early Jurassic crustal growth gave rise to a crust that became older and more radiogenic at depth; Tertiary growth gave rise to a crust that became younger and less radiogeneic at depth. Crustal growth by subcretion necessarily involved the removal of the lower crust and mantle of the upper plate. The lithotectonic assemblages and the tabular intrusive complexes along which they were assembled are identifiable in the seismic reflection data along Slave Northern Cordillera Lithosphere Evolution Project (SNORCLE) line 3 and are broadly imaged by a regional electromagnetic (EM) survey. The ACCRETE program to the south has documented a comparable and directly correlative crustal geometry across the Great Tonalite Sill. Our findings are inconsistent with crustal growth models of tectonic flakes being emplaced onto an autochthonous lower crust and mantle. Instead our findings support models (Lithoprobe Vancouver Island, and ACCRETE) of crustal growth at convergent margins as resulting from synmagmatic subcretion.
Studies of the magnetization reversal process driven by an oscillating field
Authors: Lee Hwee Kuan , Yuan Zhimin
Published: February 2007

Magnetic recording based on coherent rotation is hitting its physical limitations. An alternative of driving magnetization reversal using an oscillating field has been proposed. We performed systematic studies of the magnetization reversal process in the presence of oscillating fields. The oscillating field reduces the coercivity significantly, and for isolated particles, we observed consistent results reported previously. For a circularly polarized field, we obtained a hysteresis loop that exhibits a behavior that would not be observed in the absence of oscillating fields.
Fluid-structure interaction in atomic force microscope cantilever dynamics and thermal response
Authors: Cole D. G. , Clark R. L.
Published: February 2007

This paper discusses the effects of fluid loading on structures at low Reynolds numbers, a regime commonly found in the case of atomic force microscope cantilevers. In order to provide insight to the problem, the effect of fluid loading is analyzed from a feedback/systems approach, a perspective that considers the response of the fluid loaded system using the open-loop characteristics of the in vacuo cantilever and hydrodyamic effects. Increased mass ratio is shown to increase the bandwidth of the fluid-structure feedback loop with corresponding decrease in system quality for high fluid loading. The nondimensional natural frequency plays the role of a Reynolds number and determines the phase margin of the system. An analysis of the frequency response of the fluid loaded system, using the fluctuation-dissipation theorem, shows the fluctuating force is not spectrally white, but is related to the imaginary part of the hydrodynamic function. The mean potential energy of the cantilever is shown to be 12kBT, however, the kinetic energy is shown to be less than this value, decreasing with increasing fluid loading.
Magnetotransport properties of epitaxial strain-less La0.7Ba0.3MnO3 thin films
Authors: Orgiani P. , Guarino A. , Aruta C. , Adamo C. , Galdi A. , Petrov A. Yu. , Savo R. , Maritato L.
Published: February 2007

We have fabricated La0.7Ba0.3MnO3 (LBMO) thin films by a pulsed laser deposition technique using a low partial pressure (10−2 mbar) of O2+5% O3. In order to study the role of oxygen content in the transport properties, the temperature dependence of the resistivity has been measured as a function of the temperature and the time of a post-annealing process. Strain-less LBMO thin films deposited on SrTiO3 substrates show a metal insulator transitions temperature TMI≃345 K (equal to that found in bulk material). A T2.5-power law has been measured in R(T) at low temperature, supporting the disorder-induced single magnon scattering scenario. At high temperature (T>TMI) an activated behavior characteristic of polaronic carriers has been measured. Magnetotransport properties show a metal-like behavior and a negative magnetoresistance (MR) in the whole temperature range. With an external magnetic field of 70 kOe, the MR reaches the maximum value of 170% at about 320 K.
Regular silicon pillars and dichroic filters produced via particle-imprinted membranes
Authors: Ladenburger Andreas , Reiser Anton , Konle Johannes , Feneberg Martin , Sauer Rolf , Thonke Klaus , Yan Feng , Goedel Werner A.
Published: February 2007

We have produced regular silicon pillar arrays and porous gold films on the 100 nm scale without any optical or e-beam lithography. Using particle-assisted wetting we produced a nanoporous polymer membrane on silicon. The membrane incorporated a regular array of pores generated by embedding silica particles in an organic liquid and subsequently removing the particles after polymerization of the liquid. Gold vapor was deposited onto the silicon wafer coated by the porous polymer structure. This process created an array of gold dots on the substrate at the bottom of the pores, and at the same time, a sievelike porous gold layer on top of the polymer matrix. The top layer was lifted off and used as an optical short-pass filter. After removal of the polymer membrane, the remaining gold dot pattern on the substrate served as a mask in a deep reactive ion etching process. We obtain large-area arrays of silicon nanopillars up to 1.5 μm in height and below 200 nm in diameter.
Ewald sums for Yukawa potentials in quasi-two-dimensional systems
Authors: Mazars Martial
Published: February 2007

In this article, the author derive Ewald sums for Yukawa potential for three-dimensional systems with two-dimensional periodicity. This sums are derived from the Ewald sums for Yukawa potentials with three-dimensional periodicity [G. Salin and J.-M. Caillol, J. Chem. Phys.113, 10459 (2000)] by using the method proposed by Parry for the Coulomb interactions [D. E. Parry, Surf. Sci.49, 433 (1975); 54, 195 (1976)].
Synthesis of cubic boron nitride films with mean ion energies of a few eV
Authors: Teii Kungen , Yamao Ryota , Yamamura Toshifumi , Matsumoto Seiichiro
Published: February 2007

The lowest threshold energy of ion bombardment for cubic boron nitride (cBN) film deposition is presented. cBN films are prepared on positively biased Si (100) substrates from boron trifluoride (BF3) gas in the high-density source region of an inductively coupled plasma with mean ion impact energies from 45 down to a few eV or less. The great decrease in the threshold ion energy is mainly attributed to specific chemical effects of fluorine as well as high ion-to-boron flux ratios. The results show evidence for the existence of a way to deposit cBN films through quasistatic chemical processes under ultralow-energy ion impact.
Weak localization and correlation effects in thin-film degenerate n-type silicon
Authors: Troup A. S. , Wunderlich J. , Williams D. A.
Published: February 2007

The magnetoconductance of thin-film n-type silicon has been studied in order to provide insight into the low-temperature behavior of recent silicon-based semiconductor-metal hybrid structures. There is considerable interest in such structures as potential candidates for creating nonmagnetic read-head sensors for ultrahigh-density recording. The magnetoconductance of thin-film silicon was therefore analyzed as a function of magnetic field orientation at temperatures ranging from T=4.2 to 300 K. At low temperatures, the magnetoconductance consists of two components that are attributed to weak localization and correlation effects. Surprisingly, the thin-film transport properties behave two-dimensionally for the localization contribution, whereas the correlation contribution is isotropic. Similar two-dimensional localization behavior has previously been reported for silicon inversion layers but was not expected for silicon systems with a finite thickness. An analysis of the magnetoconductance as a function of magnetic field orientation has verified that the localization contribution depends only on the perpendicular to plane component of the field. The Hall coefficient was observed to vary with magnetic field, providing further evidence for a magnetoconductance governed by electron-electron interactions. Fitting of the data at T=4.2 K and for low magnetic fields provided values for the localization parameter α, the inelastic scattering time τi, and the two-dimensional effective electron screening constant F̃σ.
Diffusion of guest molecules in MCM-41 agglomerates
Authors: Valiullin Rustem , Dvoyashkin Muslim , Kortunov Pavel , Krause Cordula , Kärger Jörg
Published: February 2007

The pulsed field gradient nuclear magnetic resonance method has been used to study self-diffusion of cyclohexane in a commercial MCM-41 material at different external gas pressures from zero to saturated vapor pressure. It is found that the effective diffusivities exhibit three different regions with increasing pressure: decrease at low pressures, a sudden drop at intermediate pressures, and increase at higher pressures. In addition, in the region of irreversible adsorption (hysteresis loop) the diffusivities are also found to differ on the adsorption and the desorption branches. A simple analytical model taking account of different molecular ensembles with different transport properties due to the complex architecture of the porous structure is developed which provides a quantitative prediction of the experimental data. The analysis reveals that the effective diffusivity is predominantly controlled by the adsorption properties of the individual mesoporous MCM-41 crystallites which, in combination with high transport rates, provide a simple instrument for fine tuning of the transport properties by a subtle variation of the external conditions.
Periodic ordering of random surface nanostructures induced by femtosecond laser pulses on metals
Authors: Vorobyev A. Y. , Makin V. S. , Guo Chunlei
Published: February 2007

In this paper, we performed a detailed study of the formation of femtosecond laser-induced periodic surface structures (LIPSSs) on platinum and gold at near-damage threshold fluences. We find a unique type of LIPSS entirely covered with nanostructures. A distinctive feature of the nanostructure-covered LIPSS is that its period is appreciably less than that of the regular LIPSS. We show that the reduced period is caused by an increase of the real part of the effective refractive index of the air-metal interface when nanostructures develop and affect the propagation of surface plasmons.
Comment on “Mechanism for the increase of indium-tin-oxide work function by O2 inductively coupled plasma treatment” [J. Appl. Phys. 95, 586 (2004)]
Authors: Lin Yow-Jon
Published: February 2007

A high work function on indium tin oxide (ITO) surfaces with O2 inductively coupled plasma (ICP) treatment was obtained in the paper: “Mechanism for the increase of indium tin oxide work function by O2 inductively coupled plasma treatment” [Lee et al., J. Appl. Phys. 95, 586 (2004)]. They attributed this to the higher work function of the larger upward band bending and the larger electron affinity of the ITO near the surface by the ICP treatment. In this Comment, we indicate the mistake in their analysis of the observed result by synchrotron radiation photoemission spectroscopy.
New class of dynamics in concentrated polymer gels
Authors: Svanberg C. , Uematsu T. , Berntsen P. , Jacobsson P.
Published: February 2007

We show that concentrated poly(methyl methacrylate) solution exhibits a new class of coupled dynamics, which can be regarded as an intermediate between the collective diffusion of solutions and the structural relaxations of glasses. This class of dynamics have a relaxation rate that is directly proportional to the wave vector. The transition from diffusive to coupled collective dynamics occurs at smaller length scales with increasing polymer concentration and decreasing temperature. The experimental observations can be understood by considering the contributions from physical cross-links interconnected by stiff polymer segments.
Animal magnetocardiography using superconducting quantum interference device gradiometers assisted with magnetic nanoparticle injection: A sensitive method for early detecting electromagnetic changes induced by hypercholesterolemia
Authors: Wu C. C. , Hong B. F. , Wu B. H. , Yang S. Y. , Horng H. E. , Yang H. C. , Tseng W. Y. Isaac , Tseng W. K. , Liu Y. B. , Lin L. C. , Lu L. S. , Lee Y. H.
Published: February 2007

In this work, the authors used a superconducting quantum interference device (SQUID) magnetocardiography (MCG) system consisted of 64-channel low-transition-temperature SQUID gradiometers to detect the MCG signals of hepercholesterolemic rabbits. In addition, the MCG signals were recorded before and after the injection of magnetic nanoparticles into the rabbits’ ear veins to investigate the effects of magnetic nanoparticles on the MCG signals. These MCG data were compared to those of normal rabbits to reveal the feasibility for early detection of the electromagnetic changes induced by hypercholesterolemia using MCG with the assistance of magnetic nanoparticle injection.
Interactions between sterically stabilized nanoparticles in supercritical fluids: A simulation study
Authors: Patel N. , Egorov S. A.
Published: February 2007

The authors report a simulation study of the interaction between gold nanoparticles stabilized with both linear and branched alkane chains in supercritical ethane. In agreement with experimental and previous theoretical work, the authors find that increasing solvent density and making ligands more branched make the nanoparticle interaction more repulsive. These findings are analyzed in terms of the extent of the chain interdigitation and chain-solvent interaction energy.
Vacuum heating versus skin layer absorption of intense femtosecond laser pulses
Authors: Bauer D. , Mulser P.
Published: February 2007

The crossing of the narrow skin layer in solid targets by electrons in a time shorter than a laser cycle represents one of the numerous collisionless absorption mechanisms of intense laser-matter interaction. This kinetic effect is studied at normal and oblique laser beam incidence and particle injection by a test particle approach in an energy interval extending into the relativistic domain. Three main results obtained are the strong dependence of the energy gain by the single particle on the instant of injection relative to the phase of the light wave, the reflection of the particles primarily contributing to absorption well in front of the target rather than in the Debye layer, and the low degree of absorption hardly exceeding the 10% limit. The simulation results offer a more unambiguous interpretation of the absorption mechanism often referred to as “vacuum heating.” In particular, it is clearly revealed that the absorption in the vacuum region prevails on that originating from the skin layer. Relativistic ponderomotive effects are also tested, however their contribution to absorption is not significant.
Viewing angle switching of vertical alignment liquid crystal displays by controlling birefringence of homogenously aligned liquid crystal layer
Authors: Jeong Eun , Lim Young Jin , Rhee John Moon , Lee Seung Hee , Lee Gi-Dong , Park Kyoung Ho , Choi Hyun Chul
Published: February 2007

Viewing angle switching from a wide viewing angle to a narrow viewing angle has been studied. Conventional multidomain vertical alignment (VA) mode offers the advantages of a high contrast ratio (CR) not only in the front view but also in the wide viewing directions only if compensation films such as a negative C plate and a positive A plate are used. The positive A plate can be replaced by a homogeneous aligned (HA) liquid crystal layer, and the retardation of the HA layer at the off axis can be controlled by applying an electric field while keeping the retardation value at zero in the normal direction. Consequently, the viewing angle range of a VA device can be controlled from a wide viewing mode (over 170° in terms of CR=10) to a narrow viewing angle mode (approximately 60° in terms of CR=2) in the horizontal direction while keeping a high image quality at the normal direction.
Electrostatic potential behind a macroparticle in a drifting collisional plasma: Effect of plasma absorption
Authors: Chaudhuri M. , Khrapak S. A. , Morfill G. E.
Published: February 2007

The electric field and potential behind a small absorbing body (dust grain) at floating potential has been calculated analytically in a highly collisional drifting plasma. Linear plasma response formalism has been used and main attention has been focused on the effect of plasma absorption on the grain. It is shown that the long-range asymptote of the electric field is dominated by the effect of absorption and is always negative. Depending on plasma parameters, the electric field at intermediate distances can either increase monotonically or exhibit one maximum and one minimum. It can achieve positive values in certain parameter regimes, which indicates the possibility of electrostatic attraction between the grains aligned parallel to the flow. The obtained results can be important for understanding of the binary grain interactions in complex plasmas at elevated pressures.
Exact and quasiexact solvability of second order superintegrable quantum systems. II. Relation to separation of variables
Authors: Kalnins E. G. , Miller W. , Pogosyan G. S.
Published: February 2007

We make explicit the intimate relationship between quasiexact solvability, as expounded, for example, by Ushveridze [Quasi-exactly Solvable Models in Quantum Mechanics (IOP, Bristol, 1993)], and the technique of separation of variables as it applies to specific superintegrable quantum Hamiltonians. It is the multiseparability of superintegrable systems that forces the existence of interesting families of polynomial solutions characteristic of quasiexact solvability that enables us to solve these systems in distinct ways and that gives us the basis of a classification theory. This connection is generalized in terms of the understanding of the role of finite solutions of quantum Hamiltonians.
Dislocation annihilation in regrown GaN on nanoporous GaN template with optimization of buffer layer growth
Authors: Soh C. B. , Hartono H. , Chow S. Y. , Chua S. J. , Fitzgerald E. A.
Published: February 2007

Nanoporous GaN template has been fabricated by electrochemical etching to give hexagonal pits with nanoscale pores of size 20–50nm in the underlying grains. The effect of GaN buffer layer grown at various temperatures from 650to1015°C on these as-fabricated nanopores templates is investigated by transmission electron microscopy. The buffer layer grown at the optimized temperature of 850°C partially fill up the pores and voids with annihilation of threading dislocations, serving as an excellent template for high-quality GaN growth. This phenomenon is, however, not observed for the samples grown with other temperature buffer layers. Micro-Raman measurements show significant strain relaxation and improvement in the crystal quality of the overgrown GaN layer on nanoporous GaN template as compared to overgrown on conventional GaN template.
Intense greenish emission from d0 transition metal ion Ti4+ in oxide glass
Authors: Meng Xiangeng , Tanaka Katsuhisa , Fujita Koji , Murai Shunsuke
Published: February 2007

Ti 4 + -doped oxide glass is revealed to yield intense greenish emission by excitations with ultraviolet (UV) light and near-infrared femtosecond pulsed laser (NIFPL). The emission profile obtained by UV excitation can be well traced by NIFPL. Compared with Ta5+-doped oxide glasses reported previously, Ti4+-doped glasses exhibit distinctive characteristics in optical absorption, excitation, and emission spectra, indicating that intense tunable emissions can be readily achieved by selecting nd0 ions as dopants in glasses. The glass materials containing nd0 ions are expected to find applications in high density optical storage and three-dimensional color displays.
Measured limits of detection based on thermal-mechanical frequency noise in micromechanical sensors
Authors: Stievater T. H. , Rabinovich W. S. , Papanicolaou N. A. , Bass R. , Boos J. B.
Published: February 2007

The authors have fabricated and tested all-optical micromechanical resonators that sense the presence of analyte molecules by monitoring the shift in the resonant frequency of a mechani-cal mode of vibration. An analysis of the measured frequency noise at the fundamental flexural mode shows that it is dominated by thermal-mechanical noise. This result demonstrates that thermal-mechanical frequency noise can set the limit of detection in actual micromechanical or nanomechanical resonance-based sensors.
Atmospheric-pressure argon/oxygen plasma-discharge source with a stepped electrode
Authors: Lim Jin-Pyo , Uhm Han S. , Li Shou-Zhe
Published: February 2007

The nonequilibrium glow discharge in argon mixed with oxygen at atmospheric pressure was generated in a parallel plate reactor with a stepped electrode powered by a 13.56MHz radio-frequency power supplier. The stepped-electrode reactor consists of a narrow and wide gap structure. A strong electric field occurred at the narrow gap region preionizes Ar∕O2 gas and assists to generate a large volumetric plasma in the wide gap region. Therefore, the stepped-electrode reactor makes it easy to operate Ar∕O2 glow discharge, providing a stable, uniform, and broad plasma jet at atmospheric pressure.
Thermodynamic analysis of progesterone receptor–promoter interactions reveals a molecular model for isoform-specific function
Authors: Connaghan-Jones Keith D. , Heneghan Aaron F. , Miura Michael T. , Bain David L.
Published: February 2007

Human progesterone receptors (PR) exist as two functionally distinct isoforms, PR-A and PR-B. The proteins are identical except for an additional 164 residues located at the N terminus of PR-B. To determine the mechanisms responsible for isoform-specific functional differences, we present here a thermodynamic dissection of PR-A–promoter interactions and compare the results to our previous work on PR-B. This analysis has generated a number of results inconsistent with the traditional, biochemically based model of receptor function. Specifically, statistical models invoking preformed PR-A dimers as the active binding species demonstrate that intrinsic binding energetics are over an order of magnitude greater than is apparent. High-affinity binding is opposed, however, by a large energetic penalty. The consequences of this penalty are 2-fold: Successive monomer binding to a palindromic response element is thermodynamically favored over preformed dimer binding, and DNA-induced dimerization of the monomers is largely abolished. Furthermore, PR-A binding to multiple PREs is only weakly cooperative, as judged by a 5-fold increase in overall stability. Comparison of these results to our work on PR-B demonstrates that whereas both isoforms appear to have similar DNA binding affinities, PR-B in fact has a greatly increased intrinsic binding affinity and cooperative binding ability relative to PR-A. These differences thus suggest that residues unique to PR-B allosterically regulate the energetics of cooperative promoter assembly. From a functional perspective, the differences in microscopic affinities predict receptor–promoter occupancies that accurately correlate with the transcriptional activation profiles seen for each isoform.
Light-powering
Escherichia coli
with proteorhodopsin
Authors: Walter Jessica M. , Greenfield Derek , Bustamante Carlos , Liphardt Jan
Published: February 2007

Proteorhodopsin (PR) is a light-powered proton pump identified by community sequencing of ocean samples. Previous studies have established the ecological distribution and enzymatic activity of PR, but its role in powering cells and participation in ocean energy fluxes remains unclear. Here, we show that when cellular respiration is inhibited by depleting oxygen or by the respiratory poison azide,
Escherichia coli
cells expressing PR become light-powered. Illumination of these cells with light coinciding with PR's absorption spectrum creates a proton motive force (pmf) that turns the flagellar motor, yielding cells that swim when illuminated with green light. By measuring the pmf of individual illuminated cells, we quantify the coupling between light-driven and respiratory proton currents, estimate the Michaelis–Menten constant (
K
m
) of PR (10
3
photons per second/nm
2
), and show that light-driven pumping by PR can fully replace respiration as a cellular energy source in some environmental conditions. Moreover, sunlight-illuminated PR
+
cells are less sensitive to azide than PR
−
cells, consistent with PR
+
cells possessing an alternative means of maintaining cellular pmf and, thus, viability. Proteorhodopsin allows
Escherichia coli
cells to withstand environmental respiration challenges by harvesting light energy.
Natural Lifetimes and Hyperfine Structure for K39in the 5p2P3/2and 6p2P3/2Levels of the KI Spectrum by Resonance Scattering of Light
Authors: S Svanberg
Published: February 2007

The hyperfine coupling constants and the natural radiative lifetimes of the 5p2P3/2and 6p2P3/2levels of K39were determined in a level crossing experiment on an enriched K39sample in a sealed-off resonance cell. The following results were obtained:

a(5p2P3/2) = 1.973 (12) MHza(6p2P3/2) = 0.886 (8) MHzb(5p2P3/2) = 0.870 (18) MHzb(6p2P3/2) = 0.370 (15) MHzτ(5p2P3/2) = 133 (3) nsτ(6p2P3/2) = 310 (15) ns

Considering the influence of core polarization on the magnetic hyperfine interaction and applying a Sternheimer correction, fairly consistent values of the electric quadrupole momentQare obtained from the first three levels of thenp2P3/2sequence. We findQ(K39) = +0.059 (6) barn.
Automatic correspondence of tags and genes (ACTG): a tool for the analysis of SAGE, MPSS and SBS data
Authors: Galante Pedro A. F. , Trimarchi Jeff , Cepko Constance L. , de Souza Sandro J. , Ohno-Machado Lucila , Kuo Winston P.
Published: February 2007

Summary: A critical step in any SAGE, MPSS and SBS data analysis is tag-to-gene assignment. Current available tools are limited by a tag-by-tag annotation process and/or do not provide the dataset that is used to produce a complete tag-to-gene mapping. We developed ACTG, a web-based application that allows a large-scale tag-to-gene mapping using several reference datasets. ACTG can annotate SAGE (14 or 21 bp), MPSS (17 or 20 bp) and SBS (16 bp) data for both human and mouse organisms.

Availability:  http://retina.med.harvard.edu/ACTG/

Contact:  pgalante@ludwig.org.br

Supplementary information: Supplementary data are available at Bioinformatics online.