Underwater ambient noise on the Chukchi Sea continental slope from 2006-2009

From September 2006 to June 2009, an autonomous acoustic recorder measured ambient noise north of Barrow, Alaska on the continental slope at 235 m depth, between the Chukchi and Beaufort Seas. Mean monthly spectrum levels, selected to exclude impulsive events, show that months with open-water had the highest noise levels (80-83 dB re: 1 μPa(2)/Hz at 20-50 Hz), months with ice coverage had lower spectral levels (70 dB at 50 Hz), and months with both ice cover and low wind speeds had the lowest noise levels (65 dB at 50 Hz). During ice covered periods in winter-spring there was significant transient energy between 10 and 100 Hz from ice fracture events. During ice covered periods in late spring there were significantly fewer transient events. Ambient noise increased with wind speed by ~ 1 dB/m/s for relatively open-water (0%-25% ice cover) and by ~ 0.5 dB/m/s for nearly complete ice cover (> 75%). In September and early October for all years, mean noise levels were elevated by 2-8 dB due to the presence of seismic surveys in the Chukchi and Beaufort Seas.     

Die Anwendung des Quantimet zur Ätzgrubendichtebestimmung an Silizium-Einkristallen

A quantitative estimation of the structure of etched silicon crystals is possible with the microscope Quantimet by a fast counting the number of particles, i.e. etch pits on {111}-planes. Boundary conditions of the measuring technique are the requisite size of the etch pits of from > 3 … 5 μm, a plane specimen surface, the correct optical magnification, threshold and acceptance width. Sources of errors due to the structure result from the overlap of etch pits at dislocation densities > 10⁴ cm⁻² which leads to an underestimation of the number of etch pits because of the reduced signal output. An overestimation is most caused by an unwished contrast in the surface which yields additional signal outputs. The errors will be eliminated by using a calibration curved. Due to the short time which is necessary for counting, the Quantimet is well suitable for routine testings and for quantitative evaluation of the structure defects (etch pit density) in silicon, including consideration of possible errors.     

Characterization of thin Ta-Si-Nx layers of different nitrogen content using XPS, UPS and STM

Reactively sputtered Ta-Si-N_x barrier systems of different nitrogen content on copper were investigated by photoelectron spectroscopy (XPS, UPS) and scanning tunnelling microscopy (STM). The measured photoelectron spectra (excitation He-I) showed a clear dependence of the electron state density near the Fermi edge on the content of nitrogen. These results correlate with the I(U) characteristics of the STM measurements and the electrical conductivity of these layers.     

Beta-decay of148,150,152Pr into levels of148,150,152Nd

Theβ ^?-decay of^148,150,152Pr into levels of^148,150,152Nd has been studied byγ-singles,γγ-coincidence and for¹⁴⁸Pr also byγγ-angular correlation measurements. The praseodymium activities have been obtained by thermal neutron-induced fission of²³⁵U followed by on-line mass separation with the helium-jet coupled mass separator HELIOS. Decay schemes for these heaviest praseodymium nuclides are proposed. From the angular correlation measurements spin values for the seven lowest levels of¹⁴⁸Nd are deduced. Spin and parity assignments for the lower levels in^150,152Nd have been extrapolated from level systematics.     

Multiple Binding Sites Contribute to the Mechanism of Mixed Agonistic and Positive Allosteric Modulators of the Cannabinoid CB1 Receptor

The cannabinoid CB1 receptor (CB1R) is an abundant metabotropic G‐protein‐coupled receptor that has been difficult to address therapeutically because of CNS side effects exerted by orthosteric drug candidates. Recent efforts have focused on developing allosteric modulators that target CB1R. Compounds from the recently discovered class of mixed agonistic and positive allosteric modulators (Ago‐PAMs) based on 2‐phenylindoles have shown promising functional and binding properties as CB1R ligands. Here, we identify binding modes of both the CP 55,940 agonist and GAT228, a 2‐phenylindole allosteric modulator, by using our metadynamics simulation protocol, and quantify their affinity and cooperativity by atomistic simulations. We demonstrate the involvement of multiple adjunct binding sites in the Ago‐PAM characteristics of the 2‐phenylindole modulators and explain their ability to compete with orthosteric agonists at higher concentrations. We validate these results experimentally by showing the contribution of multiple sites on the allosteric binding of ZCZ011, another homologous member of the class, together with the orthosteric agonist.     

Phenanthrene degradation in subcritical water

Subcritical water (<374 °C and <221 bar) has unique characteristics such as dramatically decreased dielectric constant, surface tension, and viscosity with increasing temperature, allowing for dissolution and reaction of organics in high-temperature water to occur. Additionally, the dissociation constant of water at temperatures of 200-300 °C is three orders of magnitude greater than that of ambient water, which may also contribute to the reactivity of subcritical water with certain organic compounds. In this study, the degradation and oxidation of phenanthrene in subcritical water were investigated. Both deionized water and water with 3% hydrogen peroxide were used in the degradation and oxidation studies. The effect of temperature on degradation efficiency has been determined with a temperature range of 100-350 °C. When the temperature was increased from 150 to 350 °C, the amount of phenanthrene degraded varied from 6 to 243 μg in each milliliter of deionized water. However, these quantities were increased to 195 μg at 150 °C and 3680 μg at 350 °C in each milliliter of water with 3% hydrogen peroxide. Several degradation products including phenol, benzoic acid, and ketones were identified by using gas chromatography/mass spectrometry (GC/MS).     

bryA: an unusual modular polyketide synthase gene from the uncultivated bacterial symbiont of the marine bryozoan Bugula neritina

"Candidatus Endobugula sertula," the uncultivated bacterial symbiont of Bugula neritina, is the proposed source of the bryostatin family of anticancer compounds. We cloned a large modular polyketide synthase (PKS) gene complex from "Candidatus Endobugula sertula" and characterized one gene, bryA, which we propose is responsible for the initial steps of bryostatin biosynthesis. Typical PKS domains are present. However, acyltransferase domains are lacking in bryA, and beta-ketoacyl synthase domains of bryA cluster with those of PKSs with discrete, rather than integral, acyltransferases. We propose a model for biosynthesis of the bryostatin D-lactate starter unit by the bryA loading module, utilizing atypical domains homologous to FkbH, KR, and DH. The bryA gene product is proposed to synthesize a portion of the pharmacologically active part of bryostatin and may be useful in semisynthesis of clinically useful bryostatin analogs.     

THE SENSORY PHOTORECEPTORS OF Halobacterium halobium REVISITED: ACTION SPECTRA and INFLUENCE OF BACKGROUND LIGHT*

Abstract– Action spectra of the light-dependent behavior of Halobacterium and the effect of background light have been measured with regard to the current hypothesis of Spudich and Bogomolni [Nature 312 ,509–513 (1984)], which proposes sensory rhodopsin I (sRI₅₈₇) to be the receptor for long-wavelength light, and its photoproduct S₃₇₃ to be the receptor for UV light. The action spectrum shows three maxima for attractant responses (prolonged swimming intervals) at 565, 590, and 610 nm, and two maxima for repellent responses (shortened intervals) at 370 and 480 nm. The latter is assigned to sensory rhodopsin II (P-480). All peaks are red-shifted after substitution of the endogeneous retinal by 3, 4-dehydroretinal. The peaks at 590 and 610 nm are suppressed by long-wavelength background light. Ultraviolet background light converts all attractant peaks into repellent peaks. The response at 370 nm is strongly activated by visible background light, the maximal effect occurring with 510 nm. The activated state declines with a half-life of about 1.2 s. In a growing culture, full sensitivity to UV and blue light is restored about 10 h earlier than sensitivity to long-wavelength light. Some of the results cannot easily be explained by the sRI₅₈₇/S₃₇₃ hypothesis. Explanations for the three maxima in the long-wavelength range and for the maximal activation of the UV response by 510 nm light are discussed.     

On consecutivek'th power residues

It is known that for fixedk2 and every sufficiently large primep there exists an integerr such thatr andr+1 are bothk'th power residues modulop. It has been conjectured that the least positiver with this property is bounded in terms ofk only. We prove this conjecture in the casek is a prime, and a weaker result in the general case.Dedicated to Professr E. Hlawka on the occasion of his sevetiethSupported by NSF grant MCS-8108814(A04).     

(PPh4)[(ReO2S2)CuI] und (NEt4)2[(ReOS3)Cu3Cl4]: Fixierung der bisher nicht isolierten Ionen [ReO2S2]− und [ReOS3]− durch Ausnutzung der Stabilität der CuS2(Re)- und Cu3S3(Re)-Fragmente

(PPh₄)[(ReO₂S₂)CuI] and (NEt₄)₂[ReOS₃)Cu₃Cl₄]: Fixation of the up to now not Isolated Ions [ReO₂S₂]^? and [ReOS₃]^? Utilizing the Stability of the CuS₂(Re) and Cu₃S₃(Re) Fragments (PPh₄)[(ReO₂S₂)CuI] ( 1 ) and (NEt₄)₂[ReOS₃)Cu₃Cl₄] ( 2 ) containing the up to now not isolated oxothioperrhenate ions [ReO₂S₂]^? and [ReOS₃]^? as ligands, have been prepared by the reaction of (NEt₄)[ReS₄] with PPh₃ and CuI in acetone in the presence of (PPh₄)I (( 1 )) or with CuCl in CH₂Cl₂ in the presence of (NEt₄)Cl (( 2 )), respectively. 1 and 2 have been characterized by X-ray structure analysis, elemental analysis and spectroscopic studies (IR, UV/Vis). The electronic spectra show bands which can approximately be assigned to interesting low-energy charge-transfer-transitions of the type d(Cu) → d(Re). For crystal data see Inhaltsübersicht.