ALBERT

Beschreibung: ABSTRACT A series of radiocarbon dates from two Epipalaeolithic sites – Kharaneh IV and Ayn Qasiyya – in the Azraq Basin of eastern Jordan provide a new perspective on the chronology and settlement patterns of this part of southwest Asia during the Late Pleistocene. We discuss the implications to our understanding of the chronology of Late Pleistocene lithic industries, particularly in regard to current hypotheses for the abandonment of eastern Jordan's ‘mega-sites’, Kharaneh IV and Jilat 6. Modelling a series of accelerator mass spectrometry dates from Kharaneh IV indicates a much shorter span of occupation for the site than previously assumed by the size and density of its deposits. Given the high density of material accumulated over a relatively short time span, we show that Kharaneh IV was an aggregation site occupied intensively by a significant number of people, providing new perspectives on the east Jordanian phenomenon of Epipalaeolithic ‘mega-sites’.

Beschreibung: Apatite incorporates variable and significant amounts of halogens (mainly F and Cl) in its crystal structure which can be used to determine the initial F and Cl concentrations of magmas. The amount of chlorine in the apatite lattice also exerts an important compositional control on the degree of fission track annealing. Chlorine measurements in apatite have conventionally required electron probe microanalysis (EPMA). Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) is increasingly used in apatite fission-track dating to determine U concentrations and also in simultaneous U-Pb dating and trace element measurements of apatite. Apatite Cl measurements by ICP-MS would remove the need for EPMA but the high (12.97 eV) first ionisation potential makes analysis challenging. Apatite Cl data were acquired using two analytical set-ups: a Resonetics M-50 193 nm ArF Excimer laser coupled to an Agilent 7700x quadrupole ICP-MS (using a 26 μm spot with an 8 Hz repetition rate) and a Photon Machines Analyte Excite 193 nm ArF Excimer laser coupled to a Thermo Scientific iCAP Qc (using a 30 μm spot with a 4 Hz repetition rate). Chlorine concentrations were determined by LA-ICP-MS (1140 analyses in total) for nineteen apatite occurrences, and there is a comprehensive EPMA Cl and F dataset for thirteen of the apatite samples. The apatite sample suite includes different compositions representative of the range likely to be encountered in natural apatites, along with extreme variants including two end-member chlorapatites. Between twenty-six and thirty-nine isotopes were determined in each apatite sample corresponding to a typical analytical protocol for integrated apatite fission track (U and Cl contents) and U-Pb dating, along with REE and trace element measurements. 35 Cl backgrounds (present mainly in the argon gas) were ~ 45–65 kcps in the first set-up and ~ 4 kcps in the second set-up. 35 Cl background-corrected signals ranged from ~ 0 cps in end-member fluorapatite to up to ~ 90 kcps in end-member chlorapatite. Use of a collision cell in both analytical set-ups decreased the low mass sensitivity by approximately an order of magnitude without improving the 35 Cl signal to background ratio. A minor Ca isotope was used as the internal standard to correct for drift in instrument sensitivity and variations in ablation volume during sessions. The 35 Cl/ 43 Ca values for each apatite (10–20 analyses each) when plotted against the EPMA Cl concentrations yield excellently constrained calibration relationships, demonstrating the suitability of the analytical protocol and that routine apatite Cl measurements by ICP-MS are achievable. This article is protected by copyright. All rights reserved.

Beschreibung: A new copper(II) phosphonatobenzenesulfonate incorporating 4,4′-bipyridine (4,4′- bipy ) as auxiliary ligand has been discovered through systematic high-throughput (HT) screening of the system Cu(NO 3 ) 2 ·3H 2 O/H 2 O 3 PC 6 H 4 SO 3 H/4,4′- bipy using different solvents. The hydrothermal synthesis of [Cu(HO 3 PC 6 H 4 SO 3 )(C 10 H 8 N 2 )]·H 2 O ( 1 ) was further optimized by screening various copper(II) salts. The crystal structure of 1 was determined by single-crystal X-ray diffraction and unveiled the presence of isolated sixfold coordinated Jahn–Teller-distorted Cu 2+ ions. The isolated CuN 2 O 4 octahedra are interconnected by phosphonate and sulfonate groups to form chains along the c- axis. The organic groups, namely phenyl rings and 4,4′- bipy molecules cross-link the chains into a three-dimensional framework. Water molecules are found in the narrow voids in the structure which are held by weak hydrogen bonds. Upon dehydration, the structure of 1 undergoes a phase transition, which was confirmed by TG measurements and temperature dependent X-ray powder diffraction. The new structure of 1-h was refined with Rietveld methods. Detailed inspection of the structure revealed the directional switching of the Jahn–Teller distortion upon de/rehydration. Weak ferro-/ferrimagnetic interactions were observed by magnetic investigations of 1 , which switch to antiferromagnetic below 3.5 K. Compounds 1 and 1-h are further characterized by thermogravimetric and elemental analysis as well as IR spectroscopy.

Beschreibung: The bifunctional metalloligand bis(carboxyethylgermanium)sesquioxide, (HOOCCH 2 CH 2 Ge) 2 O 3 , was employed in the systematic high-throughput (HT) investigation of the system Zn 2+ /(HOOCCH 2 CH 2 Ge) 2 O 3 /H 2 O/C 4 H 9 OH. Two new metal-organogermanates Zn[(OOCCH 2 CH 2 Ge) 2 O 3 ] ( 1 ) and Zn 2 (O 3 GeCH 2 CH 2 COO) ( 2 ) were discovered that show two new structural motifs for this class of compounds. Whereas in compound 1 a formal intercalation in the structure of (HOOCCH 2 CH 2 Ge) 2 O 3 is observed, 2 exhibits a new layered structure composed of CGeO 3 and ZnO 4 unit linked by μ 3 -oxygen atoms. Both connectivity modes lead to dense three-dimensional framework structures.

Beschreibung: Crystal Growth & Design DOI: 10.1021/cg2012205

Beschreibung: [1]  Diel vertical migration (DVM) of zooplankton and micronekton is widespread in the ocean and forms a fundamental component of the biological pump, but is generally overlooked in global models of the Earth System. We develop a parameterization of DVM in the ocean and integrate it with a size-structured NPZD model. We assess the model's ability to recreate ecosystem and DVM patterns at three well observed Pacific sites, ALOHA, K2 and EQPAC, and use it to estimate the impact of DVM on marine ecosystems and biogeochemical dynamics. Our model includes: (1) a representation of migration dynamics in response to food availability and light intensity, (2) a representation of the digestive and metabolic processes that decouple zooplankton feeding from excretion, egestion and respiration, and (3) a light-dependent parameterization of visual predation on zooplankton. The model captures the first order patterns in plankton biomass and productivity across the biomes, including the biomass of migrating organisms. We estimate that realistic migratory populations sustain active fluxes to the mesopelagic zone equivalent to between 15 and 40 % the particle export, and contribute up to half of the total respiration within the layers affected by migration. The localized active transport has important consequences for the cycling of oxygen, nutrients and carbon. We highlight the importance of decoupling zooplankton feeding and respiration and excretion with depth for capturing the impact of migration on the redistribution of carbon and nutrients in the upper ocean.

Beschreibung: ABSTRACT We analyzed a combination of airborne and terrestrial LiDAR, high-resolution photography, seismic, and acoustic data in order to gain insights into the initiation, dynamics, and talus deposition of a complex rock fall. A large (46 700 m 3 ) rock fall originated from near Ahwiyah Point in eastern Yosemite Valley and fell a total of 730 m to the valley floor on 28 March 2009. Analyses of remote sensing, seismic, and acoustic data were integrated to reconstruct the rock fall, which consisted of (1) the triggering of a 25 400 m 3 rock block in an area of intersecting and sometimes highly weathered joint planes, (2) the sliding and subsequent ballistic trajectory of the block from a steeply dipping ledge, (3) dislodging of additional rock from the cliff surface from beneath the rock fall source area, (4) a mid-cliff ledge impact that detached a volume of rock nearly equivalent in volume to the initial block, (5) sliding of the deteriorating rock mass down the remainder of the cliff, and (6) final impact at the base of the cliff that remobilized the existing talus downward and outward and produced an airblast that knocked down hundreds of trees. The depositional geomorphology indicates that the porosity of the fresh talus is significantly lower than that expected for typical blocky talus slopes, likely because the rock debris from this event was pulverized into smaller, more poorly sorted fragments and densified via dynamic compaction when compared to less energetic, fragmental-type rock falls. These results suggest that accumulation of individual rock-fall boulders tends to steepen talus slopes, whereas large, energetic rock falls tend to flatten them. Detachment and impact signals were recorded by seismic and acoustic instruments and highlight the potential use of this type of instrumentation for generalized rock fall monitoring, while LiDAR and photography data were able to quantify the cliff geometry, rock fall volume, source and impact locations, and geomorphological changes to the cliff and talus. Published in 2012. This article is a US Government work and is in the public domain in the USA.

Beschreibung: ABSTRACT Progressive rock-fall failures in natural rock slopes are common in many environments, but often elude detailed quantitative documentation and analysis. Here we present high-resolution photography, video, and laser scanning data that document spatial and temporal patterns of a 15-month-long sequence of at least 14 rock falls from the Rhombus Wall, a sheeted granitic cliff in Yosemite Valley, California. The rock-fall sequence began on 26 August 2009 with a small failure at the tip of an overhanging rock slab. Several hours later, a series of five rock falls totaling 736 m 3 progressed upward along a sheeting joint behind the overhanging slab. Over the next 3 weeks, audible cracking occurred on the Rhombus Wall, suggesting crack propagation, while visual monitoring revealed opening of a sheeting joint adjacent to the previous failure surface. On 14 September 2009 a 110 m 3 slab detached along this sheeting joint. Additional rock falls between 30 August and 20 November 2010, totaling 187 m 3 , radiated outward from the initial failure area along cliff (sub)parallel sheeting joints. We suggest that these progressive failures might have been related to stress redistributions accompanying propagation of sheeting joints behind the cliff face. Mechanical analyses indicate that tensile stresses should occur perpendicular to the cliff face and open sheeting joints, and that sheeting joints should propagate parallel to a cliff face from areas of stress concentrations. The analyses also account for how sheeting joints can propagate to lengths many times greater than their depths behind cliff faces. We posit that as a region of failure spreads across a cliff face, stress concentrations along its margin will spread with it, promoting further crack propagation and rock falls. Published in 2012. This article is a US Government work and is in the public domain in the USA.

Beschreibung: Biochemistry DOI: 10.1021/bi3013017

Beschreibung: [1]  Past plate motion between East and West Antarctica along the West Antarctic rift system had important regional and global implications. Although extensively studied, the kinematics of the rift during Eocene-Oligocene time still remains elusive. Based on a recent detailed aeromagnetic survey from the Adare and Northern Basins, located in the northwestern Ross Sea, we present the first well-constrained kinematic model with four rotations for Anomalies 12o, 13o, 16y, and 18o (26.5–40.13 Ma). These rotation poles form a cluster suggesting a stable sense of motion during that period of time. The poles are located close to the central part of the rift implying that the local motion varied from extension in the western Ross Sea sector (Adare Basin, Northern Basin, and Victoria Land Basin) to dextral transcurrent motion in the Ross Ice Shelf and to oblique convergence in the eastern end of the rift zone. The results confirm previous estimates of 95 km of extension in the Victoria Land Basin.