bluuebunny/crossref_metadata_2025 huggingface dataset:
The Simultaneous Oxidation of Tellurium and Transition Metals by AsF5 – Syntheses and Crystal Structures of [M(SO2)6](Te6)[AsF6]6 (M = Ni, Zn) and [Cd(SO2)2][AsF6]2
Authors: Beck Johannes , Steden Folker , Zink Marcus
Published: May 2006

The reactions of elemental nickel and tellurium and of ZnTe with excess AsF5 in liquid SO2 yield [M(SO2)6](Te6)[AsF6]6 (M = Ni, Zn) as orange crystals. The crystal structure determinations (triclinic, $P{\bar 1}$, M = Ni: a = 1632.59(2), b = 1795.06(1), c = 1822.97(2) pm, α = 119.11(4), β = 90.78(4), γ = 106.28(4)°, V = 4408.24(8)·106pm3, Z = 4) show the two compounds to be isotypic. The structures are made up of discrete [M(SO2)6]2+ complexes, Te64+ clusters and octahedral [AsF6]− ions. In the [M(SO2)6]2+ complexes the metal ions are surrounded octahedrally by six SO2 molecules bound via the O atoms. The Te64+ polycations are of trigonal prismatic shape with short Te–Te bonds within the triangular faces (270 pm) and long Te–Te bonds along the edges parallel to the pseudo C3 axes of the prisms (312 pm). The arrangement of the ions is related to the Li3Bi structure type. [M(SO2)6]2+ complexes and Te64+ polycations together form a distorted cubic closest packing with all tetrahedral and octahedral interstices filled by [AsF6]− ions. The analogous reaction starting from CdTe did not yield a compound containing simultaneously [Cd(SO2)n]2+ complexes and tellurium polycations but instead Te6[AsF6]4 · 2 SO2 besides [Cd(SO2)2][AsF6]2 were obtained. It crystallizes isotypically to [Mn(SO2)2][AsF6]2 (Mews, Zemva, 2001) (orthorhombic, Fdd2, a = 1534.96(3), b = 1812.89(3), c = 892.28(3) pm, V = 2483·106 pm3, Z = 4).
The Structural Systematics of Protonation of Some Important Nitrogen‐base Ligands. I Some Univalent Anion Salts of Doubly Protonated 2, 2′:6′, 2″‐Terpyridyl
Authors: Junk Peter C. , Kepert Cameron J. , Semenova Lioubov I. , Skelton Brian W. , White Allan H.
Published: May 2006

A number of salts of 2,2′:6′,2″ ‐terpyridyl (‘tpy’) with univalent anions (halides : X = Cl, Br, I; oxyanions of increasing basicity: ClO4, NO3, ‘tfa’ = trifluoroacetate, ‘tca’ = trichloroacetate), variously solvated, have been structurally characterized by single crystal X‐ray studies. In all cases the tpy moieties are found to be doubly protonated [tpyH2]2+, the hydrogen atoms being associated with the nitrogen atoms of the peripheral rings, these together with the central nitrogen atom being directed towards a common focus, in most cases ‘chelating’ one of the counter‐ion components in diverse ways. Thus the chloride and bromide compounds are isomorphous [(tpyH2)X]+X−·H2O arrays; a second dihydrate phase is also described for the chloride, the two forms having the unchelated anion and water molecules engaged in hydrogen‐bonded networks essentially independent of [(tpyH2)X]+. The iodide is anhydrous, and of a different structural type, the anions, presumably too large for chelation, lying out of plane to either side, and linking different cations into a one‐dimensional polymer; in the perchlorate, the unsolvated aggregate is now discrete [(tpyH2)X2], a pair of perchlorate ions disposed to either side of the tpy plane, lying each with one oxygen atom interacting with both of the two protonating hydrogen atoms. In the anhydrous X = NO3, tfa, tca arrays, the lattices are solvated by the parent acids; one oxygen atom of each anion is chelated by the [tpyH2]2+ as in the chlorides, the other anion, with the acid, forming an independent ‘acid salt’ counterion [XHX]− in each case, retaining the additional protonic hydrogen rather than further protonating the central ring, all being of the form [(tpyH2)X]X·HX = [(tpyH2)X][X(HX)].
The Structural Systematics of Protonation of Some Important Nitrogen‐base Ligands. II. Some Univalent Anion Salts of Singly Protonated Bis(2‐pyridyl)amine
Authors: Junk Peter C. , Wei‐Min Lu , Semenova Lioubov I. , Skelton Brian W. , White Allan H.
Published: May 2006

Syntheses and single crystal X‐ray structure determinations are recorded for a number of normal and ‘acid’ salts of bis(2‐pyridylamine), ‘dpa’, with univalent anions, X, variously hydrated, i.e. [dpaH]X·nH2O, and [dpaH]X·HX·nH2O. The ‘normal’ salt arrays so characterized are for X = Br− (n = 2, isomorphous with the previously described chloride compound) and, I−, ClO4−, ‘tca−’ (≡ Cl3CCO2)− (all n = 1); acid salt arrays are described for X = NO3− and tca (both n = 0). In all cases except those of X = ClO4−, NO3−, there is one independent formula unit devoid of crystallographic symmetry comprising the asymmetric unit of the structure. In all cases, the proton associated with the cation is ‘chelated’ by the pair of ring nitrogen atoms, disposed ‘endo’; in the tca adducts and the nitrate salt, the total cation is disordered in each case by inversion about a real or putative inversion centre between the rings. In the perchlorate compound, the (ordered) cation lies on a crystallographic 2‐axis, as does the water molecule, and the perchlorate ion, which is disordered about such an axis; in the nitrate compound, the acid hydrogen atom is modelled as disposed on a crystallographic inversion centre between a pair of symmetry‐related nitrate groups, containing, like the Htca adduct, the [XHX]− moiety rather than a diprotonated cation.
The Iron Hydrido Complex [FeH(dppe)2]+: Solution and Solid‐State Reactivity with Dinitrogen
Authors: Franke Oliver , Wiesler Beatrix E. , Lehnert Nicolai , Peters Gerhard , Burger Peter , Tuczek Felix
Published: May 2006

The blue compound [FeH(dppe)2]BPh4 (1) (dppe = 1,2‐bis(diphenylphosphino)ethane) is investigated by optical absorption, vibrational, NMR and Mössbauer spectroscopy as well as magnetic susceptibility measurements. In the solid state, 1 is found to be paramagnetic (S=1) whereas in tetrahydrofuran (thf) solution it is diamagnetic. Importantly, 1 reacts with dinitrogen in thf solution and in the solid state to give the yellow and green dinitrogen complexes 2a and 2b, respectively, both of which have the formula [FeH(N2)(dppe)2]BPh4. Apart from their colour and optical spectroscopic properties, the dinitrogen compounds 2a and 2b also differ in their magnetic, Mössbauer and vibrational properties. The N‐N stretching frequency of 2a is found at 2120 cm−1 whereas 2b exhibits an N‐N stretching vibration of 2145 cm−1. Moreover, 2a is diamagnetic whereas 2b is paramagnetic. DFT is employed to determine the relative energies and structure of 1 and its dinitrogen adducts in the singlet and triplet state.
Structure and Properties of GdAuSn and the GdAuSn/MnAuSn System
Authors: Casper Frederick , Ksenofontov Vadim , Kandpal Hem Chandra , Reiman Sergey , Shishido Toetsu , Takahashi Masashi , Takeda Masuo , Felser Claudia
Published: May 2006

The crystal structure of GdAuSn was refined by means of single crystal X‐ray diffraction. Band structure calculations based on the structural data confirmed the antiferromagnetic ground state and the metallic behaviour of GdAuSn. 119mSn, 155Gd and 197Au Mössbauer spectroscopic studies were used to verify the values of the hyperfine parameters that were given by the band structure calculations. Band structure calculations of MnAuSn confirmed that this half‐Heusler compound belongs to the family of half‐metallic ferromagnets. Magnetic susceptibility, conductivity and Mössbauer studies were used to characterize granular material based on the half‐Heusler ferromagnet MnAuSn in the antiferromagnetic GdAuSn matrix. Magnetoresistance measurements of the granular systems revealed an enormously high positive effect at temperatures below the antiferromagnetic ordering in GdAuSn.
Chemischer Transport ternärer Oxide in den Systemen Ca/Mo/O und Sr/Mo/O
Authors: Steiner Udo , Reichelt Werner
Published: May 2006

Chemical Vapour Transport of Ternary Oxides in the Systems Ca/Mo/O and Sr/Mo/O

The chemical vapour transport behaviour of ternary phases in the Ca/Mo/O and Sr/Mo/O systems has been investigated using Cl2 as transport agent in a temperature gradient 1423 to 1323 K. MMoO4 (M= Ca, Sr) migrate in the above‐mentioned temperature gradient with rates of 0.1 to 0.2 mg/h. Starting from three phase mixtures crystals of the compounds MMo5O8 have been grown (migration rates: M = Ca 0.1 mg/h, M = Sr 0.01 mg/h). The observed transport behaviour is compared with predictions given by thermo dynamical model calculations and the influences of source composition and the moisture contents are described in detail.
High‐field (94‐GHz) EPR spectroscopy on the S2 multiline signal of photosystem II
Authors: Teutloff Christian , Keßen Sven , Kern Jan , Zouni Athina , Bittl Robert
Published: May 2006

The multiline signal of the S2 state in Photosystem II was measured both in frozen‐solution and single‐crystal preparations from the cyanobacterium Thermosynechococcus elongatus. The frozen‐solution EPR spectrum shows a gaussian‐like line shape without any resolution of Mn hyperfine couplings. This line shape can be understood on the basis of the single‐crystal spectra, where a strong orientation dependence of partially resolved hyperfine structures appears. Simulation of the frozen‐solution spectrum on the basis of Mn hyperfine couplings taken from published pulse‐ENDOR data yields a fully rhombic g‐matrix for the multiline signal with principal components 1.997, 1.970, and 1.965. The resulting isotropic g‐value g
iso
= 1.977 is surprisingly small compared to other manganese complexes containing manganese ions in the formal oxidation states three and four.
Brain pyruvate and 2‐oxoglutarate dehydrogenase complexes are mitochondrial targets of the CoA ester of the Refsum disease marker phytanic acid
Authors: Bunik Victoria I. , Raddatz Günter , Wanders Ronald J.A. , Reiser Georg
Published: May 2006

Pyruvate and 2‐oxoglutarate dehydrogenase complexes are strongly inhibited by phytanoyl‐CoA (IC50
≈ 10−6–10−7
M). Palmitoyl‐CoA is 10‐fold less potent. Phytanic or palmitic acids have no inhibitory effect up to 0.3 mM. At the substrate saturation, the acyl‐CoA's affect the first and second enzymatic components of the 2‐oxoglutarate dehydrogenase complex, while the third component is inhibited only at a low saturation with its substrate dihydrolipoamide. Thus, key regulatory branch points of mitochondrial metabolism are targets of a cellular derivative of phytanic acid. Decreased activity of the complexes might therefore contribute to neurological symptoms upon accumulation of phytanic acid in Refsum disease.
Hand Surgery on Patients Who Are “High Risk” For Blood-Borne Viruses
Authors: AL-ANI S. A. , MOHAN D. , PLATT A. J.
Published: May 2006

There is a risk of transmission of blood-borne viruses (BBV) to health-care workers when performing hand surgery on intravenous drug abusers and other patients known to have BBV. This review summarises methods and procedures that may be employed to help reduce this risk to a minimum. High-risk patients should be identified early and a non-invasive procedure considered. Only experienced staff should scrub and appropriate clothing should be worn. Sharp instrument use should be kept to a minimum and only instrument retraction and suturing should be employed. When possible, wounds should be closed with staples, glue or absorbable sutures. Appropriate steps must be taken to reduce the risk of injuries from sharp bone ends, K-wires and splash exposure during irrigation.
The early road to material requirements planning
Authors: Mabert Vincent A.
Published: May 2006

Material requirements planning (MRP) systems became a prominent approach to managing the flow of raw material and components on the factory floor in the late 20th century. Its adoption was not an over night phenomenon, but was a slow progression over many decades. This article chronicles many developments and events during the formative years of MRP, highlighting changes in computer technology and contributions by key early proponents of this approach for managing the flow of material on the factory floor.
Parathyroid Hormone: A Sensitive Predictor of Hypocalcemia Following Total Thyroidectomy
Authors: Khafif Avi , Pivoarov Arie , Medina Jesus E. , Avergel Avraham , Gil Ziv , Fliss Dan M.
Published: May 2006

OBJECTIVE

To investigate whether monitoring parathyroid hormone (PTH) could predict hypocalcemia following total thyroidectomy or other bilateral thyroid manipulations.

STUDY DESIGN AND SETTING

Forty patients undergoing total thyroidectomy as well as other bilateral thyroid procedures were prospectively enrolled. PTH levels were measured preoperatively and 30 minutes postoperatively. Calcium levels were measured preoperatively and every 8–12 hours for the first 72 postoperative hours. Changes in PTH levels as well as symptoms of hypocalcemia were correlated with postoperative hypocalcemia.

RESULTS

Hypocalcemia developed in 13/40 patients (32.5%), mainly those patients undergoing total thyroidectomy in conjunction with paratracheal neck dissections. The respective sensitivity and specificity of a drop in PTH for detecting hypocalcemia was 92% and 66% (50% drop), 23% and 75% (75% drop), and 46% and 100% (drop below normal range).

CONCLUSIONS

A 50% drop in PTH levels 30 minutes following bilateral thyroid procedures is a sensitive predictor of hypocalcemia. A drop of 75% is a highly specific indicator of postoperative hypocalcemia, though not highly sensitive.
Tracheal Reconstruction with Porcine Small Intestine Submucosa in a Rabbit Model
Authors: Gubbels Samuel P. , Richardson Mark , Trune Dennis , Bascom Daphne A. , Wax Mark K.
Published: May 2006

OBJECTIVE

To evaluate the ability of porcine small intestine submucosa (SIS) to 1) maintain airway patency, 2) integrate, 3) prevent granulation tissue formation, and 4) permit mucosalization when used for tracheal reconstruction. Further studies were performed to evaluate the ability of SIS to support neochondrogenesis and investigate the impact of neochondrogenesis on airway patency.

STUDY DESIGN

Prospective, controlled animal trial with SIS used with and without a perichondrial flap to reconstruct a tracheal defect in a rabbit model. Functional, histologic and endoscopic analyses were performed.

RESULTS

All animals except 1 control animal were without stridor. The SIS graft supported neochondrogenesis, was completely mucosalized and was well integrated into the neotrachea. There was minimal granulation tissue formation. Endoscopic analyses did not reveal a consistent, significant difference in airway patency when SIS, with or without a perichondrial flap, was used for reconstruction.

CONCLUSION

SIS can be used to reconstruct a sublethal rabbit tracheal defect with no mortality and minimal morbidity.
Does Topical Application of 5‐Fluorouracil Ointment Influence Inner Ear Function?
Authors: Iwanaga Tetsu , Tanaka Fujinobu , Tsukasaki Naoki , Terakado Mariko , Kaieda Satoru , Takasaki Kenji , Kumagami Hidetaka , Takahashi Haruo
Published: May 2006

OBJECTIVE

To investigate the effect of 5‐fluorouracil (5‐FU) ointment on the inner ear of guinea pigs.

STUDY DESIGN AND SETTING

In group A (n = 7), 5‐FU ointment was applied into the left external auditory canal. In group B (n = 10), 5‐FU ointment was applied to the left middle ear through myringotomy. In both groups, the right ear served as a control. One week later the endocochlear DC potential (EP) was measured and morphology of the cochleae was examined using scanning electron microscopy (SEM) and light microscopy.

RESULTS

In group A, there was no significant difference between the EP values of the experimental side and the control side. In group B, there was a statistically significant difference between them (P < 0.05). Morphologic findings showed no damage.

CONCLUSION

5‐FU ointment application to the external ear seems to be safe but its application to the middle ear may pose some risk of ototoxicity.
Assessment of coastal dune vulnerability to natural and anthropogenic disturbances along the Gulf of Mexico
Authors: MARTÍNEZ M. LUISA , GALLEGO-FERNÁNDEZ JUAN B. , GARCÍA-FRANCO JOSÉ G. , MOCTEZUMA CORAL , JIMÉNEZ CLAUDIA D.
Published: May 2006

Human population density is globally three times higher along the coasts than inland, and thus environmental impacts of human activities are greater in magnitude on coastal ecosystems such as beaches and dunes. Vulnerability assessment (the loss of capacity to return to the original dynamic state after system displacement) is thus necessary to evaluate the conservation status and determine the most relevant disturbance events. Twenty-six sites along 902 km of Gulf of Mexico coastline, varying in conservation status and sedimentary dynamics, were sampled. At each site a vulnerability index (VI) was calculated based on variables that described geomorphological condition, marine influence, aeolian influence, vegetation condition and human effects. Vulnerability was very variable along the coast and only 19% of the sampled locations (mostly in the central Gulf of Mexico) displayed low vulnerability. Cluster analyses of the values assigned to the checklists for each location grouped the studied sites into three, according to their VI values. Low vulnerability locations had abundant sediment supply and low human impact. Locations with medium to high VI were mostly affected by their natural geomorphological and marine features and had medium to intense human activities. Management strategies should consider the observed variability in vulnerability, the natural dynamics of these systems and the role of human activities and interests, in order to achieve adequate policies and establish well-informed priorities for integrated coastal zone management.
Bosentan for the treatment of pulmonary arterial hypertension associated with congenital cardiac disease
Authors: Kotlyar Eugene , Sy Raymond , Keogh Anne M. , Kermeen Fiona , Macdonald Peter S. , Hayward Christopher S. , McNeil Keith D. , Celermajer David S.
Published: May 2006

Aims:Bosentan is efficacious in idiopathic pulmonary arterial hypertension, and the variants associated with connective tissue disease, but not currently approved for treatment of pulmonary arterial hypertension due to Eisenmenger's syndrome. We sought to evaluate its effect in adults with Eisenmenger's syndrome.Methods:We administered bosentan on the basis of compassionate use in 23 patients with Eisenmenger's syndrome, aged 37 plus or minus 14 years. Of the patients, 17 had never received specific treatment for pulmonary arterial hypertension, five were transitioned from treprostinil, and one from beraprost to bosentan. We measured functional class, saturation of oxygen, haemoglobin levels and six-minute walk distance at baseline, one, six months and at most recent follow-up.Results:Baseline functional class was IV in three, III in fifteen, and II in five patients. At follow-up, with a mean of 15 plus or minus 10 months, 13 of the 23 patients (57%) had improved by at least one functional class, from a median baseline of III to II (p equal to 0.016), mean saturation of oxygen at rest had increased from 81% to 84% (p equal to 0.001), and levels of haemoglobin had decreased from 178 plus or minus 26 grams per litre to 167 plus or minus 19 grams per litre (p equal to 0.001). Overall, the six-minute walk distance did not change from baseline of 335 metres. The distance walked by those not previously receiving specific therapy, however, improved from 318 plus or minus 129 to 345 plus or minus 123 metres (p equal to 0.03).Conclusion:Treatment of adults with Eisenmenger's syndrome using bosentan significantly improved functional class, saturation of oxygen at rest, and decreased levels of haemoglobin. Treatment with bosentan was associated with improvement in six-minute walk distance in those not previously receiving specific therapy. In patients already in receipt of specific therapy, transition to bosentan resulted in no clinical deterioration.
Management of oral anticoagulation in a population of children with cardiac disease using a computerised system to support decision-making
Authors: Soper Juliet , Chan George T.C. , Skinner Jonathan R. , Spinetto Heather D. , Gentles Thomas L.
Published: May 2006

Objective:To assess the impact of a computerised system to support decision-making concerning the management of warfarin used in maintenance of anti-coagulation.Design:Retrospective case series study comparing manual and computerised records of prescribing.Setting:A tertiary paediatric cardiology department in a teaching hospital.Participants:The 26 children receiving warfarin to maintain anticoagulation at the time of introduction of a computerised system to support decision-making.Interventions:A rules-based computerised system to support decisions, based on existing departmental guidelines, for management of anticoagulation using warfarin was introduced to aid prescribing physicians.Main outcomes:We assessed the stability of the International Normalised Ratio, along with the number of checks made of the ratio, and the adjustments of dosage. Dosages, and recheck interval prescriptions, were compared to the guidelines established by our department.Results:We compared 274 prescriptions made manually, and 608 made using the computerised system to support decision-making, covering periods of 4, and 11, months respectively. The mean proportion of time spent by the patients within their target range for the International ratio was maintained during the period studied, at 76 percent versus 79 percent (p = 0.79). The median number of checks of the ratio made for each patient over a period of 28 days was unchanged, at 1.9 versus 2.1 (p = 0.58). There was a significant change in prescribing practices, which more closely followed the departmental guidelines.Conclusion:The introduction of a computerised system to support decision-making maintained the stability of the International ratio using warfarin, without increasing the number of checks or adjustments of dosages, in a point-of-care service for anticoagulation in children.
Reduced pulmonary function in children with the Fontan circulation affects their exercise capacity
Authors: Matthews Iren Lindbak , Fredriksen Per Morten , Bjørnstad Per G. , Thaulow Erik , Gronn Morten
Published: May 2006

Most children with functionally univentricular hearts nowadays are treated surgically by creating a total cavopulmonary connection. In the resulting Fontan circulation, the venous return and the pulmonary arterial bed are coupled in series, bypassing the heart. This gives the potential for interaction between the abnormal circulation and function of the lungs. In this study, we investigated the pattern of impairment of pulmonary function, and its relation to decreased exercise capacity.

We performed spirometry in 33 (85 percent) of 39 eligible Norwegian children, aged from 8 to 16, with a total cavopulmonary connection, along with whole body plethysmography, the carbon monoxide single breath test, and a peak treadmill exercise test. The single breath test showed a mean corrected diffusing capacity of 66.5 percent of predicted, giving a z score of minus 2.88. The mean residual volume measured by whole body plethysmography was 146.8 percent, equivalent to a z score of 2.46, whereas the mean residual volume measured by the single breath test was 102.4 percent of predicted, this being the same as a z score of 0.43. The mean peak treadmill exercise test was 70.0 percent of predicted, equivalent with a z score of minus 3.07. Mean forced vital capacity was 85.7 percent of predicted, the equivalent z score being minus 0.92. Lung function correlated with the peak treadmill exercise test.

We have shown, therefore, that children with the Fontan circulation have reduced diffusing capacity, possibly caused by the abnormal circulation through the lungs. The difference between residual volume measured by plethysmography and the single breath test implies trapping of air. The correlation of parameters for lung function with peak consumption of oxygen during exercise indicates that the abnormalities of pulmonary function may affect physical capacity.
Volcano‐earthquake interaction at Mauna Loa volcano, Hawaii
Authors: Walter Thomas R. , Amelung Falk
Published: May 2006

The activity at Mauna Loa volcano, Hawaii, is characterized by eruptive fissures that propagate into the Southwest Rift Zone (SWRZ) or into the Northeast Rift Zone (NERZ) and by large earthquakes at the basal decollement fault. In this paper we examine the historic eruption and earthquake catalogues, and we test the hypothesis that the events are interconnected in time and space. Earthquakes in the Kaoiki area occur in sequence with eruptions from the NERZ, and earthquakes in the Kona and Hilea areas occur in sequence with eruptions from the SWRZ. Using three‐dimensional numerical models, we demonstrate that elastic stress transfer can explain the observed volcano‐earthquake interaction. We examine stress changes due to typical intrusions and earthquakes. We find that intrusions change the Coulomb failure stress along the decollement fault so that NERZ intrusions encourage Kaoiki earthquakes and SWRZ intrusions encourage Kona and Hilea earthquakes. On the other hand, earthquakes decompress the magma chamber and unclamp part of the Mauna Loa rift zone, i.e., Kaoiki earthquakes encourage NERZ intrusions, whereas Kona and Hilea earthquakes encourage SWRZ intrusions. We discuss how changes of the static stress field affect the occurrence of earthquakes as well as the occurrence, location, and volume of dikes and of associated eruptions and also the lava composition and fumarolic activity.
Direct measurement of sea ice thermal conductivity: No surface reduction
Authors: Pringle D. J. , Trodahl H. J. , Haskell T. G.
Published: May 2006

We present new laboratory measurements of the thermal conductivity of small cores of landfast first‐year (FY) and multiyear (MY) sea ice from McMurdo Sound, Antarctica. The conductivity of surface (0–10 cm) and subsurface (45–55 cm) FY ice, 2.14 ± 0.11 and 2.09 ± 0.11 W m–1 K–1, respectively, and MY surface ice, 1.88 ± 0.13 W m–1 K–1, are all consistent with effective medium predictions for measured salinity, density, and temperature. In contrast with a previous result from thermistor array measurements in FY ice, the present measurements in FY ice show no conductivity reduction over the top 50 cm. We have reexamined the analysis of these previous array measurements and have identified analytical effects that rendered this analysis unreliable in the presence of high‐frequency surface temperature variations and pronounced surface warming and cooling events. We conclude that this apparent near‐surface conductivity reduction was an artefact.
Chlorophyll‐a variability off Patagonia based on SeaWiFS data
Authors: Romero Silvia I. , Piola Alberto R. , Charo Marcela , Garcia Carlos A. Eiras
Published: May 2006

Seasonal to interannual variability of satellite derived chlorophyll‐a over the Patagonia shelf and shelf break in the western South Atlantic are studied based on 7 years of ocean‐color data (1998–2004) from the Sea‐Viewing Wide Field‐of‐View Sensor (SeaWiFS). Strong chlorophyll‐a seasonal variability (>4 mg m−3) is observed compared to the open ocean (<1.5 mg m−3). North of 45°S, chlorophyll‐a blooms initiate in early austral spring (September and October), while south of 45°S blooms begin in late spring to early summer (November through January). The spring maximum (>3.5 mg m−3) extends from the midshelf to the shelf break between 37°S and 44°S and southward to 51°S along a narrow shelf break band. In summer the shelf break maximum persists from 37°S to 51°S, and two inner‐shelf blooms develop off Valdés Peninsula and along a near‐coastal band between 46°S and 52°S (>3 mg m−3). Chlorophyll‐a concentrations in the northern midshelf sharply decay in late spring, reaching lowest concentrations in summer (February and March) and a secondary maximum in early winter (June). Though all regions present substantial interannual variations, the bloom locations are stable. The shelf break maximum is located inshore of the front between the low salinity shelf waters and the cold, salty, and nutrient‐rich Malvinas Current waters. The inner shelf maxima are offshore of fronts separating well‐mixed coastal waters from the stratified midshelf. North of 41°S the midshelf bloom is also associated to a bottom trapped thermal front. Thus, all the high chlorophyll‐a regions are associated to well‐defined fronts.
Topographic controls on the surface energy balance of a high Arctic valley glacier
Authors: Arnold Neil S. , Rees W. Gareth , Hodson Andrew J. , Kohler Jack
Published: May 2006

This paper presents the results of a distributed, two‐dimensional surface energy balance model used to investigate the spatial and temporal variations in the surface energy balance of Midre Lovénbreen, a small valley glacier in northwest Spitsbergen, Svalbard, over the summer of 2000. We utilize high‐resolution airborne lidar data to derive a digital elevation model of the glacier and surrounding topography, on which a surface energy balance is computed, driven by meteorological data obtained from a meteorological station located on the glacier and a synoptic station maintained at the nearby Ny‐Ålesund research base. Given the high‐resolution topographic data, we focus particularly on whether the long duration of sunshine at high latitudes compensates for the higher solar zenith angles on the season‐long energy balance and whether shading by the surrounding topography plus glacier surface slope and aspect play an increased role in the patterns of solar radiation receipt (and hence melt) over the glacier surface. The model results are validated using a combination of mass balance data from the glacier, measured surface lowering at the glacier meteorological station, and by comparing a derived energy balance component from the model with a measured energy flux. Overall, the model performance is very good. Glacier topography is found to play a fundamental role in determining the surface energy balance; topographic shading, slope, and aspect and correction of the surface albedo for high solar zenith angles are found to play a crucial role in determining spatial patterns of surface energy balance and therefore melt.
Progressive increase in ice loss from Greenland
Authors: Thomas R. , Frederick E. , Krabill W. , Manizade S. , Martin C.
Published: May 2006

Laser altimeter measurements over Greenland show increasing thickening rates above 2000 m, reflecting increasing snowfall in a warming climate. But near‐coastal thinning rates have increased substantially since the mid 1990s, and net mass loss more than doubled from an average of 4–50 Gt yr−1 between 1993/4 and 1998/9 to 57–105 Gt yr−1 between 1998/9 and 2004. This increasing trend is very similar to findings from independent mass‐budget studies, but differs widely from ERS radar altimeter results. This may result from limitations associated with the large ERS footprint over sloping and undulating surfaces that typify fast, narrow glaciers where thinning is most pronounced.
Subunit architecture of multimeric complexes isolated directly from cells
Authors: Hernández Helena , Dziembowski Andrzej , Taverner Thomas , Séraphin Bertrand , Robinson Carol V
Published: May 2006

Recent developments in purification strategies, together with mass spectrometry (MS)‐based proteomics, have identified numerous in vivo protein complexes and suggest the existence of many others. Standard proteomics techniques are, however, unable to describe the overall stoichiometry, subunit interactions and organization of these assemblies, because many are heterogeneous, are present at relatively low cellular abundance and are frequently difficult to isolate. We combine two existing methodologies to tackle these challenges: tandem affinity purification to isolate sufficient quantities of highly pure native complexes, and MS of the intact assemblies and subcomplexes to determine their structural organization. We optimized our protocol with two protein assemblies from Saccharomyces cerevisiae (scavenger decapping and nuclear cap‐binding complexes), establishing subunit stoichiometry and identifying substoichiometric binding. We then targeted the yeast exosome, a nuclease with ten different subunits, and found that by generating subcomplexes, a three‐dimensional interaction map could be derived, demonstrating the utility of our approach for large, heterogeneous cellular complexes.
Electrosynthetically patterned conducting polymer films for investigation of neural signaling
Authors: Simon Daniel T. , Carter Sue A.
Published: May 2006

The ion-mediated conduction and versatility of device fabrication of conducting polymers provide a route to the study of neural signaling. Patterned junctions of conducting polypyrrole have been electropolymerized on commercially available microelectrode arrays, with typical dimensions 200μm between electrodes, each electrode being 30μm in diameter. Tetrabutylammonium perchlorate or sodium p-toluenesulfonate were used as electrolyte/counterion in the organic solvent. Individual polypyrrole junctions, when synthesized and connected in a three-electrode configuration, exhibit current-switching behavior analogous to neural weighting. Junctions copolymerized with thiophene exhibit current rectification and the nonlinear current-voltage behavior requisite for complex neural systems (i.e., the activation function).
Microplates-based rheometer for a single living cell
Authors: Desprat N. , Guiroy A. , Asnacios A.
Published: May 2006

We developed a new versatile micron-scale rheometer allowing us to measure the creep or the relaxation function (time analysis), as well as to determine the dynamical complex modulus (frequency analysis) of a single living cell. In this setup, a microscopic sample can be stretched or compressed uniaxially between two parallel microplates: one rigid, the other flexible. The flexible microplate is used as a nanonewton force sensor of calibrated stiffness, the force being simply proportional to the plate deflection. An original design of the microplates allows us to achieve an efficient feedback control of either strain or stress applied to the cell. Controlling the flexible plate deflection with a typical precision of less than 200nm, we are able to apply stresses ranging from a few pascals to thousands of pascals with a precision better than 2%. The control of the flexible plate deflexion is achieved by direct imaging of the plate tip on a photosensitive detector mounted on the phototube of an inverted microscope. Thus, the detection principle is suitable to all usual microscopes and very easy to set up. Beyond the creep function, already analyzed in detail in a previous work, we report here the first measurement of the relaxation function, as well as of the storage and the loss dynamic moduli [G′(f) and G″(f), f ranging from 0.02to10Hz] for an isolated living cell. Eventually, the rheometer we built is not limited to cell stretching. It should also be a powerful tool to study the rheology of micron sized samples such as microgels or vesicles, as well as to perform shear experiments.
Synthesis of Oligobipyridine Strands Bearing Nucleoside and Amino Acid Side Chains
Authors: Harding MM , Lehn JM
Published: May 2006

The synthesis is reported of derivatives of 6,6'-dimethyl-2,2'-bipyridine in which adenosine, thymidine aid tryptophan substituents are introduced at the 4,4'-positions as amide derivatives. Artificial oligonucleoside strands derived from the corresponding trisbipyridyl ligand , in which three bipyridyl ligands are separated by methyleneoxy bridges, have been prepared. The solubility of the nucleoside-substituted ligands in organic solvents is poor, but acylation of the ribose or deoxyribose units present in the ligands provides a mechanism whereby organic solubility can be improved. These ligands may be used for the preparation of metallo-exoreceptors , with the potential for recognition of biological targets such as nucleic acids. Preliminary metal ion complexation studies have been carried out.
Lewis-Base Adducts of Lead(II) Compounds. VIII. Synthetic and Structural Studies of Some Adducts of Linear Polyamines With Lead(II) Bromide
Authors: Harrowfield JM , Miyamae H , Shand TM , Skelton BW , Soudi AA , White AH
Published: May 2006

Syntheses and room-temperature single-crystal X-ray structure determinations are recorded for adducts of lead(II) bromide with some linear polyamines. Adducts with ethane-1,2-diamine ('en') and propane- 1,2-diamine (' pn ') are of 2:1 and 1:1 stoichiometry respectively. [(en)2PbBr2](∞|∞) is monoclinic, C2/c, a 13,076(4), b 7.586(2),c 13.248(4) Ǻ, β 117.88(2)°, Z = 4 f.u .; R was 0.029 for No = 1832 'observed' (I > 3σ(I)) reflections (a redetermination ). [( pn )PbBr2](∞|∞) is orthorhombic, Pbca , a 23.457(3), b 9.567(2), c 7.714(3) Ǻ, Z = 8; R 0.051 for No 1297. [(en)2PbBr2](∞|∞) is a single stranded linear polymer parallel to c; the lead atom, lying on a crystallographic twofold axis, is six-coordinate PbN4Br2, with the bromine atoms cis in the coordination sphere and lying opposed to a bidentate en ligand. The trans sites are linked into a chain by bridging en ligands . [( pn )PbBr2](∞|∞) is a more complex two-dimensional polymer; the pn is bidentate , but the lead atoms are now eight coordinate with doubly and quadruply bridging bromines linking them into the polymeric sheet. The adduct with '323tet' (4,7-diazadecane 1,10-diamine) is of a novel (323tet)2(PbBr2)3 stoichiometry , best represented (simplistically) as {[ Pb (323tet)]2[PbBr6]}(∞|∞); crystals are triclinic, Pī , a 11.892(4), b 9.306(3), c 9.016(6) Ǻ, α 60.74(4), β 86.04(4), γ 74.43(3)°, Z = 1 f.u ., with R 0.061 for No 2071. About one lead atom type, the ligand is quadridentate , lying on one face of the coordination sphere; the region opposite is occupied by four triply bridging bromine atoms from the [PbBr6] anionic units (which contain quasi-octahedral, centrosymmetric lead. with a pair of trans-bromine atoms terminal and the others bridging) linking the array into a two dimensional polymer.
Lewis-Base Adducts of Lead(II) Compounds. X. Synthetic and Structural Studies of Some 1:1 Adducts of 'tet-b' With Lead(II) (Pseudo-)Halides
Authors: Harrowfield JM , Miyamae H , Skelton BW , Soudi AA , White AH
Published: May 2006

Syntheses and room-temperature single-crystal X-ray structure determinations are recorded for 1 : 1 adducts of (7R*,14R*)-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane (' tet -b') with a variety of lead(II) salts. [( tet -b)PbCl2] is monoclinic, P 21/c, a 7.183(3), b 12.425(2), c 24.418(2) Ǻ, β 95.32(3)°, Z = 4; conventional R on |F| was 0.044 for 3188 independent, 'observed' (I > 3σ(I)) reflections. [( tet -b)PbI2] is monoclinic, P 21/c, a 19.920(5), b 7.772(5), c 15.605(6) Ǻ, β 108.39(2)°, Z = 4; R 0.051 for No 2507. [( tet -b) Pb (NCS)2] is orthorhombic, P 212121, a 36.99(1), b 8.996(5), c 6.964(3) Ǻ, Z = 4; R 0.043 for No 2100. All are discrete mononuclear [( tet -b)PbX2] entities in which the macrocyclic N4 ligand occupies one 'face' of the N4PbX2 coordination sphere, the thiocyanate ligands being N-bonded, with Pb -N-C angles of 116(2) and 118(1)°; interesting hydrogen-bonding interactions are found, columns of molecules being formed by way of hydrogen bonding between the coordinated (pseudo-)halides and the NH hydrogen atoms which project to the 'rear' face of the ligand of the next molecule, opposite the metal. In contrast to these, the bromide analogue, monoclinic, P21, a 9.342(3), b 12.720(5), c 18.845(5) Ǻ, β 103.17(2)°, Z = 4, R 0.035 for No 3593, is best formulated as [( tet -b) PbBr ] Br, one only of the bromide entities being bound to the lead, the other being fully dissociated by hydrogen bonding/ion pairing to the 'rear' side of adjacent ligands , forming hydrogen-bonded sheets rather than columns. This formulation has been extended to provide a description of an analogous mixed chloride- perchlorate 'double salt', [( tet -b) PbCl ] (ClO4).CH3OH, which is orthorhombic, P 212121, a 19.475(2), b 18.73(1), c 6.820(2) Ǻ, Z = 4, R 0.054 for No 3075. However, another double salt, modelled in refinement as Pb ( tet -b)Cl0.5(ClO4)1.5.H2O, orthorhombic Pnma , a 20.640(5), b 26.16(1), c 8.937(4) Ǻ, Z = 4 dimers , R 0.074 for No 1769, is in this case more appropriately described as [( tet -b) Pb (OClO2O)2Pb( tet -b)] (ClO4) Cl.H2O with perchlorate rather than halide coordinated, and an incipiently dimeric cation, as in the parent [( tet -b) Pb (OClO3)]2 (ClO4)2.2H2O.
The Conformation of Crystalline Di[3-(4'-methoxyphenyl)-2,2,4,4-tetramethylpentan-3-yl] Oxalate
Authors: Collins DJ , Dosen M , Fallon GD , Jacobs HA , Meijs GF , Rizzardo E
Published: May 2006

Di [3-(4'-methoxyphenyl)-2,2,4,4-tetramethylpentan-3-yl] oxalate (4a) and the analogous bis tetrahydropyranyl ether (4b) have been synthesized, and X-ray crystallography of the former shows an almost symmetrically staggered relationship of the t-butyl groups with respect to the plane of the benzene ring.
Guest Editorial: Rangelands, weeds and biodiversity
Authors: Grice A. C. , Martin T. G.
Published: May 2006

Australian rangelands are important for the diverse assemblages of native plants and animals that they support as well as for the wide variety of products and services that they provide. These assemblages are of national and international, cultural, social, ecological and economic significance. Woinarski (2001) identified several processes that are threatening the biodiversity of Australian rangelands, including grazing pressure, the proliferation of artificial watering points, vegetation clearing, predation by introduced animals and inappropriate fire regimes. His review also highlighted the importance of invasion by non-native plant species, a threatening process for ecosystems in other parts of Australia and around the world. Biological invasions pose a major risk for individual native species, communities and the ecological processes upon which they depend. The papers in this Special Issue of The Rangeland Journal consider non-native plant species in relation to the threats that they pose to the biodiversity of Australian rangelands and how those threats may be managed.
Value for money? Investment in weed management in Australian rangelands
Authors: Martin Tara G. , van Klinken Rieks D.
Published: May 2006

Increased awareness of the threat posed by non-native species to biodiversity and productivity has prompted an unprecedented commitment and investment in weed management activities throughout rangeland Australia. Since the launching of National Weeds Program in 1996 under the first phase of the Natural Heritage Trust (NHT), there has been a substantial increase in coordinated and strategic investment in weed management across the rangelands. Almost AU$25 million of Australian Government funding has been invested in projects specifically targeting Weeds of National Significance (WONS) that occur in the rangelands (14 species) and a further AU$56 million on projects conducted in the rangelands that included a weed management component. Substantial funding has also been invested by other levels of government, non-government organisations and landholders. We review this investment in relation to the level of funding, the types of weeds targeted, the range of projects undertaken and the effectiveness of these projects within Australia’s rangelands. Achievements include successful eradications, preventions, early interventions, containments, mitigation of impacts, increased awareness of weed threats and general capacity to respond to weed management issues.
Our review highlights several areas that, if addressed, will result in a substantial increase in the effectiveness of weed management efforts. These include: addressing discrepancies between states/territories in terms of funding and commitment to weed management; resolving conflicts between stakeholders in relation to the cost-benefit of non-native pasture grasses; encouraging projects that consider the broader natural resource management context of weed infestations; encouraging projects that examine weed complexes or the impacts of weeds in habitats with high biodiversity values such as riparian zones; and detecting and controlling weeds in the early stages of establishment. Finally, the collection of baseline information and alignment of reporting schedules with the longer term benefits of weed management projects will allow an assessment of the effectiveness of weed management projects and more strategic allocation of resources in the future.
Management of weeds in Australian rangelands: a basis for evaluating projects
Authors: Martin T. G. , Grice A. C.
Published: May 2006

There is presently no generally accepted way of evaluating weed related projects across Australian rangelands from the proposal through to the project completion stage, despite substantial investment in these activities. As a result, it is not possible to assess the overall effectiveness of many weed related investments. In order to better guide weed investment in the future, we propose a set of criteria on which to evaluate project objectives, methodologies, resources and achievements, whether the project is completed, underway, or in the proposal stage.
Isotopic evidence for large gaseous nitrogen losses from tropical rainforests
Authors: Houlton Benjamin Z. , Sigman Daniel M. , Hedin Lars O.
Published: May 2006

The nitrogen isotopic composition (
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N/
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N) of forested ecosystems varies systematically worldwide. In tropical forests, which are elevated in
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N relative to temperate biomes, a decrease in ecosystem
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N/
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N with increasing rainfall has been reported. This trend is seen in a set of well characterized Hawaiian rainforests, across which we have measured the
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N/
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N of inputs and hydrologic losses. We report that the two most widely purported mechanisms, an isotopic shift in N inputs or isotopic discrimination by leaching, fail to explain this climate-dependent trend in
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N/
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N. Rather, isotopic discrimination by microbial denitrification appears to be the major determinant of N isotopic variations across differences in rainfall. In the driest climates, the
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N/
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N of total dissolved outputs is higher than that of inputs, which can only be explained by a
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N-rich gas loss. In contrast, in the wettest climates, denitrification completely consumes nitrate in local soil environments, thus preventing the expression of its isotope effect at the ecosystem scale. Under these conditions, the
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N/
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N of bulk soils and stream outputs decrease to converge on the low
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N/
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N of N inputs. N isotope budgets that account for such local isotopic underexpression suggest that denitrification is responsible for a large fraction (24–53%) of total ecosystem N loss across the sampled range in rainfall.
Effect of Aging on the Structure and Function of Skeletal Muscle Microvascular Networks
Authors: BEARDEN SHAWN E.
Published: May 2006

Humans are active creatures, yet physical activity and activity tolerance decline over the life span. One prevailing theme in the literature to account for a portion of the reduced activity tolerance with aging is the observation that the capacity to augment blood flow to skeletal muscle may be impaired with advancing age. This dysfunction may be due to adaptations in the structure or function of their microvascular networks, which collectively determine blood flow resistance. The intent of this review is to present the current knowledge of structure and function of microvascular networks from skeletal muscle with special regard to how these may adapt to, or persist through, the aging process. Skeletal muscles are supplied by an intricate branching network of arterioles and venules. The consistency of findings among available studies suggests that the overall arteriolar and venular network branching topology establishes early in development and varies little, if at all, over the life span. Microvascular networks are not a series of functionally isolated segmental branches. Rather, these networks transmit and communicate vasomotor signals along their lengths and among their branches. Current evidence suggests that aging is associated with a decrement in the capacity of upstream vessels to respond to downstream vasodilation and signals transmitted cell‐to‐cell along the vascular wall.