bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of oxygen‐substituted N‐alkyl 1‐deoxynojirimycin derivatives: Aza sugar α‐glucosidase inhibitors showing antiviral (HIV‐1) and immunosuppressive activity
Authors: van den Broek L.A.G.M. , Vermaas D.J. , van Boeckel C.A.A. , Rotteveel F.T.M. , Zandberg P. , van Kemenade F.J. , Miedema F. , Butters T.D. , Tan M.C.C.A. , Ploegh H.L.
Published: September 2010

The synthesis of a series of six less‐lipophilic analogues of the α‐glucosidase inhibitor N‐decyl‐1‐deoxynojirimycin (N‐decyl‐dNM, 5) is described. With the incorporation of a single oxygen atom, particularly at position seven in the N‐decyl side‐chain to give N‐(7‐oxadecyl)‐dNM (8), the therapeutic ratio (α‐glucosidase I inhibitory activity over toxicity in HepG2 cells) increases considerably. Compound 8 inhibits purified porcine liver α‐glucosidase I with an IC50 value of 0.28 μM. The position of the oxygen atom in the N‐decyl side‐chain is of importance since N‐(3‐oxadecyl)‐dNM (7) is less active than 8 and, moreover, is toxic to HepG2 cells at 3 mM. Subsequently, the synthesis of eight ester derivatives of N‐(7‐oxadecyl)‐dNM is described. All of these ester analogues are less active α‐glucosidase inhibitors than the parent compound 8 in HepG2 cells. The compounds were further analyzed for antiviral and immunomodulatory activity in vitro. It is found that the most potent α‐glucosidase I inhibitor from this study N‐(7‐oxadecyl)‐dNM (8) inhibits HIV‐1‐induced syncytia formation and lymphocyte proliferation in vitro. Finally, compound 8 was investigated in vivo. N‐(7‐Oxadecyl)‐dNM (8) reduced adjuvant‐induced arthritis in rats making this compound a potential candidate for treating autoimmune diseases like rheumatoid arthritis.
Sonochemistry: Theory and applications
Authors: Pestman Jolanda M. , Engberts Jan B. F. N. , de Jong Feike
Published: September 2010

Ultrasound can be used in chemistry to increase both reaction rates and yields of products. Most effects of ultrasound on chemical reactions are due to cavitation: the formation and collapse of small bubbles in the solvent. In this review, we first outline the physical background of cavitation, and discuss its dependence on factors such as sound intensity and frequency, solvent and temperature. The impact of ultrasound on chemical reactions is considered for homogeneous reactions and for heterogeneous liquid‐solid systems. The first area is mainly illustrated by a discussion of the effect of ultrasound on polymerization and depolymerization reactions, the second by selected examples in organic synthesis. The tendency of ultrasound to change reaction mechanisms in favour of homolytic (instead of heterolytic) pathways, is also briefly discussed. The specific preference for a particular pathway under sonochemical conditions, different from that under mechanical stirring has been termed “sonochemical switching”. Ultrasonic equipment for lab‐scale experiments are compared, and some practical “tricks and traps” are given.
On the stability of S‐(alkylsulfanyl) cysteine derivatives during solid‐phase synthesis
Authors: Rietman B. H. , Peters R. F. R. , Tesser G. I.
Published: September 2010

N‐Acetyl‐S‐(alkylsulfanyl)cysteine benzyl esters were synthesized as models for N‐acylated S‐(alkylsulfanyl)cysteine residues linked via an ester bond to a solid phase. The S‐protections involved were: the ethylsulfanyl, the well‐established tert‐butylsulfanyl and the newly developed tritylsulfanyl group. We investigated the chemical behaviour of the disulfides in reagents commonly applied in solid‐phase peptide synthesis using the Fmoc strategy (Fmoc SPPS). It was found that the tritylsulfanyl group as a thiol protection is comparable with the tert‐butylsulfanyl group in these respects. It is stable in trifluoroacetic acid and is rapidly reduced by thiols and phosphines. For all three cysteine esters rapid racemization was observed in piperidine (25%) in DMF, the amides being chirally stable. The demonstrated chiral instability of cysteine esters has consequences for the solid‐phase synthesis of peptides using the Fmoc protocol.
Coulomb‐induced intramolecular exciplex formation in semiflexible donor‐bridge‐acceptor compounds in nonpolar solvents as a function of temperature
Authors: Wegewijs B. , Ng A. K. F. , Verhoeven J. W.
Published: September 2010

The mechanism of exciplex formation of two donor‐bridge–acceptor compounds, both containing a strong donor ‐ acceptor pair interconnected by a piperidine ring, was studied in nonpolar solvents as a function of temperature. Fluorescence spectra at low temperature in methylcyclohexane show that in both compounds the exciplex is formed via the harpooning mechanism, i.e. long‐range charge separation leading to an extended charge‐transfer state, followed by Coulomb‐induced folding to the exciplex state. The kinetic link between these two emissive states could be established by studying their transient fluorescence curves. Furthermore, the activation energy of the folding process was estimated from the decay rates of the extended charge‐transfer state in various solvents. An interpretation of the observed activation energies in terms of Kramers theory is presented, which gives an indication of the relative importance of internal steric effects and solvent viscosity on the dynamics of the folding process.
Formation of the 1,3‐Oxazepine ring system during the oxidation of an alcohol with activated dimethyl sulfoxide
Authors: Belle David Din , Tolvanen Arto , Lounasmaa Mauri
Published: September 2010

Alcohol 3, an intermediate in indole alkaloid synthesis, was converted to the ox‐azepinoindoloquinolizine 5 by oxidation with DMSO activated by the sulfur trioxide/pyridine complex. The ring closure proceeds through the common oxidation side‐product, methylthiomethyl ether 4.
The Cossee mechanism: Migratory insertion reactions in palladium phosphine‐phosphinite complexes
Authors: van Leeuwen Piet W. N. M. , Roobeek Kees F.
Published: September 2010

Methylpalladium complexes containing phosphine‐phosphinite bidentate ligands 1‐3 undergo stepwise insertions of carbon monoxide and norbornadiene. The 31P NMR spectra prove that a true migration pathway is the mechanism for this reaction.
2‐(Trifluoromethyl)piperazine: Synthesis and characterization using NMR and X‐ray photoelectron spectroscopy
Authors: Jenneskens Leonardus W. , Mahy Jan , de Brabander‐van den Berg Ellen M. M. , van der Hoef Ineke , Lugtenburg Johan
Published: September 2010

The synthesis of 2‐(trifluoromethyl)piperazine (1) is reported. 1H NMR spectroscopy shows that in the chair‐type piperazine ring the CF3 group occupies an equatorial position. X‐ray photoelectron spectroscopy of solid 1 reveals that the CF3 group induces a secondary (β) chemical shift of 1.5 eV on the C 1s core binding energy of its nearest neighbour carbon atom. The results are supported by semi‐empirical PM3 and HAM/3 calculations.
Dispiroketals in synthesis (Part 16): Functionalised dispiroketals as new chiral auxiliaries; the synthesis of dihydroxylated dispiroketals in optically pure form and their application as bifunctional, C2‐symmetrical, chiral auxiliaries for highly stereoselective Michael additions
Authors: Bezuidenhoudt Barend C. B. , Castle Grant H. , Innes Jean E. , Ley Steven V.
Published: September 2010

A range of rigid, architecturally complex diols derived from dispiroketals have been synthesised. A bifunctional, C2‐symmetrical, chiral auxiliary derived from these dihydroxylated dispiroketals has been used to induce a high degree of asymmetry in Michael additions of cuprates to a variety of di‐α, β‐unsaturated ester systems.
Synthesis of enantiomerically pure tricarbonylchromium(0) complexes of ortho substituted styrenes from (S)‐α‐Methylbenzylamine
Authors: Christian Paul W. N. , Gibson Susan E. , Gil Richard , Jones P. Caroline V. , Marcos Carlos F. , Prechtl Frank , Wierzchleyski Adam T.
Published: September 2010

Tricarbonylchromium(0) complexes of sulfur, phosphorus, silicon, iodine, tin and carbon substituted (S)‐(α‐methylbenzyl)dimethylamines are oxidized by dimethyldioxirane to enantiomerically pure tricarbonylchromium(0) complexes of substituted styrenes; the reactions proceed via a chemoselective oxidation of the tertiary amines to their N‐oxides, one of which was isolated, and a subsequent Cope reaction.
Synthesis of chiral (phosphinoaryl)oxazolines, a versatile class of ligands for asymmetric catalysis
Authors: Koch Guido , Lloyd‐Jones Guy C. , Loiseleur Olivier , Pfaltz Andreas , Prétôt Roger , Schaffner Silvia , Schnider Patrick , von Matt Peter
Published: September 2010

Enantiomerically pure 2‐[2‐(diphenylphosphino)aryl]oxazolines are readily prepared from 2‐bromobenzonitrile by transmetalation with BuLi, subsequent reaction with chloro‐diphenylphosphine and conversion of the resulting phosphinoaryl nitrile to the oxazoline by treatment with a chiral amino alcohol in the presence of ZnCl2. An alternative synthesis is based on the orthometalation of 2‐aryloxazolines followed by reaction with chlorodiphenylphosphine.
Synthesis of dipeptides containing α‐substituted amino acids; their use as chiral ligands in Lewis‐acid‐catalyzed reactions
Authors: Kaptein Bernard , Monaco Vania , Broxterman Quirinus B. , Schoemaker Hans E. , Kamphuis Johan
Published: September 2010

L‐α‐Methylphenylalanine, obtained by enzymatic resolution of the corresponding racemic amide with amidase from Ochrobactrum anthropi NCIMB 40321, was used in the synthesis of dipeptides containing α‐substituted amino acids. The 2‐hydroxynaphthalene‐1‐carboxaldehyde Schiff bases of the dipeptides (1 and 2) were tested as Ti(IV) and Al(III) complexes in asymmetric Lewis‐acid‐catalyzed reactions. Only the Al(III) complex of 2 showed moderate enantioselectivity in the cyanation reaction of benzaldehyde with TMS‐CN.
Alkali‐cation transport through supported liquid membranes mediated by solvent‐linked carriers
Authors: Visser Herman C. , Vink Remco , Snellink‐Ruel Bianca H. M. , Kokhuis Simone B. M. , Harkema Sybolt , de Jong Feike , Reinhoudt David N.
Published: September 2010

Neutral macrocyclic alkali‐cation receptors have been covalently linked to one or more molecules of the membrane solvent 2‐nitrophenyl n‐octyl ether (NPOE). These compounds are all highly lipophilic and soluble in NPOE. The flux of alkali‐perchlorate salts through supported liquid membranes (SLMs) has been optimized by variation of the carrier content in the membrane and the temperature. With all carriers, the optimum flux is reached at carrier contents of about 20% (w/w) in NPOE. Above this carrier content the flux decreases because of an increase in the viscosity of the membrane solutions. Relatively low activation energies for transport indicate that the transport is diffusion‐limited. The excellent compatibility between the carriers and the membrane solvent leads to very stable membranes (NPOE/Accurel®). The mechanism of alkali perchlorate transport has been investigated by variation of the source‐phase salt activity and the carrier concentration. Indications about ion pair formation and 2/1 carrier/cation complexation have been obtained from variation of the carrier concentration and transport selectivity measurements.
Hydrocarbons and chloroaromatics from anilines and n‐butyl nitrite
Authors: Giumanini Angelo G. , Verardo Giancarlo , Gorassini Fausto , Strazzolini Paolo
Published: September 2010

A single reagent, i.e. n‐butyl nitrite, can be used to oxidize an aromatic amine, or the corresponding N‐methylene derivative, to a diazo compound followed by its subsequent reduction to hydrocarbon in a single batch. Alternatively, a chloro derivative can be obtained if carbon tetrachloride is used as the solvent. The reactions appear to be general and complete product identification was accomplished.
Synthesis of a potential enzyme‐specific inhibitor of squalene synthase
Authors: Valentijn A. R. P. M. , de Haan R. , Hagens S. , de Kant E. , van der Marel G. A. , Cohen L. H. , van Boom J. H.
Published: September 2010

A multi‐step synthesis of phosphinylphosphonate analogue 12 of the proposed farnesyl‐farnesyl‐enzyme (FFE) intermediate in the enzymatic conversion of farnesyl pyrophosphate to squalene is described. In addition, evidence is presented of the inhibitory effect of 12 on squalene synthase.
Synthesis and crystal structure of [Bu4N][Ni(mdt)2], a novel nickel dithiolene complex (H2mdt = 2H‐1,3‐dithiole‐4,5‐dithiol)
Authors: Veldhuizen Yvonne S. J. , Veldman Nora , Spek Anthony L. , Haasnoot Jaap G. , Reedijk Jan
Published: September 2010

[Bu4N][Ni(mdt)2] (H2mdt = 2H‐1,3‐dithiole‐4,5‐dithiol) has been prepared in a three‐step synthesis from [Bu4N]2[Zn(dmit)2] (H2dmit = 2‐thione‐1,3‐dithiole‐4,5‐dithiol). The crystal structure is reported which shows that the Ni(mdt)2 anion is distorted significantly from planarity.
A family firm variant of the behavioral agency theory
Authors: Lim Elizabeth N. K. , Lubatkin Michael H. , Wiseman Robert M.
Published: September 2010

There is currently a debate in the literature regarding whether family firm ownership fosters or discourages risk‐taking activities. In this article, we propose a contingency framework that shifts the focus of investigation: instead of asking whether family firms tend to be risk takers, we suggest specific ownership conditions under which privately owned family‐managed firms are more likely to engage in risk taking. We do so by integrating concepts from the behavioral agency model and a resource‐based concept known as familiness to advance a base proposition that explains the effects of different ownership structures (controlling ownership, sibling partnership, and cousin consortium) on risk‐taking behaviors in family firms. Then, drawing insights from the family firm and household economics literatures, we discuss the contingent effects of three distinct forms of altruism (parental, paternalistic, and psychosocial) on the base proposition. The framework advances our current understanding of risk taking in family businesses in two ways: first, by proposing how and when risk‐taking behaviors differ across these firms; and second, by offering a variant of the base behavioral agency model that is better suited for explaining risk taking at family firms. Copyright © 2010 Strategic Management Society.
A modeling framework for the analysis of HPV incidence and persistence: A semi‐parametric approach for clustered binary longitudinal data analysis
Authors: Kong Xiangrong , Gray Ronald H. , Moulton Lawrence H. , Wawer Maria , Wang Mei‐Cheng
Published: September 2010

Human papillomavirus (HPV) infection is a common sexually transmitted disease of growing public health importance, and over 40 genotypes have been identified in genital infections. Current HPV cohort studies often follow participants at pre‐determined visits, such as every 6 months, and data generated from such epidemiology studies can be described as clustered longitudinal binary data where correlation arises in two ways: the directionless clustering due to the multiple genotypes tested within an individual, and the temporal correlation among the repeated measurements on the same genotype along time. Current analyses for identification of risk factors associated with HPV incidence and persistence often either do not fully utilize information in the data set or ignore the correlation between the multiple genotypes. Given the scientific definition of incidence and persistence, conditional probability modeling provides us a natural mathematical tool. We thus present a semi‐parametric regression model for such data where full specification of the joint multivariate binary distribution is avoided by using conditioning argument to handle the temporal correlation and GEE to account for the correlation between the multiple genotypes. The model is applied to the HPV data from the Rakai male circumcision (MC) trial to evaluate the as‐treated efficacy of MC and also identify modifiable risk factors for incidence and persistence of oncogenic HPV types in men. A simulation study is performed to provide empirical information on the number of individuals that is needed for satisfactory power and estimation accuracy of the association parameter estimates in future studies. Copyright © 2010 John Wiley & Sons, Ltd.
Geometrische Ersatzimperfektionen für das Biegedrillknicken von Trägern aus Walzprofilen – Grundsätzliches
Authors: Kindmann Rolf , Beier‐Tertel Judith
Published: September 2010

Der Nachweis ausreichender Tragfähigkeit kann bei biegedrillknickgefährdeten Trägern mit dem Ersatzimperfektionsverfahren geführt werden. Das Verfahren wird ausführlich erläutert, und es werden Unterschiede zu genauen Berechnungsmethoden aufgezeigt. Da bei dem Verfahren geometrische Ersatzimperfektionen v0 angesetzt werden müssen, werden für ausgewählte Basissysteme genaue Werte v0 in Abhängigkeit von der Stabilitätsgefahr und der Querschnittsform ermittelt. Untersuchungen zum Einfluss auf die Tragfähigkeit führen zu dem Ergebnis, dass mit v0 = L/150 für mittlere bezogene Schlankheitsgrade realitätsnahe Bemessungsergebnisse erzielt werden. Für große bezogene Schlankheitsgrade reichen kleinere geometrische Ersatzimperfektionen aus. Vergleichsrechnungen mit den Werten nach DIN 18800‐2 und DIN EN 1993‐1‐1 (EC 3) zeigen, dass die Normenwerte zu klein sind, so dass die Tragfähigkeiten bereichsweise deutlich auf der unsicheren Seite liegen.

Equivalent geometric imperfections for the lateral torsional buckling of rolled profile beams – Fundamentals. The sufficient bearing capacity of beams susceptible to lateral torsional buckling can be verified using the equivalent imperfections method. The method is explained in detail and differences to exact calculation procedures are shown. Since equivalent geometric imperfections v0 have to be applied for this method, exact values v0 are determined for selected basis systems depending on the danger to the stability and the cross sectional shape. Analyses of the effect on the bearing capacity lead to the result that with v0 = L/150 realistic design results can be achieved for medium non‐dimensional slenderness ratios. For large non‐dimensional slenderness ratios smaller equivalent geometric imperfections are sufficient. Comparative calculations with the values according to DIN 18800‐2 and DIN EN 1993‐1‐1 (EC 3) show that the standard values are too small, as a consequence, the bearing capacities are in certain areas clearly on the unsafe side.
Design of support structures for offshore wind turbines – Interfaces between project owner, turbine manufacturer, authorities and designer
Authors: Seidel Marc
Published: September 2010

Design of support structures for offshore wind turbines is a challenging subject both technically and logistically. Many stakeholders are involved in this process, which have many technical and commercial interfaces. Managing these interfaces can involve special technical approaches and procedures, some of which are discussed in this paper. It is of great benefit to the project, if these interfaces are managed well.

Entwurf von Tragstrukturen für Offshore‐WEA – Schnittstellen zwischen Projekteignern, WEA‐Herstellern, Behörden und Tragwerksplanern. Der Entwurf von Tragstrukturen für Offshore‐Windenergieanlagen ist in technischer und logistischer Hinsicht eine anspruchsvolle Aufgabe. In diesem Prozess gibt es viele Beteiligte, die zahllose Schnittstellen technischer und kommerzieller Art haben. Zur effizienten Behandlung dieser Schnittstellen sind z. T. spezielle technische Vorgehensweisen hilfreich, die in dieser Veröffentlichung dargestellt werden. Der Erfolg eines Projektes insgesamt hängt maßgeblich von der erfolgreichen Abwicklung der Schnittstellen ab.
Next‐generation imaging development for nanoparticle biodistribution measurements
Authors: Tandon Pushpa , Nordstrom Robert J.
Published: September 2010

As nanotechnologies move closer to use in humans, quantitative imaging methods will play a vital role in answering questions of biodistribution. Accurate knowledge of the location and quantity of in vivo nanoconstructs and carriers is a challenging task, and new methods of quantitative imaging at appropriate resolutions are being developed and tested. Sustaining simultaneous advancement in both imaging development and nanotechnology research requires multidisciplinary research teams conducting experiments with interconnected goals. On an even greater scale, networks of multidisciplinary teams focused on similar issues of imaging and probe development offer opportunities for leveraging resources, as well as providing a forum for sharing ideas and creating consensus on solutions to common challenges. The Network for Translational Research (NTR): Optical Imaging in Multimodal Platforms from the National Cancer Institute is just such a network. Four multidisciplinary centers are accepting the challenges of developing and optimizing multimodal imaging hardware and software along with imaging probe development. These efforts are similar to the efforts that will be required for future studies of in vivo nanoparticle biodistribution. In addition to technology development and optimization, the network is organized to confront the challenges of validation of the imaging hardware and associated imaging agents, similar to the methods needed for validating nanomedicine. WIREs Nanomed Nanobiotechnol 2011 3 5–10 DOI: 10.1002/wnan.117

This article is categorized under:

Therapeutic Approaches and Drug Discovery > Emerging Technologies

Diagnostic Tools > In Vivo Nanodiagnostics and Imaging

Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease
Loop Ileostomy Closure: Comparison of Cost Effectiveness between Suture and Stapler
Authors: Horisberger Karoline , Beldi Guido , Candinas Daniel
Published: September 2010

Background

Closure of loop ileostomy can be safely performed using sutures or staplers. The aim of the present study was to compare the cost effectiveness of three different techniques.

Methods

A total of 128 consecutive patients who underwent closure of loop ileostomy between January 2002 and December 2008 were analyzed retrospectively. The primary outcome parameter was operative cost.

Results

Closure of ileostomy was performed in 66 patients with hand‐sewn anastomosis, in 25 patients with stapler only, and in 37 patients with a combination of stapler and suture. There were no differences in terms of early and late postoperative complications. Operative time was significantly longer for “suture only” (101.4 ± 26 min) than for “stapler/suture” (−4.9 min) and “stapler only” (−17.8 min); the difference between the three groups is significant (p = 0.05). Duration of hospital stay was not different among the three groups. Operative costs with “stapler/suture” (1,755.9 ± 355.6 EUR) were significantly higher than with “suture only” (−254 EUR; p = 0.001) and “stapler only” (−236 EUR; p = 0.005).

Conclusions

Operative time using the stapler only is significantly shorter than with hand‐sewn anastomosis or combinations of stapler and suture. Operative costs are significantly higher for a procedure that includes suture and stapler.
Real Exchange Rates and Competitiveness: The Political Economy of Skill Formation, Wage Compression, and Electoral Systems
Authors: IVERSEN TORBEN , SOSKICE DAVID
Published: September 2010

A major puzzle in the open economy literature is why some countries have persistently higher real exchange rates than others. Even more puzzling is the fact that countries with high real exchange rates are strong export performers. We solve both puzzles with a model that integrates two central debates in the comparative political economy of advanced economies: one linking wage bargaining, incomes policy, and competitiveness, and the other linking partisanship, political institutions, and redistribution. We bring the two together by emphasizing the role of skill formation. We argue that union centralization is necessary for wage restraint and training on a large scale, but this in turn requires a political coalition that subsidizes such training. When both are present, wage restraint generates external competitiveness, whereas wage compression pushes up sheltered prices and hence the real exchange rate, and vice versa. We test the argument on data on export performance and real exchange rates.
CENTRES OF SYMMETRIC CELLULAR ALGEBRAS
Authors: LI YANBO
Published: September 2010

LetRbe an integral domain andAa symmetric cellular algebra overRwith a cellular basis {CλS,T∣λ∈Λ,S,T∈M(λ)}. We construct an idealL(A) of the centre ofAand prove thatL(A) contains the so-called Higman ideal. WhenRis a field, we prove that the dimension ofL(A) is not less than the number of nonisomorphic simpleA-modules.
CONVEX STANDARD FUNDAMENTAL DOMAIN FOR SUBGROUPS OF HECKE GROUPS
Authors: IBRAHIMOU BOUBAKARI , YAYENIE OMER
Published: September 2010

It is well known that if a convex hyperbolic polygon is constructed as a fundamental domain for a subgroup of SL(2,ℝ), then its translates by the group form a locally finite tessellation and its side-pairing transformations form a system of generators for the group. Such a hyperbolically convex fundamental domain for any discrete subgroup can be obtained by using Dirichlet’s and Ford’s polygon constructions. However, these two results are not well adapted for the actual construction of a hyperbolically convex fundamental domain due to their nature of construction. A third, and most important and practical, method of obtaining a fundamental domain is through the use of a right coset decomposition as described below. If Γ2 is a subgroup of Γ1 such that Γ1=Γ2⋅{L1,L2,…,Lm} and 𝔽 is the closure of a fundamental domain of the bigger group Γ1, then the set is a fundamental domain of Γ2. One can ask at this juncture, is it possible to choose the right coset suitably so that the set ℛ is a convex hyperbolic polygon? We will answer this question affirmatively for Hecke modular groups.
Cambrian rocks and faunas of the Wachi La, Black Mountains, Bhutan
Authors: HUGHES NIGEL C. , MYROW PAUL M. , MCKENZIE N. RYAN , HARPER D. A. T. , BHARGAVA O. N. , TANGRI S. K. , GHALLEY K. S. , FANNING C. M.
Published: September 2010

The Pele La Group in the Wachi La section in the Black Mountains of central Bhutan represents the easternmost exposure of Cambrian strata known in the Himalaya. The group contains a succession of siliciclastic rocks with minor amounts of carbonate, the uppermost unit of which, the Quartzite Formation, bears age-diagnostic trilobite body fossils that are approximately 493 Ma old. Trilobite species includeKaolishania granulosa, Taipaikia glabraand the new speciesLingyuanaspis sangae.A billingsellid brachiopod,Billingsellacf.tonkiniana, is co-occurrent. This fauna is precisely correlated with that of a specific stratigraphic horizon within the upper part of theKaolishaniaZone, Stage 9 of the Cambrian System, Furongian Epoch of the North China block, and thus represents the youngest Cambrian sedimentary rocks yet known from the Himalaya. The faunal similarity suggests proximity between North China and the Himalayan margin at this time. This unit was deposited in a predominantly storm-influenced shelf and shoreface environment. U–Pb geochronological data from detrital zircon grains from the fossil-bearing beds of the Quartzite Formation and strata of the underlying Deshichiling Formation show grain age spectra consistent with those from Cambrian rocks of the Lesser and Tethyan Himalaya in Tibet, India and Pakistan. These data support continuity of the northern Gondwanan margin across the Himalaya. Prominent peaks of approximately 500 Ma zircons in both the Quartzite and Deshichiling formations are consistent with the Furongian (late Cambrian) age assignment for these strata. The presence of these relatively young zircon populations implies rapid post-cooling erosion of igneous bodies and subsequent deposition which may reflect the influence of a widespread Cambro-Ordovician orogenic event evident in the western Himalaya.
Numerical simulations of Rayleigh–Bénard convection for Prandtl numbers between 10−1 and 104 and Rayleigh numbers between 105 and 109
Authors: SILANO G. , SREENIVASAN K. R. , VERZICCO R.
Published: September 2010

We summarize the results of an extensive campaign of direct numerical simulations of Rayleigh–Bénard convection at moderate and high Prandtl numbers (10−1 ≤ Pr ≤ 104) and moderate Rayleigh numbers (105 ≤ Ra ≤ 109). The computational domain is a cylindrical cell of aspect ratio Γ = 1/2, with the no-slip condition imposed on all boundaries. By scaling the numerical results, we find that the free-fall velocity should be multiplied by $1/\sqrt{{\it Pr}}$ in order to obtain a more appropriate representation of the large-scale velocity at high Pr. We investigate the Nusselt and the Reynolds number dependences on Ra and Pr, comparing the outcome with previous numerical and experimental results. Depending on Pr, we obtain different power laws of the Nusselt number with respect to Ra, ranging from Ra2/7 for Pr = 1 up to Ra0.31 for Pr = 103. The Nusselt number is independent of Pr. The Reynolds number scales as ${\it Re}\,{\sim}\,\sqrt{{\it Ra}}/{\it Pr}$, neglecting logarithmic corrections. We analyse the global and local features of viscous and thermal boundary layers and their scaling behaviours with respect to Ra and Pr, and with respect to the Reynolds and Péclet numbers. We find that the flow approaches a saturation state when Reynolds number decreases below the critical value, Res ≃ 40. The thermal-boundary-layer thickness increases slightly (instead of decreasing) when the Péclet number increases, because of the moderating influence of the viscous boundary layer. The simulated ranges of Ra and Pr contain steady, periodic and turbulent solutions. A rough estimate of the transition from the steady to the unsteady state is obtained by monitoring the time evolution of the system until it reaches stationary solutions. We find multiple solutions as long-term phenomena at Ra = 108 and Pr = 103, which, however, do not result in significantly different Nusselt numbers. One of these multiple solutions, even if stable over a long time interval, shows a break in the mid-plane symmetry of the temperature profile. We analyse the flow structures through the transitional phases by direct visualizations of the temperature and velocity fields. A wide variety of large-scale circulation and plume structures has been found. The single-roll circulation is characteristic only of the steady and periodic solutions. For other regimes at lower Pr, the mean flow generally consists of two opposite toroidal structures; at higher Pr, the flow is organized in the form of multi-jet structures, extending mostly in the vertical direction. At high Pr, plumes mainly detach from sheet-like structures. The signatures of different large-scale structures are generally well reflected in the data trends with respect to Ra, less in those with respect to Pr.
Studies on ultrasmall bacteria in relation to the presence of bacteria in the stratosphere
Authors: Alshammari Fawaz , Wainwright Milton , Alabri Khalid , Alharbi Sulamain A.
Published: September 2010

Recent studies confirm that bacteria exist in the stratosphere. It is generally assumed that these bacteria are exiting from Earth, although it is possible that some are incoming from space. Most stratospheric bacterial isolates belong to the spore-forming genusBacillus, although non-spore formers have also been isolated. Theoretically, the smaller a bacterium is, the more likely it is to be carried from Earth to the stratosphere. Ultrasmall bacteria have been frequently isolated from Earth environments, but not yet from the stratosphere. This is an anomalous situation, since we would expect such small bacteria to be over represented in the stratosphere-microflora. Here, we show that ultrasmall bacteria are present in the environment on Earth (i.e. in seawater and rainwater) and discuss the paradox of why they have not been isolated from the stratosphere.
POLYNOMIAL RING CALCULUS FOR MODAL LOGICS: A NEW SEMANTICS AND PROOF METHOD FOR MODALITIES
Authors: AGUDELO JUAN C. , CARNIELLI WALTER
Published: September 2010

A new (sound and complete) proof style adequate for modal logics is defined from the polynomial ring calculus (PRC). The new semantics not only expresses truth conditions of modal formulas by means of polynomials, but also permits to perform deductions through polynomial handling. This paper also investigates relationships among the PRC here defined, the algebraic semantics for modal logics, equational logics, the Dijkstra–Scholten equational-proof style, and rewriting systems. The method proposed is throughly exemplified for S5, and can be easily extended to other modal logics.
A model for the formation of lava tubes by the growth of the crust from the levees
Authors: Valerio A. , Tallarico A. , Dragoni M.
Published: September 2010

We propose a model to explain lava tube formation by the growth of crust slabs from the levees of a channel toward its center, involving solid surface fragments. The flow dynamics are described with the steady state solution of the Navier‐Stokes equation in a rectangular channel, for a Newtonian, homogeneous, isotropic and incompressible fluid. The cooling of a lava flow is described by the mechanism of heat conduction into the atmosphere. The presence of levees is taken into account both in the dynamical and in the thermal model. As long as the flow cools, a solid layer forms at the surface, much thicker near the levees than at the center of the channel. The crust that has formed breaks under the effects of the applied stresses. Solid blocks slow the fluid down, the shear stress at the interface between crust and fluid lava increases and the flow thickens. Using the thin elastic plate approximation, we determine conditions allowing a crust to resist both the action of the shear stress due to the drag of the underlying fluid and the tensile stress due to the weight of the crust itself, detecting the required crust thickness and distances from the eruptive vent where the tube can form.
Observations and modeling of ice cloud shortwave spectral albedo during the Tropical Composition, Cloud and Climate Coupling Experiment (TC4)
Authors: Kindel Bruce C. , Schmidt K. Sebastian , Pilewskie Peter , Baum Bryan A. , Yang Ping , Platnick Steven
Published: September 2010

Ice cloud optical thickness and effective radius have been retrieved from hyperspectral irradiance and discrete spectral radiance measurements for four ice cloud cases during the Tropical Composition, Cloud and Climate Coupling Experiment (TC4) over a range of solar zenith angle (23°–53°) and high (46–90) and low (5–15) optical thicknesses. The retrieved optical thickness and effective radius using measurements at only two wavelengths from the Solar Spectral Flux Radiometer (SSFR) irradiance and the Moderate Resolution Imaging Spectroradiometer Airborne Simulator (MAS) were input to a radiative transfer model using two libraries of ice crystal single‐scattering optical properties to reproduce spectral albedo over the spectral range from 400 to 2130 nm. The two commonly used ice single‐scattering models were evaluated by examining the residuals between observed spectral and predicted spectral albedo. The SSFR and MAS retrieved optical thickness and effective radius were found to be in close agreement for the low to moderately optically thick clouds with a mean difference of 3.42 in optical thickness (SSFR lower relative to MAS) and 3.79 μm in effective radius (MAS smaller relative to SSFR). The higher optical thickness case exhibited a larger difference in optical thickness (40.5) but nearly identical results for effective radius. The single‐scattering libraries were capable of reproducing the spectral albedo in most cases examined to better than 0.05 for all wavelengths. Systematic differences between the model and measurements increased with increasing optical thickness and approached 0.10 between 400 and 600 nm and selected wavelengths between 1200 and 1300 nm. Differences between radiance and irradiance based retrievals of optical thickness and effective radius error sources in the modeling of ice single‐scattering properties are examined.
A 10 year climatology of Arctic cloud fraction and radiative forcing at Barrow, Alaska
Authors: Dong Xiquan , Xi Baike , Crosby Kathryn , Long Charles N. , Stone Robert S. , Shupe Matthew D.
Published: September 2010

A 10 year record of Arctic cloud fraction and radiative forcing has been generated using data collected at the Atmospheric Radiation Measurement (ARM) North Slope of Alaska site and the nearby NOAA Barrow Observatory (BRW) from June 1998 to May 2008. The cloud fractions (CFs) derived from ARM radar‐lidar and ceilometer measurements increase significantly from March to May (0.57→0.84), remain relatively high (∼0.80–0.9) from May to October, and then decrease from November to the following March (0.8→0.57), having an annual average of 0.76. These CFs are comparable to those derived from ground‐based radar‐lidar observations during the Surface Heat Budget of the Arctic Ocean experiment and from satellite observations over the western Arctic regions. The monthly means of estimated clear‐sky and measured all‐sky shortwave (SW)‐down and longwave (LW)‐down fluxes at the two facilities are almost identical with the annual mean differences less than 1.6 Wm−2. Values of LW cloud radiative forcing (CRF) are minimum (6 Wm−2) in March, then increase monotonically to reach maximum (63 Wm−2) in August, then decrease continuously to the following March. The cycle of SW CRF mirrors its LW counterpart with the greatest negative impact occurring during the snow‐free months of July and August. On annual average, the negative SW CRFs and positive LW CRFs nearly cancel, resulting in annual average NET CRF of about 3.5 Wm−2 on the basis of the combined ARM and BRW analysis. Compared with other studies, we find that LW CRF does not change over the Arctic regions significantly, but NET CRFs change from negative to positive from Alaska to the Beaufort Sea, indicating that Barrow is at a critical latitude for neutral NET CRF. The sensitivity study has shown that LW CRFs increase with increasing cloud fraction, liquid water path, and radiating temperature with high positive correlations (0.8–0.9). Negative correlations are found for SW CRFs, but a strong positive correlation between SW CRF and surface albedo exists.
Errors of Interannual Variability and Trend in Dynamical Downscaling of Reanalysis
Authors: Kanamitsu Masao , Yoshimura Kei , Yhang Yoo‐Bin , Hong Song‐You
Published: September 2010

The interannual variability of dynamically downscaled analysis and its error relative to global coarse resolution analysis is examined in this paper. The regional model error is shown to significantly contaminate the interannual variability of the seasonal mean. The error occupies a significant part of the interannual variability, particularly during the summer season. Accordingly, the leading modes of empirical orthogonal functions (EOFs) of 500 hPa height in the region differ greatly from those of global analysis. In this paper a variant of spectral nudging, the scale selective bias correction (SSBC) method, is refined to further reduce the error within the observational error. Application of this method in dynamical downscaling reduced the error of the interannual variability of analysis fields (namely, height, temperature, and winds), and made the EOFs of seasonal mean at 500 hPa height agree well with those of the global analysis. Application of the SSBC had a modest impact on model‐derived fields, such as precipitation and near‐surface air temperature. The improvements in these fields are not as dramatic as those in the analysis fields, but the increased simulation skill is evident. A possible cause of the error in the interannual variability is discussed. No apparent systematic reduction in high‐frequency variability is found, and the error in interannual variability is more likely due to excitation of the stationary computational mode by the lateral boundary forcing and ill‐posed lateral boundary condition.
High wintertime particulate matter pollution over an offshore island (Kinmen) off southeastern China: An overview
Authors: Hsu S. C. , Liu S. C. , Tsai F. , Engling G. , Lin I. I. , Chou C. K. C. , Kao S. J. , Lung S. C. C. , Chan C. Y. , Lin S. C. , Huang J. C. , Chi K. H. , Chen W. N. , Lin F. J. , Huang C. H. , Kuo C. L. , Wu T. C. , Huang Y. T.
Published: September 2010

Both the Yangtze River Delta (YRD) and the Pearl River Delta (PRD), the two most rapidly developing areas in eastern China, have suffered from serious air pollution, and thus, numerous investigations were devoted to studying these problems. Other areas in eastern China have received less attention despite similar rapid development in their industries and economy. In this study, we analyzed air‐quality data from Kinmen Island (24°27′26″N, 118°19′36″E) located off Fujian Province and between the two above‐mentioned deltas. Our results clearly show that the study area is experiencing serious air quality deterioration. Particularly, high levels of suspended particulate matter (PM) were observed during winter, when the northeasterly monsoon prevails. For example, concentrations of wintertime PM10 (particles ≤ 10 μm in diameter) frequently exceeded 100 μg/m3 in the last three years. In addition to the air‐quality data analysis, aerosol samples were collected between 22 November 2007 and 6 March 2008 and subjected to chemical analyses of various species. Our findings show that the three principal PM components include organic, mineral, and sulfate species with moderate to minor fractions of nitrate, sea salt, elemental carbon, and trace metal oxides. The high PM levels observed over the island may be partly attributed to the transport from a mixed‐type industrial area located ∼40 km northeast of Kinmen. Our study could partially fill the air quality data gap between the YRD and PRD regions, and highlight the alarming fact that air pollution has gradually expanded along eastern China's coastal zone.
Plasmid DNA vaccination using skin electroporation promotes poly‐functional CD4 T‐cell responses
Authors: Bråve Andreas , Nyström Sanna , Roos Anna‐Karin , Applequist Steven E
Published: September 2010

Plasmid DNA vaccination using skin electroporation (EP) is a promising method able to elicit robust humoral and CD8+ T‐cell immune responses while limiting invasiveness of delivery. However, there is still only limited data available on the induction of CD4+ T‐cell immunity using this method. Here, we compare the ability of homologous prime/boost DNA vaccinations by skin EP and intramuscular (i.m.) injection to elicit immune responses by cytokine enzyme‐linked immunosorbent spot (ELISPOT) assay, as well as study the complexity of CD4+ T‐cell responses to the human immunodeficiency virus antigen Gag, using multiparamater flow cytometry. We find that DNA vaccinations by skin EP and i.m. injection are capable of eliciting both single‐ and poly‐functional vaccine‐specific CD4+ T cells. However, although DNA delivered by skin EP was administered at a five‐fold lower dose it elicited significant increases in the magnitude of multiple‐cytokine producers compared with i.m. immunization suggesting that the skin EP could provide greater poly‐functional T‐cell help, a feature associated with successful immune defense against infectious agents.
Outer Spiral Disks as Clues to Galaxy Formation and Evolution
Authors: Vlajić Marija
Published: September 2010

Recent studies of outer spiral disks have given rise to an abundance of new results. We discuss the observational and theoretical advances that have spurred the interest in disk outskirts, as well as where we currently stand in terms of our understanding of outer disk structure, ages, and metallicities.
Role for the nuclear receptor-binding SET domain protein 1 (NSD1) methyltransferase in coordinating lysine 36 methylation at histone 3 with RNA polymerase II function
Authors: Lucio-Eterovic Agda Karina , Singh Melissa M. , Gardner Jeffrey E. , Veerappan Chendhore S. , Rice Judd C. , Carpenter Phillip B.
Published: September 2010

The NSD (nuclear receptor-binding SET domain protein) family encodes methyltransferases that are important in multiple aspects of development and disease. Perturbations in NSD family members can lead to Sotos syndrome and Wolf–Hirschhorn syndrome as well as cancers such as acute myeloid leukemia. Previous studies have implicated NSD1 (KMT3B) in transcription and methylation of histone H3 at lysine 36 (H3-K36), but its molecular mechanism in these processes remains largely unknown. Here we describe an NSD1 regulatory network in human cells. We show that NSD1 binds near various promoter elements and regulates multiple genes that appear to have a concerted role in various processes, such as cell growth/cancer, keratin biology, and bone morphogenesis. In particular, we show that NSD1 binding is concentrated upstream of gene targets such as the bone morphogenetic protein 4 (
BMP4
) and zinc finger protein 36 C3H type-like 1 (
ZFP36L1/TPP
). NSD1 regulates the levels of the various forms of methylation at H3-K36 primarily, but not exclusively, within the promoter proximal region occupied by NSD1. At
BMP4
we find that this reduces the levels of RNAP II recruited to the promoter, suggesting a role for NSD1-dependent methylation in initiation. Interestingly, we also observe that the RNAP II molecules that lie within
BMP4
have inappropriate persistence of serine-5 phosphorylation and reduced levels of serine-2 phosphorylation within the C-terminal domain (CTD) of the large subunit of RNAP II. Our findings indicate that NSD1 regulates RNAP II recruitment to
BMP4
, and failure to do so leads to reduced gene expression and abrogated levels of H3K36Me and CTD phosphorylation.
Replication allows inactivation of a knocked-in locus control region in inappropriate cell lineages
Authors: Menzel Ursula , Ktistaki Eleni , Tolaini Mauro , Veiga-Fernandes Henrique , Kioussis Dimitris
Published: September 2010

To study the influence of a locus control region (LCR) on the expression of a highly characterized, developmentally regulated locus, we have targeted the hCD2-LCR as a single copy into the endogenous mouse CD8 gene complex. Two knock-in mouse lines that differ in the integration site of the hCD2-LCR within the mCD8 gene complex were generated, and the influence on expression of the CD8 coreceptor was assessed. In these mice the normal developmental silencing of the CD8 genes in the CD4 lineage is deregulated, and the mice develop CD4+cells that also express the CD8 genes. This is accompanied by the physical maintenance of the CD8 genes within an extended loop away from their subchromosomal territory. Further analysis of these mice revealed unexpected fluid chromatin dynamics, whereby the LCR can be initially dominant over the endogenous CD8 gene-repressive regulatory processes present in CD4+cells but is continuously contested by them, resulting in the eventual inactivation of the inserted LCR, probably as a result of multiple rounds of replication.
Triton X-100 concentration effects on membrane permeability of a single HeLa cell by scanning electrochemical microscopy (SECM)
Authors: Koley Dipankar , Bard Allen J.
Published: September 2010

Changes in HeLa cell morphology, membrane permeability, and viability caused by the presence of Triton X-100 (TX100), a nonionic surfactant, were studied by scanning electrochemical microscopy (SECM). No change in membrane permeability was found at concentrations of 0.15 mM or lower during an experimental period of 30 to 60 min. Permeability of the cell membrane to the otherwise impermeable, highly charged hydrophilic molecule ferrocyanide was seen starting at concentrations of TX100 of about 0.17 mM. This concentration level of TX100 did not affect cell viability. Based on a simulation model, the membrane permeability for ferrocyanide molecules passing though the live cell membrane was 6.5 ± 2.0 × 10
-6
 m/s. Cells underwent irreversible permeabilization of the membrane and structural collapse when the TX100 concentration reached the critical micelle concentration (CMC), in the range of 0.19 to 0.20 mM. The impermeability of ferrocyanide molecules in the absence of surfactant was also used to determine the height and diameter of a single living cell with the aid of the approach curve and probe scan methods in SECM.