bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling the nucleation and crystallization kinetics of a palm stearin/canola oil blend and lard in bulk and emulsified form
Authors: Campbell Shawn D. , Douglas Goff H. , Rousseau Dérick
Published: December 2006

Using high‐pressure homogenization to generate different droplet size distributions, the nucleation and crystallization of two fat systems [lard or a plam stearin/canola oil blend (PSCO)] were compared in bulk and emulsified form. Droplet size reduction decreased the final volume fraction of solid fat primarily in the lard system vs. the PSCO system, with a greater reduction in volume fraction using the homogenization regime that led to smaller droplets. Homogeneous and heterogeneous models showed that the nucleation rate generally decreased with a reduction in droplet size. However, the Gibbs surface energy (γ) was significantly underestimated using the homogeneous model, whereas the heterogeneous model fit the data adequately (P<0.05). The temperature sensitivity of the calculated impurity concentration in all emulsified systems was droplet size dependent. The Avrami model showed the emulsified fats to have lower Avrami indices relative to the bulk fat as well as lower crystallization rate constants. Differences in the Avrami indices and the rate constants were more pronounced in the bulk and emulsified PSCO compared with lard.
Seed oil fatty acids of loasaceae—A new source of γ‐linolenic and stearidonic acids
Authors: Aitzetmüller K. , Brühl L. , Weigend M.
Published: December 2006

The pharmaceutically interesting Δ6‐FA 18∶3Δ6c, 9c, 12c (γ‐linolenic acid) and 18∶4Δ6c,9c,12c,15c (stearidonic acid) appear to have evolved independently several times during plant phylogenetic evolution. They typically occur in “clusters” of a few closely related species or genera in about a dozen different plant families throughout the plant kingdom. A hither‐unknown “cluster of occurrence” has now been discovered in the New World plant family Loasaceae. γ‐Linolenic and stearidonic acids occur exclusively in representatives of the newly described genus Nasa at significance levels of between 3 and 10% each. Nasa had recently been separated from the older, more broadly circumscribed genus Loasa. The two Δ6‐FA were not found in the closely related genus Loasa sensu stricto, nor in a number of other representatives of Loasaceae.
Simulation of batch physical refining and deodorization processes
Authors: Ceriani Roberta , Meirelles Antonio J. A.
Published: December 2006

This work presents an application of a differential distillation model for the simulation of batch physical refining and/or deodorization processes in the vegetable oil industry. The vapor‐liquid equilibria of these fat systems are described by group contribution equations for vapor pressures and activity coefficients published elsewhere, (Ceriani, R., and A.J.A. Meirelles, Predicting Vapor‐Liquid Equilibria of Fatty Systems, Fluid Phase Equilib. 215:227–236, 2004; Fredenslund, A., J. Gmehling, and P. Rasmussen, Vapor‐Liquid Equilibria Using UNIFAC, Elsevier Scientific, Amsterdam, 1977). The full complexity of the oil, expressed as its total composition of TAG, DAG, MAG, and FFA, is considered within the simulation. This approach permitted us to quantify and quality distillative neutral oil losses during physical refining. Three different models of differential distillation were tested to develop a good representation of the batch process to be applied to the physical refining and/or deodorization of complex mixtures such as vegetable oils. To evaluate the recommended approach, a case study was performed, namely, a batch deodorizer was simulated for coconut oil refining, and the results were compared with those reported in the literature.
Physical Properties of Polyurethanes Produced from Polyols from Seed Oils: I. Elastomers
Authors: Narine Suresh S. , Kong Xiaohua , Bouzidi Laziz , Sporns Peter
Published: December 2006

Polyols synthesized by ozonolysis and hydrogenation from canola oil were reacted with aliphatic 1,6‐hexamethylene diisocyanates (HDI) to produce polyurethane (PU) elastomers. The properties of the materials were examined by dynamic mechanical analysis (DMA), thermomechanical analysis (TMA), modulated differential scanning calorimetry (MDSC), and thermogravimetric analysis (TGA), and measurements were taken of tensile properties. The effect of dangling chains on network properties was assessed. The formation of hydrogen bonds was observed by FTIR. The measured properties were found to be strongly dependent on processing‐dependent factors such as the crosslinking density and the molar ratio of polyols to HDI component. The glass transition temperatures (Tg) of the elastomers were found to increase as the OH/NCO molar ratio decreased. With the same OH/NCO molar ratio, Tg of canola‐oil‐based PU was higher than that of soybean‐oil‐based PU. The TGA thermographs showed two well‐defined steps of degradation for all the elastomers. In the first step, up to 30% weight loss, the fastest rate of loss was found at 345 °C for canola‐oil‐based PU while soybean‐oil‐based PU lost most of the weight in the second step. With the same OH/NCO molar ratio, the elastomers made from canola‐oil‐based polyol showed slightly higher Young's modulus and tensile strength.
Polymeric Linoleic Acid–Polyolefin Conjugates: Cell Adhesion and Biocompatibility
Authors: Çakmaklı Birten , Hazer Baki , Tekin İshak Özel , Açıkgöz Şerefden , Can Murat
Published: December 2006

To diversify edible‐oil polymer composite, polymeric linoleic acid (PLina) peroxide was obtained by the auto‐oxidation of linoleic acid in a simple way for use as a macroinitiator in free radical polymerization of vinyl monomers. Peroxidation, epoxidation, and/or perepoxidation reactions of linoleic acid under air at room temperature resulted in PLina, having soluble fraction more than 91 weight percent (wt%), with molecular weight ranging from 1,644 to 2,763 Da, and containing up to 1.0 wt% of peroxide. PLina initiated the free radical polymerization of ether styrene (S), methyl methacrylate (MMA), or n‐butyl methacrylate (nBMA) to give PLina‐g‐polystyrene (PS), PLina‐g‐poly‐MMA (PMMA), and PLina‐g‐poly‐ nBMA (PnBMA) graft copolymers. The polymers obtained were characterized by proton nuclear magnetic resonance (1H NMR), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), and gel permeation chromatography (GPC) techniques. Microstructure of the graft copolymers was observed by using scanning electron microscope (SEM). Graft copolymers obtained contained polymeric linoleic acid in a range between 8.5 and 19.3 mol percent (mol%). PLina‐g‐PS, PLina‐g‐PMMA and PLina‐g‐PnBMA graft copolymer samples were also used in cell culture studies. Fibroblast and macrophage cells were strongly adhered and spread on the copolymer film surfaces. These newly synthesized copolymers were tested for their effects on human blood protein adsorption compared with PMMA graft copolymers containing polymeric soybean oil and polymeric linseed oil; interestingly we observed a dramatic decrease in the protein adsorption on the linoleic acid graft copolymer, which is important in tissue engineering.
Heat shock protein 70 inhibits the nuclear import of apoptosis‐inducing factor to avoid DNA fragmentation in TF‐1 cells during erythropoiesis
Authors: Lui Julian Chun-Kin , Kong Siu-Kai
Published: December 2006

Loss of mitochondrial membrane potential (ΔΨm) and release of AIF (apoptosis‐inducing factor) from mitochondria are key steps in apoptosis. In TF‐1 model, ΔΨm was depolarized with AIF release during erythroid development. Yet, no DNA fragmentation was observed. When ΔΨm depolarization had been blocked, erythropoiesis was suppressed. Interestingly, heat shock protein 70 (Hsp70) was found transiently upregulated during depolarization and it retained AIF in the cytosol to avoid DNA damages. When Hsp inhibitor was added, DNA fragmentation occurred. We show this mechanism for the first time in erythropoiesis how cells with ΔΨm depolarization and AIF release escape apoptosis.
Electoral Systems, District Magnitude and Corruption
Authors: CHANG ERIC C. C. , GOLDEN MIRIAM A.
Published: December 2006

The relationship between electoral systems and corruption in a large sample of contemporary democratic nations is analysed in this article. Whereas previous studies have shown that closed-list proportional representation is associated with greater (perceived) corruption than open-list PR, it is demonstrated here that this relationship fails to hold once district magnitude is considered. The theory underlying this study draws on work on ‘the personal vote’ that suggests that the incentives to amass resources – and perhaps even to do so illegally – increase with district magnitude in open-list settings but decrease in closed-list contexts. Extending this insight, it is shown that political corruption gets more (less) severe as district magnitude increases under open-list PR (closed-list PR) systems. In addition, once district magnitude exceeds a certain threshold – the estimates here are that this is as low as fifteen – corruption is greater under open lists than closed lists. Only at small district magnitudes (below fifteen) is closed-list PR associated with more corruption, as conventionally held. These results hold for alternative measures of corruption, for different sets of countries analysed, for different measures of district magnitude and regardless of whether the political system is presidential or parliamentary, and of the number of parties.

Using an objective measure of corruption in public works contracting, corroborating evidence is also presented from Italian electoral districts. In Italy's open-list environment in the period prior to 1994, larger districts were more susceptible to corruption than smaller ones.
Mobilization, Demobilization and the Economy in American Elections
Authors: STEVENS DANIEL
Published: December 2006

What motivates citizens to vote or abstain from voting? What determines vote choice? Models of turnout predominantly focus on a series of factors that affect perceptions of the benefits and costs of voting. The economy's influence on those perceptions has gone largely undeveloped. Models of vote choice routinely account for economic influences while ignoring turnout. This article presents a comprehensive analysis of the role of the economy as mobilizer and demobilizer. I argue that the economy has an impact on turnout decisions and that its impact is asymmetric. All else equal, the incumbent party is able to mobilize more supporters, relative to the non-incumbent party, in good economic times and more supporters are demobilized in adverse economic times. However, Democrats and Republicans are not sensitive to the same elements of economic performance. This is in part a function of the way in which the economy influences perceptions of the closeness of the impending election and of the candidates and their parties. Analysis of pooled data from ANES surveys for the twelve presidential elections from 1956 to 2000 confirms the validity of these arguments.
Cross-linguistic tendencies and durational contrasts in geminate consonants: an examination of Guinaang Bontok geminates
Authors: Aoyama Katsura , Reid Lawrence A.
Published: December 2006

In Guinaang Bontok, there is a phonological contrast between singletons and geminates in all consonants (/p t k ? b d g m n ŋ l s w j/) (Reid 1963, 1973; Thurgood 1997). All phonological geminates except for the oral voiced stop geminates are phonetically long consonants (Reid 1963), allowing a phonological distinction which is primarily based on phonetic duration for nasals, fricatives, liquids, glides and voiceless stops. In a cross-linguistic examination of geminates (Thurgood 1993), there were more languages listed as examples for having stop and nasal geminates than for glide geminates, and it was suggested that alveolar was the cross-linguistically preferred place of articulation for geminate consonants. In this study, it was hypothesized that the cross-linguistically less common length contrasts, such as the length contrasts in glides, were phonetically less clear than the more common ones, such as contrasts between short and long stop and nasal consonants. Similarly, it was hypothesized that contrasts in the cross-linguistically common place of articulation (i.e. alveolar) is phonetically clearer than less common contrasts (e.g. velar). In order to test these hypotheses, duration measurements were conducted on single and geminate consonants in Guinaang Bontok. The average durational contrast between short and long glides was smaller than the contrast in stop and nasal consonants. The hypothesis was therefore partially supported.
The North Wind versus a Wolf: short texts for the description and measurement of English pronunciation
Authors: Deterding David
Published: December 2006

For many years, the passage ‘The North Wind and the Sun’ (NWS) has been used for phonetic research into different languages. However, there are many shortcomings with the passage for the description of varieties of English, including the absence of some sounds, such as /[zcy ]/ and syllable-initial /θ/, problems with the text for the measurement of rhythm, and issues regarding acoustic measurements of /æ/ and /I/. An alternative passage, ‘The Boy who Cried Wolf’, is suggested, and measurements of the monophthongs based on recordings of the Wolf passage by three RP British English speakers are compared with similar measurements of the vowels in the NWS passage.
Status and distribution of the White-bellied Shortwing Brachypteryx major in the Western Ghats of Karnataka and Goa, India
Authors: ROBIN V. V. , SUKUMAR R. , THIOLLAY J.-M.
Published: December 2006

The White-bellied Shortwing is a Globally Threatened, endemic bird found in the Western Ghats of southern India. Given the few recent records of the species from its range, its population is thought to have dwindled with increasing habitat fragmentation and disturbance. A previous survey covered the states of Kerala and Tamil Nadu while this survey covers the states of Karnataka and Goa; thus together the two surveys cover the species' entire prospective range. The survey resulted in 11 sightings of White-bellied Shortwing in the unique shola forests. Encounter rates in Karnataka were much lower than in Kerala and Tamil Nadu, while no shortwings were sighted in Goa. Effects of sampling effort and detectability were examined as probable causes of the low encounter rates and one site was re-sampled. Conservation problems are highlighted and suggestions are made.
ACCIDENT LAW FOR EGALITARIANS
Authors: Avraham Ronen , Kohler-Hausmann Issa
Published: December 2006

This paper questions the fairness of our current tort-law regime and the philosophical underpinnings advanced in its defense, a theory known as corrective justice. Fairness requires that the moral equality and responsibility of persons be respected in social interactions and institutions. The concept of luck has been used by many egalitarians as a way of giving content to fairness by differentiating between those benefits and burdens that result from informed choice and those that result from fate or fortune. We argue that the theory of corrective justice, along with its institutional embodiment of tort law, is at odds with an egalitarian commitment to fairness because it allows luck an unjustifiable role in determining dissimilar liability for similar wrongs and dissimilar compensation for similar losses to bodily integrity. Many egalitarian political theorists have also recognized, if not defended, the notion of distinct forms of justice, namely corrective, retributive, and distributive. Although theorists of these different forms of justice have been concerned with negating unfair luck inside the operations of each form of justice, there has been little attention to the way in which luck operates to sort cases into each form of justice. We claim that there is a significant way in which luck operates to subject different people to principles of corrective, retributive, and distributive justice—thereby assessing dissimilar liability for similar wrongs and disparate compensation for similar losses—which flies in the face of the egalitarian value of fairness. After surveying the arguments put forward by theorists defending a categorical distinction between corrective justice and retributive and distributive principles, we argue that although analytical distinctions can be made between different forms of justice (although, we also suggest that the distinctions are not as sharp as some commentators suggest), there is no good reason to defend an acoustic separation between these forms of justice when doing so creates unfair outcomes.
Bilateral breast reconstruction
Authors: Disa J. J. , McCarthy C. M.
Published: December 2006

According to the American Cancer Society, more than 211 000 women in the USA were diagnosed with invasive breast cancer in 2005, (American Cancer Society. www.cancer.org. 2005). Nearly 65 000 of these women had postmastectomy reconstruction – a 100% increase from just over a decade ago, (American Society of Plastic Surgeons. www.plasticsurgery.org. 2005). A significant proportion of these women, will elect to undergo bilateral mastectomy for treatment and/or prophylaxis of breast cancer. Contemporary techniques provide numerous options for bilateral, postmastectomy reconstruction. Procedure selection will be based on a range of patient variables, including: availability of local, regional, and distant donor tissues for bilateral reconstruction, size and shape of the desired breasts, surgical risk, and most importantly, patient preference. Ultimately, the individualized selection of a reconstructive technique for each patient is a predominant factor in achieving a reconstructive success.
Darmdiagnostik – Kapselendoskopie
Authors: Riemann  , Rosenbaum
Published: December 2006

Durch die Videokapselendoskopie ist nun auch der Dünndarm leichter einer endoskopischen Diagnostik zugänglich, mit der Einschränkung, dass bislang keinerlei Interventionen möglich sind. Allen verfügbaren Daten zufolge ist diese Methode bezüglich der diagnostischen Ausbeute der Push-Enteroskopie und der radiologischen Diagnostik überlegen. Bei der Abklärung obskurer gastrointestinaler Blutungen werden ähnliche Ergebnisse erzielt wie mit der intraoperativen Enteroskopie. Der Stellenwert der neuen Methode zur Diagnostizierung des Morbus Crohn ist noch nicht geklärt, da bis dato keine Outcome-Studien vorliegen. In Zukunft werden technische Weiterentwicklungen die Anwendungsmöglichkeiten der Kapselendoskopie wohl noch deutlich erweitern.
Theoretical fluxes of gamma rays from the Martian surface
Authors: Kim Kyeong J. , Drake Darrell M. , Reedy Robert C. , Williams Remo M. S. , Boynton William V.
Published: December 2006

Theoretical fluxes of gamma rays escaping the surface of Mars were calculated. These and other calculated fluxes are needed to model the counting rates in the Mars Odyssey gamma ray spectrometer that are used to determine elemental compositions and other results using these measurements. Cross sections for the formation of gamma rays by both thermal and fast neutrons were compiled and evaluated. These evaluated cross sections were used with neutron fluxes calculated with the Monte Carlo N Particle Extended (MCNPX) code to get gamma ray production rates as a function of depth in the Martian surface. The fluxes of these gamma rays as a function of angle at the Martian surface were then calculated using gamma ray attenuation coefficients.
Validating land cover maps with Degree Confluence Project information
Authors: Iwao Koki , Nishida Kenlo , Kinoshita Tsuguki , Yamagata Yoshiki
Published: December 2006

We propose the use of Degree Confluence Project (hereby DCP) information as a new method for validating land cover maps. The DCP is a volunteer‐based project that aims to collect onsite information from all the degree confluences (intersections of integer level latitude and longitude gridlines) in the world. We assessed the reliability and effectiveness of DCP‐derived data in validating land cover maps. As a result, we obtained land cover validation information superior to the validation information obtained by visual interpretation of Landsat images. By using DCP‐derived validation information (at 749 confluences), we evaluated existing land cover maps for Eurasia (GLC2000, MOD12, UMD, and GLCC). The agreements between the DCP‐derived validation information and the land cover maps were 55% for GLC2000, 58% for MOD12, 54% for UMD, and 50% for GLCC. Although MOD12 and GLC2000 had somewhat better agreements than the other maps, there is no significant difference between the two.
Interpretation of tropical thermocline cooling in the Indian and Pacific oceans during recent decades
Authors: Han Weiqing , Meehl Gerald A. , Hu Aixue
Published: December 2006

A warming trend has been detected in the world's oceans in recent decades. The basin‐averaged warming, however, shows a complex vertical structure in the Indian and Pacific oceans. Warming in the upper ocean‐with maxima near the surface‐ accompanies a strong cooling in the upper thermocline. Analysis of observed data and model solutions from this study reveals that the complex structure is confined mainly to the tropics. While increased greenhouse gases act to warm up the upper ocean by increasing downward surface heat fluxes, anomalous winds in the tropics cause upward Ekman pumping velocity and shoal the thermocline, resulting in an upper‐thermocline cooling. This cooling process is well demonstrated by a simple model based on the ventilated thermocline theory. The study has important implications for climate change and fisheries.
Observations of colocated optical and radar aurora
Authors: Bahcivan H. , Hysell D. L. , Lummerzheim D. , Larsen M. F. , Pfaff R. F.
Published: December 2006

This article presents case studies of common volume observations of the E region radar aurora obtained with a 30 MHz imaging radar and the optical aurora (green line emissions) recorded by an all sky camera. In addition, in situ rocket electric field measurements in the vicinity of an auroral arc are presented in a separate case study. As inferred from the measurements, the radar aurora in the vicinity of a stable evening auroral arc arises because of the arc's polarization electric fields, which excite the two stream instability and generate electron density irregularities at meter scales. The radar aurora is the backscattering of radar waves from these irregularities.
Water mass and throughflow transport variability in the Taiwan Strait
Authors: Jan Sen , Sheu David D. , Kuo Huei‐Ming
Published: December 2006

Variability of water mass and throughflow transport in the Taiwan Strait are analyzed using strait‐wide conductivity‐temperature‐depth (1985–2003) and sectional acoustic Doppler current profiler (1999–2001) data. Results from a cluster analysis, temperature‐salinity diagrams, and direct transport calculations indicate that the strong northeast monsoon drives the brackish Mixed China Coastal Water into the northern strait and hinders the northward intruded saline Kuroshio Branch Water (KBW) in the southeastern strait from December to January. The mean throughflow transport across the central strait is about 0.1 Sv southward during this period, thus supporting previous observations that there is no persistent northward flowing current throughout the strait in winter. The weakening of the northeast monsoon in February–March, however, emancipates the KBW to intrude northward into the East China Sea (ECS). In June, the increase in this northward transport accompanied by the decrease in the westward intrusion of Kuroshio through the Luzon Strait leads to the replacement of the KBW by the less saline South China Sea Water (SCSW). The northward transports ranging from 1.16 to 2.34 Sv between March and August yield 0.131–0.238 × 1015 W and 53.33–81.74 × 106 kg/s of temperature and salt transports, respectively, toward the ECS. The inception of the northeast monsoon in October marks both the change of water mass from fall to winter patterns and the decrease of the northward throughflow transport. Our results also reveal that the subsurface KBW and SCSW remain consistent throughout the observation periods between 100 and 200 m and below 200 m depths, respectively, in the southeastern strait.
C-terminal region regulates the functional expression of human noradrenaline transporter splice variants
Authors: Sogawa Chiharu , Kumagai Kei , Sogawa Norio , Morita Katsuya , Dohi Toshihiro , Kitayama Shigeo
Published: December 2006

The NET [noradrenaline (norepinephrine) transporter], an Na+/Cl−-dependent neurotransmitter transporter, has several isoforms produced by alternative splicing in the C-terminal region, each differing in expression and function. We characterized the two major isoforms of human NET, hNET1, which has seven C-terminal amino acids encoded by exon 15, and hNET2, which has 18 amino acids encoded by exon 16, by site-directed mutagenesis in combination with NE (noradrenaline) uptake assays and cell surface biotinylation. Mutants lacking one third or more of the 24 amino acids encoded by exon 14 exhibited neither cell surface expression nor NE uptake activity, with the exception of the mutant lacking the last eight amino acids of hNET2, whose expression and uptake resembled that of the WT (wild-type). A triple alanine replacement of a candidate motif (ENE) in this region mimicked the influences of the truncation. Deletion of either the last three or another four amino acids of the C-terminus encoded by exon 15 in hNET1 reduced the cell surface expression and NE uptake, whereas deletion of all seven residues reduced the transport activity but did not affect the cell surface expression. Replacement of RRR, an endoplasmic reticulum retention motif, by alanine residues in the C-terminus of hNET2 resulted in a similar expression and function compared with the WT, while partly recovering the effects of the mutation of ENE. These findings suggest that in addition to the function of the C-terminus, the common proximal region encoded by exon 14 regulates the functional expression of splice variants, such as hNET1 and hNET2.
The Spn4 gene from Drosophila melanogaster is a multipurpose defence tool directed against proteases from three different peptidase families
Authors: Brüning Mareke , Lummer Martina , Bentele Caterina , Smolenaars Marcel M. W. , Rodenburg Kees W. , Ragg Hermann
Published: December 2006

By alternative use of four RSL (reactive site loop) coding exon cassettes, the serpin (serine protease inhibitor) gene Spn4 from Drosophila melanogaster was proposed to enable the synthesis of multiple protease inhibitor isoforms, one of which has been shown to be a potent inhibitor of human furin. Here, we have investigated the inhibitory spectrum of all Spn4 RSL variants. The analyses indicate that the Spn4 gene encodes inhibitors that may inhibit serine proteases of the subtilase family (S8), the chymotrypsin family (S1), and the papain-like cysteine protease family (C1), most of them at high rates. Thus a cohort of different protease inhibitors is generated simply by grafting enzyme-adapted RSL sequences on to a single serpin scaffold, even though the target proteases contain different types and/or a varying order of catalytic residues and are descendents of different phylogenetic lineages. Since all of the Spn4 RSL isoforms are produced as intracellular residents and additionally as variants destined for export or associated with the secretory pathway, the Spn4 gene represents a versatile defence tool kit that may provide multiple antiproteolytic functions.
Lovastatin inhibits the extracellular-signal-regulated kinase pathway in immortalized rat brain neuroblasts
Authors: Cerezo-Guisado Maria Isabel , GarcíA-Román Natalia , García-MaríN Luis Jesús , Álvarez-Barrientos Alberto , Bragado Maria Julia , Lorenzo Maria Jesús
Published: December 2006

We have shown previously that lovastatin, a 3-hydroxy-3-methyl- glutaryl coenzyme A reductase inhibitor, induces apoptosis in spontaneously immortalized rat brain neuroblasts. In the present study, we analysed the intracellular signal transduction pathways by which lovastatin induces neuroblast apoptosis. We showed that lovastatin efficiently inhibited Ras activation, which was associ-ated with a significant decrease in ERK1/2 (extracellular-signal-regulated kinase 1/2) phosphorylation. Lovastatin also decreased CREB phosphorylation and CREB-mediated gene expression. The effects of lovastatin on the Ras/ERK1/2/CREB pathway were time- and concentration-dependent and fully prevented by meva-lonate. In addition, we showed that two MEK [MAPK (mitogen-activated protein kinase)/ERK kinase] inhibitors, PD98059 and PD184352, were poor inducers of apoptosis in serum-treated neuroblasts. However, these inhibitors significantly increased apop-tosis induced by lovastatin treatment. Furthermore, we showed that pharmacological inhibition of both MEK and phosphoinos-itide 3-kinase activities was able to induce neuroblast apoptosis with similar efficacy as lovastatin. Our results suggest that lovast-atin triggers neuroblast apoptosis by regulating several signalling pathways, including the Ras/ERK1/2 pathway. These findings might also contribute to elucidate the intracellular mechanisms involved in the central nervous system side effects associated with statin therapy.
Differential involvement of thrombin receptors in Ca2+ release from two different intracellular stores in human platelets
Authors: Jardin Isaac , Ben Amor Nidhal , Bartegi Ahgleb , Pariente José A. , Salido Ginés M. , Rosado Juan A.
Published: December 2006

Physiological agonists increase cytosolic free Ca2+ concentration to regulate a number of cellular processes. The platelet thrombin receptors, PAR (protease-activated receptor) 1 PAR-4 and GPIb-IX-V (glycoprotein Ib-IX-V) have been described as potential contributors of thrombin-induced platelet aggregation. Platelets present two separate Ca2+ stores, the DTS (dense tubular system) and acidic organelles, differentiated by the distinct sensitivity of their respective SERCAs (sarcoplasmic/endoplasmic-reticulum Ca2+-ATPases) to TG (thapsigargin) and TBHQ [2,5-di-(tert-butyl)-1,4-hydroquinone]. However, the involvement of the thrombin receptors in Ca2+ release from each Ca2+ store remains unknown. Depletion of the DTS using ADP, which releases Ca2+ solely from the DTS, in combination with 10 nM TG, to selectively inhibit SERCA2 located on the DTS reduced Ca2+ release evoked by the PAR-1 agonist, SFLLRN, and the PAR-4 agonist, AYPGKF, by 80 and 50% respectively. Desensitization of PAR-1 and PAR-4 or pre-treatment with the PAR-1 and PAR-4 antagonists SCH 79797 and tcY-NH2 reduced Ca2+ mobilization induced by thrombin, and depletion of the DTS after desensitization or blockade of PAR-1 and PAR-4 had no significant effect on Ca2+ release stimulated by thrombin through the GPIb-IX-V receptor. Converse experiments showed that depletion of the acidic stores using TBHQ reduced Ca2+ release evoked by SFLLRN or AYPGKF, by 20 and 50% respectively, and abolished thrombin-stimulated Ca2+ release through the GPIb-IX-V receptor when PAR-1 and PAR-4 had been desensitized or blocked. Our results indicate that thrombin-induced activation of PAR-1 and PAR-4 evokes Ca2+ release from both Ca2+ stores, while activation of GPIb-IX-V by thrombin releases Ca2+ solely from the acidic compartments in human platelets.
Interactions between substrates and the haem-bound nitric oxide of ferric and ferrous bacterial nitric oxide synthases
Authors: Chartier François J. M. , Couture Manon
Published: December 2006

We report here the resonance Raman spectra of the FeIII–NO and FeII–NO complexes of the bacterial NOSs (nitric oxide synthases) from Staphylococcus aureus and Bacillus subtilis. The haem–NO complexes of these bacterial NOSs displayed Fe–N–O frequencies similar to those of the mammalian NOSs, in presence and absence of L-arginine, indicating that haem-bound NO and L-arginine had similar haem environments in bacterial and mammalian NOSs. The only notable difference between the two types of NOS was the lack of change in Fe–N–O frequencies of the FeIII–NO complexes upon (6R) 5,6,7,8-tetrahydro-L-biopterin binding to bacterial NOSs. We report, for the first time, the characterization of NO complexes with NOHA (Nω-hydroxy-L-arginine), the substrate used in the second half of the catalytic cycle of NOSs. In the FeIII–NO complexes, both L-arginine and NOHA induced the Fe–N–O bending mode at nearly the same frequency as a result of a steric interaction between the substrates and the haem-bound NO. However, in the FeII–NO complexes, the Fe–N–O bending mode was not observed and the νFe−NO mode displayed a 5 cm−1 higher frequency in the complex with NOHA than in the complex with L-arginine as a result of direct interactions that probably involve hydrogen bonds. The different behaviour of the substrates in the FeII–NO complexes thus reveal that the interactions between haem-bound NO and the substrates are finely tuned by the geometry of the Fe-ligand structure and are relevant to the use of the FeII–NO complex as a model of the oxygenated complex of NOSs.
Binding of calcium ions and SNAP-25 to the hexa EF-hand protein secretagogin
Authors: Rogstam Annika , Linse Sara , Lindqvist Anders , James Peter , Wagner Ludwig , Berggård Tord
Published: December 2006

Secretagogin is a hexa EF-hand protein, which has been identified as a novel potential tumour marker. In the present study, we show that secretagogin binds four Ca2+ ions (log K1=7.1±0.4, log K2=4.7±0.6, log K3=3.6±0.7 and log K4=4.6±0.6 in physiological salt buffers) with a [Ca2+]0.5 of approx. 25 μM. The tertiary structure of secretagogin changes significantly upon Ca2+ binding, but not upon Mg2+ binding, and the amount of exposed hydrophobic surface in secretagogin increases upon Ca2+ binding, but not upon Mg2+ binding. These properties suggest that secretagogin belongs to the ‘sensor’ family of Ca2+-binding proteins. However, in contrast with the prototypical Ca2+ sensor calmodulin, which interacts with a very large number of proteins, secretagogin is significantly less promiscuous. Only one secretagogin-interacting protein was reproducibly identified from insulinoma cell lysates and from bovine and mouse brain homogenates. This protein was identified as SNAP-25 (25 kDa synaptosome-associated protein), a protein involved in Ca2+-induced exocytosis in neurons and in neuroendocrine cells. Kd was determined to be 1.2×10−7 M in the presence of Ca2+ and 1.5×10−6 M in the absence of Ca2+. The comparatively low Ca2+ affinity for secretagogin and the fact that it undergoes Ca2+-induced conformational changes and interacts with SNAP-25 raise the possibility that secretagogin may link Ca2+ signalling to exocytotic processes.
Copper binding to the N-terminal metal-binding sites or the CPC motif is not essential for copper-induced trafficking of the human Wilson protein (ATP7B)
Authors: Cater Michael A. , La fontaine Sharon , Mercer Julian F. B.
Published: December 2006

The Wilson protein (ATP7B) is a copper-translocating P-type ATPase that mediates the excretion of excess copper from hep-atocytes into bile. Excess copper causes the protein to traffic from the TGN (trans-Golgi network) to subapical vesicles. Using site-directed mutagenesis, mutations known or predicted to abrogate catalytic activity (copper translocation) were introduced into ATP7B and the effect of these mutations on the intracellular traf-ficking of the protein was investigated. Mutation of the critical aspartic acid residue in the phosphorylation domain (DKTGTIT) blocked copper-induced redistribution of ATP7B from the TGN, whereas mutation of the phosphatase domain [TGE (Thr-Gly-Glu)] trapped ATP7B at cytosolic vesicular compartments. Our findings demonstrate that ATP7B trafficking is regulated with its copper-translocation cycle, with cytosolic vesicular localization associated with the acyl-phosphate intermediate. In addition, mut-ation of the six N-terminal metal-binding sites and/or the trans-membrane CPC (Cys-Pro-Cys) motif did not suppress the consti-tutive vesicular localization of the ATP7B phosphatase domain mutant. These results suggested that copper co-ordination by these sites is not essential for trafficking. Importantly, copper-chelation studies with these mutants clearly demonstrated a requirement for copper in ATP7B trafficking, suggesting the presence of an additional copper-binding site(s) within the protein. The results presented in this report significantly advance our understanding of the regulatory mechanism that links copper-translocation activity with copper-induced intracellular trafficking of ATP7B, which is central to hepatic and hence systemic copper homoeostasis.
Role of the cysteine residues in Arabidopsis thaliana cyclophilin CYP20-3 in peptidyl-prolyl cis–trans isomerase and redox-related functions
Authors: Laxa Miriam , König Janine , Dietz Karl-Josef , Kandlbinder Andrea
Published: December 2006

Cyps (cyclophilins) are ubiquitous proteins of the immunophilin superfamily with proposed functions in protein folding, protein degradation, stress response and signal transduction. Conserved cysteine residues further suggest a role in redox regulation. In order to get insight into the conformational change mechanism and functional properties of the chloroplast-located CYP20-3, site-directed mutagenized cysteine→serine variants were generated and analysed for enzymatic and conformational properties under reducing and oxidizing conditions. Compared with the wild-type form, elimination of three out of the four cysteine residues decreased the catalytic efficiency of PPI (peptidyl-prolyl cis–trans isomerase) activity of the reduced CYP20-3, indicating a regulatory role of dithiol–disulfide transitions in protein function. Oxidation was accompanied by conformational changes with a predominant role in the structural rearrangement of the disulfide bridge formed between Cys54 and Cys171. The rather negative Em (midpoint redox potential) of −319 mV places CYP20-3 into the redox hierarchy of the chloroplast, suggesting the activation of CYP20-3 in the light under conditions of limited acceptor availability for photosynthesis as realized under environmental stress. Chloroplast Prx (peroxiredoxins) were identified as interacting partners of CYP20-3 in a DNA-protection assay. A catalytic role in the reduction of 2-Cys PrxA and 2-Cys PrxB was assigned to Cys129 and Cys171. In addition, it was shown that the isomerization and disulfide-reduction activities are two independent functions of CYP20-3 that both are regulated by the redox state of its active centre.
A sharper instrument for dissecting signalling events: a specific AGC kinase inhibitor
Authors: Proud Christopher G.
Published: December 2006

Small-molecule inhibitors are now widely used to try to dissect regulatory signalling events. Many of these interfere with the function of protein kinases, often as part of signalling cascades. In addition to their utility as tools for the researcher, the long-term aspiration is that certain of these compounds may be useful as therapeutic agents for the treatment of conditions that arise from the dysregulation of specific signalling pathways. In this issue of the Biochemical Journal, Sapkota and colleagues report the identification and initial validation of a compound that inhibits the RSK (p90 ribosomal S6 kinase) group of protein kinases, which are members of an important family of kinases (the ‘AGC kinases’) that have overlapping specificities.
Minimal redefinition of the OSV ensemble
Authors: Parvizi Shahrokh , Tavanfar Alireza
Published: December 2006

In the interesting conjecture, ZBH=|Ztop|2, proposed by Ooguri, Strominger, and Vafa (OSV), the black hole ensemble is a mixed ensemble. So if working in the complex polarization, the black hole degeneracy of states as obtained from the ensemble inverse-Laplace integration, generically receives prefactors that do not respect the electric-magnetic duality. One way to handle this, as claimed recently, is working instead of the complex polarization in the real polarization. The other idea would be imposing nontrivial measures for the ensemble sum in the complex polarization. We address this problem in the complex polarization, which is canonical, and upon a redefinition of the OSV ensemble with variables as numerous as the electric potentials, show that for restoring the symmetry no non-Euclidean measure is needed. In detail, applying the electric-magnetic duality as a constraint governing the proper definition of the ensemble variables, we rewrite the OSV free energy as a function of new variables that are combinations of the electric potentials and the black hole charges. Subsequently the Legendre transformation, which bridges between the entropy and the black hole free energy in terms of these variables, points to a generalized ensemble that is well behaved in the complex polarization. In this context, we will consider all the cases of relevance: small and large black holes, with or without D6-brane charge. For the case of vanishing D6-brane, the new ensemble is purely canonical and the electric-magnetic duality is restored exactly, leading to proper results for the black hole degeneracy of states to all orders in an asymptotic expansion. For more general cases as well, the construction does the job as far as the violation of the duality by the corresponding OSV result is restricted to a prefactor. In the case of black holes with nonvanishing D6-brane charge, in a concrete example, we shall show that there are cases where the duality violation goes beyond this restriction and imposing nontrivial measures is incapable of restoring the duality.
Stability of parallel wake flows in quasigeostrophic and frontal regimes
Authors: Perret G. , Stegner A. , Dubos T. , Chomaz J. M. , Farge M.
Published: December 2006

Recent laboratory experiments [G. Perret, A. Stegner, M. Farge, and T. Pichon, Phys. Fluids 18, 036603 (2006)] have shown that the vortex-street formed in the wake of a towed cylinder in a rotating shallow-water layer could present a strong cyclone-anticyclone asymmetry. In extreme cases, only large-scale anticyclones were observed in the far wake. This asymmetry occurs in the so-called frontal regime when the Rossby number is small and the surface deviation is large. This asymmetry may have various origins and in particular may be attributed to the asymmetry of the flow around the cylinder, to the linear stability property of the wake, or to its nonlinear evolution. To discriminate between these mechanisms, we study the stability of two idealized parallel flows in the quasigeostrophic and in the frontal regimes. These parallel flows correspond to two velocity profiles measured just behind the cylinder in a region where the perturbations are negligible. According to our linear stability analysis, the most unstable mode, in the frontal regime, is localized in the anticyclonic shear region whether the base flow profile is symmetric or not. On a linear basis, it is thus more the instability that imposes the asymmetry than the base flow. Direct numerical simulations of the synthetic parallel wake flows show that nonlinearity exacerbates the dominance of the anticyclonic mode linearly selected. By numerically studying the spatio-temporal evolution of a small perturbation localized in space, we show that, unlike incompressible two–dimensional wake flows and the symmetric wake in the quasigeostrophic regime, the parallel asymmetric wake is strongly convectively unstable in the frontal regime, and not absolutely unstable. When the surface deformation becomes large, the wake instability changes from the absolute instability in the quasi-geostrophic regime to the strongly convective instability of the frontal regime. This explains well the changes.
Structural properties of Ge nanocrystals embedded in sapphire
Authors: Sharp I. D. , Xu Q. , Yi D. O. , Yuan C. W. , Beeman J. W. , Yu K. M. , Ager J. W. , Chrzan D. C. , Haller E. E.
Published: December 2006

Isotopically pure Ge74 nanocrystals were formed in a sapphire matrix by the ion beam synthesis method. In contrast to those embedded in amorphous silica, sapphire-embedded nanocrystals are clearly faceted and are preferentially oriented with respect to the crystalline matrix. In situ transmission electron microscopy of heated samples reveals that the nanocrystals melt at 955±15°C, very near to the bulk Ge melting point. The Raman spectra indicate that the sapphire-embedded Ge nanocrystals are under compressive stress in the range of 3–4GPa. The magnitude of the stress is consistent with that expected for hydrostatic pressure arising from solidification. Stress relaxation was not observed for sapphire-embedded Ge nanocrystals; this is attributed to the slow self-diffusion rate of the alumina matrix atoms at temperatures below the nanocrystal melting point.
Structural and electrical properties of neodymium oxide high-k gate dielectrics
Authors: Pan Tung-Ming , Lee Jian-Der , Shu Wei-Hao , Chen Tsung-Te
Published: December 2006

In this letter, the authors reported a high-k neodymium oxide gate dielectric grown by reactive rf sputtering. It is found that the Nd2O3 gate dielectric after annealing at 700°C exhibits excellent electrical properties such as low equivalent oxide thickness, high electric breakdown field, and almost no hysteresis and frequency dispersion in C-V curves. This indicates that annealing at 700°C treatment can prevent the interfacial layer and silicate formation, reduce a large amount of interface trap, and passivate a large amount of trapped charge at defect sites.
Angular momentum and geometrical phases in tight-focused circularly polarized plane waves
Authors: Bomzon Ze’ev , Gu Min , Shamir Joseph
Published: December 2006

Calculations for the field at the focal plane of a high numerical aperture lens focusing a circularly polarized plane wave are presented. The calculations show that the polarization of the wave front in the focal plane is space varying, and that a geometrical phase is added to the wave front. Calculation of the angular momentum at the focal plane reveals that it depends on the numerical aperture of the lens. It is shown that this dependence is directly connected to the lens acting as a spatial filter.
Spectroscopic infrared near-field microscopy and x-ray reflectivity studies of order and clustering in lipid membranes
Authors: Generosi J. , Margaritondo G. , Sanghera J. S. , Aggarwal I. D. , Tolk N. H. , Piston D. W. , Castellano A. Congiu , Cricenti A.
Published: December 2006

Lipid membranes were studied by infrared scanning near-field optical microscopy at several wavelengths and by x-ray reflectivity. Together with the x-ray data, the optical images indicate the formation of locally ordered multiple bilayers, and the topographical micrographs reveal the presence of islands at the surface, both critically important features for biotechnology and medical applications such as biosensors and gene therapy.
Nucleation mechanism for reconstructive solid-solid phase transitions via melt mediated nanocluster transformation
Authors: Levitas Valery I. , Smilowitz Laura B. , Henson Bryan F. , Asay Blaine W.
Published: December 2006

A general nucleation mechanism is proposed and justified thermodynamically and kinetically. The authors apply it to the β-δ phase transformation (PT) in the HMX crystal. It explains the observation of a reconstructive PT very close (0.6K) to the phase equilibrium temperature, despite the large volume change and interface energy. Nanosize clusters of β phase dissolve in a liquid and transform into δ phase clusters. The liquid completely removes the elastic energy generated by a large volume change. Cluster to cluster PT also drastically reduces the change in interfacial energy. Suggested kinetics for the β-δ PT is in good agreement with experiments.