bluuebunny/crossref_metadata_2025 huggingface dataset:
Photorespiration
Authors: Bauwe Hermann
Published: February 2010

Photorespiration is the light‐dependent release of carbon dioxide initiated by
ribulose‐1,5‐bisphosphate carboxylase/oxygenase
(
Rubisco
) in oxygen‐producing photosynthetic organisms. It occurs because oxygen can substitute for carbon dioxide in the first reaction of the photosynthetic carbon dioxide‐fixation process, causing the idle synthesis of phosphoglycolate. Phosphoglycolate is scavenged in the photorespiratory C
2
cycle, which is an essential auxiliary metabolic pathway that allows photosynthesis in oxygen‐containing environments. Three out of four misdirected carbon atoms are recovered and the fourth is released as photorespiratory carbon dioxide. Absolute rates vary in different organisms and they also depend on environmental conditions, mainly oxygen, carbon dioxide and temperature. They are highest in C
3
plants and much reduced in other organisms, such as C
4
plants, algae and cyanobacteria. In the presence of oxygen, phosphoglycolate production is unavoidable and cannot be eliminated.

Key concepts:

Nearly all photosynthetic activity on earth is oxygen‐producing photosynthesis. Dictated by the biochemistry of carbon dioxide fixation, this unavoidably comes with the production of phosphoglycolate.

When assessed by mass flow, excelled only by photosynthesis, phosphoglycolate production constitutes the second‐most important process in the land‐based biosphere.

The scavenging of phosphoglycolate was a condition for the evolution of cyanobacteria, algae and plants.

Oxygenic photosynthesis is only possible on the condition of adequate photorespiratory metabolism and life on earth would look very different without it.

Oxygenic photosynthesis is coupled to photorespiratory carbon dioxide losses and this reduces competitiveness of C
3
plants in warm environments. Gene technology‐assisted breeding hopes to reduce these losses in crops.
Deep Subseafloor Microbial Communities
Authors: Inagaki Fumio
Published: February 2010

Marine subsurface sediments cover approximately 70% of the Earth surface and harbour a remarkable population of microbial life that comprises one‐tenth of all living biota on Earth. Metabolic activity of the subseafloor microbes is generally extremely low due to low flux of nutrient and energy substrates in the habitats. However, the long‐term microbial activities play important ecological roles in biogeochemical cycles over geologic time scales. Most subseafloor bacteria and archaea are phylogenetically distinct from known isolates. Hence, the growth characteristics and metabolic activities of each species remain largely unknown.

Key concepts:

Significant microbial biomass is present in the deep subseafloor biosphere.

Metabolic activity of subseafloor microbes is extraordinary low.

Subseafloor microbes play important biogeochemical roles on geologic time scale.

Subseafloor microbial communities are mainly composed of uncultivated, hence uncharacterized components.

Ecologically significant microbial functions are expected from functional gene surveys and metagenomic analyses.

New analytical developments provide new insights into the nature of subseafloor life and the biosphere.
Nucleophile Phosphinidenkomplexe: Synthese und Anwendungen
Authors: Aktaş Halil , Slootweg J. Chris , Lammertsma Koop
Published: February 2010

Dieser Kurzaufsatz gibt einen Überblick über die Synthese, Eigenschaften und Reaktivitäten nucleophiler Phosphinidenkomplexe, [LnMPR]. Ein Schwerpunkt liegt auf Methoden zur Feinabstimmung der elektronischen Eigenschaften dieser neuen Klasse von Phosphorreagentien mithilfe verschiedener Hilfsliganden und koordinativ ungesättigter Übergangsmetallfragmente. Zudem richten wir unser Augenmerk auf die charakteristischen Unterschiede in der Anwendbarkeit der stabilen 18‐Elektronen‐Phosphinidene und der kurzlebigen 16‐Elektronen‐Phosphinidene.
Nucleophilic Phosphinidene Complexes: Access and Applicability
Authors: Aktaş Halil , Slootweg J. Chris , Lammertsma Koop
Published: February 2010

Syntheses, properties, and reactivities of nucleophilic phosphinidene complexes [LnMPR] are reviewed. Emphasis is placed on the electronic tuning of this emerging class of phosphorus reagents, using different ancillary ligands and coordinatively unsaturated transition‐metal moieties. The difference in applicability of the established stable 18‐electron and transient 16‐electron phosphinidenes is addressed.
Flame Atomic Absorption Spectrometry Determination of Trace Amounts of Cadmium and Zinc in Water Samples after Preconcentration onto Modified Amberlite XAD‐4 Resin
Authors: Mohammadi Sayed Zia , Afzali Daryoush , Taher Mohammad Ali , Darijani Hedayat
Published: February 2010

In the present article, a procedure for the simultaneous separation and preconcentration of trace amounts of cadmium and zinc is proposed. It is based on the adsorption of cadmium and zinc ions onto a column of Amberlite XAD‐4 resin loaded with aluminon reagent. Cadmium and zinc ions are quantitatively retained on the column in the pH range from 6.5–7.5, at a flow rate of 2 mL min–1. The cadmium and zinc ions are eluted with 5.0 mL of 5 mol L–1 HNO3 solution. Cadmium and zinc are measured by flame atomic absorption spectrometry (FAAS). In the present case, 0.1 μg of cadmium and 0.5 μg of zinc can be concentrated in the column from 1000 mL of aqueous sample, where their concentrations are as low as 0.1 and 0.5 ng mL–1, respectively. The relative standard deviations, for seven replicated determinations of 1.0 μg mL–1 of cadmium and zinc, are 1.2 and 1.1%, respectively. The detection limits for cadmium and zinc in the original solution are 0.02 and 0.11 ng mL–1, respectively. The interference of a large number of anions and cations has been studied and the optimized conditions are utilized for the determination of trace amounts of cadmium and zinc in different environmental and standard samples.
Nanostructured Carbon and Carbon Nanocomposites for Electrochemical Energy Storage Applications
Authors: Su Dang Sheng , Schlögl Robert
Published: February 2010

Electrochemical energy storage is one of the important technologies for a sustainable future of our society, in times of energy crisis. Lithium‐ion batteries and supercapacitors with their high energy or power densities, portability, and promising cycling life are the cores of future technologies. This Review describes some materials science aspects on nanocarbon‐based materials for these applications. Nanostructuring (decreasing dimensions) and nanoarchitecturing (combining or assembling several nanometer‐scale building blocks) are landmarks in the development of high‐performance electrodes for with long cycle lifes and high safety. Numerous works reviewed herein have shown higher performances for such electrodes, but mostly give diverse values that show no converging tendency towards future development. The lack of knowledge about interface processes and defect dynamics of electrodes, as well as the missing cooperation between material scientists, electrochemists, and battery engineers, are reasons for the currently widespread trial‐and‐error strategy of experiments. A concerted action between all of these disciplines is a prerequisite for the future development of electrochemical energy storage devices.
Building cost effective lower layer VPNs: The ILEC/CLEC dilemma
Authors: Meddeb Aref
Published: February 2010

Layer 2 and layer 1 Virtual Private Network (VPN) services; ranging from simple leased lines to extending private LANs across public networks, are commonplace today. With the continuously growing economic difficulties, capital meltdown, and telecommunication business turmoil, delivering those VPN services at the lowest cost or with the maximum revenue margin, while committing to Service Level Agreements (SLA), has become essential. We show that whether we tackle the optimal VPN design problem from an Incumbent Local Exchange Carrier (ILEC) standpoint or from a Competitive Local Exchange Carrier (CLEC) standpoint, we obtain contradictory rules. We show that by building Edge Disjoint VPN trees and spreading the traffic all over the network, the ILEC can achieve maximum throughput and enhanced network performance; while by concentrating all the VPN traffic over a single tree, the CLEC can minimize the cost of leased bandwidth. We then propose two simple algorithms that can help carriers and service providers leverage their networks and increase their revenue margins while meeting SLA requirements. Copyright © 2010 John Wiley & Sons, Ltd.
Synthetic Studies toward the CD Spiroketal of Spongistatins
Authors: Favre Sylvain , Gerber‐Lemaire Sandrine , Vogel Pierre
Published: February 2010

Starting from the readily availablemeso‐1,1′‐methylenebis(8‐oxabicyclo[3.2.1]oct‐6‐en‐3‐one) (1),meso‐1,1′‐methylenebis[(4R,4′S,6R,6′S)‐4,6‐dioxycyclohept‐1‐en‐1‐yl]tetrasilyl ethers7and8were obtained and transformed into all‐syn1,3,5,11,13,15‐hexahydroxypentadeca‐7,9‐dione derivatives9and10. The conversion of these intermediates into spiroketals was not successful. An alternative strategy based on thesequential and stereoselective functionalization of1afforded a 1‐(2,4,6,8‐tetrahydroxyoctyl)cyclohept‐1‐ene‐4,6‐diol derivative [(+)‐15, 94 %ee]. Ozonolysis of the cycloheptene moiety of (+)‐19provided the equatorial/axial spiroketal (+)‐21. Pivaloylation of its primary alcohol moiety and Meerwein methylation of the remaining secondary alcohol unit furnished (–)‐24, a potential precursor of the ketal isomer of the CD fragment found in spongistatins 1 and 2.
Effect of Lower‐Rim Alkylation of p‐Sulfonatocalix[4]arene on the Thermodynamics of Host–Guest Complexation
Authors: Cui Jie , Uzunova Vanya D. , Guo Dong‐Sheng , Wang Kui , Nau Werner M. , Liu Yu
Published: February 2010

The complex stability constants (KS) and thermodynamic parameters (ΔH° and TΔS°) for the 1:1 complexation of two water‐soluble calixarenes, p‐sulfonatocalix[4]arene (SC4A) and 5,11,17,23‐tetrasulfonato‐25,26,27,28‐tetrakis(n‐butyl)calix[4]arene (SC4A‐Bu), with organic ammonium cations and neutral spherical organic molecules, have been determined by means of isothermal titration calorimetry (ITC) in aqueous solutions at 298.15 K. The obtained results indicate that, upon complexation with these guests by SC4A‐Bu, the enthalpy changes become less favorable, whereas the entropy changes become more favorable relative to SC4A complexation. These differences can be attributed to differential degrees of desolvation and removal of high‐energy water as well as the change in conformation or conformational degrees of freedom upon complexation. The calorimetric investigations, accompanied by 1H NMR and UV/Vis spectroscopy and X‐ray crystallography provide a thermodynamic explanation for the different complexation behavior of SC4A and SC4A‐Bu towards charged and neutral organic guests. Binding ability and molecular selectivity are discussed from the viewpoint of the conformational geometry and electronic properties of hosts and guests.
Emotional support, negative interaction and DSM IV lifetime disorders among older African Americans: findings from the national survey of American life (NSAL)
Authors: Lincoln Karen D. , Taylor Robert Joseph , Bullard Kai McKeever , Chatters Linda M. , Woodward Amanda Toler , Himle Joseph A. , Jackson James S.
Published: February 2010

Objectives

Both emotional support and negative interaction with family members have been linked to mental health. However, few studies have examined the associations between emotional support and negative interaction and psychiatric disorders in late life. This study investigated the relationship between emotional support and negative interaction on lifetime prevalence of mood and anxiety disorders among older African Americans.

Design

The analyses utilized the National Survey of American Life.

Methods

Logistic regression and negative binomial regression analyses were used to examine the effect of emotional support and negative interaction with family members on the prevalence of lifetime DSM‐IV mood and anxiety disorders.

Participants

Data from 786 African Americans aged 55 years and older were used.

Measurement

The DSM‐IV World Mental Health Composite International Diagnostic Interview (WMH‐CIDI) was used to assess mental disorders. Three dependent variables were investigated: the prevalence of lifetime mood disorders, the prevalence of lifetime anxiety.

Results

Multivariate analysis found that emotional support was not associated with any of the three dependent variables. Negative interaction was significantly and positively associated with the odds of having a lifetime mood disorder, a lifetime anxiety disorder and the number of lifetime mood and anxiety disorders.

Conclusions

This is the first study to investigate the relationships among emotional support, negative interaction with family members and psychiatric disorders among older African Americans. Negative interaction was a risk factor for mood and anxiety disorders among older African Americans, whereas emotional support was not significant. Copyright © 2010 John Wiley & Sons, Ltd.
Arsenic adsorption on Ti‐pillared montmorillonite
Authors: Na Ping , Jia Xiumin , Yuan Bin , Li Yuan , Na Jiyu , Chen Yuchen , Wang Linshuang
Published: February 2010

BACKGROUND: Arsenic pollution in drinking water has been found in most countries. Arsenate (As(V)) and arsenite (As(III)) are two major forms of inorganic arsenic species, and the latter is the more toxic. The removal of arsenic ions from water has attracted increased attention, and therefore further understanding and development of techniques for removal of arsenic ions are required.

RESULTS: Adsorption of arsenate and arsenite from aqueous solutions using Ti‐pillared montmorillonite (Ti‐MMT) was investigated as a function of contact time, pH, temperature, coexisting ions, and ionic strength. The adsorption of both arsenate and arsenite were temperature and pH dependent, indicating different adsorption mechanisms. The effect of coexisting ions on the adsorption was also studied and, among the ions investigated, only phosphate had a noticeable influence on the adsorption of arsenate, while the effect of other ions was negligible. A pseudo‐second‐order chemical reaction model was obtained for both arsenate and arsenite; adsorption isotherms of arsenate and arsenite fitted the Langmuir and Freundlich isotherm models well. X‐ray diffraction (XRD) and X‐ray photoelectron spectroscopy (XPS) were used to study the nature of surface elements before and after adsorption.

CONCLUSIONS: This work demonstrates that Ti‐pillared montmorillonite is an efficient material for the removal of arsenate and arsenite from aqueous solutions. Experimental parameters such as contact time, solution pH, temperature, initial concentration, coexisting ions, and ionic strength have been optimized. Copyright © 2010 Society of Chemical Industry
The impact of ion pair association upon the 1H NMR spectra of cationic complexes akin to Grubbs catalysts
Authors: Schiemenz Günter Paulus
Published: February 2010

A reconsideration of the 1H NMR spectra of cationic transition metal complexes exhibiting the features of cyclophanes on the basis of Mislow's classification of topic groups arrives at the conclusion that the spectral changes triggered by chiral counterions reflect an intracationic diastereotopication of enantiotopic protons rather than the existence of pairs of long‐lived diastereomeric ion pairs. Copyright © 2010 John Wiley & Sons, Ltd.
Inaktive Kinasekonformationen stabilisieren
Authors: Rauh Daniel
Published: February 2010

Kinaseinhibitoren bekämpfen gezielt Krebs, der durch fehlregulierte Proteinkinasen entsteht. Außerdem dienen sie der chemischen Biologie als leistungsfähige Sondenmoleküle, um Proteinfunktionen auf zellulärer Ebene zu erforschen.
Zwischen molekularem Werkzeug und medizinischer Anwendung
Authors: Brodmann Tobias , Díaz Gómez Nina , Kalesse Markus
Published: February 2010

Myxobakterien produzieren eine Reihe potenziell nützlicher Naturstoffe für die medizinische Chemie, etwa die Chivosazole als Inhibitoren der Aktin‐Polymerisation oder Argyrine als Inhibitoren des Proteasoms.
NHC — Ligand der Ideen
Authors: Dröge Thomas , Glorius Frank
Published: February 2010

Die charakteristischen Eigenschaften von N‐heterocyclischen Carben‐Liganden sowie deren Quantifizierung und Variation eröffnen attraktive Möglichkeiten in der Katalyse.
Die Gehaltsumfrage läuft
Authors: Schmitz Karin
Published: February 2010

Der Fragebogen für GDCh‐Mitglieder in der Industrie kommt mit diesen Nachrichten aus der Chemie.
Mehr Verfahrenseffizienz in der pharmazeutischen Industrie
Authors: Jablonsky Catherine , Schofield Russell
Published: February 2010

Die Software Aspenone koordiniert in Forschung und Entwicklung getrennte Gruppen, die am selben Projekt arbeiten. Sie bindet die Prozessentwicklung in die Unternehmensabläufe ein und unterstützt Verfahren wie automatische Chargenfreigaben oder Prozessanalysen.
Emissionen aus Polymeren messen
Authors: Reingruber Eva , Reussner Jens , Sauer Christian , Standler Alexander , Buchberger Wolfgang
Published: February 2010

Ob sich ein Kunststoff für eine Anwendung, etwa im Innenraum eines Autos, eignet, hängt auch davon ab, welche Substanzen er ausgast. Diese Emissionen lassen sich gaschromatographisch analysieren. Dafür eignen sich die statische Headspace‐ und die Thermodesorptions‐Gaschromatographie.
Evaluation of lufenuron as a chemosterilant against fruit flies of the genus Anastrepha (Diptera: Tephritidae)
Authors: Moya Pilar , Flores Salvador , Ayala Ildefonso , Sanchis Juan , Montoya Pablo , Primo Jaime
Published: February 2010

BACKGROUND: Chemosterilisation with lufenuron bait stations is a recently developed technique that is being implemented for Ceratitis capitata Wiedemann control. The aim of this work was to evaluate the chemosterilising effect of lufenuron against four economically important Latin American fruit flies species: Anastrepha ludens (Loew.), A. obliqua Macquart, A. serpentina Wiedemann and A. striata Schiner (Diptera: Tephritidae) in order to design a similar strategy for their control.

RESULTS: Sexually mature adults were treated by ingestion with concentrations ranging from 0.1 to 30.0 mg g−1 of lufenuron in the diet. In addition, conspecific crosses with only one of the sexes being treated (30.0 mg g−1) were performed in order to appraise the contribution of each sex to the sterilising effect. In all cases, fecundity was not affected by the treatments, as opposed to fertility where all Anastrepha species studied were significantly affected, although to different extents. The conspecific crosses showed that treated males of A. ludens, A. obliqua and A. serpentina were not able to transmit the sterility to their respective untreated females. Only in the case of A. striata did crossing treated males with untreated females significantly reduced egg hatch.

CONCLUSION: Although further investigations are required, the present results demonstrate that the use of lufenuron for controlling A. striata could be potentially viable. Copyright © 2010 Society of Chemical Industry
Superconductor–insulator transition in two dimensions for neutral disorder
Authors: Gold A.
Published: February 2010

We describe the superconductor–insulator transition in thin films via the model of a disorder Bose‐condensate (dirty boson model). Coulomb interaction due to charged carriers and a random potential described by a strength and a range (Gaussian disorder) are taken into account. Analytical and numerical results are presented for the transition point of the quantum‐phase transition in terms a microscopic model for the disorder. We compare with experimental results. Some comments are made concerning a two‐fluid model. The corresponding phase‐transition diagram is discussed.
Band structures of CeRu2(Si1−xGex)2 studied by resonant soft X‐ray ARPES
Authors: Okane Tetsuo , Ohkochi Takuo , Takeda Yukiharu , Fujimori Shin‐ichi , Yasui Akira , Saitoh Yuji , Yamagami Hiroshi , Fujimori Atsushi , Matsumoto Yuji , Sugi Motoki , Kimura Noriaki , Komatsubara Takemi , Aoki Haruyoshi
Published: February 2010

Angle‐resolved photoelectron spectroscopy (ARPES) measurements were made in the Ce $3d \to 4f$ resonance energy region for the paramagnetic state of CeRu2Si2, CeRu2(Si0.82Ge0.18)2, and LaRu2Si2 to investigate a variation of band structures around the quantum critical point (QCP). The observed band structures are very similar between CeRu2Si2 and CeRu2(Si0.82Ge0.18)2. The results indicate that the Ce 4f electrons in the paramagnetic state have an itinerant character and participate in the formation of energy bands both in CeRu2Si2 and CeRu2(Si0.82Ge0.18)2, and the change of the band structures in the paramagnetic states should be continuous around the QCP of the CeRu2(Si1−xGex)2 system.
Factors that influence the accuracy of adolescent proxy reporting of parental characteristics: A research note
Authors: Ridolfo Heather , Maitland Aaron
Published: February 2010

Socioeconomic status (SES) is considered to be an important marker of physical, mental, and social outcomes. However, methods used to gather socioeconomic information vary widely in terms of both the indicators of SES used (e.g., education, occupation, income, etc.) and data collection strategies. In particular, studies of adolescents often rely on children's proxy reports of measures of parents' SES. There is disagreement in the literature regarding children's ability to reliably serve as proxy respondents for their parents. Using data from the National Longitudinal Study of Adolescent Health, a nationally representative sample of adolescents and their parents, we assess the accuracy of children's proxy reports of mothers' education and receipt of public assistance. Results show that accuracy of children's proxy reports varies by children's age, gender, and race; however, social class largely accounts for race differences found.
Controllability of a string submitted to unilateral constraint
Authors: Ammar-Khodja Farid , Micu Sorin , Münch Arnaud
Published: February 2010

This article studies the controllability property of a homogeneous linear string of length one, submitted to a time dependent obstacle (described by the function

\{\psi (t)\}_{0⩽t⩽T}

) located below the extremity

x = 1

. The Dirichlet control acts on the other extremity

x = 0

. The string is modelled by the wave equation

y''−y_{xx} = 0

in

(t,x) \in (0,T) \times (0,1)

, while the obstacle is represented by the Signorini's conditions

y(t,1)⩾\psi (t)

,

y_{x}(t,1)⩾0

,

y_{x}(t,1)(y(t,1)−\psi (t)) = 0

in

(0,T)

. The characteristic method and a fixed point argument allow to reduce the problem to the analysis of the solutions at

x = 1

. We prove that, for any

T > 2

and initial data

(y^{0},y^{1}) \in H^{1}(0,1) \times L^{2}(0,1)

with

\psi (0)⩽y^{0}(1)

, the system is null controllable with controls in

H^{1}(0,T)

. Two distinct approaches are used. We first introduce a penalized system in

y_{\epsilon }

, transforming the Signorini's condition into the simpler one

y_{\epsilon ,x}(t,1) = \epsilon ^{−1}[y_{\epsilon }(t,1)−\psi (t)]^{−}

,

ϵ

being a small positive parameter. We construct explicitly a family of controls of the penalized problem, uniformly bounded with respect to

ϵ

in

H^{1}(0,T)

. This enables us to pass to the limit and to obtain a control for the initial equation. A more direct approach, based on differential inequalities theory, leads to a similar positive conclusion. Numerical experiments complete the study.

Cet article étudie les propriétés de contrôlabilité d'une corde homogène de longeur un, soumise à un obstacle dépendant du temps (décrit par la fonction

\{\psi (t)\}_{0⩽t⩽T}

) à l'extrémité

x = 1

. Le contrôle Dirichlet agit à l'extrémité

x = 0

. La corde est modélisée par l'équation des ondes

y''−y_{xx} = 0

dans

(t,x) \in (0,T) \times (0,1)

, tandis que l'obstacle est représenté par les conditions de Signorini

y(t,1)⩾\psi (t)

,

y_{x}(t,1)⩾0

,

y_{x}(t,1)(y(t,1)−\psi (t)) = 0

sur

(0,T)

. La méthode des caractéristiques et un argument de point fixe permettent de réduire le problème à l'analyse des solutions en

x = 1

. Nous prouvons que, pour tout

T > 2

et donnée initiale

(y^{0},y^{1}) \in H^{1}(0,1) \times L^{2}(0,1)

avec

\psi (0)⩽y^{0}(1)

, le système est contrôlable à zéro avec des contrôles dans

H^{1}(0,T)

. Deux approches sont utilisées. On introduit tout d'abord un système pénalisé en

y_{\epsilon }

, transformant les conditions de Signorini en l'égalité

y_{\epsilon ,x}(t,1) = \epsilon ^{−1}[y_{\epsilon }(t,1)−\psi (t)]^{−}

,

ϵ

étant un paramètre positif. On construit explicitement une famille de contrôle du problème pénalisé uniformément bornée par rapport à

ϵ

dans

H^{1}(0,T)

. Cela nous permet de passer à la limite et d'obtenir un contrôle pour le système initial. Une approche plus directe, relevant de la théorie des inéquations différentielles, conduit à un résultat positif similaire. Quelques applications numériques complètent l'étude.
GABAA receptor subunit β1 is involved in the formation of protease‐resistant prion protein in prion‐infected neuroblastoma cells
Authors: Kimura Tomohiro , Ishikawa Kensuke , Sakasegawa Yuji , Teruya Kenta , Sata Tetsutaro , Schätzl Hermann , Doh-ura Katsumi
Published: February 2010

γ‐Aminobutyric acid type A (GABAA) receptor β1 (gabrb1), a subunit of GABAA receptors involved in inhibitory effects on neurotransmission, was found to associate with the formation of protease‐resistant prion protein in prion‐infected neuroblastoma cells. Silencing of gabrb1 gene expression significantly decreased the abnormal prion protein level but paradoxically increased the normal prion protein level. Treatment with a gabrb1‐specific inhibitor, salicylidene salicylhydrazide, dose‐dependently decreased the abnormal prion protein level, but silencing of other GABAA receptor subunits’ gene expression and treatments with the receptor antagonists and agonists did not. Therefore, gabrb1 involvement in abnormal prion protein formation is independent of GABAA receptors.
Regulation of ceramide channels by Bcl‐2 family proteins
Authors: Ganesan Vidyaramanan , Colombini Marco
Published: February 2010

Mitochondrial outer membrane permeabilization to proteins, an irreversible step in apoptosis by which critical proteins are released, is tightly regulated by Bcl‐2 family proteins. The exact nature of the release pathway is still undefined. Ceramide is an important sphingolipid, involved in various cellular processes including apoptosis. Here we describe the structural properties of ceramide channels and their regulation by the anti‐apoptotic and pro‐apoptotic proteins of the Bcl‐2 family. The evolutionarily conserved regulation of ceramide channels by Bcl‐2 family proteins, consistent with their role in apoptosis, lends credibility to the notion that ceramide channels constitute the protein release pathway.
Evaluation of the anti-endotoxin effects of polymyxin B in a feline model of endotoxemia
Authors: Sharp Claire R. , DeClue Amy E. , Haak Carol E. , Honaker Allison R. , Reinero Carol R.
Published: February 2010

Directed, effective therapies for feline sepsis are needed to reduce the high morbidity and mortality associated with this disease. We investigated the anti-endotoxin effects of polymyxin B (PMB) in a blinded, placebo controlled fashion, both ex vivo in a feline whole blood culture system and in vivo, using a low-dose endotoxin infusion in cats. Serial measures of systemic inflammation, and hemodynamic stability, were compared between groups. Ex vivo, PMB significantly decreased lipopolysaccharide-induced tumor necrosis factor (TNF) production from whole blood. PMB (1 mg/kg over 30 min) demonstrated anti-endotoxin effects in vivo, including decreased peak plasma TNF activity ( P<0.001) and increased white blood cell count ( P=0.019), with no adverse effects. Given the apparent safety and anti-endotoxin effects of PMB in this endotoxemia model, a carefully designed, randomized, blinded, placebo controlled clinical trial evaluating the use of PMB in naturally occurring Gram-negative feline sepsis should be considered.
COI sequencing as tool for the taxonomic attribution ofPatellaspp. (Gastropoda): the case of morphologically undistinguishable juveniles settled on aPatella ferrugineaadult
Authors: Casu Marco , Sanna Daria , Cristo Benedetto , Lai Tiziana , Dedola Gian Luca , Curini-Galletti Marco
Published: February 2010

Patella ferrugineais an endangered marine gastropod, distributed on the western Mediterranean coasts, whose range has progressively contracted, due to intense human exploitation. A genetic analysis was performed on two unidentified young individuals belonging to the genusPatellafound attached to the shell of an adult ofP. ferruginea, with a twofold aim: (i) to achieve their correct taxonomic attribution by means of the DNA barcoding; and (ii) to shed some light on the hypothesized larval philopatry and/or juveniles phoresis inP. ferruginea. The survey was carried out comparing the sequences of the cytochrome c oxidase subunit I (COI) Folmer region obtained for the two juveniles with those obtained for adults ofP. ferruginea, P. caerulea, P. rustica, andP. ulyssiponensis, from different sites of the western Mediterranean, by means of maximum likelihood cluster analysis and a Bayesian-based assignment test. Results obtained evidenced that: (i) COI may be used with confidence as DNA barcoding in the genusPatella; and (ii) the two juveniles studied are not conspecific: one belonged toP. ferruginea, the other toP. rustica.The latter finding raises doubts about the juvenile phoresis and about the occurrence of larval philopatry inP. ferruginea, suggesting that an extensive use of a molecular approach for a better evaluation of the recruitment features of this endangered species should be adopted.
Applying predator-prey theory to modelling immune-mediated, within-host interspecific parasite interactions
Authors: FENTON ANDY , PERKINS SARAH E.
Published: February 2010

Predator-prey models are often applied to the interactions between host immunity and parasite growth. A key component of these models is the immune system's functional response, the relationship between immune activity and parasite load. Typically, models assume a simple, linear functional response. However, based on the mechanistic interactions between parasites and immunity we argue that alternative forms are more likely, resulting in very different predictions, ranging from parasite exclusion to chronic infection. By extending this framework to consider multiple infections we show that combinations of parasites eliciting different functional responses greatly affect community stability. Indeed, some parasites may stabilize other species that would be unstable if infecting alone. Therefore hosts' immune systems may have adapted to tolerate certain parasites, rather than clear them and risk erratic parasite dynamics. We urge for more detailed empirical information relating immune activity to parasite load to enable better predictions of the dynamic consequences of immune-mediated interspecific interactions within parasite communities.
Biogeochemical zonation due to intrameander hyporheic flow
Authors: Boano F. , Demaria A. , Revelli R. , Ridolfi L.
Published: February 2010

The dynamics of chemicals within a catchment are strongly affected by the exchange between surface water and groundwater. The activity of hyporheic microorganisms plays a key role in these processes, as they are able to oxidize and reduce organic matter and nutrients. The interplay between the residence times in the hyporheic zone and the temporal scales of the microbial reactions must thus be understood in order to improve our understanding of the role of fluvial environments in nutrient cycling. In this paper we focus on the intrameander hyporheic region and investigate the links between river morphology, hyporheic flow field, and biogeochemical processes. We adopt a modeling framework that considers the planimetric evolution of a meandering river, the hyporheic flow field induced by the river sinuosity, and the main biogeochemical reactions of organic carbon degradation. The chemical zonation of the intrameander hyporheic zone clearly emerges as a result of the coupling between hyporheic flow and biochemical activity. The resulting patterns of nutrient concentrations are strongly influenced by the river morphology. We also show how to estimate the characteristic timescales of the redox reactions and that their interplay with the kinematic timescales of the hyporheic flow controls both the biochemical zonation and the overall rate of nutrient transformation.
Ocean temperature and salinity inverted from combined hydrographic and seismic data
Authors: Papenberg C. , Klaeschen D. , Krahmann G. , Hobbs R. W.
Published: February 2010

Recently seismic reflection methods have been successfully applied to oceanographic issues. Here, we present a new approach, combining XBT and CTD surveys with seismic observations, to visualize long sections with a resolution down to a few meters. The challenge to a full investigation of mixing processes has been the tremendous span of spatial scales ranging from hundreds of kilometers to centimeters. Traditional hydrographic observations could only resolve the large scale effects by measuring temperature and salinity profiles at discrete locations typically several kilometers apart, whereas dedicated localized measurements allowed investigation of the ocean fine structure at the other end of the spatial spectrum. The intermediate scales have in contrast been difficult to observe systematically. Here we present temperature and salinity data inverted from seismic observations that cover the intermediate scales and provide a new approach to image mesoscale processes and allow the investigation of their dynamics at unprecedented resolution.
Effects of the dipole tilt and northward and duskward IMF on dayside magnetic reconnection in a global MHD simulation
Authors: Park K. S. , Ogino T. , Kim Y. H.
Published: February 2010

By using a three‐dimensional global magnetohydrodynamic simulation of the Earth's magnetosphere, we have studied whether antiparallel or subsolar reconnection better describes magnetospheric dynamics at the dayside magnetopause for the case of northward and duskward interplanetary magnetic field (IMF) and a positive dipole tilt. The simulation shows that the reconnection dominantly occurs at high latitudes where antiparallel field regions appear in the northern dusk sector and in the southern dawn sector. For the northward and duskward IMF case of 30° dipole tilt, the reconnection region in the dusk sector moves tailward at high magnetic latitudes in the Northern Hemisphere along the magnetopause further than that for the southward IMF case. Both the convective electric field and the resistive electric field are peaked in the region where the field lines are antiparallel. Moreover the perpendicular and parallel components of the current in the antiparallel field region are greater than those of the current in the subsolar and magnetic equator regions. The field‐aligned current, in the Southern (winter) Hemisphere on the dawn region is stronger than that in the Northern (summer) Hemisphere on the dusk region because the reconnection site shifts toward the tail in the winter hemisphere, which is just opposite to the case of southward IMF studied by Park et al. (2006). In the Northern (summer) Hemisphere, a three‐cell pattern appears in the ionosphere because the reconnection site shifts tailward and duskward from the cusp. In the Southern (winter) Hemisphere, the three‐cell pattern is distorted and has a weaker cross‐polar cap potential than that in the Northern Hemisphere due to the effects of the positive dipole tilt.
Diffusion of NOx and HONO in snow: A laboratory study
Authors: Pinzer B. R. , Kerbrat M. , Huthwelker T. , Gäggeler H. W. , Schneebeli M. , Ammann M.
Published: February 2010

The diffusion of trace gases in snow and firn is a crucial process for snow‐atmosphere interactions and air mixing in firn. It is very sensitive to interactions of the trace gas with the ice surface. We developed an experimental setup to measure the effective diffusion constant of nitrogen oxides (NOx = NO + NO2) and the highly soluble nitrous acid (HONO). The method combines X‐ray microtomography and a radioactive tracer technique: tomography provides the microscopic configuration of the pore space as well as the amount of ice surface accessible for the gas, while radioactively labeled molecules reveal the dynamics of diffusion. Bringing together the precise characterization of snow microstructure and the dynamics of tracer diffusion, the partitioning between gas phase and ice can be studied. We present results measured in two different snow types, fresh snow and aged, rounded snow. The fast diffusion of NO and NO2 was measured by analyzing the temporal evolution of their gas phase concentration downstream of the snow samples. The effective diffusivity of HONO could be directly measured from the steady state migration profiles of radioactively labeled HO13NO molecules. The measured effective diffusion constants of NO and NO2 agree well with the theory of diffusion in porous media. This underlines that tomography may be used to map diffusivity in snow or firn with high spatial resolution. Owing to the interactions of HONO with ice, the effective diffusion constant of HONO was 2 to 3 orders of magnitude smaller than the diffusivity in air.
Ion‐mediated nucleation in the atmosphere: Key controlling parameters, implications, and look‐up table
Authors: Yu Fangqun
Published: February 2010

Nucleation is an important source of atmospheric particles and ubiquitous ions in the atmosphere have long been known to promote nucleation. An ion‐mediated nucleation (IMN) mechanism based on a kinetic model is supported by recent measurements of the excess charge on freshly nucleated particles and ion cluster evolution during nucleation events. Here we investigate the dependence of steady state IMN rate (JIMN) on key controlling parameters. We find that sulfuric acid vapor concentration, temperature, relative humidity, ionization rate, and surface area of preexisting particles have profound and nonlinear impacts on JIMN. The sensitivities of JIMN to the changes in these key parameters may imply important physical feedback mechanisms involving climate and emission changes, solar variations, nucleation, aerosol number abundance, and aerosol indirect radiative forcing. We also describe a five‐dimensional JIMN look‐up table derived from the most recent version of the IMN model, with the key parameters covering a wide range of atmospheric conditions. With the look‐up table and a multiple‐variable interpolation subroutine, JIMN and the properties of critical clusters can be determined efficiently and accurately under given atmospheric conditions. The look‐up table reduces the computational costs of the IMN rate calculations significantly (by a factor of around 8000) and can be readily incorporated into multidimensional models to study the secondary particle formation via IMN and associated climatic and health effects.
A perchlorate brine lubricated deformable bed facilitating flow of the north polar cap of Mars: Possible mechanism for water table recharging
Authors: Fisher David A. , Hecht Michael H. , Kounaves Samuel P. , Catling David C.
Published: February 2010

The Phoenix Wet Chemistry Lab (WCL) discovered substantial amounts of magnesium, calcium, and sodium perchlorate in the soil of polar Mars. Magnesium perchlorate is likely the dominant salt in the polar region's soils. But it could be that the cations are contributed by a mixture of Mg, Ca, and Na. Mg, Ca, and Na perchlorate brines can stay liquid as low as ∼−69, −74, −32°C, respectively. WCL reports 0.7 % (wt) of the soil is pure perchlorate, and if 5% of the northern permanent ice cap is soil, then the perchlorate could make about 1/2800 of the ice cap. This suggests there could be enough perchlorate in the ice cap to generate about 1–3 m of brine at the bed. Large areas under the north polar cap have basal temperatures above −69°C so the Mg and Ca perchlorate brines would be liquid. Because of its high density, the perchlorate brine would pool over impervious layers and make the bed into a perchlorate sludge, which could be mobilized and deformed by the weight of the overburden of ice and soil. The sludge would be deformed and moved outward and stop where the basal temperature dropped below −69°C. During the warmest climates, any frozen cold dam at the edge could be breached and the brine reintroduced to the polar surface. Some of the brine could have penetrated downward under the ice cap. This mobile sludge‐bed ice cap has been modeled with a 2‐D time‐varying model. Results of such model runs have similarities to measured layers found by shallow subsurface radar.
Organometallics in Environment and Toxicology
Authors: Thayer John S , Jenkins Richard O , Harrington Chris F , Ragsdale Stephen W , Dey Mishtu , Gajda Tamas , Abadin Henry G , Pohl Hana R , Reimer Kenneth J , Dopp Elke , Kligerman Andrew D , Diaz-Bone Roland A , Filella Montserrat , Wallschlager Dirk , Feldmann Jorg , Hintelmann Holger , Hirner Alfred V , Rettenmeier Albert V , Kraeutler Bernhard , Matthews Rowena G , Thauer Rudolf K , Lindahl Paul A , Camps Juan C Fontecilla , Peters John W , Brunold Thomas , Rivera Mario , Karlin Kenneth D , Sosa-Torres Martha E , Hille Russ
Published: February 2010

This title is not available to purchase from Royal Society of Chemistry. Please visit www.bioinorganic-chemistry.org/mils for title information.

 

This volume, closely related to MILS-6, deals mainly with metal(loid)-alkyl derivatives but also with the rarer aryl compounds. Most of these (commonly toxic) compounds are formed in the environment by microorganisms, but some anthropogenic input occurs as well. MILS-7, providing a most up-to-date view, is of special relevance for researchers in analytical and bioinorganic chemistry, enzymology, environmental chemistry, physiology, toxicology, and related medical fields.
Analysis of Organometal(loid) Compounds in Environmental and Biological Samples
Authors: Harrington Christopher F. , Vidler Daniel S. , Jenkins Richard O.
Published: February 2010

Measurement of the different physicochemical forms of metals and metalloids is a necessary pre-requisite for the detailed understanding of an element's interaction with environmental and biological systems. Such chemical speciation data is important in a range of areas, including toxicology, ecotoxicology, biogeochemistry, food safety and nutrition. This chapter considers developments in the speciation analysis of organometallic compounds (OMCs), focusing on those of As, Hg, Se and Sn. Typically, organometallic analysis requires a chromatographic separation prior to analyte detection and gas chromatography (GC), high performance liquid chromatography (HPLC) or capillary electrophoresis (CE) can serve this purpose. Following separation, detection is achieved using element specific detectors (ESDs) such as inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma optical emission spectroscopy (ICP-OES), atomic fluorescence spectrometry (AFS), atomic absorption spectrometry (AAS) or atmospheric pressure ionization mass spectrometry (API-MS). Techniques employing a vapor generation (VG) stage prior to detection are also discussed. Complementary structural and quantitative data may be acquired through the combination of elemental and molecular mass spectrometry. The advantages and disadvantages of the various analytical systems are discussed, together with issues related to quantification and quality management.
Alkyllead Compounds and Their Environmental Toxicology
Authors: Abadin Henry G. , Pohl Hana R.
Published: February 2010

Alkyllead compounds are man-made compounds in which a carbon atom of one or more organic molecules is bound to a lead atom. Tetraethyllead and tetramethyllead are the most common alkyllead compounds that were used primarily as gasoline additives for many years. Consequently, auto emissions have accounted for a major part of lead environmental pollution. Alkyllead compounds can readily enter living organisms as they are well absorbed via all major routes of entry. Because of their lipid solubility, the alkylleads can also readily cross the blood-brain barrier. The toxicokinetic information on organic lead can be used as biomarkers of exposure for monitoring exposed individuals. The organic alkyllead compounds are more toxic than the inorganic forms of lead. Neurotoxicity is the predominant effect of lead (both for organic and inorganic forms), although lead affects almost every organ of the body. The use of alkyllead compounds has declined over the last 20 years, due to the worldwide effort to eliminate the use of leaded gasoline. This achievement can be viewed as a great accomplishment of public health preventive measures.
Organoarsenicals. Uptake, Metabolism, and Toxicity
Authors: Dopp Elke , Kligerman Andrew D. , Diaz-Bone Roland A.
Published: February 2010

Arsenic is categorized by the WHO as the most significant environmental contaminant of drinking water due to the prevalence of geogenic contamination of groundwaters. Arsenic and the compounds which it forms are considered to be carcinogenic. The mechanism of toxicity and in particular of carcinogenicity of arsenic is still not well understood. The complexity originates from the fact that arsenic can form a rich variety of species, which show a wide variability in their toxicological behavior. The process of biomethylation was for many years regarded as a detoxification process; however, more recent research has indicated that the reverse is in fact the case. In this book chapter we give a summary of the current state of knowledge on the toxicities and toxicological mechanisms of organoarsenic species in order to evaluate the role and significance of these regarding their adverse effects on human health.
Environmental Bioindication, Biomonitoring, and Bioremediation of Organometal(loid)s
Authors: Thayer John S.
Published: February 2010

Environmentally occurring organometal(loid)s have generated some severe health and safety problems. Consequently, scientists have been investigating various organisms to show the presence of such compounds (bioindicators), to follow their movement through the environment (biomonitors), and to remove them (bioremediators). Examples of such organisms and the mechanisms of their action(s) are discussed. Also mentioned are those organisms that form organometal(loid)s as a way of removing toxic inorganic species.
'Show me the money': financial incentives increase chlamydia screening rates among tertiary students: a pilot study
Authors: Currie Marian J. , Schmidt Matthias , Davis Belinda K. , Baynes Anne M. , O'Keefe Elissa J. , Bavinton Tim P. , McNiven Michelle , Martin Sarah J. , Bowden Francis J.
Published: February 2010

Background: We hypothesise that text-messaging and financial incentives would increase tertiary student participation in chlamydia screening. Methods: A cross-sectional study was conducted over two phases on eight tertiary campuses during 2007. During Phase 1 (6 months) study activities were advertised through student organisations and media. Education and screening were offered during a range of student activities. During Phase 2 (4 days) education and screening were offered via text messages. Non-financial incentives were offered during Phase 1 and a $10 cash incentive was offered during Phase 2. Rates of specimens provided by students and the direct costs incurred during each phase were compared. Results: 2786 students attended the 31 activities conducted in Phase 1. Of these, 627 students (22.5%) provided urine specimens for chlamydia testing. During Phase 2, the dissemination of 866 text messages resulted in urine specimens from 392 students (45.3%). Costs per test were AUD $175.11 in Phase 1 and AUD $27.13 in Phase 2. Conclusions: Compared with more labour intensive (and therefore more expensive) screening activities conducted over a 6-month period, offering a small financial incentive to tertiary students through text messaging over a 4-day period significantly increased participation in on-campus chlamydia screening. This model could readily be applied to other populations to increase participation in chlamydia screening.