bluuebunny/crossref_metadata_2025 huggingface dataset:
Physiological effects of free fatty acid production in genetically engineered Synechococcus elongatus PCC 7942
Authors: Ruffing Anne M. , Jones Howland D.T.
Published: April 2012

The direct conversion of carbon dioxide into biofuels by photosynthetic microorganisms is a promising alternative energy solution. In this study, a model cyanobacterium, Synechococcus elongatus PCC 7942, is engineered to produce free fatty acids (FFA), potential biodiesel precursors, via gene knockout of the FFA‐recycling acyl‐ACP synthetase and expression of a thioesterase for release of the FFA. Similar to previous efforts, the engineered strains produce and excrete FFA, but the yields are too low for large‐scale production. While other efforts have applied additional metabolic engineering strategies in an attempt to boost FFA production, we focus on characterizing the engineered strains to identify the physiological effects that limit cell growth and FFA synthesis. The strains engineered for FFA‐production show reduced photosynthetic yields, chlorophyll‐a degradation, and changes in the cellular localization of the light‐harvesting pigments, phycocyanin and allophycocyanin. Possible causes of these physiological effects are also identified. The addition of exogenous linolenic acid, a polyunsaturated FFA, to cultures of S. elongatus 7942 yielded a physiological response similar to that observed in the FFA‐producing strains with only one notable difference. In addition, the lipid constituents of the cell and thylakoid membranes in the FFA‐producing strains show changes in both the relative amounts of lipid components and the degree of saturation of the fatty acid side chains. These changes in lipid composition may affect membrane integrity and structure, the binding and diffusion of phycobilisomes, and the activity of membrane‐bound enzymes including those involved in photosynthesis. Thus, the toxicity of unsaturated FFA and changes in membrane composition may be responsible for the physiological effects observed in FFA‐producing S. elongatus 7942. These issues must be addressed to enable the high yields of FFA synthesis necessary for large‐scale biofuel production. Biotechnol. Bioeng. 2012;109: 2190–2199. © 2012 Wiley Periodicals, Inc.
Measurement of solar spectra relating to photosynthesis and solar cells: An inquiry lab for secondary science
Authors: Ruggirello Rachel M. , Balcerzak Phyllis , May Victoria L. , Blankenship Robert E.
Published: April 2012

The process of photosynthesis is central to science curriculum at all levels. This article describes an inquiry‐based laboratory investigation developed to explore the impact of light quality on photosynthesis and to connect this process to current research on harvesting solar energy, including bioenergy, artificial photosynthesis, and solar cells. This laboratory was used with high‐school science teachers who then took this experience back to their classrooms. During this exercise, teachers used an economical spectroradiometer to measure the solar spectrum and relate this to photosynthetic light absorption by determining the quality of light beneath trees. Following this investigation, teachers learned about the plant‐inspired dye‐sensitized solar cells and constructed one. To connect their light quality investigation to the efficiency of photosynthesis and solar cells, teachers then collected data at locations with varying quality and intensity of light. In sum, this investigation provides a crucial connection between photosynthesis and cutting edge research on solar energy technologies. Our learning experience provides a new instructional model for understanding a little investigated aspect of photosynthesis and connects to authentic scientific research.
Interactive educational tool for compensators design in MATLAB® using frequency response analysis
Authors: Ramirez‐Cortes Juan Manuel , Alarcon‐Aquino Vicente , Gomez‐Gil Pilar , Diaz‐Mendez Alejandro , Ibarra‐Bonilla Mariana , García‐Enriquez Irma
Published: April 2012

This article presents an educational platform developed to support the teaching of compensators design in a basic control theory course. The application consists of a graphical user interface in MATLAB®, and further connection to the plant under study through the data acquisition toolbox, and a data acquisition card. The developed system allows the students to experiment with parameter changes in the controllers under study, such as gain, overshoot, settling time, and peak time, and visualize results obtained from simulated or real signals. The methodology is based on the frequency response analysis. Typical Bode, root locus, and unit step response plots are easily obtained for a system before and after compensation, in a dynamical way. A modular design allows the students to easily upgrade the application in order to include further methodologies. Results derived from its use in undergraduate and graduate courses are presented. MATLAB is a registered trademark of The MathWorks, Inc.© 2012 Wiley Periodicals, Inc. Comput Appl Eng Educ 22:699–707, 2014; View this article online at wileyonlinelibrary.com/journal/cae; DOI 10.1002/cae.21562
A New Application Area for Ag‐NHCs: CO2 Fixation Catalyst
Authors: Taşcı Zeynep , Kunduracıoğlu Ahmet , Kani İbrahim , Çetinkaya Bekir
Published: April 2012

The first example of the silver‐NHC catalyzed cycloaddition of CO2 to terminal epoxides is reported. The choice of NHC substituents, halides and the nature of additives were determined to be important. Ionic [(Cnmim)2Ag]2[Ag2Br4] (Cnmim=1‐(CnH2n+1)‐3‐methylimidazol‐2‐ylidene; n=4–18) catalysts exhibited a high yield of styrene carbonate (77–92 %) in the presence of 4‐dimethylaminopyridine (DMAP) as a cocatalyst without needing any solvent. The catalytic activity improved as the length of the alkyl groups (n) increased, although substituents longer than C14 did not produce any further beneficial effect. For the protocol performed at 1.5 MPa pressure and 100 °C the TOF was calculated to be 440 h−1. A prolonged reaction time and increased pressure of CO2 increased the yield. Used without any additive, compound C14 was able to fix CO2 with PO (propylene oxide) quantitatively at 120 °C, 2.0 MPa and could be used at least seven times without loss of activity and selectivity. The nucleophilic nature of the anion is decisive for the formation of the product.
On the Stability of Pulse‐Jet Regenerated‐Bag Filter Operation
Authors: Saleem M. , Krammer G.
Published: April 2012

Problems with the pulse‐jet bag filter operation have a direct influence on process plant operation and may result in loss of production time. Therefore, long‐term stable operation of the plant is desirable for both the manufacturers and operators. The effects of operating parameters are studied experimentally on filter operation with regeneration between the upper and lower pressure drop limits. Many combinations were identified when the filter operation derailed from stable to unstable operation on changing one of the operating parameters. Filtration velocity, pulse pressure, and the upper limit of pressure drop had the potential of creating instability. A threshold detachment overpressure existed below which the operation led to unstable conditions at a certain filtration velocity and which increased with increasing velocity.
Gold(I) Styrylbenzene, Distyrylbenzene, and Distyrylnaphthalene Complexes: High Emission Quantum Yields at Room Temperature
Authors: Gao Lei , Niedzwiecki Daniel S. , Deligonul Nihal , Zeller Matthias , Hunter Allen D. , Gray Thomas G.
Published: April 2012

One gold(I)‐substituted styrylbenzene, six digold(I) distyrylbenzenes, one tetragold distyrylbenzene, and four digold distyrylnaphthalene complexes were synthesized using base‐promoted auration, alkynylation, triazolate formation, and Horner–Wadsworth–Emmons reactions. The gold(I) fragments are either σ‐bonded to the aromatic system, or they are attached through an alkynyl or triazolate spacer. Product formation was monitored using 31P{1H} NMR spectroscopy. Systems in which gold(I) binds to the central benzene ring or the terminal phenyl rings were designed. All of these complexes have strong ultraviolet absorptions and emit blue light. The position of the gold(I) attachment influences the luminescence efficiency. Complexes with two gold(I) fragments attached to the ends of the conjugated system have fluorescence quantum yields up to 0.94, when using 7‐diethylamino‐4‐methylcoumarin as the emission standard. Density‐functional theory calculations on three high‐yielding emitters suggest that luminescence originates from the distyrylbenzene or ‐naphthalene bridge.
4‐(N,N‐Dimethylamino)pyridine‐Embedded Nanoporous Conjugated Polymer as a Highly Active Heterogeneous Organocatalyst
Authors: Zhang Yuan , Zhang Yong , Sun Ya Lei , Du Xin , Shi Jiao Yi , Wang Wei David , Wang Wei
Published: April 2012

We report herein for the first time the incorporation of a versatile organocatalyst, 4‐(N,N‐dimethylamino)pyridine (DMAP), into the network of a nanoporous conjugated polymer (NCP) by the “bottom‐up” approach. The resulting DMAP‐NCP material possesses highly concentrated and homogeneously distributed DMAP catalytic sites (2.02 mmol g−1). DMAP‐NCP also exhibits enhanced stability and permanent porosity due to the strong covalent linkage and the rigidity of the “bottom‐up” monomers. As a result, DMAP‐NCP shows excellent catalytic activity in the acylation of alcohols with yields of 92–99 %. The DMAP‐NCP catalyst could be easily recovered from the reaction mixture and reused in at least 14 consecutive cycles without measurable loss of activity. Moreover, the catalytic acylation reaction could be performed under neat and continuous‐flow conditions for at least 536 h of continuous work with the same catalyst activity.
The Reaction of Sulfenic Acids with Peroxyl Radicals: Insights into the Radical‐Trapping Antioxidant Activity of Plant‐Derived Thiosulfinates
Authors: Amorati Riccardo , Lynett Philip T. , Valgimigli Luca , Pratt Derek A.
Published: April 2012

Sulfenic acids play a prominent role in biology as key participants in cellular signaling relating to redox homeostasis, in the formation of protein‐disulfide linkages, and as the central players in the fascinating organosulfur chemistry of the Allium species (e.g., garlic). Despite their relevance, direct measurements of their reaction kinetics have proven difficult owing to their high reactivity. Herein, we describe the results of hydrocarbon autoxidations inhibited by the persistent 9‐triptycenesulfenic acid, which yields a second order rate constant of 3.0×106 M−1 s−1 for its reaction with peroxyl radicals in PhCl at 30 °C. This rate constant drops 19‐fold in CH3CN, and is subject to a significant primary deuterium kinetic isotope effect, kH/kD=6.1, supporting a formal H‐atom transfer (HAT) mechanism. Analogous autoxidations inhibited by the Allium‐derived (S)‐benzyl phenylmethanethiosulfinate and a corresponding deuterium‐labeled derivative unequivocally demonstrate the role of sulfenic acids in the radical‐trapping antioxidant activity of thiosulfinates, through the rate‐determining Cope elimination of phenylmethanesulfenic acid (kH/kD≈4.5) and its subsequent formal HAT reaction with peroxyl radicals (kH/kD≈3.5). The rate constant that we derived from these experiments for the reaction of phenylmethanesulfenic acid with peroxyl radicals was 2.8×107 M−1 s−1; a value 10‐fold larger than that we measured for the reaction of 9‐triptycenesulfenic acid with peroxyl radicals. We propose that whereas phenylmethanesulfenic acid can adopt the optimal syn geometry for a 5‐centre proton‐coupled electron‐transfer reaction with a peroxyl radical, the 9‐triptycenesulfenic is too sterically hindered, and undergoes the reaction instead through the less‐energetically favorable anti geometry, which is reminiscent of a conventional HAT.
Synthesis of Planar Chiral Iridacycles by Cationic Metal π‐Coordination: Facial Selectivity, and Conformational and Stereochemical Consequences
Authors: Djukic Jean‐Pierre , Iali Wissam , Pfeffer Michel , Le Goff Xavier‐Frédéric
Published: April 2012

Facial selectivity during the π‐coordination of pseudo‐tetrahedral iridacycles by neutral (Cr(CO)3), monocationic (Cp*Ru+), and biscationic (Cp*Ir2+) metal centers was directly influenced by the coulombic imbalance in the coordination sphere of the chelated Ir center. We also showed by using theoretical calculations that the feasibility of the related metallacycles that displayed metallocenic planar chirality was dependent to the presence of an electron‐donating group, such as NMe2, which contributed to the overall stability of the complexes. When the π‐bonded moiety was the strongly electron‐withdrawing Cp*Ir2+ group, the electron donation from NMe2 resulted in major conformational changes, with a barrier to rotation of about 17 kcal mol−1 for this group that became spectroscopically diastereotopic (high‐field 1H NMR spectroscopy). This peculiar property is proposed as a means to introduce a new type of constitutional chirality at the nitrogen center: planar chirality at tertiary aromatic amines.
Nickel‐Mediated Inter‐ and Intramolecular Reductive Cross‐Coupling of Unactivated Alkyl Bromides and Aryl Iodides at Room Temperature
Authors: Yan Chang‐Song , Peng Yu , Xu Xiao‐Bo , Wang Ya‐Wen
Published: April 2012

A nickel‐mediated intermolecular reductive cross‐coupling reaction of unactivated alkyl bromides and aryl iodides at room temperature has been developed and successfully extended to less explored intramolecular versions and tandem cyclization‐intermolecular cross‐coupling. Highly stereoselective (or stereospecific) synthesis of linear‐fused perhydrofuro[2,3‐b]furan (pyran) and spiroketal skeletons allows rapid access to these useful building blocks, which would be potentially valuable in the synthesis of relevant natural products. A rational explanation for the formation of contiguous stereogenic centers is given.
Nickel(II) and Copper(II) Complexes of β‐Unsubstituted 5,15‐Diazaporphyrins and Pyridazine‐Fused Diazacorrinoids: Metal–Template Syntheses and Peripheral Functionalizations
Authors: Matano Yoshihiro , Shibano Tarou , Nakano Haruyuki , Imahori Hiroshi
Published: April 2012

The present paper reports the first comprehensive study on the synthesis, structures, optical and electrochemical properties, and peripheral functionalizations of nickel(II) and copper(II) complexes of β‐unsubstituted 5,15‐diazaporphyrins (M‐DAP; M=Ni, Cu) and pyridazine‐fused diazacorrinoids (Ni‐DACX; X=N, O). These two classes of compounds were constructed starting from mesityldipyrromethane by a metal–template method. Ni‐DAP and Cu‐DAP were prepared in high yields by the reaction of the respective metal–bis(dibromodipyrrin) complexes with NaN3–CuX (X=I, Br), whereas Ni‐DACN and Ni‐DACO were formed as predominant products by the reaction with NaN3. In both cases, the metal centers change their geometry from tetrahedral to square planar during the aza‐annulation; X‐ray crystallographic analyses of M‐DAPs showed highly planar diazaporphyrin π planes. The Q band of Ni‐DAP was redshifted and intensified compared with that of a nickel–porphyrin reference, due to the involvement of electronegative nitrogen atoms at the meso positions. It was found that the peripheral bromination of Ni‐DAP and Ni‐DACO occurred regioselectively to afford Ni‐DAP‐Br4 and Ni‐DACO‐Br, respectively. These brominated derivatives underwent Stille reactions with tributyl(phenyl)stannane to give the corresponding phenylated derivatives, Ni‐DAP‐Ph4 and Ni‐DACO‐Ph. On the basis of the absorption spectra and X‐ray analysis, it has been concluded that the attached phenyl groups efficiently conjugate with the diazaporphyrin π system. The present results unambiguously corroborate that the β‐unsubstituted DAPs and DACXs are promising platforms for the development of a new class of π‐conjugated azaporphyrin‐based materials.
Water‐soluble/dispersible carbazole‐containing random and block copolymers by nitroxide‐mediated radical polymerisation
Authors: Lessard Benoît H. , Marić Milan
Published: April 2012

A series of carbazole‐containing water‐dispersible poly(acrylic acid)‐b‐(9‐(4‐vinylbenzyl)‐9H‐carbazole) block copolymers (poly(AA)‐b‐poly(VBK)) and water‐soluble poly(methacrylic acid‐ran‐(9‐(4‐vinylbenzyl)‐9H‐carbazole)) (poly(MAA‐ran‐VBK)) random copolymers were synthesised in a controlled manner (i.e. low polydispersities $(\overline {M_{{\rm w}} } /\overline {M_{n} } < 1.3)$ by nitroxide‐mediated polymerisation (NMP) using an SG1‐based alkoxyamine initiator, BlocBuilder. Poly(AA)‐b‐poly(VBK) block copolymers were most easily accessed by using poly(AA) in its protected form as the macroinitiator for the 9‐(4‐vinylbenzyl)‐9H‐carbazole (VBK) block. Controlled polymerisation of MAA was accomplished using an excess of 10 mol.% SG1 relative to BlocBuilder with VBK as controlling co‐monomer (initial molar feed content fVBK,0 = 0.03–0.20) in dimethylformamide at 80°C. Poly(MAA‐ran‐VBK) copolymers with a final VBK molar composition of FVBK < 0.30 resulted in water‐soluble copolymers. In addition, as macroinitiators, poly(MAA‐ran‐VBK)s were sufficiently pseudo‐living to reinitiate a second batch of monomer (90 mol.% methyl methacrylate with styrene) in organic solvent and by ab initio, surfactant‐free emulsion polymerisation. In both cases, low polydispersity, amphiphilic block copolymers resulted $(\overline {M_{{\rm w}} } /\overline {M_{{\rm n}} } < 1.3)$. © 2012 Canadian Society for Chemical Engineering
Testing uniformity for the case of a planar unknown support
Authors: Berrendero José R. , Cuevas Antonio , Pateiro‐López Beatriz
Published: April 2012

A new test is proposed for the hypothesis of uniformity on bi‐dimensional supports. The procedure is an adaptation of the “distance to boundary test” (DB test) proposed in Berrendero, Cuevas, & Vázquez‐Grande (2006). This new version of the DB test, called DBU test, allows us (as a novel, interesting feature) to deal with the case where the support S of the underlying distribution is unknown. This means that S is not specified in the null hypothesis so that, in fact, we test the null hypothesis that the underlying distribution is uniform on some support S belonging to a given class ${\cal C}$. We pay special attention to the case that ${\cal C}$ is either the class of compact convex supports or the (broader) class of compact λ‐convex supports (also called r‐convex or α‐convex in the literature). The basic idea is to apply the DB test in a sort of plug‐in version, where the support S is approximated by using methods of set estimation. The DBU method is analysed from both the theoretical and practical point of view, via some asymptotic results and a simulation study, respectively. The Canadian Journal of Statistics 40: 378–395; 2012 © 2012 Statistical Society of Canada
Lesion‐induced generation of interneuron cell types in specific dorsoventral domains in the spinal cord of adult zebrafish
Authors: Kuscha Veronika , Frazer Sarah L. , Dias Tatyana B. , Hibi Masahiko , Becker Thomas , Becker Catherina G.
Published: April 2012

In contrast to mammals, adult zebrafish regenerate neurons in the lesioned spinal cord. For example, motor neurons are generated from an olig2‐expressing population of pMN‐like ependymoradial glial cells in a ventrolateral position at the central canal. However, the extent of neuronal regeneration is unclear. Here we show, using a transgenic fish in which V2 interneurons are labeled by green fluorescent protein (GFP) under the control of the vsx1 promoter, that after a complete spinal cord transection, large numbers of V2 interneurons are generated in the vicinity of the lesion site. Tg(vsx1:GFP)+ cells are not present in the unlesioned spinal cord and label with the proliferation marker bromodeoxyuridine (BrdU) after a lesion. Some mediolaterally elongated Tg(vsx1:GFP)+ cells contact the central canal in a medial position. These cells likely arise from a p2‐like domain of ependymoradial glial progenitor cells, indicated by coexpression of Pax6 and Nkx6.1, but not DsRed driven by the olig2 promoter in these cells. We also present evidence that Pax2+ interneurons are newly generated after a spinal lesion, whereas the generation rate for a dorsal population of parvalbuminergic interneurons is comparatively low. Our results identify the regenerative potential of different interneuron types for the first time and support a model in which different progenitor cell domains in distinct dorsoventral positions around the central canal are activated by a lesion to give rise to diverse neuronal cell types in the adult zebrafish spinal cord. J. Comp. Neurol. 520:3604–3616, 2012. © 2012 Wiley Periodicals, Inc.
Neuronal populations in the basolateral nuclei of the amygdala are differentially increased in humans compared with apes: A stereological study
Authors: Barger Nicole , Stefanacci Lisa , Schumann Cynthia M. , Sherwood Chet C. , Annese Jacopo , Allman John M. , Buckwalter Joseph A. , Hof Patrick R. , Semendeferi Katerina
Published: April 2012

In human and nonhuman primates, the amygdala is known to play critical roles in emotional and social behavior. Anatomically, individual amygdaloid nuclei are connected with many neural systems that are either differentially expanded or conserved over the course of primate evolution. To address amygdala evolution in humans and our closest living relatives, the apes, we used design‐based stereological methods to obtain neuron counts for the amygdala and each of four major amygdaloid nuclei (the lateral, basal, accessory basal, and central nuclei) in humans, all great ape species, lesser apes, and one monkey species. Our goal was to determine whether there were significant differences in the number or percent of neurons distributed to individual nuclei among species. Additionally, regression analyses were performed on independent contrast data to determine whether any individual species deviated from allometric trends. There were two major findings. In humans, the lateral nucleus contained the highest number of neurons in the amygdala, whereas in apes the basal nucleus contained the highest number of neurons. Additionally, the human lateral nucleus contained 59% more neurons than predicted by allometric regressions on nonhuman primate data. Based on the largest sample ever analyzed in a comparative study of the hominoid amygdala, our findings suggest that an emphasis on the lateral nucleus is the main characteristic of amygdala specialization over the course of human evolution. J. Comp. Neurol. 520:3035–3054, 2012. © 2012 Wiley Periodicals, Inc.
Single‐Crystal X‐Ray Diffraction, Isolated‐Molecule and Cluster Electronic Structure Calculations, and Scanning Electron Microscopy in an Organic solid: Models for Intramolecular Motion in 4,4′‐Dimethoxybiphenyl
Authors: Wang Xianlong , Rotkina Lolita , Su Hong , Beckmann Peter A.
Published: April 2012

This paper brings together field emission scanning electron microscopy, single‐crystal X‐ray diffraction, and density functional electronic structure calculations in both an isolated molecule and a cluster of seven whole and fourteen half molecules of 4,4′‐dimethoxybiphenyl to investigate coupled methyl‐group rotation (over a barrier) and methoxy‐group libration (meaning a rotation from the ground state not all the way to the transition state and back again). The structure of the isolated molecule, determined by the electronic structure calculations, is compared with the structure of the molecule found in the crystal. As the methyl group rotates from its ground state to its transition state, the methoxy group rotates 30° in the isolated molecule and 16° in the cluster. The calculated barriers for this coupled methyl‐group rotation and methoxy group libration in the isolated molecule and in the crystal are 12.8 kJ mol−1 and 10.3 kJ mol−1 respectively, suggesting that intermolecular interactions in the crystal lower the barrier. These barriers are compared with the value of 11.5±0.5 kJ mol−1 obtained from solid‐state 1H spin‐lattice relaxation measurements [P. A. Beckmann and E. Schneider, J. Chem. Phys. 2012, 136, 054508.]
Interpersonal Psychotherapy for Postpartum Depression
Authors: Stuart Scott
Published: April 2012

Perinatal depression is prevalent and has a great impact on both mother and infant. There are empirically validated treatments for both postpartum depression and depression during pregnancy. Primary among these is Interpersonal Psychotherapy, which has been shown to be effective for postpartum women across the spectrum from mild to severe depression. At present, Interpersonal Psychotherapy is the best validated treatment for postpartum depression and should be considered first‐line treatment, especially for depressed breastfeeding women. Copyright © 2012 John Wiley & Sons, Ltd.

Key Practitioner Message

IPT is a first‐line evidence‐based treatment for postpartum depression.

IPT can be easily modified for postpartum depression.

Partners can be included in IPT for postpartum depression.

Group IPT for postpartum depression is effective for depression.
Nonlinear behavioural model of charge pump PLLs
Authors: Brambilla Angelo , Linaro Daniele , Storace Marco
Published: April 2012

Despite the nonlinear nature of even the simplest versions of phase locked loops (PLLs), linear models are still used during the first phases of the design of modern PLLs. Even though the linear model may represent a crude approach, its use is justified by the fact that accurate numerical simulations often require a too large amount of CPU time, being PLLs by construction stiff circuits, characterised by very different time scales. This aspect has triggered the need for compact models that allow fast and accurate numerical simulations. The scientific literature numbers several models that have been developed with different approaches and tailored to different simulation environments. In this context, we propose a nonlinear model of a type‐II PLL, which (1) considers both the switching behaviour of the phase/frequency detector and charge pump and the complex dynamics (including the presence of amplitude and phase noise) of the voltage controlled oscillator, (2) is compact and can be easily implemented in modern mixed analog/digital simulators as a behavioural block, and (3) allows the simulation of spurs owing to the nonlinearities of both the charge pump and the fractional frequency divider. Copyright © 2012 John Wiley & Sons, Ltd.
Development and laboratory‐scale testing of a fully automated online flow cytometer for drinking water analysis
Authors: Hammes Frederik , Broger Tobias , Weilenmann Hans‐Ulrich , Vital Marius , Helbing Jakob , Bosshart Ulrich , Huber Pascal , Peter Odermatt Res , Sonnleitner Bernhard
Published: April 2012

Accurate and sensitive online detection tools would benefit both fundamental research and practical applications in aquatic microbiology. Here, we describe the development and testing of an online flow cytometer (FCM), with a specific use foreseen in the field of drinking water microbiology. The system incorporated fully automated sampling and fluorescent labeling of bacterial nucleic acids with analysis at 5‐min intervals for periods in excess of 24 h. The laboratory scale testing showed sensitive detection (< 5% error) of bacteria over a broad concentration range (1 × 103–1 × 106 cells mL−1) and particularly the ability to track both gradual changes and dramatic events in water samples. The system was tested with bacterial pure cultures as well as indigenous microbial communities from natural water samples. Moreover, we demonstrated the possibility of using either a single fluorescent dye (e.g., SYBR Green I) or a combination of two dyes (SYBR Green I and Propidium Iodide), thus broadening the application possibilities of the system. The online FCM approach described herein has considerable potential for routine and continuous monitoring of drinking water, optimization of specific drinking water processes such as biofiltration or disinfection, as well as aquatic microbiology research in general. © 2012 International Society for Advancement of Cytometry
Intelligent route generation: discovery and search of correlation between shared resources
Authors: Yen Neil Y. , Huang Runhe , Ma Jianhua , Jin Qun , Shih Timothy K.
Published: April 2012

Sharing information and resources on the Internet has become an important activity for education. The use of ubiquitous devices makes it possible for learning participants to be engaged in an open and connected social environment, and also allows the learning activities to be performed at any time and any place. In this study, the discovery of correlation among shared resources is concentrated. A hypothetical scenario is considered that the information, such as photos and thoughts, is applicable to be shared with implicit context (i.e., geographical information) by learners through a practical implementation, PadSCORM, on a mobile device. Two major contributions are achieved. First, the correlations among resources are determined through usage experiences mining and geographical information adjustment. It then assists learners in filtering out redundant information by highlighting the significance of resources. Second, an intelligent searching algorithm is proposed to visualize adaptive routes to facilitate search process and to enrich the learning activity. The empirical experiments revealing the feasibility and performance (e.g., accuracy and effectiveness) are conducted in the universities in North Taiwan. Copyright © 2012 John Wiley & Sons, Ltd.
An authenticated group key distribution protocol based on the generalized Chinese remainder theorem
Authors: Guo Cheng , Chang Chin‐Chen
Published: April 2012

The group key distribution protocol is a mechanism for distributing a group key that is used to encrypt the communication data transmitted in an open group. Recently, a novel group key distribution protocol based on secret sharing was proposed. In their protocol, the group key information is broadcast in an open network environment, and only authorized group members can obtain the group key. However, their protocol requires each group member to broadcast a random challenge to the rest of the group members in the construction of the group key, and this may increase communication cost and cause network traffic congestion. In this paper, we propose an authenticated group key distribution protocol based on the generalized Chinese remainder theorem that drastically reduces communication costs while maintaining at least the same degree of security. Our protocol is built on the secret sharing scheme based on Chinese remainder theorem, which requires fewer computation operations than the previous work. Copyright © 2012 John Wiley & Sons, Ltd.
The Ly6 neurotoxin‐like molecule target of wit regulates spontaneous neurotransmitter release at the developing neuromuscular junction in Drosophila
Authors: Kim Nam Chul , Marqués Guillermo
Published: April 2012

Refinement of neural circuits during development requires formation and elimination of synaptic connections, a process governed by activity‐dependent mechanisms and developmental genetic programs. Bone Morphogenetic Protein (BMP) retrograde signaling through the type II receptor Wishful thinking (Wit) is essential for synaptic growth and functional development of the Drosophila larval neuromuscular junction. However, little is known about the genes that are regulated by the pathway to effect synaptic growth and proper synaptic transmission. We have identified a transcriptional target of wit (twit), whose expression in motoneurons depends on Wit activity. Null twit mutants are viable and fertile, but recapitulate some of the electrophysiological phenotypes of wit mutants, such as decreased frequency and amplitude of miniature excitatory junction potentials. Other wit phenotypes, such as decreased synaptic terminal size and evoked excitatory junction potentials, are not found in twit mutants, suggesting that homeostatic compensation of presynaptic release is intact in twit mutants and that Wit regulates additional genes to accomplish proper synaptic maturation. Twit is a glycosylphosphatidylinositol‐anchored protein of the Lymphocyte antigen 6 family (Ly‐6), and neuronal expression of a twit transgene rescues twit's mutant phenotypes. Importantly, twit expression partially rescues diminished frequency of miniature excitatory synaptic potentials in wit mutants. This further supports the conclusions that Twit is signaling in larval motoneurons and an essential effector of the retrograde BMP signal. Taken together, our results suggest that retrograde BMP signaling regulates spontaneous neurotransmitter release by activating the transcription of the Ly‐6 gene twit. © 2011 Wiley Periodicals, Inc. Develop Neurobiol, 2012
Genetic mouse models for skin research: Strategies and resources
Authors: Schneider Marlon R.
Published: April 2012

A number of features contributed to establishing the mouse as the favorite model organism for skin research: the genetic and pathophysiological similarities to humans, the small size and relatively short reproductive period, meaning low maintenance costs, and the availability of sophisticated tools for manipulating the genome, gametes, and embryos. While initial studies depended on strains displaying skin abnormalities due to spontaneous genetic mutations, the availability of the transgenic and knockout technologies and their astonishing perfection during the last decades allowed the development of mouse lines permitting any imaginable genetic modification including gene inactivation, substitution, modification, or overexpression. While these technologies have already contributed to the functional analysis of several genes and processes related to skin research, continued progress requires understanding, awareness, and access to these mouse resources. This review will identify the strategies currently employed for the genetic manipulation of mice in skin research, and outline current resources and their limitations. genesis 50:652–664, 2012. © 2012 Wiley Periodicals, Inc.
New Routes to Soluble Magnesium Amidoborane Complexes
Authors: Jones Cameron , Bonyhady Simon J. , Nembenna Sharanappa , Stasch Andreas
Published: April 2012

Several new synthetic routes to the known and new magnesium amidoborane complexes, [{(Nacnac)Mg(NH2BH3)}2] and [(Nacnac)Mg(NH2BH3)(THF)] (Nacnac = DipNacnac, [{N(Dip)C(Me)}2CH]–, or tBuNacnac, [{N(Dip)C(tBu)}2CH]–; Dip = C6H3iPr2‐2,6), are reported. These include the reductive dehydrogenation reaction of NH3BH3 (AB) with the magnesium(I) dimer, [{(DipNacnac)Mg}2], and the salt elimination reaction of [(DipNacnac)MgI(OEt2)] with Li(NH2BH3). Moreover, the reaction of ammonia–borane with two magnesium(II) hydride complexes, [{(Nacnac)Mg(μ‐H)}2], or an alkylmagnesium(II) complex [{(DipNacnac)Mg(μ‐nBu)}2], have been shown to yield well defined parent amidoborane complexes of magnesium for the first time. The crystal structures of all prepared complexes were obtained and shown to be similar to those previously reported for related compounds.
Cholesterol photosensitized oxidation in muscle foods
Authors: Boselli Emanuele , Cardenia Vladimiro , Rodriguez‐Estrada Maria Teresa
Published: April 2012

Cholesterol photoxidation can affect the nutritional quality of fresh meat and fish due to the formation of cholesterol oxidation products (COPs), which exert a strong impact on the lipid metabolism and are involved in various chronic and degenerative diseases and disturbance of cell functionality. The evaluation of light sensitized cholesterol oxidation has been reviewed in beef, pork, horse, turkey, and sardine muscle. In the retail market, fresh slices of meat or fish are usually displayed in refrigerated vessels wrapped with plastic film and are exposed to a fluorescent light. Under these conditions, COPs can range from 8.5 µg/g of lipids (photoxidized pork meat) to more than 300 µg/g of lipids (photoxidized horse meat), corresponding to a maximum of 1.3% of oxidized cholesterol. The oxidative process can be reduced by feeding the animals with antioxidants, such as tocopherols, or by spraying the muscle food with lipid‐ or water‐soluble antioxidants before packaging. However, the combined use of alternative protective packaging and lighting conditions during commercial retail storage, such as the use of red wrapping films, warm tone lamps, and modified atmosphere with low oxygen content, can efficiently prevent photoxidation without modifying the food product composition and sensory properties.
Sensitive and Selective Sensing of Hydrogen Peroxide with Iron‐Tetrasulfophthalocyanine‐Graphene‐Nafion Modified Screen‐Printed Electrode
Authors: Zhu Mingfang , Li Nan , Ye Jianshan
Published: April 2012

We developed a novel iron‐tetrasulfophthalocyanine‐graphene‐Nafion (FeTSPc‐GR‐Nafion) modified screen‐printed electrode to determine hydrogen peroxide (H2O2) with high sensitivity and selectivity. The nanocomposite film (FeTSPc‐GR‐Nafion) exhibits an excellent electrocatalytic activity towards oxidation of H2O2 at a potential of +0.35 V in the absence of enzyme. A comparative study reveals that the FeTSPc‐GR complexes play a dual amplification role. Amperometric experiment indicates that the sensors possess good sensitivity and selectivity, with a linear range from 2.0×10−7 M to 5.0×10−3 M and a detection limit of 8.0×10−8 M. This sensor has been successfully used to develop the glucose biosensor and has also been applied to determine H2O2 in sterile water.
Model‐based predicting and correcting algorithms for substructure online hybrid tests
Authors: Wang Tao , Cheng Chun , Guo Xun
Published: April 2012

A set of algorithms combined with a substructure technique is proposed for an online hybrid test framework, in which the substructures are encapsulated by a standard interface that implements displacements and forces at the common substructure boundaries. A coordinator equipped with the proposed algorithms is designed to achieve boundary compatibility and equilibrium, thereby endowing the substructures the ability to behave as one piece. A model‐based predictor and corrector, and a noniterative procedure, characterize the set of algorithms. The coordinator solves the dynamics of the entire structure and updates the static boundary state simultaneously by a quasi‐Newton procedure, which gradually formulates the condensed stiffness matrix associated with corresponding degrees of freedom. With the condensed stiffness matrix and dynamic information, a condensed equation of motion is derived and then solved by a typical time integration algorithm. Three strategies for updating the condensed stiffness matrix are incorporated into the proposed algorithms. Each adopts different stiffness matrix during the predicting and correcting stage. These algorithms are validated by two numerical substructure simulations and a hybrid test. The effectiveness and feasibility are fully demonstrated. Copyright © 2012 John Wiley & Sons, Ltd.
Quantifying the anthropogenic fraction of fatty alcohols in a terrestrial environment
Authors: Mudge Stephen M. , DeLeo Paul C. , Dyer Scott D.
Published: April 2012

Fatty alcohols are naturally produced hydrocarbons present in all living organisms. They are also used in detergent and cosmetic formulations, may be sourced from either petroleum or biological materials, and are typically disposed of down the drain. This study was conducted on the Luray catchment, Virginia, USA, where sales data indicate that approximately 2 kg of fatty alcohols from detergent enter the wastewater every day. Reconstructing fatty alcohols in the influent on the basis of sales data indicated a mix of odd and even chain compounds, with C12 being dominant. This profile was influenced strongly by liquid laundry detergents (69%). Sediment and soil samples from the catchment were analyzed by gas chromatography–mass spectrometry and by stable isotope ratio mass spectrometry to determine the δ13C and δ2H signatures. The long-chain components in agricultural soils and river sediments were distinguishable clearly from the algal fatty alcohols produced within the river system. The wastewater was a mixture of fecal and detergent sources of fatty alcohols in a ratio of 75:25%. The fatty alcohols in the effluent had different stable isotopic signatures and chain-length profiles from the influent, indicating that these compounds are not the same as those that entered the treatment plant. The total quantity of fatty alcohols leaving the treatment plant through the effluent pipe was low compared with the input. Analysis of the contributions based on the stable isotopes and profiles suggests that of the fatty alcohols present in the river system downstream of the treatment plant, 84% were derived from terrestrial plant production, 15% came from in situ algal synthesis, and 1% were derived from the effluent. Environ. Toxicol. Chem. 2012;31:1209–1222. © 2012 SETAC
Assessment of hormonal activities and genotoxicity of industrial effluents using in vitro bioassays combined with chemical analysis
Authors: Fang Yi-Xiang , Ying Guang-Guo , Zhao Jian-Liang , Chen Feng , Liu Shan , Zhang Li-Juan , Yang Bin
Published: April 2012

Wastewaters from various industries are a main source of the contaminants in aquatic environments. The authors evaluated the hormonal activities (estrogenic/anti-estrogenic activities, androgenic/anti-androgenic activities) and genotoxicity of various effluents from textile and dyeing plants, electronic and electroplate factories, pulp and paper mills, fine chemical factories, and municipal wastewater treatment plants in the Pearl River Delta region by using in vitro bioassays (yeast estrogen screen [YES]; yeast androgen screen [YAS]; and genotoxicity assay [umu/SOS]) combined with chemical analysis. The results demonstrated the presence of estrogenic, anti-estrogenic, and anti-androgenic activity in most industrial effluents, whereas no androgenic activities were detected in all of the effluents. The measured estrogenic activities expressed as estradiol equivalent concentrations (EEQs) ranged from below detection (3 of 26 samples) to 40.7 ng/L, with a mean of 7.33 ng/L in all effluents. A good linear relationship was found between the EEQs measured by YES bioassay and the EEQs calculated from chemical concentrations. These detected estrogenic compounds, such as 4-nonylphenol and estrone, were responsible for the estrogenic activities in the effluents. The genotoxic effects expressed as benzo[a]pyrene equivalent concentrations (BaP EQs) varied between below detection and 88.2 µg/L, with a mean of 8.76 µg/L in all effluents. The target polycyclic aromatic hydrocarbons were minor contributors to the genotoxicity in the effluents, and some nontarget compounds in the effluents were responsible for the measured genotoxicity. In terms of estrogenic activities and genotoxicity, discharge of these effluents could pose high risks to aquatic organisms in the receiving environments. Environ. Toxicol. Chem. 2012;31:1273–1282. © 2012 SETAC
Decreased metal accumulation in passerines as a result of reduced emissions
Authors: Berglund Åsa M.M. , Rainio Miia J. , Eeva Tapio
Published: April 2012

Technological advances in industrial processes have resulted in reduced atmospheric emissions from metal industries all over the globe, but the response of the environment is not well known. The authors studied metal (As, Cd, Cu, Ni, Pb, and Se) accumulation in passerine birds (pied flycatcher, Ficedula hypoleuca, and great tit, Parus major) following almost 20 years of reduced metal emissions from the largest nonferrous smelter in Finland. Close to the industry, emission reductions resulted in reduced exposure to several of the elements and, more importantly, reduced accumulation by 58 to 95% in liver tissue. Albeit showing significant tissue reductions, nestlings had elevated concentrations of arsenic, cadmium, lead, and selenium close to the industry. Single-element concentrations were below critical levels associated with subclinical effects, but the mixture of toxic elements indirectly affected health and reproduction. Our study indicates that in environments with moderate duration of industrial activity, impact, and soil pollution, metal accumulation in organisms can decrease relatively rapidly when atmospheric emissions are reduced. Environ. Toxicol. Chem. 2012;31:1317–1323. © 2012 SETAC
Exposure to the pesticide linuron affects androgen-dependent gene expression in the three-spined stickleback (Gasterosteus aculeatus)
Authors: Hogan Natacha S. , Gallant Melanie J. , van den Heuvel Michael R.
Published: April 2012

Previous research demonstrated that exposure to exogenous androgens and effluents with androgenic activity can induce spiggin mRNA production in the kidney of the three-spined stickleback (Gasterosteus aculeatus). In the present study, we determine whether a short-term exposure to a known antiandrogenic pesticide, linuron (LN), suppresses spiggin mRNA in male stickleback and in androgenized female stickleback. Primers were designed from previously characterized sequences for each androgen receptor (AR) isoform in stickleback, arα and arβ, to assess whether these receptors are differentially regulated by androgen or antiandrogen exposure. Fish were exposed for 72 h to one of four treatments: control, LN (250 µg/L), 17α-methyltestosterone (MT, 500 ng/L), and an LN–MT mixture at those same concentrations. There was no effect of LN on spiggin and arβ mRNA levels in male kidney, while levels of arα were significantly increased twofold. Exposure to LN significantly inhibited MT-induced spiggin RNA production in female kidney with no effect on expression of arα and arβ. The present study is the first to demonstrate the antiandrogenic effect of LN at the transcript level and to examine androgenic/antiandrogenic responsiveness of the two ARs in the stickleback. From the present study, it was determined that measurement of spiggin RNA is a reliable and sensitive screening tool for the detection of both androgenic and antiandrogenic compounds. Environ. Toxicol. Chem. 2012;31:1391–1395. © 2012 SETAC
Hepatitis B virus X protein stabilizes amplified in breast cancer 1 protein and cooperates with it to promote human hepatocellular carcinoma cell invasiveness
Authors: Liu Yonghong , Tong Zhangwei , Li Ting , Chen Qiang , Zhuo Luting , Li Wengang , Wu Ray-Chang , Yu Chundong
Published: April 2012

Chronic infection of hepatitis B virus (HBV) is closely associated with the development of human hepatocellular carcinoma (HCC). HBV X protein (HBx) plays a key role in the progression of HCC. We recently found that amplified in breast cancer 1 (AIB1) protein is overexpressed in 68% of human HCC specimens and promotes HCC progression by enhancing cell proliferation and invasiveness. Given that both HBx and AIB1 play important oncogenic roles in HCC, we aimed to determine whether they could cooperatively promote human HCC development. Herein, we show that HBx-positive HCC tissues had a higher level of AIB1 protein, compared to HBx-negative HCC tissues. A positive correlation between HBx protein level and AIB1 protein level was established in HCC specimens. Without affecting its messenger RNA level, HBx induced a significant increase of the protein level of AIB1, which correlated with a significant extension of the half-life of AIB1 protein. Mechanistically, HBx could interact with AIB1 to prevent the interaction between envelope protein 3 ubiquitin ligase F-box and WD repeat domain containing 7 (Fbw7)α and AIB1, then inhibited the Fbw7α-mediated ubiquitination and degradation of AIB1. In addition, reporter assays and chromatin immunoprecipitation assays revealed that both HBx and AIB1 were recruited to matrix metalloproteinase-9 (
MMP-9
) promoter to enhance

MMP-9

promoter activity cooperatively. Consistently, HBx and AIB1 cooperatively enhanced

MMP-9

expression in HepG2 cells, which, in turn, increased cell-invasive ability.

Conclusion:

Our study demonstrates that HBx can stabilize AIB1 protein and cooperate with it to promote human HCC cell invasiveness, highlighting the essential role of the cross-talk between HBx and AIB1 in HBV-related HCC progression.