bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of pressure on decoupling of ionic conductivity from structural relaxation in hydrated protic ionic liquid, lidocaine HCl
Authors: Swiety-Pospiech A. , Wojnarowska Z. , Hensel-Bielowka S. , Pionteck J. , Paluch M.
Published: May 2013

Broadband dielectric spectroscopy and pressure-temperature-volume methods are employed to investigate the effect of hydrostatic pressure on the conductivity relaxation time (τσ), both in the supercooled and glassy states of protic ionic liquid lidocaine hydrochloride monohydrate. Due to the decoupling between the ion conductivity and structural dynamics, the characteristic change in behavior of τσ(T) dependence, i.e., from Vogel-Fulcher-Tammann-like to Arrhenius-like behavior, is observed. This crossover is a manifestation of the liquid-glass transition of lidocaine HCl. The similar pattern of behavior was also found for pressure dependent isothermal measurements. However, in this case the transition from one simple volume activated law to another was noticed. Additionally, by analyzing the changes of conductivity relaxation times during isothermal densification of the sample, it was found that compression enhances the decoupling of electrical conductivity from the structural relaxation. Herein, we propose a new parameter, dlogRτ/dP, to quantify the pressure sensitivity of the decoupling phenomenon. Finally, the temperature and volume dependence of τσ is discussed in terms of thermodynamic scaling concept.
An indirectly pumped terahertz quantum cascade laser with low injection coupling strength operating above 150 K
Authors: Razavipour S. G. , Dupont E. , Fathololoumi S. , Chan C. W. I. , Lindskog M. , Wasilewski Z. R. , Aers G. , Laframboise S. R. , Wacker A. , Hu Q. , Ban D. , Liu H. C.
Published: May 2013

We designed and demonstrated a terahertz quantum cascade laser based on indirect pump injection to the upper lasing state and phonon scattering extraction from the lower lasing state. By employing a rate equation formalism and a genetic algorithm, an optimized active region design with four-well GaAs/Al0.25Ga0.75As cascade module was obtained and epitaxially grown. A figure of merit which is defined as the ratio of modal gain versus injection current was maximized at 150 K. A fabricated device with a Au metal-metal waveguide and a top n+ GaAs contact layer lased at 2.4 THz up to 128.5 K, while another one without the top n+ GaAs lased up to 152.5 K (1.3ℏω/kB). The experimental results have been analyzed with rate equation and nonequilibrium Green's function models. A high population inversion is achieved at high temperature using a small oscillator strength of 0.28, while its combination with the low injection coupling strength of 0.85 meV results in a low current. The carefully engineered wavefunctions enhance the quantum efficiency of the device and therefore improve the output optical power even with an unusually low injection coupling strength.
A non-contact strategy for controlled enrichment, manipulation, and separation of carbon nanotubes by surface acoustic waves
Authors: Zeng Qian , Li Lili , Ma Horse L. , Xu Junhua , Fan Yunshan , Wang Hao
Published: May 2013

We report a flexible method to manipulate carbon nanotubes (CNTs) in a microfluidic device employing surface acoustic waves (SAWs). First, CNTs in suspension were enriched to the surface of the piezoelectric substrate by SAW; standing SAWs (SSAWs) could orchestrate controllable alignment and movement of the CNTs in a microfluidic channel. In the two-dimensional (2D) case, moreover, the enriched and aligned CNTs could be precisely rotated to all directions via adjusting the coupling of the 2D SSAWs. Finally, we demonstrated the SAW technique as a promising candidate for purifying metallic single-walled carbon nanotubes from the mixture species in a non-contact manner.
Microstructure of bilayer manganite PrCa2Mn2O7 showing charge/orbital ordering
Authors: He Zhanbing , Tian He , Deng Guochu , Xu Qiang , Van Tendeloo Gustaaf
Published: May 2013

The microstructure of the charge/orbital ordering Ruddleden-Popper phase PrCa2Mn2O7 was studied by transmission electron microscopy along both the [001] and the [110] orientation. Three coexisting charge/orbital ordering phases CO1, CO2, and CO3 were observed along the [001] orientation at room temperature. Different from the one-dimensional modulation in the CO1 and CO2 phase, the CO3 phase is characterized by two sets of mutually perpendicular structural modulations. From [110] high angle annular dark field-scanning transmission electron microscopy, we found that the Pr atoms locate in-between the bilayer MnO6 octahedra, which is different from the previous reports.
Integration of on-chip field-effect transistor switches with dopantless Si/SiGe quantum dots for high-throughput testing
Authors: Ward D. R. , Savage D. E. , Lagally M. G. , Coppersmith S. N. , Eriksson M. A.
Published: May 2013

Measuring multiple quantum devices on a single chip increases characterization throughput and enables testing of device repeatability, process yield, and systematic variations in device design. We present a method that uses on-chip field-effect transistor switches to enable multiplexed cryogenic measurements of double quantum dot Si/SiGe devices. Multiplexing enables the characterization of a number of devices that scales exponentially with the number of external wires, a key capability given the significant constraints on cryostat wiring. Using this approach, we characterize three quantum-point contact channels and compare threshold voltages for accumulation and pinch-off voltages during a single cool-down of a dilution refrigerator.
Quantum-confined Stark effects in coupled InAs/GaAs quantum dots
Authors: Ramanathan Swati , Petersen Greg , Wijesundara Kushal , Thota Ramana , Stinaff E. A. , Kerfoot Mark L. , Scheibner Michael , Bracker Allan S. , Gammon D.
Published: May 2013

We report the effects of tunnel coupling on the Quantum-Confined Stark Effect (QCSE) for excitons in InAs/GaAs coupled quantum dots (CQDs). As the barrier separating the dots is reduced, the zero-field dipole moment and the polarizability are both found to increase. This systematic variation as a function of barrier thickness is due to factors including the formation of molecular wavefunctions, the electron/hole effective masses, and the CQD structural properties. The dipole moment for the interdot exciton is found to be up to 100 times larger than that of the intradot exciton resulting in a predominantly linear shift with field. The ability to control the QCSE of the exciton in a single CQD could be useful for a new class of single photon optical switches and tunable emitters.
Nickel: A very fast diffuser in silicon
Authors: Lindroos J. , Fenning D. P. , Backlund D. J. , Verlage E. , Gorgulla A. , Estreicher S. K. , Savin H. , Buonassisi T.
Published: May 2013

Nickel is increasingly used in both IC and photovoltaic device fabrication, yet it has the potential to create highly recombination-active precipitates in silicon. For nearly three decades, the accepted nickel diffusivity in silicon has been DNi(T)=2.3×10−3exp(−0.47 eV/kBT) cm2/s, a surprisingly low value given reports of rapid nickel diffusion in industrial applications. In this paper, we employ modern experimental methods to measure the higher nickel diffusivity DNi(T)=(1.69±0.74)×10−4exp(−0.15±0.04 eV/kBT) cm2/s. The measured activation energy is close to that predicted by first-principles theory using the nudged-elastic-band method. Our measured diffusivity of nickel is higher than previously published values at temperatures below 1150 °C, and orders of magnitude higher when extrapolated to room temperature.
Laser-induced periodic surface structure formation resulting from single-pulse ultrafast irradiation of Au microstructures on a Si substrate
Authors: Murphy Ryan D. , Torralva Ben , Adams David P. , Yalisove Steven M.
Published: May 2013

We have observed laser-induced periodic surface structure (LIPSS) formation with sub-micron periodicities after single-pulse ultrafast irradiation of isolated, 110 nm-tall Au microstructures on Si substrates. Fresnel diffraction patterns are established on both the structure surface and surrounding Si substrate when light is scattered by feature edges, and the resultant intensity distribution is partially responsible for LIPSS formation. LIPSS form for any in-plane, laser polarization orientation with respect to surface feature edges, although the LIPSS amplitude varies with the orientation. This explains the formation of LIPSS patterns having different wavevectors and amplitudes after multi-pulse irradiation of initially smooth surfaces.
Laser-excited terahertz-wave radiation from a thin wire
Authors: Chen Chia-Hsiang , Huang Kuan-Yan , Wu Ming-Hsiung , Chen Tzu-Hsiang , Huang Yen-Chieh
Published: May 2013

We report terahertz (THz) radiation from a 250-μm-diameter metal wire irradiated by a 160-fs infrared laser pulse. The detected radiation field is comparable to that from a 1-mm thick 〈110〉 ZnTe THz emitter under the same incident laser intensity of 280 GW/cm2. Photoemission is considered as the dominant mechanism to generate the transient radiation current in the wire.
Effects of valence band mixing on hole spin coherence via hole-nuclei hyperfine interaction in InAlAs quantum dots
Authors: Kaji R. , Ohno S. , Hozumi T. , Adachi S.
Published: May 2013

The effects of valence band mixing on the hole spin coherence in self-assembled InAlAs quantum dots are investigated. The valence band mixing induces not only optical anisotropy in the quantum dot emissions but also heavy hole spin dephasing via the hyperfine interaction with the lattice nuclei. We evaluated the degree of valence band mixing for a number of In0.75Al0.25As/Al0.3Ga0.7As quantum dots from experiments. The magnitude of valence band mixing does not show a clear dependence on the photoluminescence energy, and it is less than 0.25 in our sample. Although the direct measurement with experimental methods has not been carried out at this stage, the effect of valence band mixing on the hole spin coherence is discussed in detail by the calculations.
Study of domain structure of poled (K,Na)NbO3 ceramics
Authors: Qin Yalin , Zhang Jialiang , Gao Yong , Tan Yongqiang , Wang Chunlei
Published: May 2013

Domain structure may greatly affect the dielectric and piezoelectric properties of a ferroelectric ceramic material. However, no investigations on the domain structure of poled (K,Na)NbO3-based ceramics have been reported so far. Since (K0.50Na0.50)NbO3 is the basic composition for the important type of lead-free piezoelectric materials, domain structure of the poled (K0.50Na0.50)NbO3 ceramics with the average grain size of about 8 μm were explored by observing the domain patterns with an acid etching technique in this study. It was found that domain patterns show usually either a single set of parallel domain stripes or a few sets of parallel domain stripes in polycrystalline grains. The average domain widths in different sets of parallel domain stripes vary largely from 150 nm to 750 nm. The intersection angels between two adjacent sets of domain stripes are around 45° or 135°. Two models of domain configuration were proposed to explain those domain patterns that consist of more than two sets of parallel domain stripes. One is built up in the way that the intersection angles between two adjacent sets of domain stripes are acute and consists of 90°-, 60°- and 120°-domain walls. The other one is formed in the way that the intersection angles between two adjacent sets of domain stripes are obtuse and is composed of 180°-, 90°- and 120°-domain walls. Additionally, the change of intersection angle between two adjacent sets of domain stripes with varying the observation plane is discussed.
Design and fabrication of a high transmissivity metal-dielectric ultraviolet band-pass filter
Authors: Mu Jianwei , Lin Pao-Tai , Zhang Lin , Michel Jurgen , Kimerling L. C. , Jaworski Frank , Agarwal Anu
Published: May 2013

We introduce an efficient design approach for Ultraviolet (UV) band-pass filter based on metal-dielectric stacks. We present a general design method and then apply this design to two special cases: a UV band pass filter based on (i) Al/Al2O3 stacks as well as (ii) Ag/SiO2 stacks. As an experimental confirmation, we fabricate a UV filter with three Ag/SiO2 layer pairs on a fused silica substrate (Corning 7980), targeting a central wavelength of 320 nm. A measurement at the peak wavelength shows transmission efficiency as high as 67% in our filter.
Light induced diffusion driven self assembly of Ag nanoparticles in a-Se/Ag bi-layer thin film with ultrafast optical response
Authors: Bapna Mukund , Sharma Rituraj , Barik A. R. , Khan Pritam , Ranjan Kumar Rakesh , Adarsh K. V.
Published: May 2013

In this Letter, we demonstrate that femtosecond light-induced interdiffusion of Ag driven by the electrostatic attraction between photo-excited Ag+ ions and negatively charged amorphous layer can act as an efficient single step method for hybrid integration of spatially ordered and interconnected nanoparticles on the surface of amorphous films. Such self assembled complex hybrid structures of silver nanoparticles via bottom-up nano-construction method on a-Se thin film show an ultrafast optical response over an unusually broad wavelength range that can be used to construct optical modulators operating at switching speed of ∼5 ps.
Size effects of primary/secondary twins on the atomistic deformation mechanisms in hierarchically nanotwinned metals
Authors: Yuan Fuping , Wu Xiaolei
Published: May 2013

A series of large-scale molecular dynamics simulations have been performed to investigate the tensile properties of nanotwinned (NT) copper with hierarchically twinned structures (HTS). For the same grain size d and the same spacing of primary twins λ1, the average flow stress first increases as the spacing of secondary twins λ2 decreases, reaching a maximum at a critical λ2, and then decreases as λ2 becomes even smaller. The smaller the spacing for λ1, the smaller the critical spacing for λ2. There exists a transition in dominating deformation mechanisms, occurring at a critical spacing of λ2 for which strength is maximized. Above the critical spacing of λ2, the deformation mechanisms are dominated by the two Hall-Petch type strengthening mechanisms: (a) partial dislocations emitted from grain boundaries (GBs) travel across other GBs and twin boundaries (TBs); (b) partial dislocations emitted from TBs travel across other TBs. Below the critical spacing of λ2, the deformation mechanism is dominated by the two softening mechanisms: (a) Partial dislocations emitted from boundaries of the primary twins travel parallel to the TBs of the secondary twins, leading to detwinning of the secondary twins; (b) Boundaries of the primary twins shift entirely, leading to thickening in one part of primary twins and thinning in the other part of primary twins. The present results should provide insights to design the microstructures for reinforcing the mechanical properties in the NT metals with HTS.
Incorporating Spatial Autocorrelation with Neural Networks in Empirical Land-Use Change Models
Authors: Chu Hone-Jay , Wu Chen-Fa , Lin Yu-Pin
Published: May 2013

Land-use data can accurately reflect spatial pattern dependence (ie, spatial autocorrelation) and a nonlinear relationship with driving variables. In this study land-use dynamics in the Paochiao Watershed, Taiwan are forcast for the next fifteen years by incorporating artificial neural networks with spatial autocorrelation (Auto-ANNs) into the conversion of land use and its effects (CLUE-s) model. In addition to spatial autocorrelations of land use, Auto-ANNs-CLUE-s considers the nonlinear relationships between driving factors and land-use patterns. Results of a three-map comparison indicate that the Auto-ANNs-CLUE-s model has a better overall performance than Auto-logistic-CLUE-s. The Auto-ANNs-CLUE-s is highly applicable for all resolutions from multiresolution validation. The results of landscape metrics demonstrate the prevalence of urban sprawl in the study area. The proposed model is an alternative means of improving land use and environmental planning.
Multitype Green-Space Modeling for Urban Planning Using GA and GIS
Authors: Neema Meher Nigar , Ohgai Akira
Published: May 2013

Green spaces can facilitate sustainable urban environment in a number of ways: Purifying air and water, filtering noise, and stabilizing the microclimate. Therefore, city planners have to design optimal sites to provide new green spaces. The present study addresses the genetic-algorithm-based multiobjective modeling of optimal sites for multitype green spaces considering multiple objectives. A new model has been developed and applied to identify the optimum sites for green spaces, particularly parks and open spaces (POSs). We considered six criteria: population, air quality, noise level, air temperature, water quality, and recreational value, including barriers for placing new POSs. The model thus developed was applied to Dhaka as a case study. The spatial functions of GIS are used to quantify, analyze, and represent the six objective criteria of our model. The modeling results show a successful optimization of locations for new POS. In addition, a suitability analysis is performed to find locations of various POSs using GIS. This study provides an indication of how to site multitype green spaces to make a sustainable urban environment.
Production of high oleic rice grains by suppressing the expression of the OsFAD2-1 gene
Authors: Zaplin Ella Simone , Liu Qing , Li Zhongyi , Butardo Vito M. , Blanchard Christopher L. , Rahman Sadequr
Published: May 2013

The composition of rice (Oryza sativa L.) grain fatty acids (18% palmitic acid, 36% oleic acid and 37% linoleic acid) is suboptimal for rice storage and utilisation of rice bran oil as food grade oil or a source of biodiesel. Genetic manipulation of fatty acid composition in rice bran oil to increase oleic acid levels at the expense of linoleic acid and palmitic acid would not only add extra value to the rice, but also enhance health benefits for consumers. Four putative rice microsomal Δ12-fatty acid desaturase (OsFAD2) genes were identified as potentially important target genes to achieve this improvement. Reverse transcription–PCR analysis indicated that OsFAD2–1 was the most highly expressed gene in rice grains. RNA interference (RNAi) suppression of the expression of OsFAD2–1 resulted in an increase of oleic acid and a reduction of linoleic and palmitic acids in T3 grains. The research here showed that in the rice grains, the OsFAD2–1 enzyme was an effective target for raising oleic acid levels at the expense of the oxidatively unstable linoleic acid and the cholesterol-raising palmitic acid.
Spermatozoa from mice deficient in Niemann-Pick disease type C2 (NPC2) protein have defective cholesterol content and reduced in vitro fertilising ability
Authors: Busso Dolores , Oñate-Alvarado María José , Balboa Elisa , Castro Juan , Lizama Carlos , Morales Gabriela , Vargas Susana , Härtel Steffen , Moreno Ricardo D. , Zanlungo Silvana
Published: May 2013

The cholesterol content of the sperm membrane is regulated during both maturation in the epididymis and capacitation in the female tract, two processes required for the spermatozoa to acquire their fertilising ability. Because Niemann-Pick disease, type C2 (NPC2) protein is one of the most abundant components of the epididymal fluid and contains a functional cholesterol-binding site that can transfer cholesterol between membranes, it has been suggested for years that NPC2 could be involved in the regulation of cholesterol levels in spermatozoa during epididymal maturation. In the present study, western blot and immunohistochemistry analyses demonstrated significant levels of NPC2 in the mouse epididymal epithelium. Epididymal spermatozoa obtained from NPC2–/– mice were morphologically normal and had normal motility parameters, but had a reduced cholesterol content compared with that of wild-type (WT) spermatozoa, as determined by both biochemical and by flow cytometry analyses. These results suggest that NPC2 could be involved in regulating cholesterol levels in spermatozoa during epididymal maturation. To understand the relevance of epididymal NPC2 for sperm function, the ability of spermatozoa to undergo events influenced by epididymal maturation, such as capacitation and fertilisation, were compared between WT and NPC2–/– mice. Capacitated NPC2–/– spermatozoa exhibited defective tyrosine phosphorylation patterns and a reduced ability to fertilise cumulus–oocyte complexes compared with WT spermatozoa, supporting the relevance of mouse epididymal NPC2 for male fertility.
ZNF408
is mutated in familial exudative vitreoretinopathy and is crucial for the development of zebrafish retinal vasculature
Authors: Collin Rob W. J. , Nikopoulos Konstantinos , Dona Margo , Gilissen Christian , Hoischen Alexander , Boonstra F. Nienke , Poulter James A. , Kondo Hiroyuki , Berger Wolfgang , Toomes Carmel , Tahira Tomoko , Mohn Lucas R. , Blokland Ellen A. , Hetterschijt Lisette , Ali Manir , Groothuismink Johanne M. , Duijkers Lonneke , Inglehearn Chris F. , Sollfrank Lea , Strom Tim M. , Uchio Eiichi , van Nouhuys C. Erik , Kremer Hannie , Veltman Joris A. , van Wijk Erwin , Cremers Frans P. M.
Published: May 2013

Familial exudative vitreoretinopathy (FEVR) is a genetically heterogeneous disorder characterized by abnormal vascularization of the peripheral retina, which can result in retinal detachment and severe visual impairment. In a large Dutch FEVR family, we performed linkage analysis, exome sequencing, and segregation analysis of DNA variants. We identified putative disease-causing DNA variants in proline-alanine-rich ste20-related kinase (c.791dup; p.Ser265ValfsX64) and zinc finger protein 408 (
ZNF408
) (c.1363C>T; p.His455Tyr), the latter of which was also present in an additional Dutch FEVR family that subsequently appeared to share a common ancestor with the original family. Sequence analysis of
ZNF408
in 132 additional individuals with FEVR revealed another potentially pathogenic missense variant, p.Ser126Asn, in a Japanese family. Immunolocalization studies in COS-1 cells transfected with constructs encoding the WT and mutant ZNF408 proteins, revealed that the WT and the p.Ser126Asn mutant protein show complete nuclear localization, whereas the p.His455Tyr mutant protein was localized almost exclusively in the cytoplasm. Moreover, in a cotransfection assay, the p.His455Tyr mutant protein retains the WT ZNF408 protein in the cytoplasm, suggesting that this mutation acts in a dominant-negative fashion. Finally, morpholino-induced knockdown of
znf408
in zebrafish revealed defects in developing retinal and trunk vasculature, that could be rescued by coinjection of RNA encoding human WT ZNF408 but not p.His455Tyr mutant ZNF408. Together, our data strongly suggest that mutant ZNF408 results in abnormal retinal vasculogenesis in humans and is associated with FEVR.
Neurulation and neurite extension require the zinc transporter ZIP12 (
slc39a12
)
Authors: Chowanadisai Winyoo , Graham David M. , Keen Carl L. , Rucker Robert B. , Messerli Mark A.
Published: May 2013

Zn
2+
is required for many aspects of neuronal structure and function. However, the regulation of Zn
2+
in the nervous system remains poorly understood. Systematic analysis of tissue-profiling microarray data showed that the zinc transporter ZIP12 (
slc39a12
) is highly expressed in the human brain. In the work reported here, we confirmed that ZIP12 is a Zn
2+
uptake transporter with a conserved pattern of high expression in the mouse and
Xenopus
nervous system. Mouse neurons and Neuro-2a cells produce fewer and shorter neurites after ZIP12 knockdown without affecting cell viability. Zn
2+
chelation or loading in cells to alter Zn
2+
availability respectively mimicked or reduced the effects of ZIP12 knockdown on neurite outgrowth. ZIP12 knockdown reduces cAMP response element-binding protein activation and phosphorylation at serine 133, which is a critical pathway for neuronal differentiation. Constitutive cAMP response element-binding protein activation restores impairments in neurite outgrowth caused by Zn
2+
chelation or ZIP12 knockdown. ZIP12 knockdown also reduces tubulin polymerization and increases sensitivity to nocodazole following neurite outgrowth. We find that ZIP12 is expressed during neurulation and early nervous system development in
Xenopus tropicalis,
where ZIP12 antisense morpholino knockdown impairs neural tube closure and arrests development during neurulation with concomitant reduction in tubulin polymerization in the neural plate. This study identifies a Zn
2+
transporter that is specifically required for nervous system development and provides tangible links between Zn
2+
, neurulation, and neuronal differentiation.
AG10 inhibits amyloidogenesis and cellular toxicity of the familial amyloid cardiomyopathy-associated V122I transthyretin
Authors: Penchala Sravan C. , Connelly Stephen , Wang Yu , Park Miki S. , Zhao Lei , Baranczak Aleksandra , Rappley Irit , Vogel Hannes , Liedtke Michaela , Witteles Ronald M. , Powers Evan T. , Reixach Natàlia , Chan William K. , Wilson Ian A. , Kelly Jeffery W. , Graef Isabella A. , Alhamadsheh Mamoun M.
Published: May 2013

The misassembly of soluble proteins into toxic aggregates, including amyloid fibrils, underlies a large number of human degenerative diseases. Cardiac amyloidoses, which are most commonly caused by aggregation of Ig light chains or transthyretin (TTR) in the cardiac interstitium and conducting system, represent an important and often underdiagnosed cause of heart failure. Two types of TTR-associated amyloid cardiomyopathies are clinically important. The Val122Ile (V122I) mutation, which alters the kinetic stability of TTR and affects 3% to 4% of African American subjects, can lead to development of familial amyloid cardiomyopathy. In addition, aggregation of WT TTR in individuals older than age 65 y causes senile systemic amyloidosis. TTR-mediated amyloid cardiomyopathies are chronic and progressive conditions that lead to arrhythmias, biventricular heart failure, and death. As no Food and Drug Administration-approved drugs are currently available for treatment of these diseases, the development of therapeutic agents that prevent TTR-mediated cardiotoxicity is desired. Here, we report the development of AG10, a potent and selective kinetic stabilizer of TTR. AG10 prevents dissociation of V122I-TTR in serum samples obtained from patients with familial amyloid cardiomyopathy. In contrast to other TTR stabilizers currently in clinical trials, AG10 stabilizes V122I- and WT-TTR equally well and also exceeds their efficacy to stabilize WT and mutant TTR in whole serum. Crystallographic studies of AG10 bound to V122I-TTR give valuable insights into how AG10 achieves such effective kinetic stabilization of TTR, which will also aid in designing better TTR stabilizers. The oral bioavailability of AG10, combined with additional desirable drug-like features, makes it a very promising candidate to treat TTR amyloid cardiomyopathy.
Protein kinase G oxidation is a major cause of injury during sepsis
Authors: Rudyk Olena , Phinikaridou Alkystis , Prysyazhna Oleksandra , Burgoyne Joseph R. , Botnar René M. , Eaton Philip
Published: May 2013

Sepsis is a common life-threatening clinical syndrome involving complications as a result of severe infection. A cardinal feature of sepsis is inflammation that results in oxidative stress. Sepsis in wild-type mice induced oxidative activation of cGMP-dependent protein kinase 1 alpha (PKG Iα), which increased blood vessel dilation and permeability, and also lowered cardiac output. These responses are typical features of sepsis and their combined effect is a lowering of blood pressure. This hypotension, a hallmark of sepsis, resulted in underperfusion of end organs, resulting in their damage. A central role for PKG Iα oxidative activation in injury is supported by oxidation-resistant Cys42Ser PKG Iα knock-in mice being markedly protected from these clinical indices of injury during sepsis. We conclude that oxidative activation of PKG Iα is a key mediator of hypotension and consequential organ injury during sepsis.
Toll-like receptor 3 (TLR3) activation induces microRNA-dependent reexpression of functional RARβ and tumor regression
Authors: Galli Roberta , Paone Alessio , Fabbri Muller , Zanesi Nicola , Calore Federica , Cascione Luciano , Acunzo Mario , Stoppacciaro Antonella , Tubaro Andrea , Lovat Francesca , Gasparini Pierluigi , Fadda Paolo , Alder Hansjuerg , Volinia Stefano , Filippini Antonio , Ziparo Elio , Riccioli Anna , Croce Carlo M.
Published: May 2013

Toll-like receptor 3 (TLR3) is a key effector of the innate immune system against viruses. Activation of TLR3 exerts an antitumoral effect through a mechanism of action still poorly understood. Here we show that TLR3 activation by polyinosinic:polycytidylic acid induces up-regulation of microRNA-29b, -29c, -148b, and -152 in tumor-derived cell lines and primary tumors. In turn, these microRNAs induce reexpression of epigenetically silenced genes by targeting DNA methyltransferases. In DU145 and TRAMP-C1 prostate and MDA-MB-231 breast cancer cells, we demonstrated that polyinosinic:polycytidylic acid-mediated activation of TLR3 induces microRNAs targeting DNA methyltransferases, leading to demethylation and reexpression of the oncosuppressor retinoic acid receptor beta (RARβ). As a result, cancer cells become sensitive to retinoic acid and undergo apoptosis both in vitro and in vivo. This study provides evidence of an antitumoral mechanism of action upon TLR3 activation and the biological rationale for a combined TLR3 agonist/retinoic acid treatment of prostate and breast cancer.
Recapitulating maladaptive, multiscale remodeling of failing myocardium on a chip
Authors: McCain Megan L. , Sheehy Sean P. , Grosberg Anna , Goss Josue A. , Parker Kevin Kit
Published: May 2013

The lack of a robust pipeline of medical therapeutic agents for the treatment of heart disease may be partially attributed to the lack of in vitro models that recapitulate the essential structure–function relationships of healthy and diseased myocardium. We designed and built a system to mimic mechanical overload in vitro by applying cyclic stretch to engineered laminar ventricular tissue on a stretchable chip. To test our model, we quantified changes in gene expression, myocyte architecture, calcium handling, and contractile function and compared our results vs. several decades of animal studies and clinical observations. Cyclic stretch activated gene expression profiles characteristic of pathological remodeling, including decreased α- to β-myosin heavy chain ratios, and induced maladaptive changes to myocyte shape and sarcomere alignment. In stretched tissues, calcium transients resembled those reported in failing myocytes and peak systolic stress was significantly reduced. Our results suggest that failing myocardium, as defined genetically, structurally, and functionally, can be replicated in an in vitro microsystem by faithfully recapitulating the structural and mechanical microenvironment of the diseased heart.
Quorum-sensing autoinducers resuscitate dormant
Vibrio cholerae
in environmental water samples
Authors: Bari S. M. Nayeemul , Roky M. Kamruzzaman , Mohiuddin M. , Kamruzzaman M. , Mekalanos John J. , Faruque Shah M.
Published: May 2013

Cholera epidemics have long been known to spread through water contaminated with human fecal material containing the toxigenic bacterium
Vibrio cholerae
. However, detection of
V. cholerae
in water is complicated by the existence of a dormant state in which the organism remains viable, but resists cultivation on routine bacteriological media. Growth in the mammalian intestine has been reported to trigger “resuscitation” of such dormant cells, and these studies have prompted the search for resuscitation factors. Although some positive reports have emerged from these investigations, the precise molecular signals that activate dormant
V. cholerae
have remained elusive. Quorum-sensing autoinducers are small molecules that ordinarily regulate bacterial gene expression in response to cell density or interspecies bacterial interactions. We have found that isolation of pathogenic clones of
V. cholerae
from surface waters in Bangladesh is dramatically improved by using enrichment media containing autoinducers either expressed from cloned synthase genes or prepared by chemical synthesis. These results may contribute to averting future disasters by providing a strategy for early detection of
V. cholerae
in surface waters that have been contaminated with the stools of cholera patients or asymptomatic infected human carriers.
Metabolic sensor AMPK directly phosphorylates RAG1 protein and regulates V(D)J recombination
Authors: Um Jee-Hyun , Brown Alexandra L. , Singh Samarendra K. , Chen Yong , Gucek Marjan , Lee Baeck-Seung , Luckey Megan A. , Kim Myung K. , Park Jung-Hyun , Sleckman Barry P. , Gellert Martin , Chung Jay H.
Published: May 2013

The ability to sense metabolic stress is critical for successful cellular adaptation. In eukaryotes, the AMP-activated protein kinase (AMPK), a highly conserved serine/threonine kinase, functions as a critical metabolic sensor. AMPK is activated by the rising ADP/ATP and AMP/ATP ratios during conditions of energy depletion and also by increasing intracellular Ca
2+
. In response to metabolic stress, AMPK maintains energy homeostasis by phosphorylating and regulating proteins that are involved in many physiological processes including glucose and fatty acid metabolism, transcription, cell growth, mitochondrial biogenesis, and autophagy. Evidence is mounting that AMPK also plays a role in a number of pathways unrelated to energy metabolism. Here, we identify the recombination-activating gene 1 protein (RAG1) as a substrate of AMPK. The RAG1/RAG2 complex is a lymphoid-specific endonuclease that catalyzes specific DNA cleavage during V(D)J recombination, which is required for the assembly of the Ig and T-cell receptor genes of the immune system. AMPK directly phosphorylates RAG1 at serine 528, and the phosphorylation enhances the catalytic activity of the RAG complex, resulting in increased cleavage of oligonucleotide substrates in vitro, or increased recombination of an extrachromosomal substrate in a cellular assay. Our results suggest that V(D)J recombination can be regulated by AMPK activation, providing a potential new link between metabolic stress and development of B and T lymphocytes.
Rapid Visual Assessment to Determine Sex in Brook Trout
Authors: Kazyak David C. , Hilderbrand Robert H. , Holloway Amanda E.
Published: May 2013

Although sex-specific processes play a considerable role in the ecology of many fishes, nonlethal tools to determine sex in most species outside of the spawning season are lacking. We identified a suite of sexual characteristics in Brook Trout Salvelinus fontinalis by surveying the available literature, consulting biologists, and reviewing images of known-sex individuals. Using pretraining and posttraining testing of fisheries professionals, we assessed the utility of color and morphology for sexing fish across a length gradient (110–251 mm TL) by presenting images of mature fish collected during the spawning season. Rapid visual assessment proved to be an effective approach for determining the sex of Brook Trout. Average accuracy significantly improved from 71.5% before training to 92% after training, and the proportion of fish scored as unknown was reduced (from 9.5% before to 2.0% after training). We found a small yet significant positive relationship between TL and the proportion of fish that were correctly sexed. With the exception of a single 113-mm male, all individuals were correctly sexed by at least 79% of respondents after training. No significant differences were found among respondents based on education, experience, or confidence level. The effectiveness of rapid visual assessment also did not significantly differ between male and female Brook Trout. Rapid visual assessment is a viable technique for the determination of sex in Brook Trout.

Received September 18, 2012; accepted March 6, 2013
First Report of Leaf Spot on Onion Caused by Fusarium acuminatum in Georgia
Authors: Parkunan V. , Ji P.
Published: May 2013

An unknown disease was observed on shallot onions (Allium cepa L.) in Tattnall County, Georgia, in September of 2012. Disease symptoms included leaf tip die back and scattered light brown lesions on leaves, oval to round in shape, with a size ranging from 0.5 to 2.0 cm. The disease occurred in approximately 1.2 ha of commercial onion fields, and disease incidence ranged from 50 to 70%. Infected leaf tissues from 10 plants were surface sterilized with 0.5% NaOCl and plated on quarter-strength potato dextrose agar (QPDA). The fungus grew on all plates, producing bright orange to rose pigmentation in the medium after incubation at 25°C for 5 days. The fungus produced sickle shaped macroconidia with 3 to 6 septa, 4 to 5 μm wide, and 30 to 54 μm in length. Chlamydospores were formed in chains and averaged 20.4 × 16.8 μm. The fungus was identified as Fusarium sp. based on morphological characteristics (3). Genomic DNA was extracted from single conidial cultures of three representative isolates and the internal transcribed spacer regions of rDNA (ITS1-5.8S-ITS2) were amplified and sequenced with primers ITS1 and ITS4 (2). MegaBLAST analysis of the sequences showed that they were 100% identical to a Fusarium acuminatum isolate (Accession No. JN624894). ITS sequence of an isolate FAON-1 was deposited in GenBank (KC477845). Pathogenicity tests were performed with the three isolates grown on QPDA at 25°C for 7 days. Eight-week-old shallot onion seedlings were inoculated by foliar spray with conidial suspensions at 2 × 106 spores/ml (5 ml per plant). Ten plants were inoculated with each isolate and 10 plants were sprayed with water as a control. The plants were incubated in a humidified chamber at (25 ± 3°C) with >95% relative humidity and 12-h photoperiod for 48 h after inoculation, and then kept in a greenhouse at 22 ± 2°C. Inoculated plants started to show symptoms identical to those observed in the field 7 days after inoculation, and disease incidence reached 100% within 14 days. No disease occurred on the control plants. The fungus was reisolated from the diseased plants and confirmed to be F. acuminatum based on morphological characteristics and molecular identification. Onion was previously reported to be a host of F. acuminatum in Montana (4). To our knowledge, this study is the first report confirming F. acuminatum causing disease on onion in Georgia. Onion is a major vegetable crop in Georgia with an annual production of approximately 5,000 ha (1). Occurrence of leaf spot caused by F. acuminatum and the impact of the disease needs to be considered in developing and implementing disease management programs in onion production.

References: (1) S. R. Boatright and J. C. Mckissick, Univ. of Georgia CAES Publication AR-10-02, 2010. (2) M. A. Innes et al. PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA. 1990. (3) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Ames, IA, 2006. (4) C. G. Shaw. Washington State Univ. Agric. Exp. Sta. Bull. 765:12, 1973.
First Report of ‘Candidatus Phytoplasma mali,’ the Causal Agent of Apple Proliferation Disease, in Apple Trees in Finland
Authors: Lemmetty A. , Soukainen M. , Tuovinen T.
Published: May 2013

Based on an earlier survey of putative psyllid vectors of apple proliferation (AP), carried out in 2009 and 2010, Cacopsylla picta (Förster) populations infected with ‘Candidatus Phytoplasma mali’ were detected in at least two commercial apple (Malus domestica Borkh.) orchards in southern Finland (1). To establish the presence of ‘Ca. P. mali’ in apple trees, a survey was conducted in 17 commercial apple orchards in August 2012. Phytosanitary inspectors tracked the source of the ‘Ca. P. mali’ by collecting 33 leaf samples from trees showing probable symptoms. Typical symptoms, including elongated stipules and witches' broom, were rare. Total DNA was extracted from leaves using a DNeasy Plant Mini Kit (Qiagen, Hilden, Germany) and screened for ‘Ca. P. mali’ with real-time PCR (2) and the commercial Apple Proliferation Group – complete PCR reaction kit (Loewe Biochemica GmbH, Sauerlach, Germany). Two samples tested positive and results were confirmed with TaqMan PCR and conventional PCR assays and DNA sequencing in the Food and Environment Research Agency (Fera), in the United Kingdom. One positive sample was taken from an orchard in Lohja, southern Finland, where high ‘Ca. P. mali’ incidence in overwintered C. picta was observed in 2010 (1). ‘Ca. P. mali’ was found in a >40-year-old ‘Red Melba’ tree with witches' broom but without elongated stipule symptoms. The other positive sample was collected from an orchard in the Aland Islands, where the infected ‘Lobo’ tree showed symptoms of elongated stipules. This orchard was not monitored for AP vectors. No small fruit symptoms were noted by inspectors or growers in either of the orchards. The positive samples were further analyzed for subtypes using PCR/RFLP and primers AP13/AP10 (3). The amplicons (776 bp) were sequenced and digested with HincII and BspHI (New England BioLabs Inc., Ipswich, MA) following manufacturer's instructions. Both samples proved to be apple proliferation subtypes AT-1 on the basis of RFLP and the sequenced 776-bp region. Sequences of the 776-bp amplicon of the Lohja and Aland isolates showed 100% and 99% identity, respectively, with sequences of apple proliferation isolates (accession nos. L22217.1 and CU469464.1) in GenBank. Both suspected psyllid vectors of ‘Ca. P. mali’ C. picta and C. melanoneura (Förster) occur in Finland, but their distribution, abundance, and transmission specificity is inadequately documented. The next step to evaluate the risk of spread of apple proliferation in commercial orchards is an extensive survey of the occurrence of Cacopsylla species infected with ‘Ca. P. mali’.

References: (1) A. Lemmetty et al. B. Insectol. 64:257, 2011. (2) P. Nikolić et al. Mol. Cell. Probes. 24:303, 2010. (3) W. Jarausch et al. Mol. Cell. Probes 14:17, 2000.
Evaluation of Selected Cucurbitaceous Vegetables for Resistance toZucchini yellow mosaic virus
Authors: Svoboda J. , Leisova-Svobodova L. , Amano M.
Published: May 2013

Zucchini yellow mosaic virus (ZYMV) causes considerable losses of cucurbitaceous vegetables grown nearly all over the world; indeed, the commonly planted cultivars are highly susceptible to ZYMV. In all, 3 cultivars of American and 8 of European summer squash (Cucurbita pepo), and 6 Japanese and 21 European cucumber lines (Cucumis sativus), including both slicing and pickling species, were selected for the evaluation of their resistance to the most virulent Czech strain, ZYMV-H (GenBank accession number DQ144054). Butternut squash (Cucurbita moschata) ‘Menina 15’, Chinese slicing cucumber ‘Taichung Mou Gua-1’ (TMG-1), and watermelon (Citrullus lanatus) accession PI 595203 were included in the experiment, because they were reported to be resistant to ZYMV. The tested plants were mechanically inoculated by ZYMV-H and their resistance was assessed through a comparison of the relative virus protein concentrations and visual symptoms. Butternut squash Menina 15, Chinese slicing cucumber TMG-1, Japanese slicing cucumber breeds ‘G22' and ‘A192-18’, and watermelon PI 595203 were evaluated as immune: the virus concentration in their leaves was zero, as verified by polymerase chain reaction. American summer squash ‘Cougar’ and Japanese slicing cucumber breeds ‘A202-18’, ‘R10’, and ‘S93-18’ were clearly resistant, because the virus multiplied at a low rate in these plants. The remaining tested cultivars were tolerant or susceptible to ZYMV.
Effect of Intraoperative High Inspired Oxygen Fraction on Surgical Site Infection, Postoperative Nausea and Vomiting, and Pulmonary Function
Authors: Hovaguimian Frédérique , Lysakowski Christopher , Elia Nadia , Tramèr Martin R.
Published: May 2013

Background:

Intraoperative high inspired oxygen fraction (Fio
2) is thought to reduce the incidence of surgical site infection (SSI) and postoperative nausea and vomiting, and to promote postoperative atelectasis.

Methods:

The authors searched for randomized trials (till September 2012) comparing intraoperative high with normal Fio
2 in adults undergoing surgery with general anesthesia and reporting on SSI, nausea or vomiting, or pulmonary outcomes.

Results:

The authors included 22 trials (7,001 patients) published in 26 reports. High Fio
2 ranged from 80 to 100% (median, 80%); normal Fio
2 ranged from 30 to 40% (median, 30%). In nine trials (5,103 patients, most received prophylactic antibiotics), the incidence of SSI decreased from 14.1% with normal Fio
2 to 11.4% with high Fio
2; risk ratio, 0.77 (95% CI, 0.59–1.00). After colorectal surgery, the incidence of SSI decreased from 19.3 to 15.2%; risk ratio, 0.78 (95% CI, 0.60–1.02). In 11 trials (2,293 patients), the incidence of nausea decreased from 24.8% with normal Fio
2 to 19.5% with high Fio
2; risk ratio, 0.79 (95% CI, 0.66–0.93). In patients receiving inhalational anesthetics without prophylactic antiemetics, high Fio
2 provided a significant protective effect against both nausea and vomiting. Nine trials (3,698 patients) reported on pulmonary outcomes. The risk of atelectasis was not increased with high Fio
2.

Conclusions:

Intraoperative high Fio
2 further decreases the risk of SSI in surgical patients receiving prophylactic antibiotics, has a weak beneficial effect on nausea, and does not increase the risk of postoperative atelectasis.
Spatial learning affects thread tension control in orb-web spiders
Authors: Nakata Kensuke
Published: May 2013

Although it is well known that spatial learning can be important in the biology of predators that actively move around in search for food, comparatively little is known about ways in which spatial learning might function in the strategies of sit-and-wait predators. In this study,
Cyclosa octotuberculata
, an orb-web spider that uses its legs to contract radial threads of its web to increase thread tension, was trained to capture prey in limited web sectors. After training, spiders that had captured prey in horizontal web sectors applied more tension on radial threads connected to horizontal sectors than spiders that had captured prey in vertical sectors. This result suggests that the effect of experience on
C. octotuberculata
's behaviour is not expressed in the way the trained spider responds to prey-derived stimuli and is instead expressed in behaviour by which the spider anticipates the likely direction from which prey will arrive in the future. This illustrates that learning can be important even when the predator remains in one location during foraging bouts.