bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface fingerprints of individual silicon nanocrystals in laser-annealed Si/SiO2 superlattice: Evidence of nanoeruptions of laser-pressurized silicon
Authors: Nikitin Timur , Kemell Marianna , Puukilainen Esa , Boninelli Simona , Iacona Fabio , Räsänen Markku , Ritala Mikko , Novikov Sergei , Khriachtchev Leonid
Published: June 2012

Silicon nanocrystals prepared by continuous-wave laser annealing of a free-standing Si/SiO2 superlattice are studied for the first time by using methods of surface analysis (scanning electron microscopy and atomic force microscopy). The surface topology and composition are compared with transmission electron microscopy images that show a projection through the whole film, allowing us to discriminate silicon nanocrystals located near the film surface. These nanocrystals have an unusual pear-like shape with the thinner part sticking out of the laser-illuminated surface. The non-spherical shape of these nanocrystals is explained by eruption of silicon pressurized at the stage of crystallization from the melt phase. This hypothesis is supported by the micro-Raman spectra which show low stress near the surface features, in contrast to the neighbouring regions having high compressive stress.
On the oscillator strength in dilute nitride quantum wells on GaAs
Authors: Ryczko K. , Sęk G. , Misiewicz J. , Langer F. , Höfling S. , Kamp M.
Published: June 2012

We have investigated theoretically two kinds of dilute-nitride-based quantum well structures, InGaAsN/GaAs and InGaAsN/GaAsN/GaAs, both able to emit at 1.3 μm. The ground state transition energy and its oscillator strength have been probed as a function of the material composition in the single particle as well as the excitonic approximations. The modification of the bandgap energy due to nitrogen incorporation has been taken into account by using a two-level repulsion model. We have shown that in spite of a decrease of the electron-hole wave functions overlap with the mole fraction of nitrogen, the overall transition intensity of the excitonic transition can increase significantly due to the strongly composition dependent mass of the exciton. The latter makes dilute nitride quantum wells good candidates for the polaritonic physics and Bose-Einstein condensation of exciton polaritons at telecommunication wavelengths. We have also demonstrated that the exact values of the band offsets are necessary to be known as they have a critical impact on the actual transition oscillator strengths in these quantum wells.
Minimum thermal conductivity considerations in aerogel thin films
Authors: Hopkins Patrick E. , Kaehr Bryan , Piekos Edward S. , Dunphy Darren , Jeffrey Brinker C.
Published: June 2012

We demonstrate the use time domain thermoreflectance (TDTR) to measure the thermal conductivity of the solid silica network of aerogel thin-films. TDTR presents a unique experimental capability for measuring the thermal conductivity of porous media due to the nanosecond time domain aspect of the measurement. In short, TDTR is capable of explicitly measuring the change in temperature with time of the solid portion of porous media independently from the pores or effective media. This makes TDTR ideal for determining the thermal transport through the solid network of the aerogel film. We measure the thermal conductivity of the solid silica networks of an aerogel film that is 10% solid, and the thermal conductivity of the same type of film that has been calcined to remove the terminating methyl groups. We find that for similar densities, the thermal conductivity through the silica in the aerogel thin films is similar to that of bulk aerogels. We theoretically describe the thermal transport in the aerogel films with a modified minimum limit to thermal conductivity that accounts for porosity through a reduction in phonon velocity. Our porous minimum limit agrees well with a wide range of experimental data in addition to sound agreement with differential effective medium theory. This porous minimum limit therefore demonstrates an approach to predict the thermal conductivity of porous disordered materials with no a priori knowledge of the corresponding bulk phase, unlike differential effective medium theory.
Quantum dot photodegradation due to CdSe-ZnO charge transfer: Transient absorption study
Authors: Žídek K. , Zheng K. , Chábera P. , Abdellah M. , Pullerits T.
Published: June 2012

We study changes in ultrafast transient absorption due to photodegradation of quantum dots attached to ZnO nanowire. The time-resolved measurements reveal impact of photodegradation on three distinct kinetic components present in transient absorption τ ∼ 7 ps, 80 ps, and 7.5 ns). In addition, we observe superlinear dependence of photodegradation rate on concentration of excited electrons. The data are used to evaluate the mean electron back-recombination time of ∼1 μs.
New insights on strain energies in hexagonal systems
Authors: Thuinet Ludovic , Besson Rémy
Published: June 2012

The preferential habit planes of coherent precipitates, strongly influencing alloy properties, can be investigated by direct-space elasticity methods, providing new insight into delicate issues such as elastic inhomogeneities or anharmonicity. Focusing on the poorly known hexagonal system, this work enlightens important trends overlooked hitherto, such as the critical role of C44, leading to the identification of distinct families of hexagonal alloys for precipitation. Moreover, it demonstrates the complex influence of inhomogeneities for real, finite-thickness morphologies. Finally, it provides the missing material required for atomic-scale studies of precipitation in low-symmetry systems with long-range interactions.
Efficient single-photon extraction from quantum-dots embedded in GaAs micro-pyramids
Authors: Rülke Daniel , Schaadt Daniel M. , Kalt Heinz , Hetterich Michael
Published: June 2012

We demonstrate an easy method to fabricate efficient single-photon sources based on In(Ga)As quantum-dots embedded in reversed GaAs micro-pyramids. It relies on a single wet-chemical etching step utilizing an AlAs sacrificial layer. Due to the pyramidal shape of the cavities, we have been able to separate a small number of quantum-dots from the self-assembled ensemble and improve the extraction efficiency for single photons. The latter is predicted by finite difference time domain and finite elements method simulations to be about 80%–90% over a broad spectral range of 40 nm. Single-photon emission has been proven experimentally by means of auto-correlation measurements.
Investigations of Bragg reflectors in nanowire lasers
Authors: Svendsen Guro K. , Weman Helge , Skaar Johannes
Published: June 2012

The reflectivity of various Bragg reflectors in connection to waveguide structures, including nanowires, has been investigated using modal reflection and transmission matrices. A semi-analytical model was applied yielding increased understanding of the diffraction effects present in such gratings. Planar waveguides and nanowire lasers are considered in particular. Two geometries are compared; Bragg reflectors within the waveguides are shown to have significant advantages compared to Bragg reflectors in the substrate, when diffraction effects are significant.
Tunable device properties of free-standing inorganic/organic flexible hybrid structures obtained by exfoliation
Authors: Shetty Amitha , Nanda Karuna Kar
Published: June 2012

We report the fabrication of free-standing flexible inorganic/organic hybrid structures by exfoliating ZnO nanostructured films from the flat indium tin oxide (ITO)/silicon/sapphire substrates using poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS). Strong interaction between ZnO and PEDOT:PSS and the thermomechanical response of PEDOT:PSS are the key issues for the exfoliation to prevail. The performance of the free-standing hybrid structures as rectifiers and photodetectors is better as compared to ITO supported hybrid structures. It is also shown that device properties of hybrid structures can be tuned by using different electrode materials.
The influence of substrate morphology on thickness uniformity and unintentional doping of epitaxial graphene on SiC
Authors: Eriksson Jens , Pearce Ruth , Iakimov Tihomir , Virojanadara Chariya , Gogova Daniela , Andersson Mike , Syväjärvi Mikael , Lloyd Spetz Anita , Yakimova Rositza
Published: June 2012

A pivotal issue for the fabrication of electronic devices on epitaxial graphene on SiC is controlling the number of layers and reducing localized thickness inhomogeneities. Of equal importance is to understand what governs the unintentional doping of the graphene from the substrate. The influence of substrate surface topography on these two issues was studied by work function measurements and local surface potential mapping. The carrier concentration and the uniformity of epitaxial graphene samples grown under identical conditions and on substrates of nominally identical orientation were both found to depend strongly on the terrace width of the SiC substrate after growth.
An enhancement of a thermoelectric power factor in a Ga-doped ZnO system: A chemical compression by enlarged Ga solubility
Authors: Jung Kwang-Hee , Hyoung Lee Kyu , Seo Won-Seon , Choi Soon-Mok
Published: June 2012

Herein, we report a significant enhancement of the thermoelectric power factor in polycrystalline Ga-doped ZnO. Despite its higher carrier concentration, the Seebeck coefficient of Zn0.985Ga0.015O was larger than that of Zn0.990Ga0.010O benefiting from an enhancement of the density of states (DOS) effective mass. A gradual increase in the compressive stress with Ga substitution gave rise to a higher DOS at the bottom of the conduction band. An enlarged solution limit of Ga in the ZnO matrix due to a lower firing temperature accelerated the chemical compression. A single phase n-type Zn0.985Ga0.015O bulk exhibited a power factor of 12.5 μWcm−1 K−2.
Ideal transparent conductors for full spectrum photovoltaics
Authors: Yu Kin Man , Mayer Marie A. , Speaks Derrick T. , He Hongcai , Zhao Ruying , Hsu L. , Mao Samuel S. , Haller E. E. , Walukiewicz Wladek
Published: June 2012

In current technologies, state-of-the-art transparent conducting oxides exhibit good conductivity (∼5 × 103 S/cm) and transparency up to only λ ∼ 1000 nm, restricting the use of such thin films to photovoltaics that are not utilizing the infrared part of the solar spectrum. We have found that among metal oxides, high electron mobility CdO satisfies the essential requirements for a low resistance and high infrared transmission transparent contact. With appropriate intentional doping, we have achieved ideal uncompensated CdO with extremely high conductivity (>104 S/cm) and an excellent transmission window in the range from 400 to >1500 nm, making this material an ideal TCO for photovoltaics with low band gap absorbers.
Optimization of enzymatic hydrolysis of prairie cordgrass for improved ethanol production
Authors: Zambare Vasudeo P. , Zambare Archana V. , Barh Debmalya , Christopher Lew P.
Published: June 2012

Prairie cordgrass (PCG), Spartina pectinata, is considered an energy crop with potential for bioethanol production in North America. The focus of this study was to optimize enzymatic hydrolysis of PCG at higher solids loadings using a thermostable cellulase of a mutant Penicillium pinophilum ATCC 200401. A three variable, five-level central composite design of response surface methodology (RSM) was employed in a total of 20 experiments to model and evaluate the impact of pH (4.1–6.0), solids loadings (6.6%–23.4%), and enzyme loadings (6.6–23.4 FPU/g dry matter, DM) on glucose yield from a thermo-mechanically extruded PCG. The extruded PCG was first hydrolyzed with the crude P. pinophilum cellulase and then fermented to ethanol with Saccharomyces cerevisiae ATCC 24860. Although all three variables had a significant impact, the enzyme loadings proved the most significant parameter for maximizing the glucose yield. A partial cubic equation could accurately model the response surface of enzymatic hydrolysis as the analysis of variance showed a coefficient of determination (R2) of 0.89. At the optimal conditions of pH of 4.5, solids loadings of 10% and enzyme loadings of 20 FPU/g DM, the enzymatic hydrolysis of pretreated PCG produced a glucose yield of 76.1% from the maximum yield which represents an increase of 15% over the non-optimized controls at the zero-level central points. The predicted results based on the RSM regression model were in good agreement with the actual experimental values. The model can present a rapid means for estimating lignocellulose conversion yields within the selected ranges. Furthermore, statistical optimization of solids and enzyme loadings of enzymatic hydrolysis of biomass may have important implications for reduced capital and operating costs of ethanol production.
Positronium formation in positron-hydrogen collisions with Debye potentials
Authors: Ma J. , Cheng Y. , Wang Y. C. , Zhou Y.
Published: June 2012

Positronium (Ps) formation cross sections (n = 1, 2) in positron-hydrogen collisions in Debye plasma environment are calculated using the screening approximation model for various Debye screening lengths from the Ps formation thresholds to 50 eV. The effect of the screened Coulomb potential on Ps formation process is investigated by using the Debye-Hückel potential. The present results are compared with available theoretical calculations.
The effect of applied electric field on pulsed radio frequency and pulsed direct current plasma jet array
Authors: Hu J. T. , Liu X. Y. , Liu J. H. , Xiong Z. L. , Liu D. W. , Lu X. P. , Iza F. , Kong M. G.
Published: June 2012

Here we compare the plasma plume propagation characteristics of a 3-channel pulsed RF plasma jet array and those of the same device operated by a pulsed dc source. For the pulsed-RF jet array, numerous long life time ions and metastables accumulated in the plasma channel make the plasma plume respond quickly to applied electric field. Its structure similar as “plasma bullet” is an anode glow indeed. For the pulsed dc plasma jet array, the strong electric field in the vicinity of the tube is the reason for the growing plasma bullet in the launching period. The repulsive forces between the growing plasma bullets result in the divergence of the pulsed dc plasma jet array. Finally, the comparison of 309 nm and 777 nm emissions between these two jet arrays suggests the high chemical activity of pulsed RF plasma jet array.
Generation, annihilation, dynamics and self-organized patterns of filaments in dielectric barrier discharge plasmas
Authors: Boeuf J. P. , Bernecker B. , Callegari Th. , Blanco S. , Fournier R.
Published: June 2012

Dielectric barrier discharges (DBDs) operating in a glow regime exhibit a variety of complex self-organized static or dynamical structures of filaments. Using a fluid model combined with fast camera diagnostics, we propose a clear physical description and explanation of the mechanisms responsible for the generation, annihilation, motion and self-organization of discharge filaments in DBDs in a glow regime. We show that low current “side discharges” generated during the same half-cycle in the vicinity of an isolated filament beyond the inhibition zone associated with charge spreading along the dielectric surface play an essential role in the triggering of these mechanisms.
Throwing results
Authors: Skallman Emma
Published: June 2012

This article explores synonymy and polysemy in the interaction of meaning and the elements that a verb combines with. It presents a corpus-based analysis of four Spanish verbs (tirar, lanzar, arrojar and echar) whose primary meaning is ‘to throw.’ A four-hundred sentence sample extracted from the Corpus del Español 1900s subcorpus serves as the basis for this study. Statistical tests are used to compare the verbs’ behavior across several factors: morphological markings such as mood, tense and person, the types of subjects (human versus nonhuman), the types of objects (concrete versus nonconcrete), and the interaction of subject and object in full constructions. The tests are accompanied by semantic analysis of the sample sentences. The result of the statistical and descriptive analyses is a radial categorization that highlights the types of metaphoric and metonymic extensions that each verb uses, and where and how the verbs overlap semantically.
Metaphor-metonymies of joy and happiness in Greek
Authors: Theodoropoulou Maria
Published: June 2012

In this paper I examine the idiomatic metonymic expressions denoting joy and happiness in Greek, focusing on their experiential grounding. I first argue for an interdisciplinary approach to the relationship between body, emotion and language, which allows for a holistic perspective to the meaning of these expressions and makes explicit the analogical experiential elements of the particular emotions. As a case study, I look at instances of metaphor within metonymy, which appear to require an interdisciplinary analysis. Drawing on corpus examples, I examine metonymies of joy and happiness with special emphasis on the neurobiological evidence (i.e. the expressive and physiological component of the emotion); the results of the analysis account for how happiness and joy are experienced by the subject.
The situated common-sense knowledge in FunGramKB
Authors: Periñán-Pascual Carlos
Published: June 2012

It has been widely demonstrated that expectation-based schemata, along the lines of Lakoff’s propositional Idealized Cognitive Models, play a crucial role in text comprehension. Discourse inferences are grounded on the shared generalized knowledge which is activated from the situational model underlying the text surface dimension. From a cognitive-plausible and linguistic-aware approach to knowledge representation, FunGramKB stands out for being a dynamic repository of lexical, constructional and conceptual knowledge which contributes to simulate human-level reasoning. The objective of this paper is to present a script model as a carrier of the situated common-sense knowledge required to help knowledge engineers construct more “intelligent” natural language processing systems.
Assessing global marine fishery status with a revised dynamic catch-based method and stock-assessment reference points
Authors: Anderson Sean C. , Branch Trevor A. , Ricard Daniel , Lotze Heike K.
Published: June 2012

Anderson, S. C., Branch, T. A., Ricard, D., and Lotze, H. K. 2012. Assessing global marine fishery status with a revised dynamic catch-based method and stock-assessment reference points. – ICES Journal of Marine Science, 69: . The assessment of fishery status is essential for management, yet fishery-independent estimates of abundance are lacking for most fisheries. Methods exist to infer fishery status from catches, but the most commonly used method is biased towards classifying fisheries as overexploited or collapsed through time and does not account for still-developing fisheries. We introduce a revised method that overcomes these deficiencies by smoothing catch series iteratively, declaring fisheries developing within three years of peak catch, and calibrating thresholds to biological reference points. Compared with status obtained from stock-assessment reference points for 210 stocks, our approach provides a more realistic assessment than the original method, but cannot be perfect because catches are influenced by factors other than biomass. Applied to FAO catches, our method suggests in 2006 32% of global fisheries were developing, 27% fully exploited, 25% overexploited, and 16% collapsed or closed. Although less dire than previous assessments, this still indicates substantial numbers of overexploited stocks. Probably because median exploitation rate decreased since 1992, our catch-based results do not reflect recent stabilization of assessed-stock biomass. Whether this outlook also applies to unassessed stocks can only be revealed with increased or more representative collection of biomass- and exploitation-rate trends.
On the computational content of convergence proofs via Banach limits
Authors: Kohlenbach U. , Leuştean L.
Published: June 2012

This paper addresses new developments in the ongoing proof mining programme, i.e. the use of tools from proof theory to extract effective quantitative information from prima facie ineffective proofs in analysis. Very recently, the current authors developed a method of extracting rates of metastability (as defined by Tao) from convergence proofs in nonlinear analysis that are based on Banach limits and so (for all that is known) rely on the axiom of choice. In this paper, we apply this method to a proof due to Shioji and Takahashi on the convergence of Halpern iterations in spaces
X
with a uniformly Gâteaux differentiable norm. We design a logical metatheorem guaranteeing the extractability of highly uniform rates of metastability under the stronger condition of the uniform smoothness of
X
. Combined with our method of eliminating Banach limits, this yields a full quantitative analysis of the proof by Shioji and Takahashi. We also give a sufficient condition for the computability of the rate of convergence of Halpern iterations.
Formalism and intuition in computability
Authors: Soare Robert Irving
Published: June 2012

The model of recursive functions in 1934–1936 was a deductive formal system. In 1936, Turing and in 1944, Post introduced more intuitive models of Turing machines and generational systems. When they both died prematurely in 1954, their informal approach was replaced again by the very formal KleeneT-predicate for another decade. By 1965, researchers could no longer read the papers. A second wave of intuition arose with the book by Rogers and Lachlan's revealing papers. A third wave of intuition has arisen from 1996 to the present with a return to the original meaning of computability in the sense of Turing and Gödel, and a return of ‘recursive’ to its original meaning of ‘inductive’ and the founding ofComputability in Europeby Cooper and others.
Axiomatizing physical experiments as oracles to algorithms
Authors: Beggs Edwin J. , Costa José Félix , Tucker John V.
Published: June 2012

We developed earlier a theory of combining algorithms with physical systems, on the basis of using physical experiments as oracles to algorithms. Although our concepts and methods are general, each physical oracle requires its own analysis, on the basis of some fragment of physical theory that specifies the equipment and its behaviour. For specific examples of physical systems (mechanical, optical, electrical), the computational power has been characterized using non-uniform complexity classes. The powers of the known examples vary according to assumptions on precision and timing but seem to lead to the same complexity classes, namely

and

. In this study, we develop sets of axioms for the interface between physical equipment and algorithms that allow us to prove general characterizations, in terms of

and

, for large classes of physical oracles, in a uniform way. Sufficient conditions on physical equipment are given that ensure a physical system satisfies the axioms.
A Decrease in Sex Ratio at Birth Nine Months after the Earthquake in L'Aquila
Authors: D'Alfonso A. , Patacchiola F. , Colagrande I. , D'Alessandro G. , Di Fonso A. , Palermo P. , Carta G.
Published: June 2012

Introduction. Multiple factors influence the secondary sex ratio (SSR) including stress, which appears to affect mainly the males born.Objective. We evaluate the effects of the earthquake in L'Aquila on the SSR.Materials and Methods. The SSR for the first six months of 2010 was compared to that of the same period of 2008. The chi-square test and Fisher's test were used for the statistical analysis.Results. Nine months after the earthquake, an important reduction in the SSR was recorded: January 2010 versus January 2008 =0.62 versus 0.96. An overall fall in the SSR was also recorded when the first 3 months of 2010 were compared to the first three months of 2008: 0,82 versus 1,11. When the first three months of 2010 were compared with the second three months of 2010, a statistically significant increase of the sex ratio at birth was noted (0,82 versus 1,27).
Morphology, Geology and Water Quality Assessment of Former Tin Mining Catchment
Authors: Ashraf Muhammad Aqeel , Maah Mohd. Jamil , Yusoff Ismail
Published: June 2012

Bestari Jaya, former tin mining catchment covers an area of 2656.31 hectares comprised of four hundred and forty-two different-size lakes and ponds. The present study area comprise of 92 hectares of the catchment that include four large size lakes. Arc GIS version 9.2 used to develop bathymetric map, Global Positioning System (GPS) for hydrographical survey and flow meter was utilized for water discharge analysis (flow routing) of the catchment. The water quality parameters (pH, temperature, electric conductivity, dissolved oxygen DO, total dissolved solids TDS, chlorides, ammonium, nitrates) were analyzed by using Hydrolab. Quality assurance (QA) and quality control (QC) procedures were strictly followed throughout the field work and data analysis. Different procedures were employed to evaluate the analytical data and to check for possible transcription or dilution errors, changes during analysis, or unusual or unlikely values. The results obtained are compared with interim national water quality standards for Malaysia indicates that water quality of area is highly degraded. It is concluded that Bestri Jaya ex-mining catchment has a high pollution potential due to mining activities and River Ayer Hitam, recipient of catchment water, is a highly polluted river.
Distinct Mechanisms Regulating Gene Expression Coexist within the Fermentative Pathways inChlamydomonas reinhardtii
Authors: Swirsky Whitney Larisa Angela , Novi Giacomo , Perata Pierdomenico , Loreti Elena
Published: June 2012

Under dark anoxia, the unicellular green algaeChlamydomonas reinhardtiimay produce hydrogen by means of its hydrogenase enzymes, in particular HYD1, using reductants derived from the degradation of intercellular carbon stores. Other enzymes belonging to the fermentative pathways compete for the same reductants. A complete understanding of the mechanisms determining the activation of one pathway rather than another will help us engineerChlamydomonasfor fermentative metabolite production, including hydrogen. We examined the expression pattern of the fermentative genesPDC3, LDH1, ADH2, PFL1, andPFR1in response to day-night cycles, continuous light, continuous darkness, and low or high oxygen availability, which are all conditions that vary on a regular basis inChlamydomonas' natural environment. We found that all genes exceptPFL1show daily fluctuations in expression, and thatPFR1differentiated itself from the others in that it is clearly responsive to low oxygen, where asPDC3, LDH1, andADH2are primarily under diurnal regulation. Our results provide evidence that there exist at least three different regulatory mechanisms within the fermentative pathways and suggest that the fermentative pathways are not redundant but rather that availability of a variety of pathways allows for a differential metabolic response to different environmental conditions.
Effects of Hyperbaric Oxygen on Metabolic Capacity of the Skeletal Muscle in Type 2 Diabetic Rats with Obesity
Authors: Fujita Naoto , Nagatomo Fumiko , Murakami Shinichiro , Kondo Hiroyo , Ishihara Akihiko , Fujino Hidemi
Published: June 2012

We investigated whether hyperbaric oxygen enhances the oxidative metabolic capacity of the skeletal muscle and attenuates adipocyte hypertrophy in type 2 diabetic rats with obesity. Five-week-old male Otsuka Long-Evans Tokushima fatty (OLETF) and Long-Evans Tokushima Otsuka (LETO) rats were used as diabetic animals and nondiabetic controls, respectively, and assigned to control and hyperbaric oxygen groups. Animals in the hyperbaric oxygen group were exposed to an atmospheric pressure of 1.25 with an oxygen concentration of 36% for 3 h daily. The glucose level at 27 weeks of age was significantly higher in OLETF rats than in LETO rats, but the elevation was inhibited in OLETF rats exposed to hyperbaric oxygen. The slow-to-fast fiber transition in the skeletal muscle was observed in OLETF rats, but the shift was inhibited in OLETF rats exposed to hyperbaric oxygen. Additionally, the oxidative enzyme activity of muscle fibers was increased by hyperbaric oxygen. The adipocyte size was larger in OLETF rats than in LETO rats, but hypertrophied adipocytes were not observed in OLETF rats exposed to hyperbaric oxygen. Hyperbaric oxygen enhances glucose and lipid metabolism in the skeletal muscle, indicating that hyperbaric oxygen can prevent elevation of glucose and adipocyte hypertrophy in diabetic rats with obesity.
Phenotypic Detection of Metallo-β-Lactamase in Imipenem-ResistantPseudomonas aeruginosa
Authors: Khosravi Yalda , Loke Mun Fai , Chua Eng Guan , Tay Sun Tee , Vadivelu Jamuna
Published: June 2012

Carbapenems are the primary choice of treatment for severePseudomonas aeruginosainfection. However, the emergence of carbapenem resistance due to the production of metallo-β-lactamases (MBLs) is of global concern. In this study, 90 imipenem- (IPM- or IP-) resistantP. aeruginosa(IRPA) isolates, including 32 previously tested positive and genotyped for MBL genes by PCR, were subjected to double-disk synergy test (DDST), combined disk test (CDT), and imipenem/imipenem-inhibitor (IP/IPI)E-test to evaluate their MBLs detection capability. All three methods were shown to have a sensitivity of 100%. However, DDST was the most specific of the three (96.6%), followed by IP/IPIE-test interpreted based on the single criteria of IP/IPI≥8as positive (62.1%), and CDT was the least specific (43.1%). Based on the data from this evaluation, we propose that only IRPA with IP MIC>16 μg/mL and IP/IPI≥8by IP/IPIE-test should be taken as positive for MBL activity. With the new dual interpretation criteria, the MBL IP/IPIE-test was shown to achieve 100% sensitivity as well as specificity for the IRPA in this study. Therefore, the IP/IPIE-test is a viable alternative phenotypic assay to detect MBL production in IRPA in our population in circumstances where PCR detection is not a feasible option.
Characteristics, Management, and In-Hospital Outcomes of Diabetic Patients with Acute Coronary Syndrome in the United Arab Emirates
Authors: Shehab Abdulla , Al-Dabbagh Bayan , Almahmeed Wael , Bustani Nazar , Agrawal Amrish , Yusufali Afzal , Wassef Adel , Alnaeemi Abdulla , Alsheikh-Ali Alawi A.
Published: June 2012

We describe the baseline characteristics, management, and in-hospital outcomes of patients in the United Arab Emirates (UAE) with DM admitted with an acute coronary syndrome (ACS) and assess the influence of DM on in-hospital mortality. Data was analyzed from 1697 patients admitted to various hospitals in the UAE with a diagnosis of ACS in 2007 as part of the 1st Gulf RACE (Registry of Acute Coronary Events). Of 1697 patients enrolled, 668 (39.4%) were diabetics. Compared to patients without DM, diabetic patients were more likely to have a past history of coronary artery disease (49.1% versus 30.1%,P<0.001), hypertension (67.2% versus 36%,P<0.001), and prior revascularization (21% versus 11.4%,P<0.001). They experienced more in-hospital recurrent ischemia (8.5% versus 5.1%;P=0.004) and heart failure (20% versus 10%;P<0.001). The mortality rate was 2.7% for diabetics and 1.6% for nondiabetics (P=0.105). After age adjustment, in-hospital mortality increased by 3.5% per year of age (P=0.016). This mortality was significantly higher in females than in males (P=0.04). ACS patients with DM have different clinical characteristics and appear to have poorer outcomes.
Development and Validation of an RP-HPLC Method for CB13 Evaluation in Several PLGA Nanoparticle Systems
Authors: Álvarez-Fuentes J. , Martín-Banderas L. , Muñoz-Rubio I. , Holgado M. A. , Fernández-Arévalo M.
Published: June 2012

A simple, fast, and reversed-phase high-performance liquid chromatographic (RP-HPLC) method has been developed and validated for determining of a cannabinoid derivate, which displays potent antihyperalgesic activity, 1-naphthalenyl[4-(pentyloxy)-1-naphthalenyl]methanone (CB13) into PLGA nanoparticles. Separation was achieved in a C18 column using a mobile phase consisting of two solvents: solvent A, consisting of acetonitrile : water : acetic acid (75 : 23.7 : 1.3 v/v), and solvent B, consisting of acetonitrile. An isocratic method (70 : 30 v/v), with a flow rate of 1.000 mL/min, and a diode array detector were used. The developed method was precise, accurate, and linear over the concentration range of analysis with a limit of detection and a limit of quantification of 0.5 and 1.25 μg/mL, respectively. The developed method was applied to the analysis of CB13 in nanoparticles samples obtained by three different procedures (SEV, FF, and NPP) in terms of encapsulation efficiency and drug release. Nanoparticles size and size distribution were also evaluated founding that NPP method presented the most lowest particle sizes with narrow-size distribution (≈320 nm) and slightly negative zeta potential (≈−25 mV) which presumes a suitable procedure for the synthesis of PLGA-CB13 nanoparticles for oral administration.
The Association between Single-Nucleotide Polymorphisms ofORAI1Gene and Breast Cancer in a Taiwanese Population
Authors: Chang Wei-Chiao , Woon Peng Yeong , Hsu Yu-Wen , Yang Shengyu , Chiu Yi-Ching , Hou Ming Feng
Published: June 2012

Background. Breast cancer is the most common malignancy in women. There is increasing evidence suggesting thatORAI1, components of store-operated calcium channel, play a pivotal role in breast cancer progression and metastasis.Methods. A total of 384 female patients with breast cancer were included in this study. We selected five representative taggingORAI1SNPs from HapMap database with minimum allele frequency (MAF)>10%. Genotyping was performed using TaqMan allelic discrimination assay. Chi-square (χ2) test was used to analyze statistical differences among control and patient groups in genotype and allelic frequencies.Results. Two of theORAI1SNPs (rs12320939 and rs12313273) were associated with estrogen receptors positive in breast cancer patients under the recessive model. When the Bonferroni correction was performed, the significance still existed. In addition, rs12320939 also associated with the lymph nodal involvement.Conclusion. We showed that genetic polymorphisms ofORAI1associated strongly with lymph nodal involvement and estrogen receptors (ERs) positive breast cancer patients in a Taiwanese population.
Ki-67 and MCM-2 in Dental Follicle and Odontogenic Cysts: The Effects of Inflammation on Proliferative Markers
Authors: Güler Nurhan , Çomunoğlu Nil , Cabbar Fatih
Published: June 2012

The aim of this study was to investigate whether there is any association between inflammation and the expression of markers of cell cycle entry (Ki-67 and MCM-2) in dental follicle (DF) of asymptomatic impacted teeth and odontogenic cysts. The study consisted of 70 DFs and 20 odontogenic cysts (radicular cyst (RC), dentigerous cyst (DC) and keratocytic odontogenic tumor (KCOT) located at posterior mandibular region. Histological findings of inflammation for all specimen and mucous cell prosoplasia, squamous metaplasia, glandular epithelium for all DFs were stained with hematoxyline and eosin, periodic acid schiff, alcian blue, and mucin. Epithelial cell proliferation was determined by using immunohistochemical labeling for Ki-67 and MCM-2. The histologic examinations showed 16% mucous cell prosoplasia, 54% squamous metaplasia, 20% glandular epithelium, 37% inflammation. Inflammation was detected in all RCs and %62 in DF, %43 in DC and KCOT. Positive correlation was found between the inflammation of DF and odontogenic cysts (P<0.01). The mean Ki-67 and MCM-2 expressions were found9,64±5,99and6,34±3,81in DF,11,85±9,01and13,6±9,94in odontogenic cysts, respectively. While the mean Ki-67 expressions were statistically significant in DF and KCOT (P<0.01), MCM-2 were significant in RC and KCOT (P<0.01). MCM-2 expresion in RCs were statistically significant than KCOT (P<0.01). The results of this study indicated that the higher MCM-2 expressions in RC than the KCOT might be related to the inflammation and this protein might be more sensitive to inflammation.
Competing intermolecular interactions in some `bridge-flipped' isomeric phenylhydrazones
Authors: Ojala William H. , Arola Trina M. , Brigino Ann M. , Leavell Jeremy D. , Ojala Charles R.
Published: June 2012

To examine the roles of competing intermolecular interactions in differentiating the molecular packing arrangements of some isomeric phenylhydrazones from each other, the crystal structures of five nitrile–halogen substituted phenylhydrazones and two nitro–halogen substituted phenylhydrazones have been determined and are described here: (E)-4-cyanobenzaldehyde 4-chlorophenylhydrazone, C14H10ClN3, (Ia); (E)-4-cyanobenzaldehyde 4-bromophenylhydrazone, C14H10BrN3, (Ib); (E)-4-cyanobenzaldehyde 4-iodophenylhydrazone, C14H10IN3, (Ic); (E)-4-bromobenzaldehyde 4-cyanophenylhydrazone, C14H10BrN3, (IIb); (E)-4-iodobenzaldehyde 4-cyanophenylhydrazone, C14H10IN3, (IIc); (E)-4-chlorobenzaldehyde 4-nitrophenylhydrazone, C13H10ClN3O2, (III); and (E)-4-nitrobenzaldehyde 4-chlorophenylhydrazone, C13H10ClN3O2, (IV). Both (Ia) and (Ib) are disordered (less than 7% of the molecules have the minor orientation in each structure). Pairs (Ia)/(Ib) and (IIb)/(IIc), related by a halogen exchange, are isomorphous, but none of the `bridge-flipped' isomeric pairs,viz.(Ib)/(IIb), (Ic)/(IIc) or (III)/(IV), is isomorphous. In the nitrile–halogen structures (Ia)–(Ic) and (IIb)–(IIc), only the bridge N—H group and not the bridge C—H group acts as a hydrogen-bond donor to the nitrile group, but in the nitro–halogen structures (III) (withZ′ = 2) and (IV), both the bridge N—H group and the bridge C—H group interact with the nitro group as hydrogen-bond donors, albeitviadifferent motifs. The occurrence here of the bridge C—H contact with a hydrogen-bond acceptor suggests the possibility that other pairs of `bridge-flipped' isomeric phenylhydrazones may prove to be isomorphous, regardless of the change from isomer to isomer in the position of the N—H group within the bridge.
Amplification of all 11 RNA segments of group A rotaviruses based on reverse transcription polymerase chain reaction
Authors: Fujii Yoshiki , Shimoike Takashi , Takagi Hirotaka , Murakami Kosuke , Todaka‐Takai Reiko , Park YoungBin , Katayama Kazuhiko
Published: June 2012

Group A rotaviruses (RVA) are a major cause of acute infantile gastroenteritis. The viral genome comprises 11 double‐stranded RNA segments and the respective gene segments are classified into more than eight genotypes, according to the nucleotide sequence similarities. So far, it has been difficult to amplify full‐length sequences of long RNA segments of rotaviruses by one‐time only RT‐PCR (especially in the genes for the viral proteins VP1, VP2, VP3 and VP4). In this study, a set of universal primers to amplify all 11 segments of RVA was designed by aligning the nucleotide sequences of the typical rotavirus strains. Using these primers and a high‐fidelity and rapid DNA polymerase in a one‐step reverse transcription polymerase chain reaction, almost the entire length of all 11 segments of the seven rotavirus strains Wa, DS‐1, Hochi, 69M, WI61, M37 and SA11‐S1 were accurately and rapidly amplified. In addition, all 11 segments of rotavirus obtained from a fecal specimen were successfully amplified. In conclusion, the method described here will be useful as an RVA detection system and protocol for complete analysis of the 11 genome sequences.
An attenuated mutant of avian pathogenic Escherichia coli serovar O78: a possible live vaccine strain for prevention of avian colibacillosis
Authors: Nagano Tetsuji , Kitahara Rie , Nagai Shinya
Published: June 2012

Here construction of an attenuated mutant of an avian pathogenic Escherichia coli serovar O78 using an allelic exchange procedure is described. The mutant AESN1331, which carries a deletion in the crp gene, lost tryptophan deaminase activity and therefore lacked the ability to produce indole. The mutant strain additionally lacked the ability to adsorb Congo red, no longer fermented sugars other than glucose and L‐arabinose, did not harbor four known virulence‐associated genes (iss, tsh, cvaA, papC), and was susceptible to many antimicrobials, with the exception of nalidixic acid. The lethal dose (LD50 value) of the mutant strain on intravenous challenge in chickens was approximately 10‐fold higher than that of the parent strain. Additionally, the mutant strain was rapidly eliminated from chickens, being detected in the respiratory tract only on the first day post‐inoculation by fine spray. Administration of the mutant strain via various routes such as spray and eye drop for chickens, as well as in ovo inoculation for embryonated egg, evoked an effective immune response that protected against a virulent wild‐type E. coli O78 strain. Specifically, after immunization with the mutant strain, chickens challenged intravenously with an E. coli O78 strain exhibited decreases in mortality, clinical scores, organ lesion scores, and recovery of the challenge strain from organs compared to non‐immunized chickens. These findings suggest that AESN1331 is a suitable candidate for a live vaccine strain to protect chickens from colibacillosis caused by avian E. coli O78.
Gene expression profile of early in vitro biofilms of Streptococcus pneumoniae
Authors: Yadav Mukesh Kumar , Kwon Seong Keun , Cho Chang Gun , Park Seok‐Won , Chae Sung‐Won , Song Jae‐Jun
Published: June 2012

In this study, the gene expression profile of early in vitro Streptococcus pneumoniae biofilm with respect to planktonic cells in cDNA microarray analysis is reported. Microarray analysis with respect to planktonic cells was performed on total RNA extracted from biofilms grown in 24‐well microtiter plates. To validate the microarray results, real‐time RT‐PCR was performed on 13 differentially expressed genes and one constitutively expressed gene. The cDNA‐microarray analyses identified 89 genes that were significantly differentially expressed in biofilm and planktonic cells. Genes involved in isoprenoid biosynthesis, cell wall biosynthesis, translation and purine and pyrimidine nucleotide metabolic pathways were exclusively expressed in the biofilms, whereas transcription regulator genes were exclusively expressed in planktonic cells. The real‐time RT‐PCR results of 13 differentially regulated genes were completely in agreement with the microarray data. The exclusive up regulation in biofilms of genes involved in the mevalonate pathway, cell wall biosynthesis, translation and purine and pyrimidine nucleotide metabolic pathways suggests that expression of these genes may be required for initial biofilm formation, and growth and survival of bacteria in biofilms. The up regulation of related genes suggests that cells in biofilms may be under stress conditions and possibly actively involved in the protein synthesis required to adapt to a new environment.
Role of JC virus agnoprotein in virion formation
Authors: Suzuki Tadaki , Semba Shingo , Sunden Yuji , Orba Yasuko , Kobayashi Shintaro , Nagashima Kazuo , Kimura Takashi , Hasegawa Hideki , Sawa Hirofumi
Published: June 2012

JC virus (JCV) belongs to the polyomavirus family of double‐stranded DNA viruses and causes progressive multifocal leukoencephalopathy in humans. JCV encodes early proteins (large T antigen, small T antigen, and T′ antigen) and four late proteins (agnoprotein, and three viral capsid proteins, VP1, VP2, and VP3). In the current study, a novel function for JCV agnoprotein in the morphogenesis of JC virion particles was identified. It was found that mature virions of agnoprotein‐negative JCV are irregularly shaped. Sucrose gradient sedimentation and cesium chloride gradient ultracentrifugation analyses revealed that the particles of virus lacking agnoprotein assemble into irregularly sized virions, and that agnoprotein alters the efficiency of formation of VP1 virus‐like particles. An in vitro binding assay and immunocytochemistry revealed that agnoprotein binds to glutathione S‐transferase fusion proteins of VP1 and that some fractions of agnoprotein colocalize with VP1 in the nucleus. In addition, gel filtration analysis of formation of VP1‐pentamers revealed that agnoprotein enhances formation of these pentamers by interacting with VP1. The present findings suggest that JCV agnoprotein plays a role, similar to that of SV40 agnoprotein, in facilitating virion assembly.
A multicentre observational study of intra‐operative ventilatory management during general anaesthesia: tidal volumes and relation to body weight
Authors: Jaber S. , Coisel Y. , Chanques G. , Futier E. , Constantin J.‐M. , Michelet P. , Beaussier M. , Lefrant J.‐Y. , Allaouchiche B. , Capdevila X. , Marret E.
Published: June 2012

We conducted an observational prospective multicenter study to describe the practices of mechanical ventilation, to determine the incidence of use of large intra‐operative tidal volumes (≥ 10 ml.kg−1 of ideal body weight) and to identify patient factors associated with this practice. Of the 2960 patients studied in 97 anaesthesia units from 49 hospitals, volume controlled mode was the most commonly used (85%). The mean (SD) tidal volume was 533 (82) ml; 7.7 (1.3) ml.kg−1 (actual weight) and 8.8 (1.4) ml.kg−1 (ideal body weight)). The lungs of 381 (18%) patients were ventilated with a tidal volume > 10 ml.kg−1 ideal body weight. Being female (OR 5.58 (95% CI 4.20–7.43)) and by logistic regression, underweight (OR 0.06 (95% CI 0.01–0.45)), overweight (OR 1.98 (95% CI 1.49–2.65)), obese (OR 5.02 (95% CI 3.51–7.16)), severely obese (OR 10.12 (95% CI 5.79–17.68)) and morbidly obese (OR 14.49 (95% CI 6.99–30.03)) were the significant (p ≤ 0.005) independent factors for the use of large tidal volumes during anaesthesia.
Psychological adjustment among left‐behind children in rural China: the role of parental migration and parent–child communication
Authors: Su S. , Li X. , Lin D. , Xu X. , Zhu M.
Published: June 2012

Background

Left‐behind children refer to those rural children who are under 18 years of age and are left at home when both or one of their parents migrate to urban area for work. Recent findings showed that left‐behind children were disadvantaged by developmental, emotional and social problems.

Method

A sample of 1165 rural children and adolescents were recruited to examine the characteristics of left‐behind children and explore the differences in psychological adjustment (including satisfaction, loneliness and happiness) by patterns of parental migration (i.e. no parent migrating, one parent migrating or two parents migrating) and the level of parent–child communication in rural China.

Results

(1) Compared with children with one parent migrating, children with two parents migrating were separated from their parents at younger ages, for longer periods, and saw their migrant parents less frequently. (2) Children with two parents migrating reported the lowest level of satisfaction among the three groups of rural children. Both groups of children with one or two parents migrating experienced more loneliness compared with children with no parent migrating. There were no significant differences in school satisfaction and happiness among the three groups. (3) The children who reported a higher level of parent–child communication also reported a higher level of life and school satisfaction and happiness, and no differences in loneliness were found by levels of parent–child communication.

Conclusions

These results indicate that loneliness was the most common and important experience of left‐behind children. Parent–child communication is important for the development of all rural children, including those who were left behind by their migrant parents.