bluuebunny/crossref_metadata_2025 huggingface dataset:
Antimycobacterial Effect of Extract and Its Components from Rheum rhaponticum
Authors: Smolarz Helena Danuta , Swatko-Ossor Marta , Ginalska Grażyna , Medyńska Ewa
Published: February 2013

The global threat of tuberculosis demands the search for alternative antimycobacterial drugs. The present study examined roots and petioles from Rheum rhaponticum for antimycobacterial activity. Crude methanol extracts and eight phenolic compounds isolated by preparative column chromatography were tested against Mycobacterium tuberculosisH37Ra and M. bovis using the broth dilution method. The extract from roots and its components, such as rhaponticin, deoxyrhaponticin, resveratrol, barbaloin, aloe-emodin, and chrysophanol were found to have antimycobacterial activity against both microorganisms. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration of all the investigated samples ranged from 32 to 512 μg/mL. The anthracene derivatives were the most active; their MICs were 32, 64, and 64 μg/mL (M. tuberculosisH37Ra) and 128, 64, and 64 μg/mL (M. bovis), respectively. The microorganisms were resistant to stimulation with extract from petioles, as were quercetin and rutin. The results showed that anthracene and stilbene derivatives play a prominent role in the antimycobacterial properties of R. rhaponticum.
Quality Control for Federal Clean Water Act and Safe Drinking Water Act Regulatory Compliance
Authors: Askew Ed
Published: February 2013

QC sample results are required in order to have confidence in the results from analytical tests. Some of the AOAC water methods include specific QC procedures, frequencies, and acceptance criteria. These are considered to be the minimum controls needed to perform the method successfully. Some regulatory programs, such as those in 40 CFR Part 136.7, require additional QC or have alternative acceptance limits. Essential QC measures include method calibration, reagent standardization, assessment of each analyst's capabilities, analysis of blind check samples, determination of the method's sensitivity (method detection level or quantification limit), and daily evaluation of bias, precision, and the presence of laboratory contamination or other analytical interference. The details of these procedures, their performance frequency, and expected ranges of results are set out in this manuscript. The specific regulatory requirements of 40 CFR Part 136.7 for the Clean Water Act, the laboratory certification requirements of 40 CFR Part 141 for the Safe Drinking Water Act, and the ISO 17025 accreditation requirements under The NELAC Institute are listed.
Bioreactors: Rotating Biological Contactors
Authors: Cortez Susana , Teixeira Pilar , Oliveira Rosário , Mota Manuel
Published: February 2013

Rotating biological contactors (RBCs) have been used as an efficient fixed film method of treating wastewater due to its advantages such as low energy and land requirements or simplicity of operation. In this article, we firstly describe the operation, benefits and drawbacks, hydrodynamics and typical applications of these bioreactors, and then review the main factors affecting their performance. Some aspects about RBC design and scale‐up, the main operational problems and their resolution are presented. The comparison of the performance of RBCs with other wastewater treatment systems as well as costs considerations and prospects are also discussed.
Process Analytical Technology: Strategies for Biopharmaceuticals
Authors: S. Rathore Anurag , Kapoor Gautam
Published: February 2013

In recent times, there is a growing need in the biopharmaceutical industry for improved process understanding to enhance productivity and product quality. Process Analytical Technology (PAT) is a system for designing, analyzing and controlling manufacturing processes based on an understanding of the engineering and scientific principles involved and identification of variables that affect product quality. It is based on the US FDA's belief that: “quality cannot be tested into products; it should be built‐in or should be by design.” This article provides the reader with an overview of the evolution of this technology, its key benefits and the challenges faced in its implementation. It then explains how PAT can be applied to a typical biopharmaceutical manufacturing process involving upstream and downstream processing, drug product manufacturing and chemometrics.
Unraveling Bright Molecule‐Like State and Dark Intrinsic State in Green‐Fluorescence Graphene Quantum Dots via Ultrafast Spectroscopy
Authors: Wang Lei , Zhu Shou‐Jun , Wang Hai‐Yu , Wang Ya‐Feng , Hao Ya‐Wei , Zhang Jun‐Hu , Chen Qi‐Dai , Zhang Yong‐Lai , Han Wei , Yang Bai , Sun Hong‐Bo
Published: February 2013

Graphene quantum dots (GQDs) have recently emerged as a promising type of low‐toxicity, high‐biocompatibility, and chemically inert fluorescence probe with a high resistance to photobleaching. They are a prospective substitution for organic materials in light‐emitting devices (LED), enabling the predicted concept of much brighter and more robust carbon LED (CLED). However, the mechanism of GQD emission remains an open problem despite extensive studies conducted so far, which is becoming the greatest obstacle in the route of technical improvement of GQD quantum efficiency. This problem is solved by the combined usage of femtosecond transient absorption spectroscopy and femtosecond time‐resolved fluorescence dynamics measured by a fluorescence upconversion technique, as well as a nanosecond time‐correlated single‐photon counting technique. A fluorescence emission‐associated dark intrinsic state due to the quantum confinement of in‐plane functional groups is found in green‐fluorescence graphene quantum dots by the ultrafast dynamics study, and the two characteristic fluorescence peaks that appear in all samples are attributed to independent molecule‐like states. This finding establishes the correlation between the quantum confinement effect and molecule‐like emission in the unique green‐fluorescence graphene quantum dots, and may lead to innovative technologies of GQD fluorescence enhancement, as well as its broad industrial application.
Differences in Innovation Between Food and Manufacturing Firms: An Analysis of Persistence
Authors: Triguero Ángela , Córcoles David , Cuerva María C.
Published: February 2013

The authors examine the differences in the behavior of the innovation between the Spanish agrifood and manufacturing firms using firm‐level data from 1990–2008 to analyze the persistence in innovation and to explore the explanatory determinants of the probability of being product and process innovator. Survival functions, transition probability matrices, and dynamic discrete choice panel data models are combined to measure persistence. The results suggest that in the food industry the persistence of process innovation is higher than in product innovation. Environmental and market determinants such as market changes or appropriability are more decisive to explain innovation in food industry. By contrast, several determinant variables for innovation activities in the manufacturing sector seem not to be linked with the innovation in food firms. That is the case of the outsourcing ratio and the positive evolution of market share of the individual firm.
Non‐invasive UPR monitoring system and its applications in CHO production cultures
Authors: Du Zhimei , Treiber David , McCoy Rebecca E. , Miller Amanda K. , Han Mei , He Feng , Domnitz Sarah , Heath Carole , Reddy Pranhitha
Published: February 2013

Unfolded protein response (UPR) is the primary signaling network activated in response to the accumulation of unfolded and/or misfolded protein in the endoplasmic reticulum (ER). The expression of high levels of recombinant proteins in mammalian cell cultures has been linked to the increased UPR. However, the dynamics of different UPR‐mediated events and their impact on cell performance and recombinant protein secretion during production remain poorly defined. Here, we have created a non‐invasive UPR‐responsive, fluorescence‐based reporter system to detect and quantify specific UPR‐mediated transcriptional activation of different intracellular signaling pathways. We have generated stable antibody‐expressing CHO clones containing this UPR responsive system and established FACS‐based methods for real‐time, continuous monitoring of the endogenous UPR activation in live cultures. The results showed that the UPR activation is dynamically regulated during production culture. The clones differed in their UPR patterns; both the timing and the degree of UPR‐induced transcriptional activation were linked to cell performance, such as growth, and viability. In addition, the cell culture environment, such as media composition and osmolarity, significantly impacted endogenous UPR activation. Taken together, these data demonstrate a utility of this UPR monitoring system in recombinant protein production processes and the observations increase our understanding of the critical role of UPR in regulating diverse phenotypes of the cells including growth, survival and recombinant protein secretion under different culture environments and processing conditions. Biotechnol. Bioeng. 2013; 110: 2184–2194. © 2013 Wiley Periodicals, Inc.
Highly Sensitive and Selective Basal Plane Pyrolytic Graphite Electrode Modified with 1,4‐Naphthoquinone/MWCNT for Simultaneous Determination of Dopamine, Ascorbate and Urate
Authors: Oliveira Ananda Xavier , Silva Saimon Moraes , Leite Fernando Roberto Figueiredo , Kubota Lauro Tatsuo , Damos Flavio Santos , de Cássia Silva Luz Rita
Published: February 2013

The present work describes the development of a highly selective and sensitive voltammetric sensor for dopamine (DA), ascorbic acid (AA) and uric acid (UA) using a basal plane pyrolytic graphite (BPPG) electrode modified with 1,4‐naphthoquinone (NQ) adsorbed on multiwalled carbon nanotubes (MWCNT). The modified electrode showed an excellent electrochemical activity towards the oxidations of DA, AA and UA. Three well‐defined voltammetric peaks, in a buffered solution at pH 7.5, were obtained by differential pulse voltammetry (DPV) at −0.050, 0.145 and 0.270 V vs. Ag/AgCl for AA, DA and UA, respectively. Linear calibration plots were obtained in the range of 10–70 nmol L−1 for DA, 40–280 µmol L−1 for AA and 2–14 µmol L−1 for UA, with detection limits of 3 nmol L−1, 1.9 µmol L−1 and 0.1 µmol L−1, respectively. The sensor was successfully applied in human urine samples and the results showed that the modified electrode has no interferences from urine sample.
Electrochemical Behavior of Caffeic Acid Assayed with Gold Nanoparticles/Graphene Nanosheets Modified Glassy Carbon Electrode
Authors: Zhang Yanli , Liu Yanpei , He Jiemei , Pang Pengfei , Gao Yuntao , Hu Qiufen
Published: February 2013

A gold nanoparticle (AuNP) and graphene nanosheet (GN) modified glassy carbon electrode (GCE) is proposed as voltammetric sensor for caffeic acid assay. The sensor exhibits a surface‐confined and reversible process for oxidation of caffeic acid revealed by cyclic voltammetry. The results show more favorable electron transfer kinetics than the bare GCE. The linear response of the sensor is from 5×10−7 to 5×10−5 M with a detection limit of 5×10−8 M (S/N=3). The AuNP/GN nanocomposite shows more favorable electrochemical activity and should be a kind of more robust and advanced functional material, which provides a promising platform for electrochemical sensors and biosensors. The method was successfully applied to detect caffeic acid in pharmaceutical tablets with satisfactory results.
Confounding effects of coral growth and high SST variability on skeletal Sr/Ca: Implications for coral paleothermometry
Authors: Grove Craig A. , Kasper Sebastian , Zinke Jens , Pfeiffer Miriam , Garbe‐Schönberg Dieter , Brummer Geert‐Jan A.
Published: February 2013

Massive corals offer continuous records of climate locked within their skeleton, with the most commonly applied paleo‐thermometer being Sr/Ca. Recently, however, problems with Sr/Ca thermometry indicate that the intrinsic variance of single‐core Sr/Ca time series differs between cores. Here, we compare the Sr/Ca records and growth parameters of two Porites lutea colonies sampled from the same reef zone, 0.72 km apart, with two gridded SST datasets, ERSST and HadISST, off NE Madagascar. Specifically, we address seasonal and interannual variability as well as trend differences between records over the same 43 year period. The two gridded SST datasets showed strong seasonality and weak positive ENSO anomalies on a slow 43 year warming trend at significantly different rates. Both the coral Sr/Ca records showed the same clear seasonality and similar amplitudes in SST. However, on interannual timescales, they displayed diverging 43 year Sr/Ca trends and opposite responses to weak ENSO anomalies. Moreover, their growth response also differed as one coral showed increasing extension/calcification rates and Sr/Ca ratios (cooling) over the 43 years, while the other coral showed decreasing extension/calcification rates and Sr/Ca ratios (warming). Further, during positive ENSO events, the calcification rates of the two corals were negatively correlated, while skeletal density anomalies were opposite. Possible explanations to why these corals are so different may be related to the corals growth response to SST changes. The growth response of individual corals to increasing SST seems to be opposite, which in turn are likely related to biological factors. Consequently, coral growth responses explain much of the inter‐colony Sr/Ca variability.
Linking NO2 surface concentration and integrated content in the urban developed atmospheric boundary layer
Authors: Dieudonné E. , Ravetta F. , Pelon J. , Goutail F. , Pommereau J.‐P.
Published: February 2013

A statistical linear relationship between NO2 surface concentration and its integrated content in the atmospheric boundary layer (ABL) is established in urban conditions, using ABL depth as an ancillary parameter. This relationship relies on a unique data set including 20 months of observations from a ground‐based UV‐visible light spectrometer and from an aerosol lidar, both located in Paris inner city center. Measurements show that in all seasons, large vertical gradients of NO2 concentration exist in Paris developed ABL, explaining why the average concentration retrieved is only about 25% of NO2 surface concentration. This result shows that the commonly used hypothesis of constant mixing ratio in the ABL is not valid over urban areas, where large NOx emissions occur. Moreover, the relationship obtained is robust, and the studied area lacks of any particular orographic features, so that our results should be more widely applicable to pollution survey from space‐borne observations.
Coevolution of nonlinear trends in vegetation, soils, and topography with elevation and slope aspect: A case study in the sky islands of southern Arizona
Authors: Pelletier Jon D. , Barron‐Gafford Greg A. , Breshears David D. , Brooks Paul D. , Chorover Jon , Durcik Matej , Harman Ciaran J. , Huxman Travis E. , Lohse Kathleen A. , Lybrand Rebecca , Meixner Tom , McIntosh Jennifer C. , Papuga Shirley A. , Rasmussen Craig , Schaap Marcel , Swetnam Tyson L. , Troch Peter A.
Published: February 2013

Feedbacks among vegetation dynamics, pedogenesis, and topographic development affect the “critical zone”—the living filter for Earth's hydrologic, biogeochemical, and rock/sediment cycles. Assessing the importance of such feedbacks, which may be particularly pronounced in water‐limited systems, remains a fundamental interdisciplinary challenge. The sky islands of southern Arizona offer an unusually well‐defined natural experiment involving such feedbacks because mean annual precipitation varies by a factor of five over distances of approximately 10 km in areas of similar rock type (granite) and tectonic history. Here we compile high‐resolution, spatially distributed data for Effective Energy and Mass Transfer (EEMT: the energy available to drive bedrock weathering), above‐ground biomass, soil thickness, hillslope‐scale topographic relief, and drainage density in two such mountain ranges (Santa Catalina: SCM; Pinaleño: PM). Strong correlations exist among vegetation‐soil‐topography variables, which vary nonlinearly with elevation, such that warm, dry, low‐elevation portions of these ranges are characterized by relatively low above‐ground biomass, thin soils, minimal soil organic matter, steep slopes, and high drainage densities; conversely, cooler, wetter, higher elevations have systematically higher biomass, thicker organic‐rich soils, gentler slopes, and lower drainage densities. To test if eco‐pedo‐geomorphic feedbacks drive this pattern, we developed a landscape evolution model that couples pedogenesis and topographic development over geologic time scales, with rates explicitly dependent on vegetation density. The model self‐organizes into states similar to those observed in SCM and PM. Our results highlight the potential importance of eco‐pedo‐geomorphic feedbacks, mediated by soil thickness, in water‐limited systems.
Runoff generation and soil erosion processes after clear cutting
Authors: Mohr Christian H. , Coppus Ruben , Iroumé Andrés , Huber Anton , Bronstert Axel
Published: February 2013

Timber harvesting by clear cutting is known to impose environmental impacts, including severe disturbance of the soil hydraulic properties which intensify the frequency and magnitude of surface runoff and soil erosion. However, it remains unanswered if harvest areas act as sources or sinks for runoff and soil erosion and whether such behavior operates in a steady state or evolves through time. For this purpose, 92 small‐scale rainfall simulations of different intensities were carried out under pine plantation conditions and on two clear‐cut harvest areas of different age. Nonparametrical Random Forest statistical models were set up to quantify the impact of environmental variables on the hydrological and erosion response. Regardless of the applied rainfall intensity, runoff always initiated first and yielded most under plantation cover. Counter to expectations, infiltration rates increased after logging activities. Once a threshold rainfall intensity of 20 mm/h was exceeded, the younger harvest area started to act as a source for both runoff and erosion after connectivity was established, whereas it remained a sink under lower applied rainfall intensities. The results suggest that the impact of microtopography on surface runoff connectivity and water‐repellent properties of the topsoil act as first‐order controls for the hydrological and erosion processes in such environments. Fast rainfall‐runoff response, sediment‐discharge‐hystereses, and enhanced postlogging groundwater recharge at catchment scale support our interpretation. At the end, we show the need to account for nonstationary hydrological and erosional behavior of harvest areas, a fact previously unappreciated in predictive models.
In‐line turbidity monitoring of the second phase droplets deformation during extrusion
Authors: Zborowski L. , Canevarolo S.V.
Published: February 2013

The dispersion and deformation of the second phase during extrusion of polymer mixtures were in real‐time characterized using an in‐line turbidimeter. Three polymer mixtures with constant concentration but very different viscosity ratios (1/4, 1, and 4) were reprocessed up to three times in a twin‐screw extruder. After that they were processed again, having the extruder exit being blocked by an on/off valve, which controls the hold‐on and discharge. The melt turbidity, a variable dependent of the droplets size and shape, was recorded during processing and controlled die‐head pressure discharge. The deformation of the droplets is high and reversible in mixture having viscosity ratio close to 1, indicating no droplet breakup and/or coalescence. In contrast, for high viscosity ratios and high matrix elasticity a hysteresis is formed during deformation/recovery of the droplets. POLYM. ENG. SCI., 53:2422–2428, 2013. © 2013 Society of Plastics Engineers
Rapid differentiation of isomeric lipids by photodissociation mass spectrometry of fatty acid derivatives
Authors: Pham Huong T. , Trevitt Adam J. , Mitchell Todd W. , Blanksby Stephen J.
Published: February 2013

RATIONALE

Both traditional electron ionization and electrospray ionization tandem mass spectrometry have demonstrated limitations in the unambiguous identification of fatty acids. In the former case, high electron energies lead to extensive dissociation of the radical cations from which little specific structural information can be obtained. In the latter, conventional collision‐induced dissociation (CID) of even‐electron ions provides little intra‐chain fragmentation and thus few structural diagnostics. New approaches that harness the desirable features of both methods, namely radical‐driven dissociation with discrete energy deposition, are thus required.

METHODS

Herein we describe the derivatization of a structurally diverse suite of fatty acids as 4‐iodobenzyl esters (FAIBE). Electrospray ionization of these derivatives in the presence of sodium acetate yields abundant [M + Na]+ ions that can be mass‐selected and subjected to laser irradiation (λ = 266 nm) on a modified linear ion‐trap mass spectrometer.

RESULTS

Photodissociation (PD) of the FAIBE derivatives yields abundant radical cations by loss of atomic iodine and in several cases selective dissociation of activated carbon–carbon bonds (e.g., at allylic positions) are also observed. Subsequent CID of the [M + Na – I]•+ radical cations yields radical‐directed dissociation (RDD) mass spectra that reveal extensive carbon–carbon bond dissociation without scrambling of molecular information.

CONCLUSIONS

Both PD and RDD spectra obtained from derivatized fatty acids provide a wealth of structural information including the position(s) of unsaturation, chain‐branching and hydroxylation. The structural information obtained by this approach, in particular the ability to rapidly differentiate isomeric lipids, represents a useful addition to the lipidomics tool box. Copyright © 2013 John Wiley & Sons, Ltd.
Experimental validation of a dual uplink multifrequency dispersive noise calibration scheme for Deep Space tracking
Authors: Mariotti G. , Tortora P.
Published: February 2013

We discuss the implementation and effectiveness of a dispersive noise multifrequency calibration scheme for Deep Space tracking. We show that the combination of two phase‐coherent links at X band and Ka‐band, with two separate uplink carriers, can provide an effective plasma and ionospheric noise removal, in the order of 75% of the plasma noise affecting the Ka‐band link. This algorithm, which we refer to as “Dual Uplink, Dual Downlink”, shows a modest loss in the radio link stability, if compared to the complete, state‐of‐the‐art calibration achieved by a more complex radio system, which supplements the two separate uplinks and downlinks at X band and Ka‐band with an additional “cross‐link” (X‐up/Ka‐down). The calibration accuracy of these two algorithms is thoroughly compared to define their advantages and shortcomings. Finally, Cassini's multifrequency tracking data acquired in 2002 during a General Relativity solar conjunction experiment aimed at the estimation of the parametrized post Newtonian parameter γ were reanalyzed to assess the capability of the Dual Uplink, Dual Downlink calibration algorithm to support accurate radio science experiments.
Spatial scale of land‐use impacts on riverine drinking source water quality
Authors: Hurley Tim , Mazumder Asit
Published: February 2013

Key Points

Microbial water quality most closely related to local landuse

Organic carbon concentrations only associated with entire watershed landuse

Work supports watershed scale management to protect drinking water sources
Training effects on motor–cognitive dual-task performance in older adults
Authors: Wollesen Bettina , Voelcker-Rehage Claudia
Published: February 2013

This systematic review investigated whether healthy older adults benefit from training interventions in motor–cognitive dual-task (DT) situations and which specific aspects of the intervention and/or task selection contribute to training benefits. Training effects were analysed with regard to the training programme (e.g., general ST or DT training) and task conditions (e.g., standing or walking, complexity of secondary cognitive task). Literature was searched via OVIDsp (Medline, EMBASE, PsycINFO). DT studies were included by the following criteria: (1) investigation of at least one motor task, (2) assessment of DT performance outcomes on standing or walking, (3) conduction of an intervention, and (4) investigation of older adults in an experimental–control group design or an old–young comparison. Thirteen studies met all inclusion criteria. Four types of interventions were identified: (1) general single-task (ST) motor training, (2) specific ST motor training, (3) general DT training, and (4) task-related (specific) DT training. For DT standing conditions only DT interventions improved motor performance, whereas DT walking also benefits by ST training. Most benefits on motor and cognitive performance seem to be reached by DT training interventions whereas a GST produced lowest effects. Thus, balance orientated motor and cognitive DT performance in healthy older adults can be improved by performance related exercises. Furthermore, to reach beneficial effects, it seems necessary that the training intervention includes a certain level of exercise load such as rising difficulties, appropriate intensity and duration, a certain level of task specificity, and variable task prioritization. The transfer of training effects into everyday situations needs to be further investigated.
Phase transitions in four-dimensional binary hard hypersphere mixtures
Authors: Bishop Marvin , Whitlock Paula A.
Published: February 2013

Previous Monte Carlo investigations of binary hard hyperspheres in four-dimensional mixtures are extended to higher densities where the systems may solidify. The ratios of the diameters of the hyperspheres examined were 0.4, 0.5, and 0.6. Only the 0.4 system shows a clear two phase, solid-liquid transition and the larger component solidifies into a D4 crystal state. Its pair correlation function agrees with that of a one component fluid at an appropriately scaled density. The 0.5 systems exhibit states that are a mix of D4 and A4 regions. The 0.6 systems behave similarly to a jammed state rather than solidifying into a crystal. No demixing into two distinct fluid phases was observed for any of the simulations.
Characterization of the THz radiation source at the Frascati linear accelerator
Authors: Chiadroni E. , Bellaveglia M. , Calvani P. , Castellano M. , Catani L. , Cianchi A. , Di Pirro G. , Ferrario M. , Gatti G. , Limaj O. , Lupi S. , Marchetti B. , Mostacci A. , Pace E. , Palumbo L. , Ronsivalle C. , Pompili R. , Vaccarezza C.
Published: February 2013

The linac driven coherent THz radiation source at the SPARC-LAB test facility is able to deliver broadband THz pulses with femtosecond shaping. In addition, high peak power, narrow spectral bandwidth THz radiation can be also generated, taking advantage of advanced electron beam manipulation techniques, able to generate an adjustable train of electron bunches with a sub-picosecond length and with sub-picosecond spacing. The paper reports on the manipulation, characterization, and transport of the electron beam in the bending line transporting the beam down to the THz station, where different coherent transition radiation spectra have been measured and studied with the aim to optimize the THz radiation performances.
Molecular dynamics simulation indicating cold denaturation of β-hairpins
Authors: Shao Qiang , Shi Jiye , Zhu Weiliang
Published: February 2013

The folding of a series of β-hairpin structured polypeptides, which share high sequence similarity but differ significantly in structure resistance to temperature decrease, was investigated in the present study using integrated-tempering-sampling molecular dynamics simulations on microsecond time scale. MrH3a is a single mutant (I16A) and MrH4a is a double mutant (Y3L/I16A) of the wild-type polypeptide MrH1. MrH3b and MrH4b have an additional mutation in the turn region (INGK → IDPGK) of MrH3a and MrH4a, respectively. It was observed in the present study that the cold denaturation tendency follows the order of MrH1 > MrH4a > MrH3a, while the folded structures of MrH3b and MrH4b have the enhanced stability and are not subject to cold denaturation. These observations are in good agreement with experimental results of Maynard et al. and Dyer et al. Comparative analysis of simulation results for the 5 polypeptides revealed potential mechanism of β-hairpin cold denaturation. The main determinant of cold denaturation tendency is likely the stability decrease of backbone hydrogen bonds at low temperatures, which in turn is affected by the packing manner of the hydrophobic core cluster of β-hairpin structures.
Useful lower limits to polarization contributions to intermolecular interactions using a minimal basis of localized orthogonal orbitals: Theory and analysis of the water dimer
Authors: Azar R. Julian , Horn Paul Richard , Sundstrom Eric Jon , Head-Gordon Martin
Published: February 2013

The problem of describing the energy-lowering associated with polarization of interacting molecules is considered in the overlapping regime for self-consistent field wavefunctions. The existing approach of solving for absolutely localized molecular orbital (ALMO) coefficients that are block-diagonal in the fragments is shown based on formal grounds and practical calculations to often overestimate the strength of polarization effects. A new approach using a minimal basis of polarized orthogonal local MOs (polMOs) is developed as an alternative. The polMO basis is minimal in the sense that one polarization function is provided for each unpolarized orbital that is occupied; such an approach is exact in second-order perturbation theory. Based on formal grounds and practical calculations, the polMO approach is shown to underestimate the strength of polarization effects. In contrast to the ALMO method, however, the polMO approach yields results that are very stable to improvements in the underlying AO basis expansion. Combining the ALMO and polMO approaches allows an estimate of the range of energy-lowering due to polarization. Extensive numerical calculations on the water dimer using a large range of basis sets with Hartree-Fock theory and a variety of different density functionals illustrate the key considerations. Results are also presented for the polarization-dominated Na+CH4 complex. Implications for energy decomposition analysis of intermolecular interactions are discussed.
Ultralow thermal conductivity in Si/GexSi1−x core-shell nanowires
Authors: Xie Guofeng , Li Baohua , Yang Liwen , Cao Juexian , Guo Zhixin , Tang Minghua , Zhong Jianxin
Published: February 2013

By applying non-equilibrium molecular dynamics simulation, it is demonstrated that the thermal conductivity of the reported Si/Ge core-shell nanowires (NWs) can be further reduced by shell doping. The thermal conductivity of Si/Ge0.6Si0.4 core-shell NWs is only about 66% of that of Si/Ge core-shell NWs. By analyzing the participation ratios of eigenmodes, it is revealed that the large reduction in the thermal conductivity of Si/Ge0.6Si0.4 core-shell NWs stems from the strong localization of the phonon modes from 1.0 THz to 2.0 THz and the modes from 9.0 THz to 16.0 THz due to both impurity scattering and interface scattering associated with peculiar structure of shell doped silicon NWs.
Ultrafast pump-probe spectroscopic signatures of superconducting and pseudogap phases in YBa2Cu3O7−δ films
Authors: Zhang Chunfeng , Li Wei , Gray B. , He Bin , Wang Ye , Yang Fan , Wang Xiaoyong , Chakhalian J. , Xiao Min
Published: February 2013

Femtosecond pump-probe spectroscopy is applied to identify transient optical signatures of phase transitions in nearly optimally doped YBa2Cu3O7−δ films. To elucidate the dynamics of superconducting and pseudogap phases, the slow thermal component is removed from the time-domain traces of photo-induced reflectivity in a high-flux regime with low frequency pulse rate. The rescaled data exhibit distinct signatures of the phase separation with abrupt changes at the onsets of TSC and TPG in excellent agreement with the transport data. Compared to the superconducting phase, the response of the pseudogap phase is characterized by the strongly reduced reflectivity change accompanied by a faster recovery time.
Enhancement of multisubband electron mobility in parabolic AlxGa1−xAs-GaAs double quantum well structures
Authors: Sahu Trinath , Palo Sangeeta , Panda A. K.
Published: February 2013

We analyze the low temperature multisubband electron mobility in AlxGa1−xAs–GaAs parabolic double quantum well structures in which the outer barriers are delta doped with Si. The structural parabolic potential, obtained from gradual variation of the alloy fraction x (from 0 to xp), partly compensates the triangular like potential profile near the outer interfaces inducing the electrons to move towards the centre of the wells. We study the effect of interplay of ionized impurity (II) scattering and alloy disorder (AD) scattering on the subband mobility. We show that when single subband is occupied both II- and AD-scatterings govern the mobility. However, once second subband is occupied, the mobility is influenced by II-scattering mediated by intersubband effects. It is gratifying to show that the mobility is considerably enhanced in parabolic double quantum wells (0.3 ≥ xp > 0) compared to the square double quantum well structures (xp = 0) at large well widths where double subband is occupied. By increasing the electron density (Ns), the enhancement increases further. We also show that in case of a parabolic single quantum well structure large enhancement in mobility is obtained compared to that of square single quantum well structure as long as single subband is occupied, unlike the double quantum well systems. Our results of mobility in parabolic double quantum wells can be utilized for low temperature device applications.
A sense of presence
Authors: Clark Andy
Published: February 2013

Our apparently simple and basic sense of our own location is, I argue, the fruit of an ongoing project. It is a construct formed by our implicit awareness of our current set of potentials for action, social engagement and intervention. Nonetheless, most attempts at technologically supported telepresence seem shallow and unsatisfying. In what follows, I explore the potential of richer and more varied technologies to impact our fundamental sense of location.
Bone Fracture Exacerbates Murine Ischemic Cerebral Injury
Authors: Degos Vincent , Maze Mervyn , Vacas Susana , Hirsch Jan , Guo Yi , Shen Fanxia , Jun Kristine , van Rooijen Nico , Gressens Pierre , Young William L. , Su Hua
Published: February 2013

Background:

Bone fracture increases alarmins and proinflammatory cytokines in the blood, and provokes macrophage infiltration and proinflammatory cytokine expression in the hippocampus. We recently reported that stroke is an independent risk factor after bone surgery for adverse outcome; however, the impact of bone fracture on stroke outcome remains unknown. We tested the hypothesis that bone fracture, shortly after ischemic stroke, enhances stroke-related injuries by augmenting the neuroinflammatory response.

Methods:

Tibia fracture (bone fracture) was induced in mice one day after permanent occlusion of the distal middle cerebral artery (stroke). High-mobility-group box chromosomal protein-1 (HMGB1) was tested to mimic the bone fracture effects. HMGB1 neutralizing antibody and clodrolip (macrophage depletion) were tested to attenuate the bone fracture effects. Neurobehavioral function (n = 10), infarct volume, neuronal death, and macrophages/microglia infiltration (n = 6–7) were analyzed after 3 days.

Results:

We found that mice with both stroke and bone fracture had larger infarct volumes (mean percentage of ipsilateral hemisphere ± SD: 30±7% vs.12±3%, n = 6, P < 0.001), more severe neurobehavioral dysfunction, and more macrophages/microglia in the periinfarct region than mice with stroke only. Intraperitoneal injection of HMGB1 mimicked, whereas neutralizing HMGB1 attenuated, the bone fracture effects and the macrophage/microglia infiltration. Depleting macrophages with clodrolip also attenuated the aggravating effects of bone fracture on stroke lesion and behavioral dysfunction.

Conclusions:

These novel findings suggest that bone fracture shortly after stroke enhances stroke injury via augmented inflammation through HMGB1 and macrophage/microglia infiltration. Interventions to modulate early macrophage/microglia activation could be therapeutic goals to limit the adverse consequences of bone fracture after stroke.
Pseudomonas

formosensis sp. nov., a gamma-proteobacteria isolated from food-waste compost in Taiwan
Authors: Lin Shih-Yao , Hameed Asif , Liu You-Cheng , Hsu Yi-Han , Lai Wei-An , Young Chiu-Chung
Published: February 2013

A taxonomic study was carried out on a novel aerobic bacterial strain, designated CC-CY503T, isolated from food-waste compost in Taiwan. Cells were Gram-stain-negative short rods, motile by means of a monopolar flagellum. Strain CC-CY503T was able to grow at 20–50 °C and pH 6.0–10.0 and to tolerate <6 % NaCl (w/v). Phylogenetic analysis of 16S rRNA gene sequences showed that this bacterium belonged to the genus

Pseudomonas

, with

Pseudomonas pertucinogena

ATCC 190T as the closest neighbour, sharing a sequence similarity of 97.9 %. The DNA–DNA relatedness value of strain CC-CY503T with

P. pertucinogena

ATCC 190T was 37.8±2.3 %. The phylogenetic trees reconstructed based on gyrB and rpoB gene sequences supported the classification of strain CC-CY503T as a novel member of the genus

Pseudomonas

. The predominant quinone system was ubiquinone (Q-9) and the DNA G+C content was 63.1±0.4 mol%. The major fatty acids were C12 : 0, C16 : 0, C17 : 0 cyclo, C19 : 0 cyclo ω8c and summed features 3 and 8 consisting of C16 : 1ω7c/C16 : 1ω6c and C18 : 1ω7c/C18 : 1ω6c, respectively. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and phosphatidylcholine. On the basis of its distinct phylogenetic, phenotypic and chemotaxonomic features, strain CC-CY503T ( = BCRC 80437T = JCM 18415T) is proposed to represent a novel species within the genus

Pseudomonas

, for which the name

Pseudomonas

formosensis sp. nov. is proposed.
Lysinibacillus

contaminans sp. nov., isolated from surface water
Authors: Kämpfer Peter , Martin Karin , Glaeser Stefanie P.
Published: February 2013

A Gram-positive-staining, aerobic, endospore-forming bacterium, isolated as a contamination from an enrichment of enteric bacteria from surface water, was studied using a polyphasic taxonomic approach. 16S rRNA gene sequence similarity comparisons revealed that strain FSt3AT was grouped in the genus

Lysinibacillus

, most closely related to

Lysinibacillus xylanilyticus

XDB9T (98.1 %),

Lysinibacillus parviboronicapiens

BAM-582T and

Lysinibacillus sphaericus

DSM 28T (both 98.0 %). The 16S rRNA gene sequence similarity to other species of the genus

Lysinibacillus

was <97.5 %. The allocation to the genus

Lysinibacillus

was supported by a detailed chemotaxonomic characterization revealing a cell wall containing alanine, glutamic acid, aspartic acid and the diagnostic diamino acid lysine in a molar ratio of 1.6 : 1 : 0.9 : 0.8 (peptidoglycan type A4α), the major menaquinones MK-7 and MK-6, and polar lipids consisting of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, four unknown phospholipids, one unknown aminophospholipid and one unidentified aminolipid. The major fatty acids were iso- and anteiso-branched fatty acids. DNA–DNA hybridizations with the type strains of the most closely related species,

L. parviboronicapiens

DSM 25242T,

L. xylanilyticus

DSM 23493T and

L. sphaericus

DSM 28T, in addition to the results of physiological and biochemical tests, allowed genotypic and phenotypic differentiation of strain FSt3AT from these related species. Thus, FSt3AT represents a novel species of the genus

Lysinibacillus

, for which the name

Lysinibacillus

contaminans sp. nov. is proposed, with FSt3AT ( = CCM 8383T = DSM 25560T = CIP 110362T) as the type strain.
Emerging markers in cardiovascular disease: Where does angiotensin‐converting enzyme 2 fit in?
Authors: Patel Sheila K , Velkoska Elena , Burrell Louise M
Published: February 2013

The renin–angiotensin system plays a major role in the pathophysiology of cardiovascular disease (CVD). The enzyme angiotensin‐converting enzyme (ACE) converts angiotensin (Ang) I into the vasoconstrictor AngII and was thought, until recently, to be the main effector of the system.

The enzyme ACE2, discovered in 2000, can counterbalance the effects of ACE through degradation of AngII and generation of Ang‐(1–7). Angiotensin‐converting enzyme 2 is abundantly expressed in the heart and localized to the endothelial cells of coronary vessels and smooth muscle cells. Its catalytically active ectodomain undergoes shedding, resulting in ACE2 in the circulation.

There are 10 studies to date that have measured circulating ACE2 activity in humans, including in healthy subjects and those with heart failure, Type 1 diabetes, implantable cardioverter/defibrillator, elderly subjects undergoing emergency orthopaedic surgery and kidney transplant patients. The results suggest that circulating ACE2 activity may be a marker of CVD, with low levels in healthy individuals and increased levels in those with cardiovascular risk factors or disease. Whether increased plasma ACE2 activity reflects increased synthesis from tissue ACE2 mRNA or increased shedding of tissue ACE2 remains to be determined.

Angiotensin‐converting enzyme 2 is located on the X‐chromosome and circulating ACE2 levels are higher in men than in women.

Large clinical studies in CVD are needed to more precisely clarify the role of ACE2 as a biomarker of CVD, determine the prognostic significance of circulating ACE2 activity and assess whether the measurement of ACE2 will improve CVD risk prediction.
Vitamin D supplementation reduces airway hyperresponsiveness and allergic airway inflammation in a murine model
Authors: Agrawal T. , Gupta G. K. , Agrawal D. K.
Published: February 2013

Background

Asthma is a chronic disease associated with airway hyperresponsiveness (AHR), airway obstruction and airway remodelling. NF‐κB is a transcriptional factor that regulates and co‐ordinates the expression of various inflammatory genes. The NF‐κB subunits, p50 and Rel‐A, are translocated to the nucleus by importin α3 and importin α4. There is growing evidence that vitamin D is a potent immunomodulator. However, the evidence for beneficial or adverse effects of vitamin D in asthma is still unclear.

Objective

In this study, we examined the effect of vitamin D status on AHR, airway inflammation and cytokines in the bronchoalveolar lavage fluid (BALF) in a murine model of allergic asthma.

Methods

Female BALB/c mice were fed with special vitamin D‐deficient or vitamin D‐sufficient (2000 IU/kg) or vitamin D‐supplemented (10 000 IU/kg) diet for 13 weeks. Mice were sensitized and challenged with ovalbumin (OVA). The effect of vitamin D on lung histology, AHR, T regulatory cells (Tregs) and BALF cytokines was examined. The expression of importin‐α3 and Rel‐A in the lung of OVA‐sensitized mice was analysed using immunofluorescence.

Results

Vitamin D deficiency was associated with higher AHR in OVA‐sensitized and challenged mice than those in vitamin D‐sufficient mice. This was accompanied with marked signs of airway remodelling, high BALF eosinophilia, increased BALF pro‐inflammatory cytokines, reduced BALF IL‐10 levels, reduced blood Tregs, increased expression of importin‐α3 and Rel‐A in the lung tissue. Vitamin D supplementation attenuated the pro‐inflammatory effects, but did not completely reverse the features of allergic airway inflammation.

Conclusion and Clinical Relevance

Vitamin D could be beneficial as an adjunct therapy in the treatment of allergic asthma.
Speed isn't everything: complex processing speed measures mask individual differences and developmental changes in executive control
Authors: Cepeda Nicholas J. , Blackwell Katharine A. , Munakata Yuko
Published: February 2013

The rate at which people process information appears to influence many aspects of cognition across the lifespan. However, many commonly accepted measures of ‘processing speed’ may require goal maintenance, manipulation of information in working memory, and decision‐making, blurring the distinction between processing speed and executive control and resulting in overestimation of processing speed contributions to cognition. This concern may apply particularly to studies of developmental change, as even seemingly simple processing speed measures may require executive processes to keep children and older adults on task. We report two new studies and a re‐analysis of a published study, testing predictions about how different processing speed measures influence conclusions about executive control across the lifespan. We find that the choice of processing speed measure affects the relationship observed between processing speed and executive control, in a manner that changes with age, and that choice of processing speed measure affects conclusions about development and the relationship among executive control measures. Implications for understanding processing speed, executive control, and their development are discussed.
An exploratory study of contrast agents for soft tissue visualization by means of high resolution X‐ray computed tomography imaging
Authors: PAUWELS E. , VAN LOO D. , CORNILLIE P. , BRABANT L. , VAN HOOREBEKE L.
Published: February 2013

High resolution X‐ray computed tomography (CT), or microCT, is a promising and already widely used technique in various scientific fields. Also for histological purposes it has great potential. Although microCT has proven to be a valuable technique for the imaging of bone structures, the visualization of soft tissue structures is still an important challenge due to their low inherent X‐ray contrast. One way to achieve contrast enhancement is to make use of contrast agents. However, contrary to light and electron microscopy, knowledge about contrast agents and staining procedures is limited for X‐ray CT. The purpose of this paper is to identify useful X‐ray contrast agents for soft tissue visualization, which can be applied in a simple way and are also suited for samples larger than (1 cm)3. And 28 chemical substances have been investigated. All chemicals were applied in the form of concentrated aqueous solutions in which the samples were immersed. First, strips of green Bacon were stained to evaluate contrast enhancement between muscle and adipose tissue. Furthermore it was also tested whether the contrast agents remained fixed in the tissue after staining by re‐immersing them in water. Based on the results, 12 contrast agents were selected for further testing on postmortem mice hind legs, containing a variety of different tissues, including muscle, fat, bone, cartilage and tendons. It was evaluated whether the contrast agents allowed a clearer distinction between the different soft tissue structures present. Finally also penetration depth was measured. And 26 chemicals resulted in contrast enhancement between muscle and adipose tissue in the Bacon strips. Mercury(II)chloride (HgCl2), phosphotungstic acid (PTA), phosphomolybdic acid (PMA) and ammonium orthomolybdate ((NH4)2MoO4) remained fixed after re‐immersion in water. The penetration tests showed that potassium iodide (KI) and sodium tungstate can be most efficiently used for large samples of the order of several tens of cm3. PMA, PTA, HgCl2and also to a lesser extent Na2WO4and (NH4)2MoO4allowed a clearer distinction between the different soft tissue structures present.