bluuebunny/crossref_metadata_2025 huggingface dataset:
Signatures of correlated excitonic dynamics in two-dimensional spectroscopy of the Fenna-Matthew-Olson photosynthetic complex
Authors: Caram Justin R. , Lewis Nicholas H. C. , Fidler Andrew F. , Engel Gregory S.
Published: March 2012

Long-lived excitonic coherence in photosynthetic proteins has become an exciting area of research because it may provide design principles for enhancing the efficiency of energy transfer in a broad range of materials. In this publication, we provide new evidence that long-lived excitonic coherence in the Fenna-Mathew-Olson pigment-protein (FMO) complex is consistent with the assumption of cross correlation in the site basis, indicating that each site shares bath fluctuations. We analyze the structure and character of the beating crosspeak between the two lowest energy excitons in two-dimensional (2D) electronic spectra of the FMO Complex. To isolate this dynamic signature, we use the two-dimensional linear prediction Z-transform as a platform for filtering coherent beating signatures within 2D spectra. By separating signals into components in frequency and decay rate representations, we are able to improve resolution and isolate specific coherences. This strategy permits analysis of the shape, position, character, and phase of these features. Simulations of the crosspeak between excitons 1 and 2 in FMO under different regimes of cross correlation verify that statistically independent site fluctuations do not account for the elongation and persistence of the dynamic crosspeak. To reproduce the experimental results, we invoke near complete correlation in the fluctuations experienced by the sites associated with excitons 1 and 2. This model contradicts ab initio quantum mechanic/molecular mechanics simulations that observe no correlation between the energies of individual sites. This contradiction suggests that a new physical model for long-lived coherence may be necessary. The data presented here details experimental results that must be reproduced for a physical model of quantum coherence in photosynthetic energy transfer.
Fragment momentum distributions obtained from coupled electron-nuclear dynamics
Authors: Hader Kilian , Engel Volker
Published: March 2012

We theoretically investigate fragmentation processes induced by femtosecond laser pulses within a model which incorporates electronic and nuclear motion. Single-pulse excitation leads to diffraction patterns in the electron momentum distribution which depend on the nature of the electronic state and also on the nuclear charge distribution. Additional structures appear in the nuclear momentum distribution if two time-delayed pulses produce fragments in the same dissociation channel. It is shown that these functions are modified by the electronic degree-of-freedom. A simultaneous excitation of two different electronic states results in further interferences which are related to electronic wave-packet dynamics on the attosecond time-scale.
Holographic optical bottle beams
Authors: Alpmann Christina , Esseling Michael , Rose Patrick , Denz Cornelia
Published: March 2012

We present a convolution approach for the generation of optical bottle beams that combines established techniques of holographic optical trapping with hollow intensity distributions in order to manipulate absorbing particles. The versatility of our method is demonstrated by the simultaneous stable trapping of multiple particles at defined positions. Furthermore, the presented phase shaping technique allows for the dynamic manipulation of absorbing particles along arbitrary paths.
Generating large-area uniform microwave field for plasma excitation
Authors: Chang T. H. , Chen N. C. , Chao H. W. , Lin J. C. , Huang C. C. , Chen C. C.
Published: March 2012

This study proposes a distributed input system to generate large-area uniform microwave field for the applications of plasma excitation or material processing. A microwave source is divided into four equal-amplitude and equal-phase waves through cascaded H-plane and E-plane power dividers. The wave in rectangular TE10 mode is subsequently converted into cylindrical TE11 mode and then propagates through a slightly deformed waveguide to form a circularly polarized wave. The four circularly polarized waves with a 2 × 2 input array are led into a reaction chamber to excite plasma or an applicator to process materials. An experiment was conducted, which verified the simulated results. The idea of generating uniform microwave field can be scaled to a much larger area if an n × n input array is used
Unified formalism for higher order non-autonomous dynamical systems
Authors: Prieto-Martínez Pedro Daniel , Román-Roy Narciso
Published: March 2012

This work is devoted to giving a geometric framework for describing higher order non-autonomous mechanical systems. The starting point is to extend the Lagrangian-Hamiltonian unified formalism of Skinner and Rusk for these kinds of systems, generalizing previous developments for higher order autonomous mechanical systems and first-order non-autonomous mechanical systems. Then, we use this unified formulation to derive the standard Lagrangian and Hamiltonian formalisms, including the Legendre-Ostrogradsky map and the Euler-Lagrange and the Hamilton equations, both for regular and singular systems. As applications of our model, two examples of regular and singular physical systems are studied.
Dependence of dark spot growth on cathode/organic interfacial adhesion in organic light emitting devices
Authors: Phatak R. , Tsui T. Y. , Aziz H.
Published: March 2012

The growth of dark spots in organic light emitting devices (OLEDs) with cathodes deposited at 65°C instead of the conventional room temperature deposition, or which contain a metal-organic-mixed layer at the cathode contact, is investigated. The results reveal a strong correlation between the growth rate of dark spots and adhesion at the cathode-organic interface, where stronger adhesion results in a slower growth of dark spots. The findings shed light on the beneficial effect of increasing interfacial adhesion on improving the ambient stability of OLEDs. Measures for increasing cathode-organic adhesion can be expected to be particularly beneficial for flexible OLEDs where device protection from the ambient is more challenging.
Jets in quiescent bubbles caused by a nearby oscillating bubble
Authors: Pain Agnès , Hui Terence Goh Bing , Klaseboer Evert , Ohl Siew-Wan , Cheong Khoo Boo
Published: March 2012

An oscillating bubble near another (stationary) bubble can give rise to interesting interactions. Such a nonequilibrium (oscillating) bubble can create a jet in a smaller nearby (initially stationary) bubble as demonstrated in this study both experimentally and numerically. In the experimental study, a spark-generated bubble (through a short circuit with two electrodes) was generated near a stationary smaller bubble. In order to keep the millimeter-sized bubble stationary, it was trapped in a droplet of silicone oil attached to one of the electrodes. The jet in the initially stationary bubble can reach velocities up to 250 m/s, but the velocity becomes lower for bubbles that are larger or situated further away. The current article also describes some experiments with the appearance of a crown-like secondary jet on the free surface (regarded as a large stationary bubble) relatively long after the bubble has collapsed. Some other interesting interactions of a spark-generated bubble with more than one stationary bubble are presented.
Bulk-like dielectric properties from metallo-organic solution–deposited SrTiO3 films on Pt-coated Si substrates
Authors: Weiss C. V. , Zhang J. , Spies M. , Abdallah L. S. , Zollner S. , Cole M. W. , Alpay S. P.
Published: March 2012

SrTiO3 (STO) thin films were grown onto Pt/Ti/TiO2/SiO2/Si and bare Si substrates via metallo-organic solution deposition (MOSD). X ray diffraction, scanning electron microscopy, atomic force microscopy, spectroscopic ellipsometry (SE), and dielectric/insulating measurements were utilized to characterize the STO thin films. By optimizing the solution molarity, it is shown that it is possible to obtain low-frequency dielectric properties in STO thin films on Si substrates that approach those of bulk STO: a dielectric permittivity of 325 at 100 kHz with a tunability of ∼28% at ∼650 kV/cm, a low loss (<2%), and a leakage current density of 1.0 × 10−6 A/cm2 at 100 kV/cm. The bulk-like dielectric response of these films is attributed to the elimination of the relatively large in-plane tensile thermal stresses, which arise due to the thermal expansion mismatch between the STO film and the Si substrate. These tensile thermal stresses may be relaxed or completely eliminated through modification of the post-coalescence compressive growth stresses by precursor solution optimization. The SE data indicates that the STO thin films have a refractive index of ∼2.04 at 633 nm wavelength, which is lower than that of bulk STO. The dielectric, physical, and optical characterization results above the bandgap are consistent, but below the bandgap, the optical-frequency results demonstrate a ∼25% reduced dielectric response as compared to the bulk, which may be due to the different polarization mechanisms at work at high frequencies. These findings demonstrate that high-quality, electronic-grade, thin film STO films can be grown on Si substrates via the affordable, simple, and industry-standard MOSD technique by carefully adjusting the deposition parameters.
Modeling of switching delay in gas-insulated trigatron spark gaps
Authors: Li Lee , Li Cai , Xiangdong Qi , Fuchang Lin , Yuan Pan
Published: March 2012

Based on the gas discharge theory involving distorted E-field enhancement, a physical model is proposed to estimate the switching delay for gas-insulated trigatron spark gaps with a trigger pin inside the main electrode. Two discovered breakdown modes, i.e., fast-breakdown mode (FBM) and slow-breakdown mode (SBM), can be unified in this model. Raether criterion can distinguish these two modes. If the main E-field and enhanced E-field near the trigger pin tip are great enough, FBM forms easily. Otherwise, if streamer development needs to rely on the second ionization process and relevant distorted E-field enhancement, the breakdown of the main gap would turn into SBM. The enhanced E-field near the trigger pin tip may affect the threshold main E-field of FBM. The distorted E-field enhancement may affect the switching delay length of SBM.
Engineering nonlinearity into memristors for passive crossbar applications
Authors: Joshua Yang J. , Zhang M.-X. , Pickett Matthew D. , Miao Feng , Paul Strachan John , Li Wen-Di , Yi Wei , Ohlberg Douglas A. A. , Joon Choi Byung , Wu Wei , Nickel Janice H. , Medeiros-Ribeiro Gilberto , Stanley Williams R.
Published: March 2012

Although TaOx memristors have demonstrated encouraging write/erase endurance and nanosecond switching speeds, the linear current-voltage (I-V) characteristic in the low resistance state limits their applications in large passive crossbar arrays. We demonstrate here that a TiO2-x/TaOx oxide heterostructure incorporated into a 50 nm× 50 nm memristor displays a very large nonlinearity such that I(V/2) ≈ I(V)/100 for V ≈ 1 volt, which is caused by current-controlled negative differential resistance in the device.
Green luminescence in silica glass: A possible indicator of subsurface fracture
Authors: Fournier Jessica , Neauport Jerome , Grua Pierre , Fargin Evelyne , Jubera Véronique , Talaga David , Jouannigot Stéphane
Published: March 2012

We investigate the nature of defects triggering laser damage in fused silica in subsurface fractures in nanosecond near ultraviolet regime. Mechanical, laser induced surface flaws as well as pristine silica surface were characterized by optical microscopy and luminescence confocal microscopy before and after acid etching. In all cases, photoluminescence decreases with etching time assessing the existence of defects close to the surface. Spectral analysis of the evolution of these signals during etching allows new interpretations of the nature of precursors inducing damage. Green luminescence around 2.25 eV is seen as a potential subsurface fracture indicator leading to laser damage.
Elimination of higher-order diffraction using zigzag transmission grating in soft x-ray region
Authors: Zang H. P. , Wang C. K. , Gao Y. L. , Zhou W. M. , Kuang L. Y. , Wei L. , Fan W. , Zhang W. H. , Zhao Z. Q. , Cao L. F. , Gu Y. Q. , Zhang B. H. , Jiang G. , Zhu X. L. , Xie C. Q. , Zhao Y. D. , Cui M. Q.
Published: March 2012

We present a realization of the sinusoidal transmission function using a series of zigzag-profiled strips where the transmission takes on the binary values 0 and 1 in a two-dimensional distribution. A zigzag transmission grating of 1000 line/mm has been fabricated and demonstrated on the soft x-ray beam of synchrotron radiation. The axial single-order diffraction indicates that the zigzag transmission grating is adequate for spectroscopic application.
Optical properties and electronic structure of multiferroic hexagonal orthoferrites RFeO3 (R = Ho, Er, Lu)
Authors: Pavlov V. V. , Akbashev A. R. , Kalashnikova A. M. , Rusakov V. A. , Kaul A. R. , Bayer M. , Pisarev R. V.
Published: March 2012

We report on optical studies of the thin films of multiferroic hexagonal (P.G. 6mm) rare-earth orthoferrites RFeO3 (R = Ho, Er, Lu) grown epitaxially on a (111)-surface of ZrO2(Y2O3) substrate. The optical absorption study in the range of 0.6–5.6 eV shows that the films are transparent below 1.9 eV; above this energy four broad intense absorption bands are distinguished. The absorption spectra are analyzed taking into account the unusual fivefold coordination of the Fe3+ ion. Temperature dependence of the optical absorption at 4.9 eV shows anomaly at 124 K, which we attribute to magnetic ordering of iron sublattices.
Switchable liquid crystal grating with sub millisecond response
Authors: Fan F. , Srivastava A. K. , Chigrinov V. G. , Kwok H. S.
Published: March 2012

In present article, we disclose a fast switchable grating based on nematic liquid crystals. A fine striped electrode has been exploited to generate the grating profile and a driving scheme to drive the grating cell has also been proposed, which enable us to drive the cell up to very high frequency (∼2 kHz) with evident saturated optical states. The response time for the first order diffracted beam, at the electric field of 10 V/μm, is less than 100 μs and optical contrast is higher than 400:1. Thus, the proposed LC grating could find application in several advance electro-optical devices.
Charge depletion in organic heterojunction
Authors: Ng T. W. , Lo M. F. , Lee S. T. , Lee C. S.
Published: March 2012

Until now two types of organic-organic heterojunction (OHJ) have been observed in P-N junctions formed between undoped-organic semiconductors. Charge-transfers across OHJs are either negligible or showing electron transfer from P-type to N-type materials, leading to charges accumulation near the interface. Here, we observed that junction of 4,4′,4′′-tris(2-methylphenyl-phenylamino)triphenylamine (m-MTDATA)/bathocuproine (BCP) show the third-behavior. Electrons in BCP (N-type) transfer to m-MTDATA (P-type), leading to depletion of mobile majority carriers near the junction. While “depletion junctions” are typical in inorganic semiconductors, there are no reports in undoped-OHJ. Formation mechanism of depletion OHJs and fundamental differences between inorganic and organic HJs are discussed.
Occupancy and Detection of Larval Pacific Lampreys and Lampetra spp. in a Large River: the Lower Willamette River
Authors: Jolley Jeffrey C. , Silver Gregory S. , Whitesel Timothy A.
Published: March 2012

Pacific lampreys Entosphenus tridentatus (formerly Lampetra tridentata) are declining in the Columbia River basin, and the use of large, main‐stem river habitats by larvae of this species is unknown. We used a deepwater electrofisher to explore occupancy, detection, and habitat use of larval Pacific lampreys and larval Lampetra spp. in the lower Willamette River, Oregon. We used a generalized random tessellation stratified approach to select sampling quadrats (30 × 30 m) in a random, spatially balanced order. Pacific lampreys, Lampetra spp., and unidentified lampreys were found in the Willamette River; larvae were detected in all areas except the Multnomah Channel. We calculated reach‐ and quadrat‐specific detection probabilities and the amount of sampling effort required for 80% confidence that larval lampreys were in fact absent when they were not detected. Lampreys were detected in a variety of areas (although relatively low numbers were collected), including shallow, nearshore areas; midchannel areas (depth up to 16 m); and anthropogenically affected areas. Detection probabilities (i.e., in occupied areas) were 0.07 (reach) and 0.23 (quadrat). The sampling effort required for 80% confidence that lampreys were absent when undetected was 20 quadrats (in the lower Willamette River reach) and 6 subquadrats (within a quadrat). Differences in lamprey detection by depth were not observed. A variety of sizes was collected (20–144 mm total length), indicating the likely occurrence of multiple ages of larvae. Our study identifies how the occurrence of larval Pacific lampreys can be quantified with statistical rigor in a large river (i.e., larger than fourth order [1:100,000 scale]). The effect of channel management activities on larval lampreys should be considered in efforts to conserve these important species.
Investigation of Fishing and Climate Effects on the Community Size Spectra of Eastern Bering Sea Fish
Authors: Boldt Jennifer L. , Bartkiw Shannon C. , Livingston Pat A. , Hoff Gerald R. , Walters Gary E.
Published: March 2012

The eastern Bering Sea (EBS) is a highly productive subarctic marine ecosystem that is exposed to considerable climate variability and is noted for conservative management of its fishery resources. The community size spectrum (CSS; relationship between animal abundance and size) of fish captured in EBS shelf bottom trawl surveys was examined for evidence of change over time and fishing and climate effects. The slope (indicative of fish size) and height (indicative of ecosystem productivity, or essentially fish abundance) of the CSS can change due to changes in fishing intensity and climate variability. Linear trends were not observed in EBS groundfish size or abundance during 1982–2006. The abundance of large‐sized fish increased in 2001–2006 relative to 1982–2000. Observed changes in CSS height partially corroborated evidence for decreased productivity of the main fishery target species since the late 1990s, which may have been due to changes in relative species composition. In addition, abundance and size composition of nontarget fish decreased during 1982–2006, possibly related to changes in water temperature. In contrast, however, the size and productivity of fish that were primarily bycatch species increased during 1982–2006. Unlike in other ecosystems, changes in CSS slopes and heights for the EBS were not related to exploitation rates. Changes in the abundance of fish in areas that were normally occupied by cold bottom water (northwest inner and middle shelf) may have been related to the effects of temperature on fish distribution.
Working Memory Capacity and Visual Attention: Top-Down and Bottom-Up Guidance
Authors: Shipstead Zach , Harrison Tyler L. , Engle Randall W.
Published: March 2012

Previous studies have indicated that working memory capacity (WMC) is related to visual attention when selection of critical information must be made in the face of distraction. The present study examines whether WMC-related differences in flanker task performance might be decreased by displays that are designed to support bottom-up guidance of attention. Participants were required to respond to a centrally located target while ignoring a peripheral flanker. In one condition, bottom-up support was provided by embedding the target in a row of zeros. In another condition, the zeros were removed, thus emphasizing the role of top-down attention in selecting spatially defined information. It was found that the inclusion of zeros led to the elimination of WMC-related flanker effects. We conclude that bottom-up attentional guidance can attenuate the role of WMC in selective attention.
Non-canonical alternatives: What a macrophage is 4
Authors: Karp Christopher L. , Murray Peter J.
Published: March 2012

Macrophages play pleiotropic, niche-specific roles in all tissues and organs. As immune sentinels, tissue macrophages regulate immune activation and inflammation; in turn, their function is modulated by inflammatory mediators deriving from such activation. Recent papers have established unanticipated roles for interleukin 4 and the alternative activation of tissue macrophages in the organismal response to diverse environmental stressors.
Multiphysics modelling and simulation of dry laser cleaning of micro-slots with particle contaminants
Authors: Yue Liyang , Wang Zengbo , Li Lin
Published: March 2012

Light could interact differently with thin-film contaminants and particle contaminates because of their different surface morphologies. In the case of dry laser cleaning of small transparent particles, it is well known that particles could function like mini-lenses, causing a localized near-field hot spot effect on the cleaning process. This paper looks into a special, yet important, phenomenon of dry laser cleaning of particles trapped in micro-sized slots. The effects of slot size, particle size and particle aggregate states in the cleaning process have been theoretically investigated, based on a coupled electromagnetic-thermal-mechanical multiphysics modelling and simulation approach. The study is important for the development and optimization of laser cleaning processes for contamination removal from cracks and slots.
Induced Systemic Resistance in Arabidopsis thaliana Against Pseudomonas syringae pv. tomato by 2,4-Diacetylphloroglucinol-Producing Pseudomonas fluorescens
Authors: Weller David M. , Mavrodi Dmitri V. , van Pelt Johan A. , Pieterse Corné M. J. , van Loon Leendert C. , Bakker Peter A. H. M.
Published: March 2012

Pseudomonas fluorescens strains that produce the polyketide antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG) are among the most effective rhizobacteria that suppress root and crown rots, wilts, and damping-off diseases of a variety of crops, and they play a key role in the natural suppressiveness of some soils to certain soilborne pathogens. Root colonization by 2,4-DAPG-producing P. fluorescens strains Pf-5 (genotype A), Q2-87 (genotype B), Q8r1-96 (genotype D), and HT5-1 (genotype N) produced induced systemic resistance (ISR) in Arabidopsis thaliana accession Col-0 against bacterial speck caused by P. syringae pv. tomato. The ISR-eliciting activity of the four bacterial genotypes was similar, and all genotypes were equivalent in activity to the well-characterized strain P. fluorescens WCS417r. The 2,4-DAPG biosynthetic locus consists of the genes phlHGF and phlACBDE. phlD or phlBC mutants of Q2-87 (2,4-DAPG minus) were significantly reduced in ISR activity, and genetic complementation of the mutants restored ISR activity back to wild-type levels. A phlF regulatory mutant (overproducer of 2,4-DAPG) had ISR activity equivalent to the wild-type Q2-87. Introduction of DAPG into soil at concentrations of 10 to 250 μM 4 days before challenge inoculation induced resistance equivalent to or better than the bacteria. Strain Q2-87 induced resistance on transgenic NahG plants but not on npr1-1, jar1, and etr1 Arabidopsis mutants. These results indicate that the antibiotic 2,4-DAPG is a major determinant of ISR in 2,4-DAPG-producing P. fluorescens, that the genotype of the strain does not affect its ISR activity, and that the activity induced by these bacteria operates through the ethylene- and jasmonic acid-dependent signal transduction pathway.
Bacterial secretion comes of age
Authors: Waksman Gabriel
Published: March 2012

Bacterial secretion systems play essential roles in pathogenesis and also in maintaining lines of communication between bacterial cells in the bacterial microflora or between commensal bacteria and their host. Recent breakthroughs in the field have yielded some novel insights into the mechanisms by which these systems operate. This issue of
Philosophical Transactions B
seeks to provide a detailed survey of the field, with an emphasis on mechanisms and how their unravelling might provide a new future for antibiotics research.
The bacterial Sec-translocase: structure and mechanism
Authors: Lycklama a Nijeholt Jelger A. , Driessen Arnold J. M.
Published: March 2012

Most bacterial secretory proteins pass across the cytoplasmic membrane via the translocase, which consists of a protein-conducting channel SecYEG and an ATP-dependent motor protein SecA. The ancillary SecDF membrane protein complex promotes the final stages of translocation. Recent years have seen a major advance in our understanding of the structural and biochemical basis of protein translocation, and this has led to a detailed model of the translocation mechanism.
Structure and mechanism of the tripartite CusCBA heavy-metal efflux complex
Authors: Long Feng , Su Chih-Chia , Lei Hsiang-Ting , Bolla Jani Reddy , Do Sylvia V. , Yu Edward W.
Published: March 2012

Gram-negative bacteria frequently expel toxic chemicals through tripartite efflux pumps that span both the inner and outer membranes. The three parts are the inner membrane, substrate-binding transporter (or pump); a periplasmic membrane fusion protein (MFP, or adaptor); and an outer membrane-anchored channel. The fusion protein connects the transporter to the channel within the periplasmic space. One such efflux system CusCBA is responsible for extruding biocidal Cu(I) and Ag(I) ions. We previously described the crystal structures of both the inner membrane transporter CusA and the MFP CusB of
Escherichia coli
. We also determined the co-crystal structure of the CusBA adaptor–transporter efflux complex, showing that the transporter CusA, which is present as a trimer, interacts with six CusB protomers and that the periplasmic domain of CusA is involved in these interactions. Here, we summarize the structural information of these efflux proteins, and present the accumulated evidence that this efflux system uses methionine residues to bind and export Cu(I) and Ag(I). Genetic and structural analyses suggest that the CusA pump is capable of picking up the metal ions from both the periplasm and the cytoplasm. We propose a stepwise shuttle mechanism for this pump to export metal ions from the cell.
The blueprint of the type-3 injectisome
Authors: Kosarewicz Agata , Königsmaier Lisa , Marlovits Thomas C.
Published: March 2012

Type-3 secretion systems are sophisticated syringe-like nanomachines present in many animal and plant Gram-negative pathogens. They are capable of translocating an arsenal of specific bacterial toxins (effector proteins) from the prokaryotic cytoplasm across the three biological membranes directly into the eukaryotic cytosol, some of which modulate host cell mechanisms for the benefit of the pathogen. They populate a particular biological niche, which is maintained by specific, pathogen-dependent effectors. In contrast, the needle complex, which is the central component of this specialized protein delivery machine, is structurally well-conserved. It is a large supramolecular cylindrical structure composed of multiple copies of a relatively small subset of proteins, is embedded in the bacterial membranes and protrudes from the pathogen's surface with a needle filament. A central channel traverses the entire needle complex, and serves as a hollow conduit for proteins destined to travel this secretion pathway. In the past few years, there has been a tremendous increase in an understanding on both the structural and the mechanistic level. This review will thus focus on new insights of this remarkable molecular machine.
Holotranscobalamin Is a Useful Marker of Vitamin B12 Deficiency in Alcoholics
Authors: Fragasso Alberto , Mannarella Clara , Ciancio Angela , Scarciolla Oronzo , Nuzzolese Nicoletta , Clemente Rocco , Vitullo Eustachio , Sacco Andrea
Published: March 2012

Background. Measurement of serum cobalamin (Cbl) levels is the standard investigation for assessing vitamin B12 deficiency. Falsely increased values of Cbl can be caused by alcoholic liver disease. Measurement of total vitamin B12 serum levels might be misleading in alcoholics, because a tissue metabolic deficiency is possible even with normal serum Cbl levels. Holotranscobalamin (HoloTC), the Cbl metabolically active fraction, is considered as a better index of vitamin B12 deficiency.Methods. For assessing vitamin B12 status, we evaluated 22 adult alcoholic male patients by measuring in parallel serum Cbl, serum folate and red blood cell folate levels, HoloTC levels by the AxSYM assay.Results. HoloTC values were reduced in 3 alcoholics with borderline-low Cbl values. Significant positive correlations were found between serum Cbl and HoloTC levels, serum Cbl and gamma-glutamyl transpeptidase (GGT).Conclusion. HoloTC measurement is a useful option for assessing vitamin B12 status in alcoholics, particularly in the subjects with borderline Cbl values and may be considered an early marker of vitamin B12 deficiency.
An Efficient Protocol for the Synthesis of Quinoxaline Derivatives at Room Temperature Using Recyclable Alumina-Supported Heteropolyoxometalates
Authors: Ruiz Diego M. , Autino Juan C. , Quaranta Nancy , Vázquez Patricia G. , Romanelli Gustavo P.
Published: March 2012

We report a suitable quinoxaline synthesis using molybdophosphovanadates supported on commercial alumina cylinders as catalysts. These catalysts were prepared by incipient wetness impregnation. The catalytic test was performed under different reaction conditions in order to know the performance of the synthesized catalysts. The method shows high yields of quinoxaline derivatives under heterogeneous conditions. Quinoxaline formation was obtained using benzyl,o-phenylenediamine, and toluene as reaction solvent at room temperature. The CuH2PMo11VO40supported on alumina showed higher activity in the tested reaction. Finally, various quinoxalines were prepared under mild conditions and with excellent yields.
Increasing the Stimulation Dose of rFSH in Unexpected Poor Responders Is Not Associated with Better IVF Outcome
Authors: Tutuncu Levent , Dundar Ozgur
Published: March 2012

The aim of this retrospective study is to determine whether increasing the stimulation dose of rFSH in unexpected poor responders is associated with better in vitro fertilization (IVF) outcome or not. A total of forty eligible women who fulfilled our definition of poor responders and who did not achieve an ongoing pregnancy in the first cycle and returned for a second higher rFSH dose IVF cycle with a long-agonist protocol were included to the study. The first low-dose cycles and the second high-dose cycles were compared to each other. Main outcome measures of the study were duration of stimulation, number of follicles, number of oocytes retrieved, number of embryos, and E2 level on day of hCG injection. There were no significant differences in duration of stimulation, number of follicles, number of oocytes retrieved, number of embryos, and E2 level on day of hCG injection between the first low- and second high-dose cycles. Daily dose and total dose of rFSH were significantly higher in the second high-dose cycles. Increasing the dose of rFSH in a second stimulation cycle after first unsuccessful treatment cycle will add only to the cost and discomfort of the treatment and might adversely affect pregnancy rates.
Two New Reference Materials Based on Tobacco Leaves: Certification for over a Dozen of Toxic and Essential Elements
Authors: Samczyński Zbigniew , Dybczyński Rajmund S. , Polkowska-Motrenko Halina , Chajduk Ewelina , Pyszynska Marta , Danko Bożena , Czerska Elżbieta , Kulisa Krzysztof , Doner Katarzyna , Kalbarczyk Paweł
Published: March 2012

The preparation, certification, and characterization of two new biological certified reference materials for inorganic trace analysis have been presented. They are based on two different varieties of tobacco leaves, namely, Oriental Basma Tobacco Leaves (INCT-OBTL-5), grown in Greece, and Polish Virginia Tobacco Leaves (INCT-PVTL-6), grown in Poland. Certification of the materials was based on the statistical evaluation of results obtained in a worldwide interlaboratory comparison, in which 87 laboratories from 18 countries participated, providing 2568 laboratory averages on nearly 80 elements. It was possible to establish the certified values of concentration for many elements in the new materials, that is, 37 in INCT-OBTL-5 and 36 in INCT-PVTL-6, including several toxic ones like As, Cd, Hg, Pb, and so forth. The share and the role of instrumental analytical techniques used in the process of certification of the new CRMs are discussed.
Endoparasite Infections in Pet and Zoo Birds in Italy
Authors: Papini Roberto , Girivetto Martine , Marangi Marianna , Mancianti Francesca , Giangaspero Annunziata
Published: March 2012

Faecal samples were individually collected from pet (n=63) and zoo (n=83) birds representing 14 orders and 63 species. All the samples were examined by faecal flotation technique. In a subgroup of samples (n=75), molecular assays were also used to detectCryptosporidiumoocysts andGiardia duodenaliscysts. Overall, 35.6% of the birds harboured parasites (42.2% of zoo birds and 27% of pet birds), including Strongyles-Capillarids (8.9%),Ascaridia(6.8%), Strongyles (5.5%),G. duodenalisAssemblage A (5.3%), Coccidia (4.1%),Cryptosporidium(4%),Porrocaecum(2.7%),Porrocaecum-Capillarids (2%), andSyngamus-Capillarids (0.7%). The zoonoticG. duodenalisAssemblage A andCryptosporidiumwere exclusively found in Psittaciformes, with prevalences of 10.3% and 7.7% within this bird group. Zoo birds were more likely to harbor mixed infections (OR = 14.81) and symptomatic birds to be parasitized (OR = 4.72). Clinicians should be aware of the public health implications posed by zoonoticG. duodenalisAssemblages andCryptosporidiumspecies in captive birds.
Socioeconomic Differences in Tobacco Smoking in Italy: Is There an Interaction between Variables?
Authors: Semyonov Leda , Iarocci Gianluca , Boccia Antonio , La Torre Giuseppe
Published: March 2012

Objectives. To assess the influence of sociodemographic factors on smoking habits in Italy and if an interaction exists between these variables.Methods. Data from the national survey “Health Conditions and Healthcare Services Use” in 2005 were used. The independent association between tobacco smoking and sociodemographical variables was assessed using logistic regression analysis. Interactions between variables were investigated calculating the synergism index (SI).Results. Sample population consists of 109.829 subjects (over 15 years). 21.9% are current and 21.8% are former smokers. Current smokers are mostly 45–54-years old males, from Central Italy, unemployed, divorced or separated but having a good health status without chronic medical conditions. Ever smokers are mostly 45–54 years old males, from Northeast Italy, unemployed, with chronic conditions. People with a university degree and with a good household income have the lowest OR for both conditions. A synergistic effect was found between marital status and educational level (for ever smokers SI = 1.96; for current smokers SI = 1.67).Conclusions. Smoking is prevalent in lower socioeconomic groups and there is the strong need to increase social, economic and cultural capital in order to reduce it.
The Need for a Specific Risk Prediction System in Native Valve Infective Endocarditis Surgery
Authors: De Feo Marisa , Cotrufo Maurizio , Carozza Antonio , De Santo Luca S. , Amendolara Francesco , Giordano Salvatore , Della Ratta Ester E. , Nappi Gianantonio , Della Corte Alessandro
Published: March 2012

The need for a specific risk score system for infective endocarditis (IE) surgery has been previously claimed. In a single-center pilot study, preliminary to future multicentric development and validation, bivariate and multivariate (logistic regression) analysis of early postoperative mortality predictors in 440 native valve IE patients were performed. Mathematical procedures assigned scores to the independent predictors emerged (AUC of the ROC curve: 0.88). Overall mortality was 9.1%. Six predictors were identified and assigned scores, including age (5–13 points), renal failure (5), NYHA class IV (9), critical preoperative state (11), lack of preoperative attainment of blood culture negativity (5), perivalvular involvement (5). Four risk classes were drawn ranging from “very low risk” (≤5 points, mean predicted mortality 1%), and to “very high risk” (≥20 points, 43% mortality). IE-specific risk stratification models are both needed, as disease-specific factors (e.g., cultures, abscess), beside the generic ones (e.g., age, renal impairment) affect mortality, and feasible.
Use of Spineless Cactus (Opuntia ficus indica f. inermis) for Dairy Goats and Growing Kids: Impacts on Milk Production, Kid's Growth, and Meat Quality
Authors: Mahouachi M. , Atti N. , Hajji H.
Published: March 2012

The objective of this study was to determine the effect of spineless cactus incorporation in food of dairy goats and growing kids on milk production and composition and on kid's growth and meat characteristics. Two experiments were conducted on Tunisian local goats. In the first, 30 females were divided into two groups; goats of Control group were reared on grazing pasture receiving indoor 0.5 kg of hay and 0.4 kg of concentrate. Goats for the second group (Cac-FL) were kept in feedlot and fed cactus ad libitum more 0.5 kg of hay and 0.4 kg of concentrate. In the second experiment, 14 kids were divided into 2 groups receiving 600 g of hay. The Control group received ad libitum a concentrate containing 130 g crude protein (CP) per kg of dry matter. The second group received cactus ad-libitum plus the half concentrate quantity of control one with 260 g CP/kg DM (Cactus). The daily milk production averaged 485 ml for Control group and 407 ml for Cac-FL one. The milk fat content was significantly higher for Control than Cac-FL group. In the second experiment, animals in Control and Cactus groups had similar growth rate. Carcass fat was significantly lower in Cactus than in the Control group. Cactus in the diet was associated with more C18:2 and conjugated linoleic acid as well as a higher proportion of PUFA than Control ones.
A Refined Methodology for Defining Plant Communities Using Postagricultural Data from the Neotropics
Authors: Myster Randall W.
Published: March 2012

How best to define and quantify plant communities was investigated using long-term plot data sampled from a recovering pasture in Puerto Rico and abandoned sugarcane and banana plantations in Ecuador. Significant positive associations between pairs of old field species were first computed and then clustered together into larger and larger species groups. I found that (1) no pasture or plantation had more than 5% of the possible significant positive associations, (2) clustering metrics showed groups of species participating in similar clusters among the five pasture/plantations over a gradient of decreasing association strength, and (3) there was evidence for repeatable communities—especially after banana cultivation—suggesting that past crops not only persist after abandonment but also form significant associations with invading plants. I then showed how the clustering hierarchy could be used to decide if any two pasture/plantation plots were in the same community, that is, to define old field communities. Finally, I suggested a similar procedure could be used for any plant community where the mechanisms and tolerances of species form the “cohesion” that produces clustering, making plant communities different than random assemblages of species.
Possible Therapeutic Use of Spermatogonial Stem Cells in the Treatment of Male Infertility: A Brief Overview
Authors: Vlajković Slobodan , Čukuranović Rade , Daković Bjelaković Marija , Stefanović Vladisav
Published: March 2012

Development of germ cells is a process starting in fetus and completed only in puberty. Spermatogonial stem cells maintain spermatogenesis throughout the reproductive life of mammals. They are undifferentiated cells defined by their ability to both self-renew and differentiate into mature spermatozoa. This self-renewal and differentiation in turn is tightly regulated by a combination of intrinsic gene expression as well as the extrinsic gene signals from the local tissue microenvironment. The human testis is prone to damage, either for therapeutic reasons or because of toxic agents from the environment. For preservation of fertility, patients who will undergo radiotherapy and/or chemotherapy have an attractive possibility to keep in store and afterwards make a transfer of spermatogonial stem cells. Germ cell transplantation is not yet ready for the human fertility clinic, but it may be reasonable for young cancer patients, with no other options to preserve their fertility. Whereas this technique has become an important research tool in rodents, a clinical application must still be regarded as experimental, and many aspects of the procedure need to be optimized prior to a clinical application in men. In future, a range of options for the preservation of male fertility will get a new significance.
Regional Prevalence of Short Stature in Saudi School-Age Children and Adolescents
Authors: El Mouzan Mohammad I. , Al Herbish Abdullah S. , Al Salloum Abdullah A. , Al Omer Ahmad A. , Qurachi Mansour M.
Published: March 2012

Objective. To assess the magnitude of regional difference in prevalence of short stature in Saudi children and adolescents.Subjects and Methods. A representative sample from three different regions of the Kingdom of Saudi Arabia (KSA) (North, Southwest, and Center) was used to calculate the prevalence of short stature (standard deviation score less than-2) in children 5 to 17 years of age.Results. There were 9018 children and adolescents from 5 to 17 years of age (3366, 2825, and 2827 in the Northern, Southwestern and Central regions, resp.) and 51% were boys. In both school-age children and adolescents, there was a significantly higher prevalence of short stature in the Southwestern than in the Northern or the Central region (P< 0.0001).Conclusion. The finding of significant regional variation between regions helps in planning priorities for research and preventive measures.
Removal of Particulate Matter in a Tubular Wet Electrostatic Precipitator Using a Water Collection Electrode
Authors: Kim Jong-Ho , Yoo Hee-Jung , Hwang You-Seong , Kim Hyeok-Gyu
Published: March 2012

As one of the effective control devices of air pollutants, the wet electrostatic precipitator (ESP) is an effective technique to eliminate acid mist and fine particles that are re-entrained in a collection electrode. However, its collection efficiency can deteriorate, as its operation is subject to water-induced corrosion of the collection electrode. To overcome this drawback, we modified the wet ESP system with the installation of a PVC dust precipitator wherein water is supplied as a replacement of the collection electrode. With this modification, we were able to construct a compact wet ESP with a small specific collection area (SCA, 0.83 m2/(m3/min)) that can acquire a high collection efficiency of fine particles (99.7%).
Characterization of the Antibiotic Compound No. 70 Produced byStreptomycessp. IMV-70
Authors: Trenozhnikova Lyudmila P. , Khasenova Almagul K. , Balgimbaeva Assya S. , Fedorova Galina B. , Katrukha Genrikh S. , Tokareva Nina L. , Kwa Boo H. , Azizan Azliyati
Published: March 2012

We describe the actinomycete strain IMV-70 isolated from the soils of Kazakhstan, which produces potent antibiotics with high levels of antibacterial activity. After the research of its morphological, chemotaxonomic, and cultural characteristics, the strain with potential to be developed further as a novel class of antibiotics with chemotherapeutics potential was identified asStreptomycessp. IMV-70. In the process of fermentation, the strainStreptomycesspp. IMV-70 produces the antibiotic no. 70, which was isolated from the culture broth by extraction with organic solvents. Antibiotic compound no. 70 was purified and separated into individual components by HPLC, TLC, and column chromatography methods. The main component of the compound is the antibiotic 70-A, which was found to be identical to the peptolide etamycin A. Two other antibiotics 70-B and 70-C have never been described and therefore are new antibiotics. The physical-chemical and biological characteristics of these preparations were described and further researched. Determination of the optimal growth conditions to cultivate actinomycete-producer strain IMV-70 and development of methods to isolate, purify, and accumulate preparations of the new antibiotic no. 70 enable us to research further the potential of this new class of antibiotics.
Immobilization of Peroxidase onto Magnetite Modified Polyaniline
Authors: Barbosa Eduardo Fernandes , Molina Fernando Javier , Lopes Flavio Marques , García-Ruíz Pedro Antonio , Caramori Samantha Salomão , Fernandes Kátia Flávia
Published: March 2012

The present study describes the immobilization of horseradish peroxidase (HRP) on magnetite-modified polyaniline (PANImG) activated with glutaraldehyde. After the optimization of the methodology, the immobilization of HRP on PANImG produced the same yield (25%) obtained for PANIG with an efficiency of 100% (active protein). The optimum pH for immobilization was displaced by the effect of the partition of protons produced in the microenvironment by the magnetite. The tests of repeated use have shown that PANImG-HRP can be used for 13 cycles with maintenance of 50% of the initial activity.
Diagnostic Value of Dynamic Contrast-Enhanced Magnetic Resonance Imaging in the Evaluation of the Biliary Obstruction
Authors: Bilgin Mehmet , Toprak Hüseyin , Burgazli Mehmet , Bilgin S. Sennur , Chasan Ritvan , Erdogan Ali , Balcı Cem
Published: March 2012

Purpose. In this study, our purpose was to investigate the diagnostic efficacy of the dynamic contrast-enhanced magnetic resonance imaging (MRI) method in the patients with bile duct obstruction.Materials and Methods. 108 consecutive patients (53 men, 55 women, mean age;55.77±14.62, range 18–86 years) were included in this study. All the patients underwent conventional upper abdomen MRI using intravenous contrast material (Gd-DTPA) and MRCP in 1.5 Tesla MRI scanner. MRCP images were evaluated together with the T1 and T2w images, and both biliary ducts and surrounding tissues were examined for possible pathologies that may cause obstruction.Results. MRI/MRCP findings compared with final diagnoses, MRI/MRCP in the demonstration of bile duct obstruction sensitivity 96%, the specificity 100%, and accuracy 96.3%, in the detection of presence and level of obstruction, the sensitivity 96.7%, specificity 100%, and accuracy 97.2%, in the diagnosis of choledocholithiasis, the sensitivity 82.3%, specificity 96%, and accuracy 91.7%, and in the determination of the character of the stenosis, sensitivity 95.6%, specificity 91.3%, and accuracy 94.5% were found.Conclusion. The combination of dynamic contrast-enhanced MRI and MRCP techniques in patients with suspected biliary obstruction gives the detailed information about the presence of obstruction, location, and causes and is a highly specific and sensitive method.