bluuebunny/crossref_metadata_2025 huggingface dataset:
Amperometric Glucose Determination by Means of Glucose Oxidase Immobilized on a Cellulose Acetate Film: Dependence on the Immobilization Procedures
Authors: Portaccio Marianna , Durante Daniela , Viggiano Andrea , Di Martino Silvana , De Luca Paola , Di Tuoro Daniela , Bencivenga Umberto , Rossi Sergio , Canciglia Paolo , De Luca Bruno , Mita Damiano Gustavo
Published: July 2007

Glucose microelectrodes were prepared by immobilizing glucose oxidase onto a cellulose acetate film coating a platinum wire. Hexamethylenediamine (HMDA) and Glutaraldehyde (GA) were employed as spacer and coupling agent, respectively. Sensitivities and linear response ranges were studied as a function of the relative amounts of HMDA and GA. The best sensitivity was found when HMDA and GA were 5% and 2.5% in aqueous solutions, respectively. Taking as a reference the functioning of this biosensor, the roles of HMDA and GA percentages appear to be opposed when the extension of the linear response range is considered. Indeed, an increase of one unit in HMDA percentage (from 5 to 6 %) induces an increase in the extension of the linear response range equal to that obtained with a decrease of one unit of GA percentage (from 2.5 to 1.5%).
Determination of neutral carbohydrates by CZE with direct UV detection
Authors: Rovio Stella , Yli‐Kauhaluoma Jari , Sirén Heli
Published: July 2007

A new CZE method relying on in‐capillary reaction and direct UV detection at the wavelength 270 nm is presented for the simultaneous separation of the neutral carbohydrates xylitol, D‐(−)‐mannitol, sucrose, D‐(+)‐fucose, D‐(+)‐cellobiose, D‐(+)‐galactose, D‐(+)‐glucose, L‐rhamnose, D‐(+)‐mannose, D‐(−)‐arabinose, D‐(+)‐xylose, and D‐(−)‐ribose. The alkaline electrolyte solution was prepared of 130 mM sodium hydroxide and 36 mM disodium hydrogen phosphate dihydrate. Separation of the sample mixture was achieved within 35 min. Calibration plots were linear in the range of 0.05–3 mM. Reproducibility of migration times was between 0.3 and 1.1%, and the detection limits for the analytes were 0.02 and 0.05 mM. The optimized method was applied for the determination of neutral monosaccharides in lemon, pineapple, and orange juices and a cognac sample. The methodology is fast since no other sample preparation except dilution is required.
Guanosine gel for sequence‐dependent separation of polymorphic ssDNA
Authors: Case William S. , Glinert Keren D. , LaBarge Sam , McGown Linda B.
Published: July 2007

The separation of fluorescent‐labeled ssDNA fragments of equal length based on differences in sequence was achieved through the use of guanosine gels (G‐gels) formed by guanosine‐5'‐monophosphate (GMP) in capillary gel electrokinetic chromatography (CGEKC) with LIF detection. Baseline resolution was achieved for homodimers and homopentamers of A, T, and C. G‐gel CGEKC provided better resolution than CZE, MEKC, or a sieving gel in CGE. Resolution improved with increasing GMP, indicating that the interaction is linked to structural organization of the G‐gel. Fluorescence intensity and anisotropy show that the order of interaction with G‐gels is T>C>A. We then investigated four conformationally similar, polymorphic 76‐mers with A/G substitutions that are utilized in forensic DNA typing. Resolution was achieved by CGEKC but not CZE or CGE. In CGEKC, the negatively charged G‐gels and oligonucleotides electromigrate toward the positive inlet while being driven by EOF to the negative outlet. The net forward velocity is the greatest for oligonucleotides most closely associated with the slower, more cumbersome G‐gel network. For the 76‐mers, resolution increases with increasing difference in guanosine content between strands and, for a given difference, with increasing total guanosines in the strands.
A design procedure for tied braced frames
Authors: Rossi Pier Paolo
Published: July 2007

The paper deals with the analysis of the seismic behaviour and design of tied braced frames (TBFs). The behavioural properties of TBFs are described and a comparison drawn with standard eccentrically braced frames. A design procedure is then proposed that aims to achieve optimal collapse seismic behaviour, i.e. a global collapse mechanism characterized by uniform plastic rotations of links. The procedure is based on the displacement‐based approach so as to achieve direct and efficient control of the peak ground acceleration of collapse. Applications are carried out on systems with different numbers of storeys and lengths of links to obtain confirmation of the accuracy of the design hypotheses and methodologies. Copyright © 2007 John Wiley & Sons, Ltd.
On the estimation of hysteretic energy demands for SDOF systems
Authors: Arroyo Danny , Ordaz Mario
Published: July 2007

Based on a statistical study of the dynamic response of single degree of freedom (SDOF) systems subjected to earthquake ground motions, a rule to estimate hysteretic energy demands is proposed. Expressions for elastic–perfectly plastic, stiffness degrading and pinching SDOF systems were obtained. The proposed rule does not explicitly depend on the period of the system; instead, it depends on the elastic pseudo‐acceleration and elastic velocity spectra. It is shown that the proposed rule can be applied to compute hysteretic energy demands for systems located at different soil conditions. In addition, information about scatter and bias of the proposed rule is also presented. Copyright © 2007 John Wiley & Sons, Ltd.
Optimized isolation enables ex vivo analysis of microglia from various central nervous system regions
Authors: De Haas Alexander H. , Boddeke Hendricus W. G. M. , Brouwer Nieske , Biber Knut
Published: July 2007

Ex vivo analysis is an accurate and convenient way to study in vivo microglia phenotype and function. However, current microglia isolation protocols for ex vivo analysis show many differences in isolation steps (perfusion, removal of meninges and blood vessels, mechanical dissociation, enzymatic dissociation, density separation, immunomagnetic separation, and fluorescence‐activated cell sorting), often without addressing their effects on microglia purity, number, phenotype, and function. Therefore, the aim of this study was to provide an optimized isolation protocol with emphasis on microglia purity and number to enable ex vivo analysis of adult mouse microglia. The application of this protocol for ex vivo phenotype and functional analysis is corroborated by results from flow cytometry, gene expression analysis, chemotaxis, and phagocytosis assays. In addition, this study shows the possibility to analyze microglia isolated from various central nervous system regions such as optic nerve, striatum, hippocampus, spinal cord, cerebellum, and cerebral cortex. Furthermore, this is the first study presenting DRAQ5 as a superior alternative to propidium iodide for the discrimination between living and dead cells. DRAQ5 staining facilitated the identification of microglia upon flow cytometry without the need of additional fluorescent markers. Along with a favorable emission spectrum, DRAQ5 proved a valuable tool for flow cytometry of microglia. The presented optimized microglia isolation protocol for ex vivo analysis offers the opportunity to obtain more insight into both general and region‐specific microglia behavior. © 2007 Wiley‐Liss, Inc.
A high-fat diet and regulatory T cells influence susceptibility to endotoxin-induced liver injury
Authors: Ma Xiong , Hua Jing , Mohamood Abdiaziz R. , Hamad Abdel Rahmin A. , Ravi Rajani , Li Zhiping
Published: July 2007

In nonalcoholic fatty liver disease, the pathogenesis of progression from simple steatosis to steatohepatitis has not been fully clarified. Many factors, including oxidative stress and hepatic immune regulation, contribute to the inflammation in steatosis. Because regulatory T cells (Tregs) are important components of immune regulation, we have now investigated their role in the pathogenesis of nonalcoholic steatohepatitis. Wild-type C57BL/6 mice were fed a high-fat (HF) diet to induce steatosis, and the hepatic lymphocyte population was analyzed by flow cytometry. HF-induced steatosis was associated with the depletion of hepatic Tregs and led to up-regulation of the inflammatory tumor necrosis factor-α signaling pathway. When challenged by exogenous lipopolysaccharide, the HF-fed mice developed liver inflammation. In contrast, the adoptive transfer of Tregs decreased inflammation in HF-fed mice. In comparison with effector T cells, Tregs had a lower expression of Bcl-2 and, therefore, increased susceptibility to oxidative stress-induced apoptosis. The treatment of mice with the antioxidant Mn(III)tetrakis(4-benzoic acid)porphyrin chloride reduced Treg apoptosis, increased the number of hepatic Tregs, and decreased hepatic inflammation in HF-fed mice.

Conclusion:

Our results indicate that increased oxidative stress in a fatty liver causes the apoptosis of Tregs, reduces the number of hepatic Tregs, and leads to a lowered suppression of inflammatory responses. This scenario is likely one of the pathogenetic mechanisms that facilitate the transformation of simple steatosis into steatohepatitis when a fatty liver is exposed to second or third hits.
Characteristics of nutrient concentrations during low streamflow in Korean watersheds with paddy fields
Authors: Kim Jin S. , Kwun Soon‐Kuk , Oh Seung Y.
Published: July 2007

We investigated nutrient concentrations, during periods of low streamflow, from medium‐scale watersheds (5.1–15.3 km2) with paddy fields. Data were collected both during irrigation and non‐irrigation periods, from 1996 to 2000. Mean total nitrogen (TN) concentration during irrigation periods (2.6 mg l−1) was significantly lower than during non‐irrigation periods (6.2 mg l−1), most likely due to the dilution effect of higher discharge and nitrogen removal in the forest and paddy field by denitrification. Mean total phosphorus (TP) concentration during irrigation periods (0.13 mg l−1) was higher than during non‐irrigation periods (0.09 mg l−1). Therefore, the mean TN:TP ratio during irrigation periods was 20:1, compared to 67:1 during non‐irrigation periods; hence the possibility of cyanobacterial blooms was higher during the peak of irrigation. During irrigation periods, TN concentrations in the study watersheds displayed no relationship with discharge, similar to the finding for the paddy fields. Paddy field irrigation may impact on nitrogen concentrations in low streamflow at the watershed scale. Copyright © 2007 John Wiley & Sons, Ltd.
Daxx contains two nuclear localization signals and interacts with importin α3
Authors: Yeung Percy Luk , Chen Liuh‐Yow , Tsai Shih‐Chieh , Zhang Aihua , Chen J. Don
Published: July 2007

Daxx plays a major role in several important signaling pathways including transcription and cell death. It has been postulated that Daxx regulates both events from the nucleus; however, the mechanism by which Daxx is localized in the nucleus remains obscure. Here we show that nuclear localization of Daxx is controlled by two independent signals and importin 3. Domain analysis reveals that Daxx contains two separate nuclear localizing domains. Site‐directed mutagenesis reveals that the basic aa sequence RLKRK at residues 227–231 (NLS1) is responsible for nuclear localization of N‐terminal domain, while aa sequence KKSRKEKK at residues 630–637 (NLS2) is responsible for nuclear localization of the C‐terminal domain. Mutations of a NLS consensus sequence RKKRR at residues 391–395 and several other basic aa clusters have no effect on Daxx nuclear localization. In full‐length Daxx, NLS1 contributes partially to nuclear localization, while NLS2 plays a major role. Markedly, it is essential to disrupt both NLS1 and NLS2 in order to completely block nuclear localization of the full‐length protein and to prevent its association with PML nuclear bodies. Furthermore, Daxx interacts selectively with importin α3 through its NLS1 and NLS2 sequences. Conversely, importin α3 utilizes two NLS‐binding sites for Daxx interaction, suggesting that the importin/mediates nuclear import of Daxx. Finally, we show that nuclear localization of Daxx is essential for its transcriptional effects on GR and p53. Together, these data unveil a molecular mechanism that controls nuclear localization of Daxx and support a nuclear role of Daxx in transcriptional regulation. J. Cell. Biochem. 103: 456–470, 2008. © 2007 Wiley‐Liss, Inc.
Cellular nucleic acid binding protein binds G‐rich single‐stranded nucleic acids and may function as a nucleic acid chaperone
Authors: Armas Pablo , Nasif Sofía , Calcaterra Nora B.
Published: July 2007

Cellular nucleic acid binding protein (CNBP) is a small single‐stranded nucleic acid binding protein made of seven Zn knuckles and an Arg‐Gly rich box. CNBP is strikingly conserved among vertebrates and was reported to play broad‐spectrum functions in eukaryotic cells biology. Neither its biological function nor its mechanisms of action were elucidated yet. The main goal of this work was to gain further insights into the CNBP biochemical and molecular features. We studied Bufo arenarum CNBP (bCNBP) binding to single‐stranded nucleic acid probes representing the main reported CNBP putative targets. We report that, although bCNBP is able to bind RNA and single‐stranded DNA (ssDNA) probes in vitro, it binds RNA as a preformed dimer whereas both monomer and dimer are able to bind to ssDNA. A systematic analysis of variant probes shows that the preferred bCNBP targets contain unpaired guanosine‐rich stretches. These data expand the knowledge about CNBP binding stoichiometry and begins to dissect the main features of CNBP nucleic acid targets. Besides, we show that bCNBP presents a highly disordered predicted structure and promotes the annealing and melting of nucleic acids in vitro. These features are typical of proteins that function as nucleic acid chaperones. Based on these data, we propose that CNBP may function as a nucleic acid chaperone through binding, remodeling, and stabilizing nucleic acids secondary structures. This novel CNBP biochemical activity broadens the field of study about its biological function and may be the basis to understand the diverse ways in which CNBP controls gene expression. J. Cell. Biochem. 103: 1013–1036, 2008. © 2007 Wiley‐Liss, Inc.
The Role of heat shock protein 27 in extravillous trophoblast differentiation
Authors: Matalon S. Tartakover , Drucker L. , Fishman A. , Ornoy A. , Lishner M.
Published: July 2007

Trophoblast cells from placental explants differentiate in culture to extravillous trophoblast cells (EVT cells). During trophoblast differentiation heat‐shock‐protein‐27 (HSP27) mRNA and multidrug‐resistance‐protein‐5 (MRP5, transporter of cyclic nucleotides) expression are increased. HSP27 is a regulator of actin filaments structure and dynamic, has a role in cell differentiation and may affect NF‐kB activity. In this study we aimed to assess HSP27 level in trophoblast cells and its correlation with motility and differentiation related processes [MMPs activity, nitric oxide (NO), inducible nitric oxide synthase (iNOS), proliferation and MRP5 levels]. We evaluated HSP27 expression in a first trimester human trophoblast explants model designed to assess EVT cells differentiation/migration with/without 6‐mercaptopurine (6MP, an EVT inhibitor of migration). We found that HSP27 level is expressed in the nucleous and cytoplasm of non‐proliferting villous‐trophoblast cells (negative for Ki67) and in the cell periphery and cytoplasm of motile EVT cells. Moreover, 6MP decreased HSP27 nucleous expression that was associated with inhibited MMP2 activity and NO production. Also decreased iNOS expression and increased MRP5 mRNA levels were observed. In conclusion, HSP27 expression is modulated in concordance with migration dependent parameters in trophoblast cells. J. Cell. Biochem. 103: 719–729, 2008. © 2007 Wiley‐Liss, Inc.
Aneuploidy and cancer
Authors: Chi Ya‐Hui , Jeang Kuan‐Teh
Published: July 2007

The cell's euploid status is influenced by, amongst other mechanisms, an intact spindle assembly checkpoint (SAC), an accurate centrosome cycle, and proper cytokinesis. Studies in mammalian cells suggest that dysregulated SAC function, centrosome cycle, and cytokinesis can all contribute significantly to aneuploidy. Of interest, human cancers are frequently aneuploid and show altered expression in SAC genes. The SAC is a multi‐protein complex that monitors against mis‐segregation of sister chromatids. Several recent experimental mouse models have suggested a link between weakened SAC and in vivo tumorigenesis. Here, we review in brief some mechanisms which contribute to cellular aneuploidy and offer a perspective on the relationship between aneuploidy and human cancers. J. Cell. Biochem. 102: 531–538, 2007. © 2007 Wiley‐Liss, Inc.
Histone deacetylases in control of skeletogenesis
Authors: Westendorf Jennifer J.
Published: July 2007

Skeletogenesis occurs continuously during the lifespan of vertebrate organisms. In development, the skeleton is patterned and modeled until each bone achieves its optimal shape and full size. During adults, the skeleton is remodeled to maintain strength and release calcium. The bone‐resorbing and bone‐forming activities of osteoclasts and osteoblasts, respectively, are tightly coupled to maintain optimal skeletal health; however, during aging and disease, these cells can become uncoupled, adversely affecting skeletal health and strength. Histone deacetylases have emerged as important regulators of endochondral bone formation, osteoblast maturation and osteoclast survival. Histone deacetylases are inhibited by small molecules that are approved and/or in clinical trials as cancer therapeutic drugs or anti‐epileptic agents. In this article, the roles of histone deacetylases and effects of histone deacetylase inhibitors on bone and cartilage cells are reviewed. J. Cell. Biochem. 102: 332–340, 2007. © 2007 Wiley‐Liss, Inc.
Light and transmission electron microscopy study of the peripheral olfactory organ of the guppy, Poecilia reticulata (Teleostei, Poecilidae)
Authors: Lazzari Maurizio , Bettini Simone , Ciani Franco , Franceschini Valeria
Published: July 2007

A study of the peripheral olfactory organ, with special attention to the olfactory epithelium, has been carried out in the guppy (Poecilia reticulata). Guppy is well known to have a vision‐based sexual behavior. The olfactory chamber caudally opens directly in an accessory nasal sac, which is bent medially and gives rise to two recesses that can be considered secondary accessory nasal sacs, antero‐medial and postero‐medial, respectively. The sensory epithelium, which lines only the medial wall of the nasal cavity, is basically flat rising in a very low lamella only in the posterior part. The olfactory receptors are not evenly distributed in the olfactory mucosa, but aggregate in shallow folds separated by epithelial cells with evident microridges. Ciliated olfactory sensory neurons and microvillous olfactory sensory neurons are clearly identified by transmission electron microscopy (TEM). Scarce crypt olfactory neurons are found throughout the sensory folds. The nasal sacs indicates the capacity to regulate the flow of odorant molecules over the sensory epithelium, possibly through a pump‐like mechanism associated with gill ventilation. The organization of the olfactory organ in guppy is simple and reminds what is found in early posthatching stages of fish which at the adult state have a well developed olfactory organ. This simple organization supports the idea that the guppy rely on olfaction less than other fish species provided with more extended olfactory receptorial surface. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Polarized light imaging of white matter architecture
Authors: Larsen Luiza , Griffin Lewis D. , GRäßel David , Witte Otto W. , Axer Hubertus
Published: July 2007

Polarized light imaging (PLI) is a method to image fiber orientation in gross histological brain sections based on the birefringent properties of the myelin sheaths. The method uses the transmission of polarized light to quantitatively estimate the fiber orientation and inclination angles at every point of the imaged section. Multiple sections can be assembled into a 3D volume, from which the 3D extent of fiber tracts can be extracted. This article describes the physical principles of PLI and describes two major applications of the method: the imaging of white matter orientation of the rat brain and the generation of fiber orientation maps of the human brain in white and gray matter. The strengths and weaknesses of the method are set out. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Method of imaging low density lipoproteins by atomic force microscopy
Authors: Chouinard Julie A. , Khalil Abdelouahed , Vermette Patrick
Published: July 2007

This short paper reports a simple method to image low density lipoproteins (LDL) using atomic force microscopy (AFM). This instrument allows imaging of biological samples in liquid and presents the advantage of needing no sample preparation such as staining or fixation that may affect their general structure. Dimensions (diameter and height) of individual LDL particles were successfully measured. AFM imaging revealed that LDL have a quasi‐spherical structure on the x and y axis with an oblate spheroid structure in the z axis (i.e., height). LDLs were found to have an average diameter of 23 ± 3 nm. The obtained mean height was 10 ± 2 nm. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Surface damage induced by FIB milling and imaging of biological samples is controllable
Authors: Drobne Damjana , Milani Marziale , Lešer Vladka , Tatti Francesco
Published: July 2007

Focused ion beam (FIB) techniques are among the most important tools for the nanostructuring of surfaces. We used the FIB/SEM (scanning electron microscope) for milling and imaging of digestive gland cells. The aim of our study was to document the interactions of FIB with the surface of the biological sample during FIB investigation, to identify the classes of artifacts, and to test procedures that could induce the quality of FIB milled sections by reducing the artifacts. The digestive gland cells were prepared for conventional SEM. During FIB/SEM operation we induced and enhanced artifacts. The results show that FIB operation on biological tissue affected the area of the sample where ion beam was rastering. We describe the FIB‐induced surface major artifacts as a melting‐like effect, sweating‐like effect, morphological deformations, and gallium (Ga+) implantation. The FIB induced surface artifacts caused by incident Ga+ ions were reduced by the application of a protective platinum strip on the surface exposed to the beam and by a suitable selection of operation protocol. We recommend the same sample preparation methods, FIB protocol for milling and imaging to be used also for other biological samples. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Single‐ and two‐photon spectral imaging of intrinsic fluorescence of transformed human hepatocytes
Authors: Rajwa Bartek , Bernas Tytus , Acker Helmut , Dobrucki Jurek , Robinson J.P.
Published: July 2007

Autofluorescence (AF) originating from the cytoplasmic region of mammalian cells has been thoroughly investigated; however, AF from plasma membranes of viable intact cells is less well known, and has been mentioned only in a few older publications. Herein, we report results describing single‐ and two‐photon spectral properties of a strong yellowish‐green AF confined to the plasma‐membrane region of transformed human hepatocytes (HepG2) grown in vitro as small three‐dimensional aggregates or as monolayers. The excitation–emission characteristics of the membrane AF indicate that it may originate from a flavin derivative. Furthermore, the AF was closely associated with the plasma membranes of HepG2 cells, and its presence and intensity were dependent on cell metabolic state, membrane integrity and presence of reducing agents. This AF could be detected both in live intact cells and in formaldehyde‐fixed cells. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Authentication of the 31 species of toxic and potent Chinese Materia medica (T/PCMM) by microscopic technique, part 1: Three kinds of toxic and potent animal CMM
Authors: Xia Li , Bai Li‐Ping , Yi Ling , Liu Bin‐Bin , Chu Chu , Liang Zhi‐Tao , Li Ping , Jiang Zhi‐Hong , Zhao Zhong‐Zhen
Published: July 2007

Microscopic authentication is an effective method for quality control of Chinese Materia Medica (CMM) because of its speed, convenience and low cost. However, the application of modern microscopic technique in quality evaluation of Toxic and Potent Chinese Materia Medica (T/PCMM) of animal origin is seldom reported. This gap in published knowledge is increasingly serious because confusion in T/PCMM has led to serious medical problems in China and other countries in recent years. To ensure the safe and effective use of T/PCMM, an accurate and convenient method, based on macroscopic and microscopic techniques, was developed for the authentication of animal T/PCMM. The color microscopic photos of the crude drug were acquired with the light microscope, and from these their morphological and microscopic characters were described. The present method was successfully applied in the analysis of 31 T/PCMM including 17 samples originating from plants, 3 from animals, 9 from minerals, and the remaining 2 from secreta. The macro‐ and microscopic characters of three animal T/PCMM, namely Mylabris (Mylabris phalerata or Mylabris cichorii), Huechys (Huechys sanguinea), and Lytta (Lytta caraganae) were conclusively determined and are here presented. The results demonstrated that it was feasible to use the present microscopic characters for the authentication of the above three animal T/PCMM. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Construction and evaluation of a wavelet‐based focus measure for microscopy imaging
Authors: Xie Hui , Rong Weibin , Sun Lining
Published: July 2007

Microscopy imaging can not achieve both high resolution and wide image space simultaneously. Autofocusing is of fundamental importance to automated micromanipulation. This article proposes a new wavelet‐based focus measure, which is defined as a ratio of high frequency coefficients and low frequency coefficients. 8 series of 49 microscope images each acquired under five magnifications are used to comprehensively compare the performance of our focus measure with the classic and popular focus measures, including Normalized Variance, Entropy, Energy Laplace and wavelet‐based high frequency focus measures. The robustness of these focus measures is evaluated using noisy image sequences corrupted by Gaussian white noise with standard deviations (STD) 5 and 15. An evaluation methodology is proposed, based on which these 5 focus measures are ranked. Experimental results show that the proposed focus measure can provide significantly the best overall performance and robustness. This focus measure can be widely applied to the automated biological and biomedical applications. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Processing of soft pupae and uneclosed pharate adults of Drosophila for scanning electron microscopy
Authors: Beňo Milan , Liszeková Denisa , Farkaš Robert
Published: July 2007

For over four decades, scanning electron microscopy (SEM) has been used in research involving Drosophila genetics and developmental biology. It allows for observation and documentation of the gross morphology of exoskeletal structures as well as their characterization at very high resolution. In most cases, SEM in Drosophila has been limited to imaging adult heads, thoraces, appendages, and embryos, as these structures are relatively hard and/or easy to process for SEM. In contrast, the structures of the pharate adult stages are difficult to prepare for SEM because their integument is quite soft, they are extremely dirty and they are resistant to the usual processing methods. Here, we present an innovative method to prepare these types of structures. Our protocol efficiently removes extraneous material originating from the exuvial fluid of pharate adults and uses a hydrophobic expansion step to keep the soft exoskeleton of the body inflated. In addition to using immersion fixation, it utilizes fixation within the body that occurs via a reaction between osmium tetroxide and alcohols that are infiltrated into the body during a hydrophobic expansion step. This novel approach results in a properly inflated integument that retains its shape in subsequent procedures. Our method provides a useful, general alternative for processing difficult samples, including soft, biological “whole‐mount” specimens and samples that are extremely dirty or resistant to fixative penetration. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Evaluation of quantitative procedures for X‐ray microanalysis of environmental particles
Authors: Choël M. , Deboudt K. , Flament P.
Published: July 2007

Scanning electron microscopy combined with energy‐dispersive X‐ray spectrometry is particularly suited to characterizing morphology and elemental composition of individual microparticles. Although not straightforward, quantitative X‐ray microanalysis of low‐Z‐containing particles is achievable using atmospheric thin‐window X‐ray detectors. A critical aspect of light element analysis is the choice of substrate material. In this work, particles were deposited on specially developed boron substrates. Three case studies were investigated successively in the order of increasing difficulty. Firstly, hundreds of calcium carbonate (CaCO3) particles ranging in size from 0.3 to 10 μm were analyzed. Three quantitative procedures were tested: the “k‐ratio” method, conventional ZAF correction, and Monte Carlo simulations. Average relative errors obtained by the reverse Monte Carlo quantitative program named CASINO were better than 2.5 wt %, carbon included. Secondly, further evaluation was carried out on a finely crushed biotite mineral, containing more than nine elements. Finally, airborne particulate matter, consisting of a complex heterogeneous mixture of particles, was investigated. By applying the Monte Carlo quantitative procedure, the observed particles were easily classified into particle types. Pure compounds (e.g., CaSO4·2H2O, SiO2, CaCO3, etc) were directly assigned according to stoichiometry. In some cases (marine‐derived particles), a partial reactivity of atmospheric particles was demonstrated by quantitative analysis. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
A novel approach for the construction of multiple shRNA expression vectors
Authors: Gou Deming , Weng Tingting , Wang Yang , Wang Zhixin , Zhang Honghao , Gao Li , Chen Zhongming , Wang Pengcheng , Liu Lin
Published: July 2007

The application of RNA interference (RNAi) as a research and therapeutic tool depends on its ability to silence genes in a sequence‐specific manner. Recent studies have reported that the effective knockdown of genes can be achieved by multiple short hairpin RNAs (shRNAs) in a single vector. Moreover, this approach can depress several genes simultaneously. However, current methods for the construction of multiple shRNA vectors often suffer from vector instability and are time‐consuming. Here, we describe a simple, quick and low‐cost approach to construct a single vector expressing four shRNA sequences driven by four different promoters. Using this vector, we were able to improve the gene silencing efficiency and make it possible to silence four different genes simultaneously, further expanding the application spectrum of RNAi, both in functional studies and therapeutic strategies. Copyright © 2007 John Wiley & Sons, Ltd.
Determination of trace levels of dinitrophenolic compounds by microporous membrane liquid–liquid extraction in environmental water samples
Authors: Bartolomé Luis , Lezamiz Jon , Etxebarria Néstor , Zuloaga Olatz , Jönsson Jan Åke
Published: July 2007

A fast and simple hollow fibre‐based microporous membrane liquid–liquid extraction (MMLLE) method is proposed for the determination of trace levels of dinitrophenolic compounds in water samples. The optimization step was performed using a three‐variables Doehlert matrix design, involving the fibre length, the quantity of trioctylphosphine oxide (TOPO) in the acceptor phase and the extraction time. Using the established experimental conditions, some other parameters such as stirring speed, salt content, humic acids and different organic solvents as the acceptor phase were studied. Validation of the method included calibration experiments, linearity studies and determination of method LOD (MLD). The RSD was around 11% in all the experiments on different days at different concentrations. Separation and detection of four dinitrophenols were performed in 10 min with an RP‐LC and a C8 column ACN–citric buffer gradient elution and diode array detection.
Managed socialization: how smart companies leverage global knowledge
Authors: Moitra Deependra , Kumar Kuldeep
Published: July 2007

Driven by economic and market forces, the last 2 decades have witnessed a phenomenal acceleration in the pace of globalization. Today, globalization, and particularly globalization of knowledge work, has emerged as a business necessity. In their quest for competitiveness, more and more companies are leveraging global resources by distributing knowledge work across borders and essentially establishing around‐the‐clock innovation engines. Yet, managing knowledge—the most valuable resource of the new economy enterprises—remains to be a formidable business challenge to deal with. This challenge assumes even greater complexity in the context of globalization, characterized by distance, language barriers, cultural diversity, and a host of other socio‐political factors. Whilst there have been considerable developments in the discipline of knowledge management, much of that does not quite alleviate the struggle companies face in effectively harnessing global knowledge. Specifically, while much progress has been made in managing explicit knowledge, firms find it hard to capture and leverage the tacit knowledge, which holds the key to knowledge‐based competition.

This paper argues that this inability to capitalize on the tacit knowledge stems from a missing ‘social’ dimension in the design of knowledge management strategies, which when addressed leads to unleashing the valuable tacit knowledge. Drawing on real‐world research spanning 12 leading companies, in this paper we discussManaged Socialization—the most vital management process for harnessing global knowledge. We argue that only by institutingmanaged socializationfirms can truly succeed in leveraging global knowledge. Toward that, we describe the various elements that constitutemanaged socializationand based on case studies distil actionable insights that firms can capitalize on to fuel their quest for global dominance. Copyright © 2007 John Wiley & Sons, Ltd.
Knowledge creation and transfer in a cross‐cultural context—empirical evidence from Tyco Flow Control
Authors: Kohlbacher Florian , Krähe Michael O. B.
Published: July 2007

The capability of multinational corporations (MNCs) to create and efficiently combine knowledge from different locations around the world is becoming increasingly important as a determinant of competitive advantage and will be more and more critical to their success and survival. Consequently, cultural differences and cross‐cultural contexts play an essential role for and significantly influence global knowledge creation and management. This paper presents a case study resulting from a current empirical research project on knowledge management and the transfer of knowledge within organizations of MNCs. We describe and analyze the efforts of global market leader Tyco Flow Control (TFC)'s Japanese subsidiary KTM to transfer relevant—and often highly tacit—knowledge to a newly acquired production site in Taiwan. Challenges and difficulties encountered in the process of global knowledge management—in this case the transfer of knowledge from Japan to Taiwan—as well as the creation of new knowledge locally and its feedback—are illustrated and carefully examined. Finally, we discuss our findings and highlight practical implications for managers and international corporations in a global business environment. Copyright © 2007 John Wiley & Sons, Ltd.
Knowledge management and global cultures: elucidation through an institutional knowledge‐flow perspective
Authors: Nissen Mark E.
Published: July 2007

Knowledge—particularly tacit knowledge—is key to sustainable competitive advantage. This applies especially to the current competitive environment of increasing globalization. As global organizations engage in increasing levels of intercultural interaction—across continents, nations, organizations, races, religions, norms, and customs—intercultural differences can impede knowledge flows, and hence degrade competitive performance. Managing such knowledge flows—diagnosing and dissolving intercultural knowledge clumps and clots that impede healthy circulation—represents a critical priority in this competitive, global environment, but the sets of knowledge management (KM) theories and analytical lenses available to most leaders and managers remain limited in terms of managing intercultural knowledge flows. Alternatively, Institution Theory and institutional analysis offer excellent promise to elucidate important aspects of globalization, and can be very helpful with understanding cultural change. The problem is, Institution Theory does not address knowledge flows well at present; hence its elucidatory potential in this light remains opaque. In this expository article, we integrate emerging Knowledge‐Flow Theory with established Institution Theory, and use this multidisciplinary perspective to develop new insight into how knowledge flows can be managed across global organizations and intercultural contexts. The use and utility of this new theoretical perspective are illustrated through examination of a current, global, engineering project that involves intercultural interaction. Results provide actionable guidance for the global manager, in addition to compelling topics for future research along these lines. Copyright © 2007 John Wiley & Sons, Ltd.
Effect of land use on some soil properties related to the risk of loss of soil phosphorus
Authors: Troitiño F. , Gil‐Sotres F. , Leirós M.C. , Trasar‐Cepeda C. , Seoane S.
Published: July 2007

Although land use clearly modifies soil properties, the intensity of the modifications depends on the management procedures and also on the soil properties themselves. To enable construction of models that describe soil nutrient losses, extensive databases corresponding to soils under different land use must be made available. Analysis of 404 samples of soils (from Galicia, NW Spain), under different types of use revealed that most of the soil properties underwent changes in the following order: forest use (least modified) ‐ grassland ‐ arable (most modified). Decreases in the contents of organic matter, extractable oxides and P‐adsorption capacity followed the same order, as did increases in the contents of available P (total, inorganic and organic), P desorbed with distilled water, and degree of P saturation. In general, in all of the soils, independently of their use, the amount of P desorbed (whether total P, molybdate reactive P or particulate P) was more closely related to the degree of P saturation than to the levels of P extracted with bicarbonate. Copyright © 2007 John Wiley & Sons, Ltd.
Why do prices rise faster than they fall? With an application to mortgage rates
Authors: Toolsema Linda A. , Jacobs Jan P. A. M.
Published: July 2007

Empirical literature shows that prices respond asymmetrically to cost changes in many markets, rising faster than falling. An example is the mortgage rate, which follows an increase in capital market rates faster than a decrease. We examine various theoretical explanations for asymmetric price adjustments in general and discuss their validity for the mortgage rate. We show that in The Netherlands mortgage rates indeed respond asymmetrically to changes in capital market rates and consider the relevance of theoretical explanations for this particular market. Copyright © 2007 John Wiley & Sons, Ltd.
A synthetic aperture radar‐based focusing algorithm for B‐scan ground penetrating radar imagery
Authors: Yigit Enes , Demirci Sevket , Ozdemir Caner , Kavak Adnan
Published: July 2007

In the classical B‐Scan ground penetrating radar (GPR) imagery, unprocessed image domain data exhibit undesired hyperbolic effects and therefore have low resolution features. To solve this problem, various focusing or migration techniques have been developed and applied to focus the scattered energy at their true spatial locations in the object space. In this article, we present a synthetic aperture radar (SAR) based focusing algorithm to obtain well‐localized two‐dimensional B‐scan GPR images of various buried objects. The concept and the formulation of our frequency domain based imaging algorithm are presented. The performance of the algorithm is tested with both the simulated and measurement data. The simulation data are generated by a physical optics shooting and bouncing ray (PO‐SBR) technique code; whereas the C‐band measured data are collected via an experimental set‐up for different ground environments. Almost perfect focusing performance is achieved for the simulated GPR images. Similarly, well‐focused GPR images with high lateral resolutions are also obtained for the measurement data from metallic and non‐metallic buried objects. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2534–2540, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22724
A coplanar waveguide on‐chip RF choke for WLAN RF circuits
Authors: Kavlak Canan , Gurbuz Yasar , Tekin Ibrahim
Published: July 2007

A novel on‐chip RF choke at 5 GHz is designed and measured for a class A operating Wireless LAN RF power amplifier (PA). The coplanar waveguide (CPW)‐based on‐chip RF choke is implemented as an alternative component to inductors provided by the 0.35‐μm SiGe BiCMOS technology. The CPW RF choke is designed at 5 GHz, and has a length of 1600 μm and loaded with a capacitance of 0.95 pF. The measured impedance of the RF choke at 5 GHz is around 104 Ω. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2530–2534, 2007; Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.22725
Dual‐band operation of an electromagnetic band‐gap patch antenna
Authors: Wang Xiaojing , Hao Yang
Published: July 2007

In this article, a novel concept of electromagnetic band‐gap (EBG) antenna is proposed: dual/multiple band antenna resonances can be achieved using a single patch radiator based on layered EBG substrates. The generalized design procedure is presented. Experimental results demonstrate good agreement with the theoretical prediction and numerical results. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2454–2458, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22728
Tunable first‐order differential group delay generation using a uniform fiber Bragg grating
Authors: Viegas D. , Pinto N. M. P. , Romero R. , Frazão O. , Costa A.
Published: July 2007

Differential group delay (DGD) generation by inducing birefringence in uniform fiber Bragg gratings (FBG) is studied. Applying a transverse load, a birefringence is induced on a uniform FBG creating a tunable differential group delay. A theoretical behavior of this phenomenon is presented being in good agreement with the experimental results obtained. A maximum experimental tunable DGD of ∼60 ps was obtained with this induced birefringent process in the uniform FBG. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2451–2454, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22729
A planar dipole array formed by small resonant particles
Authors: Englund M. , Viitanen A.
Published: July 2007

In this article the complex interaction constant of an infinite planar dipole array is presented. The imaginary part can be expressed in a closed form and the real part can be formulated in a rapidly convergencing manner using the Poisson summation and the Fourier transformation. At a certain frequencies a resonator can be realized loading the dipole inclusions. Inductive, series resonance, and parallel resonance electric circuit loads are considered. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2419–2422, 2007; Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.22730
Ultra wideband filter design based on composite right‐/left‐handed transmission line
Authors: Li Bin , Dai Xi‐Wang , Wu Bian , Liang Chang‐Hong
Published: July 2007

A novel design method of ultra wideband filter based on the composite right‐/left‐handed transmission line theory is presented in this article. Defected ground structure and microstrip interdigital capacitor are introduced to satisfy the necessity of ultra wideband (UWB) filter. A four‐cell composite right/left‐handed UWB filter is fabricated and measured. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2379–2381, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22733
Negative refraction from balanced quasi‐planar chiral inclusions
Authors: Marqués Ricardo , Jelinek Lukas , Mesa Francisco
Published: July 2007

This work proposes a quasi‐planar chiral resonator suitable for the design of negative refractive index metamaterials. It is presented as an analytical model to determine the metamaterial polarizabilities, which is also the basis of a further study of the viability of negative refraction in chiral and racemic arrangements of inclusions made up with the proposed quasi‐planar chiral resonator. The present analysis is expected to pave the way for the design and building of feasible negative refractive index metamaterials whose inclusions can be manufactured by means of standard photo‐etching techniques. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2606–2609, 2007; Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.22736
Injection‐locked GaInp/GaAs HBT frequency divider with stacked transformers
Authors: Wei Hung‐Ju , Meng Chinchun , Chang YuWen , Huang Guo‐Wei
Published: July 2007

The first integrated GaInP/GaAs heterojunction bipolar transistor (HBT) injection‐locked frequency divider (ILFD) with the stacked transformers is demonstrated around 10 GHz. The stacked transformers formed by only two metal layers provide the inductive coupling in the cross feedback and separate biasing for base and collector to allow for the larger output swing in the LC tank and obtaining wide locking range. Under the supply voltage of 5 V and core power consumption of 20.5 mW, the locking range is 7.8% of the center operating frequency. The chip size of the entire ILFD including probing pads is 1.0 × 1.0 mm2. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2602–2605, 2007; Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.22737
Experimental investigation of photonic millimeter‐wave, beam‐splitter‐type coupler in image guide technology
Authors: Fickenscher Thomas
Published: July 2007

Optical control of the coupling characteristics of beam‐splitter‐type directional couplers in image guide technology is investigated experimentally at W‐band. A highly resistive thin silicon lamella is used as a photosensitive beam splitter inside a rectangular junction of two image guides with dielectric strips made of quartz. Measurement results are compared with theory based on a combined approach of the effective dielectric constant method and geometrical optics assuming a uniform photoinduced plasma density inside the semiconductor lamella. The coupling of the device can be controlled optically from about 10 to 23 dB with a variation of less than 2 dB across the whole W‐band. Apart from the application as a directional coupler with controllable coupling characteristics the structure can be used as a cross‐over switch. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2526–2530, 2007; Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.22740