bluuebunny/crossref_metadata_2025 huggingface dataset:
Transient flexural vibrations of an elastic column supported by an elastic half‐space
Authors: Wada H.
Published: March 2007

An analysis is presented of the transient flexural vibrations of an elastic column supported by an elastic half‐space under the condition that an arbitrarily shaped free‐field lateral acceleration and displacement are given as inputs. Applying Laplace transformations with respect to time and numerical inverse Laplace transformations, the time histories of the column acceleration at the interface and free end, and the column and half‐space displacement distributions are obtained. After the input free‐field acceleration terminates, slightly damped and almost harmonically variable acceleration is observed. The acceleration frequency after the disappearance of the input acceleration nearly coincides with the resonant frequency of the system. The slight damping with the first resonant frequency, even if the half‐space is soft compared with the column, is characteristic of the transient flexural vibrations of a column supported by a half‐space. Such a phenomenon is not typical of the transient longitudinal vibration problem. Therefore, it may be concluded: when buildings and structures are subjected to an earthquake or an explosive force, their flexural vibrations will continue with their first resonant frequencies, even if their foundations are soft.
Temporal‐spatial dynamics in oligodendrocyte and glial progenitor cell numbers throughout ventrolateral white matter following contusion spinal cord injury
Authors: Rabchevsky Alexander G. , Sullivan Patrick G. , Scheff Stephen W.
Published: March 2007

The aim of this study was to systematically determine the spatial distribution of oligodendrocytes (CC1+) and glial progenitor cells (NG2+) throughout the ventral lateral funiculi (VLF) of adult rat thoracic spinal cord white matter over the course of spontaneous hindlimb locomotor recovery following moderate contusion injury. We used the optical fractionator technique to establish an unbiased estimate of total CC1+ and NG2+ cell numbers throughout equivalent segments of VLF from normal and injured spinal cords at designated time points. The results demonstrated a greater than 60% loss of oligodendrocytes and a 50% increase in NG2+ cells 2 days postinjury. Subsequently, there was a significant increase in oligodendrocytes 7 days postinjury that continued throughout the time course of our experiments (42 days) when the total numbers recovered to 80% of controls. Conversely, NG2+ cell numbers progressively declined after 2 days postinjury but remained significantly higher than controls throughout the experiments. The pattern of acute loss and repopulation of oligodendrocytes in the VLF paralleled the initial recovery of hindlimb weight‐bearing function. Whether such improvement is directly related to NG2+ cell differentiation into functional oligodendrocytes is uncertain. However, of critical importance is that significant cellular dynamics occurred primarily distal to the injury, and these changes were mirrored by significant alterations in the expression of mature myelin proteins. This infers that site‐specific genetic or cellular interventions designed to enhance locomotor recovery by fostering remyelination of spared and/or newly established relay circuits may need to target not only the injury site but also rostrocaudal regions. © 2007 Wiley‐Liss, Inc.
Positive and negative modulation of word learning by reward anticipation
Authors: Callan Daniel E. , Schweighofer Nicolas
Published: March 2007

Recent evidence from neuroscience indicates that the anticipation of external rewards may enhance declarative memory consolidation by increasing dopaminergic‐modulated plasticity in the hippocampus. A number of studies in psychology, however, have shown that external rewards may have null, or even negative, effects on learning. To shed light on this issue, we developed a novel task, in which native Japanese speakers were rewarded to learn unknown English words inside a functional MRI scanner. Rewards had no effect on recall performance unless we used a rating of reward‐induced anxiety as a covariate. In this case, for highly rewarded words, we found a negative correlation between recall performance and anxiety ratings. For those words, high recall performance and low anxiety ratings were associated with enhanced activity in the midbrain dopaminergic centers, the hippocampus, and the amygdala. On the other hand, low recall performance and high anxiety ratings were associated with enhanced activity in the anterior cingulate and middle frontal gyrus, brain regions that have been shown to be involved with anxiety and divided attention, respectively. A connectivity analysis indicated positive functional connectivity between the midbrain dopaminergic centers and both the hippocampus and the amygdala, as well as negative connectivity between the anterior cingulate and the amygdala. Thus, both our behavioral and imaging results suggest that the anticipation of rewards can, depending on the individual level of reward‐induced anxiety, have either a beneficial effect or a negative effect on word learning. Hum Brain Mapp 2008. © 2007 Wiley‐Liss, Inc.
Structuring the environment to improve outcomes
Authors: Baird Leonard L.
Published: March 2007

The college environment can be changed to promote student progress, but success requires hard thinking and careful planning about six related questions.
improving student outcomes and institutional decision making with PERC
Authors: Palola Ernest G. , Lehmann Timothy
Published: March 2007

A strategy for assessing program effectiveness and its related costs is essential for increasing students' learning outcomes and for making policy decisions. Data collected at Empire State College show how PERC can contribute to the decision‐making process.
A review and preview
Authors: Lenning Oscar T.
Published: March 2007

The potential exists for applying research findings to the improvement of educational outcomes, but continual monitoring of outcomes will be necessary because of changing times.
Cancer cachexia syndrome in head and neck cancer patients: Part II. Pathophysiology
Authors: George Jonathan , Cannon Trinitia , Lai Victor , Richey Luther , Zanation Adam , Neil Hayes D. , Shores Carol , Guttridge Denis , Couch Marion
Published: March 2007

Cancer cachexia is a morbid wasting syndrome common among patients with head and neck cancer. While its clinical manifestations have been well characterized, its pathophysiology remains complex. A comprehensive literature search on cancer cachexia was performed using the National Library of Medicine's PubMed. The Cochrane Library and Google search engine were also used. Recent evidence and new concepts on the pathophysiology of cancer cachexia are summarized. Targeted therapies are presented, and new concepts are highlighted. Cancer cachexia is characterized by complex, multilevel pathogenesis. It involves up‐regulated tissue catabolism and impaired anabolism, release of tumor‐derived catabolic factors and inflammatory cytokines, and neuroendocrine dysfunction. These culminate to create an energy‐inefficient state characterized by wasting, chronic inflammation, neuroendocrine dysfunction, and anorexia. © 2007 Wiley Periodicals, Inc. Head Neck, 2007
Tunisian radish extract (Raphanus sativus) enhances the antioxidant status and protects against oxidative stress induced by zearalenone in Balb/c mice
Authors: Salah‐Abbès Jalila Ben , Abbès Samir , Ouanes Zouhour , Houas Zohra , Abdel‐Wahhab Mosaad A. , Bacha Hassen , Oueslati Ridha
Published: March 2007

Radish (Raphanus sativus) is a food plant known worldwide. From antiquity it has been used in folk medicine as a natural drug against many toxicants. Zearalenone (zen) is a non‐steroidal estrogenic mycotoxin present in corn and food mixture for farm animals and it is hepatotoxic, hematotoxic, immunotoxic, nephrotoxic and genotoxic. The objectives of the present study were to assess the biological activity of radish extract and to evaluate the protective role of radish extract against the toxicity of zen in female Balb/c mice. Animals were divided into seven groups and treated orally for 10 days as follows: a control, an olive oil group, groups treated with radish extract alone (5, 10 and 15 mg kg−1 b.w.), a group treated with zen (40 mg kg−1 b.w.) and a group treated with zen plus the lowest dose of radish extract. The results indicate that radish extract improved the antioxidant status and had no significant effects on hematological and biochemical parameters tested or histology of the liver and kidney. Treatment with zen results in a significant increase in ALT, AST, ALP, BILT, BILD, CRE accompanied with significant changes in most of hematological parameters and the antioxidant enzyme activities, co‐treatment of zen and the radish extract results in a significant reestablishment of hematological, serum biochemical parameters, and the histology of the liver and kidney. These findings suggest that radish extract is safe and can be overcome or, at least, significantly diminish zen effects. Copyright © 2007 John Wiley & Sons, Ltd.
Nondegradable hydrogels for the treatment of focal cartilage defects
Authors: Maher S.A. , Doty S.B. , Torzilli P.A. , Thornton S. , Lowman A.M. , Thomas J.D. , Warren R. , Wright T.M. , Myers E.
Published: March 2007

Nondegradable materials have long been suggested for the treatment of articular cartilage defects; however, the mechanics of the implant/tissue system necessary to ensure long‐term function are unknown. The objective of this study was to explore the performance of nondegradable hydrogel implants in cartilage defects. Our hypothesis was that the structural integrity of the implant and surrounding tissue would be influenced by the compressive modulus of the material used, and that superior results would be obtained with the implantation of a more compliant material. Poly(vinyl alcohol)–poly(vinyl pyrrolidone) hydrogel implants of two different moduli were implanted into osteochondral defects in a rabbit model. Six‐month postoperative histological and mechanical data were used to assess the wear and fixation of the implants. The compliant implants remained well fixed and a thin layer of soft tissue grew over the surface of the implants. However, gross deformation of the compliant implants occurred and debris was evident in surrounding bone. The stiffer implants were dislocated from their implantation site, but with no accompanying evidence of debris or implant deformation. Our hypothesis that superior results would be obtained with implantation of a more compliant material was rejected; a compromise between the wear and fixation properties dependent on modulus was found. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Effects of Vitaxin®, a novel therapeutic in trial for metastatic bone tumors, on osteoclast functions in vitro
Authors: Gramoun Azza , Shorey Seema , Bashutski Jill D. , Dixon S. Jeffrey , Sims Stephen M. , Heersche Johan N. M. , Manolson Morris F.
Published: March 2007

The integrin αvβ3 mediates cell–matrix interactions. Vitaxin®, a humanized monoclonal antibody that blocks human and rabbit αvβ3 integrins, is in clinical trials for metastatic melanoma and prostate cancer. αvβ3 is the predominant integrin on osteoclasts, the cells responsible for bone resorption in health and disease. Here, we report the first investigation of Vitaxin's effects on osteoclast activity. Vitaxin (100–300 ng/ml) decreased total resorption by 50%, but did not alter resorptive activity per osteoclast. Vitaxin (300 ng/ml) decreased osteoclast numbers on plastic by 35% after 48 h. Similarly, attachment after 2 h was reduced by 30% when osteoclasts were incubated with Vitaxin (300 ng/ml) for 25 min prior to plating; however, the rate of fusion of osteoclast precursors in Vitaxin‐treated and control groups was equal. Using time‐lapse microscopy, we evaluated the effect of Vitaxin on osteoclast morphology and found a significant reduction in osteoclast planar area only when cells were pretreated with macrophage colony stimulating factor (M‐CSF). Extracellular Ca2+ and M‐CSF have opposite effects on αvβ3 conformation. Elevation of extracellular Ca2+ eliminated the inhibitory effect of Vitaxin on osteoclast attachment. In contrast, the effect of Vitaxin was enhanced in cells pretreated with M‐CSF. This action of M‐CSF was suppressed by the phosphatidylinositol 3‐kinase (PI3‐kinase) inhibitor wortmannin, suggesting that M‐CSF increases Vitaxin's inhibitory effect by inside‐out activation of αvβ3. In conclusion, Vitaxin decreases resorption by impairing osteoclast attachment, without affecting osteoclast formation and multinucleation. Our data also show that Vitaxin's inhibitory effects on osteoclasts can be modulated by factors known to alter the conformation of αvβ3. J. Cell. Biochem. 102: 341–352, 2007. © 2007 Wiley‐Liss, Inc.
Serum osteopontin, an enhancer of tumor metastasis to bone, promotes B16 melanoma cell migration
Authors: Hayashi Chikako , Rittling Susan , Hayata Tadayoshi , Amagasa Teruo , Denhardt David , Ezura Yoichi , Nakashima Kazuhisa , Noda Masaki
Published: March 2007

Tumor malignancy is associated with several features such as proliferation ability and frequency of metastasis. Since tumor metastasis shortens patients' lifetime, establishment of therapy for anti‐metastasis is very important. Osteopontin (OPN), which abundantly expressed in bone matrix, is involved in cell adhesion, migration, extracellular matrix (ECM) invasion and cell proliferation via interaction with its receptor, that is, αvβ3 integrin. OPN is believed to be a positive regulator of tumor metastasis in vivo. However, how OPN regulates metastasis is largely unknown. Here, we explore the role of OPN in cell migration. Serum from wild‐type mice induced cell migration of B16 melanoma cells, while serum from OPN‐deficient mouse suppressed this event. The presence of recombinant OPN significantly enhanced cell migration compared to albumin containing medium. OPN‐induced cell migration was suppressed by inhibiting the ERK/MAPK pathway indicating that OPN‐induced cell migration depends on this pathway. Overexpression of OPN in these cancer cells per se promoted cell proliferation and tended to increase B16 cell migration suggesting that OPN promotes bone metastasis by playing dual roles both in host microenvironment and in tumor cell itself. In conclusion, the elevated OPN expression in host tissue and tumor cell itself promotes tumor cell migration reading to tumor metastasis, suggesting that neutralization of OPN‐induced signal might be effective in suppression of tumor metastasis. J. Cell. Biochem. 101: 979–986, 2007. © 2007 Wiley‐Liss, Inc.
Renaut bodies in nerves of the trunk of the African elephant, Loxodonta africana
Authors: Witter Kirsti , Egger Gunter F. , Boeck Peter
Published: March 2007

Renaut bodies are loosely textured, cell‐sparse structures in the subperineurial space of peripheral nerves, frequently found at sites of nerve entrapment. The trunk of the elephant is a mobile, richly innervated organ, which serves for food gathering, object grasping and as a tactile organ. These functions of the trunk lead to distortion and mechanical compression of its nerves, which can therefore be expected to contain numerous Renaut bodies. Samples of the trunk wall of an adult African elephant (Loxodonta africana) were examined histologically using conventional staining methods, immunohistochemistry, and lectin histochemistry. Architecture of nerve plexuses and occurrence of Renaut bodies in the elephant trunk were compared with those in tissues surrounding the nasal vestibule of the pig. Prominent nerve plexuses were found in all layers of the elephant trunk. Almost all (81%) nerve profiles contained Renaut bodies, a basophilic, discrete subperineurial layer resembling cushions around the nerve core. In contrast, Renaut bodies were seen in only 15% of nerve profiles in the porcine nasal vestibule. Within Renaut bodies, fusiform fibroblasts and round, ruff‐like cells were placed into a matrix of acidic glycosaminoglycans with delicate collagen and very few reticular fibers. The turgor of this matrix is thought to protect nerves against compression and shearing strain. Renaut bodies are readily stained with alcian blue (pH 2.5) favorably in combination with immunohistochemical markers of nerve fibers. They should be regarded as a physiological response to repeated mechanical insults and are distinct from pathological alterations. alterations. J. Morphol., 2007. © 2007 Wiley‐Liss, Inc.
Osteology and myology of the wing of the Emu (Dromaius novaehollandiae), and its bearing on the evolution of vestigial structures
Authors: Maxwell Erin E. , Larsson Hans C.E.
Published: March 2007

Emus have reduced their wing skeleton to only a single functional digit, but the myological changes associated with this reduction have never been properly described. Moreover, the intraspecific variability associated with these changes has not previously been examined, dissections having been restricted in the past to only one or two individuals. In this paper, the myology and osteology of the Emu wing is described for a sample of five female birds. The Emu showed a marked reduction in the number of muscles in the wing, even compared with other ratites. Many wing muscles showed diversity in structure, origin and insertion sites, number of heads, as well as presence–absence variation. This variability dramatically exceeds that found in flying birds. Evolutionary theory predicts that relaxed selection on vestigial organs should allow more variation to persist in the population, and corresponds to what is observed here. A large amount of fluctuating asymmetry was also detected, indicating reduced canalization of the wing during development. J. Morphol. © 2007 Wiley‐Liss, Inc.
Separation of basic and acidic compounds by capillary electrochromatography using monolithic silica capillary columns with zwitterionic stationary phase
Authors: Hu Jiwei , Xie Chuanhui , Tian Ruijun , He Zhike , Zou Hanfa
Published: March 2007

A novel monolithic silica column with zwitterionic stationary phase was prepared by in‐situ covalent attachment of phenylalanine to a 3‐glycidoxypropyltriethoxysilane‐modified silica monolith. Due to the zwitterionic nature of the resulting stationary phase, the density and sign of the net surface charge, and accordingly the direction and magnitude of electroosmotic flow in this column during capillary electrochromatography could be manipulated by adjusting the pH values of the mobile phase. CEC separations of various acidic and basic compounds were performed on the prepared column in anodic and weakly cathodic EOF modes, respectively. The peak tailing of basic compounds in CEC on a silica column could be alleviated at optimized buffer compositions. Besides the electrophoretic mechanism and weak hydrophobic interaction, weak cation‐ and anion‐exchange interactions are also involved in the separations of acids and bases, respectively, on the zwitterionic column.
Potential of solid phase microextraction and gas chromatography for quarantine‐required detection of wood packaging in shipping containers
Authors: More Nicole A. , Braggins Terry J. , Goldson Stephen L.
Published: March 2007

Solid phase microextraction (SPME) coupled with gas chromatography (GC) was used to detect terpene hydrocarbons inside shipping containers entering New Zealand. The utility of this system for the rapid detection of undeclared wood packaging for quarantine purposes was demonstrated. A portable dynamic air‐sampling device was built to house a SPME fibre and allow the air from shipping containers to be sampled. The effects of sample flow rate and sampling time were investigated and sampling conditions of 100 mL/min for 30 s were chosen to keep sampling within the linear range. A CV of less than 15% (n = 12) was obtained for all the compounds analysed under these conditions. To obtain an estimate for the limit of detection (LOD) for the terpene hydrocarbons of interest, small quantities of lime oil were placed in an empty shipping container and the air inside was analysed. LOD (S/N = 3) was estimated to be in the order of 50–100 ng/L of air using GC with flame ionisation detection (GC‐FID). Finally, the device was tested in fully laden containers and was shown to be effective for trapping terpene hydrocarbons indicative of wood packaging.
Fabrication of a poly(styrene–octadecene–divinylbenzene) monolithic column and its comparison with a poly(styrene–divinylbenzene) monolithic column for the separation of proteins
Authors: Gu Congying , Lin Li , Chen Xiaodong , Jia Jinping , Ren Jicun , Fang Nenghu
Published: March 2007

In this paper, a poly(styrene‐octadecene‐divinylbenzene) (PS‐OD‐DVB) monolithic column was prepared in one step by introducing a C18 carbon chain as monomer. N,N‐Dimethylformamide and decanol served as porogens to make a homogeneous polymerization mixture in a fused silica capillary (320 μm inner diameter). Its physical and chromatographic properties were compared with those of poly(styrene‐divinylbenzene) (PS‐DVB) monolithic column, which was also fabricated by in‐situ polymerization in a fused silica capillary with the same inner diameter. Six standard proteins were used to evaluate the columns and their potential application for the separation of human hemoglobin was also discussed. It was shown that the PS‐OD‐DVB and PS‐DVB monoliths appeared to have similar efficiency for rapid separation of six proteins within 3.5 min. The PS‐OD‐DVB monolith was found to have higher loading capacity and higher resolution for the separation of α and β chains of hemoglobin because of the introduction of C18 carbon chains, and shows great potential for the separation of bio‐macromolecules.
Development and validation of a stability‐indicating liquid chromatographic method for determination of emtricitabine and related impurities in drug substance
Authors: Seshachalam Unnam , Haribabu Bodepudi , Chandrasekhar Kottapalli B.
Published: March 2007

A novel stability‐indicating high‐performance liquid chromatographic (HPLC) method was developed and validated for assay and determination of impurities of emtricitabine in drug substance. Emtricitabine was found to be degraded under acidic, alkaline, and oxidative stress conditions and to be more labile under oxidative conditions. The drug proved to be stable to dry heat and photolytic degradation. Resolution of major and minor degradation impurities was achieved on an Intersil ODS‐3V column utilizing 10 mM sodium phosphate buffer and methanol (85:15) as mobile phase. Detection was at 280 nm. Validation studies were performed as per ICH recommended conditions. The developed method was found to be linear, accurate, specific, selective, precise, and robust.
A new procedure for separation of complex mixtures of pesticides by multidimensional planar chromatography
Authors: Tuzimski Tomasz
Published: March 2007

The objective of this communication is to report a new procedure for the separation of complex mixtures of pesticides by a combination of different modes of multidimensional planar chromatography. Complete separation of a mixture of pesticides was carried out by multidimensional planar chromatography on silica gel plates. The plates were videoscanned to show a real picture of the experimental results. Complete separation of all compounds was not possible by a single development on silica gel. The separation can be characterized as [PC×(nPC + PC + PC + PC)]. With the aid of this new procedure a complex mixture of fourteen compounds was separated on a 10×10 cm TLC plate.
Sensitive capillary electrophoretic determination of mercury species with amperometric detection at a copper electrode after cation exchange preconcentration
Authors: Kubáň Petr , Houserová Pavlína , Kubáň Pavel , Hauser Peter C. , Kubáň Vlastimil
Published: March 2007

A capillary electrophoretic method for the separation of four mercury species with amperometric detection was developed. Inorganic Hg2+, methyl‐, ethyl‐, and phenylmercury were complexed with L‐cysteine and separated in a counterelectroosmotic mode in an electrolyte solution comprised of 20 mM sodium tetraborate at pH 9.5. Amperometric detection of separated species was achieved at passivated copper electrode under electrocatalytic oxidation conditions. The four mercury species were separated in less than 8 min with LODs ranging from 170 to 450 μg/L. Cation exchange preconcentration was used to decrease the LODs down to 1.7 μg/L.
Study on the Phase Behavior of High Density Polyethylene – Ethylene Octene Copolymer Blends
Authors: Mileva Daniela , Radusch Hans‐Joachim , Betchev Christo
Published: March 2007

The processes of melting and crystallization of blends based on HDPE and EOC were investigated. DSC thermograms showed that a separate crystallization and co‐crystallization occurred in the blends studied. Avrami approach was used to analyze the kinetics of crystallization in the blends. It is shown that the Avrami exponent depends on the EOC concentration of the samples studied. The difference in the Avrami parameters for HDPE, EOC and the blends indicated that the nucleation mechanism and dimension of the spherulite growth of the blends were different from that of HDPE to some extent. The crystal growth was examined in the context of the Lauritzen‐Hoffman theory. DSC traces obtained at different cooling rates were used for analyzing the non‐isothermal crystallization. It was found that the Ozawa model was rather inapplicable for the materials studied. In contrast, the Avrami equation modified by Jeziorny can be used more efficiently to describe the non‐isothermal crystallization behavior of HDPE‐EOC blends.

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Polymer/Phenanthrene‐Derivative Host‐Guest Systems: Rheological, Optical and Thermal Properties
Authors: Hanemann Thomas , Böhm Johannes , Honnef Kirsten , Ritzhaupt‐Kleissl Eberhard , Haußelt Jürgen
Published: March 2007

Starting from commercially‐available, polymer‐based reactive resins like acrylates or unsaturated polyesters, a systematic investigation was carried out as to the influence organic dopants like phenanthrene and its derivatives have on the optical and thermal properties of the mixtures resulting from curing to the final thermoplastic polymer. The refractive index of PMMA at 633 nm can be increased, starting from 1.49 for the pure polymer, up to a value of around 1.55, and, in the case of the polyester, from 1.565 up to 1.6. The transmittance in the visible range is slightly affected at a lower dopant concentration of up to 10 wt.‐%, and remains better than 80% for a sample with a thickness of 1 mm, in the range between 500 and 800 nm. An unwanted side‐effect of larger dopant concentrations is to lower the glass transition temperature significantly.

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Effect of Surface Modification on the Synthesis of Pore‐Filling Polymeric Monoliths in Microfiltration Membranes Made from Poly(propylene) and Poly(ethylene terephthalate)
Authors: Salam Abdus , Ulbricht Mathias
Published: March 2007

The effect of pre‐modification on the interaction of macroporous substrates (membranes) with mainly micro‐ and mesoporous polymer monoliths has been studied. Bulk, porous polymer monoliths were synthesized to optimize the synthesis conditions and their pore morphology, and the data were used as benchmark for this study. Pre‐modification of the entire pore surface of PP microfiltration membranes and PET track‐etched membranes by UV‐initiated grafting with PEGMA was performed using well‐established methods, including coating with the photo‐initiator, benzophenone. Subsequently, these membranes were functionalized by filling the pores with porous polymer monoliths from MAA and EDMA and compared with membranes that had been functionalized without the pre‐modification step. The materials were characterized mainly by the degree of grafting, SEM and by the gas‐adsorption‐isotherm method. The DG values, after composite‐membrane preparation under identical conditions, were not influenced by the pre‐modification. However, it could be clearly seen from the SEM images that the pre‐modification step prevents the formation of voids at the monolith‐membrane pore interface. Larger specific surface area and pore volume values for composite membranes, prepared after pre‐modification, fully support the SEM results. Especially large differences in pore structure between the two different composite membranes were found in the mesopore range. The results of this study indicate that it is possible to prepare porous, composite membranes where the trans‐membrane transport is exclusively controlled by the pore and surface structure of a functional polymeric monolith, for example, made from a molecularly‐imprinted polymer.

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An Algorithm Based on Simple Rules for the Determination of the Architecture of Branched Polymer Molecules from the Number of Branching Points per Molecule
Authors: Majesté Jean‐Charles , Carrot Christian , Stanescu Paul‐Octavian , Mardon Coralie
Published: March 2007

A general simple algorithm is proposed to determine the average architecture of an acyclic branched polymer macromolecule from its number of branching points, whatever their functionality. The number of branching points can be derived from SEC measurements using a coupling of viscosimetric and refractometric detectors through the use of the Zimm‐Stockmayer equation. Since various isomers can be built for a given number of branching points, some basic rules are proposed in order to select the structures that are physically meaningful; the possibility of structural isomers has been also investigated and a probability of presence is assigned to each species starting from the compactness of the molecule. For each species corresponding to a given molecular weight in the sample, the average structure is then obtained from the number of branching points and the universal probability distribution of the isomers.

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The Effect of Pressure on the Microphase Separation of Diblock Copolymer Melts Studied by Dynamic Density Functional Theory Based on Equation of State
Authors: Xu Hui , Liu Honglai , Hu Ying
Published: March 2007

The effect of pressure on the microphase separation of diblock copolymer melts was investigated by dynamic density functional theory based on equation of state. The results correspond well with experiment data. With the application of high pressure, all of the phase regions corresponding to the different ordered morphologies become narrower. However, the pressure dependence of the order‐disorder transition temperature (TODT) relies on the symmetry of the diblock copolymer. In the very non‐symmetrical case when f is small, TODT decreases with increasing pressure, while in the symmetrical case when f = 0.5, TODT increases with increasing pressure. For the latter case, the increase in the total bead number of the system at the ODT is found, which is in good accordance with the experimental phenomenon that there is an increase in volume accompanying with the transition from ordered to disordered state. In contrast to the temperature, the pressure does not influence the starting time and the duration of microphase separation.

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Conformational Study of Short Peptoid Models for Future Applications as Potent Antimicrobial Compounds
Authors: Nandel Fateh Singh , Saini Avneet
Published: March 2007

Development of peptides as clinically useful drugs is limited by their poor metabolic stability and low bioavailability. Recent progresses in chemical synthesis and design have led to several strategies for producing potent mimetics. This study aims to analyze sequence/structure requirements and composition for antimicrobial peptoid designs, as use of peptoids is one of the most representative approaches to meet the goal of biomimicry. Analysis of the designs showed that for maximum activity and minimum hemolysis, the plane of the aromatic residues should be at an angle between 0 and 90 ° with respect to membranes, cationic residues need not be at the terminal position, and central positions should be uniform in NIle, NLys, and NPhe residues.

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Macromol. Theory Simul. 3/2007
Authors: Lira Alfredo López , Zolotukhin Mikhail G. , Fomina Lioudmila , Fomine Sergei
Published: March 2007

Cover: The picture shows that diprotonation of carbonyl compounds does not occur in triflic acid. The triflic acid mediated reaction of polyhydroxyalkylation of aromatic hydrocarbons involves only monoprotonated species. The reactivity of carbonyl molecules is governed by electronic effects of the groups linked directly to the carbonyl. Strong donor and strong electron withdrawing groups reduce the reactivity of carbonyl group as electrophile; in the first case the protonation leads to the formation of excessively stable cation, in the second one monoprotonation is impossible thermodynamically. Further details can be found in the article by A. L. Lira, M. G. Zolotukhin, L. Fomina, and S. Fomine* on page 227.
Solving singularly perturbed advection–reaction equations via non‐standard finite difference methods
Authors: Lubuma Jean M.‐S. , Patidar Kailash C.
Published: March 2007

We design and implement two non‐standard finite difference methods (NSFDMs) to solve singularly perturbed advection–reaction equations (SPARE). Our methods constitute a big plus to the class of those ‘rare’ fitted operator methods, which can be extended to singularly perturbed partial differential equations. Unlike the standard finite difference methods (SFDMs), the NSFDMs designed in this paper allow the time and the space step sizes to vary independently of one another and of the parameter ε in the SPARE under consideration. The NSFDMs replicate the linear stability properties of the fixed points of the continuous problem. Furthermore, these methods preserve the positivity and boundedness properties of the exact solution. Numerical simulations that confirm the theoretical results are presented. Copyright © 2007 John Wiley & Sons, Ltd.
A fourth‐order parabolic equation in two space dimensions
Authors: Liu Changchun
Published: March 2007

In this paper, we consider an initial‐boundary problem for a fourth‐order nonlinear parabolic equations. The problem as a model arises in epitaxial growth of nanoscale thin films. Based on the Lp type estimates and Schauder type estimates, we prove the global existence of classical solutions for the problem in two space dimensions. Copyright © 2007 John Wiley & Sons, Ltd.
Asymptotic waveform evaluation for scattering by inhomogeneous dielectric bodies of revolution
Authors: Kucharski Andrzej A.
Published: March 2007

In this article, an application of the asymptotic waveform evaluation technique to accelerate wideband scattering analysis by lossless dielectric objects is given. The solution is based on the volume integral equation together with the method‐of‐moments. Computational examples for so‐called bodies‐of‐revolution are given. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1028–1031, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22326
Broadband integrated DTV antenna for USB dongle application
Authors: Li Wei‐Yu , Wong Kin‐Lu , Su Saou‐Wen
Published: March 2007

A novel broadband planar antenna integrated in the USB dongle for digital television (DTV) signal reception is presented. The planar antenna is printed on a dielectric substrate and electrically connected to the system ground plane of the USB dongle. When in operation, the planar antenna is swung upward to be perpendicular to the system ground plane and can provide a wide operating bandwidth (2.5:1 VSWR) of larger than 50% centered at about 630 MHz, allowing it to cover the DTV signal reception in the 470–806‐MHz band. While not in operation, the planar antenna can be swung downward and attached onto the housing of the USB dongle, keeping the aesthetic appearance of the device. Detailed design considerations of the proposed antenna are described, and obtained experimental and simulation results are presented and discussed. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1018–1021, 2007; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.22329
A novel filter based on zeroth‐order resonance by means of CRLH transmission line
Authors: Sun Yuanyuan , Zhang Yewen , Liu Fuqiang , He Li , Li Hongqiang , Chen Hong
Published: March 2007

A novel band‐pass filter based on zeroth‐order resonance is presented in this article. The filter offers a 68% size reduction compared to the traditional coupled‐line filter, while keeping the same performance. The experimental results of the filter are in good agreement with the Advanced Design System simulation results. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1015–1018, 2007; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.22332
Robust GMRES recursive method for fast finite element analysis of 3D electromagnetic problems
Authors: Rui P. L. , Chen R. S.
Published: March 2007

A robust generalized minimal residual recursive (GMRESR) iterative method is proposed to solve a large system of linear equations resulting from the use of an un‐gauged vector‐potential formulation of finite element method (FEM). This method involves an outer generalized conjugate residual (GCR) method and an inner generalized minimal residual (GMRES) method, where the inner GMRES acts as a variable preconditioning for the outer GCR. The efficient implementation of symmetric successive overrelaxation (SSOR) preconditioned GMRESR (SSOR‐GMRESR) algorithm is described in details for complex coefficient matrix equation. On several three‐dimensional electromagnetic problems, the resulting SSOR‐GMRESR approach converges in CPU time, which is 14.2–71.3 times shorter with respect to conventional conjugate gradient (CG) approach. By comparison with other popularly preconditioned CG methods, the results demonstrate that SSOR‐GMRESR is especially effective and robust when the A‐V formulation of FEM is applied to solve large‐scale time harmonic electromagnetic field problems. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1010–1015, 2007; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.22333
Electromagnetic scattering from high order inhomogeneous impedance cylinder of arbitrary shape by using physical optics
Authors: Tezel Necmi Serkan
Published: March 2007

In this study, physical optics (PO) method have been applied to electromagnetic scattering problem related to high order inhomogeneous impedance cylinder of arbitrary shape. In the solution, induced electric and magnetic currents on the illuminated region of surface are expressed by means of incident field and high order inhomogeneous impedance boundary condition then scattered field is calculated using Huygens type Green's formula. Obtained scattering width results are compared with those obtained by other analytical and numeric methods and good agreements are observed especially monostatic case. Because of the fact that PO method does not need matrix inversion, which requires high CPU time, PO method also significantly reduces computer calculation time according the other methods. In this study, TM case is considered, but similar procedure can be easily applied to TE case and even also three‐dimensional inhomogeneous impedance objects using dyadic Green's functions as well. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1031–1036, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22339
Ultra wideband printed monopole antenna
Authors: Thomas K. George , Lenin N.
Published: March 2007

An ultra wideband printed planar elliptical monopole is reported. The antenna has a simple printed structure, mounted perpendicular to a small metallic ground plane. The proposed antenna can be used for multiband operation, with omnidirectional radiation pattern in azimuth plane. The antenna operates over an extremely wide impedance bandwidth of more than 25:1, determined by 10 dB return loss and covers almost all present day wireless communication systems: Advanced mobile phone system, global system for mobile communication, digital communication system, universal mobile telecommunication system, and broadband wireless metropolitan area network system for operation in the 2–11 GHz band. This article presents the design, analysis, and experimental results for the proposed antenna. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1082–1085, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22343
Novel power divider with fixed strip width using offset double‐sided parallel‐strip lines
Authors: Chen Jian‐Xin , Chin Ching‐Hong K. , Xue Quan
Published: March 2007

A novel power divider with fixed strip width using offset double‐sided parallel‐strip lines (DSPSL) is proposed. The offset double‐sided parallel‐strip lines allows an additional design freedom, i.e., offset distance between the top and bottom strips of the offset double‐sided parallel‐strip lines for characteristic impedance besides the strip width. This can reduce the discontinuities effectively resulting from the change of the strip width and improve the power‐handling capability of the proposed power divider. The simulated and measured results are presented and show good agreement. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1109–1111, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22346
Coupled‐mode analysis of nonlinear fiber couplers with different core parameters
Authors: Liu Min
Published: March 2007

A nonlinear two‐core fiber coupler with unequal cores (phase‐mismatched) is analyzed by using coupled‐mode theory. Based on the solutions of the coupled‐mode equations, it is demonstrated that even though there is a difference in core diameter, the unequal‐core fiber coupler (phase‐mismatched) can function as a twin‐core fiber coupler (phase‐matched) by increasing the refractive index of the small core. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49:1051–1053, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22350
Design of bandstop filters using discrete‐time notch filter, two‐section stub, and frequency‐scaling method
Authors: Hsue Ching‐Wen , Chen Yen‐Jen , Tsai Yi‐Hsien
Published: March 2007

A new method for the design of a bandstop filter is presented. The two‐section open stub is employed to emulate a notch filter in the discrete‐time domain. A cascade connection of two‐section open stubs with proper frequency scaling serves to represent a bandstop filter of wider stopband bandwidth. Experimental results are presented to illustrate the validity of this design method. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1098–1101, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22356
A simple design cylindrical dielectric resonator antenna with wide aperture‐coupled for broadband applications
Authors: Huang Tsung‐Hui , Chen Han‐Jan , Chen Tung‐Ming , Chen Lih‐Shan , Liu Chien‐Chih , Hung Chen‐I , Wang Yeong‐Her , Houng Mau‐Phon
Published: March 2007

In this paper, a simple design cylindrical dielectric resonator antenna (CDRA) with wide aperture‐coupled for broadband applications has been proposed. For improving impedance matching, microstrip feed‐line was designed as a fork‐like to obtain two resonant modes excitation and lead to a wider impedance bandwidth. Experimental results indicate that the measured bandwidth is 10.6% (S11 < −10 dB) with broadside radiation pattern. Additionally, the proposed antenna gain is near 7.9 dBi. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49:1064–1067, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22359
Perfectly matched layer for two‐dimensional unconditionally stable FDTD method based on approximate Crank‐Nicolson scheme
Authors: Lin Hai , Ding Ping‐Ping , Wang Gaofeng
Published: March 2007

A perfectly matched layer (PML) is constructed for two‐dimensional (2D) unconditionally stable (US) FDTD method based on an approximate Crank‐Nicolson scheme. This novel PML preserves unconditional stability of the 2D US‐FDTD method and has very good absorbing performance. Numerical results are included to illustrate effectiveness and performance of this new PML. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1178–1182, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22364
LTCC bandpass filter using 3D coupled helical inductors
Authors: Choi SeungChul , Youm JungEun , Heo Keun , Lim JuHwan , Park ChulSoon , Hwang SungWoo
Published: March 2007

A new low‐temperature co‐fired ceramic (LTCC) bandpass filter using three‐dimensionally coupled helical inductors is presented. The resonator is a via‐connected multilayer helical inductor and the filter uses mixed coupling between face‐to‐face inductors. The fabricated filter exhibits the center frequency of 5.8 GHz, 3‐dB bandwidth of 800 MHz, and the insertion loss of 1.9 dB. The size of the active region is 1.7 × 2.3 × 0.8 mm3. The measured results are consistent with the three‐dimensional electromagnetic simulation and the equivalent circuit modeling. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1146–1147, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22366
Design of a low‐profile modified U‐slot microstrip antenna using PSO based on IE3D
Authors: Liu X. F. , Jiao Y. C. , Zhang F. S. , Chen Y. B.
Published: March 2007

In this article, a novel particle swarm optimization method based on IE3D is used to design a low‐profile modified U‐slot microstrip antenna. The antenna is printed on a substrate thickness of 0.008λ. Details of the particle swarm optimization method based on IE3D are presented. Experimental results including return loss and far field patterns of the antenna are given. The obtained antenna bandwidth (S11 = −10 dB) can be as large as 1.85 times that of a corresponding unslotted rectangular microstrip antenna at 2.4 GHz. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1111–1114, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22369
All‐fiber multipoint VISAR
Authors: Hong Guang‐Wei , Jia Bo
Published: March 2007

A novel all‐fiber multipoint velocity interferometer system for any reflectors (VISAR) is developed and demonstrated. The setup employs single‐mode fibers and fiber couplers to create more probing ports based on the all‐fiber VISAR. A time division multiplexing scheme is implemented to align the interfering signals of different points in time sequence. A prototype two‐point all‐fiber VISAR is established and used to measure velocities on the same specimen impacted by the split Hopkinson pressure bar. A preliminary experiment results show good matches with the expected theoretical performance. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1199–1201, 2007; Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.10 02/mop.22370
Coherent combining of Q‐switched fiber lasers based on a fiber grating ring mirror
Authors: Dai Wei , Wengang Guo , Hongjie Wang , Fuyun Lu
Published: March 2007

A coherent combining of two Q‐switched fiber lasers based on a multiarm resonator of interferometric configuration is demonstrated. The lasers share a same fiber grating ring mirror as a Q‐switch and generate a stable pulse series. Under a 23‐KHz pulse repetition, a 10‐mW average output power is obtained and the pulse peak power is 46 mW. The combining efficiency of the two fiber lasers reaches 90%. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49:1196–1199, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22371