bluuebunny/crossref_metadata_2025 huggingface dataset:
Heuristic algorithms for routing yard‐side equipment for minimizing loading times in container terminals
Authors: Kim Ki Young , Kim Kap Hwan
Published: July 2003

This paper discusses a method of routing yard‐side equipment during loading operations in container terminals. Both the route of yard‐side equipment (such as transfer cranes or straddle carriers) and the number of containers picked up at each yard‐bay is determined simultaneously. The objective of the problem in this paper is to minimize the total container‐handling time in a yard. The size of the search space can be greatly reduced by utilizing inherent properties of the optimal solution. An encoding method is introduced to represent solutions in the search space. A genetic algorithm and a beam search algorithm are suggested to solve the above problem. Numerical experiments have been conducted to compare the performances of the proposed heuristic algorithms against each other and against that of the optimal solution. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 498–514, 2003
Algorithms for source‐to‐all maximum cost‐to‐time ratio problem in acyclic networks
Authors: Makri Alexandra , Klabjan Diego
Published: July 2003

The source‐to‐all maximum cost‐to‐time ratio problem is the problem of finding the maximum cost‐to‐time ratio path from a source node to every other node. The motivation comes from an application in large‐scale linear programming. We present three algorithms for solving the problem. We give proofs of correctness and we analyze the running times. One of the algorithms is polynomial and the remaining two are pseudopolynomial. We present extensive computational results on several networks. © 2003 Wiley Periodicals, Inc.
A general construction for nonblocking crosstalk‐free photonic switching networks
Authors: Hwang Frank K. , Lin Wen‐Dar
Published: July 2003

The graph representation G(M) of a multistage switching network M is well known. Lea IEEE Trans Commun 38 (1990), 529–538 observed that link‐disjoint paths in M correspond to node‐disjoint paths in G(M). He proposed G(M) as a network by treating nodes as crossbars to transfer the node‐disjoint property to the crosstalk‐free property essential for photonic networks using directional couplers as components. However, such a network has its peculiarities and is not commonly used. In this paper, we will show how to take advantage of this correspondence to construct nonblocking crosstalk‐free networks using the vertical stacking method. Our construction simplifies the proofs of many existing results, as well as establishing some new results. © 2003 Wiley Periodicals, Inc.
An exact algorithm for the Traveling Salesman Problem with Deliveries and Collections
Authors: Baldacci R. , Hadjiconstantinou E. , Mingozzi A.
Published: July 2003

In this paper, we describe a new integer programming formulation for the Traveling Salesman Problem with mixed Deliveries and Collections (TSPDC) based on a two‐commodity network flow approach. We present new lower bounds that are derived from the linear relaxation of the new formulation by adding valid inequalities, in a cutting‐plane fashion. The resulting lower bounds are embedded in a branch‐and‐cut algorithm for the optimal solution of the TSPDC. Computational results on different classes of test problems taken from the literature indicate the effectiveness of the proposed method. © 2003 Wiley Periodicals, Inc.
The spectra of wrapped butterfly digraphs
Authors: Comellas Francesc , Fiol Miquel Angel , Gimbert Joan , Mitjana Margarida
Published: July 2003

The knowledge of the spectrum of a (di)graph is relevant for estimating some of its structural properties, which provide information on the topological and communication properties of the corresponding networks. Among these properties, we have, for instance, edge‐expansion and node‐expansion, bisection width, diameter, maximum cut, connectivity, and partitions. In this paper, we determine the complete spectra (eigenvalues and multiplicities) of wrapped butterfly digraphs. © 2003 Wiley Periodicals, Inc.
CB1 cannabinoid receptor activation inhibits a neural correlate of song recognition in an auditory/perceptual region of the zebra finch telencephalon
Authors: Whitney Osceola , Soderstrom Ken , Johnson Frank
Published: July 2003

A notable consequence of CB1 cannabinoid receptor activation in vertebrates is an impairment of cognitive function related to learning and short‐term memory. The mechanisms of this impairment remain unclear, but one possibility is that cannabinoids influence encoding of stimuli at sensory and/or perceptual levels. Here, by treating zebra finches with the cannabinoid agonist WIN55212‐2 and then measuring expression of the transcription factor zenk following presentation of novel zebra finch song, we show that cannabinoid receptor activation differentially influences zenk expression in sensory versus perceptual regions of the songbird auditory telencephalon. That is, WIN55212‐2 dose‐dependently inhibited zenk expression in a region for auditory perception (NCM, the caudomedial neostriatum), but had no effect on zenk expression in the primary auditory area, the Field L complex. The inhibitory effects of WIN55212‐2 on zenk expression in NCM were reversed by coadministration of the CB1‐selective antagonist SR141716A. Moreover, we found that the habituation of the NCM zenk response to repeated presentation of the same song, a well‐established neural correlate of song recognition, was blocked when birds were treated with WIN55212‐2 during habituation trials. Our data suggest that activation of CB1 cannabinoid receptors can selectively influence perceptual and mnemonic aspects of auditory experience. © 2003 Wiley Periodicals, Inc. J Neurobiol 56: 266–274, 2003
Synaptic plasticity and functionality at the cone terminal of the developing zebrafish retina
Authors: Biehlmaier Oliver , Neuhauss Stephan C.F. , Kohler Konrad
Published: July 2003

Previous studies have analyzed photoreceptor development, some inner retina cell types, and specific neurotransmitters in the zebrafish retina. However, only minor attention has been paid to the morphology of the synaptic connection between photoreceptors and second order neurons even though it represents the transition from the light sensitive receptor to the neuronal network of the visual system. Here, we describe the appearance and differentiation of pre‐ and postsynaptic elements at cone synapses in the developing zebrafish retina together with the maturation of the directly connecting second order neurons and a dopaminergic third order feedback‐neuron from the inner retina. Zebrafish larvae were examined at developmental stages from 2 to 7dpf (days postfertilization) and in the adult. Synaptic maturation at the photoreceptor terminals was examined with antibodies against synapse associated proteins. The appearance of synaptic plasticity at the so‐called spinule‐type synapses between cones and horizontal cells was assessed by electron microscopy, and the maturation of photoreceptor downstream connection was identified by immunocytochemistry for GluR4 (AMPA‐type glutamate receptor subunit), protein kinase β1 (mixed rod‐cone bipolar cells), and tyrosine hydroxylase (dopaminergic interplexiform cells). We found that developing zebrafish retinas possess first synaptic structures at the cone terminal as early as 3.5dpf. Morphological maturation of these synapses at 3.5–4dpf, together with the presence of synapse associated proteins at 2.5dpf and the maturation of second order neurons by 5dpf, indicate functional synaptic connectivity and plasticity between the cones and their second order neurons already at 5dpf. However, the mere number of spinules and ribbons at 7dpf still remains below the adult values, indicating that synaptic functionality of the zebrafish retina is not entirely completed at this stage of development. © 2003 Wiley Periodicals, Inc. J Neurobiol 56: 222–236, 2003
Accuracy in the outcomes and assessment information set (OASIS): Results of a video simulation
Authors: Madigan Elizabeth A. , Tullai‐McGuinness Susan , Fortinsky Richard H.
Published: July 2003

There is little information regarding the accuracy of the Outcomes and Assessment Information Set (OASIS), the patient assessment tool mandated for use in Medicare‐funded home health care. The purposes of this study were to evaluate the accuracy of OASIS completion by home health nurses and rehabilitation therapists, to compare responses of nurses and therapists, and to determine whether dispersion of answers would affect the home health resource group (HHRG) to which patients were assigned for Medicare home health care payments to agencies. Using a video simulation of admission and discharge visits, 436 clinicians from 29 Ohio home health care agencies scored selected OASIS items. Although the majority of the items were rated accurately, discrepancies were found between clinician responses and the “correct” answer on several items. Nurses and therapists provided similar ratings on most items studied, but for most cases in which discrepancies were found, nurses were more likely to agree with the “correct” answer. Discrepancies most often led to patients being assigned to lower‐payment HHRGs. Continued monitoring of OASIS data collection accuracy is recommended to maximize the value of the OASIS instrument in home health care research, practice, and policy. © 2003 Wiley Periodicals, Inc. Res Nurs Health 26:273–283, 2003
Reversal theory states and cigarette availability predict lapses during smoking cessation among adolescents
Authors: Burris Rebecca F. , O'Connell Kathleen A.
Published: July 2003

Although 67% of adolescent smokers say they want to quit, only 7% are able to do so. The purpose of this study was to use metamotivational states as described in reversal theory to predict whether adolescents who are trying to quit smoking will lapse (smoke a cigarette) or will resist smoking in highly tempting situations. Reversal theory holds that individuals switch between telic (serious‐minded) and paratelic (playful) metamotivational states. Questionnaires and semistructured interviews were administered to 62 adolescents ages 14–19 who had participated in a smoking cessation program. Interviews were coded according to the Metamotivational State Interview and Coding Schedule, and the resulting data were analyzed using logistic regression analysis. Adolescents in the paratelic metamotivational state (OR = 15.34; 95% CI: 5.3, 43.6) or with cigarettes readily available (OR = 4.6; 95% CI: 1.6, 13.2) were more likely to lapse than were adolescents in the telic state or who required effort to obtain cigarettes. The variables telic/paratelic state and cigarette availability accurately predicted the outcome of highly tempting situations 80% of the time. Using reversal theory constructs to develop state‐specific strategies shows promise as an additional tool for those in this age group coping with the temptation to smoke. © 2003 Wiley Periodicals, Inc. Res Nurs Health 26:263–272, 2003
Preparation and characterization of microcapsulated red phosphorus and its flame‐retardant mechanism in halogen‐free flame retardant polyolefins
Authors: Wu Qiang , Lü Jianping , Qu Baojun
Published: July 2003

Microcapsulated red phosphorus (MRP), with a melamine–formaldehyde resin coating layer, was prepared by two‐step coating processes. The physical and chemical properties of MRP were characterized by Fourier‐transform infrared spectroscopy (FTIR), X‐ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) and other measurements. The flame retardant action and mechanism of MRP in the halogen‐free flame retardant (HFFR) polyolefins (PO) blends have been studied using cone calorimeter, limiting oxygen index (LOI), thermogravimetric analysis (TGA) and dynamic FTIR spectroscopy. The results show that the MRP, which is coated with melamine–formaldehyde resin, has a higher ignition point, a considerably lower amount of phosphine evolution and of water absorption compared with red phosphorus (RP) itself. The data observed by cone calorimeter, LOI and TGA measurements from the PO/HFFR blends demonstrated that the MRP can decrease the heat release rate and effective heat of combustion, and increase the thermostability and LOI values of PO materials. The dynamic FTIR results revealed the flame‐retardant mechanism that RP can promote the formation of charred layers with the P–O and P–C complexes in the condensed phase during burning of polymer materials. Copyright © 2003 Society of Chemical Industry
Synthesis and antitumour activity of medium molecular weight phthalimide polymers of camptothecin
Authors: Lee Neung‐Ju , Ju Sung‐Suk , Cho Won‐Jei , Kim Seon‐Hee , Kang Kyung‐Tae , Brady Thomas , Theodorakis Emmanuel A
Published: July 2003

Attachment of anticancer agents to polymers has been demonstrated to improve their therapeutic profiles. A new monomer containing camptothecin, 5‐norbonene‐endo‐2,3‐dicarboxylimidoundecanoyl‐camptothecin (NDUCPT) and its homopolymer and copolymer with acrylic acid (AA) were synthesized and spectroscopically characterized. The NDUCPT content in poly(NDUCPT‐co‐AA) obtained by elemental analysis was 51%. The average molecular weights of the polymers determined by gel permeation chromatography were as follows: Mn = 12 100, Mw = 23 400 g mol−1, Mw/Mn = 1.93 for poly(NDUCPT), Mn = 15 400, Mw = 28 300 g mol−1, Mw/Mn = 1.83 for poly(NDUCPT‐co‐AA). The IC50 value of NDUCPT and its polymers against U937 cancer cells was larger than that of CPT. The in vivo antitumour activity of all polymers in Balb/C mice bearing the sarcoma 180 tumour cell line was greater than that of CPT at a dose of 100 mg kg−1. Copyright © 2003 Society of Chemical Industry
Synthesis and characterization of functionalized vinyl copolymers. Electronegativity and comonomer reactivity in radical copolymerization
Authors: Gatica Nicolás , Fernández Natalí , Opazo Alejandra , Alegría Sergio , Gargallo Ligia , Radic Deodato
Published: July 2003

Vinylsilane monomers (vinyltrimethoxysilane (VTMOS) and vinyltriethoxysilane (VTEOS)), methyl methacrylate (MMA), tert‐butyl acrylate (tBA) and N‐vinyl‐2‐pyrrolidone (VP) were used in the synthesis of functionalized vinyl copolymers. By using these monomers, VTMOS‐co‐MMA, tBA‐co‐VP and VTEOS‐co‐VP, with various compositions, were synthesized. The copolymers were characterized by viscometry, 1H‐NMR, FTIR and elemental analysis. The monomer reactivity ratios were estimated by the Fineman–Ross and Kelen–Tüdõs linear procedures. These parameters were also estimated by using a computer program based on a non‐linear minimization procedure known as Reactivity Ratios Error in Variables Model. Random copolymers and others containing blocks of one of the monomer units were obtained, depending on the chemical nature of the comonomers. The estimated comonomer sequence and distribution are discussed in terms of structural properties of the monomers such as molecular volume of the side groups, electronegativity of the substituents and steric hindrance. Analysis by comparison with other copolymers with analogous structures was also performed. Copyright © 2003 Society of Chemical Industry
A study on polyurethane/acrylate crosslinked gel polymer electrolytes
Authors: Xiaobin Huang , Tianbin Ren , Xian Zhao , Xiaozhen Tang
Published: July 2003

2,4‐Toluene diisocyanate, poly(propylene glycol), poly(ethylene glycol) (PEG) and 2‐hydroxyethyl methacrylate were used to synthesize PEG–UA (urethane acrylate) monomer. The crosslinked polymer and gel polymer electrolytes were prepared in dioxane by free radical polymerization. The swelling behaviour, thermal degradation properties, morphology and ionic conductivity of the gel polymer electrolytes were investigated. With decrease in the proportion of dioxane used, the synthesized polymer's network density increased, its affinity with a solution of 1 M LiClO4 in propylene carbonate (PC) decreased, and more microgel which diffused in the network. At the same time, the conductivity increased and reached 4 × 10−4 S cm−1 at 25 °C. Copyright © 2003 Society of Chemical Industry
Synthesis and characteristics of radiation‐grafted membranes for fuel cell electrolytes
Authors: Liang Guo‐zheng , Lu Ting‐li , Ma Xiao‐yan , Yan Hong‐xia , Gong Zhao‐he
Published: July 2003

Proton exchange membranes were prepared by simultaneous radiation grafting of styrene onto polytetrafluoroethylene (PTFE) films at room temperature and subsequent sulfonation by chlorosulfonic acid. A series of grafted films with degree of grafting ranging from 0.947% to 35.4% were obtained. The effect of styrene concentration on the grafting yield was investigated and the maximum value was obtained at a monomer concentration of 70‐vol%. The structure of PTFE‐graft‐polystyrene sulfonic acid membranes was studied by infrared spectroscopy. The membrane properties, such as water uptake, ion exchange capacity, swelling performance and ionic resistance, were studied as functions of the degree of grafting. The thermal and chemical stability of the sulfonic acid membranes was also investigated. The membrane properties were found to depend on the degree of grafting and the amorphous character of the membrane structure, and the better membrane properties were obtained at a degree of grafting in the range 12–21%. Copyright © 2003 Society of Chemical Industry
Synthesis and characterization of poly(butylene terephthalate)‐co‐poly(butylene succinate)‐block‐poly(ethylene glycol) segmented block copolymers
Authors: Zhang Yong , Feng Zeng‐Guo , Zhang Ai‐Ying
Published: July 2003

Poly(butylene terephthalate)‐co‐poly(butylene succinate)‐block‐poly(ethylene glycol) segmented random copolymers, with poly(butylene succinate) (PBS) molar fraction (MPBS) varying from 10 to 60 %, were synthesized through a melt polycondensation process and characterized by means of GPC, NMR, DSC and mechanical testing. The number‐average relative molecular mass of the copolymers was higher than 4 × 104 g mol−1 with polydispersity below 1.9. Sequence distribution analysis on the two types of hard segments by means of 1H NMR revealed that the number‐average sequence length of PBT decreased from 2.80 to 1.23, while that of PBS increased from 1.27 to 4.76 with increasing MPBS. The random distribution of hard segments was also justified because of the degree of randomness around 1.0. Micro‐phase separation structure was verified for the appearance of two glass transition temperatures and two melting points, respectively, in DSC thermograms of most samples. The crystallinity of hard segments changed with the crystallizability controlled by the average sequence length and reached the minimum value at an MPBS of about 50–60 mol%. The results can also be ascribed to the co‐crystallization between two structurally analogous hard segments. Mechanical testing results demonstrated that incorporating a certain amount of PBS moieties (less than 30 mol%), at the expense of a minute depression of the elastic modulus, that higher relative elongation and more flexibility of polymer chain could be expected. Maximum equilibrium water absorption and faster degradation rates were observed on samples with higher MPBS values and lower crystallinity of hard segments were better hydrophilicity of the polymer chain, through in vitro degradation experiments. Copyright © 2003 Society of Chemical Industry
Role of short polyisoprene chains in storage hardening of natural rubber
Authors: Ngolemasango F , Ehabe E , Aymard C , Sainte‐Beuve J , Nkouonkam B , Bonfils F
Published: July 2003

Drying of natural rubber (NR) crumb (grade TSR10) requires high temperatures (100–120 °C). In order to determine the changes in bulk viscosity during the drying process, ageing kinetics at 120 °C were studied on model NR samples. During the process, changes in Mooney viscosity and weight‐average molar mass (MW) were monitored. Rubber from clones GT 1 and PR 107, with a bimodal inherent molar mass distribution (MMD0), was degraded in a two‐phase process. During the first phase, Mooney viscosity and MW increased, undoubtedly owing to a predominance of storage hardening over chain scissions [0 < t (min) <120]. During the second phase, chain scissions predominated (t > 120 min) and Mooney viscosity and MW decreased. For rubber samples from clone PB 217, with a unimodal MMD0, no or reduced storage hardening was observed throughout the ageing process. These results showed that the key parameter involved in storage hardening seems to be the quantity of short polyisoprene chains and probably the nature of the chain ends. Copyright © 2003 Society of Chemical Industry
Model experiments for a molecular understanding of polymer crystallization
Authors: Reiter Günter
Published: July 2003

Time‐resolved real‐space observations of morphology and pattern formation resulting from crystallization of ultrathin films of low‐molecular‐weight poly(ethylene oxide) (PEO) or diblock copolymers containing PEO shed light on the mechanisms of how polymer crystals are formed. We used simple but restricted geometries like thin films of controlled thickness or confinement resulting from block copolymer mesotructures. Under such conditions, we were able to relate the observed morphology and its temporal evolution directly to molecular processes and the kinetics of crystal growth. We demonstrate that changes in the morphology with time are due to different thermal histories and are the consequence of the mestable nature of polymer crystals. Information about the nucleation process was obtained by examining crystal formation in 12‐nm small spherical cells of a block copolymer mesostructure. We discuss the advantages of thin‐film studies for a better understanding of polymer crystallization. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1869–1877, 2003
Biodegradable electrospun mat: Novel block copolymer of poly (p‐dioxanone‐co‐L‐lactide)‐block‐poly(ethylene glycol)
Authors: Bhattarai Narayan , Cha Dong Il , Bhattarai Shanta Raj , Khil Myung Seob , Kim Hak Yong
Published: July 2003

Ultrafine fibers of a laboratory‐synthesized new biodegradable poly(p‐dioxanone‐co‐L‐lactide)‐block‐poly(ethylene glycol) copolymer were electrospun from solution and collected as a nonwoven mat. The structure and morphology of the electrospun membrane were investigated by scanning electron microscopy, differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD), and a mercury porosimeter. Solutions of the copolymer, ranging in the lactide fraction from 60 to 80 mol % in copolymer composition, were readily electrospun at room temperature from solutions up to 20 wt % in methylene chloride. We demonstrate the ability to control the fiber diameter of the copolymer as a function of solution concentration with dimethylformamide as a cosolvent. DSC and WAXD results showed the relatively poor crystallinity of the electrospun copolymer fiber. Electrospun copolymer membrane was applied for the hydrolytic degradation in phosphate buffer solution (pH = 7.5) at 37 °C. Preliminary results of the hydrolytic degradation demonstrated the degradation rate of the electrospun membrane was slower than that of the corresponding copolymers of cast film. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1955–1964, 2003
Nanostructure evolution in a poly(ether ester) elastomer during drawing and the displacement of hard domains from lamellae
Authors: Stribeck Norbert , Funari Sérgio S.
Published: July 2003

A poly(ether ester) thermoplastic elastomer with a soft block content of 50 wt % has been studied with synchrotron small‐angle X‐ray scattering (SAXS) during strain/relaxation cycles. The rigid nodes of the elastic network are not the hard domains themselves but instead are ordered three‐dimensional assemblies of several hard domains. At a critical elongation, single hard domains are disrupted and dislocated from these assemblies in a peculiar manner. In the ultimate structure, remaining pairs of hard domains form (semi)elastic nodes. The complex two‐dimensional SAXS patterns indicate stacks from tilted lamellae that are destroyed when the sample is strained to double its initial length. With multidimensional chord distribution function analysis, the complex nanostructure and its evolution in the draw experiment have been analyzed. The fundamental hard domains are not lamellae but cylinders (5 nm × 8 nm) arranged on a lattice at cylindrical coordinates (r12, r3), which are given by the intersections of r3(r12) = ±1.5r12 ± 13nmn, n being a natural number. A semielastic component is made from hard domains forming other lamellar assemblies, which are characterized by n = 3/2. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1947–1954, 2003
Phenol‐urea‐formaldehyde cocondensed resol resins: Their synthesis, curing kinetics, and network properties
Authors: He Guangbo , Riedl Bernard
Published: July 2003

Several phenol‐urea‐formaldehyde (PUF) cocondensed resol resins were synthesized by different procedures. The curing kinetics and network properties of these PUF resins were examined by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). A kinetic study indicated that the activation energy values of PUF resins are generally higher than those of phenol‐formaldehyde (PF) resins during curing processes, but the curing rates of PUF resins are faster than those of PF resins. The pH values of PUF systems have a significant influence on the rate constants, although they affect the activation energy very slightly. Moreover, the dependence of activation energy on the conversion showed that there are more individual reactions with different activation energies occurring during the curing processes in PUF resins than in PF resins. The decomposition of methylene ether bridges to form methylene bridges probably occurs at high temperature in PUF resins. DMTA data indicated that the network rigidity of PUF resins is slightly lower than that of PF resin. The gel point and Ttan δ2 transition measured by DMTA were consistent with the kinetic results obtained from the DSC data, but they were also related to the physical and mechanical properties of the network, especially with regard to the Ttan δ2 transition. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1929–1938, 2003
Mean‐field and fluctuation correction analyses for a diblock copolymer melt exhibiting an immiscibility loop
Authors: Cho Junhan , Kwon Yong K.
Published: July 2003

A study on a diblock copolymer melt that can form certain specific interactions between dissimilar monomers is performed first with a mean‐field approach and then with a fluctuation correction approach. Flory's interaction parameter χ possesses both enthalpic and entropic contributions because of the specific interactions. It is found that not only a lower critical ordering transition but also an immiscibility loop with an upper critical ordering transition can be developed in the copolymer by the presence of the specific interactions and the entropic component in χ. The mean‐field loop phase diagram is shown to feature a typical sequence of microphase transitions upon both heating and cooling with two continuous transition points at a symmetric composition. It is revealed that the fluctuation effects remove both continuous transition points to significantly shrink the loop. The pressure effects on the phase behavior of the copolymer are also discussed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1889–1896, 2003
Carpetlike dense‐layer formation in a polyelectrolyte brush at the air/water interface
Authors: Mouri Emiko , Matsumoto Kozo , Matsuoka Hideki
Published: July 2003

A carpetlike dense‐layer formation between a hydrophobic layer and a polyelectrolyte brush layer has been found in the monolayers of an ionic amphiphilic diblock copolymer, poly(1,1‐diethylsilacyclobutane)m‐block‐poly(methacrylic acid)n, on a water surface by an X‐ray reflectivity technique. By detailed analysis, we have found that the hydrophilic layer under the water is not a simple layer but is divided into two layers, that is, a carpetlike dense methacrylic acid (MAA) layer near the hydrophobic layer and a polyelectrolyte brush layer. We have also confirmed that a well‐established polyelectrolyte brush is formed only for them:n= 43:81 polymer monolayer: Form:n= 40:10 andm:n= 45:60 polymer monolayers, only a dense MAA layer is formed. This dense‐layer formation should be the origin of the interesting hydrophobic‐layer thickness variation previously reported; The hydrophobic‐layer thickness takes a minimum as a function of the hydrophilic chain length at any surface pressure studied. An overview of the data for three samples with different chain lengths (m:n= 40:10, 45:60, or 43:81) has shown that the thickness of this dense layer is 10–20 Å and is independent of the surface pressure and polymerization degree of poly(methacrylic acid) (PMAA) in the range studied. This dense‐layer formation is explained by the reasonable speculation that contact with PMAA is thermodynamically more stable than direct contact with water for the diethylsilacyclobutane (Et2SB) layer on water. In this sense, the dense layer acts like a carpet for the hydrophobic Et2SB layer, and a 10–20‐Å thickness could be a critical value for the carpet. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1921–1928, 2003
Effects of polymeric dispersants and surfactants on the dispersing stability and high‐speed‐jetting properties of aqueous‐pigment‐based ink‐jet inks
Authors: Chang Chi‐Jung , Chang Shinn‐Jen , Tsou Susan , Chen Shou‐I , Wu Feng‐Mei , Hsu Mei‐Wen
Published: July 2003

Good jetting performance and pigment‐dispersing stability are necessary for pigment‐based ink‐jet inks. This study investigates how the chemical structures of the polymeric dispersants affect the pigment‐dispersing stability and jetting performance of ink‐jet inks. A series of polymeric dispersants containing styrene (hydrophobic unit) and acrylic acid (hydrophilic unit) with different ratios have been synthesized and used to disperse different pigments. Because 3000–12,000 ink drops can be expelled from the nozzle of a thermal bubble‐type ink‐jet printer within 1 s, the jetting behavior is related to the rheology variation of a dilute solution under a high shear. An in situ drop formation system has been used to study the high‐shear‐rate rheology (dynamic surface tension and dynamic viscosity) of a solution with a viscosity lower than 3 cps, which no commercial rheometer can measure. Excellent ink‐jet inks can only be produced by the combination of pigments, dispersants, and surfactants with appropriate hydrophilicity. Moreover, the correlation of the pigment surface properties, the chemical structures of the polymeric dispersants, and ink formulation is discussed. The effects of the surfactants and firing conditions on the jetting behavior of the ink‐jet ink are also examined. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1909–1920, 2003
Impact of average free‐volume element size on transport in stereoisomers of polynorbornene. II. Impact of temperature on solubility
Authors: Wilks Broderick R. , Rezac Mary E.
Published: July 2003

This article evaluates the influence of temperature on the sorption of gases in two isomers of polynorbornene. The subject polymers were stereoisomers with nearly identical bulk density and total free volume. Because of differences in the mobility of the polymer backbone, the isomers packed differently resulting in differences in the average free‐volume element size within the matrix. The influence of these differences on free‐volume element size was characterized by the heat of sorption of gases in the matrix. The most pronounced differences were observed in the isosteric heats of sorption of condensable carbon dioxide and methane in the polymer isomers. This analysis suggests that the relative space available for sorption into free‐volume elements is higher in the methyl II isomer relative to methyl III. These conclusions support the physical characterizations reported in Part I of this series suggesting that the methyl II isomer has larger average free‐volume elements but fewer of them than the methyl III isomer. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1939–1946, 2003
Preparation and characterization of some unusually transparent poly(dimethylsiloxane) nanocomposites
Authors: Rajan Guru S. , Sur Gil S. , Mark James E. , Schaefer Dale W. , Beaucage Gregory
Published: July 2003

A technique was developed for preparing poly(dimethylsiloxane) nanocomposites having unusually high transparencies as quantitatively judged by ultraviolet–visible spectroscopy. The method was the in situ generation of silica particles by a two‐step sol–gel procedure in which the required water of hydrolysis was simply absorbed from the air, and the catalyst was generated in situ from a tin salt. Electron microscopy showed that the phase‐separated silica domains were very small (30–50 nm in diameter) and well dispersed, as expected from the transparency of the composites. Stress‐strain measurements in tension indicated that the particles provide very good reinforcement. Ultra‐small‐angle X‐ray scattering data showed that the domain morphology depends strongly on catalyst, but weakly on loading level. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1897–1901, 2003
Benzonitriles: Survey of their importance and scaling of their vibrational frequencies
Authors: Alcolea Palafox M. , Rastogi V. K. , Mittal Lalit
Published: July 2003

This work provides a short survey of the studies carried out on benzonitrile and its derivatives, with special attention on a spectroscopic point of view. The importance and main applications of these molecules are also briefly indicated. For an accurate assignment of their vibrational spectra, the scaling procedures for the wave numbers are described. For this purpose, the performance of semiempirical, ab initio, and density functional methods, with different basis sets, is determined. A “resume” of the main scaling factors to be used in the calculated wave numbers is shown. The results obtained for several benzene derivatives, and in particular for four benzonitriles, are analyzed. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 94: 189–204, 2003
Phosphoryl group differentiating α‐amino acids from β‐ and γ‐amino acids in prebiotic peptide formation
Authors: Jiang Yang , Tan Bo , Chen Zhong‐Zhou , Liu Tong , Zhong Ru‐Gang , Li Yan‐Mei , Stewart David Jeremy , Zhao Yu‐Fen , Jiang Hua‐Liang
Published: July 2003

In recent years β‐amino acids have increased their importance enormously in defining secondary structures of β‐peptides. Interest in β‐amino acids raises the question: Why and how did nature choose α‐amino acids for the central role in life? In this article we present experimental results of MS and 31P NMR methods on the chemical behavior of N‐phosphorylated α‐alanine, β‐alanine, and γ‐amino butyric acid in different solvents. N‐Phosphoryl α‐alanine can self‐assemble to N‐phosphopeptides either in water or in organic solvents, while no assembly was observed for β‐ or γ‐amino acids. An intramolecular carboxylic–phosphoric mixed anhydride (IMCPA) is the key structure responsible for their chemical behaviors. Relative energies and solvent effects of three isomers of IMCPA derived from α‐alanine (2a–c), with five‐membered ring, and five isomers of IMCPA derived from β‐alanine (4a–e), with six‐membered ring, were calculated with density functional theory at the B3LYP/6‐31G** level. The lower relative energy (3.2 kcal/mol in water) of 2b and lower energy barrier for its formation (16.7 kcal/mol in water) are responsible for the peptide formation from N‐phosphoryl α‐alanine. Both experimental and theoretical studies indicate that the structural difference among α‐, β‐, and γ‐amino acids can be recognized by formation of IMCPA after N‐phosphorylation. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 94: 232–241, 2003
Case for projectile kinetic energy gain in stopping power studies
Authors: Cabrera‐Trujillo R. , Sabin J. R. , Öhrn Y. , Deumens E.
Published: July 2003

Under certain collision conditions, a swift ion projectile colliding with a target will gain rather than lose kinetic energy, contrary to the standard conception of stopping power. In this work, we consider the conditions for such a collision such that the energy loss is negative, that is, that there will be projectile kinetic energy gain. In particular, for a target initially in the ground state we find that the projectile gains kinetic energy only when charge exchange and de‐excitation processes are involved. This occurs when the electron affinity of the projectile is larger than the ionization potential of the target. Consequences of this effect are analyzed. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 94: 215–221, 2003
DHP‐insensitive L‐type‐like Ca channel of ascidian acquires sensitivity to DHP with single amino acid change in domain III P‐region
Authors: Izumi-Nakaseko Hiroko , Yamaguchi Shinji , Ohtsuka Yukio , Ebihara Tatsuhiko , Adachi-Akahane Satomi , Okamura Yasushi
Published: July 2003

TuCa1, an ascidian homolog of L‐type Ca channel α1‐subunit, has many critical sites required for binding 1,4‐dihydropyridines (DHPs), but is insensitive to DHPs and methyl 2,5‐dimethyl‐4‐[2‐(phenylmethyl)benzoyl]‐1H‐pyrrole‐3‐carboxylate (FPL‐64176). We have substituted Ser for Ala1016 at the P‐region of domain III in TuCa1 (TuCa1/A1016S) and functionally expressed the channel in Xenopus oocyte along with rabbit α2/δ and β2b. TuCa1/A1016S has gained DHP sensitivity as high as that of a mammalian neuronal L‐type Ca channel (rbCII), but remained resistant to FPL‐64176. These results reinforce the view that Ser1016 in TuCa1/A1016S participates in DHP binding, but there exist other novel sites that fully acquire sensitivity to FPL‐64176.
Different mechanisms are used by insulin to repress three genes that contain a homologous thymine‐rich insulin response element
Authors: Patel Satish , Lipina Christopher , Sutherland Calum
Published: July 2003

Insulin rapidly and completely inhibits expression of the hepatic insulin‐like growth factor binding protein‐1 (IGFBP‐1), phosphoenolpyruvate carboxykinase (PEPCK) and glucose‐6‐phosphatase (G6Pase) genes. This inhibition is mediated through a phosphatidyl inositol 3‐kinase‐dependent regulation of a DNA element, termed the thymine‐rich insulin response element, found within the promoters of each of these genes. This has led to the conclusion that these three promoters are regulated by insulin using the same molecular mechanism. However, we recently found that the regulation of the IGFBP1 but not the PEPCK or G6Pase genes by insulin was sensitive to rapamycin, an inhibitor of mTOR. Here, we present further evidence that different regulatory pathways mediate the insulin regulation of these promoters. Importantly, we identify a protein phosphatase activity in the pathway connecting mTOR to the IGFBP‐1 promoter. These data have major implications for the development of molecular therapeutics for the treatment of insulin‐resistant states such as diabetes and hypertension.
The viral potassium channel Kcv: structural and functional features
Authors: Gazzarrini Sabrina , Severino Maria , Lombardi Mara , Morandi Marzia , DiFrancesco Dario , Van Etten James L , Thiel Gerhard , Moroni Anna
Published: July 2003

The chlorella virus PBCV‐1 was the first virus found to encode a functional potassium channel protein (Kcv). Kcv is small (94 aa) and basically consists of the M1‐P‐M2 (membrane‐pore‐membrane) module typical of the pore regions of all known potassium channels. Kcv forms functional channels in three heterologous systems. This brief review discusses the gating, permeability and modulation properties of Kcv and compares them to the properties of bacterial and mammalian K+ channels.
Computational studies of proton transport through the M2 channel
Authors: Wu Yujie , Voth Gregory A
Published: July 2003

The M2 ion channel is an essential component of the influenza A virus. This low‐pH gated channel has a high selectivity for protons. Evidence from various experimental data has indicated that the essential structure responsible for the channel is a parallel homo‐tetrameric α‐helix bundle having a left‐handed twist with each helix tilted with respect to the membrane normal. A backbone structure has been determined by solid state nuclear magnetic resonance (NMR). Though detailed structures for the side chains are not available yet, evidence has indicated that His37 and Trp41 in the α‐helix are implicated in the local molecular structure responsible for the selectivity and channel gate. More definitive conformations for the two residues were recently suggested based on the known backbone structure and recently obtained NMR data. While two competitive proton‐conductance mechanisms have been proposed, the actual proton‐conductance mechanism remains an unsolved problem. Computer simulations of an excess proton in the channel and computational studies of the His37/Trp41 conformations have provided insights into these structural and mechanism issues.
Pyrenula luteopruinosa sp. nov. from Panama and notes on other members of the genus
Authors: Etayo Javiar , Aptroot André
Published: July 2003

Pyrenula luteopruinosa Etayo & Aptroot is described as new from lowland rainforest on the Pacific coast of Panama. The new name Pyrenula caraibica Aptroot & Etayo and the new combinations Pyrenula chilensis (Fée) Aptroot & F. Berger, Pyrenula cryptothelia (Müll. Arg.) Aptroot & Etayo and Pyrenula hibernica (Nyl.) Aptroot are proposed.
Determinant factors for the formation of the calcium oxalate minerals, weddellite and whewellite, on the surface of foliose lichens
Authors: Giordani Paolo , Modenesi Paolo , Tretiach Mauro
Published: July 2003

The factors influencing the predominance of one of the two mineral forms of calcium oxalate (CO), the monohydrated whewellite (COM) and the di-hydrated weddellite (COD), forming the pruina of the upper cortex of lichens, have been investigated through a simple, sensitive histochemical assay: toluidine blue O (TBO), a metachromatic staining test. The differential reactivity of 43 thalli of 17 pruinose foliose species, supplemented by X-ray diffraction analysis and observations with polarizing and scanning electron microscopy, suggests that the histochemical reactivity of hyphal walls and cementing substances of the upper cortex are related to the density of anionic charges. These factors are probably due to the occurrence of polyuronic acid substances that strongly affects the mineralization of CO. Di-hydrated wedellite is always associated with TBO metachromatic reactivity, and COM with orthochromatic reactivity. When the material has an ambiguous ortho/metachromatic reactivity, COD and COM may occur together. This study presents the first experimental evidence that in lichens CO biomineralization is at least partially biologically controlled.
A late Quaternary record of eolian silt deposition in a maar lake, St. Michael Island, western Alaska
Authors: Muhs Daniel R. , Ager Thomas A. , Been Josh , Bradbury J. Platt , Dean Walter E.
Published: July 2003

Recent stratigraphic studies in central Alaska have yielded the unexpected finding that there is little evidence for full-glacial (late Wisconsin) loess deposition. Because the loess record of western Alaska is poorly exposed and not well known, we analyzed a core from Zagoskin Lake, a maar lake on St. Michael Island, to determine if a full-glacial eolian record could be found in that region. Particle size and geochemical data indicate that the mineral fraction of the lake sediments is not derived from the local basalt and is probably eolian. Silt deposition took place from at least the latter part of the mid-Wisconsin interstadial period through the Holocene, based on radiocarbon dating. Based on the locations of likely loess sources, eolian silt in western Alaska was probably deflated by northeasterly winds from glaciofluvial sediments. If last-glacial winds that deposited loess were indeed from the northeast, this reconstruction is in conflict with a model-derived reconstruction of paleowinds in Alaska. Mass accumulation rates in Zagoskin Lake were higher during the Pleistocene than during the Holocene. In addition, more eolian sediment is recorded in the lake sediments than as loess on the adjacent landscape. The thinner loess record on land may be due to the sparse, herb tundra vegetation that dominated the landscape in full-glacial time. Herb tundra would have been an inefficient loess trap compared to forest or even shrub tundra due to its low roughness height. The lack of abundant, full-glacial, eolian silt deposition in the loess stratigraphic record of central Alaska may be due, therefore, to a mimimal ability of the landscape to trap loess, rather than a lack of available eolian sediment.
The Eastern Beringian voleMicrotus deceitensis(Rodentia, Muridae, Arvicolinae) in Late Pliocene and Early Pleistocene faunas of Alaska and Yukon
Authors: Storer John E.
Published: July 2003

The fossil voleMicrotus deceitensisoccurs in Early Pleistocene deposits at Fort Selkirk, Yukon Territory, and Late Pliocene beds at the type locality, Cape Deceit, Alaska. Analyses of simple vs complex morphotypes in the cheek teeth, and of differentiation of tooth enamel, show that the Cape Deceit sample ofM. deceitensisis less derived, and thus appears to be older, than the Fort Selkirk sample. The fossiliferous deposits at Fort Selkirk are well constrained by fission-track and radiometric dates and are 1.5 to 1.7 myr. Sediments at Cape Deceit bear a normal magnetic polarity, are correlated with the Olduvai subchron, and probably are latest Pliocene.
The effect of capsular tightening on humeral head translations
Authors: Werner Clément M. L. , Nyffeler Richard W. , Jacob Hilaire A. C. , Gerber Christian
Published: July 2003

Idiopathic or surgical tightening of the glenohumeral joint capsule may cause displacement of the humeral head relative to the glenoid fossa and favor the development of instability and/or osteoarthritis.

In the present investigation the relative position of the humerus to the glenoid fossa was determined at the end of the ranges of eight different passive movements before and after selective capsular plication in eight cadaveric shoulders to study the effects of selective capsular plications on the kinematics of the shoulder.

While the capsule was in its unaltered state, translation of the humeral head was 3.8 mm superiorly in abduction, 7.3 mm antero‐superiorly in flexion. In internal rotation in 0°, 45° and 90° of abduction the head moved 6.1, 8.0 and 12.0 mm antero‐inferiorly. In external rotation at 0° of abduction the translation was 0.9 mm antero‐inferiorly, at 45° and 90° of abduction it was 4.3 and 5.6 mm postero‐inferiorly, respectively.

Plications of the anterior part of the capsule reproducibly and significantly either increased or decreased translations during flexion (up to 5.9 mm anteriorly and up to 3.8 mm inferiorly), external rotation (up to 2.9 mm posteriorly and 1 mm inferiorly) and internal rotation (from 5.5 mm posteriorly to 2 mm anteriorly and up to 2.2 mm superiorly). Posterior plications had only little effect on translations (mainly a decrease of anterior translation during flexion of 2.8 mm).

Clinical relevance: The ‘obligate’ glenohumeral translations which occur towards the end of passive shoulder movements are altered in a reproducible fashion by tightening specific parts of the glenohumeral joint capsule, as often carried out in treatment of shoulder instability. These alterations of the kinematics of the glenohumeral joint may be relevant for the development of static subluxation and osteoarthitis as seen after too tight plication in the treatment of instability [Int. Orthop. (SICOT) 67‐B (1985) 709; J. Bone Joint Surg. Am. 72 (1990) 1193; J. Bone Joint Surg. Am. 66‐A (1984) 169; J. Bone Joint Surg. Am. 65 (1983) 456]. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.