bluuebunny/crossref_metadata_2025_split huggingface dataset:
Field ion microscopic studies of the CO oxidation on platinum: Field ion imaging and titration reactions
Authors: Gorodetskii V. , Drachsel W. , Block J. H. 
Published: July 2002

Elementary steps of the CO oxidation—which are important for understanding the oscillatory behavior of this catalytic reaction—are investigated simultaneously on different Pt-single crystal surfaces by field ion microscopy. Due to preferential ionization probabilities of oxygen as imaging gas on those surface sites, which are adsorbed with oxygen, these sites can be imaged in a lateral resolution on the atomic scale. In the titration reaction a COad-precovered field emitter surface reacts with gaseous oxygen adsorbed from the gas phase or, vice versa, the Oad-precovered surface with carbon monoxide adsorbed from the gas phase. The competition of the manifold of single crystal planes exposed to the titration reaction at the field emitter tip is studied.The surface specificity can be documented in the specific reaction delay times of the different planes and in the propagation rates of the reaction-diffusion wave fronts measured on these individual planes during the titration reaction with a time resolution of 40 ms. At 300 K the COad-precovered surfaces display the {011} regions, precisely the {331} planes as the most active, followed by {012}, {122}, {001}, and finally by {111}. Reaction wave fronts move with a velocity of 8 Å/s at {012}, with ≊0.8 Å/s at {111}, and have a very fast ‘‘switch-on’’ reaction at the (001) plane with 500 Å/s. At higher temperature, T=350 K, an acceleration of reaction rates is combined with shorter delay times.The titration reaction of a precovered Oad surface with COgas at T=373 K shows the formation of CO islands starting in the {011} regions with a quickly moving reaction front into the other surface areas without showing particular delay times for different surface symmetries. The two reverse titration reactions have a largely different character. The titration of COad with oxygen adsorbed from the gas phase consists of three different steps, (i) the induction times, (ii) the highly surface specific reaction, and (iii) different rates of wave front propagation. The reaction of COgas with a precovered Oad layer on the other hand starts with nucleating islands around the {011} planes from where the whole emitter surface is populated with COad without pronounced surface specifity.
Development of the indirect-drive approach to inertial confinement fusion and the target physics basis for ignition and gain
Authors: Lindl John 
Published: July 2002

Inertial confinement fusion (ICF) is an approach to fusion that relies on the inertia of the fuel mass to provide confinement. To achieve conditions under which inertial confinement is sufficient for efficient thermonuclear burn, a capsule (generally a spherical shell) containing thermonuclear fuel is compressed in an implosion process to conditions of high density and temperature. ICF capsules rely on either electron conduction (direct drive) or x rays (indirect drive) for energy transport to drive an implosion. In direct drive, the laser beams (or charged particle beams) are aimed directly at a target. The laser energy is transferred to electrons by means of inverse bremsstrahlung or a variety of plasma collective processes. In indirect drive, the driver energy (from laser beams or ion beams) is first absorbed in a high-Z enclosure (a hohlraum), which surrounds the capsule. The material heated by the driver emits x rays, which drive the capsule implosion. For optimally designed targets, 70%–80% of the driver energy can be converted to x rays. The optimal hohlraum geometry depends on the driver. Because of relaxed requirements on laser beam uniformity, and reduced sensitivity to hydrodynamic instabilities, the U.S. ICF Program has concentrated most of its effort since 1976 on the x-ray or indirect-drive approach to ICF. As a result of years of experiments and modeling, we are building an increasingly strong case for achieving ignition by indirect drive on the proposed National Ignition Facility (NIF).The ignition target requirements for hohlraum energetics, radiation symmetry, hydrodynamic instabilities and mix, laser plasma interaction, pulse shaping, and ignition requirements are all consistent with experiments. The NIF laser design, at 1.8 MJ and 500 TW, has the margin to cover uncertainties in the baseline ignition targets. In addition, data from the NIF will provide a solid database for ion-beam-driven hohlraums being considered for future energy applications. In this paper we analyze the requirements for indirect drive ICF and review the theoretical and experimental basis for these requirements. Although significant parts of the discussion apply to both direct and indirect drive, the principal focus is on indirect drive.
Italian neopatriotism: Debating national identity in the 1990s
Authors: Patriarca Silvana 
Published: July 2002

SummaryThis article discusses some of the distinguishing features of the debate over national identity that took place in Italy in the 1990s. Reacting against the threats of the Lega Nord and in response to the new ideological and political landscape of the post-Cold War order, a number of Italian intellectuals rediscovered the value of patriotism. Searching for the origins of the Italians' allegedly weak sense of national identity, some questioned the Resistance and the party system that originated from it. While this historical revisionism has been the object of well-deserved criticism, there is another type of thematization of identity which has received less attention: it deploys the old notion of an ‘Italian character’, which appears frequently in the press and the media. The article shows that this discourse, too, is a way of articulating patriotism, and then reflects on the meaning that this reconfiguration of ideologies and identities acquires in the new context, both domestic and international.
Productivity with word order and morphology: a comparative look at children with SLI and children with normal language abilities
Authors: Conti‐Ramsden Gina , Windfuhr Kirsten 
Published: July 2002

AbstractThe study investigated the development of grammatical categories (verb and noun) in young language learners. Specifically, children's ability to mark correctly the semantic roles of agent and patient was investigated. Second, children's productive use of the present tense progressive —ing, past tense —ed, third person singular —s and plural —s inflection was investigated. Twenty‐eight children with specific language impairment (SLI) with a mean language age of 35 months and 28 children with normal language (NL) with a mean language age of 34 months were exposed to four novel verbs and four novel nouns during ten experimental child‐directed play sessions. The lexical items were modelled with four experimentally controlled argument structures. Furthermore, both groups of children were administered structured tests of grammatical morphology (involving both verbs and nouns). First, children in both groups did not correctly mark semantic roles for agent and patient, unless specific semantic roles had already been modelled in the linguistic input by the experimenter. Second, children's productive use of grammatical morphology in their spontaneous utterances was better for nouns than verbs. Importantly, however, children with NL were significantly better at marking verbs for past tense than in children with SLI, although both groups performed poorly overall. These findings are discussed in relation to current theories of normal and impaired language development, in particular the usefulness of tense marking as a clinical marker of preschool children with SLI.
Identification of Novel Graded Polarity Actin Filament Bundles in Locomoting Heart Fibroblasts: Implications for the Generation of Motile Force
Authors: Cramer Louise P. , Siebert Margaret , Mitchison Timothy J. 
Published: July 2002

We have determined the structural organization and dynamic behavior of actin filaments in entire primary locomoting heart fibroblasts by S1 decoration, serial section EM, and photoactivation of fluorescence. As expected, actin filaments in the lamellipodium of these cells have uniform polarity with barbed ends facing forward. In the lamella, cell body, and tail there are two observable types of actin filament organization. A less abundant type is located on the inner surface of the plasma membrane and is composed of short, overlapping actin bundles (0.25–2.5 μm) that repeatedly alternate in polarity from uniform barbed ends forward to uniform pointed ends forward. This type of organization is similar to the organization we show for actin filament bundles (stress fibers) in nonlocomoting cells (PtK2 cells) and to the known organization of muscle sarcomeres. The more abundant type of actin filament organization in locomoting heart fibroblasts is mostly ventrally located and is composed of long, overlapping bundles (average 13 μm, but can reach up to about 30 μm) which span the length of the cell. This more abundant type has a novel graded polarity organization. In each actin bundle, polarity gradually changes along the length of the bundle. Actual actin filament polarity at any given point in the bundle is determined by position in the cell; the closer to the front of the cell the more barbed ends of actin filaments face forward.
By photoactivation marking in locomoting heart fibroblasts, as expected in the lamellipodium, actin filaments flow rearward with respect to substrate. In the lamella, all marked and observed actin filaments remain stationary with respect to substrate as the fibroblast locomotes. In the cell body of locomoting fibroblasts there are two dynamic populations of actin filaments: one remains stationary and the other moves forward with respect to substrate at the rate of the cell body.
This is the first time that the structural organization and dynamics of actin filaments have been determined in an entire locomoting cell. The organization, dynamics, and relative abundance of graded polarity actin filament bundles have important implications for the generation of motile force during primary heart fibroblast locomotion.
Sorting Mechanisms Regulating Membrane Protein Traffic in the Apical Transcytotic Pathway of Polarized MDCK Cells
Authors: Gibson A. , Futter C.E. , Maxwell S. , Allchin E.H. , Shipman M. , Kraehenbuhl J.-P. , Domingo D. , Odorizzi G. , Trowbridge I.S. , Hopkins C.R. 
Published: July 2002

The transcytotic pathway followed by the polymeric IgA receptor (pIgR) carrying its bound ligand (dIgA) from the basolateral to the apical surface of polarized MDCK cells has been mapped using morphological tracers. At 20°C dIgA-pIgR internalize to interconnected groups of vacuoles and tubules that comprise the endosomal compartment and in which they codistribute with internalized transferrin receptors (TR) and epidermal growth factor receptors (EGFR). Upon transfer to 37°C the endosome vacuoles develop long tubules that give rise to a distinctive population of 100-nm-diam cup-shaped vesicles containing pIgR. At the same time, the endosome gives rise to multivesicular endosomes (MVB) enriched in EGFR and to 60-nm-diam basolateral vesicles. The cup-shaped vesicles carry the dIgA/pIgR complexes to the apical surface where they exocytose.
Using video microscopy and correlative electron microscopy to study cells grown thin and flat we show that endosome vacuoles tubulate in response to dIgA/pIgR but that the tubules contain TR as well as pIgR. However, we show that TR are removed from these dIgA-induced tubules via clathrin-coated buds and, as a result, the cup-shaped vesicles to which the tubules give rise become enriched in dIgA/pIgR.
Taken together with the published information available on pIgR trafficking signals, our observations suggest that the steady-state concentrations of TR and unoccupied pIgR on the basolateral surface of polarized MDCK cells are maintained by a signal-dependent, clathrin-based sorting mechanism that operates along the length of the transcytotic pathway. We propose that the differential sorting of occupied receptors within the MDCK endosome is achieved by this clathrin-based mechanism continuously retrieving receptors like TR from the pathways that deliver pIgR to the apical surface and EGFR to the lysosome.
α6 Integrins Are Required for Langerhans Cell Migration from the Epidermis
Authors: Price Abigail A. , Cumberbatch Marie , Kimber Ian , Ager Ann 
Published: July 2002

Topical exposure of mice to chemical allergens results in the migration of epidermal Langerhans cells (LCs) from the skin and their accumulation as immunostimulatory dendritic cells (DCs) in draining lymph nodes. Epidermal cell–derived cytokines have been implicated in the maturation and migration of LCs, but the adhesion molecules that regulate LC migration have not been studied. We hypothesized that integrin-mediated interactions with extracellular matrix components of the skin and lymph node may regulate LC/DC migration. We found that α6 integrins and α4 integrins were differentially expressed by epidermal LCs and lymph node DCs. A majority of LCs (70%) expressed the α6 integrin subunit, whereas DCs did not express α6 integrins. In contrast, the α4 integrin subunit was expressed at high levels on DCs but at much lower levels on LCs. The anti-α6 integrin antibody, GoH3, which blocks binding to laminin, completely prevented the spontaneous migration of LCs from skin explants in vitro and the rapid migration of LCs from mouse ear skin induced after intradermal administration of TNF-α in vivo. GoH3 also reduced the accumulation of DCs in draining lymph nodes by a maximum of 70% after topical administration of the chemical allergen oxazolone. LCs remaining in the epidermis in the presence of GoH3 adopted a rounded morphology, rather than the interdigitating appearance typical of LCs in naive skin, suggesting that the cells had detached from neighboring keratinocytes and withdrawn cellular processes in preparation for migration, but were unable to leave the epidermis. The anti-α4 integrin antibody PS/2, which blocks binding to fibronectin, had no effect on LC migration from the epidermis either in vitro or in vivo, or on the accumulation of DCs in draining lymph nodes after oxazolone application. RGD-containing peptides were also without effect on LC migration from skin explants.
These results identify an important role for α6 integrins in the migration of LC from the epidermis to the draining lymph node by regulating access across the epidermal basement membrane. In contrast, α4 integrins, or other integrin-dependent interactions with fibronectin that are mediated by the RGD recognition sequence, did not influence LC migration from the epidermis. In addition, α4 integrins did not affect the accumulation of LCs as DCs in draining lymph nodes.
An EXCEL template for calculation of enzyme kinetic parameters by non-linear regression.
Authors: Hern√°ndez A , Ruiz M T 
Published: July 2002

Abstract
MOTIVATION: An EXCEL template has been developed for the calculation of enzyme kinetic parameters by non-linear regression techniques. The tool is accurate, inexpensive, as well as easy to use and modify. AVAILABILITY: The program is available from http://www.ebi.ac.uk/biocat/biocat.html CONTACT: agustin. hernandez@bio.kuleuven.ac.be
Profile hidden Markov models.
Authors: Eddy S R 
Published: July 2002

Abstract
The recent literature on profile hidden Markov model (profile HMM) methods and software is reviewed. Profile HMMs turn a multiple sequence alignment into a position-specific scoring system suitable for searching databases for remotely homologous sequences. Profile HMM analyses complement standard pairwise comparison methods for large-scale sequence analysis. Several software implementations and two large libraries of profile HMMs of common protein domains are available. HMM methods performed comparably to threading methods in the CASP2 structure prediction exercise.
Registration of the expression patterns of Drosophila
segmentation genes by two independent methods
Authors: Myasnikova Ekaterina , Samsonova Anastassia , Kozlov Konstantin , Samsonova Maria , Reinitz John 
Published: July 2002

Abstract
Motivation: To construct an integrated map of Drosophila segmentation gene expression from partial data taken from individual embryos.
Results: Spline and wavelet based registration techniques were developed to register Drosophila segmentation gene expression data. As ground control points for registration we used the locations of extrema on gene expression patterns, represented in 1D. The registration method was characterized by unprecedented high accuracy. A method for constructing the integrated pattern of gene expression at cellular resolution was designed. These patterns were constructed for 9 segmentation genes belonging to gap and pair-rule classes.
Availability: Programs running on SPARC/SunOS 5.0 platform or Alpha/DU 4.0E systems may be obtained from the authors.
Contact: myasnikova@fn.csa.ru
* To whom correspondence should be addressed.
Relative potential for selection of fluoroquinolone-resistant Streptococcus pneumoniae strains by levofloxacin: comparison with ciprofloxacin, sparfloxacin and ofloxacin
Authors: Drugeon H. B. , Juvin M. E. , Bryskier A. 
Published: July 2002

Abstract
The aim of this study was to evaluate the relative potential of levofloxacin to select for resistance in Streptococcus pneumoniae in comparison with ciprofloxacin, sparfloxacin and ofloxacin. Two S. pneumoniae strains were studied; HBD 153 (parental strain, serotype 3) and HBD 964 (selected from the parental strain in an experimental mouse peritonitis infection model). MICs for the two strains were, respectively: 2 and 2 mg/L for ciprofloxacin; 2 and 4 mg/L for ofloxacin; 0.5 and 1 mg/L for sparfloxacin; 2 and 2 mg/L for levofloxacin. In-vitro, with 4 × MIC as the selection concentration, no mutant was obtained with strain HBD 153 (mutation frequency &lt;10 −8 ). With HBD 964, the mutation frequency was 9 × 10 −7 for ofloxacin, 10 −7 for ciprofloxacin, 4 × 10 −5 for sparfloxacin and &lt;10 −8 for levofloxacin. In an immunosuppressed mouse peritonitis model (20 mice per dose), the S. pneumoniae strains were studied with sc doses of ciprofloxacin, sparfloxacin and ofloxacin at 50 mg/kg od, and with sc levofloxacin at a dose of 10 and 50 mg/kg od, or 10 and 50 mg/kg bid. The MICs for strains isolated after antibiotic treatment and the mutation frequencies at 4 × MIC were determined. Against HBD 153, sparfloxacin was the most active treatment, followed by levofloxacin 10 mg/kg and 50 mg/kg bid, but strains identical to HBD 964 (showing a resistant variant at 4 × MIC) were selected by sparfloxacin. Against HBD 964, levofloxacin (10 mg/kg and 50 mg/kg) was the most active drug. Highly resistant mutants were selected by ofloxacin and ciprofloxacin, but not by sparfloxacin and levofloxacin. In conclusion, the relative potential of levofloxacin to select for fluoroquinolone-resistant S. pneumoniae is lower than that of ciprofloxacin, ofloxacin and sparfloxacin both in vitro and in vivo.
Conserved and nonconserved features of the folding pathway of hisactophilin, a β‐trefoil protein
Authors: Liu Chengsong , Gaspar Joe A. , Wong Hannah J. , Meiering Elizabeth M. 
Published: July 2002

AbstractBased on previous studies of interleukin‐1β (IL‐1β) and both acidic and basic fibroblast growth factors (FGFs), it has been suggested that the folding of β‐trefoil proteins is intrinsically slow and may occur via the formation of essential intermediates. Using optical and NMR‐detected quenched‐flow hydrogen/deuterium exchange methods, we have measured the folding kinetics of hisactophilin, another β‐trefoil protein that has <10% sequence identity and unrelated function to IL‐1β and FGFs. We find that hisactophilin can fold rapidly and with apparently two‐state kinetics, except under the most stabilizing conditions investigated where there is evidence for formation of a folding intermediate. The hisactophilin intermediate has significant structural similarities to the IL‐1β intermediate that has been observed experimentally and predicted theoretically using a simple, topology‐based folding model; however, it appears to be different from the folding intermediate observed experimentally for acidic FGF. For hisactophilin and acidic FGF, intermediates are much less prominent during folding than for IL‐1β. Considering the structures of the different β‐trefoil proteins, it appears that differences in nonconserved loops and hydrophobic interactions may play an important role in differential stabilization of the intermediates for these proteins.
Endogenous/Exogenous Nanovaccines Synergistically Enhance Dendritic Cell‐Mediated Tumor Immunotherapy
Authors: Zhang Yu , Li Qiang , Ding Meng , Xiu Weijun , Shan Jingyang , Yuwen Lihui , Yang Dongliang , Song Xuejiao , Yang Guangwen , Su Xiaodan , Mou Yongbin , Teng Zhaogang , Dong Heng 
Published: February 2023

AbstractTraditional dendritic cell (DC)‐mediated immunotherapy is usually suppressed by weak immunogenicity in tumors and generally leads to unsatisfactory outcomes. Synergistic exogenous/endogenous immunogenic activation can provide an alternative strategy for evoking a robust immune response by promoting DC activation. Herein, Ti3C2 MXene‐based nanoplatforms (termed MXP) are prepared with high‐efficiency near‐infrared photothermal conversion and immunocompetent loading capacity to form endogenous/exogenous nanovaccines. Specifically, the immunogenic cell death of tumor cells induced by the photothermal effects of the MXP can generate endogenous danger signals and antigens release to boost vaccination for DC maturation and antigen cross‐presentation. In addition, MXP can deliver model antigen ovalbumin (OVA) and agonists (CpG‐ODN) as an exogenous nanovaccine (MXP@OC), which further enhances DC activation. Importantly, the synergistic strategy of photothermal therapy and DC‐mediated immunotherapy by MXP significantly eradicates tumors and enhances adaptive immunity. Hence, the present work provides a two‐pronged strategy for improving immunogenicity and killing tumor cells to achieve a favorable outcome in tumor patients.
Advances in Gelatin Bioinks to Optimize Bioprinted Cell Functions
Authors: Asim Saad , Tabish Tanveer A. , Liaqat Usman , Ozbolat Ibrahim T. , Rizwan Muhammad 
Published: February 2023

AbstractGelatin is a widely utilized bioprinting biomaterial due to its cell‐adhesive and enzymatically cleavable properties, which improve cell adhesion and growth. Gelatin is often covalently cross‐linked to stabilize bioprinted structures, yet the covalently cross‐linked matrix is unable to recapitulate the dynamic microenvironment of the natural extracellular matrix (ECM), thereby limiting the functions of bioprinted cells. To some extent, a double network bioink can provide a more ECM‐mimetic, bioprinted niche for cell growth. More recently, gelatin matrices are being designed using reversible cross‐linking methods that can emulate the dynamic mechanical properties of the ECM. This review analyzes the progress in developing gelatin bioink formulations for 3D cell culture, and critically analyzes the bioprinting and cross‐linking techniques, with a focus on strategies to optimize the functions of bioprinted cells. This review discusses new cross‐linking chemistries that recapitulate the viscoelastic, stress‐relaxing microenvironment of the ECM, and enable advanced cell functions, yet are less explored in engineering the gelatin bioink. Finally, this work presents the perspective on the areas of future research and argues that the next generation of gelatin bioinks should be designed by considering cell–matrix interactions, and bioprinted constructs should be validated against currently established 3D cell culture standards to achieve improved therapeutic outcomes.