bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Atomic Structure of the UO2 (111) Surface and the Effects of Additional Surface Oxygen Studied by Elevated Temperature STM
Authors: Muggelberg C. , Castell M. R. , Briggs G. A. D. , Goddard D. T. 
Published: August 2003

The structure of the UO 2+x (111) surface has been investigated by elevated temperature STM. Images of atomic terraces reveal two different types of surface termination. One of them corresponds to the stoichiometric UO 2 (111) surface and can be resolved atomically in empty state images above ~ 1.6 V sample bias. The observed (1 × 1) ordering is thought to be due to uranium states because its occurrence corresponds to the bottom of the empty uranium 5f band. On these terraces mobile oxygen forms a local [Formula: see text] superstructure. The other terrace type observed on top of the UO 2+x (111) surface is thought to be a phase of a higher uranium oxide which has grown epitaxially.
One-Dimension Chains of Structural Defects on the Surface of Sapphire and their Role in Adsorption of Alkali Atoms
Authors: Bonch-Bruevich A. M. , Vartanyan T. A. , Maksimov Yu. N. , Przhibelskii S. G. , Khromov V. V. 
Published: August 2003

Alkali adsorption on the (0001) surface of the monocrystalline α- Al 2 O 3 was studied by means of laser-simulated desorption. It was found that alkali atoms are adsorbed mostly on the centers with the surface concentration of about 1013 cm -2. Although the temperature dependence of surface coverage is consistent with the conventional Langmuir model for adsorption on the isolated centers, the estimated adsorption energy of about 1 eV is too large to account for the quantum yield of the photodesorption process, which is as high as 5 ×10-5. To resolve this contradiction we assumed that adsorption centers make up chains along the steps on the surface. Lateral interactions between neighboring adatoms were accounted for by means of methods developed for the Ising model. Theoretical results are in agreement with the experiment.
Acetylene C2H2 Adsorbed onto MgO(001): Structure and Thermodynamics
Authors: Ferry D. , Suzanne J. , Hoang P. N. M. , Girardet C. 
Published: August 2003

Structural and thermodynamical LEED experiments were performed on MgO(001) single crystal cleaved in situ under ultrahigh vacuum conditions within the temperature range of 40–94 K. We observe a commensurate (2 × 2) herringbone structure containing two molecules and having two glide planes. The isosteric heat of adsorption Qst = 6.9 ± 0.4 kcal · mole -1 and lateral interoction energy Q// = 3.1 ± 0.4 kcal · mole -1 have been measured and compared with semiempirical potential calculations. The influence of the molecular motions on the calculated isosteric heat of adsorption is evaluated to take into account temperature effects.
Variation of the Local Work Function of MgO(001) Surface by Palladium Deposition
Authors: Di Salvo J.-P. , Gillet E. 
Published: August 2003

A study of ultrathin palladium films deposited on MgO(100) is reported. The early studies of the growth are in situ investigated at 300 K and 600 K by secondary ion mass spectrometry used in static mode (SSIMS). The variation of ion species typical of the metal deposit ( Pd +, [Formula: see text]) and of the substrate ( MgO +) is analyzed as a function of the deposit mean thickness. The results show that Pd films grow initially by sticking of isolated adatoms on sites leading to the formation of 2D islands until a critical coverage which depends on the temperature. Thereafter a second layer begins to grow that leads to 3D flat clusters at high temperatures. The SSIMS method enables us to determine quantitatively the local work function of both palladium and MgO surfaces. Changes in the electronic structure of these systems during deposition of the two first Pd layers suggest a strong influence of the oxide support.
SSIMS and XPS Studies of Reconstruction of Alumina-Supported Rh Particles
Authors: Stará I. , Di Salvo J.-P. , Nehasil V. , Matolín V. , Gillet E. 
Published: August 2003

Rhodium particles were vapor-deposited on (-1012) α-alumina and polycrystalline γ-alumina substrates. Variations of morphological parameters during the growth and/or thermal annealing in vacuum, oxygen and CO atmosphere have been investigated by means of static SIMS and XPS. The ratios of Rh/substrate ion species and the Rh 3d electron binding energy variations indicated changes in metal coverage given by particle size and dispersion variations. The heating of as-deposited particles in vacuum led to the particle coalescence. On the other hand the oxygen interactions with particles gave an increase of particle dispersion.
Chemisorption Geometry, Vibrational Spectra, and Thermal Desorption of Formic Acid on TiO2(110)
Authors: Chambers S. A. , Henderson M. A. , Kim Y. J. , Thevuthasan S. 
Published: August 2003

We have used high-energy X-ray photoelectron spectroscopy and diffraction (XPS/XPD), low-energy electron diffraction (LEED), high-resolution electron energy loss spectroscopy (HREELS) and temperature-programmed desorption (TPD) to determine the molecular orientation, long-range order, vibrational frequencies, and desorption temperatures for formic acid and its decomposition products on TiO 2(110). Molecular adsorption occurs at coverages approaching one monolayer, producing a weakly ordered (2 × 1) surface structure. High-energy XPD reveals that the formate binds rigidly in a bidentate fashion through the oxygens to Ti cation rows along the [001] direction with an O–C–O bond angle of 126 ± 4°. During TPD some surface protons and formate anions recombine and desorb as formic acid above 250 K. However, most of the decomposition products follow reaction pathways leading to H 2 O , CO and H 2 CO desorption. Water is formed in TPD below 500 K via the abstraction of lattice oxygen by deposited acid protons.
Growth and Analysis of Red, Green and Blue Luminescent Oxide Thin Films
Authors: Hirata G. A. , Mckittrick J. , Devlin D. 
Published: August 2003

The growth and characterization of europium ( Eu 3+) and terbium ( Tb 3+) doped yttrium aluminum garnet ( Y 3 Al 5 O 12 or YAG) and undoped ZnGa 2O4 photoluminescent thin films deposited on sapphire substrates at 400°C by excimer pulsed laser ablation is reported. Smooth, continuous 500-nm-thick amorphous films were produced with compositions depleted in oxygen. Luminescence measurements on the as-deposited and on annealed samples revealed that heat treatments at temperatures > 800°C were necessary to induce crystallization and reoxygenate, which coincided with the onset of luminescence. Annealing produced randomly oriented grains on the order of 15-200 nm.
Scanning Force Microscopy Study of Ultrathin Films of Nickel-Phthalocyanine on Graphite
Authors: Santucci S. , Di Nardo S. , Lozzi L. , Ottaviano L. , Passacantando M. , Picozzi P. 
Published: August 2003

Small amounts of purified nickel-phthalocyanine (Ni-PC) have been deposited at room temperature in ultrahigh vacuum onto highly oriented pyrolytic graphite, and studied "in situ" and "ex situ" (in air) with two different atomic force microscopes. The measurements have been taken on samples as prepared either subsequently annealed at 300°C. The growth mode is not uniform; the PC molecules coalesce into small submicrometric crystallites in the critical size range where the transition from the α to the β crystalline phase of phthalocyanines takes place. We show images of both α-like and β-like crystallites. A contact mode AFM image of an α-like crystallite showing intramolecular resolution is also presented.
Structural and Phase Transitions on Water Ice Surface Under HCl Exposure: Implication for Stratosphere Conditions
Authors: Persiantseva N. M. , Popovicheva O. B. , Rakhimova T. V. 
Published: August 2003

The HCl-ice interaction has been investigated over a wide HCl pressure range of 10-7–10-4 Torr and ice temperatures 150–240 K. The Three characteristic values for HCl uptake efficiency were obtained which indicate the change of phase state and structure of the ice surface at increasing HCl pressure. The low value γ ≈ 0.1 ± 0.02 corresponds to HCl vapor interaction with pure ice and is realized at the atmosphere conditions. The value γ ≈ 0.5 ± 0.1 indicates the formation of hexahydrate HCl • 6H 2 O with increase of HCl pressure. And the largest value of γ ≈ 0.8 ± 0.1 is observed at appearance of liquid or amorphous solid 4:1 H 2O:HCl. The HCl uptake kinetics is analyzed. The flow of HCl molecules from the ice surface into the bulk is shown to play an important role in the redistribution of HCl molecules. It defines a low surface concentration of the adsorbed HCl molecules under stratospher condition at early times of interaction.
Co as Adsorbate and Reaction Product in the Systems Fe(110)/Cs+Co and Fe(110)/Cs+Co2
Authors: Seyller Th. , Rührnschopf K. , Borgmann D. , Wedler G. 
Published: August 2003

The effect of preadsorbed Cs on the electronic structure and thermal stability of CO adsorbed at 80 K on Fe(110) has been studied using ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS). With increasing Cs coverage the O1s and C1s core levels of CO are shifted to lower binding energies (-0.8 eV). In the presence of one-monolayer Cs the thermal stability of CO is enhanced, leading to a decomposition temperature of about 510 K, a value roughly 100 K higher than on the clean Fe(110) surface (~ 420 K). This is explained in terms of an increased back-donation leading to an electrostatic interaction between CO and Cs. These results are compared to the properties of CO which is formed when CO 2 is adsorbed on the Cs-precovered Fe(110) surface, CO formed from adsorbing CO 2 shows neither core level binding energy shift nor enhanced thermal stability. It is concluded that CO formed from adsorbing CO 2 is not affected by the preadsorbed Cs, i.e. there is no or at least significantly less increased backbonding and therefore no electrostatic interaction between Cs and CO in that system. It seems to be in a state comparable to the state of CO in the Fe(110)/CO adsorption system.
Elementary Processes in Molecular Beam Epitaxy Studied by in situ Scanning Electron Microscopy
Authors: Inoue N. 
Published: August 2003

The recent advancement in the in situ scanning electron microscopy of molecular beam epitaxy of GaAs is reviewed. The topics include two-dimensional (2D) nucleation and growth, three-dimensional (3D) roughening processes, 2D-to-step-propagation growth mode change and annealing processes after growth. In the nucleation-and-growth mode, delayed island nucleation and nonlinear change of surface coverage are found. The mechanism of delayed nucleation is discussed in terms of site-dependent successive atomic layer growth processes. It is shown that under a critical growth condition between the 2D mode and the step propagation mode, the local growth mode changes from the 2D mode to the step propagation mode. It is found that there are three types of surface roughening, or onset of 3D growth. A 3D/2D/1D growth mode phase diagram is obtained. Some of the results are compared with the growth of Si on (111) surface. The behavior of monolayer-deep holes during postgrowth annealing is observed. It is found that some holes are left for a long time and form big holes with each other. They extend in the [110] direction but, at the same time, shrink in the [1-10] direction. Finally, they shrink in both directions and disappear .It takes about 10 min for all the holes to disappear. Related work by other authors is briefly described.
Giant Faceting of Vicinal Si(001) Induced by Au Adsorption
Authors: Heringdorf F.-J. Meyer Zu , Kähler D. , Horn-Von Hoegen M. , Schmidt Th. , Bauer E. , Copel M. , Minoda H. 
Published: August 2003

4° vicinal Si(001) shows perfectly ordered terraces with a width of 4 nm which are separated by double steps. Adsorption of Au at 800°C results in a dramatic change of the step morphology: the surface decomposes into areas which are perfectly flat with a (001) orientation and (119) facets, which compensate for the macroscopic miscut. Extremely straight superterraces with a length limited only by the size of the sample (here 4 mm) and a width ranging from 400 nm to 4 μm are formed by massive Si mass transport. The extreme aspect ratio of 1:10 000 of this submicron structure is attributed to a heterogeneous nucleation process. SPA-LEED reveals a new, Au-induced incommensurate 5×3.2 reconstruction above a critical coverage as the driving force for the formation of large elongated (001) terraces. LEEM shows the strongly anisotropic nucleation process in vivo. Dark field imaging and microspot LEED techniques have been used to determine the influence of the different 5×3.2 domain orientations on the growth behavior of the (001) superterraces. The majority of domain terraces grow with a speed of more than 10 μm per second. The width and area of the (001) terraces increase proportionally to the Au coverage. The steps of the vicinal surface are accumulated in irregular step bunches. With further increasing Au coverage the step bunches are transformed into well-defined facets with a (119) orientation, as determined by SPA-LEED. The kinetics of the faceting process have been studied with SPA-LEED, REM, STM, and light diffraction using a HeNe laser, because the typical size of the superterraces is of the order of the wavelength of visible light: the resulting structure is visible to the bare eye. The parallel arrangement of superterraces acts as an irregular optical phase grating: illumination with white light results in stripes of all possible diffraction colors.
Saliva Flow, pH, Buffer Capacity, and Colonization by <i>Streptococcus mutans</i> during and after Radical Radiotherapy of Head and Neck Tumours
Authors: Beer Karl T. , Zehnder Diego , Lussi Adrian , Greiner Richard H. 
Published: August 2003

<i>Background:</i> How does oral health (saliva pH, buffer capacity, and colonization with <i>Streptococcus mutans</i>) change because of reduced salivary flow during and after radical radiotherapy of head and neck carcinoma dependent on ipsilateral or bilateral parotid irradiation? <i>Patients and Methods:</i> 20 consecutive patients who were radically irradiated because of head and neck carcinomas were studied. They were evaluated before radiotherapy, weekly during therapy, and 6 weeks after the end of treatment. Flow rate, pH and buffer capacity of saliva, and colonization with <i>S. mutans</i> were tested. <i>Results:</i> Stimulated saliva secretion rate dropped in the first radiotherapy week in both groups (p < 0.006). This effect was more pronounced in patients with bilateral parotid gland radiation (BPR) in comparison with unilateral parotid gland radiation (UPR). Depending on dose saliva production declined exponentially up to the end of treatment. No rebound was found up to 6 weeks after the end of therapy, a trend towards a further saliva production was observed. Stimulated saliva was significantly diminished when compared to production before the start of treatment (p < 0.003 for UPR and p < 0.001 for BPR). Buffer capacity was reduced parallel to the saliva deficit. The pH of saliva decreased from a mean of 7.3 before treatment to 6.3 at the end of radiotherapy and did not recover for patients with BPR. For patients with UPR, the pH decreased from a mean of 7.8 to 7.4 and remained constant. Colonization with <i>S. mutans</i> increased during treatment and stayed high after the end of radiotherapy. <i>Conclusion:</i> Saliva production is exponentially reduced during radiotherapy, starting in the first week of treatment. Recovery is not observed up to 6 weeks after therapy. Buffer capacity and pH decline during radiotherapy in relation to saliva loss. Colonization by <i>S. mutans</i> increases markedly during radiotherapy and remained high afterwards.
Pathologically Proven Cavernous Angiomas of the Brain following Radiation Therapy for Pediatric Brain Tumors
Authors: Baumgartner James E. , Ater Joann L. , Ha Chul S. , Kuttesch John F. , Leeds Norman E. , Fuller Greg N. , Wilson Ronald J. 
Published: August 2003

Lesions consistent with cavernous angiomas (CAs) of the brain are sometimes seen on MRI scans of the brains of patients who received radiation therapy for brain tumors as children. The lesions appear years later within brain tissue that was included in radiation fields. It is unclear whether these MRI-detected lesions are true CAs or a pathological variant. This study reports the clinical, radiographical, and pathological findings in 3 cases of radiation-induced CAs of the brain. From 1995 to 1997, 3 patients previously treated with radiation therapy (45– 55 Gy) for pediatric brain tumors (medulloblastoma, ependymoma, and a presumed midbrain astrocytoma) underwent resections of symptomatic and enlarging lesions that were consistent with a CA of the brain. All of the lesions occurred within fields of prior irradiation. None of the patients had received chemotherapy as part of their cancer treatment. CA-presenting symptoms included seizures, cranial nerve deficits, and headaches. The lesions appeared 7–19 years after radiation therapy and slowly enlarged on subsequent imaging studies. MRI scans of the lesions revealed characteristics typical of CA. The lesions became symptomatic 1–5 years after they were initially noted. Surgical resection was performed 1–2 years after symptoms began. The age at resection ranged from 15 to 23 years (10–21 years after radiation therapy). Pathological analysis of the three lesions showed typical CA characteristics. Some CAs may be caused by radiation therapy for pediatric brain tumors. They are radiologically and pathologically similar to sporadically occurring CAs of the brain and may enlarge over time and become symptomatic. CAs can be safely resected using standard microsurgical techniques.
A Rare Case of Lymphangiomatosis of the Craniocervical Spine in Conjunction with a Chiari I Malformation
Authors: Jea Andrew , McNeil Ann , Bhatia Sanjiv , Birchansky Sherri , Sotrel Ana , Ragheb John , Morrison Glenn 
Published: August 2003

Lymphangiomatosis of the bone is rare. The axial as well as appendicular skeleton may be affected. Neurosurgical consultation may be called for several reasons: (1) lesions involving the calvarium and/or spine; (2) nondiagnostic biopsies from more accessible and less morbid locations, and (3) persistent CSF leak and/or recurrent meningitis. Thus, it is important for the neurosurgeon to be familiar with this disease entity and consider it in the differential diagnoses of multifocal lytic lesions of the axial skeleton. We present a case report of a 4-year-old girl with lymphangiomatosis of the skull base and upper cervical spine with concurrent Chiari I malformation and briefly review the literature.
Daily Dialysis: The Long and the Short of It
Authors: Gotch Frank A. , Levin Nathan W. 
Published: August 2003

There is considerable enthusiasm for daily hemodialysis despite the increased time commitment required of patients because of reported improvements in patient well-being, appetite and blood pressure control. To date, this therapy has been largely empirical and has been defined primarily by treatment time (t) and categorized as short daily hemodialysis (SDHD) with t about 2 h and long nocturnal hemodialysis (LNHD) with t 8–9 h. It is the authors’ view that studies comparing clinical outcome with SDHD and LNHD to conventional hemodialysis (CHD) must have dialysis dosage well defined if they are to provide generalizable results. There is a broad range and overlap in the magnitude of solute removal in reported studies of SDHD, LNHD and CHD, which is illustrated here through kinetic consideration of four solutes: (1) urea; (2) inorganic phosphorus (iP); (3) β<sub>2</sub>-microglobulin (β<sub>2</sub>M) and (4) Na/water. The following observations can be made: (1) Patient subjective reports of increased appetite and protein intake may correlate poorly with kinetic calculation of protein catabolic rate. (2) A model of iP mass balance was developed and indicates that iP removal with CHD is inadequate; current SDHD is also inadequate to highly excessive depending on the dose of dialysis. (3) β<sub>2</sub>M removal with SDHD is virtually the same as reported for LNHD, reflecting major differences in dialyzer membranes used. (4) The decrease in predialysis overhydration is a predictable function of the number of dialyses per week and may be one of the most important benefits of more frequent dialysis. (5) The standard K<sub>t</sub>/V (stdK<sub>t</sub>/V) provides a uniform method of dose calculation but the therapy prescription should also include consideration of the other solutes evaluated above.
Anti-heavy-chain monoclonal antibodies directed to the acidic regions of the factor VIII molecule inhibit the binding of factor VIII to phospholipids and von Willebrand factor
Authors: Villard Sylvie , Grailly Sabrina , Gilles Jean-Guy , Granier Claude , Saint-Remy Jean-Marie , Barrowcliffe Trevor , Raut Sanjeev 
Published: September 2003

SummaryRecent studies have shown that inhibitors develop against acidic regions of the FVIII molecule, which contain important functional sites. However, their mechanisms of inhibition are not well understood. In this study, two anti-human FVIII mouse monoclonal antibodies (MAbs), directed towards the exposed acidic regions of the FVIII molecule, were developed, characterised and their mechanisms of inhibition investigated. The two MAbs, F7B4 and F26F6, had inhibitory titres of 32 and 944 BU/mg respectively, had high affinities for the FVIII molecule (KD ~ nM range) and recognised sequences V357-F360 on the acidic a1 region and E724-L731 on the acidic a2 region of the FVIII heavy-chain (HC), respectively. F7B4 inhibited the rate of FXa generation by activated FVIII, whilst both antibodies inhibited FVIII activation by thrombin and blocked thrombin cleavage of FVIII. Furthermore, F7B4 and F26F6 inhibited FVIII binding to (a) phospholipids (IC50: 77 nM and 40 nM respectively), and (b) VWF (IC50: 93 nM and 267 nM respectively), despite both having HC specificity. Experiments with F(ab’)2 fragments confirmed the above findings. Taken together these data represent novel findings in that anti-acidic HC antibodies can inhibit FVIII function by a variety of mechanisms, in particular by interfering with the binding of FVIII to phospholipids & VWF.
Activated thrombin-activatable fibrinolysis inhibitor attenuates spontaneous fibrinolysis of batroxobin-induced fibrin deposition in rat lungs
Authors: Wu Chengliang , Dong Ningzheng , da Cunha Valdeci , Martin-McNulty Baby , Tran Katherine , Nagashima Mariko , Wu Qingyu , Morser John , Wang Yi-Xin 
Published: September 2003

SummaryStudies have shown that inhibition of TAFI by small peptides enhances pharmacological effects of tPA in animal models of thrombosis, suggesting that TAFI modulates the fibrinolytic system. In this study, we investigated the effect of activated human TAFI (TAFIa) on endogenous fibrinolysis in a rat model of intravascular fibrin deposition. 125I-labeled fibrinogen was injected intravenously followed by a bolus injection of batroxo-bin, a thrombin-like enzyme. Batroxobin cleaved fibrinogen to form insoluble fibrin that was deposited in tissues, including the lungs. This was shown by a decrease of radioactivity in the blood as a result of consumption of 125I-labeled fibrinogen and an elevation of radioactivity in the lungs 5 min following batroxobin administration. Endogenous fibrinolysis was detected by a gradual increase in radioactivity in the blood and a decrease in radioactivity in the lungs at 30 min, an indication of radio-labeled fibrin degradation products (FDPs) being released into the circulation from the tissues. Intravenous administration of human TAFIa dose-dependently attenuated the later phase reduction of radioactivity in the lungs. When the dose of TAFIa was 218 μg/kg, giving a peak plasma level of TAFIa 0.9 ± 0.05 μg/ml, the spontaneous fibrinolysis was completely prevented. These results provide direct evidence that an increase in circulating TAFIa impairs endogenous clot lysis in a rat model of fibrin deposition.