bluuebunny/crossref_metadata_2025 huggingface dataset:
Challenges in Surface Science for a P-in-Si Quantum Computer — Phosphine Adsorption/Incorporation and Epitaxial Si Encapsulation
Authors: Oberbeck Lars , Curson Neil J. , Schofield Steven R. , Hallam Toby , Simmons Michelle Y. , Clark Robert G.
Published: July 2003

We present three important results relating to the fabrication of a quantum computer in silicon: (i) the interaction of the dopant gas phosphine with Si(001), (ii) a comparison of the morphology of epitaxial Si layers grown on clean and on monohydride-terminated Si(001), and (iii) a direct measure of the segregation/diffusion of incorporated P atoms during Si epitaxial growth and annealing. After low phosphine (PH3) dosing of a Si(001) surface dual bias scanning tunneling microscopy was used to identify the PH x(x = 2, 3) species on the surface. Subsequent annealing to 350°C resulted in the P atom from the PH x molecule being incorporated into the surface to form Si–P heterodimers. The threefold coordination that results from incorporation is expected to be advantageous for phosphorus quantum bit fabrication since it will reduce P segregation and diffusion during Si epitaxial overgrowth. One question to be addressed in the encapsulation process for quantum bits is whether the H resist layer needs to be removed or whether we can grow through the hydrogen layer. We demonstrate that five-monolayer-thick epitaxial Si layers deposited at low temperature (250°C) using molecular beam epitaxy have a significantly lower roughness and defect density when grown on a clean Si(001) surface compared to a H-terminated surface. Attempts to encapsulate phosphorus quantum bits at 260°C and to recover the surface quality of the epitaxial layer resulted in P atoms segregating and diffusing to the surface. These results suggest that the hydrogen layer is desorbed first before the P atoms are encapsulated in epitaxial silicon grown at very low temperature (below 250°C) to minimise phosphorus segregation.
Relating Surface Structure and Growth Mode of γ′Fe4N
Authors: Boerma D. O. , Grachev S. Y. , Borsa D. M. , Miranda R. , Gallego J. M.
Published: July 2003

We have grown thin layers of γ′Fe4N on Cu(100) substrates by molecular beam epitaxy in a flow of atomic nitrogen, delivered by a radio-frequency (RF) plasma source. This nitride phase is a ferromagnetic metallic conductor and has interesting properties for device applications. In addition it has an intriguing growth mechanism. In earlier work we found that pure crystalline layers can be grown at substrate temperatures higher than 250°C, with excess nitrogen and in the presence of hydrogen.1 To gain insight into the growth mechanism, we studied the structure and composition with scanning tunneling microscopy (STM), Auger electron spectroscopy (AES), low-energy electron diffraction (LEED) and X-ray diffraction (XRD). This was done for a coverage range of Fe4N on Cu(100) between 0.5 and 30 monolayers (ML) equivalent of Fe, deposited at 400°C, or at 300°C in one case. Here a preliminary account of this study is presented. We found that at sub-ML coverage, first "depressed" (with respect to the Cu surface) islands of Fe–N are formed. Then, on top of these islands a second layer is growing. Subsequently the space between the islands is filled up by a Fe–N layer growing directly on Cu. This gives rise to a smooth surface with patches differing in height by only 0.5 Å. The following layers grow by step-flow growth. The smooth terraces still show patches with a 0.5 Å height difference. The phase is γ′Fe4N with a distorted (p4g-like) structure as observed with LEED and STM, where a p(2 × 2) symmetry is seen. The c(2 × 2) symmetry expected for γ′Fe4N is observed after growing 30 ML or more. A model for the growth mechanism based on our observations is proposed.
Surface Structure and Lattice Dynamics of Alkali Halide Crystals Studied by High-Resolution Ion Scattering
Authors: Kido Yoshiaki , Okazawa Tetsuaki
Published: July 2003

The rumpled surface structure and thermal lattice vibrations of KI(001) and RbI(001) were measured directly by high-resolution medium energy ion scattering (MEIS). The relaxation of interlayer distance between the top and second layer and the rumpling of the top and second layers were determined using the ion shadowing effect with an accuracy of 0.01 Å. From the displaced lattice positions determined above, we derived the dipole moments of the top- and second-layer ions self-consistently employing the polarizabilities estimated from the optical refractive index combined with the Clausius–Mossotti relation. The balance between a short-range force and a long-range Coulombic one made it possible to judge the applicability of the short-range pair potentials proposed so far. We also determined the root-mean-square (rms) thermal vibration amplitudes of the bulk and the top-layer ions together with the correlations of the ions in the [001] and [101] strings by taking various kinds of scattering geometries. The results obtained were compared with those calculated from the molecular dynamics (MD) simulations based on a classical model using the dipole moments determined above and the Born–Mayer type pair potential. The present MEIS results are in overall agreement with the MD simulations.
Friction Force Microscopy Study of the Hydrophilicity of TiO2 Thin Films Deposited by Radio Frequency Magnetron Sputtering
Authors: Sirghi L. , Aoki T. , Hatanaka Y.
Published: July 2003

Atomic force microscopy (AFM) measurements of the tip–sample friction and adhesive forces were used to study the chemical homogeneity of the surface of titanium dioxide thin films deposited by radio frequency magnetron sputtering deposition. As a result of the photocatalytic activity, the film surface turned superhydrophilic by UV light irradiation in air. However, the AFM measurements showed that the surface of titanium dioxide deposited at low gas pressure (1 mTorr) was chemically heterogeneous with grains of very low photocatalytic activity. In the ambient air, due to the capillary condensation of the water vapor at the AFM tip–sample contact, the superhydrophilic regions on the film surface show larger friction and adhesive forces compared to the regions of low hydrophilicity.
The Relationship Between Structural and Catalytic Activity of α and γ-Bismuth-Molybdate Catalysts for Partial Oxidation of Propylene to Acrolein
Authors: Fansuri H. , Pham G. H. , Wibawanta S. , Zhang D. K. , French David
Published: July 2003

Bismuth-molybdate catalysts are known to be effective for catalytic partial oxidation of propylene to acrolein. Their properties and the kinetics and reaction mechanisms for acrolein production have been extensively studied, especially in their basic forms, such as α, β, and γ-bismuth-molybdate. Although the reaction mechanisms have been reported widely in the literature, a general agreement has not been reached, especially from a catalyst-structure point of view. The present contribution reports an effort to understand the structural changes of α and γ-bismuth-molybdate catalysts at varying temperatures as examined using high temperature XRD and to relate the catalyst performance (activity and selectivity) for propylene partial oxidation to acrolein. The XRD analysis was performed at temperature between 250 and 450°C in ambient atmosphere and the Rietveld refinement method was used to extract unit cell parameters. The results showed a distinct similarity between the shapes of the thermal expansion of the catalysts and their activity and selectivity curves, indicating a significant role that the catalyst interatomic structure plays in the overall reaction mechanism.
An STM Observation of the Initial Process of Graphitization at the ${\rm 6H \mbox-SiC}(000{\bar 1})$ Surface
Authors: Naitoh M. , Kitada M. , Nishigaki S. , Toyama N. , Shoji F.
Published: July 2003

We applied scanning tunneling microscopy (STM) as well as low-energy electron diffraction (LEED) to analyze the initial process of graphitization at [Formula: see text] surfaces. After annealing a [Formula: see text] surface at 1200°C, there appeared many domains with a single graphite layer in the STM image. Each graphite domain was azimuthally disordered to each other. Many large and small domains with various periodicities were observed in the STM image taken after annealing the surface at temperatures higher than 1300°C. These STM images can be explained as Moiré patterns due to different combinations of two graphite layers. In a LEED pattern azimuthally rotated graphite 1 × 1 spots are observed together with the fundamental 6H-SiC(0001)(1 × 1) spots, in consistent with the STM result.
Study of a Computational-Time-Saving Scheme for Quantitative Leed Analysis by the Matrix Inversion Method
Authors: Sun Y. Y. , Wee A. T. S. , Huan A. C. H.
Published: July 2003

A computational-time-saving scheme for quantitative LEED analysis by the matrix inversion method was studied. Two computational-time-critical parameters, the number of atomic layers (Nl) in the surface slab and the number of ion-core scattering phase shifts (l max ), were tested for energy dependence. Our study on a Cu(210) surface shows that no dependence of Nl on the incident energy exists in the energy range of LEED (50–400 eV), i.e. using energy-dependent Nl is not feasible. The effect of slab thickness reduction on the precision of the Pendry R-factor based best-fit structure search was then studied. This study provides a guide to the selection of surface slab thickness in quantitative LEED analysis by the matrix inversion method. Also, we show that using an energy-dependent l max can save nearly half of the overall computational time for obtaining a set of I–V curves by the matrix inversion method.
Study of Oxygen on the Three Low Index Diamond Surfaces by XPS
Authors: Makau N. W. , Derry T. E.
Published: July 2003

Nominally clean diamond surfaces have been shown to contain adsorbed foreign atoms on them. Some of the adsorbed atoms have also been known to lead to various surface modifications, a phenomenon that is important in diamond electronics. Establishing the identity and nature of the adsorbed atoms on these surfaces is therefore key to the successful application of diamond in various technological fields.

In this work, X-ray photoelectron spectrometry (XPS) has been used to investigate the three low index diamond surfaces. The results show oxygen as the main foreign atom on these surfaces other than hydrogen, with varying fractions of oxygen monolayer coverage being observed. It is further established that the adsorbed oxygen exists in several bonding configurations, with the energy shifts associated with the various functional groups being determined.
Sulphur-Passivated GaAs Investigation Using High Resolution X-Ray Diffractometry
Authors: Pavlov Konstantin , Jamieson Ian , Jakovidis Greg , Petrakov Anatoly , Punegov Vasily
Published: July 2003

The growth of a MoS2 layer on a GaAs(111) substrate produces a highly strained interface layer, which relaxes via generation of dislocations. Using high-resolution X-ray diffractometry in the triple-axis scheme we investigated this interfacial layer, which results from dipping an epi-ready GaAs wafer in ammonium sulphide, followed by deposition of an RF-sputtered MoS2 layer. The dislocation density revealed from the measurements is of the 106 cm-2. This suggests that high efficiency (~20%) MoS2/GaAs heterojunction photovoltaic devices are feasible.
Atomic Observation of the Sublimation Process of the Pb (111) Surface
Authors: Tanigaki T. , Suzuki H. , Kimura Y. , Kaito C. , Saito Y.
Published: July 2003

The dynamic behavior of the sublimation process using ultrafine Pb particles produced by the gas evaporation technique was examined at the level of atomic resolution using a transmission electron microscope equipped with a real-time video-recording system. The ultrafine Pb particles coated with a carbon layer with a thickness of the order of 5 nm were prepared in the electron microscope by heating particles on carbon film at 300°C. Sublimation of the Pb particle covered with the carbon layer took place above 470°C, which is slightly higher than the melting point of Pb. Sublimation occurred at the surface with a higher surface energy. The sublimation process of the (111) surface was clearly observed at an atomic level. It was found that two- or four-atomic-layer step flow was observed at the (111) surface. At the (111) surface between the stacking faults, two-layer and successive one-layer sublimation occurred.
Crystal Orientation of Silver Films on Silicon Surfaces Revealed by Surface X-Ray Diffraction
Authors: Hata A. , Akimoto K. , Horii S. , Emoto T. , Ichimiya A. , Tajiri H. , Takahashi T. , Sugiyama H. , Zhang X. , Kawata H.
Published: July 2003

We have studied the crystal orientation of Ag thin films on a [Formula: see text] surface using grazing incidence X-ray diffraction with synchrotron radiation. After preparation of a [Formula: see text] surface, 50 ML Ag was deposited on the [Formula: see text] at the substrate temperature of 50–300 K. We found the [Formula: see text] structure at the interface. As for the Ag film, the Ag}111{ plane was mainly grown on the surface. The domain size of the Ag films strongly depends on the substrate temperature of the deposition. The domain size is found to be regulated by an original domain size of the [Formula: see text] surface before Ag deposition, which relates to the surface-structural phase transition. By scattering intensity measurements in the reciprocal lattice space, we found streaky scattering along the [Formula: see text] direction parallel to the surface. This scattering is thought to originate from the CTR (crystal truncation rod) scattering from a sidewall plane of the Ag {111} nanometer-scale crystals.
Incommensurate Structures and Nanoscale Friction at Solid Interfaces
Authors: Kawaguchi Takaaki , Matsukawa Hiroshi
Published: July 2003

In this study, using numerical simulations based on an incommensurate lattice model at the nanoscale, we investigate the lattice structures of pinned surfaces and the lubrication dynamics of surfaces driven by a moving external plate or an external force. When the elasticity of the surface is changed, the maximum static frictional force shows anomalously complicated behavior under certain conditions. The kinetic frictional force shows peculiar resonant-type sliding velocity dependence, which is caused by phonon excitations, and leads to novel behaviors of lubrication.
Theoretical Investigation of NO Oxidation over TiO2-Anatase
Authors: Mguig Basma , Calatayud Monica , Minot Christian
Published: July 2003

We present periodic DFT calculations to study the NO adsorption on stoichiometric (100) and (001) TiO2-anatase surfaces. The adsorption on the Ti atoms, involving an oxidation of the substrate, is very weak. The adsorption on the O atoms, involving a reduction of the substrate, is possible when these atoms are in terminal position. Then, nitrite and nitrates can be formed. The adsorption energy for their formation on an oxygen-terminated slab model is ten times larger than the molecular NO adsorption on a titanium atom.
Structure of Nanoparticles of Aluminum and Silicon Nitrides Produced by RF Plasma
Authors: Sato Takeshi , Kaito Chihiro , Saito Yoshio
Published: July 2003

AlN and Si3N4 particles with sizes of the order of 50 nm were produced by passing Al and Si smoke particles of the order of 50 nm in size through a plasma field. The resulting particles showed the characteristic crystal structure of a nitride. When Al and Si particles were produced in a mixture gas of N2 and Ar without plasma, the particles produced were covered with an amorphous nitride layer composed of microcrystallites. Since the flow rate of metallic particles in the plasma region is of the order of 1 m/s, the present particles changed into nitride particles instantaneously.
An Investigation of the Native Oxide of Aluminum Alloy 7475-T7651 Using XPS, AES, TEM, EELS, GDOES and RBS
Authors: Toh S. K. , McCulloch D. G. , Du Plessis J. , Paterson P. J. K. , Hughes A. E. , Jamieson D. , Rout B. , Long J. M. , Stonham A.
Published: July 2003

The native oxide on the rolled aerospace aluminum alloy 7475-T7651 was characterized using a variety of different techniques, including X-ray Photoelectron Spectrometry (XPS), Auger Electron Spectrometry (AES), Transmission Electron Microscopy (TEM), Electron Energy Loss Spectrometry (EELS), Glow Discharge Optical Emission Spectrometry (GDOES), and Rutherford Backscattered Spectrometry (RBS). All techniques revealed that the native oxide layer is magnesium-rich and is probably a mixture of magnesium and aluminum–magnesium oxides.1 The oxide layer was found to be of nonuniform thickness due to the rolling process involved during the manufacture of this sheet alloy; this complicates analysis using techniques which have poor spatial resolution. Direct thickness measurement from cross-sectional TEM reveals an oxide thickness which varies between 125 and 500 nm. This large variation in thickness was also evident from GDOES and AES depth profiles as well as the RBS data. Both XPS and RBS also show evidence for the presence of heavy metals in the oxide.
Spectral Investigation of Physical Adsorption in Porous Glass
Authors: Dmytruk Andriy , Ovechko Volodymyr
Published: July 2003

An oscillators model of physical adsorption on a silica surface has been built considering the molecular adsorbent-adsorbate complex as two relatively individual parts united by a weak van der Waals interaction. An experimental study of the NIR spectra of ammonia and p-xylene molecules adsorbed in a porous glass has been carried out. Theory and experiment agree well.
Verification Theorems for Optimal Feedback Strategies in Differential Games
Authors: Mirică Ştefan
Published: July 2003

We give complete proofs to the verification theorems announced recently by the author for the "pairs of relatively optimal feedback strategies" of an autonomous differential game. These concepts are considered to describe the possibly optimal solutions of a differential game while the corresponding value functions are used as "instruments" for proving the relative optimality and also as "auxiliary characteristics" of the differential game. The 6 verification theorems in the paper are proved under different regularity assumptions accompanied by suitable differential inequalities verified by the generalized derivatives, mainly of contingent type, of the value function.
A Two-Person Conflict Model in Train Scheduling
Authors: Ghoseiri Keivan , Szidarovszky Ferenc , Asgharpour Mohammad Jawad
Published: July 2003

This paper presents a two-person bargaining model in which railway company and its passenger community are the players in the train-scheduling problem. The fuel consumption cost and the total passenger-time constitute the payoff functions. First, the Pareto frontier is determined using the ∊-constraint method and then conflict resolution is performed using five particular resolution methodologies, namely the non-symmetric Nash solution, the non-symmetric Kalai-Smorodinsky solution, the non-symmetric area monotonic solution, the non-symmetric equal loss solution, and a one-shot solution concept. A numerical example is presented to illustrate the methodology.
From Common Knowledge of Rationality to Backward Induction
Authors: Quesada Antonio
Published: July 2003

With the only assumption that a player knows the strategy he chooses, it is proved in a generalized version of Aumann's (1995) epistemic model that, in a generic game with perfect information, common knowledge of rationality is equivalent to common knowledge of the fact that the backward induction strategy profile is chosen. This result shows that Aumann's backward induction theorem holds without stipulating partition knowledge structures nor presuming that the epistemic operator defines knowledge in the strict sense.
Progressive Current Accounts: Profit-Sharing Interest
Authors: Rambaud Salvador Cruz , del Carmen Valls Martínez María
Published: July 2003

Certain financial investments have different profitabilities according to the invested capital. In particular, there are some bank transactions, such as progressive current accounts, which discriminate nominal rates of interest, depending on the invested sums, that is, transactions whose underlying financial laws are not homogeneous of the first degree with respect to the amounts. More specifically, this discrimination occurs when assigning an equal rate to the capitals C in the same interval ]Ci,Ci+1]. This makes the financial law discontinuous with finite jumps, once the term has been fixed. Of course, it would be convenient, for a group of investors, to join their savings because greater rates of interest can be obtained. The question is how to distribute, in a rational way or with equity, among the individual agents, the interest obtained jointly. Our findings are based on a progressive sharing, using differential calculus.
When will the Range of Prizes in Tournaments Increase in the Noise or in the Number of Players?
Authors: Gerchak Yigal , He Qi-Ming
Published: July 2003

The symmetric equilibrium resulting from the celebrated Tournament model of Lazear and Rosen has a range of compensation between winner and loser which is inversely proportional to E[f(X)], the expectation of the additive noise's density. There seems to be a belief that this functional is always increasing in the noise's variability, which would agree with economic intuition — when output is noisier it should be less worthwhile to work hard. We show that such is not the case for some distributions, and characterize classes where such is or is not the case. When the number of players n grows, winning is more difficult so we would expect the required range of compensation to be larger. That would require that E[f(Y)], where Y = max (X1,…,Xn-1), will decrease in n. We examine the generality of this property. Finally we explore the same issues within a multiplicative model.
Extension of n‐dimensional Euclidean vector space En over ℝ to pseudo‐fuzzy vector space over Fp1(1)
Authors: Wu Kweimei
Published: July 2003

For any two points P = (p(1), p(2), …, p(n)) and Q = (q(1), q(2), …, q(n)) of ℝn, we define the crisp
vector . Then we obtain an n‐dimensional vector space . Further, we extend the crisp vector into the fuzzy vector on
fuzzy sets of ℝn. Let be any two fuzzy sets on ℝn and define the fuzzy vector , then we have a pseudo‐fuzzy vector space.
The conjugation operator on Aq(G)
Authors: Gupta Sanjiv Kumar
Published: July 2003

Let q > 2. We prove that the conjugation operator H does not extend to a bounded operator on the space of integrable functions defined on any compact abelian group with the Fourier transform in
lq.
The Baum‐Connes conjecture, noncommutative Poincaré duality,and the boundary of the free group
Authors: Emerson Heath
Published: July 2003

For every hyperbolic group Γ with Gromov boundary ∂Γ, one can form the cross product C∗‐algebra C(∂Γ)⋊Γ. For each such algebra, we construct a canonical K‐homology class. This class induces a Poincaré duality map K∗(C(∂Γ)⋊Γ) → K∗+1(C(∂Γ)⋊Γ). We show that this map is an isomorphism in the case of Γ = 𝔽2, the free group on two generators. We point out a direct connection between our constructions and the Baum‐Connes conjecture and eventually use the latter to deduce our result.
On m‐accretive Schrödinger‐type operators with singular potentials on manifolds of bounded geometry
Authors: Milatovic Ognjen
Published: July 2003

We consider a Schrödinger‐type differential expression ∇∗ ∇+V, where ∇ is a C∞‐bounded Hermitian connection on a Hermitian vector bundle E of bounded geometry over a manifold of bounded geometry (M, g) with positive C∞‐bounded measure dμ, and V is a locally integrable linear bundle endomorphism. We define a realization of ∇∗ ∇+V in L2(E) and give a sufficient condition for its m‐accretiveness. The proof essentially follows the scheme of T. Kato, but it requires the use of a more general version of Kato′s inequality for Bochner Laplacian operator as well as a result on the positivity of solution to a certain differential equation on M.
Existence and global stability of positive periodic solutions of a discrete delay competition system
Authors: Huo Hai-Feng , Li Wan-Tong
Published: July 2003

The existence and the global stability of positive periodic solutions of a discrete competition model is studied. The model incorporates time delays and allows for a fluctuating environment. By means of some standard procedures of the topological degree method and the construction of a suitable Lyapunov function, sufficient conditions are obtained to ensure the existence and the global stability of positive periodic solutions of the above systems.
Techniques of the differential subordination for domains bounded by conic sections
Authors: Kanas Stanisława
Published: July 2003

We solve the problem of finding the largest domain D for which, under given ψ and q, the differential subordination ψ(p(z), zp′(z)) ∈ D⇒p(z)≺q(z), where D and q(𝒰) are regions bounded by conic sections, is satisfied. The shape of the domain D is described by the shape of q(𝒰). Also, we find the best dominant of the differential subordination p(z) + (zp′(z)/(βp(z) + γ))≺pk(z), when the function pk(k ∈ [0, ∞)) maps the unit disk onto a conical domain contained in a right half‐plane. Various applications in the theory of univalent functions are also given.
DP1 and completely continuous operators
Authors: Bator Elizabeth M. , Slavens Dawn R.
Published: July 2003

W. Freedman introduced an alternate to the
Dunford‐Pettis property, called the DP1 property,
in 1997. He showed that for 1 ≤ p < ∞,
has the DP1 property if and only if each Xα does. This is not the case for . In
fact, we show that has the DP1 property if and only if it has
the Dunford‐Pettis property. A similar result also
holds for vector‐valued continuous function spaces.
Immune reconstitution to cytomegalovirus after allogeneic hematopoietic stem cell transplantation: impact of host factors, drug therapy, and subclinical reactivation
Authors: Hakki Morgan , Riddell Stanley R. , Storek Jan , Carter Rachel A. , Stevens-Ayers Terry , Sudour Patrick , White Kristen , Corey Lawrence , Boeckh Michael
Published: July 2003

Reconstitution of cellular immunity by 3 months after hematopoietic stem cell transplantation (HSCT) is a critical determinant of the long-term success of the transplantation. We analyzed the factors affecting recovery of cytomegalovirus (CMV)–specific CD4+ and CD8+ function at 3 months after HSCT by univariate and multivariable analyses including source of stem cells (bone marrow vs peripheral blood stem cells [PBSCs]), age, sex, graft-versus-host disease (GVHD), steroid use, conditioning regimens, ganciclovir use, HLA matching, circulating CMV antigenemia, absolute CD4+ and CD8+ counts, and donor CMV serology. High-dose steroids and CD4+ count less than 100 × 109/L were significant predictors of impaired CD4+ functional recovery in the multivariable analysis. High-dose steroids, bone marrow as a source of stem cells, and CD8+ count less than 50 × 109/L were associated with impaired CD8+ function in the multivariable analysis. Steroids were found to impair both CD4+ and CD8+ function in a dose-dependent manner. In the absence of high-dose steroids, low-level subclinical CMV antigenemia was found to stimulate both CD4+ and CD8+ functional recovery in recipients of ganciclovir prophylaxis. There was no difference in immune reconstitution between those who received prophylactic ganciclovir versus antigenemia-guided pre-emptive therapy. Thus, absolute CD4+ and CD8+ counts less than 100 × 109/L and 50 × 109/L, respectively; bone marrow as the source of stem cells; and high-dose steroid use all predict delayed recovery of functional T-cell immunity at 3 months after transplantation. Subclinical CMV reactivation while on ganciclovir appears to be a potent stimulator of T-cell function. These findings have implications for vaccination and adoptive-immunotherapy strategies in this population.
Hematopoietic stem cell transplantation for progressive multiple sclerosis: failure of a total body irradiation–based conditioning regimen to prevent disease progression in patients with high disability scores
Authors: Burt Richard K. , Cohen Bruce A. , Russell Eric , Spero Kenneth , Joshi Akash , Oyama Yu , Karpus William J. , Luo Kehuan , Jovanovic Borko , Traynor Ann , Karlin Karyn , Stefoski Dusan , Burns William H.
Published: July 2003

There were 21 patients with rapidly progressive multiple sclerosis (MS) treated on a phase 1/2 study of intense immune suppressive therapy and autologous hematopoietic stem cell (HSC) support with no 1-year mortality. Following transplantation, one patient had a confirmed acute attack of MS. Neurologic progression defined by the expanded disability status scale (EDSS) did not increase in disability by 1.0 or more steps in any of 9 patients with a pretransplantation EDSS of 6.0 or less. In 8 of 12 patients with high pretransplantation disability scores (EDSS > 6.0), progressive neurologic disability as defined by at least a 1-point increase in the EDSS has occurred and was manifested as gradual neurologic deterioration. There were 2 patients with a pretransplantation EDSS of 7.0 and 8.0 who died from complications of progressive disease at 13 and 18 months following treatment. Our experience suggests that intense immune suppression using a total body irradiation (TBI)-based regimen and hematopoietic stem cell transplantation (HSCT) are not effective for patients with progressive disease and high pretransplantation disability scores. Further studies are necessary to determine the role of intense immune suppressive therapy and HSC support in ambulatory patients with less accumulated disability and more inflammatory disease activity. Specifically, more patients and longer follow-up would be required in patients with an EDSS of 6.0 or less before drawing conclusions on this subgroup. (Blood. 2003;102:2373-2378)
Rituximab therapy for HIV-associated Castleman disease
Authors: Marcelin Anne-Geneviève , Aaron Laurent , Mateus Christine , Gyan Emmanuel , Gorin Isabelle , Viard Jean-Paul , Calvez Vincent , Dupin Nicolas
Published: July 2003

To assess the clinical benefit of rituximab for HIV-associated Castleman disease, 5 patients infected with HIV with histologic-proven Castleman disease were prospectively enrolled to receive 4 infusions of rituximab. Clinical and biologic parameters (C-reactive protein, CD19 cell count, Kaposi sarcoma–associated herpesvirus [KSHV] viral load in peripheral blood mononuclear cells) were assessed before and at different time points following rituximab infusions. Two patients died very quickly after the beginning of rituximab therapy with no effect on both KSHV viral load and CD19 cell count. Three of 5 patients were considered in complete remission with no more clinical symptoms related to Castleman disease with a follow-up of 4 to 14 months. In 2 cases, clinical remission correlated with a dramatic decrease of KSHV viral load and C-reactive protein levels and a transitory but sharp decrease of CD19 cell count. In 2 responders, we observed an aggravation of Kaposi sarcoma. Our preliminary results suggest that rituximab may be effective in controlling Castleman disease in a subset of patients, although it may exacerbate concomitant Kaposi sarcoma.
Effect of circulating blasts at time of complete remission on subsequent relapse-free survival time in newly diagnosed AML
Authors: Estey Elihu H. , Thall Peter F. , Wang Xuemei , Verstovsek Srdan , Cortes Jorge , Kantarjian Hagop M.
Published: July 2003

Standardized criteria for complete remission (CR) in acute myeloblastic leukemia (AML) require the absence of peripheral blood blasts (PBBs). However, MD Anderson (MDA) criteria for CR (CR-MDA), although including the other requirements for CR, have not included the PBB count. We exploit this difference to assess the effect of PBBs at the time of CR-MDA on relapse-free survival (RFS) time. Eighty percent of the 533 patients with newly diagnosed AML or refractory anemia with excess of blasts (RAEB) entering CR-MDA from 1995 to 2000 had no PBBs at time of CR-MDA. Ninety-three percent of the remaining patients, who thus had CR-MDA but not standard CR, had 1% to 5% PBBs at this time. Multivariate analyses, using both conventional and Bayesian approaches, indicated that PBBs had no effect on RFS. For all patients and for the subgroups given and not given granulocyte colony-stimulating factor (G-CSF), the 95% credible interval for the relative risk of failure in the PBB group was nearly centered at 1.0. Thus, our data do not support use of PBBs in defining CR in newly diagnosed AML.
Eco-friendly and Highly Chemoselective 1,3-Oxathio- and 1,3-Dithioacetalization of Aldehydes Using Ionic Liquids
Authors: Yadav J S , Reddy B V S , Kondaji G
Published: July 2003

Room temperature ionic liquids have been employed for the first time as novel and recyclable reaction media for the chemoselective conversion of aldehydes into their corresponding 1,3-oxathio- and dithioacetal derivatives in excellent yields under mild and neutral conditions. A wide range of functional and protecting groups such as TBDMS, PMB, THP, MOM, benzyl, propargyl ethers, acetonides, carbamates and esters are survived under these reaction conditions. The recovered activated ionic liquids can be recycled for four to five subsequent runs with consistency in activity.
Synthesis of Novel Carbazole Dendrimers Having a Metal Coordination Site
Authors: Kimoto Atsushi , Cho Jun-Sang , Higuchi Masayoshi , Yamamoto Kimihisa
Published: July 2003

We have synthesized novel carbazole dendrimers via cyclotrimerization. This synthetic procedure to prepare the dendrimers, especially with a higher generation, via the cyclization reaction was found to be an extremely effective method. These dendrimers have the ability to assemble metal ions such as Sn2+ and Eu3+, resulting in a change in its fluorescence property.
New One-pot Cross-coupling Reaction between Grignard Reagents and Alkoxymethyldiphenylphosphonium Iodides in situ-Formed from Alcohols, Chlorodiphenylphosphine and Iodomethane
Authors: Shintou Taichi , Kikuchi Wataru , Mukaiyama Teruaki
Published: July 2003

A new one-pot cross-coupling reaction between Grignard reagents and alkoxymethyldiphenylphosphonium iodides, which were in situ-formed from nBuLi-treated alcohols, chlorodiphenylphosphine and iodomethane, proceeded smoothly to afford the corresponding coupling products in good to high yields.
A Remarkable Isotope Effect on the Photochromism of trans-Biindenylidenedione in the Solid State
Authors: Tanaka Koichi , Yamamoto Yohei , Takano Hideyuki , Caira Mino R
Published: July 2003

A remarkable deuterium isotope effect on the photochromism of 3,3′-diaryl-3H,3′H-[2,2′]biindenylidene-1,1′-dione (2) in the solid state has been found. The yellow crystals of 2 and 2-d2 were immediately changed to reddish purple crystals upon photoirradiation in the solid state. The reddish purple crystals of 2-d2 returned back to the original yellow crystals under dark for 72 h, whereas that of 2 faded within 2 h.
Preparation and Characterization of 6-Carboxychitosan
Authors: Zhou Yongguo , Yang Yuedong , Wang Dongjun , Liu Xiaomin
Published: July 2003

The hydroxymethyl group of 2-amino-2-deoxy-d-glucose unit in chitosan was selectively oxidized to carboxyl group with NO2 to form amphoteric chitosan by one step so as to give chitosan a new bioactivity. The structure and properties of amphoteric chitosan are discussed.
Detection of A/G Single Nucleotide Alteration in RNA Using Base-discriminating Fluorescent Oligodeoxynucleotides
Authors: Okamoto Akimitsu , Tainaka Kazuki , Saito Isao
Published: July 2003

We report the fluorescence properties of oligodeoxynucleotides (ODNs) containing a base-discriminating fluorescent nucleoside, benzopyridopyrimidine (BPP), in hybridizing with RNAs possessing different bases opposite BPP. BPP-containing ODN selectively exhibited a strong fluorescence when the RNA base opposite BPP was A, whereas the fluorescence of BPP-containing ODN hybridized with RNA possessing G opposite BPP was very weak. BPP acts as a good base-discriminating fluorescent nucleoside for A/G single base alteration of RNA.
Nanosilver Fabrication under the Control of Ligands Containing Pyridyl Group in Solution Phase with Photoreduction Method
Authors: Xie Zhen , Wang Zhiyong , Ke Yanxiong , Zha Zhenggen , Jiang Chao
Published: July 2003

Nanosilver was prepared by photoreduction method and the size and shape of the nanosilver can be easilly controlled by changing the organic capping reagent such as pyridine, nicotinic acid, 2,2′-dipyridylamine and 2,2′-bipyridine. Using different capping reagents, different shapes of nanosilvers, such as nanoribbon, nanotriangle or nanowire, can be obtained under mild condition.
Magnetic Composite Nanoparticle of Au/γ-Fe2O3 Synthesized by Gamma-Ray Irradiation
Authors: Seino Satoshi , Kinoshita Takuya , Otome Yohei , Okitsu Kenji , Nakagawa Takashi , Yamamoto Takao A
Published: July 2003

Magnetic composite nanoparticle of Au/γ-Fe2O3 was synthesized in an aqueous phase using gamma-ray. Connection between gold and γ-Fe2O3 was confirmed by the magnetic separation technique. TEM observation shows that 5-nm gold particles were dispersed on 20-nm γ-Fe2O3 particles. The nanoparticles adsorbed a water-soluble mercaptan, glutathione, and was manipulated by an external magnetic field.
Self-assembled Dendrimer-bound Pd(II) Complexes via Acid-base Interactions and their Catalysis for Allylic Amination
Authors: Ooe Masahiko , Murata Makoto , Takahama Atsushi , Mizugaki Tomoo , Ebitani Kohki , Kaneda Kiyotomi
Published: July 2003

The Pd complexes were noncovalently attached on the periphery of poly(propyleneimine) dendrimers based on acid-base interactions. The dendritic Pd complexes were found to possess catalytic activities for allylic amination, and to be able to mimick the catalytic activity of the analogous monomeric Pd complex catalyst.
Systematic Synthesis of Porphyrin Dimers Linked by Conjugated Oligoacetylene Bridges
Authors: Nakamura Kazuya , Fujimoto Tatsuhiko , Takara Satoshi , Sugiura Ken-ichi , Miyasaka Hitoshi , Ishii Tomohiko , Yamashita Masahiro , Sakata Yoshiteru
Published: July 2003

A series of α,ω-bis(meso-porphyrinyl)oligoacetylenes were systematically prepared. The exciton interaction between the porphyrins gradually decreased with increasing number of acetylenes, whereas the interaction between the porphyrin and the oligoacetylene unit appeared.
Lithium Acetate Catalyzed Aldol Reaction between Aldehyde and Trimethylsilyl Enolate in a Dimethylformamide–H2O Solvent
Authors: Nakagawa Takashi , Fujisawa Hidehiko , Mukaiyama Teruaki
Published: July 2003

Lithium acetate catalyzed aldol reaction between trimethylsilyl enolates and aldehydes in a DMF–H2O (50:1) solvent proceeded smoothly to afford the corresponding aldols in good to high yields. It is noted that trimethylsilyl enolates derived from carboxylic esters behaved as excellent nucleophiles in the above reaction.
Construction of 2D Superlattices of Gold Nanoparticles at an Air/Water Interface Based on Hydrogen-Bonding Networks
Authors: Yao Hiroshi , Kojima Hiroyuki , Sato Seiichi , Kimura Keisaku
Published: July 2003

Two-dimensional (2D) superlattices of mercaptosuccinic acid-modified gold nanoparticles were constructed at an air/water interface in the presence of 4-pyridinecarboxylic acid (PyC). Hydrogen-bonding interaction caused the incorporation of PyC into the surface-functionalized gold nanoparticles, suggesting that the interparticle spacing in the superlattices is controllable with an intercalating molecule.
Determination of Fundamental Harmonic-to-secondary Harmonic Ratio of Longitudinal Magnetization Change in Triarylmethyl or Nitroxide Radical Aqueous Solution Caused by ESR at 280 MHz for Nondestructive Oximetry
Authors: Yokoyama Hidekatsu , Sato Toshiyuki , Fukui Kouichi , Itoh Osamu , Ohya Hiroaki , Akatsuka Takao
Published: July 2003

In a longitudinally detected ESR (LODESR) method, longitudinal (i.e., parallel to the static magnetic field) magnetization changes caused by on/off modulated ESR irradiation are observed. In this study, LODESR oximetry was newly designed so that a detection frequency was fixed and on/off modulation frequencies were varied. LODESR signal intensities when the modulation frequency was equal to the detecting frequency (fundamental harmonic detection) and when it was half the value of the detection frequency (secondary harmonic detection) were simulated at a constant detection frequency. Fundamental harmonic-to-secondary harmonic ratios (FSRs) were calculated by dividing the former by the latter. This simulation showed that FSR increased with the reciprocal of longitudinal relaxation time. LODESR measurements of phantoms containing triarylmethyl or a nitroxide radical that had been dissolved in 10 cm3 of a physiological saline solution and various concentrations of oxygen were made at an ESR frequency of 280 MHz. It was found that the FSRs of both phantoms increased as the concentration of oxygen increased.
Stereochemical Interactions in Ammonium Dications, Hypervalent Diammonium Cation-Radicals and Ammonium Radicals. A B3-MP2 Computational Study
Authors: Tureček František
Published: July 2003

Hypervalent ammonium radicals and cation-radicals derived from cis and trans-cyclopentane-1,2-diamine have been studied computationally with the goal of elucidating intramolecular interactions between the ammonium and amine functional groups in a conformationally rigid model system. Hypervalent cis and trans-cyclopentane-1-ammonium-2-amine radicals are only marginally stable against dissociation by loss of an ammonium hydrogen atom and ammonia. The radicals are predicted to exhibit very similar dissociations originating from the ground and excited electronic states. The dissociation and transition state energies in bifunctional hypervalent ammonium radicals are analogous to those reported previously for monofunctional ammonium radicals. Stereochemical effects are predicted to occur in the formation and dissociations of hypervalent cis and trans-cyclopentane-1,2-diammonium cation-radicals. The cis-isomer is calculated to undergo very facile elimination of dihydrogen resulting from a dipolar H+….H− interaction between the ammonium groups. The trans-isomer is predicted to spontaneously dissociate to a complex of cyclopentene cation-radical and two ammonia molecules.
Inorganic Luminescent Materials: 100 Years of Research and Application
Authors: Feldmann C. , Jüstel T. , Ronda C.R. , Schmidt P.J.
Published: July 2003

Up until approximately 80 years ago, only black‐body radiation (including natural sources) was available to illuminate our environment. To realise state‐of‐the‐art lamps, TV sets, monitors, and medical scanners, took an enormous scientific and technical effort. Inorganic luminescent materials are key components, which were, are, and will be prerequisite to the functionality and success of many lighting and display systems. In this Highlight, a hundred years of inorganic luminescent material research are reviewed.
Single‐Mode Microwave Synthesis in Organic Materials Chemistry
Authors: Barlow S. , Marder S.R.
Published: July 2003

Some applications of microwave synthesis in organic materials chemistry are highlighted in this contribution, including applications to Knoevanagel reactions used in the synthesis of donor‐π‐acceptor NLO chromophores, and to Ni0‐mediated coupling reactions in the synthesis of poly(fluorene)s.
Liquid‐Crystalline Phase Behavior in a Zwitterionic Tetraazapentacene
Authors: Riley A.E. , Mitchell G.W. , Koutentis P.A. , Bendikov M. , Kaszynki P. , Wudl F. , Tolbert S.H.
Published: July 2003

A 5,7‐dioctadecylquinoxalinophenazine zwitterion 1 has been investigated to determine its thermal phase behavior. A combination of differential scanning calorimetry (DSC), variable temperature low‐ and high‐angle X‐ray diffraction (XRD), and deuterium solid‐state NMR spectroscopy were used to characterize the different phases of the tetraazapentacene 1. This molecule is found to exist in a variety of crystalline solid phases between room temperature and 167 °C, with different room‐temperature phases resulting from crystallization from solution compared with cooling from the melt. Interestingly, the molecule exhibits liquid‐crystalline behavior at high temperatures, between 167 °C and 186 °C, above which it becomes an isotropic fluid. The presence of liquid‐crystalline behavior in a zwitterionic system opens up the potential for the use of these or related molecules in optoelectronic switching.
The Fabrication and Characterization of Carbon Aerogels by Gelation and Supercritical Drying in Isopropanol
Authors: Fu R. , Zheng B. , Liu J. , Dresselhaus M.S. , Dresselhaus G. , Satcher J.H. , Baumann T.F.
Published: July 2003

We report a new method for the fabrication of carbon aerogels. Resorcinol and furfural were polymerized in isopropanol using HCl as a catalyst and the resulting alcogels were then dried directly using supercritical isopropanol, followed by carbonization under a nitrogen atmosphere. The carbon aerogels can be prepared over a range of densities (0.148–0.746 g/cm3), depending on the gelation temperature and the mass content of the reactants. The textural and transport properties of the aerogels materials were characterized by nitrogen adsorption/desorption analysis, high‐resolution transmission electron microscopy (HRTEM), magnetic susceptibility, and resistivity measurements. TEM observations show that the carbon aerogels are composed of interconnected nanoparticles with diameters ranging from 20 to 30 nm. All of the aerogel samples exhibit high Brunauer– Emmett–Teller (BET) surface areas in the range of 557–656 m2/g. The carbon aerogels produced by this new method have similar transport properties to those of carbon aerogels prepared by the traditional method.
Synthesis of Indium and Indium Oxide Nanoparticles from Indium Cyclopentadienyl Precursor and Their Application for Gas Sensing
Authors: Soulantica K. , Erades L. , Sauvan M. , Senocq F. , Maisonnat A. , Chaudret B.
Published: July 2003

Decomposition of the organometallic precursor [In(η5‐C5H5)] in toluene in the presence of methanol (8 vol.‐%) at room temperature leads to the immediate formation of aggregates of indium nanoparticles of 15 ± 2 nm mean diameter. The aggregates are roughly spherical with a mean size of 400 ± 40 nm. The particles were characterized by means of transmission electron and high‐resolution transmission electron microscopies (TEM and HRTEM), and X‐ray diffraction (XRD) studies indicate that the powder consists of the tetragonal phase of indium. The thermal oxidation in air of these nanoparticles yields well‐crystallized nanoparticles of In2O3 with unchanged morphology (aggregates of nanoparticles of 16.6 ± 2 nm mean diameter with aggregate mean size of 400 ± 40 nm) and without any sign of coalescence. XRD pattern shows that the powder consists of the cubic phase of In2O3. The electrical conductivity measurements demonstrate that this material is highly sensitive to an oxidizing gas such as nitrogen dioxide and barely sensitive to a reducing gas such as carbon monoxide. Its association with SnO2‐based sensors allows the selective detection of carbon monoxide (30 ppm) and sub‐ppm amounts of nitrogen dioxide (400 ppb) in a mixture at 21 °C and at a relative humidity of 60 %.
Conversion of Fly Ash Cenosphere to Hollow Microspheres with Zeolite/Mullite Composite Shells
Authors: Wang D.J. , Zhang Y.H. , Dong A.G. , Tang Y. , Wang Y.J. , Xia J.C. , Ren N.
Published: July 2003

A seed‐induced in‐situ hydrothermal conversion technique is proposed to prepare novel hollow microspheres with zeolite/mullite composite shells from fly ash cenosphere (FAC), a solid waste with a hollow structure from coal power stations. Two groups of hollow microspheres were prepared, one with zeolite FAU/mullite composite shells and the other with zeolite LTA/mullite composite shells. The FAC in this study plays dual roles as both the template cores and the aluminosilicate nutrition contributor. The final products inherit the hollow spherical morphology of FAC and possessed bilayered shells, the outer dense shell of zeolite crystals and the inner porous shell of mullite. Such hollow zeolitic materials are expected to have many advantages in applications such as catalysis, adsorption, separation, and as releasing capsules.