bluuebunny/crossref_metadata_2025 huggingface dataset:
Photocatalytic Cleavage of Single TiO2/DNA Nanoconjugates
Authors: Tachikawa Takashi , Asanoi Yoshiaki , Kawai Kiyohiko , Tojo Sachiko , Sugimoto Akira , Fujitsuka Mamoru , Majima Tetsuro
Published: November 2007

TiO2/DNA nanoconjugates were successfully fabricated by using the catechol moiety as a binding functional group, which was confirmed by steady‐state absorption and fluorescence spectroscopies. Upon UV irradiation, the photocatalytic cleavage of the TiO2/DNA nanoconjugates was observed at the single‐molecule level by using wide‐field fluorescence microscopy. The decrease in the number of conjugates, which was estimated from the luminescent spots due to semiconductor quantum dots modified at the DNA strand, was significantly inhibited by a single A/C mismatch in the DNA sequences. This result strongly suggests that the migration of holes, which are injected from the photoexcited TiO2 into the DNA, through the DNA bases plays an important role in the photocatalytic cleavage of the conjugates. The influences of the photogenerated reactive oxygen species (ROS) on the cleavage efficiency were also examined. According to the experimental results, it was concluded that oxidation of the catechol moiety and/or the DNA damage are key reactions in this process.
Macrophage attenuation of neuronal excitability: Implications for pathogenesis of neurodegenerative disorders
Authors: Wang Wenwei , Hu Dehui , Xiong Huangui
Published: November 2007

Brain macrophages (and microglia) play a crucial role in central nervous system immune and inflammatory responses. They are also critical cells in the pathogenesis of neurodegenerative disorders. To understand how macrophages cause neural cell dysfunction, we investigated the effects of mouse bone marrow‐derived macrophages (BMDMs) on rat cortical neuronal physiology in a BMDM‐neuronal co‐culture system using whole‐cell patch clamp techniques. When co‐cultured with neuronal cells, BMDMs hyperpolarized the neuronal membrane and attenuated both spontaneous and electrically evoked firings through a decrease in membrane input resistance. The average duration of evoked action potentials (APs) and the latency to fire the APs, in response to a constant depolarizing current injection, were significantly increased by BMDMs. These results indicate that BMDMs attenuate neuronal excitability. Further investigation revealed that BMDMs hyperpolarize neuronal membranes by enhancing neuronal delayed rectifier potassium current (IK), which was blocked by tetraethylammonium. This BMDM‐induced attenuation on neuronal excitability may contribute to the pathogenesis of neuronal dysfunction and damage as seen in neurodegenerative disorders. © 2007 Wiley‐Liss, Inc.
Prevalence of clinically significant depressive symptoms in an epidemiologic sample of community‐dwelling elders with milder forms of cognitive impairment in Hong Kong SAR
Authors: Chan Sandra S. M. , Lam Linda C. W. , Tam Cindy W. C. , Lui Victor W. C. , Chan W. C. , Wong Sunny , Wong Ada , Tham M. K. , Ho K. S. , Chan W. M. , Chiu Helen F. K.
Published: November 2007

Background

Depression and cognitive impairment in later‐life have great bearings on public health. The two conditions often co‐occur and have mutual implications on short‐term risk and long‐term prognosis.

Method

A two‐phase epidemiologic survey on the prevalence of dementia in elders aged 60 and over was conducted in Hong Kong in 2005–2006. In the first phase, 6,100 randomly selected community dwelling elders were assessed with Cantonese version of Mini‐Mental State Examination (C‐MMSE) and Abbreviated Memory Inventory for Chinese (AMIC). Two thousand and seventy‐three subjects were screened positive and invited for second phase cognitive and psychiatric assessment. 35.5% of screen‐positive subjects participated in Phase 2 assessment conducted by psychiatrists for diagnosis of dementia. Severity of dementia was determined using Clinical Dementia Rating Scale (CDR). Cornell Scale for Depression in Dementia (CSDD) and a structured bedside cognitive battery were also administered to each subject.

Results

1.7% of subjects with CDR 0.5 and 5.9% of subjects with CDR 1 had clinically significant depressive symptoms (>/ = 8 on CSDD). Score on CSDD correlated positively with duration of cognitive symptoms, scores on CIRS and CMMSE in linear regression model. In a logistic regression model, male gender, duration of cognitive symptoms, CIRS and CMMSE was associated with increased risk for clinically significant depressive symptoms.

Conclusions

In our sample, milder forms of cognitive impairment were associated with increased risk for depression in the presence of other risk factors such as male gender, higher physical illness burden and longer duration of cognitive symptoms. Copyright © 2007 John Wiley & Sons, Ltd.
Hepatitis B virus infection initiates with a large surface protein–dependent binding to heparan sulfate proteoglycans
Authors: Schulze Andreas , Gripon Philippe , Urban Stephan
Published: November 2007

Contrary to many other viruses, the initial steps of the hepatitis B virus (HBV) infection, including attachment to hepatocytes, specific receptor interactions, and membrane fusion, are unsolved. Using HepaRG cells as an

in vitro

cell culture system, we here report that HBV entry into hepatocytes depends on the interaction with the glycosaminoglycan (GAG) side chains of cell-surface–associated heparan sulfate proteoglycans. Binding to GAGs requires the integrity of the pre-S domain as a part of the large (L-) viral envelope protein. HBV infection was abrogated by incubation of virions with heparin, but not the structurally related GAGs chondroitin sulfate A, B, and C. Infection was also abolished by suramin, a known inhibitor of duck hepatitis B virus infection or highly sulfated dextran sulfate. Polycationic substances such as poly-l-lysine, polybrene, and protamine also prevented infection, however, by addressing cellular components. Enzymatic removal of defined acidic carbohydrate structures from the cell surface using heparinase I/III or the obstruction of GAG synthesis by sodium chlorate inhibited HBV infection of HepaRG cells and, moreover, led to a reduction of HBV cell surface binding sites. The biochemical analysis showed selective binding of L-protein–enriched viral particles (virions or filaments) to heparin. GAG-dependent binding of HBV was improved by polyethylene glycol, a substance that specifically enhances HBV infection.

Conclusion:

HBV infection requires the initial attachment to the carbohydrate side chains of hepatocyte-associated heparan sulfate proteoglycans as attachment receptors. This interaction initializes the multistep entry process of HBV and cannot be bypassed by alternative routes. (Hepatology 2007;46:1759–1768.)
The generalized Pareto sum
Authors: Nadarajah Saralees , Kotz Samuel
Published: November 2007

The generalized Pareto distribution has received much popularity as models for extreme events in hydrological sciences. In this note, the important problem of the sum of two independent generalized Pareto random variables is considered. Exact analytical expressions for the probability distribution of the sum are derived and a detailed application to drought data from Nebraska is provided. Copyright © 2007 John Wiley & Sons, Ltd.
A Bayesian reconstruction method for micro‐rotation imaging in light microscopy
Authors: Laksameethanasan Danai , Brandt Sami S. , Engelhardt Peter , Renaud Olivier , Shorte Spencer L.
Published: November 2007

The authors present a three‐dimensional (3D) reconstruction algorithm and reconstruction‐based deblurring method for light microscopy using a micro‐rotation device. In contrast to conventional 3D optical imaging where the focal plane is shifted along the optical axis, micro‐rotation imaging employs dielectric fields to rotate the object inside a fixed optical set‐up. To address this entirely new 3D‐imaging modality, the authors present a reconstruction algorithm based on Bayesian inversion theory and use the total variation function as a structure prior. The spectral properties of the reconstruction by simulations that illustrate the strengths and the weaknesses of the micro‐rotation approach, compared with conventional 3D optical imaging, were studied. The reconstruction from real data sets shows that this method is promising for 3D reconstruction and offers itself as a deblurring method using a reconstruction‐based procedure for removing out‐of‐focus light from the micro‐rotation image series. Microsc. Res. Tech., 2008. © 2007 Wiley‐Liss, Inc.
Visualization of shell matrix proteins in hemocytes and tissues of the Eastern oyster, Crassostrea virginica
Authors: Johnstone Mary B. , Ellis Steve , Mount Andrew S.
Published: November 2007

The tissues of the oyster were examined for the presence of shell matrix proteins (SMPs) using a combination of Western, proteomic, and epi‐fluorescent microscopy techniques. SMP, including 48 and 55 kDa phosphoproteins, was detected in the epithelial cells of mantle, gill, heart, and adductor muscle and linings of arteries and veins. The 48 kDa SMP circulates continuously within the hemolymph, and is present in the immune system hemocytes. It appears to be secreted from hemocytes on induction of shell repair. We suggest that the 48 and 55 kDa proteins are multifunctional and bridge the process of soft tissue repair and shell formation by mediating cellular activities during immune response as well as interacting with the mineral phase during deposition. J. Exp. Zool. (Mol. Dev. Evol.) 310B:227–239, 2008. © 2007 Wiley‐Liss, Inc.
Expansion of Selection Criteria for Patients with Hepatocellular Carcinoma in Living Donor Liver Transplantation
Authors: Ito Takashi , Takada Yasutsugu , Ueda Mikiko , Haga Hironori , Maetani Yoji , Oike Fumitaka , Ogawa Kohei , Sakamoto Seisuke , Ogura Yasuhiro , Egawa Hiroto , Tanaka Koichi , Uemoto Shinji
Published: November 2007

In the present study, the results of living donor liver transplantation (LDLT) for 125 hepatocellular carcinoma (HCC) patients were analyzed to determine optimal criteria exceeding the Milan criteria (MC) but still with predictably good outcomes. On the basis of pretransplant imaging studies, 70 patients met the MC, and 55 patients did not. Patients who exceeded the MC but presented with ≤10 tumors all ≤5 cm in diameter (n = 30) displayed 5-year recurrence rates (7.3%) similar to those of patients within the MC (9.7%, P = 0.8787). According to the results of multivariate analysis of risk factors for recurrence among preoperative tumor variables, we have defined the new criteria, namely ≤10 tumors all ≤5 cm in diameter and protein induced by vitamin K absence or antagonist-II (PIVKA-II) ≤400 mAU/mL. The 78 patients who met the new criteria showed significantly lower 5-year recurrence rates (4.9%) than the 40 patients who exceeded them (60.5%, P < 0.0001). Similarly, 5-year survival rates significantly differed between these groups (86.7% versus 34.4%, respectively; P < 0.0001). In conclusion, selection criteria for patients with HCC undergoing LDLT may be safely extended to ≤10 tumors all ≤5 cm in diameter and PIVKA-II ≤400 mAU/mL with acceptable outcomes. Liver Transpl 13: 1637–1644, 2007. © 2007 AASLD.
Presentation of an Acquired Urea Cycle Disorder Post Liver Transplantation
Authors: Ghabril Marwan , Nguyen Justin , Kramer David , Genco Trina , Mai Martin , Rosser Barry G.
Published: November 2007

The liver's role as the largest organ of metabolism and the unique and often critical function of liver-specific enzyme pathways imply a greater risk to the recipient of acquiring a donor metabolic disease with liver transplants versus other solid organ transplants. With clinical consequences rarely reported, the frequency of solid organ transplant transfer of metabolic disease is not known. Ornithine transcarbamylase deficiency (OTCD), although rare, is the most common of the urea cycle disorders (UCDs). Because of phenotypic heterogeneity, OTCD may go undiagnosed into adulthood. With over 5000 liver transplant procedures annually in the United States, the likelihood of unknowingly transmitting OTCD through liver transplantation is very low. We describe the clinical course of a liver transplant recipient presenting with acute hyperammonemia and encephalopathy after receiving a liver graft form a donor with unrecognized OTCD. Liver Transpl 13: 1714–1716, 2007. © 2007 AASLD.
Intravenous Interferon During the Anhepatic Phase of Liver Retransplantation and Prevention of Recurrence of Cholestatic Hepatitis C Virus
Authors: Kwo Paul Y. , Saxena Romil , Cummings Oscar W. , Tector Joseph A.
Published: November 2007

Cholestatic hepatitis C virus (HCV) infection post orthotopic liver transplantation is associated with a poor prognosis. We describe 2 patients who received interferon and ribavirin for cholestatic HCV infection with clearance of HCV RNA from the serum. Both developed signs of graft failure necessitating repeat orthotopic liver transplantation, and at surgery, interferon was administered during the anhepatic phase to prevent graft reinfection. Both patients are doing well with no evidence of recurrent viremia at 36 and 24 months of follow-up after repeat transplantation, respectively. Our results suggest that in those with cholestatic HCV infection, repeat transplantation after viral clearance is feasible and can occur without reinfection of the graft, challenging the current practice of denying retransplantation for patients with cholestatic HCV. The role of anhepatic administration of interferon deserves further examination, and this combination may provide a solution in a subset of patients with an otherwise poor prognosis. Liver Transpl 13:1710–1713, 2007. © 2007 AASLD.
A comparison of the mini mental state exam to the montreal cognitive assessment in identifying cognitive deficits in Parkinson's disease
Authors: Zadikoff Cindy , Fox Susan H. , Tang‐Wai David F. , Thomsen Teri , de Bie Rob M.A. , Wadia Pettarusup , Miyasaki Janis , Duff‐Canning Sarah , Lang Anthony E. , Marras Connie
Published: November 2007

Dementia is an important and increasingly recognized problem in Parkinson's disease (PD). The mini‐mental state examination (MMSE) often fails to detect early cognitive decline. The Montreal cognitive assessment (MoCA) is a brief tool developed to detect mild cognitive impairment that assesses a broader range of domains frequently affected in PD. The scores on the MMSE and the MoCA were compared in 88 patients with PD. A pronounced ceiling effect was observed with the MMSE but not with the MoCA. The range and standard deviation of scores was larger with the MoCA(7–30, 4.26) than with the MMSE(16–30, 2.55). The percentage of subjects scoring below a cutoff of 26/30 (used by others to detect mild cognitive impairment) was higher on the MoCA (32%) than on the MMSE (11%)(P < 0.000002). Compared to the MMSE, the MoCA may be a more sensitive tool to identify early cognitive impairment in PD. © 2007 Movement Disorder Society
Coupling between limb tremor and postural sway in Parkinson's disease
Authors: Kerr Graham , Morrison Steven , Silburn Peter
Published: November 2007

Increased tremor and postural instability are motor problems commonly associated with Parkinson's disease (PD). Despite the similarity between these oscillatory forms, little is known about the relation between them, especially for individuals with enhanced tremor. This study was designed to examine the nature of any relation between center of pressure (COP) excursions and postural/resting limb tremor of young, older individuals, and Parkinsonian participants in their different medication states. The resting and postural tremor for the PD participants was characterized by a single, prominent peak frequency between 4 and 7 Hz. The postural tremor for young/older participants contained smaller peaks between 1 to 4 and 7 to 12 Hz although no prominent peak was seen in their resting tremor. The AP and ML COP dynamics of all participants was characterized by a major peak between 0.1 and 0.5 Hz. An additional peak was observed in the COP output of the PD participants between 4 and 7 Hz. While no tremor‐COP coupling was observed for the young/old groups, coherence analysis revealed a significant degree of coupling between COP motion and tremor between 4 and 7 Hz for PD participants. These results highlight that the amplified tremor in PD can manifest itself in COP dynamics. This finding may have implications for postural stability for this patient group. © 2007 Movement Disorder Society
Characterization of white matter alterations in phenylketonuria by magnetic resonance relaxometry and diffusion tensor imaging
Authors: Vermathen Peter , Robert‐Tissot Laure , Pietz Joachim , Lutz Thomas , Boesch Chris , Kreis Roland
Published: November 2007

A multimodal MR study including relaxometry, diffusion tensor imaging (DTI), and MR spectroscopy was performed on patients with classical phenylketonuria (PKU) and matched controls, to improve our understanding of white matter (WM) lesions. Relaxometry yields information on myelin loss or malformation and may substantiate results from DTI attributed to myelin changes. Relaxometry was used to determine four brain compartments in normal‐appearing brain tissue (NABT) and in lesions: water in myelin bilayers (myelin water, MW), water in gray matter (GM), water in WM, and water with long relaxation times (cerebrospinal fluid [CSF]‐like signals). DTI yielded apparent diffusion coefficients (ADCs) and fractional anisotropies. MW and WM content were reduced in NABT and in lesions of PKU patients, while CSF‐like signals were significantly increased. ADC values were reduced in PKU lesions, but also in the corpus callosum. Diffusion anisotropy was reduced in lesions because of a stronger decrease in the longitudinal than in the transverse diffusion. WM content and CSF‐like components in lesions correlated with anisotropy and ADC. ADC values in lesions and in the corpus callosum correlated negatively with blood and brain phenylalanine (Phe) concentrations. Intramyelinic edema combined with vacuolization is a likely cause of the WM alterations. Correlations between diffusivity and Phe concentrations confirm vulnerability of WM to high Phe concentrations. Magn Reson Med 58:1145–1156, 2007. © 2007 Wiley‐Liss, Inc.
A non‐volatile, bistable, and rewritable memory device fabricated with poly(nitroxide radical) and silver salt layers
Authors: Yonekuta Yasunori , Honda Kenji , Nishide Hiroyuki
Published: November 2007

A non‐volatile, bistable, and rewritable organic memory device was successfully fabricated with the layers of poly(2,2,6,6‐tetramethylpiperidine‐1‐oxyl methacrylate) (PTMA) and poly(methyl methacrylate) (PMMA) containing silver salt. The PTMA layer was employed as a p‐dopable material, while the silver salt‐dispersed PMMA layer acted as an n‐dopable material. The ON–OFF ratio between low‐conductivity and high‐conductivity states amounted to more than four orders of magnitude, and the retention time was longer than 103 sec. The device was characterized by excellent rewritability. Copyright © 2007 John Wiley & Sons, Ltd.
Erneuerung der abgehängten Decke in der Olympiaschwimmhalle in München
Authors: Göppert Knut , Linden Sebastian
Published: November 2007

Die Olympiaschwimmhalle als Bestandteil der Münchener Olympiabauten wurde anlässlich der Olympischen Sommerspiele 1972 erbaut. Nach über 30 Jahren Standzeit war die Tragfähigkeit der Membrankonstruktion der abgehängten Decke durch Alterung und äußere Einflüsse erschöpft. Der vorliegende Beitrag erläutert die Geschichte der abgehängten Decke der Schwimmhalle: die architektonischen, statischen und bauphysikalischen Anforderungen im Urzustand sowie die Planung und Ausführung der kürzlich fertiggestellten neuen abgehängten Decke.
Support for Simulation‐based Surgical Education through American College of Surgeons – Accredited Education Institutes
Authors: Sachdeva Ajit K. , Pellegrini Carlos A. , Johnson Kathleen A.
Published: November 2007

The American College of Surgeons (ACS) recently launched a new program to provide regional support for simulation‐based surgical education through the establishment of a consortium of accredited education institutes. The goals of the program are to enhance surgical patient safety, support efforts of surgeons to meet the requirements for Maintenance of Certification, address the core competencies that all surgeons and surgical residents need to achieve and demonstrate, and enhance access to contemporary surgical education. The ACS‐accredited institutes will comprehensively address the needs of a broad spectrum of learners and advance the science of simulation‐based surgical education. Accreditation is being offered at two levels—Level I (Comprehensive) and Level II (Basic)—based on three standards that focus on the learners served, the curricula offered, and the technological support and resources available. Initial plans of the consortium of ACS‐accredited Education Institutes include development and dissemination of innovative curricula, peer review of new educational programs and products, sharing of limited educational resources, and pursuit of collaborative research and development. This program should be of great value in supporting the professional activities of surgeons, surgical residents, medical students, and members of the surgical team, and in delivering surgical care of the highest quality.
The lipin protein family: Dual roles in lipid biosynthesis and gene expression
Authors: Reue Karen , Zhang Peixiang
Published: November 2007

The prevalence of obesity in the western world has focused attention on factors that influence triglyceride biosynthesis, storage, and utilization. Members of the lipin protein family have a newly discovered enzymatic role in triglyceride and phospholipid biosynthesis as a phosphatidate phosphatase, and also act as an inducible transcriptional coactivator in conjunction with peroxisome proliferator‐activated receptor γ (PPARγ) coactivator‐1α and PPARα. Through these activities, the founding member of the family, lipin‐1, influences lipid metabolism and glucose homeostasis in diverse tissues including adipose tissue, skeletal muscle, and liver. The physiological roles of lipin‐2 and lipin‐3 are less well defined, but are likely to carry out similar functions in glycerolipid biosynthesis and gene expression in a distinct tissue distribution.
FXR signaling in metabolic disease
Authors: Zhang Yanqiao , Edwards Peter A.
Published: November 2007

Farnesoid X receptor (FXR), a member of the nuclear receptor superfamily, has been shown to be important in controlling numerous metabolic pathways; these include roles in maintaining bile acid, lipid and glucose homeostasis, in preventing intestinal bacterial infection and gallstone formation and in modulating liver regeneration and tumorigenesis. The accumulating data suggest that FXR may be a pharmaceutical target for the treatment of certain metabolic diseases.
Nuclear receptors in macrophages: A link between metabolism and inflammation
Authors: Szanto Attila , Rőszer Tamás
Published: November 2007

In the past decade much effort has been made to understand the mechanisms how lipids are handled by macrophages and how inflammation could promote the atherogenic process. Here, we also provide an overview of these two fields.
Hume's Sceptical Materialism
Authors: Buckle Stephen
Published: November 2007

The paper argues that Hume's philosophy is best described as sceptical materialism. It is argued that the conjunction is not self-contradictory as long as ‘scepticism’ is understood in its ancient sense, as the denial of knowledge of the essences of things. It is further argued that scepticism (thus understood) and materialism are natural bedfellows, since a thoroughgoing materialism denies any special status to human rational powers. The content of theTreatise of Human Natureis then shown to conform to this understanding: theTreatiseconsistently employs an implicitly materialist faculty psychology in order to arrive at its sceptical standpoint. Finally, it is shown that Hume's philosophy can be understood to be a sceptical rewriting of the dogmatic materialism of Hobbes.
Authors: Gilbert Paul
Published: November 2007

“I hate war,” de Fontenelle confessed, “for it spoils conversation.” And does it spoil philosophy too, which is always a kind of conversation? Or can philosophers write about war, as now we surely must, in a way that keeps the conversation going without belligerence? Only so, perhaps, can philosophy shed light on this dark field; but how to do it is itself obscured by the passions that wars evoke. Ted Honderich advocates advocacy, “an advocacy of arguments and judgements. A decent philosopher dealing with moral and political questions … is in a line of life higher than that of a trial lawyer, but not out of sight of that line of life. If there is what can be called moral truth, it is not ordinary truth. Desire sits onto it” (7). Honderich's book may be viewed in this light as a sustained speech for the prosecution in the impeachment of Tony Blair and George W. Bush for waging terrorist war and supporting the terrorist wars of others. It is, then, a polemical work, but, unlike a lawyer's, founded on Honderich's own convictions, which are themselves rooted in philosophical belief.
Receiver function study of the crustal structure of the southeastern Caribbean plate boundary and Venezuela
Authors: Niu Fenglin , Bravo Tammy , Pavlis Gary , Vernon Frank , Rendon Herbert , Bezada Maximiliano , Levander Alan
Published: November 2007

We have investigated crustal thickness and composition across the southeastern Caribbean plate boundary with the receiver function technique. We used teleseismic data recorded by a temporary broadband array deployed under the BOLIVAR project and the permanent national seismic network of Venezuela. We used the primary P‐to‐S conversion and crustal reverberations to estimate crustal thickness and average crustal VP/VS ratio over the region. We observe large variations in crustal thickness and Poisson's ratio. Estimated Moho depth ranges from ∼16 km beneath the southeastern Caribbean Sea to ∼52 km beneath northeastern Venezuela and the Venezuelan Andes. There is a good correlation between crustal structure and tectonic terranes. Data from the Precambrian Guayana Shield suggest that the underlying crustal structure is relatively uniform with a moderate thickness (∼37 km) and an intermediate composition. A thick crust is found below the foreland basins. The two mountain systems in northern Venezuela, the Serrania del Interior and the Serrania del Falcon, have a thin crust with arc composition and are likely dynamically supported by elastic rebound or underthrusting of the oceanic plateau that characterizes the southern Caribbean. On the other hand, the Venezuelan Andes and Perija Range on the western side of the country are probably isostatically balanced by thick crustal roots.
An improved lattice Boltzmann model for multicomponent reactive transport in porous media at the pore scale
Authors: Kang Qinjun , Lichtner Peter C. , Zhang Dongxiao
Published: November 2007

In this paper, we improve the lattice Boltzmann pore‐scale model for multicomponent reactive transport in porous media developed in a previous study. Instead of applying a thermal boundary condition to solute transport, we rigorously derive the distribution function boundary condition for the total solute concentration. This is achieved first by correcting an expression of the particle distribution function in terms of the corresponding concentration and its gradient and then by deriving and using the relation that the nonequilibrium portion of the distribution function in opposite directions takes on opposite signs. We implement the new boundary condition in both the two‐dimensional nine‐speed (D2Q9) and four‐speed (D2Q4) lattices. Simulations of reactive transport in various chemical and geometrical systems using different models are carried out, and results are compared to analytic expressions or two‐dimensional FLOTRAN simulations. It is found that with this new boundary condition, the solute mass is strictly conserved by heterogeneous reactions, as was not the case using the thermal boundary condition. It is also found that compared with the D2Q9 model, the D2Q4 model has comparable accuracy and better computational efficiency.
Search for pick‐up ion generated Na+ cyclotron waves at Mercury
Authors: Boardsen S. A. , Slavin J. A.
Published: November 2007

Magnetometer data was examined from the two Mariner 10 passages through Mercury's magnetosphere for evidence of Na+ electromagnetic ion cyclotron waves (ICW). These waves are expected to be produced if the thermalization of newly created Na+ pick‐up ions occurs. We found no evidence of Na+ ICW. The spacecraft's rapid passage through Mercury's magnetosphere meant that the ambient magnetic field was only relatively constant for at most ∼3–4 Na+ ICW wave periods throughout each transversal, therefore limiting the spectral resolution of the Na+ cyclotron frequency. Our computations indicate that the wavelengths of Na+ ICW may be on the order of the system scale lengths. It is, therefore, questionable whether these waves can grow to sufficient amplitude to effectively thermalize these pick‐up ions and incorporate them into Mercury's magnetosphere.
Retrieval of large volcanic SO2 columns from the Aura Ozone Monitoring Instrument: Comparison and limitations
Authors: Yang Kai , Krotkov Nickolay A. , Krueger Arlin J. , Carn Simon A. , Bhartia Pawan K. , Levelt Pieternel F.
Published: November 2007

To improve global measurements of atmospheric sulfur dioxide (SO2), we have developed a new technique, called the linear fit (LF) algorithm, which uses the radiance measurements from the Ozone Monitoring Instrument (OMI) at a few discrete ultraviolet wavelengths to derive SO2, ozone, and effective reflectivity simultaneously. We have also developed a sliding median residual correction method for removing both the along‐ and cross‐track biases from the retrieval results. The achieved internal consistencies among the LF‐retrieved geophysical parameters clearly demonstrate the success of this technique. Comparison with the results from the Band Residual Difference technique has also illustrated the drastic improvements of this new technique at high SO2 loading conditions. We have constructed an error equation and derived the averaging kernel to characterize the LF retrieval and understand its limitations. Detailed error analysis has focused on the impacts of the SO2 column amounts and their vertical distributions on the retrieval results. The LF algorithm is robust and fast; therefore it is suitable for near real‐time application in aviation hazards and volcanic eruption warnings. Very large SO2 loadings (>100 DU) require an off‐line iterative solution of the LF equations to reduce the retrieval errors. Both the LF and sliding median techniques are very general so that they can be applied to measurements from other backscattered ultraviolet instruments, including the series of Total Ozone Mapping Spectrometer (TOMS) missions, thereby offering the capability to update the TOMS long‐term record to maintain consistency with its OMI extension.
Reinvestigation of the electronic spectroscopy of the Au–Ar complex
Authors: Plowright Richard J. , Ayles Victoria L. , Watkins Mark J. , Gardner Adrian M. , Wright Rossana R. , Wright Timothy G. , Breckenridge W. H.
Published: November 2007

The Au–Ar complex is reinvestigated employing resonance-enhanced multiphoton ionization spectroscopy. Spectra are reported, corresponding to the atomic transition Au(6p←6s). This electronic excitation yields Π2 and Σ+2 states of Au–Ar, which interact under the influence of spin-orbit coupling. The spectra are consistent with strong σ-π mixing induced by the large spin-orbit coupling of Au, leading to strong interaction of the two Ω=1∕2 states, which arise from the Ar(S01)+Au(P1∕2,3∕22) asymptotes, and the consequent formation of a “shelf” on the outer wall of the lowest Ω=1∕2 state. In addition, high-level ab initio calculations are reported on the ground electronic state, X̃Σ+2, including extrapolation to the basis set limit.
An analytical derivative procedure for the calculation of vibrational Raman optical activity spectra
Authors: Liégeois Vincent , Ruud Kenneth , Champagne Benoît
Published: November 2007

We present an analytical time-dependent Hartree-Fock algorithm for the calculation of the derivatives of the electric dipole–magnetic dipole polarizability with respect to atomic Cartesian coordinates. Combined with analogous procedures to determine the derivatives of the electric dipole–electric dipole and electric dipole–electric quadrupole polarizabilities, it enables a fully analytical evaluation of the three frequency-dependent vibrational Raman optical activity (VROA) invariants within the harmonic approximation. The procedure employs traditional non-London atomic orbitals, and the gauge-origin dependence of the VROA intensities has, therefore, been assessed for the commonly used aug-cc-pVDZ and rDPS:3-21G basis sets.
On a three-dimensional implementation of the baker’s transformation
Authors: Carrière Philippe
Published: November 2007

A three-dimensional, steady flow configuration intended to mimic the baker’s map is studied by means of numerical simulation. The Poincaré sections computed from a finite element solution of the velocity field show that the behavior is dominated by chaotic advection. The value obtained for the Lyapunov exponent is very close to the theoretical value of ln2 predicted by the baker’s map.
Electronic properties and dopant pairing behavior of manganese in boron-doped silicon
Authors: Roth T. , Rosenits P. , Diez S. , Glunz S. W. , Macdonald D. , Beljakowa S. , Pensl G.
Published: November 2007

Boron-doped silicon wafers implanted with low doses of manganese have been analyzed by means of deep-level transient spectroscopy (DLTS), injection-dependent lifetime spectroscopy, and temperature-dependent lifetime spectroscopy. While DLTS measurements allow the defect levels and majority carrier capture cross sections to be determined, the lifetime spectroscopy techniques allow analysis of the dominant recombination levels and the corresponding ratios of the capture cross sections. Interstitial manganese and manganese-boron pairs were found to coexist, and their defect parameters have been investigated. In good agreement with the literature, this study identifies the defect level of manganese-boron pairs to be located in the lower half of the band gap at an energy level of Ev+0.55 eV with a majority carrier capture cross section of σp=3.5×10−13 cm2. The capture cross-section ratio was found to be k=σn∕σp=6.0. This implies that the previously unknown minority carrier capture cross section is σn=2.1×1012 cm2. Concerning the defect related to interstitial manganese, this study identifies the most recombination-active level to be located in the upper half of the band gap at EC−0.45 eV with a corresponding ratio of the capture cross sections of k=9.4. In addition, the temperature-dependent association time constant of manganese-boron pairs is determined to be τassoc,Mn=8.3×105 K−1 cm−3(T∕Ndop)exp(0.67 eV∕kBT) and found to differ from that for iron by a factor of 3 at room temperature, allowing this association time constant to be used as a fingerprint for a possible contamination with manganese. Also, the diffusion coefficient of interstitial manganese in silicon is determined from these experiments in a temperature range from 70 to 120 °C. It can be represented by the expression DMn=6.9×10−4 cm2 s−1 exp(−0.67 eV∕kBT).
Invited Article: An improved double-toroidal spectrometer for gas phase (e,2e) studies
Authors: Lower J. , Panajotović R. , Bellm S. , Weigold E.
Published: November 2007

A new spectrometer is described for measuring the momentum distributions of scattered electrons arising from electron-atom and electron-molecule ionization experiments. It incorporates and builds on elements from a number of previous designs, namely, a source of polarized electrons and two high-efficiency electrostatic electron energy analyzers. The analyzers each comprise a seven-element retarding-electrostatic lens system, four toroidal-sector electrodes, and a fast position-and-time-sensitive two-dimensional delay-line detector. Results are presented for the electron-impact-induced ionization of helium and the elastic scattering of electrons from argon and helium which demonstrate that high levels of momentum resolution and data-collection efficiency are achieved. Problematic aspects regarding variations in collection efficiency over the accepted momentum phase space are addressed and a methodology for their correction presented. Principles behind the present design and previous designs for electrostatic analyzers based around electrodes of toroidal-sector geometry are discussed and a framework is provided for optimizing future devices.
Multiple reactions and trace species in the Direct Simulation Monte Carlo Macroscopic Chemistry Method
Authors: Goldsworthy M. J. , Macrossan M. N. , Abdel-Jawad M. M.
Published: November 2007

The Macroscopic Chemistry Method is a technique for modeling chemical reactions in the Direct Simulation Monte Carlo (DSMC) method. The approach differs from conventional DSMC chemistry methods in that the change in the number of each species over a time step is calculated from the overall macroscopic cell parameters, rather than on a collision pair basis. The Macroscopic Chemistry Method (MCM) can be applied in flows where the collision rate is highly nonequilibrium and has previously been applied to model dissociation-recombination reactions of a symmetrical diatomic gas. Here we propose a procedure for applying MCM to a multiple species reaction set that includes exchange reactions, as well as a method by which trace species can be modeled without the need for variable weighting factors. The procedure is tested in constant volume reservoir relaxation simulations of a high-temperature gas and quasi-one-dimensional expansion of a high-speed, high-temperature gas. Initial compositions are chosen to resemble Earth and Martian atmosphere reacting systems. For the reservoir relaxation simulations, comparisons of the species mole fractions and overall temperature predicted by MCM are made with numerical integration of the reaction rate equations. For the one-dimensional expansion, results using the trace species algorithm are compared with a simulation without the trace species algorithm but with a much larger number of simulator particles. The reaction set consists of 54 chemical reactions (40 dissociation and 14 exchange reactions) among 8 species. The trace species algorithm exactly reproduces the temperature history predicted by numerical integration for the reservoir simulation. Without the trace species algorithm, the errors in the mole fractions are proportional to the inverse of the number of simulator particles used. For both the reservoir and expansion flow simulations, the trace species algorithm gives an improvement in accuracy equivalent to using 100 times the number of simulator particles.
Magnetic needles encapsulated inside (BN)36 cage: Prediction of atomic, electronic, and magnetic structure from first principle calculations
Authors: Nigam Sandeep , Majumder Chiranjib
Published: November 2007

Using the first principle based density functional theory formalism, we report the stability and structural aspects of small magnetic clusters inside chemically inert (BN)36 cage. Although the atomic structures of small clusters showed significant changes due to the restrained imposed by the cage size, their stability improves inside the cage. Moreover, their magnetic structure remains almost unaltered inspite of being encaged. The implication of this work indicates that small magnetic particles can be protected inside the BN cage without losing their magnetic character for further applications.
Structural and electrical characterization of room temperature ultra-high-vacuum compatible SiO2 for gating scanning tunneling microscope-patterned devices
Authors: Scappucci G. , Ratto F. , Thompson D. L. , Reusch T. C. G. , Pok W. , Rueß F. J. , Rosei F. , Simmons M. Y.
Published: November 2007

We present an ultrahigh vacuum technique for depositing SiO2 at room temperature using an atomic oxygen source and Si coevaporation for ultimate use as a dielectric for gating Si devices with atomically precise dopant profiles. The resulting SiO2 layers were characterized in situ by scanning tunneling microscopy, ex situ by transmission electron microscopy and ellipsometry and integrated as the gate dielectric in a metal oxide semiconductor field effect transistor (MOSFET). The electrical characteristics of the MOSFETs were investigated at 4.2K, giving an interface trap density of ∼1011cm−2 from conductance and Hall effect measurements.
Enhancement of light extraction efficiency of InGaN quantum wells light emitting diodes using SiO2/polystyrene microlens arrays
Authors: Ee Yik-Khoon , Arif Ronald A. , Tansu Nelson , Kumnorkaew Pisist , Gilchrist James F.
Published: November 2007

Improvement of light extraction efficiency of InGaN quantum wells light emitting diodes (LEDs) using SiO2/polystyrene microspheres was demonstrated experimentally. The utilization of SiO2/polystyrene microlens arrays on InGaN quantum wells LEDs, deposited via rapid convective deposition, allows the increase of the effective photon escape cone and reduction in the Fresnel reflection. Improvement of output power by 219% for InGaN quantum wells LEDs emitting at peak wavelength of 480nm with SiO2/polystyrene microspheres microlens arrays was demonstrated.
Metal films on polymer substrates stretched beyond 50%
Authors: Lu Nanshu , Wang Xi , Suo Zhigang , Vlassak Joost
Published: November 2007

When a freestanding plastically deformable metal film is stretched, it ruptures by strain localization, and the elongation is less than a few percent. When the film is deposited on a polymer substrate, however, strain localization may be retarded by the substrate. This paper reports Cu films deposited on Kapton substrates and stretched up to the rupture of the substrates (at an elongation between 50% and 60%). When Cr adhesion layers are introduced between Cu and Kapton, few microcracks in Cu may be found, and the measured electrical resistance agrees with a theoretical prediction. Micrographs show that the strain localization and debonding coevolve.
Chemical gases sensing properties of diamond nanocone arrays formed by plasma etching
Authors: Wang Q. , Qu S. L. , Fu S. Y. , Liu W. J. , Li J. J. , Gu C. Z.
Published: November 2007

A uniform diamond nanocone array was formed by plasma etching of diamond film in a hot filament chemical vapor deposition (HFCVD) system. A surface amorphous carbon coating layer, which is formed during CH4/H2 plasma-etching process, was removed by Ar plasma in a reactive ion etching system. The hydrogenation of diamond nanocones was performed in H2 ambience by using the same HFCVD system. The air-diluted NH3 and NO2 gases sensing properties of the diamond cone arrays had been studied by using electric current versus measurement time characteristics at room temperature. The repeatable chemical sensing properties of the hydrogenated diamond cone array sensor are enhanced, in comparison with as-formed diamond film. Surface two-dimensional hole gas structure and greatly increased surface-to-volume ratio both play a key role for the excellent detection performance. As-formed diamond nanocone arrays show a promising prospect for applications as chemical sensor for both reducing (NH3) and oxidizing (NO2) gases.
Electrowetting-assisted drop deposition for controlled spotting
Authors: Leïchlé T. , Tanguy L. , Nicu L.
Published: November 2007

Electrowetting is used to assist the delivery of droplets by a contact method. The electroassisted liquid dispensing technique enables to monitor the drop size via the voltage applied between the tool, i.e., silicon cantilevers and the deposition surface. Voltages ranging from 0to210V are used to deposit water-glycerol drops with diameters and volumes in the ranges of 5–40μm and 20fL–14pL. The presented results demonstrate that electrowetting-assisted deposition is of special interest for patterning applications requiring large features to be directly and quickly written using a minimum volume of reagents.
Periodicity dependence of the ferroelectric properties in BiFeO3∕SrTiO3 multiferroic superlattices
Authors: Ranjith R. , Kundys B. , Prellier W.
Published: November 2007

Artificial superlattices of (BiFeO3)m(SrTiO3)m (m=1–10 unit cells) consisting of multiferroic BiFeO3 and insulating SrTiO3 layers were fabricated on (100)-oriented SrTiO3 substrates by pulsed laser ablation. The remnant polarization and leakage current behavior of these films were studied by varying the periodicity (8–80Å) of the superlattice. Compared to single layer BiFeO3 thin films, the leakage current was reduced by a few orders of magnitude on increasing the periodicity. Reduced leakage and intrinsic polarization hysteresis were observed and confirmed by pulsed polarization analysis for all periodicities (∼20–60Å). The leakage current was dominated by space charge limited conduction.
Lithium superionic conduction in lithium borohydride accompanied by structural transition
Authors: Matsuo Motoaki , Nakamori Yuko , Orimo Shin-ichi , Maekawa Hideki , Takamura Hitoshi
Published: November 2007

The electrical conductivity of lithium borohydride (LiBH4) measured by the ac complex impedance method jumped by three orders of magnitude due to structural transition from orthorhombic to hexagonal at approximately 390K. The hexagonal phase exhibited a high electrical conductivity of the order of 10−3Scm−1. Furthermore, the conductivity calculated from the Nernst-Einstein equation using the correlation time obtained from Li7 nuclear magnetic resonance was in good agreement with the measured electrical conductivity. It was concluded that the electrical conductivity in the hexagonal phase is due to the Li superionic conduction.
Effects of interfacial stability between electron transporting layer and cathode on the degradation process of organic light-emitting diodes
Authors: Chu Ta-Ya , Lee Yong-Han , Song Ok-Keun
Published: November 2007

The authors have demonstrated that the increase of electron injection barrier height between tris(8-hydroxyquinoline)aluminum (Alq3) and LiF∕Al cathode is one of the most critical parameters to determine the reliability of organic light-emitting diode with the typical structure of indium tin oxide/N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl) benzidine/Alq3∕LiF∕Al. The electrical properties of several devices (hole only, electron only, and integrated double-layered devices) have been measured in the function of operating time to analyze the bulk and interface property changes. Bulk properties of trap energy and mobility in an organic layer have been estimated by using trap-charge-limited currents and transient electroluminescence measurements.
Room-temperature atmospheric argon plasma jet sustained with submicrosecond high-voltage pulses
Authors: Walsh J. L. , Kong M. G.
Published: November 2007

In this letter, an experimental study is presented to characterize a room-temperature plasma jet in atmospheric argon generated with submicrosecond voltage pulses at 4kHz. Distinct from sinusoidally produced argon discharges that are prone to thermal runaway instabilities, the pulsed atmospheric argon plasma jet is stable and cold with an electron density 3.9 times greater than that in a comparable sinusoidal jet. Its optical emission is also much stronger. Electrical measurement suggests that the discharge event is preceded with a prebreakdown phase and its plasma stability is facilitated by the short voltage pulses.