bluuebunny/crossref_metadata_2025 huggingface dataset:
A precision translation stage for reproducing measured target volume motions
Authors: Litzenberg Dale W. , Hadley Scott W. , Lam Kwok L. , Balter James M.
Published: August 2007

The development of four‐dimensional (4D) imaging, treatment planning, and treatment delivery methods for radiation therapy requires a quality assurance device that can reproduce clinical motions. Here, we present a high‐precision translation stage for testing and validating 4D techniques. These techniques may require spatial resolutions of 1 mm and temporal resolutions of 2 – 30 Hz for computed tomography imaging, electromagnetic tracking, and fluoroscopic imaging. A one‐dimensional programmable translation stage capable of reproducing idealized and measured anatomic motions common to the thorax and providing support for phantoms weighing up to 27 kg was designed and built to meet the foregoing spatial and temporal resolution requirements. The stage consists of a polycarbonate base and table, driven by an ac servo motor with encoder feedback by means of a belt‐coupled precision screw. Complex motions are made possible by a programmable motion controller that can run multiple independent control and monitoring programs concurrently on independent motion axes. Programmable input and output ports allow motion to be synchronized with beam delivery and other imaging and treatment delivery devices to within 2.0 ms. Average deviations from the programmed positions are typically 0.2 mm or less, and the average maximum positional errors are typically 0.5 mm for an indefinite number of parameterized breathing motion cycles during reproduction of measured target volume motions for several minutes.

PACS number: 87.66.Xa
Quantitative assessment of four‐dimensional computed tomography image acquisition quality
Authors: Starkschall George , Desai Neil , Balter Peter , Prado Karl , Luo Dershan , Cody Dianna , Pan Tinsu
Published: August 2007

The purpose of the present work was to describe the development and validation of a series of tests to assess the quality of four‐dimensional (4D) computed‐tomography (CT) imaging as it is applied to radiation treatment planning. Using a commercial respiratory motion phantom and a programmable moving platform with a CT phantom, we acquired 4D CT datasets on two commercial multislice helical CT scanners that use different approaches to 4D CT image reconstruction. Datasets were obtained as the platform moved in various patterns designed to simulate breathing. Known inserts in the phantom were contoured, and statistics were generated to evaluate properties important to radiation therapy—namely, accuracy of phase‐binning, shape, volume, and CT number. Phase‐binning accuracy varied by as much as 5% for a 4D procedure in which images were reconstructed and then binned, but exhibited no variation for a 4D procedure in which projections were binned before reconstruction. The magnitude of geometric distortion was found to be small for both approaches, as was the magnitude of volume error. Partial‐volume effects in the direction perpendicular to the transverse planes of reconstruction affected volume accuracy, however. Computed tomography numbers were reproduced accurately, but 4D images exhibited more variation in CT number than static CT images did. Characterization of such properties can be used to better understand and optimize the various parameters that affect 4D CT image quality.

PACS numbers: 87.53.‐j, 87.59.Fm
Commissioning and acceptance testing of a CyberKnife linear accelerator
Authors: Sharma Subhash C. , Ott Joseph T. , Williams Jamone B. , Dickow Danny
Published: August 2007

Acceptance testing and commissioning of a CyberKnife robotic stereotactic radiosurgery system was performed in April 2006. The CyberKnife linear accelerator produces a photon beam of 6 MV nominal energy, without the use of a flattening filter. Clinically measured tissue–phantom ratios, off‐center ratios, and output factors are presented and compared with similar data from other CyberKnife sites throughout the United States. In general, these values agreed to within 2%.

PACS number: 87.53.Dq
Lag correction model and ghosting analysis for an indirect‐conversion flat‐panel imager
Authors: Mail Noor , O'Brien Peter , Pang Geordi
Published: August 2007

Cone‐beam digital tomosynthesis (CBDT) is a new approach that was recently proposed for rapid tomographic imaging of soft‐tissue targets in the radiotherapy treatment room. One of the potential problems in implementing CBDT using, for example, megavoltage (MV) X rays is the possibility of artifacts caused by image lag and ghosting of the X‐ray detector used. In the present work, we developed a model to correct for image lag with indirect‐conversion flat‐panel imagers (FPIs) used for MV‐CBDT. This model is based on measurement and analysis of image lag in an indirect‐conversion FPI irradiated with a 6‐MV X‐ray beam. Our results demonstrated that image lag is amenable to correction. In addition, we measured the ghosting effect for an indirect‐conversion FPI and found it to be insignificant.

PACS numbers: 87.53.Oq, 87.57.Ce
Dietary Inclusion of Colicin E1 Is Effective in Preventing Postweaning Diarrhea Caused by F18-Positive
Escherichia coli
in Pigs
Authors: Cutler S. A. , Lonergan S. M. , Cornick N. , Johnson A. K. , Stahl C. H.
Published: August 2007

With worldwide concern over the use of antibiotics in animal agriculture and their contribution to the spread of antibiotic resistance, alternatives to conventional antibiotics are needed. Previous research in our laboratories has shown that colicin E1 is effective against some
Escherichia coli
strains responsible for postweaning diarrhea (PWD) in vitro. In this study we examined the efficacy of the dietary inclusion of colicin E1 in preventing experimentally induced PWD caused by F18-positive enterotoxigenic
E. coli
in young pigs. Twenty-four weaned pigs (23 days of age), identified by genotyping to be susceptible to F18-positive
E. coli
infections, were individually housed and fed diets containing 0, 11, or 16.5 mg colicin E1/kg diet. Two days after the start of the trial, all animals were orally inoculated with 1 × 10
9
CFU of each of two F18-positive
E. coli
strains isolated from pigs with PWD. The dietary inclusion of colicin E1 decreased the incidence and severity of PWD caused by F18-positive enterotoxigenic
E. coli
and improved the growth performance of the piglets. Additionally, the reduced incidence of PWD due to dietary colicin E1, lowered the levels of expression of the genes for interleukin 1β and tumor necrosis factor beta in ileal tissues from these animals. The dietary inclusion of colicin E1 may be an effective alternative to conventional antibiotics in the diets of weaning pigs for the prevention of PWD caused by F18-positive enterotoxigenic
E. coli
.
Prevalence and Expression of the Plasmid-Mediated Quinolone Resistance Determinant
qnrA1
Authors: Xu Xiaogang , Wu Shi , Ye Xinyu , Liu Yang , Shi Wanliang , Zhang Yingyuan , Wang Minggui
Published: August 2007

Since its discovery,
qnrA
has been found in most common
Enterobacteriaceae
. Ciprofloxacin MICs conferred by different
qnrA
-positive plasmids could range from 0.1 μg/ml to 2 μg/ml in
Escherichia coli
J53. The reasons for different ciprofloxacin MICs conferred by
qnrA
have not been fully clarified. Five hundred forty-one consecutive gram-negative clinical strains that were resistant or intermediate to ciprofloxacin and that were isolated in Shanghai in 2005 were screened for
qnrA
by PCR. For
qnrA
-positive isolates, the transferability of quinolone resistance was determined by conjugation and mutations within the quinolone resistance-determining region (QRDR) of
gyrA
and
parC. aac
(
6
′)-
Ib-cr
was detected and
qnrA
RNA expression was determined using real-time reverse transcription-PCR for transconjugants with different ciprofloxacin MICs. The
qnrA
gene was detected in 7 of the 541 clinical isolates. Quinolone resistance was transferred in four strains by conjugation. Mutations in the QRDR of
gyrA
and
parC
were detected in five
qnrA
-positive clinical strains with higher ciprofloxacin MICs. Of four
qnrA
-bearing plasmids in
E. coli
J53, pHS4 and pHS5 conferred ciprofloxacin MICs of 0.094 to 0.125 μg/ml; pHS3, which harbored the
aac
(
6
′)-
Ib-cr
gene as well, conferred a ciprofloxacin MIC of 0.25 μg/ml, and pHS6, which had both the
aac
(
6
′)-
Ib-cr
gene and a high expression level of
qnrA
, had a ciprofloxacin MIC of 1.0 μg/ml. The prevalence of
qnrA
appeared to be higher in
Enterobacter cloacae
than in other
Enterobacteriaceae
. The coexistence of
qnrA
and
aac
(
6
′)-
Ib-cr
in a single plasmid and increased
qnrA
expression can account for the different levels of ciprofloxacin resistance seen in transconjugants.
Variations in Reverse Transcriptase and RNase H Domain Mutations in Human Immunodeficiency Virus Type 1 Clinical Isolates Are Associated with Divergent Phenotypic Resistance to Zidovudine
Authors: Ntemgwa Michel , Wainberg Mark A. , Oliveira Maureen , Moisi Daniela , Lalonde Richard , Micheli Valeria , Brenner Bluma G.
Published: August 2007

Mutations in the RNase H domain of human immunodeficiency virus type 1 RT have been reported to cause resistance to zidovudine (ZDV) in vitro. However, very limited data on the in vivo relevance of these mutations in patients exist to date. This study was designed to determine the relationship between mutations in the RNase H domain and viral susceptibility to nucleoside analogues. Viruses harboring complex thymidine analogue mutation (TAM) and nucleoside analogue mutation (NAM) profiles were evaluated for their phenotypic susceptibilities to ZDV, tenofovir (TNF), and the nonapproved nucleoside reverse transcriptase inhibitors (NRTIs) β-2′,3′-didehydro-2′,3′-dideoxy-5-fluorocytidine (Reverset), β-d-5-fluorodioxolane-cytosine, and apricitabine. As controls, viruses from NRTI-naïve patients were also studied. ThepolRT region (codons 21 to 250) of the viruses were sequenced and evaluated for mutations in the RNase H domain (codons 441 to 560) and the connection domain (codons 289 to 400). The results showed that viruses from patients failing multiple NRTI-containing regimens had distinct TAM and NAM profiles that conferred various degrees of resistance to ZDV (0.9- to >300-fold). Sequencing of the RNase H domain identified five positions (positions 460,468, 483, 512, and 519) at which extensive amino acid polymorphisms common in both wild-type viruses and viruses from treated patients were identified. No mutations were observed at positions 539 and 549, which have previously been associated with ZDV resistance. Mutations in the RNase H domain did not appear to correlate with the levels of phenotypic resistance to ZDV. Although some mutations were also observed in the connection domain, the simultaneous presence of the L74V and M184V mutations was the most significant determinant of phenotypic resistance to ZDV in patients infected with viruses with TAMs.
Crystal Structure of Cefditoren Complexed with
Streptococcus pneumoniae
Penicillin-Binding Protein 2X: Structural Basis for Its High Antimicrobial Activity
Authors: Yamada Mototsugu , Watanabe Takashi , Miyara Takako , Baba Nobuyoshi , Saito Jun , Takeuchi Yasuo , Ohsawa Fukuichi
Published: August 2007

Cefditoren is the active form of cefditoren pivoxil, an oral cephalosporin antibiotic used for the treatment of respiratory tract infections and otitis media caused by bacteria such as
Streptococcus pneumoniae
,
Haemophilus influenzae
,
Streptococcus pyogenes
,
Klebsiella pneumoniae
, and methicillin-susceptible strains of
Staphylococcus aureus
. β-Lactam antibiotics, including cefditoren, target penicillin-binding proteins (PBPs), which are membrane-associated enzymes that play essential roles in the peptidoglycan biosynthetic process. To envision the binding of cefditoren to PBPs, we determined the crystal structure of a trypsin-digested form of PBP 2X from
S. pneumoniae
strain R6 complexed with cefditoren. There are two PBP 2X molecules (designated molecules 1 and 2) per asymmetric unit. The structure reveals that the orientation of Trp374 in each molecule changes in a different way upon the formation of the complex, but each forms a hydrophobic pocket. The methylthiazole group of the C-3 side chain of cefditoren fits into this binding pocket, which consists of residues His394, Trp374, and Thr526 in molecule 1 and residues His394, Asp375, and Thr526 in molecule 2. The formation of the complex is also accompanied by an induced-fit conformational change of the enzyme in the pocket to which the C-7 side chain of cefditoren binds. These features likely play a role in the high level of activity of cefditoren against
S. pneumoniae
.
In Vitro Activity of Human β-Defensin 2 againstPseudomonas aeruginosain the Presence of Tear Fluid
Authors: Huang Ling C. , Redfern Rachel L. , Narayanan Srihari , Reins Rose Y. , McDermott Alison M.
Published: August 2007

Pseudomonas aeruginosacauses vision-threatening keratitis and is difficult to treat due to emerging resistance. Human β-defensin 2 (hBD-2) is an antimicrobial peptide expressed by ocular surface epithelia with broad-spectrum activity against various pathogens, includingP. aeruginosa. The activity of hBD-2 againstP. aeruginosain the presence of human tears or NaCl was studied. In some experiments, tears were heat-inactivated, filtered, and separated into cationic/anionic fractions or mucin MUC5AC was removed by immunoprecipitation before use. Immunoprecipitation was performed to study the interaction between hBD-2 and MUC5AC. hBD-2 activity was reduced by 40 to 90% in the presence of 17.5 to 70% (vol/vol) tears. NaCl reduced hBD-2 activity, but at most it could account for only 36% of the inhibitory effect of tears. Heat inactivation and filtration attenuated the ability of tears to inhibit hBD-2 activity by 65 and 68%, respectively. Anionic tear fractions significantly reduced (86%) the activity of hBD-2, whereas only a 22% reduction was observed with the cationic fractions. In the absence of MUC5AC, the activity of hBD-2 was restored by 64%. Immunoprecipitation studies suggested that the loss of hBD-2 activity in tears is due to a direct binding interaction with MUC5AC. Our data showed that the antimicrobial activity of hBD-2 is sensitive to the presence of human tears and that this is partly due to the salt content and also the presence of MUC5AC. These data cast doubt on the effectiveness of hBD-2 as an antimicrobial peptide, and additional studies are required to conclusively elucidate its role in innate immunity at the ocular surface in vivo.
Concentration-Dependent
Mycobacterium tuberculosis
Killing and Prevention of Resistance by Rifampin
Authors: Gumbo Tawanda , Louie Arnold , Deziel Mark R. , Liu Weiguo , Parsons Linda M. , Salfinger Max , Drusano George L.
Published: August 2007

Rifampin is a cornerstone of modern antituberculosis therapy. However, rifampin's half-life of 3 h is believed to limit its utility for intermittent therapy, so new congeners with long half-lives are being developed. Using an in vitro pharmacokinetic-pharmacodynamic model of tuberculosis, we examined the relationships between rifampin exposure, microbial killing of log-phase-growth
Mycobacterium tuberculosis
, and suppression of resistance. Rifampin's microbial killing was linked to the area under the concentration-time curve-to-MIC ratio. The suppression of resistance was associated with the free peak concentration (
C
max
)-to-MIC ratio and not the duration that the rifampin concentration was above MIC. Rifampin prevented resistance to itself at a free
C
max
/MIC ratio of ≥175. The postantibiotic effect duration was ≥5.2 days and was most closely related to the
C
max
/MIC ratio (
r
2
= 0.96). To explain rifampin's concentration-dependent effect, we examined the kinetics of rifampin entry into
M. tuberculosis
. Rifampin achieved concentration-dependent intracellular steady-state concentrations within 15 min. Our results suggest that doses of rifampin higher than those currently employed would optimize the effect of rifampin, if patients could tolerate them. Another major implication is that in the design of new rifampin congeners for intermittent therapy, the important properties may include (i) the efficient entry of the rifamycin into
M. tuberculosis
, (ii) the achievement of a free
C
max
/MIC of >175 that can be tolerated by patients, and (iii) a long postantibiotic effect duration.
Anthrax Protective Antigen Cleavage and Clearance from the Blood of Mice and Rats
Authors: Moayeri Mahtab , Wiggins Jason F. , Leppla Stephen H.
Published: August 2007

Bacillus anthracis
protective antigen (PA) is an 83-kDa (PA83) protein that is cleaved to the 63-kDa protein (PA63) as an essential step in binding and internalizing lethal factor (LF). To assess in vivo receptor saturating PA concentrations, we injected mice with PA variants and measured the PA remaining in the blood at various times using PA83- and PA63-specific enzyme-linked immunosorbent assays. We found that both wild-type PA (WT-PA) and a receptor-binding-defective mutant (Ub-PA) were cleaved to PA63 independent of their ability to bind cells. This suggested a PA-acting protease activity in the blood. The protease cleaved PA at the furin cleavage sequence because furin site-modified PA mutants were not cleaved. Cleavage measured in vitro was leupeptin sensitive and dependent on calcium. Cell surface cleavage was important for toxin clearance, however, as Ub-PA and uncleavable PA mutants were cleared at slower rates than WT-PA. The cell binding-independent cleavage of PA was also verified by using Ub-PA (which is still cleaved) to rescue mice from toxin challenge by competitively binding circulating LF. This mutant was able to rescue mice even when given 12 h before toxin challenge. Its therapeutic ability was comparable to that of dominant-negative PA, which binds cells but does not allow LF translocation, and to the protection afforded through receptor clearance by WT-PA and uncleavable receptor binding-competent mutants. The PA cleavage and clearance observed in mice did not appear to have a role in the differential mouse susceptibility as it occurred similarly in lethal toxin (LT)-resistant DBA/2J and LT-sensitive BALB/cJ mice. Interestingly, PA63 was not found in LT-resistant or -sensitive rats and PA83 clearance was slower in rats than in mice. Finally, to determine the minimum amount of PA required in circulation for LT toxicity in mice, we administered time-separated injections of PA and LF and showed that lethality of LF for mice after PA was no longer measurable in circulation, suggesting active PA sequestration at tissue surfaces.
Impact of Alcaligin Siderophore Utilization on In Vivo Growth of
Bordetella pertussis
Authors: Brickman Timothy J. , Armstrong Sandra K.
Published: August 2007

Bordetella pertussis
, the causative agent of human whooping cough, or pertussis, is an obligate human pathogen with diverse high-affinity transport systems for the assimilation of iron, a biometal that is essential for growth. Under iron starvation stress conditions,
B. pertussis
produces the siderophore alcaligin. The alcaligin siderophore gene cluster, consisting of the
alcABCDERS
and
fauA
genes, encodes activities required for alcaligin biosynthesis, the export of the siderophore from the cell, the uptake of the ferric alcaligin complex across the outer membrane, and the transcriptional activation of alcaligin system genes by an autogenous mechanism involving alcaligin sensing. The
fauA
gene encodes a 79-kDa TonB-dependent outer membrane receptor protein required for the uptake and utilization of ferric alcaligin as an iron source. In this study, using mixed-infection competition experiments in a mouse respiratory model, inactivation of the
B. pertussis
ferric alcaligin receptor protein was found to have a profound impact on in vivo growth and survival of a
fauA
mutant compared with a coinfecting wild-type strain. The attenuating effect of
fauA
inactivation was evident early in the course of the infection, suggesting that the contribution of ferric alcaligin transport to the ecological fitness of
B. pertussis
may be important for adaptation to iron-restricted host conditions that exist at the initial stages of infection. Alcaligin-mediated iron acquisition by
B. pertussis
may be critical for successful host colonization and establishment of infection.
Modulation of Host Innate Immune Response in the Bladder by UropathogenicEscherichia coli
Authors: Billips Benjamin K. , Forrestal Sarah G. , Rycyk Matthew T. , Johnson James R. , Klumpp David J. , Schaeffer Anthony J.
Published: August 2007

UropathogenicEscherichia coli(UPEC), the most frequent cause of urinary tract infection (UTI), is associated with an inflammatory response which includes the induction of cytokine/chemokine secretion by urothelial cells and neutrophil recruitment to the bladder. Recent studies indicate, however, that UPEC can evade the early activation of urothelial innate immune response in vitro. In this study, we report that infection with the prototypic UPEC strain NU14 suppresses tumor necrosis factor alpha (TNF-α)-mediated interleukin-8 (CXCL-8) and interleukin-6 (CXCL-6) secretion from urothelial cell cultures compared to infection with a type 1 piliatedE. coliK-12 strain. Furthermore, examination of a panel of clinicalE. coliisolates revealed that 15 of 17 strains also possessed the ability to suppress cytokine secretion. In a murine model of UTI, NU14 infection resulted in diminished levels of mRNAs encoding keratinocyte-derived chemokine, macrophage inflammatory peptide 2, and CXCL-6 in the bladder relative to infection with anE. coliK-12 strain. Furthermore, reduced stimulation of inflammatory chemokine production during NU14 infection correlated with decreased levels of bladder and urine myeloperoxidase and increased bacterial colonization. These data indicate that a broad phylogenetic range of clinicalE. coliisolates, including UPEC, may evade the activation of innate immune response in the urinary tract, thereby providing a pathogenic advantage.
Identification of LpxL, a Late Acyltransferase of
Francisella tularensis
Authors: McLendon Molly K. , Schilling Birgit , Hunt Jason R. , Apicella Michael A. , Gibson Bradford W.
Published: August 2007

Lipopolysaccharide (LPS) is a major component of the outer membrane of gram-negative bacteria, and the lipid A region of LPS mediates stimulation of the immune system in a structure-dependent manner. Unlike the LPS of many other gram-negative bacteria, the LPS of
Francisella tularensis
isolated from in vitro cultures is not proinflammatory. This observed lack of proinflammatory prowess may reflect structural features of the lipid A, such as the number and length of the acyl chains and the single-phosphate group. To better understand this phenotype, we have begun to elucidate LPS biosynthesis in
F. tularensis
. We present complementation, mutational, and chemical data demonstrating that
F. tularensis
FTT0232c encodes a functional late acyltransferase enzyme with specificity similar to that of the
Escherichia coli
LpxL ortholog. Expression of this late acyltransferase complemented the temperature-sensitive and hypoacylated lipid A phenotypes of an
E. coli lpxL
mutant, expression of FTT0232c is increased during intracellular growth relative to that during in vitro growth, and finally, LPS obtained from a mutant of
F. tularensis
lacking FTT0232c showed an abundant triacyl lipid A species after mass spectrometric analysis, consistent with the loss of an LpxL late acyltransferase.
NONASSOCIATIVITY, DIRAC MONOPOLE AND AHARONOV–BOHM EFFECT
Authors: NESTEROV ALEXANDER I.
Published: August 2007

The Aharonov–Bohm (AB) effect for the singular string associated with the Dirac monopole carrying an arbitrary magnetic charge is studied. It is shown that the emerging difficulties in explanation of the AB effect may be removed by introducing nonassociative path-dependent wavefunctions. Our results imply that the Dirac singular string escapes detection in the AB experiment even for an arbitrary charged magnetic monopole.
TENSORIAL CURVATURE AND D-DIFFERENTIATION PART II: "PRINCIPAL" KIND AND EINSTEIN–MAXWELL THEORY
Authors: HURLEY D. J. , VANDYCK M. A.
Published: August 2007

The class of "commutative" D-operators, which was introduced in the first part of this paper, is generalized to obtain the "principal" class. It is established that principal D-operators are expressible in terms of covariant differentiation and a tensor field. Necessary and sufficient conditions are determined for the curvature operator to be tensorial, and for the scalar curvature to exist. As an application, the Einstein–Maxwell theory is recast in a new geometrical framework.
QUANTIZATION OF THE RIEMANN ZETA-FUNCTION AND COSMOLOGY
Authors: AREF'EVA I. YA. , VOLOVICH I. V.
Published: August 2007

Quantization of the Riemann zeta-function is proposed. We treat the Riemann zeta-function as a symbol of a pseudodifferential operator and study the corresponding classical and quantum field theories. This approach is motivated by the theory of p-adic strings and by recent works on stringy cosmological models. We show that the Lagrangian for the zeta-function field is equivalent to the sum of the Klein–Gordon Lagrangians with masses defined by the zeros of the Riemann zeta-function. Quantization of the mathematics of Fermat–Wiles and the Langlands program is indicated. The Beilinson conjectures on the values of L-functions of motives are interpreted as dealing with the cosmological constant problem. Possible cosmological applications of the zeta-function field theory are discussed.
Electrodeposition of NiFe Alloys in a Magnetic Field
Authors: Ispas Adriana , Bund Andreas , Matsushima Hisayoshi , Bogani Francesco , Bozzini Benedetto
Published: August 2007

The effects induced by a static magnetic field that was superimposed during the electrodeposition of NiFe alloy were investigated. It was found that the iron content of the alloy, the partial current due to hydrogen evolution reaction, the morphology and the texture of the alloys change when the magnetic field is applied perpendicular to the electric field lines. Beside changes in the morphology on a microscopic scale, no other significant effects were obtained when the magnetic field lines and the electric field lines were parallel to each other. The effects observed were considered to be induced by the additional convection generated by the interaction between the MHD convection and the natural convection.
Molecular Incorporation of Saccharin into Soft High Moment CoFe Alloys
Authors: Brankovic S. R. , Haislmaeir Ryan , Vasiljevic Natasa
Published: August 2007

Incorporation of the entire Saccharin molecules has been studied during the galvanostatic deposition of 2.45 T soft CoFe alloys. The results indicate that incorporation rate of Saccharin molecules is strongly dependent on the concentration of this additive in the plating solution. This dependence shows a pronounced maximum at Csach = 0.12 g/lit, which is the result with significant practical implications. The simple physical model is developed to describe this dependence having an excellent qualitative prediction of the experimental data. The corrosion properties and surface roughness of 2.45 T CoFe alloys are found to be strong function of Saccharin concentration in the solution i.e. Saccharin incorporation rate.
Reduction of Coercivity in Electroplated Permalloy Thin Films Utilizing a Brightening Agent
Authors: Bae Jonghak , Bang Wonbae , Hong Kimin
Published: August 2007

We have investigated the fabrication process and magnetic properties of thin Ni-Fe Permalloy films. We have added 0.2-1.0 mmol/L of an organic additive in the plating electrolyte. Comparing with the films prepared with inorganic electrolyte only, those plated with the additive produced smoother surface and smaller grains. The reduction of surface roughness and grain size resulted in lower coercivity, which is required for quality soft magnets.
Physical Properties of High Iron Nickel-Iron Films Deposited by Direct Current Plating
Authors: Sasaki Keith , Medina Jose A.
Published: August 2007

High iron (> 80%) nickel-iron (NiFe) films were electroplated via direct current from a sulfate/chloride bath. When used as the head core material in perpendicular magnetic recording (PMR) write heads, these magnetically soft, high stress, and low magnetostriction (in comparison to NiCoFe and CoFe films) NiFe electroplates were found to be an acceptable potential candidate for the first generation of PMR recording heads.
Characterization Of The film Of Ni-B Electroless on Steel S7, Through Optical Microscopy and Scanning Electron Microscopy.
Authors: Dominguez-Rios Carlos , Torres-Sanchez Roal , Aguilar-Elguezabal Alfredo
Published: August 2007

Microstructural characterization is a fundamental tool for the study of plating, since the macroscopic behavior of films can be correlated with microstructure of films. In this work we show the results of characterization of an electroless Ni-B film deposited on a steel S7; it was found that boron content was lower as immersion time on Ni-B bath increases and hardness was also lower as thickness of film increased. At interface, equiaxed growth of grains is probably induced by the high amount of nucleation sites on substrate surface. After thermal treatment, the highest hardness was near the Ni-B film-substrate interface. The thermal treatment at 400 {degree sign}C reduced the amount of equiaxed grains and induces the formation of Ni3B phase.
Directional Permeability Dependence in Electroplated Permalloy Layers
Authors: Bedenbecker Matthias , Celinski Zbigniew , Gatzen H. H.
Published: August 2007

Flux guides made of soft magnetic thin-film material are an important component of micro actuators based on electromagnetic transducer principles. One essential property of soft magnetic films is the relative permeability µr. To achieve a low magnetic resistance (reluctance), a high relative permeability µr is required. While the permeability in patterned flux guides located in the wafer plane typically can be determined rather easily (it typically is similar to the permeability of non-patterned films) the permeability in patterns with a flux perpendicular to the wafer plane quite often is unknown. However, for the magnetic behavior of the whole thin-film core it is of utmost importance. Flux guides often feature a thickness of some ten micrometers, but lateral dimensions of hundreds of micrometers or even some millimeters and therefore are subject to demagnetization effects. Therefore, any permeability measurement on patterned magnetic films has to take the influence of the flux guide geometry into account. This paper describes an approach to determine the real average relative permeability µr along the main axes, i.e. parallel and perpendicular to the wafer surface, by using special multiple probes, subjecting the probes to a Vibrating Sample Magnetometer (VSM) test to determine the apparent relative permeability µr,app of a probe, and calculating the real relative permeability µr,real by taking the demagnetization factor into account.
FeCo/Cu and FeCo/Ru Laminated Structures by Electrodeposition
Authors: Huang Qiang , Bonhote Christian , Lam J. , Romankiw Lubomyr T.
Published: August 2007

Studies were carried out on the laminated structures FeCo/Cu and FeCo/Ru prepared by two-bath plating, one-bath plating and plating-sputtering hybrid method. Zero remnant magnetization as in antiferromagnetically coupled structures made by sputtering was not achieved. A slow magnetization was observed for structures plated from two baths. A hypothesized mechanism was proposed, involving a superparamagnetic component due to the displacement and corrosion reactions. This effect is less prominent in the structures prepared with one bath plating. Lower magnetic moments were observed, probably due to the inclusion of Cu in FeCo layers as well as a displacement reaction. All the structures prepared by plating-sputtering method behave like a bulk ferromagnetic material. An increase and decrease of the magnetic moment was observed for FeCo/Cu and FeCo/Ru, respectively, probably due to the different effect on the corrosion reaction by Cu and Ru.
Concept for a Wafer Level Test System for Measuring Magnetic Film Properties
Authors: Gatzen H. H. , Dinulovic Dragan , Flick Eva , Gerdes Holger , Feindt Karsten , Eccarius Mathias
Published: August 2007

Achieving the specified magnetic properties of magnetic thin- films is a precondition for a successful wafer fabrication of magnetic thin-film devices. In many cases, these films are anisotropic, with two main axes (hard and easy) perpendicular to each other. For a wafer level measurement along these axes, a new test approach is suggested: employing two micro sensors, each one measuring along one of the two desired axes and engaging them alternatively by means of a micro actuator. This paper discusses the suggested approach and presents a design for the micro sensors and the micro actuator.
Design and Fabrication of High Anisotropy Nanoscale Bit-Patterned Magnetic Recording Medium for Data Storage Applications
Authors: Litvinov Dmitri , E Chunsheng , Parekh Vishal , Smith Darren , Rantschler James , Zhang Shishan , Donner Wolftgang , Lee T. R. , Ruchhoeft Paul , Weller Dieter , Khizroev Sakhrat
Published: August 2007

Design considerations for bit-patterned magnetic medium for next generation data storage systems is presented. (Co/Pd)N magnetic multilayers are evaluated as candidates for bit- patterned medium recording layer materials for their high and easily tunable magnetic anisotropy. Optimized patterned multilayers used in this study had coercivities in excess of 12- 14kOe. Bit patterning was accomplished using ion-beam proximity printing, a high-throughput direct write lithography where a large array of ion beamlets shaped by a stencil mask is used to write an arbitrary device pattern. It is found that the nature of magnetization reversal strongly depends on bit edge imperfections and is likely to contribute to switching field distribution.
Electrodeposition of Magnetic Co-Pd and Fe-Pd Alloys
Authors: Takata Fernanda M. , Pattanaik Gyana , Sumodjo Paulo Teng An , Zangari G.
Published: August 2007

We have prepared Co-Pd and Fe-Pd alloy films by galvanostatic electrodeposition from alkaline baths containing metal sulfates and 5-sulfosalicylic acid onto copper and titanium substrates. Both as-deposited Co-Pd and Fe-Pd alloy films were amorphous or nanocrystalline and magnetically soft. Deposition current density enables control over the film composition in a wide range. Post-deposition thermal annealing in (N2 + 5% H2) ambient was carried out to detect the formation of any chemically ordered phase and improvement in magnetic properties. The Co-Pd films after annealing were still amorphous and magnetically soft for both copper and titanium substrates. Completely different behavior was observed in the annealed Fe-Pd films on titanium substrate. After suitable annealing of the as-deposited Fe-Pd films on titanium substrates, the tetragonal L10 structure was obtained as confirmed by XRD, along with hard magnetic properties with coercivities up to 1880 Oe.
Fabrication and Operation of Magnetic Quantum-Dot Cellular Automata All Magnetic Logic
Authors: Orlov Alexei , Imre Alexandra , Ji Lili , Csaba Gyorgy , Bernstein Gary H. , Porod Wolfgang
Published: August 2007

We report the fabrication of, and demonstrate logic functionality in, networks of magnetically-coupled, nanometer-scale magnets performing binary computation in a magnetic quantum-dot cellular automata (MQCA) system. MQCA is an all-magnetic logic that offers low power dissipation and high integration density of functional elements. Basic elements of MQCA architecture such as binary wire and three input majority logic gate are demonstrated at room temperature.
Formation of Platinum films by Electrochemical Atomic Layer Deposition (ALD) via Redox Replacement of UPD: Studies of Pb UPD as a Sacrificial Metal
Authors: Vairavapandian Deepa , Stickney John L.
Published: August 2007

The development of Surface limited Redox Replacement (SLRR) for formation of Platinum nanofilms using Pb UPD is described in this paper. The SLRR involved formation of Pb UPD and its spontaneous replacement by Pt, at the open circuit potential (OCP), from a Pt cation solution. This reaction was repeated to form thicker Pt nanofilms. An electrochemical flow cell system was employed for growing the Pt nanofilms. Changes in the OCP were monitored during the exchange process, and showed that exchange of Pt for Pb was complete in less than 3 minutes. The increase in Pb deposition charge from cycle to cycle, as well as AFM images, showed the deposition was not just layer by layer, 2D, but resulted in significant roughening. An attempt at electrochemical annealing by using adsorbed I atoms was also tried, but with no positive result. Films were analyzed by EPMA, and showed nearly uniform composition across the deposit, with no significant amount of Pb present.
Preparation of the HCP Nano-Sheet Cobalt via a Green-Solvothermal Route
Authors: Yuan Ding S.
Published: August 2007

The nano-sheet cobalt has been prepared via a green- solvothermal route. The spectra of X-ray powder diffraction (XRD) prove that as-prepared cobalt is hexagonal close-packed cobalt (hcp) phase in this research. The saturated magnetization intensity (Ms), coercive force (Hc) and remanence (Br) of the hcp cobalt sheets with 59.2 nm thickness are 318 emu g-1, 199 Oe and 25 emu g-1 at 293K, respectively. The nano-size hcp cobalt with higher Ms and lower Hc is soft magnetic materials.
Electrodeposition as a Versatile Analytical and Preparation Tool
Authors: Schad Rainer , Scheck Christian , Liu Yi-Kuang , Vutukuri Srinivasulu , Hamner Robert , Kaiser Christian , Schreiter O. , Zangari G.
Published: August 2007

We present an overview of multiple applications of the versatile electro-deposition technique for magnetic thin film preparation. The technique allows excellent parameter control to produce epitaxial ferromagnetic layers on semiconductor substrates. The technique minimizes interface and bulk defects. The selectivity of electrodeposition can also be used for identification and quantification of defects and for lithography-free preparation of nanostructures.
A Novel Selective Freelayer Wet Etching Method for Magnetic Tunnel Junction-Based MRAM
Authors: O'Sullivan Eugene J.
Published: August 2007

This paper describes the development of a novel wet etch process for selective patterning of ferromagnetic freelayers, principally Permalloy, in MRAM magnetic tunnel junction (MTJ) stacks. The method uses a nonadsorbing acid, trifluoromethane sulfonic (TFMSA), as the etchant acid. Freelayer etch selectivity to the alumina tunneling barrier is achieved through the use of long-chain alkane sulfonic acid salts, e.g. sodium 1-tetradecanesulfonate. These inhibitors can increase the alumina barrier etch resistance in the TFMSA solution by up to two orders of magnitude. The importance of the reactive ion etching process used for MTJ cap layer removal prior to the wet etching step is discussed. Open circuit potential (OCP) was shown to be a powerful method for following the progress of freelayer wet etching and for evaluating alumina barrier etch inhibitors.
Structural Study of CoFeB/MgO/CoFeB Magnetic Tunnel Junctions
Authors: Tsunekawa Koji , Choi Young-Suk , Nagamine Yoshinori , Djayaprawira David D. , Watanabe Naoki , Takeuchi Takashi , Kitamoto Yoshitaka
Published: August 2007

We present the influence of post-growth annealing on crystallization process of amorphous CoFeB and tunneling magnetoresistance effect in polycrystalline CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs). The crystallization of amorphous CoFeB to bcc CoFe by annealing commences at the interface with the (001)-textured polycrystalline MgO layer. Then the bcc CoFe grows in grain-to-grain epitaxy mode by the 45{degree sign} rotation to reduce the lattice mismatch with MgO, in that the epitaxial relationship of CoFe(001)[110]//MgO(001)[100] is realized. This is suggested to be one of crucial prerequisites to obtain the giant TMR in the polycrystalline MTJs.
Fermi Level and Magnetic GaMnN Thin Films
Authors: El-Masry Nadia A. , Arkun F. Erdem , Berkman Acar , Mahrous Amr , Zavada John M. , Bedair Salah M.
Published: August 2007

Spin based electronics is an emerging field where the spin of electrons in addition to the charge of electrons is manipulated and different functionalities in devices are achieved. Developments of new materials, that are ferromagnetic at room temperature such as GaMnN, will allow us to create spin- polarized electrons which are prerequisite for progress in this field. Theory suggests that GaN when alloyed with transition metals such as Mn at low concentrations (5 % Mn) will be ferromagnetic. The growth and the origin of the magnetic property in this crystal are still under investigation. We demonstrate the growth and characterization of GaMnN films on (0001) sapphire substrates by MOCVD. We have found that the magnetization in these films correlate with the position of the Fermi level in the crystal. Moreover, changing the position of the Fermi level by co-doping changes the magnetization observed in these films . Our experiments reveal a possible mechanism of the observed magnetic property in this material system. We have also found that charge transfer across ferromagnetic and non magnetic interfaces resulted in changes in the magnetic properties
Measurement of pancreatic islet cell proliferation by heavy water labeling
Authors: Chen Songyuan , Turner Scott , Tsang Ellen , Stark Julie , Turner Holly , Mahsut Ablatt , Keifer Keri , Goldfinger Michelle , Hellerstein Marc K.
Published: August 2007

We describe a sensitive technique for measuring long-term islet cell proliferation rates in vivo in rats. Pancreatic islets were isolated and the incorporation of deuterium (2H) from heavy water (2H2O) into the deoxyribose moiety of DNA was measured by GC-MS. The results of heavy water labeling and BrdU staining were compared. The two methods were highly correlated ( r = 0.9581, P < 0.001). Based on long-term heavy water labeling, ∼50% of islet cells divided in rats between 8 and 15 wk of age. Of interest, long-term BrdU administration suppressed proliferation of islet cells significantly, but not of bone marrow cells. Physiological evidence further supported the validity of the method: older animals (24 wk old) had 60% lower islet cell proliferation rates than younger rats (5 wk old), and partial (50%) pancreatectomy increased proliferation by 20%. In addition, cholecystokinin-8 treatment significantly stimulated proliferation in pancreatectomized rats only. In summary, heavy water labeling is a quantitative approach for measuring islet cell proliferation and testing therapeutic agents.
Transient Limb Ischemia Induces Remote Preconditioning and Remote Postconditioning in Humans by a K
ATP
Channel–Dependent Mechanism
Authors: Loukogeorgakis Stavros P. , Williams Rupert , Panagiotidou Anna T. , Kolvekar Shyamsunder K. , Donald Ann , Cole Tim J. , Yellon Derek M. , Deanfield John E. , MacAllister Raymond J.
Published: August 2007

Background—

Transient limb ischemia administered before a prolonged ischemic insult has systemic protective effects against ischemia-reperfusion (IR) injury (remote ischemic preconditioning [RIPC]). It has been demonstrated that protection from IR can be achieved by brief periods of ischemia applied at a remote site during an injurious ischemic event (remote postconditioning [RPostC]). Using an in vivo model of endothelial IR injury, we sought to determine whether RPostC occurred in humans and whether it shared mechanistic similarities with RIPC.

Methods and Results—

Endothelial function was assessed by flow-mediated dilation before and after IR (20 minutes of arm ischemia followed by reperfusion). RIPC was induced by conditioning cycles of 5 minutes of ischemia and reperfusion on the contralateral arm or leg before IR. For RPostC induction, conditioning cycles were administered during the ischemic phase of IR. Oral glibenclamide was used to determine the dependence of RIPC and RPostC on K
ATP
channels. IR caused a significant reduction in flow-mediated dilation in healthy volunteers (baseline, 9.3±1.2% versus post-IR, 3.3±0.7%;
P
<0.0001) and patients with atherosclerosis (baseline, 5.5±0.6% versus post-IR, 2.3±0.5%;
P
<0.01). This reduction was prevented by RIPC (post-IR+RIPC: healthy volunteers, 7.2±0.5% [
P
<0.0001 versus post-IR]; patients, 4.5±0.3% [
P
<0.01 versus post-IR]) and RPostC (post-IR+RPostC: 8.0±0.5%;
P
<0.0001 versus post-IR). The protective effects of RIPC and RPostC were blocked by glibenclamide.

Conclusions—

This study demonstrates for the first time in humans that RPostC can be induced by transient limb ischemia and is as effective as RIPC in preventing endothelial IR injury. RIPC and RPostC share mechanistic similarities, with protection being dependent on K
ATP
channel activation. These results suggest that remote conditioning stimuli could be protective in patients with acute ischemia about to undergo therapeutic reperfusion.
β2-Microglobulin as a Biomarker in Peripheral Arterial Disease
Authors: Wilson Andrew M. , Kimura Eiichiro , Harada Randall K. , Nair Nandini , Narasimhan Balasubramanian , Meng Xiao-Ying , Zhang Fujun , Beck Kendall R. , Olin Jeffrey W. , Fung Eric T. , Cooke John P.
Published: August 2007

Background—

Peripheral arterial disease (PAD) is common but commonly unrecognized. Improved recognition of PAD is needed. We used high-throughput proteomic profiling to find PAD-associated biomarkers.

Methods and Results—

Plasma was collected from PAD patients (ankle brachial index of <0.90; n=45) and subjects with risk factors but without PAD (n=43). Plasma was analyzed with surface-enhanced laser desorption/ionization time-of-flight mass spectrometry to quantify 1619 protein peaks. The peak intensity of a 12-kDa protein was higher in PAD patients. Western blot analyses and immunoaffinity studies confirmed that this protein was β2-microglobulin (B2M). In a validation study, B2M was measured by ELISA in plasma in age- and gender-matched PAD (n=20) and non-PAD (n=20) subjects. Finally, we studied a larger cohort of subjects (n=237) referred for coronary angiography but without known PAD. Plasma B2M levels were higher in PAD patients than in non-PAD patients with coronary artery disease. Plasma B2M correlated with ankle brachial index and functional capacity. Independent predictors of PAD were diabetes mellitus, age, and the combination of B2M and C-reactive protein level.

Conclusions—

In PAD patients, circulating B2M is elevated and correlates with the severity of disease independent of other risk factors. These findings might provide a needed biomarker for PAD and new insight into its pathophysiology. Further studies in other populations are needed to confirm the utility of measuring B2M in cardiovascular disease risk assessment.
Brachial Artery Flow-Mediated Dilation and Asymmetrical Dimethylarginine in the Cardiovascular Risk in Young Finns Study
Authors: Juonala Markus , Viikari Jorma S.A. , Alfthan Georg , Marniemi Jukka , Kähönen Mika , Taittonen Leena , Laitinen Tomi , Raitakari Olli T.
Published: August 2007

Background—

Elevated asymmetrical dimethylarginine (ADMA) is a novel risk factor for atherosclerosis that may impair endothelial function by interfering with endothelial nitric oxide synthesis. To gain insight into the effects of ADMA on systemic endothelial function, we examined the association between ADMA and brachial artery flow-mediated dilation (FMD) in a large population of young adults.

Methods and Results—

Plasma ADMA and brachial FMD, as well as conventional cardiovascular risk factors, were measured in 2096 white adults aged 24 to 39 years. In univariate analysis, ADMA was inversely correlated with FMD (
r
=−0.07,
P
=0.003). The inverse association between ADMA and FMD remained significant in a multivariable regression model adjusted for age, sex, conventional cardiovascular risk factors, estimated glomerular filtration rate, and brachial artery baseline diameter (β±SE −1.56±0.62%,
P
=0.01).

Conclusions—

We conclude that elevated plasma ADMA concentrations are associated with decreased brachial FMD responses in healthy adults. These data provide evidence at the population level that ADMA levels are associated with endothelial function.