bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection of myo‐inositol trispyrophosphate in equine urine and plasma by hydrophillic interaction chromatography‐tandem mass spectrometry
Authors: Wong April S. Y. , Ho Emmie N. M. , Wan Terence S. M.
Published: February 2012

Myo‐inositol trispyrophosphate (ITPP) is a new drug capable of increasing the amount of oxygen in hypoxic tissues. Studies have shown that administration of ITPP increases the maximal exercise capacity in normal mice as well as mice with severe heart failure. The properties of ITPP make it an ideal candidate as a doping agent to enhance performance in racehorses. While there have been speculations in the horseracing industry that the covert use of ITPP is already widespread, no reported method exists for the detection of ITPP in equine biological samples. ITPP is a difficult‐to‐detect drug due to its hydrophilic nature; the complexity of equine biological matrices also adds to the problem. This paper describes for the first time a method for the detection and confirmation of ITPP in equine urine and plasma. ITPP was isolated from the sample matrices by solid‐phase extraction and the extract was analyzed by hydrophilic interaction chromatography‐tandem mass spectrometry. ITPP could be detected at low ppb levels in both fortified equine plasma and urine with good precision, fast instrumental turnaround time, and negligible matrix interferences. To our knowledge, this is the first report of a validated method for the detection and unequivocal confirmation of low levels of ITPP in any biological fluid. Copyright © 2012 John Wiley & Sons, Ltd.
Copper‐Catalyzed C–N Coupling Reactions of Nitrogen‐Rich Compounds – Reaction of Iodofurazans with s‐Tetrazinylamines
Authors: Sheremetev Aleksei B. , Palysaeva Nadezhda V. , Struchkova Marina I. , Suponitsky Kyrill Yu. , Antipin Mikhail Yu.
Published: February 2012

Access to unsymmetrical secondary dihetarylamines through the Cu(OAc)2/2‐acetylcyclohexanone catalyzed cross‐coupling of s‐tetrazinylamines with iodofurazans has been developed. The reaction displays good functional group tolerance, involving nitro, azido, and azo groups, which are critical for the construction of energetic materials. Both 3,6‐disubstituted and annelated s‐tetrazines react readily with iodofurazans to furnish the desired products.
Translation‐dependent mechanisms lead to PML upregulation and mediate oncogenic K‐RAS‐induced cellular senescence
Authors: Scaglioni Pier Paolo , Rabellino Andrea , Yung Thomas M. , Bernardi Rosa , Choi Sooyeon , Konstantinidou Georgia , Nardella Caterina , Cheng Ke , Pandolfi Pier Paolo
Published: February 2012

Expression of oncogenic K‐RAS in primary cells elicits oncogene‐induced cellular senescence (OIS), a form of growth arrest that potently opposes tumourigenesis. This effect has been largely attributed to transcriptional mechanisms that depend on the p53 tumour suppressor protein. The PML tumour suppressor was initially identified as a component of the PML‐RARα oncoprotein of acute promyelocytic leukaemia (APL). PML, a critical OIS mediator, is upregulated by oncogenic K‐RAS in vivo and in vitro. We demonstrate here that oncogenic K‐RAS induces PML protein upregulation by activating the RAS/MEK1/mTOR/eIF4E pathway even in the absence of p53. Under these circumstances, PML mRNA is selectively associated to polysomes. Importantly, we find that the PML 5′ untranslated mRNA region plays a key role in mediating PML protein upregulation and that its presence is essential for an efficient OIS response. These findings demonstrate that upregulation of PML translation plays a central role in oncogenic K‐RAS‐induced OIS. Thus, selective translation initiation plays a critical role in tumour suppression with important therapeutic implications for the treatment of solid tumours and APL.
Megalin mediates the influence of sonic hedgehog on oligodendrocyte precursor cell migration and proliferation during development
Authors: Ortega María Cristina , Cases Olivier , Merchán Paloma , Kozyraki Renata , Clemente Diego , de Castro Fernando
Published: February 2012

Oligodendrocyte precursor cells (OPCs) of the optic nerve are generated in the preoptic area, from where they migrate to colonize it entirely. Sonic hedgehog (Shh) induces the proliferation of these cells as well as influencing their migration, acting through its canonical receptor (Ptc‐1). However, the multiligand receptor megalin (or LRP‐2) is also involved in Shh‐induced OPC proliferation and migration, and thus, we have evaluated the relevance of this interaction. During the stages at which Shh influences OPC development, we found megalin to be selectively expressed by optic nerve astrocytes, whereas Ptc‐1 and Gli1 were found in OPCs. Indeed, this pattern of expression paralleled the rostral–caudal expression of the three Shh‐related molecules during the time course of plp‐dm20+‐OPC colonization. The blockage of megalin partially abolished OPC chemoattraction and fully impaired Shh‐induced proliferation. Using in vitro co‐cultures of dissociated optic nerve cells, we demonstrated that Shh was internalized by astrocytes via megalin, and sufficient Shh was subsequently released to produce the biological effects on OPCs observed in the nerve. Together, these data indicate that at least part of the influence of Shh on OPCs is mediated by megalin during optic nerve development, and that astrocytes expressing megalin transiently capture Shh to present it to OPCs and/or to control the gradient of this molecule during development. © 2012 Wiley Periodicals, Inc.
Book Reviews
Authors: Barret Robert L.
Published: February 2012

Book reviewed in this article:

Peck, M. Scott. The Road Less Traveled: A NEW Psychology of Love, Traditional Values and Spiritual Growth.
A COMPARISON BETWEEN TWO PLACEMENT PROGRAMS FOR HARD‐CORE UNEMPLOYED PERSONS
Authors: Kemp Bryan J. , Vash Carolyn L.
Published: February 2012

An exploratory placement class was conducted to teach vocational rehabilitation clients techniques of securing jobs. The results of this attempt were compared to a similar program conducted through another agency. The differences between the two programs suggest techniques that could increase the employment potential of vocational rehabilitation clients.
COUNSELING IN THE STATE EMPLOYMENT SERVICE
Authors: Krakos Mary Alice
Published: February 2012

The place and importance of counseling in State Employment Services has, in many instances, not been recognized as a necessary function of the United States Training and Employment Service (USTES) by some local office managers as well as administrators. After discussing this matter with the counselors in the Halsted office, the following article was written not to justify the existence of counseling but hopefully to show its importance.
MOTIVATIONAL INTERVENTION: THEORETICAL CONSIDERATIONS IN EMPLOYMENT COUNSELING
Authors: Vargam Lou
Published: February 2012

The function of employment counseling has benefitted from a problem analysis approach based on the concepts of vocational choice, change, and adjustment. Continued growth, however, might be facilitated by the development of a more positive point of view that includes an analysis of the motivational process that clients experience in their attempts to attain employment. If we perceive motivation as a series of stages, we can then provide ourselves with a tool by which we can explore various points where the counselor can intervene to help clients overcome resistance and frustration.
Implications of a Follow‐Up Study of School‐Leavers
Authors: JUSTICE S. MARION
Published: February 2012

Fourteen counselors in North Carolina have cooperated in a countywide project, a follow‐up study of school‐leavers. The project was successfully executed without outside help or extra financing and with only those resources available to any group of local schools. The implications of the study in terms of the need for curricular revision and vocational and educational guidance are considered here.
“Must Have Experience”
Authors: HUNT HARRY J.
Published: February 2012

To meet employer demands for experienced workers, a Baltimore high school has begun an experiment which offers work experience to students of business subjects while they are still in school. How the project operates and how it has been received by both employers and students will be of interest to all counselors.
Oakland Youth Prepared for Government Jobs
Authors: LOCKE JAMES E.
Published: February 2012

Is your school specifically preparing youth for jobs in the Civil Service? The program adopted at Oakland, California, shows how one school is preparing its students for a field in which the occupational opportunities are constantly increasing.
A Vocational Information Workshop in High School
Authors: BABCOCK CHESTER D.
Published: February 2012

A special room for counseling was described in the November, 1940, issue of the Magazine. This article tells how to set up a vocational information workshop where all pertinent material may be assembled and made available to both students and counselors. Since the required arrangements are so simple, every school might have its own workshop.
Comprehensive care for sickle cell disease immigrant patients: A reproducible model achieving high adherence to minimum standards of care
Authors: Colombatti Raffaella , Montanaro Maria , Guasti Fabiola , Rampazzo Patrizia , Meneghetti Giorgio , Giordan Marco , Basso Giuseppe , Sainati Laura
Published: February 2012

Background

Comprehensive care and advances in clinical investigations have reduced morbidity and mortality in sickle cell disease (SCD), but only a minority of children with SCD has access to comprehensive care. In Europe the majority of patients with SCD are immigrants who present barriers in accessing the health system; therefore, new evidence‐based models of comprehensive care are needed to ensure that all SCD patients receive high‐quality care, overcoming patient‐ and health system‐related barriers. We wanted to verify if addressing the specific needs of immigrant patients contributes to improving adherence.

Procedures

Linguistic, cultural, social issues were considered in organizing comprehensive care in 2006. Hospital's records were used to determine access from 2006 to 2010 and to compare adherence before and after 2006.

Results

Ninety‐four patients with SCD were enrolled in comprehensive care; 94% were first generation immigrants (81% African). Age at diagnosis was higher for children born abroad vs. children born in Italy (66.08 vs 25.36 months, P < 0.005). Since 2006, children were seen at least once a year, with 100% adherence to follow‐up appointments. Coverage increased from 26% to 97% for flu vaccination, from 80% to 92% for pneumococcus immunization, from 27% to 100% for Transcranial Doppler (TCD) screening (P < 0.001). Emergency Department access/patient/year and inpatient admissions/patient/year decreased from 2.3 to 0.98 and from 0.30 to 0.25, respectively (P < 0.001).

Conclusions

Comprehensive care can be delivered to vulnerable groups obtaining high adherence if linguistic, cultural, social issues are addressed. This model may merit assessment in other communities where immigrants represent the majority of patients. Pediatr Blood Cancer 2012; 59: 1275–1279. © 2012 Wiley Periodicals, Inc.
How to define green adjuvants
Authors: Beck Bert , Steurbaut Walter , Spanoghe Pieter
Published: February 2012

The concept ‘green adjuvants’ is difficult to define. This paper formulates an answer based on two approaches. Starting from the Organisation for Economic Cooperation and Development (OECD) definition for green chemistry, production‐based and environmental‐impact‐based definitions for green adjuvants are proposed. According to the production‐based approach, adjuvants are defined as green if they are manufactured using renewable raw materials as much as possible while making efficient use of energy, preferably renewable energy. According to the environmental impact approach, adjuvants are defined as green (1) if they have a low human and environmental impact, (2) if they do not increase active ingredient environmental mobility and/or toxicity to humans and non‐target organisms, (3) if they do not increase the exposure to these active substances and (4) if they lower the impact of formulated pesticides by enhancing the performance of active ingredients, thus potentially lowering the required dosage of active ingredients. Based on both approaches, a tentative definition for ‘green adjuvants’ is given, and future research and legislation directions are set out. Copyright © 2012 Society of Chemical Industry
TiAl Ohmic contact on GaN, in situ high or low doped or Si implanted, epitaxially grown on sapphire or silicon
Authors: Cayrel F. , Ménard O. , Yvon A. , Thierry‐Jébali N. , Brylinsky C. , Collard E. , Alquier D.
Published: February 2012

In this work, the Ti/Al Ohmic contact quality on n‐type gallium nitride (GaN) films has been studied as a function of different process parameters such as surface cleaning procedure, etching, thickness of the deposited layers or annealing conditions. GaN epilayers, with uniform doping concentration from 1 × 1016 to 5.8 × 1018 at./cm3 were grown on sapphire or silicon substrates using AlN and/or AlGaN buffer layers. Electrical characterizations were made using circular transfer length method (cTLM) patterns with a four‐probe equipment. Specific contact resistance (SCR) was then extracted from current–voltage (I–V) characteristics, for all the process conditions. Contact structures depending on experiment parameters were studied by means of (scanning) transmission electronic microscopy (STEM‐TEM). Our results reveal that process parameters such as surface treatment have a lower impact than annealing temperature or metal thickness and annealing duration. Finally, SCR values of 1 × 10−6 Ω cm2 can be reproducibly achieved. Moreover, good Ohmic contacts have been obtained on etched surfaces or on low‐doped layers implanted with Si. This low value demonstrates a good Ohmic contact and this large parameter process window is of high interest for future device fabrication based on GaN (planar or mesa structures).
Public–Private Partnerships from a Systems Perspective: A Case in the English National Health Service
Authors: Papadopoulos Thanos
Published: February 2012

Relatively little has been published in conceptualizing Public–Private Partnerships (PPP) and illustrating conflicts in PPP by using alternative perspectives. This paper takes a General Systems Theory perspective to conceptualize PPP and discusses the applicability of Dynamical Systems Theory to assist in illustrating conflicts between partners in PPP. It does so by using a case study of Lean Thinking implementation in the English National Health Service. Conflicts are conceptualized as ‘attractors’. It is argued that differences in the depth and width of these attractors illustrate the persistence or resolution of PPP conflicts. The analysis provides useful insights into illustrating conflicts in PPP and discusses the implications for management practice. Copyright © 2012 John Wiley & Sons, Ltd.
Synthesis, Characterization, Covalent Binding, and Degree of Unwinding of Platinum(II) Bipyridine Complexes
Authors: Patel Mohan , Gandhi Deepen S. , Parmar Pradhuman A. , Bhatt Bhupesh S. , Patidar Anshul P.
Published: February 2012

The complexes [Pt(3′′‐clpbpy)Cl2] (1) [3′′‐clpbpy = 4‐(3′′‐chlorophenyl)‐6‐phenyl‐2, 2′‐bipyridine], [Pt(4′′‐clpbpy)Cl2] (2) [4′′‐clpbpy = 4‐(4′′‐chlorophenyl)‐6‐phenyl‐2, 2′‐bipyridine], [Pt(3′′‐brpbpy)Cl2] (3) [3′′‐brpbpy = 4‐(3′′‐bromophenyl)‐6‐phenyl‐2, 2′‐bipyridine], and [Pt(4′′‐brpbpy)Cl2] (4) [4′′‐brpbpy = 4‐(4′′‐bromophenyl)‐6‐phenyl‐2, 2′‐bipyridine] were synthesized and characterized. The binding of the complexes with herring sperm DNA (HS DNA) was investigated by absorption titration and viscosity measurements. It was found that the complexes have ability of interaction with DNA by covalent mode. The intrinsic binding constant Kb of the complexes with HS DNA is 8.76 × 104 (1), 9.89 ×104 (2), 1.52 × 105 (3), and 2.31 × 105 (4) M–1. The slight depression in relative specific viscosity was observed, which also attributes to covalent binding of complexes with DNA bases. Gel electrophoresis assay demonstrated the ability of the complexes to unwind negatively supercoiled pUC19 plasmid by 14° (1), 13° (2), 13° (3), and 11° (4). The in vitro cytotoxic property of the synthesized metal complexes was also carried out against brine shrimp bioassay.
Silicon‐Containing Explosives: Syntheses and Sensitivity Studies of (Azidomethyl)‐, Bis(azidomethyl)‐, and Tris(azidomethyl)silanes
Authors: Klapötke Thomas M. , Krumm Burkhard , Nieder Anian , Richter Oliver , Troegel Dennis , Tacke Reinhold
Published: February 2012

A series of (azidomethyl)silanes [Me3SiCH2N3 (1b),Me2Si(CH2N3)2 (2b), MeSi(CH2N3)3 (3b), (CH2)4Si(CH2N3)2 (4b), and (CH2)5Si(CH2N3)2 (5b)] was synthesized, starting from the corresponding (chloromethyl)silanes 1a–3a or (iodomethyl)silanes 4a and 5a. Compounds 1b–5b were characterized by NMR, IR, and Raman spectroscopy. The thermal stabilities of the (azidomethyl)silanes 1b–5b were investigated by DSC, and their impact and friction sensitivities were measured with standard BAM methods. According to these studies, the tris(azidomethyl)silane 3b has to be classified as an extremely sensitive compound.
Clinical study of ammonium acid urate urolithiasis
Authors: Chou Yii‐Her , Huang Chun‐Nung , Li Wei‐Ming , Huang Shu‐Pin , Wu Wen‐Jeng , Tsai Chia‐Chun , Chang Ai‐Wen , Chen Szu‐Miao , Lin Yu‐Ling , Lin Yi‐Pin
Published: February 2012

Ammonium acid urate (AAU) urolithiasis is a rare condition; however, it is endemic in some countries, with an especially high incidence in Asia. This study was conducted to investigate the special presentation of patients with AAU urolithiasis in Taiwan. Reports of 3457 stones were retrospectively reviewed from January 2005 to January 2010 and 25 patients with urinary stones (0.7%) containing AAU crystals were identified. The clinical and biochemical presentation of all stones were compared to evaluate the specific comorbidities of AAU stones. AAU stones were observed in 11 males (44%) and 14 females (56%) with a mean age of 60.60 ± 16.81 years and mean body mass index of 25.55 ± 3.73 kg/m2. AAU stones were frequently observed in the bladder (44%) and they were significantly larger (mean size 1.90 cm) than the non‐AAU stones (mean size 1.22 cm). Other significant comorbidities of AAU stones included chronic kidney disease (CKD) (60%), urinary tract infections (UTIs) (52%), irritable bowel syndrome (IBS) (36%), and gout (28%). In addition, there were also three patients with coexisting urothelial carcinoma (12%) in the AAU‐stone group. Patients with AAU urolithiasis were predominantly female, older in age, had increased bladder presentation, larger stones and a high percentage of coexisting CKD, UTIs, IBS, gout, and even urothelial carcinoma. Therefore, it is important for clinicians to evaluate and protect renal function in patients with AAU urolithiasis.
Lagrangian subbundles of symplectic bundles over a curve
Authors: CHOE INSONG , HITCHING GEORGE H.
Published: February 2012

A symplectic bundle over an algebraic curve has a natural invariantsLagdetermined by the maximal degree of its Lagrangian subbundles. This can be viewed as a generalization of the classical Segre invariants of a vector bundle. We give a sharp upper bound onsLagwhich is analogous to the Hirschowitz bound on the classical Segre invariants. Furthermore, we study the stratifications induced bysLagon moduli spaces of symplectic bundles, and get a full picture for the case of rank four.
On the set of zero coefficients of a function satisfying a linear differential equation
Authors: BELL JASON P. , BURRIS STANLEY N. , YEATS KAREN
Published: February 2012

LetKbe a field of characteristic zero and suppose thatf:→Ksatisfies a recurrence of the form\[ f(n) = \sum_{i=1}^d P_i(n) f(n-i), \]fornsufficiently large, whereP1(z),. . .,Pd(z) are polynomials inK[z]. Given thatPd(z) is a nonzero constant polynomial, we show that the set ofn∈for whichf(n) = 0 is a union of finitely many arithmetic progressions and a finite set. This generalizes the Skolem–Mahler–Lech theorem, which assumes thatf(n) satisfies a linear recurrence. We discuss examples and connections to the set of zero coefficients of a power series satisfying a homogeneous linear differential equation with rational function coefficients.
Precessional states in a laboratory model of the Earth's core
Authors: Triana S. A. , Zimmerman D. S. , Lathrop D. P.
Published: February 2012

A water‐filled three‐meter diameter spherical shell, geometrically similar to the Earth's core, shows precessionally forced flows. The precessional torque is supplied by the daily rotation of the laboratory by the Earth. We identify the precessionally forced flow to be primarily the spin‐over inertial mode, i.e., a uniform vorticity flow whose rotation axis is not aligned with the sphere's rotation axis. A systematic study of the spin‐over mode is carried out, showing that the amplitude depends on the ratio of precession to rotation rates (the Poincaré number), in marginal qualitative agreement with Busse's (1968) laminar theory. We find its phase differs significantly though, likely due to topographic effects. At high rotation rates, free shear layers are observed. Comparison with previous computational studies and implications for the Earth's core are discussed.
Automatic geomorphic feature extraction from lidar in flat and engineered landscapes
Authors: Passalacqua Paola , Belmont Patrick , Foufoula‐Georgiou Efi
Published: February 2012

High‐resolution topographic data derived from light detection and ranging (lidar) technology enables detailed geomorphic observations to be made on spatially extensive areas in a way that was previously not possible. Availability of this data provides new opportunities to study the spatial organization of landscapes and channel network features, increase the accuracy of environmental transport models, and inform decisions for targeting conservation practices. However, with the opportunity of increased resolution topographic data come formidable challenges in terms of automatic geomorphic feature extraction, analysis, and interpretation. Low‐relief landscapes are particularly challenging because topographic gradients are low, and in many places both the landscape and the channel network have been heavily modified by humans. This is especially true for agricultural landscapes, which dominate the midwestern United States. The goal of this work is to address several issues related to feature extraction in flat lands by using GeoNet, a recently developed method based on nonlinear multiscale filtering and geodesic optimization for automatic extraction of geomorphic features (channel heads and channel networks) from high‐resolution topographic data. Here we test the ability of GeoNet to extract channel networks in flat and human‐impacted landscapes using 3 m lidar data for the Le Sueur River Basin, a 2880 km2 subbasin of the Minnesota River Basin. We propose a curvature analysis to differentiate between channels and manmade structures that are not part of the river network, such as roads and bridges. We document that Laplacian curvature more effectively distinguishes channels in flat, human‐impacted landscapes compared with geometric curvature. In addition, we develop a method for performing automated channel morphometric analysis including extraction of cross sections, detection of bank locations, and identification of geomorphic bankfull water surface elevation. Using the slope plotted along each channel‐floodplain cross section, we demonstrate the ability to identify and measure the height of river banks and bluffs. Finally, we present an example that demonstrates how extracting such features automatically is important for modeling channel evolution, water and sediment transport, and channel‐floodplain sediment exchange.
Electron-spin-resonance study of Y-doped Nd0.7Sr0.3MnO3 ceramics
Authors: Phan The-Long , Zhang Y. D. , Yu S. C. , Khiem N. V. , Phuc N. X.
Published: February 2012

We have used electron spin resonance (ESR) spectroscopy to investigate spin dynamics of Mn3+ and Mn4+ ions in (Nd1−xYx)0.7Sr0.3MnO3. Experimental data reveal that ferromagnetic (FM) resonance lines at temperatures T < Tmin become symmetrical-single lines in the Lorentzian shape as T ≥ Tmin, where Tmin is the temperature corresponding to the narrowest ESR linewidth. The temperature dependence of the resonant position above Tmin exhibits the presence of a spin-orbit interaction in addition to the spin-spin interaction. Based on one-phonon relaxation, the ESR linewidth versus temperature, ΔH(T), can be described by a linear function of ΔH(T) = A + BT. Also, the ESR intensity versus temperature, I(T), obeys an exponential function of I(T)=I0exp(Ea/kBT). It has been revealed that the coexistence of FM and anti-FM interactions with different strengths directly influences ESR spectra of (Nd1−xYx)0.7Sr0.3MnO3 as varying the Y content. This makes resonant spectra of Nd-based manganites different from La-based ones.
An efficient vector Preisach hysteresis model based on a novel rotational operator
Authors: Sutor Alexander , Kallwies Jan , Lerch Reinhard
Published: February 2012

The vectorial modeling of hysteresis phenomena is an important task with respect to precise numerical simulation of ferromagnetic materials. Many vector models are based on extended Preisach models. Approaches are known where the scalar Preisach models are defined in different space directions and the results are calculated by summation or integration. Within this approach, we suggest a Preisach model that uses only one Preisach plane, but an additional rotational plane. This rotational plane practically defines a direction for each Preisach element. Therefore, this operator can be evaluated in a very efficient way.
Instability of the ferromagnetic ground state in Lu2Fe17−XMnX [x = 0.5, 0.7]
Authors: Arnold Z. , Kuchin A. , Kamarad J.
Published: February 2012

The magnetic properties of polycrystalline Lu2Fe16.5Mn0.5 and Lu2Fe16.3Mn0.7 compounds have been studied under hydrostatic pressure up to 10 kbar in the temperature range of 5–300 K and at magnetic fields up to 5 T. The Lu2Fe16.3Mn0.7 compound is in the ferromagnetic (FM) state, and the Lu2Fe16.5Mn0.5 is in the FM state at low temperatures and in the antiferromagnetic state at high temperatures at ambient pressure. We have revealed that the FM state is very sensitive to volume changes and even moderate pressure is sufficient to complete its suppression. The critical pressures are 4 kbar for Lu2Fe16.5Mn0.5 and 7 kbar for Lu2Fe16.3Mn0.7. The suppression of the FM ground state is observed at practically the same volume of the elementary cell. The pressure induced Néel temperature, TN, of both compounds decreases with increasing pressure, dTN/dp = −2.5 K/kbar and dTN/dp = −3.4 K/kbar, for Lu2Fe16.5Mn0.5 and Lu2Fe16.3Mn0.7, respectively. The remarkable strengthening of the FM ground state by the Mn substitution and its total suppression by external pressure can mainly be attributed to a subtle competition of positive and negative local direct exchange interactions between Fe atoms located at inequivalent structural sites. These interactions are strongly dependent on the interatomic Fe-Fe distances.
The phase transition of ɛ-InxFe2−xO3 nanomagnets with a large thermal hysteresis loop (invited)
Authors: Yamada Kana , Tokoro Hiroko , Yoshikiyo Marie , Yorinaga Takenori , Namai Asuka , Ohkoshi Shin-ichi
Published: February 2012

A large thermal hysteresis loop was observed in the phase transition on rod-shaped ɛ-InxFe2−xO3 (x ∼ 0.04) nanomagnets. The width of the thermal hysteresis loop, ΔT, increased with increasing rod length (l), i.e., ΔT = 6 K (l = 25 nm), 14 K (40 nm), 25 K (80 nm), and 47 K (170 nm). The observed ΔT value of 47 K is one of the largest values among insulating ferromagnetic materials. The thermal hysteresis loops were analyzed by the Slichter and Drickamer model, and the results showed that the transition enthalpy and entropy do not change. However, the elastic interaction parameter between the transition sites increases with an increasing l value. Maybe the correlation length of a propagating phonon due to elastic interaction competes with the rod length of the samples, causing the rod-length dependence of the thermal hysteresis loop.
Rheological, optical, and thermal characterization of temperature-induced transitions in liquid crystal ferrosuspensions
Authors: Diestra-Cruz Heberth , Rinaldi Carlos , Acevedo Aldo
Published: February 2012

Liquid crystal ferrosuspensions (LCFs) were obtained by inclusion of magnetic microparticles in a nematic liquid crystal (NLC) at mass fractions of up to 20%. The phase transition of the NLC promotes the formation of a space filling particle network and an enhancement of the mechanical properties. Polarized optical microscopy (POM) and differential scanning calorimetry were used to study microparticle network formation. POM images show that an anisotropic particle structure formed when an external magnetic field was applied, whereas a quasihomogeneous cellular network is obtained in the absence of the field. A jump in the viscoelastic moduli at the isotropic-nematic transition temperature of the NLC was observed for all particle concentrations and applied magnetic fields. Experimental results also showed that the rheological response of the LCFs increased with magnetic field and tend to saturate at high fields. A linear relation between the particle mass fraction and the saturation value of the storage modulus was found.
Beam optics in a MeV-class multi-aperture multi-grid accelerator for the ITER neutral beam injector
Authors: Kashiwagi M. , Taniguchi M. , Umeda N. , de Esch H. P. L. , Grisham L. R. , Boilson D. , Hemsworth R. S. , Tanaka M. , Tobari H. , Watanabe K. , Inoue T.
Published: February 2012

In a multi-aperture multi-grid accelerator of the ITER neutral beam injector, the beamlets are deflected due to space charge repulsion between beamlets and beam groups, and also due to magnetic field. Moreover, the beamlet deflection is influenced by electric field distortion generated by grid support structure. Such complicated beamlet deflections and the compensations have been examined utilizing a three-dimensional beam analysis. The space charge repulsion and the influence by the grid support structure were studied in a 1/4 model of the accelerator including 320 beamlets. Beamlet deflection due to the magnetic field was studied by a single beamlet model. As the results, compensation methods of the beamlet deflection were designed, so as to utilize a metal bar (so-called field shaping plate) of 1 mm thick beneath the electron suppression grid (ESG), and an aperture offset of 1 mm in the ESG.
Rhenium ion beam for implantation into semiconductors
Authors: Kulevoy T. V. , Gerasimenko N. N. , Seleznev D. N. , Fedorov P. А. , Temirov A. A. , Alyoshin M. E. , Kraevsky S. V. , Smirnov D. I. , Yakushin P. E. , Khoroshilov V. V.
Published: February 2012

At the ion source test bench in Institute for Theoretical and Experimental Physics the program of ion source development for semiconductor industry is in progress. In framework of the program the Metal Vapor Vacuum Arc ion source for germanium and rhenium ion beam generation was developed and investigated. It was shown that at special conditions of ion beam implantation it is possible to fabricate not only homogenous layers of rhenium silicides solid solutions but also clusters of this compound with properties of quantum dots. At the present moment the compound is very interesting for semiconductor industry, especially for nanoelectronics and nanophotonics, but there is no very developed technology for production of nanostructures (for example quantum sized structures) with required parameters. The results of materials synthesis and exploration are presented.
Wide aperture permanent magnet solenoid
Authors: Hoff B. W. , Chen C. H. , Horwath J. C. , Haworth M. D. , Mardahl P. J. , Heidger S. L.
Published: February 2012

Various configurations of rare earth permanent magnet solenoids with a large bore were simulated using finite element computer modeling. The configuration effect on the axial field, Bz, and its uniformity, ΔBz, was analyzed. The magnetic orientation of individual segments and the aspect-ratio of the solenoid have a significant effect on Bz and ΔBz. Two-layered configurations assembled with trapezoidal or arc segments result in a more uniform Bz compared to configurations assembled with five-faced polyhedrons. The two-layered configuration also has the advantage of easier fabrication. A permanent magnet solenoid prototype, based on the two-layered arc segment configuration and built using Nd-Fe-B magnets, was experimentally tested. The solenoid was designed to have a length to inner diameter ratio of approximately 5:3 and a peak axial field magnitude of 1.8 kGauss. Experimental measurements agree with simulation predictions to within < 5%.
Synthesis and characterization of Nd4+xFe72Co5Ga2B17−xnanocomposite ribbons
Authors: Brandes Matthew C. , Daniil Maria , Willard Matthew A.
Published: February 2012

A series of alloys with compositions of Nd4 + xFe72Co5Ga2B17−x, where x = 0–10, were prepared by rapid solidification. Annealing the as-spun alloys above primary crystallization (Tx1) formed nanocomposite ribbons. While x-ray diffraction measurements showed the annealed alloys to be nanocrystalline, the phases present in each alloy were found to vary with Nd content. The alloys with x = 0, 7.5, and 10 contained a majority fraction of the Nd2Fe14B phase, along with Fe3B, α-Fe, and/or Nd2Fe23B3 phases. These alloys showed room temperature coercivities and remanent magnetizations of 199, 446, and 1034 kA/m and 120, 82, and 70 A m2/kg, respectively. The x = 5 and 7.5 samples were primarily made up of Nd2Fe23B3, and therefore, showed little coercivity. At elevated temperatures, the presence of Co and Ga were found to increase the coercivity of the Nd2Fe14B phase.
Dynamical changes of ion current distribution for a Penning discharge source using a Langmuir probe array
Authors: Li M. , Xiang W. , Xiao K. X. , Chen L.
Published: February 2012

A paralleled plate electrode and a 9-tip Langmuir probe array located 1 mm behind the extraction exit of a cold cathode Penning ion source are employed to measure the total current and the dynamical changes of the ion current in the 2D profile, respectively. Operation of the ion source by 500 V DC power supply, the paralleled plate electrode and the Langmuir probe array are driven by a bias voltage ranging from −200 V to 200 V. The dependence of the total current and the dynamical changes of the ion current in the 2D profile are presented at the different bias voltage. The experimental results show that the distribution of ion current is axial symmetry and approximate a unimodal distribution.
Electrostatic plasma lens for focusing negatively charged particle beams
Authors: Goncharov A. A. , Dobrovolskiy A. M. , Dunets S. M. , Litovko I. V. , Gushenets V. I. , Oks E. M.
Published: February 2012

We describe the current status of ongoing research and development of the electrostatic plasma lens for focusing and manipulating intense negatively charged particle beams, electrons, and negative ions. The physical principle of this kind of plasma lens is based on magnetic isolation electrons providing creation of a dynamical positive space charge cloud in shortly restricted volume propagating beam. Here, the new results of experimental investigations and computer simulations of wide-aperture, intense electron beam focusing by plasma lens with positive space charge cloud produced due to the cylindrical anode layer accelerator creating a positive ion stream towards an axis system is presented.
Structure and magnetism of nanocrystalline and epitaxial (Mn,Zn,Fe)3O4 thin films
Authors: Alaan U. S. , Wong F. J. , Grutter A. J. , Iwata-Harms J. M. , Mehta V. V. , Arenholz E. , Suzuki Y.
Published: February 2012

Nanocrystalline (NC) textured Mn0.5Zn0.6Fe1.9O4 (MZFO) films, grown at room temperature on both isostructural and non-isostructural substrates, show magnetization values significantly suppressed from epitaxial MZFO films. X-ray absorption spectroscopy and x-ray magnetic circular dichroism measurements indicate larger ratios of Fe3+ to Fe2+ ions on the tetrahedral sites in the NC films compared to the epitaxial films. The magnetization loops of the NC films are shifted by 200−400 Oe at low temperatures. No such effect is observed in the epitaxial films. We hypothesize that the presence of a more structurally disordered, possibly magnetically frustrated, matrix exchange biases the crystalline regions.
Dielectric and magnetic properties of Y3−xTbxFe5O12 ferrimagnets
Authors: Siao Yu-Jhan , Qi Xiaoding , Lin Chun-Rong , Huang Jung-Chun-Andrew
Published: February 2012

Y3−xTbxFe5O12 (x = 0−3) were prepared by the solid state reaction at 1350 °C. X-ray diffraction confirmed the obtained samples of a pure garnet phase. The dielectric responses were investigated over a wide frequency and temperature range. Two large, step-like increases of dielectric constants were observed at 20–100 °C and 170–270 °C, respectively. Thermal activation of the polarons related to Fe2+ was responsible for the observed dielectric behaviors. The Fe2+/Fe3+ hopping process was faster in Tb3Fe5O12 than in Y3Fe5O12. The saturation magnetization versus temperature measurements revealed the existence of a compensation point for all Y3−xTbxFe5O12 with x > 0, owing to the cancellation of net Fe3+ moments by Tb3+. The compensation temperature fell from 256 K at x = 3 to below 77 K at x = 1, because the reduced moment by the Tb3+ number reduction had to be supplemented by the increased Tb3+ interaction at lower temperature.
Effect of interface alloying and band-alignment on the Auger recombination of heteronanocrystals
Authors: Climente J. I. , Movilla J. L. , Planelles J.
Published: February 2012

We report a numerical study of the effect of interface alloying and band alignment on the Auger recombination processes of core/shell nanocrystals. Smooth interfaces are found to suppress Auger recombination, the strength of the suppression being very sensitive to the core size. The use of type-II structures constitutes an additional source of suppression, especially when the shell confines electrons rather than holes. We show that “magic” sizes leading to negligible Auger recombination [Cragg and Efros, Nano Letters 10, 313 (2010)] should be easier to realize experimentally in nanocrystals with extended interface alloying and wide bandgap.
Can orbital-free density functional theory simulate molecules?
Authors: Xia Junchao , Huang Chen , Shin Ilgyou , Carter Emily A.
Published: February 2012

Orbital-free density functional theory (OFDFT), with its attractive linearly scaling computation cost and low prefactor, is one of the most powerful first principles methods for simulating large systems (∼104–106 atoms). However, approximating the electron kinetic energy with density functionals limits the accuracy and generality of OFDFT compared to Kohn-Sham density functional theory (KSDFT). In this work, we test whether the Huang-Carter (HC) kinetic energy density functional (KEDF), which contains the physics to properly describe covalently bonded semiconductor materials, can also be used to describe covalent bonds in molecules. In particular, we calculate a variety of homonuclear diatomic molecules with the HC functional within OFDFT. The OFDFT bond dissociation energy, equilibrium bond length, and vibrational frequency of these dimers are in remarkably good agreement with benchmark KSDFT results, given the lack of orbitals in the calculation. We vary the two parameters λ (controlling the reduced density gradient contribution to the nonlocal kernel) and β (the exponent of the density in the nonlocal term) present in the HC KEDF and find that the optimal λ correlates with the magnitude of the highest occupied molecular orbital - lowest unoccupied molecular orbital energy gap. Although the HC KEDF represents a significant improvement over previous KEDFs in describing covalent systems, deficiencies still exist. Despite the similar overall shape of the KSDFT and OFDFT ground state electron densities, the electron density within the bonding region is still quite different. Furthermore, OFDFT is not yet able to give reasonable description of magnetic states. The energy orderings of the triplet and singlet states of Si2 and Al family dimers are not consistent with KSDFT or experimental results and the spin polarization distributions also differ widely between the two theories.
Rank reduction for the local consistency problem
Authors: Chen Jianxin , Ji Zhengfeng , Klyachko Alexander , Kribs David W. , Zeng Bei
Published: February 2012

We address the problem of how simple a solution can be for a given quantum local consistency instance. More specifically, we investigate how small the rank of the global density operator can be if the local constraints are known to be compatible. We prove that any compatible local density operators can be satisfied by a low rank global density operator. Then we study both fermionic and bosonic versions of the N-representability problem as applications. After applying the channel-state duality, we prove that any compatible local channels can be obtained through a global quantum channel with small Kraus rank.
On the mechanism for edge localized mode mitigation by supersonic molecular beam injection
Authors: Rhee T. , Kwon J. M. , Diamond P. H. , Xiao W. W.
Published: February 2012

We construct a diffusive, bi-stable cellular automata model to elucidate the physical mechanisms underlying observed edge localized mode (ELM) mitigation by supersonic molecular beam injection (SMBI). The extended cellular automata model reproduces key qualitative features of ELM mitigation experiments, most significantly the increase in frequency of grain ejection events (ELMs), and the decrease in the number of grains ejected by these transport events. The basic mechanism of mitigation is the triggering of small scale pedestal avalanches by additional grain injection directly into the H-mode pedestal. The small scale avalanches prevent the gradient from building-up to marginality throughout the pedestal, thus avoiding large scale transport events which span the full extent of that region. We explore different grain injection parameters to find an optimal SMBI scenario. We show that shallow SMBI deposition is sufficient for ELM mitigation.
Detecting ssDNA at single-nucleotide resolution by sub-2-nanometer pore in monoatomic graphene: A molecular dynamics study
Authors: Qiu Hu , Guo Wanlin
Published: February 2012

Obtaining a sequence-based signal at a resolution of single nucleotide during the passage of a DNA strand through nanopores remains a challenging problem. Here, we demonstrate by molecular dynamics simulations that the single-base resolution detection can be realized by pulling a single-stranded DNA through graphene nanopores with diameters down to ∼1 nm. By simply monitoring and analyzing the peak values of the pulling force profile, each nucleotide in the DNA strand can be identified and characterized, except for cytosine and thymine which remain indistinguishable. This intriguing character through narrow nanopores should help realize the low-cost and time-efficient DNA sequencing.
On the Aharonov-Casher system and the Landau-Aharonov-Casher system confined to a two-dimensional quantum ring
Authors: Bakke K. , Furtado C.
Published: February 2012

We study the quantum dynamics of a neutral particle in the Aharonov-Casher system and in the Landau-Aharonov-Casher system confined to a two-dimensional quantum ring, a quantum dot, and a quantum anti-dot potentials described by the Tan-Inkson model [W.-C. Tan and J. C. Inkson, Semicond. Sci. Technol. 11, 1635 (1996)]10.1088/0268-1242/11/11/001. We show, in the Aharonov-Casher system, that bound states can be achieved when the neutral particle is confined to the two-dimensional quantum ring and the quantum dot and discuss the appearance of persistent currents. In the Landau-Aharonov-Casher system, we show that bound states can be achieved when the neutral particle is confined to the quantum anti-dot, quantum dot, and the two-dimensional quantum ring, but there are no persistent currents.
Micronucleus formation induced by dielectric barrier discharge plasma exposure in brain cancer cells
Authors: Kaushik Nagendra K. , Uhm Hansup , Ha Choi Eun
Published: February 2012

Induction of micronucleus formation (cytogenetic damage) in brain cancer cells upon exposure of dielectric barrier discharge plasma has been investigated. We have investigated the influence of exposure and incubation times on T98G brain cancer cells by using growth kinetic, clonogenic, and micronucleus formation assay. We found that micronucleus formation rate directly depends on the plasma exposure time. It is also shown that colony formation capacity of cells has been inhibited by the treatment of plasma at all doses. Cell death and micronucleus formation are shown to be significantly elevated by 120 and 240 s exposure of dielectric barrier discharge plasma.
Low-temperature magnetization curves of anisotropic ferrimagnets
Authors: Kuz’min M. D.
Published: February 2012

Anisotropic ferrimagnets—unlike isotropic ones—exhibit a rich variety of shapes of magnetization curves. The possibilities are analyzed in an exhaustive fashion within a model with second-order anisotropy on both sublattices, limited to low temperatures and high-symmetry orientations of the applied magnetic field. It is important to discriminate between ferrimagnets with grossly unequal sublattices (when the moments differ by a factor of 2 or more) and those whose sublattice moments are relatively close, i.e., differ by less than a factor of 2. In the former case, as many as 10 different curve shapes are possible; in the latter case, only 9. For a given compound and field direction, the shape is determined by the system’s locus in the coordinate plane of reduced anisotropy parameters. For any ratio of the sublattice moments, such a diagram is obtainable by means of analytic expressions.
Low leakage current in metal-insulator-metal capacitors of structural Al2O3/TiO2/Al2O3 dielectrics
Authors: Woo Jong-Chang , Chun Yoon-Soo , Joo Young-Hee , Kim Chang-Il
Published: February 2012

Metal–insulator–metal (MIM) capacitors with Al2O3/TiO2/Al2O3 (ATA) dielectrics were fabricated and investigated. At 0 V and frequencies of 100 kHz and 1 MHz, the MIM capacitors with ATA (3/20/3 nm) and ATA (6/20/6 nm) thin films had low leakage current densities of approximately 5.2 × 10−13 and 1.5 × 10−13 A/cm2, respectively, and high capacitance densities of ∼19.48 and ∼20.13 fF/μm2, respectively. The frequency dispersion effect for these MIM capacitors was very small. The electrical transport mechanism, which is the device conduction mechanism, was determined for the varying structures of MIM capacitors.
Impact of structural transitions on electron transport at LaAlO3/SrTiO3 heterointerfaces
Authors: Schoofs Frank , Egilmez Mehmet , Fix Thomas , MacManus-Driscoll Judith L. , Blamire Mark G.
Published: February 2012

We have studied conductive LaAlO3/SrTiO3 heterostructures deposited at different oxygen pressures. Photoluminescence spectra confirm the presence of a significant amount of oxygen vacancies in samples deposited at low oxygen pressures. Power law fitting of resistance versus temperature measurements reveals fundamental characteristics of the conduction mechanism at the interface. A distinct non-Fermi-liquid behavior is observed for samples grown in higher oxygen pressure, which give two-dimensionally confined conducting interfaces, whereas characteristic electron-electron scattering is observed for samples grown in lower oxygen pressures, as seen in bulk doped SrTiO3 (i.e., oxygen deficient SrTiO3). Transitions between different conduction modes occur throughout the studied temperature range (10–270 K) as a result of structural transformations in the near-surface region of the SrTiO3.