bluuebunny/crossref_metadata_2025 huggingface dataset:
Prognostic impact of DNA ploidy pattern, S‐phase fraction (SPF), and proliferating cell nuclear antigen (PCNA) in patients with primary gastric lymphoma
Authors: Belessi Chrysoula J. , Parasi Aikaterini S. , Manioudaki Helen S. , Laoutaris Nikolaos P. , Legakis Nikolaos C. , Peros Georgios Th. , Androulakis Georgios A.
Published: March 2003

Background

DNA ploidy, S‐phase fraction (SPF), and proliferating cell nuclear antigen (PCNA) are considered to be significant prognostic factors in non‐Hodgkin lymphomas. However, reports on their prognostic importance in gastric lymphoma patients are relatively lacking.

Methods

In the present study, we retrospectively studied the above‐mentioned parameters in 29 patients with primary gastric lymphoma; 11/29 had B‐low grade mucosa associated lymphoid tissue lymphoma (B‐MALT), while 18/29 had diffuse large B‐cell lymphoma (DLBCL), according to WHO classification. Proliferative activity was studied by staining against PCNA; in addition, the prognostic significance of DNA ploidy and SPF, as determined by flow cytometry, were investigated and compared to the results of the PCNA stainings.

Results

Seven out of 29 patients were found to have aneuploid tumors; DNA index values were >1 for all aneuploid lymphomas. There was no difference in DNA aneuploidy in MALT vs. DLBCL. The mean percentage of SPF was 11.4. SPF was found significantly lower in MALT vs. DLBCL (P < 0.05). The mean percentage of PCNA positive tumor cells was 52.6. PCNA protein expression was significantly lower in MALT vs. DLBCL (P < 0.0001). There was a significant positive correlation between PCNA score and SPF (P < 0.01, by Spearman analysis). DNA ploidy had no impact on survival in the present study. Both SPF and PCNA expression were important prognostic factors in the univariate analysis; however, in the multivariate analysis, the only independent prognostic factor for survival was PCNA expression.

Conclusions

These findings indicate that SPF and PCNA are significant prognostic factors in patients with primary gastric lymphomas. However, in the present study, DNA ploidy had no impact on survival in patients with primary gastric lymphomas. J. Surg. Oncol. 2003;82:247–255. © 2003 Wiley‐Liss, Inc.
Biodegradable Laminates Based on Gelatin, 2
Authors: Apostolov Anton A. , Fakirov Stoyko , Hoffmann Jürgen , Friedrich Klaus
Published: March 2003

Compression moulded laminates based on a gelatin or a blended gelatin/starch matrix reinforced by fabrics (linen or silk) were prepared. Three linen or five silk sheets with a powdered matrix between them were compression moulded at 180 °C for several minutes. In addition, cross‐linked laminates were obtained by using methylenedi(p‐phenyl) diisocyanate as a cross‐linking agent expected to obtain an improved integrity between the matrix and the reinforcing elements. In this way a total of ten uncross‐linked and cross‐linked samples differing in the type of the matrix (gelatin or gelatin/starch) and the type of the reinforcing element (linen or silk), both uncross‐linked and cross‐linked, were obtained. All samples were characterized by means of mechanical testing (Young's modulus, tensile strength, elongation at break and impact strength), as reported in Part 1 of this study. In the present Part 2, the same ten samples were artificially weathered, and changes in both the mechanical properties and the specific wear rate with aging time were followed. It was found that the majority of the mechanical parameters generally became worse with aging time; only the Young's modulus and the tensile strength remained on the same order of magnitude for all laminates. The linen reinforced laminates showed much higher values of the deformation at break, the impact strength and the wear resistance in comparison to the silk reinforced laminates. A similar tendency was found for the sliding wear tests against smooth steel counterparts. A reinforcement of gelatin or gelatin/starch with linen was much more effective in improving the laminate wear resistance than a reinforcement with silk. In addition, the abrasion resistance of neat gelatin was found to be much higher than that of the gelatin/starch blend, as evaluated by the Taber index.

Dependence of Young's modulus on aging time for the neat matrix samples (gelatin and gelatin/starch) and the compression moulded laminates reinforced with fabrics.

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Dependence of Young's modulus on aging time for the neat matrix samples (gelatin and gelatin/starch) and the compression moulded laminates reinforced with fabrics.
Simulation of Nylon 6 Polymerization in an Industrial Two‐Step VK Tubular Reactor
Authors: Wenhua Xiao , Huang Nanxun , Tang Zhilian , Filippini‐Fantoni Roberto
Published: March 2003

A commonly used nylon 6 two‐step VK tubular reactor is simulated in this work. To verify the reliability of the model, careful comparison with results obtained on different continuous plants is made. The effect of various conditions and parameters, e.g. feed composition, temperature, pressure, etc. on the product properties such as caprolactam conversion, degree of polymerization (DP), dimer, integral heat and their distribution index is studied. It is observed that the caprolactam conversion and DP of the product may be affected by various conditions in the first stage and the temperature profile at the top of the second stage, but they finally reach the equilibrium values if the residence time is long enough. The most effective way to increase DP of the product is to increase the vacuum at the top of the second stage.

CPL conversion and DP profile for pressure of tube 2: 0.032, 0.037, 0.042 mPa; other parameters as given for example A of Table 5.

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CPL conversion and DP profile for pressure of tube 2: 0.032, 0.037, 0.042 mPa; other parameters as given for example A of Table 5.
Structure‐Property Relationships of New Water‐Soluble Grafted Starches with Amphoteric Character
Authors: Zhang Li‐Ming , Chen Dan‐Qing
Published: March 2003

In an attempt to develop an environmentally friendly, multifunctional mud additive for oilfield drilling treatment, new water‐soluble grafted starches with amphoteric character were prepared by grafting the mixed monomer system of 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid (AMPS) and 2‐(dimethylamino)ethyl methacrylate (DMAEM) onto naturally occurring potato starch, and characterized by IR and composition analyses. Their structure‐property relationships with respect to the hydration suppression of the swellable clay and the control of mud rheology were studied with the help of clay hydration‐swelling test, mud rheology test, and SEM observation. It has been found that the grafting of DMAEM enhances the inhibition effectiveness of clay hydration‐swelling and that the grafting of AMPS increases the viscosity of the treated muds and the tolerance to added salt. Compared with the partially hydrolyzed polyacrylamide with a degree of hydrolysis of 16%, a typical polymeric additive used in current drilling fluids, such grafted starch with suitable grafting percentage and composition has some distinct advantages in the formulation of water‐based drilling muds.

Swelling percentage (Sp) of the clay pellets as a function of hydration time (t) in water and various sample solutions.

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Swelling percentage (Sp) of the clay pellets as a function of hydration time (t) in water and various sample solutions.
Preparation and Combustion Properties of Flame Retardant Nylon 6/Montmorillonite Nanocomposite
Authors: Hu Yuan , Wang Shaofeng , Ling Zhihua , Zhuang Yonglong , Chen Zuyao , Fan Weicheng
Published: March 2003

Flame retardant Nylon 6 (PA6)/montmorillonite (MMT) nanocomposites have been prepared using direct melt intercalation technique by blending PA6, organophilic clay and conventional fire retardants, such as the melamine cyanurate (MCA) and the combination of decabromodiphenyl oxide (DB) and antimony oxide (AO). Their morphology and combustion properties are characterized by XRD, transmission electron microscopy (TEM), UL‐94 test and Cone Calorimeter experiments. The flame retardant nanocomposites with MCA or DB and AO show lower heat release rate (HRR) peak compared to that of conventional flame retardant PA6. Meanwhile, the synergetic effect was studied between clay and DB‐AO.

TEM of PA‐n nanocomposite.

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TEM of PA‐n nanocomposite.
Differential Scanning Calorimetry Study of Blends of Poly(ethylene glycol) with Selected Fatty Acids
Authors: Pielichowski Krzysztof , Flejtuch Kinga
Published: March 2003

A series of blends of poly(ethylene glycol) (PEG) with different molecular weights with: (i) capric, (ii) lauric, (iii) myristic, (iv) palmitic or (v) stearic acid, as a thermal energy storage material, has been investigated by differential scanning calorimetry (DSC). Transition temperatures and latent heat of transition of PEG, fatty acids and their binary blends were determined since these properties are of primary importance in the design of phase change energy storage materials. The experimental results showed that it is possible to obtain homogeneous (as indicated by DSC data) polymer/fatty acid blends by mixing in the melt and subsequent solidification. The melting ranges of PEG/fatty acid systems were observed to be from 30 to 72 °C while their heat of transition lies in the range of 168–208 J · g−1. Synergistic action of the components was found for PEG 10 000/stearic acid blend – heat of transition was ca. 15 and 35% higher than for pure stearic acid and PEG, respectively. This phenomena may be explained in terms of strengthened specific interactions via hydrogen bonding leading to formation of more perfect crystalline lattice.

DSC melting and freezing curves of blends PEG/lauric acid. 1 ‐ PEG 3 400/lauric acid, 2 ‐ PEG 10 000/lauric acid, 3 ‐ PEG 20 000/lauric acid, 4 ‐ PEG 35 000/lauric acid (cooling ‐ 10 K · min−1), 5 ‐ PEG 3 400/lauric acid, 6 ‐ PEG 10 000/lauric acid, 7 ‐ PEG 20 000/lauric acid, 8 ‐ PEG 35 000/lauric acid (heating ‐ 10 K · min−1).

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DSC melting and freezing curves of blends PEG/lauric acid. 1 ‐ PEG 3 400/lauric acid, 2 ‐ PEG 10 000/lauric acid, 3 ‐ PEG 20 000/lauric acid, 4 ‐ PEG 35 000/lauric acid (cooling ‐ 10 K · min−1), 5 ‐ PEG 3 400/lauric acid, 6 ‐ PEG 10 000/lauric acid, 7 ‐ PEG 20 000/lauric acid, 8 ‐ PEG 35 000/lauric acid (heating ‐ 10 K · min−1).
SCA2 may present as levodopa‐responsive parkinsonism
Authors: Payami Haydeh , Nutt John , Gancher Steven , Bird Thomas , McNeal Melissa Gonzales , Seltzer William K. , Hussey Jennifer , Lockhart Paul , Gwinn‐Hardy Katrina , Singleton Amanda A. , Singleton Andrew B. , Hardy John , Farrer Matthew
Published: March 2003

Some kindreds with familial parkinsonism exhibit genetic anticipation, suggesting possible involvement of trinucleotide repeat expansion. Recent reports have shown trinucleotide repeat expansions in the spinocerebellar ataxia 2 (SCA2) gene in patients with levodopa‐responsive parkinsonism. We tested 136 unrelated patients with familial parkinsonism for SCA2 mutations. Two probands had borderline mutations; the rest were normal. (≤31 repeats is normal, 32–35 is borderline, ≥36 is pathogenic). The expanded allele segregated with neurological signs in one kindred. The absence of borderline mutations in the normal population, and the co‐segregation of the expanded allele with neurological signs in one kindred suggest that SCA2 mutations may be responsible for a subset of familial parkinsonism. © 2002 Movement Disorder Society
Prevalence of essential tremor in three elderly populations of central Spain
Authors: Benito‐León Julián , Bermejo‐Pareja Félix , Morales José‐Manuel , Vega Saturio , Molina José‐Antonio
Published: March 2003

Although essential tremor (ET) is considered the most prevalent adult movement disorder, the available information on its prevalence and distribution worldwide is not completely understood. We investigated the prevalence and distribution of ET in three elderly Spanish populations using a door‐to‐door, two‐phase approach. A brief screening instrument was administered on May 1, 1994 to subjects over 64 years old taken from the census of one urban municipality of Greater Madrid (quarter of Margaritas, Getafe), one urban district of Madrid (Lista), and one rural site (Arévalo county, Ávila) (N = 5,278). Study subjects were limited to those who screened positively (N = 472). To increase reliability, each patient was examined by 3 experienced neurologists, and was classified as having ET only when all 3 neurologists agreed (183 of 472). The present study was part of a large‐scale epidemiological survey of neurological diseases, and served as a baseline investigation in a 3‐year incidence study. Accordingly, 41 ET patients were identified when evaluating subjects who had screened positively for dementia, stroke, or parkinsonism, despite the fact that they had screened negatively for tremor; furthermore, 32 additional ET prevalent cases were detected when evaluating subjects who had screened positively for tremor in the second cross‐sectional study (May 1, 1997), although they had screened negatively for tremor in the first cross‐sectional study. We identified 256 persons (152 women, 104 men) with ET; of these, 87 patients (34.0%) reported having an affected relative. Two hundred and four (79.7%) of the subjects with ET were detected through this screening and had not been diagnosed previously. The prevalence of ET was 4.8% (95% CI = 4.2–5.4) for the total population; 4.6% (95% CI = 3.7–5.4) in men and 5.0% (95% CI = 4.2–5.8) in women. Age‐specific prevalence increased with advancing age for both men and women. Despite the variability in worldwide data, ET is a frequently encountered disorder in elderly people. Furthermore, as ET may be seen as a relatively benign condition, a large proportion of patients may never seek neurological attention. © 2002 Movement Disorder Society
Olfaction in neurodegenerative disorder
Authors: Hawkes Christopher
Published: March 2003

There has been an increase of interest in olfactory dysfunction since it was realised that anosmia was a common feature of idiopathic Parkinson's disease (PD) and Alzheimer‐type dementia (AD). It is an intriguing possibility that the first sign of a disorder hitherto regarded as one of movement or cognition may be that of disturbed smell sense. In this review of PD, parkinsonian syndromes, essential tremor, AD, motor neurone disease (MND) and Huntington's chorea (HC) the following observations are made: 1) olfactory dysfunction is frequent and often severe in PD and AD; 2) normal smell identification in PD is rare and should prompt review of diagnosis unless the patient is female with tremor‐dominant disease; 3) anosmia in suspected progressive supranuclear palsy and corticobasal degeneration is atypical and should likewise provoke diagnostic review; 4) hyposmia is an early feature of PD and AD and may precede motor and cognitive signs respectively; 5) subjects with anosmia and one ApoE‐4 allele have an approximate 5‐fold increased risk of later AD; 6) impaired smell sense is seen in some patients at 50% risk of parkinsonism; 7) smell testing in HC and MND where abnormality may be found, is not likely to be of clinical value; and 8) biopsy of olfactory nasal neurons shows non‐specific changes in PD and AD and at present will not aid diagnosis. © 2003 Movement Disorder Society
Globus pallidus internus deep brain stimulation for dystonic conditions: A prospective audit
Authors: Yianni John , Bain Peter , Giladi Nir , Auca Marieta , Gregory Ralph , Joint Carole , Nandi Dipankar , Stein John , Scott Richard , Aziz Tipu
Published: March 2003

In the current era of functional surgery for movement disorders, deep brain stimulation (DBS) of the globus pallidus internus (GPi) is emerging as the favoured target in the treatment of patients with dystonia. The results of 25 consecutive patients with medically intractable dystonia (12 with generalised dystonia, 7 with spasmodic torticollis, and 6 with other types of dystonia) treated with GPi stimulation are reported. Although comparisons were limited by differences in their respective neurological rating scales, chronic DBS benefited all groups, resulting in clear and progressive improvements in their condition. This study clearly demonstrates that DBS of the GPi provides amelioration of intractable dystonia. © 2002 Movement Disorder Society
Reversible reorganisation of the motor cortical representation of the hand in cervical dystonia
Authors: Thickbroom Gary W. , Byrnes Michelle L. , Stell Rick , Mastaglia Frank L.
Published: March 2003

Previous work has suggested that there may be a widespread disturbance of motor control mechanisms in patients with cervical dystonia. In the present study, we used transcranial magnetic stimulation to investigate the topography of the corticomotor projection to the abductor pollicis brevis (APB) muscle in 10 subjects with idiopathic torticollis. Threshold‐adjusted stimuli were delivered at multiple scalp sites during a low‐level voluntary contraction of the APB, and maps were generated of motor evoked potential amplitude versus scalp site. The cortical maps for the APB on the side opposite to the direction of head rotation were displaced laterally or posteriorly in all subjects and reverted to a more normal position after botulinum toxin injection of the cervical muscles in 5 subjects. The findings point to a reversible reorganisation of the corticomotor representation of the hand on the same side as the sternocleidomastoid (SCM) muscle that is involved in producing the dystonia. These results provide further evidence for the involvement of cortical centres and for a more widespread abnormality of motor control mechanisms in focal dystonia. The findings also support the notion that head turning is chiefly mediated by the hemisphere ipsilateral to the direction of the head rotation by means of a corticomotor projection to the contralateral SCM. © 2003 Movement Disorder Society
Severe forward flexion of the trunk in Parkinson's disease: Focal myopathy of the paraspinal muscles mimicking camptocormia
Authors: Schäbitz Wolf‐Rüdiger , Glatz Katharina , Schuhan Christian , Sommer Clemens , Berger Christian , Schwaninger Markus , Hartmann Marius , Hilmar Goebel Hans , Meinck Hans‐Michael
Published: March 2003

Pronounced forward flexion of the trunk, often termed camptocormia, is a typical symptom of patients with Parkinson's disease. In 4 parkinsonian patients with camptocormia, paraspinal muscles were studied by electromyography (EMG) and axial computerized tomography (CT) or magnetic resonance imaging (MRI) scans and muscle biopsy. EMG of the lumbar and thoracic paravertebral muscles showed abundant fibrillations, positive sharp waves, and bizarre high‐frequency discharges. Spinal CT and MRI scans revealed variable degrees of atrophy and fatty replacement of the thoracolumbar paraspinal muscles on both sides. No other signs of neuromuscular disease were found. Biopsy of the paraspinal muscles revealed end‐stage myopathy with autophagic vacuoles, chronic inflammatory myopathy, unspecific myopathic changes, or mitochondrial myopathy. In parkinsonian patients with pronounced forward flexion of the trunk, myopathy confined to the erector spinae muscles must be considered. © 2003 Movement Disorder Society
Higher incidence of depression preceding the onset of Parkinson's disease: A register study
Authors: Leentjens Albert F.G. , Van den Akker Marjan , Metsemakers Job F.M. , Lousberg Richel , Verhey Frans R.J.
Published: March 2003

Although case histories of depression preceding Parkinson's disease (PD) point to a possible pathophysiological relationship between these two disorders, there is as yet no epidemiological evidence to support this view. We compared the incidence of depression in patients later diagnosed with PD with that of a matched control population. Using data from an ongoing general practice‐based register study, the lifetime incidence of depressive disorder was calculated for patients until their diagnosis of PD and compared with that of a matched control population from the same register. At the time of analysis, the register held information on 105,416 people. At the time of their diagnosis of PD, 9.2% of the patients had a history of depression, compared with 4.0% of the control population (χ2 = 22.388, df = 1, P < 0.001). The odds ratio for a history of depression for these patients was 2.4 (95% CI: 2.1–2.7). We concluded that the higher incidence of depression in patients who were later diagnosed with PD supports the hypothesis of there being a biological risk factor for depression in these patients. © 2003 Movement Disorder Society
fruitless Gene is required to maintain neuronal identity in evenskipped‐expressing neurons in the embryonic CNS of Drosophila
Authors: Song Ho‐Juhn , Taylor Barbara J.
Published: March 2003

The fruitless (fru) gene acts sex‐nonspecifically in the development of the embryonic central nervous system (CNS) and has sex as well as sex‐nonspecific functions in the development of the adult CNS. In the embryo, sex‐nonspecific fru mRNAs and proteins are widely expressed during neurogenesis and present in both neurons and glia. To assess whether the fru gene played any role in fate determination of neuronal precursors and neurons, we examined the development of Eve‐positive (Eve+) GMCs and neurons in fru mutants. In fru mutant embryos in which most or all fru transcripts were eliminated, the normal complement of Eve+ neurons was present initially, but some neurons were unable to maintain their Eve‐expression. Concomitantly, a subset of Eve+ neurons also showed inappropriate expression of the glial marker, reversed polarity. In addition, neurons that normally do not express Eve became Eve+ in these fru mutants. These defects were rescued in fru mutant embryos expressing specific fru transgenes under the control of the sca‐GAL4 and elav‐GAL4 drivers. These phenotypic analyses and rescue experiments provide evidence that one of the sex‐nonspecific functions of the fru gene is the maintenance of neuronal identity rather than establishment of a neuron's initial fate. © 2003 Wiley Periodicals, Inc. J Neurobiol 55: 115–133, 2003
School‐based health centers: Opportunities and challenges for school psychologists
Authors: Meyers Adena B. , Swerdlik Mark E.
Published: March 2003

School psychologists have the potential to contribute to the development and delivery of health and mental health services through school‐based health centers (SBHCs). Possible roles for school psychologists within SBHCs are described. Factors that influence school psychologists' efforts within SBHCs are discussed, including factors such as system reforms, school system governance, importance of SBHC to stakeholders, and availability of funding. Knowledge of collaborative problem solving, effective prevention and intervention strategies, and recognition of limitations of traditional mental health programs were also identified as facilitators of the school psychologist's role in a SBHC. Factors that may impede the development of SBHCs are reviewed. These factors include definitional confusion, deemphasis on prevention, community stigma, limited resources, lack of integration and coordination of services, and an emphasis on a narrow role of providing only medical services. Additional factors discussed include the narrow role of school psychologists, space limitations, the challenge of collaboration, role strain, and lack of research on interventions within a SBHC. Strategies for overcoming barriers are suggested. © 2003 Wiley Periodicals, Inc. Psychol Schs 40: 253–264, 2003.
Promoting ecologic health resilience for minority youth: Enhancing health care access through the school health center
Authors: Clauss‐Ehlers Caroline C.C.
Published: March 2003

Ethnic minority youth experience problems in access to healthcare, yet little is known about how to enhance utilization. This article will discuss the demographic realities of children of color in the United States, with a focus on health care needs and access issues that have an enormous influence on health status. The article will consider health policy as it describes the considerable barriers to quality health care for minority youth such as a lack of a usual source of care and limited health insurance. An ecologic model is presented that incorporates cultural values and community structures into the school health center. Enhancing access and utilization through the school setting is viewed as promoting ecologic resilience in youth. © 2003 Wiley Periodicals, Inc. Psychol Schs 40: 265–278, 2003.
Professional preparation of pediatric school psychologists for school‐based health centers
Authors: Shaw Steven R.
Published: March 2003

The growth of school‐based health centers parallels the development of the subspecialty of pediatric school psychology. School psychologists have had minor roles in most school‐based health centers. In many cases, school psychologists with training in the foundation of school psychology do not have the specific skills to meet the role and function in a school‐based health center. However, there is a niche for the skills that can be provided by a school psychologist with subspecialty training in pediatric school psychology. A description of the potential roles for school psychologists in school‐based health centers is presented. The professional preparation beyond foundation school psychology training required to succeed in these roles is discussed. A detailed model for predoctoral internships and postdoctoral residencies for the professional preparation of pediatric school psychologists is presented. With this advanced level of training, school psychologists are well prepared to meet the expanded role and function required in school‐based health clinics. © 2003 Wiley Periodicals, Inc. Psychol Schs 40: 321–330, 2003.
Inelastic electron tunneling due to magnons and phonons of antiferromagnetic layered MnPSe3 semiconductors
Authors: Yamaguchi K.
Published: March 2003

Inelastic electron tunneling spectra of Pb/MnPSe3/Pb junctions are measured below liquid helium temperature in the normal state of lead under an external magnetic field. The insulating barrier of MnPSe3, an antiferromagnetic layered transition metal phosphorous triselenide, is cleaved from a single crystal along the layer. The spectra are explained by interactions between tunneling electrons and MnPSe3 antiferromagnetic magnons as well as those between tunneling electrons and MnPSe3 phonons. The contribution of MnPSe3 magnons to inelastic processes is comparable to that of MnPSe3 phonons.
Temperature dependence of the EPR spectrum of Co2+ ion in crystals Zn(BF4)2 × 6H2O
Authors: Neilo G. N. , Prokhorov A. A. , Lykin S. N. , Karnachev A. S. , Prokhorov A. D.
Published: March 2003

The study of EPR spectrum of the Co2+ ion replacing Zn2+ in crystals Zn (BF4)2 × 6H2O in a wide temperature area in the X and Q ranges is carried out. The temperature dependence of the line width is measured. The separated spin–phonon contribution to the line width allowed to determine the temperature dependence of the spin–lattice relaxation rate and to show that the main relaxation process is the Raman one. For the first time the temperature dependence of the g‐factor for an ion of the iron group is found out.
Transport characteristics of ferromagnetic single‐electron transistors
Authors: Weymann I. , Barnaś J.
Published: March 2003

Spin‐dependent electronic transport in a single‐electron transistor with ferromagnetic external electrodes and ferromagnetic or nonmagnetic central part (island) is analyzed theoretically in the sequential tunneling regime. Nonequilibrium magnetic polarization of the island due to spin accumulation (spin‐dependent chemical potential) is taken into account. The accumulation takes place when the spin relaxation time on the island is sufficiently long. The crossover from slow to fast spin relaxation limits is also analyzed. The tunnel magnetoresistance, magnetic polarization of the island, and spin polarization of the flowing current are examined as a function of the bias and gate voltages.
Modeling of melting enthalpy of organic nanowires
Authors: Liang L. H. , Li J. C. , Jiang Q.
Published: March 2003

A model is developed to interpret size‐dependent melting enthalpy of nanocrystals based on consideration of the effect of surface bond number and bond strength on cohesive energy of crystals and the corresponding liquids. The model prediction corresponds to the experimental results of organic nanowires well.
Electronic and magnetic properties of diluted magnetic semiconductors A1– xMnxTe (A = Cd, Zn) (0 ≤ x ≤ 1)
Authors: Hamedoun M. , Elachheb Zahia , Bakrim H. , Hourmatallah A. , Benzakour N. , Jorio A. , Hachimi M.
Published: March 2003

We have investigated the magnetic and electronic properties of diluted magnetic semiconductors (DMS) Cd1–xMnxTe and Zn1–xMnxTe. The magnetic phase diagrams have been determined by the replica method in the framework of the Ising model using the variational principle. The obtained results are in agreement with the experimental ones. A spin glass state has been obtained for x < xc (xc = 0.6). This phase is attributed to the randomness and the frustration of the antiferromagnetic interactions between the Mn magnetic ions arising from the topology of the DMS alloys. The sp3 semi‐empirical nearest‐neighbour tight‐binding formalism is used to compute the band structures of the above two systems in the hole range of concentration 0 ≤ x ≤ 1. The variation of the gap energy Eg with x is presented. The magnetic blueshift for x > xc is discussed in relation with the published magnetic results.
A nonparametric test for proving noninferiority in clinical trials with ordered categorical data
Authors: Munzel Ullrich , Hauschke Dieter
Published: March 2003

We consider the problem of proving noninferiority when the comparison is based on ordered categorical data. We apply a rank test based on the Wilcoxon–Mann–Whitney effect where the asymptotic variance is estimated consistently under the alternative and a small‐sample approximation is given. We give the associated 100(1−α)% confidence interval and propose a formula for sample size determination. Finally, we illustrate the procedure and possible choices of the noninferiority margin using data from a clinical trial. Copyright © 2003 John Wiley & Sons, Ltd.
Attaining optimal controls for manipulating quantum systems
Authors: Zhu Wusheng , Rabitz Herschel
Published: March 2003

This article reviews the procedures for attaining laser optimal control fields to manipulate the dynamics of quantum systems. Optimal control theory, whether implemented as a computational technique or directly in the laboratory, is the most general means to achieve precise control of quantum systems. In the case of theoretical control design, a class of monotonically convergent iteration algorithms are presented, which can reduce the computational effort involved. Implementation of optimal control field design can provide physical insight into the feasibility and mechanism of control, even for quantum systems whose Hamiltonian might contain some degree of uncertainty. Moreover, optimal quantum control fields may be directly determined in the laboratory by an analogous procedure with the molecule subject to manipulation acting as an analog computer to guide the discovery of successful controls. To facilitate this process closed‐loop iteration is set up with the loop consisting of the laser, the molecular sample, and a learning algorithm to recognize patterns in the control fields giving rise to successful experimental outcomes. Theoretical design and laboratory learning can act in tandem with each other to achieve the best control and reveal information on how the control process occurs. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Generation of finite element meshes on molecular surfaces
Authors: Laug P. , Borouchaki H.
Published: March 2003

An increasingly important part of quantum chemistry involves molecular surfaces. To model such a surface, the basic idea is to assimilate each constituting atom with a simple sphere. Surface mesh generation techniques can then be used for visualization but also for simulation, where mesh quality has a strong influence on solution accuracy. This article presents a new approach to generating quality meshes on arbitrary molecular surfaces (van der Waals, solvent‐accessible, or solvent‐excluded surfaces). First, a boundary representation (B‐rep) of the surface is obtained, i.e., a set of patches and the topological relations between them. Second, an appropriate parameterization is computed for each kind of patch and the user‐specified element sizes are converted into an isotropic metric map. Third, meshes of the parametric domains are generated with respect to an induced anisotropic metric map, using a combined advancing‐front–generalized Delaunay approach. Finally, these meshes are mapped onto the entire surface. The proposed method has been integrated within the BLMOL mesh generator and application examples are given to illustrate its capabilities. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Orthogonal polynomials of a discrete variable as expansion basis sets in quantum mechanics: Hyperquantization algorithm
Authors: De Fazio Dario , Cavalli Simonetta , Aquilanti Vincenzo
Published: March 2003

In recent years, orthogonal polynomials of a discrete variable have been widely investigated both as tools of numerical analysis for the representation of functions on grids and as the superposition coefficients that appear as matrix elements of the overlap between spherical and hyperspherical harmonics corresponding to alternative coordinate systems. This article reviews our work concerning the extension of their use to quantum mechanical problems. By exploiting both their connection with coupling and recoupling coefficients of angular momentum theory and their asymptotic relationships (semiclassic limit) with spherical and hyperspherical harmonics, a discretization procedure, the hyperquantization algorithm, has been developed and applied to the study of anisotropic interactions and of reactive scattering as a quantum mechanical n‐body problem. One of the most appealing features of this method has turned out to be a drastic reduction of memory requirements and computing time for extensive dynamic calculations as obtained by a diagonal matrix formulation of the interparticle interaction (the stereodirected representation). Use for fitting of potential energy surfaces has been also proposed and further applications have been made to stereodirected dynamics via an exact representation for the scattering matrix as well as to the characterization of molecular beam polarization. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Application of single‐particle laser desorption/ionization time‐of‐flight mass spectrometry for detection of polycyclic aromatic hydrocarbons from soot particles originating from an industrial combustion process
Authors: Zimmermann R. , Ferge T. , Gälli M. , Karlsson R.
Published: March 2003

Combustion‐related soot particles were sampled in situ from the stoker system of a 0.5 MW incineration pilot plant (feeding material was wood) at two different heights over the feed bed in the third air supply zone. The collected particles were re‐aerosolized by a powder‐dispersing unit and analyzed by a single‐particle laser desorption/ionization (LDI) time‐of‐flight mass spectrometer (aerosol‐time‐of‐flight mass spectrometry, ATOFMS). The ATOFMS instrument characterizes particles according to their aerodynamic size (laser velocimetry) and chemical composition (LDI mass spectrometry). Chemical species from the particles are laser desorbed/ionized by 266 nm Nd:YAG laser pulses. ATOFMS results on individual ‘real world’ particles in general give information on the bulk inorganic composition. Organic compounds, which are of much lower concentrations, commonly are not detectable. However, recent off‐line laser microprobe mass spectrometric (LMMS) experiments on bulk soot aerosol samples have emphasized that organic compounds can be desorbed and ionized without fragmentation in LDI experiments from black carbonaceous matrices. This paper reports the successful transfer of the off‐line results to on‐line analysis of airborne soot particles by ATOFMS. The detection of polycyclic aromatic hydrocarbons from soot particles is addressed in detail. The results are interpreted in the context of the recent LMMS results. Furthermore, their relevance with respect to possible applications in on‐line monitoring of combustion processes is discussed. Copyright © 2003 John Wiley & Sons, Ltd.
Rapid determination of orotic acid in urine by a fast liquid chromatography/tandem mass spectrometric method
Authors: Marca Giancarlo la , Casetta Bruno , Zammarchi Enrico
Published: March 2003

Quantification of orotic acid (uracil‐6‐carboxylic acid) in urine is an important tool to diagnose some inherited diseases, such as urea cycle disorder (OTCD) and hereditary orotic aciduria. New rapid analytical methods are necessary to provide high‐throughput orotic acid analyses. A new analytical method has been developed for the rapid analysis of orotic acid in urine by liquid chromatography coupled with ion spray tandem mass spectrometry (LC/MS/MS). After a sample dilution 1:20, the analysis was performed in the selected reaction monitoring mode in which orotic acid was detected through the transition m/z 155 to 111. The retention time was 3.9 min in a 4.5‐min analysis. Daily calibration between 0.5–5.0 μmol/L of orotic acid, corresponding to 10–100 μmol/L in urine before the 1:20 dilution, offered consistent linearity and reproducibility. Interassay coefficient of variance (c.v.) was 4.97% at a mean concentration of 10.99 μmol/L. The sensitivity and specificity of tandem mass spectrometry permitted a high volume of analyses of orotic acid. The sample preparation is simple, inexpensive and not time demanding. Copyright © 2003 John Wiley & Sons, Ltd.
Chemical ionization of substituted naphthalenes using tetrahydrofuran as a reagent in gas chromatography with ion trap mass spectrometry
Authors: Tzing Shin‐Hwa , Ghule Anil , Chang Jia‐Yaw , Ling Yong‐Chien
Published: March 2003

The ion/molecule reactions of nine monosubstituted naphthalene compounds in chemical ionization mass spectrometry (CI‐MS) were studied using tetrahydrofuran (THF) as CI reagent. Proton affinity factors, substituent effects and the preferred site of adduct ion attachment were examined. Good correlation was observed between proton affinity and the formation of [M]+. and [M+H]+ ions. The influence of substituents on protonation and site‐specific adduct [M+13]+ and [M+41]+ ion formation is also observed, with the cyano substituent showing the most stable [M+41]+ ion. Collision‐activated dissociation experiments were used to characterize the variety of adducts formed under CI conditions, and provided insight into product ion structures and mechanisms of dissociation and condensation during CI‐MS/MS. Copyright © 2003 John Wiley & Sons, Ltd.
Quantification of acetaldehyde released by lung cancer cells in vitro using selected ion flow tube mass spectrometry
Authors: Smith David , Wang Tianshu , Sulé‐Suso Josep , Španěl Patrik , Haj Alicia El
Published: March 2003

The production of volatile compounds from cancer cell lines in vitro has been investigated using selected ion flow tube mass spectrometry (SIFT‐MS). This technique enables on‐line quantitative analyses of the headspace above cell/medium cultures. This paper reports the discovery that acetaldehyde is released by the lung cancer cell lines SK‐MES and CALU‐1. The concentration of acetaldehyde in the headspace of the medium/cell culture was measured after 16 h incubation at 37°C and found to be proportional to the number of cancer cells in the medium (typically 108). From these data, the acetaldehyde production rates of the SK‐MES cells and the CALU‐1 cells in vitro are determined to be 1 × 106 and 1.5–3 × 106 molecules/cell/min, respectively. The potential value of this new technique in cell biology and in industrial cell biotechnology is discussed. Copyright © 2003 John Wiley & Sons, Ltd.
Comparison of conventional and enhanced mass resolution triple‐quadrupole mass spectrometers for discovery bioanalytical applications
Authors: Xu Xiaoying , Veals John , Korfmacher Walter A.
Published: March 2003

A new triple‐quadrupole mass spectrometry (MS) system with enhanced resolution capabilities has recently become available. In order to evaluate the performance of this new instrument for drug discovery assays, both the linearity and the limit of detection were compared in the positive electrospray ionization (ESI) mode with those of a conventional triple‐quadrupole instrument supplied by the same manufacturer. For these studies, spiked mouse plasma standard samples were split and assayed by each instrument, which allowed for a direct comparison of the two systems. In the unit mass resolution mode, the new mass spectrometer was found to be at least ten‐fold more sensitive than the conventional instrument. The sensitivity of the new mass spectrometer under the enhanced mass resolution mode was found to be even better by another factor of two. For the test compound, the linear dynamic range was found to be 0.05–5000 ng/mL for the new instrument as compared with 2.5–5000 ng/mL for the conventional mass spectrometer. Copyright © 2003 John Wiley & Sons, Ltd.
Theory of relative sputtering rates in GDOES
Authors: Payling Richard , Aeberhard Max , Michler Johann , Authier Cyril , Chapon Patrick , Nelis Thomas , Pitchford Leanne
Published: March 2003

A detailed theory of relative sputtering rates for glow discharge optical emission spectroscopy (GDOES) is presented for the first time. The theory suggests that such sputtering rates should be nearly independent of plasma conditions. This is supported by experimental results for r.f. GDOES under varying applied power or varying pressure. Relative sputtering rates are calculated for a range of cast irons, high‐alloy steels and zinc–aluminium alloys. Within measurement uncertainties, the calculated rates agree with measured relative sputtering rates. Copyright © 2003 John Wiley & Sons, Ltd.
XPS study of carboxylic acid layers on oxidized metals with reference to particulate materials
Authors: Johansson Elisabeth , Nyborg Lars
Published: March 2003

Low‐molecular‐weight organic additives such as stearic acid are commonly used as surface additives in powder injection moulding (PIM). It is therefore important to know how the additives interact with the surface of the powder used. In this study, such interactions are studied by means of controlled adsorption of carboxylic acids on the oxides of interest. The oxides are prepared by oxidation of flat samples of Fe, Cr, Mn and Si. Surface chemical characterization is done by means of XPS, the main approach on flat samples being a comparison of angle‐resolved analysis and the use of the Tougaard nanostructure analysis technique. Taking advantage of this comparison, the Tougaard method is then applied in the evaluation of XPS analyses of stainless‐steel powder with adsorbed stearic acid. In addition, time‐of‐flight SIMS analysis is used to verify the adsorption of stearic acid on the powder surface.

It is shown that Tougaard nanostructure analysis can be used for determining the thickness of an organic layer on particulate material. The layer thickness of adsorbed stearic acid was estimated to be ∼20 Å, corresponding to monolayer adsorption. Time‐of‐flight SIMS analysis verified the adsorption of stearic acid on the powder surface. From the XPS analysis of flat samples it was determined that the use of the metal/oxide universal cross‐section in Tougaard nanostructure analysis best described the increased background due to adsorption of carboxylic acids, and that information about molecular orientation could be gained. Copyright © 2003 John Wiley & Sons, Ltd.
SAXS study of polymer adsorption on porous ZrO2
Authors: Pikus Stanislaw , Chibowski Stanislaw , Olszewska Elżbieta , Wiśniewska Malgorzata
Published: March 2003

The small‐angle X‐ray scattering method (SAXS) has been used for the analysis of polymer adsorption on porous ZrO2. Particular attention has been paid to the adsorption of polyacrylic acid (PAA) and polyacrylamide (PAM) on the surface of porous ZrO2. It has been established that the SAXS method determines whether the polymer has penetrated the carrier's pores, and that polymers of low molecular weight create a thin transition layer on the surface of ZrO2 (understood in the context of a change in the electron density). The creation of this layer is clearly reflected in the run of SAXS curves (Porod's plot). Ruland–Vonk's method has been used to determine the thickness of the transition layer. The results are consistent with those obtained when the viscosity method was used. Copyright © 2003 John Wiley & Sons, Ltd.
Obtaining quantitative information on surface excitations from reflection electron energy‐loss spectroscopy (REELS)
Authors: Werner Wolfgang S. M.
Published: March 2003

A new analysis of reflection electron energy‐loss spectroscopy (REELS) spectra is presented. Assuming inelastic scattering in the bulk to be quantitatively understood, this method provides the distribution of energy losses in a single surface excitation in absolute units without the use of any fitting parameters. For this purpose, REELS spectra are decomposed into contributions corresponding to surface and volume excitations in two steps: first the contribution of multiple volume excitations is eliminated from the spectra and subsequently the distribution of energy losses in a single surface scattering event is retrieved. This decomposition is possible if surface and bulk excitations are uncorrelated, a condition that is fulfilled for medium‐energy electrons because the thickness of the surface scattering layer is small compared with the electron elastic mean free path. The developed method is successfully applied to REELS spectra of several materials. The resulting distributions of energy losses in an individual surface excitation are in good agreement with theory. In particular, the so‐called begrenzungs effect, i.e. the reduction of the intensity of bulk losses due to coupling with surface excitations near the boundary of a solid‐state plasma, becomes clearly observable in this way. Copyright © 2003 John Wiley & Sons, Ltd.
Impact of ageing on the distribution of platinum group elements and catalyst poisoning elements in automobile catalysts
Authors: Moldovan Mariella , Rauch Sébastien , Morrison Gregory M. , Gómez Milagros , Antonia Palacios M.
Published: March 2003

The distribution of platinum group elements (PGEs) and catalyst poisoning elements (Pb, Zn, P and S) on the surface of gasoline and diesel automobile catalysts was investigated within this study. Laser ablation–inductively coupled plasma mass spectrometry (LA–ICPMS) provides both the sensitivity and the spatial resolution required for the surface analysis of sectioned automobile catalysts, and scanning along channels reveals the distribution of longitudinal changes in PGE and catalyst poisoning elements. Changes in catalyst surface features were studied for fresh catalysts and after ageing of the catalyst up to 80 000 km for both types of catalysts studied. The PGEs in the gasoline catalyst were found to decrease at the front of the catalyst after ageing, whereas the diesel catalyst presented a more constant loss along the catalyst. The fraction of poisoning elements (Pb, P and Zn for the gasoline catalyst and P and Zn for the diesel catalyst) retained by the catalyst is distributed non‐uniformly over the length of the catalyst. This could indicate different ageing mechanisms for gasoline and diesel catalysts. Copyright © 2003 John Wiley & Sons, Ltd.