bluuebunny/crossref_metadata_2025 huggingface dataset:
Spectroelectrochemical Study of N‐Substituted Phenoxazines as Electrochemical Labels of Biomolecules
Authors: Kulys Juozas , Vidziunaite Regina , Janciene Regina , Palaima Algis
Published: September 2006

The electrochemical conversion of N‐substituted phenoxazines (NSP's) bearing a CH2CH2X substitute (where XOH, COOH, CH2NH2, CH2SO3H, CH2NHCOR) was investigated using cyclic voltammetry on a bulk gold electrode and a thin‐layer spectroelectrochemical cell. The electrochemical oxidation of NSP's on the gold electrode was quasi‐reversible and proceeded in a diffusion‐controlled regime. The formal redox potential of NSP's covered the range from 0.39 to 0.45 V vs. SCE. The electrochemical oxidation of NSP's in the thin‐layer spectroelectrochemical cell produced radical cations that showed absorbance at 385, 410 and 530 nm. Electrochemical conversion fitted the general voltammetric current‐potential equation of a reversible wave, whereas electrolysis at constant potential showed a typical Cottrell behavior. Combining of NSP's with a biologically‐relevant theophylline molecule did not change electrochemical and spectral properties of the phenoxazine core. Theophylline enlarged with NSP's demonstrated electrochemical and biocatalytic behavior similar to that of NSP's. The investigated NSP's possess electrochemical and spectral properties that are useful as biomolecular labels for electroanalysis.
Screen Printed Carbon Electrode Modified with Poly(L‐Lactide) Stabilized Gold Nanoparticles for Sensitive As(III) Detection
Authors: Song Yue‐Shian , Muthuraman Govindan , Chen Yi‐Zhen , Lin Chu‐Chieh , Zen Jyh‐Myng
Published: September 2006

Poly(L‐lactide) stabilized gold nanoparticles (designated as PLA–AuNP) with an average particle size of ca. 10 nm were used to modify a disposable screen‐printed carbon electrode (SPE) for the detection of As(III) by differential pulse anodic stripping voltammetry. Gold modification was evaluated by cyclic voltammetry, whereas scanning electron microscopy and transmission electron microscopy revealed the size and distribution of gold nanoparticles. The PLA–AuNP/SPE was applied effectively to detect toxic As(III) in HCl medium. Under the optimal experimental conditions, a linear calibration curve up to 4 ppm with a detection limit (S/N=3) of 0.09 ppb was obtained. The sensitivity was good enough to detect As(III) at levels lower than the current EPA standard (10 ppb). Most importantly, the PLA–AuNP/SPE can be tolerable from the interference of Cu, Cd, Fe, Zn, Mn, and Ni and hence provides a direct and selective detection method for As(III) in natural waters. Practical utility of the PLA–AuNP/SPE was demonstrated to detect As(III) in “Blackfoot” disease endemic village groundwater from southwestern coast area of Taiwan (Pei‐Men).
Genotyping fetal paternally inherited SNPs by MALDI‐TOF MS using cell‐free fetal DNA in maternal plasma: Influence of size fractionation
Authors: Li Ying , Wenzel Friedel , Holzgreve Wolfgang , Hahn Sinuhe
Published: September 2006

The determination of fetal point mutations from fetal cell‐free DNA (cf‐DNA) in maternal plasma is technically challenging due to the preponderance of maternal sequences. It has recently been shown that fetal cf‐DNA sequences are smaller than maternal ones and that the selection of small cf‐DNA fragments by size fractionation by agarose gel electrophoresis leads to the enrichment of fetal cf‐DNA sequences, thereby permitting the detection of otherwise masked fetal point mutations. In a separate development, the use of MALDI‐TOF MS has also been shown to facilitate the detection of fetal point mutations from cf‐DNA in maternal plasma. In this study, a combination of these approaches was examined. cf‐DNA was extracted from 18 maternal plasma samples, 10 taken at term and 8 obtained early in the second trimester. A total of 41 SNP loci were examined in size‐fractionated and total cf‐DNA using either a conventional homogeneous MassEXTEND® (hME) assay or a nucleotide‐specific single allele base extension reaction (SABER) assay. The analysis of total cf‐DNA indicated that size fractionation considerably enhanced the sensitivity of the standard hME assay, especially for samples taken early in pregnancy. Size fractionation also rendered the signals obtained by the SABER assay more precise.
Capillary separations enabling tissue proteomics‐based biomarker discovery
Authors: Guo Tong , Lee Cheng S. , Wang Weijie , DeVoe Don L. , Balgley Brian M.
Published: September 2006

Development of the capability to enable large‐scale proteome studies, analogous to comprehensive gene expression analysis, will clearly have far‐reaching impacts on protein biomarker investigations of human diseases such as cancer through interrogation of the archived fresh frozen and formalin‐fixed and paraffin‐embedded tissue collections. This review therefore focuses on the most recent advances in microdissection techniques and proteome platforms for procuring homogeneous subpopulations of tumor cells or structures and performing comprehensive analysis of protein profiles within tissue specimens, respectively. Developments in capillary separations capable of providing extremely high resolving power and selective analyte enrichment are particularly highlighted for their roles within the broader context of a state‐of‐the‐art integrated tissue proteome effort. The capabilities of CIEF‐based multidimensional separations for performing proteome analysis from minute samples create new opportunities in the pursuit of biomarker discovery using enriched and selected cell populations procured from tissue specimens. These proteome technological advances combined with recently developed tissue microdissection techniques provide powerful tools for those seeking to gain a greater understanding at the global level of the cellular machinery associated with human diseases such as cancer.
Cytochrome c oxidase expression in chronic and intermittent hypoxia rat gastrocnemius muscle quantitated by CE
Authors: Ripamonti Marilena , Viganò Agnese , Moriggi Manuela , Milano Giuseppina , von Segesser Ludwig K. , Samaja Michele , Gelfi Cecilia
Published: September 2006

We investigated the effects of hypoxia and intermittent hypoxia in rat muscle by quantitating the expression of genes encoding cytochrome c oxidase (CytOx) subunits I, II and IV, and ribosomal 12S RNA. The quantitative assessment was made by CE in a polymer network, laser being used to facilitate the detection of induced fluorescence. Constant and intermittent hypoxia influence gene expression and ribosomal activity to different degrees. We found constant hypoxia to be accompanied by an increment in the mitochondrial CytOx subunit transcripts II and I and 12S ribosomal subunit, whereas the nuclear subunit (IV) remained unchanged. No changes were observed in intermittent hypoxic rats. Despite the increment in messenger expression, the decrease in enzyme activity was accompanied by a decrease in citrate synthase activity, a marker of mitochondrial function. The increment in CytOx mitochondrial subunits messengers and ribosomal 12S RNA under prolonged chronic hypoxia could be a consequence of reduced protein synthesis that leads to messenger accumulation.
Transient isotachophoresis in carrier ampholyte‐based capillary electrophoresis for protein analysis
Authors: Busnel Jean‐Marc , Descroix Stéphanie , Godfrin Dominique , Hennion Marie‐Claire , Kašička Václav , Peltre Gabriel
Published: September 2006

Transient ITP (t‐ITP) has been used in carrier ampholyte‐based CE (CABCE) to enhance the sensitivity of protein analysis. The characteristics of carrier ampholytes (CAs) narrow pH cuts‐based buffers, when used as BGEs in CE are compatible with t‐ITP requirements. Indeed, being the sole buffering species of such solutions, CAs impose a pH close to their pI. Thus, in these solutions, the CAs possess low electrophoretic mobility. As a consequence, by adding an ionic component with high electrophoretic mobility either in the studied sample or in the BGE, a t‐ITP step can be generated. This has first been demonstrated for protein test mixtures. Then, the combination of t‐ITP with CABCE has been applied to study a real sample, the bovine milk.
Hypoxia‐induced astrocytic reaction and increased vascular permeability in the rat cerebellum
Authors: Kaur C. , Sivakumar V. , Zhang Y. , Ling E. A.
Published: September 2006

Hypoxia is an important factor linked to induction of vascular leakage and formation of brain edema. In this connection, astrocytes associated closely with the blood vessels are deemed to be involved. This study investigated the response of astrocytes to hypoxia in the adult rat cerebellum, and along with this, the integrity of the blood–brain barrier (BBB) was assessed using fluorescent and electron dense tracers. In rats subjected to hypoxia, mRNA and protein expression of hypoxia inducible factor‐1α (HIF‐1α), vascular endothelial growth factor (VEGF), glial fibrillary acidic protein (GFAP), and aquaporin‐4 (AQ4) was significantly increased. VEGF and AQ4 immunoreactive cells were identified as astrocytes by double immunofluorescence labeling. Increased VEGF tissue concentration and astrocytic swelling as observed in hypoxic rats were reduced after melatonin administration. Following intraperitoneal or intravenous injection of rhodamine isothiocyanate (RhIC) or horseradish peroxidase (HRP), leakage of both tracers was observed in hypoxic rats but not in the controls indicating that functional integrity of BBB is compromised in hypoxia/reoxygenation. Enhanced gene and protein expression of VEGF may contribute to increased permeability of blood vessels. AQ4, a water transporting protein, is upregulated in astrocytes in hypoxia suggesting the cells are involved in edema formation. To this end, melatonin may be beneficial in reducing edema as it reduced VEGF concentration and, hence, vascular permeability. © 2006 Wiley‐Liss, Inc.
Dehydroepiandrosterone sulfate (DHEA‐S) and Alzheimer's dementia in older subjects
Authors: Bo Mario , Massaia Massimiliano , Zannella Patrizia , Cappa Giorgetta , Ferrario Ermanno , Rainero Innocenzo , Arvat Emanuela , Giordano Roberta , Molaschi Mario
Published: September 2006

Objectives and Methods

We investigated the association of serum dehydroepiandrosterone sulfate (DHEA‐S) levels with dementia of Alzheimer's type (DAT) and impairment in selected cognitive domains (memory, language, attention and working memory) in 158 patients (75.5 ± 6.7 years, 46 men) with first‐diagnosed probable DAT and in 158 age‐ and sex‐matched controls. As secondary goal, we evaluated whether DHEA‐S baseline levels were associated with cumulative 6‐year mortality.

Results

A negative correlation between DHEA‐S levels and age was observed (R = −0.25, p < 0.001). Age‐stratified analysis did not show significant differences of DHEA‐S levels between DAT patients and controls. No significant association was found between DHEA‐S levels and impairment in selected cognitive domains. Cox regression analysis showed that baseline DHEA‐S levels were not associated with cumulative 6‐year mortality.

Conclusions

In a sample of newly‐diagnosed DAT patients, we did not find significant association between presence of DAT or impairment in cognitive domains and DHEA‐S levels; baseline DHEA‐S levels are not associated with cumulative mortality in patients and controls. Copyright © 2006 John Wiley & Sons, Ltd.
Costs of community‐based public mental health services for older adults: variations related to age and diagnosis
Authors: Gilmer Todd , Ojeda Victoria D. , Folsom David , Fuentes Dahlia , Criado Viviana , Garcia Piedad , Jeste Dilip V.
Published: September 2006

Background

Several studies have examined service use among older adults although, to our knowledge, none has examined costs from a systems perspective. This study examined use and costs of mental health services among older adults in San Diego County in order to determine how expenditures and modes of service varied by age cohort and psychiatric diagnosis.

Methods

Utilization data from San Diego County Adult and Older Adult Mental Health Services (AOAMHS) were used to identify older adults (age ≥ 60) receiving services in the community during fiscal year 2003–2004. Cost data were derived from detailed examination of cost reports, and Medicaid fee schedules. Trends in demographic and clinical characteristics by six age cohorts were described. Multivariate models were used to estimate the relationships between costs, age, and clinical diagnosis while controlling for other demographic and clinical characteristics. Components of costs were also examined.

Results

Total expenditures declined from age cohorts 60–64 through ages 85 and over. Expenditures were similar, and greatest, for clients with schizophrenia and bipolar disorder, while outlays were lower for those with major depression, other psychotic disorder, other depression, anxiety, substance use disorder, and cognitive disorders. Clients diagnosed with cognitive disorder had high use of emergency services and little connection to outpatient services.

Conclusions

Expenditures were related to age and clinical diagnosis. Future efforts should investigate older adults' pathways to care, and should determine whether older adults presenting in emergency services would benefit from a specialized case management program providing linkages to community based resources. Copyright © 2006 John Wiley & Sons, Ltd.
Do symptoms of memory impairment correspond to cognitive impairment: a cross sectional study of a clinical cohort
Authors: Archer H. A. , MacFarlane F. , Price S. , Moore E. K. , Pepple T. , Cutler D. , Frost C. , Fox N. C. , Rossor M. N.
Published: September 2006

Background

Symptoms of memory loss are a common complaint within the general population and a frequent reason for seeking medical advice. However, the clinical relevance of these symptoms to future development of neurodegenerative disease is uncertain. The aim of this study is to characterise a cohort of individuals with symptoms of memory loss and varying memory impairment, who will be followed longitudinally with serial neuropsychology and neuroimaging to evaluate the clinical relevance of symptoms of memory loss.

Method

Fifty‐eight subjects with symptoms of memory loss were recruited from the National Hospital for Neurology and Neurosurgery. All subjects underwent clinical assessment, APOE4 genotyping, neuroimaging and neuropsychological tests.

Results

Those with mild cognitive impairment (MCI) had an increased prevalence of the APOE4 allele, impaired performance on tests of memory, measures of IQ and naming compared to controls. Baseline brain volumes were decreased and ventricular size increased. Those with symptoms of memory loss but no cognitive impairment (SNCI) performed significantly worse on tests of memory than the control group.

Conclusions

The MCI represent a group with multiple risk factors for progression to AD. The SNCI group may represent a heterogeneous group with some individuals in the early stages of AD whilst others' memory complaints are more likely linked to anxiety or personality traits. Copyright © 2006 John Wiley & Sons, Ltd.
Rates and previous disease history in old age suicide
Authors: Koponen Hannu J. , Viilo Kaisa , Hakko Helinä , Timonen Markku , Meyer‐Rochow V. Benno , Särkioja Terttu , Räsänen Pirkko
Published: September 2006

Objective

Suicide rates in persons over 65 have been reported to be higher than those of younger age groups. Since the absolute number of suicides in the elderly is expected to rise, more precise ways to identify potential risk factors for elderly suicides are needed.

Methods

On the basis of forensic examinations suicide rates and methods in elderly Finns of northern Finland were compared with those of adults aged 18–64 years. Data from earlier illnesses of the suicide victims were scrutinized for records of multiple physical disorders.

Results

Over the 15‐year period the mean annual suicide rate per population of 100 000 was significantly lower in the elderly (22.5) than adults aged 18–64 years (38.4). A decrease in suicide rates over time occurred in both groups. Suicide methods among elderly were more often violent, and they were seldom under the influence of alcohol. They also had a high prevalence of previous hospital‐treated depressive episodes and hospital‐treated physical illnesses. A lifetime history of hospital‐treated depression was more common among elderly victims who had received hospital treatment for genitourinary diseases, injuries or poisonings after their 50th birthday.

Conclusions

Our results from elderly suicide victims suggest an association between multiple physical illnesses and a history of depression. Especially, genitourinary diseases as well as hospital treatment due to injuries or poisonings were shown to associate with depression. Elderly Northern Finns showed lower suicide rates, and they decreased during the study period suggesting that active preventive measures against suicide are also feasible in the elderly. Copyright © 2006 John Wiley & Sons, Ltd.
Do the ABCS 135 short cognitive screen and its subtests discriminate between normal cognition, mild cognitive impairment and dementia?
Authors: Standish Timothy I. M. , Molloy D. William , Cunje Alwin , Lewis David L.
Published: September 2006

Background

Cognitive screening instruments are either too long for routine clinical use or not sensitive to distinguish mild cognitive impairment (MCI) from normal cognition (NC) or dementia.

Objective

To evaluate the sensitivity and specificity of the AB Cognitive Screen (ABCS) and its subtests with a view to improving its ability to differentiate between dementia, MCI and NC. The influence of age and education on sensitivity and specificity is also examined.

Design

Cross‐sectional study.

Methods

Participants with dementia and MCI were recruited from those presenting to four specialty geriatric clinics in southern Ontario. Participants with NC were recruited from the family and friends of patients. A comprehensive geriatric assessment was done including ABCS, SMMSE and 15 point Geriatric Depression Scale. Analysis of variance and receiver operating characteristic (ROC) curves compared test scores. SMMSE scores were also analysed for comparison purposes.

Results

Three hundred and two participants had dementia, 166 had MCI and 174 had NC. ABCS total scores were significantly different between NC and MCI (mean difference 7.1, 1.8–12.5 CI, p = 0.000) while SMMSE scores were not (mean difference 0.5, −0.7–1.7, p < 0.628). Of individual ABCS subtests, verbal fluency and delayed recall were most sensitive to differences between NC and MCI. ROC curve analysis, which presents sensitivity and specificity, showed verbal fluency was better than delayed recall in distinguishing between NC and MCI, among participants 75 years of age or older.

Conclusion

The AB Cognitive Screen (ABCS) can be administered in 3–5 min. The SMMSE and ABCS total and subtests significantly distinguished between dementia and MCI or NC. Verbal fluency and delayed recall were best at distinguishing between MCI and NC. The analysis illustrates how each subtest contributes to the sensitivity of the ABCS and suggests ways that sensitivity might be improved. Copyright © 2006 John Wiley & Sons, Ltd.
GP concordance with advice for treatment following a multidisciplinary psychogeriatric assessment
Authors: Wolfs Claire A. G. , Verhey Frans R. J. , Kessels Alfons , Winkens Ron A. G. , Severens Johan L. , Dirksen Carmen D.
Published: September 2006

Objective

To evaluate the concordance of General Practitioners (GPs) with advice for treatment after a multidisciplinary psychogeriatric assessment by the Diagnostic Observation Centre for PsychoGeriatric patients (DOC‐PG).

Method

Concordance checklists, listing the recommendations from the multidisciplinary team, were sent to the GPs in order to establish GP concordance. Regression models were used to study the associations between various patient and GP characteristics and level of concordance. Furthermore, results of a questionnaire (to identify the level of satisfaction regarding the services provided by the DOC‐PG) were compared with the level of GP concordance.

Results

Based on 530 recommendations, the overall GP concordance rate amounted to 71%. The most common types of advice pertained to medication, GP follow‐up/advice and referral. GP concordance with advice regarding admissions was the highest, followed by advice concerning the arrangement of daycare, home care and the adaptation of medication. GP concordance was lowest for referral recommendations to other specialties and recommendations regarding psychoeducation. Concordance was higher for patients who lived alone, for patients with fewer cognitive problems, when the number of recommendations did not exceed six and in group practices. Concordance was dependent on the type of advice. Satisfaction with DOC‐PG did not correlate with the level of concordance.

Conclusions

In general, GPs showed a high level of concordance with advice from the DOC‐PG. Enhancement of GP concordance can be achieved by limiting the number of recommendations, giving detailed explanations about the purpose of recommendations and educating GPs by doing. Copyright © 2006 John Wiley & Sons, Ltd.
Neural correlates of semantic and morphological processing of Hebrew nouns and verbs
Authors: Palti Dafna , Ben Shachar Michal , Hendler Talma , Hadar Uri
Published: September 2006

Neuropsychological evidence regarding grammatical category suggests that deficits affecting verbs tend to localize differently from those affecting nouns, but previous functional imaging studies on healthy subjects fail to show consistent results that correspond to the clinical dissociation. In the current imaging study, we addressed this issue by manipulating not only the grammatical category but also the processing mode, using auditory presentation of Hebrew words. Subjects were presented with verbs and nouns and were instructed to make either a semantic decision (“Does the word belong to a given semantic category?”) or a morphological decision (“Is the word inflected in plural?”). The results showed different patterns of activation across distinct regions of interest. With respect to grammatical category effects, we found increased activation for verbs in the posterior portion of the left superior temporal sulcus, left dorsal premotor area, and posterior inferior frontal gyrus. In each of these regions, the effect was sensitive to task. None of the ROIs showed noun advantage. With respect to task effects, we found a semantic advantage in left anterior inferior frontal gyrus, as well as in left posterior middle temporal gyrus. The results suggest that cerebral verb‐noun dissociation is a result of localized and subtle processes that take place in a set of left frontal and temporal regions, and that the cognitive and neural processes involved in analyzing grammatical category depend on the lexical characteristics of the stimuli, as well as on task requirements. The discrepancy between functional imaging and patient data is also discussed. Hum. Brain Mapp, 2007. © 2006 Wiley‐Liss, Inc.
Predicting costs over time using Bayesian Markov chain Monte Carlo methods: an application to early inflammatory polyarthritis
Authors: Cooper Nicola J. , Lambert Paul C. , Abrams Keith R. , Sutton Alexander J.
Published: September 2006

This article focuses on the modelling and prediction of costs due to disease accrued over time, to inform the planning of future services and budgets. It is well documented that the modelling of cost data is often problematic due to the distribution of such data; for example, strongly right skewed with a significant percentage of zero‐cost observations. An additional problem associated with modelling costs over time is that cost observations measured on the same individual at different time points will usually be correlated. In this study we compare the performance of four different multilevel/hierarchical models (which allow for both the within‐subject and between‐subject variability) for analysing healthcare costs in a cohort of individuals with early inflammatory polyarthritis (IP) who were followed‐up annually over a 5‐year time period from 1990/1991. The hierarchical models fitted included linear regression models and two‐part models with log‐transformed costs, and two‐part model with gamma regression and a log link. The cohort was split into a learning sample, to fit the different models, and a test sample to assess the predictive ability of these models. To obtain predicted costs on the original cost scale (rather than the log‐cost scale) two different retransformation factors were applied. All analyses were carried out using Bayesian Markov chain Monte Carlo (MCMC) simulation methods. Copyright © 2006 John Wiley & Sons, Ltd.
Factors controlling carbon isotope ratios of dissolved inorganic carbon in two major tributaries of the Han River, Korea
Authors: Lee Kwang‐Sik , Ryu Jong‐Sik , Ahn Kyu‐Hong , Chang Ho‐Wan , Lee Dongho
Published: September 2006

Understanding the carbon cycle of the Han River system in Korea is of prime interest in managing and preserving this valuable water resource for more than 20 million residents in the area. As a part of a comprehensive carbon cycling study for the Han River system, this report focuses on the carbon isotope compositions of dissolved inorganic carbon (DIC) in its two major tributaries, the North and the South Han Rivers. The major difference in carbonate chemistry of the tributaries originates primarily from the lithology of the catchment areas. The South Han River, draining a carbonate‐dominant terrain, has much higher alkalinities and DIC concentrations, whereas the lower concentrations in the North Han River indicate little influence of carbonate weathering. Likewise, δ13CDIC values in the South Han River indicate that the DIC input from the carbonate rocks is important in controlling carbon isotope ratios of DIC. For the North Han River, the oxidation of organic material influences the amount of riverine DIC and δ13CDIC values to a greater extent. Overall, remarkable seasonal and spatial variations of river chemistry and carbon isotope compositions of DIC reflect the variability in geo‐hydrologic characteristics, in the water regime, and in metabolic activities in the river water and/or the drainage areas. Copyright © 2006 John Wiley & Sons, Ltd.
Effects of different immersion media in multiphoton imaging of the epithelium and dermis of human skin
Authors: Hsiao Chih‐Yuan , Sun Yen , Chen Wei‐Liang , Tung Chih‐Kuan , Lo Wen , Su Jiunn‐Wen , Lin Sung‐Jan , Jee Shiou‐Hwa , Jan Gwo‐Jen , Dong Chen‐Yuan
Published: September 2006

In this work, we compared the performance of objectives with similar numerical aperture of 0.75 but different immersion media of air, water, glycerin, and oil in the imaging of human skin epithelium and dermis. In general, we found that the oil immersion objective recorded the strongest intensity at the same mechanical depth. We also characterized the focal shifts and found that with decreasing refractive index, the focal shift becomes increasingly more negative (for both the epithelium and dermis). In imaging the dermis, we estimated the image resolution at the depths of 18.8 and 30.2 μm, and found that the image resolution were comparable at these depths under the four types of immersion conditions. Our results demonstrate that by changing the immersion media, the main microscopic imaging effects are the recorded axial intensities and the focal shifts. The effects on the image resolution are negligible. Microsc. Res. Tech., 2006. © 2006 Wiley‐Liss, Inc.
Manipulation, dissection, and lithography using modified tapping mode atomic force microscope
Authors: Liu Zhiguo , Li Zhuang , Wei Gang , Song Yonghai , Wang Li , Sun Lanlan
Published: September 2006

A modified tapping mode of the atomic force microscope (AFM) was introduced for manipulation, dissection, and lithography. By sufficiently decreasing the amplitude of AFM tip in the normal tapping mode and adjusting the setpoint, the tip‐sample interaction can be efficiently controlled. This modified tapping mode has some characteristics of the AFM contact mode and can be used to manipulate nanoparticles, dissect biomolecules, and make lithographs on various surfaces. This method did not need any additional equipment and it can be applied to any AFM system. Microsc. Res. Tech., 2006. © 2006 Wiley‐Liss, Inc.
Preionization of XeF excimer laser by 248 nm laser beam
Authors: Maulhardt G , Schmidt K , Bartuch U , Viöl W
Published: September 2006

A new type of preionization setup for a XeF excimer
laser was investigated. The laser gas was ionized using a 248 nm
laser beam.

The preionization laser beam follows the optical axis of the XeF
laser resonator thereby ionizing the laser gas.

The timing of the ionizing beam with respect to the main discharge
has a great influence on laser output energy and stability. To
achieve optimum performance the preionization laser pulse should
occur about 90 ns prior to the ignition of the main discharge of
the XeF laser. The optimal energy density of the pre-ionizing beam
was found to be around 10 mJ/cm2.

By direct comparison to a standard preionization setup using a
corona discharge along the main discharge region, the pulse energy
of the XeF laser could be increased. However, the stability could
not be improved.
Time‐sharing evolution and sensitivity enhancements in 2D HSQC‐TOCSY and HSQMBC experiments
Authors: Nolis Pau , Pérez Miriam , Parella Teodor
Published: September 2006

Modifications of time‐shared (TS) HSQC‐like experiments originally developed by Griesinger and co‐workers (Sattler M, Maurer M, Schleucher J, Griesinger C. J. Biomol. NMR 1995; 5: 97) are proposed to extract different types of information from a single NMR pulse scheme. It is shown that simultaneous acquisition of 1H,13C and 1H,15N HSQC‐TOCSY and HSQMBC experiments can afford experimental sensitivity enhancements of 20–40% with respect to the separate acquisition of individual 13C or 15N data. In addition, the incorporation of a number of independent editing elements can be easily used for different purposes, for instance, to assign unambiguously 1H, 13C, and 15N chemical shifts, to differentiate directly from relayed cross‐peaks, or to measure simultaneously long‐range proton–carbon and proton–nitrogen coupling constants. The suggested methodologies can be applied to many different classes of nitrogen‐containing compounds and illustrative examples are provided for the peptide cyclosporine as a demonstration of the performance of such experiments. Copyright © 2006 John Wiley & Sons, Ltd.
High‐grade mucoepidermoid carcinoma of the accessory parotid gland with distant metastases identified by 18F‐FDG PET‐CT
Authors: Gomes Marcelo , Pepe Giovanna , Bomanji Jamshed , Al‐Salihi Omar , Du Yong , Gacinovic Svetislav , Ell Peter
Published: September 2006

We report a rare case of a metastatic mucoepidermoid carcinoma (MEC) arising from the accessory parotid gland in a 14‐year‐old male. In the pre‐surgical assessment, the MR and CT showed no other abnormalities apart from the primary lesion. The lesion was excised and confirmed as a high‐grade MEC. Four months later, he presented with a recurrence in his right temple. A 18F‐FDG PET‐CT showed distal metastases in cervical nodes and lungs. In view of the findings and poor prognosis of the patient, surgical intervention and radiotherapy were not given and palliative measures offered. This case shows the potential of molecular imaging with 18F‐FDG PET‐CT in these patients. Pediatr Blood Cancer 2008;50:395–397. © 2006 Wiley‐Liss, Inc.
Feasibility of ovarian tissue cryopreservation for prepubertal females with cancer
Authors: Poirot Catherine J. , Martelli Hélène , Genestie Catherine , Golmard Jean‐Louis , Valteau‐Couanet Dominique , Helardot Pierre , Pacquement Hélène , Sauvat Frédérique , Tabone Marie‐Dominique , Philippe‐Chomette Pascale , Esperou Hélène , Baruchel André , Brugieres Laurence
Published: September 2006

Background

Loss of fertility is one of the long‐term adverse effects of high‐dose chemotherapy or total body irradiation for cancer, even in children. Ovarian tissue cryopreservation (OTC) may make it possible for survivors of childhood cancer to have children. We evaluated the feasibility of this technique for prepubertal girls.

Methods

Between September 2000 and February 2005, 49 prepubertal girls were referred to the Reproductive Biology Unit for OTC before sterilizing treatment.

Results

One ovary each was collected from 47 patients, by laparoscopy in 24 patients and laporotomy in the others. In 16 cases, the ovary was harvested during laparotomy to resect a residual abdominal tumor. No complications occurred after operations. Ovarian tissue was frozen by a slow‐cooling protocol, using DMSO and sucrose as cryoprotectants. An mean of 17.6 ± 6.5 ovarian tissue fragments was cryopreserved per patient. Follicle concentration was evaluated histologically for 46 patients and a strong correlation was found between age and follicular density. None of the cases had visible ovarian tumor components. Ovarian cryopreservation was not carried out for two patients.

Conclusion

The cryopreservation of ovarian tissue could be systematically offered even to prepubertal girls at risk of sterility due to gonadotoxic treatment. Pediatr Blood Cancer 2007;49:74–78. © 2006 Wiley‐Liss, Inc.
Structural basis for the observed differential magnetic anisotropic tensorial values in calcium binding proteins
Authors: Mustafi Sourajit M. , Mukherjee Sulakshana , Chary Kandala V. R. , Cavallaro Gabriele
Published: September 2006

Lanthanide ions (Ln3+), which have ionic radii similar to those of Ca2+, can displace the latter in a calcium binding protein, without affecting its tertiary structure. The paramagnetic Ln3+ possesses large anisotropic magnetic susceptibilities and produce pseudocontact shifts (PCSs), which have r−3 dependence. The PCS can be seen for spins as far as 45 Å from the paramagnetic ion. They aid in structure refinement of proteins by providing long‐range distance constraints. Besides, they can be used to determine the interdomain orientation in multidomain proteins. This is particularly important in the context of a calcium binding protein from Entamoeba histolytica (EhCaBP), which consists of two globular domains connected by a flexible linker region containing 8 residues. As a first step to obtain the interdomain orientation in EhCaBP, a suite of 2D and 3D heteronuclear experiments were recorded on EhCaBP by displacing calcium with Ce3+, Ho3+, Er3+, Tm3+, Dy3+, and Yb3+ ions in separate experiments, and the PCS of 1HN and 15N spins were measured. Such data have been used in the refinement of the individual domain structures of the protein in parallel with the calculation of the respective magnetic anisotropy tensorial values, which differ substantially (2.1–2.8 times) from what is found in other Ca2+ binding loops. This study provides a structural basis for such variations in the magnetic anisotropy tensorial values. Proteins 2006. © 2006 Wiley‐Liss, Inc.
Local stray fields and magnetization reversal process of FePrB sintered magnets
Authors: Sazonov S. N.
Published: September 2006

Data have been analysed concerning the temperature dependence of the coercivityHcof Fe–Pr–B sintered magnets, which have been published in science articles over the years. Extracting the reliable experimental data, it is shown that the values of the local self‐demagnetization coefficient, having been presented in most of those articles, are exaggerated by a factor of almost 2. It is demonstrated that the simple one‐dimensional model allows one to explain the hysteresis properties of Fe–Pr–B sintered textured magnets after the revision of this value. The dependence ofHcon chemical composition is calculated. The role of intergrain exchange coupling is discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Improvement in breakdown voltage characteristics of SiC Schottky barrier diode by incorporating a guard ring‐assisted field limiting ring and an internal ring
Authors: Kim Seong‐Jin , Kim Shin , Yu Soon‐Jae , Kim Song‐Gang
Published: September 2006

We investigate the width, spacing, and number dependencies of an Al+‐implanted field limiting ring (FLR) and the influence of an Al+‐implanted internal ring on the breakdown voltage characteristics of a silicon carbide (SiC) Schottky barrier diode (SBD). SiC‐SBDs having an Al+‐implanted guard ring‐assisted FLR surrounding a Schottky contact edge and an internal ring inside a Schottky contact were fabricated via ion implantation, annealing, photolithography, and metal lift‐off techniques. The breakdown voltage characteristics of the SiC‐SBD are enhanced by incorporation of the guard ring‐assisted FLR at the Schottky contact edge and the internal ring at Schottky contact region. The breakdown voltage characteristics of the guard ring‐assisted FLR SiC‐SBDs with an internal ring are significantly dependent on the width, spacing, and number of FLRs. The breakdown voltage is improved as either the FLR width and FLR number increase or the FLR spacing decreases. 1650 V maximal breakdown voltage, corresponding to 82% ideal breakdown voltage, is observed with seven FLRs having 5 µm width and 1 µm spacing. The results indicate that a greater number of FLRs, as well as increased FLR width and decreased spacing can effectively suppress electric field crowding at the periphery of the Schottky contact edge, resulting in higher breakdown voltage. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Single‐walled carbon nanotube transistors on an ultra‐thin gate dielectric
Authors: Weitz R. Thomas , Zschieschang Ute , Klauk Hagen , Burghard Marko , Kern Klaus
Published: September 2006

Back‐gated single‐walled carbon nanotube (SWCNT) transistors were fabricated using a silane‐based organic self‐assembled monolayer as a gate dielectric on top of a highly doped silicon wafer. These ultra‐thin layers ensure strong gate coupling and therefore low operation voltages. The source and drain contacts were patterned through conventional electron‐beam lithography after deposition of the organic monolayer and the nanotubes. The organic monolayer was found to be stable against an e‐beam dose of 300 μC/cm2, as reflected by the very low gate leakage current density of 10–7 A/cm2 at a gate voltage of 2 V. On this basis, single‐electron transistors (SETs) were obtained from individual metallic SWCNTs, which display Coulomb oscillations with a period five times smaller than devices with a 200 nm SiO2 gate dielectric. Moreover, field‐effect transistors made from individual semiconducting SWCNTs operate with gate‐source voltages of –2 V, show good saturation, small hysteresis (200 mV) as well as a low subthreshold swing (290 mV/dec). (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of Ar+ irradiation on the behaviour of carbon nanotube transistor
Authors: Woo Yun Sung , Osváth Z. , Vértesy G. , Biró L. P. , Roth Siegmar
Published: September 2006

The characteristics of carbon nanotube field effect transistor are investigated after the whole device is irradiated with Ar+ ions. The resistance become much higher due to the electron scattering at vacancies produced by Ar+ irradiation. In addition, the subthreshold slop, S, (dV G/d(log I D)) increases and the Schottky barrier height decreases after the irradiation, which imply the interface states generated within the band gap of the semiconducting single walled carbon nanotube. Therefore, we suggest a way that makes a transparent contact for electron transport by manipulating the vacancy formation at the interface between nanotube and metal leads. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Semiconductor‐to‐metal transition of double walled carbon nanotubes induced by inter‐shell interaction
Authors: Zólyomi V. , Rusznyák Á. , Kürti J. , Gali Á. , Simon F. , Kuzmany H. , Szabados Á. , Surján P. R.
Published: September 2006

Nuclear magnetic resonance measurements on isotope engineered double walled carbon nanotubes (DWCNT) suggest a uniformly metallic character of all nanotubes. This effect can only be explained by the interaction between the inner and outer shell. Here we study the DWCNTs by density functional theory and inter‐molecular Hückel model. We present a study of the density of states of DWCNTs which clearly shows that two layers of semiconducting single walled nanotubes can indeed form a metallic DWCNT in many cases, but not necessarily in every case. For most metallic DWCNTs, a high density of states can be expected at the Fermi level. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural study of C60 and C70 cubane
Authors: Bortel G. , Faigel G. , Kováts É. , Oszlányi G. , Pekker S.
Published: September 2006

Fullerenes and cubane (C8H8) form new high‐symmetry heteromolecular crystals and C60–cubane and C70–cubane are the first members of this family. We present the results of a detailed structural study in a wide temperature range, from 100 K to 470 K. The structure of these compounds is based on the well‐known face centered cubic (fcc) C60 lattice. In the highest symmetry case freely rotating fullerenes occupy the fcc lattice sites, and cubanes fill the octahedral voids. We found various phase transitions on lowering the temperature. As expected, the free rotation of fullerenes becomes hindered and orientational ordering appears. The orientational transition temperature is exceptionally low, which can be explained by the combination of the high symmetry environment of fullerenes, the perfect match of convex fullerene and concave cubane molecular surfaces and the significantly expanded fullerene lattice. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Single‐walled carbon nanotubes/polycarbonate composites: basic electrical and mechanical properties
Authors: Hornbostel Björn , Pötschke Petra , Kotz Jochen , Roth Siegmar
Published: September 2006

The focus of this paper is to investigate the electrical conductivity and the mechanical properties of single‐walled carbon nanotubes/polycarbonate composites. Two different direct incorporating methods were applied. In the first method PC and SWCNTs were mixed with different ratios in a small scale conical twin screw extruder. Here, additional variations in the feeding of the filler material were tested in order to improve the state of dispersion of the melt mixing method. The second one is the coagulation method, here, the filler material was suspended and the polymer material was dissolved in liquid organic substances. The mechanical properties were examined by tension tests and by measuring the Vickers hardness. It should be stressed, that the nanofiller material was provided in large batches (m > 100 g) and extensively mechanically homogenized in order to eliminate quality fluctuations and density differences in the SWCNT occurrences. The filler material was synthesized in a Krätschmer reactor (carbon arc). After homogenization, the nanomaterial was characterized. Based on this the SWCNT content was estimated to be between 30 and 40%, which is usual for arc discharge material. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Applying Novel Molecular Electronegativity‐Interaction Vector (MEIV) to QSPR Study on Collision Cross Section of Singly Protonated Peptides
Authors: Zhou Peng , Zeng Hui , Tian Fei‐Fei , Li Bo , Li Zhi‐Liang
Published: September 2006

A novel electrotopological descriptor, Molecular Electronegativity‐Interaction Vector (MEIV), has been developed in this paper to characterize molecular structures of 420 singly protonated peptides. Three different modeling methods, as Multiple Linear Regression (MLR), Partial Least Squares (PLS), and Computational Neural Network (CNN), are utilized to explore peptide structures in relation with the Collision Cross Section (CCS). The resulting correlative coefficients R of MLR, PLS, and CNN are 0.988, 0.986, and 0.993, respectively, indicating that the MEIV descriptor is in favorable relation with CCS value, the relatationship is mainly linear with some nonlinear factors‥
Non‐parametric estimation of the case fatality ratio with competing risks data: an application to Severe Acute Respiratory Syndrome (SARS)
Authors: Jewell Nicholas P. , Lei Xiudong , Ghani Azra C. , Donnelly Christl A. , Leung Gabriel M. , Ho Lai‐Ming , Cowling Benjamin J. , Hedley Anthony J.
Published: September 2006

For diseases with some level of associated mortality, the case fatality ratio measures the proportion of diseased individuals who die from the disease. In principle, it is straightforward to estimate this quantity from individual follow‐up data that provides times from onset to death or recovery. In particular, in a competing risks context, the case fatality ratio is defined by the limiting value of the sub‐distribution function, F1(t) = Pr(T ⩽t and J = 1), associated with death, as t → ∞, where T denotes the time from onset to death (J = 1) or recovery (J = 2). When censoring is present, however, estimation of F1(∞) is complicated by the possibility of little information regarding the right tail of F1, requiring use of estimators of F1(t*) or F1(t*)/(F1(t*)+F2(t*)) where t* is large, with F2(t) = Pr(T ⩽t and J = 2) being the analogous sub‐distribution function associated with recovery. With right censored data, the variability of such estimators increases as t* increases, suggesting the possibility of using estimators at lower values of t* where bias may be increased but overall mean squared error be smaller. These issues are investigated here for non‐parametric estimators of F1 and F2. The ideas are illustrated on case fatality data for individuals infected with Severe Acute Respiratory Syndrome (SARS) in Hong Kong in 2003. Copyright © 2006 John Wiley & Sons, Ltd.
An efficient test for the analysis of dichotomized variables when the reliability is known
Authors: Borm George F. , Munneke Marten , Lemmers Oscar , van Zuijlen Martien
Published: September 2006

A difference in an outcome variable between the treatment groups in a trial does not necessarily mean that there is a difference in the number of patients who experience relevant improvement on that variable. When the relevant improvement corresponds with an outcome or change in outcome that exceeds a certain threshold, the outcome variable can be dichotomized. A responder is a patient whose outcome exceeds the threshold. Comparisons can be made between the number of responders in the two treatment groups using logistic regression, or some other method to evaluate binary outcomes. An important disadvantage of this approach is the loss of power. In general, it is more efficient to test the difference between the mean values.

We developed a statistical test that compares response rates for a dichotomized variable. It requires that an estimate of the reliability of the outcome variable is available. Simulations showed that the test was valid and robust over a wide range of distributions and sample sizes. The power was greater than the power of a χ2 test, which would enable substantial reduction in the sample size. Copyright © 2006 John Wiley & Sons, Ltd.
The Empirical Correlation Between Size and Two‐Photon Absorption Cross Section of CdSe and CdTe Quantum Dots
Authors: Pu Shih‐Chieh , Yang Meng‐Ju , Hsu Cheng‐Chih , Lai Chih‐Wei , Hsieh Cheng‐Chih , Lin Sheng Hsien , Cheng Yi‐Ming , Chou Pi‐Tai
Published: September 2006

The tuning of CdSe quantum dot (QDs) sizes, and consequently their corresponding two‐photon absorption (TPA) cross section, has been systematically investigated. As the size (diameter) of the quantum dots increases, the TPA cross section is found to be empirically related via a power‐law proportionality of 3.5±0.5 and 5.6±0.7 to the diameters of CdSe and CdTe QDs, respectively. The results are tentatively rationalized via a theoretical model of two‐photon excitation properties in a system incorporating excitons and defects.