bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of hospital consultants' poor mental health on patient
care
Authors: Taylor Cath , Graham Jill , Potts Henry , Candy Jenny , Richards Michael , Ramirez Amanda
Published: March 2007

In a survey of 1794 UK NHS hospital consultants 1308 (73%) responded.
Psychiatric morbidity (General Health Questionnaire—12 score ⩾4) was present
in 32% of responders, who were twice as likely to report drinking hazardous
levels of alcohol, being irritable with patients and colleagues, reducing
their standards of care and intending to retire early (all
P<0.001). Male and mid-aged consultants were also
particularly at risk. Approaches that support consultants to practice
medicine safely throughout their careers are required.
Anterior cingulate grey-matter deficits and cannabis use in
first-episode schizophrenia
Authors: Szeszko Philip R. , Robinson Delbert G. , Sevy Serge , Kumra Sanjiv , Rupp Claudia I. , Betensky Julia D. , Lencz Todd , Ashtari Manzar , Kane John M. , Malhotra Anil K. , Gunduz-Bruce Handan , Napolitano Barbara , Bilder Robert M.
Published: March 2007

Background

Despite the high prevalence of cannabis use in schizophrenia, few studies
have examined the potential relationship between cannabis exposure and
brain structural abnormalities in schizophrenia.

Aims

To investigate prefrontal grey and white matter regions in patients
experiencing a first episode of schizophrenia with an additional
diagnosis of cannabis use or dependence (n=20) compared
with similar patients with no cannabis use (n=31) and
healthy volunteers (n=56).

Method

Volumes of the superior frontal gyrus, anterior cingulate gyrus and
orbital frontal lobe were outlined manually from contiguous magnetic
resonance images and automatically segmented into grey and white
matter.

Results

Patients who used cannabis had less anterior cingulate grey matter
compared with both patients who did not use cannabis and healthy
volunteers.

Conclusions

A defect in the anterior cingulate is associated with a history of
cannabis use among patients experiencing a first episode of schizophrenia
and could have a role in poor decision-making and in choosing more risky
outcomes.
The Stigma Scale: development of a standardised measure of the
stigma of mental illness
Authors: King Michael , Dinos Sokratis , Shaw Jenifer , Watson Robert , Stevens Scott , Passetti Filippo , Weich Scott , Serfaty Marc
Published: March 2007

Background

There is concern about the stigma of mental illness, but it is difficult
to measure stigma consistently.

Aims

To develop a standardised instrument to measure the stigma of mental
illness.

Method

We used qualitative data from interviews with mental health service users
to develop a pilot scale with 42 items. We recruited 193 service users in
order to standardise the scale. Of these, 93 were asked to complete the
questionnaire twice, 2 weeks apart, of whom 60 (65%) did so. Items with a
test–retest reliability kappa coefficient of 0.4 or greater were retained
and subjected to common factor analysis.

Results

The final 28-item stigma scale has a three-factor structure: the first
concerns discrimination, the second disclosure and the third potential
positive aspects of mental illness. Stigma scale scores were negatively
correlated with global self-esteem.

Conclusions

This self-report questionnaire, which can be completed in 5–10 min, may
help us understand more about the role of stigma of psychiatric illness
in research and clinical settings.
Mortality in people with schizophrenia in rural
China
Authors: Ran Mao-Sheng , Chen Eric Yu-Hai , Conwell Yeates , Chan Cecilia Lai-Wan , Yip Paul S. F. , Xiang Meng-Ze , Caine Eric D.
Published: March 2007

Background

Long-term mortality and the risk factors for premature death among
patients with schizophrenia living in rural communities are unknown.

Aims

To explore the 10-year mortality and its risk factors among patients with
schizophrenia.

Method

We used data from a 10-year prospective follow-up study (1994–2004) of
mortality among people with schizophrenia, and death registration data
for Xinjin County, Chengdu, China.

Results

The mortality rate was 2228 per 100 000 person-years during follow-up.
Both all-cause mortality and suicide rates were significantly greater in
male than in female patients. Age at illness onset (>45 years),
duration of illness (⩾10 years), age greater than 50 years, physical
illness, inability to work, male gender, and never having received
treatment were identified as independent predictors of increased
mortality.

Conclusions

Higher mortality rates in male patients may contribute to the higher
prevalence of schizophrenia in women compared with men in China. The
findings of risk factors for mortality should be taken into account when
developing interventions to improve outcomes among people with
schizophrenia.
Stigma: ignorance, prejudice or discrimination?
Authors: Thornicroft Graham , Rose Diana , Kassam Aliya , Sartorius Norman
Published: March 2007

The term stigma refers to problems of knowledge (ignorance), attitudes
(prejudice) and behaviour (discrimination). Most research in this area has
been based on attitude surveys, media representations of mental illness and
violence, has only focused upon schizophrenia, has excluded direct
participation by service users, and has included few intervention studies.
However, there is evidence that interventions to improve public knowledge
about mental illness can be effective. The main challenge in future is to
identify which interventions will produce behaviour change to reduce
discrimination against people with mental illness.
Using activity data to explore the influence of case-load size
on care patterns
Authors: Burns Tom , Yiend Jenny , Doll Helen , Fahy Tom , Fiander Matthew , Tyrer Peter
Published: March 2007

Background

A limited case-load size is considered crucial for some forms of
intensive case management and many countries have undertaken extensive
reorganisation of mental health services to achieve this. However, there
has been limited empirical work to explore this specifically.

Aims

To test whether there is a discrete threshold for changes in intensive
case management practice determined by case-load size.

Method

‘Virtual’ case-load sizes were calculated for patients from their actual
contacts over a 2-year period and were compared with the proportions of
contacts devoted to medical and non-medical care (as a proxy for a more
comprehensive service model).

Results

There were 39 025 recordings for 545 patients over 2 years, with a mean
rate of contacts per full-time case manager per month of 48 (range
35–60). There was no variation in the proportion of non-medical contacts
when case-load sizes were over 1:20 but there was a convincing linear
relationship when sizes were between 1:10 and 1:20.

Conclusions

Case-load size between 1:10 and 1:20 does affect the practice of case
management. However, there is no support for a paradigm shift in practice
at a discrete level.
Effect of barriers on the Clifton suspension bridge, England, on local patterns of suicide: implications for prevention
Authors: Bennewith Olive , Nowers Mike , Gunnell David
Published: March 2007

We assessed the effect of the installation of barriers on the Clifton suspension bridge, Bristol, England, in 1998 on local suicides by jumping. Deaths from this bridge halved from 8.2 per year (1994–1998) to 4.0 per year (1999–2003; P=0.008). Although 90% of the suicides from the bridge were by males, there was no evidence of an increase in male suicide by jumping from other sites in the Bristol area after the erection of the barriers. This study provides evidence for the effectiveness of barriers on bridges in preventing site-specific suicides and suicides by jumping overall in the surrounding area.
Assessing insight in schizophrenia: East meets
West
Authors: Saravanan Balasubramanian , Jacob K. S. , Johnson Shanthi , Prince Martin , Bhugra Dinesh , David Anthony S.
Published: March 2007

Background

Lack of insight has been observed in people with schizophrenia across
cultures but assessment of insight must take into account prevailing
illness models.

Aims

To determine whether culturally specific and Western biomedical
interpretations of insight and psychosis can be reconciled.

Method

Patients with schizophrenia (n=131) were assessed during
their first contact with psychiatric services in Vellore, South India.
Patients' explanatory models, psychopathology and insight were
investigated using a standard schedule translated into Tamil.

Results

Supernatural explanations of symptoms were frequent. Some insight
dimensions were weakly associated (inversely) with severity of symptoms
whereas preserved insight was associated with anxiety, help-seeking and
perception of change. Willingness to attribute symptoms to disease, in
others and in one's self, but not to supernatural forces was strongly
associated with insight.

Conclusions

The relationship between insight, awareness of illness and other clinical
variables is similar in South India to elsewhere. However, the assessment
of insight might have failed to capture locally accepted explanatory
frameworks. An inclusive conceptual model which emphasises help-seeking
is recommended.
The bipolar spectrum
Authors: Angst Jules
Published: March 2007

The two-dimensional bipolar spectrum described here comprises a continuum of
severity from normal to psychotic and a continuum from depression, via three
bipolar subgroups to mania. This combination of dimensional and categorical
principles for classifying mood disorders may help alleviate the problems of
underdiagnosis and undertreatment of bipolar disorders.
Adult and Pediatric Emergency Department Sexually Transmitted Disease and HIV Screening: Programmatic Overview and Outcomes
Authors: Mehta Supriya D. , Hall Jonathan , Lyss Sheryl B. , Skolnik Paul R. , Pealer Lisa N. , Kharasch Sigmund
Published: March 2007

Objectives: To measure the prevalence of gonorrhea, chlamydia, and human immunodeficiency virus (HIV) infection among emergency department (ED) patients who accept screening, and to assess treatment outcomes and risks for infection.

Methods: Research staff offered voluntary testing for gonorrhea and chlamydia (by urine transcription‐mediated amplification) and HIV (by enzyme immunoassay/Western blot of oral mucosal transudate) to ED patients. Pediatric (15–21 years) and adult (22–29 years) patients were eligible for gonorrhea and chlamydia testing; patients aged 15–54 years were eligible for HIV testing. The authors surveyed behavioral risks of patients accepting HIV testing.

Results: From November 2003 to May 2004, 497 of 791 eligible pediatric patients (63%) and 1,000 of 2,180 eligible adult patients (46%) accepted screening for gonorrhea, chlamydia, and/or HIV. There were 41 patients infected with gonorrhea, chlamydia, or both among 380 pediatric patients (10.8%) and 11 of 233 adult patients (4.7%); 14 of 52 patients (27%) were treated presumptively by ED clinicians. Through study efforts, 33 of the 38 remaining patients were treated (90% overall treatment). Eight HIV infections were diagnosed: seven of 969 adult patients (0.7%) and one of 459 pediatric patients (0.2%); five HIV‐infected patients (63%) received test results, and three (38%) attended an HIV clinic. Gonorrhea or chlamydia infection in pediatric patients was associated with multiple sex partners, same‐sex intercourse, and suspicion of sexually transmitted diseases by the ED clinician.

Conclusions: The high prevalence of gonorrhea and/or chlamydia infection among pediatric ED patients tested supports consideration of expanded screening. Targeted HIV screening with rapid tests merits exploration in the authors' ED, given the low‐moderate numbers of patients identified through screening, receiving test results, and linked to care.
Executive Summary: The Institute of Medicine Report and the Future of Academic Emergency Medicine: The Society for Academic Emergency Medicine and Association of Academic Chairs in Emergency Medicine Panel: Association of American Medical Colleges Annual Meeting, October 28, 2006
Authors: Handel Daniel A. , Sklar David P. , Hollander Judd E. , Asplin Brent R. , Hedges Jerris R. ,   For the Institute of Medicine/Association of American Medical Colleges Panelist Group
Published: March 2007

The findings in the Institute of Medicine's Future of Emergency Care reports, released in June 2006, emphasize that emergency physicians work in a fragmented system of emergency care with limited interhospital and out‐of‐hospital care coordination, too few on‐call specialists, minimal disaster readiness, strained inpatient resources, and inadequate pediatric emergency services. Areas warranting special attention at academic medical centers (AMCs), both those included within the report and others warranting further attention, were reviewed by a distinguished panel and include the following: 1) opportunities to strengthen and leverage the educational environment within the AMC emergency department; 2) research opportunities created by emergency medicine (EM) serving as an interdisciplinary bridge in the area of clinical and translational research; 3) enhancement of federal guidelines for observational and interventional emergency care research; 4) recognition of the importance of EM residency training, the role of academic departments of EM, and EM subspecialty development in critical care medicine and out‐of‐hospital and disaster medicine; 5) further assessment of the impact of a regional emergency care model on patient outcomes and exploration of the role of AMCs in the development of such a model (e.g., geriatric and pediatric centers of EM excellence); 6) the opportunity to use educational loan forgiveness to encourage rural EM practice and the development of innovative EM educational programs linked to rural hospitals; and 7) the need to address AMC emergency department crowding and its adverse effect on quality of care and patient safety. Strategic plans should be developed on a local level in conjunction with support from national EM organizations, allied health care, specialty organizations, and consumer groups to help implement the recommendations of the Institute of Medicine report. The report recommendations and other related recommendations brought forward during the panel discussions should be addressed through innovative programs and policy development at the regional and federal levels.
Meiotic sex chromosome inactivation
Authors: Turner James M. A.
Published: March 2007

X chromosome inactivation is most commonly studied in the context of female mammalian development, where it performs an essential role in dosage compensation. However, another form of X-inactivation takes place in the male,during spermatogenesis, as germ cells enter meiosis. This second form of X-inactivation, called meiotic sex chromosome inactivation (MSCI) has emerged as a novel paradigm for studying the epigenetic regulation of gene expression. New studies have revealed that MSCI is a special example of a more general mechanism called meiotic silencing of unsynapsed chromatin (MSUC), which silences chromosomes that fail to pair with their homologous partners and, in doing so, may protect against aneuploidy in subsequent generations. Furthermore, failure in MSCI is emerging as an important etiological factor in meiotic sterility.
Conditional activation ofPax6in the developing cortex of transgenic mice causes progenitor apoptosis
Authors: Berger Joachim , Berger Silke , Tuoc Tran Cong , D'Amelio Marcello , Cecconi Francesco , Gorski Jessica A. , Jones Kevin R. , Gruss Peter , Stoykova Anastassia
Published: March 2007

During development, Pax6 is expressed in a rostrolateral-high to caudomedial-low gradient in the majority of the cortical radial glial progenitors and endows them with neurogenic properties. Using a Cre/loxP-based approach, we studied the effect of conditional activation of two Pax6 isoforms, Pax6 and Pax6-5a,on the corticogenesis of transgenic mice. We found that activation of either Pax6 or Pax6-5a inhibits progenitor proliferation in the developing cortex. Upon activation of transgenic Pax6, specific progenitor pools with distinct endogenous Pax6 expression levels at different developmental stages show defects in cell cycle progression and in the acquisition of apoptotic or neuronal cell fate. The results provide new evidence for the complex role of Pax6 in mammalian corticogenesis.
H+ pump-dependent changes in membrane voltage are an early mechanism necessary and sufficient to induceXenopustail regeneration
Authors: Adams Dany S. , Masi Alessio , Levin Michael
Published: March 2007

In many systems, ion flows and long-term endogenous voltage gradients regulate patterning events, but molecular details remain mysterious. To establish a mechanistic link between biophysical events and regeneration, we investigated the role of ion transport during Xenopus tail regeneration. We show that activity of the V-ATPase H+ pump is required for regeneration but not wound healing or tail development. The V-ATPase is specifically upregulated in existing wound cells by 6 hours post-amputation. Pharmacological or molecular genetic loss of V-ATPase function and the consequent strong depolarization abrogates regeneration without inducing apoptosis. Uncut tails are normally mostly polarized, with discrete populations of depolarized cells throughout. After amputation, the normal regeneration bud is depolarized, but by 24 hours post-amputation becomes rapidly repolarized by the activity of the V-ATPase, and an island of depolarized cells appears just anterior to the regeneration bud. Tail buds in a non-regenerative `refractory' state instead remain highly depolarized relative to uncut or regenerating tails. Depolarization caused by V-ATPase loss-of-function results in a drastic reduction of cell proliferation in the bud, a profound mispatterning of neural components, and a failure to regenerate. Crucially, induction of H+ flux is sufficient to rescue axonal patterning and tail outgrowth in otherwise non-regenerative conditions. These data provide the first detailed mechanistic synthesis of bioelectrical,molecular and cell-biological events underlying the regeneration of a complex vertebrate structure that includes spinal cord, and suggest a model of the biophysical and molecular steps underlying tail regeneration. Control of H+ flows represents a very important new modality that, together with traditional biochemical approaches, may eventually allow augmentation of regeneration for therapeutic applications.
RALDH-independent generation of retinoic acid during vertebrate embryogenesis by CYP1B1
Authors: Chambers David , Wilson Leigh , Maden Malcolm , Lumsden Andrew
Published: March 2007

Several independent lines of evidence have revealed an instructive role for retinoic acid (RA) signalling in the establishment of normal pattern and cellular specification of the vertebrate embryo. Molecular analyses have previously identified the major RA-synthesising (RALDH1-3) and RA-degrading(CYP26A-C1) enzymes as well as other components involved in RA processing(e.g. CRABP). Although the majority of the early effects of RA can be attributed to the activity of RALDH2, many other effects are suggestive of the presence of an as yet unidentified RA source. Here we describe the identification, expression, biochemistry and functional analysis of CYP1B1, a member of the cytochrome p450 family of mono-oxygenases, and provide evidence that it contributes to RA synthesis during embryonic patterning. We present in vitro biochemical data demonstrating that this enzyme can generate both all-trans-retinal (t-RAL) and all-trans-retinoic acid (t-RA) from the precursor all-trans-retinol(t-ROH), but unlike the CYP26s, CYP1B1 cannot degrade t-RA. In particular, we focussed on the capacity of CYP1B1 to regulate the molecular mechanisms associated with dorsoventral patterning of the neural tube and acquisition of motor neuron progenitor domain identity. Concordant with its sites of expression and biochemistry, data are presented demonstrating that CYP1B1 is capable of eliciting responses that are consistent with the production of RA. Taken together, we propose that these data provide strong support for CYP1B1 being one of the RALDH-independent components by which embryos direct RA-mediated patterning.
Met acts on Mdm2 via mTOR to signal cell survival during development
Authors: Moumen Anice , Patané Salvatore , Porras Almudena , Dono Rosanna , Maina Flavio
Published: March 2007

Coordination of cell death and survival is crucial during embryogenesis and adulthood, and alteration of this balance can result in degeneration or cancer. Growth factor receptors such as Met can activate phosphatidyl-inositol-3′ kinase (PI3K), a major intracellular mediator of growth and survival. PI3K can then antagonize p53-triggered cell death, but the underlying mechanisms are not fully understood. We used genetic and pharmacological approaches to uncover Met-triggered signaling pathways that regulate hepatocyte survival during embryogenesis. Here, we show that PI3K acts via mTOR (Frap1) to regulate p53 activity both in vitro and in vivo. mTOR inhibits p53 by promoting the translation of Mdm2, a negative regulator of p53. We also demonstrate that the PI3K effector Akt is required for Met-triggered Mdm2 upregulation, in addition to being necessary for the nuclear translocation of Mdm2. Inhibition of either mTOR or Mdm2 is sufficient to block cell survival induced by Hgf-Met in vitro. Moreover, in vivo inhibition of mTOR downregulates Mdm2 protein levels and induces p53-dependent apoptosis. Our studies identify a novel mechanism for Met-triggered cell survival during embryogenesis, involving translational regulation of Mdm2 by mTOR. Moreover, they reinforce mTOR as a potential drug target in cancer.
Rab6 mediates membrane organization and determinant localization duringDrosophilaoogenesis
Authors: Coutelis Jean-Baptiste , Ephrussi Anne
Published: March 2007

The Drosophila melanogaster body axes are defined by the precise localization and the restriction of molecular determinants in the oocyte. Polarization of the oocyte during oogenesis is vital for this process. The directed traffic of membranes and proteins is a crucial component of polarity establishment in various cell types and organisms. Here, we investigate the role of the small GTPase Rab6 in the organization of the egg chamber and in asymmetric determinant localization during oogenesis. We show that exocytosis is affected in rab6-null egg chambers, which display a loss of nurse cell plasma membranes. Rab6 is also required for the polarization of the oocyte microtubule cytoskeleton and for the posterior localization of oskar mRNA. We show that, in vivo, Rab6 is found in a complex with Bicaudal-D, and that Rab6 and Bicaudal-D cooperate in oskar mRNA localization. Thus, during Drosophila oogenesis, Rab6-dependent membrane trafficking is doubly required; first, for the general organization and growth of the egg chamber, and second, more specifically, for the polarization of the microtubule cytoskeleton and localization of oskar mRNA. These findings highlight the central role of vesicular trafficking in the establishment of polarity and in determinant localization in Drosophila.
An mRNA sequence derived from the yeast EST3 gene stimulates programmed +1 translational frameshifting
Authors: Taliaferro Dwayne , Farabaugh Philip J.
Published: March 2007

Programmed translational frameshift sites are sequences in mRNAs that promote frequent stochastic changes in translational reading frame allowing expression of alternative forms of protein products. The EST3 gene of Saccharomyces cerevisiae, encoding a subunit of telomerase, uses a programmed +1 frameshift site in its expression. We show that the site is complex, consisting of a heptameric sequence at which the frameshift occurs and a downstream 27-nucleotide stimulator sequence that increases frameshifting eightfold. The stimulator appears to be modular, composed of at least three separable domains. It increases frameshifting only when ribosomes pause at the frameshift site because of a limiting supply of a cognate aminoacyl-tRNA and not when pausing occurs at a nonsense codon. These data suggest that the EST3 stimulator may modulate access by aminoacyl-tRNAs to the ribosomal A site by interacting with several targets in a ribosome paused during elongation.
Determination of Aspirin Responsiveness by Use of Whole Blood Platelet Aggregometry
Authors: Ivandic Boris T , Giannitsis Evangelos , Schlick Philipp , Staritz Peter , Katus Hugo A , Hohlfeld Thomas
Published: March 2007

Background: Insufficient platelet inhibition is associated with an increased cardiovascular risk in up to 30% of patients taking regular doses of aspirin. We describe an assay to study aspirin responsiveness.

Methods: We performed impedance aggregometry on diluted whole blood with 1 mg/L collagen and 0.5 mmol/L arachidonic acid (AA). We measured thromboxane B2 (TXB2) by RIA. We examined 66 healthy control individuals, 144 aspirin users with stable coronary artery disease (CAD), and 245 CAD patients treated with aspirin and clopidogrel. Nonresponsive samples were incubated with excess dl-lysinmonoacetylsalicylic acid.

Results: Assay imprecision (CV) was 9.8% and 8.2% at mean (SD) 6-min impedance of 13.7 (2.8) Ω and 13.6 (2.3) Ω for collagen and AA, respectively. Collagen induced stronger aggregation (P = 0.0199) in women [n = 28, 14.6 (2.4) Ω] than in men [n = 38, 13.1 (2.9) Ω], even after sample incubation with 0.1 mmol/L acetylsalicylic acid (ASA) or 1 μmol/L terbogrel, a combined inhibitor of thromboxane synthase and receptors. The sex association persisted in aspirin users, but not if clopidogrel was also taken. A 6-min impedance >8 Ω with collagen (mean − 2 SD of the controls) was taken as evidence of nonresponsiveness, particularly if incubation with ASA did not inhibit aggregation further (>2 Ω). Compared with AA, collagen identified more nonresponsive samples among aspirin users (15%) and CAD patients who also received clopidogrel (10%). Incubation with ASA improved inhibition of aggregation in 70% of samples and consistently reduced TXB2 formation during aggregation.

Conclusions: Impedance aggregometry may prove useful to study aspirin responsiveness, and incubation with ASA may help to identify nonresponders and classify resistance.
Erratum
Authors: Vlad A. , Stierle A. , Kasper N. , Dosch H. , Rühle M.
Published: March 2007

“In situ x-ray study of the γ- to α-Al2O3 phase transformation during atmospheric pressure oxidation of NiAl(110)” [J. Mater. Res. 21, 3047 (2006)]
Synthesis of Si2N2O nanowires in porous Si2N2O–Si3N4 substrate using Si powder
Authors: Lee Byong-Taek , Paul Rajat Kanti , Lee Kap-Ho , Kim Hai-Doo
Published: March 2007

The formation of synthesized Si2N2O nanowires using the process of Si nitridation depending on the addition of carbon was investigated. The diameter of the Si2N2O nanowires having a high aspect ratio of about 50–80 nm was found in the porous Si2N2O–Si3N4 substrate to which 6 wt% C was added. The synthesized Si2N2O nanowires had orthorhombic single-crystal structure covered with a thin (∼2 nm thick) amorphous layer and a large number of stacking faults along the (2 0 0) plane. The photoluminescence spectrum of Si2N2O nanowires showed a strong, stable green emission at 540 nm.
Study of the undercooling of Pb-free, flip-chip solder bumps and in situ observation of solidification process
Authors: Kang Sung K. , Cho M.G. , Lauro P. , Shih Da-Yuan
Published: March 2007

The undercooling of flip-chip Pb-free solder bumps was investigated by differential scanning calorimetry (DSC) to understand the effects of solder composition and volume, with and without the presence of an under bump metallurgy (UBM). A large amount of the undercooling (as large as 90 °C) was observed with Sn-rich, flip-chip size solder bumps sitting in a glass mold, while the corresponding undercooling was significantly reduced in the presence of a wettable UBM surface. In addition, the solidification of an array of individual solder bumps was monitored in situ by a video imaging technique during both heating-up and cooling-down cycles. Data obtained by the optical imaging method were used to complement the DSC thermal measurements. A random solidification of the array of bumps was demonstrated during cooling, which also spans a wide temperature range of 40–80 °C. In contrast, an almost simultaneous melting of the bumps was observed during heating.
Synthesis of AlN nanowires by nitridation of Ti3Si0.9Al0.1C2 solid solution
Authors: Zhang H.B. , Zhang J. , Zhou Y.C. , Bao Y.W. , Li M.S.
Published: March 2007

This paper describes a new method to synthesize AlN nanowires by the nitridation of Ti3Si0.9Al0.1C2 solid solution. Single-crystalline AlN nanowires with the hexagonal wurtzite structure can be easily prepared using this method. In particular, the resulting AlN nanowires display a new growth orientation of 〈1011〉 besides 〈1000〉 and 〈0001〉. This work indicates that MN+1AXN compounds are promising raw reactants to synthesize one-dimensional (1D) nanostructures of nitrides and oxides.
Effect of GeO2 additive on fluorescence intensity enhancement in bismuth-doped silica glass
Authors: Fujimoto Yasushi , Hirata Yuki , Kuwada Yoshiyuki , Sato Takahiro , Nakatsuka Masahiro
Published: March 2007

We observed the enhancement of fluorescence intensity due to the addition of GeO2 in bismuth-doped silica glass (BiSG), which has a peculiar fluorescence at 1.25 μm with a full width at half-maximum of 300 nm. Experimental results revealed that the fluorescence intensity from BiSG with 5.0 mol% GeO2 increased remarkably to be 26.3 times greater than that without GeO2 additive for the same Bi2O3 concentration (0.1 mol%). Furthermore, the enhanced sample showed almost the same intensity as BiSG without GeO2 for 1.0 mol% Bi2O3. These results demonstrate that GeO2 additive effectively promotes the generation of peculiar luminescent centers.
Aqueous solution diffusion in hydrophobic nanoporous thin-film glasses
Authors: Guyer Eric P. , Gantz Jay , Dauskardt Reinhold H.
Published: March 2007

We demonstrate that diffusion of aqueous buffered solutions into strongly hydrophobic nanoporous methyl silsesquioxane glass films can occur without the application of external pressure. The organic component of these glasses in the form of methyl groups imparts the strong hydrophobicity and perception that they are impervious to the ingress of aqueous solutions by capillary action or diffusion. The presence of small concentrations of organic buffering agents in buffered solutions appears to facilitate the diffusion. The diffusion distance followed a square root of time dependence characteristic of Fick’s Law. The diffusion coefficients varied markedly with the concentration of buffering agents, solution pH, and temperature. Similar effects were not observed for nonbuffered solutions that exhibited no detectable diffusion. Likely mechanisms responsible for the observed behavior are proposed.
Ionic doping effects on crystal structure and relaxation character in Bi0.5Na0.5TiO3 ferroelectric ceramics
Authors: Shan Dan , Qu Yuanfang , Song Jianjing
Published: March 2007

The effects of ionic doping in Bi0.5Na0.5TiO3 (BNT) ceramics were investigated. Pure and doped BNT samples containing 0 to 16 at.% Ba2+ and 0 to 1.0 at.% Ce4+ were synthesized at 1135 to 1200 °C for 2 h in ambient atmosphere. Temperature dependences of dielectric properties were analyzed. These results suggest that Ba2+ and Ce4+ replace the ions in A and B sites of perovskite structures, and the lattice structure is altered. The component differences of each crystal domain lead to variance of phase transition temperature, which enhances the relaxation character in BNT ceramics, and the dielectric properties were consequently improved.
Mechanism of electromigration-induced failure in flip-chip solder joints with a 10-μm-thick Cu under-bump metallization
Authors: Nah Jae-Woong , Chen Kai , Tu K.N. , Su Bor-Rung , Chen Chih
Published: March 2007

The electromigration-induced failure in flip-chip eutectic SnPb solder joints with a 10-μm-thick Cu under-bump metallization (UBM) was studied without the effect of current crowding in the solder region. The current crowding occurred inside the UBM instead of in the solder joint at the current density of 3.0 × 104 A/cm2 because of the spreading of current in the very thick Cu UBM. In these joints, the failure occurred through a two-stage consumption of the thick Cu UBM in the joint where electrons flowed from the chip to the substrate. In the first stage, the Cu UBM dissolved layer by layer rather uniformly across the entire Cu UBM–solder interface. In the second stage, after half of the Cu UBM was dissolved, an asymmetrical dissolution of Cu UBM took place at the corner where electrons entered from the Al interconnect to the Cu UBM. Experimental observation of dissolution steps of the 10-μm-thick Cu UBM is presented. The transition from the first stage to the second stage has been found to depend on the location of current crowding in the flip-chip joints as the UBM thickness changes during the electromigration test. The current distribution in the flip-chip solder joints as a function of UBM thickness was simulated by three-dimensional finite element analysis. The dissolution rate of Cu UBM in the second stage was faster than that in the first stage. The mechanism of electromigration-induced failure in the flip-chip solder joints with a 10-μm-thick Cu UBM is discussed.
Effect of Cu content on the mechanical reliability of Ni/Sn–3.5Ag system
Authors: Kim J.Y. , Sohn Y.C. , Yu Jin
Published: March 2007

Copper was supplied to Sn–3.5Ag by electroplating Cu/Ni double under-bump metallization (UBM), and the amount of Cu was controlled by varying the Cu UBM thickness. Supposed Cu contents in the solder were; 0.2, 0.5, and 1.0 wt%, respectively, and the solder joint microstructure was investigated after 1, 5, and 10 reflows. In the case of specimens with 0.2 and 1.0 wt% Cu, only one type of intermetallic compound (IMC) formed, either (Cu,Ni)6Sn5 or (Ni,Cu)3Sn4, while two types formed in specimen with 0.5 wt% Cu. No correlation could be found between the solder joint microstructure and the ball shear test. However, drop test results showed two opposite trends. The drop resistance of 0.2 and 1.0 wt% Cu specimens was quite good initially but degraded dramatically with multiple reflows, in contrast to that of the 0.5 wt% Cu specimen, which was very poor after one reflow but improved substantially later on. The former was ascribed to thickening of IMC during reflow, while the latter was related to (Ni,Cu)3Sn4 thickening beneath (Cu,Ni)6Sn5 and subsequent spalling of (Cu,Ni)6Sn5 from (Ni,Cu)3Sn4.
Sm-based Sm–Al–Ni ternary bulk metallic glasses
Authors: Wu J. , Wang Q. , Qiang J.B. , Chen F. , Dong C. , Wang Y.M. , Shek C.H.
Published: March 2007

The Sm-based Sm–Al–Ni glass-forming system was investigated using our e/a- and cluster-related criteria. Three bulk metallic glasses (BMGs) Sm54Al23Ni23, Sm56Al22Ni22, and Sm58Al21Ni21 were obtained by suction casting into rods with a diameter of 3 mm. All of them shared a constant e/a = 1.5 and fell along the e/a-constant composition line in the ternary composition chart. The Sm54Al23Ni23 BMG exhibiting the largest Trg was located at the intersection point of the e/a-constant line and the Sm7Ni3-Al cluster line, with thermodynamic parameters of Tg = 548 K at a heating rate of 20 K/min, Tg/Tm = 0.634, and Tg/Tl = 0.615. The Sm7Ni3 cluster was a capped trigonal prism derived from the SmNi phase.
Laser-assisted spray pyrolysis process for the growth of TiO2 and Fe2O3 nanoparticle coatings
Authors: Witanachchi Sarath , Dedigamuwa Gayan , Mukherjee Pritish
Published: March 2007

We present a laser-assisted spray pyrolysis method to fabricate nanoparticle coatings of metal oxides. In this process, 1.5-μm size droplets of a titanium- or iron-containing organometallic precursor were injected into a vacuum chamber with SF6 carrier gas. The strong absorption of a 3W CO2 laser beam focused onto the injector tip in the presence of SF6 increased the temperature of the gas and the droplets to about 300 °C. Films deposited on heated substrates with and without the CO2 laser heating were studied by atomic force microscopy. The laser heating of the droplets caused the solvent to evaporate before depositing on the substrate, leading to grain sizes that are about a factor of 3 smaller than those deposited without laser heating. By controlling the concentration of the precursor in the solvent, the average particle sizes have been tuned from 80 to 50 nm.
Local epitaxy of YBa2Cu3Ox on polycrystalline Ni measured by x-ray microdiffraction
Authors: Specht E.D. , Goyal A. , Liu W.
Published: March 2007

Polychromatic synchrotron x-ray microdiffraction is used to determine the epitaxy of YBa2Cu3Ox (YBCO) films grown on polycrystalline Y.15Zr.85O1.925/CeO2/Y2O3/Ni95W5(Ni) rolling-assisted, biaxially textured substrates (RABiTS). A novel analysis technique is introduced in which the orientation of mosaic films is measured by using a Hough transform to recognize arcs in Laue microdiffraction patterns that correspond to low-index zone axes. While the overall epitaxy is cube-on-cube, grain-by-grain analysis reveals a systematic misorientation of YBCO with respect to Ni: the YBCO [001] rotates toward the direction of the surface normal. The crystal mosaic (for rotation about the rolling direction) measured by a single diffraction pattern sampling a 0.5-μm2 surface area is 0.7° full width at half-maximum for YBCO grown on Ni grains with a low tilt; for more highly tilted grains, the YBCO patterns can no longer be measured, presumably due to the large mosaic. The YBCO mosaic over the entire area of a Ni grain is ∼2.5° and varies with grain size; the mosaic is smaller for larger grains.
Atomistic study of the melting behavior of single crystalline wurtzite gallium nitride nanowires
Authors: Wang Zhiguo , Zu Xiaotao , Gao Fei , Weber William J.
Published: March 2007

Molecular dynamic simulation was used to study the melting behavior of gallium nitride (GaN) nanowires with the Stillinger-Weber potential. Our results reveal that the melting of the nanowires starts from the surface and rapidly extends to the inner regions of nanowires as temperature increases. The melting temperatures increase to saturation values ∼3100 and ∼2900 K when the diameters of nanowires are larger than 3.14 and 4.14 nm for the nanowires with [100]- and [110]-oriented lateral facets, respectively. The saturated values are close to the melting temperature of bulk GaN. The low melting temperature of GaN nanowires with small diameter may be associated with the large surfaces of nanowires.
Effects of abrasive particle size and molecular weight of poly(acrylic acid) in ceria slurry on removal selectivity of SiO2/Si3N4films in shallow trench isolation chemical mechanical planarization
Authors: Kang Hyun-Goo , Park Hyung-Soon , Paik Ungyu , Park Jea-Gun
Published: March 2007

The effects of the molecular weight and concentration of poly(acrylic acid) (PAA) with different primary abrasive sizes in ceria slurry on the nitride film loss, removal rate, film surface roughness, and removal selectivity of SiO2-to-Si3N4films were investigated by performing chemical mechanical polishing (CMP) experiments using blanket and patterned wafers. In the case of the blanket wafers, we found that for a lower PAA molecular weight, the removal selectivity of SiO2-to-Si3N4films increased more significantly with increasing PAA concentration in slurry containing a larger primary abrasive size. For the patterned wafers, with a higher PAA molecular weight in the ceria slurry suspension, the erosion of the Si3N4film was less, but the removed amount was also smaller, and the surface roughness became worse after CMP. These results can be qualitatively explained by the layer of PAA adsorbed on the film surface, in terms of electrostatic interaction and rheological behavior.
Synthesis and characterization of montmorillonite clays with modulable porosity induced with acids and superacids
Authors: Marina Vargas Rodríguez Y. , Beltrán Hiram I. , Vázquez-Labastida Eloy , Linares-López Carlos , Salmón Manuel
Published: March 2007

The structural transformation of natural montmorillonite clay with different acids and superacids (hydrochloric, HCl; sulfuric, H2SO4; hydrofluoric, HF; perchloric, HClO4; chlorosulfonic, HSO3Cl; and trifluoromethanesulfonic, HSO3CF3 acids) is evaluated by various techniques, allowing its full characterization. The process involves the modulated digestion of the aluminum and silicon atoms from the original clay without the loss of the original mass in the material from a careful drying methodology. The x-ray diffraction technique suggests that the process is disruptive, causing different magnitudes of modification, depending on the acidic source, taking the material with natural lamellar structure as reference. By 27Al and 29Si magnetic resonance, it is also shown that all the silicon and aluminum atoms were removed from the chemical structure to be physisorbed or dispersed in the interstices of the clay lattice when HF, HSO3Cl, and H2SO4 acid treatments were carried out. However, with treatment of HClO4, the results suggest that only was achieved partial digestion and physisorption of the aluminosilicate core. Treatment with HCl led to a mild digestion that increased the laminar distance of the montmorillonite. Finally, HSO3CF3 acid achieved a total disorder of the lamellar structure of the clay. In addition, by infrared spectrometry, the disappearance of the absorption peaks assigned to Al2OH, AlMgOH, and Al-O-Si are other evidence of the complete digestion of silicon and aluminum atoms caused by the acidic medium. On the other hand, the Brunauer–Emmett–Teller (BET) surface areas of the acidified clays showed a great enlargement in comparison with the unmodified clay. The porosimetry measurements demonstrate the presence of mesopores and hysteresis as observed in the physisorption isotherms, which indeed exhibited a capillary condensation into the porous structures. The present results are the first full characterization research and structural comparison between the acidic and the not-extensively-studied superacidic modified clays of this type.
Microstructural examination in high-strain-rate superplastically deformed tetragonal ZrO2 dispersed with 30 vol% MgAl2O4 spinel
Authors: Morita Koji , Hiraga Keijiro , Kim Byung-Nam , Sakka Yoshio
Published: March 2007

The role of MgAl2O4 spinel particle dispersion for attaining high-strain-rate superplasticity (HSRS) was examined in tetragonal ZrO2. Microstructural examination shows that the dispersed spinel particles provide the following positive factors to ZrO2 simultaneously: (i) stable fine grain size by retarding grain growth due to pinning effect; and (ii) enhanced accommodation due to accelerated lattice diffusivity caused by the dissolution of aluminum and magnesium into ZrO2 from the spinel particles, and accelerated relaxation of stress concentrations exerted by grain boundary sliding through dislocation motion. These positive factors make it possible to attain HSRS in ZrO2.
Highly sinter-active nanocrystalline RE2O3 (RE = Gd, Eu, Dy) by a combustion process, and role of oxidant-to-fuel ratio in preparing their different crystallographic modifications
Authors: Bedekar V. , Chavan S.V. , Tyagi A.K.
Published: March 2007

Highly sinter-active powders of RE2O3 [rare earth (RE) = Gd, Eu, Dy] have been prepared using the corresponding metal nitrates as the oxidants, and glycine and citric acid as the fuels. Two different oxidant-to-fuel ratios, namely stoichiometric ratio and fuel-deficient ratio were used to explore the possibility of preparing different crystallographic modifications. By a careful control of oxidant-to-fuel ratio, nanocrystalline Eu2O3 and Gd2O3 could be prepared in cubic (C-type) as well as monoclinic (B-type) modifications. However, the high-temperature monoclinic modification could not be obtained for Dy2O3 due to a very high C-to-B-type phase transition temperature. The crystallite size, surface area, and sintering behavior were also studied for powders prepared using different oxidant-to-fuel ratios, and the results showed a remarkable correlation between different fuel contents and powder properties. Some of these powders resulted in pellets of nearly theoretical density. The sintered microstructure was studied by scanning electron microscopy.
A high-resolution transmission electron microscopy study of defects in γ-Al2O3 nanorods
Authors: Li W.F. , Ma X.L. , Li Y. , Zhang W.S. , Zhang Z.D.
Published: March 2007

Surface and planar defect structures of γ-Al2O3 nanorods synthesized by the arc-discharge method were studied by means of high-resolution transmission electron microscopy and image simulation. Our investigation showed that there was a high number density of twins in the nanorods. We suggested a possible configuration of {111} twins in γ-Al2O3, and this model fit our experimental result well. In some nanorods, the ordering of nanotwins gave rise to a local hexagonal-like structure. The twinned nanorods were usually enclosed by {100} and {111} facets, and their growth direction was changed from 〈110〉 into 〈111〉. The surface structures of the nanorods confirmed that the {111}-type surface should be more stable.
Appropriateness of the Darroch Estimator for Monitoring Adult Chum Salmon on the Middle Yukon River, Alaska
Authors: Underwood Tevis J. , Gordon Judith A. , Millard Michael J. , Lubinski Brian R. , Klosiewski Steve P.
Published: March 2007

From 1996 to 1999, a Darroch two-sample stratified capture–recapture experiment was conducted on adult chum salmon Oncorhynchus keta in the Yukon River, Alaska. Annual release of marked chum salmon ranged from 8,527 to 18,631 fish. At the recovery site, 15,581–45,232 fish were examined for marks annually. The percentage of tagged fish among those examined for marks ranged from 2.8% to 6.4%. Abundance estimates ranged from 189,742 (SE = 6,967) to 654,296 (SE = 21,921) fish during the four study years. Weekly estimates ranged from 6,796 to 126,268 fish. The assumption of a closed population was evaluated in light of life history and other data. One closure violation due to sample starting and ending dates was mitigated using migration times. We used statistical analysis and modeling to evaluate assumptions of (1) equal probability of capture, (2) equal probability of movement, and (3) random mixing of fish. Logistic regression suggested that the probability of recapture was not independent of length and gender in 8 of 32 weeks among years. Modeling changes in the probabilities of movement and capture indicated that differences in movement would cause little bias in population estimates relative to differences in capture. However, length- and gender-stratified and unstratified population estimates showed little difference (e.g., in 1997: length-stratified estimate = 351,138 fish, gender-stratified estimate = 333,842 fish, unstratified estimate = 333,057 fish). Three explanations were offered for these results: violations were due to changes in the probability of movement, statistical tests were overly sensitive, or the estimator was robust to the assumption violations. Probability of recapture was related to bank orientation (i.e., nonrandom mixing) only in 1999. Annual estimates during the study documented a decline in the spawning population. Weekly estimates indicated that run timing was inconsistent among years. The estimates compared favorably with other assessments of the run. We concluded that the Darroch estimator was reasonably applied to data collected via fish wheels for this population.