bluuebunny/crossref_metadata_2025 huggingface dataset:
Temperament, parenting, and depressive symptoms in a population sample of preadolescents
Authors: Oldehinkel Albertine J. , Veenstra René , Ormel Johan , De Winter Andrea F. , Verhulst Frank C.
Published: October 2005

Background:  Depressive symptoms can be triggered by negative social experiences and individuals’ processing of these experiences. This study focuses on the interaction between temperament, perceived parenting, and gender in relation to depressive problems in a Dutch population sample of preadolescents.

Methods:  The sample consisted of 2230 ten‐to‐twelve‐year‐olds from the North of the Netherlands. Perceived parenting (overprotection, rejection, emotional warmth) was assessed by the EMBU (a Swedish acronym for My Memories of Upbringing) for Children, temperament (fearfulness and frustration) by the parent version of the Early Adolescent Temperament Questionnaire‐Revised, and depressive problems by the Child Behavior Checklist (parent report) and the Youth Self‐Report (child report).

Results:  All parenting and temperament factors were significantly associated with depressive problems. Frustration increased the depressogenic effect of parental overprotection and lack of emotional warmth. Fearfulness increased the effect of rejection in girls, but not in boys. Furthermore, the association between frustration and depression was stronger in boys.

Conclusions:  These findings support the hypothesis that the effect of specific parenting behaviors depends on the temperament and gender of the child.
Probability of liver cancer and survival in HCV‐related or alcoholic‐decompensated cirrhosis. A study of 377 patients
Authors: Solà Ricard , Álvarez Marco Antonio , Ballesté Belén , Montoliu Silvia , Rivera Mònica , Miquel Mireia , Cirera Isabel , Morillas Rosa Maria , Coll Susanna , Planas Ramon
Published: October 2005

Abstract: Background:Although chronic alcohol intake and chronic hepatitis C may progress to cirrhosis and hepatocellular carcinoma (HCC), few data are available about survival and probability of developing HCC in decompensated cirrhosis of both aetiologies.

Methods:This study identified factors related with probability of developing HCC and survival in a cohort of 377 consecutive patients with decompensated HCV‐related cirrhosis (200 cases) or alcoholic cirrhosis (177 cases) without known HCC, hospitalized for their first hepatic decompensation, as well as to evaluate differences between both aetiologies. Patients were followed for a mean period of 39±2 months.

Results:During follow‐up, 42 patients (11.1%) developed HCC (16.5% vs 5.1%) in groups HCV and alcohol, respectively; p=0.0008), and 131 patients (34.7%) died (42% vs 26.6% in groups HCV and alcohol, respectively; p=0.002). Age and HCV‐cirrhosis were independently related to HCC development, while baseline age and Child‐Turcotte‐Pugh score were independently correlated with survival.

Conclusion:Survival in decompensated HCV‐related or alcoholic cirrhosis is influenced by age and baseline Child‐Turcotte‐Pugh score, without differences in cirrhosis aetiology. The risk of developing HCC is greater in HCV‐related cirrhosis than in alcoholic cirrhosis.
Imaging the Developing Epileptic Brain
Authors: Grant P. Ellen
Published: October 2005

Summary:  Accurate identification of cortical malformations in children with epilepsy can be crucial for successful clinical management. Although standard head‐coil magnetic resonance imaging (MRI) at 1.5 tesla (T) can be used to view the macrostructure of the brain, phased array technology at both 1.5 and 3T significantly improves signal‐to‐noise ratio (SNR). As a result, spatial resolution and contrast can be optimized to increase visual detection of subtle macrostructural changes that occur with small epileptogenic lesions. In addition, these improvements in SNR allow more accurate quantitative analysis of brain macrostructure and more accurate assessment of brain microstructure using newer sophisticated imaging techniques. For example, phased array imaging enables more accurate diffusion tensor imaging (DTI), and 3T imaging, when combined with phased array technology, enables more informative diffusion spectroscopic imaging (DSI). Recent technological improvements therefore result in improved lesion detection and enable assessment of cerebral growth trajectories and associated longitudinal changes in tissue microstructural organization that occur in association with various types of epilepsy. This article presents a brief comparison of imaging techniques currently in use, both clinically and experimentally, to diagnose, treat, and increase our understanding of the neuropathology of epilepsy in the developing brain.
Disruption of Interneuron Development
Authors: Levitt Pat
Published: October 2005

Summary:  Disruption of gamma‐aminobutyric acid (GABAergic) interneuron development during the embryonic and early postnatal periods can have profound neurological and behavioral consequences. Hepatocyte growth factor/scatter factor (HGF/SF) has been identified as an important molecular cue that may guide the movement of interneurons from their birthplace in the ganglionic eminences (GE) to their final resting place in the neocortex. In vitro studies demonstrate that decreased HGF/SF bioactivity in pallial and subpallial tissues is associated with a reduction in the number of cells migrating out of GE explants. The uPAR knockout mouse provides a unique opportunity to study the effects of interneuron disruption in vivo. uPAR−/− mice have reduced HGF/SF bioactivity in the GE during the period of interneuron development and a concomitant 50% reduction in the number of GABAergic interneurons seeding frontal and parietal regions of the cerebral cortex. Behaviorally, these mice display an increased susceptibility to seizures, heightened anxiety, and diminished social interaction. This article discusses the commonalities between the functional defects seen in uPAR−/− mice and those of humans with developmental disorders, such as epilepsy, schizophrenia, and autism. It is suggested that disruption of GABAergic interneuron development may represent a common point of convergence underlying the etiologies of many of these developmental disorders.
Losing Neurons: Selective Vulnerability and Mesial Temporal Sclerosis
Authors: Lewis Darrell V.
Published: October 2005

Summary:  Mesial temporal sclerosis (MTS) is found in about two‐thirds of patients with refractory temporal lobe epilepsy (TLE), and surgical removal of the sclerotic structures eliminates seizures in the majority of cases undergoing surgical resection. Although multiple factors have been implicated in the genesis of MTS, it is still unclear why some individuals are more likely to develop hippocampal sclerosis than others. Epileptologists have proposed that there must be at least two factors involved—an initial precipitating injury (IPI), such as a prolonged febrile seizure, CNS infection, or head trauma, and a second factor that increases vulnerability to neuronal injury. This has been termed the “two‐hit hypothesis.” Three of the many factors that could possibly heighten susceptibility to neuronal injury and MTS are discussed here. These are microdysgenesis, hippocampal dysgenesis, prior seizures, and genetic predisposition. We conclude that there is currently no compelling evidence to support a role for microdysgenesis in MTS. Hippocampal dysgenesis, on the other hand, may account for febrile seizures and possibly MTS in a small subpopulation of patients with TLE. Additional larger studies are needed to confirm these findings. Experimental evidence indicates that an epileptogenic hippocampus can result from prolonged febrile seizures in infant rats, even though these seizures do not cause MTS in the rat. It is not known if this pathophysiological sequence occurs in humans. Lastly, there appears to be a strong genetic component that predisposes some individuals to MTS, regardless of whether they experience an IPI.
Estimating the probability of a blood donation adverse event based on 1000 interviewed whole‐blood donors
Authors: Newman B.H. , Roth A.J.
Published: October 2005

BACKGROUND: Estimating the probability that a donor will have or not have an adverse event is useful for staff knowledge to give blood donors reassurance upon request.

STUDY DESIGN AND METHODS: One‐thousand donors from the general donor pool were interviewed for seven potential adverse events 3 weeks after a 525‐mL whole‐blood phlebotomy. The four most common adverse events were bruise (22.7%), sore arm (10.0%), fatigue (7.8%), and donor reaction (7.0%). A stepwise logistic regression analysis was performed based on five donor characteristics that were studied: age, weight, sex, race, and first‐time donor status. The contribution of each significant or marginally significant factor to each adverse event was quantified.

RESULTS: For donor reaction, weight (p < 0.0001) and age (p = 0.015) were significant contributors, and first‐time donor status (p = 0.054) was a marginally significant contributor. An equation was derived, and the donor reaction rate can be estimated for a group based on the donor's weight, age, and first‐time donor status. Similar analyses were performed for fatigue, sore arm, and bruise.

CONCLUSION: Based on the derived formulas and with the use of a spreadsheet, data can be entered and the probability that a donor will have (or not have) a donor reaction, fatigue, sore arm, or bruise can be estimated.
Serial blood donations for intrauterine transfusions of severe hemolytic disease of the newborn with the use of recombinant erythropoietin in a pregnant woman alloimmunized with anti‐Ku
Authors: Lydaki Evaggelia , Nikoloudi Irene , Kaminopetros Petros , Bolonaki Irene , Sifakis Stavros , Kikidi Katerina , Koumantakis Evgenios , Foundouli Kaliopi
Published: October 2005

BACKGROUND: The management of a pregnant woman with the rare Ko phenotype and anti‐Ku is a special challenge, because matched blood is extremely rare and the possibility of severe hemolytic disease of the newborn is high.

CASE REPORT: A 30‐year‐old woman with rare Ko (Knull) phenotype presented at 18 weeks of gestation with positive indirect agglutination test results. She had anti‐Ku due to previous blood transfusion, one pregnancy, and two abortions.

STUDY DESIGN AND METHODS: During this pregnancy, anti‐Ku titers ranged from 1024 to 4096. At the 26th week of gestation ultrasound showed a hydropic fetus and urgent intrauterine exchange transfusion was performed with the maternal red blood cells (RBCs). Recombinant human erythropoietin (rHu‐EPO) and intravenous (IV) iron were administered to the mother to ensure an adequate supply of matched RBCs for intrauterine transfusions and possible perinatal hemorrhage.

RESULTS: Intrauterine transfusions were repeated every 1 to 3 weeks. By 35 weeks 2 days of gestation, the mother had donated 4 units of blood, and four intrauterine transfusions had been performed. Cesarean section was then decided and a healthy male newborn was born. He was treated with phototherapy but without exchange transfusions. By the 15th day of life rHu‐EPO was administrated to the newborn because of anemia. The maternal RBCs completely disappeared from the child's blood by Day 100.

CONCLUSIONS: As shown in this case, treatment with rHu‐EPO and IV Fe has effectively increased the mother's capacity to donate RBCs for autologous use and intrauterine transfusions, with no adverse effects to the mother or the child.
Exposure of hematologic patients to parvovirus B19 as a contaminant of blood cell preparations and blood products
Authors: Plentz Annelie , Hahn Joachim , Knöll Antje , Holler Ernst , Jilg Wolfgang , Modrow Susanne
Published: October 2005

BACKGROUND:Patients with hematologic malignancies often require blood products, and parvovirus B19 is known to be transmitted by this route. Primary infection with parvovirus B19 shows a wide variety of disease manifestation. In immunocompromised patients, symptoms are severe and viral clearance is delayed or missing.

STUDY DESIGN AND METHODS:A total of 2123 blood products given to all patients of a hematologic ward over a period of 6 months were retrospectively examined for the presence of parvovirus B19 DNA by an in‐house real‐time polymerase chain reaction (PCR; TaqMan). Patients who had received B19 DNA–positive blood products were further investigated serologically and by PCR for the presence of parvovirus B19 antibodies and DNA.

RESULTS:Twenty‐one (1%) of 2123 blood products tested positive for the presence of B19 DNA (2% of pooled products, 0.7% of single‐donor products, and 17.6% of allogeneic peripheral blood progenitor cells), the median viral load was 700 genome equivalents per mL. During the study period, 114 patients were treated on the ward, and 14 (12%) of them received B19 DNA–positive blood components. None of them developed symptoms of an acute B19 infection, although one had a short low‐level viremia.

CONCLUSIONS:Although B19 DNA was detected in 1 percent of blood products given to hematologic patients, the exposure of 12 percent of patients did not result in symptomatic infections.
Effect of resin hydrophilicity on water‐vapour permeability of dental adhesive films
Authors: King Nigel M. , Hiraishi Noriko , Yiu Cynthia K. Y. , Pashley Edna L. , Loushine Robert J. , Rueggeberg Fred A. , Pashley David H. , Tay Franklin R.
Published: October 2005

This study examined the water‐vapour permeability of thin polymerized resin films fabricated from five co‐monomer blends of increasing degrees of hydrophilicity, as measured by their Hoy's solubility parameters. Neat resin films were prepared from five experimental light‐curable resins (n = 10). Each film was mounted in a Fisher permeability cup with 8 g of water placed inside the cup. The experiments were conducted in a modified twin‐outlet desiccator connected to a vacuum pump in one outlet to permit a continuous airflow to encourage water evaporation. Weight losses by water evaporation were measured at 3, 6, 9, 24, 30, and 48 h by using an analytical balance. Additional resin films were examined by using transmission electron microscopy (TEM) after immersion in ammoniacal silver nitrate. A significant correlation was observed between the cumulative water loss at 48 h and the Hoy's total cohesive energy density (δt). Transmission electron microscopy revealed silver‐filled channels along film peripheries and silver grains of decreasing dimensions toward the film centres in co‐monomer blends 3, 4, and 5 of increasing hydrophilicity. Hydrophilic dentin adhesives polymerized in thin films are prone to water loss by evaporation. This probably accounts for the water droplets seen on the surface of vital‐bonded dentin after the application of simplified dentin adhesives.
Inflammatogenic and adjuvant properties of HEMA in mice
Authors: Sandberg Elisabeth , Kahu Helena , Dahlgren Ulf I.
Published: October 2005

2‐Hydroxyethylmethacrylate (HEMA), a common constituent in dental materials, is known to cause hypersensitivity reactions. While the means by which this small molecule causes adverse responses has not been ascertained, we have previously demonstrated that it binds to protein and in mice induces the production of autoantibodies to HEMA‐conjugated self‐protein. The present study explores the inflammatory and adjuvant properties of HEMA in response to the subcutaneous injection of HEMA and a protein. Ovalbumin (OVA) was used as a ‘reporter antigen’, and mouse serum albumin (MSA), conjugated in vitro with HEMA (MSAH) to a low degree (0.5 molecules of HEMA per molecule of MSA on average), was used to mimic a possible in vivo situation. Inflammatory responses at injection sites were scored by using an ordinal scale, and immunoglobulin (Ig)G1, IgG2a, and IgE activities to OVA or MSA were assessed by enzyme‐linked immunosorbent assay (ELISA). Injections of 20 µmol HEMA induced overt inflammatory skin responses, the severity of which was influenced by the co‐administered substances. A significantly higher IgG1 and IgE response to OVA was induced by the presence of HEMA. Interestingly, injections with low conjugated MSAH only induced the production of autoantibodies if free HEMA was included at the time of immunization. These findings suggest that HEMA is an inflammatogenic substance with adjuvant properties.
Major outer membrane proteins from Porphyromonas gingivalis: strain variation, distribution, and clinical significance in periradicular lesions
Authors: Imai Masashi , Murakami Yukitaka , Nagano Keiji , Nakamura Hiroshi , Yoshimura Fuminobu
Published: October 2005

Porphyromonas gingivalis has been implicated in both marginal periodontitis and periapical infection. This study examined the major outer membrane proteins, from P. gingivalis, which related to periradicular lesions. Outer membrane protein profiles of P. gingivalis ATCC 33277 and W83 were compared by sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE) and N‐terminal amino acid analysis. Most outer membrane proteins, such as RagA, gingipains, and OmpA‐like proteins, were found in both strains in a similar distribution pattern; however, the migration positions of Lys‐gingipain and RagB were inverted in SDS–PAGE. Western blot analysis showed that RagA, RagB, and OmpA‐like proteins were found in all of the P. gingivalis strains tested. The antiserum of W83 against RagB reacted poorly to some strains, such as ATCC 33277. When strains phylogenetically related to P. gingivalis were examined, RagA and OmpA homologs were immunologically detected in several strains. However, none of the RagB homologs were detected in any strain analyzed, suggesting that RagB is unique to P. gingivalis. To examine immunoreactive antigens in P. gingivalis, sera from patients with periradicular lesions were used. More than half of the sera showed strong reactions to P. gingivalis cell components, especially RagB. Our results indicate that a major outer membrane protein, RagB, is a possible virulence factor in periradicular lesions.
Medical health care professionals' assessments of oral health needs in children with disabilities: a qualitative study
Authors: Hallberg Ulrika , Klingberg Gunilla
Published: October 2005

Good collaboration between medical and dental care is essential to provide not only good oral health care, but also more holistic care for children with disabilities. The aim was to explore and describe medical health care professionals' assessments and considerations of orofacial problems and treatment needs in children with disabilities and in their families. In‐depth interviews focusing on orofacial function were carried out with 17 medical health care employees. Interviews were transcribed verbatim and analysed in open and focused (selective) coding processes according to grounded theory. A core category was identified and namedfocusing on basic needs, showing that oral health care assessment was not on the agenda of medical health care professionals, but was instead viewed as a responsibility of parents or dentists. This study shows that oral health issues are not fully integrated in the medical care of children with disabilities. The omission of oral health issues from the medical agenda implies a risk of oral health problems in children with disabilities. To put the oral cavity and oral health on the medical agenda, dentists need to influence the undergraduate training of medical professionals and to initiate co‐operation with the medical care system.
Polymerization contraction of resin composite vs. energy and power density of light‐cure
Authors: Asmussen Erik , Peutzfeldt Anne
Published: October 2005

This study measured the polymerization contraction of a resin composite cured at three levels of energy density, each attained at six different levels of power density. The polymerization contraction of the composite was recorded by the method of the deflecting disc (n = 5) for 1 h following the start of irradiation. Power densities of 50, 100, 200, 400, 800 and 1,000 mW cm−2, as measured on a dental radiometer, were obtained by variation of distance and supply voltage of a commercial light‐curing unit. The spectral distribution at each power density was recorded using a spectrophotometer. The absorption spectrum of camphorquinone was also recorded, and the efficiency of the radiation at each power density was calculated as the integral over wavelength of the product of absorption and emission. From the slope of the contraction curves, an approximation to the initial rate of polymerization, Rp, was calculated and was taken as an alternative measure of power density. Statistical analyses showed that polymerization contraction increased significantly with increasing levels of energy density received by the resin composite, and, for each level of energy density, that the contraction decreased significantly with increasing power density.
Smoking affects the self‐healing capacity of periodontal tissues. A histological study in the rat
Authors: Benatti Bruno Braga , César‐Neto João Batista , Gonçalves Patrícia Furtado , Sallum Enílson Antônio , Nociti Francisco Humberto
Published: October 2005

This study aimed to evaluate in rats the impact of cigarette smoke inhalation (CSI) and nicotine administration (NA) on a periodontal healing model in the absence of a plaque biofilm. Wistar rats (n = 42) were assigned to three groups: Group 1, control (n = 14); Group 2, NA (3 mg kg−1) (n = 14); and Group 3, CSI (n = 14). Thirty days after CSI and NA exposure, fenestration defects were created buccally to the distal root of the first mandibular molar. The animals were killed 21 d later and their mandibles were processed for histological examination. The percentage of bone fill and the density of newly formed bone were assessed histometrically. Intergroup analysis demonstrated that compared to the control and NA groups, CSI was associated with a reduced rate of bone repair. No new cementum had been formed along the root surface in any of the three groups. It is concluded that cigarette smoke reduces the self‐healing capacity of periodontal tissues.
Evaluation of two matrix materials intended for fiber‐reinforced polymers
Authors: Segerström Susanna , Meriç Gökçe , Knarvang Torbjørn , Ruyter I. Eystein
Published: October 2005

Two matrix resins for fiber composites that remain in a fluid state during storage and handling before polymerization were evaluated. The resin mixtures, based on methyl methacrylate (MMA), were produced with two different cross‐linking agent systems: 1,4‐butanediol dimethacrylate and ethylene glycol dimethacrylate or diethylene glycol dimethacrylate. Water sorption, water solubility, water uptake and residual MMA monomer were determined. Thermomechanical analysis was used to determine linear dimensional changes as a function of temperature. Flexural strength and modulus as well as fracture work and the maximum stress intensity factor were determined. The results revealed similar values for both matrix polymers regarding water sorption, water solubility, water uptake, residual MMA monomer (0.5 wt% (± 0.03)) and coefficient of linear thermal expansion. Flexural strength for polymer B was 68.7 MPa (± 9.8) compared to 56.0 MPa (± 13.3) for polymer A when tested dry and 64 MPa (± 6.1) compared to (54 MPa (± 3.3) when water‐saturated. Fracture toughness tests showed higher maximum stress intensity factor values for polymer B (0.75 ± 0.17) MPa × m½ than for polymer A (0.55 ± 0.12) MPa × m½. The resin binders showed an appropriate consistency while remaining in a fluid state during storage and manipulation.
Habitual daily masseter activity of subjects with different vertical craniofacial morphology
Authors: Farella Mauro , Michelotti Ambra , Carbone Gioconda , Gallo Luigi Maria , Palla Sandro , Martina Roberto
Published: October 2005

Little is known about the habitual daily masticatory activity of subjects with different vertical craniofacial morphology. The purpose of the present study was to compare the daily long‐term muscle activity of short‐face subjects with that of long‐face subjects as assessed in their natural environment. Digital photographs of the facial profile were obtained from a sample of 300 subjects and the ratio between anterior total and anterior lower facial height was assessed (Vertical Facial Index: VFI). Fourteen long‐face and 16 short‐face subjects were selected from the opposite tails of the frequency distribution of VFI. Long‐term masseter activity was monitored for 8 h d−1 in the natural environment by means of portable one‐channel electromyograph recorders over three working days. Assessments included calculation of the number of activity periods (APs) per h (N/h), their mean amplitude (Amean), and their mean duration (Dur). The maximal electromyogram activity did not differ significantly between the short‐face and the long‐face subjects. There was no significant difference between the two groups investigated in N/h, in Amean and Dur. The findings suggest that habitual activity of masseter muscle in the natural environment was not influenced by the vertical craniofacial morphology as assessed in the present study.
Human mitochondrial complex I assembly is mediated by NDUFAF1
Authors: Vogel Rutger O. , Janssen Rolf J. R. J. , Ugalde Cristina , Grovenstein Melissa , Huijbens Richard J , Visch Henk‐Jan , van den Heuvel Lambert P. , Willems Peter H. , Zeviani Massimo , Smeitink Jan A. M. , Nijtmans Leo G. J.
Published: October 2005

Complex I (NADH:ubiquinone oxidoreductase) is the largest multiprotein enzyme of the oxidative phosphorylation system. Its assembly in human cells is poorly understood and no proteins assisting this process have yet been described. A good candidate is NDUFAF1, the human homologue of Neurospora crassa complex I chaperone CIA30. Here, we demonstrate that NDUFAF1 is a mitochondrial protein that is involved in the complex I assembly process. Modulating the intramitochondrial amount of NDUFAF1 by knocking down its expression using RNA interference leads to a reduced amount and activity of complex I. NDUFAF1 is associated to two complexes of 600 and 700 kDa in size of which the relative distribution is altered in two complex I deficient patients. Analysis of NDUFAF1 expression in a conditional complex I assembly system shows that the 700 kDa complex may represent a key step in the complex I assembly process. Based on these data, we propose that NDUFAF1 is an important protein for the assembly/stability of complex I.
Si‐face stereospecificity at C5 of coenzyme F420 for F420H2 oxidase from methanogenic Archaea as determined by mass spectrometry
Authors: Seedorf Henning , Kahnt Jörg , Pierik Antonio J. , Thauer Rudolf K.
Published: October 2005

Coenzyme F420 is a 5‐deazaflavin. Upon reduction, 1,5 dihydro‐coenzyme F420 is formed with a prochiral centre at C5. All the coenzyme F420‐dependent enzymes investigated to date have been shown to be Si‐face stereospecific with respect to C5 of the deazaflavin, despite most F420‐dependent enzymes being unrelated phylogenetically. In this study, we report that the recently discovered F420H2 oxidase from methanogenic Archaea is also Si‐face stereospecific. The enzyme was found to catalyse the oxidation of (5S)‐[5‐2H1]F420H2 with O2 to [5‐1H]F420 rather than to [5‐2H]F420 as determined by MALDI‐TOF MS. (5S)‐[5‐2H1]F420H2 was generated by stereospecific enzymatic reduction of F420 with (14a‐2H2)‐[14a‐2H2] methylenetetrahydromethanopterin.
Purification and characterization of glutamate N‐acetyltransferase involved in citrulline accumulation in wild watermelon
Authors: Takahara Kentaro , Akashi Kinya , Yokota Akiho
Published: October 2005

Citrulline is an efficient hydroxyl radical scavenger that can accumulate at concentrations of up to 30 mm in the leaves of wild watermelon during drought in the presence of strong light; however, the mechanism of this accumulation remains unclear. In this study, we characterized wild watermelon glutamate N‐acetyltransferase (CLGAT) that catalyses the transacetylation reaction between acetylornithine and glutamate to form acetylglutamate and ornithine, thereby functioning in the first and fifth steps in citrulline biosynthesis. CLGAT enzyme purified 7000‐fold from leaves was composed of two subunits with different N‐terminal amino acid sequences. Analysis of the corresponding cDNA revealed that these two subunits have molecular masses of 21.3 and 23.5 kDa and are derived from a single precursor polypeptide, suggesting that the CLGAT precursor is cleaved autocatalytically at the conserved ATML motif, as in other glutamate N‐acetyltransferases of microorganisms. A green fluorescence protein assay revealed that the first 26‐amino acid sequence at the N‐terminus of the precursor functions as a chloroplast transit peptide. The CLGAT exhibited thermostability up to 70 °C, suggesting an increase in enzyme activity under high leaf temperature conditions during drought/strong‐light stresses. Moreover, CLGAT was not inhibited by citrulline or arginine at physiologically relevant high concentrations. These findings suggest that CLGAT can effectively participate in the biosynthesis of citrulline in wild watermelon leaves during drought/strong‐light stress.
Conformational studies of a hyperthermostable enzyme
Authors: Koutsopoulos Sotirios , van der Oost John , Norde Willem
Published: October 2005

The structural features of the hyperthermophilic endo‐β‐1,3‐glucanase from Pyrococcus furiosus were studied using circular dichroism, steady‐state and time‐resolved fluorescence spectroscopy and anisotropy. Upon heat and chemical treatment the folded and denatured states of the protein were characterized by distinguishable spectral profiles that identified a number of conformational states. The fluorescence methods showed that the spectral differences arose from changes in the local environment around specific tryptophan residues in the native, partially folded, partially unfolded and completely unfolded state. A structural resemblance was observed between the native protein and the structurally perturbed state which resulted after heat treatment at 110 °C. The enzyme underwent disruption of the native secondary and tertiary structure only after incubation at biologically extremely high temperatures (i.e. 150 °C), whilst in the presence of 8 m of guanidine hydrochloride the protein was partially unfolded.
Reduction of the initial defect density and improvement of the reliability of Cu/low-k structures by a methylating treatment
Authors: Borthakur Swarnal , Satyanarayana Sri , Knorr Andreas , Kraatz Matthias , Ho Paul S.
Published: October 2005

The reliability of Cu/low-k structures after a methylating treatment has been studied. The lifetime increases for structures that have undergone the treatment and the effective k is also reduced. The lifetime improvement is believed to be due to the reduction of the defect density at the trench sidewalls. A simple percolation model shows that if there are existing defects at the trench interface, then percolation requires fewer additional defects. A reliability criterion of 1.5C∕cm2 shows that the methylating treatment decreases the defect density by a factor of 5. The energy density of the capacitor, just before failure, was calculated from the current values just before failure and the values are comparable with adhesion energies of known hard mask materials. The final failure occurs at the top horizontal interface with delamination and copper penetration.
Epitaxial growth of NiSi2 on (001)Si inside nanoscale contact holes prepared by atomic force microscope tip-induced local oxidation of the thin Si3N4 layer
Authors: Chen S. Y. , Chen L. J. , Tzeng S. D. , Gwo S.
Published: October 2005

Epitaxial NiSi2 has been grown on (001)Si inside 50–200 nm Si3N4 openings prepared by atomic force microscope tip-induced local oxidation. The morphology of epitaxial NiSi2 was found to be significantly influenced by the opening size. For specific annealing conditions, there exists a transitional opening size below which a pyramidal faceted structure of epitaxial NiSi2 is preferred. The opening size effect is attributed to a limited supply of Ni atoms, the increased interface∕volume ratio of silicides with decreasing size of openings, and the considerable stress level inside miniature openings.
Field-emission characteristics of boron–carbon–nitride nanofilm
Authors: Kimura Chiharu , Shima Hidekazu , Okada Kunitaka , Funakawa Shingo , Sugino Takashi
Published: October 2005

Addition of carbon atoms into hexagonal boron–nitride film was attempted to solve serious issues of cracking or peeling off of the substrate. Boron–carbon–nitride (BCN) nanofilms are synthesized on n-type Si(100) substrates by plasma-assisted chemical-vapor deposition with a horizontal quartz reactor. Field-emission characteristics are investigated for the BCN nanofilms with various carbon compositions. We found that no increase of the turn-on electric field of the electron emission occurs for the BCN film with carbon composition lower than 18%. However, in the range of carbon composition higher than 20%, the turn-on electric field increases rapidly with carbon composition.
Effect of film thickness and annealing temperature on the carbon induced interfacial charge of tetraethoxyorthosilicate based oxide films on p-type Si(100)
Authors: Torres Victor M. , Khazi-Syed Azghar
Published: October 2005

Tetraethoxyorthosilicate (TEOS) based silicon oxide films were deposited by plasma enhanced chemical vapor deposition and subsequently annealed in an oxidizing ambient at 950 and 1070 °C. Carbon atoms were found to segregate at the SiO2/Si interface inducing interfacial charges in excess of 1×1011cm−2 in the presence of hydrogen. The interfacial carbon and charge concentrations were dependent on the annealing temperature and film thickness. A mechanism based on the rapid diffusion of carbon toward the interface during the early stages of annealing followed by oxygen diffusion toward the interface and the subsequent oxidation of interfacial carbon is proposed as an explanation for the charge dependence on the film thickness and annealing temperature. Additional data are presented concerning the composition of interfacial carbon species as well as hydrogen diffusion through the TEOS based oxide layer.
Study of diffusion and quality control for CoSi2 formation by oxide-mediated cobalt silicidation with Ti capping
Authors: Chang Juin-Jie , Liu Chuan-Pu , Hsieh Tsung-Eong , Wang Ying-Lang
Published: October 2005

The mechanism for the enhancement of CoSi2 thin film formation and film quality control by oxide-mediated cobalt silicidation with a Ti-capping layer is discussed. It is found that Ti absorbs oxygen from the SiOx layer, which induces weak points in the SiOx layer and then enhances Co diffusion as well as CoSi2 formation. The control of the reactions between Ti and SiOx is significant because a low reaction rate cannot form a suitable thickness of CoSi2 film, whereas a high reaction rate tends to form the highly resistive CoSi phase. In addition, to maintain the SiOx layer still existing after annealing is also important because if no SiOx layer remains, unreacted Co would react with Si directly to form the highly resistive phase of CoSi, leading to the smooth interface between CoSi2 and Si and dense bulk CoSi2 thin film being destroyed.
As-doped polysilicon emitters with interfacial oxides and correlation to bipolar device characteristics
Authors: Tilke A. T. , Förster M. , Schupke K. , Freigofas A. , Wagner C. , Dahl C.
Published: October 2005

A detailed investigation of in situ-doped polysilicon emitters with interfacial oxide employed in implanted-base Si bipolar junction and epitaxial-base silicon/germanium (SiGe) heterojunction bipolar transistors is presented. In order to tune and control transistor parameters such as current amplification we modify the poly/monocrystalline silicon interface sandwiched between the emitter polysilicon and the base substrate or epitaxy. Various types of interface oxidation were examined and correlated to bipolar device data. We profoundly studied subnanometer silicon oxide growth by rapid thermal oxidation, low-pressure furnace oxidation, and chemical oxidation. Also a combination of thin chemically grown oxides with a thermal postoxidation was characterized. We correlate the oxide thickness to transistor parameters such as current amplification β. Also, the influence of As-enhanced oxide breakup during different emitter anneals as well as the dependence on annealing parameters on β was studied.
Pt-coated InN nanorods for selective detection of hydrogen at room temperature
Authors: Kryliouk O. , Park H. J. , Wang H. T. , Kang B. S. , Anderson T. J. , Ren F. , Pearton S. J.
Published: October 2005

Single crystal InN nanorods were successfully grown on c-Al2O3 by hydride-metalorganic vapor phase epitaxy. The measured resistance of bare InN nanorods does not change upon exposure to hydrogen ambient. The addition of sputter-deposited clusters of Pt onto the surface of the InN nanorods, however, produced a significant change in the measured room temperature resistance. The measured resistance changed systematically by 0.5%–12% as the ambient hydrogen concentration in N2 was varied between 10 and 250 ppm after 15 min exposure time. Importantly, a relatively low power consumption of ∼0.3mW was measured under these conditions. There was no response at room temperature to O2, N2O, or NH3 exposures.
Silicon interface trap characterization with elastic metal gate metrology
Authors: Kraus Philip A. , Ho Nhan , Bae Sang Ho , Olsen Christopher S.
Published: October 2005

The replacement of SiO2 by oxynitride or high-κ materials as the gate dielectric in advanced Si complementary metal–oxide–silicon (CMOS) technology requires an investigation of the interface quality between the dielectric and the Si substrate for any candidate dielectric. An accurate, precise and convenient metrology for the characterization of the interface trap density (Dit) would be useful to evaluate the hardware, processes, and integration schemes for the formation of alternative gate dielectrics. In this article, we report the extraction of Dit near mid-gap by implementing a well-known conductance method from small-signal measurements of MOS impedance for oxynitrides with a range of physical thicknesses and nitrogen content. The MOS system measured in this work is not formed from the fabrication of a device, but through the use of an elastic metal gate metrology system where measurements are made on unpatterned films. The technique allows rapid, precise, and quantitative information on the interface quality for gate dielectric materials.
Study of hydrogen-sensing characteristics of a Pt-oxide-AlGaAs metal-oxide-semiconductor high electron mobility transistor
Authors: Cheng Chin-Chuan , Tsai Yan-Ying , Lin Kun-Wei , Chen Huey-Ing , Hsu Wei-Hsi , Hong Ching-Wen , Lin Han-Lien , Liu Wen-Chau
Published: October 2005

A new hydrogen sensor based on a GaAs-based high electron mobility transistor (HEMT) with a catalytic Pt-oxide-Al0.24Ga0.76As (MOS) gate structure is fabricated and demonstrated. The threshold voltage shift, hydrogen detection sensitivity, and transient responses of the device under different hydrogen concentrations and temperature are measured and studied. Based on the transistor amplification action, even at an extremely low hydrogen concentration of 14ppm H2/air, the studied device shows significant drain current variation (about 0.12mA). Furthermore, the studied device can be operated under wider operating temperature regimes with remarkable hydrogen-sensing properties. The decreased hydrogen detection capability with increasing operating temperature demonstrates the exothermic reaction of the hydrogen adsorption and desorption processes.
Growth of TiO2 nanorods by two-step thermal evaporation
Authors: Wu Jyh-Ming , Shih Han C. , Wu Wen-Ti
Published: October 2005

The unique morphology of TiO2 nanorods grown in a two-step thermal evaporation process under a controlled atmosphere was observed. The first step attempts to form TiO2 seeds with a higher surface energy on the alumina substrate with lower surface energy; the second step is the growth of the TiO2 seeds gradually to form nanorods. Field emission scanning electron microscopy and Raman spectrometry were used to elucidate the morphology and the characteristic spectra, respectively. The nanorods were composed of nanobricks. The nanorods were 70–150nm in diameter and up to 2μm long, respectively. High-resolution transmission electron microscopy demonstrated that an individual nanorod exhibits a twin structure with a body-centered tetragonal rutile phase, and grows in the [110] direction. Its optical response shows a broad blue emission peak at ∼418nm as cathodoluminescence analysis.
Modeling of radial uniformity at a wafer interface in a 2f-CCP for SiO2 etching
Authors: Yagisawa T. , Shimada T. , Makabe T.
Published: October 2005

Two-frequency capacitively coupled plasmas (2f-CCP) are commonly used as a powerful tool for etching of metallic and dielectric materials. Functional separation between two sources, by which independent control of high-density plasma production and high-energy ion injection onto a wafer surface can be realized, will be strongly required for a precise control of the plasma etcher. When increasing the size of the wafer and aiming at high productivity, radial uniformity in the characteristics of SiO2 etching will become a more essential issue to be addressed. The predicted radial uniformity at the wafer interface and the functional separation have been examined numerically by using VicAddress [in Advances in Low Temperature RF plasmas, edited by T. Makabe (Elsevier, Amsterdam, 2002)] in a 2f-CCP etcher in CF4(5%)∕Ar at 50 mTorr. This etcher was driven at very high frequency (100 MHz) for the production of high-density plasma and at low frequency (1 MHz) for the bias source. The plasma structure and ion velocity distribution at a wafer interface, which have a direct influence on the property of etching, are mainly discussed. Close to the wafer edge, the distortion of the potential intrinsic to the etcher has a greater effect on the ion angular distribution rather than on the ion energy distribution, resulting in a reduction of the radial uniformity of etching.
Modified three terminal charge pumping technique applied to vertical transistor structures
Authors: Passmore L. J. , Sarpatwari K. , Suliman S. A. , Awadelkarim O. O. , Ridley R. , Dolny G. , Michalowicz J. , Wu C. -T.
Published: October 2005

Vertical metal-oxide-semiconductor field-effect transistors (MOSFETs) have evolved into dominant members in the power transistor family. Reliability issues continue to be a major concern, as economic requirements drive towards miniaturization, and higher power ratings for these devices. The charge pumping method offers a simple, direct and powerful way of assessing interface damage for planar structures. Absence of an independent substrate contact in the vertical power structure implies that conventional charge pumping, which requires a substrate contact as well as three additional contacts to the remaining terminals of the MOSFETs, cannot be applied directly to these devices. In this article, we propose an adaptation of the charge pumping technique that enables its application to three terminal devices, in general. The modified form of charge pumping was applied to assess effects of Fowler–Nordheim stressing on production level U-shaped trench-gated MOSFETs. A good correlation between transfer characteristic measurements and the proposed method has been observed.
Shutter transients during solid-source epitaxy
Authors: Heyn Ch. , Cunis S.
Published: October 2005

Effusion cells are commonly used in solid-source molecular beam epitaxy for evaporation of the source materials. A prominent inaccuracy during effusion cell operation is strong flux transients after shutter opening. We have studied the temperature and time dependent beam fluxes of effusion cells filled with the group III elements indium, aluminum, and gallium. A flux reduction due to the shutter transient up to 33% with time constants ranging from 25 to 100s is observed. A simple model of the shutter-transient behavior is proposed that well reproduces major features of the experiments. As a key point, we do not model the effusion cell simply as a Knudsen cell, but assume instead more realistic Langmuir evaporation. Our calculation results establish that heat loss due to thermal radiation from the source material surface is responsible for the shutter transient. Two applications are presented. First the calibration of beam fluxes under consideration of the shutter transient and second a technique for the compensation of the shutter transient by an optimized temperature control.
Chemically assisted ion beam etching of GaAs by argon and chlorine gases: Experimental and simulation investigations
Authors: Rhallabi A. , Gaillard M. , Elmonser L. , Marcos G. , Talneau Anne , Pommereau F. , Pagnod-Rossiaux Ph. , Landesman J. P. , Bouadma N.
Published: October 2005

A two-dimensional chemically assisted ion beam etching model (CAIBE) has been developed in connection with the experiment. The effects of the chlorine flow rate and the GaAs substrate temperature have been studied. For a low Cl2 flow rate (QCl2<2sccm), the simulation results show that the GaAs etching rate is mainly controlled by the physical etch process. Over this value, the ion assisted mechanism becomes preponderant. In the case of the band etch through the mask, the increase of the Cl2 flow rate and the temperature contribute to the improvement of the etching anisotropy and elimination of microtrenching. A good agreement between the simulations and the experiments concerning the etching rate and the etch profiles through the mask versus the flow rate and temperature have been obtained.
Control of sidewall slope in silicon vias using SF6∕O2 plasma etching in a conventional reactive ion etching tool
Authors: Figueroa R. F. , Spiesshoefer S. , Burkett S. L. , Schaper L.
Published: October 2005

The etching of anisotropic blind vias in silicon with diameters of 5–10μm and an aspect ratio ∼2–4 with controlled sidewall inclination is reported. The motivation for this work is the creation of a vertical, or three dimensional interconnect. Via formation by reactive ion etch (RIE) processing is the focus of this project. Arrays of vias have been etched in 125 mm diam silicon (100) wafers using a photoresist mask. A parallel plate RIE system with a SF6∕O2 gas mixture is used. The effects of O2∕(SF6+O2) gas flow ratio, electrode bias, and chamber pressure on etch rate and feature profile have been studied. Visualization of the via profiles using scanning electron microscopy is used to identify the key parameters that control the sidewall slope. This slope is important for the subsequent deposition of via lining materials before filling with Cu. Our results indicate that the O2∕(SF6+O2) ratio is a key parameter in determining the sidewall slope, however the electrode bias and chamber pressure are critical in determining the physical and chemical process balance that determine the anisotropy of the etch process.
Microelectromechanical device for lateral force calibration in the atomic force microscope: Lateral electrical nanobalance
Authors: Cumpson Peter J. , Hedley John , Clifford Charles A.
Published: October 2005

Calibration of lateral force microscopy cantilevers is essential for the measurement of nanonewton and piconewton frictional forces, which are critical to analytical applications of polymer surfaces, biological structures, and organic molecules at nanoscale lateral resolution. We have developed a compact and easy-to-use reference artifact for this calibration, the lateral electrical nanobalance (LEN), which can be made traceable to the Système International d'Unités. A noncontact method has been developed for measuring the lateral spring constant of these artefacts, by a combination of electrical measurements and Doppler velocimetry. Traceability is crucial to ensure that force measurements by an atomic force microscope are comparable to those made by optical tweezers and other methods. The LEN is a microelectromechanical system device fabricated by silicon-on-insulator micromachining, and therefore has extremely low mass and good immunity to vibration.