bluuebunny/crossref_metadata_2025 huggingface dataset:
Diagnostic dilemma of “sporadic” cases of dystrophic epidermolysis bullosa: a new dominant or mitis recessive mutation?
Authors: Hashimoto I. , Kon A. , Tamai K. , Uitto J.
Published: May 2007

Abstract: Dystrophic forms of epidermolysis bullosa (DEB), characterized by mutations in the type VII collagen gene (COL7A1), are inherited either in an autosomal dominant or autosomal recessive fashion, and sporadic, de novo cases have also been reported. Clinically, the dominant forms (DDEB) can be indistinguishable from the mild, mitis forms of recessively inherited DEB (M‐RDEB). This situation poses a dilemma in case of families with 1 mildly affected individual and clinically normal parents: Is it a new dominant or mitis recessive DEB? In this study we review 2 cases with mild DEB, the parents being clinically normal. One of the cases was shown to be a compound heterozygote for 2 silent missense mutations (R2063W/G2366S), thus being diagnosed as M‐RDEB. The second case had a single glycine substitution mutation (G2079E) in COL7A1 and had therefore DDEB. These findings have implications for the genetic counseling of these families concerning the risk of recurrence of the disease in subsequent pregnancies in the present and future generations.
Dynamic aspects of protein deimination in developing mouse epidermis
Authors: Akiyama K. , Senshu T.
Published: May 2007

Abstract: The cornified layer of mammalian epidermis contains deiminated keratins and filaggrin whose arginine residues are partly converted to citrulline residues by peptidylarginine deiminase (EC 3.5.3.15). We have attempted to study dynamic aspects of protein deimination using late embryonic to early postnatal mouse skin. The epidermis was separated from the dermis by brief immersion of skin into a weakly alkaline ammonium chloride solution. The total homogenate of the epidermis was subjected to western blotting analyses for quantitative densitometry of major keratins, deiminated proteins and immunoreactive filaggrin. We found marked increases in both deiminated keratins and deiminated filaggrin from the 18th day of gestation to 2 h after birth followed by rapid decreases to minimum levels at 6 h and subsequent gradual increases sur passing the earlier levels by 72 h after birth. Such variations were associated with consistent changes of the intensity of deiminated proteins stained immunocytochemically. These results suggest that the protein deimination might play a role in dealing with the drastic environmental change after birth. Furthermore, we found compartmentalization of both total and deiminated filaggrins into soluble and particulate fractions. The soluble compartment contained relatively more deiminated filaggrin than the particulate fraction.
Mast cell chymase and tryptase during tissue turnover: analysis on in vitro mitogenesis of fibroblasts and keratinocytes and alterations in cutaneous scars
Authors: Algermissen B. , Hermes B. , Feldmann‐Boeddeker I. , Bauer F. , Henz B. M.
Published: May 2007

Abstract: In order to shed further light on the potential role of mast cells during tissue turnover, we have investigated the number of mast cells containing only tryptase and those storing both tryptase and chymase by enzyme histochemistry in normal versus healing skin. Furthermore, we have studied the in vitro effect of these enzymes on the mitogenesis of subconfluent quiescent fibroblast and HaCaT keratinocyte cultures, using flowcytometric DNA analysis. Chymase‐containing mast cell numbers were markedly decreased in scars (P<0.001), whereas the overall number of tryptase‐containing mast cells was not decreased, although these cells were smaller and stained more faintly in scars. Chymase (5 to 300 mU/ml) induced a marked, dose‐dependent in vitro mitogenic response in 3T3 fibroblasts, whereas the effects of tryptase, at up to 60 nM, were only moderate, compared to the known fibroblast mitogens EGF, TGF‐α, α‐thrombin and trypsin at optimal concentrations. Coincubation of either protease with EGF or α‐thrombin had additive effects. In contrast to fibroblasts, keratinocytes showed only minor mitogenic responses to tryptase and chymase, also in comparison to other known mitogenic stimuli, and responses to EGF and α‐thrombin were inhibited on costimulation of cells with the proteases. These findings document for the first time a potential role of mast cell chymase in connective tissue repair, with tryptase being less active on fibroblasts, and with inhibitory effects of both mast cell proteases on keratinocytes.
Topical 9‐cis‐retinaldehyde for delivery of 9‐cis‐retinoic acid in mouse skin
Authors: Didierjean L. , Sass J. O. , Carraux P. , Grand D. , Sorg O. , Plum C. , Nau H. , Saurat J.‐H.
Published: May 2007

Abstract: The 9‐cis‐retinoic acid (9cRA) is an endogenous ligand of retinoid X nuclear receptors (RXRs). Although the epidermis contains five times more RXRs than RARs, little is known on the activity of topical 9cRA. In order to circumvent surface isomerization of topically applied 9cRA into all‐trans‐retinoic acid (atRA), we used topical 9‐cis‐retinaldehyde (9cRAL) as a precursor of 9cRA, hypothesizing that keratinocytes would metabolize 9cRAL into 9‐cis‐retinoic acid (9cRA). Retinoid content was determined by HPLC analysis of mouse tail skin that had been washed after the application of 9cRAL (0.05% for 14 days) to evaluate the metabolites produced within the epidermis. Biologic activities of 9cRAL and atRAL were analysed by assessing hyperplastic and metaplastic responses, by determining epidermal thickness and the levels of mRNAs encoding for specific keratins. atRAL and derived retinoids were found in skin treated with either atRAL or 9cRAL. The metabolite pattern obtained with 9cRAL was similar to that obtained with atRAL except the presence in 9cRAL samples of an unidentified nonpolar metabolite. However, treatment with 9cRAL yielded higher atRAL and lower retinyl ester concentrations. The biologic activities (hyperplastic and metaplastic responses) resulting from topical application of 9cRAL were lower than those induced by atRAL or atRA at similar concentrations. Taken together, these data show that topical 9cRAL does not deliver significant amounts of 9cRA and exerts less biologic activity than atRAL. Contrary to atRAL, 9cRAL does not appear therefore as a pertinent candidate for topical use in humans.
Toward a canine model of atopic dermatitis: amplification of cytokine‐gene transcripts in the skin of atopic dogs
Authors: Olivry T. , Dean G. A. , Tompkins M. B. , Dow J. L. , Moore P. F.
Published: May 2007

Abstract: The objectives of the present study were to characterize and compare the repertoire of cytokine‐genes transcribed in skin homogenates obtained from normal dogs and dogs with atopic dermatitis (AD) using a reverse‐transcriptase polymerase chain reaction and canine‐specific cytokine‐gene primers. Whereas IL‐4 and IL‐5 cytokine‐gene transcripts were detected more commonly in atopic skin biopsy homogenates, IL‐2 mRNA was amplified more often from normal control specimens. IFN‐γ mRNA was detected in 5/29 atopic specimens, 4 of them obtained from the only dog with chronic skin lesions. One‐fourth of atopic samples exhibited clear type‐2 cytokine profiles; the remainder did not demonstrate polarized repertoires. Conversely, type‐1 cytokine profiles were characterized in one‐fourth of normal control specimens. The present study establishes, for the first time, the transcription of type‐2 cytokine‐genes in the skin of dogs with AD. Future experiments investigating the cellular origin and dynamics of allergic cytokine‐gene transcription are needed to confirm whether or not canine AD could be considered an immunological model for a human disease.
Melanocytes adhere to and synthesize laminin‐5 in vitro
Authors: Scott G. A. , Cassidy L. , Tran H. , Rao S. K. , Marinkovich M. P.
Published: May 2007

Abstract: Melanocytes arise from the neural crest, migrate to the skin, and can be detected in the basal layer of the epidermis in skin biopsies of human fetuses as early as 11 weeks gestational age. During post‐natal life, melanocytes reside at the basal layer of the epidermis, but the ligands to which they attach are unknown. Laminin‐5 is a component of anchoring filaments of the lamina lucida of the epidermal basement membrane. In this report we show that human melanocytes adhere to purified laminin‐5 to a level comparable with normal human keratinocytes. Blocking antibodies to the 165 kDa subunit of laminin‐5 significantly inhibited fetal and neonatal melanocyte attachment to the surface of saltsplit skin, which exposes laminin‐5 on its surface, suggesting that laminin‐5 is a ligand for melanocyte attachment to the basement membrane in vivo. Western blotting of concentrated culture supernatant of fetal and neonatal melanocytes with anti‐laminin‐5 antibodies demonstrated a single immunoreactive band of the expected size of laminin‐5. In contrast, 3 human metastatic melanoma cell lines did not produce laminin‐5. Immunofluorescence microscopy with antibodies to each of the three chains of laminin‐5 confirmed the presence of laminin‐5 in a peri‐cellular distribution around melanocytes, but not melanoma cells. Our results suggest that laminin‐5 may be a ligand for normal human melanocytes in the basement membrane, and that loss of laminin‐5 production by melanoma cells may be a marker for malignant transformation.
Basal cell carcinoma – an in‐vivo model of human tumour microcirculation?
Authors: Bedlow A. J. , Stanton A. W. B. , Cliff S. , Mortimer P. S.
Published: May 2007

The role of angiogenesis in tumour growth and metastasis is well established. However, investigation off tumour microcirculation to date have used either biopsy material from human tumours, or animal models in vivo. we have studied the tumour microcirculation in vivo in human skin cancers using video‐microscopy to examine 12 basal cell carcinomas (BCCs) on the head andneck of 11 patients, and compared the vessels with those seen in the peri‐lesional skin, and in normal control skin on the oppsite side of the body. The vessels seen within the BCCs were markedly abnormal qualitiatively, forming bizarre, disorganized patterns. Quantitative analysis revealed that the mean diameter (+standard deviation) of the largest vessel was significantly greater within the BCC (0.086+0.029 mm) than that in the control skin (0.034+0.012 mm) (P<0.001). The area fraction, a measure of the area a tissue occupied by vessels, was increased highly significantly within the BCCs (0.158+0.038) compared with both peri‐lesional skin (0.029+0.012) and control skin (0.027+0.010) (P0.001). Length density, the length of blood vessel per unit area of tissue, was also highly significantly greater within the lesion (210.22+66.05 cm−1) compared to peri‐lesional (27.10+ 15.67 cm−1) and control skin (28.27+15.81 cm−1) (P<0.001). This is the first study to have demonstrated that BCCs possess a distinct tumour microcirculation which can be observed directly, and assessed quantitatively. Prospective studies of tumour progression, possibly after intervention with angiogenesis inhibitors, are possible
Alopecia areata: an autoimmune disease?
Authors: McElwee K. J. , Tobin D. J. , Bystryn J.‐C. , King L. E. , Sundberg J. P.
Published: May 2007

Abstract: A wide range of hypotheses such as focal infection, trophoneur‐ oses, and endocrine dysfunction, have been previously proposed to explain the pathogenesis of alopecia areata (AA). Currently, the most widely held belief is that AA is an autoimmune disease with cellular and/or humoral immunity directed against anagen hair follicle antigen(s). However, until recently evidence in support of an autoimmune mechanism of AA has been largely circumstantial. More fundamental evidence has recently been amassed in support of AA as an autoimmune disease by using animal models. These data include: 1) identification of cross‐species hair follicle specific IgG autoantibodies, 2) The ability to induce AA in an animal model with transfer of skin from affected to naive individuals, and 3) the induction of disease by transfer of lymphocytes to human skin grafted to severe combined immunodeficiency mutant mice. A review of the pre‐ vious and current data related to the autoimmune basis of AA is provided to put into perspective the future studies needed to definitively determine whether AA is an autoimmune disease.
Identification of citrulline residues in the V subdomains of keratin K1 derived from the cornified layer of newborn mouse epidermis
Authors: Senshu T. , Akiyama K. , Nomura K.
Published: May 2007

Abstract: Citrulline residues are detected in keratins and filaggrin in the cornified layers of mammalian epidermis. Such citrulline residues are formed by the enzymatic deimination of arginine residues by peptidylarginine deiminase (EC 3.5.3.15). Major deiminated keratins are thought to be partially degraded/disulfide‐cross‐linked keratin K1 based on the immunoblotting profiles. In order to obtain more definitive evidence of the deimination of keratin K1 and also to investigate its functional significance, we attempted to identify its preferred acting sites of peptidylarginine deiminase. A partially degraded keratin K1 fraction obtained from the cornified layer of newborn mouse epideermis was subjected to limited proteolytic cleavages, and the resulting deiminated peptides were fractionated by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis or reverse‐phase high‐performance liquid chromatography for N‐terminal sequencing and/or amino acid analysis. At least two sites were identified, one in the V1 and the other in the V2 subdomains of keratin K1. An undecapeptide sequence covering the latter shows about 70% homology with an undecapeptide sequence in the V2 subdomain of human K1, a presumptive site of deimination. We speculated that the deimination of arginine residues in these subdomains might modulate their interactions with epidermal proteins other than keratins and filaggrin during the terminal stage of epidermal differentiation.
Cytokine modulation of type XV collagen gene expression in human dermal fibroblast cultures
Authors: Kivirikko S. , Mauviel A. , Pihlajaniemi T. , Uitto J.
Published: May 2007

The expression of type XV collagen was studied in cultured human dermal fibroblasts exposed to transforming growth factor‐β (TGF‐β), tumor necrosis factor‐α (TNF‐α) or interleukin‐1β (IL‐1β), cytokines which have been shown previously to alter the expression of several extracellular matrix genes. TGF‐β enhanced the expression of the type XV collagen gene (COL15A1) in a time‐dependent manner, up to 4.3‐fold after 24 h of incubation, whereas TNF‐α and IL‐1β reduced the mRNA steady‐state levels by 32 and 80%, respectively. When TGF‐β and TNF‐α were added together to the cultures, the stimulatory effect of TGF‐β on type XV collagen gene expression was abrogated, indicating antagonistic modulation by these 2 cytokines. These data suggest that the cytokines tested in this study may contribute to the regulation of type XV collagen synthesis in a variety of tissues which have recently been shown to express this particular collagen gene.
Purification of mast cell proteases from murine skin
Authors: Algermissen B. , Laubscher J. C. , Bauer F. , Henz B. M.
Published: May 2007

Abstract: Different subpopulations of mast cells are characterized by their abundant contents of either tryptase or in addition chymase. These two neutral proteases are found in mast cells and may thus hold a key to the understanding of mast cell dependent reactions. Such studies are however hampered by the lack of readily available supplies of chymase. We have therefore studied the simultaneous purification of both proteases from hairless moro hr/hr mouse skin, using a sequence of salt extractions and chromatographic separations. After three steps of extraction, a 13‐fold purification with an 82% yield was obtained for tryptase and a 15‐fold purification with a 90% yield for chymase. Further one step purification on conventional sephadex, sephacryl and octyl sepharose columns was unsatisfactory because of further protein contamination of the fractions. Heparin affinity chromatography caused a high loss of tryptase and residual protein contamination. Gradient elution on a benzamidine sepharose 6B column resulted however in a single, low yield (17.9%) tryptase peak and a broader, high yield (>90%) chymase peak, and a 34% yield high purity fraction. The proteases thus purified exhibited their typical inhibitor profile. On Western blot analysis and on autoradiography in the presence of the serine protease inhibitor diisopropylfuorophosphate (DFP), only one 28 kD molecule with chymase activity was identified, whereas a broad 32‐38 kD band of tryptase monomers was noted. Taken together, these data show that, after salt extraction and a single benzamidine affinity chromatography step, both mast cell chymase and tryptase can be separated and in case of chymase also highly purified, allowing thus for the study of biological activities of this molecule.
Adverse events associated with intravenous iron infusion (low‐molecular‐weight iron dextran and iron sucrose): a systematic review
Authors: CRITCHLEY JULIA , DUNDAR YENAL
Published: May 2007

Intravenous iron administration is an effective method of treating iron deficiency anemia, but there have been concerns about adverse side effects, particularly serious events such as anaphylactic reaction. Several different forms of intravenous iron are available, but few studies have attempted to compare the frequency of adverse events.

We carried out a systematic review to assess the frequency of adverse drug events (ADEs) associated with (i) low‐molecular‐weight intravenous iron dextran and (ii) iron sucrose. We searched several electronic databases; two reviewers screened all studies identified and extracted data. We included 60 studies, but few directly compared adverse events associated with two or more forms of iron, and most were not specifically designed to evaluate adverse events.

In general, with the exception of high‐molecular‐weight iron dextran (HMWID), serious or life‐threatening adverse events appeared rare. Several studies showed lower risks of ADEs on low‐molecular‐weight iron dextran (LMWID) compared with HMWID, and one large review found a reduced risk on LMWID compared with iron gluconate. Two studies showed little difference between iron sucrose and iron gluconate, and two further studies had similar rates of adverse drug events between iron sucrose and LMWID; however, the sample size for most of these studies was too small to draw firm conclusions. Adequately powered direct comparisons of different forms of intravenous iron are required to assess the safety profiles.
Intraoperative surgical considerations for enhanced recovery after elective colonic surgery
Authors: HENDRY PAUL , FEARON KENNETH C. H.
Published: May 2007

Careful planning of the intraoperative stage of the surgical stay plays an important role in achieving progress through the perioperative component of a multimodal care pathway. This period will play a significant part of the patient’s hospital experience and may dictate the ability to achieve the postoperative targets of an enhanced recovery program. A review of the available evidence demonstrates where benefits can be made to contribute to the overall progress of the patient’s recovery. Elements considered include: wound siting and care, minimal access techniques, use of diathermy, insertion of drains and catheters, and aspects of surgical techniques. These areas, when combined as part of an ‘enhanced recovery after surgery’ program, should contribute to a more rapid patient recovery without any increase in complications.
Towards an Integrated Approach in Supporting Microbiological Food Safety Decisions
Authors: Havelaar A. H. , Bräunig J. , Christiansen K. , Cornu M. , Hald T. , Mangen M.‐J. J. , Mølbak K. , Pielaat A. , Snary E. , Van Pelt W. , Velthuis A. , Wahlström H.
Published: May 2007

Decisions on food safety involve consideration of a wide range of concerns including the public health impact of foodborne illness, the economic importance of the agricultural sector and the food industry, and the effectiveness and efficiency of interventions. To support such decisions, we propose an integrated scientific approach combining veterinary and medical epidemiology, risk assessment for the farm‐to‐fork food chain as well as agricultural and health economy. Scientific advice is relevant in all stages of the policy cycle: to assess the magnitude of the food safety problem, to define the priorities for action, to establish the causes for the problem, to choose between different control options, to define targets along the food chain and to measure success.
Regional and tissue specific transcript signatures of ion channel genes in the non‐diseased human heart
Authors: Gaborit Nathalie , Le Bouter Sabrina , Szuts Viktoria , Varro Andras , Escande Denis , Nattel Stanley , Demolombe Sophie
Published: May 2007

The various cardiac regions have specific action potential properties appropriate to their electrical specialization, resulting from a specific pattern of ion‐channel functional expression. The present study addressed regionally defined differential ion‐channel expression in the non‐diseased human heart with a genomic approach. High‐throughput real‐time RT‐PCR was used to quantify the expression patterns of 79 ion‐channel subunit transcripts and related genes in atria, ventricular epicardium and endocardium, and Purkinje fibres isolated from 15 non‐diseased human donor hearts. Two‐way non‐directed hierarchical clustering separated atria, Purkinje fibre and ventricular compartments, but did not show specific patterns for epicardium versus endocardium, nor left‐ versus right‐sided chambers. Genes that characterized the atria (versus ventricles) included Cx40, Kv1.5 and Kir3.1 as expected, but also Cav1.3, Cav3.1, Cavα2δ2, Navβ1, TWIK1, TASK1 and HCN4. Only Kir2.1, RyR2, phospholamban and Kv1.4 showed higher expression in the ventricles. The Purkinje fibre expression‐portrait (versus ventricle) included stronger expression of Cx40, Kv4.3, Kir3.1, TWIK1, HCN4, ClC6 and CALM1, along with weaker expression of mRNA encoding Cx43, Kir2.1, KChIP2, the pumps/exchangers Na+,K+‐ATPase, NCX1, SERCA2, and the Ca2+‐handling proteins RYR2 and CASQ2. Transcripts that were more strongly expressed in epicardium (versus endocardium) included Cav1.2, KChIP2, SERCA2, CALM3 and calcineurin‐α. Nav1.5 and Navβ1 were more strongly expressed in the endocardium. For selected genes, RT‐PCR data were confirmed at the protein level. This is the first report of the global portrait of regional ion‐channel subunit‐gene expression in the non‐diseased human heart. Our data point to significant regionally determined ion‐channel expression differences, with potentially important implications for understanding regional electrophysiology, arrhythmia mechanisms, and responses to ion‐channel blocking drugs. Concordance with previous functional studies suggests that regional regulation of cardiac ion‐current expression may be primarily transcriptional.
Electrophysiological characterization of vagal afferents relevant to mucosal nociception in the rat upper oesophagus
Authors: Lennerz J. K. M. , Dentsch C. , Bernardini N. , Hummel T. , Neuhuber W. L. , Reeh P. W.
Published: May 2007

Emerging evidence indicates a nociceptive role of vagal afferents. A distinct oesophageal innervation in the rat, with muscular and mucosal afferents travelling predominantly in the recurrent (RLN) and superior laryngeal nerve (SLN), respectively, enabled characterization of mucosal afferents with nociceptive properties, using novel isolated oesophagus–nerve preparations. SLN and RLN single‐fibre recordings identified 55 and 14 units, respectively, with none conducting faster than 8.7 m s−1. Mucosal response characteristics in the SLN distinguished mechanosensors (n= 13), mechanosensors with heat sensitivity (18) from those with cold sensitivity (19) and a mechanoinsensitive group (5). The mechanosensitive fibres, all slowly adapting, showed a unimodal distribution of mechanical thresholds (1.4–128 mN, peak ∼5.7 mN). No difference in response characteristics of C and Aδ fibres was encountered. Mucosal proton stimulation (pH 5.4 for 3 min), mimicking gastro‐oesophageal reflux disease (GORD), revealed in 31% of units a desensitizing response that peaked around 20 s and faded within 60 s. Cold stimulation (15°C) was proportionally encoded but the response showed slow adaptation. In contrast, the noxious heat (48°C) response showed no obvious adaptation with discharge rates reflecting the temperature's time course. Polymodal (69%) mucosal units, > 30% proton sensitive, were found in each fibre category and were considered nociceptors; they are tentatively attributed to vagal nerve endings type I, IV and V, previously morphologically described. All receptive fields were mapped and the distribution indicates that the posterior upper oesophagus may serve as a ‘cutbank’, detecting noxious matters, ingested or regurgitated, and triggering nocifensive reflexes such as bronchoconstriction in GORD.
Spreading dilatation to luminal perfusion of ATP and UTP in rat isolated small mesenteric arteries
Authors: Winter Polly , Dora Kim A.
Published: May 2007

Levels of ATP achieved within the lumen of vessels suggest a key autacoid role. P2Y receptors on the endothelium may represent the target for ATP, leading to hyperpolarization and associated relaxation of vascular smooth muscle through the endothelium‐dependent hyperpolarizing factor (EDHF) pathway. EDHF signals radially from the endothelium to cause dilatation, and appears mechanistically distinct from the axial spread of dilatation, which we showed occurs independently of a change in endothelial cell Ca2+ in rat mesenteric arteries. Here we have investigated the potential of P2Y receptor stimulation to evoke spreading dilatation in rat resistance small arteries under physiological pressure and flow. Triple cannulation of isolated arteries enables focal application of purine and pyrimidine nucleotides to the endothelium, avoiding potential complicating actions of these agents on the smooth muscle. Nucleotides were locally infused through one branch of a bifurcation, causing near maximal local dilatation attributable to EDHF. Dilatation then spread rapidly into the adjacent feed artery and upstream against the direction of luminal flow, sufficient to increase flow into the feed artery. The rate of decay of this spreading dilatation was identical between nucleotides, and matched that to ACh, which acts only on the endothelium. In contrast, focal abluminal application of either ATP or UTP at the downstream end of cannulated arteries evoked constriction, which only in the case of ATP was also associated with modest spread of dilatation. The non‐hydrolysable ADP analogue, ADPβS, acting at P2Y1 receptors, caused robust local and spreading dilatation responses whether applied to the luminal or abluminal surface of pressurized arteries. Dilatation to nucleotides was sensitive to inhibition with apamin and TRAM‐34, selective blockers of small‐ and intermediate‐conductance Ca2+‐activated K+ channels, respectively. These data demonstrate that direct luminal stimulation of P2Y receptor on the endothelium of rat mesenteric arteries leads to marked spreading dilatation and thus suggests that circulating purines and pyrimidines may act as important regulators of blood flow.
Passivation layer on polyimide deposited by combined plasma immersion ion implantation and deposition and cathodic vacuum arc technique
Authors: Han Z. J. , Tay B. K. , Sze J. Y. , Ha P. C. T.
Published: May 2007

A thin passivation layer of aluminum oxide was deposited on polyimide by using the combined plasma immersion ion implantation and deposition (PIII&D) and cathodic vacuum arc technique. X-ray photoelectron spectroscopy C 1s spectra showed that the carbonyl bond (CO) and ether group (C–O–C and C–N–C) presented in pristine polyimide were damaged by implantation of aluminum ions and deposition of an aluminum oxide passivation layer. O 1s and Al 2p spectra confirmed the formation of a thin aluminum oxide passivation layer. This passivation layer can be implemented in aerospace engineering where polyimide may suffer degradation from fast atomic oxygen in the low-earth-orbit environment. To test the protection of this passivation layer to energetic oxygen ions, a plasma-enhanced chemical vapor deposition system was used to simulate the oxygen-ion irradiation, and the results showed that a higher weight occurred for passivated samples compared to pristine ones. X-ray diffraction showed that Al peaks were presented on the surface region, but no aluminum oxide peak was detected. The authors then concluded that Al clusters were formed in polyimide besides aluminum oxide, which was in an x-ray amorphous state. Furthermore, contact-angle measurements showed a reduced contact angle for passivated polyimide from a pristine value of 78° to 20° by using deionized water. Several discussions have been made on the surface chemical and structural property changes by using the combined PIII&D and cathodic vacuum arc technique.
Identification of important growth parameters for the development of high quality Alx>0.5Ga1−xN grown by metal organic chemical vapor deposition
Authors: Grandusky J. R. , Jamil M. , Jindal V. , Tripathi N. , Shahedipour-Sandvik F.
Published: May 2007

High quality Alx>0.5Ga1−xN layers were grown on (0001) sapphire substrates by metal organic chemical vapor deposition utilizing an AlN nucleation layer. The growth conditions of the nucleation layer were observed to have a large impact on both the surface morphology and the crystalline quality of the AlxGa1−xN layers. Low temperature nucleation layers with an optimum thickness of ∼15nm gave the best quality AlxGa1−xN layers. Additionally the annealing of the nucleation layer was seen to have a dramatic effect on the crystalline quality of the overgrown AlxGa1−xN layers. The quality of the films as measured by atomic force microscopy and x-ray diffraction was largely independent of the V/III ratios of the AlxGa1−xN layers, although Al incorporation and growth rate were affected. Two distinct regimes were identified for the Al incorporation in the overgrown AlxGa1−xN as a function of ammonia flow rate; the Al incorporation first decreases with increase in the ammonia flow rate and then increases with a continued increase in the ammonia flow rate. It is shown that the residence time of the species in the growth system controls the amount of the precursor prereaction independently of the actual flow rates and V/III ratio affecting the Al incorporation in the solid phase.
Sputter deposited electroluminescent zinc sulfide thin films doped with rare earths
Authors: Glass William , Kale Ajay , Shepherd Nigel , Davidson Mark , DeVito David , Holloway Paul H.
Published: May 2007

The effects of deposition conditions on the physical properties and threshold voltages of ZnS alternating current thin film electroluminescent (ACTFEL) phosphors are reported. The ZnS thin films were deposited by rf magnetron cosputtering of both a pure ZnS and a ZnS target doped with either 1.5mol% ErF3, NdF3, or TmF3, and EL peaks in both the visible and near infrared (NIR) were observed. The substrate temperature during deposition was varied between 140 and 190°C, and the highest NIR EL intensity was measured from as-deposited films at 140°C. Energy dispersive x-ray analysis was used to determine the rare earth concentrations between 1.0 and 2.6at.%, and the maximum emission was at ∼0.8–1at.%. The EL intensity decreased at higher concentrations due to poor crystallinity and decreased at lower concentrations due to lower rates of excitation. The threshold voltage and phosphor thickness for these ACTFEL devices both decreased as the deposition temperature was increased due to re-evaporation of the incongruently sputter transported zinc and sulfur. Electrical data confirmed that the optical threshold voltage for both NIR and visible emission were equal to one another and to the electrical breakdown voltage, indicating that at breakdown the energies of ballistic electrons are sufficient to excite both visible and infrared emissions.
Improvement of corrosion resistance of transparent conductive multilayer coating consisting of silver layers and transparent metal oxide layers
Authors: Koike Katsuhiko , Yamazaki Fumiharu , Okamura Tomoyuki , Fukuda Shin
Published: May 2007

An optical filter for plasma display panel (PDP) requires an electromagnetic shield with very high ability. The authors investigated a transparent conductive multilayer coating consisting of silver (Ag) layers and transparent metal oxide layers. The durability of the multilayer sputter coating, including the silver layer, is very sensitive to the surrounding atmosphere. For example, after an exposure test they found discolored points on the multilayer sputter coatings, possibly caused by migration of silver atoms in the silver layers. In their investigation, they modified the top surface of the multilayer sputter coatings with transition metals to improve the corrosion resistance of the multilayer coating. Specifically, they deposited transition metals 0.5–2nm thick on the top surface of the multilayer coatings by sputtering. They chose indium tin oxide (ITO) as the transparent metal oxide. They applied the multilayer sputter coatings of seven layers to a polyethylene terephthalate (PET) film substrate. A cross-sectional structure of the film with the multilayer coatings is PET film/ITO/Ag/ITO/Ag/ITO/Ag/ITO. They evaluated the corrosion resistance of the films by a salt-water immersion test. In the test, they immersed the film with multilayer coatings into salt water, and then evaluated the appearance, transmittance, and electrical resistance of the multilayer coatings. They investigated several transition metals as the modifying material, and found that titanium and tantalum drastically improved the resistance of the multilayer coatings to the salt-water exposure without a significant decline in transmittance. They also investigated the relation between elapsed time after deposition of the modifying materials and resistance to the salt water. Furthermore, they investigated the effects of a heat treatment and an oxide plasma treatment on resistance to the salt water.
Combined filtered cathodic arc etching pretreatment–magnetron sputter deposition of highly adherent CrN films
Authors: Ehiasarian A. P. , Anders A. , Petrov I.
Published: May 2007

CrN films were prepared on steel substrates by a hybrid method utilizing filtered cathodic arc for Cr ion pretreatment and magnetron sputtering for coating deposition. During pretreatment the substrates were biased to −1200V and exposed to filtered chromium plasma. The substrate-coating interface formed during the pretreatment contained a Cr-enriched modified layer with composition that was strongly influenced by the temperature of the substrate as observed by scanning transmission electron microscopy—energy dispersive spectroscopy. The modified layer had a nanocrystalline morphology and thickness of 15nm. The path of formation of the layer is linked to the combined action of implantation, diffusion, and resputtering. The resulting adhesion of 3μm thick CrN films was very high with scratch test critical load values of 83N. The morphology of the films was smooth without large scale defects and the microstructure was columnar. The coatings behaved well in dry sliding tests with very low wear coefficients of 2.3×10−16m3N−1m−1, which can be linked to the high adhesion and defect-free microstructure. The smooth coatings also had a high resistance to corrosion as demonstrated by potentiodynamic tests with particularly high pitting potentials of +800mV.
Photosynthesis and structure of electroless Ni–P films by synchrotron x-ray irradiation
Authors: Hsu Pei-Cheng , Wang Chang-Hai , Yang Tsung-Yeh , Hwu Yeu-Kuang , Lin Chao-Sung , Chen Chih-Hsiung , Chang Liu-Wen , Seol Seung-Kwon , Je Jung-Ho , Margaritondo G.
Published: May 2007

The authors describe an electroless deposition method for thin films, based on the irradiation by an x-ray beam emitted by a synchrotron source. Specifically, Ni–P films were deposited at room temperature. This synthesis is a unique combination of photochemical and electrochemical processes. The influence of the pH value on the formation and structural properties of the films was examined by various characterization tools including scanning electron microscopy, x-ray diffraction, and x-ray absorption spectroscopy. Real time monitoring of the deposition process by coherent x-ray microscopy reveals that the formation of hydrogen bubbles leads to a self-catalysis effect without a preexisting catalyst. The mechanisms underlying the deposition process are discussed in details.
Role of surface tension in copper electroplating
Authors: Chang Shih-Chieh , Wang Ying-Lang , Hung Chi-Cheng , Lee Wen-His , Hwang Gwo-Jen
Published: May 2007

This study demonstrates that the surface tension of plating solutions should be optimized to achieve a compromise between the gap-filling capability of copper electroplating and the formation of copper-void defects. The plating solution with lower surface tension has better gap filling but generates more air bubbles during copper electroplating. For a low-surface-tension electrolyte, the improvement in the gap-filling capability is caused by the enhancement in the ability of fluids to wet high-aspect-ratio features, whereas the increase in the formation of copper-void defects results from more air bubbles generated during the electroplating process. This study provides a model to describe the role of surface tension in copper electroplating.
Effects of in situ N2 plasma treatment on etch of HfO2 in inductively coupled Cl2∕N2 plasmas
Authors: Lin Chaung , Leou Keh-Chyang , Fan Yeou-Chung , Li Ting-Chieh , Chang Kuei-Hui , Lee Lurng-Shehng , Tzeng Pei-Jer
Published: May 2007

The etch selectivity of HfO2 to Si reported to date is poor. To improve the selectivity, one needs to either increase the etch rate of HfO2 or decrease the etch rate of Si. In this work, the authors investigate the etch selectivity of HfO2 in Cl2∕N2 plasmas. In particular, the effects of in situ N2 plasma treatment of HfO2 and Si were investigated. The silicon substrate was exposed to nitrogen plasma and was nitrided, which was confirmed by x-ray photoelectron spectroscopy. The nitrided Si etching was suppressed in Cl2∕N2 plasmas. The effectiveness of nitridation was studied with varying the plasma power, bias power, pressure, and N2 plasma exposure time. The results show that the etch resistance increased with increased power and decreased pressure. A minimum exposure time was required to obtain etch resistant property. The applied bias power increased the etch rate of Si substrate, so it should not be used during N2 plasma treatment. Fortunately, the etch rate of HfO2 was increased by the nitridation process. Therefore, HfO2∕Si selectivity can be improved by nitridation and became higher than 5 under proper exposure condition.
Sealing ultralow κ porous dielectrics with thin boron carbonitride films
Authors: Ahearn W. J. , Fitzpatrick P. R. , Ekerdt J. G.
Published: May 2007

Porous ultralow κ dielectric film pores were sealed by 1–5nm films of boron carbonitride, itself a dielectric. The BC0.9N0.07 films were deposited by chemical vapor deposition at 335°C on etched and ashed blanket films and patterned films of porous methyl silsesquioxane (PMSQ). The penetration of Ta through the boron carbonitride film and into the porous low κ substrate following exposure to TaF5 at 230°C, or TaSix growth from TaF5 and Si2H6 at 230°C, was used to test pore sealing. Tantalum profiles were evaluated using x-ray photoelectron spectroscopy depth profiling, back side secondary ion mass spectroscopy, and energy dispersive x-ray spectroscopy. A 3.9nm boron carbonitride film sealed PMSQ, which has an average pore diameter of 1.9nm before etching. The diffuse nature of the BC0.9N0.07-PMSQ interface in electron energy loss profile maps suggests that some of the BC0.9N0.07 penetrates into the PMSQ until the pore openings are pinched off as the sealing film deposits.
Chronological analysis of architectural and acoustical indices in music performance halls
Authors: Kwon Youngmin , Siebein Gary W.
Published: May 2007

This study aims to identify the changes in architectural and acoustical indices in halls for music performance built in the 18th through the 20th Centuries. Seventy-one halls are classified in five specific periods from the Classical Period (1751–1820) to the Contemporary Period (1981–2000) based on chronology in music and architectural acoustics. Architectural indices such as room shape, seating capacity, room volume, balcony configuration, and the like as well as acoustical indices such as RT, EDT, G, C80, IACC, and the like for the halls found in the literature are chronologically tabulated and statistically analyzed to identify trends and relationships in architectural and acoustical design for each of the historical periods identified. Some indices appear correlated with each other.
Measurement of sound power and absorption in reverberation chambers using energy density
Authors: Nutter David B. , Leishman Timothy W. , Sommerfeldt Scott D. , Blotter Jonathan D.
Published: May 2007

Reverberation chamber measurements typically rely upon spatially averaged squared pressure for the calculation of sound absorption, sound power, and other acoustic values. While a reverberation chamber can provide an approximately diffuse sound field, variations in sound pressure consistently produce uncertainty in measurement results. This paper explores the benefits of using total energy density or squared particle velocity magnitude (kinetic energy density) instead of squared pressure (potential energy density) for sound absorption and sound power measurements. The approaches are based on methods outlined in current ISO standards. The standards require a sufficient number of source-receiver locations to obtain suitable measurement results. The total and kinetic energy densities exhibit greater spatial uniformity at most frequencies than potential energy density, thus requiring fewer source-receiver positions to produce effective results. Because the total energy density is typically the most uniform of the three quantities at low frequencies, its use could also impact the usable low-frequency ranges of reverberation chambers. In order to employ total and kinetic energy densities for sound absorption measurements, relevant energy-based impulse responses were developed as part of the work for the assessment of sound field decays.
Effectiveness of computer-based auditory training in improving the perception of noise-vocoded speech
Authors: Stacey Paula C. , Quentin Summerfield A.
Published: May 2007

Five experiments were designed to evaluate the effectiveness of “high-variability” lexical training in improving the ability of normal-hearing subjects to perceive noise-vocoded speech that had been spectrally shifted to simulate tonotopic misalignment. Two approaches to training were implemented. One training approach required subjects to recognize isolated words, while the other training approach required subjects to recognize words in sentences. Both approaches to training improved the ability to identify words in sentences. Improvements following a single session (lasting 1–2h) of auditory training ranged between 7 and 12%pts and were significantly larger than improvements following a visual control task that was matched with the auditory training task in terms of the response demands. An additional three sessions of word- and sentence-based training led to further improvements, with the average overall improvement ranging from 13 to 18%pts. When a tonotopic misalignment of 3mm rather than 6mm was simulated, training with several talkers led to greater generalization to new talkers than training with a single talker. The results confirm that computer-based lexical training can help overcome the effects of spectral distortions in speech, and they suggest that training materials are most effective when several talkers are included.
Compensating for miter bends in cylindrical tubing
Authors: Coltman John W.
Published: May 2007

Miter bends in cylindrical tubing perturb wave propagation in a way that may alter the desired resonance properties in musical instruments. The nature of the perturbations and several methods of compensating for them at low frequencies are described.
Noise propagation in linear and nonlinear inverse scattering
Authors: Ghosh Roy Dilip N. , Roberts John , Schabel Matthias , Norton Stephen J.
Published: May 2007

The propagation of noise from the data to the reconstructed speed of sound image by inverse scattering within the framework of the Lippmann-Schwinger integral equation of scattering is discussed. The inversion algorithm that was used consisted in minimizing a Tikhonov functional in the unknown speed of sound. The gradient of the objective functional was computed by the method of the adjoint fields. An analytical expression for the inverse scattering covariance matrix of the image noise was derived. It was shown that the covariance matrix in the linear x-ray computed tomography is a special case of the inverse scattering matrix derived in this paper. The matrix was also analyzed in the limit of the linearized Born approximation, and the results were found to be in qualitative agreement with those recently reported in the literature for Born inversion using filtered backpropagation algorithm. Finally, the applicability of the analysis reported here to the obstacle problem and the physical optics approximation was discussed.
The effects of low- and high-frequency suppressors on psychophysical estimates of basilar-membrane compression and gain
Authors: Yasin Ifat , Plack Christopher J.
Published: May 2007

Physiological studies suggest that the increase in suppression as a function of suppressor level is greater for a suppressor below than above the signal frequency. This study investigated the pattern of gain reduction underlying this increase in suppression. Temporal masking curves (TMCs) were obtained by measuring the level of a 2.2-kHz sinusoidal off-frequency masker or 4-kHz on-frequency sinusoidal masker required to mask a brief 4-kHz sinusoidal signal at 10dB SL, for masker-signal intervals of 20–100ms. TMCs were also obtained in the presence of a 3- or 4.75-kHz sinusoidal suppressor gated with the 4-kHz masker, for suppressor levels of 40–70dB SPL. The decrease in gain (increase in suppression) as a function of suppressor level was greater with a 3-kHz suppressor than with a 4.75-kHz suppressor, in line with previous findings. Basilar membrane input-output (I/O) functions derived from the TMCs showed a shift to higher input (4-kHz masker) levels of the low-level (linear) portion of the I/O function with the addition of a suppressor, with partial linearization of the function, but no reduction in maximum compression.