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Sample records for psaa lamellar core

  1. Self-assembled particulate PsaA as vaccine against Streptococcus pneumoniae infection

    Directory of Open Access Journals (Sweden)

    Majela González-Miro

    2017-04-01

    Full Text Available Streptococcus pneumoniae is a human pathogen responsible for the majority of childhood pneumonia and media otitis cases worldwide. The diversity of its capsular polysaccharides (CPS results in more than 91 serotypes of which at least 23 are virulent. Various CPS conjugated to immunogenic carrier proteins are currently licensed and provide protection against the infection caused by the respective serotypes but not against new and emerging virulent serotypes. In this study, we considered the conserved protein antigen PsaA, the pneumococcal surface adhesin A, in order to overcome the limitations of CPS antigens. The PsaA was translationally fused to a polyhydroxybutyrate (PHB synthase which mediated production of PsaA displayed on PHB inclusions in recombinant Escherichia coli. This suggested that the PsaA fusion to the PHB synthase did not interfere with PHB synthase activity and its ability to mediate formation of nano-sized inclusions composed of a PHB core surrounded by the PHB synthase fused to PsaA. Isolated PHB beads showed a negative surface charge. Transmission electron microscopy analysis suggested that the PsaA fusion to the PHB synthase reduced the size of PHB beads from about 500 nm to 100 nm. The integrity and antigenicity of the fusion protein attached to isolated PHB beads was confirmed by SDS-PAGE, tryptic peptide fingerprinting analysis using MALDI-TOF-MS/MS and immunoblotting using a monoclonal anti-PsaA antibody. Mice immunized with PsaA displaying PHB beads produced high and specific IgG levels dominated by IgG1 isotype. While IgG1 titer were similar between soluble and insoluble PsaA, the IgG2 titers were strongly increased upon vaccination with insoluble PsaA i.e. PsaA displayed on PHB beads. Particulate PsaA-PHB beads elicited IgG antibodies recognizing PsaA in whole cell lysates of seven different serotypes of S. pneumoniae. This study suggested that PHB beads are suitable carriers for PsaA in order to induce a significant

  2. Analysis of Social and Emotional Development of Orphaned Youth in terms of Self Concept and Resilience: Study at Child Care Children's Home (PSAA Tunas Bangsa Pati

    Directory of Open Access Journals (Sweden)

    Santoso Santoso

    2017-08-01

    Full Text Available The purpose of this study is to describe the development of the Young Social da Emotional Self-concept and in terms of resilience in the PSAA Tunas Bangsa Pati. The method used is descriptive research with this type of development studies dab data obtained will be analyzed by cross sectional method. The results showed that the concept of self-possessed teenager PSAA is not good, it can be seen from the description of several indicators show that the concept of self-assessment of her teenage less well because many feel insecure and inferiority. Judging from the resilience, the general adolescent PSAA good enough. It can be seen from the emotion management capabilities of any events that are considered less menyengakan life. So overall it can be concluded that the social development of adolescents PSAA poorly and emotional development PSAA pretty good when viewed from the concept of self and resilience.

  3. Quantitative determination of proteins at nanogram levels by the resonance light-scattering technique with macromolecules nanoparticles of PS?AA

    Science.gov (United States)

    Wang, Leyu; Chen, Hongqi; Li, Ling; Xia, Tingting; Dong, Ling; Wang, Lun

    2004-03-01

    The polystyrene-acrylic acid (PS-AA) nanoparticles have been prepared by ultrasonic polymerization, characterized by FT-IR and TEM. It is the first report on the determination of proteins with macromolecules nanoparticles of PS-AA by resonance light-scattering (RLS). At pH 6.9, the RLS of macromolecules nanoparticles of PS-AA can be enhanced by proteins. Based on this, a novel quantitative assay of proteins at the nanogram levels has been proposed. At pH 6.9, the RLS signals of PS-AA were greatly enhanced by proteins in the region of 250-700 nm characterized by the peak at 342 nm. Under optimal conditions, the linear ranges of the calibration curves were 0.02-11.0 μg ml -1, 0.04-10.0 μg ml -1 and 0.03-10.0 μg ml -1 for γ-globulin (γ-IgG), bovine serum albumin (BSA) and human serum albumin (HSA), respectively. The detection limits were 16.0 ng ml -1, 19.0 ng ml -1, and 15.0 ng ml -1 for γ-IgG, BSA and HSA, respectively. The method has been applied to the analysis of total proteins in human serum samples collected from the hospital and the results were in good agreement with those reported by the hospital, which indicates that the method presented here is not only sensitive, simple, but also reliable and suitable for practical application.

  4. Lamellar Ichthyosis with Bilateral Ectropion

    African Journals Online (AJOL)

    . Clin Ophthalmol 2009;3:611‑3. 4. Cruz AA, Menezes FA, Chaves R, Pinto Coelho R, Velasco EF,. Kikuta H. Eyelid abnormalities in lamellar ichthyoses. Ophthalmology. 2000;107:1895‑8. 5. Cinar Y, Selcuk CT, Cingu AK, Turkcu FM, Yuksel H, ...

  5. Molecular phylogeny and evolution of the order Tribonematales (Heterokonta, Xanthophyceae) based on analysis of plastidial genes rbcL and psaA.

    Science.gov (United States)

    Maistro, Silvia; Broady, Paul A; Andreoli, Carlo; Negrisolo, Enrico

    2007-05-01

    Tribonematales is an order of filamentous algae in the class Xanthophyceae (Heterokonta). Few molecular studies, all with a limited taxon sampling, have previously investigated its evolutionary history and phylogenetic relationships. We sequenced the chloroplast-encoded rbcL and psaA genes of several tribonematalean species and of several coccoid and siphonous forms that previous studies revealed to be strictly related to Tribonematales. Multiple alignments included mostly new sequences obtained from 42 taxa. Phylogenetic reconstructions were performed using the maximum likelihood method. The rbcL and psaA data sets were analyzed independently and combined in a single multiple alignment. Neither rbcL nor psaA genes showed intraspecific sequence variation. The former proved to be a better diagnostic marker than the latter for characterization of species. We explored effects produced on phylogenetic outcomes by selected genes. Congruent results were obtained from analyses performed on single gene multiple alignments as well as on the combined data set. There is strong statistical support for trees that show several currently recognized taxonomic groups to be polyphyletic. The siphonous orders Botrydiales and Vaucheriales do not form a clade. Botrydiales and Tribonematales are polyphyletic as are the families Botrydiaceae, Centritractaceae and Tribonemataceae and the genera Xanthonema and Bumilleriopsis. We tentatively define new boundaries of the Tribonematales to include both coccoid and filamentous species having a bipartite cell wall and also the siphonous members of the genus Botrydium. Also, our results support morphological convergence at all taxonomic ranks in the evolution of the Xanthophyceae.

  6. Morphological instabilities of lamellar eutectics

    Energy Technology Data Exchange (ETDEWEB)

    Karma, A.; Sarkissian, A. [Northeastern Univ., Boston, MA (United States). Physics Dept.

    1996-03-01

    The authors present the results of a numerical study based on the boundary integral technique of interfacial pattern formation in directional solidification of thin-film lamellar eutectics at low velocity. Microstructure selection maps that identify the stability domains of various steady-state and nonsteady-state growth morphologies in the spacing-composition ({lambda} {minus} C{sub 0}) plane are constructed for the transparent organic alloy CBr{sub 4}-C{sub 2}Cl{sub 6} and for a model eutectic alloy with two solid phases of identical physical properties. In CBr{sub 4}-C{sub 2}Cl{sub 6}, the basic set of instabilities that limit steady-state growth is richer than expected. It consists of three primary instabilities, two of which are oscillatory, which bound the domain of the commonly observed axisymmetric lamellar morphology, and two secondary oscillatory instabilities, which bound the domain of the nonaxisymmetric (tilted) lamellar morphology. Four stable oscillatory microstructures, at least three of which have been seen experimentally, are predicted to occur in unstable regimes. In the model alloy, the structure is qualitatively similar, except that a stable domain of tilted steady-state growth is not found, in agreement with previous random-walk simulations. Furthermore, the composition range of stability of the axisymmetric morphology decreases sharply with increasing spacing away from minimum undercooling but extends further off-eutectic than predicted by the competitive growth criterion. In addition, oscillations with a wavelength equal to two {lambda} lead to lamella termination at a small distance above the onset of instability. The implications of these two features for the eutectic to dendrite transition are examined with the conclusion that in the absence of heterogeneous nucleation, this transition should be histeritic at small velocity and temperature gradient.

  7. Identification of Streptococcus pneumoniae lytA, plyA and psaA genes in pleural fluid by multiplex real-time PCR.

    Science.gov (United States)

    Sanz, Juan Carlos; Ríos, Esther; Rodríguez-Avial, Iciar; Ramos, Belén; Marín, Mercedes; Cercenado, Emilia

    2017-08-14

    The aim was to evaluate the utility of a multiplex real-time PCR to detect Streptococcus pneumoniae lytA, plyA and psaA genes in pleural fluid (PF). A collection of 81 PF samples was used. Sixty were considered positive for S. pneumoniae according to previous results (54 by an in-house lytA gene PCR and eight by universal rRNA PCR). The sensitivity for detection of the lytA, plyA and psaA genes by multiplex PCR was 100% (60/60), 98.3% (59/60) and 91.7% (55/60), respectively. The detection of all three genes was negative in 21 samples formerly confirmed as negative for S. pneumoniae (100% specificity) by the other procedures (9 by in-house lytA PCR and 12 by rRNA PCR). The use of this multiplex PCR may be a useful option to identify S. pneumoniae directly in PF samples. Copyright © 2017 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

  8. CORE

    DEFF Research Database (Denmark)

    Krigslund, Jeppe; Hansen, Jonas; Hundebøll, Martin

    2013-01-01

    different flows. Instead of maintaining these approaches separate, we propose a protocol (CORE) that brings together these coding mechanisms. Our protocol uses random linear network coding (RLNC) for intra- session coding but allows nodes in the network to setup inter- session coding regions where flows...... intersect. Routes for unicast sessions are agnostic to other sessions and setup beforehand, CORE will then discover and exploit intersecting routes. Our approach allows the inter-session regions to leverage RLNC to compensate for losses or failures in the overhearing or transmitting process. Thus, we...... increase the benefits of XORing by exploiting the underlying RLNC structure of individual flows. This goes beyond providing additional reliability to each individual session and beyond exploiting coding opportunistically. Our numerical results show that CORE outperforms both forwarding and COPE...

  9. Lamellar multilayer hexadecylaniline-modified gold nanoparticle ...

    Indian Academy of Sciences (India)

    Abstract. Organization of hexadecylaniline (HDA)-modified colloidal gold particles at the air–water interface and the formation thereafter of lamellar, multilayer films of gold nanoparticles by the Langmuir–Blodgett technique is described in this paper. Formation of HDA-capped gold nanoparticles is accomplished by a simple.

  10. Rod and lamellar growth of eutectic

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    M. Trepczyńska-Łent

    2010-04-01

    Full Text Available The paper presents adaptation problem of lamellar growth of eutectic. The formation of rod eutectic microstructure was investigated systematically. A new rod eutectic configuration was observed in which the rods form with elliptical cylindrical shape. A new interpretation of the eutectic growth theory was proposed.

  11. Lamellar multilayer hexadecylaniline-modified gold nanoparticle ...

    Indian Academy of Sciences (India)

    Organization of hexadecylaniline (HDA)-modified colloidal gold particles at the air-water interface and the formation thereafter of lamellar, multilayer films of gold nanoparticles by the Langmuir-Blodgett technique is described in this paper. Formation of HDA-capped gold nanoparticles is accomplished by a simple biphasic ...

  12. Sclerocorneal Intrastromal Lamellar Keratoplasty for Pellucid Marginal Degeneration.

    Science.gov (United States)

    Guindolet, Damien; Petrovic, Alexandra; Doan, Serge; Cochereau, Isabelle; Gabison, Eric E

    2016-06-01

    Surgical management of advanced pellucid marginal degeneration is challenging. To correct both corneal thinning and induced corneal astigmatism, we propose a modified intrastromal lamellar sclero-keratoplasty. Corneal thinning was mapped using perioperative optical coherence tomography (OCT). Then through a scleral tunnel, an intrastromal pocket was created by stromal lamellar dissection under OCT guidance. A 300 μm-thick stromal lamellar graft was inserted in that pocket before closing the sclera to increase vertical median keratometry. Intrastromal lamellar sclero-keratoplasty enabled corneal thinning correction and increased corneal astigmatism correction (-11.6 diopters) without complications. Intrastromal lamellar keratoplasty with scleral tunnel is efficient in PMD. Corneal thinning is corrected with the intrastromal lamellar keratoplasty, and scleral tunnel closure allows increased corneal astigmatism correction. Perioperative OCT guidance allows better detection of the diseased cornea and is helpful for the lamellar dissection.

  13. Alternaria Keratitis after Deep Anterior Lamellar Keratoplasty

    OpenAIRE

    Mekhla Naik; Mohd. Shahbaaz,; Jay Sheth; Sunderamoorthy, S. K.

    2014-01-01

    To describe a case of Alternaria keratitis in a 30-year-old male patient who presented with bilateral vascularised central corneal opacity and underwent deep anterior lamellar keratoplasty (DALK) in the left eye. Patient was treated for recurrent epithelial defect with a bandage contact lens in the follow-up visits after DALK. Subsequently, patient presented with pigmented fungal keratitis, which on culture examination of the corneal scrapping demonstrated Alternaria species. Patient had to u...

  14. Refractory Trichophyton rubrum infection in lamellar ichthyosis.

    Science.gov (United States)

    Scheers, Christel; Andre, Josette; Thompson, Curtis; Rebuffat, Elisabeth; Harag, Saadia; Kolivras, Athanassios

    2013-01-01

    A 10-month-old boy with congenital lamellar ichthyosis presented with a chronic Trichophyton rubrum infection. There was no history of atopy or immunosuppression, and examination revealed high total immunoglobulin E (IgE) with a positive specific IgE for T. rubrum. Multiple treatments with fluconazole were necessary to control the infection. T. rubrum is present worldwide and is responsible for the vast majority of chronic dermatophytosis. Lamellar ichthyosis is a risk factor for chronic dermatophytosis because of excessive keratin and the barrier defect. A delayed-type hypersensitivity reaction to T. rubrum is associated with cure, whereas immediate hypersensitivity and IgE are not protective and may lead to chronic infection. Atopy and the Th2 profile therefore seem to be associated with chronic dermatophytosis. The association between ichthyosis and atopy is well documented. T. rubrum also has an interesting ability to evade immunity, which helps explain the chronic infection. Finally, in ichthyosis, it is likely that fluconazole has difficulty penetrating the acanthotic stratum corneum, which explains treatment failure. We report this case to alert clinicians to the possible association between lamellar ichthyosis and chronic dermatophytosis and to report the difficulties of management. © 2013 Wiley Periodicals, Inc.

  15. Physical and mechanical properties of lamellar compounds of graphite

    OpenAIRE

    Костиков, Александр Анатольевич; Довгаль, Анна Николаевна; Черномаз, Владимир Николаевич; Кузнецов, Андрей Андреевич

    2013-01-01

    In this paper physical, mechanical and thermophysical properties of lamellar graphite compounds with various intercalants have been studied as a function of temperature and oxidants. The focus of the study was the influence of various factors on lamellar graphite compounds parameters, namely: elongation of samples, thermal expansion coefficient, thermal conductivity. The following factors have been considered: oxidant concentration in the synthesis of lamellar graphite compounds, the particle...

  16. A Case Report of Ichthyosis Lamellar Syndrome

    Directory of Open Access Journals (Sweden)

    Gh. Eshghi

    2014-04-01

    Full Text Available Introduction: Ichthyosis lamellar syndrome is a rare genodermatosis and in most families is inherited as an autosomal recessive trait because of transglutaminase-1 deficiency. Case Report: Our patient was a 6 year old girl and she was the result of consanguinity. She had large plate-like scales. The scales had mosaic-like pattern and erythroderma was absent. Tautness of her facial skin was associated with ectropion and eclabion and hypoplasia of auricular cartilages. She had scarring alopecia because of taut skin (specially at the periphery of scalp. She also had palmoplantar keratoderma and secondary nail dystrophy and thanked nails. Her parents also gave us the history of heat intolerance and it is because of interaepi-dermal constriction of sweat ducts. Our patient had the history of recurrent ear infections and it is because of accumulation of scales in the external ear. Conclusion: Our patient underwent a biopsy and based on our clinical findings her diagnosis was lamellar ichthyosis. (Sci J Hamadan Univ Med Sci 2014; 21 (1:76-79

  17. Deep anterior lamellar keratoplasty in keratoconus

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    Nikolić Ljubiša

    2011-01-01

    Full Text Available Introduction. Deep anterior lamellar keratoplasty (DALK is intended for the surgical treatment of corneal pathology without the involvement of the endothelium. Sparing of the healthy host endothelium for lifetime is of utmost importance in young patients. Therefore, keratoconus is among the main indications for DALK. Outline of Cases. Two men, 22 and 28 years of age, underwent DALK for the treatment of progressive keratoconus, with low visual acuity, impossible to be corrected with gas-permeable contact lenses, due to the extreme conical protrusion of the cornea. Baring of Descemet’s membrane was achieved with lamellar dissection and peeling off the stroma. An 8.5 mm graft without the endothelium was sutured into an 8.0 mm bed. Both grafts remained clear and attached, without either ocular surface pathology or problems arising from sutures. The best corrected visual acuity was 20/25 and 20/40, with the astigmatism of 2.5 and 3.0 diopters, respectively. The follow-up was one year. Conclusion. This is the first presentation of DALK in our literature. The restoration of corneal transparency and stability, with sparing of the host endothelium, has put DALK among successful corneal tranplantation procedures. Together with Descemet stripping endothelial keratoplasty, which already accounts for almost a half of all our keratoplasties, it offers an alternative to penetrating keratoplasty.

  18. Alternaria keratitis after deep anterior lamellar keratoplasty.

    Science.gov (United States)

    Naik, Mekhla; Mohd Shahbaaz; Sheth, Jay; Sunderamoorthy, S K

    2014-01-01

    To describe a case of Alternaria keratitis in a 30-year-old male patient who presented with bilateral vascularised central corneal opacity and underwent deep anterior lamellar keratoplasty (DALK) in the left eye. Patient was treated for recurrent epithelial defect with a bandage contact lens in the follow-up visits after DALK. Subsequently, patient presented with pigmented fungal keratitis, which on culture examination of the corneal scrapping demonstrated Alternaria species. Patient had to undergo a repeat DALK as the keratitis did not resolve with medical therapy alone. Patient did not have a recurrence for 11 months following the regraft. This case report highlights the importance of considering the Alternaria species as a possibile cause of non-resolving fungal keratitis after DALK.

  19. Extended constitutive laws for lamellar phases

    Directory of Open Access Journals (Sweden)

    Chi-Deuk Yoo

    2013-10-01

    Full Text Available Classically, stress and strain rate in linear viscoelastic materials are related by a constitutive relationship involving the viscoelastic modulus G(t. The same constitutive law, within Linear Response Theory, relates currents of conserved quantities and gradients of existing conjugate variables, and it involves the autocorrelation functions of the currents in equilibrium. We explore the consequences of the latter relationship in the case of a mesoscale model of a block copolymer, and derive the resulting relationship between viscous friction and order parameter diffusion that would result in a lamellar phase. We also explicitly consider in our derivation the fact that the dissipative part of the stress tensor must be consistent with the uniaxial symmetry of the phase. We then obtain a relationship between the stress and order parameter autocorrelation functions that can be interpreted as an extended constitutive law, one that offers a way to determine them from microscopic experiment or numerical simulation.

  20. Techniques for posterior lamellar keratoplasty through a scleral incision

    NARCIS (Netherlands)

    Melles, GRJ; Kamminga, N

    Purpose. To describe several techniques for posterior lamellar keratoplasty through a scleral incision, for management of corneal endothelial disorders like pseudophacic bullous keratopathy and Fuchs' endothelial dystrophy, and to report the mid-term clinical results. Methods. Three techniques have

  1. Structural studies of lamellar surfactant systems under shear

    DEFF Research Database (Denmark)

    Mortensen, K.

    2001-01-01

    Recent experimental studies on concentrated surfactant systems are reviewed. Particular attention is focused on the transformation from planar lamellar sheets to multilamellar vesicles. It is discussed whether both of these states are thermodynamic stable, or if the MLV is an artifact of shear...... induced factors. Recent studies includes the dependence on shear, and dependence on salt and cosurfactants, and thereby related lamellar defects. The review include moreover the demonstration that polymeric amphiphiles dramatically enhance the quality of classical surfactants. (C) 2001 Elsevier Science...

  2. Enzymatic descemetic lamellar keratoplasty: pilot study.

    Science.gov (United States)

    Bonci, Paolo; Bonci, Paola; Della Valle, Vincenzo; Fanini, Francesca; Nardi-Pantoli, Angela

    2010-01-01

    This was a pilot study to evaluate the efficacy of a new surgical technique of descemetic anterior lamellar keratoplasty (DALK) with the help of enzymatic hyaluronidase solution. We selected 10 patients, 6 male and 4 female, with surgical keratoconus, with a mean age of 45+/-16 years (range 29-61), with best-corrected visual acuity (BCVA) Keratron Scout, Optikon 2000, Rome, Italy). The parameters were evaluated monthly, with a maximum follow-up of 8 months. There were no perforations and minimal complications (second anterior chamber in 4 eyes) on the first day, which spontaneously resolved after 7 days. Two patients required resuturing because of loose suture on the second postoperative day. The visual recovery was comparable to that obtained by most authors after DALK. The final mean BCVA was 20/25. There was a drop in endothelial cells of approximately 10.1% after 7 months. The mean central astigmatism at the end of the follow-up was 2 diopters (+/-0.88). The enzyme application to the recipient cornea makes the stromal dissection easier, but other studies are needed about type and concentration of the enzyme, and the application times.

  3. Stabilization of distearoylphosphatidylcholine lamellar phases in propylene glycol using cholesterol.

    Science.gov (United States)

    Harvey, Richard D; Ara, Nargis; Heenan, Richard K; Barlow, David J; Quinn, Peter J; Lawrence, M Jayne

    2013-12-02

    Phospholipid vesicles (liposomes) formed in pharmaceutically acceptable nonaqueous polar solvents such as propylene glycol are of interest in drug delivery because of their ability to improve the bioavailability of drugs with poor aqueous solubility. We have demonstrated a stabilizing effect of cholesterol on lamellar phases formed by dispersion of distearoylphosphatidylcholine (DSPC) in water/propylene glycol (PG) solutions with glycol concentrations ranging from 0 to 100%. The stability of the dispersions was assessed by determining the effect of propylene glycol concentration on structural parameters of the lamellar phases using a complementary combination of X-ray and neutron scattering techniques at 25 °C and in the case of X-ray scattering at 65 °C. Significantly, although stable lamellar phases (and liposomes) were formed in all PG solutions at 25 °C, the association of the glycol with the liposomes' lamellar structures led to the formation of interdigitated phases, which were not thermostable at 65 °C. With the addition of equimolar quantities of cholesterol to the dispersions of DSPC, stable lamellar dispersions (and indeed liposomes) were formed in all propylene glycol solutions at 25 °C, with the significant lateral phase separation of the bilayer components only detectable in propylene glycol concentrations above 60% (w/w). We propose that the stability of lamellar phases of the cholesterol-containing liposomes formed in propylene glycol concentrations of up to 60% (w/w) represent potentially very valuable drug delivery vehicles for a variety of routes of administration.

  4. [Patient satisfaction after posterior lamellar keratoplasty (DSAEK)].

    Science.gov (United States)

    Bachmann, B O; Pogorelov, P; Kruse, F E; Cursiefen, C

    2008-06-01

    The advantages of posterior lamellar keratoplasty (DSAEK) compared to conventional full thickness keratoplasty are faster visual rehabilitation, little change in astigmatism and the absence of suture-associated complications. The current study evaluated the satisfaction of the first 15 patients who underwent DSAEK at our clinic. Evaluation of patient satisfaction was conducted via a telephone survey and by means of a written patient questionnaire. The patients were asked to answer questions on a scale from 1 (very bad) to 10 (very good) about their overall satisfaction with this procedure, their satisfaction with the achieved postoperative visual acuity, their satisfaction with the progress of the healing process and the extent of the perceived burden. The patients were also asked whether they would opt again for the operation. Pre- and postoperative visual acuity, IOP, topographic astigmatism and corneal pachymetry were analysed. 15 eyes of 15 patients were analysed (12 women and 3 men). Average age at the time of operation was 75 +/- 7 years. Visual acuity increased and corneal thickness decreased primarily within the first three months. During that time there was an increase in overall patient satisfaction which finally reached 6.9 +/- 1.8 on the scale. Postoperative visual acuity was awarded with 7.2 +/- 2.0, progress of the healing process with 7.4 +/- 2.3. The procedure was not perceived as a big burden (8.0 +/- 1.9) and most patients would have decided again for the operation (8.2 +/- 2.0). There was no pre- and postoperative difference in IOP and corneal astigmatism. Like in our group patients with diseases of the corneal endothelium are of higher age and therefore benefit from a fast restitution of visual acuity and a low burden of operation. DSAEK represents a secure and practical procedure to rehabilitate elderly patients with diseases of the corneal endothelium.

  5. Lamellar assembly of cadmium selenide nanoclusters into quantum belts.

    Science.gov (United States)

    Liu, Yi-Hsin; Wang, Fudong; Wang, Yuanyuan; Gibbons, Patrick C; Buhro, William E

    2011-10-26

    Here, we elucidate a double-lamellar-template pathway for the formation of CdSe quantum belts. The lamellar templates form initially by dissolution of the CdX(2) precursors in the n-octylamine solvent. Exposure of the precursor templates to selenourea at room temperature ultimately affords (CdSe)(13) nanoclusters entrained within the double-lamellar templates. Upon heating, the nanoclusters are transformed to CdSe quantum belts having widths, lengths, and thicknesses that are predetermined by the dimensions within the templates. This template synthesis is responsible for the excellent optical properties exhibited by the quantum belts. We propose that the templated-growth pathway is responsible for the formation of the various flat, colloidal nanocrystals recently discovered, including nanoribbons, nanoplatelets, nanosheets, and nanodisks.

  6. Deep anterior lamellar keratoplasty: indications, surgical techniques and complications.

    Science.gov (United States)

    Karimian, Farid; Feizi, Sepehr

    2010-01-01

    The concept of lamellar keratoplasty (LK) is not new. However, it had been abandoned and largely replaced by the time-honored technique of penetrating keratoplasty (PK) because LK is technically demanding, time consuming and gives suboptimal visual outcomes due to interface irregularity arising from manual lamellar dissection. Recent improvements in surgical instruments and introduction of new techniques of maximum depth of corneal dissection as well as inherent advantages such as preservation of globe integrity and elimination of endothelial graft rejection have resulted in a re-introduction of LK as an acceptable alternative to conventional PK. This review article describes the indications, different techniques, clinical outcomes and complications of deep anterior LK.

  7. Nanocomposites from block copolymer lamellar nanostructures and selective gold deposition.

    Science.gov (United States)

    Diletto, Claudia; Morvillo, Pasquale; Di Girolamo, Rocco; Auriemma, Finizia; De Rosa, Claudio

    2013-07-01

    Innovative hybrid nanocomposites based on a nanostructured block copolymer (BCP) matrix whose lamellar nanodomains are selectively loaded with metal nanoparticles, have been prepared. A symmetric poly(styrene-b-methylmethacrylate) (PS-b-PMMA) amorphous BCP showing a lamellar morphology has been employed. Thin films of PS-b-PMMA were deposited by spin-coating or drop casting on indium thin oxide (ITO) substrate in order to achieve orientation of lamellae with the lamellar surface perpendicular to the substrate. The perpendicular orientation is related to the use of ITO substrate, which shows a neutral surface with non-preferential interactions with the PS and PMMA domains. Hybrid nanocomposites have been then prepared by selective incorporation of gold nanoparticles into the PS lamellar domain by using a simple method based on the selective deposition of thermally evaporated gold nanoparticles. This innovative approach can be very useful for the realization of nanocomposites that could be used as active layer in non-volatile OFET memory devices or very efficient organic solar cells, depending on the appropriate guest molecules.

  8. Measurements of modulated lamellar Pβ' phases of interacting lipid membranes

    Science.gov (United States)

    Wack, Daniel C.; Webb, Watt W.

    1988-09-01

    A diffraction study of lattice constants in the Pβ' (``rippled'') phase of hydrated lecithins suggests that the lamellar modulation arises from a delicate interplay between the energies associated with membrane curvature and with hydration, as modified by interactions between membranes. Our results imply the existence of a Lifshitz point in the global phase diagram of the lecithin-water system.

  9. Initial results of small incision deep lamellar endothelial keratoplasty (DLEK).

    Science.gov (United States)

    Fogla, Rajesh; Padmanabhan, Prema

    2006-02-01

    To evaluate the results of replacing the posterior stroma and endothelium, using small incision deep lamellar endothelial keratoplasty (DLEK) surgical technique, in patients with corneal endothelial dysfunction. Noncomparative case series. Fifteen eyes of 15 patients (six males and nine females) with endothelial dysfunction were included in this study. Through a 5-mm scleral incision, a deep lamellar pocket was created across the cornea, followed by excision of an 8.0-mm disk of posterior lamellar corneal tissue. Same size lamellar donor disk was prepared and placed in position without the need of suture fixation. Best spectacle-corrected visual acuity (BSCVA), refraction, endothelial cell density, corneal topography, and corneal thickness were analyzed. Average BSCVA preoperative was 20/200 (range 20/40 to hand movements (HM)), improving to 20/50 (range 20/20 to 20/120) at a mean follow-up of 7.2 months. Average refractive astigmatism at last follow-up was 1.46+/-1.21 diopters (range, 0 to 4 diopters). Preoperative average donor endothelial cell density was 2047+/-311 cells/mm2, and that at last follow-up was 1732+/-514 cells/mm2. Preoperative average pachymetry was 801.4+/-211.3 microm, improving to 553+/-90.4 microm at last follow-up. Initial results with small incision DLEK procedure indicate that it is a safe procedure that provides healthy donor endothelial cell count and function postoperatively, with encouraging visual results.

  10. Lamellar-in-lamellar structure of A-b-(B-b-C)(m)-b-B-b-A multiblock copolymers

    NARCIS (Netherlands)

    Subbotin, A.; Klymko, T.; ten Brinke, G.

    2007-01-01

    The number k of "internal" layers for the lamellar self-assembled state of a new class of multiblock copolymers A-b-(B-b-C)(m)-b-B-b-A is determined as a function of m in the strong segregation limit. Here the outer A-blocks are assumed to be considerably longer than the m + 1 blocks of equal length

  11. Can we overcome the challenges of sutures in lamellar keratoplasty?

    Directory of Open Access Journals (Sweden)

    Anita Panda

    2011-01-01

    Full Text Available Lamellar keratoplasty (LK is a technique which can be followed for both tectonic and optical purposes. We describe a technique of sutureless anterior LK by fixing the donor lenticule to the recipient bed using fibrin glue. LK was performed in an eye with corneal opacity using the manual dissection method. The donor lenticule was cut with a microkeratome after fixing the corneoscleral rim in an artificial anterior chamber. The size of the donor lenticule was 8.5 mm and fixed to the recipient bed with fibrin glue. The surgical time was reduced significantly with this technique. There was an uneventful postoperative period during the follow-up of 12 months. Best corrected visual acuity improved from hand movement to 20/60. Thus, the use of fibrin glue for fixing the anterior lamellar lenticule is a viable option for both optical and anatomical purposes.

  12. Quality of corneal lamellar cuts quantified using atomic force microscopy

    Science.gov (United States)

    Ziebarth, Noël M.; Dias, Janice; Hürmeriç, Volkan; Shousha, Mohamed Abou; Yau, Chiyat Ben; Moy, Vincent T.; Culbertson, William; Yoo, Sonia H.

    2012-01-01

    PURPOSE To quantify the cut quality of lamellar dissections made with the femtosecond laser using atomic force microscopy (AFM). SETTING Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA. DESIGN Experimental study. METHODS Experiments were performed on 3 pairs of human cadaver eyes. The cornea was thinned to physiologic levels by placing the globe, cornea side down, in 25% dextran for 24 hours. The eyes were reinflated to normal pressures by injecting a balanced salt solution into the vitreous cavity. The eyes were placed in a holder, the epithelium was removed, and the eyes were cut with a Visumax femtosecond laser. The energy level was 180 nJ for the right eye and 340 nJ for the left eye of each pair. The cut depths were 200 μm, 300 μm, and 400 μm, with the cut depth maintained for both eyes of each pair. A 12.0 mm trephination was then performed. The anterior portion of the lamellar surface was placed in a balanced salt solution and imaged with AFM. As a control, the posterior surface was placed in 2% formalin and imaged with environmental scanning electron microscopy (SEM). Four quantitative parameters (root-mean-square deviation, average deviation, skewness, kurtosis) were calculated from the AFM images. RESULTS From AFM, the 300 μm low-energy cuts were the smoothest. Similar results were seen qualitatively in the environmental SEM images. CONCLUSION Atomic force microscopy provided quantitative information on the quality of lamellar dissections made using a femtosecond laser, which is useful in optimizing patient outcomes in refractive and lamellar keratoplasty surgeries. PMID:23141078

  13. Personalised lamellar keratoplasty and keratopigmentation in Asian corneal leucoma patients

    OpenAIRE

    Liu, Xin; Shen, Jun-Hui; Zhou, Qi; Liu, Zhen-Xing; Tang, Shen-Fei; Chen, Ran-Ran; Sui, Gui-Qin; Bi, Yan-Long

    2015-01-01

    Objective: To describe a personalised lamellar keratoplasty (LK) associated with the keratopigmentation (KTP) technique for corneal leucoma among Asian patients. Methods: This report was a non-randomised, retrospective clinical study performed in 32 consecutive eyes of 32 patients to improve cosmetic appearance. Twenty-two patients underwent LK combined with KTP, either by intralamellar or superficial route. Ten patients underwent the single personalised keratopigmentation method. The subject...

  14. A defect mediated lamellar to isotropic transition of amphiphile bilayers

    OpenAIRE

    Pal, Antara; Pabst, Georg; Raghunathan, V. A.

    2011-01-01

    We report the observation of a novel isotropic phase of amphiphile bilayers in a mixed system consisting of the ionic surfactant, sodium docecylsulphate (SDS), and the organic salt p-toludine hydrochloride (PTHC). This system forms a collapsed lamellar ($L_\\alpha$) phase over a wide range of water content, which transforms into an isotropic phase on heating. This transition is not observed in samples without excess water, where the $L_\\alpha$ phase is stable at higher temperatures. Our observ...

  15. Complications and Management of Deep Anterior Lamellar Keratoplasty

    Directory of Open Access Journals (Sweden)

    Banu Torun Acar

    2014-10-01

    Full Text Available Objectives: To report the intraoperative and postoperative follow-up complications and management of these in deep anterior lamellar keratoplasty (DALK surgery. Materials and Methods: Two hundred eighty-four eyes of 252 patients followed up in our cornea clinic who underwent DALK using Anwar’s big-bubble technique with healthy Descemet’s membrane and endothelium were included in this study. Intraoperative and postoperative complications as well as the management and treatment of these complications were evaluated. Results: Big bubble was created in 220 (77.5% eyes of 284 eyes, and lamellar dissection was performed in 64 (22.5% eyes. Perforation occurred during trephination in 4 eyes, and the procedure was accomplished by penetrating keratoplasty (PK. Intraoperative microperforation occurred in 44 eyes. Perforation enlarged in 4 eyes and PK was performed. Operation was continued in 40 eyes with air injection into the anterior chamber. In postopertive follow-up period, double anterior chamber (DAC occurred in 32 of 40 eyes. DAC spontaneously regressed in 8 eyes, and air was given into the anterior chamber with a second surgical intervention in 24 eyes. DAC improved in 20 eyes. Four eyes underwent PK. Fungal keratitis evolved at the interface in one eye, because of no healing during the follow-up period, this eye underwent PK under antifungal therapy. Eyes with interface haze and Descemet’s membrane folds were followed. Conclusion: DALK is a difficult technique with a steep learning curve. In addition to the complications seen in PK, specific complications can occur in lamellar surgery. (Turk J Ophthalmol 2014; 44: 337-40

  16. [Techniques for posterior lamellar keratoplasty through a scleral incision].

    Science.gov (United States)

    Melles, G R J; Kamminga, N

    2003-09-01

    To describe several techniques for posterior lamellar keratoplasty through a scleral incision, for management of corneal endothelial disorders like pseudophacic bullous keratopathy and Fuchs' endothelial dystrophy, and to report the mid-term clinical results. Three techniques have been developed to perform a posterior lamellar keratoplasty procedure through a scleral incision, i.e. to replace the posterior corneal layers while leaving the anterior corneal surface intact and without the use of corneal sutures. In the first technique, a 9.0 mm scleral incision is made to accommodate an intracorneal trephine and spoon-shaped glide to insert a 7.5 mm donor posterior lamellar disc into the anterior chamber. In the second technique, the procedure is performed through a 5.0 mm scleral tunnel incision using microscissors and by folding a 8.5 mm donor posterior disc prior to insertion. In the third technique, a 4.0 mm tunnel incision is made to perform a descemetorhexis in the host cornea, i.e. Descemet's membrane is selectively excised from the recipient eye, and a 9.0 mm donor Descemet's membrane is inserted. In eyes with a minimal postoperative follow-up of 3-5 years ( n=16), we documented the best spectacle corrected visual acuity (BSCVA), keratometry readings, endothelial cell counts, and clinical events. In all cases, the graft adhered to the recipient posterior cornea without suture fixation. In patients without concomitant ocular disease, BSCVA was 0.7-1.0 in all eyes. The astigmatism averaged 2.1+/-0.7 D, endothelial cell counts averaged 2126+/-529 cells/mm(2) at 6 months, 1839+/-473 cells/mm(2) at 12 months, 1418+/-434 cells/mm(2) at 24 months, and 1137+/-420 cells/mm(2) at 36 months. In two patients, an irido-corneal adhesiolysis was performed within days after the procedure. In one patient, residual visco-elastic adherence was present at the donor-to-recipient interface, and a penetrating keratoplasty was performed 1 month postoperation. One patient developed

  17. Synthesis and characterization of lamellar aragonite with hydrophobic property

    Energy Technology Data Exchange (ETDEWEB)

    Wang Chengyu, E-mail: wangcy@nefu.edu.cn [College of Materials Science and Engineering, Northeast Forestry University, 150040 (China); Xu Yang [China Nation Center for Quality Supervision and Test of Woodworking Machinery, Northeast Forestry University, 150040 (China); Liu Yalan; Li Jian [College of Materials Science and Engineering, Northeast Forestry University, 150040 (China)

    2009-04-30

    A novel and simple synthetic method for the preparation of hydrophobic lamellar aragonite has been developed. The crystallization of aragonite was conducted by the reaction of sodium carbonate with calcium chloride in the presence of sodium stearate. The resulting products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and the contact angle. The results revealed that sodium stearate plays an important role in determining the structure and morphology of the sample. Besides, we have succeeded in surface modification of particles in situ at the same time. The contact angle of the modified aragonite reached 108.59 deg.

  18. Precipitation of lamellar gold nanocrystals in molten polymers

    Energy Technology Data Exchange (ETDEWEB)

    Palomba, M.; Carotenuto, G., E-mail: giancaro@unina.it [Institute for Polymer, Composites, and Biomaterials. National Research Council. Piazzale E. Fermi, 1 – 80055 Portici (Italy)

    2016-05-18

    Non-aggregated lamellar gold crystals with regular shape (triangles, squares, pentagons, etc.) have been produced by thermal decomposition of gold chloride (AuCl) molecules in molten amorphous polymers (polystyrene and poly(methyl methacrylate)). Such covalent inorganic gold salt is high soluble into non-polar polymers and it thermally decomposes at temperatures compatible with the polymer thermal stability, producing gold atoms and chlorine radicals. At the end of the gold precipitation process, the polymer matrix resulted chemically modified because of the partial cross-linking process due to the gold atom formation reaction.

  19. Tectonic Lamellar Keratoplasty Using Cryopreserved Cornea in a Large Descemetocele.

    Science.gov (United States)

    Kim, Kang Yoon; Jung, Ji Won; Kim, Eung Kweon; Seo, Kyoung Yul; Kim, Tae Im

    2016-01-01

    We describe herein a case of an impending corneal perforation with a large descemetocele in a patient with previous penetrating keratoplasty (PKP) that subsequently was treated with an emergent lamellar keratoplasty using frozen preserved cornea. A 76-year-old male patient, who had a PKP, presented with a completely whitish and edematous graft accompanied by large epithelial defects. Although antibiotics and antiviral agents were tried for three days, the corneal stroma abruptly melted, except for the Descemet's membrane and endothelium. Cryopreserved corneal tissue that was kept at -80°C was thawed and sutured on top of the remaining Descemet's membrane and endothelium. Pathological and microbiological tests were conducted using the remaining donor and recipient corneal tissues. After tectonic corneal transplantation on top of a large descemetocele, a healthy graft and relatively clear interfaces between graft-host junctions were maintained without serious adverse reactions throughout 6 month follow-up period. Microbiological evaluations of donor tissue at the time of thawing and tissue preparation were done, and the results were all negative. Tissue that was taken intraoperatively from the recipient cornea also showed negative microbiological results. In conclusion, tectonic lamellar keratoplasty, using cryopreserved corneal tissue, only onto the remaining Descemet's membrane and endothelium in an emergent condition, was a safe and effective treatment.

  20. Deep anterior lamellar keratoplasty using an original manual technique.

    Science.gov (United States)

    Rama, Paolo; Knutsson, Karl Anders; Razzoli, Giulia; Matuska, Stanislav; Viganò, Maurizia; Paganoni, Giorgio

    2013-01-01

    To evaluate the clinical findings and visual outcomes of deep anterior lamellar keratoplasty (DALK) using an original manual dissection technique. 288 eyes (268 patients) with corneal pathologies without endothelial involvement were treated by DALK using an original manual dissection technique guided by a calibrated knife incision based on ultrasonic pachimetry values. Clinical records were examined retrospectively at 2 months, 6 months, 1 year and 2 years. The following outcomes were measured: visual acuity, topographic parameters, endothelial cell density and recipient stromal residue thickness. At the 2-year postoperative follow-up, the mean logarithm of the minimum angle of resolution best spectacle corrected visual acuity (BSCVA) was 0.131±0.087 and topographic astigmatism was 2.87±1.57 diopters. In 12 cases (4.2%) a perforation of Descemet's membrane required conversion of the procedure to penetrating keratoplasty. Mean optical coherence tomography (OCT) residue thickness (measured in 82 eyes with OCT Visante) was 31.63±24.57 μm; lower values of recipient residue thickness were significantly associated with higher BSCVA (Spearman coefficient 0.635, p< 0.001). DALK using a dry manual dissection technique provides visual, refractive and clinical results comparable to other deep lamellar techniques. Eyes with lower values of recipient residue thickness are associated with better visual acuity.

  1. Impact of ventilation-induced lung injury on the structure and function of lamellar bodies.

    Science.gov (United States)

    Milos, Scott; Khazaee, Reza; McCaig, Lynda A; Nygard, Karen; Gardiner, Richard B; Zuo, Yi Y; Yamashita, Cory; Veldhuizen, Ruud

    2017-09-01

    Alterations to the pulmonary surfactant system have been observed consistently in ventilation-induced lung injury (VILI) including composition changes and impairments in the surface tension reducing ability of the isolated extracellular surfactant. However, there is limited information about the effects of VILI on the intracellular form of surfactant, the lamellar body. It is hypothesized that VILI leads to alterations of lamellar body numbers and function. To test this hypothesis, rats were randomized to one of three groups, nonventilated controls, control ventilation, and high tidal volume ventilation (VILI). Following physiological assessment to confirm lung injury, isolated lamellar bodies were tested for surfactant function on a constrained sessile drop surfactometer. A separate cohort of animals was used to fix the lungs followed by examination of lamellar body numbers and morphology using transmission electron microscopy. The results showed an impaired ability of reducing surface tension for the lamellar bodies isolated from the VILI group as compared with the two other groups. The morphological assessment revealed that the number, and the relative area covered by, lamellar bodies were significantly decreased in animals with VILI animals as compared with the other groups. It is concluded that VILI causes significant alterations to lamellar bodies. It is speculated that increased secretion causes a depletion of lamellar bodies that cannot be compensated by de novo synthesis of surfactant in these injured lungs. Copyright © 2017 the American Physiological Society.

  2. Equation of state of a charged bilayer system: Measure of the entropy of the lamellar-lamellar transition in DDABr

    Science.gov (United States)

    Dubois, M.; Zemb, Th.; Fuller, N.; Rand, R. P.; Parsegian, V. A.

    1998-05-01

    The synthetic cationic double-chain surfactant didodecyldimethylammonium bromide shows two distinct thermodynamically stable lamellar phases; a dilute Lα phase stabilized predominantly by electrostatic forces, and a condensed Lα' phase stabilized by "hydration" forces. Using six different experimental methods, applying osmotic stress from 102 to 109Pa and varying temperature from 20 °C to 70 °C, we have measured the osmotic pressure vs interbilayer distance and thus mapped the phase diagram with an equation of state. In this binary system, the area per headgroup as well as bilayer thickness vary with concentration and temperature. Hence, lateral compressibility has to be taken into account in the free energy balance. The osmotic stress needed to effect the swollen-to-collapsed lamellar phase transition is determined as a function of temperature. From these data the entropy of the Lα-Lα' transition is found to be a strong function of temperature. Below 40 °C, condensation from the dilute Lα phase, the change of entropy is negative as might be expected. Above 40 °C the entropy of condensation is positive, demonstrating that there is a release of degrees of freedom associated with the bilayer condensation. These data allow us to think far more critically about the forces that stabilize bilayer systems.

  3. Steric-induced effects on stabilizing a lamellar structure.

    Science.gov (United States)

    Gerbelli, Barbara B; Rubim, Rafael L; Silva, Emerson R; Nallet, Frédéric; Navailles, Laurence; Oliveira, Cristiano L P; de Oliveira, Elisabeth A

    2013-11-12

    We investigate the behavior of multilamellar phases composed of lecithin and a commercial cosurfactant (Simusol), which is a mixture of ethoxylated fatty acids. Using X-ray scattering and a new procedure to fit the data, relevant parameters characterizing the lamellar structure were determined as a function of membrane composition, varying from 100% of lecithin to 100% of Simulsol. Scattering data illustrating the swelling of the lamellae for different amounts of cosurfactant are presented with the respective behavior of the Caillé parameter. With this experimental approach, we show that the incorporation of ethoxy brushes onto the lipid surface enhances repulsive interactions arising from membrane fluctuations and changes the interactions at the interface between bilayers.

  4. Novel spatula and dissector for safer deep anterior lamellar keratoplasty

    Directory of Open Access Journals (Sweden)

    Gustavo ,2,3 Bonfadini

    2014-10-01

    Full Text Available Objective: We describe a novel spatula and dissector to facilitate the big-bubble technique in deep anterior lamellar keratoplasty (DALK. Methods: A 29-year-old man who was diagnosed with bilateral keratoconus underwent deep anterior lamellar keratoplasty (DALK. After 350μm partial thickness incision of the recipient cornea, the Bonfadini dissector was inserted at the deepest point in the peripheral incision and could be advanced to the center of the cornea safely because of its "semi-sharp" tip. After achieving the big-bubble (BB separation of Descemet membrane (DM from the overlying stroma, the anterior stromal disc was removed. Viscoelastic material was placed on the stromal bed to prevent uncontrolled collapse and perforation of DM during the paracentesis blade incision into the BB. We could detect the safe opening of the BB using the Bonfadini dissector by the leakage of air bubbles into the viscoelastic material. After injecting viscoelastic material into the BB space, we inserted the Bonfadini spatula into the bigbubble safely because of its curved profile and blunt edges. The groove along the length of the Bonfadini spatula enables safe and efficient incision or the residual stromal tissue using the pointed end of a sharp blade while protecting the underlying DM. After removal of posterior stroma, the donor button was sutured with 16 interrupted 10-0 nylon sutures. Results: This technique and the use of the Bonfadini spatula and dissector facilitate exposure of Descemet membrane. Conclusion: The smooth Bonfadini DALK spatula and dissector facilitate safe and efficient completion of DALK surgery.

  5. [Applying deep lamellar keratoplasty in corneal disorders without endothelial abnormalities].

    Science.gov (United States)

    Wylegała, Edward; Wróblewska, Ewa Marta; Tarnawska, Dorota; Mierzwa, Marzena

    2003-01-01

    To present own experiences in the surgery of deep lamellar keratoplasty. 25 eye of 25 patients suffering from various corneal pathologies with preserved endothelium: 22 with keratoconus eyes, 2 with post-inflammatory scar and one eye with leucoma in Stevens-Johnson syndrome. Mean follow-up was 25.5 months (from 6 to 32). Main outcome measures were Non-Corrected and Best Corrected Visual Acuity (NCVA, BCVA), astigmatism, refractive error, IOP and corneal transparency. The surgery was performed in general anesthesia. In majority of cases the recipient stroma was trephined to a depth of 70% with 7.5 mm diameter vacuum trephine. In cases of intraoperative perforation of Descemet membrane with shallow anterior chamber we converted the procedure into penetrating keratoplasty. The donor lenticule was trephined in the artificial chamber with the 0.5 mm oversized manual trephine to a depth of 90%. In two cases after DLK was finished, limbal stem cell grafting was additionally performed. Postoperative NCVA ranged from 0.01 to 0.8 and BCVA from 0.1 to 0.8. Astigmatism ranged from 0.5 to 10.0 D. Refractive error ranged from -8.0 to +1.0 D. In follow-up period all grafts maintained transparent. The complications were mainly intraoperative perforations of Descemet membrane (9 cases): in 7 cases we convert the procedure into penetrating keratoplasty. In 2 cases the double chamber-forming was observed: in one case on 7 day following surgery the penetrating keratoplasty was performed, in other a spontaneous attachment was observed. We also observed loose sutures in 2 cases, inflammatory infiltrates in one case. Two cases of ocular hypertension was successfully treated by medication. Deep lamellar keratoplasty is an effective procedure for treating various diseases of corneal stroma with unaffected endothelium.

  6. Femtosecond laser-assisted lamellar keratoplasty: early results.

    Science.gov (United States)

    Mosca, Luigi; Fasciani, Romina; Tamburelli, Ciro; Buzzonetti, Luca; Guccione, Laura; Mandarà, Erika; Balestrazzi, Emilio

    2008-07-01

    To evaluate the outcomes and safety of lamellar keratoplasty (LK) assisted by a femtosecond laser. Twenty-one eyes of 21 patients affected by different corneal pathologies (5 posttraumatic corneal scar, 3 postkeratitis corneal leucoma, and 13 keratoconus) underwent LK procedures by using a femtosecond laser. The mean thinnest corneal thickness, evaluated with ultrasound corneal pachymetry and with confocal microscopy, was 434.19 +/- 62.60 (SD) microm (range, 333-548 microm). Mean preoperative uncorrected visual acuity was 0.09 +/- 0.28 SD and mean preoperative best spectacle-corrected visual acuity was 0.28 +/- 0.15 SD. A femtosecond laser was used to perform corneal cuts on both donor and recipient corneas. The donor corneal lamella diameters were 0.20-mm larger and thicker than the recipient to restore a physiologic corneal thickness and shape: mean donor diameter was 8.34 +/- 0.28 mm (range, 8.2-8.7 mm) and mean thickness was 352 +/- 40.27 microm (range, 220-400 microm). Mean follow-up was 20.86 +/- 5.76 months (range, 12-30 months). Early postoperative evaluation showed a clear graft in all cases. A normal corneal pattern topography and a physiologic thickness (mean corneal pachymetry, 542.48 +/- 33.20 microm) and transparency were restored. Twelve months after surgery, the mean postoperative uncorrected visual acuity was 0.45 +/- 0.34 SD, and the mean best spectacle-corrected visual acuity was 0.63 +/- 0.16 SD. Although the numbers in our study are small, our early results indicate that femtosecond laser-assisted lamellar keratoplasty shows promise as a safe and effective surgical choice in the treatment of various corneal pathologies.

  7. Lamellar body ultrastructure revisited: high-pressure freezing and cryo-electron microscopy of vitreous sections.

    Science.gov (United States)

    Vanhecke, Dimitri; Herrmann, Gudrun; Graber, Werner; Hillmann-Marti, Therese; Mühlfeld, Christian; Studer, Daniel; Ochs, Matthias

    2010-10-01

    Lamellar bodies are the storage sites for lung surfactant within type II alveolar epithelial cells. The structure-function models of lamellar bodies are based on microscopic analyses of chemically fixed tissue. Despite available alternative fixation methods that are less prone to artifacts, such as cryofixation by high-pressure freezing, the nature of the lung, being mostly air filled, makes it difficult to take advantage of these improved methods. In this paper, we propose a new approach and show for the first time the ultrastructure of intracellular lamellar bodies based on cryo-electron microscopy of vitreous sections in the range of nanometer resolution. Thus, unspoiled by chemical fixation, dehydration and contrasting agents, a close to native structure is revealed. Our approach uses perfluorocarbon to substitute the air in the alveoli. Lung tissue was subsequently high-pressure frozen, cryosectioned and observed in a cryo-electron microscope. The lamellar bodies clearly show a tight lamellar morphology. The periodicity of these lamellae was 7.3 nm. Lamellar bifurcations were observed in our cryosections. The technical approach described in this paper allows the examination of the native cellular ultrastructure of the surfactant system under near in vivo conditions, and therefore opens up prospectives for scrutinizing various theories of lamellar body biogenesis, exocytosis and recycling.

  8. Rab11a Is Essential for Lamellar Body Biogenesis in the Human Epidermis.

    Science.gov (United States)

    Reynier, Marie; Allart, Sophie; Gaspard, Elise; Moga, Alain; Goudounèche, Dominique; Serre, Guy; Simon, Michel; Leprince, Corinne

    2016-06-01

    Most of the skin barrier function is attributable to the outermost layer of the epidermis, the stratum corneum, which is composed of flattened, anucleated cells called corneocytes surrounded by a lipid-enriched lamellar matrix. The composition of the stratum corneum is directly dependent on the underlying granular keratinocytes, which are the last living cells in the stratified epidermis. Many components present in the intercorneocyte matrix are delivered by the underlying granular keratinocytes through a secretion process dependent on lysosome-related organelles called lamellar bodies. Because of the importance of lamellar bodies in the maintenance of the epidermal barrier, the mechanisms regulating their biogenesis must be better understood. In this study, we show that the Rab11a GTPase is highly expressed in terminally differentiated keratinocytes, where it is partly associated with lamellar bodies. Rab11a silencing in three-dimensional in vitro reconstructed human epidermis induces a barrier defect, a decrease in the amount of lipid found in the stratum corneum, a reduction in lamellar body density and secretion areas in granular keratinocytes, and the mis-sorting of lamellar body cargoes being driven to the lysosomal degradation pathway. Our results highlight the importance of Rab11a-dependent regulation of lamellar body biogenesis in keratinocytes and consequently on epidermal barrier homeostasis. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  9. Economic evaluation of deep anterior lamellar keratoplasty versus penetrating keratoplasty in The Netherlands

    NARCIS (Netherlands)

    Biggelaar, F.J. van den; Cheng, Y.Y.; Nuijts, R.M.; Schouten, J.S.A.G.; Wijdh, R.J.; Pels, E.; Cleynenbreugel, H. van; Eggink, C.A.; Zaal, M.J.; Rijneveld, W.J.; Dirksen, C.D.

    2011-01-01

    PURPOSE: To evaluate the cost effectiveness of deep anterior lamellar keratoplasty (DALK) versus penetrating keratoplasty (PK) in The Netherlands. DESIGN: Cost-effectiveness analysis alongside a randomized, multicenter clinical trial. METHODS: Fifty-three patients with corneal stromal pathologic

  10. Economic Evaluation of Deep Anterior Lamellar Keratoplasty Versus Penetrating Keratoplasty in The Netherlands

    NARCIS (Netherlands)

    van den Biggelaar, Frank J. H. M.; Cheng, Yanny Y. Y.; Nuijts, Rudy M. M. A.; Schouten, Jan S.; Wijdh, Robert-Jan; Pels, Elisabeth; van Cleynenbreugel, Hugo; Eggink, Catharina A.; Zaal, Michel J. W.; Rijneveld, Wilhelmina J.; Dirksen, Carmen D.

    PURPOSE: To evaluate the cost effectiveness of deep anterior lamellar keratoplasty (DALK) versus penetrating keratoplasty (PK) in The Netherlands. DESIGN: Cost-effectiveness analysis alongside a randomized, multicenter clinical trial. METHODS: Fifty-three patients with corneal stromal pathologic

  11. Parallel and perpendicular lamellar phases in copolymer-nanoparticle multilayer structures

    Energy Technology Data Exchange (ETDEWEB)

    Lauter-Pasyuk, V.; Lauter, H.; Gordeev, G.; Mueller-Buschbaum, P.; Toperverg, B.P.; Petry, W.; Jernenkov, M.; Petrenko, A.; Aksenov, V

    2004-07-15

    Recent results in developing novel nanocomposite multilayer structures are presented. We used symmetric polystryrene-block-polymethylmethacrylate (deuterated) P(S-b-MMAd) lamellar thin films as a self-assembling matrix for the lamellar arrangement of Fe{sub 3}O{sub 4} nanoparticles. Pure copolymer films showed an unusual structure with a perpendicular to the surface orientation of the lamellae, in the part of the film towards the free surface. This is a new phenomenon because up to now this orientation was obtained only on specially prepared substrates. After the incorporation of nanoparticles into the copolymer matrix, the system switched to a lamellar structure parallel to the surface. Further increasing of the nanoparticles concentration led to a more perfect lamellar structure, which shows that the limit for a high concentration of nanoparticles, important for nanotechnology has not yet been reached.

  12. Micro alloyed steel weldability and sensibility testing on the lamellar cracks appearance

    Directory of Open Access Journals (Sweden)

    S. Stojadinović

    2011-07-01

    Full Text Available In this work are given the testing results of mechanical properties welded joints and microstructure of micro alloyed steel as well as its sensitivity to lamellar cracks appearance. The obtained results show that steel has good resistance to lamellar cracks appearance and with an appropriate wire choice for welding, a good combination of mechanical properties could be obtained at room (ambience temperatures as well as at low temperatures.

  13. AMNIOTIC FLUID LAMELLAR BODY COUNT FOR PREDICTION OF FOETAL LUNG MATURITY

    Directory of Open Access Journals (Sweden)

    Aruna Ratikrinda

    2016-06-01

    Full Text Available INTRODUCTION Predicting maturity of the foetal lung is extremely important in many obstetric situations as respiratory distress syndrome caused by surfactant deficiency remains one of the leading causes of neonatal morbidity and mortality. The need for predicting the foetal lung maturity by means of an accurate test which is done rapidly and available in majority of centres was the objective for this study. AIM To find out the optimum lamellar body count which correlates with foetal lung maturity and to compare the lamellar body count with shake bubble test. MATERIAL AND METHODS This prospective study was designed to evaluate the lamellar body count by standard haematology cell counter that is coulter counter and compare it with shake bubble test. Both the tests were done on 100 amniotic fluid samples in women with gestational age more than 28 weeks. Patients recruited were those who were sure of their last menstrual period (LMP, who were in active labour, and likely to deliver within 72 hours of collection of sample. Amniotic fluid samples obtained by transabdominal amniocentesis or by aspirating the forewaters per vaginum. Both shake bubble test and lamellar body count were done on the sample. RESULTS Lamellar body counts ranged from 10,000-2,43,000/microlitre and had a linear relationship with gestational age. The cut-off level of 30,000/microlitre was considered to be optimum to predict foetal lung maturity. Sensitivity and negative predictive value of lamellar body count at 30,000/microlitre and shake bubble test were comparable at 91.7%/91.7% and 97.3/96.6% respectively whereas with respect to specificity and positive predictive value, lamellar body count was superior to shake bubble test at 93.4%/73.7% and 81.5%/50%. CONCLUSION Lamellar body count is a rapid, inexpensive, simple and more reliable test to assess foetal lung maturity

  14. Comparative Proteomic Analysis of Lung Lamellar Bodies and Lysosome-Related Organelles

    OpenAIRE

    Ross Ridsdale; Cheng-Lun Na; Yan Xu; Greis, Kenneth D; Timothy Weaver

    2011-01-01

    Pulmonary surfactant is a complex mixture of lipids and proteins that is essential for postnatal function. Surfactant is synthesized in alveolar type II cells and stored as multi-bilayer membranes in a specialized secretory lysosome-related organelle (LRO), known as the lamellar body (LB), prior to secretion into the alveolar airspaces. Few LB proteins have been identified and the mechanisms regulating formation and trafficking of this organelle are poorly understood. Lamellar bodies were iso...

  15. A finite element model for ultrafast laser-lamellar keratoplasty.

    Science.gov (United States)

    Fernández, D Cabrera; Niazy, A M; Kurtz, R M; Djotyan, G P; Juhasz, T

    2006-01-01

    A biomechanical model of the human cornea is employed in a finite element formulation for simulating the effects of Ultrafast Laser-Lamellar Keratoplasty. Several computer simulations were conducted to study curvature changes of the central corneal zone under various physiological and surgical factors. These factors included the combined effect of corneal flap and residual stromal bed thickness on corneal curvature; the effect of the shape of the lenticle on the surgical procedure outcomes and the effect of flap thickness on stress distribution in the cornea. The results were validated by comparing computed refractive power changes with clinical results. The effect of flap thickness on the amount of central flattening indicates that for flap thickness values 28% over the corneal thickness, central corneal flattening decreases. Moreover, the change in corneal curvature induced by subtraction of a plano-convex lenticle under a uniform flap, naturally imply a smaller change in the structure of the anterior layers of the cornea, but a bigger deformation in the structure of the posterior layers that are left behind the resection of the lenticle. In addition, the model also verified that the corneal curvature increased peripherally with simultaneous thinning centrally after subtraction of corneal tissue. This result shows that not only the treated zone is affected by the surgery, indicating the important role of the biomechanical response of the corneal tissue to refractive surgery, which is unaccounted for in current ablation algorithms. The results illustrate the potentialities of finite element modeling as an aid to the surgeon in evaluating variables.

  16. Butterfly patterns in a sheared lamellar-system

    Energy Technology Data Exchange (ETDEWEB)

    Lindner, P. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France); Zipfel, J.; Richtering, W. [Freiburg Univ. (Germany)

    1997-04-01

    A technologically important extension of `classical` scattering techniques is to investigate soft-matter systems under non-equilibrium conditions. Shear flow is known to have a profound influence on the structure and orientation of complex fluids like thermotropic or lyotropic liquid-crystals, colloidal and polymeric solutions. There is a fundamental interest in understanding the microscopic structure and dynamics of such complex fluids as the macroscopic material properties might change with the application of an external perturbation like shear. The following example illustrates a recent study of the influence of shear on the structure of a lyotropic lamellar phase. Results using a cone-and-plate and the ILL Couette type shear-cell were obtained by rheo-small-angle light scattering (rheo-SALS) and small-angle neutron scattering (SANS) at D11. Because of the broad range of momentum transfer Q available at D11 a characteristic butterfly-pattern with a scattering peak revealing both the structure and the supramolecular structure of the system could be detected at very low Q. (author). 5 refs.

  17. Femtosecond laser-assisted decagonal deep anterior lamellar keratoplasty.

    Science.gov (United States)

    Espandar, Ladan; Mandell, Jonathan B; Niknam, Sasan

    2016-04-01

    To assess the use of a new polygonal trephination pattern for deep anterior lamellar keratoplasty (DALK) assisted by femtosecond laser. Prospective, nonrandomized clinical study. Twenty-four eyes underwent decagonal DALK. All except 1 had advanced keratoconus. A laser was used to create decagonal cuts on both donor and recipient corneas. All patients were assessed for uncorrected visual acuity, best spectacle-corrected visual acuity (BCVA), and keratometry by Pentacam pre- and postoperatively. All eyes were treated successfully without intraoperative complications. All patients were followed for 18 months. Mean ± SD of postoperative BCVA was 0.26 ± 0.16 (logarithm of minimal angle of resolution), and there was a significant improvement in BCVA after 6 months. At 18 months, mean ± SD postoperative average K was 44.48 ± 0.87 D, which was significantly lower than preoperative average K (58.42 ± 12.1). Postoperative astigmatism at 18 months (mean ± SD: 1.82 ± 0.67) was significantly lower than that at 6 months (mean ± SD: 3.27 ± 0.81) (p = 0.001). Use of the decagonal trephination profile was effective to perform DALK. This study showed promising visual and refractive results. Longer follow-up, larger pool of patients, and comparative studies are necessary to determine advantages and optimal surgical settings of this technique. Copyright © 2016 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.

  18. Small Incision Lenticule Extraction After Deep Anterior Lamellar Keratoplasty.

    Science.gov (United States)

    Mastropasqua, Leonardo; Calienno, Roberta; Lanzini, Manuela; Nubile, Mario

    2015-09-01

    Femtosecond laser-assisted small incision lenticule extraction (SMILE) was performed to correct myopic astigmatism in a 39-year-old patient who had previously undergone deep anterior lamellar keratoplasty (DALK) for keratoconus, with clinically significant anisometropia and contact lens intolerance. Case report. SMILE was planned in the right eye to reduce the refractive error and to allow spectacle correction. The surgical procedure was centered on the visual axis, a 5.20-mm optical zone was used, and the refractive lenticule was extracted through a 3.25-mm incision located inside the graft edge. The refractive target was achieved 1 week after surgery and remained stable until the 3-month follow-up visit, while the corrected distance visual acuity improved from 20/100 to 20/40. Complications were not observed and the graft remained clear. In vivo confocal microscopy and anterior segment optical coherence tomography highlighted a regular wound healing and refractive interface profile. This case report highlights the feasibility of using SMILE as an alternative procedure for correcting refractive errors after keratoplasty, but further prospective studies are needed to prove the long-term refractive outcomes and safety of this technique. Copyright 2015, SLACK Incorporated.

  19. [Clinical results of femtosecond laser assisted lamellar keratoplasty].

    Science.gov (United States)

    Li, Shaowei; Ning, Jianhua; Liu, Chang; Guo, Zuofeng; Lyn, Fangqi; Chen, Tiehong

    2015-06-01

    To report the clinical results of femtosecond laser assisted lamellar keratoplasty (FS-LK). Retrospective study. Twenty eyes of 17 patients who were treated with FS-LK were enrolled in this study. The preoperative visions were from 0.02 to 0.4. During the operation, the grafts were prepared with a depth of 400-600 µm according to the character of the affections. During the follow-up period, the visions of 18 eyes (90%) were better than preoperative ones. One of them was equal to 0.8. The best corrected visual acuities of 18 eyes (90%) were better than or equal to 0.5, one of which was 1.0. The astigmatisms of 15 eyes were under 3.00 diopters at one year after operation. During the operation of two cases, the paracentral cut occurred. Two patients experienced corneal opacity, and two cases had high astigmatisms after operation. Only one eye experienced immune rejection at one year after operation. The FS-LK appears to be a good alternative surgical method for patients with corneal diseases because of the great manipuility and excellent postoperative results, but more research is needed.

  20. Personalised lamellar keratoplasty and keratopigmentation in Asian corneal leucoma patients.

    Science.gov (United States)

    Liu, Xin; Shen, Jun-Hui; Zhou, Qi; Liu, Zhen-Xing; Tang, Shen-Fei; Chen, Ran-Ran; Sui, Gui-Qin; Bi, Yan-Long

    2015-01-01

    To describe a personalised lamellar keratoplasty (LK) associated with the keratopigmentation (KTP) technique for corneal leucoma among Asian patients. This report was a non-randomised, retrospective clinical study performed in 32 consecutive eyes of 32 patients to improve cosmetic appearance. Twenty-two patients underwent LK combined with KTP, either by intralamellar or superficial route. Ten patients underwent the single personalised keratopigmentation method. The subjective and objective cosmetic results, ocular irritation, colour fading, neovascularisation formation and incidence of immune rejection were evaluated until three years after surgery. No complications occurred, and the corneal leucoma was successfully stained with India ink in all 32 patients. Most of the patients showed good cosmetic appearance. Pain, conjunctival congestion, corneal edema and foreign body sensation disappeared gradually within two to three weeks after surgery in all patients. Graft swelling, non-healing, or detaching was not observed during follow-up. However, two patients had slight opacity three years after LK. Colour fading was observed in one patient who underwent intralamellar corneal staining 10 months after surgery. Re-staining was performed. KTP combined with personalised LK is an effective personalised technique that presents long-standing colour staining and good cosmetic efficacy.

  1. Lamellar Diffuse Keratitis. Its management and clinical evolution.

    Directory of Open Access Journals (Sweden)

    Jenny García Milián

    2009-12-01

    Full Text Available The new advances in Refractive Surgery have led to an increment in the indications of the LASIK, but also of their complications. Among the postoperative complications, Diffuse Lamellar Keratitis (DLK can occur with a frequency of approximately between 1.8% and 12% of the cases. The objective of this work is to describe the behavior of DLK in patients intervened by the LASIK technique and its clinical evolution. A retrospective cross-sectional descriptive study was made of 5 cases of DLK observed in 253 patients (eyes operated by Lasik in the Ophthalmological Center of Sancti Spíritus between April 3 2008 and April 9 2009. The studied variables were: associated risk factors, beginning of clinical assessment in days, reached stage, type of treatment, duration and time of follow-up and visual results. In the 5 studied cases an average beginning of clinical assessment was observed at 3 days with blurred vision and slight ocular troubles, all were treated with steroidal antinflamatory drugs topically administered obtaining a mean AVC/SC preQX =0, 98 AV mean last control =0, 94, and a average duration of treatment of 15 days, with stages I and II being the ones that prevailed in the sample. It has been shown that DLQ is a complication that can be innocuous for visual results after the application of LASIK, if it is treated appropriately and in an early way.

  2. Nanoscale lamellar photoconductor hybrids and methods of making same

    Science.gov (United States)

    Stupp, Samuel I; Goldberger, Josh; Sofos, Marina

    2013-02-05

    An article of manufacture and methods of making same. In one embodiment, the article of manufacture has a plurality of zinc oxide layers substantially in parallel, wherein each zinc oxide layer has a thickness d.sub.1, and a plurality of organic molecule layers substantially in parallel, wherein each organic molecule layer has a thickness d.sub.2 and a plurality of molecules with a functional group that is bindable to zinc ions, wherein for every pair of neighboring zinc oxide layers, one of the plurality of organic molecule layers is positioned in between the pair of neighboring zinc oxide layers to allow the functional groups of the plurality of organic molecules to bind to zinc ions in the neighboring zinc oxide layers to form a lamellar hybrid structure with a geometric periodicity d.sub.1+d.sub.2, and wherein d.sub.1 and d.sub.2 satisfy the relationship of d.sub.1.ltoreq.d.sub.2.ltoreq.3d.sub.1.

  3. Lamellar ichthyosis maps to chromosome 14q11

    Energy Technology Data Exchange (ETDEWEB)

    Russell, L.J.; Compton, J.G.; Bale, S.J. [and others

    1994-09-01

    Lamellar ichthyosis (LI) is a serious skin disorder inherited as an autosomal recessive trait and characterized by large, brown plate-like scales covering the body. Skin involvement is apparent at birth, often as a collodion membrane. Scarring alopecia, ectropion, and secondary hypohidrosis are frequent. We used a panel of candidates genes that are expressed in the epidermis to study seven multiplex Caucasian families in the U.S. and six inbred (multiplex and simplex) families in Egypt. We find no recombination (Z=9.11 at {theta}=0) in either set of families with transglutaminse 1 (TGM1), the gene encoding the enzyme responsible for cross-linking proteins to the cell envelope in the upper-most layer of the epidermis. In addition, striking homozygosity is observed in the inbred families for markers neighboring TGM1, defining a 9.3 cM candidate region which is bounded by MYH7 and D14S275. This is the first report of linkage in LI and suggests that further study of the TGM1 gene may identify the underlying pathogenesis of this severe, disfiguring disorder. Linkage-based genetic counseling and prenatal diagnosis is now available for informative at-risk families.

  4. Candida albicans interface infection after deep anterior lamellar keratoplasty

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Sedaghat

    2012-01-01

    Full Text Available The clinical features of interface Candida keratitis after deep anterior lamellar keratoplasty (DALK, may imitate rejection or crystalline keratopathy. We report here an 18-year-old woman presented with red eye, 4 months after undergoing DALK. Slit lamp examination revealed keratic precipitates (KPs and cojunctival injection. She was prescribed corticosteroid treatment for endothelial rejection by another ophthalmologist because of misdiagnosis, but suffered a recurrence of symptoms after reduction of the corticosteroid treatment. At that time, she was referred to our office. The recurrence persisted despite antibiotic and antifungal therapies. Ten days after treatment with interface irrigation with amphotericin, the infiltration and hypopyon were resolved. Topical steroid was added after 3 months of antifungal monotherapy. Irrigant cultures confirmed the presence of Candida albicans. The corneal graft appeared semi-clear with no signs of infection at 17-month follow-up. We recommend a close follow-up and a timely intervention to prevent the need for more invasive treatment such as penetrating keratoplasty.

  5. Graft epithelial defects after deep anterior lamellar keratoplasty.

    Science.gov (United States)

    Feizi, Sepehr; Javadi, Fatemeh; Javadi, Mohammad Ali

    2014-11-01

    The aim of this study was to report the incidence of epithelial defects and identify donor factors that might correlate with the presence of epithelial defects and graft reepithelialization time after a deep anterior lamellar keratoplasty (DALK). In this retrospective study, 283 consecutive keratoconic eyes underwent DALK using donor corneas of different qualities, ranging from fair to excellent. The donor data included age and sex, cause of death, death-to-preservation time, preservation-to-surgery time, epithelial and stromal status, endothelial cell density and morphology, and graft rating. On the first postoperative day, the corneal surface was carefully examined before and after the application of fluorescein stain, and the patients were followed up daily until complete reepithelialization occurred. A multivariate regression analysis was used to assess the correlation between donor characteristics and graft epithelial defects on postoperative day 1. The mean donor and recipient ages were 33.5 ± 13.2 and 27.6 ± 7.9 years, respectively. Two hundred sixty-four (93.3%) grafts had epithelial defects on day 1. The epithelial defects completely healed after 3.5 ± 2.7 (range, 1-37) days. In the univariate analysis, the presence of epithelial defects on postoperative day 1 had a significant correlation with donor preservation-to-surgery time (P = 0.01), epithelial sloughing (P < 0.001), and graft rating (P = 0.004). In the multivariate analysis, only donor epithelial sloughing significantly influenced the presence of epithelial defects on postoperative day 1 (odds ratio = 9.26, P < 0.001). Graft epithelial defects were very common after DALK. The epithelial status of donors was the only independent factor predictive of the surface integrity on the first postoperative day.

  6. Factors predicting unsuccessful big bubble deep lamellar anterior keratoplasty.

    Science.gov (United States)

    Michieletto, Paolo; Balestrazzi, Alessandra; Balestrazzi, Angelo; Mazzotta, Cosimo; Occhipinti, Igor; Rossi, Tommaso

    2006-01-01

    To evaluate the role of corneal structural resistance as a surgical failure factor in deep lamellar keratoplasty (DLK). A total of 10 eyes of 10 patients underwent DLK at the Ophthalmic Hospital in Rome. The big bubble technique was performed for deep stromal dissection by air injection. Seven patients were affected by advanced keratoconus and corneal thinning ranging from 441 to 235 microm. Two patients were affected by central corneal opacity from herpetic keratitis, and one patient suffered from corneal leucoma caused by bacterial keratitis. Clinical follow-up comprising final astigmatism and visual acuity findings were evaluated with a minimum follow-up of 12 weeks. DLK was successfully performed in eight eyes, five of which were affected by moderate to advanced keratoconus and three by post-infective corneal opacity. In these patients preoperative ultrasonic pachymetry ranged between 441 and 287 microm. In the remaining two patients a perforation of the Descemet's membrane (DM) occurred while attempting to separate it from the overlying stroma by the big bubble technique, requiring a penetrating keratoplasty (PK) to be performed. In both cases preoperative ultrasonic pachymetry was below 250 microm. Both perforations occurred at a different site than the needle site and at the operative time of the big-bubble injection. An ultrastructurally weakened DM may suffer a loss of resistance to a stressing force, becoming unable to tolerate the big bubble technique, and thus being perforated. Since the weakening of the DM is related to end-stage keratoconus corneal thinning, the preoperative corneal thickness rather than the surgeon's ability can play a major role in surgical failure of DLK. Our study reveals a very high risk of perforation of the DM when pre-operative total pachymetry is below limit of 250 microm. Copyright 2006 S. Karger AG, Basel.

  7. Deep lamellar endothelial keratoplasty: early complications and their management.

    Science.gov (United States)

    Terry, Mark A; Ousley, Paula J

    2006-01-01

    To report the early vision-threatening complications in a large series of deep lamellar endothelial keratoplasty (DLEK) procedures and discuss the management of these complications. The first 100 consecutive patients to reach the 6-month postoperative gate of a prospective, institutional review board-approved protocol for DLEK surgery were reviewed for intraoperative and postoperative complications. The method of treatment of these complications and the outcome of that treatment were recorded. Two eyes (2 of 100 = 2%) were converted to PK at the time of DLEK surgery. Of the 98 patients who had complete DLEK surgeries, 4 eyes (4 of 98 = 4%) were noted to have a dislocated disk on the first postoperative day. The dislocated disk in each case was repositioned in a short, often topical anesthesia technique, and all corneas cleared. One eye had primary graft failure (caused by surgeon error) resulting in disk dislocation. It was successfully replaced with another disk on postoperative day 1. Four patients (4 of 98 = 4%) experienced graft rejection of the donor disk from stopping steroids, but all grafts cleared with restarting of steroids. One patient required surgery for steroid-aggravated glaucoma. In the 5 cases of DLEK surgery in which the clear crystalline lens was left in place, no cataracts were induced at the 6-month postoperative gate. There were no infections, ulcerations, healing defects, or late dislocations. No patient required a contact lens, relaxing incision, or LASIK for residual refractive error. DLEK surgery is technically challenging, and yet complications from the surgery in our series were relatively rare and easily resolved. By eliminating sutures and high astigmatism, DLEK surgery avoids the usual complications often associated with transplant surgery.

  8. Vacuolar ATPase regulates surfactant secretion in rat alveolar type II cells by modulating lamellar body calcium.

    Directory of Open Access Journals (Sweden)

    Narendranath Reddy Chintagari

    2010-02-01

    Full Text Available Lung surfactant reduces surface tension and maintains the stability of alveoli. How surfactant is released from alveolar epithelial type II cells is not fully understood. Vacuolar ATPase (V-ATPase is the enzyme responsible for pumping H(+ into lamellar bodies and is required for the processing of surfactant proteins and the packaging of surfactant lipids. However, its role in lung surfactant secretion is unknown. Proteomic analysis revealed that vacuolar ATPase (V-ATPase dominated the alveolar type II cell lipid raft proteome. Western blotting confirmed the association of V-ATPase a1 and B1/2 subunits with lipid rafts and their enrichment in lamellar bodies. The dissipation of lamellar body pH gradient by Bafilomycin A1 (Baf A1, an inhibitor of V-ATPase, increased surfactant secretion. Baf A1-stimulated secretion was blocked by the intracellular Ca(2+ chelator, BAPTA-AM, the protein kinase C (PKC inhibitor, staurosporine, and the Ca(2+/calmodulin-dependent protein kinase II (CaMKII, KN-62. Baf A1 induced Ca(2+ release from isolated lamellar bodies. Thapsigargin reduced the Baf A1-induced secretion, indicating cross-talk between lamellar body and endoplasmic reticulum Ca(2+ pools. Stimulation of type II cells with surfactant secretagogues dissipated the pH gradient across lamellar bodies and disassembled the V-ATPase complex, indicating the physiological relevance of the V-ATPase-mediated surfactant secretion. Finally, silencing of V-ATPase a1 and B2 subunits decreased stimulated surfactant secretion, indicating that these subunits were crucial for surfactant secretion. We conclude that V-ATPase regulates surfactant secretion via an increased Ca(2+ mobilization from lamellar bodies and endoplasmic reticulum, and the activation of PKC and CaMKII. Our finding revealed a previously unrealized role of V-ATPase in surfactant secretion.

  9. Incidental Finding of Lamellar Calcification of the Falx Cerebri Leading to the Diagnosis of Gorlin-Goltz Syndrome

    Directory of Open Access Journals (Sweden)

    I. Saulite

    2013-10-01

    Full Text Available Here, we report the case of an incidental finding of lamellar calcification of the falx cerebri in a routine computed tomography scan of the head after an accidental trauma. This lamellar calcification led to the diagnosis of Gorlin-Goltz syndrome (GGS in the patient and her daughter. Lamellar calcification of the falx cerebri is a pathognomonic feature of GGS. Our case report highlights the importance of a multidisciplinary diagnostic approach to GGS.

  10. Morphological instability of lamellar structures in directionally solidified Ni-Ni3Si alloys

    Science.gov (United States)

    Wei, Lufeng; Zhao, Zhilong; Gao, Jianjun; Cui, Kai; Guo, Jingying; Chen, Sen; Liu, Lin

    2018-02-01

    The morphological instability of lamellar structures in Ni-Ni3Si eutectic and hypereutectic alloys directionally solidified at low growth rates was investigated. The first instability in large lamellar structures was zigzag instability, which formed curved lamellae. A zigzag pattern was first displayed in three dimensions. The diffusion-limited growth of the Ni3Si phase decreased phase width and spacing, consequently causing zigzag instability. The reduced spacing was observed at λ/λave = 0.9. After zigzag instability, the microstructure of the eutectic alloy turned into a labyrinth structure and lamellar fragmentation. However, in hypereutectic alloys, shape transition from lamellae to rods occurred, in turn, by the broken lamellae or elongated rods to dumbbell-shaped rods, peanut-shaped rods, and circular rods.

  11. Unusual early recurrence of granular dystrophy after deep anterior lamellar keratoplasty: case report

    Directory of Open Access Journals (Sweden)

    Paolo Rama

    2013-04-01

    Full Text Available We report an atypical case of granular corneal dystrophy recurrence after deep anterior lamellar keratoplasty. We describe clinical features, histopathological analysis of the lamellar graft specimen and DNA analysis results. The slit-lamp examination and histopathological findings from the graft specimen indicated the confinement of the typical deposits of granular corneal dystrophy deep in the graft interface area. This localization is atypical, since in most cases recurrences in grafts tend to be initially superficial and situated in the epithelial or subepithelial corneal layers. Molecular genetic analysis revealed an already described mutation and a new intronic variant. The unusual localization and timing of this recurrence of granular corneal dystrophy after deep anterior lamellar keratoplasty suggests that corneal stromal keratocytes may play a role in the formation of granular deposits.

  12. One- and two-dimensional fluids properties of smectic, lamellar and columnar liquid crystals

    CERN Document Server

    Jakli, Antal

    2006-01-01

    Smectic and lamellar liquid crystals are three-dimensional layered structures in which each layer behaves as a two-dimensional fluid. Because of their reduced dimensionality they have unique physical properties and challenging theoretical descriptions, and are the subject of much current research. One- and Two-Dimensional Fluids: Properties of Smectic, Lamellar and Columnar Liquid Crystals offers a comprehensive review of these phases and their applications. The book details the basic structures and properties of one- and two-dimensional fluids and the nature of phase transitions. The later chapters consider the optical, magnetic, and electrical properties of special structures, including uniformly and non-uniformly aligned anisotropic films, lyotropic lamellar systems, helical and chiral structures, and organic anisotropic materials. Topics also include typical and defective features, magnetic susceptibility, and electrical conductivity. The book concludes with a review of current and potential applications ...

  13. Microstructure transition from lamellar to compacted graphite using different modification agents

    Energy Technology Data Exchange (ETDEWEB)

    Geier, G.F. [Austrian Foundry Research Institute, Parkstrasse 21, 8700 Leoben (Austria)]. E-mail: geier.ogi@unileoben.ac.at; Bauer, W. [Austrian Foundry Research Institute, Parkstrasse 21, 8700 Leoben (Austria); McKay, B.J. [University of Leoben, Lehrstuhl fuer Giessereikunde, Franz-Josef-St. 18, 8700 Leoben (Austria); Schumacher, P. [Austrian Foundry Research Institute, Parkstrasse 21, 8700 Leoben (Austria); University of Leoben, Lehrstuhl fuer Giessereikunde, Franz-Josef-St. 18, 8700 Leoben (Austria)

    2005-12-15

    The graphite morphology present in compacted graphite irons can vary between a spheroidal and lamellar range of shapes. These graphite shapes have been studied by scanning electron microscopy (SEM). Samples used were treated either with magnesium, cerium or lanthanum to investigate differences in the modification of the graphite structure between each of these elements. To facilitate the SEM study the samples were deep etched to reveal the graphite structure in three dimensions. Results showed that there was little difference between the morphologies displayed in the well-formed compacted graphite. However, the lamellar graphite formed varied considerably with each of the three modification agents. The transition from compacted to lamellar shape was continuous for Mg treatment, whereas there was a sharp transition when treated with rare earth elements. Furthermore, several degenerated graphite structures in the La-treated sample were observed.

  14. Deep anterior lamellar keratoplasty for the management of iatrogenic keratectasia occurring after hexagonal keratotomy

    Directory of Open Access Journals (Sweden)

    Paras Mehta

    2012-01-01

    Full Text Available Iatrogenic keratectasia has been reported subsequent to refractive surgery or trauma. Hexagonal keratotomy (HK is a surgical incisional technique to correct hyperopia. A number of complications have been reported following this procedure, including irregular astigmatism, wound healing abnormalities and corneal ectasia. When visual acuity is poor because of ectasia or irregular astigmatism and contact lens fitting is not possible, penetrating or lamellar keratoplasty can be performed. Since incisions in refractive keratotomy are set at 90-95% depth of cornea, intraoperative microperforations are known to occur and lamellar keratoplasty may become difficult. We describe deep anterior lamellar keratoplasty (DALK used to successfully manage keratectasia after HK. Pre DALK vision was 20/400 and post DALK vision was 20/30 two months after surgery. This report aims to show improved visual outcome in corneal ectasia secondary to HK. DALK can be a procedure of choice with proper case selection.

  15. Deep anterior lamellar keratoplasty versus penetrating keratoplasty for treating keratoconus.

    Science.gov (United States)

    Keane, Miriam; Coster, Douglas; Ziaei, Mohammed; Williams, Keryn

    2014-07-22

    Keratoconus is an ectatic (weakening) disease of the cornea, which is the clear surface at the front of the eye. Approximately 10% to 15% of patients diagnosed with keratoconus require corneal transplantation. This may be full-thickness (penetrating) or partial-thickness (lamellar). To compare visual outcomes after deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty for keratoconus, and to compare additional outcomes relating to factors which may contribute to poor visual outcomes (e.g. astigmatism, graft rejection and failure). We searched a number of electronic databases including CENTRAL, PubMed and EMBASE without using any date or language restrictions. We last searched the electronic databases on 31 October 2013. We also handsearched the proceedings of several international ophthalmic conferences. We included all randomised controlled trials (RCTs) comparing the outcomes of DALK and penetrating keratoplasty in the treatment of keratoconus. Two authors assessed trial quality and extracted data independently. For dichotomous data (graft failure, rejection, achievement of functional vision) results were expressed as odds ratios (ORs) and 95% confidence intervals (CIs). For continuous data (postoperative best corrected visual acuity (BCVA), uncorrected visual acuity (UCVA), keratometric astigmatism and spherical equivalent) results were expressed as mean differences (MDs) and 95% CIs. We identified two completed studies, with a total of 111 participants (n = 30 and n = 81), both conducted in Iran, that met our inclusion criteria. Participants had moderate to severe keratoconus pre-operatively and were randomly allocated to receive either DALK or penetrating keratoplasty. Only one eye of each participant was treated as part of the trials. The smaller study had 12 month follow-up data for all participants. For the larger study, four DALK surgeries had to be abandoned due to technical failure and visual and refractive outcomes were not measured in

  16. Lamellar-in-lamellar self-assembled C-b-(B-b-A)(m)-b-B-b-C multiblock copolymers : Alexander-de Gennes approach and dissipative particle dynamics simulations

    NARCIS (Netherlands)

    Klymko, Tetyana; Markov, Vladimir; Subbotin, Andrei; ten Brinke, Gerrit

    2009-01-01

    A simple theoretical analysis of the lamellar-in-lamellar self-assembled state of ternary C-b-(B-b-A)(m)-b-B-b-C multiblock copolymer melts in the strong segregation limit is presented using the Alexander de Gennes approximation. For a given value of m, the influence of the chain length of the

  17. Femtosecond laser-assisted lamellar keratoplasty Transplante lamelar auxiliado pelo laser de fentosegundo

    Directory of Open Access Journals (Sweden)

    Hunson Kaz Soong

    2008-08-01

    Full Text Available Lamellar keratoplasty consists of transplanting partial-thickness donor cornea onto a complementary recipient bed. Manual lamellar dissection is technically very difficult, time-consuming, and imprecise. Also, the manually-dissected lamellar interface often has topographical irregularities that may optically degrade the best-corrected visual acuity. The femtosecond clinical laser (IntraLase FS LaserTM, Irvine, CA is a recent innovation that can be programmed to produce bladeless, precise lamellar cuts at any depth with accompanying trephination cuts for both anterior and posterior lamellar transplantion. Posterior laser cuts may be used to assist in deep lamellar endothelial keratoplasty or Descemet's stripping automated endothelial keratoplasty.A ceratoplastia lamelar consiste em transplante de espessura parcial da córnea doadora em um leito receptor complementar. A dissecção lamelar manual é técnica de difícil realização, imprecisa e que demanda tempo. Além disso, a interface lamelar freqüentemente apresenta irregularidade topográfica que pode comprometer a acuidade visual final. O laser clínico "femtosecond" (IntraLase FS LaserTM, Irvine, CA é uma recente inovação que pode ser utilizado para produzir cortes lamelares precisos em qualquer profundidade da córnea, acompanhados de cortes verticais tanto para transplantes lamelares anteriores como posteriores sem a utilização de lâminas. Os cortes posteriores podem ser utilizados para a realização de ceratoplastia endotelial lamelar profunda ou ceratoplastia endotelial com remoção da membrana de Descemet.

  18. Femtosecond Laser and Big-Bubble Deep Anterior Lamellar Keratoplasty: A New Chance

    OpenAIRE

    Luca Buzzonetti; Gianni Petrocelli; Paola Valente

    2012-01-01

    Purpose. To report the 12-month follow-up after big-bubble deep anterior lamellar keratoplasty (DALK) assisted by femtosecond laser that we have called IntraBubble. Methods. A 60 kHz IntraLase femtosecond laser (Abbott Medical Optics) firstly created a 30° angled intrastromal channel to insert the air injection cannula, 50 μ above the thinnest corneal site measured by Sirius Scheimpflug camera (CSO, Firenze, Italy), then performed a full lamellar cut 100 μ above the thinnest corneal point, an...

  19. Preparation and characterisation of polymeric lamellar substrate particles (PLSP)

    Energy Technology Data Exchange (ETDEWEB)

    Khairullah, Noor Hasnah Mohamed

    2002-07-01

    Polymer microparticles have tremendous potential as the next generation of adjuvant systems to replace the only adjuvant currently widely registered for human use, alum. Based on aluminium salts, alum adjuvants work as short-term depots of adsorbed protein/antigens that slowly 'leak' into the body's immune system, inducing immunity by invoking a humoral response. The main disadvantage of alum adjuvants is that they do not raise sufficient antibody levels to induce long-term immunity. Hence, booster administrations are required. This drawback presents the biggest factor in the failure of many vaccination programmes. Polymer microparticulate systems can be fashioned to deliver sub-unit and peptide antigens in a continuous or controlled rate over a desired period of time, avoiding the need for booster doses. The design of mucosal vaccines is now centred upon the use of these polymeric carriers. The mucosal route for immunisation has many advantages over the more conventional systemic route, the most important of which, is the induction of both humoral and cellular immunity. Polymer microspheres of sizes <10{mu}m are especially good candidates as oral vaccine adjuvants as they are taken up by the M cells of the Peyer's patches in the intestine. Numerous studies have been carried out on microspheres into which antigens have been encapsulated or entrapped. There are, however, problems associated with loss of antigenicity since formulation procedures involve the use of organic solvents and harsh shearing methods. Additionally, these antigens may be further degraded when the polymer material itself degrades in vivo and produces acidic species. A novel adjuvant system that avoids the above problems is currently being evaluated. Poly(l-lactide) (PLLA) polymeric lamellar substrate particles (PLSP) are promising as novel adjuvants for the controlled release of antigens. Reports have shown that the adsorption of antigens onto the surface of these particles

  20. Proteomics Core

    Data.gov (United States)

    Federal Laboratory Consortium — Proteomics Core is the central resource for mass spectrometry based proteomics within the NHLBI. The Core staff help collaborators design proteomics experiments in a...

  1. Improved resolution for soft-x-ray monochromatization using lamellar multilayer gratings

    NARCIS (Netherlands)

    van der Meer, R.; Krishnan, B.; Kozhevnikov, I.V.; de Boer, Meint J.; Vratzov, B.; Bastiaens, Hubertus M.J.; Huskens, Jurriaan; van der Wiel, Wilfred Gerard; Hegeman, P.E.; Brons, G.C.S.; Boller, Klaus J.; Bijkerk, Frederik; Morawe, Christian; Khounsary, Ali M.; Goto, Shunji

    2011-01-01

    Lamellar Multilayer Gratings (LMG) offer improved resolution for soft-x-ray (SXR) monochromatization, while maintaining a high reflection efficiency in comparison to conventional multilayer mirrors (MM). We previously used a Coupled-Waves Approach (CWA) to calculate SXR diffraction by LMGs and

  2. Development of porous lamellar poly(L-lactic acid) scaffolds by conventional injection molding process.

    Science.gov (United States)

    Ghosh, Satyabrata; Viana, Júlio C; Reis, Rui L; Mano, João F

    2008-07-01

    A novel fabrication technique is proposed for the preparation of unidirectionally oriented, porous scaffolds by selective polymer leaching from lamellar structures created by conventional injection molding. The proof of the concept is implemented using a 50/50 wt.% poly(L-lactic acid)/poly(ethylene oxide) (PLLA/PEO) blend. With this composition, the PLLA and PEO blend is biphasic, containing a homogeneous PLLA/PEO phase and a PEO-rich phase. The two phases were structured using injection molding into well-defined alternating layers of homogeneous PLLA/PEO phase and PEO-rich phase. Leaching of water-soluble PEO from the PEO-rich phase produces macropores, and leaching of phase-separated PEO from the initially homogeneous PLLA/PEO phase produces micropores in the lamellae. Thus, scaffolds with a macroporous lamellar architecture with microporous walls can be produced. The lamellae are continuous along the flow direction, and a continuous lamellar thickness of less than 1 microm could be achieved. Porosities of 57-74% and pore sizes of around 50-100 microm can be obtained using this process. The tensile elastic moduli of the porous constructs were between 580 and 800 MPa. We propose that this organic-solvent-free method of preparing lamellar scaffolds with good mechanical properties, and the reproducibility associated with the injection molding technique, holds promise for a wide range of guided tissue engineering applications.

  3. Lamellar Diblock Copolymer Thin Films during Solvent Vapor Annealing Studied by GISAXS

    DEFF Research Database (Denmark)

    Zhang, Jianqi; Posselt, Dorthe; Smilgies, Detlef-M.

    2014-01-01

    The reorientation of lamellae and the dependence of the lamellar spacing, Dlam, on polymer volume fraction, ϕP, Dlam ∝ ϕP–β, in diblock copolymer thin films during solvent vapor annealing (SVA) are examined by combining white light interferometry (WLI) and grazing-incidence small-angle X-ray scat...

  4. Effect of the Molecular Weight of AB Diblock Copolymers on the Lamellar Orientation in Thin Films

    DEFF Research Database (Denmark)

    Potemkin, Igor I.; Busch, Peter; Smilgies, Detlef-M

    2007-01-01

    We propose a theoretical explanation of the parallel and perpendicular lamellar orientations in free surface films of symmetric polystyrene-block-polybutadiene diblock copolymers on silicon substrates (with a native SiOx layer). Two approaches are developed: A correction to the strong segregation...

  5. Reconstruction of auto-tissue-engineered lamellar cornea by dynamic culture for transplantation: a rabbit model.

    Science.gov (United States)

    Wu, Zheng; Zhou, Qiang; Duan, Haoyun; Wang, Xiaoran; Xiao, Jianhui; Duan, Hucheng; Li, Naiyang; Li, Chaoyang; Wan, Pengxia; Liu, Ying; Song, Yiyue; Zhou, Chenjing; Huang, Zheqian; Wang, Zhichong

    2014-01-01

    To construct an auto-tissue-engineered lamellar cornea (ATELC) for transplantation, based on acellular porcine corneal stroma and autologous corneal limbal explants, a dynamic culture process, which composed of a submersion culture, a perfusion culture and a dynamic air-liquid interface culture, was performed using appropriate parameters. The results showed that the ATELC-Dynamic possessed histological structure and DNA content that were similar to native lamellar cornea (NLC, p>0.05). Compared to NLC, the protein contents of zonula occludens-1, desmocollin-2 and integrin β4 in ATELC-Dynamic reached 93%, 89% and 73%, respectively. The basal cells of ATELC-Dynamic showed a better differentiation phenotype (K3-, P63+, ABCG2+) compared with that of ATELC in static air-lift culture (ATELC-Static, K3+, P63-, ABCG2-). Accordingly, the cell-cloning efficiency of ATELC-Dynamic (9.72±3.5%) was significantly higher than that of ATELC-Static (2.13±1.46%, p0.05). Rabbit lamellar keratoplasty showed that the barrier function of ATELC-Dynamic was intact, and there were no signs of epithelial shedding or neovascularization. Furthermore, the ATELC-Dynamic group had similar optical properties and wound healing processes compared with the NLC group. Thus, the sequential dynamic culture process that was designed according to corneal physiological characteristics could successfully reconstruct an auto-lamellar cornea with favorable morphological characteristics and satisfactory physiological function.

  6. Endothelial replacement without surface corneal incisions or sutures: topography of the deep lamellar endothelial keratoplasty procedure.

    Science.gov (United States)

    Terry, M A; Ousley, P J

    2001-01-01

    To evaluate the immediate postoperative corneal topography after the deep lamellar endothelial keratoplasty procedure. Eight eye bank eyes underwent deep lamellar endothelial keratoplasty through a 9.0-mm limbal incision replacing the central 7.0 mm of posterior stroma and endothelium through the lamellar pocket wound. Orbscan topography was performed before and after surgery, and simulated keratometry readings and central corneal diopter power were recorded. The change in astigmatism and corneal power from preoperative to postoperative readings was then determined. The net change in corneal astigmatism averaged 0.4+/-0.5 diopters (range, -0.1 to 1.1 diopters). The net change in corneal power averaged -0.2+/-0.4 diopters of flattening (range, -0.9 to +0.2 diopters). Neither the astigmatism nor the corneal power levels after this surgery were significantly different from the preoperative topography (p = 0.22 and 0.27, respectively). The deep lamellar endothelial keratoplasty procedure, with its absence of corneal surface incisions or sutures, has no significant effect on immediate postoperative corneal topography. The potential advantages of this procedure over penetrating keratoplasty in the treatment of endothelial dysfunction are considerable.

  7. A specific acid [alpha]-glucosidase in lamellar bodies of the human lung

    NARCIS (Netherlands)

    Vries, A.C.J. de; Schram, A.W.; Tager, J.M.; Batenburg, J.J.

    2006-01-01

    In the present investigation, we have demonstrated that three lysosomal-type hydrolases, alpha-glucosidase, alpha-mannosidase and a phosphatase, are present in lamellar bodies isolated from adult human lung. The hydrolase activities that were studied, all showed an acidic pH optimum, which is

  8. Anterior lamellar keratoplasty assisted by IntraLase™ femtosecond laser in a pediatric patient.

    Science.gov (United States)

    Buzzonetti, Luca; Petrocelli, Gianni; Laborante, Antonio

    2010-05-21

    A 14-year-old boy affected by keratoconus underwent an anterior lamellar keratoplasty assisted by IntraLase femtosecond laser (Abbott Medical Optics, Abbott Park, IL). Results after 2 years of follow-up indicate the procedure may be safe and effective in pediatric patients. Copyright 2010, SLACK Incorporated.

  9. Lecithin/sphingomyelin ratio and lamellar body count for fetal lung maturity: a meta-analysis

    NARCIS (Netherlands)

    Besnard, Anouk E.; Wirjosoekarto, Soetinah A. M.; Broeze, Kimiko A.; Opmeer, Brent C.; Mol, Ben Willem J.

    2013-01-01

    To determine and compare the diagnostic accuracy of the lecithin/sphingomyelin (L/S) ratio and lamellar body count (LBC) in the prediction of neonatal respiratory distress syndrome (RDS). A systematic review was performed to identify studies comparing either the L/S ratio or the LBC with the

  10. More than skin deep: a case of congenital lamellar ichthyosis, lymphatic malformation, and other abnormalities.

    Science.gov (United States)

    Small, Katherine; Ginsburg, Howard; Greco, M Alba; Sarita-Reyes, Carmen; Kupchik, Gabriel; Blei, Francine

    2008-01-01

    Consanguinity allows for the expression of rare genetic disorders. We present the first case of an infant, born to consanguineous parents, with congenital lamellar ichthyosis, congenital lymphatic malformation, congenital hypothyroidism, bilateral megaureter, benign external hydrocephalus, and syrinx of the spinal cord. We review the disorders, examine their genetic causes, and explore the genetic connection among them.

  11. Investigation on the Effect of Sulfur and Titanium on the Microstructure of Lamellar Graphite Iron

    DEFF Research Database (Denmark)

    Moumeni, Elham; Stefanescu, Doru Michael; Tiedje, Niels Skat

    2013-01-01

    The goal of this work was to identify the inclusions in lamellar graphite cast iron in an effort to explain the nucleation of the phases of interest. Four samples of approximately the same carbon equivalent but different levels of sulfur and titanium were studied. The Ti/S ratios were from 0.15 t...

  12. Early surfactant guided by lamellar body counts on gastric aspirate in very preterm infants

    DEFF Research Database (Denmark)

    Verder, Henrik Axel; Ebbesen, Finn; Fenger-Grøn, Jesper

    2013-01-01

    We have developed a rapid method, based on lamellar body counts (LBC) on gastric aspirate, for identifying newborns who will develop respiratory distress syndrome with a need for surfactant supplementation. Objective: We set out to test whether it was possible to improve the outcome when used...

  13. Chain elongation suppression of cyclic block copolymers in lamellar microphase-separated bulk

    NARCIS (Netherlands)

    Matsushita, Y; Iwata, H; Asari, T; Uchida, T; ten Brinke, G; Takano, A

    2004-01-01

    Chain elongation suppression of cyclic block copolymers in microphase-separated bulk was determined quantitatively. Solvent-cast and annealed films are confirmed to show alternating lamellar structure and their microdomain spacing D increases with increasing total molecular weight M according to the

  14. Chain confinement, phase transitions, and lamellar structure in semicrystalline polymers, polymer blends and polymer nanocomposites

    Science.gov (United States)

    Chen, Huipeng

    Recent studies suggest that there are three phase fractions in semicrystalline polymers, the crystalline, the mobile amorphous and the rigid amorphous phases. Due to the distinct properties of the rigid amorphous fraction, RAF, it has been investigated for more than twenty years. In this thesis, a general method using quasi-isothermal temperature-modulated differential scaning calorimetry, DSC, is provided for the first time to obtain the temperature dependent RAF and the other two fractions, crystalline fraction and mobile amorphous fraction, MAF. For poly(ethylene terephthalate), PET, our results show RAF was vitrified during quasi-isothermal cooling after crystallization had been completed and became totally devitrified during quasi-isothermal heating before the start of melting. Several years after people initially discovered the existence of RAF, another issue arose relating to the physical location of RAF and mobile amorphous fraction, MAF, within a lamellar stack model. Two very different models to describe the location of RAF were proposed. In the Heterogeneous Stack Model, HET, RAF is located outside the lamellar stacks. In the Homogeneous Stack Model, HSM, RAF was located inside the lamellar stacks. To determine the lamellar structure of semicrystalline polymers comprising three phase, a general method is given in this thesis by using a combination of the DSC and small angle X-ray scattering, SAXS techniques. It has been applied to Nylon 6, isotactic polystyrene, iPS, and PET. It was found for all of these materials, the HSM model is correct to describe the lamellar structure. In addition to the determination of lamellar structures, this method can also provide the exact fraction of MAF inside and outside lamellar stacks for binary polymer blends. For binary polymer blends, MAF, normally is located partially inside and partially outside the lamellar stacks. However, the quantification of the MAF inside and outside the lamellar stacks has now been provided

  15. Refractive outcomes of penetrating keratoplasty and deep anterior lamellar keratoplasty in fellow eyes for keratoconus.

    Science.gov (United States)

    Pedrotti, Emilio; Passilongo, Mattia; Fasolo, Adriano; Ficial, Sara; Ferrari, Stefano; Marchini, Giorgio

    2017-08-01

    To compare the refractive outcomes following penetrating keratoplasty and deep anterior lamellar keratoplasty in fellow eyes in patients with keratoconus. This is an observational retrospective review of consecutive patients with keratoconus first managed with penetrating keratoplasty in one eye and then with lamellar keratoplasty in the fellow eye, between 2002 and 2007. Data collection was based on patients' hospital records. Information related to assessment before surgery and at 1, 3, 6, 12, 24, and 48 months after keratoplasty were retrieved and considered in the analysis. Clinical evaluations included patients' medical histories and diagnosis of keratoconus, uncorrected and best corrected visual acuity, spherical equivalent, refractive cylinder, topographic cylinder, and high-order aberrations, complications, and adverse reactions. Data on contrast sensitivity, central corneal thickness, and central residual bed thickness (only for lamellar keratoplasty) were retrieved from anterior segment optical coherence tomography observation performed at 48 months. Sixteen patients (32 eyes), 7 males and 9 females, were included in the analyses. After 4 years from transplantation, at the end of follow-up, no statistically significant differences were found in visual acuity and refractive measures between the two keratoplasties. Perforating keratoplasty showed significant differences for contrast sensitivity at 6 cpd with maximum glare (p = 0.026) and without glare (p = 0.015). Deep anterior lamellar keratoplasty showed a negative correlation between central residual bed thickness and best corrected visual acuity (R = -0.414, p < 0.001). The manual pre-descemetic deep anterior lamellar keratoplasty used in this study showed refractive and visual results comparable to those obtained with penetrating keratoplasty. Such results indicated that leaving healthy stroma attached to Descemet's membrane does not compromise the clinical outcome in the short and long

  16. Deep anterior lamellar keratoplasty using precut anterior lamellar cap for herpes simplex keratitis: a long-term follow-up study.

    Science.gov (United States)

    Li, Jinyang; Ma, Huixiang; Zhao, Zelin; Hou, Chao; Shao, Yumei; Waller, Stephen; Chen, Wei

    2014-04-01

    To evaluate the feasibility, safety and efficacy of deep anterior lamellar keratoplasty (DALK) using precut anterior lamellar cap (ALC) for patients with herpes simplex keratitis. In this single-centre retrospective study, 48 consecutive patients with herpes simplex keratitis and having undergone DALK using either big bubble technique or manual lamellar dissection, between February 2009 and March 2010, were included. Each patient received DALK using either a precut ALC or a full-thickness stroma (FTS), and completed a minimum follow-up time of 36 months. There were no significant differences in the age, sex, eyes and sizes of trephination between two groups. Postoperative best spectacle-corrected visual acuity of 0.3 logarithm of the minimum angle of resolution or better at the last follow-up visit was achieved in 74.1% of eyes in the FTS group and 71.4% in the ALC group (p=0.84). The mean central corneal thickness and corneal volume were significantly higher in the FTS group (550.7 ± 34.3 µm and 61.21 ± 4.12 mm(3)) than the ALC group (393 ± 45.7 µm and 54.68 ± 4.55 mm(3); pbiomechanical behaviour of two types of corneal tissues after DALK. Corneal curvature remained stable in the ALC group, and no signs of corneal ectasia were observed during follow-ups. DALK using precut ALC should be considered as a selective surgical approach. A postoperative subnormal central corneal thickness of about 400 µm would not influence corneal curvature and refractive status.

  17. Development of Ultrafine, Lamellar Structures in Two-Phase {gamma}-TiAl Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Maziasz, P.J., Liu, C.T.

    1997-12-31

    Processing of two-phase gamma-TiAl alloys (Ti-47Al-2Cr-2Nb or minor modifications thereof) above the alpha-transus temperature (T {sub alpha}) produced unique refined-colony/ultrafine lamellar structures in both powder- and ingot-metallurgy (P/M and I/M, respectively) alloys. These ultrafine lamellar structures consist of fine laths of the gamma and alpha {sub 2} phases, with average interlamellar spacings (lambda {sub Lambda}) of 100-200 nm and alpha {sub 2}-alpha {sub 2} spacings (lambda {sub alpha}) of 200-500 nm, and are dominated by gamma/alpha {sub 2} interfaces. This characteristic microstructure forms by extruding P/M Ti-47Al-2Cr-2Nb alloys above T {sub alpha}, and also forms with finer colony size but slightly coarser fully-lamellar structures by hot-extruding similar I/M alloys. Alloying additions of B and W refine lambda {sub L} and lambda {sub alpha} in both I/M Ti-47Al (cast and heat-treated above T {sub alpha}) or in extruded Ti-47Al-2Cr-2Nb alloys. The ultrafine lamellar structure in the P/M alloy remains stable during heat-treatment at 900 {degrees}C for 2h, but becomes unstable after 4h at 982 {degrees}C; the ultrafine lamellar structure remains relatively stable after aging for {gt}5000 h at 800 {degrees}C. Additions of B+W dramatically improve the coarsening resistance of lambda L and lambda alpha in the I/M Ti-47Al alloys aged for 168 h at 1000{degrees}C. In both the P/M and I/M Ti-47Al-2Cr-2Nb alloys, these refined-colony/ultrafine-lamellar structures correlate with high strength and good ductility at room temperature, and very good strength at high temperatures. While refining the colony size improves the room-temperature ductility, alloys with finer lambda {sub L} are stronger at both room- and high-temperatures. Additions of B+W produce finer as-processed lambda {sub L} and lambda {sub alpha} in I/M TiAl alloys, and stabilize such structures during heat-treatment or aging.

  18. Ice cores

    DEFF Research Database (Denmark)

    Svensson, Anders

    2014-01-01

    Ice cores from Antarctica, from Greenland, and from a number of smaller glaciers around the world yield a wealth of information on past climates and environments. Ice cores offer unique records on past temperatures, atmospheric composition (including greenhouse gases), volcanism, solar activity......, dustiness, and biomass burning, among others. In Antarctica, ice cores extend back more than 800,000 years before present (Jouzel et al. 2007), whereas. Greenland ice cores cover the last 130,000 years...

  19. Endothelial cell loss and visual outcome of deep anterior lamellar keratoplasty versus penetrating keratoplasty: a randomized multicenter clinical trial

    NARCIS (Netherlands)

    Cheng, Y.Y.; Visser, N.; Schouten, J.S.A.G.; Wijdh, R.J.; Pels, E.; Cleynenbreugel, H. van; Eggink, C.A.; Zaal, M.J.; Rijneveld, W.J.; Nuijts, R.M.

    2011-01-01

    OBJECTIVE: To compare endothelial cell (EC) loss, visual and refractive outcomes, and complications after deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK). DESIGN: Randomized, multicenter clinical trial. PARTICIPANTS: Fifty-six eyes of 56 patients with a corneal stromal

  20. Endothelial Cell Loss and Visual Outcome of Deep Anterior Lamellar Keratoplasty versus Penetrating Keratoplasty : A Randomized Multicenter Clinical Trial

    NARCIS (Netherlands)

    Cheng, Yanny Y. Y.; Visser, Nienke; Schouten, Jan S.; Wijdh, Robert-Jan; Pels, Elisabeth; van Cleynenbreugel, Hugo; Eggink, Catharina A.; Zaal, Michel J. W.; Rijneveld, Wilhelmina J.; Nuijts, Rudy M. M. A.

    Objective: To compare endothelial cell (EC) loss, visual and refractive outcomes, and complications after deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK). Design: Randomized, multicenter clinical trial. Participants: Fifty-six eyes of 56 patients with a corneal stromal

  1. Structural rearrangements in a lamellar diblock copolymer thin film during treatment with saturated solvent vapor

    Science.gov (United States)

    Di, Zhenyu; Posselt, Dorthe; Smilgies, Detlef-M.; Papadakis, Christine M.

    2010-01-01

    We have investigated the structural changes in thin films of lamellar poly(styrene-b-butadiene) diblock copolymers during treatment with saturated cyclohexane vapor, a solvent slightly selective for polybutadiene. Using real-time, in-situ grazing-incidence small-angle X-ray scattering (GISAXS), the swelling and the rearrangement of the lamellae were investigated with a time resolution of a few seconds, and the underlying processes on the molecular level were identified. After a few minutes in vapor, a transient state with a more well-defined and more long-range ordered lamellar orientation was encountered. Additional parallel lamellae formed which we attribute to the increased degree of coiling of the polymers in the swollen state. Eventually, the film became disordered. These changes are attributed to the increased mobility of the swollen polymers and the gradually decreasing segment-segment interaction parameter in the film as solvent is absorbed. PMID:20305742

  2. Intraocular pressure and corneal biomechanics in Fuchs' endothelial dystrophy and after posterior lamellar keratoplasty.

    Science.gov (United States)

    Clemmensen, Kåre; Hjortdal, Jesper

    2014-06-01

      To evaluate the precision of techniques for measuring intraocular pressure (IOP) in corneas with presumably altered biomechanical properties.   Intraocular pressure was measured with a Goldmann applanation tonometer (GAT), ocular response analyzer (ORA) and dynamic contour tonometer (DCT) in 70 eyes. Thirty-five eyes were normal corneas, 18 eyes had Fuchs' endothelial dystrophy, and 17 eyes had undergone Descemet's stripping automated endothelial keratoplasty (DSAEK) surgery. Corneal hysteresis (CH), corneal resistance factor (CRF) as well as central corneal thickness (CCT) were recorded with the ORA.   The measured cornea-corrected IOP using ORA was significantly higher than GAT in all three groups (pkeratoplasty. GAT and DCT seem to measure IOP correctly in patients with Fuchs' endothelial dystrophy as well as after posterior lamellar keratoplasty. Corneal-corrected IOP as measured with the ORA appears to overestimate IOP in patients with Fuchs' endothelial dystrophy as well as after posterior lamellar keratoplasty. © 2013 Acta Ophthalmologica Scandinavica Foundation. Published by Blackwell Publishing Ltd.

  3. Growth of ordered lamellar precipitates during nitridation of Nb-10 at.% Ti at 1300 C

    Energy Technology Data Exchange (ETDEWEB)

    Buscaglia, V.; Martinelli, A.; Bottino, C. [Nat. Res. Council, Genoa (Italy). Inst. of Phys. Chem. of Mater.; Musenich, R. [National Institute of Nuclear Physics, via Dodecaneso 33, I-16146 Genoa (Italy)

    1999-02-01

    Growth of three morphologically distinct layers occurs during the parabolic nitridation of Nb-10 at.% Ti at 1300 C under 0.3 bar nitrogen atmosphere. The outermost layer is composed of {delta}-(Nb,Ti)N, the intermediate layer of {beta}-(Nb,Ti){sub 2}N and the innermost layer corresponds to an internal precipitation zone with ordered lamellar precipitates of {beta}-(Nb,Ti){sub 2}N+{beta}-(Nb,Ti). The internal precipitation front advances with parabolic kinetics and the three layers grow by nitrogen inward diffusion. The interlamellar spacing at the precipitation front increases as the reaction time increases. The formation of the lamellar microstructure can be described as a discontinuous precipitation process and the interlamellar spacing can be considered as a measure of the distance over which lateral Nb-Ti interdiffusion occurs in the alloy. (orig.) 25 refs.

  4. Multiscale damage and strength of lamellar bone modeled by cohesive finite elements.

    Science.gov (United States)

    Hamed, Elham; Jasiuk, Iwona

    2013-12-01

    A computational multiscale model of damage mechanisms and strength of lamellar bone is presented. The analysis incorporates the hierarchical structure of bone spanning the nanoscale (mineralized collagen fibril), the sub-microscale (single lamella) and the microscale (lamellar structure) levels. Due to the presence of several constituents (collagen, hydroxyapatite minerals, and non-collagenous proteins) and the different microstructural features at each scale, various deformation and failure mechanisms occur in bone at its several levels of hierarchy. The model takes into account the dominant damage mechanisms at the above mentioned three scales and predicts the strength of bone by using a cohesive finite element method. Elastic moduli of bone at these three different scales are also obtained as part of these calculations. The obtained modeling results compare well with other theoretical and experimental data available in the literature. © 2013 Elsevier Ltd. All rights reserved.

  5. Controlled alignment of lamellar lyotropic mesophases by rotation in a magnetic field.

    Science.gov (United States)

    Majewski, Paweł W; Osuji, Chinedum O

    2010-06-01

    We demonstrate a versatile approach to align lamellar lyotropic mesophases with the use of magnetic fields. It is based on continuous rotation of the sample on an axis perpendicular to the magnetic field direction during a single cooling ramp across the order-disorder transition of the system. The process yields materials with near-perfect, nondegenerate alignment of lamellar stacks along the axis of rotation. We use a model tetraethylene glycol dodecyl ether-water system to investigate the influence of magnetic field strength, cooling rate and the speed of sample rotation on the degree of alignment as quantitatively determined by small-angle X-ray scattering. This approach offers broad utility for the alignment of other soft mesophases relevant in several emerging applications.

  6. Size dependence and odd/even effect in the melting of 2D lamellar crystals

    Science.gov (United States)

    de Wit, Joeri Frederik

    2013-01-01

    The self-assembly of polymers into thin, crystalline lamellar sheets is of interest in the fundamental understanding of the properties of these materials. This research is a fundamental thermodynamic study of the self-assembly of these lamellar crystals. Our group has successfully developed a new synthesis method to grow lamellar crystals of silver alkanethiolates (AgSCn) on inert substrates with a precise control of the number of layers. The new vapor phase synthesis method systematically changes the amount of silver and the annealing temperature to grow monodisperse lamella with specific number of layers. Together with our unique capability to do thermal analysis of nanoscale systems using the nanocalorimetry (NanoDSC) technique, the size dependent melting and effects of layer stacking in AgSCn lamellar crystals are investigated. For single layer lamella, discrete change in the lamellar thickness is achieved by changing the alkanethiol chain length. Nanocalorimetry results show size-effect melting which follows an inverse linear relationship with the lamella thickness. The discrete thickness change leads to a discrete change in the melting point. This behavior is analogous to magic size melting observed in 3D metal nanoparticles. Layer-to-layer stacking significantly changes the melting behavior of the lamellar crystals. There is a large increase (DeltaT=23K for AgSC7) in the melting point between a 2-layer and a 1-layer crystal. There is also a large odd/even alternation in the melting point for the 2-layer crystals which is not observed for the 1-layer crystals. This odd /even effect persists for all stacked lamella. These results unambiguously establish that this odd/even effect is an effect of layer-to-layer stacking. These results indicate that 1-layer (unstacked) crystals of other lamellar crystals such as alkanes may not show an odd/even effect. Previous studies on alkanes have used multilayer stacked samples. A multi-variable phenomenological model for

  7. Bridging nanocontacts to macroscale gecko adhesion by sliding soft lamellar skin supported setal array.

    Science.gov (United States)

    Tian, Yu; Wan, Jin; Pesika, Noshir; Zhou, Ming

    2013-01-01

    The study of the mechanism of the controlled adhesion of geckos, which is important for the design and fabrication of bio-inspired dry and reversible adhesive surfaces, is widely discussed below the setal level. In this work, the role of the soft lamellar skin in gecko toe adhesion was experimentally revealed. The lamellar skin acting as a soft spring sustains most of the normal deformation during preloading and maintains a wide range of adhesive state rather than a repulsive state. The sequential engagement and peeling off of setal array are responsible for the reliable gecko adhesion and friction control. This soft spring supported pillar structure should be adopted in future bio-inspired adhesives design. A hybrid three-legged spring/setae clamp was developed to transfer a horizontally placed silicon wafer. It indicates the importance of integration and optimization of nanoscale structures as well as the incorporation of their unique, size-dependent properties into functional macroscale devices.

  8. A structurally diverse library of safe-by-design citrem-phospholipid lamellar and non-lamellar liquid crystalline nano-assemblies

    DEFF Research Database (Denmark)

    Mat Azmi, Intan Diana Binti; Wibroe, Peter Popp; Wu, Lin-Ping

    2016-01-01

    Non-lamellar liquid crystalline aqueous nanodispersions, known also as ISAsomes (internally self-assembled 'somes' or nanoparticles), are gaining increasing interest in drug solubilisation and bio-imaging, but they often exhibit poor hemocompatibility and induce cytotoxicity. This limits their ap......Non-lamellar liquid crystalline aqueous nanodispersions, known also as ISAsomes (internally self-assembled 'somes' or nanoparticles), are gaining increasing interest in drug solubilisation and bio-imaging, but they often exhibit poor hemocompatibility and induce cytotoxicity. This limits...... their applications in intravenous drug delivery and targeting. Using a binary mixture of citrem and soy phosphatidylcholine (SPC) at different weight ratios, we describe a library of colloidally stable aqueous and hemocompatible nanodispersions of diverse nanoarchitectures (internal self-assembled nanostructures......). This engineered library is structurally stable in human plasma as well as being hemocompatible (non-hemolytic, and poor activator of the complement system). By varying citrem to lipid weight ratio, the nanodispersion susceptibility to macrophage uptake could also be modulated. Finally, the formation...

  9. Hierarchical Formation of Fibrillar and Lamellar Self-Assemblies from Guanosine-Based Motifs

    Science.gov (United States)

    Neviani, Paolo; Sarazin, Dominique; Schmutz, Marc; Blanck, Christian; Giuseppone, Nicolas; Spada, Gian Piero

    2010-01-01

    Here we investigate the supramolecular polymerizations of two lipophilic guanosine derivatives in chloroform by light scattering technique and TEM experiments. The obtained data reveal the presence of several levels of organization due to the hierarchical self-assembly of the guanosine units in ribbons that in turn aggregate in fibrillar or lamellar soft structures. The elucidation of these structures furnishes an explanation to the physical behaviour of guanosine units which display organogelator properties. PMID:20798860

  10. Hierarchical Formation of Fibrillar and Lamellar Self-Assemblies from Guanosine-Based Motifs

    Directory of Open Access Journals (Sweden)

    Paolo Neviani

    2010-01-01

    Full Text Available Here we investigate the supramolecular polymerizations of two lipophilic guanosine derivatives in chloroform by light scattering technique and TEM experiments. The obtained data reveal the presence of several levels of organization due to the hierarchical self-assembly of the guanosine units in ribbons that in turn aggregate in fibrillar or lamellar soft structures. The elucidation of these structures furnishes an explanation to the physical behaviour of guanosine units which display organogelator properties.

  11. Common complications of deep lamellar keratoplasty in the early phase of the learning curve

    Directory of Open Access Journals (Sweden)

    Hosny M

    2011-06-01

    Full Text Available Mohamed HosnyOphthalmology Department, Faculty of Medicine, Cairo University, Cairo, EgyptPurpose: To evaluate and record the common complications that face surgeons when they perform their first few series of deep lamellar keratoplasty and measures to avoid these.Setting: Dar El Oyoun Hospital, Cairo, Egypt.Methods: Retrospective study of the first 40 eyes of 40 patients carried out by two corneal surgeons working in the same center. All patients were planned to undergo a deep anterior lamellar keratoplasty using the big bubble technique. Twelve patients suffered from keratoconus while 28 patients had anterior corneal pathologies. Recorded complications were classified as either intraoperative or postoperative.Results: Perforation of Descemet's membrane was the most common intraoperative complication. It occurred in nine eyes (22.5%: five eyes (12.5% had microperforations while four eyes (10% had macroperforations, three eyes (7.5% had central perforations, and six eyes (15% had peripheral perforations. Other complications included incomplete separation of Descemet's membrane and remnants of peripheral stromal tissue. Postoperative complications included double anterior chamber which occurred in four eyes (10% and Descemet's membrane corrugations. Postoperative astigmatism ranged from 1.25 to 4.5 diopters with a mean of 2.86 diopters in the whole series, but in the six cases with identified residual stroma in the periphery of the host bed, the astigmatism ranged from 2.75 to 4.5 diopters with a mean of 3.62 diopters.Conclusion: Deep lamellar keratoplasty is sensitive to procedural details. Learning the common complications and how to avoid them helps novice surgeons to learn the procedure faster.Keywords: deep lamellar keratoplasty, complications, big bubble technique

  12. Helicoidal multi-lamellar features of RGD-functionalized silk biomaterials for corneal tissue engineering

    OpenAIRE

    Gil, Eun Seok; Mandal, Biman B.; Park, Sang-Hyug; Marchant, Jeffrey K.; Omenetto, Fiorenzo G.; Kaplan, David L.

    2010-01-01

    RGD-coupled silk protein-biomaterial lamellar systems were prepared and studied with human cornea fibroblasts (hCFs) to match functional requirements. A strategy for corneal tissue engineering was pursued to replicate the structural hierarchy of human corneal stroma within thin stacks of lamellae-like tissues, in this case constructed from scaffolds constructed with RGD-coupled, patterned, porous, mechanically robust and transparent silk films. The influence of RGD-coupling on the orientation...

  13. Demonstration of cornea Dua's layer at a deep anterior lamellar keratoplasty surgery.

    Science.gov (United States)

    Koçluk, Yusuf; Burcu, Ayşe; Sukgen, Emine Alyamaç

    2016-01-01

    The authors aimed to present a deep anterior lamellar keratoplasty (DALK) surgery case with mixed type bubble demonstrating Dua's layer (DL). This was a reported case of DALK surgery. The authors encountered cornea DL structure at DALK surgery while cleaning the remaining stromal pieces. We also observed perforation in the central part of DL. However, DALK surgery could be completed. It is possible to encounter DL in a DALK surgery performed with mixed type big-bubble.

  14. Demonstration of cornea Dua's layer at a deep anterior lamellar keratoplasty surgery

    OpenAIRE

    Yusuf Kocluk; Ayse Burcu; Emine Alyamac Sukgen

    2016-01-01

    The authors aimed to present a deep anterior lamellar keratoplasty (DALK) surgery case with mixed type bubble demonstrating Dua′s layer (DL). This was a reported case of DALK surgery. The authors encountered cornea DL structure at DALK surgery while cleaning the remaining stromal pieces. We also observed perforation in the central part of DL. However, DALK surgery could be completed. It is possible to encounter DL in a DALK surgery performed with mixed type big-bubble.

  15. Milk Thistle Extract and Silymarin Inhibit Lipopolysaccharide Induced Lamellar Separation of Hoof Explants in Vitro

    Directory of Open Access Journals (Sweden)

    Nicole Reisinger

    2014-10-01

    Full Text Available The pathogenesis of laminitis is not completely identified and the role of endotoxins (lipopolysaccharides, LPS in this process remains unclear. Phytogenic substances, like milk thistle (MT and silymarin, are known for their anti-inflammatory and antioxidant properties and might therefore have the potential to counteract endotoxin induced effects on the hoof lamellar tissue. The aim of our study was to investigate the influence of endotoxins on lamellar tissue integrity and to test if MT and silymarin are capable of inhibiting LPS-induced effects in an in vitro/ex vivo model. In preliminary tests, LPS neutralization efficiency of these phytogenics was determined in an in vitro neutralization assay. Furthermore, tissue explants gained from hooves of slaughter horses were tested for lamellar separation after incubation with different concentrations of LPS. By combined incubation of explants with LPS and either Polymyxin B (PMB; positive control, MT or silymarin, the influence of these substances on LPS-induced effects was assessed. In the in vitro neutralization assay, MT and silymarin reduced LPS concentrations by 64% and 75%, respectively, in comparison PMB reduced 98% of the LPS concentration. In hoof explants, LPS led to a concentration dependent separation. Accordantly, separation force was significantly decreased by 10 µg/mL LPS. PMB, MT and silymarin could significantly improve tissue integrity of explants incubated with 10 µg/mL LPS. This study showed that LPS had a negative influence on the structure of hoof explants in vitro. MT and silymarin reduced endotoxin activity and inhibited LPS-induced effects on the lamellar tissue. Hence, MT and silymarin might be used to support the prevention of laminitis and should be further evaluated for this application.

  16. A case of acute postoperative keratitis after deep anterior lamellar keratoplasty by multidrug resistant Klebsiella

    Directory of Open Access Journals (Sweden)

    Leena Bajracharya

    2015-01-01

    Full Text Available A healthy lady of 42 years underwent deep anterior lamellar keratoplasty for granular dystrophy. The very next day, it was complicated by development of infectious keratitis. The organism was identified as multidrug resistant Klebsiella pneumoniae. Donor corneal button may be implicated in the transmission of infection in an otherwise uneventful surgery and follow-up. Nosocomial infections are usually severe, rapidly progressive and difficult to treat. Finally, the lady had to undergo therapeutic penetrating keratoplasty for complete resolution of infection.

  17. Mechanism for Formation of Lamellar Constituents in Grain-Refined Pd-Cu-Ga Dental Alloys

    OpenAIRE

    Brantley, William A.; Cai, Zhuo; Mitchell, John C.; Vermilyea, Stanley G.

    1997-01-01

    Grain-refined Pd-Cu-Ga dental alloys solidify with a lamellar microstructural constituent that affects a variety of clinically relevant properties. While formation of this constituent has been attributed to eutectic solidification, an alternative mechanism of discontinuous precipitation has been proposed. Using a representative grain-refined Pd-Cu-Ga dental alloy, casting procedures involving two different rates of solidification were used: (a) A standard thin-walled coping configuration for ...

  18. Surfactant films in lyotropic lamellar (and related) phases: Fluctuations and interactions.

    Science.gov (United States)

    Nallet, Frédéric

    2017-09-01

    The analogy between soap films thinning under border capillary suction and lamellar stacks of surfactant bilayers dehydrated by osmotic stress is explored, in particular in the highly dehydrated limit where the soap film becomes a Newton black film. The nature of short-range repulsive interactions between surfactant-covered interfaces and acting across water channels in both cases will be discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. In situ ultrahigh-resolution optical coherence tomography characterization of eye bank corneal tissue processed for lamellar keratoplasty.

    Science.gov (United States)

    Brown, Jamin S; Wang, Danling; Li, Xiaoli; Baluyot, Florence; Iliakis, Bernie; Lindquist, Thomas D; Shirakawa, Rika; Shen, Tueng T; Li, Xingde

    2008-08-01

    To use optical coherence tomography (OCT) as a noninvasive tool to perform in situ characterization of eye bank corneal tissue processed for lamellar keratoplasty. A custom-built ultrahigh-resolution OCT (UHR-OCT) was used to characterize donor corneal tissue that had been processed for lamellar keratoplasty. Twenty-seven donor corneas were analyzed. Four donor corneas were used as controls, whereas the rest were processed into donor corneal buttons for lamellar transplantation by using hand dissection, a microkeratome, or a femtosecond laser. UHR-OCT was also used to noninvasively characterize and monitor the viable corneal tissue immersed in storage medium over 3 weeks. The UHR-OCT captured high-resolution images of the donor corneal tissue in situ. This noninvasive technique showed the changes in donor corneal tissue morphology with time while in storage medium. The characteristics of the lamellar corneal tissue with each processing modality were clearly visible by UHR-OCT. The in situ characterization of the femtosecond laser-cut corneal tissue was noted to have more interface debris than shown by routine histology. The effects of the femtosecond laser microcavitation bubbles on the corneal tissue were well visualized at the edges of the lamellar flap while in storage medium. The results of our feasibility study show that UHR-OCT can provide superb, in situ microstructural characterization of eye bank corneal tissue noninvasively. The UHR-OCT interface findings and corneal endothelial disc thickness uniformity analysis are valuable information that may be used to optimize the modalities and parameters for lamellar tissue processing. The UHR-OCT is a powerful approach that will allow us to further evaluate the tissue response to different processing techniques for posterior lamellar keratoplasty. It may also provide information that can be used to correlate with postoperative clinical outcomes. UHR-OCT has the potential to become a routine part of tissue

  20. A numerical model for the description of the lamellar and massive phase transformations in TiAl alloys

    OpenAIRE

    A. Rostamian; Jacot, A.

    2008-01-01

    A phenomenological modelling approach has been developed to describe the massive transformation and the formation of lamellar microstructures during cooling in binary gamma titanium aluminides. The modelling approach is based on a combination of nucleation and growth laws which take into account the specific mechanisms of each phase transformation. Nucleation of massive and lamellar gamma is described with classical nucleation theory, accounting for the fact that nuclei are formed predominant...

  1. Microkeratome-assisted superficial anterior lamellar keratoplasty for anterior stromal corneal opacities after penetrating keratoplasty.

    Science.gov (United States)

    Patel, Amit K; Scorcia, Vincenzo; Kadyan, Anju; Lapenna, Lucia; Ponzin, Diego; Busin, Massimo

    2012-01-01

    To describe the surgical technique and report the outcomes of patients treated with microkeratome-assisted superficial anterior lamellar keratoplasty for anterior stromal corneal opacities developing after penetrating keratoplasty (PK). All patients with post-penetrating keratoplasty anterior stromal opacities treated with microkeratome-assisted superficial anterior lamellar keratoplasty between July 2005 and June 2007 were reviewed. A 130-μm superficial keratectomy was performed, followed by the placement of an appropriately sized donor graft, which was secured with overlay sutures. Refraction, corneal topography, and uncorrected and best-corrected visual acuities (UCVA, BCVA, respectively) were noted at each examination. Nine eyes of 8 consecutive patients were identified. Causes of anterior stromal opacities included dystrophy recurrence (n = 3), post-photorefractive keratectomy haze (n = 2), and scarring after stromal melt (n = 4). BCVA improved in all 9 eyes at final follow-up, and 7 of 9 eyes achieved ≥20/40 within the first month. Average follow-up period was 28 ± 3.9 months. Refractive astigmatism also improved by an average of 0.7 diopters. Superficial anterior lamellar keratoplasty is a viable and effective alternative to repeat PK in treating anterior stromal scars. It avoids open-globe surgery and exposure to endothelial rejection associated with repeat PK, and visual rehabilitation is considerably quicker.

  2. Structure and formation of the twisted plywood pattern of collagen fibrils in rat lamellar bone.

    Science.gov (United States)

    Yamamoto, Tsuneyuki; Hasegawa, Tomoka; Sasaki, Muneteru; Hongo, Hiromi; Tabata, Chihiro; Liu, Zhusheng; Li, Minqi; Amizuka, Norio

    2012-04-01

    This study was designed to elucidate details of the structure and formation process of the alternate lamellar pattern known to exist in lamellar bone. For this purpose, we examined basic internal lamellae in femurs of young rats by transmission and scanning electron microscopy, the latter employing two different macerations with NaOH at concentrations of 10 and 24%. Observations after the maceration with 10% NaOH showed that the regular and periodic rotation of collagen fibrils caused an alternation between two types of lamellae: one consisting of transversely and nearly transversely cut fibrils, and the other consisting of longitudinally and nearly longitudinally cut fibrils. This finding confirms the consistency of the twisted plywood model. The maceration method with 24% NaOH removed bone components other than cells, thus allowing for three-dimensional observations of osteoblast morphology. Osteoblasts extended finger-like processes paralleling the inner bone surface, and grouped in such a way that, within a group, the processes arranged in a similar direction. Transmission electron microscopy showed that newly deposited fibrils were arranged alongside these processes. For the formation of the alternating pattern, our findings suggest that: (1) osteoblasts control the collagen fibril arrangement through their finger-like process position; (2) osteoblasts behave similarly within a group; (3) osteoblasts move their processes synchronously and periodically to promote alternating different fibril orientation; and (4) this dynamic sequential deposition of fibrils results in the alternate lamellar (or twisted plywood) pattern.

  3. Lamellar structures and bacteria as main components of the amorphous matter of source rocks

    Energy Technology Data Exchange (ETDEWEB)

    Raynaud, J.F.; Lacrampe-Couloume, G. (Societe Nationale Elf-Aquitaine, 64 - Pau (FR). Lab. de Geologie); Lugardon, B. (Toulouse-3 Univ., 31 (FR). Lab. de Biologie Vegetale)

    1989-01-01

    Kerogen of most marine and lacustrine petroleum source rocks is optically composed of amorphous organic matter devoid of any mark of nature or origin. Analysis of this organic matter with a transmission electron microscope shows many structures of obviously biological origin, the most prominent of which are lamellar membranes, frequently associated with groups of bacteria-like bodies. Lamellar structures could correspond either to cellular membranes issued from phytoplankton which are strengthened by rigidifying agents (hopanetetrols and sterols), or to cell-walls composed of insoluble acid-resistant biopolymers. Such cell-walls have already been observed in blue and green algae but very exceptionally in extent phytoplanktonic algae such as dinoflagellates, diatoms and coccolithophorids. Whatever these lamellar structures could be, these observations show that amorphous kerogens of aquatic petroleum source rocks result essentially from accumulation of organic structures directly inherited from phytoplankton. So the former geochemical theories, abiological (polycondensation of dispersed organic particles or polymerization of monomers), or biological (complete bacterial reworking), must be reinterpreted in the light of these new data. 6 plates.

  4. Helicoidal multi-lamellar features of RGD-functionalized silk biomaterials for corneal tissue engineering.

    Science.gov (United States)

    Gil, Eun Seok; Mandal, Biman B; Park, Sang-Hyug; Marchant, Jeffrey K; Omenetto, Fiorenzo G; Kaplan, David L

    2010-12-01

    RGD-coupled silk protein-biomaterial lamellar systems were prepared and studied with human cornea fibroblasts (hCFs) to match functional requirements. A strategy for corneal tissue engineering was pursued to replicate the structural hierarchy of human corneal stroma within thin stacks of lamellae-like tissues, in this case constructed from scaffolds constructed with RGD-coupled, patterned, porous, mechanically robust and transparent silk films. The influence of RGD-coupling on the orientation, proliferation, ECM organization, and gene expression of hCFs was assessed. RGD surface modification enhanced cell attachment, proliferation, alignment and expression of both collagens (type I and V) and proteoglycans (decorin and biglycan). Confocal and histological images of the lamellar systems revealed that the bio-functionalized silk human cornea 3D constructs exhibited integrated corneal stroma tissue with helicoidal multi-lamellar alignment of collagen-rich and proteoglycan-rich extracellular matrix, with transparency of the construct. This biomimetic approach to replicate corneal stromal tissue structural hierarchy and architecture demonstrates a useful strategy for engineering human cornea. Further, this approach can be exploited for other tissue systems due to the pervasive nature of such helicoids in most human tissues. Copyright © 2010 Elsevier Ltd. All rights reserved.

  5. Reverse osmosis desalination of chitosan cross-linked graphene oxide/titania hybrid lamellar membranes.

    Science.gov (United States)

    Deng, Hui; Sun, Penzhan; Zhang, Yingjiu; Zhu, Hongwei

    2016-07-08

    With excellent mass transport properties, graphene oxide (GO)-based lamellar membranes are believed to have great potential in water desalination. In order to quantify whether GO-based membranes are indeed suitable for reverse osmosis (RO) desalination, three sub-micrometer thick GO-based lamellar membranes: GO-only, reduced GO (RGO)/titania (TO) nanosheets and RGO/TO/chitosan (CTS) are prepared, and their RO desalination performances are evaluated in a home-made RO test apparatus. The photoreduction of GO by TO improves the salt rejection, which increases slowly with the membrane thickness. The RGO/TO/CTS hybrid membranes exhibit higher rejection rates of only about 30% (greater than threefold improvement compared with a GO-only membrane) which is still inferior compared to other commercial RO membranes. The low rejection rates mainly arise from the pressure-induced weakening of the ion-GO interlayer interactions. Despite the advantages of simple, low-cost preparation, high permeability and selectivity of GO-based lamellar membranes, as the current desalination performances are not high enough to afford practical application, there still remains a great challenge to realize high performance separation membranes for water desalination applications.

  6. A structural study of lamellar phases formed by nucleoside-functionalized lipids

    CERN Document Server

    Berti, D; Baglioni, P; Dante, S; Hauss, T

    2002-01-01

    We report a neutron-scattering investigation of lamellar phases formed by novel phospholipids bearing nucleosides at the polar-head-group region. These nucleolipids can interact through stacking and H-bond interactions, following a pattern that resembles base-base coupling in natural nucleic acids (DNA, RNA), i.e. they have similar recognition properties. Bilayer stacks formed of DPP-adenosine, DPP-uridine and their 1:1 mixture were investigated after equilibration in a 98% relative humidity atmosphere. The DPP-adenosine spectrum can be accounted for (in analogy to DPPC) by a lamellar phase with a smectic period of about 60 A. DPP-uridine displays a not so straightforward behavior that we have tentatively ascribed to the coexistence of lamellae with different smectic periods. In the 1:1 mixture the lamellar mesophase of DPP-uridine is retained, suggesting a specific interaction of the uridine polar-head group with the adenosine moiety of DPP-adenosine. It should be stressed that this behavior can be considere...

  7. Macular electroretinograms to flicker and pattern stimulation in lamellar macular holes.

    Science.gov (United States)

    Falsini, B; Minnella, A; Buzzonetti, L; Merendino, E; Porciatti, V

    1992-01-01

    Steady-state macular (9 degrees x 9 degrees) electroretinograms in response to either sinusoidal flicker (focal electroretinogram) or counterphased sinusoidal gratings (pattern electroretinogram) were recorded in 14 patients with inner lamellar macular holes, in 4 patients with full-thickness macular holes and in 14 age-matched controls. Fourier analysis of focal and pattern electroretinograms yielded three main components: a first and a second harmonic to flicker, and a second harmonic to pattern. Recent evidence indicates that the first harmonic to flicker is of receptoral origin, whereas the flicker and pattern second harmonics represent, at least in part, the activity of different generators in the inner retina. When compared to controls, patients with inner lamellar holes showed significant amplitude reduction and phase delay for both flicker and pattern second harmonics, but not for the flicker first harmonic. Patients with full-thickness holes showed significant amplitude reduction also for the flicker first harmonic. These results indicate a prevalent functional involvement of the inner retina in lamellar macular holes, which can be clinically detected by evaluating focal and pattern electroretinogram second harmonics.

  8. One-step exfoliation and surface modification of lamellar hydroxyapatite by intercalation of glucosamine

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Honglin [Research Institute for Biomaterials and Transportation, East China Jiaotong University, Nanchang, 330013 (China); School of Materials Science and Engineering, Tianjin University, Tianjin, 300072 (China); Li, Wei; Ji, Dehui [Research Institute for Biomaterials and Transportation, East China Jiaotong University, Nanchang, 330013 (China); Zuo, Guifu [Hebei Provincial Key Laboratory of Inorganic Nonmetallic Materials, College of Materials Science and Engineering, Hebei United University, Tangshan, 063009 (China); Xiong, Guangyao, E-mail: xiongguangyao@163.com [Research Institute for Biomaterials and Transportation, East China Jiaotong University, Nanchang, 330013 (China); Zhu, Yong [School of Chemical Engineering, Tianjin University, Tianjin, 300072 (China); Li, Lili; Han, Ming [Research Institute for Biomaterials and Transportation, East China Jiaotong University, Nanchang, 330013 (China); Wu, Caoqun [School of Materials Science and Engineering, Tianjin University, Tianjin, 300072 (China); Wan, Yizao, E-mail: yzwantju@126.com [Research Institute for Biomaterials and Transportation, East China Jiaotong University, Nanchang, 330013 (China); School of Materials Science and Engineering, Tianjin University, Tianjin, 300072 (China)

    2016-04-15

    Effective exfoliation is crucial to the application of layered materials in many fields. Herein, we report a novel effective, scalable, and ecofriendly method for the exfoliation of lamellar HAp by glucosamine intercalation such that individual HAp nanoplates can be obtained. The as-exfoliated HAp nanoplates were characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and thermogravimetric (TG) analysis. It is found that the glucosamine intercalation not only results in complete exfoliation of lamellar HAp but also introduces the glucosamine molecules onto the surface of individual HAp nanoplates, thus obtaining separated glucosamine-grafted HAp nanoplates (Glu-HAps). Results from MTT assay demonstrate that glucosamine grafting on HAp nanoplates greatly improves the cell growth and proliferation as compared to nongrafted HAp counterparts. - Highlights: • Glucosamine was used as intercalation agent to exfoliate lamellar hydroxyapatite. • Glucosamine was grafted onto the as-exfoliated nanoplate-like hydroxyapatite. • Exfoliation and surface grafting were accomplished in one step. • Glucosamine-grafted HAp showed improved biocompatibility over nongrafted one.

  9. Histological review of the human cellular cementum with special reference to an alternating lamellar pattern.

    Science.gov (United States)

    Yamamoto, Tsuneyuki; Li, Minqi; Liu, Zhucheng; Guo, Ying; Hasegawa, Tomoka; Masuki, Hideo; Suzuki, Reiko; Amizuka, Norio

    2010-07-01

    Cementum is mineralized tissue with collagen fibrils as its major organic component, and it can be roughly classified into acellular and cellular cementum. The latter generally consists of a stack of cellular intrinsic fiber cementum layers, in which intensely and weakly stained lamellae (each about 2.5 microm thick) alternate in light microscopic observations. It has been suggested that the alternate lamellar pattern results from periodic changes of the intrinsic fiber arrangement, but owing to the difficulty of observing the fibril arrangement three dimensionally, details were not understood until recently. The NaOH-maceration method has been developed to overcome this difficulty. For the past two decades, we have studied the structure and development of cementum by scanning electron microscopy using NaOH-maceration, as well as by light and transmission electron microscopy, and have accumulated a significant amount of data with regard to the structure and formation of cementum. In light of these data, we have arrived at the following conclusions: (1) The alternate lamellar pattern conforms to the twisted plywood model, in which collagen fibrils rotate regularly in the same direction to form two alternating types of lamellae; one type consists of transversely and almost transversely cut fibrils and the other consists of longitudinally and almost longitudinally cut fibrils. (2) The development of the intrinsic fiber arrangement may be controlled by cementoblasts; the cementoblasts move finger-like processes synchronously and periodically to create alternate changes in the intrinsic fiber arrangement, and this dynamic sequence results in the alternate lamellar pattern.

  10. Reverse osmosis desalination of chitosan cross-linked graphene oxide/titania hybrid lamellar membranes

    Science.gov (United States)

    Deng, Hui; Sun, Penzhan; Zhang, Yingjiu; Zhu, Hongwei

    2016-07-01

    With excellent mass transport properties, graphene oxide (GO)-based lamellar membranes are believed to have great potential in water desalination. In order to quantify whether GO-based membranes are indeed suitable for reverse osmosis (RO) desalination, three sub-micrometer thick GO-based lamellar membranes: GO-only, reduced GO (RGO)/titania (TO) nanosheets and RGO/TO/chitosan (CTS) are prepared, and their RO desalination performances are evaluated in a home-made RO test apparatus. The photoreduction of GO by TO improves the salt rejection, which increases slowly with the membrane thickness. The RGO/TO/CTS hybrid membranes exhibit higher rejection rates of only about 30% (greater than threefold improvement compared with a GO-only membrane) which is still inferior compared to other commercial RO membranes. The low rejection rates mainly arise from the pressure-induced weakening of the ion-GO interlayer interactions. Despite the advantages of simple, low-cost preparation, high permeability and selectivity of GO-based lamellar membranes, as the current desalination performances are not high enough to afford practical application, there still remains a great challenge to realize high performance separation membranes for water desalination applications.

  11. Oligosaccharides and glycolipids addition in charged lamellar phases; Addition d`oligosaccharides et de glycolipides dans des phases lamellaires chargees

    Energy Technology Data Exchange (ETDEWEB)

    Ricoul, F

    1997-09-26

    The aim of this work is to study the addition of oligosaccharides and glycolipids in lamellar phases of the cationic surfactant DDAB (di-dodecyl-dimethyl-ammonium bromide). Two steps have been followed: the determination of phases prisms and the thermodynamic interpretation in terms of molecular interactions. In order to characterize these systems, two new experimental small angle scattering methods have been perfected: 1) a neutron scattering contrast variation method which allows to study the adsorption of aqueous solution in bilayers and 2) a capillary concentration gradient method to establish directly and quantitatively the phases diagrams of ternary systems by X rays scattering. It has been pointed out that the oligosaccharides induce a depletion attractive force on the lamellar-lamellar equilibrium of the DDAB when they are excluded of the most concentrated phase. For the two studied glycolipids: 2-O lauroyl-saccharose and N-lauroyl N-nonyl lactitol, the ternary phase diagrams water-DDAB-glycolipid have been established in terms of temperature. Critical points at ambient temperature have been given. The osmotic pressure in concentrated lamellar phases has been measured. It has been shown that glycolipids increase the hydration repulsion at short distance and that the electrostatic repulsion is outstanding and unchanged at high distance if there is at less 1 mole percent of ionic surfactant. In a dilute solution, glycolipids decrease the maximum swelling of lamellar phases, with a competition between the lamellar phase and the micellae dilute phase for water. (O.M.). 165 refs.

  12. Liquid crystalline phases of dendritic lipid-DNA self-assemblies: lamellar, hexagonal, and DNA bundles.

    Science.gov (United States)

    Zidovska, Alexandra; Evans, Heather M; Ewert, Kai K; Quispe, Joel; Carragher, Bridget; Potter, Clinton S; Safinya, Cyrus R

    2009-03-26

    The prospects of gene therapy have generated unprecedented interest in the properties and structures of complexes of nucleic acids (NAs) with cationic liposomes (CLs), which are used as nonviral NA carriers in worldwide clinical trials. An improved understanding of the mechanisms of action of CL-NA complexes is required to enable their widespread therapeutic use. In prior studies of CL-mediated DNA delivery, membrane charge density (sigma(M)) was identified as a key parameter for transfection efficiency (TE) of lamellar (L(alpha)(C)) CL-DNA complexes. The TE of CL-DNA complexes containing cationic lipids with headgroup valencies from 1+ to 5+ follows a universal bell-shaped curve as a function of sigma(M). As we report here, the TE of CL-DNA complexes containing new multivalent lipids with dendritic headgroups (DLs) strongly deviates from this curve at high sigma(M). We have investigated four DLs, MVLG2 (4+), MVLG3 (8+), MVLBisG1 (8+), and MVLBisG2 (16+), in mixtures with neutral 1,2-dioleoyl-sn-glycerophosphatidyl-choline (DOPC). To understand the TE behavior, we have performed X-ray diffraction (XRD), optical microscopy, and cryo-TEM studies of the DL/DOPC mixtures and their DNA complexes. XRD reveals a complex phase behavior of DL-DNA complexes which strongly depends on the headgroup charge. MVLG2(4+)/DOPC-DNA complexes exhibit the lamellar phase at all molar fractions of DL, Phi(DL). In stark contrast, MVLBisG2(16+)/ DOPC-DNA complexes remain lamellar only for Phi(DL) phase H(I)(C), consisting of a hexagonal lattice of cylindrical lipid micelles and a DNA honeycomb lattice, is formed. At Phi(DL) > 0.3, XRD suggests formation of a distorted H(I)(C) phase. For Phi(DL) > or = 0.5 under high salt conditions, this phase coexists with a bundle phase of DNA condensed by the depletion-attraction effect of DL micelles. The transitions at high sigma(M) from the lamellar phase to the new hexagonal phases of DL-DNA complexes coincide with the deviation from the universal

  13. Crystal structure, thermal behavior and enzymatic degradation of poly(tetramethylene adipate) solution-grown chain-folded lamellar crystals.

    Science.gov (United States)

    Iwata, Tadahisa; Kobayashi, Shiomi; Tabata, Kenji; Yonezawa, Noriyuki; Doi, Yoshiharu

    2004-03-15

    Solution-grown chain-folded lamellar single crystals of poly(tetramethylene adipate) (PTMA) were prepared from a dilute solution of 2-methyl-1-propanol by isothermal crystallization. PTMA crystals were hexagonal-shaped and polyethylene decoration of the crystals resulted in a "six cross-sector" surface morphology and showed that the average direction of chain folding is parallel to the crystal growth planes of [110] and [010]. Chain-folded lamellar crystals gave well-resolved electron diffraction diagrams corresponding to all the equatorial reflections of the X-ray fiber diagram obtained from stretched PTMA melt-quenched film (beta structure). The unit cell parameters of the beta structure of PTMA were determined as a = 0.503 nm, b = 0.732 nm and c (fiber axis) = 1.442 nm with an orthorhombic crystal system. The fiber repeat distance is appropriate for an all-trans backbone conformation for the straight stems. The setting angle, with respect to the a axis, is +/-46 degrees for the corner and center chains. Thermal behavior of lamellar crystals has been investigated by means of transmission electron microscopy (TEM) and atomic force microscopy (AFM). The lamellar thickness at the edges of the crystal increased after thermal treatment with taking the molecular chains into recrystallization parts; the holes then opened up at the thickening front of the crystal. The morphological changes of lamellar crystals after enzymatic degradation by Lipase type XIII from Pseudomonas sp. and water-soluble products were characterized by TEM, AFM, gel permeation chromatography, high performance liquid chromatography and fast atom bombardment mass spectrometry. The degradation progressed mainly from the edges of the lamellar crystals without decreasing the molecular weights and the lamellar thicknesses. The central portion of single crystals was often degraded by enzymatic attacks. This result combined with thermal behavior indicates that the loosely chain-packing region exists

  14. Transformer core

    NARCIS (Netherlands)

    Mehendale, A.; Hagedoorn, Wouter; Lötters, Joost Conrad

    2008-01-01

    A transformer core includes a stack of a plurality of planar core plates of a magnetically permeable material, which plates each consist of a first and a second sub-part that together enclose at least one opening. The sub-parts can be fitted together via contact faces that are located on either side

  15. Transformer core

    NARCIS (Netherlands)

    Mehendale, A.; Hagedoorn, Wouter; Lötters, Joost Conrad

    2010-01-01

    A transformer core includes a stack of a plurality of planar core plates of a magnetically permeable material, which plates each consist of a first and a second sub-part that together enclose at least one opening. The sub-parts can be fitted together via contact faces that are located on either side

  16. Repair of articular osteochondral defects of the knee joint using a composite lamellar scaffold.

    Science.gov (United States)

    Lv, Y M; Yu, Q S

    2015-04-01

    The major problem with repair of an articular cartilage injury is the extensive difference in the structure and function of regenerated, compared with normal cartilage. Our work investigates the feasibility of repairing articular osteochondral defects in the canine knee joint using a composite lamellar scaffold of nano-ß-tricalcium phosphate (ß-TCP)/collagen (col) I and II with bone marrow stromal stem cells (BMSCs) and assesses its biological compatibility. The bone-cartilage scaffold was prepared as a laminated composite, using hydroxyapatite nanoparticles (nano-HAP)/collagen I/copolymer of polylactic acid-hydroxyacetic acid as the bony scaffold, and sodium hyaluronate/poly(lactic-co-glycolic acid) as the cartilaginous scaffold. Ten-to 12-month-old hybrid canines were randomly divided into an experimental group and a control group. BMSCs were obtained from the iliac crest of each animal, and only those of the third generation were used in experiments. An articular osteochondral defect was created in the right knee of dogs in both groups. Those in the experimental group were treated by implanting the composites consisting of the lamellar scaffold of ß-TCP/col I/col II/BMSCs. Those in the control group were left untreated. After 12 weeks of implantation, defects in the experimental group were filled with white semi-translucent tissue, protruding slightly over the peripheral cartilage surface. After 24 weeks, the defect space in the experimental group was filled with new cartilage tissues, finely integrated into surrounding normal cartilage. The lamellar scaffold of ß-TCP/col I/col II was gradually degraded and absorbed, while new cartilage tissue formed. In the control group, the defects were not repaired. This method can be used as a suitable scaffold material for the tissue-engineered repair of articular cartilage defects. Cite this article: Bone Joint Res 2015;4:56-64. ©2015 The British Editorial Society of Bone & Joint Surgery.

  17. Femtosecond laser-assisted sutureless anterior lamellar keratoplasty for superficial corneal opacities.

    Science.gov (United States)

    Jabbarvand, Mahmoud; Hashemian, Hesam; Khodaparast, Mehdi; Ghadimi, Hadi; Khalilipour, Elias

    2014-11-01

    To evaluate the visual and refractive outcomes, endothelial cell count (ECC), ocular surface changes, corneal aberrations, and biomechanical profile changes after femtosecond laser-assisted anterior lamellar keratoplasty surgery for superficial corneal scars. Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran. Prospective case series. Patients with superficial corneal scars had femtosecond laser-assisted anterior lamellar keratoplasty. Visual and refractive results, ECC, ocular surface changes, corneal aberrations, and biomechanical profiles were assessed preoperatively and for 1 year postoperatively. Nineteen eyes (19 patients) were evaluated. A significant decline occurred in refractive astigmatism and corneal astigmatism after 1 year. There was a nonsignificant reduction in corneal hysteresis and the corneal resistance factor from preoperatively to 1 year postoperatively. The corneal-compensated intraocular pressure (IOP) and Goldmann-correlated IOP increased during the follow-up; the increase was not significant. A statistically insignificant reduction in the root mean square for trefoil and spherical aberrations occurred between 1 month and 1 year postoperatively (P=.1 and P=.4, respectively). The decreases in primary coma and total higher-order aberrations approached significance (P=.08 and P=.07, respectively). There were no significant changes in the central corneal thickness, ECC, or ocular surface parameters. No intraoperative complications occurred. Femtosecond laser-assisted anterior lamellar keratoplasty was an efficient and safe procedure for improving the quality of vision in patients with anterior corneal pathology, and the results remained stable during the 1-year follow-up. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  18. Aberrant lamellar body counts noted on the Beckman Coulter Unicel DxH 800.

    Science.gov (United States)

    Kyle, Patrick B; Lawrence, Thomas J

    2012-03-09

    The lamellar body count (LBC) plays a crucial role in fetal lung maturity testing. Lamellar bodies are often counted in the platelet channel of routine hematology analyzers, resulting in a rapid and inexpensive assay for fetal lung maturity. Recently, significant imprecision was noted during LBC validation on the Beckman Coulter Unicel DxH 800. The results of two Beckman Coulter Unicel DxH 800 instruments were compared to those of a Coulter LH 750 and Coulter LH 500. Three pools of amniotic fluid, commercial quality control materials, and proficiency test specimens were analyzed on all four instruments. Fifty patient specimens were also analyzed using the Coulter LH 500 and the Unicel DxH 800. The mean values and precision obtained from commercial quality control materials and proficiency test samples were comparable on all four instruments. However, many erroneously low LBC results were produced from amniotic fluid pools using both DxH 800 instruments. The erroneous values were approximately 50% lower than respective target values, occurred randomly, and affected the low, medium, and high LBC results. Inter-assay precision of the three pools ranged from 24.7 to 39.0 CV% on the DxH 800 instruments. The source of LBC errors likely involves the exclusion of smaller lamellar bodies from the counts. The DxH 800 combines new data fusion technology and mathematical algorithms to produce increased accuracy and flagging efficiency. Laboratorians should be aware that the improved specificity of the DxH 800 may preclude its use for this laboratory-developed test.

  19. The Big-Bubble Full Femtosecond Laser-Assisted Technique in Deep Anterior Lamellar Keratoplasty.

    Science.gov (United States)

    Buzzonetti, Luca; Petrocelli, Gianni; Valente, Paola; Iarossi, Giancarlo; Ardia, Roberta; Petroni, Sergio; Parrilla, Rosa

    2015-12-01

    To describe the big-bubble full femtosecond laser-assisted (BBFF) technique, which could be helpful in standardizing the big-bubble technique in deep anterior lamellar keratoplasty (DALK). Ten eyes of 10 consecutive patients affected by keratoconus underwent the BBFF technique using the 150-kHz IntraLase femtosecond laser (Intra-Lase FS Laser; Abbott Medical Optics, Inc., Santa Ana, CA). A 9-mm diameter metal mask with a single fissure 0.7 mm wide oriented at the 12-o'clock position was positioned into the cone, over the laser glass. The laser performed a ring lamellar cut (internal diameter = 3 mm; external diameter = 8 mm) 100 µm above the thinnest point, with the photodisruption effectively occurring only in the corneal stroma corresponding to the fissure to create a deep stromal channel; subsequently, an anterior side cut created an arcuate incision, from the corneal surface to the deep stromal channel on the mask's opening site. The mask was removed and the laser performed a full lamellar cut 200 µm above the thinnest point to create a lamella. After the removal of the lamella, the air needle was inserted into the stromal channel and air was injected to achieve a big bubble. The big bubble was achieved in 9 eyes (all type 1 bubbles) and all procedures were completed as DALK. Preliminary results suggest that the BBFF technique could help in standardizing the big-bubble technique in DALK, reducing the "learning curve" for surgeons who approach this technique and the risks of intraoperative complications. Copyright 2015, SLACK Incorporated.

  20. Comparison of synthetic glues and 10-0 nylon in rabbit lamellar keratoplasty.

    Science.gov (United States)

    Cho, Soon Young; Kim, Man Soo; Oh, Su Ja; Chung, Sung Kun

    2013-09-01

    To evaluate changes in mean keratometry and to compare wound repair with corneal lamellar grafts in rabbit eyes using human synthetic tissue adhesives and 10-0 nylon. Corneal grafts were made using a 6.0-mm-diameter trephine and blades in the eyes of 15 New Zealand white rabbits. Human fibrin tissue adhesive (Tisseel) was used in group 1, human fibrin tissue adhesive (Beriplast P) was used in group 2, polyethylene glycol adhesive (Coseal) was used in group 3, and 8 bite sutures with 10-0 nylon were used in group 4 (control) for lamellar keratoplasty. Four bite sutures were made with 10-0 nylon in groups 1, 2, and 3. Slit-lamp microscopy and keratometry were performed at 3 days and 1, 2, and 4 weeks after the surgery. Histopathologic and electromicroscopic examinations were performed 4 weeks after the surgery. No inflammation or corneal toxicity was seen in groups 1 and 2. Histologically, a few inflammatory cells were seen in groups 3 and 4. Groups 1, 2, and 3 showed no statistically significant changes in mean keratometry at 4 weeks postoperatively compared with preoperative mean keratometry (Wilcoxon signed-rank test, P = 0.178, 0.208, and 0.889, respectively). The control group showed significant changes in mean keratometry at 4 weeks postoperatively (Wilcoxon signed-rank test, P = 0.018). Human fibrin tissue adhesives were well tolerated in rabbit eyes, with no apparent corneal toxicity. Polyethylene glycol adhesive showed more inflammation and insufficient wound repair compared with human fibrin tissue adhesives. Therefore, human fibrin tissue adhesives can be used as an alternative to sutures in lamellar keratoplasty.

  1. GPHR-dependent functions of the Golgi apparatus are essential for the formation of lamellar granules and the skin barrier.

    Science.gov (United States)

    Tarutani, Masahito; Nakajima, Kimiko; Uchida, Yoshikazu; Takaishi, Mikiro; Goto-Inoue, Naoko; Ikawa, Masahito; Setou, Mitsutoshi; Kinoshita, Taroh; Elias, Peter M; Sano, Shigetoshi; Maeda, Yusuke

    2012-08-01

    The lumen of the Golgi apparatus is regulated to be weakly acidic, which is critical for its functions. The Golgi pH regulator (GPHR) is an anion channel essential for normal acidification of the Golgi apparatus, and is therefore required for its functions. The Golgi apparatus has been thought to be the origin of lamellar granules in the skin. To study the functional role(s) of GPHR in the skin, we established keratinocyte-specific GPHR-knockout mice using the Cre-loxP system. These mutant mice exhibited hypopigmented skin, hair loss, and scaliness. Histological examination of GPHR-knockout mice showed ballooning of the basal cells and follicular dysplasia. In addition, inflammatory cells were seen in the dermis. The expression of trans-Golgi network 46, a marker for lamellar bodies, and kallikrein 7, a protein within lamellar bodies, is diminished in GPHR-knockout mouse skin. Examination by electron microscopy revealed that keratinocytes produced aberrant lamellar bodies. The transepidermal water loss of these knockout mice was increased compared with wild-type mice. Moreover, expression of cathelicidin-related antimicrobial peptide (CRAMP) in the skin was diminished. These results suggest that GPHR is essential for the homeostasis of the epidermis including the formation of lamellar bodies and for the barrier function.

  2. Lamellar slippage of bilayers--a hypothesis on low friction of natural joints.

    Science.gov (United States)

    Pawlak, Zenon; Urbaniak, Wieslaw; Hagner-Derengowska, Magda; Hagner, Wojciech

    2014-12-01

    The cartilage's amphoteric surface behavior is a physical phenomenon in biological lubrication. However, there is a lack of knowledge on amphoteric phospholipids bilayers and in overcoming friction in cartilage joints. In this paper, friction experiments were conducted, and the cartilage's surface was characterized using pH and wettability, while the interfacial energy and coefficients were determined. The lamellar slippage of bilayers and a short-range repulsion between the interfaces of negatively charged (-PO4 (-)) cartilage surfaces resulted in low frictional properties of the joint.

  3. Fast Diffusion of Long Guest Rods in a Lamellar Phase of Short Host Particles

    Science.gov (United States)

    Alvarez, Laura; Lettinga, M. Paul; Grelet, Eric

    2017-04-01

    We investigate the dynamic behavior of long guest rodlike particles immersed in liquid crystalline phases formed by shorter host rods, tracking both guest and host particles by fluorescence microscopy. Counterintuitively, we evidence that long rods diffuse faster than short rods forming the one-dimensional ordered smectic-A phase. This results from the larger and noncommensurate size of the guest particles as compared to the wavelength of the energy landscape set by the lamellar stack of liquid slabs. The long guest particles are also shown to be still mobile in the crystalline smectic-B phase, as they generate their own voids in the adjacent layers.

  4. A lamellar model for the X-ray rocking curves of sagittally bent Laue crystals.

    Science.gov (United States)

    Zhong, Z; Kao, C C; Siddons, D P; Zhong, H; Hastings, J B

    2003-01-01

    The use of sagittally bent asymmetric Laue crystals in horizontally focusing monochromators for high-energy synchrotron X-rays necessitates simulation of the X-ray reflectivity by such crystals. Based on the theory of the lattice distortion in the diffraction plane of sagittally bent Laue crystals, a lamellar model was developed to predict their rocking curves. The model was experimentally verified by rocking-curve measurements from various reflections on silicon crystals of four representative orientations, sagittally bent to various radii, using X-rays of 67 keV energy.

  5. Use of trypan blue dye during conversion of deep anterior lamellar keratoplasty to penetrating keratoplasty.

    Science.gov (United States)

    Sharma, Namrata; Jhanji, Vishal; Titiyal, Jeewan S; Amiel, Howard; Vajpayee, Rasik B

    2008-08-01

    We describe a technique that uses trypan blue dye to identify residual recipient corneal stroma and Descemet membrane (DM) during conversion of deep anterior lamellar keratoplasty (DALK) to penetrating keratoplasty (PKP). After the host cornea is dissected, trypan blue dye (0.06%) is used to highlight the remaining host corneal stroma and DM, if any. In 8 DALK procedures that had to be converted to PKP because of DM perforation, trypan blue staining identified remnants of DM and parts of the posterior corneal stroma in 7 eyes. Improved visualization of the residual host tissue enabled complete excision and an overall optimal recipient wound profile.

  6. Core BPEL

    DEFF Research Database (Denmark)

    Hallwyl, Tim; Højsgaard, Espen

    extensions. Combined with the fact that the language definition does not provide a formal semantics, it is an arduous task to work formally with the language (e.g. to give an implementation). In this paper we identify a core subset of the language, called Core BPEL, which has fewer and simpler constructs......, does not allow omissions, and does not contain ignorable elements. We do so by identifying syntactic sugar, including default values, and ignorable elements in WS-BPEL. The analysis results in a translation from the full language to the core subset. Thus, we reduce the effort needed for working...... formally with WS-BPEL, as one, without loss of generality, need only consider the much simpler Core BPEL. This report may also be viewed as an addendum to the WS-BPEL standard specification, which clarifies the WS-BPEL syntax and presents the essential elements of the language in a more concise way...

  7. Ice Cores

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Records of past temperature, precipitation, atmospheric trace gases, and other aspects of climate and environment derived from ice cores drilled on glaciers and ice...

  8. Core benefits

    National Research Council Canada - National Science Library

    Keith, Brian W

    2010-01-01

    This SPEC Kit explores the core employment benefits of retirement, and life, health, and other insurance -benefits that are typically decided by the parent institution and often have significant governmental regulation...

  9. Hollow Core?

    Science.gov (United States)

    Qiao, G. J.; Liu, J. F.; Wang, Yang; Wu, X. J.; Han, J. L.

    We carried out the Gaussian fitting to the profile of PSR B1237+25 and found that six components rather than five are necessary to make a good fit. In the central part, we found that the core emission is not filled pencil beam but is a small hollow cone. This implies that the impact angle could be $\\beta<0.5^\\circ$. The ``hollow core'' is in agreement with Inverse Compton Scattering model of radio pulsars.

  10. Lamellar ichthyosis

    Science.gov (United States)

    ... loss Abnormal finger and toenails Skin of the palms and soles is thickened Treatment Collodion babies usually ... AZ. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. ...

  11. Compressive C-shaped lamellar keratoplasty: a surgical alternative for the management of severe astigmatism from peripheral corneal degeneration.

    Science.gov (United States)

    Cheng, Ching-Li; Theng, Julian T S; Tan, Donald T H

    2005-03-01

    To describe a compressive lamellar surgical technique for treating severe astigmatism in peripheral corneal ectasia. Retrospective, noncomparative, interventional case series. Four eyes of 3 patients with either pellucid or Terrien's marginal corneal degeneration were included in this series. C-shaped lamellar keratoplasty using multiple trephines of different sizes, with deliberate undersizing of the donor graft for a controlled compressive effect, was performed on these patients. Visual acuity outcome and refraction were measured at different intervals at up to 40 months of follow-up. All eyes achieved Snellen visual acuity of 20/40 or better and stable astigmatism ranging from 0 to -2.75 diopter cylinder within 6 months, with no recurrence of corneal thinning or peripheral corneal vascularization. Compressive C-shaped lamellar keratoplasty is able to reduce severe corneal astigmatism in peripheral corneal ectasia and can result in good visual and refractive outcomes with early visual rehabilitation.

  12. The application of Lorentz transmission electron microscopy to the study of lamellar magnetism in hematite-ilmenite

    DEFF Research Database (Denmark)

    Kasama, Takeshi; Dunin-Borkowski, Rafal E.; Asaka, T

    2009-01-01

    Lorentz transmission electron microscopy has been used to study line-scale exsolution microstructures in ilmenite-hematite, as part of a wider investigation of the lamellar magnetism hypothesis. Pronounced asymmetric contrast is visible in out-of-focus Lorentz images of ilmenite lamellae in hemat......Lorentz transmission electron microscopy has been used to study line-scale exsolution microstructures in ilmenite-hematite, as part of a wider investigation of the lamellar magnetism hypothesis. Pronounced asymmetric contrast is visible in out-of-focus Lorentz images of ilmenite lamellae...... in hematite. The likelihood that lamellar magnetism may be responsible for this contrast is assessed using simulations that incorporate interfacial magnetic moments on the (001) basal planes of hematite and ilmenite. The simulations suggest qualitatively that the asymmetric contrast is magnetic in origin...

  13. Refractive outcome of keratoconus treated by combined femtosecond laser and big-bubble deep anterior lamellar keratoplasty.

    Science.gov (United States)

    Buzzonetti, Luca; Laborante, Antonio; Petrocelli, Gianni

    2011-03-01

    To report 1-year follow-up in 11 of 13 eyes with keratoconus treated by deep anterior lamellar keratoplasty with a combined femtosecond laser lamellar resection followed by a big-bubble dissection. Thirteen eyes with keratoconus were treated. Recipient and donor were prepared with the 60-kHz IntraLase femtosecond laser (Abbott Medical Optics). In the recipient, the femtosecond laser, after performing a lamellar cut 100 μm above the thinnest corneal point (measured by Pentacam [Oculus Optikgeräte GmbH]), was used to make a mushroom-shaped resection (anterior diameter, 9 mm; posterior diameter, 8 mm) from the same depth. In the donor, the mushroom lamellar thickness was calculated according to an original model based on the recipient preoperative corneal thickness. Upon removal of the recipient lamella, air was injected into the residual stroma to achieve a big bubble. The keratectomy was continued up to Descemet membrane. The donor was fit into place and sutured using interrupted sutures, which were removed by 8 months postoperative. Corrected distance visual acuity (CDVA) and refractive astigmatism were calculated by manifest refraction, whereas topographic astigmatism and corneal thickness were measured by Pentacam. A big bubble was successfully achieved in 11 eyes. Twelve months after surgery, mean CDVA was 0.52±1.2 (decimal), and refractive sphere and cylinder were -1.50±1.70 diopters (D) and 2.00±2.60 D, respectively. Three (27%) of 11 eyes at 1 year had a manifest refraction spherical equivalent within 1.00 D of emmetropia. Topographic astigmatism was 2.90±1.60 D. The thinnest corneal point was 519±27 μm. This combination of a femtosecond laser lamellar dissection with a big-bubble technique can improve the standardization of deep anterior lamellar keratoplasty for keratoconus. Copyright 2011, SLACK Incorporated.

  14. STAT3 regulates ABCA3 expression and influences lamellar body formation in alveolar type II cells.

    Science.gov (United States)

    Matsuzaki, Yohei; Besnard, Valérie; Clark, Jean C; Xu, Yan; Wert, Susan E; Ikegami, Machiko; Whitsett, Jeffrey A

    2008-05-01

    ATP-Binding Cassette A3 (ABCA3) is a lamellar body associated lipid transport protein required for normal synthesis and storage of pulmonary surfactant in type II cells in the alveoli. In this study, we demonstrate that STAT3, activated by IL-6, regulates ABCA3 expression in vivo and in vitro. ABCA3 mRNA and immunostaining were decreased in adult mouse lungs in which STAT3 was deleted from the respiratory epithelium (Stat3(Delta/Delta) mice). Consistent with the role of STAT3, intratracheal IL-6 induced ABCA3 expression in vivo. Decreased ABCA3 and abnormalities in the formation of lamellar bodies, the intracellular site of surfactant lipid storage, were observed in Stat3(Delta/Delta) mice. Expression of SREBP1a and 1c, SCAP, ABCA3, and AKT mRNAs was inhibited by deletion of Stat3 in type II cells isolated from Stat3(Delta/Delta) mice. The activities of PI3K and AKT were required for normal Abca3 gene expression in vitro. AKT activation induced SREBP expression and increased the activity of the Abca3 promoter in vitro, consistent with the role of STAT3 signaling, at least in part via SREBP, in the regulation of ABCA3. ABCA3 expression is regulated by IL-6 in a pathway that includes STAT3, PI3K, AKT, SCAP, and SREBP. Activation of STAT3 after exposure to IL-6 enhances ABCA3 expression, which, in turn, influences pulmonary surfactant homeostasis.

  15. "Double bubble" deep anterior lamellar keratoplasty for management of corneal stromal pathologies.

    Science.gov (United States)

    Jhanji, Vishal; Beltz, Jacqueline; Sharma, Namrata; Graue, Enrique; Vajpayee, Rasik B

    2011-08-01

    'Big Bubble' deep anterior lamellar keratoplasty (DALK) is becoming an accepted corneal transplantation technique for keratoconus and other anterior stromal corneal pathologies that spare the Descemet's membrane (DM) and endothelium. However, it is not always possible to conclusively recognise formation and identification of the 'Big Bubble'. We describe the surgical technique of DALK called 'Double Bubble' technique that allows the surgeon to definitely and immediately identify the formation of an adequate big bubble. DALK was performed using the 'Double Bubble' technique in twelve eyes of twelve patients with corneal stromal pathologies (keratoconus, 9 eyes; macular corneal dystrophy, 2 eyes; postinfectious keratitis corneal stromal scar, 1 eye) at the Royal Victorian Eye and Ear Hospital, Melbourne. Big bubble was successfully formed in 10 eyes. Maximum-depth deep lamellar keratoplasty was performed in two eyes. There were no instances of intraoperative perforation of the DM. All grafts were clear at last follow-up. Best-corrected visual acuity of ≥20/40 was achieved in all the cases at last follow-up (6-12 months). 'Double Bubble' DALK helps in identification of the big bubble and has the potential to increase the success of standard 'Big Bubble' DALK in patients with corneal stromal pathologies sparing the DM and endothelium.

  16. Neutron spin-echo investigation of the microemulsion dynamics. in bicontinuous lamellar and droplet phases

    Energy Technology Data Exchange (ETDEWEB)

    Mihailescu, M.; Monkenbusch, M.; Endo, H.; Allgaier, J.; Gompper, G.; Stellbrink, J.; Richter, D. [Institut fuer Festkoerperforschung, Forschungszentrum Juelich, 52425 Juelich (Germany); Jakobs, B.; Sottmann, T. [Institut fuer Physikalische Chemie, Universitaet zu Koeln, 50939 Koeln (Germany); Farago, B. [Institut Laue Langevin, 38042 Grenoble (France)

    2002-07-01

    Using neutron spin-echo (NSE) spectroscopy in combination with dynamic light scattering (DLS), we performed an extensive investigation of the bicontinuous phase in ternary water-surfactant-oil microemulsions, with extension to lamellar and droplet phases. The dynamical behavior of surfactant monolayers of decyl-polyglycol-ether (C{sub 10}E{sub 4}) molecules, or mixtures of surfactant with long amphiphilic block-copolymers of type poly-ethylene propylene/poly-ethylene oxide (PEP-PEO) was studied, under comparable conditions. The investigation techniques provide access to different length scales relative to the characteristic periodicity length of the microemulsion structure. Information on the elastic bending modulus is obtained from the local scale dynamics in view of existing theoretical descriptions and is found to be in accordance with small angle neutron scattering (SANS) studies. Evidence for the modified elastic properties and additional interaction of the amphiphilic layers due to the polymer is more pronounced at a larger scale. Experiments on oriented lamellar phases, and also droplet phases, with anchored block-copolymers offer more insight into the effective layer-layer interaction and efficiency boosting associated with the polymers. (orig.)

  17. Femtosecond laser-assisted deep anterior lamellar keratoplasty for keratoconus and keratectasia

    Directory of Open Access Journals (Sweden)

    Yan Lu

    2014-08-01

    Full Text Available AIM: To describe the initial outcomes and safety of femtosecond laser-assisted deep anterior lamellar keratoplasty (DALK for keratoconus and post-LASIKkeratectasia.METHODS:In this non-comparative case series, 10 eyes of 9 patients underwent DALK procedures with a femtosecond laser (Carl Zeiss Meditec AG, Jena, Germany. Of the 9 patients, 7 had keratoconus and 2 had post-LASIK keratectasia. A 500 kHz VisuMax femtosecond laser was used to perform corneal cuts on both donor and recipient corneas.The outcome measures were the uncorrected visual acuity (UCVA, best-corrected visual acuity (BCVA, corneal thickness, astigmatism, endothelial density count (EDC, and corneal power.RESULTS: All eyes were successfully treated. Early postoperative evaluation showed a clear graft in all cases. Intraoperative complications included one case of a small Descemet’s membrane perforation. Postoperatively, there was one case of stromal rejection, one of loosened sutures, and one of wound dehiscence. A normal corneal pattern topography and transparency were restored, UCVA and BCVA improved significantly, and astigmatism improved slightly. There was no statistically significant decrease in EDC.CONCLUSION: Our early results indicate that femtosecond laser-assisted deep anterior lamellar keratoplasty could improve UCVA and BCVA in patients with anterior corneal pathology. This approach shows promise as a safe and effective surgical choice in the treatment of keratoconus and post-LASIK keratectasia.

  18. Effect of onion extract on corneal haze suppression after air assisted lamellar keratectomy

    Science.gov (United States)

    KIM, Soohyun; PARK, Young Woo; LEE, Euiri; PARK, Sang Wan; PARK, Sungwon; NOH, Hyunwoo; KIM, Jong Whi; SEONG, Je Kyung; SEO, Kangmoon

    2015-01-01

    This study evaluated the effect of onion extract on corneal haze suppression after applying the air assisted lamellar keratectomy. The air assisted lamellar keratectomy was performed on 24 canine eyes. They were treated with an artificial tear (group C), prednisolone acetate (group P), onion extract (group O) and TGF-β1 (group T) three times per day from 7 to 28 days after the surgery. Corneal haze occurred on the all eyes and was observed beginning 7 days after the surgery. The haze was significantly decreased in groups P and O from day 14 compared with the group C using the clinical (group P; P=0.021, group O; P=0.037) and objective evaluation method (group P; P=0.021, group O; P=0.039). In contrast, it was significantly increased in group T from day 14 compared with group C based on the clinical (P=0.002) and objective evaluation method (P<0.001). Subsequently, these eyes were enucleated after euthanasia, and immunohistochemistry with α-SMA antibodies was done. The total green intensity for α-SMA was significantly more expressed in group T and significantly less expressed in groups P and O than in group C. Onion extract could have potential as a therapeutic in preventing corneal haze development by suppressing the differentiation of fibroblasts into myofibroblasts. PMID:26607134

  19. Enamel-calibrated lamellar bone reveals long period growth rate variability in humans.

    Science.gov (United States)

    Bromage, Timothy G; Juwayeyi, Yusuf M; Smolyar, Igor; Hu, Bin; Gomez, Santiago; Chisi, John

    2011-01-01

    Mammalian teeth exhibit incremental structures representing successive forming fronts of enamel at varying time scales, including a short daily increment called a cross striation and a long period called a stria of Retzius, the latter of which, in humans, occurs on average every 8-9 days. The number of daily increments between striae is called the repeat interval, which is the same period as that required to form one increment of bone, i.e. the lamella, the fundamental - if not archetypal - unit of bone. Lamellae of known formation time nevertheless vary in width, and thus their measures provide time-calibrated growth rate variability. We measured growth rate variability for as many as 6 years of continuously forming primary incremental lamellar bone from midshaft femur histological sections of sub-Saharan Africans of Bantu origin and known life history. We observed periodic growth rate variability in approximately 6- to 8-week intervals, and in some cases annual rhythms were visible. Endogenous biological periodicities, cycles manifest in the external environment, and/or perturbations of development are all potentially contained within growth rate variability studies of lamellar incremental patterns. Because lamellae are formed within defined periods of time, quantitative measures of widths of individual lamellae provide time-resolved growth rate variability that may reveal rhythms in human bone growth heretofore unknown. Copyright © 2011 S. Karger AG, Basel.

  20. Overstability of lamellar eutectic growth below the minimum-undercooling spacing

    Science.gov (United States)

    Akamatsu, S.; Faivre, G.; Plapp, M.; Karma, A.

    2004-06-01

    We investigate the stability of lamellar eutectic growth by thin-sample directional solidification experiments and two-dimensional phase-field simulations. We find that lamellar patterns can be morphologically stable for spacings smaller than the minimum undercooling spacing λ m . Key to this finding is the direct experimental measurement of the relationship between the front undercooling and spacing, which identifies λ m independently of the Jackson and Hunt (JH) theory and of uncertainties of alloy parameters. This finding conflicts with the common belief that patterns with λ<λ m should be unstable, which is based on the Jackson-Hunt-Cahn assumption that lamellae grow normal to the envelope of the front. Our simulation results reveal that lamellae also move parallel to this envelope to reduce spacing gradients, thereby weakly violating this assumption but strongly overstabilizing patterns for a range of spacing below λ m that increases with G/V (temperature gradient to growth rate ratio). This range is much larger than predicted by previous stability analyses and can be significant for standard experimental conditions. An analytical expression is obtained phenomenologically, which predicts well the variation of the smallest stable spacing with G/V. We also present results that shed light on the history-dependent selection and long-time evolution of the experimentally observed range of spacings.

  1. Preliminary clinical results of posterior lamellar keratoplasty through a sclerocorneal pocket incision.

    Science.gov (United States)

    Melles, G R; Lander, F; van Dooren, B T; Pels, E; Beekhuis, W H

    2000-10-01

    To report the preliminary results of a surgical technique for transplantation of posterior corneal tissue through a sclerocorneal pocket incision for corneal endothelial disorders. Retrospective, noncomparative, interventional cases series. In seven sighted human eyes, a deep stromal pocket was created across the cornea through a 9.0-mm superior scleral incision. A 7.0- or 7.5-mm diameter, posterior lamellar disc was excised and replaced by a 'same size' donor posterior disc, without suture fixation. The scleral incision was sutured. Intra- and postoperative complications, best spectacle-corrected visual acuity, keratometry, topography, biomicroscopy, pachymetry, and endothelial cell density were evaluated. Six to 12 months after surgery, all transplants were clear and in position. Best spectacle-corrected visual acuity was limited by preexisting maculopathies in two eyes and varied from 20/80 to 20/20. Postoperative astigmatism averaged 1. 54 diopters (D; standard deviation [SD] +/- 0.81 D), pachymetry averaged 0.49 mm (SD +/- 0.09 mm), and postoperative endothelial cell density averaged 2520 cells/mm(2) (SD +/- 340 cells/mm(2)). In one eye, a microperforation occurred during stromal pocket dissection so that the procedure was converted into a penetrating keratoplasty. Posterior lamellar keratoplasty through a sclerocorneal pocket incision is a feasible surgical approach to manage corneal endothelial disorders.

  2. Local thermomechanical analysis of a microphase-separated thin lamellar PS-b-PEO film.

    Science.gov (United States)

    Rice, Reginald H; Mokarian-Tabari, Parvaneh; King, William P; Szoszkiewicz, Robert

    2012-09-18

    We use atomic force microscopy (AFM) and hot tip AFM (HT-AFM) to thermophysically characterize a 30 nm thick film of poly(styrene-block-ethylene oxide), PS-b-PEO, and to modify its lamellar patterns having spacing of 39 ± 3 nm. AFM tip scans of the polymer film induce either abrasive surface patterns or nanoscale ripples, which depend upon the tip force, temperature, and number of scans. The evolution of the lamellar patterns is explained by the polymer film molecular structure and mode I crack propagation in the polymer combined with the stick-and-slip behavior of the AFM tip. The HT-AFM measurements at various tip-sample temperatures and scanning speeds yield several thermophysical quantities: the PEO melting temperature of 54 ± 12 °C, the PS glass transition temperature of 54 ± 12 °C, the PS-b-PEO specific heat of 3.6 ± 2.7 J g(-1) K(-1), the PEO melting enthalpy of 111 ± 88 J g(-1), and the free energy of Helmholtz for PEO unfolding (and melting) of 10(-20) J nm(-2). These quantities are obtained for PS-b-PEO volumes of 30,000 nm(3), which correspond to 30 ag of the polymer.

  3. Transverse depth-dependent changes in corneal collagen lamellar orientation and distribution

    Science.gov (United States)

    Abass, Ahmed; Hayes, Sally; White, Nick; Sorensen, Thomas; Meek, Keith M.

    2015-01-01

    It is thought that corneal surface topography may be stabilized by the angular orientation of out-of plane lamellae that insert into the anterior limiting membrane. In this study, micro-focus X-ray scattering data were used to obtain quantitative information about lamellar inclination (with respect to the corneal surface) and the X-ray scatter intensity throughout the depth of the cornea from the centre to the temporal limbus. The average collagen inclination remained predominantly parallel to the tissue surface at all depths. However, in the central cornea, the spread of inclination angles was greatest in the anterior-most stroma (reflecting the increased lamellar interweaving in this region), and decreased with tissue depth; in the peripheral cornea inclination angles showed less variation throughout the tissue thickness. Inclination angles in the deeper stroma were generally higher in the peripheral cornea, suggesting the presence of more interweaving in the posterior stroma away from the central cornea. An increase in collagen X-ray scatter was identified in a region extending from the sclera anteriorly until about 2 mm from the corneal centre. This could arise from the presence of larger diameter fibrils, probably of scleral origin, which are known to exist in this region. Incorporation of this quantitative information into finite-element models will further improve the accuracy with which they can predict the biomechanical response of the cornea to pathology and refractive procedures. PMID:25631562

  4. [Update: Deep anterior lamellar keratoplasty (DALK) for keratoconus. When, how and why].

    Science.gov (United States)

    Cursiefen, C; Schaub, F; Bachmann, B

    2016-03-01

    The treatment of keratoconus has been significantly expanded in recent years. In addition to the previous options for correction by fitting hard contact lenses and penetrating keratoplasty (PK), corneal cross-linking and lamellar transplantation techniques have been added. The aim of this review article is to highlight currently available options for minimization of complications and standardization of deep anterior lamellar keratoplasty (DALK) for keratoconus. This article summarizes our own data and gives a review of the literature in PubMed. Performing DALK can provide keratoconus patients with corneal grafts with considerably longer graft survival and a reduced risk of complications. The DALK procedure provides numerous advantages over PK, especially the reduced intraoperative opening of the eye, which thus reduces the risk of serious intraoperative complications. A further benefit is the complete absence of postoperative endothelial immune reactions as the recipient's endothelium remains untouched. The absence of endothelial immune reactions is especially advantageous for young patients with keratoconus and patients with an increased risk of graft rejection, e.g. in atopic dermatitis; however, there are also typical complications of DALK that do not occur during PK. The outlined strategies for standardization of DALK and avoidance of intraoperative and postoperative complications should make DALK safer and more reproducible and lead to possible establishment as a standard procedure in keratokonus.

  5. Transverse depth-dependent changes in corneal collagen lamellar orientation and distribution.

    Science.gov (United States)

    Abass, Ahmed; Hayes, Sally; White, Nick; Sorensen, Thomas; Meek, Keith M

    2015-03-06

    It is thought that corneal surface topography may be stabilized by the angular orientation of out-of plane lamellae that insert into the anterior limiting membrane. In this study, micro-focus X-ray scattering data were used to obtain quantitative information about lamellar inclination (with respect to the corneal surface) and the X-ray scatter intensity throughout the depth of the cornea from the centre to the temporal limbus. The average collagen inclination remained predominantly parallel to the tissue surface at all depths. However, in the central cornea, the spread of inclination angles was greatest in the anterior-most stroma (reflecting the increased lamellar interweaving in this region), and decreased with tissue depth; in the peripheral cornea inclination angles showed less variation throughout the tissue thickness. Inclination angles in the deeper stroma were generally higher in the peripheral cornea, suggesting the presence of more interweaving in the posterior stroma away from the central cornea. An increase in collagen X-ray scatter was identified in a region extending from the sclera anteriorly until about 2 mm from the corneal centre. This could arise from the presence of larger diameter fibrils, probably of scleral origin, which are known to exist in this region. Incorporation of this quantitative information into finite-element models will further improve the accuracy with which they can predict the biomechanical response of the cornea to pathology and refractive procedures.

  6. Femtosecond laser and big-bubble deep anterior lamellar keratoplasty: a new chance.

    Science.gov (United States)

    Buzzonetti, Luca; Petrocelli, Gianni; Valente, Paola

    2012-01-01

    Purpose. To report the 12-month follow-up after big-bubble deep anterior lamellar keratoplasty (DALK) assisted by femtosecond laser that we have called IntraBubble. Methods. A 60 kHz IntraLase femtosecond laser (Abbott Medical Optics) firstly created a 30° angled intrastromal channel to insert the air injection cannula, 50 μ above the thinnest corneal site measured by Sirius Scheimpflug camera (CSO, Firenze, Italy), then performed a full lamellar cut 100 μ above the thinnest corneal point, and from the same corneal depth, created a mushroom incision. The lamella was removed, and the smooth cannula of Fogla was inserted into the stromal channel and air was injected to achieve a big bubble. The follow up is 12 months, and sutures were removed by the 10th postoperative month in all patients. Best Corrected Visual Acuity (BCVA), spherical equivalent and, by Sirius Scheimpflug camera (CSO, Firenze, Italy) keratometric astigmatism were evaluated. Results. All procedures were completed as DALK except 2 converted to PK because an inadvertent intraoperative macroperforation occurred. Mean postoperative BCVA was 0.8, mean spherical equivalent was -3.5 ± 1.7 D, and mean keratometric astigmatism was 4.8 ± 3.1 D. Conclusion. The femtosecond laser could standardize the big-bubble technique in DALK, reducing the risk of intraoperative complications and allowing good refractive outcomes.

  7. Femtosecond Laser and Big-Bubble Deep Anterior Lamellar Keratoplasty: A New Chance

    Science.gov (United States)

    Buzzonetti, Luca; Petrocelli, Gianni; Valente, Paola

    2012-01-01

    Purpose. To report the 12-month follow-up after big-bubble deep anterior lamellar keratoplasty (DALK) assisted by femtosecond laser that we have called IntraBubble. Methods. A 60 kHz IntraLase femtosecond laser (Abbott Medical Optics) firstly created a 30° angled intrastromal channel to insert the air injection cannula, 50 μ above the thinnest corneal site measured by Sirius Scheimpflug camera (CSO, Firenze, Italy), then performed a full lamellar cut 100 μ above the thinnest corneal point, and from the same corneal depth, created a mushroom incision. The lamella was removed, and the smooth cannula of Fogla was inserted into the stromal channel and air was injected to achieve a big bubble. The follow up is 12 months, and sutures were removed by the 10th postoperative month in all patients. Best Corrected Visual Acuity (BCVA), spherical equivalent and, by Sirius Scheimpflug camera (CSO, Firenze, Italy) keratometric astigmatism were evaluated. Results. All procedures were completed as DALK except 2 converted to PK because an inadvertent intraoperative macroperforation occurred. Mean postoperative BCVA was 0.8, mean spherical equivalent was -3.5 ± 1.7 D, and mean keratometric astigmatism was 4.8 ± 3.1 D. Conclusion. The femtosecond laser could standardize the big-bubble technique in DALK, reducing the risk of intraoperative complications and allowing good refractive outcomes. PMID:22496960

  8. Lecithin/sphingomyelin ratio and lamellar body count for fetal lung maturity: a meta-analysis.

    Science.gov (United States)

    Besnard, Anouk E; Wirjosoekarto, Soetinah A M; Broeze, Kimiko A; Opmeer, Brent C; Mol, Ben Willem J

    2013-07-01

    To determine and compare the diagnostic accuracy of the lecithin/sphingomyelin (L/S) ratio and lamellar body count (LBC) in the prediction of neonatal respiratory distress syndrome (RDS). A systematic review was performed to identify studies comparing either the L/S ratio or the LBC with the occurrence of RDS published between January 1999 and February 2009. Two independent reviewers performed study selection and data extraction. For each study sensitivity and specificity were calculated. Summary receiver-operating characteristics (ROC) curves, assessing the diagnostic performance of both tests, were constructed. A subgroup analysis was performed to estimate the sensitivity and specificity of the various cut-off values. 13 studies were included. The ROC curves of the collected data illustrate that the LBC and L/S ratio perform equally well in the prediction of RDS. Comparison of the two summary ROC curves of each test indicates that the diagnostic performance of LBC might even have a slight advantage over L/S ratio. Due to the wide cut-off range it was not possible to define specific cut-off values with the best accuracy. We recommend replacing the L/S ratio as gold standard with the lamellar body count since the LBC is easy to perform, rapid, inexpensive, and available to all hospitals 24h per day. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  9. Lamellar Microdomains of Block-Copolymer-Based Ionic Supramolecules Exhibiting a Hierarchical Self-Assembly

    DEFF Research Database (Denmark)

    Ayoubi, Mehran Asad; Almdal, Kristoffer; Zhu, Kaizheng

    2014-01-01

    (Cn; n = 8, 12, and 16) trimethylammonium counterions (i.e., side chains) at various ion (pair) fractions X [i.e., counterion/side-chain grafting density; X = number of alkyl counterions (i.e., side chains) per acidic group of the parent PMAA block] these L-b-AC ionic supramolecules exhibit...... a spherical-in-lamellar hierarchical self-assembly. For these systems, (1) the effective Flory-Huggins interaction parameter between L- and AC-blocks chi'(Cn/x) was extracted, and (2) analysis of the lamellar microdomains showed that when there is an increase in X, alkyl counterion (i.e., side chain) length l......Based on a parent diblock copolymer of poly(styrene)-b-poly(methacrylic acid), PS-b-PMAA, linear-b-amphiphilic comb (L-b-AC) ionic supramolecules [Soft Matter 2013, 9, 1540-1555] are synthesized in which the poly(methacrylate) backbone of the ionic supramolecular AC-block is neutralized by alkyl...

  10. Fishnet statistics for probabilistic strength and scaling of nacreous imbricated lamellar materials

    Science.gov (United States)

    Luo, Wen; Bažant, Zdeněk P.

    2017-12-01

    Similar to nacre or brick-and-mortar structures, imbricated lamellar structures are widely found in natural and man-made materials and are of interest for biomimetics. These structures are known to be rather insensitive to defects and to have a very high fracture toughness. Their deterministic behavior has been intensely studied, but statistical studies have been rare and is so far there is no undisputed theoretical basis for the probability distribution of strength of nacre. This paper presents a numerical and theoretical study of the PDF of strength and of the corresponding statistical size effect. After a reasonable simplifications of the shear bonds, an axially loaded lamellar shell is statistically modelled as a square fishnet pulled diagonally. A finite element (FE) model is developed and used in Monte Carlo simulations of strength. An analytical model for failure probability of the fishnet is developed and matched to the computed statistical histograms of strength for various sizes. It appears that, with increasing size, the pdf of strength slowly transits from Gaussian to Weilbull distribution but the transition is different from that previously obtained at Northwestern for quasibrittle materials of random heterogeneous mesostructure.

  11. Intense luminescence emission from rare-earth-doped MoO3 nanoplates and lamellar crystals for optoelectronic applications

    Science.gov (United States)

    Vila, M.; Díaz-Guerra, C.; Jerez, D.; Lorenz, K.; Piqueras, J.; Alves, E.

    2014-09-01

    Strong and stable room-temperature photoluminescence (PL) emission is achieved in MoO3 nanoplates and lamellar crystals doped with Er and Eu by ion implantation and subsequent annealing. Micro-Raman and PL spectroscopy reveal that optical activation of the rare earth ions and recovery of the original MoO3 structure are achieved for shorter annealing treatments and for lower temperatures in nanoplates, as compared with lamellar crystals. Er seems to be more readily incorporated into optically active sites in the oxide lattice than Eu. The influence of the dimensionality of the host sample on the characteristics of the PL emission of both rare earth dopants is addressed.

  12. Outstanding compressive creep strength in Cr/Ir-codoped (Mo0.85Nb0.15)Si2crystals with the unique cross-lamellar microstructure.

    Science.gov (United States)

    Hagihara, Koji; Ikenishi, Takaaki; Araki, Haruka; Nakano, Takayoshi

    2017-06-21

    A (Mo 0.85 Nb 0.15 )Si 2 crystal with an oriented, lamellar, C40/C11 b two-phase microstructure is a promising ultrahigh-temperature (UHT) structural material, but its low room-temperature fracture toughness and low high-temperature strength prevent its practical application. As a possibility to overcome these problems, we first found a development of unique "cross-lamellar microstructure", by the cooping of Cr and Ir. The cross-lamellar microstructure consists of a rod-like C11 b -phase grains that extend along a direction perpendicular to the lamellar interface in addition to the C40/C11 b fine lamellae. In this study, the effectiveness of the cross-lamellar microstructure for improving the high-temperature creep deformation property, being the most essential for UHT materials, was examined by using the oriented crystals. The creep rate significantly reduced along a loading orientation parallel to the lamellar interface. Furthermore, the degradation in creep strength for other loading orientation that is not parallel to the lamellar interface, which has been a serious problem up to now, was also suppressed. The results demonstrated that the simultaneous improvement of high-temperature creep strength and room temperature fracture toughness can be first accomplished by the development of unique cross-lamellar microstructure, which opens a potential avenue for the development of novel UHT materials as alternatives to existing Ni-based superalloys.

  13. Queratitis lamelar difusa después del Lasik Diffuse lamellar keratitis after LASIK

    Directory of Open Access Journals (Sweden)

    Lorelei Ortega Díaz

    2010-12-01

    Full Text Available OBJETIVO: Describir el comportamiento de la queratitis lamelar difusa como complicación después de emplear la técnica quirúrgica queratomileusis in situ con láser. MÉTODOS: Se realizó un estudio descriptivo, de corte transversal en el Servicio de Cirugía Refractiva Corneal del Instituto Cubano de Oftalmología "Ramón Pando Ferrer" en el último trimestre del año 2008. La muestra quedó conformada por 16 ojos a los que se les realizó la queratomileusis in situ con láser como técnica quirúrgica para corregir ametropía y que presentaron complicaciones con esta cirugía. Se analizaron variables como la agudeza visual sin corrección; los ojos con esta complicación fueron analizados según la clasificación de Linebarger. RESULTADOS: La frecuencia de queratitis lamelar difusa fue de 3,0 por cada 100. La agudeza visual no corregida se comportó entre 0,8 y 1,0 en 12 ojos de 16 afectados, el estadio 1 se presentó en 12 ojos. CONCLUSIONES: La queratitis lamelar difusa es una complicación poco frecuente, los casos que la padecieron alcanzaron una buena agudeza visual final sin corrección. Predominó la forma leve de este cuadro.OBJECTIVE: To describe the situation of Diffuse lamellar keratitis as a complication after in situ keratomileusis with laser. METHODS: A descriptive cross-sectional study was carried out in the Refractive Corneal Service of "Ramón Pando Ferrer" Cuban Institute of Ophthalmology during the last quarter of 2008. The sample embraced 16 eyes that underwent in situ keratomileusis plus laser as the refractive procedure to correct ametropy and presented with some complications. Visual acuity without correction was one the analyzed variables and the eyes with this type of complication were classified according to Linebarger´s classification. RESULTS: The diffuse lamellar keratitis frequency was 3.0 per one hundred cases, the visual acuity without correction was 0.8 to 1.0 in 12 out of 16 eyes whereas stage 1 was

  14. Long-term results of femtosecond laser-assisted sutureless anterior lamellar keratoplasty.

    Science.gov (United States)

    Shousha, Mohamed Abou; Yoo, Sonia H; Kymionis, George D; Ide, Takeshi; Feuer, William; Karp, Carol L; O'Brien, Terrence P; Culbertson, William W; Alfonso, Eduardo

    2011-02-01

    To evaluate the long-term results of femtosecond laser-assisted anterior lamellar keratoplasty (FALK) for anterior corneal pathologies. Retrospective, noncomparative, interventional case series. Thirteen consecutive patients who underwent FALK for anterior corneal pathologies. Femtosecond laser-assisted sutureless anterior lamellar keratoplasty. Best spectacle-corrected visual acuity (BSCVA), manifest refraction, need for adjunctive surgery, and complications. Follow-up ranged from 12 to 69 months (mean = 31 months). The BSCVA was significantly improved over preoperative values at the 12-, 18-, 24-, and 36-month visits. A BSCVA greater than 20/30 was achieved in 54% of patients at the 12-month visit when all 13 patients were available for follow-up, in 50% and 33% of patients at the 18- and 24-month visits, respectively, when 12 patients were available, and in 60% and 50% of patients at the 36- and 48-month visits when 5 and 2 patients were available, respectively. The BSCVA of the eye that completed the 60- and 70-month visits was 20/50. Patients achieved a mean gain of 5 lines of BSCVA at the 6-, 12-, 18-, and 24-month visits, 4 lines at the 36-month visit, 5 lines at the 48-month visit, and 6 lines at the 60- and 72-month visits. Two patients lost a mean of 1.5 lines of BSCVA because surface haze developed after photorefractive keratectomy (PRK) and granular dystrophy recurred in the graft. At a mean of 5 weeks postoperatively, 83.3% of patients achieved BSCVA within 2 lines of that recorded at the 24-month visit. At the 12-month visit, mean spherical equivalent and refractive astigmatism were -0.4 diopters (D) and 2.2 D, respectively, with no significant shift from preoperative values or values recorded in different follow-up visits. Adjunctive surgeries included phototherapeutic keratectomy, PRK, cataract extraction, and epithelial ingrowth debridement. Complications included residual corneal pathology, mild interface haze, anisometropia, recurrence of

  15. Deep lamellar endothelial keratoplasty visual acuity, astigmatism, and endothelial survival in a large prospective series.

    Science.gov (United States)

    Terry, Mark A; Ousley, Paula J

    2005-09-01

    To report the 6-month results for the treatment of endothelial dysfunction in a large, prospective series of deep lamellar endothelial keratoplasty (DLEK) procedures. Prospective, noncomparative, interventional case series. One hundred eyes of 88 patients with corneal edema from Fuchs' dystrophy and pseudophakia. A limbal, scleral, partial-depth incision provided access for a deep lamellar corneal pocket dissection. Two eyes were converted to penetrating keratoplasty (PK) at the time of DLEK surgery because of poor dissections. Of the 98 eyes that had completed DLEK surgeries, 36 eyes received a large-incision technique (9-mm scleral access incision) and 62 eyes received a small-incision technique (5-mm scleral access incision). A 7.5- to 8.0-mm posterior lamellar disc of recipient tissue then was excised and replaced through the pocket with a similar size donor disc containing healthy endothelium. A temporary air bubble in the anterior chamber was used for donor tissue adherence, and no surface corneal incisions or sutures were necessary. Preoperative and postoperative best spectacle-corrected visual acuity (BSCVA), manifest refraction (MR) astigmatism, and endothelial cell density (ECD) were evaluated prospectively. At 6 months after surgery, all 98 DLEK corneas were clear and the grafts were healed in good position. The mean BSCVA was 20/46, with a range between 20/20 and 20/400. The average MR astigmatism was 1.34+/-0.86 diopters (D), representing an average change in astigmatism from before surgery of +0.28+/-1.08 D (P = 0.013). The average ECD at 6 months was 2140+/-427 cells/mm2, representing a mean cell loss from preoperative donor cell measurements of 25%. The DLEK procedure, with its absence of corneal surface incisions and sutures, preserves the normal corneal topography, minimizes astigmatism, and provides a healthy donor endothelial cell count and function. The DLEK procedure represents a reasonable alternative to PK, and compared with historical PK

  16. Ca2+ entry is essential for cell strain-induced lamellar body fusion in isolated rat type II pneumocytes

    NARCIS (Netherlands)

    Frick, Manfred; Bertocchi, Cristina; Jennings, Paul; Haller, Thomas; Mair, Norbert; Singer, Wolfgang; Pfaller, Walter; Ritsch-Marte, Monika; Dietl, Paul

    Using a new equibiaxial strain device, we investigated strain-induced Ca2+ signals and their relation to lamellar body (LB) exocytosis in single rat alveolar type II (AT II) cells. The strain device allows observation of single cells while inducing strain to the entire substratum. AT II cells

  17. Predicting lung maturity in preterm rupture of membranes via lamellar bodies count from a vaginal pool: a cohort study

    Directory of Open Access Journals (Sweden)

    Nachum Zohar

    2009-10-01

    Full Text Available Abstract Background Amniocentesis is the accepted mode of attaining amniotic fluid to perform tests for fetal lung maturity. The purpose of this study was to validate a non-invasive fetal lung maturity test by counting lamellar bodies from a vaginal pool among women with preterm premature rupture of membranes. Methods In a prospective study, amniotic fluid specimens were collected from a vaginal pool from women after preterm premature rupture of membranes with gestational age between 27 and 36 completed weeks. Receiver operating characteristics curve was estimated to assess the threshold of lamellar bodies' count that may predict fetal lung maturity. Results Seventy-five specimens were collected of which 17 were between 32 to 34 weeks. A lamellar bodies' count of 28,000 or more predicted mature fetus 100% of the time (specificity among all women and also among women between 32 to 34 weeks. The sensitivity was 72% among all and 92% when gestational age was between 32 to 34 weeks. A count of 8,000 or less, predicted respiratory distress syndrome with a sensitivity of 98% among the whole group. Conclusion Counting of lamellar bodies in amniotic fluid from a vaginal pool may be used to predict fetal lung maturity.

  18. Research of lamellar lubricants mechanical-and-physical properties and structure

    Science.gov (United States)

    Morgunov, A. P.; Masyagin, V. B.; Derkach, V. V.; Matveev, N. A.

    2017-06-01

    in the article ascertaining the applicability of lamellar solid lubricants is considered for the purpose of wear resistance increase of metal surface elements by their contact interaction in different operational conditions. Forms of binding in the structure of solid lubricants are described through the example of molybdenum disulfide MoS2, as well as change properties at standard and high (350-480°C) exposure temperature. After solid lubricant application the additional treatment is made on the work surface of flanged wheels in the wheel set of a locomotive using plastic deformation for getting of multilevel micro relief resulting in working service increase of the wheel set in comparison with control set from 1.6 to 3 times.

  19. Visual outcome of penetrating keratoplasty, deep anterior lamellar keratoplasty and Descemet membrane endothelial keratoplasty.

    Science.gov (United States)

    Garrido, Clàudia; Cardona, Genís; Güell, Josep L; Pujol, Jaume

    2017-11-13

    A single-center, cross-sectional study was designed to assess and compare objective and subjective quality of vision of patients intervened with penetrating keratoplasty (PK), deep anterior lamellar keratoplasty (DALK) and Descemet membrane endothelial keratoplasty (DMEK). Forty-six patients previously intervened with PK (22 eyes), DALK (7 eyes) and DMEK (17 eyes) were recruited. Visual evaluation included spherical and cylindrical refraction, distance corrected visual acuity (DCVA), photopic contrast sensitivity (CS), optical quality, measured with the HD Analyzer (objective scattering index [OSI], MTF cut-off and Strehl ratio), and ocular and corneal aberrometry, measured with the KR-1W Wavefront Analyzer. Statistically significant between-group differences were found in age (p=0.006, DMEK patients were older) and time since surgery (pvisual function parameters under evaluation. Copyright © 2017 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.

  20. Successful deep anterior lamellar keratoplasty following multiple failed limbal transplantations for chronic ocular burns.

    Science.gov (United States)

    Toor, Gurpal Singh; Basu, Sayan; MacNeil, Sheila; Sangwan, Virender S

    2012-09-21

    A 9-year-old girl with severe unilateral ocular surface disease due to limbal stem cell deficiency following chemical injury underwent autologous cultivated limbal epithelial transplantation (CLET) twice in her right eye that failed to improve the condition of the ocular surface. On both occasions, limbal biopsies were obtained from the unaffected left eye. Since further attempts at CLET were not considered to be safe, deep anterior lamellar keratoplasty (DALK) was performed instead. DALK was complicated by postoperative Descemet's membrane detachment, which was successfully treated. Two years post-DALK the patient had a clear graft, stable ocular surface and visual acuity of 20/80. The mechanism by which CLET allows a patient to repopulate the ocular surface is as yet unknown. This case highlights that although clinically little had changed following two failed CLET surgeries, some subclinical improvement must have taken place for a DALK to remain successful after 2 years.

  1. Neutron spin-echo investigation of the microemulsion dynamics. in bicontinuous lamellar and droplet phases

    CERN Document Server

    Mihailescu, M; Endo, H; Allgaier, J; Gompper, G; Stellbrink, J; Richter, D; Jakobs, B; Sottmann, T; Faragó, B

    2002-01-01

    Using neutron spin-echo (NSE) spectroscopy in combination with dynamic light scattering (DLS), we performed an extensive investigation of the bicontinuous phase in ternary water-surfactant-oil microemulsions, with extension to lamellar and droplet phases. The dynamical behavior of surfactant monolayers of decyl-polyglycol-ether (C sub 1 sub 0 E sub 4) molecules, or mixtures of surfactant with long amphiphilic block-copolymers of type poly-ethylene propylene/poly-ethylene oxide (PEP-PEO) was studied, under comparable conditions. The investigation techniques provide access to different length scales relative to the characteristic periodicity length of the microemulsion structure. Information on the elastic bending modulus is obtained from the local scale dynamics in view of existing theoretical descriptions and is found to be in accordance with small angle neutron scattering (SANS) studies. Evidence for the modified elastic properties and additional interaction of the amphiphilic layers due to the polymer is mo...

  2. Behavior of Plastic Deformation and Crack Propagation on Fully Lamellar GAMMA-TiAl Alloy

    Science.gov (United States)

    Song, Ming; Mao, Guangjie; Ma, Yue; Gong, Shengkai

    Practical residual strain field around the microcrack tip of fully lamellar γ-TiAl alloy was estimate the by digital image correlation (DIC) technology with in-situ SEM observation. And the macro plastic deformation before fracture of such low ductility alloys was observed. The results showed that the size of plastic zone around microcrack tip was 2 ~ 10µm which was much more smaller than the calculated value by fracture mechanics. During the magnified observation on the plastic deformation region, a series of microcracks were observed in the specimen without macro cracking. Furthermore, the size of distribution region of the microcracks were in the same order of magnitude with the calculated plastic zone near primary crack tip which just reflected the comprehensive effect of microcracks and the plastic deformation on the tips of them.

  3. Early byzantine lamellar armour from Carthago Spartaria (Cartagena, Spain

    Directory of Open Access Journals (Sweden)

    Vizcaíno Sánchez, Jaime

    2008-12-01

    Full Text Available This article presents an Early Byzantine lamellar armour, retrieved in the excavations at the quarter built over the Roman Theatre of Cartagena. The armour has close parallels with contemporary known material from the central and eastern Mediterranean or other sites, and it is an important find which increases the body of archeological evidence about Byzantine presence in Spania.

    Este artículo presenta una coraza laminar protobizantina hallada en las excavaciones del barrio construido sobre el teatro romano de Cartagena. La coraza tiene estrechos paralelos con materiales contemporáneos del Mediterráneo Central y Oriental u otros lugares, y es un importante hallazgo que incrementa la nómina de evidencias arqueológicas acerca de la presencia bizantina en Spania.

  4. [Neovascular invasion of the endothelio-descemetic interface occurring after deep anterior lamellar keratoplasty].

    Science.gov (United States)

    Pinsard, L; Malet, F; Colin, J; Touboul, D

    2013-05-01

    The endothelio-descemetic interface (EDI) of a deep anterior lamellar keratoplasty (DALK) may become the locus of a neovascular proliferation. Bevacizumab (Avastin) is an antiangiogenic alternative available for curative treatment in deep corneal neovascularization. We report the case of a 49-year-old woman who had received two arcuate relaxing incisions for high astigmatism after DALK. She developed graft rejection associated with significant neovascular stromal invasion in the EDI of the graft-host interface. Two subconjunctival injections of bevacizumab 1 month apart as well as thermocauterization of the feeding vessel were necessary and effective. No recurrence has been observed after 2 years of follow-up. Corneal neovascularization can be a cause of DALK rejection. A combination of anti-antiangiogenic and physical methods may abort graft rejection and permanently restore graft function. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  5. Intrastromal Corneal Ring Segments for Astigmatism Correction after Deep Anterior Lamellar Keratoplasty

    Science.gov (United States)

    Coscarelli, Sandro; Ferrara, Paulo; Araújo, Luana P. N.; Ávila, Marcos; Torquetti, Leonardo

    2017-01-01

    Background. To evaluate the change in corneal astigmatism after intrastromal corneal ring segment (ICRS) implantation in keratoconus patients with previous deep anterior lamellar keratoplasty (DALK). Design was a longitudinal, retrospective, interventional study. The study included 25 eyes of 24 patients with keratoconus who had DALK performed at least two years prior to ICRS implantation. All patients had a clear corneal graft with up to 8.00 D of corneal astigmatism and intolerance to contact lenses. The studied parameters were age, sex, corrected distance visual acuity (CDVA), maximum keratometry (K1), minimum keratometry (K2), spherical equivalent, and astigmatism. There was a statistically significant decrease in the postintervention analysis as follows: 3.5 D reduction in K1 (p astigmatism reduced from 3.87 D preoperatively to 1.90 D postoperatively (p astigmatism after DALK as it yields significant visual, topographic, and refractive results. PMID:28951784

  6. Rheology of the lamellar liquid-crystalline phase in polyethoxylated alcohol/water/heptane systems.

    Directory of Open Access Journals (Sweden)

    Gallegos, C.

    2005-06-01

    Full Text Available Linear viscoelastic tests as well as transient and steady flow experiments were carried out on lamellar liquid crystalline samples of poly (oxyethylene alcohol/water/heptane systems. The effect of surfactant and heptane concentrations on the rheological properties of the lamellar mesophase was investigated. The mechanical spectrum inside the linear viscoelastic regime shows, in all cases, a well-developed plateau region in the whole frequency range studied. The values of the dynamic functions were higher for intermediate surfactant or heptane concentrations indicative of a major development of the elastic network in the midrange of existence of the lamellar phase. Transient and steady flow experiments point out a shear-induced evolution of the lamellar microstructure. Different power law regions with different values of the flow index were detected in the viscosity versus shear rate plots. These shear-induced structural modifications were confirmed by using polarizing microscopy in an optical shearing cell. Structural modifications appear to be highly influenced by shear rate. In general, applying relatively high constant shear rates, the alignment of the bilayers followed by the appearance of the “oily streaks” structure was observed. Appearance of shear-induced vesicles occurs at high heptane content, as indicates the texture of close-packed monodisperse spherulites detected by polarizing microscopy.n este trabajo se han estudiado las propiedades reológicas de una fase líquido-cristalina laminar contenida en un sistema alcohol polietoxilado/agua/heptano, mediante ensayos viscoelásticos lineales, estacionarios y transitorios. El efecto de distintas variables como la composición de tensioactivo y heptano sobre dichas propiedades reológicas ha sido analizado. El espectro mecánico obtenido de la fase laminar muestra en todos los casos una región “plateau” en el intervalo de frecuencias estudiado así como mayores valores

  7. Ru complexes of Hoveyda-Grubbs type immobilized on lamellar zeolites: activity in olefin metathesis reactions.

    Science.gov (United States)

    Balcar, Hynek; Žilková, Naděžda; Kubů, Martin; Mazur, Michal; Bastl, Zdeněk; Čejka, Jiří

    2015-01-01

    Hoveyda-Grubbs type catalysts with cationic tags on NHC ligands were linker-free immobilized on the surface of lamellar zeolitic supports (MCM-22, MCM-56, MCM-36) and on mesoporous molecular sieves SBA-15. The activity of prepared hybrid catalysts was tested in olefin metathesis reactions: the activity in ring-closing metathesis of citronellene and N,N-diallyltrifluoroacetamide decreased in the order of support MCM-22 ≈ MCM-56 > SBA-15 > MCM-36; the hybrid catalyst based on SBA-15 was found the most active in self-metathesis of methyl oleate. All catalysts were reusable and exhibited low Ru leaching (<1% of Ru content). XPS analysis revealed that during immobilization ion exchange between Hoveyda-Grubbs type catalyst and zeolitic support occurred in the case of Cl(-) counter anion; in contrast, PF6 (-) counter anion underwent partial decomposition.

  8. The effect of octyl glucoside on rheological behavior of diluted and concentrated lamellar phases.

    Science.gov (United States)

    Granizo, N; Alvarez, M; Valiente, M

    2006-06-01

    We have investigated the rheological properties of lamellar liquid crystal formed by nonionic surfactants at low and high surfactant concentrations with a small amount of octyl glucoside and their relationship with the topology of the bilayer. Rheology is a specific signature of each bilayer topology. The decrease in viscosity by increasing the shear rate according to a power law with exponent close to -0.8 was found for the concentrated system of LSB/1-butanol/water and 1% in weight of OG. On the contrary, the decrease in the viscosity by increasing the shear rate for the diluted system is less pronounced with lower exponent values. The rheological data agrees with the presence of vesicles. A special case is the system with benzyl alcohol. The apparent viscosity does not follow the same power law than for alkanols.

  9. Management of canine corneal squamous cell carcinoma with lamellar keratectomy and strontium 90 plesiotherapy: 3 cases.

    Science.gov (United States)

    Nevile, Jessica C; Hurn, Simon D; Turner, Andrew G; McCowan, Christina

    2015-05-01

    To report three cases of canine corneal squamous cell carcinoma (SCC) treated with strontium 90 beta radiation as an adjunct to surgical excision. Corneal SCC was excised with lamellar keratectomy. This was followed by local application of strontium 90 beta radiation. Available case follow-up times range from 3 to 50 months. One case suffered a recurrence 5 months following initial excision and strontium 90 treatment. Strontium 90 beta radiation has been used extensively as an adjunctive treatment for equine corneal SCC and in other canine ocular tumors; however, there is a paucity of information regarding use in canine corneal SCC. The cases presented here suggest its use following keratectomy may be helpful in preventing disease recurrence. At the dosage used, severe adverse effects were not observed. © 2014 American College of Veterinary Ophthalmologists.

  10. Experimental evidence for lamellar magnetism in hemo-ilmenite by polarized neutron scattering

    DEFF Research Database (Denmark)

    Brok, Erik; Sales, Morten; Lefmann, Kim

    2014-01-01

    Large local anomalies in the Earth's magnetic field have been observed in Norway, Sweden, and Canada. These anomalies have been attributed to the unusual magnetic properties of naturally occurring hemo-ilmenite, consisting of a paramagnetic ilmenite host (alpha-Fe2O3-bearing FeTiO3) with exsolution...... lamellae (approximate to 3 μm m thick) of canted antiferromagnetic hematite (FeTiO3-bearing α-Fe2O3) and the mutual exsolutions of the same phases on the micron to nanometer scale. The origin of stable natural remanent magnetization (NRM) in this system has been proposed to be uncompensated magnetic...... moments in the contact layers between the exsolution lamellae. This lamellar magnetism hypothesis is tested here by using polarized neutron diffraction to measure the orientation of hematite spins as a function of an applied magnetic field in a natural single crystal of hemo-ilmenite from South Rogaland...

  11. Minimal compliance design for metal–ceramic composites with lamellar microstructures

    DEFF Research Database (Denmark)

    Piat, R.; Sinchuk, Y.; Vasoya, M.

    2011-01-01

    of lamellar domains. With local ceramic volume fraction and lamella orientation chosen as the design variables, a minimum compliance optimization problem is solved based on topology optimization and finite element methods for metal–ceramic samples with different geometries and boundary conditions....... Micromechanical models are applied for the calculation of the effective elastic properties of the composites. Optimized local lamella orientations and ceramic contents are calculated, and the difference between the initial (specimen with constant ceramic content and orientation) and the optimized designs......Metal–ceramic composites produced by melt infiltration of ceramic preforms are studied in an optimal design context. The ceramic preforms are manufactured through a process of freeze-casting of Al2O3 particle suspension. The microstructure of these composites can be presented as distributions...

  12. Ru complexes of Hoveyda–Grubbs type immobilized on lamellar zeolites: activity in olefin metathesis reactions

    Directory of Open Access Journals (Sweden)

    Hynek Balcar

    2015-11-01

    Full Text Available Hoveyda–Grubbs type catalysts with cationic tags on NHC ligands were linker-free immobilized on the surface of lamellar zeolitic supports (MCM-22, MCM-56, MCM-36 and on mesoporous molecular sieves SBA-15. The activity of prepared hybrid catalysts was tested in olefin metathesis reactions: the activity in ring-closing metathesis of citronellene and N,N-diallyltrifluoroacetamide decreased in the order of support MCM-22 ≈ MCM-56 > SBA-15 > MCM-36; the hybrid catalyst based on SBA-15 was found the most active in self-metathesis of methyl oleate. All catalysts were reusable and exhibited low Ru leaching (− counter anion; in contrast, PF6− counter anion underwent partial decomposition.

  13. Results of topography of the cornea following deep anterior lamellar keratoplasty

    Directory of Open Access Journals (Sweden)

    Ramin Salati

    2004-09-01

    Full Text Available There are no remarkable reports about the topographic characteristics of the cornea following deep anterior lamellar keratoplasty (DLKP. In this study we tried to characterize the corneal topographic patterns following DLKP, and determine the correlations between these patterns with other factors. In this study optical DLPP with Melles technique was performed on 40 keratoconus eyes. Each patient was examined in four separate sessions once preoperatively, and three sessions at 3, 6, and 12 months postoperatively. The corneal topographic pattern of each exam was identified, and its correlations with other factors such as suturing technique were evaluated. The decreases in mean keratometry and mean corneal astigmatism and the conversion of irregular topographic patterns to regular patterns were significant following the operation. There were not any cases of immunologic endothelial rejection. We conclude that DLKP is a safe and predictable surgical treatment in keratoconus eyes.

  14. Lamellar refractive surgery with scanned intrastromal picosecond and femtosecond laser pulses in animal eyes.

    Science.gov (United States)

    Kurtz, R M; Horvath, C; Liu, H H; Krueger, R R; Juhasz, T

    1998-01-01

    To evaluate the use of scanned intrastromal picosecond and femtosecond laser pulses in lamellar refractive surgical procedures. Intrastromal corneal photodisruption was performed in fresh porcine and primate cadaver eyes with a solid-state femtosecond laser. Laser pulses were focused 150 to 200 microns below the epithelial surface and scanned in a spiral pattern to create a plane. A flap was made by scanning an arc pattern from the plane of the spiral to the surface of the cornea. Tissue plane separation was graded using a standard scale, while internal surfaces were analyzed by scanning electron microscopy. Comparison was made to a picosecond laser system using the same delivery system device. Creation of a stromal lenticule for in situ keratomileusis was also demonstrated and compared with both laser systems. For femtosecond pulses, tissue separation was achieved best with pulse energies from 4 to 8 microJ and spot separations from 10-15 microns. Picosecond pulses accomplished less complete separations with pulse energies of 25 microJ and spot separations from 10 to 20 microns. Surface quality corresponded to dissection results, with high-grade dissections resulting in a smooth surface appearance, versus a more irregular surface for low-grade dissections. Although high-grade dissections could be created with picosecond pulses (with optimal parameters) in ex vivo porcine eyes, only femtosecond parameters produced similar results in ex vivo primate eyes. In contrast to previous attempts using picosecond lasers which require additional mechanical dissection, high precision lamellar refractive surgery may be practical with femtosecond laser pulses.

  15. [Reproducibility of femtosecond laser incisions for posterior lamellar keratoplasty in vitro].

    Science.gov (United States)

    Harlfinger, S; Langenbucher, A; Hofmann-Rummelt, C; Seitz, B

    2013-01-01

    In the last decade surgeons have tried to use posterior lamellar keratoplasty (PLAK) in a way that maintains the biomechanical stability of the intact cornea. Femtosecond lasers can be used to cut a lenticle out of the posterior part of the stroma. The purpose of this study was to assess the reproducibility of the generated lenticles. The FEMTEC-Laser (20/10 Perfect Vision, Heidelberg, Germany) was used to perform posterior lamellar dissections. The goal was to assess the real thickness of the graft in comparison to the intended thickness predefined with the laser. The histological preparations were viewed using light microscopy (Olympus microscope). Main outcome measures included difference of intended versus real distance of the horizontal plane from Bowman's layer and quantification of the created bubbles. The intended distance was reached with a precision of 115-160 µm and was constant over the whole length of the lenticle depending on the depth of the laser action. The number and size of the generated bubbles was equal in the different layers. At least one zone of stromal condensation could be found in 88.9% of the corneas and 63% of the corneas showed a partial perforation or minimal lesions of Descemet's membrane. The distance of the two closest bubbles to Descemet's membrane increased in thinner lenticles, i.e. a greater distance from Bowman's layer. No damage occurred due to compression or heat. As the laser generates a reproducible number of bubbles of the same size, precise incisions can be achieved. Thus the femtosecond laser proved to be an accurate tool for PLAK. In the majority of cases a lesion of Descemet's membrane could be found which seems to make the removal of the lenticles easier. A disadvantage is a decreasing probability of a lesion of Descemet's membrane as well as the decreasing precision in thinner lenticles.

  16. Multiscale Simulations of Lamellar PS–PEO Block Copolymers Doped with LiPF6 Ions

    KAUST Repository

    Sethuraman, Vaidyanathan

    2017-06-02

    We report the results of atomistic simulations of the structural equilibrium properties of PS–PEO block copolymer (BCP) melt in the ordered lamellar phase doped with LiPF6 salt. A hybrid simulation strategy, consisting of steps of coarse-graining and inverse coarse-graining, was employed to equilibrate the melt at an atomistic resolution in the ordered phase. We characterize the structural distributions between different atoms/ions and compare the features arising in BCPs against the corresponding behavior in PEO homopolymers for different salt concentrations. In addition, the local structural distributions are characterized in the lamellar phase as a function of distance from the interface. The cation–anion radial distribution functions (RDF) display stronger coordination in the block copolymer melts at high salt concentrations, whereas the trends are reversed for low salt concentrations. Radial distribution functions isolated in the PEO and PS domains demonstrate that the stronger coordination seen in BCPs arises from the influence of both the higher fraction of ions segregated in the PS phase and the influence of interactions in the PS domain. Such a behavior also manifests in the cation–anion clusters, which show a larger fraction of free ions in the BCP. While the average number of free anions (cations) decreases with increasing salt concentration, higher order aggregates of LiPF6 increase with increasing salt concentration. Further, the cation–anion RDFs display spatial heterogeneity, with a stronger cation–anion binding in the interfacial region compared to bulk of the PEO domain.

  17. Ion transport mechanisms in lamellar phases of salt-doped PS-PEO block copolymer electrolytes.

    Science.gov (United States)

    Sethuraman, Vaidyanathan; Mogurampelly, Santosh; Ganesan, Venkat

    2017-11-01

    We use a multiscale simulation strategy to elucidate, at an atomistic level, the mechanisms underlying ion transport in the lamellar phase of polystyrene-polyethylene oxide (PS-PEO) block copolymer (BCP) electrolytes doped with LiPF6 salts. Explicitly, we compare the results obtained for ion transport in the microphase separated block copolymer melts to those for salt-doped PEO homopolymer melts. In addition, we also present results for dynamics of the ions individually in the PEO and PS domains of the BCP melt, and locally as a function of the distance from the lamellar interfaces. When compared to the PEO homopolymer melt, ions were found to exhibit slower dynamics in both the block copolymer (overall) and in the PEO phase of the BCP melt. Such results are shown to arise from the effects of slower polymer segmental dynamics in the BCP melt and the coordination characteristics of the ions. Polymer backbone-ion residence times analyzed as a function of distance from the interface indicate that ions have a larger residence time near the interface compared to that near the bulk of lamella, and demonstrates the influence of the glassy PS blocks and microphase segregation on the ion transport properties. Ion transport mechanisms in BCP melts reveal that there exist five distinct mechanisms for ion transport along the backbone of the chain and exhibit qualitative differences from the behavior in homopolymer melts. We also present results as a function of salt concentration which show that the mean-squared displacements of the ions decrease with increasing salt concentration, and that the ion residence times near the polymer backbone increase with increasing salt concentration.

  18. Dual-purpose corneal tissue for anterior lamellar keratoplasty and Descemet's membrane endothelial keratoplasty.

    Science.gov (United States)

    Menant-Tay, C Larena; Conlon, Ronan; Teja, Salina; Yeung, Season; Teichman, Joshua; Ziai, Setareh; Baig, Kashif

    2016-12-01

    To assess the intraoperative issues and surgical outcomes of preparing a single-donor corneal tissue for same-day use in both deep anterior lamellar keratoplasty (DALK) and Descemet's membrane endothelial keratoplasty (DMEK). Consecutive retrospective case series. Ten eyes of 10 patients who underwent DALK (5 patients) or DMEK (5 patients) surgery using dual-purpose corneal tissue. Five dual-purpose corneoscleral rims were used to prepare tissue for 5 DMEK and 5 DALK procedures. The submerged cornea using backgrounds away technique was first used to harvest the 5 DMEK grafts, and the remaining tissue was used for the 5 DALK grafts. Tissue preparation and operative use occurred on the same day. Tissue preparation challenges, intraoperative complications, and visual recovery were assessed. There were no difficulties in preparing the 5 dual-purpose tissues, and all 10 lamellar transplants were completed successfully. At the 6-month follow-up, the mean best-corrected distance visual acuity improved from 20/250 to 20/80 in the DALK patients, and from 20/300 to 20/25 in the DMEK patients. Postoperative complications after DALK included retained viscoelastic agent at the interface in 1 patient and a double anterior chamber managed with rebubbling in another. After DMEK, a peripheral partial graft detachment occurred in 1 patient and was managed successfully with rebubbling. All corneas demonstrated clarity on slit-lamp examination. Single-donor corneal tissue can be effectively used for both DALK and DMEK, and may represent a more efficient use of corneal tissue. Complications with the preparation of dual-purpose tissue were not encountered. Copyright © 2016 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.

  19. Ion transport mechanisms in lamellar phases of salt-doped PS–PEO block copolymer electrolytes

    KAUST Repository

    Sethuraman, Vaidyanathan

    2017-10-23

    We use a multiscale simulation strategy to elucidate, at an atomistic level, the mechanisms underlying ion transport in the lamellar phase of polystyrene–polyethylene oxide (PS–PEO) block copolymer (BCP) electrolytes doped with LiPF6 salts. Explicitly, we compare the results obtained for ion transport in the microphase separated block copolymer melts to those for salt-doped PEO homopolymer melts. In addition, we also present results for dynamics of the ions individually in the PEO and PS domains of the BCP melt, and locally as a function of the distance from the lamellar interfaces. When compared to the PEO homopolymer melt, ions were found to exhibit slower dynamics in both the block copolymer (overall) and in the PEO phase of the BCP melt. Such results are shown to arise from the effects of slower polymer segmental dynamics in the BCP melt and the coordination characteristics of the ions. Polymer backbone-ion residence times analyzed as a function of distance from the interface indicate that ions have a larger residence time near the interface compared to that near the bulk of lamella, and demonstrates the influence of the glassy PS blocks and microphase segregation on the ion transport properties. Ion transport mechanisms in BCP melts reveal that there exist five distinct mechanisms for ion transport along the backbone of the chain and exhibit qualitative differences from the behavior in homopolymer melts. We also present results as a function of salt concentration which show that the mean-squared displacements of the ions decrease with increasing salt concentration, and that the ion residence times near the polymer backbone increase with increasing salt concentration.

  20. Big-bubble deep anterior lamellar keratoplasty assisted by femtosecond laser in children.

    Science.gov (United States)

    Buzzonetti, Luca; Petrocelli, Gianni; Valente, Paola

    2012-09-01

    To report the early results of big-bubble deep anterior lamellar keratoplasty assisted by femtosecond laser in children. Five eyes of 5 pediatric patients were enrolled in the study; 3 had keratoconus and 2 corneal opacities. An IntraLase 60 KHz femtosecond laser (Abbott Medical Optics, Inc) was used to create mushroom incisions on both donor and recipient corneas. All patients were evaluated for best-corrected visual acuity, spherical equivalent, refractive astigmatism, keratometric astigmatism, mean K value, and corneal thinnest point. The big bubble was always achieved, and all eyes were treated successfully without intraoperative complications. The follow-up was of 10 months. At 10 months (at least 3 months after complete suture removal), the mean postoperative best-corrected visual acuity was 20/30 (range, 20/25 to 20/30), mean spherical equivalent was -1.8 ± 1.2 diopters (D) (range, -0.25 to 1.25 D), mean refractive astigmatism was 1.8 ± 1.4 D (range, 0 to 4.0 D), mean keratometric astigmatism was 5.1 ± 2.1 D (range, 3.5 to 8.59 D), mean K value was 46.2 ± 0.8D, and mean corneal thinnest point was 581 ± 46 μm (range, 511-638 μm). Our early findings suggest that the big-bubble technique in deep anterior lamellar keratoplasty assisted by femtosecond laser is safe and effective also in pediatric patients in the attempt to decrease the rejection percentage, improve the refractive outcome, and then provide an antiamblyopic effect.

  1. Coherent Lamellar Growth of Akimotoite within Enstatite Host at High Pressure and Temperature

    Science.gov (United States)

    Lockridge, J.; Sharp, T. G.; Hu, J.

    2013-12-01

    To constrain models of the rheology and dynamic behavior of subducting oceanic lithosphere within the mantle transition zone, it is important to understand the mechanisms by which the major mineralogical components of the slab transform to their high-pressure polymorphs. Despite being the second most abundant component of the upper mantle, the mechanisms of polymorphic phase transformations in pyroxene remain poorly understood. In subducting oceanic lithosphere, which is colder than the surrounding mantle, akimotoite would be stable relative to majorite and the polymorphic reaction to akimotoite would be kinetically favored over disproportionation reactions to ringwoodite or wadsleyite plus stishovite. There are two transformation mechanisms that have been observed in experiments studying polymorphic transformation of mantle silicates. Heterogeneous nucleation and interface controlled growth is the most commonly observed mechanism, with product phases typically growing as incoherent, granular rims. A second, shear-induced mechanism is characterized by coherent lamellar growth of high-pressure phases on stacking faults within the host grain. Coherent lamellar intergrowth has been observed experimentally in (Mg,Fe)2SiO4 olivine (Kerschhofer 1996, 1998) and within shocked chondritic meteorites for both olivine (Chen et al., 2004) and enstatite (Tomioka and Fujino 1997, 1999). Tomioka (2007) modeled a shear-induced mechanism for the enstatite-akimotoite transition, but this mechanism has not been observed experimentally. We are investigating transformation reactions and kinetics of natural Mg0.9Fe0.1SiO3 enstatite. Within a sample transformed at 20GPa and 1400°C, we observe akimotoite lamellae within the enstatite host. Using transmission electron microscopy, we confirm the coherent, topotaxial relationship between the akimotoite and enstatite as modeled in Tomioka (2007). These findings suggest that shear-induced intracrystalline transformation of enstatite to

  2. Endothelial lamellar keratoplasty using an artificial anterior chamber and a microkeratome.

    Science.gov (United States)

    Behrens, Ashley; Ellis, Kenneth; Li, Li; Sweet, Paula M; Chuck, Roy S

    2003-04-01

    To compare postoperative astigmatic change and graft stability using 2 different donor button diameters in endothelial lamellar keratoplasty to treat corneal endothelial failure. A 200- micro m-thick corneal flap keratectomy was performed in human donor corneoscleral rims (n = 20; 10 donors and 10 recipients) using an artificial anterior chamber and a manual microkeratome (ALTK System; Moria USA, Doylestown, Pa). After flap reflection, stromal bed trephination was performed to obtain a disc consisting of posterior stroma, Descemet membrane, and endothelium. Host beds of 7.0 mm and 7.25-mm (n = 5) or 7.50-mm (n = 5) donor buttons were obtained using a freehand trephine. The graft was secured with 8 interrupted sutures (10-0 nylon) in the stromal bed. The flap was sutured with 3 interrupted sutures. Transplanted corneas were submitted to increasing intrachamber pressures to detect graft stability, and preoperative and postoperative videokeratographic data were recorded to assess astigmatic change. The mean (SD) postoperative astigmatic change was 1.14 (3.17) diopters (D) in the 7.25-mm donor button group and 2.27 (1.77) D in the 7.50-mm donor button group (P =.69). Mean (SD) resisted pressures of 75.4 (44.81) mm Hg and 100.4 (46.86) mm Hg were observed in the 7.25-mm and 7.50-mm groups, respectively (P =.54). Both donor button sizes exhibited similar graft stability and astigmatic postoperative change in this experimental model. As endothelial lamellar keratoplasty becomes further developed as a clinical alternative to penetrating keratoplasty, this laboratory model system should be useful in evaluating different mechanical factors that contribute to graft success.

  3. Lamellar Thickness and Stretching Temperature Dependency of Cavitation in Semicrystalline Polymers

    Science.gov (United States)

    Wang, Yaotao; Jiang, Zhiyong; Fu, Lianlian; Lu, Ying; Men, Yongfeng

    2014-01-01

    Polybutene-1 (PB-1), a typical semicrystalline polymer, in its stable form I shows a peculiar temperature dependent strain-whitening behavior when being stretched at temperatures in between room temperature and melting temperature of the crystallites where the extent of strain-whitening weakens with the increasing of stretching temperature reaching a minima value followed by an increase at higher stretching temperatures. Correspondingly, a stronger strain-hardening phenomenon was observed at higher temperatures. The strain-whitening phenomenon in semicrystalline polymers has its origin of cavitation process during stretching. In this work, the effect of crystalline lamellar thickness and stretching temperature on the cavitation process in PB-1 has been investigated by means of combined synchrotron ultrasmall-angle and wide-angle X-ray scattering techniques. Three modes of cavitation during the stretching process can be identified, namely “no cavitation” for the quenched sample with the thinnest lamellae where only shear yielding occurred, “cavitation with reorientation” for the samples stretched at lower temperatures and samples with thicker lamellae, and “cavitation without reorientation” for samples with thinner lamellae stretched at higher temperatures. The mode “cavitation with reorientation” occurs before yield point where the plate-like cavities start to be generated within the lamellar stacks with normal perpendicular to the stretching direction due to the blocky substructure of the crystalline lamellae and reorient gradually to the stretching direction after strain-hardening. The mode of “cavitation without reorientation” appears after yield point where ellipsoidal shaped cavities are generated in those lamellae stacks with normal parallel to the stretching direction followed by an improvement of their orientation at larger strains. X-ray diffraction results reveal a much improved crystalline orientation for samples with thinner lamellae

  4. The estimate of permittivity of anisotropic composites with lamellar inclusions by the self-assessment method

    Directory of Open Access Journals (Sweden)

    V. S. Zarubin

    2015-01-01

    Full Text Available Composites are widely used as structural or thermal protection materials; they are used as well as functional materials in a large number of different electrical devices and as dielectrics. This composite has one of the most important characteristics the relative permittivity. It depends primarily on the dielectric properties of the inclusions and the matrix as well as the shape and volume content of the inclusions.In this paper, a mathematical model of the interaction of the electrostatic fields in an isotropic plate and in the surrounding homogeneous anisotropic medium is constructed. This model describes the dielectric properties of the composite with such inclusions. A variant of the same orientation of lamellar inclusions is considered, which leads to the special case of anisotropy of the dielectric properties of the composite that has transverse isotropy towards the direction perpendicular to the inclusions. The shape of inclusions is represented as an oblate ellipsoid of revolution (spheroid. Transformation of the differential equation describing the distribution of the electric potential transversely to isotropic medium surrounding the spheroidal inclusion, to the Laplace equation with the subsequent transition from the initial spheroid to the given ellipsoid of rotation allows us to apply the self-assessment method for the determination of the dielectric properties of the composite. This method equates the result of averaging the perturbation of the electrostatic field in the inclusions and the matrix particles towards the unperturbed fields in the environment to zero.The constructed mathematical model allows us to determine the electrostatic field disturbance in the inclusions and the matrix particles towards the unperturbed field given in the environment at a distance from the inclusions and the matrix particles, much larger than their characteristic dimensions. By averaging the perturbation of the electrostatic field in all the

  5. Deep lamellar keratoplasty by intracorneal dissection: a prospective clinical and confocal microscopic study.

    Science.gov (United States)

    Marchini, Giorgio; Mastropasqua, Leonardo; Pedrotti, Emilio; Nubile, Mario; Ciancaglini, Marco; Sbabo, Arianna

    2006-08-01

    To evaluate the clinical findings, visual outcomes, and confocal microscopic corneal features of a surgical technique for manual deep lamellar keratoplasty (DLKP) with intentional sparing of the most posterior stroma. Noncomparative, prospective, 12-month interventional study. Forty-six eyes of 45 patients who had corneal pathologic features without endothelial abnormalities and requiring corneal graft were treated by DLKP by manual stromal delamination. They were examined clinically after surgery and using in vivo confocal microscopy at 2 weeks and 1, 3, 6, and 12 months. The surgical technique consisted of an intracorneal deep manual stromal dissection through a 4-mm limbal incision at 50 mum from Descemet's membrane (DM). After trephination, an endothelial free graft was sutured. Topographic parameters, interface depth and reflectivity, and anterior and postinterface keratocyte density; visual acuity was correlated with these parameters. Two eyes had rupture of the DM. Two eyes that had delayed epithelial healing because of graft override with stromal inflammation underwent a second surgery (penetrating keratoplasty). Mean uncorrected logarithm of the minimum angle of resolution (logMAR) uncorrected visual acuity and logMAR best-corrected visual acuity (BCVA) improved from preoperative values (1.342+/-0.239 and 0.923+/-0.226, respectively) to 0.421+/-0.122 and 0.104+/-0.068, respectively, at 12 months. Mean topographic astigmatism was 3.09+/-1.30 diopters (D) at 3 months after suture adjustment, and 2.87+/-0.92 D at 12 months after suture removal. Average interface depth was 64.2+/-6.7 microm at 15 days and showed no significant changes up to 12 months. Mean interface reflectivity was highest at 15 days (95.5+/-15.7 light reflectance units [LRU]) and showed a progressive decrease over time of 55.3+/-8.7 LRU at 12 months. A significant negative correlation was observed between BCVA and topographic astigmatism up to 1 month and between BCVA and interface

  6. The effect of octyl glucoside on the lamellar phase of diluted C12E4 and alcohol systems.

    Science.gov (United States)

    Granizo, Noelia; Thunig, Christine; Valiente, Mercedes

    2004-05-15

    A systematic study on phase behavior of the mixture of nonionic surfactants with alcohols at 30.0+/-0.1 degrees C was carried out. The total surfactant concentration was kept to 0.1 M varying the mole ratio of n-octyl beta-d-glucopyranoside (OG) and tetraethylene glycol monododecyl ether. Two uniphasic regions were found, the lamellar phase at low OG mole fraction and micelles at high OG mole fraction. The presence of OG favors the lamellae-micelle transition. Alkanols and benzyl alcohol were used as cosurfactants. The more hydrophobic alcohols (octanol and decanol) increase the OG content in the mixed bilayers. On the contrary, benzyl alcohol is not as favorable to the OG incorporation in the lamellar phase as in the mixed micelles. The L(3) phase has only been found as a uniphasic region with hexanol.

  7. Crystallization in organo-mineral micro-domains in the crossed-lamellar layer of Nerita undata (Gastropoda, Neritopsina).

    Science.gov (United States)

    Nouet, Julius; Baronnet, Alain; Howard, Lauren

    2012-02-01

    Crossed-lamellar shell microstructure consists of a sophisticated arrangement of interspersed lamellae, which is very commonly found in Gastropoda or Bivalvia shell layers. Its smallest constitutive microstructural units are usually described as sub-micrometric fibers, or rods, and form very ordered and regular patterns. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) imaging confirms the presence of even smaller building units in the form of organo-mineral granules, and we further investigate their internal structure within aragonite crossed-lamellar internal layer of Nerita undata (Gastropoda, Neritopsina) shell. Their coalescence may have controlled anisotropically the propagation of the crystallographic coherence through this complex microstructure, as suggested by the propagation of the microtwinning pattern between neighboring granules. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Clinical observation of corneal lamellar debridement combined with sutureless amniotic membrane transplantation for the treatment of superficial fungal keratitis

    Directory of Open Access Journals (Sweden)

    Huang Zhang

    2014-09-01

    Full Text Available AIM:To evaluate the clinical efficacy of corneal lamellar debridement combined with sutureless amniotic membrane transplantation for the treatment of superficial fungal keratitis.METHODS:Totally 22 cases(22 eyeswith superficial fungal keratitis were referred to our hospital from April 2012 to October 2013. The patients with persistent cornea ulcer after treatment of local and systemic antifungal drugs underwent corneal lamellar debridement combined with sutureless amniotic membrane transplantation, and the recipient bed was covered with an amniotic membrane using fibrin sealant during the operation. All patients were still given topical antifungal therapy for 1-2mo after operation. The followed-up time was 3mo or above. We observed the corneal healing and amniotic membrane adhesion by split lamp microscope, and investigated the transformation of amniotic membrane and fungal infection recurrence with confocal microscope. RESULTS: Corneal edema and anterior chamber reaction of 21 patients disappeared gradually, and no amniotic membrane graft dissolved and shed off within 1-2wk postoperatively. Two weeks after operation, the graft integrated into the corneal and the corneal wounds' thickness increased gradually, the corneal epithelium reconstructed and corneas became clear. Four weeks after operation, the corneal scarring developed gradually and fluorescence staining was negative. Nineteen cases' amniotic membranes that adhered with the cornea dissolved 4wk after operation. There were different degrees of corneal nebula or macula remained 3mo postoperatively. All patients' vision improved in varying degrees, except in 1 case with fungal keratitis who had been cured by lamellar keratoplasty.CONCLUSION:Corneal lamellar debridement combined with sutureless amniotic membrane transplantation can effectively remove the foci of inflammation, improve the local efficacy, shorten the operation time, relieve the postoperative reaction, and promote cornea

  9. Preparation of a self-supporting cell architecture mimic by water channel confined photocrosslinking within a lamellar structured hydrogel.

    Energy Technology Data Exchange (ETDEWEB)

    Grubjesic, S.; Lee, B.; Seifert, S.; Firestone, M. A. (Materials Science Division); ( XSD)

    2011-01-01

    A self-supporting biomimetic chemical hydrogel that can be reversibly swollen in water is described. An aqueous dispersion of a diacrylate end-derivatized PEO-PPO-PEO macromer, a saturated phospholipid, and a zwitterionic co-surfactant self-assembles into a multilamellar-structured physical gel at room temperature as determined by SAXS. The addition of a water soluble PEGDA co-monomer and photoinitiator within the water layers does not alter the self-assembled structure. ATR/FT-IR spectroscopy reveals that photoirradiation initiates the crosslinking between the acrylate end groups on the macromer with the PEGDA, forming a polymeric network within the aqueous domains. The primitive cytoskeleton mimic serves to stabilize the amphiphile bilayer, converting the physical gel into an elastic self-supporting chemical gel. Storage under ambient conditions causes dehydration of the hydrogel to 5 wt % water which can be reversed by swelling in water. The fully water swollen gel (85 wt % water) remains self-supporting but converts to a non-lamellar structure. As water is lost the chemical gel regains its lamellar structure. Incubation of the hydrogel in nonpolar organic solvents that do not dissolve the uncrosslinked lipid component (hexane) allow for swelling without loss of structural integrity. Chloroform, which readily solubilizes the lipid, causes irreversible loss of the lamellar structure.

  10. The Molecular Structure of Human Red Blood Cell Membranes from Highly Oriented, Solid Supported Multi-Lamellar Membranes

    Science.gov (United States)

    Himbert, Sebastian; Alsop, Richard J.; Rose, Markus; Hertz, Laura; Dhaliwal, Alexander; Moran-Mirabal, Jose M.; Verschoor, Chris P.; Bowdish, Dawn M. E.; Kaestner, Lars; Wagner, Christian; Rheinstädter, Maikel C.

    2017-01-01

    We prepared highly oriented, multi-lamellar stacks of human red blood cell (RBC) membranes applied on silicon wafers. RBC ghosts were prepared by hemolysis and applied onto functionalized silicon chips and annealed into multi-lamellar RBC membranes. High resolution X-ray diffraction was used to determine the molecular structure of the stacked membranes. We present direct experimental evidence that these RBC membranes consist of nanometer sized domains of integral coiled-coil peptides, as well as liquid ordered (lo) and liquid disordered (ld) lipids. Lamellar spacings, membrane and hydration water layer thicknesses, areas per lipid tail and domain sizes were determined. The common drug aspirin was added to the RBC membranes and found to interact with RBC membranes and preferably partition in the head group region of the lo domain leading to a fluidification of the membranes, i.e., a thinning of the bilayers and an increase in lipid tail spacing. Our results further support current models of RBC membranes as patchy structures and provide unprecedented structural details of the molecular organization in the different domains.

  11. Observation on ultrastructure and histopathology of cornea following femtosecond laser-assisted deep lamellar keratoplasty for acute corneal alkaline burns

    Directory of Open Access Journals (Sweden)

    Wen-Jing Li

    2016-04-01

    Full Text Available AIM: To demonstrate the changes in ultrastructure and histopathology of the cornea in acute corneal alkaline burns after femtosecond laser-assisted deep lamellar keratoplasty. METHODS: The New Zealand white rabbits treated with alkaline corneal burn were randomized into two groups, Group A (16 eyes with femtosecond laser-assisted deep lamellar keratoplasty 24h after burn and Group B (16 eyes without keratoplasty as controls. All eyes were evaluated with transmission electron microscopy (TEM at 1, 2, 3, and 4wk follow-up, then all corneas were tested by hematoxylin and eosin staining histology. RESULTS: The corneal grafts in Group A were transparent, while those in Group B showed corneal stromal edema and loosely arranged collagen fibers. One week after treatment, TEM revealed the intercellular desmosomes in the epithelial layers and intact non-dissolving nuclei in Group A. At week 4, the center of the corneas in Group A was transparent with regularly arranged collagen fibers and fibroblasts in the stroma. In Group B, squamous cells were observed on the corneal surface and some epithelial cells were detached. CONCLUSION: Femtosecond laser-assisted deep lamellar keratoplasty can suppress inflammatory responses, prevent toxic substance-induced injury to the corneal endothelium and inner tissues with quicker recovery and better visual outcomes.

  12. Growth and structure of lamellar mixed crystals of octacalcium phosphate and apatite in a model system of enamel formation

    Science.gov (United States)

    Iijima, Mayumi; Tohda, Hisako; Moriwaki, Yutaka

    1992-02-01

    Lamellar mixed crystals of octacalcium phosphate (OCP) and apatite were synthesized in a model system of enamel formation in the presence of 1 ppm F - at 37°C and at pH 6.5. The crystal has long and thin plate-like morphology and contained a distinct OCP lamella in the center of the apatite matrix. The thickness of the OCP lamella in the a-axis direction is one to several unit cells. Some apatite crystals embed a central layer instead of the distinct OCP lamella. The OCP lamella and the central layer are parallel to the (100) plane of the apatite, while the c-axis of the OCP is parallel to the c-axis of the apatite. Analysis suggests that (1) F - causes the growth of apatite on OCP and regulates the formation of the lamellar mixed crystals of OCP and apatite, (2) the OCP lamella acts as a template for the subsequent epitaxial growth of apatite, and (3) the lamellar mixed crystals grow mainly in the c-axis direction of both the OCP and apatite. These results strongly support the idea that enamel crystals take a thin and long ribbon-like morphology when the initially formed OCP acts as a template for the subsequent growth of apatite in the enamel formation.

  13. Lamellar Diblock Copolymer Thin Films during Solvent Vapor Annealing Studied by GISAXS: Different Behavior of Parallel and Perpendicular Lamellae.

    Science.gov (United States)

    Zhang, Jianqi; Posselt, Dorthe; Smilgies, Detlef-M; Perlich, Jan; Kyriakos, Konstantinos; Jaksch, Sebastian; Papadakis, Christine M

    2014-08-26

    The reorientation of lamellae and the dependence of the lamellar spacing, Dlam, on polymer volume fraction, ϕP, Dlam ∝ ϕP(-β), in diblock copolymer thin films during solvent vapor annealing (SVA) are examined by combining white light interferometry (WLI) and grazing-incidence small-angle X-ray scattering (GISAXS). A thin film of lamellae-forming poly(styrene-b-butadiene) prepared by spin-coating features lamellae of different orientations with the lamellar spacing depending on orientation. During annealing with ethyl acetate (EAC) vapor, it is found that perpendicular lamellae behave differently from parallel ones, which is due to the fact that their initial lamellar thicknesses differ strongly. Quantitatively, the swelling process is composed of three regimes and the drying process of two regimes. The first two regimes of swelling are associated with a significant structural rearrangement of the lamellae; i.e., the lamellae first become thicker, and then perpendicular and randomly oriented lamellae vanish, which results in a purely parallel orientation at the end of the swelling process. The rearrangement is attributed to the increase of mobility of the polymer chains imparted by the solvent and to a decrease of total free energy of the thin film. In the third regime of swelling, the scaling exponent is found to be β = -0.32. During drying, the deswelling is nonaffine which may be a consequence of the increase of nonfavorable segmental interactions as the solvent is removed.

  14. Evaluation of therapeutic deep anterior lamellar keratoplasty in acute ocular chemical burns.

    Science.gov (United States)

    Singh, G; Singh Bhinder, H

    2008-01-01

    To evaluate the role of deep anterior lamellar keratoplasty (DALK) in acute ocular chemical burns. The study was conducted in 50 eyes of 50 patients (24 male, 26 female) with average age of 38.3+/-14.3 years. DALK in 5 eyes (10%), DALK with quadrant conjunctivo-limbal graft in 25 eyes (50%), and DALK with amniotic membrane in 20 eyes (40%) were performed along with conventional medical therapy. Controls who were matched in all respects (50 eyes) were given medical therapy only as they refused surgical intervention. Follow-up of cases ranged from 6 to 48 months (mean 21.5+/-14.18 months). Forty-three eyes (86%) could be restored with clear cornea as compared to 6% in control group. The visual acuity improvement was seen in 100% with good score (0.49+/-1.46) in DALK group as compared to 18% with low score (0.03+/-0.01) in control group (pburns of grade IV (pburns.

  15. Intraoperative review of different bubble types formed during pneumodissection (big-bubble) deep anterior lamellar keratoplasty.

    Science.gov (United States)

    Goweida, Mohamed Bahgat Badawi

    2015-06-01

    To evaluate the preoperative factors and intraoperative complications of the 2 bubble types formed during big-bubble deep anterior lamellar keratoplasty (DALK). This is a retrospective review of medical records of a series of patients who underwent DALK using the big-bubble technique from September 2009 to March 2014. A total of 134 eyes were included in this study-89 eyes with advanced keratoconus, 35 eyes with post-microbial keratitis corneal scars, 8 eyes with stromal dystrophies, and 2 eyes with post-laser in situ keratomileusis ectasia. A type 1 bubble (white margin) was achieved in 56 eyes (41.8%), whereas a type 2 bubble (clear margin) was formed in 14 eyes (10.4%) and a mixed bubble was formed in 2 eyes (1.5%). Big-bubble formation failed in 62 (46.3%). All eyes with the type 1 bubble were completed as DALK; microperforation occurred in 4 eyes. Twelve of 14 eyes with the type 2 bubble were converted to penetrating keratoplasty because of large perforations. The type 2 bubble is more likely to form in elderly patients and those with deep corneal scars and thin corneas. Because of the high rate of conversion to penetrating keratoplasty, better surgical strategies may be needed to manage type 2 bubbles.

  16. Bilateral diffuse lamellar keratitis triggered by permanent eyeliner tattoo treatment: A case report.

    Science.gov (United States)

    Lu, Cheng-Wei; Liu, Xiu-Fen; Zhou, Dan-Dan; Kong, Yu-Jiao; Qi, Xiao-Feng; Liu, Tao-Tao; Qu, Ting; Pan, Xiao-Tao; Liu, Cong; Hao, Ji-Long

    2017-07-01

    Diffuse lamellar keratitis (DLK) is a sterile inflammation of the cornea, which may occur after laser-assisted in situ keratomileusis (LASIK) surgery. Little is known about the association of DLK with permanent eyeliner tattoo. The present case report describes the case of a 37-year-old Chinese woman who developed severe foreign body sensation in both eyes 1 week after receiving bilateral permanent eyeliner tattoo treatment. The patient had received bilateral LASIK surgery 10 years previously. Slit-lamp biomicroscopy revealed diffused granular infiltrates precipitated around the edge of the corneal flaps in both eyes. After topical treatment, DLK persisted. Therefore, the patient underwent surgery to remove the corneal epithelium around the DLK lesion. There was no recurrence of the disease during the 3-month observation period. To our knowledge, this is the first case report describing a case of late-onset of DLK that was triggered by permanent eyeliner tattoo. Doctors should be aware of the diagnosis and treatment of this complication associated with the application of permanent eyeliner tattoo as the popularity of this cosmetic procedure increases.

  17. A novel method in preparation of acellularporcine corneal stroma tissue for lamellar keratoplasty.

    Science.gov (United States)

    Shao, Yi; Tang, Jing; Zhou, Yueping; Qu, Yangluowa; He, Hui; Liu, Qiuping; Tan, Gang; Li, Wei; Liu, Zuguo

    2015-01-01

    Our objective was to develop a novel lamellar cornealbiomaterial for corneal reconstruction.Theporcine acellular corneal stroma discs (ACSDs) were prepared from de-epithelized fresh porcine corneas (DFPCs) by incubation with 100% fresh human serum and additional electrophoresis at 4°C. Such manipulation removed theanterior corneal stromal cells without residual of DNA content and α-Galantigen. Human serum decellularizing activity on porcineanterior corneal stroma cells is through apoptosis, and associated with the presence of α-Gal epitopes in anterior stroma. ACSDs displayed similar optical, biomechanical properties and ultrastructure to DFPCs, and showed good histocompatibility in rabbit corneal stromal pockets and anterior chamber. Rabbit corneallamellar keratoplasty (LKP) using ACSDs showed no rejection and high transparency of cornea at 2 months after surgery. In vivo confocal laser scanning microscopy and immunostaining analysis showed complete re-epithelization and stromal cell in growth of ACSDs without inflammatory cell infiltration, new blood vessel ingrowth and excessive wound healing. In conclusion, this novel decellularization method may be valuable for preparation of xenogenic corneal tissue for clinical application, ACSDs resulted from this method may be served as a matrix equivalent for LKP in corneal xenotransplantation.

  18. Randomized Trial Comparing Amniotic Membrane Transplantation with Lamellar Corneal Graft for the Treatment of Corneal Thinning.

    Science.gov (United States)

    de Farias, Charles C; Allemann, Norma; Gomes, José Á P

    2016-04-01

    There are few studies comparing different surgical procedures for the treatment of corneal thinning. Lamellar corneal transplantation (LCT) has been reported to be efficient, but its results can be jeopardized by allograft rejection, opacification, or high astigmatism. Amniotic membrane transplantation (AMT) has been considered a good alternative, but it is not as resistant as LCT and the tissue can be reabsorbed after surgery. A prospective, randomized, interventional, and comparative study of consecutive patients with corneal thinning over 6 months was performed. Ophthalmological examination was performed before transplant surgery and then repeated 1, 7, 15, 30, 90, and 180 days after surgery and ultrasound biomicroscopy was performed before and then 30, 90, and 180 days after surgery to assess corneal thinning. Herpes simplex infection was the main cause of corneal thinning (9 eyes), followed by surgery (cataract, glaucoma, 5 cases), rheumatoid arthritis (1), chemical burn (1), perforating trauma (1), previous band keratopathy treatment (1), and Stevens-Johnson syndrome (1). Although all patients showed significant increase in final thickness in the area of thinning, it was higher in those submitted to LCT at 180 days postoperatively. Regardless of the surgical technique, all patients showed epithelialization. Patients undergoing AMT showed an 89% decrease in neovascularization. Final corrected distance visual acuity was better in patients submitted to AMT. LCT proved to be the best option for treating corneal thinning. AMT represents an alternative that allows good visual recovery but does not restore corneal thickness as efficiently as LCT.

  19. "Tuck In" Lamellar Keratoplasty (TILK) for corneal ectasias involving corneal periphery.

    Science.gov (United States)

    Kaushal, S; Jhanji, V; Sharma, N; Tandon, R; Titiyal, J S; Vajpayee, R B

    2008-02-01

    Evaluation of a new surgical technique for the management of corneal ectasia with peripheral corneal involvement. Twelve eyes of 12 patients with corneal ectasias and peripheral corneal thinning requiring surgical intervention, including eight patients with combined keratoconus and PMD and four patients of keratoglobus, were enrolled for the study in a tertiary care hospital. All patients were contact lens intolerant and had a best corrected visual acuity (BCVA) Keratoplasty (TILK) that included a central lamellar keratoplasty with intrastromal tucking of the peripheral flange was performed in these patients. The main outcome measures analysed were uncorrected visual acuity (UCVA), BCVA, keratometry, refractive status and time for epithelial healing. At the last follow-up (mean: 1.7 years (range 13-48 months)), six patients (50.0%) had BCVA >/=20/60, and all patients had BCVA >/=20/80. The mean keratometry decreased from 57.54 (SD 6.89) D preoperatively to 46.36 (2.39) D (p = 0.003), and the mean spherical equivalent (SEQ) refractive error decreased from -7.8 (4.6) D preoperatively to 1.23 (1.88) D (p = 0.007). A significant decrease was also seen in mean refractive astigmatism which decreased from 5.93 (3.06) D preoperatively to 3.23 (1.14) D (p = 0.037). Our technique of TILK is an effective surgical modality for the management of ectatic corneal dystrophies with peripheral corneal thinning.

  20. Factors Predicting Refractive Outcomes After Deep Anterior Lamellar Keratoplasty in Keratoconus.

    Science.gov (United States)

    Feizi, Sepehr; Javadi, Mohammad Ali

    2015-10-01

    To determine the factors that predict refraction, mean keratometry, and keratometric astigmatism after deep anterior lamellar keratoplasty (DALK) in keratoconus. Consecutive interventional case series. This study enrolled 194 consecutive eyes of 181 patients with keratoconus who underwent DALK using the big-bubble technique. Indications for surgery included contact lens intolerance or poor corrected visual acuity. Univariate analyses and analysis of covariance were used to investigate recipient-, surgical-, and postoperative-related variables capable of predicting refractive outcomes, including mean keratometry, keratometric astigmatism, and spherical equivalent refraction. The mean patient age was 27.9 ± 8.2 years, and the patients were followed for 35.9 ± 18.2 months postoperatively. Preoperative mean keratometry (P = .007), time interval from surgery to running suture removal (P = .01), and suture-tract vascularization (P = .04) significantly influenced postoperative mean keratometry. Vitreous length predicted postoperative spherical equivalent (P = .03). Postoperative keratometric astigmatism failed to demonstrate any significant correlation with the preoperative, surgical, and postoperative variables. Postoperative refractive outcomes did not change relative to patient age and sex, central and peripheral corneal thickness, recipient trephination size, surgical technique (big-bubble vs manual dissection DALK), duration of steroid administration, and elevated intraocular pressure. Keratoconus patients with an elongated posterior segment and/or steep corneas should be informed of the need for postoperative optical correction after DALK. Running suture removal should be postponed for as long as possible if there is no suture-related complication. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Surgical technique for graft exchange after big-bubble deep anterior lamellar keratoplasty.

    Science.gov (United States)

    Scorcia, Vincenzo; Beltz, Jacqueline; Lucisano, Andrea; Scorcia, Giovanni; Busin, Massimo

    2015-04-01

    The aim of this study was to describe a surgical technique for repeat deep anterior lamellar keratoplasty (DALK) by baring Descemet membrane again in eyes affected by stromal opacity of the donor lamella. Repeat DALK was performed in 5 eyes of 5 patients affected by central stromal opacity not involving the endothelium; indications for repeat surgery were postbacterial or postherpetic corneal scars (n = 3), postphotorefractive keratectomy haze (n = 1), and recurrence of granular dystrophy (n = 1). The surgical procedure consisted of the following: (1) superficial trephination, 250 μm in depth, on the original peripheral scar; (2) blunt detachment of the donor graft completed by means of corneal forceps; (3) apposition of the new lamella. Best spectacle-corrected visual acuity, topographic astigmatism, and endothelial cell density were evaluated preoperatively, as well as 3, 6, 9, 12, and 18 months after surgery. At the latest follow-up examination, with all sutures removed from all eyes, the best spectacle-corrected visual acuity was 20/30 or better in all cases with 3 eyes achieving 20/20. Postoperative refractive astigmatism averaged 3.0 ± 1.2 diopters (mean ± SD); endothelial cell density was not significantly affected by surgery. Repeat DALK is effective in removing diseased corneal stroma while keeping the recipient endothelium unaffected; the procedure is simple and does not require pneumatic dissection, thus eliminating the most challenging surgical step; postoperative visual recovery does not differ from that experienced after primary DALK.

  2. Evaluation of different types of lamellar keratoplasty for treatment of peripheral corneal perforation.

    Science.gov (United States)

    Huang, Ting; Wang, Yujuan; Ji, Jianping; Gao, Na; Chen, Jiaqi

    2008-08-01

    To discuss the efficacy and visual outcomes of different types of lamellar keratoplasty (LK) for the treatment of peripheral corneal perforation. Sixty patients (67 eyes) with peripheral corneal perforation underwent semilunar LK (16 eyes), crescentic LK (12 eyes), biconvex LK (13 eyes), annular LK (11 eyes) and total LK (15 eyes) respectively. The applied type of LK for each involved eye was decided by different sizes and shapes of corneal ulceration and perforation. Postoperative visual acuity (VA), corneal astigmatism and postoperative complications were studied during a 7- to 21-month follow-up. VA showed no statistical difference preoperatively (P = 0.18), but it was statistically different postoperatively (P astigmatism in different types of LK was statistically different (P astigmatism, while biconvex LK had the highest. The main postoperative complications were leakage at the graft-host interface, graft rejection and initial disease recurrence. LK is an effective procedure in eyes with peripheral corneal perforation. Different sizes and shapes of LK can influence postoperative VA due to different degrees of astigmatism. Yet postoperative astigmatism can be reduced by making well-matched grafts and preserving the uninvolved tissue to the largest extent.

  3. Comparison of femtosecond laser-assisted descemetic and predescemetic lamellar keratoplasty for keratoconus

    Directory of Open Access Journals (Sweden)

    Yan Lu

    2017-01-01

    Full Text Available Purpose: The purpose of this study is to compare the outcomes following femtosecond laser-assisted deep anterior lamellar keratoplasty (DALK with 75% of stromal dissection (predescemetic group and femtosecond laser-assisted DALK using big-bubble technique with total stromal resection (descemetic group for the treatment of keratoconus. Subjects and Methods: Twenty eyes of 17 patients with keratoconus were studied. There were 10 eyes of 9 patients in predescemetic group and 10 eyes of 8 patients in descemetic group. The postoperative best-corrected visual acuity (BCVA, manifest refraction, keratometry, endothelial cell density (ECD, and central corneal thickness (CCT were analyzed. Results: All surgeries were performed uneventfully. At 1 year after surgery, the BCVA, corneal astigmatism, keratometry, CCT, and ECD between two groups were not statistically significant (all P > 0.05. However, the mean manifest refraction was −9.43 ± 7.44 diopter (D and −1.03 ± 1.13D in predescemetic and descemetic groups, respectively, which was statistically significant between two groups (P < 0.05. Conclusions: The results of BCVA and corneal astigmatism, keratometry, ECD, and CCT were comparable between two groups. However, the mean postoperative manifest refraction was lower in descemetic group.

  4. Deep anterior lamellar keratoplasty for the treatment of stromal corneal dystrophies.

    Science.gov (United States)

    Unal, Mustafa; Arslan, Osman S; Atalay, Eray; Mangan, Mehmet S; Bilgin, Ahmet B

    2013-03-01

    To report the perioperative complications and clinical outcomes after deep anterior lamellar keratoplasty (DALK) using the big bubble technique in eyes with stromal corneal dystrophies. Seventy-four eyes of 65 patients who underwent DALK for stromal corneal dystrophies were evaluated in this retrospective interventional case series study. Main outcome measures were intraoperative and postoperative complications, postoperative uncorrected visual acuity, best spectacle-corrected visual acuity, spherical equivalent refraction, and topographic astigmatism. There were 44 eyes with macular corneal dystrophy, 18 eyes with lattice dystrophy, and 12 eyes with granular dystrophy. DALK was completed in 69 cases (94.6%). Descemet membrane microperforations occurred in 6 eyes (8.7%). The mean follow-up period was 43.5 ± 23.9 months, ranging from 12 to 96 months. Postoperative best spectacle-corrected visual acuity of 0.5 or better was present in 52 of 69 eyes (75.4%). There were 3 episodes of stromal graft rejection, which responded to topical therapy. Lattice dystrophy recurred in 6 eyes (35.3%). DALK using the big bubble technique is an effective procedure in the treatment of patients with corneal stromal dystrophies. Recurrence of lattice dystrophy was relatively high.

  5. Comparative study of keratoconus between Anwar's deep anterior lamellar keratoplasty versus converted penetrating keratoplasty.

    Science.gov (United States)

    Donoso, R; Díaz, C; Villavicencio, P

    2015-06-01

    To compare outcomes between penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK) in patients with keratoconus. Retrospective cohort study. Data of 90 DALK and 49 procedures from conversion to PK, performed by a single surgeon (R.D.) from 2006 to 2011 were analysed. Outcomes on corrected distance visual acuity (BCVA), astigmatism, time to first refraction, pachymetry, endothelial count cell, and postoperative complications were compared between these groups. The mean age of the patients who underwent DALK and PK was 28.2 and 31.7 years, respectively (P=.17). The mean follow up for DALK and for the PK group was 14.7 and 19.4 months, respectively (P=.13). There was no significant difference between PK and DALK groups in the mean postoperative for: BCVA (LogMAR) (0.17 vs. 0.17; P=.59); refractive astigmatism (-3.19 vs.-3.01 diopters; P=.65), and time for the first subjective refraction (60.5 versus 68 days; P=.50). Main postoperative complications were 8% of endothelial rejection in PK group and 10% of deep stromal vascularization in DALK group. The only differences in postoperative results between groups were stromal neovascularization in DALK group and endothelial rejection in PK group. DALK should be considered as the first option when keratoplasty is indicated in keratoconus. Copyright © 2013 Sociedad Española de Oftalmología. Published by Elsevier España, S.L.U. All rights reserved.

  6. Intraoperative videokeratography in penetrating keratoplasty and excimer laser-assisted lamellar keratoplasty for keratoconus.

    Science.gov (United States)

    Spadea, Leopoldo; Fiasca, Arianna; Federici, Simone

    2010-09-01

    To evaluate the usefulness of intraoperative computerized corneal topographic data in excimer laser-assisted lamellar keratoplasty (ELLK) and penetrating keratoplasty (PK). Prospective, comparative, interventional case series. Intra- and postoperative videokeratography (Keratron Scout) evaluation was performed on 30 eyes of 30 consecutive patients affected by keratoconus (16 men and 14 women; mean age 32.63±8.02 years) submitted to ELLK (15 eyes) using 16 interrupted 10-0 nylon stitches or to PK (15 eyes) using a 12-bite 10-0 nylon double-running continuous suture. In the ELLK group, the mean intraoperative keratometric astigmatism was 12.06±4.86 diopters (D), which changed to 5.19±2.51 D after topography-guided intraoperative suture adjustment. In the PK group, intraoperative keratometric astigmatism was 10.18±3.88 D, which changed to 3.49±0.41 D. After 24 months (sutures out), the mean videokeratographic keratometric astigmatism was 3.35±1.96 D in the ELLK group and 3.37±0.92 D in the PK group. The Alpins method of vector analysis showed some significant changes especially in the ELLK group. In keratoplasty surgery, videokeratography is useful for suture adjustment. In the PK group, using a double-running suture technique, the postoperative astigmatism (after all sutures were removed) was similar to the astigmatism measured intraoperatively by videokeratography. Copyright 2010, SLACK Incorporated.

  7. Structure simulation into a lamellar supramolecular network and calculation of the metal ions/ligands ratio

    Directory of Open Access Journals (Sweden)

    Visa Aurelia

    2012-08-01

    Full Text Available Abstract Background Research interest in phosphonates metal organic frameworks (MOF has increased extremely in the last two decades, because of theirs fascinating and complex topology and structural flexibility. In this paper we present a mathematical model for ligand/metal ion ratio of an octahedral (Oh network of cobalt vinylphosphonate (Co(vP·H2O. Results A recurrent relationship of the ratio between the number of ligands and the number of metal ions in a lamellar octahedral (Oh network Co(vP·H2O, has been deducted by building the 3D network step by step using HyperChem 7.52 package. The mathematical relationship has been validated using X ray analysis, experimental thermogravimetric and elemental analysis data. Conclusions Based on deducted recurrence relationship, we can conclude prior to perform X ray analysis, that in the case of a thermogravimetric analysis pointing a ratio between the number of metal ions and ligands number around 1, the 3D network will have a central metal ion that corresponds to a single ligand. This relation is valid for every type of supramolecular network with divalent metal central ion Oh coordinated and bring valuable information with low effort and cost.

  8. Fishnet model for failure probability tail of nacre-like imbricated lamellar materials

    Science.gov (United States)

    Luo, Wen; Bažant, Zdeněk P.

    2017-12-01

    Nacre, the iridescent material of the shells of pearl oysters and abalone, consists mostly of aragonite (a form of CaCO3), a brittle constituent of relatively low strength (≈10 MPa). Yet it has astonishing mean tensile strength (≈150 MPa) and fracture energy (≈350 to 1,240 J/m2). The reasons have recently become well understood: (i) the nanoscale thickness (≈300 nm) of nacre's building blocks, the aragonite lamellae (or platelets), and (ii) the imbricated, or staggered, arrangement of these lamellea, bound by biopolymer layers only ≈25 nm thick, occupying tail, must be determined. This objective, not pursued previously, is hardly achievable by experiments alone, since >10^8 tests of specimens would be needed. Here we outline a statistical model of strength that resembles a fishnet pulled diagonally, captures the tail of pdf of strength and, importantly, allows analytical safety assessments of nacreous materials. The analysis shows that, in terms of safety, the imbricated lamellar structure provides a major additional advantage—˜10% strength increase at tail failure probability 10^‑6 and a 1 to 2 orders of magnitude tail probability decrease at fixed stress. Another advantage is that a high scatter of microstructure properties diminishes the strength difference between the mean and the probability tail, compared with the weakest link model. These advantages of nacre-like materials are here justified analytically and supported by millions of Monte Carlo simulations.

  9. Outcomes from a modified microkeratome-assisted lamellar keratoplasty for keratoconus.

    Science.gov (United States)

    Busin, Massimo; Scorcia, Vincenzo; Zambianchi, Luca; Ponzin, Diego

    2012-06-01

    To improve visual and refractive outcomes, microkeratome-assisted lamellar keratoplasty for the treatment of keratoconus (exchange of a 9.0-mm anterior recipient lamella with a 9.0-mm donor lamella, using a 200-μm head for the former and a 300-μm head for the latter) was modified by adding a 6.5-mm incomplete full-thickness incision in the recipient bed before suturing the donor graft in place. After complete suture removal, 1 year postoperatively, best spectacle-corrected visual acuity was 20/40 or better in 92 of 97 eyes and 20/25 or better in 67 of 97 eyes; regular astigmatism was 4.5 diopters or worse in 86 of 97 eyes; endothelial cell loss averaged 20.4%. The disruption of the recipient's architecture induced by the full-thickness circular incision makes the final corneal shape closely resemble the physiologic curvature of the donor cornea, thus optimizing postoperative refractive error and spectacle-corrected visual acuity.

  10. Deep lamellar endothelial keratoplasty (DLEK): pursuing the ideal goals of endothelial replacement.

    Science.gov (United States)

    Terry, M A

    2003-11-01

    Endothelial dysfunction is a leading cause of corneal vision loss and treatment requires surgical replacement with donor endothelium. Standard penetrating keratoplasty (PK) suffers from the inherent problems of surface corneal incisions and sutures and poor wound healing of vertical stromal wounds. This often results in high irregular astigmatism, unpredictable corneal power, and the risk of long-term visual loss from suture-induced vascularization, ulceration, rejection, and late wound rupture. This paper delineates five ideal goals of endothelial replacement, which include: (1) a smooth surface topography without significant change in astigmatism from preoperative to postoperative; (2) a highly predictable and stable corneal power; (3) a healthy donor endothelium that resolves all oedema; (4) a tectonically stable globe, safe from injury and infection; and (5) an optically pure cornea. Deep lamellar endothelial keratoplasty (DLEK) is a surgical method of endothelial replacement that is performed through a limbal scleral incision that leaves the surface of the recipient cornea untouched. The early results of this innovative surgery are discussed and compared to the results of PK in terms of fulfillment of the five ideal goals of endothelial replacement. With further refinement of interface creation, DLEK surgery may be the ideal method for endothelial replacement.

  11. Deep lamellar endothelial keratoplasty in the first United States patients: early clinical results.

    Science.gov (United States)

    Terry, M A; Ousley, P J

    2001-04-01

    To report the early clinical results of the first U.S. patients to undergo deep lamellar endothelial keratoplasty (DLEK) surgery for the treatment of endothelial dysfunction. Two patients with pseudophakia with Fuchs' endothelial dystrophy, under an Institutional Review Board-approved protocol, underwent replacement of the endothelium through a limbal, scleral pocket incision (DLEK). Their vision, pachymetry, and corneal map topography were measured in the early postoperative period and were compared with preoperative measurements. Both patients had improvement in all parameters within 1 month after surgery, and corneal topography showed no significant change from before the surgery. The first patient's vision at 6 months was 20/40 (+2) with a 0.75-diopter (D) decrease in astigmatism and a normal pachymetry of 573 microm. The second patient's vision at 6 months was 20/40 (-2) with a 0.25-D increase in astigmatism and a pachymetry of 618 microm. Graft endothelial cell counts at 6 months were 1,692 and 2,631 cells/mm2, respectively. The DLEK procedure, with its absence of corneal surface incisions and sutures, preserves the preoperative topography and demonstrates good donor endothelial cell count and function early in the postoperative period. If interface clarity can be maintained, the potential advantages over penetrating keratoplasty in the treatment of endothelial dysfunction are considerable.

  12. A novel method in preparation of acellularporcine corneal stroma tissue for lamellar keratoplasty

    Science.gov (United States)

    Shao, Yi; Tang, Jing; Zhou, Yueping; Qu, Yangluowa; He, Hui; Liu, Qiuping; Tan, Gang; Li, Wei; Liu, Zuguo

    2015-01-01

    Our objective was to develop a novel lamellar cornealbiomaterial for corneal reconstruction.Theporcine acellular corneal stroma discs (ACSDs) were prepared from de-epithelized fresh porcine corneas (DFPCs) by incubation with 100% fresh human serum and additional electrophoresis at 4°C. Such manipulation removed theanterior corneal stromal cells without residual of DNA content and α-Galantigen. Human serum decellularizing activity on porcineanterior corneal stroma cells is through apoptosis, and associated with the presence of α-Gal epitopes in anterior stroma. ACSDs displayed similar optical, biomechanical properties and ultrastructure to DFPCs, and showed good histocompatibility in rabbit corneal stromal pockets and anterior chamber. Rabbit corneallamellar keratoplasty (LKP) using ACSDs showed no rejection and high transparency of cornea at 2 months after surgery. In vivo confocal laser scanning microscopy and immunostaining analysis showed complete re-epithelization and stromal cell in growth of ACSDs without inflammatory cell infiltration, new blood vessel ingrowth and excessive wound healing. In conclusion, this novel decellularization method may be valuable for preparation of xenogenic corneal tissue for clinical application, ACSDs resulted from this method may be served as a matrix equivalent for LKP in corneal xenotransplantation. PMID:26885261

  13. GaS multi-walled nanotubes from the lamellar precursor

    Science.gov (United States)

    Hu, P. A.; Liu, Y. Q.; Fu, L.; Cao, L. C.; Zhu, D. B.

    2005-04-01

    Inorganic fullerene-like (IF) nanotubes constructed from layered metal chalcogenides are of particular significance because of their excellent physical properties and potential application in wide fields. But very few previous studies were focused on the IF nanotubes of layered III-VI semiconductor. Therefore we investigate the preparation, structure and photoluminescence (PL) properties of GaS nanotube (an important III-VI semiconductor IF nanotube). A simple method is introduced to prepare GaS multi-walled nanotubes for the first time by annealing the natural lamellar precursor in Ar. The reaction temperature is crucial for the formation of nanotube. A suitable temperature range is 500-850 °C. Bulk quantities of GaS nanotubes with diameters of 30-150 nm and lengths up to ten micrometers were produced. Some of these nanotubes show corrugated and interlinked structure and form many segments, demonstrating a bamboo-like structure. As compared to bulk materials, the obvious distinction of the products in PL spectra at liquid nitrogen temperature of 77 K was due to the structure variety.

  14. Microfibril orientation dominates the microelastic properties of human bone tissue at the lamellar length scale.

    Directory of Open Access Journals (Sweden)

    Mathilde Granke

    Full Text Available The elastic properties of bone tissue determine the biomechanical behavior of bone at the organ level. It is now widely accepted that the nanoscale structure of bone plays an important role to determine the elastic properties at the tissue level. Hence, in addition to the mineral density, the structure and organization of the mineral nanoparticles and of the collagen microfibrils appear as potential key factors governing the elasticity. Many studies exist on the role of the organization of collagen microfibril and mineral nanocrystals in strongly remodeled bone. However, there is no direct experimental proof to support the theoretical calculations. Here, we provide such evidence through a novel approach combining several high resolution imaging techniques: scanning acoustic microscopy, quantitative scanning small-Angle X-ray scattering imaging and synchrotron radiation computed microtomography. We find that the periodic modulations of elasticity across osteonal bone are essentially determined by the orientation of the mineral nanoparticles and to a lesser extent only by the particle size and density. Based on the strong correlation between the orientation of the mineral nanoparticles and the collagen molecules, we conclude that the microfibril orientation is the main determinant of the observed undulations of microelastic properties in regions of constant mineralization in osteonal lamellar bone. This multimodal approach could be applied to a much broader range of fibrous biological materials for the purpose of biomimetic technologies.

  15. Microfibril orientation dominates the microelastic properties of human bone tissue at the lamellar length scale.

    Science.gov (United States)

    Granke, Mathilde; Gourrier, Aurélien; Rupin, Fabienne; Raum, Kay; Peyrin, Françoise; Burghammer, Manfred; Saïed, Amena; Laugier, Pascal

    2013-01-01

    The elastic properties of bone tissue determine the biomechanical behavior of bone at the organ level. It is now widely accepted that the nanoscale structure of bone plays an important role to determine the elastic properties at the tissue level. Hence, in addition to the mineral density, the structure and organization of the mineral nanoparticles and of the collagen microfibrils appear as potential key factors governing the elasticity. Many studies exist on the role of the organization of collagen microfibril and mineral nanocrystals in strongly remodeled bone. However, there is no direct experimental proof to support the theoretical calculations. Here, we provide such evidence through a novel approach combining several high resolution imaging techniques: scanning acoustic microscopy, quantitative scanning small-Angle X-ray scattering imaging and synchrotron radiation computed microtomography. We find that the periodic modulations of elasticity across osteonal bone are essentially determined by the orientation of the mineral nanoparticles and to a lesser extent only by the particle size and density. Based on the strong correlation between the orientation of the mineral nanoparticles and the collagen molecules, we conclude that the microfibril orientation is the main determinant of the observed undulations of microelastic properties in regions of constant mineralization in osteonal lamellar bone. This multimodal approach could be applied to a much broader range of fibrous biological materials for the purpose of biomimetic technologies.

  16. Analysis and prediction of stacking sequences in intercalated lamellar vanadium phosphates

    Energy Technology Data Exchange (ETDEWEB)

    Gautier, Romain [Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS - Ecole Nationale Superieure de Chimie de Rennes (France); Centre Nationale de la Recherche Scientifique (CNRS), Institut des Materiaux Jean Rouxel (IMN), Universite de Nantes (France); Fourre, Yoann; Furet, Eric; Gautier, Regis; Le Fur, Eric [Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS - Ecole Nationale Superieure de Chimie de Rennes (France)

    2015-04-15

    An approach is presented that enables the analysis and prediction of stacking sequences in intercalated lamellar vanadium phosphates. A comparison of previously reported vanadium phosphates reveals two modes of intercalation: (i) 3d transition metal ions intercalated between VOPO{sub 4} layers and (ii) alkali/alkaline earth metal ions between VOPO{sub 4}.H{sub 2}O layers. Both intercalations were investigated using DFT calculations in order to understand the relative shifts of the vanadium phosphate layers. These calculations in addition to an analysis of the stacking sequences in previously reported materials enable the prediction of the crystal structures of M{sub x}(VOPO{sub 4}).yH{sub 2}O (M = Cs{sup +}, Cd{sup 2+} and Sn{sup 2+}). Experimental realization and structural determination of Cd(VOPO{sub 4}){sub 2}.4H{sub 2}O by single-crystal X-ray diffraction confirmed the predicted stacking sequences. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Amniotic membrane transplantation in corneal melting after anterior lamellar keratoplasty assisted by femtosecond laser in children.

    Science.gov (United States)

    Buzzonetti, Luca; Petrocelli, Gianni; Valente, Paola

    2012-01-01

    To evaluate the efficacy of amniotic membrane transplantation in lamella melting after anterior lamellar keratoplasty (ALK) assisted by femtosecond laser in a pediatric patient. An 11-year-old girl with progressive keratoconus underwent ALK assisted by femtosecond laser on the right eye. The surgical procedure was performed under general anesthesia. The 60-KHz IntraLase femtosecond laser (Abbott Medical Optics) created both the donor (thickness 350 µm; diameter 8.1 mm; side cut 70°) and recipient (thickness 260 µm; diameter 8.0 mm; side cut 70°) lamellae. The recipient lamella was then gently removed and donor was fitted into place and sutured using 4 interrupted sutures added to a running suture in nylon 10-0. The surgery was uneventful. Two months after surgery, a lamella melting was observed. One month after topical steroid treatment, amniotic membrane transplantation was performed. When lamella melting was observed, the best-corrected visual acuity (BCVA) was 0.1 and 0.5 with foramen and no inflammatory reaction in the anterior chamber was reported. Eleven months after amniotic membrane transplantation, BCVA was 0.9 and no visual acuity increase was recorded with foramen. Our findings show that amniotic membrane transplantation could be considered in lamella melting after ALK assisted by femtosecond laser in children.

  18. Standardized big-bubble technique in deep anterior lamellar keratoplasty assisted by the femtosecond laser.

    Science.gov (United States)

    Buzzonetti, Luca; Laborante, Antonio; Petrocelli, Gianni

    2010-10-01

    We describe a variant of the big-bubble technique in deep anterior lamellar keratoplasty (DALK) assisted by the IntraLase femtosecond laser, which we call IntraBubble. The use of the 60 kHz IntraLase femtosecond laser allows dissection of the pre-Descemet-plane lamella to a predefined corneal depth and creation of a channel in the posterior stroma 50 μm above the endothelium into which a smooth cannula for air injection can be introduced. We lengthened the channel created by the laser using a pointed dissector. Eleven consecutive patients with keratoconus were treated, and all procedures were completed as DALK. The big bubble was achieved in 8 eyes (73%). In 3 cases (27%), intraoperative microperforations occurred and the procedures were completed with hand dissection without complications. This new application of femtosecond laser technology could lead to standardization of the big-bubble technique in DALK. Copyright © 2010 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  19. Clinical study of the clusters of diffuse lamellar keratitis after laser corneal refractive surgery

    Directory of Open Access Journals (Sweden)

    Qing-Hong Lin

    2017-06-01

    Full Text Available AIM: To investigate the potential causes and management of the clusters of diffuse lamellar keratitis(DLKafter laser corneal refractive surgery. METHODS: The study enrolled 98 eyes(53 patientscomplicated with DLK after receiving laser in situ keratomileusis(LASIK, FS-LASIK or small-incision lenticule extraction(SMILEin our center from February 10th,2016 to February 22th,2016. They were given clinical classification treatments according to corneal layer inflammatory extent and then followed up after 1, 3, 5, 7, 10d and 1mo. RESULTS: The clusters of DLK occurred 5 times in the study period. The incidence and degree of DLK significantly decreased after changed the sterilization, surgical equipments, temperature and humidity of the operating room. There were 80 eyes(82%had stage 1 DLK, 11 eyes(11%had stage 2, 4 eyes(4%had stage 3 and 3 eyes(3%had stage 4. The incidence of DLK after FS-LASIK was 40%(79 eyes in 42 patients, that after LASIK assistant by Hastome keratome was 45%(10 eyes in 5 patients, that after SMILE was 20%(9 eyes in 6 patients. After intensive treatment, as glucocorticoid treatment and flap lifting flushing, all cases recovered within 1mo. CONCLUSION: The outbreak of DLK may be associated with the disposable item, flushing liquor, temperature and humidity of the operating room. Early diagnosis, prevention and treatment are the key of decreasing the incidence of DLK.

  20. Nacre-mimetic bulk lamellar composites reinforced with high aspect ratio glass flakes.

    Science.gov (United States)

    Guner, Selen N Gurbuz; Dericioglu, Arcan F

    2016-12-05

    Nacre-mimetic epoxy matrix composites reinforced with readily available micron-sized high aspect ratio C-glass flakes were fabricated by a relatively simple, single-step, scalable, time, cost and man-power effective processing strategy: hot-press assisted slip casting (HASC). HASC enables the fabrication of preferentially oriented two-dimensional inorganic reinforcement-polymer matrix bulk lamellar composites with a micro-scale structure resembling the brick-and-mortar architecture of nacre. By applying the micro-scale design guideline found in nacre and optimizing the relative volume fractions of the reinforcement and the matrix as well as by anchoring the brick-and-mortar architecture, and tailoring the interface between reinforcements and the matrix via silane coupling agents, strong, stiff and tough bio-inspired nacre-mimetic bulk composites were fabricated. As a result of high shear stress transfer lengths and effective stress transfer at the interface achieved through surface functionalization of the reinforcements, fabricated bulk composites exhibited enhanced mechanical performance as compared to neat epoxy. Furthermore, governed flake pull-out mode along with a highly torturous crack path, which resulted from extensive deflection and meandering of the advancing crack around well-aligned high aspect ratio C-glass flakes, have led to high work-of-fracture values similar to nacre.

  1. Imaging of intracellular spherical lamellar structures and tissue gross morphology by a focused ion beam/scanning electron microscope (FIB/SEM)

    Energy Technology Data Exchange (ETDEWEB)

    Drobne, Damjana [Department of Biology, University of Ljubljana, Vecna pot 111, SI-1000 Ljubljana (Slovenia)], E-mail: damjana.drobne@bf.uni-lj.si; Milani, Marziale [Materials Science Department, University of Milano-Bicocca, Via Cozzi 53, I-20125 Milano (Italy); Leser, Vladka [Department of Biology, University of Ljubljana, Vecna pot 111, SI-1000 Ljubljana (Slovenia); Tatti, Francesco [FEI Italia, Via Cervi 40, I-00139 Roma (Italy); Zrimec, Alexis [Institute of Physical Biology, Velika Loka 90, SI-1290 Grosuplje (Slovenia); Znidarsic, Nada; Kostanjsek, Rok; Strus, Jasna [Department of Biology, University of Ljubljana, Vecna pot 111, SI-1000 Ljubljana (Slovenia)

    2008-06-15

    We report the use of a focused ion beam/scanning electron microscope (FIB/SEM) for simultaneous investigation of digestive gland epithelium gross morphology and ultrastructure of multilamellar intracellular structures. Digestive glands of a terrestrial isopod (Porcellio scaber, Isopoda, Crustacea) were examined by FIB/SEM and by transmission electron microscopy (TEM). The results obtained by FIB/SEM and by TEM are comparable and complementary. The FIB/SEM shows the same ultrastructural complexity of multilamellar intracellular structures as indicated by TEM. The term lamellar bodies was used for the multillamellar structures in the digestive glands of P. scaber due to their structural similarity to the lamellar bodies found in vertebrate lungs. Lamellar bodies in digestive glands of different animals vary in their abundance, and number as well as the thickness of concentric lamellae per lamellar body. FIB/SEM revealed a connection between digestive gland gross morphological features and the structure of lamellar bodies. Serial slicing and imaging of cells enables easy identification of the contact between a lamellar body and a lipid droplet. There are frequent reports of multilamellar intracellular structures in different vertebrate as well as invertebrate cells, but laminated cellular structures are still poorly known. The FIB/SEM can significantly contribute to the structural knowledge and is always recommended when a link between gross morphology and ultrastrucutre is investigated, especially when cells or cellular inclusions have a dynamic nature due to normal, stressed or pathological conditions.

  2. Conformational dynamics of dry lamellar crystals of sugar based lipids: an atomistic simulation study.

    Directory of Open Access Journals (Sweden)

    Vijayan ManickamAchari

    Full Text Available The rational design of a glycolipid application (e.g. drug delivery with a tailored property depends on the detailed understanding of its structure and dynamics. Because of the complexity of sugar stereochemistry, we have undertaken a simulation study on the conformational dynamics of a set of synthetic glycosides with different sugar groups and chain design, namely dodecyl β-maltoside, dodecyl β-cellobioside, dodecyl β-isomaltoside and a C12C10 branched β-maltoside under anhydrous conditions. We examined the chain structure in detail, including the chain packing, gauche/trans conformations and chain tilting. In addition, we also investigated the rotational dynamics of the headgroup and alkyl chains. Monoalkylated glycosides possess a small amount of gauche conformers (∼20% in the hydrophobic region of the lamellar crystal (LC phase. In contrast, the branched chain glycolipid in the fluid Lα phase has a high gauche population of up to ∼40%. Rotational diffusion analysis reveals that the carbons closest to the headgroup have the highest correlation times. Furthermore, its value depends on sugar type, where the rotational dynamics of an isomaltose was found to be 11-15% and more restrained near the sugar, possibly due to the chain disorder and partial inter-digitation compared to the other monoalkylated lipids. Intriguingly, the present simulation demonstrates the chain from the branched glycolipid bilayer has the ability to enter into the hydrophilic region. This interesting feature of the anhydrous glycolipid bilayer simulation appears to arise from a combination of lipid crowding and the amphoteric nature of the sugar headgroups.

  3. Comparison of different methods of glycerol preservation for deep anterior lamellar keratoplasty eligible corneas.

    Science.gov (United States)

    Li, Jinyang; Shi, Shuai; Zhang, Xin; Ni, Shouxiang; Wang, Yu; Curcio, Christine A; Chen, Wei

    2012-08-17

    To compare different methods of glycerol-preserved corneas intended for deep anterior lamellar keratoplasty (DALK). We analyzed transparency, transmittance, thickness, biomechanics, morphology, and antigenicity of donor corneas preserved by four different glycerol-based methods (n = 6 per group) for 3 months, as follows: tissues in anhydrous glycerol without aluminosilicate molecular sieves at room temperature (GRT); tissues in anhydrous glycerol with aluminosilicate molecular sieves at room temperature (SRT); tissues in anhydrous glycerol without aluminosilicate molecular sieves at -78°C (G78); and tissues in anhydrous glycerol without aluminosilicate molecular sieves at -20°C (G20). Slit lamp images and transmittance curves obtained by spectrophotometer show that the G78 cornea was the most transparent tissue. Stress-strain behavior indicated that corneas in the G78 group were the most pliable, and SRT corneas were the stiffest. Electron microscopy analysis indicated that corneal cytoarchitecture and keratocyte integrity was destroyed in all glycerol-preserved corneas. Disorganized stromal collagen fibers were evident in groups stored at RT. Especially in SRT corneas, parallelism was lost, fibrils were extremely tortuous and discontinuous, and widespread fibril degeneration could be found. Antigenicity of tissue, assessed via immunohistochemistry for CD45-positive cells, HLA-ABC and HLA-DR, was lowered after glycerol preservation relative to fresh cornea tissues, and immunoreactivity was located mainly on corneal epithelium and limbus rather than stroma. Anhydrous glycerol preservation without molecular sieves in a -78°C freezer was the best method to obtain DALK-eligible tissues that were both transparent and pliable.

  4. Changes in corneal endothelial cell profile measurements after deep anterior lamellar keratoplasty for keratoconus.

    Science.gov (United States)

    Salouti, Ramin; Masoumpour, Masoumeh; Nowroozzadeh, Mohammad H; Zamani, Mohammad; Ghoreyshi, Maryam; Melles, Gerrit R J

    2013-06-01

    The primary objective was to evaluate whether postoperative alterations in corneal shape (as reflected by keratometry values) affect endothelial cell profile measurements after deep anterior lamellar keratoplasty (DALK) in a group of patients with keratoconus. Secondary objective was to describe the pattern of changes in corneal endothelial cell profile measurements during the first 3 years after DALK. In this prospective interventional case series, we enrolled patients who had significant keratoconus and were scheduled for DALK (Melles technique). Cases with concomitant intraocular surgeries, intra-/postoperative complications, and poor quality of images were excluded. Two hundred one eyes and 45 eyes (of the original 201) were enrolled for evaluating the primary and the secondary objectives, respectively. At 3 months post DALK, the mean endothelial cell density (ECD) had significantly increased and the mean cell area had decreased compared with preoperative measurements (2721 vs. 2823 cells/mm2, P = 0.015; and 378 vs. 362 μm2, P = 0.005, respectively). Regression analysis revealed a weak but significant nonlinear association between changes in mean keratometry and ECD changes at 3 months (R2 = 0.039, P = 0.02). Standard deviation of mean cell area had significantly decreased at 12 months after DALK compared with measurements taken at 3 months after surgery (P = 0.023) and remained stable thereafter. Apparent measurements of ECD may not show a decrease but instead even a slight increase in some cases after uncomplicated DALK (Melles technique) for keratoconus. This finding along with a later decrease in standard deviation of mean cell area suggests that notable postoperative changes in corneal biomechanical forces may affect endothelial cell profile measurements.

  5. Gelling Lamellar Phases of the Binary System Water-Didodecyldimethylammonium Bromide with an Organogelator.

    Science.gov (United States)

    Koitani, Sachi; Dieterich, Sonja; Preisig, Natalie; Aramaki, Kenji; Stubenrauch, Cosima

    2017-10-31

    Does the presence of a gel network influence the properties of a lyotropic liquid crystal? Does the replacement of oil by a lyotropic liquid crystal influence the properties of an organogel? To answer these questions we study gelled lyotropic liquid crystals (LLC). In the present study we show that it is possible to gel the lamellar phase of the binary system water-didodecyl dimethylammonium bromide (2C12DAB) with the organogelator 12-hydroxyoctadecanoic acid (12-HOA). We compare various properties of the gelled LLC phases with the "parent systems", i.e., with the binary organogel consisting of n-decane-12-HOA and with the nongelled LC phases, respectively. Optical and electron microscopy, differential scanning calorimetry (DSC), rheometry, as well as small and wide-angle X-ray scattering (SWAXS) proved the coexistence of an Lα phase and a 12-HOA gel network in the gelled Lα phase. However, a small influence of the Lα phase on the gel properties was seen, namely slightly lower sol-gel transition temperatures and viscoelastic moduli of the gelled Lα phase compared to the binary gel. On the other hand, the presence of the gel also has an influence on the Lα phase: the interlayer spacing of the surfactant bilayers in the gelled Lα phases is slightly larger compared to the nongelled Lα phases, which is due to mixing part of the 12-HOA molecules in the Lα bilayers. Despite this mutual influence the structures of both the Lα phase and the gel network are hardly disturbed in the gelled Lα phase, i.e., that the self-assembly of the surfactant and of the gelator molecules clearly occur in an orthogonal way.

  6. Graft biomechanical properties after penetrating keratoplasty versus deep anterior lamellar keratoplasty.

    Science.gov (United States)

    Jafarinasab, Mohammad Reza; Feizi, Sepehr; Javadi, Mohammad Ali; Hashemloo, Ali

    2011-05-01

    To compare biomechanical properties of transplanted corneas after penetrating keratoplasty (PK) with those after deep anterior lamellar keratoplasty (DALK) using Anwar's big-bubble technique. This cross-sectional comparative study consisted of 45 PK eyes (group 1) and 23 DALK eyes (group 2) with the underlying pathology of keratoconus. The Ocular Response Analyzer was used to measure Goldmann-correlated intraocular pressure (IOPg) and cornea-compensated IOP (IOPcc), as well as graft biomechanical properties, namely corneal hysteresis (CH) and corneal resistance factor (CRF). The results were compared between the study groups using independent t-test. Mean patient age was 29.8 ± 6.1 years in group 1 and 27.2 ± 6.5 years in group 2 (P = 0.11) and they were followed up for 31.4 ± 19.0 months and 29.2 ± 17.3 months after corneal transplantation, respectively (P = 0.27). There was no significant difference between the study groups in terms of recipient (P = 0.21) and donor (P = 0.57) trephine sizes or BSCVA (P = 0.77). CH was measured 10.09 ± 2.5 mmHg in group 1 and 9.64 ± 2.1 mmHg in group 2 (P = 0.36). CRF was 10.13 ± 2.2 and 9.36 ± 2.1 mmHg, respectively (P = 0.17). Similarly, no significant difference was found between group 1 and group 2 in terms of IOPg (P = 0.25) and IOPcc (P = 0.80). DALK using the big-bubble technique for keratoconic eyes provides corneal biomechanics comparable to PK.

  7. Office-based Relaxing Incision Procedure for Correction of Astigmatism after Deep Anterior Lamellar Keratoplasty

    Science.gov (United States)

    Javadi, Mohammad Ali; Feizi, Sepehr; Mirbabaee, Firooz; Fekri, Yousef

    2017-01-01

    Purpose: To report the outcomes of a simple and effective office-based procedure for the correction of astigmatism after deep anterior lamellar keratoplasty (DALK). Methods: This study enrolled 24 consecutive keratoconic eyes that developed an intolerable amount of graft astigmatism after DALK. The location and extension of steep semi-meridians were determined using corneal topography. Office-based relaxing incision procedures were performed at the slit-lamp biomicroscope using a 27-gauge needle. Relaxing incisions were made at the donor-recipient interface on one side of the steepest meridian with an arc length of 45° to 60° and an initial depth of approximately 70–80% of the corneal thickness. Topography was performed after 30–40 minutes and the initial incision was enhanced in depth and length. If an acceptable amount of astigmatism was not achieved, another incision was created at the opposite semi-meridian during the same session. Results: Mean follow-up period was 13.1 ± 7.4 months. Mean preoperative best spectacle corrected visual acuity was 0.26 ± 0.14 logMAR, increasing to 0.22 ± 0.09 logMAR after the procedure (P = 0.20). Mean spherical equivalent refractive error increased from − 4.64 ± 3.06 diopters (D) preoperatively to −6.06 ± 3.15 D postoperatively (P = 0.01). Mean keratometric astigmatism was reduced by 2.95 ± 3.43 D and 5.16 ± 2.97 D measured using subtraction and vector analysis methods, respectively (P astigmatism after DALK. This approach effectively decreases the need for the more costly alternative in the operating room. PMID:28540006

  8. Relaxing incisions combined with adjustment sutures for post-deep anterior lamellar keratoplasty astigmatism in keratoconus.

    Science.gov (United States)

    Javadi, Mohammad Ali; Feizi, Sepehr; Mirbabaee, Firooz; Rastegarpour, Ali

    2009-12-01

    To find an effective and reliable method to correct astigmatism after deep anterior lamellar keratoplasty (DALK) in patients with keratoconus. This interventional case series included 14 eyes of 14 patients with keratoconus (12 males) undergoing graft refractive surgery (GRS) for intolerable post-DALK astigmatism. The technique of GRS for the 5 initial cases consisted of only relaxing incisions at the steep meridian in the graft-host interface down to Descemet membrane. For the rest, the relaxing incisions at the steep meridian were accompanied by simultaneous suturing and the effect of the relaxing incisions was controlled through selective suture removal starting a few days after the operation. The main outcomes were uncorrected and corrected visual acuity and change in refractive and keratometric astigmatism using subtraction and vector analysis methods. Mean patient age was 29.36 +/- 6.2 years. Mean time interval from complete suture removal to GRS and follow-up period were 4.5 +/- 2.0 months and 12.0 +/- 7.4 months, respectively. Mean preoperative best-corrected visual acuity was 0.29 +/- 0.1, increasing to 0.22 +/- 0.1 logarithm of minimum angle of resolution after the operation (P = 0.007). Average keratometric astigmatism was reduced by 3.8 and 5.5 diopters measured with subtraction and vector analysis methods, respectively. Four of 5 eyes that had only relaxing incisions initially required suturing of the incisions because of overcorrection, whereas preliminary results showed none of the 9 patients undergoing simultaneous relaxing incisions and suturing required further intervention. Relaxing incisions and suturing at the steep meridian followed by selective suture removal can effectively and predictably reduce post-DALK astigmatism in patients with keratoconus.

  9. Deep anterior lamellar keratoplasty using big-bubble technique for treatment of corneal stromal scars.

    Science.gov (United States)

    Arslan, Osman Sevki; Ünal, Mustafa; Tuncer, Ibrahim; Yücel, Iclal

    2011-06-01

    To report the clinical outcomes of deep anterior lamellar keratoplasty (DALK) in patients with anterior corneal stromal scars associated with various etiologies. A total of 79 eyes of 79 patients with corneal stromal scars sparing the Descemet membrane and the endothelium underwent DALK by using big-bubble technique. The main outcome measures of the study were the ability to successfully complete DALK, intraoperative and postoperative complications, best spectacle-corrected visual acuity, refraction, and graft clarity. Seventy-two of the surgical procedures were carried out as DALK, and the mean follow-up time was 28.1 ± 17.9 months (range, 12-78 months). The most frequent indication for DALK surgery was postherpetic keratitis (44%). Complete Descemet membrane exposure via big bubble (descemetic DALK) could be achieved in 57 cases (79%). Fifteen eyes (21%) required layer-by-layer manual dissection (predescemetic DALK). Best spectacle-corrected visual acuity of 6/12 or better was present in 59 eyes (82%) postoperatively. The mean spherical equivalent and topographic astigmatism were -3.32 ± 2.13 (range, -9.13 to +4.75) and -2.97 ± 1.94 (range, -8.0 to +4.50) diopter, respectively. There were 2 instances of stromal graft rejection, which responded to medical therapy. DALK big-bubble technique may be a valuable and safe treatment in patients with corneal stromal scar with healthy endothelium. The visual and refractive outcomes are comparable to standard penetrating keratoplasty, avoiding the risk of endothelial rejection.

  10. Femtosecond laser-assisted lamellar keratoplasty (FSLK) for anterior corneal stromal diseases.

    Science.gov (United States)

    Almousa, Radwan; Samaras, Konstantinos E; Khan, Saj; Lake, Damian B; Daya, Sheraz M

    2014-02-01

    Our objective was to study the outcome of femtosecond-assisted lamellar keratoplasty (FSLK) in stromal corneal diseases. This is a retrospective chart review of 17 patients (20 eyes) who underwent FSLK for anterior corneal pathologies. Main outcome measures were refractive results following FSLK, complications, and graft survival. Mean follow-up time was 42 ± 15 (7-58) months. Preoperative best spectacle-corrected visual acuity (BSCVA) was ≤20/40 in 17 eyes. Postoperative BSCVA ≥ 20/40 was achieved in 12/14 at 12 months, 11/12 at 24 months, and 10/12 eyes at 36 months; postoperative BSCVA ≥ 20/25 was achieved in 8/14, 8/12, and 5/12 eyes at 12, 24, and 36 months, respectively. One eye had vertical gas break through the epithelium during the FSLK. One eye had postoperative epithelial rejection and two eyes had stromal rejection treated successfully with topical steroids. Another eye had epithelial ingrowth that was not progressive; however, the same eye developed bacterial keratitis and scarred graft 32 months post-FSLK. One eye had graft dehiscence and one eye developed excessive interface fibrosis. Five out of 20 grafts failed due to the recurrence of the original disease (3), corneal scarring (1), and excessive interface fibrosis (1). FSLK provides many advantages over conventional PK and DALK, with faster visual rehabilitation and emmetropization of the manifest refraction rather than inducing ametropia and irregular astigmatism.

  11. Comparison of refractive changes after deep anterior lamellar keratoplasty and penetrating keratoplasty for keratoconus.

    Science.gov (United States)

    Kim, Kuk-Hyoe; Choi, Sung-Ho; Ahn, Kyeon; Chung, Eui-Sang; Chung, Tae-Young

    2011-03-01

    To compare refractive changes occurring after deep anterior lamellar keratoplasty (DALK) or penetrating keratoplasty (PKP) in patients with keratoconus. We retrospectively reviewed the medical records of 57 patients with keratoconus who received DALK (19 eyes of 19 patients) or PKP (38 eyes of 38 patients) before and after surgery between January 1996 and January 2008, in an effort to evaluate the surgical results and clinical courses. The principal outcome measures were as follows: preoperative and postoperative uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), manifest refraction, and corneal topography including anterior chamber depth (ACD). We noted no significant difference between the DALK and PKP groups in terms of postoperative UCVA, BCVA, astigmatism, or donor-recipient graft size disparities. For the PKP and DALK groups, the mean postoperative spheres were -1.64 D and -4.29 D at 6 months (P = 0.01) and -2.73 D and -4.22 D at 12 months, respectively (P = 0.04). Postoperative mean central corneal powers (3.0/5.0 mm zone) were 45.01/45.03 D and 46.94/47.84 D, respectively (P = 0.04 and P = 0.02). ACD after surgery was 3.25 and 3.37 mm at the final follow-up, respectively (P = 0.02). Although DALK is a safe alternative in cases of keratoconus, the DALK group evidenced significantly higher myopia than did the PKP group, which was related to steeper central corneal power and deeper ACD.

  12. Comparison of femtosecond laser-assisted deep anterior lamellar keratoplasty and penetrating keratoplasty for keratoconus.

    Science.gov (United States)

    Chen, Yueqin; Hu, Dan-Ning; Xia, Yuan; Yang, Liping; Xue, Chunyan; Huang, Zhenping

    2015-10-27

    To compare outcomes of femtosecond laser-assisted deep anterior lamellar keratoplasty (FSL-DALK) and penetrating keratoplasty (FSL-PK) for the treatment of keratoconus. Twenty eight eyes underwent FSL-DALK (consisted of 12 eyes in the FSL-DALKa subgroup without baring the Descemet's membrane and 16 eyes in the FSL-DALKb subgroup baring the Descemet's membrane using big-bubble technique) were compared with 12 eyes that underwent FSL-PK for keratoconus. These patients underwent an ophthalmic examination preoperatively and 3, 6, 9, and 12 months postoperatively. The postoperative BCVA in the FSL-PK group, and the FSL-DALKb subgroup were significantly better than that in the FSL-DALKa subgroup (P  0.05). There were no significant differences in the mean spherical equivalent (SE) and astigmatism between the FSL-DALK and the FSL-PK groups, nor between the subgroups of FSL-DALK during the follow-up period (P > 0.05). At the last follow-up, the mean endothelial cell loss in the FSL-DALK group (9.12 %) was significantly less than that in the FSL-PK group (20.79 %) (P < 0.001), while there was no difference between the FSL-DALKa (9.15 %) and the FSL-DALKb (9.10 %) subgroups (P = 0.15). The FSL-DALK group seemed to have fewer graft rejections (1/28 cases) than the FSL-PK group (2/12 cases), although Kaplan-Meier curve showed no significant difference between the two groups (P = 0.144). In this retrospective study, the results suggested that FSL-DALKb gives better visual outcome, and FSL-DALKb is a better option for keratoconus whose endothelium is not compromised. However, larger and prospective studies are further required.

  13. Comparison of astigmatic keratotomy results in deep anterior lamellar keratoplasty and penetrating keratoplasty in keratoconus.

    Science.gov (United States)

    Kubaloglu, Anil; Coskun, Erol; Sari, Esin Sogutlu; Guneş, Alime Sefer; Cinar, Yasin; Piñero, David P; Kutluturk, Isil; Ozerturk, Yusuf

    2011-04-01

    To compare astigmatic keratotomy (AK) outcomes in high astigmatism after deep anterior lamellar keratoplasty (DALK) and after penetrating keratoplasty (PK) in keratoconus patients. Prospective, comparative, interventional case series. This study comprised 20 eyes that underwent DALK and 24 eyes that underwent PK. After suture removal, all eyes had more than 5 diopters (D) of astigmatism and underwent standard manual 1-pair, 90-degree, and 90% corneal thickness AK incisions. The main outcome measures included preoperative and postoperative manifest refraction, uncorrected visual acuity, best spectacle-corrected visual acuity, surgically induced astigmatism, Orbscan II (Bausch & Lomb) corneal topography results, keratometric astigmatism, and complications. All eyes completed 6 months of follow-up. The overcorrection rate was 35% and 41.6% in the DALK and PK groups, respectively (P=.75). At 6 months after AK, logarithm of the minimal angle of resolution uncorrected visual acuity improved from 0.88 ± 0.20 to 0.54 ± 0.26 and from 1.0 ± 0.34 to 0.53 ± 0.26 in the DALK and PK groups, respectively (P=.01 to Pastigmatism was 6.10 ± 3.27 D in the DALK group and 7.15 ± 2.98 D in the PK group (P=.36). The manual AK for the treatment of postkeratoplasty astigmatism after DALK and PK in keratoconus patients is a safe and effective surgical procedure, allowing similar refractive cylinder reduction and improvement in uncorrected visual acuity and best spectacle-corrected visual acuity. Copyright © 2011 Elsevier Inc. All rights reserved.

  14. Laser in situ keratomileusis to manage refractive errors after deep anterior lamellar keratoplasty.

    Science.gov (United States)

    Acar, Banu Torun; Utine, Canan A; Acar, Suphi; Ciftci, Ferda

    2012-06-01

    To analyze the visual and refractive outcomes of laser in situ keratomileusis (LASIK) after deep anterior lamellar keratoplasty (DALK) for keratoconus. Haydarpasa Numune Education and Research Hospital, Ophthalmology Clinic, Istanbul, Turkey. Cohort study. Patients with compound myopic astigmatism after DALK and a spherical equivalent (SE) between -2.50 diopters (D) and -8.00 D had LASIK as a single-step procedure, correcting the manifest refraction error. The visual and refractive results at 1 month, 3 months, and the last follow-up were compared with preoperative values. The mean follow-up was 11.17 months ± 3.61 (SD). The mean manifest refraction SE (MRSE) and autorefractometer measurements and the autokeratorefractometer and corneal topography keratometry readings decreased significantly from preoperatively to 1 month postoperatively (P.05). Preoperatively, the mean uncorrected (UDVA) and corrected (CDVA) distance visual acuities were 0.21 ± 0.08 and 0.73 ± 0.08, respectively; postoperatively, the means were 0.73 ± 0.10 and 0.98 ± 0.05, respectively. All eyes achieved a postoperative UDVA better than 0.5. No eye lost CDVA lines. The safety index was 1.34. The mean MRSE was -5.18 ± 1.74 D preoperatively and -1.05 ± 0.64 D postoperatively (P<.01). Postoperatively, 11 eyes (91.67%) were within ± 2.00 D of the SE, 8 (6.67%) were within ± 1.00 D, and 5 (41.67%) were within ± 0.50 D. No complications were encountered. Treatment of post-DALK keratoconus patients with LASIK to correct manifest refraction error seems to be a viable option. Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  15. [The visual functional therapeutic effects of deep lamellar keratoplasty and penetrating keratoplasty for fungal corneal ulcer].

    Science.gov (United States)

    Lu, Qin-kang; Tong, Qi-hu; Lai, Xiao-ming; Wang, Hui-yun; Zhao, Na

    2011-05-01

    To investigate the visual functional therapeutic effects of deep lamellar keratoplasty (DLK) and penetrating keratoplasty (PK) on perforated fungal keratitis. 64 patients (64 eyes) of fungal corneal ulcer in Ophthalmology Center of Ningbo Yinzhou People Hospital from 2004 to 2009 were retrospected, of which undergo DLK (36 patients, 36 eyes) and PK (28 patients, 28 eyes), and followed up by 12 to 24 months. Check two sets of patients' VA and refraction before operation, and analyze the best-corrected visual acuity (BCVA), corneal refraction changes, corneal endothelium counting and complications, using χ(2) test and t-test. The BCVA after the operation of two sets are both improved, 32 eyes of DLK set were above 0.4, 19 eyes of PK set were above 0.4, of which the DKL set is a bit better than PK set (χ(2) = 4.304, P > 0.05). The astigmatism of DLK set is smaller than the PK set after operation, and there is significant difference (χ(2) = 4.98, P astigmatism of two sets on the average were all no more than 5.00 D. The reject reaction of keratoplasty of DLK is less than PK, there is obviously significant difference (χ(2) = 34.17, P < 0.05). There is less complications of DLK than PK for fungal corneal ulcer. DLK can reduce the occurrence of reject reaction of endothelium type, and the BCVA, refraction of DLK after operation is similar to PK, the incidence rate of surgical operation failure is low.

  16. Lamellar corneal lenticule graft to treat keratolysis after AlphaCor keratoprosthesis implantation.

    Science.gov (United States)

    Hoffart, Louis; Carles, Gérard; Matonti, Frédéric

    2015-01-01

    Clinical assessment of AlphaCor keratoprosthesis and evaluation of surgical method to treat keratolysis in case of stromal necrosis occurrence. This is a noncomparative, retrospective, interventional case series. The medical records of 12 eyes of 12 patients who underwent consecutive AlphaCor keratoprosthesis implantations were reviewed. Patients with severe bilateral corneal pathology unsuitable for a conventional corneal graft, a best-corrected visual acuity (BCVA) from light perception (LP) to 20/200, with no active ocular surface inflammation, controlled intraocular pressure prior to the surgery, and an unstimulated Schirmer test of >2.5 mm at 5 minutes were included. Postoperative medications included topical dexamethasone, ciprofloxacin, and 2% cyclosporine A. Main outcome measures included BCVA and complications occurrence. After a mean follow-up of 25 ± 12.3 months (range 2-38 months), 8 (66.7%) AlphaCor devices were retained. Postoperative BCVA ranged from LP to 20/63 (mean gain of 2.5 ± 3.1 lines). Seven cases of stromal melt (58.3%) occurred. Three were reversed to penetrating keratoplasty and 3 had a donor corneal layer fixated over the AlphaCor with satisfactory results (mean follow-up 23 ± 1.6 months). There were no instances of endophthalmitis, retinal detachment, or glaucoma exacerbation. AlphaCor showed a low incidence of the classic keratoprosthesis complications but a high occurrence of recipient cornea necrosis. Corneal melts were successfully managed in 3 cases by lamellar corneal lenticule graft, thereby increasing the retention of AlphaCor and maintaining BCVA.

  17. Repeat Keratoplasty for Failed Deep Anterior Lamellar Keratoplasty in Keratoconus: Incidence, Indications, and Outcomes.

    Science.gov (United States)

    Feizi, Sepehr; Javadi, Mohammad Ali; Khajuee-Kermani, Pejman; Jafari, Roya

    2017-05-01

    To analyze the incidence, indications, and clinical outcomes of penetrating keratoplasty (PK) and repeat deep anterior lamellar keratoplasty (DALK) after failed DALK for keratoconus. This retrospective interventional case series reviewed the medical records of patients with keratoconus who underwent DALK and were followed up for at least 1 year. Patients who underwent PK or repeat DALK for failed DALK were identified. The incidence, indications, and clinical outcomes after repeat keratoplasty were assessed. A total of 382 consecutive eyes with keratoconus underwent DALK over a 9-year period. Graft failure was observed in 14 eyes (3.7%). The reasons for the graft failure included nonhealing epithelial defects (n = 1), pseudoanterior chamber (n = 2), patient dissatisfaction with vision (n = 4), interface opacification (n = 4), high astigmatism (n = 1), and recurrence of keratoconus in the graft (n = 2). Of these 14 eyes with graft failure, 12 eyes underwent PK (n = 11) or repeat DALK (n = 1). At the most recent examination, which was performed 49.7 ± 25.2 months after the secondary graft, all regrafts were clear. There was no significant difference between eyes with clear first grafts and eyes that underwent PK or repeat DALK in visual outcomes at the final examination. Graft rejection was the most common complication, which was encountered in 75% of the regrafts. The prognosis for repeat keratoplasty was excellent, and the outcomes of secondary grafts were comparable to those of primary DALK grafts. However, the rate of rejection with secondary grafts was high, necessitating close follow-up after PK and repeat DALK performed for failed DALK.

  18. Systematic review comparing penetrating keratoplasty and deep anterior lamellar keratoplasty for management of keratoconus.

    Science.gov (United States)

    Henein, Christin; Nanavaty, Mayank A

    2017-02-01

    Perception of reduced incidence of graft rejection after deep anterior lamellar keratoplasty (DALK) has attracted many surgeons towards this technique in keratoconus. This review aims to compare the visual, refractive and graft outcomes after penetrating keratoplasty (PK) and DALK for keratoconus. Electronic searches of PubMed, MEDLINE, EMBASE, Latin American and Caribbean Health Sciences Literature database (LILACS), metaRegister of Controlled Trials (mRCT), ClinicalTrial.gov and the WHO International Clinical Trials Registry Platform (ICTRP) were performed. We included randomized control trials (RCTs) and comparative studies to assess primary and secondary outcomes after PK and DALK in eyes with keratoconus. Primary outcome was best-corrected visual acuity (BCVA) LogMAR at ≥6 months. Secondary outcomes included number of patients with BCVA≥0 LogMAR, uncorrected visual acuity (UCVA) LogMAR, spherical equivalent (SE), refractive and keratometric astigmatism, endothelial cell density (ECD) cell/mm2, graft rejection and graft survival. Eighteen studies (including 2 RCTs) compared DALK (965 eyes) and PK (2402 eyes) for keratoconus. There was strong evidence through RCTs suggesting better LogMAR BCVA at ≥6 months and better LogMAR UCVA with PK; reduced refractive astigmatism and rejection with DALK and no difference in SE and keratometric astigmatism. Moreover, there was weak evidence to suggest better BCVA≥0 LogMAR after PK and no difference in ECD between the two techniques. Despite the popularity of DALK amongst corneal surgeons for keratoconus, there is a paucity of high quality RCTs. The existing limited evidence confirms reduced rejection and refractive astigmatism with DALK but better visual outcomes with PK. Internationally agreed data sets and follow-up protocol are warranted. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  19. Modified big-bubble deep anterior lamellar keratoplasty using peripheral air injection.

    Science.gov (United States)

    Feizi, Sepehr; Faramarzi, Amir; Javadi, Mohammad Ali; Jafarinasab, Mohammad Reza

    2014-11-01

    To introduce a modification to big-bubble deep anterior lamellar keratoplasty (DALK) which can decrease the risk of Descemet membrane (DM) perforation during air injection. In Anwar's big-bubble technique, a 27-guage needle is inserted from the trephination site and advanced into the corneal stroma up to the centre. The technique we introduce modifies the original technique in the following fashion. After trephination to approximately 80% of corneal thickness, a 27-guage needle is inserted into the stroma peripherally from the trephination site towards the limbus. Air is injected gently into the deep stroma until a big bubble is formed. This technique was performed in 16 consecutive keratoconic eyes undergoing DALK. Additionally, peripheral air injection was carried out in 27 eye-bank corneas using a peripheral approach. In all (100%) eye-bank and 13 (81.3%) live corneas, a successful big bubble was easily achieved following peripheral air injection. In these 13 live corneas, all bubbles were formed at the central (n=10) or paracentral (n=3) cornea and extended centrifugally (type 1 bubble). In one of these corneas, an additional three bubbles were noted in the periphery between the DM and the pre-Descemet posterior stromal layer (Dua's layer, type 2) after a type 1 bubble was formed. In two live corneas in which peripheral air injection failed, a big bubble was successfully formed after air was injected inside the trephination site. Air injection peripheral to the trephination site is a reproducible modification to the standard technique which can decrease the risk of DM perforation during air injection. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  20. Factors influencing big-bubble formation during deep anterior lamellar keratoplasty in keratoconus.

    Science.gov (United States)

    Feizi, Sepehr; Javadi, Mohammad Ali; Daryabari, Seyed-Hashem

    2016-05-01

    To investigate recipient and operative factors that can influence the rate of achieving a bare Descemet's membrane (DM) during deep anterior lamellar keratoplasty (DALK) for keratoconus. In this retrospective comparative study, a total of 290 (153 right) consecutive eyes from 257 (179 male) keratoconus-affected patients who underwent DALK with the big-bubble technique were enrolled. Univariate analyses and multiple logistic regressions were used to investigate factors including patient age and sex, family history of keratoconus, history of contact lens wear or vernal keratoconjunctivitis, the presence of Vogt's striae or superficial stromal opacities, keratometric readings, corneal diameter, central and peripheral corneal thickness, anterior chamber depth, vitreous length, and trephination size, which could predict achievement of a bare DM. The surgery was completed as a DALK in 289 of 290 eyes, and a bare DM was successfully achieved in 229 (79.2%) eyes. The recipient sex and trephination size significantly influenced the success rate of big-bubble formation. Females had decreased odds of achieving a bare DM by 0.44 times (p=0.02). For each 0.1 mm increase in the trephination size, the odds of a successful big-bubble formation increased by 1.36 times (p=0.03). Other investigated factors did not significantly influence the rate of achieving a bare DM. The rate of successful big-bubble formation was 79.2% in keratoconus. Among the different factors, recipient sex and trephination size significantly influenced this rate. Females had a lower probability of big-bubble formation, and a large trephination size was associated with an increase in the probability of achieving a bare DM. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  1. Deep Anterior Lamellar Keratoplasty in Keratoconic Patients with versus without Vernal Keratoconjunctivitis.

    Science.gov (United States)

    Feizi, Sepehr; Javadi, Mohammad Ali; Javadi, Fatemeh; Jafarinasab, Mohammad Reza

    2015-01-01

    To compare the clinical outcomes of deep anterior lamellar keratoplasty (DALK) for keratoconus in patients with vernal keratoconjunctivitis (VKC) versus those without VKC. In this retrospective comparative study, records of 262 eyes with keratoconus (Group 1) and 28 keratoconic eyes with VKC (Group 2) that had undergone DALK were compiled. Reviewed parameters included length of follow-up, best-corrected visual acuity (BCVA), refractive error, complications and cumulative graft survival. Mean duration of follow-up was 38.6 ± 20.2 and 34.4 ± 20.9 months in groups 1 and 2, respectively (P = 0.21). Mean post-operative BCVA was 0.19 ± 0.11 and 0.20 ± 0.15 logMAR, in groups 1 and 2 (P = 0.79). BCVA≥20/40 was achieved in 91.6 and 88.5% of eyes in groups 1 and 2, respectively (P = 0.48). Epithelial problems were encountered in 31.3 and 42.9% of operated eyes, respectively (P = 0.16). Vascularization of suture tracts and stitch abscesses were encountered more frequently in the eyes with VKC (P = 0.01 and <0.001, respectively). At the 33-month follow-up examination, rejection-free graft survival rates were 56.0% in group 1 and 33.3% in group 2, with mean durations of 41.0 and 32.1 months, respectively (P = 0.15). Graft survival rates were 98.1% in group 1 and 95.0% in group 2, with mean durations of 88.6 and 88.4 months, respectively (P = 0.74). Clinical outcomes of DALK in keratoconic eyes with VKC were comparable to those in eyes with keratoconus alone. However, complications such as suture tract vascularization and stitch abscesses were more common when VKC coexisted, necessitating closer monitoring.

  2. Intrastromal Corneal Ring Segments for Astigmatism Correction after Deep Anterior Lamellar Keratoplasty

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    Júlio C. D. Arantes

    2017-01-01

    Full Text Available Background. To evaluate the change in corneal astigmatism after intrastromal corneal ring segment (ICRS implantation in keratoconus patients with previous deep anterior lamellar keratoplasty (DALK. Design was a longitudinal, retrospective, interventional study. The study included 25 eyes of 24 patients with keratoconus who had DALK performed at least two years prior to ICRS implantation. All patients had a clear corneal graft with up to 8.00 D of corneal astigmatism and intolerance to contact lenses. The studied parameters were age, sex, corrected distance visual acuity (CDVA, maximum keratometry (K1, minimum keratometry (K2, spherical equivalent, and astigmatism. There was a statistically significant decrease in the postintervention analysis as follows: 3.5 D reduction in K1 (p<0.001; 1.53 D in K2 (p=0.005; and 2.52 D (p<0.001 in the average K. The spherical equivalent reduced from −3.67 D (±2.74 to −0.71 D (±2.35 (p<0.001. The topographic astigmatism reduced from 3.87 D preoperatively to 1.90 D postoperatively (p<0.001. The CDVA improved from 0.33 (±0.10 to 0.20 (±0.09, p<0.001. ICRS implantation is a useful option for the correction of astigmatism after DALK as it yields significant visual, topographic, and refractive results.

  3. Rheophysics of Lamellar Phases Rhéophysiques de phases lamellaires

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    Roux D.

    2006-12-01

    Full Text Available We have developed several techniques to study the effect of shear on complex fluids. These techniques are based on shear cells specially adapted to scattering techniques or transport properties. A brief description of the cells will be given together with the results that can be obtained using these techniques. Exemples on lyotropic systems will be detailed. The effect of shear on lyotropic lamellar phases is studied by light scattering, neutron scattering and microscopic observations. We found three different states of orientation separated with out-of-equilibrium transitions. In the state at very low shear rate, the lamellar phase is, in average, oriented with the layers in the shear plane and a few dislocations remains in the direction of the flow. In the intermediate state, the layers organize themselves into monodisperse multilayer vesicles (MLV whose size is controlled by the shear rate. The last state corresponds to the same orientation than the first one but with no dislocations in the flow direction. The second state of orientation : leading to the MLV structure, is more precisely studied. It is shown that the size of the MLV is fixed by a balance between the viscous and elastic stresses and varies as the inverse square root of the shear rate. A possible mechanism for the formation of this structure is proposed. We show that this structure can be swollen in a solvent leading to a monodisperse emulsion of a lamellar structure in an isotropic liquid. Linear and nonlinear rheological properties are measured and discussed. It is shown that the viscosity is sensitive to the structure and varies of several order of magnitude depending in which phase of orientation the system is. Both shear thickening and shear thinning are described and explanations in terms or orientation transitions are given. The discovery of the oriented to MLV instability is the basis a very efficient process leading to well controlled microcapsules made of surfactant

  4. Cytocomposition of the vitellarium in Khawia sinensis Hsü, 1935 (Cestoda, Caryophyllidea, Lytocestidae): another caryophyllidean species with lamellar bodies and lipids.

    Science.gov (United States)

    Bruňanská, Magdaléna; Drobníková, Petra; Mackiewicz, John S; Nebesářová, Jana

    2013-07-01

    The vitellarium of the invasive caryophyllidean tapeworm Khawia sinensis Hsü, 1935 from carp Cyprinus carpio L. was examined by means of transmission electron microscopy and cytochemical staining for glycogen with periodic acid-thiosemicarbazide-silver proteinate (PA-TSC-SP). A vitellarium consists of numerous follicles of irregular size that are interconnected by a net of vitelline ducts. Vitelline follicles are composed of vitelline cells at various stages of development that are interconnected by interstitial tissue. Vitelline follicles are surrounded by a cytoplasmic sheath associated with an intercellular matrix. Extensive development of the granular endoplasmic reticulum and Golgi complexes are both involved in the production of shell globules/shell globule clusters and characterise cytodifferentiation of vitellocytes. Nuclear and nucleolar transformation lead to the formation and storage of intranuclear glycogen, a feature specific for the Caryophyllidea. Newly observed within the mature vitellocytes of Khawia sp. is the presence of lamellar bodies and a few lipid droplets. These cytoplasmic inclusions first occur in the mature cells within the follicles and persist in the vitelline cells within vitelloducts and intrauterine eggs. Two types of lamellar bodies are detected: regular lamellar-structured body and irregular lamellar-structured body. None of the lamellar bodies are membrane bound. Results of the present study indicate that the formation of lamellar bodies may be closely related to the endoplasmic reticulum or shell globule clusters. Some of the shell globule clusters are transformed into lamellar body clusters. Ultrastructural features of vitellocytes in K. sinensis are compared with those of other monopleuroid, polypleuroid, and strobilated cestodes.

  5. Queratitis lamelar difusa después de un corte incompleto Diffuse lamellar keratitis after incomplete corneal flap cut

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    Yanaisa Riverón Ruiz

    2012-12-01

    Full Text Available La queratitis lamelar difusa es una inflamación estéril de la interfase lamelar que suele presentarse 24 horas después de la realización de la queratomileusis in situ asistida con láser y potencialmente puede comprometer la agudeza visual final. Se presenta un paciente de 25 años de edad con antecedentes de cirugía refractiva corneal mediante queratomileusis in situ con láser en el ojo derecho, que tuvo como complicación durante el acto quirúrgico un corte incompleto. En el posoperatorio inmediato se le diagnosticó una queratitis lamelar difusa. Se aplicó tratamiento local y se obtuvo la recuperación visual total del paciente con estabilidad del defecto refractivo. Esto permite posteriormente realizarle la corrección mediante cirugía refractiva de superficie.The diffuse lamellar keratitis is a sterile swelling of the lamellar interface which arises generally 24 hours after laser in situ keratomileusis and might affect the final visual acuity. A 25 years- old patient with history of corneal refractive surgery by laser in situ keratomileusis on his right eye was reported. He suffered from an incomplete corneal flap cut as complication during the surgical procedure, and a diffuse lamellar keratitis was detected at the immediate postsurgical visit. Total visual recovery and the refractive defect stability were attained through local treatment. This allows further correcting the defect by means of a surface refractive surgery in the future.

  6. Use of a novel lamellar keratoplasty with pleat technique to address the abnormal white-to-white diameter in keratoglobus.

    Science.gov (United States)

    Lockington, David; Ramaesh, Kanna

    2015-02-01

    We describe a novel surgical technique that seeks to address the fundamental mechanical problem of the superiorly and vertically displaced limbus and the corresponding abnormal corneal white-to-white diameter in keratoglobus. A 42-year-old woman had progressive reduction of vision due to hydrops of her right cornea with secondary peripheral corneal perforation due to progressive bilateral keratoglobus. Her visual acuity was hand movements in the right eye, with an uncorrectable refractive error. Pachymetry ranged from 287 μm in the peripheries to 474 μm centrally. The simulated keratometry average was 87 diopters. The surgical technique includes corneal debridement, paracentesis to facilitate manipulation of the cornea, cardinal compression sutures, central anterior lamellar dissection, and mattress sutures to tuck the excess peripheral cornea to create a pleat. This intralamellar tuck formed the subsequent bed to host an anterior lamellar corneal graft. At 1-year review, the best-corrected visual acuity was 6/24 (-2.50/+2.00 ×75 in the right eye). Central corneal pachymetry was 744 μM in the right eye. The simulated keratometry average was 42.4 diopters. This visual improvement and refraction remained stable for 3 years postoperatively. We have demonstrated a modified anterior lamellar keratoplasty with pleat technique to achieve satisfactory visual rehabilitation in extreme keratoglobus. This pleat technique addresses the fundamental structural problem of a vertically displaced limbus in keratoglobus. We highlight the optical illusion of the white-to-white diameter in keratoglobus. We also recommend the baking analogy of muffin to cupcake as a communication aid when explaining the mechanics of surgery to the patient.

  7. Simultaneous topography-guided PRK followed by corneal collagen cross-linking after lamellar keratoplasty for keratoconus

    Directory of Open Access Journals (Sweden)

    Spadea L

    2012-11-01

    Full Text Available Leopoldo Spadea,1 Marino Paroli21University of L’Aquila, Department of Biotechnological and Applied Clinical Sciences, Eye Clinic, L’Aquila, 2La Sapienza University, Department of Biotechnology and Medical-Surgical Sciences, Latina, ItalyBackground: The purpose of this paper is to report the results of using combined treatment of customized excimer laser-assisted photorefractive keratectomy (PRK and prophylactic corneal collagen crosslinking (CXL for residual refractive error in a group of patients who had previously undergone lamellar keratoplasty for keratoconus.Methods: The study included 14 eyes from 14 patients who had originally been treated for keratoconus in one eye by excimer laser-assisted lamellar keratoplasty (ELLK, and subsequently presented with residual ametropia (-6.11 D ± 2.48, range -2.50 to -9.50. After a mean 40.1 ± 12.4 months since ELLK they underwent combined simultaneous corneal regularization treatment with topographically guided transepithelial excimer laser PRK (central corneal regularization and corneal CXL induced by riboflavin-ultraviolet A.Results: After a mean 15 ± 6.5 (range 6–24 months, all eyes gained at least one Snellen line of uncorrected distance visual acuity (range 1–10. No patient lost lines of corrected distance visual acuity, and four patients gained three lines of corrected distance visual acuity. Mean manifest refractive spherical equivalent was -0.79 ± 2.09 (range +1 to -3.0 D, and topographic keratometric astigmatism was 5.02 ± 2.93 (range 0.8–8.9 D. All the corneas remained clear (haze < 1.Conclusion: The combination of customized PRK and corneal CXL provided safe and effective results in the management of corneal regularization for refractive purposes after ELLK for keratoconus.Keywords: corneal collagen crosslinking, excimer laser-assisted lamellar keratoplasty, photorefractive keratectomy

  8. Artisan iris-fixated toric phakic intraocular lens for the correction of high astigmatism after deep anterior lamellar keratoplasty.

    Science.gov (United States)

    Al-Dreihi, Madonna G; Louka, Bachar I; Anbari, Anas A

    2013-01-01

    We report the refractive correction of high astigmatism in one eye of a 23-year-old woman following deep anterior lamellar keratoplasty (DALK) using an Artisan iris-fixated, toric, phakic intraocular lens (IOL). One year after implantation, uncorrected and corrected distance visual acuities were both 20/25, refraction was -1.00 D cylinder, and the endothelial cell count was 1827 cells/mm(2). Iris-fixated phakic IOLs are not recommended for every postkeratoplasty patient with high refractive error; however, this procedure can offer good outcomes in carefully selected cases of previous DALK.

  9. Stability of vision, topography, and endothelial cell density from 1 year to 2 years after deep lamellar endothelial keratoplasty surgery.

    Science.gov (United States)

    Ousley, Paula J; Terry, Mark A

    2005-01-01

    To evaluate whether the visual, topographic, and endothelial cell count results observed 1 year after deep lamellar endothelial keratoplasty (DLEK) surgery remain stable up to 2 years after surgery. Prospective, noncomparative, interventional case series. Twenty eyes of 20 patients with corneal edema from Fuchs' endothelial dystrophy. Deep lamellar endothelial keratoplasty endothelial replacement surgery, with a 9.0-mm or 9.5-mm scleral access incision and a specialized intrastromal trephine, was performed. Snellen visual acuities, corneal topography, and endothelial cell counts were prospectively measured preoperatively and 1 year and 2 years after DLEK. Uncorrected and best spectacle-corrected visual acuity (BSCVA), refractive and topographic astigmatism, mean corneal curvature, topographic regularity and symmetry, and endothelial cell density. At 1 year postoperatively, BSCVA averaged 20/50 (range, 20/25-20/200), spherical equivalents (SE) averaged -0.194+/-1.521 diopters (D), manifest refraction (MR) astigmatism averaged 2.04+/-1.05 D (range, 0.0-4.0 D), topographic astigmatism averaged 2.3+/-1.1 D, mean corneal curvature was 43.2+/-1.8 D, the surface regularity index (SRI) averaged 1.16+/-0.41, and the surface asymmetry index (SAI) averaged 1.05+/-1.09. At 2 years postoperatively, BSCVA averaged 20/48 (range, 20/25-20/200), SE averaged -0.369+/-1.267 D, MR astigmatism averaged 1.76+/-0.66 D (range, 0.75-3.0 D), topographic astigmatism averaged 2.4+/-1.1 D, mean corneal curvature was 43.6+/-1.8 D, the SRI averaged 1.13+/-0.44, and the SAI averaged 0.76+/-0.59. There was no significant change in visual or topographic parameters between 1 year and 2 years postoperatively (P>0.05). Endothelial cell counts averaged 2335+/-468 cells/mm(2) at 1 year and 2151+/-457 cells/mm(2) at 2 years postoperatively (P = 0.041). Deep lamellar endothelial keratoplasty provides stable refractions, corneal topography, and endothelial cell densities as long as 2 years after surgery

  10. Three-Point Bending Fracture Behavior of Single Oriented Crossed-Lamellar Structure in Scapharca broughtonii Shell.

    Science.gov (United States)

    Ji, Hong-Mei; Zhang, Wen-Qian; Wang, Xu; Li, Xiao-Wu

    2015-09-15

    The three-point bending strength and fracture behavior of single oriented crossed-lamellar structure in Scapharca broughtonii shell were investigated. The samples for bending tests were prepared with two different orientations perpendicular and parallel to the radial ribs of the shell, which corresponds to the tiled and stacked directions of the first-order lamellae, respectively. The bending strength in the tiled direction is approximately 60% higher than that in the stacked direction, primarily because the regularly staggered arrangement of the second-order lamellae in the tiled direction can effectively hinder the crack propagation, whereas the cracks can easily propagate along the interfaces between lamellae in the stacked direction.

  11. Equine insulin receptor and insulin-like growth factor-1 receptor expression in digital lamellar tissue and insulin target tissues.

    Science.gov (United States)

    Kullmann, A; Weber, P S; Bishop, J B; Roux, T M; Norby, B; Burns, T A; McCutcheon, L J; Belknap, J K; Geor, R J

    2016-09-01

    Hyperinsulinaemia is implicated in the pathogenesis of endocrinopathic laminitis. Insulin can bind to different receptors: two insulin receptor isoforms (InsR-A and InsR-B), insulin-like growth factor-1 receptor (IGF-1R) and InsR/IGF-1R hybrid receptor (Hybrid). Currently, mRNA expression of these receptors in equine tissues and the influence of body type and dietary carbohydrate intake on expression of these receptors is not known. The study objectives were to characterise InsR-A, InsR-B, IGF-1R and Hybrid expression in lamellar tissue (LT) and insulin responsive tissues from horses and examine the effect of dietary nonstructural carbohydrate (NSC) on mRNA expression of these receptors in LT, skeletal muscle, liver and two adipose tissue (AT) depots of lean and obese ponies. In vivo experiment. Lamellar tissue samples were evaluated by quantitative reverse transcription polymerase chain reaction (RT-qPCR) for receptor mRNA expression (n = 8) and immunoblotting for protein expression (n = 3). Archived LT, skeletal muscle, liver and AT from lean and obese mixed-breed ponies fed either a low (~7% NSC as dry matter; 5 lean, 5 obese) or high NSC diet (~42% NSC as dry matter; 6 lean, 6 obese) for 7 days were evaluated by RT-qPCR to determine the effect of body condition and diet on expression of the receptors in different tissues. Significance was set at P≤0.05. Lamellar tissue expresses both InsR isoforms, IGF-1R and Hybrid. LT IGF-1R gene expression was greater than either InsR isoform and InsR-A expression was greater than InsR-B (P≤0.05). Obesity significantly lowered IGF-1R, InsR-A and InsR-B mRNA expression in LT and InsR-A in tailhead AT. High NSC diet lowered expression of all three receptor types in liver; IGF-1R and InsR-A in LT and InsR-A in tailhead AT. Lamellar tissue expresses IGF-1R, InsR isoforms and Hybrids. The functional characteristics of these receptors and their role in endocrinopathic laminitis warrants further investigation. © 2015 EVJ

  12. Animal MRI Core

    Data.gov (United States)

    Federal Laboratory Consortium — The Animal Magnetic Resonance Imaging (MRI) Core develops and optimizes MRI methods for cardiovascular imaging of mice and rats. The Core provides imaging expertise,...

  13. Anwar versus Melles deep anterior lamellar keratoplasty for keratoconus: a prospective randomized clinical trial.

    Science.gov (United States)

    Baradaran-Rafii, Alireza; Eslani, Medi; Sadoughi, Mohammad-Mehdi; Esfandiari, Hamed; Karimian, Farid

    2013-02-01

    To compare the outcomes of 2 techniques (Anwar vs. Melles) of deep anterior lamellar keratoplasty (DALK) in patients with keratoconus. Randomized, double-blind clinical trial. Fifty-seven eyes of 57 patients 20 to 35 years of age were enrolled. Patients with clinical diagnosis of keratoconus who were contact lens intolerant and whose corrected distance visual acuity (CDVA) was less than 20/80 were enrolled. Eligible eyes were allocated randomly into 2 groups: the Anwar technique (23 eyes) or the Melles technique (25 eyes). The primary outcome measure was CDVA. Secondary outcomes were spherical equivalent, contrast sensitivity, corneal aberrations, corneal biomechanical properties, endothelial cell count, and central corneal thickness. All outcomes were compared 15 months after surgery. The CDVA was 0.17 ± 0.09 logarithm of the minimum angle of resolution (logMAR) units and 0.18 ± 0.11 logMAR units in the Anwar and Melles groups, respectively (P = 0.803). Spherical equivalent was -1.82 ± 2.7 diopters (D) and -2.69 ± 3.94 D in the Anwar and Melles groups, respectively (P = 0.155). Overall, the difference in photopic and mesopic contrast sensitivity function between the 2 groups was statistically significant (P0.05 for all parameters). Corneal hysteresis was not significantly different between the 2 groups (9.9 ± 0.8 vs. 9.9 ± 0.6; P = 0.606). The corneal resistance factor was 10.02 ± 0.8 and 10.13 ± 0.76 (P = 0.509). There was no significant difference in percentage of endothelial cell loss between the 2 groups (1 ± 2% vs. 1 ± 3% in the Anwar and Melles groups, respectively; P = 0.869). Mean central corneal thickness was 525.56 ± 47.87 μm versus 504.64 ± 54.20 μm in the Anwar and Melles groups, respectively (P = 0.155). The Anwar and Melles techniques of DALK have comparable visual acuity and refractive outcomes, aberrometric profiles, biomechanical properties, corneal thicknesses, and endothelial cell densities. However, patients who underwent the

  14. Deep Anterior Lamellar Keratoplasty Using the Big-Bubble Technique in Keratoconus

    Directory of Open Access Journals (Sweden)

    Mohammad-Ali Javadi

    2009-01-01

    Full Text Available

    PURPOSE: To evaluate the visual outcomes and complications of deep anterior lamellar keratoplasty (DALK using the big-bubble technique in patients with keratoconus. METHODS: In this case series, 104 eyes of 99 patients with moderate to advanced keratoconus underwent DALK. All subjects were contact lens intolerant or had unacceptable spectacle-corrected visual acuity. DALK was performed using the big-bubble technique. Full thickness donor corneas devoid of Descemet's membrane (DM were sutured to the recipient bed. Best spectacle-corrected visual acuity (BSCVA, refractive status, and intra- and postoperative complications were evaluated. RESULTS: Patients were male in 62.5%. Mean age of patients was 26.2±7.79 (range 15-46 years at the time of DALK and were followed for 23.07±8.1 (range 9-42 months. Mean BSCVA increased from 1.23±0.4 logMAR to 0.26±0.2 logMAR at final follow-up (P < 0.001. Postoperative mean spherical equivalent refractive error and refractive and keratometric astigmatism were -3.41±3.1 D, 3.07±2.4 D, and 3.64±2.2 D, respectively. Bared DM was achieved in 86 (82.7% eyes. Main complications encountered included filamentary keratitis (19.2%, non-endothelial graft rejection (14.4%, and suture abscess (10.6%. CONCLUSIONS: DALK using the big-bubble technique appears to be a safe and effective procedure in

  15. Self-structuring of lamellar bridged silsesquioxanes with long side spacers.

    Science.gov (United States)

    Fernandes, Mariana; Nobre, Sónia S; Xu, Qinghong; Carcel, Carole; Cachia, Jean Nicolas; Cattoën, Xavier; Sousa, José M; Ferreira, Rute A S; Carlos, Luís D; Santilli, Celso V; Wong Chi Man, Michel; Bermudez, Verónica de Zea

    2011-09-22

    Diurea cross-linked bridged silsesquioxanes (BSs) C(10)C(n)C(10) derived from organosilane precursors, including decylene chains as side spacers and alkylene chains with variable length as central spacers (EtO)(3)Si-(CH(2))(10)-Y-(CH(2))(n)-Y-(CH(2))(10)-Si(OEt)(3) (n = 7, 9-12; Y = urea group and Et = ethyl), have been synthesized through the combination of self-directed assembly and an acid-catalyzed sol-gel route involving the addition of dimethylsulfoxide (DMSO) and a large excess of water. This new family of hybrids has enabled us to conclude that the length of the side spacers plays a unique role in the structuring of alkylene-based BSs, although their morphology remains unaffected. All the samples adopt a lamellar structure. While the alkylene chains are totally disordered in the case of the C(10)C(7)C(10) sample, a variable proportion of all-trans and gauche conformers exists in the materials with longer central spacers. The highest degree of structuring occurs for n = 9. The inclusion of decylene instead of propylene chains as side spacers leads to the formation of a stronger hydrogen-bonded urea-urea array as evidenced by two dimensional correlation Fourier transform infrared spectroscopic analysis. The emission spectra and emission quantum yields of the C(10)C(n)C(10) materials are similar to those reported for diurea cross-linked alkylene-based BSs incorporating propylene chains as side spacers and prepared under different experimental conditions. The emission of the C(10)C(n)C(10) hybrids is ascribed to the overlap of two distinct components that occur within the urea cross-linkages and within the siliceous nanodomains. Time-resolved photoluminescence spectroscopy has provided evidence that the average distance between the siliceous domains and the urea cross-links is similar in the C(10)C(n)C(10) BSs and in oxyethylene-based hybrid analogues incorporating propylene chains as side spacers (diureasils), an indication that the longer side chains in the

  16. Self-Propagating Combustion Triggered Synthesis of 3D Lamellar Graphene/BaFe12O19 Composite and Its Electromagnetic Wave Absorption Properties

    Science.gov (United States)

    Zhao, Tingkai; Ji, Xianglin; Jin, Wenbo; Yang, Wenbo; Peng, Xiarong; Duan, Shichang; Dang, Alei; Li, Hao; Li, Tiehu

    2017-01-01

    The synthesis of 3D lamellar graphene/BaFe12O19 composites was performed by oxidizing graphite and sequentially self-propagating combustion triggered process. The 3D lamellar graphene structures were formed due to the synergistic effect of the tremendous heat induced gasification as well as huge volume expansion. The 3D lamellar graphene/BaFe12O19 composites bearing 30 wt % graphene present the reflection loss peak at −27.23 dB as well as the frequency bandwidth at 2.28 GHz (graphene structures could consume the incident waves through multiple reflection and scattering within the layered structures, prolonging the propagation path of electromagnetic waves in the absorbers. PMID:28336889

  17. Isolated rat alveolar type II cells protrude intracellular lamellar bodies by forming bubble-like structures during surfactant secretion.

    Science.gov (United States)

    Ogasawara, Rie; Yoshida, Yasuo; Tohyama, Koujiro; Satoh, Yoh-ichi; Suwabe, Akira

    2009-02-01

    Pulmonary surfactant is synthesized and secreted by pulmonary alveolar type II epithelial cells (type II cells). It passes through the alveolar lining fluid and adsorbs to the air-liquid interface. The process from secretion to adsorption is not yet entirely understood. To acquire a detailed understanding of this process, we used multiple observations of type II cells isolated from rat lungs under electron microscopy (EM) and confocal laser scanning microscopy (CLSM). Transmission EM observation demonstrated a loosening process of the intracellular lamellar bodies from the inside to the outside of the cell. Scanning EM observation revealed bubble-like protrusions from the cell surface, and differential interference contrast microscopy illustrated the protrusions expanding with time. CLSM observation with FM 1-43, a fluorescent membrane probe, revealed that the bubble-like protrusions were composed of phospholipids. Thus, we have demonstrated that isolated rat type II cells protrude intracellular lamellar bodies by forming bubble-like structures, possibly enabling them to adsorb to the air-liquid interface directly. These observations suggest a new mechanism for surfactant secretion from type II cells.

  18. Complex macrophase-separated nanostructure induced by microphase separation in binary blends of lamellar diblock copolymer thin films.

    Science.gov (United States)

    Zhang, Jianqi; Posselt, Dorthe; Smilgies, Detlef-M; Perlich, Jan; Kyriakos, Konstantinos; Jaksch, Sebastian; Papadakis, Christine M

    2014-09-01

    The nanostructures of thin films spin-coated from binary blends of compositionally symmetric polystyrene-b-polybutadiene (PS-b-PB) diblock copolymer having different molar masses are investigated by means of atomic force microscopy (AFM) and grazing-incidence small-angle X-ray scattering (GISAXS) after spin-coating and after subsequent solvent vapor annealing (SVA). In thin films of the pure diblock copolymers having high or low molar mass, the lamellae are perpendicular or parallel to the substrate, respectively. The as-prepared binary blend thin films feature mainly perpendicular lamellae in a one-phase state, indicating that the higher molar mass diblock copolymer dominates the lamellar orientation. The lamellar thickness decreases linearly with increasing volume fraction of the low molar mass diblock copolymer. After SVA, well-defined macrophase-separated nanostructures appear, which feature parallel lamellae near the film surface and perpendicular ones in the bulk. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Corneal biomechanical properties in eyes with no previous surgery, with previous penetrating keratoplasty and with deep anterior lamellar keratoplasty.

    Science.gov (United States)

    Acar, Banu Torun; Akdemir, Mehmet Orcun; Acar, Suphi

    2013-01-01

    To compare the biomechanical properties of the cornea in eyes with no previous surgery, with keratoconus with previous penetrating keratoplasty (PK) and with keratoconus with previous deep anterior lamellar keratoplasty (DALK) using the Reichert Ocular Response Analyzer (ORA). One hundred twenty eyes of 120 patients were included in this prospective comparative study. Forty eyes were with no previous ocular surgery (group 1), 40 eyes were with previous PK for keratoconus (group 2), and 40 eyes were with previous DALK for keratoconus (group 3). Corneal hysteresis (CH) and the corneal resistance factor (CRF) were measured with ORA. The CH and CRF values in group 2 were significantly lower than in group 1 and group 3 (p = 0.001). The CH and CRF values were similar in group 1 and group 3. There was no statistically significant difference between group 1 and 3. Although the post-PK keratoconus cornea has weaker biomechanical properties, post-DALK keratoconus cornea is similar to normal cornea. A cornea weakened by keratoconus can be strengthened with lamellar keratoplasty.

  20. Electrolyte effects on the stability of nematic and lamellar lyotropic liquid crystal phases: colligative and ion-specific aspects.

    Science.gov (United States)

    Dawin, Ute C; Lagerwall, Jan P F; Giesselmann, Frank

    2009-08-20

    We investigated the electrolyte effects on the stability of nematic and lamellar lyotropic liquid crystalline (LLC) phases formed by the simple anionic surfactant cesium pentadecafluorooctanoate (CsPFO) in water. To the lyotropic guest phase, at the constant CsPFO-mass fraction of 0.55, the series of electrolytes LiCl, NaCl, KCl, CsCl, CsI, and Cs(2)SO(4), respectively, was added at concentrations ranging from 0.5 to 2.5 mol %. With increasing electrolyte concentration two substantially different effects were observed. At low concentrations all added electrolytes caused an increase of the thermal stability of the LLC phases, favoring the lamellar phase over the nematic phase. This behavior is, at least qualitatively, understood within the packing parameter model. The extent of the stabilization clearly depends on the chemical nature of the added cation. For a given cation, however, the effect is colligative, i.e., independent of the chemical nature of the added anion. At higher salt concentrations a salting-out-like phase separation was induced. This effect is clearly ion-specific as the salting-out concentration varied for each cation following the order of the Hofmeister series for cations.

  1. Biochemical Change at the Setting-up of the Crossed-Lamellar Layer in Nerita undata Shell (Mollusca, Gastropoda

    Directory of Open Access Journals (Sweden)

    Julius Nouet

    2012-03-01

    Full Text Available Nerita undata is a marine gastropod, the shell of which consists of an external layer composed of very fine, long and undulating calcite prisms, and of an internal aragonite crossed-lamellar layer. As for any Ca-carbonate shell, both layers are composite materials, resulting from the  sub-micrometric association of organic macromolecules with the mineral phase. But at the transition between the two layers, in situ synchrotron-based mapping using μ-XANES spectroscopy performed at the S K-edge and SR-FTIR spectroscopy reveals that biochemical compositions change correlatively with the mineral phase, such as displayed by the distribution of sulfur-containing organic compounds (S-polysaccharides or S-amino acids and organic molecular groups (amide I and II bands. These results highlight the complex change of secretory activity operated by the mineralizing tissue (the mollusk mantle between these two parts of the shell, which is suspected to minutely control the setting-up of the crossed-lamellar microstructural pattern over the calcite prisms—A not so straightforward feature.

  2. k -core covers and the core

    NARCIS (Netherlands)

    Sanchez-Rodriguez, E.; Borm, P.; Estevez Fernandez, M.A.; Fiestras-Janeiro, M.G.; Mosquera, M.A.

    2015-01-01

    This paper extends the notion of individual minimal rights for a transferable utility game (TU-game) to coalitional minimal rights using minimal balanced families of a specific type, thus defining a corresponding minimal rights game. It is shown that the core of a TU-game coincides with the core of

  3. k-core covers and the core

    NARCIS (Netherlands)

    Sanchez-Rodriguez, E.; Borm, Peter; Estevez-Fernandez, A.; Fiestras-Janeiro, G.; Mosquera, M.A.

    This paper extends the notion of individual minimal rights for a transferable utility game (TU-game) to coalitional minimal rights using minimal balanced families of a specific type, thus defining a corresponding minimal rights game. It is shown that the core of a TU-game coincides with the core of

  4. Inner Stucture of Thin Films of Lamellar Poly(styrene-b-butadiene) Diblock Copolymers as revealed by Grazing-Incidence Small-Angle Scattering

    DEFF Research Database (Denmark)

    Busch, Peter; Posselt, Dorthe; Smilgies, Detlef-Matthias

    2007-01-01

    The lamellar orientation in supported, thin films of poly(styrene-b-butadiene) (P(S-b-B)) depends on block copolymer molar mass. We have studied films from nine block copolymer samples with molar masses between 13.9 and 183 kg/mol using grazing-incidence small-angle X-ray scattering (GISAXS) and ...

  5. Spectral phasor analysis of LAURDAN fluorescence in live A549 lung cells to study the hydration and time evolution of intracellular lamellar body-like structures

    DEFF Research Database (Denmark)

    Malacrida, Leonel; Astrada, Soledad; Briva, Arturo

    2016-01-01

    Using LAURDAN spectral imaging and spectral phasor analysis we concurrently studied the growth and hydration state of subcellular organelles (lamellar body-like, LB-like) from live A549 lung cancer cells at different post-confluence days. Our results reveal a time dependent two-step process...

  6. Contrast sensitivity in deep anterior lamellar keratoplasty versus penetrating keratoplasty Sensibilidade ao contraste entre transplante lamelar anterior profundo e transplante penetrante de córnea

    Directory of Open Access Journals (Sweden)

    Carlos Anchieta Castro Cardoso da Silva

    2007-01-01

    Full Text Available PURPOSE: To compare the measurements of contrast sensitivity at a distance in patients submitted to penetrating keratoplasty versus patients submitted to deep anterior lamellar keratoplasty for keratoconus treatment. METHODS: Contrast sensitivity of 15 subjects submitted to penetrating keratoplasty and 15 subjects submitted to deep anterior lamellar keratoplasty have been analyzed through the Functional Acuity Contrast Test (F.A.C.T® 301. RESULTS: There was no statistically significant difference between the measurements for penetrating keratoplasty and deep anterior lamellar keratoplasty. CONCLUSION: Contrast sensitivity was similar among the subjects submitted to penetrating keratoplasty and to deep anterior lamellar keratoplasty for keratoconus treatment.OBJETIVO: Comparar as medidas de sensibilidade ao contraste à distância entre pacientes submetidos à ceratoplastia penetrante e pacientes submetidos à ceratoplastia lamelar anterior profunda para tratamento do ceratocone. MÉTODOS: Sensibilidades ao contraste de 15 pacientes submetidos à ceratoplastia penetrante e de 15 pacientes submetidos à ceratoplastia lamelar anterior profunda foram analisadas através do Functional Acuity Contrast Test (F.A.C.T® 301. RESULTADOS: Não existiu diferença estatisticamente significante entre as medidas em ceratoplastia penetrante e ceratoplastia lamelar anterior profunda. CONCLUSÃO: Sensibilidade ao contraste foi similar entre os pacientes submetidos à ceratoplastia penetrante e à ceratoplastia lamelar anterior profunda para tratamento do ceratocone.

  7. Oral buccal mucous membrane allograft with a corneal lamellar graft for the repair of Boston type 1 keratoprosthesis stromal melts.

    Science.gov (United States)

    Ziai, Setareh; Rootman, David S; Slomovic, Allan R; Chan, Clara C

    2013-11-01

    To describe a surgical technique to repair Boston type 1 keratoprosthesis (KPro)-related corneal melts. Technique description and review of 3 representative cases. After harvesting the buccal mucosa from the patient's inner lower lip, the exposed area of the KPro back plate is prepared for repair by adequate exposure and removal of necrotic tissue. The area is then covered with a lamellar patch of cornea secured in place with interrupted 10-0 nylon sutures, followed by a thin layer of buccal mucosa secured in place with interrupted 8-0 vicryl sutures. This technique provides surgeons with a method to repair KPro-related corneal melts when there is a conjunctival deficiency.

  8. Irregularities of crystallographic orientation and residual stresses in the crossed-lamellar shell as a natural functionally graded material.

    Science.gov (United States)

    Bonarski, Jan T; Checa, Antonio G; Rodriguez-Navarro, Alejandro; Tarkowski, Leszek; Wajda, Wojciech

    2015-12-06

    The microstructures of different groups of molluscs are characterized by preferential orientations of crystallites (texture), leading to a significant anisotropy of the physical properties of the shells. A complementary characteristic, usually neglected, is the distribution of the residual stresses existing within the shell wall. By means of X-ray diffraction, we study the distribution of stresses with thickness in the shell wall of the gastropod Conus marmoreus, which has a microstructure of the crossed-lamellar type. The results revealed an extraordinary texture inhomogeneity and the existence of tensional residual stresses along the shell thickness, the origins of which are unknown. Some of the observed changes in textural parameters and stresses coincide with the transitions between shell layers, although other features are of unknown origin. Our results provide insight into the microstructural regularities that govern the mesoscale construction of shells, such as that of C. marmoreus. © 2015 The Author(s).

  9. Corneal Biomechanical Properties After Penetrating Keratoplasty or Deep Anterior Lamellar Keratoplasty Using the Ocular Response Analyzer: A Meta-Analysis.

    Science.gov (United States)

    Jiang, Min-Shan; Zhu, Jing-Yuan; Li, Xue; Zhang, Nan-Nan; Zhang, Xue-Dian

    2017-03-01

    To evaluate the corneal biomechanical properties of patients who have undergone penetrating keratoplasty (PK) or deep anterior lamellar keratoplasty (DALK) using the ocular response analyzer. Stata 13.0 SE was used for this meta-analysis. Studies in the literature that focused on corneal hysteresis (CH) or corneal resistance factor (CRF) after PK or DALK were retrieved by searching PubMed, Embase, Ovid, and Cochrane databases. We present the results as weighted mean difference (WMD) with a corresponding 95% confidence interval (CI). Eight studies with a total of 750 eyes were included in the post-PK versus control group, and 4 studies with a total of 218 eyes were included in the post-DALK versus control group. The pooled results showed that CH and CRF were significantly reduced (P corneal transplantation with DALK than PK.

  10. A comparative review between the updated models of Brazilian, United Kingdom and American eye banks and lamellar transplants

    Directory of Open Access Journals (Sweden)

    Gustavo Victor

    2014-12-01

    Full Text Available The corneal transplantation (CT is the most commonly performed type of transplant in the world and the Eye Banks are organizations whose capture, evaluate, preserve, store and distribute ocular tissues. With the evolution of surgical techniques and equipment for CT, the BOs had to evolve to keep up with these requirements. This evolution goes from tissues capture techniques, donating money and clarification to the patient (e.g. internet-based, use of current equipment for more adequate tissues supply for the most current surgical techniques, integration of BOs of certain country and real-time management of stocks of ocular tissues, and adequacy of laws that manage the entire process. This review aims to make a comparative review between the updated models of Brazilian, United Kingdon and American Eye Banks. Like, check what the trend towards lamellar transplants in these three countries.

  11. DNA hosted and aligned in aqueous interstitia of a lamellar liquid crystal – a membrane–biomacromolecule interaction model system

    KAUST Repository

    Carlsson, Nils

    2013-01-01

    We report that DNA molecules can be intercalated and macroscopically oriented in the aqueous interstitia of a lyotropic lamellar liquid crystal. Using UV-vis linear dichroism and fluorescence spectroscopy we show that double-stranded oligonucleotides (25 base pairs) in the water-octanoate-decanol system remain base-paired in the B conformation and are confined in two dimensions, with the helix axis preferentially parallel to the lipid bilayer surfaces but free to rotate within this plane. The degree of helix confinement and the corresponding 2-D orientation can be improved by decreasing the thickness of the water interstitia via the fraction of water in the ternary mixture. Not surprisingly, the corresponding single-stranded oligonucleotides are not aligned, with their persistence length being short in comparison to the lamellar interstitium thickness. We propose this as a model system for studying interactions of DNA-ligand complexes near a lipid bilayer membrane which we demonstrate by using dye probes that are either covalently attached to one end of the oligonucleotide or reversibly bound by intercalation between the base pairs. Three cationic dyes, all strongly bound by intercalation to DNA when free in solution, are found to not bind to DNA but to prefer the membrane surface. The covalently attached Cy5 also binds to the bilayer while Cy3 tends to end-stack to the oligonucleotide duplex. The orientation of Cy5 parallel to the membrane indicates that electrostatic surface binding predominates over insertion into the hydrophobic interior of the membrane. Anionic and zwitterionic dyes (FAM and ROX) are found to remain randomly oriented in the water between the lipid bilayer surfaces. © The Royal Society of Chemistry.

  12. Electric field effects on alignment of lamellar structures in diblock copolymer thin films studied by neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Xiuli

    2006-12-07

    We investigated the lamellar orientation in thin films of a diblock copolymer P(S-b-MMA), under competing effects of surface interactions and an electric field applied perpendicular to the substrate. The surface effects tend to align the lamellae parallel to the substrate while the electric field tends to align the lamellae perpendicular to the substrate. Using neutron reflectivity, neutron diffuse scattering, and neutron small-angle scattering, we achieved a quantitative analysis of the internal structure of the films. Film thickness was found to play a non-trivial role in determining the structure of the films. A complete alignment by the surface effects was observed in the thinner films by annealing. The parallel orientation remains stable even if an electric field as strong as 40 V/{mu}m is applied. In the thicker films, a mixed orientation with boundary layers parallel and the central part partially perpendicular to the substrate was observed after annealing. The mixed orientation becomes unstable under a small compressive stress, and will be converted into a completely parallel orientation. The parallel orientation induced by the compressive stress remains stable as long as the electric field is weaker than several ten V/{mu}m. Only a field of about 40 V/{mu}m is able to stabilize the above mentioned mixed orientation. A fully perpendicular orientation was never observed in our experiments. Diffuse scattering shows a mosaic structure in the absence of an electric field, whose mosaicity will be increased by the torque exerted by an electric field. The lateral correlation length of the lamellar domains is estimated as 1-2 {mu}m. Limited by the small q{sub x}-range we have used, a clear statement on the existence of the electric-field-induced structural undulations predicted by the Onuki's theory cannot be made from our experiments. (orig.)

  13. Sub-10nm lines and spaces patterning using grapho-epitaxial directed self-assembly of lamellar block copolymers

    Science.gov (United States)

    Seino, Yuriko; Sato, Hironobu; Kasahara, Yusuke; Minegishi, Shinya; Miyagi, Ken; Kubota, Hitoshi; Kanai, Hideki; Kodera, Katsuyoshi; Shiraishi, Masayuki; Kihara, Naoko; Kawamonzen, Yoshiaki; Tobana, Toshikatsu; Kobayashi, Katsutoshi; Yamano, Hitoshi; Azuma, Tsukasa; Nomura, Satoshi

    2016-04-01

    Our target at EIDEC is to study the feasibility of directed self-assembly (DSA) technology for semiconductor device manufacturing through electrical yield verification by development of such as process, material, metrology, simulation and design for DSA. We previously developed a grapho/chemo-hybrid coordinated line epitaxial process for sub-15-nm line-and-space (L/S) patterning using polystyrene-block-poly(methyl methacrylate) lamellar block copolymers (BCPs)1- 3. Electrical yield verification results showed that a 30% open yield was successfully achieved with a metal wire line length of 700 μm 4. In the next stage of the evaluation, a sub-10-nm L/S DSA patterning process based on graphoepitaxial DSA of 20-nm lamellar period organic BCPs was developed based on neutral layer and guide space width optimization. At a 30-nm guide height, problems such as BCP overflow and DSA line shorts were observed after the dry development. At a 60-nm guide height, grid-like short defects were observed under dry development shallow etch conditions and sub-10-nm L/S patterns were formed under optimized etch conditions with a suitable BCP film thickness margin. The process performance was evaluated in terms of defects and critical dimension measurements using an electron beam inspection system and critical dimension-scanning electron microscope metrology. The main DSA defects were short defects, and the spatial roughness appeared to be caused by the periodic pitches of these short defects and the guide roughness. We successfully demonstrated the fabrication of sub-10-nm metal wires consists of L/S, pad, connect and cut patterns with controlled alignment and stack structure through lithography, etching and CMP process on a 300- mm wafer using the fully integrated DSA process and damascene processing.

  14. Does the type of suturing technique used affect astigmatism after deep anterior lamellar keratoplasty in keratoconus patients?

    Directory of Open Access Journals (Sweden)

    Acar BT

    2011-04-01

    Full Text Available Banu Torun Acar, Ece Turan Vural, Suphi AcarHaydarpasa Numune Education and Research Hospital, Ophthalmology Clinic, Istanbul, TurkeyPurpose: To compare the effect of three different suturing techniques on astigmatism after deep anterior lamellar keratoplasty (DALK in patients with keratoconus.Methods: In this retrospective study, 54 eyes of 54 patients with advanced keratoconus underwent DALK with three suturing techniques: single running, interrupted running, and combined interrupted and running. Postkeratoplasty astigmatism was evaluated during examinations 1, 3, and 6 months postoperatively and 2 months after completing suture removal.Results: Twenty-four eyes had single running sutures, 16 eyes had interrupted sutures, and in 14 eyes the suturing technique used was combined interrupted and running sutures. Mean age was 25.6 ± 5.9 years, 27.3 ± 6.8 years, and 26.5 ± 5.7 years (P = 0.422, and postoperative astigmatism 1 month after surgery was 3.79 ± 1.19 D, 5.56 ± 1.78 D, and 4.21 ± 1.55 D in the three groups, respectively (P = 0.012. However, 2 months after completing the suture removal, final postoperative astigmatism was 3.43 ± 1.44 D, 3.87 ± 1.38 D, and 3.71 ± 1.46 D (P = 0.846. Final astigmatism less than 4 D was seen in 18 cases (75% in the single running group, nine cases (56.2% in the interrupted running group, and nine cases (64.2% in the combined interrupted and running group (P = 0.08.Conclusion: Postkeratoplasty astigmatism is comparable with three different suturing techniques used in patients with keratoconus after completing suture removal in DALK. Due to earlier suture removal in DALK, the type of suturing technique used is not considerably important.Keywords: astigmatism, deep anterior lamellar keratoplasty, suturing technique

  15. Multi-core Microprocessors

    Indian Academy of Sciences (India)

    programming and computer fundamentals. His current research interests are parallel computing and history of computing. Multi-core microprocessor is an interconnected set of inde- pendent processors called cores integrated on a single sili- con chip. These processing cores communicate and cooperate with one another ...

  16. Core Competence and Education.

    Science.gov (United States)

    Holmes, Gary; Hooper, Nick

    2000-01-01

    Outlines the concept of core competence and applies it to postcompulsory education in the United Kingdom. Adopts an educational perspective that suggests accreditation as the core competence of universities. This economic approach suggests that the market trend toward lifetime learning might best be met by institutions developing a core competence…

  17. Large area, soft crystalline thin films of N,N' ,N''> -trialkyltriazatriangulenium salts with homeotropic alignment of the discotic cores in a lamellar lattice

    DEFF Research Database (Denmark)

    Just Sørensen, Thomas; Hildebrandt, Christoffer B.; Elm, Jonas

    2012-01-01

    N,N' ,N'' -Trialkyltriazatriangulenium (R-TATA+) tetrafluoroborate (BF4) salts form highly ordered thin films directly when spin-cast onto rotating substrates. The homogeneous and crystalline thin films show macroscopic order over centimetres. The crystal structures of the R-TATA$BF4 salts are in...

  18. Core stability exercise principles.

    Science.gov (United States)

    Akuthota, Venu; Ferreiro, Andrea; Moore, Tamara; Fredericson, Michael

    2008-02-01

    Core stability is essential for proper load balance within the spine, pelvis, and kinetic chain. The so-called core is the group of trunk muscles that surround the spine and abdominal viscera. Abdominal, gluteal, hip girdle, paraspinal, and other muscles work in concert to provide spinal stability. Core stability and its motor control have been shown to be imperative for initiation of functional limb movements, as needed in athletics. Sports medicine practitioners use core strengthening techniques to improve performance and prevent injury. Core strengthening, often called lumbar stabilization, also has been used as a therapeutic exercise treatment regimen for low back pain conditions. This article summarizes the anatomy of the core, the progression of core strengthening, the available evidence for its theoretical construct, and its efficacy in musculoskeletal conditions.

  19. HYDRATE CORE DRILLING TESTS

    Energy Technology Data Exchange (ETDEWEB)

    John H. Cohen; Thomas E. Williams; Ali G. Kadaster; Bill V. Liddell

    2002-11-01

    The ''Methane Hydrate Production from Alaskan Permafrost'' project is a three-year endeavor being conducted by Maurer Technology Inc. (MTI), Noble, and Anadarko Petroleum, in partnership with the U.S. DOE National Energy Technology Laboratory (NETL). The project's goal is to build on previous and ongoing R&D in the area of onshore hydrate deposition. The project team plans to design and implement a program to safely and economically drill, core and produce gas from arctic hydrates. The current work scope includes drilling and coring one well on Anadarko leases in FY 2003 during the winter drilling season. A specially built on-site core analysis laboratory will be used to determine some of the physical characteristics of the hydrates and surrounding rock. Prior to going to the field, the project team designed and conducted a controlled series of coring tests for simulating coring of hydrate formations. A variety of equipment and procedures were tested and modified to develop a practical solution for this special application. This Topical Report summarizes these coring tests. A special facility was designed and installed at MTI's Drilling Research Center (DRC) in Houston and used to conduct coring tests. Equipment and procedures were tested by cutting cores from frozen mixtures of sand and water supported by casing and designed to simulate hydrate formations. Tests were conducted with chilled drilling fluids. Tests showed that frozen core can be washed out and reduced in size by the action of the drilling fluid. Washing of the core by the drilling fluid caused a reduction in core diameter, making core recovery very difficult (if not impossible). One successful solution was to drill the last 6 inches of core dry (without fluid circulation). These tests demonstrated that it will be difficult to capture core when drilling in permafrost or hydrates without implementing certain safeguards. Among the coring tests was a simulated hydrate

  20. [Live epikeratophakia and deep lamellar keratoplasty for I-III stage-specific surgical treatment of keratoconus].

    Science.gov (United States)

    Krumeich, J H; Daniel, J

    1997-08-01

    Perforating keratoplasty (PKP) for the treatment of keratoconus is a temporary procedure that sacrifices the healthy recipient endothelium. As an alternative to PKP we perform live-epikeratophakia (L-EPI) in keratoconus I-II and deep lamellar keratoplasty (DLKP) in keratoconus II-III. 20 patients with keratoconus were operated on either with L-EPI for keratoconus I-II (n = 10) or DLKP for keratoconus II-III (n = 10) respectively. In all cases, corneal tissue eligible for corneal transplantation was used. L-EPI: The corneal lenticule was prepared by means of the Barraquer-Krumeich-Swinger (BKS) set. The recipient cornea was trephined to a depth of 0.3 mm with the Guided-Trephine-System (GTS). The incision was extended manually (inner diameter 7.0 mm, outer diameter 9.0 mm). No keratectomy was performed. The lenticule was fixed with a 10 x 0 nylon double-running anti-torque suture (DRA). DLKP: The recipient cornea was trephined with the 8.0 mm GTS to a depth of 0.68 mm. A lamellar removal of the upper layers was performed by hand. After mechanical removal of the graft endothelium, the remaining full thickness donor cornea was sutured into the bed with a 10 x 0 nylon DRA suture. L-EPI: Within this series, there was no disturbance of the healing process. Spherical equivalent and corneal astigmatism remained stable from the first month on. Visual acuity of 20/40 or better was obtained in 40% of the cases at 1 month, 53% at 6 months, and 100% at 1 year and 2 years. We did not observe any late decline of VA. Two patients with kerato-conus borderline stage II did not reach useful VA due to insufficiently reduced pre-existing irregular corneal astigmatism. These patients successfully underwent DLKP at 8 and 10 months respectively. DLKP: Except for 1 case (neurodermatitis), all lenticules remained stable with respect to refraction and radii up to the longest follow-up of 2 years. Starting from the first month on, refraction was stable. Visual acuity of 20/40 or better was

  1. Ceratoplastia endotelial lamelar profunda em distrofia de Fuchs: relato de caso Deep lamellar endothelial keratoplasty in Fuchs' dystrophy: case report

    Directory of Open Access Journals (Sweden)

    Fernando Trench de Oliveira Komatsu

    2004-08-01

    Full Text Available Descrever o caso de paciente portador de distrofia de Fuchs submetido a ceratoplastia endotelial lamelar profunda. O procedimento cirúrgico foi realizado no olho direito em um caso de distrofia de Fuchs com falência endotelial. Realizou-se incisão límbica superior, o estroma corneano foi delaminado e um disco lamelar de 8,5 mm com 0,150 mm de espessura, contendo estroma, membrana de Descemet e endotélio, foi transplantado sem sutura corneana. Foram avaliados: acuidade visual sem e com correção, biomicroscopia, topografia, paquimetria ultra-sônica e densidade endotelial. A paciente apresentava na avaliação pré-operatória acuidade visual com correção de 20/100 (+4,00 DE -3,25 DC x 60º, astigmatismo de 6,6 dioptrias (37,5 a 12º x 44,1 a 102º, espessura paquimétrica de 0,625 mm e contagem endotelial de 720 cel/mm². Após três meses da cirurgia, apresentava-se com acuidade visual com correção de 20/30 (-1,25 DE -0,50 DC x 45º, astigmatismo regular de 1,0 dioptria (37,2 a 75º x 38,2 a 165º, espessura paquimétrica de 0,503 mm e contagem endotelial de 2447 cel/mm². Observaram-se como complicações: corte inadvertido da íris, má coaptação de bordas, dobras do disco doador e nébula na interface. Os resultados preliminares sugerem que a ceratoplastia endotelial lamelar posterior é uma alternativa para o tratamento cirúrgico da distrofia de Fuchs com falência endotelial. Seguimento mais prolongado e maior número de casos são necessários para melhor entendimento e caracterização desta técnica e de suas repercussões.To report a case of deep lamellar endothelial keratoplasty (DLEK technique applied to a patient with Fuchs' dystrophy. The surgical procedure was performed on the right eye for a case of Fuchs' dystrophy with endothelial failure. Through a 9 mm self-sealing scleral tunnel incision, a stromal pocket was dissected at 0.35 mm depth. A 8.5 mm lamellar donor disc with 0.150 mm thickness, containing posterior

  2. Sediment Core Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Provides instrumentation and expertise for physical and geoacoustic characterization of marine sediments.DESCRIPTION: The multisensor core logger measures...

  3. Adaptive core simulation

    Science.gov (United States)

    Abdel-Khalik, Hany Samy

    The work presented in this thesis is a continuation of a master's thesis research project conducted by the author to gain insight into the applicability of inverse methods to developing adaptive simulation capabilities for core physics problems. Use of adaptive simulation is intended to improve the fidelity and robustness of important core attributes predictions such as core power distribution, thermal margins and core reactivity. Adaptive simulation utilizes a selected set of past and current reactor measurements of reactor observables, i.e. in-core instrumentations readings, to adapt the simulation in a meaningful way. A meaningful adaption will result in high fidelity and robust adapted core simulators models. To perform adaption, we propose an inverse theory approach in which the multitudes of input data to core simulators, i.e. reactor physics and thermal-hydraulic data, are to be adjusted to improve agreement with measured observables while keeping core simulators models unadapted. At a first glance, devising such adaption for typical core simulators models would render the approach impractical. This follows, since core simulators are based on very demanding computational models, i.e. based on complex physics models with millions of input data and output observables. This would spawn not only several prohibitive challenges but also numerous disparaging concerns. The challenges include the computational burdens of the sensitivity-type calculations required to construct Jacobian operators for the core simulators models. Also, the computational burdens of the uncertainty-type calculations required to estimate the uncertainty information of core simulators input data presents a demanding challenge. The concerns however are mainly related to the reliability of the adjusted input data. We demonstrate that the power of our proposed approach is mainly driven by taking advantage of this unfavorable situation. Our contribution begins with the realization that to obtain

  4. Mesothelial lamellar bodies in norm and experimental conditions. Transmission and scanning electron microscopic observations on the peritoneum, pleura and pericardium.

    Science.gov (United States)

    Michailova, K N

    2004-07-01

    The ultrastructural characteristics of the mesothelial intracellular and extracellular lamellar bodies (LB) in norm, and especially in pathological conditions are still unknown. After routine fixation procedure, material from organs in the three serous cavities of Wistar rats, as control group were compared with animals following experimental hemothorax (EH) and experimental peritonitis (EP), using transmission and scanning electron microscopy (TEM, SEM). Different membrane-bound profiles, short strip-like structures and single LB characterize the control group. Five days after EH small groups of LB were observed. Single balloon-like profiles, numerous particles and larger groups of LB with wide varieties in size, form and membrane structure characterize the 8th day after EH. Thin and concentric membranes build single LB the 5th day of EP. Eight days after the same treatment, groups of LB, complex structures with several multilamellar centers, strip-like structures with rough granulo-filamentous material and uninterrupted covering over wide areas were observed. We conclude that constant components in the untreated rats are different membrane profiles, as initial lamellar formations and single typical LB with predominant intracellular position. The preferable sites for exocytosis of LB are the intercellular spaces. The present data demonstrate simultaneous findings of the two main groups of formations by using routine fixation in the control group and in the treated animals. The first represent LB as well as other round profiles, observed by TEM and particles, observed by SEM, which are widespread and probably have a basic role. The second ones are strip-like structures and its SEM-equivalents, i.e. uninterrupted covering. TEM-profiles and their SEM-images show significant organ differences and in some cases lack of correspondence between both electron microscopic techniques in the same treatment. Significant enlargement of the number of LB and the length of the

  5. Comparison of contrast sensitivity and visual acuity between deep anterior lamellar keratoplasty and penetrating keratoplasty in patients with keratoconus

    Directory of Open Access Journals (Sweden)

    Mehmet Orcun Akdemir

    2012-12-01

    Full Text Available AIM: To evaluate postoperative visual acuity and contrast sensitivity results following deep anterior lamellar keratoplasty (DALK and penetrating keratoplasty (PK in patients with keratoconus (KC. METHODS: All the patients’ records with KC who had PK or DALK surgery between May 2010 and May 2011 were retrospectively reviewed. Sixty patients who underwent successful corneal transplantation for KC: 30 eyes underwent DALK and 30 eyes underwent PK were included in this study. Preoperative and postoperative mean logarithm of the minimum angle of resolution (logMAR uncorrected visual acuity (UCVA, logMAR best spectacle-corrected visual acuity (BSCVA and intraocular pressure (IOP were evaluated. Contrast sensitivity tests (CS were done preoperative and 2 months after all sutures had removed. All surgeries were performed under regional anesthesia (retrobulbar anesthesia by 1 surgeon (B.K. who was experienced in penetrating and lamellar keratoplasty techniques.RESULTS: The mean age of the DALK group was 29.67±4.95 (range 18-40 years and the PK group was 28.7±3.53 (range 18-39 years. Preoperatively there was no significant difference in the logMAR UCVA, logMAR BSCVA and IOP between the DALK (1.281±0.56; 0.97±0.85; 12.07±2.12mmHg and PK (1.34±0.21; 0.98±0.21; 13±2.12mmHg groups. One-year after surgery there was no significant difference in the mean logMAR UCVA and IOP between the DALK (0.46±0.37; 11.73±2.1mmHg and PK (0.38±0.21; 12±2.12mmHg groups. The mean contrast sensitivity was evaluated by CC-100 Topcon LCD at 1.5, 2.52, 4.23, 7.10 and 11.91 cycles per degree (cs/deg spatial frequencies before and 2 months after the all sutures had removed. CONCLUSION: All patients with keratoconus in both DALK and PK groups performed good visual function postoperatively. The mean contrast sensitivity increased considerably at all spatial frequencies compared with preoperative levels in the DALK and PK groups. The mean post-operative evaluation of

  6. Improved osteoblasts growth on osteomimetic hydroxyapatite/BaTiO{sub 3} composites with aligned lamellar porous structure

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Beilei [Department of Stomatology, Third Xiangya Hospital, Central South University, Changsha, Hunan 410013 (China); Chen, Liangjian, E-mail: jian007040@sina.com [Department of Stomatology, Third Xiangya Hospital, Central South University, Changsha, Hunan 410013 (China); State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Shao, Chunsheng [Department of Stomatology, Third Xiangya Hospital, Central South University, Changsha, Hunan 410013 (China); Zhang, Fuqiang; Zhou, Kechao [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Cao, Jun [Department of Stomatology, Third Xiangya Hospital, Central South University, Changsha, Hunan 410013 (China); Zhang, Dou, E-mail: dzhang@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China)

    2016-04-01

    Osteoblasts growing into bone substitute is an important step of bone regeneration. This study prepared porous hydroxyapatite (HA)/BaTiO{sub 3} piezoelectric composites with porosity of 40%, 50% and 60% by ice-templating method. Effects of HA/BaTiO{sub 3} composites with different porosities, with and without polarizing treatment on adhesion, proliferation and differentiation of osteoblasts were investigated in vitro. Results revealed that cell densities of the porous groups were significantly higher than those of the dense group (p < 0.05), so did the alkaline phosphate (ALP) and bone gla protein (BGP) activities. Porosity of 50% group exhibited higher ALP activity and BGP activity than those of the 40% and 60% groups. Scanning electron microscopy (SEM) observations revealed that osteoblasts adhered and stretched better on porous HA/BaTiO{sub 3} than on the dense one, especially HA/BaTiO{sub 3} with porosity of 50% and 60%. However, there was no significant difference in the cell morphology, cell densities, ALP and BGP activities between the polarized group and the non-polarized group (p > 0.05). The absence of mechanical loading on the polarized samples may account for this. The results indicated that hierarchically porous HA/BaTiO{sub 3} played a favorable part in osteoblasts proliferation, differentiation and adhesion process and is a promising bone substitute material. - Graphical abstract: Aligned porous structure of HA/BaTiO{sub 3} piezoelectric composites prepared by ice-templating method was similar to the lamellar Haversian system in bone tissue. When co-cultured with human osteosarcoma cells (MG63), porous HA/BaTiO{sub 3} composites exhibited remarkable biological activity in promoting proliferation, differentiation and adhesion of MG63 cells. - Highlights: • The aligned porous structure of HA/BaTiO{sub 3} composite was similar to the lamellar Haversian system in bone tissue. • The piezoelectric d{sub 33} coefficient of HA/BaTiO{sub 3} with porosity

  7. Core physics experiment of 100% MOX core: MISTRAL

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, T.; Matsu-ura, H.; Ueji, M. [Nuclear Power Engineering Corp., Tokyo (Japan); Cathalau, S.; Cabrillat, J.C.; Chauvin, J.P.; Finck, P.J.; Fougeras, P.; Flamenbaum, G.

    1997-12-31

    An extensive experimental program, MISTRAL, was undertaken in the EOLE critical facility of CEA in order to measure the main core physics parameters of 100% MOX loaded cores of light water reactors. The experimental program comprises four core configurations with high moderator to fuel ratio, including three homogeneous cores and one PWR type mock-up core. This paper presents the experiment of the first homogeneous core of uranium fuel as a reference core of the MOX cores and a part of the experiment of the second core, a 100% MOX homogeneous core. (author)

  8. Can Psychiatric Rehabilitation Be Core to CORE?

    Science.gov (United States)

    Olney, Marjorie F.; Gill, Kenneth J.

    2016-01-01

    Purpose: In this article, we seek to determine whether psychiatric rehabilitation principles and practices have been more fully incorporated into the Council on Rehabilitation Education (CORE) standards, the extent to which they are covered in four rehabilitation counseling "foundations" textbooks, and how they are reflected in the…

  9. Self‐propagating Combustion Triggered Synthesis of  3D Lamellar Graphene/BaFe12O19 Composite and Its  Electromagnetic Wave Absorption Properties

    Directory of Open Access Journals (Sweden)

    Tingkai Zhao

    2017-03-01

    Full Text Available The synthesis of 3D lamellar graphene/BaFe12O19 composites was performed by oxidizing graphite and sequentially self‐propagating combustion triggered process. The 3D lamellar graphene structures were formed due to the synergistic effect of the tremendous heat induced gasification as well as huge volume expansion. The 3D lamellar graphene/BaFe12O19 composites bearing 30 wt % graphene present the reflection loss peak at −27.23 dB as well as the frequency bandwidth at 2.28 GHz (< −10 dB. The 3D lamellar graphene structures could consume the incident waves through multiple Reflection and scattering within the layered structures, Prolonging the propagation path of electromagnetic waves in the absorbers.

  10. Synthesis and structural characterization of ZnO-and CuO-NPs supported mesoporous silica materials (hexagonal SBA-15 and lamellar-SiO2)

    Science.gov (United States)

    El-Nahhal, Issa M.; Salem, Jamil K.; Tabasi, Nihal S.; Hempelmann, Rolf; Kodeh, Fawzi S.

    2018-01-01

    Two different mesoporous silica structures (hexagonal and lamellar) were synthesized via sol-gel method using a series of triblock copolymer (Pluronic) surfactants. L81, L61 & L31 surfactants form lamellar structure whereas P123 surfactant forms a hexagonal structure. CuO and ZnO nanoparticles (NPs) supported mesoporous silica were synthesized using impregnation method. The structural properties of these materials were investigated using several characterization techniques such as FTIR, XRD, SAXS, TEM and TGA. SAXS and TEM confirmed that the obtained mesoporous silica is based on the EO/PO ratio of Pluronic surfactants. They proved that the mesoporosity of silica is well maintained even after they loaded with metal oxide nanoparticles.

  11. New Development in Selective Laser Melting of Ti-6Al-4V: A Wider Processing Window for the Achievement of Fully Lamellar α + β Microstructures

    Science.gov (United States)

    Lui, E. W.; Xu, W.; Pateras, A.; Qian, M.; Brandt, M.

    2017-09-01

    Recent progress has shown that Ti-6Al-4V fabricated by selective laser melting (SLM) can achieve a fully lamellar α + β microstructure using 60 µm layer thickness in the as-built state via in situ martensite decomposition by manipulating the processing parameters. The potential to broaden the processing window was explored in this study by increasing the layer thickness to the less commonly used 90 µm. Fully lamellar α + β microstructures were produced in the as-built state using inter-layer times in the range of 1-12 s. Microstructural features such as the α-lath thickness and morphology were sensitive to both build height and inter-layer time. The α-laths produced using the inter-layer time of 1 s were much coarser than those produced with the inter-layer time of 12 s. The fine fully lamellar α + β structure resulted in tensile ductility of 11% and yield strength of 980 MPa. The tensile properties can be further improved by minimizing the presence of process-induced defects.

  12. Lateral Growth Limitation of Corneal Fibrils and Their Lamellar Stacking Depend on Covalent Collagen Cross-linking by Transglutaminase-2 and Lysyl Oxidases, Respectively*

    Science.gov (United States)

    Wang, Lei; Uhlig, Philipp C.; Eikenberry, Eric F.; Robenek, Horst; Bruckner, Peter; Hansen, Uwe

    2014-01-01

    Corneal stroma contains an extracellular matrix of orthogonal lamellae formed by parallel and equidistant fibrils with a homogeneous diameter of ∼35 nm. This is indispensable for corneal transparency and mechanical functions. However, the mechanisms controlling corneal fibrillogenesis are incompletely understood and the conditions required for lamellar stacking are essentially unknown. Under appropriate conditions, chick embryo corneal fibroblasts can produce an extracellular matrix in vitro resembling primary corneal stroma during embryonic development. Among other requirements, cross-links between fibrillar collagens, introduced by tissue transglutaminase-2, are necessary for the self-assembly of uniform, small diameter fibrils but not their lamellar stacking. By contrast, the subsequent lamellar organization into plywood-like stacks depends on lysyl aldehyde-derived cross-links introduced by lysyl oxidase activity, which, in turn, only weakly influences fibril diameters. These cross-links are introduced at early stages of fibrillogenesis. The enzymes are likely to be important for a correct matrix deposition also during repair of the cornea. PMID:24265319

  13. Lunar Core and Tides

    Science.gov (United States)

    Williams, J. G.; Boggs, D. H.; Ratcliff, J. T.

    2004-01-01

    Variations in rotation and orientation of the Moon are sensitive to solid-body tidal dissipation, dissipation due to relative motion at the fluid-core/solid-mantle boundary, and tidal Love number k2 [1,2]. There is weaker sensitivity to flattening of the core-mantle boundary (CMB) [2,3,4] and fluid core moment of inertia [1]. Accurate Lunar Laser Ranging (LLR) measurements of the distance from observatories on the Earth to four retroreflector arrays on the Moon are sensitive to lunar rotation and orientation variations and tidal displacements. Past solutions using the LLR data have given results for dissipation due to solid-body tides and fluid core [1] plus Love number [1-5]. Detection of CMB flattening, which in the past has been marginal but improving [3,4,5], now seems significant. Direct detection of the core moment has not yet been achieved.

  14. Evolution of entanglements during the response to a uniaxial deformation of lamellar triblock copolymers and polymer glasses.

    Science.gov (United States)

    Léonforte, F

    2010-10-01

    Using coarse-grained molecular-dynamics simulations, a generic styrene-block-butadiene-block-styrene triblock copolymer under lamellar conformation is used in order to investigate the mutual entanglement evolution when a structure of alternating glassy (S)/rubbery (B) layers is submitted to an imposed deformation. By varying the amount of loop chains between each phase, i.e., noncrossing chains, it is possible to generate different types of S/B interface definitions. A specific boundary driven tensile strain protocol has been developed in order to mimic "real" experiments and measure the stress-strain curve. The same protocol is also applied to a reference state consisting in a directed glassy homopolymers, as well as to an isotropic glassy polymer. The evolution of initial mutual entanglements from the undeformed samples during the whole deformation process is monitored. It is shown for all considered systems that initial entanglements mostly participate to the preyield regime of the stress-strain curve and that this network is debonded during the strain-hardening regime. For triblocks with a non-null amount of crossing chains, the lower the amount is, the longer the memory effect of the initial entanglement network in the postyield regime is. On the fly distributions of entanglements, which depart from the postyield regime, depict memory effects and long-time correlations during the strain-hardening regime. For triblocks, loop chains reinforce these effects.

  15. Synchrotron x-ray study of the modulated lamellar phase Pβ' in the lecithin-water system

    Science.gov (United States)

    Wack, Daniel C.; Webb, Watt W.

    1989-09-01

    The results of a high-resolution, synchrotron x-ray powder diffraction study of lattice constants in the Pβ' (``rippled'') phase of lecithin-water multilamellar mixtures are given. The variation with water volume fraction φw and hydrocarbon chain length Nc of the modulation wave vector Qr suggests that membrane curvature and hydration interactions between membranes play a significant role in the modulation. The dependence of the membrane thickness and area per head group on Nc indicates that the conformation of hydrocarbon chains is predominantly solidlike. The appearance of significant intensity in higher harmonics of the modulation wave vector rules out simple (e.g., sinusoidal or triangular) membrane density modulations. The results are consistent with a Lifshitz phenomenological model for lamellar phases of interacting membranes proposed by Goldstein and Liebler [Phys. Rev. Lett. 61, 2213 (1988)]. The phase behavior predicted by the model includes a multicritical point called the Lifshitz point where the wavelength of the modulation diverges. The experimental results indicate that this multicritical point lies in the vicinity of Nc=9 and φw=0.18.

  16. The Synthesis and Processing of Self-Healing Materials: A Lamellar Shape Memory Alloy in Composite Structure

    Science.gov (United States)

    Rabeeh, Bakr Mohamed; Fouad, Yasser

    Nontraditional self-healing alloy composite has been introduced to address the need for self-repairable high-strength structural materials. Cu-Zn/Al laminates are uniaxial hot pressed for either lamellar or particulate composite. A new bridging and stitching technique is introduced with crack mitigation via the synergetic effect of interfacial alloying elements. Low melting phase (LMP) induced structures of Al phase, Cr-Fe phase, and Al-Cu-Zn phase via alloy segregation. Microstructural and mechanical characterization is also established via scanning electron microscopy, energy dispersive x-ray spectroscopy and tensile testing. The interphase kinetic established with micro plasticity, metal flow, low melting phase, LMP and delocalized Al enriched zone and Cu enriched zone. The improvements in performance of self-healing interphase with SMA composite structure are due to heating of low melting phase induce crack closure, and crack mitigation via stitching and bridging mechanisms. Engineering material can be designed with multifunctionalities ranging from the macro- to Nano-scale to optimize performance while minimizing time and the need for extensive repair.

  17. Deep anterior lamellar keratoplasty using irradiated acellular cornea with amniotic membrane transplantation for intractable ocular surface diseases.

    Science.gov (United States)

    Wee, Sung Wook; Choi, Sang Uk; Kim, Jae Chan

    2015-04-01

    To report the clinical outcomes of deep anterior lamellar keratoplasty (DALK) when sterile gamma-irradiated acellular corneal tissues (VisionGraft) are used in combination with amniotic membrane transplantation (AMT) for intractable ocular surface diseases. The medical records of fifteen patients who had DALK with AMT were retrospectively reviewed. Indications for surgery included ocular burn, bacterial keratitis, herpes simplex virus keratitis, corneal opacity with Stevens-Johnson syndrome, Mooren's ulcer, idiopathic myxoid degeneration of corneal stroma, and recurrent band keratopathy. DALK was performed using partial-thickness acellular corneal tissue and a temporary amniotic membrane patch was added at the end of the operation. All cases that underwent DALK with AMT became epithelialized within 2 postoperative weeks. Twelve patients showed favorable outcomes without graft rejection, corneal opacification, or neovascularization. The other three grafts developed corneal opacification and neovascularization, and required additional penetrating keratoplasty (PK). Unlike the results of previous PKs, there were no graft rejections and the graft clarity was well-maintained in these three cases for at least 8 months after PK. DALK using sterile acellular corneal tissues in combination with AMT may be a good therapeutic strategy for treating intractable ocular surface diseases because of lowered immune rejection, fibroblast activation, and facilitation of epithelialization. Furthermore, DALK can help stabilize the ocular surface, prolong graft survival, and may allow better outcomes when combined with subsequent PK.

  18. In Vivo Confocal Microscopic Observation of Lamellar Corneal Transplantation in the Rabbit Using Xenogenic Acellular Corneal Scaffolds as a Substitute

    Science.gov (United States)

    Feng, Yun; Wang, Wei

    2015-01-01

    Background: The limiting factor to corneal transplantation is the availability of donors. Research has suggested that xenogenic acellular corneal scaffolds (XACS) may be a possible alternative to transplantation. This study aimed to investigate the viability of performing lamellar corneal transplantation (LCT) in rabbits using canine XACS. Methods: Fresh dog corneas were decellularized by serial digestion, and LCT was performed on rabbit eyes using xenogeneic decellularized corneal matrix. Cellular and morphological changes were observed by slit-lamp, light, and scanning electron microscopy at 7, 30 and 90 days postoperatively. Immunocytochemical staining for specific markers such as keratin 3, vimentin and MUC5AC, was used to identify cells in the graft. Results: Decellularized xenogenic corneal matrix remained transparent for about 1-month after LCT. The recipient cells were able to survive and proliferate into the grafts. Three months after transplantation, grafts had merged with host tissue, and graft epithelialization and vascularization had occurred. Corneal nerve fibers were able to grow into the graft in rabbits transplanted with XACS. Conclusions: Xenogenic acellular corneal scaffolds can maintain the transparency of corneal grafts about 1-month and permit growth of cells and nerve fibers, and is, therefore, a potential substitute or carrier for a replacement cornea. PMID:25836615

  19. The influence of lamellar orientation on corneal material behavior: biomechanical and structural changes in an avian corneal disorder.

    Science.gov (United States)

    Boote, Craig; Elsheikh, Ahmed; Kassem, Wael; Kamma-Lorger, Christina S; Hocking, Paul M; White, Nick; Inglehearn, Chris F; Ali, Manir; Meek, Keith M

    2011-03-01

    Retinopathy, globe enlarged (RGE) is an inherited genetic disease of chickens with a corneal phenotype characterized by loss of tissue curvature and changes in peripheral collagen fibril alignment. This study aimed to characterize the material behavior of normal and RGE chicken corneas under inflation and compare this with new spatial- and depth-resolved microstructural information to investigate how stromal fibril architecture determines corneal behavior under intraocular pressure (IOP). Six RGE chicken corneas and six age-matched normal controls were tested using trephinate inflation and their stress-strain behavior determined as a function of posterior pressure. Second harmonic generation mulitphoton microscopy was used to compare the in-plane appearance and degree of through-plane interlacing of collagen lamellae between normal and mutant corneas. RGE corneas displayed a 30-130% increase in material stiffness [E(tangent)(RGE) = 0.94 ± 0.18 MPa to 3.09 ± 0.66 MPa; E(tangent)(normals) = 0.72 ± 0.13 MPa to 1.34 ± 0.35 MPa] (P ≤ 0.05). The normal in-plane disposition of anterior collagen in the peripheral cornea was altered in RGE but through-plane lamellar interlacing was unaffected. This article demonstrates changes in corneal material behavior in RGE that are qualitatively consistent with microstructural collagen alterations identified both herein and previously. This study indicates that, in general, changes in stromal fibril orientation may significantly affect corneal material behavior and thereby its response to IOP.

  20. Clinical application of TICL implantation for ametropia following deep anterior lamellar keratoplasty for keratoconus: A CONSORT-compliant article.

    Science.gov (United States)

    Qin, Qin; Yang, Liping; He, Zifang; Huang, Zhenping

    2017-02-01

    This study aimed to investigate the clinical application of phakic toric intraocular collamer lens (TICL) implantation in treating ametropia following deep anterior lamellar keratoplasty (DALK) for patients with keratoconus, especially the effectiveness and safety of high astigmatism and indications of TICL implantation after corneal transplantation. Using the self-controlled case series observation approach, 9 patients with ametropia (9 eyes) who underwent DALK surgery for keratoconus 1.5 years ago with stitches removed 3 months ago were kept under observation from May 2013 to April 2014 in Ophthalmic Center of Nanjing Drum Tower Hospital affiliated to Nanjing Medical University. TICL implantation was performed in all patients. The uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA) were examined before surgery and 1 week, 6 months, 1 year, and 2 years after surgery. Corneal astigmatism, corneal thickness, anterior chamber depth, corneal endothelial cell density (ECD), and preoperative and postoperative intraocular pressures at different time points were measured. Intraoperative or postoperative complications of TICL implantation were observed, and the safety of the operation was evaluated. The UCVA and BCVA in all operated eyes were better 6 months after surgery than before surgery. The spherical diopter and cylindrical diopter decreased to different degrees after surgery. Six months after surgery, the deviation of TICL axis in all operated eyes was less than 10 degrees, tending to be stable. No severe intraoperative or postoperative complication occurred. TICL implantation was an optional choice for ametropia correction after DALK surgery, especially in patients with high astigmatism.

  1. Triple chamber: a clinical rarity after deep anterior lamellar keratoplasty and role of optical coherence tomography in management.

    Science.gov (United States)

    Selvan, Harathy; Patil, Mukesh; Yadav, Shikha; Tandon, Radhika

    2017-10-30

    To report a case demonstrating triple chamber following deep anterior lamellar keratoplasty (DALK) and its successful intra-operative optical coherence tomography-guided management. Case report of a young male with macular corneal dystrophy, who underwent DALK in his left eye by Big-Bubble technique. The surgery was uneventful. On the first post-operative day, triple chamber was observed and followed-up with serial clinical photography and anterior segment optical coherence tomography. Due to decrease in graft clarity and increase in volume of the two extra chambers, interface drainage along with descemetopexy was undertaken 4 days later. The compartments constituting the triple chamber were those in-between the donor tissue and host pre-Descemet layer (Dua's layer), the latter and host Descemet membrane and the true anterior chamber. Presence of viscoelastic in the interface was identified as the cause. Microscope integrated optical coherence tomography (MiOCT) guided drainage followed by intracameral air tamponade ensured near total disappearance of the two extra chambers at the end of surgery. Examination on the next day confirmed complete apposition of the graft and host. To the best of our knowledge, this is a unique demonstration of Dua's layer in vivo by slit lamp biomicroscopy and description of MiOCT guided management of triple chamber.

  2. Deep anterior lamellar keratoplasty—triple procedure: a useful clinical application of the pre-Descemet's layer (Dua's layer)

    Science.gov (United States)

    Zaki, A A; Elalfy, M S; Said, D G; Dua, H S

    2015-01-01

    Purpose To describe a technique which exploits the transparency and toughness of the pre-Descemets layer (Dua's layer) to safely perform deep anterior lamellar keratoplasty (DALK) and phacoemulsification at the same time. Methods Three DALK procedures combined with phacoemulsification were performed by the same surgeon using the big-bubble (BB) technique at the Research Institute of Ophthalmology, Cairo, Egypt. In two cases a type-1 BB, baring Dua's layer, was achieved and in one case a type-2 BB, baring the Descemet's membrane (DM), was achieved. The surgeries were video recorded and photo slit-lamp images were taken in the follow-up visits. Results DALK with phacoemulsification and lens implant was carried out in both patients where a type-1 BB was achieved. At a follow up of 18 months (first case) and 6 months (second case), the best corrected vision was 6/12 for each. In the case where a type-2 BB was achieved, the DM ruptured during injection of viscoelastic prior to capsulorhexis. The procedure was converted to a penetrating keratoplasty without phacoemulsification. Conclusion When a type-1 BB is achieved simultaneous DALK and phacoemulsification can be safely accomplished. Dua's layer allows a clear view for performing phacoemulsification with the added benefit of its toughness, which can maintain a stable anterior chamber for cataract surgery. This should not be attempted when a type-2 BB is achieved. PMID:25359285

  3. Deep anterior lamellar keratoplasty--triple procedure: a useful clinical application of the pre-Descemet's layer (Dua's layer).

    Science.gov (United States)

    Zaki, A A; Elalfy, M S; Said, D G; Dua, H S

    2015-03-01

    To describe a technique which exploits the transparency and toughness of the pre-Descemets layer (Dua's layer) to safely perform deep anterior lamellar keratoplasty (DALK) and phacoemulsification at the same time. Three DALK procedures combined with phacoemulsification were performed by the same surgeon using the big-bubble (BB) technique at the Research Institute of Ophthalmology, Cairo, Egypt. In two cases a type-1 BB, baring Dua's layer, was achieved and in one case a type-2 BB, baring the Descemet's membrane (DM), was achieved. The surgeries were video recorded and photo slit-lamp images were taken in the follow-up visits. DALK with phacoemulsification and lens implant was carried out in both patients where a type-1 BB was achieved. At a follow up of 18 months (first case) and 6 months (second case), the best corrected vision was 6/12 for each. In the case where a type-2 BB was achieved, the DM ruptured during injection of viscoelastic prior to capsulorhexis. The procedure was converted to a penetrating keratoplasty without phacoemulsification. When a type-1 BB is achieved simultaneous DALK and phacoemulsification can be safely accomplished. Dua's layer allows a clear view for performing phacoemulsification with the added benefit of its toughness, which can maintain a stable anterior chamber for cataract surgery. This should not be attempted when a type-2 BB is achieved.

  4. Wet-Peeling Technique of Deep Anterior Lamellar Keratoplasty With Hypotonic Water and Blunt Dissection for Healed Hydrops.

    Science.gov (United States)

    Zhao, Zelin; Li, Jinyang; Zheng, Qinxiang; Lin, Wei; Jhanji, Vishal; Chen, Wei

    2017-03-01

    To describe the surgical technique and outcomes of "wet-peeling" deep anterior lamellar keratoplasty (DALK) using sterile water and blunt dissection in cases with corneal scarring after healed corneal hydrops. Manual DALK using a "wet-peeling" technique was performed in 20 eyes of 20 consecutive patients with healed corneal hydrops between June 2011 and October 2013. Intraoperative microperforations were encountered in 2 (10%) cases. None of the cases required conversion to penetrating keratoplasty. There was significant improvement in mean best-corrected visual acuity at the end of 24 months postoperatively (0.99 ± 0.30 logMAR vs. 0.20 ± 0.11 logMAR; P < 0.001). The postoperative mean residual stromal bed thickness was 48.9 ± 5.9 μm, and mean central corneal thickness was 557.2 ± 50.3 μm. The mean endothelial density was 2021 ± 236 cells/mm at the final follow-up. Manual DALK using sterile water can be successfully performed in corneas with healed hydrops. Favorable visual outcomes may be attributed to thin residual bed thickness postoperatively.

  5. Emission spectroscopy of a ruthenium(ii) polypyridyl complex adsorbed on calcium niobate lamellar solids and nanosheets.

    Science.gov (United States)

    Maeda, Kazuhiko; Oshima, Takayoshi; Ishitani, Osamu

    2015-07-21

    Ru(ii) tris-diimine complexes are known to exhibit emission at around 630 nm as a result of (1)MLCT photoexcitation. The emission is quenched in the presence of a suitable semiconductor solid due to electron injection from the excited state of a Ru(ii) complex to the conduction band of the adjacent semiconductor. Here we investigated emission quenching behaviour of Ru(II){(4,4'-(CH3)2-bpy)2(4,4'-(CH2PO3H2)2-bpy)} (bpy = 2,2'-bipryridine) adsorbed on HCa2Nb3O10 solids having an ordered lamellar structure or a disordered nanostructure. Even though electron injection from the excited state of the Ru complex to the conduction band of nanostructured HCa2Nb3O10 is thermodynamically less favorable than that of layered HCa2Nb3O10, faster electron injection was observed using nanostructured HCa2Nb3O10. Experimental results highlighted that electron injection from the excited Ru complex takes place not only in the conduction band of HCa2Nb3O10 but also mid-gap states whose density is strongly dependent on both the morphological feature and the preparation method of HCa2Nb3O10.

  6. Visual outcomes after deep anterior lamellar keratoplasty using donor corneas without removal of Descemet membrane and endothelium

    Directory of Open Access Journals (Sweden)

    Tatiana Moura Bastos Prazeres

    Full Text Available ABSTRACT Purpose: The optical quality of the interface after deep anterior lamellar keratoplasty (DALK using the big-bubble technique has been shown to be excellent, leading to results comparable to penetrating keratoplasty. However, there is little in the literature with respect to the controversy surrounding the preparation of the donor cornea. The purpose of this study was to evaluate visual acuity (VA in patients with keratoconus who underwent DALK without removal of the donor graft endothelium. Methods: The records of 90 patients who underwent DALK without the removal of the Descemet membrane (DM and endothelium were retrospectively reviewed. Data collected included uncorrected VA (UCVA and spectacle-corrected VA (SCVA at 7, 30, 180 days, and 1 year postoperatively. Contact lens-corrected visual acuity (CLVA was evaluated after 1 year of the procedure. Results: UCVA was significantly better than preoperative values at 7 days (p<0.001, 30 days (p<0.001, 180 days (p<0.001, and 1 year (p<0.001 after surgery. The 1-year postoperative mean SCVA and CLVA also improved when compared with preoperative SCVA (p<0.001 for both. Conclusions: DALK utilizing donor corneas with attached Descemet membrane and endothelium results in satisfactory VA in patients with keratoconus.

  7. The t-core of an s-core

    OpenAIRE

    Fayers, Matthew

    2011-01-01

    We consider the $t$-core of an $s$-core partition, when $s$ and $t$ are coprime positive integers. Olsson has shown that the $t$-core of an $s$-core is again an $s$-core, and we examine certain actions of the affine symmetric group on $s$-cores which preserve the $t$-core of an $s$-core. Along the way, we give a new proof of Olsson's result. We also give a new proof of a result of Vandehey, showing that there is a simultaneous $s$- and $t$-core which contains all others.

  8. Dependence of Core and Extended Flux on Core Dominance ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Based on two extragalactic radio source samples, the core dominance parameter is calculated, and the correlations between the core/extended flux density and core dominance parameter are investigated. When the core dominance parameter is lower than unity, it is linearly correlated with the core flux ...

  9. Earth's inner core: Innermost inner core or hemispherical variations?

    NARCIS (Netherlands)

    Lythgoe, K. H.; Deuss, A.; Rudge, J. F.; Neufeld, J. A.

    2014-01-01

    The structure of Earth's deep inner core has important implications for core evolution, since it is thought to be related to the early stages of core formation. Previous studies have suggested that there exists an innermost inner core with distinct anisotropy relative to the rest of the inner core.

  10. Dependence of Core and Extended Flux on Core Dominance ...

    Indian Academy of Sciences (India)

    Abstract. Based on two extragalactic radio source samples, the core dominance parameter is calculated, and the correlations between the core/extended flux density and core dominance parameter are investi- gated. When the core dominance parameter is lower than unity, it is linearly correlated with the core flux density, ...

  11. Korrelasjon mellom core styrke, core stabilitet og utholdende styrke i core

    OpenAIRE

    Berg-Olsen, Andrea Marie; Fugelsøy, Eivor; Maurstad, Ann-Louise

    2010-01-01

    Formålet med studien var å se hvilke korrelasjon det er mellom core styrke, core stabilitet og utholdende styrke i core. Testingen bestod av tre hoveddeler hvor vi testet core styrke, core stabilitet og utholdende styrke i core. Innenfor core styrke og utholdende styrke i core ble tre ulike tester utført. Ved måling av core stabilitet ble det gjennomført kun en test. I core styrke ble isometrisk abdominal fleksjon, isometrisk rygg ekstensjon og isometrisk lateral fleksjon testet. Sit-ups p...

  12. Novel insights into the origin and diversification of photosynthesis based on analyses of conserved indels in the core reaction center proteins.

    Science.gov (United States)

    Khadka, Bijendra; Adeolu, Mobolaji; Blankenship, Robert E; Gupta, Radhey S

    2017-02-01

    The evolution and diversification of different types of photosynthetic reaction centers (RCs) remains an important unresolved problem. We report here novel sequence features of the core proteins from Type I RCs (RC-I) and Type II RCs (RC-II) whose analyses provide important insights into the evolution of the RCs. The sequence alignments of the RC-I core proteins contain two conserved inserts or deletions (indels), a 3 amino acid (aa) indel that is uniquely found in all RC-I homologs from Cyanobacteria (both PsaA and PsaB) and a 1 aa indel that is specifically shared by the Chlorobi and Acidobacteria homologs. Ancestral sequence reconstruction provides evidence that the RC-I core protein from Heliobacteriaceae (PshA), lacking these indels, is most closely related to the ancestral RC-I protein. Thus, the identified 3 aa and 1 aa indels in the RC-I protein sequences must have been deletions, which occurred, respectively, in an ancestor of the modern Cyanobacteria containing a homodimeric form of RC-I and in a common ancestor of the RC-I core protein from Chlorobi and Acidobacteria. We also report a conserved 1 aa indel in the RC-II protein sequences that is commonly shared by all homologs from Cyanobacteria but not found in the homologs from Chloroflexi, Proteobacteria and Gemmatimonadetes. Ancestral sequence reconstruction provides evidence that the RC-II subunits lacking this indel are more similar to the ancestral RC-II protein. The results of flexible structural alignments of the indel-containing region of the RC-II protein with the homologous region in the RC-I core protein, which shares structural similarity with the RC-II homologs, support the view that the 1 aa indel present in the RC-II homologs from Cyanobacteria is a deletion, which was not present in the ancestral form of the RC-II protein. Our analyses of the conserved indels found in the RC-I and RC-II proteins, thus, support the view that the earliest photosynthetic lineages with living descendants

  13. Core stability and bicycling.

    Science.gov (United States)

    Asplund, Chad; Ross, Michael

    2010-01-01

    Bicycling is a popular fitness activity in the United States and around the world. Because of the nature of the bicycling position, the neck and back are at risk for injury. One method to prevent these injuries is to ensure that the body's "core" is strong and stable. A strong and stable core also provides a platform to maximize power transfer, improving performance. Core exercises also may enhance recovery from intense bicycling efforts. Simple stability exercises can improve performance and may prevent injuries in bicyclists.

  14. IGCSE core mathematics

    CERN Document Server

    Wall, Terry

    2013-01-01

    Give your core level students the support and framework they require to get their best grades with this book dedicated to the core level content of the revised syllabus and written specifically to ensure a more appropriate pace. This title has been written for Core content of the revised Cambridge IGCSE Mathematics (0580) syllabus for first teaching from 2013. ? Gives students the practice they require to deepen their understanding through plenty of practice questions. ? Consolidates learning with unique digital resources on the CD, included free with every book. We are working with Cambridge

  15. Core shroud corner joints

    Science.gov (United States)

    Gilmore, Charles B.; Forsyth, David R.

    2013-09-10

    A core shroud is provided, which includes a number of planar members, a number of unitary corners, and a number of subassemblies each comprising a combination of the planar members and the unitary corners. Each unitary corner comprises a unitary extrusion including a first planar portion and a second planar portion disposed perpendicularly with respect to the first planar portion. At least one of the subassemblies comprises a plurality of the unitary corners disposed side-by-side in an alternating opposing relationship. A plurality of the subassemblies can be combined to form a quarter perimeter segment of the core shroud. Four quarter perimeter segments join together to form the core shroud.

  16. INTEGRAL core programme

    Science.gov (United States)

    Gehrels, N.; Schoenfelder, V.; Ubertini, P.; Winkler, C.

    1997-01-01

    The International Gamma Ray Astrophysics Laboratory (INTEGRAL) mission is described with emphasis on the INTEGRAL core program. The progress made in the planning activities for the core program is reported on. The INTEGRAL mission has a nominal lifetime of two years with a five year extension option. The observing time will be divided between the core program (between 30 and 35 percent during the first two years) and general observations. The core program consists of three main elements: the deep survey of the Galactic plane in the central radian of the Galaxy; frequent scans of the Galactic plane in the search for transient sources, and pointed observations of several selected sources. The allocation of the observation time is detailed and the sensitivities of the observations are outlined.

  17. The core helium flash

    Science.gov (United States)

    Cole, P. W.; Deupree, R. G.

    1980-12-01

    The role of convection in the core helium flash is simulated by two-dimensional eddies interacting with the thermonuclear runaway. These eddies are followed by the explicit solution of the two-dimensional conservation laws with a two-dimensional finite difference hydrodynamics code. Thus, no phenomenological theory of convection such as the local mixing length theory is required. The core helium flash is violent, producing a deflagration wave. This differs from the detonation wave (and subsequent disruption of the entire star) produced in previous spherically symmetric violent core helium flashes as the second dimension provides a degree of relief which allows the expansion wave to decouple itself from the burning front. The results predict that a considerable amount of helium in the core will be burned before the horizontal branch is reached and that some envelope mass loss is likely.

  18. Organizing Core Tasks

    DEFF Research Database (Denmark)

    Boll, Karen

    Civil servants conduct the work which makes welfare states functions on an everyday bases: Police men police, school teachers teach, and tax inspectors inspect. Focus in this paper is on the core tasks of tax inspectors. The paper argues that their core task of securing the collection of revenue...... has remained much the same within the last 10 years. However, how the core task has been organized has changed considerable under the influence of various “organizing devices”. The paper focusses on how organizing devices such as risk assessment, output-focus, effect orientation, and treatment...... projects influence the organization of core tasks within the tax administration. The paper shows that the organizational transformations based on the use of these devices have had consequences both for the overall collection of revenue and for the employees’ feeling of “making a difference”. All in all...

  19. Reference: -300CORE [PLACE

    Lifescience Database Archive (English)

    Full Text Available -300CORE Forde BG, Heyworth A, Pywell J, Kreis M Nucleotide sequence of a B1 hordein gene and the identifica...tion of possible upstream regulatory elements in endosperm storage protein genes fr

  20. iPSC Core

    Data.gov (United States)

    Federal Laboratory Consortium — The induced Pluripotent Stem Cells (iPSC) Core was created in 2011 to accelerate stem cell research in the NHLBI by providing investigators consultation, technical...

  1. The Core Knowledge System

    National Research Council Canada - National Science Library

    Strat, Thomas M; Smith, Grahame B

    1987-01-01

    This document contains an in-depth description of the Core Knowledge System (CKS)-an integrative environment for the many functions that must be performed by sensor-based autonomous and semi-autonomous systems...

  2. Double sequence core theorems

    Directory of Open Access Journals (Sweden)

    Richard F. Patterson

    1999-01-01

    Full Text Available In 1900, Pringsheim gave a definition of the convergence of double sequences. In this paper, that notion is extended by presenting definitions for the limit inferior and limit superior of double sequences. Also the core of a double sequence is defined. By using these definitions and the notion of regularity for 4-dimensional matrices, extensions, and variations of the Knopp Core theorem are proved.

  3. MCNP LWR Core Generator

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Noah A. [Los Alamos National Laboratory

    2012-08-14

    The reactor core input generator allows for MCNP input files to be tailored to design specifications and generated in seconds. Full reactor models can now easily be created by specifying a small set of parameters and generating an MCNP input for a full reactor core. Axial zoning of the core will allow for density variation in the fuel and moderator, with pin-by-pin fidelity, so that BWR cores can more accurately be modeled. LWR core work in progress: (1) Reflectivity option for specifying 1/4, 1/2, or full core simulation; (2) Axial zoning for moderator densities that vary with height; (3) Generating multiple types of assemblies for different fuel enrichments; and (4) Parameters for specifying BWR box walls. Fuel pin work in progress: (1) Radial and azimuthal zoning for generating further unique materials in fuel rods; (2) Options for specifying different types of fuel for MOX or multiple burn assemblies; (3) Additional options for replacing fuel rods with burnable poison rods; and (4) Control rod/blade modeling.

  4. Modified big-bubble technique compared to manual dissection deep anterior lamellar keratoplasty in the treatment of keratoconus.

    Science.gov (United States)

    Knutsson, Karl Anders; Rama, Paolo; Paganoni, Giorgio

    2015-08-01

    To evaluate the clinical findings and results of manual dissection deep anterior lamellar keratoplasty (DALK) compared to a modified big-bubble DALK technique in eyes affected by keratoconus. Sixty eyes of 60 patients with keratoconus were treated with one of the two surgical techniques manual DALK (n = 30); big-bubble DALK (n = 30). The main outcomes measured were visual acuity, corneal topographic parameters, thickness of residual stroma and endothelial cell density (ECD). Patients were examined postoperatively at 1 month, 6 months, 1 year and 1 month after suture removal. Final best spectacle-corrected visual acuity (BSCVA) measured 1 month after suture removal was 0.11 ± 0.08 LogMAR in the big-bubble group compared to 0.13 ± 0.08 in the manual DALK group (p = 0.227). In patients treated with the big-bubble technique without complications (Descemet's membrane completely bared), the stromal residue was not measureable. Mean stromal residual thickness in the manual DALK group was 30.50 ± 27.60 μm. Data analysis of the manual DALK group demonstrated a significant correlation between BSCVA and residual stromal thickness; lower residual stromal thickness correlated with better BSCVA values (Spearman ρ = 0.509, p = 0.018). Postoperative ECD was similar in both groups at all intervals, with no statistically significant differences. In both groups, ECD loss was only significant during the 1- to 6-month interval (p = 0.001 and p big-bubble DALK and manual DALK groups, respectively). Manual DALK provides comparable results to big-bubble DALK. Big-bubble DALK permits faster visual recovery and is a surgical technique, which can be easily converted to manual DALK in cases of unsuccessful 'big-bubble' formation. © 2015 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  5. Surfactant secretion in LRRK2 knock-out rats: changes in lamellar body morphology and rate of exocytosis.

    Directory of Open Access Journals (Sweden)

    Pika Miklavc

    Full Text Available Leucine-rich repeat kinase 2 (LRRK2 is known to play a role in the pathogenesis of various diseases including Parkinson disease, morbus Crohn, leprosy and cancer. LRRK2 is suggested to be involved in a number of cell biological processes such as vesicular trafficking, transcription, autophagy and lysosomal pathways. Recent histological studies of lungs of LRRK2 knock-out (LRRK2 -/- mice revealed significantly enlarged lamellar bodies (LBs in alveolar type II (ATII epithelial cells. LBs are large, lysosome-related storage organelles for pulmonary surfactant, which is released into the alveolar lumen upon LB exocytosis. In this study we used high-resolution, subcellular live-cell imaging assays to investigate whether similar morphological changes can be observed in primary ATII cells from LRRK2 -/- rats and whether such changes result in altered LB exocytosis. Similarly to the report in mice, ATII cells from LRRK2 -/- rats contained significantly enlarged LBs resulting in a >50% increase in LB volume. Stimulation of ATII cells with ATP elicited LB exocytosis in a significantly increased proportion of cells from LRRK2 -/- animals. LRRK2 -/- cells also displayed increased intracellular Ca(2+ release upon ATP treatment and significant triggering of LB exocytosis. These findings are in line with the strong Ca(2+-dependence of LB fusion activity and suggest that LRRK2 -/- affects exocytic response in ATII cells via modulating intracellular Ca(2+ signaling. Post-fusion regulation of surfactant secretion was unaltered. Actin coating of fused vesicles and subsequent vesicle compression to promote surfactant expulsion were comparable in cells from LRRK2 -/- and wt animals. Surprisingly, surfactant (phospholipid release from LRRK2 -/- cells was reduced following stimulation of LB exocytosis possibly due to impaired LB maturation and surfactant loading of LBs. In summary our results suggest that LRRK2 -/- affects LB size, modulates intracellular Ca(2

  6. Surfactant secretion in LRRK2 knock-out rats: changes in lamellar body morphology and rate of exocytosis.

    Science.gov (United States)

    Miklavc, Pika; Ehinger, Konstantin; Thompson, Kristin E; Hobi, Nina; Shimshek, Derya R; Frick, Manfred

    2014-01-01

    Leucine-rich repeat kinase 2 (LRRK2) is known to play a role in the pathogenesis of various diseases including Parkinson disease, morbus Crohn, leprosy and cancer. LRRK2 is suggested to be involved in a number of cell biological processes such as vesicular trafficking, transcription, autophagy and lysosomal pathways. Recent histological studies of lungs of LRRK2 knock-out (LRRK2 -/-) mice revealed significantly enlarged lamellar bodies (LBs) in alveolar type II (ATII) epithelial cells. LBs are large, lysosome-related storage organelles for pulmonary surfactant, which is released into the alveolar lumen upon LB exocytosis. In this study we used high-resolution, subcellular live-cell imaging assays to investigate whether similar morphological changes can be observed in primary ATII cells from LRRK2 -/- rats and whether such changes result in altered LB exocytosis. Similarly to the report in mice, ATII cells from LRRK2 -/- rats contained significantly enlarged LBs resulting in a >50% increase in LB volume. Stimulation of ATII cells with ATP elicited LB exocytosis in a significantly increased proportion of cells from LRRK2 -/- animals. LRRK2 -/- cells also displayed increased intracellular Ca(2+) release upon ATP treatment and significant triggering of LB exocytosis. These findings are in line with the strong Ca(2+)-dependence of LB fusion activity and suggest that LRRK2 -/- affects exocytic response in ATII cells via modulating intracellular Ca(2+) signaling. Post-fusion regulation of surfactant secretion was unaltered. Actin coating of fused vesicles and subsequent vesicle compression to promote surfactant expulsion were comparable in cells from LRRK2 -/- and wt animals. Surprisingly, surfactant (phospholipid) release from LRRK2 -/- cells was reduced following stimulation of LB exocytosis possibly due to impaired LB maturation and surfactant loading of LBs. In summary our results suggest that LRRK2 -/- affects LB size, modulates intracellular Ca(2+) signaling and

  7. Pachymetry-guided intrastromal air injection ("pachy-bubble") for deep anterior lamellar keratoplasty: results of the first 110 cases.

    Science.gov (United States)

    Ghanem, Ramon C; Bogoni, Ayla; Ghanem, Vinícius C

    2015-06-01

    To report intraoperative and 1-year postoperative results of the pachy-bubble technique for deep anterior lamellar keratoplasty (DALK). This prospective interventional case series included 110 eyes of 107 patients with anterior corneal pathology who underwent DALK, including 78 with keratoconus. Outcome measures included the rate of bubble formation, rate of completing DALK, bubble types, complications, and visual and keratometric parameters. Intrastromal air injection was attempted in 109 eyes, and the air bubble was achieved in 93 eyes (85.3%). Intrastromal 2% methylcellulose injection was attempted in 9 eyes, after unsuccessful air bubble formation, and the viscobubble was achieved in 7 eyes (77.8%). Manual layer-by-layer dissection was performed in 8 eyes. Bubble formation was reached in 100 eyes (90.9%). Overall, 105 eyes (95.5%) achieved DALK. Air bubble occurred as type 1 (white margin) in 96.6% of the cases and as type 2 (clear margin) in 3.4%. There was a statistically significant improvement in all visual and keratometric parameters analyzed. Macroperforations converted to penetrating keratoplasty occurred in 5 eyes (4.5%) and microperforations in 12 (10.9%). There were significantly higher rates of perforation when a bubble was not achieved (P = 0.018) and when it was achieved as type 2 (P = 0.033). Interface haze occurred in 5 eyes (4.5%) and stromal rejection in 11 (10.0%). A short learning curve was observed for air bubble formation. Bubble formation, especially type 1, is the key to decrease the risk of perforation in DALK. The pachy-bubble was safe, effective, and reproducible in promoting DALK with air bubble and viscobubble formation with a short learning curve.

  8. Corneal biomechanical properties and their correlates with healing process after Descemetic versus 
pre-Descemetic lamellar keratoplasty.

    Science.gov (United States)

    Abdelkader, Almamoun

    2013-03-23

    Purpose: To evaluate the influence of the wound-healing process on corneal biomechanics in patients after 2 types of deep anterior lamellar keratoplasty: Descemetic with total stromal resection vs pre-Descemetic with deep stromal dissection.
Methods: This prospective comparative study consisted of 32 eyes of 32 patients. Patients were divided into 2 groups: Descemetic (17 eyes) and pre-Descemetic (15 eyes). Reichert ocular response analyzer was used to measure corneal hysteresis (CH) and corneal resistance factor (CRF) at 1 and 3 months postoperatively. Central corneal thickness (CCT) was measured using ultrasonic pachymetry. In vivo confocal microscopy was also used to study the corneal wound-healing process and to correlate these events with the corneal biomechanics postoperatively in both groups.
Results: Both mean CH and mean CRF were significantly lower in the Descemetic than the pre-Descemetic group at 1 and 3 months postoperatively (p<0.0001). The reflectivity of activated keratocytes at both the interface and wound edge was less in the Descemetic than the pre-Descemetic group at all times as revealed by the confocal microscopy. No statistically significant difference in mean CCT was found between both groups at 1 and 3 months. Subsequent and progressive decrease in interface reflectivity of activated keratocytes was presented in both groups.
Conclusions: Healing process at the interface is key to optimal corneal integrity. In the pre-Descemetic group, stroma-to-stroma healing stimulated more activated keratocytes and hence stronger healing response, providing superior corneal biomechanics. Significant positive correlation between the intensity of the keratocyte activation and corneal integrity was found.

  9. Characterization of the lamellar rearrangement induced by cross-linking treatment in keratoconic corneal samples imaged by SHG microscopy

    Science.gov (United States)

    Mercatelli, R.; Ratto, F.; Tatini, F.; Rossi, F.; Menabuoni, L.; Nicoletti, R.; Pini, R.; Pavone, F. S.; Cicchi, R.

    2017-02-01

    Keratoconus is an eye disorder that features a reduced stiffness of the cornea and its consequent pathological deformation. Cross-Linking (CXL) treatment has proven useful in hindering the progression of keratoconus, offering a minimally-invasive alternative to corneal surgical transplantation. In this study, the biomechanical characteristics of a human keratoconic cornea were clinically examined in vivo soon before keratoplasty, and the morphological alterations of the collagen scaffold in the same cornea were examined ex vivo by means of Second-Harmonic Generation (SHG) microscopy. A healthy cornea and a CXL-treated keratoconus were compared. In particular, the lamellar organization in the three corneal samples was characterized in different stromal layers by detecting both forward- and backwardscattered SHG signal and then considering the forward/backward (F/B) ratio as parameter. The F/B ratio was used to characterize the morphological organization of collagen lamellae within different stromal layers, finding an increased disorder at the level of Bowman's membrane, opposed to a more regular organization within deeper stromal layers in all the examined samples. The organization of collagen lamellae in CXL-treated keratoconic samples was similar to that one found in healthy corneas, demonstrating that the CXL is able to rearrange the collagen scaffold and partially recover the properties of a healthy condition. The obtained results are in agreement with previous results obtained in studies aimed at monitoring the organization of fibrillar collagen using F/B SHG ratio. In conclusion, the proposed method might be useful for both diagnosing keratoconus as well as for monitoring the effects of the CXL treatment.

  10. The Influence of Lamellar Orientation on Corneal Material Behavior: Biomechanical and Structural Changes in an Avian Corneal Disorder

    Science.gov (United States)

    Elsheikh, Ahmed; Kassem, Wael; Kamma-Lorger, Christina S.; Hocking, Paul M.; White, Nick; Inglehearn, Chris F.; Ali, Manir; Meek, Keith M.

    2011-01-01

    Purpose. Retinopathy, globe enlarged (RGE) is an inherited genetic disease of chickens with a corneal phenotype characterized by loss of tissue curvature and changes in peripheral collagen fibril alignment. This study aimed to characterize the material behavior of normal and RGE chicken corneas under inflation and compare this with new spatial- and depth-resolved microstructural information to investigate how stromal fibril architecture determines corneal behavior under intraocular pressure (IOP). Methods. Six RGE chicken corneas and six age-matched normal controls were tested using trephinate inflation and their stress-strain behavior determined as a function of posterior pressure. Second harmonic generation mulitphoton microscopy was used to compare the in-plane appearance and degree of through-plane interlacing of collagen lamellae between normal and mutant corneas. Results. RGE corneas displayed a 30–130% increase in material stiffness [Etangent(RGE) = 0.94 ± 0.18 MPa to 3.09 ± 0.66 MPa; Etangent(normals) = 0.72 ± 0.13 MPa to 1.34 ± 0.35 MPa] (P ≤ 0.05). The normal in-plane disposition of anterior collagen in the peripheral cornea was altered in RGE but through-plane lamellar interlacing was unaffected. Conclusions. This article demonstrates changes in corneal material behavior in RGE that are qualitatively consistent with microstructural collagen alterations identified both herein and previously. This study indicates that, in general, changes in stromal fibril orientation may significantly affect corneal material behavior and thereby its response to IOP. PMID:21051696

  11. Comparison of Clinical Outcomes of Same-size Grafting between Deep Anterior Lamellar Keratoplasty and Penetrating Keratoplasty for Keratoconus

    Science.gov (United States)

    Oh, Baek Lok; Wee, Won Ryang

    2013-01-01

    Purpose To compare the clinical outcomes between deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PKP) with same-size grafts in patients with keratoconus. Methods Medical records of 16 eyes from 15 patients treated from June 2005 through April 2011 were retrospectively reviewed. Patients with contact lens intolerance or who were poor candidates for contact lens fitting due to advanced cone underwent keratoplasty. The transplantations consisted of 11 DALK and 5 PKP with same-size grafting for keratoconus. Best-corrected visual acuity (BCVA), refractive error, corneal topographic profiling, and clinical course were compared between DALK and PKP groups. Results The follow-up period was 30 ± 17 months in the DALK group and 45 ± 20 months in the PKP group (p = 0.145). At final follow-up, the DALK and PKP groups achieved a BCVA (logarithm of the minimum angle of resolution) of 0.34 and 0.52, respectively (p = 0.980). Postoperative refractive error and mean simulated keratometric index showed myopic astigmatism in both groups without any statistical difference. Corneal irregularity index measured at 5 mm in the DALK group was less than that of the PKP group at 1-year follow-up (p = 0.021); however, at final follow-up, there was no longer a statistically significant difference. Endothelial cell counts were lower in the PKP group than in the DALK group at final follow-up (p = 0.021). Conclusions The optical outcomes of DALK with same-size grafts for keratoconus are comparable to those of PKP. Endothelial cell counts are more stable in DALK compared to PKP. PMID:24082769

  12. Efficacy and Safety of Deep Anterior Lamellar Keratoplasty vs. Penetrating Keratoplasty for Keratoconus: A Meta-Analysis

    Science.gov (United States)

    Liu, Hao; Chen, Yihui; Wang, Peng; Li, Bing; Wang, Weifang; Su, Yan; Sheng, Minjie

    2015-01-01

    Purpose To evaluate difference in therapeutic outcomes between deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PKP) for the clinical treatment of keratoconus. Methods A comprehensive search was conducted in Pubmed, EMBASE, Cochrane Library, and Web of science. Eligible studies should include at least one of the following factors: best corrected visual acuity (BCVA), postoperative spherical equivalent (SE), postoperative astigmatism and endothelial cell count (ECC), central corneal thickness (CCT), graft rejection and graft failure, of which BCVA, graft rejection and graft failure were used as the primary outcome measures, and postoperative SE, astigmatism, CCT and ECC as the secondary outcome measures. Given the lack of randomized clinical trials (RCTs), cohort studies and prospective studies were considered eligible. Results Sixteen clinical trials involving 6625 eyes were included in this review, including 1185 eyes in DALK group, and 5440 eyes in PKP group. The outcomes were analyzed using Cochrane Review Manager (RevMan) version 5.0 software. The postoperative BCVA in DALK group was significantly better than that in PKP group (OR = 0.48; 95%CI 0.39 to 0.60; pastigmatism (p = 0.14) and CCT (p = 0.58) between DALK and PKP groups. And ECC in DALK group was significantly higher than PKP group (p<0.001). The postoperative complications, high intraocular pressure (high-IOP) and cataract were analyzed, fewer cases of complications occurred in DALK group than those in PKP group (high-IOP, OR 0.22, 95% CI 0.11–0.44, P<0.001) (cataract, OR 0.22; 95% CI 0.08–0.61, P = 0.004). And no cases of expulsive hemorrhage and endophthalmitis were reported. Conclusion The visual outcomes for DALK were not equivalent to PKP. The rate of graft failure was similar between DALK and PKP. Fewer postoperative complications occurred in DALK group, indicating that compared with PKP, DALK has lower efficacy but higher safety. PMID:25633311

  13. Clinical outcomes and risk factors for graft failure after deep anterior lamellar keratoplasty and penetrating keratoplasty for macular corneal dystrophy.

    Science.gov (United States)

    Reddy, Jagadesh C; Murthy, Somasheila I; Vaddavalli, Pravin K; Garg, Prashant; Ramappa, Muralidhar; Chaurasia, Sunita; Rathi, Varsha; Sangwan, Virender S

    2015-02-01

    The aim of this study was to compare visual acuity, clinical outcomes, complications, and risk factors for graft failure after deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) for macular corneal dystrophy. Retrospective comparative case series. The PK group consisted of 109 eyes of 84 patients and the DALK group consisted of 21 eyes of 20 patients. The mean logarithm of the minimum angle of resolution best-corrected visual acuity at 3 and 12 months was 0.5 versus 0.5 (P = 0.285) and 0.4 versus 0.4 (P = 0.67) in the DALK and PK groups, respectively. There was no significant statistical difference in astigmatism and spherical equivalent between the 2 groups at 12 months. In the PK group, graft rejection that was the most common cause of graft failure was seen in 27 eyes (25%), of which 55% occurred within 1 year. In the DALK group, Descemet membrane microperforation occurred in 5 eyes (24%) intraoperatively, and early postoperative Descemet membrane detachment with double anterior chamber occurred in 9 eyes (43%). Kaplan-Meier estimate of graft survival in PK versus DALK groups were 93% versus 80% at 1 year and 78% versus 70% at 4 years, respectively. Visual and refractive outcomes are comparable between DALK and PK groups. DALK was superior to PK in its safety against postoperative complications such as endothelial rejection and secondary glaucoma. Graft failure in DALK was mostly associated with either intraoperative or early postoperative complications. DALK is a viable surgical option in cases with macular corneal dystrophy.

  14. ENDOTHELIAL KERATOPLASTY: CLINICAL OUTCOMES IN THE TWO YEARS FOLLOWING DEEP LAMELLAR ENDOTHELIAL KERATOPLASTY (AN AMERICAN OPHTHALMOLOGICAL SOCIETY THESIS)

    Science.gov (United States)

    Terry, Mark A.

    2007-01-01

    Purpose To evaluate the clinical outcome of small-incision, deep lamellar endothelial keratoplasty (DLEK) for the treatment of endothelial dysfunction. Methods A prospective series of 79 eyes that underwent DLEK by a single surgeon was evaluated. Best spectacle-corrected visual acuity (BSCVA), refractive astigmatism, and central endothelial cell density (ECD) were measured preoperatively and at 6, 12, and 24 months. Results Data was available on 78 eyes (99%) at 6 months, 77 eyes (97%) at 1 year, and 79 eyes (100%) at 2 years. Mean BSCVA preoperatively of 20/71 improved to 20/42 by 6 months and remained stable. Eliminating eyes with known retinal disease, BSCVA of 20/40 or better was present in 60% (40 of 67) of eyes at 6 months, 74% (49 of 66) of eyes at 1 year, and 79% (53 of 68) of eyes at 2 years. Refractive astigmatism preoperatively was .91 ±.78 diopters and was unchanged by surgery over time with results at 6 months of 1.11 ±.76 (P = .052, power = .43), 1 year 1.04 ±.80 (P =.287, power = .06), and 2 years 1.10 ±.70 (P =.467, power = .22). The mean donor ECD preoperatively was 2819 ± 225 (2389 to 3385) cells/mm2, and this decreased by 26% at 6 months (2095 ± 380) (1097 to 2920) (P = .0001; 95% confidence interval [CI] = 643–809), 3% fewer at 1 year (2009 ± 393) (612 to 2723) (P = .054, power = .5), and 17% fewer at 2 years (1536 ± 547) (500 to 2546) (P astigmatic change, but progressive ECD decrease over time is of concern. PMID:18427629

  15. Partial lamellar keratoplasty for peripheral corneal disease using a graft from the glycerin-preserved corneoscleral rim.

    Science.gov (United States)

    Gao, Hua; Wang, Xiuxian; Echegaray, Jose J; Li, Suxia; Wang, Ting; Shi, Weiyun

    2014-06-01

    To evaluate the feasibility of partial lamellar keratoplasty (LK) for treatment of peripheral corneal disease (PCD) using a graft from the corneoscleral rim preserved in glycerin. Patients who underwent LK for PCD at Shandong Eye Hospital from January 2006 to December 2012 were included. Corneoscleral rims of donor grafts, out of which the corneal buttons had been punched and used for penetrating keratoplasty, were preserved in glycerin and used for LK procedures. A trephine of 7.5-8.0 mm was used to mark the central cornea. An excision was made according to the size of the lesions, after which a partial ring-shaped corneoscleral graft was transplanted to repair the peripheral cornea. Visual acuity, refractive astigmatism, and complications were monitored. There were 26 patients (28 eyes), including 15 patients with Terrien's marginal degeneration, eight with Mooren's ulcer, two with Wegener's granulomatosis, and one with peripheral corneal ulcer. The mean follow-up was 15 months (range, 6-36 months). Uncorrected visual acuity was improved by a mean of 3.17 Snellen chart lines (P = 0.010), and best spectacle-corrected visual acuity was improved by a mean of 0.85 Snellen chart lines (P = 0.045) at 6 months after surgery. The refractive astigmatism decreased by 5.1 ± 8.6 diopters (P = 0.003). Two patients suffering graft ulcers (recurrence) were successfully treated by a second partial LK. No graft rejection occurred. Partial LK using a graft from the corneoscleral rim appears to be effective in the treatment of patients with PCD. This approach saves the donor graft, which is important in the countries or regions with scarcity of donor tissue.

  16. Dynamics of big bubble formation in deep anterior lamellar keratoplasty by the big bubble technique: in vitro studies.

    Science.gov (United States)

    Dua, Harminder S; Faraj, Lana A; Kenawy, Mohamed B; AlTaan, Saief; Elalfy, Mohamed S; Katamish, Tarek; Said, Dalia G

    2017-05-08

    To examine the movement of air injected in the cornea in simulated deep anterior lamellar keratoplasty (DALK), from the needle tip to the formation of different types of big bubbles (BB) and to ascertain how air travels through the stroma and pre-Descemet's layer [Dua's layer (PDL)] to create a type-1 (air between PDL and deep stroma) and type-2BB (air between PDL and Descemet's membrane). Air was injected in 57 sclerocorneal discs and the passage recorded. Leaking points and sites of commencement of type-1 and type-2BB were examined by scanning electron microscopy. Stromal distribution of air pockets was studied by light microscopy. Uninjected corneas served as controls. Injected air followed a consistent pattern, initially as radial tracks to the limbus, then as circumferential bands along the limbus and finally centripetally to create predominantly a type-1BB. Type-2BB started at the periphery, by air emerging through clusters of tiny fenestrations discovered in the periphery of PDL. Fifteen to 20 such clusters were also seen in control samples on either side of the Descemet's attachment. Type-1BB was formed by air emerging through wide spaces between lamellae of deep stroma. Histologically, the circumferential band revealed an aggregation of air pockets in the mid-stroma. The consistent pattern of passage of air is indicative of the architecture and microanatomy of the corneal stroma where collagen lamellae are orthogonally arranged centrally and as a circular annulus at the periphery. The novel peripheral fenestrations explain the peripheral commencement of a type-2BB and the escape of air into the anterior chamber during DALK. © 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  17. Development of lamellar gel phase emulsion containing marigold oil (Calendula officinalis) as a potential modern wound dressing.

    Science.gov (United States)

    Okuma, C H; Andrade, T A M; Caetano, G F; Finci, L I; Maciel, N R; Topan, J F; Cefali, L C; Polizello, A C M; Carlo, T; Rogerio, A P; Spadaro, A C C; Isaac, V L B; Frade, M A C; Rocha-Filho, P A

    2015-04-25

    Appropriate therapeutics for wound treatments can be achieved by studying the pathophysiology of tissue repair. Here we develop formulations of lamellar gel phase (LGP) emulsions containing marigold (Calendula officinalis) oil, evaluating their stability and activity on experimental wound healing in rats. LGP emulsions were developed and evaluated based on a phase ternary diagram to select the best LGP emulsion, having a good amount of anisotropic structure and stability. The selected LGP formulation was analyzed according to the intrinsic and accelerated physical stability at different temperatures. In addition, in vitro and in vivo studies were carried out on wound healing rats as a model. The LGP emulsion (15.0% marigold oil; 10.0% of blend surfactants and 75.0% of purified water [w/w/w]) demonstrated good stability and high viscosity, suggesting longer contact of the formulation with the wound. No cytotoxic activity (50-1000 μg/mL) was observed in marigold oil. In the wound healing rat model, the LGP (15 mg/mL) showed an increase in the leukocyte recruitment to the wound at least on days 2 and 7, but reduced leukocyte recruitment after 14 and 21 days, as compared to the control. Additionally, collagen production was reduced in the LGP emulsion on days 2 and 7 and further accelerated the process of re-epithelialization of the wound itself. The methodology utilized in the present study has produced a potentially useful formulation for a stable LGP emulsion-containing marigold, which was able to improve the wound healing process. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Big bubble deep anterior lamellar keratoplasty: the collagen layer in the wall of the big bubble is unique.

    Science.gov (United States)

    Dua, Harminder S; Mastropasqua, Leonardo; Faraj, Lana; Nubile, Mario; Elalfy, Mohamed S; Lanzini, Manuela; Calienno, Roberta; Said, Dalia G

    2015-08-01

    In big bubble (BB), deep anterior lamellar keratoplasty intracorneal injection of air separates Descemet's membrane (DM) and the pre-Descemet's layer (Dua's layer [DL]) to create a type 1 BB. We tested the hypothesis that air injection after excision or ablation of DL will fail to produce a BB. Nine human sclero-corneal discs were used. Three served as controls. In three, a type 1 BB was created, the bubble wall was excised and more air injected in an attempt to create another BB. In three samples, the DM was removed and 22μ of posterior cornea were ablated by phototherapeutic keratectomy (PTK). Air was injected to induce formation of a BB. Tissue from these experiments was subjected to light and electron microscopy. In all three control eyes, a type 1 BB (DL + DM) was obtained. Air injection after excision of the type 1 BB wall in three samples failed to produce another BB. Following PTK of DL, injection of air failed to create a BB in all three samples. Multiple points of air leak from the deep stroma were observed in all six samples. Light and electron microscopy showed a clear distinction between the ablated and non-ablated areas of cornea. This study supports the hypothesis that a BB cannot be created once the DL is excised or ablated. This adds to evidence that DL is unique. It also demonstrates that DL is not a random separation of deep stroma of the cornea. © 2015 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  19. Mini-scleral lenses in the visual rehabilitation of patients after penetrating keratoplasty and deep lamellar anterior keratoplasty.

    Science.gov (United States)

    Alipour, Fateme; Behrouz, Mahmoud Jabarvand; Samet, Behnaz

    2015-02-01

    To evaluate fitting feasibility, efficacy, and safety of mini scleral contact lenses in correcting post corneal graft vision. Prospective interventional case series, 56 visually unsatisfied post corneal graft eyes of 45 patients were fitted with miniscleral lenses (15.8 mm). Keratometric values, UCVA and BSCVA, fit, best corrected vision with the lens, decision to order lens, comfortable daily wearing time (CDWT), contact lens handling issues, and contact lens related complications were documented. The mean age was 34.6 years (SD: 10.9), ranging from 8 to 63 years. Forty-three eyes had history of full thickness corneal graft, 12 eyes had deep anterior lamellar graft (DALK) and 1 eye had the rotational graft. The mean UCVA was 1.05 logMar (SD: 0.54), ranging from 0.30 to 2.52 logMar. The mean BSCVA was 0.73 logMar (SD: 0.50) ranging from 0.09 to 2.00 which improved to 0.17 logMar (SD: 0.19) with the miniscleral lens. All eyes had ideal (40 eyes) or acceptable (16 eyes) fits. Nineteen patients (23 eyes) ordered their lenses of whom 11 (14 eyes) continued using the lens with a mean follow up time of 21.92 months (SD: 6.8). These patients reported a mean CDWT of 9.62 h/day (SD: 4.5). Five eyes of 4 patients discontinued the lens. Four eyes were lost to follow-up. The main reported barriers for ordering the lenses were economic and handling concerns. Miniscleral contact lenses can be considered helpful in the visual management of post corneal graft patients. Other factors may influence the acceptance of the lenses. Copyright © 2014 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  20. Zero-charged catanionic lamellar liquid crystals doped with fullerene C60 for potential applications in tribology.

    Science.gov (United States)

    Chen, Mengjun; Liu, Baoyong; Wang, Xiaolin; Fu, Yanxu; Hao, Jingcheng; Li, Hongguang

    2017-09-20

    The formation of lamellar liquid crystals (LLCs) has been demonstrated in a few salt-free catanionic surfactant systems and their properties have been well documented. However, examples of their combination with other materials are relatively rare. Herein, a salt-free zero-charged catanionic surfactant with low chain melting temperature was prepared by mixing equimolar tetradecyltrimethylammonium oxide (TTAOH) and oleic acid (OA) in water, and its concentration-dependent aggregate transition was investigated. In the dilute region (cTTAO ≤ 5 wt%), fluorescence microscopy observations revealed the formation of vesicles (the Lαv phase). Further increasing cTTAO induced a transition from the Lαv phase to LLCs via a region where vesicles and lamellae coexist. With ordered hydrophobic domains, the LLCs can be used as hosts for the doping of fullerene C60 (refers to C60 hereafter) with the highest C60/TTAO weight ratio of 0.04. The doping of C60 effectively improves the viscoelasticity of the LLCs confirmed by rheological characterization while only slight modifications on their matrixes have been detected using small angle X-ray scattering measurements. The LLC/C60 hybrids with cTTAO = 80 wt% were then subjected to tribological measurements, and an obvious reduction in their friction coefficients and wear volumes was observed. The C60/TTAO weight ratio at which the best tribological performance appears was determined to be 0.01. Our results indicate that the combination of C60 and catanionic LLCs could lead to the appearance of a new generation of environmentally-benign lubricants.

  1. Comparison of Outcomes in Patients Who Underwent Deep Anterior Lamellar Keratoplasty and Those Converted to Penetrating Keratoplasty

    Directory of Open Access Journals (Sweden)

    Yusuf Koçluk

    2017-03-01

    Full Text Available Objectives: To compare clinical outcomes of cases who underwent deep anterior lamellar keratoplasty (DALK and cases who were converted to penetrating keratoplasty (PKP from DALK surgery. Materials and Methods: The records of 54 patients for whom DALK surgery was planned and were operated for different diagnoses between March 2013 and June 2015 were retrospectively analyzed. Patients were divided into two groups: group 1 (PKP group consisted of 23 cases who were converted to PKP due to Descemet’s membrane perforation at any stage of surgery; group 2 (DALK group consisted of 31 patients whose surgery could be completed as DALK. Preoperative and postoperative follow-up results were evaluated in each group. Results: Corrected distance visual acuity (CDVA increased in the postoperative period according to baseline in both groups. However, there was no statistically significant difference in the rates of CDVA increase between the groups (p=0.142. The mean astigmatism measured by corneal topography at final examination was 5.8±2.3 diopters in group 1 and 5.4±1.8 diopters in group 2. The difference between groups was not statistically significant (p=0.430. The groups were not statistically different regarding postoperative pachymetry (p=0.453. The grafts in all 54 patients (100% were clear at final postoperative examination. There were no statistically significant differences between the groups in terms of postoperative complications. Conclusion: Similar clinical outcomes were obtained in our study for patients who underwent DALK and those whose procedure was converted from DALK to PKP.

  2. Packing in protein cores

    Science.gov (United States)

    Gaines, J. C.; Clark, A. H.; Regan, L.; O'Hern, C. S.

    2017-07-01

    Proteins are biological polymers that underlie all cellular functions. The first high-resolution protein structures were determined by x-ray crystallography in the 1960s. Since then, there has been continued interest in understanding and predicting protein structure and stability. It is well-established that a large contribution to protein stability originates from the sequestration from solvent of hydrophobic residues in the protein core. How are such hydrophobic residues arranged in the core; how can one best model the packing of these residues, and are residues loosely packed with multiple allowed side chain conformations or densely packed with a single allowed side chain conformation? Here we show that to properly model the packing of residues in protein cores it is essential that amino acids are represented by appropriately calibrated atom sizes, and that hydrogen atoms are explicitly included. We show that protein cores possess a packing fraction of φ ≈ 0.56 , which is significantly less than the typically quoted value of 0.74 obtained using the extended atom representation. We also compare the results for the packing of amino acids in protein cores to results obtained for jammed packings from discrete element simulations of spheres, elongated particles, and composite particles with bumpy surfaces. We show that amino acids in protein cores pack as densely as disordered jammed packings of particles with similar values for the aspect ratio and bumpiness as found for amino acids. Knowing the structural properties of protein cores is of both fundamental and practical importance. Practically, it enables the assessment of changes in the structure and stability of proteins arising from amino acid mutations (such as those identified as a result of the massive human genome sequencing efforts) and the design of new folded, stable proteins and protein-protein interactions with tunable specificity and affinity.

  3. Bioinformatics Core Project Management

    Science.gov (United States)

    Vangala, Mahesh; Vincent, James; Driscoll, Heather

    2013-01-01

    Bioinformatics cores that provide fee for service style support encounter a wide variety of projects. The scope of projects varies greatly among investigators. Because of this variety, it is difficult to develop a set of predefined services that fit all project types. While our own core has developed a baseline set of services, we found in practice these often needed significant modification to meet the goals of particular investigator. To overcome this problem we factored common features of all projects and partitioned them into groups: workflow management, data management, user results, and tracking and reporting. We then implemented best practices for each group using commercial and open source software combined with our own management policies. Finally we linked these areas together to produce an overall integrated project management solution that combines workflow management, data management, user results management and reporting capabilities. This system solves the problem of developing well defined services that are trackable and repeatable while simultaneously enabling flexibility that is easily managed. The result improves the effectiveness and efficiency of the bioinformatics core for scientists working within the core, for investigators receiving core support and for external auditors and evaluators.

  4. Inner core structure behind the PKP core phase triplication

    NARCIS (Netherlands)

    Blom, Nienke A.; Deuss, Arwen; Paulssen, Hanneke; Waszek, Lauren

    The structure of the Earth's inner core is not well known between depths of ∼100–200 km beneath the inner core boundary. This is a result of the PKP core phase triplication and the existence of strong precursors to PKP phases, which hinder the measurement of inner core compressional PKIKP waves at

  5. Biaxial mechanics and inter-lamellar shearing of stem-cell seeded electrospun angle-ply laminates for annulus fibrosus tissue engineering.

    Science.gov (United States)

    Driscoll, Tristan P; Nakasone, Ryan H; Szczesny, Spencer E; Elliott, Dawn M; Mauck, Robert L

    2013-06-01

    The annulus fibrosus (AF) of the intervertebral disk plays a critical role in vertebral load transmission that is heavily dependent on the microscale structure and composition of the tissue. With degeneration, both structure and composition are compromised, resulting in a loss of AF mechanical function. Numerous tissue engineering strategies have addressed the issue of AF degeneration, but few have focused on recapitulation of AF microstructure and function. One approach that allows for generation of engineered AF with appropriate (+/-)30° lamellar microstructure is the use of aligned electrospun scaffolds seeded with mesenchymal stem cells (MSCs) and assembled into angle-ply laminates (APL). Previous work indicates that opposing lamellar orientation is necessary for development of near native uniaxial tensile properties. However, most native AF tensile loads are applied biaxially, as the disk is subjected to multi-axial loads and is constrained by its attachments to the vertebral bodies. Thus, the objective of this study was to evaluate the biaxial mechanical response of engineered AF bilayers, and to determine the importance of opposing lamellar structure under this loading regime. Opposing bilayers, which replicate native AF structure, showed a significantly higher modulus in both testing directions compared to parallel bilayers, and reached ∼60% of native AF biaxial properties. Associated with this increase in biaxial properties, significantly less shear, and significantly higher stretch in the fiber direction, was observed. These results provide additional insight into native tissue structure-function relationships, as well as new benchmarks for engineering functional AF tissue constructs. Copyright © 2013 Orthopaedic Research Society.

  6. A comparison study of rhodamine B photodegradation over nitrogen-doped lamellar niobic acid and titanic acid under visible-light irradiation.

    Science.gov (United States)

    Li, Xiukai; Kikugawa, Naoki; Ye, Jinhua

    2009-01-01

    A solid-state reaction method with urea as a nitrogen precursor was used to prepare nitrogen-doped lamellar niobic and titanic solid acids (i.e., HNb(3)O(8) and H(2)Ti(4)O(9)) with different acidities for visible-light photocatalysis. The photocatalytic activities of the nitrogen-doped solid acids were evaluated for rhodamine B (RhB) degradation and the results were compared with those obtained over the corresponding nitrogen-doped potassium salts. Techniques such as XRD, BET, SEM, X-ray photoelectron spectroscopy, and UV-visible diffuse reflectance spectroscopy were adopted to explore the nature of the materials as well as the characteristics of the doped nitrogen species. It was found that the intercalation of the urea precursor helped to stabilize the layered structures of both lamellar solid acids and enabled easier nitrogen doping. The effects of urea intercalation were more significant for the more acidic HNb(3)O(8) sample than for the less acidic H(2)Ti(4)O(9). Compared with the nitrogen-doped KNb(3)O(8) and K(2)Ti(4)O(9) samples, the nitrogen-doped HNb(3)O(8) and H(2)Ti(4)O(9) solid acids absorb more visible light and exhibit a superior activity for RhB photodegradation under visible-light irradiation. The nitrogen-doped HNb(3)O(8) sample performed the best among all the samples. The results of the current study suggest that the protonic acidity of the lamellar solid-acid sample is a key factor that influences nitrogen doping and the resultant visible-light photocatalysis.

  7. GREEN CORE HOUSE

    Directory of Open Access Journals (Sweden)

    NECULAI Oana

    2017-05-01

    Full Text Available The Green Core House is a construction concept with low environmental impact, having as main central element a greenhouse. The greenhouse has the innovative role to use the biomass energy provided by plants to save energy. Although it is the central piece, the greenhouse is not the most innovative part of the Green Core House, but the whole building ensemble because it integrates many other sustainable systems as "waste purification systems", "transparent photovoltaic panels" or "double skin façades".

  8. Birefringent hollow core fibers

    DEFF Research Database (Denmark)

    Roberts, John

    2007-01-01

    Hollow core photonic crystal fiber (HC-PCF), fabricated according to a nominally non-birefringent design, shows a degree of un-controlled birefringence or polarization mode dispersion far in excess of conventional non polarization maintaining fibers. This can degrade the output pulse in many...... and an increased overlap between the polarization modes at the glass interfaces. The interplay between these effects leads to a wavelength for optimum polarization maintenance, lambda(PM), which is detuned from the wavelength of highest birefringence. By a suitable fiber design involving antiresonance of the core...

  9. CORE COMPONENT POT

    Energy Technology Data Exchange (ETDEWEB)

    MARTIN RL; OMBERG RP

    1975-12-19

    The core component pot is an open top vessel used to hold both new and irradiated core components for storage in the IDS and for holding the components submerged in sodium while being trasported inside CLEM. The top of the CCP is equipped with a grapple lip which is engaged by the hoisting grapples. Heat for maintaining the preheat of new components and dissipation of decay heat of irradiated fuel assemblies is conducted between the wall of the pot and the surrounding environment by thermal radiation and convection.

  10. Biological artificial fluid-induced non-lamellar phases in glyceryl monooleate: the kinetics pathway and its digestive process by bile salts.

    Science.gov (United States)

    Zhou, Yanyan; Wang, Qifang; Wang, Yan; Xu, Hui; Yuan, Bo; Li, Sanming; Liu, Hongzhuo

    2014-02-01

    The cubic (Q(II)) phase is a promising sustained-release system. However, its rigid gel-like propensity is highly viscous, which makes it difficult to handle in pharmaceutical applications. To circumvent this problem, a less viscous lamellar (L(α)) phase that could spontaneously transform to Q(II) phase by the introduction of water or biological artificial fluid can be used. However, the kinetics pathway of phase transition, susceptibility to digestive processes and impact of the transition on drug release are not yet well understood. We investigated various biological artificial fluid-induced L(α) to inverse Q(II) phase transition over time in glyceryl monooleate (GMO) by water penetration scan and light polarizing microscopy. To reveal the structure stability, fluorescence spectroscopy studies were conducted using pyrene as a probe. Furthermore, the release mechanism of pyrene as a lipophilic drug model in the spontaneously formed Q(II) was investigated. Although hexagonal (H(II)) mesophases occurred when phosphate buffered saline (PBS) 7.4, 0.1 M HCl or sodium taurocholate (NaTC) solutions were introduced to GMO at room temperature, they disappear with the exception of 0.1 M HCl at 37 °C. Compared with 25 °C, L(α) to Q(II) phase transition was in a faster rate as almost completely transforms were observed after 2 h post-immersion. The spontaneously formed mesophases were stable over 24 h immersions in PBS or pancreatic lipase solutions as proven by the extremely low fluorescence signal, however they were digestible by bile salts. This result indicated that digestion by bile salts was the major pathway instead of digestion by lipases. Moreover, pyrene fluorescence spectroscopy confirmed that the digestion by bile salts induced the formation of GMO-bile salt mixed micelles whose performance depended on the bile salt concentrations. This dependence influenced the drug release from the spontaneously formed Q(II) phase. All the results concluded that

  11. Maximum stellar iron core mass

    Indian Academy of Sciences (India)

    An analytical method of estimating the mass of a stellar iron core, just prior to core collapse, is described in this paper. The method employed depends, in part, upon an estimate of the true relativistic mass increase experienced by electrons within a highly compressed iron core, just prior to core collapse, and is significantly ...

  12. Comparison of visual and topographic outcomes of deep-anterior lamellar keratoplasty and penetrating keratoplasty in keratoconus

    Directory of Open Access Journals (Sweden)

    Bora Yüksel

    2017-03-01

    Full Text Available AIM: To compare visual, surgical and topographic outcomes of deep anterior lamellar keratoplasty (DALK and penetrating keratoplasty (PK for keratoconus (KC. METHODS: In this multicenter, prospective, randomized clinical trial 76 eyes of 71 KC patients operated between January 2011 and July 2014 in 2 tertiary referral hospitals were included. Consecutive patients were alternately selected to receive one of the two surgical methods. Thirty eight eyes underwent DALK with the big-bubble technique and 38 eyes underwent PK. RESULTS: Mean best spectacle corrected visual acuity (BSCVA at the first postoperative week (P=0.012 and the first postoperative month (P<0.001 was statistically significantly higher in DALK group. The mean BSCVA at 12mo was not significantly different for DALK (0.30±1.99 logMAR versus PK (0.40±0.33 logMAR (P=0.104. The 76.3% of the eyes had a BSCVA over 0.5 in DALK and 47.4% in PK group (P=0.009. The 7.9% of the eyes had a BSCVA of 1.0 in DALK and 5.3% in PK group (P=0.644. Mean spherical equivalent was -2.94 D in DALK and -3.09 D in PK group. Mean topographic astigmatism was 4.62 D and 4.18 D respectively. Regular topographic patterns were observed in 31 (81.6% of DALK and 29 (76.3% of PK (P=0.574. The most frequent topographic pattern was oblate asymmetric bow tie, seen in 39.5% in DALK and 23.7% in PK. CONCLUSION: Big bubble DALK provides an earlier visual improvement compare to PK. However, visual and topographic outcomes are similar to those in PK at 1y. Postoperative complications including rejection and intraocular pressure elevation are more frequent in PK. DALK is a safer alternative to PK for KC. However, intraoperative perforation of the Descemet’s membrane is a significant complication.

  13. Efficacy and safety of deep anterior lamellar keratoplasty vs. penetrating keratoplasty for keratoconus: a meta-analysis.

    Directory of Open Access Journals (Sweden)

    Hao Liu

    Full Text Available To evaluate difference in therapeutic outcomes between deep anterior lamellar keratoplasty (DALK and penetrating keratoplasty (PKP for the clinical treatment of keratoconus.A comprehensive search was conducted in Pubmed, EMBASE, Cochrane Library, and Web of science. Eligible studies should include at least one of the following factors: best corrected visual acuity (BCVA, postoperative spherical equivalent (SE, postoperative astigmatism and endothelial cell count (ECC, central corneal thickness (CCT, graft rejection and graft failure, of which BCVA, graft rejection and graft failure were used as the primary outcome measures, and postoperative SE, astigmatism, CCT and ECC as the secondary outcome measures. Given the lack of randomized clinical trials (RCTs, cohort studies and prospective studies were considered eligible.Sixteen clinical trials involving 6625 eyes were included in this review, including 1185 eyes in DALK group, and 5440 eyes in PKP group. The outcomes were analyzed using Cochrane Review Manager (RevMan version 5.0 software. The postoperative BCVA in DALK group was significantly better than that in PKP group (OR = 0.48; 95%CI 0.39 to 0.60; p<0.001. There were fewer cases of graft rejection in DALK group than those in PKP group (OR = 0.28; 95%CI 0.15 to 0.50; p<0.001. Nevertheless the rate of graft failure was similar between DALK and PKP groups (OR = 1.05; 95%CI 0.81 to 1.36; p = 0.73. There were no significant differences in the secondary outcomes of SE (p = 0.70, astigmatism (p = 0.14 and CCT (p = 0.58 between DALK and PKP groups. And ECC in DALK group was significantly higher than PKP group (p<0.001. The postoperative complications, high intraocular pressure (high-IOP and cataract were analyzed, fewer cases of complications occurred in DALK group than those in PKP group (high-IOP, OR 0.22, 95% CI 0.11-0.44, P<0.001 (cataract, OR 0.22; 95% CI 0.08-0.61, P = 0.004. And no cases of expulsive hemorrhage and endophthalmitis were

  14. Inflation targeting and core inflation

    OpenAIRE

    Julie Smith

    2005-01-01

    This paper examines the interaction of core inflation and inflation targeting as a monetary policy regime. Interest in core inflation has grown because of inflation targeting. Core inflation is defined in numerous ways giving rise to many potential measures; this paper defines core inflation as the best forecaster of inflation. A cross-country study finds before the start of inflation targeting, but not after, core inflation differs between non-inflation targeters and inflation targeters. Thr...

  15. NUCLEAR REACTOR CORE DESIGN

    Science.gov (United States)

    Mahlmeister, J.E.; Peck, W.S.; Haberer, W.V.; Williams, A.C.

    1960-03-22

    An improved core design for a sodium-cooled, graphitemoderated nuclear reactor is described. The improved reactor core comprises a number of blocks of moderator material, each block being in the shape of a regular prism. A number of channels, extending the length of each block, are disposed around the periphery. When several blocks are placed in contact to form the reactor core, the channels in adjacent blocks correspond with each other to form closed conduits extending the length of the core. Fuel element clusters are disposed in these closed conduits, and liquid coolant is forced through the annulus between the fuel cluster and the inner surface of the conduit. In a preferred embodiment of the invention, the moderator blocks are in the form of hexagonal prisms with longitudinal channels cut into the corners of the hexagon. The main advantage of an "edge-loaded" moderator block is that fewer thermal neutrons are absorbed by the moderator cladding, as compared with a conventional centrally loaded moderator block.

  16. Schumpeter's core works revisited

    DEFF Research Database (Denmark)

    Andersen, Esben Sloth

    2012-01-01

    This paper organises Schumpeter’s core books in three groups: the programmatic duology,the evolutionaryeconomic duology,and the socioeconomic synthesis. By analysing these groups and their interconnections from the viewpoint of modern evolutionaryeconomics,the paper summarises resolved problems...

  17. Core Obstetrics and Gynaecology*

    African Journals Online (AJOL)

    Core Obstetrics and Gynaecology*. By J. T. Nel. Pp xvii + 992. Illustrated. Durban: Butterworths. 1995. ISBN 0-409-10134-6. For some years now, I have lamented the absence of a good, home-grown, comprehensive, student-centred textbook of obstetrics and gynaecology designed specifically for South African needs.

  18. Adult educators' core competences

    DEFF Research Database (Denmark)

    Wahlgren, Bjarne

    2016-01-01

    environment as well as the kind of adult education concerned (e.g. basic education, work-related education etc.). However, it seems that it is possible to identify certain competence requirements which transcend national, cultural and functional boundaries. This research note summarises these common or “core...

  19. The core and cosmopolitans

    DEFF Research Database (Denmark)

    Dahlander, Linus; Frederiksen, Lars

    2012-01-01

    Users often interact and help each other solve problems in communities, but few scholars have explored how these relationships provide opportunities to innovate. We analyze the extent to which people positioned within the core of a community as well as people that are cosmopolitans positioned...

  20. Looking for Core Values

    Science.gov (United States)

    Carter, Margie

    2010-01-01

    People who view themselves as leaders, not just managers or teachers, are innovators who focus on clarifying core values and aligning all aspects of the organization with these values to grow their vision. A vision for an organization can't be just one person's idea. Visions grow by involving people in activities that help them name and create…

  1. Some Core Contested Concepts

    Science.gov (United States)

    Chomsky, Noam

    2015-01-01

    Core concepts of language are highly contested. In some cases this is legitimate: real empirical and conceptual issues arise. In other cases, it seems that controversies are based on misunderstanding. A number of crucial cases are reviewed, and an approach to language is outlined that appears to have strong conceptual and empirical motivation, and…

  2. Modeling Core Collapse Supernovae

    Science.gov (United States)

    Mezzacappa, Anthony

    2017-01-01

    Core collapse supernovae, or the death throes of massive stars, are general relativistic, neutrino-magneto-hydrodynamic events. The core collapse supernova mechanism is still not in hand, though key components have been illuminated, and the potential for multiple mechanisms for different progenitors exists. Core collapse supernovae are the single most important source of elements in the Universe, and serve other critical roles in galactic chemical and thermal evolution, the birth of neutron stars, pulsars, and stellar mass black holes, the production of a subclass of gamma-ray bursts, and as potential cosmic laboratories for fundamental nuclear and particle physics. Given this, the so called ``supernova problem'' is one of the most important unsolved problems in astrophysics. It has been fifty years since the first numerical simulations of core collapse supernovae were performed. Progress in the past decade, and especially within the past five years, has been exponential, yet much work remains. Spherically symmetric simulations over nearly four decades laid the foundation for this progress. Two-dimensional modeling that assumes axial symmetry is maturing. And three-dimensional modeling, while in its infancy, has begun in earnest. I will present some of the recent work from the ``Oak Ridge'' group, and will discuss this work in the context of the broader work by other researchers in the field. I will then point to future requirements and challenges. Connections with other experimental, observational, and theoretical efforts will be discussed, as well.

  3. Core calculations of JMTR

    Energy Technology Data Exchange (ETDEWEB)

    Nagao, Yoshiharu [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment

    1998-03-01

    In material testing reactors like the JMTR (Japan Material Testing Reactor) of 50 MW in Japan Atomic Energy Research Institute, the neutron flux and neutron energy spectra of irradiated samples show complex distributions. It is necessary to assess the neutron flux and neutron energy spectra of an irradiation field by carrying out the nuclear calculation of the core for every operation cycle. In order to advance core calculation, in the JMTR, the application of MCNP to the assessment of core reactivity and neutron flux and spectra has been investigated. In this study, in order to reduce the time for calculation and variance, the comparison of the results of the calculations by the use of K code and fixed source and the use of Weight Window were investigated. As to the calculation method, the modeling of the total JMTR core, the conditions for calculation and the adopted variance reduction technique are explained. The results of calculation are shown. Significant difference was not observed in the results of neutron flux calculations according to the difference of the modeling of fuel region in the calculations by K code and fixed source. The method of assessing the results of neutron flux calculation is described. (K.I.)

  4. The Uncommon Core

    Science.gov (United States)

    Ohler, Jason

    2013-01-01

    This author contends that the United States neglects creativity in its education system. To see this, he states, one may look at the Common Core State Standards. If one searches the English Language Arts and Literacy standards for the words "creative," "innovative," and "original"--and any associated terms, one will…

  5. Resolução lamelar num novo microscópio eletrônico de varredura Lamellar resolution in a new scanning electron microscope

    Directory of Open Access Journals (Sweden)

    Hans-Jürgen Kestenbach

    1997-03-01

    Full Text Available RESUMO: Trabalhando com elétrons de baixa energia (na faixa de 1keV, o novo microscópio eletrônico de varredura dispensa a etapa de metalização e permite a observação direta da estrutura lamelar de polímeros semicristalinos, sem a necessidade de preparação de amostras. São apresentados exemplos da morfologia lamelar do PVDF em função das condições de processamento e da temperatura de cristalização, em filmes contendo as fases a, b e g. Um outro exemplo revela o crescimento inicial da camada transcristalina que se formou ao longo de uma fibra de polietileno de ultra-alto peso molecular embutida em matriz de polietileno de alta densidade.ABSTRACT: Working with low energy electrons (in the range of 1keV, the new scanning electron microscope permits the lamellar (supermolecular structure of semicrystalline polymers to be observed directly without the need of specimen coating or of any other sample preparation technique. Microscope performance is demonstrated by several examples of high resolution micrographs which show spherulitic, lamellar and fibrilar morphologies developed by the a, b and g phases of PVDF as a function of processing conditions and crystallization temperature. Another example reveals the early stages of transcrystalline layer formation in HDPE reinforced by UHMWPE fibers.

  6. Ring-shaped corneoscleral lamellar keratoplasty guided by high-definition optical coherence tomography and Scheimpflug imaging for severe Terrien's marginal corneal degeneration.

    Science.gov (United States)

    Wang, Ting; Shi, Weiyun; Ding, Gang; Li, Suxia; Liu, Mingna; Gao, Hua

    2012-12-01

    To evaluate the clinical efficacy of ring-shaped corneoscleral lamellar keratoplasty under guidance of high-definition optical coherence tomography (HD-OCT) and Scheimpflug imaging for severe Terrien's marginal corneal degeneration. Twenty-five patients (25 eyes) with Terrien's marginal corneal degeneration and  ≥ 6 diopters of astigmatism were treated at the Shandong Eye Institute from January 2008 through December 2010. In these patients, the diseased area was  > 1 quarter of the cornea, and the thickness at the thinnest corneal area was  keratoplasty was performed, and the depth and width of dissection was set according to the HD-OCT and Pentacam examinations. Data of complications, surgical effects, visual acuity, and astigmatism were collected. No intraoperative corneal perforation occurred. No patients had liquid accumulation between the graft and the recipient. At 1 year after surgery, the average best-corrected visual acuity improved to 6/9 from preoperative 6/36, and the average astigmatism reduced to 4.37 (2.04) diopters from preoperative 13.39 (7.52) diopters. There was no recurrence of the disease or corneal graft rejection in the follow-up period. Ring-shaped corneoscleral lamellar keratoplasty guided by HD-OCT and Pentacam imaging appears to be effective in the treatment of severe Terrien's marginal corneal degeneration. Surgical perforation can be significantly reduced.

  7. Effect of reinforcement surface functionalization on the mechanical properties of nacre-like bulk lamellar composites processed by a hybrid conventional method.

    Science.gov (United States)

    Gurbuz, Selen N; Dericioglu, Arcan F

    2013-05-01

    Alumina platelet reinforced epoxy matrix composites with an architecture resembling to natural nacre were fabricated by a hybrid conventional method called Hot-press Assisted Slip Casting process (HASC). Correlation between processing parameters, platelet content, platelet orientation and mechanical property enhancement of the fabricated composites was examined. In order to investigate the effect of interfacial compatibility and bonding on the mechanical properties of the fabricated inorganic-organic composites, platelet surfaces were modified with both epoxy- and amino-functional silanes. As received and functionalized platelet surfaces were studied by X-Ray Photoelectron Spectroscopy (XPS) to confirm the success of surface modification. Fabricated bio-inspired bulk lamellar composite materials were characterized in terms of their microstructural architecture and mechanical properties. The results obtained indicated that HASC processed composites exhibit enhanced flexural strength, stiffness and hardness, as compared to neat epoxy and composites fabricated by simple mixing, as a result of their nacre-like architecture with well aligned platelets. It has been also observed that functionalization by both type of silanes improves interfacial adhesion between platelets and epoxy matrix resulting in further enhancement of the mechanical properties of bulk lamellar composites fabricated by HASC. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Gene transfer into rabbit keratocytes using AAV and lipid-mediated plasmid DNA vectors with a lamellar flap for stromal access.

    Science.gov (United States)

    Mohan, Rajiv R; Schultz, Gregory S; Hong, Jong Wook; Mohan, Rahul R; Wilson, Steven E

    2003-03-01

    Development of gene transfer methods that can precisely deliver therapeutic genes to the localized or targeted tissue(s) would be highly beneficial in developing new gene therapy approaches and may also extend animal models for studying in vivo gene function and regulation at molecular levels in the selected tissues. We investigated lipid- and AAV-mediated gene transfer in rabbit cornea using a lamellar flap-technique. The goals of this study were to (1) analyze methods for in situ gene transfer into keratocytes, (2) identify efficient and suitable vectors for gene transfer into keratocytes, and (3) characterize times of first detectable expression, localization and duration of transgene expression in keratocytes with different vectors. A lamellar flap was produced in the rabbit cornea with a microkeratome. Recombinant adeno-associated viral vector (rAAV) expressing either beta-galactosidase (rAAV-beta-gal) or chloramphenicol acetyltransferase (rAAV-CAT) reporter genes, or plasmid-cationic lipid complexes expressing CAT (pMP6-CAT) or beta-galactosidase (pTR-beta-gal) were applied beneath the lamellar flap for two minutes. The flap was repositioned and eyelids sutured overnight. Corneas were removed at 4hr, 12hr, 36hr, 3 days, 7 days, or 10 days after application and either fixed in 2% formaldehyde, cryosectioned and stained for beta-galactosidase activity or homogenized and measured for CAT levels by ELISA. Corneas infected with rAAV-beta-gal vector showed positive beta-gal staining in the center and periphery of the flap interface in whole corneas and corneal beds at 3, 7, and 10 days, but not at earlier time points. Corneas treated with pTR-beta-gal plasmid vector showed positive beta-gal expression at the interface at 4, 12 and 36hr, but not at 3 or 7 days. The posterior surface of the lamellar interface where the vector was applied showed more expression than the overlying anterior surface with both plasmid and viral vectors. The level of gene expression was

  9. Measuring core stability.

    Science.gov (United States)

    Liemohn, Wendell P; Baumgartner, Ted A; Gagnon, Laura H

    2005-08-01

    In this study, a 4-item battery of core stability (CS) tests modeled on core stabilization activities used in training and rehabilitation research was developed, and a measurement schedule was established to maximize internal consistency and stability reliabilities. Specifically, we found that 4 test administrations on each of 4 days produced intraclass correlation coefficients that in most instances exceeded 0.90 and stability reliability coefficients on the third and fourth days of testing that exceeded 0.90 for 2 of the tests and 0.80 for the other 2. Thus, it is recommended that in future research, examiners administer the battery for at least 3 days and consider the data collected on day 3 as the best estimate of participant CS.

  10. Core Outlet Temperature Study

    Energy Technology Data Exchange (ETDEWEB)

    Moisseytsev, A. [Argonne National Laboratory (ANL), Argonne, IL (United States); Hoffman, E. [Argonne National Laboratory (ANL), Argonne, IL (United States); Majumdar, S. [Argonne National Laboratory (ANL), Argonne, IL (United States)

    2008-07-28

    It is a known fact that the power conversion plant efficiency increases with elevation of the heat addition temperature. The higher efficiency means better utilization of the available resources such that higher output in terms of electricity production can be achieved for the same size and power of the reactor core or, alternatively, a lower power core could be used to produce the same electrical output. Since any nuclear power plant, such as the Advanced Burner Reactor, is ultimately built to produce electricity, a higher electrical output is always desirable. However, the benefits of the higher efficiency and electricity production usually come at a price. Both the benefits and the disadvantages of higher reactor outlet temperatures are analyzed in this work.

  11. Ice Cores of the National Ice Core Laboratory

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The U.S. National Ice Core Laboratory (NICL) is a facility for storing, curating, and studying ice cores recovered from the polar regions of the world. It provides...

  12. Core Exercises: Why You Should Strengthen Your Core Muscles

    Science.gov (United States)

    ... neglected. Still, it pays to get your core muscles — the muscles around your trunk and pelvis — in better shape. ... to find out why. Core exercises train the muscles in your pelvis, lower back, hips and abdomen ...

  13. USGS Core Research Center (CRC) Collection of Core

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Core Research Center (CRC) was established in 1974 by the U.S. Geological Survey (USGS) to preserve valuable rock cores for use by scientists and educators from...

  14. Leadership Core Competencies

    Science.gov (United States)

    2008-03-15

    different approaches led to a very similar understanding of what is required to develop leaders and achieve mission success. LEADERSHIP CORE... Leadership , the first principle, Know yourself and seek self-improvement performs the same function. Similar to the other services, Navy leaders evaluate... leadership styles. Like managers of today, those of tomorrow will also need to do more with less. They will have increased responsibilities and will

  15. Optimizing performance by improving core stability and core strength.

    Science.gov (United States)

    Hibbs, Angela E; Thompson, Kevin G; French, Duncan; Wrigley, Allan; Spears, Iain

    2008-01-01

    Core stability and core strength have been subject to research since the early 1980s. Research has highlighted benefits of training these processes for people with back pain and for carrying out everyday activities. However, less research has been performed on the benefits of core training for elite athletes and how this training should be carried out to optimize sporting performance. Many elite athletes undertake core stability and core strength training as part of their training programme, despite contradictory findings and conclusions as to their efficacy. This is mainly due to the lack of a gold standard method for measuring core stability and strength when performing everyday tasks and sporting movements. A further confounding factor is that because of the differing demands on the core musculature during everyday activities (low load, slow movements) and sporting activities (high load, resisted, dynamic movements), research performed in the rehabilitation sector cannot be applied to the sporting environment and, subsequently, data regarding core training programmes and their effectiveness on sporting performance are lacking. There are many articles in the literature that promote core training programmes and exercises for performance enhancement without providing a strong scientific rationale of their effectiveness, especially in the sporting sector. In the rehabilitation sector, improvements in lower back injuries have been reported by improving core stability. Few studies have observed any performance enhancement in sporting activities despite observing improvements in core stability and core strength following a core training programme. A clearer understanding of the roles that specific muscles have during core stability and core strength exercises would enable more functional training programmes to be implemented, which may result in a more effective transfer of these skills to actual sporting activities.

  16. Hollow-Core Fiber Lamp

    Science.gov (United States)

    Yi, Lin (Inventor); Tjoelker, Robert L. (Inventor); Burt, Eric A. (Inventor); Huang, Shouhua (Inventor)

    2016-01-01

    Hollow-core capillary discharge lamps on the millimeter or sub-millimeter scale are provided. The hollow-core capillary discharge lamps achieve an increased light intensity ratio between 194 millimeters (useful) and 254 millimeters (useless) light than conventional lamps. The capillary discharge lamps may include a cone to increase light output. Hollow-core photonic crystal fiber (HCPCF) may also be used.

  17. On core stability and extendability

    OpenAIRE

    Shellshear, Evan

    2011-01-01

    This paper investigates conditions under which the core of a TU cooperative game is stable. In particular the author extends the idea of extendability to find new conditions under which the core is stable. It is also shown that these new conditions are not necessary for core stability.

  18. Maximum stellar iron core mass

    Indian Academy of Sciences (India)

    Abstract. An analytical method of estimating the mass of a stellar iron core, just prior to core collapse, is .... approximately as an ideal gas, the mean kinetic energies of the free electrons and atomic nuclei will be equal. .... whose density varies from a maximum at the core's center to a minimum at its 'surface'. The dimensional ...

  19. Dual-core Itanium Processor

    CERN Multimedia

    2006-01-01

    Intel’s first dual-core Itanium processor, code-named "Montecito" is a major release of Intel's Itanium 2 Processor Family, which implements the Intel Itanium architecture on a dual-core processor with two cores per die (integrated circuit). Itanium 2 is much more powerful than its predecessor. It has lower power consumption and thermal dissipation.

  20. Fusion-activated Ca(2+ entry: an "active zone" of elevated Ca(2+ during the postfusion stage of lamellar body exocytosis in rat type II pneumocytes.

    Directory of Open Access Journals (Sweden)

    Pika Miklavc

    2010-06-01

    Full Text Available Ca(2+ is essential for vesicle fusion with the plasma membrane in virtually all types of regulated exocytoses. However, in contrast to the well-known effects of a high cytoplasmic Ca(2+ concentration ([Ca(2+](c in the prefusion phase, the occurrence and significance of Ca(2+ signals in the postfusion phase have not been described before.We studied isolated rat alveolar type II cells using previously developed imaging techniques. These cells release pulmonary surfactant, a complex of lipids and proteins, from secretory vesicles (lamellar bodies in an exceptionally slow, Ca(2+- and actin-dependent process. Measurements of fusion pore formation by darkfield scattered light intensity decrease or FM 1-43 fluorescence intensity increase were combined with analysis of [Ca(2+](c by ratiometric Fura-2 or Fluo-4 fluorescence measurements. We found that the majority of single lamellar body fusion events were followed by a transient (t(1/2 of decay = 3.2 s rise of localized [Ca(2+](c originating at the site of lamellar body fusion. [Ca(2+](c increase followed with a delay of approximately 0.2-0.5 s (method-dependent and in the majority of cases this signal propagated throughout the cell (at approximately 10 microm/s. Removal of Ca(2+ from, or addition of Ni(2+ to the extracellular solution, strongly inhibited these [Ca(2+](c transients, whereas Ca(2+ store depletion with thapsigargin had no effect. Actin-GFP fluorescence around fused LBs increased several seconds after the rise of [Ca(2+](c. Both effects were reduced by the non-specific Ca(2+ channel blocker SKF96365.Fusion-activated Ca(2+entry (FACE is a new mechanism that leads to [Ca(2+](c transients at the site of vesicle fusion. Substantial evidence from this and previous studies indicates that fusion-activated Ca(2+ entry enhances localized surfactant release from type II cells, but it may also play a role for compensatory endocytosis and other cellular functions.

  1. Replacing the endothelium without corneal surface incisions or sutures: the first United States clinical series using the deep lamellar endothelial keratoplasty procedure.

    Science.gov (United States)

    Terry, Mark A; Ousley, Paula J

    2003-04-01

    To report the 6- and 12-month results of the first United States clinical series of deep lamellar endothelial keratoplasty (DLEK) in the treatment of endothelial dysfunction. Prospective, noncomparative, interventional case series. Eight eyes of eight patients with corneal edema from Fuchs' dystrophy and pseudophakia. A 9.0-mm limbal, scleral, partial-depth incision provided access for a deep lamellar corneal pocket dissection. A 7.5- to 8.0-mm posterior lamellar disc of recipient tissue was then excised and replaced through the pocket with a same size donor disc containing healthy endothelium. A temporary air bubble in the anterior chamber was used for donor tissue adherence, and no surface corneal incisions or sutures were necessary. Preoperative and postoperative best spectacle-corrected visual acuity (BSCVA), manifest refraction astigmatism, TMS-1 topography, ultrasonic pachymetry, Orbscan topography, and endothelial cell density were evaluated. Intraoperative and postoperative complications are reported. At 6 and 12 months after surgery, all eight corneas were clear and the grafts were healed in good position. At 6 months, the BSCVA varied between 20/30 and 20/70, the average change in astigmatism from before surgery was +1.13 diopters (D; +/-1.50 D), the average change in corneal power was -0.4 D (+/-1.7 D), the average pachymetry was 648 micro m (+/-134 micro m), and the average endothelial cell count was 2290 cells/mm(2) (+/-372 cells/mm(2)). At 12 months, three of the four eyes reaching this time gate were 20/40 or better, with a change in astigmatism from before surgery of only +0.81 D (+/- 0.55 D), a corneal power change of -1.3 D (+/- 0.4 D), and an endothelial density of 2409 cells/mm(2) (+/- 154 cells/mm(2)). One of the original nine eyes entered into this study required conversion to standard penetrating keratoplasty as a result of a microperforation during recipient pocket dissection and has experienced no ill effects. The DLEK procedure, with its

  2. Full MOX core for ABWR

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Yuki; Yoshioka, Ritsuo; Nagano, Mamoru [Toshiba Corp., Kawasaki, Kanagawa (Japan)

    1996-08-01

    The Japan Atomic Energy Commission has announced the construction plan for an advanced boiling-water reactor (ABWR) with a full MOX (mixed oxide) core instead of ATR. Increased MOX fuel utilization will result in greater savings of uranium ore. A full MOX core for a power plant requires flexibility in MOX fuel utilization, steadiness, and economical operation. We have proposed the optimum full MOX core design for an ABWR based on the MOX fuel and core technologies that we have developed over a period of many years, as well as our considerable experience in uranium fuel and cores. Our full MOX core design for an ABWR has good core characteristics and safety performance with no change in the basic design specifications of the current ABWR. (author)

  3. Potential for low fracture toughness and lamellar tearing on PWR steam generator and reactor coolant pump supports. Resolution of generic technical activity A-12

    Energy Technology Data Exchange (ETDEWEB)

    Snaider, R.P.; Hodge, J.M.; Levin, H.A.; Zudans, J.J.

    1979-10-01

    This report summarizes work performed by the Nuclear Regulatory Commission staff and its contractor, Sandia Laboratories, in the resolution of Generic Technical Activity A-12, ''Potential for Low Fracture Toughness and Lamellar Tearing in PWR Steam Generator and Reactor Coolant Pump Supports.'' The report describes the technical issues, the technical studies performed by Sandia describes the technical issues, the technical studies performed by Sandia Laboratories, the NRC staff's technical positions based on these studies, and the staff's plan for implementing its technical positions. It also provides recommendations for further work. The complete technical input from Sandia Laboratories is appended to the report.

  4. Abca12-mediated lipid transport and Snap29-dependent trafficking of lamellar granules are crucial for epidermal morphogenesis in a zebrafish model of ichthyosis

    Directory of Open Access Journals (Sweden)

    Qiaoli Li

    2011-11-01

    Zebrafish (Danio rerio can serve as a model system to study heritable skin diseases. The skin is rapidly developed during the first 5–6 days of embryonic growth, accompanied by expression of skin-specific genes. Transmission electron microscopy (TEM of wild-type zebrafish at day 5 reveals a two-cell-layer epidermis separated from the underlying collagenous stroma by a basement membrane with fully developed hemidesmosomes. Scanning electron microscopy (SEM reveals an ordered surface contour of keratinocytes with discrete microridges. To gain insight into epidermal morphogenesis, we have employed morpholino-mediated knockdown of the abca12 and snap29 genes, which are crucial for secretion of lipids and intracellular trafficking of lamellar granules, respectively. Morpholinos, when placed on exon-intron junctions, were >90% effective in preventing the corresponding gene expression when injected into one- to four-cell-stage embryos. By day 3, TEM of abca12 morphants showed accumulation of lipid-containing electron-dense lamellar granules, whereas snap29 morphants showed the presence of apparently empty vesicles in the epidermis. Evaluation of epidermal morphogenesis by SEM revealed similar perturbations in both cases in the microridge architecture and the development of spicule-like protrusions on the surface of keratinocytes. These morphological findings are akin to epidermal changes in harlequin ichthyosis and CEDNIK syndrome, autosomal recessive keratinization disorders due to mutations in the ABCA12 and SNAP29 genes, respectively. The results indicate that interference of independent pathways involving lipid transport in the epidermis can result in phenotypically similar perturbations in epidermal morphogenesis, and that these fish mutants can serve as a model to study the pathomechanisms of these keratinization disorders.

  5. Optical coherence tomography characteristics of different types of big bubbles seen in deep anterior lamellar keratoplasty by the big bubble technique.

    Science.gov (United States)

    AlTaan, S L; Termote, K; Elalfy, M S; Hogan, E; Werkmeister, R; Schmetterer, L; Holland, S; Dua, H S

    2016-11-01

    PurposeTo define optical coherence tomography (OCT) characteristics of type-1, type-2, and mixed big bubbles (BB) seen in deep anterior lamellar keratoplasty.MethodsHuman sclero-corneal discs were obtained from UK (30) and Canada (16) eye banks. Air was injected into corneal stroma until a BB formed. UK samples were fixed in formalin before scanning with Fourier-domain (FD-OCT). One pair of each type of BB was scanned fresh. All BB obtained from Canada were scanned fresh with time-domain (TD-OCT). For each OCT machine used, type-1 BB from which Descemets membrane (DM) was partially peeled, were also scanned. The morphological characteristics of the scans were studied.ResultsFD-OCT of the posterior wall of type-1 (Dua's layer (DL) with DM) and type-2 BB (DM alone) both revealed a double-contour hyper-reflective curvilinear image with a hypo-reflective zone in between. The anterior line of type-2 BB was thinner than that seen with type-1 BB. In mixed BB, FD-OCT showed two separate curvilinear images. The anterior image was a single hyper-reflective line (DL), whereas the posterior image, representing the posterior wall of type-2 BB (DM) was made of two hyper-reflective lines with a dark space in between. TD-OCT images were similar with less defined component lines, but the entire extent of the BB could be visualised.ConclusionOn OCT examination the DM and DL present distinct features, which can help identify type-1, type-2, and mixed BB. These characteristics will help corneal surgeons interpret intraoperative OCT during lamellar corneal surgery.

  6. 'Blue bubble' technique: an ab interno approach for Descemet separation in deep anterior lamellar keratoplasty using trypan blue stained viscoelastic device.

    Science.gov (United States)

    Livny, Eitan; Bahar, Irit; Hammel, Naama; Nahum, Yoav

    2017-07-03

    In this study, we examined a novel variant of 'big-bubble' deep anterior lamellar keratoplasty using trypan-blue-stained viscoelastic device for the creation of a pre-descemetic bubble. Ten corneoscleral rims were mounted on an artificial anterior chamber (AC). The AC was filled with air through a limbal paracentesis. A Melles' triangulated spatula was inserted through the paracentesis, with its tip penetrating the AC, was then slightly retracted and pushed into the deep stroma above the roof of the paracentesis. A mixture of trypan blue and viscoelastic device (Healon, Abbott Medical Optics, Abbott Park, Illinois) was injected into this intra-stromal pocket using a 27-G cannula to create a pre-descemetic separation bubble. Bubble type and visualization of dyed viscoelastic device were noted. The method was later employed in three cases. In all 10 corneoscleral rims, the technique successfully created a visible pre-descemetic (type 1) bubble that could be expanded up to the predicted diameter of trephination. Subsequent trephination and the removal of corneal stroma were uneventful. In two out of four clinical cases, a type 1 bubble was created, while in two others, visco-dissection failed and dyed viscoelastic was seen in the AC. The presented technique holds promise of being a relatively easy to perform, predictable and well-controlled alternative for achieving a type 1 bubble during deep anterior lamellar keratoplasty surgery. The trypan-blue-stained viscoelastic device facilitates proper visualization and control of the separation bubble and assists in identifying the penetrance to the separation bubble prior to removal of the stromal cap. © 2017 Royal Australian and New Zealand College of Ophthalmologists.

  7. NEUTRONIC REACTOR CORE INSTRUMENT

    Science.gov (United States)

    Mims, L.S.

    1961-08-22

    A multi-purpose instrument for measuring neutron flux, coolant flow rate, and coolant temperature in a nuclear reactor is described. The device consists essentially of a hollow thimble containing a heat conducting element protruding from the inner wall, the element containing on its innermost end an amount of fissionsble materinl to function as a heat source when subjected to neutron flux irradiation. Thermocouple type temperature sensing means are placed on the heat conducting element adjacent the fissionable material and at a point spaced therefrom, and at a point on the thimble which is in contact with the coolant fluid. The temperature differentials measured between the thermocouples are determinative of the neutron flux, coolant flow, and temperature being measured. The device may be utilized as a probe or may be incorporated in a reactor core. (AE C)

  8. Full MOX core in BWR

    Energy Technology Data Exchange (ETDEWEB)

    Aoyama, Motoo [Power and Industrial Systems R and D Laboratory, Hitachi Ltd., Hitachi, Ibaraki (Japan)

    1999-12-01

    Studies on the core design, the fuel rod thermal-mechanical design and the safety evaluation have been summarized for the Full MOX-ABWR, loaded with MOX fuels up to 100% of the core. Fuel bundle configuration for MOX fuels is identical to the STEP II fuel design and the discharge burnup is about 33 GWd/t. Core performance evaluations and fuel rod thermal-mechanical design analyses have been performed, and it has been confirmed that the design criteria are satisfied with enough margin like the UO{sub 2} fuel loaded core. Safety analyses on transients and accidents have also been performed by considering the MOX fuel and core characteristics adequately through selecting appropriate input data for each safety analysis. All safety criteria are satisfied like the UO{sub 2} core. (author)

  9. Wire core reactor for NTP

    Science.gov (United States)

    Harty, R. B.

    1991-01-01

    The development of the wire core system for Nuclear Thermal Propulsion (NTP) that took place from 1963 to 1965 is discussed. A wire core consists of a fuel wire with spacer wires. It's an annular flow core having a central control rod. There are actually four of these, with beryllium solid reflectors on both ends and all the way around. Much of the information on the concept is given in viewgraph form. Viewgraphs are presented on design details of the wire core, the engine design, engine weight vs. thrust, a technique used to fabricate the wire fuel element, and axial temperature distribution.

  10. Biochemistry Instrumentation Core Technology Center

    Data.gov (United States)

    Federal Laboratory Consortium — The UCLA-DOE Biochemistry Instrumentation Core Facility provides the UCLA biochemistry community with easy access to sophisticated instrumentation for a wide variety...

  11. Characterizing the Core via K-Core Covers

    NARCIS (Netherlands)

    Sanchez, S.M.; Borm, P.E.M.; Estevez, A.

    2013-01-01

    This paper extends the notion of individual minimal rights for a transferable utility game (TU-game) to coalitional minimal rights using minimal balanced families of a specific type, thus defining a corresponding minimal rights game. It is shown that the core of a TU-game coincides with the core of

  12. Global Core Plasma Model

    Science.gov (United States)

    Gallagher, Dennis L.; Craven, Paul D.; Comfort, Richard H.

    1999-01-01

    Over 40 years of ground and spacecraft plasmaspheric measurements have resulted in many statistical descriptions of plasmaspheric properties. In some cases, these properties have been represented as analytical descriptions that are valid for specific regions or conditions. For the most part, what has not been done is to extend regional empirical descriptions or models to the plasmasphere as a whole. In contrast, many related investigations depend on the use of representative plasmaspheric conditions throughout the inner magnetosphere. Wave propagation, involving the transport of energy through the magnetosphere, is strongly affected by thermal plasma density and its composition. Ring current collisional and wave particle losses also strongly depend on these quantities. Plasmaspheric also plays a secondary role in influencing radio signals from the Global Positioning System satellites. The Global Core Plasma Model (GCPM) is an attempt to assimilate previous empirical evidence and regional models for plasmaspheric density into a continuous, smooth model of thermal plasma density in the inner magnetosphere. In that spirit, the International Reference Ionosphere is currently used to complete the low altitude description of density and composition in the model. The models and measurements on which the GCPM is currently based and its relationship to IRI will be discussed.

  13. Adult educators' core competences

    Science.gov (United States)

    Wahlgren, Bjarne

    2016-06-01

    Which competences do professional adult educators need? This research note discusses the topic from a comparative perspective, finding that adult educators' required competences are wide-ranging, heterogeneous and complex. They are subject to context in terms of national and cultural environment as well as the kind of adult education concerned (e.g. basic education, work-related education etc.). However, it seems that it is possible to identify certain competence requirements which transcend national, cultural and functional boundaries. This research note summarises these common or "core" requirements, organising them into four thematic subcategories: (1) communicating subject knowledge; (2) taking students' prior learning into account; (3) supporting a learning environment; and (4) the adult educator's reflection on his or her own performance. At the end of his analysis of different competence profiles, the author notes that adult educators' ability to train adult learners in a way which then enables them to apply and use what they have learned in practice (thus performing knowledge transfer) still seems to be overlooked.

  14. Espaço de cores

    OpenAIRE

    SANTANA, Claudia Feitosa; OIWA, Nestor Norio; COSTA, Marcelo Fernandes da; TIEDEMANN, Klaus Bruno; Silveira, Luiz Carlos de Lima; VENTURA, Dora Selma Fix

    2006-01-01

    O artigo apresenta definições para os termos espaço de cores e sistemas de cores; classifica, de acordo com David Brainard (2003), os sistemas de cores em dois grupos: aparência de cores e diferenças de cores. Dentre os diversos sistemas de cores existentes, o artigo descreve dois deles: o sistema de cores Munsell &– um dos mais utilizados entre os sistemas de aparência de cores &– e a descrição do sistema de cores CIE 1931 &– um dos mais utilizados dentre os sistemas de diferença de cores. F...

  15. The INTEGRAL Core Observing Programme

    DEFF Research Database (Denmark)

    Winkler, C.; Gehrels, N.; Lund, Niels

    1999-01-01

    The Core Programme of the INTEGRAL mission is defined as the portion of the scientific programme covering the guaranteed time observations for the INTEGRAL Science Working Team. This paper describes the current status of the Core Programme preparations and summarizes the key elements...... of the observing programme....

  16. Complicated Politics to the Core

    Science.gov (United States)

    McGuinn, Patrick

    2015-01-01

    People dislike the Common Core for several different reasons, and so it is important to disaggregate the sources of opposition and to assess and then to dispel some of the myths that have built up around it. It also is important to understand the unusual political alliances that have emerged in opposition to Common Core implementation and how they…

  17. Toward full MOX core design

    Energy Technology Data Exchange (ETDEWEB)

    Rouviere, G.; Guillet, J.L. [Cogema BCR/DSDP, 78 - Saint Quentin en Yvelines (France); Bruna, G.B.; Pelet, J. [FRAMATOME, 92 - Paris-La-Defense (France)

    1999-07-01

    This paper presents a selection of the main preliminary results of a study program sponsored by COGEMA and currently carried out by FRAMATOME. The objective of this study is to investigate the feasibility of full MOX core loading in a French 1300 MWe PWR, a recent and widespread standard nuclear power plant. The investigation includes core nuclear design, thermal hydraulic and systems aspects. (authors)

  18. Winning Cores in Parity Games

    DEFF Research Database (Denmark)

    Vester, Steen

    2016-01-01

    in their own right. In particular, we show that the winning core and the winning region for a player in a parity game are equivalently empty. Moreover, the winning core contains all fatal attractors but is not necessarily a dominion itself. Experimental results are very positive both with respect to quality...

  19. Anisotropic charged core envelope star

    Science.gov (United States)

    Mafa Takisa, P.; Maharaj, S. D.

    2016-08-01

    We study a charged compact object with anisotropic pressures in a core envelope setting. The equation of state is quadratic in the core and linear in the envelope. There is smooth matching between the three regions: the core, envelope and the Reissner-Nordström exterior. We show that the presence of the electric field affects the masses, radii and compactification factors of stellar objects with values which are in agreement with previous studies. We investigate in particular the effect of electric field on the physical features of the pulsar PSR J1614-2230 in the core envelope model. The gravitational potentials and the matter variables are well behaved within the stellar object. We demonstrate that the radius of the core and the envelope can vary by changing the parameters in the speed of sound.

  20. Waves in the core and mechanical core-mantle interactions

    DEFF Research Database (Denmark)

    Jault, D.; Finlay, Chris

    2015-01-01

    This Chapter focuses on time-dependent uid motions in the core interior, which can beconstrained by observations of the Earth's magnetic eld, on timescales which are shortcompared to the magnetic diusion time. This dynamics is strongly inuenced by the Earth's rapid rotation, which rigidies...... the motions in the direction parallel to the Earth'srotation axis. This property accounts for the signicance of the core-mantle topography.In addition, the stiening of the uid in the direction parallel to the rotation axis gives riseto a magnetic diusion layer attached to the core-mantle boundary, which would...

  1. Epistemology and ontology in core ontologies: FOLaw and LRI-Core, two core ontologies for law

    NARCIS (Netherlands)

    Breukers, J.A.P.J.; Hoekstra, R.J.

    2004-01-01

    For more than a decade constructing ontologies for legal domains, we, at the Leibniz Center for Law, felt really the need to develop a core ontology for law that would enable us to re-use the common denominator of the various legal domains. In this paper we present two core ontologies for law. The

  2. ICF Core Sets for stroke.

    Science.gov (United States)

    Geyh, Szilvia; Cieza, Alarcos; Schouten, Jan; Dickson, Hugh; Frommelt, Peter; Omar, Zaliha; Kostanjsek, Nenad; Ring, Haim; Stucki, Gerold

    2004-07-01

    To report on the results of the consensus process integrating evidence from preliminary studies to develop the first version of the Comprehensive ICF Core Set and the Brief ICF Core Set for stroke. A formal decision-making and consensus process integrating evidence gathered from preliminary studies was followed. Preliminary studies included a Delphi exercise, a systematic review, and an empirical data collection. After training in the ICF and based on these preliminary studies relevant ICF categories were identified in a formal consensus process by international experts from different backgrounds. The preliminary studies identified a set of 448 ICF categories at the second, third and fourth ICF levels with 193 categories on body functions, 26 on body structures, 165 on activities and participation, and 64 on environmental factors. Thirty-nine experts from 12 different countries attended the consensus conference on stroke. Altogether 130 second-level categories were included in the Comprehensive ICF Core Set with 41 categories from the component body functions, 5 from body structures, 51 from activities and participation, and 33 from environmental factors. The Brief ICF Core Set included a total of 18 second-level categories (6 on body functions, 2 on body structures, 7 on activities and participation, and 3 on environmental factors). A formal consensus process integrating evidence and expert opinion based on the ICF framework and classification led to the definition of ICF Core Sets for stroke. Both the Comprehensive ICF Core Set and the Brief ICF Core Set were defined.

  3. Discovery of the Earth's core

    Science.gov (United States)

    Brush, Stephen G.

    1980-09-01

    In 1896 when Emil Wiechert proposed his model of the Earth with an iron core and stony shell, scientists generally believed that the entire earth was a solid as rigid as steel. R. D. Oldham's identification of P and S waves in seismological records allowed him to detect a discontinuity corresponding to a boundary between core and shell (mantle) in 1906, and Beno Gutenberg established the depth of this boundary as 2900 km. But failure to detect propagation of S waves through the core was not sufficient evidence to persuade seismologists that it is fluid (contrary to modern textbook statements). Not until 1926 did Harold Jeffreys refute the arguments for solidity and establish that the core is liquid. In 1936 Inge Lehmann discovered the small inner core. K. E. Bullen argued, on the basis of plausible assumptions about compressibility and density, that the inner core is solid. Attempts to find seismic signals that have passed through the inner core as S waves have so far failed (with one possible exception), but analysis of free oscillations provided fairly convincing evidence for its solidity.

  4. Core physics analysis of 100% MOX Core in IRIS

    Energy Technology Data Exchange (ETDEWEB)

    Franceschini, F.; Petrovic, B. [Westinghouse Electric Company LLC, Science and Technology Dept., 1344 Beulah Road, Pittsburgh, PA 15235 (United States)

    2006-07-01

    International Reactor Innovative and Secure (IRIS) is an advanced small-to-medium-size (1000 MWt) Pressurized Water Reactor (PWR), targeting deployment around 2015. Its reference core design is based on the current Westinghouse UO{sub 2} fuel with less than 5% {sup 235}U, and the analysis has been previously completed confirming good performance. The full MOX fuel core is currently under evaluation as one of the alternatives for the second wave of IRIS reactors. A full 3-D neutronic analysis has been performed to examine main core performance parameters, such as critical boron concentration, peaking factors, discharge burnup, etc. The enhanced moderation of the IRIS fuel lattice facilitates MOX core design, and all the obtained results are within the requirements, confirming viability of this option from the reactor physics standpoint. (authors)

  5. Lipoplexes formed from sugar-based gemini surfactants undergo a lamellar-to-micellar phase transition at acidic pH. Evidence for a non-inverted membrane-destabilizing hexagonal phase of lipoplexes

    OpenAIRE

    Wasungu, Luc; Stuart, Marc C. A.; Scarzello, Marco; Engberts, Jan B. F. N.; Hoekstra, Dick

    2006-01-01

    The present study aims at a better understanding of the mechanism of transfection mediated by two sugar-based gemini surfactants GS1 and GS2. Previously, these gemini surfactants have been shown to be efficient gene vectors for transfection both in vitro and in vivo. Here, using Nile Red, a solvatochromic fluorescent probe, we investigated the phase behavior of these gemini surfactants in complexes with plasmid DNA, so-called lipoplexes. We found that these lipoplexes undergo a lamellar-to-no...

  6. Lamellar Liquid Crystal Improves the Skin Retention of 3-O-Ethyl-Ascorbic Acid and Potassium 4-Methoxysalicylate In Vitro and In Vivo for Topical Preparation.

    Science.gov (United States)

    Li, Yuanru; Dong, Cuilian; Cun, Dongmei; Liu, Jie; Xiang, Rongwu; Fang, Liang

    2016-06-01

    The study aimed at increasing the skin retention of 3-O-ethyl-ascorbic acid (EA) and potassium 4-methoxysalicylate (4-MSK) via topical administration for effective skin-whitening. To achieve this goal, EA and 4-MSK were formulated into lamellar liquid crystalline (LLC) cream, and response surface methodology (RSM) was employed to optimize the formulation. Polarized light microscopy (PLM), differential scanning calorimetry (DSC), and rheological experiments were performed to confirm the presence of the LLC structure in the base of cream. In addition, a comparison analysis of the skin retention of the two drugs between the LLC cream and the common o/w (COW) cream was made through in vitro permeation and in vivo drug distribution experiments. As a result, the optimal formulation was defined as 1.2% of EA, 1.48% of 4-MSK, 14.05% of Schercemol™ DISM Ester (DISM) as the oil, 4.0% of Emulium® Delta as the emulsifier, and 3.0% of stearyl alcohol as the co-emulsifier. In comparison with the COW cream, the LLC cream significantly increased the skin retention of EA and 4-MSK both in vitro and in vivo. In conclusion, the LLC carrier serves as a promising choice for topical preparation by enhancing skin retention and providing desirable rheological characteristics.

  7. Development and pharmacological evaluation of in vitro nanocarriers composed of lamellar silicates containing copaiba oil-resin for treatment of endometriosis

    Energy Technology Data Exchange (ETDEWEB)

    Almeida Borges, Vinícius Raphael de [Department of Drugs and Pharmaceutics, Faculty of Pharmacy, Federal University of Rio de Janeiro, Rio de Janeiro (Brazil); Henriques da Silva, Julianna [Programa de Pesquisa em Biologia Celular e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro (Brazil); Soares Barbosa, Samantha [Department of Drugs and Pharmaceutics, Faculty of Pharmacy, Federal University of Rio de Janeiro, Rio de Janeiro (Brazil); Nasciutti, Luiz Eurico [Programa de Pesquisa em Biologia Celular e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro (Brazil); Cabral, Lúcio Mendes [Department of Drugs and Pharmaceutics, Faculty of Pharmacy, Federal University of Rio de Janeiro, Rio de Janeiro (Brazil); Pereira de Sousa, Valeria, E-mail: valeria@pharma.ufrj.br [Department of Drugs and Pharmaceutics, Faculty of Pharmacy, Federal University of Rio de Janeiro, Rio de Janeiro (Brazil)

    2016-07-01

    In this work, newly developed nanocomposites based upon lamellar silicates are evaluated to determine their potential in controlling endometriosis. The preparation of the new nanocarriers is detailed, properties characterized and in vitro pharmacological evaluation performed. The nanocomposites in this study were obtained from the reaction of copaiba oil-resin (COPA) with the polymer polyvinylpyrrolidone (PVP K-30). COPA was selected due to its antiinflammatory and anticancer activities along with the organophilic derivatives of sodium montmorillonite, Viscogel B8, S7 and S4. The results indicated that it was feasible to obtain a good yield of a COPA nanocomposite using a simple process. Intercalation was confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). In vitro release experiments demonstrated that COPA was released from the nanocomposite in a delayed fashion. Whereas, in vitro pharmacological studies showed a reduction in viability and proliferation of endometriotic cell cultures upon COPA nanocomposite treatment, suggesting that the system developed here can be a promising alternative therapy for the oral treatment of endometriosis. - Highlights: • Nanocomposite containing copaiba oil-resin can be obtained with good yield by intercalation in solution method. • The copaiba oil-resin is released from the nanocomposite following Higuchi's model in a delayed release. • The nanocomposites containing copaiba reduced the viability and proliferative capacity of the endometriotic cell cultures.

  8. Comparison of iCare tonometer and Goldmann applanation tonometry in normal corneas and in eyes with automated lamellar and penetrating keratoplasty.

    Science.gov (United States)

    Salvetat, M L; Zeppieri, M; Miani, F; Tosoni, C; Parisi, L; Brusini, P

    2011-05-01

    To compare intraocular pressure (IOP) measurements with Goldmann applanation tonometry (GAT) and iCare tonometry in normal and post-keratoplasty corneas and to assess the influence of central corneal thickness (CCT), corneal curvature (CC), and corneal astigmatism (CA) on IOP. This prospective cross-sectional study included one eye of 101 subjects with normal corneas (58 healthy subjects, 43 glaucoma); and 90 post-keratoplasty patients: 34 penetrating keratoplasties (PK); 20 automated-lamellar-therapeutic keratoplasties (ALTK); 19 Descemet-stripping-automated-endothelial keratoplasties (DSAEK); 17 edematous grafts. All subjects underwent GAT and iCare IOP measurements in random order, and CCT, CC, and CA evaluation. The Bland-Altman method and multivariate regression analysis were used to assess inter-tonometer agreement and the influence of CCT, CC, and CA on IOP. iCare significantly underestimated IOP in all groups compared with GAT (GAT minus iCare of 3.5±3.5 mm Hg, Pkeratoplasty eyes, except between CC and iCare measurements for PK eyes. The agreement between GAT and iCare was clinically acceptable in control, ALTK and DSAEK groups, and poor in PK and edematous grafts eyes. In normal corneas, GAT was significantly affected by CCT; iCare was influenced by CCT and CC. The iCare appeared less influenced by corneal edema when compared with GAT. High IOP readings taken with both tonometers in grafts should raise suspicion of true elevated IOP.

  9. Nanopatterning via Self-Assembly of a Lamellar-Forming Polystyrene-block-Poly(dimethylsiloxane Diblock Copolymer on Topographical Substrates Fabricated by Nanoimprint Lithography

    Directory of Open Access Journals (Sweden)

    Dipu Borah

    2018-01-01

    Full Text Available The self-assembly of a lamellar-forming polystyrene-block-poly(dimethylsiloxane (PS-b-PDMS diblock copolymer (DBCP was studied herein for surface nanopatterning. The DBCP was synthesized by sequential living anionic polymerization of styrene and hexamethylcyclotrisiloxane (D3. The number average molecular weight (Mn, polydispersity index (Mw/Mn and PS volume fraction (φps of the DBCP were MnPS = 23.0 kg mol−1, MnPDMS = 15.0 kg mol−1, Mw/Mn = 1.06 and φps = 0.6. Thin films of the DBCP were cast and solvent annealed on topographically patterned polyhedral oligomeric silsesquioxane (POSS substrates. The lamellae repeat distance or pitch (λL and the width of the PDMS features (dL are ~35 nm and ~17 nm, respectively, as determined by SEM. The chemistry of the POSS substrates was tuned, and the effects on the self-assembly of the DBCP noted. The PDMS nanopatterns were used as etching mask in order to transfer the DBCP pattern to underlying silicon substrate by a complex plasma etch process yielding sub-15 nm silicon features.

  10. European core curriculum in neurorehabilitation

    NARCIS (Netherlands)

    Sandrini, G.; Binder, H.; Homberg, V.; Saltuari, L.; Tarkka, I.; Smania, N.; Corradini, C.; Giustini, A.; Katterer, C.; Picari, L.; Diserens, K.; Koenig, E.; Geurts, A.C.; Anghelescu, A.; Opara, J.; Tonin, P.; Kwakkel, G.; Golyk, V.; Onose, G.; Perennou, D.; Picelli, A.

    2017-01-01

    To date, medical education lacks Europe-wide standards on neurorehabilitation. To address this, the European Federation of NeuroRehabilitation Societies (EFNR) here proposes a postgraduate neurorehabilitation training scheme. In particular, the European medical core curriculum in neurorehabilitation

  11. Viral Evolution Core | FNLCR Staging

    Science.gov (United States)

    Brandon F. Keele, Ph.D. PI/Senior Principal Investigator, Retroviral Evolution Section Head, Viral Evolution Core Leidos Biomedical Research, Inc. Frederick National Laboratory for Cancer Research Frederick, MD 21702-1201 Tel: 301-846-173

  12. Nanoporous polymer liquid core waveguides

    DEFF Research Database (Denmark)

    Gopalakrishnan, Nimi; Christiansen, Mads Brøkner; Ndoni, Sokol

    2010-01-01

    We demonstrate liquid core waveguides defined by UV to enable selective water infiltration in nanoporous polymers, creating an effective refractive index shift Δn=0.13. The mode confinement and propagation loss in these waveguides are presented.......We demonstrate liquid core waveguides defined by UV to enable selective water infiltration in nanoporous polymers, creating an effective refractive index shift Δn=0.13. The mode confinement and propagation loss in these waveguides are presented....

  13. Core Benefits of Network Participation

    OpenAIRE

    Kheiri Pileh Roud, Ensieh

    2015-01-01

    This study deals with the core benefits of network participation from the maritime companies’ perspective. It mainly focuses on the area of innovation, network qualities and absorptive capacities. A single case study has been conducted to address two research questions; 1) what are the core benefits of network participation for a maritime company? 2) Which qualities of network events influence the benefits for the participants? The main findings show that, the networks are valuable communi...

  14. Core break-off mechanism

    Science.gov (United States)

    Myrick, Thomas M. (Inventor)

    2003-01-01

    A mechanism for breaking off and retaining a core sample of a drill drilled into a ground substrate has an outer drill tube and an inner core break-off tube sleeved inside the drill tube. The break-off tube breaks off and retains the core sample by a varying geometric relationship of inner and outer diameters with the drill tube. The inside diameter (ID) of the drill tube is offset by a given amount with respect to its outer diameter (OD). Similarly, the outside diameter (OD) of the break-off tube is offset by the same amount with respect to its inner diameter (ID). When the break-off tube and drill tube are in one rotational alignment, the two offsets cancel each other such that the drill can operate the two tubes together in alignment with the drill axis. When the tubes are rotated 180 degrees to another positional alignment, the two offsets add together causing the core sample in the break-off tube to be displaced from the drill axis and applying shear forces to break off the core sample.

  15. Viscosity of Earth's Outer Core

    CERN Document Server

    Smylie, D E

    2007-01-01

    A viscosity profile across the entire fluid outer core is found by interpolating between measured boundary values, using a differential form of the Arrhenius law governing pressure and temperature dependence. The discovery that both the retrograde and prograde free core nutations are in free decay (Palmer and Smylie, 2005) allows direct measures of viscosity at the top of the outer core, while the reduction in the rotational splitting of the two equatorial translational modes of the inner core allows it to be measured at the bottom. We find 2,371 plus/minus 1,530 Pa.s at the top and 1.247 plus/minus 0.035 x 10^11 Pa.s at the bottom. Following Brazhkin (1998) and Brazhkin and Lyapin (2000) who get 10^2 Pa.s at the top, 10^11 Pa.s at the bottom, by an Arrhenius extrapolation of laboratory experiments, we use a differential form of the Arrhenius law to interpolate along the melting temperature curve to find a viscosity profile across the outer core. We find the variation to be closely log-linear between the meas...

  16. X-ray diffraction characterization of the dense phases formed by nucleosome core particles.

    Science.gov (United States)

    Mangenot, Stéphanie; Leforestier, Amélie; Durand, Dominique; Livolant, Françoise

    2003-04-01

    Multiple dense phases of nucleosome core particles (NCPs) were formed in controlled ionic conditions (15-160 mM monovalent salt, no divalent ions), under osmotic pressures ranging from 4.7 x 10(5) to 2.35 x 10(6) Pa. We present here the x-ray diffraction analysis of these phases. In the lamello-columnar phase obtained at low salt concentration (50 mM), NCPs order into either a two-dimensional columnar hexagonal phase or into three-dimensional orthorhombic (quasi-hexagonal) crystals. The lamellar and hexagonal (or quasi-hexagonal) organizations coexist in the intermediate salt range; their demixing requires a long time. For an applied pressure P = 4.7 10(5) Pa, the calculated NCPs concentration ranges from approximately 280 to 320 mg/ml in the lamello-columnar phase to 495 to 585 mg/ml in the three-dimensional orthorhombic phase. These concentrations cover the concentration of the living cell.

  17. Modified deep anterior lamellar keratoplasty for the treatment of advanced keratoconus with steep corneal curvature to help in eliminating the wrinkles in the Descemet′s membrane

    Directory of Open Access Journals (Sweden)

    Hamid Khakshoor

    2014-01-01

    Full Text Available Aims: To determine the clinical efficacy of modified deep anterior lamellar keratoplasty (DALK for the treatment of advanced-stage keratoconus with steep curvature. Materials and Methods: In this interventional, non-comparative case series, 30 patients with advanced stages of keratoconus and curvature of more than 60 D underwent a modified DALK procedure. In this technique, after big-bubble formation, posterior stromal lamella was cut and removed 5 mm centrally (baring Descemet′s membrane completely with posterior stromal layer remaining peripherally. Results: The study included 30 eyes (30 patients with a mean ± SD age of 25 ± 5.4 years. The follow-up examination was performed for all participants up to 12 months after the surgery. The mean uncorrected visual acuity (UCVA increased from 20/800 before the surgery to a subsequent 3/10 (P = 0.12. Likewise, best spectacle corrected visual acuity (BSCVA improved, reaching 6/10 postoperatively (former quantity 20/200 (P = 0.18. In addition, mean keratometry and keratometric astigmatism managed to achieve considerable improvement, from 58.8 ± 5.4 D to 46.5 ± 2.1 D and 7.8 ± 2.1 to 4.54 ± 1.54 D, respectively (P = 0.52. Descemet′s membrane wrinkling was not seen in any patient postoperatively. Conclusions: This technique is effective in restoring acceptable vision and corneal regularity in advanced cases of keratoconus with a curvature more than 60 D who are also at risk of Descemet′s membrane wrinkling after DALK. Therefore, this procedure could prevent from Descemet membrane wrinkling in such cases.

  18. Use of the Ishikawa diagram in a case-control analysis to assess the causes of a diffuse lamellar keratitis outbreak

    Directory of Open Access Journals (Sweden)

    Luis Henrique Lira

    Full Text Available ABSTRACT Purpose: To identify the causes of a diffuse lamellar keratitis (DLK outbreak using a systematic search tool in a case-control analysis. Methods: An Ishikawa diagram was used to guide physicians to determine the potential risk factors involved in this outbreak. Coherence between the occurrences and each possible cause listed in the diagram was verified, and the total number of eyes at risk was used to calculate the proportion of affected eyes. Multivariate analysis was performed using logistic regression to determine the independent effect of the risk factors, after controlling for confounders and test interactions. Results: All DLK cases were reported in 2007 between June 13 and December 21; during this period, 3,698 procedures were performed. Of the 1,682 flap-related procedures, 204 eyes of 141 individuals presented with DLK. No direct relationship was observed between the occurrence of DLK and the presence of any specific factors; however, flap-lifting enhancements, procedures performed during the morning shift, and non-use of therapeutic contact lenses after the surgery were significantly related to higher occurrence percentages of this condition. Conclusions: The Ishikawa diagram, like most quality tools, is a visualization and knowledge organization tool. This systematization allowed the investigators to thoroughly assess all the possible causes of DLK outbreak. A clear view of the entire surgical logistics permitted even more rigid management of the main factors involved in the process and, as a result, highlighted factors that deserved attention. The case-control analysis on every factor raised by the Ishikawa diagram indicated that the commonly suspected factors such as biofilm contamination of the water reservoir in autoclaves, the air-conditioning filter system, glove powder, microkeratome motor oil, and gentian violet markers were not related to the outbreak.

  19. Comparison the post operative refractive errors in same size corneal transplantation through deep lamellar keratoplasty and penetrating keratoplasty methods after sutures removing in keratoconus patients

    Directory of Open Access Journals (Sweden)

    Hasan Razmjoo

    2016-01-01

    Full Text Available Background: Corneal transplantation is a surgery in which cornea is replaced by a donated one and can be completely penetrating keratoplasty (PK or included a part of cornea deep lamellar keratoplasty (DLK. Although the functional results are limited by some complications, it is considered as one of the most successful surgeries. This study aimed to compare the refractive errors after same size corneal transplantation through DLK and PK methods in keratoconus patients over 20 years. Materials and Methods: This descriptive, analytical study was conducted in Feiz Hospital, Sadra and Persian Clinics of Isfahan in 2013–2014. In this study, 35 patients underwent corneal transplantation by PK and 35 patients by DLK, after removing the sutures, the patients were compared in terms of best corrected visual acuity (BCVA and refractive errors. Data were analyzed using Chi-square and t Student tests by SPSS software. Results: The BCVA mean in DLK and PK groups was 6/10 ± 2/10 and 5/10 ± 2/10, respectively, with no significant difference (P = 0.4. The results showed 9 cases of DLK and 6 cases of PK had normal (8/10 ≤ BCVA visual acuity (25.7% vs. 17.1%, 24 cases of DLK and 27 cases of PK had mild vision impairment (68.6% vs. 77.1% and 2 cases of the DLK group and 2 cases of PK had moderate vision impairment, (5.7% vs. 5.7%, there was no significant difference in “BCVA” (P = 0.83. Conclusions: Both methods were acceptably effective in improving BCVA, but according to previous articles (5,9,10 the DLK method due to fewer complications and less risk of rejection was superior to another method and in the absence of any prohibition this method is recommended.

  20. Modified deep anterior lamellar keratoplasty for the treatment of advanced keratoconus with steep corneal curvature to help in eliminating the wrinkles in the Descemet's membrane.

    Science.gov (United States)

    Khakshoor, Hamid; Eslampoor, Alireza; Rad, Saeed Shokoohi; Vejdani, Amirhossein

    2014-04-01

    To determine the clinical efficacy of modified deep anterior lamellar keratoplasty (DALK) for the treatment of advanced-stage keratoconus with steep curvature. In this interventional, non-comparative case series, 30 patients with advanced stages of keratoconus and curvature of more than 60 D underwent a modified DALK procedure. In this technique, after big-bubble formation, posterior stromal lamella was cut and removed 5 mm centrally (baring Descemet's membrane completely) with posterior stromal layer remaining peripherally. The study included 30 eyes (30 patients with a mean ± SD age of 25 ± 5.4 years). The follow-up examination was performed for all participants up to 12 months after the surgery. The mean uncorrected visual acuity (UCVA) increased from 20/800 before the surgery to a subsequent 3/10 (P = 0.12). Likewise, best spectacle corrected visual acuity (BSCVA) improved, reaching 6/10 postoperatively (former quantity 20/200) (P = 0.18). In addition, mean keratometry and keratometric astigmatism managed to achieve considerable improvement, from 58.8 ± 5.4 D to 46.5 ± 2.1 D and 7.8 ± 2.1 to 4.54 ± 1.54 D, respectively (P = 0.52). Descemet's membrane wrinkling was not seen in any patient postoperatively. This technique is effective in restoring acceptable vision and corneal regularity in advanced cases of keratoconus with a curvature more than 60 D who are also at risk of Descemet's membrane wrinkling after DALK. Therefore, this procedure could prevent from Descemet membrane wrinkling in such cases.

  1. Neutron scattering study of a membrane phase miscibility gap: Coexistence of L{sub 3} 'sponge' and L{sub {alpha}} Lamellar phases

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, W A; Porcar, L, E-mail: Hamilton.WA@gmail.com

    2010-11-01

    We report on a small angle neutron scattering (SANS) study of a temperature driven first order phase transition in a 25wt% solution of the surfactant AOT (Sodium Di-2-ethylhexyl Sulfosuccinate) in 1.5wt% heavy brine between an isotropic L{sub 3} 'sponge' state at 27 deg. C and a stacked lamellar L{sub {alpha}} monophase 55 deg. C. The prominent scattering features of these phases are correlation peaks due to the mean passage size of the L{sub 3} sponge and the L{sub {alpha}} stacking separation. This ratio of the monophase peak positions Q{sub {alpha}}/Q{sub 3}{approx}1.3, is consistent with previous observations in this and similar systems. In the present study we tracked this system through the intermediate L{sub 3} +L{sub {alpha}} biphasic miscibility gap. There the initial appearance of the L{sub {alpha}} peak at 33.25 deg. C was at a scattering vector some 23% higher than the final high temperature monophase value. During coexistence both L{sub 3} and L{sub {alpha}} phase peak positions decreased linearly with increasing temperature maintaining a roughly constant ratio Q{sub {alpha}}/Q{sub 3} {approx}1.6-1.7. Two phase fits to the scattering data and application of scaling law predictions allow us to obtain local L{sub 3} phase volume fractions in the biphasic region and make preliminary determinations of the structural accomodations necessitated by phase coexistence in this system's miscibility gap.

  2. SEM/EBSD Analysis on Globularization Behavior of Lamellar Microstructure in Ti-6Al-4V During Hot Deformation and Annealing

    Science.gov (United States)

    Ito, Yoshinori; Murakami, Shogo; Tsuji, Nobuhiro

    2017-09-01

    Scanning electron microscope/electron back-scattering diffraction was used to investigate local misorientation development within an individual α plate of a Ti-6Al-4V alloy with an α lamellar microstructure during hot deformation at 1223 K (950 °C) and a strain rate of 0.1 s-1. The correlation between the local misorientation development and the globularization behavior of α plates during subsequent annealing at 1223 K (950 °C) was discussed. The misorientation profile along an individual α plate showed that not only a continuous and smooth change in orientation but also a discontinuous change in orientation was developed by the hot deformation. We assume that the points where discontinuous change in orientation occurs, P d, became α/ α boundaries and resulted in splitting α plates the annealing. The mean length between adjacent discontinuous points, L I, was determined and compared with the actual mean length of the α plates after hot deformation and subsequent annealing, L a, as measured by optical microscopy. The two kinds of length parameters coincided at lower strains, but significant differences were observed at higher strains, i.e., L I was larger than L a. Further analysis showed that rotation axes (R.A.s) changed even within regions where orientation changes were continuous. By taking into account the points where the R.A.s changed, P r and P d, the mean length between adjacent points, L II, appeared to coincide with L a at higher strains. A higher lattice distortion is expected near points P r at higher strains, which results in the formation of new α/ α boundaries in subsequent annealing. Consequently, points P d already developed by hot deformation were considered to become α/ α boundaries and led to splitting α plates in annealing. New α/ α boundaries formed at points P r in subsequent annealing after a higher strain deformation, which led to a splitting of α plates as well.

  3. Risk factors for donor endothelial loss in eye bank-prepared posterior lamellar corneal tissue for descemet stripping automated endothelial keratoplasty.

    Science.gov (United States)

    Liu, Yu-Chi; Alvarez Paraz, Carisa M; Cajucom-Uy, Howard Yu; Agahari, Djoni; Sethuraman, Selvam; Tan, Donald T-H; Mehta, Jodhbir S

    2014-07-01

    The aim of this study was to investigate donor, tissue, and precut procedure risk factors for endothelial cell density (ECD) loss in posterior lamellar corneal tissue preparation by an eye bank for Descemet stripping automated endothelial keratoplasty. A total of 259 corneoscleral rims precut by the Singapore Eye Bank from October 2011 to August 2013 were evaluated. Donor characteristics, tissue characteristics, and precut procedure parameters were analyzed. The mean donor age was 57.18 ± 11.35 years, and the mean cutting transition time was 4.16 ± 0.75 seconds. The mean ECD was 2826 ± 225 and 2787 ± 224 cells per square millimeter before and after precutting, respectively, with an average ECD change of -1.38% ± 3.28%. The precutting procedure failure rate was 1.2%. Mutivariate regression analysis showed that an older donor age, a higher ECD before cutting, and a slower cutting transition speed were significant factors. Corneas with an ECD >2800 cells per square millimeter before precutting, cutting transition time >5.5 seconds, and corneas with donor age >65 years were significantly more likely to have greater than 5% ECD loss after precutting (odds ratio, 6.42, 1.66, and 1.62; 95% confidence interval, 1.44-29.43, 1.45-2.72, and 1.66-5.82, respectively). Donor source, death-to-preservation time (range, 0.67-10.88 hours), death-to-precutting time (range, 0-7 days), and graft thickness (range, 43-232 μm) were not statistically significant factors. The ECD loss in the precut tissue prepared by the eye bank was very low. The risk factors identified provide better understanding of how to improve the quality and safety profiles when preparing graft tissue for Descemet stripping automated endothelial keratoplasty.

  4. Full MOX core for PWRs

    Energy Technology Data Exchange (ETDEWEB)

    Puill, A.; Aniel-Buchheit, S. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Direction des Reacteurs Nucleaires

    1997-12-31

    Plutonium management is a major problem of the back end of the fuel cycle. Fabrication costs must be reduced and plant operation simplified. The design of a full MOX PWR core would enable the number of reactors devoted to plutonium recycling to be reduced and fuel zoning to be eliminated. This paper is a contribution to the feasibility studies for achieving such a core without fundamental modification of the current design. In view of the differences observed between uranium and plutonium characteristics it seems necessary to reconsider the safety of a MOX-fuelled PWR. Reduction of the control worth and modification of the moderator density coefficient are the main consequences of using MOX fuel in a PWR. The core reactivity change during a draining or a cooling is thus of prime interest. The study of core global draining leads to the following conclusion: only plutonium fuels of very poor quality (i.e. with low fissile content) cannot be used in a 900 MWe PWR because of a positive global voiding reactivity effect. During a cooling accident, like an spurious opening of a secondary-side valve, the hypothetical return to criticality of a 100% MOX core controlled by means of 57 control rod clusters (made of hafnium-clad B{sub 4}C rods with a 90% {sup 10}B content) depends on the isotopic plutonium composition. But safety criteria can be complied with for all isotopic compositions provided the {sup 10}B content of the soluble boron is increased to a value of 40%. Core global draining and cooling accidents do not present any major obstacle to the feasibility of a 100% MOX PWR, only minor hardware modifications will be required. (author)

  5. Ice Core Dating Software for Interactive Dating of Ice Cores

    Science.gov (United States)

    Kurbatov, A. V.; Mayewski, P. A.; Abdul Jawad, B. S.

    2005-12-01

    Scientists involved in ice core dating are well familiar with the problem of identification and recording the depth of annual signals using stable isotopes, glaciochemistry, ECM (electrical conductivity), DEP (dielectric properties) and particle counter data. Traditionally all parameters used for ice core dating were plotted as a function of depth, printed and after years were marked on the paper, converted to depth vs. age time scale. To expedite this tedious and manual process we developed interactive computer software, Ice core Dating (ICD) program. ICD is written in Java programming language, and uses GPL and GPL site licensed graphic libraries. The same 3.5 Mb in size pre-compiled single jar file, that includes all libraries and application code, was successfully tested on WinOS, Mac OSX, Linux, and Solaris operating systems running Java VM version 1.4. We have followed the modular design philosophy in our source code so potential integration with other software modules, data bases and server side distributed computer environments can be easily implemented. We expect to continue development of new suites of tools for easy integration of ice core data with other available time proxies. ICD is thoroughly documented and comes with a technical reference and cookbook that explains the purpose of the software and its many features, and provides examples to help new users quickly become familiar with the operation and philosophy of the software. ICD is available as a free download from the Climate Change Institute web site ( under the terms of GNU GPL public license.

  6. Core physics analysis of 100% MOX core in IRIS

    Energy Technology Data Exchange (ETDEWEB)

    Franceschini, Fausto [Westinghouse Electric Company LLC, Science and Technology Department, Pittsburgh, PA 15235 (United States)], E-mail: FranceF@westinghouse.com; Petrovic, Bojan [Georgia Institute of Technology, Nuclear and Radiological Engineering, G.W. Woodruff School, Atlanta, GA 30332-0405 (United States)

    2008-09-15

    International Reactor Innovative and Secure (IRIS) is an advanced small-to-medium-size (1000 MWt) Pressurized Water Reactor (PWR), targeting deployment around 2015. Its reference core design is based on the current Westinghouse UO{sub 2} fuel with less than 5% {sup 235}U, and the analysis has been previously completed confirming good performance for that case. The full MOX fuel core is currently under evaluation as one of the alternatives for the second wave of IRIS reactors. A full 3-D neutronic analysis has been performed to examine main core performance and safety parameters, such as critical boron concentration, peaking factors, discharge burnup, reactivity coefficients, shut-down margin, etc. In addition, the basis to perform load follow maneuvers via the Westinghouse innovative strategy MSHIM has been established. The enhanced moderation of the IRIS fuel lattice facilitates MOX core design, and all the obtained results are within the operational and safety limits considered thus confirming viability of this option from the reactor physics standpoint.

  7. The myth of core stability.

    Science.gov (United States)

    Lederman, Eyal

    2010-01-01

    The principle of core stability has gained wide acceptance in training for the prevention of injury and as a treatment modality for rehabilitation of various musculoskeletal conditions in particular of the lower back. There has been surprisingly little criticism of this approach up to date. This article re-examines the original findings and the principles of core stability/spinal stabilisation approaches and how well they fare within the wider knowledge of motor control, prevention of injury and rehabilitation of neuromuscular and musculoskeletal systems following injury.

  8. Core-shell nanostructured catalysts.

    Science.gov (United States)

    Zhang, Qiao; Lee, Ilkeun; Joo, Ji Bong; Zaera, Francisco; Yin, Yadong

    2013-08-20

    Novel nanotechnologies have allowed great improvements in the syn-thesis of catalysts with well-controlled size, shape, and surface properties. Transition metal nanostructures with specific sizes and shapes, for instance, have shown great promise as catalysts with high selectivities and relative ease of recycling. Researchers have already demonstrated new selective catalysis with solution-dispersed or supported-metal nanocatalysts, in some cases applied to new types of reactions. Several challenges remain, however, particularly in improving the structural stability of the catalytic active phase. Core-shell nanostructures are nanoparticles encapsulated and protected by an outer shell that isolates the nanoparticles and prevents their migration and coalescence during the catalytic reactions. The synthesis and characterization of effective core-shell catalysts has been at the center of our research efforts and is the focus of this Account. Efficient core-shell catalysts require porous shells that allow free access of chemical species from the outside to the surface of nanocatalysts. For this purpose, we have developed a surface-protected etching process to prepare mesoporous silica and titania shells with controllable porosity. In certain cases, we can tune catalytic reaction rates by adjusting the porosity of the outer shell. We also designed and successfully applied a silica-protected calcination method to prepare crystalline shells with high surface area, using anatase titania as a model system. We achieved a high degree of control over the crystallinity and porosity of the anatase shells, allowing for the systematic optimization of their photocatalytic activity. Core-shell nanostructures also provide a great opportunity for controlling the interaction among the different components in ways that might boost structural stability or catalytic activity. For example, we fabricated a SiO₂/Au/N-doped TiO₂ core-shell photocatalyst with a sandwich structure that showed

  9. Core Task and Organizational Reality

    DEFF Research Database (Denmark)

    Vikkelsø, Signe

    2015-01-01

    of core objects such as ‘task’ and ‘coordination,’ contemporary organization studies emphasize, much like other social science disciplines, broader topics such as ‘network,’ ‘identity,’ and ‘change.’ The paper argues that this altered focus and vocabulary is accompanied by a diminished ability to specify...... and intervene into the practical reality of organizations. It further argues that a discipline's core objects are not anachronisms to be discarded with, but crucial for specifying reality in ways that have proven practically relevant and still are....

  10. Gelcasting Alumina Cores for Investment Casting

    Energy Technology Data Exchange (ETDEWEB)

    Janney, M A; Klug, F J

    2001-01-01

    General Electric currently uses silica investment casting cores for making superalloy turbine blades. The silica core technology does not provide the degree of dimensional control needed for advanced turbine system manufacture. The sum of the various process variables in silica core manufacturing produces cores that have more variability than is allowed for in advanced, power-generation gas turbine airfoils.

  11. Core Stability Training for Injury Prevention

    OpenAIRE

    Huxel Bliven, Kellie C.; Anderson, Barton E.

    2013-01-01

    Context: Enhancing core stability through exercise is common to musculoskeletal injury prevention programs. Definitive evidence demonstrating an association between core instability and injury is lacking; however, multifaceted prevention programs including core stabilization exercises appear to be effective at reducing lower extremity injury rates. Evidence Acquisition: PubMed was searched for epidemiologic, biomechanic, and clinical studies of core stability for injury prevention (keywords: ...

  12. One Health Core Competency Domains

    Directory of Open Access Journals (Sweden)

    Rebekah Frankson

    2016-09-01

    Full Text Available The emergence of complex global challenges at the convergence of human, animal, and environmental health has catalyzed a movement supporting ‘One Health’ approaches. Despite recognition of the importance of One Health approaches to address these complex challenges, little effort has been directed at identifying the seminal knowledge, skills and attitudes necessary for individuals to successfully contribute to One Health efforts. Between 2008 and 2011, three groups independently embarked on separate initiatives to identify core competencies for professionals involved with One Health approaches. Core competencies were considered critically important for guiding curriculum development and continuing professional education as they describe the knowledge, skills and attitudes required to be effective. A workshop was convened in 2012 to synthesize the various strands of work on One Health competencies. Despite having different mandates, participants, and approaches, all of these initiatives identified similar core competency domains: management; communication and informatics; values and ethics; leadership; teams and collaboration; roles and responsibilities; and systems thinking. These core competency domains have been used to develop new continuing professional education programs for One Health professionals and help university curricula prepare new graduates to be able to contribute more effectively to One Health approaches.

  13. Stability of Molten Core Materials

    Energy Technology Data Exchange (ETDEWEB)

    Layne Pincock; Wendell Hintze

    2013-01-01

    The purpose of this report is to document a literature and data search for data and information pertaining to the stability of nuclear reactor molten core materials. This includes data and analysis from TMI-2 fuel and INL’s LOFT (Loss of Fluid Test) reactor project and other sources.

  14. Core shift effect in blazars

    Science.gov (United States)

    Agarwal, A.; Mohan, P.; Gupta, Alok C.; Mangalam, A.; Volvach, A. E.; Aller, M. F.; Aller, H. D.; Gu, M. F.; Lähteenmäki, A.; Tornikoski, M.; Volvach, L. N.

    2017-07-01

    We studied the pc-scale core shift effect using radio light curves for three blazars, S5 0716+714, 3C 279 and BL Lacertae, which were monitored at five frequencies (ν) between 4.8 and 36.8 GHz using the University of Michigan Radio Astronomical Observatory (UMRAO), the Crimean Astrophysical Observatory (CrAO) and Metsähovi Radio Observatory for over 40 yr. Flares were Gaussian fitted to derive time delays between observed frequencies for each flare (Δt), peak amplitude (A) and their half width. Using A ∝ να, we infer α in the range of -16.67-2.41 and using Δ t ∝ ν ^{1/k_r}, we infer kr ∼ 1, employed in the context of equipartition between magnetic and kinetic energy density for parameter estimation. From the estimated core position offset (Ωrν) and the core radius (rcore), we infer that opacity model may not be valid in all cases. The mean magnetic field strengths at 1 pc (B1) and at the core (Bcore) are in agreement with previous estimates. We apply the magnetically arrested disc model to estimate black hole spins in the range of 0.15-0.9 for these blazars, indicating that the model is consistent with expected accretion mode in such sources. The power-law-shaped power spectral density has slopes -1.3 to -2.3 and is interpreted in terms of multiple shocks or magnetic instabilities.

  15. Fuzzy Cores and Fuzzy Balancedness

    NARCIS (Netherlands)

    van Gulick, G.; Norde, H.W.

    2011-01-01

    We study the relation between the fuzzy core and balancedness for fuzzy games. For regular games, this relation has been studied by Bondareva (1963) and Shapley (1967). First, we gain insight in this relation when we analyse situations where the fuzzy game is continuous. Our main result shows that

  16. Fuzzy cores and fuzzy balancedness

    NARCIS (Netherlands)

    van Gulick, G.; Norde, H.W.

    2013-01-01

    We study the relation between the fuzzy core and balancedness for fuzzy games. For regular games, this relation has been studied by Bondareva (Problemy Kibernet 10:119–139, 1963) and Shapley (Naval Res Logist Q 14: 453–460, 1967). First, we gain insight in this relation when we analyse situations

  17. Common Core: Fact vs. Fiction

    Science.gov (United States)

    Greene, Kim

    2012-01-01

    Despite students' interest in informational text, it has played second fiddle in literacy instruction for years. Now, though, nonfiction is getting its turn in the spotlight. The Common Core State Standards require that students become thoughtful consumers of complex, informative texts--taking them beyond the realm of dry textbooks and…

  18. Epistemology and ontology in core ontologies: FOLaw and LRI-Core, two core ontologies for law

    OpenAIRE

    Breukers, J.A.P.J.; Hoekstra, R.J.

    2004-01-01

    For more than a decade constructing ontologies for legal domains, we, at the Leibniz Center for Law, felt really the need to develop a core ontology for law that would enable us to re-use the common denominator of the various legal domains. In this paper we present two core ontologies for law. The first one was the result of a PhD thesis by [Valente, 1995], called FOLaw. FOLaw speci- fies functional dependencies between types of knowledge involved in legal reasoning. Despite the fact that FOL...

  19. Sialidosis type I carrying V217M/G243R mutations in lysosomal sialidase: an autopsy study demonstrating terminal sialic acid in lysosomal lamellar inclusions and cerebellar dysplasia.

    Science.gov (United States)

    Uchihara, Toshiki; Ohashi, Ken-ichi; Kitagawa, Masanobu; Kurata, Morito; Nakamura, Ayako; Hirokawa, Katsuiku; Kasuga, Tsutomu; Kobayashi, Takayoshi

    2010-01-01

    Autopsy findings of a patient, with sialidosis type I phenotype carrying V217M/G243R mutations in the lysosomal sialidase gene and biochemically defined isolated sialidase deficiency, who died of intractable lymphoma at the age of 32 years, are described. Perikaryal expansion of cytoplasm was evident, mostly in motor neurons (in the anterior horn and the brain stem), dorsal root ganglia, cerebellar dentate neurons and some neurons in the thalamus and nucleus basalis of Meynert. The stored material was lamellar in lysosomes and exhibited a specific affinity to wheat germ agglutinin at light and electron microscopy, which indicates the accumulation of terminal sialic acid at the non-reducing end of the sugar chain in this pathological structure. Neuronal loss in these nuclei, however, was not frequent in spite of frequent and massive cytoplasmic expansion. Neocortex exhibited a mild spongiosis with some swelling of neurons, which contained lipofuscin-like granules and small amount of lamellar structures in lysosomes. This contrast suggests a discrepancy between the storage process and vulnerability of neurons, both variable according to areas examined. In the cerebellar vermis, dysplastic features, such as abnormal layering of Purkinje cells, thinning and rarefaction of the granule cell layer, incomplete formation of synapse and disordered proliferation of Bergmann's glia, were focally accentuated, suggesting some developmental abnormality not secondary to the storage process. This is the first autopsy demonstration of sialic acid in the lamellar materials and of a developmental abnormality in isolated sialidase deficiency. Additional studies are needed to clarify how this molecular abnormality leads to these morphological and clinical manifestations.

  20. Cores to the rescue: how old cores enable new science

    Science.gov (United States)

    Ito, E.; Noren, A. J.; Brady, K.

    2016-12-01

    The value of archiving scientific specimens and collections for the purpose of enabling further research using new analytical techniques, resolving conflicting results, or repurposing them for entirely new research, is often discussed in abstract terms. We all agree that samples with adequate metadata ought to be archived systematically for easy access, for a long time and stored under optimal conditions. And yet, as storage space fills, there is a temptation to cull the collection, or when a researcher retires, to discard the collection unless the researcher manages to make his or her own arrangement for the collection to be accessioned elsewhere. Nobody has done anything with these samples in over 20 years! Who would want them? It turns out that plenty of us do want them, if we know how to find them and if they have sufficient metadata to assess past work and suitability for new analyses. The LacCore collection holds over 33 km of core from >6700 sites in diverse geographic locations worldwide with samples collected as early as 1950s. From these materials, there are many examples to illustrate the scientific value of archiving geologic samples. One example that benefitted Ito personally were cores from Lakes Mirabad and Zeribar, Iran, acquired in 1963 by Herb Wright and his associates. Several doctoral and postdoctoral students generated and published paleoecological reconstructions based on cladocerans, diatoms, pollen or plant macrofossils, mostly between 1963 and 1967. The cores were resampled in 1990s by a student being jointly advised by Wright and Ito for oxygen isotope analysis of endogenic calcite. The results were profitably compared with pollen and the results published in 2001 and 2006. From 1979 until very recently, visiting Iran for fieldwork was not pallowed for US scientists. Other examples will be given to further illustrate the power of archived samples to advance science.

  1. Separated core turbofan engine; Core bunrigata turbofan engine

    Energy Technology Data Exchange (ETDEWEB)

    Saito, Y.; Endo, M.; Matsuda, Y.; Sugiyama, N.; Sugahara, N.; Yamamoto, K. [National Aerospace Laboratory, Tokyo (Japan)

    1996-04-01

    This report outlines the separated core turbofan engine. This engine is featured by parallel separated arrangement of a fan and core engine which are integrated into one unit in the conventional turbofan engine. In general, cruising efficiency improvement and noise reduction are achieved by low fan pressure ratio and low exhaust speed due to high bypass ratio, however, it causes various problems such as large fan and nacelle weight due to large air flow rate of a fan, and shift of an operating point affected by flight speed. The parallel separated arrangement is thus adopted. The stable operation of a fan and core engine is easily retained by independently operating air inlet unaffected by fan. The large degree of freedom of combustion control is also obtained by independent combustor. Fast response, simple structure and optimum aerodynamic design are easily achieved. This arrangement is also featured by flexibility of development and easy maintenance, and by various merits superior to conventional turbofan engines. It has no technological problems difficult to be overcome, and is also suitable for high-speed VTOL transport aircraft. 4 refs., 5 figs.

  2. Espaço de cores

    Directory of Open Access Journals (Sweden)

    Claudia Feitosa-Santana

    2006-01-01

    Full Text Available O artigo apresenta definições para os termos espaço de cores e sistemas de cores; classifica, de acordo com David Brainard (2003, os sistemas de cores em dois grupos: aparência de cores e diferenças de cores. Dentre os diversos sistemas de cores existentes, o artigo descreve dois deles: o sistema de cores Munsell &– um dos mais utilizados entre os sistemas de aparência de cores &– e a descrição do sistema de cores CIE 1931 &– um dos mais utilizados dentre os sistemas de diferença de cores. Faz-se uma retrospectiva histórica da busca por espaços de cores que representem a percepção de cores humana assim como as diversas reconstruções de espaços de cores por métodos eletrofisiológicos ou psicofísicos. Muitas dessas reconstruções utilizam a escala multidimensional (mds. O artigo também introduz a possibilidade da reconstrução dos espaços de cores de pacientes com discromatopsia adquirida como uma distorção do espaço de indivíduos tricromatas normais.

  3. Conceptual study of advanced PWR core design

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Jin; Chang, Moon Hee; Kim, Keung Ku; Joo, Hyung Kuk; Kim, Young Il; Noh, Jae Man; Hwang, Dae Hyun; Kim, Taek Kyum; Yoo, Yon Jong

    1997-09-01

    The purpose of this project is for developing and verifying the core design concepts with enhanced safety and economy, and associated methodologies for core analyses. From the study of the sate-of-art of foreign advanced reactor cores, we developed core concepts such as soluble boron free, high convertible and enhanced safety core loaded semi-tight lattice hexagonal fuel assemblies. To analyze this hexagonal core, we have developed and verified some neutronic and T/H analysis methodologies. HELIOS code was adopted as the assembly code and HEXFEM code was developed for hexagonal core analysis. Based on experimental data in hexagonal lattices and the COBRA-IV-I code, we developed a thermal-hydraulic analysis code for hexagonal lattices. Using the core analysis code systems developed in this project, we designed a 600 MWe core and studied the feasibility of the core concepts. Two additional scopes were performed in this project : study on the operational strategies of soluble boron free core and conceptual design of large scale passive core. By using the axial BP zoning concept and suitable design of control rods, this project showed that it was possible to design a soluble boron free core in 600 MWe PWR. The results of large scale core design showed that passive concepts and daily load follow operation could be practiced. (author). 15 refs., 52 tabs., 101 figs.

  4. Whole Core Transport Calculation Methodology for a Hexagonal Core

    Energy Technology Data Exchange (ETDEWEB)

    Cho, J. Y.; Kim, K. S.; Lee, C. C.; Zee, S. Q.; Joo, H. G

    2007-07-15

    This report discusses the hexagonal module implemented to the DeCART code and the performance of them. The implemented hexagonal module includes the hexagonal ray tracing and the CMFD acceleration modules. The performance of the implemented hexagonal module is examined for 4 tests of: (1) CMFD acceleration test, (2) the accuracy test of the hexagonal module, (3) the performance test for 2-D NGNP problem and (4) the applicability test for 3-D NGNP problem. The features of the implemented hexagonal modules are: (1) The Modular ray tracing scheme based on a hexagonal assembly and a path linking scheme between the modular rays. (2) Segment generation based on the structure unit. (3) Cell ray approximation: This feature is developed to reduce the memory required to store the segment information. (4) Modified cycle ray scheme that begins the ray tracing at a given surface and finishes if the reflected ray meets the starting surface. This feature is developed to reduce the memory required for the angular flux at the core boundary. (5) Fixed assembly geometry. The pin geometry of the single pin per assembly problem is different from that of the multi-pin problem. The core geometry of a single assembly problem is also different from that of the multi-assembly problem. (6) CMFD module based on unstructured cell. This feature is to deal with the irregular gap cells that are positioned at the assembly boundaries. The examination results of the 4 tests can be summarized as: (1) The CMFD acceleration test shows that the CMFD module speedups about greater than 200 for the core problem. (2) The accuracy test shows that the hexagonal MOC module produces an accurate solution of less than 60 pcm of eigenvalue and less than 2 % of local pin power errors. (3) The performance test for 2-D NGNP problem shows that the implemented hexagonal module works soundly and produces a reasonable solution by cooperating with the existing DeCART library and the other modules. (4) The applicability

  5. Long-term comparison of full-bed deep lamellar keratoplasty with penetrating keratoplasty in treating corneal leucoma caused by herpes simplex keratitis.

    Science.gov (United States)

    Wu, Shuang-Qing; Zhou, Ping; Zhang, Bei; Qiu, Wen-Ya; Yao, Yu-Feng

    2012-02-01

    To compare long-term outcomes of full-bed deep lamellar keratoplasty (DLK) with penetrating keratoplasty (PK) for treating corneal leucoma caused by herpes simplex keratitis (HSK). Retrospective, comparative, interventional case series. setting: Institutional. patients: Inclusion criteria were patients with corneal scarring induced exclusively by HSK who underwent primary graft of full-bed DLK or PK and completed a minimum of 12 months postoperative follow-up. There was no significant difference of corneal scarring and vascularization between the 2 groups before surgery. Choosing PK or full-bed DLK depended on the patient's own willingness, except those patients with a preoperative endothelial cell count of less than 700 cells/mm(2) or whose endothelial cell count was undetectable were encouraged to undergo only PK. Exclusion criteria were patients with a past history of corneal perforation, nonprimary graft, non-HSK-related corneal scars, and failure to complete a minimum of 12 months of postoperative follow-up. Fifty-eight eyes of 58 patients in the full-bed DLK group and 63 eyes of 63 patients in the PK group met the inclusion criteria. main outcome measures: Postoperative managements, recurrence of HSK, graft rejection, graft survival rate, visual acuity, and corneal endothelial density. The mean postoperative follow-up duration was 45.8 ± 30.9 months in the full-bed DLK group and 47.9 ± 27.2 months in the PK group (P = .70). As compared with the PK group, the full-bed DLK group experienced earlier suture removal (P = .01), needed fewer postoperative visits (P Corneal endothelial cell density was stable from 1 month through 5 years in the full-bed DLK group, but 51.3% cell loss was found in the PK group at 5 years after surgery. At the last visit, 66.1% of eyes with full-bed DLK grafts and 50.9% of eyes with PK grafts achieved a best-correct visual acuity of 0.5 or better (P = .10). Advantages of full-bed DLK over PK are no allograft rejection, longer graft

  6. Lamellar crystalline self-assembly behaviour and solid lipid nanoparticles of a palmityl prodrug analogue of Capecitabine—A chemotherapy agent

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Xiaojuan; Moghaddam, Minoo J.; Sagnella, Sharon M.; Conn, Charlotte E.; Danon, Stephen J.; Waddington, Lynne J.; Drummond, Calum J. [CSIRO/MSE

    2014-09-24

    An amphiphile prodrug, 5'-deoxy-5-fluoro-N4-(palmityloxycarbonyl) cytidine or 5'-deoxy-5-fluoro-N4-(hexadecanaloxycarbonyl) cytidine (5-FCPal), consisting of the same head group as the commercially available chemotherapeutic agent Capecitabine, linked to a palmityl hydrocarbon chain via a carbamate bond is reported. Thermal analysis of this prodrug indicates that it melts at ~115 °C followed quickly by degradation beginning at ~120 °C. The neat solid 5-FCPal amphiphile acquires a lamellar crystalline arrangement with a d-spacing of 28.6 ± 0.3 Å, indicating interdigitation of the hydrocarbon chains. Under aqueous conditions, solid 5-FCPal is non-swelling and no lyotropic liquid crystalline phase formation is observed. In order to assess the in vitro toxicity and in vivo efficacy in colloidal form, solid lipid nanoparticles (SLNs) with an average size of ~700 nm were produced via high pressure homogenization. The in vitro toxicity of the 5-FCPal SLNs against several different cancer and normal cell types was assessed over a 48 h period, and IC50 values were comparable to those observed for Capecitabine. The in vivo efficacy of the 5-FCPal SLNs was then assessed against the highly aggressive mouse 4T1 breast cancer model. To do so, the prodrug SLNs were administered orally at 3 different dosages (0.1, 0.25, 0.5 mmol/mouse/day) and compared to Capecitabine delivered at the same dosages. After 21 days of receiving the treatments, the 0.5 mmol dose of 5-FCPal exhibited the smallest average tumour volume. Since 5-FCPal is activated in a similar manner to Capecitabine via a 3 step enzymatic pathway with the final step occurring preferentially at the tumour site, formulation of the prodrug into SLNs combines the advantage of selective, localized activation with the sustained release properties of nanostructured amphiphile self-assembly and multiple payload materials thereby potentially creating a more effective anticancer agent.

  7. [Scanning electron microscopic investigations of cutting edge quality in lamellar keratotomy using the Wavelight femtosecond laser (FS-200) : What influence do spot distance and an additional tunnel have?

    Science.gov (United States)

    Hammer, T; Höche, T; Heichel, J

    2018-01-01

    Femtosecond lasers (fs-lasers) are established cutting instruments for the creation of LASIK flaps. Previous studies often showed even rougher surfaces after application of fs-laser systems compared to lamellar keratotomy with mechanical microkeratomes. When cutting the cornea with fs-lasers, an intrastromal gas development occurs, which has a potentially negative influence on the cutting quality if the gas cannot be dissipated; therefore, manufacturers have chosen the way of gas assimilation in so-called pockets. The investigated system creates a tunnel which opens under the conjunctiva. The aim of this study was to investigate the effects of a tunnel as well as the influence of different spot distances on the quality of cut surfaces and edges. In this experimental study on freshly enucleated porcine eyes (n = 15), the following cuts were carried out with the FS-200 (Wavelight, Erlangen, Germany): 1. standard setting (spot and line separation 8 µm), 2. with tunnel for gas drainage, 3. without gas-conducting tunnel, 4. with increased spot spacing (spot and line separation 9 μm instead of 8 μm) and 5. with reduced spot spacing (spot and line separation 7 μm instead of 8 μm). Subsequently, scanning electron microscopy (FEI Quanta 650, Hillsboro, OR) of the cut edges and surfaces as well as the gas drain tunnel were performed. The evaluation was based on an established score. The current fs-laser system (200 Hz) is able to create smooth cutting surfaces and sharp edges. The changed density of laser pulses compared to the standard settings with a reduced or increased distance between the pulses, did not achieve any further improvement in the surface quality. The gas-conducting tunnel could be detected by scanning electron microscope. In the case of cutting without a tunnel, roughened surfaces and irregularities on the cutting edges were found. When the FS-200 fs-laser is used, LASIK cuts with very smooth cut surfaces and sharp cutting

  8. Continuous Chemistry in Ice Cores

    DEFF Research Database (Denmark)

    Kjær, Helle Astrid

    corrections. Further the method successfully identified volcanic eruptions as well as the underlying anthropogenic signal related to the industrial pollution peaking in the 1970’s. The pH method was also applied on the Antarctic RICE ice core and proved useful, contrary to both the ECM and melt water......Ice cores provide high resolution records of past climate and environment. In recent years the use of continuous flow analysis (CFA) systems has increased the measurement throughput, while simultaneously decreasing the risk of contaminating the ice samples. CFA measurements of high temporal...... for the continuous determination of dissolved reactive phosphorus (DRP) by means of a reaction with molybdenum blue. The concentration of DRP in polar ice is low and thus the method relies on enhancing the limit of detection by increasing the absorption length by means of a 2.5 metre LiquidWaveguide Capillary Cell...

  9. Early Evolution of Prestellar Cores

    Science.gov (United States)

    Horedt, G. P.

    2013-08-01

    Prestellar cores are approximated by singular polytropic spheres. Their early evolution is studied analytically with a Bondi-like scheme. The considered approximation is meaningful for polytropic exponents γ between 0 and 6/5, implying radial power-law density profiles between r -1 and r -2.5. Gravitationally unstable Jeans and Bonnor-Ebert masses differ at most by a factor of 3.25. Tidally stable prestellar cores must have a mean density contrast >~ 8 with respect to the external parent cloud medium. The mass-accretion rate relates to the cube of equivalent sound speed, as in Shu's seminal paper. The prestellar masses accreted over 105 years cover the whole stellar mass spectrum; they are derived in simple closed form, depending only on the polytropic equation of state. The stellar masses that can be formed via strict conservation of angular momentum are at most of the order of a brown dwarf.

  10. Accelerator driven sub-critical core

    Science.gov (United States)

    McIntyre, Peter M; Sattarov, Akhdiyor

    2015-03-17

    Systems and methods for operating an accelerator driven sub-critical core. In one embodiment, a fission power generator includes a sub-critical core and a plurality of proton beam generators. Each of the proton beam generators is configured to concurrently provide a proton beam into a different area of the sub-critical core. Each proton beam scatters neutrons within the sub-critical core. The plurality of proton beam generators provides aggregate power to the sub-critical core, via the proton beams, to scatter neutrons sufficient to initiate fission in the sub-critical core.

  11. Divergent Chemoenzymatic Synthesis of Asymmetrical-Core-Fucosylated and Core-Unmodified N-Glycans

    NARCIS (Netherlands)

    Li, Tiehai; Huang, Min; Liu, Lin; Wang, Shuo; Moremen, Kelley W; Boons, Geert-Jan|info:eu-repo/dai/nl/088245489

    2016-01-01

    A divergent chemoenzymaytic approach for the preparation of core-fucosylated and core-unmodified asymmetrical N-glycans from a common advances precursor is described. An undecasaccharide was synthesized by sequential chemical glycosylations of an orthogonally protected core fucosylated

  12. Superconducting Vortex with Antiferromagnetic Core

    Energy Technology Data Exchange (ETDEWEB)

    Arovas, D.P. [Department of Physics, University of California at San Diego, La Jolla, California 92093 (United States); Berlinsky, A.J.; Kallin, C.; Zhang, S. [Department of Physics, Stanford University, Stanford, California 94305 (United States)

    1997-10-01

    We show that a superconducting vortex in underdoped high T{sub c} superconductors could have an antiferromagnetic core. This type of vortex configuration arises as a topological solution in the recently constructed SO(5) nonlinear {sigma} model and in Landau-Ginzburg theory with competing antiferromagnetic and superconducting order parameters. Experimental detection of this type of vortex by muon spin resonance and neutron scattering is proposed. {copyright} {ital 1997} {ital The American Physical Society}

  13. Core curriculum illustration: rib fractures.

    Science.gov (United States)

    Dunham, Gregor M; Perez-Girbes, Alexandre; Linnau, Ken F

    2017-06-01

    This is the 24th installment of a series that will highlight one case per publication issue from the bank of cases available online as part of the American Society of Emergency Radiology (ASER) educational resources. Our goal is to generate more interest in and use of our online materials. To view more cases online, please visit the ASER Core Curriculum and Recommendations for Study online at http://www.aseronline.org/curriculum/toc.htm .

  14. Core curriculum illustration: epiploic appendagitis.

    Science.gov (United States)

    Perez-Girbes, Alexandre; Alegre, Alberto; Linnau, Ken F

    2017-10-12

    This is the 45th installment of a series that will highlight one case per publication issue from the bank of cases available online as part of the American Society of Emergency Radiology (ASER) educational resources. Our goal is to generate more interest in and use of our online materials. To view more cases online, please visit the ASER Core Curriculum and Recommendations for Study online at: http://www.erad.org/page/CCIP_TOC .

  15. Core curriculum illustration: pulmonary laceration.

    Science.gov (United States)

    Carson, Daniel; Edwards, Rachael

    2017-09-05

    This is the 44th installment of a series that will highlight one case per publication issue from the bank of cases available online as part of the American Society of Emergency Radiology (ASER) educational resources. Our goal is to generate more interest in and use of our online materials. To view more cases online, please visit the ASER Core Curriculum and Recommendations for Study online at: http://www.erad.org/page/CCIP_TOC .

  16. Rich-cores in networks

    CERN Document Server

    Ma, Athen

    2014-01-01

    A core is said to be a group of central and densely connected nodes which governs the overall behavior of a network. Profiling this meso--scale structure currently relies on a limited number of methods which are often complex, and have scalability issues when dealing with very large networks. As a result, we are yet to fully understand its impact on network properties and dynamics. Here we introduce a simple method to profile this structure by combining the concepts of core/periphery and rich-club. The key challenge in addressing such association of the two concepts is to establish a way to define the membership of the core. The notion of a "rich-club" describes nodes which are essentially the hub of a network, as they play a dominating role in structural and functional properties. Interestingly, the definition of a rich-club naturally emphasizes high degree nodes and divides a network into two subgroups. Our approach theoretically couples the underlying principle of a rich-club with the escape time of a rand...

  17. Coring in deep hardrock formations

    Energy Technology Data Exchange (ETDEWEB)

    Drumheller, D.S.

    1988-08-01

    The United States Department of Energy is involved in a variety of scientific and engineering feasibility studies requiring extensive drilling in hard crystalline rock. In many cases well depths extend from 6000 to 20,000 feet in high-temperature, granitic formations. Examples of such projects are the Hot Dry Rock well system at Fenton Hill, New Mexico and the planned exploratory magma well near Mammoth Lakes, California. In addition to these programs, there is also continuing interest in supporting programs to reduce drilling costs associated with the production of geothermal energy from underground sources such as the Geysers area near San Francisco, California. The overall progression in these efforts is to drill deeper holes in higher temperature, harder formations. In conjunction with this trend is a desire to improve the capability to recover geological information. Spot coring and continuous coring are important elements in this effort. It is the purpose of this report to examine the current methods used to obtain core from deep wells and to suggest projects which will improve existing capabilities. 28 refs., 8 figs., 2 tabs.

  18. Genetics Home Reference: lamellar ichthyosis

    Science.gov (United States)

    ... Fischer J, Fleckman P, Gina M, Harper J, Hashimoto T, Hausser I, Hennies HC, Hohl D, Hovnanian ... Fischer J, Fleckman P, Gina M, Harper J, Hashimoto T, Hausser I, Hennies HC, Hohl D, Hovnanian ...

  19. Core stability training for injury prevention.

    Science.gov (United States)

    Huxel Bliven, Kellie C; Anderson, Barton E

    2013-11-01

    Enhancing core stability through exercise is common to musculoskeletal injury prevention programs. Definitive evidence demonstrating an association between core instability and injury is lacking; however, multifaceted prevention programs including core stabilization exercises appear to be effective at reducing lower extremity injury rates. PUBMED WAS SEARCHED FOR EPIDEMIOLOGIC, BIOMECHANIC, AND CLINICAL STUDIES OF CORE STABILITY FOR INJURY PREVENTION (KEYWORDS: "core OR trunk" AND "training OR prevention OR exercise OR rehabilitation" AND "risk OR prevalence") published between January 1980 and October 2012. Articles with relevance to core stability risk factors, assessment, and training were reviewed. Relevant sources from articles were also retrieved and reviewed. Stabilizer, mobilizer, and load transfer core muscles assist in understanding injury risk, assessing core muscle function, and developing injury prevention programs. Moderate evidence of alterations in core muscle recruitment and injury risk exists. Assessment tools to identify deficits in volitional muscle contraction, isometric muscle endurance, stabilization, and movement patterns are available. Exercise programs to improve core stability should focus on muscle activation, neuromuscular control, static stabilization, and dynamic stability. Core stabilization relies on instantaneous integration among passive, active, and neural control subsystems. Core muscles are often categorized functionally on the basis of stabilizing or mobilizing roles. Neuromuscular control is critical in coordinating this complex system for dynamic stabilization. Comprehensive assessment and training require a multifaceted approach to address core muscle strength, endurance, and recruitment requirements for functional demands associated with daily activities, exercise, and sport.

  20. CORE SHAPES AND ORIENTATIONS OF CORE-SÉRSIC GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Dullo, Bililign T.; Graham, Alister W., E-mail: Bdullo@astro.swin.edu.au [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, Victoria 3122 (Australia)

    2015-01-01

    The inner and outer shapes and orientations of core-Sérsic galaxies may hold important clues to their formation and evolution. We have therefore measured the central and outer ellipticities and position angles for a sample of 24 core-Sérsic galaxies using archival Hubble Space Telescope (HST) images and data. By selecting galaxies with core-Sérsic break radii R{sub b} —a measure of the size of their partially depleted core—that are ≳ 0.''2, we find that the ellipticities and position angles are quite robust against HST seeing. For the bulk of the galaxies, there is a good agreement between the ellipticities and position angles at the break radii and the average outer ellipticities and position angles determined over R {sub e}/2 < R < R {sub e}, where R {sub e} is the spheroids' effective half light radius. However there are some interesting differences. We find a median ''inner'' ellipticity at R{sub b} of ε{sub med} = 0.13 ± 0.01, rounder than the median ellipticity of the ''outer'' regions ε{sub med} = 0.20 ± 0.01, which is thought to reflect the influence of the central supermassive black hole at small radii. In addition, for the first time we find a trend, albeit weak (2σ significance), such that galaxies with larger (stellar deficit-to-supermassive black hole) mass ratios—thought to be a measure of the number of major dry merger events—tend to have rounder inner and outer isophotes, suggesting a connection between the galaxy shapes and their merger histories. We show that this finding is not simply reflecting the well known result that more luminous galaxies are rounder, but it is no doubt related.

  1. High Efficiency Solar Furnace Core Project

    Data.gov (United States)

    National Aeronautics and Space Administration — It is proposed to develop a high efficiency solar furnace core that greatly lessens the heat losses from the furnace core, either greatly reducing the amount of...

  2. BWR MOX core monitoring at Kernkraftwerk Gundremmingen

    Energy Technology Data Exchange (ETDEWEB)

    Noel, Alejandro [Studsvik Scandpower (Suisse) GmbH, Nussbaumen AG (Switzerland); Holzer, Robert [NIS Ingenieurgesellschaft GmbH, Alzenau (Germany); Anton, Gerd [Studsvik Scandpower GmbH, Norderstedt (Germany); Smith, Kord [Studsvik Scandpower Inc., Idaho Falls (United States)

    2008-07-01

    The replacement of the core monitoring system for twin KWU Boiling Water Reactors (BWR) is presented. The reactors, Kernkraftwerk Gundremmingen B and C (KGG), are located in Germany. Core monitoring for KGG is more challenging than for most BWR reactors due to its core composition with about 30% MOX fuel assemblies. The objectives of this paper are to discuss the specific MOX modelling aspects in CASMO-4/Simulate-3, the impact of the MOX fuel on several core monitoring aspects like the LPRM detector modelling and to present some core monitoring results since the beginning of GARDEL's operation. The available core monitoring results confirm the accuracy of the underlying physical methods. The core monitoring system replacement att KGG was a common project of Studsvik Scandpower and NIS Ingenieurgesellschaft GmbH, where Studsvik Scandpower supplied its standard core monitoring system GARDEL and NIS was responsible for the computer hardware, system integration and plant specific add-ons. (authors)

  3. Optimized Cellular Core for Rotorcraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Patz Materials and Technologies has developed, produced and tested, as part of the Phase-I SBIR, a new form of composite cellular core material, named Interply Core,...

  4. Structure evolution of the LiMnO{sub 2} lamellar oxide during electrochemical cycling; Evolution structurale de l`oxyde lamellaire LiMnO{sub 2} lors du cyclage electrochimique

    Energy Technology Data Exchange (ETDEWEB)

    Delmas, C. [Centre National de la Recherche Scientifique (CNRS), 33 - Pessac (France). Institut de Chimie de la Matiere Condensee de Bordeaux; Capitaine, F.; Majastre [Bollore Technologies, 29 - Quimper (France); Baudry, P. [Electricite de France, 77 - Moret sur Loing (France). Direction des Etudes et Recherches

    1996-12-31

    The LiMnO{sub 2} lamellar oxide, obtained by exchange reaction from its sodium homologue {alpha}-NaMnO{sub 2}, has been used as a positive electrode for lithium batteries. After the first electrochemical cycle, the shape of the potential-composition curve changes and indicates a change in the structure. This modification changes imperceptibly at each cycle and after about 40 cycles, a stationary state is reached. Powder spectra refinement using the Rietvelt method shows a migration of manganese ions from the thin sheets towards the inter-sheet space. After a single cycle, 8% of the manganese ions are already present in the lithium site and this rate reaches 13% after 3 cycles. During long cycling, a redistribution of ions and vacancies inside the cfc oxygenated pile leads to a structure very similar to the LiMn{sub 2}O{sub 4} spinel. This structure evolution is to be compared with the one obtained from the orthorhombic variety of LiMnO{sub 2} but the modification is more progressive with lamellar LiMnO{sub 2}. Abstract only. (J.S.)

  5. Lamellar grains distribution and plastic strain heterogeneities in TiAl cast samples. Experiments and modelling; Distribution des grains lamellaires et heterogeneite de deformation plastique dans des alliages de fonderie a base TiAl. Experiences et modelisation

    Energy Technology Data Exchange (ETDEWEB)

    Gelebart, L. [CEA Saclay, Service de Recherche en Metallurgie Appliquee, 91 - Gif-sur-Yvette (France); Bornert, M.; Bretheau, T.; Caldemaison, D.; Crepin, J.; Zaoui, A. [Ecole Polytechnique, Laboratoire de Mecanique des Solides, UMR CNRS 7649, 91 - Palaiseau (France)

    2004-07-01

    During the cooling of TiAl cast alloys, the distribution of the dual-phase lamellar grains [Ti{sub 3}Al ({alpha}{sub 2}) + TiAl ({gamma})] generates a so-called 'macrostructure'. Because of the highly anisotropic plastic behaviour of the lamellar grains, the distribution of the plastic strain is strongly influenced by such a macrostructure. This heterogeneity is clearly observed by means of a strain-field measurement technique applied to a compression test performed on a cast sample having a 'radial' macrostructure. As a result, a sample having such a macrostructure is not representative of the material and can not be used directly to evaluate 'material parameters'. Moreover the mechanical simulations of cast components should take into account such heterogeneities at the scale of the component. This strong influence is experimentally demonstrated, and a way to take it into account in a mechanical simulation is proposed. (authors)

  6. Core Stability of Vertex Cover Games

    OpenAIRE

    Fang, Qizhi; Kong, Liang; Zhao, Jia

    2008-01-01

    In this paper, we focus on the core stability of vertex cover games, which arise from vertex cover problems on graphs. Based on duality theory of linear programming, we prove that a balanced vertex cover game has a stable core if and only if every edge belongs to a maximum matching in the underlying graph. We also prove that for a totally balanced vertex cover game, the core largeness, extendability, and exactness are all equivalent, which implies core stability. Furtherm...

  7. Core Processes: Earth's eccentric magnetic field

    DEFF Research Database (Denmark)

    Finlay, Chris

    2012-01-01

    Earth’s magnetic field is characterized by a puzzling hemispheric asymmetry. Calculations of core dynamo processes suggest that lopsided growth of the planet’s inner core may be part of the cause.......Earth’s magnetic field is characterized by a puzzling hemispheric asymmetry. Calculations of core dynamo processes suggest that lopsided growth of the planet’s inner core may be part of the cause....

  8. Characterizing core stability with fuzzy games

    OpenAIRE

    Shellshear, Evan

    2009-01-01

    This paper investigates core stability of cooperative, TU games via a fuzzy extension of the totally balanced cover of a TU game. The stability of the core of the fuzzy extension of a game, the concave extension, is shown to reflect the core stability of the original game and vice versa. Stability of the core is then shown to be equivalent to the existence of an equilibrium of a certain correspondence.

  9. Core trénink ve florbale

    OpenAIRE

    Mašková, Alžběta

    2014-01-01

    Title: Use of core training in floorball Objectives: Present an overview of research papers regarding core training and its possible use in floorball Tasks: First aim of this thesis is to provide description and explanation of the core training by using available literature, research papers, bachelor or magister thesis and also thesis of the coaching school. Second aim is to analyze the necessary components of floorball player's performance relative to the core training. This is followed by a...

  10. Influence of core electrons on plasmon oscillations

    Science.gov (United States)

    Lipparini, E.; Pederiva, Francesco

    1993-09-01

    Core electrons constitute a polarizable background which tends to screen the plasma oscillations. The influence of core electrons on plasmon dispersion is studied with sum rule techniques. Analytical expressions are derived for the surface plasmon of flat surfaces and of small metal particles. Core polarization explains semiquantitatively the blue-shift of the surface plasmon recently observed in silver systems.

  11. Mars: a new core-crystallization regime

    NARCIS (Netherlands)

    Stewart, A.J.; Schmidt, M.W.; van Westrenen, W.; Liebske, C.

    2007-01-01

    The evolution of the martian core is widely assumed to mirror the characteristics observed for Earth's core. Data from experiments performed on iron-sulfur and iron-nickel-sulfur systems at pressures corresponding to the center of Mars indicate that its core is presently completely liquid and that

  12. Common Core: Teaching Optimum Topic Exploration (TOTE)

    Science.gov (United States)

    Karge, Belinda Dunnick; Moore, Roxane Kushner

    2015-01-01

    The Common Core has become a household term and yet many educators do not understand what it means. This article explains the historical perspectives of the Common Core and gives guidance to teachers in application of Teaching Optimum Topic Exploration (TOTE) necessary for full implementation of the Common Core State Standards. An effective…

  13. Simplifying the ELA Common Core; Demystifying Curriculum

    Science.gov (United States)

    Schmoker, Mike; Jago, Carol

    2013-01-01

    The English Language Arts (ELA) Common Core State Standards ([CCSS], 2010) could have a transformational effect on American education. Though the process seems daunting, one can begin immediately integrating the essence of the ELA Common Core in every subject area. This article shows how one could implement the Common Core and create coherent,…

  14. Improving Core Strength to Prevent Injury

    Science.gov (United States)

    Oliver, Gretchen D.; Adams-Blair, Heather R.

    2010-01-01

    Regardless of the sport or skill, it is essential to have correct biomechanical positioning, or postural control, in order to maximize energy transfer. Correct postural control requires a strong, stable core. A strong and stable core allows one to transfer energy effectively as well as reduce undue stress. An unstable or weak core, on the other…

  15. Full MOX core design for PWR

    Energy Technology Data Exchange (ETDEWEB)

    Komano, Y.; Tochihara, H.; Ishida, M. [Mitsubishi Heavy Industries Ltd., Tokyo (Japan)

    1999-12-01

    Full MOX core design for APWR was analyzed in nuclear design, fuel integrity analysis, thermal hydraulic design and safety analysis et. al. Feasibility of Full MOX core was confirmed from these analyses without any large modifications. Full MOX PWR core has very good characteristics in which single Pu content in an assembly, burnable poison free, higher burnup and longer cycle operation are feasible. (author)

  16. Reinforcement core facilitates O-ring installation

    Science.gov (United States)

    1965-01-01

    Reinforcement core holds O-ring in place within a structure while adjacent parts are being assembled. The core in the O-ring adds circumferential rigidity to the O-ring material. This inner core does not appreciably affect the sectional elasticity or gland-sealing characteristics of the O-ring.

  17. Heterogeneity and anisotropy of Earth's inner core

    NARCIS (Netherlands)

    Deuss, Arwen|info:eu-repo/dai/nl/412396610

    2014-01-01

    Seismic observations provide strong evidence that Earth's inner core is anisotropic, with larger velocity in the polar than in the equatorial direction. The top 60-80 km of the inner core is isotropic; evidence for an innermost inner core is less compelling. The anisotropy is most likely due to

  18. Identifying Core vs. Non-Core Activities of Household Members

    Directory of Open Access Journals (Sweden)

    Mahdieh Allahviranloo

    2016-02-01

    Full Text Available Understanding scheduling behavior of households has been the focus of research for nearly half a century. Presumably activity engagement is being impacted by the importance of the activity to household members as well as time and cost constraints. Depending on the level of time budget, household members would eliminates some activities from the agenda or replace them with higher priority ones. In this paper, in order to capture the importance of different activities, we propose a methodology to schedule household activities under different levels of uncertainty about the importance of the activity. In this approach we combine discrete choice models and concepts of Fuzzy logic to identify core versus non-core activities in the agenda. The possibility of inclusion of an activity is the agenda is computed by estimating the expected importance of the activity and mapping to a set of fuzzy graphs. Activity scheduling and selection is then modeled as the outcome of a mixed integer optimization problem, in which the objective function is maximizing the expected desirability gained from activities and total saved time, subject to network connectivity, time windows, time budget and cost budget constraints.

  19. ARTEMISTM Core Simulator: Latest Developments

    Science.gov (United States)

    Hobson, Greg; Bolloni, Hans-Wilhelm; Breith, Karl-Albert; Dall'Osso, Aldo; van Geemert, René; Haase, Hartmut; Hartmann, Bettina; Leberig, Mario; Porsch, Dieter; Pothet, Baptiste; Riedmann, Michael; Sieber, Galina; Tomatis, Daniele

    2014-06-01

    AREVA has developed a new coupled neutronics/thermal-hydraulics code system, ARCADIA®. It makes use of modern computing resources to enable more realistic reactor analysis as improved understanding of nuclear reactor behavior is the basis for efficient margin management, i.e. optimization of safety and performance. One of the principal components of this new system is the core simulator, ARTEMIS™. The purpose of this paper is to recall its features, present the latest developments and give a summary of the validation tests.

  20. HPLWR fine mesh core analysis

    Energy Technology Data Exchange (ETDEWEB)

    Temesvari, E.; Maraczy, C.; Hegyi, G.; Hordosy, G.; Molnar, A. [Hungarian Academy of Sciences, Budapest (Hungary). Centre for Energy Research

    2014-08-15

    The European version of Supercritical Water Reactors (SCWR), the High Performance Light Water Reactor (HPLWR) operates in the thermodynamically supercritical region of water. Our basic objective was to elaborate a stationary coupled neutronic-thermohydraulic code capable for the calculation of the actual 3-pass core design with fuel assembly clusters. The calculations covered the neutronic transport calculations of HPLWR fuel assemblies, the coupled neutronic-thermohydraulic global calculations and the pin-wise analysis. Applying conservative assumptions, the relation to the linear heat rate and maximum cladding temperature limits was checked for the equilibrium cycle of HPLWR with this new code system.