Effect of Pressure on Carbon monoxide Oxidation on Titania Supported Platinum Nanoparticles Catalyst

Thermographic testing methodology was developed to facilitate measurements of particle dimension and substrate influence in heterogeneous catalysts. A screening chip with several areas of less stress silicon nitride membranes which displays less heat conductivity and heat capacity was used. Heat produced during the reaction on catalysts deposited on membranes was established through IR camera which gave the value of the turn over frequency. Effect of pressure on CO conversion on titania supported Pt particles of different dimension was measured on 120 catalysts concurrently. The reaction was studied at various O2 and CO pressures at 170 ℃ and 240 ℃. At these temperature conditions, activity increased with increase of O2 and CO pressure, in agreement with previous reports

Temperature Effects on the Corrosion Inhibition of Mild Steel in Sulfuric Acid Solution by Acacia senegal Gum with Halide Ions

The effects of temperature on the inhibitive effect of naturally occurring Acacia senegal gum exudate on the corrosion of mild steel in sulfuric acid was studied between 35 and 70 °C using electrochemical impedance spectroscopy and potentiodynamic polarization methods. Findings showed that Acacia senegal gum exudate decreases the corrosion rate of mild steel. The inhibition efficiency declined with raising temperature above 35 °C. The increase in the corrosion rate with increasing temperature was observed for both uninhibited and inhibited systems. Addition of halide ions to the Acacia senegal gum exudate solution enhanced the corrosion inhibition efficiency because of synergistic effects, achieving higher performance with iodide ions as compared to bromide ions. However, the synergistic effects declined above 35 °C up to 70 °C due to temperature effects. It has been observed that increasing temperature adversely affected inhibition efficiencies of both Acacia senegal gum exudate and the synergy between Acacia senegal gum exudate and halide ions. Corrosion rates of mild steel, inhibition efficiencies of Acacia senegal gum exudate and the synergistic effects of halide ions from polarization and impedance measurements were consistent. Keywords: temperature, corrosion, mild steel, synergistic effects, Acacia senegal, gum exudate

Carbon Monoxide Oxidation on Model Planar Titania Supported Platinum Nanoparticles Catalyst

A high-throughput (parallel) thermographic screening methodology was developed to enable the measurements of the particle size and support influence on heterogeneous catalysts. A high throughput screening chip has been used to establish the catalytic activity of titania supported platinum nanoparticles catalyst for CO oxidation reaction. The catalytic activity of Pt nanoparticles between 1.3 to 7.8 nm has been investigated for CO conversion at a pressure of 0.11 and 1.1 mbar with O2:CO ratio of 1:1 at 80 °C and 0.6, 1.1 and 2.4 mbar at O2:CO ratio of 1:1 at 240 °C. At these experimental conditions, there was an increase in the TOF with decreasing particle size for instance, at 80 °C and O2:CO ratio of 1:1, total pressure of 0.11 and 1.1 mbar, the TOF increased from 0.01 s–1 to 0.171 s–1 with decreasing Pt particle size from 7.8 to 1.3 nm, respectively. However, Pt nanoparticles catalyst displayed higher activity at higher temperature, for example, the TOF increased from 3.312 s–1 to 4.355 s–1 at O2:CO ratio of 1:1, total pressure of 0.6 and 1.1 mbar, respectively, for Pt particle size of 1.3 nm in agreement with the previous reports. Results show that CO oxidation on titania supported Pt nanoparticles catalyst is particle size dependent. On the other hand, findings from XPS measurements show no major change in the particle size after the reaction thus, reflecting the stability of Pt particles. While there is no apparent consensus in the literature reports on the activity trend with particle size for this system, these findings are consistent with most of the previously reported findings. Keywords: platinum; titania; nanoparticles; thermography; CO oxidation

A structural view of egg coat architecture and function in fertilization.

Species-restricted interaction between gametes at the beginning of fertilization is mediated by the extracellular coat of the egg, a matrix of cross-linked glycoprotein filaments called the zona pellucida (ZP) in mammals and the vitelline envelope in nonmammals. All egg coat subunits contain a conserved protein-protein interaction module-the "ZP domain"-that allows them to polymerize upon dissociation of a C-terminal propeptide containing an external hydrophobic patch (EHP). Recently, the first crystal structures of a ZP domain protein, sperm receptor ZP subunit zona pellucida glycoprotein 3 (ZP3), have been reported, giving a glimpse of the structural organization of the ZP at the atomic level and the molecular basis of gamete recognition in vertebrates. The ZP module is divided in two related immunoglobulin-like domains, ZP-N and ZP-C, that contain characteristic disulfide bond patterns and, in the case of ZP-C, also incorporate the EHP. This segment lies at the interface between the two domains, which are connected by a long loop carrying a conserved O-glycan important for binding to sperm in vitro. The structures explain several apparently contradictory observations by reconciling the variable disulfide bond patterns found in different homologues of ZP3 as well as the multiple ZP3 determinants alternatively involved in gamete interaction. These findings have implications for our understanding of ZP subunit biogenesis; egg coat assembly, architecture, and interaction with sperm; structural rearrangements leading to postfertilization hardening of the ZP and the block to sperm binding; and the evolutionary origin of egg coats

Tracking Down the ZP Domain: From the Mammalian Zona Pellucida to the Molluscan Vitelline Envelope

Oocytes from virtually all organisms are surrounded by at least one coat. This specialized extracellular matrix, called the zona pellucida (ZP) in mammals and the vitelline envelope (VE) in nonmammals, has a structural function and plays essential roles in oogenesis, fertilization, and early development. During the last 15 years, compelling evidence has accumulated that all ZP/VE subunits polymerize using a conserved sequence, the ZP domain, so that the basic structural features of egg coat matrices have been maintained through evolution. Moreover, ZP domains have been identified in many other polymeric extracellular proteins from eukaryotes. This review compares the ultrastructure and molecular composition of egg coats from mollusc to human, suggests a common mechanism for assembly of ZP/VE proteins, and discusses alternative models of how these could be arranged within filaments

Sequence similarity between stereocilin and otoancorin points to a unified mechanism for mechanotransduction in the mammalian inner ear

RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.Abstract Background Interaction between hair cells and acellular gels of the mammalian inner ear, the tectorial and otoconial membranes, is crucial for mechanoreception. Recently, otoancorin was suggested to be a mediator of gel attachment to nonsensory cells, but the molecular components of the interface between gels and sensory cells remain to be identified. Hypothesis We report that the inner ear protein stereocilin is related in sequence to otoancorin and, based on its localisation and predicted GPI-anchoring, may mediate attachment of the tectorial and otoconial membranes to sensory hair bundles. Testing It is expected that antibodies directed against stereocilin would specifically label sites of contact between sensory hair cells and tectorial/otoconial membranes of the inner ear. Implications Our findings support a unified molecular mechanism for mechanotransduction, with stereocilin and otoancorin defining a new protein family responsible for the attachment of acellular gels to both sensory and nonsensory cells of the inner ear.Published versio

Einsatz digitaler Bildanalyse zur Unterscheidung Vaskulärer Anomalien im Kopf-Hals-Bereich

Die histologische Abgrenzung verschiedener Typen vaskulärer Anomalien, wie Lymphangiome, Hämangiome, Paragangliome, venöse und arteriovenöse Malformationen, Granuloma pyogenicum, gestaltet sich aufgrund der Heterogenität dieser Fehlbildungen als sehr schwierig. In dieser Arbeit wurde untersucht, inwiefern eine immunhistologische Quantifizierung von Präparaten vaskulärer Anomalien mittels digitaler Bildanalyse eine genauere Zuordnung der Gefäßmalformationen in ihre Subtypen ermöglicht. Hierzu wurden Gewebe vaskulärer Anomalien von 40 Patienten immunhistologisch untersucht, wobei fünf ausgewählte gefäßendothelassoziierte Marker (CD31, CD34, CLDN5, PDPN, VIM) eingesetzt wurden. Die Färbungen wurden mikroskopisch dokumentiert und eine digitale Bildanalyse und Quantifizierung der Kandidatenmarkerproteine innerhalb der untersuchten Gewebe durchgeführt. Ziel war hierbei, die Beurteilung der digitalen Bildanalyse als Methode zur Unterscheidung von Gefäßmalformationen. Durch die Betrachtung der Verhältnisse (Quotienten) der digital erfassten und quantifizierten immunhistochemischen Signalwerte, konnten Unterschiede im Expressionsmuster der Kandidatenproteine erkannt werden. In der Gruppe der pyogenen Granulome zeigten sich Quotienten aus CLDN5/CD34 (p<0,01) und VIM/CD34 (p<0,05) als einsetzbar, um eine Abgrenzung zu anderen vaskulären Anomalien zu erreichen (Abbildung 47A-C). Über die Quotienten PDPN/CLDN5 (p<0,001) und PDPN/CD34 (p<0,01) war hingegen eine Unterscheidung von Lymphangiomen zu allen anderen untersuchten vaskulären Anomalien möglich (Abbildung 47A-D). Der Einsatz der weit etablierten Endothelmarker CD34 und CD31 zeigte erwartungsgemäß eine deutliche Immunreaktivität der Gefäßendothelien. Der Nutzen von PDPN zur Abgrenzung von vaskulären Anomalien lymphatischen Ursprungs von anderen Malformationen konnte aufgezeigt werden. Dies unterstreicht die Zuverlässigkeit von PDPN als lymphangischen Marker, der im Rahmen der histopathologischen Untersuchung vaskulärer Anomalien eine Differentialdiagnose erlaubt. Der Nachweis von CLDN5 im Endothel vaskulärer Anomalien unterstützt dessen zuvor postulierte Rolle bei der vaskulären Differenzierung und Aufrechterhaltung der Gefäßstruktur. Hervorzuheben sind die Ergebnisse des möglichen diagnostischen Nutzens einer digitalen Quantifizierung der Markerproteinexpressionsmuster. Im Hinblick auf zukünftige diagnostische Methoden ist zu erwarten, dass der Einsatz digitaler Hilfsmittel in der klinisch pathologischen Diagnostik weiter zunehmen wird. Ziel sollte es daher sein, digitale Verfahren zur histologischen Auswertung von Gewebeproben zu etablieren. Die digitale Bildanalyse erweist sich als vielversprechendes Werkzeug zur Erfassung der Expressionsunterschiede der eingesetzten Gefäßmarker im Gewebe vaskulärer Anomalien. Da sich nach digitaler Quantifizierung deutliche Unterschiede im Expressionsgrad der untersuchten Kandidatenproteine innerhalb der vaskulären Anomalien zeigten, eignet sich diese Methode, die sehr heterogene Gruppe der Gefäßfehlbildungen genauer zu klassifizieren. Zu betonen ist allerdings, dass deren Anwendung nicht die Diagnose eines erfahrenen Pathologen ersetzen, sondern vielmehr als diagnostisches Hilfsmittel dienen soll. Wichtig ist hierbei, dass die immunhistochemischen Ergebnisse im Zusammenhang mit dem klinischen Bild betrachtet werden. Noch finden sich häufig Widersprüche zwischen der histopathologischen und der klinischen Zuordnung der Anomalien zu einer der jeweiligen Untergruppen. Dies kann zu Fehldiagnosen beitragen, die sich negativ auf die Wahl der Therapie und deren rechtzeitige Anwendung auswirken. In diesem Zusammenhang kann die digitale Quantifizierung eine Hilfestellung bieten, um die Diagnostik zu objektivieren und zu optimieren. Dass dies möglich ist, konnte in der vorliegenden Arbeit gezeigt werden. Es wurde zudem deutlich, dass sich die Diagnostik der Gefäßfehlbildungen nicht auf einzelne immunhistochemische Marker beschränken kann. Ziel ist es, ein „Expressionsprofil“ für jedes Gewebe zu erstellen, das auf charakteristischen Proteinenexpressionsmustern der Marker beruht. Die vorliegende Arbeit zeigt, dass bereits unter Einsatz von fünf Markerproteinen eine Abgrenzung innerhalb dieser vaskulären Anomalien möglich ist. Weiterführende Studien mit einer höheren Anzahl vaskulärer Anomalien und zusätzlicher Markerproteine sollten sich anschließen, da hierdurch eine Unterscheidung aller Gefäßfehlbildungen zu erwarten ist. Dies wird das Ziel zukünftiger Untersuchungen sein

Crystal structure of the ZP-N domain of ZP3 reveals the core fold of animal egg coats

Species-specific recognition between the egg extracellular matrix (zona pellucida) and sperm is the first, crucial step of mammalian fertilization. Zona pellucida filament components ZP3 and ZP2 act as sperm receptors, and mice lacking either of the corresponding genes produce oocytes without a zona pellucida and are completely infertile. Like their counterparts in the vitelline envelope of non-mammalian eggs and many other secreted eukaryotic proteins, zona pellucida subunits polymerize using a 'zona pellucida (ZP) domain' module, whose conserved amino-terminal part (ZP-N) was suggested to constitute a domain of its own. No atomic structure has been reported for ZP domain proteins, and there is no structural information on any conserved vertebrate protein that is essential for fertilization and directly involved in egg-sperm binding. Here we describe the 2.3 ångström (A) resolution structure of the ZP-N fragment of mouse primary sperm receptor ZP3. The ZP-N fold defines a new immunoglobulin superfamily subtype with a beta-sheet extension characterized by an E' strand and an invariant tyrosine residue implicated in polymerization. The structure strongly supports the presence of ZP-N repeats within the N-terminal region of ZP2 and other vertebrate zona pellucida/vitelline envelope proteins, with implications for overall egg coat architecture, the post-fertilization block to polyspermy and speciation. Moreover, it provides an important framework for understanding human diseases caused by mutations in ZP domain proteins and developing new methods of non-hormonal contraception

The PLAC1-homology region of the ZP domain is sufficient for protein polymerisation

BACKGROUND: Hundreds of extracellular proteins polymerise into filaments and matrices by using zona pellucida (ZP) domains. ZP domain proteins perform highly diverse functions, ranging from structural to receptorial, and mutations in their genes are responsible for a number of severe human diseases. Recently, PLAC1, Oosp1-3, Papillote and CG16798 proteins were identified that share sequence homology with the N-terminal half of the ZP domain (ZP-N), but not with its C-terminal half (ZP-C). The functional significance of this partial conservation is unknown. RESULTS: By exploiting a highly engineered bacterial strain, we expressed in soluble form the PLAC1-homology region of mammalian sperm receptor ZP3 as a fusion to maltose binding protein. Mass spectrometry showed that the 4 conserved Cys residues within the ZP-N moiety of the fusion protein adopt the same disulfide bond connectivity as in full-length native ZP3, indicating that it is correctly folded, and electron microscopy and biochemical analyses revealed that it assembles into filaments. CONCLUSION: These findings provide a function for PLAC1-like proteins and, by showing that ZP-N is a biologically active folding unit, prompt a re-evaluation of the architecture of the ZP domain and its polymers. Furthermore, they suggest that ZP-C might play a regulatory role in the assembly of ZP domain protein complexes

Telaah Literatur Potensi Lutein dari Bunga Marigold Lokal sebagai Suplemen Kesehatan

Abstract Lutein is a type of xanthophyll that accumulated predominantly in eye macula, and is distributed in several parts of the human body, such as skin and brain. Lutein accumulation in the human body is associated with the health benefits of lutein, including being an antioxidant and protecting, the eyes and skin from exposure to blue light, and playing an important role to maintain human cognitive health. Lutein cannot be synthesized by human, so consumption of lutein can be obtained from foods such as fruits and green vegetables, as well as from supplements. The purpose of writing this article was to increase awareness of the importance of adequate lutein intake early in the body, as well as increased research interest in exploring local resources as a potential source of lutein, the Mega Orange marigold from Bali as a raw material for health supplements. The potential lutein article as health supplement was prepared by reviewing articles from international journals and followed by testing the composition of carotenoids in Mega Orange marigolds and a health supplement product by HPLC analysis. Various studies and article publications regarding the health benefits of lutein have been found in the last decade. There are at least two main benefits of lutein, namely as an antioxidant and to maintain the health of organs such as the eyes, brain and skin. Meanwhile, the local marigold flower variety of Mega Orange contains carotenoids lutein and zeaxanthin up to 13.88 mg/g dry weight, and this result is in the range of lutein concentrations in marigold flowers that grow in Thailand. Mega Orange marigold is a potential source of lutein that can be used as raw materials for health supplement products. The importance of lutein intake for the human body makes the use of lutein from local marigolds in the manufacture of health supplements needs to be optimized and utilized. Abstrak Lutein termasuk jenis xantofil yang terakumulasi secara dominan pada makula, serta terdistribusi pada beberapa bagian tubuh manusia seperti kulit dan otak. Akumulasi lutein pada tubuh manusia dikaitkan dengan manfaat kesehatan lutein, diantaranya sebagai antioksidan serta melindungi mata dan kulit dari paparan sinar biru, dan memainkan peranan penting untuk menjaga kesehatan kognitif manusia. Lutein tidak dapat disintesis oleh manusia, sehingga konsumsi lutein dapat diperoleh dari makanan seperti buah dan sayuran hijau, serta dari suplemen. Tujuan penulisan artikel ini adalah untuk meningkatkan kesadaran akan pentingnya kecukupan asupan lutein sejak dini dalam tubuh, serta menambah minat penelitian akan eksplorasi sumber daya lokal yang sebagai sumber potensial lutein yaitu bunga marigold Mega Orange dari Pulau Bali sebagai bahan baku suplemen kesehatan. Artikel potensi lutein sebagai suplemen kesehatan ini disusun dengan menelaah artikel-artikel pada jurnal internasional dan diikuti dengan pengujian komposisi karotenoid pada bunga marigold Mega Orange dan satu produk suplemen kesehatan dengan analisis Kromatografi Cair Kinerja Tinggi (KCKT). Berbagai penelitian dan publikasi artikel mengenai manfaat kesehatan lutein telah banyak ditemukan dalam dekade terakhir. Setidaknya terdapat dua manfaat utama lutein, yaitu sebagai antioksidan dan untuk menjaga kesehatan organ tubuh seperti mata, kulit, dan otak. Adapun, bunga marigold lokal varietas Mega Orange mengandung karotenoid lutein dan zeaksantin hingga 13,88 mg/g berat kering, dan hasil ini berada pada rentang konsentrasi lutein dalam bunga marigold yang tumbuh di Thailand. Bunga marigold Mega Orange merupakan sumber potensial lutein yang dapat digunakan sebagai bahan baku produk suplemen kesehatan. Pentingnya asupan lutein bagi tubuh manusia menjadikan pemanfaatan lutein dari bunga marigold lokal dalam pembuatan suplemen kesehatan perlu dioptimalkan dan dimanfaatkan