bluuebunny/crossref_metadata_2025 huggingface dataset:
Mensa Project: Rig Operations
Authors: Saucier B.J. , Southworth M.E. , Browning S.W. , Wainwright W.M. , Piley D.A.
Published: October 2008

Mensa's subsea completion operations were conducted from a moored semi-submersible in 5300 ft. water. The rig based completion operations represent a milestone in deepwater subsea completion operations technology. The paper will focus on unique subsea completion operations employed from the rig, completion mooring operations, and the completion interface issues encountered during the installation of the subsea system.

Introduction

The Transocean George Richardson drilling rig was selected for executing the completion operations at Mensa. This selection was based on pre-existing work which had been performed jointly with Shell Offshore Inc. (SOl) on other projects, rig capacities, and schedule availability. The rig is a DNV classed, GVA 4500 semisubmersible. The deepwater operating environment at Mensa presented challenges in executing the offshore operations. Early rig selection and identification of key rig limitations contributed to the offshore operational success. Installation operations were governed by project economics, which drove the installation approach and sequence of operations. Subsea completion equipment interfaces with the rig were planned and identified early in the project engineering phase. To achieve the project goals, operations engineering and planning focused in the following areas:mooringlstationkeepingsubsea hardware interfaces with rig infrastructureBOP interfacesvariable deck load and lift capacitiesriser tensioningunloading operationsnovel installation techniques

Rig Operations

Early rig selection and identification of rig interfaces specific to the Mensa subsea completion allowed a unitized hardware and operational plan to be developed. Development of a "rigbased" sequence of operations and installation plan provided a basis from which the planning and engineering activities were structured. This enabled identification of areas that would impact the rig-based installation operations. Preliminary installation procedures were then developed early in the project development cycle. The following discussion highlights the rig interface challenges which were identified and resolved during the subsea installation completion cycle.

Completion Mooring Operations

SOl recognized that available anchor handling support vessels in the Gulf of Mexico were not capable of running and recovering anchors at Mensa. In January, 1995, SOI contracted to construct a purpose built anchor handling vessel for mooring the Richardson at Mensa to support initial development drilling operations. The vessel, Ross Chouest, was delivered in July of 1996 with 13,500 total BHP and 187 tons of bollard pull. Dual 500 mt winches capable of holding 6,500 ft. of 3¾' workwire were installed on the vessel to handle all eight 18mt anchors with chain and wire. The dedicated anchor handling vessel further supported the completion operations in the following areas:flowline/umbilical jumper installationtree mobilization/offloading (Fig. 1)fluid displacement operations
The Incredible Story of the Worlds Oceans: Will Global Warming Have an Impact?
Authors: Westbrook Gerald T.
Published: October 2008

The Magnitude of Nature's Forces

The more one understands the working of our planet in general and it's climate in particular, the more one becomes overcome with awe at the magnitude, complexity and grandeur of the natural scheme of things. Indeed, one can easily adopt a strong religious outlook to this work. So it is appropriate to open this paper with an example that has a strong religious couple. The emergence of the Earth from the Last Ice Age saw repeated warmings and coolings from about 20,000 years ago (20 KYs) to about 8 KYs before present (8 KYBP), when the Earth, approached its's present temperature. Over the past 20 KYs the oceans underwent about a 120 meter rise (a 400 foot rise) from their lowest levels seen in the Last Ice Age. Over the interval from 17 to 7.5 KYBP, as the ice sheets melted, and the oceans rose, the level of the Mediterranean gradually increased from 110 meters below present (mbp) to 15 mbp. At the end of this period an incredible event1 occurred in and around the Black Sea, coupled to this sea level rise. The Black Sea started as a lake. And its level oscillated over this 9.5 KY period, from 140 mbp to 15 to 127 to 156 mbp (Figure I). There was thus a head of 141 meters between the Mediterranean Sea and the Black Lake and sea water started to come through around the year 5500 Be. This occurred, first as a trickle, but soon as a torrent, with 1000 times the flow of Niagara Falls. This sea water intrusion would soon turn into an absolute disaster. It is estimated that the sea level rose 15 – 30 cms per day. The inhabitants would have had to retreat as much as one kilometer per day2 over a period of 100 – 200 days. Shelters would have disappeared rapidly as would most possessions and food, which would soon become the most pressing problem. Indeed this was an incredible event. Could this have been Noah's flood? We may never know. However legends of a great flood abound in many cultures around the world. If it was not Noah's flood it surely was one of Biblical proportions and helps depict the titanic magnitude of natural events around or connected to the behavior of our oceans.

Background

Global warming, as an environmental issue and as a priority of the Clinton/Gore Administration, has been much in the news with all of the publicity and hype around the Kyoto Treaty. The global warming issue is based on a gradually increasing level of greenhouse gases (GHGs) in our atmosphere, primarily CO2, that will increase the energy retained within the Earth's greenhouse system. There is no argument that such a system exists. And GHGs are real as is the global warming phenomenon. (Indeed, without the natural GHGs the Earth's average temperature would drop as much as 33° C. It should be noted in passing that the dominant GHG in this natural global warming is H2O, not CO2, not CH4, not chloro-flourocarbons, but H2O).
Optimizing 3D Seismic Surveys: Off-the-Shelf? or Out-of-the-Box?
Authors: Thomsen Leon
Published: October 2008

In seeking to optimize 3D seismic surveys, it is natural to define this as a minimization of the cost/benefit ratio resulting from such a survey. One way to do this is to minimize the costs of the survey (without major damage to the benefits), This frequently entailsuse of off-the-shelf components at every stage, thus avoiding the costs of customized equipment and procedures. A second way to minimize the same ratio is to maximize the benefits (without letting the costs get out of hand). Of course, a marginal increase in benefits may result from modifications of conventional design parameters or processing steps. However, the greatest increase in benefits is likely to occur if a radically different concept is employed. Such a new style of survey ("out-of-the-box") may have a lower cost/benefit ratio, even if the associated costs are higher! As an example, consider a 3D multicomponent survey. The costs of such a survey are certainly greater, but the increased benefits can often be worth the extra costs. These can include better P-wave imaging, better C-wave imaging, better subsurface formation characterization, and better timelapse repeatability.

What is it we optimize?

In this era of sharpened pencils, it is too common to assume that what we want to optimize is the costs of the survey. This is, of course, a laudable goal, and one easy to quantify. By contrast, the benefits of the survey may be less easy to quantify in precise economic terms. Nonetheless, I take it a self-evident that the parameter which we really want to optimize is the cost/benefit ratio, rather than the cost itself. The calculating of benefits is a complex task, beyond the scope of this work, and necessarily specific to each particular project. Nonetheless, it is appropriate to give the subject its proper emphasis by phrasing the optimization problem in this explicit way. If our goal is to minimize the cost/benefit ratio, this can obviously be done either by minimizing costs, by maximizing benefits, or some optimal combination of both strategies. A lot of attention has been paid, in the exploration community, to the strategy of minimizing costs, through clever design of the acquisition, and efficient pre-planned processing, and integrated interpretation, thus decreasing cycle time and saving costs in ways which are now obvious. It would be redundant to repeat or even to review those advances here. Instead, we concentrate the emphasis here on the other end of the continuum: to increase the value of the survey. Even if thecosts rise as a result of such a strategy, if the benefits rise even more, it is economically advantageous to do it. After all, this is the fundamental strategy of 3D itself: 3D is doubtless more costly than 2D, and in fact this dissuaded many companies from pursuing it in the eighties. But, after it was clearly demonstrated. by the early nineties, that 3D surveys yield benefits which more than compensate for the added cost, the utilization of such surveys skyrocketed, so that now, only 5 years later, it is routine.
Gravity Studies Across the Sula Arc
Authors: Rabinowitz Philip D. , Syed Fakhar H. , McCabeKexas Robert
Published: October 2008

The basins of the Sulu and Celebes Seas are located within a complex geodynamic zone between Pacific, Indian-Australian, Eurasian and Philippine Sea Plates. Three models have been proposed for the tectonic origin of these basins; trapped fragments from a larger oceanic plate, back-arc spreading, and rifting from the Southeast Asia margin. The basins areseparated by the shallow partly emerged Sulu volcanic Ridge extending from Western Mindano to Northeast Borneo. The Sulu Volcanic Ridge is bounded on the northwest by the Sulu Trench with evidence for subduction of the Sulu Sea beneath the Sulu Ridge. The nature of the southeast margin of the Sulu Ridge is difficult to assess because of a thick sedimentary cover and the lack of reflection or refraction seismic data. Hamilton (1979) and Rangin (1989) proposed flipping of subduction along the Sulu Arc from its southeast margin (subduction of the Celebes Sea under the Sulu Arc) to its northwest margin (subduction of the Sulu Sea under the Sulu Arc). Gravity observations are modeled across the Sulu Arc and adjacent basinal structures using existing seismic data. The gravity modeling is consistent with the concept that subduction zones exist along both flanks of the Sulu Arc and also that extinct spreading centers exist in both the Sulu and Celebes Seas.

Introduction

The Southeastern Asian region where four prominent plate boundeies converge is an area of unique complexity marked by active arc-arc or arc-continent collision zones, and subduction zones. The Sulu and Celebes Seas are located within this region between the Pacific, Indian Australian, Eurasian, and Philippine Sea Plates (Fig. 1).

The Sulu Basin is a small marginal basin, elongated northeast southwest, bounded by Palawan, Negros, Negros Trench, Zamboanga, Sulu Ridge, and Borneo (Fig. 1). The Sulu Sea is about 400 km wide and is divided by a bathymetric high, the Cagayan Ridge. The Cagayan Ridge is an elongated submarine volcanic ridge parallel to the Palawan Trench which divides the Sulu Sea into two sub-basins, the Northwest Sulu Basin and the Southeast Sulu Basin. The Cagayan Ridge has been interpreted as an island arc associated with the Palawan Trench (Holloway, 1982) and also a remnant volcanic arc for the Sulu Arc. Palawan Island, located on theNorthwest Sulu Basin margin is a part of an older Eocene subduction complex associated with the extinct subduction atthe Palawan Trench (Fig. 1) (Holloway, 1982). The Northwest Sulu Basin is filled by relatively undeformed sediment disconformably overlying the deformed strata. The Southeast Sulu Basin is filled by 1–2 km thick sediments overlaying the acoustic basement ranging 4500 to SWOrn in depth (Rangin and Silver, 1990).

The Celebes Sea is underlain by oceanic crust and is bordered by the Cotabato Trench in the northeast and North Sulawesi Trench in the south. The sedimentary thickness in most of the Celebes Basin is about 1 km and increase to 2 km along its Southern margin (Hamilton, 1979).
Low Cost 10 MMCFID Gas to Syncrude Plant for Associated Gas
Authors: Antia David D.J. , Seddon Duncan
Published: October 2008

A low cost 10 MMCFID gas to sycrude plant design is described. The plant is suitable for retrofitting on to platforms, drilling rigs and ships/barges. Three different plant designs are described costing between US $10 and 20 MM with a product yield of >800 Bbls/d. Operating costs are estimated at $1.8 MM/a. The plant weighs c.3300 tonnes and occupies <800 sqm. The syncrude product is blended with the field's crude oil.

Introduction

The gas to syncrude technology was first commercialized in the 1930's. Since the 1930's, commercial plants have been built in the USA, South Africa, Japan, Germany, China and Malaysia. Currently, commercial plants are in operation in Malaysia and South Africa. Large onshore plants are currently planned for Russia, Bangladesh, and Qatar. These plants, if built, will produce a total of>1 MM Bbls of syncrude a day from natural gas.

The feasibility of placing small-scale gas to syncrude plants offshore, either on a standalone basis, or to process associated gas has been examined elsewhere 1- 9 The conversion process consists of three key stages: -Production of a synthesis gas (a mixture of carbon monoxide and hydrogen) from natural gas by either partial oxidation or steam reformingConversion of the synthesis gas to hydrocarbons using Fischer-Tropsch technologySeparation of liquid hydrocarbons (syncrude) from the product gas and water.

The key problems in introducing this technology in the offshore environment are:-Cost (the cost of a traditional plant is high by comparison with typical offshore process equipment)The requirement to use an oxygen source for the manufacture of the synthesis gas. Some oil companies are not prepared to consider the use of an oxygen plant offshore (VSA or cryogenic), while a steam reformer is too large for most offshore locations.Plant size. A conventional plant cannot be retrofitted onto an existing production platform and requires a comparatively large plant area (3600 sq m with an operating weight of c.19 K tonnes, for a 100 MMCFIDplant)2

The challenge faced by a supplier of gas to syncrude plants is to create a plant, which has the following characteristics: -A low capital cost relative to the volume of gas processed. This capital cost should ideally be less than $1.5 MMIMMCFID of gas processed.Is able to process gas volumes in the range 5 to 12 MMCFID. This will allow the plant to remove a flaring or reinjection requirement for most offshore fields. Plant operation should be unaffected by motion.Significantly reduces the field's emissions of greenhouse gasesProvides additional energy for the field, which can be used to provide motive power, etc.Uses commercially proven generic catalysts and technology. It should not need a steam reformer, auto thermal reformer or an oxygen plant.Is designed to contain low technology equipment, which will allow fabrication in third world countries.
The Importance of Titrating Antibodies for Immunocytochemical Methods
Authors: Hoffman Gloria E. , Le Wei Wei , Sita Luciane V.
Published: October 2008

When using immunocytochemistry, investigators may not know how to optimize staining or how to troubleshoot the method when staining fails. Lacking are guides for comparing techniques and applying information derived from one staining method to another. Newer methods amplify signal detection, but will not necessarily work at the same primary antibody concentrations used for less sensitive reactions. Recommendations of optimal titers are often not accurate and are not usually accompanied by information on the method used to test those antibodies or the specifics of the assay. When the staining does not work, the investigators do not know how to determine if the antiserum is bad, the tissue is bad, or the method is inappropriate for their staining. This unit describes detailed procedures for determining optimal staining and applying that information to three common immunofluorescence methods. Lastly, a formula is provided for converting among the different methods. Curr. Protoc. Neurosci. 45:2.12.1‐2.12.26. © 2008 by John Wiley & Sons, Inc.
DNA‐Dependent DNA Polymerases
Authors: Kucera Rebecca B. , Nichols Nicole M.
Published: October 2008

This unit presents characteristics and reaction conditions of the DNA‐dependent DNA polymerases, including E. coli DNA polymerase I and its Klenow fragment, T4 DNA polymerase, native and modified T7 DNA polymerase, phi29 DNA polymerase, Bst DNA polymerase, and Taq DNA polymerase. The unit also provides overviews of other classes of thermophilic DNA polymerases used in PCR applications (described fully in UNIT 15.1), and the rapidly expanding class of lesion‐bypass DNA polymerases that play a role in DNA damage repair. Curr. Protoc. Mol. Biol. 84:3.5.1‐3.5.19. © 2008 by John Wiley & Sons, Inc.
RNA Polymerases
Authors: Paschal Beth M. , McReynolds Larry A. , Noren Christopher J. , Nichols Nicole M.
Published: October 2008

This unit describes DNA‐dependent, RNA‐dependent, and template‐independent RNA polymerases. DNA‐dependent RNA polymerases include the related bacteriophage T7, T3, and SP6 polymerases, the most commonly used RNA polymerases for in vitro transcription reactions. Reaction conditions to produce preparative quantities of transcribed RNA and labeled RNA probes are covered, as are the major applications of these reactions. Limitations of the E. coli RNA polymerase for these applications are also presented. The properties of the phi6 RNA‐dependent RNA polymerase (RdRp) and its use in RNAi experiments are also introduced. Poly(A) polymerase, a template‐independent polymerase, catalyzes the incorporation of AMP residues onto the free 3′‐hydroxyl terminus of RNA, utilizing ATP as a precursor. Specific reaction conditions of poly(A) polymerase, as well as applications including RNA tailing and 3′ end labeling, are discussed. Curr. Protoc. Mol. Biol. 84:3.8.1‐3.8.8. © 2008 by John Wiley & Sons, Inc.
DNA Repair Enzymes
Authors: Evans Thomas C. , Nichols Nicole M.
Published: October 2008

In vivo DNA damage impacts the genetic stability of an organism; therefore, multiple pathways utilizing a large number of enzymes have evolved to repair DNA damage. This unit focuses on enzymes involved in base excision repair (BER). The BER enzymes possessing N‐glycosylase activity can find and remove a wide variety of damaged bases in a sea of normal bases. The combination of unique substrate specificity, accuracy, and robust in vitro activity of many of these enzymes has led to their use in various experimental techniques, including site‐specific DNA cleavage. The enzymes described in this unit are active on many substrates including oxidized purines and pyrimidines, alkylated bases, abasic sites, pyrimidine dimers, deaminated cytosines, and deaminated adenines. Curr. Protoc. Mol. Biol. 84:3.9.1‐3.9.12. © 2008 by John Wiley & Sons, Inc.
PolyPhred Analysis Software for Mutation Detection from Fluorescence‐Based Sequence Data
Authors: Montgomery Kate T. , Iartchouck Oleg , Li Li , Loomis Stephanie , Obourn Vanessa , Kucherlapati Raju
Published: October 2008

The ability to search for genetic variants that may be related to human disease is one of the most exciting consequences of the availability of the sequence of the human genome. Large cohorts of individuals exhibiting certain phenotypes can be studied and candidate genes resequenced. However, the challenge of analyzing sequence data from many individuals with accuracy, speed, and economy is great. This unit describes one set of software tools: Phred, Phrap, PolyPhred, and Consed. Coverage includes the advantages and disadvantages of these analysis tools, details for obtaining and using the software, and the results one may expect. The software is being continually updated to permit further automation of mutation analysis. Currently, however, at least some manual review is required if one wishes to identify 100% of the variants in a sample set. Curr. Protoc. Hum. Genet. 59:7.16.1‐7.16.21. © 2008 by John Wiley & Sons, Inc.
Assessment of Histone Acetylation Levels in Relation to Cell Cycle Phase
Authors: Ronzoni Simona , Faretta Mario , Ballarini Marco , Pelicci PierGiuseppe , Minucci Saverio
Published: October 2008

Histone acetylation affects chromatin structural organization, thus regulating gene expression and DNA‐related cellular events. Levels of histone acetylation are tightly modulated in normal cells and frequently altered in tumors. Consequently, histone deacetylase inhibitors are currently being tested in clinical trials as anticancer drugs. Presented here is a protocol for measuring the degree of cellular histone tail acetylation, alone or in combination with DNA content to simultaneously evaluate cell ploidy and/or cell cycle progression. The procedure can also be employed to stain peripheral blood samples in order to assess mean histone acetylation levels in patients treated with histone deacetylase inhibitors. Curr. Protocol. Cytom. 46:7.35.1‐7.35.8. © 2008 by John Wiley & Sons, Inc.
Whole Blood Processing for Measurement of Signaling Proteins by Flow Cytometry
Authors: Chow Sue , Hedley David , Shankey T. Vincent
Published: October 2008

Signal transduction pathways link external stimuli with cellular responses, which normally regulate cell proliferation, death, and differentiation. The study of signal transduction was revolutionized through the development of phospho‐specific antibodies that recognize proteins only when they are phosphorylated at specific sites. As discussed by Nolan and co‐workers (UNIT here), one of the unique features of flow cytometry is its ability to perform correlated measurements of multiple phosphorylation states at the single cell level. This provides insight into the complexity of signaling networks that is not obtained by standard biochemical techniques. Furthermore, in combination with other phenotypic markers, flow cytometry can measure alterations in signaling pathways in subpopulations of cells. This clearly has wide potential for studying disorders of the hematopoietic and immune systems. Curr. Protocol. Cytom. 46:9.27.1‐9.27.19. © 2008 by John Wiley & Sons, Inc.
Moscow School of Probability Theory
Authors: Vere‐Jones David
Published: October 2008

A brief account is given of the growth and major contributions of the Moscow School of Probability, from its inception in the 1920s until approximately the end of the Second World War.
Isolation and Manipulation of Mouse Trophoblast Stem Cells
Authors: Himeno Emi , Tanaka Satoshi , Kunath Tilo
Published: October 2008

The isolation of stable trophoblast stem (TS) cell lines from early mouse embryos has provided a useful cell culture model to study trophoblast development. TS cells are derived from pre‐implantation blastocysts or from the extraembryonic ectoderm of early post‐implantation embryos. The derivation and maintenance of mouse TS cells is dependent upon continuous fibroblast growth factor (FGF) signaling. Gene expression analysis, differentiation in culture, and chimera formation show that TS cells accurately model the mouse trophoblast lineage. This unit describes how to derive, maintain, and manipulate TS cells, including DNA transfection and chimera formation. Curr. Protoc. Stem Cell Biol. 7:1E.4.1‐1E.4.27. © 2008 by John Wiley & Sons, Inc.
Contraction of free liquid ligaments
Authors: Li Ri , Ashgriz Nasser , Chandra Sanjeev , Andrews John R.
Published: October 2008

This article presents an experimental and theoretical study on the contraction of free, stable, and inviscid liquid ligaments under the action of surface tension forces. The ligament is considered as two blobs of arbitrary initial sizes connected by a central column with a constant and uniform radius. Based on the conservation of mass, momentum, and energy, a theoretical model is developed to predict the ligament length as a function of time, thereby predicting the lifetime of the ligament. The theoretical results are compared with our experimental measurements of the transient length of liquid ligaments ejected from an inkjet printhead, showing good agreement. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Acanthoscurrin fragment 101–132: Total synthesis at 60°C of a novel difficult sequence
Authors: Remuzgo César , Andrade Gustavo F. S. , Temperini Márcia L. A. , Miranda M. Terêsa M.
Published: October 2008

Glycine‐rich proteins (GRPs) serve a variety of biological functions. Acanthoscurrin is an antimicrobial GRP isolated from hemocytes of the Brazilian spider Acanthoscurria gomesiana. Aiming to contribute to the knowledge of the secondary structure and stepwise solid‐phase synthesis of GRPs' glycine‐rich domains, we attempted to prepare G101GGLGGGRGGGYG113GGGGYGGGYG123 GGY126GGGKYK132‐NH2, acanthoscurrin C‐terminal amidated fragment. Although a theoretical prediction did not indicate high aggregation potential for this peptide, repetitive incomplete aminoacylations were observed after incorporating Tyr126 to the growing peptide‐MBHA resin (Boc chemistry) at 60°C. The problem was not solved by varying the coupling reagents or solvents, adding chaotropic salts to the reaction media or changing the resin/chemistry (Rink amide resin/Fmoc chemistry). Some improvement was made when CLEAR amide resin (Fmoc chemistry) was used, as it allowed for obtaining fragment G113–K132. NIR‐FT‐Raman spectra collected for samples of the growing peptide‐MBHA, ‐Rink amide resin and ‐CLEAR amide resin revealed the presence of β‐sheet structures. Only the combination of CLEAR‐amide resin, 60°C, Fmoc‐(Fmoc‐Hmb)Gly‐OH and LiCl (the last two used alternately) was able to inhibit the phenomenon, as proven by NIR‐FT‐Raman analysis of the growing peptide‐resin, allowing the total synthesis of desired fragment Gly101–K132. In summary, this work describes a new difficult sequence, contributes to understanding stepwise solid‐phase synthesis of this type of peptide and shows that, at least while protected and linked to a resin, this GRP's glycine‐rich motif presents an early tendency to assume β‐sheet structures. © 2008 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 92: 65–75, 2009.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Oxidation of Diiron and Triiron Sulfurdithiolato Complexes: Mimics for the Active Site of [FeFe]‐Hydrogenase
Authors: Windhager Jochen , Seidel Raphael A. , Apfel Ulf‐Peter , Görls Helmar , Linti Gerald , Weigand Wolfgang
Published: October 2008

The oxidation of the hexacarbonyl(1,3‐dithiolato‐S,S′)diiron complexes 4a–4c with varying amounts of dimethyldioxirane (DMD) was systematically studied. The chemoselectivity of the oxidation products depended upon the substituent R (R=H, Me, 1/2 (CH2)5). For R=H, four oxidation products, 6a–6d, have been obtained. In the case of R=Me, three products, 7a–7c, were formed, and for R=1/2 (CH2)5, only complex 8 was observed. These observations are due to steric and electronic effects caused by the substituent R. Additionally, oxidation of the triiron complex 5 with DMD was performed to yield the products 9a and 9b. X‐Ray diffraction analyses were performed for 6a–6d, 7a, and 7c, as well as for 9a and 9b. The electronic properties were determined by density‐functional theory (DFT) calculations.
Cytotoxicity and Cellular Accumulation of Palladium(II) Complexes of Tetracyclines
Authors: de Paula Flávia C. S. , Guerra Wendell , Silva Iara R. , Silveira Josianne N. , Botelho Françoise Vasconcelos , Vieira Leda Q. , Pereira‐Maia Elene C.
Published: October 2008

We studied the cytotoxic effect and the uptake of PdII complexes of doxycycline (Dox), [Pd(Dox)Cl2] (1), and tetracycline (Tc), [Pd(Tc)Cl2] (2), in chronic myelogenous leukemia cells. The effect of the compounds on macrophage viability was also investigated. Compound 1 is more effective than compound 2 in inhibiting the growth of K562 cells with the IC50 values of 14.44 and 34.54 μM, respectively. There is a good correlation between cell‐growth inhibition and intracellular metal concentrations, determined by inductively coupled plasma atomic emission spectroscopy (ICP‐AES). Incubation of the cells with equitoxic concentrations of both compounds yields approximately the same intracellular Pd concentration. At the IC50 doses, intracellular concentration is ca. 33×10−16 mol/cell for both compounds 1 and 2. This suggests that more [Pd(Tc)Cl2] is needed to produce a cytotoxic effect, because it enters cells more slowly. Both compounds up to 16 μM did not affect the viability of mouse peritoneal macrophages after a 48‐h incubation. After 72 h of incubation, the IC50 values are 22 for [Pd(Dox)Cl2] and 40 μM for [Pd(Tc)Cl2]. Therefore, the cytotoxic effect in cancer cells exhibited by both compounds is higher than their effect in macrophages.
Imaging Target mRNA and siRNA‐Mediated Gene Silencing In Vivo with Ribozyme‐Based Reporters
Authors: So Min‐Kyung , Gowrishankar Gayatri , Hasegawa Sumitaka , Chung June‐Key , Rao Jianghong
Published: October 2008

Noninvasive imaging of specific mRNAs in living subjects promises numerous biological and medical applications. Common strategies use fluorescently or radioactively labelled antisense probes to detect target mRNAs through a hybridization mechanism, but have met with limited success in living animals. Here we present a novel molecular imaging approach based on the group I intron of Tetrahymena thermophila for imaging mRNA molecules in vivo. Engineered trans‐splicing ribozyme reporters contain three domains, each of which is designed for targeting, splicing, and reporting. They can transduce the target mRNA into a reporter mRNA, leading to the production of reporter enzymes that can be noninvasively imaged in vivo. We have demonstrated this ribozyme‐mediated RNA imaging method for imaging a mutant p53 mRNA both in single cells and noninvasively in living mice. After optimization, the ribozyme reporter increases contrast for the transiently expressed target by 180‐fold, and by ten‐fold for the stably expressed target. siRNA‐mediated specific gene silencing of p53 expression has been successfully imaged in real time in vivo. This new ribozyme‐based RNA reporter system should open up new avenues for in vivo RNA imaging and direct imaging of siRNA inhibition.
A Type I/Type III Polyketide Synthase Hybrid Biosynthetic Pathway for the Structurally Unique ansa Compound Kendomycin
Authors: Wenzel Silke C. , Bode Helge B. , Kochems Irene , Müller Rolf
Published: October 2008

Kendomycin is a bioactive polyketide that is produced by various Streptomyces strains. It displays strong antibiotic activities against a wide range of bacteria and exhibits remarkable cytotoxic effects on the growth of several human cancer cell lines. In this study we cloned the corresponding biosynthetic locus from the producer Streptomyces violaceoruber (strain 3844‐33C). Our analysis shows that a mixed type I/type III polyketide synthase pathway is responsible for the formation of the fully carbogenic macrocyclic scaffold of kendomycin, which is unprecedented among all of the ansa compounds that have been isolated so far. Heterologous expression of a gene set in Streptomyces coelicolor shows that 3,5‐dihydroxybenzoic acid is an intermediate in the starter unit biosynthesis that is initiated by the type III polyketide synthase. The identification of the kendomycin biosynthetic gene cluster sets the stage to study a novel chain termination mechanism by a type I PKS that leads to carbocycle formation and provides the starting material for the heterologous expression of the entire pathway, and the production of novel derivatives by genetic engineering.
A Novel Ni4 Complex Exhibiting Microsecond Quantum Tunneling of the Magnetization
Authors: Aromí Guillem , Bouwman Elisabeth , Burzurí Enrique , Carbonera Chiara , Krzystek J. , Luis Fernando , Schlegel Christoph , van Slageren Joris , Tanase Stefania , Teat Simon J.
Published: October 2008

A highly asymmetric NiII cluster [Ni4(OH)(OMe)3(Hphpz)4(MeOH)3](MeOH) (1) (H2phpz=3‐methyl‐5‐(2‐hydroxyphenyl)pyrazole) has been prepared and its structure determined by means of single‐crystal X‐ray diffraction by using synchrotron radiation. Variable‐temperature bulk‐magnetization measurements show that the complex exhibits intramolecular‐ferromagnetic interactions leading to a spin ground state S=4 with close‐lying excited states. Magnetization and high‐frequency EPR measurements suggest the presence of sizable Ising‐type magnetic anisotropy, with zero‐field splitting parameters D=−0.263 cm−1 and E=0.04 cm−1 for the spin ground state, and an isotropic g value of 2.25. The presence of both axial and transverse anisotropy was confirmed through low‐temperature specific heat determinations down to 300 mK, but no slow relaxation of the magnetization was observed by AC measurements down to 1.8 K. Interestingly, AC susceptibility measurements down to temperatures as low as 23 mK showed no indication of slow relaxation of the magnetization in 1. Thus, despite the presence of an anisotropy barrier (U≈4.21 cm−1 for the purely axial limit), the magnetization relaxation remains extremely fast down to the lowest temperatures. The estimated quantum tunneling rate, Γ>0.667 MHz, makes this complex a prime candidate for observation of coherent tunneling of the magnetization.
Geräte und Anlagen für neue Lacke mit nanoskaligem Zirkondioxid
Authors: Veith M. , Altherr A. , Klook M.
Published: October 2008

Für die Herstellung und Verarbeitung nanoskaliger Partikel wie z. B. ZrO2kann nicht immer auf Geräte, Anlagen oder Methoden nach dem Stand der Technik zurückgegriffen werden. Aus diesem Grund müssen für den Syntheseweg, von der Fällung über die Kristallisation bis zum fertigen Produkt, eigens konstruierte Anlagen bzw. speziell umgebaute Maschinen verwendet werden. Der Fokus des Beitrags liegt hierbei auf einem eigens konstruierten kontinuierlichen Autoklaven (Rohrreaktor) und einer speziell umgebauten Kugelmühle.
Herstellung von Nanostrukturen mittels Atomlagenabscheidung
Authors: Langner A. , Knez M. , Gösele U.
Published: October 2008

Die kontrollierte Manipulation von Materialien auf einer Größenskala bis in den Nanometerbereich ist heutzutage ein wesentlicher Bestandteil moderner Technologie. Dieser Übersichtsartikel behandelt eine Methode, die zum kontrollierten Dickenwachstum von Elementen und Verbindungen auf zahlreichen Substraten verwendet wird.
Polymere für Funktionale Oberflächen: Nanostrukturen und Selbstorganisation
Authors: Stamm M.
Published: October 2008

Polymere bieten eine große Vielfalt an chemischen Grundbausteinen und Architekturen, die die Werkstoffeigenschaften bestimmen. Weitgehend unabhängig von den Materialeigenschaften im Innern lassen sich durch nanoskopisch dünne Filme an der Oberfläche neue Funktionalitäten erzeugen, die die Gebrauchseigenschaften ganz entscheidend beeinflussen können. Hierbei spielt häufig nur eine nanoskopisch dünne Oberflächenschicht eine Rolle, an der die Struktur, Ordnung und Konformation der Polymere interessante Gestaltungsmöglichkeiten bieten. Prominentes Beispiel ist die Ultrahydrophobie in Verbindung mit der Selbstreinigung der Oberfläche, die durch eine Kombination von Struktur und Chemie der Oberfläche mit geeigneten Polymeren synthetisch erzeugt werden kann. Im Folgenden werden einige Beispiele von nanostrukturierten Oberflächen diskutiert, an denen durch zunehmende Organisation der Polymere unterschiedliche Funktionalitäten erzeugt werden können. Der Baukasten der Polymere bietet hier noch ungeahnte Möglichkeiten.
Einfluss der Reinigung und Funktionalisierung von Kohlenstoff‐Nanoröhren auf deren katalytische Eigenschaften in der Direct Methanol Fuel Cell‐Anode
Authors: Drillet J.‐F. , Bueb H. , Dittmeyer R. , Dettlaff‐Weglikowska U. , Roth S.
Published: October 2008

Kohlenstoff‐VulcanXC72 gilt derzeit als Standard‐Katalysatorträger in der Niedertemperatur‐Brennstoffzelle. Aufgrund seiner relativ niedrigen spezifischen Oberfläche sowie seiner Korrosionsanfälligkeit ist man zurzeit auf der Suche nach Ersatzmaterialien. In diesem Beitrag wird über den Einsatz von Kohlenstoff‐Nanoröhren als PtRu‐Katalysatorträger in der DMFC‐Anode berichtet. Nach chemischer Vorbehandlung der Kohlenstoff‐Nanoröhren in Luft bei 300 °C bzw. in konzentrierter Salpetersäure wurde eine Zellleistung von 152 bzw. 157 mW cm–2 bei einer anodischen und kathodischen Pt‐Beladung von 1 mg cm–2 ermittelt. Dies entspricht einer um ca. 10 % höheren Leistung im Vergleich zu einer Membran‐Elektroden‐Einheit (MEE) mit einer PtRu‐Vulcan‐Anode.
Nanotechnologie – Zwerge erobern den Alltag
Authors: Krug Harald F.
Published: October 2008

Die verschiedenen Bereiche der Nanotechnologie bringen neue Entwicklungen sowie neue Materialien in neuen Anwendungen mit sich und damit werden auch Mensch und Umwelt mit diesen neuen Materialien in Kontakt kommen. Wann immer die Nutzung von Chemikalien oder Nanomaterialien mit einer möglicherweise erhöhten Exposition von Mensch und Umwelt einhergeht, müssen wir aufmerksam sein und auch die Möglichkeit prüfen, ob dieser Kontakt eventuell negative Folgen haben kann. Sowohl die Gesundheit des Menschen aber auch die Erhaltung der Ökosysteme sollten dabei höchste Priorität besitzen. Daher wird seit einiger Zeit auch intensiv auf dem Gebiet der Nanotoxikologie geforscht, um die Nutzung der Nanomaterialien sicher und nachhaltig zu gestalten. Der Bericht soll einen Überblick nicht nur über die nationalen, sondern auch über die europaweiten Aktivitäten geben, die zur Nachhaltigkeit der Nanotechnologien beitragen sollen.
Polymere Nanofasern durch Elektrospinnen – Materialien für neue Anwendungen
Authors: Agarwal S. , Greiner A. , Wendorff J. H.
Published: October 2008

Vliese aus Nanofasern, die in vielfältiger Art und Weise aus verschiedensten Polymeren durch Elektrospinnen hierzu verarbeitet werden, lassen sich ebenfalls durch Elektrospinnen herstellen. Unterschiedliche Additive wie z. B. Katalysatoren, Farbstoffe, Nanopartikel, Medikamente, Viren, Bakterien etc. steigern die Funktionalität elektrogesponnener Nanofasern deutlich. Mit geeigneten Elektrospinn‐Anlagen können Nanofaservliese für verschiedene technische Anwendungen wie z. B. im Bereich der Filtration bzw. der Schutztextilien hergestellt werden. Dabei lassen sich Ergebnisse aus der Grundlagenforschung in entsprechende technische Produkte übertragen.
Polymere Nanokomposite mit anorganischen Funktionsfüllstoffen
Authors: Wagenknecht U. , Kretzschmar B. , Pötschke P. , Costa F. R. , Pegel S. , Stöckelhuber K. W. , Heinrich G.
Published: October 2008

Polymer/Partikel‐Nanokomposite sind eine Stoffklasse, die seit ca. 15 Jahren intensives Interesse in Forschung und Industrie gefunden hat. Neben erfolgreichen Anwendungen sind auch eine Reihe der ursprünglichen Erwartungen nicht erfüllt oder erfordern noch erheblichen Entwicklungsaufwand. Beispielgebend werden für drei der wichtigsten Füllstoffgruppen –Schichtsilicate, Kohlenstoff‐Nanoröhren und Layered Double Hydroxides – die Füllstoffe selbst, die Herstellung und die Eigenschaften der Nanokomposite sowie deren Anwendungspotenzial dargestellt.
Pleomorphic adenoma with predominant plasmocytoid myoepithelial cells: A diagnostic pitfall in aspiration cytology. Case report and review of the literature
Authors: Pusztaszeri Marc , Braunschweig Richard , Mihaescu Anca
Published: October 2008

Fine‐needle aspiration (FNA) biopsy of the salivary gland is a sensitive and specific diagnostic tool. However, diagnostic problems are sometimes encountered in interpreting some cases, not only in differentiating benign from malignant cases but also in the specific classification of these neoplasms. We report a case of a pleomorphic adenoma with predominant plasmocytoid myoepithelial cells arising in minor salivary glands from the hard palate in a 78‐year‐old patient, which was falsely diagnosed as a carcinoma on liquid‐based cytology (ThinPrep (TP)). The differential diagnosis of salivary gland tumors with predominant myoepithelial cells on FNA biopsy is discussed. Diagn. Cytopathol. 2009. © 2008 Wiley‐Liss, Inc.
Efficient Transfer Hydrogenation Using Iridium and Rhodium Complexes of Benzannulated N‐Heterocyclic Carbenes
Authors: Türkmen Hayati , Pape Tania , Hahn F. Ekkehardt , Çetinkaya Bekir
Published: October 2008

Benzimidazol‐2‐ylidene(NHC) derivatives of iridium(I) and rhodium(I) bearing electron‐rich and/or functional substituents R and R′ at the nitrogen atoms of the heterocycle [IrBr(cod)(NHC)] (a) or [RhBr(cod)(NHC)] (b) (R = 2,3,5,6‐tetramethylbenzyl; R′ = methoxyethyl, 1a,b; R = R′ = 2,3,5,6‐tetramethylbenzyl, 2a,b; R = pentamethylbenzyl, R′ =methoxyethyl, 3a,b; R = R′ = pentamethylbenzyl, 4a,b) were prepared. All compounds were fully characterized by 1H and 13C NMR spectroscopy, mass spectrometry (MALDI), and elemental analysis. In addition, the molecular structures of 1a, 2a, and 3a were determined by single‐crystal X‐ray diffraction studies. All of the new benzimidazol‐2‐ylidene iridium(I) and rhodium(I) complexes were found to be effective catalysts for transfer hydrogenation with iridium(I) derivative 1a showing the highest catalytic activity.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Modification of Glassy Carbon Electrode With Single‐Walled Carbon Nanotubes and α‐Silicomolybdate: Application to Sb(III) Detection
Authors: Salimi Abdollah , Korani Aazam , Hallaj Rahman , Khoshnavazi Roshan
Published: October 2008

A simple procedure was developed to prepare a glassy carbon (GC) electrode modified with single‐walled carbon nanotubes (SWCNTs) and polyoxometalate. With immersing SWCNTs modified GC electrode in silicon polyoxomolybdate (α‐SiMo12O404−) solution (direct deposition) for a short period of time (2–10 s) oxoanion adsorbed strongly and irreversibly on SWCNTs. Cyclic voltammograms of the α‐SiMo12O404− incorporated‐SWCNTs indicates three well‐defined and reversible redox couples with surface confined characteristic at wide pH range (1–7). The surface coverage (Γ) of α‐SiMo12O404− immobilized on SWCNTs was 2.14 (±0.11)×10−9 mol cm−2 indicating high loading ability of SWCNTs for polyoxometalate. The charge transfer rate constant (ks) of three redox couples of adsorbed α‐SiMo12O404− were 9.20 (±0.20), 8.02 (±0.20), and 3.70 (±0.10) s−1, respectively, indicate great facilitation of the electron transfer between α‐SiMo12O404− and CNTs. In this research the attractive mechanical and electrical characteristics of CNTs and unique properties and reactivity of polyoxometalates were combined. The modified electrode in buffer solution containing Sb(III) shows a new redox system at 0.38 V in pH 1. The voltammetric peak current increased with increasing Sb(III) concentration. The differential pulse voltammetry (DPV) technique was used for detection micromolar concentration of antimony. Furthermore, the interference effects various electroactive compounds on voltammetric response of Sb(III) were negligible. Finally the ability of the modified electrode for antimony detection in real samples was evaluated.
A Contactless Impedance Probe for Simple and Rapid Determination of the Ratio of Liquids with Different Permittivities in Binary Mixtures
Authors: Opekar František , Štulík Karel , Fišarová Michaela
Published: October 2008

Simple contactless cells with planar or tubular electrodes have been designed for measurement of the permittivity of solutions. The cells, connected to an integrated circuit of astable multivibrator, respond primarily to the capacitance component of the cell impedance, the multivibrator frequency depends in a defined manner on the solution permittivity and is readily used as the analytical signal in determinations of the ratios of components in binary liquid mixtures; water solution of methanol, ethanol and dioxane have been tested. The response of the cell with planar electrodes satisfies well the simple theoretical model and both the cells provide results with a sufficient sensitivity, a low LOD value (units of %vol) and a good precision (around 1%rel). The cell simplicity, small dimensions, long‐term stability and the possibility of powering them from a battery make them suitable for hand‐held meters. As an example of application in practice, the content of ethanol was determined in the car fuel petrol.
Preparation of GOD/Sol‐Gel Silica Film on Prussian Blue Modified Electrode for Glucose Biosensor Application
Authors: Liang Ru‐Ping , Jiang Jing‐Li , Qiu Jian‐Ding
Published: October 2008

A novel amperometric glucose biosensor was fabricated by in situ incorporating glucose oxidase (GOD) within the sol‐gel silica film on a Prussian blue (PB) modified electrode. The method is simple and controllable, which combined the merits of in situ immobilizing biomolecules in sol‐gel silica film by electrochemical method and the synergic catalysis effects of PB and GOD molecules. Scanning electron microscopy (SEM) showed that the GOD/sol‐gel silica film was homogeneous with a large number of three‐dimensional nanopores, which not only enhanced mass transport, but also maintained the active configuration of the enzyme molecule and prevented the leakage of enzyme, therefore improved the stability and sensitivity of the biosensor. The fabricated biosensor showed fast response time (10 s), high sensitivity (26.6 mA cm−2 M−1), long‐term stability, good suppression of interference, and linear range of 0.01 mM–5.8 mM with a low detection limit of 0.94 μM for the detection of glucose. In addition, the biosensor was successfully applied to determine glucose in human serum samples.
Direct Electrochemistry of Hemoglobin on Single‐Walled Carbon Nanotubes Modified Carbon Ionic Liquid Electrode and Its Electrocatalysis
Authors: Sun Wei , Li Xiaoqing , Zhai Ziqin , Jiao Kui
Published: October 2008

In this article we report on the fabrication of a carbon ionic liquid electrode (CILE) by using a room temperature ionic liquid of 1‐butyl‐3‐methylimidazolium hexafluorophosphate (BMIMPF6) as binder. It was further modified by single‐walled carbon nanotubes (SWCNTs) to get a SWCNTs modified CILE denoted as SWCNTs/CILE. The redox protein of hemoglobin (Hb) was further immobilized on the surface of SWCNTs/CILE with the help of Nafion film. UV‐vis and FT‐IR spectra indicated that the immobilized Hb retained its native conformation in the composite film. The direct electrochemistry of Hb on the SWCNTs/CILE was carefully studied in pH 7.0 phosphate buffer solution (PBS). Cyclic voltammetric results indicated that a pair of well‐defined and quasireversible voltammetric peaks of Hb heme Fe(III)/Fe(II) was obtained with the formal potential (E°') at −0.306 V (vs. SCE). The electrochemical parameters such as the electron transfer coefficient (α), the electron transfer number (n) and the apparent heterogeneous electron transfer rate constant (ks) were calculated as 0.34, 0.989 and 0.538 s−1, respectively. The fabricated Hb modified electrode showed good electrocatalytic ability to the reduction of trichloroacetic acid (TCA) in the concentration range from 20.0 to 150.0 mmol/L with the detection limit of 10.0 mmol/L (3σ).