bluuebunny/crossref_metadata_2025 huggingface dataset:
Brownian dynamics study of the association between the 70S ribosome and elongation factor G
Authors: Długosz Maciej , Huber Gary A. , McCammon J. Andrew , Trylska Joanna
Published: March 2011

Protein synthesis on the ribosome involves a number of external protein factors that bind at its functional sites. One key factor is the elongation factor G (EF‐G) that facilitates the translocation of transfer RNAs between their binding sites, as well as advancement of the messenger RNA by one codon. The details of the EF‐G/ribosome diffusional encounter and EF‐G association pathway still remain unanswered. Here, we applied Brownian dynamics methodology to study bimolecular association in the bacterial EF‐G/70S ribosome system. We estimated the EF‐G association rate constants at 150 and 300 mM monovalent ionic strengths and obtained reasonable agreement with kinetic experiments. We have also elucidated the details of EF‐G/ribosome association paths and found that positioning of the L11 protein of the large ribosomal subunit is likely crucial for EF‐G entry to its binding site. © 2011 Wiley Periodicals, Inc. Biopolymers 95: 616–627, 2011.
Development and validation of a RP‐HPLC method for stability‐indicating assay of gemifloxacin mesylate including identification of related substances by LC‐ESI‐MS/MS, 1H and 13C NMR spectroscopy
Authors: Nageswara Rao R. , Naidu Ch. Gangu , Prasad K. Guru , Narasimha R.
Published: March 2011

A validated stability indicating RP‐HPLC assay of gemifloxacin mesylate was developed by separating its related substances on an Inertsil‐ODS3V‐C18 (4.6 × 250 mm; 5 μm) column using 0.1% trifluoroaceticacid (pH 2.5) and methanol as a mobile phase in a gradient elution mode at a flow rate of 1.0 mL/min at 27°C. The column effluents were monitored by a photodiode array detector set at 287 nm. The method was validated in terms of accuracy, precision and linearity as per ICH guidelines. Forced degradation of gemifloxacin (GFX) was carried out under acidic, basic, thermal, photolysis and peroxide conditions and the degradation products were separated and characterized by ESI‐MS/MS, 1H and 13C NMR spectroscopy. The method was successfully applied to the analysis of bulk drugs and the recoveries of gemifloxacin and impurities were in the range of 97.60–102.90 and 96.99–102.10%, respectively. No previous reports were found in the literature on identification of degradation products of gemifloxacin. Copyright © 2011 John Wiley & Sons, Ltd.
Towards autonomic management for Cloud services based upon volunteered resources
Authors: Caton Simon , Rana Omer
Published: March 2011

Many research institutions and Universities own computational capacity that is not effectively utilized, thereby providing an opportunity for such institutions to use such capacity to offer Cloud services (to both internal and external users). However, the unreliability and unpredictability of these resources mean that their use in the context of a Service Level Agreement (SLA) is high risk, leading to a reduction in reputation as well as economic penalties in case of SLA violation. We propose a methodology that addresses the issues of unreliability and unpredictability such that Cloud software services could be hosted upon volunteered resources. To enable the harnessing of these resources we rely on autonomic fault management techniques that allow such systems to independently adapt the resources they use based upon their perception of individual resource reliability. Using our approach we were able to scale out the backend infrastructure of the Cloud service elastically (min 30thinspaces per worker), opportunistically and autonomically. We address two key questions in this article: can a campus volunteer infrastructure be used in Cloud provisioning? What measures are necessary in order to ensure reliability at the resource level? Copyright © 2011 John Wiley & Sons, Ltd.
Steric and Chain Length Effects in the (${\sqrt {(3)} }$×${\sqrt {(3)} }$)R30° Structures of Alkanethiol Self‐Assembled Monolayers on Au(111)
Authors: Torres Edmanuel , Blumenau Alexander T. , Biedermann P. Ulrich
Published: March 2011

The translational and orientational potential energy surfaces (PESs) of n‐alkanethiols with up to four carbon atoms are studied for (${\sqrt {(3)} }$×${\sqrt {(3)} }$)R30° self‐assembled monolayers (SAMs). The PESs indicate that methanethiol may form SAM structures that are not accessible for long‐chain thiols. The tilt of the thiol molecules is determined by a compromise between the preferred binding geometry at the sulfur atom and the steric requirements of the alkane chains. The AuS bond lengths, offset from the bridge position (brg), and the AuSC bond angles result in tilt angles of the SC bond in the range of 55–60°. As DFT/generalized gradient approximation systematically underestimates chain–chain interactions, the binding energies are corrected by comparison to MP2 interaction energies of alkane dimers in SAM‐like configurations. The resulting thiol binding energies increase by approximately 1 kcal mol−1 per CH2 group, which results in a substantial stabilization of long‐chain SAMs due to chain–chain interactions. Furthermore, as the chain length increases, the accessible range of backbone tilt angles is constrained due to steric effects. The combination of these two effects may explain why SAM structures with long‐chain thiols exhibit higher order in experiments. For each thiol two favorable SAM structures are found with the sulfur head group at the fcc‐brg and hcp‐brg positions, respectively. These domains may coexist in thermal equilibrium. In combination with the symmetry of the gold (111) surface, this raises the possibility of up to six different domains on single‐crystal terraces. Reconstructions by an adatom or vacancy of ethanethiol SAMs with (${\sqrt {(3)} }$×${\sqrt {(3)} }$)R30° lattice are also studied using PES scans. The results indicate that adsorption of thiols next to a vacancy is favorable and may lead to point defects inside SAMs.
Role of Internalization Process in Defining the Relationship between ISO 14001 Certification and Corporate Environmental Performance
Authors: Qi Guoyou , Zeng Saixing , Li Xiaodong , Tam Chiming
Published: March 2011

The relationship between ISO 14001 certification and corporate environmental performance has become an important research topic in recent years. Based on the internalization process of ISO 14001 (the process that consolidates and embeds a firm's beliefs, attitudes, and values into its management and employees), this paper examines how internalization can impact on the corporate environmental performance. It is found that the internalization process of ISO 14001 serves an important role in mediating the relationship between ISO 14001 certification and environmental performance. The results also reveal that the internal motivation is the main driving force of internalizing ISO 14001. Copyright © 2011 John Wiley & Sons, Ltd and ERP Environment.
Effects of carrier frequency offset on the average effective SNR and the average BER for asynchronous MC‐CDMA uplink systems with a guard period
Authors: Ko Kyunbyoung , Woo Choongchae
Published: March 2011

This paper presents an analysis of asynchronous multicarrier‐code division multiple access (MC‐CDMA) systems over frequency‐selective multipath fading channels when the carrier frequency offsets (CFOs) of all users are random variables and the frequency offset for the desired user is compensated. The effect of residual CFO on the average bit error rate (BER) is evaluated by the semi‐analytical method, then the approximated BER performance is obtained as a closed‐form expression. Moreover, the signal‐to‐noise ratio (SNR) loss caused by residual CFO is evaluated. Derived results show that the performance degradation due to residual frequency offset is negligible if the estimation error of CFO for the desired user is less than the normalized value of 10−1. Copyright © 2011 John Wiley & Sons, Ltd.
Lessons learned from successful Papanicolaou cytology cervical cancer prevention in the socialist republic of Vietnam
Authors: Suba Eric J. , Raab Stephen S.
Published: March 2011

In 1996, we documented that the burden of cervical cancer in Vietnam was associated with troop movements during the Vietnam War. Subsequently, establishment of Papanicolaou screening in southern Vietnam was associated with reductions in cervical cancer incidence from 29.2/100,000 in 1998 to 16/100,000 in 2003. This is one of the first English‐language reports of a real‐world cervical cancer prevention effort associated with a decisive impact on health outcomes in a contemporary developing country. Lessons learned: if our ideological commitment is to improve health outcomes as rapidly as possible among as many people as possible, then Papanicolaou screening (with or without HPV or visual screening) must be implemented without further delay in any setting where cervical screening is appropriate but unavailable; consideration must be given to HPV vaccination after, rather than before, full coverage of target demographic groups by screening services has been achieved and/or the possibility has been excluded that HPV vaccination may be ineffective for cancer prevention. Competing ideological commitments engender imprudent yet commercially useful alternative strategies prone to decelerate global reductions in mortality by suppressing the more‐rapid uptake of less‐expensive open‐source technology in favor of the less‐rapid uptake of more‐expensive proprietary technologies with uncertain real‐world advantages and unfavorable real‐world operational limitations. Global cervical cancer prevention efforts will become more effective if global health leaders, including the Bill & Melinda Gates Foundation, embrace an ideological commitment to improving health outcomes as rapidly as possible among as many people as possible and assimilate the policy implications of that commitment. Diagn. Cytopathol. 2011. © 2011 Wiley‐Liss, Inc.
T‐cell synapse formation depends on antigen recognition but not CD3 interaction: Studies with TCR:ζ, a candidate transgene for TCR gene therapy
Authors: Roszik János , Sebestyén Zsolt , Govers Coen , Guri Yakir , Szöőr Árpád , Pályi‐Krekk Zsuzsanna , Vereb György , Nagy Peter , Szöllősi János , Debets Reno
Published: March 2011

T‐cell receptors (TCRs) can be genetically modified to improve gene‐engineered T‐cell responses, a strategy considered critical for the success of clinical TCR gene therapy to treat cancers. TCR:ζ, which is a heterodimer of TCRα and β chains each coupled to complete human CD3ζ, overcomes issues of mis‐pairing with endogenous TCR chains, shows high surface expression and mediates antigen‐specific T‐cell functions in vitro. In the current study, we further characterized TCR:ζ in gene‐engineered T cells and assessed whether this receptor is able to interact with surface molecules and drive correct synapse formation in Jurkat T cells. The results showed that TCR:ζ mediates the formation of synaptic areas with antigen‐positive target cells, interacts closely with CD8α and MHC class I (MHCI), and co‐localizes with CD28, CD45 and lipid rafts, similar to WT TCR. TCR:ζ did not closely associate with endogenous CD3ε, despite its co‐presence in immune synapses, and TCR:ζ showed enhanced synaptic accumulation in T cells negative for surface‐expressed TCR molecules. Notably, synaptic TCR:ζ demonstrated lowered densities when compared with TCR in dual TCR T cells, a phenomenon that was related to both extracellular and intracellular CD3ζ domains present in the TCR:ζ molecule and responsible for enlarged synapse areas.
IKK‐β‐mediated myeloid cell activation exacerbates inflammation and inhibits recovery after spinal cord injury
Authors: Kang Junghee , Jiang Mei Hua , Min Hyun Jung , Jo Eun‐Kyeong , Lee Soojin , Karin Michael , Yune Tae Young , Lee Sung Joong
Published: March 2011

Traumatic spinal cord injury (SCI) is followed by massive infiltration and activation of myeloid cells such as neutrophils and macrophages, but the functions of these cells are controversial. In this study, our objective was to elucidate the in vivo role of a signaling pathway involved in activation of these innate immune cells in SCI using myeloid cell‐specific IκB kinase (IKK)‐β conditional knockout (${\rm {ikk}}{\rm {\beta}}^{\Delta mye}$ ) mice. In these mice, the ikkβ gene has been specifically deleted from myeloid cells, compromising their in vivo IKK/NF‐κB‐dependent activation. We found that ${\rm {ikk}}{\rm {\beta}}^{\Delta mye}$ mice had significantly reduced neutrophil and macrophage infiltrations after SCI compared to ikkβ+/+ controls. SCI‐induced proinflammatory gene expression was also reduced in ${\rm {ikk}}{\rm {\beta}}^{\Delta mye}$ mice. Reduced neuroinflammation in ${\rm {ikk}}{\rm {\beta}}^{\Delta mye}$ mice was accompanied by attenuated neuronal loss and behavioral deficits in motor activity. In addition, the SCI‐induced expression of CXC ligand 1 was reduced in ${\rm {ikk}}{\rm {\beta}}^{\Delta mye}$ mice, which may be responsible for the reduced neutrophil infiltration in these mice. Our data demonstrate that IKK‐β‐dependent myeloid cell activation potentiates neuroinflammation and neuronal damage after SCI.
Translocation of an antibody transgene requires AID and occurs by interchromosomal switching to all switch regions except the mu switch region
Authors: Shansab Maryam , Eccleston Jennifer M. , Selsing Erik
Published: March 2011

Immunoglobulin (Ig) class switch recombination (CSR) occurs most often by intrachromosomal recombinations between switch (S) regions located on a single chromosome, but it can also occur by interchomosomal recombinations between Ig heavy chain (Igh) S regions located on chomosomal homologs. Interchromosomal recombinations have also been found between chromosomes that are not homologs; examples are Igh/c‐myc and Igh/transgene translocations. Most, but not all, studies have indicated that activation‐induced cytidine deaminase (AID) is important in Igh/c‐myc translocations. The role of AID has not been determined for Igh/transgene translocations. We now show that the majority of Igh/transgene translocations between non‐homologs from an Ig transgenic mouse are dependent on AID, but we also find a small number of these translocations that can occur in the absence of AID. Surprisingly, our results also indicate that, although Sγ switch sequences in the endogenous Igh locus participate in chromosomal translocations with the non‐homolog transgene‐bearing chromosome, Sμ switch sequences do not. This contrasts with the fact that both endogenous Sμ and Sγ sequences participate in intrachromosomal CSR. Our findings suggest the operation of a regulatory mechanism that can differentially control the accessibility of Sμ and Sγ regions for non‐homolog translocations even when both are accessible for intrachromosomal recombination.
Increased apoptosis, curtailed expansion and incomplete differentiation of CD8+ T cells combine to decrease clearance of L. monocytogenes in old mice
Authors: Smithey Megan J. , Renkema Kristin R. , Rudd Brian D. , Nikolich‐Žugich Janko
Published: March 2011

Aging is accompanied by altered immunity, resulting in a variable state of poorly understood immunodeficiency. While both the numbers and the functionality of naïve T cells are decreased by aging, the impact of these changes upon immune defense against bacterial pathogens in vivo remains understudied. Using a model of Listeria monocytogenes (Lm), where the primary CD8+ T‐cell response is critically important for immune defense, we show that C57BL/6 (B6) mice exhibit an age‐dependent reduction in survival, with delayed bacterial clearance in old animals. Kinetic analysis of antigen‐specific CD8+ T‐cell expansion showed that CD8+ effectors begin dividing at the same time in old and adult mice, but that the proliferative burst remained incomplete during discrete windows of time and was coupled with increased effector apoptosis in old mice. Further, antilisterial CD8+ T cells in old mice showed altered expression of key phenotypic and effector molecules and diminished polyfunctionality, measured by the ability to simultaneously produce multiple effector molecules. These results suggest that defects in functional maturation of CD8+ cells in aged mice, compounded by (or perhaps coupled to) their reduced expansion in response to infection, yield effector CD8+ T‐cell populations insufficient in size and capability to effectively clear newly encountered intracellular pathogens.
Altered purinergic signaling in CD73‐deficient mice inhibits tumor progression
Authors: Yegutkin Gennady G. , Marttila‐Ichihara Fumiko , Karikoski Marika , Niemelä Jussi , Laurila Juha P. , Elima Kati , Jalkanen Sirpa , Salmi Marko
Published: March 2011

CD73/ecto‐5′‐nucleotidase dephosphorylates extracellular AMP into adenosine, and it is a key enzyme in the regulation of adenosinergic signaling. The contribution of host CD73 to tumor growth and anti‐tumor immunity has not been studied. Here, we show that under physiological conditions CD73‐deficient mice had significantly elevated ATPase and ADPase activities in LN T cells. In a melanoma model, the growth of primary tumors and formation of metastasis were significantly attenuated in mice lacking CD73. Among tumor‐infiltrating leukocytes there were fewer Tregs and mannose receptor‐positive macrophages, and increased IFN‐γ and NOS2 mRNA production in CD73‐deficient mice. Treatment of tumor‐bearing animals with soluble apyrase, an enzyme hydrolyzing ATP and ADP, significantly inhibited tumor growth and accumulation of intratumoral Tregs and mannose receptor‐positive macrophages in the WT C57BL/6 mice but not in the CD73‐deficient mice. Pharmacological inhibition of CD73 with α,β‐methylene‐adenosine‐5′‐diphosphate in WT mice retarded tumor progression similarly to the genetic deletion of CD73. Together these data show that increased pericellular ATP degradation in the absence of CD73 activity in the host cells is a novel mechanism controlling anti‐tumor immunity and tumor progression, and that the purinergic balance can be manipulated therapeutically to inhibit tumor growth.
Antibody – Fc receptor interactions in protection against intracellular pathogens
Authors: Joller Nicole , Weber Stefan S. , Oxenius Annette
Published: March 2011

Intracellular pathogen‐specific antibodies (Abs) can contribute to host protection by a number of different mechanisms. Ab opsonization of pathogens residing outside a host cell can prevent infection of target cells either via neutralization of the critical surface epitopes required for host cell entry, complement‐mediated degradation, or via subsequent intracellular degradation. In the case of intracellular localization, Abs can bind to infected cells and thus mark them for destruction by Fc receptor (FcR)‐bearing effector cells. This review focuses on the protective role of Abs against intracellular bacteria and parasites involving FcR interactions that modulate the intracellular trafficking of the pathogen, the ability of FcRs to interfere with the establishment of an intracellular replicative niche and the involvement of FcRs to modulate pathogen‐specific T‐cell responses.
Ontogeny of thymic cortical epithelial cells expressing the thymoproteasome subunit β5t
Authors: Ripen Adiratna Mat , Nitta Takeshi , Murata Shigeo , Tanaka Keiji , Takahama Yousuke
Published: March 2011

Proteasomes are responsible for generating peptides presented by class I MHC molecules of the immune system. β5t, a recently identified proteasome component, is specifically expressed in thymic cortical epithelial cells (cTECs) and plays a pivotal role in generating an immunocompetent repertoire of class I MHC‐restricted CD8+ T cells. Here, we report that β5t is detectable in the thymus as early as E12.5 mouse embryos. We also found that β5t expression in cTECs was detectable in mice deficient for RelB or Rag2, indicating that β5t in cTECs is expressed in the absence of thymic medulla formation or thymocyte development beyond the CD4−CD8− stage. β5t expression in the embryonic thymus was not detectable in Foxn1‐deficient nude mice, although its expression was not reduced in mice deficient for both CCR7 and CCR9, in which fetal thymus colonization by leukocytes is defective. These results indicate that β5t expression in cTECs is dependent on Foxn1 but independent of thymocyte crosstalk or thymic medulla formation.
Ph3PAuNTf2 as a Superior Catalyst for the Selective Synthesis of 2H‐Chromenes: Application to the Concise Synthesis of Benzopyran Natural Products
Authors: Lykakis Ioannis N. , Efe Christina , Gryparis Charis , Stratakis Manolis
Published: March 2011

Ph3PAuNTf2 (≈1 mol‐%) catalyzes the selective cycloisomerization of substituted aryl propargyl ethers into 2H‐chromenes in excellent yields. Benzofuran byproducts are formed only in the case of electron‐deficient arenes, in up to 7 % relative yield. The Ph3PAuNTf2‐catalyzed cyclization of aryl propargyl ethers was applied as a key step to the concise synthesis of the naturally occurring benzopyrans seselin, xanthyletin, precocenes I and II, 8‐(3′,3′‐dimethylallyl)wenteria chromene, and 2,2‐dimethyl‐8‐prenylchromene‐6‐propenoic acid.
Determination of hydrazines by chip electrophoresis with contactless conductivity detection
Authors: Kumar Ashwini , Burns Jacob , Hoffmann Werner , Demattio Horst , Malik Ashok Kumar , Matysik Frank‐Michael
Published: March 2011

In this report, a new approach for the fast determination of hydrazine compounds (hy) in complex matrices is presented. The experimental protocol is based on poly(methylmethacrylate) (PMMA) microchip separations with contactless conductivity detection using a compact portable device, which integrates all separation and detection components. Three hy (hydrozine (Hy), methylhydrazine (MH), and 1,1‐dimethylhydrazine (UDMH)) were separated within <30 s at a separation voltage of 3.8 kV using a L(−)‐histidine/2‐(N‐morpholinoethanesulfonic acid) (His/MES) buffer (25:50 mM, pH 5.87). The contactless conductivity detection enables detection limits for Hy, MH, and UDMH of 11.9, 35.5, and 337.8 ng/mL, respectively, with linear concentration dependence up to 10 μg/mL. In complex matrices such as soil samples or river water, interferences were eliminated by implementing ultrasound‐assisted headspace single‐drop microextraction of hy under strongly alkaline conditions, using an aqueous drop of His/MES buffer as the extractant phase. The incorporation of this miniaturized sample preparation step led to improved limits of detection for Hy, MH, and UDMH of 6.5, 15.3, and 11.4 ng/mL, respectively. The overall protocol demonstrates a promising approach for interfacing chip electrophoresis with real‐world applications.
Determination of muscle relaxants pancuronium and vecuronium bromide by capillary electrophoresis with capacitively coupled contactless conductivity detection
Authors: Petrů Klára , Jáč Pavel , Lužová Veronika , Kuneš Jiří , Polášek Miroslav
Published: March 2011

A novel capillary electrophoretic method for the separation of pancuronium (PM) and vecuronium (VM) ions utilizing capacitively coupled contactless conductivity detection was devised and validated. The separation was carried out in bare fused‐silica capillaries (50 μm id, 75/45 cm) at 25°C. Optimal BGE was 50 mM borate buffer of pH 9.5 containing 12.5 mg/mL of (2‐hydoxypropyl)‐γ‐CD. The samples were injected hydrodynamically at 1000 mbar for 3 s. Separation was performed at +30 kV. Under such conditions the PM and VM were base‐line resolved and the separation took <4 min. For quantification phenyltrimethylammonium iodide was used as internal standard. Calibration curves were linear for both pancuronium bromide (PMB) and vecuronium bromide (VMB) in the range 25–250 μg/mL with r>0.9968. The limits of detection were 7 and 6 μg/mL for PMB and VMB, respectively. The accuracy tested by recovery experiment at three concentration levels of added PMB and VMB was satisfactory (95.7–102.7%, n=3, with RSD <2.61%). The method was successfully applied to the assay of PMB and VMB in commercial injection solutions.
Analysis of polyphenols in white wine by CZE with amperometric detection using carbon nanotube‐modified electrodes
Authors: Moreno Mónica , Arribas Alberto Sánchez , Bermejo Esperanza , Zapardiel Antonio , Chicharro Manuel
Published: March 2011

A method for the simultaneous detection of five polyphenols (caffeic, chlorogenic, ferulic and gallic acids and (+)‐catechin) by CZE with electrochemical detection was developed. Separation of these polyphenols was performed in a 100 mM borate buffer (pH 9.2) within 15 min. Under optimized separation conditions, the performance of glassy carbon (GC) electrodes modified with multiwalled carbon nanotube layer obtained from different dispersions was examined. GC electrode modified with a dispersion of multi‐walled carbon nanotubes (CNT) in polyethylenimine has proven to be the most suitable CNT‐based electrode for its application as amperometric detector for the CZE separation of the studied compounds. The excellent electrochemical properties of this electrode allowed the detection of the selected polyphenols at +200 mV and improved the efficiency and the resolution of their CZE separation. Limits of detection below 3.1 μM were obtained with linear ranges covering the 10−5 to 10−4 M range. The proposed method has been successfully applied for the detection (ferulic, caffeic and gallic acids and (+)‐catechin) and the quantification (gallic acid and (+)‐catechin) of polyphenols in two different white wines without any preconcentration step. A remarkable signal stability was observed on the electrode performance despite the presence of potential fouling substances in wine.
Remediation of vehicle wash sediments contaminated with hydrocarbons: A field demonstration
Authors: Karthikeyan R. , Kulakow P.A. , Leven B.A. , Erickson L.E.
Published: March 2011

Military training reservations contain vehicle wash facilities where combat vehicles and other equipment are washed after field maneuvers. During this process, sediments containing significant concentrations of petroleum hydrocarbons accumulate in concrete sedimentation basins. Conventional treatment methods to decontaminate these sediments include landfill disposal or land application. However, vegetative remediation systems may offer a cost‐effective alternative. A phytoremediation design that reduces petroleum hydrocarbons to acceptable levels and is simple to manage was developed for the Central Vehicle Wash Facility at Fort Riley, Kansas. Two treatments using vegetation and fertilizer were compared to a treatment of fertilizer and no vegetation in a 3‐year study. Initial hydrocarbon concentrations, determined as total petroleum hydrocarbons, averaged about 800 mgTPH/kgsoil. All treatments resulted in reductions in total petroleum hydrocarbon concentrations of about 75% after 1 year, suggesting that hydrocarbons in the motor vehicle wash sediments have high biodegradability. Although no significant differences in hydrocarbon degradation were observed among treatments, the benefits of establishing vegetation to cover sediments during treatment suggests phytoremediation as a useful low‐cost tool to manage similar hydrocarbon impacted vehicle wash sediments. © 2011 American Institute of Chemical Engineers Environ Prog, 2012
Combustion properties of asphalt binder containing flame retardant
Authors: Xu Tao , Huang Xiaoming
Published: March 2011

Combustion characteristics of asphalt binder containing flame retardant (magnesium hydroxide, MH) were investigated using thermogravimetry and Fourier transform infrared spectrometer, and multistage combustion model of asphalt binder was developed. The results indicate that the combustion processes of asphalt binder and MH‐modified asphalt binder both include three main sequential stages. But with the MH concentration increase, the release amount of flammable volatiles is reduced, and the asphalt binder ignition time is delayed. Asphalt binder thermal stability is improved by incorporation of MH. At the same MH concentration, the kinetics parameters increase from the first to third stage. But in each stage, the kinetics parameters exhibit an increase trend in the first stage as the MH content increases, but in the second and third stages, the kinetics parameters show a trend of first increase and then decrease. Furthermore, the parameters reach the maximum at the concentration of around 20% by weight. This concentration may be appropriate for flame‐retarding asphalt binder. It is concluded that MH may be used as a new kind of environment‐friendly flame retardant for asphalt binder, and the developed thermal analysis kinetics model can be employed to evaluate the combustion characteristics of asphalt binder. Copyright © 2011 John Wiley & Sons, Ltd.
Signal Extraction and Forecasting of the UK Tourism Income Time Series: A Singular Spectrum Analysis Approach
Authors: Beneki Christina , Eeckels Bruno , Leon Costas
Published: March 2011

We present and apply singular spectrum analysis (SSA), a relatively new, non‐parametric and data‐driven method for signal extraction (trends, seasonal and business cycle components) and forecasting of UK tourism income. Our results show that SSA slightly outperforms SARIMA and time‐varying‐parameter state space models in terms of root mean square error, mean absolute error and mean absolute percentage error forecasting criteria. Copyright © 2011 John Wiley & Sons, Ltd.
Wind parks in the German Bight – a challenge for geotechnics
Authors: Gudehus Gerd
Published: March 2011

The foundations for offshore wind energy plants (OWEP) in the German Bight, with water depths of up to 30 m, are a challenge. Waves more than 20 m high can turn over meters of sandy ground, they tilt and lift embedded structures and can lead to capsizing. The sand can be re‐consolidated by normal waves, and some foundations right themselves and settle. This is due to the material properties of sand, which cannot easily be explained and can only partly be quantified. Some mechanisms of OWEP foundations can be observed in model tests, others in field tests and pilot plants. Scenarios with extreme waves require physically sound methods; code methods do not suffice. Experience with offshore production platforms cannot simply be transferred and is anyway often kept secret. Thus one has to break new ground for planning, building and maintenance of OWEP foundations.

Windparks in der deutschen Bucht – Eine Herausforderung für die Geotechnik. Die Gründung von Offshore‐Windenergie‐ Anlagen (OWEA) in bis zu 30 m tiefen Bereichen der Deutschen Bucht ist schwierig. Über 20 m hohe Wellen wühlen den sandigen Grund metertief auf, sie verkanten und heben Tragwerke in ihm, das kann zum Kentern führen. Bei normalen Wellen kann der Sand sich wieder verdichten, manche Gründungen richten sich wieder auf und sacken ein. Dies beruht auf Materialeigenschaften von Sand, die sich nicht einfach erklären und nur teilweise quantifizieren lassen. Einige Mechanismen mit OWEAGründungen kann man in Modellversuchen erkennen, andere in Großversuchen und Pilotanlagen. Für Szenarios mit Extremwellen braucht man physikalisch fundierte Methoden, Standardverfahren genügen nicht. Erfahrungen mit Offshore‐Plattformen kann man nur bedingt übernehmen, zumal Überraschungen oft verschwiegen werden. So muss man beim Planen, Bauen und Erhalten flacher und tiefer OWEA‐Gründungen Neuland erschließen.
Kolkschutz für Offshore‐Windenergieanlagen in der Nordsee
Authors: Heerten Georg , Peters Karsten
Published: March 2011

Mit der fortschreitenden Errichtung von Windenergieanlagen im Offshore‐Bereich der Nordsee rücken Fragen der langfristigen Standsicherheit dieser Anlagen in den Blickpunkt. Aufwändige Gründungsstrukturen in Wassertiefen von 10 bis 60 m sind ein erheblicher Kostenfaktor gegenüber Anlagen an Land. Fragen der Kolkentwicklung und mögliche Kolkschutzmaßnahmen sind zu untersuchen und zu lösen. Gegenüber traditionellen, aus mineralischen Komponenten geschütteten Kolkschutzvarianten finden Geokunststofflösungen zunehmend Beachtung, da sie einerseits den Einsatz örtlich anstehenden Bodenmaterials erlauben, vergleichsweise einfach und sicher einzubauen sind und andererseits keine Beschädigungen von Kabelzuführungen und Korrosionsschutz bei Stahlbauelementen der Anlagen zu befürchten sind. Der Beitrag berichtet über bisherige Erfahrungen zu Kolken und Kolkschutz bei Offshore‐Anlagen in der Nordsee sowie über den Stand der Technik der Bemessung, des Füllens und des Einbaus von Sandcontainern aus Vliesstoffen im Gründungsbereich von Offshore‐Windenergieanlagen (OWEAs) und nimmt Bezug auf schon ausgeführte Untersuchungen.

Scour protection for offshore wind energy generators in the North Sea. The increasing erection of offshore wind energy generators in the North Sea raises questions about the long‐term stability of such structures. Extensive foundation structures in water depths of 10 to 60 m are a significant cost factor compared to land installation. Questions about scour development and measures to protect against scour need to be investigated and solved. In contrast to traditional scour protection provided by tipping mineral components, geotechnical plastics are of increasing interest, because they permit the use of undisturbed ground on the site, are relatively simple and safe to install and also no damage to cable entries or corrosion protection of steel structures needs to be worried about. The article reports on experience so far with scour and scour protection for offshore facilities in the North Sea and the state of the technology in the design, filling and installation of sand containers made of geotextiles around the foundations of offshore wind energy facilities and also refers to investigations already performed.
Vibrex‐/Gürtelrüttlerpfähle – Anwendung in Polen
Authors: Świniański Jerzy , Wehr Jimmy
Published: March 2011

Für die Erweiterung einer Raffinerie kamen erstmals in Polen Vibrex‐/Gürtelrüttlerpfähle zum Einsatz. Die Raffinerie liegt im Mündungsbereich eines Flusses und die Baugrundverhältnisse sind entsprechend schwierig. Sandiger Untergrund ist mit drei Schichten organischer Sedimente bis in eine Tiefe von maximal 18 bis 22 m angesprochen worden. Alle empfindlichen und schweren Gebäude und Anlagenteile sollten tief auf Pfählen gegründet werden, da die zulässigen Setzungen vom Bauherrn auf maximal 25 mm begrenzt wurden.

Vor den eigentlichen Pfahlarbeiten wurden Pfahlversuche mit Erschütterungsmessungen ausgeführt. Statische Probebelastungen haben eine fast lineare Steifigkeit gezeigt. Bis 3.000 kN konnten nur zulässige Setzungen und keine Grenzlast nachgewiesen werden; die Pfahltragfähigkeiten sind deutlich größer als die zulässigen Lasten. Insgesamt wurden über 3.180 Pfähle (Vibrex‐, Schneckenbohrpfähle und MESI‐Mikropfähle) mit Längen von 15 bis 27 m ausgeführt. Darunter waren rund 1.440 Vibrexpfähle, die mit Gürtelrüttler hergestellt wurden. Die Vibrexpfähle konnten über die ganze Pfahllänge bewehrt werden, was für hohe Anlagenteile mit großen Zugkräften, z.B. Kamine, von großer Bedeutung war.

Vibrex‐/Belt Vibrator Piles – application in Poland. For the capacity extension of a Polish refinery, Vibrex‐/belt vibrator piles have been executed in Poland for the first time. Complicated soil conditions were encountered consisting of three organic layers positioned in a depth of up to 22 m in sandy soils. Due to the client's limitation of the settlements to 25 mm, all heavy buildings had to be founded on piles. Pile vibration measurements have been executed prior to the works. Static load tests showed a linear stiffness and no ultimate load up to 3,000 kN. Over 3,180 Piles (Vibrex, CFA and MESI) with a length of 15 to 27 m have been executed, 1,440 thereof as Vibrex piles executed with a belt vibrator. They could be reinforced over their total length, which was of importance due to objects with big tension loads like chimneys.
Polyoxometalate‐Incorporated Supramolecular Self‐Assemblies: Structures and Functional Properties
Authors: Yan Yi , Wu Lixin
Published: March 2011

As a family of functional inorganic clusters, polyoxometalates (POMs) were introduced into hybrid self‐assemblies with the assistance of the supramolecular interaction with diverse organic cationic molecules, which reinforced both the processibility and functionality of the POMs. This method not only improved the surface properties of the POMs, but also provided excellent amphiphilic building blocks for the construction of advanced self‐assembled nanostructures. In this review, we summarize the fundamental aspects of surfactant‐encapsulated POMs (SEPs) and the most recent progress in potential applications of SEPs and the related POM‐containing systems (hybrids composed of POMs and polymers and other cationic molecules beyond surfactants). The functionalization of such organic/inorganic hybrids in self‐assembled systems is also described. Furthermore, perspectives regarding self‐assemblies and possible applications of POM complexes with synergetic interactions between organic and inorganic components are outlined.
Convergent Total Synthesis of the Complex Non‐Ribosomal Peptide Polytheonamide B
Authors: Inoue Masayuki , Matsuoka Shigeru
Published: March 2011

Polytheonamide B, isolated from the Japanese marine spongeTheonella swinhoei, is by far the largest non‐ribosomal peptide known to date, and displays potent cytotoxicity. Its 48 amino acid residues include a variety of non‐proteinogenicD‐ andL‐amino acids, and the chiralities of these amino acids alternate in sequence. These structural features induce the formation of a stable β6.3‐helical structure in the hydrophobic environment, giving rise to an overall tubular structure of 45 Å in length. In a biological setting, this fold is believed to transport cations across the lipid bilayer through a pore with an inner diameter of 4 Å, thereby acting as an ion channel. In this account, we describe in detail our total synthetic route to polytheonamide B. The total synthesis relies on a combination of four key stages: synthesis of eight non‐proteinogenic amino acids and an N‐terminus moiety, a solid phase assembly of four fragments of polytheonamide B, three Ag+‐mediated couplings of the fragments, and finally, acid‐promoted global deprotection. The generality and modularity of the developed strategy will enable future studies of the chemical and biological properties of this unusual ion‐channel‐forming peptide and its synthetic analogues.
Maitotoxin: An Inspiration for Synthesis
Authors: Nicolaou K. C. , Aversa Robert J.
Published: March 2011

Maitotoxin holds a special place in the annals of natural products chemistry as the largest and most toxic secondary metabolite known to date. Its fascinating, ladder‐like, polyether molecular structure and diverse spectrum of biological activities elicited keen interest from chemists and biologists, who recognized its uniqueness and potential as a probe and inspiration for research in chemistry and biology. Synthetic studies in the area benefited from methodologies and strategies that were developed as part of chemical synthesis programs directed toward the total synthesis of some of the less complex members of the polyether marine biotoxin class, of which maitotoxin is the flagship. This account focuses on progress made in the authors’ laboratories in the synthesis of large maitotoxin domains with emphasis on methodology development, strategy design, and structural comparisons of the synthesized molecules with the corresponding regions of the natural product. The article concludes with an overview of maitotoxin’s biological profile and future perspectives.
A Decade of Oxothiomolybdenum Wheels: Synthesis, Behavior in Solution, and Electrocatalytic Properties
Authors: Lemonnier Jean‐François , Duval Sylvain , Floquet Sébastien , Cadot Emmanuel
Published: March 2011

The last decade has see the development of sulfur‐containing polyoxometalates (POTMs) as a subclass of the polyoxometalate family. The structural and physico‐chemical properties of this emerging class of compounds is dominating by the striking coordination properties of the [Mo2O2S2(OH2)6]2+ oxothio cation, used as a building block. The cyclic topology of this arrangement corresponds to the main feature of the {Mo2O2S2}‐based compounds, able to develop cycle‐based chemistry. The control of the linear oligomerization of the {Mo2O2S2} core is achieved by the presence of the anionic component, which acts as a template. Here, we report on recent examples which illustrate how the use of various template ions such as halide, sulfate, polyphosphate, and polycarboxylate anions allows to tune the nuclearity of the inorganic host from {Mo8} to {Mo18}. A special focus on behavior in solution is given, highlighting the dynamic and fluxional character of these host–guest systems. The Diffusion Ordered Spectroscopy (DOSY) 1H NMR, carried out on a large series of cycle‐based and capsule‐like compounds, demonstrates that such a method can be applied for the speciation of POM anions in solution. Finally, electrocatalytic behavior of the {Mo2O2S2}‐based compounds is presented. Preliminary results show that the electrocatalytic reduction of protons into hydrogen (HER) could constitute one of the most relevant applications for this class of molecular compounds.
Polyoxometalates in the Design of Effective and Tunable Water Oxidation Catalysts
Authors: Geletii Yurii V. , Yin Qiushi , Hou Yu , Huang Zhuangqun , Ma Huiyuan , Song Jie , Besson Claire , Luo Zhen , Cao Rui , O'Halloran Kevin P. , Zhu Guibo , Zhao Chongchao , Vickers James W. , Ding Yong , Mohebbi Sajjad , Kuznetsov Aleksey E. , Musaev Djamaladdin G. , Lian Tianquan , Hill Craig L.
Published: March 2011

Water oxidation catalysts (WOCs) are of core importance in several green energy production technologies, including water splitting and water reduction of CO2 driven by electrochemical potential and/or photons (radiant energy). General challenges in solar fuel generating structures, WOC design concepts, and some success‐limiting considerations in WOC development are described. The first class of WOCs are presented that combine the stability benefits of heterogeneous WOCs with the reactivity and other benefits of homogeneous WOCs.
Multimicroscopic study of curcumin effect on fixed nonmalignant and cancerous mammalian epithelial cells
Authors: Saab Marie‐belle , Estephan Elias , Bec Nicole , Larroque Marion , Aulombard Roger , Cloitre Thierry , Gergely Csilla
Published: March 2011

The morphology changes, in particular the organization of microtubules in mammalian nonmalignant HMEC 184A1 and cancerous MCF‐7 cells during curcumin treatment have been investigated by utilizing multiphoton, fluorescence, and atomic force (AFM) microscopies. Fluorescence microscopy reveals formation of ring‐like structures of microtubules circumscribing the nuclear area in HMEC 184A1 cells after treatment, while in MCF‐7 cells, no important changes were observed. Topography analyses of fixed HMEC 184A1 and MCF‐7 before and after treatment with curcumin were performed using AFM and the effect of the employed cells' fixation method was investigated on MCF‐7 cells. Due to its indepth optical sectioning capacity multiphoton microscopy provided valuable complementary information on curcumin's effect on both cells' types. Combining information provided by AFM and optical fluorescence and biphoton microscopes allows us to gain a better understanding of the cells and their curcumin‐induced changes, especially for microtubules which are the main target of antitumor chemotherapy treatments. Our multimicroscopic study demonstrates that 6 h incubation with curcumin does not induce significant modifications in the interphase microtubules in the malignant MCF7cell, whereas it has measurable effects on those of the nonmalignant HMEC 184A1 cells, revealing also morphology modifications over the nuclear area of these cells. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Biological behavior of pre‐osteoblasts on natural hydroxyapatite: A study of signaling molecules from attachment to differentiation
Authors: Zambuzzi Willian F. , Ferreira Carmen V. , Granjeiro José M. , Aoyama Hiroshi
Published: March 2011

Several biomaterials have been widely used in bone regeneration in both orthopedic and oral surgeries. However, it is poorly understood how these biomaterials alter osteoblast phenotype. It prompted us to examine the involvement of signaling proteins during preosteoblast adhesion (attachment), proliferation, and differentiation on natural hydroxyapatite (HA) from bovine bone. Our results indicated that natural HA is able to promote osteoblast adhesion, proliferation, and differentiation. The osteoblast/HA interaction requires phosphorylation of tyrosine residues of focal adhesion kinase, Src, and Paxillin upon integrin activation, which culminates in the control of cofilin phosphorylation (at serine 03) via rac‐1 activation. In part, these signaling pathways are responsible for actin‐rearrangement, responsible to adapt cell‐shape on HA particles. In regarding to osteoblast differentiation, we showed that natural HA favored extracellular matrix remodeling by stimulating matrix metalloproteinase activities and alkaline phosphatase activity. Overall, this study demonstrates that osteoblast response toward bovine bone HA is initially mediated by activation of focal adhesion components, culminating on actin‐rearrangement executed by cofilin activation via rac‐1. Moreover, bovine bone HA provided an excellent microenvironment for osteoblast activity, since adhesion to differentiation. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.
Microsphere‐integrated drug‐eluting stents: PLGA microsphere integration in hydrogel coating for local and prolonged delivery of hydrophilic antirestenosis agents
Authors: Indolfi Laura , Causa Filippo , Giovino Concetta , Ungaro Francesca , Quaglia Fabiana , Netti Paolo Antonio
Published: March 2011

The development of a novel generation of drug‐eluting stent (DES) relies upon the idea to obtain very flexible platforms able to overcome some issues associated to available devices and widen their field of application, especially to the currently emerging biotech therapeutics. Here, we propose a new concept of DES named microsphere‐integrated drug‐eluting stent (MIDES) composed of drug eluting biodegradable poly(D,L‐lactide‐co‐glycolide) microspheres—encapsulating an hydrophilic model molecule (dextran)—fully integrated in a poly(2‐hydroxy‐ethyl‐methacrylate) coating. By implementing a modified spray‐coating technique, we have been able to achieve a thin (10 μm), smooth, and homogeneous hydrogel surface embedding underneath a population of two different microparticles formulations—Dex502H and Dex506. The amount of drug can be tailored, resulting in a dextran loading as high as 1.4 μg/cm, by simply reiteration of coating layer deposition making the MIDES a custom‐made device where the release kinetics can be further modified by opportunely choosing microsphere properties. DES use is nowadays restricted to delivery of hydrophobic pharmaceuticals; release of hydrophilic therapeutics from MIDES can, however, be finely controlled by specifically engineering biodegradable microspheres. By varying polymer resomer, we obtained a tunable release rate in the first month of delivery. Depending on the microspheres properties release profile changes drastically moving from a biphasic release, in the case of Dex502H, with a burst of about 20% in the first day to a more sustained release for Dex506 particles. As proof of principle, we also demonstrated that MIDES approach can allows the delivery of two different agents opening up the way to a multitherapy in restenosis treatment. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.