bluuebunny/crossref_metadata_2025 huggingface dataset:
Seasonal and inter-annual variability of plankton chlorophyll and primary production in the Mediterranean Sea: a modelling approach
Authors: Lazzari P. , Solidoro C. , Ibello V. , Salon S. , Teruzzi A. , Béranger K. , Colella S. , Crise A.
Published: June 2011

Abstract. This study presents a model of chlorophyll and primary production in the pelagic Mediterranean Sea. A 3-D-ecosystem model (OPATM-BFM) was adopted to explore specific system characteristics and quantify key biogeochemical variables covering a 6-yr period, from 1999 to 2004. We show that, on a basin scale, the Mediterranean Sea is characterised by a high degree of spatial and temporal variability in terms of primary production and chlorophyll concentrations. On a spatial scale, important horizontal and vertical gradients have been observed. In particular, notable differences between surface net primary production variability and the corresponding vertically integrated production rates have been identified, suggesting that care must be taken when inferring productivity in such systems from satellite observations alone. The present study indicates that seasonal variability dominates inter-annual differences. According to the simulations over a 6-yr period, the developed model correctly simulated the climatological features of deep chlorophyll maxima and chlorophyll west-east gradients, as well as the seasonal variability in the primary offshore regions that were studied. The integrated net primary production highlights north-south gradients that differ from surface net primary production gradients and illustrates the importance of adopting a spatial and temporal description to calculate basin-wide budgets and their variabilities. According to the model, the western Mediterranean, in particular the Alboran Sea, can be considered mesotrophic, whereas the eastern Mediterranean is oligotrophic. Finally, specific simulations that were designed to explore the role of ecosystem boundary conditions were performed. The subsequent results show that the effects of atmospheric and terrestrial nutrient loads on the total integrated net primary production account for less than 5 % of the annual budget, whereas an increase of 30 % in the light extinction factor impacts primary production by approximately 10 %.
Impact of CO2 and climate on the Last Glacial Maximum vegetation: results from the ORCHIDEE/IPSL models
Authors: Woillez M.-N. , Kageyama M. , Krinner G. , de Noblet-Ducoudré N. , Viovy N. , Mancip M.
Published: June 2011

Abstract. Vegetation reconstructions from pollen data for the Last Glacial Maximum (LGM), 21 ky ago, reveal lanscapes radically different from the modern ones, with, in particular, a massive regression of forested areas in both hemispheres. Two main factors have to be taken into account to explain these changes in comparison to today's potential vegetation: a generally cooler and drier climate and a lower level of atmospheric CO2. In order to assess the relative impact of climate and atmospheric CO2 changes on the global vegetation, we simulate the potential modern vegetation and the glacial vegetation with the dynamical global vegetation model ORCHIDEE, driven by outputs from the IPSL_CM4_v1 atmosphere-ocean general circulation model, under modern or glacial CO2 levels for photosynthesis. ORCHIDEE correctly reproduces the broad features of the glacial vegetation. Our modelling results support the view that the physiological effect of glacial CO2 is a key factor to explain vegetation changes during glacial times. In our simulations, the low atmospheric CO2 is the only driver of the tropical forests regression, and explains half of the response of temperate and boreal forests to glacial conditions. Our study shows that the sensitivity to CO2 changes depends on the background climate over a region, and also depends on the vegetation type, needleleaf trees being much more sensitive than broadleaf trees in our model. This difference of sensitivity leads to a dominance of broadleaf types in the remaining simulated forests, which is not supported by pollen data, but nonetheless suggests a potential impact of CO2 on the glacial vegetation assemblages. It also modifies the competitivity between the trees and makes the amplitude of the response to CO2 dependent on the initial vegetation state.
Physical and numerical modelling of a bedload deposition area for an Alpine torrent
Authors: Kaitna R. , Chiari M. , Kerschbaumer M. , Kapeller H. , Zlatic-Jugovic J. , Hengl M. , Huebl J.
Published: June 2011

Abstract. Floods including intensive bedload transport represent a severe hazard to the often densely populated alluvial fans of small Alpine watersheds. In order to minimize the risk of future inundation, an existing bedload deposition area on the fan upstream of the village Vorderberg in southern Austria is planned for reconstruction. The suggested concept for protection measures includes dividing the area into three similar sections of reduced slope. The three sections are to be separated by a block ramp. To test this concept and to optimize the sedimentation process, an analysis was performed by using both a physical scale model (1:30) and a numerical simulation tool (SETRAC). Four configurations for the section-outlet were tested based on three flood scenarios. The results support the general protection concept and suggest a minimum construction configuration, including a woody debris filter. Employing a physical scale model for analysing small watershed processes is rarely found in literature. This contribution represents an applied study and provides quantitative information on bedload deposition and outflow from a deposition area. We test a novel simulation tool for bedload transport on the steep slopes against the measurements in the laboratory and show that the combination of physical and numerical modelling is a valuable tool to evaluate the efficiency of planned measures for torrent hazard mitigation.
HSP Induction in Mesothelial Cells by Peritoneal Dialysis Fluid Depends on Biocompatibility Test System
Authors: Bender Thorsten O. , Kratochwill Klaus , Böhm Michael , Jörres Achim , Aufricht Christoph
Published: May 2011

Background

We have previously shown that exposure of mesothelial cells (MC) to peritoneal dialysis fluids (PDF) not only caused toxic injury, but also induced cytoprotective heat shock proteins (HSP). This study was performed in order to compare HSP expression in MC upon PDF exposure in three currently used biocompatibility test systems.

Methods

Omentum-derived human peritoneal MC underwent 3 modalities of exposure to heat- or filter-sterilized PDF: (A) pure PDF for 60 minutes followed by a recovery-period in pure culture medium for 24 hours; (B) 1:1 mixture of PDF and culture medium for 24 hours or (C) pure PDF for 60 minutes followed by a recovery-period in a 1:1 mixture of PDF and culture medium for 24 hours. Biocompatibility was assessed by LDH-release into the supernatant and HSP-72 expression in MC lysates.

Results

Short-term exposure of MC to pure PDF (Modality A) resulted in concordant LDH release and upregulation of HSP-72, regardless of heat or filter sterilization. In contrast, both test systems that exposed MC to heat-sterilized PDF during the recovery period (Modalities B and C) resulted in severe cellular lethality but low HSP-72 expression.

Conclusions

This study clearly shows that HSP expression in MC upon PDF exposure depends on the biocompatibility test system. The presence of heat-sterilized PDF during recovery resulted in significant downregulation of HSP-72 despite severe cell injury. Therefore, HSP-72 expression reflects adequate cellular stress responses rather than PDF cytotoxicity.
Study exploring breast cancer screening practices amongst Arabic women living in the State of Qatar
Authors: Donnelly Tam Truong , Al-Khater Al-Hareth , Al-Kuwari Mohamed , Al-Meer Nabila , Al-Bader Salha Bujassoum , Malik Mariam , Singh Rajvir , Jong Floor Christie-de
Published: May 2011

Breast cancer is a public health threat in the State of Qatar. It is the most common cancer and the incidence rate is increasing. It has been found that women often present with breast cancer at advanced stages in Qatar. Early detection of breast cancer is an important prognostic factor and breast cancer screening has been found successful in decreasing mortality rates. The percentage of women in Qatar engaging in screening activities is alarmingly low. A study has been designed to examine barriers and facilitators that are potentially influencing women in participating in breast cancer screening activities. Understanding these barriers and facilitators is essential in order to create a culturally appropriate and effective intervention that can encourage women in Qatar to participate in screening activities. In this paper the background to the study is presented which highlights the magnitude of the breast cancer problem in Qatar and offers the rationale and information for this potentially groundbreaking study.
Fuzzy Logic Partition-Based Call Admission Control for Mobile WiMAX
Authors: Shu'aibu D. S. , Syed Yusof S. K. , Fisal N. , Ariffin S. H. S. , Rashid R. A. , Abdul Latiff N. M. , Baguda Y. S.
Published: June 2011

The unpredictable nature of the wireless network and exponential growth in traffics with different quality of service requirements has led hardware complexity to escalate. In order to effectively control and manage the network traffics, there is a need for intelligent call admission control (CAC) in admitting traffics into the wireless network that provides necessary quality of service. In this paper, we propose a fuzzy logic partition-based call admission control (FZ CAC). The scheme primarily partitions the total link bandwidth into three which corresponds to constant bit rate (CBR), variable bit rate (VBR) and handover (HO) services. The fuzzy logic admission control scheme was implemented in the HO portion to intelligently keep dropping probability as low as possible based on the available bandwidth. Simulation results showed that the proposed approach outperformed both partition-based CAC (PB CAC) and conventional bandwidth allocation CAC (CB CAC).
Identifying Enablers of E-Manufacturing
Authors: Saha Rajeev , Grover Sandeep
Published: May 2011

The term e-manufacturing refers to the ability of a manufacturing system to integrate various inputs using internet and intranet. With the market being increasingly competitive and customer oriented desiring to get best of the quality at cheapest available price of a product in shortest possible time, the role of e-manufacturing is pivotal towards the success of a company. Another important fact is that each customer may desire to have a certain different set of values added to the product being purchased. Customers want to voice their concerns directly to manufacturers thereby necessitating an interface to hear them in real-time and take suitable action thereupon, if needed, in real-time. As such identifying the enablers of e-manufacturing has become important for manufacturer in customer-oriented manufacturing to lure new customers along with retaining the old customers. It will also result in closing the gap between demand and supply of a product. This paper tries to assimilate the key enablers of e-manufacturing.
Synchronization of Time Delayed Systems by Common Delay Time Modulations
Authors: Mukherjee Atanu , Ghosh Dibakar , Banerjee Santo
Published: May 2011

We investigate the synchronization phenomenon between two identical time delayed systems with the common time delay, modulated by a chaotic or random signal. The phenomenon is verified by the conditional Lyapunov exponent. The relation between the present form of synchronization with generalized one is also discussed.
Intrapericardial Giant Lipoma Displacing the Heart
Authors: Steger C. M.
Published: May 2011

Despite their benign character, intrapericardial lipomas can cause life-threatening complications by rapid growth. This paper presents a case of an intrapericardial lipoma in an almost asymptomatic 41-year-old female patient only suffering from mild dyspnoea on exertion. The tumour was found incidentally by chest X-ray. Echocardiographic examination and a CT scan of the thorax revealed a 16 × 14 × 12 cm lipomatous tumour mass highly suspective of a lipoma. Histological examination of excised tumour specimens confirmed the diagnosis of a lipoma. The patient is currently asymptomatic and has not presented with evidence of recurrence at the 6-month followup.
Investigation of the Adhesion Promoter Distribution in Porous Ceramic Precursors
Authors: Steier Volker , Koplin Christof , Kailer Andreas , Reinecke Holger
Published: June 2011

The purpose of this paper is to improve the mechanical properties of polymer infiltrated ceramics (PICs) by the enhancement of the adhesion between both components. To improve the interface adhesion, an adhesion promoter (silane) was used. The silane distribution in the precursors was studied using Raman and IR spectroscopy. Inhomogeneous silane distribution was found after applying a common surface modification method. In this paper, different silane modification methods were developed. The methods differ in the manner of the infiltration solution, the point of silane activation, and the infiltration pressure. The impacts achieved by the use of these methods were analyzed, and different adhesion mechanisms between silane molecules and the ceramic surface were established. As a result, a unique infiltration method which generates homogeneous silane distributions was developed. The interface adhesion depends among other parameters on the silane amount on the surface. The adjustment of the silane amount in the precursor was realized by the use of IR-spectroscopy.
Mechanisms of Brain Aging Regulation by Insulin: Implications for Neurodegeneration in Late-Onset Alzheimer's Disease
Authors: Schuh Artur F. , Rieder Carlos M. , Rizzi Liara , Chaves Márcia , Roriz-Cruz Matheus
Published: May 2011

Insulin and IGF seem to be important players in modulating brain aging. Neurons share more similarities with islet cells than any other human cell type. Insulin and insulin receptors are diffusely found in the brain, especially so in the hippocampus. Caloric restriction decreases insulin resistance, and it is the only proven mechanism to expand lifespan. Conversely, insulin resistance increases with age, obesity, and sedentarism, all of which have been shown to be risk factors for late-onset Alzheimer's disease (AD). Hyperphagia and obesity potentiate the production of oxidative reactive species (ROS), and chronic hyperglycemia accelerates the formation of advanced glucose end products (AGEs) in (pre)diabetes—both mechanisms favoring a neurodegenerative milieu. Prolonged high cerebral insulin concentrations cause microvascular endothelium proliferation, chronic hypoperfusion, and energy deficit, triggeringβ-amyloid oligomerization and tau hyperphosphorylation. Insulin-degrading enzyme (IDE) seems to be the main mechanism in clearingβ-amyloid from the brain. Hyperinsulinemic states may deviate IDE utilization towards insulin processing, decreasingβ-amyloid degradation.
A Simplified Procedure for Base Sliding Evaluation of Concrete Gravity Dams under Seismic Action
Authors: Basili M. , Nuti C.
Published: May 2011

Possible base sliding induced by an earthquake on concrete gravity
dams is obtained by a simplified procedure. The model is a nonlinear single-degree-of-freedom system which takes into account dam-water-foundation interaction based on the model developed by Fenves and Chopra (1987). The nonlinearity is in the foundation rock, since a threshold value for the sliding foundation resistance, modeled with the Mohr-Coulomb yielding criterion including a frictional and a cohesive component, is imposed. Nonlinear step by
dams is obtained by a simplified procedure. The model is a nonlinear single-degree-of-freedom system which takes into account dam-water-foundation interaction based on the model developed by Fenves and Chopra (1987). The nonlinearity is in the foundation rock, since a threshold value for the sliding foundation resistance, modeled with the Mohr-Coulomb yielding criterion including a frictional and a cohesive component, is imposed. Nonlinear step by
step dynamic analyses are carried out on four case studies representing typical
examples of Italian concrete gravity dams by utilizing several natural earthquakes. On the basis of the obtained results, a simplified methodology to
estimate residual displacement without performing nonlinear dynamic analysis is presented. An example of application using as seismic input the elastic
response spectra furnished by the Italian Code is also presented.
Chloroformic and Methanolic Extracts of Olea europaea L. Leaves Present Anti-Inflammatory and Analgesic Activities
Authors: Chebbi Mahjoub R , Khemiss M. , Dhidah M. , Dellaï A. , Bouraoui A. , Khemiss F.
Published: May 2011

Olea europaea L. is used in traditional medicine in the Mediterranean areas. Its natural products are used in the treatment of different disorders, like fighting fever and some infectious diseases such as malaria, the treatment of arrhythmia, and relief of intestinal spasms.
The aim of the current study is to investigate the possible anti-inflammatory and anatinociceptive effects of methanol and chloroformic extracts prepared from leaves of Olea europaea L. The anti-inflammatory and antinociceptive effects of the different extracts of Olea europaea leaves were assessed after intraperitoneal administration into rats and mice, using the carrageenan-induced paw edema model in rats to test the anti-inflammatory effect and the acetic acid-induced writhing in mice to test the analgesic effect. The chloroformic and methanolic leaves extracts, studied at the doses of 50, 100, and 200 mg/kg (Body Weight: BW), exhibited significant dose-dependent anti-inflammatory and analgesic activities.
Based on the results obtained, it can be concluded that Olea europaea leaves extracts
have anti-inflammatory and antinociceptive effects.
Comparison of 12-Month Outcomes with Zotarolimus- and Paclitaxel-Eluting Stents: A Meta-Analysis
Authors: Loomba Rohit S. , Chandrasekar Suraj , Malhotra Neil , Arora Rohit R.
Published: May 2011

Revascularization after myocardial infarction is often achieved via percutaneous coronary intervention, which often entails stenting. Drug-eluting stents have shown benefits over bare metal stents in this setting, and a variety of drug-eluting stents are now available, including sirolimus-, paclitaxel-, and zotarolimus-eluting stents. There are studies that have compared the various drug-eluting stents and this meta-analysis pools data comparing 12-month clinical outcomes of zotarolimus- and paclitaxel-eluting stents. End points studied were myocardial infarction, major adverse cardiac events, cardiac death, all-cause death, stent thrombosis, target vessel revascularization, and target lesion revascularization.There was a statistically significant reduction in risk of myocardial infarction (odds ratio, 0.250, confidence interval, 0.160 to 0.392) and statistically insignificant reductions in major adverse cardiac events (odds ratio, 0.813, confidence interval, 0.656 to 1.007), cardiac death (odds ratio, 0.817, confidence interval, 0.359 to 1.857), all cause death (odds ratio, 0.820, confidence interval, 0.443 to 1.516), and target lesion revascularization (odds ratio, 0.936, confidence interval 0.702 to 1.247). There was a statistically significant increase in target vessel revascularization (odds ratio, 1.336, confidence interval, 1.003 to 1.778) and a statistically insignificant increase in stent thrombosis (odds ratio, 1.174, confidence interval, 0.604 to 2.280). These findings are similar to the individual studies although other studies have noted increased late loss with zotarolimus-eluting stents and this current data associated with late loss should be kept in mind when makimg clinical decisions regarding sent selection.
Psychosocial Health Status of Persons Seeking Treatment for Exposure to Libby Amphibole Asbestos
Authors: Weinert Clarann , Hill Wade G. , Winters Charlene A. , Kuntz Sandra W. , Rowse Kimberly , Hernandez Tanis , Black Brad , Cudney Shirley
Published: May 2011

A cross-sectional exploratory study was conducted to describe the psychosocial health status of persons seeking health care for exposure to Libby amphibole asbestos (LAA). Health indicators including depression, stress, acceptance of illness, and satisfaction with access and financial aspects of care were obtained via electronic and paper-pencil survey. The exposure pathway and demographic data were gleaned from the health record. Of the 386 participants, more than one-third (34.5%) demonstrated significant levels of psychological distress. The oldest group of women had the lowest levels of depression and stress and the highest acceptance of illness. Gender, age, and satisfaction with financial resources were significantly related to depression, stress, and acceptance of illness. Satisfaction with access to care was significant only for stress. No differences in depression, stress, and acceptance of illness were found based on residence, exposure pathway, or insurance status.
Needle Gauge and Cytological Yield in CT-Guided Lung Biopsy
Authors: Moore William , Sawas Ayman , Lee Cindy , Ferretti John
Published: June 2011

Rationale and Objectives. The aim of this study is to determine the effect of needle size on the diagnostic yield and complication rate of lung nodule biopsy.
Materials and Methods. A total of 209 patients are included in a retrospective study. All patients underwent a needle lung biopsy under computer-tomography-guided guidance. Multiple different needle gauges are used in this study.
Results. We found no correlation between the gauge of the needle and the incidence of complications or diagnostic yield associated with lung nodule biopsy. However, there was a statistically significant difference in the number of needle passes and the gauge of the needle ().
Conclusion. Using a larger gauge needle does not correlate with an increase in complication rate. However, there is a statically significant decrease in the number of needle passes using a larger gauge needle. While the diagnostic yield comparing small gauge needle and large gauge needle was not statistically different, this lack of difference in yield could be related to the difference in number of passes. The use of larger needle is likely to decrease number of passes, thereby resulting in decreased procedure times.
Study on Noise Prediction and Reduction in Coupled Workshops Using SEA Method
Authors: Lei Ye , Pan Jie , Sheng Meiping
Published: June 2011

A theoretical model for predicting noise reduction in coupled workshops is presented by using statistical energy analysis (SEA) method. An opening between the coupled workshops is considered into the theoretical model properly. The leakage issue is dealt with in the process of SEA modeling. An experiment is also carried out. A reasonable agreement between the prediction of noise reduction and the experimental data is observed. Moreover, it is concluded from the simulations that the sound energy transmit through the opening was the most important way to affect the noise reduction and the leakage is a significant element to influence the effect of noise treatment.
Thrombin activatable fibrinolysis inhibitor
Authors: Declerck P. J.
Published: June 2011

Thrombin activatable fibrinolysis inhibitor (TAFI) was discovered two decades ago as a consequence of the identification of an unstable carboxypeptidase (CPU), which was formed upon thrombin activation of the respective pro-enzyme (proCPU). The antifibrinolytic function of the activated form (TAFIa, CPU) is directly linked to its capacity to remove C-terminal lysines from the surface of the fibrin clot. No endogenous inhibitors have been identified, but TAFIa activity is regulated by its intrinsic temperature-dependent instability with a half-life of 8 to 15 min at 37 °C. A variety of studies have demonstrated a role for TAFI/TAFIa in venous and arterial diseases. In addition, a role in inflammation and cell migration has been shown. Since an elevated level of TAFIa it is a potential risk factor for thrombotic disorders, many inhibitors, both at the level of activation or at the level of activity, have been developed and were proven to exhibit a profibrinolytic effect in animal models. Pharmacologically active inhibitors of the TAFI/TAFIa system may open new ways for the prevention of thrombotic diseases or for the establishment of adjunctive treatments during thrombolytic therapy.
Induced Chain Alignment of Conjugated Polymers Within Nanoporous Template
Authors: Lo Kuan‐Hsin , Ho Rong‐Ming , Liao Yung‐Ming , Hsu Chain‐Shu , Massuyeau Florian , Zhao Yuan‐Chun , Lefrant Serge , Duvail Jean‐Luc
Published: May 2011

This work presents a simple method to generate ordered conjugated polymer nanoarrays through a pore‐filling process for nanoporous polymer templates so as to enhance the efficiency of photoluminescence (PL). PL results combined with the morphological evolution examined by scanning probe microscopy revealed that the enhanced PL reaches maximum intensity as the template pores are completely filled by conjugated polymers. Polarized PL spectroscopy and grazing incidence Fourier transform infrared spectroscopy were used to determine the chain orientation of templated conjugated polymer; the spectroscopic results indicate a parallel chain orientation along the cylindrical direction of nanopores. The induced alignment of the polymer chains is attributed to a nanoscale spatial effect that increases the PL intensity and the lifetime of the conjugated polymer. The enhanced luminescence of nanostructured conjugated polymers is highly promising for use in designing luminescent nanodevices.
Ionic Space‐Charge Depletion in Lithium Fluoride Thin Films on Sapphire (0001) Substrates
Authors: Li Chilin , Guo Xiangxin , Gu Lin , Samuelis Dominik , Maier Joachim
Published: May 2011

Lithium fluoride thin films with various thicknesses have been grown on c‐plane sapphire substrates by radio‐frequency sputtering. The thin films are granular with a preferential [111] orientation of the grains. Thickness‐dependent measurements allow the separation of bulk and interface conductions. The normalized conductance decreases linearly with decreasing LiF layer thickness with a negative extrapolated intercept. DC polarization, AC impedance spectroscopy and electromotive force measurement indicate depletion of lithium ion vacancies as majority charge carriers and hence a negative space‐charge potential. A generalized Mott–Schottky approach within the model of heterogeneous doping fully explains the entire boundary defect chemistry.
Electroactive Self‐Assembled Monolayers for Enhanced Efficiency and Stability of Electropolymerized Luminescent Films and Devices
Authors: Lv Ying , Yao Liang , Gu Cheng , Xu Yuanxiang , Liu Dandan , Lu Dan , Ma Yuguang
Published: May 2011

In order to further improve the efficiency and stability of luminescent electrochemical polymerization (EP) films and devices, electroactive self‐assembled monolayers (SAMs) of carbazolyl alkanethiol are successfully designed and applied to modify Au electrode and covalently graft the deposited EP films. The analysis of the formation and coverage of the SAMs by atomic force microscopy (AFM), cyclic voltammetry (CV), and the theoretical calculation provide consistent results indicating the SAM molecules are densely packed and standing upright (liquid‐like) on the Au surface. In addition, ultraviolet photoelectron spectroscopy (UPS), CV, UV, AFM, and sonication treatment reveal that the close‐packed electroactive SAMs are effective at enhancing the work function of electrode, increasing the deposition rate of EP precursor as well as elevating the cross‐linking efficiency and the adhesive property of subsequent EP films. This is a simple and very efficient method for improving the performance of EP device, which has potential applications in display devices.
Liquid‐Crystalline Ordering Helps Block Copolymer Self‐Assembly
Authors: Yu Haifeng , Kobayashi Takaomi , Yang Huai
Published: May 2011

Interaction between liquid‐crystalline elastic deformation and microphase separation in liquid‐crystalline block copolymers enables them to supramolecularly assemble into ordered nanostructures with high regularity. With the help of liquid‐crystalline alignment, parallel and perpendicular patterning of nanostructures is fabricated with excellent reproducibility and mass production, which provides nanotemplates and nanofabrication processes for preparing varieties of nanomaterials. Furthermore, nanoscale microphase separation improves the optical performance of block‐copolymer films by eliminating the scattering of visible light, leading to advanced applications in optical devices and actuators. Recent progress in liquid‐crystalline block copolymers, including their phase diagram, structure‐property relationship, nanostructure control and nanotemplate applications, is reviewed.
Weyl geometric gravity and electroweak symmetry “breaking”
Authors: Scholz E.
Published: May 2011

A Weyl geometric scale covariant approach to gravity due to Omote, Dirac, and Utiyama (1971ff) is reconsidered. It can be extended to the electroweak sector of elementary particle fields, taking into account their basic scaling freedom. Already Cheng (1988) indicated that electroweak symmetry breaking, usually attributed to the Higgs field with a boson expected at 0.1–0.3 TeV, may be due to a coupling between Weyl geometric gravity and electroweak interactions. Weyl geometry seems to be well suited for treating questions of elementary particle physics, which relate to scale invariance and its “breaking”. This setting suggests the existence of a scalar field boson at the surprisingly low energy of ∼ 1 eV. That may appear unlikely; but, as a payoff, the acquirement of mass arises as a result of coupling to gravity in agreement with the understanding of mass as the gravitational charge of fields.
Nanopartikel für die Aufwärtskonversion
Authors: Haase Markus , Schäfer Helmut
Published: May 2011

Mit Upconversion (UC, Aufwärtskonversion) werden nichtlineare optische Prozesse beschrieben, bei denen die aufeinander folgende Absorption von zwei oder mehr Photonen mit vergleichsweise großer Wellenlänge zur Emission von Strahlung mit kürzerer Wellenlänge (Emission vom anti‐Stokes‐Typ) führt. Im Unterschied zu anderen Emissionen auf Basis einer Mehrphotonenabsorption können UC‐Prozesse auch mit niedrigen Energiedichten effizient angeregt werden. Die effizientesten heute bekannten UC‐Prozesse werden in Seltenerd‐dotierten Festkörperverbindungen beobachtet. Die Forschungen auf dem Gebiet nanokristalliner Materialien führten schließlich zur Entwicklung von Synthesemethoden für kleine, hocheffiziente UC‐Partikel mit enger Partikelgrößenverteilung, die transparente Lösungen in einer Vielzahl von Lösungsmitteln bilden. Mittlerweile gibt es Syntheserouten für qualitativ hochwertige UC‐Nanokristalle, die eine Steuerung von kolloidaler Löslichkeit, Partikelgröße, Kristallstruktur, optischen Eigenschaften und Partikelform ermöglichen. Zurzeit werden diese Partikel als vielversprechende Alternative zu organischen Fluorophoren und Halbleiternanopartikeln (“Quantenpunkten”) in der medizinischen Bildgebung diskutiert.
Upconverting Nanoparticles
Authors: Haase Markus , Schäfer Helmut
Published: May 2011

Upconversion (UC) refers to nonlinear optical processes in which the sequential absorption of two or more photons leads to the emission of light at shorter wavelength than the excitation wavelength (anti‐Stokes type emission). In contrast to other emission processes based on multiphoton absorption, upconversion can be efficiently excited even at low excitation densities. The most efficient UC mechanisms are present in solid‐state materials doped with rare‐earth ions. The development of nanocrystal research has evoked increasing interest in the development of synthesis routes which allow the synthesis of highly efficient, small UC particles with narrow size distribution able to form transparent solutions in a wide range of solvents. Meanwhile, high‐quality UC nanocrystals can be routinely synthesized and their solubility, particle size, crystallographic phase, optical properties and shape can be controlled. In recent years, these particles have been discussed as promising alternatives to organic fluorophosphors and quantum dots in the field of medical imaging.
Olefin isomerization reactions catalyzed by ruthenium hydrides bearing Schiff base ligands
Authors: Ding Fu , Doorslaer Sabine Van , Cool Peggie , Verpoort Francis
Published: May 2011

A series of in situ‐generated ruthenium hydride complexes Ru(PPh3)2(CO)H(Ln) (n = a–h) incorporating a Schiff base ligand was investigated for the isomerization of olefins. 1H‐NMR was used to characterize the new hydride species in combination with 31P‐NMR. Allylbenzene and 1‐octene were used as model substrates. Temperature, solvents and catalyst/substrate mole ratio were taken into account as parameters to optimize the isomerization reaction. All catalysts showed the best performance in 2‐butanol, suggesting that the catalytic activity depends not only strongly on the steric and electronic environment of the ruthenium but also on the chosen solvent. Copyright © 2011 John Wiley & Sons, Ltd.
A discrete time model for software reliability with application to a flight control software
Authors: Dewanji Anup , Sengupta Debasis , Chakraborty Ashis Kumar
Published: May 2011

This work is motivated by a particular software reliability problem in a unit of flight control software developed by the Indian Space Research Organization (ISRO), in which the testing of the software is carried out in multiple batches, each consisting of several runs. As the errors are found during the runs within a batch, they are noted, but not debugged immediately; they are debugged only at the end of that particular batch of runs. In this work, we introduce a discrete time model suitable for this type of periodic debugging schedule and describe maximum likelihood estimation for the model parameters. This model is used to estimate the reliability of the software. We also develop a method to determine the additional number of error‐free test runs required for the estimated reliability to achieve a specific target with some high probability. We analyze the test data on the flight control software of ISRO. Copyright © 2011 John Wiley & Sons, Ltd.
Multiplexing and demultiplexing logic functions for computing signal processing tasks in synthetic biology
Authors: Pasotti Lorenzo , Quattrocelli Mattia , Galli Daniela , De Angelis Maria Gabriella Cusella , Magni Paolo
Published: May 2011

Building biological devices to perform computational and signal processing tasks is one of the main research issues in synthetic biology. Herein, two modular biological systems that could mimic multiplexing and demultiplexing logic functions are proposed and discussed. These devices, called multiplexer (mux) and demultiplexer (demux), respectively, have a remarkable importance in electronic, telecommunication, and signal processing systems and, similarly, they could play a crucial role if implemented in a living organism, such as Escherichia coli. BioBrick standard parts were used to design mux and demux and to construct two genetic circuits that could carry out the desired tasks. A modular approach, mimicking basic logic gates (AND, OR, and NOT) with protein/autoinducer or protein/DNA interactions and interconnecting them to create the final circuits, was adopted. A mathematical model of the designed gene networks was been defined and simulations performed to validate the expected behavior of the systems. In addition, circuit subparts were tested in vivo and the results used to determine some of the parameters of the mathematical model. According to both the experimental and simulated results, guidelines for future finalization of mux and demux are provided.
Directed Evolution of an Error‐Prone T7 DNA Polymerase that Attenuates Viral Replication
Authors: Söte Sandra , Kleine Stefan , Schlicke Marina , Brakmann Susanne
Published: May 2011

Experimental evidence exists that RNA viruses replicate with extremely high mutation rates that result in significant genetic diversity. The diverse nature of viral populations allows rapid adaptation to dynamic environments, and evolution of resistances to vaccines as well as antiviral substances. For DNA viruses that replicate at much greater fidelities, as yet, neither diverse structures in the population nor their responses to increased mutation rates have been sufficiently described. By using the example of DNA bacteriophage T7, we describe the identification of virus‐specific DNA polymerase variants with decreased replication fidelities, and their impact on the efficiency of the viral infection cycle.
A Fast and Precise Approach for Computational Saturation Mutagenesis and its Experimental Validation by Using an Artificial (βα)8‐Barrel Protein
Authors: Fischer Andre , Seitz Tobias , Lochner Adriane , Sterner Reinhard , Merkl Rainer , Bocola Marco
Published: May 2011

We present a computational saturation mutagenesis protocol (CoSM) that predicts the impact on stability of all possible amino acid substitutions for a given site at an internal protein interface. CoSM is an efficient algorithm that uses a combination of rotamer libraries, side‐chain flips, energy minimization, and molecular dynamics equilibration. Because CoSM considers full side‐chain and backbone flexibility in the local environment of the mutated position, amino acids larger than the wild‐type residue are also modeled in a proper manner. To assess the performance of CoSM, the effect of point mutations on the stability of an artificial (βα)8‐barrel protein that has been designed from identical (βα)4‐half barrels, was studied. In this protein, position 234N is a previously identified stability hot‐spot that is located at the interface of the two half barrels. By using CoSM, changes in protein stability were predicted for all possible single point mutations replacing wild‐type Val234N. In parallel, the stabilities of 14 representative mutants covering all amino acid classes were experimentally determined. A linear correlation of computationally and experimentally determined energy values yielded an R2 value of 0.90, which is statistically significant. This degree of coherence is stronger than the ones we obtained for established computational methods of mutational analysis.
Development of a Whole Cell Biocatalyst for the Efficient Prenylation of Indole Derivatives by Autodisplay of the Aromatic Prenyltransferase FgaPT2
Authors: Kranen Eva , Steffan Nicola , Maas Ruth , Li Shu‐Ming , Jose Joachim
Published: May 2011

The following study depicts the development of a whole cell biocatalyst for the prenylation of indole derivatives. For this purpose the prenyltransferase FgaPT2 from Aspergillus fumigatus was displayed on the surface of Escherichia coli cells by using Autodisplay. The presence of the prenyltransferase in the outer membrane was detected by using SDS‐PAGE and Western Blot after the proteins of the outer membrane were isolated. The orientation of the prenyltransferase towards the outside of the cells was investigated by accessibility testing with externally added proteases. The FgaPT2 whole cell biocatalyst converted up to 250 μM of indole‐3‐propionic acid, approximately 25 % of the substrate used in the assay (100 μL sample, OD578=40). Another indole substrate, L‐β‐homotryptophan was also investigated and a conversion of 13 % was determined. By optimizing the assay conditions the conversion rate could be raised to approximately 30 % of indole‐3‐propionic acid during a 24 h incubation time at 20 °C. The whole cell biocatalyst endured a storage period of one month at 8 °C without any detectable loss in activity. Reusability was confirmed by recycling the biocatalyst. After three cycles of consecutive use, the whole cell biocatalyst retained a conversion rate of 46 % of indole‐3‐propionic acid and 23 % of L‐β‐homotryptophan after the third cycle.
Influence of Solvent Polarity on the Mechanism and Efficiency of Formic Acid Reactive Extraction with Tri‐n‐Octylamine from Aqueous Solutions
Authors: Galaction A.‐I. , Kloetzer L. , Cascaval D.
Published: May 2011

The reactive extractions of formic acid with tri‐n‐octylamine (TOA) dissolved in three solvents with different dielectric constants (dichloromethane, butyl acetate, n‐heptane) without and with 1‐octanol as phase modifier were comparatively analyzed. The results indicated that the mechanism of the interfacial reaction between acid and extractant (Q) is controlled by the organic phase polarity. In the absence of 1‐octanol, the structures of the extracted complexes are (HA)2Q2 for dichloromethane and butyl acetate, and (HA)2Q4 for n‐heptane. These structures are modified by adding 1‐octanol and become (HA)2Q for extraction in dichloromethane or butyl acetate, and (HA)2Q2 for extraction in n‐heptane. Although the presence of 1‐octanol improves the extraction efficiency, it leads to a reduction of the extraction constants for all considered solvents, an influence that is more significant for n‐heptane.
Modeling the Growth Kinetics of Fluidized‐Bed Spray Granulation
Authors: Li Z. , Kind M. , Gruenewald G.
Published: May 2011

Fluidized‐bed spray granulation is used to produce porous granular particles from suspensions, solutions, and melts. In this work, the adapted two‐fluid model approach is used to simulate the fluid dynamics in the fluidized bed, and a simplified direct quadrature method of moments is adopted to mimic the full particle size distribution. The size‐dependent growth kinetics is obtained by computational fluid dynamics simulation for short process times from the modeling of drop deposition on the particles. This kinetics is used in the population balance equation to predict the evolution of the full particle size distribution for long process times. Such a multiscale approach allows for a description of continuous granulation processes.
Particle Residence Times in Fluidized Bed Granulation Equipments
Authors: Börner M. , Peglow M. , Tsotsas E.
Published: May 2011

Various types of fluidized bed equipments used in granulation were experimentally investigated in order to gain a more detailed insight in particle recirculation behavior and particle residence times in the two considered compartments, namely the spray compartment and the drying compartment. The investigated fluidized bed technologies comprise a top‐spray process, a spout fluidized bed without and with internal riser, and a spouted bed. The measurements were conducted by using image analysis techniques on an almost 2D particle flow. From the results, conclusions about particle wetting and drying can be extracted, subject to fluidization velocity, nozzle mass flow rate, and facility/riser construction.
Influence of the Spray Method on Product Quality and Morphology in Spray Drying
Authors: Walzel P.
Published: May 2011

The spraying system is responsible for the particle formation and spray pattern. The most important features of sprays emerging from different atomizers are discussed. In the case of pneumatic atomizers the entrainment is low and a well‐mixed jet with little segregation of fine and large particles occurs. A much stronger interaction of gas and spray takes place in the case of large spray angles as, e.g., produced by rotary atomizers. To some extent the particle morphology is known to depend on the drying speed and thus on the entrainment.
Facile Fabrication of Hollow Mesoporous Silica Nanospheres for Superhydrophilic and Visible/Near‐IR Antireflection Coatings
Authors: Du Xin , He Junhui
Published: May 2011

A series of hierarchically mesostructured silica nanoparticles (MSNs) less than 100 nm in size were fabricated by means of a one‐step synthesis using dodecanethiol (C12SH) and cetyltrimethylammonium bromide (CTAB) as the dual template, and trimethylbenzene (TMB) as the swelling agent. Silica nanoparticles with varied morphologies and structures, including mesoporous silica nanoparticles with tunable pore size, mesoporous silica nanoparticles with a thin solid shell, hollow mesoporous silica nanoparticles with tunable cavity size, and hollow mesoporous silica nanoparticles with a thin solid shell, were obtained by regulating the TMB/CTAB molar ratio and the stirring rate with the assistance of C12SH. Silica particulate coatings were successfully fabricated by using MSNs with varied morphologies and structures as building block through layer‐by‐layer dip‐coating on glass substrates. The thickness and roughness of the silica particulate coatings could be tailored by regulating the deposition cycles of nanoparticles. The silica particulate coatings composed of hollow mesoporous silica nanoparticles with a thin shell (S2) increased the maximum transmittance of slide glass from 90 to 96 %, whereas they reduced its minimum reflection from 8 to 2 % at the optimized wavelength region that could be adjusted from visible to near‐IR with a growing number of deposition cycles. The coatings also exhibited excellent superhydrophilic and antifogging properties. These mesostructured silica nanoparticles are also expected to serve as ideal scaffolds for biological, medical, and catalytic applications.
Spectroelectrochemical Evidence for the Nitrosyl Redox Siblings NO+, NO., and NO− Coordinated to a Strongly Electron‐Accepting FeII Porphyrin: DFT Calculations Suggest the Presence of High‐Spin States after Reduction of the FeII–NO− Complex
Authors: Pellegrino Juan , Hübner Ralph , Doctorovich Fabio , Kaim Wolfgang
Published: May 2011

Experimental and computational results for the electron‐deficient porphyrin complex [Fe(NO)(TFPPBr8)] (1; TFPPBr8=2,3,7,8,12,13,17,18‐octabromo‐5,10,15,20‐tetrakis(pentafluorophenyl)porphyrin) are reported with respect to its electron‐transfer behavior. Complex 1 undergoes three one‐electron processes: two reversible reductions and one irreversible oxidation. Spectroelectrochemical measurements (IR and UV/Vis/NIR spectroscopy) of 14NO‐ and 15NO‐containing material indicate that the first reduction to 1− occurs largely on the NO ligand to produce nitroxyl anion (NO−) character, as evident from the considerable change in νNO from 1715 to around 1550 cm−1. The second reduction to 12− does not result in a further shift of νNO to lower frequencies, but to a surprising high‐energy shift to 1590 cm−1. This and the notable changes of the characteristic porphyrin vibrations as well as significant changes of the UV/Vis absorptions indicate a porphyrin‐centered process; DFT calculations predict the shift of νNO to higher frequencies for the intermediate‐ and high‐spin states of 12−. The oxidation of 1 is irreversible on the voltammetry timescale, but chemically reversible in spectroelectrochemical experiments, suggesting that the cationic form dissociates to the corresponding ferric porphyrin and NO. DFT calculations support the interpretation of the experimental results.