bluuebunny/crossref_metadata_2025 huggingface dataset:
Attenuation estimation in thin transitional layers with gradational velocity change
Authors: Tian Gang , Cheng Suo , Shi Zhanjie , Wang Kai
Published: August 2009

In a desert area, unconsolidated sediment can seriously attenuate the high frequency components of seismic data. In order to evaluate the attenuation of a seismic wave in the medium, we firstly analysed the primary seismic wave from up‐hole survey data acquired from the Takelamagan desert of north‐west China and then performed numerical simulations. The up‐hole results showed that there is a stratum in which the velocity increases gradually when the depth increases and where amplitudes and frequency components are attenuated and are decreased seriously by the waves being reflected or passing through the stratum. We regard the stratum as a linear transition layer. Based on the linear transition theory and the velocity structures obtained from up‐hole data, the one‐dimensional numerical simulation method was used to calculate seismograms of transmission waves and reflection waves. By analysing these two records, it was found that both amplitudes and frequency components attenuated greatly due to the existing linear transition layer. This can be interpreted as scattering or multiples since the reflection and the transmission actions usually occurred in this kind of stratum more than once. This is a significant factor for the amplitudes and frequency components attenuation of a partially saturated layer in a desert area. The filter character of the transition stratum can be described as a low‐pass filter for reflection waves and as a high‐pass filter for transmission waves.
The lining quality detection and grouting effect evaluation of the Kunlun Mountain railway tunnel using ground‐penetrating radar
Authors: Zhang Li , Liu Zhengping , Gong Chengming
Published: August 2009

The ground‐penetrating radar (GPR) method is increasingly applied to the quality evaluation of large‐scale civil engineering projects due to its accuracy, non‐destructive application and rapidity. In this paper, we discuss the acquisition and analysis of GPR data acquired in the Kunlun Mountain railway tunnel, China. We evaluate the tunnel lining quality and detect the hidden flaws in the lining, which are used to direct the subsequent grouting. Finally, GPR is used to assess the quality of the grouting. The results verify the flexibility and effectiveness of this method.
The role of geomagnetic methods in the detection of mineral deposits at El‐Hody area, south‐eastern Aswan, Egypt
Authors: Rabeh T. , El Faragawy K.O. , Miranda J.M. , Monteiro Santos F.A. , Ahmed M.
Published: August 2009

In this study we delineate the subsurface structures within an area of about 840 km2 in south‐western Egypt, using magnetic methods. The main target is to establish the tectonic framework of the studied area and to understand the role of tectonics in the mineralization process. To do so, a land magnetic survey was conducted, complemented with available aeromagnetic data. This data set is processed using a series of techniques, namely, trend analysis, Werner deconvolution and 2.5 direct modelling. Results indicate that the most predominant tectonic trends are NW–SE, NE–SW and E–W directions. The depth to the basement rocks ranges from 0 to 1.3 km. These results agree with the drilled well data. We show a good correlation between the structures deduced from the magnetic analysis and the known mineral distributions. We conclude that mineralization is structurally controlled by faulting, probably as the result of hydrothermal circulation on fault planes.
Investigation of underground cavities in a two‐layer model using the refraction seismic method
Authors: Engelsfeld Tihomir , Šumanovac Franjo , Pavin Nenad
Published: August 2009

This paper presents a new approach to the investigation of underground cavities. Our technique is based on the refraction seismic method. We have studied a two‐dimensional, two‐layer geological model. In our model, the lower seismic velocity layer is situated above the higher seismic velocity layer, with a circular cavity positioned within the upper layer. We have investigated the influence exerted by the cavity on the first arrivals of seismic waves. The obtained traveltimes are solutions of the eikonal equation and are presented using the time‐distance graph. All refracted waves encountering the cavity have to circumvent it, as it represents an impediment to the propagation of seismic energy. This circumvention causes delays in the first arrivals of the seismic waves at the surface as compared to traveltimes with no cavity present. These delays create a characteristic shape of the time‐distance graph, characterized by the peak point in which the plot line has a discontinuous change. Using this graph and analysing the delays of the first arrivals, we have derived expressions for determining both the position and size of the circular cavity. The practical application of the derived relations has been tested on a model test site built in a natural rock setting. This simple method indicates the presence of the cavity. The accuracy of the calculated cavity parameters: the horizontal position , the depth and cavity radius depends on the geophone spacing. For geophone spacing equal to or less than the cavity radius, the accuracy of the method is shown to be acceptable. The maximal estimated error is equal to a half geophone spacing. Finally, we have demonstrated that this method is also applicable in the detection of non‐circular cavities.
Geotechnical analysis and 4D GPR measurements for the assessment of the risk of sinkholes occurring in a Polish mining area
Authors: Marcak Henryk , Golebiowski Tomislaw , Tomecka‐Suchon Sylwia
Published: August 2009

The study presented in this paper concerns georadar investigations at a selected former coal mining site in Upper Silesia (Poland) where the risk of sinkhole appearance is high. The results of 3D GPR surveys obtained in three measurement sessions in December 1997, October 2006 and March 2007 were interpreted. The 4D interpretation, i.e., a time‐space analysis, allowed for the identification of loose zones in the ground and fractured zones of the rock mass, which might be a source of sinkhole creation. After the first measurement session, on the basis of the GPR survey results, a dangerous, fractured zone in the ground was localized. This zone was confirmed by a borehole. Between the second and third sessions, a large sinkhole appeared on site, as predicted on the basis of georadar investigations. The geomechanical analyses presented in this paper explain the development of the fractured zones over the earlier mining excavations. Such zones accumulate water and high contrasts of dielectrical permittivity appear, allowing the use of the GPR method for the location of these zones.
Processing and Presentation of Variant Surface Glycoprotein Molecules to T Cells in African Trypanosomiasis
Authors: Dagenais Taylor R. , Freeman Bailey E. , Demick Karen P. , Paulnock Donna M. , Mansfield John M.
Published: August 2009

Th1 cell responses to the variant surface glycoprotein (VSG) of African trypanosomes play a critical role in controlling infection through the production of IFN-γ, but the role of APCs in the induction and regulation of T cell-mediated protection is poorly understood. In this study, we have investigated the Ag presentation capabilities of dendritic cells (DCs) and macrophages during early trypanosome infection in relatively resistant responder and susceptible nonresponder mouse strains. Splenic DCs appeared to be the primary cell responsible for activating naive VSG-specific Th cell responses in resistant responder animals through the coordinated up-regulation of costimulatory molecules, secretion of IL-12, and presentation of VSG peptides to T cells in vivo. Splenic DC depletion and the down-regulation of costimulatory markers on splenic macrophages were observed in susceptible animals and may be associated with the inability of these animals to elicit a significant VSG-specific T cell response. In contrast to splenic APCs, peritoneal macrophages secreted NO, failed to activate naive Th cells in vitro, and presented relatively low levels of VSG peptides to T cells in vivo. Thus, VSG-specific Th1 cell responses may be determined by tissue- and cell-specific differences in Ag presentation. Additionally, all APCs from resistant and susceptible strains displayed a reduced ability to process and present newly encountered exogenous Ag, including new VSG molecules, during high parasitemia. Thus, initial uptake of VSG (or other trypanosome factors) may interfere with Ag presentation and have dramatic consequences for subsequent T cell responses to other proteins.
Modulation of Single-Cell IgG Secretion Frequency and Rates in Human Memory B Cells by CpG DNA, CD40L, IL-21, and Cell Division
Authors: Henn Alicia D. , Rebhahn Jonathan , Brown Miguel A. , Murphy Alison J. , Coca Mircea N. , Hyrien Ollivier , Pellegrin Tina , Mosmann Tim , Zand Martin S.
Published: August 2009

During the recall response by CD27+ IgG class-switched human memory B cells, total IgG secreted is a function of the following: 1) the number of IgG-secreting cells (IgG-SC), and 2) the secretion rate of each cell. In this study, we report the quantitative ELISPOT method for simultaneous estimation of single-cell IgG secretion rates and secreting cell frequencies in human B cell populations. We found that CD27+ IgM− memory B cells activated with CpG and cytokines had considerable heterogeneity in the IgG secretion rates, with two major secretion rate subpopulations. BCR cross-linking reduced the frequency of cells with high per-cell IgG secretion rates, with a parallel decrease in CD27high B cell blasts. Increased cell death may account for the BCR-stimulated reduction in high-rate IgG-SC CD27high B cell blasts. In contrast, the addition of IL-21 to CD40L plus IL-4-activated human memory B cells induced a high-rate IgG-SC population in B cells with otherwise low per-cell IgG secretion rates. The profiles of human B cell IgG secretion rates followed the same biphasic distribution and range irrespective of division class. This, along with the presence of non-IgG-producing, dividing B cells in CpG plus cytokine-activated B memory B cell populations, is suggestive of an on/off switch regulating IgG secretion. Finally, these data support a mixture model of IgG secretion in which IgG secreted over time is modulated by the frequency of IgG-SC and the distribution of their IgG secretion rates.
Sequential, Ordered Acquisition of Antibodies to Plasmodium falciparum Erythrocyte Membrane Protein 1 Domains
Authors: Cham Gerald K. K. , Turner Louise , Lusingu John , Vestergaard Lasse , Mmbando Bruno P. , Kurtis Jonathan D. , Jensen Anja T. R. , Salanti Ali , Lavstsen Thomas , Theander Thor G.
Published: August 2009

The binding of erythrocytes infected with mature blood stage parasites to the vascular bed is key to the pathogenesis of malignant malaria. The binding is mediated by members of Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family. PfEMP1s can be divided into groups, and it has previously been suggested that parasites expressing group A or B/A PfEMP1s are most pathogenic. To test the hypothesis that the first malaria infections in infants and young children are dominated by parasites expressing A and B/A PfEMP1s, we measured the plasma Ab level against 48 recombinant PfEMP1 domains of different groupings in 1342 individuals living in five African villages characterized by markedly different malaria transmission. We show that children progressively acquire a broader repertoire of anti-PfEMP1 Abs, but that the rate of expansion is governed by transmission intensity. However, independently of transmission intensity, Abs are first acquired to particular duffy binding ligand-like domains belonging to group A or B/A PfEMP1s. The results support the view that anti-PfEMP1 Ab responses effectively structure the expenditure of the repertoire of PfEMP1 maintained by the parasite. Parasites expressing certain group A and B/A PfEMP1s are responded to first by individuals with limited previous exposure, and the resulting Abs reduce the fitness and pathogenicity of these parasites during subsequent infections. This allows parasites expressing less pathogenic PFEMP1s to dominate during later infections. The identification of PfEMP1 domains expressed by parasites causing disease in infants and young children is important for development of vaccines protecting against severe malaria.
Genetic Control of Severe Egg-Induced Immunopathology and IL-17 Production in Murine Schistosomiasis
Authors: Smith Patrick M. , Shainheit Mara G. , Bazzone Lindsey E. , Rutitzky Laura I. , Poltorak Alexander , Stadecker Miguel J.
Published: August 2009

Infection with the trematode parasite Schistosoma mansoni results in a distinct heterogeneity of disease severity, both in humans and in an experimental mouse model. Severe disease is characterized by pronounced hepatic egg-induced granulomatous inflammation in a proinflammatory cytokine environment, whereas mild disease corresponds with reduced hepatic inflammation in a Th2 skewed cytokine environment. This marked heterogeneity indicates that genetic differences play a significant role in disease development, yet little is known about the genetic basis of dissimilar immunopathology. To investigate the role of genetic susceptibility in murine schistosomiasis, quantitative trait loci analysis was performed on F2 progeny derived from SJL/J and C57BL/6 mice, which develop severe and mild pathology, respectively. In this study, we show that severe liver pathology in F2 mice 7 wk after infection significantly correlated with an increase in the production of the proinflammatory cytokines IL-17, IFN-γ, and TNF-α by schistosome egg Ag-stimulated mesenteric lymph node cells. Quantitative trait loci analysis identified several genetic intervals controlling immunopathology as well as IL-17 and IFN-γ production. Egg granuloma size exhibited significant linkage to two loci, D4Mit203 and D17Mit82, both of which were inherited in a BL/6 dominant manner. Furthermore, a significant reduction of hepatic granulomatous inflammation and IL-17 production in interval-specific congenic mice demonstrated that the two identified genetic loci have a decisive effect on the development of immunopathology in murine schistosomiasis.
Biological Effects of Electromagnetic and Particle Radiation
Authors: Kiefer Jürgen
Published: August 2009

The article contains sections titled:

Introduction

Radiation Types and Sources

Interaction with Biosystems at the Physical Level

Ionizing Radiation

Electromagnetic Radiation

Particle Radiation

Optical Radiation

Radio Frequency and Microwaves

Deposition of Energy

Ionizing Radiation

UVand Visible Radiation

Infrared

Radio Frequency and Microwaves

Effects on Molecules of Biological Importance and Cell Organelles

Water

Photochemistry and Radiation Chemistry ofDNA

Chromosomal Aberrations

Membranes

Effects of Heat Treatment

Specific Molecular Aspects of Radio Frequency and Microwave Actions

Cellular Effects

Experimental Endpoints of Cellular Radiation Action

Survival

Mutations

Neoplastic Transformation

Modifications of Cellular Radiation Effects

The Temporal Pattern of Exposure

Chemical Protectors and Sensitizers

Repair Processes

Radiation Quality

“Nonclassical” Effects in Cellular Radiobiology: Bystander Effect, Genomic Instability, Low Dose Sensitivity, and Adaptive Response

Heat Effects at the Cellular Level

Specific Cellular Effects of Radio Frequency and Microwaves

Organ and Whole‐Body Effects

Acute Effects

Skin

Eye

Nervous System and Other Organs

Radiation Syndromes and Lethality

Radiation and Progeny

Fertility

Teratogenic Effects

Genetic Effects

Radiation Cancerogenesis

Ultraviolet Radiation

Ionizing Radiation

Tissue and Whole‐Body Effects of Infrared Radiation

Tissue and Whole‐Body Effects of Radio Frequency and Microwaves

Applied Radiation Biology

Molecular Techniques

Action Spectroscopy

Molecular Weight Determination by “Radiation Inactivation”

Radiation Disinfection and Sterilization

Therapeutic Applications

Nonmalignant Diseases

Cancer Therapy

Biodosimetry

FluorescenceIn situHybridization (FISH) for Chromosomal Translocations

ESRDosimetry

Radioecology, Radiation Protection, and Guidelines

Radioecology

Nonionizing Radiations

Ionizing Radiation

Principles of Radiation Protection Regulations

Ionizing Radiations

Nonionizing Radiations
Biological Effects of Sound and Ultrasound
Authors: Nyborg Wesley L.
Published: August 2009

At frequencies mostly in the megahertz range, ultrasound has become indispensable in diagnostic medicine. Sound over a wide frequency range is being used increasingly in therapeutic applications, including drug delivery. Much research has been carried out to study biological effects of this agent, especially, ultrasound, to seek understanding of mechanisms for them. Since sonic energy is converted into heat as it passes through tissues, temperature elevation is an important mechanism. Another important kind of mechanism, calledcavitation, is important when small gas bubbles are present, as is often true duringin vivoexposures of cell suspensions. If the pressure amplitude is modest, the action may be harmless, or even beneficial by making cells temporarily permeable allowing drug transfer. If it is high, the action may be violent and cause permanent damage. The importance of cavitation during applications of diagnostic ultrasound has greatly increased during the last decade because of the widespread use of “contrast agents”. These are small specially coated gas bubbles, which are injected into the blood of a patient to improve image contrast. Whether cavitation occurs or not during an application, sonic fields can produce effectsviatime‐averaged forces and fluid motions known asradiation forceandacoustic streaming(ormicrostreaming). The present chapter is a review of current knowledge on effects that can be produced by sonic fields and causes of these effects.
Radiationless Auger‐Like Electronic Transitions in Biomolecules: Bio‐Auger Process
Authors: Bohr Henrik G. , Malik F. Bary
Published: August 2009

Nonradiative relaxation process caused by the interaction between electrons in biomolecules following radiative absorption is discussed herein. The process is akin to Auger transitions in atoms to fill K, L, or M shell vacancies. Such Auger transitions in light elements are much faster than the radiative transition rate, and half‐lives could be in femtoseconds, as observed in many recent biomolecules being exposed to laser beams. After a brief introduction, the basic theory of Auger and electromagnetic transitions in atomic systems and the calculations based on that indicating dominance of the Auger process over the radiative one are presented in Section 2.2. The similarity and differentiation between the Auger process in atomic systems and similar ones in biomolecules, termed asBio‐Auger processes, are presented in Section 2.3. The single orbital theory and the estimate of the timescale associated with Bio‐Auger processes are noted in Section 2.4, followed by a section on charge or electronic transfer associated with the Bio‐Auger process. In the last section, experimental evidence of the occurrence of the Bio‐Auger process after biomolecules are exposed to ultraviolet (UV) radiation is presented. In particular, calculations indicating the occurrence of electronic excited states in the energy range of UV radiation are noted. It is pointed out that (i) nonradiative transitions of Bio‐Auger type might be preventing cancer in biotissues exposed to the UV part of solar radiation; (ii) dark structures reported in exposing biomolecules to laser beam are electronic charge transfer; (iii) Bio‐Auger processes may lead to charge transfer of electrons from peridinin to chlorophyll‐ain peridinin‐chlorophyll‐a protein (PCP) complex; and (iv) Bio‐Auger processes lead to de‐dimerization of thymine duplex formed in UV activated thymine bases in DNA as it comes in contact with optically activated cofactor riboflavin.
Electron Interactions and Currents in
CFT
, a Current Functional Theory Applied to Molecules
Authors: Bang Jens M. , Bohr Henrik G. , da Providencia Joao
Published: August 2009

Most of the quantum mechanical calculations of electronic structures of molecules are carried out in a stationary frame where the wave functions of the electrons in the molecule are optimized into a ground state configuration. If one, however, wishes to obtain a more dynamic description of molecules on the electronic level and if one wishes to find the spectrum of excited electron states, one will have to employ a time‐dependent quantum mechanical methodology. In the following sections, we introduce a time‐dependent quantum formalism that can give a dynamic treatment of the electronic systems and that can also take care of the calculation of excited states. Besides that, we shall propose rigorous expressions of exchange correlation potentials in order to get more reliable suggestions for the molecular orbitals.
Exploring Excited State Processes in Photosynthesis — Features of Photosynthetic Light Harvesting
Authors: Sundstrom Villy
Published: August 2009

Photosynthesis is the process by which light energy is converted into chemical energy by plants, algae, and photosynthetic bacteria. For this, highly specialized pigment–proteins have evolved, which capture the light and transform the short‐lived excited states of pigment molecules into a stable transmembrane potential. By close scrutiny of organization and processes of the photosynthetic pigment systems, a number of “design principles” can be recognized. By combining knowledge about structure and light converting energy and electron transfer processes, we can identify the most important features for efficient photosynthetic solar energy conversion.
Protein Dynamics — Concepts and Experimental Tools
Authors: Frauenfelder Hans
Published: August 2009

Most textbooks and publications show proteins in a unique structure and naked, without hydration shell and bulk environment. In reality, proteins can assume a very large number of different conformations. They fluctuate continuously and are controlled by the hydration shell and the solvent. Without these fluctuations, proteins could not work. This chapter gives a brief overview of protein dynamics and cites references where more information can be found.
Models of Membrane Fusion
Authors: May Sylvio
Published: August 2009

The fusion of biomembranes is an ubiquitous event in living organisms encountered in diverse situations, such as intracellular trafficking, recycling, fertilization, and infections by enveloped viruses. Even though each specific type of biological fusion is regulated by particular fusion proteins, it always involves the merger of two lipid bilayers. Even in the absence of proteins, bare lipid bilayers can be induced to undergo fusion. The question whether different types of fusion are variants of one or several universal fusion mechanisms has received much attention, but is not finally answered. At present, the most promising candidate is the stalk‐pore fusion pathway, which involves several lipid‐based fusion intermediates. We give an overview of common fusion types, current knowledge of corresponding fusion mechanisms, and efforts to model membrane fusion. The latter includes both phenomenological modeling and computer simulations.
R
aman Spectroscopy in Virus Structure Analysis
Authors: Němeček Daniel , Thomas George J.
Published: August 2009

The structures of complex biological assemblies, such as viruses, and the molecular mechanisms governing virus assembly
in vivo
and
in vitro
require investigation by multiple biophysical techniques. One such technique is Raman spectroscopy, which is particularly useful for probing key steps in the assembly pathways of viruses and for elucidating the molecular structures of viral proteins and nucleic acids. Here, we briefly review the implementation of methods of Raman spectroscopy, including ultraviolet resonance Raman (UVRR) spectroscopy and polarized Raman spectroscopy as structural probes of native viruses, viral precursor assemblies and their constituent proteins, and nucleic acids. We illustrate the powerful analytical approaches of singular value decomposition (SVD) and polarized Raman microspectroscopy for unique quantitative assessments of viral protein structures. Attention is focused on recent applications to bacterial viruses (bacteriophages) of icosahedral (P22 and HK97) and cylindrical (fd, Pf1, Pf3, and PH75) capsid architectures. Methods of Raman spectroscopy provide novel and unique insights into viral macromolecular structures and their transformations that are essential to morphogenesis.
X‐Ray Methods for Investigation of Structures of Lipid Assemblies
Authors: Huang Huey W. , Yang Lin
Published: August 2009

One remarkable characteristic of lipid–water mixtures is their ability to combine in one phase a periodically ordered long‐range organization in one, two, or three dimensions and a disordered short‐range conformation in the unit cells. This unique property makes X‐ray methods ideally suited for the structural determination of lipid assemblies. The unit cell could be a lipid bilayer or a lipidic structure that might occur during a biological process such as membrane fusion or pore formation. In this chapter, we describe methods for resolving the electron density distributions in the unit cells of various lipidic phases, including the lamellar, hexagonal, distorted hexagonal, and rhombohedral phases. The biophysical applications are to determine the structural changes caused by the inclusion of proteins to lipid bilayers. The illustrated examples include changes of the bilayer thickness, distribution of proteins or lipid components in membranes, and monolayer configurations related to membrane fusion and pore formation. The technical sections include sample preparation, diffraction geometry, data reduction, and methods for solving the phase problem, in particular a method of multiwavelength anomalous dispersion uniquely suited for solving lipidic structures.
Ion Channels
Authors: Andersen Olaf S. , Ingólfsson Helgi I. , Lundbæk Jens A.
Published: August 2009

Ion channels catalyze the transmembrane movement of small inorganic ions across biological membranes. They do so by forming continuous, hydrophilic pores through which ions can cross the barrier imposed by the lipid bilayer hydrophobic core. Ion channels serve many functions: they underlie the changes in membrane potential that control many cell functions, including the propagated electrical signaling (the action potentials) in electrically excitable cells; they allow for the bulk movement of ions across cell membranes. In this chapter, we summarize key features of ion channels, with special emphasis on the channels in the plasma membrane — their structure and catalytic power, the generation of membrane potential changes, the regulation (or gating) that underlies normal channel function, and how channel function can be modulated by small molecules.
Ketonization of 1,5‐Cyclooctadiene by Nitrous Oxide
Authors: Ivanov Dmitry P. , Dubkov Konstantin A. , Babushkin Dmitry E. , Semikolenov Sergey V. , Panov Gennady I.
Published: August 2009

The kinetics and mechanism of the liquid phase ketonization of 1,5‐cyclooctadiene (COD) by nitrous oxide have been studied. The reaction proceeds without catalyst in the temperature range 473–553 K with the activation energy 113 kJ mol−1 and is first order with respect to the initial reactants. The mechanism includes consecutive ketonization of two CC bonds in the COD molecule, with the intermediate formation of an unsaturated monoketone (MK). Further ketonization of MK leads to two isomeric diketones (DK): 1,4‐ and 1,5‐cyclooctanedione. The 1,5‐DK is a stable final product while the 1,4‐DK undergoes further intramolecular aldol transformation leading to two bicyclic compounds, that retain the same number of carbon atoms. The distribution of mono‐ and diketones in the course of reaction is described by theoretical dependences pointing to identical reactivities of the CC double bonds residing in COD and MK molecules. The ketonization of COD by nitrous oxide exemplifies a prospective way for the preparation of valuable organic products in perfect harmony with the strategy of green chemistry.
TEMPO and Carboxylic Acid Functionalized Imidazolium Salts/Sodium Nitrite: An Efficient, Reusable, Transition Metal‐Free Catalytic System for Aerobic Oxidation of Alcohols
Authors: Miao Cheng‐Xia , He Liang‐Nian , Wang Jin‐Quan , Wang Jing‐Lun
Published: August 2009

An effective catalytic system comprising a 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) functionalized imidazolium salt ([Imim‐TEMPO]+ X−), a carboxylic acid substituted imidazolium salt ([Imim‐COOH]+ X−), and sodium nitrite (NaNO2) was developed for the aerobic oxidation of aliphatic, allylic, heterocyclic and benzylic alcohols to the respective carbonyl compounds with excellent selectivity up to >99%, even at ambient conditions. Notably, the catalyst system could preferentially oxidize a primary alcohol to the aldehyde rather than a secondary alcohol to the ketone. Moreover, the reaction rate is greatly enhanced when a proper amount of water is present. And a high turnover number (TON 5000) is achieved in the present transition metal‐free aerobic catalytic system. Additionally, the functionalized imidazolium salts are successfully reused at least four times. This process thus represents a greener pathway for the aerobic oxidation of alcohols into carbonyl compounds by using the present task‐specific ionic liquids in place of the toxic and volatile additive, such as hydrogen bromide, bromine, or hydrogen chloride (HBr, Br2 or HCl), which is commonly required for the transition metal‐free aerobic oxidation of alcohols.
Impact of surface tension and viscosity on solids motion in a conical high shear mixer granulator
Authors: Fan Xianfeng , Yang Zhufang , Parker David J. , Ng Boonho , Ding Yulong , Ghadiri Mojtaba
Published: August 2009

Surface tension and viscosity are the important properties of liquid binders affecting wet granulation processes. They could be used to control solids flow pattern and relative motion of particles for controlling wetting, granule growth, consolidation, and breakage. This study aims to investigate experimentally the impacts of the two properties with a conical high shear granulator. The results show significant effects of viscosity and surface tension on solids flow pattern and relative motion of particles. The relative importance of the two parameters, the surface tension and the viscosity, are found to vary with the axial and radial positions in the granulator. For example, the viscosity force decreases with an increase in the bed height in the axial direction (vertical plane). The viscosity force between particles coated with PEG4000 solution is in mN order, whereas that between particles coated with ethanol and water is in μN order. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Theoretical study of a membrane reactor for the water gas shift reaction under nonisothermal conditions
Authors: Adrover María E. , López Eduardo , Borio Daniel O. , Pedernera Marisa N.
Published: August 2009

A simulation of a membrane reactor for the water gas shift reaction is carried out by means of a 1D pseudo‐homogeneous nonisothermal mathematical model. The composite membrane consists of a dense layer of Pd (selective to H2) supported over a porous ceramic layer. The effect of temperature, overall heat‐transfer coefficient, and mode of operation on the membrane reactor performance and stability are analyzed, and the results obtained are compared with those corresponding to a reactor with no hydrogen permeation. © 2009 American Institute of Chemical Engineers AIChE J, 2009
A novel dual circulating fluidized bed system for chemical looping processes
Authors: Pröll Tobias , Kolbitsch Philipp , Bolhàr‐Nordenkampf Johannes , Hofbauer Hermann
Published: August 2009

A fluidized bed system combining two circulating fluidized bed reactors is proposed and investigated for chemical looping combustion. Direct hydraulic communication of the two circulating fluidized bed reactors via a fluidized loop seal allows for high rates of global solids circulation and results in a stable solids distribution in the system. A 120 kW fuel power bench scale unit was designed, built, and operated. Experimental results are presented for natural gas as fuel using a nickel‐based oxygen carrier. No carbon was lost to the air reactor under any conditions operated. It is shown from fuel power variations that a turbulent/fast fluidized bed regime in the fuel reactor is advantageous. Despite the relatively low riser heights (air reactor: 4.1 m, fuel reactor: 3.0 m), high CH4conversion and CO2yield of up to 98% and 94%, respectively, can be reported for the material tested. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Experimental investigation on evaporation of urea‐water‐solution droplet for SCR applications
Authors: Wang Tae Joong , Baek Seung Wook , Lee Seung Yeol , Kang Dae Hwan , Yeo Gwon Koo
Published: August 2009

The evaporation behavior of urea‐water‐solution (UWS) droplet was investigated for application to urea‐selective catalytic reduction (SCR) systems. A number of experiments were performed with single UWS droplet suspended on the tip of a fine quartz fiber. To cover the temperature range of real‐world diesel exhausts, droplet ambient temperature was regulated from 373 to 873 K using an electrical furnace. As a result of this study, UWS droplet revealed different evaporation characteristics depending on its ambient temperature. At high temperatures, it showed quite complicated behaviors such as bubble formation, distortion, and partial rupture after a linear D2‐law period. However, as temperature decreases, these phenomena became weak and finally disappeared. Also, droplet diminishment coefficients were extracted from transient evaporation histories for various ambient temperatures, which yields a quantitative evaluation on evaporation characteristics of UWS droplet as well as provides valuable empirical data required for modeling or simulation works on urea‐SCR systems. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Synthesis, structure, and selective separation behavior of copper‐imprinted microporous polymethacrylate beads
Authors: Hoai Nguyen To , Kim Dukjoon
Published: August 2009

Metal ion‐imprinted polymethacrylate beads with sizes ranging from 100 to 300 μm were prepared by suspension polymerization for the application of selective separation of target metal ions. The metal ion contacting area of the beads was enlarged via pore formation (BET 425 m2/g) using toluene as a porogenic agent. The synthesis of the copper‐imprinted porous beads was verified using FTIR, SEM, and ESCA. Separation capacity and selectivity were investigated carrying out column separation experiments. The selective adsorption behavior of the imprinted beads was significantly affected by flow rate, pH, and metal ion concentration in the solution. Adsorption of the copper ion, the template metal ion, onto the beads was highly selective, compared with other ions such as nickel and zinc, with the selective coefficients at approximately 5–10. The microporous particles possessing such high selectivity has a potential application as novel column packing materials especially requiring high selective efficiency, which is usually not achievable by commercial ion exchange resins. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Beryllium lymphocyte proliferation test surveillance identifies clinically significant beryllium disease
Authors: Mroz Margaret M. , Maier Lisa A. , Strand Matthew , Silviera Lori , Newman Lee S.
Published: August 2009

Background

Workplace surveillance identifies chronic beryllium disease (CBD) but it remains unknown over what time frame mild CBD will progress to a more severe form.

Methods

We examined physiology and treatment in 229 beryllium sensitization (BeS) and 171 CBD surveillance‐identified cases diagnosed from 1982 to 2002. Never smoking CBD cases (81) were compared to never smoking BeS patients (83) to assess disease progression. We compared CBD machinists to non‐machinists to examine effects of exposure.

Results

At baseline, CBD and BeS cases did not differ significantly in exposure time or physiology. CBD patients were more likely to have machined beryllium. Of CBD cases, 19.3% went on to require oral immunosuppressive therapy. At 30 years from first exposure, measures of gas exchange were significantly worse and total lung capacity was lower for CBD subjects. Machinists had faster disease progression as measured by pulmonary function testing and gas exchange.

Conclusions

Medical surveillance for CBD identifies individuals at significant risk of disease progression and impairment with sufficient time since first exposure. Am. J. Ind. Med. 52:762–773, 2009. © 2009 Wiley‐Liss, Inc.
Gene therapy and protein therapy of ectodermal dysplasias: A perspective
Authors: Gaide Olivier
Published: August 2009

Ectodermal dysplasias (EDs) form a complex and heterogeneous group of diseases currently defined and classified according to their clinical symptoms. The characterization, for several EDs, of the molecular events underlying their development, not only challenges this classification but also opens the door to new therapeutic options such as gene or protein therapy. This article provides a concise overview of the most recent successes and failures of this new type of treatment and sets in perspective how the specificities of given EDs will influence their feasibility in the near future. It makes the case for the need of new classification of EDs that is based on our most recent knowledge of the molecular basis of these diseases. © 2009 Wiley‐Liss, Inc.
2008 International Conference on Ectodermal Dysplasias Classification: Conference report
Authors: Salinas Carlos F. , Jorgenson Ronald J. , Wright J. Timothy , DiGiovanna John J. , Fete Mary D.
Published: August 2009

There are many ways to classify ectodermal dysplasia syndromes. Clinicians in practice use a list of syndromes from which to choose a potential diagnosis, paging through a volume, such as Freire‐Maia and Pinheiro's corpus, matching their patient's findings to listed syndromes. Medical researchers may want a list of syndromes that share one (monothetic system) or several (polythetic system) traits in order to focus research on a narrowly defined group. Special interest groups may want a list from which they can choose constituencies, and insurance companies and government agencies may want a list to determine for whom to provide (or deny) health‐care coverage. Furthermore, various molecular biologists are now promoting classification systems based on gene mutation (e.g., TP63‐associated syndromes) or common molecular pathways. The challenge will be to balance comprehensiveness within the classification with usability and accessibility so that the benefits truly serve the needs of researchers, health‐care providers, and ultimately the individuals and families directly affected by ectodermal dysplasias. It is also recognized that a new classification approach is an ongoing process and will require periodical reviews or updates. Whatever scheme is developed, however, will have far‐reaching application for other groups of disorders for which classification is complicated by the number of interested parties and advances in diagnostic acumen. Consensus among interested parties is necessary for optimizing communication among the diverse groups whether it be for equitable distribution of funds, correctness of diagnosis and treatment, or focusing research efforts. © 2009 Wiley‐Liss, Inc.
Katalytische C‐C‐, C‐N‐ und C‐O‐Ullmann‐Kupplungen
Authors: Monnier Florian , Taillefer Marc
Published: August 2009

Kupferkatalysierte Ullmann‐Kondensationen sind Schlüsselreaktionen in der organischen Synthese zur Bildung von Kohlenstoff‐ Heteroatom‐ und Kohlenstoff‐Kohlenstoff‐Bindungen. Die mit diesen Methoden erhältlichen Strukturmotive sind in biologisch aktiven Molekülen und vielen Materialvorstufen weit verbreitet. Dementsprechend waren intermolekulare Ullmann‐Reaktionen zur Kupplung von Aryl‐ und Vinylhalogeniden mit N‐, O‐ und C‐Nucleophilen Gegenstand zahlreicher Studien, und dieser Kurzaufsatz beleuchtet die aktuellsten und wichtigsten Entwicklungen auf diesem Gebiet seit 2004.
Effect of ceramic nanoadditive content and type on the rheological properties of poly(vinyl alcohol) spinning solutions
Authors: Boguń Maciej , Mikołajczyk Teresa
Published: August 2009

Rheological properties of aqueous PVA solutions within a wide concentration range have been examined to select a concentration at which apparent dynamic viscosity is suitable for fiber spinning from solution by the wet process. The rheological properties of PVA solutions containing various quantities of nanosilica and nanohydroxyapatite were assessed. It has been found that an increase in the quantity of both types of nanoadditives from 1 to 5% brings about a decrease in the value of the rheological parameter n and enhances the polymeric character of the fluid. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Natural rubber/poly(acrylic acid) semi‐interpenetrating polymer network membranes for the pervaporation of water–ethanol mixtures
Authors: Amnuaypanich Sittipong , Kongchana Nuchjarin
Published: August 2009

Pervaporation membranes for the dehydration of water–ethanol mixtures were prepared from a semi‐interpenetrating polymer network (semi‐IPN) of natural rubber (NR) and crosslinked poly(acrylic acid) (PAA). The swelling studies revealed that hydrophilic PAA present in the semi‐IPN membranes caused the membranes to swell greatly in water. The swelling degree of the membranes in water was significantly affected by the amount ratio between the hydrophobic NR and the hydrophilic PAA. The sorption experiments of the NR/PAA membranes in various concentrations of water–ethanol mixtures suggested the preferential sorption to water. However, for the membrane with high PAA content, the water sorption selectivity decreased considerably at high water concentration of water–ethanol mixtures because the membrane was in the highly swollen state. Pervaporation separations of water–ethanol mixtures using NR/PAA membranes were performed and it was found that at low water concentrations of feed mixtures, increasing the PAA content of the membrane can enhance both water permeation flux and selectivity. Additionally, under low feed water concentration, increasing the feed temperature would increase the water flux with the decreasing of the ethanol flux. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Influence of polyacrylate/titanium dioxide composite particles on the antiaging performance of polycarbonates
Authors: Han Shi‐Min , Yang Ming‐Jiao , Gao Wei‐Bin , Tang Ming‐Jing , Jiang Long , Dan Yi
Published: August 2009

Polycarbonate (PC) and PC modified by polyacrylate/TiO2 composite particles were exposed both in an outdoor environment with typical humid and hot climatic conditions in the Jiangjin area and in an indoor hygrothermal environment for accelerated aging. Then, the effects of the polyacrylate/TiO2 composite particles on the antiaging performance of PC were investigated by measurement of the mechanical properties of PC before and after aging. The results show that the mechanical properties of PC decreased a lot after aging by the outdoor environment of the Jiangjin area. After accelerated aging by the indoor hygrothermal environment, the tensile strength and the bending strength of PC increased a little, and the elongation at break of PC decreased. The polyacrylate/TiO2 composite particles effectively increased the elongation at break of PC aged by the hygrothermal environment and outdoor aging. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Large‐scale synthesis of polyaniline nanofibers based on renewable resource molecular template
Authors: Anilkumar P. , Jayakannan M.
Published: August 2009

We report reproducible large‐scale synthesis of polyaniline (PANI) nanofibers up to 100 g scale via micelle mediated soft template approach. A unique built‐in amphiphilic azobenzenesulfonic acid based on renewable resource dopant was synthesized for large‐scale production of PANI nanofibres. The amphiphilic surfactant exists as 4.3 nm micelle in water and it self‐organized with aniline to form long cylindrical aggregates, which template for PANI nanofibers. The PANI nanofibers were found soluble in water and organic solvents and they were characterized by 1H‐NMR, FT‐IR, and viscosity techniques. The mechanism of the PANI nanofiber formation was investigated by dynamic light scattering, scanning electron microscopy, and high resolution transmission electron microscopy. The width of the nanofibers was precisely controlled from 130–200 nm with length up to ∼ 5 μm. The absorption spectroscopic analysis of nanofibers in water revealed that the large‐scale samples (10, 50, and 100 g) were found to posses expanded chain conformation compared to that of 1 g scale sample. The wide angle X‐ray diffraction patterns showed two new peaks at lower angles at d spacing of 25.5 and 13.6 Å corresponding to lamellar ordering of PANI chains followed by interdigitation of the amphiphilic dopant in the nanofibers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Influence of hybridization of glass fiber and talc on the mechanical performance of polypropylene composites
Authors: Morelli Carolina L. , Pouzada António S. , Sousa José A.
Published: August 2009

The effect of the hybridization of short glass fibers (GFs) and talc mineral filler on the tensile mechanical performance of injection‐molded propylene‐ethylene copolymer composites (PPcop) with and without weld lines (WLs) was studied in this work. The fibrous reinforcement imparts high‐tensile stiffness and strength to the molding but originates a highly anisotropic composite. The negative effect of this anisotropy is even worse when WLs occur in the molding, as the high aspect ratio GFs tend to be oriented on the weak plane of the WL. Through hybridization of GF and talc, combined in different proportions, it is possible to obtain improved mechanical properties in comparison to the standard GF reinforced PPcop composites. The combination of GF with talc was shown to be beneficial for the WL strength of PPcop composites, once a synergism effect was achieved with the expected optimization of the fibers/particles packing efficiency of the hybrid reinforcement. At a given constant total reinforcement concentration, the experimental data of both tensile modulus and strength properties of the hybrid composites without WL were above the predictions derived from the estimated rule of mixtures. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Investigation the jet stretch in PAN fiber dry‐jet wet spinning for PAN‐DMSO‐H2O system
Authors: Zeng Xiaomei , Chen Jiangmin , Zhao Jiongxin , Wu Chengxun , Pan Ding , Pan Ning
Published: August 2009

The jet stretch of dry‐jet wet spun PAN fiber and its effects on the cross‐section shape of fibers were investigated for a PAN‐DMSO‐H2O system. Clearly, the spinning parameters, such as dope temperature, bath concentration, bath temperature, and air gap, all influenced the jet stretch. Also, under uniform conditions, the postdrawing ratio as well as that of jet stretch changed. Under given conditions, as the bath temperature was below 30°C or above 45°C, jet stretch had little effect on the cross‐sectional shapes of PAN fiber. Within the temperature of 30–45°C, fiber's cross‐section shapes change obviously from round over an approximate circular shape into to an elliptical or a flat shape. The scope of jet stretch produced PAN fiber with circular cross‐section was bigger than that in wet spinning. These results indicated that appropriate air gap height, under milder formation conditions in dry‐jet wet spinning, could result in higher jet stretch and higher postdrawing ratio. The appropriate jet stretch and postdrawing ratio could result in circular profile of PAN fiber, which were helpful to produce round PAN precursor with finer size and better properties for carbon fiber. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009