bluuebunny/crossref_metadata_2025 huggingface dataset:
Laboratory Performance of Geogrid-reinforced Soils Subjected to Freezing and Thawing
Authors: Alfaro Marolo C. , Pathak Yadav P.
Published: August 2012

This paper reports results from bench-scale plane-strain laboratory tests conducted in order to investigate the behavior of geogrid-reinforced silt specimens during freezing and thawing cycles. Soil–geogrid interaction was analyzed through comparison of the soil and geogrid strains. Vertical and lateral pressures were applied to the specimens to simulate anisotropic loading conditions in the field. Reinforced and unreinforced specimens were subjected to cycles of freezing (−25°C) and thawing (+23°C) temperatures inside a walk-in temperature-controlled environmental chamber. Measured geogrid strains at the end of 12 freezing-thawing cycles were on the order of 0.57 %. An additional strain of this magnitude in the reinforcement due to the freezing-thawing cycles would have only minimal effect on working strain levels in the design, which range from 1 % to 2 %. However, the strains induced by freezing and thawing can approach working design strains as the number of cycles increases. This could have significant long-term implications if accumulated strains were to overstrain the geogrid. The soil deformations were observed to be mostly horizontal. This pattern of deformations during the freezing and thawing of silt could result in shallow sliding at the face of slopes and embankments. The soil strains were higher than the geogrid strains, indicating relative movements between soil and reinforcement, mostly during thawing.
Sensing and Imaging the State of Effective Stress in a 1-g Shallow Foundation Model
Authors: Kim Kyu-Sun , Tanner William M. , Fratta Dante
Published: August 2012

This paper describes an experimental study for the imaging of effective stresses under a shallow foundation system. S-wave data were collected during several loading stages of the shallow foundation model. S-wave crosshole data were inverted to obtain effective stress distribution images by solving the tomographic imaging problem. To optimize the travel-time tomographic imaging solution of the stress-heterogeneous medium, S-wave data quality, sensor array design, ray tracing algorithm selection, and inversion parameter choice were carefully considered. The experimental results show the practical engineering potential of tomographic imaging techniques for the monitoring of in situ effective stress and the evaluation of design models and effective stress-driven processes.
Protocol for Testing Fouled Railway Ballast in Large-Scale Cyclic Triaxial Equipment
Authors: Ebrahimi Ali , Tinjum James M. , Edil Tuncer B.
Published: August 2012

A testing protocol was developed to measure accumulation of vertical plastic deformation in fouled railway ballast under cyclic traffic loading. Large-scale cyclic triaxial (LSCT) test equipment was constructed to test fouled ballast under various stress conditions. A method of introducing fouling material and moisture to ballast specimens was critical to the resulting deformational behavior. Specimens for LSCT testing should be prepared by mixing ballast with relatively dry fouling material (moisture <5 % for granular fouling and <15 % for clay-based fouling) prior to compaction to prevent a heterogeneous distribution of fouling within the specimen. A full-scale track model experiment (FSTME) was built to determine a representative state of stress (RSS) for railway ballast for use in the LSCT testing. The RSS allows for testing of ballast under consistent stresses to compare the effect of material characteristics of fouling such as fouling content and moisture content. A RSS of 90 kPa (confining) and 300 kPa (deviator) for a train axle load of 264 kN was suggested based on the FSTME results. Measured deformation of fouled ballast using the proposed testing protocol was compared with a published vertical deformation of railway track in a track test section. Results of this study indicate that the proposed testing protocol can simulate the vertical plastic deformation of railway ballast at a specified stress level.
Characterisation of Lightly Stabilised Granular Base Materials by Flexural Beam Testing and Effects of Loading Rate
Authors: Paul D. K. , Gnanendran C. T.
Published: August 2012

This paper presents the results from an experimental study on the characterisation of lightly stabilised granular base materials by monotonic load/displacement flexural beam testing which was carried out on two granular base materials lightly stabilised with 1 % to 3 % cement—fly ash. Effects of the loading/displacement rate on the flexural properties (i.e., flexural strength and stiffness modulus) of the lightly stabilised granular base materials were investigated and they were found to be loading/displacement rate-dependent. The suitability of an improved (newly developed) flexural beam testing setup with internal deflection measurements, which was employed to determine these flexural properties, was also examined. Test results indicate that this improved flexural beam testing setup can be used reliably for characterising lightly stabilised granular base materials.
A New Laser Sensor Volume Measurement System for the Triaxial Testing of Unsaturated Soils
Authors: Zhang X. , Mavroulidou M. , Sutton J. , Cabarkapa Z. , Gunn M. J.
Published: August 2012

The paper demonstrates a novel non-contacting volume change measurement system for triaxial soil testing. The system uses an ultra high accuracy laser displacement sensor that measures water volume changes resulting from the volume change of the specimen during testing. The paper presents the design, working principles, system calibrations, and the validation of the system through comparative measurements of volume changes of soil specimens during triaxial shearing, against results of conventional volume measurement techniques.
Index Puncture Resistance of Geomembranes Using Various Protection Geosynthetics
Authors: Koerner Robert M. , Wong W. K. (Connie) , Koerner George R.
Published: August 2012

The puncturing of geomembranes by stones is unfortunately not uncommon. In order to prevent its occurrence, various geosynthetics have been used as protection materials. Needle punched nonwoven geotextiles (of various unit weights), geonet drainage composites, and geosynthetic clay liners have been used, and all are evaluated in this laboratory puncture study. Results from three standardized puncture test methods (tapered, pin, and pyramid shaped end probes) are compared to one another. The results show that all geomembranes are susceptible to puncture, with increasing thickness providing some, but limited, improvement. Geotextiles clearly show improved puncture protection, and the improvement is in linear proportion to their increasing unit weights. Geonet drainage composites also show improvement essentially in proportion to the unit weights of the geotextiles affixed to the surfaces of the geonet core. Geosynthetic clay liners also provide protection, again in proportion to the unit weight of the associated geotextiles, particularly when the bentonite is hydrated.
Shrinkage-induced Damage Evolution for Concrete Overlay
Authors: Wang Guiming , Kong Yun , Guo Zhanqi , Shui Zhonghe , Leng Zheng
Published: August 2012

In this paper, we investigate the development of stress and the debonding behavior of thin bonded concrete overlays under restrained conditions. The results show us that the fractured mode of a concrete repair system will change clearly along the new concrete with higher shrinkage deformation to crack along the interfacial layer, and with increasing intensity strength, the interfacial layer becomes stronger so that it is hard for the concrete repair system to fail. It is difficult to predict the exact crack pathway of a concrete repair system unless the condition of the meso-structure is known.
Investigation of Interaction between the Silicone Rubber Sealant and Concrete Substrate
Authors: Liu Jiesheng , Wu Shaopeng , Lu Haijun
Published: August 2012

This investigation aimed to study the interaction between concrete substrate and silicone rubber sealant. Several surface treatments were applied in order to obtain different levels of surface roughness in concrete substrates. The bond tensile test showed that abrasion and solvent cleaning methods improved the bond strength relative to that of untreated substrates. The effects of silane coupling agents on the bond strength was studied via two methods of application of the coupling agent, namely, (a) pre-treatment of concrete substrate in an aqueous solution of silane, and (b) adding silane to the silicone rubber sealant as an integral blend additive. No significant differences in bonding values were noted between the two methods. An increase in the amount of silane coupling agent increased the bond strength of the silicone rubber sealant, but beyond a certain point, further increases in the amount of silane lowered the bond strength. As the amount of silanes increased, the failure mode of the samples changed from adhesive failure to cohesive failure. Scanning electron microscopy and contact angle methods were employed to investigate the interface. The results strongly suggest that interface adhesion and treatments are crucial factors in creating a durable bond interface between substrate and sealant.
Effect of Layered Double Hydroxides (LDHs) on Aging Properties of Bitumen
Authors: Huang Yongfang , Feng Zhengang , Zhang Henglong , Yu Jianying
Published: August 2012

Layered double hydroxide (LDH) modified bitumen was prepared via melt blending. The effects of LDHs on the physical properties and aging properties of bitumen were studied. The influence of LDHs on the chemical structure of bitumen before and after a thin film oven test (TFOT) and an ultraviolet (UV) radiation test was evaluated by means of Fourier transform infrared (FTIR) spectroscopy analysis. The results show that with increasing LDH content, the softening point and viscosity of bitumen gradually increase, whereas the ductility and penetration of bitumen decrease. LDHs can improve the ability of bitumen to resist TFOT aging and UV aging, especially when the LDH content is more than 3 wt. %. In the FTIR analysis, it is seen that LDHs can inhibit the oxidation of bitumen during TFOT and UV aging, resulting in smaller carbonyl and sulphoxide contents than in the pristine bitumen.
Chloride Binding Capacity of Cement Paste Containing Layered Double Hydroxide (LDH)
Authors: Zhonghe Shui , Juntao Ma , Wei Chen , Xiaoxing Chen
Published: August 2012

The chloride binding capacity of concrete can affect the rate of chloride ingress, which ultimately determines the chloride-ion resistance. A layered double hydroxide (LDH) can absorb the chloride ions in cement paste and delay chloride ingress in the structure. A method for evaluating the chloride binding capacity of cement paste was used in the experiment reported herein. We compare Mg-Al LDH under different treatments (including CO32− series and NO3− series) in order to determine the chloride binding capacity of the LDH. The binding mechanism is explored in this article. The experimental results indicate that LDH processes have a remarkable chloride ion binding capacity. The addition of LDH can improve the chloride binding capacity of cement paste significantly. Cement paste containing roasted LDH has a better chloride binding capacity than that containing unroasted LDH or rehydrated LDH. Based on the comparison of LDHs with different anions, the chloride binding capacity of NO3− series LDH appears to be more powerful than that of CO32− series LDH.
Comparison of Tensile Properties of Strain Hardening Cementitious Composite Cured in Normal and Accelerated Conditions
Authors: Qian Shunzhi , Zhang Zhigang
Published: August 2012

Strain hardening cementitious composite (SHCC) has shown increasing field applications recently to take advantage of its unique tensile behavior, yet existing tensile test typically requires 28 days normal curing (NC). While this curing method is acceptable for research purpose in laboratory, it is certainly not practical for rapid quality control purpose of SHCC material onsite. Furthermore, Uniaxial Tensile Test (UTT) commonly used for SHCC material is relatively complicated and sometime difficult to implement. This paper proposes to use tensile and/or bending results from accelerated cured (AC) specimens to predict tensile properties of SHCC material under NC. The tensile test result from AC specimens has been validated with that from NC specimens with reasonable agreement. This makes it possible to use AC tensile test result to predict that from NC condition. Additionally, tensile properties predicted from AC bending specimens via inverse method have been validated with that from NC tensile specimens with certain success. Overall, it is expected that this proposed method can greatly shorten the time required for rapid quality control purpose, contributing to wider application of SHCC material in civil infrastructures.
Using Disturbed State Concept to Predict the Stress–Strain Response of Concrete Attacked by Sulfate
Authors: Nie Yanfeng , Qian Chunxiang
Published: August 2012

The disturbed state concept (DSC) provides a general way for constitutive modeling of deforming materials. This paper presents the experimental and analytical results for the development of methodology for predicting the stress-strain response of concrete attacked by sulfate. Ultrasonic pulse velocity (UPV) is used to identify a function for disturbance (D). The elastoplastic model and simplified hydrostatic stress model are adopted for the definition of the relative intact state (RI) and fully adjusted state (FA), respectively. Thus, the stress–strain curve can be predicted using the DSC model based on nondestructive method. The comparison results show that the proposed constitutive model is satisfied with application in similar condition.
Researching New Religious Movements from the Inside Out and the Outside In
Authors: Gleig Ann
Published: August 2012

Drawing on my own fieldwork experiences with the transnational Integral Yoga community, this essay offers some reflections on two possible approaches to bridging insider-outsider perspectives in the study of new religious movements. First, I consider Gerald Larson's suggestion of a “relationship of mutual reciprocity” between researcher and religious community. Second, I discuss the value of a participatory approach that attempts to integrate engaged participation with critical distance in the study of religion. I use my collaborative experience co-authoring an academic article on Sri Aurobindo and the contemporary yoga scene with an Integral Yoga practitioner to argue that while Larson's reciprocal enterprise risks either sacrificing critical concerns to apologetic agendas, or polarizing the insider as apologetic and the outsider as reductive, a participatory approach proposes a way to put insider-outsider perspectives into a more creative relation.
Everything You Ever Wanted to Know About Saccharomyces cerevisiae Telomeres: Beginning to End
Authors: Wellinger Raymund J , Zakian Virginia A
Published: August 2012

The mechanisms that maintain the stability of chromosome ends have broad impact on genome integrity in all eukaryotes. Budding yeast is a premier organism for telomere studies. Many fundamental concepts of telomere and telomerase function were first established in yeast and then extended to other organisms. We present a comprehensive review of yeast telomere biology that covers capping, replication, recombination, and transcription. We think of it as yeast telomeres—soup to nuts.
Flexible Optical Interconnects via Thiol-ene Two-photon-induced Polymerization
Authors: Kumpfmueller Josef , Stadlmann Klaus , Li Zhiquan , Satzinger Valentin , Stampfl Juergen , Liska Robert
Published: August 2012

Two-photon polymerization (2PP) is an emerging tool in the field of additive manufacturing technologies, which allows for the elegant 3D lithographic production by means of photosensitive resins. One key advantage of 2PP is the achievable feature resolution. A few tens of nanometers are currently the resolution limit for this novel technique. Fields of applications are as diverse as photonics, microfluidics and biomedicine.

A challenging photonics application for 2PP are optical interconnects, where optical elements on printed circuit boards are connected with waveguides. The possibility for real 3D structuring allows for easier positioning of the cured structures and straightforward processing outperforming techniques such as 2D lithography or reactive ion etching in this regard. If mechanical flexibility of the printed circuit board is required as a property for certain niche applications, polysiloxanes are an interesting class of matrix material. This is also due to their low optical damping behavior and high temperature stability as the material has to withstand temperatures around 250°C during the manufacturing process. In this work, we present our latest approach to create polysiloxane-based waveguides via 2PP of specially tailored thiol-ene formulations. Latest improvements on the ease of processing and the local refractive index increase are shown as well as the proof of principle for waveguiding. Optical waveguides were successfully created via 2PP with writing speeds around 10 mm/min.
Collagen as a Humidity Sensing Dielectric Material
Authors: Hudspeth Mathew A. , Kaya Tolga
Published: August 2012

The motivating principle behind this research is the development of small, wearable devices that would use humidity and temperature measurements as metrics for health monitoring. If it is to be useful as a health monitoring tool, the device needs to respond quickly and predictably to changes in humidity. Collagen is shown to be a viable humidity sensing material for use in capacitive relative humidity (RH) sensors. As a natural by-product of meat and leather industries, collagen presents itself as an interesting and inexpensive alternative to polyimide dielectric sensing materials. We used gelatin, a partially hydrolyzed form of collagen, to allow for easier spin coating. We have successfully fabricated devices by depositing a collagen thin film (1.2 μm) via spin coating, followed by Au/Pd electrodes (60 nm) via sputter coating. A plastic mask made from a rapid prototyping machine was used during physical vapor deposition (PVD) to pattern electrodes. This simple method eliminates the need for the use of more complicated photolithography processes. Interdigitated electrodes (rather than parallel plate electrodes) form a 6 mm wide, planar capacitor structure that has little dependence on dielectric thickness and is not affected by dielectric swelling. Initial findings indicate that these devices very closely match the results of the commercial relative humidity sensor used for reference. The capacitance-humidity relationship is shown to be non-linear, with an average change of 3 fF for every 1% change in RH around 60% RH, and an average change of 7 fF for every 1% change in RH around 80% RH. In this work, we present the fabrication and characterization of these novel collagen-based relative humidity sensors.
Integrating social well being into assessments of water policy: meeting the challenge for decision makers
Authors: Syme Geoffrey J. , Porter Natasha B. , Goeft Ute , Kington Elizabeth A.
Published: August 2012

There is growing concern that sustainable natural resources management is not being achieved because of the lack of integration of social analysis in decision making. Following the economic philosophy of analysis of the value of water at the catchment scale adopted by Hoekstra, Savenije and Chapagain (2001, Integrated Assessment, 2, 199–208), in this paper we discuss the relationship between economic and social factors. It is concluded that a large degree of natural integration between social and economic factors exists, but that there are also some social variables that require separate consideration. The social context of water in catchment management and the range of social variables that need consideration in any adequate analysis are defined. We identify a need for a metric that can include commensurate judgements of social, economic and environmental benefits on a single scale and identifies the challenges that this scale will need to meet. Finally, it is suggested that the simplest way to include social variables in decision making is the employment of psychometric techniques that can measure subjective well being and preferably the relationship between its components. The major obstacle to incorporating such data in decision making will be the need for a cultural change in accepting that subjective measures can play a major role in policy evaluation.
A GIS-based methodology for selecting stormwater disconnection opportunities
Authors: Moore S. L. , Stovin V. R. , Wall M. , Ashley R. M.
Published: August 2012

The purpose of this paper is to introduce a geographic information system (GIS)-based decision support tool that assists the user to select not only areas where (retrofit) sustainable drainage systems (SuDS) could be implemented within a large catchment (>100 ha), but also to allow discrimination between suitable SuDS techniques based on their likely feasibility and effectiveness. The tool is applied to a case study catchment within London, UK, with the aim of increasing receiving water quality by reducing combined sewer overflow (CSO) spill frequency and volume. The key benefit of the tool presented is to allow rapid assessment of the retrofit SuDS potential of large catchments. It is not intended to replace detailed site investigations, but may help to direct attention to sites that have the greatest potential for retrofit SuDS implementation. Preliminary InfoWorks CS modelling of ‘global disconnections’ within the case study catchment, e.g. the removal of 50% of the total impervious area, showed that CSO spill volume could be reduced by 55 to 78% during a typical year. Using the disconnection hierarchy developed by the authors, the feasibility of retrofit SuDS deployment within the case study catchment is assessed, and the implications discussed.
Effect of organic load and nutrient ratio on the operation stability of the moving bed bioreactor for kraft mill wastewater treatment and the incidence of polyhydroxyalkanoate biosynthesis
Authors: Pozo G. , Villamar C. A. , Martínez M. , Vidal G.
Published: August 2012

This paper studies the effect of organic load rate (OLR) and nutrient ratio on operation stability of the moving bed bioreactor (MBBR) for kraft mill wastewater treatment, analyzing the incidence of polyhydroxyalkanoate (PHA) production. The MBBR operating strategy was to increase OLR from 0.25 ± 0.05 to 2.41 ± 0.19 kg COD m−3 d−1 between phases I and IV. The BOD5:N:P ratio (100:5:1 and 100:1:0.2) was evaluated as an operation strategy for phases IV to V. A stable MBBR operation was found when the OLR was increased during 225 days in five phases. The maximum absolute fluorescence against the proportion of cells accumulating PHA was obtained for an OLR of 2.41 ± 0.19 kg COD m−3d−1 and a BOD5:N:P relationship of 100:1:0.2. The increase of PHA biosynthesis is due to the increased OLR and is not attributable to the increased cell concentration, which is maintained constant in stationary status during bioreactor biosynthesis.
Process performance of dry, batch anaerobic digestion of sewage sludge: methanogenic seed mixtures
Authors: Szűcs B. Rózsáné , Szántó G. L. , Simon M. , Füleky Gy.
Published: August 2012

A dry, batch anaerobic digestion (DBAD) process was tested on two sewage sludge types with different methanogenic seed fractions under laboratory conditions. The aim was to indicate optimal sludge:seed mixing ratios and analyse process performance based on degradation rate and reactor-specific methane production. The attained results were compared with the performance of a liquid-state, laboratory-scale stirred reactor (SR). A mixing ratio of at least 1:1.25 (sludge:seed) yielded processes free from significant inhibitions. Further seeding increments resulted in slightly better performances, but much lower sludge fractions treated in the reactors. Compared with the SR process, the DBAD reactors produced comparable degradation rates albeit in a significantly longer process and with somewhat lower reactor-specific methane production rates. These findings indicate that the DBAD method may provide a viable alternative to liquid-state processes if sludge drying is already applied and reactor volume requirements are of importance.
The Effect of Walking on Postprandial Glycemic Excursion in Patients With Type 1 Diabetes and Healthy People
Authors: Manohar Chinmay , Levine James A. , Nandy Debashis K. , Saad Ahmed , Dalla Man Chiara , McCrady-Spitzer Shelly K. , Basu Rita , Cobelli Claudio , Carter Rickey E. , Basu Ananda , Kudva Yogish C.
Published: August 2012

OBJECTIVE

Physical activity (PA), even at low intensity, promotes health and improves hyperglycemia. However, the effect of low-intensity PA captured with accelerometery on glucose variability in healthy individuals and patients with type 1 diabetes has not been examined. Quantifying the effects of PA on glycemic variability would improve artificial endocrine pancreas (AEP) algorithms.

RESEARCH DESIGN AND METHODS

We studied 12 healthy control subjects (five males, 37.7 ± 13.7 years of age) and 12 patients with type 1 diabetes (five males, 37.4 ± 14.2 years of age) for 88 h. Participants performed PA approximating a threefold increase over their basal metabolic rate. PA was captured using a PA-monitoring system, and interstitial fluid glucose concentrations were captured with continuous glucose monitors. In random order, one meal per day was followed by inactivity, and the other meals were followed by walking. Glucose and PA data for a total of 216 meals were analyzed from 30 min prior to meal ingestion to 270 min postmeal.

RESULTS

In healthy subjects, the incremental glucose area under the curve was 4.5 mmol/L/270 min for meals followed by walking, whereas it was 9.6 mmol/L/270 min (P = 0.022) for meals followed by inactivity. The corresponding glucose excursions for those with type 1 diabetes were 7.5 mmol/L/270 min and 18.4 mmol/L/270 min, respectively (P < 0.001).

CONCLUSIONS

Walking significantly impacts postprandial glucose excursions in healthy populations and in those with type 1 diabetes. AEP algorithms incorporating PA may enhance tight glycemic control end points.
Experimental and Quasi-Experimental Studies of Inquiry-Based Science Teaching
Authors: Furtak Erin Marie , Seidel Tina , Iverson Heidi , Briggs Derek C.
Published: August 2012

Although previous meta-analyses have indicated a connection between inquiry-based teaching and improved student learning, the type of instruction characterized as inquiry based has varied greatly, and few have focused on the extent to which activities are led by the teacher or student. This meta-analysis introduces a framework for inquiry-based teaching that distinguishes between cognitive features of the activity and degree of guidance given to students. This framework is used to code 37 experimental and quasi-experimental studies published between 1996 and 2006, a decade during which inquiry was the main focus of science education reform. The overall mean effect size is .50. Studies that contrasted epistemic activities or the combination of procedural, epistemic, and social activities had the highest mean effect sizes. Furthermore, studies involving teacher-led activities had mean effect sizes about .40 larger than those with student-led conditions. The importance of establishing the validity of the treatment construct in meta-analyses is also discussed.
Synthesis of Paeonol Derivatives Linked with 1,2,3-Triazole Moiety by 1,3-Dipolar Huisgen-Cylcoaddition Reaction
Authors: Jiang Yuqin , Shi Xin , Xu Guiqing , Li Wei
Published: August 2012

Paeonol is a major phenolic component isolated from Moutan Cortex, a traditional Chinese medicine. An efficient synthesis of paeonol derivatives linked to a 1,2,3-triazole moiety using a 1,3-dipolar Huisgen-cycloaddition reaction is described. The paeonol derivatives are regioselectively obtained in good yields under mild conditions using Cu(OAc)2·H2O/sodium ascorbate as a catalyst system, and t-BuOH/H2O (1:1, v/v) as a co-solvent.
Efficient Synthesis of the Odourant, 2-Nonen-4-Olide
Authors: Dai Yi-feng , Tian Hong-yu , Sun Bao-guo , Sun Yu-mei , Chen Hai-tao , Liu Xiao-yu
Published: August 2012

A three-step synthesis of 2-nonen-4-olide starting from heptanal is reported. (E)-3-Nonenoic acid, prepared by Knoevenagel condensation of malonic acid and heptanal, was oxidised by performic acid, a process accompanied by lactonisation, to give 3-hydroxynonan-4-olide in 85% yield. This lactone when reacted with MsCl in the presence of Et3N gave, by elimination, 2-nonen-4-olide in 88% yield. The overall yield was 75%. The odour of the product was evaluated by GC-olfactory analysis and sniffing blotter confirming an oily, coconut-like, and rancid odour.
Three-Component Reaction between Trivalent Phosphorus Nucleophiles, Dialkyl Acetylenedicarboxylates and (2,4-Dinitrophenyl) Acetic Acid
Authors: Hassanabadi Alireza , Mosslemin Mohammad H. , Abyar Elaheh , Taleb-Malamiri Mohammad
Published: August 2012

A three-component reaction between dialkyl acetylenedicarboxylates (DAADs) and phosphites in the presence of (2,4-dinitrophenyl)acetic acid leads to dialkyl 2-(dialkoxyphosphoryl)-3-[3-acetyl-2-(2,4-dinitrophenyl)-4-oxosucci-nates in excellent yields. A similar reaction with triphenylphosphine, instead of phosphites, produces the stabilised phosphoranes in good yields.
Preparation and Electrical Properties of Insulation Paper Composed of SiO2 Hollow Spheres
Authors: Liao Ruijin , Zhang Fuzhou , Yuan Yuan , Yang Lijun , Liu Tuan , Tang Chao
Published: August 2012

SiO2 hollow spheres and low relative permittivity insulation paper handsheets composed of these SiO2 hollow spheres with different weight percentages were successfully prepared. Low-content SiO2 hollow spheres were uniformly dispersed in the insulation paper handsheets. The relative permittivity of the immersed oil Kraft-SiO2 hollow sphere handsheets (K-SiO2) initially decreased and then increased with increased amount of SiO2 hollow spheres. K-5% SiO2 possessed the lowest relative permittivity of approximately 1.68 at 50 Hz. The breakdown voltage of the paper-oil-paper composite insulation system increased from 26.4 kV to 30.5 kV with decreased relative permittivity of the paper from 2.55 to 1.68. The relationship between the relative permittivity and electric field strength of typical samples were also calculated.
Green Synthesis of Silver Nanoparticles through Reduction with Solanum xanthocarpum L. Berry Extract: Characterization, Antimicrobial and Urease Inhibitory Activities against Helicobacter pylori
Authors: Amin Muhammad , Anwar Farooq , Janjua Muhammad Ramzan Saeed Ashraf , Iqbal Muhammad Awais , Rashid Umer
Published: August 2012

A green synthesis route for the production of silver nanoparticles using methanol extract from Solanum xanthocarpum berry (SXE) is reported in the present investigation. Silver nanoparticles (AgNps), having a surface plasmon resonance (SPR) band centered at 406 nm, were synthesized by reacting SXE (as capping as well as reducing agent) with AgNO3 during a 25 min process at 45 °C. The synthesized AgNps were characterized using UV–Visible spectrophotometry, powdered X-ray diffraction, and transmission electron microscopy (TEM). The results showed that the time of reaction, temperature and volume ratio of SXE to AgNO3 could accelerate the reduction rate of Ag+ and affect the AgNps size and shape. The nanoparticles were found to be about 10 nm in size, mono-dispersed in nature, and spherical in shape. In vitro anti-Helicobacter pylori activity of synthesized AgNps was tested against 34 clinical isolates and two reference strains of Helicobacter pylori by the agar dilution method and compared with AgNO3 and four standard drugs, namely amoxicillin (AMX), clarithromycin (CLA), metronidazole (MNZ) and tetracycline (TET), being used in anti-H. pylori therapy. Typical AgNps sample (S1) effectively inhibited the growth of H. pylori, indicating a stronger anti-H. pylori activity than that of AgNO3 or MNZ, being almost equally potent to TET and less potent than AMX and CLA. AgNps under study were found to be equally efficient against the antibiotic-resistant and antibiotic-susceptible strains of H. pylori. Besides, in the H. pylori urease inhibitory assay, S1 also exhibited a significant inhibition. Lineweaver-Burk plots revealed that the mechanism of inhibition was noncompetitive.
Chemical Composition and in Vitro Evaluation of the Antioxidant and Antimicrobial Activities of Eucalyptus gillii Essential Oil and Extracts
Authors: Ben Hassine Dorsaf , Abderrabba Manef , Yvon Yan , Lebrihi Ahmed , Mathieu Florence , Couderc François , Bouajila Jalloul
Published: August 2012

In this study, essential oil and various extracts (hexane, petroleum ether, acetone, ethanol, methanol and water) of Eucalyptus gilii were screened for their chemical composition, antimicrobial and antioxidant activities. The essential oil chemical composition was analyzed by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame ionization detection (GC-FID), respectively. Thirty four compounds were identified, corresponding to 99.5% of the total essential oil. Tannins [104.9–251.3 g catechin equivalent (CE)/Kg dry mass], flavonoids [3.3–34.3 g quercetin equivalent (QE)/Kg dry mass], phenolics [4.7–216.6 g gallic acid equivalent (GAE)/Kg dry mass] and anthocyannins [1.2–45.3 mg cyanidin-3-glucoside equivalent (C3GE)/Kg dry mass] of various extracts were investigated. Free radical scavenging capacity of all samples was determinedt. In the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, the IC50 of essential oil was 163.5 ± 10.7 mg/L and in the 2,2'-azinobis-3-ethylbenzothiazoline-6-sulphonate (ABTS) assay, it was 94.7 ± 7.1 mg/L. Among the various extracts, the water extract showed the best result (IC50 = 11.4 ± 0.6 mg/L) in the DPPH assay which was comparable to vitamin C (IC50 = 4.4 ± 0.2 mg/L). The antimicrobial activities were evaluated against different bacterial and fungal strains. Gram positive bacteria were found to be more sensitive to the essential oil and extracts than Gram negative ones. Anthocyanins seem to have a major effect on the growth of Bacillus subtilis (R2 = 0.79). A significant antifungal activity was observed against the yeast and fungi. Correlations between chemical composition and antioxidant activities were studied and R2 values were about 0.96 for the effect of phenolics on the DPPH assay.
Fault Diagnostics for Turbo-Shaft Engine Sensors Based on a Simplified On-Board Model
Authors: Lu Feng , Huang Jinquan , Xing Yaodong
Published: August 2012

Combining a simplified on-board turbo-shaft model with sensor fault diagnostic logic, a model-based sensor fault diagnosis method is proposed. The existing fault diagnosis method for turbo-shaft engine key sensors is mainly based on a double redundancies technique, and this can’t be satisfied in some occasions as lack of judgment. The simplified on-board model provides the analytical third channel against which the dual channel measurements are compared, while the hardware redundancy will increase the structure complexity and weight. The simplified turbo-shaft model contains the gas generator model and the power turbine model with loads, this is built up via dynamic parameters method. Sensor fault detection, diagnosis (FDD) logic is designed, and two types of sensor failures, such as the step faults and the drift faults, are simulated. When the discrepancy among the triplex channels exceeds a tolerance level, the fault diagnosis logic determines the cause of the difference. Through this approach, the sensor fault diagnosis system achieves the objectives of anomaly detection, sensor fault diagnosis and redundancy recovery. Finally, experiments on this method are carried out on a turbo-shaft engine, and two types of faults under different channel combinations are presented. The experimental results show that the proposed method for sensor fault diagnostics is efficient.
Closed Loop Control of Penetration Depth during CO2 Laser Lap Welding Processes
Authors: Sibillano Teresa , Rizzi Domenico , Mezzapesa Francesco P. , Lugarà Pietro Mario , Konuk Ali Riza , Aarts Ronald , Veld Bert Huis in ’t , Ancona Antonio
Published: August 2012

In this paper we describe a novel spectroscopic closed loop control system capable of stabilizing the penetration depth during laser welding processes by controlling the laser power. Our novel approach is to analyze the optical emission from the laser generated plasma plume above the keyhole, to calculate its electron temperature as a process-monitoring signal. Laser power has been controlled by using a quantitative relationship between the penetration depth and the plasma electron temperature. The sensor is able to correlate in real time the difference between the measured electron temperature and its reference value for the requested penetration depth. Accordingly the closed loop system adjusts the power, thus maintaining the penetration depth.
Design and Fabrication of a Large-Stroke Deformable Mirror Using a Gear-Shape Ionic-Conductive Polymer Metal Composite
Authors: Wei Hsiang-Chun , Su Guo-Dung John
Published: August 2012

Conventional camera modules with image sensors manipulate the focus or zoom by moving lenses. Although motors, such as voice-coil motors, can move the lens sets precisely, large volume, high power consumption, and long moving time are critical issues for motor-type camera modules. A deformable mirror (DM) provides a good opportunity to improve these issues. The DM is a reflective type optical component which can alter the optical power to focus the lights on the two dimensional optical image sensors. It can make the camera system operate rapidly. Ionic polymer metal composite (IPMC) is a promising electro-actuated polymer material that can be used in micromachining devices because of its large deformation with low actuation voltage. We developed a convenient simulation model based on Young’s modulus and Poisson’s ratio. We divided an ion exchange polymer, also known as Nafion®, into two virtual layers in the simulation model: one was expansive and the other was contractive, caused by opposite constant surface forces on each surface of the elements. Therefore, the deformation for different IPMC shapes can be described more easily. A standard experiment of voltage vs. tip displacement was used to verify the proposed modeling. Finally, a gear shaped IPMC actuator was designed and tested. Optical power of the IPMC deformable mirror is experimentally demonstrated to be 17 diopters with two volts. The needed voltage was about two orders lower than conventional silicon deformable mirrors and about one order lower than the liquid lens.
Que nous apprennent les BRIC ? Trois conjectures sur les économies émergentes
Authors: Vercueil Julien
Published: August 2012

L’article part d’une définition exploratoire de la notion « d’économie émergente » pour s’intéresser aux quatre plus éminentes : le Brésil, la Russie, l’Inde et la Chine. Il formule trois conjectures à propos de ces économies, illustrées par les BRIC, malgré leurs différences : la cohérence institutionnelle est un préalable à l’émergence économique ; les trajectoires des BRIC ont été pilotées en temps réel ; il n’existe pas de voie optimale unique ( one best way ) de l’émergence économique.
La Banque mondiale et la genèse de la notion de bonne gouvernance
Authors: Diarra Gaoussou , Plane Patrick
Published: August 2012

On propose une analyse du paradigme de la bonne gouvernance en s’intéressant aux différentes évolutions dans les dimensions économiques, politiques et sociales. L’analyse est structurée autour de la Banque mondiale qui a été l’un des promoteurs du paradigme de la gouvernance. Les stratégies utilisées par l’organisation pour promouvoir la bonne gouvernance sont analysées à travers son pouvoir de persuasions et d’injonctions qui emprunte les canaux de la production et de diffusion du savoir, les incitations et les conditionnalités financières dans le cadre des politiques d’aide au développement. Elles sont également étudiées à l’aune de leurs influences directes et indirectes sur le comportement des pays et organismes partenaires, bilatéraux et multilatéraux.
L'impact de la microfinance : un enjeu politique au prisme de ses controverses scientifiques
Authors: Bédécarrats Florent
Published: August 2012

L’idée s’est répandue que les évaluations d’impact rigoureuses seraient une nouveauté et que l’on viendrait de découvrir que la microfinance n’est pas la solution miracle contre la pauvreté. Cependant, l'analyse d'un corpus de 154 études montre qu’il s’agit d’une question ancienne qui n'a jamais été consensuelle. Cette analyse révèle l'essor que connaissent actuellement les approche évaluation quantitatives et académiques, au détriment d'approches plus opérationnelles.
Cutting Edge: Generation of Memory Precursors and Functional Memory CD8+ T Cells Depends on T Cell Factor-1 and Lymphoid Enhancer-Binding Factor-1
Authors: Zhou Xinyuan , Xue Hai-Hui
Published: August 2012

T cell factor (TCF)-1 and lymphoid enhancer-binding factor (LEF)-1 transcription factors have redundant roles in promoting thymocyte maturation. TCF-1 has been recently shown to critically regulate memory CD8+ T cell differentiation and persistence. The complete spectra of regulatory roles for TCF-1 and LEF-1 in CD8+ T cell responses are yet unknown. We conditionally targeted LEF-1, and by combination with germline deletion of TCF-1, we found that loss of both factors completely abrogated the generation of KLR G1loIL-7Rα+ memory precursors in effector CD8+ T cell populations in response to Listeria monocytogenes infection. Whereas CD8+ effectors deficient for TCF-1 and LEF-1 retained the capacity to express IFN-γ, granzyme B, and perforin, they were defective in TNF-α production. In the memory phase, the Ag-specific CD8+ T cells lacking TCF-1 and LEF-1 exhibited an effector phenotype and were severely impaired in secondary expansion upon rechallenge. Thus, TCF-1 and LEF-1 cooperatively regulate generation of memory precursors and protective memory CD8+ T cells.
Construção de linguagens documentárias em sistemas de recuperação da informação: a importância da garantia do usuário
Authors: Oliveira Dalgiza Andrade , Araujo Ronaldo Ferreira de
Published: August 2012

O artigo tem a pretensão de discutir a importância da garantia do usuário no processo de planejamento e elaboração de linguagens documentárias. Assim, o trabalho de cotejamento foi realizado por meio de revisão de literatura de estudos de autores que abordam tal temática, dentro do escopo do processo classificatório, encontrado na Biblioteconomia e na Ciência da Informação. O artigo, embora concentre sua atenção na garantia do usuário, conceitua sinteticamente a garantia literária, a garantia estrutural e a garantia cultural. Discorre-se conceitualmente acerca dos Sistemas de Recuperação de Informação e dos Sistemas de Informação, das linguagens documentárias e das representações documentárias utilizadas no processo de organização da informação. Dentre as linguagens documentárias com ênfase na representação da informação, é destacado, especificamente, o tesauro enfocando as suas principais características no que se refere à validação de termos. Aborda os mecanismos de indexação e descrição dos documentos. Discute-se sobre os tesauros na sua importante relação com a garantia do usuário.
Política de desenvolvimento de coleções para documentos eletrônicos: tendências nacionais e internacionais
Authors: Dias Geneviane Duarte , Silva Terezinha Elisabeth da , Cervantes Brígida Maria Nogueira
Published: August 2012

Apresenta os conceitos e as características da política de desenvolvimento de coleções. Em seguida, explora as definições e as peculiaridades que constituem um documento eletrônico, bem como, suas vantagens e aplicações. Revela como as bibliotecas universitárias nacionais e internacionais estão trabalhando com a política de desenvolvimento de coleções para documentos eletrônicos, identificando um crescimento relevante e a expansão das políticas referentes aos documentos eletrônicos, ainda em evolução.
On the chemical nature of the oxygenated organic aerosol: implication in the formation and aging of α-pinene SOA in a Mediterranean environment, Marseille
Authors: El Haddad I. , D'Anna B. , Temime-Roussel B. , Nicolas M. , Boreave A. , Favez O. , Voisin D. , Sciare J. , George C. , Jaffrezo J.-L. , Wortham H. , Marchand N.
Published: August 2012

Abstract. Organic Aerosol (OA) measurements were conducted during summer 2008 at an urban background site, in Marseille, France's second city and the largest port in the Mediterranean, an urban industrialized environment known for its active photochemistry. PM2.5 was collected using high volume samplers and analyzed for elemental and organic carbon, major ions (NH4+, NO3− and SO42−), humic-like-substances, organic markers (i.e. primary tracers and α-pinene oxidation products), elemental composition and radiocarbon content (14C). The real-time chemical characterization of submicron particles was also achieved using a compact time of flight aerosol mass spectrometer. Positive matrix factorization conducted on the organic aerosol mass spectra matrix revealed four factors, including traffic emissions (hydrocarbon-like OA, HOA), industrial emissions, semi-volatile (SV-OOA) and low-volatile (LV-OOA) oxygenated organic aerosol (OOA) related to oxidation processes. The results obtained were in excellent agreement with chemical mass balance source apportionments conducted in conjunction with organic markers and elements. It appears that while primary emissions contributed only 22% to the total OA (of which 23% was associated with industrial processes), OOA constituted the overwhelming fraction. Radiocarbon measurements suggest that about 80% of this fraction was of non-fossil origin, assigned predominantly to biogenic secondary organic aerosol. Non-fossil carbon appears to especially dominate the LV-OOA fraction, an aged long-range-transported OOA, marginally affected by local anthropogenic SOA. We also examined the relation between OOA and α-pinene SOA obtained based on the levels of α-pinene oxidation products. α-pinene SOA showed good correlation with SV-OOA, suggesting that the compounds used for estimating α-pinene SOA appear to pertain mainly to the moderately oxidized fraction. In contrast, LV-OOA was found to be intimately related to HUmic LIke substances (HULIS), meaning that these two fractions arise from the same oxidation pathways and share a similar chemical composition (i.e. poly-carboxylic species). A thorough analysis of α-pinene individual oxidation products showed that aging can heavily impact their respective concentrations, as early generation products seem to decay with photochemistry when more oxidized compounds seem to be formed.
Dynamical characteristics of ice supersaturated regions
Authors: Gierens K. , Brinkop S.
Published: August 2012

Abstract. The typical distributions of dynamical fields within ice supersaturated regions are investigated. The dynamical fields divergence, relative vorticity, and vertical velocity are analysed statistically in two ways, namely using the unconditioned data and data conditioned on the presence of ice supersaturation. Two geographical regions are considered, namely Europe (250 hPa level) and the tropical belt from 30° S to 30° N on two pressure levels (200 and 150 hPa). The study is based on forecast data from the European Centre for Medium-Range Weather Forecasts for March 2012 solely. We find that histograms (frequency distributions) and low order moments of the dynamical fields differ substantially and statistically significantly inside and outside of ice supersaturated regions. As expected, upward and divergent flow favours ice supersaturation. But we find also that ice supersaturation is mostly located in anti-cyclonic flow. The latter result is probably due to the structure of warm/moist and cold/dry air streams in synoptic disturbances in mid-latitudes, but probably merely coincidental in the tropical belt.