Effect of compaction pressure on consolidation behaviour of unsaturated silty soil

The effect of compaction pressure on subsequent soil behaviour during isotropic consolidation has been investigated by conducting controlled-suction triaxial tests on samples of an unsaturated compacted silty soil. A comprehensive set of laboratory experiments was carried out in a double-walled triaxial apparatus on samples of unsaturated soil that were prepared using two different compaction pressures. The axis translation technique was used for creating the desired suctions in the samples. In the experiments, the soil samples were subjected to isotropic consolidation under constant suctions. The results show that different compaction pressures produce different fabrics in a soil and therefore affect the behaviour of the soil. The results also show that the value of yield stress and the location of the loading¿collapse (LC) yield curve are functions of soil fabric. Furthermore, it is shown that the slopes of normal consolidation lines for densely and loosely compacted samples differ in unsaturated conditions but are the same in saturated soils. A comparison is made between the behaviour of the dense and loose samples, and the difference in the behaviour is explained

The state of Play with iPSCs and Spinal Cord Injury

The application of induced pluripotent stem cell (iPSC) technologies in cell based strategies, for the repair of the central nervous system (with particular focus on the spinal cord), is moving towards the potential use of clinical grade donor cells. The ability of iPSCs to generate donor neuronal, glial and astrocytic phenotypes for transplantation is highlighted here, and we review recent research using iPSCs in attempts to treat spinal cord injury in various animal models. Also discussed are issues relating to the production of clinical grade iPSCs, recent advances in transdifferentiation protocols for iPSC-derived donor cell populations, concerns about tumourogenicity, and whether iPSC technologies offer any advantages over previous donor cell candidates or tissues already in use as therapeutic tools in experimental spinal cord injury studies

Optimization of superstructured fiber bragg gratings for microwave photonic filters response

The microwave photonic responses of superstructured fiber Bragg gratings in combination with dispersive fiber are investigated theoretically and experimentally. The superstructured gratings are optimized, taking account of the spectral response of the broad-band source, Erbium-doped fiber amplifier, and optical tunable filter to achieve a filter response with sidelobe suppression of more than 60 dB. © 2004 IEEE

Assessment of Physicochemical and Fatty Acids Composition of Crude Seed Oil Extract of Azadirachta indica Adr. Juss. for its potential in Biodiesel Production

This study investigates the physico-chemical and fatty acids composition of crude seed oil extracts of Azadirachta indica . The main objective was to evaluate some biodiesel characteristics of the crude seed oil extract of Azadirachta indica. The procedures of the Association of Official and Analytical Chemist (AOAC) were used for assessment of some physical, biochemical, and fatty acids constituents of the test seed oil extract. The physical properties assayed for indicate that the oil is liquid at room temperature, non-drying, with specific gravity, with flash and melting points of 0.910±0.08 g/cm3, 80±2.10°C and 76±1.60°C respectively. The chemical properties included 66.77±2.55 g/100g (iodine value), 1.465±0.07 (refractive index@ 30°C), 212.96±1.16 mgKOH/g (saponification value), 0.39±0.16 meq/Kg (peroxide value), 4.24±0.12 mgKOH/g (acid value), 2.20±0.12 mm2/s (viscosity value), 56.91±2.19 (cetane number), 39.21±1.11 MJ/kg (calorific value) and 2.13±0.05% w/w (free fatty acids). Fatty acids composition of the crude seed oil of A. indica obtained were linoleic, hexadecanoic, octadecanoic and alpha linolenic acids, with retention time and % composition of 18.2 min and 10.8±0.50%, 22.2 min and 30.01±1.79%, 18.2 min and 59.10±2.22%, and 20.2 min and 0.09±0.02% respectively. The crude seed oil extract clearly presents a potential as a biodiesel substrate for incorporation as a proximate blend in auto-engines. This therefore would necessitate intensive afforestation efforts of the plant species for sustainable utilization. Keywords: Azadirachta indica, Biodiesel, physico-chemical, fatty acids, crude seed oil, extract

Direct real-time cavity mode assessment and optimization technique for fiber lasers

A simple technique for direct real-time assessment of a fiber laser cavity-mode condition during operation is demonstrated. Mode stabilization and optimization with this cavity-mode monitoring and conditioning feedback scheme shows significant improvements to the output performance

A stress–temperature superposition approach to study the nonlinear resilient behavior of cold recycled mixtures (CRM) with active filler addition

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract:] The asphalt paving sector is currently embracing and enhancing cold mixture technologies to reduce carbon emissions and decarbonize its operations. Cold recycled mixtures (CRM) have proven to be a promising alternative in road construction and rehabilitation, becoming a primary research focus. This study evaluates the effects on compactability and volumetric properties of adding 1% Portland cement or 1% hydrated lime to CRM made with 100% reclaimed asphalt pavement and bitumen emulsion. Dynamic triaxial tests with different confinement pressures (ranging from 20 to 200 kPa) and temperatures (5, 15, 25, and 35 °C) were used to determine the influence of these active filler additions on the resilient modulus (Mr) of the mixtures. All the mixtures exhibited increased Mr values at lower temperatures and reduced stress–dependency. Cement addition had the most favorable effect on compactability, reducing the necessary compaction energy, while mixtures with hydrated lime had more substantial increases in Mr and reduced stress dependencies. Finally, the results were analyzed by plotting master curves using a proposed novel approach called Stress–Temperature Superposition Principle (STSP), which allows for simpler and more straightforward analyses.The authors would like to acknowledge funding for the project BIA2016-80317-R from the Spanish Ministry of Science and Innovation, with an associated pre-doctoral scholarship for the training of research workers (FPI) BES-2017-079633. This scholarship also funded the corresponding author for conducting a pre-doctoral stay in a foreign research center, making it possible to carry out this research study. An special acknowledgement to the Universidade da Coruña/ CISUG for funding part of the Elsevier’s open access charge. The authors also acknowledge Milestone Contractors for contributing to the investigation with the recycled materials used. Moreover, finally, the corresponding author would like to express special thanks to Ayesha Shah, Behnam Jahangiri, and Mohammad Ali Notani for their help and support during the laboratory work, and to the rest of the people in the Innovative Materials and Pavements Group, Oscar Moncada, Bongsuk Park, Maya Khajehvand, for their hospitality during the pre-doctoral stay.Ministerio de Economía, Industria y Competitividad; BIA2016-80317-

Mask-less lithography for fabrication of optical waveguides

A flexible method for fabricating shallow optical waveguides by using femtosecond laser writing of patterns on a metal coated glass substrate followed by ion-exchange is described. This overcomes the drawbacks of low index contrast and high induced stress in waveguides directly written using low-repetition rate ultrafast laser systems. When compared to conventional lithography, the technique is simpler and has advantages in terms of flexibility in the types of structures which can be fabricated

A new method for microwave generation and data transmission using DFB laser based on fiber bragg gratings

A novel architecture for microwave/millimeter-wave signal generation and data modulation using a fiber-grating-based distributed feedback laser has been proposed in this letter. For demonstration, a 155.52-Mb/s data stream on a 16.9-GHz subcarrier has been transmitted and recovered successfully. It has been proved that this technology would be of benefit to future microwave data transmission systems. © 2006 IEEE

Understanding selectivity in radio frequency and microwave sorting of porphyry copper ores

Continuous high-throughput microwave treatment followed by infrared thermal imaging (MW-IR) has previously been shown to provide attractive separations for a number of porphyry copper ores, leading to rejection of a large proportion of barren fragments from ore-grade material or concentration of copper values from waste-grade material. However, the efficacy of the sorting process is reduced by the presence of hydrated clays and pyrite. Literature measurements have shown differences in the conductivity of pyrite and copper sulphides such as chalcopyrite at radio frequencies. In this work the potential of using radio frequency (RF) heating to exploit these differences and achieve improved selectivity between copper and iron sulphides, is investigated. For the first time a novel bulk materials handling and presentation method that facilitates even heating of angular ore fragments in parallel plate RF systems is discussed. The fragment-by-fragment thermal response of five ore samples under equivalent pilot MW-IR and RF-IR processing conditions is evaluated, showing that there is an increase in selectivity in the heating of hydrated clay minerals in RF compared to microwave. It is suggested, again for the first time, that selectivity in the microwave processing of ores containing semi-conducting minerals is due predominantly to magnetic absorption (induction heating) caused by eddy currents associated with the magnetic field component of electromagnetic energy. In radio frequency processing, where electric field is the dominant component, heating of semi-conducting minerals is limited by the electric field screening effect. This effect is demonstrated using synthetic fragments. Thermal response profiles of synthetic fragments show that approximately 2.5 times the mass of sulphide minerals to hydrated clay minerals would result in an equal temperature increase for microwave heated fragments in which the microwave-heating minerals are evenly disseminated throughout the matrix. This understanding provides the foundations for development of models incorporating different thermal responses for individual heated phases, alongside other textural and treatment variables, that can be used to predict how close to intrinsic sortability ores will perform in MW-IR and RF-IR without the need for extensive processing trials

Optical autocorrelator that uses a surface-emitting second-harmonic generator on (211)B GaAs

An optical autocorrelator grown on a (211)B GaAs substrate that uses visible surface-emitted second-harmonic generation is demonstrated. The (211)B orientation needs TE mode excitation only, thus eliminating the problem of the beating between the TE and TM modes that is required for (100)-grown devices; it also has the advantage of giving higher upconversion efficiency than (111) growth. Values of waveguide loss and the difference in the effective refractive index between the TE(0) and TE(1) modes were also obtained from the autocorrelation experiment