Small Traces Research Articles

Sulphur tolerance of Au-modified Ni/GDC during catalytic methane steam reforming

Au doping and high calcination temperatures improve the sulphur tolerance of Ni/GDC, a potential SOFC anode.

Improved DNA-Based Identification of Cervidae Species in Forensic Investigations

Abstract The main reasons for wildlife forensic research are animal poaching, illegal trade, and falsified game meat products. Small trace amounts, old and degraded materials present the most common samples in revealing criminal activities in this field. This is the reason why it is crucial to use adequate and reliable methods and samples to identify animal species killed outside the hunting season or species protected by law. In this study, different endpoint PCR and real-time PCR protocols were compared in the identification of three Cervidae species (Capreolus capreolus, Cervus elaphus, Dama dama) from old and damaged material found in an enclosed area where the animals were kept. From a total of 129 samples, end point PCR provided results for 119 samples, while real-time PCR was successful in all cases. Also, we created and tested a protocol for simultaneous analyses of different types of samples, which is of great importance as when the amplification is carried out simultaneously it is more cost efficient and speeds up the process.

Callixylon wendtiisp. nov., a new species of archaeopteridalean progymnosperm from the Late Devonian of Anti-Atlas, Morocco

ABSTRACTArchaeopterid trees were the main components of most Late Devonian forests. Their aerial axes characterised by a eustele with mesarch primary xylem strands, leaf traces departing radially from cauline bundles and secondary xylem tracheids with radial pits arranged in groups, are referred to the genusCallixylonZalessky. The nineteen species ofCallixylondescribed to date from North America, North Africa, Europe, Xinjiang and several parts of Russia range from the late Givetian to the Mississippian. In this paper, we describe a new species ofCallixylonfrom two specimens collected in the Famennian locality of Mader el Mrakib in eastern Anti-Atlas.Callixylon wendtiisp. nov. is characterised by the presence of sclerotic nests in the pith, a new character for the genus. Its wood shows narrow rays of variable height, with unevenly distributed ray tracheids. Small vascular traces crossing the wood within the two innermost growth rings are interpreted as evidence for short-lived leaves. This discovery adds to the diversity of the genusCallixylonin an area of northern Gondwana that may have been favourable to the establishment of a diverse community of archaeopterid trees.

Variation in salt-body interval velocities in the deepwater Gulf of Mexico: Keathley Canyon and Walker Ridge areas

Borehole measurements of salt-body P-wave interval velocities from 55 wells in the vicinity of the Keathley Canyon and Walker Ridge areas of the Gulf of Mexico vary from [Formula: see text] ([Formula: see text]) to [Formula: see text] ([Formula: see text]) with mean velocity of [Formula: see text] ([Formula: see text]) and standard deviation of [Formula: see text] ([Formula: see text]). The velocities vary significantly with latitude. Five different interval velocity zones have been identified with each having specific associated mineralogies within a latitude range. In the midlatitude zones, sylvite, various clastics, and small traces of anhydrite and gypsum are found within the salt, yielding a salt interval velocity variation from 14,388 to [Formula: see text] ([Formula: see text]–[Formula: see text]). The salt interval velocity in the southern limits of the study area is higher than [Formula: see text] ([Formula: see text]) and is associated with more gypsum. The northernmost wells are anhydrite rich and exhibit the highest velocities. The interval velocities are relatively uncorrelated and are insensitive to factors such as wellbore temperature, depth, and overburden pressure. Composite medium modeling of mixed salt-body mineralogies and multiple regression analysis indicate that compositional variation within the salt body can explain the observed velocity variations.

$\gamma $ -Ray Detection Using Commercial Off-the-Shelf CMOS and CCD Image Sensors

In this paper, we present the results of research on the response of four types of commercial off-the-shelf (COTS), CMOS, and charge-coupled device (CCD) image sensors to $\gamma $ photons. The aim of this paper was to study the potential use of CCD and CMOS COTS image sensors as $\gamma $ -ray detectors. A 60Co $\gamma $ source was used to study the response behavior of the sensors to the irradiant photons. The results show that the CMOS image sensors have much less background noise before irradiation and have better radiation resistance below 51.24 Gy. The background noise of CCD sensors obviously increases with a larger total ionizing dose. The linearity of the dose-rate response of CCD COTS sensors is better than that of CMOS COTS sensors. Both mean pixel value and cumulative pixel value may be used to obtain the photon dose rate. The sensor technology structure difference leads to the different shapes of events. The Compton scattering of 60Co $\gamma $ photons in silicon caused the recorded patterns to show not only dots but also small streaks or traces. The peak value provides the photon energy, while the peak shape and radius can be used to classify the particle. CMOS COTS sensors are suitable for the particle classification, while CCD COTS sensors are better for energy resolution.

Hardware Trojan Detection Through Chip-Free Electromagnetic Side-Channel Statistical Analysis

The hardware Trojan (HT) has become a major threat for the integrated circuit (IC) industry and supply chain, and has motivated numerous developments of Trojan detection schemes. Although the side-channel method is the most promising one, nearly all of the side-channel methods require fabricated golden chips, which are very difficult to obtain in reality. In this paper, we propose a novel strategy for HT detection using electromagnetic side-channel-based spectrum modeling and analyzing. We utilize the design data at early stage of the IC lifecycle, and the generated spectrum can serve as the golden reference, and thus we do not need the fabricated golden chips anymore. Another very important feature is that our method is immune to the process variation theoretically. Experimental results on selected Advanced Encryption Standard benchmark circuits on FPGA show that our proposed method can effectively detect Trojans even with very small traces.

Spectral Studies of Nanosecond Laser Interaction with Aluminum-Based Alloy Containing Traces of Magnesium in Air

Parametric study of optical emission Characterization of the plasma-assisted laser ablation of aluminium-based alloy that contains small traces of magnesium is presented. The emission of lines from the plasma of the target in the wavelength range 200-900nm has been carefully investigated at the same experimental conditions. It was found that all the emission intensities of the ionic and neutral magnesium lines are subjected to self-absorption, whereas the aluminium ionic lines were free from self-absorption. The results assure that, in case of the presence of self- absorption effect, the temperature varies from (1.7952 - 1.1433 eV) as the delay time is varied from 0 to 5 μs. Whereas, in the case of repairing against the effect, it varies from (1.3240 - 0.9447 eV) for the same delay time variation. At the same time, according to the McWhirter criterion, the electron density was high enough to establish plasma in local thermodynamic equilibrium.

Evidence of the chemical stability of the garnet-type solid electrolyte Li5La3Ta2O12 towards lithium by a surface science approach

The chemical stability between Li metal and garnet-type solid electrolytes is currently under debate, mainly catalyzed by theoretical studies. Here, we investigate the stability of Li5La3Ta2O12 (LLTaO) towards lithium experimentally. Using a surface science approach, lithium is stepwise evaporated on an LLTaO thin film grown by CO2-laser assisted chemical vapor deposition. By annealing of the LLTaO thin film, the Li2CO3 surface layer can be removed, leaving only small traces of Li2CO3, Li2O2 and Li2O behind. The interface formation of LLTaO towards lithium is then monitored by means of X-ray and ultraviolet photoelectron spectroscopy. Neither reaction products related to decomposition nor structural changes in the matrix of the Ta-based garnet-type solid-electrolyte can be detected, indicating that LLTaO exhibits chemical stability under equilibrium conditions. Furthermore, a model for the energy level alignment at the LLTaO/Li interface is discussed.

Recycled Aggregates from Construction and Demolition Waste in the Production of Concrete Blocks

The construction industry generates large amounts of waste, usually mixed, which can be composed of different origin materials, most of them catalogued as non-hazardous. The European Union targets for this waste for 2020 have been already achieved by the UK, but it is mainly developed in downcycling processes (backfilling) whereas upcycling (such as recycle in new concrete batches) still keeps at a low percentage. The aim of this paper is to explore further in the use of recycled aggregates from construction and demolition waste (CDW) in concrete mixes so as to improve upcycling. A review of most recent research and legislation applied in the UK is developed regarding the production of concrete blocks. As a case study, initial tests were developed with a CDW recycled aggregate sample from a CDW plant in Swansea. Composition by visual inspection and sieving tests of two samples were developed and compared to original aggregates. More than 70% was formed by soil waste from excavation, and the rest was a mix of waste from mortar, concrete, and ceramics with small traces of plaster, glass and organic matter. Two concrete mixes were made with 80% replacement of recycled aggregates and different water/cement ratio. Tests were carried out for slump, absorption, density and compression strength. The results were compared to a reference sample and showed a substantial reduction of quality in both mixes. Despite that, the discussion brings to identify different aspects to solve, such as heterogeneity or composition, and analyze them for the successful use of these recycled aggregates in the production of concrete blocks. The conclusions obtained can help increase upcycling processes ratio with mixed CDW as recycled aggregates in concrete mixes.

Experimental methods for the Palaeolithic dry distillation of birch bark: implications for the origin and development of Neandertal adhesive technology

The destructive distillation of birch bark to produce tar has recently featured in debates about the technological and cognitive abilities of Neandertals and modern humans. The abilities to precisely control fire temperatures and to manipulate adhesive properties are believed to require advanced mental traits. However, the significance given to adhesive technology in these debates has quickly outgrown our understanding of birch bark tar and its manufacture using aceramic techniques. In this paper, we detail three experimental methods of Palaeolithic tar production ranging from simple to complex. We recorded the fuel, time, materials, temperatures, and tar yield for each method and compared them with the tar known from the Palaeolithic. Our results indicate that it is possible to obtain useful amounts of tar by combining materials and technology already in use by Neandertals. A ceramic container is not required, and temperature control need not be as precise as previously thought. However, Neandertals must have been able to recognize certain material properties, such as adhesive tack and viscosity. In this way, they could develop the technology from producing small traces of tar on partially burned bark to techniques capable of manufacturing quantities of tar equal to those found in the Middle Palaeolithic archaeological record.

Inhomogeneous Superconducting Behaviour in hbox {La}_{5}hbox {Ni}_{2}hbox {Si}_{3}

The superconducting phase transition at T_mathrm{c} = 2.3 K was observed for the electrical resistivity rho ({T}) and magnetic susceptibility chi (T) measurements in the ternary compound La_{5}hbox {Ni}_{2}hbox {Si}_{3} that crystallizes in the hexagonal-type structure. Although a single-phase character with the nominal stoichiometry of the synthesized sample was confirmed, a small trace of the La–Ni phase was found, being probably responsible for the superconducting behaviour in the investigated compound. The magnetization loop recorded at {T} = 0.5 K resembles a star-like shape which indicates that the density of the critical current can be strongly suppressed by a magnetic field. The low-T _{rho }(T) and specific heat {C}_mathrm{p}({T}) data in the normal state reveal simple metallic behaviour. No clear evidence of a phase transition to any long- or short-range order was found for C_mathrm{p}(T) measurements in the T-range of 0.4–300 K.

Trace fossils of Ordovician radiolarian chert and siliceous mudstone in Newfoundland, Canada

Ordovician radiolarian chert and siliceous mudstone in Newfoundland are examined to elucidate the development of trace fossils in and on the Early Paleozoic ocean bottom. Chert sedimentation in the Shoal Arm Formation (SAF) is limited to a short interval, but its sedimentation rate is high with few siliciclastic materials. Trace fossils are common in chert in the SAF, but their development is interrupted by frequent anoxic events. The trace fossils are larger than trace fossils in the contemporary chert of other areas. In contrast, trace fossils in the Strong Island Chert (SIC) are moderately-sized to small, with a few sandstone beds interbedded with chert. Those characteristics reflect differences in the sedimentary environments. Rocks of the SIC were deposited in a basinal part of a back-arc basin; whereas, those in the SAF were deposited on a small isolated basin. Red chert or siliceous rocks that underlie grey cherts and siliceous rocks of the SIC and the SAF bear small and simple trace fossils. This is a common feature of “oceanic red rocks.” Radiolarian chert and siliceous rocks in Newfoundland also showed that trace fossils are widespread by the Middle Ordovician in the deep-sea environment. The Great Ordovician Biodiversification Event is confirmed in the radiolarian siliceous rocks there.

Microstructure, Mechanical and Surface Morphological Properties of Al5Ti5Cr Master Alloy as Friction Material Prepared by Stir Die Casting

Metal matrix composite offers outstanding properties for better performance of disc brakes. In the present study, the composite of AlTiCr master alloy was prepared by stir die casting method. The developed material was reinforced with (0–10 wt%) silicon carbide (SiC) and boron carbide (B4C). The effects of SiC reinforcement from 0 to 10 wt% on mechanical, microstructure and surface morphological properties of Al MMC was investigated and compared with B4C reinforcement. Physical properties like density and micro Vickers hardness number show an increasing trend with an increase in the percentage of SiC and B4C reinforcement. Mechanical properties viz. UTS, yield strength and percentage of elongation are improved with increasing the fraction of reinforcement. The surface morphology and phase were identified from scanning electron microscopy (SEM) and X-ray diffraction analysis and the oxidized product formed during the casting was investigated by Fourier transformation infrared spectroscopy. This confirms the presence of crystallization of corundum (α-Al2O3) in small traces as one of the alumina phases, within casting sample. Micro-structural characterization by SEM depicted that the particles tend to be more agglomerated more and more with the percentage of the reinforcement. The AFM results reveal that the surface roughness value shows a decreasing trend with SiC reinforcement while roughness increases with increase the percentage of B4C.

Induced charge effects on electrokinetic entry flow

Electrokinetic flow, due to a nearly plug-like velocity profile, is the preferred mode for transport of fluids (by electroosmosis) and species (by electrophoresis if charged) in microfluidic devices. Thus far there have been numerous studies on electrokinetic flow within a variety of microchannel structures. However, the fluid and species behaviors at the interface of the inlet reservoir (i.e., the well that supplies the fluid and species) and microchannel are still largely unexplored. This work presents a fundamental investigation of the induced charge effects on electrokinetic entry flow due to the polarization of dielectric corners at the inlet reservoir-microchannel junction. We use small tracing particles suspended in a low ionic concentration fluid to visualize the electrokinetic flow pattern in the absence of Joule heating effects. Particles are found to get trapped and concentrated inside a pair of counter-rotating fluid circulations near the corners of the channel entrance. We also develop a depth-averaged numerical model to understand the induced charge on the corner surfaces and simulate the resultant induced charge electroosmosis (ICEO) in the horizontal plane of the microchannel. The particle streaklines predicted from this model are compared with the experimental images of tracing particles, which shows a significantly better agreement than those from a regular two-dimensional model. This study indicates the strong influences of the top/bottom walls on ICEO in shallow microchannels, which have been neglected in previous two-dimensional models.

Streptomyces jeddahensis sp. nov., an oleaginous bacterium isolated from desert soil.

A novel strain, G25T, was isolated from desert soil collected near Jeddah in Saudi Arabia. The strain could accumulate nearly 65 % of its cell dry weight as fatty acids, grow on a broad range of carbon sources and tolerate temperatures of up to 50 °C. With respect to to its 16S rRNA gene sequence, G25T is most closely related to Streptomyces massasporeus DSM 40035T, Streptomyces hawaiiensis DSM 40042T, Streptomyces indiaensis DSM 43803T, Streptomyces luteogriseus DSM 40483T and Streptomyces purpurascens DSM 40310T. Conventional DNA-DNA hybridization (DDH) values ranged from 18.7 to 46.9 % when G25T was compared with these reference strains. Furthermore, digital DDH values between the draft genome sequence of G25T and the genome sequences of other species of the genus Streptomyces were also significantly below the threshold of 70 %. The DNA G+C content of the draft genome sequence, consisting of 8.46 Mbp, was 70.3 %. The prevalent cellular fatty acids of G25T comprised anteiso-C15 : 0, iso-C15 : 0, C16 : 0 and iso-C16 : 0. The predominant menaquinones were MK-9(H6), MK-9(H8) and MK-9(H4). The polar lipids profile contained diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylglycerol and phosphatidylinositol mannosides as well as unidentified phospholipids and phosphoaminolipids. The cell wall contained ll-diaminopimelic acid. Whole-cell sugars were predominantly glucose with small traces of ribose and mannose. The results of the polyphasic approach confirmed that this isolate represents a novel species of the genus Streptomyces, for which the name Streptomyces jeddahensis sp. nov. is proposed. The type strain of this species is G25T (=DSM 101878T =LMG 29545T =NCCB 100603T).

Photocatalysis and luminescence properties of zinc stannate oxides

Abstract In the present study, ZnO/SnO 2 nanocomposites and Zn 2 SnO 4 powder phosphors were synthesized via a sol–gel method through the control of annealing process. The coupled oxides ZnO/SnO 2 nanopowders formed after annealing at 400–600 °C, and the spinel zinc stannate phase appeared at 700 °C. On annealing in the temperature range of 1000–1200 °C, Zn 2 SnO 4 is the dominant phase with small traces of ZnO and SnO 2 . The photocatalysis evaluation indicated that the photocatalytic activity of ZnO/SnO 2 nanocomposites for the degradation of azo dye Acid Orange 7 (AO7) was much higher than those of pure ZnO and SnO 2 under near UV light irradiation. The higher photocatalytic activity is related to the formation of nano-heterostructures, which provided an effective way to suppress the charge recombination and enhanced the degradation efficiency consequently. Under excitation at 327 nm, photoluminescence (PL) spectra revealed the Zn 2 SnO 4 powder phosphors having a weak n-UV emission and a broad visible emission around 400–700 nm with peaking at 548 nm. Chromaticity diagram exhibited the Zn 2 SnO 4 powders having the characteristics of near white light emission. The results show that ZnO/SnO 2 nanocomposites and Zn 2 SnO 4 powders have potential applications for the nanophotocatalysts, display, and solid-state lighting devices, respectively.

Microstructure evolution and EBSD analysis of a graded steel fabricated by laser additive manufacturing

This paper demonstrates the successful fabrication of a graded steel with successive 15 layers by direct laser metal deposition. The phase evolution, microstructure and grain growth of the as-built graded steel were investigated by X-ray diffraction (XRD), optical microscopy (OM), and electron back-scatter diffraction (EBSD), respectively. Experimental results showed that the crystal structures of the graded steel evolved from FCC (Austenite) in the first two grades to BCC (Ferrite) with a small trace of Austenite phase. Columnar dendrites are observed in the first and second grade with the growth orientation horizontal to the direction of the laser deposition. The third grade has a finer microstructure with equiaxed grains. Preferred texture was dominant in the microstructure for the first two grades with low-angle grain boundaries (about 2°). No preferred texture was observed in the third grade. Large-angle grain boundaries are available in the third grade with distribution from 50° to 60°. Our findings suggest that a graded steel with microstructure and grain growth orientation evolution can be obtained by direct laser metal deposition. The evolution of microstructure and grain growth was not changed by different scanning rate.

Detecting impact traces on a composite pressure vessel with aluminum-coating optical fiber using a phase-modulated BOCDA sensor

Impact traces on a composite pressure vessel were detected by measuring residual strain in aluminum (Al)-coating optical fiber for the first time. The residual strain was obtained by a Brillouin optical correlation domain analysis (BOCDA) sensor system, where a continuous optical signal was simultaneously phase-modulated to choose the sensing position, and single-side-band modulated to find the Brillouin frequency. This sensor system successfully measured the Brillouin frequency, which can be converted to the strain, along a 500 m long optical fiber, with distance resolution of less than 1.5 cm. The cantilever beam test using a bonded optical fiber presented the strain conversion coefficient, which was determined by the comparison between the measured Brillouin frequency and the strain of an electric strain gauge. Al-coating optical fiber was attached around the surface of a composite pressure vessel, and consecutive impacts at six separate positions were applied using hemisphere and wedge impactors with energies of 10, 20, and 40 J. The measured Brillouin frequencies were the unchanged intrinsic frequency along the whole fiber length, except for the six peak positions, which exactly coincided with the impact positions. The fine measurement at these peak positions showed the frequency peaks to be composed of two split peaks, which were compared with photographs taken while the impacted surfaces were deformed. This confirmed that a dent temporarily formed at an impact position caused the optical fiber to bend twice, and the strain remained at two adjacent positions. Hydraulic pressure test of the composite pressure vessel after the impacts showed that this measurement system could detect small impact traces that do not cause critical structural degradation, as well as large impact damages.

A simplified fractional order impedance model and parameter identification method for lithium-ion batteries.

Identification of internal parameters of lithium-ion batteries is a useful tool to evaluate battery performance, and requires an effective model and algorithm. Based on the least square genetic algorithm, a simplified fractional order impedance model for lithium-ion batteries and the corresponding parameter identification method were developed. The simplified model was derived from the analysis of the electrochemical impedance spectroscopy data and the transient response of lithium-ion batteries with different states of charge. In order to identify the parameters of the model, an equivalent tracking system was established, and the method of least square genetic algorithm was applied using the time-domain test data. Experiments and computer simulations were carried out to verify the effectiveness and accuracy of the proposed model and parameter identification method. Compared with a second-order resistance-capacitance (2-RC) model and recursive least squares method, small tracing voltage fluctuations were observed. The maximum battery voltage tracing error for the proposed model and parameter identification method is within 0.5%; this demonstrates the good performance of the model and the efficiency of the least square genetic algorithm to estimate the internal parameters of lithium-ion batteries.

Fast and Accurate Calculation of System-Level ESD Noise Coupling to a Signal Trace by PEEC Model Decomposition

A fast and accurate calculation method of system-level electrostatic discharge (ESD) noise coupling based on model decomposition of the partial element equivalent circuit is proposed. The proposed method can significantly reduce the calculation time without loss of accuracy by separating small victim signal traces from large aggressor structures such as ground planes and ESD gun strap. Using the method, the ESD noise coupling at the terminations of a victim signal trace is rigorously calculated and validated with measurements and full-wave simulations in both frequency and time domains.