Combined Micro Research Articles

Sustainable Utilization of Biomass Refinery Wastes for Accessing Activated Carbons and Supercapacitor Electrode Materials.

Biomass processing wastes (humins) are anticipated to become a large-tonnage solid waste in the near future, owing to the accelerated development of renewable technologies based on utilization of carbohydrates. In this work, the utility of humins as a feedstock for the production of activated carbon by various methods (pyrolysis, physical and chemical activation, or combined approaches) was evaluated. The obtained activated carbons were tested as potential electrode materials for supercapacitor applications and demonstrated combined micro- and mesoporous structures with a good capacitance of 370 F g-1 (at a current density of 0.5 A g-1 ) and good cycling stability with a capacitance retention of 92 % after 10 000 charge/discharge cycles (at 10 A g-1 in 6 m aqueous KOH electrolyte). The applicability of the developed activated carbon for practical usage as a supercapacitor electrode material was demonstrated by its successful utilization in symmetric two-electrode cells and by powering electric devices. These findings provide a new approach to deal with the problem of sustainable wastes utilization and to advance challenging energy storage applications.

Increasing the efficiency of enrichment of gold-bearing ore by using combined micro flotation

Increasing the efficiency of enrichment of gold-bearing ore by using combined micro flotation

Histological Analysis of Dentition in Rockshelter Burials from Two Sites in Central Belize

Objectives: Investigations of dental health in the Maya region have frequently focused on individualsburied at urban sites rather than in peripheral or intermediary zones. This study presents a dental analysisof a different type of mortuary sample, those persons buried in two non-elite peripheral rockshelters, in CentralBelize using a combined dental micro- and macrodefect approach to interpret health experience. Materials and Methods: A total of 22 teeth (permanent mandibular canines, and mandibular and maxillarythird molars) from the two sites were assessed for dental caries, enamel hypoplasias, and Wilson bands. Themaximum and minimum ages of microdefect formation for each tooth was calculated. Results: Carious lesions were infrequently represented in the sample, while linear enamel hypoplasias wereexpressed in less than half the sample. Wilson bands, conversely, were present in nearly every tooth indicatingthat the rockshelter populations experienced more acute stress. Individuals interred at Caves Branch Rockshelterwere affected earlier in life based on analysis of mandibular canines. Conclusion: Non-elites buried in rockshelters in Central Belize had similar dental health experiences whencompared with individuals buried at elite centers. At least in terms of oral health, peripheral communities in thisarea were not adversely affected by their distance from urban core sites

Parametric optimization in turning of AA2014/Al2O3 nano composite for machinability assessment using sensors

Aluminium metal matrix nano-composites (AMMNC) reinforced with various weight percentages of micro and nano Al2O3 particles have outstanding mechanical properties for variety of industrial, aerospace and automotive applications. However, the machinability of AMMNC is still a problem. The presence of abrasive particulates behaves like cutting edge for the tool during machining, resulting in unexpected tool wear, high tool workpiece interface temperature, enormous amount of cutting forces and vibration. In this study, experimental investigations were carried out to assess the machinability in turning of AMMNC under dry condition. A mathematical model was developed to predict the responses, namely surface finish, tool wear, work-tool interface temperature and cutting forces using linear regression analysis. Taguchi based optimization technique has been used to optimize the turning parameters for obtaining the best surface roughness of the components with reduced tool wear, temperature and cutting force. Multiple sensors were used to measure the responses to identify the optimum machining parameters. The frequency domain analysis is carried out to predict the dominant frequency band. Chip morphology analysis is also carried out to assess the machinability. Thus, this work helps to know about the effect of combined micro and nano-particles in the properties of AMMNC and its machinability.

Automated Analysis of Spatially Resolved X-ray Scattering and Micro Computed Tomography of Artificial and Natural Enamel Carious Lesions

Radiography has long been the standard approach to characterize carious lesions. Spatially resolved X-ray diffraction, specifically small-angle X-ray scattering (SAXS), has recently been applied to caries research. The aims of this combined SAXS and micro computed tomography (µCT) study were to locally characterize and compare the micro- and nanostructures of one natural carious lesion and of one artificially induced enamel lesion; and demonstrate the feasibility of an automated approach to combined SAXS and µCT data in segmenting affected and unaffected enamel. Enamel, demineralized by natural or artificial caries, exhibits a significantly reduced X-ray attenuation compared to sound enamel and gives rise to a drastically increased small-angle scattering signal associated with the presence of nanometer-size pores. In addition, X-ray scattering allows the assessment of the overall orientation and the degree of anisotropy of the nanostructures present. Subsequent to the characterization with µCT, specimens were analyzed using synchrotron radiation-based SAXS in transmission raster mode. The bivariate histogram plot of the projected data combined the local scattering signal intensity with the related X-ray attenuation from µCT measurements. These histograms permitted the segmentation of anatomical features, including the lesions, with micrometer precision. The natural and artificial lesions showed comparable features, but they also exhibited size and shape differences. The clear identification of the affected regions and the characterization of their nanostructure allow the artificially induced lesions to be verified against selected natural carious lesions, offering the potential to optimize artificial demineralization protocols. Analysis of joint SAXS and µCT histograms objectively segmented sound and affected enamel.

Preparation and characterization of the magnetic superconductor EuSr2RuCu2O8−δ (RuEu-1212) by partial melting

In this study, fine single crystals of the magnetic superconductor EuSr2RuCu2O8−δ (RuEu-1212) were successfully prepared using the partial melting technique. The obtained single crystals had a cubic shape, which coincides with the results of previous studies of RuGd-1212 single crystals. The single crystals had a typical length of 20–30 µm and the diffraction pattern observed from a sample prepared by partial melting was consistent with patterns of previously reported polycrystalline RuEu-1212 samples. A sample subjected to prolonged sintering, which consisted of a large number of combined micro single crystals prepared by partial melting, exhibited a superconducting transition with Tc-onset of 30.9 K and Tc-zero of 10.5 K.

Scalable fabrication and application of nanoscale IDE-arrays as multi-electrode platform for label-free biosensing

The continuous progress in the construction of advanced, miniaturized electrodes provides a promising route towards compact and sensitive biological and chemical sensor platforms. We present a combined micro- and nanofabrication process at wafer-scale with nanoimprint lithography and subsequent photolithography for the realization of ultra-small, interdigitated electrode arrays. Several chips of gold nanoelectrode arrays (NEA) in a 4 × 4 configuration designed as interdigitated electrodes (NEA-IDEs) with finger structures measuring 14 μm in length and 600 nm in width with 600 nm spacing were fabricated simultaneously on 4-inch wafers. Our process involved a nanoimprint lithography step, wet-etching, metal evaporation and nano lift-off followed by optical lithography for metal contact lines and passivation layers. The optimized procedure yielded high-quality NEA-IDEs with reliable electrochemical behavior as inferred from voltammetric and impedimetric analysis. The final array allows the control of all 16 NEA-IDEs in parallel, which can be beneficial for multi-analyte detection. In a proof-of-concept assay, to demonstrate the applicability of the NEA-IDEs for biosensing, the nanostructures were modified with short DNA molecules as recognition elements for the detection of hybridization via impedance spectroscopy. Stable impedance signals were found using the redox system ferri-/ferrocyanide. After hybridization with complementary target DNA the sensors showed an enhancement of the charge transfer resistance. Experiments with different target DNA concentrations demonstrated a dynamic detection range of 1–100 nM. The main advantage of these NEA-IDE structures is that they are small enough to be integrated into typical microchannel dimensions of 50–100 μm for miniaturized lab-on-a-chip biosensor devices in future.

Analysis of combined extrusion micro coining process to manufacture microstructured tappets

In times of enhanced functional integration of machine elements the combination of forming processes offers an opportunity to increase the efficiency of the manufacturing process. Due to mutual interactions combining different forming operations a comprehensive analysis of the processes is necessary especially regarding micro forming processes. Within this study a combined extrusion micro coining process to manufacture microstructured tappets was investigated. The results reveal that the achieved homogeneity on tappet surface is mainly influenced by the microstructure layout applied on the tool components, due to locally widely varying material flow in the coining region.

In-line monitoring of Li-ion battery electrode porosity and areal loading using active thermal scanning - modeling and initial experiment

This work focuses on a new technique called active thermal scanning for in-line monitoring of porosity and areal loading of Li-ion battery electrodes. In this technique a moving battery electrode is subjected to thermal excitation and the induced temperature rise is monitored using an infra-red camera. Static and dynamic experiments with speeds up to 1.5 m min−1 are performed on both cathodes and anodes and a combined micro- and macro-scale finite element thermal model of the system is developed. It is shown experimentally and through simulations that during thermal scanning the temperature profile generated in an electrode depends on both coating porosity (or area loading) and thickness. It is concluded that by inverting this relation the porosity (or areal loading) can be determined, if thermal response and thickness are simultaneously measured.

3-D microstructure of olivine in complex geological materials reconstructed by correlative X-ray μ-CT and EBSD analyses.

We reconstruct the 3-D microstructure of centimetre-sized olivine crystals in rocks from the Almirez ultramafic massif (SE Spain) using combined X-ray micro computed tomography (μ-CT) and electron backscatter diffraction (EBSD). The semidestructive sample treatment involves geographically oriented drill pressing of rocks and preparation of oriented thin sections for EBSD from the μ-CT scanned cores. The μ-CT results show that the mean intercept length (MIL) analyses provide reliable information on the shape preferred orientation (SPO) of texturally different olivine groups. We show that statistical interpretation of crystal preferred orientation (CPO) and SPO of olivine becomes feasible because the highest densities of the distribution of main olivine crystal axes from EBSD are aligned with the three axes of the 3-D ellipsoid calculated from the MIL analyses from μ-CT. From EBSD data we distinguish multiple CPO groups and by locating the thin sections within the μ-CT volume, we assign SPO to the corresponding olivine crystal aggregates, which confirm the results of statistical comparison. We demonstrate that the limitations of both methods (i.e. no crystal orientation data in μ-CT and no spatial information in EBSD) can be overcome, and the 3-D orientation of the crystallographic axes of olivines from different orientation groups can be successfully correlated with the crystal shapes of representative olivine grains. Through this approach one can establish the link among geological structures, macrostructure, fabric and 3-D SPO-CPO relationship at the hand specimen scale even in complex, coarse-grained geomaterials.

Experimental investigation for graphene and carbon fibre in polymer-based matrix for structural applications

Abstract The present paper investigates the behaviour of a polymer matrix beam reinforced with graphene and carbon fibres at nano and micro level reinforcements, respectively, to study mainly the strength aspects for structural applications. However an attempt has also been made to use a combination of both micro and nano level fillers in both individual and combined forms as reinforcements. The addition of graphene and carbon fibres in the control beams was varied from 0.1 to 0.4% percent by weight of polymer matrix. Dispersion of graphene was carried out using ultrasonic energy. Composite beams were tested under flexural in order to evaluate their mechanical property such as load-deflection criteria. These results were then compared with those obtained from plain polymer beams. The present work also investigates the optimum percentage of graphene and carbon fibres as individual and combination fillers that gave the best results in terms of enhanced mechanical properties and economical aspects as well. Scanning electron microscopy and energy dispersion X-ray spectroscopy was conducted to examine the interfacial surface adhesion between the fillers and the polymer matrix. Reinforcement of polymer beams with graphene alone by weight of the polymer matrix showed enhanced results when compared to carbon fibres alone while the use of combined nano and micro reinforcements showed performance lying in between nano and micro fillers in the polymer. Flexural strength is enhanced by 35% compared to plain control beams when graphene was used as reinforcement fillers in the polymer matrix.

Import and innovation: Evidence from Chinese firms

This paper investigates the relationship between imports and innovation by importing firms. We first construct a theoretical model in which imports stimulate innovation through cost-reducing knowledge spillovers. We then employ a combined micro dataset of Chinese manufacturing firms to estimate the effects of imported intermediates on the firm's R&D investment. The dataset allows us to construct firm-year level instruments for importing and exporting that are uncorrelated with the innovation decision of the firm. Our estimations find that: (1) importing intermediates tends to increase importing firms’ R&D intensity; and that (2) exporting also increases importing firms' R&D intensity. Examining the channels through which importing affects innovation, we find that importing from high-income sources has a greater impact on innovation. High-tech firms tend to experience greater increases in innovation intensity, as do private firms. Our results are supported by a series of robustness checks.

Positive welfare state dynamics? Sickness benefits and sickness absence in Europe 1997–2011

Sickness absence is associated with great costs for individuals, companies and society at large. Influenced by neo-classical economic theory, policy advice has emphasized the role of sickness benefit programs for reducing sickness absence rates: too generous benefits without proper control will increase the number of recipients and prolong absence spells as well as possibly cause negative dynamic effects in the long term. This study provides an alternative interpretation of the relationship between sickness benefits and sickness absence. By combining an epidemiological approach to sickness absence and a resource-based approach to welfare, we argue that sickness benefits might be viewed as a “collective resource” that, by providing economic support during times of ill-health, might have positive health effects. Statistical analysis of short-term sickness absence using innovative methodological approaches and combined micro- and macro-level data for 21 EU countries over the period of 1992–2011 indicates that the long run effects of relatively generous sickness benefits is rather to reduce sickness absence. This result also has implications for sickness benefit reform: whereas benefit cuts to some extent may reduce absence in the short run, in the longer run such reforms may actually increase sickness absence rates.

High-Speed for Data Transmission in GSM Networks Based on Cognitive Radio

This paper mainly studies data transmission DT rate in the modern communication systems. Increasing the need to improve the sensitivity of the control systems to detect low signals weak capacity density in view of the increasing communications systems new radio that use the capacity is decreasing and the scope of the taking of spaciousness and frequencies are on the rise. This proposed approaches Methodology: Of the combined macro cellular and micro cellular networks on the principles of the cognitive radio, Provide in parallel with the work of the main GSM network to transfer data at a rate of several tens of megabits per second depending on the High-speed for Data transmission in GSM networks based on Cognitive Radio (CR) technology and its various aspects that may play a very important role in the field of next generation wireless communication networks.

A High-Thrust Screw-Type Piezoelectric Ultrasonic Motor with Three-Wavelength Exciting Mode

A high-thrust screw-type piezoelectric ultrasonic motor with a three-wavelength exciting mode is proposed in this paper. The motor mainly includes a stator and a screw output shaft, and the stator is composed of twelve rectangular piezoelectric plates and a hollow metal elastomer with an internal thread. The stator can be excited to generate the combined micro ultrasonic vibration mode. With this ultrasonic vibration mode, a three-wavelength traveling wave can be synthesized. The three-wavelength traveling wave is used to drive the screw output shaft by means of the frictional force between the stator and the shaft. Rotary-linear motion can be achieved without any additional conversion mechanism. Large thrust output can be easily obtained using a three-wavelength exciting mode. The exciting mode is analyzed in detail. The prototype is designed, simulated, and fabricated. A series of experiments are carried out and the results indicate that the maximum output thrust is 50.8 N at an excitation frequency and peak-to-peak voltage of 28.9 kHz and 120 Vp-p, respectively. The maximum force density is 247.8 N/kg.

The effect of macro/micro combination pore structure of biphasic calcium phosphate scaffold on bioactivity

Cellular responses such as adhesion, spreading, growth and proliferation can be altered by macro and micro pores as well as surface patterns on its surface. In this study, the scaffold was prepared with interconnected macro pores by the polymeric sponge method and with interconnected micro pores by BCP slurry coating with different particle sizes on sintered porous body and necking sintering process. Two particle sizes for micro pores, 200–400nm and 600–800nm, were coated on a pre-sintered porous body. A combined macro and micro pore structure of the BCP scaffold can improve osteoblast cellular activity. In vitro study of MG63 cells suggest that the modified scaffolds improved cell response such as cell spreading, proliferation and differentiation. The scaffold that has a uniform distribution of micro pores ranging 1~5µm in diameter on its surface yields the highest rate of cellular response.

Combined micro-XRF and TXRF methodology for quantitative elemental imaging of tissue samples

Local differences in structural properties of biological specimens pose a major limitation to quantitative X-ray fluorescence imaging. This is because both the various tissue compartments of different density and variation in the sample thickness upon frequently used freeze-drying come up with the different values of the sample mass per unit area to be taken into account. Even though several solutions to tackle this problem based on the home-made standards for quantification in terms of thickness- and density-independent elemental mass fractions have been proposed, this issue is not addressed enough due to the samples’ heterogeneity. In our recent study, we propose a calculation scheme based on combined external-standard micro X-ray fluorescence (micro-XRF) imaging and internal-standard total reflection X-ray fluorescence (TXRF) analysis to determine the corrected elemental mass fraction distributions in commonly analysed rat tissues: kidney, liver and spleen. The results of TXRF analysis of digested large tissue sections together with the mean values of elemental masses per unit area obtained with micro-XRF were employed to determine the average masses per unit area of the samples. The correction for variation of the tissue thickness and density was done through with the use of Compton intensities. Importantly, by its versatility, our novel approach can be used to produce elemental contrast in a variety of biological specimens where local variations in either the sample density or thickness are no longer the issue.

Evaluation of an Integrated Roof Wind Energy System for urban environments

Integrating renewable energy in the urban environment is of importance for the renewable energy goals set by the European Union. This research is to study and evaluate wind energy potential for an Integrated Roof Wind Energy System on the rooftop of the buildings of different heights and in different locations with the help of numerical modelling (CFD). The Navier-Stokes equations are solved using the SIMPLE algorithm while the turbulence is modelled using the k-ω SST equations. All the simulations are performed using OpenFOAM. Results shows that wind speed can be accelerated by ∼1.4 times till it reaches the periphery of the turbine inside the unit, which will increase wind power output considerably. This results in power factor increase of 1.7 for tall buildings. Therefore, enabling combined micro wind and solar energy systems to be a viable option for urban environments.

Microstructure and properties of duplex coatings on magnesium alloy

The duplex Ti cold spray + MAO coatings were deposited on the Mg alloy substrates using combined cold spray and micro arc oxidation (MAO). The microstructure, mechanical property and corrosion resistance of the duplex coatings were investigated compared with the MAO coated Mg alloy substrate. Results indicate that the Ti cold spray coating with 130 µm showed an obvious boundary between the Mg substrate, and the TiO2 phase was formed by MAO on the top coating. The duplex coating showed a little coarse and porous structure, which resulted in low mechanical property and wear resistance compared with the MAO treated Mg substrate. However, it showed an excellent corrosion resistance due to the difference of chemical stability for the coatings. Furthermore, this duplex coating might be very useful for improving the photocatalytic ability of titania due to its markedly increasing specific area.

Immobilizing of heavy metals in sediments contaminated by nonferrous metals smelting plant sewage with sulfate reducing bacteria and micro zero valent iron

Biological treatment method using sulfate reducing bacteria (SRB) is considered as the most promising alternative for heavy metals stabilization and immobilization due to its low cost and high efficiency. In this study, a series of immobilization experiments were conducted with heavy metals contaminated aquifer sediment under three conditions: combined micro zero valent iron with sulfate reduction bacteria (mFe0+SRB), individual sulfate reduction bacteria (SRB) and micro zero valent iron (mFe0) only. The aim of this study was to investigate the immobilization efficiency of Cu, Cd, Zn and Pb under these three conditions (mFe0+SRB, SRB, mFe0). The results presented that the leaching test performance of mFe0+SRB was much better than the contrast tests, the removal efficiencies of Cu, Cd, Zn and Pb (mFe0+SRB) were 100%, 98.5%, 90.69%, 100%, respectively. The heavy metal stability of the treated sample was also evaluated with sequential metal extractions experiments, Cu, Cd, Zn and Pb were found to form more stable mineral phases (for example, residual fraction and oxidizable fraction) in mFe0+SRB conditions. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the mineral phases of treated sediment. According to XRD and XPS characterization, heavy metal may existed in the form of FeO, FeOOH, PbCd, PbZn, ZnS, Zn, CdO, CuZn, and CuS. This study demonstrates that mFe0+SRB could be considered as an efficient way for immobilization of multi heavy metals polluted sediment dredged from Xiawangang River.