Electrokinetic removal of creosote from treated timber waste: a comprehensive gas chromatographic view

The applicability of electro-remediation to remove creosote contaminants from treated wood wastes and to assess the behaviour of its components when submitted to an electric field was studied on woodchips from treated railway sleepers of Pinus pinaster Ait. 15 days experiments were performed using a laboratory cell, with constant current density set at 0.2 mA cm⁻² and an open electrolyte flow rate of 0.5 mL min⁻¹. The anolyte and catholyte solutions were collected and extracted by solid phase extraction. The resulting extracts were analysed by one dimensional gas chromatography hyphenated with mass spectrometry (1D-GC/MS) and comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC × GC/TOFMS). The chemical groups of creosote components were identified and its behaviour on process described. Polycyclic aromatic hydrocarbons, phenols and the majority of the S- and O- heterocycles were found to move in the electrokinetic cell towards the anode compartment, due to electroosmosis, whereas the majority of the positively charged N-heterocycles (aza-heterocycles) moved towards the cathode compartment, due to electromigration.     

Molecular dynamics of adhesion force of single-walled carbon nanotubes

It is of great significance to provide theoretical guidance to the application of carbon nanotubes as adhesive materials via the investigation on their adhesion force. In this paper, molecular dynamics was adopted to investigate the adhesion force between the graphene substrate and the carbon nanotubes with varying deformation degrees and diverse types of irradiation induced defects at different temperatures. No obvious adhesion force was found between the carbon nanotube and graphene until the deformation degree of the former reached > 70%. The adhesion force would be maintained at a high level when the temperature was in the range of 280–320 K, which limited its application. Moreover, the adhesion force between carbon nanotube with vacancies and graphene substrate would decrease with increasing size of vacancies. Finally, compared with monovacancies and divacancies, Stone-Wales defects most remarkably reduced the adhesion force of carbon nanotubes.     

Effect of magnetic nanoparticles on damping property of nature rubber

A new kind of magnetic rubber was prepared by doping Fe₃O₄ nanoparticles into nature rubber matrix, which was characterized by the scanning electron microscopy and X-ray spectroscopy. They showed that the Fe₃O₄ nanoparticles were well dispersed in rubber matrix. Furthermore, the mechanical and magnetic properties of the magnetic rubber were investigated, indicating the improvement of tensile strength from 13.9 to 15.8 MPa and high saturation magnetization (16.7 emu/g) compared with the nature rubber. What’ more, the loss factor of magnetic rubber treated by an external homogenous magnetic field (1.5 T) was improved from 0.07 to 0.15 compared with magnetic rubber without treating by the magnetic field. The result is attributed that after applying a magnetic field, magnetic nanoparticles on the rubber matrix are magnetized; meanwhile, magnetic dipole moments are induced, which causes magnetic field and can absorb shock energy.     

Impacts of Post-metallisation Processes on the Electrical and Photovoltaic Properties of Si Quantum Dot Solar Cells

As an important step towards the realisation of silicon-based tandem solar cells using silicon quantum dots embedded in a silicon dioxide (SiO₂) matrix, single-junction silicon quantum dot (Si QD) solar cells on quartz substrates have been fabricated. The total thickness of the solar cell material is 420 nm. The cells contain 4 nm diameter Si quantum dots. The impacts of post-metallisation treatments such as phosphoric acid (H₃PO₄) etching, nitrogen (N₂) gas anneal and forming gas (Ar: H₂) anneal on the cells’ electrical and photovoltaic properties are investigated. The Si QD solar cells studied in this work have achieved an open circuit voltage of 410 mV after various processes. Parameters extracted from dark I–V, light I–V and circular transfer length measurement (CTLM) suggest limiting mechanism in the Si QD solar cell operation and possible approaches for further improvement.     

Process intensification: water electrolysis in a centrifugal acceleration field

Intensification of hydrogen production by carrying out water electrolysis in a centrifugal acceleration field has been demonstrated. A prototype single cell rotary water electrolyser was constructed, and a number of design challenges with regard to the practical application were addressed. The rotary electrolyser was tested over a range of current density, centrifugal acceleration, electrolyte concentration, temperature, and electrode geometry. The test results showed that at normal cell operating conditions (7.7 M KOH solution, 348 K) much of the cell voltage benefits were achieved at an acceleration of about 16 g (g = 9.81 m s⁻²), equivalent to a rotational speed of 500 rpm (revolution per minute) for the rotary cell. The rotary electrolyser cell voltage was about 0.25–0.5 V, less than the equivalent static cell under similar operating conditions, depending on the current density. The cell voltages achieved, without an effective electrode catalytic coating, were comparable with typical industrial values of fully developed pressurised cells. At a higher acceleration of 41 g, the rotary cell’s current density can be up to 13.5 KA m⁻² without causing gas bubble blinding of the membranes and electrodes. When comparing with typical current densities (about 5 kA m⁻²) found in commercial systems, this study demonstrated the potential of intensification.     

Mathematical analysis of colonial formation of embryonic stem cells in microfluidic system

A fluidic environment affects mechanochemical characteristics of embryonic stem cells (ESCs). Perfusion is recognized as an attractive culture mode of ESCs since the steady fluidic state can enhance ESCs’ controllability, supporting a unique cell culture condition. Cellular membrane motility presents important information about cellular dynamics such as adhesion, spreading, and migration. Thus, an investigation of the perfusion-induced membrane motility is significant to understand the mechanochemical behavior of ESCs in the steady culture state. In this research, we suggest L _fr , the ratio of circumferential membrane unattached to other cells’ to the cell’s circumference, as a new parameter to characterize cells’ shape and motility. L _fr of embryonic stem cells has positive correlations with cellular area (A _r ) and free peripheral length (L _f ) but a negative correlation with roundness (R _n ). We also propose a mathematical model representing ESCs’ membrane motilities and demonstrate their colonical behavior.     

Halloysite nanotubes coated with magnetic nanoparticles

Co nanoparticles were assembled on the surface of halloysite nanotubes (HNTs) to prepare one-dimensional magnetic Co-HNTs via electroless deposition. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectrometry (EDXS) and vibrating sample magnetometer (VSM). The cobalt nanoparticles of 3–7 nm in size were uniformly deposited on the surface of the nanotubes. The remanent magnetization (M_r), saturation magnetization (M_s) and coercivity (H_c) values of the Co-HNTs were 13.9 emu/g, 27.05 emu/g and 1659 O_e, respectively, larger than that of the pure Co nanoparticles (580.72 O_e). A mechanism of the deposition of the magnetic nanoparticles on the surface of the halloysite nanotubes is suggested. Co-HNTs showed an interesting potential in the field of magnetic devices.     

Emissions of N<Subscript>2</Subscript>O from fertilized and grazed grassland on organic soil in relation to groundwater level

Intensively managed grasslands on organic soils are a major source of nitrous oxide (N₂O) emissions. The Intergovernmental Panel on Climate Change (IPCC) therefore has set the default emission factor at 8 kg N–N₂O ha⁻¹ year⁻¹ for cultivation and management of organic soils. Also, the Dutch national reporting methodology for greenhouse gases uses a relatively high calculated emission factor of 4.7 kg N–N₂O ha⁻¹ year⁻¹. In addition to cultivation, the IPCC methodology and the Dutch national methodology account for N₂O emissions from N inputs through fertilizer applications and animal urine and faeces deposition to estimate annual N₂O emissions from cultivated and managed organic soils. However, neither approach accounts for other soil parameters that might control N₂O emissions such as groundwater level. In this paper we report on the relations between N₂O emissions, N inputs and groundwater level dynamics for a fertilized and grazed grassland on drained peat soil. We measured N₂O emissions from fields with different target groundwater levels of 40 cm (‘wet’) and 55 cm (‘dry’) below soil surface in the years 1992, 1993, 2002, 2006 and 2007. Average emissions equalled 29.5 kg N₂O–N ha⁻¹ year⁻¹ and 11.6 kg N–N₂O ha⁻¹ year⁻¹ for the dry and wet conditions, respectively. Especially under dry conditions, measured N₂O emissions exceeded current official estimates using the IPCC methodology and the Dutch national reporting methodology. The N₂O–N emissions equalled 8.2 and 3.2% of the total N inputs through fertilizers, manure and cattle droppings for the dry and wet field, respectively and were strongly related to average groundwater level (R ² = 0.74). We argue that this relation should be explored for other sites and could be used to derive accurate emission data for fertilized and grazed grasslands on organic soils.     

Regulation of Cell Division and Growth in Roots of <Emphasis Type="Italic">Lactuca sativa</Emphasis> L. Seedlings by the <Emphasis Type="Italic">Ent</Emphasis>-Kaurene Diterpenoid Rabdosin B

Rabdosin B, an ent-kaurene diterpenoid purified from the air-dried aerial parts of Isodon japonica (Burm.f) Hara var. galaucocalyx (maxin) Hara, showed a biphasic, dose-dependent effect on root growth and a strong inhibitory effect on root hair development in lettuce seedlings (Lactuca sativa L.). Lower concentrations of rabdosin B (20–80 μM) significantly promoted root growth, but its higher levels at 120–200 μM, by contrast, had inhibitory effects. Additionally, all tested concentrations (10–40 μM) inhibited root hair development of seedlings in a dose-dependent manner. Further investigations on the underlying mechanism revealed that the promotion effect of rabdosin B at the lower concentrations resulted from increasing the cell length in the mature region and enhancing the mitotic activity of meristematic cells in seedlings’ root tips. In contrast, rabdosin B at higher concentrations inhibited root growth by affecting both cell length in the mature region and division of meristematic cells. Comet assay and cell cycle analysis demonstrated that the decrease of mitotic activity of root meristematic cells was due to DNA damage induced cell cycle retardation of the G₂ phase and S phase at different times.     

Nitrous oxide emissions from fertilized and unfertilized grasslands on peat soil

Emissions of nitrous oxide (N₂O) from managed and grazed grasslands on peat soils are amongst the highest emissions in the world per unit of surface of agriculturally managed soil. According to the IPCC methodology, the direct N₂O emissions from managed organic soils is the sum of N₂O emissions derived from N input, including fertilizers, urine and dung of grazing cattle, and a constant ‘background’ N₂O emission from decomposition of organic matter that depends on agro-climatic zone. In this paper we questioned the constant nature of this background emission from peat soils by monitoring N₂O emissions, groundwater levels, N inputs and soil NO₃ ⁻–N contents from 4 grazed and fertilized grassland fields on managed organic peat soil. Two fields had a relatively low groundwater level (‘dry’ fields) and two fields had a relatively high groundwater level (‘wet’ fields). To measure the background N₂O emission, unfertilized sub-plots were installed in each field. Measurements were performed monthly and after selected management events for 2 years (2008–2009). On the managed fields average cumulative emission equaled 21 ± 2 kg N ha⁻¹y⁻¹ for the ‘dry’ fields and 14 ± 3 kg N ha⁻¹y⁻¹ for the ‘wet’ fields. On the unfertilized sub-plots emissions equaled 4 ± 0.6 kg N ha⁻¹y⁻¹ for the ‘dry’ fields and 1 ± 0.7 kg N ha⁻¹y⁻¹ for the ‘wet’ fields, which is below the currently used estimates. Background emissions were closely correlated with groundwater level (R ² = 0.73) and accounted for approximately 22% of the cumulative N₂O emission for the dry fields and for approximately 10% of the cumulative N₂O emissions from the wet fields. The results of this study demonstrate that the accuracy of estimating direct N₂O emissions from peat soils can be improved by approximately 20% by applying a background emission of N₂O that depends on annual average groundwater level rather than applying a constant value.     

Tin Oxide Nanowires: The Influence of Trap States on Ultrafast Carrier Relaxation

We have studied the optical properties and carrier dynamics in SnO₂ nanowires (NWs) with an average radius of 50 nm that were grown via the vapor–liquid solid method. Transient differential absorption measurements have been employed to investigate the ultrafast relaxation dynamics of photogenerated carriers in the SnO₂ NWs. Steady state transmission measurements revealed that the band gap of these NWs is 3.77 eV and contains two broad absorption bands. The first is located below the band edge (shallow traps) and the second near the center of the band gap (deep traps). Both of these absorption bands seem to play a crucial role in the relaxation of the photogenerated carriers. Time resolved measurements suggest that the photogenerated carriers take a few picoseconds to move into the shallow trap states whereas they take ~70 ps to move from the shallow to the deep trap states. Furthermore the recombination process of electrons in these trap states with holes in the valence band takes ~2 ns. Auger recombination appears to be important at the highest fluence used in this study (500 μJ/cm²); however, it has negligible effect for fluences below 50 μJ/cm². The Auger coefficient for the SnO₂ NWs was estimated to be 7.5 ± 2.5 × 10⁻³¹ cm⁶/s.     

Magnetic and Cytotoxicity Properties of La1−x Sr x MnO3 (0 ≤ x ≤ 0.5) Nanoparticles Prepared by a Simple Thermal Hydro-Decomposition

This study reports the magnetic and cytotoxicity properties of magnetic nanoparticles of La_1−x Sr _x MnO₃ (LSMO) with x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5 by a simple thermal decomposition method by using acetate salts of La, Sr, and Mn as starting materials in aqueous solution. To obtain the LSMO nanoparticles, thermal decomposition of the precursor was carried out at the temperatures of 600, 700, 800, and 900 °C for 6 h. The synthesized LSMO nanoparticles were characterized by XRD, FT-IR, TEM, and SEM. Structural characterization shows that the prepared particles consist of two phases of LaMnO₃ (LMO) and LSMO with crystallite sizes ranging from 20 nm to 87 nm. All the prepared samples have a perovskite structure with transformation from cubic to rhombohedral at thermal decomposition temperature higher than 900 °C in LSMO samples of x ≤ 0.3. Basic magnetic characteristics such as saturated magnetization (M _S) and coercive field (H _C) were evaluated by vibrating sample magnetometry at room temperature (20 °C). The samples show paramagnetic behavior for all the samples with x = 0 or LMO, and a superparamagnetic behavior for the other samples having M _S values of ~20–47 emu/g and the H _C values of ~10–40 Oe, depending on the crystallite size and thermal decomposition temperature. Cytotoxicity of the synthesized LSMO nanoparticles was also evaluated with NIH 3T3 cells and the result shows that the synthesized nanoparticles were not toxic to the cells as determined from cell viability in response to the liquid extract of LSMO nanoparticles.     

Preparation of platinum nanoparticles on polyaniline-coat multi-walled carbon nanotubes for adsorptive stripping voltammetric determination of formaldehyde in aqueous solution

Platinum nanoparticles on polyaniline-coat multi-walled carbon nanotubes were fabricated by electrochemical method at paraffin-impregnated graphite electrode (Pt/PAN/MWCNTs). The material was characterized by various methods including field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and electrochemical techniques. The electrode has been effectively applied toward formaldehyde (HCHO) sensing. A good linear response curves from 1 × 10⁻⁹ to 1 × 10⁻³ M can be obtained with a lower detection limit of 4.6 × 10⁻¹¹ M (S/N 3). The successful preparation of nanocomposites opens a new path to fabricate the promising sensor for HCHO.     

Study on thermally conductive ESBR vulcanizates

The thermal conductivities of emulsion polymerized styrene-butadiene rubber (ESBR) vulcanizates filled with alumina (Al₂O₃), zinc oxide (ZnO), carbon nanotubes (CNTs), silicon carbide (SiC), are measured by steady-state method. The effects of types and loadings of the fillers and their mixture on thermal conductivities of the ESBR vulcanizates are investigated. The results show that the thermal conductivity of ESBR vulcanizates filled with alumina or zinc oxide, increases nearly linearly with increasing loading when the filler loading exceeded 20 phr; the ESBR vulcanizates filled with CNTs have the highest thermal conductivity at a given filler loading in comparison with other composite vulcanizates. At a given loading of 100 phr, the ESBR vulcanizate filled with two different particle sizes SiC of 1–3 and 5–11 μm at the mass ratio of 1:1 has the highest thermal conductivity and relatively good mechanical properties. The experimental results are analyzed using Geometric mean model and Agari’s equation to explain the effect of filler types and particle sizes on the formation of thermal conductive networks. The thermal conductivity of the ESBR vulcanizates filled with Al₂O₃ or ZnO or CNTs could be well predicted by optimized parameters using Agari’s equation for a polymer composite filled with mixtures of particles.     

Facile Fabrication of Uniform Polyaniline Nanotubes with Tubular Aluminosilicates as Templates

The uniform polyaniline (PANI) nanotubes, with inner diameter, outer diameter, and tubular thickness of 40, 60, and 10 nm, respectively, were prepared successfully by using natural tubular aluminosilicates as templates. The halloysite nanotubes were coated with PANI via the in situ chemical oxidation polymerization. Then the templates were etched with HCl/HF solution. The PANI nanotubes were characterized using FTIR, X-ray diffraction, and transmission electron microscopy. The conductivity of the PANI nanotubes was found to be 1.752 × 10⁻⁵ (Ω·cm)⁻¹.     

Spatial distribution of soil phosphorus and herbage mass in beef cattle pastures: effects of slope aspect and slope position

Characterizing and assessing spatial distribution of soil phosphorus and herbage mass in relation to landscape properties, land use, or landscape positions is important for understanding how pasture sustainability can be managed and improved properly. Our reason for conducting this study was to determine the effects of different slope aspects and slope positions on spatial distribution of soil phosphorus and herbage mass in subtropical pastures. Soil and forage samples were collected from contiguous south-, north-, east-, and west-facing slopes across different landscape positions (top slope, middle slope, and bottom slope) in 100 ha of bahiagrass (Paspalum notatum)-based pastures from 2003 to 2006 in subtropical region of southeastern USA. Averaged across years, soils on the north-facing slope contained the greatest amount of soil phosphorus (12.4 ± 2.7 mg kg⁻¹) when compared with other slope aspects. Slope aspect may be acting as an important topographic factor influencing local site microclimate mainly because it determines the amount of solar radiation received. The greatest herbage mass (averaged across year) of 2,967 ± 980 kg ha⁻¹ and the highest phosphorus accumulation of 7.7 ± 3.0 kg ha⁻¹ for bahiagrass were from the top slope position. There was a significant (P ≤ 0.05) decrease in the average herbage mass and phosphorus accumulation with decreasing slope (top to middle slope). Between the top slope and the bottom slope, herbage mass declined from 2,967 ± 980 to 1,805 ± 370 kg ha⁻¹ while phosphorus accumulation was reduced by approximately 40% (7.7–4.6 kg ha⁻¹). Results of our study may increase awareness on how the arrangement of food, water, and shelter and their interactions with topographic and landscape features can significantly influence the movement of animals and utilization of different pastures’ resources. While our study supports our hypothesis that slope aspect and slope position could be of relative importance in controlling spatial distribution of soil phosphorus and herbage mass, broad knowledge of cattle movement in pasture situations is as critical to understanding their impact on agro-ecosystems.     

Iron-filled multiwalled carbon nanotubes surface-functionalized with paramagnetic Gd (III): A candidate dual-functioning MRI contrast agent and magnetic hyperthermia structure

A simple wet chemical method involving only sonication in aqueous GdCl₃ solution was used for surface functionalization of iron-filled multiwalled carbon nanotubes with gadolinium. Functional groups on the sidewalls produced by the sonication provide active nucleation sites for the loading of Gd³⁺ ions. Characterization by EPR, EELS, and HRTEM confirmed the presence of Gd³⁺ ions on the sidewall surface. The room temperature ferromagnetic properties of the encapsulated iron nanowire, saturation magnetization of 40 emu/g and coercivity 600 Oe, were maintained after surface functionalization. Heating functionality in an alternating applied magnetic field was quantified through the measurement of specific absorption rate: 50 W/g_Fe at magnetic field strength 8 kA/m and frequency of 696 kHz. These results point to candidacy for dual-functioning MRI imaging and magnetic hyperthermia structures for cancer therapy.     

Electrophoretic deposition of macroporous carbon nanotube assemblies for electrochemical applications

Electrophoretic deposition of macroporous assemblies of single-walled carbon nanotubes (SWCNTs) is described. The macroporous structure was created thanks to the presence of polystyrene (PS) beads which were co-deposited with the carbon nanotubes in a 60 V potential field. The ratio between the quantity of carbon nanotubes and polystyrene beads in the solution for deposition was found to be critical for the proper self-assembly of the composite film during electrophoretic deposition. The macroporous films have been characterized by scanning electron microscopy, atomic force microscopy and profilometry. The macroporosity was revealed after template removal (calcination of the PS beads). Access to the internal surface was assessed by electrochemical characterization using methylene green as a redox probe likely to adsorb on the SWCNT surface. Platinum nanoparticles and a sol–gel layer with encapsulated dehydrogenase and NAD⁺ cofactor have been deposited on the macroporous SWCNT electrodes in order to illustrate the use of the macropore texture for the detection of H₂O₂ and for biosensor applications, respectively.     

Graphene based multifunctional superbots

A versatile graphene coated glass microswimmer displayed directed motions under the influence of applied electric field, chemical potential gradient and external magnetic field. The directed chemical locomotion took place from the region of lower to higher pH with speed ∼13 body lengths per second due to asymmetric catalytic decomposition of dilute hydrogen peroxide across the motor surface. The negative surface potential of graphene coated motor developed an electrical double layer in an alkaline medium which in turn engendered electrophoretic mobility towards anode when the external electrostatic field was applied. Inclusion of sparsely populated ferromagnetic iron nanoparticles on the surface of the motor offered the magnetic remote control on the motion. The coupled in situ and external controls enabled the motor to develop complex motions in diverse open and confined environments. For example, the motor could approach, pick-up, tow, and release a heavy cargo inside microchannel. Remarkably, the motor (∼67 μg) could successfully drive out a ∼1000 times heavier payload (∼0.67 mg) displaying the ability to overcome the drag force of ∼2619 pN with the help of coupled in situ and remote guidance.     

Long-term effects of balanced fertilization on grass forage yield,quality and nutrient uptake,soil organic C and N,and some soil quality characteristics

Many soils in the Parkland region of the Canadian Prairie contain insufficient amounts of plant-available S and N for high crop yields. Two field experiments (Experiment 1 1980–2005 and Experiment 2 1996–2005) were conducted on a Dark Gray Chernozem (Boralfic Boroll) loam soil at Canwood in north-central Saskatchewan, Canada, to determine the effects of long-term N, S and/or K fertilization to grass on mean forage dry matter yield (DMY), nutrient (N, S and K) concentration and nutrient uptake (averaged over years), and root mass, soil pH, total organic C (TOC) and N (TN), light fraction organic matter (LFOM), C (LFC) and N (LFN), mineralizable C and N, and extractable ammonium-N and nitrate-N in May 2006 (after 26 or 10 growing seasons). Experiment 2 additionally compared the effects of ‘hay-on’ (cut hay not removed) versus ‘hay-off’ (hay removed) on the plant and soil parameters. Experiment 1 had annual treatments of no fertilizer, N, NS and NSK fertilizers from 1980 to 2005, and Experiment 2 received no fertilizer, N, S and NS fertilizers from 1996 to 2005 under ‘hay-on’ and ‘hay-off’ conditions. While DMY, nutrient uptake and root mass were little affected by application of N or S alone compared with the unfertilized treatment, they were substantially increased by application of both N and S together. Co-application of N, S and K fertilizers increased DMY, nutrient uptake and root mass compared with NS application in Experiment 1. Nitrogen concentration in forage was highest in the N only treatment, followed by NS, and then nil, S or NSK treatments. The concentration of K in forage decreased in the order of treatments: NSK > nil or S treatment > N or NS; and of S: NS or S treatment > NSK treatment > nil treatment > N only treatment. Nutrient uptake was influenced more by forage DMY than nutrient concentration. In Experiment 2, DMY and N and K uptakes were greater under ‘hay-on’ than ‘hay-off’ conditions. Soil pH to 15-cm depth was decreased by NSK fertilization. The amounts of TOC, TN, LFOM, LFC, LFN, and mineralizable C and N in the 0–10 cm soil were increased considerably by the co-application of N and S fertilizers. The increase in soil C correlated well with the increase in DMY or root mass resulting from balanced fertilization. Not removing hay resulted in substantially increased LFOM, LFC and LFN contents in soil. The accumulation and downward movement of nitrate-N in the soil profile was decreased with NS application compared with N alone. In conclusion, application of N and S fertilizers together to soil deficient in both N and S produced high forage yield, nutrient uptake and root mass while also reducing soil pH, increased C and N sequestration in soil, and minimized accumulation and downward movement of nitrate-N in the soil profile.