Biological performance of wood–plastic composites containing zinc borate: Laboratory and 3-year field test results

Six different formulations of wood–plastic composites (WPC) fabricated from wood and polypropylene (PP) were tested in the laboratory against decay and termites and in a protected above-ground field test in southern Japan. Variables examined included comparisons of untreated and zinc borate (ZnB) incorporated formulations, wood content ratio, wood particle size and increased surface area via surface grooves (channels) to promote moisture infusion. A standard method originally designed to test durability of solid wood was modified for testing WPC. Wood decay fungi and Formosan subterranean termite activity in laboratory and field tests resulted in different mass losses, post-decay moisture contents and field test ratings depending on their wood and ZnB content. The results show that as wood content increased, mass losses also increased. Addition of ZnB at 1% (w/w) retention level significantly decreased mass losses of wood–plastic composite when exposed to laboratory decay and termite tests. The effects of surface grooves and wood particle size were less important, compared to wood particle content. All WPC tested were highly resistant to fungal decay under protected above-ground field conditions during 36 months. Termite attack, on the other hand, started at earlier stage reducing mean ratings 1 year after the installation.     

Impact of hardening conditions on to stabilized/solidified products of cement–sewage sludge–jarosite/alunite

The main objective of this work is to investigate a viable alternative for the final disposal of sewage sludge from urban wastewater treatment plants using a mixture with cement and jarosite/alunite (J/A) precipitate to develop new construction materials. J/A precipitate is a waste product of a new hydrometallurgical process, which was developed in order to treat economically low-grade nickel oxide ores. In the current study two methods were used for the hardening of the stabilized/solidified products: (1) in laboratory conditions and (2) in accelerated conditions (autoclave treatment).For this purpose, mortar prism samples of 4 × 4 × 16 cm in dimension were prepared, composed of 50% sewage sludge, 30% cement and 20% jarosite/alunite. The samples were treated in an autoclave for 3 h at a temperature of 200 °C and a pressure of 16 bar as well as in laboratory conditions for 28 and 90 days. Compressive and bending strength, while chemical, XRD, thermal analysis, as well as tests of leaching, were tested according to the standard/principal methods of toxicity characteristics leaching procedure (TCLP) and CEN/TS 14405. The results indicated that stabilized/solidified products can be produced for use in construction and that the heavy metals of sludge can be contained in the cement and jarosite/alunite mixture.     

Effect of oxygen partial pressure on microstructural and optical properties of titanium oxide thin films prepared by pulsed laser deposition

Nanocrystalline titanium oxide (TiO₂) thin films were deposited on silicon (1 0 0) and quartz substrates at various oxygen partial pressures (1 × 10⁻⁵ to 3.5 × 10⁻¹ mbar) with a substrate temperature of 973 K by pulsed laser deposition. The microstructural and optical properties were characterized using Grazing incidence X-ray diffraction, atomic force microscopy, UV–visible spectroscopy and photoluminescence. The X-ray diffraction studies indicated the formation of mixed phases (anatase and rutile) at higher oxygen partial pressures (3.5 × 10⁻² to 3.5 × 10⁻¹ mbar) and strong rutile phase at lower oxygen partial pressures (1 × 10⁻⁵ to 3.5 × 10⁻³ mbar). The atomic force microscopy studies showed the dense and uniform distribution of nanocrystallites. The root mean square surface roughness of the films increased with increasing oxygen partial pressures. The UV–visible studies showed that the bandgap of the films increased from 3.20 eV to 3.60 eV with the increase of oxygen partial pressures. The refractive index was found to decrease from 2.73 to 2.06 (at 550 nm) as the oxygen partial pressure increased from 1.5 × 10⁻⁴ mbar to 3.5 × 10⁻¹ mbar. The photoluminescence peaks were fitted to Gaussian function and the bandgap was found to be in the range ∼3.28–3.40 eV for anatase and 2.98–3.13 eV for rutile phases with increasing oxygen partial pressure from 1 × 10⁻⁵ to 3.5 × 10⁻¹ mbar.     

The fatigue behavior of irradiated Reactor Pressure Vessel steel

Fatigue specimens of A508-3 steel were irradiated in the swimming-pool test reactor in China Institute of Atomic Energy, the fluence was 3 × 10¹⁹ n/cm² at 300 °C, then low-cycle fatigue tests were carried out at ambient temperature, with the fatigue strain range is 0.32–1.8%. The results indicate that, irradiated A508-3 specimens exhibit cyclic softening and instability behavior during the test, and the cyclic softening rate increased with strain range increased; fatigue life decreased from 1.7 × 10⁵ to about 5 × 10², as the strain range increased from 0.32% to 1.8%, the fatigue life of A508-3 steel increased after the neutron irradiation; fatigue fracture initiated at the surface of specimen, and more individual cracks formed on the specimens of higher strain range compared with the specimens of lower strain range.     

Construction of Tm3+-PVC membrane sensor based on 1-(2-thiazolylazo)-2-naphthol as sensing material

In this study, a new thulium(III) membrane sensor was constructed. The proposed membrane sensor was fabricated based on a membrane containing 2% sodium tetraphenyl borate (NaTPB) as an anionic additive, 65% benzyl acetate (BA) as solvent mediator, 3% 1-(2-thiazolylazo)-2-naphthol (TN) as ionophore, and 30% poly(vinyl chloride) (PVC). The proposed Tm³⁺ electrode exhibits a Nernstian response of 19.5 ± 0.2 mV per decade of thulium concentration, and has a lower detection limit of 8.7 × 10^? 7 mol L^? 1. The linear range of the sensors was 1.0 × 10^? 6 to 1.0 × 10^? 2 mol L^? 1. It works well in the pH range of 3.2–9.5. Moreover, the recommended selective sensor revealed a comparatively satisfactory selectivity regarding most of the alkali, alkaline earth, some transition and heavy metal ions. The membrane sensor was applied to the determination of fluoride ions in mouth wash samples.     

Application of 1-ethyl-3-(2,5-dihydro-4-(3,5-dimethyl-1H-pyrazol-4-yl)-5-oxo-1H-pyrazol-3-yl)thiourea as sensing material for construction of Tm3+-PVC membrane sensor

A thulium(III) membrane sensor was made using 2% sodium tetraphenyl borate (NaTPB), 65% dibutylphthalate (DBP), 30% poly(vinyl chloride) (PVC) and 3% 1-ethyl-3-(2,5-dihydro-4-(3,5-dimethyl-1H-pyrazol-4-yl)-5-oxo-1H-pyrazol-3-yl)thiourea (ET) as an ionophore. Conductometric study shows selectivity of the Et toward Tm³⁺ ions. Nernstian response of 19.6 ± 0.4 mV per decade of thulium concentration was observed, and the electrode worked well in concentration range of 1.0 × 10^? 6 to 1.0 × 10^? 2 mol L^? 1 with a lower detection limit (LDL) of 7.2 × 10^? 7 mol L^? 1, in a pH range of 4.3–10.4. The selectivity of the sensor over alkaline, alkaline earth, transition and heavy metal ions was also found to be in a satisfactory range. To check the analytical applicability of the proposed Tm³⁺ sensor, it was successfully used as an indicator electrode in analysis of thulium in certified reference materials.     

Effect of stitch density on fatigue characteristics and damage mechanisms of stitched carbon/epoxy composites

The effect of stitch density (SD) on fatigue life, stiffness degradation and fatigue damage mechanisms in carbon/epoxy (T800SC/XNRH6813) stitched using Vectran thread is presented in this paper. Moderately stitched composite (SD = 0.028/mm²; ‘stitched 6 × 6’) and densely stitched composite (SD = 0.111/mm²; ‘stitched 3 × 3’) are tested and compared with composite without stitch thread (SD = 0.0; ‘unstitched’). The experiments show that the fatigue life of stitched 3 × 3 is moderately better than that of unstitched and stitched 6 × 6. Stitched 3 × 3 pattern is also able to postpone the stiffness degradation onset. The improvement of fatigue properties and postponement of stiffness degradation onset in stitched 3 × 3 is primarily due to an effective impediment of edge-delamination. Quantification of damage at various cycles and stress levels shows that stitch density primarily affects the growth rate of delamination.     

Effect of Al-doped ZnO film thickness on periodic GaAs subwavelength grating structures for photovoltaic device applications

We investigated the effect of Al-doped zinc oxide (AZO) films with different thicknesses deposited onto periodic cone-shaped GaAs subwavelength grating (SWG) structures on their physical properties. As the AZO deposition time was increased, the surface morphology of AZO deposited GaAs SWGs was changed. These structures exhibited the surface reflection of <～6.8% at 300–1200 nm because of their effective graded index distribution between air and the GaAs substrate via the AZO deposited GaAs SWGs, producing a lowest average reflectance of ～2.1% at 40 min of deposition time. With increasing the deposition time, the crystallinity of the AZO films deposited on GaAs SWGs was enhanced, which leaded to the decrease of the effective resistivity up to ～1.55 × 10^?3 Ω-cm at 100 min. The wetting behavior of a water droplet on the surface of samples was also studied.     

Determination of zinc(II) ions in waste water samples by a novel zinc sensor based on a new synthesized Schiff's base

A highly selective and sensitive zinc ion-selective membrane electrode based on N,N′-phenylenebis (salicylideaminato) (L) as a new carrier is reported. The membrane is composed of poly (vinyl chloride) (PVC), o-nitrophenyl octyl ether (NPOE) as plasticizer, potassium tetrakis(p-chlorophenyl) borate (KTpClPB) as lipophilic ionic additive, and L as sensing material. The proposed electrode displays a Nernstian response to Zn²⁺ ions over a wide concentration range of 5.0 × 10^? 7–1.0 × 10^? 1 M with the slope of 29.4 ± 0.2 mV per decade and a detection limit of 2.6 × 10^? 7 M. The sensor has a relatively fast response time of < 10 s and it can be used in the pH range of 3.0–7.0 for at least 2 months without any significant divergency in potential. The selectivity coefficients for mono-, di-, and trivalent cations indicate the good selectivity of sensor for Zn²⁺ ions over a large number of interfering cations. As a result the proposed electrode was applied to Zn²⁺ ions determination in mixture solutions and wastewater samples.     

Influence of air annealing temperature and time on the optical properties of Yb:YAG single crystal grown by HDS method

8 at.% Yb:YAG plate single crystal with the dimension of 170 mm × 150 mm × 30 mm was grown in vacuum by Horizontal Directional Solidification method. Aimed at blue-green color centers, annealing treatments of 15 mm × 15 mm × 1 mm samples from 900 °C to 1400 °C for 5 h and at 900 °C from 5 h to 40 h in air were conducted. The absorption spectra, emission spectra, fluorescence lifetime and X-ray photoelectron spectroscopy of samples under different annealing conditions were measured at room temperature, respectively. Annealing at above 1000 °C for 5 h or at 900 °C for 40 h made the blue-green color centers disappear and the samples turned to transparent. Absorption coefficients decreased in the 300 nm–800 nm wavelength range, emission intensities increased and emission bands broadened around 486 nm and 1029 nm with increasing temperature up to 1200 °C, then varied inversely. These values decreased or increased monotonically with increasing annealing time at 900 °C. The maximal increases of fluorescence lifetime were 62.3% and 64.7%, respectively. The calculated emission cross section of 1200 °C for 5 h was up to 4.4 × 10⁻²⁰ cm². In X-ray photoelectron spectroscopy, the concentrations of oxygen vacancies reduced from 1.28% down to absence by annealing. These experiments show that color centers are detrimental to the optical properties of HDS-Yb:YAG laser crystal and optimal annealing treatments should be conducted.     

Chemical bonding and optoelectrical properties of ruthenium doped yttrium oxide thin films

Highly infrared transparent conductive ruthenium doped yttrium oxide (RYO) films were deposited on zinc sulfide and glass substrates by reactive magnetron sputtering. The structural, optical, and electrical properties of the films as a function of growth temperature were studied. It is shown that the sputtered RYO thin films are amorphous and smooth surface is obtained. The infrared transmittance of the films increases with increasing the growth temperature. RYO films maintain greater than ∼65% transmittance over a wide wavelength range from 2.5 μm to 12 μm and the highest transmittance value reaches 73.3% at ∼10 μm. With increasing growth temperature, the resistivity changed in a wide range and lowest resistivity of about 3.36 × 10⁻³ Ω cm is obtained at room temperature. The RYO thin films with high conductivity and transparency in IR spectral range would be suitable for infrared optical and electromagnetic shielding devices.     

Strontium PVC-membrane sensor based on 2-[(2-mercaptophenylimino)methyl]phenol

The 2-[(2-mercaptophenylimino)methyl]phenol (MPMP) was used as an excellent ionophore in the construction of a Sr²⁺ PVC-based membrane sensor. The best performance was obtained with a membrane composition of 30% poly(vinyl chloride), 62% nitrobenzen (NB), 5.5% MPMP and 2.5% sodium tetraphenyl borate (NaTBP). This sensor demonstrates a good selectivity and sensitivity towards the strontium ion for many cations, including alkali, alkaline earth, transition and heavy metal ions. The sensor revealed a great enhancement in selectivity coefficients for strontium ions in comparison with the previously reported strontium sensors. The proposed sensor exhibits a Nernstian behavior (with a slope of 29.6 ± 0.3 mV per decade) for the concentration range of (1.0 × 10^− 6–1.0 × 10^− 1 M) with a detection limit of 5.5 × 10^− 7 M (48.2 ng/mL). It illustrates a relatively fast response time in the whole concentration range (< 10 s) and it can be used for at least 10 weeks in a pH range of 2.8–9.6. The developed sensor was successfully used as an indicator electrode in the Sr(II) titration with EDTA and the Sr²⁺ ion recovery from binary mixtures.     

Impact of high dose krypton ion irradiation on corrosion behavior of laser beam welded zircaloy-4

In order to study the effect of krypton ion irradiation on the aqueous corrosion behavior of laser beam welded zircaloy-4 (LBWZr4), the butt weld joint of zircaloy-4 was made by means of a carbon dioxide laser, subsequently the LBWZr4 samples were irradiated with Kr ions using an accelerator at an energy of 300 keV, with a dose range from 1 × 10¹⁵ to 3 × 10¹⁶ ions/cm² at about 150 °C. Three-sweep potentiodynamic polarization measurement was employed to evaluate the aqueous corrosion behavior of Kr-irradiated LBWZr4 in a 0.5 M H₂SO₄ solution. Scanning electron microscopy (SEM) was used to examine the surface topography of the Kr-irradiated LBWZr4 after the potentiodynamic polarization measurement. Transmission electron microscopy was employed to examine the change of microstructures in the irradiated surface. The polarization tests showed that compared with the passive current density of the as-received LBWZr4, the Kr-irradiated LBWZr4 is much lower; however, with the irradiation dose increasing from 1 × 10¹⁵ to 3 × 10¹⁶ ions/cm², the passive current density, closely related to the surface corrosion resistance, increased remarkably. The mechanism of the corrosion behavior transformation was due to the recrystallization of the amorphous phase induced by the lower ion irradiation.     

Strain and damage monitoring in carbon-nanotube-based composite under cyclic strain

The resistive behavior of multi-walled carbon nanotube (MWCNT)/epoxy resins, tested under mechanical cycles and different levels of applied strain, was investigated for specimens loaded in axial tension. The surface normalized resistivity is linear with the strain for volume fraction of MWCNTs between 2.96 × 10⁻⁴ and 2.97 × 10⁻³ (0.05 and 0.5% wt/wt). For values lower than 0.05% wt/wt, close to the electrical percolation threshold (EPT) a non-linear behavior was observed. The strain sensitivity, in the range between 0.67 and 4.45, may be specifically modified by controlling the nanotube loading, in fact the sensor sensitivity decreases with increasing the carbon nanotubes amount. Microscale damages resulted directly related to the resistance changes and hence easily detectable in a non-destructive way by means of electrical measurements. In the fatigue tests, the damage is expressed through the presence of a residual resistivity, which increases with the amount of plastic strain accumulated in the matrix.     

Effect of temperature on low velocity impact damage and post-impact flexural strength of CFRP assessed using ultrasonic C-scan and micro-focus computed tomography

The effect of temperature on the low velocity impact resistance properties and on the post-impact flexural performance of CFRP laminates were studied. With this aim, 150 × 75 mm cross-ply carbon fibre/epoxy laminates with a [0/90/90/0]_2s layup, therefore with a total of sixteen layers, were impacted at ambient temperature (30 °C) and at elevated temperatures (55, 75 and 90 °C) at a velocity of 2 m/s using a drop weight impact tower. This was followed by flexural tests carried out at ambient temperature using a three-point bending rig. Damage assessment of impact and post-impact behaviour were carried out using ultrasonic C-scan and microfocus X-ray computed tomography (μCT). Interrupted flexural tests using μCT allowed delamination propagation to be observed. In general, lower projected damage was observed at elevated temperatures, which resulted also in a possible hindrance to delamination and shear cracks propagation during impact and in a greater amount of retained flexural strength after impact.     

Praseodymium analysis in aqueous solution by Pr3+–PVC membrane sensor based on N,N′-bis(4-hydroxysalicylidene)-1-3-phenylenediamine

A new Pr³⁺ poly vinyl chloride PVC membrane sensor based on a membrane containing 3% N,N′-bis(4-hydroxysalicylidene)-1-3-phenylenediamine (HSPDA) as an ionophore, 2% sodium tetraphenyl borate (NaTPB) as an anionic additive, 65% benzyl acetate (BA) as solvent mediator and 30% poly(vinyl chloride) was prepared. This sensor responds to praseodymium ion in a wide linear dynamic range of 1.0 × 10^?6 to 1.0 × 10^?2 mol L^?1 with Nernstian slope of 19.8 ± 0.4 mV per decade and a detection limit of 5.7 × 10^?7 mol L^? 1 in pH range of 3.1 to 9.8. It has a fast response time of ~5 s in the whole concentration range, and can be used for at least 2 months without any considerable divergences in the potentials. The proposed sensor displays an excellent selectivity for Pr³⁺ ions with respect to a large number of alkali, alkaline earth, transition and heavy metal ions. The developed sensor was successfully applied as an indicator electrode in Pr³⁺ ion potentiometric titration with EDTA, and in direct determination of fluoride ion in two mouth wash samples.     

Effect of annealing on conversion efficiency of nanostructured CdS/CuInSe2 heterojunction thin film solar cell prepared by chemical ion exchange route at room temperature

We report, the effect of air annealing on solar conversion efficiency of chemically grown nanostructured heterojunction thin films of CdS/CuInSe₂, such 100, 200 and 300 °C air annealed thin films characterized for physicochemical and optoelectronic properties. XRD pattern obtained from annealed thin films confirms tetragonal crystal geometry of CuInSe₂ and an increase in average crystallite size from 16 to 32 nm. An EDAX spectrum confirms expected and observed elemental composition in thin films. AFM represents high energy induced grain growth and agglomeration due to polygonization process. Increase in optical absorbance strength and decrease in energy band gap from 1.36 to 1.25 eV is observed. Increase in charge carrier concentration from 2 × 10¹⁶ to 8 × 10¹⁷ cm^?3 is observed as calculated from Hall effect measurements and an enhancement in solar conversion efficiency from 0.26 to 0.47% is observed upon annealing.     

Repair of shear-deficient normal weight concrete beams damaged by thermal shock using advanced composite materials

The use of advanced composite materials such as Fiber Reinforced Polymers (FRPs) in repairing and strengthening reinforced concrete structural elements has been increased in the last two decades. Repairing and strengthening damage structures is a relatively new technique. The aims of this study was to investigate the efficiency and effectiveness of using Carbon Fiber Reinforced Polymer (CFRP) to regain shear capacity of shear-deficient normal weight high strength RC beams after being damaged by thermal shock. Sixteen high strength normal weight RC beams (100 × 150 × 1400 mm) were cast, heated at 500 °C for 2 h and then cooled rapidly by immersion in water, repaired, and then tested under four-point loading until failure. The composite materials used are carbon fiber reinforced polymer plates and sheets. The experimental results indicated that upon heating then cooling rapidly, the reinforced concrete (RC) beams exhibited extensive map cracking without spalling. Load carrying capacity and stiffness of RC beams decreased about 68% and 64%, respectively, as compared with reference beams. Repairing the thermal damaged RC beams allowed recovering the original load carrying without achieving the original stiffness. Repaired beams with CFRP plates with 90° and 45° regained from 90% to 99% of the original load capacity with a corresponding stiffness from 79% to 95%, whereas those repaired with CFRP sheet on the web sides and a combination of CFRP plates and sheet regained from 102% to 107% of the original load capacity with a corresponding stiffness from 81% to 93%, respectively. Finally, finite element analysis model is developed and validated with the experimental results. The finite element analysis showed good agreement as compared with the experimental results in terms of load–deflection and load–CFRP strain curves.     

Preparation of cobalt oxide from concentrated cathode material of spent lithium ion batteries by hydrometallurgical method

Cobalt oxide was prepared from spent lithium ion batteries (LIBs) by reductive leaching, copper sulfide precipitation, cobalt oxalate precipitation and thermal decomposition. The cobalt rich non-magnetic ?16 mesh fraction obtained from spent LIBs by mechanical separation was leached using 2 M H₂SO₄, 6 vol% H₂O₂, reaction temperature 60 °C, agitation speed 300 rpm, pulp density 100 g/L, reaction time 1 h. The leaching efficiency of cobalt was more than 99% and its concentration was 27.4 g/L. Copper was removed (99.9%) as CuS by precipitating with Na₂S. The crystalline solid CoC₂O₄·2H₂O selectively precipitated by treating the copper-free liquor with oxalic acid was calcined to produce crystalline Co₃O₄, of which primary average particle size was 340 nm.     

Effect of aluminum oxide doping on the structural,electrical, and optical properties of zinc oxide (AOZO) nanofibers synthesized by electrospinning

Zinc oxide nanofibers doped with aluminum oxide were prepared by sol–gel processing and electrospinning techniques using polyvinylpyrrolidone (PVP), zinc acetate and aluminum acetate as precursors. The resulting nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–Vis spectroscopy, and current–voltage (I–V) properties. The nanofibers had diameters in the range of 60–150 nm. The incorporation of aluminum oxide resulted in a decrease in the crystallite sizes of the zinc oxide nanofibers. Aluminum oxide doped zinc oxide (AOZO) nanofibers exhibited lower bandgap energies compared to undoped zinc oxide nanofibers. However, as the aluminum content (Al/(Al + Zn) × 100%) was increased from 1.70 at.% to 3.20 at.% in the electrospinning solution, the bandgap energy increased resulting in lower conductivity. The electrical conductivity of the AOZO samples was found to depend on the amount of aluminum dopant in the matrix as reflected in the changes in oxidation state elucidated from XPS data. Electrospinning was found to be a productive, simple, and easy method for tuning the bandgap energy and conductivity of zinc oxide semiconducting nanofibers.