Effect Of Small Amounts Research Articles

Effects of partial substitution of calcium alumino-titanate on the properties and microstructure of mullite–cordierite composites

In order to realize the recycling of calcium alumino-titanate (CAT, a solid waste), the effect of small amounts (3–9% weight ratio) of CAT on the sintering properties of the mullite–cordierite system was investigated. The thermal-shock stability, volume stability, and mechanical properties of samples with different amounts of CAT were characterized and tested. The influence of CAT on the phase composition and microstructure of the mullite–cordierite system was also deduced from thermodynamic calculations. Experimental results, which agreed with the calculations, demonstrate that CAT could promote the close combination and aggregation of matrix materials, thus strengthening the consolidation process and enhancing desirable properties.

Effects of Ce-Rich Misch Metal on the Microstructures and Tensile Properties of as-Cast Mg-7Al-3Sn-1Zn Alloys

The effects of small amounts of Ce-rich misch metal (Mm: 0.5, 1.0 and 2.0 wt.%) addition on the microstructure and tensile properties of as-cast Mg-7Al-3Sn-1Zn wt.% (ATZ731) alloy have been investigated. The addition of Mm restricts the formation of the Mg17Al12 phase but greatly promotes the Al4Mm phase. The proper Mm addition enhances the strength and ductility of ATZ731 alloys at both room temperature (RT) and 175 °C. ATZ731 alloys with 1.0 wt.% Mm addition exhibit an advantageous combination strength and ductility, with the ultimate tensile strength (UTS), 0.2% yield strength (YS) and elongation to failure (Ef) at 175 °C of ~148 MPa, ~102 MPa and ~28%, improved by ~14.7%, ~24.3% and ~53.8%, respectively, compared to those of ATZ731 alloy. This enhancement is primarily owing to the refined microstructures and the high thermal stability of Al4Mm at the elevated temperature in contrast with that of the Mg17Al12 phase. The fracture modes are also discussed.

水素ガス中に含まれる微量な不純物が鋼中への水素侵入挙動に及ぼす影響の評価法の開発

水素ガス中に含まれる微量な不純物が鋼中への水素侵入挙動に及ぼす影響の評価法の開発

Cation exchange behavior during the redox switching of poly (3,4-ethylenedioxythiophene) films

Poly (3,4-ethylenedioxythiophene), PEDOT, films were synthesized at room temperature by potentiodynamic and potentiostatic step deposition in aqueous solutions containing EDOT monomer and LiClO4. In some solutions, the effect of small amounts of sodium dodecylsulfate, SDS, on the polymerization rate of EDOT and on the stiffness of the obtained PEDOT film was studied. The obtained PEDOT films were transferred in aqueous solutions containing cations with different molar mass, such as H+, Li+, Na+, K+, and Cs+. The apparent molar masses of the exchanged species during potentiodynamic experiments were determined by in situ microgravimetry. These measurements underlined the importance of the electrolyte chosen for electropolymerization process. It is known that SDS anions can be trapped inside the polymer layer during electropolymerization, providing them with a cation exchange behavior. However, even if the PEDOT films were deposited from an electrolyte without SDS, they still acted as cation exchangers.

Natural fiber-induced degradation in PLA-hemp biocomposites in the molten state

The effect of small amounts (≤3 wt%) of short hemp fibers on stability of a poly(lactic acid) (PLA) in the molten state is investigated through time-resolved rheology. The decrease over time of the zero-frequency complex viscosity was correlated to severe hydrolytic degradation of the PLA matrix. A kinetic model that accounts for thermal degradation and hydrolysis was fitted to the experimental viscosity data. The significant fiber-induced hydrolysis is due to traces of residual water bound to the fibers inside the composites after the processing steps. A significant mitigation of the fiber-induced PLA hydrolysis can be obtained by carefully drying the hemp fibers before melt compounding and (to a lesser extent) by subjecting the fibers to an alkaline treatment. On the other hand, if the interest is a shorter persistence in the environment, natural fibers can be exploited to accelerate degradation of biocomposites.

Biodegradable composites of recycled thermoplastic starch and sawdust: the effect of cellulose nanofibers, nanoclay and temperature

Studies were performed on the effects of small amounts of cellulose nanofibers and nanoclay particles on mechanical, physical and morphological properties of biodegradable composites of recycled thermoplastic starch biopolymer and regular mixed industrial sawdust of Iranian wood species including rush, walnut and hornbeam. To this aim, nanoparticles at 0, 3, and 5 wt% were added to the prepared biodegradable composites. Mechanical, thermal, water absorption and thickness swelling tests were performed according to their corresponding standards. In addition, to investigate the effects of working temperature on derived characteristics of the resulting composites, the selected mechanical tests were performed at various temperatures ranging from 23 to 80 °C. For validation of the results obtained from the physical tests, scanning electron microscopy was also utilized to examine the morphologies of the nanocomposites. The results showed that adding nanoparticles improved tensile modulus by 50%, tensile strength by 110%, flexural modulus by 115%, and flexural strength by 18%. Adding 5 wt% nanocellulose fibers showed better results than 3 wt% addition, while in the case of nanoclay, the trend was reverse. No significant change was observed for impact strength. Glass transition temperature was increased from 90 to 123 °C depending on the amount of nanoparticles. Water absorption and thickness swelling were reduced by around 20%. It was also observed that at elevated temperatures nanoparticles led to greater stability of the composite structure. From the results of this study it can be concluded that cellulose nanofibers and nanoclay particles can be successfully used for improving the mechanical and physical characteristics and performance of the biodegradable WPCs made of thermoplastic starch and industrial sawdust. Furthermore, since the effect of adding each of these nanoparticles on mechanical and physical performance of WPCs is different, the results of this study can be used to decide on selection of the type and amount of nanoparticles for fabrication of a product for a desired application.

The Effect of Resin-Coated Proppant and Proppant Production on Convergent-Flow Skin in Horizontal Wells With Transverse Fractures

Summary In the last decade, many gas reservoirs with permeabilities from 0.1 to 10 md have been developed with horizontal wells with transverse fractures. The potential negative effect of convergent flow in the fractures seems to have been forgotten. The widespread use of resin-coated proppant (RCP) in offshore wells appears to make this problem worse. Using both case studies and reservoir simulations, we examine why RCP could make the problem of convergent flow worse compared with uncoated proppant. Several North Sea horizontal and deviated multifracture gas wells that used RCP and had a significant mechanical skin are presented. Pressure-buildup data confirm the presence of a near-wellbore pressure drop in the fractures. Reservoir simulation with a fine grid reproduces the observed pressure drop because of convergent flow, using realistic proppant-pack permeabilities with gel damage. The effect of proppant production on the convergent-flow skin is shown using production data before and after discrete proppant-production events, demonstrating how proppant production has a beneficial effect on removing convergent-flow skin. We also compare the performance of a new horizontal multifracture well to the original discovery well in the same location, in which a vertical well was fracture stimulated with uncoated proppant and had comparable productivity. If there is a large convergent-flow skin in a fracture with uncoated proppant, this usually leads to some proppant production, which could create “infinite conductivity” channels at the perforations. This removes the convergent-flow pressure drop. If RCP is used to prevent proppant flowback, such channels cannot form easily, and convergent flow acts as a downhole “choke” on production. This “choke” can produce a significant positive skin. In the worst case, a horizontal multifracture well with three or four transverse fractures can produce the same as a fully perforated vertical well with a single fracture. On the basis of a number of real-world incidents of proppant production during post-fracture cleanup, we show strong evidence that a small amount of proppant production can result in an increase in well productivity index (PI) and a decrease in apparent fracture skin. Convergent flow is the most likely mechanism to explain this. In this paper we highlight the potential reduction in well productivity from using RCP for fracturing in gas wells (0.1 to 10 md) with limited inflow area (transverse or oblique fractures), where convergent-flow pressure loss is significant. We show the potential positive effect of small amounts of proppant production in such cases, forming infinite-conductivity channels and removing the convergent-flow skin.

Enhanced magneto-caloric effect upon fourth element (Cu, Fe, Co) substitution in Ni–Mn–Sn thin films

The effect of small amounts of fourth element X (Cu, Fe, Co) substitution on magnetic transition and magneto-caloric properties of Ni–Mn–Sn thin films has been investigated. The ternary and quaternary films show cubic L21 structure with room-temperature ferromagnetism after heat treatment. The Curie temperature of the film is close to room temperature which does not shift much upon X (Cu, Fe, Co) substitution. The variations in magnetic entropy change (ΔSM) and refrigeration capacity (RC) with Cu/Co substitution are very less. However, an enhancement in ΔSM and RC from − 3.85 × 104 erg/cc K (− 0.47 J/kg K) and 1.50 × 106 erg/cc (18.3 J/kg) to − 5.66 × 104 erg/cc K (− 0.69 J/kg K) and 2.50 × 106 erg/cc (30.4 J/kg) is observed with 3.6 at.% Fe substitution for a field change of 18 kOe. This shows that Fe is the ideal fourth element for enhancing magneto-caloric effect in Ni–Mn–Sn thin films.

Effect of Small Amount of Rare Earth Element Ce on the Mechanical Properties of Medium Carbon Microalloyed Steel

With the development of rare earth streated steel, the application and theory research of rare earth element in microalloyed steels are becoming more deeply and widely. So far, many investigations have been made on the effect of rare earth element on low carbon microalloyed steel. However, the effect of rare earth element on medium carbon microalloyed steel have not been clarified yet. In this work，the effect of small amount of rare earth element Ce on mechanical properties of medium carbon microalloyed steel were investigated by SEM, EDS and EBSD. The results show that the addition of rare earth elements can improve the comprehensive mechanical properties of medium carbon microalloyed steel, the strength-ductility balance increases from 23.57GPa% to 27.49 GPa%. In particular, the plasticity and toughness are improved obviously. The elongation rate and the impact toughness are increased by 14.8% and 19.5%, respectively. The rare earth elements did not markedly refine grain size and change matrix structure. However, the addition of rare earths increased the proportion of high-angle grain boundary from 33.2% to 40.2%. In addition, the fracture analysis with scanning electron microscopethe show that rare earth can make the inclusions denatured and hence spherical grain with small size can be obtained. The EDS result shows that rare earth and harmful elements P and O can cause inclusion, which purifies the molten steel and hinders the formation of microalloy element inclusions.

Effects of resolution in real and reciprocal spaces from a 2D detector at a high-energy synchrotron beamline

Different experimental conditions at a versatile high-energy beamline equipped with a two-dimensional detector have been compared for powder diffraction and pair distribution function (PDF) experiments. In particular, sample size and sample to detector distances have been evaluated on a standard sample, to evaluate their effects in both Q and real space. Two illustrative cases are also discussed. The average structure and local distortions in a BaTiO3 powder with 100 nm particle size show that spurious ripples in the PDF are suppressed by increased counting statistics. Effects of small amounts of a crystalline impurity phase on a SiO2.Al2O3.Na2O.CaO glass have been quantified.

Improvement of pork characteristics under commercial conditions with small amount of straw or hay

ABSTRACTThe objective of this study was to evaluate the effect of small amount of straw or hay (100 g/animal/day) and gender on pork characteristics, measured on slaughter line in longissimus dorsi et lumborum (LD) and semimembranosus (SM) muscles. We performed two replicates, each including 96 fattening pigs (half gilts and half barrows) reared under commercial conditions. Treatment had no effect on carcass characteristics and pH45 in both muscles. The straw and hay treatments lowered pH24 in LD muscle (straw: 5.71, hay: 5.74, control: 5.85), while hay treatment increased Fibre Optic Probe value (FOP24) in SM muscle compared to straw treatment (hay: 33.15, straw: 29.26). Gender had no effect on meat characteristics, but the interaction between treatment and gender revealed differences in FOP24 in SM muscle in gilts but not in barrows. Based on pH24 in LD muscle, straw treatment lowered percentage of pigs with DFD meat (straw: 6.2%, control: 28.6%), whereas based on FOP24 in SM muscle, hay treatment lowered percentage of pigs with DFD meat (hay: 9.4%, straw: 32.8%; control: 27.0%). We conclude that a small amount of straw or hay has a beneficial effect on meat quality as it lowered the incidence of DFD meat.

Nucleator Function of Glass Powders Used as Additives for Portland Cement

The effect of small amounts of glass powder on the technological properties of portland cement and, especially on the hardening process, is studied.

High rate capability and cyclic stability of hierarchically porous Tin oxide (IV)\u2013carbon nanofibers as anode in lithium ion batteries

Tin oxide–carbon composite porous nanofibres exhibiting superior electrochemical performance as lithium ion battery (LIB) anode have been prepared using electrospinning technique. Surface morphology and structural characterizations of the composite material is carried out by techniques such as XRD, FESEM, HR-TEM, XPS, TGA and Raman spectroscopy. FESEM and TEM studies reveal that nanofibers have a uniform diameter of 150–180 nm and contain highly porous outer wall. The carbon content is limited to ~10% in the nanofibers as shown by the TGA and EDAX which does not fade the high capacity of SnO2. These nanofibers delivered a higher discharge capacity of 722 mAh/g even after 100 cycles at high rate of 1C. The excellent electrochemical performance can be ascribed to the synergy effect of small amount of carbon in the composite and the hierarchically porous structure which accommodate large volume changes associated with Li-ion insertion–desertion. The porous nano-architecture would also provide a short diffusion path for Li+ ions in addition to facilitating high flux of electrolyte percolation through micropores. The electrochemical performance of composite material has also been tested at 60 °C at a higher rate of 2C and 5C. Post cycling FESEM analysis shows no volumetric and morphology changes in porous nanofibers after completing rate capability at high rate of 10C.

Flat-Top Cylinder Indenter Examination of Duplex Stainless Steel 2205 after Different Heat Treatments

The duplex stainless steel 2205 was heat treated at 750 °C, 850 °C, and 900 °C for increasing durations of up to 10 h. The samples were investigated through light microscopy (LM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) to characterize the volume fraction and morphology of the precipitated secondary phases. The samples were then tested via flat-top cylinder indenter for mechanical characterization (FIMEC) testing to determine the yield stresses that were found to be significantly affected by the different heat treatments. The yield stress evolution with heat treatments resulted in being correlated to both the relative volumes of the secondary phases and the morphology of the σ phase. The FIMEC test proved to be capable of detecting the effects of small amounts of secondary phases on yield stress in DSS 2205 and seems to be a promising technique for industrial applications.

Textural and optical studies of magneto-mesogen material for display applications

ABSTRACTIn this work, a magneto-mesogen material has been prepared by nematic liquid crystal (6OCB) and magnetic nanoparticles (Fe). The effect of small amount of Fe doping on textural behaviour and optical responses has been investigated in a planar aligned cell in the nematic phase. The doped sample shows relatively higher transmission intensity than pure 6OCB and decreases a threshold voltage from 1.4 V to 1.0 V. The UV-Vis spectra show that after dispersion the absorbance peak shift from 319 nm to 315 nm. The measured band gap in 6OCB and Fe-6OCB composite was found 3.71 eV and 3.72 eV respectively.

A Comparative Study of the Initial Corrosion of KCl and PbCl2 on a Low-Alloyed Steel

Heat exchange surfaces in biomass- and waste-fired boilers are exposed to corrosive species due to the considerable amounts of alkali chlorides and PbCl2 which are released during combustion. The corrosivity of alkali chlorides toward superheater alloys exposed at high temperature has been studied extensively. However, at lower material temperatures, i.e., at waterwall conditions, considerably less research has been performed. In order to investigate the effect of small amounts of KCl and PbCl2 during the initial stages of the corrosion attack, a Fe–2.25Cr–1Mo steel was exposed for 24 h in an atmospheres consisting of O2 + H2O + N2 at 400 °C. Both KCl and PbCl2 resulted in an increased corrosion rate compared to the reference. The aim of the present paper is to investigate the influence of KCl and PbCl2 on the initial oxidation of a Fe–2.25Cr–1Mo steel. The work involves a detailed microstructural investigation as well as thermodynamic equilibrium calculations.

Effectiveness of a small cash incentive on abstinence and use of cessation aids for adult smokers: A randomized controlled trial

BackgroundLarge amount of financial incentive was effective to increase tobacco abstinence, but the effect of small amount is unknown. PurposeWe evaluated if a small amount of cash incentive (HK$500/US$64) increased abstinence, quit attempt, and use of cessation aids. MethodsA three-armed, block randomized controlled trial recruited 1143 adult daily smokers who participated in the Hong Kong “Quit to Win” Contest. Biochemically validated quitters of the early-informed (n=379, notified about the incentive at 1-week and 1-month follow-up) and the late-informed incentive group (n=385, notified at 3-month follow-up) received the incentive at 3months. The validated quitters of the control group (n=379) received the incentive at 6months without prior notification. All subjects received brief advice, a self-help education card and a 12-page booklet. The outcomes were self-reported 7-day point prevalence of abstinence, quit attempt (intentional abstinence for at least 24h) and use of cessation aids at 3-month follow-up. ResultsBy intention-to-treat, the early-informed group at 3-month follow-up reported a higher rate of quit attempt (no smoking for at least 24h) than the other 2 groups (44.1% vs. 37.4%, Odds ratio (OR)=1.32, 95% CI 1.03–1.69, p=0.03), but they had similar abstinence (9.2% vs. 9.7%, OR=0.95, 95% CI 0.62, 1.45). The early- and late-informed group showed similar quitting outcomes. The early-informed group reported more quit attempts by reading self-help materials than the other 2 groups (31.4% vs. 25.3%, OR=1.56, 95% CI 1.12–2.18, p<0.01). ConclusionsThe small cash incentive with early notification increased quit attempt by “self-directed help” but not abstinence. Future financial incentive-based programmes with a larger incentive, accessible quitting resources and encouragement of using existing smoking cessation services are needed.

Effect of small quantity of chromium on the electrical, magnetic and magnetocaloric properties of Pr0.7Ca0.3Mn0.98Cr0.02O3 manganite

Structural, electrical and thermomagnetic properties of Pr0.7Ca0.3Mn0.98Cr0.02O3 were investigated. Sample was prepared by solid-state reaction method. X-ray diffraction revealed that the sample crystallizes in the orthorhombic system with Pnma space group. Electrical conductivity and complex impedance studies of Pr0.7Ca0.3Mn0.98Cr0.02O3 system are analyzed. The investigated compound exhibits a semiconductor behavior in the whole explored temperature range. From 100 to 206 K, the increase in DC conductance is more than two decade. At higher temperatures, the conductance varies slowly and a saturation region appears. The conduction mechanism is found to be governed by small polaron hopping process which is explained by the short range thermally activated energy. Conductance spectrum is well described by Jonsher law, and the temperature dependence of the frequency exponent confirms that conduction mechanism is governed by hopping process of the localized carriers. Using complex impedance analysis, the compound is modeled by an electrical equivalent circuit. Also, such analysis confirms the contribution of grain boundary to the transport properties. The substitution of Mn by 2 % Cr destroyed the charge order state observed in the parent compound and induced a ferromagnetic phase at low temperatures. For a magnetic field change of 5 T, the material shows a maximum magnetic entropy change |∆S max| = 2.69 J kg−1 K−1 with a full width at half maximum δ TFWHM = 145 K, and a relative cooling power RCP = 389 J kg−1. Pr0.7Ca0.3Mn0.98Cr0.02O3 material demonstrates potential proprieties to be used in electronic and thermal devices and as magnetic refrigerant.

Effect of the Al–Zr–Y master alloy composition on the modifying effect in the Al–4% Cu alloy

The results of modifying the Al–4% Cu alloy with test Al–1.04% Zr–0.70% Y and Al–1.23% Zr–0.39% Y master alloys are reported; the Zr-to-Y atomic-percentage ratio in the alloys is 1.41 and 3.08, respectively. The effect of small amounts of Zr and Y (from 0.1 to 0.3%) added in the form of test ternary master alloys of different compositions and binary Al–Zr and Al–Y master alloys on the grain refinement in the Al–4% Cu alloy has been studied. The structure of the initial alloy is characterized by pronounced directional solidification of the α phase. As the Zr + Y content increases, the columnar-crystal zone decreases and the equiaxed-crystal zone increases; at a (Zr + Y) content of 0.326%, only equiaxed crystals ~200 μm in size are present in an ingot. When Zr and Y are added with binary master alloys, the macrostructure of the modified Al–4% Cu alloys indicates that columnar crystals grow until their contact at the center of the ingot, and their growth is independent of the amount of added Zr and Y.

Effect of small amounts of metal/carbon nanocomposites on the properties of polymer materials

Metal/carbon nanocomposites have been studied by electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS). EPR study has revealed the existence of delocalized electrons on the carbon shells and the presence of reduced paramagnetic states of nickel in the nickel/carbon nanocomposite. XPS has detected the change in the atomic magnetic moment of the metal. For polycarbonate as an example, conditions for modification of the polymer composition with small amounts of metal/carbon nanoparticles (0.01–0.0001%) have been determined. On the basis of the data obtained, a mechanism of the effect of metal/carbon nanoparticles on the structure and properties of polymer materials has been suggested.