Influence of the hydrophilic–lipophilic balance of sunscreen emulsions on their water resistance property

The use of sunscreens with sun protective cloths is the photoprotection way mostly used by Occidentals. During sweating or a bath, those products should be still efficient. As the emulsion is the mostly used type of product format, it is essential that the scientist knows how to formulate an emulsion which will be water resistant. The HLB (hydrophilic–lipophilic balance) of a formulation has high influence on this characteristic.     

Evaluation of asphalt–aggregate interaction based on the rheological properties

The silicon dioxide (SiO₂) and calcium oxide (CaO) analytical reagents are selected to prepare asphalt mastics and the effects of aggregate chemical composition on asphalt–aggregate interactions (AAI) are evaluated based on the complex modulus and phase angle. It is found that the oxide analytical reagents significantly affect the rheological properties such as complex shear modulus and phase angle, and the effects of CaO are greater than SiO₂ due to the stronger interaction between asphalt binder and CaO analytical reagents. Both the modulus stiffening ratio and the phase angle-based K. Ziegel-B coefficient could be used to evaluate the AAI, and the latter is the better index. Results show that the indexes increase with the test temperature, but decrease with the loading frequency, and tend to be constant. The higher adhesive strength between asphalt binder and limestone than basalt is likely attributed to the higher content of CaO in limestone aggregate and the stronger asphalt–CaO interaction.     

Kinetics of the Photocurrent of a UV Sensor Based on Indium–Zinc Oxide Nanowires

Technical Physics Letters - An analysis of the experiments on the kinetics of the rise and decay of the current under the influence of extreme ultraviolet radiation on the indium–zinc oxide...     

Analysis on the removal mechanism of disc grinding based on dynamic thermal–mechanical coupling

International Journal of Mechanics and Materials in Design - Disc grinding is a commonly-utilized removal technology to generate the machining surface with higher precision. The material removal is...     

The effect of matrix polarity on the properties of poly(o-methoxyaniline)–EVA blends

Poly(o-methoxyaniline) (POMA) doped with p-toluene sulfonic acid (TSA) was successfully melt blended with ethylene vinyl acetate copolymer (EVA). The effect of the matrix polarity as well as the blend composition on the properties of the blends was investigated using two grades of EVA as matrix. The lower polarity EVA contains 8% vinyl acetate (VA) (EVA₈) and the higher polarity EVA contains 33% VA (EVA₃₃). The surface resistivity of the POMA-EVA blends was found to decrease with an increase of POMA loading. The POMA-EVA₈ blends had a lower surface resistivity than POMA-EVA₃₃ blends which is attributed to the presence of a higher proportion of conductive POMA particles in the surface region resulting from the larger polarity difference between the POMA and the EVA₈ matrix. More uniform dispersion is observed from scanning electron microscopy (energy-dispersive X-ray spectroscopy) for POMA in EVA₃₃ compared to POMA in EVA₈ and this has been interpreted as being a consequence of the similar polarities between POMA and EVA₃₃. The mechanical properties of the blends were found to be affected by both POMA loading and matrix polarity. The oxygen barrier property of the POMA-EVA blends was found to increase with POMA loading in both high and low polarity EVA matrices.     

Evolution of the microstructure and phase composition of materials based on the fluorohydroxyapatite–zirconia–alumina system during sintering

We have studied the influence of the sintering temperature, Al₂O₃ additions, and liquid-forming sintering aids on the phase composition and microstructure of fluorohydroxyapatite-based composite ceramic materials containing 20 and 60% zirconia. The addition of alumina has been shown to prevent secondary recrystallization processes during sintering and contribute to stabilization of tetragonal zirconia. The addition of the sintering aid has made it possible to lower the sintering temperature to 1200°C.     

Micro–macro homogenization of granular materials based on the average-field theory of Cosserat continuum

This paper performs further study on the micro–macro homogenization approach of granular materials (Li et al., 2010) based on the advancement of Hill’s lemma for Cosserat continuum (Liu, 2013). Firstly, the average couple stress tensor, expressed as the volume integration of quantities over the representative volume element (RVE) in the average-field theory of Cosserat continuum, is further deduced and expressed in terms of discrete quantities on the discrete particle assembly RVE of granular materials. The expression is also discussed and compared with other typical definitions of the effective couple stress tensor for granular materials in the literature. Then, rate forms of micromechanically based constitutive models consistent with different types of RVE boundary conditions are derived and discussed. Since the presented micro–macro homogenization approach is used, not only the micro–macro energy equivalence is satisfied, but also the microstructure and its evolution can be taken into account in the constitutive formulation with no need of specifying macroscopic phenomenological constitutive model.     

The effect of thermal fatigue on the mechanical properties of the novel fiber metal laminates based on aluminum–lithium alloy

The effect of thermal fatigue on the mechanical properties of the novel fiber metal laminates (FMLs) based on aluminum–lithium alloy was investigated. The results indicated that no obvious delamination or defects were observed in the novel FMLs exposed to 1000 cycles. The samples treated with different cycles still exhibited stable and excellent interlaminar properties comparing with the as-manufactured ones. Furthermore, the tensile and flexural strength of the FMLs even increased with the thermal fatigue cycles owing to the positive age hardening behavior of aluminum–lithium layer. The homogeneous and fine precipitation of T₁ phases dominated the strengthening effect of aluminum–lithium alloy. Besides, the novel FMLs after thermal fatigue treatments still possessed the similar resistance to fatigue crack growth (FCG) when compared with the as-manufactured ones. The slight changes in the properties of aluminum–lithium layers had no detrimental effect on the FCG.     

Effect of the rate of cooling tungsten heavy alloys of the W–Ni–Fe type from the sintering temperature on the formation of their physico-mechanical properties

The effect of the conditions of cooling after the liquid-phase sintering of tungsten heavy metals have been studied. It has been found that to attain a high ductility of the tungsten heavy metal, the rate of cooling from the sintering temperature should afford removal of the major part of hydrogen, which was dissolved in the alloy volume in the temperature range of the liquid phase existence.     

Mechanical properties of Sn–Zn lead-free solder alloys based on the microstructure array

The aim of this study is to develop a comparative experimental study interrelating mechanical properties, solidification thermal parameters and microstructure characteristics of a hypoeutectic Sn–4 wt.% Zn, a hypereutectic Sn–12 wt.% Zn and a eutectic Sn–9 wt.% Zn solder alloys. A water-cooled vertical upward unidirectional solidification system was used to obtain the samples. It was found that a more homogeneous distribution of the eutectic mixture, which occurs for smaller dendritic spacings in hypoeutectic and hypereutectic alloys, increases the ultimate tensile strength. The resulting microstructure of the eutectic Sn-9 wt.% Zn alloy has induced higher mechanical strength than those of the Sn–4 wt.% Zn and Sn–12 wt.% Zn alloys. It was found that the eutectic alloy experiences a microstructural transition from globular-to-needle-like Zn-rich morphologies which depend on the solidification growth rate. It is also shown that a globular-like Zn-rich morphology provides higher ultimate tensile strength than a needle-like Zn-rich eutectic morphology.     

A comparison of three multidisciplinarity indices based on the diversity of Scopus subject areas of authors’ documents,their bibliography and their citing papers

Scientometrics - In this paper, we compare the distribution of Elsevier Scopus subject areas of authors’ documents, their bibliographical references and their citing documents. We compute the...     

Electrosynthesis of pinecone-shaped Pt–Pb nanostructures based on the application in glucose detection

The pinecone-shaped Pt–Pb nanostructures were synthesized by electrochemical deposition. The morphology and composition of the pinecone-shaped Pt–Pb nanostructures were characterized by scanning electron microscopy, energy dispersive X-ray detector, transmission electron microscopy and X-ray photoelectron spectroscopy. Cyclic voltammetry and differential pulse voltammetry were used to evaluate the electrocatalytic performance of the pinecone-shaped Pt–Pb nanostructures electrode toward glucose oxidation in neutral media. As a result, the pinecone-shaped Pt–Pb nanostructures electrode exhibited strong current responses to glucose at a negative potential of ? 0.1 V, where the interference from the oxidation of ascorbic acid was effectively avoided. The sensitivity of the sensor was 10.71 μA mM^?1 cm^?2 with a linearity up to 12 mM and a detection limit of 8.4 μM. In addition, the as-prepared nonenzyme glucose sensor exhibited acceptable stability and reproducibility for determination of glucose. The simple preparation method and good analytical performance can potentially pave the way for effective and highly sensitive non-enzyme glucose sensors.     

Effect of the surface chemical groups of activated carbons on their surface adsorptivity to aromatic adsorbates based on π-π interactions

Three activated carbons with different surface chemical groups were used to analyse the influence of these groups on their adsorption capacities towards aromatic-type molecules whose adsorption is based on π-π interactions with surface arene centres. The three activated carbons studied were a low-functionalized carbon (Merck), an oxygen-rich carbon obtained by HNO₃ oxidation of Merck, and a nitrogen-rich carbon also prepared from Merck by mild HNO₃ oxidation followed by treatment with a dicyanodiamide/dimethyl formamide mixture at 300 °C. The nature of the surface chemical groups of the three activated carbons was investigated by both physical and chemical techniques (TPD, XPS, Boehm analysis and pH potentiometric titration). A systematic study of the adsorptions of a series of analogous aromatic adsorbates on the three activated carbons was carried out to study the adsorption mechanisms. In all cases the adsorption mechanism is based on π-π interactions between the aromatic moiety of the adsorbates and the arene centres of the graphite sheets. The differences in the normalized adsorption capacities of the adsorbents for a set of adsorbates indicate that the π-donor or π-withdrawing character of the functional groups have a clear influence on the basicity of the arene centres.     

Toughening of polyamide 6 with β-nucleated thermoplastic vulcanizates based on polypropylene/ethylene–propylene–diene rubber grafted with maleic anhydride blends

The toughening of polyamide 6 (PA 6) with β-nucleated thermoplastic vulcanizates (TPVs) based on polypropylene (PP)/ethylene–propylene–diene rubber grafted with maleic anhydride (EPDM-g-MAH) blends was studied. A series of TPVs without and with different dosage of β-nucleating agent (β-NA) were prepared and used to toughen PA 6 at the same proportion. Differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) measurements showed that β crystals of PP were effectively induced in the TPVs. The PA 6 blends toughened with β-nucleated TPVs (β-TPVs) exhibit significantly enhanced toughness, balanced mechanical properties and thermal properties compared with PA 6 toughened by TPV without β-NA or only by EPDM-g-MAH. Phase morphologies of the blends characterized by scanning electron microscopy (SEM) showed that better interfacial adhesion caused by the migration of β-NA from PP to PA 6/PP interface and PP/EPDM-g-MAH interface gives rise to more uniform dispersion and smaller size of the dispersed phase; moreover, the core–shell structure comprised of rubber particles enveloped by PP on the surface, brings about easier and stronger interference of the stress field of EPDM phase.     

Study on the effect of exhaust gas-based fuel preheating device on ethanol–diesel blends operation in a compression ignition engine

Rapid depletion of fossil fuels and stringent emission regulations compel the scientific community to search for alternative energy sources for the internal combustion engines. Among many alternative biofuels, ethanol is getting worldwide attention for compression ignition engine either in the form of partial substitute or complete replacement for diesel fuel. Ethanol fuel has certain undesirable properties like poor flammability limit which results in cold starting issues and higher hydrocarbon emission which restricts their use in compression ignition engine. This issue can be easily overcome by preheating of ethanol fuel before it gets admitted inside the engine cylinder. In the present study, a standard preheating device is designed and fabricated in accordance with engine specifications and simulations were carried out under various operating conditions to evaluate its performance. Furthermore, experimental investigations were carried out in a compression ignition engine fueled with ethanol blends of 20 and 30% with diesel by volume and the fuel blends were preheated using burned exhaust gases. In addition, a comparative study has been carried out for preheated and non-preheated blends of E20 (20% of ethanol and 80% of diesel) and E30 with baseline diesel. The experimental results show that the preheated E20 (20% of ethanol and 80% of diesel) blend has higher brake thermal efficiency of 36.28% with a significant reduction in brake specific fuel consumption when compared with all the other blends. Moreover, the preheated E20 blend reduces the carbon monoxide, unburned hydrocarbon and smoke emissions by 49, 48 and 10%, respectively. However, the NOx emission is increased by 6% as compared to the non-preheating effect. It is also noted that the preheating of ethanol blends produced better combustion results with a significant reduction in the ignition delay period. Hence, it can be concluded that the ethanol fuel can be effectively used in a diesel engine by means of preheating using exhaust gases and could be a viable option for diesel engine applications.     

Effects of virgin Ethylene–Propylene–Diene–Monomer and its preheating time on the properties of natural rubber/recycled Ethylene–Propylene–Diene–Monomer blends

Blending of natural rubber/recycled Ethylene–Propylene–Diene–Monomer (NR/R-EPDM) blends was carried out. A fixed amount of carbon black and virgin Ethylene–Propylene–Diene–Monomer (EPDM) were also introduced into the blends. Applications of two different processing methods were carried out to improve the cure compatibility, crosslink distribution, and hence mechanical properties of the blends. Simple processing method was done by mixing the entire additives and rubbers on a laboratory-sized two-roll-mill at ambient temperature. Whereas, reactive processing method was conducted by mixing virgin EPDM, recycled EPDM and other compounding ingredients using an internal mixer, the compound was later preheated according to designated time before blending with natural rubber and carbon black. Results revealed that the enhancement of the physical and mechanical properties was significantly achieved towards preheating time of EPDM/R-EPDM blends. The improved properties in the blends suggested that the reactive processing method had led to more homogeneous blends due to a better crosslink distribution and more homogeneous carbon black distribution.     

Investigation of novel polyurethane elastomeric networks based on polybutadiene-ol/polypropyleneoxide mixture and their structure–properties relationship

Polyurethane elastomer networks were designed and synthesized based on hydroxyl terminated polybutadiene/polypropyleneoxide (HTPB/PPO) mixtures, 2,4-toluene diisocyanate and 1,4-butanediol. Various networks with different molar ratio of HTPB to PPO (0/100, 25/75, 50/50, 75/25 and 100/0) had been prepared. Depending on the length of soft segment, average functionality of polyol mixtures, mechanical and thermal properties of samples were varied. Our observations confirmed that final properties of the networks can be attributed to two synergistic factors: (a) formation of chemical network (crosslinking) and (b) soft segment length. An optimum composition was found. This optimum composition shows that both physical (hard domains) and chemical network (crosslinking) have synergistic effects. Moreover, Flory–Hugins interaction parameters of soft and hard segments were calculated. Synthesized polyurethane elastomer networks have a structure similar to semi interpenetrating polymer networks, which is named pseudo-semi-IPN. These novel polyurethane elastomer networks show higher tensile strength and economic benefit than polyurethanes which are based on other non-polar polyols.