Impinging blood droplets on different wettable surfaces: Impact phenomena, contact line motion, post-impact oscillation and dried stains.

Understanding the underlying hydrodynamics of impinging blood droplets and finding out the physical parameters determining the bloodstain characteristics are of great importance in blood related forensic investigations. In this work, the impact of non-Newtonian blood droplets on solid surfaces ranging from lyophilic to superlyophobic was systematically investigated and compared to that of Newtonian droplets with a similar dynamic shear viscosity. We show that impinging blood droplets behave as low-viscosity Newtonian droplets in the short-time spreading, which is dominated by capillary and inertial forces, but their non-Newtonian viscoelasticity would notably affect the droplet retraction and post-impact oscillation occurring in large timescales. Whereas the strong liquid-solid adhesion and the non-Newtonian elongational viscosity hinder droplet recoiling and thus alter the impact phenomena on lyophobic and superlyophobic surfaces, the shear and elongational viscosities are coupled to result in higher damping coefficients of oscillating blood droplets after deposition, in comparison to that of impinging Newtonian droplets. The size of the dried bloodstain was found to be different from both the maximum spreading radius of the droplet that can reach during impact and the final radius of the deposited droplet after oscillation, and their correlations are highly dependent on the impact velocity and surface wettability. Moreover, the morphologic characteristics of the bloodstains would also be changed by varying either the impact velocity or the surface wettability. We envision that these findings can not only find applications in the bloodstain pattern analysis, but also provide useful information for medical diagnosis based on blood droplet test.

Regularized robust estimation in binary regression models.

In this paper, we investigate robust parameter estimation and variable selection for binary regression models with grouped data. We investigate estimation procedures based on the minimum-distance approach. In particular, we employ minimum Hellinger and minimum symmetric chi-squared distances criteria and propose regularized minimum-distance estimators. These estimators appear to possess a certain degree of automatic robustness against model misspecification and/or for potential outliers. We show that the proposed non-penalized and penalized minimum-distance estimators are efficient under the model and simultaneously have excellent robustness properties. We study their asymptotic properties such as consistency, asymptotic normality and oracle properties. Using Monte Carlo studies, we examine the small-sample and robustness properties of the proposed estimators and compare them with traditional likelihood estimators. We also study two real-data applications to illustrate our methods. The numerical studies indicate the satisfactory finite-sample performance of our procedures.

Preparation of Iron Ore Tailings-Based Superhydrophobic Coatings.

In this study, ball mill pretreated iron ore tailings were modified with tetraethoxysilane (TEOS) and hexadecyltrimethoxysilane (HDTMS) to obtain iron ore tailings/polysiloxane (IOT/POS) superhydrophobic powders, which were subsequently mixed with chloroprene rubber solution (CRS) to prepare durable superhydrophobic composite coatings. The effect of HDTMS amount and reaction time on the wettability of the superhydrophobic powder was investigated. The influence of the superhydrophobic powders concentration on the wettability of the composite coatings as well as the degree of damage of the superhydrophobicity of the composite coating was analyzed by using the sandpaper abrasion and tape peeling tests. Further, SEM and FTIR were used to analyze the formation mechanism of the IOT/POS superhydrophobic powders and coatings. The results showed for an HDTMS amount of 2.5 mmol and reaction time of 4 h, the contact angle of the IOT/POS powder was 157.3 ± 0.6°, whereas the slide angle was determined to be 5.9 ± 0.8°. For an IOT/POS powder content of 0.06 g/mL in CRS, the contact angle value of the superhydrophobic composite coating was 159.2 ± 0.5°, whereas the slide angle value was 5.5 ± 0.8°. The superhydrophobic composite coating still maintained the superhydrophobicity after the sandpaper abrasion and tape peeling tests, which indicated the iron ore tailings solid waste has the potential to prepare superhydrophobic coatings.

Ultrafine Grinded and Silane Grafted Iron Ore Tailings as Reinforcing Filler of Styrene Butadiene Rubber.

In order to realize the high value-added resource utilization of solid waste and reduce the cost of rubber manufacturing, iron ore tailings (IOTs) were used as raw material to prepare a reinforcing filler of rubber through ultrafine grinding and surface organic modification techniques. We studied the effects of ball mill grinding conditions on the particle size and distribution of grinded iron ore tailings (G-IOTs). The effects of bis-(triethoxy-silyl-propyl)-tetrasulfide (Si69)-modified G-IOT (Si69-G-IOT) loading levels on the cure characteristics, static mechanical and dynamic mechanical properties of the styrene butadiene rubber (SBR) composites were also explored in this paper. The grinding and modification mechanism of IOTs and the combination of filler and SBR matrix were explored by grinding simulation of population balance model, X-ray diffraction analysis, Fourier transform infrared spectroscopy and scanning electron microscopy. The results showed that when grinding IOTs at 2000 r/min for 150 min, the particle size distribution of the resulting G-IOTs was the narrowest, with a D90 value of 4.42 µm. The tensile strength and elongation at break of SBR filled with 120 phr Si69-G-IOT were 14.97 MPa and 596.36%, respectively.

High emission reduction performance of a novel organic-inorganic composite filters containing sepiolite mineral nanofibers.

In this work, a new organic-inorganic composite filter was prepared. The thickness, pore size, air permeability, bursting strength and microstructure were characterized systematically, proving that coatings had regulatory effect on filters physical properties. Benefitting from the distinct coatings containing 5% sepiolite nanofibers after five times dilution, the physical properties of corresponding air filter exhibits the most favorable performance and meet the standard of air filter. When used as fuel filter, it satisfies the fuel filter standard and achieves the best performance after six times dilution. The contrast test on engine emission was taken based on auto filters coated with/without as prepared nanofibers. An obvious decrease in the emission of carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxide (NOx) can be observed after installation of composite filter on vehicles. Under the high idle condition, gasoline engine emission decreased by 8.13%, 11.35% and 44.91% for CO, HC and NOx, respectively. When tested in the low idle condition, engine emission reduced by 0.43%, 1.14% and 85.67% for CO, HC and NOx, respectively. The diesel engine emissions of CO, NOx and total amount of HC and NOx decreased by 32.26%, 3.28% and 4.66%, respectively. The results illustrate the composite installation exhibits satisfactory emission reduction effect.

The regulation of sepiolite surface free energy and its impact on the thermal insulation property of coating.

Surface modification is used to regulate surface free energy of sepiolite with 3-glycidoxypropyltrimethoxysilanes (3-GPTMS), 3-methacryloxypropyltrimethoxysilanes (3-MAPTMS) and 3-mercaptopropyltrimethoxysilane (3-MPTMS). Through characterization by Fourier transform infrared spectroscopy, surface free energy, zeta potential and sedimentation measurements and infrared emissivity, it is found that the surface free energy of 3-MPTMS modified sepiolite decreases to 31.72 mJ/m2 and the percentage of polar component increases to 89.75%, thus leading to that the infrared emissivity of 3-MPTMS modified sepiolite increase to be higher than 0.8 and the dispersion of sepiolite has been improved. The excellent thermal insulation property of coating is prepared with 10% additive amount of 3-MPTMS modified sepiolite and the temperature difference between upper and lower box of modified sepiolite coatings is 10 degrees C which is higher than the untreated sepiolite.

Cleanability evaluation of ceramic glazes with nanometer far-infrared materials using contact angle measurement.

The cleanability of easy-to-clean ceramic glazes doped with nanometer far-infrared materials was compared with that of some high-quality household ceramic glazes from the market. The cleanability was evaluated by the contact angle measurement using a sessile drop method with a Dataphysics OCA-30 contact angle analyzer. The results showed that the difference of contact angles of water on the glazes before soiling and after cleaning could be used as a parameter for evaluating the cleanability of the glazes. The relationship between cleanability and surface properties, such as surface free energy and surface topography, was investigated. The surface free energy of the samples and their components were calculated using van Oss acid-base approach. By measuring advancing and receding contact angles, the contact angle hysteresis of the ceramic glazes due to the surface topography was investigated. It was shown that the cleanability of ceramic glazes containing nanometer far-infrared materials (NFIM) is better than that of household ceramic glazes from market, due to a higher ratio of electron-acceptor parameter to electron-donor parameter, which led to the effect of water hydration as well as better hydrophilic property and increased smoothness. The contact angle measurement not only accurately evaluates the cleanability of the ceramic glazes, but also has a contribution to the study of cleanability theory. Moreover, this method is simple, convenient and less sample-consumption.

Preparation and performance of thermal insulation energy saving coating materials for exterior wall.

Nano zinc oxide with a high refractive index has good thermal reflection performance, hollow glass microspheres have good thermal reflection and insulation performance, and sepiolite nanofibers with many nanostructural pores have good thermal insulation performance. The dispensability of nano zinc oxide in coating materials was improved by optimizing surface silane coupling agent modification process, leading to the good thermal reflection performance. The thermal insulation performance was improved by hollow glass microspheres and sepiolite nanofibers. On this basis, the thermal insulation coating materials were prepared by exploring the effect of amount, complex mode, and other factors of the above three kinds of functional fillers on the thermal reflection and insulation performance of coating materials. The results showed that the surface modification effect of nano zinc oxide was the best when the silane coupling agent addition was 6%. The reflection and insulation performance of the coatings were the best when the additions of modified nano zinc oxide, hollow glass microspheres, and sepiolite nanofibers were 3%, 4%, and 4%, respectively. Compared with the control coating materials, the thermal insulation effect was improved obviously, which was evaluated by the -13.5 degrees C increase of maximum temperature difference between the upper and the lower surfaces.

Channel microstructure and thermal insulation mechanism of sepiolite mineral nanofibers.

The longitudinal and cross sectional TEM images of sepiolite mineral nanofibers were prepared by cutting in the direction parallel and perpendicular to nanofibers, and the channel microstructure of sepiolite nanofibers was studied. The thermal insulation mechanism of sepiolite nanofibers was analyzed according to the diagrammatic sketch obtained from the above experimental method. The results showed that many discontinuously connected bending shape channels with about 23-26 nm in diameter existed in the center region of nanofibers, and many discontinuously connected irregular micropores and mesopores with the size of about 1-9 nm existed on the wall of nanofibers. The main reasons for the formation of channel microstructure in sepiolite nanofibers were their minerogenetic conditions and the interaction between acid and high-speed airflow in the process of nanofibers preparation, and bubbles in the hydrotherm played a significant role in the microstructure formation. The thermal insulation performance of sepiolite nanofibers could be attributed to obstructive and infrared radiative thermal insulation.

Reinforcement of denture base PMMA with ZrO(2) nanotubes.

In the research described, ZrO2 nanotubes were prepared by anodization. The morphologies, crystal structure, etc. were characterised by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffractometer (XRD), and Fourier transform infrared spectroscopy (FTIR). ZrO2 nanotubes were pre-stirred with the denture base PMMA powder by a mechanical blender and mixed with MMA liquid to fabricate reinforced composites. The composites were tested by an electromechanical universal testing machine to study the influences of contents and surface-treatment effect on the reinforcement. The ZrO2 nanoparticles were also investigated for comparative purposes. Results indicated that ZrO2 nanotubes had a better reinforcement effect than ZrO2 nanoparticles, and surface-treatment would lower the reinforcement effect of the ZrO2 nanotubes which itself was significantly different from that of the ZrO2 nanoparticles. The flexural strength of the composite was maximised when 2.0wt% untreated ZrO2 nanotubes were added.

Preparation and far infrared emission properties of natural sepiolite nanofibers.

Sepiolite nanofibers were prepared by high-speed air current superfine technique, using natural sepiolite samples as raw materials. Through characterization by scanning electron microscope (SEM), X-ray diffraction (XRD), dynamic contact angle meter and tensiometer (DCAMT) and Fourier transform infrared spectroscope (FTIR), it was found that the defibered sepiolite nanofibers with an average diameter of about 100 nm and length greater than 9 microm had a better far infrared emitting performance than acid-purified sepiolite as the contrast sample, and the defibering treatment led to the improvement of far infrared emitting performance of sepiolite due to the increase of surface free energy, the increase of infrared active bond vibrations, and the decrease of cell volume caused by the distortion of structural channel.