Asymmetric Wettability Janus Mesh via Electrostatic Printing for Selective Oil-Water and Emulsion Separation.

Janus mesh with two-sided asymmetric wettability shows high potential for selective oil-water and emulsion separation. However, it remains a challenge to construct Janus mesh structures with good stability and extremely asymmetric wettability. Herein, a novel Janus mesh with asymmetric wettability was structured by two different precursors, polydimethylsiloxane/zinc oxide (PDMS/ZnO) and zinc oxide-polyacrylonitrile/N,N-dimethylformamide (ZnO-PAN/DMF), by electrostatic printing, including electrostatic air spraying and electrostatic spinning. The prepared Janus mesh has special micro-nanostructures on two sides, including PDMS@ZnO and ZnO@PAN. On the basis of gravity, when the placement direction is changed, Janus mesh can effectively separate oil-water mixtures of different densities and surfactant-stabilized oil-water emulsions. Meanwhile, the obtained Janus mesh exhibited good separation efficiency (>96.3%) for various oil-water mixtures, and the flux was up to 2621 ± 30 L m-2 h-1. The Janus mesh was cycled 20 times with no weakening in separation efficiency, indicating satisfactory cycling stability. The Janus mesh displayed good stability under harsh conditions (acidic, alkaline, and high temperature). The Janus mesh can realize low energy input and long-lasting oil-water separation, which has widespread application prospects in intelligent oil-water separation. This top-down electrostatic printing strategy provides a way to construct Janus interface materials with practical applications.

Multiscale Microflower Structured Superhydrophobic Surface via Electrostatic Air Spray.

Superhydrophobic surfaces with microstructures and multifunctionality have attracted intense research interest. Herein, a multiscale microflower structured surface (MMSS) was successfully fabricated by electrostatic air spray. To systematically study the preparation process, the influences of different electrostatic voltages, solution ratios, soaking time, spray distances, and spray time on surface morphology and hydrophobicity were analyzed. The surface has good superhydrophobic properties with a water contact angle of 162.3°, which allows the surface to be self-cleaning and antifouling. The surface hydrophobicity can be maintained after various mechanical and chemical damages. To overcome the limitation that existing droplet manipulation relies on special materials and surfaces, a new and universal droplet transport method is presented to successfully perform nondestructive droplet manipulations, which relies on external forces and droplet deformation to drive droplets. Therefore, this paper represents a different approach from previous studies of superhydrophobic surfaces and provides a new way to achieve dynamic droplet manipulations. These results indicate that the multifunctional MMSS will be widely used in industrial droplet transportation and self-cleaning applications.

Self-assembled micropillar arrays via near-field electrospinning.

Self-assembly in near-field electrospinning is reported for the first time in this paper, which realized the conversion from two-dimensional planar printing to three-dimensional (3D) structures. Repeatedly stacked fibres formed a micropillar array structure (MPAS) with intervals on the deposition paths by adding carbonyl iron powder particles to a polyethylene oxide (PEO) solution. The growth process of the self-assembled MPAS is documented, and the mechanism of the self-assembled MPAS is proposed. In addition, the effects of substrate speed and injection speed on self-assembly were investigated. Electric field distribution simulations show that the electric field strength around the MPAS is enhanced by nearly ten times so that the micropillar can attract the jet for further deposition. Self-assembly can obtain MPASs with arbitrary paths on different substrates, and the interval of the MPAS can be controlled by using bulging substrates. Furthermore, a self-assembled MPAS has been successfully used to prepare mold cavities, which can be used to prepare MPASs of other materials. Due to their small feature size, large surface area and structural periodicity, micropillar arrays will have promising applications, such as hydrophobicity of surfaces and electrochemical detection. Self-assembly in near-field electrospinning can significantly reduce the preparation cost of an MPAS and provide new processes and ideas.

Maturity Grading and Identification of Camellia oleifera Fruit Based on Unsupervised Image Clustering.

Maturity grading and identification of Camellia oleifera are prerequisites to determining proper harvest maturity windows and safeguarding the yield and quality of Camellia oil. One problem in Camellia oleifera production and research is the worldwide confusion regarding the grading and identification of Camellia oleifera fruit maturity. To solve this problem, a Camellia oleifera fruit maturity grading and identification model based on the unsupervised image clustering model DeepCluster has been developed in the current study. The proposed model includes the following two branches: a maturity grading branch and a maturity identification branch. The proposed model jointly learns the parameters of the maturity grading branch and maturity identification branch and used the maturity clustering assigned from the maturity grading branch as pseudo-labels to update the parameters of the maturity identification branch. The maturity grading experiment was conducted using a training set consisting of 160 Camellia oleifera fruit samples and 2628 Camellia oleifera fruit digital images collected using a smartphone. The proposed model for grading Camellia oleifera fruit samples and images in training set into the following three maturity levels: unripe (47 samples and 883 images), ripe (62 samples and 1005 images), and overripe (51 samples and 740 images). Results suggest that there was a significant difference among the maturity stages graded by the proposed method with respect to seed oil content, seed soluble protein content, seed soluble sugar content, seed starch content, dry seed weight, and moisture content. The maturity identification experiment was conducted using a testing set consisting of 160 Camellia oleifera fruit digital images (50 unripe, 60 ripe, and 50 overripe) collected using a smartphone. According to the results, the overall accuracy of maturity identification for Camellia oleifera fruit was 91.25%. Moreover, a Gradient-weighted Class Activation Mapping (Grad-CAM) visualization analysis reveals that the peel regions, crack regions, and seed regions were the critical regions for Camellia oleifera fruit maturity identification. Our results corroborate a maturity grading and identification application of unsupervised image clustering techniques and are supported by additional physical and quality properties of maturity. The current findings may facilitate the harvesting process of Camellia oleifera fruits, which is especially critical for the improvement of Camellia oil production and quality.

The Effects of Different Blood Sample Types on Quantitative Detection of Procalcitonin.

BACKGROUND: Procalcitonin (PCT) has been recommended and widely used for the prognosis, diagnosis, and monitoring of sepsis. Currently, a majority of PCT detection products are limited to using serum samples, which requires the tedious pre-treatment process, as well as a large sample volume for analysis. Hence, there is an increasing need to replace serum with plasma or whole blood samples. In this work, we evaluated the effects of different blood sample types on PCT quantitative detection by measuring PCT levels in clinically homogenous whole blood, plasma, and serum samples, in hope of extending the application of PCT detection in more sample types. METHODS: Ninety patients from Tong Ren Hospital of Shanghai Jiao Tong University, School of Medicine with different PCT levels volunteered for this study. Clinically homogenous samples, including EDTA- K2 anticoagulant whole blood, centrifuged serum and procoagulant plasma, were collected and analyzed using i-Reader S automatic immunoanalyzer and its supporting reagent kits. Passing and Bablok regression analysis, Bland-Altman plotting, and Kappa test were used for consistency analysis and the determination of consistency intensity, respectively. RESULTS: Correlation analysis showed that PCT concentrations measured from EDTA-K2 anticoagulated plasma samples had a good linear regression relationship with PCT from serum samples, with a slope of 0.8741, r = 0.958, p < 0.05. A similar correlation was observed between whole blood and serum, with a slope of 0.9234, r = 0.965, p < 0.05. A good correlation was found from the quantitative results of different sample types obtained from the same patient. In detail, PCT levels in EDTA-K2 anticoagulant whole blood and plasma are well correlated with that in the serum (r = 0.831, p < 0.05; r = 0.814, p < 0.05). There was no significant difference among different sample types (p > 0.05). Variation in PCT quantification induced by different sample types has no statistical influence on positive/negative decision (p > 0.05). Bland-Altman analysis for assessing PCT concentration agreement showed there was no outlier ratio between whole blood and plasma within the range of the detection system, as well as no outlier between serum and plasma. Kappa coefficient of PCT concentration between serum and homologous EDTA-K2 anticoagulated plasma was 0.8942 (p < 0.001), and for serum and homologous whole blood it was 0.6954 (p < 0.001). CONCLUSIONS: We concluded that quantitative PCT detection can be conducted in different sample types with good correlation and consistency, which means that it is feasible to replace serum samples with whole blood and/or plasma samples for PCT detection in clinical use. These findings reduce the sample volume and turnover time of PCT detection in clinical labs, greatly improving the process of PCT detection and promoting the application of PCT as an important inflammatory biomarker for disease diagnosis.

Magnetically Responsive Superhydrophobic Surface with Switchable Adhesivity Based on Electrostatic Air Spray Deposition.

A new method was reported for preparing a magnetically responsive superhydrophobic surface by electrostatic air spray deposition (EASD) and magnetic induction. The mixture was fully atomized under the combined action of the electrostatic field and the high-speed airflow field, and a dense array of micropillars was formed. The atomization mechanism of EASD was explored. The distribution and physical parameters of the micropillars were evaluated and counted. Switchable adhesion characteristics of the surface and the reversibility in 10 cycles were examined. The influences of different electrostatic voltages, component concentration, spray distance, air pressure, and magnetic field intensity on the surface morphology and hydrophobicity were analyzed. The prepared surface can be reversibly transformed between the high-adhesion state (with a contact angle of 108°) and the low-adhesion state (with a contact angle of 154°) by on/off switching of an external magnetic field. After a 2.2 kPa pressure load was applied, the surface contact angle was 144° with an applied magnetic field of 0.4 T. After heated at 90 °C for more than 90 min, the surface can almost obtain superhydrophobicity (with a contact angle of 148°) in the absence of a magnetic field. By utilizing the switchable surface adhesion characteristics, various kinds of droplet transmissions were realized. When the cured surface was spray-coated with carbon nanoparticles (CNPs), active droplet manipulation can be achieved by simply moving the magnet. The advantages of this method include a simple preparation process without chemical surface modification.

Bamboo-joint-like platforms for fast, long-distance, directional, and spontaneous transport of fluids.

Spontaneous transport of fluids without external force offers an enabling tool for a wide spectrum of fields. However, the development of a universal spontaneous transport platform for liquids remains a challenge. In this work, a novel bamboo-joint-like platform with tapered micro-tubes as transport units is presented, which not only enables the spontaneous transport and extrusion of liquids but also enables customized and optional assembly of transport devices. Spontaneous transport characterized with long-distance, anti-gravity transport, directional transport, and liquid extrusion characteristics was found to show excellent transport capacity. The results indicated that both transport distance and speed varied periodically with time, which was mainly due to the difference in curvature caused by asymmetric structure and capillary force. The desired spontaneous transportation was successfully obtained even when the supply rate speed was up to 632.5 µl/min and length of platform reached a scale of hundreds of millimeters. Transport units were easily fabricated via a commercially available 3D printing technique, so that the customized and directional spontaneous directional transport can be realized for liquid distribution, serpentine loop transportation, and speed control. With the comprehensive use of transport units and connectors, it is very easy to implement self-service construction of a universal complex multi-functional transportation platform.

Novel cavitation fluid jet polishing process based on negative pressure effects.

Traditional abrasive fluid jet polishing (FJP) is limited by its high-pressure equipment, unstable material removal rate, and applicability to ultra-smooth surfaces because of the evident air turbulence, fluid expansion, and a large polishing spot in high-pressure FJP. This paper presents a novel cavitation fluid jet polishing (CFJP) method and process based on FJP technology. It can implement high-efficiency polishing on small-scale surfaces in a low-pressure environment. CFJP uses the purposely designed polishing equipment with a sealed chamber, which can generate a cavitation effect in negative pressure environment. Moreover, the collapse of cavitation bubbles can spray out a high-energy microjet and shock wave to enhance the material removal. Its feasibility is verified through researching the flow behavior and the cavitation results of the negative pressure cavitation machining of pure water in reversing suction flow. The mechanism is analyzed through a computational fluid dynamics simulation. Thus, its cavitation and surface removal mechanisms in the vertical CFJP and inclined CFJP are studied. A series of polishing experiments on different materials and polishing parameters are conducted to validate its polishing performance compared with FJP. The maximum removal depth increases, and surface roughness gradually decreases with increasing negative outlet pressures. The surface becomes smooth with the increase of polishing time. The experimental results confirm that the CFJP process can realize a high material removal rate and smooth surface with low energy consumption in the low-pressure environment, together with compatible surface roughness to FJP.

ELID grinding characteristics of large stamping die for Wolter mirror.

An ultra-precision ELID grinding of large stamping dies of Wolter mirror for X-ray telescope was presented in this paper. The large stamping dies (S55C) with confocal paraboloid and hyperboloid was ground by ELID arc-enveloped grinding. In this ELID grinding system, cast iron fiber bonded (CIFB) diamond wheels were controlled by 3-dimentional ways to scan the work-piece and generate required surfaces. Its grinding characteristics such as attainable form accuracy, surface roughness were investigated. Furthermore, some measures to improve form accuracy were discussed and verified such as truing, compensating, and on-machine measuring.