Surface Properties Research Articles

Parasitoid attachment ability and the host surface wettability

Climbing animals such as geckos and arthropods developed astonishing adhesive mechanisms which are fundamental for their survival and represent valuable models for biomimetic purposes. A firm adhesion to the host surface, in order to successfully lay eggs is necessary for the reproduction of most parasitoid insects. In the present study, we performed a comparative investigation on the attachment ability of four parasitoid species (the egg parasitoid Anastatus bifasciatus (Eupelmidae), the aphid parasitoid Aphidius ervi (Braconidae), the fly pupal ectoparasitoid Muscidifurax raptorellus (Pteromalidae) and the pupal parasitoid of Drosophila Trichopria drosophilae (Diapriidae)) with hosts characterized by a surface having different wettability properties. The friction force measurements were performed on smooth artificial (glass) surfaces showing different contact angles of water. We found that attachment systems of parasitoid insects are tuned to match the wettability of the host surface. Sexual dimorphism in the attachment ability of some tested species has been also observed. The obtained results are probably related to different microstructure and chemical composition of the host surfaces and to different chemical composition of the parasitoid adhesive fluid. The data here presented can be interpreted as an adaptation, especially in the female, to the physicochemical properties of the host surface and contribute to shed light on the coevolutionary processes of parasitoid insects and their hosts.

Accurate prediction of CDR-H3 loop structures of antibodies with deep learning.

Accurate prediction of the structurally diverse complementarity determining region heavy chain 3 (CDR-H3) loop structure remains a primary and long-standing challenge for antibody modeling. Here, we present the H3-OPT toolkit for predicting the 3D structures of monoclonal antibodies and nanobodies. H3-OPT combines the strengths of AlphaFold2 with a pre-trained protein language model and provides a 2.24 Å average RMSDCα between predicted and experimentally determined CDR-H3 loops, thus outperforming other current computational methods in our non-redundant high-quality dataset. The model was validated by experimentally solving three structures of anti-VEGF nanobodies predicted by H3-OPT. We examined the potential applications of H3-OPT through analyzing antibody surface properties and antibody-antigen interactions. This structural prediction tool can be used to optimize antibody-antigen binding and engineer therapeutic antibodies with biophysical properties for specialized drug administration route.

Effect of Physicochemical Surface Properties of Silicon-Substituted Hydroxyapatite on Angiogenesis.

Synthetic hydroxyapatite (HA) is a widely studied bioceramic for bone tissue engineering (BTE) due to its similarity to the mineral component of bone. As bone mineral contains various ionic substitutions that play a crucial role in bone metabolism, the bioactivity of HA can be improved by adding small amounts of physiologically relevant ions into its crystal structure, with silicate-substituted HA (Si-HA) showing particularly promising results. Nevertheless, it remains unclear how distinct material characteristics influence the bioactivity due to the intertwined nature of surface properties. A coculture methodology was optimized and applied for in vitro quantification of the biological response. Initially, HA and Si-HA samples were produced and characterized. To compare the bioactivity of the samples, a method was developed to measure interactions in an increasingly complex environment, first including fibronectin (FN) adsorption and subsequently cell adhesion in mono and coculture using primary human osteoblasts (hOBs) and human dermal microvascular endothelial cells (HDMECs), with and without FN precoating. An experimental set-up was designed to assess to what extent different surface features of the samples contribute to the induced biological response. An 8-nm gold sputter coating was applied to eradicate the electrochemical differences and polishing and abrading was used to reduce the differences in surface topographies. Overall, 1.25 wt% Si-HA exhibited most nanoscale variations in surface potential. In terms of bioactivity, 1.25 wt% Si-HA samples induced the highest osteoblast attachment and vessel formation. Additionally, in vitro vessel formation was established on Si-HA surfaces using a hOB:HDMEC cell ratio of 70:30 and a methodology was established that enabled the assessment of the relative effect of topographical and electrochemical features induced by silicon substitution in the HA lattice on their bioactivity. It was found that the difference in the amount of protein attached to HA and 1.25 wt% Si-HA after 2 h was affected by topographical differences. Conversely, electrochemical differences induced different vessel-like structure formation in coculture with a FN precoating. Without an FN precoating, both topographical and electrochemical differences dictated the differences in angiogenic response. Overall, 1.25 wt% Si-HA surface features appear to induce the most favorable protein adsorption and cell adhesion in mono and coculture with and without FN precoating.

Coal-Based Branched Vicinal Diol Ethoxylates Versus Guerbet Alcohol Ethoxylates: Role of Tertiary Hydroxyl Groups.

Branched surfactants exhibit a lower surface tension, excellent low defoaming performance, and better wetting ability compared with linear surfactants, making them promising for applications in industrial cleaning. In this study, 2-hexyl-1-decene (C8 olefin dimer), obtained from the dimerization of 1-octene, was used as the hydrophobe to synthesize branched nonionic surfactants via hydroxylation and ethoxylation. The hydroxylation of the C8 olefin dimer to synthesize 2-hexyldecane-1,2-diol (C8 BD) using H2O2 and HCOOH was investigated systematically. Under the optimal reaction conditions (H2O2/C8 olefin dimer molar ratio: 1.5, HCOOH/C8 olefin dimer molar ratio: 4.0, reaction time: 10 h, reaction temperature: 50 °C), the conversion of the C8 olefin dimer and selectivity toward C8 BD were found to reach 99.96 and 79.89%, respectively. Further, branched nonionic surfactants (C8 BDEn) were synthesized via ethoxylation of C8 BD with ethylene oxide and characterized using FTIR, LCMS, 1H NMR, and 13C NMR techniques. The presence of a tertiary hydroxyl group in C8 BD increases the reactivity of the primary hydroxyl group, leading to a narrower range of products and lower residual substrate content. The physicochemical properties and surface properties of C8 BDEn with different degrees of ethoxylation at various concentrations were investigated and compared with those of commercially available Guerbet alcohol polyoxyethylene ethers (C8 GAEO9 and C6 GAEO9). The results show that, compared with C8 GAEO9 and C6 GAEO9, C8 BDE6 displayed a higher surface activity with a lower equilibrium surface tension (27.14 mN·m-1), superior wettability with a smaller contact angle (39.2°), better emulsification performance with a longer emulsification time of 548 s, and excellent foaming properties (initial foam volume of 11.6 mL). This strategy of utilizing coal-based α-olefins for the synthesis of branched nonionic surfactants presents a route to prepare value-added fine chemicals from coal-based resources.

ATOMISTIC CHARACTERIZATION OF HEALTHY AND DAMAGED HAIR SURFACES: A MOLECULAR DYNAMICS STUDY OF FATTY ACIDS ON PROTEIN LAYER.

We present an atomistic model for the outermost layer of the hair surface derived through molecular dynamics simulations, which comprises 18-Methyleicosanoic acid (18-MEA) fatty acid chains covalently bonded onto the keratin-associated protein 10-4 (KAP10-4) at a spacing distance of ~ 1 nm. Remarkably, this surface model facilitates the inclusion of free fatty acids (free 18-MEA) into the gaps between chemically bound 18-MEA chains, up to a maximum number that results in a packing density of 0.22 nm2 per fatty acid molecule, consistent with the optimal spacing identified through free energy analysis. Atomistic insights are provided into the organization of fatty acid chains, structural features, and interaction energies on protein-inclusive hair surface models with varying amounts of free 18-MEA (FMEA) depletion, as well as varying degrees of anionic cysteic acid from damaged bound 18-MEA (BMEA), under both dry and wet conditions. Our simulation results reveal that, while the depletion of FMEA can induce a pronounced impact on the thickness, tilt angle, and order parameters of fatty acid chains , the removal of BMEA has a marked effect on water penetration. There is a "sweet spot" spacing between the 18-MEA whereby damaged hair surface properties can be reinstated by replenishing FMEA.

On the Structure, Stability, and Cell Uptake of Nanostructured Lipid Carriers for Drug Delivery.

The efficacy of nanostructured lipid carriers (NLC) for drug delivery strongly depends on their stability and cell uptake. Both properties are governed by their compositions and internal structure. To test the effect of the lipid composition of NLC on cell uptake and stability, three kinds of liquid lipids with different degrees of unsaturation are employed. After ensuring homogeneous size distributions, the thermodynamic characteristics, stability, and mixing properties of NLC are characterized. Then the rates and predominant pathways of cell uptake are determined. Although the same surfactant is used in all cases, different uptake rates are observed. This finding contradicts the view that the surface properties of NLC are dominated by the surfactant. Instead, the uptake rates are explained by the structure of the nanocarrier. Depending on the mixing properties, some liquid lipids remain inside the nanocarrier, while other liquid lipids are present on the surface. Nanocarriers with liquid lipids on the surface are taken up more readily by the cells. This shows that the engineering of efficient lipid nanocarriers requires a delicate balance of interactions between all components of the nanocarrier on the molecular level.

Preparation of (3-Aminopropyl)triethoxysilane-Modified Silica Particles with Tunable Isoelectric Point.

Silica particles modified with amino groups hold immense potential across diverse fields, owing to their distinctive properties. The widely adopted method of surface modification, utilizing (3-aminopropyl)triethoxysilane (APTES), facilitates the incorporation of amino-functional groups onto the silica surface, thereby creating sites for subsequent functionalization with other molecules. In this context, the ability to precisely tailor the surface properties of amino-functionalized silica particles is crucial for optimizing their performance in various applications. In this work, we systematically investigated the influence of the APTES concentration and water content on the density of amino groups grafted on the silica surface within an ethanol-water mixture. The rational control of hydrolysis and condensation of APTES enabled the precise regulation of the amino density on the silica surface, resulting in a notable shift in the isoelectric point from 2.9 to 9.2. Subsequently, we assembled amino-functionalized silica with different isoelectric points with gold nanoparticles to demonstrate their tunable ability as surface-enhanced Raman scattering (SERS) substrates. This controlled and tailored amino-functionalization process opens up new routes for fine-tuning the properties of silica particles, thereby expanding their utility across various applications in materials science, nanotechnology, and biomedicine.

Functionalised Fibres as a Coupling Reinforcement Agent in Recycled Polymer Composites.

This study addresses the structure-property relationship within the green concept of wood fibres with cellulose nanofibre functionalised composites (nW-PPr) containing recycled plastic polyolefins, in particular, polypropylene (PP-r). It focuses especially on the challenges posed by nanoscience in relation to wood fibres (WF) and explores possible changes in the thermal properties, crystallinity, morphology, and mechanical properties. In a two-step methodology, wood fibres (50% wt%) were first functionalised with nanocellulose (nC; 1-9 wt%) and then, secondly, processed into composites using an extrusion process. The surface modification of nC improves its compatibility with the polymer matrix, resulting in improved adhesion, mechanical properties, and inherent biodegradability. The effects of the functionalised WF on the recycled polymer composites were investigated systematically and included analyses of the structure, crystallisation, morphology, and surface properties, as well as thermal and mechanical properties. Using a comprehensive range of techniques, including X-ray diffraction (XRD), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), zeta potential measurements, and dynamic mechanical analysis (DMA), this study aims to unravel the intricate interplay of factors affecting the performance and properties of the developed nanocellulose-functionalised wood fibre-polymer composites. The interfacial adhesion of the nW-PPr polymer composites, crystallisation process, and surface properties was improved due to the formation of an H-bond between the nW coupling agent and neat PP-r. In addition, the role of nW (1.0 wt%) as a nucleating agent resulted in increased crystallinity, or, on the other hand, promoted the interfacial interaction with the highest amount (3.0% wt%, 9.0% wt%) of nW in the PP-r preferentially between the nW and neat PP-r, and also postponed the crystallisation temperature. The changes in the isoelectric point of the nW-PPr polymer composites compared to the neat PP-r polymer indicate the acid content of the polymer composite and, consequently, the final surface morphology. Finally, the higher storage modulus of the composites compared to neat r-PP shows a dependence on improved crystallinity, morphology, and adhesion. It was clear that the results of this study contribute to a better understanding of sustainable materials and can drive the development of environmentally friendly composites applied in packaging.

Studies on the properties and molecular dynamics simulations of nonionic surfactants based on succinic acid derivatives

AbstractNonionic surfactants have proven useful in various applications such as wastewater treatment, enhanced oil recovery, dyeing, and cosmetics. Novel nonionic surfactants such as PEMP, BEMP, HEMP and BEEP were synthesized based on succinic acid derivatives and using L‐isoleucine as the linking group and four polyether alcohols as the hydrophilic group. First, the structures of the four nonionic surfactants were studied using Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectra. Then the critical micelle concentration (CMC) and surface tension at CMC (γCMC) of the four nonionic surfactants in aqueous solution were tested. γ‐lg c curves determined the relationships of their surface properties as BEEP > PEMP > BEMP > HEMP. In order to expand the range of applications for nonionic surfactants, we evaluated the salt‐resistant properties of four such surfactants. Our findings demonstrated that this class of surfactants indeed has superior salt‐resistant properties. Molecular dynamics (MD) simulations were used to study how surfactant molecules aggregate in the interfacial film. The study investigated the trend of solvent accessible surface area (SASA) over time. Results showed that the surfactant molecules interacted well with solvent molecules in the equilibrium state. This study investigates the performance differences among four types of surfactants using the electrostatic potential (ESP) distribution of their molecules. The study employed both experimental and computational simulations to provide a more comprehensive understanding of surfactant properties. The results offer insights into the theoretical research and application extension of this class of surfactants.

Towards Expanding the Use of Paper Made from Recycled and Non-Woody Plants: Enhancing the Print Quality through the Application of Nano-Modified Offset Inks

This study aims to investigate the feasibility of using paper made from eco-friendly recycled and non-woody plants in graphic technology, particularly in offset printing. Instead of changing the composition or modifying the surface properties of the paper, the focus was on enhancing the print quality by modifying the printing ink. By modifying the printing inks, the quality of the prints on recycled and non-woody paper can be optimized, which in turn reduces the need for paper made from primary fibers. This approach can expand the use of alternative materials in graphic technology and design. The objective was to optimize the print quality on these sustainable materials. Five types of uncoated paper were used, with high-quality uncoated offset paper based on virgin fibers serving as a reference. Laboratory tests of the basic and surface properties were carried out to measure the paper quality parameters that are important for offset printing. The influence of the paper composition on its optical and colorimetric properties was also investigated. The interaction between the selected papers and offset inks was examined through measurements of adhesion parameters and ink transfer, i.e., the paper’s ability to accept the ink. To enhance the applicability of the investigated papers as printing substrates in the graphic industry, SiO2 and TiO2 nanoparticles were added to the offset inks. The influence of the paper composition on the colorimetric properties of the prints was also investigated. The print uniformity, as an important quality characteristic, was determined by measuring the mottling index. The research findings indicate that incorporating SiO2 and TiO2 nanoparticles into offset inks can enhance the interaction between the paper and ink, leading to improved print quality. This study provides new perspectives on the possibilities of using recycled and non-woody plant paper in offset printing without significantly compromising the quality of the print.

STUDYING THE INFLUENCE OF PROTON IRRADIATION ON THE DISTRIBUTION PROFILE OF Pt AND Cr IN SURFACE LAYERS n-Si˂Pt˃, n-Si˂Сr˃ USING ELLIPSOMETRIC SPECTROSCOPY

In this work, the effect of high-temperature doping and proton irradiation on the depth profile and the creation of layers on the surface of single-crystal silicon was studied. The study used singlecrystal n-type silicon samples doped with phosphorus during growth. These samples were first doped with platinum and chromium and after polishing they were irradiated with protons with an energy of 2 MeV, a dose of 5.1 × 1014 cm–2 at the EG-5 accelerator. Studies of the optical properties of the sample surface were carried out using an ELLIPS-1991 spectroscopic ellipsometer at room temperature

Experimental investigation on strengthening of Zea mays root fibres for biodegradable composite materials using potassium permanganate treatment

Humans are the only species who generate waste materials that cannot be broken down by natural processes. The ideal solution to this waste problem would be to employ only compostable materials. Biodegradable materials play a key role in creating a safer and greener world. Biodegradability is the gift that keeps on giving, in the sense of creating an Earth worth living. The future is thus best served by green energy, sustainability, and renewable resources. To realize such goals, waste should be considered as a valuable resource. In this context, Zea mays (Zm) root fibres, which are normally considered as agricultural waste, can be used as reinforcing substances in polymer matrices to produce structural composite materials. Before being used in composites, such fibres must be analysed for their physical properties. Chemical treatments can be employed to improve the structural quality of fibres, and the changes due to such modification can be analysed. Therefore, the current work examines the effect of permanganate treatment on the surface properties of Zm fibres. The raw and potassium permanganate-treated samples were assayed for various properties. Physical analysis of the fibre samples yielded details concerning the physical aspects of the fibres. The thermal conductivity and moisture absorption behaviour of the samples were analysed. Chemical analysis was employed to characterize the composition of both treated and untreated samples. p-XRD was employed to examine the crystalline nature of the Zm fibres. Numerous functional groups present in each sample were analysed by FTIR. Thermogravimetric analysis was used to determine the thermal stability of Zm fibres. Elemental analysis (CHNS and EDS) was used to determine the elemental concentrations of both raw and treated samples. The surface alterations of Zm fibres brought on by treatment were described using SEM analysis. The characteristics of Zm roots and the changes in quality due to treatment were reviewed, and there were noticeable effects due to the treatment. Both samples would have applications in various fields, and each could be used as a potential reinforcing material in the production of efficient bio-composites.

How liquids charge the superhydrophobic surfaces

Liquid-solid contact electrification (CE) is essential to diverse applications. Exploiting its full implementation requires an in-depth understanding and fine-grained control of charge carriers (electrons and/or ions) during CE. Here, we decouple the electrons and ions during liquid-solid CE by designing binary superhydrophobic surfaces that eliminate liquid and ion residues on the surfaces and simultaneously enable us to regulate surface properties, namely work function, to control electron transfers. We find the existence of a linear relationship between the work function of superhydrophobic surfaces and the as-generated charges in liquids, implying that liquid-solid CE arises from electron transfer due to the work function difference between two contacting surfaces. We also rule out the possibility of ion transfer during CE occurring on superhydrophobic surfaces by proving the absence of ions on superhydrophobic surfaces after contact with ion-enriched acidic, alkaline, and salt liquids. Our findings stand in contrast to existing liquid-solid CE studies, and the new insights learned offer the potential to explore more applications.

Vat photopolymerization based Photoinhibition aided Ceramic additive manufacturing (PinCAM)

Vat photopolymerization (VPP) in ceramic additive manufacturing (CAM) faces challenges due to high viscosity from ceramic powder loading, necessitating interruptive recoating steps. Ceramic particles also attenuate and divert irradiated light, causing reduced cure depth and over-curing, leading to slow print, weak interlay adhesion, and dimensional errors. This study introduces photo inhibition-aided CAM (PinCAM) using dual-wavelength digital light processing to mitigate these issues. PinCAM employs two optical masks for initiation and inhibition at different wavelengths. While previous research focused on polymers, this work evaluates inhibition's effects in suspension-based VPP-CAM. Modeling and experiments examine inhibition and curing characteristics, print speed, dimensional accuracy, surface roughness, and microstructure. Preliminary results suggest that photoinhibition has the potential to enhance geometrical and surface properties as well as particle distribution homogeneity of green ceramic components without significantly compromising print speed. Understanding inhibition's impact will aid further research in PinCAM optimization for rapid and precise ceramic manufacturing.

Synthesis of Polymer Brushes on Tannic Acid-Coated Copper Particles and Surface Co-Assembly.

The synthesis of polymer brushes on inorganic particles is an effective approach to surface modification. The polymer brushes on the surface endow the substrates with new surface properties. However, the lack of functional groups and the difficulty of surface modification have made it difficult to develop an effective method for the synthesis of polymer brushes on metal surfaces. Herein, a simple and versatile strategy for synthesizing polymer brushes on copper particles is reported. Tannic acid (TA) molecules are adsorbed onto the surfaces of copper particles, forming TA coatings. Quaternized poly(2-(dimethylamino)ethyl methacrylate)-block-polystyrene (qPDMAEMA-b-PS) block copolymer (BCP) chains are grafted on the TA coatings through hydrogen bonding and electrostatic interaction, and PS brushes are grafted on the copper particles. The effects of TA concentration on the adsorption of TA and PS brush synthesis are discussed. The PS brushes are able to form surface nanostructures on the copper particles through co-assembly with PDMAEMA-b-PS BCP chains. The effect of BCP concentration on the surface nanostructures is investigated. It is reasonable to expect that polymer brushes and surface nanostructures can be synthesized on different metal surfaces by using the TA-coating approach reported in this paper.

Effect of interlayer bonded bilayer graphene on friction

Abstract We study the friction properties of interlayer bonded bilayer graphene by simulating the movement of slider on the surface of bilayer graphene using molecular dynamics. The results show that the presence of the interlayer covalent bonds due to the local sp3 hybridization of carbon atoms in the bilayer graphene seriously reduced the frictional coefficient of the bilayer graphene surface to 30%, depending on the coverage of interlayer sp3 bonds and normal loads. For a certain coverage of interlayer sp3 bonds, when the normal load of the slider reaches a certain value, the surface of this interlayer bonded bilayer graphene will lose the friction reduction effect on the slider. Our findings provide guidance for the regulation and manipulation of the frictional properties of bilayer graphene surfaces through interlayer covalent bonds, which may be useful for the application of friction related graphene based nanodevices.

Biofunctionalisation strategies of material surface and the inspired biological effects for bone repair

AbstractDue to trauma and disease, bone defects endanger the healthy life of human beings. At present, the gold standard for bone defect repair is still autologous bone transplantation and allogeneic bone transplantation. However, its insufficient source, potential disease transmission and immune rejection limit its clinical application. Therefore, the development of bone repair materials plays an important role in promoting bone repair. As the interface between material and tissue, the surface of the material plays an important role in the reaction after implantation, which determines the effectiveness of defect repair treatment. With the development of surface engineering and technology, bone repair materials have developed from biological inertia to biological activity by endowing various biological functions by controlling the composition, topological morphology and structure of the material surface etc. The inspired biofunctionalisation of material surface includes the capacities of inducing osteogenesis, promoting angiogenesis, antibacterial, immune regulation etc., as well as integration of postoperative repair and treatment. The authors review the biofunctionalisation of biomaterial surface and the inspired biological effects for bone repair, mainly including physical and chemical properties of material surface to regulate osteogenesis, and functional strategy of bone repair material surface.

Application and Development of Electrospun Nanofiber Scaffolds for Bone Tissue Engineering.

Nanofiber scaffolds have gained significant attention in the field of bone tissue engineering. Electrospinning, a straightforward and efficient technique for producing nanofibers, has been extensively researched. When used in bone tissue engineering scaffolds, electrospun nanofibers with suitable surface properties promote new bone tissue growth and enhance cell adhesion. Recent advancements in electrospinning technology have provided innovative approaches for scaffold fabrication in bone tissue engineering. This review comprehensively examines the utilization of electrospun nanofibers in bone tissue engineering scaffolds and evaluates the relevant literature. The review begins by presenting the fundamental principles and methodologies of electrospinning. It then discusses various materials used in the production of electrospun nanofiber scaffolds for bone tissue engineering, including natural and synthetic polymers, as well as certain inorganic materials. The challenges associated with these materials are also described. The review focuses on novel electrospinning techniques for scaffold construction in bone tissue engineering, such as multilayer nanofibers, multifluid electrospinning, and the integration of electrospinning with other methods. Recent advancements in electrospinning technology have enabled the fabrication of precisely aligned nanofiber scaffolds with nanoscale architectures. These innovative methods also facilitate the fabrication of biomimetic structures, wherein bioactive substances can be incorporated and released in a controlled manner for drug delivery purposes. Moreover, they address issues encountered with traditional electrospun nanofibers, such as mechanical characteristics and biocompatibility. Consequently, the development and implementation of novel electrospinning technologies have revolutionized scaffold fabrication for bone tissue engineering.

Hybrid photo paper-based microfluidic device for colorimetric detection of iodine in salt

Microfluidic paper-based analytical devices (µPADs) have gained widespread use in various analytical applications because they are low-cost and suitable for onsite testing. The development of µPADs, including fabrication methods, new materials, and enhancement functionality is crucial to advance their practical application in analytical chemistry. In this study, we introduce a new hybrid paper-based analytical device, the hybrid photo paper-based microfluidic device (hPPMD), which combines a photo paper-based microfluidic device (PPMD) with a µPAD. We conducted a systematic study that detailed hPPMD’s characteristics, including surface properties and fluidic transportation. The hPPMD showed two fluidic transportation behaviors: continuous flow and discontinuous flow at the device junction, depending on the orientation of the device combination. Our hPPMD could increase fluidic flow approximately four times the speed when six layers of guided channels were added. The customized hPPMD was used for colorimetric detection of iodine in table salt, and then the result was quantitatively analyzed using a computer and smartphone with color analysis software. The detection zones of the hPPMD showed a flawless circular color signal. Under optimum conditions, the hPPMD was sensitive enough to detect iodine in salt solutions at various concentrations ranging from 1 to 100 ppm. The developed hPPMD should be a simple and low-cost analytical device for onsite qualitative analysis of the iodine and other chemical contaminants in food and the environment.

A novel activation method for regulating surface characteristics and flotation performance of smithsonite: XPS, SEM-EDS, AFM, ToF-SIMS and FT-IR studies

Smithsonite is a typical zinc oxide mineral, and the flotation index is not ideal for the recovery of smithsonite via sulfidization–xanthate flotation. In this study, Pb2+ was used as an activator for the stepwise activation of smithsonite in a sulfidization–xanthate flotation system. Micro-flotation tests and various surface analytical assays were employed to investigate the effects of Pb2+ stepwise activation on the flotation behavior and surface properties of smithsonite. The micro-flotation tests revealed that the flotation recovery of smithsonite reached 90.26 % after the stepwise activation of Pb2+ at an appropriate concentration. X-ray photoelectron spectroscopy, scanning electron microscopy-energy-dispersive X-ray spectroscopy, atomic force microscopy, and time-of-flight secondary ion mass spectrometry indicated that abundant active sites of Pb components appeared on the smithsonite surface after Pb2+ stepwise activation, which promoted the adsorption of S ions on the smithsonite surface. The increase in the proportion of the PbS component after sulfidization effectively enhanced the reaction activity of the mineral surface. Fourier-transform infrared spectroscopy and contact angle measurements showed that xanthate could be stably adsorbed on the smithsonite surface after Pb2+ stepwise activation, thereby enhancing the surface hydrophobicity and flotation behavior of smithsonite. Therefore, Pb2+ stepwise activation can promote sulfidization on the smithsonite surface, improve the reactivity and hydrophobicity of the mineral surface, and substantially increase the flotation index of smithsonite.