Control Of Surface Properties Research Articles

Enhanced performance of electrospun PVDF membranes modified with rare-earth metal oxides for membrane distillation: A systematic study

In the presented studies, the novel type of separation materials dedicated to membrane distillation was generated and systematically analyzed. Utilizing poly(vinylidene fluoride) (PVDF) electrospun membranes as a base, hybrid organic-inorganic materials were developed to enhance performance. These materials exhibited high hydrophobicity, featuring superhydrophobicity on a micro-scale due to fractal-like structures on the inorganic domain surface. Rare-earth metal oxides (REMO) were implemented for the first time as smart modifiers, covalently attached to the functionalized membrane surface. Three REMO types were selected to investigate their impact on membrane performance in air-gap membrane distillation (AGMD) for the desalination process. Chemical attachment via long enough linkers formed a flexible active surface structure, facilitating transport and separation. Dynamic goniometric studies evaluated membrane wetting stability. Particularly noteworthy was the membrane enhanced with Ho2O3 particles, with high flux and salt rejection rates of 14.41 ± 1.35 kg m−2 h−1 and >99.5 %, respectively. The membrane stability and affinity were further examined using Hansen Solubility Parameters and Pearson's hard–soft acid–base (HSAB) theory. The potential of the hybrid membranes is seen not only in desalination. With the ability to control surface properties by using different silane linkers, oleophobicity/oleophilicity can be achieved, and practical use in wastewater treatment or oil/water separation is possible.

Microstructure evolution of ATI718 plus alloy during high-speed machining: Experiments and a combined FE-CA approach

Excellent surface integrity is an eternal pursuit in high performance manufacturing, with microstructure being a crucial component of the surface integrity dataset and a key factor controlling surface properties such as fatigue and creep. The multi-physical fields generated by thermo-mechanical loads during high-speed machining act on the processed surface layer, influencing the evolution of microstructures. To investigate the microstructural evolution mechanisms of ATI718 plus during high-speed machining, cutting experiments and techniques such as Electron back scatter diffraction (EBSD), Transmission Kikuchi diffraction (TKD), and Precession electron diffraction (PED) is conducted to quantitatively analyze the microstructures in the chip shear zone and the machined surface. Subsequently, a combined finite element (FE) and cellular automata (CA) model is developed to simulate the microstructure evolution during the cutting process. The discontinuous dynamic recrystallization (DDRX) mechanism is employed to demonstrate the nucleation and growth of grains under the influence of multiple physical fields. The simulation and experimental results show similar dynamic recrystallization (DRX) grain sizes, indicating acceptable accuracy of the CA model in terms of DRX grain size. The comparison between experimental and simulation results confirms the occurrence of both continuous dynamic recrystallization (CDRX) and DDRX during the cutting process. The synergistic competition between CDRX induced grain lamellar refinement and DDRX induced grain growth emerge as the primary mechanism driving microstructural evolution. A layer of ultrafine grains, with a thickness within 20 μm, is formed on the machined surface. Results under different parameters demonstrate that the temperature has a more significant impact on the thickness of the ultrafine grain layer and the diameter of grains within the layer compared to the strain rate.

Fluorinated paracyclophane dimers for polymeric thin films via chemical vapor polymerization

Poly(para-xylylene) thin films from Gorham method via chemical vapor polymerization (CVP) process (so called Parylene) have been extensively utilized in various application fields. Specific functional groups can be also introduced into thin polymeric films via CVP process using functionalized paracyclophane dimer. There have been numerous efforts to fabricate parylene thin films using synthesized and functionalized paracyclophane dimers so far. Herein we report on synthesis of fluorine containing paracyclophane dimers and their polymeric thin films via Gorham method. Three different types of fluorine containing paracyclophane derivatives are synthesized and the CVP thin films are prepared in all cases by adjusting processing condition. Even though the functional groups on parylene thin films are similar, dramatic differences in surface energy can be observed. This work can provide extended material choices for whom want to precisely control surface properties with robust, pin-hole free, and conformal coatable polymeric thin films.

CTAC-assisted monoclinic BiVO4 with oxygen defects for efficient photocatalytic performances: A combined experimental and DFT study

Developing a photocatalyst with high photocatalytic efficiency, chemical stability, and self-degradation capability is essential for optimizing photodegradation processes in environmental applications. In this study, we synthesized a monoclinic BiVO4 photocatalyst whose surface morphology was modulated by hexadecyltrimethylammonium chloride (CTAC) using a facile hydrothermal method. Experimental results demonstrated a substantial increase in the degradation rate (99%) for the CTAC-modified monoclinic BV/CT25 photocatalyst (with an initial CTAC concentration of 25 g/L) compared to the CTAC-free tetragonal BiVO4 photocatalyst (73%). This highlights the effective enhancement of photocatalytic degradation performance through CTAC modification. Furthermore, density functional theory (DFT) calculations revealed that the band gap of BV/CT25 remained unchanged, suggesting that changes in oxygen vacancies (OVs) and density of states, along with the porous lattice structure, contributed to the improved performance. These findings were further supported by FESEM, as well as EPR and XPS characterizations. In addition, photodegradation tests at various pH conditions and cyclic tests suggested that the modification enhanced the morphological stability and reusability of the modified BiVO4 photocatalysts. Overall, this study provides valuable insights into the design of next-generation photocatalysts, leveraging surfactants to control surface properties and emphasizing the key attributes of high photocatalytic efficiency, chemical stability, and improved reusability.

Bioinspired carbon nanotube-based nanofluidic ionic transistor with ultrahigh switching capabilities for logic circuits.

The voltage-gated ion channels, also known as ionic transistors, play substantial roles in biological systems and ion-ion selective separation. However, implementing the ultrafast switchable capabilities and polarity switching of ionic transistors remains a challenge. Here, we report a nanofluidic ionic transistor based on carbon nanotubes, which exhibits an on/off ratio of 104 at operational gate voltage as low as 1 V. By controlling the morphology of carbon nanotubes, both unipolar and ambipolar ionic transistors are realized, and their on/off ratio can be further improved by introducing an Al2O3 dielectric layer. Meanwhile, this ionic transistor enables the polarity switching between p-type and n-type by controlled surface properties of carbon nanotubes. The implementation of constructing ionic circuits based on ionic transistors is demonstrated, which enables the creation of NOT, NAND, and NOR logic gates. The ionic transistors are expected to have profound implications for low-energy consumption computing devices and brain-machine interfacing.

Structure and Interaction in 2D Organized Assembles of Cationic Lipids with Tryptophan: An Experimental and Computational Investigation

Molecular association of lipid membranes is an important tool to understand their biological functions. Engineered nano/microscopic lipid surface structures enable controlled surface properties such as adhesion, wetting and molecular recognition,...

(Invited) Negative Ions, Nanoparticles and Their Transport to Substrates: Towards Better Control of Plasma-Based Fabrication of Surfaces with Tunable Wetting Properties

The removal of pollutants from water, such as oil residues, requires the production of materials with controlled surface properties, especially in terms of their specific surface area and wetting properties [1]. Environmentally friendly processes based on plasma techniques enable the production of surfaces with a wide variety of different properties in terms of their surface topography and chemical composition. An important component that often forms in low-temperature plasmas operated with organic monomers are nanoparticles. Although often considered an undesirable side effect in many applications, nanoparticles can also be used to create nanocomposites or to decorate surfaces to control their wetting properties and their surface roughness [2]. In order to harness the nanoparticles from a plasma it is therefore an essential task to control their formation and ultimately their transport to the reactor walls or to potential substrates. This contribution will focus on the formation of nanoparticles in low temperature, low pressure plasmas operated with different organic monomers as a precursor gas. Although the exact mechanism responsible for the creation of nanoparticles clearly depends on the nature of the process, it is believed that negative ions play a crucial role in the initial stages of the nucleation [3]. In contrast to neutral radicals or positive ions, which are rapidly lost due to diffusion to the reactor walls the residence time of negative ions in the plasma bulk is usually much larger. Negative ions can therefore more easily form larger molecules, which can serve as the basis for the formation of primary clusters in the nanometer or subnanometer range and in this way trigger the agglomeration processes that lead to the formation of larger particles. Since negative ions can leave the plasma during the plasma-off phase of a pulsed discharge, pulsing the plasma is a suitable means to control the accumulation of negative ions and thus the formation of nanoclusters. The experimental results show a complex interplay between pulse frequency or duty cycle and nanoparticle formation. Even the smallest changes in plasma off-time can lead either to a discharge regime that favors nanoparticle formation or to a discharge regime that prevents nanoparticle formation. The minimum plasma off time required to prevent the build- up of particles in a pulsed discharge depends strongly on parameters like power, pressure, gas mixture ratio and the plasma on time. Although the formation of nanoparticles can be very precisely controlled by an appropriate choice of pulse frequency and duty cycle, their transport and controlled deposition on substrates remains a difficult task. In this context, the use of new structured "filtering" electrodes [4] is discussed. The results show that these electrodes allow the deposition of materials with very different surface topographies. Depending on the plasma conditions and the DC voltages applied to parts of the electrodes, the resulting deposits can range from highly localized polymer structures to dense layers of nanoparticles or polymer films with Turing-like patterns. Literature [1] M. Padaki, R. Surya Murali , M.S. Abdullah, N. Misdan , A. Moslehyani , M.A. Kassim , N. Hilal , A.F. Ismail , Desalination, 357,P. 197 (2015)[2] Berndt, J., Acid, H., Kovacevic, E., Boufendi, L., Journal of Applied Physics, 113(6), p.063302. (2013)[3] Berndt, J., Kovacevic, E., Boufendi,L. Journal of Applied Physics, 106, 063309 (2009)[4] Sciacqua, D., Pattyn, C., Jagodar, A., von Wahl, E., Lecas, T., Strunskus, T., Kovacevic, E. and Berndt, J., 2020.. Scientific Reports, 10(1), pp.1-8. Acknowledgement Authors acknowledge the project PEGASUS (Plasma Enabled and Graphene Allowed Synthesis of Unique nano- Structures), funded by the European Union's Horizon research and innovation programme under grant agreement No 766894 and the EU Graphene Flagship FLAG-ERA III JTC 2021 project VEGA (PR-11938). TS, CB ,and JB want to thank HZB for the allocation of synchrotron radiation beamtime at Bessy II. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 730872 (Nr. 18207084-ST and 18207393- ST). TV, CB and JB acknowledge also support obtained via ARD MATEX Region Centre and Erasmus + Program with WHS Recklinghausen and Prof dr Franziska Traeger.

A strategy to develop hydrophobic stainless steel mesh through three-component coupling reaction with presence of sulfur

Metal meshes with controlled surface properties have shown great potential for oil–water separation. However, it is still challenging to prepare cost-effective meshes to satisfy the material requirements under a variety of harsh conditions. In this study, polydopamine was deposited on the surface of stainless steel mesh to provide amine groups as active sites, and a series of modification strategies were constructed through sulfur-based three-component coupling reactions between the amine-functionalized mesh and aliphatic amine, alkyne, isocyanide. The prepared metal meshes showed excellent hydrophobicity with water contact angle in the range of 131–142° and could be used to separate a series of oil–water mixtures with separation efficiency above 99 % and flux higher than 2.3 × 104 L/m2/h. In addition, the separation capabilities of the developed meshes remained stable after 10 cyclic operations. More significantly, the modified meshes could tolerate repeated and prolonged usage and demonstrated excellent stability under various chemical conditions. It was found that the sulfur-based three-component reaction was a versatile way to get functional surface for metal substrate.

Hybrid ceramic nanofiltration membranes prepared by impregnation and solid-state grafting of organo-phosphonic acids

Grafting of oligomers into the mesopores of ceramic membranes (e.g. γ-alumina) represents an attractive strategy for deploying durable, resistant, and efficient hybrid membranes for the industrial treatment of wastewater containing organic solvents and divers solutes. In general, to control the membrane/solute/solvent interactions, homogeneous surface modification and high grafting yields are required. However, reaching this goal is rather challenging with the current grafting approaches where the active diffusion of the oligomers to the membrane pore surface may be hampered. To mitigate such diffusion limitation, we present here a novel synthesis method consisting of an infiltration of concentrated PEG organophosphonic acid oligomer solution in ceramic ultrafiltration membranes before initiating the solid-state grafting reaction to form a PEG-brush-grafted nanofiltration ceramic membrane. The infiltration step was found to be decisive for the formation of weak bonds between the oligomer linking functions and the ceramic membrane ensuring the final synthesis of robust PEG-based membranes by a grafting reaction. The influence of the solvent polarity (water vs. cyclohexane) on the conformation of the grafted PEG brush inside the γ-alumina mesopores was observed as a key parameter in the analysis of the pore size and permeability results. In addition to this, it was studied here for the first time by molecular dynamic simulations. The as-prepared PEG-brush/ceramic membranes were found very efficient in the separation of small organic dyes such as Rhodamine B (479 g mol−1) up to 85%. As a result, the present synthesis method represents a sustainable and simple alternative way for the preparation of hybrid nanofiltration membranes with controlled surface properties and attractive separation performance. Moreover, the vacuum impregnation and solid-state grafting approach requires a minimal amount of functional oligomers and solvent (0.5 mmol for 2–3 mL of solvent) and can be applied to other porous materials used in separation technologies.

Surfactant-Assisted Synthesis of Mesoporous Metal Phosphonates to Control Surface Properties Including an Opportunity to Organize a Bulky Biphenyl Linker.

A wide variety of properties by the presence of functional organic groups have so far been investigated by using periodic mesoporous organosilica (PMO)-type materials but not yet discussed with surface properties that are controlled through the success in synthesizing analogous non-silica-based hybrid mesoporous materials and subsequent evaluation and/or comparison of their properties. Here, we demonstrated the advance in synthesizing biphenyl group (-Ph-Ph-, also expressed as -2Ph)-containing mesoporous metal phosphonates with a rational understanding of surface properties. Ordered mesoporous films of aluminum and titanium ones (AOP-2Ph and TiOP-2Ph) were fabricated by spin-coating and their powders were recovered by spray-drying with the confined assembly of spherical mesopores. As in the case of PMO-type materials, the possibility to organize a -Ph-Ph- linker at the molecular scale was found in the powder samples of AOP-2Ph and TiOP-2Ph because thick frameworks would give an opportunity to organize the bulky -Ph-Ph- linker as the small-sized domains even around spherical mesopores. Surface properties of AOP-2Ph and TiOP-2Ph were evaluated by using the data of water (H2O) adsorption isotherms and compared with those containing different organic groups. The unique hydrophilicity starting from the hydration of AlO4 units was drastically reduced by the presence of -Ph-Ph- groups with a disappearance of the capillary condensation by the presence of mesopores. In addition, a partial replacement of TiO6 units with AlO4 and/or its hydrated AlO6 species was proposed for decreasing the strong hydrophobicity of TiOP-2Ph. The contact angle over the spin-coated films was also measured by using a droplet of H2O, indicating that the surface of the films, especially TiOP-2Ph, was extremely hydrophilic. Although surface properties at the molecular scale can be evaluated by using molecular H2O vapor during the measurement of H2O adsorption isotherms, the interaction of the H2O cluster (droplet) with the bulk surface seems to be predominated by inorganic moieties.

Cell patterning on photocrosslinkable polymer films with micropatternable surfaces

AbstractThe regulation of cell behavior is crucial for understanding many fundamental biological processes and designing novel medical devices. Nano/micropatterning has been developed as a means of controlling cellular properties and behaviors. Using cinnamoyl groups that have undergone photodimerization, we have prepared facile photopatterning films with adjustable surface properties for cell patterning via simple steps. Our strategy for controlling surface properties uses the decrease in free volume induced by photocrosslinking. This paper describes the surface‐patterning properties of photocrosslinkable polymer films and the cell adhesion to their micropatterned surfaces. Upon culturing cells on micropatterned surfaces, preferential cell adhesion, alignment and proliferation are observed in the unexposed regions. Additionally, diverse surface patterns of photocrosslinkable polymer films have been fabricated using various photomasks, enabling effective control of cell adhesion and alignment. The ability to regulate cellular behavior via microfabricated surfaces of photocrosslinkable polymer films enables a new and facile approach for designing scaffolds for the development of novel advanced materials, tissue engineering, and regenerative medicine.

A Facile and Green Microwave‐Assisted Strategy to Induce Surface Properties on Complex‐Shape Polymeric 3D Printed Structures

AbstractLight‐ induced polymeric 3D printing is becoming a well‐established fabrication method, showing manifold advantages such as control of the local chemistry of the manufactured devices. It can be considered a green technology, since the parts are produced when needed and with minimum amount of materials. In this work 3D printing is combined with another green technology, microwave‐assisted reaction, to fabricate objects of complex geometry with controllable surface properties, exploiting the presence of remaining functional groups on the surface of 3D printed specimens. In this context, surface functionalization with different amines is studied, optimizing formulations, reaction times, and avoiding surface deterioration. Then, two different applications are investigated. MW‐functionalized filter‐type structures have been tested against Staphylococcus aureus bacteria, showing high bactericidal activity on the surface along all areas of the complex‐shaped structure. Second, a fluidic chip composed of three separated channels is 3D printed, filled with different amine‐reactive dyes (dansyl and eosine derivatives), and made to react simultaneously. Complete and independent functionalization of the surface of the three channels is achieved only after 2 min of irradiation. This study demonstrates that light induced 3D printing and microwave‐induced chemistry can be used together effectively, and used to produce functional devices.

Controlling Surface of Rods With Entrained Particle as Asperities

Abstract Changing the surface properties (i.e., roughness or friction) can be instrumental for many applications but can be a complex and resource-intensive process. In this paper, we demonstrate a novel process of controlling the friction of a continuous rod by delivering inorganic microparticles. A standardized continuous particle transfer protocol has been developed in our laboratory for depositing particles from a liquid carrier system (LCS) to the cylindrical rod substrate. The particle transfer process can produce controllable and tunable surface properties. Polymeric binder is used to deliver the particles as asperities over the rod substrate and by controlling their size, shape, and distribution, the coefficient of friction of the rod is determined. Tabletop experiments are designed and performed to measure the friction coefficient following the Capstan equation. The entrained particles on the substrate will create size- and shape-based asperities, which will alter the surface morphology toward the desired direction. Both oblique and direct quantitative measurements are performed at different particles and binder concentrations. A systematic variation in the friction coefficient is observed and reported in the result section. It is observed from the capstan experiment that adding only 1% irregular shaped particles in the suspension changes the friction coefficient of the rods by almost 115%. The proposed friction control technique is a simple scale-up, low-cost, low-waste, and low-energy manufacturing method for controlling the surface morphology.

Porous Cu-based metal organic framework (Cu-MOF) for highly selective adsorption of organic pollutants

In this study, copper based metal organic frame work (Cu-MOF) was synthesized by using different solvents i. e. H2O, Dimethylformamide (DMF) and DMF ​+ ​C2H5OH ​+ ​H2O solutions at various temperatures. Cu-MOF synthesized in different solvents exhibited a large number of properties and advantages including easy synthesis procedure, high porosity, good crystallinity, high surface area, massive pore volume, controllable pore surface properties (zeta potential), rigid and chemical stability. The as-synthesized Cu- MOF was analysed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area, zeta potential, electrostatic attraction and Thermal gravimetric analysis (TGA). A higher BET surface area of 121.1 ​m2 ​g−1 was obtained for Cu-MOF synthesized in DMF ​+ ​C2H5OH ​+ ​H2O compared with H2O (109.3 ​m2 ​g−1) and DMF (115.1 ​m2 ​g−1) solvents. The as-obtained Cu-MOF was used to investigate adsorption kinetic performances of methylene blue (MB) and methyl orange (MO) dye molecules. Compared with other samples, Cu-MOF synthesized in (DMF ​+ ​C2H5OH ​+ ​H2O) has a significantly enhanced adsorption ability for MB but a lower for MO dyes. After 4 ​min, the adsorption co-efficient (k) values were calculated to be 0.506, 0.846 and 1.1915 min−1 for MB and 0.029, 0.024 and 0.005 min−1 for MO dyes for Cu-MOF (H2O), Cu-MOF (DMF) and Cu-MOF (DMF ​+ ​C2H5OH ​+ ​H2O), respectively. It was found that Cu-MOF has a higher adsorption for MB dye but a poor adsorption capacity for MO, which was attributed to the electrostatic attraction/repulsion phenomena. Moreover, compared with Cu-MOF (DMF) and Cu-MOF (H2O), Cu-MOF (DMF ​+ ​C2H5OH ​+ ​H2O) shows an improved stability at 370, 417 and 423 ​°C temperatures. The result obtained through experiment suggested that porous Cu-MOF microstructures synthesized in DMF ​+ ​C2H5OH ​+ ​H2O have potential application for the treatment wastewaters having MB and MO dyes.

Development and evaluation of a sensory panel for collecting reliable player perceptions of third-generation synthetic turf football surfaces

Perceptions of synthetic surfaces used in football can vary considerably between players, and obtaining reliable feedback is challenging. The aim of this study was to develop a suitable process and evaluate the merits of establishing a sensory panel to assess the subjective attributes of third generation synthetic turf surfaces (3G turf) used in football. Focus groups with 12 male and 13 female footballers were conducted on an outdoor 3G turf pitch to develop a common language to describe sensory feedback related to player–surface interactions. Post-session analysis revealed two main themes related to player–surface interactions: hardness and grip. These themes were broken down further into five sensory attributes (Movement Speed, Slip, Movement Confidence, Leg Shock and Give) which were investigated further in an indoor test area containing ten 3G turf surfaces with controlled surface properties. A panel consisting of 18 University footballers (11 male and 7 female) undertook a screening and training session to refine the language associated with the sensory attributes and become familiar with the testing protocol. During a final evaluation session, players were asked to discriminate between surfaces using the paired comparison method for each of the sensory attributes. Player consistency remained similar between the screening and evaluation sessions whilst the panel’s ability to discriminate between surfaces improved during the evaluation session. Sensory training can therefore be a useful approach to aid players in differentiating between surfaces and lead to a greater understanding of athlete perceptions of surface attributes.

Magnetic triazine-based dendrimer as a versatile nanocarrier for efficient antiviral drugs delivery

Nanoscale engineering is an efficient method for the treatment of multiple infectious diseases. Due to the controllable functionalities, surface properties, and internal cavities, dendrimer-based nanoparticles represent high performance in drug delivery, making their application attractive in pharmaceutical and medicinal chemistry. In this study, a dendritic nanostructure (Fe3O4@SiO2@TAD-G3) was designed and fabricated by grafting a triazine-based dendrimer on a magnetic nanomaterial. The structure of synthesized hybrid nanostructure was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), energy-dispersive X-ray (EDX) spectroscopy, elemental mapping, scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and vibrating sample magnetometry (VSM). The prepared nanostructure (Fe3O4@SiO2@TAD-G3) combines the unique properties of magnetic nanoparticles and a hyperbranched dendrimer for biomedical applications. Its dual nature and highly exposed active sites, could make the transportation of drugs to targeted sites of interest through the magnetic field. A study was conducted on model drugs loading (Favipiravir and Zidovudine) and in vitro release behaviour of Fe3O4@SiO2@TAD-G3, which was monitored by ultraviolet spectroscopy. The dendritic nanostructure exhibited high drug-loading capacity for Favipiravir (63.2%) and Zidovudine (76.5%). About (90.8% and 80.2%) and (95.5% and 83.4%) of loaded Favipiravir and Zidovudine were released from Fe3O4@SiO2@TAD-G3 at pH 1.5 and 6.8 respectively, within 600 min and at 37 °C. The initial fast release attributed to the drug molecules on the surface of nanostructure while the drugs incorporated deeply into the pores of the Fe3O4@SiO2@TAD-G3 released with a delay. We proposed that Fe3O4@SiO2@TAD-G3 could be tested as an effective carrier in the targeted (cellular or tissue) delivery of drugs. We think that the prepared nanostructure will not deposit in the liver and lungs due to the small size of the nanoparticles.

Computational Analysis to Optimize the Performance of Thin Film Liquid Crystal Biosensors

A nonlinear unsteady-state mathematical model employing torque balance and Frank free energy according to the Leslie-Ericksen continuum theory is developed and implemented to simulate the performance of nematic liquid crystal biosensor films with aqueous interfaces. A transient liquid crystal-aqueous interface realignment is modeled using the Euler–Lagrange equation by changing the easy axis when the surfactant molecules at the interface are introduced. In our study, we evaluated the dynamics between bulk and interface by controlling surface properties of the interface, such as homeotropic anchoring energy and surface viscosity. In addition, transient optical interference and response time have been examined in this study. Our parametric study results indicated that both homeotropic anchoring energy and surface viscosity at the interface contribute to bulk reorientation. Furthermore, the obtained numerical results indicate that as homeotropic anchoring strength increases, the effective birefringence decreases more gradual due to the increasing surfactant concentration at the aqueous interface, consistent with available experimental observations. Our results have been validated and compared to experimental results from thin-film liquid crystal biosensors in this study.

ZrO2-based catalysts for biodiesel production: A review

ZrO2-based catalysts are remarkable catalyst with unique advantageous in transesterification and esterification for biodiesel production. Various modifications have been conducted refer to a specified surface properties consist of surface acidity/basicity, specific surface area and porosity, hydrophobicity, and catalysts stability. Summary on the basic concept on catalyst synthesis, applicability for various feedstocks along with their reusability aspect in biodiesel production are discussed in this review. Even though the activity of the catalyst is depending on many factors including the oil feedstocks, reaction temperature, molar ratio of oil to methanol, and other conditions, the controllable surface properties of catalyst is a benefit of ZrO2-based catalysts. The recyclability and reusability of the catalyst become important aspect for developing a sustainable biodiesel production in the perspective of green chemistry. In addition, future perspective to make sure the applicability of the catalyst for a sustainable process by life cycle assessment is highlighted in this review.

Controlling Surface-Immobilized Elastin-like Peptides for Electrochemical Sensing Applications

Surface-immobilized elastin-like peptides (ELPs), known for their stimuli-responsive behavior, represent a promising biomolecular platform for electrochemical sensing. Key to the success of this applications is understanding how ELPs assemble on electrode surfaces, how the assembly and configuration can be controlled, and how their structure impacts the accessibility of the solid surface to redox active species. Here, we share recent work where short ELPs with varying guest residues and sequence length were designed for gold electrode attachment, and the ability of a redox probe to access a gold surface was characterized by cyclic voltammetry. From these results, a quantitative model describing the relationship between ELP effective surface coverage as a function of the mean hydrophobicity and mass loading was elucidated, illustrating the ability to precisely control surface properties by tuning the ELP sequence. In addition, strategies for controlling surface-bound ELP assembly and properties will be discussed. Ultimately, our work demonstrates that controlling the assembly and ELP configuration on the solid surface leads to more favorable electrochemical sensing capacity.

Petroleum pitch-derived porous carbon as a metal-free catalyst for direct propane dehydrogenation to propylene

Propane dehydrogenation (PDH), as one of the most promising strategies for propylene synthesis, has attracted tremendous attention with the increase of shale gas exploitation. The exploration of green and sustainable catalytic materials to replace the high-price (Pt-Sn/Al2O3) and environmentally unfavorable (Cr2O3/Al2O3) catalysts will drive the rapid development of PDH technology. Porous carbon-based materials have been proposed as ideal PDH catalysts due to their abundant surface quinone/ketone CO groups for C-H bond activation and well-developed pore structures for mass transfer. However, the facile preparation of carbon-based catalysts with controllable surface properties and unique architectures remains a challenge. And the structure-function relationship of carbon-based catalysts in PDH is also under debate. Herein, we report a simple and efficient synthetic method to prepare the porous carbon-based PDH catalysts with cheap and readily available petroleum pitch as carbon source. The surface chemical properties and architectures of the porous carbon-based catalysts can be precisely tailored by varying the activation temperature during the synthesis process. Various characterizations including X-ray photoelectron spectra, temperature-programmed pyrolysis curves, thermogravimetric analysis and morphology observations clarify that the plentiful surface quinone/ketone CO groups and appropriate adsorption/desorption strengths of reactant/products derived from the great specific surface area are vital factors that guarantee the excellent C-H bond activation capability (propane conversion 45.6%) and alkenes selectivity (73.9%, propylene and ethylene) of the petroleum pitch-derived porous carbon catalyst. This work not only provides a promising alternative catalyst for the PDH process but also enriches the application fields of the carbon-based catalysts.