Investigating Permselectivity in PVDF Mixed Matrix Membranes Using Experimental Optimization, Machine Learning Segmentation, and Statistical Forecasting

This research examines the correlation between interfacial characteristics and membrane distillation (MD) performance of copper oxide (Cu) nanoparticle-decorated electrospun carbon nanofibers (CNFs) polyvinylidene fluoride (PVDF) mixed matrix membranes. The membranes were fabricated by a bottom-up phase inversion method to incorporate a range of concentrations of CNF and Cu + CNF particles in the polymer matrix to tune the porosity, crystallinity, and wettability of the membranes. The resultant membranes were tested for their application in desalination by comparing the water vapor transport and salt rejection rates in the presence of Cu and CNF. Our results demonstrated a 64% increase in water vapor flux and a salt rejection rate of over 99.8% with just 1 wt % loading of Cu + CNF in the PVDF matrix. This was attributed to enhanced chemical heterogeneity, porosity, hydrophobicity, and crystallinity that was confirmed by electron microscopy, tensiometry, and scattering techniques. A machine learning segmentation model was trained on electron microscopy images to obtain the spatial distribution of pores in the membrane. An Autoregressive Integrated Moving Average with Explanatory Variable (ARIMAX) statistical time series model was trained on MD experimental data obtained for various membranes to forecast the membrane performance over an extended duration.

Microfluidic nanopaper based analytical device for colorimetric and naked eye determination of cholesterol using the color change of triangular silver nanoprisms

A microfluidic nanopaper-based analytical device (μNPAD) has been prepared for the determination of cholesterol by using triangular silver nanoprisms (T-AgNPrs).

Highly flexible, mesoporous structured, and metallic Cu-doped C/SiO2 nanofibrous membranes for efficient catalytic oxidative elimination of antibiotic pollutants

The development of inorganic membranous catalysts with both large mesopores and superb flexibility is extremely favorable for the enhancement of their catalytic oxidation activity for the degradation of antibiotic pollutants in wastewater via sulfate radical-based advanced oxidation processes; however, there still exists a huge challenge for inorganic materials to simultaneously realize these two properties. Herein, metallic copper-doped carbon/silica nanofibrous membranes (Cu@C/SiO2 NFMs) with large mesopores, superb flexibility, and robust mechanical strength were fabricated through a sol-gel electrospinning and subsequent in situ carbonization reduction method. The synthesized Cu nanoparticles were homogeneously distributed throughout the mesoporous C/SiO2 nanofiber matrix, which enabled the resultant Cu@C/SiO2 NFMs to be applied as heterogeneous catalysts, and their catalytic performance was systematically assessed through activating persulfate for the elimination of tetracycline hydrochloride (TCH) in water. The fabricated Cu@C/SiO2 NFMs provided outstanding catalytic performance towards TCH with a high removal efficiency of 95% in 40 min and a rapid removal speed of 0.054 min-1. Moreover, the membranes could be facilely recycled through being directly separated from water without any post-processing. Such a facile strategy for preparing mesoporous and flexible metal-doped inorganic nanofibrous membranes may offer novel insights for designing new types of heterogeneous catalysts for antibiotic-containing wastewater treatment or other potential applications.

The design, fabrication, and applications of flexible biosensing devices

Flexible biosensors form part of a rapidly growing research field that take advantage of a multidisciplinary approach involving materials, fabrication and design strategies to be able to function at biological interfaces that may be soft, intrinsically curvy, irregular, or elastic. Numerous exciting advancements are being proposed and developed each year towards applications in healthcare, fundamental biomedical research, food safety and environmental monitoring. In order to place these developments in perspective, this review is intended to present an overview on field of flexible biosensor development. We endeavor to show how this subset of the broader field of flexible and wearable devices presents unique characteristics inherent in their design. Initially, a discussion on the structure of flexible biosensors is presented to address the critical issues specific to their design. We then summarize the different materials as substrates that can resist mechanical deformation while retaining their function of the bioreceptors and active elements. Several examples of flexible biosensors are presented based on the different environments in which they may be deployed or on the basis of targeted biological analytes. Challenges and future perspectives pertinent to the current and future stages of development are presented. Through these summaries and discussion, this review is expected to provide insights towards a systematic and fundamental understanding for the fabrication and utilization of flexible biosensors, as well as inspire and improve designs for smart and effective devices in the future.

Synthesis, spectral characterization, molecular modeling, antibacterial and antioxidant activities and stability study of binuclear Pd(II) and Ru(III) complexes with novel bis-[1-(2-[(2-hydroxynaphthalen-1-yl)methylidene]amino}ethyl)-1-ethyl-3-phenylthiourea] ligand: Application to detection of cholesterol

A novel bis-[1-(2-[(2-hydroxynaphthalen-1-yl) methylidene]amino}ethyl)-1-ethyl-3-phenylthiourea] Schiff base (L) and its binuclear palladium and ruthenium complexes have been prepared and characterized by ESI-MS, elemental analysis, NMR (¹H NMR, ¹³C NMR, COSY, NEOSY and HSQC), FT-IR, ATR, UV-Visible spectra, TGA measurements, conductivity and cyclic voltammetry. The experimental results and the molecular parameters calculated using DFT method revealed a square planar geometry around Pd and octahedral geometry around ruthenium metal. The antibacterial activity of the ligand L and its complexes was evaluated against different human bacteria. In addition, the formation constants of the synthesized Schiff base-metal complexes and the systems formed with these chelates and cholesterol were estimated using spectrophotometric technique. The detection of cholesterol using novel Pd and Ru Schiff base complexes was studied using fluorometric method, and the measurements showed that the sensitive fluorometric response towards cholesterol analysis was determined using palladium complex. The limit of detection (LOD) of cholesterol calculated using this complex (4.6 μM) is lower (better) than LOD found using ruthenium complex (19.1 μM) and different compounds previously published around linear range of 0-5 mM.

Cu2(OH)PO4/reduced graphene oxide nanocomposites for enhanced photocatalytic degradation of 2,4-dichlorophenol under infrared light irradiation

Sparked by the growing environmental crises, photocatalytic degradation of chlorophenols with inexhaustible solar energy is expected to be converted into actual applications. Here, we report the preparation of the nanocomposite of Cu2(OH)PO4 and reduced graphene oxide (Cu2(OH)PO4/rGO) through a one-step hydrothermal method and examined its infrared-light photocatalytic activity in the degradation of 2,4-dichlorophenol (2,4-DCP). As evidenced by the absorption spectra and the degradation of 2,4-DCP, Cu2(OH)PO4/rGO exhibited enhanced infrared light-driven photocatalytic activity compared to pure Cu2(OH)PO4 and was very stable even after repeated cycling. More importantly, the introduction of hydrogen peroxide (H2O2) could combine the photocatalytic and photo-Fenton effects into one reaction system and maximize the infrared light photocatalytic efficiency. Typically, the rate constant of Cu2(OH)PO4/rGO and H2O2 was more than 6.25 times higher than that of only Cu2(OH)PO4/rGO, and almost 10 times greater than the value for pure Cu2(OH)PO4. Further, a plausible mechanism for the enhanced photocatalytic properties of Cu2(OH)PO4/rGO has been discussed. These findings may help the development of novel hybrid photocatalysts with enhanced infrared light photocatalytic activity for applications in the treatment of chlorophenol-contaminated wastewater.

Flexible carbon nanofiber electrodes for a lead zirconate titanate nanogenerator

The performance and stability of flexible carbon nanofiber (CNF) electrodes were investigated for a lead zirconate titanate (PZT) nanogenerator.