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Zeolitic imidazolate framework (ZIF) materials are thermally and chemically stable, and suitable for many possible applications, including chemical sensors, gas separation, energy storage, catalysis, etc. However, the conventional synthesis techniques of ZIFs need to be revisited to make them time-efficient and cost-effective with better process control. Here we show the potential of microfluidics for the synthesis of ZIF, resulting in improved porosity, surface morphology and stability. Four distinct operating conditions were used to synthesize ZIF-67 metal–organic framework, viz. sonication at room temperature, without sonication at room temperature, 70 °C, and 120 °C, using a fully continuous microfluidic technique incorporating a T-type micromixer connected to a helical microfluidic flow reactor (HMFR). ZIF-67 is synthesized in methanol at a constant metal salt/ligand ratio of 1:8 without adding modulators such as capping agents and surfactants. We used a T-micromixer coupled with a helically wound microfluidic tubing for the first time to synthesize the crystalline ZIF-67 resulting in synthesis of high quality ZIF through the continuous and time-effective processing route. The samples were characterized using FESEM, TEM, XPS, XRD, BET, TGA and FTIR which showed remarkable characteristics of ZIF-67 useful for many applications. [ABSTRACT FROM AUTHOR]

Bimetallic MOFs offer many advantageous properties rather than monometallic MOFs useful for variety of applications including energy storage and conversion, catalysis, gas separation, sensing, etc. Desired morphology with precise control of crystal size is of utmost importance for specific applications. Microfluidics-incorporated continuous synthesis is demonstrated for bimetallic ZIF-8/67 exhibiting significant nanocrystallinity, porosity and surface area. The microfluidic approach of synthesizing MOF is found very time-efficient in comparison with the conventional techniques. Bimetallic ZIF-8/67 samples were synthesized at different reaction conditions, without adding capping agents and modulators, followed by sophisticated characterization techniques including powder X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, Brunauer–Emmett–Teller analysis and Fourier transform infrared spectroscopy. [ABSTRACT FROM AUTHOR]

Shielding of the specific body organ using the biocompatible material helps preventing direct exposure of that part to the foreign entities responsible for infections. Here we show the potential of the A2 milk protein recovered from the milk of cow from Indian origin for possible prevention of the direct exposure to other foreign molecules. We measured the surface pressure of the monolayers of different types of protein samples using Langmuir isotherm experiments. The surface pressure measurements for the monolayer of four types of protein macromolecules have been carried out using the Wilhelmy plate micro pressure sensor. We studied the self-organization of different protein macromolecules and their monolayer compression characteristics. The electrochemical behaviour is studied using electrochemical impedance spectroscopy. We found the highest surface pressure for the monolayer of A2 protein. Further, it is also found that A2 protein exhibited the highest surface activity amongst the other proteins. This property can be effectively used for making the envelope of the A2 protein surrounding the targeted entity. [ABSTRACT FROM AUTHOR]

Abundant applications of silica nanoparticles (SiNPs) have motivated many research groups for silica nanoparticles synthesis with tuned properties. Here we show the formation of SiNPs using the top-down method in a wet attrition mill with effective use of surfactants sodium laurylsulfate (SLS) and Tween-80. The attrition milling was facilitated by using zirconium beads as milling media. The effects of surfactant concentration on particle size distribution have been studied with a particle size analyzer using the dynamic light scattering technique (DLS). The optimum conditions for wet milling with surfactant concentration were evaluated experimentally. The field emission scanning electron microscopy (FE-SEM) analysis confirmed particle size and particle shape. The energy-dispersive X-ray spectroscopy (EDX) exhibited the presence of silicon and oxygen as elemental constituents of SiNPs. The FEG - Transmission electron microscope and HR-TEM analysis identified SiNPs of spherical shape in the size range from 21 nm to 46 nm. The X-ray diffraction (XRD) peaks revealed the presence of SiNPs polycrystallite size as 35.54 nm and 40.63 nm for 5 wt % Tween-80 and 5 wt% SLS, respectively. The selected area electron diffraction (SAED) pattern analysis exhibited a polycrystalline structure of SiNPs. Fourier transform infrared spectroscopy (FTIR) peaks confirmed the purity of SiNPs and the presence of Si-O bond. The foam formation and foam stability were analyzed to explore the effects of foam formation on the wet milling process. These experimentations propose the effective use of surfactants in the milling method for the production of SiNPs. Graphical Abstract [ABSTRACT FROM AUTHOR]

Many applications of silica aerogel require desired mechanical and structural properties. Glycerol and polyethylene glycol were used for the synthesis of silica aerogel to improve mechanical and structural properties. Methyltrimethoxysilane was used as a precursor in various concentrations to explore the effects on the properties of silica aerogel. Polyethylene glycol-based aerogel exhibited high tensile stress-withstanding capacity, at the same time high surface hydrophobicity with contact angle 148°. The swelling and de-swelling behavior of aerogel were also analyzed. This lightweight material has low bulk density, which is found to be affected by the presence of additives. The density of aerogel varied from 0.07 to 0.09 g/cm3 with increasing amount of additive. Polyethylene glycol is found to be very effective additive especially for the improvement of the mechanical properties of aerogel, as it has exhibited the breakdown at 21,924.6 N/m2 with elongation of 0.8 cm. The aerogel samples were analyzed for their surface hydrophobicity and thermogravimetry analysis. The elemental analysis of aerogel confirmed the purity of aerogel while thermogravimetric analysis and differential thermogravimetric analysis revealed its high thermal stability up to 519 °C. [ABSTRACT FROM AUTHOR]

Dispersing nanoparticles in the liquid significantly alters the transport properties of the resulting fluids. Conventional coolants such as water and oils have comparatively low thermal conductivities and offer somewhat limited heat transfer coefficients to accomplish the typical cooling applications. Dispersed nanoparticles with higher thermal conductivity provide better transport properties leading to enhanced heat transfer coefficients in many devices of different size. Nanofluids which contain nanoparticles dispersed in continuous liquid phase provide many promising properties as compared to conventional fluids. In the present work, we prepared magnetic nanoparticles by the co-precipitation, followed by ultrasonication and coating with oleic acid, which were ultimately dispersed in kerosene as a carrier fluid. The agglomeration of the coated particles was thus prevented to improve their stability. The samples were analysed with various sophisticated techniques such as high-resolution transmission electron microscopy, field emission scanning electron microscopy, dynamic light scattering, zeta potential, X-ray diffraction, Fourier transform infrared spectra, thermogravimetric analysis, rheometry, and superconducting quantum interference device. The coated magnetic nanoparticles showed weak attraction force and offered reasonable colloidal stability of the nanofluid. [ABSTRACT FROM AUTHOR]

Lab-on-a-Chip based microfluidic devices facilitate simple, and continuous separation of nanoparticles in well-controlled and cost-effective manner. We fabricated Y-shaped microchannels with different bifurcation angles of the outlet legs for magnetic field-assisted separation. The bifurcation angles have shown the direct effect on the hydrodynamics at the bifurcation point. As a result, based on the external force, the migration of the particles from the main stream to the wall was observed. Trapping of particles were also observed at higher flow rates with different dispersion media. Bifurcation angles of microchannels at junction were θ = 40°, θ = 78° and θ = 90°. Separability of the magnetic nanoparticles has been found to be affected by the flow rates and the channel geometry. Trapping of the particles, and release from the trapped region were also observed which can be used for selective particles release for micro-reactor or micro-separator designs. [ABSTRACT FROM AUTHOR]

This paper reports an ingenious colorimetric sensor probe for the detection of Cd2+ ions using cysteamine functionalized gold nanoparticles cross-linked with DL-glyceraldehyde (DL-G-CA-Au NPs). Rapid aggregation in DL-G-CA-Au NPs was observed by adding Cd2+ ions at PBS buffer pH 7.0, which results in an immediate color change of the solution from red to blue. A red-shift in the wavelength of absorption peak was measured from 520 to 736 nm using UV-visible spectroscopy. The surface functionalization and aggregation of Au NPs were also characterized by recoding FI-IR and DSL data. The colorimetric probe was analyzed in the concentration of Cd2+ ions ranging from 0.05 to 500 μM, and a good linearity was observed towards the lower concentration levels with a coefficient of correlation R2 = 0.9862. The limit of detection was found to be 21 nM, which best describes its superior performance over other reported colorimetric probes. Furthermore, the performance of the probe was not influenced by other metal ions, and the stability of DL-G-CA-Au NPs was maintained even after 30 days. The proposed method was successfully applied to various water samples collected from the environment, and an accuracy ≥ 98% was achieved. [ABSTRACT FROM AUTHOR]