Mo-Doped Cerium Gadolinium Oxide as Environmentally Sustainable Yellow Pigments

Mo-doped Gd₁Ce_1–<i>x</i>O_3.5+<i>Y</i> (where <i>x</i> ranged from 0 to 0.3) oxides were synthesized as inorganic yellow pigments, which are benign and sustainable. The pigments exhibited good yellow color, with the yellowness value using the CIELAB 1976 system being around 39. In comparison to the existing reports on benign yellow pigments, which have been synthesized using high temperature calcination routes, this pigment has been synthesized through a low temperature sol–gel calcination route. The process also provided for a higher degree of size and shape control, leading to a bandgap of 2.82–2.52 eV. Size reduction to the nano level through the process provided a bottom up approach, where the presence of mineralizers enabled higher mass tone (<i>b</i>* value of around 80) at lower covering thickness. NIR solar reflectance, a measure of the ability of the pigment to contribute to energy savings by reflecting heat generating radiations of sunlight, was as high as 91%. The absence of toxic metal ions coupled with excellent chemical and thermal stabilities makes the developed pigment ideal for coloring plastics meant for children’s toys and ceramic surfaces that would come into immediate contact with human skin, such as bathroom tiles

Cyclic Carbonate: A Recyclable Medium for Zero Discharge Tanning

Cyclic carbonates are currently attracting the worldwide interest of researchers for developing sustainable approaches for a greener environment. Propylene carbonate, one of the cyclic carbonates, was taken as the medium for the chrome tanning process. The said process does not require water input and also consumes a lesser amount of chromium and other tanning auxiliaries than the conventional tanning process. Enhancement of chromium uptake up to nearly 100% w/w was demonstrated through this process. Furthermore, the used cyclic carbonate can be recycled for the next batch of tanning process without any pretreatment, and the developed process enjoys zero discharge of water and chromium. Additionally the propylene carbonate possesses good antimicrobial and antifungal activity, which avoids the usage of any external preservative in the tanning process. Performance of the leathers is shown to be on par with conventionally processed leathers through physical/hand evaluation and morphological analysis. Also, the process is proven to be more economically beneficial than the conventional tanning process

Bright Green Frequency Upconversion in Catechin Based Yb³⁺/Er³⁺ Codoped LaVO₄ Nanorods upon 980 nm Excitation

A series of Yb³⁺–Er³⁺ codoped LaVO₄ phosphors using catechin as a chelating agent and phase director have been prepared by the low temperature hydrothermal synthesis technique. The sample exists in two different crystalline phases, i.e., monoclinic and tetragonal, depending on the concentration of dopants. Structural, optical, and thermal characterizations have been done by using X-ray diffraction, EDX, FE-SEM, UV–vis diffuse reflectance, FTIR, and TGA analysis. Upconversion emission (UC) based imaging and drug delivery systems have been proposed to overcome some significant drawbacks of existing systems. Though fluorides are better hosts for UC, their harmful character has forced researchers to look at alternatives including oxides. The frequency upconversion emission (UC) study upon excitation at 980 nm has been performed in this particular host (<i>m</i>-LaVO₄) which is not an ideal upconverting host. The sample emits bright green color upconversion emission, along with relatively weak emissions in the blue, red, and NIR regions. The nanorod shape of the developed samples has been confirmed by FE-SEM image analysis. The purity of the green color emission has been confirmed by CIE chromaticity diagram which supports its utility in the fabrication of green upconverters

A Novel Approach to Enzymatic Unhairing and Fiber Opening of Skin Using Enzymes Immobilized on Magnetite Nanoparticles

One of the prerequisites for making leather is to remove the inter-fibrillar proteins and noncollagenous materials, such as hair, flesh, etc. These proteinous and nonproteinous materials are removed in several steps, cumulatively known as the pretanning (or beam house) operations. A paradigm shift from chemical- to enzyme-based processes ensured that these noncollagenous materials were removed using enzymatic digestion rather than brutal osmotic forces employing chemicals like lime and sulfide. In order to make sure that a cocktail of enzymes (protease + amylase) have broad application and stability, their immobilization onto matrices that can enable overcoming such drawbacks is essential. This work, taking clues from the catalytic applications of nanoparticle-immobilized enzymes looks at metal oxide nanoparticle-immobilized enzymes for unhairing and fiber opening applications in a facile manner. Iron oxide (Fe₃O₄) nanoparticles have been selected for the present study since metal oxides are proven as an unbeaten matrix for protein tagging. In the present study, a cocktail of protease and amylase (fibrozyme) was used as control, and a nanoparticle-immobilized enzyme cocktail (nanozyme) was used as the experimental sample. Enzyme concentration was fixed as 3% of raw skin weight, while drumming in a stainless steel vessel was looked at as the application method. Nanozyme-treated leather samples were analyzed for their unhairing and fiber opening efficiency. Histological studies, physical strength, and organoleptic studies of control and experimental sample leathers were also carried out. Microstructural analysis based on histopatholgy studies of fibrozyme- and nanozyme-treated tissues exhibited no significant change in tissue morphology, which confirms that nanoparticles did not have any adverse effect on the skin. Scanning electron microscopy (SEM) images of fibrozyme- and nanozyme-treated leathers show the degree of fiber opening, and an energy dispersive X-ray spectrum (EDS) shows the elements present on the skin matrix. This study provides a newer insight for a cleaner, economical, and sustainable method of leather processing