Joydip Mondal

Zeolitic imidazolate frameworks (ZIFs) have emerged as promising candidates for high O₂ adsorption capacity, O₂/N₂ selectivity and cyclability due to their tunable chemical and structural properties governed by the selection of organic ligands, metal centres and synthesis methods. Therefore, this research engineers ZIF-7, ZIF-8, ZIF-62 and their mixed-metal derivatives containing cobalt (Co) or iron (Fe) (ZIF-8-derived Fe-mIM where applicable) to improve O₂ adsorption. Because performance metrics trade off, no single ZIF maximised all objectives, and application-specific leads were identified. The highest O₂ capacity was delivered by ZIF-8(Zn : Co = 90 : 10)-MS, reaching 0.35 mmol g⁻¹ with selectivity of 2.01, and 9.9% decrease over 3 cycles. The greatest selectivity was achieved by ZIF-8-derived Fe-mIM material (Zn : Fe = 0 : 100)-MS, giving selectivity of 2.60 at a low adsorption of 0.09 mmol g⁻¹ and 9.6% loss over 3 cycles. The most robust 3-cycle performance was observed for ZIF-8-US, which retained capacity with 0.5% loss while providing 0.26 mmol g⁻¹ and selectivity of 1.06. For a balanced generalist over 3 cycles, ZIF-62-US offered the strongest overall combination, providing 0.34 mmol g⁻¹, selectivity of 1.01, and 1.3% loss. These results underscore the delicate balance among O₂ adsorption performance with structural integrity, coordination chemistry, adsorption characteristics, and cyclability in ZIFs shaped by organic ligand, metal centres, and synthesis method choices.

The molecules possessing triazine and tetrazine moieties belong to a special class of heterocyclic compounds. Both triazines and tetrazines are building blocks and have provided a new dimension to the design of biologically important organic molecules. Several of their derivatives with fine-tuned electronic properties have been identified as multifunctional, adaptable, switchable, remarkably antifungal, anticancer, antiviral, antitumor, cardiotonic, anti-HIV, analgesic, anti-protozoal, etc. The objective of this review is to comprehensively describe the recent developments in synthesis, coordination properties, and various applications of triazine and tetrazine molecules. The rich literature demonstrates various synthetic routes for a variety of triazines and tetrazines through microwave-assisted, solid-phase, metal-based, [4+2] cycloaddition, and multicomponent one-pot reactions. Synthetic approaches contain linear, angular, and fused triazine and tetrazine heterocycles through a combinatorial method. Notably, the triazines and tetrazines undergo a variety of organic transformations, including electrophilic addition, coupling, nucleophilic displacement, and intramolecular cyclization. The mechanistic aspects of these heterocycles are discussed in a detailed way. The bioorthogonal application of these polyazines with various strained alkenes and alkynes provides a new prospect for investigations in chemical biology. This review systematically encapsulates the recent developments and challenges in the synthesis and possible potential applications of various triazine and tetrazine systems. Graphical Abstract

Acoustic cavitation (or the formation of bubbles using acoustic or ultrasound-based devices) has been extensively exploited for biological applications in the form of bioprocessing and drug delivery/uptake. However, the governing parameters behind the several physical effects induced by cavitation are generally lacking in quantity in terms of suitable operating parameters of ultrasonic units. This review elaborates the current gaps in this realm and summarizes suitable investigative tools to explore the shear generated during cavitation. The underlying physics behind these events are also discussed. Furthermore, current advances of acoustic shear on biological specimens as well as future prospects of this cavitation-induced shear are also described.

Multiple bubble interactions in initially quiescent liquid are often accompanied by generation of jets, shockwaves and light. At cryogenic temperature (< 123 K) when certain materials (particularly bcc-type) become brittle, such afore-mentioned physical effects can be effective in disintegrating them to smaller fragments. CFD techniques based on direct numerical simulations can help to understand this phenomenon that may benefit nanotechnology-based industries and oil-gas exploration-firms working with air-gun arrays. In this paper, multiple bubble-pairs are simulated in a co-centric manner around a centrally located solid target (5 mm radius). The ambient fluid is liquid nitrogen (77 K) and the bubbles are gaseous nitrogen (87 K). 2D numerical simulation using the VOF method in compressible domain is carried out neglecting the effect of phase change and gravity. The stand-off distance between the solid target and bubble-pairs are varied systematically and its influence on the fluid-dynamic effects (e.g. pressure shockwave & jets) are compared. Initial calculations suggest that for stand-off distance of 0.93 mm, shockwaves measure above 10 times the ambient pressure and liquid jet speeds around 30 m/s in cryogenic environment, at multiple locations very close to the solid target. These consecutive physical impacts can foster ample liquid-hammer pressures, making it promising for solid wear at 77 K when juxtaposed against room-temperature cases.

Two-phase flow in cryogenic system¹ is very common due to unavoidable heat inleak and low boiling points of cryogenic fluids. Although it may be detrimental to transfer lines, fluid handling equipment, etc., the flow conditions can be utilized for controlled erosion and particle fragmentation instead. In this study, the erosive effects possible during vapor formation are identified for a circular material target placed in the vicinity of bubble-array in a cryogenic environment (gaseous nitrogen or GN2 bubbles in liquid nitrogen or LN2). The physical effects observed during the interaction include shockwaves due to fast bubble-expansion, liquid jet-hammering, and lateral shear of the surface. The flow-field analysis is conducted to evaluate the typical magnitudes of these phenomena. Results indicate fluid-hammer pressure of 33 MPa as well as jet impact velocity of 48 m/s, which may be sufficient to dent BCC metals at LN2 temperatures. Further, the values obtained for air bubbles in water are also compared. This study can help to understand better the erosive effects of multiple bubbles for prospective applications.