Rakesh K. Behera

concentrations of 180 and 12 μM, respectively. HS analysis quantified non-covalent interatomic contacts between the atoms and fluoride ions, revealing that 1-TBAF contributed a maximum of 19.2% of all atoms⋯F contacts to the HS. Density functional theory studies were carried out on the 1-TBAF, 2-TBAF, and 3-TBAF crystal systems, and the band structure and total density of states of the systems were evaluated. The optical response of 2-TBAF was also investigated.

BACKGROUND: Polylactic acid (PLA) has been extensively used in tissue engineering. However, poor mechanical properties and low cell affinity have limited its pertinence in load bearing bone tissue regeneration (BTR) devices. OBJECTIVE: Augmenting PLA with β-Tricalcium Phosphate (β-TCP), a calcium phosphate-based ceramic, could potentially improve its mechanical properties and enhance its osteogenic potential. METHODS: Gels of PLA and β-TCP were prepared of different % w/w ratios through polymer dissolution in acetone, after which polymer-ceramic membranes were synthesized using the gel casting workflow and subjected to characterization. RESULTS: Gel-cast polymer-ceramic constructs were associated with significantly higher osteogenic capacity and calcium deposition in differentiated osteoblasts compared to pure polymer counterparts. Immunocytochemistry revealed cell spreading over the gel-cast membrane surfaces, characterized by trapezoidal morphology, distinct rounded nuclei, and well-aligned actin filaments. However, groups with higher ceramic loading expressed significantly higher levels of osteogenic markers relative to pure PLA membranes. Rule of mixtures and finite element models indicated an increase in theoretical mechanical strength with an increase in β-TCP concentration. CONCLUSION: This study potentiates the use of PLA/β-TCP composites in load bearing BTR applications and the ability to be used as customized patient-specific shape memory membranes in guided bone regeneration.

Halide perovskite nanocrystals have recently emerged as high-performance light-harvesting materials. They are also extensively studied for the fabrication of both light-emitting and photovoltaic devices. In comparison, their implementation as photocatalysts to trigger different organic reactions is limited. To add more diversity in catalysis, herein, different shapes and heterostructures of CsPbBr 3 perovskite polyhedral nanocrystals are explored for visible-light-mediated room temperature photocatalytic C sp 3 –H bond-activated alkylation of cyclic ether using feedstock α,β-unsaturated acids as the keto-alkyl source. It started with the decarboxylative coupling of cinnamic acid at the α-position of tetrahydrofuran (THF) and extended to several derivatives. The facets of nanocrystals matter, and hence, differently shaped nanocrystals showed variable rates of catalytic activities. With density functional theory calculation, the surface-adsorption-induced charge carrier transfer mechanism to facilitate such reactions is established. Different semiconductors and noble metal heterostructures that quenched the emission are also compared, and their inactiveness in catalysis was also correlated to the proposed mechanism. Combining all these observations, the roles of light, catalytic surfaces, oxygen, the nature of hosts, and coupling with other material heterostructures are analyzed in detail and reported. Such reactions with C sp 3 –H bond activation can lead to complex chemical scaffolds, unveiling an underexplored domain of heterogeneous photocatalytic organic reactions for C sp 3 –C sp 3 cross-coupling.

Abstract There is an ever‐evolving need of customized, anatomic‐specific grafting materials for bone regeneration. More specifically, biocompatible and osteoconductive materials, that may be configured dynamically to fit and fill defects, through the application of an external stimulus. The objective of this study was to establish a basis for the development of direct inkjet writing (DIW)‐based shape memory polymer‐ceramic composites for bone tissue regeneration applications and to establish material behavior under thermomechanical loading. Polymer‐ceramic (polylactic acid [PLA]/β‐tricalcium phosphate [β‐TCP]) colloidal gels were prepared of different w/w ratios (90/10, 80/20, 70/30, 60/40, and 50/50) through polymer dissolution in acetone (15% w/v). Cytocompatibility was analyzed through Presto Blue assays. Rheological properties of the colloidal gels were measured to determine shear‐thinning capabilities. Gels were then extruded through a custom‐built DIW printer. Space filling constructs of the gels were printed and subjected to thermomechanical characterization to measure shape fixity ( R f ) and shape recovery ( R r ) ratios through five successive shape memory cycles. The polymer‐ceramic composite gels exhibited shear‐thinning capabilities for extrusion through a nozzle for DIW. A significant increase in cellular viability was observed with the addition of β‐TCP particles within the polymer matrix relative to pure PLA. Shape memory effect in the printed constructs was repeatable up to 4 cycles followed by permanent deformation. While further research on scaffold macro‐/micro‐geometries, and engineered porosities are warranted, this proof‐of‐concept study suggested suitability of this polymer‐ceramic material and the DIW 3D printing workflow for the production of customized, patient specific constructs for bone tissue engineering.

The cube shape of orthorhombic phase CsPbBr 3 nanocrystals possesses the ability of selective facet packing that leads to 1D, 2D, and 3D nanostructures. In solution, their transformation with linear one-dimensional packing to nanorods/nanowires is extensively studied. Here, multifacet coupling in two directions of the truncated cube nanocrystals to rod couples and then to single-crystalline rectangular rods is reported. With extensive high-resolution transmission electron microscopy image analysis, length and width directions of these nanorods are derived. For the seed cube structures, finding {110} and {002} facets has remained difficult as these possess the hexahedron symmetry and their size remains smaller; however, for nanorods, these planes and the ⟨110⟩ and ⟨001⟩ directions are clearly identified. From nanocrystal to nanorod formation, the alignment directions are observed as random (as shown in the abstract graphic), and this could vary from one to the other rods obtained in the same batch of samples. Moreover, seed nanocrystal connections are derived here as not random and are rather induced by addition of the calculated amount of additional Pb(II). The same has also been extended to nanocubes obtained from different literature methods. It is predicted that a Pb-bromide buffer octahedra layer was created to connect two cubes, and this can connect along one, two, or even more facets of cubes simultaneously to connect other cubes and form different nanostructures. Hence, these results here provide some basic fundamentals of seed cube connections, the driving force to connect those, trapping the intermediate to visualize their alignments for attachments, and identifying and establishing the orthorhombic ⟨110⟩ and ⟨001⟩ directions of the length and width of CsPbBr 3 nanostructures.