Glass,Ceramic, Polymeric,and Composite Scaffolds with Multiscale Porosity for Bone Tissue Engineering

Porosity affects performance of scaffolds for bone tissue engineering both in vitro and in vivo. Macropores (i.e., pores with a diameter >100 μm) are essential for cellular infiltration; micropores (i.e., pores with a diameter of 1–10 μm) promote cell adhesion and facilitate nutrient absorption. Scaffolds containing both macropores and micropores exploit the advantages of both pore sizes and have excellent osteogenic properties. Nanopores (i.e., pores with a diameter of 1–50 nm) can be included as well, to improve cell–material interactions by further enhancing the surface area of the scaffold. This article reviews fabrication techniques and properties of scaffolds with multiscale porosity, focusing on glass, ceramic, polymeric, and composite scaffolds. After discussing the structure of bone and how it inspired scaffolds for bone tissue engineering, pore nomenclature is introduced. Then, the techniques used to induce multiscale porosity, the nature of the pores created, and the effects of scaffold porosity on mechanical properties and biological activity of the scaffolds are discussed. The review concludes by providing an outlook for this field, including advancements that are made possible by computational modeling and artificial intelligence.     

Morphological and functional characterization of circulating hemocytes using microscopy techniques

In the present study, Microscopy studies were performed to characterize the blood cells of the mangrove crab Episesarma tetragonum. Three types of hemocytes were observed: granulocytes, semi‐granulocytes, and hyalinocytes or agranulocytes. Hyalinocytes have a distinguished nucleus surrounded by the cytoplasm, and a peculiar cell type was present throughout the cytosol, lysosomes with hemocyte types (granules) stained red (pink). Giemsa staining was used to differentiate between the large and small hemocytes. Ehrlich's staining was used to differentiate granule‐containing cells in acidophils (55%), basophils (44%), and neutrophils (<1%). Periodic acid–Schiff staining was used to identify the sugar molecules in the cytoplasm. Cell‐mediated immune reactions including phagocytosis, encapsulation, agglutination, and peroxidase‐mediated cell adhesion are the functions of hemocytes. Agglutination reaction involves both kind of cells involved in yeast and heme‐agglutination responses in invertebrates. The beta glucan outer layer of yeast cells was recognized by hemocyte receptors. Human RBC cells were agglutinated via granulocytes. E. tetragonum hemocytes are an important animal model for studying both ultrastructural and functional activity of circulating cells. In addition, E. tetragonum hemocytes exhibited excellent antibacterial and antibiofilm activities were studied through plating and microplate assays. Biofilm inhibition was also visualized through changes in biochemical assays and morphological variations were visualized through levels in in situ microscopy analysis.     

Hemodialysis in a patient with severe hemophilia A and factor VIII inhibitor

Hemophilia A is a hereditary X‐linked recessive disease caused by mutations in the gene encoding factor VIII (FVIII), occurring in 1 out of 10,000 persons. Life expectancy and quality of life have dramatically improved recently in patients with hemophilia. Chronic kidney disease and need for renal replacement therapy in these patients are rare. The development of inhibitors to FVIII is the most serious complication of hemophilia and makes treatment of bleeds very challenging. We describe here a 28‐year‐old male patient with severe hemophilia A with presence of factor VIII inhibitor, who had end stage renal disease. Central venous access device was inserted along with infusion of factor eight inhibitor bypass activity before and after the procedure. He is currently on thrice weekly hemodialysis and doing well for 6 months without bleeding episodes. To our knowledge, hemophilia A with factor VIII inhibitor managed with hemodialysis has not been reported so far.     

Investigations on the performance and exhaust emissions of a diesel engine using preheated waste frying oil as fuel

In the present experimental investigation, waste frying oil a non-edible vegetable oil was used as an alternative fuel for diesel engine. The high viscosity of the waste frying oil was reduced by preheating. The properties of waste frying oil such as viscosity, density, calorific value and flash point were determined. The effect of temperature on the viscosity of waste frying oil was evaluated. It was determined that the waste frying oil requires a heating temperature of 135 °C to bring down its viscosity to that of diesel at 30 °C. The performance and exhaust emissions of a single cylinder diesel engine was evaluated using diesel, waste frying oil (without preheating) and waste frying oil preheated to two different inlet temperatures (75 and 135 °C). The engine performance was improved and the CO and smoke emissions were reduced using preheated waste frying oil. It was concluded from the results of the experimental investigation that the waste frying oil preheated to 135 °C could be used as a diesel fuel substitute for short-term engine operation.     

Structural properties of V2O5 thin films prepared by vacuum evaporation

Vanadium pentoxide (V₂O₅) films were deposited on glass substrates by vacuum evaporation technique at various deposition temperatures (T_s) viz., 300, 473, 573, 623 and 673 K. The structural and microstructural properties of the films are analyzed using XRD and Raman scattering measurements. X-ray characterization revealed the films deposited at T_s473 K are amorphous and the film deposited at T_s573 K are polycrystalline with orthorhombic symmetry. The corrected lattice constant values are determined from Nelson-Riely plots. The lattice constants “a” and “c” are found to decrease with increase in the deposition temperature, which may be attributed to the increase in non-stoichiometry. Change in the preferred orientation is observed for films deposited at substrate temperatures 623 K which is likely to be governed by the recrystallization process. Various structural parameters such as lattice constants, grain size, and microstrain and dislocation density are determined and the influence of deposition temperature on the structural parameters are discussed.     

Surface‐Confined Heterometallic Molecular Dyads: Merging the Optical and Electronic Properties of Fe,Ru, and Os Terpyridyl Complexes

Molecular assemblies of surface‐confined heterometallic molecular dyads (SURHMDs) composed of optically rich and redox‐active Fe(pytpy)₂·2PF₆ (Fe‐PT), Ru(pytpy)₂·2PF₆ (Ru‐PT) and Os(pytpy)₂·2PF₆ (Os‐PT) pytpy = 4′‐(4‐pyridyl)‐2,2′:6′,2″‐terpyridyl] complexes are fabricated via bottom‐up approach on SiO_x based solid supports. Pairing of the two different metal‐organic complexes at a single platform results in significant enlargement of the optical window (λ = 400–800 nm), which can be of interest for potential applications. The use of the Cu‐based linker ensures intramolecular electronic communication between these complexes. In addition, SURHMDs are electrochemically stable under large numbers of read‐write cycles (10³) and exhibit multiple redox states at relatively low potentials (<1.2 V). Moreover, an electrochemical input at controlled potentials creates a mixed‐valence multicomponent system.