Thermal reactions in mixtures of micron-sized silicon monoxide and titanium monoxide: redox paths overcoming passivation shells

Směsné oxidy a kompozity oxidu TiO2/SiO2 byly intenzivně studovány, zatímco kekich protějšky oxidu titanatého (TiO) a oxidu křemnatého (SiO) stále zůstávají neprozkoumány. Tato studie odhaluje strukturální změny ve zahřátých směsích SiO-TiO. Změny složení ve smísených mikro-částicích TiO a SiO zahřívaných při 1000 ° C byly zkoumány pomocí FTIR, UV-Vis a Ramanovy spektroskopie, rentgenové difrakce a elektronové mikroskopie (SEM a TEM). Ukazuje se, že dochází k úbytku krystalického TiO a tvorbě suboxidů titanu (Ti2.5O3, Ti2O3), rutilu, elementárního křemíku, silicidu titanu Ti5Si3 a amorfních binárních SiOx, TiOx a ternárních nanostruktur SixTiyOz. Tvorba tohoto Si/Ti/O kompozitu je vysvětlena disproprciací SiO, redukcí TiO křemíkem, přenosem kyslíku (redoxní reakce) mezi TiOx a SiOx a kombinací Ti a Si k získání silicidu titanu. Vytvořený Si/Ti/O kompozit absorbuje viditelné světlo a jeho fotokatalytická aktivita ve slunečním záření byla testována na odbarvování methylenové modři (bBlue) a porovnávána s práškem nezahřátého SiO, TiO a Ti5Si3.Silica–titania mixed oxides and composites have been extensively studied, whereas the titanium monoxide (TiO)–silicon monoxide (SiO) counterparts still remain to be explored. Here, we report on structural changes in heated SiO–TiO mixtures. The changes in composition in intimately mixed μm-sized particles of TiO and SiO heated at 1000 °C were examined by FTIR, UV–Vis and Raman spectroscopy, X-ray diffraction and electron (SEM and TEM) microscopy. They are shown to involve depletion of crystalline TiO and formation of titanium suboxides (Ti2.5O3, Ti2O3), rutile, elemental silicon, titanium silicide Ti5Si3 and amorphous binary SiOx, TiOx and ternary SixTiyOz nano-structures. These constituents of the developed Si/Ti/O composite are explained by SiO disproportionation, reduction of TiO by silicon, oxygen transfer (redox) reactions between TiOx and SiOx species and the combination of Ti and Si to obtain titanium silicide. The produced Si/Ti/O composite absorbs visible light and its solar-light photocatalytic activity in decolorization of methylene bBlue is compared to that of the unheated SiO, TiO and Ti5Si3 powders

Recent advances on smart glycoconjugate vaccines in infections and cancer

Vaccination is one of the greatest achievements in biomedical research preventing death and morbidity in many infectious diseases through the induction of pathogen-specific humoral and cellular immune responses. Currently, no effective vaccines are available for pathogens with a highly variable antigenic load, such as the human immunodeficiency virus or to induce cellular T-cell immunity in the fight against cancer. The recent SARS-CoV-2 outbreak has reinforced the relevance of designing smart therapeutic vaccine modalities to ensure public health. Indeed, academic and private companies have ongoing joint efforts to develop novel vaccine prototypes for this virus. Many pathogens are covered by a dense glycan-coat, which form an attractive target for vaccine development. Moreover, many tumor types are characterized by altered glycosylation profiles that are known as “tumor-associated carbohydrate antigens”. Unfortunately, glycans do not provoke a vigorous immune response and generally serve as T-cell-independent antigens, not eliciting protective immunoglobulin G responses nor inducing immunological memory. A close and continuous crosstalk between glycochemists and glycoimmunologists is essential for the successful development of efficient immune modulators. It is clear that this is a key point for the discovery of novel approaches, which could significantly improve our understanding of the immune system. In this review, we discuss the latest advancements in development of vaccines against glycan epitopes to gain selective immune responses and to provide an overview on the role of different immunogenic constructs in improving glycovaccine efficacy