Development of sers substrates based on nanoparticles obtained by pulsed laser ablation

SERS spectroscopy is an effective method for the determination of organic and biological compounds, which finds its place in many areas of human life: the analysis of works of art and food 24 YOUNG SCIENTISTS SESSION SESSION Y products, the identification of drugs and drugs, the study of biological structures, incl. at the cellular level. The creation of simple and effective SERS substrates is an urgent task in the development of this method. This paper presents the results of a study of SERS substrates based on gold nanoparticles (NPs). Gold NPs were obtained by pulsed laser ablation of an Au metal target in alcohol using a Nd:YAG laser (1064 nm, 7 ns, 150 mJ). The resulting colloidal solution was applied onto glass substrates by the drop method, varying the number of layers. The SERS characteristics were studied using a model dye rhodamine 6G using Renishaw inVia Basis Raman microscope. The samples were excited in the region of surface plasmon resonance of gold by laser radiation of 532 nm. The results of the study showed that with an increase in the number of deposited layers up to 5, the intensity of the Raman scattering of the dye increases linearly. With a further increase in the number of layers, the signal saturates. This data correlates with SEM data. At the beginning, an increase in the packing density of NPs in the plane of the substrate is observed. Accordingly, the number of "hot spots" increases, which contribute to the amplification of the signal. Further, the homogeneity of the NP layer deteriorates, and large bulk agglomerates appear. Thus, we have developed a simple method for obtaining SERS substrates, which made it possible to increase the signal intensity up to three orders of magnitude

Bone remodeling markers after experimental augmentation of trabecular bone defects with resorbable and non-resorbable osteoplastic materials in rabbits

To study the effect of bone defect augmentation on the dynamics of bone remodeling markers. Material and methods The effect of resorbable xenoplastic material (RXM), synthetic beta-tricalcium phosphate (b-TCP), porous titanium implant (PTI) and nanostructured carbon implant (NCI) on the markers of bone remodeling (osteocalcin, OC; bone alkaline phosphatase, BALP; C-terminal telopeptide of type I collagen, CTX-1) and inflammation marker (C-reactive protein, CRP) was investigated using bone defect model in rabbits. 24 animals were divided into 4 groups (n = 6 in each group) according to the type of osteoplastic material. Control group (n = 6) was without augmentation. An impression fracture of the proximal tibia was modeled. Blood samples were taken on days 1, 3, 7, 14, 45, 90, 180 after surgery. Results CTX-1was not detected in the control, b-TCP, PTI, and RXM groups after 90 days, but in the NCI group CTX-1 remained elevated until the end of the study. OC in the control, b-TCP, PTI groups reached a maximum at 14-45 days. No significant increase in OC was found in the NCI group. The BALP in the control group peaked at 90 days. In the b-TCP and PTI groups the concentration of BALP increased more rapidly. The dynamics of CRP in the RXM, b-TCP and PTI groups was similar to the dynamics in the control group, in the NCI group an increased level of CRP remained until the end of the study. Conclusion When a bone defect was augmented with both resorbable b-TCP and nonresorbable PTI, high osteogenesis activity and low osteoresorption activity were detected. The use of xenoplastic material did not reveal any advantages in comparison with surgery performed without augmentation. An increase in osteoresorption and a low level of osteogenesis were found by using NCI. © Yildiz K., Yildiz V., 2020

The influence of bone substitute material on mechanical properties of trabecular bone in augmentation of intra-articular impression fractures. Experimental study

The purpose was to evaluate the effect of bone substitute materials on mechanical properties of trabecular bone adjacent to the joint. Material and methods A total of 21 female chinchilla rabbits weighing 3-3.5 kg was used for the experimental study. A bilateral impression fracture was simulated in the medial tibial condyle and surgically augmented with one of the bone substitution materials: beta-tricalcium phosphate, xenoplastic material and carbon nanostructures. The animals were sacrificed at 6, 12 and 24 weeks postsurgery. Uniaxial compression test was performed to determine mechanical properties of the tibial fragments. Bone microstructure was evaluated with scanning electron microscopy. Statistical data analysis was performed with nonparametric tests. Results Beta-tricalcium phosphate augmentation of the bone interface led to slow resorption accompanied by formation of adequate high-grade bone tissue with mechanical properties gradually increasing with greater observation time that indicated to the bone substitute integrated well with the host bone of the impression bone defect. Xenoplastic augmentation resulted in rapid resorption accompanied by formation of immature bone with mechanical properties declining at 6 to 12 weeks of observation. Carbon nanostructure augmentation of the bone interface caused perifocal bone resorption and absence of osteointegration with mechanical properties declining at 12 to 25 weeks of observation. © Gilev M.V., Zaytsev D.V., Izmodenova M.Y., Kiseleva D.V., Volokitina E.A., 2018

The influence of bone substitute material on mechanical properties of trabecular bone in augmentation of intra-articular impression fractures. Experimental study

The purpose was to evaluate the effect of bone substitute materials on mechanical properties of trabecular bone adjacent to the joint. Material and methods A total of 21 female chinchilla rabbits weighing 3-3.5 kg was used for the experimental study. A bilateral impression fracture was simulated in the medial tibial condyle and surgically augmented with one of the bone substitution materials: beta-tricalcium phosphate, xenoplastic material and carbon nanostructures. The animals were sacrificed at 6, 12 and 24 weeks postsurgery. Uniaxial compression test was performed to determine mechanical properties of the tibial fragments. Bone microstructure was evaluated with scanning electron microscopy. Statistical data analysis was performed with nonparametric tests. Results Beta-tricalcium phosphate augmentation of the bone interface led to slow resorption accompanied by formation of adequate high-grade bone tissue with mechanical properties gradually increasing with greater observation time that indicated to the bone substitute integrated well with the host bone of the impression bone defect. Xenoplastic augmentation resulted in rapid resorption accompanied by formation of immature bone with mechanical properties declining at 6 to 12 weeks of observation. Carbon nanostructure augmentation of the bone interface caused perifocal bone resorption and absence of osteointegration with mechanical properties declining at 12 to 25 weeks of observation

The effect of Gd addition on the kinetics of α₂→γ transformation in γ-TiAl based alloys

The effect of Gd on the formation of a lamellar structure during ageing of quenched γ-TiAl studied. Ti-47.1Al-1.8Nb-0.5Zr-0.3V-0.001Gd (0.001Gd) and Ti-46.9Al-1.6Nb-0.5Zr-0.5V-0.03Gd (0.03Gd) alloys were quenched from the alpha-phase field and aged at 400–800 °C. After quenching, a small amount of Gd₂TiO₅ particles was found in both alloysbased alloys wa

Investigation of bone tissue mechanical properties in the supra-acetabular region

Introduction The investigation of the trabecular bone strength in the acetabular area and its dependence on age and gender may provide a theoretical basis for the development of implants for bone replacement. The purpose of this study was to determine the mechanical characteristics of the bone tissue in the supra-acetabular region in patients of different age groups. Materials and methods The cadaveric material of 60 patients was studied and included 20 young patients (age range, 18 to 44), 20 middle-aged patients (age range 45 to 59) and 20 elderly patients (age range, 60 to 74). Fragments of bone tissue 3 × 3 × 1.5 cm in size were removed from the supraacetabular region using an osteotome. Cylindrical specimens, 6 mm in diameter and 9 mm high, were produced from these fragments using a crown cutter. All samples were subjected to uniaxial compression at a loading rate of 1 mm/min. Results Comparison of male patients for each of the mechanical parameters did not reveal age differences (p > 0.05). In women of different age groups, the magnitude of elastic deformation was significantly different both by multiple analysis and in pairwise comparison of groups (p 0.05). Discussion The data obtained on the mechanical behavior of the trabecular bone and the values of the strength parameters are explained by the spatial arrangement of the fibers of structural proteins, the cross-linking profile of collagen, the degree of matrix mineralization, the structure of hydroxyapatite, and the amount of bound water. Conclusion In male patients, mechanical characteristics of the bone tissue in the supra-acetabular region do not change significantly with age. In women, the value of elastic deformation increases significantly with age. The maximum tensile strength and modulus of elasticity in women of different ages did not show any changes © Udintseva M.Yu., Zaitsev D.V., Volokitina E.A., Antropova I.P., Kutepov S.M., 202

Cracking of Ti₂AlNb-based alloy after laser beam welding

Crack formation process in the Ti-23Al-23Nb-1.4V-0.8Zr-0.4Mo-0.4Si (at.%) alloy based on orthorhombic titanium aluminide (Ti2AlNb), especially in the weld zone (WZ), heataffected zone (HAZ), and base metal (BM), during laser beam welding (LBW) at room temperature was considered. It was determined that the crack spread in the WZ throughout the crystallites of β-phas