Fabrication and properties of L-arginine-doped PCL electrospun composite scaffolds

The article describes fabrication and properties of composite fibrous scaffolds obtained by electrospinning of the solution of poly({\epsilon}-caprolactone) and arginine in common solvent. The influence of arginine content on structure, mechanical, surface and biological properties of the scaffolds was investigated. It was found that with an increase of arginine concentration diameter of the scaffold fibers was reduced, which was accompanied by an increase of scaffold strength and Young modulus. It was demonstrated that porosity and water contact angle of the scaffold are independent from arginine content. The best cell adhesion and viability was shown on scaffolds with arginine concentration from 0.5 to 1 % wt

Energetics of Propellant Options for High-Power Hall Thrusters

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76265/1/AIAA-16376-173.pd

Composite implants coated with biodegradable polymers prevent stimulating tumor progression

In this experiment we studied oncologic safety of model implants created using the solution blow spinning method with the use of the PURASORB PL-38 polylactic acid polymer and organic mineral filler which was obtained via laser ablation of a solid target made of dibasic calcium phosphate dihydrate. For this purpose the implant was introduced into the area of Wistar rats’ iliums, and on day 17 after the surgery the Walker sarcoma was transplanted into the area of the implant. We evaluated the implant’s influence on the primary tumor growth, hematogenous and lymphogenous metastasis of the Walker sarcoma. In comparison with sham operated animals the implant group demonstrated significant inhibition of hematogenous metastasis on day 34 after the surgery. The metastasis inhibition index (MII) equaled 94% and the metastases growth inhibition index (MGII) equaled 83%. The metastasis frequency of the Walker sarcoma in para aortic lymph nodes in the implant group was not statistically different from the control frequency; there was also no influence of the implant on the primary tumor growth noted. In case of the Walker sarcoma transplantation into the calf and the palmar pad of the ipsilateral limb to the one with the implant in the ilium, we could not note any attraction of tumor cells to the implant area, i.e. stimulation of the Walker sarcoma relapse by the implant. Thus, the research concluded that the studied implant meets the requirements of oncologic safety

Composite implants coated with biodegradable polymers prevent stimulating tumor progression

In this experiment we studied oncologic safety of model implants created using the solution blow spinning method with the use of the PURASORB PL-38 polylactic acid polymer and organic mineral filler which was obtained via laser ablation of a solid target made of dibasic calcium phosphate dihydrate. For this purpose the implant was introduced into the area of Wistar rats’ iliums, and on day 17 after the surgery the Walker sarcoma was transplanted into the area of the implant. We evaluated the implant’s influence on the primary tumor growth, hematogenous and lymphogenous metastasis of the Walker sarcoma. In comparison with sham operated animals the implant group demonstrated significant inhibition of hematogenous metastasis on day 34 after the surgery. The metastasis inhibition index (MII) equaled 94% and the metastases growth inhibition index (MGII) equaled 83%. The metastasis frequency of the Walker sarcoma in para aortic lymph nodes in the implant group was not statistically different from the control frequency; there was also no influence of the implant on the primary tumor growth noted. In case of the Walker sarcoma transplantation into the calf and the palmar pad of the ipsilateral limb to the one with the implant in the ilium, we could not note any attraction of tumor cells to the implant area, i.e. stimulation of the Walker sarcoma relapse by the implant. Thus, the research concluded that the studied implant meets the requirements of oncologic safety

Calcium phosphate coatings produced by radiofrequency magnetron sputtering method

Calcium phosphate coatings on titanium implants surface, produced by radio frequency (RF) magnetron sputtering method with hydroxyapatite solid target were investigated. It was found that produced coatings are calcium deficient compared to stoichiometric hydroxyapatite. The surface of the coatings is highly rough at the nanoscale and highly elastic. In vivo experiments on rats revealed that titanium implants with the calcium phosphate coatings do not cause negative tissue reaction after 6 months incubation period

The Fabrication of Bioresorbable Implants for Bone Defects Replacement Using Computer Tomogram and 3D Printing

The present work demonstrates the possibility of production of personalized implants from bioresorbable polymers designed for replacement of bone defects. The stages of creating a personalized implant are described, which include the obtaining of 3D model from a computer tomogram, development of the model with respect to shape of bone fitment bore using Autodesk Meshmixer software, and 3D printing process from bioresorbable polymers. The results of bioresorbable polymer scaffolds implantation in pre-clinical tests on laboratory animals are shown. The biological properties of new bioresorbable polymers based on poly(lactic acid) were studied during their subcutaneous, intramuscular, bone and intraosseous implantation in laboratory animals. In all cases, there was a lack of a fibrous capsule formation around the bioresorbable polymer over time. Also, during the performed study, conclusions were made on osteogenesis intensity depending on the initial state of bone tissue

The Fabrication of Bioresorbable Implants for Bone Defects Replacement Using Computer Tomogram and 3D Printing

The present work demonstrates the possibility of production of personalized implants from bioresorbable polymers designed for replacement of bone defects. The stages of creating a personalized implant are described, which include the obtaining of 3D model from a computer tomogram, development of the model with respect to shape of bone fitment bore using Autodesk Meshmixer software, and 3D printing process from bioresorbable polymers. The results of bioresorbable polymer scaffolds implantation in pre-clinical tests on laboratory animals are shown. The biological properties of new bioresorbable polymers based on poly(lactic acid) were studied during their subcutaneous, intramuscular, bone and intraosseous implantation in laboratory animals. In all cases, there was a lack of a fibrous capsule formation around the bioresorbable polymer over time. Also, during the performed study, conclusions were made on osteogenesis intensity depending on the initial state of bone tissue

Use of biodegradable polycaprolactone matrix for filling bone defects (experimental study)

Background. There are unresolved issues in bone defect management associated with complications, invasiveness and long duration of treatment. The use of elastic implants made of bioactive biodegradable materials that take any form of defect could close many of them.The aim. To investigate features of reparative regeneration in filling bone defects with an elastic degradable implant made of polycaprolactone (PCL) with and without hydroxyapatite (HA).Materials and methods. The study was carried out on 10 adult mongrel dogs. A non-through cylindrical hole, 4 mm in diameter and 10 mm deep, was modeled in the upper third of the diaphysis of the tibia. The defects thus formed were filled with an elastic degradable implant made of polycaprolactone. In Group 1, HA was not added to polycaprolactone, while HA was added in dogs of Group 2. Radiographic and histological methods were used to study the results.Results. It was found that the tested materials did not cause toxic and allergic reactions, both local and general, during intravital observations and in post-mortem anatomical preparations. After 28 days in both series, the implant biodegraded and was replaced by bone tissue. The proportion of the bone component and the numerical density of microvessels in the defect zone in Group 2 were significantly higher than in Group 1.Conclusion. Elastic implants produced of polycaprolactone by electrospinning are biologically compatible, biodegradable and can be used to heal bone defects. Hydroxyapatite that was added stimulates the activity of osteogenesis

INTERACTION OF BIORESORBABLE COMPOSITE IMPLANTS MADE BY SOLUTION BLOW SPINNING WITH TISSUES

This work represents the results of the study of the surrounding tissues reaction to the implantation of bioresorbable implants formed by the solution blow spinning from polylactic acid and ultrafine calcium phosphate powders, depending on the time and place of implantation. Using scanning electron microscopy it is shown that implants formed from randomly interwoven fibers have interconnected open porosity. It was established that the addition of calcium phosphate ultrafine powders does not cause changes in the formed implants structure. Histological investigation of tissue specimens from the implantation site revealed a high ability of created implants to successful integration with surrounding tissue after 15 days from the moment of implantation. Complete or partial implant resorption with substitution by own tissues was registered at 90 days after implantation. It was established that implantation of composite bioresorbable implants on the ilium bone stimulates the osteogenic process better than the implantation on skull bone within the same period. It was defined that scarification of the outer cortical plate in implant contact points with bone tissue increases the implants ability to stimulate osteogenic process. It was shown that the composite implants filled with calcium phosphate dibasic dehydrate in ultrafine powder form have the largest ability to stimulate osteogenesis

EFFECTIVE SEISMIC TECHNOLOGIES FOR NEW GEOLOGICAL DISCOVERIES IN EAST SIBERIA

Currently, East Siberia as a whole and the Republic of Sakha (Yakutia) in particular are the territories of extensive geological exploration. Field geophysical surveys are mainly performed by seismic technologies used to discover new deposits and provide data for detailed appraisal of the known fields. Three-dimensional seismic surveys are effectively used for clarifying the details of geologic structures and obtaining the data for drilling programs. Upon further development of technologies, improvements are introduced in field operations, seismic data processing and interpretation, and drilling programs. As the information content of the survey data increases, it becomes possible to revise and update geological models and/or develop them in a more detail. With the use of modern data processing technologies that preserve the signals and depth migration data, the tectonic model of the Srednebotuobinskoe Oil and Gas Condensate Field was fully modified. Furthermore, additional isolated tectonic blocks were discovered in the eastern part of the Central deposit, and their map was constructed. The geological exploration based on the updated tectonic model is successful – new mineral reserves have been discovered, and the vector of geological exploration has been completely changed