Poly-L-Lysine and Human Plasmatic Fibronectin Films as Proactive Coatings to Improve Implant Biointegration

The success of stable and long-term implant integration implies the promotion, control, and respect of the cell microenvironment at the site of implantation. The key is to enhance the implant–host tissue cross talk by developing interfacial strategies that guarantee an optimal and stable seal of soft tissue onto the implant, while preventing potential early and late infection. Indeed, implant rejection is often jeopardized by lack of stable tissue surrounding the biomaterial combined with infections which reduce the lifespan and increase the failure rate of implants and morbidity and account for high medical costs. Thin films formed by the layer-by-layer (LbL) assembly of oppositely charged polyelectrolytes are particularly versatile and attractive for applications involving cell–material contact. With the combination of the extracellular matrix protein fibronectin (Fn, purified from human plasma) and poly-L-lysine (PLL, exhibiting specific chain lengths), we proposed proactive and biomimetic coatings able to guarantee enhanced cell attachment and exhibiting antimicrobial properties. Fn, able to create a biomimetic interface that could enhance cell attachment and promote extracellular cell matrix remodeling, is incorporated as the anionic polymer during film construction by the LbL technic whereas PLL is used as the cationic polymer for its capacity to confer remarkable antibacterial properties.

When Students Faced Online Learning in Coronavirus Times: A Case Study

In this paper, we present survey research which we conducted at Maria Grzegorzewska University, Poland, on April 2nd-10th, 2020. This work aimed at gathering information about online learning responses among full-time students of pedagogy. Due to the pandemic situation caused by coronavirus all activities at Polish universities have been suspended. Nevertheless, the learning process has been continued. For the first three weeks, academics and students have tried to adjust to a completely new way of education design and work. Our research provides insight into students’ thoughts and emotions which accompanied them during those weeks of online learning courses. During the survey, respondents reported also their difficulties and observations regarding the quality of educational material, contact with lecturers, and reviewed assessments. In general, the majority of respondents have been doing well in this particular situation and positively evaluate the efforts of the lecturers. They find although online learning challenging. In the Introduction, we present circumstances of the research process and methodological background for the survey design. In the Methods section, we describe the survey structure and the respondent group, then we define the survey instruments. Next, the results are presented in two parts. First, we introduce the students’ experiences and emotions associated with online learning. Second, we show what respondents said about their actual online courses taken in the studied period. In the following discussion, we present the most important findings and their possible explanation. In Conclusion, we summarize our analysis of the collected material and make recommendations for future research.

Experimental study of fine-grained reticulated titanium nickelide in the near-defective tissues of the palate

Aim. To study the peculiarities of regeneration of fine-gauge reticulated titanium nickelide in near-defective tissues of the palate.Material and methods. The work was carried out on 10 female rabbits of the Shin Shila breed weighing 2,7-3,0 kg; an experimental investigation was carried out in the Central Research Laboratory of the Avicenna Tajik State Medical University. As the implantation material, we used a fine mesh titanium nickelide with a thickness of 40-50 microns threads and the size of 50x50 microns cells.Results and discussion. The morphological study revealed that after the surgery the mucous membrane covering the implant was edematous with foci of hyperemia and hemorrhages. Vessels were dilated and full-blooded, small and medium caliber vessels were constricted. In the zone of anastomosis, there were prevailing changes of inflammatory character with slight activation of local immunity. Fifteen days later the mucous membrane in the anastomosis zone partially recovered. Local immunity activation contributes to the restoration of normal structures in the implant area. Later it was noticed that as soon as blood supply to the implant zone was restored almost immediately from the areas bordering the operation zone the sprouting of the covering epithelium cells began.Conclusion. Regeneration processes in the artificially created defective areas of the palate, at the use of the titanium fine mesh nickelide begin on the border of the implant material contact with the tissues of the peri-defective zone at the expense of the local immune reactions activation with the following gradual transition to the other areas.

Process chain for the manufacture of hybrid bearing bushings

The current study presents a novel Tailored Forming process chain developed for the production of hybrid bearing bushings. In a first step, semi-finished products in the form of locally reinforced hollow profiles were produced using a new co-extrusion process. For this purpose, a modular tool concept was developed in which a steel tube made of a case-hardening steel, either C15 (AISI 1015) or 20MnCr5 (AISI 5120), is fed laterally into the tool. Inside the welding chamber, the steel tube is joined with the extruded aluminum alloy EN AW-6082. In the second step, sections from the compound profiles were formed into hybrid bearing bushings by die forging. In order to set the required forming temperatures for each material—aluminum and steel—simultaneously, a tailored heating strategy was developed, which enabled successful die forging of the hybrid workpiece to the desired bearing bushing geometry. Using either of the case-hardening steels in combination with aluminum, this novel process chain made it possible to produce intact hybrid bearing bushings, which showed both macroscopically and microscopically intimate material contact inside the compound zone.

ADAPTATION OF THE METHOD OF CONTROLLING CUTTING MODES TO INDUSTRIAL CONDITIONS

Variants of devices with the possibility of using the test pass method in industrial conditions for automatic determination of cutting modes by measuring the mutual properties of the tool - material contact pair through the value of the thermal EMF that occurs during machining are considered.

XVII Межгосударственная конференция Термоэлектрики и их применения --- 2021" (ISCTA 2021 Санкт-Петербург, 13-16 сентября, 2021 Получение и исследование омических контактов с высокой адгезией к термоэлементам

The factors determining the adhesive strength of film coatings are considered. The functions of contacts in thermoelements used in a wide temperature range were determined. It was established that the adhesive strength of contact is a limiting factor in the mechanical strength of a thermoelement. A method of vacuum sputtering of thin-film contacts was proposed, including the surface treatment of samples of thermoelectric materials. The presence of a transition layer in the area of the metal - thermoelectric material contact, formed during the interaction of the metal with elements of the thermoelectric material, was established. The dependence of the adhesive strength of film contact on roughness of surface on which they formed was established. Thermal stable contacts for thermoelements with low resistivity of the order of 10-9 Ohm•m2 and high adhesion strength of at least 12 MPa were obtained by ion-plasma sputtering.

Material Contact and Environmental Effects on Vitamin A Fortified Vegetable Frying Oil

Observations about the impact of environmental parameters and time, on fortified vegetable oil, using typical commercial grade linear low density polyethylene (LLDPE) packaging during typical shelf-life conditions, are minimal. We tested the long-term (12 months) impact of temperature and illuminance (light: 100 to 150 lux and darkness <1 lux) on refined bleached deodorized palm olein (RBDPOL), fortified with vitamin A, and without antioxidant. Results showed degradation of fortified RBDPOL with 70 ppm vitamin A was approximately 19% at 18-22oC in Light, 18% at 18-22oC in Darkness, 38% at 32-33oC in light and 24% 32-33oC in darkness. A similar trend was observed at 45 ppm vitamin A. Exposure to both heat and light impacted vitamin A degradation, but was primarily attributed to prolonged exposure at elevated temperature, irrespective of the packaging material. This short study validates extensive research by Silalahi et al., (2017), doi:10.1111/ijfs.13462 on the impact of environmental effects of fortified vegetable frying oil, during extensive storage life periods.

Effect of Sintering on In Vivo Biological Performance of Chemically Deproteinized Bovine Hydroxyapatite

The influence of the manufacturing process on physicochemical properties and biological performance of xenogenic biomaterials has been extensively studied, but its quantification on bone-to-material contact remains poorly investigated. The aim of this study was to investigate the effect of different heat treatments of an experimental chemically-deproteinized bovine hydroxyapatite in vivo in terms of new bone formation and osteoconductivity. Protein-free hydroxyapatite from bovine origin was produced under sub-critical conditions and then either sintered at 820 °C or 1200 °C. Structural and morphological properties were assessed by scanning electron microscopy (SEM), measurement of surface area and X-ray diffractometry (XRD). The materials were then implanted in standardized alveolar bone defects in minipigs and histomorphometric evaluations were performed using non-decalcified sections. Marked topographical differences were observed by SEM analysis. As the sintering temperature of the experimental material increased, the surface area significantly decreased while crystallite size increased. In vivo samples showed that the highly sintered BHA presented a significantly lower percentage of newly formed bone than the unheated one (p = 0.009). In addition, the percentage of bone-to-material contact (BMC) was significantly lowered in the highly sintered group when compared to the unsintered (p = 0.01) and 820 °C sintered (p = 0.02) groups. Non-sintered or sintered at 820 °C BHA seems to maintain a certain surface roughness allowing better bone regeneration and BMC. On the contrary, sintering of BHA at 1200 °C has an effect on its morphological and structural characteristics and significantly modify its biological performance (osteoconductivity) and crystallinity.