Lietuvoje kelio sąnario endoprotezavimo operacija yra viena dažniausiai atliekamų ortopedinių operacijų. Kasmet jų atliekama daugiau nei trys tūkstančiai. Tokiam aukštam endoprotezavimo operacijų ...skaičiui įtakos turi biologinis senėjimas bei lėtinių uždegiminių sąnarių ligų didėjimas. Kelio sąnario osteoartritu serga daugiau nei trečdalis žmonių vyresnių kaip 45 metų amžiaus. Kelio sąnario osteoartritas apriboja kelio sąnario judesių amplitudes ir turi įtakos funkcinei veiklai. Kelio judesių amplitudžių atgavimas yra vienas iš pagrindinių sėkmingo endoprotezavimo rodiklių. Norint atgauti funkciją, būtina pasiekti reikiamas judesio amplitudes. Kineziterapijos metu naudojamas nuolatinio pasyvaus judesio aparatas užtikrina ankstyvus judesius per kelio sąnarį. Tai viena iš daugelio kineziterapijos metu naudojamų priemonių ankstyvuoju pooperaciniu laikotarpiu po kelio sąnario endoprotezavimo operacijos. Teoriniu požiūriu, nuolatinio pasyvaus judesio aparato naudojimas po kelio sąnario endoprotezavimo operacijų gerina amplitudes kelio sąnaryje, padeda sumažinti pooperacinį tinimą, skausmą, gerina kraujotaką bei padeda išvengti sąaugų susidarymo. Naujausios tyrimo išvados rodo, kad po kelio sąnario endoprotezavimo operacijos nuolatinio pasyvaus judesio aparato taikymas dvi valandas per dieną kartu su pratimais žymiai padidina blauzdos lenkimo amplitudę, nesukeliant skausmo. Šio tyrimo tikslas – atskleisti nuolatinio pasyvaus judesio aparato taikymą pacientams po kelio sąnario endoprotezavimo operacijos, kojos funkcijai atgauti. Tyrimo metu atlikti skausmo intensyvumo, tinimo judesių amplitudės, raumenų jėgos ir funkcinio pajėgumo vertinimai. Įvertinus nuolatinio pasyvaus judesio aparato taikymą pacientams po kelio sąnario endoprotezavimo operacijos, skausmo intensyvumas, tinimas po kineziterapijos sumažėjo, blauzdos judesių amplitudė, raumenų jėga, funkcinis pajėgumas padidėjo statistiškai reikšmingai (p<0,05).
Display omitted
•MXenes significantly increase the elastic properties of the composite.•The aligned placement leads to much higher stiffness along the alignment direction.•Higher inclusion aspect ...ratios contribute to a higher increase in stiffness.•MXenes show promise as fillers for novel high-strength multifunctional composites.
This paper presents a numerical investigation of the elastic properties of a novel hybrid polymer composite reinforced with graphene and MXene nanosheets. A finite element computational model was developed to analyze the mechanical properties of a new polymer hybrid composite reinforced with MXene and graphene taking into account the properties of the 2D nanosheets, different aspect ratios, placement options and volume fractions of nanoreinforcements, as well as the interaction effects between the nanofillers and the surrounding polymer matrix. Using the developed numerical model, the influences of the interface layer properties, MXene and graphene aspect ratio, alignment and volume fraction on the orthotropic mechanical properties of the proposed novel hybrid polymer nanocomposites were determined. The results suggest that MXenes along with graphene nanosheets show considerable promise in the development of novel nanoengineered high-strength multifunctional composite materials, as well as provides insight for future design of such materials.
Inthis study, the carbon fibre reinforced methyl methacrylate (CF/MMA) compositetoecap for safety shoes was manufactured to increase the energy absorptioncapacity during impact. Different types of ...nanofillers such as organic andinorganic nanotubes, unmodified and organically modified nanoclays were appliedto modify matrix impact properties. The drop-weight impact tests of thenanocomposite toecap were performed with respect to nanofiller nature andcarbon fibre stacking sequence. It was found that the most influence on thestiffness and impact damage of the carbon fibre methyl methacrylatenanocomposite toecaps besides stacking sequence show organic and inorganic nanotubesor unmodified nanoclay.DOI: http://dx.doi.org/10.5755/j01.ms.21.2.7075
In this study, the liquid phase and vapor phase procedures for silylating cellulose microfibers by hexamethyldisilazane (HMDS) were compared in terms of efficiency. The influence of functionalization ...degree on the morphology of microfibers and their interaction with polydimethylsiloxane (PDMS) matrix has been investigated. The antibacterial properties of silylated cellulose microfibers hybridized with Ag nanoparticles, obtained by in situ chemical reduction, were also studied. Sample morphology investigations were carried out using spectroscopy and microscopy techniques (FTIR, XPS, TEM, SEM, EDS, XPS). Trimethylsilyl moieties appear on the surface of the cellulose microfibers after modification and improve the dispersibility of the microfibers, allowing strong interaction with the PDMS matrix and favoring its crosslinking density. Microfibers functionalized by the vapor phase of HMDS show smoother surfaces with higher concentrations of Si-containing groups, resulting in a more hydrophobic wetting behavior and a greater influence on the mechanical properties of the polymer. The silylated cellulose microfiber–Ag nanohybrid shows stronger antimicrobial activity towards Gram-positive and Gram-negative bacteria strains compared to that of the untreated hybrid. A PDMS composite loaded with this hybrid exhibits the ability to inhibit bacterial growth.
The most effective means to protect against bacterial invasion and to reduce the risk of healthcare-associated infections are antibacterial components synthesis. In this study, a novel process for ...the synthesis of organic-inorganic hybrid coatings containing silver nanoparticles is presented. Silver nanoparticles and polymer formation proceeds simultaneously through the in situ photoreduction of silver salt to silver nanoparticles and UV-crosslinking of bifunctional aliphatic silicone acrylate. The nanocomposite films with 0.5-1.43 wt % of silver nanoparticles concentration were obtained and investigated. The formation of silver nanoparticles in polymer matrix was confirmed via UV-visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy, scanning electron spectroscopy, and energy dispersive spectroscopy. Our investigations clearly show the formation of silver nanoparticles in silicone acrylate network. Direct photoreduction of silver salt by UV-radiation in the organic media produced silver nanoparticles exhibiting cubic crystal structure. The size of nanoparticles was determined to be near 20 ± 5 nm. The antibacterial activities of coatings were determined using the disc diffusion and direct contact methods. UV-curable silicone acrylate hybrid coatings exhibited antibacterial activity against harmful bacteria strains.
•New surface roughness modelling method is created.•Proposed method is based on the modelling of surface profile points by parts of the parabola.•New method is suitable for three-dimensional polymer ...blends surface roughness description.•The comparison of proposed method efficiency with other known modelling methods was made.
In this study the effect of polymer blend composition on the surface roughness has been investigated and simulated. Three-dimensional modeling of chloroprene rubber film surface upon piperylene-styrene copolymer content was conducted. The efficiency of various surface roughness modeling methods, including Monte Carlo, surface growth and proposed method, named as parabolas, were compared. The required parameters for modeling were obtained from atomic force microscopy topographical images of polymer films surface. It was shown that experimental and modeled surfaces have the same correlation function. The quantitative comparison of function parameters was made. It was determined that novel parabolas method is suitable for three-dimensional polymer blends surface roughness description.
The influence of plasma treated bentonite on the properties and structure of mechanically recycled polycaprolactone‐based thermoplastic polyurethane/polycaprolactone blend (rTPU‐PCL) was ...investigated. The bentonite clay was modified with oxygen, argon, and air plasma. The obtained rTPU‐PCL/clay nanocomposites were characterized by Fourier infrared spectroscopy, X‐ray diffraction, atomic force microscopy, and scanning electron microscopy analyses. X‐ray diffraction showed the increase of spacing between diffraction lattice planes of plasma treated bentonite. The treatment by plasma improves the clay dispersion in rTPU‐PCL matrix independently on used plasma gasses. The mechanical properties of nanocomposites were improved when plasma treated clay was used.
Oxygen, argon, or air plasma was used for the surface treatment of the bentonite clay as an alternative to the classical chemical organo treatment. The modification of the bentonite improves its affinity with mechanically recycled polycaprolactone‐based thermoplastic polyurethane/polycaprolactone blend (rTPU‐PCL). The mechanical properties of rTPU‐PCL and bentonite nanocomposites depend on used plasma gasses.
Lietuvoje niekada nesportuoja ir nesimankština 46 proc. žmonių, ir pagal šį rezultatą esame 9-oje vietoje tarp fiziškai neaktyviausių Europos Sąjungos šalių. Panaši tendencija stebima ir tarp ...studentų, pastebėta, kad jie dažniau renkasi fiziškai lengvą, mažo intensyvumo veiklą laisvalaikiu ir tik kas trečias užsiima aukšto ar vidutinio intensyvumo veikla. Fizinis aktyvumas – vienas iš pagrindinių būdų, norint išsaugoti ir sustiprinti sveikatą. Ypač fizinis aktyvumas aktualus šiuo metu, visame pasaulyje siaučiant COVID-19 pandemijai. Šalyje uždarius sporto klubų veiklą, apribojus gyventojų fizinį judėjimą, tarp jų ir studentų, žymiai sumažėjo jų fizinis aktyvumas. Didžiąją laiko dalį studentams tenka praleisti namuose. Išlikti fiziškai aktyviems yra rimtas iššūkis. Laikas, praleidžiamas sėdint ir žemas fizinio aktyvumo lygis, gali turėti neigiamos įtakos sveikatai ir gyvenimo kokybei. Karantino metu įvesti apribojimai gali turėti neigiamų pasekmių psichinei bei fizinei sveikatai, sukelti stresą. Todėl fizinis aktyvumas kaip sveikos gyvensenos veiksnys šiuo laikotarpiu yra ypač aktualus ir reikšmingas. Šio tyrimo tikslas – įvertinti studentų fizinį aktyvumą ir emocinę būseną karantino laikotarpiu. Į tyrimą įsitraukė 502 Vilniaus kolegijos studentai. Tyrimo metu naudotas anketavimas, duomenų analizė su Windows Excel duomenų analizės programa. Įvertinus Vilniaus kolegijos studentų fizinį aktyvumą iki karantino paskelbimo ir karantino laikotarpiu nustatytas studentų fizinio aktyvumo mažėjimas, kurį lėmė fizinio intensyvumo sumažėjimas. Įvertinus Vilniaus kolegijos studentų praktikuojamas fizines veiklas iki karantino ir karantino laikotarpiu nustatytas didesnio fizinio intensyvumo reikalaujančių veiklų sumažėjimas ir laiko, skiriamo šioms veikloms, sutrumpėjimas.
PDF
