Dielectric, thermal and mechanical properties of l,d-poly(lactic acid) modified by 40-pentyl-4-biphenylcarbonitrile and sngle walled carbon nanotube

We report here the preparation and thermal, electrical and mechanical characterization of binary and ternary films based on l,d-poly(lactic acid) (l,d-PLA) and 4′-pentyl-4-biphenylcarbonitrile (5CB) and Single Walled Carbon Nanotubes (SWCN) with various weight ratio. The transitions for all investigated hybrid compositions detected by differential scanning calorimetry method were shifted to lower temperatures with increasing the concentration of 5CB in the mixture with polymer. Frequency domain dielectric spectroscopy method and thermal imaging together with polarized optical microscope were used to study electric and structural properties of created hybrid compositions. The best electrical conductivity was observed for hybrid composite l,d-PLA:5CB:SWCN with ratio 10:1:0.5 w/w/w - resistance of 41.0 Ω and thermal response up to 160 °C without causing any damages. Films in crystal form are much more inflexible than in amorphous and can be explain by the cold crystallization occurs at heating while the materials changed their physical state. The value of ε′ increases with increasing the 5CB admixture. Moreover, the addition of 5CB to l,d-PLA resulted in increased flexibility of polymeric base films. The best material flexibility and short-term strength were obtained for l,d-PLA sample with 9% 5CB content

Hybrid materials based on L,D-poly(lactic acid) and Single-Walled Carbon Nanotubes as flexible substrate for organic devices

We report on the application of l,d-poly(lactic acid) (l,d-PLA) with dispersed Single-Walled Carbon Nanotubes (SWCN) as a flexible translucent electrode for organic devices. We used commercially available nanotubes in various weight ratios from 0 to 8% dispersed in chloroform polymeric solution by ultrasonication and were drop cast. The created hybrid materials were investigated by differential scanning calorimetry to determine the influence of SWCN content on the thermal behavior, while polarizing optical microscope was used to find the effect of mechanical deformations on the textures. Drop-cast films were studied by optical transmittance, conductivity, dielectric properties and by thermal imaging under applied potential. Thermal imaging provided evidence of visible voltage-activated conduction. Simple mechanical deformation such as bending with stretching at edge to ca. 90 and elongation test were performed. Moreover, interactions between l,d-poly(lactic acid) and SWCN were investigated by FT-IR and NMR spectroscopy. Finally, we can conclude that the thermographic examination of created films permits fast, simple and inexpensive localization of defects on the surface of l,d-PLA:SWCN film, together with the electrical properties of the films

Przeszczepienie nerki u bezobjawowej pacjentki wysokiego ryzyka sercowo-naczyniowego — opis przypadku oraz przegląd literatury

Cardiovascular complications are the most frequent cause of death of patients with Chronic Kidney Disease (CKD) at each stage of this disease. Cardiovascular risk decreases after kidney transplantation, but it still remains high, with 5% of deaths due to acute coronary syndrome occurring in the first year following kidney transplantation. In the case of CKD patients, cardiovas­cular complications secondary to rapidly progressing atherosclerosis result from both conventional and un­conventional ischaemic heart disease (IHD) risk fac­tors, the latter being conditioned by a specific metabolic nature of this disease. Following kidney transplantation, this risk is increased both by the surgical procedure it­self and an atherogenic activity of immunosuppressive drugs. A well-documented angiospastic effect of calci­neurin inhibitors is also of importance here. This study discusses a case of a 58-year-old female patient receiving hemodialysis, with G5 stage CKD secondary to diabetic kidney disease, with a history of type 2 diabetes of many years, and many cardiovas­cular complications. The long qualification process for kidney transplantation is analyzed, focusing on its different stages, as well as difficulties during the transplantation procedure and complications after kidney transplantation, resulting in the loss of the graft during one-year follow-up period. Additionally, reports from available studies that suggest a selec­tion of immunosuppressive drugs in high cardio­vascular risk patients are discussed. Complications experienced by the patient following the transplan­tation — myocardial infarction with a sudden car­diac arrest, life-threatening cardiogenic shock, acute transplant rejection, and finally the loss of the graft, serve the authors to discuss benefits and losses in the kidney transplantation qualification process in the case of patients with such complex risk factors.Powikłania sercowo-naczyniowe to najczęstsza przyczyna zgonów pacjentów z przewlekłą chorobą nerek (PChN) na każdym etapie tej choroby. Ryzyko sercowo-naczyniowe po przeszczepieniu nerki ma­leje, ale nadal pozostaje na wysokim poziomie; 5% zgonów z powodu ostrego zespołu wieńcowego wy­stępuje w pierwszym roku po przeszczepieniu nerki. W przypadku pacjentów z PChN do powikłań serco­wo-naczyniowych na tle szybko postępującej miaż­dżycy tętnic doprowadzają zarówno konwencjonalne, jak i niekonwencjonalne czynniki ryzyka choroby nie­dokrwiennej serca (ChNS); te ostatnie są uwarunko­wane szczególnym tłem metabolicznym choroby. Po przeszczepieniu nerki ryzyko to zwiększają sam za­bieg operacyjny oraz aterogenne oddziaływanie leków immunosupresyjnych. Rolę odgrywa tu również do­brze udokumentowane naczynioskurczowe działanie inhibitorów kalcyneuryny. W pracy opisano przypadek 58-letniej hemodializo­wanej pacjentki z PChN w stadium G5 w przebiegu cukrzycowej choroby nerek, z wieloletnią cukrzycą typu 2, z licznymi powikłaniami sercowo-naczy­niowymi. Przeanalizowano etapami długotrwały proces kwalifikacji do przeszczepienia nerki, trud­ności podczas zabiegu transplantacji, powikłania po przeszczepieniu nerki, zakończone w rocznej obserwacji utratą nerki przeszczepionej. Przyto­czono również dane z piśmiennictwa, sugerujące dobór protokołu immunosupresyjnego u pacjen­tów wysokiego ryzyka sercowo-naczyniowego. Skomplikowane losy pacjentki po transplantacji — przebyty zawał z nagłym zatrzymaniem krąże­nia, wstrząs kardiogenny z bezpośrednim zagroże­niem życia, ostre odrzucanie nerki przeszczepionej, a wreszcie jej utrata — posłużyły autorom pracy do otwartej dyskusji nad bilansem zysków i strat w procesie kwalifikacji do przeszczepienia nerki tak obciążonych biorców

A Flow Analysis Using a Water Tunnel of an Innovative Unmanned Aerial Vehicle

The purpose of this article is to present and discuss the results of a non-standard unnamed aerial vehicle construction with a constant cross-section square-shaped avionic profile. Based on the model’s in-air observed maneuverability, the research of avionic construction behavior was carried out in a water tunnel. The results show the model’s specific lift capabilities in comparison to classical avionic constructions. The characteristic results of the lift coefficient showed that the unmanned aerial vehicle presents favorable features than classic avionic constructions. The model was created with the prospect of using it in the future for dual-use purposes, where unmanned aerial vehicles are currently experiencing very rapid development. When creating the prototype, the focus was on low production cost, as well as convenience in operation. The development of this type of breakthrough avionic solution, which shows extraordinary maneuverability, may contribute to increasing the popularity and, above all, the availability of unmanned aerial vehicles for the largest possible group of recipients because of high avionic properties in relation to the technical construction complexity

Comparative Analysis of Fluorine-Containing Mesogenic Derivatives of Carborane, Bicyclo[2.2.2]octane, Cyclohexane, and Benzene using the Maier–Meier Theory

Two series of related three-ring nematoges with Δε > 0 and containing 12-vetex carborane (<b>A</b>), 10-vertex carborane (<b>B</b>), bicyclo[2.2.2]­octane (<b>C</b>), cyclohexane (<b>D</b>) and benzene (<b>E</b>) were prepared and investigated as additives to 6-CHBT nematic host and in the pure form (series <b>2</b>). Dielectric results were analyzed with the Maier–Meier relationship to gain an understanding of behavior of additives in nematic solutions. Molecular parameters for each nematogen were obtained at the B3LYP/6-31G­(d,p) level of theory in the host’s dielectric medium, and dielectric data was used as the only experimental parameter to calculate apparent order parameter <i>S</i>_app and the Kirkwood factor <i>g</i>. The results demonstrated that compounds in series <b>1</b> stabilize the nematic phase (high <i>S</i>_app) of the host more than additives in series <b>2</b> (low <i>S</i>_app), and carbocycles <b>C</b> and <b>D</b> are more effective (higher <i>S</i>_app) than carborane analogues <b>A</b> and <b>B</b> (lower <i>S</i>_app). The method provides insight into behavior of additives in nematic solutions and is useful for comparative analysis of a series of compounds or a series of hosts

On the Feasibility of an LCD-Based Real-Time Converter for Ionizing Radiation Imaging

Here we present the cascade converter (CC), which provides real-time imaging of ionizing radiation (IoR) distribution. It was designed and manufactured with the simplest architecture, utilizing liquid crystal display (LCD) technology. Based on two merged substrates with transparent electrodes, armed with functional layers, with the cell filled with nematic liquid crystal, a display-like, IoR-stimulated CC was achieved. The CC comprises low-absorbing polymer substrates (made of polyethylene terephthalate—PET) armed with a transparent ITO electrode covered with a thin semipermeable membrane of polymer (biphenylperfluorocyclobutyl: BP-PFCB) doped with functional nanoparticles (NPs) of Lu2O3:Eu. This stack was covered with a photoconductive layer of α-Se and finally with a thin polyimide (PI) layer for liquid crystal alignment. The opposite substrate was made of LCD-type glass with ITO and polyimide aligning layers. Both substrates form a cell with a twisted structure of nematic liquid crystal (TN) driven with an effective electric field Eeff. An effective electric field driving TN structure is generated with a sum of (1) a bias voltage VBIAS applied to ITO transparent electrodes and (2) the photogenerated additional voltage VXray induced between ITO and α-Se layers with a NPs-doped BP-PFCB polymer layer in-between. The IoR (here, X-ray) conversion into real imaging of the IoR distribution was achieved in the following stages: (1) conversion of IoR distribution into non-ionizing red light emitted with functional NPs, (2) transformation of red light into an electric charge distributed in a layer of the photoconductive α-Se, which is what results in the generation of distributed voltage VXray, and (3) a voltage-mediated, distributed switching of the TN structure observed with the naked eye. The presented imaging device is characterized by a simple structure and a simple manufacturing process, with the potential for use as a portable element of IoR detection and as a dosimeter

CVD-Graphene-Based Flexible, Thermoelectrochromic Sensor

The main idea behind this work was demonstrated in a form of a new thermoelectrochromic sensor on a flexible substrate using graphene as an electrically reconfigurable thermal medium (TEChrom™). Our approach relies on electromodulation of thermal properties of graphene on poly(ethylene terephthalate) (PET) via mechanical destruction of a graphene layer. Graphene applied in this work was obtained by chemical vapor deposition (CVD) technique on copper substrate and characterized by Raman and scanning tunneling spectroscopy. Electrical parameters of graphene were evaluated by the van der Pauw method on the transferred graphene layers onto SiO2 substrates by electrochemical delamination method. Two configurations of architecture of sensors, without and with the thermochromic layer, were investigated, taking into account the increase of voltage from 0 to 50 V and were observed by thermographic camera to define heat energy. Current-voltage characteristics obtained for the sensor with damaged graphene layer are linear, and the resistivity is independent from the current applied. The device investigated under 1000 W/m2 exhibited rise of resistivity along with increased temperature. Flexible thermoelectrochromic device with graphene presented here can be widely used as a sensor for both the military and civil monitoring

Influence of TiO₂ Nanoparticles on Liquid Crystalline, Structural and Electrochemical Properties of (8Z)-N-(4-((Z)-(4-pentylphenylimino)methyl)benzylidene)-4-pentylbenzenamine

Organic&#8211;inorganic hybrids based on liquid crystalline symmetrical imine (8Z)-N-(4-((Z)-(4-pentylphenylimino)methyl)benzylidene)-4-pentylbenzenamine (AZJ1) with two aliphatic chains and TiO2 nanomaterials were obtained and investigated taking into account thr crystallographic form of titanium dioxide i.e., anatase versus rutile. The type of TiO2 influences the mesomorphic properties of imine AZJ1, as observed by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) techniques. Fourier-Transform Infrared Spectroscopy (FT-IR) was used to investigate the interactions of oxygen vacancies located on the TiO2 surface with the studied AZJ1 imine together with studying the influence of temperature. Both imine:TiO2 anatase versus rutile hybrids possessed the highest occupied molecular orbital (HOMO) levels of about &#8722;5.39 eV (AZJ1:anatase) and &#8722;5.33 eV (AZJ1:rutile) and the lowest unoccupied molecular orbital (LUMO) levels of about &#8722;2.24 eV. The presence of TiO2 in each hybrid did not strongly affect the redox properties of imine AZJ1. Organic devices with the configuration of ITO/TiO2/AZJ1 (or AZJ1:TiO2 anatase versus rutile)/Au were fabricated and investigated in the presence and absence of visible light irradiation with a light intensity of 93 mW/cm2. Finally, to analyze defects in the constructed organic devices we used thermal imaging and atomic force microscopy (AFM). The addition of TiO2 in both crystallographic forms has a positive influence on layer-forming properties that manifests itself as a very homogenous heat distribution for the whole sample