Priporočila za obravnavo bolnikov z bazalnoceličnim karcinomom

no abstractni abstrakt

Precise dosing of powder materials with a collaborative robot

Naloga obsega razvoj robotskega sistema za mikrodoziranje. To je precizno doziranje praškastih materialov v določen nosilec. Sistem sestoji iz nalaganja materiala na dozirno spatulo in doziranja v dozirno posodo. Tehniki nalaganja in doziranja sta izvedeni po zgledu človeka. Demonstracijo nalagalnega giba smo posneli s kinestetičnim vodenjem robota. Gib je parametriziran z uporabo dinamičnih primitivov gibanja (DMP), kar nam dovoljuje prilagajanje nalagalnega mesta v odjemni posodi. To je določeno s pregledom površine praška z laserskim senzorjem. Demonstracije dozirnega giba smo posneli z optičnim sistemom za zajem gibanja. Gib smo prilagodili izvedbi z robotom in ga parametrizirali s periodičnimi dinamičnimi primitivi gibanja (pDMP). Doziranje poteka kot regulacija frekvence dozirnega giba na podlagi modela praška ter merjene mase v dozirni posodi in na spatuli. Preizkusili smo tudi regulacijo s PID regulatorjem, vendar se je izkazala za nezanesljivo. Sistem smo testirali z mikrokristalno celulozo (MCC), na območju [0,~30]~mg. Razširjena negotovost rezultatov je podobna negotovosti meritev: 2,6~mg. Največja prispevka k slednji sta variabilnost vzorcev in motnje iz okolja, predvsem spremembe zračnega tlaka. Ker negotovost meritev vpliva na kvaliteto modela sklepamo, da bi v primernejšem okolju lahko dosegli še boljše rezultate. Robot je bolj natančen, kakor človek z enako tehniko. Z natančnostjo izurjenih strokovnih delavcev je primerljiv, odvisno od izkušenj. Za namensko grajenimi stroji zaostaja približno za faktor 10.This work encomapsses the development of a robotic microdosing system. Microdosing is the science of precise delivery of powders into a chosen vessel. The system consists of two parts: loading material onto the dosing spatula and microdosing said material into the dosing dish. Both actions are exectued by following human demonstration. The demonstration of the loading motion was recorded by kinesthetic guidance of the robot arm. The motion was parametrized with dynamic movement primitives (DMPs), allowing us to dynamically adjust the loading point in the loading area. The loading point\u27s location is determined by scanning the powder surface with a laser scanner. The demonstrations of the dosing motion were captured using an optic motion tracking system. We adjusted the motion to be suitable for execution with the robot and parametrized it using periodic dynamic movement primitives (pDMPs). Microdosing is realised as regulation of the dosing motion\u27s frequency, based on a model of the powder in conjuction with the measured mass in the dosing dish and on the spatula. We also considered and tested PID regulation, which proved unreliable. We performed an evaluation of the system in the range [0,~30]~mg, using microcrystal cellulose (MCC) powder. The expanded uncertianty of the results is similar to that of measurements: 2.6~mg. The most significant contributors to the latter are the variablity of samples and environmental noise, predominantly changes in air pressure. Because the quality of measurements directly affects the quality of our model, we presume considerably better results could be obtained in a more suitable environment. The robot achieves greater precision than a human using the same technique. It\u27s precision is comparable to that of trained experts, with some variance due to differing levels of experience. It\u27s unable to meet the precision of purpose built machinery, falling short by about a factor of 10

A mathematical model for pH-responsive ionically crosslinked TEMPO nanocellulose hydrogel design in drug delivery systems

Ionically crosslinked hydrogels based on TEMPO nanocelullose and alginate were prepared to develop a generalized pH value, temperature and biopolymer concentration dependent mathematical model. The distinctive attention was in the demonstration of hydrogen bonds effects in the mathematical model, prevailing especially in the field of low crosslink densities of TEMPO nanocellulose hydrogel in acid medium. Accordingly, alginate hydrogelswere subjected to the research as comparable samples with less significant hydrogel bonds effect. The equation was built upon the determination of the average mesh size in a TEMPO nanocellulose and alginate hydrogel network and studying its changes in different pH release environments. Based on rheological measurements of TEMPO nanocellulose and alginate from the basic and acidic release environment, the mechanism of swelling and shrinkage was thoroughly discussed as well as the influence of substituent groups, ionic interactions and hydrogen bonds in different pH medium were evaluated. Due to the protonation of carboxylic groups, TEMPO nanocellulose and alginate hydrogels shrink in an acid environment. The presented approach will accelerate, improve and reduce the cost of research in the field of controlled release technology with target drug delivery

Kinetic model of a Diels-Alder reaction in a molten state

Information on the reaction kinetics in the melt is a valuable prerequisite for a successful application of self-healing ability to benzoxazine-based thermosetting resins. The goal of this research was to develop a kinetic model of the Diels–Alder (DA) reaction in a molten state between N-phenylmaleimide (PMI) and benzoxazine-containing furan group (G-f). Rheological data were found to be of significant importance in the kinetic model development and interpretation. The increase in viscosity, the occurrence of side reactions, and equilibrium between DA and r-DA reaction were identified as possible reasons for the deceleration of reaction rate and limiting conversion. After a thorough investigation of the studied system, accompanied by the knowledge from the literature, the potential reason for the incomplete conversion of reactants was reduced to the crossover between chemically and diffusion-controlled reaction due to the increasing viscosity of reaction system. Accordingly, the kinetic model based on the combination of Rabinowitch equation and Chern–Poehlein model was used to accurately describe the progress of the studied reaction in the molten state

The use of ultrasound in the crystallization process of an active pharmaceutical ingredient

In this research, ultrasound was used in the crystallization process as an alternative to conventional spontaneous crystallization and seeding crystallization. The study was implemented on an active pharmaceutical ingredient ticagrelor, where the influence of ultrasound on its physical properties was evaluated. Process parameters of spontaneous crystallization, seeding crystallization and ultrasound-assisted crystallization were extensively studied while the pros and cons of each were adequately exposed. Compared to spontaneous crystallization and seeding crystallization ultrasound-assisted crystallization has significantly improved fundamental crystallization parameters: nucleation, the growth of crystals and filtration time. At the same time, the tendency of particles to agglomerate was reduced, which lead to the avoidance of energy and time-consuming process of final product deagglomeration, often problematic in conventional crystallization. In addition, different physical properties of ticagrelor were reached and evaluated, for instance, morphology, particle size distribution and different polymorphic forms. Polymorphic forms I, II and III were efficiently produced in a repeatable, robust and optimal way. Ultrasound-assisted crystallization was proved to have a beneficial effect on the crystallization process of API, even on the industrial scale, and can successfully replace spontaneous crystallization and seeding crystallization

A rheological study of cationic micro- and nanofibrillated cellulose

Driven by the demand for various cationic biopolymers in recent years, the quaternization of cellulose nanofibers was carefully investigated to have tight control over their final characteristics. The addition of sodium hydroxide (NaOH) to the reaction mixture is crucial as it catalyzes the conversion of alcohol groups of cellulose into more reactive alcoholate groups. On the other hand, excessive concentration proves to inhibit the reactivity of hydroxyl groups. The addition of glycidyltrimethylammonium chloride (GTMAC) increases the yield of the trimethylammonium chloride content (TMAC) reaction, while in excess it affects the rheological properties of the quaternizated cellulose nanofibers. The effects of NaOH and GTMAC on the TMAC content and rheological properties have been investigated in detail and mathematically evaluated. Furthermore, a comparison of the viscoelastic behavior and shear thinning character of commercial cationic micro- and nanofibrillated cellulose is presented. The research allows to extend the possibility of using cellulose in many applications of cationic biopolymers

The mutual effect of the crosslinker and biopolymer concentration on the desired hydrogel properties

Controlled release technology has a great potential in pharmaceutical and medical applications to ensure high efficacy of treatment, reduces the aggressive action of the medicines per patient, decreases the cost of treatment and reduces the side effects of the drug as well. In this research, hydrogels from biopolymers were designed for potential use in the drug release systems. The main objective was the manipulation of alginate and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) - oxidized cellulose nanofibers hydrogels crosslinking density by changing the biopolymer and crosslinker concentrations. Rheological measurements of prepared hydrogels were performed to determine the viscosity as a biomedical applicability factor and for determining shear modulus as a basis for theoretical mesh size calculations. The homogeneity of the hydrogel was confirmed by NMR verifying the validity of the mesh size calculations at the same time. In the last stage, the improved mathematical model was developed taking into account the concentration of crosslinker and the concentration of biopolymer in hydrogel as well. The designed model is the first step for the preparation of hydrogels with specific properties

A green approach toward epoxy-benzoxazine copolymers with shape-memory ability

In the frame of green-based chemistry, advanced shape memory polymers are designed from benzoxazine (RSBOX) and epoxy (R-EP) resins basing on potential natural raw materials, such as resorcinol and stearylamine. Thermal curing, investigated by differential scanning calorimetry, shows several overlapping peaks suggesting a complex curing mechanism. Dynamic mechanical analysis of cured RS-BOX/R-EP copolymers demonstrates an increase in the glass temperature and narrower glass transition by the increase of the RS-BOX ratio. In contrast, crosslinking density increases with higher epoxy resin content. All investigated materials possess one-way dual shape memory ability triggered by glass transition temperature with excellent shape fixity, while the shape recovery values ranged between 95 and 100%. The duration of the recovery process is significantly influenced by the RS-BOX amount. Additionally, the mechanical and shape memory properties of fully bio-based SMPs might be suitably tailored for advanced applications by merely varying the initial composition

Effect of polymer-polymer interactions on the flow behavior of some polysaccharide-based hydrogel blends

This study is the continuation of our previous work (Kopač, Abrami, et al., 2021) where the theoretical approach of polymer-polymer interaction to predict the crosslink density of hydrogels was introduced. This theory is further extended to the flow properties of hydrogels that allow the analysis of synergistic effect in hydrogel systems and the understanding of possible anomalous behavior of certain mixtures. Various hydrogel structures were prepared accordingly by blending scleroglucan, anionic nanocellulose, Laponite dispersions and alginate solution. The relationship between mechanical and flow properties of the hydrogel network was carefully studied and eventually described by mathematical model. The linear model equation to predict yield stress of hydrogels in relation to the crosslink density was designed showing a satisfactory agreement between experimental data and model predictions. The correlation was adjusted by defining a proportionality coefficient, representing the energy defined per moles of crosslinks that can be used to restore the deformation