Andres Krumme

Low cost anatomically realistic renal biopsy phantoms for interventional radiology trainees

This paper describes manufacturing of economically affordable renal biopsy phantoms for radiology residents and practicing radiologists. We reconstructed a realistic 3-dimensional patient-specific kidney model from CT data, manufactured an organ mould and casted the kidney phantoms. Using gelatin gel materials with calibrated parameters allowed making phantoms with realistic mechanical, ultrasound and CT properties including various pathologies. The organ phantoms with cysts included were further casted into gelatin gel medium. They were validated by radiology residents in biopsy training and compared against self-made phantoms traditionally used in the curriculum of interventional radiology. The realism, durability, price and suitability for training were evaluated. The results showed that our phantoms are more realistic and easier to use than the traditional ones. Our proposed technology allows creating a low-cost (50

Measuring crystallization kinetics of high density polyethylene by improved hot-stage polarized light microscopy

/kg) alternative to the pricy commercial training phantoms available today.

Influence of Preparation Process on Morphology and Conductivity of Carbon Black-Based Electrospun Nanofibers

Abstract This article describes a device developed for measuring crystallization kinetics of fast crystallizing polymers, for example, high density polyethylene. It consists of a commercial polarized light microscope with image acquisition system, a unique hot stage with temperature control system and software for temperature control and image analysis. The device enables controlled cooling rate of 1000°C/min and on-line image analysis capacity of five pictures per second. Suitability of the device’s cooling rate for the analysis of polyethylene crystallization is explained. The image analysis process is described. Two different algorithms for object counting are compared and their object recognition capacities are explained. Some results obtained with this device concerning a high density polyethylene sample are presented.

Permeability of water and oleic acid in composite films of phase separated polypropylene and cellulose stearate blends.

In this work, three different methods of preparation of polyacrylonitrille (PAN) with carbon black (CB) solutions further used in electrospinning for producing conductive fiber mats are discussed. CB is used as conductive filler. Content of CB in polymer matrix is varied, CB/PAN = 1/2, 1/1, and 3/2. The solution properties and obtained fiber morphology are analyzed. The effect of preparation on fiber morphology and conductivity is analyzed, as well as the effect of sonication on solution properties, morphology, and conductivity of PAN+CB samples.

Oxygen Barrier Properties of Al2O3- and TiO2-coated LDPE Films

Cellulose esters with long carbon side chains (e.g. stearate) were produced via a homogenous reaction in ionic liquids. The degree of substitution was calculated to approximately 2. The melt rheology was studied for the pure cellulose esters but also combinations of the esters and polypropylene to study the processability of a blended composite material. It was shown that the compatibility between the two components was weak, which resulted in a phase-separated composite material. The morphology and permeability of water and oleic acid of the composite films were studied and it was shown that the water permeability decreased upon addition of the cellulose ester to the polymer. The permeability of oleic acid was however unchanged, which is most probable a result of high solubility in the cellulose ester rich domains of the composites. Also, the following hypothesis is stated: cellulose stearate influence the polypropylene crystallization process by decreasing the size of spherulites.

Recycling of PA-12 in Additive Manufacturing and the Improvement of its Mechanical Properties

Current work focuses on establishing optimal growth conditions for covering commercial grade polymer blown films with a gas barrier oxide layer. As opposed to regular solid state substrates, low density polymers host an abundance of free space in the form of pores and voids between large polymer chains (MW > 1000) and a heterogeneous crystallized phase. In the following we will show how the structural peculiarities of the polymer matrix influence the ALD process for growing TiO2 and Al2O3 gas blocking layers on top of the LDPE substrate. Possible causes of low gas barrier performance, thermal expansion coefficient differences, are proposed and commercial process additives, such as slip or antioxidants, are suggested. GRAPHICAL ABSTRACT

Preparation of Cellulose Stearate and Cellulose Acetate Stearate in 1-Butyl-3-Methylimidazolium Chloride

This study explores possible ways to make Additive Manufacturing (AM) a cradle-to-cradle process, that is, use the leftover from one process as the raw material for another process. The main goal of this study is to develop a set of new polymeric blends with innovative properties, suitable for using in 3-D printing of prosthetic limbs using Fused Deposition Modeling (FDM) technology. Sustainable acting is achieved by reusing polymeric material left over from Selective Laser Sintering (SLS) processes for making raw material for FDM processes. Test specimens of polyamide 12 (PA-12) in its virgin form and used- , un-sintered form alongside specimens of used PA blended with TPU, aramid, or graphite, were produced in a micro-injection moulding machine and then tested for their mechanical properties. This paper provides information about the differences in mechanical characteristics of these different material blends. An unexpected but positive finding was that the differences between virgin and recycled PA-12 are insignificant. The aforementioned additives influenced PA-12 by producing specimens that responded with predictable characteristics which is a significant accomplishment as it lays the groundwork for the next stages of the project.

Impact of 1-butyl-3-methylimidazolium chloride on the electrospinning of cellulose acetate nanofibers

Cellulose stearates were prepared in a 1-butyl-3-metylimidazolium chloride ionic liquid. The addition of base pyridine as well as catalyst Tin octoate sufficiently increases the degree of hydroxyl group substitution. The new path for preparation of cellulose mixed esters, namely cellulose acetate stearate (CAS), is performed. The 1H NMR data confirmed the structure of obtained mono- and mix- cellulose esters.

Oxygen Reduction on Catalysts Prepared by Pyrolysis of Electrospun Styrene–Acrylonitrile Copolymer and Multi-walled Carbon Nanotube Composite Fibres

ABSTRACT Additives like ionic liquids (ILs) have proven to be excellent materials useful in improving the electrospinnability and conductivity of both synthetic and biopolymers. The aim of this study is to investigate the effect of 1-buthyl-3-methylimidazolium chloride [BMIM]Cl on the electrospinnability of cellulose acetate (CA). The results showed that [BMIM]Cl has the greater effect on viscosity and conductivity of the spinning solution while the morphology of the nanofibers significantly improved as the concentration of the IL increases from 0% to 12% (v/v) of [BMIM]Cl. To understand the interaction between CA and [BMIM]Cl, Fourier-transform infrared spectroscopy (FTIR) has been used. Observations by scanning electron microscopy (SEM) suggested that [BMIM]Cl significantly altered the morphology of the CA nanofibers and 12% (v/v) of [BMIM]Cl would be an ideal concentration producing uniform fibers with a mean diameter of 180nm. In addition, the membranes showed a significant increase in conductivity (from 0 to 2.21 × 10−7S/cm) as the concentration of ionic liquid increases up to 12% (v/v) that indicates a successful loading of IL inside the nanofibers.

One-step carbon nanotubes grafting with styrene-co-acrylonitrile by reactive melt blending for electrospinning of conductive reinforced composite membranes

For the first time, the oxygen reduction reaction (ORR) is studied on pyrolysed electrospun multi-walled carbon nanotube (MWCNT) and styrene–acrylonitrile (SAN) composite fibre catalysts in alkaline medium. Scanning electron microscopy images revealed that the prepared catalysts mainly consist of MWCNTs, while nitrogen doping of the catalysts is confirmed by X-ray photoelectron spectroscopy. This indicates that SAN can be used as a nitrogen precursor. The ORR studies carried out by rotating disc electrode (RDE) and rotating ring-disc electrode (RRDE) methods showed that the prepared catalysts were considerably more active towards the ORR than the pristine MWCNTs.Graphical Abstract