Air-gap spinning of lignin-cellulose fibers

Co-processing of lignin and cellulose, the two main constituents of wood, has previously been identified as a potential route for the production of inexpensive and bio-based carbon fibers. The first step in this process is to spin a precursor fiber. This can be done with different techniques, and the specific characteristics of air-gap spinning of solutions containing lignin and cellulose were investigated in this work. Studies on how the addition of lignin to a cellulose solution affect the spinnability, the coagulation process, and the fiber structure and properties were performed. In accordance with the hypothesis, it was found that it was possible to gain advantages from both materials, by combining cellulose and lignin. Cellulose is a stiff and linear polymer that contributed to the strength of the fiber, while lignin, with its high carbon content, enhanced the final yield after conversion into carbon fiber. Additionally, solutions that contained both lignin and cellulose could be air-gap spun at substantially higher draw ratios than pure cellulose solutions. This improvement could not be explained with the shear rheology results, however, based on measurements of the take-up force during spinning it was proposed that lignin stabilize against diameter fluctuations during spinning. To analyze how lignin affects the coagulation of lignin-cellulose fibers the total mass transport during coagulation was studied. Different coagulation baths were used, and it was found that minor parts of the lignin leached out, the amount correlated to the lignin solubility in the coagulation bath. Nevertheless, from the results it could also be concluded that the addition of lignin to a cellulose solution did not hinder the coagulation of the fibers. Regarding the fiber structure, it was possible to analyze the molecular order of cellulose and lignin separately and the lignin was found to be completely disordered also in a stretched fiber. In contrast, cellulose attained a preferred molecular orientation even in fibers with high lignin ratios. To further assess the full potential of the system, the lignin-cellulose fibers that were produced were also converted into carbon fibers, and the mechanical properties are promising. In summary, it was considered that lignin-cellulose based carbon fibers have great potential in becoming commercially available if efforts are continued in increasing the strength and stiffness of the fibers even further together with the implementation of efficient solvent recycling

An exhibition on biomedical engineering for Vattenhallen Science Center LTH

This thesis contains the basis for an exhibition about biomedical engineering due to be displayed at Vattenhallen in the summer of 2013. The aim of the exhibition is to inspire and interest the children and adults that come and visits Vattenhallen. Hopefully at least one child will feel interested at study at LTH in the future. The basis contains 13 experimental stations and a short description of a potential laboration. Apart from these 13 stations three experiments have been constructed as well. An EMG-controlled prosthetic hand, an ultrasound phantom in the form of a 13 week old fetus and a software program for an experiment about MR/CT imaging. The experimental stations are: At the hospital Tissues MR Ultrasound The way through the stomach and bowel system Key hole surgery Your fantastic body The EMG controlled hand ECG Tinnitus Dialysis Microfluids The laboration: Servoventilato

ANT-Maps: Visualising Perspectives of Business and Information Systems

In the IS-literature, graphical representations often accompany Actor-Network Theory (ANT) analyses of IS-initiatives, serving as tools for improving visibility of the case and interest and power of actors. Building on a comprehensive literature survey, we identify a gap in existing visualisation approaches, as these mainly focus on offering visual support of the case. We present a visualisation approach and a generic, precise and well defined notation that is directly mapped to key concepts of ANT, highlighting the process of translating actors to commit to the implementation initiative. The approach is illustrated by an actor-network analysis of a particular IS-initiative in a Swedish media organisation

Mechanization in horsestables

Mechanization of Swedish agriculture started in the beginning of the twentieth century, to be able to have more animals without raising the number of employers. The horse business has not by far kept up with these cost savings solutions. Cleaning out stables and feeding horses are the most time-consuming tasks in horse stables today. The most common way to clean out the stable is still by shovel and wheelbarrow. The clean out process can easily be mechanized through semi- permanently beds with movable walls between the boxes so that the litter can be removed by a tractor or a loader. Other ways to simplify manure handling is to mechanize the transport of manure to the storage slab by installing rail-mounted carts or to have scrapers in culverts under the stable floor. A new system on the market for horse stables is Moving Floor™. The floor in the box is moved by compressed air whilst the horse is outdoors during the day, and both the moving of the floor and the filling of litter are controlled by a processor. The feeding process can be mechanized by automatic concentrate feeders or automatic rail-mounted carts, even though the latter still is unusual in horse stables. Loose housing is a way of keeping horses that meets their natural behaviour, and it becomes more common in Sweden. One type of combination of loose housing and mechanized cleaning and feeding is activating stable. The investment costs of these systems are paying off in 0,4 - 5,1 years in a stable with 30 horses. Common costs like processors, culverts and rails make it economically possible for large stables to have a higher level of mechanization

Self-discharge manure systems for dairy cows - farmers' experiences and effects on indoor air quality

Investeringar i mekaniserade utgödslingsanordningar började göras av svenska lantbrukare i mitten på 1900- talet. Med en hög mekaniseringsgrad följer också fler driftstörningar, avbrott och reparationer. Idag hålls över hälften av Sveriges mjölkkor i lösdriftssystem där två typer av golv kan användas – hela och dränerande golv (s.k. spaltgolv). I ladugårdar med dränerande golv kan utgödslingen skötas antingen med skrapor i kulverten under spalten eller med hjälp av att diskvattnet som återvinns ifrån mjölkroboten spolas in under spalten och för med sig gödseln till andra sidan av ladugården, s.k. utgödsling på vattenspegel. Detta system gör att teknik behöver användas i mindre omfattning och därmed minskar eventuellt risken för tekniska stopp och avbrott. Länsstyrelsen i Västra Götalands län har sammanfattat några punkter som antagligen bör följas för att utgödsling på vattenspegel ska fungera tillfredsställande men eftersom utgödslingssystemet är relativt nytt i dagens utformning krävs mer kunskap. Det finns två syften med studien. Det ena är att samla erfarenheter från befintliga stallar och öka kunskapen om den mest fördelaktiga utformningen och skötseln för en väl fungerande utgödsling på vattenspegel i svenska stallar för nötkreatur. Det andra syftet är att undersöka om ammoniakhalten i stalluften i system med utgödsling på vattenspegel skiljer sig från den vid utgödsling med skrapa på helt golv. Enligt en enkät till lantbrukare med utgödsling på vattenspegel kunde ses ett klart samband mellan en tillfredsställande utgödsling och ett ränndjup på minst 80 cm. Ammoniakhalten mättes på fem gårdar med skraputgödsling och på fem gårdar med utgödsling på vattenspegel. Gårdarna besöktes två gånger var och mätningar gjordes på tre olika ställen i ladugården. Ingen signifikant skillnad i medelammoniakhalt i stalluft kunde ses mellan de två utgödslingssystemen.Investments in mechanized manure handling systems started in the mid 2000’s in Sweden. With a higher level of mechanization more disruptions and repairing follows. More than half of Swedish dairy cow population is in loose housing systems where two types of flooring prevail – entire floor and drained floor (known as slatted floor). In barns with drained floors the removal of manure can be managed either with scrapers under the slatted floor or by recycling the dishwater from the milk robot, flushing the manure to the other side of the barn under the floor. This system requires less technology thereby possibly reducing the risk of technical interruptions. A Swedish county administrative board has summarized some points that supposedly should be followed to get the self-discharge system to function optimally, but since the system is relatively new in the current design more knowledge is needed. There are two purposes of this study. The first is to collect experiences from existing barns and increase knowledge about the optimal design and management for well functioning self-discharge manure systems for Swedish dairy cattle. The other purpose is to investigate whether air ammonia concentrations in self-discharge systems are different from barns with solid floor manure scraper systems. According to a questionnaire survey to farmers with self-discharge manure systems a clear correlation could be seen between a well functioning manure system and a distance under the slatted floor of at least 80 cm. Ammonia concentrations were measured at five farms with manure scraper systems and five farms with self-discharge systems. The farms were visited twice each and measurements were done at three different places in the barn. No significant difference could be seen in average air ammonia concentration between the two systems

The challenge of predicting spinnability: Investigating benefits of adding lignin to cellulose solutions in air-gap spinning

In this study, the underlying mechanism for improved spinnability when mixing lignin and cellulose in solution was investigated. Co-processing of lignin and cellulose has previously been identified as a potential route for production of inexpensive and bio-based carbon fibers. The molecular order of cellulose contributes to the strength of the fibers and the high carbon content of lignin improves the yield during conversion to carbon fibers. The current work presents an additional benefit of combining lignin and cellulose; solutions that contain both lignin and cellulose could be air-gap spun at substantially higher draw ratios than pure cellulose solutions, that is, lignin improved the spinnability. Fibers were spun from solutions containing different ratios of lignin, from 0 to 70 wt%, and the critical draw ratio was determined at various temperatures of solution. The observations were followed by characterization of the solutions with shear and elongational viscosity and surface tension, but none of these methods could explain the beneficial effect of lignin on the spinnability. However, by measuring the take-up force it was found that lignin seems to stabilize against diameter fluctuations during spinning, and plausible explanations are discussed

Fluorescence spectra provide information on the depth of fluorescent lesions in tissue

The fluorescence spectrum measured from a fluorophore in tissue is affected by the absorption and scattering properties of the tissue, as well as by the measurement geometry. We analyze this effect with Monte Carlo simulations and by measurements on phantoms. The spectral changes can be used to estimate the depth of a fluorescent lesion embedded in the tissue by measurement of the fluorescence signal in different wavelength bands. By taking the ratio between the signals at two wavelengths, we show that it is possible to determine the depth of the lesion. Simulations were performed and validated by measurements on a phantom in the wavelength range 815-930 nm. The depth of a fluorescing layer could be determined with 0.6-mm accuracy down to at least a depth of 10 mm. Monte Carlo simulations were also performed for different tissue types of various composition. The results indicate that depth estimation of a lesion should be possible with 2-3-mm accuracy, with no assumptions made about the optical properties, for a wide range of tissues

Directed self-assembly of silica nanoparticles in ionic liquid-spun cellulose fibers

The application range of man-made cellulosic fibers is limited by the absence of cost- and manufacturing-efficient strategies for anisotropic hierarchical functionalization. Overcoming these bottlenecks is therefore pivotal in the pursuit of a future bio-based economy. Here, we demonstrate that colloidal silica nanoparticles (NPs), which are cheap, biocompatible and easy to chemically modify, enable the control of the cross-sectional morphology and surface topography of ionic liquid-spun cellulose fibers. These properties are tailored by the silica NPs’ surface chemistry and their entry point during the wet-spinning process (dope solution DSiO2 or coagulation bath CSiO2). For CSiO2-modified fibers, the coagulation mitigator dimethylsulphoxide allows for controlling the surface topography and the amalgamation of the silica NPs into the fiber matrix. For dope-modified fibers, we hypothesize that cellulose chains act as seeds for directed silica NP self-assembly. This results for DSiO2 in discrete micron-sized rods, homogeneously distributed throughout the fiber and for glycidoxy-surface modified DSiO2@GLYEO in nano-sized surface aggregates and a cross-sectional core-shell fiber morphology. Furthermore, the dope-modified fibers display outstanding strength and toughness, which are both characteristic features of biological biocomposites