The hot wire method, with pH and temperature sensors, was evaluated to determine its usefulness and application for cheese production automation. Coagulation of milk substrate was measured with the hot wire instrument and by four other methods: Formagraph, Brookfield®, vixcometer, Omnispec™ bioactivity monitor, and Sommer and Matsen rolling bottle method. The hot wire, using the time at maximum slope, detected coagulation before methods that measure resistance to shear, and after methods that measure light reflectance. Coagulation time was not significantly different from the industry standard rolling bottle method used by Sommer and Matsen. the hot wire instrument was also used to distinguish samples that formed curd at different rates. This was accomplished by measuring the rate of temperature change of the hot wire probe during curd formation. Milk samples of varying protein, fat, and calcium concentrations were prepared to determine if the instrument could be used to predict a consistent curd cut-point. The pH level was also adjusted, and rennet additions were varied. Coagulation was monitored simultaneously with the hot wire system and a Formagraph. All five factors (pH, calcium, fat, protein, and rennet) had significant effects on cut time estimations (CT20) on the Formagraph. Linear correlations (R2) ranging from .74 to .94 were obtained using stepwise regressions when comparing hot wire and compositional data with the Formagraph. A Formagraph was used to measure effects of calcium, pH, and rennet changes on the coagulation properties of late lactation milk. Calcium, pH, and rennet treatments significantly affected the coagulation parameters measured by the Formagraph. However, response among the poor coagulating samples to treatments to improve coagulation was sample dependent. General composition and SDS-PAGE fractionation data could not be used as an indicator of poor or good coagulability of samples. The hot wire method worked well for monitoring coagulation time and curd firming rate, but did not measure maximum curd firmness well. Curd firming rates determined from the hot wire data are acceptable for estimation of a curd cut time. Added benefits of the hot wire method for monitoring cheese manufacture are that stirring, coagulation, and healing of curd can also be measured. Therefore, the rates of change of important parameters, such as pH, temperature, and coagulation during critical processing steps, can easily be determined by a computer and displayed, printed out, or saved for future evaluation.

No description available.

De senaste åren har den globala coworkingtrenden nått Sverige och flertal aktörer har etablerat sig på kontorsmarknaden. Efterfrågan på coworking har vuxit i takt med att allt fler företag önskar flexibilitet i sina avtal och att yngre generationer vill arbeta i en innovativ och kreativ miljö. Det faktum att coworking är ett nytt fenomen har lett till osäkerhet i hur det bör behandlas juridiskt. Den 12 november 2019 publicerade skatterättsnämnden ett förhandsbesked där de beslutar att tillhandahållande av aktivitetsbaserade arbetsplatser ska vara undantagna från skatteplikt. Detta påverkar coworkingbolagen i och med att de inte längre har avdragsrätt för ingående moms hänförlig till de aktivitetsbaserade ytorna. Månaderna efter förhandsbeskedet publicerades, kritiserades det av både coworking- och fastighetsbolag och det är i dagsläget överklagat. Syftet med studien är att utreda vilka effekter förhandsbeskedet kan komma att ha på coworkingbranschen förutsatt att det bifalls.  För att uppfylla studiens syfte har inledningsvis en litteraturstudie genomförts för att samla informationsunderlag gällande coworking, svensk momslagstiftning samt förhandsbeskedet. Vidare genomfördes semistrukturerade intervjuer med coworking- och fastighetsbolag för att få en inblick i de olika parternas tankar och strategier för coworking och förhandsbeskedet. Med resultatet från litteratur- samt intervjustudien som grund har en modell tagits fram för att utreda de ekonomiska effekterna av förhandsbeskedet i olika verksamhetsmodeller för ett coworkingbolag. Resultatet från studien visar på att förhandsbeskedet ökar coworkingbolagens kostnader i samtliga utfall. Detta då all moms som är hänförlig de ytor som upplåts med icke exklusiv rätt blir en kostnad. För att motverka denna kostnadsökning kommer coworkingbolagen behöva omstrukturera sin verksamhet till att upplåta mer yta med exklusiv rätt vilket gör att de rör sig mer mot kontorshotellsliknande koncept. Denna utveckling medför att den del av coworkingbolagens verksamhet som syftar till att skapa samverkan och nätverkande mellan företag blir mindre gångbar att bedriva. / During the last couple of years, the global coworking trend has reached Sweden and several operators has established offices on the real estate market. The demand for coworking has grown following an increase in businesses wanting more flexibility in their leases and the younger generation wanting their work environment to be innovative and creative. The fact that coworking is a new phenomenon has led to difficulties regarding how it should be treated legally. The 12th of November 2019 the Swedish Council for Advance Tax Rulings published a preliminary ruling stating that the providing of activity-based workplaces is to be relived of taxability. This affects coworking businesses since they can no longer deduct VAT on investments related to the activity-based workplaces. The months following the publication the ruling was criticized by both coworking and real estate businesses and it has since been appealed. The purpose of the study is to examine the possible effects of the ruling on the Swedish coworking market, provided that it is approved. To fulfil the purpose of this study a literary study was initially performed to gather information regarding coworking, the Swedish VAT legislation and the preliminary ruling. Following this a series of semi structured interviews was conducted with coworking and real estate businesses to get an insight regarding the thoughts and strategies of the different parties regarding coworking and the preliminary ruling. With the results from the interviews and the literary study a model has been developed to investigate the economic effects of the preliminary ruling in different business models for a coworking business. The result of the study shows that the preliminary ruling will lead to an increase in costs for coworking businesses in all cases. This is because all VAT related to the surfaces that is provided without exclusive right of use becomes a cost. To prevent this increase in costs the coworking businesses will have to restructure their business models to provide more office space with exclusive right. This leads to Swedish coworking businesses moving more towards an office hotel business model. This development results in that the part of the coworking businesses that aim to provide cooperation and networking between members becomes less viable.

The curing characteristics of photopolymer resin determine the relationship between the vat polymerization (VP) process parameters and the layer thickness, geometric accuracy, and surface quality of the 3D printed specimen. Dispersing filler material into the photopolymer resin changes its curing characteristics because the filler scatters and absorbs light, which modifies the curing reaction. However, the ability to cure photopolymer resin with high filler volume fraction is important to 3D print material specimens for specific engineering applications, e.g. structural polymer composite materials, electrical and thermal conductive materials, and ceramic materials for biological and high-temperature environments. We methodically measure the curing characteristics of diacrylate/epoxy photopolymer resin with dispersed glass microspheres. The experiments show that the curing depth, degree-of-cure, and surface roughness depend on both the light exposure dose and the filler fraction. We determine that the degree-of-cure increases with increasing filler fraction for constant exposure dose, and approaches 90% with increasing exposure dose, independent of the filler fraction. The geometric accuracy of the 3D printed specimens decreases with increasing exposure dose and with increasing filler volume fraction due to so-called profile broadening. Finally, we show that the average surface roughness of the 3D printed specimens decreases with increasing exposure dose and filler fraction. This work has implications for VP of photopolymer resins with high filler fraction. / Master of Science / Photopolymer resin is a gel-like liquid material that hardens (cures) into solid after absorbing light energy, and such a material is often used in the field of additive manufacturing (3D printing) to create complex geometry. Certain types of filler materials, such as metal powder or carbon fiber, can be added into the photopolymer resin to tailor the material properties, and thus, affects the curing behavior of photopolymer resin mixed with these filler materials. We conducted an experiment to understand how adding glass microspheres to a consumer grade photopolymer resin affects the process of creating 3D objects. This is important in the context of 3D printing engineered composite materials that derive their function from the organization and orientation of filler material in a matrix. To do this, we created many samples in the shape of a "VT" logo using the composite resin we made and measured their thickness (curing depth), degree-of-cure, surface roughness, and geometric accuracy, as a function of the amount of light energy being exposed to the resin (exposure dose) and the amount of the glass filler being added into the resin (filler fraction). We observed that when we increased the amount of light exposure, it resulted specimens that are thicker and more in degree of cure. Adding the glass filler to the liquid had mixed effects on the hardening process, because glass can scatter light and change how light travels within the resin. As a result, the printed objects became less accurate in shape and have smoother surface with increasing exposure dose and filler fraction, because more light is scattered off the designed curing profile and unintentionally cured the surrounding resin.

The reliance on low-viscosity and photoactive resins limits the accessible properties for vat photopolymerization (VP) materials required for engineering applications. This has limited the adoption of VP for producing end-use parts, which typically require high MW polymers and/or more stable chemical functionality. Decoupling the viscosity and molecular weight relationship for VP resins has been completed recently for polyimides and highperformance elastomers by photocuring a scaffold around polymer precursors or polymer nanoparticles, respectively. Both of these materials are first shaped by printing a green part followed by thermal post-processing to achieve the final part properties. This dissertation focuses on improving the processability of these material systems by (i) investigating the impact of scaffold architecture and polysalt monomer composition on photocuring, thermal post-processing, and resulting thermomechanical properties and (ii) developing a Monte Carlo ray-tracing (MCRT) simulation to predict light scattering and photocuring behavior in particle-filled resins, specifically zinc oxide nanoparticles in a rigid polyester resin and styrene butadiene rubber latex resin. The first portion of the dissertation introduces VP of a tetra-acid and half-ester-based polysalt resin derived from 4,4'-oxydiphthalic anhydride and 4,4-oxydianiline (ODPA-ODA), a fully aromatic polyimide with high glass transition temperature and thermal stability. This polyimide, and polyimides like this, find use in demanding industries such as aerospace, automotive and electronic applications. The author evaluated the hypothesis that a non-bound triethylene glycol dimethacrylate (TEGDMA) scaffold would facilitate more efficient scaffold burnout and thus achieve parts with reduced off-gassing potential at elevated temperatures. Both resins demonstrated photocuring and were able to print solid and complex latticed parts. When thermally processed to 400 oC, only 3% of the TEGDMA scaffold remained within the final parts. The half-ester resin exhibits higher char yield, resulting from partial degradation of the polyimide backbone, potentially caused by lack of solvent retention limiting the imidization conversion. The tetra-acid exhibits a Tg of 260oC, while the half-ester displays a higher Tg of 380 oC caused by the degradation of the polymer backbone, forming residual char, restricting chain mobility. Solid parts displayed a phase-separated morphology while the half-ester latticed parts appear solid, indicating solvent removal occurs faster in the half-ester composition, presumably due to reduced polar acid functionality. This platform and scaffold architecture enables a modular approach to produce novel and easily customizable UV-curable polyimides to easily increase the variety of polyimides and the accessible properties of printed polyimides through VP. The second section of this dissertation describes the creation and validation of a MCRT simulation to predict light scattering and the resulting photocured shape of a ZnO-filled resin nanocomposite. Relative to prior MCRT simulations in the literature, this approach requires only simple, easily acquired inputs gathered from dynamic light scattering, refractometry, UV-vis spectroscopy, beam profilometry, and VP working curves to produce 2D exposure distributions. The concentration of 20 nm ZnO varied from 1 to 5 vol% and was exposed to a 7X7 pixel square ( 250 µm) from 5 to 11 s. Compared to experimentally produced cure profiles, the MCRT simulation is shown to predict cure depth within 10% (15 µm) and cure widths within 30% (20 µm), below the controllable resolution of the printer. Despite this success, this study was limited to small particles and low loadings to avoid polycrystalline particles and maintain dispersion stability for the duration of the experiments. Expanding the MCRT simulation to latex-based resins which are comprised of polymer nanoparticles that are amorphous, homogeneous, and colloidally stable. This allows for validating the MCRT with larger particles (100 nm) at higher loadings. Simulated cure profiles of styrene-butadiene rubber (SBR) loadings from 5 vol% to 25 vol% predicted cure depths within 20% ( µm) and cure widths within 50% ( µm) of experimental values. The error observed within the latex-based resin is significantly higher than in the ZnO resin and potentially caused by the green part shrinking due to evaporation of the resin's water, which leads to errors when trying to experimentally measure the cure profiles. This dissertation demonstrates the development of novel and functional materials and creation process-related improvements. Specifically, this dissertation presents a materials platform for the future development of unique photocurable engineering polymers and a corresponding physics-based model to aid in processing. / Doctor of Philosophy / Vat Photopolymerization (VP) is a 3D printing process that uses ultraviolet (UV) light to selectively cure liquid photosensitive resin into a solid part in a layer-by-layer fashion. Parts produced with VP exhibit a smooth surface finish and fine features of less than 100 µm (i.e., width of human hair). Recoating the liquid resin for each layer limits VP to low-viscosity resins, thus limiting the molecular weight (and thus performance) of the printed polymers accessible. Materials that are low molecular weight are limited in achieving desirable properties, such as elongation, strength, and heat resistance. Solvent-based resins, such as polysalt and latex resins have demonstrated the ability to decouple the viscosity and molecular weight relationship by eliminating polymer entanglements using low-molecular-weight precursors or isolating high-molecular-weight polymers into particles. This dissertation focuses on expanding and improving the printability of these methods. The second chapter of the dissertation investigates the impact of scaffold architecture in printing polyimide polysalts to improve scaffold burnout. Polysalts are polymers that exist as dissolved salts in solution, with each monomer holding two electronic charges. When heated, the solvent evaporates and the monomers react to form a high molecular-weight polymer. While previous work featured a polysalt that was covalently bonded to the monomers, the polysalt in this work is made printable by co-dissolving a scaffold. The polysalt resins are photocured and thermally processed to polymerize and imidize into a high-molecular-weight polymer, while simultaneously pyrolyzing the scaffold. Using a co-dissolved scaffold allows the investigation of two different monomers of tetra-acid and half-ester functionality. The half-ester composition underwent degradation during heating, increasing the printed parts' glass transition or softening point. The scaffold had little impact on the polysalt polymerization or final part properties and was efficiently removed, with only 3% remaining in final parts. The composition and properties of the monomers selected played a bigger role due to partial degradation altering the properties of the final parts. Overall, this platform and scaffold architecture allows for a larger number of polyimides to be accessible and easily customizable for future VP demands. The third chapter describes the challenges of processing photocurable resins that contain particles due to the UV light scattering in the resin vat during printing. When the light from the printer hits a particle, it is scattered in all directions causing the layer shape to be distorted from the designed shape. To overcome this, a Monte Carlo ray-tracing (MCRT) simulation was developed to mimic light rays scattering within the resin vat. The simulation was validated by comparing simulation results against experiment trials of photocuring resins containing 20nm zinc oxide (ZnO) nanoparticles. The MCRT simulation predicted all the experimental cure depths within 10% (20 µm) and cured widths within 30% (15 µm) error. Despite the high accuracy, this study was limited to small particles and low concentrations. Simulating larger particles is difficult as the simulation assumes each particle to be uniform throughout its volume, which is atypical of large ceramic particles. The fourth chapter enables high particle volume loading by using a highly stretchable styrene-butadiene rubber (SBR) latex-based resin. Latex-based resins maintain low viscosity by separating large polymer chains into nano-particles that are noncrystalline and uniform. When the chains are separated, they cannot interact or entangle, keeping the viscosity low even at high concentrations (>30 vol%). Like the ZnO-filled resin, the latex resin is experimentally cured and the MCRT simulation predicts the resulting cure shape. The MCRT simulation predicted cure depths within 20% (100 µm) and over-cure widths within 50% (100 µm) of experimental values. This error is substantially higher than the ZnO work and is believed to be caused by the water evaporating from the cured resin resulting in inconsistent measurements of the cured dimensions.

Uppsatsen syftar till att undersöka regelverket kring och riskerna med momsfördelningstal och den frivilliga skattskyldigheten för mervärdesskatt i allmänhet. Utöver undersökningen har även tillämpningen av momsfördelningstal och de faktiska konsekvenserna påvisats genom exemplifiering, intervjuer och studerande av litteratur på området. Uppsatsen följer den rättsdogmatiska metoden, ett inifrån- och utperspektiv. Vad säger lagen och vilka påföljder och konsekvenser innebär den? Läsaren kommer få en inblick i de risker som fastighetsbranschen står inför med den gällande lagstiftningen.Mervärdesskatten är en indirekt konsumtionsskatt. Systemet bygger på att näringsidkare övervältrar skattekostnaden på slutkonsumenten, för att driva in beloppet till staten. Tanken är att moms inte ska vara en kostnad för momsregistrerade företag, då de kan göra avdrag för den ingående momsen och på det sättet få tillbaka pengarna. Fastighetsområdet är normalt sett undantaget skatteplikt men det finns sedan 1979 möjlighet att ansöka om frivillig skattskyldighet för mervärdesskatt. Detta gäller endast lokaler som är uthyrda till skattepliktig verksamhet och inte bostäder.I de fall där en fastighet inrymmer både skattepliktig verksamhet och bostäder får fullt avdrag för ingående skatt endast göras i delar som är verksamhetslokaler. För de kostnader som berör gemensamma ytor t.ex. uppvärmning, vatten, ventilation mm. får endast avdrag göras efter en viss procentsats, ett s.k. fördelningstal. Detta fördelningstal ska vara av skälig grund.Det regelverk som finns idag är komplicerat och inrymmer undantag som gör det administrativt betungande för företag och myndigheter. Kännedomen inom fastighetsbranschen är många gånger bristfällig. Används momsfördelningstal korrekt kan det vara ekonomiskt fördelaktigt, men den bristfälliga kännedomen i kombination med det komplexa regelverket gör att risker uppstår. Risker som har rättsliga och ekonomiska konsekvenser.Genom intervju med Skatteverket samt två företag inom branschen har författarna bekräftat att det finns problem med den allmänna kännedomen och att de risker som tas upp i denna uppsats är riktiga. Den största risken är den i allmänhet låga kännedomen om reglerna, samtidigt som de flesta tror sig besitta den nödvändiga kunskapen. Det leder ofta till att oriktiga uppgifter kommer in till Skatteverket och att den som gör felet får skattetillägg som slutlig konsekvens. Det är vår uppfattning, och de parter vi varit i kontakt med, att införandet av en obligatisrisk skattskyldighet är nödvändig. / The purpose of this report is to study the regulations and risks governing VAT-sharing keys and the voluntary VAT in general. In addition to this the application of VAT-sharing keys and the consequences of using them wrongly has been detected through exemplification, interviews and studying the literature. The report is written using legal dogmatic method. What penalties does present legislation mean? The reader will be shown the risks that the industry is facing with the current regulations.The value added tax system is an indirect consumption tax. It is based on the principle that traders and businesses pass on the tax fee to the final consumer, to collect the taxes for the government. These businesses are not meant to pay VAT and are able to deduct for the ingoing VAT amount, and get their tax back this way. The property market is generally exempt taxes but since 1979 property owners has been able to apply for voluntary value added tax. This goes for renting to legitimate traders and businesses only, not accommodation renting.In some cases the tenants are both traders and residents in one and the same property. The ingoing tax is fully deductible only for the parts that are rented to businesses in these cases. The tax from costs concerning the joint areas or joint operation costs like heating, ventilation, water etc. can only be deducted by using a so called sharing key. The sharing key has to be of reasonable grounds.Today’s regulations are complicated and have a considerable amount of exceptions and they make it administratively burdensome for businesses and authorities. The knowledge within the property industry is oftentimes inadequate. When used correctly, VAT-sharing keys can be economically advantageous, but because of the short knowledge and the complex regulations there are a lot of risks, risks that have jurisdictional and economic consequences.By interviewing the Swedish tax authorities (Skatteverket) along with two businesses in the property industry the writers have confirmed that there are problems with the general knowledge and that the risks that have been raised are real. The biggest risk is the one involving the generally inadequate knowledge, combined with the unawareness of it. This leads to a lot of incorrect information being sent to Skatteverket with added tax fines as a result.

VAT plays a crucial role in creating a single internal market in the EU. However, the applicability of VAT rules in regard to the conduct of clinical trials and investigational medicinal products (IMPs) remains uncertain due to different interpretations among the Member States and the lack of case laws regarding clinical trials. This thesis examines the EU VAT Directive and the case law provided by the ECJ using a teleological approach to interpret the concept of medical care and identify applicable provisions for the conduct of clinical trials and transactions involving IMPs. The analysis provides insights into the VAT treatment of clinical trials conducted within the EU.

Additive manufacturing (AM) creates 3D objects out of polymers, ceramics, and metals to enable cost-efficient and rapid production of products from aerospace to biomedical applications. Personalized products manufactured using AM, such as personalized dosage pharmaceuticals, tissue scaffolds, and medical devices, require specific material properties such as biocompatibility and biodegradability, etc. Polymers possess many of these qualities and tuning molecular structure enables a functional material to successfully deliver the intended application. For example, water-soluble polymers such as poly(vinyl pyrrolidone) and poly(ethylene glycol) both function as drug delivery materials because of their inherit water-solubility and biocompatibility. Other polymers such as polylactide and polyglycolide possess hydrolytically cleavable functionalities, which enables degradation in the body. Non-covalent bonds, such as hydrogen bonding and electrostatic interactions, enable strong connections capable of holding materials together, but disconnect with heat or solvation. Taking into consideration some of these polymer functionalities, this dissertation investigates how to utilize them to create functional biomedical products using AM. The investigation of structure-property-processing relationships of polymer molecular structures, physical properties, and processing behaviors is transforming the field of new materials for AM. Even though novel, functional materials for AM continue to be developed, requirements that render a polymeric material printable remain unknown or vague for most AM processes. Materials and printers are usually developed separately, which creates a disconnect between the material printing requirements and fundamental physical properties that enable successful printing. Through the interface of chemistry, biology, chemical engineering, and mechanical engineering, this dissertation aims to relate printability of polymeric materials with three types of AM processes, namely vat photopolymerization, binder jetting, and powder bed fusion. Binder jetting, vat photopolymerization, and powder bed fusion require different viscosity and powder requirements depending on the printer capabilities, and if the material is neat or in solution. Developing scaling relationships between solution viscosity and concentration determined critical overlap (C*) and entanglement (Ce) concentrations, which are related to the printability of the materials. For example, this dissertation discusses and investigates the maximum printable concentration in binder jetting of multiple polymer architectures in solution as a function of C* values of the polymer. For thermal-type printheads, C* appeared to be the highest jettable concentration, which asserted an additional method of material screening for binder jetting. Another investigation of the photokinetics as a function of concentration of photo-active polymers in solution revealed increased viscosity leads to decreased acrylate/acrylamide conversion. Lastly, investigating particle size and shape of poly(stearyl acrylate) particles synthesized through suspension polymerization revealed a combination of crosslinked and linear polymers produced high resolution parts for phase change materials. These analytical screening methods will help the progression of AM and provide future scientists and engineers a better guideline for material screenings. / Doctor of Philosophy / Additive manufacturing (AM), also known as 3D printing, enables the creation of 3D objects in a rapid and cost-efficient manner for applications from aerospace to biomedical sectors. AM particularly benefits the field of personalized biomedical products, such as personalized dosage pharmaceuticals, hearing aids, and prosthetic limbs. In the future, advanced detection and prevention medical screenings will provide doctors, pharmacists, and engineers very precise data to enable personalized healthcare. For example, a patient can take three different medications in one pill with the exact dosage to prevent side-effects and drug-drug interactions. AM enables the delivery and manufacturing of these personalized systems and will improve healthcare in every sector. Investigations of the most effective materials is needed for personalized medicine to become a reality. Polymers, or macromolecules, provide a highly tunable material to become printable with slight chemical modifications. Investigation of how chemical structure affects properties, such as strength, stretchability, or viscosity, will dictate how they perform in a manufacturing setting. This process of investigation is called "structure-property-processing" relationships, which connects scientists and engineers through all disciplines. This method is used to discover which polymers will not only 3D print, but also carry medication to a patient or deliver therapeutics within the body.

In recent years, triply periodic minimal surfaces (TPMS) have drawn much attention in research mainly due to their smooth, highly symmetrical surfaces, non-self-intersecting features, and mathematically controllable topologies. TPMS can have pre-defined physical and mechanical properties. The advancement of additive manufacturing technology enables us to fabricate these intricate geometric structures which was not possible by traditional manufacturing methods. In this study, the vat photopolymerization technique was used to manufacture Primitive, Gyroid, and Diamond structures. Samples were cured under ultraviolet (UV) rays after printing. Uniaxial compression experiments were conducted to assess the compressive modulus and strength of these lightweight structures. The compressive behavior of TPMS structures was also predicted using finite element analysis (FEA). Dynamic mechanical analysis (DMA) was used to compare the behavior of these structures at different temperatures. UV-cured samples exhibited improved thermo-mechanical characteristics. The primitive structure had the highest compressive strength among other structures. FEA also revealed the stress concentration areas for each sandwich structure. The DMA findings indicate that TPMS sandwich structures demonstrate significantly reduced storage modulus compared to solid structures. A numerical investigation was performed to understand the heat exchanger application of TPMS structures. The velocity profile, temperature, and pressure distributions were observed for the Primitive heat exchanger. The results of this investigation provide valuable information regarding the enhanced structural and thermal characteristics of these structures manufactured using vat photopolymerization.

As cores sempre exerceram fascínio sobre a humanidade e, por toda a história, os compostos coloridos sempre foram considerados ferramentas atrativas nas atividades comerciais. Os corantes sintéticos são amplamente utilizados na indústria têxtil, nas impressões de papel e fotografia, nas indústrias farmacêuticas, alimentícias e de cosméticos. Estes compostos são considerados importantes contaminantes ambientais, representando sérios riscos à flora, fauna e ao ser humano. Apesar da grande quantidade de corantes disponíveis, os estudos sobre a toxicidade desses compostos são escassos e pouco se sabe a respeito dos efeitos genotóxicos destas substâncias. Dentro deste contexto, o presente trabalho avaliou o potencial genotóxico dos corantes Sudan III, Vat Green 3, Reactive Orange 16 e Reactive Black 5, utilizando o Ensaio de Micronúcleos em células HepG2. Os corantes Sudan III e Reactive Orange 16 não induziram aumento, estatisticamente significativo, no número total de micronúcleos em relação aos controles, indicando assim que estes corantes não são capazes de induzir mutações cromossômicas no tipo celular e condições testadas. Entretanto, os corantes Vat Green 3 e Reactive Black 5 induziram mutagenicidade, concentrações de 10,0 e 25,0 ?g/mL, e 0,1; 0,25; 0,5 e 1,0 ?g/mL, respectivamente, demonstrada por um efeito concentraçãodependente, no qual há um aumento de MNs até a concentração de 25,0 ?g/mL para o Vat Green 3 e 0,5 ?g/mL para o Reactive Black 5 com p<0,05. Não foram observadas diferenças significativas entre os IDNs calculados para cada tratamento e controle dos corantes testados, indicando que esses corantes não interferem na proliferação celular das HepG2. Dessa forma, conclui-se que dos quatro compostos analisados, os corantes têxteis Vat Green 3 e Reactive Black 5 são capazes de induzir mutações cromossômicas em células HepG2 e, o potencial mutagênico do Reactive Black 5 é maior que o do Vat Green 3 no sistema celular avaliado, uma vez que foi capaz de induzir mutações, em concentrações menores. Os resultados obtidos neste trabalho permitem concluir que cada um desses importantes contaminantes ambientais deve ser avaliado individualmente a fim de proteger o meio ambiente, garantindo assim a proteção da saúde humana. / The colors have always caused fascination in mankind. Throughout history, colored compounds have always been considered attractive tools in industrial activities. The synthetic dyes are widely used in textile industry, paper and photography printing, in pharmaceutical, food, and cosmetic industries. These compounds are considered important environmental contaminants, and they can cause serious risks to wildlife and humans. Despite the large number of dyes available, studies on the toxicity of these compounds are scarce and little is known about the genotoxic effects of these substances. This study evaluated the genotoxic potential of the dyes Sudan III, Vat Green 3, Reactive Orange 16 and Reactive Black 5 using the micronucleus assay in HepG2 cells. The dyes Sudan III and, Reactive Orange 16, do not induce an increase statistically significant, in the total number of micronuclei when compared to controls. This result shows that these dyes are not able to induce chromosomal mutations in the cell type under the conditions tested. However, the dyes Vat Green 3 and Reactive Black 5 induced mutagenicity, following a dose-response effect, in which there is an increase of micronuclei until the concentration of 25.0 ?g/mL for Vat Green 3 and 0.5 ?g/mL for Reactive Black 5, with p <0.05. There were no significant differences between the NDI calculated for each treatment and control of the dyes studied, indicating that these dyes do not interfere in HepG2 cell proliferation. Thus, the textile dyes Vat Green 3 and Reactive Black 5 are able to induce chromosomal mutations in HepG2 cells, and the dye Reactive Black 5 is more mutagenic than the dye Vat Green 3, since it induced mutations in cellular system tested at lower concentrations. The results of this study indicate that each one of these important environmental contaminants should be assessed individually in order to protect the environment, thus ensuring the protection of human health.