Influence of belt speed, grit sizes and pressure on the sanding of Eucalyptus grandis wood

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of belt speed, pressure and grit size on the sanding of pinus elliottii wood

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

High-aspect-ratio tridimensional electrode arrays for neural applications

Tese de Doutoramento em Engenharia Biomédica.

Rhinitis due to acrylates : case report

Background: Acrylates and methacrylates (salts and esters of acrylic and metacrylic acid respectively), are monomers commonly found in polymer plastics, resins and glues, and are widely used in many industry sectors. The first adverse health effects described were skin reactions and asthma. Exposure to acrylates, for instance when using multicomponent glues, is now a well known cause of occupational asthma. Methods: We report the case of a rhinitis - and possible asthma - to acrylates, in a 38-year-old woman, working in a nail beauty salon. She was currently treated for hypertension, and otherwise known for obesity and seasonal rhinoconjunctivitis, but did not have any respiratory problem. Two years after starting this activity, she progressively started to complain of anosmia, rhinitis, and intermittent dyspnea. Her job consisted in decorating nails with a mixture of a polymer powder and a liquid monomer, after removing the previous artificial nail with a small sander. We assessed exposure to acrylates at her working place, both as dust (from sanded nails) and volatile compound (from the mixture described above), and she was asked to measure her peak flow values twice a day for ten days, in order to detect a possible relationship between her occupational activities, the symptoms and the peak flow values. Results: Measures made during the visit of the patient's place of work showed that the existing aspiration system was efficient for eliminating the dust produced by nail sanding, but not for eliminating the volatile components. Thus, occupational exposure to acrylates was demonstrated. Moreover, the peak flow measures showed an average decrease of almost 10 percent when the patient was at work, compared to when she stayed home. We concluded that she actually suffered from professional rhinitis and, possibly, professional asthma (not certain because of the limited number of peak flow measures per day). Conclusion: Although exposure to acrylates is a well known cause of occupational asthma, it should be emphasized that the exact mechanisms of action remain unknown, despite the abundant literature about it. Some professions, which tend to be more frequent nowadays (such as working in a nail beauty salon), can expose the worker to particular risks. This highlights the need of always inquiring not only about the profession, but also the related activities, when facing a case of suspected asthma.

Field Measurements of Plow Loads During Ice Removal Operations, HR-334, 1993

One of the more severe winter hazards is ice or compacted snow on roadways. While three methods are typically used to combat ice (salting, sanding and scraping), relatively little effort has been applied to improve methods of scraping ice from roads. In this project, a new test facility has been developed, comprising a truck with an underbody blade, which has been instrumented such that the forces to scrape ice from a pavement can be measured. A test site has been used, which is not accessible to the public, and ice covers have been sprayed onto the pavement and subsequently scraped from it, while the scraping loads have been recorded. Three different cutting edges have been tested for their ice scraping efficiency. Two of the blades are standard (one with a carbide insert, the other without) while the third blade was designed under the SHRP H-204A project. Results from the tests allowed two parameters to be identified. The first is the scraping efficiency which is the ratio of vertical to horizontal force. The lower this ratio, the more efficiently ice is being removed. The second parameter is the scraping effectiveness, which is related (in some as yet unspecified manner) to the horizontal load. The higher the horizontal load, the more ice is being scraped. The ideal case is thus to have as high a horizontal load as possible, combined with the lowest possible vertical load. Results indicate that the SHRP blade removed ice more effectively than the other two blades under equivalent conditions, and furthermore, did so with greater efficiency and thus more control. Furthermore, blade angles close to 0 deg provide for the most efficient scraping for all three blades. The study has shown that field testing of plow blades is possible in controlled situations, and that blades can be evaluated using this system. The system is available for further tests as are deemed appropriate.

The Use of Abrasives in Winter Maintenance, TR-434, 2001

The use of abrasives in winter maintenance is a well-established practice. The sand or other abrasive is intended to increase friction between vehicles and the (often snow or ice covered) pavement. In many agencies (and in many Iowa Counties, the focus of this study) the use of sand is a standard part of winter maintenance. Yet very little information exists on the value of sanding as a winter maintenance procedure. Some studies suggest that friction gains from sanding are minimal. In addition, there are increasing environmental concerns about sanding. These concerns focus on air quality and stormwater quality issues. This report reviews the state of the practice of abrasive usage in Iowa Counties, and classifies that usage according to its effectiveness. Possible changes in practice (with respect to abrasive usage) are presented and discussed.

Etude des niveaux de concentration d'hydrocarbures aromatiques polycycliques (HAPs) dans la poussière de bois et des marqueurs biologiques d'effets génotoxiques chez les travailleurs du bois

L'exposition aux poussières de bois est associé à un risque accru d'adénocarcinomes des fosses nasales et des sinus paranasaux (SNC, 'Sinonasal cancer') chez les travailleurs du bois. Les poussières de bois sont ainsi reconnues comme cancérogènes avérés pour l'homme par le Centre international de Recherche sur le Cancer (CIRC). Toutefois, l'agent causal spécifique et le mécanisme sous-jacent relatifs au cancer lié aux poussières de bois demeurent inconnus. Une possible explication est une co-exposition aux poussières de bois et aux Hydrocarbures Aromatiques Polycycliques (HAP), ces derniers étant potentiellement cancérogènes. Dans les faits, les travailleurs du bois sont non seulement exposés aux poussières de bois naturel, mais également à celles générées lors d'opérations effectuées à l'aide de machines (ponceuses, scies électriques, etc.) sur des finitions de bois (bois traités) ou sur des bois composites, tels que le mélaminé et les panneaux de fibres à densité moyenne (MDF, 'Medium Density Fiberboard'). Des HAP peuvent en effet être générés par la chaleur produite par l'utilisation de ces machines sur la surface du bois. Les principaux objectifs de cette thèse sont les suivants: (1) quantifier HAP qui sont présents dans les poussières générées lors de diverses opérations courantes effectuées sur différents bois (2) quantifier l'exposition individuelle aux poussières de bois et aux HAP chez les travailleurs, et (3) évaluer les effets génotoxiques (dommages au niveau de l'ADN et des chromosomes) due à l'exposition aux poussières de bois et aux HAP. Cette thèse est composée par une étude en laboratoire (objectif 1) et par une étude de terrain (objectifs 2 et 3). Pour l'étude en laboratoire, nous avons collecté des poussières de différents type de bois (sapin, MDF, hêtre, sipo, chêne, bois mélaminé) générées au cours de différentes opérations (comme le ponçage et le sciage), et ceci dans une chambre expérimentale et dans des conditions contrôlées. Ensuite, pour l'étude de terrain, nous avons suivi, dans le cadre de leur activité professionnelle, 31 travailleurs de sexe masculin (travailleurs du bois et ébenistes) exposés aux poussières de bois pendant deux jours de travail consécutifs. Nous avons également recruté, comme groupe de contrôle, 19 travailleurs non exposés. Pour effectuer une biosurveillance, nous avons collecté des échantillons de sang et des échantillons de cellules nasales et buccales pour chacun des participants. Ces derniers ont également rempli un questionnaire comprenant des données démographiques, ainsi que sur leur style de vie et sur leur exposition professionnelle. Pour les travailleurs du bois, un échantillonnage individuel de poussière a été effectué sur chaque sujet à l'aide d'une cassette fermée, puis nous avons évalué leur exposition à la poussière de bois et aux HAP, respectivement par mesure gravimétrique et par Chromatographie en phase gazeuse combinée à la spectrométrie de masse. L'évaluation des dommages induits à l'ADN et aux chromosomes (génotoxicité) a été, elle, effectuée à l'aide du test des micronoyaux (MN) sur les cellules nasales et buccales et à l'aide du test des comètes sur les échantillons de sang. Nos résultats montrent dans la poussière de la totalité des 6 types de bois étudiés la présence de HAP (dont certains sont cancérogènes). Des différences notoires dans les concentrations ont été néanmoins constatées en fonction du matériau étudié : les concentrations allant de 0,24 ppm pour la poussière de MDF à 7.95 ppm pour le mélaminé. Nos résultats montrent également que les travailleurs ont été exposés individuellement à de faibles concentrations de HAP (de 37,5 à 119,8 ng m-3) durant les opérations de travail du bois, alors que les concentrations de poussières inhalables étaient relativement élevés (moyenne géométrique de 2,8 mg m-3). En ce qui concerne la génotoxicité, les travailleurs exposés à la poussière de bois présentent une fréquence significativement plus élevée en MN dans les cellules nasales et buccales que les travailleurs du groupe témoin : un odds ratio de 3.1 a été obtenu pour les cellules nasales (IC 95% : de 1.8 à 5.1) et un odds ratio de 1,8 pour les cellules buccales (IC 95% : de 1.3 à 2.4). En outre, le test des comètes a montré que les travailleurs qui ont déclaré être exposés aux poussières de MDF et/ou de mélaminé avaient des dommages à l'ADN significativement plus élevés que les deux travailleurs exposés à la poussière de bois naturel (sapin, épicéa, hêtre, chêne) et que les travailleurs du groupe témoin (p <.01). Enfin, la fréquence des MN dans les cellules nasales et buccales augmentent avec les années d'exposition aux poussières de bois. Par contre, il n'y a pas de relation dose-réponse concernant la génotoxicité due à l'exposition journalière à la poussière et aux HAP. Cette étude montre qu'une exposition aux HAP eu bien lieu lors des opérations de travail du bois. Les travailleurs exposés aux poussières de bois, et donc aux HAP, courent un risque plus élevé (génotoxicité) par rapport au groupe témoin. Étant donné que certains des HAP détectés sont reconnus potentiellement cancérogènes, il est envisageable que les HAP générés au cours du travail sur les matériaux de bois sont un des agents responsables de la génotoxicité de la poussière de bois et du risque élevé de SNC observé chez les travailleurs du secteur. Etant donné la corrélation entre augmentation de la fréquence des MN, le test des micronoyaux dans les cellules nasales et buccales constitue sans conteste un futur outil pour la biosurveillance et pour la détection précoce du risque de SNC chez les travailleurs. - Exposures to wood dust have been associated with an elevated risk of adenocarcinomas of the Dasal cavity and the paranasal sinuses (sinonasal cancer or SNC) among wood workers. Wood dust is recognized as a human carcinogen by the International Agency for Research on Cancer. However, the specific cancer causative agent(s) and the mechanism(s) behind wood dust related carcinogenesis remains unknown. One possible explanation is a co-exposure to wood dust and polycyclic aromatic hydrocarbons (PAH), the latter being carcinogenic. In addition, wood workers are not only exposed to natural wood but also to wood finishes and composite woods such as wood melamine and medium density fiber (MDF) boards during the manipulation with power tools. The heat produced by the use of power tools can cause the generation of PAH from wood materials. The main objectives of the present thesis are to: (1) quantify possible PAH concentrations in wood dust generated during various common woodworking operations using different wood materials; (2) quantify personal wood dust concentrations and PAH exposures among wood workers; and (3) assess genotoxic effects (i.e., DNA and chromosomal damage) of wood dust and PAH exposure in wood workers. This thesis is composed by a laboratory study (objective 1) and a field study (objectives 2 and 3). In the laboratory study we collected wood dust from different wood materials (fir, MDF, beech, mahagany, oak, and wood melamine) generated during different wood operations (e.g., sanding and sawing) in an experimental chamber under controlled conditions. In the following field study, we monitored 31 male wood workers (furniture and construction workers) exposed to wood dust during their professional activity for two consecutive work shifts. Additionally, we recruited 19 non exposed workers as a control group. We collected from each participant blood samples, and nasal and buccal cell samples. They answered a questionnaire including demographic and life-style data and occupational exposure (current and past). Personal wood dust samples were collected using a closed-face cassette. We used gravimetrie analysis to determine the personal wood dust concentrations and capillary gas chromatography - mass spectrometry analysis to determine PAH concentrations. Genotoxicity was assessed with the micronucleus (MN) assay for nasal and buccal cells and with the comet assay for blood samples. Our results show that PAH (some of them carcinogenic) were present in dust from all six wood materials tested, yet at different concentrations depending on the material. The highest concentration was found in dust from wood melamine (7.95 ppm) and the lowest in MDF (0.24 ppm). Our results also show that workers were individually exposed to low concentrations of PAHs (37.5-119.8 ng m"3) during wood working operations, whereas the concentrations of inhalable dust were relatively high (geometric mean 2.8 mg m"3). Concerning the genotoxicity, wood workers had a significantly higher MN frequency in nasal and buccal cells than the workers in the control group (odds ratio for nasal cells 3.1 (95%CI 1.8-5.1) and buccal cells 1.8 (95%CI 1.3-2.4)). Furthermore, the comet assay showed that workers who reported to be exposed to dust from wooden boards (MDF and wood melamine) had significantly higher DNA damage than both the workers exposed to natural woods (fir, spruce, beech, oak) and the workers in the control group (p < 0.01). Finally, MN frequency in nasal and buccal cells increased with increasing years of exposure to wood dust. However, there was no genotoxic dose-response relationship with the per present day wood dust and PAH exposure. This study shows that PAH exposure occurred during wood working operations. Workers exposed to wood dust, and thus to PAH, had a higher risk for genotoxicity compared to the control group. Since some of the detected PAH are potentially carcinogenic, PAH generated from operations on wood materials may be one of the causative agents for the observed increased genotoxicity in wood workers. Since increased genotoxicity is manifested in an increased MN frequency, the MN assay in nasal and buccal cells may become a relevant biomonitoring tool in the future for early detection of SNC risk.

Effects of Surface Properties and Wood Modification into Direct Printing on Wood

Building industry is a high volume branch which could provide prominent markets for wood based interior decoration solutions. Competition in interior decoration markets requires versatility in appearance. Versatility in wood appearance and added value could be achieved by printing grain patterns of different species or images directly onto wood. The problem when planning wood printing’s implementing into durable applications is basically how to transfer a high quality image or print sustainably onto wood, which is porous, heterogeneous, dimensionally unstable, non-white and rough. Wood preservation or treating, and modification can provide durability against degradation but also effect to the surface properties of wood which will effect on printability. Optimal adhesion is essential into print quality, as too high ink absorbance can cause spreading and too low ink absorbance cause pale prints. Different printing techniques have different requirements on materials and production. The direct printing on wood means, that intermedias are not used. Printing techniques with flexible printing plates or in fact non-impact techniques provide the best basis for wood printing. Inkjet printing of wood with different mechanical or chemical surface treatments, and wood plastic composite material gave good results that encourage further studies of the subject. Sanding the wood surface anti-parallel to the grain gave the best overall printing quality. Spreading parallel to the grain could not be avoided totally, except in cases where wood was treated hydrophobic so adhesion of the ink was not sufficient. Grain pattern of the underlying wood stays clearly visible in the printed images. Further studies should be made to fine tune the methods that already gave good results. Also effects of moisture content of wood, different inks, and long-term exposure to UV-radiation should be tested.

Hiontarobotti-solun tietojärjestelmä

Hiontarobotteja käytetään nopeuttamaan hiontaprosessia ja vähentämään henkilöiden tarvetta tehdä kuluttavaa ja raskasta työtä. Yleensä hiottavat kappaleet ovat suuria, jolloin hionta robotillakin kestää kauan. Kun hiottavat kappaleet ovat pieniä, robotti hioo kappaleen nopeasti. Tällöin tarvitaan automaattinen varastointi, jotta hiontarobotti pystyy jatkamaan nopeasti seuraavan kappaleen hiontaa. Automaattinen varastointi tarvitsee tiedonhallintajärjestelmän, jolla hallitaan varastossa olevien kappaleiden tietoja. Hiottava kappale täytyy esimerkiksi pystyä tunnistamaan ennen hionnan aloittamista. Yhtenä tunnistusmenetelmänä voidaan käyttää radiotaajuudella toimivia RFID-tunnisteita. Kun kappale tunnistetaan ennen hiontaa niin voidaan varmistua, että robotti suorittaa oikean hiontaohjelman kappaleelle. Diplomityö liittyy Master Automation Groupin ensimmäiseen automaattista varastoa hyödyntävään FlexMill™-hiontarobotti-soluun. Työssä on suunniteltu ja toteutettu tietokanta ja siihen liittyvä tietojärjestelmä. Kehitettävä ohjelma toimii solun toiminnasta vastaavan soluohjaimen tiedonhallintaosana. Ohjelma hyödyntää RFID-laitteita kappaleiden tunnistuksessa.

Katupölyn torjunta hiekoitushiekan poistossa kaupunkiympäristössä

Katupölyn torjumisessa hiekoitushiekan poistossa kaupunkiympäristössä tutkittiin, miten katujen talvikunnossapidon toimenpiteet ja talven hiekoitushiekkojen poistotyö vaikuttavat yhdyskuntailman hengitettävien hiukkasten PM10 -katupölyn määrään ja selvitettiin nykyiset käytännöt sekä uusia menetelmiä vähentää katupölyn määrää. Tutkimus on tehty Lappeenrannan kaupungin teknisen toimen katujen kunnossapidon tulosalueelle. Hankkeessa keskityttiin löytämään uusi ja tehokkaampi työmenetelmä sekä työjärjestys hiekanpoistoon, jotta työnaikaisen katupölyn määrä saataisiin minimoitua. Tehokkaita menetelmiä tutkimuksen perusteella olivat katujen ennalta kastelua ja työnaikainen pölynsidonta suolaliuoksella katupölyn vähentämiseen sekä oikean menetelmän käyttö. Pölynsidonta suolaliuoksella osoittautui tehokkaaksi akuutin katupölyn vähentämiskeinoksi. Pölynsidonta ei kuitenkaan poista katupölyä ja puhdistus tulee tehdä myöhemmin. Kadunvarren lumessa on suuria hiekoitushiekan kiintoainespitoisuuksia ja lumen poisviennillä voidaan saavuttaa hyötyjä katupölyongelman kannalta. Hiekoituspäivien lukumäärä on myös suoraan verrannollinen katupölyn määrään. Hiekoituksen ohella myös nastarenkaiden käyttö lisää katupölypäästöjä kaupunkialueilla. Nastarenkaiden vaikutusta katupölyn määrään ei selvitetty tässä tutkimuksessa tarkemmin, koska nastarenkaiden käyttökiellon voidaan olettaa lisäävän liikennetapaturmia sekä myös liukkaudentorjunnan tarvetta, eli hiekoitusta.

Avaliação da molhabilidade de soluções de tensoativos em aço inoxidável

With the increasing industrialization of the planet caused by globalization, it has become increasingly common to search for highly resistant and durable materials for many diverse branches of activities. Thus, production and demand for materials that meet these requirements have constantly increased with time. In view of this, stainless steel is presented as one of the materials which are suitable applications, due to many features that are interesting for several segments of the industry. Concerns of oil companies over heavy oil reservoirs have grown steadily for the last decades. Rheological properties of these oils impair their transport in conventional flow systems. This problem has created the need to develop technologies to improve flow and transport, reducing operation costs so as to enable oil production in the reservoir. Therefore, surfactant-based chemical systems are proposed to optimize transport conditions, effected by reduction of interfacial tensions, thereby enhancing the flow of oil in ducts and reducing load losses by friction. In order to examine such interactions, a study on the wettability of metallic surfaces has been undertaken, represented by measuring of contact angle of surfactant solutions onto flat plates of 304 stainless steel. Aqueous solutions of KCl, surfactants and mixtures of surfactants, with linear and aromatic hydrocarbon chain and ethoxylation degrees ranging between 20 to 100, have been tested. The wettability was assessed by means of a DSA 100 krüss goniometer. The influence of roughness on the wettability was also investigated by machining and polished the stainless steel plates with sandpapers of references ranging between 100 of 1200. The results showed that sanding and polishing plates result in decrease of wettability. As for the solutions, they have provided better wettability of the stainless steel than the KCl solutions tested. It was also been concluded that surfactant mixtures is an option to be considered, since they promote interactions that generate satisfactory contact angles for a good wettability on the stainless steel plate. Another conclusion refers to the influence of the ethoxylation degree of the nonionic surfactant molecules on wettability. It has been observed that contact angles decrease with decreasing ethoxylation degrees. This leads us to conclude that molecules with higher ethoxylation degree, being more hydrophobic, decrease the interaction of water with the ducts, thereby reducing friction and improving the flow

Evolução morfodinâmica da região de influência estuarina do Rio Curimataú/RN, com ênfase nas alternativas do ambiente deposicional de manguezal e a integração de geodados em Sig

The estuaries are important investigation zones of the actual morphodynamic and of depositional facies of recent geological history. They are constituted in important receptor means of the coastal area sediments, where the evolutionary processes occur quickly. They are also attractive means for the development of anthropic activities, which in a disordered way interfere in the active processes in the sedimentary balance of the coastal areas. Among the human interventions, the alterations of the depositional environment of mangroves in areas of tropical estuary is deserving relevance, whose implications for the environment estuarine and the coastal adjacent, they are still far to be known. Due to the interest of the sedimentologic component in the comprehension of the processes linked to the evolution of the environments estuarine and coastal adjacent, this work, aimed at the understanding of the morphodynamic coastal phenomena that comprise the region of estuarine influence of the River Curimataú / RN. It was also evaluated in the morphodynamic context the implications due to alterations of the depositional environment of mangrove by anthropic activity. The Curimataú Estuary, located in the south portion of the oriental coast of Rio Grande do Norte, in the last decades has been objective of the overwhelming occupation of the shrimp farm in areas of mangroves, which were implanted with perspectives of development in a short to medium period. On the other hand, the estuary and its region of coastal influence lacks enough information to subsidize the planning and reorganization more effective of the surrounding activities. Thus, it was intended with this work to give a contribution target tothe maintainable use of the coastal resources of this region. A series of studies using data of orbital and acoustic remote sensing, as of sediments sampling, were executed in the gutter of the estuary. The obtained results starting from the interpretation of bathymetric maps, echo sounder graphics and of distribution of sediments made possible the location of the estuary based in morpho-sedimentar criteria. The estuarine tidal flat was dissected in environments of intertidal mangroves, supratidal mangroves and apicuns with base in the integration of data of sensor optic and of radar following by the field control. The adjacent coast that is influenced by the Curimataú estuary, was segmented according to their geomorphologic characteristics, where each segment had a point of observation of the beach morphodynamic, during the period from january/2001 to february/2002. Once every month, beaches profiles, collections of sediments in the beach zones, as measurement of hydrodynamic parameters were executed. The results of the observations of the tidal environment showed that the area of estuarine influence of the Curimataú begins to suffer negative sedimentary taxes, where in some beaches, the erosive processes are already observed. The granulometric characteristics of the beach sediments start to tend for the increase of thin sand in the erosive periods. The destruction of the depositional environments of mangroves of the Curimataú estuary, to the construction of shrimp farms, can be providing the diminution of the tidal prism of the estuary, enlarging the effects of the local increasing of the sea level, through the smaller supplying of sediments to the adjacent coast. Besides this, it was verified the possibility of the sanding of the tidal channel in the margins of the destroyed areas of mangroves, where very high taxes of sedimentation of thin materials were estimated in case of these areas were preserve

Controle de erosão em estradas rurais não pavimentadas, utilizando sistema de terraceamento com gradiente associado a bacias de captação

The agricultural unpaved roads are important road structures for the economic and social agricultural development of the Nation, and the erosion provoked by rain water in the road bed and sides are closely related to bad draining, one of the main factors for their degradation. In order to make the draining system adequate, it is necessary to know about erodibility, infiltration capacity of water in the ground and adoption of mechanical slope abatement with grid elevation and water interception. This study presents drainage model through the construction of terraces with gradient transversally associated to the capitation basin in abruptic red dystrophic argisol soils, medium sandy texture, based on slops abatement techniques, elevating the road bed and deviating flow. The grain sized fractions of this ground (sand, silt, clay) and the aggregate stability indicated that this ground, under anthropic action, presents erosive processes resulting in superficial draining with ground hauling, sanding sources and courses of water situation below roads, providing great environmental impacts in the hydric bodies. The reduction of erosion problems in these unpaved roads is in the adoption of measures that intercept waters from the draining of their stream bed itself, as well as pluvial waters comings from adjacent areas of contribution, that are collected and conducted to inlaid terraces and capitation basis.

Superação de dormência e influência dos fatores ambientais na germinação de sementes de Spermacoce latifolia

Understanding basic information on weed biology contributes to the implementation of appropriate management and control strategies. Thus, this work was developed to evaluate the germination of Spermacoce latifolia Aubl. seeds, an important weed in reforestation areas. The seeds were subjected to dormancy break treatments, in which the mechanical scarification, chemical treatment (H2SO 4 and KNO 3), heat treatment, and control, were evaluated. Three more tests were done determinate the effects of temperature (10, 15, 20, 25, 30 and 35°C), light filters (absence of light and red, green, yellow, distant red, blue, orange and clear light) and water availability (0.0, -0.2, -0.4, -0.6, -0.8 and -1.0 MPa) on the seeds germination and vigor. The treatments were arranged in a completely randomized design with four replications, and the experimental plot was constituted by gerbox plastic boxes with 50 seeds. The mechanical scarification (sanding) provided the best dormancy break, indicating that Spermacoce latifolia seeds have tegument water impermeability. The seeds showed higher germination percentage under conditions of mild water stress (-0.2 MPa) and the optimal temperature was 25°C. The blue light reduced seed germination.