Paperin ominaisuuksien yhteys rullavanan esiintymiseen

Tämän työn tavoitteena oli pyrkiä selvittämään, mitkä valmiin paperin ominaisuudet ovat rullavanan kannalta merkittäviä ja millä menetelmillä niitä voitaisiin mitata kvantitatiivisesti, jotta niistä johtuvat rullausviat voitaisiin selittää ja välttää. Tarkoituksena oli vahvistaa ja lisätä tietämystä rullaustapahtumasta ja edistää erilaisten profiilien hallintaa ja käyttöä vanaisuuden ja rullarakenteen kannalta. Kirjallisuusosassa selvitettiin rullaustapahtumaa sekä rullan rakennetta ja siihen vaikuttavia paperin ominaisuuksia yleisesti. Tässä yhteydessä paneuduttiin rullavanan syntymekanismeihin ja sen synnyn mahdollisiin ehkäisymenetelmiin. Lisäksi käsiteltiin paperifysikaalisesta näkökulmasta tärkeimpien paperin rakenne- ja ominaisuusprofiilien yhteyttä rullavanaan sekä paksuusvanan käyttäytymistä nipissä ja eri rullausvaiheissa. Kirjallisuusosan pohjalta päädyttiin valitsemaan tietyt menetelmät analyysien tekoon siten, että tärkeimmät paperin ja konerullan rakennetta tai ominaisuutta kuvaavat osa-alueet voitiin kattaa. Luonnehdinta tehtiin tarkastelemalla sekä rakenne-, ominaisuus- että tilasuureita. Saatujen tulosten mukaan rullavanan ehkäisyn kannalta SC-paperissa on olennaista kuivaneliömassan, paksuuden, kosteuden ja kireyden piikikkyyden sekä rajujen paikallisten profiilimuutosten vähentäminen. Näiden ja muiden mitattujen ominaisuuksien perusteella konerullan halkaisijavaihtelut johtuivat pääosin paperissa olevasta paikallisesta tiheyspoikkeamasta tai suuremmasta neliömassasta. Nämä ilmenivät paperissa joko paksumpina tai vähemmän kokoonpuristuvina kohtina. Kalanteroinnin seurauksena nämä kohdat muuttuivat useimmiten kireydeltään huomattavasti löysemmiksi alueiksi ja niiden haitallisuutta lisäsi normaalia kireämmän kohdan sijainti löysän kohdan välittömässä läheisyydessä. Käytetyistä laboratoriomittausmenetelmistä parhaiten rullavanan kvantitatiiviseen analysointiin soveltui Tapio-analysaattori. Kokoonpuristumisessa KCL-PURRE -mittalaitteella ei pystytty havaitsemaan merkittäviä eroja poikkisuunnan eri kohtien välillä, mutta syklisessä puristuksessa havaittiin pattikohdan suhteellisen palautuvan paksuuden olevan merkittävästi referenssikohtia suurempi. Prosessin tilaa mittaavista menetelmistä luotettavimmaksi analyysityökaluksi osoittautui PAROtester2 -kovuusmittauslaite. Lisäksi IQTension[TM] -kireysmittauspalkilla pystyttiin saamaan erittäin selvästi esille paikalliset kireyserot, joita ilmenee rullavanojen yhteydessä. Rullavanan havaitsemisen kannalta olisi oleellista tarkastella profiilin muotoparametrien muutoksia. Tämä voisi käytännössä tarkoittaa uusien tunnuslukujen tai esitystapojen käyttöönottoa. Eräs havainnollinen profiilin luonnetta kuvaava ominaisuus olisi jyrkkyysprofiilin piirtäminen tärkeimmistä ominaisuuksista. Lisäksi rullavanoja koskien eräs mittausteknisesti merkittävä tekijä on karheuden vaikutuksen eliminointi paksuusmittauksessa. Rullalla olevan paperin paksuutta tulisi mitata riittävän paksun pinon avulla ja mieluummin sillä paineella, joka vaikuttaa rullassa. Työssä havaittiin, että rullavanan kvantitatiivinen analysointi on mahdollista olemassa olevilla menetelmillä. Mittausmenetelmien tarkka tunteminen ja eri suureiden samanaikainen tarkastelu on tällöin oleellista

The Radiation, snow characteristics and albedo at summit (RASCALS) expedition report

The RASCALS expedition spent over three weeks at the Summit camp research station near the top of the Greenland Ice Sheet during polar summer 2010. During this time, detailed measurements of the physical and optical properties of Arctic perennial snow were carried out concurrently with snow albedo and reflectance measurements. Favorable weather conditions during the campaign enabled the collection of a large dataset on Arctic snow albedo and associated quantities for use in developing and validating remote sensing algorithms for snow albedo using satellites. This report provides a description of the measurements and conditions during the campaign.RASCALS-retkikunnan tehtävä oli tutkia Grönlannin mannerjäätikön lumen fysikaalisia ja optisia ominaisuuksia sekä Auringon valon vuorovaikutusta lumen kanssa. Retikunta vietti hieman yli kolme viikkoa mannerjäätikön keskellä sijaitsevalla Summit Camp-tutkimusasemalla tehden mittauksia. Sääolot suosivat kampanjaa, jonka seurauksena onnistuttiin keräämään laaja ja monipuolinen tietoaineisto mannerjäätikön lumen pintakerroksesta ja eritoten lumen heijastavuuden (albedon)käyttäytymisestä. Aineisto on hyödyllinen kehitettäessä ja varmennettaessa lumen albedon kaukokartoitusmenetelmiä satelliiteilla

Postikortteja Corona Ground Zerosta Helsinkiin : Huomioita pandemiasta ja ympäristökriisistä

Non peer reviewe

Modeling of Dead Wood Potential Based on Tree Stand Data

Here we present a framework for identifying areas with high dead wood potential (DWP) for conservation planning needs. The amount and quality of dead wood and dying trees are some of the most important factors for biodiversity in forests. As they are easy to recognize on site, it is widely used as a surrogate marker for ecological quality of forests. However, wall-to-wall information on dead wood is rarely available on a large scale as field data collection is expensive and local dead wood conditions change rapidly. Our method is based on the forest growth models in the Motti forest simulator, taking into account 168 combinations of tree species, site types, and vegetation zones as well as recommendations on forest management. Simulated estimates of stand-level dead wood volume and mean diameter at breast height were converted into DWP functions. The accuracy of the method was validated on two sites in southern and northeastern Finland, both consisting of managed and conserved boreal forests. Altogether, 203 field plots were measured for living and dead trees. Data on living trees were inserted into corresponding DWP functions and the resulting DWPs were compared to the measured dead wood volumes. Our results show that DWP modeling is an operable tool, yet the accuracy differs between areas. The DWP performs best in near-pristine southern forests known for their exceptionally good quality areas. In northeastern areas with a history of softer management, the differences between near-pristine and managed forests is not as clear. While accurate wall-to-wall dead wood inventory is not available, we recommend using DWP method together with other spatial datasets when assessing biodiversity values of forests

Systematic investigation of the adsorption potential of lignin- and cellulose-based nanomaterials towards pharmaceuticals

Pharmaceuticals are emerging water pollutants that pose a global threat to the sustainability and safety of aquatic resources. To mitigate their potential hazardous impacts, one of the keys is to address the removal of pharmaceutical residues from wastewaters. In this study, adsorption utilizing nanostructured wood-based adsorbents is viewed as a simple and versatile wastewater treatment method that can be adapted to remove pharmaceutical pollutants. To realize this potential, there is a need to understand the interaction of wood-based nanomaterials towards various types of pharmaceuticals. Thus, this study characterized and investigated the adsorption potential of the two common wood-based nanomaterials, the nanocelluloses and lignin nanoparticles (LNPs), towards various types of pharmaceuticals. The unmodified and cationized LNPs from hardwood and softwood lignin and nanocelluloses (TEMPO-oxidized cellulose nanofibrils (TCNF), cellulose and lignocellulose nanofibrils) were characterized for their morphology, zeta potential and surface charge density at different pHs. The adsorption capacity was determined from a multi-analyte adsorption system consisting of seven pharmaceuticals with different chemical characteristics (aromatic, non-aromatic, anionic, cationic, and neutral). Overall, the LNPs, with their polyaromatic structure, adsorbed a wider range of pharmaceuticals than the nanocelluloses. Among the nanocelluloses, the TCNF exhibited the highest adsorption capacity for cationic pharmaceuticals. Based on these findings, LNPs and TCNF are promising materials that can be combined to construct novel nanostructured adsorbents for pharmaceutical pollutants in water. The interaction of different pharmaceuticals with LNPs and nanocelluloses as revealed in this study can also be beneficial in other applications, such as drug encapsulation and release.Peer reviewe

Nanocellulose aerogel membranes for optimal electrolyte filling in dye solar cells

A new method for depositing electrolyte in dye solar cells (DSCs) is introduced: a nanocellulose hydrogel membrane is screen printed on the counter electrode and further freeze-dried to form a highly porous nanocellulose aerogel, which acts as an absorbing sponge for the liquid electrolyte. When the nanoporous dye-sensitized TiO2 photoelectrode film is pressed against the wetted aerogel, it becomes filled with the electrolyte. The electrolyte flows inside the TiO2 film only about ten micrometers (i.e. the TiO2 film thickness) whereas in the conventional filling method, where the electrolyte is pumped through the cell, it flows about 1000-times longer distance, which is known to cause uneven distribution of the electrolyte components due to a molecular filtering effect. Furthermore, with the new method there is no need for electrolyte filling holes which simplifies significantly the sealing of the cells and eliminates one common pathway for leakage. Photovoltaic analysis showed that addition of the nanocellulose aerogel membrane did not have a statistically significant effect on cell efficiency, diffusion in the electrolyte or charge transfer at the counter electrode. There was, however, a clear difference in the short circuit current density and open circuit voltage between the cells filled with the aerogel method and in the reference cells filled with the conventional method, which appeared to be caused by the differences in the electrolyte filling instead of the nanocellulose itself. Moreover, accelerated aging tests at 1 Sun 40 °C for 1000 h showed that the nanocellulose cells were as stable as the conventional DSCs. The nanocellulose aerogel membranes thus appear inert with respect to both performance and stability of the cells, which is an important criterion for any electrolyte solidifying filler material.Peer reviewe

Lignin nanoparticle-decorated nanocellulose cryogels as adsorbents for pharmaceutical pollutants

Adsorption is a relatively simple wastewater treatment method that has the potential to mitigate the impacts of pharmaceutical pollution. This requires the development of reusable adsorbents that can simultaneously remove pharmaceuticals of varying chemical structure and properties. Here, the adsorption potential of nanostructured wood-based adsorbents towards different pharmaceuticals in a multi-component system was investigated. The adsorbents in the form of macroporous cryogels were prepared by anchoring lignin nanoparticles (LNPs) to the nanocellulose network via electrostatic attraction. The naturally anionic LNPs were anchored to cationic cellulose nanofibrils (cCNF) and the cationic LNPs (cLNPs) were combined with anionic TEMPO-oxidized CNF (TCNF), producing two sets of nanocellulose-based cryogels that also differed in their overall surface charge density. The cryogels, prepared by freeze-drying, showed layered cellulosic sheets randomly decorated with spherical lignin on the surface. They exhibited varying selectivity and efficiency in removing pharmaceuticals with differing aromaticity, polarity and ionic characters. Their adsorption potential was also affected by the type (unmodified or cationic), amount and morphology of the lignin nanomaterials, as well as the pH of the pharmaceutical solution. Overall, the findings revealed that LNPs or cLNPs can act as functionalizing and crosslinking agents to nanocellulose-based cryogels. Despite the decrease in the overall positive surface charge, the addition of LNPs to the cCNF-based cryogels showed enhanced adsorption, not only towards the anionic aromatic pharmaceutical diclofenac but also towards the aromatic cationic metoprolol (MPL) and tramadol (TRA) and neutral aromatic carbamazepine. The addition of cLNPs to TCNF-based cryogels improved the adsorption of MPL and TRA despite the decrease in the net negative surface charge. The improved adsorption was attributed to modes of removal other than electrostatic attraction, and they could be 7C-7C aromatic ring or hydrophobic interactions brought by the addition of LNPs or cLNPs. However, significant improvement was only found if the ratio of LNPs or cLNPs to nanocellulose was 0.6:1 or higher and with spherical lignin nanomaterials. As crosslinking agents, the LNPs or cLNPs affected the rheological behavior of the gels, and increased the firmness and decreased the water holding capacity of the corresponding cryogels. The resistance of the cryogels towards disintegration with exposure to water also improved with crosslinking, which eventually enabled the cryogels, especially the TCNF-based one, to be regenerated and reused for five cycles of adsorption-desorption experiment for the model pharmaceutical MPL. Thus, this study opened new opportunities to utilize LNPs in providing nanocellulose-based adsorbents with additional functional groups, which were otherwise often achieved by rigorous chemical modifications, at the same time, crosslinking the nanocellulose network.Peer reviewe