Flow phenomena, heat and mass transfer in microchannel reactors

The studies of flow phenomena, heat and mass transfer in microchannel reactors are beneficial to estimate and evaluate the ability of microchannel reactors to be operated for a given process reaction such as Fischer-Tropsch synthesis. The flow phenomena, for example, the flow regimes and flow patterns in microchannel reactors for both single phase and multiphase flow are affected by the configuration of the flow channel. The reviews of the previous works about the analysis of related parameters that affect the flow phenomena are shown in this report. In order to predict the phenomena of Fischer-Tropsch synthesis in microchannel reactors, the 3-dimensional computational fluid dynamic simulation with commercial software package FLUENT was done to study the flow phenomena and heat transfer for gas phase Fischer-Tropsch products flow in rectangular microchannel with hydraulic diameter 500 ¿m and length 15 cm. Numerical solution with slip boundary condition was used in the simulation and the flowphenomena and heat transfer were determined.

Typpeä sisältävien jätevesien käsittely 2-n-PRO menetelmällä

Työssä tutkittiin kaksivaiheisen typenpoistoprosessin (2-N-PRO) soveltuvuutta Joutsenon Kukkuroinmäen aluejätekeskuksen kompostointilaitoksen jätevesille pilot-kokein 12.1.- 5.4.2006. Kompostilaitoksella on jätevesien esikäsittelytarve korkeista ammoniumtyppipitoisuuksista johtuen. Pilot-laitteisto koostuu sekoitussäiliöstä, strippaustornista ja katalyyttipolttimesta. Käsiteltävän jäteveden pH nostetaan korkealle tasolle, jolloin ammoniumtyppi muuttuu ammoniakiksi. Vesi johdetaan strippaustorniin, jossa se sadetetaan tornin pohjalle. Ammoniakki erottuu sadetuksessa ilmaan, joka imetään katalyyttipolttimelle. Katalyyttinen poltin käsittelee ammoniakkia typpikaasuksi. Pilot-kokeet suoritettiin jatkuvatoimisesti. Laitteisto pystyy erottamaan jätevedestä ammoniumtyppeä ammoniakiksi ja käsittelemään ammoniakin pääosin typpikaasuksi. Lisäksi suoritettiin panoskoe, jonka tulokset tukevat jatkuvatoimisesta käytöstä saatuja tuloksia.

Verification of a dynamic laboratory scale former

Laboratoriomittakaavainen formeri on välttämätön, jotta paperinvalmistusprosessin jäljitteleminen olisi mahdollista. Vaikka erilaisia formereita löytyykin paperiteollisuudesta, tilaa on kuitenkin laboratoriomittakaavaiselle paperinvalmistusmenetelmälle, joka sijoittuisipilottikoneen ja perinteisen laboratorioarkkimuotin välille. Formeri, jolla saadaan aikaiseksi oikean paperinvalmistuksen kaltaiset olosuhteet ja ilmiöt on kehitetty, ja sen toiminta on testattu Nalcon Papermaking Centreof Excellence:ssä Espoossa. Formeri on yhdistetty Nalcon lähestymisjärjetelmäsimulaattoriin ja simulaattorilla aikaansaadut hydro-kemialliset ilmiöt voidaan testata nyt myös arkeista. Laitteessa on perälaatikko ja viiraosa. Perälaatikosta massa virtaa viiralle, joka liikkuu eteenpäin hihnakuljettimen hihnojen päällä. Suihku-viira -suhdetta voidaan muuttaa joko muuttamalla virtausnopeutta tai viiran nopeutta tai säätämällä perälaatikon huuliaukkoa. Formerintoiminnan testaus osoitti, että se toimii teknisesti hyvin ja tulokset ovat toistettavia ja loogisia. Arkeissa kuidut ovat orientoituneet, formaatio ja vetolujuussuhde KS/PS riippuvat voimakkaasti suihku-viira -suhteesta, kuten oikeillakinpaperikoneilla.

Sediment budget monitoring of debris-flow and bedload transport in the Manival Torrent, SE France

Steep mountain catchments typically experience large sediment pulses from hillslopes which are stored in headwater channels and remobilized by debris-flows or bedload transport. Event-based sediment budget monitoring in the active Manival debris-flow torrent in the French Alps during a two-year period gave insights into the catchment-scale sediment routing during moderate rainfall intensities which occur several times each year. The monitoring was based on intensive topographic resurveys of low- and high-order channels using different techniques (cross-section surveys with total station and high-resolution channel surveys with terrestrial and airborne laser scanning). Data on sediment output volumes from the main channel were obtained by a sediment trap. Two debris-flows were observed, as well as several bedload transport flow events. Sediment budget analysis of the two debris-flows revealed that most of the debris-flow volumes were supplied by channel scouring (more than 92%). Bedload transport during autumn contributed to the sediment recharge of high-order channels by the deposition of large gravel wedges. This process is recognized as being fundamental for debris-flow occurrence during the subsequent spring and summer. A time shift of scour-and-fill sequences was observed between low- and high-order channels, revealing the discontinuous sediment transfer in the catchment during common flow events. A conceptual model of sediment routing for different event magnitude is proposed.

Development of fluid conduits in the auriferous shear zones of the Hutti Gold Mine, India: evidence for spatially and temporally heterogeneous fluid flow

The gold mineralization of the Hutti Mine is hosted by nine parallel, N - S trending, steeply dipping, 2 - 10 m wide shear zones, that transect Archaean amphibolites. The shear zones were formed after peak metamorphism during retrograde ductile D, shearing in the lower amphibolite facies. They were reactivated in the lower to mid greenschist facies by brittle-ductile D-3 shearing and intense quartz veining. The development of a S-2-S-3 crenulation cleavage facilitates the discrimination between the two deformation events and contemporaneous alteration and gold mineralization. Ductile D, shearing is associated with a pervasively developed distal chlorite - sed cite alteration assemblage in the outer parts of the shear zones and the proximal biotite-plagioclase alteration in the center of the shear zones. D3 is characterized by development of the inner chlorite-K-feldspar alteration, which forms a centimeter-scale alteration halo surrounding the laminated quartz veins and replaces earlier biotite along S-3. The average size of the laminated vein systems is 30-50 m along strike as well as down-dip and 2-6 m in width. Mass balance calculations suggest strong metasomatic changes for the proximal biotite-plagioclase alteration yielding mass and volume increase of ca. 16% and 12%, respectively. The calculated mass and volume changes of the distal chlorite-sericite alteration (ca. 11%, ca. 8%) are lower. The decrease in 6180 values of the whole rock from around 7.5 parts per thousand for the host rocks to 6-7 parts per thousand for the distal chlorite-sericite and the proximal biotite-plagioclase alteration and around 5 parts per thousand for the inner chlorite-K-feldspar alteration suggests hydrothermal alteration during two-stage deformation and fluid flow. The ductile D-2 deformation in the lower amphibolite facies has provided grain scale porosities by microfracturing. The pervasive, steady-state fluid flow resulted in a disseminated style of gold-sulfide mineralization and a penetrative alteration of the host rocks. Alternating ductile and brittle D3 deformation during lower to mid greenschist facies conditions followed the fault-valve process. Ductile creep in the shear zones resulted in a low permeability environment leading to fluid pressure build-up. Strongly episodic fluid advection and mass transfer was controlled by repeated seismic fracturing during the formation of laminated quartz(-gold) veins. The limitation of quartz veins to the extent of earlier shear zones indicate the importance of preexisting anisotropies for fault-valve action and economic gold mineralization. (C) 2003 Elsevier B.V. All rights reserved.

Value added logistics in supply and demand chain. Smile. Part 2. eBusiness in a service business. Case: A maintenance and operations network in forest industry

VVALOSADE is a research project of professor Anita Lukka's VALORE research team in the Lappeenranta University of Technology. The VALOSADE includes the ELO technology program of Tekes. SMILE is one of four subprojects of the VALOSADE. The SMILE study focuses on the case of the company network that is composed of small and micro-sized mechanical maintenance service providers and forest industry as large-scale customers. The basic principle of the SMILE study is the communication and ebusiness in supply and demand networks. The aim of the study is to develop ebusiness strategy, ebusiness model and e-processes among the SME local service providers, and onthe other hand, between the local service provider network and the forest industry customers in a maintenance and operations service business. A literature review, interviews and benchmarking are used as research methods in this qualitative case study. The first SMILE report, 'Ebusiness between Global Company and Its Local SME Supplier Network', concentrated on creating background for the SMILE study by studying general trends of ebusiness in supply chains and networks of different industries. This second phase of the study concentrates on case network background, such as business relationships, information systems and business objectives; core processes in maintenance and operations service network; development needs in communication among the network participants; and ICT solutions to respond needs in changing environment. In the theory part of the report, different ebusiness models and frameworks are introduced. Those models and frameworks are compared to empirical case data. From that analysis of the empirical data, therecommendations for the development of the network information system are derived. In process industry such as the forest industry, it is crucial to achieve a high level of operational efficiency and reliability, which sets up great requirements for maintenance and operations. Therefore, partnerships or strategic alliances are needed between the network participants. In partnerships and alliances, deep communication is important, and therefore the information systems in the network also are critical. Communication, coordination and collaboration will increase in the case network in the future, because network resources must be optimised to improve competitive capability of the forest industry customers and theefficiency of their service providers. At present, ebusiness systems are not usual in this maintenance network. A network information system among the forest industry customers and their local service providers actually is the only genuinenetwork information system in this total network. However, the utilisation of that system has been quite insignificant. The current system does not add value enough either to the customers or to the local service providers. At present, thenetwork information system is the infomediary that share static information forthe network partners. The network information system should be the transaction intermediary, which integrates internal processes of the network companies; the network information system, which provides common standardised processes for thelocal service providers; and the infomediary, which share static and dynamic information on right time, on right partner, on right costs, on right format and on right quality. This study provides recommendations how to develop this system in the future to add value to the network companies. Ebusiness scenarios, vision, objectives, strategies, application architecture, ebusiness model, core processes and development strategy must be considered when the network information system will be developed in the next development step. The core processes in the case network are demand/capacity management, customer/supplier relationship management, service delivery management, knowledge management and cash flow management. Most benefits from ebusiness solutions come from the electrifying of operational level processes, such as service delivery management and cash flow management.

Theoretical Analysis and Simulations of Vertically Vibrated Granular Materials

The dynamical properties ofshaken granular materials are important in many industrial applications where the shaking is used to mix, segregate and transport them. In this work asystematic, large scale simulation study has been performed to investigate the rheology of dense granular media, in the presence of gas, in a three dimensional vertical cylinder filled with glass balls. The base wall of the cylinder is subjected to sinusoidal oscillation in the vertical direction. The viscoelastic behavior of glass balls during a collision, have been studied experimentally using a modified Newton's Cradle device. By analyzing the results of the measurements, using numerical model based on finite element method, the viscous damping coefficient was determinedfor the glass balls. To obtain detailed information about the interparticle interactions in a shaker, a simplified model for collision between particles of a granular material was proposed. In order to simulate the flow of surrounding gas, a formulation of the equations for fluid flow in a porous medium including particle forces was proposed. These equations are solved with Large Eddy Simulation (LES) technique using a subgrid-model originally proposed for compressible turbulent flows. For a pentagonal prism-shaped container under vertical vibrations, the results show that oscillon type structures were formed. Oscillons are highly localized particle-like excitations of the granular layer. This self-sustaining state was named by analogy with its closest large-scale analogy, the soliton, which was first documented by J.S. Russell in 1834. The results which has been reportedbyBordbar and Zamankhan(2005b)also show that slightly revised fluctuation-dissipation theorem might apply to shaken sand, which appears to be asystem far from equilibrium and could exhibit strong spatial and temporal variations in quantities such as density and local particle velocity. In this light, hydrodynamic type continuum equations were presented for describing the deformation and flow of dense gas-particle mixtures. The constitutive equation used for the stress tensor provides an effective viscosity with a liquid-like character at low shear rates and a gaseous-like behavior at high shear rates. The numerical solutions were obtained for the aforementioned hydrodynamic equations for predicting the flow dynamics ofdense mixture of gas and particles in vertical cylindrical containers. For a heptagonal prism shaped container under vertical vibrations, the model results were found to predict bubbling behavior analogous to those observed experimentally. This bubbling behavior may be explained by the unusual gas pressure distribution found in the bed. In addition, oscillon type structures were found to be formed using a vertically vibrated, pentagonal prism shaped container in agreement with computer simulation results. These observations suggest that the pressure distribution plays a key rolein deformation and flow of dense mixtures of gas and particles under vertical vibrations. The present models provide greater insight toward the explanation of poorly understood hydrodynamic phenomena in the field of granular flows and dense gas-particle mixtures. The models can be generalized to investigate the granular material-container wall interactions which would be an issue of high interests in the industrial applications. By following this approach ideal processing conditions and powder transport can be created in industrial systems.

Impacts of upland open drains upon runoff generation: a numerical assessment of catchment-scale impacts

Shallow upland drains, grips, have been hypothesized as responsible for increased downstream flow magnitudes. Observations provide counterfactual evidence, often relating to the difficulty of inferring conclusions from statistical correlation and paired catchment comparisons, and the complexity of designing field experiments to test grip impacts at the catchment scale. Drainage should provide drier antecedent moisture conditions, providing more storage at the start of an event; however, grips have higher flow velocities than overland flow, thus potentially delivering flow more rapidly to the drainage network. We develop and apply a model for assessing the impacts of grips on flow hydrographs. The model was calibrated on the gripped case, and then the gripped case was compared with the intact case by removing all grips. This comparison showed that even given parameter uncertainty, the intact case had significantly higher flood peaks and lower baseflows, mirroring field observations of the hydrological response of intact peat. The simulations suggest that this is because delivery effects may not translate into catchment-scale impacts for three reasons. First, in our case, the proportions of flow path lengths that were hillslope were not changed significantly by gripping. Second, the structure of the grip network as compared with the structure of the drainage basin mitigated against grip-related increases in the concentration of runoff in the drainage network, although it did marginally reduce the mean timing of that concentration at the catchment outlet. Third, the effect of the latter upon downstream flow magnitudes can only be assessed by reference to the peak timing of other tributary basins, emphasizing that drain effects are both relative and scale dependent. However, given the importance of hillslope flow paths, we show that if upland drainage causes significant changes in surface roughness on hillslopes, then critical and important feedbacks may impact upon the speed of hydrological response. Copyright (c) 2012 John Wiley & Sons, Ltd.

Flow resistance equations for mountain rivers

Three models of flow resistance (a Keulegan-type logarithmic law and two models developed for large-scale roughness conditions: the full logarithmic law and a model based on an inflectional velocity profile) were calibrated, validated and compared using an extensive database (N = 1,533) from rivers and flumes, representative of a wide hydraulic and geomorphologic range in the field of gravel-bed and mountain channels. It is preferable to apply the model based on an inflectional velocity profile in the relative submergence (y/d90) interval between 0.5 and 15, while the full logarithmic law is preferable for values below 0.5. For high relative submergence, above 15, either the logarithmic law or the full logarithmic law can be applied. The models fitted to the coarser percentiles are preferable to those fitted to the median diameter, owing to the higher explanatory power achieved by setting a model, the smaller difference in the goodness-of-fit between the different models and the lower influence of the origin of the data (river or flume).

Use of the heat dissipation method for sap flow measurement in citrus nursery trees1

Sap flow could be used as physiological parameter to assist irrigation of screen house citrus nursery trees by continuous water consumption estimation. Herein we report a first set of results indicating the potential use of the heat dissipation method for sap flow measurement in containerized citrus nursery trees. 'Valencia' sweet orange [Citrus sinensis (L.) Osbeck] budded on 'Rangpur' lime (Citrus limonia Osbeck) was evaluated for 30 days during summer. Heat dissipation probes and thermocouple sensors were constructed with low-cost and easily available materials in order to improve accessibility of the method. Sap flow showed high correlation to air temperature inside the screen house. However, errors due to natural thermal gradient and plant tissue injuries affected measurement precision. Transpiration estimated by sap flow measurement was four times higher than gravimetric measurement. Improved micro-probes, adequate method calibration, and non-toxic insulating materials should be further investigated.

Use of the dried blood spot sampling process coupled with fast gas chromatography and negative-ion chemical ionization tandem mass spectrometry: application to fluoxetine, norfluoxetine, reboxetine, and paroxetine analysis.

The objective of this work was to combine the advantages of the dried blood spot (DBS) sampling process with the highly sensitive and selective negative-ion chemical ionization tandem mass spectrometry (NICI-MS-MS) to analyze for recent antidepressants including fluoxetine, norfluoxetine, reboxetine, and paroxetine from micro whole blood samples (i.e., 10 microL). Before analysis, DBS samples were punched out, and antidepressants were simultaneously extracted and derivatized in a single step by use of pentafluoropropionic acid anhydride and 0.02% triethylamine in butyl chloride for 30 min at 60 degrees C under ultrasonication. Derivatives were then separated on a gas chromatograph coupled with a triple-quadrupole mass spectrometer operating in negative selected reaction monitoring mode for a total run time of 5 min. To establish the validity of the method, trueness, precision, and selectivity were determined on the basis of the guidelines of the "Société Française des Sciences et des Techniques Pharmaceutiques" (SFSTP). The assay was found to be linear in the concentration ranges 1 to 500 ng mL(-1) for fluoxetine and norfluoxetine and 20 to 500 ng mL(-1) for reboxetine and paroxetine. Despite the small sampling volume, the limit of detection was estimated at 20 pg mL(-1) for all the analytes. The stability of DBS was also evaluated at -20 degrees C, 4 degrees C, 25 degrees C, and 40 degrees C for up to 30 days. Furthermore, the method was successfully applied to a pharmacokinetic investigation performed on a healthy volunteer after oral administration of a single 40-mg dose of fluoxetine. Thus, this validated DBS method combines an extractive-derivative single step with a fast and sensitive GC-NICI-MS-MS technique. Using microliter blood samples, this procedure offers a patient-friendly tool in many biomedical fields such as checking treatment adherence, therapeutic drug monitoring, toxicological analyses, or pharmacokinetic studies.

Sähköä ja lämpöä tuottavien maakaasukäyttöisten pienvoimalaitosten kannattavuus Turengissa

Diplomityössä tutkitaan sähkön ja lämmön yhteistuotannon kannattavuutta Turengin nykyisen lämmöntuotannon yhteydessä. Tavoitteena on löytää taloudellisesti kilpailukykyiset tuotantovaihtoehdot Turengin energiahuollon kehittämisessä. Ensimmäisenä tarkasteltarkastellaan voimalaitoksen nykyiseen tuotantolaitteistoon kuuluvan vastapainehöyryturbiinin käyttöönoton mahdollisuuksia. Tämän jälkeen suoritetaan kannattavuuslaskelmat neljälle vaihtoehtoiselle investointitapaukselle. Voimalaitosinvestoinnit kohdistuvat kaasumoottori- ja kaasuturbiinivoimalaitoksiin, joilla tuotetaan sähköä, kaukolämpöä ja eräissä tapauksissa myös prosessihöyryä. Voimalaitosten nettosähkötehot ovat neljästä yhdeksään megawattia. Voimalaitosyksiköiden energiantuotanto määritetään Turengin lämpökuormien perusteella. Tuotannon määrityksessä apuna käytetään WinTEHO –ohjelmistoa, johon luodaan tarvittavat energiatiedostot. Kannattavuuslaskelmat suoritetaan vertaamalla investointivaihtoehtojen aiheuttamia vuotuisia kassavirtoja nykyisen tuotannon mukaisiin kassavirtoihin. Kassavirtalaskelmasta saadaan kullekin vaihtoehdolle nettonykyarvo, sisäinen korko ja takaisinmaksuaika. Tarkastelun tuloksena saatiin, että voimalaitosvaihtoehdoista kannattavin on investointi yhteen kaasumoottoriin, jolla tuotetaan sähkön lisäksi vain kaukolämpöä. Alhaisilla sähkön hinnoilla kaasuturbiinivaihtoehdot ovat suunnilleen yhtä kannattavia. Investointien nykyarvo valitulla korkokannalla on positiivinen, kun sähkön markkinahinnan keskiarvo tuotantokaudella ylittää likimain tason 130 mk/MWh. Nykyisillä markkinahinnoilla investoinnit eivät ole kannattavia. Investoiminen uuteen kaasumoottoriin tai -turbiiniin osoittautui kannattavammaksi kuin sähkön tuotannon aloittaminen laitoksen nykyisellä höyryturbiinilla. Merkittävin syy tähän oli höyryturbiinituotannon korkeat henkilöstökustannukset. Tehty selvitys tukee vallitsevaa käsitystä, että nykytekniikalla sähkön ja lämmön yhteistuotanto on taloudellisesti kilpailukykyistä myös pienessä kokoluokassa.

Optimizing nozzle flow in laser cutting

The purpose of this study was to investigate different laser cutting nozzles, nozzle flows and possibilities to improve nozzle flow. Another goal was to design new nozzle configuration in which laser cutting would succeed with better cutting speed and smaller gas consumption. Nozzles and nozzle flows were studied with various methods. Computational fluid dynamics was used to calculate old, convergent nozzles and new convergent-divergent nozzles. Measurement apparatus was used to measure both nozzle types. In cutting tests different materials were cut with new nozzles. With the use of design convergent-divergent nozzles 25 % better cutting speed and 33 % smaller gas consumption were achieved when cutting quality was good. Computational fluid dynamics was also discovered to be useful aid in nozzle design.

Pain-evoked alterations on gingival blood flow and gingival crevicular fluid (GCF) neuropeptide SP and collagenase-2 (MMP-8) levels

Previous studies have demonstrated that clinical pulpal pain can induce the expression of pro-inflammatory neuropeptides in the adjacent gingival crevice fluid (GCF). Vasoactive agents such as substance P (SP) are known to contribute to the inflammatory type of pain and are associated with increased blood flow. More recent animal studies have shown that application of capsaicin on alveolar mucosa provokes pain and neurogenic vasodilatation in the adjacent gingiva. Pain-associated inflammatory reactions may initiate expression of several pro- and anti-inflammatory mediators. Collagenase-2 (MMP-8) has been considered to be the major destructive protease, especially in the periodontitis-affected gingival crevice fluid (GCF). MMP-8 originates mostly from neutrophil leukocytes, the first line of defence cells that exist abundantly in GCF, especially in inflammation. With this background, we wished to clarify the spatial extensions and differences between tooth-pain stimulation and capsaicin-induced neurogenic vasodilatation in human gingiva. Experiments were carried out to study whether tooth stimulation and capsaicin stimulation of alveolar mucosa would induce changes in GCF MMP-8 levels and whether tooth stimulation would release neuropeptide SP in GCF. The experiments were carried out on healthy human volunteers. During the experiments, moderate and high intensity painful tooth stimulation was performed by a constant current tooth stimulator. Moderate tooth stimulation activates A-delta fibres, while high stimulation also activates C-fibres. Painful stimulation of the gingiva was achieved by topical application of capsaicin-moistened filter paper on the mucosal surface. Capsaicin is known to activate selectively nociceptive C-fibres of stimulated tissue. Pain-evoked vasoactive changes in gingivomucosal tissues were mapped by laser Doppler imaging (LDI), which is a sophisticated and non-invasive method for studying e.g. spatial and temporal characteristics of pain- and inflammation-evoked blood flow changes in gingivomucosal tissues. Pain-evoked release of MMP-8 in GCF samples was studied by immunofluorometric assay (IFMA) and Western immunoblotting. The SP levels in GCF were analysed by Enzyme immunoassay (EIA). During the experiments, subjective stimulus-evoked pain responses were determined by a visual analogue pain scale. Unilateral stimulation of alveolar mucosa and attached gingiva by capsaicin evoked a distinct neurogenic vasodilatation in the ipsilateral gingiva, which attenuated rapidly at the midline. Capsaicin stimulation of alveolar mucosa provoked clear inflammatory reactions. In contrast to capsaicin stimuli, tooth stimulation produced symmetrical vasodilatations bilaterally in the gingiva. The ipsilateral responses were significantly smaller during tooth stimulation than during capsaicin stimuli. The current finding – that tooth stimulation evokes bilateral vasodilatation while capsaicin stimulation of the gingiva mainly produces unilateral vasodilatation – emphasises the usefulness of LDI in clarifying spatial features of neurogenic vasoactive changes in the intra-oral tissues. Capsaicin stimulation of the alveolar mucosa induced significant elevations in MMP-8 levels and activation in GCF of the adjacent teeth. During the experiments, no marked changes occurred in MMP-8 levels in the GCF of distantly located teeth. Painful stimulation of the upper incisor provoked elevations in GCF MMP-8 and SP levels of the stimulated tooth. The GCF MMP-8 and SP levels of the non-stimulated teeth were not changed. These results suggest that capsaicin-induced inflammatory reactions in gingivomucosal tissues do not cross the midline in the anterior maxilla. The enhanced reaction found during stimulation of alveolar mucosa indicates that alveolar mucosa is more sensitive to chemical irritants than the attached gingiva. Analysis of these data suggests that capsaicin-evoked neurogenic inflammation in the gingiva can trigger the expression and activation of MMP-8 in GCF of the adjacent teeth. In this study, it is concluded that experimental tooth pain at C-fibre intensity can induce local elevations in MMP-8 and SP levels in GCF. Depending on the role of MMP-8 in inflammation, in addition to surrogated tissue destruction, the elevated MMP-8 in GCF may also reflect accelerated local defensive and anti-inflammatory reactions.

Gas-phase photocatalytic oxidation of volatile organic compounds

Substances emitted into the atmosphere by human activities in urban and industrial areas cause environmental problems such as air quality degradation, respiratory diseases, climate change, global warming, and stratospheric ozone depletion. Volatile organic compounds (VOCs) are major air pollutants, emitted largely by industry, transportation and households. Many VOCs are toxic, and some are considered to be carcinogenic, mutagenic, or teratogenic. A wide spectrum of VOCs is readily oxidized photocatalytically. Photocatalytic oxidation (PCO) over titanium dioxide may present a potential alternative to air treatment strategies currently in use, such as adsorption and thermal treatment, due to its advantageous activity under ambient conditions, although higher but still mild temperatures may also be applied. The objective of the present research was to disclose routes of chemical reactions, estimate the kinetics and the sensitivity of gas-phase PCO to reaction conditions in respect of air pollutants containing heteroatoms in their molecules. Deactivation of the photocatalyst and restoration of its activity was also taken under consideration to assess the practical possibility of the application of PCO to the treatment of air polluted with VOCs. UV-irradiated titanium dioxide was selected as a photocatalyst for its chemical inertness, non-toxic character and low cost. In the present work Degussa P25 TiO2 photocatalyst was mostly used. In transient studies platinized TiO2 was also studied. The experimental research into PCO of following VOCs was undertaken: - methyl tert-butyl ether (MTBE) as the basic oxygenated motor fuel additive and, thus, a major non-biodegradable pollutant of groundwater; - tert-butyl alcohol (TBA) as the primary product of MTBE hydrolysis and PCO; - ethyl mercaptan (ethanethiol) as one of the reduced sulphur pungent air pollutants in the pulp-and-paper industry; - methylamine (MA) and dimethylamine (DMA) as the amino compounds often emitted by various industries. The PCO of VOCs was studied using a continuous-flow mode. The PCO of MTBE and TBA was also studied by transient mode, in which carbon dioxide, water, and acetone were identified as the main gas-phase products. The volatile products of thermal catalytic oxidation (TCO) of MTBE included 2-methyl-1-propene (2-MP), carbon monoxide, carbon dioxide and water; TBA decomposed to 2-MP and water. Continuous PCO of 4 TBA proceeded faster in humid air than dry air. MTBE oxidation, however, was less sensitive to humidity. The TiO2 catalyst was stable during continuous PCO of MTBE and TBA above 373 K, but gradually lost activity below 373 K; the catalyst could be regenerated by UV irradiation in the absence of gas-phase VOCs. Sulphur dioxide, carbon monoxide, carbon dioxide and water were identified as ultimate products of PCO of ethanethiol. Acetic acid was identified as a photocatalytic oxidation by-product. The limits of ethanethiol concentration and temperature, at which the reactor performance was stable for indefinite time, were established. The apparent reaction kinetics appeared to be independent of the reaction temperature within the studied limits, 373 to 453 K. The catalyst was completely and irreversibly deactivated with ethanethiol TCO. Volatile PCO products of MA included ammonia, nitrogen dioxide, nitrous oxide, carbon dioxide and water. Formamide was observed among DMA PCO products together with others similar to the ones of MA. TCO for both substances resulted in the formation of ammonia, hydrogen cyanide, carbon monoxide, carbon dioxide and water. No deactivation of the photocatalyst during the multiple long-run experiments was observed at the concentrations and temperatures used in the study. PCO of MA was also studied in the aqueous phase. Maximum efficiency was achieved in an alkaline media, where MA exhibited high fugitivity. Two mechanisms of aqueous PCO – decomposition to formate and ammonia, and oxidation of organic nitrogen directly to nitrite - lead ultimately to carbon dioxide, water, ammonia and nitrate: formate and nitrite were observed as intermediates. A part of the ammonia formed in the reaction was oxidized to nitrite and nitrate. This finding helped in better understanding of the gasphase PCO pathways. The PCO kinetic data for VOCs fitted well to the monomolecular Langmuir- Hinshelwood (L-H) model, whereas TCO kinetic behaviour matched the first order process for volatile amines and the L-H model for others. It should be noted that both LH and the first order equations were only the data fit, not the real description of the reaction kinetics. The dependence of the kinetic constants on temperature was established in the form of an Arrhenius equation.