Magnesium hydroxide-based peroxide bleaching of high-brightness mechanical pulps

A high final brightness is desired in most paper and board products. This requires bleaching processes that are able to produce high-brightness pulps. Mechanical pulps are widely bleached for high brightness using alkaline hydrogen peroxide with traditional sodium hydroxide and sodium silicate as additives. With high doses however, peroxide bleaching causes high organic loads in the mill effluent and anionic trash carry-over to papermaking. To alleviate the problems that arise from the use of sodium-based additives in peroxide bleaching, interest in the use of alternative magnesium-based chemicals has increased. In this study, a new, technical high-purity magnesium hydroxide-based bleaching additive was evaluated on laboratory-scale, pilot-scale and mill-scale experiments and trials for its ability to produce a high brightness in peroxide bleaching without the known problems of sodium-based chemicals. The key findings of this study include: a high brightening potential of peroxide bleaching using the Mg(OH)2-based additive, significant reductions (40-70%) in all categories of environmental load, and cationic demand lowered by 60-70% in bleached pulp with no loss in strength properties or in sheet bulk. When used in TMP refiner bleaching, the Mg(OH)2-based additive resulted in savings in specific energy consumption and provided a good bleaching response.

Action of laccase on mechanical softwood pulps

Träfibrernas naturliga egenskaper begränsar deras användning i många tillämpningar. Träfibrernas egenskaper kan modifieras genom att binda nya komponenter med önskade egenskaper till fiberns yta. DI Stina Grönqvist bevisade i sin avhandling att nya funktionella grupper kan bindas till ligninhaltiga träfibrer genom att aktivera ytligninet med lackasenzym. Resultaten kan utnyttjas till att förbättra de traditionella träfibrernas och fiberprodukternas egenskaper samt att hitta nya tillämpningar för träfibrerna. ”Om träfibrerna t.ex. modifieras så att de blir vattenavstötande kan de modifierade träfibrerna användas istället för plast i förpackningar” berättar Stina Grönqvist. Syftet med denna avhandling var att undersöka effekterna av lackasenzym på TMP (termomekanisk massa) och dess fraktioner. I Finland tillverkas TMP av gran och massan innehåller rikligt med lignin. När ytligninet på träfibrernas yta modifieras med hjälp av oxiderande enzymer, såsom lackas, bildas reaktiva radikaler i ligninen på fibrernas ytor. De bildade radikalerna kan utnyttjas till att binda komponenter med nya egenskaper till fiberytan. För att kunna utnyttja den fulla potentialen av den lackasbaserade modifieringsmetoden behövs mera information om så väl de faktorer som påverkar bildningen av radikaler som om mekanismerna hur de nya komponenterna binds till fibrerna ___________________________________ Puukuitujen luontaiset ominaisuudet rajoittavat niiden hyödyntämistä joissakin sovelluksissa. Ominaisuuksia voidaan kuitenkin muuttaa liittämällä kuidun pintaan uusia yhdisteitä. DI Stina Grönqvist osoitti väitöstyössään, että uusia kuitujen ominaisuuksia muuttavia funktionaalisia yhdisteitä voidaan sitoa ligniinipitoisiin puukuituihin aktivoimalla kuitujen pinnan ligniiniä lakkaasi-entsyymillä. Tutkimuksen tuloksia voidaan hyödyntää ligniinipitoisten puukuitujen ominaisuuksien parantamiseen ja jopa täysin uusien ominaisuuksien kehittämiseen. ”Jos kuituja muutetaan vettä hylkiväksi sitomalla kuituihin vettä hylkiviä yhdisteitä entsyymien avulla, voidaan puukuituja käyttää korvaamaan muovia pakkauksissa”, kertoo Stina Grönqvist. Väitöstyön kohteena oli TMP-massan eli kuumahiertämällä valmistetun mekaanisen puumassojen ja niiden fraktioiden muokkaaminen lakkaasi-entsyymillä (TMP, Thermomechanical pulp). Suomalainen TMP-massa valmistetaan kuusesta ja siinä on runsaasti muokkaamatonta ligniiniä. Kun puukuidun pinnan ligniiniä muokataan hapettavilla entsyymeillä, muodostuu kuidun pintaan reaktiivisia radikaaleja. Syntyneiden radikaalien avulla kuituihin voidaan liittää yhdisteitä, jotka antavat kuidulle uusia ominaisuuksia. Menetelmän tarjoamien mahdollisuuksien hyödyntämiseksi tarvitaan tietoa kuidun radikalisointiin ja yhdisteiden liittämiseen vaikuttavista tekijöistä.

Comparison study of two competing models of an all mechanical power transmission system

A comparison between two competing models of an all mechanical power transmission system is studied by using Dymola –software as the simulation tool. This tool is compared with Matlab/ Simulink –software by using functionality, user-friendliness and price as comparison criteria. In this research we assume that the torque is balanceable and transmission ratios are calculated. Using kinematic connection sketches of the two transmission models, simulation models are built into the Dymola simulation environment. Models of transmission systems are modified according to simulation results to achieve a continuous variable transmission ratio. Simulation results are compared between the two transmission systems. The main features of Dymola and MATLAB/ Simulink are compared. Advantages and disadvantages of the two softwares are analyzed and compared.

Mechanical design and analysis of modular active magnetic bearing test rig

Tässä työssä on tutkittu modulaarisen aktiivimagneettilaakeroidun koelaitteen mekaanista suunnittelua ja analysointia. Suurnopeusroottorin suunnittelun teoria on esitelty. Lisäksi monia analyyttisiä mallinnusmenetelmiä mekaanisten kuormitusten mallintamiseksi on esitelty. Koska kyseessä on suurnopeussähkökone, roottoridynamiikka ja sen soveltuvuus suunnittelussa on esitelty. Magneettilaakerien rakenteeseen ja toimintaan on tutustuttu osana tätä työtä. Kirjallisuuskatsaus nykyisistä koelaitteista esimerkiksi komponenttien ominaisuuksien tunnistamiseen ja roottoridynamiikan tutkimuksiin on esitelty. Työn rajauksena on konseptisuunnittelu muunneltavalle magneettilaakeroidulle (AMB) koelaitteelle ja suunnitteluprosessin dokumentointi. Muunneltavuuteen päädyttiin, koska se mahdollistaa erilaisten komponenttiasetteluiden testaamisen erilaisille magneettilaakerikokoonpanoille ja roottoreille. Pääpaino tässä työssä on suurnopeus induktiokoneen roottorin suunnittelussa ja mallintamisessa. Modulaaristen toimilaitteiden kuten magneettilaakerien ja induktiosähkömoottorin rakenne on esitelty ja modulaarisen rakenteen käytettävyyden hyödyistä koelaitekäytössä on dokumentoitu. Analyyttisiä ja elementtimenetelmään perustuvia tutkimusmenetelmiä on käytetty tutkittaessa suunniteltua suurnopeusroottoria. Suunnittelun ja analysoinnin tulokset on esitelty ja verrattu keskenään eri mallinnusmenetelmien välillä. Lisäksi johtopäätökset sähkömagneettisten osien liittämisen monimutkaisuudesta ja vaatimuksista roottoriin ja toimilaitteisiin sekä mekaanisten että sähkömagneettisten ominaisuuksien optimoimiseksi on dokumentoitu.

Microscopic variability in mechanical defence and herbivory response in microphyllous leaves of tropical herb species from Serra do Cipó, Brazil

Tropical high altitude grasslands present several species with both microphyllous and highly sclerophyllous leaves, and co-occur in specific soil patches, thus exposed to identical environments. In this article we describe herbivory among co-occurring microphyllous species in a tropical high altitude grassland ecosystem of Serra do Cipó, Minas Gerais state, and we tested the effect of variable anatomic traits on leaf herbivory patterns. Leaf anatomical traits were investigated for Baccharis imbricata Heering , Lavoisiera imbricata DC. and L. subulata Triana (focal species). Herbivory was measured from branches and leaves of individual plants and compared among co-occurring species within one multispecific shrub patch and among L. subulata individuals from this patch and an adjacent monospecific patch. For all present plant species and individuals we estimated the proportion of leaves with different levels of area lost. For the focal species, six leaves were sorted and taken for histological sectioning, in order to allow precise measures of defensive structures. Relative mean leaf area lost differed significantly among the six species found in the multispecific patch. Lavoisiera subulata individuals were more attacked in the multispecific than in the monospecific patch. Leaf margin protection traits in both B. imbricata and L. imbricata showed significant effect against herbivory. Data suggest that some anatomic traits have direct effect against herbivory but their effect are not clearly perceptible among branches within individual plants or among plants within the same species.

Myocyte necrosis is the basis for fibrosis in renovascular hypertensive rats

The pathogenesis of fibrosis and the functional features of pressure overload myocardial hypertrophy are still controversial. The objectives of the present study were to evaluate the function and morphology of the hypertrophied myocardium in renovascular hypertensive (RHT) rats. Male Wistar rats were sacrificed at week 4 (RHT4) and 8 (RHT8) after unilateral renal ischemia (Goldblatt II hypertension model). Normotensive rats were used as controls. Myocardial function was analyzed in isolated papillary muscle preparations, morphological features were defined by light microscopy, and myocardial hydroxyproline concentration (HOP) was determined by spectrophotometry. Renal artery clipping resulted in elevated systolic arterial pressure (RHT4: 178 ± 19 mmHg and RHT8: 194 ± 24 mmHg, P<0.05 vs control: 123 ± 7 mmHg). Myocardial hypertrophy was observed in both renovascular hypertensive groups. The myocardial HOP concentration was increased in the RHT8 group (control: 2.93 ± 0.38 µg/mg; RHT4: 3.02 ± 0.40 µg/mg; RHT8: 3.44 ± 0.45 µg/mg of dry tissue, P<0.05 vs control and RHT4 groups). The morphological study demonstrated myocyte necrosis, vascular damage and cellular inflammatory response throughout the experimental period. The increased cellularity was more intense in the adventitia of the arterioles. As a consequence of myocyte necrosis, there was an early, local, conjunctive stroma collapse with disarray and thickening of the argyrophilic interstitial fibers, followed by scarring. The functional data showed an increased passive myocardial stiffness in the RHT4 group. We conclude that renovascular hypertension induces myocyte and arteriole necrosis. Reparative fibrosis occurred as a consequence of the inflammatory response to necrosis. The mechanical behavior of the isolated papillary muscle was normal, except for an early increased myocardial passive stiffness

Quantitative Magnetic Resonance Imaging of the Liver and Heart In Iron Overload

Systemic iron overload (IO) is considered a principal determinant in the clinical outcome of different forms of IO and in allogeneic hematopoietic stem cell transplantation (alloSCT). However, indirect markers for iron do not provide exact quantification of iron burden, and the evidence of iron-induced adverse effects in hematological diseases has not been established. Hepatic iron concentration (HIC) has been found to represent systemic IO, which can be quantified safely with magnetic resonance imaging (MRI), based on enhanced transverse relaxation. The iron measurement methods by MRI are evolving. The aims of this study were to implement and optimise the methodology of non-invasive iron measurement with MRI to assess the degree and the role of IO in the patients. An MRI-based HIC method (M-HIC) and a transverse relaxation rate (R2*) from M-HIC images were validated. Thereafter, a transverse relaxation rate (R2) from spin-echo imaging was calibrated for IO assessment. Two analysis methods, visual grading and rSI, for a rapid IO grading from in-phase and out-of-phase images were introduced. Additionally, clinical iron indicators were evaluated. The degree of hepatic and cardiac iron in our study patients and IO as a prognostic factor in patients undergoing alloSCT were explored. In vivo and in vitro validations indicated that M-HIC and R2* are both accurate in the quantification of liver iron. R2 was a reliable method for HIC quantification and covered a wider HIC range than M-HIC and R2*. The grading of IO was able to be performed rapidly with the visual grading and rSI methods. Transfusion load was more accurate than plasma ferritin in predicting transfusional IO. In patients with hematological disorders, the prevalence of hepatic IO was frequent, opposite to cardiac IO. Patients with myelodysplastic syndrome were found to be the most susceptible to IO. Pre-transplant IO predicted severe infections during the early post-transplant period, in contrast to the reduced risk of graft-versus-host disease. Iron-induced, poor transplantation results are most likely to be mediated by severe infections.

Use of nucleotides in weanling rats with diarrhea induced by a lactose overload: effect on the evolution of diarrhea and weight and on the histopathology of intestine, liver and spleen

Until recently, dietary sources of nucleotides were thought not to be essential for good nutrition. Certain states with higher metabolic demands may require larger amounts that cannot be provided by endogenous production. The objective of the present study was to determine the action of nucleotides on the recovery from lactose-induced diarrhea in weaned rats. Thirty-six weanling Fisher rats were divided into two groups. Group 1 received a standard diet and group 2 received a diet containing lactose in place of starch. On the 10th day, six animals per group were sacrificed for histopathological evaluation. The remaining animals were divided into two other subgroups, each with 6 animals, receiving a control diet, a control diet with nucleotides (0.05% adenosine monophosphate, 0.05% guanosine monophosphate, 0.05% cytidine monophosphate, 0.05% uridine monophosphate and 0.05% inosine monophosphate), a diet with lactose, and a diet with lactose and nucleotides. On the 32nd day of the experiment all animals were sacrificed. Animals with diarrhea weighed less than animals without diarrhea. The introduction of nucleotides did not lead to weight gain. Mean diet consumption was lower in the group that continued to ingest lactose, with the group receiving lactose plus nucleotides showing a lower mean consumption. Animals receiving lactose had inflammatory reaction and deposits of periodic acid-Schiff-positive material in intestinal, hepatic and splenic tissues. The introduction of nucleotides led to an improvement of the intestinal inflammatory reaction. In lactose-induced diarrhea, when the stimulus is maintained - lactose overload - the nucleotides have a limited action on the weight gain and on recovery of intestinal morphology, although they have a protective effect on hepatic injury and improve the inflammatory response.

Plasma insulin levels are increased by sertraline in rats under oral glucose overload

Recognition and control of depression symptoms are important to increase patient compliance with treatment and to improve the quality of life of diabetic patients. Clinical studies indicate that selective serotonin reuptake inhibitors (SSRI) are better antidepressants for diabetic patients than other drugs. However, preclinical trials have demonstrated that not all SSRI reduce plasma glucose levels. In fact, fluoxetine increases and sertraline decreases glycemia in diabetic and non-diabetic rats. In the present study we evaluated plasma insulin levels during fasting and after glucose overload after treatment with sertraline. Adult male Wistar rats were fasted and treated with saline or 30 mg/kg sertraline and submitted or not to glucose overload (N = 10). Blood was collected and plasma insulin was measured. The mean insulin levels were: fasting group: 25.9 ± 3.86, sertraline + fasting group: 31.10 ± 2.48, overload group: 34.1 ± 3.40, and overload + sertraline group: 43.73 ± 5.14 µU/ml. Insulinemia was significantly increased in the overload + sertraline group. There were no differences between the other groups. No difference in glucose/insulin ratios could be detected between groups. The overload + sertraline group was the only one in which a significant number of individuals exceeded the upper confidence limit of insulin levels. This study demonstrates that sertraline increases glucose-stimulated insulin secretion without any change in peripheral insulin sensitivity.

Presurgical ketoprofen, but not morphine, dipyrone, diclofenac or tenoxicam, preempts post-incisional mechanical allodynia in rats

The treatment of pain before it initiates may prevent the persistent pain-induced changes in the central nervous system that amplify pain long after the initial stimulus. The effects of pre- or postoperative intraperitoneal administration of morphine (2 to 8 mg/kg), dipyrone (40 and 80 mg/kg), diclofenac (2 to 8 mg/kg), ketoprofen (10 and 20 mg/kg), and tenoxicam (10 and 20 mg/kg) were studied in a rat model of post-incisional pain. Groups of 5 to 8 male Wistar rats (140-160 g) were used to test each drug dose. An incision was made on the plantar surface of a hind paw and the changes in the withdrawal threshold to mechanical stimulation were evaluated with Von Frey filaments at 1, 2, 6 and 24 h after the surgery. Tenoxicam was given 12 or 6 h preoperatively, whereas the remaining drugs were given 2 h or 30 min preoperatively. Postoperative drugs were all given 5 min after surgery. No drug abolished allodynia when injected before or after surgery, but thresholds were significantly higher than in control during up to 2 h following ketoprofen, 6 h following diclofenac, and 24 h following morphine, dipyrone or tenoxicam when drugs were injected postoperatively. Significant differences between pre- and postoperative treatments were obtained only with ketoprofen administered 30 min before surgery. Preoperative (2 h) intraplantar, but not intrathecal, ketoprofen reduced the post-incisional pain for up to 24 h after surgery. It is concluded that stimuli generated in the inflamed tissue, rather than changes in the central nervous system are relevant for the persistence of pain in the model of post-incisional pain.

Effect of ultrastructural features on mechanical properties of softwood fiber

The main objective of this study was to develop mathematical model capable to describe the effect of ultrastructural features on the longitudinal modulus of elasticity of softwood fiber. Another objective was to identify, based on ultrastructural features, a potential explanatory factor for the mechanical difference between Norway spruce and Scots pine fibers and to demonstrate its influence utilizing developed modelling tools. According to the literature, the main difference between the pine and spruce fibers is the pit structure, which is clearly different in these fibers. The spruce fiber contains a lot of tiny pits, whereas the pits of the pine fiber are larger and the total number of them is smaller. The effect of the pits on the longitudinal modulus of elasticity of fiber is studied with both the analytical and the numerical model. The results show that, although the spruce fiber seems to contain clearly more pits, larger pits appearing in the pine fiber turn out to have a stronger influence on the longitudinal modulus of elasticity of the fiber. The effect of local variation of microfibril angle which occurs near the pits seems to be minor. Moreover, the results suggest that spruce fibers may have higher ultimate strength due to the more uniform straining behavior.

Baroreflex function in conscious rats submitted to iron overload

Our hypothesis is that iron accumulated in tissue, rather than in serum, may compromise cardiovascular control. Male Fischer 344 rats weighing 180 to 220 g were divided into 2 groups. In the serum iron overload group (SIO, N = 12), 20 mg elemental iron was injected ip daily for 7 days. In the tissue iron overload group (TIO, N = 19), a smaller amount of elemental iron was injected (10 mg, daily) for 5 days followed by a resting period of 7 days. Reflex heart rate responses were elicited by iv injections of either phenylephrine (0.5 to 5.0 µg/kg) or sodium nitroprusside (1.0 to 10.0 µg/kg). Baroreflex curves were determined and fitted to sigmoidal equations and the baroreflex gain coefficient was evaluated. To evaluate the role of other than a direct effect of iron on tissue, acute treatment with the iron chelator deferoxamine (20 mg/kg, iv) was performed on the TIO group and the baroreflex was re-evaluated. At the end of the experiments, evaluation of iron levels in serum confirmed a pronounced overload for the SIO group (30-fold), in contrast to the TIO group (2-fold). Tissue levels of iron, however, were higher in the TIO group. The SIO protocol did not produce significant alterations in the baroreflex curve response, while the TIO protocol produced a nearly 2-fold increase in baroreflex gain (-4.34 ± 0.74 and -7.93 ± 1.08 bpm/mmHg, respectively). The TIO protocol animals treated with deferoxamine returned to sham levels of baroreflex gain (-3.7 ± 0.3 sham vs -3.6 ± 0.2 bpm/mmHg) 30 min after the injection. Our results indicate an effect of tissue iron overload on the enhancement of baroreflex sensitivity.

Effect of iron overload on the severity of liver histologic alterations and on the response to interferon and ribavirin therapy of patients with hepatitis C infection

The objective of the present study was to determine the presence of hepatic iron overload in patients with chronic HCV infection and to correlate it with histologic alterations, HCV genotype and response to therapy. Liver tissue samples from 95 patients with chronic hepatitis C were divided into two groups: group I, presence of iron overload in hepatic tissue (Perls' staining) and group II, no iron overload. Hepatic iron overload was detected in 30 (31.6%) of 95 patients. Of the 69 patients tested by genotyping, 49 (71.01%) were genotype 1 and 20 (28.99%) genotype non-1. Iron overload was detected in 14 (28.6%) patients with genotype 1 and in 6 (30%) with genotype non-1 (P = 0.906). There was a significant difference in fibrosis stage between groups (P = 0.005). In group I (N = 30), one patient had stage F0/F1 of fibrosis, while in group II (N = 65), 22 (33.8%) patients had minimal or no fibrosis. Fibrosis stage F2/F3 was observed in 70% of group I patients compared to 46.2% of group II. Eighty-five patients were treated with a combination of interferon and ribavirin; 29 of them (34.1%) had a sustained virologic response and 8 (27.6%) of them had hepatic iron overload. Iron overload was detected in 18 (32.1%) of the 56 non-responders (P = 0.73). Hepatic iron overload was frequent among patients with chronic hepatitis C and was associated with a more severe stage of liver fibrosis. There was no association between iron overload and HCV genotype and response to interferon and ribavirin therapy.

The importance of the Thr17 residue of phospholamban as a phosphorylation site under physiological and pathological conditions

The sarcoplasmic reticulum (SR) Ca2+-ATPase (SERCA2a) is under the control of an SR protein named phospholamban (PLN). Dephosphorylated PLN inhibits SERCA2a, whereas phosphorylation of PLN at either the Ser16 site by PKA or the Thr17 site by CaMKII reverses this inhibition, thus increasing SERCA2a activity and the rate of Ca2+ uptake by the SR. This leads to an increase in the velocity of relaxation, SR Ca2+ load and myocardial contractility. In the intact heart, ß-adrenoceptor stimulation results in phosphorylation of PLN at both Ser16 and Thr17 residues. Phosphorylation of the Thr17 residue requires both stimulation of the CaMKII signaling pathways and inhibition of PP1, the major phosphatase that dephosphorylates PLN. These two prerequisites appear to be fulfilled by ß-adrenoceptor stimulation, which as a result of PKA activation, triggers the activation of CaMKII by increasing intracellular Ca2+, and inhibits PP1. Several pathological situations such as ischemia-reperfusion injury or hypercapnic acidosis provide the required conditions for the phosphorylation of the Thr17 residue of PLN, independently of the increase in PKA activity, i.e., increased intracellular Ca2+ and acidosis-induced phosphatase inhibition. Our results indicated that PLN was phosphorylated at Thr17 at the onset of reflow and immediately after hypercapnia was established, and that this phosphorylation contributes to the mechanical recovery after both the ischemic and acidic insults. Studies on transgenic mice with Thr17 mutated to Ala (PLN-T17A) are consistent with these results. Thus, phosphorylation of the Thr17 residue of PLN probably participates in a protective mechanism that favors Ca2+ handling and limits intracellular Ca2+ overload in pathological situations.