The Effects of Recycling on the Hygroexpansivity of Thermomechanical Pulp

The objectives of this thesis were 1) to determine the effects of recycling and increased drying temperature on the hygroexpansivity of the fibers and 2) to investigate the role of beating on the hygroexpansivity of the fibers. A never-dried thermomechanical pulp was obtained and separated into three samples. Handsheets were produced, dried, and placed in a conditioning room. Sample one was air dried (77°F), sample two was dried at 155°F and sample three was dried at 250°F, respectively. Five handsheet samples at each varying temperature were taken and the hygroexpansivity was tested and calculated for each sheet using the equation BC= ΔL/L. B is the hygroexpansivity coefficient, C is the moisture content determined by W-Wo/Wo, where W is final weight of saturated sample after hygroexpansivity test and Wo is initial O.D. weight of sample. ΔL/L is defined as the strain of the sample. After testing the hygroexpansivity of the sheets, the samples were repulped in a British Disintegrator to resemble the recycling process. Once disintegrated, a series of handsheets were again made for each respective temperature, continuing for three recycles. The effects of beating on the hygroexpansivity of the sheet were also investigated. The freeness of the thermomechanical pulp was initially determined and handsheets were made and dried at 250°F, then tested for hygroexpansivity. Once tested, the sheets were disintegrated following the aforementioned process. The pulp was then taken to a PFI mill and beaten to the initial freeness of the pulp before recycling occurred. Again, after the series of recycling and beating, the sheets were tested for hygroexpansivity. Four recycles were completed. It was determined that as the number of recycles and drying temperature increased, the hygroexpansivity of the sheets decreased, becoming more dimensionally stable. Recycling and drying caused an increase of the crystalline region and hardening of the fibers. The fiber absorbed less water, therefore, causing the sheet to react less to the rising humidity. The effects of beating on the hygroexpansivity were very peculiar. In the past, when chemical pulps have been tested the hygroexpansivity of the pulp increased with beating due to fibrillization of the fibers exposing the region of the fiber that is hydrophilic causing dimensional instability. For the mechanical pulp tested, as beating was instituted, the hygroexpansivity of the sheet actually decreased, meaning increased dimensional stability. This trend was true for each of the recycles, which is exactly opposite of what is believed. This may be attributed to the lignin and hemicelluloses present in mechanical pulps, which are not present in chemical pulps

LC-MS proteomics analysis of the iInsulin/IGF-1-deficient Caenorhabditis elegans daf-2(e1370) mutant reveals extensive restructuring of intermediary metabolism

The insulin/IGF-1 receptor is a major known determinant of dauer formation, stress resistance, longevity, and metabolism in Caenorhabditis elegans. In the past, whole-genome transcript profiling was used extensively to study differential gene expression in response to reduced insulin/IGF-1 signaling, including the expression levels of metabolism-associated genes. Taking advantage of the recent developments in quantitative liquid chromatography mass spectrometry (LC-MS)-based proteomics, we profiled the proteomic changes that occur in response to activation of the DAF-16 transcription factor in the germline-less glp-4(bn2);daf-2(e1370) receptor mutant. Strikingly, the daf-2 profile suggests extensive reorganization of intermediary metabolism, characterized by the upregulation of many core intermediary metabolic pathways. These include glycolysis/gluconeogenesis, glycogenesis, pentose phosphate cycle, citric acid cycle, glyoxylate shunt, fatty acid beta-oxidation, one-carbon metabolism, propionate and tyrosine catabolism, and complexes I, II, III, and V of the electron transport chain. Interestingly, we found simultaneous activation of reciprocally regulated metabolic pathways, which is indicative of spatiotemporal coordination of energy metabolism and/or extensive post-translational regulation of these enzymes. This restructuring of daf-2 metabolism is reminiscent to that of hypometabolic dauers, allowing the efficient and economical utilization of internal nutrient reserves and possibly also shunting metabolites through alternative energy-generating pathways to sustain longevity

Scanning tunneling microscopy and spectroscopy at low temperatures of the (110) surface of Te doped GaAs single crystals

We have performed voltage dependent imaging and spatially resolved spectroscopy on the (110) surface of Te doped GaAs single crystals with a low temperature scanning tunneling microscope (STM). A large fraction of the observed defects are identified as Te dopant atoms which can be observed down to the fifth subsurface layer. For negative sample voltages, the dopant atoms are surrounded by Friedel charge density oscillations. Spatially resolved spectroscopy above the dopant atoms and above defect free areas of the GaAs (110) surface reveals the presence of conductance peaks inside the semiconductor band gap. The appearance of the peaks can be linked to charges residing on states which are localized within the tunnel junction area. We show that these localized states can be present on the doped GaAs surface as well as at the STM tip apex.Comment: 8 pages, 8 figures, accepted for publication in PR

Noninvasive mechanical ventilation in high-risk pulmonary infections: a clinical review

The aim of this article was to review the role of noninvasive ventilation (NIV) in acute pulmonary infectious diseases, such as severe acute respiratory syndrome (SARS), H1N1 and tuberculosis, and to assess the risk of disease transmission with the use of NIV from patients to healthcare workers. We performed a clinical review by searching Medline and EMBASE. These databases were searched for articles on "clinical trials" and "randomised controlled trials". The keywords selected were non-invasive ventilation pulmonary infections, influenza-A (H1N1), SARS and tuberculosis. These terms were cross-referenced with the following keywords: health care workers, airborne infections, complications, intensive care unit and pandemic. The members of the International NIV Network examined the major results regarding NIV applications and SARS, H1N1 and tuberculosis. Cross-referencing mechanical ventilation with SARS yielded 76 studies, of which 10 studies involved the use of NIV and five were ultimately selected for inclusion in this review. Cross-referencing with H1N1 yielded 275 studies, of which 27 involved NIV. Of these, 22 were selected for review. Cross-referencing with tuberculosis yielded 285 studies, of which 15 involved NIV and from these seven were selected. In total 34 studies were selected for this review. NIV, when applied early in selected patients with SARS, H1N1 and acute pulmonary tuberculosis infections, can reverse respiratory failure. There are only a few reports of infectious disease transmission among healthcare workers

Determinants and impact of multidrug antibiotic resistance in pathogens causing ventilator-associated-pneumonia

Introduction The idea that multidrug resistance (MDR) to antibiotics in pathogens causing ventilator-associated pneumonia (VAP) is an independent risk factor for adverse outcome is still debated. We aimed to identify the determinants of MDR versus non-MDR microbial aetiology in VAP and assessed whether MDR versus non-MDR VAP was independently associated with increased 30-day mortality. Methods We performed a retrospective analysis of a prospectively registered cohort of adult patients with microbiologically confirmed VAP, diagnosed at a university hospital intensive care unit during a three-year period. Determinants of MDR as compared with non-MDR microbial aetiology and impact of MDR versus non-MDR aetiology on mortality were investigated using multivariate logistic and competing risk regression analysis. Results MDR pathogens were involved in 52 of 192 episodes of VAP (27%): methicillin-resistant Staphylococcus aureus in 12 (6%), extended-spectrum beta-lactamase producing Enterobacteriaceae in 28 (15%), MDR Pseudomonas aeruginosa and other non-fermenting pathogens in 12 (6%). Multivariable logistic regression identified the Charlson index of comorbidity (odds ratio (OR) = 1.38, 95% confidence interval (CI) = 1.08 to 1.75, p = 0.01) and previous exposure to more than two different antibiotic classes (OR = 5.11, 95% CI = 1.38 to 18.89, p = 0.01) as predictors of MDR aetiology. Thirty-day mortality after VAP diagnosis caused by MDR versus non-MDR was 37% and 20% (p = 0.02), respectively. A multivariate competing risk regression analysis showed that renal replacement therapy before VAP (standardised hazard ratio (SHR) = 2.69, 95% CI = 1.47 to 4.94, p = 0.01), the Charlson index of comorbidity (SHR = 1.21, 95% CI = 1.03 to 1.41, p = 0.03) and septic shock on admission to the intensive care unit (SHR = 1.86, 95% CI = 1.03 to 3.35, p = 0.03), but not MDR aetiology of VAP, were independent predictors of mortality. Conclusions The risk of MDR pathogens causing VAP was mainly determined by comorbidity and prior exposure to more than two antibiotics. The increased mortality of VAP caused by MDR as compared with non-MDR pathogens was explained by more severe comorbidity and organ failure before VAP