The Effect of Silica Surface Area on Microparticle Retention Systems

Retention of fines and fillers has always been a concern in the paper industry. There has been many different types of retention aids in the past, but they lack performance under the vigorous conditions in today\u27s paper mills. High shear forces associated with high speed paper of recycled materials into the mill brought along with it high fines content and a lot of anionic trash which readily reacts with cationic polymers. Consequently, the dosage must be increased which can lead to poor formation and increased chemical cost. A new retention aid was needed to combat these problems. Microparticle retention systems were developed by a group of papermakers, scientist, and process control experts in the late 1970\u27s. A dramatic improvement in retention and drainage was achieved, which allowed higher filler loading, increased machine speeds, and better formation. To this date, continuing research is being done on the improvement of microparticle retention aids as well as developing new retention aids. This paper deals with microparticle retention systems in a different way. Normally, the dosage of microparticle, anionic silica in this research, to the system is on a weight basis, i.e., pounds of microparticle per ton of paper. In this study, silica dosage will be done on a surface area basis. Silica particles have a very high specific surface area, which can range anywhere from around 500m2/g to 1200m2/g. Using this information and the typical dosage rate on a weight basis, a surface area dosage can be calculated. For example, 600m2/g X 1.0 lb./ton = 272,155m2/ton and 1200m2/g X 0.5lb./ton X 272,155m2/ton . Both give the same surface area dosage, but different only half of the weight basis dosage is needed for the high surface area silica. Therefore, the objective of this thesis is to test the hypothesis that equivalent retention will be obtained when equal surface area dosage is applied to the system. A two level, three variable factorial design was used to test the effects of surface area of microparticle, surface area dosage, and polymer dosage. Two different furnishes were used, a fine paper grade and a wood containing grade. Both grades are similar to those found in industry. All retention studies were carried out using a Britt Dynamic Drainage Jar. Percent fines and ash retention was measured. The results for the fine paper furnish showed no conclusive trends other than an effect of polymer dosage on fines retention. The variability in the system was extremely high. The wood containing furnish, however showed several promising results. Again, the polymer dosage was found to have a large effect on the system. There was an interaction between surface area dosage and polymer dosage. At low polymer dosages, the surface area dosage had an effect on retention, but at high polymer dosage, there was not an improved retention response as the surface area dosage increased. Finally, the wood containing furnish followed the hypothesis that equivalent retention will be obtained at equal surface area dosage. Many chemical suppliers pride themselves on the high surface area of their microparticle and the improved performance it offers. The results of this thesis show that this may not be exactly true. The dosage needed to get the same retention with a high surface area microparticle may be less, but not necessarily improved performance. If retention could be measured as a function of surface area added to the system per ton of paper, a mill could determine what is the most economical microparticle to use. For example, a supplier could supply a low surface area microparticle at a very low price, while the another supplier is offering a high surface area microparticle at an extremely high price. The mill would have to use a lot more of the low surface area microparticle to get the retention they want, but it sill may be more economical

From those lying facts to the underlying deficit

Developments in the headline budget balance are distorted by temporary factors. The most significant of these factors are the business cycle and creative accounting. Adequate information and estimates are available, allowing us to filter out these factors using a so-called adjustment for self-reversal. Expenditures and revenues adjusted in this way, however, continue to fluctuate, as fiscal policy measures can, in part, also turn out to be temporary in retrospect. We filter out this effect by using a four-year moving average (covering a full election cycle), instead of taking individual pieces of information into account. Moving averages are calculated in a forward-looking manner, for the three subsequent years in addition to the current year. This allows temporary effects in the past to be captured and renders their identification easier over the forecast horizon. Based on our results, the deficit indicators obtained using the adjustment for self-reversal and the adjustment for policy reversal are similar; the latter method, however, yields a higher deficit for the period 2010–2012, due to the tax cuts (phasing out of temporary taxes) announced for 2013. Overall, however, both adjusted indicators deviate substantially from the headline indicator, highlighting the significance of the adjustment.structural deficit, underlying deficit, cyclical adjustment, temporary measures, creative accounting

Designable buried waveguides in sapphire by proton implantation

Buried and stacked planar as well as buried single and parallel channel waveguides are fabricated in sapphire by proton implantation. Good control of the implantation parameters provides excellent confinement of the guided light in each structure. Low propagation losses are obtained in fundamental-mode, buried channel waveguides without postimplantation annealing. Choice of the implantation parameters allows one to design mode shapes with different ellipticity and/or mode asymmetry in each orthogonal direction, thus demonstrating the versatility of the fabrication method. Horizontal and vertical parallelization is demonstrated for the design of one- or two-dimensional waveguide arrays in hard crystalline materials

Stochastic analysis of ocean wave states with and without rogue waves

This work presents an analysis of ocean wave data including rogue waves. A stochastic approach based on the theory of Markov processes is applied. With this analysis we achieve a characterization of the scale dependent complexity of ocean waves by means of a Fokker-Planck equation, providing stochastic information of multi-scale processes. In particular we show evidence of Markov properties for increment processes, which means that a three point closure for the complexity of the wave structures seems to be valid. Furthermore we estimate the parameters of the Fokker-Planck equation by parameter-free data analysis. The resulting Fokker-Planck equations are verified by numerical reconstruction. This work presents a new approach where the coherent structure of rogue waves seems to be integrated into the fundamental statistics of complex wave states.Comment: 18 pages, 13 figure

Poor description of non-pharmacological interventions:Analysis of consecutive sample of randomised trials

Objectives To evaluate the completeness of descriptions of non-pharmacological interventions in randomised trials, identify which elements are most frequently missing, and assess whether authors can provide missing details. Design Analysis of consecutive sample of randomised trials of non-pharmacological interventions. Data sources and study selection All reports of randomised trials of non-pharmacological interventions published in 2009 in six leading general medical journals; 133 trial reports, with 137 interventions, met the inclusion criteria. Data collection Using an eight item checklist, two raters assessed the primary full trial report, plus any reference materials, appendices, or websites. Questions about missing details were emailed to corresponding authors, and relevant items were then reassessed. Results Of 137 interventions, only 53 (39%) were adequately described; this was increased to 81 (59%) by using 63 responses from 88 contacted authors. The most frequently missing item was the “intervention materials” (47% complete), but it also improved the most after author response (92% complete). Whereas some authors (27/70) provided materials or further information, other authors (21/70) could not; their reasons included copyright or intellectual property concerns, not having the materials or intervention details, or being unaware of their importance. Although 46 (34%) trial interventions had further information or materials readily available on a website, many were not mentioned in the report, were not freely accessible, or the URL was no longer functioning. Conclusions Missing essential information about interventions is a frequent, yet remediable, contributor to the worldwide waste in research funding. If trial reports do not have a sufficient description of interventions, other researchers cannot build on the findings, and clinicians and patients cannot reliably implement useful interventions. Improvement will require action by funders, researchers, and publishers, aided by long term repositories of materials linked to publications

Structuring of sapphire by laser-assisted methods, ion-beam implantation, and chemical wet etching

Sapphire is an attractive material for micro- and opto-electronic systems applications because of its excellent mechanical and chemical properties. However, because of its hardness, sapphire is difficult to machine. Titanium-doped sapphire is a well-known broadly tunable and short-pulse laser material and a promising broadband light source for applications in low-coherence interferometry. We investigated several methods to fabricate rib structures in sapphire that can induce channel waveguiding in Ti:sapphire planar waveguides. These methods include direct laser ablation, laser-micromachined polyimide stripes, selective reactive ion etching, and ion-beam implantation followed by chemical wet etching. Depending on the method, we fabricated channels with depths of up to 1.5 µm. We will discuss and compare these methods. Reactive ion etching through laser-structured polyimide contact-masks has so far provided the best results in terms of etching speed and roughness of the etched structures