Development of a thulium (Tm:YAP) laser system for brain tissue ablation

In this study, a thulium (Tm:YAP) laser system was developed for brain surgery applications. As the Tm:YAP laser is a continuous-wave laser delivered via silica fibers, it would have great potential for stereotaxic neurosurgery with highest local absorption in the IR region. The laser system developed in this study allowed the user to set the power level, exposure time, and modulation parameters (pulse width and on-off cycles). The Tm:YAP laser beam (200-600 mW, 69-208 W/cm 2) was delivered from a distance of 2 mm to cortical and subcortical regions of ex-vivo Wistar rat brain tissue samples via a 200-μm-core optical fiber. The system performance, dosimetry study, and ablation characteristics of the Tm:YAP laser were tested at different power levels by maximizing the therapeutic effects and minimizing unwanted thermal side-effects. The coagulation and ablation diameters were measured under microscope. The maximum ablation efficiency (100 × ablation diameter/coagulation diameter) was obtained when the Tm:YAP laser system was operated at 200 mW for 10 s. At this laser dose, the ablation efficiency was found to be 71.4% and 58.7% for cortical and subcortical regions, respectively. The fiber-coupled Tm:YAP laser system in hence proposed for the delivery of photothermal therapies in medical applications. © 2011 Springer-Verlag London Ltd

Determination of environmental factors and indicator plant species for site suitability assessment of Crimean Juniper in the Acipayam District, Turkey

The present study was carried out to find the environmental and biotic indicators for site suitability of Crimean juniper (Juniperus excelsa L.) in the Acıpayam district, Turkey. Data were collected from 100 sample plots. Environmental variables (elevation, slope, radiation index, topographical position, landform characteristics and parent material) and plant species were recorded at each sample plot. Generalised addictive model (GAM) and indicator species analysis (ISA) were applied in order to model the distribution of Crimean juniper and determine the indicator species within its range. The results of the applied GAM analysis and the distribution model obtained showed that most suitable sites for the occurrence of Crimean juniper are the areas in the higher zones (supra and mountain Mediterranean zones) covered by limestone. The results obtained from indicator species analysis (ISA) confirmed the applied GAM results, in the sense that thermo-Mediterranean plant species such as Arbutus andrachne, Cercis siliquastrum, Cotinus coggyria, Pistacia terebinthus and Styrax officinalis are the negative indicator plant species for Crimean juniper while its positive associates from supra- and mountain-Mediterranean elements are Berberis crataegiana, Lonicera etrusca var. etrusca, Juniperus feoettidissima and Phlomis armeniaca. These findings are crucial to predict the suitable sites for the utilization of Crimean juniper in afforestration efforts by field managers in degraded and forestless areas of the Acipayam district

Effect of chip mixing ratio of Pinus pinaster and Populus tremula on kraft pulp and paper properties

In this study, Pinus pinaster and Populus tremula chip mixtures were kraft cooked and resulting pulp and paper properties were investigated. The chemical properties and fiber morphology of both species were examined. Cooks were made for five different pine/aspen chip mixtures (0, 25, 50, 75, and 100%). Results of this study showed that pulps with higher kappa number, viscosity, and reject ratio were observed for chips mixtures with higher pine ratio. Higher pine in the mixture resulted in lower total and screened yield. Increase in poplar ratio in mixture gave pulps that were easier to beat. Pine chips improved the strength properties and lowered the brightness and smoothness. © 2013 American Chemical Society

Improving strength properties of recycled and virgin pulp mixtures with dry strength agents

In the paper industry, the increasing use of recycled fibers as a substitute for virgin fibers has resulted in decreased strength properties. In this study, old corrugated container fibers were added in different ratios to virgin kraft fibers, and the effects on paper properties were investigated. Furthermore, 0.75% cationic starch and 0.75% Luredur® with respect to oven-dry fibers were added separately to old corrugated container fiber-containing/fiber-free suspensions, and the effects on handsheet strength properties were determined. Starch is the oldest and most common additive for improving the strength of paper. Luredur®, a cationic polymer-based vinyl amine and N-vinylformamide, is used for the same purpose in papermaking. Results indicated that, except for the tear index, old corrugated container fiber addition decreased handsheet strength properties in the agent-free samples. The cationic starch addition was more efficient than the Luredur® with regard to tensile index, stretch, tensile energy absorption, and burst index. However, the effect of Luredur® on the tear index was more pronounced compared to that of the cationic starch. Consequently, comparable handsheets strength was achieved in the 100% virgin and dry strength additive-free fibers with the addition of 0.75% cationic starch to a suspension containing 20% old corrugated containers and 80% virgin fiber. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

The effect of old corrugated container (OCC) pulp addition on the properties of paper made with virgin softwood kraft pulps

In this study, old corrugated container (OCC) pulp was added in different ratios (5%, 10%, 15%, 20%, and 25% w/w) to unbleached virgin pulps of both European black pine and Scots pine, and its effects on paper properties were investigated. As a control, OCC pulp-free handsheets were separately produced from European black pine and Scots pine pulps. The results indicated that the addition of OCC pulp decreased the strength properties, except for the tear index, of the handsheets. In addition, compared to the control handsheets, the paper containing the OCC pulp displayed higher air permeability. The results showed that up to 10% of the virgin softwood kraft pulp could be replaced with OCC pulp without bringing about considerable loss of strength. Also, this ratio of OCC addition could be suitable for production of wrapping papers

Biokraft pulping of European black pine with Ceriporiopsis subvermispora

European black pine (Pinus nigra Arn.) chips were treated with the white-rot fungus Ceriporiopsis subvermispora for periods ranging from 20 to 100 days. The effects of pretreatment on the chemical composition of wood and kraft pulping were investigated. The results showed that fungal pretreatment reduced the lignin and extractive content of wood chips. Also, weight losses occurred. Kappa number, viscosity, and reject ratio of biokraft pulps decreased. Biokraft pulps gave better response to beating, which led to significant energy saving during refining. The tear index, burst index, and tensile index of biokraft pulps were found to be lower than those of kraft pulps. However, the tensile index and burst index of 20-day biotreated and unbeaten pulp was higher than those of kraft pulp. Also, the tear index of 20-day biotreated and beaten pulp was higher than that of kraft pulp. The brightness of biokraft pulps decreased irregularly with increasing incubation time. © 2011 Elsevier Ltd