NITROGEN SOURCES IN ADIRONDACK WETLANDS DOMINATED BY NITROGEN-FIXING SHRUBS

Abstract: In the Adirondack region of northern New York, USA, Alnus incana ssp. rugosa and Myrica gale often dominate wetland shrub communities and fix nitrogen in symbiosis with actinomycetes of the genus Frankia. The objective of this study was to examine the contribution of these shrubs to the N economies of whole wetlands in the Adirondacks where N has been considered a potential pollutant and contributor to low acid-neutralizing capacity, and where N deposition may reduce rates of nitrogen fixation in actinorhizal plants. Nitrogen chemistry of plant foliage was examined, and density and foliar biomass of nitrogen fixing shrubs were estimated in plots or belt transects in six shrub wetlands near atmospheric deposition monitoring stations in order to estimate the fraction of N derived from fixation in A. incana ssp. rugosa and M. gale tissues. Lake-inlet-wetlands were dominated by alder that derives Ն85% foliar N from fixation, but M. gale was most abundant in lake outlet wetlands and seemed to rely less on fixed N, although results for Myrica were more uncertain. Substantial N is therefore added to lake inlet systems dominated by alder (7-18 kg ha Ϫ1 yr Ϫ1 ), while N fixed from M. gale does not appear to exceed 3 kg ha Ϫ1 yr Ϫ1 , except in localized patches at smaller spatial scales. Similarity in ␦ 15 N between non-fixing field shrubs and reference values for fixed N at some sites suggests that fixed N is being recycled in the plant community. Wet atmospheric N deposition is 3-6 kg ha Ϫ1 yr Ϫ1 and does not decrease N fixation substantially in alder. Overall, shrubs in wetlands dominated by these actinorhizal N 2 -fixing plants are not taking up substantial quantities of anthropogenic N, suggesting that nitrogen is processed microbially or transferred along with some fixed N to downstream ecosystems

The effects of cutting tool geometry and processing parameters on the surface roughness of AISI 1030 steel

In this study, we have investigated the effects of different insert radii of cutting tools, different depths of cut and, different feed rates on the surface quality of the workpieces depending on various processing parameters. Properly, the AISI 1030 steel is processed at a digitally controlled computerised numerical control(CNC) turning lathe without using cooling water with three different insert radii (0.4, 0.8, and 1.2 mm) of cemented carbide cutting tools, coated with three layer coating materials (outermost is TiN) applied by the chemical vapour deposition CVD technique. The effects of five different depths of cut (0.5, 1, 1.5, 2, 2.5 mm) and five different feed rates/advancing steps (0.15, 0.2, 0.25, 0.30, 0.35 mm/rev) on the surface roughness values have been investigated by a turning process while from the cutting parameters the cutting speed is kept constant at (300 m/min). It is seen that the insert radius, feed rate, and depth of cut have different effects on the surface roughness. In the experiments, the minimum average surface roughness has been obtained using the cutting tools of maximum insert radius (1.2 mm). The surface roughness have been improved by 293% when the insert radius (0.4 mm) was increased by 200% (1.2 mm). When the feed rate (0.35 mm/rev) was reduced by 133% (0.15 mm/rev), the surface roughness have been improved by 313%, and by reducing the depth of cut (0.5 mm) by 400% (0.25 mm), an amelioration of 23% has been obtained on the surface roughness. © 2005 Elsevier Ltd. All rights reserved

The effects of cutting tool coatings on the surface roughness of AISI 1015 steel depending on cutting parameters

The effects of a number of cutting tool coating materials on the surface quality of workpieces, depending on various cutting parameters, were investigated. AISI 1015 steel was processed without cooling on a lathe using 4 different cemented carbide cutting tools, i.e. uncoated, coated with AlTiN and coated with TiAlN using the PVD technique, and one with 3-layer coatings (outermost being TiN) applied by the CVD technique. Among the cutting parameters, the depth of cut was kept constant (2.5 mm) while the cutting speed and feed rate were changed. Five cutting speeds (50, 73, 102, 145, 205 m/min) and 2 feed rates (0.24 and 0.32 mm/ rev) were used during the machining process. Coating type, feed rate and cutting speed have different effects on surface roughness. In the experiments, less average surface roughness was obtained by using a 3-layer coated tool coated outermost with TiN. The lessening of cutting speed by about 33% improves the surface roughness by about 26% increasing the cutting speed by about 310% resulted in an improvement of about 69%. cr Tübitak

Shear bond strength of a novel porcelain repair system for different computer‑aided design/computer‑assisted manufacturing ceramic materials

Objectives: The purpose of this study was to compare the shear bond strength of a novel repair system, Nova Compo SF with Ceramic Repair, Ivoclar, to computer‑aided design/computer‑assisted manufacturing (CAD/CAM) restorative materials (IPS e.max CAD and Empress CAD). Materials and Methods: The specimens of each CAD/CAM restorative material were randomly divided into two subgroups of nine specimens, using one of two repair systems. All specimens were etched with hydrofluoric acid and rinsed under a water spray for 10 s, then air‑dried for 10 s. Next, repair systems were applied according to the manufacturer’s instructions. All specimens were stored in distilled water at 37°C for 24 h and then additionally aged for 5000 thermal cycles. A shear bond strength test was performed using a universal testing machine. Each fracture type was examined under a stereomicroscope at ×12.5 magnification. A two‑way ANOVA test was used to detect significant differences between the CAD/CAM restorative materials and the composite repair systems. Subgroup analyses were performed using Tukey’s honest significant difference. Results: No statistically significant differences were observed between the repair systems (P = 0.9). The bond strength values from Empress CAD were statistically higher than those from e.max CAD (P ˂ 0.05).Conclusions: Within limitations, SuperFlow may be an alternative to the ceramic repair materials we routinely used in the clinic. Empress CAD can be preferable to e.max CAD in terms of esthetically suitable clinical indications.Keywords: Bond strength, computer‑aided design/computer‑assisted manufacturing, porcelain, repair syste

Byaz kiraz meyvesi (Starks gold) polifenol oksidazının karakterizasyonu

Beyaz kiraz meyvesinden (starks gold) polifenol oksidaz enzimi ekstrakte edilmiş ve amonyum sülfat çökeltmesi, diyaliz ve iyon değişim kromatoğrafisi ile saflaştırılmıştır. Toyopearl 650 M kolon kromatoğrafisi sonucunda PFO aktivitesi gösteren izoenzim A ve izoenzim B ile belirtilmiş iki pik elde edilmiştir. İzoenzim A % 34.9 verimle 3-9 kat, izoenzim B % 54.3 verimle 76.7 kat saflaştırılmıştır. İzoenziriı A ve B'nin optimum pH değerleri sırası ile 4.5 ve 4.98 olarak bulunmuştur. Optimum sıcaklık değerinin izoenzim A için 20 °C ve izoenzim B için 30 °C olduğu saptanmıştır. İzoenzim B'nin kateşol substratına ilgisi izoenzim B'den daha yüksektir. Aktivasyon enerjisi ve Z değerleri izoenzim A için 22.1 °C (r2= 0.883) ve 98.5 kj/mol (r2= 0.878), izoenzim B için. 13.9 °C (r2= 0.990) ve 157.1 kj/mol (r2= 0.989) bulunmuştur. L-sistein ve sodyum disülfitin inhibitor etkisinin birbirinden farklı olduğu belirlenmiştir.Polyphenol oxidase (PPO) from white cherry fruit (starks gold) was extracted and purified through (NH4)2S04 precipitation, dialysis and ion exchange chromatography. The enzyme showed two peaks with PPO activity on Toyopearl 650 M column, which were denoted as isoenzyme A and isoenzyme B. A 3-9 fold purification of isoenzyme A with a recovery of 34.9 % and 76.7 fold purification of isoenzyme B with a recovery of 54.3 % were achieved. pH optima of isoenzyme A and B were 4.5 and 4.98, respectively. The temperature optima for enzyme activity were found to be 20 °C for isoenzyme A and 30°C for isoenzyme B. The affinity of isoenzyme B for catechol as substrate was higher than that of isoenzyme A. Activation energies and Z values were found to be 22.1°C (r2= 0.883) and 98.5 kj/mol (r2= 0.878) for isoenzyme A and 13-9 °C (r2= 0.990) and 157.1 kj/mol (r2= 0.989) for isoenzyme B, respectively. Inhibitory effect of L-cysteine and sodium disulphide differed from each other

The experimental investigation of the effects of uncoated, PVD- and CVD-coated cemented carbide inserts and cutting parameters on surface roughness in CNC turning and its prediction using artificial neural networks

In this study the machining of AISI 1030 steel (i.e. orthogonal cutting) uncoated, PVD- and CVD-coated cemented carbide insert with different feed rates of 0.25, 0.30, 0.35, 0.40 and 0.45 mm/rev with the cutting speeds of 100, 200 and 300 m/min by keeping depth of cuts constant (i.e. 2 mm), without using cooling liquids has been accomplished. The surface roughness effects of coating method, coating material, cutting speed and feed rate on the workpiece have been investigated. Among the cutting tools-with 200 mm/min cutting speed and 0.25 mm/rev feed rate-the TiN coated with PVD method has provided 2.16 µm, TiAlN coated with PVD method has provided 2.3 µm, AlTiN coated with PVD method has provided 2.46 µm surface roughness values, respectively. While the uncoated cutting tool with the cutting speed of 100 m/min and 0.25 mm/rev feed rate has yielded the surface roughness value of 2.45 µm. Afterwards, these experimental studies were executed on artificial neural networks (ANN). The training and test data of the ANNs have been prepared using experimental patterns for the surface roughness. In the input layer of the ANNs, the coating tools, feed rate (f) and cutting speed (V) values are used while at the output layer the surface roughness values are used. They are used to train and test multilayered, hierarchically connected and directed networks with varying numbers of the hidden layers using back-propagation scaled conjugate gradient (SCG) and Levenberg-Marquardt (LM) algorithms with the logistic sigmoid transfer function. The experimental values and ANN predictions are compared by statistical error analyzing methods. It is shown that the SCG model with nine neurons in the hidden layer has produced absolute fraction of variance (R2) values about 0.99985 for the training data, and 0.99983 for the test data; root mean square error (RMSE) values are smaller than 0.00265; and mean error percentage (MEP) are about 1.13458 and 1.88698 for the training and test data, respectively. Therefore, the surface roughness value has been determined by the ANN with an acceptable accuracy. © 2008 Elsevier Ltd. All rights reserved

Hydrothermal gasification of poplar wood chips with alkali, mineral, and metal impregnated activated carbon catalysts

In this study, poplar wood chips were gasified in sub-and supercritical water as biomass feedstock. Hydrothermal gasification experiments were performed to examine how the reaction temperature and different type of catalysts influence conversion efficiency. The effectiveness of commercially available [alkali catalyst; KOH], naturally available [mineral catalysts; Trona [Na3(CO3)(HCO3)·2H2O], Dolomite [CaMg(CO3)2] and Borax [Na2B4O7·10H2O] and laboratory-prepared catalysts [metal-impregnated activated carbons; (Ni/AC) and (Ru/AC)] have been demonstrated so as to shift the product distribution toward more desirable compounds. Gaseous compound yield was increased from 29.7% to 79.3% with respect to increasing temperature while liquid compound yield decreased from 27.6% to 1.1% and solid residue from 38.0% to 15.6%. The highest H2 (20.1 mol/kg C in poplar) and CH4 (12.7 mol/kg C in poplar) yields were obtained with Ru/AC catalyst. Carboxylic acids and 5-methyl furfural were determined as the main liquid compounds. © 2019 Elsevier B.V.109M284 Türkiye Bilimsel ve Teknolojik Araştirma KurumuWe gratefully acknowledge the financial support for this work provided by the Scientific and Technological Research Council of Turkey (TUBITAK) (Research Project No: 109M284). -