Crystallization of polyethylene under low gravity conditions: Implications for continued microgravity research on polymers

Linear polyethylene is a macromolecular system well suited for microgravity research; it has neither steric hindrances, sidegroups, polar moieties nor toxicity constraints peculiar to many organic systems. This research has centered upon determination of the effects of convection on the solidification of non-Newtonian fluid systems. Initial research served to identify the viability of polymer systems for low gravity processing affects. These investigations served to resolve gravity-induced variations in both solidified thickness and nucleation sites for thin (10 micron) melt/solidified polyethylene samples. Further, a variation in the birefringence of the solidified sample, correlatable to solidification gravity conditions but independent of nucleation sites or solidification thickness, demonstrated that morphological variations occurred during solidification that were resultant of gravitational fields. To investigate these minute effects a furnace was designed and fabricated and flown on the NASA microgravity aircraft: KC-135. The significant features of the furnace were the directional solidification aspects (eliminating gravity induced nucleation site variations), translation of the sample at its growth rate (allowing optical interface monitoring and reducing secondary nucleation concerns) and use of monitoring equipment (thermal, interferometric, acceleration and microscopy). Rheometric Dynamic Spectroscopy (RDS) was used to define the non-Newtonian nature of the polyethylene. The flight results were reviewed and hundreds of frames of interferometry data were reduced, and calibrated against thermocouple and accelerometer results. Analysis, using a computational fluid dynamics code was performed. A comparison of predicted results to empirical data for thermal gradients, flow velocities and crystallization conditions, assuming two gravitational conditions (10\sp{-4} and 1 g- level) and two viscosity assumptions (no shear thinning and with RDS data shear thinning) was performed. The results from these studies show that the pursuit of microgravity crystallization of polymer systems is both viable and warranted assuming appropriate experimental goals and analytical tools. Specific test results indicate that gravitational forces are correlatable to thermal variations during solidification, and these variations appear correlatable to post crystallization morphology. Further, analyses of non-Newtonian fluid system crystallization processes must include viscoelastic assumptions

Bolu Abant İzzet Baysal Üniversitesi Araştırma Alanları Topraklarının Bazı Fiziksel ve Kimyasal Özelliklerinin Belirlenmesi

Bu çalışmada Bolu Abant İzzet Baysal Üniversitesine ait Araştırma ve Deneme alanı topraklarının bazı fiziksel ve kimyasal özellikleri ile besin elementi içeriklerinin belirlenmesi amaçlanmıştır. Çalışma alanında 0-20 cm ve 20-40 cm derinlikten alınan 30 adet toprak örneğinde yapılan analizler sonucunda toprakların büyük bir kısmının tınlı bünyeli olduğu, pH’larının hafif asidik ile hafif alkali arasında değiştiği, genel olarak tuzsuz, çok az kireçli ile çok fazla kireçli arasında kireç içeriklerine sahip oldukları tespit edilmiştir. Organik madde içeriklerinin yüzey toprak örneklerinde orta ve yeter seviyelerde olduğu belirlenmiştir. Toprakların yarayışlı fosfor ve alınabilir potasyum bakımından çok fazla sınıfında yer aldığı, mikro besin elementlerinden yarayışlı çinko içeriklerinin noksan, diğer mikro besin elementlerinin yeter ve fazla sınır değerleri içerinde yer aldıkları bulunmuştur

Effects of Nickel Contamination on Nutrient Contents of Daffodil (Narcissus poeticus L. c.v. “Ice Folies”)

The objective of this study was to determine the effects of nickel on nutrient contents of daffodil (Narcissus poeticus L. c.v. “Ice Folies”) in nickel contaminated media. This research was carried out in a completely randomized experimental design with three replications in greenhouse conditions.  Four different doses of nickel   (control, 25 mg kg-1, 50 mg kg-1, 75 mg kg-1) were applied to each pot having 500 g soil:sand mixture in  2:1 ratio. The distillate water was used in irrigation and ½  hoagland solution was applied for fertilization. At the end of experiment the highest K, Mg and Ca contents of daffodil bulbs were obtained as 0.90 %, 0.91 % and 2.72 % in control respectively. The highest Fe (27.42 mg kg-1), Cu (7.62 mg kg-1), and Zn (20.99 mg kg-1)  were in 50 mg kg-1, 75 mg kg-1 and 25 mg kg-1 nickel applications respectively. Similarly the highest K, Mg and Ca contents of daffodil leaves were obtained as 2.2 %, 1.72 % and 5.87 % in control.  The highest Fe contents (66.62 mg kg-1) was in 25 mg kg-1 nickel application, while Cu (41.29 mg kg-1) and Zn contents  (41.04 mg kg-1) were in 75 mg kg-1 nickel application. Nickel applications increased micronutrients contents of daffodils except manganese