The alteration degree of the metacrystalline rocks based on UAI,Bolu (Turkey)

The geomechanical properties of the metacrystalline rock masses vary due to alteration. The Devonian aged Yedigoller formation crops out in the Asarsuyu valley (Bolu, Turkey). The aim of this study is to investigate the alteration degree of the amphibolite and metagranodiorites based on their geomechanical and petrographical properties. The P-wave velocity is 1,613–5,588 m/s and the unconfined compressive strength varies between 12.75 and 99.86 MPa. Several weathering products occurred due to carbonisation, oxidation and sericitation. These rocks, subjected to hydrothermal effects, are classified as “fresh” to “completely altered” according to the unified alteration index (UAI). In addition, the values of the loss on ignition, modified weathering potential index and chemical index of alteration were taken into account for supporting the alteration process. Since the main process is hydrothermal alteration, the rocks which were exposed to alteration are weathered on the slopes after excavation. Weathering classification and the chemical indices indicate this process. Thus, UAI is concluded to be more suitable and credible in order to evaluate the hydrothermal alteration process of such crystalline rocks numerically.     

Structural and Magnetic Properties of One-Dimensional Squarate Bridged Coordination Polymers Containing 2-Aminomethylpyridine Ligand

Three novel one-dimensional (1D) coordination polymers with general formula {[M(μ-sq)₂(amp)₂]·H₂O}_n [M=Cu(II) (1), Zn(II) (2)] and [Cd(μ-sq)₂(amp)₂]_n (3) [sq: Squarate; amp:2-aminomethylpyridine] have been prepared and spectroscopically studied. Each metal (II) ion in 1–3 is octahedrally coordinated by two sq and two amp ligands. The amp ligands are N,N′ coordinated, while the sq ligands bridge the metal centers forming 1D linear chain structure. The individual chains are linked by O–H···O hydrogen bonds involving the hydrogens of water molecules (1–2), amino hydrogens and squarate O atoms (1–3). The hydrogen bonded layers are further assembled into three-dimensional supramolecular networks by weak aromatic π–π interactions. EPR results indicate that the ground state of the paramagnetic electron in 1 and Cu²⁺ doped complexes 2–3 is d_{x² - y²} d_{{x^{2} - y^{2} }} . Magnetic measurements reveal that complex 1 shows paramagnetic behavior.     

Preparation and characterization of phosphine oxide based polyurethane/silica nanocomposite via non-isocyanate route

A novel carbonate-modified bis(4-glycidyloxy phenyl) phenyl phosphine oxide (CBGPPO) was synthesized to prepare phosphine oxide based polyurethane/silica nanocomposites. Spherical silica particles were prepared according to Stöber method and modified with cyclic carbonate functional silane coupling agent (CPS) to improve the compatibility of silica particles and organic phase. The cyclic carbonate-modified epoxy resins and silica particles were used to prepare hybrid coatings using hexamethylene diamine as a curing agent. The cupping, impact and gloss measurements were performed on aluminum panels, and the tensile test, gel content, thermal and morphological analyses were conducted on the free films. No damage was observed in the impact strength of the coatings. Incorporation of silica and CBGPPO into formulations increased modulus and hardness of the coating making the material more brittle. It was also observed that, the thermal stability of hybrid coatings enhanced with the addition of silica and CBGPPO.     

Effect of Brood Pheromone on Survival and Nutrient Intake of African Honey Bees (<Emphasis Type=Italic>Apis mellifera scutellata</Emphasis>) under Controlled Conditions

The influence of pheromones on insect physiology and behavior has been thoroughly reported for numerous aspects, such as attraction, gland development, aggregation, mate and kin recognition. Brood pheromone (BP) is released by honey bee larvae to indicate their protein requirements to the colony. Although BP is known to modulate pollen and protein consumption, which in turn can affect physiological and morphological parameters, such as hypopharyngeal gland (HPG) development and ovarian activation, few studies have focused on the effect of BP on nutritional balance. In this study, we exposed newly emerged worker bees for 14 d and found that BP exposure increased protein intake during the first few days, with a peak in consumption at day four following exposure. BP exposure decreased survival of caged honey bees, but did not affect either the size of the HPG acini or ovarian activation stage. The uncoupling of the BP releaser effect, facilitated by working under controlled conditions, and the presence of larvae as stimulating cues are discussed.     

Synthesis of conducting polysiloxane — polypyrrole graft copolymers

Summary Polysiloxane-polypyrrole graft copolymers have been synthesized by a series of chemical reactions and subsequent electropolymerization. First, the hydrosilation of 4-vinyl aniline by dimethyl-methylhydrosiloxane copolymer gave the corresponding aminophenyl functional polydimethylsiloxane (PDMS-NH₂). The side chain pyrrole functionalized polysiloxanes were then prepared by the reaction of PDMS-NH₂ with glycidylpyrrole. Finally, the synthesis of graft copolymers of polysiloxane and pyrrole has been achieved electrochemically by using two different electrolytes, p-toluene sulfonic acid (PTSA) and tetrabutylammonium tetrafluoroborate (TBAFB). Characterization of these graft copolymers were performed by a combination of techniques consisting of scanning electron microscopy (SEM), thermal gravimetry (TGA), differential scanning calorimetry (DSC) analyses and FT-IR studies. The conductivities were measured by four-probe technique. Received: 19 September 2001/ Revised version: 4 December 2001/ Accepted: 2 December 2001     

Effect of 2D WS<Subscript>2</Subscript> Addition on Cold-Sprayed Aluminum Coating

Tungsten disulfide (WS₂) has excellent solid lubrication properties due to its 2D layered structure. This study focuses on depositing Al-2 wt.% WS₂ composite coating by cold spray technique. The effect of WS₂ addition on the microstructure, mechanical and tribological properties of the composite coatings is examined in the as-deposited and heat-treated conditions. After heat treatment, the coating density increased to 99% with improved intersplat bonding. The microhardness of the heat-treated Al-2 wt.% WS₂ coating increased by 56% as compared to the as-sprayed coating. The wear resistance of heat-treated Al-2 wt.% WS₂ coating improved by 75% with a synergistic reduction in the coefficient of friction (COF) by 51%. Transmission electron microscopy investigation reveals the presence of layered WS₂ within aluminum splats with a strong interface. This study shows that cold spraying can be effectively used to integrate 2D layered WS₂ as a solid lubricant in the metallic coatings.     

Investigation of kinetics of borided ductile and lamellar graphite cast iron

In this study, kinetics of borided ductile iron and lameller graphite grey cast iron were investigated by processing boronizing treatment (was carried out in Ekobor-II powders). The process temperatures and durations respectively 1123, 1173, 1223 K for 2, 4 and 6 hours, with pack boronizing method and under atmospheric pressure in electrical resistance furnace. Changing of borided layer properties was investigated by using optical and scanning electron microscopy, X-ray diffraction and micro-Vickers hardness testers. The growth kinetics of the boride layers forming and thickness of boride layer were computed for both cast iron. The main phases for two processes Fe₂B and FeB were defined on the surface.     

Conducting Copolymers of 3-Methylthienyl Methacrylate and p-Vinylbenzyloxy Poly(ethyleneoxide) and Their Electrochromic Properties

Summary A random copolymer (CP) containing 3-methylthienyl methacrylate (MTM) and p-vinylbenzyloxy poly(ethyleneoxide) (PEO-VB) units was synthesized. Further graft copolymerization of CP with pyrrole (Py) and thiophene (Th) were achieved in H₂O - sodium dodecyl sulfate (SDS), H₂O - p-toluenesulphonic acid (PTSA) and acetonitrile (AN) - tetrabutylammonium tetrafluoroborate (TBAFB) solvent electrolyte couples via constant potential electrolyses. Characterization was performed by cyclic voltammetry (CV), nuclear magnetic resonance spectroscopy (NMR), and fourier transform infrared spectroscopy (FTIR). The morphologies of the films were examined by scanning electron microscopy (SEM). Conductivities of the samples were measured by using four-probe technique. Moreover, spectroelectrochemical and electrochromic properties of the copolymer obtained from thiophene were investigated by UV-Vis spectrometry and colorimetry.