HOUSING IN TURKEY - PROSPECTS FOR DIFFERENT INCOME GROUPS

It is imperative to develop a macro-level framework, and long-term policy alternatives to solve the housing problems of Turkey. Since most of the past housing programmes in Turkey were dependent on the estimation of housing needs, effective demand could not be properly evaluated. Yet, housing demand is closely connected with income level and ability to pay. So, effective housing programmes necessitate the predetermination of target groups, where income level and income share devoted to housing expenditures are considered. With this in mind, this study aims to compare alternative scenarios of housing finance considering their accessibility to different income groups. For this purpose, a macro-economic simulation model of housing needs assessment was utilised. Investment and subsidy requirements of the proposed housing programmes were also evaluated by using macro-economic data such as GDP growth rate, inflation and housing investment. As a result, it was concluded that current housing programmes are very far from meeting the demand of households. Comparison of four scenarios showed that new policy proposals should cover rental housing, especially for low income groups

An in depth study of the formation of new tetrathiafulvalene derivatives from 1,8-diketones

A detailed study of the reactions of phosphorus pentasulfide and Lawesson's reagent with a series of 4,5-bis(RCOCHS)-1,3-dithiole-2-thiones (R-Ph, 4-MeOC6H4, 4-Br C6H4, Me) has been carried out. These reactions lead to fusion of either an unsaturated 1,4-dithiin ring or a thiophene to the dithiole; the former in higher yield, while the latter is a significant product in the reactions with Lawesson's reagent; as well as small amounts of minor products. A mechanistic rationalization of these products is discussed in some detail. The new fused dithioles have been converted to novel series of fused TTF derivatives

Phenylene-2,5-dimethylpyrazine co-oligomers: synthesis by Suzuki couplings, X-ray structures of neutral and diprotonated teraryl species and efficient blue emission

Phenylene-2,5-dimethylpyrazinyl co-oligomers and a dipyridylpyrazine derivative have been synthesised by Suzuki cross-coupling reactions starting from 2,5-dibromo-3,6-dimethylpyrazine. X-Ray crystal structures are reported for two teraryl derivatives, viz. 2,5-bis(2-methoxyphenyl)-3,6-dimethylpyrazine 2 and 2,5-bis(6-methoxypyridin-3-yl)-3,6-dimethylpyrazine 6, and a diprotonated pyrazinyl dication salt, viz. 2,5-bis(2-methoxyphenyl)-3,6-dimethylpyrazinium bis(tetrafluoroborate) salt 3. Compounds 2 and 6 and the dication in 3 have crystallographic C-i symmetry and adopt twisted conformations: dihedral angles between the aryl and pyrazine rings are 74.0degrees (2), 56.4degrees (3) and 44.6degrees (6). Violet-blue photoluminescence is seen for 2 lambda(max) 372 nm, 5 lambda(max) 418 nm and 6 lambda(max) 387 nm in ethanol solution. [Compound 5 is 1,4-dimethoxy-2,5-bis{2-(5-tertbutylphenyl-3,6-dimethylpyrazinyl)benzene }]. Blue electroluminescence, lambda(max) 444 nm, is observed for the device structure ITO/PEDOT/5/Ca with no long-wavelength emission from pi-aggregates or exciton states

Synthesis and investigation of intra-molecular charge transfer state properties of novel donor-acceptor-donor pyridine derivatives: the effects of temperature and environment on molecular configurations and the origin of delayed fluorescence

A novel series of donor-acceptor-donor (D-A-D) structured pyridine derivatives were synthesised and detailed photo-physical investigations were made using mainly steady-state and time-resolved spectroscopy techniques at varying temperatures. The investigations showed that the molecules have solvent polarity and temperature dependent excited-state configurations, confirmed in two different polarity solvents (295-90 K), i.e. methyl cyclohexane (MCH) and 2-methyltetrahdrofurane (2-MeTHF). In MCH, the investigations revealed dual fluorescence over the temperature range of 295-90 K. At 295 K, the ground-state configuration of the molecules has a partially twisted geometry as determined by DFT calculation, yet the emission originates totally from a locally excited (LE) state, however once the temperature is lowered to 90 K, the twisted molecular configuration is stabilised, and the emission originates from a fully-relaxed intramolecular charge transfer state (ICT), this is contrary to the systems where structural reorganisation stabilises ICT and this is frozen out at low temperatures. The DFT calculations revealed different ground state molecular configurations due to the presence of different electron-donating groups, e.g. the molecule including anthracene groups has a near 901 twisted geometry whereas the triphenylamine including molecule has a pyramidal geometrical folding, therefore, the decrease in temperature restricts the donor degree of rotational freedom. In 2-MeTHF solution, the fluorescence spectrum of both molecules is always of ICT character, but gradually red-shifts through the fluid to glass transition temperature (B135 K), in this case, the fluorescence occurs after structural and solvent-shell relaxations, however, upon cooling below 135 K, the spectra dramatically shift back to blue giving rise to strong emission from an ICT excited-state (but not the LE state) where the molecules have unrelaxed geometries. This significant change in the nature of the emitting species was explained with specific solvent-solute dynamic interactions in the vicinity of the solvation shell and the effect of thermal excitation of molecular vibrational modes of the C-C bond linking donor and acceptor units. Finally, we confirmed that the molecules have ICT ground-state geometry in the solid-state phase (spin-coated films), and the time-resolved decay dynamics were investigated comparing the spin-coated films (at RT and 25 K) and MCH solutions (at 295 K and 90 K)

Impact of COPD exacerbation on cerebral blood flow

We aimed to investigate the impact of chronic obstructive pulmonary disease (COPD) exacerbation on cerebral blood flow (CBF). In 21 COPD patients - in both exacerbation and stable phases -Doppler ultrasonographies of internal carotid artery (ICA) and vertebral artery (VA) were performed. There were significant differences in total, anterior and posterior CBF, ICA and VA flow volumes in exacerbated COPD compared to stable COPD. Total CBF was correlated with cross-sectional areas of left and right ICA, whereas independent predictor of total CBF was cross-sectional area of right ICA. Increased CBF might indicate cerebral autoregulation-mediated vasodilatation to overcome COPD exacerbation induced hypoxia. © 2012 Elsevier Inc

2,5-di(aryleneethynyl)pyrazine derivatives: synthesis, structural and optoelectronic properties, and light-emitting device

A series of 2,5-di(aryleneethynyl) pyrazine derivatives has been synthesised in 23-41% yields by two-fold reaction of 2,5-dibromo-3,6-dimethylpyrazine 3 with ethynylarenes (arene=phenyl, 2-pyridyl, 4-ethylphenyl, 4-chlorophenyl, 4-biphenyl) under standard Sonogashira conditions [CuI, Pd(PPh3)(2)C(l)2, NEt3, THF]. Compound 3 has been converted into 2,5-diethynyl-3,6-dimethylpyrazine, which reacts with 2-iodothiophene to yield 2,5-bis(thien-2-ylethynyl)-3,6-dimethylpyrazine. In the X-ray crystal structure of 2,5-di(phenylethynyl)-3,6-dimethylpyrazine 4 the two phenyl rings are parallel and the pyrazine ring is inclined to their planes by 14.2degrees. Quantum chemical calculations establish that the HOMO-LUMO gap for 4 (3.56 eV) is lower than that of di(phenylethynyl) benzene 12 (3.72 eV). The nitrogen atoms of 4 serve to localise the HOMO on the central ring's carbon atoms, resulting in a quinoidal-type population, in contrast to 12. Cyclic voltammetric studies establish that 4 undergoes a reduction to the radical anion at ca. -1.9 V (vs. Ag/Ag+ in MeCN), which is almost reversible at high scan rates (500 mV s(-1)). The UV-vis absorption and photoluminescence profiles of 4 in cyclohexane are similar to those of 12; the emission for 4 (lambda(max) 379 and 395 nm) is red-shifted compared to 12. Single-layer OLEDs using MEH-PPV as the emissive polymer show significantly enhanced external quantum efficiencies (up to 0.07%) when 20% by weight of 2,5-di(biphenyl-4-ethynyl)-3,6-dimethylpyrazine 8 is added as a dopant: this is ascribed to the enhanced electron-transporting properties of the pyrazine system