Scientific and Technological Research Council of Turkey

About: Scientific and Technological Research Council of Turkey is a government organization based out in Ankara, Turkey. It is known for research contribution in the topics: Laser & Antenna (radio). The organization has 2820 authors who have published 4507 publications receiving 70616 citations. The organization is also known as: TÜBITAK & Türkiye Bilimsel ve Teknolojik Araştırma Kurumu.

Characterization of the network structure of hydroxyl terminated poly(butadiene) elastomers prepared by different reactive systems

Abstract: Three types of hydroxyl terminated poly(butadiene) (HTPB) networks having different NCO/OH reactive group ratios were prepared using three different reactive systems (i.e., Desmodur N-100 pluriisocyanate, isophorone diisocyanate (IPDI)/trimethylol propane (TMP), and hexamethylene diisocyanate (HMDI)/TMP). Desmodur N-100 and TMP were used as polyfunctional reactants. The polymer–solvent interaction parameters (χ1) for HTPB–tetrahydrofuran (THF) and HTPB–chloroform systems at 45°C were determined, using a vapor pressure osmometer (VPO), as 0.31 and 0.24, respectively. Equilibrium swelling values of the networks in THF and chloroform and the data obtained by osmometry were further used for the calculation of the mean number-average molecular weight between junction points (Mc) of HTPB networks through the Flory-Rehner equation. The Mc values of each network, which were calculated from the swelling data obtained in THF and chloroform using the corresponding χ1 parameters for polymer–solvent systems, were found to be nearly the same. The changes in the mechanical, swelling, and the solubility properties of the networks prepared by three different reactive systems were followed. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 1129–1135, 1998

Gene expression and in vitro development of inter-species nuclear transfer embryos.

Abstract: This study examined the chromatin morphology, in vitro development, and expression of selected genes in cloned embryos produced by transfer of mouse embryonic fibroblasts (MEF) into the bovine ooplasm. After 6 hr of activation, inter-species nuclear transfer (NT) embryos (MEF-NT) had one (70%) or two pronuclei (20%), respectively. After 72 hr of culture in vitro, 62.6% of the MEF-NTs were arrested at the 8-cell stage, 31.2% reached the 2- to 4-cell stage, and only 6.2% had more than eight blastomeres, but none of these developed to the blastocyst stage. Whereas, 20% of NT embryos derived from bovine embryonic fibroblast fused with bovine ooplasm (BEF-NT) reached the blastocyst stage. Donor MEF nuclei expressing an Enhanced Green Fluorescent Protein (EGFP) transgene resulted in 1- to 8-cell stage MEF-NT that expressed EGFP. The expression of selected genes was examined in 8-cell MEF-NTs, 8-cell mouse embryos, enucleated bovine oocytes, and MEFs using RT-PCR. The mRNA for heat shock protein 70.1 (Hsp 70.1) gene was detected in MEF-NTs and MEF, but not in mouse embryos. The hydroxy-phosphoribosyl transferase (HPRT) mRNA was found in normal mouse embryos and MEF but not in MEF-NTs. Expression of Oct-4 and embryonic alkaline phospatase (eAP) genes was only detected in normal mouse embryos and not in the inter-species NT embryos. Abnormal gene expression profiles were associated with an arrest in the development at the 8-cell stage, but MEF-NT embryos appeared to have progressed through gross chromatin remodeling, typical of intra-species NT embryos. Therefore, molecular reprogramming rather than chromatin remodeling may be a better indicator of nuclear reprogramming in inter-species NT embryos. Mol. Reprod. Dev. 66: 334–342, 2003. © 2003 Wiley-Liss, Inc.

A high speed ASIC implementation of the Rijndael algorithm

Abstract: In this study, a non-pipelined implementation of the Rijndael Algorithm, which is selected to be the new Advanced Encryption Algorithm (AES) by the National Institute of Standards and Technology (NIST) in October 2000, is presented. Both the encryption and the decryption algorithms of Rijndael are implemented on a single ASIC. Using 149 K gates in a 0.35-/spl mu/m standard CMOS process, we have reached a 132 MHz worst-case clock speed yielding 2.41 Gbit/s non-pipelined throughput in both encryption and decryption.