Radiolabeling,Preparation, and Bioevaluation of 99mTc-Azathioprine as a Potential Targeting Agent for Solid Tumor Imaging

Radiochemistry - Azathioprine, an antitumor agent, was labeled with 99mTc using stannous chloride dihydrate as a reducing agent. Factors such as the amounts of the reducing agent and substrate, pH,...     

A new technique for multi-cell joint channel estimation in time division code division multiple access based on reduced rank singular value decomposition

A new technique for multi-cell joint channel estimation (MCJCE) in time division code division multiple access based on singular value decomposition (SVD) reduced rank technique is proposed in this paper. MCJCE is one of the effective solutions to improve the mobile system performance throughout mitigate the inter-cell interference form the neighboring cells. The increasing complexity of multi-cell system model due to the additional processing of the interferer users will be solved by using SVD reduced rank technique, where a limited number of parameter that really need it to describe the channel matrix will be estimated. Two models of multi-cell approaches are discussed, the first one depended on reconstruct the convolutional midamble matrix of inactive users in serving cell by the strongest interferer users from the neighboring cells. The second one will be more inclusive to user traffic scenarios in mobile systems and will be expanding to contain all detected users. The simulation results prove the validity of the proposed reduced rank technique for precision channel estimation (6.4 and 5 dB) and (9 and 7 dB) for case 1 and 2 respectively; BER performance improvements over the conventional estimators.     

Structural and Optical Characterization of Chemically Deposited PbS Thin Films

PbS thin films were deposited on glass substrates by a chemical bath deposition method. The effect of varying the film thickness on the structural and optical properties has been investigated. XRD analysis reveals the crystallinity of the deposited PbS films with (200) preferred crystal orientation. Increasing the film thickness enhances the crystallinity of the films as well as decreases the strain and dislocation density. The surface morphology features were dramatically changed from small spherical grains to bead-like shape. The absence of impurities in the deposited films was confirmed by energy dispersive x-ray spectrometry (EDX) measurements. The optical constants of the deposited films were calculated and a small decrease in the band gap energy was observed with increasing the film thickness.     

Radioiodinated Azilsartan as a New Highly Selective Radiotracer for Myocardial Perfusion Imaging

Radiochemistry - Azilsartan (AZ) was labeled with 131I using Chloramine-T as oxidizing agent. Factors affecting the labeling efficiency were systematically studied, and optimum conditions were...     

Labeling and biological evaluation of <Superscript>99<Emphasis Type="Italic">m</Emphasis></Superscript>Tc-tricarbonyl-chenodiol for hepatobiliary imaging

^99m Tc-tricarbonyl-labeled chenodiol (chenodeoxycholic acid, CDCA) intended for hepatobiliary imaging was prepared by 30-min heating at 100°C with a radiochemical yield of >98%. The radiolabeling yield and stability of the complex were evaluated using different chromatographic techniques. Biodistribution studies in Albino Swiss mice at different time intervals after administration of the complexes showed that the maximum uptake of the complexes in the liver was 35.5 ± 0.25% ID/g at 30 min post injection. ^99m Tc-tricarbonyl- CDCA shows promise for hepatobiliary imaging.     

Comparative Biological Evaluation of <Superscript>99<Emphasis Type="Italic">m</Emphasis></Superscript>Tc-Timonacic Acid Prepared Using Different Reducing Agents as a Complex for Hepatobiliary Imaging

Timonacic acid (TCA) was labeled with ^99mTc in the presence of three different reducing agents: NaBH₄, Na₂S₂O₄, and SnCl₂·2H₂O. The optimum conditions were as follows: with Na₂S₂O₄, pH 8, 7 mg of Na₂S₂O₄, room temperature, 2 mg of TCA, 30 min (radiochemical yield 98 ± 0.3%, complex was stable for 24 h); with NaBH₄, pH 8, 10 mg of NaBH₄, room temperature, 2 mg of TCA, 30 min (radiochemical yield 95 ± 0.3%, complex was stable for 6 h). The biodistribution of the complex in mice was studied. The liver uptake depends on the reducing agent used, reaching in 30 min 33.5 ± 0.3, 18.4 ± 0.18, and 22.3 ± 0.3% ID/g for the complexes prepared using Na₂S₂O₄, NaBH₄, and SnCl₂·2H₂O, respectively.     

Reduced Rank Technique for Joint Channel Estimation and Joint Data Detection in TD-SCDMA Systems

In time division-synchronous code division multiple access systems, the channel estimation for multiple subscribers requires the computation of very complicated algorithms through short training sequences. This situation causes mismodeling of the actual channels and introduces significant errors in the detected data of multiple users. This paper presents a novel channel estimation method with low complexity, which relies on reducing the rank order of the total channel matrix H. We exploit the rank deficient of H to reduce the number of parameters that characterizes this matrix. The adopted reduced rank technique is based on singular value decomposition algorithm. Equations for reduced rank-joint channel estimation (JCE) are derived and compared against traditional full rank-joint channel estimators: least square (LS) or Steiner, enhanced LS, and minimum mean square error algorithms. Simulation results of the normalized mean square error for the above mentioned estimators showed the superiority of reduced rank estimators. Multi-user joint data detectors based linear equalizers are used to suppress inter-symbol interference and mitigate intra-cell multiple access interference. The detectors: zero forcing block linear equalizer and minimum mean square error block linear equalizer algorithms are considered in this paper to recover the data. The results of bit error rate simulation have shown that reduced rank-JCE based detectors have an improvement by 5 dB lower than other traditional full rank-JCE based detectors.     

Preparation of 188Re-Labetalol as a β1-Adrenoceptor for Use in Nuclear Medicine

Radiochemistry - Labetalol was labeled with 188Re. The reaction conditions (amounts of stannous chloride and substrate, pH, time) were optimized, and the radiochemical yield as high as 95 ±...     

Reduced-rank technique for joint channel estimation in TD-SCDMA systems

In time division-synchronous code division multiple access systems, increasing the system capacity by exploiting the inserting of the largest number of users in one time slot (TS) requires adding more estimation processes to estimate the joint channel matrix for the whole system. The increase in the number of channel parameters due the increase in the number of users in one TS directly affects the precision of the estimator's performance. This article presents a novel channel estimation with low complexity, which relies on reducing the rank order of the total channel matrix H. The proposed method exploits the rank deficiency of H to reduce the number of parameters that characterise this matrix. The adopted reduced-rank technique is based on truncated singular value decomposition algorithm. The algorithms for reduced-rank joint channel estimation (JCE) are derived and compared against traditional full-rank JCEs: least squares (LS) or Steiner and enhanced (LS or MMSE) algorithms. Simulation results of the normalised mean square error showed the superiority of reduced-rank estimators. In addition, the channel impulse responses founded by reduced-rank estimator for all active users offers considerable performance improvement over the conventional estimator along the channel window length.     

Radiochemical and biological characterization of <Superscript>99<Emphasis Type="Italic">m</Emphasis></Superscript>Tc-oxiracetam as a model for brain imaging

^99mTc-oxiracetam was prepared. It can be used as a radiotracer for brain imaging. Under the optimum conditions (0.5 mg of oxiracetam, 50 μg of SnCl₂·2H₂O, pH 7, room temperature, 30 min), the radio-chemical yield determined by chromatographic methods reached 96%. Biodistribution studies with mice showed that the brain uptake of the complex was 5.1% injected dose per gram (% ID/g) at 5 min post injection. In this parameter, the complex surpasses the commercially available ^99mTc-ECD (4.7% ID/g) and ^99mTc-HMPAO (2.25% ID/g).