Radiostrontium separation from sodium molybdate solution and its measurement using LSA: an application to radiopharmaceutical analysis

Technetium (^99mTc), a decay product of molybdenum (⁹⁹Mo), is employed as radioisotope in nuclear medicine. Several practical devices known as generators are commercially available which enable the user to separate the daughter from the parent radionuclide. The present study is focused on quality control of chromatographic technetium generator. A properly constructed generator should comply with international requirements of radionuclide purity of ⁹⁰Sr/⁹⁹Mo ≤ 6 × 10^?8 and ⁸⁹Sr/⁹⁹Mo ≤ 6 × 10^?7. For this purpose an analytical method was optimized to quantify radiostrontium (⁸⁹Sr and ⁹⁰Sr) in sodium molybdate [Na ₂ ⁹⁹ MoO₄] solution, a fission product used for ⁹⁹Mo/^99mTc generators. Dowex 1 × 8 and alumina were used in sequence followed by tributyl phosphate extraction for radiostrontium separation. Cerenkov measurement of ⁸⁹Sr and ⁹⁰Sr (through its descendent ⁹⁰Y) was performed using Perkin Elmer Tricarb LSA 3170 with detection efficiency of 42 and 14 %, respectively. Since efficiency of Cerenkov counting is sensitive to presence of color, spectral index of sample was used to correct the counting efficiency. The chemical recovery for strontium was 22 % and for yttrium was 80 % as determined by inductively coupled plasma optical emission spectrometry. Lower limit of detection was found to be 6.3 and 14.4 Bq L^?1 for ⁹⁰Sr and ⁸⁹Sr, respectively with 60 min counting time. Hence method can be applied successfully to analyze ^89,90Sr in fission molybdenum used as radiopharmaceutical with a relative error of <10 %.     

Synthesis and biological evaluation of benzimidazole pendant cyanopyrimidine derivatives as anticancer agents

Thirteen new benzimidazole pendant cyanopyrimidine derivatives were synthesized. The compounds were synthesized through multistep reaction protocol. The structures of synthesized derivatives were studied by EI-MS, ¹H NMR, FT-IR and elemental analysis. All the compounds were studied for their anticancer activity at National Cancer Institute. Except compound 7j , all the compounds unveiled cytotoxicity against cancer cells. The most active compound 7a had shown highest value of growth inhibition of 88.44% and 84.19% against HOP-92 and T-47D cancer cell lines.     

Near-infrared Raman spectroscopy of single optically trapped biological cells

We report on the development and testing of a compact laser tweezers Raman spectroscopy (LTRS) system. The system combines optical trapping and near-infrared Raman spectroscopy for manipulation and identification of single biological cells in solution. A low-power diode laser at 785 nm was used for both trapping and excitation for Raman spectroscopy of the suspended microscopic particles. The design of the LTRS system provides high sensitivity and permits real-time spectroscopic measurements of the biological sample. The system was calibrated by use of polystyrene microbeads and tested on living blood cells and on both living and dead yeast cells. As expected, different images and Raman spectra were observed for the different cells. The LTRS system may provide a valuable tool for the study of fundamental cellular processes and the diagnosis of cellular disorders.     

Synthesis of Poly(3,4‐ethylenedioxythiophene) latexes using poly(N‐vinylpyrrolidone)‐based copolymers as reactive stabilizers

The synthesis by oxidative polymerization of well‐defined poly(3,4‐ethylenedioxythiophene) (PEDOT) nano‐objects in the presence of modified and unmodified poly(N‐vinylpyrrolidone)‐based copolymers used as stabilizers in aqueous media is reported. Ammonium persulfate or a mixture of ammonium persulfate with CuCl₂ or CuBr₂ was used as oxidants. The effects of several parameters such as the molar mass and the concentration of the stabilizer as well as the nature of the oxidants on the size, morphology, and the conductivity of the PEDOT particles have been investigated. The distribution of the reactive moieties along the copolymer stabilizer backbone was shown to be crucial to get well‐defined PEDOT nano‐objects. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3841–3855, 2010     

Anisotropic Lithium Ion Conductivity in Single‐Ion Diblock Copolymer Electrolyte Thin Films

Well‐defined single‐ion diblock copolymers consisting of a Li‐ion conductive poly(styrenesulfonyllithium(trifluoromethylsulfonyl)imide) (PSLiTFSI) block associated with a glassy polystyrene (PS) block have been synthesized via reversible addition fragmentation chain transfer polymerization. Conductivity anisotropy ratio up to 1000 has been achieved from PS‐b‐PSLiTFSI thin films by comparing Li‐ion conductivities of out‐of‐plane (aligned) and in‐plane (antialigned) cylinder morphologies at 40 °C. Blending of PS‐b‐PSLiTFSI thin films with poly(ethylene oxide) homopolymer (hPEO) enables a substantial improvement of Li‐ion transport within aligned cylindrical domains, since hPEO, preferentially located in PSLiTFSI domains, is an excellent lithium‐solvating material. Results are also compared with unblended and blended PSLiTFSI homopolymer (hPSLiTFSI) homologues, which reveals that ionic conductivity is improved when thin films are nanostructured.

     

An ILP and simulation model to optimize search and rescue helicopter operations

Maritime search and rescue (SAR) operations, conducted for rendering aid to the victims in need of help at sea, play a crucial role in dropping the number of causalities. Therefore, it is of high importance to organize SAR operations properly. In this paper, we compose a hybrid methodology which combines optimization and simulation to allocate SAR helicopters. First, we build an integer linear programming (ILP) model to provide an effective deployment plan and use it as an input to a simulation model which includes constraints that the ILP model cannot tackle. Next, using a rule-based algorithm, we generate alternative solutions and seek better plans that exist in the vicinity of the ILP model solution. We perform our methodology on the historical incident data in the Aegean Sea region. Results show that the hybrid methodology we adopted leads to a more effective utilization of resources than the optimization model alone.     

An analysis of p-median location problem: Effects of backup service level and demand assignment policy

Any solution to facility location problems will consider determining the best suitable locations with respect to certain criteria. Among different types of location problems, involving emergency service system (ESSs) are one of the most widely studied in the literature, and solutions to these problems will mostly aim to minimize the mean response time to demands. In practice, however, a demand may not be served from its nearest facility if that facility is engaged in serving other demands. This makes it a requirement to assign backup services so as to improve response time and service quality. The level of backup service is a key, strategic-level planning factor, and must be taken into consideration carefully. Moreover, in emergency service operations conducted in congested demand regions, demand assignment policy is another important factor that affects the system performance. Models failing to adopt sufficient levels of backup service and realistic demand assignment policies may significantly deteriorate the system performance.Considering the classic p-median problem (pMP) location model, this paper investigates the effects of backup service level, demand assignment policy, demand density, and number of facilities and their locations on the solution performance in terms of multiple metrics. For this purpose, we adopt a combined optimization and simulation approach. We will first modify the classic pMP to account for distances to backup services. Next, we employ a discrete event simulation to evaluate the performance of location schemes obtained from the deterministic mathematical model. Our results provide insights for decision-makers while planning ESS operations.     

Growth of Cu0.5Tl0.5Ba2Ca3Cu4−yZnyO12−δ superconductor with optimum carriers

We have tried to vary the carriers concentration in Cu_0.5Tl_0.5Ba₂Ca₃Cu_4?yZn_yO_12?δ (y = 0, 1, 1.5, 2, 2.5) superconductor with the help of post-annealing experiments carried out in nitrogen, oxygen and air and to investigate its effects on the superconductivity parameters. The zero resistivity critical temperature [T_c(R = 0)], the magnitude of diamagnetism and critical current [I_c(H = 0)] are found to increase in Zn free samples after post-annealing in oxygen and air, while these superconducting properties have been suppressed after post-annealing in nitrogen at 550 °C for 6 h. The post-annealing of Zn-doped samples in air has marginally increased the superconducting properties, while these properties have been suppressed after post-annealing in nitrogen and oxygen. These studies have led us to the definite conclusion that the Zn-doped material has grown with optimum carriers concentration.     

Estimation of background radiation levels and associated health risks in mineral rich district Chiniot,Pakistan

The mineral extraction activities may disturb the natural radioactivity, therefore current study aims to generate baseline data of natural radionuclides and anthropogenic ¹³⁷Cs before the start of industrial activities. Gamma spectrometry and gross alpha and beta counting systems were used for activity measurement in environmental samples. In soil, the mean activity of ²³²Th, ²²⁶Ra, ⁴⁰K and ¹³⁷Cs were determined as 79 (66–117), 47 (34–80), 823 (602–1159) and 1.3 (1.1–4.5) Bq kg^?1, respectively. The average annual effective dose rate (128.7 µSv h^?1) in the study area was twice higher than world’s average value. Indoor hazard index was greater than unity at two places; therefore, proper ventilation is proposed during construction.