Novel slag/natural rubber composite as flexible material for protecting workers against radiation hazards.

This work is an attempt to employ the electric arc furnace (EAF) slag as a by-product material to develop an alternative and environmentally friendly material for gamma-radiation protection applications such as in medical and industrial areas. For this purpose, different concentrations of micro-sized EAF slag (0, 20, 40, 60, 80, 100, 500, and 800 phr) were incorporated as fillers in the natural rubber (NR) matrix to produce the shielding composites. In addition, nano-sized EAF slag particles were prepared by using a high-energy ball milling technique to investigate the effect of particle size on the gamma-radiation shielding properties. The synthesized micro and nano EAF/NR composites were tested as protective materials against gamma-radiation by employing NaI(Tl) scintillation detector and standard radioactive point sources (152Eu, 137Cs, 133Ba, and 60Co). Different shielding parameters such as linear and mass attenuation coefficient, half value layer (HVL), tenth value layer, mean free path, effective atomic number (Zeff), and effective electron density (Neff) were determined to assess the radiation shielding capability of the EAF/NR composites. Furthermore, equivalent atomic number (Zeq) and the exposure buildup factor values for photon energy in the range from 0.015 to 15 MeV were also computed by Geometric Progression method. The experimental results of micro EAF/NR composites showed that at 121.78 keV, EAF0 composite (without EAF slag content) had the lowest µ value of 0.1695 cm-1, while the EAF800 composite (which was loaded with 800 phr of micro EAF slag) had the highest µ value of 0.2939 cm-1 at the same energy, which in turn decreases the HVL from 4.09 to 2.36 cm, respectively. Therefore, increasing the filler weight fractions of EAF slag in the NR matrix, increases the shielding properties of the composites. Moreover, the NR composite reinforced with 800 phr of nano EAF slag has better gamma-radiation shielding efficiency compared to that filled with 800 phr of micro EAF slag. The success of this work was to prepare a flexible, lightweight, low-cost, and lead-free material with better shielding capability.

Influence of degree of substitution and folic acid coinitiator on pullulan-HEMA hydrogel properties crosslinked under visible-light initiating system.

Hydroxyethyl methacrylate-derivative pullulan (pullulan-HEMA) was synthesized by activation of HEMA followed by catalyzed reaction for adjusting the degree of substitution (DS) of copolymer. Pullulan-HEMA was photocrosslinked using new three-components photoinitiating system composed of carboxylated camphorquinone-folic acid-iodonium salt under visible light. Folic acid was employed as new coinitiator for improving the entire hydrogel properties and avoiding harms of traditional used tertiary amine coinitiators. Pullulan-HEMA hydrogels were characterized by swelling, crosslinking density, and degree of conversion. It was observed that the increase of crosslinking density, Tg, degree of conversion are owing to increasing the DS of copolymer. However, water uptake of hydrogel decreased with increasing the DS value and folic acid concentrations, owing to increasing the crosslinking densities of hydrogels. Also, increasing DS of copolymer and folic acid improved sharply hydrogel surface morphology and prolonged the required time for enzymatic degradation. Notably, the alteration in DS of copolymer converted the in vitro release profile of dexamethasone from rapid and big burst release into sustained and low release behavior. Meanwhile, we could obtain progressive and tunable storage modulus ranged ca. 2.0-10 KPa when DS of copolymer was altered from 0.025 to 0.086, showing that pullulan-HEMA hydrogels are promising biomaterial candidate for biomedical applications.

Psychotropic drugs in Bulgaria-frequency and risk of adverse drug reactions.

The aim of the study is to determine the frequency and risk of appearance of adverse drug reactions/ADRs/during the treatment with psychotropic drugs. The first part of the study is an analysis of the use of the psychotropic drugs for one-year period of time in our country, performed by DDD methodology. An attempt is made to equalize the Bulgarian list of the psychotropic drugs with the ATC classification and to estimate the DDD/1000/day. The data for Bulgaria is compared with that of the other countries. The collected data for the psychotropic drug use is divided into 2 groups: Psycholeptics and Psychoanaleptics. It is made an attempt to explain the main differences between them. The number of the standard therapeutic courses/NT/is used for assessment of the frequency and risk of ADRs. The results from the study show that the determined frequency of appearance of ADR for the different drugs is within "rare" and "very rare' for 100,000 inhabitants, according to the WHO terminology. Only for the drug Tardyl (EGIS Pharmaceuticals, Hungary) with INN Aminobarbitalum + Glutethimidum + Promethazini hydrochloridum the frequency is above 1%. That fact makes us to recommend a limitation of the prescription and usage of this drug to the Bulgarian Ministry of Health and to the National Drug Agency.

Reactive bone marrow changes in infectious spondylitis: quantitative assessment with MR imaging.

PURPOSE: To evaluate diffuse, reactive bone marrow changes in unaffected vertebrae on magnetic resonance (MR) images in patients with proved infectious spondylitis. MATERIALS AND METHODS: Percentage signal intensity increase of the unaffected bone marrow on contrast material-enhanced MR images (percentage enhancement) was calculated retrospectively in 22 cases of infectious spondylitis and 86 cases without bone marrow disease. Multiple regression analysis and Student t test statistics were performed. RESULTS: Multiple regression analysis showed a significant influence of age and the presence of spondylitis on the values of percentage enhancement (P: <.001). For those aged 35 years or younger, the mean percentage enhancement was 43.2% +/- 4.0 for patients with infectious spondylitis (n = 3) and was 26.4% +/- 8.6 for the control group (n = 23). For those older than 35 years, the mean percentage enhancement was 28.2% +/- 12.2 for patients with infectious spondylitis (n = 19) and 17.5% +/- 7.9 (P: <.001) for the control group (n = 63). Six (27%) of 22 patients with infectious spondylitis showed abnormal percentage enhancement values in unaffected bone marrow when the upper limit of the normal value was 2 SDs above the mean of the control group. CONCLUSION: On MR images, reactive bone marrow changes can be found in unaffected vertebrae in patients with infectious spondylitis. The signal intensity changes and increased percentage enhancement associated with this disease are similar to those of myeloproliferative and diffuse neoplastic disorders and bone marrow stimulation in hemolytic anemia.

Previously treated, locally recurrent breast cancer: treatment with superselective intraarterial chemotherapy.

PURPOSE: To evaluate the effectiveness of intraarterial infusion chemotherapy (IAC) with mitoxantrone hydrochloride in patients with previously treated, locally recurrent breast cancer. MATERIALS AND METHODS: Thirty-nine women (aged 31-82 years) with recurrent breast cancer underwent superselective IAC (25 mg/m2 mitoxantrone hydrochloride every 24 hours) through the subclavian artery branches after heparin administration. The extent of tumor perfusion was monitored with computed tomography during the intraarterial administration of contrast medium. IAC was repeated one to nine times. Patients had previously undergone radiation therapy (n = 39), surgery (n = 20), or systemic chemotherapy (n = 23). RESULTS: The overall response rate was 77% (n = 30). Eight patients had complete remission. Progression occurred in three patients. Remission was observed in cases of lymph node involvement (n = 9). Seven patients are still undergoing treatment. Side effects were usually moderate. Nine patients died of systemic tumor spread. In 14 patients, distant metastases developed during the first 18 months of treatment. CONCLUSION: IAC is an effective, well-tolerated therapy in patients with locally recurrent breast cancer.