Study on emulsion copolymerization of styrene andn-butyl acrylate

Summary The emulsion copolymerization of styrene and n-butyl acrylate has been investigated. Copolymers were obtained at 70°C in the presence of sodium lauryl sulfate, an anionic micelle generator and ammonium persulfate as initiator. The ideal time of reaction, the effect of the amount of initiator, temperature and comonomer composition were also studied. The copolymers have been characterized through gel permeation chromatography (GPC) and Fourier transform infrared spectroscopy (FTIR).     

Myotonic dystrophy protein kinase gene expression in skeletal muscle from congenitally affected infants

Thiothrix spp., sulfide-oxidizing filamentous bacteria, were found to be a principal bacterial component of aquatic biofilms causing biofouling in selected municipal water storage tanks, private wells, and drip irrigation systems in Florida. Treatments of up to 200 ppm chlorine in the affected systems could not prevent return of the biofouling problem. The water originated from the upper Floridan aquifer and associated surficial aquifers in central and north Florida. Samples were examined where visible biofilms had a white, filamentous appearance, indicative of Thiothrix spp. The detection of Thiothrix spp. was confirmed by enzyme-liked immunosorbent assay (ELISA), indirect immunofluorescence (IIF), and microbiological procedures. It was estimated through immunocytochemical procedures that Thiothrix spp. comprised 18% of the biofilm in the municipal water storage tanks. These observations confirm that specific biological and chemical interactions may induce physical changes leading to significant biofouling.     

Hearing loss from combined exposures among petroleum refinery workers

Seventy-three consecutive cases of childhood acute lymphoblastic leukemia (ALL) diagnosed and managed in Queen Mary Hospital over a 10-year period from 1985 to 1994 were retrospectively analysed for their presenting features and treatment outcome. The 48 boys and 25 girls ranged in age from 0.4 to 14.2 years (median: 4.3 years). Bone and joint pain was a relatively common presenting feature besides fever, hepatosplenomegaly and lymphadenopathy. Immunophenotyping of blast cells showed: 51 B-cell precursor ALL, one B-ALL, 10 T-ALL and three myeloid-antigen positive ALL. Eight cases were unclassified since immunophenotyping had not been performed. Out of the 73 patients, treatment outcome was analysed in 20 cases treated with UKALL-VIII regimen and 28 cases treated with either the UKALL-XI regimen or the Hong Kong Children Cancer Study Group (HKCCSG) protocol which was modelled upon UKALL-XI. Although complete remission rates were similar between the two groups, patients treated with the former regimen that was less intensified suffered more relapses than the latter (56 per cent versus 21 per cent, P = 0.04). There were, however, no significant differences both in event-free survival (38.2 +/- 11.2 per cent versus 71.3 +/- 9.3 per cent, P = 0.12) and overall survival (70.0 +/- 10.2 per cent versus 79.6 +/- 8.3 per cent, P = 0.41) between the two groups at 3 years by long-rank test. With the use of risk-directed therapy and improved supportive care, two-thirds of our patients are able to enjoy long-term event-free survival.     

Mössbauer studies of phase separation in nanocrystalline Fe0.55−xCr0.45Snx alloys prepared by mechanical alloying

Mössbauer spectrometry (⁵⁷Fe and ¹¹⁹Sn) was used to investigate phase separation in coarse-grained Fe_0.55Cr_0.45 and in mechanically-alloyed nanocrystalline Fe_0.55Cr_0.45, Fe_0.52Cr_0.45Sn_0.03 and Fe_0.49Cr_0.45Sn_0.06 alloys during isothermal annealing at 748 K. Phase separation occurs faster in nanocrystalline Fe–Cr than in cold-rolled coarse-grained alloys. The effect of the interconnected microstructure on room-temperature hyperfine magnetic field distributions of alloys aged for hundreds of hours is qualitatively discussed. Tin hinders grain growth of nanocrystalline alloys.     

Improved burn scar assessment with use of a new scar-rating scale

The subjective assessment of scar appearance is a widely used method in the evaluation of burn outcomes and the efficacy of treatment methods. The purpose of this study is to design a numeric scar-rating scale with better interrater reliability than has previously been reported. The rating scale assesses scar surface, thickness, border height, and color differences between a scar and the adjacent normal skin. Eight raters were trained with use of a standardized set of photographs that provide examples of the scores to be assigned to each level of severity of each scar characteristic. The raters then rated 10 photographs of different scars, referring to the teaching set of pictures for comparison. The intraclass correlation (interrater reliability) was 0.94, 0.95, 0.90, and 0.85 for scar surface, border height, thickness, and color, respectively. This rating system has proved to be a useful tool for the evaluation of scar surface, thickness, border height, and color.     

ACTH-producing carcinoma of the pituitary with haematogenic metastases

Two laboratories equipped with CAS 200 (Becton Dickinson Image Cytometry Systems, San Jose, CA) instruments participated in this study of variability of DNA analysis of bladder tumor specimens. Formalin fixed paraffin embedded specimens were disaggregated and centrifuged onto microscope slides from ten bladder tumor specimens and two specimens of normal urothelium. Sources of variability considered were Specimen, Slide, Run, Laboratory, and Error. Slides were systematically scanned and 200 cells measured followed by the operator selecting 100 nuclei with abnormal morphology. DNA index (DI) and hyperdiploid fraction (HDF) were calculated from the DNA frequency distributions. For systematic sampling, 92% of the variability was due to Specimen indicating that differences in HDF values between specimens reflect biological differences. With selective sampling, only 67% of the variability in HDF is due to Specimen differences. Other factors, Laboratory, Error, and Laboratory x Specimen interaction each accounted for approximately 10% of the variability. Similarly variability of DI with selective sampling was also higher, and less specimen dependent than systematic sampling. It is important that sampling schemes and selection criteria be carefully documented in order to control variability. Enriched (or selective) sampling for abnormal cells has the potential to increase sensitivity but specimen classification based on these measurements must depend on determination of the frequency of such cells in the total population.     

Topical progesterone as support for the luteal phase in induced cycles

e efficacy and tolerability of 2.5% natural vaginal progesterone as luteal phase support in pharmacologically induced cycles has been evaluated. MATERIALS AND METHODS: On the basis of the administered therapy, the population studied was subdivided at random into four different groups. Sixty patients came to the Sterility Autonomous Department of the Niguarda Ca' Granda Hospital in Milan from November 1994 to January 1996. Both ultrasonographic and plasmatic hormonal parameters have been evaluated on a monthly basis. RESULTS: The plasma progesterone levels and ultrasonographic endometrial thickness average values resulted more important in groups treated with topical progesterone; in these same groups a greater percentage of pregnancies was observed. CONCLUSIONS: The results obtained demonstrated that the drug studied can be recommended as a valid luteal phase support in pharmacologically induced cycles.     

Polyethylenes produced with zirconocene immobilized on MAO-modified silicas

The effect of Al content on MAO-modified silicas was evaluated on catalyst activity, on polymer properties and on residual metal content in the resulting polyethylenes. MAO-modified silicas were prepared by impregnating MAO toluene solutions in concentration range between 0.5 and 20.0 wt% Al/SiO₂. Commercial MAO-modified silica (Witco) containing 24.4 wt% Al/SiO₂ was used for comparative reasons. The resulting modified-silicas were employed as supports for grafting (nBuCp)₂ZrCl₂. Using external MAO as cocatalyst (Al/Zr=2000) no difference in catalyst activity was observed. Nevertheless, for Al/Zr=500, catalyst activities were shown to be higher for supported zirconocene systems containing 0.0-2.0 wt% Al/SiO₂ range. According to DSC analysis, one T_m peak was detected for polymer obtained with catalyst prepared with 0.5 wt% Al/SiO₂ (135 °C), but two T_m peaks were observed for polymers obtained with catalysts prepared with 10.0 wt% Al/SiO₂ (136 and 141 °C) and 20.0 wt% Al/SiO₂ (133 and 141 °C).