Dual energy radiography using X-ray films and intensifying screens

The aim of this study was to investigate dual energy (DE) systems using X-ray films and intensifying screens as detecting media. This has been studied using both experimental methods and numerical modelling. Numerical methods were used to calculate energy losses due to K-fluourescent escape originating from the phosphors of the intensifying screens. This enabled the calculation of absorbed energy in screens. The method for screen selection and prediction of performance used the fact that detector response depends upon impinging X-ray energy. By equating the detector's absorbing characteristics to the resultant optical density (OD), an absorbed energy constant was calculated. These constants were used to predict OD for a given X-ray spectrum and hence simulation of detector characteristics. Experimental techniques were used to investigate sensitivity to chemical composition changes. These results compared favourably with computed values. It was demonstrated that although limitations exist, detector simulations are valid and X-ray film intensifying screen combinations make adequate DE detectors.     

X-ray intensifying screens greatly enhance the detection by autoradiography of the radioactive isotopes 32P and 125I

Detection of both γ-ray (¹²⁵I) and high energy β (³²P) particle-emitting radioisotopes by autoradiography is significantly enhanced by the use of X-ray intensifying screens. We have compared five commercially available intensifying screens (containing different inorganic phosphors) in combination with a number of films and exposure conditions. One calcium tungstate (Dupont, Cronex Lighting Plus intensifying screen produces an 8- to 10-fold enhancement in the detection of ³²P and a 30- to 40-fold enhancement in the detection of ¹²⁵I when an autoradiogram is made with Kodak RP ROYAL X-OMAT film at ?70°C. With one intensifying screen, 10 dpm of ³²P and 50 dpm of ¹²⁵I in an area of 10 mm² are readily detectable in a 20-hr exposure.     

Systems analysis of X-ray films of the vertebral column

The systems analysis of spinal X-ray films (SASXF) developed by the author solves the problem of an integral and, concurrently, detailed study of the spine of a patient on the basis of routine X-ray study. The examination of the patient gave rise to a patient's systems spinal model that considers the individual features of the vertebral column, which are most significant for a manual therapist's work. The standards of a X-ray study, a protocol form, and examination tools are described. An example of systems spinal model is given. The experience accumulated during studies of more than 2000 patients has shown that this procedure is highly effective in implementing medical manipulations by the methods of manual therapy.     

Systems analysis of X-ray films of the vertebral column

The systems analysis of spinal X-ray films (SASXF) developed by the author solves the problem of an integral and, concurrently, detailed study of the spine of a patient on the basis of routine X-ray study. The examination of the patient gave rise to a patient's systems spinal model that considers the individual features of the vertebral column, which are most significant for a manual therapist's work. The standards of a X-ray study, a protocol form, and examination tools are described. An example of systems spinal model is given. The experience accumulated during studies of more than 2000 patients has shown that this procedure is highly effective in implementing medical manipulations by the methods of manual therapy.     

The effect of sunlight and UV lamp exposure on EPR signals in X-ray irradiated touch screens of mobile phones

Radiation and Environmental Biophysics - Electron paramagnetic resonance (EPR) signals generated by ionizing radiation in touch-screen glasses have been reported as useful for personal dosimetry in...     

Characteristics of lactococci cultures produced in commercial media

Strains ofLactococcus lactis ssplactis andL. lactis sspcremoris were propagated on milk, three commercial highly buffered media (HB media), and four commercial media designed for external pH control (EC media). With milk and HB media, fermentation was allowed to proceed until a pH of 4.9 was reached. With EC media, pH was maintained at 6.0 with 5 N NH₄OH. The cultures were analyzed for chain length, viable population, specific acidifying activity (SAA) and specific proteolytic activity (SPA). The starters were stored at 4° C for 3 days, and analyses for chain length, viable population and SAA were repeated. It was more difficult to standardize medium composition with the rehydrated commercial blends, as their titratable acidities had greater proportional variations than milk. As a rule, chain length was longer in fresh cultures than in the stored starters, andL. lactis sppcremoris cultures had longer chains thanL. lactis ssplactis. All commercial media produced starters with total populations at least as high as that obtained in milk. With the EC media, populations could be five times greater than with milk; increases were less important in HB media. The increase in population in EC and HB media was more marked withL. lactis ssplactis than forL. lactis sspcremoris strains. Storage at 4° C for 3 days did not significantly reduceL. lactis populations, but mortality (up to 70%) was observed withL. lactis sspcremoris. The overall SAA ofL. lactis ssplactis cultures in EC media was 35% lower than milk- or HB media-grown starters, but the greater populations reached in EC media enabled a significant reduction in inoculation rate. Some statistically significant correlations were obtained between SAA and SPA (positive) as well as with chain length (negative), but the coefficients of determination were generally very low. The drop in pH during storage at 4° C was less with HB media than in milk, and was in relation to their buffering capacity.     

Systematic and large-scale two-hybrid screens

The increasing rate at which complete genome sequences become available necessitates rapid and robust methods for investigating the functions of their encoded proteins. Efforts have been made to study protein function by systematically screening large sets of proteins using the two-hybrid method. Analyses of the complete proteomes of baceriophage T7, the mammalian viruses hepatitis C and vaccinia, as well as of several protein complexes including RNA splicing proteins and RNA polymerase III from yeast, have been undertaken. Saccharomyces cerevisiae has been studied extensively by two-hybrid methods, with more than 2500 protein-protein interactions described. Systematic studies on metazoan proteomes are, however, still in their infancy.     

X-ray photoelectron spectroscopic and Raman analysis of silk fibroin-Cu(II) films

There is evidence to suggest that Cu(II) is involved in the natural spinning process of a silkworm helping to convert the concentrated silk fibroin (SF) solution (or dope) into tough insoluble threads. To investigate the interaction between SF and Cu(II), a series of regenerated SF (RSF) films with different mass ratios of Cu(II) to SF were prepared. X-ray photoelectron spectroscopy (XPS) was employed to study the chemical interaction between Cu(II) and SF in these Cu(II)-RSF films. A significant change in the binding energy of Cu 2p(3/2) demonstrated that the chemical state of Cu(II) in the Cu(II)-RSF films was affected by the interaction between Cu(II) and SF. Moreover, chemical shifts of N 1s and O 1s of SF were also detected, implying that Cu(II) may coordinate with both N and O atoms in the SF. In addition, Raman spectra of the same series of Cu(II)-RSF films recorded the conformation transition of SF that may occur by the coordination of Cu(II) and SF macromolecular chains.     

High-throughput screens and selections of enzyme-encoding genes

The availability of vast gene repertoires from both natural sources (genomic and cDNA libraries) and artificial sources (gene libraries) demands the development and application of novel technologies that enable the screening or selection of large libraries for a variety of enzymatic activities. We describe recent developments in the selection of enzyme-coding genes for directed evolution and functional genomics. We focus on HTS approaches that enable selection from large libraries (>10(6) gene variants) with relatively humble means (i.e. non-robotic systems), and on in vitro compartmentalization in particular.