Investigation of mean glandular dose versus compressed breast thickness relationship for mammography

The relationship between the mean glandular dose (MGD) and the compressed breast thickness (CBT) is commonly used for the presentation of mammographic dose survey results and could also be useful for the assessment of individual breast doses retrospectively in case of lack of necessary dosimetric instrumentation. The high data scattering from the best fit reduces the reliability of this technique. The aim of this study was to investigate the accuracy of this relationship using the data collected from a patient survey and phantom experiment. Patients were divided into three different groups according to their breast glandularities, which were predicted from the inspection of previous mammograms. X-ray beam qualities that will be used in patient examinations were determined according to breast thickness and predicted glandularities. The MGD versus CBT relationship for all the examined patients resulted in a poor correlation (R(2) = 0.28). This relationship was separately obtained for each glandularity group and also for sub-groups of specific beam qualities. The best correlation (R(2) = 0.73) was obtained for the fatty breast group and Mo/Mo combination. A low correlation (R(2) = 0.34) was observed in the mid-glandularity group due to inclusion of a wide range of glandularities in this group. In the case of the dense breast group, although the glandularity range was narrow, there were e still high data scattering (R(2) = 0.25). This was probably due to the use of Mo/Rh and Mo/Mo combinations. This is validated by obtaining the MGD-CBT relationship specific to Mo/Mo combination (R(2) = 0.61).     

Characterization of the effective atomic number for first row transition elements by the ratio of coherent to compton scattering intensities obtained by wavelength dispersive X-ray fluorescence

The effective atomic numbers of compounds of the first row transition elements were determined experimentally by a scattering method using wavelength dispersive X-ray fluorescence spectrometer. A calibration curve was created by using the intensity ratios of coherent to Compton scattered peaks of pure elements from atomic number 13–48. This relationship was employed to determine the effective atomic numbers of the compounds. The effective atomic numbers were also calculated by using empirical formulas from the literature. Mass attenuation coefficients were calculated using software. The experimentally measured values of the effective atomic numbers with the calculated values by empirical formulas were comparable.     

Effects of aging on latex film formation from polystrene particles: A photon transmission study

Aging due to the storage time on latex film formation was studied using the photon transmission method. The UV visible technique was used to monitor the evolution of transparency during film formation from two different polystyrene (PS) particles produced by using two different steric stabilizers, i.e., polyvinyl alcohol and polyvinyl pyrrolidone. The latex films were prepared from PS particles at room temperature before and after aging and annealed at elevated temperatures in various time intervals above glass transition (T_g). The increase in the transmitted photon intensity I_tr was attributed to the increase in the number of disappeared particle–particle interfaces. Relative decrease in transparency and delay in film formation were observed in the aged latex films compared to the nonaged ones. The Prager–Tirrell model was employed to interpret the increase in crossing density at the junction surface. The back and forth activation energies (ΔE) were measured and found to be dependent on aging for a diffusing polymer chain across the junction surface. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2014–2021, 2001     

Macro-azo-initiators having poly(ethylene glycol) units: Synthesis,characterization, and application to AB block copolymerization

Macro-azo-initiators (MAIs) having poly(ethylene glycol) (PEG) units were obtained by various multistep synthetic approaches. In the first stage, macro-azo-initiators of PEG type with azo groups inserted in the main chain were prepared. MAIs were then characterized by chemical analyses, spectral methods, ¹H-NMR, GPC, and DSC techniques. They were used in the free-radical bulk polymerization of dicyclohexylitaconate to synthesize AB block copolymers of poly(ethylene glycol-b-dicyclohexylitaconate) (PEG-b-PDCHI). © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2173–2181, 1997     

Comparison of one-dimensional and multi-dimensional models in stability analysis of turning operations

Chatter is one of the main problems in machining resulting in poor surface quality and low productivity. Chatter can be avoided by applying stability diagrams which are generated using stability models. The stability analysis of turning has mostly been performed using single dimensional, so-called oriented transfer function approach whereas the actual turning processes usually involve multi-dimensional dynamics. In this paper, a comparative analysis between one dimensional (1D) and multi-dimensional stability models is given for turning operations. The multi dimensional model includes the inclination and side edge cutting angles and insert nose radius in order to demonstrate their effect on absolute stable depth of cut predictions. Chatter experiments are conducted in order to compare with both model predictions. It is demonstrated that for higher inclination angles and insert nose radii 1D models result in significant errors, and multi-dimensional solutions are required.     

Use of ultrasonic energy in reactive dyeing of cellulosic fabrics

The use of ultrasonic energy in dyeing cotton fabrics with monochlorotriazine and vinylsulphone reactive dyes has been studied spectrophotometrically. The dyeings carried out conventionally and by the use of ultrasonic techniques were compared in terms of percentage exhaustion, total amount of dye transferred to the washing bath after dyeing, fastness properties and colour values of the dyed materials. Overall results have shown that the use of ultrasound in reactive dyeing of cellulosic fabrics can result in energy savings, less water consumption, increased depth of colour and better process conditions.     

Comparison of total‐etch,self‐etch,and selective etching techniques on class V composite restorations prepared by Er:YAG laser and bur: a scanning electron microscopy study

The purpose of this study was to compare total‐etch, self‐etch, and selective etching techniques on the marginal microleakage of Class V composite restorations prepared by Er:YAG laser and bur. Class V cavities prepared on both buccal and lingual surfaces of 30 premolars by Er:YAG laser or bur and divided into six groups. The occlusal margins were in enamel, and the cervical margins were in cementum. Group‐1: bur preparation(bp)+Adper Single Bond 2 (ASB)+Filtek Z550 (FZ); Group‐2: laser preparation(lp)+(ASB)+(FZ); Group‐3: bp + Clearfil S3 Bond Plus (CSBP)+(FZ); Group‐4: lp+(CSBP) (FZ); Group‐5: bp + acid etching+(CSBP)+(FZ); Group‐6: lp + acid etching+(CSBP)+(FZ). All teeth were stored in distilled water at 37°C for 24 hr, and then thermocycled 1000 times (5–55°C). Five teeth from each group were chosen for the microleakage investigation, and two teeth for the scanning electron microscope evaluation. Teeth which were prepared for the microleakage test were immersed in .5% methylene blue dye for 24 hr. After immersion, the teeth were sectioned and observed under a stereomicroscope for dye penetration. Data were analyzed using Kruskal–Wallis and Mann–Whitney U tests (p < .05). More microleakage was observed in the cervical regions compared to the occlusal regions in Groups 3, 5, and 6, respectively (p < .05). There is no statistically significant difference in Groups 1, 2, and 4, in terms of cervical regions versus occlusal regions (p > .05). No significant differences were observed among any groups in terms of occlusal and cervical surfaces, separately (p > .05). Different etching techniques did not influence microleakage of Class V restorations prepared by Er:YAG laser and bur.     

πSynthesis and evaluation of a series of α-hydroxy ethers derived from isopropyl oleate

Several fatty derivatives with bulky moieties were prepared by treatment of epoxidized isopropyl oleate with a number of alcohols in the presence of sulfuric acid catalyst to provide a series of α-hydroxy ethers in good yield. The materials were analyzed for cold flow performance through cloud point and pour point determinations. The most promising α-hydroxy ether produced in this study, with respect to both low temperature behavior and economic criteria, was isopropyl 9(10)-(2-ethylhexoxy) 10(9)-hydroxystearate, which has a cloud point of −23°C and pour point of −24°C.     

Metathesis of methyl soyate with ruthenium catalysts

Three ruthenium catalysts were investigated for the metathesis reaction of methyl soyate. Dichlorotris (triphenylphosphine) ruthenium II and bis (tricyclohexyl phosphine) benzylidine ruthenium (IV) dichloride displayed no reactivity at 40 °C and atmospheric pressure. However, ruthenium [1,3-bis-(2,4,6-trimethylphenyl)-2-imidazolidinylidene] dichloro (phenylmethylene) tricyclohexylphosphine, Grubbs second generation catalyst, exhibited high activity at these mild conditions. After 2 h, 46% of the unsaturated methyl esters in a commercial methyl soyate were metathesized. This suggests a method to modify the structure of methyl soyate to improve diesel fuel performance properties.