Measurement of photon beam backscatter from collimators to the beam monitor chamber using target-current-pulse-counting and telescope techniques

Backscattered radiation (BSR) arising from field-defining collimators and entering the beam monitor chamber (BMC) may contribute to observed variations in medical linear accelerator photon beam output with collimator setting. Measuring the magnitude of such contributions for particular accelerators under specified operating conditions is therefore important when attempting to understand and model accelerator head scatter. The present work was conducted to confirm some backscatter measurements for collimating jaws reported previously and to extend these to include other accelerators and a multileaf collimator (MLC). BSR reaching the BMC from the jaws of Clinac 600C, 2100C and 2300CD accelerators and from an MLC on the 2300CD was investigated using both target-current-pulse-counting and telescope methods. Our measurements show that for the Clinac 600C BSR-dependent output variations are negligible. However, for the 2100C and 2300CD BSR-dependent relative output increased in an almost linear fashion, by up to 2.4% for 15 and 18 MV beams, and by up to 1.7% for 6 MV beams, as the field size varied from 5 x 5 cm2 to 40 x 40 cm2. The magnitude of BSR dependent upon collimator location in the head, as expected, thereby contributing to the collimator exchange effect. An earlier study at our centre using the telescope method had reported higher BSR levels. This discrepancy was resolved when corrections for telescope block and room scatter, previously assumed negligible, were made.     

Cost estimation of structural skeleton using an interactive automation algorithm: A conceptual approach

This paper addresses a new concept for generating bills of quantities (B.o.Qs) using AutoCAD drawings for a building project, which demonstrates the application of Industry Foundation Class (IFC), developed by International Alliance for Interoperability (IAI). The procedure considers types of materials and the structural shapes of the AutoCAD drawings to compute the cost of the structural skeleton elements using interactive automation. The main concept focuses on using layer computation of the AutoCAD drawing after converting it into a drawing inter-exchangeable file format (DXF). Once the coordinates are detected, it is easier to determine the area and volume for any structural shape, including circles and polygons. The extracting method is a new technique for structural engineers and quantity surveyors to estimate required material for beam, columns, slabs and foundations. The algorithm extracts and recognizes the layers and objects from a two dimensional DXF drawing along with the coordinates information. The results obtained using this technique are more accurate and reliable than manual procedures or any other traditional techniques. In this paper, an automated and interactive procedure for B.o.Q computation is demonstrated. The process involves a user-friendly interface, dynamic linking to the structural drawings and tracking of B.o.Q modifications at the same time.     

Expression and cellular distribution of baculovirus-expressed bovine herpesvirus 1 (BHV-1) glycoprotein D (gD) sequences

Glycoprotein D (gD) of bovine herpesvirus 1 (BHV-1), a homolog of herpes simplex virus gD, represents a major component of the viral envelope and is a dominant immunogen. To study the antigenic properties of the different regions of gD, we have expressed the full-length gD encoding gene and overlapping fragments spanning various regions of the gD open reading frame in a baculovirus (Autographa californica nuclear polyhedrosis virus)--insect cell (Spodoptera frugiperda, SF-9) system. Maximum levels of expression for all proteins were obtained 48 to 72 h post infection of SF-9 cells by recombinant viruses. Full-length and truncated recombinant gD proteins reacted specifically with anti-gD monospecific serum as determined by immunoprecipitation and immunoblotting, indicating that the proteins retained their antigenicity. However, based on the reactivity with a panel of gD-specific monoclonal antibodies (Mabs), the full-length recombinant gD lacked proper expression for two highly neutralizing linear epitopes identified by Mabs R54 and 9D6. The rest of the epitopes appeared to be preserved and antigenically unaltered. Immunofluorescence studies of recombinant baculovirus infected SF-9 cells using gD monospecific serum, revealed no direct correlation between cellular localization of the expressed proteins and their amino acid sequences.     

Fuzzy reliability analysis of nanocomposite ZnO beams using hybrid analytical-intelligent method

A hybrid analytical-intelligent approach is proposed for fuzzy reliability analysis of the composite beams reinforced by zinc oxide (ZnO) nanoparticle. The fuzzy reliability index corresponding to buckling failure mode of nanocomposite beam under thickness-direction external voltage is computed based on three-levels: (1) fuzzy analysis, (2) reliability analysis and (3) analytical buckling analysis. In fuzzy analysis level, an improved gravitational search algorithm has been applied to determine uncertainty interval for membership levels of reliability index. The adaptive formulation with a dynamical self-adjusting process is used for reliability analysis level based on conjugate first-order reliability method (FORM). The self-adjusting term in conjugate sensitivity vector is used to satisfy the sufficient descent condition for controlling instability of FORM formula while the proposed conjugate scalar factor is computed less than the original conjugate FORM, thus it may be provided with the efficient results for the convex problem. The new and previous sensitivity vectors obtained by conjugate and steepest descent vectors dynamically adjusted the proposed conjugate factor. In the buckling analysis level, an exponential theory in conjunction with the method of energy is utilized. Fuzzy random variables including applied voltage, the volume fraction of ZnO, thickness of beam, spring constant and shear constant of the foundation are considered in studied nanocomposite beam. Survey results indicated that the proposed method can provide stable and acceptable fuzzy membership functions for parametric study. Moreover, the ratio of length to thickness and spring constant of foundation are the more sensitive parameters which affect fuzzy reliability index significantly.

     

Modern Template Design and Biological Evaluation of Cephradine-loaded Magnesium Calcium Silicate Nanocomposites as an Inhibitor for Nosocomial Bacteria in Biomedical Applications

Silicon - Magnesium calcium silicate nanostructures (MCSNS) loaded with (0.0, 0.6, 0.9, and 1.2 wt%) of Cephradine-drug consisting of mesoporous particles were functionally prepared by sol-gel...     

X-ray Fluorescence Uptake Measurement of Functionalized Gold Nanoparticles in Tumor Cell Microsamples

Quantitative cellular in vitro nanoparticle uptake measurements are possible with a large number of different techniques, however, all have their respective restrictions. Here, we demonstrate the application of synchrotron-based X-ray fluorescence imaging (XFI) on prostate tumor cells, which have internalized differently functionalized gold nanoparticles. Total nanoparticle uptake on the order of a few hundred picograms could be conveniently observed with microsamples consisting of only a few hundreds of cells. A comparison with mass spectroscopy quantification is provided, experimental results are both supported and sensitivity limits of this XFI approach extrapolated by Monte-Carlo simulations, yielding a minimum detectable nanoparticle mass of just 5 pg. This study demonstrates the high sensitivity level of XFI, allowing non-destructive uptake measurements with very small microsamples within just seconds of irradiation time.     

Preparation,Properties and Applications of the Hybrid Organic/Inorganic Nanocomposite Based on Nanoporous Carbon Matrix

Journal of Inorganic and Organometallic Polymers and Materials - Nanoporous carbon matrix was prepared by the sol–gel process from pyrogallol-formaldehyde (PF) mixtures in water using picric...     

Influence of current density on oxygen transfer in an electroflotation cell

The objective of this work is to study the transfer of oxygen from gas to liquid phase in an electroflotation cell. The measurements were performed in a laboratory scale cell using insoluble electrodes, titanium coated with ruthenium oxide as anode and stainless steel as cathode. The volumetric mass transfer coefficient K _L a, was characterized for clean tap water as liquid phase for different values of current density (J). The global coefficient of mass transfer based on the liquid film, K _L , and the specific interfacial area, a, were characterized. A model which relates K _L a to current density was established. Different evaluation criteria of oxygen transfer in electroflotation process were determined and compared with other aeration process.     

Glass transition and the rigid amorphous phase in semicrystalline blends of bacterial polyhydroxybutyrate PHB with low molecular mass atactic R, S-PHB-diol

The glass transition and the crystallinity of blends of isotactic bacterial PHB and low molecular mass atactic R, S-PHB-diols was investigated by means of differential scanning calorimetry (DSC), temperature-modulated DSC and dielectric spectroscopy. It was found that (i) T_g of crystallized blends is much lower than T_g of quenched blends, (ii) the semi-crystalline blends can only be described with a three-phase model. From the experimental results the amount of the oligomer component in the mobile amorphous as well as in the rigid amorphous phase was determined. It could be shown that the low molecular mass atactic R, S-PHB-diol is enriched in the mobile amorphous phase of the semi-crystalline blends, but 5-15% oligomer remains, however, in the rigid amorphous phase.     

Repeated Budgeted Second Price Ad Auction

Our main goal is to abstract existing repeated sponsored search ad auction mechanisms which incorporate budgets, and study their equilibrium and dynamics. Our abstraction has multiple agents bidding repeatedly for multiple identical items (such as impressions in an ad auction). The agents are budget limited and have a value per item. We abstract this repeated interaction as a one-shot game, which we call budget auction, where agents submit a bid and a budget, and then items are sold by a sequential second price auction. Once an agent exhausts its budget it does not participate in the proceeding auctions. Our main result shows that if agents bid conservatively (never bid above their value) then there always exists a pure Nash equilibrium. We also study simple dynamics of repeated budget auctions, showing their convergence to a Nash equilibrium for two agents and for multiple agents with identical budgets.