Investigating the robustness of a learning-based method for quantitative phase retrieval from propagation-based x-ray phase contrast measurements under laboratory conditions

Quantitative phase retrieval (QPR) in propagation-based x-ray phase contrast imaging of heterogeneous and structurally complicated objects is challenging under laboratory conditions due to partial spatial coherence and polychromaticity. A learning-based method (LBM) provides a non-linear approach to this problem while not being constrained by restrictive assumptions about object properties and beam coherence. In this work, a LBM was assessed for its applicability under practical scenarios by evaluating its robustness and generalizability under typical experimental variations. Towards this end, an end-to-end LBM was employed for QPR under laboratory conditions and its robustness was investigated across various system and object conditions. The robustness of the method was tested via varying propagation distances and its generalizability with respect to object structure and experimental data was also tested. Although the LBM was stable under the studied variations, its successful deployment was found to be affected by choices pertaining to data pre-processing, network training considerations and system modeling. To our knowledge, we demonstrated for the first time, the potential applicability of an end-to-end learning-based quantitative phase retrieval method, trained on simulated data, to experimental propagation-based x-ray phase contrast measurements acquired under laboratory conditions. We considered conditions of polychromaticity, partial spatial coherence, and high noise levels, typical to laboratory conditions. This work further explored the robustness of this method to practical variations in propagation distances and object structure with the goal of assessing its potential for experimental use. Such an exploration of any LBM (irrespective of its network architecture) before practical deployment provides an understanding of its potential behavior under experimental settings.Comment: Under review as a journal submission. Early version with partial results has been accepted for poster presentation at SPIE-MI 202

Mikrosfere ropinirol hidroklorida za polagano oslobađanje: Utjecaj procesnih parametara

An emulsion solvent evaporation method was employed to prepare microspheres of ropinirole hydrochloride, a highly water soluble drug, by using ethylcellulose and PEG with the help of 32 full factorial design. The microspheres were made by incorporating the drug in a polar organic solvent, which was emulsified using liquid paraffin as an external oil phase. Effects of various process parameters such as viscosity of the external phase, selection of the internal phase, surfactant selection and selection of stirring speed were studied. Microspheres were evaluated for product yield, encapsulation efficiency and particle size. Various drug/ethylcellulose ratios and PEG concentrations were assayed. In vitro dissolution profiles showed that ethylcellulose microspheres were able to control release of the drug for a period of 12 h.Mikrosfere ropinirol hidroklorida, ljekovite tvari vrlo dobro topljive u vodi, pripravljene su metodom isparavanja otapala, koristeći etilcelulozu i PEG te 32 potpuno faktorijalno dizajniranje. Mikrosfere su pripravljene na sljedeći način: otopina ljekovite tvari u polarnom organskom otapalu emulgirana je s tekućim parafinom kao vanjskom uljnom fazom. Ispitivan je utjecaj različitih procesnih parametara poput viskoznosti vanjske faze, vrste interne faze i površinski aktivne tvari te brzine miješanja. Za pripravljene mikrosfere određeno je iskorištenje, učinkovitost inkapsuliranja i veličina čestica. Isprobavani su različiti odnosi ljekovite tvari i etilceluloze te koncentracija PEG-a. In vitro pokusi su pokazali da je oslobađanje ljekovite tvari kontrolirano tijekom 12 h

Učinak topljivosti na kinetiku oslobađanja vodotopljivih i vodonetopljivih lijekova iz matriksnog sustava na bazi HPMC

The purpose of the present research work was to observe the effects of drug solubility on the release kinetics of water soluble verapamil hydrochloride and insoluble aceclofenac from polymer based matrix formulations. Matrix formulations were prepared by the direct compression method. The formulations were evaluated for various physical parameters. Along with the dynamics of water uptake and erosion, SEM and in vitro drug release of tablets were studied. Applying an exponential equation, it was found that the kinetics of soluble drug release followed anomalous non-Fickian diffusion transport whereas insoluble drug showed zero-order release. SEM study showed pore formation on the tablet surface that differed depending on drug solubility. t-Test pointed to a significant difference in the amount of both drugs released due to their difference in solubility. Solubility of the drug affects the kinetics and the mechanism of drug release.Cilj rada bio je praćenje učinka topljivosti na kinetiku oslobađanja vodotopljivog verapamil hidroklorida i netopljivog lijeka aceklofenaka iz matriksnih sustava na bazi hidrofilnog polimera. Matriksni sustavi pripravljeni su izravnom metodom kompresije. Uz ispitivanje uobičajenih fizikalnih svojstava, ispitivana je i dinamika primanja vode, te erozija, SEM i in vitro oslobađanje ljekovite tvari iz tableta. Primjenom eksponencijalne jednadžbe utvrđeno je da mehanizam oslobađanja topljivih lijekova slijedi anomalni ne-Fickov difuzijski transport, dok netopljivi lijekovi slijede kinetiku nultog reda. SEM ispitivanja pokazala su pore na površini matriksa ovisne o topljivosti ljekovite tvari. T-test ukazuje da količina oslobođenog lijeka značajno ovisi o njegovoj topljivosti. Topljivost lijeka ima značajan učinak na kinetiku i mehanizam oslobađanja

Improving the biopharmaceutical attributes of mangiferin using vitamin E-TPGS co-loaded self-assembled phosholipidic nano-mixed micellar systems

The current research work encompasses the development, characterization, and evaluation of self-assembled phospholipidic nano-mixed miceller system (SPNMS) of a poorly soluble BCS Class IV xanthone bioactive, mangiferin (Mgf) functionalized with co-delivery of vitamin E TPGS. Systematic optimization using I-optimal design yielded self-assembled phospholipidic nano-micelles with a particle size of  80% of drug release in 15 min. The cytotoxicity and cellular uptake studies performed using MCF-7 and MDA-MB-231 cell lines demonstrated greater kill and faster cellular uptake. The ex vivo intestinal permeability revealed higher lymphatic uptake, while in situ perfusion and in vivo pharmacokinetic studies indicated nearly 6.6- and 3.0-folds augmentation in permeability and bioavailability of Mgf. In a nutshell, vitamin E functionalized SPNMS of Mgf improved the biopharmaceutical performance of Mgf in rats for enhanced anticancer potency

Photocatalytic splitting of water.

The use of photocatalysis for the photosplitting of water to generate hydrogen and oxygen has gained interest as a method for the conversion and storage of solar energy. The application of photocatalysis through catalyst engineering, mechanistic studies and photoreactor development has highlighted the potential of this technology, with the number of publications significantly increasing in the past few decades. In 1972 Fujishima and Honda described a photoelectrochemical system capable of generating H2 and O2 using thin-film TiO2. Since this publication, a diverse range of catalysts and platforms have been deployed, along with a varying range of photoreactors coupled with photoelectrochemical and photovoltaic technology. This chapter aims to provide a comprehensive overview of photocatalytic technology applied to overall H2O splitting. An insight into the electronic and geometric structure of catalysts is given based upon the one- and two-step photocatalyst systems. One-step photocatalysts are discussed based upon their d0 and d10 electron configuration and core metal ion including transition metal oxides, typical metal oxides and metal nitrides. The two-step approach, referred to as the Z-scheme, is discussed as an alternative approach to the traditional one-step mechanism, and the potential of the system to utilise visible and solar irradiation. In addition to this the mechanistic procedure of H2O splitting is reviewed to provide the reader with a detailed understanding of the process. Finally, the development of photoreactors and reactor properties are discussed with a view towards the photoelectrochemical splitting of H2O

Design and Development of a Neutron/X-Ray Combined Computed Tomography System At Missouri S&T

A new method for non-destructive analysis has been developed using a combined neutron/X-ray imaging system at the Missouri Science and Technology Reactor (MSTR). The interactions of neutrons and X-ray photons with matter produce differing characteristic information, resulting in distinctly different visual images. In order to obtain a more comprehensive picture of the structural and compositional data for a desired object, a prototype imaging system has been designed which utilizes neutron and X-ray imaging simultaneously without obstructing the beam geometry for each imaging mechanism. The current system is optimized for the imaging of small to medium sized objects of 0.5-50 mm. This new imaging capability in place at the MSTR promises great advances in the field of non-destructive testing, especially for nuclear engineering, nuclear medical science, and material science research. In an imaging object, a range of atomic number values and thermal cross-sections may be present. Where multiple materials having similar atomic number and differing thermal cross-section or vice versa may be present, exclusive neutron or X-ray analysis may exhibit shortcomings in distinguishing interfaces. However, fusing the neutron image and X-ray image into a combined image offers the strengths of both and may provide a superior method of analysis. In this paper, a novel combined X-ray and neutron imaging system will be introduced for superior analysis of certain imaging objects. Design details of experimental set-up and examples of preliminary imaging tests from individual modality will be detailed. © Akadémiai Kiadó, Budapest, Hungary 2012

High efficiency Copper Indium Gallium Diselenide (CIGS) by high Power Impulse Magnetron Sputtering (HIPIMS): a promising and scalable application in thin-film photovoltaics

A novel method to deposit Copper Indium Gallium Diselenide (CIGS) using High Power Impulse Magnetron Sputtering (HIPIMS) was demonstrated and compared to the existing DC magnetron sputtering process. The metal-ion assisted thin-film growth inherent to a HIPIMS deposition process was used to advantage in depositing CIGS films. The HIPIMS plasma was characterized by measuring ion currents on a Langmuir probe placed into the plasma sufficiently close to the substrate. The high density plasma consisting of both metal and metal ions resulted in CIGS thin-film solar cells of superior conversion efficiencies (∼13%) as compared to conventional DC magnetron sputtering (∼10%). The efficiency enhancement was attributed to the improvement in the shunt resistance of the solar cell which corresponds to the increase in the density of the CIGS layer. Furthermore, it was also possible to grow large grained CIGS (∼1 micron) with high mobility metal-ions from the HIPIMS process. The scalability potential of the HIPIMS CIGS process was also demonstrated by running a 1.5 m long Copper-Indium-Gallium rotatable in a selenium environment using a HIPIMS power supply. The cylindrical magnetron was run at an average power of 7.8 KW and peak powers of as much as 300 KW with controlled arcing. The existence of a HIPIMS plasma was confirmed by the ion currents on the Langmuir probe and the metal signals from a Plasma Emission Monitor (PEM). © 2010 Materials Research Society

Development of Analytical Formulae to determine the Response of Submerged Composite Plates subjected to Underwater Explosion

International audienceClosed-form analytical formulae are developed to analyze the bending response of submerged composite rectangular plates subjected to underwater explosions (UNDEX). These explosions are supposed to occur at a sufficiently large stand-off distance so that a uniformly distributed pressure pulse can be applied and the corresponding bubble effects can be ignored. The plate is considered in an air-backed condition. The derivation steps are divided into two main stages. In the first stage, the impulsive velocity due to the interaction of shock wave and structure is determined by using Taylor's fluid-structure interaction (FSI) formulation while supposing a negligible structural deformation. Transmission of shock waves through the thickness of the plate is considered by assuming the material under uniaxial strain. At the end of the first stage, cavita-tion is supposed to occur all over the plate. In the second stage, deformation of the plate will commence which is followed by the collapse of the cavitation zone. The corresponding mechanical response of the plate is determined by imposing a simply-supported boundary conditions and by applying Lagrangian Energy approach to derive the motion equation, taking into account the water inertial effects. The proposed method is then tested with isotropic (steel) and laminated composite (carbon-fiber/epoxy) plates to analyze for both impulsive velocity and UNDEX responses. The obtained analytical results are compared with those from non-linear finite element explicit code, LS-DYNA. Finally, the advantages and limitations of the present method are evaluated

Construction of a Ultrananocrystalline Diamond Based Cold Cathode Arrays for a Flat-Panel X-Ray Source

A novel cold cathode field emission array (FEA) X-ray source based on ultra-nanocrystalline diamond (UNCD) field emitters is being constructed as an alternative for detection of obscured objects and material. Depending on the geometry of the given situation the flat-panel X-ray source could be used in tomography, radiography, or tomosynthesis. Furthermore, the unit could be used as a portable X-ray scanner or an integral part of an existing detection system. UNCD field emitters show great field emission output and can be deposited over large areas as the case with carbon nanotube forest (CNT) cathodes. Furthermore, UNCDs have better mechanical and thermal properties as compared to CNT tips which further extend the lifetime of UNCD based FEA. This work includes the first generation of the UNCD based FEA prototype which is being manufactured at the Center for Nanoscale Materials within Argonne National Laboratory with standard microfabrication techniques. The prototype is a 3x3 pixel FEA, with a pixel pitch of 500 ?m, where each pixel is individually controllable