A relation between algebraic and transform-based reconstruction technique in computed tomography

In this contribution a coherent relation between the algebraic and the transform-based reconstruction technique for computed tomography is introduced using the mathematical means of two-dimensional signal processing. There are two advantages arising from that approach. First, the algebraic reconstruction technique can now be used efficiently regarding memory usage without considerations concerning the handling of large sparse matrices. Second, the relation grants a more intuitive understanding as to the convergence characteristics of the iterative method. Besides the gain in theoretical insight these advantages offer new possibilities for application-specific fine tuning of reconstruction techniques

Automatic focus algorithms for TDI X-Ray image reconstruction

In food industry, most products are checked by X-rays for contaminations. These X-ray machines continuously scan the product passing through. To minimize the required X-ray power, a Time, Delay and Integration (TDI) CCD-sensor is used to capture the image. While the product moves across the sensor area, the X-ray angle changes during the pass. As a countermeasure, adjusting the sensor shift speed on a single focal plane of the product can be selected. However, the changing angle result in a blurred image in dependance to the thickness of the product. This so-called ''laminographic effect'' can be compensated individually for one plane by inverse filtering. As the plane of contamination is unknown, the blurred image will be inversely filtered for different planes, but only one of these images shows the correctly focussed object. If the correct image can be found, the plane containing the contamination is identified. In this contribution we demonstrate how the correctly focussed images can be found by analyzing the images of all planes. Different characteristics for correctly and incorrectly focussed planes like sharpness, number of objects and edges are investigated by using image processing algorithms

Antegrade Endobiliary Forceps Biopsy Improves Diagnosis of Klatskin Tumor Compared to Brush Biopsy

Aim. To evaluate the safety and accuracy of percutaneous transhepatic biliary biopsy in patients with suspected Klatskin tumor.Materials and methods. Between 2013–2020, percutaneous transhepatic biliary drainage (PTBD) was performed in 52 patients with Klatskin tumor, complicated by obstructive jaundice. After successful PTBD, the diagnosis was verified by antegrade access. 74 procedures were performed: brush (n = 36; 48.6 %) or forceps biopsies (n = 38; 51.4 %).Results. There were no adverse events associated with a brush biopsy. Only grade I complications were after the forceps technique: 3 patients (7.9 %) developed hemobilia, which was corrected conservatively. Malignant lesions of the biliary tract were detected by forceps technique in 79.0 %, brush biopsy in 66.7 % (p >0,05). The degree of tumor differentiation was determined in 60.0 % (n = 18) vs 12.5 % (n = 3) (p < 0,01), respectively.Sensitivity and specificity of forceps biopsy were slightly higher than in brush: 82.4 % and 75.0 % vs 73.3 % and 66.7 % (p >0,05).Conclusions. Antegrade percutaneous transhepatic biliary biopsy is safe for both brush and forceps techniques. However, forceps biopsy has higher sensitivity and specificity in the diagnosis Klatskin tumor and better possibility of determining the degree of malignancy differentiation

A Midsummer Night's Dream

A simple, economic, highly sensitive and highly selective method for the detection of caffeine has been developed at bare and Nafion-modified glassy carbon electrodes (GCE). The electrochemical behaviour of caffeine was examined in electrolyte solutions of phosphate buffer saline, sodium perchlorate, and in choline chloride plus oxalic acid, using analytical determinations by fixed potential amperometry, phosphate buffer saline being the best. Modifications of the GCE surface with poly(3,4-ethylenedioxythiophene) (PEDOT), Nafion, and multi-walled carbon nanotubes were tested in order to evaluate possible sensor performance enhancements, Nafion giving the most satisfactory results. The effect of interfering compounds usually found in samples containing caffeine was examined at GCE without and with Nafion coating, to exclude interferences, and the sensors were successfully applied to determine the caffeine content in commercial beverages and drugs

(Per)chlorate reduction by an acetogenic bacterium, Sporomusa sp., isolated from an underground gas storage

A mesophilic bacterium, strain An4, was isolated from an underground gas storage reservoir with methanol as substrate and perchlorate as electron acceptor. Cells were Gram-negative, spore-forming, straight to curved rods, 0.5–0.8 μm in diameter, and 2–8 μm in length, growing as single cells or in pairs. The cells grew optimally at 37°C, and the pH optimum was around 7. Strain An4 converted various alcohols, organic acids, fructose, acetoin, and H2/CO2 to acetate, usually as the only product. Succinate was decarboxylated to propionate. The isolate was able to respire with (per)chlorate, nitrate, and CO2. The G+C content of the DNA was 42.6 mol%. Based on the 16S rRNA gene sequence analysis, strain An4 was most closely related to Sporomusa ovata (98% similarity). The bacterium reduced perchlorate and chlorate completely to chloride. Key enzymes, perchlorate reductase and chlorite dismutase, were detected in cell-free extracts

Immobilization, Trapping, and Anion Exchange of Perrhenate Ion Using Copper-Based Tripodal Complexes

We describe a multidentate tripodal ligand in which three pendant arms carrying di(2-picolyl)amine units are linked to the ortho positions of a tris(o-xylyl) scaffold, providing N(CH[subscript 2]-o-C[subscript 6]H[subscript 4]CH[subscript 2]N(CH2py)[subscript 2])[subscript 3] (L). Reaction of L with CuCl[subscript 2] in the presence of hexafluorophosphate anion afforded blue cubes of [(CuCl)[subscript 3]L](PF[subscript 6])[subscript 3]·5H[subscript 2]O (1). Crystallographic studies of 1 revealed that the three symmetry-related arms each coordinate a {Cu[superscript II]Cl} unit, and two molecules of 1 are connected to one another through a Cu(μ-Cl)[subscript 2]Cu bridge, extending the molecular structure to form a two-dimensional (2-D) layer. These 2-D layers pack in an ABCABC... fashion with PF[subscript 6]– anions located in between. Reaction of 1 with a stoichiometric amount of perrhenate ion afforded blue plates of [(CuCl)[subscript 3]L](PF[subscript 6])(ReO[subscript 4])[subscript 2]·3H[subscript 2]O (2). Compound 2 has the same lattice structure as 1, but the tricopper unit backbone now traps one ReO[subscript 4]– anion through Coulombic interactions. In addition, three molecules of 2 are bridged by a perrhenate ion, forming a Cu[subscript 3](μ[superscript 3]-ReO[subscript 4]) cluster, to give a different 2-D structure displaying a rare tridentate bridging ReO[subscript 4]– mode. Thus, in addition to classic perrhenate trapping through weak Coulombic interactions, 2 represents an exceptional example in which the ReO[subscript 4]– anion is immobilized in an extended framework through tight covalent interactions. The interlamellar PF[subscript 6]– anions in 1 can be exchanged with other anions including perrhenate, perchlorate, or periodate. The structural similarity between perrhenate and pertechnetate makes these materials of potential interest for pertechnetate trapping

Behavioral response of dissimilatory perchlorate-reducing bacteria to different electron acceptors

The response behavior of three dissimilatory perchlorate-reducing bacteria to different electron acceptors (nitrate, chlorate, and perchlorate) was investigated with two different assays. The observed response was species-specific, dependent on the prior growth conditions, and was inhibited by oxygen. We observed attraction toward nitrate when Dechloromonas aromatica strain RCB and Azospira suillum strain PS were grown with nitrate. When D. aromatica and Dechloromonas agitata strain CKB were grown with perchlorate, both responded to nitrate, chlorate, and perchlorate. When A. suillum was grown with perchlorate, the organism responded to chlorate and perchlorate but not nitrate. A gene replacement mutant in the perchlorate reductase subunit (pcrA) of D. aromatica resulted in a loss of the attraction response toward perchlorate but had no impact on the nitrate response. Washed-cell suspension studies revealed that the perchlorate grown cells of D. aromatica reduced both perchlorate and nitrate, while A. suillum cells reduced perchlorate only. Based on these observations, energy taxis was proposed as the underlying mechanism for the responses to (per)chlorate by D. aromatica. To the best of our knowledge, this study represents the first investigation of the response behavior of perchlorate-reducing bacteria to environmental stimuli. It clearly demonstrates attraction toward chlorine oxyanions and the unique ability of these organisms to distinguish structurally analogous compounds, nitrate, chlorate, and perchlorate and respond accordingly