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Selective transarterial catheterisation and translumbar sac puncture are well established techniques for the management of significant type 2 endoleaks. We report an additional technique for endovascular access to the endoleak sac through the space between the iliac endograft and artery wall.
PurposeTo investigate the feasibility of percutaneous gallbladder cryoablation (GBC) under CT guidance in a swine model with histopathologic correlation.Materials and MethodsInstitutional Animal Care and Use Committee approval was obtained for this study protocol. Five pigs underwent GBC. Under CT guidance, 3–4 cryoprobes were positioned percutaneously at the gallbladder margins. Thermocouple probes were placed percutaneously at the gallbladder fundus, neck, free wall, and gallbladder fossa. Two freeze–thaw cycles ranging from 10 to 26 min were performed. The subjects were sacrificed 5 h after cryoablation. The gallbladder and bile ducts were resected, stained, and examined microscopically.ResultsGBC was completed in all subjects. A 10-mm ablation margin was achieved beyond all gallbladder walls. Thermocouple probes reached at least −20 °C. Intra-procedural body temperature decreased to a minimum of 35 °C but recovered after the procedure. Intra- and post-procedural vital signs otherwise remained within physiologic parameters. Non-target ablation occurred in the stomach and colon of the first two subjects. Histology demonstrated complete denudation of the gallbladder epithelium, hemorrhage, and edema within the muscularis layer, and preservation of the microscopic architecture of the common bile duct in all cases.ConclusionPercutaneous gallbladder cryoablation is feasible, with adequate ablation margins obtained and histologic changes demonstrating transmural necrosis. Adjacent structures included in the ablation may require conservative ablation zones, hydrodissection, or continuous saline lavage.
PurposeTo prospectively assess discontinuation of indwelling bladder catheterization (IBC) and relief of lower urinary tract symptoms (LUTS) due to benign prostatic hyperplasia (BPH) following prostate artery embolization (PAE) in poor surgical candidates.MethodsPatients ineligible for surgical intervention were offered PAE after at least 1 month of IBC for management of urinary retention secondary to BPH; exclusion criteria for PAE included eligibility for surgery, active bladder cancer or known prostate cancer. Embolization technical and clinical success were defined as bilateral prostate embolization and removal of IBC, respectively. Patients were followed for at least 6 months and evaluated for International Prostate Symptom Score, quality of life, prostate size and uroflowmetric parameters.ResultsA total of 43 patients were enrolled; bilateral embolization was performed in 33 (76.7%), unilateral embolization was performed in 8 (18.6%), and two patients could not be embolized due to tortuous and atherosclerotic pelvic vasculature (4.7%). Among the patients who were embolized, mean prostate size decreased from 75.6 ± 33.2 to 63.0 ± 23.2 g (sign rank p = 0.0001, mean reduction of 19.6 ± 17.3%), and IBC removal was achieved in 33 patients (80.5%). Clavien II complications were reported in nine patients (21.9%) and included urinary tract infection (three patients, 7.3%) and recurrent acute urinary retention (six patients, 14.6%). Nine patients (22.0%) experienced post-embolization syndrome.ConclusionsPAE is a safe and feasible for the relief of LUTS and IBC in highly comorbid patients without surgical treatment options.
Background: Renal patients with a tunnelled haemodialysis line are at risk of fibrin ‘sheath’ formation which can lead to occlusion. Dysfunctional lines are best treated by catheter exchange with a new subcutaneous tunnel; however, there is a risk of scarring, venous stenosis, potential loss of valuable access as well as the risk of infection. Method: We report a retrospective review of our experience using tunnelled line intraluminal plasty (TuLIP) in 11 patients over 16 months with fibrin sheath formation on pre-existing tunnelled haemodialysis catheters. Result: All patients responded well to treatment with median line patency post TuLIP reaching 112 days. Conclusion: TuLIP may have a role in extending catheter lifespan and delaying more invasive intervention.
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A novel sensitive method for detection of DNA methylation was developed with thioglycollic acid (TGA)-capped CdTe quantum dots (QDs) as fluorescence probes. Recognition of methylated DNA sites would be useful strategy due to the important roles of methylation in disease occurrence and developmental processes. DNA methylation occurs most often at cytosine-guanine sites (CpG dinucleotides) of gene promoters. The QDs significantly interacted with hybridized unmethylated and methylated DNA. The interaction of CpG rich methylated and unmethylated DNA hybrid with quantum dots as an optical probe has been investigated by fluorescence spectroscopy and electrophoresis assay. The fluorescence intensity of QDs was highly dependent to unmethylated and methylated DNA. Specific site of CpG islands of Adenomatous polyposis coli (APC), a well-studied tumor suppressor gene, was used as the detection target. Under optimum conditions, upon the addition of unmethylated dsDNA, the fluorescence intensity increased in linear range from 1.0 × 10{sup − 10} to 1.0 × 10{sup − 6}M with detection limit of 6.2 × 10{sup − 11} M and on the other hand, the intensity of QDs showed no changes with addition of methylated dsDNA. We also demonstrated that the unmethylated and methylated DNA and QDs complexes showed different mobility in electrophoresis assay. This easy and reliable method could distinguish between methylated and unmethylated DNA sequences.
The present work provides extensive insight into the newly developed sustainable bio-resin (terpene) functionalized Natural Rubber (NR). Structural elucidation of the functionalized NR was established by proton nuclear magnetic resonance ({sup 1}H NMR) and Fourier transform infrared spectroscopy (FTIR) respectively. This study demonstrates the effect of Bio-Resin Functionalized NR (BR-NR)/Epoxidized Natural rubber (ENR) blends combined with four different specific surface areas of highly dispersible silica (HDS). The primary aim of these analyses is the description of the interfacial area on the HDS surface involved in physical form (Micro pearl and Granule) and synergistic rubber-filler interaction mechanism for the superior reinforcement. Improved state of HDS dispersion has been achieved in absence of conventional toxic processing oil, silane coupling agent and normal zinc oxide. Remarkable improvement in overall properties corroborated with various meticulous characterization including cure characteristics, bound rubber content, Mullins effect and physico-mechanical properties etc. An augmented rubber-filler interaction is also supported by micro computed tomography morphology study. Dynamic mechanical analysis shows an ultra-low rolling resistance coupled with high traction and advanced elastic response of the greener macromolecules. More decisively, the macromolecule system toned up sparingly in the presence of the bio-resin. Newly developed BR-NR together with ENR 25 and their significant contribution to the improvements of properties are schematically explained.
As an important metric to tell if a nonlinear dynamic system has a singular attractor or divergent trajectory, the maximal Lyapunov exponent (MLE) can be calculated from either system models or time series of state variable measurement. However, in the real world, due to inaccurate models, measurement noise, and the fact that sometimes state variables cannot be measured directly, it is very difficult to get an accurate MLE, which limits its application in, for example, in prediction of a nonlinear physical system (e. g. power systems, etc.) behavior. To overcome these factors, this paper proposed a trajectory-estimation-based MLE calculation approach. The proposed approach addressed how to calculate the MLE when state variables cannot be accessed directly, and uncertainties in system models, as well as noise in measurements. The simulation results shows that the proposed approach is able to handle well the nonlinear measurement functions between state variables and measurements, and get better results than pure model-based approaches or measurement-based approaches in front of measurement noise and model uncertainties.
low-temperature synthesis of saturated fatty acid esters with aliphatic alcohols by enzymatic esterification in the presence of heterogeneous biоcatalysts was suggested. The biоcatalysts were prepared by immobilization of recombinant rPichia/lip lipase on mesoporous silica. A comparison of the reaction rates was used to make up a matrix of biоcatalyst activities and determine a pair of acid/alcohol substrates, for which a maximum esterification rate was observed. A high activity of biоcatalysts was observed in the esterification of fatty acids with seven or more carbon atoms in the molecule. The rate of esterification of fatty acids with primary alcohols (n-C{sub 3}—C{sub 16} or iso-С{sub 5}) was two orders of magnitude higher than that with secondary alcohols (sec-С{sub 3}—С{sub 4}). The silica-immobilized rPichia/lip lipase possessed a high operational stability; the biocatalyst operated without loss of activity for hun-dreds of hours at 18—22 °С in a non-traditional for enzymes medium of organic solvents.
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For better application of numerical simulation in optimization and design of friction stir welding (FSW), this paper presents a new frictional boundary condition at the tool/workpiece interface for computational fluid dynamics (CFD) modeling of FSW. The proposed boundary condition is based on an implementation of the Coulomb friction model. Using the new boundary condition, the CFD simulation yields non-uniform distribution of contact state over the tool/workpiece interface, as validated by the experimental weld macrostructure. It is found that interfacial sticking state is present over large area at the tool-workpiece interface, while significant interfacial sliding occurs at the shoulder periphery, the lower part of pin side, and the periphery of pin bottom. Due to the interfacial sticking, a rotating flow zone is found under the shoulder, in which fast circular motion occurs. The diameter of the rotating flow zone is smaller than the shoulder diameter, which is attributed to the presence of the interfacial sliding at the shoulder periphery. For the simulated welding condition, the heat generation due to friction and plastic deformation makes up 54.4 and 45.6% of the total heat generation rate, respectively. In conclusion, the simulated temperature field is validated by the good agreement to the experimental measurements.
The process of cyclic bending was investigated using thin sheets of the magnesium alloy AZ31 and α-titanium. These materials possess an hcp crystal lattice with different c/a ratios. It turned out that the latter have a substantial influence on the sheet deformation behavior. Even for small deformations (up to 2% strain), a large influence on the yield stress was present for both materials. In addition, cyclic bending contributes to the activation of prismatic slip, which is accompanied by twinning and detwinning. The changes in sheet anisotropy following cyclic bending were determined using texture measurements. Specifically, the AZ31 alloy sheets exhibited a considerable change in anisotropy of the mechanical properties with an increasing number of bending cycles. The anisotropy in the yield stress increases from 15% in the initial condition to 40% after three cycles. For the α-titanium sheet, the change in anisotropy was approx. 26% less. In general, the largest changes in properties occurred already in the first bending cycle and a stabilization took place upon further cycling.
The combination of chromium-free passivation and nano-electrodeposition was reported to replace chromic acid passivation for electrogalvanized steel. The microstructure, corrosion resistance, scratch resistance and wear resistance of nanocrystalline zinc coating after chromium-free passivation were investigated. It was demonstrated that the nanocrystalline zinc coating after chromium-free passivation mainly consists of ZnO, Zn{sub 3}(PO{sub 4}){sub 2}, Ti{sub 2}O{sub 3} and/or (Zn(OH){sub 2}, ZnHPO{sub 4} and TiO{sub 2}), which possesses better comprehensive properties than conventional coarse-grained zinc coating after commercial trivalent chromium passivation. The reason was also discussed in detail.
Creep-resistant 9Cr steels are extremely important in thermal power generation industry due to their marked resistance to creep and corrosion. The weldability of these alloys is critical since they are used in welded construction equipment. The required mechanical properties are achieved after post-weld heat treatment. This study examined the effect of different post-weld heat treatments on microstructure and mechanical properties of creep strength-enhanced 9Cr steel welding deposits. It was obtained with an experimental flux-cored arc welding wire used under protective gas (Ar-20% CO{sub 2}). The heat treatments used were: (1) tempering (760 °C × 2 h), (2) solubilizing (1050 °C × 1 h) + tempering (760 °C × 2 h) and (3) solubilizing (1150 °C × 1 h) + first tempering (660 °C × 3 h) + second tempering (660 °C × 3 h). All-weld metal chemical composition was analyzed, and hot tensile tests were carried out at different temperatures. Charpy-V impact tests and Vickers microhardness measurements were also performed. Microstructures were studied using x-ray diffraction and optical and scanning electron microscopy. In all cases, a martensitic matrix with intergranular and intra-granular precipitates was detected. In the as-welded condition, δ-ferrite was also found. Microhardness dropped, and the impact energy increased with post-weld heat treatments. The highest hot tensile strength result was achieved with samples submitted to austenization at 1150 °C and double tempering at 660 °C.
An H 13 (high-strength, low-ductility) tool steel die will fail due to compressive high cycle fatigue. If the die is manufactured by direct metal deposition and layered with Inconel-718 (low-strength, high-ductility), it may impact the mechanical properties of the material. Hardness tests, micro-tensile tests, and micro-compression tests were used to analyze the mechanical properties of this additive manufactured layered metal while observing real-time morphology changes on the surface. Energy dispersive spectroscopy was also performed to determine where failure tended to occur within the Inconel-718 material. The hardness was lower than expected, as was the ultimate tensile strength, yield strength, modulus of elasticity, and strain at failure. Each tensile test failed within the Inconel-718 layer. In conclusion, a sample designed to have a single thin middle layer of Inconel-718 sandwiched by H 13 enabled the visual recording of crack initiation and propagation under a tensile load using a confocal scanning laser microscope.
Background: Coronary artery calcium (CAC) can be used to estimate vascular age in adults, providing a convenient transformation of CAC from Agatston units into a year’s scale. We investigated the role of coronary vascular age in predicting stress-induced myocardial ischemia in subjects with suspected coronary artery disease (CAD). Methods: A total of 717 subjects referred to CAC scoring and {sup 82}Rb PET/CT stress-rest myocardial perfusion imaging for suspected CAD were studied. CAC score was measured according to the Agatston method and coronary vascular age by equating estimated CAD risk for chronological age and CAC using the formula 39.1 + 7.25 × ln(CAC + 1). Results: Stress-induced ischemia was present in 105 (15%) patients. Mean chronological age, CAC score, and coronary vascular age were higher (all P < .001) in patients with ischemia compared to those without. At incremental analysis, the global Chi square increased from 41.26 to 68.77 (P < .001) when chronological age was added to clinical variables. Including vascular age in the model, the global Chi square further increased from 68.77 to 106.38 (P < .001). Adding chronological age to clinical data, continuous net reclassification improvement (cNRI) was 0.57, while adding vascular age to clinical data and chronological age cNRI was 0.62. At decision curve analysis, the model including vascular age was associated with the highest net benefit compared to the model including only clinical data, to the model including chronological age and clinical data, and to a strategy considering that all patients had ischemia. The model including vascular age also showed the largest reduction in false-positive rate without missing any ischemic patients. Conclusions: In subjects with suspected CAD, coronary vascular age is strongly associated with stress-induced ischemia. The communication of a given vascular age would have a superior emotive impact improving observance of therapies and healthier lifestyles.
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