Microbial susceptibility of various polymers and evaluation of thermoplastic elastomers with antimicrobial additives

The incursion of microbial growth on polymeric products can deteriorate their performance and lead to the development of undesirable staining and odors. A growing trend in the industry has aimed to reduce microbial populations on high-touch surfaces via the use of antimicrobials to protect material aesthetics and durability or to prevent the spread of pathogenic microorganisms. In this study, a variety of plastic substrates (30 unique polymer compounds), including poly(acrylonitrile-co-butadiene-co-styrene), poly(butylene terephthalate), poly(etherimide), various thermoplastic elastomers (TPEs), poly(carbonates), and poly(amides), were screened for susceptibility to microbial attack using American Society for Testing and Materials (ASTM) G21 (fungi susceptibility), Japanese Industrial Standard (JIS) Z2801, and modified ASTM E1428-15a (bacterial susceptibility) test standards. TPEs were determined to be most susceptible to microbial attack under the appropriate environmental conditions. Subsequent studies assessed the use of an antimicrobial additive, zinc pyrithione (ZPT), for potential efficacy in a variety of TPE blends for diverse target market applications. ZPT proved to be very effective in protecting TPEs, reducing Staphylococcus aureus and Escherichia coli populations by 99.9% or more in JIS Z2801 testing and inhibiting fungal growth (rating = 0) according to the ASTM G21 standard.     

Flüssig/Flüssig‐Extraktion von Indium aus sauren Lösungen

The extraction of indium from a synthetic sulfate‐containing solution using commercial reagents (Cyanex 272, DEHPA, and Cyanex 923) is evaluated on a comparative basis. The extraction profiles of indium (III) were examined with regard to the reagent concentration, the pH value of the aqueous solution, and the indium concentration in a low phase ratio of 1:10. DEHPA and Cyanex 272 are, in contrast to Cyanex 923, very well suited for the extraction of indium. Re‐extraction with HCl and H₂SO₄ is compared.     

Evaluation of three pose estimation algorithms for model-based roentgen stereophotogrammetric analysis

Model-based roentgen stereophotogrammetric analysis (RSA) uses a three-dimensional surface model of an implant in order to estimate accurately the pose of that implant from a stereo pair of roentgen images. The technique is based on minimization of the difference between the actually projected contour of an implant and the virtually projected contour of a model of that same implant. The advantage of model-based RSA over conventional marker-based RSA is that it is not necessary to attach markers to the implant. In this paper, three pose estimation algorithms for model-based RSA are evaluated. The algorithms were assessed on the basis of their sensitivities to noise in the actual contour, to the amount of drop-outs in the actual contour, to the number of points in the actual contour and to shrinkage or expansion of the actual contour. The algorithms that were studied are the iterative inverse perspective matching (IIPM) algorithm, an algorithm based on minimization of the difference (DIF) between the actual contour and the virtual contour, and an algorithm based on minimization of the non-overlapping area (NOA) between the actual and virtual contour. The results of the simulation and phantom experiments show that the NOA algorithm does not fulfil the high accuracy that is necessary for model-based RSA. The IIPM and DIF algorithms are robust to the different distortions, making model-based RSA a possible replacement for marker-based RSA.     

Heart rate during development in the turtle embryo: effect of temperature

Growth and development can occur over a wide range of physical conditions in reptiles. Cardiovascular function must be critical to this ability. However, information on cardiovascular function in developing reptiles is lacking. Previous work indicated that in reptiles the effects of temperature on growth and metabolism are largely restricted to early development. This study examined whether the previously observed effects of temperature and different perinatal patterns of metabolism observed in amniotic vertebrates are correlated with cardiovascular function. Embryonic and hatchling carcass mass, heart mass and heart rate (HR) were compared for snapping turtle eggs (Chelydra serpentina) incubated at 24 degrees and 29 degrees C. Incubation time was shorter at 29 degrees C (56.2 days) than at 24 degrees C (71.1 days). Carcass and heart growth showed a sigmoidal pattern at both temperatures. However, cardiac growth showed a relative decrease as incubation proceeded. Incubation temperature significantly affected the HR pattern during development. The HR of embryos incubated at 24 degrees C was constant for most of incubation (51.8 +/- 4.8 min-1). A small decrease was observed just prior to and a large decrease immediately following hatching (posthatch, 22.3 +/- 4.1 min-1). At 29 degrees C embryonic HR was greater than at 24 degrees C early in development (72.3 +/- 3 min-1). The HR steadily decreased to values equivalent to those at 24 degrees C. The HRs of 24 degrees C and 29 degrees C hatchlings were not different. Cardiac output (estimated as the product of heart mass and HR) increased rapidly during early development and then slowed dramatically at both temperatures. These data are consistent with the suggestion that temperature exerts its effects primarily early in development. Furthermore, the changes in cardiovascular function are correlated with metabolic changes in hatching vertebrates.     

MR of the heart under pharmacologic stress

Magnetic resonance imaging is one method for assessing cardiac function and perfusion at rest and under stress conditions. In this article, the potential of stress magnetic resonance imaging for evaluating ischemic heart disease is reviewed, and technical aspects of some developments that may contribute to comprehensive magnetic resonance imaging assessment of heart disease under rest and stress are discussed.     

Intrathecal synthesis of immunoglobulins in eosinophilic meningoencephalitis due to Angiostrongylus cantonensis

Eosinophilic meningoencephalitis due to the nematode Angiostrongylus cantonensis, which is endemic to Cuba, occurs in children and is due to accidental contact with soil snails. The course is less often fatal than in adult patients in southeastern Asia. Cerebrospinal fluid (CSF) and serum samples from 24 pediatric patients were analyzed and evaluated in CSF/serum quotient diagrams (Reiber graphs) to characterize the neuroimmunological response and the blood-CSF barrier dysfunction that occur in the course of the disease. At the time of the first diagnostic lumbar puncture, together with eosinophilic pleocytosis (1,920 +/- 400 cells/microl), intermediate blood-CSF barrier dysfunction (i.e., an increased CSF/serum albumin quotient) with no intrathecal immunoglobulin G (IgG), IgA, and IgM class response was observed in all cases. Seven days later, at the time of early clinical recovery, the blood-CSF barrier dysfunction was normalized in 75% of the patients, but meanwhile, intrathecal immunoglobulin synthesis emerged in all cases, as either a two-class response (IgG and IgA in 85% of the patients) or a three-class response (IgG, IgA, and IgM; 30%). The fraction of eosinophilic cells (40%) remained large despite a decreasing total cell count. The neuroimmunological pattern of this inflammatory response to the parasite and its toxins is discussed with regard to the CSF patterns of other infectious diseases caused by bacteria or viruses.     

On the statistical modelling of coronary arteriographic data: dynamics of coronary atherosclerosis related to systemic and focal parameters. REGRESS Study Group. Regression Growth Evaluation Statin Study

Existing methods to analyse data from repeated arteriographic progression/regression studies are restrictive and do not fully explore the dynamics of coronary artherosclerosis. We present a new approach making a distinction between new occlusions, new lesions, and growth of existing lesions. Random effect models, based on the logistic, the Poisson, and the normal distribution are proposed with correlation depending on distance. The data from the Regression Growth Evaluation Statin Study (REGRESS) are used to validate the model. Lipid lowering treatment of pravastatin resulted in less growth of existing lesions and fewer new lesions than when placebo was given. Fewer new lesions were found in segments influenced by percutaneous transluminal coronary angioplasty (PTCA) than in segments not influenced by PTCA. Similarly, the growth of lesions influenced by PTCA was smaller than lesions not influenced by PTCA. More new occlusions were found in segments influenced by coronary arterial bypass grafting (CABG) than in segments not influenced by CABG, but 98 per cent of the new occlusions were located proximal to the bypass anastomosis. Similarly, existing lesions proximal to the bypass anastomosis showed larger growth (p < 0.001). We conclude that our new approach for analysing the arteriographic data from repeated coronary arteriographic studies appeared a fruitful way to analyse the dynamics of coronary atherosclerosis.     

Multi-agent segmentation of IVUS images

A novel multi-agent image interpretation system has been developed which is markedly different from previous approaches in especially its elaborate high-level knowledge-based control over low-level image segmentation algorithms. Agents dynamically adapt segmentation algorithms based on knowledge about global constraints, contextual knowledge, local image information and personal beliefs. Generally agent control allows the underlying segmentation algorithms to be simpler and be applied to a wider range of problems with a higher reliability.The agent knowledge model is general and modular to support easy construction and addition of agents to any image processing task. Each agent in the system is further responsible for one type of high-level object and cooperates with other agents to come to a consistent overall image interpretation. Cooperation involves communicating hypotheses and resolving conflicts between the interpretations of individual agents.The system has been applied to IntraVascular UltraSound (IVUS) images which are segmented by five agents, specialized in lumen, vessel, calcified-plaque, shadow and sidebranch detection. IVUS image sequences from 7 patients were processed and vessel and lumen contours were detected fully automatically. These were compared with expert-corrected semiautomatically detected contours. Results show good correlations between agents and expert with r=0.84 for the lumen and r=0.92 for the vessel cross-sectional areas, respectively.