Self-assembled magnetic bead biosensor for measuring bacterial growth and antimicrobial susceptibility testing

Bacterial antibiotic resistance is one of the major concerns of modern healthcare worldwide, and the development of rapid, growth-based, antimicrobial susceptibility tests is key for addressing it. The cover image shows a self-assembled asynchronous magnetic bead rotation (AMBR) biosensor developed for rapid detection of bacterial growth. Using the biosensors, the minimum inhibitory concentration of a clinical E. coli isolate can be measured within two hours, where currently tests take 6-24 hours. A 16-well prototype is also constructed for simple and robust observation of the self-assembled AMBR biosensors.     

Measurement of the trapping efficiency of an elliptical optical trap with rigid and elastic objects

Optical tweezers and their various modifications offer a sophisticated way to perform noncontact cell manipulation. In this paper, we quantify forces existing in an elliptical trap formed by two cylindrical lenses and compare the results with a point optical trap case. The trapping efficiency of point and elliptical traps was analyzed by measuring the Q values of both traps. Polystyrene microspheres and red blood cells (RBCs) were used as samples. Stretching of the RBC was taken into account in the Q value measurements. Although the Q value of a point optical trap is larger than that of an elliptical trap when measured for a single RBC, we can manipulate the orientation of an RBC in a point trap with the elliptical trap and can also trap several RBCs simultaneously in the elliptical trap far from the cuvette surfaces by using a long-working-distance water immersion objective. This opens new possibilities for studying light-matter interactions at the cellular level.     

Evaluation of Substituted 1,2,3‐Dithiazoles as Inhibitors of the Feline Immunodeficiency Virus (FIV) Nucleocapsid Protein via a Proposed Zinc Ejection Mechanism

A diverse library of 5‐thieno‐, 5‐oxo‐, and 5‐imino‐1,2,3‐dithiazole derivatives was synthesized and evaluated for efficacy against the feline immunodeficiency virus (FIV) as a model for HIV in cells. Several diverse compounds from this series displayed nanomolar activity and low toxicity, representing a potential new class of compounds for the treatment of FIV and HIV.     

Modelling and performance evaluation of chromatographic monosaccharide recovery from concentrated acid lignocellulosic hydrolysates

BACKGROUND: Chromatographic fractionation of concentrated acid lignocellulosic hydrolysates was investigated. The goal was to present a model that can be used in designing and performance evaluation of the fractionation process. Simple models were fitted to the experimental sorption data of the main components of the hydrolysates (sulfuric acid, monosaccharides, and acetic acid) on CS16GC resin. A column model which takes into account resin shrinking was derived. RESULTS: Simulation results were found to be in good agreement with the experimental results. The isotherm models predicted correctly the co‐operative effect of H₂SO₄ on the sorption of the other adsorbates. The effect of column loading on the productivity of the separation process was studied with simulations. With 20 wt% H₂SO₄, the highest productivity was obtained with 11.5 vol% column loading. In addition, a process consisting of concentrated acid lignocellulose hydrolysis, batchwise chromatographic separation, and H₂SO₄ recycling was investigated. With the recycling, the maximum productivity was obtained with 18.2 vol% column loading. CONCLUSIONS: It was demonstrated that the entire reactor‐separation process with internal recycling must be considered when evaluating the performance of the monosaccharide‐acid separation step. Process performance was found to decrease with increasing feed concentration of sulfuric acid. Copyright © 2012 Society of Chemical Industry     

Do individual coping strategies help or harm in the work–family conflict situation? Examining coping as a moderator between work–family conflict and well-being.

In this study we examined the moderator role of coping (problem-, emotion-, and avoidance-focused coping strategies) between work-to-family and family-to-work conflict and well-being (work engagement, job satisfaction, and family satisfaction). The study was based on a sample of 527 Finnish workers. Hierarchical moderated regression analyses showed that emotion-focused coping buffered against job dissatisfaction in a high family-to-work conflict situation. On the other hand, emotion-focused coping was harmful for family satisfaction in the same stressful situation: Those who used more emotion-focused coping were less satisfied with their family life under the conditions of high family-to-work conflict. Furthermore, avoidance coping was beneficial in a high family-to-work conflict situation: Those who used more avoidance coping were more satisfied with their family life in this situation. No buffering effects were found for work engagement or for problem-focused coping. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Transition-Edge Sensors for Particle Induced X-ray Emission Measurements

In this paper we present a new measurement setup, where a transition-edge sensor detector array is used to detect X-rays in particle induced X-ray emission (PIXE) measurements with a 2 MeV proton beam. Transition-edge sensors offer orders of magnitude improvement in energy resolution compared to conventional silicon or germanium detectors, making it possible to recognize spectral lines in materials analysis that have previously been impossible to resolve, and to get chemical information from the elements. Our sensors are cooled to the operation temperature ( \(\sim \) 65 mK) with a cryogen-free adiabatic demagnetization refrigerator, which houses a specially designed X-ray snout that has a vacuum tight window to couple in the radiation. For the best pixel, the measured instrumental energy resolution was 3.06 eV full width at half maximum at 5.9 keV. We discuss the current status of the project, benefits of transition-edge sensors when used in PIXE spectroscopy, and the results from the first measurements.     

Morphological Family Size in a Morphologically Rich Language: The Case of Finnish Compared With Dutch and Hebrew.

Finnish has a very productive morphology in which a stem can give rise to several thousand words. This study presents a visual lexical decision experiment addressing the processing consequences of the huge productivity of Finnish morphology. The authors observed that in Finnish words with larger morphological families elicited shorter response latencies. However, in contrast to Dutch and Hebrew, it is not the complete morphological family of a complex Finnish word that codetermines response latencies but only the subset of words directly derived from the complex word itself. Comparisons with parallel experiments using translation equivalents in Dutch and Hebrew showed substantial cross-language predictivity of family size between Finnish and Dutch but not between Finnish and Hebrew, reflecting the different ways in which the Hebrew and Finnish morphological systems contribute to the semantic organization of concepts in the mental lexicon. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sphingomyelinase induces lipid microdomain formation in a fluid phosphatidylcholine/sphingomyelin membrane

The behaviors of two chemically well-defined sphingolipids, N-palmitoyl-sphingomyelin (C16:0-SM) and the corresponding ceramide (C16:0-Cer), in a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) matrix were compared. Minor attenuation of lateral diffusion upon increasing the mole fraction of C16:0-SM (XSM, up to 0.25) was indicated by the slight decrement in the excimer/monomer intensity ratio (Ie/Im) for a trace amount (mole fraction X = 0.01) of a pyrene-labeled ceramide analogue (N-[(pyren)-1-yl]decanoyl-sphingosine, PDCer) in keeping with the miscibility of C16:0-SM in POPC. Increasing membrane order was revealed by the augmented polarization P for diphenylhexatriene (DPH). In contrast, when C16:0-Cer was substituted for C16:0-SM an approximately 1.6-fold increase in Ie/Im for PDCer was evident upon increasing Xcer, with parallel increment in DPH polarization. In agreement with our recent data on natural ceramides in dimyristoylphosphatidylcholine (DMPC) bilayers [Holopainen et al. (1997) Chem. Phys. Lipids 88, 1-13], we conclude that C16:0-Cer becomes enriched into microdomains in the fluid POPC membrane. Interestingly, enhanced formation of microdomains by ceramide was observed when the total sphingolipid content in tertiary alloys with POPC was maintained constant (Xcer + XSM = 0.25) and the SM/Cer stoichiometry was varied. Finally, when ceramide was generated enzymatically in POPC/C16:0-SM (3:1, molar fraction) LUVs by sphingomyelinase (SMase, Bacillus cereus), maximally approximately 85% of hydrolysis of sphingomyelin was measured within <3 min at 30 degreesC. The formation of ceramide was accompanied by a closely parallel increase in DPH polarization. There was also an increase in Ie/Im for PDCer; however, these changes in Ie/Im were significantly slower, requiring approximately 105 min to reach a steady state. These data show that the rapid enzymatic formation of ceramide under these conditions is followed by much slower reorganization process, resulting in the formation of microdomains enriched in this lipid.     

The Effect of SO2 and H2O on the Activity of Pd/CeO2 and Pd/Zr–CeO2 Diesel Oxidation Catalysts

Pd/CeO₂ and Pd/Zr-CeO₂ diesel oxidation catalysts were treated with sulphur, sulphur–water and water. According to the BET, TEM-EDS, XPS, ICP-OES analyses and catalytic activity tests, both studied catalysts were deactivated by sulphur due to formation of sulphates. Water treatment was found to have a promoting effect on the oxidation of CO and C₃H₆.