3D Microstructured Carbon Nanotube Electrodes for Trapping and Recording Electrogenic Cells

Electrogenic cells such as cardiomyocytes and neurons rely mainly on electrical signals for intercellular communication. Microelectrode arrays (MEAs) have been developed for long‐term recording of cell signals and stimulation of electrogenic cells under low‐cell‐stress conditions, providing new insights in the behavior of electrogenic cells and the operation of the brain. To date, MEAs are relying on flat or needle‐shaped electrode surfaces, mainly due to limitations in the lithographic processes. This paper relies on a previously reported elasto‐capillary aggregation process to create 3D carbon nanotube (CNT) MEAs. This study shows that CNTs aggregate in well‐shaped structures of similar size as cardiomyocytes are particularly interesting for MEA applications. This is because i) CNT microwells of the right diameter preferentially trap individual cardiomyocytes, which facilitates single cell recording without the need for clamping cells or signal deconvolution, and ii) once the cells are trapped inside of the CNT wells, this 3D CNT structure is used as an electrode surrounding the cell, which increases the cell–electrode contact area. As a result, this study finds that the recorded output voltages increase significantly (more than 200%). This fabrication process paves the way for future study of complex interactions between electrogenic cells and 3D recording electrodes.     

Improving customer retention in financial services using kinship network information

This study investigates the advantage of social network mining in a customer retention context. A company that is able to identify likely churners in an early stage can take appropriate steps to prevent these potential churners from actually churning and subsequently increase profit. Academics and practitioners are constantly trying to optimize their predictive-analytics models by searching for better predictors. The aim of this study is to investigate if, in addition to the conventional sets of variables (socio-demographics, purchase history, etc.), kinship network based variables improve the predictive power of customer retention models. Results show that the predictive power of the churn model can indeed be improved by adding the social network (SNA-) based variables. Including network structure measures (i.e. degree, betweenness centrality and density) increase predictive accuracy, but contextual network based variables turn out to have the highest impact on discriminating churners from non-churners. For the majority of the latter type of network variables, the importance in the model is even higher than the individual level counterpart variable.     

Impact of microbial activities on the mineralogy and performance of column-scale permeable reactive iron barriers operated under two different redox conditions

The present study focuses on the impact of microbial activities on the performance of various long-term operated laboratory-scale permeable reactive barriers. The barriers contained both aquifer and Fe0 compartments and had received either sulfate or iron(III)-EDTA to promote sulfate-reducing and iron(III)-reducing bacteria, respectively. After dismantlement of the compartments after almost 3 years of operation, DNA-based PCR-DGGE analysis revealed the presence of methanogenic, sulfate-reducing, metal-reducing, and denitrifying bacteria within as well as up- and downgradient of the Fe0 matrix. Under all imposed conditions, the main secondary phases were vivianite, siderite, ferrous hydroxy carbonate, and carbonate green rust as found by scanning electron microscopy (SEM) combined with energy dispersive X-ray analysis (EDX), and X-ray diffraction (XRD). Under sulfate-reduction promoting conditions, iron sulfides were formed in addition, resulting in 7 and 10 times higher degradation rates for PCE and TCE, respectively, compared to unreacted iron. These results indicate that the presence of sulfate-reducing bacteria in or around iron barriers and the subsequent formation of iron sulfides might increase the barrier reactivity.     

Low‐Voltage Electro‐Optic Modulation Using Amorphous Polycarbonate Host Material

The selection process leading to the development of a guest–host electro‐optic material based on an amorphous polycarbonate (APC) is described. The optical loss at 1300 nm of this material system is under 2 dB/cm, which is the confidence limit of the slab measurement used. A Mach–Zehnder modulator fabricated using the push–pull poling technique has a low switching voltage (V_π) of 1.2 V.     

Physico-chemical soil attributes under conservation agriculture and integrated soil fertility management

Nutrient Cycling in Agroecosystems - Conservation Agriculture (CA) and Integrated Soil Fertility Management (ISFM) have been promoted in Sub Saharan Africa as a means to improve soil quality. A...     

Conventional and (eco) toxicological assessment of batch partial ozone oxidation and subsequent biological treatment of a tank truck cleaning generated concentrate

This paper compares the treatment efficiencies of direct (pH 7.5) and advanced (pH 11.5) partial ozonation followed by biodegradation for the treatment of tank cleaning wastewater concentrate. Both S_COD and toxicity removal efficiencies are examined and direct ozonation is found to perform better in combined toxicity and S_COD removal. Optimal process performance, i.e. the minimal ozone dosage resulting in a maximal removal of S_COD and toxicity in the final effluent, is reached upon reaction of 500 mg O₃/l for both ozonation processes. This ozone dosage results in 60% S_COD reduction for direct ozonation and 64% S_COD reduction for advanced ozonation. A 79% toxicity reduction was achieved using direct ozonation compared to 53% toxicity reduction for advanced ozonation as measured with the standard Pseudokirchneriella subcapitata algal 72 h growth inhibition test. Short-term methods for biodegradability (respirometry) and toxicity (30 min Vibrio fisheri luminescence inhibition) estimation are evaluated in view of process control. The maximal specific oxygen uptake rate of an activated sludge culture (respirometry) is found to relate to the 5-day biochemical oxygen demand (S_BOD,5) but less to the actual S_COD removal during biodegradation. The 30 min Vibrio fisheri luminescence inhibition test is found to be a good short-term estimator for relative changes in toxicity when compared to the standard P. subcapitata algal 72 h growth inhibition test. The 500 mg O₃/l optimal ozone dosage, as determined from P. subcapitata algal 72 h growth inhibition and S_COD removal, could be retrieved using short-term methods.     

A blood group-related polymorphism of CD44 abolishes a hyaluronan-binding consensus sequence without preventing hyaluronan binding

CD44 is a widely expressed integral membrane protein that acts as a receptor for hyaluronan (HA) and is proposed to be important to cell-extracellular matrix interaction. The Indian (In) blood group antigens reside on CD44, and most individuals express the Inb antigen. Homozygosity for the Ina allele occurs as a rare event and is associated with production of alloantibody to the common Inb antigen after transfusion or pregnancy. The present study demonstrates that a single point mutation (G252 --> C) causes an Arg46 --> Pro substitution, which is responsible for the Inb/Ina polymorphism. Additional mutations were found in In(a+b-) cDNA but were not necessary to the antigenic phenotype as determined in site-directed mutagenesis studies. In studies using CD44 chimeric constructs, Arg46 has previously been shown to be crucial for maintenance of HA-binding ability to a CD44 peptide. However, the present study demonstrates that the Arg46 --> Pro substitution does not reduce HA binding to the intact CD44 protein, which contains two proposed extracellular HA-binding motifs. Down-regulation of HA binding to In(a+b-) CD44 by anti-CD44 monoclonal antibody (mAb) ligands, however, was weakened, although all mAbs tested bound In(a+b-) and In(a-b+) CD44 equally well. Competitive inhibition studies using human anti-Inb also showed that some mAbs that inhibit HA binding to CD44 may do so by interacting with a domain separate from, but affecting the structure of, the Inb epitope.     

Alternative Reagents for Methotrexate as Immobilizing Anchor Moieties in the Optimization of MASPIT: Synthesis and Biological Evaluation

We report the evaluation of two alternative chemical dimerizer approaches aimed at increasing the sensitivity of MASPIT, a three‐hybrid system that enables small‐molecule target protein profiling in intact human cells. To circumvent the potential limitations related to the binding of methotrexate (MTX) to endogenous human dihydrofolate reductase (DHFR), we explored trimethoprim (TMP) as an alternative prokaryote‐specific DHFR ligand. MASPIT evaluation of TMP fusion compounds with tamoxifen, reversine, and simvastatin as model baits, resulted in dose–response curves shifted towards lower EC₅₀ values than those of their MTX congeners. Furthermore, a scalable azido‐TMP reagent was synthesized that displayed a similar improvement in sensitivity, possibly owing to increased membrane permeability relative to the MTX anchor. Applying the SNAP‐tag approach to introduce a covalent bond into the system, on the other hand, produced an inferior readout than in the MTX‐ or TMP‐tag based assay.     

Logic, beliefs, and instruction: A test of the default interventionist account of belief bias.

According to dual-process accounts of thinking, belief-based responses on reasoning tasks are generated as default but can be intervened upon in favor of logical responding, given sufficient time, effort, or cognitive resource. In this article, we present the results of 5 experiments in which participants were instructed to evaluate the conclusions of logical arguments on the basis of either their logical validity or their believability. Contrary to the predictions arising from these accounts, the logical status of the presented conclusion had a greater impact on judgments concerning its believability than did the believability of the conclusion on judgments about whether it followed logically. This finding was observed when instructional set was presented as a between-participants factor (Experiment 1), when instruction was indicated prior to problem presentation by a cue (Experiment 2), and when the cue appeared simultaneously with conclusion presentation (Experiments 3 and 4). The finding also extended to a range of simple and more complex argument forms (Experiment 5). In these latter experiments, belief-based judgments took significantly longer than those made under logical instructions. We discuss the implications of these findings for default interventionist accounts of belief bias. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Managing the Co‐operation–Competition Dilemma in R&D Alliances: A Multiple Case Study in the Advanced Materials Industry

Generating value in R&D alliances requires intensive and fine‐grained interaction between collaborating partners. At the same time, more intensive co‐operation increases the risk of competitive abuse of the R&D alliance by one or more partners. In this study, we explore how managers address the fundamental tension between the need for co‐operation and the risk of competition, using an in‐depth case study of five R&D alliances in the advanced materials industry. Based on our data, we identify two relational strategies to enhance co‐operation between engineers of different partners (i.e., adopting boundary‐spanning activities and installing similar technical equipment) and three structural strategies to mitigate the risk of such intensified co‐operation (i.e., definition of partner‐specific task domains, definition of partner‐specific knowledge domains and definition of partner‐specific commercial domains). In addition, we find that partners tend to use particular combinations of such relational and structural strategies at different stages of the alliance life‐cycle to address the co‐operation–competition dilemma.