SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: The Matrix

28

Currently, much attention is being paid to patterned multilayer systems in which there exists a perpendicular magnetic anisotropy, because of their potential applications in spintronics devices and in a new generation of magnetic storage media. To further improve their performance, different patterning techniques can be used, which render them suitable also for other applications. Here we show that He(+) 10 keV and Ar(+) 100 keV ion bombardment of (Ni(80)Fe(20)-2 nm/Au-2 nm/Co-0.6 nm/Au-2 nm)(10) multilayers through colloidal mask enables magnetic patterning of regularly arranged cylindrical magnetic domains, with perpendicular anisotropy, embedded in a non-ferromagnetic matrix or in a ferromagnetic matrix with magnetization oriented along the normal. These domains form an almost perfect two-dimensional hexagonal lattice with a submicron period and a large correlation length in a continuous and flat multilayer system. The magnetic anisotropy of these artificial domains remains unaffected by the magnetic patterning process, however the magnetization configuration of such a system depends on the magnetic properties of the matrix. The micromagnetic simulations were used to explain some of the features of the investigated patterned structures.

Concepts: Electron, Magnetic field, Magnetism, Ferromagnetism, Artificial intelligence, The Matrix, Storage media, Domain wall

27

We have developed heterogeneous polymer-incarcerated nickel nanoparticles, which catalyzed cross-coupling reactions. The matrix structure of these catalysts incorporates both N-heterocycle carbenes (NHCs) as ligands and nickel nanoparticles, thanks to a new design of cross-linking agents in polymer supports. These embedded NHCs were detected by Field Gradient Swollen-Resin Magic Angle Spinning (FGSR-MAS) NMR analysis. They were successfully applied to Corriu-Kumada-Tamao reactions with a broad substrate scope and could be recovered and reused several times without loss of activity.

Concepts: Enzyme, Chemical reaction, Hydrogen, Nuclear magnetic resonance, Chemical equilibrium, The Matrix, Magic angle spinning, Magic angle

27

This paper describes the matrix effect during the analysis of ten antibiotic compounds in water by SPE followed by HPLC-ESI-MS/MS. The target analytes were tetracycline, oxytetracycline (tetracyclines), sulfathiazole, sulfamethazine, sulfadiazine (sulfonamides), erythromycin-H(2) O, roxithromycine, spiramycin (macrolides), ofloxacin, and norfloxacin (quinolones). The matrix effect was examined for internal standards and the target analytes in five different water matrixes, with signal suppression being increased in the order: ultrapure water, tap water, river water, sewage effluent, and sewage influent. A combined application of the internal standards and matrix-matched extract calibration was shown to be successful in compensating the matrix effect for the analytes. The procedural recovery of the target compounds in sewage effluents and influents was higher than in river water samples, which was further enhanced by sample acidification to pH 2. The validity of the internal standard based matrix-matched calibration approach was verified by the standard addition method.

Concepts: Mass spectrometry, Analytical chemistry, Sewage treatment, The Matrix, Liquid chromatography-mass spectrometry, Quinolone, Standard addition, Tetracycline antibiotics

26

Intravenous lipid emulsion (ILE) has been used widely for the treatment of poisoning due to local anesthetic agent and is increasingly reported as a therapy for other forms of poisoning. This article will review the proposed mechanisms of action for ILE in poisoning and the evidence from animal studies and human experience supporting the use of ILE for poisoning due to nonlocal anesthetic agents.

Concepts: Anesthesia, Local anesthesia, The Matrix, Local anesthetic, Agent, Lipid rescue

5

Viral metagenomics (viromics) is increasingly used to obtain uncultivated viral genomes, evaluate community diversity, and assess ecological hypotheses. While viromic experimental methods are relatively mature and widely accepted by the research community, robust bioinformatics standards remain to be established. Here we used in silico mock viral communities to evaluate the viromic sequence-to-ecological-inference pipeline, including (i) read pre-processing and metagenome assembly, (ii) thresholds applied to estimate viral relative abundances based on read mapping to assembled contigs, and (iii) normalization methods applied to the matrix of viral relative abundances for alpha and beta diversity estimates.

Concepts: Scientific method, Bioinformatics, Genomics, Research, Relative, The Matrix, Community, Compiler

4

This in vitro study investigated the metabolism of human osteoarthritic (OA) chondrocytes encapsulated in a spherical matrix enriched of chitosan. Human OA chondrocytes were encapsulated and cultured for 28 days either in chitosan-alginate beads or in alginate beads. The beads were formed by slowly passing dropwise either the chitosan 0.6%-alginate 1.2% or the alginate 1.2% solution through a syringe into a 102 mM CaCl2 solution. Beads were analyzed histologically after 28 days. Interleukin (IL)-6 and -8, prostaglandin (PG) E2, matrix metalloproteinases (MMPs), hyaluronan and aggrecan were quantified directly in the culture supernatant by specific ELISA and nitric oxide (NO) by using a colorimetric method based on the Griess reaction. Hematoxylin and eosin staining showed that chitosan was homogeneously distributed through the matrix and was in direct contact with chondrocytes. The production of IL-6, IL-8 and MMP-3 by chondrocytes significantly decreased in chitosan-alginate beads compared to alginate beads. PGE2 and NO decreased also significantly but only during the first three days of culture. Hyaluronan and aggrecan production tended to increase in chitosan-alginate beads after 28 days of culture. Chitosan-alginate beads reduced the production of inflammatory and catabolic mediators by OA chondrocytes and tended to stimulate the synthesis of cartilage matrix components. These particular effects indicate that chitosan-alginate beads are an interesting scaffold for chondrocytes encapsulation before transplantation to repair cartilage defects.

Concepts: Inflammation, Cartilage, Nitrogen, In vitro, Matrix metalloproteinase, The Matrix, Eosin, The Culture

3

With the ability to observe the activity from large numbers of neurons simultaneously using modern recording technologies, the chance to identify sub-networks involved in coordinated processing increases. Sequences of synchronous spike events (SSEs) constitute one type of such coordinated spiking that propagates activity in a temporally precise manner. The synfire chain was proposed as one potential model for such network processing. Previous work introduced a method for visualization of SSEs in massively parallel spike trains, based on an intersection matrix that contains in each entry the degree of overlap of active neurons in two corresponding time bins. Repeated SSEs are reflected in the matrix as diagonal structures of high overlap values. The method as such, however, leaves the task of identifying these diagonal structures to visual inspection rather than to a quantitative analysis. Here we present ASSET (Analysis of Sequences of Synchronous EvenTs), an improved, fully automated method which determines diagonal structures in the intersection matrix by a robust mathematical procedure. The method consists of a sequence of steps that i) assess which entries in the matrix potentially belong to a diagonal structure, ii) cluster these entries into individual diagonal structures and iii) determine the neurons composing the associated SSEs. We employ parallel point processes generated by stochastic simulations as test data to demonstrate the performance of the method under a wide range of realistic scenarios, including different types of non-stationarity of the spiking activity and different correlation structures. Finally, the ability of the method to discover SSEs is demonstrated on complex data from large network simulations with embedded synfire chains. Thus, ASSET represents an effective and efficient tool to analyze massively parallel spike data for temporal sequences of synchronous activity.

Concepts: Scientific method, Method acting, Mathematical analysis, English-language films, Sequence, Parallel computing, Demonstration, The Matrix

3

One of the large remaining challenges in the field of zebrafish neuroscience is the establishment of techniques and preparations that permit the recording and perturbation of neural activity in animals that can interact meaningfully with the environment. Since it is very difficult to do this in freely behaving zebrafish, I describe here two alternative approaches that meet this goal via tethered preparations. The first uses head-fixation in agarose in combination with online imaging and analysis of tail motion. In the second method, paralyzed fish are suspended with suction pipettes in mid-water and nerve root recordings serve as indicators for intended locomotion. In both cases, fish can be immersed into a virtual environment and allowed to interact with this virtual world via real or fictive tail motions. The specific examples given in this review focus primarily on the role of visual feedback~- but the general principles certainly extend to other modalities, including proprioception, hearing, balance, and somatosensation.

Concepts: Nervous system, Fish, Motor control, Sensory system, Sense, The Matrix, Simulated reality, Virtual reality

2

The neuromuscular blocking agent cisatracurium may improve mortality for patients with moderate-severe ARDS. Other neuromuscular blocking agents, such as vecuronium, are commonly used and have different mechanisms of action, side effects, cost, and availability in the setting of drug shortages.

Concepts: Observational study, The Matrix, Agent, Muscle relaxants, Cisatracurium, Neuromuscular-blocking drug

2

Microbial biofilm systems are defined as interface-associated microorganisms embedded into a self-produced matrix. The extracellular matrix represents a continuous challenge in terms of characterization and analysis. The tools applied in more detailed studies comprise extraction/chemical analysis, molecular characterization, and visualisation using various techniques. Imaging by laser microscopy became a standard tool for biofilm analysis, and, in combination with fluorescently labelled lectins, the glycoconjugates of the matrix can be assessed. By employing this approach a wide range of pure culture biofilms from different habitats were examined using the commercially available lectins. From the results, a binary barcode pattern of lectin binding can be generated. Furthermore, the results can be fine-tuned and transferred into a heat map according to signal intensity. The lectin barcode approach is suggested as a useful tool for investigating the biofilm matrix characteristics and dynamics at various levels, e.g. bacterial cell surfaces, adhesive footprints, individual microcolonies, and the gross biofilm or bio-aggregate. Hence fluorescence lectin bar-coding (FLBC) serves as a basis for a subsequent tailor-made fluorescence lectin-binding analysis (FLBA) of a particular biofilm. So far, the lectin approach represents the only tool for in situ characterization of the glycoconjugate makeup in biofilm systems.  Furthermore, lectin staining lends itself to other fluorescence techniques in order to correlate it with cellular biofilm constituents in general and glycoconjugate producers in particular.

Concepts: Archaea, Bacteria, Microbiology, Pseudomonas aeruginosa, Biofilm, The Matrix, Microorganism, Lectins