Biosynthesis of Quantum Dots (CdTe) and its Effect on Eisenia fetida and Escherichia coli

Biosynthesis belongs to one of the new possibilities of nanoparticles preparation, whereas its main advantage is biocompatibility. In addition, the ability of obtaining the raw material for such synthesis from the soil environment is beneficial and could be useful for remediation. However, the knowledge of mechanisms that are necessary for the biosynthesis or effect on the bio-synthesizing organisms is still insufficient. In this study, we attempted to evaluate the effect of quantum dots (QDs) not only on a model organism of collembolans, but also on another soil organism—earthworm Eisenia fetida—and in also one widespread microorganism such as Escherichia coli. Primarily, we determined 28EC₅₀ as 72.4 μmol L⁻¹ for CdTe QDs in collembolans. Further, we studied the effect of QDs biosynthesis in E. fetida and E. coli. Using determination of QDs, low-molecular thiols and antioxidant activities, we found differences between both organisms and also between ways how they behave in the presence of Cd and/or Cd and Te. The biosynthesis in earthworms can be considered as its own protective mechanism; however, in E. coli, it is probably a by-product of protective mechanisms.

     

Interference of Data Transmission in Access and Backbone Networks by High-Power Sensor System

Currently, individual optical fibers are mostly used for each non-data application, which is very inefficient and uneconomical. Sharing a single fiber for multiple applications is a promising solution. However, in the case of a non-data application, the situation is much more complicated compared to data because of special application´s requirements. In laboratory setup, we performed a measurement with a standard G.652D optical fiber for analyzing possible interaction of stable frequency/accurate time transmission, 1.25/10Gbps data transmission (typical bitrates for access point-to-point networks), and high-power sensor signal for different channel spacing and different pulse duration of sensor signal.     

Meta nitration of thiacalixarenes

Nitration of thiacalix[4]arene, immobilized in the 1,3-alternate conformation, leads regioselectively to meta-substituted products. Depending on the reaction conditions, mono- and dinitro-derivatives can be isolated in acceptable yields. This unique substitution pattern is inaccessible in classical calixarene chemistry, and yields inherently chiral compounds, which makes thiacalixarenes very attractive as building blocks or molecular scaffolds.     

Identification/quantification of multiple pesticide residues in food plants by ultra-high-performance liquid chromatography-time-of-flight mass spectrometry

In this study, the potential of ultra-high-performance liquid chromatography coupled with the time-of-flight mass spectrometry (UHPLC–TOF MS) to enable rapid and comprehensive analysis of 212 pesticide residues in QuEChERS extracts obtained from four plant matrices has been investigated. Method optimization is discussed in detail. In addition to molecular adducts, also fragment ions were provided for all target pesticides, thus obtaining at least three identification points required by European Decision 2002/657/EC was achieved. To get maximum information on analytes present in the extracts, each sample was examined within two injections, the first in a positive and the next one in a negative ionization mode. Under UHPLC conditions, both analyses were completed within 24 min. For more than 96% of pesticides involved in this study, the limit of quantification was ≤10 μg/kg. As a part of the work, strategy enabling screening of non-target pesticides and their metabolites is demonstrated on analysis of real-life samples.     

Real‐Time Nanomicroscopy via Three‐Dimensional Single‐Particle Tracking

We developed a new method for real‐time, three‐dimensional tracking of fluorescent particles. The instrument is based on a laser‐scanning confocal microscope where the focus of the laser beam is scanned or orbited around the particle. Two confocal pinholes are used to simultaneously monitor regions immediately above and below the particle and a feedback loop is used to keep the orbit centered on the particle. For moderate count rates, this system can track particles with 15 nm spatial resolution in the lateral dimensions and 50 nm in the axial dimension at a temporal resolution of 32 ms. To investigate the interaction of the tracked particles with cellular components, we have combined our orbital tracking microscope with a dual‐color, wide‐field setup. Dual‐color fluorescence wide‐field images are recorded simultaneously in the same image plane as the particle being tracked. The functionality of the system was demonstrated by tracking fluorescent‐labeled artificial viruses in tubulin‐eGFP expressing HUH7 cells. The resulting trajectories can be used to investigate the microtubule network with super resolution.     

Preparation of Bragg mirrors on silica optical fibers and inner walls of silica capillaries by employing the sol–gel method,and titanium and silicon alkoxides

Journal of Sol-Gel Science and Technology - The paper presents results on sol–gel preparation and characterization of multilayered coatings, Bragg mirrors, on silica slides, silica fibers,...