Search results for " Modification"

Study of Inductive Coupled Hydrogen and Argon Plasma Interaction with SiO2 Glass

2009

This work is devoted to the diagnostics of interaction between hydrogen and argon with the surface of SiO2 glass walls. For diagnostics of the interaction, special high-frequency electrodeless light sources were prepared, filled with pure argon of 1 Torr or argon-hydrogen of total pressure of 1 Torr (Ar/H2 mixing ratio is 9:1). Besides the mostly used spherical and cylindrical lamps, dumbbell type lamps have also been investigated. The spectroscopic and AFM measurements showed that in comparison with pure argon plasma, the argon-hydrogen plasma causes non-uniform changes of the SiO2 surface. For these modifications active OH are primarily responsible molecules, created in the reactions of h…

Speech Emotion Recognition method using time-stretching in the Preprocessing Phase and Artificial Neural Network Classifiers

2020

Human emotions are playing a significant role in the understanding of human behaviour. There are multiple ways of recognizing human emotions, and one of them is through human speech. This paper aims to present an approach for designing a Speech Emotion Recognition (SER) system for an industrial training station. While assembling a product, the end user emotions can be monitored and used as a parameter for adapting the training station. The proposed method is using a phase vocoder for time-stretching and an Artificial Neural Network (ANN) for classification of five typical different emotions. As input for the ANN classifier, features like Mel Frequency Cepstral Coefficients (MFCCs), short-te…

2011

Abstract. The ability of coated mineral dust particles to act as ice nuclei (IN) was investigated at LACIS (Leipzig Aerosol Cloud Interaction Simulator) during the FROST1- and FROST2-campaigns (Freezing of dust). Sulphuric acid was condensed on the particles which afterwards were optionally humidified, treated with ammonia vapour and/or heat. By means of aerosol mass spectrometry we found evidence that processing of mineral dust particles with sulphuric acid leads to surface modifications of the particles. These surface modifications are most likely responsible for the observed reduction of the IN activation of the particles. The observed particle mass spectra suggest that different treatme…

Cytotoxic activity of several ent-kaurane derivatives of atractyligenin. Synthesis of unreported diterpenic skeleton by chemical rearrangement

2022

Atractyloside, carboxyatractyloside, their aglycon atractyligenin, and several synthetic derivatives were tested and found to be active against a panel of human tumor cell lines. Atractyligenin was subjected to oxidation, bromination, and elimination reactions, obtaining several compounds. A singular skeleton was synthesized by chemical rearrangement starting from 3 beta-bromo-2,15-diketoatractyligenin methyl ester. The synthesized compounds resulted active against all cell lines tested. In particular, 15-ketoatractyligenin methyl ester and 3 beta bromo-2,15-diketoatractyligenin methyl ester resulted the most active with IC50 values of 0.427 and 0.723 mu M against A375 melanoma cell line. E…

Functionalization using biocompatible carboxylated cyclodextrins of iron-based nanoMIL-100

2021

9 pags., 7 figs., 1 tab.

Generic Method for Modular Surface Modification of Cellulosic Materials in Aqueous Medium by Sequential Click-Reaction and Adsorption

2012

A generic approach for heterogeneous surface modification of cellulosic materials in aqueous medium, applicable for a wide range of functionalizations, is presented. In the first step, carboxymethyl cellulose (CMC) modified with azide or alkyne functionality, was adsorbed on a cellulosic substrate, thus, providing reactive sites for azide–alkyne cycloaddition click reactions. In the second step, functional units with complementary click units were reacted on the cellulose surface, coated by the click-modified CMC. Selected model functionalizations on diverse cellulosic substrates are shown to demonstrate the generality of the approach. The concept by sequentially combining the robust physic…

The selective synthesis of metallanucleosides and metallanucleotides: a new tool for the functionalization of nucleic acids.

2012

Nucleobases team up: the efficient and selective preparation of purine-derived metallanucleosides, metallanucleotides, and metalladinucleotides having M-C bonds (M=Ir(III), Rh(III)) is reported for the first time. The results presented may be applied to the synthesis of functionalized nucleic acids, or DNA/RNA-modified segments.

Kinetics of the Strain-Promoted Oxidation-Controlled Cycloalkyne-1,2-quinone Cycloaddition: Experimental and Theoretical Studies

2018

Stimulated by its success in both bioconjugation and surface modification, we studied the strain-promoted oxidation-controlled cycloalkyne–1,2-quinone cycloaddition (SPOCQ) in three ways. First, the second-order rate constants and activation parameters (ΔH⧧) were determined of various cyclooctynes reacting with 4-tert-butyl-1,2-quinone in a SPOCQ reaction, yielding values for ΔH⧧ of 4.5, 7.3, and 12.1 kcal/mol, for bicyclo[6.1.0]non-4-yne (BCN), cyclooctyne (OCT), and dibenzoazacyclooctyne (DIBAC), respectively. Second, their reaction paths were investigated in detail by a range of quantum mechanical calculations. Single-configuration theoretical methods, like various DFT and a range of MP2…

2015

The combination of Reverse Transcription (RT) and high-throughput sequencing has emerged as a powerful combination to detect modified nucleotides in RNA via analysis of either abortive RT-products or of the incorporation of mismatched dNTPs into cDNA. Here we simultaneously analyze both parameters in detail with respect to the occurrence of N-1-methyladenosine (m(1)A) in the template RNA. This naturally occurring modification is associated with structural effects, but it is also known as a mediator of antibiotic resistance in ribosomal RNA. In structural probing experiments with dimethylsulfate, m(1)A is routinely detected by RT-arrest. A specifically developed RNA-Seq protocol was tailored…

Polylactic is a Sustainable, Low Absorption, Low Autofluorescence Alternative to Other Plastics for Microfluidic and Organ-on-Chip Applications

2020

Organ-on-chip (OOC) devices are miniaturized devices replacing animal models in drug discovery and toxicology studies. The majority of OOC devices are made from polydimethylsiloxane (PDMS), an elastomer widely used in microfluidic prototyping, but posing a number of challenges to experimentalists, including leaching of uncured oligomers and uncontrolled absorption of small compounds. Here we assess the suitability of polylactic acid (PLA) as a replacement material to PDMS for microfluidic cell culture and OOC applications. We changed the wettability of PLA substrates and demonstrated the functionalization method to be stable over a time period of at least 9 months. We successfully cultured …