Pyrolysis-gas chromatography (Py-GC) has become well established as a simple, quick and reliable analytical technique for a range of applications including the analysis of polymeric materials. Recent developments in Py-GC technology and instrumentation include laser pyrolysis and non-discriminating pyrolysis. Progress has also been made in the detection of low-level polymer additives with the use of novel Py-GC devices. Furthermore, it has been predicted that future advances in separation technology such as the use of comprehensive two-dimensional gas chromatography will further enhance the analytical scope of Py-GC. 相似文献
Herein we report a novel strategy for the in situ synthesis of the silver colloids for LoC-SERS applications. Silver nanoparticles are obtained in a segmented flow based glass microfluidic chip by the reduction of silver ions with hydrazine in ammonium hydroxide solution. Citrate ions are used as protecting agents. The synthesized nanoparticles are characterized by UV-VIS spectroscopy, SEM and TEM imaging. The SERS performance of the in situ synthesized nanoparticles is tested by using adenine as a test analyte right after the colloid synthesis. Reproducibility is tested by repeating the measurements three times at independent days applying the same measurement conditions. In comparison with nanoparticles synthesized in a conventional strategy i.e. in a large batch, chip synthesized nanoparticles show a better day-to-day and long-term reproducibility, lower detection limits and broader working ranges. The great advantage offered by the in situ synthesized colloids combined with the already proven potential of LoC-SERS for bioanalytics, raises the possibility of the employment of LoC-SERS as a fast and sensitive analytic tool in a plethora of applications. 相似文献
A timesaving and convenient method for bacterial detection based on one‐step, one‐tube deoxyribonucleic acid (DNA) hybridization on hydrogel array while target gene amplification is described. The hydrogel array is generated by a fast one‐pot synthesis, where N,N′‐dimethylacrylamide/polyethyleneglycol(PEG1900)‐bisacrylamide mixture polymerizes via radical photoinitiation by visible light within 20 min concomitant with in situ capture probe immobilization. These DNA‐functionalized hydrogel droplets arrayed on a planar glass surface are placed in the polymerase chain reaction (PCR) mixture during the thermal amplification cycles. The bacterial cells can be implemented in a direct PCR reaction, omitting the need for prior template DNA extraction. The resulting fluorescence signal is immediately detectable after the end of the PCR (1 h) following one short washing step by microscopy. Therefore a valid signal can be reached within 1.5 h including 10 min for pipetting and placement of the tubes and chips. The performance of this novel hydrogel DNA array was successfully proven with varying cell numbers down to a limit of 101Escherichia coli cells.
Electrospinning is a versatile technique providing highly tunable nanofibrous nonwovens. Many biomedical applications have been developed for nanofibers, among which the production of antimicrobial mats stands out. The production of scaffolds for tissue engineering, fibers for controlled drug release, or active wound dressings are active fields of research exploiting the possibilities offered by electrospun materials. The fabrication of materials for active food packaging or membranes for environmental applications is also reviewed. We attempted to give an overview of the most recent literature related with applications in which nanofibers get in contact with living cells and develop a nano-bio interface. 相似文献
Binary brushes constituted from two incompatible polymers can be used in the form of ultrathin polymeric layers as a versatile tool for surface engineering to tune physicochemical surface characteristics such as wettability, surface charge, chemical composition, and morphology and furthermore to create responsive surface properties. Mixed brushes of oppositely charged weak polyelectrolytes represent a special case of responding surfaces that are sensitive to changes in the pH value of the aqueous environment and therefore represent interesting tools for biosurface engineering. The polyelectrolyte brushes used for this study were composed of two oppositely charged polyelelctrolytes poly(2-vinylpyridine) (P2VP) and poly(acrylic acid) (PAA). The in-situ properties and surface characteristics such as as surface charge, surface tension, and extent of swelling of these brush layers are functions of the pH value of the surrounding aqueous solution. To test the behavior of the mixed polylelctrolyte brushes in contact with biosystems, protein adsorption experiments with globular model proteins were performed at different pH values and salt concentrations (confinement of counterions) of the buffer solutions. The influence of the pH value, buffer salt concentration, and isoelectric points (IEP) of the brush and protein on the adsorbed amount and the interfacial tension during protein adsorption as well as the protein adsorption mechanism postulated in reference to recently developed theories of protein adsorption on polyelectrolyte brushes is discussed. In the salted regime, protein adsorption was found to be similar to the often-described adsorption at hydrophobic surfaces. However, in the osmotic regime the balance of electrostatic repulsion and a strong entropic driving force, "counterion release", was found to be the main influence on protein adsorption. 相似文献
Hyperbranched polyesters (HBP) with different end groups were prepared as thin films. They were characterized with regard to their chemical composition, thickness, optical constants and morphology using infrared spectroscopy, spectroscopic ellipsometry, and atomic force microscopy. The surface properties of the films were determined by zeta‐potential and contact angles measurements. The differences in the molecular structure and surface energetic and acid‐base properties between HBP materials with carboxylic, hydroxy and acetoxy end groups result in differences in their swelling behavior in atmospheric humidity. The swelling behavior at different atmospheric humidity was observed in situ using spectroscopic ellipsometry and reflectometric interference spectroscopy. From the results it can be concluded that HBP films can be used potentially as sensoric materials. 相似文献
The crystal structure of the complexes [Cu(sac)2(bzim)2(H2O)] ( 1 ) and [Cu(sac)2(bzim)(H2O)(EtOH)] · 2 EtOH ( 2 ) (sac = saccharinate anion; bzim = benzimidazole; EtOH = ethanol) was determined by single crystal X‐ray diffractometry. Complex 1 crystallizes in the monoclinic C2/c space group with Z = 8 whereas complex 2 belongs to the triclinic P1 space group with Z = 2. Room temperature magnetic susceptibilities as well as electronic and IR spectra of both complexes were discussed. Their thermal behaviour was investigated by means of TG and DTA methods. 相似文献
Research on the functioning of human cognition has been a crucial problem studied for years. Electroencephalography (EEG) classification methods may serve as a precious tool for understanding the temporal dynamics of human brain activity, and the purpose of such an approach is to increase the statistical power of the differences between conditions that are too weak to be detected using standard EEG methods. Following that line of research, in this paper, we focus on recognizing gender differences in the functioning of the human brain in the attention task. For that purpose, we gathered, analyzed, and finally classified event-related potentials (ERPs). We propose a hierarchical approach, in which the electrophysiological signal preprocessing is combined with the classification method, enriched with a segmentation step, which creates a full line of electrophysiological signal classification during an attention task. This approach allowed us to detect differences between men and women in the P3 waveform, an ERP component related to attention, which were not observed using standard ERP analysis. The results provide evidence for the high effectiveness of the proposed method, which outperformed a traditional statistical analysis approach. This is a step towards understanding neuronal differences between men’s and women’s brains during cognition, aiming to reduce the misdiagnosis and adverse side effects in underrepresented women groups in health and biomedical research. 相似文献