Concept: Fourier transform spectroscopy
Collisions of excitation pulses in dissipative systems lead usually to their annihilation. In this paper, we report electrochemical experiments exhibiting more complex pulse interaction with collision survival and pulse splitting, phenomena that have rarely been observed experimentally and are only poorly understood theoretically. Using spatially resolved in-situ Fourier transform infrared spectroscopy (FTIR) in the attenuated total reflection configuration, we monitored reaction pulses during the electrochemical oxidation of CO on Pt thin film electrodes in a flow cell. The system forms quasi-1d pulses that align parallel to the flow and propagate perpendicular to it. The pulses split once in a while, generating a second solitary wave in the backward moving direction. Upon collision, the waves penetrate each other in a soliton-like manner. These unusual pulse dynamics could be reproduced with a 3-component reaction-diffusion-migration model with two inhibitor species, one of them exhibiting a long-range spatial coupling. The simulations shed light on existence criteria of such dissipative solitons.
A simple method for incorporating amine groups in hydrogenated castor oil (HCO) to produce wax for beeswax or carnauba wax substitution in packaging and coating was developed. From the conversion rate of the products, HCO was reacted with ethanolamine at 150°C for 5 h, and the molar ratio of HCO and ethanolamine was 1:4. The hardness of the final product was seven times higher than that of beeswax, the cohesiveness of the final product was 1.3 times higher than that of beeswax and approximately one half of that of carnauba wax, and the melting point of the final product is 98°C. The Fourier transform Infrared spectroscopy showed that the amide groups were incorporated to form the amide products. In coating application, the results showed that the force of the final product coating cardboard was higher than that of beeswax and paraffin wax and less than that of carnauba wax. After 24 h soaking, the compression forces were decreased. HCO fatty acid wax can be an alternative wax for carnauba wax and beeswax in coating applications.
Time-resolved Fourier transform infrared (FTIR) spectroscopy is a powerful tool to elucidate label-free the reaction mechanisms of proteins. After assignment of the absorption bands to individual groups of the protein, the order of events during the reaction mechanism can be monitored and rate constants can be obtained. Additionally, structural information is encoded into infrared spectra and can be decoded by combining the experimental data with biomolecular simulations. We have determined recently the infrared vibrations of GTP and guanosine diphosphate (GDP) bound to Gαi1, a ubiquitous GTPase. These vibrations are highly sensitive for the environment of the phosphate groups and thereby for the binding mode the GTPase adopts to enable fast hydrolysis of GTP. In this study we calculated these infrared vibrations from biomolecular simulations to transfer the spectral information into a computational model that provides structural information far beyond crystal structure resolution. Conformational ensembles were generated using 15 snapshots of several 100 ns molecular-mechanics/molecular-dynamics (MM-MD) simulations, followed by quantum-mechanics/molecular-mechanics (QM/MM) minimization and normal mode analysis. In comparison with other approaches, no time-consuming QM/MM-MD simulation was necessary. We carefully benchmarked the simulation systems by deletion of single hydrogen bonds between the GTPase and GTP through several Gαi1 point mutants. The missing hydrogen bonds lead to blue-shifts of the corresponding absorption bands. These band shifts for α-GTP (Gαi1-T48A), γ-GTP (Gαi1-R178S), and for both β-GTP/γ-GTP (Gαi1-K46A, Gαi1-D200E) were found in agreement in the experimental and the theoretical spectra. We applied our approach to open questions regarding Gαi1: we show that the GDP state of Gαi1 carries a Mg(2+), which is not found in x-ray structures. Further, the catalytic role of K46, a central residue of the P-loop, and the protonation state of the GTP are elucidated.
This study presents, attenuated total reflection Fourier transforms infrared spectroscopy of dried serum samples in an effort to assess biochemical changes induced by non-Hodgkin’s lymphoma and subcutaneous melanoma. An EL4 mouse model of non-Hodgkin lymphoma and a B16 mouse model of subcutaneous melanoma are used to extract a snapshot of tumor-associated alteration in the serum. The study of both cancer-bearing mouse models in wild types and their corresponding control types, emphasizes the diagnostic potential of this approach as a screening technique for non-Hodgkin lymphoma and melanoma skin cancer. Infrared absorbance values of the different spectral bands, hierarchical clustering and integral values of the component bands by curve fitting, show statistically significant differences (student’s t-test, two-tailed unequal variance p-value < 0.05) between spectra representing healthy and tumorous mouse. This technique may thus be useful for having individualized route maps for rapid evaluation of lymphoma and melanoma status and associated therapeutic modalities.
We investigated microplastics in the digestive tracts of 64 Japanese anchovy (Engraulis japonicus) sampled in Tokyo Bay. Plastic was detected in 49 out of 64 fish (77%), with 2.3 pieces on average and up to 15 pieces per individual. All of the plastics were identified by Fourier transform infrared spectroscopy. Most were polyethylene (52.0%) or polypropylene (43.3%). Most of the plastics were fragments (86.0%), but 7.3% were beads, some of which were microbeads, similar to those found in facial cleansers. Eighty percent of the plastics ranged in size from 150 μm to 1000 μm, smaller than the reported size range of floating microplastics on the sea surface, possibly because the subsurface foraging behavior of the anchovy reflected the different size distribution of plastics between surface waters and subsurface waters. Engraulis spp. are important food for many humans and other organisms around the world. Our observations further confirm that microplastics have infiltrated the marine ecosystem, and that humans may be exposed to them. Because microplastics retain hazardous chemicals, increase in fish chemical exposure by the ingested plastics is of concern. Such exposure should be studied and compared with that in the natural diet.
Polystyrene (PS) is generally considered to be durable and resistant to biodegradation. Mealworms (the larvae of Tenebrio molitor Linnaeus) from different sources chew and eat Styrofoam, a common PS product. The Styrofoam was efficiently degraded in the larval gut within a retention time of less than 24 h. Fed with Styrofoam as the sole diet, the larvae lived as well as those fed with a normal diet (bran) over a period of one month. The analysis of fecula egested from Styrofoam-feeding larvae, using gel permeation chromatography (GPC), solid state 13C cross polarization/magic angle spinning nuclear magnetic resonance (CP/MAS NMR) spectroscopy and thermogravimetric Fourier transform infrared (TG-FTIR) spectroscopy, substantiated that cleavage/depolymerization of long-chain PS molecules and the formation of depolymerized metabolites occurred in the larval gut. Within a 16-day test period, 47.7% of the ingested Styrofoam carbon was converted into CO2, and the residue (ca. 49.2%) was egested as fecula with a limited fraction incorporated into biomass (ca. 0.5%). Tests with α13C- or β13C-labeled PS confirmed that the 13C-labeled PS was mineralized to 13CO2 and incorporated into lipids. The discovery of the rapid biodegradation of PS in the larval gut reveals a new fate for plastic waste in the environment.
The present study provides a rapid way to obtain VO2 (B) under economical and environmentally friendly conditions. VO2 (B) is one of the well-known polymorphs of vanadium dioxide and is a promising cathode material for aqueous lithium ion batteries. VO2 (B) was successfully synthesized by rapid single-step hydrothermal process using V2O5 and citric acid as precursors. The present study shows that phase-pure VO2 (B) polytype can be easily obtained at 180 °C for 2 h and 220 °C for 1 h, that is, the lowest combination of temperature and duration reported so far. The obtained VO2 (B) is characterized by X-ray powder diffraction, high-resolution scanning electron microscopy, and Fourier transform infrared spectroscopy. In addition, we present an indirect way to obtain VO2 (M1) by annealing VO2 (B) under vacuum for 1 h.
Improved methods are required for the recycling of waste printed circuit boards (WPCBs). In this study, WPCBs (1-1.5 cm2 in size) were separated into their components using dimethyl sulfoxide (DMSO) at 60°C for 45 min and a metallographic microscope used to verify their delamination. An increased incubation time of 210 min yielded a complete separation of WPCBs into their components, and copper foils and glass fibers were obtained. The separation time decreased with increasing temperature. When the WPCB size was increased to 2-3 cm2, the temperature required for complete separation increased to 90°C. When the temperature was increased to 135°C, liquid photo solder resists could be removed from the copper foil surfaces. The DMSO was regenerated by rotary decompression evaporation, and residues were obtained. Fourier transform infrared spectroscopy (FT-IR), thermal analysis, nuclear magnetic resonance, scanning electron microscopy and energy-dispersive x-ray spectroscopy were used to verify that these residues were brominated epoxy resins. From FT-IR analysis after the dissolution of brominated epoxy resins in DMSO it was deduced that hydrogen bonding may play an important role in the dissolution mechanism. This novel technology offers a method for separating valuable materials and preventing environmental pollution from WPCBs.
The purpose of this study is to develop a green strategy to synthesize the cellulose-based nanocomposites and open a new avenue to the high value-added applications of biomass. Herein, we reported a microwave-assisted ionic liquid route to the preparation of cellulose/CuO nanocomposites, which combined three major green chemistry principles: using environmentally friendly method, greener solvents, and sustainable resources. The influences of the reaction parameters including the heating time and the ratio of cellulose solution to ionic liquid on the products were discussed by X-ray powder diffraction, Fourier transform infrared spectrometry, and scanning electron microscopy. The crystallinity of CuO increased and the CuO shape changed from nanosheets to bundles and to particles with increasing heating time. The ratio of cellulose solution to ionic liquid also affected the shapes of CuO in nanocomposites. Moreover, CuO crystals were obtained by thermal treatment of the cellulose/CuO nanocomposites at 800 °C for 3 h in air.
The effectiveness of attenuated total reflection Fourier transform infrared spectroscopy for the hematological analysis of thalassemias was evaluated.