Fourier Transform Infrared Spectroscopy With Attenuated Total Reflectance Research Articles

FTIR-ATR study for adsorption of trypsin in aqueous environment on bare and TiO2 coated ZnSe surfaces

Undesired adsorption of proteins brings big troubles to marine structures. The settled proteins change the physical and chemical properties of the surfaces, which allow marine fouling organisms to settle down on the structures. Therefore, to understand the adsorption mechanism of proteins is very helpful to find an environment-friendly solution against biofouling. Many approaches have been developed to study protein adsorption, but most of them are insufficient to give the chemical interaction information between proteins and surfaces. Fourier transform infrared spectroscopy with attenuated total reflection (FTIR-ATR) is an efficient, fast and non-destructive method for in situ surface measurement, which greatly minimizes the interference of water to infrared spectra, because of the very small depth of penetration of the evanescent wave. In this paper, an in situ FTIR-ATR technology was used to investigate the adsorption process of trypsin on a bare ZnSe surface and on a TiO2 coated ZnSe surface, and the effect of calcium cation strength and ultraviolet light irradiation on the secondary structure of trypsin were also evaluated. FTIR spectra of trypsin showed that Amide I band red shift and Amide II band blue shift in aqueous environment on both surfaces compared with the dry trypsin powder, and the addition of calcium cations further changed the Amide bands position, which indicated that the change of the secondary structure could be interfered by the environment. The hydrogen bond formation between water and trypsin, the interaction between surface and trypsin, the interaction between hydrated calcium cations and trypsin, are major factors to change the secondary structure of trypsin, and UV light irradiation also showed its influence for the secondary structure.

The effect of extrusion puffing on the physicochemical properties of brown rice used for saccharification and Chinese rice wine fermentation

Chinese rice wine (CRW), with its high nutritional value and unique flavor, has been popular in China for thousands of years. The traditional steps of immersion and steam cooking during the brewing of rice wine have several drawbacks, including the long production time, large energy consumption, generation of wastewater and the large production area it occupies. Extrusion puffing has the potential to overcome these drawbacks. In this study, the physicochemical properties of extruded-puffed brown rice obtained under different conditions were analyzed. The puffed extrudates exhibited low bulk density, high water solubility index and higher surface area than the steam-cooked brown rice. Extrusion puffing operates at high temperatures, high pressure and provides mechanical shearing forces, resulting in the puffed extrudates having a higher degree of gelatinization, as determined by X-ray diffractometer (XRD), Fourier transform infrared spectroscopy with attenuated total reflection (FTIR-ATR) and differential scanning calorimetry (DSC), revealed the disruption of the native crystalline structure. The effect of extrusion on enzymatic hydrolysis was evaluated using amylase digestion. The results indicated that puffed extrudates significantly improved the enzymatic hydrolysis rate and yield. Moreover, the catalytic efficiency was evaluated by kinetic constants, with extrusion puffing treatment demonstrating an efficiency18-fold higher than steam-cooked brown rice. Finally, extruded-puffed blown rice was used for Chinese rice wine fermentation. The extruded-puffed blown rice improved alcohol yield during the fermentation process, which increased the wine yield by 12.4% compared to traditional cooking methods.

Metamaterial-enhanced infrared attenuated total reflection spectroscopy.

The use of Fourier transform infrared spectroscopy with attenuated total reflection (FTIR-ATR) allows solid or liquid samples to be characterised directly without specific sample preparation. In such a system, the evanescent waves generated through total internal reflection within a crystal interact with the sample under test. In this work we explore the use of a mid-infrared metasurface to enhance the interaction between molecular vibrations and the evanescent waves. A complementary ring-resonator structure was patterned onto both silicon and SiO2/Si substrates, and the spectral properties of both devices were characterised using a FTIR-ATR system. Minima in reflectance were observed corresponding to the resonance of the metasurface on the silicon substrate, and to the hybrid resonance of phonon modes and metasurface resonances on the SiO2/Si substrate, in good agreement with simulations. Preliminary experiments were undertaken using mixtures containing trace amounts of butyl acetate diluted with oleic acid. Without the use of a metasurface, the minimum concentration of butyl acetate that could be clearly detected was 10%, whereas the use of the metasurface on the SiO2/Si substrate allowed the detection of 1% butyl acetate. This demonstrates the potential of using metasurfaces to enhance trace chemical detection in FTIR-ATR systems.

Solvent Vapour Use – The Unintended Consequences in Textile Conservation

ABSTRACTThe impact of solvent vapour from two solvents, acetone and industrial denatured alcohol (IDA), commonly used in adhesive reactivation in textile conservation, when applied to artificially soiled silk fabric through either Gore-Tex® or Reemay® membranes for exposure times of either 1 or 3 min, was measured using microscopy and ImageJ to monitor the movement of the solid particulates of the soiling, and Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) to monitor the movement of the oily components. Analysis using these techniques successfully showed the movement of large particulates through the textile and a decrease in the presence of oil. Analysis with FTIR-ATR showed that the application of solvent vapour by a poultice method produces more than just a surface change and the vapour can penetrate far enough into the fibres to cause a change in the level of oil through the entire textile. The results showed that the solvents and barrier membranes have characteristic differences which impact on the changes on the soiling. The application of acetone produced a greater change in the movement of oil on the front and back of the samples than the application of IDA, while a comparison between the barrier membranes showed a greater change occurring in the level of oil with the use of Gore-Tex® rather than Reemay®. The time of exposure to solvent vapour made little difference to the changes to the textile soiling. Quantitatively significant results were gathered from analysis of the changes in the oil measured with FTIR-ATR, and qualitative changes in the large particulate soiling, demonstrating the potential usefulness of ImageJ open access software in future historic textile soiling monitoring studies.

Assessing the Aflatoxin B₁ Adsorption Capacity between Biosorbents Using an In Vitro Multicompartmental Model Simulating the Dynamic Conditions in the Gastrointestinal Tract of Poultry.

Experiments were carried out to evaluate the effectiveness of three different biosorbents (banana peel, Pyracantha leaves, and Aloe powder) in removing aflatoxin B1 (AFB1). A noncommercial mycotoxin binder (zeolite) was used as a reference material. A laboratory model that simulated the in vivo conditions of the poultry gastrointestinal tract was utilized to prove the removal efficiency of the biosorbents when added to AFB1-contaminated diet (100 µg/kg). The concentration of AFB1 was determined using antibody-based immunoaffinity column and spectrofluorometry methodologies. Z potential (ζ), point of zero charge (pHpzc), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy with attenuated total reflection (FTIR-ATR), and UV-Vis diffuse reflectance spectroscopy (DRS) techniques were used to further characterize the biosorbents. The addition of the biosorbents (1.5%, w/w) to the diet significantly reduced the bioavailability of AFB1 in the intestinal section. The highest aflatoxin adsorption values were 69% and 70% using Aloe powder and zeolite, respectively. A moderate biosorption uptake of 46% was achieved using Pyracantha leaves. The biomaterial with the lowest removal capacity was banana peel (28%). In conclusion, Aloe powder could be used as an alternative to conventional systems for AFB1 removal.

Study of phase separation in blends of silk fibroin and sodium alginate in solution and in solid state

Silk fibroin (SF) and sodium alginate (SA) are natural polymers with many applications as biomaterials. It is possible to make blends with them in order to improve their properties. Those blends are partially miscible; therefore, understanding the mechanism and phase equilibrium of this system is important to better understand the interaction between these natural polymers. This work analyzed the mechanism of phase separation of SF and SA blends with different composition in solution and in the solid state (as membranes) using small angle light scattering with a He-Ne laser. Polymer interaction and conformation were investigated by Fourier-Transform Infrared Spectroscopy with Attenuated Total Reflectance (FTIR-ATR) and X-Ray Diffraction (XRD), and membrane morphology was analyzed by Scanning Electron Microscopy (SEM). SEM images showed interpenetrated globules in the matrix. Light scattering profile for blends in solution and in the solid state showed a peak of intensity suggesting that phase separation occurs by spinodal decomposition.

Modification of polyethylene tube surface in dielectric barrier discharge

Abstract

Root Differentiation of Agricultural Plant Cultivars and Proveniences Using FTIR Spectroscopy.

The differentiation of roots of agricultural species is desired for a deeper understanding of the belowground root interaction which helps to understand the complex interaction in intercropping and crop-weed systems. The roots can be reliably differentiated via Fourier transform infrared spectroscopy with attenuated total reflection (FTIR-ATR). In two replicated greenhouse experiments, six pea cultivars, five oat cultivars as well as seven maize cultivars and five barnyard grass proveniences (n = 10 plants/cultivar or provenience) were grown under controlled conditions. One root of each plant was harvested and five different root segments of each root were separated, dried and measured with FTIR-ATR spectroscopy. The results showed that, firstly, the root spectra of single pea and single oat cultivars as well as single maize and single barnyard grass cultivars/proveniences separated species-specific in cluster analyses. In the majority of cases the species separation was correct, but in a few cases, the spectra of the root tips had to be omitted to ensure the precise separation between the species. Therefore, species differentiation is possible regardless of the cultivar or provenience. Consequently, all tested cultivars of pea and oat spectra were analyzed together and separated within a cluster analysis according to their affiliated species. The same result was found in a cluster analysis with maize and barnyard grass spectra. Secondly, a cluster analysis with all species (pea, oat, maize and barnyard grass) was performed. The species split up species-specific and formed a dicotyledonous pea cluster and a monocotyledonous cluster subdivided in oat, maize and barnyard grass subclusters. Thirdly, cultivar or provenience differentiations within one species were possible in one of the two replicated experiments. But these separations were less resilient.

Temporal and longitudinal biofilm matrix analysis of a biofilter treating ethyl acetate during ozonation.

The present paper focuses on the biofilm composition and pattern of biomass in gas biofiltration of ethyl acetate working under continuous addition of ozone (O3). Two biofilters were operated for 230days, one under continuous addition of O3 (90ppbv) and another one without. Throughout the operation time, the extracellular polymeric substances (EPS), the main components in the extracellular matrix (ECM), were extracted from the biofilm and characterized qualitatively using Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) and quantitatively by analyzing its main constituents: carbohydrates, proteins, and glucuronic acid. To date, EPS characterization has been attempted mainly with biofilm aggregates related to water treatment, not air biofiltration. The results of this study may be helpful and provide more information about EPS structure when O3 was added. O3 addition only affected the amount of EPS and not its composition. The greater effect was observed on carbohydrate content since it is the main component in EPS. The EPS/biomass ratio measured was twice lower with O3 addition. Higher removal efficiency (RE) and mineralization rates were obtained with the biofilter subjected to O3 addition, and a smaller volume of a reactor would be necessary to treat all contaminant under this condition. EPS content is only quantitatively reduced by O3 addition, and at the low O3 concentration applied, no structural alteration is noted regarding the composition of the EPS.

Construction of lubricant composite coating on Ti6Al4V alloy using micro-arc oxidation and grafting hydrophilic polymer

To improve the tribological properties of Ti6Al4V alloy to realize the application in artificial joints, a novel composite coating was designed and fabricated on its surface through the combination of two different surface modification techniques—micro-arc oxidation (MAO) and grafting hydrophilic polymer. The characterizations of morphologies and composition of MAO layer were examined using scanning electron microscopy (SEM), energy dispersive spectroscope (EDS) and X-ray diffraction (XRD). It was found that a TiO2 layer displaying uniform porous structure formed on the surface based on the optimal MAO parameters of an oxidation voltage of 450 V and an oxidation time of 60 min. After grafting 3-dimethyl(3-(N-methacrylamido)propyl) ammonium propane sulfonate (MPDSAH), Fourier-transform infrared spectroscopy with attenuated total reflection (FT-IR/ATR) and wettability test demonstrated the successful modification. Tribological performance of composite coating-modified Ti6Al4V alloy in water exhibited the low friction coefficient of 0.13 and favorable wear resistance.

Preparation and Characterization of Immobilized Molybdenum Complex on Pillared Montmorillonite K-10

This study was carried out to immobilize molybdenyl (VI) acetylacetonate (MoO2(acac)2) complex on alumina pillared montmorillonite K-10 (MMT K-10). Pillar MMT K-10 was produced by introducing MMT K-10 with a hydrolysis solution of NaOH with AlCl3. Different concentrations of pillaring solution were prepared in terms of OHto Al3+ ratio (0.5, 1.0, 1.5 and 2.0) to observe the structural characteristics of MMT K-10. The pillared materials were then immobilized with 0.1 M MoO2(acac)2 and were characterized using X-ray diffractometry (XRD), scanning electron microscopy coupled in an energy dispersive X-ray spectrometer (SEM-EDX) and Fourier transform infrared spectroscopy with attenuated total reflection (FTIR-ATR) techniques. FTIR bands at ca. 890 – 930 cm-1 indicate that the Mo complex was immobilized on the surface of pillared MMT K-10 not in between the layers. This is supported by the SEM and XRD analysis where the SEM micrograph showed deposition of Mo on the surface of MMT K-10 as well as no modification of basal spacing was observed by XRD. Meanwhile, the d(001) spacing of the alumina pillared MMT K10 samples were seen to increase slightly as the concentration of OH/Al3+ increased.

Enhanced interfacial interaction and antioxidative behavior of novel halloysite nanotubes/silica hybrid supported antioxidant in styrene-butadiene rubber

A novel antioxidant (HS-s-RT) to improve the mechanical properties and anti-aging performance of styrene-butadiene (SBR) composites was prepared by antioxidant intermediate p-aminodiphenylamine (RT) grafting on the surface of halloysite nanotubes/silica hybrid (HS) via the linkage of silane coupling agent. The analysis of SEM and rubber processing analyzer (RPA) demonstrated HS-s-RT was uniformly dispersed in SBR, and stronger interfacial interaction between HS-s-RT and SBR was formed. Consequently, SBR/HS-s-RT composites have improving mechanical properties. Furthermore, the test of the retention of mechanical properties, Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR), and oxidation induction time (OIT) showed HS-s-RT can effectively improve the anti-aging effect of SBR composites than corresponding low molecular-weight antioxidant N-isopropyl-N′-phenyl-4-phenylenediamin (4010NA). Then, the mechanism of thermo-oxidative aging of SBR/HS composites was also investigated, and the superior antioxidative efficiency is attributed to the uniform dispersion and excellent migration resistance of HS-s-RT. Hence, this novel antioxidant might open up new opportunities for the fabrication of high-performance rubber composites due to its superior anti-aging effect and reinforcement.

Extraction of Eucalyptus leaves using solvents of distinct polarity. Cluster analysis and extracts characterization

Extracts of Eucalyptus globulus leaves were produced and characterized aiming their enrichment in natural bioactive compounds such as triterpenic acids (TTAs). Soxhlet (methanol, ethanol and dichloromethane) and supercritical (CO2 with/without ethanol) extractions performed under different conditions were assessed by the total extraction yield, TTAs extraction yield, and extracts concentration, and the results were compared to published data for bark and/or leaves of other species. A fast and simple dewaxing pretreatment of the leaves was implemented and its influence on extract production was evaluated. The various extracts, the leaves and the pure TTAs were analyzed by Fourier Transform Infra-Red spectroscopy with Attenuated Total Reflectance (FTIR-ATR) and Gas Chromatography-Mass Spectroscopy (GC–MS), and the data thoroughly discussed by chemometric methods. Overall, this work provides guidelines for the production of natural extracts enriched in triterpenic acids.

LDPE Oxidation by CO2 Laser Radiation (10.6 µm)

Thermooxidation of LDPE films by CO2 laser radiation, 10.6 μm, was characterized by Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR). The formation of carbonyl and hydroxyl functional groups onto LDPE films was dependent on the fluency of CO2 laser. IR absorption of vinyl groups and C-O bond present in alcohols showed a decrease and an increase, respectively, indicating that CO2 laser radiation causes simultaneous formation and accumulation of hydroperoxides in LDPE films; furthermore, crystallinity of LDPE films irradiated with CO2 tends to increase. So, CO2 laser radiation is able to oxidize the LDPE films, obtaining a PE with similar spectroscopic properties to that of PE-BIO by a physical process.

Silver nanoparticles supported on polyethylene glycol/cellulose acetate ultrafiltration membranes: preparation and characterization of composite

In this research work, silver nanoparticles/polyethylene glycol/cellulose acetate ultrafiltration (Ag-NPs/PEG/CA UF) composite membranes were synthesized and characterized. The Ag-NPs were embedded in the polymer matrix by two methods: in situ and ex situ; varying the type of solvent used (dimethylformamide, DMF; or N-methyl-2-pyrrolidone, NMP). The Ag-NPs used in the ex situ method were synthesized by a green chemistry reduction method. The composite membranes were characterized by Fourier transform infrared spectroscopy with attenuated total reflection (FTIR-ATR), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), and thermogravimetric analysis-derivative thermogravimetric analysis (TGA-DTG); the molecular weight cut-off and permeability were also determined. Moreover, the antibacterial efficiency of the composite membranes was measured against bacteria like Escherichia coli and Staphylococcus aureus. By FTIR-ATR analysis it was possible to observe that the Ag-NPs embedded in membranes changed the membrane morphology. The SEM-EDS analysis showed that the in situ composite membranes have good dispersity of Ag-NPs, DMF FB being the most densely populated obtained. By another hand, the ex situ DMF NP composite membrane presented the highest amount of silver signals per unit area (µm2). The permeability of the membrane was affected by the presence of the Ag-NPs; the DMF NP composite membrane had the highest permeate flow, while DMF FB had the highest antibacterial activity.

The Authentication of Halal Dental Materials Using Rapid Fourier Transform Infrared (FTIR) Spectroscopy

The purpose of this study is to detect the presence of gelatin in orthodontic dental materials for halal authentication. The detection of gelatins was done using Fourier Transform Infrared Spectroscopy with Attenuated Total Reflectance (FTIR-ATR). In this study, 21 samples were included and the spectrums were generated by OMNIC software of Nicolet iS50 FTIR. All data were also subjected to similarity match (SM) using TQ Analyst software. Four types of gelatin tested, namely porcine, bovine, fish and commercialized gelatin. From the studies, it was found that no samples exhibit similar spectra as the gelatins tested and SM found that no samples showed 100% similarities with porcine gelatin.

Evaluation of the oxalic and tartaric acids as an alternative to citric acid in aqueous cleaning systems for the conservation of contemporary acrylic paintings

Abstract Today, acrylic emulsion paint is widely used in the artistic area as an alternative to the traditional oil painting. However, after a short time of painting exposure to the environment, the acrylic tends to accumulate surface dirt for inherent reasons to its composition. This phenomenon creates a conservation problem, because the usual cleaning methods are hindered by the acrylic film soft morphology and its high sensitivity to organic solvents. To date, few aqueous solutions based cleaning systems have been investigated as alternatives to the traditional methods. This paper proposes the use of oxalic and tartaric acid solutions for acrylic paints cleaning as alternatives to citric acid. A series of titanium white acrylic paint films were subjected to immersion tests in different aqueous solutions and their weight change was monitored to determine the effects produced by the solutions according to pH (3.5, 5 and 8.5) and conductivity (4, 6 and 12 mS cm−1). Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR), X-ray diffraction (XRD), and scanning electron microscopy (SEM-EDX) techniques were used to evaluate the acids effects on the films before and after the tests. The results obtained showed that oxalic and tartaric acids exhibit similar properties to citric acid, resulting as a valid alternative for aqueous cleaning treatments on acrylic paintings.

Compressive stress relaxation modeling of butadiene rubber under thermo‐oxidative aging

ABSTRACTThe compressive stress relaxation tests of butadiene rubber (BR) at different thermo‐oxidative aging temperatures were carried out. Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR‐ATR) was used to observe the variations of internal groups before and after the thermo‐oxidative aging. Magnetic resonance‐crosslink density (MR‐XLD) spectroscopy was used to measure the crosslink densities. The results showed the compressive stress relaxation of BR during thermo‐oxidative aging was dominated by chemical reactions: crosslinking, chain scission, and oxidation. Then an empirical model and an amendatory standard linear solid (SLS) model were put forward to describe the compressive stress relaxation behavior of BR. Both models fitted the data well. The SLS model, based on the aging mechanism of BR, not only made up the disadvantages of the empirical model, but also considered the changes of intrinsic viscosity (η) during the thermo‐oxidative aging of BR. The SLS model showed that the thermo‐oxidative aging of BR was mainly dominated by the crosslinking and oxidation reactions. This research proposes the amendatory SLS model and has important significance for study the stress relaxation behavior of crosslinked rubbers during thermo‐oxidative aging. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44630.

Ultra-lubricated surface of Ti6Al4V fabricated with combination of porous TiO2 layer, ultra-high molecular weight polyethylene film and hydrophilic polymer brushes

With the purpose of achieving ultra-lubricated surface on Ti6Al4V alloy, porous TiO2 layer, ultra-high molecular weight polyethylene (UHMWPE) film and hydrophilic 3-dimethyl(3-(N-methacrylamido)propyl)ammonium propane sulfonate (DMMPPS) polymer brushes were sequentially fabricated to form a composite coating. The change of surface morphology was investigated by Scanning Electron Microscope (SEM) during the preparation of composite coating. The composition and structure of modified surface were characterized by Energy Dispersive Spectrometry (EDS), X-ray Diffraction (XRD) and Fourier-transform Infrared Spectroscopy with Attenuated Total Reflection (FTIR/ATR). The surface wettability was also studied to evaluate the hydrophilicity. Friction and wear properties of modified alloys sliding against stainless steel were preliminarily tested by a ball-on-disc tribometer in physiological saline. The results revealed that the composite coating with well hydrophilicity on Ti6Al4V alloy was successfully prepared. The modified surface presented an ultra-low friction coefficient at 0.02, and simultaneously indicated favorable wear resistance. This newly developed composite coating possessed potential to improve the tribological properties of Ti6Al4V alloy.

Antioxidative behavior of a novel samarium complex in styrene-butadiene rubber/silica composites

The focus of this study was on the thermo-oxidative aging resistance of a new rare earth complex, samarium lysine dithiocarbamate (Sm-LDC), in the styrene-butadiene rubber (SBR)/silica composites. The anti-aging behavior of SBR/silica composites with Sm-LDC, as well as several common commercial antioxidants, was systematically investigated by oxidation induction time (OIT), mechanical testing, crosslink density determination, Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR), and thermo-gravimetric analysis (TGA). The results demonstrated that Sm-LDC significantly improve the thermo-oxidative stability of SBR/silica composites and protect the composites against the thermo-oxidative aging more effectively than the widely used antioxidant 4010NA and antioxidant MB in rubber industry. It could be attributed to the synergistic effect between dithiocarboxyl groups and samarium ions in Sm-LDC, which can high-efficiently decompose the hydroperoxide and scavenge the oxy radicals, respectively. Besides, the results of whiteness and yellowness index (Y.I.) analysis indicated that Sm-LDC can hardly cause discoloration to the SBR/silica composites and is better than the recognized light-colored antioxidant MB in the aspect of color. This research might open up new opportunities for preparing highly thermo-oxidative aging-resistant rubber composites without color contamination.