From Fourier Transform Infrared Spectra Research Articles

Challenges of Raman spectra to estimate carbonyl index of microplastics: A case study with environmental samples from sea surface

This study investigates the feasibility of using the carbonyl index (CI) derived from Raman spectra as an indicator of plastic degradation and its relationship with the CI calculated from Fourier transform infrared (FTIR) spectra, using microplastic samples of polyethylene (PE) from surface seawater. Multiple methods were used to calculate the CI values of FTIR spectra, while proposed methods were used to calculate the corresponding CI values of Raman spectra. Some significant relations between FTIR CI and Raman CI were observed. However, small R2 values suggest weak functional relationships, which can be attributed to the low signal-to-noise ratio (SNR) of Raman spectra. These results highlight the challenges of establishing a functional relationship between FTIR CI and Raman CI, including challenges such as the uniformity of Raman spectra, determining optimal Raman measurement parameters, selecting appropriate peaks for Raman CI calculation, deciding on spectral processing methods, and addressing the interdependence of these issues.

Optoelectronic and Structural Properties of Plasma Deposited Nanocrystalline Hydrogenated Silicon Oxide Thin Films

To develop wide bandgap materials for solar cells and other optoelectronic devices, undoped hydrogenated silicon oxide (SiOx:H) thin films are prepared by conventional radio frequency plasma enhanced chemical vapor deposition (RF PECVD) method. The variation of carbon dioxide dilution ([Formula: see text]) on optoelectronic and structural properties are studied thoroughly by keeping silane and hydrogen gas flow fixed. Surface morphology of the SiOx:H films have been studied by Field Emission Scanning Electron Microscopy (FESEM) and Atomic Force Microscopy (AFM). Distinct silicon nanocrystallites of average diameter [Formula: see text] 3–6[Formula: see text]nm embedded uniformly in amorphous SiOx network have been observed in high resolution Transmission Electron Microscopy (HRTEM). From Fourier Transform Infrared spectra (FTIR), it is observed that oxygen content ([Formula: see text]) increases initially with [Formula: see text] and afterwards it decreases. Strong room temperature photoluminescence (PL) peak is obtained for the as-deposited films having lower oxygen content ([Formula: see text]). The origin of room temperature PL spectra and its correlation with [Formula: see text] can be explained by quantum confinement effect (QCE) theory.

A fuzzy graph approach analysis for COVID-19 outbreak

Complex systems require rigorous analysis using effective method, in order to handle and interpret their information. Spectrum produced from Fourier transform infrared (FTIR) instrument is an example of a complex system, due to their overlapped bands and interactions within the spectrum. Thus, chemometrics techniques are required to further analyze the data, in particular, chemometrics fuzzy autocatalytic set (c-FACS). The c-FACS is initially used to analyze the FTIR spectra of gelatins. However, in this study, the c-FACS is generalized and implemented for analysis of Coronavirus disease 2019 (Covid-19), particularly, the pandemic outbreak in Malaysia. The daily Covid-19 cases in states in Malaysia are modeled and analyzed using c-FACS, to observe the trend and severity of the disease in Malaysia. As a result, the classification of severity of zones in Malaysia are identified. The obtained results offer descriptive insight for strategizing purposes in combating the Covid-19 outbreak in Malaysia.

Spectral Aerosol Optical Depth Retrievals by Ground-Based Fourier Transform Infrared Spectrometry

Aerosol Optical Depth (AOD) and the Ångström Exponent (AE) have been calculated in the near infrared (NIR) and short-wave infrared (SWIR) spectral regions over a period of one year (May 2019–May 2020) at the high-mountain Izaña Observatory (IZO) from Fourier Transform Infrared (FTIR) solar spectra. The high-resolution FTIR measurements were carried out coincidentally with Cimel CE318-T photometric observations in the framework of the Aerosol Robotic Network (AERONET). A spectral FTIR AOD was generated using two different approaches: by means of the selection of seven narrow FTIR micro-windows (centred at 1020.90, 1238.25, 1558.25, 1636.00, 2133.40, 2192.00, and 2314.20 nm) with negligible atmospheric gaseous absorption, and by using the CE318-AERONET’s response function in the near-coincident bands (1020 nm and 1640 nm) to degrade the high-resolution FTIR spectra. The FTIR system was absolutely calibrated by means of a continuous Langley–Plot analysis over the 1-year period. An important temporal drift of the calibration constant was observed as a result of the environmental exposure of the FTIR’s external optical mirrors (linear degradation rate up to 1.75% month−1). The cross-validation of AERONET-FTIR databases documents an excellent agreement between both AOD products, with mean AOD differences below 0.004 and root-mean-squared errors below 0.006. A rather similar agreement was also found between AERONET and FTIR convolved bands, corroborating the suitability of low-resolution sunphotometers to retrieve high-quality AOD data in the NIR and SWIR domains. In addition, these results demonstrate that the methodology developed here is suitable to be applied to other FTIR spectrometers, such as portable and low-resolution FTIR instruments with a potentially higher spatial coverage. The spectral AOD dependence for the seven FTIR micro-windows have been also examined, observing a spectrally flat AOD behaviour for mineral dust particles (the typical atmospheric aerosols presented at IZO). A mean AE value of 0.53 ± 0.08 for pure mineral dust in the 1020–2314 nm spectral range was retrieved in this paper. A subsequent cross-validation with the MOPSMAP (Modeled optical properties of ensembles of aerosol particles) package has ensured the reliability of the FTIR dataset, with AE values between 0.36 to 0.60 for a typical mineral dust content at IZO of 100 cm−3 and water-soluble particle (WASO) content ranging from 600 to 6000 cm−3. The new database generated in this study is believed to be the first long-term time series (1-year) of aerosol properties generated consistently in the NIR and SWIR ranges from ground-based FTIR spectrometry. As a consequence, the results presented here provide a very promising tool for the validation and subsequent improvement of satellite aerosol products as well as enhance the sensitivity to large particles of the existing databases, required to improve the estimation of the aerosols’ radiative effect on climate.

Structural and magnetic properties of single domain CoFe2O4 magnetic nanoparticles dispersed in SiO2 matrix

Uniformly dispersed CoFe2O4 nanoparticles in SiO2 matrix have been synthesized in two-step process by a co-precipitation route at lower temperature (70 °C). Phase purity and average crystallite size of cobalt ferrite (CFO) and CoFe2O4 nanoparticles dispersed in SiO2 matrix (Si-CFO) have been evaluated to be 17.6 nm and 15.2 nm respectively. Bond edges and bond lengths were evaluated from Rietveld refinment confirms the existence of compressed and tensile strain in CFO and Si-CFO nanoparticles. The average particle sizes evaluated from transmission electron microscope (TEM) were found to be 16 and 17.3 nm respectively. Functional groups present in CFO and Si-CFO nanoparticles were investigated from Fourier transform infrared spectra (FTIR). Magnetic properties were investigated by vibrating sample magnetometry (VSM). Lower saturation magnetization (25.6) with enhanced coercivity (977) at room temperature has been observed for Si-CFO nanoparticles and attributed to the increased number of disordered surface spins with reduced effective magnetic anisotropy, enhanced stress and surface anisotropy. Strain in CFO and Si-CFO nanoparticles have been evaluated from magnetic measurements and corroborate well with the strain evaluated from Williamson-Hall-Isotropic strain model (W-H-ISM) and Williamson-Hall-Anisotropic strain model (W-H-ASM). Effect of specific saturation magnetization specific surface area and dead magnetic layer thickness on magnetic properties of pristine CFO and Si-CFO nanoparticles have been investigated. The enhanced specific surface area and dead magnetic layer thickness resulted in increased strain in Si-CFO with reduced saturation magnetization. The dead layer thickness is evaluated to be 1.34 nm and 1.96 nm for CFO and Si-CFO nanoparticles respectively.

Feasibility assessment of phenotyping cotton fiber maturity using infrared spectroscopy and algorithms for genotyping analyses

BackgroundCotton fiber maturity is an important property that partially determines the processing and performance of cotton. Due to difficulties of obtaining fiber maturity values accurately from every plant of a genetic population, cotton geneticists often use micronaire (MIC) and/or lint percentage for classifying immature phenotypes from mature fiber phenotypes although they are complex fiber traits. The recent development of an algorithm for determining cotton fiber maturity (MIR) from Fourier transform infrared (FT-IR) spectra explores a novel way to measure fiber maturity efficiently and accurately. However, the algorithm has not been tested with a genetic population consisting of a large number of progeny plants.ResultsThe merits and limits of the MIC- or lint percentage-based phenotyping method were demonstrated by comparing the observed phenotypes with the predicted phenotypes based on their DNA marker genotypes in a genetic population consisting of 708 F2 plants with various fiber maturity. The observed MIC-based fiber phenotypes matched to the predicted phenotypes better than the observed lint percentage-based fiber phenotypes. The lint percentage was obtained from each of F2 plants, whereas the MIC values were unable to be obtained from the entire population since certain F2 plants produced insufficient fiber mass for their measurements. To test the feasibility of cotton fiber infrared maturity (MIR) as a viable phenotyping tool for genetic analyses, we measured FT-IR spectra from the second population composed of 80 F2 plants with various fiber maturities, determined MIR values using the algorithms, and compared them with their genotypes in addition to other fiber phenotypes. The results showed that MIR values were successfully obtained from each of the F2 plants, and the observed MIR-based phenotypes fit well to the predicted phenotypes based on their DNA marker genotypes as well as the observed phenotypes based on a combination of MIC and lint percentage.ConclusionsThe MIR value obtained from FT-IR spectra of cotton fibers is able to accurately assess fiber maturity of all plants of a population in a quantitative way. The technique provides an option for cotton geneticists to determine fiber maturity rapidly and efficiently.

Structural morphological and electrochemical studies on PMMA/PVP blends

Abstract A special attention has been focused on the development of Polymer blends in recent years. It is a member of a class of materials analogous to metal alloys, in which at least two polymers are blended together to create a new material with different properties. In the present study, Poly(methyl methacrylate) (PMMA) /Polyvinylpyrrolidone(PVP) blends with different weight ratios were prepared by sol gel method using chloroform. The blend formation has been confirmed from Fourier transform infrared (FTIR) and X-ray diffraction (XRD). Electrochemical performance of polymer blends were analyzed using 3.5% NaCl. The crystallnity of PVA/PVP blends decreases with the increase in concentration of PVP. The FTIR spectra showed the blending of PMMA and PVP at different weight ratios.

Effect of inlet air drying temperatures on the physicochemical properties and antioxidant activity of whey protein isolate-kale leaves chlorophyll (WPI-CH) microcapsules

The whey protein isolate-kale leaves chlorophyll (WPI-CH) microcapsules were prepared by spray drying in this work. Results from Fourier transform infrared spectra (FT-IR) showed that WPI-CH microcapsules were successfully obtained by forming the hydrogen bonds between WPI and chlorophyll, which resulted in shifting of the absorption band at 1074 cm−1 to 1078 cm−1 with a new absorption band revealed in 1049 cm−1. Effect of inlet air drying temperatures on the physicochemical properties and antioxidant activity of WPI-CH microcapsules were investigated. The result revealed that the moisture content of WPI-CH (20% addition) microcapsule was decreased by 21.1% with the inlet air drying temperature increased from 120 to 180 °C. Moreover, the encapsulation efficiency and solubility of chlorophyll were enhanced by 3.78% and 7.79%, respectively. Furthermore, DPPH scavenging capacity of WPI-CH microcapsules under different addition of chlorophyll were increased from 42.9% to 74.3%, 52.7%–82.7% and 71.8%–85.3%, respectively.

A co-assembled gel of a pyromellitic dianhydride derivative and polyaniline with optoelectronic and photovoltaic properties.

5,5'-(1,3,5,7-Tetraoxopyrrolo[3,4-f]isoindole-2,6-diyl)diisophthalic acid (PMDIG) is used to produce a supramolecular hydrogel via acid-base treatment. The field emission scanning electron micrograph and atomic force microscopy micrographs exhibit a fibrillar network structure from intermolecular supramolecular interaction, supported from Fourier transform infrared (FTIR) and UV-vis spectra. The fluorescence intensity of the PMDIG gel is 16 times higher than that of the sodium salt of PMDIG with a 42 nm red shift of the emission peak. Upon addition of an anilinium chloride solution to the PMDIG gel, it transforms into the sol, and when a solid ammonium persulfate is spread over it, a stable hydrogel is produced. The co-assembled PMDIG-polyaniline (PANI) gel exhibits a fibrillar network morphology, and the co-assembly is formed by the supramolecular interaction between the polyaniline (donor) and the PMDIG (acceptor) molecules, which is evident from FTIR spectra and wide angle X-ray scattering results. The UV-vis spectrum of the PMDIG-PANI hydrogel exhibits the characteristic peaks of polaron band transitions of the doped PANI. The PMDIG-PANI co-assembled hydrogel has a 51-fold higher storage modulus, a 52-fold higher elasticity, a 1.4-fold increase in stiffness, and a 5-fold increase of fragility compared to the values of the PMDIG hydrogel. The PMDIG-PANI xerogel exhibits a 4 order of magnitude increase in dc conductivity compared to that of PMDIG, and the I-V characteristic curve exhibits a rectification property under white light illumination showing photocurrent rectification, a new phenomenon reported here for the supramolecular gel systems. A dye-sensitized solar cell fabricated with an ITO/PMDIG-PANI/graphite device shows a power conversion efficiency (η) of 0.1%. A discussion of the mechanism of gel formation and the sol state of the PMDIG-aniline system is included considering the contact angle values of the xerogels.

Structural Study of Asphaltenes from Iranian Heavy Crude Oil

In the present study, asphaltene precipitation from Iranian heavy crude oil (Persian Gulf off-shore) was performed using <i>n<i/>-pentane (<i>n<i/>-C<sub>5<sub/>) and <i>n<i/>-heptane (<i>n<i/>-C<sub>7<sub/>) as light alkane precipitants. Several analytical techniques, each following different principles, were then used to structurally characterize the precipitated asphaltenes. The yield of asphaltene obtained using <i>n<i/>-pentane precipitant was higher than asphaltene precipitated with the use of <i>n<i/>-heptane. The asphaltene removal affected the <i>n<i/>-C<sub>5<sub/> and <i>n<i/>-C<sub>7<sub/> maltene fractions at temperatures below 204°C, as shown by the data obtained through the simulated distillation technique. Viscosity of heavy oil is influenced by the asphaltene content and behavior. The viscosity dependence of the test heavy oil on the shear rate applied was determined and the flow was low at y. above 25 s<sup>-1<sup/> . The reconstituted heavy oil samples were prepared by adding different amounts of asphaltenes to the maltenes (deasphalted heavy oil) and asphaltene effects were more pronounced at the low temperature of 25°C as compared with those at the higher temperatures. According to the power law model used in this study the flowability of the test heavy oil exhibited a pseudoplastic character. Structural results obtained from Fourier Transform InfraRed (FTIR) spectroscopy showed the presence of the different functional groups in the precipitated asphaltenes. For instance, the presence of different hydrocarbons (aliphatic, aromatic and alicyclic) based on their characteristics in the FTIR spectra was confirmed. Resins are effective dispersants, and removal of this fraction from the crude oil is disturbing to the colloidal nature of heavy oil; asphaltene flocculation and precipitation eventually occur. Appearance of pores in the Scanning Electron Microscopy (SEM) images was used as an indicator of the resin detachment. With the use of <sup>1<sup/>H and <sup>13<sup/>C Nuclear Magnetic Resonance (NMR) spectroscopy, two important structural parameters of the asphaltenes were determined. Namely, the aromaticity (fa) and the average number of carbon atoms per alkyl side chain (<i>n<i/><sub><i>carbon<i/><sub/>), where <i>f<sub>a<sub/><i/> for <i>n<i/>-C<sub>5<sub/> asphaltenes was lower (0.39) than that obtained with <i>n<i/>-C<sub>7<sub/> solvent (0.49). Additionally, the <i>n<i/><sub><i>carbon<i/><sub/> parameter values were 7.7 and 5.7 for <i>n<i/>-C5 and <i>n<i/>-C<sub>7<sub/> asphaltenes, respectively. Structural recognition of the oil constituents is the prerequisite of different techniques usable for heavy oil upgrading.

Unconventional Method for Monitoring of Waste Cooking Oil Transesterification

A technique to monitor transesterification of waste cooking oil (WCO) is presented. The technique was developed based on analogue signal from WCO, fatty acid methyl ester (FAME) and commercial palm oil (CPO). A low-pass filter design for the photodiode was used to obtain the characteristic analog signal generated by these oil samples and the signal was correlated to absorbance spectra of the oils using data from Fourier transform infrared (FTIR) equipment. A match was made between the analogue signals of the oil samples and calibrated against the FTIR spectra at 95% confidence level. Depletion of WCO during transesterification in a batch reactor correlated with the time observed for peak yield during biodiesel production. The results of the technique are discussed as a possible way to monitor transesterification process in a batch reactor.

A new statistical approach for determining the crystallinity of heat-altered bone mineral from FTIR spectra

The crystallinity of bone mineral represents an established method of measuring heat-induced change and is of importance to fields including material science, clinical science, anthropology and archaeology. A commonly used technique involves the calculation of the Crystallinity Index (CI) using selected peaks from Fourier Transform Infrared (FTIR) absorbance spectra. However, the choice of peaks has to date not been statistically justified. In this study a novel application of statistical techniques to the FTIR spectra of bone samples burned in the range 100 °C–1100 °C has been used to identify 5 new spectral indices of heat-induced crystallinity change. The validity of the new indices was tested by using a statistical classification model (LDA) to predict the burning temperature of a set of 108 bone samples burned between 100 °C and 1100 °C. A correct classification rate (CCR) of 97.2% was obtained when a combination of 4 indices including the CI was used. This was significantly better than the CCR of 66.7% which was obtained when the CI was used on its own.

Synthesis and characterization of a magnetic hybrid material consisting of iron oxide in a carboxymethyl cellulose matrix

AbstractA magnetic hybrid material (MHM), consisting of iron‐oxide nanoparticles (˜4 nm) embedded in sodium carboxymethyl cellulose (Na‐CMC) matrix was synthesized. The MHM synthesis process was performed in two stages. First, a precursor hybrid material (Fe(II)‐CMC) was synthesized from two aqueous solutions: Na‐CMC solution and FeCl2 solution. In the second stage, the precursor hybrid material was treated with H2O2 under alkaline conditions to obtain the MHM. The results obtained from X‐ray diffraction show that the crystalline structure of iron oxide into MHM corresponds to maghemite or magnetite phase. Conversely, the results obtained from Fourier transform infrared (FTIR) spectroscopy reveal that the polymeric matrix (Na‐CMC) preserves its chemical structure into the MHM. Furthermore, in FTIR spectra are identified two characteristic bands at 570 and 477 cm−1 which can be associated to maghemite phase. Images obtained by high resolution transmission electron microscopy and bright field scanning transmission electron microscope show that iron‐oxide nanoparticles are embedded in the Na‐CMC. Magnetic properties were measured at room and low temperature using a quantum design MPMS SQUID‐VSM magnetometer. Diagrams of magnetization versus temperature show that iron‐oxide nanoparticles embedded in Na‐CMC have a superparamagnetic‐like behavior. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Impact of sucrose level on storage stability of proteins in freeze-dried solids: I. correlation of protein–sugar interaction with native structure preservation

The purpose of this study is to investigate protein–sugar interactions in dried protein solids as a function of sucrose level using water sorption isotherm data and secondary structure information from Fourier transform infrared (FTIR) spectroscopy. Three IgG1 fusion proteins and two cytokines were freeze-dried with sucrose at different sucrose/protein mass ratios. The water monolayer of the colyophilized sucrose/protein samples, as determined by BET analysis of water sorption data, was found to be lower than that expected based on additive contributions of pure protein and pure sucrose. This negative deviation suggests the presence of a solid-state interaction between protein and sucrose that reduces the availability of total water-binding sites. The difference in water monolayer between colyophilized and a physical mixture of protein and sucrose reached a maximum value at sucrose/protein mass ratio of 1/1 for these proteins, suggesting saturation of the protein–sugar interaction at this ratio. In addition, for four proteins studied, the normalized peak height of the major band in the FTIR spectra reached a plateau at about a 1/1 mass ratio. Therefore, it appears that there is a coupling between the preservation of protein secondary structure and the protein–sugar interaction as measured by water sorption isotherms. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:3131–3144, 2009

Chemistry at Air/Water Interface versus Reaction in a Flask: Tuning Molecular Conformation in Thin Films

Atomic force microscopy and X-ray reflectivity studies of cobalt stearate Langmuir-Blodgett (LB) films (CoStp) deposited from a preformed bulk sample on quartz substrates showed formation of a Volmer-Weber type monolayer but no multilayers as compared to the excellent multilayers of cobalt stearate films (CoStn) deposited at the air/water interface by the usual LB technique, in spite of both showing bidentate bridging type coordination of cobalt ions with the carboxylate group. The difference is attributed to existence of different headgroup conformers, observed from Fourier transform infrared (FTIR) studies. The CoStp films had a higher energy 'boat' conformation with linear O-Co-O linkage, whereas CoStn formed a low energy conformer with a bent O-Co-O configuration (bond angle of 105 degrees). Present results support the necessity of bidentate bridging coordination in multilayer deposition, but rejects its sufficiency by bringing out the crucial role played by air/water interface. Differences in surface pressure-molecular area isotherms and hydrocarbon tail-tail interactions (evident from FTIR spectra) of the films support the above statement. Methyl-methyl interactions observed in CoStn samples suggest hierarchy of supramolecular chemistry at the air/water interface in tuning the C-O-Co bond angle essential to satisfy the wetting condition with the substrate and subsequently form LB multilayers.

Detecting the quality of glycerol monolaurate: A method for using Fourier transform infrared spectroscopy with wavelet transform and modified uninformative variable elimination

Glycerol monolaurate (GML) products contain many impurities, such as lauric acid and glucerol. The GML content is an important quality indicator for GML production. A hybrid variable selection algorithm, which is a combination of wavelet transform (WT) technology and modified uninformative variable eliminate (MUVE) method, was proposed to extract useful information from Fourier transform infrared (FT-IR) transmission spectroscopy for the determination of GML content. FT-IR spectra data were compressed by WT first; the irrelevant variables in the compressed wavelet coefficients were eliminated by MUVE. In the MUVE process, simulated annealing (SA) algorithm was employed to search the optimal cutoff threshold. After the WT-MUVE process, variables for the calibration model were reduced from 7366 to 163. Finally, the retained variables were employed as inputs of partial least squares (PLS) model to build the calibration model. For the prediction set, the correlation coefficient ( r) of 0.9910 and root mean square error of prediction (RMSEP) of 4.8617 were obtained. The prediction result was better than the PLS model with full-spectra data. It was indicated that proposed WT-MUVE method could not only make the prediction more accurate, but also make the calibration model more parsimonious. Furthermore, the reconstructed spectra represented the projection of the selected wavelet coefficients into the original domain, affording the chemical interpretation of the predicted results. It is concluded that the FT-IR transmission spectroscopy technique with the proposed method is promising for the fast detection of GML content.

Extended Multiplicative Signal Correction as a Tool for Separation and Characterization of Physical and Chemical Information in Fourier Transform Infrared Microscopy Images of Cryo-Sections of Beef Loin

Extended multiplicative signal correction (EMSC) is used to separate and to characterize physical and chemical information in spectra from Fourier transform infrared (FT-IR) microscopy. This appears especially useful for applications in infrared spectroscopy where the scatter variance in spectra changes with the chemical variance in the sample set. In these cases the chemical information of specific bands that are assigned to functional groups is easier to interpret when the scatter information is removed from the spectra. We show that scatter (physical) information in FT-IR spectra of heat-treated beef loin is related to chemical changes due to heat treatment. This information is caused by textural changes induced by the heat treatment and expressed by physical effects as the optical path length. The chemical absorbance changes introduced in the FT-IR spectra due to heat treatment are shifts in the protein region of the infrared spectrum caused by changes in the secondary structure of the proteins. If the scatter and the chemical information is not separated properly, scatter information may erroneously be interpreted as chemical information.

Preparation and characterization of nanometer perovskite-type complex oxides LaMnO 3.15 and their application in catalytic oxidation

LaMnO 3+ δ nanocrystalline powders were prepared using a new method in which the insoluble carboxyl-containing grafted starch copolymer (ISC) with a 3D tangled network was used to adsorb metal ions by carboxyl and form precursors. The structural components in the ISC and the precursors were identified from Fourier transform infrared spectra (FT-IR) of the samples. Thermogravimetric-differential thermal analysis (TG-DTA) for the precursors gave the detail of their decomposition in the dry air. The crystalline phase of LaMnO 3.15 was characterized by X-ray diffraction (XRD). The shape and size distribution of particles were observed by transmission electron microscopy (TEM). The resultant nanoparticles were firstly used as catalysts for selective oxidation in solution and exhibited evidently catalytic activity for oxidation of cinnamaldehyde at moderate temperatures.

Automatic amide I frequency selection for rapid quantification of protein secondary structure from Fourier transform infrared spectra of proteins.

Here we report the development of a new neural network based approach for rapid quantification of protein secondary structure from Fourier transform infrared (FTIR) spectra of proteins. A technique for efficiently reducing the amount of spectral data by almost 90% is suggested to facilitate faster neural network analysis. Additionally, an automatic procedure is introduced for selecting only those regions within the amide I band of protein FTIR spectra, which can be best related to secondary structure contents by subsequent neural network analysis. Based on a given reference set of FTIR spectra from proteins with known secondary structure, a subset of merely 29 out of 101 amide I absorbance values could be identified, which lead to an improved prediction accuracy. The average prediction accuracy achieved for helix, sheet, turn, bend, and other is 4.96% which is better than that achieved by alternative methods that have been previously reported indicating the significant potential of this approach. Our suggested automatic amide I frequency selection procedure may be easily extended to identify promising regions from spectral data recorded by other spectroscopic techniques, like for example circular dichroism spectroscopy.

Growth, microstructure and electronic properties of amorphous carbon nitride films investigated by plasma diagnostics

Amorphous nitrogenated carbon films are prepared in a dual electron cyclotron resonance-radio frequency plasma from a mixture of methane and nitrogen gas. A marked variation of electronic properties and microstructure of the films as a function of nitrogen concentration is observed from Fourier transform infrared (FTIR) spectra, electron energy loss spectra, optical absorption spectra, x-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy and electrical conductivity. From the variation of intensity of different positive ions and neutral radicals, using quadrupole mass spectroscopy and optical emission spectroscopy, the growth rate, structure and properties of the films are investigated. The density of methyl (CH3) radicals and the film growth rate are found to decrease with the increase of nitrogen concentration. A correlation between the C/N atomic ratio in the films and CH/CN and also CH/N ratio in the plasma is noticed. Also, the CH radical intensity in the plasma and the amount of CH bonds in the films, observed from FTIR spectra, vary in a similar fashion as a function of nitrogen concentration. A model describing film growth and nitrogen incorporation in the films is proposed.