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Bone strength in human cortical bone is determined by the composition and structure of both the mineral and collagen matrices and influenced by factors such as age, gender, health, lifestyle and genetic factors. Age-related changes in the bone matrix are known to result in loss of mechanical strength and increased fragility. In this study we show how Raman spectroscopy, with its exquisite sensitivity to the molecular structure of bone, reveals new insights into age- and sex-related differences. Raman analysis of 18 samples of cortical hip bone obtained from people aged between 47–82 years with osteoarthritis (OA) found subtle changes in the lipid and collagen secondary structure, and the carbonate (CO32−) and phosphate (PO43−) mineral ratios in the bone matrix. Significant differences were observed between older and younger bones, and between older female and older male bones; no significant differences were observed between younger male and female bones. Older female bones presented the lowest mineral to matrix ratios (MMR) and highest CO32−/PO43− ratios, and relative to lipid/collagen –CH2 deformation modes at 1450 cm−1 they had lowest overall mineral content, higher collagen cross linking and lipid content but lower levels of α-helix collagen structures than older male and younger male and female bones. These observations provided further insight on bone composition changes observed in the bone volume fraction (BV/TV) for the older female bones from microCT measurements on the same samples, while tissue mineral density (TMD) measurements had shown no significant differences between the samples.

A Raman Spectroscopy probe is used to discriminate between healthy and cancerous prostate tissue. Results from ex vivo human biopsy tissue are presented. Results show excellent classification performance between the different types of tissue.

Infrared spectroscopy coupled with partial least squares (PLS) regression has been shown to be a rapid alternative to wet chemical analytical methods for determining the cell-wall compositions of wood. Both near infrared (NIR) spectroscopy, and mid-infrared spectroscopy with attenuated total reflectance Fourier transform infrared (ATR FTIR) sampling, coupled with PLS regression, can be used to quickly and accurately predict the lignin contents and monosaccharide compositions of milled wood. However, milling wood can be time consuming and laborious. In this study we demonstrate that PLS-1 models built using NIR and ATR FTIR spectra of milled Pinus radiata wood, with different sized wood particles and different moisture contents, can rapidly and accurately predict the cell-wall compositions of solid wood. A robust assessment of the prediction accuracy was conducted using a separate test set of solid wood samples with both ‘smooth’ and ‘rough’ surface finishes. The lowest standard error (SE) values for most of the compositional predictions were obtained for the ‘rough’ solid wood samples, using PLS-1 models built from NIR spectra of ‘large’ milled wood particles (0.422 mm) with ambient moisture content. The SE achieved for NIR spectroscopy prediction of lignin for the ‘rough’ solid wood was 1.91%, and for the monosaccharides, arabinose (0.37%), xylose (1.25%), galactose (2.00%), mannose (1.54%), and 4-O-methyl glucuronic acid (0.24%). The powerful combination of NIR spectroscopy with PLS regression offers an attractive method for rapid prediction of cell-wall compositions of solid wood samples, thus avoiding milling. In addition, this technique highlights the different levels of these cell-wall components in opposite and compressed regions in solid wood.

During the process of studying some morphological characters of fish found in the food of the Australasian gannet Morus serrator breeding at Horuhoru Rock and Mahuki islands in the Hauraki Gulf, New Zealand, one carangid specimen of fish species Trachurus declivis out of the 25 fish specimens examined revealed seven small plastic particles in its stomach of different colours: black, red, blue, green, and transparent. Fourier transform infrared (FTIR) spectroscopy was used to identify the compositions of the particles as low and high density polyethylene, poly (methyl methacrylate), polypropylene, and a copolymer of butadiene, acrylonitrile, and methacrylamide. The plastic particles comprised several different shapes and sizes, ranging between 4.5 and 10 mm, and are therefore categorized as micro-and mesoplastic fragments.

Vibrational signatures of three types of phytoplankton were measured using Raman spectroscopy. Characteristic shifts in pigment bands were identified as markers for phytoplankton viability while PCA of the full spectral profile allowed differentiation between phytoplankton.

Near infrared (NIR) spectroscopy coupled with partial least squares (PLS-1) regression was used to predict the lignin contents and monosaccharide compositions of milled wood of Pinus radiata. The effects of particle size and moisture content were investigated by collecting NIR spectra of four sample types: large (

Because plant cell walls vary in their polysaccharide compositions and lignin contents, their monosaccharide compositions and lignin contents are often determined, but these analyses are time consuming and laborious. We therefore investigated Fourier transform infrared (FTIR) spectroscopy coupled with partial least squares (PLS) regression analysis as a way of rapidly predicting the monosaccharide compositions and lignin contents of the cell walls of compression wood (CW) and opposite wood (OW) of the gymnosperm Pinus radiata. The effects were investigated of sample moisture content (ambient or dry) and sample particle size (large particles

Graphene has received significant attention in recent years due to its outstanding electronic, mechanical, chemical and physical properties. Graphene materials can potentially be used in a variety of applications, such as functional nanocomposites, electrodes, flexible transparent devices and thin conductive films. This article focuses on the analysis of structural evolution and development of different of reduced graphene oxides (rGOs), and the results are compared with structural features of functionalised reduced graphene oxide and graphene. The aromatic disorder and irregularity of these materials influence their own properties; particularly, their electrical conductivity aspects were studied indirectly through Raman spectroscopy. The quantification of their Raman spectra and microstructural analysis were examined to assess the relationship between aromatic structures and electrical conduction mechanism. The results showed that aromaticity of GO changes under different chemical reduction treatments and hydroiodic acid reduction gave an electrical conductivity of 103.3 S cm−1 as highest amongst a number of rGOs produced. Moreover, the integrity of aromatic structure through different reduced graphene oxides changed quite significantly and the Raman results were able to correlate the electrical conductivity with their structural regularity.

International audience; Tilted stems of softwoods form compression wood (CW) and opposite wood (OW) on their lower and upper sides, respectively. More is known about the most severe form of CW, severe CW (SCW), but mild CWs (MCWs) also occur widely. Two grades of MCWs, MCW1 and MCW2, as well as SCW and OW were identified in the stems of radiata pine (Pines radiata) that had been slightly tilted. The four wood types were identified by the distribution of lignin in the tracheid walls determined by fluorescence microscopy. A solution of the fluorescent dye acridine orange (AO) (0.02% at pH 6 or 7) was shown to meta chromatically stain the tracheid walls and can also be used to determine lignin distribution. The lignified walls fluoresced orange to yellow depending on the lignin concentration. Microscopically well characterized discs (0.5 mm diameter) of the wood types were used to determine lignin concentrations and lignin monomer compositions using the acetyl bromide method and thioacidolysis, respectively. Lignin concentration and the proportion of p-hydroxyphenyl units (H-units) relative to guaiacyl (G-units) increased with CW severity, with

Rapid, simple microchannel prototyping is critical for the development of modern microfluidic devices and platforms. Laser cutting (ablation) using a commercially available continuous wave (CW) CO2 laser followed by thermal bonding is one of the most common approaches for prototyping in thermoplastics such as polymethyl methacrylate (PMMA). However, this technique suffers from poorly controlled channel quality, inconsistent results from solvent-based post-processing, and inconsistency of thermal bonding. We have overcome these challenges through a systematic study of channel ablation in PMMA using a CW CO2 laser. A new solvent treatment approach results in clearly improved microchannel quality and processing consistency, with negligible residual solvent. Thermal bonding of the processed material showed fourfold increase in bonding strength with full retention of PMMA’s favourable optical clarity. As proof of concept, a high-quality three-layered microfluidic prototype is fabricated with this new method and its performance demonstrated.

Although a combined formulation of gum arabic and alginate is used for a variety of applications in pharmaceutical, food, and cosmetic industries, the origin of the interactions between these two polysaccharides has not yet been systematically studied or established. This study investigated the nature and strength of the possible interactions between gum arabic and alginate, using a variety of techniques: solid-state nuclear magnetic resonance spectroscopy (SS-NMR), infrared spectroscopy (FTIR), isothermal titration calorimetry (ITC), hydrophobic-interaction-chromatography (HIC), fluorescence spectroscopy, rheology, differential scanning calorimetry (DSC), and thermogravimetric (TG) analyses. The results showed that alginate interacts with gum arabic at pH 4, despite the net negative charge of each of them. Of the three main fractions of gum arabic (i.e., the arabinogalactan-peptide fraction containing 1 wt% protein, arabinogalactan protein containing 10 wt% protein, and glycoprotein containing 25–50 wt% protein), only the latter two fractions interact with alginate. The interaction intensity of glycoprotein with alginate was almost four times greater than the interaction intensity of arabinogalactan protein with alginate. We suggest the local positive charges in the proteinaceous content of gum arabic at pH 4 enables an electrostatic interaction between proteins in the second and the third fractions of gum arabic with negatively charged carboxylate groups in alginate. The gum arabic-alginate-mixture presented different thermal behavior, higher viscosity, and elastic modulus compared with the individual solutions of gum arabic or alginate at pH 4. The information obtained from this study will be beneficial for the rational design of biopolymers that give foods novel textural properties.

Polyaniline (PANI) and functionalised polyanilines (fPANI) are novel antimicrobial agents whose mechanism of action was investigated.Escherichia colisingle gene deletion mutants revealed that the antimicrobial mechanism of PANI likely involves production of hydrogen peroxide while homopolymer poly(3-aminobenzoic acid), P3ABA, used as an example of a fPANI, disrupts metabolic and respiratory machinery, by targeting ATP synthase and causes acid stress. PANI was more active againstE. coliin aerobic, compared to anaerobic, conditions, while this was apparent for P3ABA only in rich media. Greater activity in aerobic conditions suggests involvement of reactive oxygen species. P3ABA treatment causes an increase in intracellular free iron, which is linked to perturbation of metabolic enzymes and could promote reactive oxygen species production. Addition of exogenous catalase protectedE. colifrom PANI antimicrobial action; however, this was not apparent for P3ABA treated cells. The results presented suggest that PANI induces production of hydrogen peroxide, which can promote formation of hydroxyl radicals causing biomolecule damage and potentially cell death. P3ABA is thought to act as an uncoupler by targeting ATP synthase resulting in a futile cycle, which precipitates dysregulation of iron homeostasis, oxidative stress, acid stress, and potentially the fatal loss of proton motive force.

The dechlorination of chlorinated organic pollutants by zero valent iron (ZVI) is an important water treatment process with a complex dependence on many variables. This complexity means that there are reported inconsistencies in terms of dechlorination with ZVI and the effect of ZVI acid treatment, which are significant and are as yet unexplained. This study aims to decipher some of this complexity by combining Raman spectroscopy with gas chromatography-mass spectrometry (GC-MS) to investigate the influence of the mineralogy of the iron oxide phases on the surface of ZVI on the reductive dechlorination of pentachlorophenol (PCP). Two electrolytic iron samples (ZVI-T and ZVI-H) were found to have quite different PCP dechlorination reactivity in batch reactors under anoxic conditions. Raman analysis of the “as-received” ZVI-T indicated the iron was mainly covered with the ferrous oxide (FeO) wustite, which is non-conducting and led to a low rate of PCP dechlorination. In contrast, the dominant oxide on the “as-received” ZVI-H was magnetite which is conducting and, compared to ZVI-T, the ZVI-H rate of PCP dechlorination was four times faster. Treating the ZVI-H sample with 1 N H2SO4 made small change to the composition of the oxide layers and also minute change to the rate of PCP dechlorination. However, treating the ZVI-T sample with H2SO4 led to the loss of wustite so that magnetite became the dominant oxide and the rate of PCP dechlorination increased to that of the ZVI-H material. In conclusion, this study clearly shows that iron oxide mineralogy can be a contributing factor to apparent inconsistencies in the literature related to ZVI performance towards dechlorination and the effect of acid treatment on ZVI reactivity.

Point-of-care diagnostics are of interest in the medical, security and food industry, the latter particularly for screening food adulterated for economic gain. Milk adulteration continues to be a major problem worldwide and different methods to detect fraudulent additives have been investigated for over a century. Laboratory based methods are limited in their application to point-of-collection diagnosis and also require expensive instrumentation, chemicals and skilled technicians. This has encouraged exploration of spectroscopic methods as more rapid and inexpensive alternatives. Raman spectroscopy has excellent potential for screening of milk because of the rich complexity inherent in its signals. The rapid advances in photonic technologies and fabrication methods are enabling increasingly sensitive portable mini-Raman systems to be placed on the market that are both affordable and feasible for both point-of-care and point-of-collection applications. We have developed a powerful spectroscopic method for rapidly screening liquid milk for sucrose and four nitrogen-rich adulterants (dicyandiamide (DCD), ammonium sulphate, melamine, urea), using a combined system: a small, portable Raman spectrometer with focusing fibre optic probe and optimized reflective focusing wells, simply fabricated in aluminium. The reliable sample presentation of this system enabled high reproducibility of 8% RSD (residual standard deviation) within four minutes. Limit of detection intervals for PLS calibrations ranged between 140 - 520 ppm for the four N-rich compounds and between 0.7 - 3.6 % for sucrose. The portability of the system and reliability and reproducibility of this technique opens opportunities for general, reagentless adulteration screening of biological fluids as well as milk, at point-of-collection.

The implausible combination of centrifugal disc microfluidics and un-covered channels provides a simple way in which Raman spectroscopy can be implemented in industrially-relevant lab-on-a disc technology. Here we demonstrate these advantages by detecting very low concentrations of melamine in liquid milk, without pre-processing, without surface enhancement of the Raman signal and with no evidence of spectral contamination from the polymeric chip itself. A limit of detection (LOD) of 203 ppm for melamine in milk was achieved from Raman spectra of milk after drying. The centrifugal disc rotation and microchannel geometry results in rapid and reliable filling of the channels and in meniscus shape control, enabling reproducible Raman detection with quantitative precision.

Fluid inclusions provide a record of the physical and chemical composition of fluids that flow through the Earth's crust. Here, we describe a novel use of synchrotron Fourier Transform Infrared (FTIR) microscopy to map three parameters in individual fluid inclusions: (1) very low concentrations of CO 2 , (2) variations of the state of CO 2 and (3) variations in water structure. The intensity of the synchrotron light source allows compositional mapping of individual fluid inclusions, which provides high-resolution images of the distribution of different CO 2 and H 2 O species within individual inclusions. High resolution spectra of the CO 2 , recorded here for the first time in fluid inclusions, show the rotational lines of CO 2 gas. The results reveal predicted as well as unexpected distributions of CO 2 gas in the inclusions.

Agriculture, Domestic Production, and Site Function: Microfossil Analyses and Late Prehistoric Landscapes of the Society Islands. Pollen, phytolith, and starch analyses of sediment samples from the ‘Opunohu Valley, Mo‘orea, Society Islands were completed to retrieve data on prehistoric vegetation, Ma‘ohi planting practices, and cultigens. A second goal was to test whether microfossil data can aid in the identification of food production, storage, and plant processing locales at the local and community level, as modeled from ethnographic and ethnohistoric literature. In addition, we use Fourier Transform InfraRed spectroscopy (FTIR) on degraded and suspected starch, to provide another line of evidence for identifying starch grains. The ‘Opunohu Valley microfossil analyses provide direct evidence for 1) past environments and vegetation, including human–induced environmental change and pre–contact agricultural practices, as well as tentative evidence for 2) cultivation and plant processing, 3) domestic production and consumption, including cooking practices and surplus food storage, and 4) site function and specialization that are referenced in the ethnohistoric literature. Twenty economic taxa were identified in addition to grasses, sedges, and palms. Banana leaf phyotliths found in sub–surface pits in residential contexts provide supporting evidence that such features served for short–term food storage or breadfruit fermentation. In addition, we model the potential economic uses of Pandanus, Casuarina, Weinmannia, and paper mulberry based on microfossil data and ethnohistoric accounts. While microfossil studies are of clear interest for reconstructing landscapes, human–environmental interactions, and agricultural practices, they also have relevance to questions concerning socio–economic transformations at the local and community levels.

Effects of polarons on the single (NH4OH) and double (NH4OH þ LiOH) dedoped nanostructured products obtained in the oxidative polymerization of aniline are investigated. These effects are probed by 15 N and 13 C solid-state NMR, FTIR, Raman and EPR spectroscopy. The morphologies were imaged using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The micrographs confirmed the presence of mixed morphologies which include granular and nanotubular products. Single dedoping with NH4OH (SD) was not sufficient to completely remove positive charges. Subsequent dedoping with LiOH (DD) significantly removed positive charges. NMR experiments confirmed that the imine part of the structure has been more exposed to the effects of polarons. EPR data showed that the spin concentration in the DD samples was more than an order of magnitude lower that of the SD sample. The FTIR and Raman spectra exhibit characteristic bands for polyaniline and oligoanilines.

Described herein is a new printing method—direct writing of conducting polymers (CPs)— based on pipette-tip localized continuous electrochemical growth. A single barrel micropipette containing a metal wire (Pt) is filled with a mixture of monomer, supporting electrolyte, and an appropriate solvent. A droplet at the tip of the pipette contacts the substrate, which becomes the working electrode of a micro-electrochemical cell confined to the tip droplet and the pipette. The metallic wire in the pipette acts as both counter and reference electrode. Electropolymerization forms the CP on the working electrode in a pattern controlled by the movement of the pipette. In this study, various width poly(pyrrole) 2D and 3D structures are extruded and characterized in terms of microcyclic voltammetry, Raman spectroscopy, and scanning electron microscopy.

We demonstrate a simple route to versatile electrically addressable conductive polymer graft copolymer systems. The monomer of poly(3,4-ethylenedioxythiophene), one of the commercially most important conductive polymers, was modified by the addition of an ATRP-initiating site to grow brushes from. The modified monomer is easily accessible by a one-step synthesis from the commercially available 2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methanol. The modified monomer is subsequently electropolymerized onto large area gold-coated electrodes and utilized as a backbone for grafting pH-responsive poly(acrylic acid) brushes from.

We present the synthesis of a novel conducting polymer (CP) incorporating both pyrrole and thiophene units in its monomer, which is also substituted with an initiator for grafting of sidechains by atom-transfer radical polymerisation (ATRP). The precursor monomer for the CP macroinitiator, 2-(2,5-di(pyrrol-2-yl)thiophen-3-yl)ethyl 2-bromopropanoate) (PyThon) is very readily electropolymerised at low monomer concentrations and low applied potentials. Density functional theory (DFT) predictions of ionisation potentials and spin-charge distribution for PyThon are in good agreement with these experimental results. We present also the grafting of sidechains from electropolymerised PolyPyThon (PPyThon) to yield surface-confined polymer brushes. Functionalisation with polystyrene (PS), poly(2,3,4,5,6-pentafluorostyrene) (PFS) and poly(ethylene glycol) methyl ether acrylate (PEGMEA) is demonstrated and confirmed by FT-IR and water contact angle measurements. These PPyThon-based molecular brushes are electroactive in both water and acetonitrile, and show evidence of changes in surface conformation related to the redox state of the CP. The growth of human fibroblasts on PPyThon films is also demonstrated, indicating good biocompatibility of the polymer. We conceive PPyThon-based molecular brushes as a substrate for electrical stimuli-responsive surfaces with application particularly in the biomedical field.

Gallic acid was successfully incorporated into zein ultra-fine fibres at different loading amount (5%, 10% and 20%) in order to develop an encapsulating technology for functional ingredient delivery using electrospinning. The produced fibres exhibit diameters ranging from 327 to 387 nm. The physical and thermal properties of encapsulated gallic acid were determined by X-ray diffraction (XRD) and differential scanning calorimetry (DSC); and the interaction between gallic acid and zein was attested by attenuated total reflection-Fourier transform infrared (ATR-FTIR). Thermogravimetric analysis (TGA) demonstrated a different thermal stability of the fabricated complex before and after the gallic acid incorporation. Lastly, the 1,1′-diphenyl-2-picrylhydrazyl (DPPH) assay showed that the gallic acid had retained its antioxidant activity after incorporation in zein electrospun fibres. Overall, electrospinning technique had shown promising results as an efficient and effective method for the preparation of sub-micron structured encapsulated functional ingredient that may find uses in food industry.

A portable Raman system with an immersion fiber optic probe was assessed for point-of-collection screening for the presence of adulterants in liquid milk. N-rich adulterants and sucrose were measured in this proof-of-concept demonstration. Reproducibility, limit of detection range and other figures of merit such as specificity, sensitivity, ratio of predicted to standard deviation, standard error of prediction and root mean squared error for cross validation were determined from partial least squares (PLS) and partial least squares with discriminant analysis (PLS-DA) calibrations of milk mixtures containing 50–1000 ppm (parts per million) of melamine, ammonium sulphate, Dicyandiamide, urea and sucrose. The spectra were recorded by immersing the fiber optic probe directly in the milk solutions. Despite the high scattering background which was easily and reliably estimated and subtracted, the reproducibility for four N-rich compounds averaged to 11% residual standard deviation (RSD) and to 5% RSD for sucrose. PLS calibration models predicted the concentrations of separate validation sets with standard errors of prediction of between 44 and 76 ppm for the four N-rich compounds and 0.17% for sucrose. The sensitivity and specificity of the PLS-DA calibration were 92% and 89%, respectively. The study shows promise for use of portable mini Raman systems for routine rapid point-of-collection screening of liquid milk for the presence of adulterants, without the need for sample preparation or addition of chemicals.

We have developed a powerful general spectroscopic method for rapidly screening liquid milk for adulterants by combining reflective focusing wells simply fabricated in aluminum with a small, portable Raman spectrometer with a focusing fiber optic probe. Hemispherical aluminum sample wells were specially designed to optimize internal reflection and sampling volume by matching the focal length of the mirror to the depth of focus of the laser probe. The technique was tested on milk adulterated with 4 different nitrogen-rich compounds (melamine, urea, dicyandiamide, and ammonium sulfate) and sucrose. No sample preparation of the milk was needed, and the total analysis time was 4min. Reliable sample presentation enabled average reproducibility of 8% residual standard deviation. The limit of detection interval measured from partial least squares calibrations ranged between 140 and 520mg/L for the 4 N-rich compounds and between 7,000 and 36,000mg/L (0.7-3.6%) for sucrose. The portability of the system and the reliability and reproducibility of this technique open opportunities for general, reagentless screening of milk for adulterants at the point of collection.

The National Research Foundation under Grant number 2053306, The University of the Witwatersrand and the DST/NRF Centre of Excellence in Strong Materials.

Previous wetland vegetation records from Easter Island showing deforestation and Polynesian agriculture are limited to cores that rely on pollen, with a single cultigen pollen type identified: Urticaceae/Moraceae, possibly Broussonetia payrifera (paper mulberry). Here we redress this by also using phytolith and starch analyses on four lake sediment cores on a ~350-m transect along the southwest edge of Rano Kau, focusing on in-washed basal clayey layers. We also use a new method, Fourier transform infrared spectroscopy, to positively identify degraded starch collected from sedimentary deposits. The cores are the first samples recovered from an area in the lake that (a) lies below the relict village of Orongo, (b) is near a section of the crater believed to be most accessible from the Pacific coast, and (c) is far from the northern crater rim and receives high solar radiation, a likely benefit for crops of tropical origin. Pollen and phytoliths are abundant in the clayey layers and sparse in overlying layers of organic lake detritus and living rhizomes. Mixing of core deposits as a result of human activity has disordered the radiocarbon sequence, precluding development of an reliable chronology. Containing microfossils of several introduced cultigens, the clayey layers represent gardened terraces that have slumped into the lake. The data indicate large-scale deforestation and a mixed-crop production system including Broussonetia papyrifera, Colocasia esculenta (taro), Dioscorea alata (greater yam), Ipomoea batatas (sweet potato), Lagenaria siceraria (bottle gourd) and Musa (banana) sp. The data show (a) the potential for using the combined analyses to provide direct evidence of Polynesian horticulture on Easter Island and (b) that the island’s wetlands potentially hold extensive horticultural records. The study highlights the concept of ‘transported landscapes,’ whereby colonising people replace indigenous forests with artificial, imported agricultural landscapes.

The composition of the passive film formed on iron in 0.05 M NaOH was analyzed in situ with Raman microspectroscopy with preresonance enhancement during its growth by cyclic potentiodynamic polarization. The surface comprised more than one iron oxide and oxyhydroxide compound whose composition changed during the anodic and cathodic sweeps within successive cycles leading to film growth. The relative amounts of the different iron compounds in the film at selected potentials were determined from the spectra using multivariate curve resolution (MCR) with alternating least squares analysis. Individual spectra of six different such compounds, comprising Fe3O4 (magnetite), γ-Fe2O3 (maghemite), α-Fe2O3 (hematite), α-FeOOH (goethite), δ-FeOOH (feroxyhyte) and γ-FeOOH (lepidocrocite), were used as pure component spectra for the MCR optimization. The results obtained over the first 15 cycles indicate that α-FeOOH, γ-FeOOH, δ-FeOOH and γ-Fe2O3 were present in the film at the beginning of the passive region of the anodic polarization. The amount of water in the film was also observed to increase at this potential range. Further into the passive region (at more positive potentials), a decrease in the amount of water, which was accompanied by a decrease in α-FeOOH and γ-FeOOH in favor of an increase in the amount of γ-Fe2O3, was observed. Fe3O4 and α-Fe2O3 were not detected on the surface. With increasing number of cycles, the surface became increasingly amorphous or hydrated. Copyright © 2010 John Wiley & Sons, Ltd.

Raman spectroscopy, in principle, is an excellent technique for the study of molecular species developed on metal surfaces during electrochemical investigations. However, the use of the more common laser wavelengths such as the 514.5-nm line results in spectra of less than optimal intensity, particularly for iron oxide compounds. In the present work, near-resonance enhancement of the Raman spectra was investigated for the iron oxide and iron oxyhydroxide compounds previously reported to be present in the passive film on iron, using a tuneable dye laser producing excitation wavelengths between 560 and 637 nm. These compounds were hematite (α-Fe2O3), maghemite (γ-Fe2O3), magnetite (Fe3O4), goethite (α-FeOOH), akaganeite (β-FeOOH), lepidocrocite (γ-FeOOH) and feroxyhyte (δ-FeOOH). Optimum enhancement, when compared to that with the 514.5-nm line, was obtained for all the iron oxide and oxyhydroxide standard samples in the low wavenumber region (

Crystalline lithium metasilicate (Li2SiO3) nanoparticles have been synthesized using a sol–gel process with tetraethylorthosilicate and lithium ethoxide as precursors. The particle size examined by using transmission electron microscopy and BET-specific surface area techniques is in the range 5–50 nm, depending on the temperature at which the material is calcined. The crystalline Li2SiO3 forms at ambient temperature (∼40°C), and it remains in this phase after calcination at temperatures up to 850°C. The BET-specific surface area is ∼110 m2/g for material calcined at temperatures below 500°C, decreasing to ∼29 and ∼0.7 m2/g following calcination at 700° and 850°C, respectively. Solid-state 29Si NMR spectroscopy shows the presence of only Q2 structural units in the material. The lithium metasilicate is further characterized using differential scanning calorimetry and thermogravimetric analysis, and Fourier transform infrared spectroscopy.

Nanostructured gold substrates provide chemically stable, signal-enhancing substrates for the sensitive detection of a variety of compounds through surface-enhanced Raman spectroscopy (SERS). Recent developments in advanced fabrication methods have enabled the manufacture of SERS substrates with repeatable surface nanostructures that provide reproducible quantitative analysis, historically a weakness of the SERS technique. Here, we describe the novel use of gold-sputtered Blu-ray disc surfaces as SERS substrates. The unique surface features and composition of the Blu-ray disc recording surface lead to the formation of gold nano-islands and nanogaps following simple gold sputtering, without any background peaks from the substrate. The SERS performance of this substrate is strong and reproducible with an enhancement factor (EF) of 10(3) for melamine. A limit of detection (LOD) for this compound of 70 ppb and average reproducibility of ±12 % were achieved. Gold-sputtered Blu-ray discs thus offer an excellent alternative to more exotic gold SERS substrates prepared by advanced, time-consuming and expensive methods. Graphical abstract AFM 3D images of 1-μm(2) sections of uncoated and gold-sputtered recordable Blu-ray disc (BD-R) surfaces and the SERS signal obtained on the gold-sputtered surface for a 1000 ppm aqueous solution of melamine.

Adulteration of milk for commercial gain is acknowledged as a serious issue facing the dairy industry. Several analytical techniques can be used to detect adulteration but they often require time-consuming sample preparation, expensive laboratory equipment, and highly skilled personnel. Here we show that Raman spectroscopy provides a simple, selective, and sensitive method for screening milk, specifically for small nitrogen-rich compounds, such as melamine, urea, ammonium sulfate, dicyandiamide, and for sucrose. Univariate and multivariate statistical methods were used to determine limits of detection and quantification from Raman spectra of milk spiked with 50 to 1,000 mg/L of the N-rich compounds and 0.25 to 4% sucrose. Partial least squares (PLS) calibration provided limit of detection minimum thresholds

Surface Enhanced Raman spectroscopy (SERS) offers sensitive and non-invasive detection of a variety of compounds as well as unparalleled information for establishing the molecular identity of both inorganic and organic compounds, not only in biological fluids but in all other aqueous and non-aqueous media. The localized hotspots produced through SERS at the solution/nanostructure interface of clustered gold or silver nano-particles enables detection levels of parts per trillion. Recent developments in advanced fabrication methods have enabled the manufacture of SERS substrates with repeatable surface nanostructures which provide reproducible quantitative analysis, historically a weakness of the SERS technique. In this paper we describe the novel use of gold sputtered Blu-Ray surfaces as SERS substrates. Blu-Ray disks provide ideal surfaces of SERS substrates with their repeatable and regular nano-gratings. We show that the unique surface features and composition of the recording surface enables the formation of gold nano-islands with nanogaps, simply through gold sputtering, and relate this to a 600 fold signal increase of the melamine Raman signal in aqueous solutions and detection to 68 ppb. Melamine is a triazine compound and appears not only as environmental contaminant in environmental groundwater but also as an adulterant in foods due to its high nitrogen content. We have shown significant SERS signal enhancements for spectra of melamine using gold-sputtered Blu-Ray disk surfaces, with reproducibility of 12%. Blu-Ray disks have a unique combination of design, surface features and composition of the recording surface which makes them ideal for preparation of SERS substrates by gold sputter-coating.

Although three forms of lithium phosphate are known, a complete structural description of the highest temperature polymorph has not yet been given. In the present work, the phase transitions of lithium phosphate were investigated at high temperatures using Raman microscopy and x-ray powder diffraction. Both transitions were observed by following the temperature dependence of the totally symmetrical Raman stretching vibration of PO43−. Currently available structural information on the α form, resulting in P—O bond lengths of 1.787–1.899 A, as determined by valence bond calculations, are disputed here. A correlation between Raman wavenumber and bond length in inorganic phosphates estimates the P—O bond length in α-Li3PO4 to be around 1.57(1) A, which is in closer agreement with values for other orthophosphates of between 1.50 and 1.58 A. Copyright © 2002 John Wiley & Sons, Ltd.

Effects of heat treatment on structure and physicochemical properties of zein (Ze) and gallic acid loaded zein (Ze-GA) electrospun fiber mats were investigated. The electrospun fiber mats displayed different surface and physicochemical properties after being heat-cured at 150 °C for 24 h, which were closely related to the initial amount of loaded gallic acid. The gallic acid was released from the Ze-GA fiber mats in a constant manner, but heat curing decreased the rate of release. Heat curing remarkably increased the molecular weight of the Ze and Ze-GA electrospun fiber mats. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) analysis of the fiber mats indicated variations in zein protein secondary structure after heat curing. (13)C solid state NMR (SS-NMR) confirmed the presence of a different chemical environment among the fiber mats. The fabrication of heat-cured zein based electrospun fibers in this study may find applications in the food packaging industry.

Adsorption and oligomerization of H(4)SiO(4) at the amorphous TiO(2)-aqueous interface were studied using in situ Attenuated Total Reflectance Infrared (ATR-IR) and ex situ solid state (29)Si nuclear magnetic resonance (NMR). The ATR-IR spectra indicate that a monomeric silicate species is present at low silicate surface concentration (Γ(Si)). Above a threshold Γ(Si) linear silicate oligomers are formed and these oligomers dominate the surface at high Γ(Si). Interestingly the ATR-IR spectra of H(4)SiO(4) on the TiO(2) surface are very similar to those previously observed on the poorly ordered iron oxide phase ferrihydrite. The (29)Si NMR spectrum of silicate on the TiO(2) surface shows the presence of Si in three states with chemical shifts corresponding to isolated monomers (Q(0)), the ends of linear oligomers (Q(1)) and the middle of linear oligomers (Q(2)). The ratio of the area of the Q(1) and Q(2) peaks was ≈2:1 which is consistent with the proposed formation of linear silicate trimers by insertion of a solution H(4)SiO(4) between adjacent suitably orientated adsorbed silicate monomers. A structural interpretation indicates that the observed interfacial silicate oligomerization behavior is a general phenomenon whereby bidentate silicate monomers on oxide surfaces are disposed towards forming linear oligomers by condensation reactions involving their two terminal Si-OH groups. The high surface curvature of nanometer sized spheres inhibits the formation of interfacial silicates with a higher degree of polymerization.

Thin film porous silicon layers have been constructed in which the level of chemical modification to the pore walls is altered in a controlled gradient across the material. The gradient modification within such a nanoporous material represents a significant advance over gradients imposed across a flat surface. Gradients of methyl, pentyl acetate, and decyl groups are formed via electrochemical attachment of organohalides with an asymmetric electrode arrangement. The stability and hydrophobicity of the latter two systems have been improved through postprocess “end-capping” of the porous silicon with methyl groups. Two-dimensional mapping transmission FTIR microspectrophotometry and ATR-FTIR have been employed to characterize these new materials. Cleaving the surface-attached pentyl acetate groups to 5-hydroxypentyl groups leads to materials that can act as efficient visual indicators of the ethanol concentration in water over the range 1−10 vol %.