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Process applications of mid-infrared (MIR) spectrometry may involve replacement of the spectrometer and/or measurement probe, which generally requires a calibration transfer method to maintain the accuracy of analysis. In this study, direct standardisation (DS), piecewise direct standardisation (PDS) and spectral space transformation (SST) were compared for analysis of ternary mixtures of acetone, ethanol and ethyl acetate. Three calibration transfer examples were considered: changing the spectrometer, multiplexing two probes to a spectrometer, and changing the diameter of the attenuated total reflectance (ATR) probe (as might be required when scaling up from lab to process analysis). In each case, DS, PDS and SST improved the accuracy of prediction for the test samples, analysed on a secondary spectrometer-probe combination, using a calibration model developed on the primary system. When the probe diameter was changed, a scaling step was incorporated into SST to compensate for the change in absorbance caused by the difference in ATR crystal size. SST had some advantages over DS and PDS: DS was sensitive to the choice of standardisation samples, and PDS required optimisation of the window size parameter (which also required an extra standardisation sample). SST only required a single parameter to be chosen: the number of principal components, which can be set equal to the number of standardisation samples when a low number of standards (n < 7) are used, which is preferred to minimise the time required to transfer the calibration model.

Some types of textile fibres are considered to be the cause of allergic reactions and other adverse health effects on humans. The main compounds behind these health problems usually contain azo groups in their chemical structure, which are widely employed as azo dyes in the manufacture of textile and clothing products. In this respect, availability of simple analytical procedures for identifying azo groups in textiles is of concern, not only for toxicological studies, but also for clinical and forensic investigations. In this work, conventional Raman spectrometry was assessed as an analytical tool for identification of the azo function in the extracts of fibres obtained after applying a liquid-solvent extraction procedure to the polyester-based textile products. A medium-polarity solvent of ethanol-diethyl ether (1:1 mixture) was shown to be the most effective extraction medium. Two laser lines at 514.5 nm and 785 nm were compared, with the longer wavelength preferred as additional peaks were identified in the Raman spectrum, which had better signal-to-background and signal-to-noise ratios owing to decreased fluorescence in contrast to excitation at 514.5 nm. The method reported is a convenient procedure that can be applied in many instances when rapid screening of fibre dyes is required.

A novel two-step sequential extraction has been developed to assess the bioaccessibility of As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn in airborne particulate matter following inhalation and transport into the human gastrointestinal tract by mucociliary clearance. A new artificial mucus fluid (AMF) was used to determine the bioaccessible potentially toxic element (PTE) fraction in the upper airways, in sequence with the simplified bioaccessibility extraction test (SBET) or the stomach phase of the unified bioaccessibility method (gastric fluid only) (UBMG). Filter dynamic measurement system TX40 filters smeared with soil reference material (BGS RM 102) were used as test samples. Analysis was performed by ICP-MS. Comparison between results obtained for soil alone and when the soil was supported on TX40 filters indicated that the presence of the substrate did not affect the extraction efficiency, although a large Zn blank was detected. The sequential AMF→SBET extraction liberated similar amounts of Fe, Mn, Ni and Zn to the SBET alone; but significantly less Cd; and significantly more As, Cr, Cu and Pb. The sequential AMF→UBMG extraction liberated similar amounts of Cd, Cr, Mn and Zn to the UBMG alone, but significantly less As, Fe and Ni; and significantly more Cu and Pb. Enhanced extractability was due to the greater quantities of exchangeable ions and complexing agents present. Adoption of a two-step sequential extraction (AMF followed by either the SBET or the UBMG) is recommended because it is more representative of biological conditions and avoids overestimation or underestimation of bioaccessible PTE concentrations. Graphical Abstract Simulated PM10 sample: BGS RM 102 ironstone soil on TX40 filter.

Summary Background We previously reported the 5-year results of the phase 3 IBCSG 23-01 trial comparing disease-free survival in patients with breast cancer with one or more micrometastatic (≤2 mm) sentinel nodes randomly assigned to either axillary dissection or no axillary dissection. The results showed no difference in disease-free survival between the groups and showed non-inferiority of no axillary dissection relative to axillary dissection. The current analysis presents the results of the study after a median follow-up of 9·7 years (IQR 7·8–12·7). Methods In this multicentre, randomised, controlled, open-label, non-inferiority, phase 3 trial, participants were recruited from 27 hospitals and cancer centres in nine countries. Eligible women could be of any age with clinical, mammographic, ultrasonographic, or pathological diagnosis of breast cancer with largest lesion diameter of 5 cm or smaller, and one or more metastatic sentinel nodes, all of which were 2 mm or smaller and with no extracapsular extension. Patients were randomly assigned (1:1) before surgery (mastectomy or breast-conserving surgery) to no axillary dissection or axillary dissection using permuted blocks generated by a web-based congruence algorithm, with stratification by centre and menopausal status. The protocol-specified primary endpoint was disease-free survival, analysed in the intention-to-treat population (as randomly assigned). Safety was assessed in all randomly assigned patients who received their allocated treatment (as treated). We did a one-sided test for non-inferiority of no axillary dissection by comparing the observed hazard ratios (HRs) for disease-free survival with a margin of 1·25. This 10-year follow-up analysis was not prespecified in the trial's protocol and thus was not adjusted for multiple, sequential testing. This trial is registered with ClinicalTrials.gov, number NCT00072293. Findings Between April 1, 2001, and Feb 8, 2010, 6681 patients were screened and 934 randomly assigned to no axillary dissection (n=469) or axillary dissection (n=465). Three patients were ineligible and were excluded from the trial after randomisation. Disease-free survival at 10 years was 76·8% (95% CI 72·5–81·0) in the no axillary dissection group, compared with 74·9% (70·5–79·3) in the axillary dissection group (HR 0·85, 95% CI 0·65–1·11; log-rank p=0·24; p=0·0024 for non-inferiority). Long-term surgical complications included lymphoedema of any grade in 16 (4%) of 453 patients in the no axillary dissection group and 60 (13%) of 447 in the axillary dissection group, sensory neuropathy of any grade in 57 (13%) in the no axillary dissection group versus 85 (19%) in the axillary dissection group, and motor neuropathy of any grade (14 [3%] in the no axillary dissection group vs 40 [9%] in the axillary dissection group). One serious adverse event (postoperative infection and inflamed axilla requiring hospital admission) was attributed to axillary dissection; the event resolved without sequelae. Interpretation The findings of the IBCSG 23-01 trial after a median follow-up of 9·7 years (IQR 7·8–12·7) corroborate those obtained at 5 years and are consistent with those of the 10-year follow-up analysis of the Z0011 trial. Together, these findings support the current practice of not doing an axillary dissection when the tumour burden in the sentinel nodes is minimal or moderate in patients with early breast cancer. Funding International Breast Cancer Study Group.

We describe a new, simple apparatus that permits accurate measurement of reactive organic carbon vapor pressure from heavy crude oils when used with a gas chro-matograph. The apparatus is analogous to the Reid vapor pressure apparatus that is used for vapor pressure measurement of light hydrocarbons. This system overcomes many of the shortcomings experienced when the Reid method is applied to heavy crudes. We explain the operation of the system and present results from measurement of heavy crudes from Southern California. Measurements on oil samples collected from storage tanks agreed well with analysis of headspace gases in the tanks.

Our retrospective review of prospectively collected data evaluated the efficacy of minimally invasive parathyroidectomy (MIP) and compared preoperative imaging modalities in a rural referral centre.Patients with a diagnosis of primary hyperparathyroidism underwent surgeon-performed ultrasound (SUS) and technetium-99 m sestamibi (MIBI). Radiologist-performed ultrasound (RUS) was sought when the diagnosis remained in doubt. Four-dimensional computed tomography (4DCT) first replaced RUS in mid-2014, then MIBI as a frontline modality in 2015. MIP was conducted if possible and bilateral neck exploration (BNE) when localization remained doubtful. Treatment was evaluated by histopathology and serum parathyroid hormone and calcium levels at 6 weeks.A total of 122 of 165 (73.9%) glands were removed by MIP and 43 of 165 (26.1%) by BNE. Of 15 cases with non-localizing preoperative investigations, one patient had a negative BNE. A total of 160 of 165 (97.0%) patients underwent a successful operation, with five (3.0%) suffering persistent post-operative hypercalcaemia. SUS had a sensitivity of 79.4% (131/165) and a positive predictive value (PPV) of 97.0% (131/135). MIBI had a sensitivity of 60.0% (81/135) and a PPV of 95.3% (81/85). RUS produced a sensitivity of 65.5% (76/116) and PPV of 98.7% (76/77). When used as a second-line modality, 4DCT had a sensitivity of 76.9% (10/13) and PPV of 100%. The sensitivity and PPV were 85.7% (18/21) and 94.7% (18/19) after 4DCT's promotion to first-line use.MIP can be safely performed in rural centres of adequate volume. We recommend that operations be guided by SUS with routine use of an adjunctive modality. Our study has seen 4DCT replace MIBI in this regard.

Atmospheric pollution plays important roles in the weathering of the historical buildings and glass windows. Samples of white powdered weathering products, recovered during restoration of the stained-glass windows of Leon Cathedral in Spain, were characterised using a combination of scanning electron microscopy (SEM) with energy dispersive-X ray spectrometry (ED-XRS), Fourier transform-infrared (FT-IR) spectroscopy and Raman spectrometry. The presence of sulphates, and to a lesser extent carbonates, in the white powdered product is clear indication of the participation of atmospheric acidifying gases, particularly SO x , in the weathering process. It is interesting to note that there was no indication of the participation of NO x gases. There was, however, evidence that the putty and mortar used to seal/join the glasses were major sources of the weathering products. In this way, this study suggests sealants more resistant to oxidation, such as silicone- and zirconia-based materials, should be considered for repairing glass windows in historic buildings to avoid exacerbating degradation.

A specially designed thermal vaporiser was used with a process mass spectrometer designed for gas analysis to monitor the esterification of butan-1-ol and acetic anhydride. The reaction was conducted at two scales: in a 150 mL flask and a 1L jacketed batch reactor, with liquid delivery flow rates to the vaporiser of 0.1 and 1.0 mLmin(-1), respectively. Mass spectrometry measurements were made at selected ion masses, and classical least squares multivariate linear regression was used to produce concentration profiles for the reactants, products and catalyst. The extent of reaction was obtained from the butyl acetate profile and found to be 83% and 76% at 40°C and 20°C, respectively, at the 1L scale. Reactions in the 1L reactor were also monitored by in-line mid-infrared (MIR) spectrometry; off-line gas chromatography (GC) was used as a reference technique when building partial least squares (PLS) multivariate calibration models for prediction of butyl acetate concentrations from the MIR spectra. In validation experiments, good agreement was achieved between the concentration of butyl acetate obtained from in-line MIR spectra and off-line GC. In the initial few minutes of the reaction the profiles for butyl acetate derived from on-line direct liquid sampling mass spectrometry (DLSMS) differed from those of in-line MIR spectrometry owing to the 2 min transfer time between the reactor and mass spectrometer. As the reaction proceeded, however, the difference between the concentration profiles became less noticeable. DLSMS had advantages over in-line MIR spectrometry as it was easier to generate concentration profiles for all the components in the reaction. Also, it was possible to detect the presence of a simulated impurity of ethanol (at levels of 2.6 and 9.1% mol/mol) in butan-1-ol, and the resulting production of ethyl acetate, by DLSMS, but not by in-line MIR spectrometry.

A thermal vaporiser has been designed for analysis of liquid streams by a process mass spectrometer normally used for gas analysis. Concentrations of benzene, toluene and o-xylene at mg kg−1 levels in ethanol were determined from continuous vaporisation of the liquid. Ions with m/z values of 39, 57, 73, 77, 78, 91, 92 and 106 were selected and the optimal regression model (multiple linear regression with mean-centring) was found using an automated design of experiments approach to calibration model selection. It was discovered that the linearity of the response allowed excellent calibration to be performed using only four standards (at 0 and 110 mg kg−1 for each of the three analytes) and that there were minimal inter-analyte interferences. The detection limit of benzene, toluene and o-xylene was 0.5, 0.8 and 0.5 mg kg−1, respectively. Average differences between the actual and predicted concentrations, expressed as a percentage of the actual concentrations, for 27–82 mg kg−1 of benzene, toluene and o-xylene were 0.5–1.4%, 0.0–0.4% and 0.3–1.6%, respectively, while the average relative standard deviations were 1.3–2.6%, 1.0–2.5% and 1.1–2.3%, respectively. Detection of 3 mg kg−1 changes in the concentration of each of the analytes (at the 36 mg kg−1 level) was also demonstrated, indicating the sensitivity of the technique and the potential ability of the procedure to detect minor deviations in the specification of process streams from continuous analysis.

Coal fly ash is a waste by-product of the coal fire industry, which generates many environmental problems. Alternative uses of this material would provide efficient solutions for this by-product. In this work, nitric acid-etched coal fly ash labelled with 2-mercaptoethanol or thioglycolic acid was assessed for retention of Al(III), As(III), Cu(II), Cd(II), Fe(III), Mn(II), Hg(II), Ni(II), Pb(II) and Zn(II) ions. The bonding characteristics between the organic compounds with the solid support, as well as with the metal ions, were evaluated using various surface analytical techniques. Visualization of the organically-functionalized coal fly ash particle was possible using scanning electron microscopy (SEM), while the elemental composition of the functionalized material, before and after retention of the metal ions, was obtained by energy dispersive (ED)-X ray spectrometry (XRS) and electrothermal atomic absorption spectrometry (ETAAS). Fourier transform infrared (FT-IR) spectrometry and Raman spectrometry were used to obtain information about the functional groups. It was found that some metal(oid) ions (As, Ni, Pb, Zn) were coordinated through the mercaptan group, while other metal(oid)s (Al, Cd, Cu, Fe, Hg, Mn) were apparently bonded to oxygen atoms. A low-cost and effective solid phase retention system for extraction of heavy metals from aqueous solutions was thus developed.

Summary Background For patients with breast cancer and metastases in the sentinel nodes, axillary dissection has been standard treatment. However, for patients with limited sentinel-node involvement, axillary dissection might be overtreatment. We designed IBCSG trial 23–01 to determine whether no axillary dissection was non-inferior to axillary dissection in patients with one or more micrometastatic (≤2 mm) sentinel nodes and tumour of maximum 5 cm. Methods In this multicentre, randomised, non-inferiority, phase 3 trial, patients were eligible if they had clinically non-palpable axillary lymph node(s) and a primary tumour of 5 cm or less and who, after sentinel-node biopsy, had one or more micrometastatic (≤2 mm) sentinel lymph nodes with no extracapsular extension. Patients were randomly assigned (in a 1:1 ratio) to either undergo axillary dissection or not to undergo axillary dissection. Randomisation was stratified by centre and menopausal status. Treatment assignment was not masked. The primary endpoint was disease-free survival. Non-inferiority was defined as a hazard ratio (HR) of less than 1·25 for no axillary dissection versus axillary dissection. The analysis was by intention to treat. Per protocol, disease and survival information continues to be collected yearly. This trial is registered with ClinicalTrials.gov, NCT00072293. Findings Between April 1, 2001, and Feb 28, 2010, 465 patients were randomly assigned to axillary dissection and 469 to no axillary dissection. After the exclusion of three patients, 464 patients were in the axillary dissection group and 467 patients were in the no axillary dissection group. After a median follow-up of 5·0 (IQR 3·6–7·3) years, we recorded 69 disease-free survival events in the axillary dissection group and 55 events in the no axillary dissection group. Breast-cancer-related events were recorded in 48 patients in the axillary dissection group and 47 in the no axillary dissection group (ten local recurrences in the axillary dissection group and eight in the no axillary dissection group; three and nine contralateral breast cancers; one and five regional recurrences; and 34 and 25 distant relapses). Other non-breast cancer events were recorded in 21 patients in the axillary dissection group and eight in the no axillary dissection group (20 and six second non-breast malignancies; and one and two deaths not due to a cancer event). 5-year disease-free survival was 87·8% (95% CI 84·4–91·2) in the group without axillary dissection and 84·4% (80·7–88·1) in the group with axillary dissection (log-rank p=0·16; HR for no axillary dissection vs axillary dissection was 0·78, 95% CI 0·55–1·11, non-inferiority p=0·0042). Patients with reported long-term surgical events (grade 3–4) included one sensory neuropathy (grade 3), three lymphoedema (two grade 3 and one grade 4), and three motor neuropathy (grade 3), all in the group that underwent axillary dissection, and one grade 3 motor neuropathy in the group without axillary dissection. One serious adverse event was reported, a postoperative infection in the axilla in the group with axillary dissection. Interpretation Axillary dissection could be avoided in patients with early breast cancer and limited sentinel-node involvement, thus eliminating complications of axillary surgery with no adverse effect on survival. Funding None.

Laboratory experiments and modeling analysis have been conducted to gain insight on the self-excited unstable flame behaviors of a model gas turbine combustor that utilizes a low-swirl injector (LSI). The combustor consists of a 5.7 cm I.D. LSI firing into 18 cm diameter by 32 cm or 20.3 cm long cylindrical enclosures at atmospheric condition. The experiments involved lean premixed turbulent CH4 (0.6

Cellulose acetate artefacts from various museums have been analysed by micro-FTIR spectrometry and ion chromatography in an attempt to identify whether there are any common factors associated with their degradation. There was good correlation between the IR spectra, the concentration of ions extracted from an artefact and the visual degree of degradation. Deacetylation, which produced acetate, was found to be the primary process with chain scission (indicated by the appearance of oxalate ion) occurring after degradation is well advanced. Oxidative degradation (indicated by formate) was not a major factor for most artefacts studied, however the loss of formate by volatilization cannot be excluded. Changes to the polymer matrix as a consequence of degradation were indicated in some artefacts by the presence of plasticiser on the surface and increased levels of extractable chloride and/or sulphate. A simple test of the onset of degradation was developed that involved analysis of an aqueous swab of the surface of an artefact by ion chromatography. Analysis by X-ray fluorescence spectrometry allowed identification of selenium as a potential stabilizing element in certain areas of a doll which were less degraded than other parts that had no selenium.

The effects of hydrogen on the dynamic response of self-excited oscillations in a model low-swirl injector (LSI) gas turbine combustor have been studied by high-speed imaging of flame light emissions and OH ∗ chemiluminescence on two thermoacoustically coupled unsteady flames burning CH 4 (113 kW) and a fuel blend of 0.9H 2 /0.1CH 4 (74 kW). The two flames have different shapes. The CH 4 flame is lifted and bowl-shaped and the 0.9H 2 /0.1CH4 flame is attached and M-shaped. From phase-resolved PIV, the dominant unsteady flow structures of both flames are ring vortices shed from the LSI exit rim. The vortices of the CH 4 flame burn intermittently and those in the 0.9H 2 /0.1CH 4 flame burn consistently. Proper orthogonal decomposition analysis of OH ∗ and calculation of Rayleigh indices show different flame structures are responsible for generating flame oscillations and acoustic coupling. CH 4 flame oscillations are associated with flame folding near the standing ring vortex below the trailing edge of the lifted flame, intermittent burning of the shear layer, and irregular acoustic driving. The 0.9H 2 /0.1CH 4 flame has regular and stronger forcing. A key contributor to the 0.9H 2 /0.1CH 4 flame driving is merging of the central flat flame with the reacting rolled-up vortices, resulting in an instantaneous narrow band of localized high heat release density that is in phase with the pressure oscillation. Cyclic variations in the flow of the reactants also contribute to non-linear effects. High reactivity of H 2 generates a situation where the geometry of the attached shear layer flame and central disk-shaped flame creates a very favorable situation for exciting higher-pressure oscillations at a lower total heat release than CH 4 flames. To control combustion oscillations in a fuel-flexible LSI gas turbine combustor, the mitigation of flame attachment and/or formation of the outer shear layer would be necessary.

The simplified bioaccessibility extraction test (SBET) and the stomach phase of the unified bioaccessibility method (UBM) have been modified for use in assessing the bioaccessibility of potentially toxic elements in samples of PM10 collected during routine air quality monitoring. Arsenic, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn were measured by inductively coupled plasma mass spectrometry in extracts of synthetic PM samples prepared by loading candidate soil reference material BGS102 onto TX40 (Teflon-coated borosilicate) filters widely used in standard commercial tapered element oscillating microbalance/filter dynamics measurement system (FDMS) ambient particulate monitors. Analysis of blanks revealed two important sources of contamination that had to be controlled in order to achieve reproducible results. The syringe filters used in the SBET released Cu and Zn into sample extracts during filtration and had to be washed with 80 mL of 0.4 M glycine at pH 1.5 immediately prior to use, whilst the FDMS filters used to collect PM10 were found to contain sufficient extractable Zn (ca. 3 μg per filter) to almost double the concentration released by the soil. The latter is a consequence of the use of Zn in filter manufacture and so could not be eliminated, but was successfully overcome by means of blank-subtraction. A ten-fold miniaturisation of the SBET and six-fold miniaturisation of the UBM allowed 0.1 g samples to be processed, with analyte recoveries generally within ±10% of those obtained when the conventional procedures were used. Comparison between results obtained when the modified procedures were applied to soil alone, and when soil was loaded onto FDMS filters, indicated that the presence of the filter had no effect on extraction efficiency, except for Fe, provided blank-correction was performed. Results obtained for As, Cd and Pb when the modified UBM was applied to BGS102 on FDMS filters were 4.40 ± 0.04, 0.224 ± 0.002 and 17.3 ± 0.8 mg kg−1, respectively (n = 3), all within recommended ranges.

A total of 383 tablets of a pharmaceutical product were analyzed by backscatter and transmission Raman spectrometry to determine the concentration of an active pharmaceutical ingredient (API), chlorpheniramine maleate, at the 2% m/m (4 mg) level. As the exact composition of the tablets was unknown, external calibration samples were prepared from chlorpheniramine maleate and microcrystalline cellulose (Avicel) of different particle size. The API peak at 1594 cm(-1) in the second derivative Raman spectra was used to generate linear calibration models. The API concentration predicted using backscatter Raman measurements was relatively insensitive to the particle size of Avicel. With transmission, however, particle size effects were greater and accurate prediction of the API content was only possible when the photon propagation properties of the calibration and sample tablets were matched. Good agreement was obtained with HPLC analysis when matched calibration tablets were used for both modes. When the calibration and sample tablets are not chemically matched, spectral normalization based on calculation of relative intensities cannot be used to reduce the effects of differences in physical properties. The main conclusion is that although better for whole tablet analysis, transmission Raman is more sensitive to differences in the photon propagation properties of the calibration and sample tablets.

Particle size distribution and compactness have significant confounding effects on Raman signals of powder mixtures, which cannot be effectively modeled or corrected by traditional multivariate linear calibration methods such as partial least-squares (PLS), and therefore greatly deteriorate the predictive abilities of Raman calibration models for powder mixtures. The ability to obtain directly quantitative information from Raman signals of powder mixtures with varying particle size distribution and compactness is, therefore, of considerable interest. In this study, an advanced quantitative Raman calibration model was developed to explicitly account for the confounding effects of particle size distribution and compactness on Raman signals of powder mixtures. Under the theoretical guidance of the proposed Raman calibration model, an advanced dual calibration strategy was adopted to separate the Raman contributions caused by the changes in mass fractions of the constituents in powder mixtures from those induced by the variations in the physical properties of samples, and hence achieve accurate quantitative determination for powder mixture samples. The proposed Raman calibration model was applied to the quantitative analysis of backscatter Raman measurements of a proof-of-concept model system of powder mixtures consisting of barium nitrate and potassium chromate. The average relative prediction error of prediction obtained by the proposed Raman calibration model was less than one-third of the corresponding value of the best performing PLS model for mass fractions of barium nitrate in powder mixtures with variations in particle size distribution, as well as compactness.

Cellulose nitrate is susceptible to hydrolysis as well as loss of plasticiser when left in a humid atmosphere. A comparison of the ageing behaviour of cellulose nitrate samples prepared from cotton linters was used to simulate the artefacts studied in a previous study. Certain artefacts were also subjected to accelerated ageing at 12%, 55% and 75% relative humidity at 70 °C. The rate of degradation was observed to vary with the RH, indicating the connection between the absorption of moisture and the hydrolysis process. The effect of varying the sulphate level on the rate of hydrolysis was studied using concentrations similar to those detected in artefacts. The study was carried out using

Recently, transmission Raman spectroscopy has been shown to be a valuable tool in the volumetric quantification of pharmaceutical formulations. In this work a Monte Carlo simulation and experimental study are performed to elucidate the dependence of the Raman signal on depth from the viewpoint of probing pharmaceutical tablets and powders in this experimental configuration. The transmission Raman signal is shown to exhibit a moderate bias toward the center of the tablets and this can be considerably reduced by using a recently developed Raman signal-enhancing concept, the "photon diode." The enhancing element not only reduces the bias but also increases the overall Raman signal intensity and consequently improves the signal-to-noise ratio of the measured spectrum. Overall, its implementation with appropriately chosen reflectivity results in a more uniform volumetric sampling across the half of the tablet where the photon diode is used (or across the tablet's entire depth if two photon diodes are used on each side of tablet) and enhanced overall sensitivity. These findings are substantiated experimentally on a segmented tablet by inserting a poly(ethelyne terephthalate) (PET) film doped with TiO(2) at different depths and monitoring its contribution to the overall transmission Raman signal from the segmented tablet. The numerical simulations also indicate considerable sensitivity of the overall Raman signal to the absorption of the sample, which is in line with large migration distances traversed by photons in these measurements. The presence of sample absorption was shown numerically to reduce the signal enhancement effect while the overall depth-dependence profile remained broadly unchanged. The absorption was also shown to produce a depth profile with the photon diode similar to that without it, although with a reduced absolute intensity of Raman signals and diminished enhancement effect.

Cellulose nitrate was one of the first semi-synthetic plastics to be commercially exploited and as such many museums contain a large number of artefacts illustrating the versatility of this plastic for the creation of a wide variety of functional and aesthetic artefacts. Conservators find themselves faced with the challenge of preserving these ageing artefacts which are showing evidence of significant degradation. The challenge is enhanced by artefacts of similar age and type exhibiting different degrees of degradation. This paper reports the analytical study of selected historical artefacts to explore the origins of these differences. A connection between the durability of the artefacts and the quality of the original synthetic process is identified, indicating the influence of inherent chemical factors on stability. The major contributory factors determining degradation appear to be the sulphate content remaining from the stabilization process and the rate of loss of the camphor plasticizer. A simple swab test is proposed to aid the identification of artefacts which are potentially susceptible to degradation. The test involves analysis of swab extracts by ion chromatography to reveal the presence of oxalate, which is indicative of cellulose nitrate chain scission.

Large-scale commercial bioprocesses that manufacture biopharmaceutical products such as monoclonal antibodies generally involve multiple bioreactors operated in parallel. Spectra recorded during in situ monitoring of multiple bioreactors by multiplexed fiber-optic spectroscopies contain not only spectral information of the chemical constituents but also contributions resulting from differences in the optical properties of the probes. Spectra with variations induced by probe differences cannot be efficiently modeled by the commonly used multivariate linear calibration models or effectively removed by popular empirical preprocessing methods. In this study, for the first time, a calibration model is proposed for the analysis of complex spectral data sets arising from multiplexed probes. In the proposed calibration model, the spectral variations introduced by probe differences are explicitly modeled by introducing a multiplicative parameter for each optical probe, and then their detrimental effects are effectively mitigated through a "dual calibration" strategy. The performance of the proposed multiplex calibration model has been tested on two multiplexed spectral data sets (i.e., MIR data of ternary mixtures and NIR data of bioprocesses). Experimental results suggest that the proposed calibration model can effectively mitigate the detrimental effects of probe differences and hence provide much more accurate predictions than commonly used multivariate linear calibration models (such as PLS) with and without empirical data preprocessing methods such as orthogonal signal correction, standard normal variate, or multiplicative signal correction.

A novel method has been devised to derive kinetic information about reactions in microfluidic systems. Advantages have been demonstrated over conventional procedures for a Knoevenagel condensation reaction in terms of the time required to obtain the data (fivefold reduction) and the efficient use of reagents (tenfold reduction). The procedure is based on a step change from a low (e.g., 0.6 μL min(-1)) to a high (e.g., 14 μL min(-1)) flow rate and real-time noninvasive Raman measurements at the end of the flow line, which allows location-specific information to be obtained without the need to move the measurement probe along the microreactor channel. To validate the method, values of the effective reaction order n were obtained employing two different experimental methodologies. Using these values of n, rate constants k were calculated and compared. The values of k derived from the proposed method at 10 and 40 °C were 0.0356 ± 0.0008 mol(-0.3) dm(0.9) s(-1) (n = 1.3) and 0.24 ± 0.018 mol(-0.1) dm(0.3) s(-1) (n = 1.1), respectively, whereas the values obtained using a more laborious conventional methodology were 0.0335 ± 0.0032 mol(-0.4) dm(1.2) s(-1) (n = 1.4) at 10 °C and 0.244 ± 0.032 mol(-0.3) dm(0.9) s(-1) (n = 1.3) at 40 °C. The new approach is not limited to analysis by Raman spectrometry and can be used with different techniques that can be incorporated into the end of the flow path to provide rapid measurements.

Motor vehicle emissions of ammonia have been measured at a California highway tunnel in the San Francisco Bay area. Between 1999 and 2006, light-duty vehicle ammonia emissions decreased by 38 ± 6%, from 640 ± 40 to 400 ± 20 mg kg −1 . High time resolution measurements of ammonia made in summer 2001 at the same location indicate a minimum in ammonia emissions correlated with slower-speed driving conditions. Variations in ammonia emission rates track changes in carbon monoxide more closely than changes in nitrogen oxides, especially during later evening hours when traffic speeds are highest. Analysis of remote sensing data of Burgard et al. (Environmental Science Technology 2006, 40, 7018–22) indicates relationships between ammonia and vehicle model year, nitrogen oxides, and carbon monoxide. Ammonia emission rates from diesel trucks were difficult to measure in the tunnel setting due to the large contribution to ammonia concentrations in a mixed-traffic bore that were assigned to light-duty vehicle emissions. Nevertheless, it is clear that heavy-duty diesel trucks are a minor source of ammonia emissions compared to light-duty gasoline vehicles.

Electrothermal atomization of beryllium from graphite and tungsten surfaces was compared with and without the use of various chemical modifiers. Tungsten proved to be the best substrate, giving the more sensitive integrated atomic absorption signals of beryllium. Tungsten platform atomization with zirconium as a chemical modifier was used for the determination of beryllium in several NIST SRM certified reference samples, with good agreement obtained between the results found and the certified values. The precision of the measurements (at 10 microgL(-1)), the limit of detection (3sigma), and the characteristic mass of beryllium were 2.50%, 0.009 microgL(-1) and 0.42 pg, respectively.

For safety, economic efficiency and environmental efficiency understanding and predicting the behaviour of a chemical reaction are of greatest importance in industry. Hard-modelling, the evolution of a chemical reaction by the rate law derived from the molecular mechanism, is a powerful method for this application. Any change in the experimental equipment or conditions does not have an impact on the model and does not require time consuming recalibration or reanalysis. Thus, hard-modelling is suitable for extrapolations of the reaction dynamics to other concentrations and/or temperatures. In this context, the solvent-free esterification of 1-butanol (BuOH) by acetic anhydride (AA) using 1,1,3,3-tetramethylguanidine (TMG) as a base catalyst, to form butyl acetate (BuOA) and acetic acid (AH) has been analysed, in a comparative study, in three different reactors (located in different laboratories) of different volumetric scales (50, 75 mL and 5 L) by mid-IR (50 mL) or near-IR (75 mL and 5 L) spectroscopy. Chemical suppliers and experimenters were also different but the same experimental design (temperatures and initial concentrations) was applied to all measurements. Multivariate kinetic hard-modelling of the spectroscopic signals was applied to the kinetic data sets corresponding to each reactor. The importance of finding the simplest model that sufficiently describes the experimental data is discussed. Compared to previously published results, a non-contradictory but simplified and consistent kinetic model (first order in AA, BuOH and TMG) was found to be optimal to fit the data from all three reactors taken within a temperature range from 30 to 50 °C. The corresponding model parameters, rate constant kref,1 (at reference temperature Tref) and activation energy Ea,1 define a mean-centred Arrhenius equation and were in reasonable agreement considering the different experimental environment, spectroscopic methods, volumetric scales and relatively scarce factorial design of experiments employed; the latter being responsible for a limited definition of Ea,1. For validation of the mechanism, pure component mid-IR spectra have been interpreted and assigned in terms of their characteristic bands

International audience; There is an increasing interest in using Raman spectroscopy to identify polymorphic forms and monitor phase changes in pharmaceutical products for quality control. Compared with other analytical techniques for the identification of polymorphs such as X-ray powder diffractometry and infrared spectroscopy, FT-Raman spectroscopy has the advantages of enabling fast, in situ, and nondestructive measurements of complex systems such as suspension samples. However, for suspension samples, Raman intensities depend on the analyte concentrations as well as the particle size, overall solid content, and homogeneity of the solid phase in the mixtures, which makes quantitative Raman analysis rather difficult. In this contribution, an advanced model has been derived to explicitly account for the confounding effects of a sample's physical properties on Raman intensities. On the basis of this model, a unique calibration strategy called multiplicative effects correction (MEC) was proposed to separate the Raman contributions due to changes in analyte concentration from those caused by the multiplicative confounding effects of the sample's physical properties. MEC has been applied to predict the anhydrate concentrations from in situ FT-Raman measurements made during the crystallization and phase transition processes of citric acid in water. The experimental results show that MEC can effectively correct for the confounding effects of the particle size and overall solid content of the solid phase on Raman intensities and, therefore, provide much more accurate in situ quantitative predictions of anhydrate concentration during crystallization and phase transition processes than traditional PLS calibration methods.

Laboratory experiments have been conducted to investigate the fuel effects on the turbulent premixed flames produced by a gas turbine low-swirl injector (LSI). The lean-blow off limits and flame emissions for seven diluted and undiluted hydrocarbon and hydrogen fuels show that the LSI is capable of supporting stable flames that emit x (@ 15% O 2 ). Analysis of the velocity statistics shows that the non-reacting and reacting flowfields of the LSI exhibit similarity features. The turbulent flame speeds, S T , for the hydrocarbon fuels are consistent with those of methane/air flames and correlate linearly with turbulence intensity. The similarity feature and linear S T correlation provide further support of an analytical model that explains why the LSI flame position does not change with flow velocity. The results also show that the LSI does not need to undergo significant alteration to operate with the hydrocarbon fuels but needs further studies for adaptation to burn diluted H 2 fuels.

Broadband acoustic emission signals were obtained by attaching a piezoelectric transducer, sensitive up to 750 kHz, to the external wall of a 1 L jacketed glass reactor. Measurements were acquired of itaconic acid particles mixing in toluene; the total area of the acoustic emission signal from 55-500 kHz increased when the particle concentration, particle size or stir rate were increased. Signals at frequencies above 200 kHz were less sensitive to changes in particle size than those at lower frequencies. From calculation of the area of the signal in the range 55-200 kHz as a percentage of the signal area over the range 55-500 kHz, for mixtures of different size ranges of itaconic acid, it was possible to obtain an estimate of the mean particle size of a mixture. The heterogeneous esterification reaction of itaconic acid and 1-butanol was monitored non-invasively. A decrease in the overall acoustic signal area between 60 and 500 kHz was observed as the reaction progressed. Particle size and concentration information were contained in the amplitude of the acoustic emission signal, while the emission frequency yielded information on changes in the mean particle size.

The widespread occurrence of thecotrichite, Ca3(CH3COO)3Cl(NO3)2·7H2O, in the museum environment is explained theoretically by construction and examination of its phase diagram. Thecotrichite formation was simulated in the laboratory to identify the key factors involved in its production. This efflorescence occurs on porous limestone or calcareous artefacts such as pottery, stored in wooden cabinets that generate acetic acid vapour. Salt production depends on the moisture content of the object and the concentration of acetic acid in its surroundings. Furthermore, for thecotrichite to form the artefact must contain soluble chloride and nitrate salts.

Condensed phase zirconium species, produced over the temperature range 200–2500 °C, were analysed using scanning electron microscopy (SEM), energy dispersive (ED) X-ray spectrometry, attenuated total reflectance (ATR) Fourier transform infrared (FT-IR) spectrometry and Raman spectrometry. Very similar results were derived using pyrolytic and non-pyrolytic graphite platforms. Zirconia or zirconia mixed together with alumina in a solid solution were the predominant species on the platform surface up to about 1500 °C. The presence of alumina prevents conversion of the tetragonal phase of zirconia to the monoclinic phase, which is dominant for zirconia alone. Above 1500 °C, aluminium and zirconium follow independent thermochemical transformations; reduction of zirconia and alumina by graphite occurs, but aluminium species are volatilised, whereas some Zr metal remains on the surface after a full heating cycle at 2500 °C, provided that 100 μg of Zr is initially deposited on the platform. There was no evidence that zirconium carbide is formed to any significant extent and so chemical modification by Zr in ETAAS seems to involve the effects of zirconia or Zr metal on the analyte.

A new approach for low emission gas turbines was investigated by modifying a typical production high-swirl injector (HSI) for gas turbine combustors to operate in a novel low-swirl mode (LSI). This LSI (S = 0.5) was configured in the laboratory and investigated by particle image velocimetry at firing rates of 9–87 kW (1

Development of managers is key to the future health of hospitality and tourism: sectors increasingly affected by trends in globalisation and pressures on competitiveness. Reporting on a round table event, driving forces affecting the development of the sectors are identified; major stakeholder views are offered and the ensuing discussion of graduate profiles was organised into three main scenarios: professional developers, portfolio strategists and pragmatic mavericks. The scenarios identify varying approaches for graduates, higher education institutions and employers. One outcome of the analysis is to note high levels of interdependency between these stakeholders in ensuring any desired outcomes and argues for long‐term, strategic co‐operation.

The identification and distribution of condensed phase species produced on a graphite platform at temperatures between 200 and 2000 °C was studied using data obtained by scanning electron microscopy (SEM), energy dispersive (ED) X-ray spectrometry and Raman microanalysis. The first general conclusion is that there is no unique path in the thermal transformation of the metal chlorides tested, even for a particular metal chloride. Sodium, potassium and calcium chlorides showed similar vaporization characteristics, evolving mainly as monochlorides, while magnesium, beryllium and aluminium mainly vaporized as free atoms, following transformation caused by hydrolysis. The replacement of chlorine atoms by oxygen occurred at lower temperatures for beryllium and aluminium chlorides than for magnesium chloride. There were some particular areas on the platform surface where other mechanisms, such as hydrolysis of calcium chloride and dissociation of sodium chloride in the condensed phase, seemed occasionally to occur to a minor extent.

Thermal processes are important in areas ranging from biological to advanced materials processing. Here, we present a method for measuring temperature profiles in three dimensions using a combination of two-photon microscopy and calibrated temperature-dependent fluorescent dyes, or 'molecular thermometers'. We have found that the dye, tris(2,2'-bipyridine)ruthenium(II) ( ) possesses both a strong temperature dependence in the range 0–60°C and a large cross section for two-photon induced fluorescence, making it ideal for two-photon thermal imaging. The technique is used to map out the temperature profile in a thick polyacrylate film containing an embedded wire heater, and, from that, the thermal properties of the polymer are determined.

Thermal treatment of alkaline and alkaline earth metal sulphates on a graphite platform was performed over the temperature range 200–2000 °C. The solid residues produced at each temperature were located by scanning electron microscopy (SEM) and then identified by energy-dispersive (ED) X-ray spectroscopy and Raman microanalysis. Additional experiments involved the dissolution of the residues from the platform and analysis by ion chromatography to determine the concentration of sulphate and other ions. A decomposition pattern was derived for the alkaline and alkaline earth metal sulphates. The transformation of the metal sulphates was dependent on temperature and the cation present. In general, the metal sulphates do not undergo significant decomposition to other species at temperatures less than 900 °C, with the exception of magnesium and beryllium sulphates, which are transformed into metal oxides to some extent. Above 900 °C, major transformations occur mainly for sodium, magnesium, and beryllium sulphates. For all the salts studied, there is evidence of the formation of species such as metal sulphides and elemental sulphur.

This work is concerned with an investigation into the practicalities of using ICP-MS data obtained from the analysis of ecstasy tablets to provide linkage information from seizure to seizure. The generated data was analysed using different statistical techniques, namely principal component analysis, Hierarchical clustering and artificial neural networks. The relative merits of these different techniques are discussed.

Recent studies associate particulate air pollution with adverse health effects; however, the exposure to indoor particles of outdoor origin is not well characterized, particularly for individual chemical species. In response to this, a field study in an unoccupied, single-story residence in Clovis, California has been conducted. Real-time particle monitors were used both outdoors and indoors to quantify PM2.5 nitrate, sulfate, and carbon. The results show that reduced indoor sulfate and carbon levels are primarily due to deposition and penetration losses. However, measured indoor ammonium nitrate levels were often observed to be at significantly lower levels than expected based solely on penetration and deposition losses. The additional reduction appears to be due to the transformation of ammonium nitrate into ammonia and nitric acid indoors, which are subsequently lost by deposition and sorption to indoor surfaces. The size of the effect is dependent upon factors such as temperature, relative humidity, and ventilation rate.

Methods have been developed and compared for the analysis of a glycerol-based polyether polyol using a low-field, medium-resolution NMR spectrometer, with an operating frequency of 29 MHz for 1 H . Signal areas in the time and frequency domains were used to calculate the ethylene oxide (EO) content of individual samples. The time domain signals (free induction decay) were analysed using a new version of the direct exponential curve resolution algorithm (FID-DECRA). Direct analysis of the 1 H NMR FT spectra gave percentage EO concentrations of reasonable accuracy (average percentage error of 1.3%) and precision (average RSD of 1.8%) when compared with results derived from high-field 13 C NMR spectrometry. The direct FID-DECRA method showed a negative bias (−0.8±0.12% w/w) in the estimation of percentage EO concentration, but the precision (average RSD of 0.9%) was twice as good as that of direct spectral analysis. When the 13 C NMR analysis was used as a reference method for univariate calibration of the 1 H NMR procedures, the best accuracy (average percentage error of 0.5%) and precision (average RSD of 0.6%) were obtained using FID-DECRA, for EO concentrations in the range 14.8–15.5% w/w. An additional advantage of FID-DECRA is that the analytical procedure could be automated, which is particularly desirable for process analysis.

A method of variable selection for use with orthogonally designed calibration data sets, such as factorial or partial factorial designs, is described. The procedure works by assessing the degree of correlation between each X variable (e.g., wavelength) and each Y variable (concentration, composition, etc.). The X variables are then ranked according to the degree of correlation. A forward selection method is then used to determine the optimum number of high-ranked variables to be used for calibration purposes. The algorithm was tested on a data set obtained by near infrared (NIR) spectrometry. Significant improvements in the prediction accuracy of partial least-squares (PLS) models were observed for two of the components in the chemical mixture by using the selected wavelengths in the NIR spectra rather than all the variables in the original spectra or the variables obtained using a spectral-variance-based variable selection method.

In-line Raman, near infrared and UV-visible spectometries, and at-line low-field NMR spectrometry have been used to monitor the acid-catalysed esterification of crotonic acid and butan-2-ol. Repeat reactions were carried out in a 1 L batch reactor. Spectra taken during the reactions, along with reference ester concentrations determined by gas chromatography (GC), were used to determine the concentration of 2-butyl crotonate as the reaction proceeded. Ester concentrations were determined from 1st derivative Raman and UV-visible spectra by employing univariate calibration models, whereas the low-field NMR and NIR data required multivariate analysis by partial least squares regression. The techniques have been compared on the basis of the accuracy and between-run precision of the 2-butyl crotonate concentrations, and the ability to determine the rate constant of the reaction in the shortest possible time after the start of the reaction. The ester concentrations determined by all of the techniques were similar to those obtained by the GC reference method. In-line UV-visible spectrometry gave the poorest between-run precision. Raman and NIR spectrometries provided an estimate of the rate constant of the reaction after 90 min when the ester concentration had reached 0.09 mol dm−3, meaning that if the rate constant at this time was not as expected then corrective action could be taken to salvage the batch.

A low-field medium-resolution NMR spectrometer, with an operating frequency of 29 MHz for 1H, has been developed for use in process analysis. The information that is attainable at this field strength has been investigated with the use of samples from a wide range of applications including the qualitative monitoring of a benzene production process, the estimation of the average ethoxy chain length in nonyl phenol ethoxylates, and the determination of strong acid concentrations. At low field, the spectra of multi-component samples often exhibit overlapping peaks, so multivariate calibration methods are necessary for quantitative analysis. Simulated data have been used to illustrate the effects of signal-to-noise ratio (SNR), resolution, and line shape on the predictive ability of partial least-squares (PLS) calibration routines, with SNR shown to have a greater impact than resolution on accuracy and precision. PLS calibration models were applied successfully in the analysis of samples from a methacrylamide process and a simulated esterification reaction. The accuracy (1–5% w/w.

A novel strategy for building and maintaining calibration models has been developed for use when the future boundaries of the sample set are unknown or likely to change. Such a strategy could have an impact on the economics and time required to obtain and maintain a calibration model for routine analysis. The strategy is based on both principal component analysis (PCA) and partial least squares (PLS) multivariate techniques. The principal action of the strategy is to define how “similar” a new sample is to the samples currently defining the calibration dataset. This step is performed by residuals analysis, following PCA. If the new sample is considered to have a spectrum “similar” to previously available spectra, then the model is assumed able to predict the analyte concentration. Conversely, if the new sample is considered “dissimilar”, then there is new information in this sample, which is unknown to the calibration model and the new sample is added automatically to the calibration set in order to improve the model. The strategy has been applied to a real industrial dataset provided by BP Amoco Chemicals. The data consists of spectra of 102 sequential samples of a raw material. The strategy produced an accurate calibration model for both target components starting with only the first four samples, and required a further 17 reference measurements to maintain the model for the whole sampling sequence, which was over a 1-year period.

A combustion concept to achieve ultralow emissions (NOx 2 ppm and CO 20 ppm) was tested on a 18 kW low-swirl burner (LSB). It is based on lean premixed combustion combined with flue gas recirculation (FGR) and partially reformed natural gas (PRNG). Flame stability and emissions were assessed as a function of , FGR, and PRNG. The results show that PRNG improves flame stability and reduces CO, with no impact on NOx at 0.8. A one-dimensional flame simulation satisfactorily predicted prompt NOx under lean conditions with high FGR. Two catalysts were tested in a prototype steam reformer, and the results were used to estimate reactor volume and steam requirements in a practical system. An advanced Sud Chemie catalyst displayed good conversion efficiency at relatively low temperatures and high space velocities, which indicates that the reformer can be small and will track load changes. Tests conducted on the LSB with FGR and 0.05 PRNG show that boilers using a LSB with PRNG and high FGR and close to stoichiometry can operate with low emissions and high efficiency.

Transmission near-infrared (NIR) measurements of a 1 mm thick aspirin disk were made at different positions as it was moved through a stack of eight 0.5 mm thick disks of microcrystalline cellulose (Avicel). The magnitude of the first derivative of absorbance for the aspirin interlayer at 8934 cm−1 was lower when the disk was placed at the top or bottom of the stack of Avicel disks, with the largest signal observed when the aspirin was positioned at the central positions. The variation in signal with depth is consistent with that observed previously for transmission Raman spectrometry. In both cases, the trend observed can be attributed to lower photon density at the air-sample interface, relative to the center of the sample, owing to loss of photons to the air. This results in a reduction in the number of photons absorbed or Raman photons generated and subsequently detected when the interlayer occupies a near-surface position.