Sensory Perception of Non-Deuterated and Deuterated Organic Compounds

The chemical background of olfactory perception has been subject of intensive research, but no available model can fully explain the sense of smell. There are also inconsistent results on the role of the isotopology of molecules. In experiments with human subjects it was found that the isotope effect is weak with acetone and D₆-acetone. In contrast, clear differences were observed in the perception of octanoic acid and D₁₅-octanoic acid. Furthermore, a trained sniffer dog was initially able to distinguish between these isotopologues of octanoic acid. In chromatographic measurements, the respective deuterated molecule showed weaker interaction with a non-polar liquid phase. Quantum chemical calculations give evidence that deuterated octanoic acid binds more strongly to a model receptor than non-deuterated. In contrast, the binding of the non-deuterated molecule is stronger with acetone. The isotope effect is calculated in the framework of statistical mechanics. It results from a complicated interplay between various thermostatistical contributions to the non-covalent free binding energies and it turns out to be very molecule-specific. The vibrational terms including non-classical zero-point energies play about the same role as rotational/translational contributions and are larger than bond length effects for the differential isotope perception of odor for which general rules cannot be derived.     

Using Carrier Fringes to Study the High Temperature Deformation Behavior of a BGA Package Under Extended Dwell Times

There is a compelling need to experimentally understand solder joint deformation behavior at high temperatures over an extended period of time. Accordingly, the deformation behavior of solder joints in a Ceramic Ball Grid Array (CBGA) package mounted on an organic FR4 board under extended dwell time at a high temperature has been studied using laser moiré interferometry. The warpage and the in-plane horizontal deformation of the ceramic substrate and the organic board as a function of time were determined. The variation of the normal strains and shear strains in the solder joints with time were also investigated. It was found that increased sensitivity was necessary to accurately determine the strains in the small sized solder joints. A new method utilizing carrier fringes to increase the sensitivity of the moiré interferometry system is proposed and has been used to determine the strains in the small sized solder joints. Increased sensitivity can be obtained merely by changing the incident angle of the laser light on the surface of the specimen, thereby making it unnecessary to use expensive phase shifting apparatus with the traditional laser moiré system.     

A routine method for the determination of the TVOC content in wallcoverings using headspace gas-chromatography

A method for the fast routine analysis of the total content of volatile organic compounds in wallcoverings and paper products was developed, using headspace gas-chromatography for quantification. 57 wallcoverings of different types were investigated. Typical components were toluene, methyl-ethyl ketone, methyl-iso-butyl ketone, n-butyl acetate and iso-butyl acetate, all compounds being used as industrial solvents. The TVOC concentrations are calculated in toluene-carbon equivalents and ranged from 0.31 g/g to 1789 g/g with an average value of 123.22 g/g and a median of 20.37 g/g. To obtain an estimation of VOC-concentrations in indoor air, 10 selected wallcoverings were also analyzed in a 1 m³ climate test chamber. A correlation between headspace data and chamber concentrations could not be observed, which might be a result of increased analytical uncertainties at low emission rates under chamber conditions.     

Constancy maximization based weight optimization in high dimensional model representation

This work focuses on the weight function optimization in high dimensional model representation (HDMR) via constancy maximization. There are a lot of circumstances where HDMR’s weight function becomes completely flexible in its factors. The univariate coordinate changes which can be constructed to produce nonnegative factors in the integrands of HDMR component, are perhaps the most important ones of these cases. Here, the weight function is considered as the square of a linear combination of certain basis functions spanning an appropriately chosen Hilbert space. Then, the coefficients of these linear combinations are determined to maximize the HDMR’s constant term contribution to the function. Although the resulting equations are nonlinear we could have been able to approximate the solutions by using recently proven fluctuationlessness theorem on matrix representations appearing in the equations.     

Analysis of odour compounds from scented consumer products using gas chromatography-mass spectrometry and gas chromatography-olfactometry

Scented consumer products are being bought in increasing amounts and gaining more popularity. There is, however, relatively little information available about their ingredients, emissions and allergenic potential. Frequently, a mixture of different fragrance substances and not solely an individual substance contributes to the overall desired smell. The aim of this study was to investigate the odorous volatile organic compounds (OVOCs) in consumer products containing fragrances. Over 44 products were selected: various scented candles, printing products with different scent types and other products types particularly meant to be used indoors. Measurements were carried out in a desiccator. Air samples were collected on thermal desorption tubes to determine the released fragrance substances by means of gas chromatography-mass spectrometry (GC-MS). Moreover, gas chromatography-olfactometry (GC-O) was used to obtain sensory data and to ensure no important odorant was overlooked. Using both methods it was possible to distinguish between odour active and inactive compounds and subsequently to identify almost 300 different odorants across all scented products. Besides the advantage of differentiation, as the human nose is a very sensitive detector, GC-O was found to be a useful tool for detecting traces and chosen target compounds. One focus in this study lay on the 26 EU-regulated fragrance allergens to prove their relevance in scented consumer goods. In total, 18 of them were identified, with at least one substance being present in almost every product. Benzyl alcohol, cinnamaldehyde, citronellol, eugenol, linalool and limonene were the prevalently detected allergens. Particularly linalool and limonene were observed in over 50% of the products. In addition, eugenol appeared to be one of the most frequently detected compounds in trace-level concentrations in the candle emissions.     

Fluctuation free multivariate integration based logarithmic HDMR in multivariate function representation

This paper focuses on the Logarithmic High Dimensional Model Representation (Logarithmic HDMR) method which is a divide–and–conquer algorithm developed for multivariate function representation in terms of less-variate functions to reduce both the mathematical and the computational complexities. The main purpose of this work is to bypass the evaluation of N–tuple integrations appearing in Logarithmic HDMR by using the features of a new theorem named as Fluctuationlessness Approximation Theorem. This theorem can be used to evaluate the complicated integral structures of any scientific problem whose values can not be easily obtained analytically and it brings an approximation to the values of these integrals with the help of the matrix representation of functions. The Fluctuation Free Multivariate Integration Based Logarithmic HDMR method gives us the ability of reducing the complexity of the scientific problems of chemistry, physics, mathematics and engineering. A number of numerical implementations are also given at the end of the paper to show the performance of this new method.     

Bound Analysis Through HDMR for Multivariate Data Modelling - CMMSE

Multivariate data modelling problems consist of a number of nodes with associated function (class) values. The main purpose of these problems is to construct an analytical model to represent the characteristics of the problem under consideration. Because the devices, tools, and/or algorithms used to collect the data may have incapabilities or limited capabilities, the data set is likely to contain unavoidable errors. That is, each component of data is reliable only within an interval which contains the data value. To this end, when an analytical structure is needed for the given data, a band structure should be determined instead of a unique structure. As the multivariance of the given data set increases, divide–and–conquer methods become important in multivariate modelling problems. HDMR based methods allow us to partition the given multivariate data into less variate data sets to reduce the complexity of the given problem. This paper focuses on Interval Factorized HDMR method developed to determine an approximate band structure for a given multivariate data modelling problem having uncertainties on its nodes and function values.     

Determination of VOC and TVOC in Air Using Thermal Desorption GC-MS – Practical Implications for Test Chamber Experiments

The determination of volatile organic compounds (VOC) species and concentrations are important for the evaluation of indoor air quality. Numerous methods exist for the determination of levels of both VOC and TVOC (total volatile organic compounds). These include the use of direct-reading instruments as well as gas chromatographic techniques. The benefits and drawbacks of the various methods are well known, and none provide precise measurement of the complex VOC mixtures that constitute TVOC in indoor air. A specific approach for TVOC measurement has been proposed in Europe in ECA-report no.19 to overcome these shortcomings. On this basis a practical analytical method was developed and applied to emission test chamber studies. Special focus was required on compounds of high volatility and the preparation of calibration standards.     

Sensitive determination of airborne diisocyanates by HPLC: 4,4′-Diphenylmethane-diisocyanate (MDI)

An HPLC/fluorescence method is described, which enables the sensitive determination of airborne monomeric 4,4′-diphenyl-methane-diisocyanate (MDI). A glass fiber filter coated with 1 mg 1-(2-pyridyl)-piperazine (2PP) is used for sampling. The urea derivative MDI-2PP, which shows a high molecular absorption coefficient and exhibits a sufficient fluorescence response, is extracted from the filter by use of a 90:10 acetonitrile/DMSO mixture. Linear calibration curves were obtained for the indoor range (7.8 ng/mL to 74.7 ng/mL) and the workplace range (27.7 ng/mL to 676.0 ng/mL). A detection limit of 9.0 ng/m³ can be achieved on a total sampling volume of 1000 L. The method is easy to handle and therefore highly suitable for a routine determination of MDI in the atmosphere of workplace areas and living environments. Received: 17 December 1997 / Revised: 2 March 1998 / Accepted: 4 March 1998