Gas chromatography of monosaccharides as O-isopropylidene derivatives. Analysis of hay,grass silage,and alkali-treated barley straw after mild and strong acid hydrolysis

Samples of hay, silage, untreated and ammonia-or alkali-treated barley straw were subjected to mild and strong acid hydrolysis, and the liberated monosaccharides were analysed by gas-liquid chromatography as their O-isopropylidene derivatives. From the mild acid hydrolysis, the total fructose content of the material and the amount of easily hydrolysed glucose were determined, allowing the content of non-structural carbohydrates to be estimated. In the same operation, the content of mannitol and arabinotol in the feed samples can be determined. From the strong acid hydrolysis, the total amounts of each aldose in the forage materials were determined.     

Models of complex human screening and correcting of social data

National statistical agencies annually spend great budgets in the continuous collection of a huge amount of data on individual persons, households, business activities, etc., to serve the information needs of a number of national and international government and private users. Substantial parts of their budgets are consumed in checking and improving the quality of the data collected. Because of their complexities, these tasks have depended on the handling of specialists. To save both processing time and resources and to improve the processing involved in solving and servicing data requests, these tasks have high priority. The present paper outlines research carried out in Norway on using the neural network paradigm to improve the data quality checking and improvement in large-scale data masses.     

Cell-membrane damage and element leaching in transplanted Parmelia sulcata lichen related to ambient SO2, temperature, and precipitation

Measurements were performed in lichen (Parmelia sulcata) transplants, to gain insight into the lichen vitality as possibly affected by both element deposition or lichen element content and further ambient atmospheric conditions (temperature, precipitation, SO2 levels). The electrical conductivity of rinsing solutions was used to assess cell-membrane damage in Parmelia sulcata in an experiment, which ran from August 2001 until August 2002. Element contents of the solutions and lichens were determined by inductively coupled plasma-optical emission spectrometry and by k0-instrumental neutron activation analysis, respectively. Factor analysis (MCATTFA) was used to determine grouping of elements of similar origin and/ or behavior. All in all, the data indicate that, apartfrom lichen Na and Cl levels, and for temperature and precipitation, no clear relationships with conductivity could be observed. Conductivity was mostly related to released Na, Cl, K, Mg, and Cs. On the basis of concentrations, Na, Cl, and K could be considered as largely determining the conductivity. The data suggest a different origin for K than that for Na and Cl: the latter two are most probably due to effects from sea salt sprays. Parmelia sulcata was sensitive enough to reflect appreciable ambient rises in air SO2 and resistant enough to recover afterward. MCATTFA on selected elements (K, Sc, Cu, V, As, and Sb) indicated the absence of any comparability between K and V, As and Sb, suggesting differences in origin and/or chemico-physical occurrence. Generally speaking, the present data suggest that the comparability of lichen vitality in large geographical areas may be limited and governed by the area's variability in temperature and precipitation rather than by variability in metal deposition rates. The leaching data on all elements and element groups, however, strongly suggest that wet deposition may also severely affect lichen elemental levels. This latter observation means that comparing outcomes for time or spatial series of lichen samples should be accompanied by a comparably careful monitoring of (preceding) ambient conditions.     

A new phase diagram for layered antiferromagnetic films

Magnetic multilayer films provide convenient model systems for studying the physics of antiferromagnetic films and surfaces. Here we report on the magnetic reversal and domain structure in antiferromagnetically coupled Co/Pt multilayers that are isomorphic to layered antiferromagnetic films with perpendicular magnetic anisotropy. We observe two distinct remanent states and reversal modes of the system. In mode 1 the magnetization in each layer reverses independently, producing an antiferromagnetic remanent state that shows full lateral correlation and vertical anticorrelation across the interlayers. In mode 2 the reversal in adjacent layers is locally synchronized with a remanent state that is vertically correlated but laterally anticorrelated in ferromagnetic stripe domains. Theoretical energy calculations of the two ground states identify a new phase boundary that is in good agreement with our experimental results.     

Three-phase mixed-wet capillary pressure curves from a bundle of triangular tubes model

We present a bundle of triangular tubes model that simulates three-phase mixed-wet capillary pressure curves for any sequences of gas, oil, and water invasion processes. A diversity of cross-sectional fluid configurations may occur because of pore shape and different combinations of the contact angles. We use expressions for the capillary entry pressures that truly accounts for the mixed wettability condition and the possibility of simultaneous displacement of the fluids occupying the cross-sections. As a consequence, invasion does not necessarily proceed in the order of monotonic increasing or decreasing pore size. We simulate primary drainage and imbibition first. The saturation dependencies of the three-phase capillary pressures are analyzed for the subsequent gas injections and waterfloods and compared with the results from a similar bundle of cylindrical tubes model. Simulations are performed for three sets of contact angles representing oil-wet conditions with variable contact angle hysteresis. It is shown that the capillary pressure at the end of primary drainage, P_cow^max, strongly affects the saturation dependencies in the bundle of triangular tubes. For moderate values of P_cow^max, we have identified regions in the saturation space where two or all three capillary pressures are functions of two saturations, while the corresponding results from the bundle of cylindrical tubes often show that only one of the capillary pressures depends on more than one saturation, regardless of P_cow^max. The differences are caused by the capillary entry pressures in the triangular tubes that are strongly affected by the hinging interfaces in the corners when contact angle hysteresis is assumed. This leads to different bulk pore occupancies in the two bundle models, and hence different saturation dependencies. Furthermore, the level of gas–water and oil–water capillary pressure is higher for the bundle of triangular tubes during the gas and water invasion processes. The saturation dependencies, capillary levels and pore occupancies calculated from triangular tubes approach the corresponding results calculated from cylindrical tubes when P_cow^max is increased.     

Photoacoustic and photothermal spectroscopy — novel tools for the analysis of particulate matter

Measurments on powders using photoacoustic (PAS) and photothermal (PTS) spectroscopic techniques are described. These methods avail themselves of the heat that is generated in a sample upon irradiation, which can be used to analyse and identify the sample through its absorption spectrum.Three different techniques have been used to extract the required information: (i) By having the specimen inside a chamber, illuminating it through a window and recording the resulting pressure variations; (ii) similarly, only having the sample outside the chamber but in contact with a membrane in the chamber wall: (iii) by measuring the extra thermal emission from the object when heated upon illumination. The advantages of using PAS and PTS methods to powder analysis are presented, and their applications to in-stream measurements of particulate solid properties are discussed.     

Effects of molecular weight and elastic segment flexibility on syneresis in Ca-alginate gels

Syneresis in Ca-alginate gels was studied as a function of the alginate molecular weight and the degree of flexibility of the elastic segments. Small angle X-ray scattering of alginate gels reveals an increased lateral association of junction zones when entering a Ca²⁺ regime giving syneresis. This suggests growth of junction zones to be the primary driving force for syneresis. Ca-alginate gels prepared from alginates with different molecular weights show a reduced syneresis with decreasing M_w. A reduced syneresis is also observed when fractions of a high M_w alginate is replaced by short alginate molecules enriched in guluronate residues. The effect of altering the monomer sequence of the elastic segments spanning the junction zones was studied by converting poly-mannuronate regions to alternating guluronate/mannuronate sequences by the mannuronan C5-epimerase AlgE4. This epimerisation reaction gives a more flexible elastic segment. The epimerased alginates yielded gels with larger syneresis compared to the non-epimerased, native alginate samples. Thus, both molecular weight and elastic segment flexibility are needed in a molecular model for describing syneretic behaviour in alginate gels. These parameters will to a large extent determine to which degree the non-equilibrium nature of the alginate gel is macroscopically expressed (syneresis).     

Measurement of the Oxygen Transmission Rate of Co‐extruded Wine Bottle Closures Using a Luminescence‐Based Technique

The oxygen transmission rate (OTR) is a value commonly measured in different industries to evaluate oxygen flow through all types of packaging. The Mocon^® Ox‐tran^® method (Mocon Inc., Minneapolis, MN, USA) for measuring OTR is globally accepted and is recommended in different standards such as the ASTM (F1307‐02), but in practice, only a limited number of samples can be analysed, and the stabilisation of the measurement takes time. In this paper, a simple, non‐destructive technique allowing measurement of co‐extruded closure OTR is presented. The established protocol allows measurement of oxygen ingress through the closures or at the interface between closures and bottleneck and avoids possible leakages that can happen when bottlenecks are glued onto metallic plates. Oxygen permeating in the bottle is measured by a luminescence‐based technology using separate sensors supplied by PreSens^® (Precision Sensing GmbH, Regensburg, Germany). The simple set‐up and the use of a non‐destructive luminescence‐based technology make this an easy test to perform. Moreover, the development of a predictive model allows us to reduce the analysis time to one week. Comparison with the well‐established Mocon Ox‐tran method shows good accordance between the two techniques. This new method allows the measurement of more samples in less time without compromising analytical performance. This method could become a useful quality control procedure in the wine industry to assess OTR performances of closures. Copyright © 2011 John Wiley & Sons, Ltd.