Direct computation of critical equilibrium states for spatial beams and frames

In this paper, explicit formulas for second order derivatives of the residual vector with respect to the state variables for a geometrically exact 3D beam element based on the Reissner's model are presented. These derivatives are required when a direct non‐linear stability eigenvalue problem is solved by the Newton's method. If the external load is parametrized by a single parameter, such an eigenvalue problem consists of solving the critical state variables, the eigenmode, and the critical load parameter from the equation system consisting of the equilibrium equations, the criticality condition, and some auxiliary conditions depending on the type of a critical point. Copyright ©2011 John Wiley & Sons, Ltd.     

Regioisomeric structure determination of alpha- and gamma-linolenoyldilinoleoylglycerol in blackcurrant seed oil by silver ion high-performance liquid chromatography and mass spectrometry

Gamma-linolenic acid (Gla) and oils containing Gla have evident positive effects on a variety of disorders, and therefore, the structure of triacylglycerols (TAGs) containing Gla is of special interest. The regioisomeric structures of TAGs 18:3(n-3)/18:2/18:2 (Ala/L/L) and 18:3(n-6)/18:2/18:2 (Gla/L/L) in blackcurrant seed oil were determined by Ag-HPLC/APCI-MS and Ag-HPLC/ESI-MS/MS techniques. In the latter, silver ion adducts were prepared by adding silver nitrate to the postcolumn flow. A new Ag-HPLC solvent system containing nonchlorinated solvents for the separation of Gla- and Ala-containing TAGs is introduced. Ag-HPLC separation of Ala/L/L and Gla/L/L was sufficient and regioisomers sn-LnLL + sn-LLLn and sn-LLnL (Ln, linolenic acid) could be differentiated well with the MS methods used. No discrimination was made between the sn-1 and sn-3 positions. The results show that the methods used are suitable to discriminate and determine the regioisomeric structure of TAGs. The regioisomeric structure of TAG with the fatty acid combination Gla/L/L in blackcurrant seed oil was considered to be practically random (32.7-37.8% of sn-LGlaL). In the fatty acid combination Ala/L/L, the regioisomeric structure is nonrandom (7.3-12.1% of sn-LAlaL) with Ala preferentially in a primary position. It can be concluded that the positional distribution of Ala and Gla is different in Ln/L/L TAGs of blackcurrant seed oil.     

Malolactic fermentation in four varieties of sea buckthorn (Hippophaë rhamnoides L.)

Malolactic fermentation (MLF) used in winemaking was applied to four varieties of sea buckthorn (Hippophaë rhamnoides L.). Sensory properties and chemical components of fermented and unfermented juices were studied in order to see whether the MLF can have an effect on sensory quality of sea buckthorn and if there are differences between varieties. The juices were inoculated with unadapted Oenococcus oeni at a cell density of 10⁹ CFU/mL and the fermentation was performed over 18 h at 28 °C. The fermentation decreased sourness and astringency in the samples, and fruity flavor as well as fermented flavor were increased. However, the ML reaction was different between the varieties. The size of the reaction was not proportional to the initial pH or malic acid content of the juice. Larger the ML reaction, more changes were observed in the sensory properties.     

Composition and antioxidative activities of supercritical CO2-extracted oils from seeds and soft parts of northern berries

The present study investigated the composition and the antioxidative activities of oils from the seeds and the soft parts of a range of northern berries extracted by supercritical CO₂. The seed oils of the species of Rubus, Vaccinium, Empetrum, Fragaria and Hippophaë were rich in linoleic (18:2n-6, 34-55% of total fatty acids) and ??-linolenic (18:3n-3, 29-45% of total) acids with n-6:n-3 ratios of 1:1-1:2. The seed oils of the species Ribes contained, in addition to linoleic and ??-linolenic acids, ??-linolenic (18:3n-6) and stearidonic (18:3n-4) acids. In seed oils from European rowanberry (Sorbus aucuparia L.) and snowball berry (Viburnum opulus L.), linoleic and oleic (18:1n-9) acids together exceeded 90% of the total fatty acids. The sea buckthorn (SB) pulp oil had palmitoleic (16:1n-7), palmitic (16:0) and oleic acids as the major fatty acids. The SB pulp oil and snowball berry seed oil were rich in ??-tocopherol (120 and 110 mg/100 g oil, respectively), whereas raspberry seed oil contained a high level of ??-tocopherol (320 mg/100 g oil). Seed oils of cranberry (180 mg/100 g oil), Arctic cranberry (190 mg/100 g oil) and lingonberry (120 mg/100 g oil) are rich sources of ??-tocotrienol. The berry seed oils and the SB pulp oil showed varying peroxyl radical scavenging efficacies (300-2300 ??mol ??-tocopherol equivalent per 100 g oil) and inhibitory effects on perioxidation of microsomal lipids (250-1200 ??mol trolox equivalent per 100 g oil) in vitro. The peroxyl radical scavenging activity positively correlated with the total content of tocopherols and tocotrienols of the oils (r = 0.875, P = 0.001). The SB seed oil and pulp oil were active in scavenging superoxide anions produced by xanthine-xanthine oxidase system and inhibited Cu²⁺-induced LDL oxidation in vitro. The SB oils also protected purified DNA and rat liver homogenate from UV-induced DNA oxidation in vitro. The current research suggests potential of supercritical CO₂-extracted oils from northern berries as nutraceuticals and ingredients of functional foods.     

Authentication of berries and berry-based food products

Berries represent one of the most important and high-valued group of modern-day health-beneficial “superfoods” whose dietary consumption has been recognized to be beneficial for human health for a long time. In addition to being delicious, berries are rich in nutrients, vitamins, and several bioactive compounds, including carotenoids, flavonoids, phenolic acids, and hydrolysable tannins. However, due to their high value, berries and berry-based products are often subject to fraudulent adulteration, commonly for economical gain, but also unintentionally due to misidentification of species. Deliberate adulteration often comprises the substitution of high-value berries with lower value counterparts and mislabeling of product contents. As adulteration is deceptive toward customers and presents a risk for public health, food authentication through different methods is applied as a countermeasure. Although many authentication methods have been developed in terms of fast, sensitive, reliable, and low-cost analysis and have been applied in the authentication of a myriad of food products and species, their application on berries and berry-based products is still limited. The present review provides an overview of the development and application of analytical chemistry methods, such as isotope ratio analysis, liquid and gas chromatography, spectroscopy, as well as DNA-based methods and electronic sensors, for the authentication of berries and berry-based food products. We provide an overview of the earlier use and recent advances of these methods, as well as discuss the advances and drawbacks related to their application.     

Applications Are the Drivers in the Mobile Information Society

This short paper clarifies the thoughts of the future Mobile InformationSociety (MIS), ubiquitous access to the information services in wirelessenvironment. The key elements of MIS are explained as well as some of thechallenges MIS sets for the current research and skill development programsin academic and industrial environment.     

Quantitation of acyl migration during lipase-catalyzed acidolysis, and of the regioisomers of structured triacylglycerols formed

Various MLM-type (M, medium-chain fatty acids; L, long-chain fatty acids) structured triacylglycerols were produced in pilot- or small-scale packed-bed reactors by lipasecatalyzed acidolysis. The incorporation and acyl migration of octanoic acid were measured by gas chromatography and Grignard degradation, and ranged from 39.0 to 48.7% and 0.6 to 9.3%, respectively. Quantitation of triacylglycerol molecular species was performed by ammonia negative ion chemical ionization (NICI) mass spectrometry (MS). The proportion of ACN (acyl carbon number) 34 species that contained one C₁₈ fatty acid and two C_8∶0′ in samples analyzed, varied from 12.5 to 23.2%. The selected regioisomers MLM and MML within the ACN 34 species group were quantified by NICI tandem MS (MS/MS) and were in the range of 97.1 to 98.4% and 1.6 to 2.9%, respectively. There was no correlation between the level of acyl migration during lipase-catalyzed esterification and the level of regioisomers of the selected MLM-type triacylglycerols in the structured lipid samples.     

Polystyrene crosslinked with oligomeric and polymeric poly(dimethyl siloxane) derivatives. Thermal and dynamic mechanical studies

Styrene has been copolymerized with various bifunctional poly(dimethyl siloxane) cross-linkers having molar masses in the range 200–35,000. Calorimetric and rheological measurements show that the crosslinkers change T_g, T_ll, and T_exo, as well as melt viscosity and elasticity of polystyrene. These changes are strongly dependent on the molar mass of the crosslinker. Increasing the length of the siloxane crosslinker lowers T_g and melt viscosity, if the molar mass of the crosslinker is in a range 200–2000. Copolymerizing styrene with a bifunctional poly(dimethyl siloxane) having molar mass near 35,000 leads to a phase-separated polymer where polystyrene phase largely retains its original properties.     

SQUID magnetometers for low-frequency applications

We present a novel formulation for SQUID operation, which enables us to evaluate and compare the sensitivity and applicability of different devices. SQUID magnetometers for low-frequency applications are analyzed, taking into account the coupling circuits and electronics. We discuss nonhysteretic and hysteretic single-junction rf SQUIDs, but the main emphasis is on the dynamics, sensitivity, and coupling considerations of dc-SQUID magnetometers. A short review of current ideas on thin-film, dc-SQUID design presents the problems in coupling and the basic limits of sensitivity. The fabrication technology of tunnel-junction devices is discussed with emphasis on how it limits critical current densities, specific capacitances of junctions, minimum linewidths, conductor separations, etc. Properties of high-temperature superconductors are evaluated on the basis of recently published results on increased flux creep, low density of current carriers, and problems in fabricating reliable junctions. The optimization of electronics for different types of SQUIDs is presented. Finally, the most important low-frequency applications of SQUIDs in biomagnetism, metrology, geomagnetism, and some physics experiments demonstrate the various possibilities that state-of-the-art SQUIDs can provide.