Referate

Ohne Zusammenfassung     

Determination of fumigants in cereals and cereal products by capillary gas chromatography

Summary This study describes two methods for the quantitative determination of the residual fumigants ethylene dichloride (EDC), carbon tetrachloride (CCl₄), trichlorethylene (TCE), ethylene dibromide (EDB) and tetrachlorethylene (PCE) in cereals (especially wheat) and other foodstuffs. In the first method, a micro steam distillation- solvent extraction apparatus is used, while the second method is based on a headspace technique. For the quantitative determination of carbon tetrachloride in cereals, the multiple headspace technique is not retained because it is too time-consuming. The analysis of the different fumigants is performed by electron-capture gas chromatography, using a fused silica capillary column, CP sil 8 CB. With the steam distillation-solvent extraction method, recoveries from 95.9% to 100.5% are obtained for the fumigants, added at two different levels. The standard deviation varies between 1.1 % and 6%. Using the simple headspace technique, recoveries from 73.5% to 85.1 % with a standard deviation of between 1.7% and 6.6% have been reached for the fumigants in cereals fortified at two different levels. The absulute detection limits for the five fumigants EDC, CCl₄, TCE, EDB and PCE, in both methods, are 30, 0.25, 1.1, and 0.5 pg, respectively.

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Bestimmung von Begasungsmitteln in Getreide und Getreideprodukten durch Capillar-Gaschromatographie

Zusammenfassung Es wurden zwei Methoden für die quantitative Bestimmung der Restmengen von Begasungsmitteln wie 1,2-Dichlorethan (EDC), Tetrachlorkohlenstoff (CCl₄), Trichlorethylen (TCE), 1,2-Dibromethan (EDB) und Tetrachlorethylen (PCE) im Getreide, insbesondere Weizen, und in Lebensmitteln beschrieben. Das erste Verfahren basiert auf einer Mikrodampfdestillation-Lösungsmittelextraktion, während für das zweite die Kopfraumtechnik verwendet wurde. Da mehrfache Kopfraum-Extraktion bei der Bestimmung des Tetrachlorkohlenstoffes in Getreide zu zeitraubend ist, wurde diese Methode nicht beibehalten. Die Begasungsmittel wurden durch Elektroneneinfang-Gaschromatographie unter Verwendung einer CP sil. 8 CB silica Glaskolonne bestimmt. Mit der Dampfdestillation-Lösungsmittelextraktion wird eine Ausbeute von 95,9 bis 100,5% für fünf Begasungsrestmengen in zwei verschiedene Konzentrationen erreicht. Die Standardabweichung varriiert zwischen 1,1 und 6%. Die einfache Kopfraum-Extraktion gibt für zwei verschiedene Konzentrationen eine Ausbeute von 73,5 bis 85,1% mit einer Standardabweichung von 1,7 bis 6,6%. Die absolute Nachweisgrenze beider Methoden für die fünf Begasungsmittel EDC, CCl₄, TCE, EDB und PCE ist 30, respektive 0,25, 1,1 und 0,5 pg.

     

Determination of residual ethylene dibromide in cereals by glass capillary gas chromatography

Summary This study describes two methods for the quantitative determination of residual ethylene dibromide (1,2-dibromoethane) in cereals, especially wheat, and in dried fruit. The first method is based on a solvent-extraction technique; in the second a continuous micro steam-distillation — solvent-extraction apparatus is used. The quantitative determination of ethylene dibromide is performed by electron-capture gas chromatography using a glass capillary column coated with CPwax 51. The absolute detection limit for EDB is 0.5 pg and recoveries of 82 and 98% resp. are obtained for samples with EDB added in the range of 10 to 50 g/kg.75 samples of cereal products and 19 samples of dried fruit have been analysed with the solvent extraction method. For 22 samples the micro steam-distillation-solvent-extraction technique has been used.

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Bestimmung von Restmengen von Ethylendibromid in Getreide durch Capillar-Gaschromatographie

Zusammenfassung Es wurden zwei Methoden für die quantitative Bestimmung von Restmengen des Ethylendibromids (1,2-Dibromoethan) in Getreide, insbesondere Weizen, und in getrockneten Früchte beschrieben. Das erste Verfahren basiert auf der Lösungsmittelextraktions-Technik; für das zweite dagegen wurde ein Mikro-Dampfdestillation-Lösungsmit-telextraktions-Apparat verwendet. Ethylendibromid wird bestimmt durch Electroneneinfang-Gaschromatographie unter Verwendung einer mit CPwax 51 belegten Capillarglaskolonne. Die absolute Nachweisgrenze für EDB ist 0.5 pg und die Ausbeute im Gebiet von 10 bis 50 g/kg ist 82 resp. 98%.Insgesamt wurden 75 Getreideprodukte und 19 getrocknete Früchteproben mit der Lösungsmittelextraktions-Technik analysiert. Mit dem schnellen Mikro-Dampfdestillation-Lösungsmittelextraktions-Verfahren wurden 22 Getreideproben untersucht.

     

An Assistive VLC Technology for Smart Home Devices Using EOG

In recent years, assistive technology has been an emerging area of research to improve the quality of life, especially for the disabled and elderly people. In this paper, a novel electro-oculogram (EOG) signal based assistive visible light communication (VLC) in a smart home environment is presented. The eye movement is captured using silver chloride (AgCl) surface electrodes placed around eyes. The captured signal is further processed and transmitted using a VLC link to control smart home devices. To validate the proposed EOG-VLC based smart device control scheme, experiments were conducted. For the ease of the experiments, instead of an actual smart home device, we employed a digital door lock to verify its accurate control operation. Experiment results demonstrate that the proposed smart device control scheme operates accurately and reliably. Therefore, since the proposed scheme is based on a less hazardous VLC link, it is envisioned that the scheme can pave the way for greener and safer smart homes, particularly benefiting disabled and elderly people.     

Ciphertext-policy attribute-based encryption supporting access policy update and its extension with preserved attributes

Attribute-based encryption (ABE) allows one-to-many encryption with static access control. In many occasions, the access control policy must be updated, but the original encryptor might be unavailable to re-encrypt the message, which makes it impractical. Unfortunately, to date the work in ABE does not consider this issue yet, and hence this hinders the adoption of ABE in practice. In this work, we consider how to update access policies in ciphertext-policy attribute-based encryption (CP-ABE) systems efficiently without encrypting each ciphertext with new access policies. We introduce a new notion of CP-ABE supporting access policy update that captures the functionalities of attribute addition and revocation to access policies. We formalize the security requirements for this notion and subsequently construct two provably secure CP-ABE schemes supporting AND-gate access policy with constant-size ciphertext for user decryption. The security of our schemes are proved under the augmented multi-sequences of exponents decisional Diffie–Hellman assumption. We also present a different construction in which certain attributes in an access policy can be preserved by the original encryptor, while other attributes can be revoked efficiently so that the ability of attribute revocation can be appropriately restrained.     

Effects of dietary linseed oil and marine oil on lipid peroxidation in monkey liverin vivo andin vitro

Diets rich in linoleic acid (CO) from corn oil, or in linoleic acid and either α-linolenic acid (LO) based on linseed oil or n−3 fatty acids (MO) from menhaden oil were fed to male and female Cynomolgus monkeys for 15 wk. In the liver a 40% reduction of α-tocopherol occurred in the MO group relative to the CO and LO groups followed by increased formation of lipofuscinin vivo. A four-fold increase of α-tocopherol in the MO diet (MO+E) brought the level in the liver to that found with CO and LO. The increased peroxidation in the MO group in the liver phospholipids was associated with the replacement of 60% of the n−6 fatty acids by n−3 fatty acids from menhaden oil. Similar fatty acid profiles were found in groups fed MO and MO+E, respectively. Compared to the CO fed group, feeding α-linolenic acid only resulted in a slight incorporation of n−3 fatty acids in the liver membranes mainly due to a direct incorporation of α-linolenic acid. However, in monkeys fed menhaden oil more than 30% of the total fatty acids in the liver phospholipids were n−3 fatty acids. The various diets did not influence the activity of liver catalase (EC 1.11.1.6) nor superoxide dismutase (EC 1.15.1.1), but glutathione-peroxidase activity (EC 1.11.1.9) was higher in monkeys fed the MO diet. The catalase activity in females was 20% higher than in males. In anin vitro assay, liver microsomes from monkeys fed the MO diet or the MO diet supplemented with tocopherol produced similar amounts of thiobarbituric acid reactive substances and at a much higher rate than microsomes from the CO and LO groups. It appeared that α-tocopherol did not protect long-chain n−3 C₂₀ and C₂₂ fatty acids as well as n−6 fattya acids against peroxidation. The present data showed that monkeys were not fully able to compensate for increased peroxidative stress but a four-fold supplement of vitamin E to the diets reduced the oxidation.     

常温干防腐蚀涂料系用水性树脂

简述了水性丙烯酸乳液、水性醇酸乳液和水性双组分环氧树脂在水性防腐蚀涂料中的应用，并进行了耐湿热性能和耐盐雾性能的比较。     

Anionic copolymerization of butadiene and styryl-terminated polystyrene macromonomers

Summary For the preparation of graft copolymers of the type poly (butadiene-g-styrene), possibilities were investigated both of obtaining a living anionic copolymerization of butadiene and styryl-terminated polystyrene macromonomers and of assessing the necessary analytical prerequisites for determining the conversion. The course of this copolymerization can be observed by combining gravimetry with SEC. With the initiator system sodium tert-butoxide /n-butyl lithium there are only a few deviations from the statistically ideal course of copolymerization and the macromonomer is almost completely incorporated into the copolymer.     

The discrete time/resource trade-off problem in project networks: a branch-and-bound approach

In many solution methods for resource-constrained project scheduling, it is assumed that both the duration of each activity and its resource requirements are known and fixed. In real-life projects, however, it often occurs that only one renewable bottleneck resource is available and that the activities have a total work content which indicates how much work (expressed in man-periods) has to be performed. The objective then is to schedule each activity in one of its possible execution modes, subject to the precedence and resource constraints, in order to minimize the project makespan. We present a branch-and-bound procedure and report computational results, obtained using a full factorial experiment on a randomly generated problem set.