Bestimmung des Herbicids Glyphosat und dessen Hauptmetabolit Aminomethylphosphons?ure (AMPA) in Trinkwasser mit Hilfe der HPLC

Zusammenfassung Es wird eine Methode zur Bestimmung von Glyphosat und dessen Hauptmetabolit Aminomethylphosphonsäure (AMPA) in Trinkwasser beschrieben, die es erlaubt, den in der Schweiz geforderten Toleranzwert von 0,1 g/1 zu erreichen (Nachweisgrenze 0,02 g/l). Die Wasserprobe wird dabei direkt mit 9-Fluorenylmethyl-chloroformaat (FMOCCI) versetzt, um extrahierbare und gleichzeitig fluorescierende Derivate zu erhalten. Diese werden nach Ausschütteln mit einem organischen Lösungsmittelgemisch durch HPLC mit Fluorescenzdetektor bestimmt. In bisher 151 untersuchten Trinkwasserproben des Kantons Bern konnten weder Glyphosat noch AMPA nachgewiesen werden.

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Determination of glyphosate herbicide and its main metabolite aminomethylphosphonic acid (AMPA) in drinking water by HPLC

Summary A method for the determination of glyphosate and its major metabolite aminomethylphosphonic acid (AMPA) is described. With a detection limit of 0.02 g/l, the method suitably fulfills the requirements of the Swiss legislation (tolerance value of 0.1 g/l water). The compounds are derivatized directly in the original water sample with 9-fluorenylmethyl chloroformate (FMOCCI) in order to obtain extractable and fluorescent derivatives. These are extracted with organic solvents and determined by HPLC using a fluorescence detector. Neither of the compounds could be detected in 151 tap water samples from the Canton of Berne.

     

Post-Translational Modifications of Retroviral HIV-1 Gag Precursors: An Overview of Their Biological Role

Protein post-translational modifications (PTMs) play key roles in eukaryotes since they finely regulate numerous mechanisms used to diversify the protein functions and to modulate their signaling networks. Besides, these chemical modifications also take part in the viral hijacking of the host, and also contribute to the cellular response to viral infections. All domains of the human immunodeficiency virus type 1 (HIV-1) Gag precursor of 55-kDa (Pr55^Gag), which is the central actor for viral RNA specific recruitment and genome packaging, are post-translationally modified. In this review, we summarize the current knowledge about HIV-1 Pr55^Gag PTMs such as myristoylation, phosphorylation, ubiquitination, sumoylation, methylation, and ISGylation in order to figure out how these modifications affect the precursor functions and viral replication. Indeed, in HIV-1, PTMs regulate the precursor trafficking between cell compartments and its anchoring at the plasma membrane, where viral assembly occurs. Interestingly, PTMs also allow Pr55^Gag to hijack the cell machinery to achieve viral budding as they drive recognition between viral proteins or cellular components such as the ESCRT machinery. Finally, we will describe and compare PTMs of several other retroviral Gag proteins to give a global overview of their role in the retroviral life cycle.     

Insights into the Action Mechanism of the Antimicrobial Peptide Lasioglossin III

Lasioglossin III (LL-III) is a cationic antimicrobial peptide derived from the venom of the eusocial bee Lasioglossum laticeps. LL-III is extremely toxic to both Gram-positive and Gram-negative bacteria, and it exhibits antifungal as well as antitumor activity. Moreover, it shows low hemolytic activity, and it has almost no toxic effects on eukaryotic cells. However, the molecular basis of the LL-III mechanism of action is still unclear. In this study, we characterized by means of calorimetric (DSC) and spectroscopic (CD, fluorescence) techniques its interaction with liposomes composed of a mixture of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-rac-phosphoglycerol (POPG) lipids as a model of the negatively charged membrane of pathogens. For comparison, the interaction of LL-III with the uncharged POPC liposomes was also studied. Our data showed that LL-III preferentially interacted with anionic lipids in the POPC/POPG liposomes and induces the formation of lipid domains. Furthermore, the leakage experiments showed that the peptide could permeabilize the membrane. Interestingly, our DSC results showed that the peptide-membrane interaction occurs in a non-disruptive manner, indicating an intracellular targeting mode of action for this peptide. Consistent with this hypothesis, our gel-retardation assay experiments showed that LL-III could interact with plasmid DNA, suggesting a possible intracellular target.     

细磨活化对白钨矿浸取行为的影响SCIEI

本文研究了细磨活化对白钨矿浸取行为的影响.实验结果表明,细磨活化后白钨矿在HCl-Na_3PO_4介质中的浸出速率显著加快,钨的浸出率由原来的约8％提高到99％以上.红外光谱和X射线分析结果表明,细磨除了使白钨矿比表面积显著增大外,还在固体的表面和内部产生缺陷结构,增加了矿物表面的反应活性,改善了白钨矿的分解,使得白钨矿的浸出能在较低的温度顺利进行。     

A kinetic study of the adsorption and desorption process of two commercial molecular sieves

A mathematical model and its numerical solution is presented to describe adiabatic adsorption—desorption processes in a fixed bed when the mass and heat transfer can be described by external film transfer coefficients only, which is especially interesting in the case of non-uniform, irregular particles. A new method to measure such rates is presented, based on continuous weighing of a through-circulated bed. The measured rates can be checked against the difference in humidity and temperature between the outlet and inlet air in order to minimize errors.The comparison between experimental results and calculations showed that the adsorption process in a bed of molecular sieve pellets can not be described with a constant mass transfer coefficient; the desorption process is better described although not entirely satisfactorily. In the case of a honeycomb molecular sieve, a constant mass transfer coefficient described both the adsorption and desorption processes satisfactorily.     

Testing usability and trainability of indirect touch interaction: perspective for the next generation of air traffic control systems

This study aims to determine whether indirect touch device can be used to interact with graphical objects displayed on another screen in an air traffic control (ATC) context. The introduction of such a device likely requires an adaptation of the sensory-motor system. The operator has to simultaneously perform movements on the horizontal plane while assessing them on the vertical plane. Thirty-six right-handed participants performed movement training with either constant or variable practice and with or without visual feedback of the displacement of their actions. Participants then performed a test phase without visual feedback. Performance improved in both practice conditions, but accuracy was higher with visual feedback. During the test phase, movement time was longer for those who had practiced with feedback, suggesting an element of dependency. However, this ‘cost’ of feedback did not extend to movement accuracy. Finally, participants who had received variable training performed better in the test phase, but accuracy was still unsatisfactory. We conclude that continuous visual feedback on the stylus position is necessary if tablets are to be introduced in ATC.     

OCOG: A common grasp computation algorithm for a set of planar objects

This paper addresses the problem of defining a simple End-Effector design for a robotic arm that is able to grasp a given set of planar objects. The OCOG (Objects COmmon Grasp search) algorithm proposed in this paper searches for a common grasp over the set of objects mapping all possible grasps for each object that satisfy force closure and quality criteria by taking into account the external wrenches (forces and torque) applied to the object. The mapped grasps are represented by feature vectors in a high-dimensional space. This feature vector describes the design of the gripper. A database is generated for all possible grasps for each object in the feature vector space. A search algorithm is then used for intersecting all possible grasps over all parts and finding a common grasp suitable for all objects. The search algorithm utilizes the kd-tree index structure for representing the database of the sets of feature vectors. The kd-tree structure enables an efficient and low cost nearest-neighbor search for common vectors between the sets. Each common vector found (feature vector) is the grasp configuration for a group of objects, which implies the future end-effector design. The final step classifies the grasps found to subsets of the objects, according to the common vectors found. Simulations and experiments are presented for four objects to validate the feasibility of the proposed algorithm. The algorithm will be useful for standardization of end-effector design and reducing its engineering time.     

Chemical inhibitors when timing is critical: a pharmacological concept for the maturation of T cell contacts

Cellular signal transduction proceeds through a complex network of molecular interactions and enzymatic activities. The timing of these molecular events is critical for the propagation of a signal and the generation of a specific cellular response. To define the timing of signalling events, we introduce the combination of high-resolution confocal microscopy with the application of small-molecule inhibitors at various stages of signal transduction in T cells. Inhibitors of Src-family tyrosine kinases and actin dynamics were employed to dissect the role of the lymphocyte-specific tyrosine kinase Lck in the formation and maintenance of T cell receptor/CD3-dependent contacts. Anti-CD3epsilon-coated coverslips served as a highly defined stimulus. The kinetics of the recruitment of the yellow fluorescent protein-tagged signalling protein ZAP-70 were detected by high-resolution confocal microscopy. The analysis revealed that at 5 min after receptor engagement, Lck activity was required for maintenance of contacts. In contrast, after 20 min of receptor engagement, the contacts were Lck-independent. The relevance of the timing of inhibitor application provides a pharmacological concept for the maturation of T cell-substrate contacts.     

Destabilizing interactions between the partners of a bifunctional fusion protein

Hybrid MalE–GVP is a bifunctional protein in vitro sinceit binds maltose as protein MalE of Escherichia coli and sinceit is dimeric and specifically binds single-stranded DNA asprotein GVP of phage M13. The oxidation rate of a unique cysteineresidue was used to compare the stabilities of GVP in its freeand hybrid forms, under conditions where MalE was either foldedor unfolded by a denaturing agent. The results showed that boththe covalent link and tertiary non-covalent interactions betweenMalE and GVP destabilized GVP in MalE–GVP. To test whetherGVP had identical structures in its free and hybrid forms, mutationswere used as local conformational probes. The effects of thesemutations on the capabilities of MalE–GVP to dimerizeand to bind single-stranded DNA were assayed in vitro. Theywere compatible with the effects of the same mutations on theglobal activity of free GVP in vivo and with the effects thatcould be predicted from the known data on free GVP, in particularits crystal structure. Thus, one partner of a hybrid proteincan be destabilized by the other partner while maintaining itsstructural and functional characteristics.     

Combination of non-thermal plasma and heterogeneous catalysis for oxidation of volatile organic compounds: Part 2. Ozone decomposition and deactivation of γ-Al2O3

The role of ozone was studied for two different configurations combining non-thermal plasma (NTP) and heterogeneous catalysis, namely the use of a gas phase plasma with subsequent exposure of the effluent to a catalyst in a packed-bed reactor (post-plasma treatment) and the placement of the catalyst directly in the discharge zone (in-plasma catalysis). Non-porous and porous alumina and silica were deployed as model catalysts. The oxidation of immobilised hydrocarbons, toluene as a volatile organic compound and CO as an inorganic pollutant were studied in both operational modes.

While conversion and selectivity of hydrocarbon oxidation in the case of catalytic post-plasma treatment can be fully explained by the catalytic decomposition of O₃ on γ-Al₂O₃, the conversion processes for in-plasma catalysis are more complex and significant oxidation was also measured for the other three materials (-Al₂O₃, quartz and silica gel). It became obvious that additional synergetic effects can be utilised in the case of in-plasma catalysis due to short-lived species formed in the NTP.

The capability of porous alumina for ozone decomposition was found to be correlated with its activity for oxidation of carbon-containing agents. It could be clearly shown that the reaction product CO₂ poisons the catalytic sites at the γ-Al₂O₃ surface. The catalytic activity for O₃ decomposition can be partially re-established by NTP treatment. However, for practical purposes the additional reaction pathways provided by in-plasma catalytic processes are essential for satisfactory conversion and selectivity.