Two novel cyclodextrin-degrading enzymes isolated from thermophilic bacteria have similar domain structures but differ in oligomeric state and activity profile

In this paper, we present the expression and characterization of two novel enzymes from the alpha-amylase family exhibiting cyclomaltodextrinase specificity. The nucleotide sequences encoding the enzymes were isolated from the genomic DNA of two thermophilic bacterial strains originating from Icelandic hot springs and belonging to the genera Anoxybacillus (AfCda13) and Laceyella (LsCda13). The genes were amplified using a consensus primer strategy utilizing two of the four conserved regions present in glycoside hydrolase family 13. No identifiable signal peptides were present in open reading frames encoding the enzymes, indicating an intracellular location of both enzymes, and their physiological function to be intracellular cyclodextrin degradation. The domain structures of both enzymes were also similar, including an N-terminal domain, the catalytic module composed of the A- and B-domains, and a C-terminal domain. Despite the similarity in domain composition, the two enzymes displayed differences in the oligomeric state with AfCda13 being a dimeric protein, whereas LsCda13 was monomeric. The two enzymes also displayed significantly different activity profiles, despite being active on the same range of substrates. It was shown that the enzyme displaying the highest activity on cyclodextrin was dimeric (AfCda13). Moreover, a fraction of the dimeric enzyme could be converted to a monomeric state in the presence of KCl and this fraction retained only 23% of its activity on alpha-cyclodextrin while its activity on starch was not significantly affected, indicating that the oligomeric state is an important factor for a high activity on cyclodextrin substrates.     

Integrated microfluidic preconcentrator and immunobiosensor

We present a microfluidic biosensor that integrates membrane-based preconcentration with fluorescence detection. The concentration membrane was fabricated in polyacrylamide by an in situ photopolymerization technique at the junction of glass microchannels. Liposomes entrapping sulforhodamine B dye molecules were used for signal amplification. The biotin–streptavidin binding system was a model system for evaluating device performance. Biotinylated liposomes were preconcentrated at the membrane by applying an electric field across the membrane. The electric field causes the liposomes to migrate toward the membrane where they are concentrated by a sieving effect. Two orders of magnitude concentration was achieved after applying the electric field for only 2 min. The concentrated bolus was then eluted toward the detection unit, where the biotinylated liposomes were captured by immobilized streptavidin. The integrated system with the preconcentration module shows a 14-fold improvement in signal as opposed to a system that does not include preconcentration.     

Computed-Tomography-Based Analysis of Voids in SnBi57Ag1 Solder Joints and Their Influence on the Reliability

The first area of research in this article focuses on the characterization of solder joints that contain voids by means of computed tomography (CT). This non-destructive test method made it possible to detect both cracks and voids in solder joints, to define their precise positions, and to capture the void volume of each void. In addition to CT, we carried out metallographic examinations so that we could demonstrate the interaction of both methods. In the process, CT was used to localize the defect and metallography to display the defect in high resolution. The article goes on to discuss the question of whether voids have an effect on the thermo-mechanical reliability of SnBi57Ag1 solder joints. For this purpose, the solder joints were first classified by their void area ratio using radioscopy. In order to analyze the effect of the void area ratio on the reliability of the joint, the assembly underwent an accelerated aging process through thermal shock testing according to IPC 9701. Subsequently, the shocked assemblies were sheared. With the shear values after 1000 cycles, we were able to show that the voids affect the reliability of the SnBi57Ag1 solder joints only slightly and that the joints were hardly damaged. By means of CT examinations performed prior to the thermal shocks, cracks starting from the meniscus tip could be attributed to the temperature changes. These cracks may be crucial when they occur with cracks found on macrovoids inside the meniscus.     

Receptor binding sites and antigenic epitopes on the fiber knob of human adenovirus serotype 3

The adenovirus fiber knob causes the first step in the interaction of adenovirus with cell membrane receptors. To obtain information on the receptor binding site(s), the interaction of labeled cell membrane proteins to synthetic peptides covering the adenovirus type 3 (Ad3) fiber knob was studied. Peptide P6 (amino acids [aa] 187 to 200), to a lesser extent P14 (aa 281 to 294), and probably P11 (aa 244 to 256) interacted specifically with cell membrane proteins, indicating that these peptides present cell receptor binding sites. Peptides P6, P11, and P14 span the D, G, and I beta-strands of the R-sheet, respectively. The other reactive peptides, P2 (aa 142 to 156), P3 (aa 153 to 167), and P16 (aa 300 to 319), probably do not present real receptor binding sites. The binding to these six peptides was inhibited by Ad3 virion and was independent of divalent cations. We have also screened the antigenic epitopes on the knob with recombinant Ad3 fiber, recombinant Ad3 fiber knob, and Ad3 virion-specific antisera by enzyme-linked immunosorbent assay. The main antigenic epitopes were presented by P3, P6, P12 (aa 254 to 269), P14, and especially the C-terminal P16. Peptides P14 and P16 of the Ad3 fiber knob were able to inhibit Ad3 infection of cells.     

Parallel processing of objects in a naming task.

The authors investigated whether speakers who named several objects processed them sequentially or in parallel. Speakers named object triplets, arranged in a triangle, in the order left, right, and bottom object. The left object was easy or difficult to identify and name. During the saccade from the left to the right object, the right object shown at trial onset (the interloper) was replaced by a new object (the target), which the speakers named. Interloper and target were identical or unrelated objects, or they were conceptually unrelated objects with the same name (e.g., bat [animal] and [baseball] bat). The mean duration of the gazes to the target was shorter when interloper and target were identical or had the same name than when they were unrelated. The facilitatory effects of identical and homophonous interlopers were significantly larger when the left object was easy to process than when it was difficult to process. This interaction demonstrates that the speakers processed the left and right objects in parallel. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Processing of Extrafoveal Objects During Multiple-Object Naming.

In 3 experiments, the authors investigated the extent to which objects that are about to be named are processed prior to fixation. Participants named pairs or triplets of objects. One of the objects, initially seen extrafoveally (the interloper), was replaced by a different object (the target) during the saccade toward it. The interloper-target pairs were identical or unrelated objects or visually and conceptually unrelated objects with homophonous names (e.g., animal- baseball bat). The mean latencies and gaze durations for the targets were shorter in the identity and homophone conditions than in the unrelated condition. This was true when participants viewed a fixation mark until the interloper appeared and when they fixated on another object and prepared to name it while viewing the interloper. These results imply that objects that are about to be named may undergo far-reaching processing, including access to their names, prior to fixation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

造纸自动化方面的创新趋势

造纸过程自动化系统的发展趋势是传感器整合到设备中;更侧重过程分析;具有可供数据整合的信息系统,质量控制和工艺控制日益通过DCS工具来联系和实现.这将改善工艺控制并且可以更快地进行扰动分析,确定技术上种种复杂的相互关系.