Subunit‐Specific Labeling of Ubiquitin Chains by Using Sortase: Insights into the Selectivity of Deubiquitinases

Information embedded in different ubiquitin chains is transduced by proteins with ubiquitin‐binding domains (UBDs) and erased by a set of hydrolytic enzymes referred to as deubiquitinases (DUBs). Understanding the selectivity of UBDs and DUBs is necessary for decoding the functions of different ubiquitin chains. Critical to these efforts is the access to chemically defined ubiquitin chains bearing site‐specific fluorescent labels. One approach toward constructing such molecules involves peptide ligation by sortase (SrtA), a bacterial transpeptidase responsible for covalently attaching cell surface proteins to the cell wall. Here, we demonstrate the utility of SrtA in modifying individual subunits of ubiquitin chains. Using ubiquitin derivatives in which an N‐terminal glycine is unveiled after protease‐mediated digestion, we synthesized ubiquitin dimers, trimers, and tetramers with different isopeptide linkages. SrtA was then used in combination with fluorescent depsipeptide substrates to effect the modification of each subunit in a chain. By constructing branched ubiquitin chains with individual subunits tagged with a fluorophore, we provide evidence that the ubiquitin‐specific protease USP15 prefers ubiquitin trimers but has little preference for a particular isopeptide linkage. Our results emphasize the importance of subunit‐specific labeling of ubiquitin chains when studying how DUBs process these chains.     

Filler Wetting in Miscible ESBR/SSBR Blends and Its Effect on Mechanical Properties

The selective wetting behavior of silica in emulsion styrene butadiene rubber (ESBR)/solution styrene butadiene rubber (SSBR) blends is characterized by the wetting concept, which is further developed for filled blends based on miscible rubbers. It is found that not only the chemical rubber–filler affinity but also the topology of the filler surface significantly influences the selective filler wetting in rubber blends. The nanopore structure of the silica surface has been recognized as the main reason for the difference in the wetting behavior of the branched ESBR molecules and linear SSBR molecules. However, the effect of nanopore structure becomes more significant in the presence of silane. It is discussed that the adsorption of silane on silica surface constricts the nanopore to some extent that hinders effectively the space filling of the nanopores by the branched ESBR molecules but not by the linear SSBR molecules. As a result, in silanized ESBR/SSBR blends the dominant wetting of silica surface by the tightly bonded layer of SSBR molecules causes a low‐energy dissipation in the rubber–filler interphase. That imparts the low rolling resistance to the blends similar to that of a silica‐filled SSBR compound, while the ESBR‐rich matrix warrants the good tensile behavior, i.e., good abrasion and wear resistance of the blends.

     

Multi-objective optimization of circular magnetic abrasive polishing of SUS304 and Cu materials

In this paper, a Multi-objective particle swarm optimization algorithm (MOPSOA) is applied to optimize surface roughness of workpiece after circular magnetic abrasive polishing. The most important parameters of polishing model, namely current, gap between pole and workpiece, spindle speed and polishing time, were considered in this approach. The objective functions of the MOPSOA depend on the quality of surface roughness of polishing materials with both simultaneous surfaces (Ra1, Ra2), which are determined by means of experimental approach with the aid of circular magnetic field. Finally, the effectiveness of the approach is compared between the optimal results with the experimental data. The results show that the new proposed polishing optimization method is more feasible.

     

A novel hybrid model of Bagging-based Naïve Bayes Trees for landslide susceptibility assessment

Bulletin of Engineering Geology and the Environment - Landslide susceptibility assessment was performed using the novel hybrid model Bagging-based Naïve Bayes Trees (BAGNBT) at Mu Cang Chai...     

Highly sensitive electrochemical sensor based on zirconium oxide-decorated gold nanoflakes nanocomposite 2,4-dichlorophenol detection

Journal of Applied Electrochemistry - In this study, a sensitive and selective electrochemical sensor based on a zirconia oxide-decorated gold nanoflake nanocomposite-modified glassy carbon...     

Using a Short Wavelength Infrared (SWIR) hyperspectral imaging system to predict alpha amylase activity in individual Canadian western wheat kernels

Sprout damage (pre-harvest germination) in wheat results in highly deleterious effects on end-product quality. Alpha-amylase, the pre-dominant enzyme in the early stage of sprouting has the most damaging effect. This paper introduces a new method using a SWIR hyperspectral imaging system (1000–2500 nm) to predict the α-amylase activity of individual wheat kernels. Two classes of Canadian wheat, Canada Western Red Spring (CWRS) and Canada Western Amber Durum (CWAD), with samples of differing degrees of sprout damage were investigated. Individual kernels were first imaged with the hyperspectral imaging system and then the α-amylase activity of each kernel was determined analytically. Individual kernel α-amylase activity prediction was significant (R ² 0.54 and 0.73) for CWAD and CWRS, respectively using Partial Least Square regression on the hyperspectral data. A classification method is proposed to separate CWRS kernels with high α-amylase activity level from those with low α-amylase activity giving an accuracy of above 80%. This work shows that hyper/multi-spectral imaging techniques can be used for rapidly predicting the α-amylase activity of individual kernels, detecting sprouting at early stage.     

试论石油天然气站场总图设计的矛盾特征

总图设计的任务是综合考虑工厂性质、规模、生产特点,满足运输和动力供应等要求,并结合当地条件,妥善处理厂区与厂外的关系,合理布置建(构)筑物、堆场、运输及动力设施等,全面地解决其间的协调问题,使建筑群体获得相应的艺术效果,以体现工厂建设的计划性、合理性、整体性,同时创造良好舒适的劳动、工作环境.     

Identification of depigmenting components from <Emphasis Type="Italic">Nigella glandulifera</Emphasis> Freyn

To develop a novel skin depigmenting agent from natural sources, the inhibition of melanogenesis by Chinese plants, N. glandulifrea, was evaluated. The methanol extract of this plant showed significantly down-regulated melanin synthesis in a dose-dependent manner at a non-toxic concentration in cultured B16F10 mouse melanoma cells. This extract was further fractionated by using solvent-solvent partition and silica open column chromatography to identify the active components. From GC-MS data, oleic acid methyl ester was found as one of the depigmenting agents. In conclusion, we suggest that this fraction may be a safe and effective depigmentation agent.     

Simulations of passivation phenomena based on discrete lattice gas automata

We present simulation results for a simple lattice gas cellular automata model of passivation. The lattice sites representing the corrosion product are produced at the corroding surface and diffuse executing a random walk. Asymmetric simple exclusion rules of the random walk account for an attractive potential between the corrosion product particles. The particles can aggregate and when sufficiently numerous form a compact phase on the corroding surface. The model predicts a transition from the active to passive state when increasing the reactivity of the surface. The transition is characterized by a sudden increase in the surface coverage of the corrosion product interpreted as a passive layer formation. The layer blocks contact of the metal surface with the environment and reduces the corrosion rate. The model reproduces the known paradox of passivity—the surface must be reactive enough for the layer to form. A further increase in the bare reactivity reduces largely the observed reaction rate. The simulations yield information on the morphological changes of the surface layer before and after the transition. In terms of the corrosion current, the active state is described by the current increase with the polarizing potential according to the Tafel law while in the passive state the current is independent of the anodic potential. Our simple model reproduces principal features of passivation.