An Ancestral Member of the Polysaccharide Lyase Family 2 Displays Endolytic Activity and Magnesium Dependence

Polysaccharide lyases (PLs) are enzymes that cleave glycosidic linkages in hexuronate polysaccharides, such as homogalacturonan (HG), using a β-elimination mechanism. Traditionally, PL activities on HG have been associated with catalytic calcium cofactors, unusually high pH optima, and arginine Brønstead bases. Recently, however, PL families that harness transition metal cofactors, utilize lysine and histidine Brønstead bases, and display more neutral pH optima have been described. One such family is PL2, which has members found primarily in phytopathogenic (e.g., Dickeya spp. and Pectobacterium spp.) or enteropathogenic (e.g., Yersinia spp.) bacterial species. PL2 is divided into two major subfamilies that are correlated with either an endolytic or exolytic activity. This study has focused on the activity of a PL2 member, which is not classified within either subfamily and helps to illuminate the origin of enzyme activities within the family. In addition, the role of Mg²⁺ as a preferential catalytic metal for an intracellular PL2 (PaePL2) is described. The implications for the relationship between catalytic metal selectivity and the cellular location of pectate lyase-mediated catalysis are discussed.     

A bound on the Wasserstein-2 distance between linear combinations of independent random variables

We provide a bound on a distance between finitely supported elements and general elements of the unit sphere of ${?}^2\left({\mathbb{N}}^1\right)$. We use this bound to estimate the Wasserstein-2 distance between random variables represented by linear combinations of independent random variables. Our results are expressed in terms of a discrepancy measure related to Nourdin–Peccati’s Malliavin–Stein method. The main application is towards the computation of quantitative rates of convergence to elements of the second Wiener chaos. In particular, we explicit these rates for non-central asymptotic of sequences of quadratic forms and the behavior of the generalized Rosenblatt process at extreme critical exponent.     

Experimental study of hydraulic engine mounts using multiple inertia tracks and orifices: Narrow and broad band tuning concepts

Hydraulic engine mount tuning concepts with one inertia track and one decoupler are well understood. However, the dynamic response with multiple tracks or orifices is not. To overcome this void in the literature, dynamic tuning concepts of hydraulic engine mounts, with emphasis on multiple (n-)inertia tracks/orifices, are experimentally examined. A new prototype mount concept is designed, built, and experimentally evaluated in a controlled manner. Refined linear time-invariant models of fixed decoupler-type designs are developed to critically assess the dynamic stiffness measurements and to explore a family of alternate designs. Three narrowband devices are investigated for accurately predicting the frequencies corresponding to peak loss angles for the first time, in addition to examining and validating an n = 3 track mount. Two broadband devices are also successfully evaluated by tuning damping introduced by orifice-type tracks. A special broad-tuned design utilizing a controlled ‘leakage’ path flow area is then suggested, and the role of fluid resistance in achieving the desired performance is clarified. Finally, a production mount with unknown configuration is diagnosed using the proposed models with n tracks.     

Automated capillary electrophoresis with on-line preconcentration by solid phase extraction using a sequential injection manifold and contactless conductivity detection

An extension of a capillary electrophoresis instrument coupled to a sequential injection analysis manifold was developed for automated measurements with on-line solid-phase extraction preconcentration. An in-house built capacitively coupled contactless conductivity detector was employed for sensitive detection with narrow capillaries of 25 μm internal diameter. The system was assembled into standardized 19 in. frames and racks for easy transport and mobile deployment. The system can be left running unattendedly without manual intervention with good operation stability. To demonstrate the application of the system, a method for the determination of four drugs, namely ibuprofen, diclofenac, naproxen and bezafibrate, was developed with enrichment factors of up to several hundreds. Detection of the drug residues down to the nM-scale was found possible and the method was found suitable for the detection of ibuprofen in the waste water of a hospital in Hanoi.     

Linear and nonlinear electromagnetic coupling models in vibration-based energy harvesting

This paper investigates the response of an energy harvester that uses electromagnetic induction to convert ambient vibration into electrical energy. A unique aspect of the present study is the comparison of the system's response behavior when either a linear or a physically motivated form of nonlinear coupling is applied. The motivating hypothesis for this work was that nonlinear coupling could be used to improve the performance of an energy harvester by broadening its frequency response. Combined theoretical and numerical studies investigate the harvester's response for both single and multi-frequency base excitation. Our investigations unveil regions in the parameter space where nonlinear coupling is better than linear coupling and regions where the opposite is true. The meaningful conclusion is that nonlinear coupling can sometimes be detrimental, but it can also be beneficial if properly designed into the system.