Engineering de novo disulfide bond in bacterial alpha-type carbonic anhydrase for thermostable carbon sequestration

Exploiting carbonic anhydrase (CA), an enzyme that rapidly catalyzes carbon dioxide hydration, is an attractive biomimetic route for carbon sequestration due to its environmental compatibility and potential economic viability. However, the industrial applications of CA are strongly hampered by the unstable nature of enzymes. In this work, we introduced in silico designed, de novo disulfide bond in a bacterial alpha-type CA to enhance thermostability. Three variants were selected and expressed in Escherichia coli with an additional disulfide bridge. One of the variants showed great enhancement in terms of both kinetic and thermodynamic stabilities. This improvement could be attributed to the loss of conformational entropy of the unfolded state, showing increased rigidity. The variant showed an upward-shifted optimal temperature and appeared to be thermoactivated, which compensated for the lowered activity at 25 degrees C. Collectively, the variant constructed by the rapid and effective de novo disulfide engineering can be used as an efficient biocatalyst for carbon sequestration under high temperature conditions.1194Ysciescopu

Spread of Mutant Middle East Respiratory Syndrome Coronavirus with Reduced Affinity to Human CD26 during the South Korean Outbreak

The newly emerging Middle East respiratory syndrome coronavirus (MERS-CoV) causes a severe respiratory infection with a high mortality rate (similar to 35%). MERS-CoV has been a global threat due to continuous outbreaks in the Arabian peninsula and international spread by infected travelers since 2012. From May to July 2015, a large outbreak initiated by an infected traveler from the Arabian peninsula swept South Korea and resulted in 186 confirmed cases with 38 deaths (case fatality rate, 20.4%). Here, we show the rapid emergence and spread of a mutant MERS-CoV with reduced affinity to the human CD26 receptor during the South Korean outbreak. We isolated 13 new viral genomes from 14 infected patients treated at a hospital and found that 12 of these genomes possess a point mutation in the receptor-binding domain (RBD) of viral spike (S) protein. Specifically, 11 of these genomes have an I529T mutation in RBD, and 1 has a D510G mutation. Strikingly, both mutations result in reduced affinity of RBD to human CD26 compared to wild-type RBD, as measured by surface plasmon resonance analysis and cellular binding assay. Additionally, pseudotyped virus bearing an I529T mutation in S protein showed reduced entry into host cells compared to virus with wild-type S protein. These unexpected findings suggest that MERS-CoV adaptation during human-to-human spread may be driven by host immunological pressure such as neutralizing antibodies, resulting in reduced affinity to host receptor, and thereby impairs viral fitness and virulence, rather than positive selection for a better affinity to CD26. IMPORTANCE Recently, a large outbreak initiated by an MERS-CoV-infected traveler from the Middle East swept South Korea and resulted in 186 confirmed cases with 38 deaths. This is the largest outbreak outside the Middle East, and it raised strong concerns about the possible emergence of MERS-CoV mutations. Here, we isolated 13 new viral genomes and found that 12 of them possess a point mutation in the receptor-binding domain of viral spike protein, resulting in reduced affinity to the human cognate receptor, CD26, compared to the wild-type virus. These unexpected findings suggest that MERS-CoV adaptation in humans may be driven by host immunological pressure.111819Ysciescopu

Road Damage Detection Acquisition System based on Deep Neural Networks for Physical Asset Management

Research on damage detection of road surfaces has been an active area of re-search, but most studies have focused so far on the detection of the presence of damages. However, in real-world scenarios, road managers need to clearly understand the type of damage and its extent in order to take effective action in advance or to allocate the necessary resources. Moreover, currently there are few uniform and openly available road damage datasets, leading to a lack of a common benchmark for road damage detection. Such dataset could be used in a great variety of applications; herein, it is intended to serve as the acquisition component of a physical asset management tool which can aid governments agencies for planning purposes, or by infrastructure mainte-nance companies. In this paper, we make two contributions to address these issues. First, we present a large-scale road damage dataset, which includes a more balanced and representative set of damages. This dataset is composed of 18,034 road damage images captured with a smartphone, with 45,435 in-stances road surface damages. Second, we trained different types of object detection methods, both traditional (an LBP-cascaded classifier) and deep learning-based, specifically, MobileNet and RetinaNet, which are amenable for embedded and mobile and implementations with an acceptable perfor-mance for many applications. We compare the accuracy and inference time of all these models with others in the state of the art

Mussel-Inspired Anisotropic Nanocellulose and Silver Nanoparticle Composite with Improved Mechanical Properties, Electrical Conductivity and Antibacterial Activity

Materials for wearable devices, tissue engineering and bio-sensing applications require both antibacterial activity to prevent bacterial infection and biofilm formation, and electrical conductivity to electric signals inside and outside of the human body. Recently, cellulose nanofibers have been utilized for various applications but cellulose itself has neither antibacterial activity nor conductivity. Here, an antibacterial and electrically conductive composite was formed by generating catechol mediated silver nanoparticles (AgNPs) on the surface of cellulose nanofibers. The chemically immobilized catechol moiety on the nanofibrous cellulose network reduced Ag+ to form AgNPs on the cellulose nanofiber. The AgNPs cellulose composite showed excellent antibacterial efficacy against both Gram-positive and Gram-negative bacteria. In addition, the catechol conjugation and the addition of AgNP induced anisotropic self-alignment of the cellulose nanofibers which enhances electrical and mechanical properties of the composite. Therefore, the composite containing AgNPs and anisotropic aligned the cellulose nanofiber may be useful for biomedical applications.open11128sciescopu

Chiral nematic self-assembly of minimally surface damaged chitin nanofibrils and its load bearing functions

Chitin is one of the most abundant biomaterials in nature, with 1010 tons produced annually as hierarchically organized nanofibril fillers to reinforce the exoskeletons of arthropods. This green and cheap biomaterial has attracted great attention due to its potential application to reinforce biomedical materials. Despite that, its practical use is limited since the extraction of chitin nanofibrils requires surface modification involving harsh chemical treatments, leading to difficulties in reproducing their natural prototypal hierarchical structure, i.e. chiral nematic phase. Here, we develop a chemical etching-free approach using calcium ions, called "natural way", to disintegrate the chitin nanofibrils while keeping the essential moiety for the self-assembly, ultimately resulting in the reproduction of chitin's natural chiral structure in a polymeric matrix. This chiral chitin nanostructure exceptionally toughens the composite. Our resultant chiral nematic phase of chitin materials can contribute to the understanding and use of the reinforcing strategy in nature.open119sciescopu

A semi-active H∞ control strategy with application to the vibration suppression of nonlinear high-rise building under earthquake excitations

Different from previous researches which mostly focused on linear response control of seismically excited high-rise buildings, this study aims to control nonlinear seismic response of high-rise buildings. To this end, a semi-active control strategy, in which H∞ control algorithm is used and magneto-rheological dampers are employed for an actuator, is presented to suppress the nonlinear vibration. In this strategy, a modified Kalman–Bucy observer which is suitable for the proposed semi-active strategy is developed to obtain the state vector from the measured semi-active control force and acceleration feedback, taking into account of the effects of nonlinearity, disturbance and uncertainty of controlled system parameters by the observed nonlinear accelerations. Then, the proposed semi-active H∞ control strategy is applied to the ASCE 20-story benchmark building when subjected to earthquake excitation and compared with the other control approaches by some control criteria. It is indicated that the proposed semi-active H∞ control strategy provides much better control performances by comparison with the semi-active MPC and Clipped-LQG control approaches, and can reduce nonlinear seismic response and minimize the damage in the buildings. Besides, it enhances the reliability of the control performance when compared with the active control strategy. Thus, the proposed semi-active H∞ control strategy is suitable for suppressing the nonlinear vibration of high-rise buildings

Task-specific reach-to-grasp training after stroke: Development and description of a home-based intervention

© The Author(s) 2015. This series of articles for rehabilitation in practice aims to cover a knowledge element of the rehabilitation medicine curriculum. Nevertheless they are intended to be of interest to a multidisciplinary audience. The competency addressed in this article is to transparently describe the process of developing a complex intervention for people after stroke as part of a feasibility randomised controlled trial. Objective: To describe and justify the development of a home-based, task-specific upper limb training intervention to improve reach-to-grasp after stroke and pilot it for feasibility and acceptability prior to a randomized controlled trial. Intervention description: The intervention is based on intensive practice of whole reach-to-grasp tasks and part-practice of essential reach-to-grasp components. A 'pilot' manual of activities covering the domains of self-care, leisure and productivity was developed for the feasibility study. The intervention comprises 14 hours of therapist-delivered sessions over six weeks, with additional self-practice recommended for 42 hours (i.e. one hour every day). As part of a feasibility randomized controlled trial, 24 people with a wide range of upper limb impairment after stroke experienced the intervention to test adherence and acceptability. The median number of repetitions in one-hour therapist-delivered sessions was 157 (interquartile range IQR 96-211). The amount of self-practice was poorly documented. Where recorded, the median amount of practice was 30 minutes (interquartile range 22-45) per day. Findings demonstrated that the majority of participants found the intensity, content and level of difficulty of the intervention acceptable, and the programme to be beneficial. Comments on the content and presentation of the self-practice material were incorporated in a revised 'final' intervention manual. Discussion: A comprehensive training intervention to improve reach-to-grasp for people living at home after stroke has been described in accordance with the Template for Intervention Description and Replication (TIDieR) reporting guidelines. The intervention has been piloted, and found to be acceptable and feasible in the home setting. Trial registration: ISRCTN5671658

Face-selective electrostatic control of hydrothermal zinc oxide nanowire synthesis

Rational control over the morphology and the functional properties of inorganic nanostructures has been a long-standing goal in the development of bottom-up device fabrication processes. We report that the geometry of hydrothermally grown zinc oxide nanowires can be tuned from platelets to needles, covering more than three orders of magnitude in aspect ratio (~0.1–100). We introduce a classical thermodynamics-based model to explain the underlying growth inhibition mechanism by means of the competitive and face-selective electrostatic adsorption of non-zinc complex ions at alkaline conditions. The performance of these nanowires rivals that of vapour-phase-grown nanostructures and their low-temperature synthesis (<60 °C) is favourable to the integration and in situ fabrication of complex and polymer-supported devices. We illustrate this capability by fabricating an all-inorganic light-emitting diode in a polymeric microfluidic manifold. Our findings indicate that electrostatic interactions in aqueous crystal growth may be systematically manipulated to synthesize nanostructures and devices with enhanced structural control.National Science Foundation (U.S.) (MIT Center for Bits and Atoms (NSF CCR0122419))Massachusetts Institute of Technology. Media LaboratoryKorea Foundation for Advanced StudiesSamsung Electronics Co. (research internship)Harvard University. Society of FellowsWallace H. Coulter Foundation (Early Career Award)Brain & Behavior Research Foundation (Young Investigator Award)National Science Foundation (U.S.)National Institutes of Health (U.S.) (Director’s New Innovator Award