We investigated the effect of nanocrystalline TiO2 doping on the electrochromic properties of tungsten trioxide (WO3) films. Here, we prepared various TiO2 nanocrystal-embedded amorphous WO3 films by ...a simple one-step dip-coating method. XRD data of the films show amorphous nature for both undoped and nanoparticle TiO2 doped WO3 films with anatase phase of TiO2 having (101) plane, which were further confirmed by TEM measurements. XPS of TiO2 doped WO3 film shows +6 oxidation state of W atom, implying the stoichiometric WO3 composition. The electrochromic properties of the films were investigated by in situ spectroelectrochemical methods, showing the markedly different behaviors of the films depending on the amount of nanocrystalline TiO2 doped. In particular, charge deintercalation kinetics of the films were significantly affected by the content of nanocrystalline TiO2 in amorphous WO3 matrix with 7 times faster deintercalation process by 30 wt% of TiO2 doping into WO3 at the expense of the reduced bleaching transmittance. This phenomenon may be associated with the effect of nanocrystalline TiO2 particles on blocking accessibility of Li ions to the trapping sites which has to be de-trapped if the ions are to be released.
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Tigecycline is regarded as a last-resort treatment for multidrug-resistant Acinetobacter baumannii. However, tigecycline resistance in A. baumannii has increased worldwide. In this study, we ...investigated tigecycline heteroresistance in A. baumannii isolates from South Korea. Antibiotic susceptibility testing was performed on 323 nonduplicated A. baumannii isolates. Among 260 and 37 tigecycline-susceptible and -intermediate-resistant A. baumannii isolates, 146 (56.2%) and 22 (59.5%) isolates were identified as heteroresistant to tigecycline through a disk diffusion assay and population analysis profiling. For selected isolates, an
time-kill assay was performed, and survival rates were measured after preincubation with diverse concentrations of tigecycline. Heteroresistant isolates showed regrowth after 12 h of 2× MIC of tigecycline treatment, and resistant subpopulations were selected by preexposure to tigecycline. Furthermore, genetic alterations in
, and
were assessed, and the relative mRNA expression levels of
and
were compared. The tigecycline resistance in subpopulations might be due to the insertion of IS
in
, leading to the overexpression of the AdeABC efflux pump. However, the tigecycline resistance of subpopulations was not stable during serial passages in antibiotic-free medium. The reversion of tigecycline susceptibility by antibiotic-free passages might occur by additional insertions of IS
in
and nucleotide alterations in
in some mutants. Tigecycline heteroresistance is prevalent in A. baumannii isolates, which results in treatment failure. Tigecycline resistance is mainly due to the overexpression of the AdeABC efflux pump, which is associated with genetic mutations, but this resistance could be reversed into susceptibility by additional mutations in antibiotic-free environments.
The evidence that antibiotic heteroresistance is responsible for treatment failure in clinical settings is increasing. Thus, detection and characterization of heteroresistance would be important for appropriate therapeutic guidance to treat bacterial infections. However, data on tigecycline heteroresistance in Gram-negative bacteria is currently limited, although tigecycline is regarded as a last-line antibiotic against infections caused by antibiotic-resistant pathogens. In this study, we investigated the tigecycline heteroresistance in Acinetobacter baumannii, which has been listed by the WHO as a priority for research and development of new antibiotics. We found very high prevalence of tigecycline-heteroresistant A. baumannii clinical isolates, which may result in treatment failure due to the selection of resistant subpopulations. We also identified the main resistance mechanism in tigecycline-resistant subpopulations, that is, upregulation of AdeABC efflux pumps due to IS
insertion in
Transparent and conducting flexible electrodes have been successfully developed over the last few decades due to their potential applications in optoelectronics. However, recent developments in smart ...electronics, such as a direct human-machine interface, health-monitoring devices, motion-tracking sensors, and artificially electronic skin also require materials with multifunctional properties such as transparency, flexibility and good portability. In such devices, there remains room to develop transparent and flexible devices such as pressure sensors or temperature sensors. Herein, we demonstrate a fully transparent and flexible bimodal sensor using indium tin oxide (ITO), which is embedded in a plastic substrate. For the proposed pressure sensor, the embedded ITO is detached from its Mayan-pyramid-structured silicon mold by an environmentally friendly method which utilizes water-soluble sacrificial layers. The Mayan-pyramid-based pressure sensor is capable of six different pressure sensations with excellent sensitivity in the range of 100 Pa-10 kPa, high endurance of 10
cycles, and good pulse detection and tactile sensing data processing capabilities through machine learning (ML) algorithms for different surface textures. A 5 × 5-pixel pressure-temperature-based bimodal sensor array with a zigzag-shaped ITO temperature sensor on top of it is also demonstrated without a noticeable interface effect. This work demonstrates the potential to develop transparent bimodal sensors that can be employed for electronic skin (E-skin) applications.
When a robot is teleoperated, its operator control is based on transmitted images. Network limitations and/or a remote distance usually cause delays or interruptions of the image transmission, which ...is one of the reasons for the instability of teleoperation systems. In this article, we propose a high-update-rate image generation method using past low update image and current grip position and electrical motor current of gripper received by sensors during teleoperation via a conditional generative adversarial network. The main challenge is that such a network can generate current high-update-rate images from past low-update-rate one, the current high-update-rate grip force, and the grip angle. We equipped a robot gripper with a camera and a grip force sensor and collected a large data set of robot vision, grip force, and grip angle sequences; objects with deformation, including irregular deformation, and rigid objects were tested in the experiment to verify the possibility of high-update-rate image generation under various grip conditions. We found that the proposed network allows the generation of current images with high update rate.
This paper proposes a Convolutional Neural Network (CNN) based approach for the classification and prediction of various types of in-plane and through-the-thickness delamination in smart composite ...laminates using low-frequency structural vibration outputs. An electromechanically coupled mathematical model is developed for the healthy and delaminated smart composite laminates, and their structural vibration responses are obtained in the time domain. Short Time Fourier Transform (STFT) is employed to transform the transient responses into two-dimensional spectral frame representation. A convolutional neural network is incorporated to distinguish between the damaged and undamaged states, as well as various types of damage of the laminated composites, by automatically extracting discriminative features from the vibration-based spectrograms. The CNN showed a classification accuracy of 90.1% on one healthy and 12 delaminated cases. The study of the confusion matrix of CNN provided further insights into the physics of the problem. The predictive performance of a pre-trained CNN classifier was also evaluated on unseen cases of delamination, and physically consistent results were obtained.
A deep-learning method for real-time video prediction is proposed that overcomes delays in the transmission of visual information in teleoperation. The proposed method predicts the real-time video ...frame from a delayed image using guidance information (the current master position and the delayed interaction force) transmitted from the robot. To predict accurate and realistic video frames, adversarial training is introduced. The generator in the GAN is composed of image encoders, a guidance-information embedder, and prediction decoders. To create the training data set, three experimenters remotely operated robots that gripped, picked up, and moved nine objects. Numerical results and predicted images are presented, verifying that the master position and the interaction force can be used effectively to predict the current video frame. The proposed method can reduce time-delay problems in teleoperation systems.
In this study, we investigated the effects of colistin resistance on virulence and fitness in hypermucoviscous (HV) Klebsiella pneumoniae sequence type 23 (ST23) strains. Colistin-resistant mutants ...were developed from three colistin-susceptible HV K. pneumoniae ST23 strains. The lipid A structures of strains were analyzed by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. Changes in HV were investigated using the string test, and extracellular polysaccharide production was quantified. The expression levels of the phoQ, pmrD, pmrB, pbgP, magA, and p-rmpA2 genes, serum resistance, and biofilm-forming activity were determined. The fitness of colistin-resistant mutants compared to that of the parental strains was examined by determining the competitive index (CI). The colistin-resistant mutants exhibited reduced HV, which was accompanied by decreased formation of capsular polysaccharides (CPS) and reduced expression of genes (magA and p-rmpA2). While there was enhanced expression of pmrD and pbgP in all colistin-resistant derivatives, there were differences in the expression levels of phoQ and pmrB between strains. MALDI-TOF analysis detected the addition of aminoarabinose or palmitate to the lipid A moiety of lipopolysaccharide in the colistin-resistant derivatives. In addition, survival rates in the presence of normal human serum were decreased in the mutant strains, and CI values (0.01 to 0.19) indicated significant fitness defects in the colistin-resistant derivatives compared to the respective parental strains. In hypervirulent HV K. pneumoniae strains, the acquisition of colistin resistance was accompanied by reduced CPS production, impaired virulence, and a significant fitness cost.
CrrAB two-component regulatory system is associated with colistin resistance in
Klebsiella pneumoniae
. Recently, some
K. pneumoniae
isolates lacking
crrAB
genes have been identified. In this study, ...we investigated the distribution and structural variation of the
crrBAC-kexD
cluster. To evaluate the structural variation of the
crrBAC-kexD
cluster, we explored 59 clinical
K. pneumoniae
isolates from Korea, and 508 whole genomes of
K. pneumoniae
and other strains of
Klebsiella
sp. Significant structural variations in
crrBAC-kexD
and its surrounding regions were identified among
K. pneumoniae
genomes. Within the genus
Klebsiella
, the cluster was identified only in
K. pneumoniae
,
K. variicola
, and
K. quasipneumoniae
, which form the
K. pneumoniae
complex. Among the 304 available
K. pneumoniae
genomes, an intact
crrBAC-kexD
cluster was identified in 178 isolates (58.6%), while the cluster was absent in 90 isolates (29.6%). Partial deletions within the cluster were identified in 22 genomes (7.2%). The most diverse structural patterns of the
crrBAC-kexD
cluster were observed in ST11 strains. Some clades lacked the
crrBAC-kexD
cluster. The
crrBAC-kexD
cluster was identified in the genomes of other bacterial species, including
Citrobacter freundii
and
Enterobacter ludwigii.
The
crrBAC-kexD
cluster is proposed to have been acquired by the ancestor of the
K. pneumoniae
complex from other bacterial species and the cluster may have been lost and re-acquired repeatedly in
K. pneumoniae
strains according to the phylogenetic analysis. The dynamic evolution of the
crrBAC-kexD
cluster suggests that it may have other roles, in addition to colistin resistance, in bacterial physiology.
Humans can approximately infer the force of interaction between objects using only visual information because we have learned it through experiences. Based on this idea, in this paper, we propose a ...method based on a recurrent convolutional neural network that uses sequential images to infer the interaction force without using a haptic sensor. To train and validate deep learning methods, we collected a large number of images and corresponding data concerning the interaction forces between objects shown therein through an electronic motor-based device. To focus on the changing appearances of a target object owing to external force in the images, we develop a sequential image-based attention module that learns a salient model from temporal dynamics for predicting unknown interaction forces. We propose a sequential image-based spatial attention module and a sequential image-based channel attention module, which are extended to exploit multiple images based on corresponding weighted average pooling layers. Extensive experimental results verified that the proposed method can successfully infer interaction forces in various conditions featuring different target materials, changes in illumination, and directions of external forces.
Antibiotic resistance is a global concern in public health. Antibiotic-resistant clones can spread nationally, internationally, and globally. This review considers representative antibiotic-resistant ...Gram-negative bacterial clones–CTX-M- 15-producing ST131 in
Escherichia coli
, extended-spectrum ß-lactamase-producing ST11 and KPC-producing ST258 in
Klebsiella pneumoniae
, IMP-6-producing, carbapenem-resistant ST235 in
Pseudomonas aeruginosa
, and OXA-23-producing global clone 2 in
Acinetobacter baumannii
–that have disseminated worldwide, including in Korea. The findings highlight the urgency for systematic monitoring and international cooperation to suppress the emergence and propagation of antibiotic resistance.
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