Search

Syntactic foams with fly ash cenospheres or commercial microballoons as fillers have been widely used in various applications ranging from aerospace to marine fields and the automotive industry. However, these two extensively adopted fillers possess multiple shortcomings, such as variations in the composition, material degeneration and distinct structural heterogeneity, which will inevitably hamper accurate prediction of the structure-property relationship and the corresponding design of the syntactic foams, reducing material utilization. Here, we present a microfluidic-based approach integrated with a subsequent heat treatment process to engineer syntactic foam fillers with a predefined composition, specified dimensional scope and reduced structural heterogeneity. These fillers are fully guaranteed by the synergy of the flexible and controllable generation of droplet templates with hydrodynamic regulation and rational selection of the nanoparticle dynamic response with respect to the heating temperature. In addition, two distinct surface morphologies have been observed with a temperature demarcation point of 1473 K, further endowing the fillers with multiplicity and optionality, simultaneously laying the foundation to regulate the properties of the syntactic foams through the diversity of the filler selection. Then, we fabricated a syntactic foam specimen by mold casting, and the integrity of the fillers inside was verified using an elaborate buoyancy comparison experiment, exhibiting its potential value in lightweight related applications. As the fillers derived from our approach show significant advantages over conventional ones, they will provide considerable benefits for the regulation and improvement of syntactic foam fillers in many practical applications.

The rise of multidrug resistant (MDR) Gram-negative (GN) pathogens and the decline of available antibiotics that can effectively treat these severe infections are a major threat to modern medicine. Developing novel antibiotics against MDR GN pathogens is particularly difficult as compounds have to permeate the GN double membrane, which has very different physicochemical properties, and have to circumvent a plethora of resistance mechanisms such as multiple efflux pumps and target modifications. The bacterial type II topoisomerases DNA gyrase (GyrA

The wire and cable wire diameter extrusion system is a nonlinear system with large hysteresis and strong coupling. Conventional PID control has poor control effect on the nonlinear system and low control precision. The coupling between melt temperature and melt pressure is decoupled to eliminate the coupling. First, based on the preliminary production and experimental data, the mathematical model of the controlled object control loop is established by system identification. Secondly, according to the actual decoupling control system, the system model matrix and the decoupling controller matrix are designed, and the controller of the system is designed by the expected dynamic method to construct the decoupling control model. Finally, compared with the feedforward decoupling control, the simulation results show that the robustness and dynamic performance of the system using the expected dynamic method are significantly improved.

Supplementation of probiotics is a promising gut microbiota-targeted therapeutic method for hyperlipidemia and atherosclerosis. However, the selection of probiotic candidate strains is still empirical. Here, we obtained a human-derived strain, Lactobacillus mucosae A1, which was shown by metagenomic analysis to be promoted by a high-fiber diet and associated with the amelioration of host hyperlipidemia, and validated its effect on treating hyperlipidemia and atherosclerosis as well as changing structure of gut microbiota in ApoE-/- mice on a Western diet. L. mucosae A1 attenuated the severe lipid accumulation in serum, liver and aortic sinus of ApoE-/- mice on a Western diet, while it also reduced the serum lipopolysaccharide-binding protein content of mice, reflecting the improved metabolic endotoxemia. In addition, L. mucosae A1 shifted the gut microbiota structure of ApoE-/- mice on a Western diet, including recovering a few members of gut microbiota enhanced by the Western diet. This study not only suggests the potential of L. mucosae A1 to be a probiotic in the treatment of hyperlipidemia and atherosclerosis, but also highlights the advantage of such function-based rather than taxonomy-based strategies for the selection of candidate strains for the next generation probiotics.

We present a novel approach that utilizes thermal buoyancy convection to achieve flexible particle focusing and switching in continuous flow of a microfluidic system. In this platform, three strip microheaters, A, B, and C, are symmetrically distributed at the bottom of microchannel, and they are isolated from the particle suspension by a thin glass slide. Continual transverse convection flow forms when the microheaters are energized by dc signals. The flow patterns are readily tuned by changing the energization strategies of the microheater array, leading to the modulation of the position of flow stagnation region. Accordingly, microparticles dispersed in fluids are rapidly focused to the flow stagnation region by the Stokes drag and thus form a continuous particle beam. The particle beam can also be switched to different lateral positions by adjusting the control voltages. This particle manipulation method is first demonstrated by respectively energizing these three microheaters and subsequently switching silica particles into different outlets. The lateral position of the particle beam then is flexibly controlled by simultaneously energizing microheaters A and B (or B and C) and adjusting the voltage applied on microheater A (or C). Furthermore, the versatility of this approach is proved by focusing and switching of microsized droplets, that is, oil-in-water and water-in-oil-in-water emulsion droplets. Finally, we use poly(ethylene glycol) diacrylate microgels, excellent reactant carriers, as an experimental sample and flexibly manipulate them in this microdevice, demonstrating this strategy's applicability for the cargo delivery. Therefore, this technique can be attractive for many particle preprocessing applications.

There is increasing interest in the “Internet of Things” (IoT) and the development of wearable intelligent devices with human–machine interfaces (HMIs). Flexible touch panels have received wide attention because they are intuitive HMIs. However, most existing flexible touch panels can only detect a single touch or rely on massive electrodes and complex sensor arrays for multi-touch detection. Herein, a long service life (>5 months), wearable, and Multifunctional HMI (MHMI) with only two electrodes is reported for various applications. An anti-drying, transparent, ion-conducting, and tough organohydrogel with satisfactory stretchability (>450%) and long life is developed as a sensing material. A parallel mutual inspection detection structure based on ion conductors is designed to detect single or multiple touches accurately and sensitively. This structure comprises a pair of organohydrogel strips in a horizontal or spiral form embedded in a flexible substrate to construct one-dimensional (1D) or two-dimensional (2D) MHMIs. The 1D- and 2D-MHMIs can be used as linear controllers and 2D movement controllers, respectively. The multi-touch recognition function endows the MHMIs with greater operability by programmatically implementing multi-device switching and multi-function selection in a versatile and effective manner. Therefore, the devices have great potential for use in the IoT-related applications.

In this paper, two nitrite ion sensing nanocomposites based on a magnetic-emissive core–shell structure were designed and synthesized, using Fe 3 O 4 particles as core, a silica molecular sieve (MCM-41) as supporting matrix and two rhodamine derivatives as chemosensors, respectively. These two composite sensing samples were characterized carefully by means of electron microscopy, mesoporous analysis, magnetic response, IR spectra and thermal stability analysis. Emission of these two composite sensing samples was found quenchable by nitrite ion, with limit of detection as low as 1.2 μM. Detailed analysis suggested that these chemosensors followed a static sensing mechanism towards nitrite ion through an additive reaction. These chemosensors could be recycled and recovered by sulphamic acid after nitrite ion sensing.

The fluoride anion (F−) sensing abilities of 1-hydroxyl-3,4,9,10-tetra (n-butoxyloxycarbonyl) perylene (probe 1) and 1-hydroxyl-mono-five-membered S-heterocyclic annulated tetra (n-butoxyloxycarbonyl) perylene (probe 2) were studied through visual detection experiments, UV-Vis, fluorescence, and 1H NMR titrations. The probes were sensitive and selective for distinguishing F− from other anions (Cl−, Br−, I−, SO4−, PF6−, H2PO4−, BF4−, ClO4−, OH−, CH3COO−, and HPO42−) through a change of UV-Vis and fluorescence spectra. The absorption and fluorescence emission properties of the probes arise from the intermolecular proton transfer (IPT) process between a hydrogen atom on the phenolic O position of probe and the F− anion. The sensing mechanism was supported by theoretical investigation. Moreover, probe-based test strips can conveniently detect F− without any additional equipment, and they can be used as fluorescent probes for monitoring F− in living cells.

Co9S8 can catalyze polysulfides conversion in Lithium sulfur batteries (LSBs) owing to its metallic nature and rich catalytic sites. However, its catalytic activity and chemical adsorption is not strong enough to suppress the shuttle effect of Lithium polysulfides (LiPS) under high sulfur loading. Herein, Phosphorous (P)-doped Co9S8 nanoparticle was synthesized and embedded into 3D Spongy carbon (SC) sheets as electrochemical catalyst for LSBs. Our Density functional theory (DFT) calculations and experimental results revealed that moderate P doping can modulate the electronic structure of Co9S8 and simultaneously improve its interaction with LiPS and promote LiPS conversion. When P-doped Co9S8 nanoparticles are in situ formed and homogeneously distributed on 3D spongy carbon sheet matrix, the resulting P-Co9S8@SC can ensure good exposure of their adsorption and catalytic sites. As a result, the LSB based on an optimized P-Co9S8@SC modified polypropylene separator exhibited excellent cycling stability (capacity decay of 0.05% per cycle over 900 cycles at 1 C) and high areal capacity (4.38 mAh cm−2 at 5.6 mg cm−2 sulfur loading at 0.1 C). Our work demonstrates that moderate heteroatom doping is a promising strategy to develop effective polysulfides catalysis.

The AC electrokinetic technology, such as AC electroosmosis, induced-charged electroosmosis, dielectrophoresis, etc., can precisely manipulate trace fluids and has been widely used in lab on a chip. However, the power supplies used in AC electrokinetic experiments are mostly function generators or other large-scare instruments, which is an obstacle to portability. Encouragingly, triboelectric nanogenerator (TENG) with the characteristics of portable, green, and simple structure is a potential opportunity for AC electrokinetic microfluidic operation. We have designed a self-powered AC electrokinetic microfluidic system based on vertical contact-separation mode TENG for the first time. The TENG, as a power supply, costs only 2 cents and maintains excellent output performance after millions of working cycles. Through the combination of TENG and microfluidic chip, this system successfully realizes AC electroosmotic flow and induced-charged electroosmotic flow in the microchannel and completes the effective mixing of two fluids at low frequencies (

Two novel fluorescence sensors (1 and 2) based on perylene tetra-(alkoxycarbonyl) derivative (PTAC) were designed and synthesized. The properties of sensors were detected by absorption, fluorescence spectra and electrochemical response. Test results indicated that the sensors had specific selectivity and high sensitivity for fluoride ion (F−) among the halide anions examined (F−, Cl−, Br− and I−). The absorption and fluorescence emission properties of the sensors arise from the intermolecular proton transfer (IPT) process between a hydrogen atom on the amide N position of sensor and the fluoride ion. Corresponding orbital electron distribution and molecular geometry configurations of the compounds were predicted by density functional theory (DFT). Moreover, sensor-based test strips can conveniently detect F− without any additional equipment. Incorporating S atom into perylene tetra esters 2 led to modified aromatic systems while retaining planarity and large conjugated π-bonds, and such molecular tailoring approach would be helpful for designing and synthesizing novel ratio metric fluorescent perylene chemosensors for F−.

In this work, a new asymmetrically five-membered O-heterocyclic annulated perylene diimide (O-PDI) has been synthesized. The compounds O-PDI and asymmetrically five-membered S-heterocyclic annulated perylene diimide (S-PDI) self-assembled into nanoneedle and nanosheet, respectively. Photophysical, electrochemical and thermal properties were investigated by UV–vis absorption, fluorescence, cyclic voltammetric, thermogravimetric and differential scanning calorimetry techniques. Optical, fluorescence, scanning and transmission electron microscopies were employed in the molecular self-assembly studies. Due to significant electronic coupling between their heteroatom/heterocycles and perylene diimide (PDI) cores, the intermolecular π-π actions are neglectable, providing high luminescence efficiency. At the same time, the space between perylene chromophores is still very short (3.3 A for O-PDI and 3.23 A for S-PDI), which is favorable for the hopping transportation of charge carrier from one molecule to a neighboring one. These compounds could be candidate materials for acquiring well defined organic nanostructures with both excellent charge-transporting and good light-emitting capabilities.

We present a flexible and noninvasive approach for efficient continuous micromixing and microreaction based on direct current-induced thermal buoyancy convection in a single microfluidic unit. Theoretically, microfluids in this microsystem are unevenly heated by powering the asymmetrically arranged microheater. The thermal buoyancy convection is then formed to induce microvortices that cause effective fluidic interface disturbance, thereby promoting the diffusion and convective mass transfer. The temperature distribution and the convection flow in the microchip are first characterized and studied, which can be flexibly adjusted by changing the DC voltage. Then the mixing performance of the presented method is validated by joint numerical and experimental analyses. Specifically, at U = 7 V, the mixing efficiencies are higher than 90% as the flow rate is lower than Qv= 600 nL/s. So high-quality chemical or biochemical reactions needing both suitable heating and efficient mixing can be achieved using this method. Finally, as one example, we use this method to synthesize nano-sized cuprous oxide (Cu2O) particles by effectively mixing the Benedict’s solution and glucose buffer. Remarkably, the particle size can be tuned by changing the voltage and the concentration of Benedict’s solution. Therefore, this micromixer can be attractive for diverse applications needing homogeneous sample mixtures.

The wiped film molecular distillation system is a complex multivariable strong coupling system in which the temperature and vacuum in the evaporator are coupled. In this paper, based on the previous experimental data, the mathematical model of temperature and vacuum is established by the method of system identification. Secondly, the system model matrix is designed according to the actual decoupling system structure, the controller matrix is decoupled and the controller of the system is designed by the expected dynamic method to construct the decoupling control model. Finally, compared with the traditional PID controller, the simulation results show that the system with the expected dynamic method has faster response time, less overshoot and stronger robustness.

Bacillus anthracis spores have a unique biomarker of calcium dipicolinate (CaDPA). In this work, we reported a composite nanostructure for the optical sensing of DPA, with Eu (III)-doped metal-organic framework (MOF) as supporting lattice, a rhodamine-derived dye as sensing probe, respectively. By means of XRD, IR, TGA and photophysical analysis, this composite structure was carefully discussed. It was found that rhodamine absorption and emission were enhanced by DPA, while Eu emission was quenched by DPA. As a consequence, two sensing skills were observed from this composite structure, which are colorimetric sensing based on absorption spectra and ratiometric fluorescent sensing based on emission spectra. Linear sensing response was observed for both sensing channels with a warning signal at DPA concentration higher than 140 μM. Good selectivity was confirmed with a low LOD value of 0.52 μM. The sensing mechanism was revealed as the combination of emission turn-on effect triggered by DPA-released protons and emission turn-off effect originated from electron-transfer from EuBTC to DPA. This composite structure showed its advantage of naked eye detection and two sensing skills with linear response.

Five arc-shaped gaps were designed on the bipolar electrode to actuate alternately opposite-direction asymmetrical induced-charge electro-osmosis (AICEO) vortices, and we developed a microfluidic device using such asymmetrical vortices to realize particle separation. When the buoyancy force dominates in the vertical direction, particles stay at the channel bottom, experiencing a left deflection under the vortices in the convex arc areas. In contrast, when the levitation force induced by AICEO vortices overcomes the buoyancy force, particles are elevated to a high level and captured by right vortices, undergoing a right deflection under the vortices in the concave arc areas. Moreover, when particles pass through the concave or convex arc areas every time, their right or left deflections are enlarged gradually and the separation becomes more complete. Remarkably, as the light/small particles at low voltage, heavy/large particles can be elevated to a new high level and undergo right deflection by increasing the voltage. We first explicitly proved the separation principle and analyzed numerically its capability in density- and size-based separation. Depending on the study of the voltage-dependent AICEO characterization of 4 μm silica and 4 μm PMMA particles, we experimentally verified the feasibility of our device in density-based separation. According to the investigation of sensitivity to particle size, we separated multi-sized yeast cells to confirm the capability of our device in size-based separation. Finally, we extracted yeast cells from impeding particles, obtaining 96% purity. Additionally, we designed a 500 μm distance between the focusing and separation region to circumvent the problems caused by electric-field interaction. Our AICEO-based separation method holds potential to serve as a useful tool in transesterification of microalgal lipids to biodiesel and solar cell processing because of its outstanding advantages, such as gentle conditions, contact-free separation, high-sensitivity and high-efficiency separation capability.

Microfluid mixing is an essential process in chemical analysis, drug test, and nanoparticle synthesis. Induced charge electro-osmosis (ICEO) has good capability in microfluid mixing for its reconfigurable vortex profile. We found experimentally ICEO transverse flow induced by the asymmetrical driving electrode has a good performance in disturbing the interface of two fluids. Encouraged by these aspects, we proposed a micromixer using ICEO transverse flows actuated by the asymmetrical driving electrode sequence to mix microfluids. We established a simulation model to investigate the evolution of the interface and demonstrate the work principle of this method. Moreover, we numerically explored the effects of device structure, and electrolyte characteristics on the capability of micromixer. Finally, we validated this method experimentally, and studied the effects of voltage intensity, frequency and flow rate on the mixing capability, obtaining mixing efficiency exceeding 94%. This method is a potential alternative in various microfluidic and lab-on-a-chip applications.

Efficient granular sample manipulation is crucial for various microfluidic-based applications such as material synthesis and drug delivery. Herein we present a novel method to efficiently manipulate microbeads and droplets using the combined thermal buoyancy convection and temperature-enhanced rotating induced-charge electroosmotic flow. Within the granular fluid, a pair of counter-rotating microvortices is formed above the floating electrode, leading to the formation of a flow stagnation region at the bottom center. Granular samples then can be effectively transported to this region by the Stokes drag, and the concentration performance can be flexibly manipulated by adjusting the energization strategies of the chip. The contributions of fluid convection, dielectrophoresis, thermophoresis, and gravity force to particle migration are first studied and compared, proving that the convection flow and gravity force are mainly responsible for particle migration and deposition respectively. Then the systematic enriching experiments of 4-μm silica particles demonstrate that the particle migration velocity can be highly improved by the combined thermal-electrical field. Finally, the effective concentration of nanocopper particles and the assembly of oil-in-water/water-in-oil-in-water droplets indicate that this approach is capable of manipulating diverse granular samples. Therefore, this strategy can be attractive for lots of microfluidic-based applications because of its high efficiency and simplicity.

Vortex-based separation is a promising method in particle-particle separation and has only been demonstrated theoretically some years ago. To date, a continuous-flow separation device based on vortices has not been conceived because many known vortices were either unstable or controlling them lacked precision. Electro-convection from induced charge electro-osmosis (ICEO) has advantages, such as adjustable flow profiles, long-range actuation, and long-lived vortices, and offers an alternative means of particle separation. We found though a different ICEO focusing behaviour of particles whereby particles were trapped and concentrated in two vortex cores. Encouraged by these features of ICEO vortices, we proposed a direct method for particle separation in continuous flow. In various experiments, we first characterized the ICEO-induced focusing performances of various kinds of particle samples in a straight channel embedded with an individual central bipolar electrode, presenting a justifiable explanation. Second, the combined dependences of ICEO particle separation on the sample size and mass density were investigated. Third, an application to cell purification was performed in which we obtained a purity surpassing 98%. Finally, we investigated the ICEO characteristics of nanoparticles, exploiting our method in isolating nanoscale objects by separating 500 nm and 5 μm polystyrene beads, gaining clear separation. Certain features of this method, such as having ease of operation, simple structure, and continuous flow, and being prefocusing free and physical property-based, indicate its good potential in tackling environmental monitoring, cell sorting, chemical analysis, isolation of uniform-sized graphene and transesterification of micro-algal lipids to biodiesel.

Supplemental material, Supplementary_Data for Synthesis and properties of bay unilaterally extended and mono-substituted perylene diimides by Fengxia Zhang, Xianqiang Huang, Xiaofeng Wei, Huixue Ren, Tianyi Jiang, Xuemei Li, Junsen Wu and Yongshan Ma in Journal of Chemical Research

Monodisperse micro-sized liquid metal droplets have received considerable attention for developing flexible electronics, microfluidics actuators and reconfigurable devices. Herein we report an innovative and efficient strategy for large-scale preparation of Galinstan liquid metal microdroplets with controllable sizes using a micro-needle induced glass capillary microfluidic device. By inserting a stainless steel micro-needle into the inner liquid metal phase in the glass capillary, the hydrodynamic instability of the liquid metal stream is significantly suppressed to guarantee steady fluid flow before the liquid metal is pinched off by the outer phase flow, giving rise to a stable generation of monodisperse liquid metal microdroplets. The microdroplet size dependence on the flow ratio of the continuous and dispersed-phase is investigated experimentally. A theoretical framework based on the Plateau–Rayleigh instability is proposed to explain the advantage of the micro-needle induced strategy. This strategy has great potential for the generation of high interfacial tension liquid metal emulsions.

Summary It is advantageous for rhizosphere-dwelling microorganisms to utilize organic acids such as lactate. Pseudomonas putida KT2440 is one of the most widely studied rhizosphere-dwelling model organisms. The P. putida KT2440 genome contains an NAD-dependent d-lactate dehydrogenase encoding gene, but mutation of this gene does not play a role in d-lactate utilization. Instead, it was found that d-lactate utilization in P. putida KT2440 proceeds via a multidomain NAD-independent d-lactate dehydrogenase with a C-terminal domain containing several Fe-S cluster-binding motifs (Fe-S d-iLDH) and glycolate oxidase, which is widely distributed in various microorganisms. Both Fe-S d-iLDH and glycolate oxidase were identified to be membrane-bound proteins. Neither Fe-S d-iLDH nor glycolate oxidase is constitutively expressed but both of them can be induced by either enantiomer of lactate in P. putida KT2440. This study shows a case in which an environmental microbe contains two types of enzymes specific for d-lactate utilization.

A fluorescent pH-sensitive probe, 1-hydroxyl-3,4;9,10-tetra(n-butoxyloxycarbonyl)perylene (HPTBAC), was synthesized and used for pH sensing in living cells. The probe exhibits fluorescence emission characteristics with a pKa value of 7.9 and linear response to the very important pH range of 6.7–8.9. We designed a probe for binding the O− of hydroxyl in the perylene skeleton with H+ to possess the probing capability for detection in the acid to weak base pH range. The pH sensitivity is introduced via the O− moiety upon either protonation or deprotonation. In the deprotonation form, HPTBAC exhibits very weak emission due to strong electron-donating groups of O−. HPTBAC was successfully applied as a high-performance fluorochrome for living A549 cell (human lung cancer) and E. coli cell imaging. The results demonstrate that as a pH probe, HPTBAC is a good candidate for monitoring pH fluctuations in living cells.

Molybdenum disulfide (MoS2) is a promising anode material for sodium ion battery. Nevertheless, the semi-conductive feature and closely stacked nanostructure hinder its application. Moreover, the uncontrolled geometric structure and loose combination with high-conductive matrix lead to a limited Na+ diffusion path and easy-destroyed structure. Here, a strongly-combined MoS2/rGO nanosheet structure is realized by ionic liquid induced layer-by-layer self-assembly approach. The ionic liquid works well as bi-functional assisted solvent to induce the uniform growth of MoS2 on rGO layers and to maintain the large-scale morphology of rGO nanosheet. The enlarged interlayer distance between S–Mo–S adjacent planes facilitates the fast Na+ transport. The well-maintained rGO layer affords favorable tolerance to the volume change of MoS2 and increases the conductivity as well. Density function theory calculations demonstrate that the enlarged interlayer reduces the diffusion energy barriers of Na+ and accelerates the reaction kinetics. Benefitting from the strong bonding between few-layered MoS2 nanoflake and well-maintained 2D rGO nanosheet, the MoS2/rGO composite exhibits a high specific capacity (581.7 mA h g−1 after 100 cycles at 100 mA g−1), remarkable rate capability (309.2 mA h g−1 at 12.8 A g−1) and excellent cycling stability (263.2 mA h g−1 after 300 cycles at 3 A g−1).

The construction of organic–inorganic hybrids is one of the important ways to improve performances of photocatalysts. In this study, perylene tetracarboxylic tetra (n-butyl) ester loaded titanium dioxide (PTTE-B/TiO2) nanocomposite was successfully synthesized by hydrothermal method. The catalyst was characterized by XRD, DRS, XPS, Photoluminescence spectroscopy (PL) and BET. FT-IR and XPS analyses revealed the presence of Ti[Formula: see text]O bond in the interfaces between TiO2 and PTTE-B. The photoluminescence intensity of PTTE-B/TiO2 was decreased compared to TiO2, which indicated a suppression of electron–hole recombination by the loaded PTTE-B nanoparticles. The photocatalytic activity of PTTE-B/TiO2 nanocomposite for degradation of EBT using visible light was higher than that of prepared TiO2 or TiO2-P25. The detection of radical scavengers confirmed that h[Formula: see text] and [Formula: see text] were the main active substances for Eriochrome Black T (EBT, an azo dye) degradation. The Ti[Formula: see text]O bond acted as a short and fast channel for photogenerated charge carriers to migrate from PTTE-B to TiO2. Furthermore, PTTE-B/TiO2 was found to be stable and reusable.

In this study, an eccentric magnetic microcapsule is reported for on-demand transportation, release, and evacuation in a micro-fabrication fluidic network. Using a droplet-based microfluidic technology, monodisperse magnetic polydimethylsiloxane (PDMS) core-shell microcapsules with a small eccentric ferrofluid core and a big aqueous core are fabricated from templates of dual-cored water-in-oil-in-water ((W1+W2)/O/W) double-emulsion droplets. The eccentric ferrofluid core enables the microcapsule to have flexible magnetic responsibility and orientation property, and the aqueous core can realize the encapsulation and release of nanoliter-scale encapsulants. Each microcapsule can be magnetic-guided by an external magnetic field to travel in microchannels along a designated route, and thus transport the encapsulated cargo (the aqueous core) to the targeted region. Then, the promptly shell rupture of the microcapsule due to the action of a time-averaged electrical stress from Maxwell-Wagner structural polarization in an externally-imposed alternating-current (AC) electric field allows the release of cargo into the region. Moreover, the empty microcapsule after release of the aqueous core can be magnetic-guided to evacuate from the device. Finally, to prove the practical utility of the eccentric magnetic microcapsule for on-demand transportation and release of nanoliter-scale encapsulant, this microcapsule is used to targeted convey fluorescent nanoparticles, which not only can serve as tracers to show the release of the aqueous core, but also can be cargoes themselves for bioimaging, sensing, and so on.

Crumpled graphene oxide (CGO) balls are new 3D applied materials, which present good potential in the development of energy storage and conversion devices for the advantages of high surface areas and resistant to aggregation. Utilizing ready-made CGO balls with defined sizes to synthesize desired materials or modify existing components, if achieved, we may make the functions and properties of the final products more controllable and programmable. However, acquiring uniform-size CGO particles still remains under challenge now, because uniform-size pristine graphene oxide is difficult to obtain and the size of CGO balls is sensitive to many parameters during the synthesis. An alternative potential solution, classifying the synthetized CGO balls to obtain uniform-size CGO balls may ingeniously circumvent above tricky issue. Here we designed tilted-angle ridge floating electrode sequence (TARFES) to actuate cyclical asymmetrical ICEO (AICEO) vortices to achieve particle separation and augment the throughput capability (105 particles/h), overcoming the limitation of existing vortex-based separation criteria. We firstly conducted simulations to identify the optimum configuration of TARFES. According to spatial features of cyclic AICEO vortices, two separation modes were developed. We separated silica and polymethyl methacrylate (PMMA) microbeads to validate the capability of the first separation mode, and studied the effects of voltage and flow speed on the separation results, obtaining 97.3% separation efficiency. We then separated PMMA microbeads and yeast cells with 93.1% separation efficiency to evidence the second separation mode. Also, we accomplished the simultaneous separation of multiple particles. Depending on characterization of CGO balls, the second separation mode was successfully engineered to realize size fractionation of CGO balls in continuous flow, yielding clear separation. Finally, we also modulated the voltage input to isolate nanoscale CGO balls from the background. This operative separation technique offers a unique route to acquire uniform-size CGO balls with potential applications in the fabrications of batteries and ultracapacitors.

The gallium-based eutectic liquid metal alloys exhibit unique properties of deformability, excellent electrical conductivity and low vapour pressure. The liquid metal-based circuits&rsquo, element or actuator have drawn considerable attention in stretchable electronics and microelectromechanical (MEMS) actuators. Yet, the motion of the liquid metal within the electrolyte needs to be precisely regulated to satisfy application requirements. Herein, we investigated the locomotion of liquid metal within the alkaline aqueous solution under electrostatic actuation. The relationship between the travelling speed of the liquid metal slug and the relative influential parameters, such as the voltage amplitude and frequencies of the applied electric field, electrolyte concentration, electrodes distance and the liquid metal volume, were experimentally characterized. A travelling speed up to 20.33 mm/s was obtained at the applied voltage of 4 Vpp at 150 Hz at 6 V DC offset. Finally, the frequency-dependent liquid metal marble movements were demonstrated, namely oscillation and forward locomotion while oscillating. The oscillation frequency was determined by the frequency of the applied alternate current (AC) signal. The remarkable transportation and oscillating characteristic of the liquid metal marble under the electrostatic actuation may present potentials towards the development of flexible electronics and reconfigurable structures.

A two-phase flow axisymmetric numerical model was proposed to understand liquid metal droplet formation in a co-flowing capillary microfluidics device based on a phase field model. The droplet detachment processes were observed in the experiment and are in good agreement with the simulation method. The effects of the viscosities and flowrates of the continuous phase fluid, interfacial tension as well as the wetting property of the metallic needle against the bulk liquid metal on the droplet formation and production rate were numerically investigated. It was found that the droplet diameter decreased with the increment of the viscosities and flowrates of the outer phase carrier fluid. The dispersed phase fluid with high interfacial tension tended to prolong the time for equilibrium between the viscous drag force and interfacial tension on the liquid&ndash, liquid fluid surface, delaying the droplet to be pinched off from the capillary orifice and causing large droplet diameter. Finally, the wetting performance of the metallic needle against the liquid metal was explored. The result indicate that the droplet diameter became less dependent on the contact angle while the size distribution of the liquid metal droplet was affected by their wetting performance. A more hydrophilic wetting performance were expected to prepare liquid metal droplet with more monodispersity. The numerical model and simulation results provide the feasibility of predicting the droplet formation with a high surface tension in a glass capillary microfluidic device.

A unique platform to fabricate tunable micropatterns at an electrically floating electrode has been developed via an enhanced combination of dielectrophoresis (DEP) and alternating current electrothermal (ACET) processes. The design of the platform uses two pairs of driving electrodes to generate a tunable electric field at a floating electrode, which in turn allows for the formation of patterned cells and fluids with desired features. By regulating the input configuration of the ac signals, yeast cells can be either patterned at the field stagnant region by a synergistic combination of negative DEP and ACET flow, or partially captured at the electrode edges subjected to a strong positive DEP, to form varying cell patterns. Additionally, nanoparticles were used to characterize the ACET-based flow pattern formation. Furthermore, the patterns were successfully exploited as an electrokinetic actuator to actuate continuous droplet switching, fluid mixing and microreactions. Implementing the simultaneous nanoparticle synthesis and guiding demonstrated that the combined field pattern is capable of manipulating both particulate samples and fluids. The proposed micropatterning technique may provide new insights for sample manipulation, on-chip function development and integration with other analytical components (i.e., biochemical sensors, chemical detectors, cell culture bioreactors) owing to a facile operation, easy integration and multifunctionality.

Metal sulfides (MS) have been widely explored in lithium-sulfur batteries (LSB) owing to their stronger affinity with lithium polysulfide species (LPS) than carbon materials and higher electronic conductivity compared with metal oxides. However, practical application of MS based sulfur cathodes is hindered by a slow conversion of sulfur species due to limited catalytic effect of MS for redox reactions of sulfur, and by the absence of a continuous conducting network in the cathode. To address these issues, we herein report the design and fabrication of a heterostuctured Co3S4/MnS nanotube array grown on carbon cloth (CC@CMS-NA) as a catalytic sulfur host for high performance LSB. According to the theoretical calculations and electrochemical test, Mn dopants can tune the electronic structure of Co3S4 to adsorb soluble LPS more effectively and engineer a catalytic heterogeneous surface to facilitate charge transport and enhance the conversion kinetics of sulfur species. Meanwhile, the 3D array structure avoids “dead” sites caused by the use of binder and conductive additive, and also provides rapid electron transport path. As a result, the CC@CMS-NA based sulfur cathodes with 3.2 mg cm−2 sulfur loading exhibits an excellent cycle performance at a current density of 2.67 mA cm−2 (95% retention of initial specific capacity after 200 cycles, namely 0.02% decay per cycle). Our work demonstrates that reasonable construction of heterogeneous structures is a promising strategy to improve the performance of MS based LSB.

The wiped film molecular distillation system has the characteristics of multivariable, strong coupling, nonlinearity and large hysteresis. Current modeling and control methods are difficult to achieve the desired results. In order to stabilize production, the online sequential extreme learning machine soft measurement model driven by data is constructed by analyzing the auxiliary parameter variables. The dual heuristic dynamic programming learning control was used to optimize for the molecular distillation system. Comparing with traditional back propagation neural network modeling. The simulation experiments are performed to verify the effectiveness and advantage of dual heuristic dynamic programming learning control with online sequential extreme learning machine soft measurement model.

Soil contaminated with Cd and Pb has caused sharp decrease of cultivatable soil and has been attracting increasing attention. Biosurfactants are efficient in solving the problem. However, little information is available about the influence of sophorolipids (SLs) on the remediation of Cd- or Pb-contaminated soil. The sophorolipids produced by Starmerella bombicola CGMCC 1576 were used to study the effects of Cd and Pb removal in batch soil washing from artificially contaminated soil. The removal efficiency of crude total SLs was better than both distilled water and synthetic surfactants. Furthermore, 83.6% of Cd and 44.8% of Pb were removed by 8% crude acidic SLs. Acidic SLs with high water solubility were more effective than lactonic SLs in enhancing remediation of heavy metal-contaminated soils. The complexation of Cd with the free carboxyl group of the acidic SLs was observed by Fourier-transform infrared spectroscopy study, and this complexation was effective in heavy metal removal from the soil. The fermentation broth of S. bombicola, without further preparation, removed 95% of Cd and 52% of Pb. These results suggested that SLs produced by S. bombicola could function as potential bioremediation agents for heavy metal-contaminated soil.

Soil contaminated with Cd and Pb has caused sharp decrease of cultivatable soil and has been attracting increasing attention. Biosurfactants are efficient in solving the problem. However, little information is available about the influence of sophorolipids (SLs) on the remediation of Cd- or Pb-contaminated soil. The sophorolipids produced by Starmerella bombicola CGMCC 1576 were used to study the effects of Cd and Pb removal in batch soil washing from artificially contaminated soil. The removal efficiency of crude total SLs was better than both distilled water and synthetic surfactants. Furthermore, 83.6% of Cd and 44.8% of Pb were removed by 8% crude acidic SLs. Acidic SLs with high water solubility were more effective than lactonic SLs in enhancing remediation of heavy metal-contaminated soils. The complexation of Cd with the free carboxyl group of the acidic SLs was observed by Fourier-transform infrared spectroscopy study, and this complexation was effective in heavy metal removal from the soil. The fermentation broth of S. bombicola, without further preparation, removed 95% of Cd and 52% of Pb. These results suggested that SLs produced by S. bombicola could function as potential bioremediation agents for heavy metal-contaminated soil.

In this study, we make use of the AC field-effect flow control on induced-charge electroosmosis (ICEO), to develop an electrokinetic micromixer with 3D electrode layouts, greatly enhancing the device performance compared to its 2D counterpart of coplanar metal strips. A biased AC voltage wave applied to the central gate terminal, i.e., AC field-effect control, endows flow field-effect-transistor of ICEO the capability to produce arbitrary symmetry breaking in the transverse electrokinetic vortex flow pattern, which makes it fascinating for microfluidic mixing. Using the Debye-Huckel approximation, a mathematical model is established to test the feasibility of the new device design in stirring nanoparticle samples carried by co-flowing laminar streams. The effect of various experimental parameters on constructing a viable micromixer is investigated, and an integrated microdevice with a series of gate electrode bars disposed along the centerline of the channel bottom surface is proposed for realizing high-flux mixing. Our physical demonstration on field-effect nonlinear electroosmosis control in 3D electrode configurations provides useful guidelines for electroconvective manipulation of nanoscale objects in modern microfluidic systems.

Induced-charge electroosmosis (ICEO) has attracted tremendous popularity for driving fluid motion from the microfluidic community since the last decade, while less attention has been paid to ICEO-based nanoparticle manipulation. We propose herein a unique concept of hybrid electroosmotic kinetics (HEK) in terms of bi-phase ICEO (BICEO) actuated in a four-terminal spiral electrode array, for effective electrokinetic enrichment of fluorescent polystyrene nanoparticles on ideally polarizable metal strips. First, by alternating the applied AC voltage waves between consecutive discrete terminals, the flow stagnation lines where the sample nanoparticles aggregate can be switched in time between two different distribution modes. Second, we innovatively introduce the idea of AC field-effect flow control on BICEO; by altering the combination of gating voltage sequence, not only the number of circulative particle trapping lines is doubled, but the collecting locations can be flexibly reconfigured as well. Third, hydrodynamic streaming of DC-biased BICEO is tested in our device design, wherein the global linear electroosmosis dominates BICEO contributed from both AC and DC components, resulting in a reduction of particle enrichment area, while with a sharp increase in sample transport speed inside the bulk phase. The flow field associated with HEK is predicted using a linear asymptotic analysis under Debye-Huckel limit, with the simulation results in qualitative agreement with in-lab observations of nanoparticle trapping by exploiting a series of improved ICEO techniques. This work provides an affordable and field-deployable platform for real-time nanoparticle trapping in the context of dilute electrolyte.

Complex, realistic scenarios in training simulations can benefit from good control of large numbers of simulation entities. However, training simulations typically focus on simulation physics and graphics over the intelligence required to control large numbers of entities. Real-Time Strategy games, on the other hand, have evolved to make tradeoffs between the AI needed and human interaction required to control hundreds of entities in complex tactical skirmishes. Borrowing from work in real-time strategy games, this paper attacks the problem of controlling groups of heterogenous entities in training simulations by using a genetic algorithm to evolve control algorithm parameters that maximize damage done and minimize damage received during skirmishes in a real-time strategy game-like simulation. Results show the emergence of complex, coordinated behavior among groups of simulated entities. Evolved behavior quality seems to be relatively independent of the underlying physics model but depends on the initial dispositions of entities in the simulation. We can get over this dependence and evolve more robust high performance behaviors by evaluating fitness in several different scenarios with different initial dispositions. We believe these preliminary results indicate the viability of our approach for generating robust, high performance behaviors for controlling swarms of entities in training simulations to enable more complex, realistic training scenarios.

Perylene diimides (PDIs) are one class of the most explored organic fluorescent materials due to their high luminescence efficiency, optoelectronic properties, and ready to form well-tailored supramolecular structures. However, heavy aggregation caused quenching (ACQ) effect in solid state has greatly limited their potential applications. We have easily solved this problem by chemical modification of the PDI core with only phenoxy moietie at one of the bay position. In this paper, we report two perylene bisimides with small rigid substituents, 1- phenol -N, N’-dicyclohexyl perylene-3,4,9,10-tetracarboxylic diimide (PDI 1) and 1- p-chlorophenol-N, N’-dicyclohexyl perylene-3,4,9,10-tetracarboxylic diimide (PDI 2) possess both well defined organic nanostructures and high fluorescence quantum yield in the solid state. In contrast, 1-propanol-N, N’-dicyclohexyl perylene-3,4,9,10-tetracarboxylic diimide (PDI 3) bearing a straight chain only shown weak orange fluorescence. In addition, morphological inspection demonstrated that PDI 3 molecules easily form well-organized microstructures despite the linkage of the PDI core with a straight chain. The present strategy could provide a generic route towards novel and advanced fluorescent materials and these materials may find various applications in high-tech fields.

We present herein a novel method of bipolar field-effect control on DC electroosmosis (DCEO) from a physical point of view, in the context of an intelligent and robust operation tool for stratified laminar streams in microscale systems. In this unique design of the DC flow field-effect-transistor (DC-FFET), a pair of face-to-face external gate terminals are imposed with opposite gate-voltage polarities. Diffuse-charge dynamics induces heteropolar Debye screening charge within the diffuse double layer adjacent to the face-to-face oppositely-polarized gates, respectively. A background electric field is applied across the source-drain terminal and forces the face-to-face counterionic charge of reversed polarities into induced-charge electroosmotic (ICEO) vortex flow in the lateral direction. The chaotic turbulence of the transverse ICEO whirlpool interacts actively with the conventional plug flow of DCEO, giving rise to twisted streamlines for simultaneous DCEO pumping and ICEO mixing of fluid samples along the channel length direction. A mathematical model in thin-layer approximation and the low-voltage limit is subsequently established to test the feasibility of the bipolar DC-FFET configuration in electrokinetic manipulation of fluids at the micrometer dimension. According to our simulation analysis, an integrated device design with two sets of side-by-side, but upside-down gate electrode pair exhibits outstanding performance in electroconvective pumping and mixing even without any externally-applied pressure difference. Moreover, a paradigm of a microdevice for fully electrokinetics-driven analyte treatment is established with an array of reversed bipolar gate-terminal pairs arranged on top of the dielectric membrane along the channel length direction, from which we can obtain almost a perfect liquid mixture by using a smaller magnitude of gate voltages for causing less detrimental effects at a small Dukhin number. Sustained by theoretical analysis, our physical demonstration on bipolar field-effect flow control for the microfluidic device of dual functionalities in simultaneous electroconvective pumping and mixing holds great potential in the development of fully-automated liquid-phase actuators in modern microfluidic systems.

Around one-fourth of the Komagataella phaffii genes encode hypothetical proteins with unknown functions. However, lack of powerful tools for genetic screening in K. phaffii significantly limits the functional analysis of these unknown genes. Transposon mutagenesis has been utilized as an insertional mutagenesis tool in many other organisms and would be extremely valuable if it could be applied in K. phaffii. In this study, we investigated in K. phaffii the transposition activity and efficiency of piggyBac (PB) transposon, a DNA transposon from the cabbage looper moth Trichoplusia ni through the integrated-plasmid system. We also designed a binary-plasmid system which could generate stable mutants. Finally we evaluated the quality of this mutagenesis system by a simple screening for functional genes involved in K. phaffii carbon catabolite repression. Our results demonstrate that PB-mediated mutagenesis could be a feasible and useful tool for functional gene screening in K. phaffii.

d -Lactate was identified as one of the few available organic acids that supported the growth of Gluconobacter oxydans 621H in this study. Interestingly, the strain used d -lactate as an energy source but not as a carbon source, unlike other lactate-utilizing bacteria. The enzymatic basis for the growth of G. oxydans 621H on d -lactate was therefore investigated. Although two putative NAD-independent d -lactate dehydrogenases, GOX1253 and GOX2071, were capable of oxidizing d -lactate, GOX1253 was the only enzyme able to support the d -lactate-driven growth of the strain. GOX1253 was characterized as a membrane-bound dehydrogenase with high activity toward d -lactate, while GOX2071 was characterized as a soluble oxidase with broad substrate specificity toward d -2-hydroxy acids. The latter used molecular oxygen as a direct electron acceptor, a feature that has not been reported previously in d -lactate-oxidizing enzymes. This study not only clarifies the mechanism for the growth of G. oxydans on d -lactate, but also provides new insights for applications of the important industrial microbe and the novel d -lactate oxidase.

A fluorescent pH probe, N,N'-bi( l-phenylalanine amine)-perylene-3,4;9,10-dicarboxylic diimide (PDCDA) was synthesized and used for pH sensing in living cells. A significant fluorescence intensity change was observed over a pH range from 7.0 to 4.0. Electrostatic potential maps (MEP) suggested that the electronic repulsion between PDCDAs was increased by the high negative electrostatic potential which resulted in a high water solubility of PDCDA. PDCDA was successfully applied as a high-performance fluorochrome for living HeLa cell imaging. The results demonstrate that the probe PDCDA is a good candidate for monitoring pH fluctuations in living cells with good water solubility, low cytotoxicity, high fluorescence quantum yield and photostability.

We prepared amino acid functionalized water-soluble perylene diimides: N,N′-bi(L-glutamic acid)-perylene-3,4;9,10-dicarboxylic diimide (1), N,N′-bi(L-phenylalanine acid)-perylene-3,4;9,10-dicarboxylic diimide (2), N,N′-bi(L-glutamic amine)-perylene-3,4;9,10-dicarboxylic diimide (3) and N,N′-bi(L-phenylalanine amine)-perylene-3,4;9,10-dicarboxylic diimide (4). The structures of 3 and 4 were confirmed by 1H NMR, FT-IR and MS. The maximal absorption bands of compound 1 and 2 in concentrated sulfuric acid were red-shifted for about 48 and 74 nm, respectively, compared with that of Perylene-3,4,9,10-tetracarboxylic acid dianhydride (PTCDA). Nearly no fluorescence was observed for compounds 1 and 2 in water, while compounds 3 and 4 were significantly water-soluble and had very high fluorescent quantum. The mechanism of the optical properties change was discussed, and the π-π stacking caused by H+ led to the changes of fluorescence spectrum and absorption spectrum. The calculated molecular orbital energies and the frontier molecular orbital maps of compounds 1–2 based on density function theory (DFT) calculations were reported. Owing to the high water-soluble, the perylene derivatives 3 and 4 were successfully applied as high-performance fluorochromes for living hela cells imaging.

The ability of Microlunatus phosphovorus to accumulate large amounts of polyphosphate (Poly-P) plays an important role in removing soluble phosphorus from wastewater. Strain JN459, isolated from a sewage system, was previously demonstrated to be Microlunatus phosphovorus. In this study, we analyzed the phosphorus-accumulating and phosphorus-releasing characteristics of strain JN459. Our analyses indicate that strain JN459 accumulates Poly-P under aerobic conditions but releases phosphorus under anaerobic conditions. To determine the mechanisms underlying Poly-P metabolism in strain JN459, we compared transcriptional profiles under aerobic and anaerobic conditions. Significant differences were detected in the expression levels of genes associated with Poly-P metabolism between aerobic and anaerobic conditions, including ppk (MLP_47700, MLP_50300 and MLP_05750), ppgk (MLP_05430 and MLP_26610), ppx (MLP_44770), pap (MLP_23310) and ppnk (MLP_17420). The high expression of polyphosphate glucokinase (MLP_05430) and polyphosphate/ATP-dependent NAD kinase (MLP_17420) indicated that both of them might be responsible for utilizing Poly-P as the energy resource for growth under anaerobic conditions. These findings enhance our understanding of phosphate metabolism in a major bacterial species involved in wastewater phosphorus reduction.

Enterobacter cloacae strain R11 is a multidrug-resistant bacterium isolated from sewage water near a swine feedlot in China. Strain R11 can survive in medium containing up to 192 μg/mL polymyxin E, indicating a tolerance for this antibiotic that is significantly higher than that reported for other gram-negative bacteria. In this study, conjugation experiments showed that partial polymyxin E resistance could be transferred from strain R11 to Escherichia coli strain 25922, revealing that some genes related to polymyxin E resistance are plasmid-based. The complete genome sequence of this strain was determined, yielding a total of 4 993 008 bp (G+C content, 53.15%) and 4908 genes for the circular chromosome and 4 circular plasmids. Genome analysis revealed a total of 73 putative antibiotic resistance genes, including several polymyxin E resistance genes and genes potentially involved in multidrug resistance. These data provide insights into the genetic basis of the polymyxin E resistance and multidrug resistance of E. cloacae.

We attack the problem of evolving high performance micro behaviors in 3D RTS-game-like simulations. Prior work had shown the potential for the Meta-Search approach to evolve high performance micro for RTS games like StarCraft. We extend this work by moving to 3D and by moving to more realistic physics for simulating the movement of entities in our RTS-game-like simulation. We compare the evolved micro performance of our entities with different physics models of motion on the same scenarios against identical opponent units in a 3D RTS simulation. Results show that our genetic algorithm approach works to reliably evolve high quality 3D micro behaviors for entities independent of the physics model used. Furthermore, experiments show that the entity's acceleration has more of an effect on performance than rotation speed. Our work provides evidence for the generalizability of an evolutionary approach to generating complex behavior for 3D RTS games, training simulations, and real-world unmanned vehicles.

Bacterial membrane-associated NAD-independent d -lactate dehydrogenase (Fe-S d -iLDH) oxidizes d -lactate into pyruvate. A sequence analysis of the enzyme reveals that it contains an Fe-S oxidoreductase domain in addition to a flavin adenine dinucleotide (FAD)-containing dehydrogenase domain, which differs from other typical d -iLDHs. Fe-S d -iLDH from Pseudomonas putida KT2440 was purified as a His-tagged protein and characterized in detail. This monomeric enzyme exhibited activities with l -lactate and several d -2-hydroxyacids. Quinone was shown to be the preferred electron acceptor of the enzyme. The two domains of the enzyme were then heterologously expressed and purified separately. The Fe-S cluster-binding motifs predicted by sequence alignment were preliminarily verified by site-directed mutagenesis of the Fe-S oxidoreductase domain. The FAD-containing dehydrogenase domain retained 2-hydroxyacid-oxidizing activity, although it decreased compared to the full Fe-S d -iLDH. Compared to the intact enzyme, the FAD-containing dehydrogenase domain showed increased catalytic efficiency with cytochrome c as the electron acceptor, but it completely lost the ability to use coenzyme Q 10 . Additionally, the FAD-containing dehydrogenase domain was no longer associated with the cell membrane, and it could not support the utilization of d -lactate as a carbon source. Based on the results obtained, we conclude that the Fe-S oxidoreductase domain functions as an electron transfer component to facilitate the utilization of quinone as an electron acceptor by Fe-S d -iLDH, and it helps the enzyme associate with the cell membrane. These functions make the Fe-S oxidoreductase domain crucial for the in vivo d -lactate utilization function of Fe-S d -iLDH. IMPORTANCE Lactate metabolism plays versatile roles in most domains of life. Lactate utilization processes depend on certain enzymes to oxidize lactate to pyruvate. In recent years, novel bacterial lactate-oxidizing enzymes have been continually reported, including the unique NAD-independent d -lactate dehydrogenase that contains an Fe-S oxidoreductase domain besides the typical flavin-containing domain (Fe-S d -iLDH). Although Fe-S d -iLDH is widely distributed among bacterial species, the investigation of it is insufficient. Fe-S d -iLDH from Pseudomonas putida KT2440, which is the major d -lactate-oxidizing enzyme for the strain, might be a representative of this type of enzyme. A study of it will be helpful in understanding the detailed mechanisms underlying the lactate utilization processes.