Rational Design of Highly Phosphorescent Nanoclusters for Efficient Photocatalytic Oxidation.

Analyzing the molecular structure-photophysical property correlations of metal nanoclusters to accomplish function-oriented photocatalysis could be challenging. Here, the selective heteroatom alloying has been exploited to a Au15 nanocluster, making up a structure-correlated nanocluster series, including homogold Au15, bimetallic AgxAu15-x and CuxAu15-x, trimetallic AgxCuyAu15-x-y, and tetrametallic Pt1AgxCuyAu15-x-y. Their structure-dependent photophysical properties were investigated due to the atomically precise structures of these nanoclusters. Cu-alloyed CuxAu15-x showed intense phosphorescence and the highest singlet oxygen production efficiency. Moreover, the generation of 1O2 species from excited nanoclusters enabled CuxAu15-x as a suitable catalyst for efficient photocatalytic oxidation of silyl enol ethers to produce α,ß-unsaturated carbonyl compounds. The generality and applicability of the CuxAu15-x catalysts toward different photocatalytic oxidations were assessed. Overall, this study presents an intriguing Au15-based cluster series enabling an atomic-level understanding of structure-photophysical property correlations, which hopefully provides guidance for the fabrication of cluster-based catalysts with customized photocatalytic performance.

A nitroreductase DnrA catalyzes the biotransformation of several diphenyl ether herbicides in Bacillus sp. Za.

Diphenyl ether herbicides, typical globally used herbicides, threaten the agricultural environment and the sensitive crops. The microbial degradation pathways of diphenyl ether herbicides are well studied, but the nitroreduction of diphenyl ether herbicides by purified enzymes is still unclear. Here, the gene dnrA, encoding a nitroreductase DnrA responsible for the reduction of nitro to amino groups, was identified from the strain Bacillus sp. Za. DnrA had a broad substrate spectrum, and the Km values of DnrA for different diphenyl ether herbicides were 20.67 µM (fomesafen), 23.64 µM (bifenox), 26.19 µM (fluoroglycofen), 28.24 µM (acifluorfen), and 36.32 µM (lactofen). DnrA also mitigated the growth inhibition effect on cucumber and sorghum through nitroreduction. Molecular docking revealed the mechanisms of the compounds fomesafen, bifenox, fluoroglycofen, lactofen, and acifluorfen with DnrA. Fomesafen showed higher affinities and lower binding energy values for DnrA, and residue Arg244 affected the affinity between diphenyl ether herbicides and DnrA. This research provides new genetic resources and insights into the microbial remediation of diphenyl ether herbicide-contaminated environments. KEY POINTS: • Nitroreductase DnrA transforms the nitro group of diphenyl ether herbicides. • Nitroreductase DnrA reduces the toxicity of diphenyl ether herbicides. • The distance between Arg244 and the herbicides is related to catalytic efficiency.

Wireless, battery-free subdermally implantable photometry systems for chronic recording of neural dynamics.

Recording cell-specific neuronal activity while monitoring behaviors of freely moving subjects can provide some of the most significant insights into brain function. Current means for monitoring calcium dynamics in genetically targeted populations of neurons rely on delivery of light and recording of fluorescent signals through optical fibers that can reduce subject mobility, induce motion artifacts, and limit experimental paradigms to isolated subjects in open, two-dimensional (2D) spaces. Wireless alternatives eliminate constraints associated with optical fibers, but their use of head stages with batteries adds bulk and weight that can affect behaviors, with limited operational lifetimes. The systems introduced here avoid drawbacks of both types of technologies, by combining highly miniaturized electronics and energy harvesters with injectable photometric modules in a class of fully wireless, battery-free photometer that is fully implantable subdermally to allow for the interrogation of neural dynamics in freely behaving subjects, without limitations set by fiber optic tethers or operational lifetimes constrained by traditional power supplies. The unique capabilities of these systems, their compatibility with magnetic resonant imaging and computed tomography and the ability to manufacture them with techniques in widespread use for consumer electronics, suggest a potential for broad adoption in neuroscience research.

Wireless optoelectronic photometers for monitoring neuronal dynamics in the deep brain.

Capabilities for recording neural activity in behaving mammals have greatly expanded our understanding of brain function. Some of the most sophisticated approaches use light delivered by an implanted fiber-optic cable to optically excite genetically encoded calcium indicators and to record the resulting changes in fluorescence. Physical constraints induced by the cables and the bulk, size, and weight of the associated fixtures complicate studies on natural behaviors, including social interactions and movements in environments that include obstacles, housings, and other complex features. Here, we introduce a wireless, injectable fluorescence photometer that integrates a miniaturized light source and a photodetector on a flexible, needle-shaped polymer support, suitable for injection into the deep brain at sites of interest. The ultrathin geometry and compliant mechanics of these probes allow minimally invasive implantation and stable chronic operation. In vivo studies in freely moving animals demonstrate that this technology allows high-fidelity recording of calcium fluorescence in the deep brain, with measurement characteristics that match or exceed those associated with fiber photometry systems. The resulting capabilities in optical recordings of neuronal dynamics in untethered, freely moving animals have potential for widespread applications in neuroscience research.

[Intelligent Nursing System].

An intelligent nursing system for hospital wards is designed. With STM32 as the core and Internet of things technology, the intelligent nursing system can obtain body temperature, heart rate and control all the facilities in the ward by itself through the mobile APP. The intelligent nursing system has the advantages of simple operation, high accuracy of measurement data, stiff stability and good real-time performance. It can not only realize comprehensive real-time health monitoring for patients, but also greatly reduce the workload of nurses and improve work efficiency.

A plasmid-based genomic screening system for transcriptional regulators of non-adjacent xenobiotic catabolism genes.

Bacteria play an important role in the catabolism of environmental xenobiotics. The study of transcriptional regulation has greatly enhanced our understanding of the molecular mechanisms associated with these processes. However, genes encoding transcription factors (TFs) for xenobiotic catabolism are usually not located in the immediate vicinity of the catabolic genes that they regulate; therefore, functional identification of these TFs is difficult. Significantly modified from a metagenome screening method substrate-induced gene expression (SIGEX), here we propose a synthetic pSRGFP-18 plasmid-based tool as a TF reporter system. In short, two multiple cloning sites (MCS) were designed; one in front of an egfp reporter gene was constructed for promoter insertion, and the other MCS was used for shotgun cloning of genomic DNA. Based on the regulatory relationship between TFs and the promoter of their associated catabolic genes, this approach allowed us to screen for TF genes using a genome shotgun approach. This system performed well when testing the known operons. Following statistical analysis of known catabolic operons in Escherichia coli and Bacillus subtilis, the suggested region of the target promoter for this system was from - 250 to + 150. Furthermore, to broaden the applicability of this plasmid, a series of pSRGFP-18 and pBBR1-based pSRGFP-X plasmids were constructed, which had broad host ranges and contained different antibiotic markers. This study outlines a powerful tool to enable functional identification of TFs for bacterial xenobiotic catabolism.

Morphable 3D mesostructures and microelectronic devices by multistable buckling mechanics.

Three-dimensional (3D) structures capable of reversible transformations in their geometrical layouts have important applications across a broad range of areas. Most morphable 3D systems rely on concepts inspired by origami/kirigami or techniques of 3D printing with responsive materials. The development of schemes that can simultaneously apply across a wide range of size scales and with classes of advanced materials found in state-of-the-art microsystem technologies remains challenging. Here, we introduce a set of concepts for morphable 3D mesostructures in diverse materials and fully formed planar devices spanning length scales from micrometres to millimetres. The approaches rely on elastomer platforms deformed in different time sequences to elastically alter the 3D geometries of supported mesostructures via nonlinear mechanical buckling. Over 20 examples have been experimentally and theoretically investigated, including mesostructures that can be reshaped between different geometries as well as those that can morph into three or more distinct states. An adaptive radiofrequency circuit and a concealable electromagnetic device provide examples of functionally reconfigurable microelectronic devices.

Transmission matrix-based Electric field Monte Carlo study and experimental validation of the propagation characteristics of Bessel beams in turbid media.

A novel Transmission matrix-based Electric field Monte Carlo (TEMC) method is introduced to study the propagation characteristics of Bessel beams with different orbital angular momentum (OAM) in turbid media. As an extension to the Electric field Monte Carlo (EMC) approach, electric field transmission modes were simulated to properly evaluate light interference. Beam transmission patterns, intensity attenuation, and the degree of polarization (DOP) through turbid media of varying thickness were analyzed. It was found that the OAM plays a subtle role in transmission through turbid media, showing only a weak correlation with total transmission, the preservation of DOP, and the penetration depth. The TEMC simulation results were in excellent agreement with experiments, validating the proposed method for the study of coherence phenomenon in turbid media.

Paenibacillus yanchengensis sp. nov., isolated from farmland soil.

A Gram-variable, short-rod-shaped, motile, spore-forming, strictly aerobic and alkaliresistant bacterium, designed strain J-3T, was isolated from farmland soil sampled in Yancheng city, Jiangsu province, China. Optimal growth occurred at 30 °C, pH 7.0-8.0 and 0.5 % (w/v) NaCl. Phylogenetic analysis based on the 16S rRNA gene sequences showed that strain J-3T was most closely related to Paenibacillusripae HZ1T (96.8 %), followed by Paenibacillussputi KIT00200-70066-1T (94.7 %). The major cellular fatty acids were anteiso-C15 : 0 and C16 : 0. The dominant respiratory quinone was menaquinone-7 and the DNA G+C content was 41.2 mol%. The major polar lipids of strain J-3T were aminolipid, phospholipid, diphosphatidylglycerol, phosphatidylglycerol, phosphoaminolipid and phosphatidylethanolamine. The diagnostic diamino acid of the cell-wall peptidoglycan was meso-diaminopimelic acid. On the basis of genotypic and phenotypic data, strain J-3T represents a novel species of the genus Paenibacillus, for which the name Paenibacillus yanchengensis sp. nov. is proposed. The type strain is J-3T (=KCTC 33926T=CGMCC 1.16455T).

Cooperative plasmonic effect of Ag and Au nanoparticles on enhancing performance of polymer solar cells.

This article describes a cooperative plasmonic effect on improving the performance of polymer bulk heterojunction solar cells. When mixed Ag and Au nanoparticles are incorporated into the anode buffer layer, dual nanoparticles show superior behavior on enhancing light absorption in comparison with single nanoparticles, which led to the realization of a polymer solar cell with a power conversion efficiency of 8.67%, accounting for a 20% enhancement. The cooperative plasmonic effect aroused from dual resonance enhancement of two different nanoparticles. The idea was further unraveled by comparing Au nanorods with Au nanoparticles for solar cell application. Detailed studies shed light into the influence of plasmonic nanostructures on exciton generation, dissociation, and charge recombination and transport inside thin film devices.

The role of N-doped multiwall carbon nanotubes in achieving highly efficient polymer bulk heterojunction solar cells.

This paper reports an improved solar cell performance of 8.6% by incorporation of N-doped multiwall carbon nanotubes (N-MCNTs) into BHJ solar cells composed of PTB7 and PC71BM. It was demonstrated for the first time that incorporation of N-MCNTs leads to not only increased nanocrystallite sizes but also smaller phase-separated domain sizes of both PTB7 copolymers and PC71BM from X-ray scattering study. The results show that N-MCNTs could serve as both exciton dissociation centers and charge transfer channels. The enhanced charge dissociation probabilities and effective charge carrier lifetime in the active layer material offer evidence to support the conclusion that N-MCNTs facilitated charge separation and transport.

Size disproportionation among nanocluster transformations.

Controllable transformation is a prerequisite to the in-depth understanding of structure evolution mechanisms and structure-property correlations at the atomic level. Most transformation cases direct the directional evolution of nanocluster sizes, i.e., size-maintained, size-increased, or size-reduced transformation, while size disproportionation was rarely reported. Here, we report the Au-doping-induced size disproportionation of nanocluster transformation. Slight Au-doping on the bimetallic (AgCu)43 nanocluster produced its trimetallic derivative, (AuAgCu)43, following a size-maintained transformation. By comparison, the (AgCu)43 nanocluster underwent a size-disproportionation transformation under heavy Au alloying, leading to the formation of size-reduced (AuAgCu)33 and size-increased (AuAgCu)56 nanoclusters simultaneously. Such a size disproportionation among the nanocluster transformations was verified by the thin-layer chromatography analysis. This work presented a novel nanocluster transformation case with a size disproportionation characteristic, expected to provide guidance for the understanding of cluster size evolutions.

Recent Progress on Transparent Microelectrode-Based Soft Bioelectronic Devices for Neuroscience and Cardiac Research.

Transparent microelectrodes have emerged as promising tools to combine electrical and optical sensing and modulation modalities in many areas of biological and biomedical research. Compared to conventional opaque microelectrodes, they offer a number of specific advantages that can enable advances in functionality and performance. In addition to optical transparency, the mechanical softness feature is desired to minimize foreign body responses, increase biocompatibility, and avoid loss of functionality. In this review, we present recent research from the past several years on transparent microelectrode-based soft bioelectronic devices with an emphasis on their material properties and advanced device designs, as well as multimodal application scenarios for neuroscience and cardiology. First, we introduce material candidates with proper electrical, optical, and mechanical properties for soft transparent microelectrodes. We then discuss examples of soft transparent microelectrode arrays tailored to combine electrical recording and/or stimulation with optical imaging and/or optogenetic modulation of the brain and the heart. Next, we summarize the most recent progress on soft opto-electric devices integrating transparent microelectrodes with microscale light-emitting diodes and/or photodetectors into single and hybrid microsystems as powerful tools to explore the brain and heart functions. A brief overview of possible future directions of soft transparent microelectrode-based biointerfaces is provided to conclude the review.

Soft, bioresorbable, transparent microelectrode arrays for multimodal spatiotemporal mapping and modulation of cardiac physiology.

Transparent microelectrode arrays (MEAs) that allow multimodal investigation of the spatiotemporal cardiac characteristics are important in studying and treating heart disease. Existing implantable devices, however, are designed to support chronic operational lifetimes and require surgical extraction when they malfunction or are no longer needed. Meanwhile, bioresorbable systems that can self-eliminate after performing temporary functions are increasingly attractive because they avoid the costs/risks of surgical extraction. We report the design, fabrication, characterization, and validation of a soft, fully bioresorbable, and transparent MEA platform for bidirectional cardiac interfacing over a clinically relevant period. The MEA provides multiparametric electrical/optical mapping of cardiac dynamics and on-demand site-specific pacing to investigate and treat cardiac dysfunctions in rat and human heart models. The bioresorption dynamics and biocompatibility are investigated. The device designs serve as the basis for bioresorbable cardiac technologies for potential postsurgical monitoring and treating temporary patient pathological conditions in certain clinical scenarios, such as myocardial infarction, ischemia, and transcatheter aortic valve replacement.

Transparent and Stretchable Au─Ag Nanowire Recording Microelectrode Arrays.

Transparent microelectrodes have received much attention from the biomedical community due to their unique advantages in concurrent crosstalk-free electrical and optical interrogation of cell/tissue activity. Despite recent progress in constructing transparent microelectrodes, a major challenge is to simultaneously achieve desirable mechanical stretchability, optical transparency, electrochemical performance, and chemical stability for high-fidelity, conformal, and stable interfacing with soft tissue/organ systems. To address this challenge, we have designed microelectrode arrays (MEAs) with gold-coated silver nanowires (Au─Ag NWs) by combining technical advances in materials, fabrication, and mechanics. The Au coating improves both the chemical stability and electrochemical impedance of the Au─Ag NW microelectrodes with only slight changes in optical properties. The MEAs exhibit a high optical transparency >80% at 550 nm, a low normalized 1 kHz electrochemical impedance of 1.2-7.5 Ω cm2, stable chemical and electromechanical performance after exposure to oxygen plasma for 5 min, and cyclic stretching for 600 cycles at 20% strain, superior to other transparent microelectrode alternatives. The MEAs easily conform to curvilinear heart surfaces for colocalized electrophysiological and optical mapping of cardiac function. This work demonstrates that stretchable transparent metal nanowire MEAs are promising candidates for diverse biomedical science and engineering applications, particularly under mechanically dynamic conditions.

Examining the effect of the dipole moment on charge separation in donor-acceptor polymers for organic photovoltaic applications.

A new low band gap copolymer PBB3 containing [6,6']bi[thieno[3,4-b]thiophenyl]-2,2'-dicarboxylic acid bis-(2-butyloctyl) ester (BTT) and 4,8-bis(2-butyloctyl)benzo[1,2-b:4,5-b']dithiophene (BDT) units was synthesized and tested for solar cell efficiency. PBB3 showed a broad absorbance in the near-IR region with a substantially red-shifted (by more than 100 nm) λ(max) at 790 nm as compared to the PTB series of polymers, which have been previously reported. The PBB3 polymer also showed both a favorable energy level match with PCBM (with a LUMO energy level of -3.29 eV) and a favorable film domain morphology as evidenced by TEM images. Despite these seemingly optimal parameters, a bulk heterojunction (BHJ) photovoltaic device fabricated from a blend of PBB3 and PC(71)BM showed an overall power conversion efficiency (PCE) of only 2.04% under AM 1.5G/100 mW cm(-2). The transient absorption spectra of PBB3 showed the absence of cationic and pseudo charge transfer states that were observed previously in the PTB series polymers, which were also composed of alternating thienothiophene (TT) and BDT units. We compared the spectral features and electronic density distribution of PBB3 with those of PTB2, PTB7, and PTBF2. While PTB2 and PTB7 have substantial charge transfer characteristics and also relatively large local internal dipoles through BDT to TT moieties, PTBF2 and PBB3 have minimized internal dipole moments due to the presence of two adjacent TT units (or two opposing fluorine atoms in PTBF2) with opposite orientations or internal dipoles. PBB3 showed a long-lived excitonic state and the slowest electron transfer dynamics of the series of polymers, as well as the fastest recombination rate of the charge-separated (CS) species, indicating that electrons and holes are more tightly bound in these species. Consequently, substantially lower degrees of charge separation were observed in both PBB3 and PTBF2. These results show that not only the energetics but also the internal dipole moment along the polymer chain may be critical in maintaining the pseudocharge transfer characteristics of these systems, which were shown to be partially responsible for the high PCE device made from the PTB series of low band gap copolymers.

Simulation of the effect of rogue ryanodine receptors on a calcium wave in ventricular myocytes with heart failure.

Calcium homeostasis is considered to be one of the most important factors for the contraction and relaxation of the heart muscle. However, under some pathological conditions, such as heart failure (HF), calcium homeostasis is disordered, and spontaneous waves may occur. In this study, we developed a mathematical model of formation and propagation of a calcium wave based upon a governing system of diffusion-reaction equations presented by Izu et al (2001 Biophys. J. 80 103-20) and integrated non-clustered or 'rogue' ryanodine receptors (rogue RyRs) into a two-dimensional (2D) model of ventricular myocytes isolated from failing hearts in which sarcoplasmic reticulum (SR) Ca(2+) pools are partially unloaded. The model was then used to simulate the effect of rogue RyRs on initiation and propagation of the calcium wave in ventricular myocytes with HF. Our simulation results show that rogue RyRs can amplify the diastolic SR Ca(2+) leak in the form of Ca(2+) quarks, increase the probability of occurrence of spontaneous Ca(2+) waves even with smaller SR Ca(2+) stores, accelerate Ca(2+) wave propagation, and hence lead to delayed afterdepolarizations (DADs) and cardiac arrhythmia in the diseased heart. This investigation suggests that incorporating rogue RyRs in the Ca(2+) wave model under HF conditions provides a new view of Ca(2+) dynamics that could not be mimicked by adjusting traditional parameters involved in Ca(2+) release units and other ion channels, and contributes to understanding the underlying mechanism of HF.

Flexible and Transparent Metal Oxide/Metal Grid Hybrid Interfaces for Electrophysiology and Optogenetics.

Flexible and transparent microelectrodes and interconnects provide the unique capability for a wide range of emerging biological applications, including simultaneous optical and electrical interrogation of biological systems. For practical biointerfacing, it is important to further improve the optical, electrical, electrochemical, and mechanical properties of the transparent conductive materials. Here, high-performance microelectrodes and interconnects with high optical transmittance (59-81%), superior electrochemical impedance (5.4-18.4 Ω cm2), and excellent sheet resistance (5.6-14.1 Ω sq-1), using indium tin oxide (ITO) and metal grid (MG) hybrid structures are demonstrated. Notably, the hybrid structures retain the superior mechanical properties of flexible MG other than brittle ITO with no changes in sheet resistance even after 5000 bending cycles against a small radius at 5 mm. The capabilities of the ITO/MG microelectrodes and interconnects are highlighted by high-fidelity electrical recordings of transgenic mouse hearts during co-localized programmed optogenetic stimulation. In vivo histological analysis reveals that the ITO/MG structures are fully biocompatible. Those results demonstrate the great potential of ITO/MG interfaces for broad fundamental and translational physiological studies.

Spatial remodelling of calcium release units may impair cardiac electro-mechanical function: A simulation study.

Excitation-contraction coupling (E-C coupling) is thought to be based on elementary calcium release units (CRUs) in which clusters of ryanodine receptors (RyRs) localized on the sarcoplasmic reticulum (SR) are in close apposition to L-type Ca2+ channels (LCCs) on the transverse tubules (TTs). However, a fraction of LCC-RyR structure may be uncoupled due to the remodelling of TTs, which would tend to destroy the E-C coupling in the failing heart. Here we proposed a multiscale model of the ventricular myocyte to investigate the relationship between LCC-RyR structure and cardiac electro-mechanical function. The mathematical model consisted of a two-dimensional (2D) subcellular Ca2+ reaction-diffusion sub-model, a cellular electrophysiological sub-model and a cardiomyocyte contraction sub-model. The simulation results showed that the remodelling of CRU microstructure would disturb Ca2+ homeostasis, leading to a dyssynchronous Ca2+ transient, and postpone the generation of isometric force. Our study suggests that structural remodelling is an important mechanism for dysfunction of Ca2+ handling, cellular electrophysiology and contractility in failing heart.