Model Organic Surfaces to Probe Marine Bacterial Adhesion Kinetics by Surface Plasmon Resonance

Understanding how bacteria adhere to a surface is a critical step in the development of novel materials and coatings to prevent bacteria forming biofilms. Here, surface plasmon resonance (SPR) spectroscopy, in combination with self‐assembled monolayers (SAMs) that have different backbone structures and/or functional groups, is used for the first time to study the initial stages of bacterial adhesion to surfaces (i.e., initial interaction of cells with a surface, a process governed by van der Waals, electrostatic, and hydrophobic interactions). The work highlights SPR spectroscopy as a powerful and unique approach to probe bacterial adhesion in real time. SPR spectral data reveal different kinetics of adhesion for the interaction of two marine bacterial species (Marinobacter hydrocarbonoclasticus and Cobetia marina) to a range of organosulfur SAMs. Furthermore, the extent of adhesion is dependent on the backbone structures and functional groups of the SAMs. The role of extracellular polymeric substances (EPS) in bacterial adhesion is also investigated. Pre‐conditioning experiments with cell‐free culture supernatants, containing planktonic EPS, allow quantification of the amount adsorbed onto surfaces and directly account for the impact of EPS adsorption on bacterial adhesion in the assay. While the physicochemical characteristics of the surfaces play a significant role in determining bacterial cell adhesion for low levels of conditioning by planktonic EPS, greater levels of conditioning by EPS reduce the difference between surfaces.     

A Tailored Artificial DNase Blocks Sensor Activation and Prevents Autoimmune and Autoinflammatory Diseases

Excessive self-DNAs recognized by intracellular DNA sensors can initiate innate immunity to express disordered TNF-α or type I IFN resulting in several autoimmune diseases. Cationic polymers have been profoundly proved to alleviate the inflammatory symptoms by removing the debris of cell-free DNA (cfDNA). However, clinical applications of cationic materials have been impeded by concerns of their toxicity and the fate of cfDNA in polymer-cfDNA complex. Herein, it is showed that PEGylated polyimidazoles as a biomimetic DNase potently alleviate pathologic symptoms of self-DNA-associated rheumatoid arthritis (RA) rats and Trex1 (DNase III) deficient Aicardi-Goutiéres syndrome (AGS) mice. The mechanism studies demonstrate that the polyimidazole efficiently attacks the phosphodiester linkages of NAs and cleavages them into small pieces. As imidazole unit is a much weaker organic base that occurs in natural proteins, the polyimidazoles are less toxic to cells and tissues, as manifested by the IC50 values larger than 1000 µg mL⁻¹. This work suggests that synthetic tailored DNase can be a new and safe therapeutic agent to treat chronic autoimmune and refractory inflammatory diseases by degradation of excessive nucleic acids.     

Hydrogel Adhesion: A Supramolecular Synergy of Chemistry,Topology, and Mechanics

Adhering hydrogels to various materials is fundamental to a large array of established and emerging applications. The last few years have seen transformative advances in achieving strong hydrogel adhesion, which is a supramolecular phenomenon. Two adherends connect through covalent bonds, noncovalent complexes, polymer chains, polymer networks, or nanoparticles. Separating the adherends dissipates energy through cascading events across length scales, including bond cleavage, chain retraction, and bulk hysteresis. A unifying principle has emerged: strong hydrogel adhesion requires the synergy of chemistry of bonds, topology of connection, and mechanics of dissipation. This synergy characterizes hydrogel adhesion to various materials (another hydrogel, tissue, elastomer, plastic, metal, glass, and ceramic) in various operations (cast, coat, print, attach, pierce, and glue). Strong adhesion can be made permanent, reversible, degradable, or on‐demand detachable. The development of hydrogel adhesion and its applications adheres disciplines, discovers interlinks, and forges cohesion. Discussed throughout the review are immediate opportunities for fundamental studies and practical applications.     

A Microneedle Technology for Sampling and Sensing Bacteria in the Food Supply Chain

Food quality monitoring, particularly, the detection of bacterial pathogens and spoilage throughout the food supply chain, is critical to ensure global food safety and minimize food loss. Incorporating sensors into packaging is promising, but it is challenging to achieve the required sampling volume while using food-safe sensor materials. Here, by leveraging water-based processing of silk fibroin, a platform for the detection of pathogenic bacteria in food is realized using a porous silk microneedle array; the microneedle array samples fluid from the interior of the food by capillary action, presenting the fluid to polydiacetylene-based bioinks printed on the backside of the array. Through the colorimetric response of bioink patterns, Escherichia coli contamination in fish fillets is identified within 16 h of needle injection. This response is distinct from spoilage measured via the increase in sample pH. It is also shown that the microneedles can pierce commercial food packaging, and subsequently sample fluid and present it to the sensor, enabling the adaptation of the technology downstream in food supply chains such as in stores or at home. This study highlights that regenerated structural biopolymers can serve as safe materials for food contact and sensing with robust mechanical properties and tailored chemistry.     

铬过渡层对银膜光学性质及附着力的影响

研究了在玻璃基底上采用不同厚度的铬膜作过渡层,对银膜的光学性质及其附着力的影响。光谱测量结果表明,随着铬膜层厚度的增加,银膜的反射率先增大后减小。与直接镀在玻璃基底上的银膜的反射率相比,铬膜层厚度为8~14nm时,银膜的反射率较低;铬膜层厚度为17~21nm时,银膜的反射率得到提高,其中铬膜厚度为17nm时,银膜的反射率最高;继续增加铬膜层的厚度,银膜的反射率又降低,说明采用一定厚度的铬膜作过渡层可以提高银膜的反射率。X射线衍射(XRD)结构分析表明,一定厚度的铬膜改善了银膜的结晶程度,使薄膜的晶粒度增大,晶界散射及缺陷减少,从而使应变减小。剥落实验证明薄膜与玻璃基底之间的附着力也得到了提高。     

Biological Assemblies Provide Novel Templates for the Synthesis of Biocomposites and Facilitate Cell Adhesion

Mechanical mismatch and the lack of interactions between implants and the natural tissue environment are major drawbacks in bone tissue engineering. Biomaterials mimicking the self‐assembly process and the composition of the bone matrix should provide new routes for fabricating biomaterials possessing novel osteoconductive and osteoinductive properties for bone repair. In the present study, bioinspired strategies are employed to design de novo self‐assembled chimeric protein hydrogels comprising leucine zipper motifs flanking a dentin matrix protein 1 domain, which is characterized as a mineralization nucleator. Results show that this chimeric protein could function as a hydroxyapatite nucleator in pseudo‐physiological buffer with the formation of highly oriented apatites similar to biogenic bone mineral. It could also function as an inductive substrate for osteoblast adhesion, promote cell surface integrin presentation and clustering, and modulate the formation of focal contacts. Such biomimetic “bottom‐up” construction with dual osteoconductive and osteoinductive properties should open new avenues for bone tissue engineering.     

Rapid and Facile Formation of P3HT Organogels via Spin Coating: Tuning Functional Properties of Organic Electronic Thin Films

Poly(3‐hexyl thiophene) (P3HT) is widely regarded as the benchmark polymer when studying the physics of conjugated polymers used in organic electronic devices. P3HT can self‐assemble via π–π stacking of its backbone, leading to an assembly and growth of P3HT fibrils into 3D percolating organogels. These structures are capable of bridging the electrodes, providing multiple pathways for charge transport throughout the active layer. Here, a novel set of conditions is identified and discussed for P3HT organogel network formation via spin coating by monitoring the spin‐coating process from various solvents. The development of organogel formation is detected by in situ static light scattering, which measures both the thinning rate by reflectance and structural development in the film via off‐specular scattering during film formation. Optical microscopy and thermal annealing experiments provide ex situ confirmation of organogel fabrication. The role of solution characteristics, including solvent boiling point, P3HT solubility, and initial P3HT solution concentration on organogel formation, is examined to correlate these parameters to the rate of film formation, organogel‐onset concentration, and overall network size. The correlation of film properties to the fabrication parameters is also analyzed within the context of the hole mobility and density‐of‐states measured by impedance spectroscopy.     

涂层界面失效破坏临界位置的理论分析与实验研究

根据红外激光划痕时在涂层表面产生的温度场的理论分析,找出涂层界面失效破坏的临界位置.在实验研究中,分析红外热成像仪对激光划痕涂层的实时温度检测结果,表明在涂层逐渐失效破坏的过程中,其表面的温度状况呈现出与理论分析结果相一致的两阶段的变化,进而说明了温度变化的转折点即是该涂层从基体脱落下来的临界位置;并通过计算得知,该涂层临界脱落点对应的激光辐射功率大约为31.92 W,这一结果直接反映了该涂层与基体结合强度的情况.     

Remote Manipulation of Slidable Nano‐Ligand Switch Regulates the Adhesion and Regenerative Polarization of Macrophages

The development of materials capable of varying macroscale ligand distributions can emulate an extracellular matrix (ECM) remodeling and regulate the adhesion and polarization of macrophages. In this report, negatively charged slidable nano‐ligands are assembled and then conjugated to a positively charged substrate via electrostatic interaction. The negatively charged slidable nano‐ligands are prepared by coating magnetic nanoparticles with a polymer linker and negatively charged RGD ligand. The nano‐ligand sliding is characterized under an external magnetic field, which spatiotemporally alters macroscale ligand density. To the best of knowledge, this is the first demonstration that magnetic maipulation of the macroscale ligand density inhibits inflammatory M1 phenotype but stimulates the adhesion and regenerative M2 phenotype of host macrophages. Furthermore, it is elucidated that the magnetic attraction of the slidable nano‐ligand facilitates the assembly of adhesion structures in macrophages, thereby stimulating their regenerative M2 phenotype. The design of ECM‐emulating materials that allow remote, spatiotemporal, and reversible controllability of macroscale ligand density provides an appealing strategy in the spatiotemporal regulation of immunomodulatory tissue‐regenerative responses to implants in vivo.     

Morphology‐Control Strategy of the Superhydrophobic Poly(Methyl Methacrylate) Surface for Efficient Bubble Adhesion and Wastewater Remediation

As one common form of gas existing in aqueous environment, gas bubbles have attracted considerable worldwide attention, owing to their promising applications in industrial production and daily life, such as pressure sensors, the recovery of valuable minerals from ores, aeration process, and water treatment. Usually, the behaviors of gas bubbles in aqueous environment are mainly dominated by buoyancy force. It drives the gas bubbles out of aqueous medium rapidly, which is unfavorable in various processes, especially in wastewater treatment. In this paper, various types of superhydrophobic poly(methyl methacrylate) (PMMA) sheets are facilely fabricated, such as five‐pointed star, triangle, circular, and ellipse. Compared with other shapes of superhydrophobic PMMA sheets, the prepared superhydrophobic PMMA circular sheet is capable of efficiently adhering gas bubbles and subsequently elongating their retention time in an aqueous environment. Furthermore, superhydrophobic PMMA circular sheet arrays are prepared, which can greatly improve the degradation efficiency of methyl blue by ozone (O₃). The investigations indicate that the present approach will find wild applications in bubble‐related fields and provide people with inspirations to develop efficient methods to manipulate gas bubbles in aqueous environment.     

Melt Electrowriting Allows Tailored Microstructural and Mechanical Design of Scaffolds to Advance Functional Human Myocardial Tissue Formation

Engineering native‐like myocardial muscle, recapitulating its fibrillar organization and mechanical behavior is still a challenge. This study reports the rational design and fabrication of ultrastretchable microfiber scaffolds with controlled hexagonal microstructures via melt electrowriting (MEW). The resulting structures exhibit large biaxial deformations, up to 40% strain, and an unprecedented compliance, delivering up to 40 times more elastic energy than rudimentary MEW fiber scaffolds. Importantly, when human induced pluripotent stem cell‐derived cardiomyocytes (iPSC‐CM) are encapsulated in a collagen‐based hydrogel and seeded on these microstructured and mechanically tailored fiber scaffolds, they show an increase in beating rate (1.5‐fold), enhanced cell alignment, sarcomere content and organization as well as an increase in cardiac maturation‐related marker expression (Cx43 1.8‐fold, cardiac Actin 1.5‐fold, SERCA2a 2.5‐fold, KCNJ2 1.5‐fold, and PPARGC1a 3.6‐fold), indicative of enhanced iPSC‐CM maturation, as compared to rudimentary fiber scaffolds. By combining these novel fiber scaffolds with clinically relevant human iPSC‐CMs, a heart patch that allows further maturation of contractile myocytes for cardiac tissue engineering is generated. Moreover, the designed scaffold allows successful shape recovery after epicardial delivery on a beating porcine heart, without negative effects on the engineered construct and iPSC‐CM viability.     

A Synthetic Hydrogel Composite with the Mechanical Behavior and Durability of Cartilage

This article reports the first hydrogel with the strength and modulus of cartilage in both tension and compression, and the first to exhibit cartilage‐equivalent tensile fatigue strength at 100 000 cycles. These properties are achieved by infiltrating a bacterial cellulose (BC) nanofiber network with a poly(vinyl alcohol) (PVA)–poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid sodium salt) (PAMPS) double network hydrogel. The BC provides tensile strength in a manner analogous to collagen in cartilage, while the PAMPS provides a fixed negative charge and osmotic restoring force similar to the role of aggrecan in cartilage. The hydrogel has the same aggregate modulus and permeability as cartilage, resulting in the same time‐dependent deformation under confined compression. The hydrogel is not cytotoxic, has a coefficient of friction 45% lower than cartilage, and is 4.4 times more wear‐resistant than a PVA hydrogel. The properties of this hydrogel make it an excellent candidate material for replacement of damaged cartilage.     

Luminescence of Functionalized Carbon Nanotubes as a Tool to Monitor Bundle Formation and Dissociation in Water: The Effect of Plasmid‐DNA Complexation

Functionalized carbon nanotubes (f‐CNTs) are explored as novel nanomaterials for biomedical applications. UV‐vis luminescence of aqueous dispersions of CNT–NH₃⁺ and CNT–NH–Ac (NH–Ac: acetamido) is observed using standard laboratory spectrophotometric instrumentation, and the measured fluorescence intensity is correlated with the aggregation state of the f‐CNTs: a high intensity indicates improved f‐CNT individualization and dispersion, while a decrease in fluorescence intensity indicates a higher degree of nanotube aggregation and bundling as a result of varying the sodium dodecyl sulfate (SDS) concentrations and pH in the aqueous phase. Moreover, utilization of this relationship between fluorescence intensity and the state of f‐CNT aggregation is carried out to elucidate the interactions between f‐CNTs and gene‐encoding plasmid DNA (pDNA). pDNA is shown to interact with CNT–NH₃⁺ primarily through electrostatic interactions that lead concomitantly to a higher degree of f‐CNT bundling. The CNT–NH₃⁺/pDNA interactions are successfully competed by SDS/f‐CNT surface interactions, resulting in the displacement of pDNA. These studies provide exemplification of the use of fluorescence spectrophotometry to accurately describe the aggregation state of water‐soluble f‐CNTs. Characterization of the complexes between pDNA and f‐CNTs elucidates the opportunities and limitations of such supramolecular systems as potential vectors for gene transfer.     

基于MODIS图像I类水和II类水的

通过统计分析多景MODIS图像,提出了一种基于MODIS图像识别I类水体和II类水体的经验方法。该经验方法是利用I类 水和II类水在可见光区的反射率差别大、而在近红外波段两者的反射率基本相同的特性来完成的。把该经验方法用在了中 国渤海区域,对不同年份的两景MODIS图像进行了I类水与II类水识别,并对结果进行了分析,结果证明该经验方法是正确和有效的。     

A Combined Photolithographic and Molecular‐Assembly Approach to Produce Functional Micropatterns for Applications in the Biosciences

Chemical patterns have attracted substantial interest for applications in the field of biosensors, fundamental cell–surface interaction studies, tissue engineering, and biomaterials. A novel micropatterning technique is proposed here that combines a top–down approach based on photolithography and a bottom–up strategy through self‐organization of multifunctional molecules. The development of the molecular‐assembly patterning by lift‐off (MAPL) has been driven by the need to economically produce patches incorporating a controlled surface density of bioligands while inhibiting non‐specific adsorption. In the MAPL process, a photoresist pattern is transferred into the desired biochemical pattern by means of spontaneous adsorption of biologically relevant species and photoresist lift‐off. The surface between the interactive patches is subsequently rendered non‐fouling through immobilization of a polycationic poly(ethylene glycol) (PEG)‐graft polymer. We demonstrate that surface density of biotin molecules inside adhesive islands can be tailored quantitatively and that cells grow selectively on cell‐adhesive peptide patterns. MAPL is considered to be a valuable addition to the toolbox of soft‐lithography techniques for life‐science applications combining simplicity (no clean‐room equipment needed), cost‐effectiveness, reproducibility on the scale of whole wafer surfaces, and flexibility in terms of pattern geometry, chemistry, and substrate choice.     

雷达信号基因形成机理与多层次建模方法研究

针对电子对抗侦察领域对截获雷达信号认知的需求,对雷达信号基因的形成机理和建模问题进行研究。首先,分析了雷达信号的不同层次和层次之间的转化关系,将雷达信号划分为脉冲层、脉冲群组层、工作方式层三个层次;然后,借鉴生物体基因工程中蛋白质、DNA、基因片段的概念,类比对应雷达信号的不同层次信息,提出了雷达信号基因的概念和层次模型,建立了雷达信号层次处理的研究框架;最后,针对当前新体制雷达的典型信号,给出了雷达信号脉内基因的表征实例。     

多媒体通信网与数字电视网性能需求的探讨

重点讨论在有线电视宽带综合信息网络中，多媒体通信和数字电视系统涉及到的关键网络性能和参数，以及它们在数字视频、音频信号传输中所起的重要作用，深入探讨多媒体通信和数字电视系统的性能需求，同时指出作为有线电视宽带综合信息网络设计基础的重要性。     

A label-free biosensor based on organic transistors by using the interaction of mercapto DNA and gold electrodes

Organic thin-film transistors (OTFTs) with Au electrodes were successfully used as transducers for label-free deoxyribonucleic acid (DNA) sensors. Single-strand DNA (ssDNA), perfectly-matched double-strand DNA (dsDNA) and mis-matched DNA were immobilized on the surface of the source/drain electrodes of three OTFT devices respectively. The ssDNA molecules with mercapto group (–SH) can be well immobilized on the surface of Au electrode by chemical bond between –SH and Au atom. According to the significant difference in channel current, which was attributed to the changed contact resistances by introducing different DNA molecules on Au electrode, ssDNA, matched-dsDNA and mismatched-dsDNA were differentiated successfully in the experiments. The results may provide a promising approach for detecting DNA specificity and hybridization with label-free.     

Dimensionality Concept in Solid‐State Reactions: A Way to Control Synthesis of Functional Materials at the Nanoscale

The concept of dimensionality is fundamental in physics, chemistry, materials science, etc. Low‐dimensional and layered materials are distinguished by their unique physical properties and applications. Concurrently, low‐dimensional reactants, products, and reaction spaces extend the toolbox of materials science considerably. Here, the concept of dimensionality is adapted to solid‐state reactions by counting the basic axes along which the unit cell undergoes significant expansion/shrinking. For illustration, 1D synthesis of layered ternary compounds MA₂X₂ via derivatives of 2D‐Xenes, silicene, and germanene, is demonstrated, and the reaction mechanism and the role of templates are determined. The approach is then extended to 1D synthesis of non‐layered compounds. The 1D nature of the reactions, established with structural studies, is explored by nanoscale confinement. The mutual orientation of the reaction and confinement—parallel (thus preventing the lattice expansion) or orthogonal—controls the reaction pathways and outcome. The work provides a proof‐of‐concept for anisotropic reactivity caused by directional confinement.     

Explaining the Formation of Online News Startups in France and the United States: A Field Analysis

This article examines the differential formation of online news startups in Toulouse, France, and Seattle, United States. While Seattle is home to many startups, in Toulouse there have been just 4—and only 1 continues publishing. Drawing on Bourdieu's field theory, we argue that amount and types of capital held by journalists in the 2 cities varied as a result of differences in journalism's position in the field of power. These differences shaped the extent of startup formation in each city and structured journalists' capacities to convert their capital into the resources needed to form startups (e.g., funding, credentials, partnerships). These findings are positioned in relation to literatures on journalism innovation and comparative media.