Sub‐ and Supramolecular X‐Ray Characterization of Engineered Tissues from Equine Tendon,Bovine Dermis,and Fish Skin Type‐I Collagen

Collagen represents one of the most widely used biomaterial for scaffolds fabrication in tissue engineering as it represents the mechanical support of natural tissues. It also provides physical scaffolding for cells and it influences their attachment, growth, and tissue regeneration. Among all fibrillary collagens, type I is considered one of the gold standard for scaffolds fabrication, thanks to its high biocompatibility, biodegradability, and hemostatic properties. It can be extracted by chemical and enzymatic protocols from several collagen‐rich tissues, such as tendon and skin, of different animal species. Both the extraction processes and the manufacturing protocols for scaffolds fabrication provide structural and mechanical changes that can be tuned in order to deeply impact the properties of the final biomaterial. The aim of this review is to discuss the role of X‐rays to study structural changes of type I collagen from fresh collagen‐rich tissues (bovine, equine, fish) to the final scaffolds, with the aim to screen across available collagen sources and scaffolds fabrication protocols to be used in tissue regeneration.     

Applications of Tamm plasmon-liquid crystal devices

ABSTRACT

The Tamm-plasmon-polariton (TPP) occurs at the interface between a metallic film and the photonic-crystal (PC) substrate. Unlike conventional surface-plasmon-polariton (SPP), TPP can be directly excited by both the transverse electric (TE) and transverse magnetic (TM) electromagnetic waves without using additional coupling optics. The fact that the optical functionality of most plasmonics devices is determined after fabrication limits their applications. Tunable SPP devices by applying liquid crystals (LCs) have been widely demonstrated due to their large birefringence and easy controllability via external stimuli. However, actively tuning TPP is difficult because the localised electric field is between the metallic film and PC substrate, the change of refractive index above the metallic film has only small influences on TPP. This article is intended to briefly review recent progress towards using LCs for actively tuning TPP devices. Not only TPP devices can gain benefits from LCs, we will also discuss the applications of TPP for measuring the anisotropy of the alignment films of LC devices. The sensitivity of the proposed scheme will be discussed.     

Advances of phononics in 2012—2022

Due to its great potential applications in thermal management, heat control, and quantum information, phononics has gained increasing attentions since the first publication in Rev. Mod. Phys. 84 1045 (2012). Many theoretical and experimental progresses have been achieved in the past decade. In this paper, we first give a critical review of the progress in thermal diodes and transistors, especially in classical regime. Then, we give a brief introduction to the new developing research directions such as topological phononics and quantum phononics. In the third part, we discuss the potential applications. Last but not least, we point out the outlook and challenges ahead.     

基于碳化硅衬底的宽禁带半导体外延

宽禁带半导体具备禁带宽度大、电子饱和飘移速度高、击穿场强大等优势,是制备高功率密度、高频率、低损耗电子器件的理想材料。碳化硅(SiC)材料具有热导率高、化学稳定性好、耐高温等优点,在SiC衬底上外延宽禁带半导体材料,对充分发挥宽禁带半导体材料的优势,并提升宽禁带半导体电子器件的性能具有重要意义。得益于SiC衬底质量持续提升及成本不断降低,基于SiC衬底的宽禁带半导体电子市场占比呈现逐年增加的态势。在SiC衬底上外延生长高质量的宽禁带半导体材料是提高宽禁带半导体电子器件性能及可靠性的关键瓶颈。本文综述了近年来国内外研究者们在SiC衬底上外延SiC、氮化镓(GaN)、氧化镓(Ga₂O₃)所取得的研究进展,并展望了SiC衬底上宽禁带半导体外延的发展及应用前景。     

Synthesis,Electrochemistry, and Photophysical Studies of Ruthenium(II) Polypyridine Complexes with D–π–A–π–D Type Ligands and Their Application Studies as Organic Memories

A new class of ruthenium(II) polypyridine complexes with a series of D–π–A–π–D type (D=donor, A=acceptor) ligands was synthesized and characterized by ¹H NMR spectroscopy, mass spectrometry, and elemental analysis. The photophysical and electrochemical properties of the complexes were also investigated. The newly synthesized ruthenium(II) polypyridine complexes were found to exhibit two intense absorption bands at both high‐energy (λ=333–369 nm) and low‐energy (λ=520–535 nm) regions. They are assigned as intraligand (IL) π→π* transitions of the bipyridine (bpy) and π‐conjugated bpy ligands, and IL charge‐transfer (CT) transitions from the donor to the acceptor moiety with mixing of dπ(Ru^II)→π*(bpy) and dπ(Ru^II)→π*(L) MLCT characters, respectively. In addition, all complexes were demonstrated to exhibit intense red emissions at approximately λ=727–744 nm in degassed dichloromethane at 298 K or in n‐butyronitrile glass at 77 K. Nanosecond transient absorption (TA) spectroscopy has also been carried out, establishing the presence of the charge‐separated state. In order to understand the electrochemical properties of the complexes, cyclic voltammetry has also been performed. Two quasi‐reversible oxidation couples and three quasi‐reversible reduction couples were observed. One of the ruthenium(II) complexes has been utilized in the fabrication of memory devices, in which an ON/OFF current ratio of over 10⁴ was obtained.     

Kinetic Buffers

This paper proposes a new type of molecular device that is able to act as an inverse proton sponge to slowly decrease the pH inside a reaction vessel. This makes the automatic monitoring of the concentration of pH‐sensitive systems possible. The device is a composite formed of an alkyl chloride, which kinetically produces acidity, and a buffer that thermodynamically modulates the variation in pH value. Profiles of pH versus time (pH–t plots) have been generated under various experimental conditions by computer simulation, and the device has been tested by carrying out automatic spectrophotometric titrations, without using an autoburette. To underline the wide variety of possible applications, this new system has been used to realize and monitor HCl uptake by a di‐copper(II) bistren complex in a single run, in a completely automatic experiment.     

Altering the Position of Phenyl Substitution to Adjust Film Morphology and Memory Device Performance

In this study, two structural isomers α‐PBT and β‐PBT, which only differ in the phenyl substituent position on the quinoline chromophore, have been designed and successfully synthesized. The influences of substituent position on the film morphology and the storage performance of the devices were investigated. Both molecules employed in the memory devices exhibited same nonvolatile binary (write‐once‐read‐many‐times; WORM) characteristics, but the switch threshold voltage (Vth) of the β‐PBT‐based device was clearly lower than that of the α‐PBT‐based device. Simulation results demonstrate that the variation of the phenyl substituent position led to different intermolecular stacking styles and thus to varied grain sizes for each film morphology. This work illustrates that altering the phenyl substituent position on the molecular backbone could improve the quality of the film morphology and reduce power consumption, which is good for the rational design of future advanced organic memory devices (OMDs).     

Photoluminescence properties of a cationic trinuclear zinc(II) complex with the tetradentate Schiff base ligand 6‐methyl‐2‐({[(pyridin‐2‐yl)methyl]imino}methyl)phenolate

Metal complexes with Schiff base ligands have been suggested as potential phosphors in electroluminescent devices. In the title complex, tetrakis[6‐methyl‐2‐({[(pyridin‐2‐yl)methyl]imino}methyl)phenolato‐1:2κ⁸N,N′,O:O;3:2κ⁸N,N′,O:O]trizinc(II) hexafluoridophosphate methanol monosolvate, [Zn₃(C₁₄H₁₃N₂O)₄](PF₆)₂·CH₃OH, the Zn^II cations adopt both six‐ and four‐coordinate geometries involving the N and O atoms of tetradentate 6‐methyl‐2‐({[(pyridin‐2‐yl)methyl]imino}methyl)phenolate ligands. Two terminal Zn^II cations adopt distorted octahedral geometries and the central Zn^II cation adopts a distorted tetrahedral geometry. The O atoms of the phenolate ligands bridge three Zn^II cations, forming a dicationic trinuclear metal cluster. The title complex exhibits a strong emission at 469 nm with a quantum yield of 15.5%.     

Reversible Mechanical Switching of Magnetic Interactions in a Molecular Shuttle

An acid–base switchable molecular shuttle based on a [2]rotaxane, incorporating stable radical units in both the ring and dumbbell components, is reported. The [2]rotaxane comprises a dibenzo[24]crown-8 ring (DB24C8) interlocked with a dumbbell component that possesses a dialkylammonium (NH₂⁺) and a 4,4′-bipyridinium (BPY²⁺) recognition site. Deprotonation of the rotaxane NH₂⁺ centers effects a quantitative displacement of the DB24C8 macroring to the BPY²⁺ recognition site, a process that can be reversed by acid treatment. Interaction between stable 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radicals connected to the ring and dumbbell components could be switched between noncoupled (three-line electron paramagnetic resonance (EPR) spectrum) and coupled (five-line EPR spectrum) upon displacement of the spin-labelled DB24C8 macroring. The complete base- and acid-induced switching cycle of the EPR pattern was repeated six times without an appreciable loss of signal, highlighting the reversibility of the process. Hence, this molecular machine is capable of switching on/off magnetic interactions by chemically driven reversible mechanical effects. A system of this kind represents an initial step towards a new generation of nanoscale magnetic switches that may be of interest for a variety of applications.     

Utilizing Paper-Based Devices for Antimicrobial-Resistant Bacteria Detection

Antimicrobial resistance (AMR), the ability of a bacterial species to resist the action of an antimicrobial drug, has been on the rise due to the widespread use of antimicrobial agents. Per the World Health Organization, AMR has an estimated annual cost of USD 34 billion in the US and is predicted to be the number one cause of death worldwide by 2050. One way AMR bacteria can spread, and by which individuals can contract AMR infections, is through contaminated water. Monitoring AMR bacteria in the environment currently requires that samples be transported to a central laboratory for slow and labor intensive tests. We have developed an inexpensive assay using paper-based analytical devices (PADs) that can test for the presence of β-lactamase-mediated resistance. To demonstrate viability, the PAD was used to detect β-lactam resistance in wastewater and sewage and identified resistance in individual bacterial species isolated from environmental water sources.