High‐Performance n‐Channel Organic Transistors Using High‐Molecular‐Weight Electron‐Deficient Copolymers and Amine‐Tailed Self‐Assembled Monolayers

While high‐performance p‐type semiconducting polymers are widely reported, their n‐type counterparts are still rare in terms of quantity and quality. Here, an improved Stille polymerization protocol using chlorobenzene as the solvent and palladium(0)/copper(I) as the catalyst is developed to synthesize high‐quality n‐type polymers with number‐average molecular weight up to 10⁵ g mol^?1. Furthermore, by sp²‐nitrogen atoms (sp²‐N) substitution, three new n‐type polymers, namely, pBTTz, pPPT, and pSNT, are synthesized, and the effect of different sp²‐N substitution positions on the device performances is studied for the first time. It is found that the incorporation of sp²‐N into the acceptor units rather than the donor units results in superior crystalline microstructures and higher electron mobilities. Furthermore, an amine‐tailed self‐assembled monolayer (SAM) is smoothly formed on a Si/SiO₂ substrate by a simple spin‐coating technique, which can facilitate the accumulation of electrons and lead to more perfect unipolar n‐type transistor performances. Therefore, a remarkably high unipolar electron mobility up to 5.35 cm² V^?1 s^?1 with a low threshold voltage (≈1 V) and high on/off current ratio of ≈10⁷ is demonstrated for the pSNT‐based devices, which are among the highest values for unipolar n‐type semiconducting polymers.     

A Polymer Encapsulation Strategy to Synthesize Porous Nitrogen‐Doped Carbon‐Nanosphere‐Supported Metal Isolated‐Single‐Atomic‐Site Catalysts

A novel polymer encapsulation strategy to synthesize metal isolated‐single‐atomic‐site (ISAS) catalysts supported by porous nitrogen‐doped carbon nanospheres is reported. First, metal precursors are encapsulated in situ by polymers through polymerization; then, metal ISASs are created within the polymer‐derived p‐CN nanospheres by controlled pyrolysis at high temperature (200–900 °C). Transmission electron microscopy and N₂ sorption results reveal this material to exhibit a nanospheric morphology, a high surface area (≈380 m² g^?1), and a porous structure (with micropores and mesopores). Characterization by aberration‐corrected high‐angle annular dark‐field scanning transmission electron microscopy and X‐ray absorption fine structure confirms the metal to be present as metal ISASs. This methodology is applicable to both noble and nonprecious metals (M‐ISAS/p‐CN, M = Co, Ni, Cu, Mn, Pd, etc.). In particular, the Co‐ISAS/p‐CN nanospheres obtained using this method show comparable (E_1/2 = 0.838 V) electrochemical oxygen reduction activity to commercial Pt/C with 20 wt% Pt loading (E_1/2 = 0.834 V) in alkaline media, superior methanol tolerance, and outstanding stability, even after 5000 cycles.     

Ultrahigh Photocatalytic Rate at a Single‐Metal‐Atom‐Oxide

Metal oxides, as one of the mostly abundant and widely utilized materials, are extensively investigated and applied in environmental remediation and protection, and in energy conversion and storage. Most of these diverse applications are the result of a large diversity of the electronic states of metal oxides. Noticeably, however, many metal oxides present obstacles for applications in catalysis, mainly due to the lack of efficient active sites with desired electronic states. Here, the fabrication of single‐tungsten‐atom‐oxide (STAO) is demonstrated, in which the metal oxide's volume reaches its minimum as a unit cell. The catalytic mechanism in the STAO is determined by a new single‐site physics mechanism, named as quasi‐atom physics. The photogenerated electron transfer process is enabled by an electron in the spin‐up channel excited from the highest occupied molecular orbital to the lowest unoccupied molecular orbital +1 state, which can only occur in STAO with W⁵⁺. STAO results in a record‐high and stable sunlight photocatalytic degradation rate of 0.24 s^?1, which exceeds the rates of available photocatalysts by two orders of magnitude. The fabrication of STAO and its unique quasi‐atom photocatalytic mechanism lays new ground for achieving novel physical and chemical properties using single‐metal‐atom oxides (SMAO).     

Schleifbearbeitung von Hart‐Weich‐Verbunden – Finite‐Elemente‐Simulation des Schleifprozesses von hybriden Schichtverbunden

Grinding of ceramic‐metal‐compounds – finite element analysis simulation of the grinding process of hybrid stratified compounds In this paper, the subproject TP 8 “Grinding of ceramic‐metal‐compounds” is been introduced. An adapted grinding strategy should be created for the production of a ceramic‐cemented carbide compound drill. This aim should be obtained with experimental analysis and the use of finite element analysis to simulate the grinding process of ceramic‐cemented carbide compound drill. Furthermore a basic approach for simulating the grinding process of hybrid stratified compounds is been presented, which should be a basis for a finite element analysis simulation of a grinding process of ceramic‐cemented carbide compound drill.     

Microfluidic Skin‐on‐a‐Chip Models: Toward Biomimetic Artificial Skin

The role of skin in the human body is indispensable, serving as a barrier, moderating homeostatic balance, and representing a pronounced endpoint for cosmetics and pharmaceuticals. Despite the extensive achievements of in vitro skin models, they do not recapitulate the complexity of human skin; thus, there remains a dependence on animal models during preclinical drug trials, resulting in expensive drug development with high failure rates. By imparting a fine control over the microenvironment and inducing relevant mechanical cues, skin‐on‐a‐chip (SoC) models have circumvented the limitations of conventional cell studies. Enhanced barrier properties, vascularization, and improved phenotypic differentiation have been achieved by SoC models; however, the successful inclusion of appendages such as hair follicles and sweat glands and pigmentation relevance have yet to be realized. The present Review collates the progress of SoC platforms with a focus on their fabrication and the incorporation of mechanical cues, sensors, and blood vessels.     

Scaffold‐Free Liver‐On‐A‐Chip with Multiscale Organotypic Cultures

The considerable advances that have been made in the development of organotypic cultures have failed to overcome the challenges of expressing tissue‐specific functions and complexities, especially for organs that require multitasking and complex biological processes, such as the liver. Primary liver cells are ideal biological building blocks for functional organotypic reconstruction, but are limited by their rapid loss of physiological integrity in vitro. Here the concept of lattice growth used in material science is applied to develop a tissue incubator, which provides physiological cues and controls the 3D assembly of primary cells. The cues include a biological growing template, spatial coculture, biomimetic radial flow, and circulation in a scaffold‐free condition. The feasibility of recapitulating a multiscale physiological structural hierarchy, complex drug clearance, and zonal physiology from the cell to tissue level in long‐term cultured liver‐on‐a‐chip is demonstrated. These methods are promising for future applications in pharmacodynamics and personal medicine.     

Platelet‐to‐lymphocyte ratio better predicts inflammation than neutrophil‐to‐lymphocyte ratio in end‐stage renal disease patients

Neutrophil‐to‐lymphocyte ratio (NLR) was introduced as a potential marker to determine inflammation in end‐stage renal disease (ESRD) patients. Recently, platelet‐to‐lymphocyte ratio (PLR) and NLR were found to positively correlated with inflammatory markers including tumor necrosis factor‐α (TNF‐α) and interleukin (IL)‐6 in cardiac and noncardiac patients. Data regarding PLR and its association with inflammation are lacking in hemodialysis (HD) and peritoneal dialysis (PD) patients. Hence, we aimed to determine the relationship between PLR, NLR, and inflammation in ESRD patients. This was a cross‐sectional study involving 62 ESRD patients (29 females, 33 males; mean age, 49.6 ± 14.6 years) receiving PD or HD for ≥6 months in the Dialysis Unit of Necmettin Erbakan University. PLR, NLR, C‐reactive protein, TNF‐α, IL‐6 levels were measured. PLR, NLR, serum high sensitive C‐reactive protein, IL‐6, and TNF‐α levels were significantly higher in PD patients when compared with HD patients. ESRD patients with PLR ≥ 140 had significantly higher NLR, IL‐6, and TNF‐α levels when compared to patients with PLR < 139. In the bivariate correlation analysis, PLR was positively correlated with NLR, IL‐6, and TNF‐α in this population. When we compared the association of PLR and NLR with IL‐6 (r = 0.371, P = 0.003 vs. r = 0.263, P = 0.04, respectively) and TNF‐α (r = 0.334, P = 0.008 vs. r = 0.273, P = 0.032, respectively), PLR was found to be superior to NLR in terms of inflammation in ESRD patients. Simple calculation of PLR can predict inflammation better than NLR in ESRD patients.     

Biotinylated Photopolymers for 3D‐Printed Unibody Lab‐on‐a‐Chip Optical Platforms

The present work reports the first demonstration of straightforward fabrication of monolithic unibody lab‐on‐a‐chip (ULOCs) integrating bioactive micrometric 3D scaffolds by means of multimaterial stereolithography (SL). To this end, a novel biotin‐conjugated photopolymer is successfully synthesized and optimally formulated to achieve high‐performance SL‐printing resolution, as demonstrated by the SL‐fabrication of biotinylated structures smaller than 100 µm. By optimizing a multimaterial single‐run SL‐based 3D‐printing process, such biotinylated microstructures are incorporated within perfusion microchambers whose excellent optical transparency enables real‐time optical microscopy analyses. Standard biotin‐binding assays confirm the existence of biotin‐heads on the surfaces of the embedded 3D microstructures and allow to demonstrate that the biofunctionality of biotin is not altered during the SL‐printing, thus making it exploitable for further conjugation with other biomolecules. As a step forward, an in‐line optical detection system is designed, prototyped via SL‐printing and serially connected to the perfusion microchambers through customized world‐to‐chip connectors. Such detection system is successfully employed to optically analyze the solution flowing out of the microchambers, thus enabling indirect quantification of the concentration of target interacting biomolecules. The successful application of this novel biofunctional photopolymer as SL‐material enables to greatly extend the versatility of SL to directly fabricate ULOCs with intrinsic biofunctionality.     

Sol‐gel derived C‐SiC composites for re‐entry structures

Composites of carbon fibers, fabrics, or their precursors as reinforcement, and sol‐gel‐derived silicon carbide as matrix, have been developed, aiming at high‐temperature stable ceramics that can be utilized for re‐entry structures. These composites are produced via the sol‐gel process, starting with a sol‐gel reaction of a mixture of silane precursors. The sol‐gel‐derived resin is cast onto the reinforcement fibers/fabrics mat (carbon or its precursors) to produce a ‘green’ composite that is being cured. The ‘green’ composite is converted into a C‐SiC composite via a gradual heat‐pressure process under inert atmosphere, during which the organic substituents on the silicon atoms undergo internal oxidative pyrolysis via the schematic reaction: (SiRO_3/2)_n → SiC + CO₂ + H₂O The composition of the resultant silicon‐oxi‐carbide is tailorable via modifying the composition of the sol‐gel reactants. The reinforcement, when made of carbon precursors, is converted into carbon during the heat‐and‐pressure processing as well. The C‐SiC composites thus derived exhibit superior thermal stability and comparable thermal conductivity, combined with good mechanical strength features and failure resistance, which render them greatly applicable for re‐entry shielding, heat‐exchange pipes, and the like.     

Quasi‐Solid‐State Single‐Atom Transistors

The single‐atom transistor represents a quantum electronic device at room temperature, allowing the switching of an electric current by the controlled and reversible relocation of one single atom within a metallic quantum point contact. So far, the device operates by applying a small voltage to a control electrode or “gate” within the aqueous electrolyte. Here, the operation of the atomic device in the quasi‐solid state is demonstrated. Gelation of pyrogenic silica transforms the electrolyte into the quasi‐solid state, exhibiting the cohesive properties of a solid and the diffusive properties of a liquid, preventing the leakage problem and avoiding the handling of a liquid system. The electrolyte is characterized by cyclic voltammetry, conductivity measurements, and rotation viscometry. Thus, a first demonstration of the single‐atom transistor operating in the quasi‐solid‐state is given. The silver single‐atom and atomic‐scale transistors in the quasi‐solid‐state allow bistable switching between zero and quantized conductance levels, which are integer multiples of the conductance quantum G₀ = 2e²/h. Source–drain currents ranging from 1 to 8 µA are applied in these experiments. Any obvious influence of the gelation of the aqueous electrolyte on the electron transport within the quantum point contact is not observed.     

In‐plane and out‐of‐plane constraint parameters along a three‐dimensional crack‐front stress field under creep loading

Full‐field three‐dimensional (3D) numerical analyses was performed to determine in‐plane and out‐of‐plane constraint effect on crack‐front stress fields under creep conditions of finite thickness boundary layer models and different specimen geometries. Several parameters are used to characterize constraint effects including the non‐singular T‐stresses, the local triaxiality parameter, the T_z ‐factor of the stress‐state in a 3D cracked body and the second‐order‐term amplitude factor. The constraint parameters are determined for centre‐cracked plate, three‐point bend specimen and compact tension specimen. Discrepancies in constraint parameter distribution on the line of crack extension and along crack front depending on the thickness of the specimens have been observed under different loading conditions of creeping power law hardening material for various configurations of specimens.