Rigid Matrix Research Articles

Exploiting the photophysical features of DMAN template in ITQ-51 zeotype in the search for FRET energy transfer.

The combination between photoactive molecules and inorganic structures is of great interest for the development of advanced materials in the field of optics. Particularly, zeotypes with extra-large pore size are attractive because they allow the encapsulation of bulky dyes. The microporous aluminophoshate Mg-ITQ-51 (IFO-type structure) represents an ideal candidate because of the synergic combination of two crucial features: the IFO framework itself, which is composed of non-interconnected one-dimensional extra-large elliptical channels with a diameter up to 11 Å able to host bulky guest species, and the particular organic structure-directing agent used for the synthesis (1,8-bis(dimethylamino)naphthalene, DMAN), which efficiently fills the IFO pores, and is itself a photoactive molecule with interesting fluorescence properties in the blue range of the visible spectrum, thus providing a densely-incorporated donor species for FRET processes. Besides, occlusion of DMAN dye in the framework triggers a notable improvement of its fluorescence properties by confinement effect. To extend the action of the material and to mimic processes such as photosynthesis in which FRET is essential, two robust laser dyes with bulky size, rhodamine 123 and Nile Blue, have been encapsulated for the first time in a zeolitic framework, together with DMAN, in a straightforward one-pot synthesis. Thus, photoactive systems with emission in the entire visible range have been achieved due to a partial FRET between organic chromophores protected in a rigid aluminophosphate matrix.

Quantification of the thermodynamic effects of the low-spin - high-spin interaction in molecular crystals of a mononuclear iron(II) spin crossover complex.

A method is proposed to estimate the energetic and entropic effects of spins of neighbouring molecules on the spin transition of a mononuclear spin crossover (SCO) complex in a molecular crystal. Density functional theory (DFT) methods have been used to model the SCO material [FeII(Lnpdtz)2(NCS)2] (Lnpdtz = 2-naphthyl-5-pyridyl-1,2,4-thiadiazole) exhibiting numerous π-π interactions using a 2D arrangement of 15 molecules. The modelling considers only the effects in the crystallographical ac plane with a particularly pronounced stacking but paves the way for future work with 3D arrangements which are computational much more costly. It involves the optimisation and normal mode calculation of the molecules in a rigid matrix of both low-spin (LS) and high-spin (HS) neighbours. This procedure has been used to calculate the previously defined cooperativity parameter Hcoop (S. Rackwitz, W. Klopper, V. Schünemann and J. A. Wolny, Phys. Chem. Chem. Phys., 2013, 15, 15450). For [FeII(Lnpdtz)2(NCS)] we obtain Hcoop = 11 kJ mol-1, a value which is comparable to those found for 3D polynuclear spin crossover materials. A normal mode analysis of the optimised centrally located molecule indicates that the vibrational entropy of the spin transition is somewhat higher (5 J K-1 mol-1) for the LS to HS transition in the LS matrix than in the HS one. The calculations show that the interactions with the neighbours influence the low-frequency modes with wave numbers <65-70 cm-1. These cause the main difference in the vibrational entropy of the spin transition for the vicinity of high- and low-spin molecules. Furthermore, a deformation of the coordination sphere of the central molecule is observed when the spins of the surrounding centres are switched. This deformation is accompanied by a change in the equatorial Fe-N bond lengths.

Competition between C-H⋯S and S-H⋯Cl H-bonds in a CHCl3-H2S complex: a combined matrix isolation IR spectroscopic and quantum chemical investigation.

H-bonded complexes between CHCl3 and H2S have been studied in a cold and inert argon matrix using IR spectroscopy. Both molecules were found to act as both a H-bond donor and acceptor, resulting in two different conformers. The more stable one (binding energy 3.25 kcal mol-1) was bound by a C-H⋯S H-bond, while the less stable one (1.90 kcal mol-1) by a S-H⋯Cl H-bond. The H-bonded complex formation has been confirmed by monitoring the spectral changes in νC-H and νS-H fundamental vibrations. The νC-H mode exhibited red shifts by 22.7 cm-1 upon C-H⋯S H-bond formation, while the formation of a S-H⋯Cl H-bond resulted in 24.2 and 25.4 cm-1 red shifts in the νS-H modes. The barrier for conversion of the less stable conformer to the more stable one was found to be 0.6 kcal mol-1. The rigid matrix environment prevented any detectable population transfer that required significant relative movement of the monomeric moieties. Dispersion interaction was found to significantly contribute to the overall stabilization of both conformers, more so for the S-H⋯Cl H-bonded one.

Effects of a liquid metal co‐filler on the properties of epoxy/binary filler composites

AbstractLiquid metals (LMs) with high fluidity and high thermal conductivity (TC) are receiving considerable attention in the research on thermal management polymer composites as alternatives to conventional rigid solid fillers or as co‐fillers to overcome the trade‐off between TC and composite processability at high filler loads. While most previous studies have investigated the effects of LM fillers in soft elastomeric matrices, their effects on the composite properties with rigid matrices, such as epoxy‐based polymers, have not been discussed extensively. Herein, we investigated the effects of LM eutectic Ga‐In (EGaIn) as a co‐filler on the properties of rigid epoxy‐based composites with a binary filler (Al2O3/EGaIn) system. The increase in the volume fraction of LM fillers significantly improves the processability of uncured precursor composites but markedly decreases the mechanical strength of the cured composites at their high loads—the latter effects have rarely been examined in previous studies. However, with adequate LM loads, the composites exhibited superior mechanical properties compared with the all‐solid‐filler system, withstanding a surprisingly high compressive load (~100 kN) under which the all‐solid‐filler system fractured. Furthermore, the epoxy/binary filler composites exhibited reasonably high TC values (~1 W/mK) comparable to that of commercial epoxy molding compounds, suggesting their potential applicability for electronic packaging.

The Springback Effect in Pre-Densified Sulfidic Solid Electrolyte/Binder-Sheets and Their Implication as Separators in All-Solid-State Batteries – a First Approach

All-solid-state batteries (ASSBs) are expected to revolutionize the Li-ion battery landscape thanks to multiple benefits, such as improving both intrinsic safety and potentially enabling high energy anode concepts.[1,2,3] Amongst the variety of possible solid electrolyte (SE) materials for ASSBs, sulfidic electrolytes are considered particularly advantageous, as they possess high ionic conductivities and beneficial mechanical plasticity, allowing their pre-densification by uniaxial cold pressing at high fabrication pressures (p fab).[4] However, one bottleneck of sulfidic ASSBs compared to conventional liquid-electrolyte batteries is the necessity of a certain operating pressure to provide/maintain an intimate mechanical contact between the various materials during materials characterization measurements (e.g., SE conductivity measurements) and/or battery cycling. For these, a special cell setup is required that is hermetically sealed and facilitates a defined and, ideally, variable application of different compressions (operating pressure, p oper) on the sample/cell stack.[5] Typically, ASSB characterization cells possess a defined circular geometry, whereby the components are placed in an inert polymer containment (e.g. a PEEK tube) and are electrically contacted via metal dies.[2,5,6] However, a problem which is often neglected in the literature is the poor solid-solid contact of pre-densified SE pellets (done at a high p fab) and mechanically hard current collector dies to contact the sample for impedance measurements. This leads to impedance artifacts and potentially inaccurately determined solid electrolyte Li+-ion conductivities (σ Li).[2] In this contribution, we firstly describe a novel ASSB cell setup enabling the artifact-free measurement of the ionic conductivity of pre-densified SE-binder sheets in rigid cell matrices. By applying this setup, we could decouple effects from fabrication pressure and operating pressure, providing the basis for determining the correlation between the SE separator porosity and its Li+-ion conductivity, comparing it to the correlations predicted by the Bruggeman equation.We use sheet-type separators consisting of Li6PS5Cl (LPSCl) solid electrolyte and different amounts and types of binder, such as hydrogenated nitrile butadiene rubber (HNBR) and polyisobutylene (PIB), prepared by a slurry-based process.[5] By means of potential-controlled electrochemical impedance spectroscopy (PEIS), the impact of different p fab and p oper on the Li+-ion conductivity of the LPSCl/binder-sheet separators are investigated. As a result, we show that densifying the SE separator sheets at a high p fab, resulting in a low residual porosity, can be used to increase their conductivity at lower p oper. However, a phenomenon which is not reported in such detail so far, is the sensitivity of the measured σ Li of pre-densified LPSCl/binder-sheet separators regarding the p oper. While for pure pre-densified SE powder pellets only a negligible sensitivity regarding the p oper was observed,[2] scalable pre-densified LPSCl/binder-sheet separators show a strong correlation between p oper and measured σ Li.The extent of this phenomenon can be traced back to a “springback” effect, wherby the release of pressure after fabrication a dense binder-sheet separator leads to an apparent decrease in conductivity. We found a clear trend between the binder amount and the extent of this springback effect in LPSCl/binder-sheets and how this affects σ Li at different p oper. Furthermore, to deepen the knowledge about this springback effect, we also investigated the extent of the springback effect on the type of binder (HNBR vs. PIB) and its molecular weight (PIB OPPANOL N50 vs. PIB OPPANOL N150).Additionally, to fully understand different contributions of the pressures and springback to the overall separator impedance, we used PEIS measurements at a very low temperature (-70°C) and a measurement cell with a negligible stray capacitance to clearly distinguish between SE bulk, grain boundary, and springback effects as well as contact resistances, in the impedance spectra for such LPSCl/binder-sheets.Lastly, we evaluate how the springback effect contributes to an overall full-cell impedance in LiNi0.6Co0.2Mn0.2O2|LiIn half-cells and provide a guideline to overcome contact resistances for pre-densified sheet-type ASSB cell components. Based on our findings, it can be concluded that the springback effect contributes to the overall impedance not only in pure SE impedance measurements, but also in half-cells and cannot be neglected when characterizing slurry-coated SE/binder separators-sheets.[1] J. Janek and W. G. Zeier, Nature Energy, 1, 16141, (2016).[2] J.-M. Doux et al., J. Mater. Chem. A, 8, 5049 (2020).[3] S. Cangaz et al., Adv. Energy Mater., 2001320 (2020).[4] Z. Deng et al., J. Electrochem. Soc., 163, A67 (2015).[5] C. Sedlmeier, T. Kutsch et al., J. Electrochem. Soc., 169, 070508, (2022).[6] W. Zhang et al. ACS Appl. Mater. Interfaces, 9, 17835 (2017). Acknowledgements: This work was carried out as part of the project "Industrialisierbarkeit Festkörperelektrolyte", funded by the Bavarian Ministry of Economic Affairs, Regional Development and Energy and also supported by the BMW Group.

(Invited) Progress in Polymer Electrolytes for Li° Electrode

The incentives for the use of lithium metal negative electrode are easily justified considering the gain in energy density. Polymer electrolytes disclosed almost fifty years ago are still considered as an option for the most thought-for all solid-state systems. In fact, the only solid-state batteries commercialised are those from Blue Solutions® powering busses in Europe, using a Li° negative, a PEO [poly(ethylene oxide)] matrix with a LiTFSI solute and an LiFePO4 cathode materials and operating at 70°C. 1500 -2000 cycles are routinely obtained. The main drawbacks of PEO, which is stable to lithium metal is a low conductivity at room temperature (10-5 - 10-6 Ohm-1.cm-1 at 25°C) while it reaches easily 10-3 - 10-4 Ohm-1.cm-1 at 70°C. The other impedimenta of PEO is the relatively low transference/transport number of the Li+ cation (T+ ≈ 0.2), resulting in the formation of a salt concentration gradient in the electrolyte upon operation, with concomitant polarisation and the triggering of dendrites when the Sand time is reached, shortening the cycle life-time. Other polymer matrices like poly(ε-caprolactone) PCL and poly(propylene carbonate) PPC show slightly better conductivity and higher transference number (T+ ≈ 0.5), but are not stable in contact with lithium metal.Our strategy to increase the conductivity at lower temperature consisted in modifying the polymer architecture, from linear (PEO) to comb polymer in which medium length PEG segments (Mw 1000 - 2000) are attached to the main backbone via a flexible non-solvating tether (PPO). This optimises the speed of re-orientation of the solvating units, speed needed to favour the ionic motion. With these polymers and delocalised salts like LiTFSI or LiFSI, conductivities close to 10-4 Ohm-1.cm-1 at 25°C are obtained though with the same transference number as PEO.In order to improve the selectivity of the cation transport in PEs, it is necessary to immobilise the negative charges of the salt by attaching them to a polymer or nano-particles. The other option consists in modifying the salt architecture to slow down the diffusion/migration of the anions by increasing the interactions of the anions with themselves or with the polymer backbone.We have found that, starting for a simple cellulose derivative, the action of FSO2N=C=O results in the attachment of anions to the backbone and that the poly(salts) are now able to form an alloy with PEO or other poly(ethers), with excellent mechanical properties imparted by the rigid cellulose matrix, yet giving Li-only conductivities allowing battery operation. Alternatively, SiO2 or Al2O3 nano-particles can be grafted with delocalised anionic moieties, which result, when dispersed into PEO, in conducting composites with again excellent electrochemical and mechanical properties.Modification of the well-known anion TFSI to increase its interactions and slow it down have been undertaken: either hydrogen bonds, dipole interactions, chain entanglement, or π - π interactions have been introduced in the RSO2N(-)SO2CF3 anion with R equal respectively CF2H—, (CH3)2N—, (CH3OC2H4)2N—, C6H5—. In all cases, higher T+ were obtained as compared with TFSI-, though the total conductivity was lower, but resulting still in σLi+ that translates into better lithium plating efficiencies as seen in the classical Li°/PE/Li° cycling tests and in batteries lifecycle.A final drawback of PEO is its inability to withstand voltages above 3.9 V vs. Li+:Li° while PPC for instance, stable to 4.5V, does decompose rapidly on the negative Li°. The obvious idea to combine a PEO based anolyte and a PPC catholyte stumbles on the consideration that PEO is far more solvating than PPC and deplete totally the polyester compartment, with no conductivity remaining. We solved this problem with the use of an immobilised polyanion in both the anolyte and catholyte, resulting in the stable operation of a Li°/NMC622 battery.All these research results will be discussed in details.

The microlayer model: A novel analytical homogenisation scheme for materials with rigid particles and deformable matrix - applied to simulate concrete

In the contribution at hand, a new material modelling approach is introduced. This formulation is based upon the Principle of Multiscale Virtual Power and consideration of micromechanically motivated assumptions. Consequently, the evolution of dissipative phenomena depends on the chosen microstructure. Therefore, a strong anisotropy, which is induced by damage, is represented even with isotropic material formulations. This phenomenon is present in concrete.Furthermore, the modelling approach is validated by different material tests. Tensile-tensile and compression-tensile tests are used for validation of the proposed description. Some material tests are taken from the existing literature, while others are presented in the contribution at hand. Furthermore, the capabilities of the proposed formulation to capture different amounts of textile reinforcement in concrete are shown by additional experiments from the literature. Subsequently, the consistent linearisation of the proposed model is verified based on numerical analyses.

Dopant-Matrix Afterglow Systems: Manipulation of Room-Temperature Phosphorescence/Thermally Activated Delayed Fluorescence Afterglow Mechanism via Mismatch/Match of Intermolecular Charge Transfer between Dopants and Matrices.

Dopant-matrix organic afterglow materials exhibit ease of fabrication and intriguing functions in diverse fields. However, a deep and comprehensive understanding of their photophysical behaviors remains elusive. Here we report manipulation of a room-temperature phosphorescence/thermally activated delayed fluorescence (RTP/TADF) afterglow mechanism via the mismatch/match of intermolecular charge transfer between dopants and matrices. When dispersed in inert crystalline matrices, the luminescent dopants show RTP lifetimes up to 2 s. Interestingly, when suitable organic matrices are selected, the resultant dopant-matrix materials display a TADF-type afterglow under ambient conditions due to the formation of dopant-matrix intermolecular charge transfer complexes. Detailed studies reveal that reverse intersystem crossing from dopants' T1 states to charge transfer complexes' S1 states, which features a moderate kRISC of 101-102 s-1, is responsible for the emergence of a TADF-type organic afterglow in rigid crystalline matrices. Such less reported delicate photophysics reveals a new aspect of the excited state property in dopant-matrix afterglow systems.

YAP1 Recognizes Inflammatory and Mechanical Cues to Exacerbate Benign Prostatic Hyperplasia via Promoting Cell Survival and Fibrosis.

Chronic prostatic inflammation promotes cell survival and fibrosis, leading to benign prostatic hyperplasia (BPH) with aggravated urinary symptoms. It is investigated whether yes-associated protein 1 (YAP1), an organ size controller and mechanical transductor, is implicated in inflammation-induced BPH. The correlation between YAP1 expression and fibrosis in human and rat BPH specimens is analyzed. Furthermore, the effects of YAP1 activation on prostatic cell survival and fibrosis, as well as the underlying mechanism, are also studied. As a result, total and nuclear YAP1 expression, along with downstream genes are significantly upregulated in inflammation-associated human and rat specimens. There is a significant positive correlation between YAP1 expression and the severity of fibrosis or clinical performance. YAP1 silencing suppresses cell survival by decreasing cell proliferation and increasing apoptosis, and alleviates fibrosis by reversing epithelial-mesenchymal transition (EMT) and extracellular matrix (ECM) deposition in prostatic BPH-1 and WPMY-1 cells. Mechanistically, inflammatory stimulus and rigid matrix stiffness synergistically activate the RhoA/ROCK1 pathway to provoke cytoskeleton remodeling, thereby promoting YAP1 activation to exacerbate BPH development. Overall, inflammation-triggered mechanical stiffness reinforcement activates the RhoA/ROCK1/F-actin/YAP1 axis, thereby promoting prostatic cell survival and fibrosis to accelerate BPH progression.

Ambient Phosphor with High Efficiency and Long Lifetime in Poly(Methyl Methacrylate) Through Charge-Transfer-Mediated Triplet Exciton Formation for Photolithography Applications.

Currently, purely organic compounds showing ambient phosphorescence with high efficiency (ΦP ) and ultra-long lifetime (τP ) are quite rare and often need to be achieved in hydrophilic poly(vinyl alcohol)-based hosts. This severely limits their applications. Here, we provide a solution to this issue by constructing an ortho-linked donor-acceptor (D-A) dyad whose D moiety has not only a long-lived T1 state to achieve a long τP , but also a Tn state that is close to the S1 state of the dyad to trigger effective spin-orbit charge transfer intersystem crossing (SOCT-ISC). The rationality of this strategy was validated by a new phosphor OF-BCz that is able to show a τP of 1.92 s and a ΦP of 30 % even in a less rigid matrix of poly(methyl methacrylate) (PMMA). Excitingly, OF-BCz exhibited its potential as both a photocuring initiator and an in situ quality indicator, allowing for the visual detection of defects in photolithographic patterning.

Ambient Phosphor with High Efficiency and Long Lifetime in Poly(Methyl Methacrylate) Through Charge‐Transfer‐Mediated Triplet Exciton Formation for Photolithography Applications

AbstractCurrently, purely organic compounds showing ambient phosphorescence with high efficiency (ΦP) and ultra‐long lifetime (τP) are quite rare and often need to be achieved in hydrophilic poly(vinyl alcohol)‐based hosts. This severely limits their applications. Here, we provide a solution to this issue by constructing an ortho‐linked donor‐acceptor (D−A) dyad whose D moiety has not only a long‐lived T1 state to achieve a long τP, but also a Tn state that is close to the S1 state of the dyad to trigger effective spin‐orbit charge transfer intersystem crossing (SOCT‐ISC). The rationality of this strategy was validated by a new phosphor OF‐BCz that is able to show a τP of 1.92 s and a ΦP of 30 % even in a less rigid matrix of poly(methyl methacrylate) (PMMA). Excitingly, OF‐BCz exhibited its potential as both a photocuring initiator and an in situ quality indicator, allowing for the visual detection of defects in photolithographic patterning.

Effect of the Graphene Quantum Dot Content on the Thermal, Dynamic-Mechanical, and Morphological Properties of Epoxy Resin.

Different amounts of graphene quantum dots (CQDs) (0, 1, 2.5, and 5 wt%) were incorporated into an epoxy matrix. The thermal conductivity, density, morphology, and dynamic mechanical thermal (DMTA) properties were reused from the study of Seibert et al.. The Pearson plot showed a high correlation between mass loading, thermal conductivity, and thermal diffusivity. A poorer correlation with density and heat capacity was observed. At lower CQD concentrations (0.1 wt%), the fracture surface showed to be more heterogeneous, while at higher amounts (2.5 and 5 wt%), a more homogeneous surface was observed. The storage modulus values did not change with the CQD amount. But the extension of the glassy plateau increased with higher CQD contents, with an increase of ~40 °C for the 5 wt% compared to the 2.5 wt% and almost twice compared to the neat epoxy. This result is attributed to the intrinsic characteristics of the filler. Additionally, lower energy dissipation and a higher glass transition temperature were observed with the CQD amount. The novelty and importance are related to the fact that for more rigid matrices (corroborated with the literature), the mechanical properties did not change, because the polymer bridging mechanism was not present, in spite of the excellent CQD dispersion as well as the filler amount. On the other hand, thermal conductivity is directly related to particle size and dispersion.

Developing Bright Afterglow Materials via Manipulation of Higher Triplet Excited States and Relay Synthesis in Difluoroboron β‐Diketonate Systems

AbstractAfterglow brightness represents one of the most important characteristics in the application of afterglow materials. High molar absorption coefficient, high afterglow efficiency, and long afterglow lifetimes are required to achieve intense afterglow. However, current strategies cannot simultaneously fulfill these requirements due to specific intrinsic problems. Here, based on the understanding of difluoroboron β‐diketonate systems, the manipulation of higher triplet excited states is conceived to selectively enhance intersystem crossing with phosphorescence lifetimes remaining long. Aromatic substrates, which possess specific HOMO levels and T1 levels, are selected for relay synthesis to form difluoroboron β‐diketonate compounds with very close‐lying S1 and T2 levels; according to the energy gap law, such systems exhibit strong intersystem crossing. Upon doping into rigid matrices, the resultant difluoroboron β‐diketonate systems display the brightest ambient afterglow that has ever been observed.

High‐Brightness, Hundred‐Second Level Ultralong Afterglow Polymers Built via Ultrasound‐Synchronized B‐O‐Click Strategy

AbstractIn recent years, there has been a growing interest in pure organic materials with ultralong room temperature phosphorescence (RTP) and afterglow duration time (tag) in the range of second level. However, it is extremely difficult to achieve tag &gt;60 s in the polymer fields. Herein, this work proposes a highly versatile ultrasound‐synchronized B‐O‐Click strategy that can firmly immobilize various types of polycyclic aromatic boronic acids (PABAs) as single‐molecular states in a tight and rigid matrix of poly(vinyl alcohol) (PVA), achieving a series of record‐breaking ultralong afterglow polymeric RTP materials. Based on this approach, a polymeric material is reported exhibiting a record‐breaking tag = 130 s, accompanied with an ultralong lifetime of 7.24 s and a good phosphorescence efficiency of 14.26%. Three other polymeric materials with tag over 60 s are also realized via the same strategy by changing the phosphor. In addition, record‐breaking ultralong green (tag = 115 s) and red (tag = 80 s) afterglow are further achieved based on the phosphorescence resonance energy transfer (PRET) effect.

Vertical musculocutaneous trapezius flap for the closure of postpneumonectomy empyema.

The aim of the study was to present our experience with the vertical musculocutaneous trapezius (VMCT) flap and highlight its utility in the thoracic wall reconstruction in patients with bronchopleural fistula (BPF). We present a five case series of patients with long-standing cavities and BPF. The VMCT flap was used, and a direct pathway into the defect was made through a separate posterior thoracotomy shortening the distance between the flap and the defect. In 80% of the cases, the flap succeeded in solving the fistula and filling the defect, quality of life improved, and the need for oxygen decreased. Management of open window thoracostomy is challenging. Debridement, thoracoplasty, and flap coverage are the mainstream of their treatment, but these patients have scarce available muscle. The VMCT flap represents the major non-affected musculocutaneous unit in the thoracic area after lung surgery. Its dermal component offers a rigid matrix to form a seal over the bronchial stump. Its muscular component adds a good amount of vascularized tissue. No functional impairment has been described after its use.

Reblooming of the cis-Bis(2-phenylpyridine) Platinum(II) Complex: Synthesis Updating, Aggregation-Induced Emission, Electroluminescence, and Cell Imaging.

Studies on the syntheses, photophysical properties, and applications of cis-bis(2-phenylpyridine) platinum(II) complex (Pt(ppy)2) family are of great importance, but very limited progress has been achieved to date. Herein, a one-pot method was established for the syntheses of Pt(ppy)2-type complexes Pt-ppy and Pt-tBu. These two compounds were nonemissive in dilute solutions. However, they produced intense red and deep-red phosphorescence in the aggregation and film states, with lifetimes and quantum yields up to 1.92 μs and 70%, respectively, exhibiting unique aggregation-induced emission (AIE) characteristics. According to the experimental and theoretical studies, molecular configuration transformation (MCT) in the excited state may occur because of the d-d transition from the Pt center, causing nonradiative transitions in the solution. Nevertheless, the MCT would be largely restricted by the intermolecular interactions or rigid matrix, thereby enabling efficient phosphorescence in the aggregation state and in the PMMA films. Consequently, the AIE characteristics of Pt-ppy and Pt-tBu probably result from the restriction of molecular configuration transformation (RMCT). Due to the π-π and/or weak Pt-Pt interactions and the concentration-dependent emission characteristics, they emit deep-red and NIR emissions generated by excimer and/or MMLCT emitting species. Inspired by their AIE features, electroluminescence and cell imaging applications are explored. To the best of our knowledge, this is the first comprehensive study on the synthesis optimization, photophysical properties, AIE characteristics, and applications of the Pt(ppy)2-type complexes, which may rebloom the research studies on this type of Pt(II) complex family and provide valuable insights on the development of phosphorescent AIE metal-organic complexes.

Magnetic training of the soft magnetorheological elastomers

The effect of repetitive quasi-static magnetisation of a magnetorheological elastomer on its magnetic response is discussed. Typical components of this material, namely soft silicone rubber and carbonyl iron powder, are used to produce magnetically sensitive composite samples. The composite specimens are examined by vibrating sample magnetometry. The influence of the elasticity of the composite matrix on the change in magnetic differential susceptibility of the material as a function of the number of repeated magnetisation cycles is evaluated. The soft matrix elastomers are characterised by the presence of maxima in the initial part of the differential susceptibility curves. The sample magnetisation values corresponding to such maxima vary with the number of magnetisation cycles. In addition, the initial magnetic susceptibility curves of soft samples obtained at different polarity of the applied field are not symmetrical. Symmetry is obtained by performing several subsequent magnetisation cycles. The differential susceptibility curves are affected by both reversible and irreversible processes related to particle mobility in the matrix. The magnetic response of composite samples with rigid matrices is more similar to that of classical soft magnetic materials.

Rapid fractionation of noncondensed lignin from birch via acidified LiCl molten salt hydrates

The conventional fractionation of lignocellulose is generally carried out at high temperatures, high acid or alkali, or using organic solvents due to the rigid matrix of lignocellulose and crystallinity of cellulose, leading to the condensation of lignin and environmental pollution, and hindering the further value-added utilization of lignin. In this work, a rapid fractionation method was proposed, in which hemicellulose and cellulose (holocellulose) were first dissolved and partially hydrolyzed in acidified LiCl molten salt hydrates, followed by a filtration process to isolate the lignin solid with a purity of 88.3%. It was found that the dissolution of holocellulose required the addition of a small amount of acid to break the cellulose chain into short chains. Due to the small amount of acid added and the rapid dissolution, the obtained lignin has as high as 89.5% of β-O-4 bond content close to the theoretical value, suggesting that a promising native lignin structure was preserved. The isolated lignin can be selectively depolymerized into monophenol over Ru/C catalyst with a high yield of 24.2%. In addition, the dissolved holocellulose without containing lignin was selectively hydrolyzed into sugars in acidified LiCl molten salt hydrates, giving 63.1% of xylose, 43.9% of glucose, 29.5% of xylan oligomers, and 48.2% of glucan oligomers, respectively.

Endowing Carbon Dots with Long‐Lived Phosphorescence Emission in Aqueous Solutions

AbstractRoom temperature phosphorescent carbon dots (RTP CDs) have received increasing attention in recent years due to their outstanding optical properties and potential applications. It is worth noting that RTP CDs in aqueous solution have inspired special interests because of their low toxicity, long lifetime, and ability to avoid autofluorescence and background fluorescence, exhibiting wide application prospects in time‐resolved biological imaging and sensing. However, achieving phosphorescent CDs in aqueous solutions remains a considerable challenge because water molecules and oxygen can cause the deactivation of triplet‐state excitons, resulting in phosphorescence quenching. Several strategies have been proposed to counter the problem including encapsulated CDs in a rigid matrix, hydrogen bonding, and covalent bonding fixation. Consequently, a more significant number of RTP CDs materials with excellent optical stability, long lifetime, and multicolor are successfully obtained. Herein, the recent development of RTP CDs materials in aqueous solution as well as the corresponding fabricated strategies and luminescence mechanism is detailly summarized and reviewed. Furthermore, various applications of water‐phase RTP CDs materials in information security, sensing, bioimaging, light‐emitting diodes, and fingerprinting are also discussed. Finally, an outlook on the development of CDs materials and applications is proposed.

The cell volume-regulatory glycine transporter GLYT1 is activated following metallopeptidase-mediated detachment of the oocyte from the zona pellucida.

Independent cell volume regulation is first acquired by the oocyte in two steps that occur during meiotic maturation: (1) activation of the glycine transporter GLYT1 (Slc6a9) that mediates the intracellular accumulation of glycine to provide osmotic support in the mature egg and early preimplantation embryo, and (2) release of the oocyte from the strong attachment to its rigid extracellular matrix shell, the zona pellucida (ZP). It was recently shown that oocyte-ZP detachment requires metallopeptidase activity that is proposed to cleave transmembrane ZP proteins connecting the oocyte to the ZP. It is unknown, however, how GLYT1 is activated. We hypothesized that oocyte-ZP detachment precedes and may be required for GLYT1 activation. In identically treated pools of oocytes, oocyte-ZP detachment occurred ~20 min before GLYT1 activation. In individual oocytes, GLYT1 activity was detected only in those that were mostly or fully detached. Blocking detachment using previously validated small molecule metallopeptidase inhibitors partly suppressed GLYT1 activation. However, removal of the ZP did not accelerate GLYT1 activation. This indicates that oocyte-ZP detachment or cleavage of transmembrane ZP proteins may be required for GLYT1 to become fully activated, or alternatively that metallopeptidase activity independently affects both detachment and GLYT1 activation.