Secondary Donor Research Articles

Dihydro‐1H‐Pyrazoles as Donor Blocks in Donor–Acceptor Chromophores for Electro‐Optics: A DFT Study of Hyperpolaizability and Electronic Excitations

ABSTRACTA diverse set of promising donors for donor–acceptor chromophores based on dihydro‐1H‐pyrazole (pyrazoline) for use in electro‐optics was investigated using DFT at M06‐2X/aug‐cc‐pVDZ level of theory. These calculations showed that it is possible to achieve a molecular hyperpolarizability of up to 1700*10−30 esu (up to three times higher compared to conventional diethylaniline donors) for a simple tricyanofuran‐based acceptor by carefully tuning the donor structure. It was shown that the molecular hyperpolarizability is mainly affected by the substituents in the aryl rings in positions 3 and 1 of the pyrazoline cycle, while the substituents of the aryl ring in position 5 and the pyrazoline ring itself can be varied without significant effects on the hyperpolarizability. For one of the compounds, a detailed study of the lowest energy electronic excitation was performed using the TD‐DFT, confirming the role of the pyrazoline ring as a secondary donor.

Investigation of heterocyclic azo dyes for dye-sensitized solar cells and non-linear optical properties: Synthesis and in-silico studies

Four thiophene-based donor-π-azo-acceptor dyes were designed and synthesized with benzoic and salicylic acids anchoring groups for dye-sensitized solar cells (DSSC). The results show that the orientation of the secondary donor significantly affects molecular planarity, which in turn affects the characteristics of charge transfer (CT) inside the backbones of thiophene-azo-benzoic or salicylic acids. These results have been confirmed by the time-dependent density functional theory (TD-DFT) study, which shows that the dyes' vertical absorption maximum increases as the secondary donors' providing strength increases. Photovoltaic parameters indicate an increase in DSSC performance from PG9 to PG12. Moreover, dye@TiO2 cluster investigations suggest that these dyes could combine with TiO2 to cause dye@TiO2 cluster absorbance to shift red.The synthesis of PG9 to PG12 confirms theoretical predictions, with initial absorption in dimethylformamide (DMF) and energies of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) following a pattern like that seen in density functional theory (DFT) investigations. According to TGA data, PG9 to PG12 have exceptional thermal stability, making them suitable for DSSCs. The built-in DSSCs had varying efficiencies; PG10 had the highest efficiency at 4.73 ± 0.1, and PG12 had the lowest at 1.72 ± 0.1. According to the theoretical and practical DSSC results, secondary donors are essential in defining molecular properties and device performance.

Tuning the push-pull dyes: Construction of polarity insensitive probes for G4 DNA

We report here the design and synthesis of two new polarity-insensitive push-pull dyes TCP-SO3 and TCP-COOH and developed as fluorescent probes for G-quadruplex (G4) DNAs. The strategy involved in this study is to use the traditional D-π-A building block of carbazole-pyridinium (CP), while introducing of a diphenylimidazole group as a secondary donor as well as molecular rotor to form the D-D-π-A configuration, thus ascertaining the effect of the auxiliary group on the photophysics of the dyes. Additionally, N-sulfobutylpyridinium and N-(carboxyethyl) pyridinium bromide moieties are employed as electron-withdrawing anchoring groups, respectively, due to their hydrophilicity and electronic characters, thereby regulating the G4 DNA binding affinity and photophysical properties. It was found that the introduction of diphenylimidazole group to form the D-D-π-A configuration brought superior performance, in terms of polarity-insensitive property with a fluorescence-off state in various polarity solvents. Both dyes exhibited a clear-cut off-on sensing preference for G4 over non-G4 DNA structures, dye TCP-SO3 having a hydrophilic sulfonate group at electron-acceptor part displayed superior G4 DNA binding and selectivity compared to TCP-COOH with a carboxylic acid group. Detailed investigation on the relationship between the structure, photophysical properties, and G4 DNA sensing performance was described.

The role of secondary donor in thiophene-based azo dyes for dye-sensitized solar cells and non-linear optics

The effect of altering the donating strength of secondary donors at the 4th position of the thiophene ring in a series of dyes labeled AB1 to AB9 is investigated in this study. According to the findings, the orientation of the secondary donor has a considerable impact on molecular planarity, resulting in changes in charge transfer (CT) properties within the thiophene-azo-benzoic acid backbone. The time-dependent density functional theory (TD-DFT) study supports these findings, indicating that the vertical absorption maximum of the dyes increases with the secondary donor's donating strength. From AB1 to AB5, photovoltaic parameters show an increase in DSSC performance. Furthermore, dye@TiO2 cluster experiments suggest the possibility of these dyes interacting with TiO2, resulting in red-shifted absorbance of dye@TiO2 clusters.Theoretical predictions are confirmed by the synthesis of AB1 to AB4, with initial absorption in dimethylformamide (DMF) and energies of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) following a similar pattern as observed in density functional theory (DFT) studies. TGA results show that AB1 to AB4 have remarkable thermal stability, enabling their practical application in DSSCs. The efficiencies of the constructed DSSCs varied, with AB4 having the highest (1.90 ± 0.1) and AB1 having the lowest (1.29 ± 0.1). Secondary donors play a critical role in determining molecular characteristics and device performance, according to the theoretical and experimental DSSC results.

Synergistic Modulation of Excited State Ingredients and Chiroptical Activity for High‐Performance Pure‐Green Circularly Polarized Electroluminescence

AbstractThe integration of chiral elements within a multiple resonance (MR) motif affords a prospective avenue to construct satisfying emitters tailored for state‐of‐the‐art circularly polarized organic light–emitting diodes (CP‐OLEDs). However, the concurrently realizing of both high luminescence efficiency and favorable dissymmetry factors (gPL) still remains a formidable challenge, particularly when aligning with the requirement of high color purity. Herein, a dual‐pronged approach is proposed to reconcile such trade‐offs by directly fusing a secondary chiral donor onto the MR scaffold, thereby facilitating a hybrid short/long‐range charge‐transfer with fine‐tuned compositions. Theoretical calculations unveil the pronounced impact of the chiral donor on meticulously refining the characteristics of excited states, therefore yielding a considerable gPL of 3.3 × 10−3, along with a high fluorescence quantum yield of 0.97, and a rapid reverse intersystem crossing rate of 3.06 × 105 s−1 in one embodiment. Leveraging these merits, electroluminescence devices incorporating them as chiral dopants exhibit exceptional performance, showcasing a peak external quantum efficiency of 36.6% and remarkable Commission Internationale de L'Eclairage coordinates of (0.19, 0.71), which represent one of the most notable achievements among pure‐green CP‐OLEDs.

Long-lived photoinduced charge separation in adamantane-bridged donor-acceptor dyads: A case of adamantane bridge conferring orthogonal donor-acceptor orientation and restricted rotation

Design of compact donor-acceptor dyads that can exhibit charge separated (CS) state lifetimes extending to the microsecond time domain remains a major challenge even today. A simple but effective design strategy that can lead to long CS state lifetimes, in at least a few compact dyads, is still elusive. Herein we propose that use of adamantane (AD) as bridge can enhance CS state lifetimes in small molecule donor-acceptor dyads. This paper reports AD-bridged dyads, AN-AD-NB and PY-AD-NB, wherein the anthracene (or pyrene) donor and nitrobenzene acceptor are attached to bridgehead positions of AD. The singlet CS states generated upon irradiation were long-lived (lifetimes >1 μs) and decayed to the ground and local triplet states, simultaneously. Electron transfer reactions of the CS state with secondary donor and acceptor established that the CS state is sufficiently long-lived to participate in intermolecular reactions. X-ray crystal structure of the AN-AD-NB dyad reveals that the donor and acceptor are orthogonally oriented, which reduces the donor-acceptor interaction, and thereby the charge recombination rate, significantly. By analysing the X-ray structure, we predict that all adamantane-bridged compact dyads will have orthogonal donor-acceptor orientation and exhibit long-lived CS states. We also report studies with bisadamantyl-substituted dyads and the results confirmed that the local triplets are formed from the CS state through hyperfine interaction. Based on our work we propose that the hyperfine interaction, which is not expected to occur in compact dyads because of the short donor-acceptor separation, can indeed occur if the CS state is sufficiently long-lived.

Negative comonomer effect induced by TiCl3-like clusters in MgCl2-based Ziegler-Natta catalysts

The comonomer effect of ethylene/α-olefin copolymerization in the Ziegler-Natta (Z-N) catalytic system, remaining largely elusive and less understood at the molecular level, has been of huge industrial importance and absorbing research interest for decades. Herein, four catalysts with similar physical structures but different polymerization activities and comonomer effects were synthesized by using n-butanol in combination with different secondary electron donors. By tracking catalyst formation, it was found that altering the secondary donor changes the ν(O-H) stability and in turn the MgCl2 facet growth, to influence the polymerization activity. In situ diffuse reflectance Ultraviolet–visible spectra show that different types of active Ti centers are in function in the ethylene polymerization and the ethylene/1-butene copolymerization. Tracing further the microscopic structures of active species upon triethylaluminium (TEA) activation by using Extended X-ray Absorption Fine Structure, it is found that: (i) for the catalysts with negative comonomer effect, the enhanced donor migration promotes the aggregation of active species and leads to the formation of TiCl3-like clusters; (ii) by contrast, for the catalysts with positive comonomer effect, the less mobile donors hinder the aggregation of active species, thus inducing the formation of isolated Ti3+ sites. Our work reveals an evident correlation between the active center and the comonomer effect, which may be strongly modified by the aggregation of the former.

Tailoring the donor moieties in TPA‐based organic dyes for efficient photovoltaic, optical and nonlinear optical response properties

AbstractThe current study reports tailoring the electronic donor structures of organic dyes to modify their optical and nonlinear optical (NLO) response properties. Five (5) tri‐phenyl amine (TPA) based Donor‐π‐Acceptor (D‐π‐A) organic dyes with the codes ICAA1, ICAA2, ICAA3, ICAA4, and ICAA5 were designed and investigated for their optical and NLO properties using quantum chemical methods. Optical and NLO properties of these dyes were studied by CAM‐B3LYP method and 6‐311G* basis set. The focus has been on the impact of adding secondary donors and shifting their substitutions at ortho (o), meta (m) and para (p) positions. Among all designed compounds, ICAA4 showed the highest amplitude of average third‐order NLO polarizability <γ>, which is calculated to be 1316 × 10−36 esu. Time‐dependent Density Functional Theory (TD‐DFT) method was used to determine how a change in the position of the donor affected the excitation energy (Eg) and NLO response properties. The findings showed that changing the position of the secondary donor results in a red shift among absorption spectra as well as the increase in their NLO responses. Complete process of intramolecular charge transfer (ICT) has been investigated in terms of different optical parameters such as frontier molecular orbitals (FMOs), molecular electrostatic potentials (MEPs), transition density matrix (TDMs), density of states (DOS), electron density difference (EDD), and natural bond orbital (NBO) analysis. Our calculations for study of ICT process indicate that p‐position of methoxy group performs better among all other positions and even it has better NLO response properties than the compound with three collective methoxy groups. The calculated Voc values of all designed molecules range from 1.09 to 1.30, all of them are positive while their ΔGinject is found to be in the range of −0.87 to −1.79 eV indicating their decent potential for photovoltaic applications. The studied optical, NLO and photovoltaic parameters illustrated that ICAA1 to ICAA5 are appropriate molecules not only for NLO applications but also for efficient photovoltaic purposes.

Biomechanical analysis of tendon turnover tenorrhaphy compared to direct repair and Pulvertaft weave.

The aim of the present study was to evaluate biomechanical properties of tendon turnover repair in comparison to direct repair and Pulvertaft weave. A total of 48 sheep flexor tendons were assigned to eight groups comprising single or double tendon turnover repair, tendon turnover segment (without tenorrhaphy), direct repair or Pulvertaft weave. Tensile strength, stiffness and failure mechanisms were evaluated with a 500 N load cell. Turnover repair showed no significant difference in tensile strength to direct repair. Failure in turnover repair occurred largely at the site of tenorrhaphy due to suture pull-through or suture rupture. the increase in cross-sectional area after turnover repair was similar to that after direct repair, but less than after Pulvertaft weave. Tendon turnover offers tensile strength similar to direct repair with no associated increase in bulk. It provides a biomechanically secure and quicker alternative to tendon grafting for reconstructing tendon defects, without secondary donor site morbidity.Level of evidence: V.

Secondary donor-acceptor group enable efficient pure green organic light-emitting devices based on multi-resonance TADF emitters

Multi-resonance thermally activated delayed fluorescence (MR-TADF) presents great potential for applications in high-quality organic light emitting diodes (OLEDs) displays due to their superb properties of high color purity and high quantum efficiencies. Nonetheless, most reported MR-TADF emitters show unsatisfactory devices performances with severe efficiency roll-off resulted from their inherent issues of slow reverse intersystem crossing rate (kRISC) and aggregation-caused quenching (ACQ). Herein, we propose a novel strategy by employing quinazoline derivatives as secondary acceptor (PQ) and secondary donor–acceptor (PQCz) to provide intermediate locally excited triplet (3LE) states and then enhance spin-orbital coupling (SOC). In addition, the secondary donor–acceptor group PQCz in tCzBN-PQCz can suppress intermolecular interaction and provide dual long-range charge transfer (LRCT) channels to further enhance kRISC. Therefore, tCzBN-PQ and tCzBN-PQCz exhibit high kRISC of 5.6 × 105 s−1 and 7.3 × 105 s−1 with large photoluminescence quantum yield (PLQY) of 89 % and 95 % respectively. Consequently, OLED based on tCzBN-PQ and tCzBN-PQCz show excellent external quantum efficiency (EQE) of 30.2 % and 35.1 % with small efficiency roll-off and small full width at half maxima (FWHM) of 37 nm and 34 nm respectively. Especially, tCzBN-PQCz exhibits better performances and less-sensitive to the doping concentration which proves the effectiveness of this secondary donor–acceptor group.

Cr-Co Oxide Coatings Resistant to Corrosion, Electrodeposited on 304 SS Using an Ethylene Glycol-Water Solvent

The electrochemical co-deposition of Cr-Co oxide coatings at room temperature on 304 stainless steel (SS) was studied using an electrolyte composed of a mixture of ethylene glycol (EG), hydrated metal chloride salts (MCln∙YH2O), and water as a secondary hydrogen donor (HBD). Metallic Cu and Ni undercoats were applied to improve the adhesion of a posterior Cr-Co metallic and oxide layer. The electroactive events that took place during both electrodeposition processes were studied using cyclic voltammetry (CV) and chronoamperometry. The microstructure and composition of the surface layers were studied using scanning electron microscopy (SEM/EDS), X-ray diffraction (XRD) and cross-sectional elemental mapping via transmission electron microscopy (TEM). The surface of steel with the Cr-Co:EG-H2O coating showed greater resistance to pitting corrosion (123.93 mV) compared to untreated stainless steel (62.3 mV). This sample showed a large hystere-sis area, which is associated with high resistance to pitting corrosion by the occurrence of a re-passivation of the sample at a Erep value of 24.31 mV. After the cyclic potentiodynamic polariza-tion (CPP) test, the lowest specific mass loss (0.001 mg/cm2) was achieved for the AISI 304 SS sample coated using EG-water solvents (Cr-Co:EG-H2O), while the untreated AISI 304 SS reached a higher specific mass loss (0.01 mg/cm2). The Electrochemical Impedance Spectroscopy (EIS) tests showed that the uniform corrosion resistance varied significantly from the untreated AISI 304 SS (35 kΩ) to the coated sample (57 kΩ), which is attributed to the protection provided by the chromium and cobalt oxides coating. The best corrosion resistance achieved was correlated with a superhydrophobic character (with a contact angle of 158.41°) of the Cr-Co coatings. This was in turn a consequence of a needle-like morphology characteristic of these oxides.

Exploration of 4-substituted thiophene-based azo dyes for dye-sensitized solar cells and non-linear optical materials: synthesis and an in silico approach.

This work examines the effects of changing the secondary donors' donating strengths at the thiophene ring's fourth position in a range of dyes designated SR1 to SR9. The DFT results indicate that the molecular planarity is greatly affected by the placement of the secondary donor at position four, which changes the charge transfer (CT) characteristics in the thiophene-azo-salicylic acid backbone. These results are corroborated by TD-DFT analysis, which indicates that as the secondary donor's donating strength increases, so does the vertical absorption maximum. Based on the computed photovoltaic characteristics, these dyes perform better from SR1 to SR5. Research on dye@TiO2 clusters suggests a potential for binding with TiO2, which might cause the dye@TiO2 clusters' absorbance to shift red. Additionally, computed linear and non-linear optical (NLO) properties exhibit similar trends to those observed for DSSC performance. The experimental results, which include HOMO and LUMO energies as well as initial absorption in dimethylformamide (DMF), match very well with the patterns seen in DFT and TD-DFT calculations. The high thermal stability of SR1 to SR4 is indicated by thermogravimetric analysis (TGA), indicating their practical applicability in non-linear optics (NLO) and DSSC applications. The efficiencies of the produced DSSCs vary; SR4 has the highest efficiency (4.50 ± 0.1), and SR1 has the lowest (0.37 ± 0.1). The combined effects of theoretical and experimental DSSC results demonstrate the vital role of secondary donors in influencing molecular characteristics and NLO and DSSC performance.

Selective hydrogenation of vanillin over a graphene-encapsulated nitrogen-doped bimetallic magnetic Ni/Fe@NDC nano-catalyst.

One of the main obstacles to the development of sustainable biomass feedstocks today is the research of selective hydrogenation of biomass platform compounds for the synthesis of high-value chemicals. This work reports on the synthesis of a Ni/Fe bimetallic catalyst with nitrogen-doped carbon serving as the carrier, hydrogen serving as the primary donor, and isopropanol serving as the reaction medium and serving as a secondary donor. Vanillin was catalytically hydrogenated to produce 4-methylguaiacol, a complete hydrogenation product, under a reaction temperature of 200 °C for four hours. A single product with a good yield (95.26% conversion and selectivity up to 99%) was achieved by the moderate conditions, offering a potential route for the catalytic hydrogenation of biomass platform compounds.

An experimental investigation of the proton fraction in a three electrode 2.45 GHz ECR ion source

The ion beam extracted from a proton ion source contains H+ ion along with H2 + and H3 + molecular ions. In this work, the ionic fractions in the extracted beam of ECR ion source were measured using an analyzing magnet. A computerized proton fraction measurement setup is described in detail with instrumentation and control for pulsed operation of the ECR ion source. A timing diagram has been incorporated for trigger synchronization illustrating the process of pulsing the plasma, controlling the analyzing magnet parameters and acquiring data about the magnetic field and beam current. The proton fraction was measured in two cases, in the first case using SS304 plasma chamber and in the second case incorporating aluminium (Al) cylinder and boron nitride (BN) plates inside the plasma chamber. In the first case, the proton fraction was found to be in the range of ∼60% and in the second case because of the presence of secondary electron donors it increased to 93%. In order to understand the enhancement of H+ fraction in the hydrogen plasma, plasma parameters (ne , Te and EEDF) and its dependence on microwave power and neutral gas pressure were investigated.

Antibacterial properties of enzymatically treated PET fibers functionalized by nitric oxide

At present, microbes have enormous potential to become a major global public health issue. For example, Escherichia coli is the prominent cause of cholecystitis, urinary tract infections, and other infections. Due to its outstanding antibacterial properties, nitric oxide (NO) is essential for biological processes. Additionally, enzymatic hydrolysis using polyethylene terephthalate hydrolase (PETase) is one of the promising methods for PET upcycling. First, recombinant PETase was used to enzymatically treat waste PET fibers, and polyethylenimine (PEI) was added as a secondary amine donor. Subsequently, the aminated PET fiber was inserted into a reactor charged with NO gas (10 atm, 3 days) to obtain N-diazeniumdiolate (NONOate) products that can inhibit bacteria growth. In this study, the first strategy for antibacterial applications by NO-releasing PETase-hydrolyzed PET fibers was demonstrated. NO-conjugated PET fibers were successfully prepared which exhibits a continuous NO release profile over 12 h. The surface properties of functionalized PET fibers were successfully confirmed by fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and Griess assay. The antibacterial test indicated a reduction of Escherichia coli by 90.2% and Staphylococcus aureus by 71.1% after exposure to the functionalized material. Therefore, this novel antibacterial agent may offer great potential applications in the medical field.

Synthesis and catalytic properties of palladium(II) complexes with P,π-chelating ferrocene phosphinoallyl ligands and their non-tethered analogues.

Hybrid phosphines usually combine a phosphine moiety with another heteroatom secondary donor group in their structures while compounds equipped with hydrocarbyl π-donor moieties remain uncommon. This contribution reports the synthesis and structural characterization of the first P/π-allyl-chelating complexes that were obtained using the structurally flexible and redox-active ferrocene unit as the scaffold, viz. [PdCl(R2PfcCHCHCH2-η3:κP)] (1R; R = Ph and cyclohexyl (Cy); fc = ferrocene-1,1'-diyl). These compounds were synthesized from the respective phosphinoferrocene carboxaldehydes R2PfcCHO via reaction with vinylmagnesium bromide to generate 1-(phosphinoferrocenyl)allyl alcohols, which were subsequently acetylated. The resulting allyl acetates reacted smoothly with [Pd2(dba)3]/[Et3NH]Cl (dba = dibenzylideneacetone) to produce the target compounds. Complexes 1R and their nontethered analogues [PdCl(η3-C3H5)(FcPR2-κP)] (5R; Fc = ferrocenyl) were evaluated as pre-catalysts for the Pd-catalysed allylic amination of cinnamyl acetate with aliphatic amines and Suzuki-Miyaura-type cross-coupling of 4-tolylboronic acid with benzoyl chloride. In these reactions, better results were achieved with compounds 5R (particularly with 5Ph), presumably because they form more stable LPd(0)-type catalysts.

Nickel-decorated graphite phase carbon nitride photocatalysts coupled with carbazole-based calixarene dyes for high-efficiency visible light-driven hydrogen evolution

The development of artificial devices that mimic the highly efficient and sophisticated photosystems found in nature is a subject worthy of in-depth study. Two calixarene D-π-A dyes, C4-CZSTP and C4-CZBTP, containing an N-methylcarbazole group as a secondary auxiliary electron donor, are synthesized on the basis of our previously reported calixarene dye C4-BTP. These dyes are then cooperated with Ni-deposited g-C3N4 to prepare ternary photocatalysts, denoted as C4-CZSTP/Ni/g-C3N4, C4-CZBTP/Ni/g-C3N4 and C4-BTP/Ni/g-C3N4, and their photocatalytic performances are evaluated under visible light irradiation. The optimized 4.0 wt% C4-CZSTP/Ni/g-C3N4 sample gives a remarkable H2 evolution rate of 5552 μmol g−1 h−1, representing one of the highest records among the reported analogous systems based on g-C3N4. And after an extended test of 49 h, a total H2 yield of 63.57 mmol g−1 is obtained, corresponding to a turnover number (TON) based on C4-CZSTP moles (TONC4-CZSTP) of 3180. This performance can be attributed to the enhanced light-harvesting and photoelectron conversion of the as-prepared calixarene dyes, the adjusted energy levels and the effective cooperation of the three components. The optimal performance of C4-CZSTP/Ni/g-C3N4 among the three dye-sensitized systems is due to its higher lowest unoccupied molecular orbital (LUMO) value, i.e. stronger electronic driving force from the excited dye to g-C3N4. This study provides an interesting example for the design and preparation of a low-cost, high-efficiency and noble metal-free photocatalytic system for solar fuel production.

Optimising oral cancer reconstruction: a retrospective cohort study on the modified radial forearm free flap technique to eliminate the need for a secondary donor site

The radial forearm free flap (RFFF) is commonly used in the reconstruction of oral cancer patients. Traditional RFFF (TRFFF) techniques, which often require a secondary donor site to repair the forearm defect, may result in a scar extending to the dorsal hand. This can lead to significant functional and aesthetic concerns in the forearm. We designed a modified RFFF (MRFFF) that incorporates a glasses-shaped flap and features deep venous drainage. To evaluate its effectiveness we conducted a retrospective chart review of 105 patients with oral squamous cell carcinoma who underwent reconstructive surgery between 2018 and 2022. These patients were treated either with a TRFFF (n = 60) or the newly developed MRFFF (n = 45). Our inclusion criteria, guided by preliminary surgical experience prior to initiating the study, stipulated that single oral defects should be no larger than 6 × 6 cm2, and adjacent double defects no larger than 3 × 6 cm2. Flap size, pedicle length, harvesting duration, and anastomosis during the surgical procedure were compared between the two techniques. Preoperative and postoperative oral function, recurrence, mortality, and dorsal scarring were recorded. One-week, one-month, and six-month postoperative subjective aesthetics assessments, and self-reported postoperative donor hand function, were measured using the Michigan hand questionnaire (MHQ). There were no significant differences between the groups in terms of flap size, pedicle length, harvesting time, anastomosis time, postoperative oral function, recurrence, and mortality. However, patients with a MRFFF did not require a second donor graft site and did not have scars extending to the dorsal forearm. They also had significantly improved postoperative aesthetic outcomes (1 week: 70.6%, 1 month: 62.2%) and donor hand function (1 week: 54.6%, 1 month: 40.4%) compared with the TRFFF group (p < 0.001). The MRFFF eliminates the need for secondary donor sites and improves primary donor site outcomes. It is versatile and can be employed for either single or composite oral defects. Through extensive case studies, we have defined its specific scope: it is suitable for single defects measuring no more than 6 × 6 cm2, or for composite defects no larger than 3 × 6 cm2. Furthermore, it does not compromise the functional recovery of the recipient site, and should be widely adopted for all qualifying patients.

Harvesting electrons and holes from photodriven symmetry-breaking charge separation within a perylenediimide photosynthetic model dimer.

Understanding how to utilize symmetry-breaking charge separation (SB-CS) offers a path toward increasingly efficient light-harvesting technologies. This process plays a central role in the first step of photosynthesis, in which the dimeric "special pair" of the photosynthetic reaction center enters a coherent SB-CS state after photoexcitation. Previous research on SB-CS in both biological and synthetic chromophore dimers has focused on increasing the efficiency of light-driven processes. In a chromophore dimer undergoing SB-CS, the energy of the radical ion pair product is nearly isoenergetic with that of the lowest excited singlet (S1) state of the dimer. This means that very little energy is lost from the absorbed photon. In principle, the relatively high energy electron and hole generated by SB-CS within the chromophore dimer can each be transferred to adjacent charge acceptors to extend the lifetime of the electron-hole pair, which can increase the efficiency of solar energy conversion. To investigate this possibility, we have designed a bis-perylenediimide cyclophane (mPDI2) covalently linked to a secondary electron donor, peri-xanthenoxanthene (PXX) and a secondary electron acceptor, partially fluorinated naphthalenediimide (FNDI). Upon selective photoexcitation of mPDI2, transient absorption spectroscopy shows that mPDI2 undergoes SB-CS, followed by two secondary charge transfer reactions to generate a PXX•+-mPDI2-FNDI•- radical ion pair having a nearly 3 µs lifetime. This strategy has the potential to increase the efficiency of molecular systems for artificial photosynthesis and photovoltaics.

Automatic assessment of collaterals physiology in chronic total occlusions by means of artificial intelligence.

Assessment of collaterals physiology in chronic total occlusions (CTO) currently requires dedicated devices, adds complexity, and increases the cost of the intervention. This study sought to derive collaterals physiology from flow velocity changes (ΔV) in donor arteries, calculated with artificial intelligence- aided angiography. Angiographies with successful percutaneous coronary intervention (PCI) in 2 centers were retro- spectively analyzed. CTO collaterals were angiographically evaluated according to Rentrop and collateral connections (CC) classifications. Flow velocities in the primary and secondary collateral donor arteries (PCDA, SCDA) were automatically computed pre and post PCI, based on a novel deep-learning model to extract the length/time curve of the coronary filling in angiography. Parameters of collaterals physiology, Δcollateral-flow (Δfcoll) and Δcollateral-flow-index (ΔCFI), were derived from the ΔV pre-post. The analysis was feasible in 105 out of 130 patients. Flow velocity in the PCDA significantly decreased after CTO-PCI, proportionally to the angiographic collateral grading (Rentrop 1: 0.02 ± 0.01 m/s; Rentrop 2: 0.04 ± 0.01 m/s; Rentrop 3: 0.07 ± 0.02 m/s; p < 0.001; CC0: 0.01 ± 0.01 m/s; CC1: 0.04 ± ± 0.02 m/s; CC2: 0.06 ± 0.02 m/s; p < 0.001). Δfcoll and ΔCFI paralleled ΔV. SCDA also showed a greater reduction in flow velocity if its collateral channels were CC1 vs. CC0 (0.03 ± 0.01 vs. 0.01 ± 0.01 m/s; p < 0.001). For each individual patient, ΔV was more pronounced in the PCDA than in the SCDA. Automatic assessment of collaterals physiology in CTO is feasible, based on a deeplearning model analyzing the filling of the donor vessels in angiography. The changes in collateral flow with this novel method are quantitatively proportional to the angiographic grading of the collaterals.