Conformational Analysis of Conjugated Organic Materials: What Are My Heteroatoms Really Doing?

Organic semiconductor small molecules and polymers often incorporate heteroatoms into their chemical structures to affect the electronic properties of the material. A particular design philosophy has been to use these heteroatoms to influence torsional potentials, since the overlap of adjacent π-orbitals is most efficient in planar systems and is critical for charge delocalization in these systems. Since these design rules became popular, the messages from the earlier works have become lost in a sea of reports of "conformational locks", where the non-covalent interactions have relatively small contributions to planarizing torsional potentials. Greater influences can be found in the stabilization by extended conjugation, consideration of steric repulsion, and the interactions involving solubilizing chains and neighboring molecules or polymer chains in condensed phases.

Single-Component Electroactive Polymer Architectures for Non-Enzymatic Glucose Sensing.

Organic mixed ionic-electronic conductors (OMIECs) have emerged as promising materials for biological sensing, owing to their electrochemical activity, stability in an aqueous environment, and biocompatibility. Yet, OMIEC-based sensors rely predominantly on the use of composite matrices to enable stimuli-responsive functionality, which can exhibit issues with intercomponent interfacing. In this study, an approach is presented for non-enzymatic glucose detection by harnessing a newly synthesized functionalized monomer, EDOT-PBA. This monomer integrates electrically conducting and receptor moieties within a single organic component, obviating the need for complex composite preparation. By engineering the conditions for electrodeposition, two distinct polymer film architectures are developed: pristine PEDOT-PBA and molecularly imprinted PEDOT-PBA. Both architectures demonstrated proficient glucose binding and signal transduction capabilities. Notably, the molecularly imprinted polymer (MIP) architecture demonstrated faster stabilization upon glucose uptake while it also enabled a lower limit of detection, lower standard deviation, and a broader linear range in the sensor output signal compared to its non-imprinted counterpart. This material design not only provides a robust and efficient platform for glucose detection but also offers a blueprint for developing selective sensors for a diverse array of target molecules, by tuning the receptor units correspondingly.

Harnessing AI to unmask Copenhagen's invisible air pollutants: A study on three ultrafine particle metrics.

Ultrafine particles (UFPs) are airborne particles with a diameter of less than 100 nm. They are emitted from various sources, such as traffic, combustion, and industrial processes, and can have adverse effects on human health. Long-term mean ambient average particle size (APS) in the UFP range varies over space within cities, with locations near UFP sources having typically smaller APS. Spatial models for lung deposited surface area (LDSA) within urban areas are limited and currently there is no model for APS in any European city. We collected particle number concentration (PNC), LDSA, and APS data over one-year monitoring campaign from May 2021 to May 2022 across 27 locations and estimated annual mean in Copenhagen, Denmark, and obtained additionally annual mean PNC data from 6 state-owned continuous monitors. We developed 94 predictor variables, and machine learning models (random forest and bagged tree) were developed for PNC, LDSA, and APS. The annual mean PNC, LDSA, and APS were, respectively, 5523 pt/cm3, 12.0 µm2/cm3, and 46.1 nm. The final R2 values by random forest (RF) model were 0.93 for PNC, 0.88 for LDSA, and 0.85 for APS. The 10-fold, repeated 10-times cross-validation R2 values were 0.65, 0.67, and 0.60 for PNC, LDSA, and APS, respectively. The root mean square error for final RF models were 296 pt/cm3, 0.48 µm2/cm3, and 1.60 nm for PNC, LDSA, and APS, respectively. Traffic-related variables, such as length of major roads within buffers 100-150 m and distance to streets with various speed limits were amongst the highly-ranked predictors for our models. Overall, our ML models achieved high R2 values and low errors, providing insights into UFP exposure in a European city where average PNC is quite low. These hyperlocal predictions can be used to study health effects of UFPs in the Danish Capital.

Half of all hip and knee arthroplasty patients may be potential day-case candidates: a nationwide register study of 166,730 procedures.

BACKGROUND AND PURPOSE: The overall potential pool of day-case candidates on a national level in hip and knee arthroplasty is unknown. We aimed to estimate the proportion of hip and knee arthroplasty patients eligible for day-case surgery based on contemporary widely used criteria and determine whether there has been a change in the proportion of eligible patients over time and, secondarily, to investigate the proportion of eligible patients discharged on the day of surgery. METHODS: Based on data from the Danish National Patient Register, we identified all patients undergoing primary unilateral hip or knee arthroplasty from January 2010 to March 2020. Using a modification of day-case eligibility criteria proposed by a national multicenter collaboration, we sorted patients into either day-case eligible or ineligible. A day-case procedure was defined as discharge on the day of surgery. RESULTS: We included patients comprising a total of 166,730 primary total hip (THA), total knee (TKA), and unicompartmental knee arthroplasty (UKA). 48% (95% confidence interval [CI] 48-49) were eligible for day-case surgery, with a decline from 50% (CI 49-51) in 2010 to 46% (CI 46-47) eligible in 2019. More UKA patients were day-case eligible (55%, CI 54-56) than THA (47%, CI 47-48) and TKA patients (49%, CI 48-49). A maximum of 8.0% (CI 7.4-8.5) of eligible patients were discharged on the day of surgery in 2019. CONCLUSION: 48% of the Danish hip and knee arthroplasty patients were potential day-case candidates, with a small decline in eligibility from 50% in 2010 to 46% in 2019. Day of surgery discharge among day-case eligible patients peaked at 8% in 2019. Thus, the potential for more day-case surgery seems large.

Post-Transition-State Dynamic Effects in the Transmetalation of Pd(II)-F to Pd(II)-CF3.

The observation of post-transition-state dynamic effects in the context of metal-based transformation is rare. To date, there has been no reported case of a dynamic effect for the widely employed class of palladium-mediated coupling reactions. We performed an experimental and computational study of the trifluoromethylation of Pd(II)F, which is a key step in the Pd(0)/Pd(II)-catalyzed trifluoromethylation of aryl halides or acid fluorides. Our experiments show that the cis/trans speciation of the formed Pd(II)CF3 is highly solvent- and transmetalation reagent-dependent. We employed GFN2-xTB- and B3LYP-D3-based molecular dynamics trajectory calculations (with and without explicit solvation) along with high-level QM calculations and found that depending on the medium, different transmetalation mechanisms appear to be operative. A statistically representative number of Born-Oppenheimer molecular dynamics (MD) simulations suggest that in benzene, a difluorocarbene is generated in the transmetalation with R3SiCF3, which subsequently recombines with the Pd via two distinct pathways, leading to either the cis- or trans-Pd(II)CF3. Conversely, GFN2-xTB simulations in MeCN suggest that in polar/coordinating solvents an ion-pair mechanism is dominant. A CF3 anion is initially liberated and then rebinds with the Pd(II) cation to give a cis- or trans-Pd(II). In both scenarios, a single transmetalation transition state gives rise to both cis- and trans-species directly, owing to bifurcation after the transition state. The potential subsequent cis- to trans isomerization of the Pd(II)CF3 was also studied and found to be strongly inhibited by free phosphine, which in turn was experimentally identified to be liberated through displacement by a polar/coordinating solvent from the cis-Pd(II)CF3 complex. The simulations also revealed how the variation of the Pd-coordination sphere results in divergent product selectivities.

Poor usability of computer-assisted navigation for hip fracture surgery.

INTRODUCTION: The STRYKER ADAPT computer-assisted navigation system provides intraoperative feedback to the surgeon regarding implant placement of the Gamma3 nail. The usability of the ADAPT system has not been evaluated. The aim of the study was to investigate the perceived usability of the ADAPT system. MATERIALS AND METHODS: This was a descriptive study with prospectively collected data. ADAPT was introduced at Aarhus University Hospital in February 2021. Prior to introduction, surgeons at the department attended a general introduction to the system. ADAPT was introduced to the surgical nurses and was on display at the surgical ward at more than one occasion, where personal introduction to the system was possible. After introduction, it was mandatory to use ADAPT when using the Gamma3 nail to treat intertrochanteric femur fractures. After each procedure, primary and an eventual supervisor answered a questionnaire, which encompassed the System Usability Scale (SUS) questionnaire. The SUS is a ten-item questionnaire regarding the perceived usability of a system. SUS scores were translated to adjectives, describing user experience on a 7-point adjective scale (worst imaginable, awful, poor, ok, good, excellent, best imaginable). User acceptability, defined as "not acceptable", "marginal" or "acceptable", was also used to interpret the SUS scores. RESULTS: ADAPT was used in 50 procedures by 29 different surgeons, with varying skill-level. Median SUS-score after first-time use of ADAPT for all 29 surgeons was 43 (range: 5-60), which translated to "poor" or "not acceptable". For surgeons who performed ≥ 3 ADAPT-assisted procedures, there were no statistically significant difference in their first to latest SUS-score (median difference: 4.3, p = 0.5). In free text comments ADAPT was positively described as helpful in placement of K-wire and providing educational opportunities for inexperienced surgeons and negatively as inconsistent, slow, time consuming, and causing excessive fluoroscopy. CONCLUSIONS: Usability and acceptability of ADAPT was rated as "poor" or "not acceptable" by the majority of operating surgeons. ADAPT has not been used at our institution based on these findings. The System Usability Scale may be used in further research exploring usability and acceptability of novel computer-assisted navigation systems for orthopaedic surgery.

Computer-Assisted Intramedullary Nailing of Intertrochanteric Fractures Did Not Prevent Tip-Apex Distance Outliers.

Intertrochanteric femoral fractures are commonly treated with intramedullary nails (IMNs). A tip-apex distance (TAD) of more than 20-25 mm is associated with an increased risk of cut-out. The Stryker Adaptive Positioning System (ADAPT) is a computer-assisted navigation system designed to reduce TADs. We aim to assess if the ADAPT reduces the number of outliers with a TAD > 20 mm. All patients with intertrochanteric fractures treated with an IMN between 1 September 2020 and 12 March 2022 were included. Patients were included in three periods: a pre-ADAPT period (55 patients); an ADAPT period (50 patients), where it was compulsory to use the system; and a post-ADAPT period after the discontinuation of the system (59 patients). The TADs and lag screw protrusions beyond the lateral cortex were measured. The median TADs in the three periods were 17.0 mm (8-31 mm), 15.5 mm (9-30 mm), and 18.0 mm (11-32 mm), respectively. The absolute number of outliers with a TAD > 20 mm decreased from 15/55 patients in the pre-ADAPT period to 11/50 patients during the ADAPT period. This observation was not statistically significant, but this is likely due to the lack of power of the present study to show changes of this magnitude. However, our expectation that the ADAPT would diminish outliers markedly or close to zero outliers was not met, as we observed 11/50 = 22% outliers with a TAD > 20 mm when using computer-assisted surgery, i.e., ADAPT and Gamma3 for intertrochanteric fractures. Based on these findings, the use of the ADAPT was discontinued at our level 1 trauma center.

Interplay between Side Chain Density and Polymer Alignment: Two Competing Strategies for Enhancing the Thermoelectric Performance of P3HT Analogues.

A series of polythiophenes with varying side chain density was synthesized, and their electrical and thermoelectric properties were investigated. Aligned and non-aligned thin films of the polymers were characterized in the neutral and chemically doped states. Optical and diffraction measurements revealed an overall lower order in the thin films with lower side chain density, also confirmed using polarized optical experiments on aligned thin films. However, upon doping the non-aligned films, a sixfold increase in electrical conductivity was observed for the polythiophene with the lowest side chain density compared to poly(3-hexylthiophene) (P3HT). We found that the improvement in conductivity was not due to a larger charge carrier density but an increase in charge carrier mobility after doping with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ). On the other hand, doped aligned films did not show the same trend; lower side chain density instead led to a lower conductivity and Seebeck coefficient compared to those for P3HT. This was attributed to the poorer alignment of the polymer thin films with lower side chain density. The study demonstrates that optimizing side chain density is a synthetically simple and effective way to improve electrical conductivity in polythiophene films relevant to thermoelectric applications.

Peculiar transient behaviors of organic electrochemical transistors governed by ion injection directionality.

Despite the growing interest in dynamic behaviors at the frequency domain, there exist very few studies on molecular orientation-dependent transient responses of organic mixed ionic-electronic conductors. In this research, we investigated the effect of ion injection directionality on transient electrochemical transistor behaviors by developing a model mixed conductor system. Two polymers with similar electrical, ionic, and electrochemical characteristics but distinct backbone planarities and molecular orientations were successfully synthesized by varying the co-monomer unit (2,2'-bithiophene or phenylene) in conjunction with a novel 1,4-dithienylphenylene-based monomer. The comprehensive electrochemical analysis suggests that the molecular orientation affects the length of the ion-drift pathway, which is directly correlated with ion mobility, resulting in peculiar OECT transient responses. These results provide the general insight into molecular orientation-dependent ion movement characteristics as well as high-performance device design principles with fine-tuned transient responses.

The bleeding diathesis in patients with hereditary haemorrhagic telangiectasia is not due to impaired platelet function.

BACKGROUND: Patients with the rare disease; Hereditary haemorrhagic telangiectasia (HHT) often bleed from telangiectatic lesions in mucosal surfaces. Studies suggest that impaired platelet function may also play a role in their bleeding tendency. The aim of the present study was to investigate whether HHT-patients with epistaxis have impaired platelet function. METHOD: We conducted a case-control study based on a sample size calculation and included 22 HHT-patients (inclusion criteria: epistaxis severity score ≥ 4, no intake of medicine affecting platelet function the last 5 days, HHT-type 1 or 2, age ≥ 18 years) and 20 controls. We assessed the platelet function with standard haemostasis parameters, flow cytometry (platelet function and micro aggregation), rotational thromboelastometry and Platelet Function Analyzer 200. RESULTS: We found no significant difference in mean platelet volume and immature platelet fraction and no difference in platelet activation as measured by exposure of CD62P, CD63P and PAC1 binding. Nor did we find a significant difference in platelet aggregation response in HHT-patients compared with the control group for all agonists (thrombin receptor activating peptide, adenosine diphosphate and collagen-related peptide). The PFA-200 analysis was without difference between the two groups and thromboelastometry showed no impairment of global haemostasis. CONCLUSION: Reduced platelet function is unlikely to contribute to the frequent and long bleeding episodes that HHT-patients suffer from. We propose that further studies should focus on whether patients with HHT have hypercoagulability.

Quinoxaline derivatives as attractive electron-transporting materials.

This review article provides a comprehensive overview of recent advancements in electron transport materials derived from quinoxaline, along with their applications in various electronic devices. We focus on their utilization in organic solar cells (OSCs), dye-sensitized solar cells (DSSCs), organic field-effect transistors (OFETs), organic-light emitting diodes (OLEDs) and other organic electronic technologies. Notably, the potential of quinoxaline derivatives as non-fullerene acceptors in OSCs, auxiliary acceptors and bridging materials in DSSCs, and n-type semiconductors in transistor devices is discussed in detail. Additionally, their significance as thermally activated delayed fluorescence emitters and chromophores for OLEDs, sensors and electrochromic devices is explored. The review emphasizes the remarkable characteristics and versatility of quinoxaline derivatives in electron transport applications. Furthermore, ongoing research efforts aimed at enhancing their performance and addressing key challenges in various applications are presented.

No difference in short-term readmissions following day-case vs. one overnight stay in patients having hip and knee arthroplasty: a nationwide register study of 51,042 procedures from 2010-2020.

BACKGROUND AND PURPOSE: Day-case hip and knee arthroplasty has gained in popularity, but there are conflicting results regarding readmissions. We aimed to investigate differences in 30- and 90-day readmission rates between day-case patients and patients with a single overnight stay following primary total hip arthroplasty (THA), total knee arthroplasty (TKA), and unicompartmental knee arthroplasty (UKA). PATIENTS AND METHODS: We identified day-case (DC) and overnight (ON) THA, TKA, and UKA patients, operated on between 2010 and 2020, from the Danish National Patient Register. Day-case surgery was defined as discharge on the day of surgery. Overnight readmissions within 30 or 90 days of surgery were considered readmissions. We compared readmission rates between DC and ON patients within arthroplasty types using logistic regression adjusted for patient characteristics and year of surgery. We included 29,486 THAs (1,353 DC and 28,133 ON), 15,116 TKAs (617 DC and 14,499 ON), and 6,440 UKAs (1,528 DC and 4,914 ON). RESULTS: The 30-day readmission rates were: DC-THA 4.4% vs. ON-THA 4.4% (adjusted odds-ratio [aOR] 1.2, 95% confidence interval [CI] 0.91-1.6), DC-TKA 4.7% vs. ON-TKA 4.4% (aOR 1.1, CI 0.69-1.5), and DC-UKA 3.0% vs. ON-UKA 3.0% (aOR 1.1, CI 0.78-1.5). Similarly, no significant differences were present between DC and ON THA, TKA, and UKA regarding 90-day readmissions or time to readmission. CONCLUSION: We found no differences in readmission rates between day-case THA, TKA, and UKA patients and patients with a single overnight stay.

A Novel CDC42 Variant with Impaired Thymopoiesis, IL-7R Signaling, PAK1 Binding, and TCR Repertoire Diversity.

Genetic variants in cell division cycle 42 (CDC42) can manifest with dysmorphic features, autoinflammation, hemophagocytic lymphohistiocytosis, and thrombocytopenia, whereas defective thymopoiesis is a rare disease manifestation. We report a novel CDC42 missense variant (c.46A > G, p.Lys16Glu) resulting in infection and HPV-driven carcinogenesis in the mosaic mother and impaired thymopoiesis and profound T cell lymphopenia in the heterozygous daughter identified through newborn screening for SCID. We found that surface expression of IL-7Rα (CD127) was decreased, consistent with reduced IL-7-induced STAT5 phosphorylation and accelerated apoptotic T cell death. Consistent with the vital role of IL-7 in regulating thymopoiesis, both patients displayed reduced T cell receptor CDR3 repertoires. Moreover, the CDC42 variant prevented binding to the downstream effector, p21-activated kinase (PAK)1, suggesting this impaired interaction to underlie reduced IL-7Rα expression and signaling. Here, we provide the first report of severely compromised thymopoiesis and perturbed IL-7Rα signaling caused by a novel CDC42 variant and presenting with diverging clinical and immunological phenotypes in patients.

Sustainability considerations for organic electronic products.

The development of organic electronic applications has reached a critical point. While markets, including the Internet of Things, transparent solar and flexible displays, gain momentum, organic light-emitting diode displays lead the way, with a current market size of over $25 billion, helping to create the infrastructure and ecosystem for other applications to follow. It is imperative to design built-in sustainability into the materials selection, processing and device architectures of all of these emerging applications, and to close the loop for a circular approach. In this Perspective, we evaluate the status of embedded carbon in organic electronics, as well as options for more sustainable materials and manufacturing, including engineered recycling solutions that can be applied within the product architecture and at the end of life. This emerging industry has a responsibility to ensure a 'cradle-to-cradle' approach. We highlight that ease of dismantling and recycling needs to closely relate to the product lifetime, and that regeneration should be facilitated in product design. Materials choices should consider the environmental effects of synthesis, processing and end-product recycling as well as performance.

Low protection from breakthrough SARS-CoV-2 infection and mild disease course in ocrelizumab-treated patients with multiple sclerosis after three mRNA vaccine doses.

BACKGROUND: Our study investigated the rate of breakthrough SARS-CoV-2 infection and clinical outcomes in a cohort of multiple sclerosis (MS) patients who were treated with the anti-CD20 monoclonal antibody (Ab), ocrelizumab, before first, second and third BNT162b2 mRNA vaccinations. To correlate clinical outcomes with the humoral and cellular response. METHODS: The study was a prospective non-randomised controlled multicentre trial observational study. Participants with a diagnosis of MS who were treated for at least 12 months with ocrelizumab prior to the first BNT162b2 mRNA vaccination were prospectively followed up from January 2021 to June 2022. RESULTS: Out of 54 participants, 32 (59.3%) developed a positive SARS-CoV-2 PCR test in the study period. Mild infection was observed in all infected participants. After the third vaccination, the non-infected participants had higher mean Ab levels compared to the infected participants (54.3 binding antibody unit (BAU)/mL vs 26.5 BAU/mL, p=0.030). The difference in reactivity between spike-specific CD4+ and CD8+ T lymphocytes in the two groups was not significant. CONCLUSION AND RELEVANCE: The study results demonstrate rates of 59% in breakthrough infections after the third SARS-CoV-2 mRNA vaccination in ocrelizumab-treated patients with MS, without resulting in critical disease courses. These findings suggest the need for continuous development of prophylactic treatments when proved important in the protection of severe breakthrough infection.

The Influence of Regiochemistry on the Performance of Organic Mixed Ionic and Electronic Conductors.

Thiophenes functionalised in the 3-position are ubiquitous building blocks for the design and synthesis of organic semiconductors. Their non-centrosymmetric nature has long been used as a powerful synthetic design tool exemplified by the vastly different properties of regiorandom and regioregular poly(3-hexylthiophene) owing to the repulsive head-to-head interactions between neighbouring side chains in the regiorandom polymer. The renewed interest in highly electron-rich 3-alkoxythiophene based polymers for bioelectronic applications opens up new considerations around the regiochemistry of these systems as both the head-to-tail and head-to-head couplings adopt near-planar conformations due to attractive intramolecular S-O interactions. To understand how this increased flexibility in the molecular design can be used advantageously, we explore in detail the geometrical and electronic effects that influence the optical, electrochemical, structural, and electrical properties of a series of six polythiophene derivatives with varying regiochemistry and comonomer composition. We show how the interplay between conformational disorder, backbone coplanarity and polaron distribution affects the mixed ionic-electronic conduction. Ultimately, we use these findings to identify a new conformationally restricted polythiophene derivative for p-type accumulation-mode organic electrochemical transistor applications with performance on par with state-of-the-art mixed conductors evidenced by a µC* product of 267 F V-1 cm-1 s-1 .

10-year evolution of day-case hip and knee arthroplasty: a Danish nationwide register study of 166,833 procedures from 2010 to 2020.

BACKGROUND AND PURPOSE: No previous studies have investigated the use of day-case arthroplasty in Denmark on a national scale. We investigated the frequency of day-case surgery in total hip (THA), total knee (TKA), and unicompartmental knee arthroplasty (UKA) from 2010 to 2020 in Denmark. PATIENTS AND METHODS: Primary unilateral THAs, TKAs, and UKAs performed for osteoarthritis were identified in the Danish National Patient Register using procedural and diagnosis codes. Day-case surgery was defined as discharge on the day of surgery. 90-day readmissions were defined as any overnight admissions following discharge. RESULTS: From 2010 to 2020 Danish surgical centers performed 86,070 THAs, 70,323 TKAs, and 10,440 UKAs. From 2010 to 2014, less than 0.5% of THAs and TKAs were day-case procedures. They increased to 5.4% (95% confidence interval [CI] 4.9-5.8) of THAs and 2.8% (CI 2.4-3.2) of TKAs in 2019. From 2010 to 2014, 11% of UKAs were day-case procedures, but they increased to 20% (CI 18-22) in 2019. This increase was driven by a few surgical centers (3-7 centers). In 2010, readmission rates within 90 days of surgery were 10% after THAs and 11% after TKAs, and 9.4% for both THAs and TKAs in 2019. Readmission rates after UKA fluctuated between 4% and 7%. CONCLUSION: From 2010 to 2020 the use of day-case surgery in THA, TKA, and UKA increased in Denmark, driven by only a few centers. During the same period readmissions did not increase.

Aqueous processing of organic semiconductors enabled by stable nanoparticles with built-in surfactants.

The introduction of oligoether side chains onto a polymer backbone can help to stabilise polymeric dispersions in water without the necessity of surfactants or additives when conjugated polymer nanoparticles are prepared. A series of poly(3-hexylthiophene) (P3HT) derivatives with different content of a polar thiophene derivative 3-((2-methoxyethoxy)methyl)thiophene was interrogated to find the effect of the polar chains on the stability of the formed nanoparticles, as well as their structural, optical, electrochemical, and electrical properties. Findings indicated that incorporation of 10-20 percent of the polar side chain led to particles that are stable over a period of 42 days, with constant particle size and polydispersity, however the particles from the polymer with 30 percent polar side chain showed aggregation effects. The polymer dispersions showed a stronger solid-like behaviour in water with decreasing polar side chain content, while thin film deposition from water was found to afford globular morphologies and crystallites with more isotropic orientation compared to conventional solution-processed films. As a proof-of-principle, field-effect transistors were fabricated directly from the aqueous dispersions demonstrating that polymers with hydrophilic moieties can be processed in water without the requirement of surfactants.

Highly Efficient Mixed Conduction in a Fused Oligomer n-Type Organic Semiconductor Enabled by 3D Transport Pathways.

Tailoring organic semiconductors to facilitate mixed conduction of ionic and electronic charges when interfaced with an aqueous media has spurred many recent advances in organic bioelectronics. The field is still restricted, however, by very few n-type (electron-transporting) organic semiconductors with adequate performance metrics. Here, a new electron-deficient, fused polycyclic aromatic system, TNR, is reported with excellent n-type mixed conduction properties including a µC* figure-of-merit value exceeding 30 F cm-1 V-1 s-1 for the best performing derivative. Comprising three naphthalene bis-isatin moieties, this new molecular design builds on successful small-molecule mixed conductors; by extending the molecular scaffold into the oligomer domain, good film-forming properties, strong π-π interactions, and consequently excellent charge-transport properties are obtained. Through judicious optimization of the side chains, the linear oligoether and branched alkyl chain derivative bgTNR is obtained which shows superior mixed conduction in an organic electrochemical transistor configuration including an electron mobility around 0.3 cm2 V-1 s-1 . By optimizing the side chains, the dominant molecular packing can be changed from a preferential edge-on orientation (with high charge-transport anisotropy) to an oblique orientation that can support 3D transport pathways which in turn ensure highly efficient mixed conduction properties across the bulk semiconductor film.

Precision Measurement of Trident Production in Strong Electromagnetic Fields.

We demonstrate experimentally that the trident process e^{-}→e^{-}e^{+}e^{-} in a strong external field, with a spatial extension comparable to the effective radiation length, is well understood theoretically. The experiment, conducted at CERN, probes values for the strong field parameter χ up to 2.4. Experimental data and theoretical expectations using the local constant field approximation show remarkable agreement over almost 3 orders of magnitude in yield.