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© 2014 American Chemical Society. Photocurrent spectroscopy is used to measure both the charge transfer and exciton optical absorption spectra of various bulk heterojunction organic solar cells. The energy difference between the polymer HOMO energy and the fullerene LUMO energy is obtained from the spectra, along with the disorder energy. Combining information from cells with several different polymers and fullerenes allows measurements of the energy differences between HOMO or LUMO energies for about 10 different polymers and fullerenes, with an estimated uncertainty of 50 meV. Heterojunction band offsets are obtained for the various cells, distinguishing between the excitonic and the single-carrier band offsets. The cell open-circuit voltage is shown to be closely correlated with the interface band gap. The exciton disorder energy is directly correlated to the band-tail disorder and we also consider the effects of exciton thermalization on the charge generation mechanism. The data indicate that an energy offset between the polymer exciton and the charge transfer ground state below about 0.25 eV adversely affects the cell performance, while a HOMO band offset below about 0.2-0.3 eV also degrades cell performance but by a different mechanism.

Introduction: Empathy is a fundamental element of high-quality healthcare, though it has been shown to be in decline among medical students and residents. Appeals have therefore been made for the development of evidence-based empathy-enhancing experiential learning and training models. Bringing Art to Life (BATL) is a service-learning program designed within experiential learning pedagogy for psychology and pre-healthcare students. Intergenerational relationships are fostered with people with dementia through art therapy and life story/narrative at a community-based adult day services center., Methods: In this sequential mixed methods study, quantitative data were collected via electronic surveys of students in this course compared with students in didactic introductory psychology or psychology and aging courses. Survey measures included empathy, mindfulness, positive and negative affect, future time perspective, and attitudes toward older adults and working with people with dementia. Weekly BATL student journals submitted as part of their course requirements were analyzed using qualitative content analysis., Results: Within-subjects analyses of variance revealed increases in empathy and positive affect, broadened time perspective, and improved attitudes toward older adults and people with dementia among students in the BATL course compared with other undergraduate students. Analysis of BATL student journals supported and deepened understanding of these findings, with themes including attitude change, relationship building fostering existential awareness and self-development, art fostering social interactions, and perceived program effectiveness., Discussion: The findings suggest that BATL strongly supports increased empathetic attitudes and decreased stigma of aging in psychology and pre-healthcare students. Intergenerational expressive arts-based programs like BATL should be implemented in healthcare education to enhance empathy and improve attitudes toward aging and dementia care., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Peeples, Thompson, Tucker, Smith, Brown, Carden, Halli-Tierney, Duncan, Aggarwal, Allen, Allen and Potts.)

Acetyl coenzyme A synthase (ACS) catalyzes the formation and deconstruction of the key biological metabolite, acetyl coenzyme A (acetyl-CoA). The active site of ACS features a {NiNi} cluster bridged to a [Fe 4 S 4 ] n + cubane known as the A-cluster. The mechanism by which the A-cluster functions is debated, with few model complexes able to replicate the oxidation states, coordination features, or reactivity proposed in the catalytic cycle. In this work, we isolate the first bimetallic models of two hypothesized intermediates on the paramagnetic pathway of the ACS function. The heteroligated {Ni 2+ Ni 1+ } cluster, [K(12-crown-4) 2 ][ 1 ], effectively replicates the coordination number and oxidation state of the proposed "A red " state of the A-cluster. Addition of carbon monoxide to [ 1 ] - allows for isolation of a dinuclear {Ni 2+ Ni 1+ (CO)} complex, [K(12-crown-2) n ][ 2 ] ( n = 1-2), which bears similarity to the "A NiFeC " enzyme intermediate. Structural and electronic properties of each cluster are elucidated by X-ray diffraction, nuclear magnetic resonance, cyclic voltammetry, and UV/vis and electron paramagnetic resonance spectroscopies, which are supplemented by density functional theory (DFT) calculations. Calculations indicate that the pseudo-T-shaped geometry of the three-coordinate nickel in [ 1 ] - is more stable than the Y-conformation by 22 kcal mol -1 , and that binding of CO to Ni 1+ is barrierless and exergonic by 6 kcal mol -1 . UV/vis absorption spectroscopy on [ 2 ] - in conjunction with time-dependent DFT calculations indicates that the square-planar nickel site is involved in electron transfer to the CO π*-orbital. Further, we demonstrate that [ 2 ] - promotes thioester synthesis in a reaction analogous to the production of acetyl coenzyme A by ACS.

Controlling reactivity with electric fields is a persistent challenge in chemistry. One approach is to tether ions at well-defined locations near a reactive center. To quantify fields arising from ions, we report crown ethers that capture metal cations as field sources and a covalently bound vibrational Stark shift probe as a field sensor. We use experiments and computations in both the gas and liquid phases to quantify the vibrational frequencies of the probe and estimate the electric fields from the captured ions. Cations, in general, blue shift the probe frequency, with effective fields estimated to vary in the range of ∼0.2-3 V/nm in the liquid phase. Comparison of the gas and liquid phase data provides insight into the effects of mutual polarization of the molecule and solvent and screening of the ion's field. These findings reveal the roles of charge, local screening, and geometry in the design of tailored electric fields.

Complexes featuring multiple metal centres are of growing interest regarding metal-metal cooperation and its tuneability. Here the synthesis and characterisation of heterobimetallic complexes of a 3d metal (4: Mn, 5: Co) and lanthanum supported by a (1,1,1-tris[(3-methoxysalicylideneamino)methyl]ethane) ligand is reported, as well as discussion of their electronic structure via electron paramagnetic resonance (EPR) spectroscopy, electrochemical experiments and computational studies. Competitive binding experiments of the ligand and various metal salts unequivocally demonstrate that in these heterobimetallic complexes the 3d metal (Mn, Co) selectively occupies the κ 6 -N 3 O 3 binding site of the ligand, whilst La occupies the κ 6 -O 6 metal binding site in line with their relative oxophilicities. EPR spectroscopy supported by density functional theory analysis indicates that the 3d metal is high spin in both cases ( S = 5/2 (Mn), 3/2 (Co)). Cyclic voltammetry studies on the Mn/La and Co/La bimetallic complexes revealed a quasi-reversible Mn 2+/3+ redox process and poorly-defined irreversible oxidation events respectively.

This study explores the influence of electronic and ionic conductivities on the behavior of conjugated polymer binders through the measurement of entropic potential and heat generation in an operating lithium-ion battery. Specifically, the traditional poly(vinylidene fluoride) (PVDF) binder in LiNi 0.8 Co 0.15 Al 0.05 O 2 (NCA) cathode electrodes was replaced with semiconducting polymer binders based on poly(3,4-propylenedioxythiophene). Two conjugated polymers were explored: one is a homopolymer with all aliphatic side chains, and the other is a copolymer with both aliphatic and ethylene oxide side chains. We have shown previously that both polymers have high electronic conductivity in the potential range of NCA redox, but the copolymer has a higher ionic conductivity and a slightly lower electronic conductivity. Entropic potential measurements during battery cycling revealed consistent trends during delithiation for all of the binders, indicating that the binders did not modify the expected NCA solid solution deintercalation process. The entropic signature of polymer doping to form the conductive state could be clearly observed at potentials below NCA oxidation, however. Operando isothermal calorimetric measurements showed that the conductive binders resulted in less Joule heating compared to PVDF and that the net electrical energy was entirely dissipated as heat. In a comparison of the two conjugated polymer binders, the heat dissipation was lower for the homopolymer binder at lower C-rates, suggesting that electronic conductivity rather than ionic conductivity was the most important for reducing Joule heating at lower rates, but that ionic conductivity became more important at higher rates., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Molecular design is crucial for endowing conjugated polymers (CPs) with unique properties and enhanced electronic performance. Introducing Hydrogen-bonding (H-bonding) into CPs has been a broadly exploited, yet still emerging strategy capable of tuning a range of properties encompassing solubility, crystallinity, electronic properties, solid-state morphology, and stability, as well as mechanical properties and self-healing properties. Different H-bonding groups can be utilized to tailor CPs properties based on the applications of interest. This review provides an overview of classes of H-bonding CPs (assorted by the different H-bond functional groups), the synthetic methods to introduce the corresponding H-bond functional groups and the impact of H-bonding in CPs on corresponding electronic and materials properties. Recent advances in addressing the trade-off between electronic performance and mechanical durability are also highlighted. Furthermore, insights into future directions and prospects for H-bonded CPs are discussed., (© 2023 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Non-conjugated pendant electroactive polymers (NCPEPs) are an emerging class of polymers that offer the potential of combining the desirable optoelectronic properties of conjugated polymers with the superior synthetic methodologies and stability of traditional non-conjugated polymers. Despite an increasing number of studies focused on NCPEPs, particularly on understanding fundamental structure-property relationships, no attempts have been made to provide an overview on established relationships to date. This review showcases selected reports on NCPEP homopolymers and copolymers that demonstrate how optical, electronic, and physical properties of the polymers are affected by tuning of key structural variables such as the chemical structure of the polymer backbone, molecular weight, tacticity, spacer length, the nature of the pendant group, and in the case of copolymers the ratios between different comonomers and between individual polymer blocks. Correlation of structural features with improved π-stacking and enhanced charge carrier mobility serve as the primary figures of merit in evaluating impact on NCPEP properties. While this review is not intended to serve as a comprehensive summary of all reports on tuning of structural parameters in NCPEPs, it highlights relevant established structure-property relationships that can serve as a guideline for more targeted design of novel NCPEPs in the future., (© 2023 The Authors. Macromolecular Rapid Communications published by Wiley-VCH GmbH.)

While a major improvement to the sustainability of conjugated polymer synthesis, traditional direct arylation polymerization (DArP) still requires high temperatures (typically >100 °C), necessitating a significant energy input requirement. Performing DArP at reduced or ambient temperatures would represent an improvement to the sustainability of the reaction. Here we describe the first report of a well-defined conjugated polymer synthesized by DArP at room temperature. Previous efforts toward room temperature DArP relied on the use of a near-stoichiometric silver reagent, an expensive coinage metal, which makes the reaction less cost-effective and sustainable. Here, room temperature polymerizations of 3,4-ethylenedioxythiophene (EDOT) and 9,9-dioctyl-2,7-diiodofluorene were optimized and provided molar mass ( M n ) up to 11 kg/mol PEDOTF, and performing the reaction at the standard ambient temperature of 25 °C provided M n up to 15 kg/mol. Model studies using other C-H monomers of varying electron density copolymerized with 9,9-dioctyl-2,7-diiodofluorene provided insight into the scope of the room temperature polymerization, suggesting that performing room temperature DArP is highly dependent on the electron richness of the C-H monomer.

Designing new polymer semiconductors for intrinsically stretchable polymer solar cells (IS-PSCs) with high power conversion efficiency (PCE) and durability is critical for wearable electronics applications. Nearly all high-performance PSCs are constructed using fully conjugated polymer donors ( P D ) and small-molecule acceptors (SMA). However, a successful molecular design of P D s for high-performance and mechanically durable IS-PSCs without sacrificing conjugation has not been realized. In this study, we design a novel thymine side chain terminated 6,7-difluoro-quinoxaline (Q-Thy) monomer and synthesize a series of fully conjugated P D s (PM7-Thy5, PM7-Thy10, PM7-Thy20) featuring Q-Thy. The Q-Thy units capable of inducing dimerizable hydrogen bonding enable strong intermolecular P D assembly and highly efficient and mechanically robust PSCs. The PM7-Thy10:SMA blend demonstrates a combination of high PCE (>17%) in rigid devices and excellent stretchability (crack-onset value >13.5%). More importantly, PM7-Thy10-based IS-PSCs show an unprecedented combination of PCE (13.7%) and ultrahigh mechanical durability (maintaining 80% of initial PCE after 43% strain), illustrating the promising potential for commercialization in wearable applications.

While polymers containing chain or ring motifs in their backbone are ubiquitous, those containing well-defined molecular cages are very rare and essentially unknown for the inorganic elements. We report that a rigid and dinucleophilic cage (PNSiMe 3 ) 2 (NMe) 6 , which is chemically robust and accessible on a multi-gram scale from commercial precursors, serves as a linear and divalent connector that forms cage-dense inorganic materials. Reaction of the cage with various ditopic P(III) dihalide comonomers proceeded via Me 3 SiCl elimination to give high molecular weight (30 000-70 000 g mol -1 ), solution-processable polymers that form free-standing films. The end groups of the polymers could be tuned to engender orthogonal reactivity and form block copolymers. Networked cage-dense materials could be accessed by using PCl 3 as a tritopic P(III) linker. Detailed mechanistic studies implicate a stepwise polycondensation that proceeds via phosphino-phosphonium ion intermediates, prior to Me 3 SiCl loss. Thus, metathesis between the dinucleophilic cage and polyhalides represents a general strategy to making cage-dense polymers, setting the stage for systematically understanding the consequences of the three-dimensional microstructure on macroscopic material properties.

Vibrational Stark probes are incisive tools for measuring local electric fields in a wide range of chemical environments. The interpretation of the frequency shift often gets complicated due to the specific interactions of the probe, such as hydrogen bonding and Lewis bonding. Therefore, it is important to distinguish between the pure electrostatic response and the response due to such specific interactions. Here we report a molecular system that is sensitive to both the Stark effect from a single ion and the explicit Lewis bonding of ions with the probe. The molecule consists of a crown ether with an appended benzonitrile. The crown captures cations of various charges, and the electric field from the ions is sensed by the benzonitrile probe. Additionally, the lone pair of the benzonitrile can engage in Lewis interactions with some of the ions by donating partial charge density to the ions. Our system exhibits both of these effects and therefore is a suitable test bed for distinguishing between the pure electrostatic and the Lewis interactions. Our computational results show that the electrostatic influence of the ion is operative at large distances, while the Lewis interaction becomes important only within distances that permit orbital overlap. Our results may be useful for using the nitrile probe for measuring electrostatic and coordination effects in complex ionic environments such as the electrode-electrolyte interfaces.

The stereoregular nonconjugated pendant electroactive polymer (NCPEP) poly(( N -carbazolylethylthio) propyl methacrylate) (PCzETPMA) has recently shown charge carrier mobilities that are on par with conjugated polymers. Here, we increased the complexity of the architecture for this NCPEP by introducing a polystyrene (PS) block via an anionic, living polymerization yielding a family of PS- b -PCzETPMA block copolymers as the first examples of NCPEP- block -copolymers with controlled stereoregularity of the NCPEP-blocks. Through this methodology we were able to control the molar masses, PS to PCzETPMA block ratios, and tacticities of the PCzETPMA-blocks. We found all three parameters to significantly impact the hole mobilities (μ h ) of the resulting copolymers, which increased with higher molar masses, longer PCzETPMA-blocks, and higher isotacticity of the PCzETPMA-block, giving the best μ h of 2.33 × 10 -5 cm 2 /V·s after annealing at 150 °C for the highest molar mass copolymer with a dominant isotactic PCzETPMA-block. This work is the first reported synthesis of a block copolymer bearing a NCPEP-block with a controlled tacticity and demonstrates that such complex polymer architectures can be realized with NCPEPs while maintaining control over their stereoregularity and without significantly suppressing the hole mobility in the resulting copolymers.

The optical and electrochemical properties of quadruply bonded dimolybdenum paddlewheel complexes (Mo 2 PWCs) make them ideal candidates for incorporation into functional materials or devices, but one of the greatest bottlenecks for this is their poor stability toward atmospheric oxygen. By tuning the potential at which the Mo 2 core is oxidized, it was possible to increase the tolerance of Mo 2 PWCs to air. A series of homoleptic Mo 2 PWCs bearing fluorinated formamidinate ligands have been synthesized and their electrochemical properties studied. The oxidation potential of the complexes was tuned in a predictable fashion by controlling the positions of the fluorine substituents on the ligands, as guided by a Hammett relationship. Studies into the air stability of the resulting complexes by multinuclear NMR spectroscopy show an increased tolerance to atmospheric oxygen with increasingly electron-withdrawing ligands. The heteroleptic complex Mo 2 (D F ArF) 3 (OAc) [where D F ArF = 3,5-(difluorophenyl)formamidinate] shows remarkable tolerance to oxygen in the solid state and in chloroform solutions. Through the employment of easily accessible ligands, the stability of the Mo 2 core toward oxygen has been enhanced, thereby making Mo 2 PWCs with electron-withdrawing ligands more attractive candidates for the development of functional materials.

Despite the inherent sustainability direct arylation polymerization (DArP) offers through a C-H activation pathway, the use of expensive homogeneous Pd catalysts remains problematic for large-scale conjugated polymer (CP) synthesis. Herein, the first report on the recycling of heterogeneous catalysts for CP synthesis using DArP is presented. We found Silia Cat Pd-DPP to be a highly efficient and recyclable catalyst for multi-batch CP synthesis providing CPs with molecular weights ( M n ) up to 82 kg/mol even after being recycled three times. Batch-to-batch variations were further optimized to afford up to five batches of polymers with a M n of 25 ± 2.5 kg/mol without structural disparity. Significantly, this work discloses among the most sustainable CP synthesis protocols to date and presents the critical concept of catalyst-recycling to the important field of organic semiconducting polymers, which potentially enables access to truly low-cost flow chemistry for industrial-scale CP synthesis.

Isotactic nonconjugated pendant electroactive polymers (NCPEPs) have recently shown potential to achieve comparable charge carrier mobilities with conjugated polymers. Here we report the broader influence of tacticity in NCPEPs, using poly(( N -carbazolylethylthio)propyl methacrylate) (PCzETPMA) as a model polymer. We utilized the thiol-ene reaction as an efficient postpolymerization functionalization method to achieve pendant polymers with high isotacticity and syndiotacticity. We found that a stereoregular isotactic polymer showed ∼100 times increased hole mobility (μ h ) as compared to both atactic and low molecular weight syndiotactic PCzETPMA, achieving μ h of 2.19 × 10 -4 cm 2 V -1 s -1 after annealing at 120 °C. High molecular weight syndiotactic PCzETPMA gave ∼10 times higher μ h than its atactic counterpart, comparable to isotactic PCzETPMA after annealing at 150 °C. Importantly, high molecular weight syndiotactic PCzETPMA showed a dramatic increase in μ h to 1.82 × 10 -3 cm 2 V -1 s -1 when measured after annealing at 210 °C, which surpassed the well-known conjugated polymer poly(3-hexylthiophene) (P3HT) (μ h = 4.51 × 10 -4 cm 2 V -1 s -1 ). MD simulations indicated short-range π-π stacked ordering in the case of stereoregular isotactic and syndiotactic polymers. This work is the first report of charge carrier mobilities in syndiotactic NCPEPs and demonstrates that the tacticity, annealing conditions, and molecular weight of NCPEPs can strongly affect μ h .

For over a decade, Direct Arylation Polymerization (DArP) has been demonstrated to be an eco-friendly, facile, and low-cost alternative to conventional methodologies such as Stille polymerization for conjugated polymer synthesis. By accessing through a C-H activation pathway, DArP offers a reduction of synthetic steps while eliminating the generation of stoichiometric, highly toxic organotin byproducts. However, as the major component in these reactions, the solvents most prevalently employed for DArP are hazardous and produced from unsustainable sources, such as dimethylacetamide (DMA), tetrahydrofuran (THF), and toluene. Although the use of sustainable alternative solvents such as 2-MeTHF and cyclopentyl methyl ether (CPME) has recently emerged, drawbacks of ethereal solvents include the need for a pressurized reaction setup as well as potential peroxide formation. While aromatic solvents are superior in solubilizing conjugated polymers, very little has been done in searching for more sustainable, benign alternatives for this class of solvent. Herein, we report the application of a sustainable, naturally sourced, high-boiling aromatic solvent, p-cymene, to DArP for the first time. p-Cymene was found to display excellent solubilizing ability in the synthesis of a broad scope of alternating copolymers with M n up to 51.3 kg/mol and yields up to 96.2%, outperforming those prepared using CPME and toluene. Structural analysis revealed the exclusion of defects in these polymers prepared using p-cymene as the solvent which, in the case of a 2,2'-bithiophene monomer, is challenging to access through the use of conventional solvents for DArP, such as DMA and toluene.

In the search for semiconducting polymer alternatives to conjugated polymers, stereoregular nonconjugated pendant electroactive polymers (NCPEPs) have recently shown competitive hole mobilities with conjugated polymers and a dramatic increase in mobility relative to atactic analogues. Here we investigate one of the key structural variables of NCPEPs: the flexible alkyl spacer that separates the electroactive pendant from the backbone. We investigate a straightforward postpolymerization functionalization synthetic method to synthesize such polymers with high isotacticity using poly( N- carbazolylalkyl acrylate) as a model system, where the alkyl chain spacer in the NCPEPs is varied from 2 to 12 carbons. We observed that the hole mobility increased from the two-carbon spacer, resulting in the highest mobility upon thermal annealing with a four-carbon spacer for 75% isotactic polymers and with a six-carbon spacer for 87% isotactic polymers. As such, we have demonstrated an important role of the spacer chain in influencing mobility. For all spacer lengths, higher mobilities were measured with the more isotactic polymer. While physical characterization of the largely amorphous polymers yielded little insight into the structure-function relationships, DFT and MD simulations indicated helical structures for the polymers where intermolecular short-range π-stacking is observed and is affected by spacer chain length. This work demonstrates that both the degree of stereoregularity and the spacer chain length play a role in determining the hole mobility in NCPEPs.

Objective: To assess changes in presentations to EDs during the COVID-19 pandemic lockdown in the Southern Region of New Zealand., Methods: We conducted a retrospective audit of patients attending EDs in the Southern District Health Board (SDHB), from 1 March to 13 May 2020. We made comparisons with attendances during the same period in 2019. The 2020 study period included 'pre-lockdown' (1 March-25 March), 'level 4 (strict) lockdown' (26 March-27 April) and 'level 3 (eased) lockdown' (28 April-13 May)., Results: Patient volumes reduced in all SDHB EDs during levels 4 and 3, mostly representing a loss of low acuity patients (Australasian Triage Scale 3, 4 and 5), although high-acuity presentations also declined. Average patient age increased by 5 years; however, the proportions of sexes and ethnicities did not change. Presentations of cerebrovascular accidents and appendicitis did not change significantly. Trauma, mental health, acute coronary syndrome and infectious respiratory presentations decreased significantly during level 4, and infectious respiratory presentations decreased further in level 3., Conclusions: Within the SDHB, patient volumes reduced during levels 4 and 3 of our lockdown, with reduced low-acuity presentations. High-acuity patient numbers also declined. Trauma, mental health, alcohol-related, infectious respiratory and acute coronary syndrome presentations declined while cerebrovascular accident and appendicitis numbers showed little to no change., (© 2021 Australasian College for Emergency Medicine.)

Transarterial radioembolization (TARE) effectively treats unresectable primary and metastatic liver tumors through intra-arterial injection of Yttrium-90 ( 90 Y) beta particle emitting microspheres which implant around the tumor. Current dosimetry models are highly simplistic and there is a large need for an image-based dosimetry post-TARE, which would improve treatment safety and efficacy. Current post-TARE imaging is 90 Y bremsstrahlung SPECT/CT and we study the use of these images for dosimetry. Retrospective image review of ten patients having a Philips Healthcare TM SPECT/CT following TARE SIR-Spheres® implantation. Emission series with attenuation correction were resampled to 3 mm resolution and used to create image-based dose distributions. Dose distributions and analysis were performed in MIM Software SurePlan TM utilizing SurePlan TM Local Deposition Method (LDM) and a dose convolution method (WFBH). We sought to implement a patient-specific background subtraction prior to dose calculation to make these noisy bremsstrahlung SPECT images suitable for post-TARE dosimetry. On average the percentage of mean background counts to maximum count in the image across all patients was 9.4 ± 4.9% (maximum = 7.6%, minimum = 2.3%). Absolute dose increased and profile line width decreased as background subtraction value increased. The average value of the LDM and WFBH dose methods was statistically the same. As background subtraction value increased, the DVH curves become unrealistic and distorted. Background subtraction on bremsstrahlung SPECT image has a large effect on post-TARE dosimetry. The background contour defined provides a systematic estimate to the activity background that accounts for the scanner and patient conditions at the time of the image study and is easily implemented using commercially available software. Using the mean count in the background contour as a subtraction across the entire image gave the most realistic dose distributions. This methodology is independent of microsphere and software manufacturer allowing for use with any available products or tools., (© 2021 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals LLC on behalf of American Association of Physicists in Medicine.)

Over the past decade, direct arylation polymerization (DArP) has emerged as a facile and sustainable methodology for the synthesis of conjugated polymers. Recently, we developed Cu-catalyzed DArP (Cu-DArP) as a low-cost, Pd-free synthetic pathway, which enables conjugated polymers to be synthesized with high molecular weights and minimization of defects. However, the lack of study on the use of Cu-precatalysts in small-molecule direct arylation poses significant limitations for Cu-DArP to potentially overtake conventional Pd-catalyzed methodology, such as the low solubility and stability of the previously employed CuI. Therefore, in this report, we decide to explore the utility of a well-defined, easy-to-prepare, highly soluble, and stable precatalyst, Cu(phen)(PPh 3 )Br, as an alternative to the CuI, 1,10-phenanthroline catalytic system previously used for Cu-DArP. Herein, we report a drastic improvement of Cu-DArP methodology for the synthesis of 5,5'-bithiazole (5-BTz)-based conjugated polymers enabled by an efficient precatalyst approach, affording polymers with good M n (up to 16.5 kDa) and excellent yields (up to 79%). 1 H NMR studies reveal the exclusion of homocoupling defects, which further verifies the excellent stability of Cu(phen)(PPh 3 )Br compared to CuI. Furthermore, we were able to decrease the catalyst loading from 15 mol % to only 5 mol % ( M n of 11.8 kDa, 64% yield), which is unprecedented when aryl bromides are employed for Cu-DArP. Significantly, 5-BTz was shown to be inactive under various of Pd-DArP conditions, which demonstrates the high compatibility of Cu-DArP as the only pathway for the C-H activation of the 5-BTz unit and a clear case demonstrating an advantage of Cu-DArP relative to Pd-DArP.

An artificial cornea or keratoprosthesis requires high mechanical strength, good biocompatibility, and sufficient wear and corrosion resistance to withstand the hostile environment. We report a reduced graphene oxide-reinforced titania-based composite for this application. Graphene oxide nanoparticles (GO) and liquid crystalline graphene oxide (LCGO) were the graphene precursors and mixed with titanium dioxide (TiO 2 ) powder. The composites reinforced with reduced GO or LCGO were produced through spark plasma sintering (SPS). The mechanical properties (Young's modulus and hardness), wear behaviour and corrosion resistance were studied using nanoindentation, anoidic polarization, long-term corrosion assay in artificial tear fluid and tribology assay in corroboration with atomic force microscopy and scanning electron microscopy. Biocompatibility was assessed by human corneal stromal cell attachment, survival and proliferation, and DNA damages. Sintered composites were implanted into rabbit corneas to assess for in vivo stability and host tissue responses. We showed that reduced graphene/TiO 2 hybrids were safe and biocompatible. In particular, the 1% reduced LCGO/TiO 2 (1rLCGO/TiO 2 ) composite was mechanically strong, chemically stable, and showed better wear and corrosion resistance than pure titania and other combinations of graphene-reinforced titania. Hence the 1rLCGO/ TiO 2 bioceramics can be a potential skirt biomaterial for keratoprosthesis to treat end-stage corneal blindness. STATEMENT OF SIGNIFICANCE: The osteo-odonto-keratoprosthesis (OOKP) is an artificial cornea procedure used to restore vision in end-stage corneal diseases, however it is contraindicated in young subjects, patients with advanced imflammatory diseases and posterior segment complications. Hence, there is a need of an improved keratoprosthesisskirt material with high mechanical and chemical stability, wear resistance and tissue integration ability. Our study characterized a reduced graphene oxide-reinforced titania-based biomaterial, which demonstrated strong mechanical strength, wear and corrosion resistance, and was safe and biocompatible to human corneal stromal cells. In vivo implantation to rabbit corneas did not cause any immune and inflammation outcomes. In conclusion, this invention is a potential keratoprosthesis skirt biomaterial to withstand the hostile environment in treating end-stage corneal blindness., (Copyright © 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Molecular orientation at the donor-acceptor interface plays a crucial role in determining the efficiency of organic semiconductor materials. We have used vibrational sum frequency generation spectroscopy to determine the orientation of poly-3-hexylthiophene (P3HT) at the planar buried interface with fullerene (C 60 ). The thiophene rings of P3HT have been found to tilt significantly toward C 60 , making an average angle θ ≈ 49° ± 10° between the plane of the ring and the interface. Such tilt may be attributed to π-π stacking interactions between P3HT and C 60 and may facilitate efficient charge transfer between donor and acceptor. Upon annealing, the thiophene rings tilt away from the interface by Δθ = 12-19°. This may be attributed to higher crystallinity of annealed P3HT that propagates all the way to the interface, resulting in more "edge-on" orientation, which is consistent with the observed red-shift by ∼6 cm -1 and spectral narrowing of the C=C stretch bands.

Direct arylation polymerization (DArP) has enabled the more sustainable synthesis of conjugated polymers through the reduction of waste, elimination of toxic and hazardous byproducts, and through the reduction of overall synthetic steps. However, DArP methodologies have almost exclusively relied on the use of noble metal catalysts, such as those with Pd, counter to the efforts toward sustainability. Herein, we report the optimized synthesis of a flourinated arylene conjugated copolymer via DArP using a low-cost, sustainable copper catalyst. Through optimization of the polymerization conditions, we are able to lower the loading of the catalyst from 50 to 5 mol %. As an example, we are able to obtain molecular weights of 16.4 kDa, accompanied by a yield of 54%, with a loading of only 5 mol % for the Cu catalyst. The synthesized polymers were characterized using 1 H and 19 F NMR spectroscopy, showing agreement with those previously prepared with a minimization or exclusion of defects. This work also demonstrates that Cu-catalyzed DArP methodologies can be compatible with substrates that do not possess directing groups, which can help to facilitate C-H functionalization, allowing for a broadening of substrate scope.

Nonconjugated electroactive polymers (also known as pendant or side-chain electroactive polymers) promise several potential advantages relative to conjugated polymers including enhanced mechanical durability, greater stability and synthesis via living polymerization techniques. However, most previous examples suffer from low charge carrier mobility. Here, using poly(2- N -carbazoylethyl acrylate) (PCzEA) as a model polymer, we investigate the ability of side-chain tacticity to influence hole mobility. Specifically, we investigated polymers with dyad isotacticity ( m ) ranging from ∼45 to ∼95% synthesized by several methods including free radical polymerization and anionic polymerization. We found that the hole mobility (μ h ) measured via the space charge limited current (SCLC) technique increased proportionally to the increasing isotacticity from 2.11 × 10 -6 cm 2 V -1 s -1 ( m = 45.5%) to 4.68 × 10 -5 cm 2 V -1 s -1 ( m = 94.7%) in unannealed samples and that mobilities could be boosted as high as 2.74 × 10 -4 cm 2 V -1 s -1 ( m = 94.7%) with thermal annealing, which rivaled the well-known conjugated polymer poly(3-hexylthiophene) (P3HT) (μ h = 5.8 × 10 -4 cm 2 V -1 s -1 ). As such, we report here clear experimental evidence that control of side chain tacticity can enhance charge carrier mobility in nonconjugated pendant electroactive polymers, converging with mobilities typically only observed in conjugated polymers.

An extensive family of semi-random polymers was prepared via Stille polycondensation with varying contents of alkyl spacers incorporated into the polymer backbone to serve as a break in conjugation. This family was investigated to determine the effect of alkyl spacer length and percent incorporation on the optical, electronic, and mechanical properties. The optical bandgap was found to steadily increase from 1.53 to 1.70 eV as the amount of spacer was increased from 10 mol percent to 40 mol percent while the length of the spacer had little to no effect. In space charge limited current (SCLC) carrier mobility measurements, hole mobility was found to decrease as the amount of spacer increased but was found to steadily increase as the length of the spacer was increased from 6 to 10 carbons. Mechanical properties were observed by film-on-elastomer and film-on-water measurements, with low elastic moduli and high ductility attributed both to the break in conjugation as well as the semi-random structure of the polymer backbone. Measurements of the mechanical properties using the buckling method revealed elastic moduli between 0.14 and 1.3 GPa, and several polymers, when bonded to an elastomeric substrate, could be stretched beyond 80% strain. These polymers were further tested as free-standing films by obtaining a pull test on the surface of water, where we obtained tensile moduli between 0.13 and 0.75 GPa. These results indicate that semi-random polymers with conjugation-break spacers are promising candidates for further study in flexible electronics.

The manufacture of mechanically strong and biocompatible titania (TiO 2 ) materials is of vital importance for their application as corneal implant skirts. This study was aimed at optimizing the selection of raw powder and sintering conditions for TiO 2 ceramics. TiO 2 compacts were synthesized from five raw powders, denoted as Altair, Inframat, Alfa, Materion, and Amperit, respectively, by spark plasma sintering using different sintering parameters. The XRD and Raman results confirmed that the anatase TiO 2 phase in the Inframat powder had converted completely to rutile TiO 2 phase after sintering at 900°C and above. The nanoindentation results indicated that among the five types of TiO 2 samples sintered at 1100°C, the Inframat pellets possessed the highest Young's modulus and hardness. Additionally, when Materion samples were employed to study the effects of SPS parameters, a higher sintering temperature in the range of 1100-1300°C decreased the mechanical properties of sintered pellets probably due to the generation of more structural defects. Culture of human corneal stromal fibroblasts on the sintered sample surfaces showed that comparably high cell viability and proliferation were observed on all TiO 2 samples except Amperit compared to positive control. Furthermore, cells cultured on Inframat TiO 2 sintered in the temperature range of 900-1300°C exhibited viability and formation of focal adhesion complex similar to those on control, and those prepared at 1100°C had significantly higher cell proliferation indices than control. In conclusion, Inframat TiO 2 consolidated at 1100°C by SPS was the best formulation for the preparation of mechanically strong and biocompatible Keratoprosthesis skirt. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3502-3513, 2017., (© 2017 Wiley Periodicals, Inc.)

Continuous flow methods are utilized in conjunction with direct arylation polymerization (DArP) for the scaled synthesis of the roll-to-roll compatible polymer, poly[(2,5-bis(2-hexyldecyloxy)phenylene)-alt-(4,7-di(thiophen-2-yl)-benzo[c][1,2,5]thiadiazole)] (PPDTBT). PPDTBT is based on simple, inexpensive, and scalable monomers using thienyl-flanked benzothiadiazole as the acceptor, which is the first β-unprotected substrate to be used in continuous flow via DArP, enabling critical evaluation of the suitability of this emerging synthetic method for minimizing defects and for the scaled synthesis of high-performance materials. To demonstrate the usefulness of the method, DArP-prepared PPDTBT via continuous flow synthesis is employed for the preparation of indium tin oxide (ITO)-free and flexible roll-coated solar cells to achieve a power conversion efficiency of 3.5% for 1 cm 2 devices, which is comparable to the performance of PPDTBT polymerized through Stille cross coupling. These efforts demonstrate the distinct advantages of the continuous flow protocol with DArP avoiding use of toxic tin chemicals, reducing the associated costs of polymer upscaling, and minimizing batch-to-batch variations for high-quality material., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Transparent bioceramics have attracted a large amount of research interest as they facilitate direct observation of biointerfacial reactions. Thus far, attempts to achieve transparent hydroxyapatite have been focused on augmenting the sintering pressure and/or extending the sintering duration. This study aims at fabricating transparent HA using a direct and fast spark plasma sintering process with appropriate starting powder and moderate sintering pressure. Three types of raw powder, namely micro-spheres, nano-rods and nano-spheres, were sintered to investigate the optical and biological properties of the compacted pellets. It was found that in terms of transparency, the micro-sphere pellet sintered at 1000°C stood out with an in-line transmittance as high as 84% achieved at 1300nm for a 2mm thick sample. In addition, pellets fabricated from micro-spheres demonstrated the highest cell viability in in vitro biological tests with L929 cells. Living cells cultured on a transparent micro-sphere pellet could be directly and clearly observed by light microscopy. It is thus concluded that the micro-sphere powder is the most desirable raw material to manufacture transparent hydroxyapatite because it could enable dense pellets with notably high transparency and outstanding in vitro biocompatibility to be readily obtained., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Neuromuscular junctions (NMJ) are specialized synapses that link motor neurons with muscle fibers. These sites are fundamental to human muscle activity, controlling swallowing and breathing amongst many other vital functions. Study of this synapse formation is an essential area in neuroscience; the understanding of how neurons interact and control their targets during development and regeneration are fundamental questions. Existing data reveals that during initial stages of development neurons target and form synapses driven by biophysical and biochemical cues, and during later stages they require electrical activity to develop their functional interactions. The aim of this study was to investigate the effect of exogenous electrical stimulation (ES) electrodes directly in contact with cells, on the number and size of acetylcholine receptor (AChR) clusters available for NMJ formation. We used a novel in vitro model that utilizes a flexible electrical stimulation system and allows the systematic testing of several stimulation parameters simultaneously as well as the use of alternative electrode materials such as conductive polymers to deliver the stimulation. Functionality of NMJs under our co-culture conditions was demonstrated by monitoring changes in the responses of primary myoblasts to chemical stimulants that specifically target neuronal signaling. Our results suggest that biphasic electrical stimulation at 250Hz, 100μs pulse width and current density of 1mA/cm 2 for 8h, applied via either gold-coated mylar or the conductive polymer PPy, significantly increased the number and size of AChRs clusters available for NMJ formation. This study supports the beneficial use of direct electrical stimulation as a strategic therapy for neuromuscular disorders., Statement of Significance: The beneficial effects of electrical stimulation (ES) on human cells in vitro and in vivo have long been known. Although the effects of stimulation are clear and the therapeutic benefits are known, no uniform parameters exist with regard to the duration, frequency and amplitude of the ES. To this end, we are answering several important questions on the parameters for ES of nerve and muscle monocultures and co-cultures by probing the effects on the enhancement of acetylcholine receptors (AChR) clustering available for neuromuscular junction formation using a conductive platform. This work opens the possibility to combine electrical stimulus delivered via conductive polymer substrates, from which biomolecules could also be delivered, providing opportunities to further enhance the therapeutic effect., (Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

It is challenging to obtain dense 45S5 Bioglass ® (45S5) with controlled crystallinity and satisfactory mechanical properties by conventional sintering processes due to its fast crystallization above the first glass transition temperature. Spark plasma sintering (SPS) has stood out in this respect by virtue of its capability to provide fast heating and densification rates. However, there have been insufficient investigations into the in vitro biological properties of 45S5 compacts obtained by SPS. In this study, we report the fabrication of fully densified 45S5 pellets in the temperature range of 500 °C-600 °C through a rapid SPS process (sintering for 3 min) as well as the assessment of the influence of sintering temperature and aqueous aging on the biological properties of sintered pellets with L929 and MG63 cells. The cell culture results showed that both extended ageing and a lower SPS temperature in the 500-600 °C range could generally lead to faster cell proliferation and higher cell viability. The former was possibly caused by the slower alkalization of the media during cell culture, and the latter may have resulted from the release of more Ca and Si ions. The pellet sintered at 550 °C without aqueous aging led to the highest ALP activity in MG63 cells, which may be attributed to the high interfacial pH at the pellet surface and the leaching of more Si ions. Therefore, dense 45S5 compacts with mild crystallinity consolidated by SPS at 550 °C is a promising candidate for orthopedic implants in loading bearing applications.

The compositional dependence of the open-circuit voltage (V oc ) in ternary blend bulk heterojunction (BHJ) solar cells is correlated with the miscibility of polymers, which may be influenced by a number of attributes, including crystallinity, the random copolymer effect, or surface energy. Four ternary blend systems featuring poly(3-hexylthiophene-co-3-(2-ethylhexyl)thiophene) (P3HT 75 -co-EHT 25 ), poly(3-hexylthiophene-co-(hexyl-3-carboxylate)), herein referred to as poly(3-hexylthiophene-co-3-hexylesterthiophene) (P3HT 50 -co-3HET 50 ), poly(3-hexylthiophene-thiophene-diketopyrrolopyrrole) (P3HTT-DPP-10%), and an analog of P3HTT-DPP-10% with 40% of 3-hexylthiophene exchanged for 2-(2-methoxyethoxy)ethylthiophen-2-yl (3MEO-T) (featuring an electronically decoupled oligoether side-chain), referred to as P3HTTDPP-MEO40%, are explored in this work. All four polymers are semicrystalline and rich in rr-P3HT content and perform well in binary devices with PC 61 BM. Except for P3HTTDPP-MEO40%, all polymers exhibit similar surface energies (∼21-22 mN/m). P3HTTDPP-MEO40% exhibits an elevated surface energy of around 26 mN/m. As a result, despite the similar optoelectronic properties and binary solar cell performance of P3HTTDPP-MEO40% compared to P3HTT-DPP-10%, the former exhibits a pinned V oc in two different sets of ternary blend devices. This is a stark contrast to previous rr-P3HT-based systems and demonstrates that surface energy, and its influence on miscibility, plays a critical role in the formation of organic alloys and can supersede the influence of crystallinity, the random copolymer effect, similar backbone structures, and HOMO/LUMO considerations. Therefore, we confirm surface energy compatibility as a figure-of-merit for predicting the compositional dependence of the V oc in ternary blend solar cells and highlight the importance of polymer miscibility in organic alloy formation.

Alkyl solubilizing side chains on conjugated polymers can serve as a handle for modifying polymer properties. Recently, oligo-ether and semifluoro alkyl side chains were utilized to tune the surface energy of random P3HT-based polymers without changing the optical and electronic properties. Here, this method is applied to semi-random poly(3-hexylthiophene-thiophene-diketopyrrolopyrrole) (P3HTT-DPP) and the subsequent polymer device, optical, electronic, structural, and thermal properties are characterized. P3HTMETT-DPP, bearing oligo-ether side chains, exhibited higher crystallinity, closer lamellar packing, and lower temperature thermal transitions. P3HTFHTT-DPP, featuring semifluoro alkyl side chains, presented reduced crystallinity, greater lamellar packing distances, and higher temperature thermal transitions. P3HTMETT-DPP performed similarly to P3HTT-DPP under identical processing conditions, whereas P3HTFHTT-DPP had greatly reduced J SC due to lower polymer concentration necessitated by solubility.

Tissue engineering scaffolds for nerve regeneration, or artificial nerve conduits, are particularly challenging due to the high level of complexity the structure of the nerve presents. The list of requirements for artificial nerve conduits is long and includes the ability to physically guide nerve growth using physical and chemical cues as well as electrical stimulation. Combining these characteristics into a conduit, while maintaining biocompatibility and biodegradability, has not been satisfactorily achieved by currently employed fabrication techniques. Here we present a method combining pultrusion and wet-spinning techniques facilitating incorporation of pre-formed filaments into ionically crosslinkable hydrogels. This new biofabrication technique allows the incorporation of conducting or drug-laden filaments, controlled guidance channels and living cells into hydrogels, creating new improved conduit designs.

We report the first use of spark plasma sintering (SPS) as a single-step process to achieve superhydrophobic reduced graphene oxide (rGO). It was found that SPS was capable of converting smooth and electrically insulating graphene oxide (GO) sheets into highly electrically conductive rGO with minimum residual oxygen and hierarchical roughness which could be well retained after prolonged ultrasonication. At a temperature of 500 °C, which is lower than the conventional critical temperature for GO exfoliation, GO was successfully exfoliated, reduced, and hierarchically roughened. rGO fabricated by only 1 min of treatment at 1050 °C was superhydrophobic with a surface roughness (Ra) 10 times as large as that of GO as well as an extraordinarily high C:O ratio of 83.03 (atom %) and water contact angle of 153°. This demonstrates that SPS is a superior GO reduction technique, which enabled superhydrophobic rGO to be quickly and effectively achieved in one single step. Moreover, the superhydrophobic rGO fabricated by SPS showed an impressive bacterial antifouling and inactivation effect against Escherichia coli in both aqueous solution and the solid state. It is envisioned that the superhydrophobic rGO obtained in this study can be potentially used for a wide range of industrial and biomedical applications, such as the fabrication of self-cleaning and antibacterial surfaces.

Continuous composite fibres composed of polypyrrole (PPy) nanoparticles and reduced graphene oxide (rGO) at different mass ratios were fabricated using a single step wet-spinning approach. The electrical conductivity of the composite fibres increased significantly with the addition of rGO. The mechanical properties of the composite fibres also improved by the addition of rGO sheets compared to fibres containing only PPy. The ultimate tensile strength of the fibres increased with the proportion of rGO mass present. The elongation at break was greatest for the composite fibre containing equal mass ratios of PPy nanoparticles and rGO sheets. L929 fibroblasts seeded onto fibres showed no reduction in cell viability. To further assess toxicity, cells were exposed to media that had been used to extract any aqueous-soluble leachates from developed fibre. Overall, these composite fibres show promising mechanical and electrical properties while not significantly impeding cell growth, opening up a wide range of potential applications including nerve and muscle regeneration studies.

The advent of implantable biomaterials has revolutionized medical treatment, allowing the development of the fields of tissue engineering and medical bionic devices (e.g., cochlea implants to restore hearing, vagus nerve stimulators to control Parkinson's disease, and cardiac pace makers). Similarly, future materials developments are likely to continue to drive development in treatment of disease and disability, or even enhancing human potential. The material requirements for implantable devices are stringent. In all cases they must be nontoxic and provide appropriate mechanical integrity for the application at hand. In the case of scaffolds for tissue regeneration, biodegradability in an appropriate time frame may be required, and for medical bionics electronic conductivity is essential. The emergence of graphene and graphene-family composites has resulted in materials and structures highly relevant to the expansion of the biomaterials inventory available for implantable medical devices. The rich chemistries available are able to ensure properties uncovered in the nanodomain are conveyed into the world of macroscopic devices. Here, the inherent properties of graphene, along with how graphene or structures containing it interface with living cells and the effect of electrical stimulation on nerves and cells, are reviewed., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Background: Universities should provide flexible and inclusive selection and admission policies to increase equity in access and outcomes for indigenous and ethnic minority students. This study investigates an equity-targeted admissions process, involving a Multiple Mini Interview and objective testing, advising Māori and Pacific students on their best starting point for academic success towards a career in medicine, nursing, health sciences and pharmacy., Methods: All Māori and Pacific Admission Scheme (MAPAS) interviewees enrolled in bridging/foundation or degree-level programmes at the University of Auckland were identified (2009 to 2012). Generalised linear regression models estimated the predicted effects of admission variables (e.g. MAPAS Maths Test; National Certificate in Educational Achievement (NCEA) Rank Score; Any 2 Sciences; Followed MAPAS Advice) on first year academic outcomes (i.e. Grade Point Average (GPA) and Passes All Courses) adjusting for MAPAS interview year, gender, ancestry and school decile., Results: 368 First Year Tertiary (bridging/foundation or degree-level) and 242 First Year Bachelor (degree-level only) students were investigated. NCEA Rank Score (estimate 0.26, CI: 0.18-0.34, p< 0.0001); MAPAS Advice Followed (1.26, CI: 0.18-1.34, p = 0.0002); Exposure to Any 2 Sciences (0.651, CI: 0.15-1.15, p = 0.012); and MAPAS Mathematics Test (0.14, CI: 0.02-0.26, p = 0.0186) variables were strongly associated with an increase in First Year Tertiary GPA. The odds of passing all courses in First Year Tertiary study was 5.4 times higher for students who Followed MAPAS Advice (CI: 2.35-12.39; p< 0.0001) and 2.3 times higher with Exposure to Any Two Sciences (CI: 1.15-4.60; p = 0.0186). First Year Bachelor students who Followed MAPAS Advice had an average GPA that was 1.1 points higher for all eight (CI: 0.45-1.73; p = 0.0009) and Core 4 courses (CI: 0.60-2.04; p = 0.0004)., Conclusions: The MAPAS admissions process was strongly associated with positive academic outcomes in the first year of tertiary study. Universities should invest in a comprehensive admissions process that includes alternative entry pathways for indigenous and ethnic minority applicants.

The brain is an enormously complex organ structured into various regions of layered tissue. Researchers have attempted to study the brain by modeling the architecture using two dimensional (2D) in vitro cell culturing methods. While those platforms attempt to mimic the in vivo environment, they do not truly resemble the three dimensional (3D) microstructure of neuronal tissues. Development of an accurate in vitro model of the brain remains a significant obstacle to our understanding of the functioning of the brain at the tissue or organ level. To address these obstacles, we demonstrate a new method to bioprint 3D brain-like structures consisting of discrete layers of primary neural cells encapsulated in hydrogels. Brain-like structures were constructed using a bio-ink consisting of a novel peptide-modified biopolymer, gellan gum-RGD (RGD-GG), combined with primary cortical neurons. The ink was optimized for a modified reactive printing process and developed for use in traditional cell culturing facilities without the need for extensive bioprinting equipment. Furthermore the peptide modification of the gellan gum hydrogel was found to have a profound positive effect on primary cell proliferation and network formation. The neural cell viability combined with the support of neural network formation demonstrated the cell supportive nature of the matrix. The facile ability to form discrete cell-containing layers validates the application of this novel printing technique to form complex, layered and viable 3D cell structures. These brain-like structures offer the opportunity to reproduce more accurate 3D in vitro microstructures with applications ranging from cell behavior studies to improving our understanding of brain injuries and neurodegenerative diseases., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Recent work has pointed to polymer miscibility and surface energy as key figures of merit in the formation of organic alloys and synergistic behavior between components in ternary blend solar cells. Here, we present a simple model system and first report of poly(3-hexylthiophene)-based random copolymers featuring either a semifluoroalkyl (P3HT - co - FHT) or oligoether (P3HT - co - MET) side chain, prepared via Stille polycondensation. Water drop contact angle measurements demonstrated that P3HT - co - FHT polymers reached a minimum surface energy of 14.2 mN/m at 50% composition of comonomers, while in contrast, P3HT - co - MET polymers increased as high as 27.0 mN/m at 50% composition, compared to P3HT at 19.9 mN/m. Importantly, the surface energy of the copolymers was found to vary regularly with comonomer composition and exhibited fine-tuning. Optical and electronic properties of the polymers are found to be composition independent as determined by UV-vis and CV measurements; HOMO energy levels ranged from 5.25 to 5.30 eV; and optical band gaps all measured 1.9 eV. Following this model, surface energy modification of state-of-the-art polymers, without altering desirable electronic and optical properties, is proposed as a useful tool in identifying and exploiting more alloying polymer pairs for ternary blend solar cells.

Arsenic-induced skin cancer is a significant global health burden. In areas with arsenic contamination of water sources, such as China, Pakistan, Myanmar, Cambodia and especially Bangladesh and West Bengal, large populations are at risk of arsenic-induced skin cancer. Arsenic acts as a co-carcinogen with ultraviolet (UV) radiation and affects DNA damage and repair. Nicotinamide (vitamin B3) reduces premalignant keratoses in sun-damaged skin, likely by prevention of UV-induced cellular energy depletion and enhancement of DNA repair. We investigated whether nicotinamide modifies DNA repair following exposure to UV radiation and sodium arsenite. HaCaT keratinocytes and ex vivo human skin were exposed to 2μM sodium arsenite and low dose (2J/cm2) solar-simulated UV, with and without nicotinamide supplementation. DNA photolesions in the form of 8-oxo-7,8-dihydro-2'-deoxyguanosine and cyclobutane pyrimidine dimers were detected by immunofluorescence. Arsenic exposure significantly increased levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine in irradiated cells. Nicotinamide reduced both types of photolesions in HaCaT keratinocytes and in ex vivo human skin, likely by enhancing DNA repair. These results demonstrate a reduction of two different photolesions over time in two different models in UV and arsenic exposed cells. Nicotinamide is a nontoxic, inexpensive agent with potential for chemoprevention of arsenic induced skin cancer.

Here two contrasting approaches to polymer-fullerene solar cells are compared. In the first approach, two distinct semi-random donor-acceptor copolymers are blended with phenyl-C61-butyric acid methyl ester (PC61BM) to form ternary blend solar cells. The two poly(3-hexylthiophene)-based polymers contain either the acceptor thienopyrroledione (TPD) or diketopyrrolopyrrole (DPP). In the second approach, semi-random donor-acceptor copolymers containing both TPD and DPP acceptors in the same polymer backbone, termed two-acceptor polymers, are blended with PC61BM to give binary blend solar cells. The two approaches result in bulk heterojunction solar cells that have the same molecular active-layer components but differ in the manner in which these molecular components are mixed, either by physical mixing (ternary blend) or chemical "mixing" in the two-acceptor (binary blend) case. Optical properties and photon-to-electron conversion efficiencies of the binary and ternary blends were found to have similar features and were described as a linear combination of the individual components. At the same time, significant differences were observed in the open-circuit voltage (Voc) behaviors of binary and ternary blend solar cells. While in case of two-acceptor polymers, the Voc was found to be in the range of 0.495-0.552 V, ternary blend solar cells showed behavior inherent to organic alloy formation, displaying an intermediate, composition-dependent and tunable Voc in the range from 0.582 to 0.684 V, significantly exceeding the values achieved in the two-acceptor containing binary blend solar cells. Despite the differences between the physical and chemical mixing approaches, both pathways provided solar cells with similar power conversion efficiencies, highlighting the advantages of both pathways toward highly efficient organic solar cells.