Unique Self-Phosphorylating Polybenzimidazole of the 6F Family for HT-PEM Fuel Cell Application.

High-temperature polymer-electrolyte membrane fuel cells (HT-PEMFCs) are a very important type of fuel cells since they operate at 150-200 °C, making it possible to use hydrogen contaminated with CO. However, the need to improve the stability and other properties of gas-diffusion electrodes still impedes their distribution. Self-supporting anodes based on carbon nanofibers (CNF) are prepared using the electrospinning method from a polyacrylonitrile solution containing zirconium salt, followed by pyrolysis. After the deposition of Pt nanoparticles on the CNF surface, the composite anodes are obtained. A new self-phosphorylating polybenzimidazole of the 6F family is applied to the Pt/CNF surface to improve the triple-phase boundary, gas transport, and proton conductivity of the anode. This polymer coating ensures a continuous interface between the anode and proton-conducting membrane. The polymer is investigated using CO2 adsorption, TGA, DTA, FTIR, GPC, and gas permeability measurements. The anodes are studied using SEM, HAADF STEM, and CV. The operation of the membrane-electrode assembly in the H2/air HT-PEMFC shows that the application of the new PBI of the 6F family with good gas permeability as a coating for the CNF anodes results in an enhancement of HT-PEMFC performance, reaching 500 mW/cm2 at 1.3 A/cm2 (at 180 °C), compared with the previously studied PBI-O-PhT-P polymer.

Alcohol withdrawal and pain: Peripheral mechanisms join central circuits.

Negative affective aspects of alcohol withdrawal and pain involve converging brain circuits. In this issue of Neuron, Son et al.1 identify a peripheral mechanism of an alcohol-withdrawal-induced headache-like condition, which is centered on mast-cell-specific receptor MrgprB2 activated by corticotropin-releasing factor (CRF) in dura mater to drive nociception.

Successful Treatment of Sebaceous Nevus With Copper Vapor Laser.

Introduction: Sebaceous nevus (SN) is a benign skin hamartoma with a potent transformation in benign or malignant tumors in adolescents or adults. Due to the most common location in the esthetic zone, an SN makes patients seek a dermatologist for cosmetic concerns on the face or neck. The surgical excision of a large-sized SN in the esthetic zone may require reconstruction with a skin flap and be associated with recurrences and scar formation. Case Report: We describe the successful treatment of the large-sized neck SN with copper vapor laser (CVL) for the first time. A left-sided neck SN (linear size of 27 mm) in the 24-year-old Caucasian female completely resolved after eight CVL sessions. The settings were as follows: average power accounted for 0.8-1.0 W, with a ratio at green (511 nm) and yellow (578 nm) wavelengths of 3:2. The pulse duration was set as 20 nanoseconds, the repetition rate 16.6 kHz, the exposure time 200 ms, light spot diameter of 1 mm. The CVL treatment resulted in the complete disappearance of the SN without remote side effects such as hyperpigmentation, scarring or recurrences 24 months after the treatment. The patient was satisfied with the excellent cosmetic results. Conclusion: The CVL treatment of the SN provides the most relevant result due to the complete elimination of SN cells and the remodeling of the vascular bed supplying the involved areas.

Hmgb1 Silencing in the Amygdala Inhibits Pain-Related Behaviors in a Rat Model of Neuropathic Pain.

Chronic pain presents a therapeutic challenge due to the highly complex interplay of sensory, emotional-affective and cognitive factors. The mechanisms of the transition from acute to chronic pain are not well understood. We hypothesized that neuroimmune mechanisms in the amygdala, a brain region involved in the emotional-affective component of pain and pain modulation, play an important role through high motility group box 1 (Hmgb1), a pro-inflammatory molecule that has been linked to neuroimmune signaling in spinal nociception. Transcriptomic analysis revealed an upregulation of Hmgb1 mRNA in the right but not left central nucleus of the amygdala (CeA) at the chronic stage of a spinal nerve ligation (SNL) rat model of neuropathic pain. Hmgb1 silencing with a stereotaxic injection of siRNA for Hmgb1 into the right CeA of adult male and female rats 1 week after (post-treatment), but not 2 weeks before (pre-treatment) SNL induction decreased mechanical hypersensitivity and emotional-affective responses, but not anxiety-like behaviors, measured 4 weeks after SNL. Immunohistochemical data suggest that neurons are a major source of Hmgb1 in the CeA. Therefore, Hmgb1 in the amygdala may contribute to the transition from acute to chronic neuropathic pain, and the inhibition of Hmgb1 at a subacute time point can mitigate neuropathic pain.

Structure and properties of naphthalene-diimide N-functionalized with stilbene.

Derivatives of naphthalene-diimide (NDI) are among the most studied and popular organic semiconductors showing n-type conductivity. However, the structure and optoelectronic properties of crystalline NDIs N-functionalized with conjugated donors have not been investigated yet. In this study, a novel donor-acceptor compound NDI-Stb bearing one NDI core, as an acceptor, and two stilbene moieties covalently linked via imide positions of NDI, as a donor, was synthesized. A combined experimental and theoretical approach was applied to study the structure and properties of NDI-Stb molecules and its crystals. We found and explained why optical absorption and high-frequency Raman spectra are inherited from those of donor and acceptor moieties, but photoluminescence is determined by the properties of the whole molecule. We resolved the structure of NDI-Stb single crystals and found that strong intermolecular interactions operate along two directions, for which NDI cores stack either on similar cores or on stilbene moieties. These interactions cause suppression of dynamic disorder indicated by a weak low-frequency Raman signal and solid-state luminescence enhancement. Ambipolar charge transport was predicted, and electron transport was experimentally observed in NDI-Stb polycrystalline thin films. The results obtained highlight the potential of using NDIs N-functionalized with conjugated donor moieties in optoelectronic applications, and improve the understanding of structure-property relationships necessary for the rational design of novel donor-acceptor organic semiconductors.

Self-Phosphorylated Polybenzimidazole: An Environmentally Friendly and Economical Approach for Hydrogen/Air High-Temperature Polymer-Electrolyte Membrane Fuel Cells.

The development of phosphorylated polybenzimidazoles (PBI) for high-temperature polymer-electrolyte membrane (HT-PEM) fuel cells is a challenge and can lead to a significant increase in the efficiency and long-term operability of fuel cells of this type. In this work, high molecular weight film-forming pre-polymers based on N1,N5-bis(3-methoxyphenyl)-1,2,4,5-benzenetetramine and [1,1'-biphenyl]-4,4'-dicarbonyl dichloride were obtained by polyamidation at room temperature for the first time. During thermal cyclization at 330-370 °C, such polyamides form N-methoxyphenyl substituted polybenzimidazoles for use as a proton-conducting membrane after doping by phosphoric acid for H2/air HT-PEM fuel cells. During operation in a membrane electrode assembly at 160-180 °C, PBI self-phosphorylation occurs due to the substitution of methoxy-groups. As a result, proton conductivity increases sharply, reaching 100 mS/cm. At the same time, the current-voltage characteristics of the fuel cell significantly exceed the power indicators of the commercial BASF Celtec® P1000 MEA. The achieved peak power is 680 mW/cm2 at 180 °C. The developed approach to the creation of effective self-phosphorylating PBI membranes can significantly reduce their cost and ensure the environmental friendliness of their production.

Proton-Conducting Polymer-Coated Carbon Nanofiber Mats for Pt-Anodes of High-Temperature Polymer-Electrolyte Membrane Fuel Cell.

High-temperature polymer-electrolyte membrane fuel cells (HT-PEM FC) are a very important type of fuel cell since they operate at 150-200 °C, allowing the use of hydrogen contaminated with CO. However, the need to improve stability and other properties of gas diffusion electrodes still hinders their distribution. Anodes based on a mat (self-supporting entire non-woven nanofiber material) of carbon nanofibers (CNF) were prepared by the electrospinning method from a polyacrylonitrile solution followed by thermal stabilization and pyrolysis of the mat. To improve their proton conductivity, Zr salt was introduced into the electrospinning solution. As a result, after subsequent deposition of Pt-nanoparticles, Zr-containing composite anodes were obtained. To improve the proton conductivity of the nanofiber surface of the composite anode and reach HT-PEMFC better performance, dilute solutions of Nafion®, a polymer of intrinsic microporosity (PIM-1) and N-ethyl phosphonated polybenzimidazole (PBI-OPhT-P) were used to coat the CNF surface for the first time. These anodes were studied by electron microscopy and tested in membrane-electrode assembly for H2/air HT-PEMFC. The use of CNF anodes coated with PBI-OPhT-P has been shown to improve the HT-PEMFC performance.

Development of High-Performance Hydrogen-Air Fuel Cell with Flourine-Free Sulfonated Co-Polynaphthoyleneimide Membrane.

This paper presents research on the technological development of hydrogen-air fuel cells with high output power characteristics using fluorine-free co-polynaphtoyleneimide (co-PNIS) membranes. It is found that the optimal operating temperature of a fuel cell based on a co-PNIS membrane with the hydrophilic/hydrophobic blocks = 70/30 composition is in the range of 60-65 °C. The maximum output power of a membrane-electrode assembly (MEA), created according to the developed technology, is 535 mW/cm2, and the working power (at the cell voltage of 0.6 V) is 415 mW/cm2. A comparison with similar characteristics of MEAs based on a commercial Nafion 212 membrane shows that the values of operating performance are almost the same, and the maximum MEA output power of a fluorine-free membrane is only ~20% lower. It was concluded that the developed technology allows one to create competitive fuel cells based on a fluorine-free, cost-effective co-polynaphthoyleneimide membrane.

Hydrophobic-Hydrophilic Properties and Characterization of PIM-1 Films Treated by Elemental Fluorine in Liquid Perfluorodecalin.

A direct fluorination technique was applied for the surface treatment of PIM-1 films in a liquid phase (perfluorodecalin). The fluorinated samples were analyzed by various instrumental techniques. ATR-IR spectroscopy showed that the fluorination predominantly takes place in methylene- and methyl-groups. Cyano-groups, aromatic hydrogens and the aromatic structure of the PIM-1 repeat unit were shown to be relatively stable at the fluorination conditions. XPS confirmed that the concentration of fluorine, as well as oxygen, in the near surface layer (~1 nm) increases with fluorination time. C1s and O1s surface spectra of the fluorinated PIM-1 samples indicated an appearance of newly-formed C-F and C-O functional groups. Scanning electron microscopy and X-ray energy-dispersive spectroscopy of the fluorinated PIM-1 samples showed an increase of the fluorine concentration at the surface (~0.1-1 µm) with the treatment duration. Analysis of the slices of the PIM-1 films demonstrated a decline of the fluorine content within several microns of the film depth. The decline increased with the fluorination time. A model of fluorine concentration dependence on the film depth and treatment duration was suggested. A change in the specific free surface energy as a result of PIM-1 fluorination was revealed. The fluorination time was shown to affect the surface energy (γSV), providing its shift from a low value (25 mJ∙m-2), corresponding to tetrafluoroethylene, up to a relatively high value, corresponding to a hydrophilic surface.

Effect of Organo-Silanes Structure on the Properties of Silane-Crosslinked Membranes Based on Cardo Polybenzimidazole PBI-O-PhT.

Polybenzimidazoles (PBI) doped with phosphoric acid (PA) are promising electrolytes for medium temperature fuel cells. Their significant disadvantage is a partial or complete loss of mechanical properties and an increase in hydrogen permeability at elevated temperatures. Covalent silanol crosslinking is one possible way to stabilize PBI membranes in the presence of PA. Three organo-substituted silanes, namely (3-Bromopropyl)trimethoxysilane (SiBr), trimethoxy [2-(7-oxabicyclo [4.1.0]hept-3-yl)ethyl]silane (Si-biC) and (3-Glycidyloxypropyl)trimethoxysilane (KH 560), were used as covalent crosslinkers of PBI-O-PhT in order to determine the effect of the silane structure and crosslinking degree on membrane properties. The crosslinking degree was 1-50%. All crosslinked membranes were characterized by impedance and IR-spectroscopy. The mechanical properties, morphology, stability and hydrogen permeability of the membranes were determined. In the case of silanes with linear substituents (SiBr, KH 560), a denser structure is formed, which is characterized by greater oxidative stability and lower hydrogen permeability in comparison to the silane with a bulk group. All the crosslinked membranes have a higher mechanical strength compared with the initial PBI-O-PhT membrane both before and after doping with PA. Despite the hardening of the polymer matrix of the membranes, their proton conductivity changes insignificantly. It was shown that cross-linked membranes can be used in fuel cells.

High Molecular Weight AB-Polybenzimidazole and Its Solutions in a Complex Organic Solvent: Dissolution Kinetics and Rheology.

AB-polybenzimidazole (ABPBI) dissolution kinetics in an eco-friendly complex acid-free solvent based on dimethyl sulfoxide (DMSO), methanol and KOH, and the rheological behavior of their solutions are investigated. The optimal component ratio of solvent providing the complete ABPBI dissolution is determined. Methanol containing dissolved KOH contributes to the creation of a single-phase superbasic medium, which accelerates and improves the polymer solubility in a mixture with DMSO, significantly reducing the viscoelasticity of the resulting solution. The optimum methanol content is up to 60 wt.% related to DMSO. The polymer dissolution rate increases by 5 times in this composition. It found the polymer concentration of 9% is close to the dissolution limit due to the strong solution structuring, which is probably associated with an increase in the amount of water released during the KOH-methanol-DMSO interactions. As a result, the conditions for obtaining high concentrated solutions in a complex, mainly organic solvent for fiber spinning are developed. The viscoelastic properties of solutions are measured in the concentration range of 1-9% at temperatures of 20-50 °C. The flow activation energy for 7 and 9% solutions decreases by 1.5 and 2.3 times, respectively, as the content of methanol in the complex solvent increases from 10 to 60%.

Cardo Polybenzimidazole (PBI-O-PhT) Based Membrane Reinforced with m-polybenzimidazole Electrospun Nanofiber Mat for HT-PEM Fuel Cell Applications.

The further development of high temperature polymer electrolyte membrane (HT-PEM) fuel cells largely depends on the improvement of all components of the membrane-electrode assembly (MEA), especially membranes and electrodes. To improve the membrane characteristics, the cardo-polybenzimidazole (PBI-O-PhT)-based polymer electrolyte complex doped with phosphoric acid is reinforced using an electrospun m-PBI mat. As a result, the PBI-O-PhT/es-m-PBInet · nH3PO4 reinforced membrane is obtained with hydrogen crossover values (~0.2 mA cm-2 atm-1), one order of magnitude lower than the one of the initial PBI-O-PhT membrane (~3 mA cm-2 atm-1) during HT-PEM fuel cell operation with Celtec®P1000 electrodes at 180 °C. Just as importantly, the reinforced membrane resistance was very close to the original one (65-75 mΩ cm2 compared to ~60 mΩ cm2). A stress test that consisted of 20 start-stops, which included cooling to the room temperature and heating back to 180 °C, was applied to the MEAs with the reinforced membrane. More stable operation for the HT-PEM fuel cell was shown when the Celtec®P1000 cathode (based on carbon black) was replaced with the carbon nanofiber cathode (based on the pyrolyzed polyacrylonitrile electrospun nanofiber mat). The obtained data confirm the enhanced characteristics of the PBI-O-PhT/es-m-PBInet · nH3PO4 reinforced membrane.

Numerical Modeling of The Dysplastic Vessel Heating in PWS by Yellow 578 nm Copper Vapor Laser Radiation for Different Skin Phototypes.

Introduction: Many clinical studies and protocols have been written about laser treatment for fair skin phototypes. However, for dark-skinned phototypes, information is limited, and the risk of burns is higher, especially if the same settings are recommended for fair skin. Competitive epidermal melanin absorption decreases the light energy reaching dysplastic vessels in a port-wine stain (PWS), preventing the vessel from achieving the temperature of the desired clinical result. Therefore, the choice of safe laser settings for different skin phototypes can be realized using numerical modeling of PWS vessel heating. This study aimed to demonstrate the algorithm for choosing both effective and safe photodestruction of dilated dermal vessels in PWS with the copper vapor laser (CVL) at 578 nm for different skin phototypes. Methods: We used the multilayered skin model with different melanin content for detecting the safe laser parameters for PWS treatment. The calculation of the selective heating of the vascular component with CVL radiation at yellow 578-nm wavelengths for different skin phototypes was performed via Matlab mathematical programming system and its application Femlab for solving partial differential equations using the Finite element method. Results: We determined the location, depth, and size of blood vessels that could be selectively heated to coagulation temperature for different skin prototypes. CVL fluence values need to be reduced almost two times for skin phototype IV than for skin phototype II to provide safe CVL treatment. The maximum depth of the location of the vessels, which can be selectively heated to coagulation temperature, also decreased for dark skin phototypes. Histological and histochemical findings validated the results of our calculations. Conclusion: To our knowledge, the use of numerical simulation to optimize has not yet been considered. According to our calculations, CVL could selectively heat the dilated vessel, which occurred in purple and proliferative-type PWS for dark skin at the reduced fluence range and depth.

Water Sorption by Polyheteroarylenes.

The sorption-diffusion characteristics of rigid-chain glassy polymers based on polyheteroarylenes (PHAs) have been studied in a wide interval of relative humidity and temperatures of thermal treatment of the polymer sorbents. Experimental data on water vapor sorption for polynaphthoyleneimidobenzimidazole (PNIB) and its copolymers with different chemical nature have been obtained. Water diffusion coefficients have been calculated, and parameters of their concentration and temperature dependences have been determined. It was found that water molecules sorbed by PNIB and its copolymers are strongly bounded. Water mobile and cluster states depend on the structure of macromolecules and thermal prehistory of polymer sorbents. It is shown that the translational coefficients of water diffusion for all PHAs are in the range from 10-9 to 10-8 cm2/s. The diffusion coefficients also increase slightly with temperature increasing, and their general dependence on temperature is satisfactorily described by the Arrhenius equation. The average activation energy of water diffusion varies from 24.3 to 25.9 kJ/mol. The hydrate numbers of rigid-chain PHAs functional groups have been determined. The above-mentioned results allow us to predict the sorption properties of heterocyclic macromolecular sorbents with complex chain architecture.

Some Specifics of Defect-Free Poly-(o-aminophenylene)naphthoylenimide Fibers Preparation by Wet Spinning.

A series of model experiments were carried out on drops of poly-(o-aminophenylene)naphthoylenimide (PANI-O) solutions in N-methyl-2-pyrrolidone (NMP) surrounded by a coagulant of different compositions as starting points of defect-free fibers spinning by the wet method. An influence of compositions of dopes and multicomponent coagulants on the diffusion kinetics and drop morphology during coagulation has been investigated. It is shown that the defining parameters of the coagulation process are viscoelastic properties of the polymer solution and the diffusion activity of the coagulant, meaning not only the rate of coagulation but also the presence/absence of macro defects in the resulting fiber. The optimal morphology of as-spun fibers is obtained by coagulation of solution in a three-component mixture containing solvent and two precipitants of different activity (water and ethanol). The chosen coagulating mixture was used for the fiber spinning of PANI-O with different molecular weights dopes, and fibers with sufficiently high strength (~250 MPa), moduli (~2.1 MPa), and elongation at break (50%) were obtained.

Sex Differences in the Brain Transcriptome Related to Alcohol Effects and Alcohol Use Disorder.

There is compelling evidence that sex and gender have crucial roles in excessive alcohol (ethanol) consumption. Here, we review some of the data from the perspective of brain transcriptional differences between males and females, focusing on rodent animal models. A key emerging transcriptional feature is the role of neuroimmune processes. Microglia are the resident neuroimmune cells in the brain and exhibit substantial functional differences between males and females. Selective breeding for binge ethanol consumption and the impacts of chronic ethanol consumption and withdrawal from chronic ethanol exposure all demonstrate sex-dependent neuroimmune signatures. A focus is on resolving sex-dependent differences in transcriptional responses to ethanol at the neurocircuitry level. Sex-dependent transcriptional differences are found in the extended amygdala and the nucleus accumbens. Telescoping of ethanol consumption is found in some, but not all, studies to be more prevalent in females. Recent transcriptional studies suggest that some sex differences may be due to female-dependent remodeling of the primary cilium. An interesting theme appears to be developing: at least from the animal model perspective, even when males and females are phenotypically similar, they differ significantly at the level of the transcriptome.

The Successful Treatment of Eyelid Intradermal Melanocytic Nevi (Nevus of Miescher)With the Dual-Wavelengths Copper Vapor Laser.

Introduction: Surgical methods for removing eyelid nevus are associated with a risk of developing such side effects as scarring or loss of eyelashes. Although current laser modalities have shown promising results, eyelid laser surgery may cause skin discoloration and noticeable scarring. This study aims at evaluating the efficacy and safety of the dual-wavelengths copper vapor laser (CVL) treatment of eyelid intradermal nevus of Miescher (NM). Patients and Methods: We present three adult female patients with eyelid intradermal nevus treated with CVL. CVL settings were as follows: the average power of 0.6-0.8 W, under a power ratio of 3:2 at wavelengths of 511 nm and 578 nm, exposure time of 0.3 seconds, the light spot diameter of 1 mm. Results: The dual-wavelength CVL treatment of medium- and large-sized NM provides the complete removal of eyelid dome-like NM after one and two sessions with a month interval correspondingly. The duration of skin healing accounted for two weeks. Conclusion: The complete removal of eyelid NM lesions without side effects demonstrates the safety and efficacy of dual-wavelengths CVL in treating such skin lesions. This laser treatment mode of benign skin neoplasms seems promising for dermatologists and cosmetologists' clinical practice.