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Active transcutaneous bone conduction (BC) devices offer the benefit of improved power output compared to passive transcutaneous devices and remove the risk of skin infections that are more common in traditional percutaneous BC devices. Despite these advantages, more research is needed on implant location, device coupling, and their influence on device performance. This study is aimed at quantifying the extent to which certain parameters affect device output when using the Osia® system actuator. Parameters under study are (1) implant location, (2) comparison with the actuator of a state-of-the-art BC device, (3) bone undergrowth simulation, and (4) skull fixation. Five human cadaveric heads were implanted with the actuator at three different implant locations: (1) recommended, (2) posterior Osia® positions, and (3) standard Baha® position. At each location, the cochlear promontory velocity and the intracochlear pressure difference were measured. A percutaneous bone conduction actuator was used as a reference for the obtained measurements. Stimulation levels corresponded to a hearing level of 60 dB HL for frequencies between 250 and 6000 Hz. In addition, bone cement was used as a simulation for reactive bone growth. Results obtained in four heads indicate an improved power transmission of the transcutaneous actuator when implanted at the recommended position compared to the actuator of the percutaneous device on its respective recommended location when stimulating at an identical force level. A correlation was found between the promontory vibration and the actuator position, indicating that the same level of stimulation leads to higher promontory vibrations when the device is implanted closer to the ear canal. This is mainly reflected at frequencies higher than 1 kHz, where an increase was observed in both measurement modalities. At lower frequencies (

In this article, we report on the development of a catheter-based, biomimetic sensor as a step toward a minimally invasive diagnostic instrument in the context of functional bowel disorders. Histamine is a key mediator in allergic and inflammatory processes in the small intestines; however, it is a challenge to determine histamine levels at the duodenal mucosa, and classical bioreceptors are unsuitable for use in the digestive medium of bowel fluid. Therefore, we have developed molecularly imprinted polypyrrole coatings for impedimetric sensing electrodes, which enable the quantification of histamine in nondiluted, human bowel fluid in a broad concentration range from 25 nM to 1 mu M. The electrodes show negligible cross-sensitivity to histidine as a competitor molecule and, for comparison, we also evaluated the response of nonimprinted and taurine-imprinted polypyrrole to histamine. Furthermore, using equivalent-circuit modeling, we found that the molecular recognition of histamine by polypyrrole primarily increases the resistive component of the electrode-liquid interface while capacitive effects are negligible. The sensor, integrated into a catheter, measures differentially to correct for nonspecific adsorption effects in the complex matrix of bowel fluids, and a single triggering frequency is sufficient to determine histamine concentrations. Together, these features are beneficial for real-time diagnostic tests.

Advancements in intracochlear diagnostics, as well as prosthetic and regenerative innerear therapies, rely on a good understanding of cochlear microanatomy. The human cochlea is verysmall and deeply embedded within the densest skull bone, making nondestructive visualization of itsinternal microstructures extremely challenging. Current imaging techniques used in clinical practice,such as MRI and CT, fall short in their resolution to visualize important intracochlear landmarks, andhistological analysis of the cochlea cannot be performed on living patients without compromisingtheir hearing. Recently, optical coherence tomography (OCT) has been shown to be a promisingtool for nondestructive micrometer resolution imaging of the mammalian inner ear. Various studiesperformed on human cadaveric tissue and living animals demonstrated the ability of OCT to visualizeimportant cochlear microstructures (scalae, organ of Corti, spiral ligament, and osseous spiral lamina)at micrometer resolution. However, the interpretation of human intracochlear OCT images is non-trivial for researchers and clinicians who are not yet familiar with this novel technology. In thisstudy, we present an atlas of intracochlear OCT images, which were acquired in a series of 7 freshand 10 fresh-frozen human cadaveric cochleae through the round window membrane and describethe qualitative characteristics of visualized intracochlear structures. Likewise, we describe severalintracochlear abnormalities, which could be detected with OCT and are relevant for clinical practice. ispartof: Journal Of Clinical Medicine vol:12 issue:1 ispartof: location:Switzerland status: Published online

BACKGROUND: The generally accepted method to assess the functionality of novel bone conduction implants in a preclinical stage is to experimentally measure the vibratory response of the cochlear promontory. Yet, bone conduction of sound is a complex propagation phenomenon, depending on both frequency and amplitude, involving different conduction pathways. OBJECTIVES: The aim of this study is to validate the use of intracochlear sound pressure (ICP) as an objective indicator for perceived loudness for bone conduction stimulation. It is investigated whether a correlation exists between intracochlear sound pressure measurements in cadaveric temporal bones and clinically obtained results using the outcome of a loudness balancing experiment. METHODS: Ten normal hearing subjects were asked to balance the perceived loudness between air conducted (AC) sound and bone conducted (BC) sound by changing the AC stimulus. Mean balanced thresholds were calculated and used as stimulation levels in a cadaver trial (N = 4) where intracochlear sound pressure was measured during AC and BC stimulation to assess the correlation with the measured clinical data. The intracochlear pressure was measured at the relatively low stimulation amplitude of 80 dBHL using a lock-in amplification technique. RESULTS: Applying AC and BC stimulation at equal perceived loudness on cadaveric heads yield a similar differential intracochlear pressure, with differences between AC and BC falling within the range of variability of normal hearing test subjects. CONCLUSION: Comparing the perceived loudness at 80 dB HL for both AC and BC validates intracochlear pressure as an objective indicator of the cochlear drive. The measurement setup is more time-intensive than measuring the vibratory response of the cochlear promontory, yet it provides direct information on the level of the cochlear scalae. ispartof: Hearing Research vol:422 ispartof: location:Netherlands status: Published online

This work details the acquisition, handling, and measurement of microliters of perilymph, the fluid inside the human hearing organ, using dielectric relaxation spectroscopy and the correlation of the molecular relaxations to the physiological composition. Comparing between ex-vivo fresh, fresh-frozen and fixed sources reveals that dielectric absorption of the pulses is due to alpha- and beta- charge transfer relaxation related to the geometry of white blood cells, lymphocytes, in the perilymph. Interestingly, comparing the presence of molecular relaxations and the amplitude of dielectric absorption, perilymph obtained from fixed temporal bones matches fresh perilymph better than when obtained from fresh frozen source, due to the importance of well-preserved cell geometry. ispartof: Ieee Transactions On Dielectrics And Electrical Insulation vol:28 issue:3 pages:932-937 status: published

The local and cooperative dynamics of atactic PS (a- PS) were studied by broadband dielectric relaxation spectroscopy (BDRS) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). The a-PS has been subjected to thermal rejuvenation and subsequent quenching, short-term aging (6 weeks), and long-term aging (1 year) at ambient conditions. Where for the rejuvenated sample only an α- and a γ-relaxation is observed, short-term aging results in an additional β*-relaxation that merges with the α-relaxation at longer aging times. The γ-relaxation is increasing in intensity and activation energy during aging. The α-process shows no spectral changes and shift in the relaxation time upon aging. This may be attributed to a possible erasure of history of the material during the temperature-sweep mode measurement. Fourier transform infrared spectroscopy (FTIR) results suggest that the energetically favorable trans-trans (tt) conformers are increased in population with aging. ispartof: JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS vol:57 issue:20 pages:1394-1401 status: published

The effect of plastic deformation on the molecular dynamics of atactic polystyrene (a-PS) was studied by broadband dielectric relaxation spectroscopy (BDRS), Fourier-transform infrared spectroscopy (FTIR) and polarized-light microscopy. Sheets of a-PS have been subjected to cold rolling, that is, mechanical rejuvenation, followed by a quenching step and fast heating above its glass-transition temperature, resulting in thermal rejuvenation. Cold rolling revealed, in addition to the known α- and γ(I)-relaxations, four hitherto unknown relaxation processes (II, III, IV and V). Using the framework of craze formation and multiplicity of the glass transition (E. Donth, G. H. Michler, Colloid Polym. Sci. 1989, 267, 557–567), supported by an activation-enthalpy/entropy analysis (Starkweather, W. Howard, Macromolecules 1981, 14, 1277–1281), the following physical picture emerges: (a) processes I and II represent local conformation transitions γ referring to chains of two different degrees of stretching (T/G-ratio); and (ii) processes III and IV were identified as helix-inversion processes of T2G2 helices as reported earlier for syndiotactic-rich PS—an assignment supported by FTIR results. Finally, the relaxation V could be attributed to the onset of the fibrillar glass transition (within crazes), leading to stress release by collapse of the fibrils and hence dying out of process V. Polarized-light microscopy confirmed the creation of oriented structures and internal stresses upon cold rolling, and their removal upon thermal rejuvenation.

The protic ionic liquid diethylmethylammonium methanesulfonate ([DEMA][OMs]) was analyzed in depth by differential scanning calorimetry (DSC), nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy and broadband dielectric spectroscopy (BDS) under anhydrous conditions. Karl Fischer titration, NMR and FT-IR spectra confirmed the high purity of [DEMA][OMs]. The melting point (37.7 °C) and the freezing point (14.0 °C) obtained by DSC agree well with the values determined by BDS (40.0 °C and 14.0 °C). The dc conductivity (σdc) above the melting/freezing point obeys Vogel-Fulcher-Tammann (VFT) equation well and thus the proton conduction in [DEMA][OMs] is assumed to be dominated by the vehicle mechanism. In contrast, the σdc below the melting/freezing point can be fitted by the Arrhenius equation separately and therefore the proton conduction is most likely governed by the proton-hopping mechanism. The non-negligible influence of previously reported low water contents on the physicochemical properties of [DEMA][OMs] is found, indicating the importance of reducing water content as much as possible for the study of “intrinsic” properties of protic ionic liquids. ispartof: Journal Of Chemical Physics vol:152 issue:23 ispartof: location:United States status: Published online

In this work, we report on the development of a catheter-based sensor designed for measuring the concentration of histamine in the human duodenum. Certain gut disorders, such as the irritable bowel syndrome (IBS), are associated with elevated levels of intestinal histamine due to chronic immune activation. As it is still impossible to determine histamine concentrations in vivo, a nasointestinal catheter with histamine-sensing capabilities has the potential to become a valuable diagnostic instrument. Regarding the sensing principle, we selected impedance spectroscopy using voltages that are compatible with intra-body applications with molecularly imprinted polymers (MIPs) as recognition elements. MIPs are synthetic receptors that offer the advantages of robustness, high specificity and selectivity for histamine as a target. In this specific case, the MIPs were synthesized from acryclic acid monomers, which guarantees a uniform binding capacity within the pH range of intestinal fluid. We have validated the catheter sensor on human intestinal liquids spiked with histamine in a testing setup that mimics the environment inside the duodenum. The dose-response curves show an analytical range between 5 and 200 nM of histamine, corresponding to physiologically normal conditions while higher concentrations correlate with disease. The key output signal of the sensor is the resistive component of the MIP-functionalized titanium electrodes as derived from the equivalent-circuit modelling of full-range impedance spectra. Future applications could be catheters tailored to cardiovascular, urological, gastrointestinal, and neurovascular applications. This, in combination with the versatility of the MIPs, will make this sensor platform a versatile diagnostic tool.

Extending the well-established laser intensity modulation method (LIMM) by means of sequential frequency modulation represents a new approach for obtaining polarization depth profiles at both high spatial (nanometer) and temporal (millisecond) resolution. Thin films of the archetypal, organic, ferroelectric copolymer poly(vinylidene fluoride-co-trifluoroethylene) P(VDF-TrFE) were investigated in this manner to assess local switching kinetics. For subcoercive field conditions of 5 MV/m, the central regions of 2000 nm thick samples show a “bulk”-like, uniform polarization switching behaviour at a time-scale of 250 ms. In contrast, a 100 nm thick region near the metal-polymer interface reveals clear deviations from bulk switching kinetics. This likely reflects local charge generation/injection and trapping effects.

In this work, we present a new technique for the sensitive and facile detection of Saccharomyces strains with a detection limit of 30 cells/mL in both buffer solution and food samples such as beer and yoghurt. This is achieved by combining ultrathin surface-imprinted polymer (SIP) layers as receptors with impedance spectroscopy as the readout principle. Binding of cells to the imprinted polymer surface results in a concentration-dependent increase of the impedance signal. According to the equivalent-circuit modelling of the impedance spectra, this is due to an increase of the resistive component of the solid-liquid interface while capacitive effects are negligible. Regarding selectivity, we prepared imprints with three different template strains and compared the sensor response for using the same three strains as targets. The response is strongest for combinations in which templates and targets belong to the same strain. For other situations, the sensor signal is reduced by a factor of three, indicating a certain level of selectivity, which can be interpreted in terms of size and cell wall differences. In summary, the combination of SIP-type receptors with impedance spectroscopy offers a fast and sensitive technique for on-site analysis of complex food matrices outside a laboratory environment. The results for yeast should be transferable to other microorganisms, including pathogenic ones.

The human cochlea is deeply embedded in the temporal bone and surrounded by a thick otic capsule, rendering its internal structure inaccessible for direct visualization. Clinical imaging techniques fall short of their resolution for imaging of the intracochlear structures with sufficient detail. As a result, there is a lack of knowledge concerning best practice for intracochlear therapy placement, such as cochlear implantation. In the past decades, optical coherence tomography (OCT) has proven valuable for non-invasive, high-resolution, cross-sectional imaging of tissue microstructure in various fields of medicine, including ophthalmology, cardiology and dermatology. There is an upcoming interest for OCT imaging of the cochlea, which so far was mostly carried out in small animals. In this temporal bone study, we focused on high-resolution imaging of the human cochlea. The cochlea was approached through mastoidectomy and posterior tympanotomy, both standard surgical procedures. A commercially available spectral-domain OCT imaging system was used to obtain high-resolution images of the cochlear hook region through the intact round window membrane in four cadaveric human temporal bones. We discuss the qualitative and quantitative characteristics of intracochlear structures on OCT images and their importance for cochlear implant surgery. ispartof: SCIENTIFIC REPORTS vol:9 issue:1 ispartof: location:England status: published

HYPOTHESIS: Intracochlear pressure (ICP) measurements during bone conduction (BC) stimulation may be affected by motion of the pressure sensor relative to the cochlear promontory bone, demonstrating the need to cement the sensor firmly to the cochlear bone. BACKGROUND: ICP is a promising measurement tool for investigating the cochlear drive in BC transmission, but its use is not yet standardized. Previous ICP studies have reported artificially increased pressure due to motion of the sensor relative to the temporal bone. The artifact can be reduced by firmly cementing the sensor to the bone, but this is destructive for the sensor. Previous studies used a custom-made sensor; the use of commercially available sensors, however, is more generic, but also more challenging to combine with the cement. Therefore, the goals of the current study are: firstly, to evaluate a non-destructive cementing method suitable for a commercially available sensor, and secondly, to investigate ICP measurements during BC stimulation in more detail. METHODS: To study the effect of sensor cementing, three fixation conditions were investigated on six fresh-frozen temporal bones: 1) alginate, 2) alginate and dental composite, 3) alginate and dental composite, released from micromanipulators. Pressures in scala tympani and vestibuli were measured simultaneously, while velocity measurements were performed on the cochlear promontory and sensor. The ratio between sensor and promontory bone velocity was computed to quantify the relative motion. RESULTS: For air conduction stimulation, results were in line with those from previous ICP studies, indicating that baseline measurements were valid and could be used to interpret the results obtained with BC stimulation. Results showed that cementing the sensors and releasing them from the micromanipulators is crucial for valid ICP measurements. When the sensors were only sealed with alginate, the pressure was overestimated, especially at low and mid-frequencies. When the sensors were cemented and held in the micromanipulators, the pressure was underestimated. Compared with the scala tympani measurements, ICP measurements showed a lower scala vestibuli pressure below 1 kHz, and a higher pressure above 1 kHz. CONCLUSION: Dental composite is effective as a cement to attach commercially available sensors to the cochlear promontory bone. When sensors are firmly attached, valid ICP measurements can be obtained with BC stimulation. ispartof: OTOLOGY & NEUROTOLOGY vol:40 issue:9 pages:E858-E867 ispartof: location:PEOPLES R CHINA, Shanghai status: published

We disclose a supramolecular material that combines semiconducting and dipolar functionalities. The material consists of a discotic semiconducting carbonyl-bridged triarylamine core, which is surrounded by three dipolar amide groups. In thin films, the material self-organizes in a hexagonal columnar fashion through Jr-stacking of the molecular core and hydrogen bonding between the amide groups. Alignment by an electrical field in a simple metal/semiconductor/metal geometry induces a polar order in the interface layers near the metal contacts that can be reversibly switched, while the bulk material remains nonpolarized. On suitably chosen electrodes, the presence of an interfacial polarization field leads to a modulation of the barrier for charge injection into the semiconductor. Consequently, a reversible switching is possible between a high-resistance, injection-limited off-state and a low-resistance, space-charge-limited on-state. The resulting memory diode shows switchable rectification with on/off ratios of up to two orders of magnitude. This demonstrated multifunctionality of a single material is a promising concept toward possible application in lowcost, large-area, nonvolatile organic memories. Funding Agencies|NWO Nano program; Bavarian State Ministry of Science, Research, and the Arts for the Collaborative Research Network Solar Technologies go Hybrid; Deutsche Forschungsgemeinschaft (DFG) [SFB 953]; Vetenskapsradet [2015-03813]

Scanning Pyroelectric Microscopy (SPEM) at micrometer resolutions has been employed to study permanent polarity and its spatial organization in various insect wings containing chitin, one of the most abundant biopolymers. Both measurements on wings of houseflies and wasps revealed a well defined pyroelectric response, showing a multidomain polarization pattern at several length scales, from millimeter sized domains in the wing veins, to 20 micrometer sized domains in the membranes. The size of the smaller domains correlates well with the average chitin fiber length of 18 micrometers.

The concept of charge polarization coupling in the ferroelectric copolymer PVDF TrFE(poly[(vinylidene fluoride co trifluoroethylene]) has been revisited by employing high resolution (

Bio-organic materials such as bones, teeth, and tendon generally show nonlinear optical (Masters and So in Handbook of Biomedical Nonlinear Optical Microscopy, 2008), pyro- and piezoelectric (Fukada and Yasuda in J Phys Soc Jpn 12:1158, 1957) properties, implying a permanent polarization, the presence of which can be rationalized by describing the growth of the sample and the creation of a polar axis according to Markov’s theory of stochastic processes (Hulliger in Biophys J 84:3501, 2003; Batagiannis et al. in Curr Opin Solid State Mater Sci 17:107, 2010). Two proven, versatile techniques for probing spontaneous polarization distributions in solids are scanning pyroelectric microscopy (SPEM) and second harmonic generation microscopy (SHGM). The combination of pyroelectric scanning with SHG-microscopy in a single experimental setup leading to complementary pyroelectric and nonlinear optical data is demonstrated, providing us with a more complete image of the polarization in organic materials. Crystals consisting of a known polar and hyperpolarizable material, CNS (4-chloro-4\('\)-nitrostilbene) are used as a reference sample, to verify the functionality of the setup, with both SPEM and SHGM images revealing the same polarization domain information. In contrast, feline and human nails exhibit a pyroelectric response, but a second harmonic response is absent for both keratin containing materials, implying that there may be symmetry-allowed SHG, but with very inefficient second harmonophores. This new approach to polarity detection provides additional information on the polar and hyperpolar nature in a variety of (bio) materials.

The processes used to create synthetic spider silk greatly affect the properties of the produced fibers. This paper investigates the effect of process variations during artificial spinning on the thermal and mechanical properties of the produced silk. Property values are also compared to the ones of the natural dragline silk of the Nephila clavipes spider, and to unprocessed (as-spun) synthetic silk. Structural characterization by scanning pyroelectric microscopy is employed to provide insight into the axial orientation of the crystalline regions of the fiber and is supported by X-ray diffraction data. The results show that stretching and passage through liquid baths induce crystal formation and axial alignment in synthetic fibers, but with different structural organization than natural silks. Furthermore, an increase in thermal diffusivity and elastic modulus is observed with decreasing fiber diameter, trending toward properties of natural fiber. This effect seems to be related to silk fibers being subjected to a radial gradient during production. (Figure presented.).

We investigate the polarization loss in the archetypical molecular organic ferroelectric trialkylbenzene-1,3,5-tricarboxamide (BTA). We prove that the polarization loss is due to thermally activated Rrelaxation, which is a collective reversal of the amide dipole moments in ferroelectric domains. By applying a weak electrostatic field both the polarization loss and the R-relaxation are suppressed, leading to an enhancement of the retention time by at least several orders of magnitude. Alternative loss mechanisms are discussed and ruled out. By operating the thin-film devices slightly above the crystalline to liquid crystalline phase transition temperature the retention time of one compound becomes more than 12 hours even in absence of supportive bias, which is among the longest reported so far for organic ferroelectric materials. crosscheck: This document is CrossCheck deposited related_data: Supplementary Information identifier: M. Wübbenhorst (ORCID) identifier: M. Wübbenhorst (ResearcherID) identifier: R. P. Sijbesma (ORCID) identifier: M. Kemerink (ORCID) identifier: M. Kemerink (ResearcherID) copyright_licence: The PCCP Owner Societies have an exclusive publication licence for this journal copyright_licence: This article is freely available. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence (CC BY 3.0) history: Received 23 November 2016; Accepted 23 December 2016; Accepted Manuscript published 23 December 2016; Advance Article published 13 January 2017; Version of Record published 25 January 2017 ispartof: Physical Chemistry Chemical Physics vol:19 issue:4 pages:3192-3200 ispartof: location:England status: published

Polar metal–organic frameworks have potential applications as functional non-linear optical, piezoelectric, pyroelectric and ferroelectric materials. Using second harmonic generation microscopy we found that fluoride doping of the microporous iron(III) terephthalate MOF MIL-53(Fe) induces a polar organization in its structure, which was not previously detected with XRD. The polar order is only observed when both fluoride and guest molecules are present, and may be related to a complex interplay between the adsorbates and the framework, leading to a modification of the positioning of fluoride in the inorganic Fe-chains. Combined polarized second harmonic generation microscopy and scanning pyroelectric microscopy show that the polar axis is unidirectional and of the same sense over the whole crystal, extending up to 100 micrometers. This finding shows how MOF materials can be endowed with useful properties by doping MOFs with fluoride. crosscheck: This document is CrossCheck deposited related_data: Supplementary Information identifier: Karen Markey (ORCID) copyright_licence: The Royal Society of Chemistry has an exclusive publication licence for this journal copyright_licence: This article is freely available. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence (CC BY 3.0) history: Received 26 November 2015; Accepted 18 January 2016; Accepted Manuscript published 18 January 2016; Advance Article published 26 January 2016; Version of Record published 1 March 2016 ispartof: Dalton Transactions vol:45 issue:10 pages:4401-4406 ispartof: location:England status: published

We have investigated the ferroelectric polarization switching properties of trialkylbenzene-1,3,5 tricarboxamide (BTA), which is a model system for a large class of novel organic ferroelectric materials. In the solid state BTAs form a liquid crystalline columnar hexagonal phase that provides long range order that was previously shown to give rise to hysteretic dipolar switching. In this work the nature of the polar switching process is investigated by a combination of dielectric relaxation spectroscopy, depth-resolved pyroelectric response measurements, and classical frequency- and time-dependent electrical switching. We show that BTAs, when brought in a homeotropically aligned hexagonal liquid crystalline phase, are truly ferroelectric. Analysis of the transient switching behavior suggests that the ferroelectric switching is limited by a highly dispersive nucleation process, giving rise to a wide distribution of switching times. crosscheck: This document is CrossCheck deposited related_data: Supplementary Information identifier: R. P. Sijbesma (ORCID) identifier: M. Kemerink (ResearcherID) copyright_licence: The PCCP Owner Societies have an exclusive publication licence for this journal copyright_licence: This article is freely available. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence (CC BY 3.0) history: Received 2 June 2016; Accepted 3 August 2016; Accepted Manuscript published 3 August 2016; Advance Article published 11 August 2016; Version of Record published 24 August 2016 ispartof: Physical Chemistry Chemical Physics vol:18 issue:34 pages:23663-23672 ispartof: location:England status: published

Protic organic ionic plastic crystals (POIPCs) are a type of novel solid-state proton conductors. In this work, guanidinium nonaflate ([Gdm-H][NfO]) is reported to be a model POIPC. Its structure–property relationship has been investigated comprehensively. Infrared analysis of [Gdm-H][NfO] and its deuterated analogue [Gdm-D][NfO] confirms the complete formation of the protic salts. The cations in as-prepared [Gdm-D][NfO] are estimated to consist of [C(ND2)2(NHD)]+ and [C(ND2)3]+ with a molar ratio of around 1:1. The deuteration also proves that each guanidinium cation has six displaceable protons. Thermogravimetric analysis demonstrates that [Gdm-H][NfO] exhibits superior thermal stability in both nitrogen and air atmospheres. Isothermogravimetric analysis reveals its negligible vapor pressure with an estimated high enthalpy of vaporization (120.9 kJ mol−1). Differential scanning calorimetry measurements of [Gdm-H][NfO] show four evident endothermic peaks prior to its melting transition at 186.2 °C with a low entropy of melting (17.70 J K−1 mol−1). Shortly before the onset temperature of melting transition (186.2 °C), partial melting (partial liquefaction) was observed via polarized optical microscopy in the temperature region of 176–186 °C while the reason for partial melting of ionic plastic crystals is not clear yet. Variable-temperature powder X-ray diffraction tests confirm the related solid-solid phase transitions and demonstrate that [Gdm-H][NfO] exhibits short-range disorder and long-range positional order in the plastic crystalline phases. Dielectric spectroscopy measurements show that its ionic conductivity reaches 2.1 × 10−3 S cm−1 at 185 °C. The proton conduction in the plastic crystalline phases of [Gdm-H][NfO] is assumed to happen via the vehicle mechanism. In the molten state, the proton conduction follows a combination of the vehicle mechanism and the Grotthuss mechanism (structural diffusion). In summary, due to their exceptional physicochemical properties, POIPCs like [Gdm-H][NfO] are promising electrolyte materials for high temperature (100–200 °C) proton exchange membrane fuel cells. In addition, POIPC-based solid-state proton conductors are also expected to find applications in sensors and other electrochemical devices crosscheck: This document is CrossCheck deposited related_data: Supplementary Information identifier: Haolin Tang (ORCID) copyright_licence: The Royal Society of Chemistry has an exclusive publication licence for this journal copyright_licence: This article is freely available. This article is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported Licence (CC BY-NC 3.0) history: Received 29 June 2016; Accepted 7 July 2016; Accepted Manuscript published 8 July 2016; Advance Article published 21 July 2016; Version of Record published 2 August 2016 ispartof: Journal of Materials Chemistry A vol:4 issue:31 pages:12241-12252 status: published

The correspondence of the state of alignment of macromolecules in biomimetic materials and natural tissues is demonstrated by investigating a mechanism of electrical polarity formation: An in vitro grown biomimetic FAp/gelatin composite is investigated for its polar properties by second harmonic (SHGM) and scanning pyroelectric microscopy (SPEM). Hexagonal prismatic seed crystals formed in gelatin gels represent a monodomain polar state, due to aligned mineralized gelatin molecules. Later growth stages, showing dumbbell morphologies, develop into a bipolar state because of surface recognition by gelatin functionality: A reversal of the polar alignment of macromolecules, thus, takes place close to that basal plane of the seed. In natural hard tissues (teeth and bone investigated by SPEM) and the biomimetic FAp/gelatin composite, we find a surprising analogy in view of growth-induced states of polarity: The development of polarity in vivo and in vitro can be explained by a Markov-type mechanism of molecular recognition during the attachment of macromolecules.

To observe the pyroelectric response of bio-organic materials, several innovations have been proposed and implemented to push the sensitivity limits of a Scanning PyroElectric Microscope (SPEM). These include the use of noise reducing software, interdigitated comb electrodes instead of parallel plate electrodes and the use of rotating mirrors. Using these suggested techniques, the general performance of a SPEM measurement has been improved and allows the successful study of materials with a naturally weak spontaneous polarization and thus extremely low pyroelectric coefficients. ispartof: IEEE Transactions on Dielectrics and Electrical Insulation vol:19 issue:4 pages:1186-1190 status: published

Recently [S. Capponi, S. Napolitano, and M. Wubbenhorst, Nat. Commun. 3, 1233 (2012)], vapor deposited glasses of glycerol have been found to recover their super-cooled liquid state via a metastable, ordered liquid (MROL) state characterized by a tremendously enhanced dielectric strength along with a slow-down of the relaxation rate of the structural relaxation. To study the calorimetric signature of this phenomenon, we have implemented a chip-based, differential AC calorimeter in an organic molecular beam deposition setup, which allows the simultaneous measurement of dielectric relaxations via interdigitated comb electrodes and specific heat relaxation spectra during deposition and as function of the temperature. Heating of the as-deposited glass just above the bulk Tg and subsequent cooling/reheating revealed a step-wise increase in cp by in total 9%, indicating unambiguously that glycerol, through slow vapour deposition, forms a thermodynamically stable glass, which has a specific heat as low as that of crystalline glycerol. Moreover, these glasses were found to show excellent kinetic stability as well as evidenced by both a high onset-temperature and quasi-isothermal recovery measurements at -75 °C. The second goal of the study was to elucidate the impact of the MROL state on the specific heat and its relaxation to the super-cooled state. Conversion of "MROL glycerol" to its "normal" (ordinary liquid, OL) state revealed a second, small (∼2%) increase of the glassy cp, a little gain (

Bio-organic materials such as bones, teeth and tendon generally show pyro- and piezoelectric activity that implies the existence of macroscopic polarity. The first discoveries date from 1957 1 in the bones and tendon of both humans and animals and has led to the suggestion that the presence of spontaneous polarity might play a crucial role during morphogenesis and could facilitate other biological functions. © 2011 IEEE. ispartof: pages:75-76 ispartof: 2011 14th international symposium on electrets (ise) pages:75-76 ispartof: 14th International Symposium on Electrets (ISE) Montpellier, FRANCE, AUG 28-31, 2011 location:FRANCE, Montpellier date:28 Aug - 31 Aug 2011 status: published