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High-entropy alloy (HEA) nanocrystals have attracted extensive attention in catalysis. However, there are no effective strategies for synthesizing them in a controllable and predictable manner. With quinary HEA nanocrystals made of platinum-group metals as an example, we demonstrate that their structures with spatial compositions can be predicted by quantitatively knowing the reduction kinetics of metal precursors and entropy of mixing in the nanocrystals under dropwise addition of the mixing five–metal precursor solution. The time to reach a steady state for each precursor plays a pivotal role in determining the structures of HEA nanocrystals with homogeneous alloy and core-shell features. Compared to the commercial platinum/carbon and phase-separated counterparts, the dendritic HEA nanocrystals with a defect-rich surface show substantial enhancement in catalytic activity and durability toward both hydrogen evolution and oxidation. This quantitative study will lead to a paradigm shift in the design of HEA nanocrystals, pushing away from the trial-and-error approach.

Glutamatergic synapses display variable strength and diverse short-term plasticity (STP), even for a given type of connection. Using nonnegative tensor factorization and conventional state modeling, we demonstrate that a kinetic scheme consisting of two sequential and reversible steps of release–machinery assembly and a final step of synaptic vesicle (SV) fusion reproduces STP and its diversity among synapses. Analyzing transmission at the calyx of Held synapses reveals that differences in synaptic strength and STP are not primarily caused by variable fusion probability ( p fusion ) but are determined by the fraction of docked synaptic vesicles equipped with a mature release machinery. Our simulations show that traditional quantal analysis methods do not necessarily report p fusion of SVs with a mature release machinery but reflect both p fusion and the distribution between mature and immature priming states at rest. Thus, the approach holds promise for a better mechanistic dissection of the roles of presynaptic proteins in the sequence of SV docking, two-step priming, and fusion. It suggests a mechanism for activity-induced redistribution of synaptic efficacy.

The use of crystal engineering to control the supramolecular arrangement of π-conjugated molecules in the solid-state is of considerable interest for the development of novel organic electronic materials. In the present study, we investigated the effect of combining of two types of supramolecular interactions with different geometric requirements, amide hydrogen bonding and π-interactions, on the π-overlap between calamitic π-conjugated cores. To this end, we prepared two series of bithiophene diesters and diamides with methylene, ethylene, or propylene spacers between the bithiophene core and the functional groups in their terminal substituents. The hydrogen-bonded bithiophene diamides showed significantly denser packing of the bithiophene cores than the diesters and other known α,ω-disubstituted bithiophenes. The bithiophene packing density reach a maximum in the bithiophene diamide with an ethylene spacer, which featured the smallest longitudinal bithiophene displacement and infinite 1D arrays of electronically conjugated, parallel, and almost linear N-H···O=C hydrogen bonds. The synergistic hydrogen bonding and π-interactions were attributed to the favorable conformational mechanics of the ethylene spacer and resulted in H-type spectroscopic aggregates in solid-state absorption spectroscopy. These results demonstrate that the optoelectronic properties of π-conjugated materials in the solid-state may be tailored systematically via side chain engineering, and hence that this approach has significant potential for the design of organic and polymer semiconductors.

The mechanism of aggregation-induced emission, which overcomes the common aggregation-caused quenching problem in organic optoelectronics, is revealed by monitoring the real time structural evolution and dynamics of electronic excited state with frequency and polarization resolved ultrafast UV/IR spectroscopy and theoretical calculations. The formation of Woodward-Hoffmann cyclic intermediates upon ultraviolet excitation is observed in dilute solutions of tetraphenylethylene and its derivatives but not in their respective solid. The ultrafast cyclization provides an efficient nonradiative relaxation pathway through crossing a conical intersection. Without such a reaction mechanism, the electronic excitation is preserved in the molecular solids and the molecule fluoresces efficiently, aided by the very slow intermolecular charge and energy transfers due to the well separated molecular packing arrangement. The mechanisms can be general for tuning the properties of chromophores in different phases for various important applications.

During ongoing presynaptic action potential (AP) firing, transmitter release is limited by the availability of release-ready synaptic vesicles (SVs). The rate of SV recruitment (SVR) to release sites is strongly upregulated at high AP frequencies to balance SV consumption. We show that Munc13-1—an essential SV priming protein—regulates SVR via a Ca2+-phospholipid-dependent mechanism. Using knockin mouse lines with point mutations in the Ca2+-phospholipid-binding C2B domain of Munc13-1, we demonstrate that abolishing Ca2+-phospholipid binding increases synaptic depression, slows recovery of synaptic strength after SV pool depletion, and reduces temporal fidelity of synaptic transmission, while increased Ca2+-phospholipid binding has the opposite effects. Thus, Ca2+-phospholipid binding to the Munc13-1-C2B domain accelerates SVR, reduces short-term synaptic depression, and increases the endurance and temporal fidelity of neurotransmission, demonstrating that Munc13-1 is a core vesicle priming hub that adjusts SV re-supply to demand.

Glass transition temperature, Tg, is the key quantity for assessing morphological stability and molecular ordering of films of organic semiconductors. A reliable prediction of Tg from the chemical structure is, however, challenging, as it is sensitive to both molecular interactions and analysis of the heating or cooling process. By combining a fitting protocol with an automated workflow for forcefield parameterization, we predict Tg with a mean absolute error of ~20 °C for a set of organic compounds with Tg in the 50–230 °C range. Our study establishes a reliable and automated prescreening procedure for the design of amorphous organic semiconductors, essential for the optimization and development of organic light-emitting diodes.

本文首先釐清「通過／不通過制」（Pass/Fail，簡稱P/F制）的學習評量方式與「百分制」和「等第制」之異同，以及P/F制與成績平均積點（grade point average，簡稱GPA）的關係，並且呈現P/F制在臺灣高等教育發展上與零學分課程之間的緊密連結。接著，從學分與授課的對應關係，說明「服務學習」、「教學實務與實習」與「外語能力檢定」此三種零學分課程如何誤用P/F制，並指出其中的可能弊端以及背後的政策思維。從教育政策的角度觀察，P/F制與其他評量方式各有利弊得失。在提示P/F制的適用課程、對象與階段的理論基礎上，本 文主張多元的學習規劃設計，建議大學可從多元的學習評量方式著手，重塑教學管理的方向，期能更加符合適才適所的教育精神。 In this paper, we argue for the misuse of pass/fail grading system (P/F) in Taiwan’s zero-credit courses and depict the potential drawbacks and the thinking behind such policies. We first clarify the similarities and differences between P/F and other grading systems and explain the relationship between P/F and grade point average (GPA). We then reveal the close connection between P/F and the development of zero-credit courses in Taiwan’s university education. Based on the correspondence between credits and credit hours, we further demonstrate how P/F is seriously misused in the zero-credit courses of “service-learning”, “internship and practice of teaching”, and “graduation requirement of foreign language proficiency” and point out their possible drawbacks and the thinking behind such policies. From the perspective of education policies, P/F, like other grading systems, has its advantages and disadvantages. Building on the discussion of the theoretical foundation of P/F’s suitability and applicability in terms of courses, participants, and learning phases, we propose a diversified approach towards designing learning planning. We thus further suggest that by considering a diversified range of grading possibilities, universities can reshape the direction of course management to better facilitate students’ individual educational goals.

A recent implementation of time-dependent tight-binding density functional theory is employed in excited state molecular dynamics for the investigation of the fluorescence quenching mechanism in 3 prototypical aggregation-induced emission systems. An assessment of the accuracy of the electronic structure method is done by comparison with previous theoretical work while dynamics simulations were extended to the condensed phase to obtain excited state lifetimes comparable to experiment. A thorough investigation is done on tetraphenylethylene in order to resolve the on-going debate on the role of specific deactivation mechanisms. Both gas phase and solvent dynamics were computed for fulvene and silole derivatives.

Summary During ongoing presynaptic action potential (AP) firing, transmitter release is limited by the availability of release-ready synaptic vesicles (SVs). The rate of SV recruitment (SVR) to release sites is strongly upregulated at high AP frequencies to balance SV consumption. We show that Munc13-1—an essential SV priming protein—regulates SVR via a Ca2+-phospholipid-dependent mechanism. Using knockin mouse lines with point mutations in the Ca2+-phospholipid-binding C2B domain of Munc13-1, we demonstrate that abolishing Ca2+-phospholipid binding increases synaptic depression, slows recovery of synaptic strength after SV pool depletion, and reduces temporal fidelity of synaptic transmission, while increased Ca2+-phospholipid binding has the opposite effects. Thus, Ca2+-phospholipid binding to the Munc13-1-C2B domain accelerates SVR, reduces short-term synaptic depression, and increases the endurance and temporal fidelity of neurotransmission, demonstrating that Munc13-1 is a core vesicle priming hub that adjusts SV re-supply to demand., Graphical abstract, Highlights • The Munc13-1 C2B domain controls synaptic vesicle replenishment rates • Blocking Ca2+-phospholipid-C2B signaling attenuates vesicle replenishment • Enhancing Ca2+-phospholipid-C2B signaling accelerates vesicle replenishment • This process determines short-term plasticity and fidelity of synaptic transmission, Using novel knockin mouse models, Lipstein et al. show that Ca2+-phospholipid binding activates the presynaptic protein Munc13-1 to fine-tune the rate of synaptic vesicle replenishment according to synaptic activity. This process determines short-term synaptic plasticity and the temporal fidelity of synaptic transmission in the auditory brainstem and the hippocampus.

Despite organic/inorganic lead halide perovskite solar cells becoming one of the most promising next‐generation photovoltaic materials, instability under heat and light soaking remains unsolved. In this work, a highly hydrophobic cation, perfluorobenzylammonium iodide (5FBzAI), is designed and a 2D perovskite with reinforced intermolecular interactions is engineered, providing improved passivation at the interface that reduces charge recombination and enhances cell stability compared with benchmark 2D systems. Motivated by the strong halogen bond interaction, (5FBzAI)2PbI4 used as a capping layer aligns in in‐plane crystal orientation, inducing a reproducible increase of ≈60 mV in the V oc, a twofold improvement compared with its analogous monofluorinated phenylethylammonium iodide (PEAI) recently reported. This endows the system with high power conversion efficiency of 21.65% and extended operational stability after 1100 h of continuous illumination, outlining directions for future work., 2D perovskites are of great importance to increase both the efficiency and stability of perovskite interfaces. Motivated by the stronger halogen bond interaction, (5FBzAI)2PbI4 used as a capping layer in 3D/2D systems self‐organizes with an in‐plane crystal orientation, inducing a reproducible increase of ≈60 mV in the V oc, and remarkable operational stability.

Background The production of large quantities of cardiomyocyte is essential for the needs of cellular therapies. This study describes the selection of a human-induced pluripotent cell (hiPSC) line suitable for production of cardiomyocytes in a fully integrated bioprocess of stem cell expansion and differentiation in microcarrier stirred tank reactor. Methods Five hiPSC lines were evaluated first for their cardiac differentiation efficiency in monolayer cultures followed by their expansion and differentiation compatibility in microcarrier (MC) cultures under continuous stirring conditions. Results Three cell lines were highly cardiogenic but only one (FR202) of them was successfully expanded on continuous stirring MC cultures. FR202 was thus selected for cardiac differentiation in a 22-day integrated bioprocess under continuous stirring in a stirred tank bioreactor. In summary, we integrated a MC-based hiPSC expansion (phase 1), CHIR99021-induced cardiomyocyte differentiation step (phase 2), purification using the lactate-based treatment (phase 3) and cell recovery step (phase 4) into one process in one bioreactor, under restricted oxygen control (6 cells/mL) was achieved in the expansion phase. By controlling the stirring speed and DO levels in the bioreactor cultures, 7.36 ± 1.2 × 106 cells/mL cardiomyocytes with > 80% Troponin T were generated in the CHIR99021-induced differentiation phase. By adding lactate in glucose-free purification media, the purity of cardiomyocytes was enhanced (> 90% Troponin T), with minor cell loss as indicated by the increase in sub-G1 phase and the decrease of aggregate sizes. Lastly, we found that the recovery period is important for generating purer and functional cardiomyocytes (> 96% Troponin T). Three independent runs in a 300-ml working volume confirmed the robustness of this process. Conclusion A streamlined and controllable platform for large quantity manufacturing of pure functional atrial, ventricular and nodal cardiomyocytes on MCs in conventional-type stirred tank bioreactors was established, which can be further scaled up and translated to a good manufacturing practice-compliant production process, to fulfill the quantity requirements of the cellular therapeutic industry.

The use of methane as one of the cleanest energy sources has attracted significant public awareness, and methane production processes with less environmental impact than fracking are receiving considerable attention. Catalytic hydrocracking of plastic materials has been considered a potential clean alternative. However, catalysts that convert heterogeneous plastic feeds into a single product under industrially relevant conditions are lacking. Here, we describe a Ru-modified zeolite that catalytically transforms polyethylene, polypropylene, and polystyrene into grid-compatible methane (>97% purity), at 300 degrees C-350 degrees C using near-stoichiometric amounts of H-2. Mechanistic studies reveal a chain-end initiation process with limited isomerization of plastic substrates. A Ru site-dominant mechanism is proposed based on these studies and density functional theory (DFT) computations. We foresee that such a plastic-to-methane process may increase the intelligent use of plastic waste via energy recovery. There is also the potential to accommodate emerging sustainable H-2 production into existing natural gas networks, while integrating waste management, fuel production, and energy storage.

Supplementary Table S1. List of antibodies used in the study.

A.M. has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 844655 (SMOLAC). This publication is based on work supported by the KAUST Office of Sponsored Research (OSR) under award nos. OSR-2018-CARF/CCF-3079 and OSR-CRG2018-3746. D.A. also acknowledges the KAUST PSE Division for hosting his sabbatical in the framework of the Division's Visiting Faculty program. D.A. acknowledges funding by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) for financial support through the collaborative research centers TRR 146, SPP 2196, and grant number 460766640. K.-H.L. acknowledges the financial support from the Swiss NSF Early Postdoc Mobility fellowship (grant no. P2ELP2_195156). The authors thank Kostas Daoulas, Leanne Paterson, and Naoimi Kinaret for fruitful discussions and proof-reading of the manuscript. Open access funding enabled and organized by Projekt DEAL.

Amorphous small-molecule organic materials are utilized in organic light emitting diodes (OLEDs), with device performance relying on appropriate chemical design. Due to the vast number of contending materials, a symbiotic experimental and simulation approach would be greatly beneficial in linking chemical structure to macroscopic material properties. We review simulation approaches proposed for predicting macroscopic properties. We then present a library of OLED hosts, containing input files, results of simulations, and experimentally measured references of quantities relevant to OLED materials. We find that there is a linear proportionality between simulated and measured glass transition temperatures, despite a quantitative disagreement. Computed ionization energies are in excellent agreement with the ultraviolet photoelectron and photoemission spectroscopy in air measurements. We also observe a linear correlation between calculated electron affinities and ionization energies and cyclic voltammetry measurements. Computed energetic disorder correlates well with thermally stimulated luminescence measurements and charge mobilities agree remarkably well with space charge–limited current measurements. For the studied host materials, we find that the energetic disorder has the greatest impact on the charge carrier mobility. Our library helps to swiftly evaluate properties of new OLED materials by providing well-defined structural building blocks. The library is public and open for improvements. We envision the library expanding and the workflow providing guidance for future OLED material design.

Truxene and its derivatives have been extensively employed for various applications and are considered as promising dopant-free hole transport materials (HTMs) in perovskite solar cells (PSCs). Yet, a systematic exploration of their performance for this specific application remain lacking. Here, multiscale simulations are used to investigate the key structure-property relationships of truxene derivatives featuring distinct variations to the parent core. Specifically, the role of heteroatoms, alkyl chains, and substitution site on the most relevant electronic, transport, and stability properties to high-performing PSCs are assessed. Our findings demonstrate that each of the considered truxenes are potential alternatives to the current state-of-the-art HTM Spiro-OMeTAD.

Many aspects of short-term synaptic plasticity (STP) are controlled by relatively slow changes in the presynaptic intracellular concentration of free calcium ions ([Ca2+]i) that occur in the time range of a few milliseconds to several seconds. In nerve terminals, [Ca2+]i equilibrates diffusionally during such slow changes, such that the globally measured, residual [Ca2+]i that persists after the collapse of local domains is often the appropriate parameter governing STP. Here, we study activity-dependent dynamic changes in global [Ca2+]i at the rat calyx of Held nerve terminal in acute brainstem slices using patch-clamp and microfluorimetry. We use low concentrations of a low-affinity Ca2+ indicator dye (100 μM Fura-6F) in order not to overwhelm endogenous Ca2+ buffers. We first study voltage-clamped terminals, dialyzed with pipette solutions containing minimal amounts of Ca2+ buffers, to determine Ca2+ binding properties of endogenous fixed buffers as well as the mechanisms of Ca2+ clearance. Subsequently, we use pipette solutions including 500 μM EGTA in order to determine the Ca2+ binding kinetics of this chelator. We provide a formalism and parameters, which allow one to predict [Ca2+]i changes in calyx nerve terminals in response to a wide range of stimulus protocols. Unexpectedly, we find that the Ca2+-affinity of EGTA under the conditions of our measurements is substantially lower (KD = 543 ± 51 nM) than measured in vitro, mainly as a consequence of a higher then previously assumed dissociation rate constant (2.38 ± 0.20 s−1), which we need to postulate in order to model the measured presynaptic [Ca2+]i transients. This article is protected by copyright. All rights reserved

We employed first-principles calculations to investigate the lithiation mechanisms of functionalized graphene nanoribbons (GNRs) and to examine the effect of various functional groups on the electrochemical performance of graphene-based nanomaterials. In this work, we have extensively explored the Li storage behaviors of various types of functional groups located on the basal plane and those terminating the edge sites within different levels of lithiation and functionalization on GNRs. For functional groups terminating the edge sites, only ketone and its related derivatives (pyrone/quinone) can effectively enhance Li adsorption on GNRs, and the most favorable sites for Li adsorption turn out to be these edge-oxidized groups rather than the hollow sites on the basal plane. In addition, as the ketone-terminated GNRs were fully lithiated, the Li/O atomic ratio was found to be ∼1.0 and that for the ketone–ether pair (pyrone) was ∼0.5, indicating that these edge-oxidized groups can effectively enhance the Li capacity of GNRs as compared with that of graphite (Li1/6C). As regards the in-plane functional groups, the epoxy and hydroxyl groups were shown to have multiple Li uptakes on the basal plane and appeared to serve as the nucleation centers for Li clustering, thereby resulting in the great enhancement of the Li capacity of GNRs. Our calculations showed that the achievable Li/O atomic ratio was 4 for the epoxy group (Li4O pyramid cluster) and 3 for the hydroxyl group (Li3(OH) cluster), which suggests that these in-plane functional groups can be more effective in enhancing the Li storage capacity than those terminating the edge sites of graphene-based nanomaterials.

Here, a novel deep blue emitter SBABz4 for use in organic light-emitting diodes (OLED) is investigated. The molecular design of the emitter enables thermally activated delayed fluorescence (TADF), which we examine by temperature-dependent time-resolved electroluminescence (trEL) and photoluminescence (trPL). We show that the dihedral angle between donor and acceptor strongly affects the oscillator strength of the charge transfer state alongside the singlet–triplet gap. The angular dependence of the singlet–triplet gap is calculated by time-dependent density functional theory (TD-DFT). A gap of 15 meV is calculated for the relaxed ground state configuration of SBABz4 with a dihedral angle between the donor and acceptor moieties of 86°. Surprisingly, an experimentally obtained energy gap of 72±5 meV can only be explained by torsion angles in the range of 70°–75°. Molecular dynamics (MD) simulations showed that SBABz4 evaporated at high temperature acquires a distribution of torsion angles, which immediately leads to the experimentally obtained energy gap. Moreover, the emitter orientation anisotropy in a host matrix shows an 80% ratio of horizontally oriented dipoles, which is highly desirable for efficient light outcoupling. Understanding intramolecular donor-acceptor geometry in evaporated films is crucial for OLED applications, because it affects oscillator strength and TADF efficiency.

Nanoprobes such as single-walled carbon nanotubes (SWCNTs) are capable of label-free detection that benefits from intrinsic and photostable near-infrared fluorescence. Despite the growing number of SWCNT-based applications, uncertainty surrounding the nature of double-stranded DNA (dsDNA) immobilization on pristine SWCNTs has limited their use as optical sensors for probing DNA-protein interactions. To address this limitation, we study enzyme activity on unmodified dsDNA strands immobilized on pristine SWCNTs. Restriction enzyme activity on various dsDNA sequences was used to verify the retention of the dsDNA's native conformation on the nanotube surface and to quantitatively compare the degree of dsDNA accessibility. We report a 2.8-fold enhancement in initial enzyme activity in the presence of surfactants. Förster resonance electron transfer (FRET) analysis attributes this enhancement to increased dsDNA displacement from the SWCNT surface. Furthermore, the accessibility of native dsDNA was found to vary with DNA configuration and the spacing between the restriction site and the nanotube surface, with a minimum spacing of four base pairs (bp) from the anchoring site needed to preserve enzyme activity. Molecular dynamics (MD) simulations verify that the anchored dsDNA remains within the vicinity of the SWCNT, revealing an unprecedented bimodal displacement of the bp nearest to SWCNT surface. Together, these findings illustrate the successful immobilization of native dsDNA on pristine SWCNTs, offering a new near-infrared platform for exploring vital DNA processes.

Hole transport materials (HTMs) exhibiting suitable electronic properties, fast hole transport, high hydrophobicity and good oxygen resistance are critical for realizing perovskite solar cells (PSCs) that are stable and exhibit high-performance. Manipulating the length of alkyl chains is a widely adopted strategy that can fine tune the properties of organic materials in order to enhance their performance for various applications. Yet, a systematic exploration of the influence of chain length on those properties most relevant to highly performing HTMs in PSCs is lacking. Multiscale simulations, along with morphological analyses, uncover relationships between alkyl chain length and HTM properties that provide important insights for the optimization of future organic materials.

DNA has been extensively studied due to its versatility as a dispersant of SWCNTs. The specificity and binding affinity of DNA to various analytes has been shown to be strongly sequence dependent. As a result, through modifications of the nucleotide sequence, the DNA conformation on the SWCNT surface can be tailored to suit specific needs for techniques such as single-molecule detection, in vivo imaging, and chirality separation. To date, the majority of research has focused on the interaction between single-stranded DNA and SWCNT surface, with less focus on the nature of the interaction between double-stranded DNA (dsDNA) and SWCNTs. As a result, the exact interaction mechanism governing this type of complex remains strongly debated and largely unknown. In this study, we employ various biochemical methods to infer the conformation of dsDNA on the surface of SWCNTs. Our methods are based on imaging techniques for identifying DNA-modifying enzyme activity in the presence of dsDNA-SWCNT complexes. Our findings suggest that dsDNA can partially retain its native conformation on the SWCNT surface, and the degree of dsDNA accessibility is strongly sequence dependent. These findings offer new possibilities for SWCNT sensing applications that employ dsDNA, such as the optical detection of DNA-protein interactions.

Summary Short-term synaptic plasticity, the dynamic alteration of synaptic strength during high-frequency activity, is a fundamental characteristic of all synapses. At the calyx of Held, repetitive activity eventually results in short-term synaptic depression, which is in part due to the gradual exhaustion of releasable synaptic vesicles. This is counterbalanced by Ca 2+ -dependent vesicle replenishment, but the molecular mechanisms of this replenishment are largely unknown. We studied calyces of Held in knockin mice that express a Ca 2+ -Calmodulin insensitive Munc13-1 W464R variant of the synaptic vesicle priming protein Munc13-1. Calyces of these mice exhibit a slower rate of synaptic vesicle replenishment, aberrant short-term depression and reduced recovery from synaptic depression after high-frequency stimulation. Our data establish Munc13-1 as a major presynaptic target of Ca 2+ -Calmodulin signaling and show that the Ca 2+ -Calmodulin-Munc13-1 complex is a pivotal component of the molecular machinery that determines short-term synaptic plasticity characteristics.

BACKGROUND: Trunk muscle endurance training is used by most high school baseball or softball coaches. However, evidence demonstrating a relationship between trunk muscle endurance and batting performance is lacking. OBJECTIVE: This study aimed to establish a relationship between trunk muscle endurance and bat swing velocity in a high school baseball team. METHOD: Sixty-one high school (15–18 years old) baseball players, taken from the same team, with 6.5 ± 1.3 years of training experience, participated in the following tests: static trunk flexion/extension endurance tests, dynamic trunk flexion/extension endurance tests and a maximum bat swing velocity test. RESULTS:Bat swing velocity showed significant low-to-moderate negative correlations with static trunkflexor endurance (P = 0.001, r = �0.404), dynamic trunk flexor endurance (P = 0.016, r = �0.308) and the ratio of static flexor/extensor endurance (P = 0.021, r = �0.298). CONCLUSIONS: These findings support the concept that better trunk flexor endurance might not benefit batting performance. Trunk flexor endurance training should not be over-emphasized when the targeted training goal is to enhance bat swing velocity.

Neurotransmitter is released at synapses by fusion of synaptic vesicles with the plasma membrane. To sustain synaptic transmission, compensatory retrieval of membranes and vesicular proteins is essential. We combined capacitance measurements and pH-imaging via pH-sensitive vesicular protein marker (anti-synaptotagmin2-cypHer5E), and compared the retrieval kinetics of membranes and vesicular proteins at the calyx of Held synapse. Membrane and Syt2 were retrieved with a similar time course when slow endocytosis was elicited. When fast endocytosis was elicited, Syt2 was still retrieved together with the membrane, but endocytosed organelle re-acidification was slowed down, which provides strong evidence for two distinct endocytotic pathways. Strikingly, CaM inhibitors or the inhibition of the Ca2+-calmodulin-Munc13-1 signaling pathway only impaired the uptake of Syt2 while leaving membrane retrieval intact, indicating different recycling mechanisms for membranes and vesicle proteins. Our data identify a novel mechanism of stimulus- and Ca2+-dependent regulation of coordinated endocytosis of synaptic membranes and vesicle proteins.

The chromium–carbon–sulfur (Cr–C–S) deposits were electroplated from a trivalent Cr bath containing thiosalicylic acid. In the absence of thiosalicylic acid, the Cr–C deposit was amorphous and contained a significant amount of C. The Cr–C–S deposit plated in the bath containing thiosalicylic acid displayed a crystalline structure and was mainly composed of Cr, C, S, and oxygen. The presence of thiosalicylic acid in the bath apparently reduced the codeposition of C, which, in turn, enhanced the crystallinity of the Cr–C–S deposit. Furthermore, the codeposited S influenced the microstructure and properties of the deposits. The internal stress and population density of cracks of the deposit were reduced as more thiosalicylic acid was added in the trivalent Cr bath. Moreover, the corrosion potential was enhanced and the corrosion current density and the passivation current density were reduced with increasing bath thiosalicylic acid concentration. As a result, the crystalline, crack-free Cr–C–S deposit exhibited a better corrosion resistance than the amorphous Cr–C deposit.

Voltage-gated Ca2+channels (VGCCs) of the P/Q-type, which are expressed at a majority of mammalian nerve terminals, show two types of Ca2+-dependent feedback regulation—inactivation (CDI) and facilitation (CDF). Because of the nonlinear relationship between Ca2+influx and transmitter release, CDI and CDF are powerful regulators of synaptic strength. To what extent VGCCs inactivate or facilitate during spike trains depends on the dynamics of free Ca2+([Ca2+]i) and the Ca2+sensitivity of CDI and CDF, which has not been determined in nerve terminals. In this report, we took advantage of the large size of a rat auditory glutamatergic synapse—the calyx of Held—and combined voltage-clamp recordings of presynaptic Ca2+currents (ICa(V)) with UV-light flash-induced Ca2+uncaging and presynaptic Ca2+imaging to study the Ca2+requirements for CDI and CDF.We find that nearly half of the presynaptic VGCCs inactivate during 100 ms voltage steps and require several seconds to recover. This inactivation is caused neither by depletion of Ca2+ions from the synaptic cleft nor by metabotropic feedback inhibition, because it is resistant to blockade of metabotropic and ionotropic glutamate receptors. Facilitation ofICa(V)induced by repetitive depolarizations or preconditioning voltage steps decays within tens of milliseconds. Since Ca2+buffers only weakly affect CDI and CDF, we conclude that the Ca2+sensors are closely associated with the channel. CDI and CDF can be induced by intracellular photo release of Ca2+resulting in [Ca2+]ielevations in the low micromolar range, implying a surprisingly high affinity of the Ca2+sensors.

The functional properties of mammalian presynaptic nerve endings remain elusive since most terminals of the central nervous system are not accessible to direct electrophysiological recordings. In this study, direct recordings were performed for the first time at endbulb of Held terminals to characterize passive membrane properties, voltage-gated Ca(2+) channels (VGCCs) and Ca(2+)-dependent exocytosis. Endbulb of Held terminals arise from endings of auditory nerve fibres contacting spherical bushy cells (SBCs) in the anterior ventral cochlear nucleus (AVCN). These terminals had a high mean input resistance (1.1 G) and a small mean capacitance (4.3 pF). Presynaptic VGCCs were predominantly of the P/Q type (86%) and expressed at a high density with an estimated average number of 6400 channels per terminal. Presynaptic Ca(2+) currents (I(Ca(V))) activated and deactivated rapidly. Simulations of action potential (AP)-driven gating of VGCCs suggests that endbulb APs trigger brief Ca(2+) influx with a mean half-width of 240 μs and a peak amplitude of 0.45 nA which results from the opening of approximately 2600 channels. Unlike Ca(2+) currents at the calyx of Held, I(Ca(V)) of endbulb terminals showed no inactivation during trains of AP-like presynaptic depolarizations. Endbulb terminals are endowed with a large readily releasable vesicle pool (1064 vesicles) of which only a small fraction (

Recent progress in embryonic stem cell (ESC) and induced pluripotent stem cell (iPSC) research led to high-purity preparations of human cardiomyocytes (CMs) differentiated from these two sources-suitable for tissue regeneration, in vitro models of disease, and cardiac safety pharmacology screening. We performed a detailed characterization of the effects of nifedipine, cisapride, and tetrodotoxin (TTX) on Cor.4U(®) human iPSC-CM, using automated whole-cell patch-clamp recordings with the CytoPatch(™) 2 equipment, within a complex assay combining multiple voltage-clamp and current-clamp protocols in a well-defined sequence, and quantitative analysis of several action potential (AP) parameters. We retrieved three electrical phenotypes based on AP shape: ventricular, atrial/nodal, and S-type (with ventricular-like depolarization and lack of plateau). To suppress spontaneous firing, present in many cells, we injected continuously faint hyperpolarizing currents of -10 or -20 pA. We defined quality criteria (both seal and membrane resistance over 1 GΩ), and focused our study on cells with ventricular-like AP. Nifedipine induced marked decreases in AP duration (APD): APD90 (49.8% and 40.8% of control values at 1 and 10 μM, respectively), APD50 (16.1% and 12%); cisapride 0.1 μM increased APD90 to 176.2%; and tetrodotoxin 10 μM decreased maximum slope of phase to 33.3% of control, peak depolarization potential to 76.3% of control, and shortened APD90 on average to 80.4%. These results prove feasibility of automated voltage- and current-clamp recordings on human iPSC-CM and their potential use for in-depth drug evaluation and proarrhythmic liability assessment, as well as for diagnosis and pharmacology tests for cardiac channelopathy patients.

Significantly more Ca(2+) influx is required for eliciting release of neurotransmitter during whole cell patch clamp recording in the Calyx of Held, when gluconate with 3 mm free ATP is used as pipette filling solution, as compared to a methanesulfonate-based solution with excess Mg(2+). This reduction in efficiency of Ca(2+) in eliciting release is due to low-affinity Ca(2+) binding of both gluconate and ATP(2-) anions. To study these effects we developed a simple fluorimeteric titration procedure, which reports the dissociation constant, KD, of a given Ca(2+) indicator dye, multiplied by 1 plus the sum of Ca(2+) binding ratios of any anions, which act as low-affinity Ca(2+) ligands. For solutions without Ca(2+) binding anions we find KD values for Fura2FF ranging from 11.5 ± 1.7 to 15.6 ± 7.47 μm depending on the dominant anion used. For Fura6F and KCl-based solutions we find KD = 17.8 ± 1.3 μm. For solutions with gluconate as the main anion and for solutions that contain nucleotides, such as ATP and GTP, we find much higher values for the product. Assuming that the KD of the indicator dye is equal to that of KCl-based solutions we calculate the summed Ca(2+) binding ratios and find a value of 3.55 for a solution containing 100 mm potassium gluconate and 4 mm ATP. Gluconate contributes a value of 1.75 to this number, while the contribution of ATP depends strongly on the presence of Mg(2+) and varies from 0.8 (with excess Mg(2+)) to 13.8 (in the presence of 3 mm free ATP). Methanesulfonate has negligible Ca(2+) binding capacity. These results explain the reduced efficiency of Ca(2+) influx in the presence of gluconate or nucleotides, as these anions are expected to intercept Ca(2+) ions at short distance.

Calyx and endbulb synapses of the mammalian auditory brainstem are specialized in transmitting spike activity fast, sustained and temporally precise. To accomplish this task, they make use of unusually large presynaptic elements which form axosomatic contacts with their postsynaptic target neurons. The large size of the calyceal terminals represents a major experimental advantage and has enabled electrophysiologists to study the functional properties of Ca2+ channels in presynaptic CNS terminals in great detail, with high time resolution and unprecedented precision. Calyx and endbulb terminals express several thousands of Ca2+ channels with rapid kinetics which ensure fast and efficient gating of Ca2+ influx during brief action potentials. When repetitively activated, presynaptic Ca2+ influx is modulated in a frequency-dependent manner and this Ca2+ current modulation contributes significantly to short-term plasticity at these synapses. During short high-frequency bursts, Ca2+ influx is facilitated whereas tetanic activity or low-frequency firing leads to an accumulation of Ca2+ channel inactivation. When the calyx synapses mature, the coupling between docked transmitter vesicles and Ca2+ channels becomes tighter to compensate for the shortening of the presynaptic action potential duration. Many of the G protein-dependent pathways of Ca2+ channel regulation that are potent in immature synapses are weakened during postnatal development.