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Abstract Hofmann coordination polymers (CPs) that couple the well-studied spin transition of the FeII central ion with electron-responsive ligands provide an innovative strategy toward multifunctional metal-organic frameworks (MOFs). Here, we developed a 2D planar network consisting of metal-cyanide-metal sheets in an unusual coordination mode, brought about by infinitely π-stacked redox-active bipyridinium derivatives as axial ligands. The obtained family of materials show vivid thermochromism attributed to electron transfer and/or electronic spin state change processes that can occur either independently or concomitantly. Importantly, the redox activity of the ligands within the structure leads to the quasi-reversible electrochemical reduction reaction on a spin-crossover complex at solid state. These observations have been confirmed via temperature-dependent single-crystal X-ray diffraction, magnetic measurements, Mössbauer, EPR, optical and vibrational spectroscopies as well as quantum chemical calculations.

We used stereolithography to print polymer nanocomposite samples of stimuli-responsive spin crossover materials in the commercial photo-curable printing resins DS3000 and PEGDA-250. The thermomechanical analysis of the SLA-printed objects revealed not only the expected reinforcement of the polymer resins by the introduction of the stiffer SCO particles, but also a significant mechanical damping, as well as a sizeable linear strain around the spin transition temperatures. For the highest accessible loads (ca. 13–15 vol.%) we measured transformation strains in the range of 1.2–1.5%, giving rise to peaks in the coefficient of thermal expansion as high as 10−3 °C−1, which was exploited in 3D printed bilayer actuators to produce bending movement. The results pave the way for integrating these advanced stimuli-responsive composites into mechanical actuators and 4D printing applications.

Abstract Understanding phase transformation processes at the nanoscale is an important step for the integration of phase change materials into functional nanodevices. Here, a numerical method to assess surface energy and surface stress contributions to finite size effects in spin crossover nanomaterials is proposed. Starting from their formal definitions, molecular dynamic simulations combined with continuum mechanics and thermodynamic considerations on model thin films are performed. The surface energy values extracted from the simulations are 71 and 79 mJ m−2 for the high spin (HS) and low spin (LS) states, respectively. In the limit of a weak lattice parameter misfit, the calculated isotropic stresses of a HS/LS interface are 94 and 45 mJ m−2 for the LS and HS states, respectively. From these results, a ≈10 K downshift of the spin transition temperature is predicted with the size reduction. Whereas surface energy favors systematically the HS state, it is not the case for the interface stress. Indeed, it is demonstrated that the anisotropy of mechanical stresses can lead to the stabilization of the LS state. These results confirm the possible control of the phase stability in these smart nanomaterials through interface engineering.

Summary: Spin crossover (SCO) complexes, through their reversible spin transition under external stimuli, can work as switchable memory materials. Here, we present a protocol for the synthesis and characterization of a specific polyanionic iron SCO complex and its diluted systems. We describe steps for its synthesis and the determination of crystallographic structure of the SCO complex in diluted systems. We then detail a range of spectroscopic and magnetic techniques employed to monitor the spin state of the SCO complex in both diluted solid- and liquid-state systems.For complete details on the use and execution of this protocol, please refer to Galán-Mascaros et al.1 : Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.

Molecular spin‐crossover (SCO) complexes are phase‐change materials that develop large spontaneous strains across the thermally induced phase transition, which can be advantageously used in designing soft actuators. Herein, a bilayer bending cantilever, made of thermoplastic polyurethane (TPU) with embedded [Fe(NH2trz)3](SO4) SCO particles (25 wt%), is presented. The proposed actuator is fabricated by blade casting an SCO@TPU layer on a conducting Ag@TPU film to convert electrothermal input into mechanical response. Experiments are conducted to characterize the curvature of bilayer beams, which is then further analyzed using the Euler–Bernoulli beam theory. The beam curvature change, free transformation strain, and effective work density associated with the SCO are 0.11 mm−1, 1.6%, and 1.25 mJ cm−3, respectively. Further, the open‐ and closed‐loop response of the actuator is investigated using a custom‐built setup. The open‐loop identification suggests that the actuator gain increases monotonously when the control current increases. This natural adaptive character can explain the drastically diminished response time in closed‐loop proportional–integral–derivative control experiments (2–3 s). Finally, tracking experiments are carried out to evaluate the robustness of the actuator with and without payloads. The results for 30 240 endurance cycles reveal a mean positioning error of 0.8%.

Patch clamp recording of neurons is slow and labor-intensive. Here the authors present a method for automated deep learning driven label-free image guided patch clamp physiology to perform measurements on hundreds of human and rodent neurons.

Developing novel thermometry techniques for nanoscale temperature measurements are vital for realizing efficient thermal management of nanoscale devices. Here, the authors report thermally stable spin-crossover material-based nanothermometers for high-resolution surface temperature mapping.

Summation of ionotropic receptor-mediated responses is critical in neuronal computation by shaping input-output characteristics of neurons. However, arithmetics of summation for metabotropic signals are not known. We characterized the combined ionotropic and metabotropic output of neocortical neurogliaform cells (NGFCs) using electrophysiological and anatomical methods in the rat cerebral cortex. These experiments revealed that GABA receptors are activated outside release sites and confirmed coactivation of putative NGFCs in superficial cortical layers in vivo. Triple recordings from presynaptic NGFCs converging to a postsynaptic neuron revealed sublinear summation of ionotropic GABAA responses and linear summation of metabotropic GABAB responses. Based on a model combining properties of volume transmission and distributions of all NGFC axon terminals, we predict that in 83% of cases one or two NGFCs can provide input to a point in the neuropil. We suggest that interactions of metabotropic GABAergic responses remain linear even if most superficial layer interneurons specialized to recruit GABAB receptors are simultaneously active.

Az embereknek, mielőtt megegyeznek egy alkuban, először szükségszerűen rendezniük kell az árukért cserébe adott pénz értékét vagy árát. És ha ez körülnyírt vagy rossz pénzben történik, akkor annak megfelelően állapítják meg az áruk árát: ami szerintem az áremelkedés egyik fő oka volt, nemcsak az árukereskedelemben, de az élelmiszerek és a közemberek minden más létfenntartási szükséglete kapcsán, a legnagyobb sérelmükre. Hogy mindenki, aki a pénzünk emelése után jut a változtatás előtt megkötött szerződései alapján pénzhez, húsz százalékot kell, hogy veszítsen mindenen, amit azután megvesz, az Mr. Lowndes saját terve alapján is bemutatható.

Mélyen tisztelt Sir John Sommers lordkancellárnak, az angol állami nagypecsét őrzőjének, Őfelsége egyik legtiszteletreméltóbb tanácsosának. Uram, Az Uram számára itt bemutatott tanulmányok tartalmukban azonosak azzal, amelyet Uramtól, az excellenciáitól és a bíró uraktól kapott parancsoknak engedelmeskedve bocsátottam rendelkezésére, valamint egy másikkal, amit azokra a kérdésekre válaszul írtam, amit Uram a pénzünkkel kapcsolatban szíveskedett feltenni. Az elismerés, amelyet Uram akkor szíveskedett nekik adni, arra bátorított, hogy felülvizsgáljam és rendbe rakjam őket. Mégpedig a céljuknak megfelelőbb módon, ami azt igényli, hogy nyomtatásban nyilatkozzak meg most ebben a kérdésben. És lehet-e bármi ilyen természetű dolgot közönyösen fogadni ebben a korban; az a figyelem, amelyre méltatta őket Uram, akinek hatalmas és tiszta ítélete – általános beleegyezéssel és ünnepléssel – a helyes és helytelen elismert mércéje köztünk, arra a reményre ad jogot, hogy különösebb ellenszenv nélkül elfogadtatást nyernek majd a világban.

Inhibitory autapses are self-innervating synaptic connections in GABAergic interneurons in the brain. Autapses in neocortical layers have not been systematically investigated, and their function in different mammalian species and specific interneuron types is poorly known. We investigated GABAergic parvalbumin-expressing basket cells (pvBCs) in layer 2/3 (L2/3) in human neocortical tissue resected in deep-brain surgery, and in mice as control. Most pvBCs showed robust GABAAR-mediated self-innervation in both species, but autapses were rare in nonfast-spiking GABAergic interneurons. Light- and electron microscopy analyses revealed pvBC axons innervating their own soma and proximal dendrites. GABAergic self-inhibition conductance was similar in human and mouse pvBCs and comparable to that of synapses from pvBCs to other L2/3 neurons. Autaptic conductance prolonged somatic inhibition in pvBCs after a spike and inhibited repetitive firing. Perisomatic autaptic inhibition is common in both human and mouse pvBCs of supragranular neocortex, where they efficiently control discharge of the pvBCs.

We used a spray-coating process to cover silicon microcantilevers with ca. 33 wt% [Fe(Htrz)2(trz)](BF4)@P(VDF70-TrFE30) nanocomposite thin films of 1500 nm thickness. The bilayer cantilevers were then used to investigate the thermomechanical properties of the composites through a combined static and dynamic flexural analysis. The out-of-plane flexural resonance frequencies were used to assess the Young’s modulus of the spray-coated films (3.2 GPa). Then, the quasi-static flexural bending data allowed us to extract the actuation strain (1.3%) and an actuation stress (7.7 MPa) associated with the spin transition in the composite.

The aqueducts built by the ancient Romans are among the most impressive evidence of their engineering skills. The water inside the aqueducts was transported for kilometers, exploiting only the slight but constant differences in altitude throughout the route. To keep the differences in height constant, the aqueducts could proceed underground or aboveground on well-known arched structures that supported lead, ceramic or stone pipes. In order to reconstruct the characteristics of these structures, it is necessary to carry out an accurate survey of the orthometric heights, and therefore the most suitable technology is geometric levelling. In this case, however, it is not applicable, and therefore here we propose an alternative methodology. The final goal of this work was to estimate the flow of some sectors of these aqueducts preserved in the area south of the city of Rome. This has two main purposes: The first is to reconstruct the flow rate of these aqueducts for historical studies; the second is to check how much the orthometric heights have changed over the centuries, in order to reconstruct the movements from a geophysical and geodynamic point of view. The latter analysis will be developed in a following phase of this research. For this purpose, a high-precision geomatic survey was carried out in the area under study, partly retracing a survey already carried out in 1917 whose purpose and methodologies are not known. The area has been affected by a gradual subsidence over centuries, including since 1917. The observed sections of the aqueducts showed average inclinations, slightly lower than the 2 per thousand that is reported in the literature for similar aqueducts. The measurements carried out allowed the flow rate of the two specific aqueducts to be estimated more accurately, both as they were originally and in the presence of deposits that have accumulated during the years of use of the aqueducts. The reconstruction of the initial geometry will later be used as a reference to estimate how much the geodynamic deformations of the area have deformed the aqueducts themselves.

Size reduction effects on the lattice dynamics of spin crossover (SCO) thin films have been investigated through molecular dynamics (MD) simulations of the density of vibrational states. The proposed simple model structure and reduced force field allows us to obtain good orders of magnitude of the sound velocity in both spin states and takes into account the contribution of free surfaces in the vibrational properties of very thin films (below a thickness of 12 nm). The slab method issue from the field of surface physico-chemistry has been employed to extract surface thermodynamic quantities. In combination with the related slab-adapted method, the slab approach provides a powerful numerical tool to separate surface contributions from finite-size effects. Due to the relatively low stiffness of SCO materials, the lattice dynamics seems to be governed by surface instead of confinement effects. The size evolution of thermodynamic quantities is successfully reproduced, especially the increase of the vibrational entropy with the size reduction, in good agreement with experimental observations.

We studied the spin-state dependence of the electrical conductivity of two nanocrystalline powder samples of the spin crossover complex [Fe(pyrazine){Au(CN)2}2]. By applying an external pressure (up to 3 kbar), we were able to tune the charge transport properties of the material from a more conductive low spin state to a crossover point toward a more conductive high spin state. We rationalize these results by taking into account the spin-state dependence of the activation parameters of the conductivity.

This review reports on the recent progress in the synthesis, modelling and application of hybrid spin-crossover materials, including core–shell nanoparticles and multilayer thin films or nanopatterns. These systems combine, often in synergy, different physical properties (optical, magnetic, mechanical and electrical) of their constituents with the switching properties of spin-crossover complexes, providing access to materials with unprecedented capabilities.

We report on the vacuum thermal deposition of bilayer thin films of the luminescent complex Ir(ppy)3, tris[2-phenylpyridinato-C2,N]iridium(III), and the spin crossover complex [Fe(HB(tz)3)2], bis[hydrotris(1,2,4-triazol-1-yl)borate]iron(II). Switching the spin state of iron ions from the low spin to the high spin state around 337 K leads to a reversible jump of the luminescence intensity, while the spectrum shape and the luminescence lifetime remain unchanged. The luminescence modulation occurs due to the different UV light absorption properties of the iron complex in the two spin states and its magnitude can therefore be precisely adjusted by varying the film thickness. These multilayer luminescence switches hold potential for micro- and nanoscale thermal sensing and imaging applications.

Whole-cell patch-clamp recording enables detection of electrophysiological signals from single neurons as well as harvesting of perisomatic RNA through the patch pipette for subsequent gene expression analysis. Amplification and profiling of RNA with traditional quantitative real-time PCR (qRT-PCR) do not provide exact quantitation due to experimental variation caused by the limited amount of nucleic acid in a single cell. Here we describe a protocol for quantifying mRNA or miRNA expression in individual neurons after patch-clamp recording using high-density nanocapillary digital PCR (dPCR). Expression of a known cell-type dependent marker gene (gabrd), as well as oxidative-stress related induction of hspb1 and hmox1 expression, was quantified in individual neurogliaform and pyramidal cells, respectively. The miRNA mir-132, which plays a role in neurodevelopment, was found to be equally expressed in three different types of neurons. The accuracy and sensitivity of this method were further validated using synthetic spike-in templates and by detecting genes with very low levels of expression.

Classic theories link cognitive abilities to synaptic properties and human-specific biophysical features of synapses might contribute to the unparalleled performance of the human cerebral cortex. Paired recordings and multiple probability fluctuation analysis revealed similar quantal sizes, but 4-times more functional release sites in human pyramidal cell to fast-spiking interneuron connections compared to rats. These connections were mediated on average by three synaptic contacts in both species. Each presynaptic active zone (AZ) contains 6.2 release sites in human, but only 1.6 in rats. Electron microscopy (EM) and EM tomography showed that an AZ harbors 4 docked vesicles in human, but only a single one in rats. Consequently, a Katz’s functional release site occupies ~0.012 μm2 in the human presynaptic AZ and ~0.025 μm2 in the rat. Our results reveal a robust difference in the biophysical properties of a well-defined synaptic connection of the cortical microcircuit of human and rodents.

SI: Originalnih listov sistemskih kart tretje vojaške izmere avstro-ogrske monarhije zaradi trapeznega formata ne moremo stično mozaičiti v ravnini. Če želimo izdelati digitalni mozaik listov, jih moramo transformirati, in če jih želimo uporabiti hkrati z drugimi podatki v GIS-u, jih moramo tudi georeferencirati. Namesto originalnih projekcij, ki so na vsakem listu drugačne, smo definirali niz sinusoidnih projekcij, in sicer enotne projekcije za vsak posamezen stolpec listov. Sinusoidna projekcija omogoča primeren približek za prvotne trapezaste oblike in je primerna glede na dejansko velikost listov. Vsak list je bil nato rektificiran (izravnan) v ustrezno projekcijo in nato preprojiciran v splošno stožčno projekcijo, definirano za končen mozaik. Po izvedbi vseh operacij se digitalna vsebina listov medsebojno dovolj dobro ujema za izdelavo georeferenciranega mozaika. Lokacijski parametri geodetskega datuma, uporabljeni za transformacijo v današnji koordinatni sistem, so naslednji: dX = +600 m, dY = +205 m, dZ = +437 m. Ti podatki omogočajo točno in natančno ujemanje s fundamentalno točko na Hermannskoglu. Zara i neenotne izravnave (neuporabe enotnega datuma) celotnega sistema geodetskih točk so v modernem usklajenem modelu posamezna območja in torej tudi sistemske karte monarhije lokalno-sistematično uravnani z zamikom do 220 metrov. EN: The original map sheets of the third military survey of the Austro-Hungarian Empire cannot be mosaicked in their original, printed form as their format is uneven and trapezoidal. To make a digitized raster mosaic of individual sheets, they should all be transformed, as well as georeferenced for applications in GIS. Instead of the original projections, which vary from sheet to sheet, a series of sinusoid projections was defined, one unique projection for each sheet column. The sinusoid projection provides an appropriate approximation of the original trapezoid forms and size of the sheets. Each sheet was rectified in the respective projection MOZAIÈENJE LISTOV KART MERILA 1 : 75.000 TRETJE VOJAŠKE IZMERE AVSTRO-OGRSKE and then reprojected to a general conic projection, defined for the final mosaic. After all the operations were carried out, the transformed digital content of the sheets adequately fits together to make a georeferenced mosaic. The location parameters of the geodetic date used for transformation to modern projection systems are the following: dX = +600 m, dY = +205 m, dZ = +437 m. These figures give exact fit at the Hermannskogel reference point. Because of the not unified geodetic adjustment of the original base point system, using one unified date causes a maximum error of 220 m throughout the whole territory of the Empire and the adjacent area on the maps.

Synaptic interactions between neurons of the human cerebral cortex were not directly studied to date. We recorded the first dataset, to our knowledge, on the synaptic effect of identified human pyramidal cells on various types of postsynaptic neurons and reveal complex events triggered by individual action potentials in the human neocortical network. Brain slices were prepared from nonpathological samples of cortex that had to be removed for the surgical treatment of brain areas beneath association cortices of 58 patients aged 18 to 73 y. Simultaneous triple and quadruple whole-cell patch clamp recordings were performed testing mono- and polysynaptic potentials in target neurons following a single action potential fired by layer 2/3 pyramidal cells, and the temporal structure of events and underlying mechanisms were analyzed. In addition to monosynaptic postsynaptic potentials, individual action potentials in presynaptic pyramidal cells initiated long-lasting (37 +/- 17 ms) sequences of events in the network lasting an order of magnitude longer than detected previously in other species. These event series were composed of specifically alternating glutamatergic and GABAergic postsynaptic potentials and required selective spike-to-spike coupling from pyramidal cells to GABAergic interneurons producing concomitant inhibitory as well as excitatory feed-forward action of GABA. Single action potentials of human neurons are sufficient to recruit Hebbian-like neuronal assemblies that are proposed to participate in cognitive processes.