Adjacent Units Research Articles

Interplay between π-Conjugation and Exchange Magnetism in One-Dimensional Porphyrinoid Polymers.

The synthesis of novel polymeric materials with porphyrinoid compounds as key components of the repeating units attracts widespread interest from several scientific fields in view of their extraordinary variety of functional properties with potential applications in a wide range of highly significant technologies. The vast majority of such polymers present a closed-shell ground state, and, only recently, as the result of improved synthetic strategies, the engineering of open-shell porphyrinoid polymers with spin delocalization along the conjugation length has been achieved. Here, we present a combined strategy toward the fabrication of one-dimensional porphyrinoid-based polymers homocoupled via surface-catalyzed [3 + 3] cycloaromatization of isopropyl substituents on Au(111). Scanning tunneling microscopy and noncontact atomic force microscopy describe the thermal-activated intra- and intermolecular oxidative ring closure reactions as well as the controlled tip-induced hydrogen dissociation from the porphyrinoid units. In addition, scanning tunneling spectroscopy measurements, complemented by computational investigations, reveal the open-shell character, that is, the antiferromagnetic singlet ground state (S = 0) of the formed polymers, characterized by singlet–triplet inelastic excitations observed between spins of adjacent porphyrinoid units. Our approach sheds light on the crucial relevance of the π-conjugation in the correlations between spins, while expanding the on-surface synthesis toolbox and opening avenues toward the synthesis of innovative functional nanomaterials with prospects in carbon-based spintronics.

Formation age of lunar Lalande crater and its implications for the source region of the KREEP-rich meteorite Sayh al Uhaymir 169

As the most KREEP-rich lunar sample, the Sayh al Uhaymir (SaU) 169 meteorite would provide more valuable information concerning the KREEP and early lunar evolution of the Moon if its source regions can be pinpointed. Previous studies proposed Lalande crater as the source region that corresponds to the impact event of ~2.8 Ga recorded in SaU 169, whereas this linkage is highly dependent on the age determination of the potential source crater. By counting craters superposed on the ejecta blankets of Lalande and modelling the burial process of these superposed craters by Lalande's ejecta, we find that the crater statistics around Lalande are heavily influenced by the existing of pre-Lalande craters larger than ~170 m in diameter, which could lead to a largely overestimated age of Lalande crater. After taking this influence into consideration, we obtain that Lalande crater is a Copernican crater with a formation age of 410 ± 20 Ma, and the adjacent mare basalts unit has an Imbrian age of 3.8−0.06+0.04 Ga. The formation age of Lalande crater is inconsistent with any of the radio-isotopic ages recorded in SaU 169, indicating that Lalande crater is unlikely to be the source region of this lunar meteorite.

Physical property studies to elucidate the source of seismic reflectivity within the ICDP DSeis seismogenic zone: Klerksdorp goldfield, South Africa

Petrophysical properties of cylindrical core specimens from three boreholes from the International Continental Scientific Drilling Program, the DSeis project, measured at ambient pressure and room temperature conditions in various laboratories are presented and compared with downhole petrophysical data (sonic and density). The measured properties are from sixty-six rock specimens constituting metasediments, metabasalts and intrusives. Seismic velocities were measured using 0.5 MHz P- and S-wave transducers. To investigate the source of seismic reflectivity observed on the 2D legacy seismic data, we computed synthetic seismograms for adjacent rock units using downhole petrophysical data and compared them with seismic reflections from the reflection seismic profile. The experimental measurements show that the metasediments exhibit lower bulk densities and seismic velocities than the metabasalts and intrusive specimens. The porosity was found to be less than 2% for all the samples. No clear trends emerge when the Poisson's ratio is plotted against the P-wave velocities and porosities of the samples. A positive relationship is observed between the bulk modulus and P-wave velocities of the rock samples. The highest calculated reflection coefficients (RC) are associated with the metasediment-intrusive interfaces in all three boreholes. The intrusive-metabasalt and the metasediment-metabasalt interfaces exhibit low RC. Synthetic seismograms reveal strong reflections that coincide with high RC calculated using the bulk density and velocity data. The synthetic seismograms also revealed additional strong reflections that were not identified using the reflection coefficients calculated from the rock specimens, due to core loss in some lithological units. Successful correlations are carried out between the synthetic seismic data and the real seismic data, enabling us to correlate the stratigraphic sequence drilled in the boreholes to the seismic reflections observed on the legacy 2D reflection seismic data.

Rigid Bay-Conjugated Perylene Bisimide Rotors: Solvent-Induced Excited-State Symmetry Breaking and Resonance-Enhanced Two-Photon Absorption

Intramolecular charge transfer and excited-state symmetry breaking have a significant effect on the nonlinear optical properties of multipolar chromophores. Rigid and nonplanar perylene bisimide derivatives (PBIs) functionalized at bay positions were comparatively and comprehensively investigated. In apolar solvents, two quadrupolar molecular rotors showed an obvious decrease of the A0-0/A0-1 ratios, suggesting strong exciton coupling with the adjacent PBI units initiated by the π-π stacking. The vanishment of the preferable dimer emission in polar solvents supported the plausible phenomena of excited-state symmetry breaking, thanks to the facile rotation around the rigid linkers. Comparative femtosecond transition absorption studies confirmed their notable differences in relaxation dynamics and the generation of radical anions (PBI•-) and cations (PBI•+). The maxima two-photon absorption (2PA) wavelengths obtained for the molecular rotors were slightly red-shifted to 670 nm with intrinsic resonance-enhanced characteristics, reflecting the synergistic effect of functional positions and molecular architectures. Meanwhile, the obvious increase of significant 2PA cross-section values in polar solvents illustrated the stabilization of the symmetry-broken dipolar states. Further femtosecond Z-scan also manifested the contribution of excited-state dynamics on the nonlinear optical properties of multipolar chromophores.

Locating skarns with magnetic survey data, Geyer, Erzgebirge: optimizing data acquisition procedures

ABSTRACTMagnetic data can be acquired from a number of different platforms (e.g., ground, drone, helicopter) using a variety of sensors (e.g., caesium vapour‐type optically pumped magnetometers, fluxgate, superconducting quantum interference devices) with different flight line configurations. To detect a magnetic anomaly associated with a mineral commodity that is not exposed but is thought to be associated with the anomalous magnetic mineral content, it is necessary to optimize the survey parameters through a complete data integration process. Prior petrophysical measurements provide insight into the physical contrast that might be expected between adjacent lithologic units and between the ore zone and the encompassing lithology. Oriented rock samples provide access to magnetic remanence data through palaeomagnetic laboratory measurements. Knowing the typical morphology of the ore zone one can compute a forward model of the expected anomalous response and determine which combination of survey parameters provides the highest probability of detecting the commodity being sought. In this study, we analyse magnetic patterns associated with thin dipping skarn bodies from the Geyer mining district in Erzgebirge, Germany. Petrophysical measurements indicate that the skarns are more magnetic than the surrounding host rock. Partially oriented samples from a bore core record a Variscan age metamorphic remanence. Forward modelling indicates that clusters of skarn bodies are required to produce a reliably detectable magnetic signal. Ground, or low elevation drone surveys are needed to detect these anomalies with standard scalar‐type optically pumped magnetometer or fluxgate magnetic surveys. The enhanced spatial resolution and long‐wavelength rejection of a superconducting quantum interference device based full‐tensor magnetic gradiometer provide an improvement over optically pumped magnetometers for an aircraft‐based survey platform.

Neutrophil-Biomimetic "Nanobuffer" for Remodeling the Microenvironment in the Infarct Core and Protecting Neurons in the Penumbra via Neutralization of Detrimental Factors to Treat Ischemic Stroke.

High level of detrimental factors including reactive oxygen species (ROS) and inflammatory cytokines accumulated in the infarct core and their erosion to salvageable penumbra are key pathological cascades of ischemia-reperfusion injury in stroke. Few neuroprotectants can remodel the hostile microenvironment of the infarct core for the failure to interfere with dead or biofunctionally inactive dying cells. Even ischemia-reperfusion injury is temporarily attenuated in the penumbra by medications; insults of detrimental factors from the core still erode the penumbra continuously along with drug metabolism and clearance. Herein, a strategy named "nanobuffer" is proposed to neutralize detrimental factors and buffer destructive erosion to the penumbra. Inspired by neutrophils' tropism to the infarct core and affinity to inflammatory cytokines, poly(lactic-co-glycolic acid) (PLGA) nanoparticles are coated with neutrophil membrane to target the infarct core and absorb inflammatory cytokines; α-lipoic acid is decorated on the surface and cannabidiol is loaded for ROS scavenging and neuroprotection, respectively, to construct the basic unit of the nanobuffer. Such a nanobuffer exerts a comprehensive effect on the infarct area via detrimental factor neutralization and cannabidiol-induced neuroprotection. Besides, the nanobuffer can possibly be enhanced by dynamic ROP (ring-opening-polymerization)-induced membrane cross-fusion among closely adjacent units in vivo. Systematic evaluations show significant decrease of detrimental factors in the core and the penumbra, reduced infarct volume, and improved neurological recovery compared to the untreated group of stroke rats.

Estimating the pollutant loss rate based on the concentration process and landscape unit interactions: a case study of the Dianchi Lake Basin, Yunnan Province, China

The landscape analysis model establishes a quantitative relationship between landscape patterns and pollution processes. The spatial heterogeneity within and between landscapes affects the pollutant transmission process and originates from the superposition effect of terrestrial geographical and morphological characteristics. This study aimed to develop a new method to estimate the pollutant loss rate. From the perspective of the flow process of pollutants entering a water body, the interaction between each landscape unit and adjacent unit during pollutant migration was simulated along the pollutant migration flow path. The role of pollutants affected by external forces in the process of migration could be divided into "promoting" and "hindering." Four indices were proposed to simulate the pollutant loads entering the lake. The linear coefficients between the load of the pollutants chemical oxygen demand (CODCr), ammoniacal nitrogen (NH3-N), total nitrogen (TN), and total phosphorus (TP) entering the lake and the pollutant load emission weighted by the upstream and downstream confluence ratio index were 0.930, 0.835, 0.925, and 0.795, respectively, and the non-linear variance explanation coefficients were 87.70%, 87.50%, 87.60%, and 84.70%, respectively. When the surface resistance was integrated into the index as a parameter, the linear and nonlinear correlation coefficients were significantly improved. The linear coefficients were 0.952, 0.897, 0.919, and 0.939, respectively, and the non-linear variance explanations were 99.00%, 97.30%, 95.10%, and 97.30%, respectively. The spatial distribution of landscape surface resistance reflects the spatial movement trend of pollutants from different sources. The indices characterizing the promoting and hindering effects could be integrated to calculate the loss rate of pollutant load entering the lake from landscape units at different locations in the basin space.

Pounding performance between a seismic-isolated long-span girder bridge and its approaches

For girder bridges located in regions with a high seismic hazard level, seismic isolation bearings are usually implemented to suppress the seismic inertial force transmitted from the superstructure to substructures, protecting the pier columns and foundations. However, whether potential pounding might happen for these seismic-isolated girder bridges between adjacent units are scarcely considered, especially for those with long spans where the wave passage effect is of great significance. This paper develops a finite element model for a typical hybrid truss-girder bridge, based on which the influence of seismic isolation bearings and wave passage effect on pounding is carefully investigated considering both near-fault and far-field motions. The results show that for this type of long-span girder bridges, pounding may happen even the adjacent bridge units are designed with similar vibration periods, especially when near-fault motions and wave passage effect are considered. Under non-uniform excitations with different apparent wave velocities, the employment of isolation bearings can reduce the relative displacement at expansion joints and thus improve the performance against pounding; however, the occurrence of pounding and damage of expansion joints cannot be fully avoided. Further, motions with lower apparent velocities generally correspond to more devastating responses, which should be particularly considered during engineering practice.

Eco-morphodynamics of coastal wetlands

We survey the problem of the response of coastal wetlands to sea level rise. Two opposite views have traditionally been confronted. According to the former, on the geological time scale, coastal lagoons would be ‘ephemeral’ features. The latter view maintains that marshes would keep pace with relative sea level rise as, increasing the rate of the latter, the sedimentation rate would also increase. In any case, the timescale of morphodynamic evolution is of the order of centuries, which makes it not easily perceived. For example, in Venice, the diversion of the rivers debouching into the lagoon undertaken in the Renaissance has taken centuries to display its consequences (shift from depositional to erosional environment). This process accelerated in the last two centuries due to effects of the industrial revolution and of an enhanced sea level rise. Recent research has employed powerful computational techniques and advanced models of marsh vegetation. Zero-order modeling suggests that marsh equilibrium is possible, provided the rate of relative sea level rise does not exceed a threshold depending on the availability of minerogenic sediments, quantified through a loosely defined ambient sediment concentration. Analysis of the morphological interaction between adjacent morphological units suggests that the ‘equilibrium states’ identified by zero-order modeling correspond to marshes which either prograde or retreat, i.e., are not in equilibrium. Results suggest that available techniques, e.g., artificial replenishment of salt marshes or search for more productive halophytic species, will hardly allow Venice wetlands to keep up with a strong acceleration of sea level rise.

Multi-morphology cellular structure design with smooth transition of geometry and homogenized mechanical properties between adjacent cells

The recent development of additive manufacturing has led to an increased interest in the study of functionally graded cellular structures, which exhibit superior mechanical properties to the conventional uniform structures. However, connectivity is a critical problem that should be addressed, especially when multiple unit cell topologies are incorporated into a structure. In particular, inappropriate connectivity may cause stress concentration at the interfaces, reducing the structure’s lifespan. This paper proposes a method to design multi-morphology cellular structures that ensures smooth transition of geometry and homogenized mechanical properties between adjacent unit cells. The proposed method uses a genetic algorithm to design intermediate unit cells between a base and a target unit cell. Moreover, a customized parametric unit cell representation supports the design process. An implicit modeling method is adopted to synthesize the explicit 3D models. Numerical analyses demonstrate that the proposed method guarantees smooth transitions of geometry at the interfaces, variations in density, and homogeneous mechanical properties. Moreover, experimental characterization resulted in an increase of 78.7% in the elastic modulus and a reduction of 54.9% in the maximum von Mises stress for the structure designed with the proposed method when compared with that created using the conventional non-smoothing technique.

Provenance and depositional setting of the Buem structural unit (Ghana): Implications for the paleogeographic reconstruction of the West African and Amazonian cratons in Rodinia

We present new field, petrological and geochemical data, combined with U-Pb zircon ages and Lu-Hf isotope compositions for the sandstones of the Neoproterozoic Buem structural unit (BSU) of the Dahomeyide belt, and whole-rock geochemical data of BSU shale to investigate their provenance and depositional setting. The BSU contains siliciclastic sequences and fragments of oceanic lithosphere (pillow lavas, gabbro, and peridotite) that have archived the entire evolution of the Ediacaran West Gondwana Orogen (WGO), from early accretion to final amalgamation of the West African Craton (WAC) with the Benino-Nigerian Shield. Three broad groups of samples exist within the BSU in Ghana: those with dominantly older age fractions of 2300 – 1800 Ma, represented by samples from the base of the BSU; those with prominent 1700 – 1100 Ma zircons, occupying the middle part of the BSU; and those with significant 1000 – 970 Ma age fractions, forming the uppermost part of the BSU. Results from this study, together with published data on the BSU, and adjacent Togo structural unit and Voltaian Supergroup, reveal two main sedimentary sequences in the Dahomeyide belt, i.e., passive margin and foreland basin sequences with three potential provenances: Amazonian Craton, Benino-Nigerian Shield, ± WAC. This interpretation resembles that for the sedimentary rocks of the Borborema Province, NE Brazil, which implies similar evolution along the WGO. Thus, a long, >2500 km passive margin basin developed at 1000 – 700 Ma, which was subsequently inverted during the Braziliano/Pan-African plate convergence and collision, and the concomitant formation of the foreland basin during the assembly of the supercontinent Gondwana. Because a greater portion of the detritus in the BSU is probably from the Amazonian Craton, we propose that the WAC and the Amazonian Craton adjoined each other from the Paleoproterozoic onward within the supercontinents Rodinia and Gondwana, until the opening of the Atlantic Ocean.

Modeling, Planning Allow Successful Implementation of South Texas U-Turn Lateral

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 208801, “Successful Planning and Implementation of First South Texas U-Turn Lateral,” by Riley Schultz and Joe Kiefner, Chesapeake Energy. The paper has not been peer reviewed. Legacy fields require innovative solutions for developing capitally efficient projects within highly developed acreage blocks. As another tool to improve well economics, a U-turn lateral strategy was implemented in the Eagle Ford Shale. This wellbore trajectory resulted in capturing a 9,200-ft equivalent lateral length well in a 5,000-ft-wide lease space. This successful U-turn trajectory test has created new economic project opportunities for the company and has increased optionality within challenged lease spaces across the field. Well Overview In a single U-turn well, the horizontal wellbore turns 180° to create two parallel laterals in a map-view U shape. The successful U-turn project detailed in the complete paper was the first drilled in south Texas (Fig. 1). This resulted in significantly improved economics by using a horizontal turn as a hydrocarbon pathway, rather than an additional vertical section from a new well to gain the equivalent treatable lateral length. This well followed operator standards for south Texas Eagle Ford two-casing-string well design. A 9⅝-in. casing was set to protect shallow water zones, and an 8¾-in. production section was drilled for the remainder of the well (using 5½-in. drillpipe). 5½-in. production casing was then run to total depth (TD). 8¼-in. centralizers were placed on each joint of the casing, freely floating between the collars. The production section was drilled with oil-based mud, and a standard cement job was pumped. Conventional directional tools were used for the entirety of the drilling phase. The decision was made early in the planning phase of the well to forgo fracturing the turn portion of the wellbore and instead drill into the adjacent unit to conduct the turn to maximize the amount of optimally oriented lateral footage in the unit to be produced.

Missing Link in the Growth of Lead-Based Zintl Clusters: Isolation of the Dimeric Plumbaspherene [Cu4Pb22]4.

We report here the structure of an endohedral plumbaspherene, [Cu4Pb22]4–, the gold analogue of which was previously postulated to be a “missing link” in the growth of larger clusters containing three and four icosahedral subunits. The cluster contains two [Cu2Pb11]2– subunits linked through a Cu2Pb4 trigonal antiprism. Density functional theory reveals that the striking ability of mixed Pb/coinage metal Zintl clusters to oligomerize and, in the case of Au, to act as a site of nucleation for additional metal atoms, is a direct consequence of their nd10(n + 1)s0 configuration, which generates both a low-lying (n + 1)s-based LUMO and also a high-lying Pb-centered HOMO. Cluster growth and nucleation is then driven by this amphoteric character, allowing the clusters to form donor–acceptor interactions between adjacent icosahedral units or to additional metal atoms.

Broadband and high-efficiency photonic spin-Hall effect with all-metallic metasurfaces.

In this paper, all-metallic reflective metasurfaces comprising S-shape streamline structures are proposed to achieve the photonic spin-Hall effect with average cross-polarization conversion efficiency exceeding ∼84% in the range of 8-14 µm. By comparing with all-metallic nanobricks, it is demonstrated that the electric field coupling could be enhanced by constructing a similar split ring resonator between adjacent unit elements to further improve its efficiency and bandwidth. As a proof of concept, the photonic spin Hall effect and spin-to-orbit angular momentum conversion could be observed by two metadevices with the maximum diffraction efficiency of ∼95.7%. Such an all-metallic configuration may provide a platform for various high-efficiency electromagnetic components, catenary optics, and practical applications.

Oxidation Catalysis over Solid-State Keggin-Type Phosphomolybdic Acid with Oxygen Defects.

Keggin-type phosphomolybdic acid (PMo12O40), treated with pyridine (Py), forms a crystalline material (PyPMo-HT) following heat treatment under an inert gas flow at ∼420 °C. Although this material is known to have attractive catalytic properties for gas-phase oxidation, the origin of this catalytic activity requires clarification. In this study, we investigated the crystal structure of PyPMo-HT. PyPMo-HT comprises a one-dimensional array of Keggin units and pyridinium cations (HPy), with an HPy/Keggin unit ratio of ∼1.0. Two oxygen atoms were removed from the Keggin unit during crystal structure transformation, which resulted in an electron being localized on the Mo atom in close contact with the adjacent Keggin unit. Upon the introduction of molecular oxygen, electron transfer from this Mo atom resulted in the formation of an electrophilic oxygen species that bridged two Keggin units. The electrophilic oxygen species acted as a catalytically active oxygen species, as confirmed by the selective oxidation of propylene. PyPMo-HT showed excellent catalytic activity for the selective oxidation of methacrolein, with the methacrylic acid yield being superior to that obtained with PMo12O40 and comparable to that obtained with an industrial Keggin-type polyoxometalate (POM) catalyst. The oxidation catalysis observed over PyPMo-HT provides a deeper understanding of POM-based industrial catalytic processes.

3D Phase tensor inversion and Joint inversion using impedance and phase tensor components aiming better subsurface mapping and interpretation in Dhanjori basin, Singhbhum craton, eastern India

Dhanjori formation, a significant member of Singhbhum Craton, Eastern India, is well-known for its complex mineralogical character and huge content of Au-mineralization. This 2.1 Ga old Paleoproterozoic formation is composed of siliciclastic metasedimentary rocks interlayered with mafic/ultramafic volcanic rocks. Traces of gold has been spotted by many researchers in the sulfide-hosted mafic-ultramafic volcanic rocks and quartz pebble conglomerate units by different studies. Regional Audio Magnetotelluric (AMT) survey was conducted in 10 kHz–10 Hz frequency range over various lithological units of Dhanjori and adjacent Iron Ore Group. The key challenge faced during the analysis of magnetotelluric (MT) data is due to the presence of near-surface heterogeneities. The amplitude of the MT response gets distorted by galvanic effects which further create difficulties in modelling and inversion. If the effect is not removed in advance, it might lead to erroneous subsurface modelling and interpretations. On the contrary, the phase tensor data does not show any change in values even in the presence of galvanic distortion. Though phase tensors are the computed values from impedance tensor, still the response is free from any shallow level ambiguities unlike impedance data. We have performed 3-D inversion of phase tensor data to generate a conductivity model of Dhanjori basin. The objective was to verify whether the inclusion of phase tensor components in the inversion routine was able to provide some extra information that might add value to the analysis. Model from phase tensor inversion indicates only relative variation in the subsurface conductivity structure due to lack of amplitude information in the data. Hence, we also performed 3D joint inversion including both impedance and phase tensor components for obtaining the final conductivity model of Dhanjori to recover the absolute subsurface conductivity structure unaffected by galvanic distortion. Correlation of the conductivity model with available geoscientific information in Dhanjori and adjacent geological units helped us to relate the conductors to the sulfide mineralization prospect.

Isomeric Pair of E/Z Tetraphenylethene-Cored Luminogens Showing Distinguishing Mechanoresponsive Luminescence Turn-On and Two-Color Behavior

A pair of tetraphenylethylene (TPE)-based E/Z isomers (E-TPE2PD and Z-TPE2PD) using two dicyanovinyl groups as the electron-accepting moieties have been synthesized and separated successfully. Reversible E/Z isomerization for each isomer is achieved, in which the isomerization speed from E to Z is higher than that from Z to E. This pair of pure E/Z isomers exhibits obvious AIEE properties. Z-TPE2PD shows highly morphology-dependent solid-state photoluminescent properties, whose solid-state emission is red-shifted from 564 to 588 nm with an enhancement of crystalline degree together with a decrease in the emission intensity. In contrast, E-TPE2PD leads to a slightly blue-shifted emission of 5 nm dependent on its crystalline degree. To the best of our knowledge, the discrepancy in emissive color between TPE-based E and Z isomers is much larger than most of the reported ones. The absence and presence of π–π interactions between adjacent PDCV units observed in their crystal packing structures are suggested to be responsible for the distinct solid fluorescence of E and Z isomers. More interestingly, Z-TPE2PD exhibits blue-shifted mechanoresponsive luminescence (MRL) turn-on behavior when subjected to grinding, while E-TPE2PD shows a remarkable two-color photoluminescence (PL) nature. This paper offers a synthetic strategy by introducing strong polar dicyanovinyl groups into the TPE core to increase the molecular polarity difference of E and Z isomers and facilitate their separation, which makes the exploration of distinguishing morphology-dependent solid-state PL properties possible. This is the first report on an isomeric pair of E/Z tetraphenylethene-cored luminogens displaying different MRL turn-on and dichromic behavior.

Connections between unit cells in locally resonant metamaterials and their impact on the effectiveness of noise mitigation by its base structure

Locally resonant metamaterials (LRS) for sound and vibration mitigation have been a widely investigated topic in the field of acoustic in recent years. Many articles and projects describe fundamental problems of LRS design, numerical simulation, and laboratory measurements. However, there is a noticeable knowledge gap between laboratory prototypes and the mass production (development for a wide-scale implementation) of metamaterials structures. In general, the LRS prototypes require specific boundary conditions, for example, equal spacing between the individual resonators and separate attachment of each resonator to its base. These conditions allow for many simplifications in calculations. At the same time, these boundary conditions create a problem when it comes to the mass production of the LRS structures. Creating a connection between adjacent resonators would allow easier postprocessing of structures ex. attaching the structure to the base and keeping specified distances between resonators. This project investigates the possibilities of creating connections between adjacent unit cells and their influence on the simulation and measurement results. The effect on the simulated band gaps and sound transmission loss is investigated at the stage of numerical simulations. The prototypes of structures are 3D printed and tested. The laboratory measurement results are compared with simulations and further discussed.

On the learnability of level-based and unit-based tonal OCP generalizations: An artificial grammar learning study

In previous research of tonal phonology, contour tones were assumed to be phonologically presented not only as a sequence of level tones but also as a single unit. Obligatory Contour Principle (OCP) constraints, by extension, were thought to prohibit identical level tones associated to adjacent terminal nodes (OCP-Terminal) and identical adjacent tonal units (OCP-Unit). This proposal has nevertheless been challenged theoretically and empirically. This study seeks to offer new experimental evidence to help solve the debate by comparing the learnability of the two OCP generalizations in an artificial grammar learning paradigm. In Exp I, we exposed disyllabic tonal patterns conforming either to OCP-Terminal or to OCP-Unit to two target groups of learners, who were then tested if they could extend the hidden generalization to their auditory acceptability judgment of novel disyllabic items. Exp II had the same exposure phase but required learners to produce novel disyllabic items with tonal combinations of their choice. In both experiments, the two target groups demonstrated signs of learning target OCP generalizations from different channels. Crucially, learners implicitly acquired the OCP-Terminal generalization but only learned the OCP-Unit pattern as explicit knowledge. These findings led us to conclude that OCP-Unit may not be involved in implicit and automatized phonological computation.

Neurogenetic Heterochrony in Chick, Lizard, and Rat Mapped with Wholemount Acetylcholinesterase and the Prosomeric Model

In the developing brain, the phenomenon of neurogenesis is manifested heterotopically, that is, much the same neurogenetic steps occur at different places with a different timetable. This is due apparently to early molecular regionalization of the neural tube wall in the anteroposterior and dorsoventral dimensions, in a checkerboard pattern of more or less deformed quadrangular histogenetic areas. Their respective fate is apparently specified by a locally specific combination of active/repressed genes known as “molecular profile.” This leads to position-dependent differential control of proliferation, neurogenesis, differentiation, and other aspects, eventually in a heterochronic manner across adjacent areal units with sufficiently different molecular profiles. It is not known how fixed these heterochronic patterns are. We reexamined here comparatively early patterns of forebrain and hindbrain neurogenesis in a lizard (Lacerta gallotia galloti), a bird (the chick), and a mammal (the rat), as demonstrated by activation of acetylcholinesterase (AChE). This is an early marker of postmitotic neurons, which leaves unlabeled the neuroepithelial ventricular cells, so that we can examine cleared wholemounts of the reacted brains to have a birds-eye view of the emergent neuronal pattern at each stage. There is overall heterochrony between the basal and alar plates of the brain, a known fact, but, remarkably, heterochrony occurs even within the precocious basal plate among its final anteroposterior neuromeric subdivisions and their internal microzonal subdivisions. Some neuromeric units or microzones are precocious, while others follow suit without any specific spatial order or gradient; other similar neuromeric units remain retarded in the midst of quite advanced neighbors, though they do produce similar neurogenetic patterns at later stages. It was found that some details of such neuromeric heterochrony are species-specific, possibly related to differential morphogenetic properties. Given the molecular causal underpinning of the updated prosomeric model used here for interpretation, we comment on the close correlation between some genetic patterns and the observed AChE differentiation patterns.