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Sensory adaptation is the process whereby brain circuits adjust neuronal activity in response to redundant sensory stimuli. Although sensory adaptation has been extensively studied for individual neurons on timescales of tens of milliseconds to a few seconds, little is known about it over longer timescales or at the population level. We investigated population-level adaptation in the barrel field of the mouse somatosensory cortex (S1BF) using in vivo two-photon calcium imaging and Neuropixels recordings in awake mice. Among stimulus-responsive neurons, we found both adapting and facilitating neurons, which decreased or increased their firing, respectively, with repetitive whisker stimulation. The former outnumbered the latter by 2:1 in layers 2/3 and 4; hence, the overall population response of mouse S1BF was slightly adapting. We also discovered that population adaptation to one stimulus frequency (5 Hz) does not necessarily generalize to a different frequency (12.5 Hz). Moreover, responses of individual neurons to repeated rounds of stimulation over tens of minutes were strikingly heterogeneous and stochastic, such that their adapting or facilitating response profiles were not stable across time. Such representational drift was particularly striking when recording longitudinally across 8-9 days, as adaptation profiles of most whisker-responsive neurons changed drastically from one day to the next. Remarkably, repeated exposure to a familiar stimulus paradoxically shifted the population away from strong adaptation and toward facilitation. Thus, the adapting vs. facilitating response profile of S1BF neurons is not a fixed property of neurons but rather a highly dynamic feature that is shaped by sensory experience across days.

Changing ratios of stable carbon (δ13C) and nitrogen (δ15N) isotopes in consumer tissues reflect foraging patterns over time and can be used to inform studies on historically vulnerable populations. Northern fur seals (NFS; Callorhinus ursinus) at San Miguel Island (SMI), California, have been severely impacted by climate events such as El Niño and remain susceptible to future environmental disturbances, necessitating the need to further understand their foraging ecology. We analyzed sequential δ13C and δ15N values along single NFS whiskers sampled from five pups and five unrelated post-parturient females at SMI and reconstructed temporally aligned stable isotope profiles for each whisker. Pup profiles consistently showed increases in postnatal δ13C and δ15N values that likely stem from pup consumption of maternal milk and changes in maternal foraging locations after parturition. Adult female profiles indicated predominantly heterogeneous foraging strategies and minimal foraging outside the Southern California Bight. These findings provide initial characterizations of longitudinal, stable isotope-derived foraging data for NFS from SMI and offer insight into the inference of otariid foraging ecology with sequential δ13C and δ15N values. [ABSTRACT FROM AUTHOR]

The test conditions under which whiskers generated from galvanized steel sheets were investigated. Then, it was found that whiskers are generated when a temperature cycle that satisfies certain conditions is given. Based on the results, we estimated the correlation between heat stress and market stress in the test, and devised a method to determine an appropriate test period from the market temperature data. [ABSTRACT FROM AUTHOR]

Magnetoresistance of GaAs whiskers with concentrations in the vicinity to metal-insulator transition (MIT) 1017–1018 cm−3 were studied at low temperatures and high magnetic fields (up to 14 T). The whiskers were doped with Te during the growth. The whisker diameter ranges from 10 to 40 μm. Temperature dependence of the whisker resistance have shown metallic and semiconductor character in the proximity to MIT from various sides of the transition. Depending on doping level the character of the whisker magnetoresistance changes from linear positive to quadratic negative. The magnetoresistance of metallic whiskers is explained in terms of weak antilocalization (WAL) model. The specimens with semiconductor character of conductance revealed negative magnetoresistance, magnitude of which rises due to moving away from MIT and reach 15% for the whiskers with concentration 1017 cm−3. The possible reasons of the negative magnetoresistance are discussed. The effect observed is attributed to weak localization (WL) of charge carriers in the region of hopping conductance for the whiskers in the vicinity to MIT. A high negative magnetoresistance (NMR) for the whiskers of low dopant concentration is connected with subsurface conductance in the disordered upper layers of the whiskers due to their core-shell structure. [ABSTRACT FROM AUTHOR]

The development of additive manufacturing technique provides possibility to prepare SiC ceramics with complex shapes. However, defect control in the debinding and sintering stages is still a great challenge for the vat photopolymerized components. Here, SiC ceramics were manufactured by vat photopolymerization followed by liquid silicon infiltration, using SiC whiskers as the reinforcement. In the debinding stage, the SiC whiskers prevented the propagation of micro-cracks that induced by the formation and emission of gaseous substance. Also, the SiC whiskers provided channels for the infiltration of liquid silicon during sintering, thus the bulk density of the as-sintered SiC w /RBSC composite reached 2.95 g/cm3 at the whiskers fraction of 8 wt%. Because of the various toughening mechanisms introduced by SiC whisker, the flexural strength and Vickers hardness of the composite increased up to 352.2 MPa and 17.54 GPa, respectively. Thus, this work provides a new strategy to control micro-defects in vat photopolymerized SiC ceramics. [ABSTRACT FROM AUTHOR]

The mechanical recycling of discarded plastic products as resources for environmental preservation has recently gained research attention. In this context, it is necessary to use waste materials for fiber-reinforced thermoplastics (FRTP). Glass and carbon fibers are often damaged by shear and compression during melt-forming processes. To achieve a sustainable society, it is necessary for thermal recycling to produce minimal to no residue and for mechanical recycling to maintain the length of fibers used in FRTP to preserve their performance as a reinforcing agent. Aramid fibers (AFs) do not shorten during the melt-molding process, and their composites have excellent impact strength. On the other hand, plastics reinforced with glass or carbon fibers are reported to have a superior strength and modulus of elasticity compared to aramid fibers. This study investigates the dispersion of a carbon nanofiber (CNF), a whisker, as the third component in aramid-fiber-reinforced polypropylene (PP/AF). The results and discussion sections demonstrate how the dispersion of CNF in PP/AF can enhance the mechanical properties of injection-molded products without compromising their impact resistance. The proposed composition will have excellent material recyclability and initial mechanical properties compared to glass-fiber-reinforced thermoplastics. [ABSTRACT FROM AUTHOR]

Copyright of Industrial Minerals & Processing / Huagong Kuangwu yu Jiagong is the property of Industrial Minerals & Processing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Refractories / Naihuo Cailiao is the property of Naihuo Cailia (Refractories) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The darkness of the deep ocean limits the vision of diving predators, except when prey emit bioluminescence. It is hypothesized that deep-diving seals rely on highly developed whiskers to locate their prey. However, if and how seals use their whiskers while foraging in natural conditions remains unknown. We used animal-borne tags to show that free-ranging elephant seals use their whiskers for hydrodynamic prey sensing. Small, cheek-mounted video loggers documented seals actively protracting their whiskers in front of their mouths with rhythmic whisker movement, like terrestrial mammals exploring their environment. Seals focused their sensing effort at deep foraging depths, performing prolonged whisker protraction to detect, pursue, and capture prey. Feeding-event recorders with light sensors demonstrated that bioluminescence contributed to only about 20% of overall foraging success, confirming that whiskers play the primary role in sensing prey. Accordingly, visual prey detection complemented and enhanced prey capture. The whiskers' role highlights an evolutionary alternative to echolocation for adapting to the extreme dark of the deep ocean environment, revealing how sensory abilities shape foraging niche segregation in deep-diving mammals. Mammals typically have mobile facial whiskers, and our study reveals the significant function of whiskers in the natural foraging behavior of a marine predator. We demonstrate the importance of field-based sensory studies incorporating multimodality to better understand how multiple sensory systems are complementary in shaping the foraging success of predators.

Si 3 N 4 whisker scaffolds have great potentials owing to the superior properties of Si 3 N 4 and their unique porous structures. Obviously, the properties of the scaffolds are closely related to the morphology and distribution of phases, and the bonding between whiskers. This study proves that the above-mentioned microstructural features can be tailored to a great extent by the in - situ growth of secondary Si 3 N 4 products via carbothermal reduction and nitridation (CRN) of SiO 2 inside a β-Si 3 N 4 whisker network. Specifically, the yield and morphology (grain size, aspect ratio, etc.) of the CRN product are found to be strongly dependent on the composition and amount of the reactants (SiO 2 and C/SiO 2 molar ratio) and reaction temperature. When reacted at 1300 ℃, a distinctive microstructure is formed in which nano sized and CRN-derived Si 3 N 4 whiskers are uniformly distributed in the original micron sized whisker network. The whisker scaffolds reveal improved flexural strength if compared with that without CRN-derived Si 3 N 4. This finding indicates the formation of a strong bonding between the β-Si 3 N 4 whiskers by the growth of the CRN product. The measured low dielectric constant (2.6 ∼ 3.1) and low dielectric loss (<1.1 ×10−2) of the scaffolds makes them suitable for wave transmission application. [ABSTRACT FROM AUTHOR]

SiC reticulated porous ceramic with excellent strength and high-density ceramic struts was successfully prepared using the polymer replica method, followed by pressureless sintering under a buried charcoal atmosphere. First, a polyurethane (PU) template was coated with a Si slurry and then a SiC-containing slurry, and subsequently heated under the buried charcoal atmosphere. To ensure excellent coating ability of the slurries, the viscosity, thixotropy, and yield stresses of the Si slurry were optimized by adjusting the content of the thickening agent. During heating, Si in the coating layer reacted with the residual C and CO gas from the PU template and buried charcoal, forming SiC whiskers that filled hollow voids within the SiC struts. Additionally, catalyst ferric nitrate was added to the Si slurry to promote the generation and growth of SiC whiskers. As a result, when compared to the untreated SiC reticulated porous ceramic, the SiC reticulated porous ceramic pre-coated with Si layers exhibited significant improvements in mechanical strength and thermal shock resistance, despite minor differences in porosity. Furthermore, an industrial test conducted in the copper smelting industry showed that the structure of SiC reticulated porous ceramic, prepared in this study and used as filters, remained intact even after 7 days of continuous use. Meanwhile, a significant number of inclusions was adhered to the surfaces of the filters. Therefore, the processes combined with in-situ generation of SiC whiskers is an ideal and low-cost method for fabricating SiC filters with excellent properties. [ABSTRACT FROM AUTHOR]

Exploring ceramic-based self-lubricating materials with low coefficient of friction (COF) has become one of the hot directions to advance the service performance and life of high-end equipment. In this work, the tribological properties of multilayer graphene (MLG)/β-Si 3 N 4 whisker (β-Si 3 N 4w)/Si 3 N 4 ceramics were investigated. The effects of load and linear speed on the dry sliding COF were discussed. The friction-reducing and self-lubricating mechanisms of MLG and β-Si 3 N 4w were deeply analyzed according to the wear morphology and mechanical properties of Si 3 N 4 -based ceramics. The friction frequency was proposed to analyze the wear mechanism. Results indicated that MLG and β-Si 3 N 4w led to a breakthrough reduction in COF. At the load of 5–20 N, the COF reached an ultra-low level of 0.04–0.07, which was a further 89.86% lower than the reported studies. The comprehensive enhancement of mechanical properties and the existence of MLG lubricating film were the mainly responsible for the ultra-low COF. The COF of MLG/β-Si 3 N 4w /Si 3 N 4 ceramics raised to 0.24–0.31 at 50–200 mm/s, but it was still 33.88–47.64% lower than that of graphene/Si 3 N 4 ceramics. The increase in COF was attributed to the high wear induced by the raised friction frequency. The furrow wear and adhesive wear were the main wear forms of MLG/β-Si 3 N 4w /Si 3 N 4 ceramics. [ABSTRACT FROM AUTHOR]

Ceramic membranes with high porosity and excellent separation efficiency are necessary for the efficient treatment of large‐scale wastewaters. However, the conventional ceramic membranes are usually prepared by particles‐packing, which inhibits the advances of separation efficiency because of the low porosity and connectivity. Here, a fibrous ceramic membrane with mullite whiskers‐interlocked structure was prepared by gas‐solid reaction. The effects of aluminum fluoride (AlF3) on the formation and growth of mullite whiskers, and then the permeability and selectivity of the ceramic membranes were investigated. With the increase of AlF3 contents, the mullite phase evolved from needle‐like, rod‐like to flake‐like structure, thus the catalyst accelerated the growth of mullite whiskers in the diameter direction. For the ceramic membrane sintered at 1400°C, the porosity increased from 58% to 76% while the average pore sizes increased from 0.65 to 3.93 μm because of the whisker‐constructed structures. For the ceramic membrane sintered at 1450°C, the emulsion flux increased stably from 295 L/(m2·h) to 992 L/(m2·h) with the increase of trans‐membrane pressure, and the oil rejection exceeded 98%. Thus, this study provides a feasible strategy for the preparation of ceramic membranes with high porosity and excellent separation performances. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The mechanical recycling of discarded plastic products as resources for environmental preservation has recently gained research attention. In this context, it is necessary to use waste materials for fiber-reinforced thermoplastics (FRTP). Glass and carbon fibers are often damaged by shear and compression during melt-forming processes. To achieve a sustainable society, it is necessary for thermal recycling to produce minimal to no residue and for mechanical recycling to maintain the length of fibers used in FRTP to preserve their performance as a reinforcing agent. Aramid fibers (AFs) do not shorten during the melt-molding process, and their composites have excellent impact strength. On the other hand, plastics reinforced with glass or carbon fibers are reported to have a superior strength and modulus of elasticity compared to aramid fibers. This study investigates the dispersion of a carbon nanofiber (CNF), a whisker, as the third component in aramid-fiber-reinforced polypropylene (PP/AF). The results and discussion sections demonstrate how the dispersion of CNF in PP/AF can enhance the mechanical properties of injection-molded products without compromising their impact resistance. The proposed composition will have excellent material recyclability and initial mechanical properties compared to glass-fiber-reinforced thermoplastics.

The orientation of hydroxyapatite whiskers ( HAw ) is one of key to design and develop bioactive ceramics for bone regeneraction. Guided behavior based on the construction of magnetic anisotropy. In this study, magnetic nanoparticles Fe3O4 were loaded onto the surface of HAw by hydrothermal method, and magnetic HAw composites with excellent magnetic response characteristics were successfully prepared. The physicochemical properties and biological properties of magnetized HAw were systematically studied, and its orientation behavior in weak magnetic field was explored. The results show that ferric oxide ( Fe3 O4) nanoparticles are successfully loaded onto the surface of HAw, and the magnetized HAw has superparamagnetism and good magnetic response at room temperature, which can be manupulated by conventional permanent magnets. The alignment direction applied by the external magnetic field is effectively fixed by combining the magnetic field-induced grouting molding technology. The results of CCK-8 experiment show that magnetized HAw has no cytotoxicity. [ABSTRACT FROM AUTHOR]

Animals interact with their environment through mechanically active, mobile sensors. The efficient use of these sensory organs implies the ability to track their position; otherwise, perceptual stability or prehension would be profoundly impeded. The nervous system may keep track of the position of a sensorimotor organ via two complementary feedback mechanisms--peripheral reafference (external, sensory feedback) and efference copy (internal feedback). Yet, the potential contributions of these mechanisms remain largely unexplored. By training male rats to place one of their vibrissae within a predetermined angular range without contact, a task that depends on knowledge of vibrissa position relative to their face, we found that peripheral reafference is not required. The presence of motor cortex is not required either, except in the absence of peripheral reafference to maintain motor stability. Finally, the red nucleus, which receives descending inputs from motor cortex and cerebellum and projects to facial motoneurons, is critically involved in the execution of the vibrissa positioning task. All told, our results point toward the existence of an internal model that requires either peripheral reafference or motor cortex to optimally drive voluntary motion. [ABSTRACT FROM AUTHOR]

Aiming to efficiently remove submicron particulate matter (PM), a low pressure drop ceramic whisker membrane was prepared via precursor solution dip coating followed by high temperature firing. Aluminum nitrate 9-Hydrate and boric acid were used as the precursors for the formation of aluminum borate. A highly porous film comprising interconnected single phase 9Al 2 O 3 ·2B 2 O 3 whiskers of high aspect ratio, was successfully formed on an alumina support. Flue gas filtration tests indicated that as-fabricated ceramic whisker membrane exhibited outstanding filtration performance. More than 95 % PM in 0.3–1 µm was removed by using the as-prepared ceramic whisker membrane, and the pressure drop after three rounds of back blow regeneration remained stably at approximate only 1.3 times of the air pressure drop. This work provided a feasible approach to the preparation of a novel ceramic membrane with low pressure drop, and a novel strategy for high efficiency removal of submicron PM. [ABSTRACT FROM AUTHOR]

A series of nanopillar compression tests were performed on tungsten as a function of temperature using in situ transmission electron microscopy with localized laser heating. Surface oxidation was observed to form on the pillars and grow in thickness with increasing temperature. Deformation between 850 °C and 1120 °C is facilitated by long-range diffusional transport from the tungsten pillar onto adjacent regions of the Y2O3-stabilized ZrO2 indenter. The constraint imposed by the surface oxidation is hypothesized to underly this mechanism for localized plasticity, which is generally the so-called whisker growth mechanism. The results are discussed in context of the tungsten fuzz growth mechanism in He plasma-facing environments. The two processes exhibit similar morphological features and the conditions under which fuzz evolves appear to satisfy the conditions necessary to induce whisker growth.

We studied how the ratio of precursor titanium and boron powders influenced the combustion temperature and combustion velocity in the high-temperature self-propagating synthesis (SHS) mode, and the microstructure, phase composition, and mechanophysical properties of rods fabricated by SHS extrusion. The subject matters of the study were materials for which the as-batch phase compositions of products were TiB–(20–40) wt % Ti. The formation of boron solid solution in titanium was considered. Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and mechanical measurements implied the texture of the prepared materials (TiB whiskers were aligned in the direction in which the external pressure was applied). In all of the composites studied, the conductivity was close to the conductivity of undoped titanium; the electrical resistance increased slightly in response to increasing boron weight fraction. The three-point bending strength of the material increased by a factor of 1.7 at most as the weight fraction of boron solid solution in titanium increased from 20 to 40 wt %. [ABSTRACT FROM AUTHOR]

The development of flexible and wearable devices is mainly required for tactile sensing; as such devices can adapt to complicated nonuniform surfaces, they can be applied to the human body. Nevertheless, it remains necessary to simultaneously achieve small-scale, portable, and stable developments in such devices. Thus, this work aims at fabricating a novel, lightweight, ultra-flexible, and fiber-shaped coaxial structure with a diameter of 0.51 mm using polydimethylsiloxane/graphene/nylon material, based on piezoresistive and triboelectric principles. The piezoresistive-based robotic-hand-controlled sensor thus realized exhibits a response time of 120 ms and a fast recovery time of 55 ms. Further, the piezoresistive-based sensors effectively feature whisker/joystick-guided behaviors and also sense the human finger contact. Owing to the triboelectric-based self-powered nanogenerator behavior, the resulting sensor can convert mechanical motion into electrical energy, without adversely affecting human organs. Moreover, this triboelectric-based human finger sensor can be operated under different bending modes at specific angles. Notably, this multifunctional sensor is cost-effective and suitable for various applications, including robotic-hand-controlled operations in medical surgery, whisker/joystick motions in lightweight drone technology, and navigation with high-sensitivity components. [ABSTRACT FROM AUTHOR]

Preparation of mullite from high-alumina coal fly ash (CFA) has become one of the most important ways for high-value utilization. However, low Al2O3/SiO2 ratio, poor reaction activity and various impurities in fly ash led to poor quality of mullite products. Conventional sintering method requires addition of aluminum sources and sintering additives, and high synthesis temperature. This paper proposes a new technical route for preparation of mullite whiskers entirely from fly ash by molten salt method based on additive activation-acid leaching process. The growth process and synthesis mechanism of mullite whiskers in Na2SO4 molten salt from fly ash were systematically investigated, and the application of fly ash-derived mullite whiskers in electronic packaging toughening ceramic was also explored. The results show that leaching liquor containing Al3+, Na+, and SO42−, and amorphous silica slag can be separated and obtained after acid leaching of activated fly ash at 80 °C, and the fly ash-derived mullite whiskers with a length of about 1 μm can be synthesized from the mixture of crystalline products and silica slag by the proposed method under the optimal synthesis conditions. Using amorphous silica slag with higher dissolution activity as the silicon source, the nucleation of mullite whiskers with homogeneous nucleation process is promoted and highly monodispersed mullite whiskers derived from fly ash form. The fly ash-derived mullite whiskers can improve the mechanical strength, reduce the dielectric constant and dielectric loss of the composite ceramic substrates, and the dielectric constant and dielectric loss of the composite ceramic are the lowest 5.16 and 0.006, respectively, when the mullite addition content is 20 wt.%, indicating that they could be used as electronic packaging materials. This paper provides a novel pathway for synthesis of mullite whiskers and high-value utilization of fly ash.

The direct parametrisation method for invariant manifolds is used for model order reduction of forced-damped mechanical structures subjected to geometric nonlinearities. Nonlinear mappings are introduced, allowing one to pass from the degrees of freedom of the finite-element model to the normal coordinates. Arbitrary orders of expansions are considered for the unknown mappings and the reduced dynamics, which are then solved sequentially through the homological equations for both autonomous and time-dependent terms. It is emphasised that the two problems share a similar structure, which can be used for an efficient implementation of the non-autonomous added terms. Special emphasis is also put on the new resonance conditions arising due to the presence of the external forcing frequencies, which allow predicting phenomena such as parametric excitation and isolas formation. The method is then applied to structures of academic and industrial interest. First, the large amplitude vibrations of a forced-damped cantilever beam are studied. This example highlights that high-order non-autonomous terms are compulsory to correctly estimate the maximum vibration amplitude experienced by the structure. The birth of isolated solutions is also illustrated on this example. The cantilever is then used to show how quadratic coupling creates conditions for the excitation of the parametric instability, and that this feature is correctly embedded in the reduction process. A shallow arch excited with multi-modal forcing is then studied to detail different forcing effects. Finally, the approach is validated on a structure of industrial relevance, i.e. a comb-driven micro-electro-mechanical resonator. The accuracy and computational performance reported suggest that the proposed methodology can accurately predict the nonlinear dynamic response of a large class of nonlinear vibratory systems. [ABSTRACT FROM AUTHOR]

To realize the resource utilization of coal gangue, mullite whisker in-situ reinforced cordierite-mullite porous ceramics were synthesized using kaolin powder, coal gangue powder, talc powder, and aluminum hydroxide powder as main raw materials. Effects of the coal gangue addition (0,9%, 17%, 26% and 33%, by mass) and the AlF3 addition (0,1.5%, 2.0%, 2.5% and 3.0%, by mass) on the phase composition, the microstructure and the properties of the porous ceramics were studied. The results show that (1) the main mineral compositions of the samples are cordierite and mullite with the coal gangue addition≤= 17% and the AlF3 addition ≤2.5%; (2) raising the coal gangue addition obviously increases the bulk density and the cold compressive strength, but it is unfavorable to maintain the apparent porosity; raising the AlF3 addition reduces the bulk density and the cold compressive strength, but increases the apparent porosity; (3) with the increase of the coal gangue and the AlF3 additions, mullite whiskers have increased diameter and length to diameter ratio, showing square column-like or needle-like shapes; (4) added with 17% coal gangue and 2.5% AlF3, the porous ceramic fired at 1 350 °C for 2 h has the bulk density of 1.86 g ⋅ cm-3, the apparent porosity of 31.0% and the cold compressive strength of 27.8 MPa; the needle-like mullite whiskers in the porous ceramic form an interlocking structure and they have an average diameter of 0.5 µm and the length to diameter ratio >20. [ABSTRACT FROM AUTHOR]

Lithium disilicate (Li2Si2O5, referred as LD) glass ceramics with unique aesthetic properties are ideal dental restorative materials. However, their applications are limited due to the lower flexural strength than polycrystalline ceramics. Herein, micro-nano-LD whiskers were utilized to facilitate the formation of crystallization sites and further growth of crystals in SiO2-Li2O glasses during the heat treatment process. Meanwhile, an orthogonal experiment with four-factor three-level was designed, and the optimum heat treatment conditions for preparing LD glass-ceramics with excellent flexural strength were found. The order of influencing extent of heat treatment conditions is crystallization temperature > crystallization time > nucleation temperature > nucleation time. In addition, the crystallization behavior, phase formation, microstructure and flexural strength of glass were measured at different heat treatment temperatures. Remarkably, the optimal LD glass-ceramics sample has a strong flexural strength at 342 MPa, in which plentiful crystal grains with uniform and dense distribution are observed. These results indicate that micro-nano-LD whisker-reinforced glass-ceramics obtained by optimized heat treatment program offer a potential candidate for dental applications.

Alzheimer's disease is the most frequent form of dementia in elderly people. The triple transgenic (3xTg‐AD) mouse model of Alzheimer's Disease is important in biomedical research as these mice develop both neuropathological and behavioural phenotypes. However, their behavioural phenotype is variable, with findings depending on the specific task, as well as the age and sex of the mice. Whisker movements show motor, sensory and cognitive deficits in mouse models of neurodegenerative disease. Therefore, we examined whisker movements in 3, 12.5 and 17‐month‐old female 3xTg‐AD mice and their B6129S/F2 wildtype controls. Mice were filmed using a high‐speed video camera (500 fps) in an open arena during a novel object exploration task. Genotype and age differences were found in mice exploring the arena prior to object contact. Prior to whisker contact, the 3‐month‐old 3xTg‐AD mice had smaller whisker angles compared with the wildtype controls, suggesting an early motor phenotype in these mice. Pre‐contact mean angular position at 3 months and whisking amplitude at 17 months of age differed between the 3xTg‐AD and wildtype mice. During object contact 3xTg‐AD mice did not reduce whisker spread as frequently as the wildtype mice at 12.5 and 17 months, which may suggest sensory or attentional deficits. We show that whisker movements are a powerful behavioural measurement tool for capturing behavioural deficits in mouse models that show complex phenotypes, such as the 3xTg‐AD mouse model. [ABSTRACT FROM AUTHOR]

Whiskers have been extensively used in ceramics as excellent reinforcing phases during the past decades. Despite in-depth investigation of whisker-reinforced ceramics (WRC), however, the time-consuming, environmentally unfriendly, content design blindness of experimental method as well as pathogenicity of whiskers force people to explore quick and green research approaches. Therefore, this work aims at developing a modeling approach of WRC and predicting the mechanical properties of WRC, thereby compensating for the disadvantages of traditional experimental method. Initially, a modeling approach of WRC based on Voronoi tessellation was presented. Then, taking β-Si 3 N 4w and Si 3 N 4 as research objects, the prediction models of mechanical properties of 0–6 wt% β-Si 3 N 4w -reinforced Si 3 N 4 ceramics (SWRSC) were established. Finally, the effect of β-Si 3 N 4w content on mechanical properties of Si 3 N 4 -based ceramics was discussed, and the enhancement mechanism of β-Si 3 N 4w was revealed. Results indicated that the flexural strength of SWRSC was significantly advanced with increasing β-Si 3 N 4w content. Crack deflection and intergranular fracture induced by β-Si 3 N 4w as well as load-bearing effect of β-Si 3 N 4w were the mainly responsible for the reinforcement of Si 3 N 4 -based ceramics. The enhancement mechanisms, previously observed experimentally, were effectively simulated. The fracture toughness reached a maximum of 6.17 MPa m1/2 when β-Si 3 N 4w amount was 1 wt%, which was approximately 36.50% higher than monolithic Si 3 N 4 ceramic. The predicted value of β-Si 3 N 4w optimal content was consistent with relevant experimental conclusions. When β-Si 3 N 4w content was 3 wt%, the hardness of Si 3 N 4 -based ceramics reached the maximum value of 23.21 GPa. The effectiveness of prediction results and the presented modeling method were confirmed by comparing with related test values. [ABSTRACT FROM AUTHOR]

Immune systems play a critical role in the regulation of bone formation and homeostasis, which arouses a growing interest in the development of biomaterials that can modulate both immune response and osteogenesis. In this study, biphasic calcium phosphate (BCP) ceramics were modified with different whiskered surface, and their effects on macrophage polarization and functional status were investigated. The results showed that compared to BCP-W ceramics with long and solid whiskers, BCP-HW ceramics with short and hollow whiskers surface were conducive to protein adsorption and macrophage elongation. Furthermore, BCP-HW ceramics down-regulated the expression of M1 macrophage markers (II1β, Tnfα, and iNos), promoted the expression of M2 macrophage markers (Il10 and Arg) and growth factors (Tgfβl and Bmp2), which might be attributed to the differential integrin expression regulated by different whisker structures. The conditioned medium derived from the supernatant of macrophage/whiskered ceramic co-culture was further used to culture MC3T3-E1 pre-osteoblasts to evaluate the effects of whiskered ceramic-mediated macrophage secretion on osteogenesis in vitro. Compared with BCP-W ones, the secretion pattern induced by BCP-HW ceramics could promote the expression of bone markers in pre-osteoblasts, which might due to the activation of intracellular signaling cascades like BMP/Smad and TGF-β/Smad signaling pathways. A murine intramuscular implantation model suggested that after implantation for 1, 2, and 3 weeks, BCP-HW ceramics drove the switch of macrophages to ARG+ wound-healing M2 phenotype, while BCP-W ceramics increased the proportion of iNOS+ M1 inflammatory macrophages. At 2 months, only BCP-HW could induce ectopic bone formation. Taken together, these results indicated that BCP ceramics with hollow whiskers were capable of creating a proper inflammatory microenvironment to induce bone formation. These whiskered BCP ceramics with good osteo-immunomodulatory capacity hold promise in serving as bone grafts to achieve desired bone repair and regeneration. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride (h-BN) is a novel non-metallic material which is newly discovered in the field of photocatalysis due to its high surface area, excellent optical features and high electrical conductivity. Herein, hexagonal boron nitride whiskers were fabricated by using the polymeric precursor method and, the photocatalytic degradation performance was measured towards tetracycline antibiotic under visible-light-illumination. The morphological, physical, and optical features of the catalyst were identified by several characterization analyses. The characteristic peaks associated with the hexagonal phase of boron nitride were determined and high crystallinity of h-BN was confirmed by X-ray diffraction analysis. The characteristic B-N absorption peaks were detected in the Fourier transfer infrared spectrum. Brunauer- Emmet-Teller specific surface area of the boron nitride catalyst was calculated as 1019 m2/g which was relatively high, supplying abundant active regions to interact with the target pollutant. In photocatalytic degradation experiments, 91.9% of tetracycline decomposition was achieved within 180 min with a catalyst dosage of 0.2 g/L and initial concentration of 10 mg/L. The outstanding catalytic activity of the h-BN catalyst was attributed to the high surface area and negatively charged groups on the surface which captured the photo-induced holes and inhibited the recombination rate of charge carriers. These findings highlight the potential application of h-BN in the field of photocatalytic processes. [ABSTRACT FROM AUTHOR]

Metal—organic framework-derived materials have attracted significant attention in the applications of functional materials. In this work, the rod-like nickel-based metal—organic frameworks were first synthesized and subsequently employed as the hard templates and nickel sources to prepare the whisker-shaped nickel phyllosilicate using a facile hydrothermal technology. Then, the nickel phyllosilicate whiskers were evaluated to enhance the mechanical, thermal, flammable, and tribological properties of epoxy resin. The results show that adequate nickel phyllosilicate whiskers can disperse well in the matrix, improving the tensile strength and elastic modulus by 13.6% and 56.4%, respectively. Although the addition of nickel phyllosilicate whiskers could not obtain any UL-94 ratings, it enhanced the difficulty in burning the resulted epoxy resin nanocomposites and considerably enhanced thermal stabilities. Additionally, it was demonstrated that such nickel phyllosilicate whiskers preferred to improve the wear resistance instead of the antifriction feature. Moreover, the wear rate of epoxy resin nanocomposites was reduced significantly by 80% for pure epoxy resin by adding 1 phr whiskers. The as-prepared nickel phyllosilicate whiskers proved to be promising reinforcements in preparing of high-performance epoxy resin nanocomposites. [ABSTRACT FROM AUTHOR]

Atypical sensory processing is common in autism, but how neural coding is disrupted in sensory cortex is unclear. We evaluate whisker touch coding in L2/3 of somatosensory cortex (S1) in Cntnap2 −/− mice, which have reduced inhibition. This classically predicts excess pyramidal cell spiking, but this remains controversial, and other deficits may dominate. We find that c-fos expression is elevated in S1 of Cntnap2 −/− mice under spontaneous activity conditions but is comparable to that of control mice after whisker stimulation, suggesting normal sensory-evoked spike rates. GCaMP8m imaging from L2/3 pyramidal cells shows no excess whisker responsiveness, but it does show multiple signs of degraded somatotopic coding. This includes broadened whisker-tuning curves, a blurred whisker map, and blunted whisker point representations. These disruptions are greater in noisy than in sparse sensory conditions. Tuning instability across days is also substantially elevated in Cntnap2 −/− . Thus, Cntnap2 −/− mice show no excess sensory-evoked activity, but a degraded and unstable tactile code in S1. [Display omitted] • Characterizes sensory coding in S1 cortex in the Cntnap2 −/− mouse model of autism • Broad tuning and blurred, unstable maps, but no excess sensory-evoked spiking • Reduced inhibition is associated with degraded, unstable sensory coding in Cntnap2 −/− mice Wang and Feldman characterize tactile coding abnormalities in whisker S1 cortex in the Cntnap2 −/− mouse model of autism. These mice show multiple signs of degraded sensory coding, including blurred maps and unstable tuning, but not excess spiking. Impaired discriminative coding may be a common feature of the sensory cortex in autism. [ABSTRACT FROM AUTHOR]

The trial-and-error method used in ceramics research has certain limitations such as the high blindness of material component design. Moreover, calculations of the toughness of ceramics using the extended finite element method, which is the most broadly applied technique, are complicated. To overcome these issues, in this study, multilayer graphene (MLG)/Si 3 N 4 whisker (Si 3 N 4w)-reinforced Si 3 N 4 ceramics (MWSCs) were used as the model material, and the modeling of MWSCs was conducted using Voronoi tessellation. Additionally, a more concise novel approach was applied for the prediction of the fracture toughness of MWSCs. Furthermore, the optimal MLG and Si 3 N 4w contents were predicted, and then they were verified by fabricating MWSCs using spark plasma sintering (SPS). Simulation results indicated that the optimum MLG and Si 3 N 4w contents to enable the toughness and hardness to reach the maximum values (9.87 MPa·m1/2 and 23.19 GPa) were 1 wt% and 3 wt%, which were consistent with the experimental results. Consequently, the effectiveness of the proposed method was verified. Moreover, the experimental values of the maximum fracture toughness and hardness were 11.04 MPa·m1/2 and 20.29 GPa, which were 47.20% and 12.10% higher than those of Si 3 N 4 ceramics reinforced with 1 wt% MLG, respectively. The synergistic toughening effects of MLG and Si 3 N 4w were significantly reflected. The load-bearing effect, bridging, and crack deflection induced by MLG and Si 3 N 4w were the key reasons for the improvement in the mechanical properties of MWSCs. [ABSTRACT FROM AUTHOR]

The pretreated desulfurization gypsum was used as raw material, the sulfuric acid was used to adjust the pH value of the reaction solution, and the desulfurization gypsum whiskers were prepared by hydrothermal method to realize green production. Through the recycling of filtrate with or without reagent compensation, the effect of cycle number of filtrate on the quality of whiskers, pH value of solution and concentration of Na+ was studied. The results show that, with the increase of cycle number of filtrate, the pH value of filtrate gradually increases, but the concentration of Na+ decreases and its loss is from 27. 3% to 34. 6% in the condition of no reagent compensation. When H2 SO4 and NaCl are used to compensate the reaction solution, the effect of cycle number of filtrate on the concentration of Ca2 + is slight before and after reaction. However, the cycle number of filtrate has an obviously effect on the crystal morphology, aspect ratio and quality of whiskers. When the cycle number of filtrate is less than 5, the quality of prepared whiskers is relatively good. [ABSTRACT FROM AUTHOR]

Inspired by the surface structure of lotus leaves, micro–nano hierarchical surface structures have been widely used for designing superhydrophobic surfaces. However, the conventionally designed superhydrophobic surface structures are fragile. In this study, a layer of micron-sized mullite whiskers was grown using molten salt on the surface of BaAl 2 Si 2 O 8 (BAS) glass ceramics. Subsquently, SiO 2 nanoparticles modified with 1H,1H,2H,2H-perfluorodecyltriethoxysilane were sprayed onto the whisker layer to form a superhydrophobic surface. The nanoparticles exhibit superhydrophobicity, which is protected by the whisker layer containing pores and bulges. This prohibits direct contact between the nanoparticles and external objects. Contact and rolling angle tests indicated that the surface contact angle of the micro–nano hierarchical structure is 158° and the rolling angle is less than 10°. The stability of the superhydrophobic surface was tested through ultraviolet light, long-time immersion in solutions with various pH values, water scouring, and sandpaper abrasion. The results showed that the contact angle is greater than 150°. This study is expected to provide a simple and effective method for fabricating superhydrophobic surfaces on ceramics on a large scale. [ABSTRACT FROM AUTHOR]

The addition of CaF2@SiO2 and SiC whiskers to ceramic tools can improve their flexural strength and fracture toughness, reduce surface damage, and improve their cutting performance. The cutting experiments showed that under the same cutting conditions, the surface roughness of the workpiece processed with the Al2O3/TiC/SiC/CaF2@SiO2 (ATSC10) tool was significantly lower than that of the workpiece processed with the Al2O3/TiC/ SiC (ATS) tool. Additionally, the main cutting force and cutting temperature when cutting with the ATSC10 tool were lower by 30 and 31.7%, respectively. These results were attributed to the precipitation of CaF2 from the nanocoated particles during cutting and the formation of a uniform and continuous lubricating film on the surface of the tool. The wear on the front surface of the ATS tool was mainly adhesive, and that on the back tool surface was mainly abrasive. For ATSC10, the main forms of wear on the tool front surface were adhesive and abrasive, whereas the main form of wear on the tool back surface was abrasive with slight adhesive wear. The addition of nano-coated particles and whiskers improved the mechanical properties of the cutting tool while maintaining good cutting performance. [ABSTRACT FROM AUTHOR]

Neural activity exhibits oscillations, bursts, and resonance, enhancing responsiveness at preferential frequencies. For example, theta-frequency bursting and resonance in granule cells facilitate synaptic transmission and plasticity mechanisms at the input stage of the cerebellar cortex. However, whether theta-frequency bursting of Purkinje cells is involved in generating rhythmic behavior has remained neglected. We recorded and optogenetically modulated the simple and complex spike activity of Purkinje cells while monitoring whisker movements with a high-speed camera of awake, head-fixed mice. During spontaneous whisking, both simple spike activity and whisker movement exhibit peaks within the theta band. Eliciting either simple or complex spikes at frequencies ranging from 0.5 to 28 Hz, we found that 8 Hz is the preferred frequency around which the largest movement is induced. Interestingly, oscillatory whisker movements at 8 Hz were also generated when simple spike bursting was induced at 2 and 4 Hz, but never via climbing fiber stimulation. These results indicate that 8 Hz is the resonant frequency at which the cerebellar-whisker circuitry produces rhythmic whisking. [ABSTRACT FROM AUTHOR]

Aluminum nitride (AlN) usually exhibits a microstructure consisting of equiaxed grains. However, these grains do not allow for the positive control of the microstructure and mechanical properties of AlN. In this work, we attempted to control the microstructure of AlN through the addition of whiskers and investigated the relationship between the microstructure and mechanical properties. The sintered AlN showed a microstructure consisting of large, rod-like grains, which originated from the whiskers. Furthermore, the microstructure varied with the size and amount of whiskers added, and so did the flexural strength and fracture toughness. The flexural strength and fracture toughness of the whisker-added AlN samples ranged from 197 to 267 MPa and 5.4 to 6.4 MPa m1/2, respectively. In contrast, those of AlN without whiskers were 336 MPa and 3.1 MPa m1/2, respectively.

The darkness of the deep ocean limits the vision of diving predators, except when prey emit bioluminescence. It is hypothesized that deep-diving seals rely on highly developed whiskers to locate their prey. However, if and how seals use their whiskers while foraging in natural conditions remains unknown. We used animal-borne tags to show that free-ranging elephant seals use their whiskers for hydrodynamic prey sensing. Small, cheek-mounted video loggers documented seals actively protracting their whiskers in front of their mouths with rhythmic whisker movement, like terrestrial mammals exploring their environment. Seals focused their sensing effort at deep foraging depths, performing prolonged whisker protraction to detect, pursue, and capture prey. Feedingevent recorders with light sensors demonstrated that bioluminescence contributed to only about 20% of overall foraging success, confirming that whiskers play the primary role in sensing prey. Accordingly, visual prey detection complemented and enhanced prey capture. The whiskers' role highlights an evolutionary alternative to echolocation for adapting to the extreme dark of the deep ocean environment, revealing how sensory abilities shape foraging niche segregation in deep-diving mammals. Mammals typically have mobile facial whiskers, and our study reveals the significant function of whiskers in the natural foraging behavior of a marine predator. We demonstrate the importance of fieldbased sensory studies incorporating multimodality to better understand how multiple sensory systems are complementary in shaping the foraging success of predators. [ABSTRACT FROM AUTHOR]

The whiskers of rodents are a key sensory organ that provides critical tactile information for animal navigation and object exploration throughout life. Previous work has explored the developmental sensory-driven activation of the primary sensory cortex processing whisker information (wS1), also called barrel cortex. This body of work has shown that the barrel cortex is already activated by sensory stimuli during the first postnatal week. However, it is currently unknown when over the course of development these stimuli begin being processed by higher-order cortical areas, such as secondary whisker somatosensory area (wS2). Here we investigate the developmental engagement of wS2 by whisker stimuli and the emergence of corticocortical communication from wS1 to wS2. Using in vivo wide-field imaging and multielectrode recordings in control and conditional KO mice of either sex with thalamocortical innervation defects, we find that wS1 and wS2 are able to process bottom-up information coming from the thalamus from birth. We also identify that it is only at the end of the first postnatal week that wS1 begins to provide functional excitation into wS2, switching to more inhibitory actions after the second postnatal week. Therefore, we have uncovered a developmental window when information transfer between wS1 and wS2 reaches mature function. [ABSTRACT FROM AUTHOR]

While cells within barrel cortex respond primarily to deflections of their principal whisker (PW), they also exhibit responses to non-principal, or adjacent, whiskers (AWs), albeit responses with diminished amplitudes and longer latencies. The origin of multiwhisker receptive fields of barrel cells remains a point of controversy within the experimental literature, with three contending possibilities: (i) barrel cells inherit their AW responses from the AW responses of thalamocortical (TC) cells within their aligned barreloid; (ii) the axons of TC cells within a barreloid ramify to innervate multiple barrels, rather than only terminating within their aligned barrel; (iii) lateral intracortical transmission between barrels conveys AW responsivity to barrel cells. In this work, we develop a detailed, biologically plausible model of multiple barrels in order to examine possibility (iii); in order to isolate the dynamics that possibility (iii) entails, we incorporate lateral connections between barrels while assuming that TC cells respond only to their PW and that TC cell axons are confined to their home barrel. We show that our model is capable of capturing a broad swath of experimental observations on multiwhisker receptive field dynamics within barrels, and we compare and contrast the dynamics of this model with model dynamics from prior work in which employ a similar general modeling strategy to examine possibility (i). [ABSTRACT FROM AUTHOR]

Bismuth-borate glass, 40Bi2O3–60B2O3 (mol.%), was prepared and acted as a braze to join sapphire in air. Ahead of brazing, basic properties of glass were investigated, including structure and thermal parameters. The thermal expansion test showed that CTE of glass was 8.4 × 10−6/°C in period from 20 to 450 °C, suggesting a good thermal compatibility with sapphire. Bi45BO69 was the main crystalline phase in glass according to DSC analysis [BiO6], [BO3] and [BO4] were major units in 40Bi2O3–60B2O3 glass on the basis of FT-IR spectra analysis.In addition, the wetting behavior of the 40Bi2O3–60B2O3 glass on the sapphire substrate was favourable. Thereafter, sapphire plates were joined at 700 °C for 0 and 20 min, respectively. The results showed that Al4B2O9 whiskers grew in joint when holding for 20 min due to a reaction between 40Bi2O3–60B2O3 glass braze and sapphire. The shear strength was improved greatly as a result of Al4B2O9 whiskers’ appearance.

Of large length-to-diameter ratio and specific area, inorganic whiskers were widely applied for polymer reinforcement. As a well-known nanofiller, titanium dioxide (TiO 2) has been welcome by polymer engineering, mostly for whitening with spherical shapes favored. To date, there have been no TiO 2 whiskers reported for polymer reinforcement. In this work, a rutile type TiO 2 whisker was compounded with polyamide 66 (PA66) to prepare nanocomposites with surficial modification being conducted to further improve the compatibility between them. It was found that the rutile-type TiO 2 whisker significantly improves the mechanical properties of PA66 at high loadings and the performance went better when surficial modification for it was applied. Under 50 wt% addition of TiO 2 whisker either modified or not, the tensile strength, tensile modulus, flexural strength, flexural modulus, impact strength and heat deformation temperature of prepared PA66 composites were respectively increased by 52 %, 279 %, 44 %, 313 %, 20 %, 199 % and 84 %, 279 %, 88 %, 303 %, 114 %, 207 %, comparing with the pristine PA66. The mechanism regarding the overall reinforcement was analyzed, which was attributed to the shape-relevant multiple interactions between TiO 2 and PA66. Besides, the improved adhesion due to strong stable chemical bonding by surficial modification of fillers, is also accountable. [Display omitted] [ABSTRACT FROM AUTHOR]

Novel Zn-MAX phases like Ti 2 ZnC were synthesized in the literature by the reaction between Lewis acid salts like ZnCl 2 and the MAX phase. The interactions between the Cr–Al–B MAB phase contained in the PLS coating formed during HDA of Fe–Cr–B cast steel and five types of molten chloride salts (ZnCl 2 and SnCl 2) were investigated. The results showed that the Cr-(Al, Zn)–B and Cr-(Al, Sn)–B MAB phase solid solution were formed as the PLS coating reacted with the molten ZnCl 2 and SnCl 2 , respectively, through topochemical reaction. Zn and Sn could not coexist in the A-site Cr–Al–B MAB phase solid solution, and the replacement ability of Sn2+ contained in molten salt was much stronger than that of Zn2+. Zn and Sn whiskers could spontaneously grow on the Cr-(Al, Zn)–B and Cr-(Al, Sn)–B MAB phase solid solution respectively. • Interactions between Cr–Al–B MAB phase and molten chloride salts (SnCl 2 and ZnCl 2) were firstly studied. • Cr-(Al, Zn)–B and Cr-(Al, Sn)–B MAB phase solid solution were formed as the PLS coating reacted with the molten ZnCl 2 and SnCl 2 respectively. • Zn and Sn could not coexist in the A-site Cr–Al–B MAB phase solid solution. • The replacement ability of Sn2+ contained in molten salt was much stronger than that of Zn2+. • Zn and Sn whiskers could spontaneously grow on the Cr-(Al, Zn)–B and Cr-(Al, Sn)–B MAB phase solid solution respectively. [ABSTRACT FROM AUTHOR]

During active sensation, sensors scan space in order to generate a representation of the outside world. However, since spatial coding in sensory systems is typically addressed by measuring receptive fields in a fixed, sensor-based coordinate frame, the cortical representation of scanned space is poorly understood. To address this question, we probed spatial coding in the rodent whisker system using a combination of two-photon imaging and electrophysiology during active touch. We found that surround whiskers powerfully transform the cortical representation of scanned space. On the single-neuron level, surround input profoundly alters response amplitude and modulates spatial preference in the cortex. On the population level, surround input organizes the spatial preference of neurons into a continuous map of the space swept out by the whiskers. These data demonstrate how spatial summation over a moving sensor array is critical to generating population codes of sensory space.

We compare the circuit and cellular mechanisms for homeostatic plasticity that have been discovered in rodent somatosensory (S1) and visual (V1) cortex. Both areas use similar mechanisms to restore mean firing rate after sensory deprivation. Two time scales of homeostasis are evident, with distinct mechanisms. Slow homeostasis occurs over several days, and is mediated by homeostatic synaptic scaling in excitatory networks and, in some cases, homeostatic adjustment of pyramidal cell intrinsic excitability. Fast homeostasis occurs within less than 1 day, and is mediated by rapid disinhibition, implemented by activity-dependent plasticity in parvalbumin interneuron circuits. These processes interact with Hebbian synaptic plasticity to maintain cortical firing rates during learned adjustments in sensory representations.This article is part of the themed issue 'Integrating Hebbian and homeostatic plasticity'.

Zinc borate having the formula of 4ZnO·B2O3·H2O has been used as a fire retardant for polymers requiring high processing temperatures since it has a high dehydration temperature (around 415°C). The effects of reaction time, reaction temperature were investigated on the heterogeneous reaction between solid zinc oxide and boric acid solution. A stoichiometric amount of zinc oxide and 5.0% excess boric acid were used in experiments and the other parameters, mixing speed (1700 rpm), the solid-liquid ratio of 20%, and the amount of seed crystal (3.9% wt) were kept constant for all experiments. A 91.1% conversion was obtained at 120°C for 5 h of reaction time. Precipitated product was filtered and washed by hot water to remove the excess boric acid. Finally it was dried until reaching to a constant mass in an air circulating oven at 105°C. Powder products were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). FTIR spectrum and XRD pattern of powders are consistent with data of the zinc borate given in the literature. According to SEM analysis, whiskers are less than 1 μm in diameter and their lengths are in the range of 1–10 μm.

Whisker stimulation in awake mice evokes transient suppression of simple spike probability in crus I/II Purkinje cells. Here, we investigated how simple spike suppression arises synaptically, what it encodes, and how it affects cerebellar output. In vitro , monosynaptic parallel fiber (PF)-excitatory postsynaptic currents (EPSCs) facilitated strongly, whereas disynaptic inhibitory postsynaptic currents (IPSCs) remained stable, maximizing relative inhibitory strength at the onset of PF activity. Short-term plasticity thus favors the inhibition of Purkinje spikes before PFs facilitate. In vivo , whisker stimulation evoked a 2–6 ms synchronous spike suppression, just 6–8 ms (∼4 synaptic delays) after sensory onset, whereas active whisker movements elicited broadly timed spike rate increases that did not modulate sensory-evoked suppression. Firing in the cerebellar nuclei (CbN) inversely correlated with disinhibition from sensory-evoked simple spike suppressions but was decoupled from slow, non-synchronous movement-associated elevations of Purkinje firing rates. Synchrony thus allows the CbN to high-pass filter Purkinje inputs, facilitating sensory-evoked cerebellar outputs that can drive movements. • Brief well-timed inhibition of Purkinje cells encodes tactile sensory onset • Broadly timed excitation encodes motor-related signals in the same cells • Short-term synaptic plasticity provides a mechanism for sensory-onset detection • The CbN reacts to fast changes in Purkinje inhibition but filters slow changes Brown et al. find that differential short-term plasticity of excitatory and inhibitory synapses lets Purkinje cells encode touch and whisking with a dual simple spike code. Sensory onset evokes well-timed spike suppression. Motor-related signals evoke slow spike rate increases. CbN targets fire strongly during the former but filter the latter. [ABSTRACT FROM AUTHOR]

In ferrotitanium slag-based Al 2 O 3 -SiC-C castables, owing to the presence of more impurities in the ferrotitanium slag, the liquid content at high temperatures is extremely high, which reduces the performance of the material. In this study, the Al-Si alloy powder was hydrated, and then pretreated Al-Si alloy powder (PASAP) was used to replace Si powder and micro-silica to reduce the content of liquid in the ferrotitanium slag-based Al 2 O 3 -SiC-C castables. Compared with the sample without PASAP, the sample with 5 wt% PASAP formed numerous whiskers in situ, and the hot modulus of rupture increased by 167%. Moreover, the decrease in the liquid content of the material and the dissolution of the molten slag by Al 2 O 3 led to an increase in the slag viscosity. The slag corrosion index of the sample with 5 wt% PASAP is decreased by 67%. • In this study, we proposed a pretreated Al-Si alloy powder for replacing Si powder and micro-silica. • After the introduction of pretreated Al-Si alloy powder, a large number of whiskers are formed. • The formation of whiskers significantly improves the mechanical properties and slag resistance of material. [ABSTRACT FROM AUTHOR]