Reconciling the object and spatial processing views of the perirhinal cortex through task-relevant unitization

The perirhinal cortex is situated on the border between sensory association cortex and the hippocampal formation. It serves an important function as a transition area between the sensory neocortex and the medial temporal lobe. While the perirhinal cortex has traditionally been associated with object coding and the "what" pathway of the temporal lobe, current evidence suggests a broader function of the perirhinal cortex in solving feature ambiguity and processing complex stimuli. Besides fulfilling functions in object coding, recent neurophysiological findings in freely moving rodents indicate that the perirhinal cortex also contributes to spatial and contextual processing beyond individual sensory modalities. Here, we address how these two opposing views on perirhinal cortex-the object-centered and spatial-contextual processing hypotheses-may be reconciled. The perirhinal cortex is consistently recruited when different features can be merged perceptually or conceptually into a single entity. Features that are unitized in these entities include object information from multiple sensory domains, reward associations, semantic features and spatial/contextual associations. We propose that the same perirhinal network circuits can be flexibly deployed for multiple cognitive functions, such that the perirhinal cortex performs similar unitization operations on different types of information, depending on behavioral demands and ranging from the object-related domain to spatial, contextual and semantic information

Multifunctional Heterogeneous Catalysts for the Selective Conversion of Glycerol into Methyl Lactate

Multifunctional catalytic systems consisting of physical mixtures of Au nanoparticles (2–3 nm) supported on metal oxides and Sn-MCM-41 nanoparticles (50–120 nm) were synthesized and investigated for the selective conversion of glycerol to methyl lactate. The Au catalyst promotes the oxidation of glycerol to trioses, whereas the solid acid Sn-MCM-41 catalyzes the rearrangement of the intermediate trioses to methyl lactate. Among the supported Au nanoparticles, Au/CuO led to the highest yield and selectivity toward methyl lactate, while the Sn-MCM-41 nanoparticles showed much better catalytic performance than a benchmark solid acid catalyst (USY zeolite). The activity of the multifunctional catalytic system was further optimized by tuning the calcination temperature, the gold loading in the Au/CuO catalyst, and the Au/Sn molar ratio, reaching 63% yield of methyl lactate (ML) at 95% glycerol conversion. This catalytic system also showed excellent reusability. The catalytic results were rationalized on the basis of a detailed characterization by means of TEM, N₂-physisorption, UV–vis spectroscopy, and by FT-IR using probe molecules (CO and ethanol)

Theta Phase Entrainment of Single-Cell Spiking in Rat Somatosensory Barrel Cortex and Secondary Visual Cortex Is Enhanced during Multisensory Discrimination Behavior

Phase entrainment of cells by theta oscillations is thought to globally coordinate the activity of cell assemblies across different structures, such as the hippocampus and neocortex. This coordination is likely required for optimal processing of sensory input during recognition and decision-making processes. In quadruple-area ensemble recordings from male rats engaged in a multisensory discrimination task, we investigated phase entrainment of cells by theta oscillations in areas along the corticohippocampal hierarchy: somatosensory barrel cortex (S1BF), secondary visual cortex (V2L), perirhinal cortex (PER), and dorsal hippocampus (dHC). Rats discriminated between two 3D objects presented in tactile-only, visual-only, or both tactile and visual modalities. During task engagement, S1BF, V2L, PER, and dHC LFP signals showed coherent theta-band activity. We found phase entrainment of single-cell spiking activity to locally recorded as well as hippocampal theta activity in S1BF, V2L, PER, and dHC. While phase entrainment of hippocampal spikes to local theta oscillations occurred during sustained epochs of task trials and was nonselective for behavior and modality, somatosensory and visual cortical cells were only phase entrained during stimulus presentation, mainly in their preferred modality (S1BF, tactile; V2L, visual), with subsets of cells selectively phase-entrained during cross-modal stimulus presentation (S1BF: visual; V2L: tactile). This effect could not be explained by modulations of firing rate or theta amplitude. Thus, hippocampal cells are phase entrained during prolonged epochs, while sensory and perirhinal neurons are selectively entrained during sensory stimulus presentation, providing a brief time window for coordination of activity

Phosphate glass fibrous scaffolds: tailoring of the properties and improvement of the bioactivity through the incorporation of mesoporous glasses

Introduction. Synthetic bone scaffolds are proposed as an alternative to the use of bone grafting technique for bone regeneration. Porous scaffold obtained from glass fibres randomly arranged into a mould shows an interconnected porosity generated by the free space between fibres and they do not need of any further material or processing step before sintering. In this work, a resorbable phosphate glass was selected for the fibre drawing and bioactive mesoporous glasses with different morphology and size were incorporated into the fibrous scaffold to combine the resorption property of the fibres with the bioactivity of the mesoporous powders. Materials and methods. Fibres of a TiO2-containing phosphate glass (TiPS2.5) were fabricated following the preform drawing approach as described elsewhere [1]. A dense silica-based bioactive glass (CEL2) [2] was produced by melt quenching as reference sample. Spherical micro-sized mesoporous glass based on SiO2-CaO system (SD_MBG) was produced by an aerosol-assisted spray-drying technique [3]. Cu-containing (85SiO2-13CaO-2CuO, % mol, referred as Cu_BGn2%) mesoporous glass nanoparticles were synthetized by an ultra-sound assisted sol-gel method to impart antibacterial properties. To fabricate the fibrous scaffolds, the selected powder and phosphate glass fibres, cut at precise length, were placed in a beaker containing 2 ml of ethanol. After ethanol evaporation, the powder/fibre mixture was randomly placed inside a zirconia cylindrical mould [4]. After the thermal treatment, the scaffolds were analyzed through micro-CT in order to investigate their inner structure. Furthermore, their ability to form hydroxyapatite was studied by soaking them in a simulated body fluid (SBF). The scaffold morphology before and after immersion in SBF was studied by FESEM. Results and discussion. FESEM micrographs show that CEL2 are not well incorporated into the fibre surface. On the contrary, SD-MBG (Figure 1.a, Figure 1.b and Figure 1.d) and Cu_BGn2% particles homogeneously cover the whole surface. Micro-CT analysis did not reveal the presence of powder agglomerates for all the observed scaffolds and showed a homogeneous porosity of 58 vol.% for CEL2/fibre scaffold, 53 vol.% for SD_MBG/scaffold (Figure 1.c) and 33% for Cu_BGn2%/scaffold. In CEL2/fibre scaffolds, glass particles were removed during soaking in SBF, leaving some pits on the fibre surface: FESEM analysis revealed few particles still anchored to the scaffold surface after 7 days. On the contrary, after 7 days in SBF, SD-MBG and Cu_BGn2% particles were clearly visible on the surface of the scaffolds and after 1 day of soaking in SBF, they appeared (Figure 2) fully covered with a HA layer, showing the typical "cauliflower-like" morphology. Conclusion. The incorporation of mesoporous bioactive glass powder in the phosphate glass fibrous scaffold resulted to be a very interesting strategy to impart multifunctional properties to the scaffold. These promising results encourage further investigation in order to fully exploit the ability of mesoporous particles to act as a system for smart release of therapeutic ions and drugs

Snare-Assisted Valve Positioning of Self-Expanding Valves for Transcatheter Aortic Valve Replacement

We describe 4 cases in which technical challenges were anticipated in delivering a self-expanding TAVR valve due to challenging aortic anatomy or a previous placed surgical aortic valve. An upfront snare strategy is described which facilitates valve centralization and atraumatic valve delivery. (Level of Difficulty: Advanced.

Understanding Selectivity of Mesoporous Silica-Grafted Diglycolamide-Type Ligands in the Solid-Phase Extraction of Rare Earths

Rare earth elements (REEs) and their compounds are essential for rapidly developing modern technologies. These materials are especially critical in the area of green/sustainable energy; however, only very high-purity fractions are appropriate for these applications. Yet, achieving efficient REE separation and purification in an economically and environmentally effective way remains a challenge. Moreover, current extraction technologies often generate large amounts of undesirable wastes. In that perspective, the development of selective, reusable, and extremely efficient sorbents is needed. Among numerous ligands used in the liquid-liquid extraction (LLE) process, the diglycolamide-based (DGA) ligands play a leading role. Although these ligands display notable extraction performance in the liquid phase, their extractive chemistry is not widely studied when such ligands are tethered to a solid support. A detailed understanding of the relationship between chemical structure and function (i.e., extraction selectivity) at the molecular level is still missing although it is a key factor for the development of advanced sorbents with tailored selectivity. Herein, a series of functionalized mesoporous silica (KIT-6) solid phases were investigated as sorbents for the selective extraction of REEs. To better understand the extraction behavior of these sorbents, different spectroscopic techniques (solid-state NMR, X-ray photoelectron spectroscopy, XPS, and Fourier transform infrared spectroscopy, FT-IR) were implemented. The obtained spectroscopic results provide useful insights into the chemical environment and reactivity of the chelating ligand anchored on the KIT-6 support. Furthermore, it can be suggested that depending on the extracted metal and/or structure of the ligand and its attachment to KIT-6, different functional groups (i.e., C= O, N-H, or silanols) act as the main adsorption centers and preferentially capture targeted elements, which in turn may be associated with the different selectivity of the synthesized sorbents. Thus, by determining how metals interact with different supports, we aim to better understand the solid-phase extraction process of hybrid (organo)silica sorbents and design better extraction materials

Towards heart tissue regeneration: a piezoelectric patch with smart nanocarriers for on-demand drug release

45% of death in Europe are ascribed to cardiac diseases and myocardial infarction (MI) weighs a large part of them. After an MI, a portion of the myocardium tissue is lost, substituted by fibrous tissue with minimal physiological functions: this can lead to severe heart dysfunction. Available therapies cannot successfully address the problem, therefore there is an urgent clinical need for new solutions. The Horizon Europe REBORN project (https://www.rebornproject.eu/project/) tackles this issue by designing a piezoelectric patch that can stimulate the restoration of healthy tissue by the piezoelectric fibre nanoarchitecture and on-demand drug release by nanocarriers (Fig. 1). The modulation of drug delivery can be triggered with different stimuli: within the REBORN project, ultrasounds will be used to control in-situ release. Among the various biofabrication techniques, electrospinning (ESP) is the most suitable to produce matrices with properties matching the ones of the cardiac extracellular matrix: aligned nanofibers with high interconnected porosity [1]. Furthermore, ESP provides high flexibility in terms of polymeric formulation that can be used, and it allows the incorporation of drug nanocarriers inside the fibres. The present work aims to exploit ESP with a rotating drum collector for the fabrication of polyvinylidene fluoride (PVDF) piezoelectric polymeric matrices with aligned fibres and the preliminary incorporation of mesoporous silica nanoparticles (MSN) as drug carriers. PVDF is a renowned piezoelectric biocompatible polymer largely used for electrospun devices for medical applications [2], and it was chosen to achieve electromechanical coupling with the myocardium. At first, non-toxic solvents to obtain PVDF spinnable solutions, acetone (ACE) and dimethyl sulfoxide (DMSO), were selected from the literature, to avoid possible cytotoxicity of the patch [3]. The effects of different formulations (PVDF concentration, ACE/DMSO ratio) and the ESP process parameters (voltage, flow rate, distance, drum speed) were investigated. The obtained membranes have been thoroughly characterized in terms of morphology, alignment, crystallinity, crystalline phases, mechanical properties, and wettability. By tuning the parameters, it was possible to obtain well-defined fibres, with a diameter of around 300 nm, and a good alignment. The piezoelectricity of PVDF depends on the amount of crystalline β phase, which was evaluated through FTIR spectroscopy along with the α and γ phases. The selected working conditions allow for obtaining high β phase content, about 94%. Furthermore, the overall crystallinity of the polymeric membranes, obtained by DSC, is also high, around 70%. The ESP process of PVDF is stable, allowing fibres deposition to last several hours, and to obtain various membrane thicknesses, from about 90 to 250 μm. The mechanical properties of the obtained membranes are comparable to the ones of other synthetic materials employed for cardiovascular surgery, with Young’s modulus of about 40 MPa and tensile strength of around 8.4 MPa, considering membranes thick about 100 μm. The contact angle is around 115°, as expected by a hydrophobic polymer. In preliminary trials for the incorporation of MSN, 5 %vol of MSNs was added to the PVDF solution. The nanoparticles were successfully embedded into the fibres, which showed smaller diameters with respect to fibres without MSNs due to the increased viscosity of the hybrid formulation. The PVDF+MSN membrane is a promising platform for the development of the REBORN patch and the treatment of heart failure due to MI. Future work will focus on the optimization of the ESP parameter and the investigation of drug release upon ultrasound stimulation. References [1] M.R. Gomes, F. Castelo Ferreira, P. Sanjuan-Alberte, Biomater. Adv. 137 (2022) 212808. [2] B. Azimi, M. Milazzo, A. Lazzeri, S. Berrettini, M.J. Uddin, Z. Qin, M.J. Buehler, S. Danti, Adv. Healthc. Mater. 9 (2020) 1901287. [3] J. Khao-iam, A. Salea, S. Chaipo, C. Putson, J. Phys. Conf. Ser. 2431 (2023) 012003

Multifunctional Copper-Containing Mesoporous Glass Nanoparticles as Antibacterial and Proangiogenic Agents for Chronic Wounds

The physiological wound healing process involves a cascade of events which could be affected by several factors resulting in chronic, non-healing wounds. The latter represent a great burden especially when bacterial biofilms are formed. The rise in antibiotic resistance amongst infectious microorganisms leads to the need of novel approaches to treat this clinical issue. In this context, the use of advanced biomaterials, which can enhance the physiological expression and secretion of the growth factors involved in the wound healing process, is gaining increasing attention as a robust and appealing alternative approach. Among them, mesoporous glasses are of particular interest due to their excellent textural properties and to the possibility of incorporating and releasing specific therapeutic species, such as metallic ions. One of the most attractive therapeutic ions is copper thanks to its proangiogenic and antibacterial effects. In this contribution, copper containing mesoporous glass nanoparticles were proposed as a multifunctional device to treat chronic wounds. The developed nanoparticles evidenced a very high specific surface area (740 m2/g), uniform pores of 4 nm and an almost total release of the therapeutic ion within 72 h of soaking. The produced nanoparticles were biocompatible and, when tested against Gram positive and Gram negative bacterial species, demonstrated antibacterial activity against both planktonic and biofilm bacteria in 2D cell monolayers, and in a 3D human model of infected skin. Their proangiogenic effect was tested with both the aortic ring and the chick chorioallantoic membrane assays and an increase in endothelial cell outgrowth at a concentration range between 30 and 300 ng/mL was shown. Overall, in this study biocompatible, multifunctional Cu-containing mesoporous glass nanoparticles were successfully produced and demonstrated to exert both antibacterial and proangiogenic effects

Omega results for cubic field counts via lower-order terms in the one-level density

In this paper, we obtain a precise formula for the one-level density of L-functions attached to non-Galois cubic Dedekind zeta functions. We find a secondary term which is unique to this context, in the sense that no lower-order term of this shape has appeared in previously studied families. The presence of this new term allows us to deduce an omega result for cubic field counting functions, under the assumption of the Generalised Riemann Hypothesis. We also investigate the associated L-functions Ratios Conjecture and find that it does not predict this new lower-order term. Taking into account the secondary term in Roberts???s conjecture, we refine the Ratios Conjecture to one which captures this new term. Finally, we show that any improvement in the exponent of the error term of the recent Bhargava???Taniguchi???Thorne cubic field counting estimate would imply that the best possible error term in the refined Ratios Conjecture is s ???????? (??????? 1/3 +????). This is in opposition with all previously studied families in which the expected error in the Ratios Conjecture prediction for the one-level density is ???????? (??????? 1/2 +????)

Ag modified mesoporous bioactive glass nanoparticles for enhanced antibacterial activity in 3D infected skin model

Bioactive glasses (BG) are versatile materials for various biomedical applications, including bone regeneration and wound healing, due to their bone bonding, antibacterial, osteogenic, and angiogenic properties. In this study, we aimed to enhance the antibacterial activity of SiO2-CaO mesoporous bioactive glass nanoparticles (MBGN) by incorporating silver (Ag) through a surface modification approach. The modified Ag-containing nanoparticles (Ag-MBGN) maintained spherical shape, mesoporous structure, high dispersity, and apatite-forming ability after the surface functionalization. The antibacterial activity of Ag-MBGN was assessed firstly using a planktonic bacteria model. Moreover, a 3D tissue-engineered infected skin model was used for the first time to evaluate the antibacterial activity of Ag-MBGN at the usage dose of 1 mg/mL. In the planktonic bacteria model, Ag-MBGN exhibited a significant antibacterial effect against both Pseudomonas aeruginosa and Staphylococcus aureus in comparison to non-engineered (Ag-free) MBGN and the blank control. Moreover, Ag-MBGN did not show cytotoxicity towards fibroblasts at the usage dose. However, in the 3D infected skin model, Ag-MBGN only demonstrated antibacterial activity against S. aureus whereas their antibacterial action against P. aeruginosa was inhibited. In conclusion, surface modification by Ag incorporation is a feasible approach to enhance the antibacterial activity of MBGN without significantly impacting their morphology, polydispersity, and apatite-forming ability. The prepared Ag-MBGN are attractive building blocks for the development of 3D antibacterial scaffolds for tissue engineering