17 research outputs found
Polysaccharide Layer-by-Layer Coating for Polyimide-Based Neural Interfaces
No full textImplantable flexible neural interfaces (IfNIs) are capable of directly modulating signals of the central and peripheral nervous system by stimulating or recording the action potential. Despite outstanding results in acute experiments on animals and humans, their long-term biocompatibility is hampered by the effects of foreign body reactions that worsen electrical performance and cause tissue damage. We report on the fabrication of a polysaccharide nanostructured thin film as a coating of polyimide (PI)-based IfNIs. The layer-by-layer technique was used to coat the PI surface due to its versatility and ease of manufacturing. Two different LbL deposition techniques were tested and compared: dip coating and spin coating. Morphological and physiochemical characterization showed the presence of a very smooth and nanostructured thin film coating on the PI surface that remarkably enhanced surface hydrophilicity with respect to the bare PI surface for both the deposition techniques. However, spin coating offered more control over the fabrication properties, with the possibility to tune the coating’s physiochemical and morphological properties. Overall, the proposed coating strategies allowed the deposition of a biocompatible nanostructured film onto the PI surface and could represent a valid tool to enhance long-term IfNI biocompatibility by improving tissue/electrode integration
Laboratory data - physical modelling of gravel bed rivers under unsteady flow conditions
No full textSediment transport and topography data from laboratory experiments under unsteady flow conditions.
Data supporting the manuscript:
Redolfi, M., Bertoldi, W., Tubino, M., & Welber, M. (2018). Bed load variability and morphology of gravel bed rivers
subject to unsteady flow: A laboratory investigation. Water Resources Research, 54, 842–862. https://doi.org/
10.1002/2017WR021143
Details about the physical model and the experimental procedure can be found in the paper.For further information please contact the corresponding author at [email protected]
Evaluationof theefficiencyofbiologicalnematicides Formulated with Pochoniachlamydosporia(PC-10) and Purpureocilliumlilacinum(Pae10) inmanagement of Meloidogyneincognita and M.javanica in thetobacco culture
No full textA cultura do tabaco acumula perdas consideráveis em decorrência do ataque de nematoides das galhas e a constante busca de alternativas para controle desta praga constitui-se numa preocupação mundial. Com o intuito de avaliar a eficiência de dois agentes de controle biológico formulados à base dePochoniachlamydosporia (Pc-10) e Purpureocillium lilacinum (Pae 10)no manejo de Meloidogyneincognitae M.javanicaem mudas de tabaco, foram realizados os seguintesexperimentos: (1)in vitro, no qualse testou a compatibilidade comos fungicidasà base de óxido cuproso, de metalaxil M + mancozebe ou de iprodiona, e a compatibilidade entre eles; (2) em casa de vegetação, para analisaro efeito daaplicação deproduto formulado com P. chlamydosporia (Pc-10)e P. lilacinum (Pae 10)aos 5, 10, 15 e 20 dias antesdo transplantio, e(3) em campopara medir a eficiência de uma ou duas aplicações de produto a base deP. chlamydosporia. Os resultados obtidos in vitro indicaram que os fungos P. chlamydosporia eP. lilacinumnãointeragem entre si, e que os fungicidas testados não afetaramo desenvolvimento destes. Os experimentos em casa de vegetação indicaram quea aplicação do produto a base de P. lilacinumreduziu 56 e 59% na média da massa e número de ovos aos 5 e 15 dias, respectivamente, após o transplantio. Ao passo que, P. chlamydosporia apresentou redução na média no número de ovos e na massa de ovos de M. javanica em todas as épocas testadas.Já em campo, o produto formulado com P. chlamydosporia, em uma aplicação, em solo arenoso, reduziu o número de ovos e índice de galhas, porém, não aumentou a produtividade e qualidade do tabaco nas duas áreas avaliadas. Conclui-se, portanto, que o nematicida a base de P. chlamydosporia, é um produto eficiente na redução de M. incogita and M. javanica.Nematode attack results into considerable cumulative losses in the tobacco crop, so the constant search for alternatives to manage this pest constitutes a global concern. In order to evaluate the efficiency of two biological control agents formulated based on Pochonia chlamydosporia (Pc-10) and Purpureocillium lilacinum (Pae 10) in management of Meloidogyneincognita and M. javanica in the tobacco crop, the following experiments were performed (1) in vitro, in order to evaluate compatibility with cuprous oxide, metalaxyl M + mancozeb or iprodione fungicides and also compatibility among them; (2) in greenhouse, to analyze the effect of P. chlamydosporia and P. lilacinum at 5, 10, 15 and 20 days before transplanting, and (3) in the field to measure the effectiveness of one and two applications of P. chlamydosporia. Results in vitro showed that there is no interaction between P. chlamydosporia and P. lilacinum, and their developments were not affected by the fungicides tested. The experiments performed in the greenhouse showed a reduction of 56 and 59%in the mass and number of eggs at 5 and 15 days after application, respectively,when the nematicide formulated with P. lilacinumwas used. On the other side, the product formulated with P. chlamydosporia reduced the number and mass of eggs ofM. javanica, regardless the time of application. Regarding the field results, the nematicide formulated with P. chlamydosporia, in sandy soil and one application, reduced the number and index of eggs, however, with no increase of tobacco yield for both areas. We conclude the nematicide formulated with P. chlamydosporia is an effective component of management ofM. incognita andM. javanic
A Novel Fabrication Strategy for Fully-Polymeric Cuff Electrodes
No full textAmong the multitude of nerves constituting the autonomic nervous system, the vagus nerve (VN) emerges as the longest and most relevant nerve. It enables bidirectional communication between brain and body organs, for it is involved in the regulation of autonomic, cardiovascular, respiratory, gastrointestinal, immune, and endocrine systems. Given the multitude of organs, including the larynx, pharynx, heart, lungs, and gastrointestinal ones, linked to the VN through afferent and efferent pathways, a broad spectrum of pathologies can be associated with its dysfunction. Simultaneously, disorders affecting organs either directly or indirectly innervated by the VN can be targeted or mitigated through the strategic modulation of this nerve's activity. Electrical stimulation of the VN is an approved therapy for refractory epilepsy, treatment-resistant depression, obesity, and stroke rehabilitation, and it has also been tested, among other diseases, in heart failure, inflammatory bowel disease, and rheumatoid arthritis. Currently, though, systems for Vagus Nerve Stimulation (VNS) suffer from low specificity in fiber stimulation, which leads to side effects such as cough, throat pain, voice alteration, and dyspnea due to the unwanted activation of off-target motor efferent fibers innervating throat muscles. Therefore, innovative neural interfaces allowing for a more targeted stimulation of the nerve fibers are of particular interest in this field. In this regard, the proven organotopy of the vagus nerve makes multi-contact cuff electrodes particularly effective in providing a radially and functionally selective stimulation of this nerve. Besides, this kind of interface benefits from a reduced foreign body reaction, due to its low invasiveness, further diminished in the case of a well-designed anchoring strategy and properly selected soft and biocompatible materials.
The aim of this thesis was to establish a robust and low-cost fabrication protocol for manufacturing fully- polymeric multi-contact cuff electrodes. Specifically, electrodes were intended to be made entirely of Polydimethylsiloxane (PDMS) and a 5 wt% solution of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) in a mixture of deionized water and dimethyl sulfoxide (DMSO) in an 80:20 ratio. The rationale behind the fully-polymeric approach was to avoid the metal-related issues of both the mechanical tissue-electrode mismatch, causing harsh Foreign Body Reactions (FBRs) and hence hindering long-term applications, and the potential triggering of redox processes, leading to the in situ release of metal ions. The initial premise was to create two layers of PDMS, each approximately 100 μm thick, with conductive PEDOT:PSS traces encapsulated in between. One of these layers, the one in contact with the nerve, had to feature some strategically placed active site holes to allow exposure of the conductive material. The electrode dimension was tailored to the swine VN (approximately 3 mm in diameter). Moreover, an innovative strategy for securely fastening the flat cuff electrode once wrapped around the nerve was devised. This strategy involved equipping one side of the electrode with a belt loop-shaped hole while incorporating a locking geometry on the opposite end.
To this extent, an innovative fabrication strategy was developed after testing an extrusion printing approach. The specifics of this fabrication strategy are not disclosed as they are the subject of a patent submission. With our methodology, an electrode prototype was manufactured and subjected to optical and electrochemical testing. The electrochemical tests involved Electrochemical Impedance Spectroscopy (EIS) and Cyclic Voltammetry (CV).
The produced electrode featured conductive traces and active sites with an average width of 206 ± 26 μm, and 293 ± 25 μm, respectively, and fitted a 2740 µm diameter circle when wrapped and secured with the custom locking mechanism. The EIS resulted in the assessment of an average active site impedance at 1 kHz of 4.28 ± 2.93 kΩ, excluding an outlier active site. The CV enabled the calculation of the cathodic charge storage capacity, averaging 6022 ± 1208 mC/cm^2. Furthermore, the absence of peaks in the CV plots of the measured cathodic current over the normalized potential, aside from the broad anodic and cathodic ones at the ends of the scanned range, was considered an indicator of electrochemical stability and the absence of potentially detrimental redox processes
Sviluppo e caratterizzazione di un rivestimento per interfacce intraneurali fabbricato con tecnica layer by layer
No full textL’obiettivo della tesi è lo sviluppo di un rivestimento biocompatibile per interfacce neurali invasive rivolte al sistema nervoso periferico. Allo stato attuale, il successo delle interfacce intraneurali è limitato dalla formazione di un tessuto fibrotico attorno all'impianto causata dalla risposta al corpo estraneo, dunque dalla sua limitata biocompatibilità. Questo progetto di tesi mira a migliorare la compatibilità biologica e funzionale del materiale di supporto meccanico dell’elettrodo, con lo scopo di garantire la stabilità e l’affidabilità delle interfacce neurali in applicazioni croniche. L’idea è quella di realizzare un coating biocompatibile per far sì che il materiale di rivestimento dell’elettrodo non sia a diretto contatto con il tessuto neurale, ma abbia un‘interfaccia di materiali idrofilici con caratteristiche meccaniche, fisico-chimiche molto più simili a quelle del nervo. Pellicole multistrato formulate mediante deposizione layer by layer si sono rivelate essere un approccio promettente per la creazione di substrati aventi proprietà superficiali flessibili che possono modulare il comportamento cellulare. In questo lavoro è stato proposto un rivestimento polimerico su scala nanometrica mediante funzionalizzazione superficiale della poliimmide sfruttando la versatilità della tecnica layer by layer. Questo rivestimento è composto da multilayers di chitosano/alginato depositati mediante due diverse tecniche di deposizione: spin coating e dip coating. Polimeri di origine naturale sono stati selezionati per le proprietà di citocompatibilità, biodegradabilità, presenza di siti di riconoscimento cellulare e somiglianza naturale con i tessuti biologici. I nanofilm multilayers sono stati caratterizzati per verificare la presenza del rivestimento in chitosano e alginato sulla superficie di PI, controllando lo spessore dei layers e la bagnabilità della superficie. Ulteriore prova della presenza dello strato polielettrolita è stata verificata mediante analisi FTIR
Polysaccharide Layer-by-Layer Coating for Polyimide-Based Neural Interfaces
No full textImplantable flexible neural interfaces (IfNIs) are capable of directly modulating signals of the central and peripheral nervous system by stimulating or recording the action potential. Despite outstanding results in acute experiments on animals and humans, their long-term biocompatibility is hampered by the effects of foreign body reactions that worsen electrical performance and cause tissue damage. We report on the fabrication of a polysaccharide nanostructured thin film as a coating of polyimide (PI)-based IfNIs. The layer-by-layer technique was used to coat the PI surface due to its versatility and ease of manufacturing. Two different LbL deposition techniques were tested and compared: dip coating and spin coating. Morphological and physiochemical characterization showed the presence of a very smooth and nanostructured thin film coating on the PI surface that remarkably enhanced surface hydrophilicity with respect to the bare PI surface for both the deposition techniques. However, spin coating offered more control over the fabrication properties, with the possibility to tune the coating's physiochemical and morphological properties. Overall, the proposed coating strategies allowed the deposition of a biocompatible nanostructured film onto the PI surface and could represent a valid tool to enhance long-term IfNI biocompatibility by improving tissue/electrode integration.TN
Circuit formation and function in the olfactory bulb of mice with reduced spontaneous afferent activity
No full textThe type of neuronal activity required for circuit development is a matter of significant debate. We addressed this issue by analyzing the topographic organization of the olfactory bulb in transgenic mice engineered to have very little afferent spontaneous activity due to the overexpression of the inwardly rectifying potassium channel Kir2.1 in the olfactory sensory neurons (Kir2.1 mice). In these conditions, the topography of the olfactory bulb was unrefined. Odor-evoked responses were readily recorded in glomeruli with reduced spontaneous afferent activity, although the functional maps were coarser than in controls and contributed to altered olfactory discrimination behavior. In addition, overexpression of Kir2.1 in adults induced a regression of the already refined connectivity to an immature (i.e., coarser) status. Our data suggest that spontaneous activity plays a critical role not only in the development but also in the maintenance of the topography of the olfactory bulb and in sensory information processin
Axonal Odorant Receptors Mediate Axon Targeting
No full textIn mammals, odorant receptors not only detect odors but also define the target in the olfactory bulb, where sensory neurons project to give rise to the sensory map. The odorant receptor is expressed at the cilia, where it binds odorants, and at the axon terminal. The mechanism of activation and function of the odorant receptor at the axon terminal is, however, still unknown. Here, we identify phosphatidylethanolamine-binding protein 1 as a putative ligand that activates the odorant receptor at the axon terminal and affects the turning behavior of sensory axons. Genetic ablation of phosphatidylethanolamine-binding protein 1 in mice results in a strongly disturbed olfactory sensory map. Our data suggest that the odorant receptor at the axon terminal of olfactory neurons acts as an axon guidance cue that responds to molecules originating in the olfactory bulb. The dual function of the odorant receptor links specificity of odor perception and axon targeting.sponsorship: We are grateful to J.A. Gogos for advice and for generously providing the P2GFP mice. We thank Evan Keller for PEPB1-/- mice and M. Rosner for pGEX2T-rat-RKIPcDNA. We thank C. Fecchio and G. Lolli for helping with chromatography experiments. We thank Dorien Vandael and Frank Vernaillen for helping with the clearing experiments. We are grateful to Kevin Zhu and Priyanka Meesa for their contribution in editing the manuscript. We thank all members of Lodovichi lab for support and insightful discussion. This work was supported by Armenise-Harvard Foundation CDA (USA), Telethon Foundation (Italy) GGP13187, GGP 11116 and GGP19281, Cariparo Foundation grant (Italy), and MIUR-CNR Nanomax (Italy) to C.L. (Armenise-Harvard Foundation CDA (USA), Telethon Foundation (Italy)|GGP13187, Telethon Foundation (Italy)|GGP 11116, Telethon Foundation (Italy)|GGP19281, Cariparo Foundation grant (Italy), MIUR-CNR Nanomax (Italy), MRC|UKDRI-1004)status: Publishe
Impacts of Ta Buffer Layer and Cu-Ge-Te Composition on the Reliability of GeSe-Based CBRAM
No full textsponsorship: This work was supported by imec's Core Partner Industrial Affiliation Program on Emerging Memories. The review of this article was arranged by Editor P. Du. (Corresponding author: Janaki Radhakrishnan.) (imec's Core Partner Industrial Affiliation Program on Emerging Memories)status: Publishe
Impact of tungsten oxidation conditions on the performance of Al2O3/WOx-based CBRAM devices
No full textIn this paper, we assess the impact of different W oxidation conditions on the electrical performance of Cu/AIl(2)O(3)/WON-based CBRAM devices. While HR-TEM characterization carried out on samples with three different oxidation conditions reveals that WON is always in the crystalline phase in our oxidation temperature range, higher oxidation temperature leads to denser and thicker oxides. By performing DC and AC electrical characterization, we demonstrate that a careful engineering of the W oxidation conditions enables to boost the performance of these devices. In particular, we prove that a trade-off between density and thickness must be pursued in order to enlarge the memory window and extend the endurance lifetime with short (10 ns) pulses. (C) 2017 Published by Elsevier B.V.China Scholarship Council [201506010181]SCI(E)ARTICLE56-5917
