Academic literature on the topic 'Electrode – tool'

Electrochemical discharge machining (ECDM) is an emerging method for developing micro-channels in conductive or non-conductive materials. In order to machine the materials, it uses a combination of chemical and thermal energy. The tool electrode’s arrangement is crucial for channeling these energies from the tool electrode to the work material. As a consequence, tool electrode optimization and analysis are crucial for efficiently utilizing energies during ECDM and ensuring machining accuracy. The main motive of this study is to experimentally investigate the influence of different electrode materials, namely titanium alloy (TC4), stainless steel (SS304), brass, and copper–tungsten (CuW) alloys (W70Cu30, W80Cu20, W90Cu10), on electrodes’ electrical properties, and to select an appropriate electrode in the ECDM process. The material removal rate (MRR), electrode wear ratio (EWR), overcut (OC), and surface defects are the measurements considered. The electrical conductivity and thermal conductivity of electrodes have been identified as analytical issues for optimal machining efficiency. Moreover, electrical conductivity has been shown to influence the MRR, whereas thermal conductivity has a greater impact on the EWR, as characterized by TC4, SS304, brass, and W80Cu20 electrodes. After that, comparison experiments with three CuW electrodes (W70Cu30, W80Cu20, and W90Cu10) are carried out, with the W70Cu30 electrode appearing to be the best in terms of the ECDM process. After reviewing the research outcomes, it was determined that the W70Cu30 electrode fits best in the ECDM process, with a 70 μg/s MRR, 8.1% EWR, and 0.05 mm OC. Therefore, the W70Cu30 electrode is discovered to have the best operational efficiency and productivity with performance measures in ECDM out of the six electrodes.

The utilization of epidural electrodes in the preoperative evaluation of intractable epilepsy is a valuable but underrepresented tool. In recent years, we have adapted the use of cylindrical epidural 1-contact electrodes (1-CE) instead of Peg electrodes. 1-CEs are more versatile since their explantation is a possible bedside procedure. Here we report our experience with 1-CEs as well as associated technical nuances. This retrospective analysis included 56 patients with intractable epilepsy who underwent epidural electrode placement for presurgical evaluation at the Department of Neurosurgery at the Charité University Hospital from September 2011 to July 2021. The median age at surgery was 36.3 years (range: 18–87), with 30 (53.6%) female and 26 (46.4%) male patients. Overall, 507 electrodes were implanted: 93 Fo electrodes, 33 depth electrodes, and 381 epidural electrodes, with a mean total surgical time of 100.5 ± 38 min and 11.8 ± 5 min per electrode. There was a total number of 24 complications in 21 patients (8 Fo electrode dislocations, 6 CSF leaks, 6 epidural electrode dislocations or malfunction, 3 wound infections, and 2 hemorrhages); 11 of these required revision surgery. The relative electrode complication rates were 3/222 (1.4%) in Peg electrodes and 3/159 (1.9%) in 1-CE. In summary, epidural recording via 1-CE is technically feasible, harbours an acceptable complication rate, and adequately replaces Peg electrodes.

The paper presents the results of experimental research on the wear mechanism of the tool-electrode as a result of machining metal materials by applying electric discharges in pulse. It examines several phenomena noticed on the tool - electrode surface, exactly, the oxide layer formation and the modification of the micro geometry of the tungsten tool electrode surface. The paper presents the experimental results on the behavior of the tool electrode made of stainless steel after the metal parts have been machined. It also presents the phases of mass transfer in the gap between electrodes.

Electro discharge machining is an energy based method that can cause fast electrode wear and dimensional errors. This study aimed to identify the optimum process parameters for processing 1.2767 steel using copper-based electrodes. The Taguchi optimization approach was used, and 18 pieces of 1.2767 steel were prepared for the experiments. The electrodes used were CuCoNiBe and CuNi2SiCr, and the electrode surfaces were sanded and polished before processing. The results showed that the CuNi2SiCr electrode produced the lowest overcut value of 0.07 mm, while the CuCoNiBe electrode had the highest observed overcut value of 0.320 mm. The discharge level had the most significant impact on overcut, while the type of electrode had the least. The optimal parameters for the CuNi2SiCr electrode were 12 A discharge current, 50 µs pulse duration, and 800 µs pulse off time. The processing under ideal conditions resulted in an overcut measurement value of 0.05 mm.

Aiming at the problem of obvious tool length wear and side wear in the small hole processing of EDM, the nickel-coated composite electrode and diamond-nickel-coated composite electrode were prepared by chemical composite coating using brass, copper, molybdenum, and copper-tungsten alloy materials as the matrix material. Comparative experiments of EDM small hole machining using composite tools were carried out on die steel. The effects of nickel-coated composite electrode and diamond-nickel-coated composite electrode on tool length wear, tool side wear, and tool shape change were analyzed. The results show that the diamond-nickel-coated composite electrode can effectively reduce both the length wear and side wear of the electrodes.

A new method for on-line fabrication of micro tool-electrodes is presented in this paper. The method is base on the machining mechanism of electrochemical micromachining. By exchanging the polarities of the tool-electrodes and workpiece repeatedly, micro tool-electrode appropriate for electrochemical micromachining can be obtained through mutual machining. Because the processes are carried out on-line, the position error and clamp error caused by twice-clamp of tool-electrodes can be avoided, and the machining precision can be improved greatly. This method will be very important to electrochemical generating micromachining. Experiments are carried out, and a tool-electrode with the pinpoint of 20μm can be machined stably.

The paper deals with the wear of tool electrodes for Die Sinking EDM. In the experiment were used the electrodes of copper and graphite. The workpiece material was steel EN43CrMo4. For the assessment the effects of each parameter was used the statistical method Design of Experiments (DOE). Assessed input factors were the peak current, pulse on-time, pulse off-time, and the electrode material. The result of the effects of each input factors was tool electrode wear. For calculating the relative wear of electrodes was used the percentage of the ratio of the electrode and the workpiece weight. The results show that the expression of the relative wear in practice can be described as a method unusable due to the absorption of the graphite electrode used in the experiment.

The present experimental study has been focused to evaluate surface characteristics of cryogenically-treated (shallow/deep) tool-electrodes using powder mixed electric discharge machining. Due to the continuously growing demand of complex and precise parts, tool-electrodes have its own importance, because quality of the machined parts depends upon the surface quality of electrode. On the analogy, eighteen experiments were performed based on L18orthogonal array of Taguchi’s methodology, which consist eight input parameters. Analysis of variance (ANOVA) was employed to designate the level of significance of input parameters. Electrode material has maximum influence followed by the current and pulse on-time on electrode finish. The combination of optimum factor’s level of identified parameters was determined using Taguchi’s technique for single response. Confirmation experiments were conducted using suggested optimal parameters with its respective level to minimize the tool-electrode surface roughness. Surface characteristics of tool-electrodes were analyzed using Scanning Electron Microscope (SEM) and Energy Dispersive Spectrograph (EDS) followed by X-ray diffraction (XRD) on selected samples. The results exposed that significant material transfer from workpiece and powder mixed dielectric fluid in compound form on the tool surface.

Electric discharge machining (EDM) widely used mostly in the tool and die industry and the material normally used as electrode are copper, tungsten, graphite, copper tungsten and copper chromium alloys. In the present work, Electric discharge machining was carried on H-13 workpiece using powder metallurgy electrodes of copper chromium (CuCr) and conventional copper electrode. The input parameters selected in the study were current, voltage, duty cycle and retract distance. The output parameters were material removal rate, tool wear rate, surface roughness and overcut. Experimental results show that CuCr powder metallurgy electrode gives best results for MRR. Also CuCr powder metallurgy electrodes gives better results for overcut as compare to conventional copper electrode. It has been seen that electrode type is significant factor for all output parameters.

Micro electro discharge machining is an important unconventional metal micromachining technology. The performance of micro EDM depends on the combination of the tool and work materials used. In the absence of a comprehensive theoretical model to predict the effect of electrode materials on the performance of EDM, experimental investigations as described in this paper become useful. The work materials studied include ferrous, non-ferrous and exotic material (XW42, Ti6Al4V, WC) and the tool electrode materials include the commonly used EDM tool materials namely tungsten, copper and graphite. It is found that in the microgroove machining by micro EDM using foil electrodes, graphite consistently provides higher material removal rate than tungsten and copper tool electrodes and hence it is useful for the rough machining. On the other hand tungsten tool electrode is preferable for finish machining as it provides the least surface roughness.

Diplomová práce se zabývá problematikou volby grafitového materiálu využívaného pro výrobu nástrojových elektrod při elektroerozivní obrábění. Práce je rozdělena do třech částí. Teoretická rešerše nekonvenční technologie elektroerozivního obrábění vypracovaná dle uvedených zdrojů se nachází v první části práce. Dále je v práci proveden cenový průzkum EDM grafitových materiálů nabízených v České republice a na Slovensku. Čtyři odlišné stupně kvality grafitu (od stávajícího dodavatele firmy GAMARTIS TRADE s.r.o.) a jeden měděný materiál byly podrobeny experimentu, jehož účelem bylo zjištění závislosti mezi kvalitou grafitového materiálu (cena) a přesností vyhloubené kavity, opotřebením nástrojové elektrody, časem obrábění nebo také drsností povrchu.

This thesis deals with technology of electric discharge machining with emphasis on application of the principle of material removal on wire cut electric discharge machine. The main part is concentrated on wire cut electric discharge machining in terms of a small tool making shop. The goal of the thesis is to create a wire cut electric discharge machining workplace in the company with a focus on the production of cutting tools. The thesis defines requirements for each component of cutting tools and strategies for their machining. Machining of model part and subsequent technical - economic evaluation is included in the final part.

Controlling processes by electrochemical means is increasingly attracting the attention of organic and polymer chemists. Electrochemistry provides tunable parameters without requiring the addition of external compounds, often increasing system tolerance to impurities, thus facilitating reaction handling and switching among different stages. In the last decades, the main interest in polymer chemistry concerned the preparation of predetermined macromolecular architectures. Atom transfer radical polymerization (ATRP) is the most powerful and versatile method to build well-defined polymers, with narrow molecular-weight distribution and excellent retention of chain-end functionalities. ATRP is based on the reversible deactivation of propagating radicals, such as to extend the lifetime of polymer chains. Radical concentration in solution is always very low, ultimately minimizing their probability of terminating. The activation-deactivation equilibrium is generally governed by a metal catalyst, composed by copper and a polydentate amine ligand. The active form of the catalyst, [CuIL]+, generates radicals by reductive cleavage of the C–X bond in the alkyl halide initiator, RX. As a consequence of the electron transfer and the concurrent atom transfer, the deactivator [X–CuIIL]+ is formed. Generated radicals add to few monomer molecules (i.e. propagation reaction), then they are reverted to their dormant state by reacting with [X–CuIIL]+. Importantly, RX initiators should be highly reactive, as to ensure the simultaneous growth of all polymer chains, thereby targeting pre-determined molecular weights. Chain-end functionalities are preserved during the polymerization, thus enabling several post-polymerization processes and the building of copolymers with various compositions and topologies. The aim of this thesis is to affirm electrochemical tools as a primary, effective and accessible source for ATRP triggering and mechanistic analysis. Less than 20 years ago, electrochemistry was involved for the first time in ATRP, when standard reduction potentials of some common catalysts were determined by cyclic voltammetry (CV) and correlated to their catalytic performances. Since then, CV is a well-established technique to study the redox properties of ATRP catalysts and the relative affinity of CuI and CuII species for halide ions, hence predicting their activity in the polymerization. Moreover, many electrochemical procedures were arranged for the precise measurement of the activation rate constant, kact, which concerns the reaction between [CuIL]+ and RX. kact values spanning over a range of 12 orders of magnitude were measured with different techniques, in many environments. Among these techniques, the use of a rotating disk electrode allowed a fast, easy and highly reproducible measurement. This instrument was further exploited in this thesis work to set up a facile electrochemical procedure for the determination of the thermodynamic equilibrium constant of ATRP, KATRP. Essentially, the reaction between CuI species and RX was followed as for kact determination, but in the absence of a radical scavenger that had been used to kinetically isolate the activation step. The interplay between activation, deactivation and radical termination was monitored, and KATRP was obtained by elaborating the electrochemical response through an equation proposed by Fischer and recently slightly modified. The method was applied to different Cu catalysts, initiators, solvent/monomer combinations and temperatures, observing some trends in accordance with general ATRP understanding. Both kact and KATRP must be measured in the absence of halide ions, which strongly affect the speciation of CuI. Indeed, the amount of active [CuIL]+ is reduced by the formation of various halogenated CuI species, thus slowing down the reaction with RX. However, the drop in the rate of CuI consumption in the presence of different C_(X^- ) was used to estimate the association constant of X− to [CuIL]+ (i.e. CuI halidophilicity constant, K_X^I). A procedure to measure K_X^I from K_ATRP^app, obtained under various C_(X^- ), was reported and verified for an independently determined K_X^I value. Electrochemistry is not only used to study ATRP mechanism, but also to effectively trigger the polymerization process. In fact, an applied current or potential is used to re-generate CuI from [X–CuIIL]+, which accumulates in solution because of termination events. Electrochemically mediated ATRP (eATRP) uses electrons as a reducing agent, thus it is free of by-products and allows to start from a minimum amount of air-stable CuII, which is reduced in situ. Nonetheless, the traditional eATRP setup required a potentiostat and expensive Platinum electrodes. During my Ph.D., I tried to simplify the setup as to make eATRP a cost-effective and scalable technique. Various inexpensive and easily functionalizable materials were successfully used as cathodes for eATRP in both organic and aqueous media. These working electrodes allowed well-controlled polymerizations even under galvanostatic conditions (i.e. constant current steps), which permitted the use of two, instead of three electrodes, and the replacement of the potentiostat with a common current generator. Furthermore, these cathodes were coupled to a sacrificial Aluminum anode in a completely Pt-free setup. Finally, these materials did not release metal ions in solution during the polymerization, and their morphology was not modified, thus they could be re-used in consecutive experiments. One important feature of eATRP and ATRP in general is their high versatility. Actually, various types of monomers are suitable for these techniques. Instead, controlled polymerization of acidic monomers via ATRP was considered impossible until very recently. In 2016, Fantin at al. proved that growing chains of poly(methacrylic acid) in ATRP were affected by a cyclization reaction with loss of C-X functionalities, i.e. termination. Suitable conditions to overcome this issue were proposed and successful eATRPs of methacrylic acid were reported. This important achievement was extended to acrylic acid (AA), which is a biocompatible, largely used monomer. In this thesis, it is proved that AA polymerization was hampered by the same cyclization side reaction during eATRP. Indeed, some conditions that were suitable for methacrylic acid were successfully adapted to eATRP of AA. i) Chloride ions replaced bromides, and ii) polymerization rate was enhanced by using a cathode with large surface area, applying a strongly negative potential, compared to Eѳ of the catalyst, and optimizing the amount and the nature of other reactants. One way to broaden the applicability of ATRP is to design new ligands able to convey particular features to Cu catalysts. Herein, 4 new ligands are presented, in which the skeleton of the traditionally used tris(2-methylpyridyl)amine (TPMA) was modified with m-functionalized phenyl substituents. Electrochemical characterizations of Cu complexes with these ligands allowed to predict a lower activity toward RX, compared to parent TPMA, which was proved by kact determination. Nevertheless, these complexes were used to catalyze well-controlled eATRPs of methyl methacrylate in DMF, and oligo (ethyleneoxide) methyl ether methacrylate and methacrylic acid in water. Despite the low activity, these compounds were very stable even at acidic pH and can be used to tune the polymerization in extremely reactive system. The versatility of ATRP is also reflected by the application in different environments. Ionic liquids for example are attracting great interest as green solvents for polymerizations. In 1-butyl-3-methylimidazolium trifluoromethanesulfonate, the redox properties of common ATRP catalysts and initiators were investigated by CV, whereas kinetic studies were performed via rotating disk electrode. This work proved that the behavior of Cu complexes and RX in ILs is similar to the one observed in traditional organic solvents. Therefore, ILs are suitable media for controlled polymerizations, and particularly they should be applied as solvent for eATRP because they are sufficiently conductive without added supporting electrolytes. Dispersed media represent another eco-friendly environment for polymerizations. Although many industrial processes are based on (mini)emulsion systems, the vast majority of literature reports on ATRP concerns experiments in homogeneous solutions. ATRP in miniemulsion required the design of super hydrophobic catalysts that remained confined into hydrophobic droplets, whereby tuning the polymerization. During my Ph.D., I spent six months as a visiting student at Carnegie Mellon University, in the laboratory of Prof. Matyjaszewski, who discovered ATRP in 1995. There, I had the opportunity to work on ATRP in miniemulsion and emulsion. A new catalytic system was arranged, and effectively applied to eATRP and activators re-generated by electron transfer (ARGET) ATRP, in which a reducing agent is added to continuously re-generate CuI species. Common hydrophilic catalysts were combined to inexpensive surfactants to form ion pairs able to enter the monomer droplets and catalyze the process. Electrochemical and spectrochemical characterizations proved the interactions between the compounds and defined the different contributions from ion-pair and interfacial catalysis. Block copolymers, polymer stars and brushes were easily synthetized with this approach. Moreover, residual copper in precipitated polymers was very low, even < 1 ppm, thus avoiding the need of further purifications. The system was then adapted to emulsion ARGET-ATRP, taking advantage of the water-solubility of the catalyst, which is a requirement of emulsion polymerizations, where the process should occur in the aqueous phase. By using suitable hydrophilic initiators and finely tuning the stirring rate and the pre-emulsification procedure, well controlled ab initio emulsion ARGET-ATRPs were obtained, even with low surfactant amounts.<br>La possibilità di controllare processi per via elettrochimica riveste crescente attenzione nel mondo della chimica organica e della sintesi di polimeri. L’elettrochimica offre diversi parametri per intervenire sulle proprietà dei sistemi in oggetto, senza introdurre altri agenti chimici e spesso aumentando la tolleranza del sistema verso le impurezze. Di conseguenza la gestione del processo e il passaggio tra diversi stadi risultano facilitati. Negli ultimi dieci anni, il principale interesse nel campo della sintesi polimerica riguarda la preparazione di macromolecole con architetture predeterminate. La polimerizzazione radicalica per trasferimento di atomo (ATRP) è la tecnica più versatile e affermata per la costruzione di polimeri ben definiti, con stretta distribuzione di pesi molecolari ed eccellente ritenzione di funzionalità di fine catena. L’ATRP si basa sulla disattivazione reversibile dei radicali propaganti, in modo da allungare il tempo di vita delle catene in crescita. La concentrazione di radicali in soluzione rimane sempre molto bassa, portando così a minimizzare la probabilità dei radicali stessi di essere soggetti a terminazione. L’equilibrio di attivazione-disattivazione è generalmente governato da un catalizzatore metallico, composto da un centro di rame e un legante amminico polidentato. Nella sua forma attiva, [CuIL]+, il catalizzatore genera radicali per rottura riduttiva del legame C–X nell’alogenuro alchilico, RX, utilizzato come iniziatore. La specie disattivante [X–CuIIL]+ si forma in seguito al trasferimento elettronico e atomico che avvengono in contemporanea. I radicali generati riescono ad addizionare solo poche molecole di monomero (reazione di propagazione), prima di essere riconvertiti al loro stato dormiente tramite reazione con [X–CuIIL]+. In ATRP è importante che gli iniziatori siano altamente reattivi, in modo da garantire la crescita simultanea di tutte le catene e quindi poter ottenere pesi molecolari predeterminati. Le funzionalità di fine catena non vengono intaccate durante la polimerizzazione e questo permette di sottoporre il polimero a processi di post-polimerizzazione e di costruire copolimeri con varie composizioni e topologie. Lo scopo di questa tesi di dottorato è quello di affermare l’elettrochimica come fondamentale, accessibile ed efficace risorsa per l’analisi meccanicistica dei processi di ATRP e anche per condurre questo tipo di polimerizzazioni. Meno di venti anni fa, studi elettrochimici furono per la prima volta utilizzati in ATRP: i potenziali standard di riduzione di alcuni catalizzatori comunemente usati furono determinati tramite voltammetria ciclica (CV) e correlati alle performances catalitiche di questi composti. Da allora, la CV è la tecnica per eccellenza per lo studio delle proprietà redox dei catalizzatori per ATRP, nonché per la determinazione delle affinità relative delle specie di CuI e CuII per gli ioni alogenuro, quindi per predire l’attività dei complessi nella polimerizzazione. Inoltre, diverse procedure elettrochimiche sono state messe a punto per misurare con elevata precisione la costante cinetica di attivazione, kact, che riguarda quindi la reazione tra [CuIL]+ e RX. Valori di kact che coprono 12 ordini di grandezza sono stati misurati con diverse tecniche, in vari ambienti. Tra le suddette tecniche, l’utilizzo di un elettrodo a disco rotante (RDE) consente misure rapide, facilmente realizzabili e altamente riproducibili. Il RDE è stato usato in questo lavoro di tesi per definire una semplice procedura elettrochimica per la determinazione della costante termodinamica di equilibrio di ATRP, KATRP. Sostanzialmente con questo strumento è stata seguita la reazione tra CuI e RX, come avveniva per la misura di kact, ma in questo caso non si è introdotto nel sistema un catturatore radicalico, che serviva per isolare cineticamente lo step di attivazione. Quindi le reazioni di attivazione, disattivazione e terminazione radicalica sono state contemporaneamente monitorate e il valore di KATRP è stato ottenuto dall’elaborazione del responso elettrochimico tramite un’equazione, originariamente proposta da Fischer e in seguito opportunamente modificata. Il metodo è stato applicato a diversi catalizzatori, iniziatori, combinazioni di solvente e monomero e temperature, osservando dei trends nelle costanti in accordo con i principi di ATRP. KATRP e kact devono essere determinate in assenza di ioni alogenuro, i quali influenzano fortemente la speciazione dei complessi di CuI. Infatti, la quantità della specie attiva [CuIL]+ viene diminuita a causa della formazione di specie di CuI variamente alogenate, di conseguenza la sua reazione con RX risulta rallentata. Dalla riduzione nella velocità con cui CuI viene consumato al variare di C_(X^- ) è stato possibile stimare la costante di associazione di X− a [CuIL] + (o alidofilicità di CuI, K_X^I). Viene quindi presentata una procedura per determinare K_X^I dai valori di K_ATRP^app, determinati via RDE in presenza di diverse concentrazioni di X−. Oltre a fornire strumenti per studi di tipo meccanicistico, l’elettrochimica viene usata anche come driving force del processo di polimerizzazione. Infatti, un potenziale o una corrente possono essere applicati al sistema per rigenerare la specie di CuI, da [X–CuIIL]+ che si accumula in seguito al verificarsi di reazioni di terminazione radicalica. La polimerizzazione radicalica per trasferimento di atomo mediata elettrochimicamente (eATRP) sfrutta gli elettroni come agenti riducenti, quindi non porta alla formazione di sottoprodotti e consente di usare come reagente un sale di CuII, stabile all’aria, che viene poi ridotto in situ. Il tradizionale setup per eATRP richiede però un potenziostato e costosi elettrodi di Platino. Durante il mio periodo di dottorato ho cercato di semplificare il setup di eATRP, così da rendere questa tecnica più conveniente e realizzabile su larga scala. Alcuni materiali non costosi e facilmente funzionalizzabili sono stati testati come catodi in solventi organici e in sistemi acquosi. Polimerizzazioni ben controllate sono state ottenute con gli elettrodi lavoranti analizzati, anche operando in modalità galvanostatica (i.e. applicando step a corrente costante), la quale consente di utilizzare due elettrodi anziché tre, e di sostituire il potenziostato con un semplice generatore di corrente. Inoltre, questi catodi hanno dato ottimi risultati anche in combinazione con un anodo sacrificale di Alluminio, quindi realizzando un setup completamente Pt-free. Infine, è stato dimostrato che questi materiali non rilasciano ioni metallici in soluzione e che la loro morfologia non viene modificata nel corso delle polimerizzazioni, pertanto possono essere riutilizzati in reazioni successive. Caratteristica distintiva dell’eATRP e della ATRP in generale è l’eccezionale versatilità di queste tecniche, che consentono di polimerizzare diverse tipologie di monomeri. Per molti anni però, fu ritenuto impossibile controllare la polimerizzazione di monomeri acidi via ATRP. Nel 2016, Fantin et al. hanno dimostrato che le catene propaganti di poli(acido metacrilico) tendono a ciclizzare, con conseguente perdita della funzionalità C–X, quindi terminazione. Una volta definite le condizioni adatte per evitare questa pericolosa reazione secondaria, è stato possibile controllare efficacemente la polimerizzazione dell’acido metacrilico tramite eATRP. Questa importante vittoria mi ha permesso di lavorare con successo alla polimerizzazione dell’acido acrilico (AA), monomero biocompatibile, usato in moltissimi settori. Innanzitutto è stato dimostrato che la propagazione di AA è affetta dalla stessa reazione parassita di ciclizzazione, quindi alcune delle condizioni che hanno permesso l’efficace eATRP dell’acido metacrilico, sono state adattate al sistema analizzato. i) Il sale bromurato è stato sostituito da un sale clorurato, ii) la velocità di polimerizzazione è stata massimizzata usando un elettrodo lavorante con elevata area superficiale, applicando un potenziale molto più negativo di quello standard di riduzione del catalizzatore e ottimizzando la composizione del sistema. Un modo efficace per aumentare l’applicabilità della ATRP consiste nella sintesi di nuovi leganti che conferiscano particolari proprietà al centro metallico. Nella tesi sono riportati 4 nuovi leganti, in cui lo scheletro del legante tris-2(metilpiridil)ammina (TPMA), comunemente usato in ATRP, è stato modificato con sostituenti fenilici variamente funzionalizzati in posizione meta. La caratterizzazione elettrochimica dei complessi di Cu con questi leganti ha portato a predire una minore attività rispetto al tradizionale Cu/TPMA. Questa è stata confermata dalla determinazione di kact tramite RDE. Ciononostante, questi complessi sono risultati efficaci catalizzatori in eATRP di metil metacrilato in DMF, e di oligo(etilene glicole)metil etere metacrilato e di acido metacrilico in acqua. Nonostante la non elevata attività, i complessi analizzati hanno mostrato buona stabilità in acqua, anche a pH acido, e si propongono come catalizzatori adeguati per sistemi altamente reattivi. La versatilità di queste polimerizzazioni si riflette nella possibilità di applicazione in un’ampia varietà di ambienti. Grande interesse, ad esempio, è rivolto all’utilizzo di Liquidi Ionici (ILs) come solventi di polimerizzazione “green”. Pertanto, le proprietà redox di alcuni catalizzatori e iniziatori, frequentemente usati in ATRP, sono state studiate tramite CV in 1-butil-3-metilimidazolio trifluorometansolfonato. Nello stesso sono stati effettuati studi cinetici via RDE. Queste analisi hanno permesso di affermare che il comportamento dei composti di Cu e degli alogenuri alchilici in IL è del tutto simile a quello osservato nei solventi organici tradizionali. Perciò, i liquidi ionici si confermano come solventi adatti a processi di polimerizzazione controllata. Appare infine auspicabile realizzare eATRP in ILs, perché la buona conducibilità elettrica di questi solventi consente di evitare l’aggiunta di un elettrolita di supporto. Un ulteriore ambiente sostenibile di polimerizzazione è rappresentato dai sistemi dispersi. Sebbene moltissime polimerizzazioni su scala industriale si basino su sistemi in (mini)emulsione, la maggior parte della letteratura che tratta di ATRP riporta processi in soluzione omogenea. La realizzazione di ATRP in miniemulsione ha richiesto la sintesi di opportuni leganti super-idrofobici, che consentissero di confinare il catalizzatore nella fase dispersa idrofobica, dove potesse esercitare il suo effetto. Durante il mio dottorato ho trascorso sei mesi come visiting student presso la Carnegie Mellon University, nei laboratorio del Prof. Matyjaszewski, che scoprì l’ATRP nel 1995. In quel periodo ho potuto lavorare estesamente su ATRP in miniemulsione ed emulsione. Un nuovo sistema catalitico è stato messo a punto e applicato con efficacia in eATRP e ARGET-ATRP (attivatori rigenerati per trasferimento elettronico, in cui un agente riducente è usato per rigenerare continuamente CuI). Catalizzatori idrofilici tradizionali sono stati usati in combinazione con surfattanti anionici poco costosi, formando coppie ioniche capaci di entrare negli agglomerati monomerici e catalizzare la polimerizzazione. L’interazione tra le specie reagenti è stata provata attraverso caratterizzazioni elettrochimiche e spettrochimiche, che hanno permesso di definire il diverso contributo di catalisi interfacciale e via coppie ioniche. Grazie a questo approccio sono stati prodotti copolimeri a blocchi, a stella e a spazzola. Inoltre il Cu residuo nei polimeri precipitati è risultato estremamente poco, in alcuni casi inferiore ad 1 ppm, quindi i polimeri non necessitano di ulteriore purificazione. Il sistema catalitico è stato poi applicato in ARGET-ATRP in emulsione, sfruttando la presenza di un catalizzatore idrofilico, essenziale in emulsione dove la polimerizzazione deve verificarsi in fase acquosa. ARGET-ATRP ben controllate in emulsione ab initio sono state ottenute, anche con basse quantità di surfattante, ottimizzando la procedura di pre-emulsificazione, la velocità di mescolamento e selezionando opportuni iniziatori idrofilici.

L’objet de cette thèse est d’étudier un procédé de fraisage par microélectroérosion (μEE), qui est un procédé sans contact permettant d’usiner tous les matériaux durs conducteurs d’électricité à l’aide d’un micro-outil cylindrique ultrafin. Le principe consiste à créer des micro-décharges électriques entre le micro-outil et une pièce conductrice immergés dans un diélectrique liquide. En faisant parcourir à l’outil un parcours 3D, il est possible de creuser une forme complexe dans la pièce avec des détails à fort rapport d’aspect. Dans ce travail, nous avons tout d’abord amélioré un procédé d’élaboration de microoutils cylindriques ultrafins par gravure électrochimique de barreaux de tungstène. Des outils de diamètre 32,6 ± 0,3 μm sur une longueur de 3 mm ont été obtenus de manière automatique et reproductible. L’écart type a été divisé par 2 par rapport à l’état de l’art antérieur. Des outils de diamètre inférieur ont été obtenus avec une intervention de l’opérateur, et ce jusqu’à 3 μm de diamètre. Puis ces micro-outils ont été mis en oeuvre pour usiner des pièces avec le procédé de fraisage par microélectroérosion. Pour ce faire, une machine de 2ème génération a été entièrement développée sur la base de travaux antérieurs. Il a été possible d’usiner de l’acier inoxydable dans de l’eau déionisée avec des micro-outils de 3 μm de diamètre sans détérioration de l’outil. Par ailleurs, Le procédé de μEE a été caractérisé en termes de résolution d’usinage, taux d’enlèvement de matière et usure de l’outil. Un générateur de décharges original a permis d’usiner avec des micro-décharges de 1 à 10 nJ / étincelle avec une diminution très sensible de l’usure de l’outil par rapport à l’état de l’art. Un procédé original de caractérisation en ligne des décharges et de cartographie dans l’espace a aussi été développé<br>This work aims at studying Micro Electrical Discharge Milling (μEDM milling), which is a non-contact process allowing machining all hard and electrically conductive materials with a cylindrical ultrathin tool. The principle is based on the creation of electrical micro discharges between the tool and an electrically conductive part immersed in a liquid dielectric. By means of a 3D path, the tool machines a complex shape in the part with high aspect ratio details. In this work, we have firstly improved a process for making cylindrical ultrathin micro-tools by electrochemical etching of tungsten rods. Tools with a diameter of 32.6 ± 0.3 μm and a length of 3 mm have been obtained with an automated and reproducible process. Standard deviation has been divided by 2 by comparison with the previous state of the art. Tools with diameter as low as 3 μm have been fabricated with the help of the machine operator Then these micro-tools have been used for machining parts with the μEDM milling process. To do so, a second generation machine has been entirely developed on the basis of previous work. It has been possible to machine stainless steel in deionized water with 3 μm micro-tools without damaging the tools. In other respects, the μEDM milling process has been characterized in terms of machining resolution, material removal rate and tool wear. An innovative generator of discharges allow machining with 1 to 10 nJ / spark with a reduced tool wear by comparison to the state of the art. An innovative process for the on line characterization of discharges with spatial distribution capability has been developed

The master’s thesis deals with the topic of electrical discharge machining. The first part of the thesis contains a study of the die-sinking EDM. The die-sinking EDM of the silicon carbide ceramic is realized in the experimental part of the thesis. The result of this work was to explore the influence of the EDM sinking parameters, specifically pulse current, open-voltage and pulse on-time, on the machined surface. Furthermore, the analysis of the tool electrode was made. This analysis was focused on the wear in the corners, which has key influence on accuracy of the machining. The machining time was also examined.

L’électroérosion (EE) est une technique d’usinage sans contact de matériaux conducteursd’électricité ; elle particulièrement bien adaptée à l’usinage de matériaux durs. Le principe consiste àcréer des décharges électriques érodantes entre un outil et une pièce à usiner, toutes deuximmergées dans un diélectrique. Dans cette thèse, nous avons étudié la miniaturisation de ceprocédé, la microélectroérosion (μEE), qui se présente comme un procédé complémentaire destechniques de micro-usinage mécanique, laser, ou encore des techniques issues de lamicrotechnologie du silicium (RIE, DRIE, LIGA). Toutefois, la résolution de la μEE est limitée.Dans ce travail, nous avons tout d’abord développé un procédé original d’élaboration de microoutilscylindriques en tungstène par gravure électrochimique. Celui-ci permet d’obtenir de manièrereproductible des micro-outils de diamètre 15 μm et de rapport hauteur sur diamètre supérieur à 50.Des micro-outils plus fins ont aussi été obtenus (jusqu’à 700 nm) mais avec des problèmes dereproductibilité. Par ailleurs, un prototype de machine de fraisage par μEE a été développé avec uneélectronique entièrement caractérisée. Des micro-canaux de 40 μm de largeur ont été obtenus dansl’acier d’inoxydable et 25 μm dans le titane ; une rugosité Ra de 86 nm a été atteinte dans des cavitésde 600 x 600 x 30 μm. Les limitations du dispositif expérimental ont aussi été mises en évidence.Dans la dernière partie de ce travail, nous avons procédé à l’étude des microdécharges et du microplasmas’établissant entre micro-outil et pièce à l’aide de caractérisations électriques. La résistanceet l’inductance des décharges ont été déterminées expérimentalement puis intégrées dans unmodèle permettant de prévoir la durée des impulsions de courant et leur intensité. Des pistes pourl’amélioration de la résolution d’usinage sont proposées en conclusion de ce travail<br>Electro Discharge Machining (EDM) is a non-contact technique allowing machining of electricallyconductive materials; it is well adapted for the machining of hard materials. The principle is based onthe creation of eroding electrical discharges between a tool and a piece, both immersed in adielectric. In this thesis, we have the studied miniaturization of the process, called micro electrodischarge machining (μ-EDM), which is considered as a complementary technique of mechanical orlaser micro-machining techniques and silicon micro technology processes (RIE, DRIE, LIGA)..However, the resolution of μEDM is limited.In this work, we have firstly developed an original method for making tungsten micro-tools withcylindrical profile by electrochemical etching. This method allows the reproducible fabrication ofmicro-tool with 15-μm diameter. Thinner micro-tools were also obtained (down to 700 nm) withreproducibility problems. Furthermore, a prototype machine for milling μ-EDM was developed with afully characterized electronics. Micro channels were obtained respectively in stainless steel with awidth of 40μm and in titanium with a width of 25μm; a surface roughness Ra of 86 nm was achievedin 600 x 600 x 30 μm cavities. Besides, the limitations of the apparatus were highlighted. In the lastpart of this work, we have studied the micro-discharge and the micro-plasma between the micro-tooland the part with electrical characterization. The resistivity and the inductance of the sparks weremeasured and integrated in a numerical model in order to explain the duration of the microdischarges and their intensity. Solutions for improving the machining resolution are also discussed atthe end of this work

Neuromodulation therapies are now common treatments for a variety of medically refractory disorders, including movement disorders and epilepsy. While surgical techniques for each disorder vary, electricity is used by both for relieving symptoms. During stereotactic placement of the stimulating electrode, either deep brain stimulation electrodes or cortical strip electrodes, intraoperative neurophysiology is used to localize the target structure. This physiology includes single-unit recordings, neurostimulation evoked response evaluation, and intracranial electroencephalography (EEG) to ensure the electrode leads are in the optimal location. Because the functional target for the responsive neurostimulator is more easily visualized on preoperative magnetic resonance imaging, intraoperative physiology is used more as a confirmatory tool, in contrast to the more functional localization-based use during electrode placement for movement disorders. This chapter discusses surgical placement of the electrodes for each procedure and the physiological guidance methodology used to place the leads in the optimal location.

Systems neuroscience is being revolutionized by the ability to record the activity of large numbers of neurons simultaneously. Chronic recording with multi- electrode arrays in animal models is a critical tool for studies of learning and memory, sensory processing, motor control, emotion, and decision-making. The experimental process for gathering large amounts of neural ensemble data can be very time consuming, however, the resulting data can be incredibly rich. We present a detailed overview of the process of acquiring multichannel neural data, with a particular focus on chronic tetrode recording in rodents.

Device-based neuromodulation is an emerging tool with great potential for significant scientific and clinical implications for a number of mental disorders. Neuromodulation techniques deliver electro-magnetic pulses into the brain via invasive or noninvasive electrodes, with various timing and stimulation parameters. The stimulation is thought to work as a “brain pacemaker” that either activates or inactivates targeted brain regions to restore normal homeostasis. There have been significant recent efforts to explore the clinical utility of device-based approaches for the treatment of mood, anxiety disorders, and to a limited extent posttraumatic stress disorder (PTSD). This chapter outlines the scientific underpinnings and rationale for various device-based treatments of PTSD, highlights positive results of studies in other mental disorders, and summarizes the limited clinical data related specifically to the treatment of PTSD and other trauma- and stressor-related disorders to date.

AbstractTranscranial current stimulation (tCS or tES) protocols yield results that are highly variable across individuals. Part of this variability results from differences in the electric field (E-field) induced in subjects’ brains during stimulation. The E-field determines how neurons respond to stimulation, and it can be used as a proxy for predicting the concurrent effects of stimulation, like changes in cortical excitability, and, ultimately, its plastic effects. While the use of multichannel systems with small electrodes has provided a more precise tool for delivering tCS, individually variable anatomical parameters like the shape and thickness of tissues affect the E-field distribution for a specific electrode montage. Therefore, using the same montage parameters across subjects does not lead to the homogeneity of E-field amplitude over the desired targets. Here we describe a pipeline that leverages individualized head models combined with montage optimization algorithms to reduce the variability of the E-field distributions over subjects in tCS. We will describe the different steps of the pipeline – namely, MRI segmentation and head model creation, target specification, and montage optimization – and discuss their main advantages and limitations.

Abstract To control the casing's severe CO2 inner corrosion and minimize damage to oil wells drilled into the Yan'an formation of Jurassic reservoirs; internal plastic coating was applied to the portion of the casing below the dynamic liquid level (nearly 700 m) for each of the more than 4000 wells drilled over the last 10 years. Considering the cost factor, it was not economic for the whole wellbore to have internal coating, so only the section with serious internal corrosion was internally coated with a modified epoxy-phenolic. This kind of modified epoxy-phenolic coating has excellent mechanical and anti-corrosion performance. But it’s difficult to analyze the long term aging or local mechanical damage of downhole inner coating. New approaches by electrode logging tools have been studied for monitoring the inner coating.

Abstract Carbon steels are susceptible to stress corrosion cracking (SCC) in ethanol. The propensity for SCC strongly depends on the potential of the carbon steel and the oxygen concentration of the ethanol. Thus, a rugged reference electrode to reliably monitor the potential of steel in ethanol and a tool that can measure oxygen concentration in ethanol are desired to provide sufficient knowledge in determining the SCC susceptibility. The gel reference electrode used in this work showed sound performance for use in ethanol to monitor the corrosion potential of carbon steel. Compared to conventional reference electrodes, it has a small leaking rate and thus can reduce the contamination of the tested environment significantly. Furthermore, unlike an electrode with a liquid filling solution, constant maintenance is not needed because a polymer gel was used, which makes the electrode an ideal candidate for use in pipeline and storage tanks for long term potential monitoring. The oxygen concentration was measured with an optical oxygen probe. Oxygen is approximately ten times more soluble in ethanol than in water. The evaluated probe responds to the environment changes quickly and precisely and is a good tool to monitor oxygen concentration in ethanol as a way to determine the SCC propensity of the steel.

Abstract Corrosion can be accelerated by fluid flow. An overview is presented of the relationships among mass transfer coefficient, fluid velocity, shear stress, and fluid properties for several geometries. Equations are presented that allow rotating (inner) cylinder electrode velocities to be chosen so that the mass transfer coefficients are equal to those in pipes, concentric annuli, and wall jets. The suggestion is made that equality of shear stress in two configurations may sometimes be used as one criterion to insure that the fluid affected corrosion mechanism in one configuration is duplicated in the other. The second criterion is that the flow regimes must be the same (e.g. turbulent). Results are presented to show how the rotating cylinder electrode might be used as a practical laboratory tool to simulate and predict certain types of velocity sensitive corrosion. This tool can be used in either an electrochemical or in a gravimetric mode to make this prediction.

Abstract The development of microelectrode technique lasted over twenty years. As an electrochemical method, it is mainly used to detect local electric potential, e.g., membrane potential in biology and localized corrosion potential in corrosion science. Besides as a fixed electrode, it is also often used to compose a microelectrode scanning apparatus, which may be applied to study potential distribution on surface of a localized corroding sample and by which, more detailed information of this sample may be obtained and analyzed. However, because the scanning is mechanically driving, the time of several minutes is needed for the scanning process, therefore it would be impossible to measure the transient surface potential distribution. So, once a fast electrochemical corrosion process occurs at some position on the surface, and the conventional scanning microelectrode is not passing there, this process and its variation would be omitted, and it is very likely that this process and the variation of the transient potential distribution can provide more information and help us to understand and analyze the electrochemical characteristics of the corroding sample. To solve this problem, we have designed a new electrochemical method, i.e., collected-microelectrode method (1), and set up this system. Preliminary experiments show that this system is more sensitive, convenient and less restricted.

Abstract Microbiologically Induced Corrosion (MIC) takes place in harbors, nuclear plants, oil industry structures and most production plants. MIC is often observed as a localized corrosion (pits)[1,2], which can evolve into uniform corrosion. Previous work enabled a special sensor to be developed dedicated to the detection of localized biocorrosion of carbon steel structures. This sensor is based on the corrosion initiation of a small electrode which is then connected to a large electrode by a zero resistance ammeter that enables the measurement of the naturally flowing corrosion current. The anode area is small enough to make corrosion occur on its whole surface and to consider that the coupled electrodes simulate a localized biocorrosion process. Either an electrochemical or a mechanical procedure can be used effectively for corrosion initiation conditioning step. This sensor is used for this work as a tool to investigate the biocorrosion process by Electrochemical Impedance Spectroscopy (EIS). The spectra recorded enable changes in kinetics and in surface properties to be analyzed. Due to the sensor principle, the anode and cathode surfaces are clearly defined, and the simultaneous investigation of both electrodes is possible. The investigation carried out on the electrodes shows modifications in Polarization Resistance (Rp) as well as Electrolyte Resistance (Re) and Capacity (C) indicating changes in surface properties. As the experiments are performed in the presence of a SRB biofilm, which is able to induce extensive localized corrosion, conditioning procedures are assumed to be the main actors in the evolution of the MIC process.

Abstract Existing coupled multielectrode array sensors are promising devices for application as an online tool for corrosion monitoring. However, most of these devices have an upper operating temperature limit of approximately 70 °C. At temperatures above 70 °C, crevice formation between the electrode and the mounting material (epoxy) may result in erroneous corrosion rate measurements. In this paper, a new electrochemical corrosion monitoring system that has high temperature (&amp;gt;100 °C) capability is presented. A diamond-like carbon thin film was deposited on the sensing electrodes. The coated surfaces exhibited high electrical impedance after testing in caustic (pH = 10) solution at 250 °C. The effectiveness of the diamond-like carbon film in protecting the electrodes was demonstrated in a corrosive solution containing NaCl-NaNO3-KNO3 salt mixture at 150 °C. The new corrosion monitoring system has potential application for monitoring corrosion rate for container materials in potential nuclear waste repositories and in the high temperature systems of nuclear power plants.

Abstract Many magnesium alloys exhibit microgalvanic corrosion due to anodic and cathodic reactions that occur at discrete phases. We used the scanning vibrating electrode technique (SVET) to map the local corrosion current distribution profile of specially designed magnesium and aluminum galvanic couples. We studied the effect of anode (Mg) to cathode (Al) area ratio (A/C = 1:9, 3:7 and 1:1) and the effect of electrolyte concentration (sodium chloride solutions, 10, 30, and 280 mM). The galvanic current density is mapped for different immersion time intervals (t= 0 and 1 hour). The SVET response clearly showed that anodic and cathodic current densities on the magnesium and aluminum (Mg-Al) galvanic couple, respectively. The current density decreased with increasing anode to cathode surface area ratio, and at a given ratio, increased with increasing concentration of the sodium chloride solution. Our results showed that SVET can provide finite current/potential details of the microgalvanic activities within magnesium alloys, which are not possible with conventional electrochemical measurements, and it is an excellent measurement tool for understanding microgalvanic corrosion of magnesium alloys.

Abstract The need to know the contaminant level of steam has been met by the on-line use of a continuous analyzer based on a sodium ion-specific electrode. But while such an instrument provides the accuracy and sensitivity required, it does not assure reliable results unless the sample being delivered to the electrode is truly representative of the stream being evaluated. Correct sample collection and delivery procedures must be strictly followed. Boiler water carryover consists of liquid and vaporous carryover. Sodium will accurately assess the liquid carryover of industrial boilers, but the problem becomes more difficult at higher pressures because of the increased tendency toward vaporous carryover as pressures and temperatures increase. The sodium analyzer can be used as a tool for optimizing boiler water control limits to minimize blowdown rates while still assuring adequate steam purity. It can also be used as a troubleshooting tool to determine the cause of many deposit and corrosion related problems around a steam system. In addition, the analyzer has been used on demineralizer effluents to adjust acid regenerant levels to reduce acid and waste disposal costs and to allow for optimization of boiler water treatment when on a captive alkalinity program. A unique use for the analyzer is as a monitor for the high purity water injection stream into gas turbines for NOX control.

Abstract The effect of turbulent flow conditions on the kinetics and mechanism of two relevant corrosion processes is studied and analyzed: inhibitors evaluation and electrochemical behavior of cathodic protection galvanic anodes. In all these cases, the rotating cylinder electrode, RCE, becomes a useful and valuable tool to study the mass transfer process involved which typically is the rate determining step of corrosion mechanism. It was found that under turbulent flow conditions, the corrosion rate linearly increased as the RCE’s rotation rate also increased and the overall electrochemical corrosion process was influenced by the oxygen mass transfer process on the cathodic kinetics.

Abstract Traditional forecasts of steel corrosion in concrete can be markedly inadequate if based on chloride threshold (CT) values that do not evolve with structure age. Previous work that considered the increase in CT due to macrocell-induced steel potential drop around newly corroded steel zones showed that the traditional forecast can be much too conservative at long service ages, while insufficiently so at early ages. In that work, CT was simplified as a single function of steel potential. Here we take initial steps to consider not only that local (intrinsic) effect, but also the (extrinsic) effect from the macrocell electric fields on the distribution of chloride and hydroxide ions. Those factors are implemented in a tentative finite element multiphysics time evolution model, coupled with electrode reactions at the steel surface. Model viability is assessed. The ultimate goal is to produce damage functions to serve as a powerful tool for deciding on alternative corrosion control approaches.

This report introduces the Variable Frequency Impedance Tomography (VFIT) method for assessing the effectiveness of non-interruptible power supplies (sacrificial anodes) for protecting coated buried pipe. This method imposes a low-amplitude alternating voltage between the pipe and a reference electrode placed on the surface. A potentiostat/galvanostat controls the electric potential by modulating the current between the pipe and a surface counter electrode. The principle interpretive tool used in this study was an Artificial Neural Network (ANN) that had been \trained\" on simulated pipe with a defective coating and on field data from a test pipe.

The performance and accuracy of quantum electronics is substantially degraded when the temperature of the electrons in the devices is too high. The electron temperature can be reduced with appropriate thermal anchoring and by filtering both the low frequency and radio frequency noise. Ultimately, for high performance filters the electron temperature can approach the phonon temperature (as measured by resistive thermometers) in a dilution refrigerator. In this application note, the method for measuring the electron temperature in a typical quantum electronics device using Coulomb blockade thermometry is described. This technique is applied to find the readily achievable electron temperature in the device when using the QFilter provided by QDevil. With our thermometry measurements, using a single GaAs/AlGaAs quantum dot in an optimized experimental setup, we determined an electron temperature of 28 ± 2 milli-Kelvin for a dilution refrigerator base temperature of 18 milli-Kelvin.

Analytical chemistry is the one of the most importance not only to all branches of chemistry but also to all the biological sciences, to engineering, and, more recently, medicine, public health, food, environment and the supply of energy in all forms. Therefore, the developments of novel detection methods play an important role to obtain both qualitative analysis and quantification of the chemical or biomolecule components of natural and artificial materials. This work has been separated into 3 groups for finishing the novelty in detection methods. First, novel nanomaterials-based or nanocomposite chemical sensors based on nanomaterial/conducting polymer will be prepared and used to modify the electrode surface for sensitive electrochemical and/or optical detection of chemicals and biomolecules. The bioreceptor functionalization will be applied if it is necessary. Under the optimal conditions, the proposed system will be used for sensitive detection of target analytes (e.g. heavy metals, pesticides, food contaminants and biomolecules). This approach is an alternative tool for environmental monitoring, food inspection as well as clinical diagnosis. Second, the paper-based device is proposed. They have the potential to be good alternatives for point-of-care testing because they are portable, easy to use, require only a small volume of sample and provide rapid analysis. To create the detection method for lab-on-paper, colorimetric and electrochemical detection are proposed. These provide the benefits of simplicity, speed, low cost, and portability for applying to various applications. Last, a simple microfluidic or sequential injection system for chemical or biomedical analysis will be developed. Exploiting a microfluidic or sequential injection system, short analysis times can be achieved with high analytical performances, in addition, only small amount of samples and reagents are required, which is beneficial for samples which are expensive or limited, especially biological samples. Moreover, microfluidic or sequential injection analysis holds great promise for high-throughput analysis and screening, which offers an alternative platform for analysis and would be an ideal tool for a portable analysis system for clinical diagnosis.

Pipe-to-soil potential measurements are the primary means for monitoring the effectiveness of cathodic protection (CP) systems. All criteria for cathodic protection employ, in one form or another, a potential measurement of the pipe with respect to a reference electrode. Although the pipeline industry obviously depends on pipe-to-soil potential measurements for monitoring CP systems, very little is known concerning what portion of the pipe is being sampled by the potential measurement. Prior to performing this project, many questions remained unanswered, such as: (1) what is the length of pipe being sampled by aboveground measurements, (2) is the potential sampled an average value around the circumference of the pipe or do above-ground measurements sample only the potential at the top of the pipe, and (3) how far away can a holiday or potential anomaly be detected. The overall objective of this research program was to improve the ability to perform and interpret close interval on-potential and off-potential surveys. The following general conclusion can be made based on the results of this study. Ground level potential measurements provide average potential values, which are weighed based on pipe diameter, pipe depth, coating versus bare pipe, and other factors. Thus, close interval surveys should be considered as another tool to provide information on the condition of the pipe but should not be interpreted as providing definitive information on that condition. Benefit: This research was a three-year program conducted for the Corrosion Supervisory Committee of PRCI with the main focus directed at establishing the area of pipe sampled during a pipe-to-soil potential measurement. The program was divided into two parts: bare pipelines and coated pipelines. The work examining bare pipelines was performed during 1988 and 1989, and the work examining coated pipelines was performed during 1990. The overall objective of this program was to improve the ability to perform and interpret close-interval potential surveys.

This article discusses the current state of neurointerface technologies, not limited to deep electrode approaches. There are new heuristic ideas for creating a fast and broadband channel from the brain to artificial intelligence. One of the ideas is not to decipher the natural codes of nerve cells, but to create conditions for the development of a new language for communication between the human brain and artificial intelligence tools. Theoretically, this is possible if the brain "feels" that by changing the activity of nerve cells that communicate with the computer, it is possible to "achieve" the necessary actions for the body in the external environment, for example, to take a cup of coffee or turn on your favorite music. At the same time, an artificial neural network that analyzes the flow of nerve impulses must also be directed at the brain, trying to guess the body's needs at the moment with a minimum number of movements. The most important obstacle to further progress is the problem of biocompatibility, which has not yet been resolved. This is even more important than the number of electrodes and the power of the processors on the chip. When you insert a foreign object into your brain, it tries to isolate itself from it. This is a multidisciplinary topic not only for doctors and psychophysiologists, but also for engineers, programmers, mathematicians. Of course, the problem is complex and it will be possible to overcome it only with joint efforts.