Search

The goal of this work is to examine the effect of hot deformation on shrinkage porosity and nonmetallic inclusions in an AISI 1070 grade steel industrially produced wheel casting. Steel cleanliness is an important consideration as it influences the mechanical properties of the final product. A high density of porosity and inclusions have been shown to be detrimental for mechanical properties, especially during hot rolling. Using a laboratory-scale rolling mill, cast preforms were subjected to a 66% cumulative reduction to determine the effect of thermomechanical processing on void closure and inclusions that may produce anisotropy in mechanical properties. Quantitative automated feature analysis, AFA, of inclusion type, size, morphology, and distribution was conducted utilizing an Aspex PICA 1020 scanning electron microscope to determine differences in inclusions and shrinkage porosity in the as-cast and as-rolled conditions. The results were compared with previously reported impact toughness values which indicated a trend with MnS projected length and average impact toughness in the T-L orientation. Reduction in shrinkage porosity was also verified utilizing 3D micro-X-ray CT scans. The AFA results showed a decrease in shrinkage porosity from 177 ppm in the as-cast condition to less than 35 ppm after rolling. Pores were in general much smaller and widely distributed after hot rolling and this would suggest improved impact properties. Analysis of nonmetallic inclusions revealed three primary categories of inclusions that included MnS, Al2O3, and complex inclusions that mainly consisted of MnS with an Al2O3 core, with small quantities of mixed silicates of Mn and Al and calcium aluminates (CaAl2O4).

John Albery was one of the most creative, innovative and distinguished physical chemists of his time. He was particularly noted for his pioneering work in electrochemistry and electroanalytical chemistry, proton transfer kinetics and isotope effects, and enzyme kinetics. His DPhil studies on rotating disc electrodes led to seminal papers in the 1960s on ring-disc electrodes, which laid the basis for the extensive development of a powerful tool for electrochemical diagnostics. Those doctoral studies also involved work on the mechanisms of proton transfer reactions, a subject that remained very dear to his heart, and later resulted in the application of Marcus theory to provide understanding of physical organic reactions. In a separate strand on kinetic processes, he developed the theory of enzyme catalysis, which gave important insights into reaction kinetics of biological catalysts. He was a marvellous teacher and an inspiration to generations of his students, both undergraduate and post-graduate. His legacy reached far and wide, with a scientific family that included more than a dozen professorial ‘offspring’. His talents were not only restricted to science but extended to the theatre and entertainment, with writing for the satirical programme That was the week that was , the production of two musicals and of numerous departmental and college cabarets and irreverent annual revues. John Albery had an irrepressible joie de vivre and was the instigator of and participant in many occasions that were full of fun and laughter and live on in the memory. But it was not all fun and games; he had a keen sense of social justice. He led the assault to admit women to the previously men-only colleges of Oxford, and in the 1970s he mounted a vigorous and successful campaign to secure permission for the great Jewish electrochemist Benjamin Levich to leave the Soviet Union.

Silica thin films with vertical nanopores are useful to control access to electrode surfaces and may act as templates for growth of nanomaterials. The most effective method to produce these films, electrochemically assisted surfactant assembly, also produces aggregates of silica particles. This paper shows that growth with an AC signal superimposed onto the potential avoids the aggregates and only very small numbers of single particles are found. This finding is linked to better control of the diffusion field of hydroxide ions that are responsible for particle growth. The resultant films are smooth, with very well-ordered hexagonal pore structures.\ud \ud

Redox cycling (RC) is a powerful tool capable of amplifying faradaic currents in electroanalytical measurements, thus allowing an enhancement of sensitivity through fast multiple sequential oxidation and reduction reactions of a redox-active analyte. Present state-of-the-art RC devices are mostly based on planar electrode geometries either in 2D or 3D configurations, requiring cleanroom facilities and expensive microfabrication techniques. Here, the electrochemical elaboration and characterization of a 3D coaxial macroporous twin-electrode is reported, obtained by following a low-cost bottom-up approach. A nanoengineered highly organized porous material is the basis for the design of two threaded cylindrical porous gold microelectrodes with a gap in the micrometer range that can be fine-tuned. The potentials of the outer and inner electrodes are biased at values above and below the redox potential of the analyte so that a given molecule can participate several times in the electron exchange reaction by shuttling between both electrodes. The resulting signal amplification, combined with a straightforward synthesis strategy of the electrode architecture, allows envisioning numerous (bio)electroanalytical applications.

Memristors are emerging as promising candidates for practical application in reservoir computing systems that are capable of temporal information processing. Here, we experimentally implement a physical reservoir computing system using resistive memristors based on three-dimensional (3D)-structured mesoporous silica (mSiO2) thin films fabricated by a low cost, fast and vacuum-free sol–gel technique. The in situ learning capability and a classification accuracy of 100% on a standard machine learning dataset are experimentally demonstrated. The volatile (temporal) resistive switching in diffusive memristors arises from the formation and subsequent spontaneous rupture of conductive filaments via diffusion of Ag species within the 3D-structured nanopores of the mSiO2 thin film. Besides volatile switching, the devices also exhibit a bipolar non-volatile resistive switching behavior when the devices are operated at a higher compliance current level. The implementation of mSiO2 thin films opens the route to fabricate a simple and low cost dynamic memristor with a temporal information process functionality, which is essential for neuromorphic computing applications.

Metallic nanostructures have widespread applications in fields including materials science, electronics and catalysis. Mesoporous silica films synthesised by evaporation induced self-assembly and electrochemically assisted self-assembly with pores below 10 nm were used as hard templates for the electrodeposition of Au nanostructures. Electrodeposition conditions were optimised based on pore orientation and size. The growth of nanostructures was initiated at the electrode surface as confirmed by microscopy. The hard templates and Au electrodeposits were characterised electrochemically as well as with X-ray diffraction, small angle scattering and transmission electron microscopy. Finally, mesoporous silica hard templates were removed by hydrofluoric acid etching and stable Au nanoparticles on different electrode surfaces were achieved.

We report on the development of hybrid organic−inorganic material-based flexible memristor devices made by a fast and simple electrochemical fabrication method. The devices consist of a bilayer of poly(methyl methacrylate) (PMMA) and Te-rich GeSbTe chalcogenide nanoscale thin films sandwiched between Ag top and TiN bottom electrodes on both Si and flexible polyimide substrates. These hybrid memristors require no electroforming process and exhibit reliable and reproducible bipolar resistive switching at low switching voltages under bothflat and bending conditions. Multistate switching behavior can also be achieved by controlling the compliance current (CC). We attribute the switching between the high resistance state (HRS) and low resistance state (LRS) in the devices to the formation and rupture of conductive Ag filaments within the hybrid PMMA/GeSbTe matrix. This work provides a promising route to fabricate flexible memory devices through an electrodeposition process for application in flexible electronics.

The coronavirus disease 2019 pandemic had deleterious effects on the healthcare systems around the world. To increase intensive care units (ICUs) bed capacities, multiple adaptations had to be made to increase surge capacity. In this editorial, we demonstrate the changes made by an ICU of a midwest community hospital in the United States. These changes included moving patients that used to be managed in the ICU to progressive care units, such as patients requiring non-invasive ventilation and high flow nasal cannula, ST-elevation myocardial infarction patients, and post-neurosurgery patients. Additionally, newer tactics were applied to the processes of assessing oxygen supply and demand, patient care rounds, and post-ICU monitoring.

We present a superhydrophobic surface capable of recovering the lubricious gas layer known as the "plastron"from a fully wetted state underwater. It is shown that full plastron recovery is possible without a second layer of structural hierarchy, which is prone to irreversible wetting transitions. This allows us to use a cheap, fast, and potentially scalable method to fabricate the surface from silicone and carbon black in a molding process. We demonstrate plastron recovery from the fully wetted state and immediate plastron recovery after pressure-induced wetting transitions. The wetting state can be measured remotely and quickly by measuring the capacitance. The slip length is measured as a 135 μm, agreeing well with the theory given the geometry of the surface. The ability of the surface to conform to small radii of curvature and withstand damage from loading is also demonstrated. The work presented here could allow superhydrophobic surfaces to reduce drag on ships and in pipes where the plastron would otherwise rapidly dissolve.

Electrodeposition is a powerful tool for the bottom-up fabrication of novel electronic devices. This necessitates a complete understanding of the deposition process beyond the classical description using current transients. Recent calculations predict deviations within the spatial arrangement of electrodeposited particles, away from random nucleation. The spatial arrangement of Au particles generated through aqueous electrodeposition on a nontemplated substrate is investigated by grazing incidence small-angle X-ray scattering (GISAXS). We show that GISAXS is able to reveal spatial correlations within deposited particles that are not easily detectable by microscopy.

Weakly coordinating solvents, such as dichloromethane, have been shown to be attractive for the electrodeposition of functional p-block compound and alloy semiconductors for electronic device applications. In this work the use of solvent descriptors to define weakly coordinating solvents and to identify new candidates for electrochemical applications is discussed. A set of solvent selection criteria are identified based on Kamlet and Taft's π*, α and β parameters: suitable solvents should be polar (π* ≥ 0.55), aprotic and weakly coordinating (α and β ≤ 0.2.). Five candidate solvents were identified and compared to dichloromethane: trifluorotoluene, o-dichlorobenzene, p-fluorotoluene, chlorobenzene and 1,2-dichloroethane. The solvents were compared using a suite of measurements including electrolyte voltammetric window, conductivity, and differential capacitance, and the electrochemistry of two model redox couples (decamethylferrocene and cobaltocenium hexafluorophosphate). Ion pairing is identified as a determining feature in weakly coordinating solvents and the criteria for selecting a solvent for electrochemistry is considered. o-dichlorobenzene and 1,2-dichloroethane are shown to be the most promising of the five for application to electrodeposition because of their polarity.

The COVID-19 pandemic has led to unanticipated pressures on all aspects of human life. Multiple approaches to eliciting protective immunity must be rapidly evaluated. Numerous efforts have been made to develop an effective vaccine for this novel coronavirus, resulting in a race for vaccine development. To combat COVID-19, all nations must focus their efforts on widespread vaccination with an effective and safe vaccine. Globally, concerns about potential long-term adverse effects of vaccines have led to some apprehension about vaccine use. A vaccine's adverse effect has an integral role in the public's confidence and vaccine uptake. This article reviews the current primary literature regarding adverse effects associated with different COVID-19 vaccines in use worldwide.

Lithium battery materials can be advantageously used for the selective sequestration of lithium ions from natural resources, which contain other cations in high excess. However, for practical applications, this new approach for lithium production requires the battery host materials to be stable over many cycles while retaining the high lithium selectivity. Here, a nearly symmetrical cell design was employed to show that LiFePO4 shows good capacity retention with cycling in artificial lithium brines representative of brines from Chile, Bolivia and Argentina. A quantitative correlation was identified between brine viscosity and capacity degradation, and for the first time it was demonstrated that the dilution of viscous brines with water significantly enhanced capacity retention and rate capability. The electrochemical and X-ray diffraction characterisation of the cycled electrodes also showed that the high lithium selectivity was preserved with cycling. Raman spectra of the cycled electrodes showed no signs of degradation of the carbon coating of LiFePO4 , while scanning electron microscopy images showed signs of particle cracking, thus pointing towards interfacial reactions as the cause of capacity degradation.

The development of scalable techniques to make two-dimensional (2D) material heterostructures is a major obstacle that needs to be overcome before these materials can be implemented in device technologies. Electrodeposition is an industrially compatible deposition technique that offers unique advantages in scaling 2D heterostructures. In this work, we demonstrate the electrodeposition of atomic layers of WS2 over graphene electrodes using a single source precursor. Using conventional microfabrication techniques, graphene was patterned to create micro-electrodes where WS2 was site-selectively deposited to form 2D heterostructures. We used various characterization techniques, including atomic force microscopy, transmission electron microscopy, Raman spectroscopy and x-ray photoelectron spectroscopy to show that our electrodeposited WS2 layers are highly uniform and can be grown over graphene at a controllable deposition rate. This technique to selectively deposit transition metal dichalcogenides over microfabricated graphene electrodes paves the way towards wafer-scale production of 2D material heterostructures for nanodevice applications.

In this work, we report on the fabrication of resistive random-access memory cells based on electrodeposited GeSbTe material between TiN top and bottom electrodes in a crossbar architecture. The cells exhibit asymmetric bipolar resistive switching characteristics under the same SET and RESET compliance current (CC), showing highly uniform and reproducible switching properties. A multi-state switching behavior can be also achieved by varying the sweeping voltage and CC. Unlike phase-change switching, the switching between the high-resistance state and the low-resistance state in these cells can be attributed to the formation and rupture of conductive Te bridge(s) within the Te-rich GeSbTe matrix upon application of a high electric field. The results point toward the usage of the electrodeposition method to fabricate advanced functional device structures for application in non-volatile memory.

Lithium battery materials can be advantageously used for the selective sequestration of lithium ions from natural resources, which contain other cations in high excess. However, for practical applications, this new approach for lithium production requires the battery host materials to be stable over many cycles while retaining the high lithium selectivity. Here, a nearly symmetrical cell design was employed to show that LiFePO

We report a simple process for the electrodeposition of tungsten disulfide thin films from a CH2Cl2-based electrolyte using a tailored single source precursor, [NEt4]2[WS2Cl4]. This new precursor incorporates the 1:2 W:S ratio required for formation of WS2, and eliminates the need for an additional proton source in the electrolyte to remove excess sulfide. The electrochemical behaviour of [NEt4]2[WS2Cl4] is studied by cyclic voltammetry and electrochemical quartz crystal microbalance techniques, and the WS2 thin films are grown by potentiostatic electrodeposition.

To study the direct electron transfer (DET) of the multicofactor enzyme cellobiose dehydrogenase (CDH) in regard to its orientation on an electrode surface, a recently published, maleimide-based immobilization method was used in combination with site-directed mutagenesis to establish different orientations on an electrode surface. CDH from Myriococcum thermophilum was chosen for this study because its protein structure is resolved and the factors influencing the movement of its mobile cytochrome domain (CYT) are established. Seven CDH variants with a surface-exposed cysteine residue in different spatial positions were generated for site-specific maleimide coupling. Surface plasmon resonance and cyclic voltammetry showed that all CDH variants, but not the wild-type CDH, bound covalently to gold electrodes or glassy carbon electrodes and were catalytically active. For DET, the CYT domain needs to move from the closed-state conformation, where it obtains an electron from the catalytic flavin adenine dinucleotide (FAD) cofactor to the open state where it can donate an electron to the electrode. We therefore hypothesized that the mobility of the CYT domain and its distance to the electrode is central for DET. We found that the uniform spatial orientations of CDH influenced DET as follows: an orientation of the two-domain enzyme on the side, with CYT in proximity to the electrode, resulted in high DET currents. Orientations with a bigger distance between CYT and the electrode, or orientations where CYT could not swing back to the dehydrogenase domain to form the closed enzyme conformation, reduced DET. In the latter case, calcium ions that stabilize the closed conformation of CDH fully recovered DET. The study demonstrates that a mobile CYT domain can compensate unfavorable orientations of the catalytic domain to a great extent and allows CDH as a multicofactor enzyme to transfer electrons even in awkward orientations. The mobile CYT domain reduces the anisotropy of DET, which is also essential for CDH's physiological function as an extracellular, electron-transferring enzyme. (Less)

We report the electrodeposition of bismuth telluride thin films on to titanium nitride (TiN) electrodes from a weakly coordinating solvent, dichloromethane (CH 2 Cl 2 ), using the halometallates, [N n Bu 4 ][BiCl 4 ] and [N n Bu 4 ] 2 [TeCl 6 ] with 0.1 M [N n Bu 4 ]Cl as the supporting electrolyte. The elemental composition of the electrodeposited films was found to be independent of the deposition potential between −0.6 and −2.0 V vs. Ag/AgCl but to be dependent on ratio of the concentrations of the Bi and Te precursors in the solution, with the amount of bismuth in the films increasing when the concentration of [N n Bu 4 ][BiCl 4 ] in solution was increased. All the electrodeposited films were found to be homogenous in composition across the electrode surface and to be reproducible in composition for replicate experiments. As the deposition potential was taken less negative, the morphology of the deposits changed from uniform films to films with a compact micro/nano particle structure as seen by scanning electron microscopy (SEM). Using this system, the electrodeposition of crystalline Bi 2 Te 3 and Bi 4 Te 3 was confirmed by energy dispersive spectroscopy (EDX) and grazing incidence X-ray diffraction.

We report a simple process for the electrodeposition of tungsten disulfide thin films from a CH

Phase change memories (PCM) is an emerging type of non-volatile memory that has shown a strong presence in the data-storage market. This technology has recently attracted significant research interest in the development of non-Von Neumann computing architectures such as in-memory and neuromorphic computing. Research in these areas has been primarily motivated by the scalability potential of phase change materials and their compatibility with industrial nanofabrication processes. In this work, we are presenting our development of crossbar phase change memory arrays through the electrodeposition of GeSbTe (GST). We show that GST can be electrodeposited in microfabricated TiN crossbar arrays using a scalable process. Our phase switching test of the electrodeposited materials have shown that a SET/RESET resistance ratio of 2-3 orders of magnitude is achievable with a switching endurance of around 80 cycles. These results represent the first phase switching of electrodeposited GeSbTe in microfabricated crossbar arrays. Our work paves the way towards developing large memory arrays involving electrodeposited materials for passive selectors and phase switching devices. It also opens opportunities for developing a variety of different electronic devices using electrodeposited materials., Comment: 9 pages, 5 figures

Developing novel techniques for depositing transition metal dichalcogenides is crucial for the industrial adoption of 2D materials in optoelectronics. In this work, the lateral growth of molybdenum disulfide (MoS2) over an insulating surface is demonstrated using electrochemical deposition. By fabricating a new type of microelectrodes, MoS2 2D films grown from TiN electrodes across opposite sides are connected over an insulating substrate, hence, forming a lateral device structure through only one lithography and deposition step. Using a variety of characterization techniques, the growth rate of MoS2 is shown to be highly anisotropic with lateral to vertical growth ratios exceeding 20-fold. Electronic and photo-response measurements on the device structures demonstrate that the electrodeposited MoS2 layers behave like semiconductors, confirming their potential for photodetection applications. This lateral growth technique paves the way toward room temperature, scalable, and site-selective production of various transition metal dichalcogenides and their lateral heterostructures for 2D materials-based fabricated devices.

Waveguide enhanced Raman spectroscopy (WERS) utilizes simple, robust, high-index contrast dielectric waveguides to generate a strong evanescent field, through which laser light interacts with analytes residing on the surface of the waveguide. It offers a powerful tool for the direct identification and reproducible quantification of biochemical species and an alternative to surface enhanced Raman spectroscopy (SERS) without reliance on fragile noble metal nanostructures. The advent of low-cost laser diodes, compact spectrometers, and recent progress in material engineering, nanofabrication techniques, and software modeling tools have made realizing portable and cheap WERS Raman systems with high sensitivity a realistic possibility. This review highlights the latest progress in WERS technology and summarizes recent demonstrations and applications. Following an introduction to the fundamentals of WERS, the theoretical framework that underpins the WERS principles is presented. The main WERS design considerations are then discussed, and a review of the available approaches for the modification of waveguide surfaces for the attachment of different biorecognition elements is provided. The review concludes by discussing and contrasting the performance of recent WERS implementations, thereby providing a future roadmap of WERS technology where the key opportunities and challenges are highlighted.

Weakly coordinating solvents are of interest for the electrodeposition of p-block semiconductors for application in electronic devices. p-block complexes typically have weakly coordinated ligands that are easily displaced, making them incompatible with strongly Lewis basic solvents. In this work we use electrochemical measurements at microelectrodes to study diffusion in weakly coordinating solvents. Diffusion coefficients of the metallocenes decamethylferrocene, decamethylferrocenium hexafluorophosphate, cobaltocenium hexafluorophosphate, and the electrodeposition precursors tetrachloroantimonate(III) and tetrachlorobismuthate(III) were measured. The values are analyzed using the modified Stokes-Einstein equation and compared with the theoretical upper, D max, and lower, D min, bounds of the diffusion coefficients. This approach allows the interpretation of D values, whilst avoiding dealing with some of the uncertainties associated with molecular size in the Stokes-Einstein equation. The neutral decamethylferrocene was found to obey the Stokes-Einstein equation whereas the charged metallocene species had values which were less than the theoretical minimum, which was attributed to a larger than expected particle size caused by ion pairing. The importance of considering the modifications of the Stokes-Einstein equation is also highlighted.

Heterostructures involving two-dimensional (2D) transition metal dichalcogenides and other materials such as graphene have a strong potential to be the fundamental building block of many electronic and optoelectronic applications. The integration and scalable fabrication of such heterostructures are of the essence in unleashing the potential of these materials in new technologies. For the first time, we demonstrate the growth of few-layer MoS

This study examined performance differences in the traditional paper-and-pencil and new digital versions of the Coding subtest from the Wechsler Intelligence Scale for Children-Fifth Edition (WISC-V) using a cross-sectional sample. A total of 212 school-aged children between 6 and 14 years old were included in the sample, with 116 completing the paper version and 96 completing the digital version administered on a tablet in 2017-2018. One-way ANOVA revealed a significant difference with large effect size between mean scaled scores, with the digital version resulting in higher scaled scores than the paper version

Heterostructures involving two-dimensional (2D) transition metal dichalcogenides and other materials such as graphene have a strong potential to be the fundamental building block of many electronic and opto-electronic applications. The integration and scalable fabrication of such heterostructures is of essence in unleashing the potential of these materials in new technologies. For the first time, we demonstrate the growth of few-layer MoS2 films on graphene via non-aqueous electrodeposition. Through methods such as scanning and transmission electron microscopy, atomic force microscopy, Raman spectroscopy, energy and wavelength dispersive X-ray spectroscopies and X-ray photoelectron spectroscopy, we show that this deposition method can produce large-area MoS2 films with high quality and uniformity over graphene. We reveal the potential of these heterostructures by measuring the photo-induced current through the film. These results pave the way towards developing the electrodeposition method for the large-scale growth of heterostructures consisting of varying 2D materials for many applications., 11 pages and 6 figures

A promising development in school-based prevention and intervention science is the use of applied social–psychological concepts to improve students’ experiences and outcomes in school. Mounting evidence from rigorous studies supports the efficacy of theoretically informed interventions grounded in social psychology, including growth mindset and values affirmation. One of particular utility for educators and school psychologists is wise feedback, which is a relational technique for providing skillful, constructive feedback. The overarching purpose of this study was to further explore the potential efficacy of wise feedback as a targeted intervention for students exhibiting social problem behaviors resulting in negative outcomes. Wise feedback was implemented using a multiple-baseline design with six students exhibiting signs of dropout (i.e., lack of trust and sense of belonging in a school) in ninth grade. Visual and statistical analysis indicated improvement in the students’ sense of belonging a...

Dairy sheep produce an effluent stream from the milking parlour that is either applied directly to land via a sump and spray irrigator, or is stored in an effluent pond before application. In order to characterise this effluent stream, a monitoring programme was undertaken with effluent samples collected from two case study sheep milking farms over two lactation seasons (2014/2015 and 2015/2016), and a third over one lactation period (2015/2016). Typical effluent volumes generated ranged between 4 and 10 L ewe−1 day−1 for the 130–200-day lactation. The mean physical and chemical attributes of effluent samples generated by the milking parlours were: 0.54% dry matter (DM), 220 g nitrogen (N) m−3, 32 g phosphorus (P) m−3, 150 g potassium (K) m−3 and 22 g sulphur (S) m−3. The mean nutrient concentrations of dairy sheep effluent are lower than values reported for dairy goat (P & S only) and dairy cow effluents (N, P, K and S).