Aryldiazonium tetrafluoroborate salts as green and efficient coupling partners for the Suzuki-Miyaura reaction : from optimisation to mole scale

The use of aryldiazonium tetrafluoroborate salts as coupling partners in the Suzuki-Miyaura reaction was investigated from a process chemistry perspective including safety evaluation, solvent and catalyst screening and multi-variate factor optimization. Optimised conditions were applied to a range of substrates to evaluate the scope and limitations of the reaction and one example was carried out on mole-scale to demonstrate the practicality and scalability of the proces

C–H arylation of heterocyclic N oxides through in-situ diazotisation of anilines without added promoters : a green and selective coupling process

A green and selective method for the generation of bi-aryl compounds through C—H arylation of heterocyclic N-oxides is presented in which the addition of ascorbic acid as a promoter is not required for either the generation of an aryldiazonium species or the subsequent arylation. Reaction conditions were optimized through Multivariate Data Analysis, including Orthogonal Projections to Latent Structures (OPLS) and Design of Experiments (DoE) methodologies resulting in further sustainability improvements, and were then applied to a range of substrates to establish the scope and limitations of the process. The reaction was studied using in-situ infra-red spectroscopy and a mechanism is presented that accounts for the available data from this and previous studies. The reaction was also per-formed on a multigram scale, with calorimetry studies to support further scale-up of this promoter-free transformation

Thermoelectric properties and low thermal conductivity of nanocomposite ZrTe5 under magnetic field

Zirconium pentatelluride (ZrTe5) single crystal has recently received significant attention because of its quantum electronic transport properties and is regarded as a promising candidate for low-temperature thermoelectric cooling and spintronic applications. However, single crystal of ZrTe5 has generally small sizes and can only be produced in small quantities using a complicated process, whereas ZrTe5 polycrystals are easily produced and their properties are easily adjusted. In this study, we focus on the magneto-transport properties at low temperatures of nanocomposites of ZrTe5 produced using both hand-milling and ball-milling processes to investigate the impact of the microstructure. The ball-milled sample shows a low thermal conductivity of 1 W m−1 K−1, which is almost a constant below 300 K. However, due to its small grain sizes, the electron mobility is significantly decreased, thus their thermoelectric performances are not as good as that of the hand-milled sample. Also, below 25 K, the resistivity and the Seebeck coefficient of the ball-milled sample are decreased, which is associated with the energy barrier at their grain boundaries. Due to the larger grain sizes and fewer defects in the hand-milled sample, the external magnetic field shows a significant influence on its thermoelectric properties at low temperatures. These results indicate that polycrystalline ZrTe5 with large grain sizes may exhibit similar quantum properties as those of single crystals

Wide range local resistance imaging on fragile materials by conducting probe atomic force microscopy in intermittent contact mode

International audienceAn imaging technique associating a slowly intermittent contact mode of atomic force microscopy (AFM) with a home-made multi-purpose resistance sensing device is presented. It aims at extending the widespread resistance measurements classically operated in contact mode AFM to broaden their application fields to soft materials (molecular electronics, biology) and fragile or weakly anchored nano-objects, for which nanoscale electrical characterization is highly demanded and often proves to be a challenging task in contact mode. Compared with the state of the art concerning less aggressive solutions for AFM electrical imaging, our technique brings a significantly wider range of resistance measurement (over 10 decades) without any manual switching, which is a major advantage for the characterization of materials with large on-sample resistance variations. After describing the basics of the set-up, we report on preliminary investigations focused on academic samples of self-assembled monolayers with various thicknesses as a demonstrator of the imaging capabilities of our instrument, from qualitative and semi-quantitative viewpoints. Then two application examples are presented, regarding an organic photovoltaic thin film and an array of individual vertical carbon nanotubes. Both attest the relevance of the technique for the control and optimization of technological processe

A Glucose BioFuel Cell Implanted in Rats

Powering future generations of implanted medical devices will require cumbersome transcutaneous energy transfer or harvesting energy from the human body. No functional solution that harvests power from the body is currently available, despite attempts to use the Seebeck thermoelectric effect, vibrations or body movements. Glucose fuel cells appear more promising, since they produce electrical energy from glucose and dioxygen, two substrates present in physiological fluids. The most powerful ones, Glucose BioFuel Cells (GBFCs), are based on enzymes electrically wired by redox mediators. However, GBFCs cannot be implanted in animals, mainly because the enzymes they rely on either require low pH or are inhibited by chloride or urate anions, present in the Extra Cellular Fluid (ECF). Here we present the first functional implantable GBFC, working in the retroperitoneal space of freely moving rats. The breakthrough relies on the design of a new family of GBFCs, characterized by an innovative and simple mechanical confinement of various enzymes and redox mediators: enzymes are no longer covalently bound to the surface of the electron collectors, which enables use of a wide variety of enzymes and redox mediators, augments the quantity of active enzymes, and simplifies GBFC construction. Our most efficient GBFC was based on composite graphite discs containing glucose oxidase and ubiquinone at the anode, polyphenol oxidase (PPO) and quinone at the cathode. PPO reduces dioxygen into water, at pH 7 and in the presence of chloride ions and urates at physiological concentrations. This GBFC, with electrodes of 0.133 mL, produced a peak specific power of 24.4 µW mL−1, which is better than pacemakers' requirements and paves the way for the development of a new generation of implantable artificial organs, covering a wide range of medical applications

A novel algorithmic approach to generate consensus treatment guidelines in adult Acute Myeloid Leukaemia

Induction therapy for acute myeloid leukaemia (AML) has changed with the approval of a number of new agents. Clinical guidelines can struggle to keep pace with an evolving treatment and evidence landscape and therefore identifying the most appropriate front-line treatment is challenging for clinicians. Here, we combined drug eligibility criteria and genetic risk stratification into a digital format, allowing the full range of possible treatment eligibility scenarios to be defined. Using exemplar cases representing each of the 22 identified scenarios, we sought to generate consensus on treatment choice from a panel of nine aUK AML experts. We then analysed >2500 real-world cases using the same algorithm, confirming the existence of 21/22 of these scenarios and demonstrating that our novel approach could generate a consensus AML induction treatment in 98% of cases. Our approach, driven by the use of decision trees, is an efficient way to develop consensus guidance rapidly and could be applied to other disease areas. It has the potential to be updated frequently to capture changes in eligibility criteria, novel therapies and emerging trial data. An interactive digital version of the consensus guideline is available

Generation of a single-cycle acoustic pulse: a scalable solution for transport in single-electron circuits

The synthesis of single-cycle, compressed optical and microwave pulses sparked novel areas of fundamental research. In the field of acoustics, however, such a generation has not been introduced yet. For numerous applications, the large spatial extent of surface acoustic waves (SAW) causes unwanted perturbations and limits the accuracy of physical manipulations. Particularly, this restriction applies to SAW-driven quantum experiments with single flying electrons, where extra modulation renders the exact position of the transported electron ambiguous and leads to undesired spin mixing. Here, we address this challenge by demonstrating single-shot chirp synthesis of a strongly compressed acoustic pulse. Employing this solitary SAW pulse to transport a single electron between distant quantum dots with an efficiency exceeding 99%, we show that chirp synthesis is competitive with regular transduction approaches. Performing a time-resolved investigation of the SAW-driven sending process, we outline the potential of the chirped SAW pulse to synchronize single-electron transport from many quantum-dot sources. By superimposing multiple pulses, we further point out the capability of chirp synthesis to generate arbitrary acoustic waveforms tailorable to a variety of (opto)nanomechanical applications. Our results shift the paradigm of compressed pulses to the field of acoustic phonons and pave the way for a SAW-driven platform of single-electron transport that is precise, synchronized, and scalable.Comment: To be published in Physical Review

Coulomb-mediated antibunching of an electron pair surfing on sound

Electron flying qubits are envisioned as potential information link within a quantum computer, but also promise -- alike photonic approaches -- a self-standing quantum processing unit. In contrast to its photonic counterpart, electron-quantum-optics implementations are subject to Coulomb interaction, which provide a direct route to entangle the orbital or spin degree of freedom. However, the controlled interaction of flying electrons at the single particle level has not yet been established experimentally. Here we report antibunching of a pair of single electrons that is synchronously shuttled through a circuit of coupled quantum rails by means of a surface acoustic wave. The in-flight partitioning process exhibits a reciprocal gating effect which allows us to ascribe the observed repulsion predominantly to Coulomb interaction. Our single-shot experiment marks an important milestone on the route to realise a controlled-phase gate for in-flight quantum manipulations

RNA interference in Lepidoptera: an overview of successful and unsuccessful studies and implications for experimental design

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