Immobilisation of engineered molecules on electrodes and optical surfaces,

ABSTRACT Monolayers of genetically modified proteins with an hexahistidine tag, (His)6, were obtained by using a Ni -NTA chelator synthesized on gold sputtered surfaces (via sulphide bonds), or on gold and graphite (via sililating agents) working electrodes of screen-printed devices. Two kinds of proteins were produced and purified for this study: a) a recombinant antibody, derived from the 'single chain Fv' ( scFv) format; b) a photosystem II (PSII) core complex isolated from the mutant strain CP43-H of the thermophilic cyanobacterium Synechococcus elongatus. An scFv, previously isolated from a synthetic 'phage display' library, was further engineered with an alkaline phosphatase activity genetically added between the carbossi-terminal of the scFvs and the (His)6 to allow direct measurement of immobilisation. Renewable specific binding of (His)6-proteins to gold and graphite surfaces and fast and sensitive electrochemical or optical detection of analytes were obtained. Additionally, "on chip" protein preconcentration was conveniently achieved for biosensing purposes, starting from crude unpurified extracts and avoiding protein purification steps

Timing Analysis of the 2022 Outburst of the Accreting Millisecond X-Ray Pulsar SAX J1808.4-3658: Hints of an Orbital Shrinking

We present a pulse timing analysis of NICER observations of the accreting millisecond X-ray pulsar SAX J1808.4-3658 during the outburst that started on 2022 August 19. Similar to previous outbursts, after decaying from a peak luminosity of ≃1 × 1036 erg s-1 in about a week, the pulsar entered a ~1 month long reflaring stage. Comparison of the average pulsar spin frequency during the outburst with those previously measured confirmed the long-term spin derivative of ν˙SD=−(1.15±0.06)×10−15 Hz s-1, compatible with the spin-down torque of a ≈1026 G cm3 rotating magnetic dipole. For the first time in the last twenty years, the orbital phase evolution shows evidence for a decrease of the orbital period. The long-term behavior of the orbit is dominated by an ~11 s modulation of the orbital phase epoch consistent with a ~21 yr period. We discuss the observed evolution in terms of a coupling between the orbit and variations in the mass quadrupole of the companion star

Rosina - Rosetta Orbiter Spectrometer for Ion and Neutral Analysis

The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) will answer important questions posed by the mission's main objectives. After Giotto, this will be the first time the volatile part of a comet will be analyzed in situ. This is a very important investigation, as comets, in contrast to meteorites, have maintained most of the volatiles of the solar nebula. To accomplish the very demanding objectives through all the different phases of the comet's activity, ROSINA has unprecedented capabilities including very wide mass range (1 to >300 amu), very high mass resolution (m/Δ m > 3000, i.e. the ability to resolve CO from N2 and 13C from 12CH), very wide dynamic range and high sensitivity, as well as the ability to determine cometary gas velocities, and temperature. ROSINA consists of two mass spectrometers for neutrals and primary ions with complementary capabilities and a pressure sensor. To ensure that absolute gas densities can be determined, each mass spectrometer carries a reservoir of a calibrated gas mixture allowing in-flight calibration. Furthermore, identical flight-spares of all three sensors will serve for detailed analysis of all relevant parameters, in particular the sensitivities for complex organic molecules and their fragmentation patterns in our electron bombardment ion source

The Impact of the Quantum Data Plane Overhead on the Throughput

Currently, although a standard distinction between quantum data plane and quantum control plane is still missing, preliminary works specify that classical control messages operating at the granularity of individual qubits and entangled pairs are, in terms of functionalities, closer to classical packet headers than control plane messages. Thus, they have been considered as part of the quantum data plane, by contributing to its overall overhead. As a consequence, the very concept of throughput needs to be re-defined and studied within the Quantum Internet. The aim of this treatise is to shed the light on this crucial aspect. Specifically, we conduct a theoretical analysis to understand the factors determining the overhead in the quantum data plane and their reflection on the throughput. The analysis is crucial and preliminary for designing any effective quantum communication protocol. Specifically, we derive closed-form expressions of the throughput in different scenarios, and the nonlinear relationship between throughput, entanglement throughput and classical bit rate is disclosed. Finally, we validate the theoretical analysis through numerical results conducted on the IBM Q-Experience platform

Quantum Internet: from Medium Access Control to Entanglement Access Control

Multipartite entanglement plays a crucial role for the design of the Quantum Internet, due to its potentiality of significantly increasing the network performance. In this paper, we design an entanglement access control protocol for multipartite state, which exhibits several attractive features. Specifically, the designed protocol is able to jointly extract in a distributed way an EPR pair from the original multipartite entangled state shared by the set of network nodes, and to univocally determines the identities of the transmitter node and the receiver node in charge of using the extracted EPR pair. Furthermore, the protocol avoids to delegate the signaling arising with entanglement access control to the classical network, with the exception of the unavoidable classical communications needed for EPR extraction and qubit teleportation. Finally, the protocol supports the anonymity of the entanglement accessing nodes