Multifrequency Nanomechanical Mass Spectrometer Prototype for Measuring Viral Particles Using Optomechanical Disk Resonators

We report on optomechanical GaAs disk resonators with ultrahigh quality factor-frequency product Q×f. Disks standing on a simple pedestal exhibit GHz mechanical breathing modes attaining a Q×f of 1013 measured under vacuum at cryogenic temperature. Clamping losses are found to be the dominant source of dissipation. An improved disk resonator geometry integrating a shield within the pedestal is then proposed, and its working principles and performances are investigated by numerical simulations. For dimensions compatible with fabrication constraints, the clamping-loss-limited Q reaches 107–109 corresponding to Q×f equals 1016–1018. This shielded pedestal approach applies to any heterostructure presenting an acoustic mismatch.

Activation experiments are a perfect tool to perform systematic studies due to their high sensitivity and selectivity. Exemplary applications to understand the nucleosynthesis of the p nuclei – such as the optimization of optical particle-nucleus potentials and investigations of (γ,n) reactions in a broad mass range – are presented. Some recent and partly preliminary results are briefly discussed.

Microfluidic flow focusing devices are widely used to generate steep chemical concentration gradients at the interface between miscible or partially miscible streams. In this study, first we present an optimised protocol for the manufacturing of composite flow focusing devices, consisting of a micropatterned layer of Norland Optical Adhesive (NOA) glue bound to flat or microgrooved silicon substrates. Then, three different applications of these devices are demonstrated, namely (i) particle spreading and focusing in continuous flows past flat substrates, (ii) particle accumulation within the dead-end cavities of microgrooved substrates and (iii) synthesis of nano-sized liposomes. Colloidal particle spreading, focusing and accumulation were achieved through diffusiophoresis transport induced by salt concentration gradients at the interface between electrolyte streams. Epi-fluorescence microscopy was adopted to characterise the spatio-temporal distribution of silica and polystyrene nanoparticles in the devices with flat or microgrooved surfaces. The effects of particle zeta potential and groove thickness on particle dynamics were investigated. 1,2-di-(9Z-octadecenoyl)-sn-glycero-3-phosphocholine (DOPC) liposomes were generated by hydrodynamic focusing and characterised via dynamic light scattering. Liposome populations with controlled narrow size distributions could be achieved by adjusting the flow rate conditions in the devices. This work demonstrates that composite NOA/silicon flow junction devices offer a competitive alternative to conventional PDMS chips and can support a wide range of microfluidic applications, including nanoparticle synthesis, characterisation and filtration, drug encapsulation and biochemical analysis.

Unbiased analysis of asphaltene molecules by mass spectrometry requires that the three fundamental steps in mass spectrometry-volatilization, ionization, and mass analysis-are performed reliably and with nearly equivalent efficiency for nearly all of the diverse components in asphaltenes. Here, we examine these three processes and the overall analysis mechanism in two forms of laser-based mass spectrometry: laser desorption laser ionization mass spectrometry (L2MS) and surface-assisted laser desorption/ionization mass spectrometry (SALDI). In L2MS, volatilization occurs by laser desorption, which is a thermal process not selective for any particular molecular configuration; ionization occurs by single-photon ionization, which is a soft and universal method applicable to virtually all organic molecules and aggregates; and mass analysis occurs by time-of-flight mass spectrometry, which has a nearly constant sensitivity across a broad mass range. These factors suggest that L2MS should analyze asphaltenes wit...

There is considerable interest worldwide in the research which could be done at a next generation, advanced radioactive beam facility. To generate high quality, intense beams of accelerated radionuclides via the {open_quotes}isotope separator on-line{close_quotes} (ISOL) method requires two major accelerator components: a high power (100 kW) driver device to produce radionuclides in a production target/ion source complex, and a secondary beam accelerator to produce beams of radioactive ions up to energies on the order of 10 MeV per nucleon over a broad mass range. In reviewing the technological challenges of such a facility, several types of modem linear accelerators appear well suited. This paper reviews the properties of the linacs currently under construction and those proposed for future facilities for use either as the driver device or the radioactive beam post-accelerator. Other choices of accelerators, such as cyclotrons, for either the driver or secondary beam devices of a radioactive beam complex will also be compared. Issues to be addressed for the production accelerator include the choice of ion beam types to be used for cost-effective production of radionuclides. For the post-accelerator the choice of ion source technology is critical and dictates the charge-to-mass requirements at the injection stage.

Carbon, hydrogen, nitrogen, oxygen, and sulfur are the main elements involved in the solid-phase chemistry of various astrophysical environments. Among these elements, sulfur chemistry is probably the least well understood. We investigated whether sulfur ion bombardment within simple astrophysical ice analogs (originating from H2O:CH3OH:NH3, 2:1:1) could trigger the formation of complex organosulfur molecules. Over 1100 organosulfur (CHNOS) molecular formulas (12% of all assigned signals) were detected in resulting refractory residues within a broad mass range (from 100 to 900 amu, atomic mass unit). This finding indicates a diverse, rich and active sulfur chemistry that could be relevant for Kuiper Belt objects (KBO) ices, triggered by high-energy ion implantation. The putative presence of organosulfur compounds within KBO ices or on other icy bodies might influence our view on the search of habitability and biosignatures.

Analysis and Quantitation of Insect Juvenile Hormones Using Chemical Ionization Ion-Trap Mass Spectrometry

The characteristics of electric dipole strength built on highly-excited continuum states

Differences of excitation energy among analogue states in a broad mass range are calculated in the framework of the shell model by introducing isospin breaking interactions. Mirror and triplet energy differences along the N=Z line from mass A ~ 20 to A ~ 60 have been systematically studied using the same method. It is shown that in all cases an additional term not directly associated to the electromagnetic interaction is needed to reproduce the experimental data.

Prefocusing inside a linear ion beam guide—A SIMION study

Resolution and mass accuracy in matrix-assisted laser desorption ionization- time-of-flight

The GELFREE 8100 Fractionation System is a novel protein fractionation system designed to maximize protein recovery during molecular weight based fractionation. The system is comprised of single-use, 8-sample capacity cartridges and a benchtop GELFREE Fractionation Instrument. During separation, a constant voltage is applied between the anode and cathode reservoirs, and each protein mixture is electrophoretically driven from a loading chamber into a specially designed gel column gel. Proteins are concentrated into a tight band in a stacking gel, and separated based on their respective electrophoretic mobilities in a resolving gel. As proteins elute from the column, they are trapped and concentrated in liquid phase in the collection chamber, free of the gel. The instrument is then paused at specific time intervals, and fractions are collected using a pipette. This process is repeated until all desired fractions have been collected. If fewer than 8 samples are run on a cartridge, any unused chambers can be used in subsequent separations. This novel technology facilitates the quick and simple separation of up to 8 complex protein mixtures simultaneously, and offers several advantages when compared to previously available fractionation methods. This system is capable of fractionating up to 1mg of total protein per channel, for a total of 8 mg per cartridge. Intact proteins over a broad mass range are separated on the basis of molecular weight, retaining important physiochemical properties of the analyte. The liquid phase entrapment provides for high recovery while eliminating the need for band or spot cutting, making the fractionation process highly reproducible.

We use simulated merger trees of galaxy-cluster halos to study the effect of the halo concentration distribution on strong lensing and X-ray emission. Its log-normal shape typically found in simulations favors outliers with high concentration. Since, at fixed mass, more concentrated halos tend to be more efficient lenses, the scatter in the concentration increases the strong-lensing optical depth by <50%. Within cluster samples, mass and concentration have counteracting effects on strong lensing and X-ray emission because the concentration decreases for increasing mass. Selecting clusters by concentration thus has no effect on the lensing cross section. The most efficiently lensing and hottest clusters are typically the least concentrated in samples with a broad mass range. Among cluster samples with a narrow mass range, however, the most strongly lensing and X-ray brightest clusters are typically 10% to 25% more concentrated.

Extensions of the standard model of particle physics, in particular those based on string theory, often predict a new U(1) gauge symmetry in a hidden sector. The corresponding gauge boson, called hidden photon, naturally interacts with the ordinary photon via gauge kinetic mixing, leading to photon - hidden photon oscillations. In this framework, one expects photon disappearance as a function of the mass of the hidden photon and the mixing angle, loosely constrained from theory. Several experiments have been carried out or are planned to constrain the mass-mixing plane. In this contribution we derive new constraints on the hidden photon parameters, using very high energy gamma-rays detected from the Crab Nebula, whose broad-band spectral characteristics are well understood. The very high energy gamma-ray observations offer the possibility to provide bounds in a broad mass range at a previously unexplored energy and distance scale. Using existing data that were taken with several Cherenkov telescopes, we discuss our results in the context of current constraints and consider the possibilities of using astrophysical data to search for hidden photon signatures.

The past few years have seen a renewed interest in the search for light particle dark matter. ABRACADABRA is a new experimental program to search for axion dark matter over a broad range of masses, $10^{-12}\lesssim m_a\lesssim10^{-6}$ eV. ABRACADABRA-10 cm is a small-scale prototype for a future detector that could be sensitive to QCD axion couplings. In this paper, we present the details of the design, construction, and data analysis for the first axion dark matter search with the ABRACADABRA-10 cm detector. We include a detailed discussion of the statistical techniques used to extract the limit from the first result with an emphasis on creating a robust statistical footing for interpreting those limits.